| blob | 11aca57239f0cc08b8674a6cfefda414ec31c20c |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2014, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License distributed with GNAT; see file COPYING3. If not see *
19 * <http://www.gnu.org/licenses/>. *
20 * *
21 * GNAT was originally developed by the GNAT team at New York University. *
22 * Extensive contributions were provided by Ada Core Technologies Inc. *
23 * *
24 ****************************************************************************/
77 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
78 for fear of running out of stack space. If we need more, we use xmalloc
79 instead. */
80 #define ALLOCA_THRESHOLD 1000
82 /* In configurations where blocks have no end_locus attached, just
83 sink assignments into a dummy global. */
84 #ifndef BLOCK_SOURCE_END_LOCATION
86 #define BLOCK_SOURCE_END_LOCATION(BLOCK) block_end_locus_sink
87 #endif
89 /* Pointers to front-end tables accessed through macros. */
100 /* Highest number in the front-end node table. */
103 /* Current node being treated, in case abort called. */
104 Node_Id error_gnat_node;
106 /* True when gigi is being called on an analyzed but unexpanded
107 tree, and the only purpose of the call is to properly annotate
108 types with representation information. */
111 /* Current filename without path. */
115 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
118 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
119 of unconstrained array IN parameters to avoid emitting a great deal of
120 redundant instructions to recompute them each time. */
124 tree first;
125 tree last;
126 tree length;
127 };
134 bitmap named_ret_val;
137 };
139 #define f_parm_attr_cache \
140 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
142 #define f_named_ret_val \
143 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
145 #define f_other_ret_val \
146 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
148 #define f_gnat_ret \
149 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
151 /* A structure used to gather together information about a statement group.
152 We use this to gather related statements, for example the "then" part
153 of a IF. In the case where it represents a lexical scope, we may also
154 have a BLOCK node corresponding to it and/or cleanups. */
161 };
165 /* List of unused struct stmt_group nodes. */
168 /* A structure used to record information on elaboration procedures
169 we've made and need to process.
171 ??? gnat_node should be Node_Id, but gengtype gets confused. */
177 };
181 /* Stack of exception pointer variables. Each entry is the VAR_DECL
182 that stores the address of the raised exception. Nonzero means we
183 are in an exception handler. Not used in the zero-cost case. */
186 /* In ZCX case, current exception pointer. Used to re-raise it. */
189 /* Stack for storing the current elaboration procedure decl. */
192 /* Stack of labels to be used as a goto target instead of a return in
193 some functions. See processing for N_Subprogram_Body. */
196 /* Stack of variable for the return value of a function with copy-in/copy-out
197 parameters. See processing for N_Subprogram_Body. */
200 /* Structure used to record information for a range check. */
202 tree low_bound;
203 tree high_bound;
204 tree type;
205 tree invariant_cond;
206 };
211 /* Structure used to record information for a loop. */
213 tree stmt;
214 tree loop_var;
216 };
221 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
224 /* The stacks for N_{Push,Pop}_*_Label. */
229 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
266 /* Hooks for debug info back-ends, only supported and used in a restricted set
267 of configurations. */
270 \f
271 /* This is the main program of the back-end. It sets up all the table
272 structures and then generates code. */
274 void
287 Nat number_file,
289 Entity_Id standard_boolean,
290 Entity_Id standard_integer,
291 Entity_Id standard_character,
292 Entity_Id standard_long_long_float,
293 Entity_Id standard_exception_type,
294 Int gigi_operating_mode)
295 {
296 Node_Id gnat_iter;
297 Entity_Id gnat_literal;
317 {
318 /* Use the identifier table to make a permanent copy of the filename as
319 the name table gets reallocated after Gigi returns but before all the
320 debugging information is output. The __gnat_to_canonical_file_spec
321 call translates filenames from pragmas Source_Reference that contain
322 host style syntax not understood by gdb. */
324 = IDENTIFIER_POINTER
325 (get_identifier
326 (__gnat_to_canonical_file_spec
329 /* We rely on the order isomorphism between files and line maps. */
332 /* We create the line map for a source file at once, with a fixed number
333 of columns chosen to avoid jumping over the next power of 2. */
338 }
342 /* Declare the name of the compilation unit as the first global
343 name in order to make the middle-end fully deterministic. */
347 /* Initialize ourselves. */
352 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
353 errors. */
355 {
358 }
360 /* Enable GNAT stack checking method if needed */
364 /* Retrieve alignment settings. */
368 /* Record the builtin types. Define `integer' and `character' first so that
369 dbx will output them first. */
375 /* Save the type we made for integer as the type for Standard.Integer. */
380 /* Likewise for character as the type for Standard.Character. */
385 /* Likewise for boolean as the type for Standard.Boolean. */
409 /* Now declare run-time functions. */
412 /* malloc is a function declaration tree for a function to allocate
413 memory. */
414 malloc_decl
420 /* free is a function declaration tree for a function to free memory. */
421 free_decl
424 ptr_void_type_node,
425 NULL_TREE),
427 Empty);
429 /* This is used for 64-bit multiplication with overflow checking. */
431 mulv64_decl
436 Empty);
438 /* Name of the _Parent field in tagged record types. */
441 /* Name of the Exception_Data type defined in System.Standard_Library. */
442 exception_data_name_id
445 /* Make the types and functions used for exception processing. */
446 jmpbuf_type
452 /* Functions to get and set the jumpbuf pointer for the current thread. */
453 get_jmpbuf_decl
454 = create_subprog_decl
460 set_jmpbuf_decl
461 = create_subprog_decl
464 NULL_TREE),
468 /* setjmp returns an integer and has one operand, which is a pointer to
469 a jmpbuf. */
470 setjmp_decl
471 = create_subprog_decl
474 NULL_TREE),
479 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
480 address. */
481 update_setjmp_buf_decl
482 = create_subprog_decl
489 /* Hooks to call when entering/leaving an exception handler. */
490 ftype
493 begin_handler_decl
499 end_handler_decl
505 unhandled_except_decl
507 NULL_TREE,
512 reraise_zcx_decl
516 /* Indicate that these never return. */
523 /* If in no exception handlers mode, all raise statements are redirected to
524 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
525 this procedure will never be called in this mode. */
527 {
528 tree decl
529 = create_subprog_decl
532 build_pointer_type
542 }
543 else
544 {
545 /* Otherwise, make one decl for each exception reason. */
551 i == CE_Index_Check_Failed
555 }
557 /* Set the types that GCC and Gigi use from the front end. */
560 /* Make other functions used for exception processing. */
561 get_excptr_decl
562 = create_subprog_decl
565 NULL_TREE),
569 set_exception_parameter_decl
570 = create_subprog_decl
573 ptr_void_type_node,
574 ptr_void_type_node,
575 NULL_TREE),
578 raise_nodefer_decl
579 = create_subprog_decl
583 NULL_TREE),
586 /* Indicate that it never returns. */
591 TYPE_QUAL_VOLATILE);
593 /* Build the special descriptor type and its null node if needed. */
595 {
607 {
608 tree field
615 elt--;
616 }
621 }
623 longest_float_type_node
626 /* Dummy objects to materialize "others" and "all others" in the exception
627 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
628 the types to use. */
629 others_decl
632 unsigned_char_type_node,
635 all_others_decl
638 unsigned_char_type_node,
641 unhandled_others_decl
644 unsigned_char_type_node,
649 /* Install the builtins we might need, either internally or as
650 user available facilities for Intrinsic imports. */
658 /* Process any Pragma Ident for the main unit. */
663 /* If we are using the GCC exception mechanism, let GCC know. */
667 /* Initialize the GCC support for FP operations. */
670 /* Now translate the compilation unit proper. */
673 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
674 the very end to avoid having to second-guess the front-end when we run
675 into dummy nodes during the regular processing. */
680 /* Finally see if we have any elaboration procedures to deal with. */
682 {
685 /* We should have a BIND_EXPR but it may not have any statements in it.
686 If it doesn't have any, we have nothing to do except for setting the
687 flag on the GNAT node. Otherwise, process the function as others. */
693 else
694 {
698 }
699 }
701 /* Destroy ourselves. */
705 /* We cannot track the location of errors past this point. */
707 }
708 \f
709 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
710 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
712 static tree
714 {
723 {
725 ftype
727 build_pointer_type
730 }
731 else
732 {
737 ftype
739 build_pointer_type
743 }
745 result
750 /* Indicate that it never returns. */
757 }
758 \f
759 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
760 an N_Attribute_Reference. */
762 static int
764 {
766 {
806 }
807 }
809 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
810 is the type that will be used for GNAT_NODE in the translated GNU tree.
811 CONSTANT indicates whether the underlying object represented by GNAT_NODE
812 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
813 whether its value is the address of a constant and ALIASED whether it is
814 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
816 The function climbs up the GNAT tree starting from the node and returns 1
817 upon encountering a node that effectively requires an lvalue downstream.
818 It returns int instead of bool to facilitate usage in non-purely binary
819 logic contexts. */
821 static int
824 {
828 {
838 /* If the parameter is by reference, an lvalue is required. */
844 /* Only the array expression can require an lvalue. */
848 /* ??? Consider that referencing an indexed component with a
849 non-constant index forces the whole aggregate to memory.
850 Note that N_Integer_Literal is conservative, any static
851 expression in the RM sense could probably be accepted. */
858 /* ... fall through ... */
861 /* Only the array expression can require an lvalue. */
875 /* We need to preserve addresses through a renaming. */
879 /* We cannot use a constructor if this is an atomic object because
880 the actual assignment might end up being done component-wise. */
884 /* We don't use a constructor if this is a class-wide object
885 because the effective type of the object is the equivalent
886 type of the class-wide subtype and it smashes most of the
887 data into an array of bytes to which we cannot convert. */
892 /* We cannot use a constructor if the LHS is an atomic object because
893 the actual assignment might end up being done component-wise. */
903 /* ... fall through ... */
907 /* We must look through all conversions because we may need to bypass
908 an intermediate conversion that is meant to be purely formal. */
914 /* We should only reach here through the N_Qualified_Expression case.
915 Force an lvalue for composite types since a block-copy to the newly
916 allocated area of memory is made. */
920 /* We look through dereferences for address of constant because we need
921 to handle the special cases listed above. */
927 /* ... fall through ... */
931 }
934 }
936 /* Return true if T is a constant DECL node that can be safely replaced
937 by its initializer. */
939 static bool
941 {
945 /* Return false for aggregate types that contain a placeholder since
946 their initializers cannot be manipulated easily. */
953 }
955 /* Return an expression equivalent to EXP but where constant DECL nodes
956 have been replaced by their initializer. */
958 static tree
960 {
962 tree op0;
965 {
1002 }
1005 }
1007 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1008 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1009 to where we should place the result type. */
1011 static tree
1013 {
1017 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1018 specific circumstances only, so evaluated lazily. < 0 means
1019 unknown, > 0 means known true, 0 means known false. */
1022 /* If GNAT_NODE is a constant, whether we should use the initialization
1023 value instead of the constant entity, typically for scalars with an
1024 address clause when the parent doesn't require an lvalue. */
1027 /* If the Etype of this node does not equal the Etype of the Entity,
1028 something is wrong with the entity map, probably in generic
1029 instantiation. However, this does not apply to types. Since we sometime
1030 have strange Ekind's, just do this test for objects. Also, if the Etype of
1031 the Entity is private, the Etype of the N_Identifier is allowed to be the
1032 full type and also we consider a packed array type to be the same as the
1033 original type. Similarly, a class-wide type is equivalent to a subtype of
1034 itself. Finally, if the types are Itypes, one may be a copy of the other,
1035 which is also legal. */
1050 == Packed_Array_Impl_Type
1059 /* If this is a reference to a deferred constant whose partial view is an
1060 unconstrained private type, the proper type is on the full view of the
1061 constant, not on the full view of the type, which may be unconstrained.
1063 This may be a reference to a type, for example in the prefix of the
1064 attribute Position, generated for dispatching code (see Make_DT in
1065 exp_disp,adb). In that case we need the type itself, not is parent,
1066 in particular if it is a derived type */
1073 {
1076 }
1077 else
1078 {
1079 /* We want to use the Actual_Subtype if it has already been elaborated,
1080 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1081 simplify things. */
1089 else
1091 }
1093 /* Expand the type of this identifier first, in case it is an enumeral
1094 literal, which only get made when the type is expanded. There is no
1095 order-of-elaboration issue here. */
1098 /* If this is a non-imported elementary constant with an address clause,
1099 retrieve the value instead of a pointer to be dereferenced unless
1100 an lvalue is required. This is generally more efficient and actually
1101 required if this is a static expression because it might be used
1102 in a context where a dereference is inappropriate, such as a case
1103 statement alternative or a record discriminant. There is no possible
1104 volatile-ness short-circuit here since Volatile constants must be
1105 imported per C.6. */
1110 {
1114 }
1117 {
1118 /* If this is a deferred constant, the initializer is attached to
1119 the full view. */
1124 }
1125 else
1128 /* Some objects (such as parameters passed by reference, globals of
1129 variable size, and renamed objects) actually represent the address
1130 of the object. In that case, we must do the dereference. Likewise,
1131 deal with parameters to foreign convention subprograms. */
1136 {
1139 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1142 gnu_result
1145 /* If it's a CONST_DECL, return the underlying constant like below. */
1152 /* If it's a renaming pointer and, either the renamed object is constant
1153 or we are at the right binding level, we can reference the renamed
1154 object directly, since it is constant or has been protected against
1155 multiple evaluations. */
1164 /* Otherwise, do the final dereference. */
1165 else
1166 {
1176 }
1177 }
1179 /* If we have a constant declaration and its initializer, try to return the
1180 latter to avoid the need to call fold in lots of places and the need for
1181 elaboration code if this identifier is used as an initializer itself. */
1183 {
1189 /* If there is a (corresponding) variable or this is the address of a
1190 constant, we only want to return the initializer if an lvalue isn't
1191 required. Evaluate this now if we have not already done so. */
1193 require_lvalue
1197 /* Finally retrieve the initializer if this is deemed valid. */
1200 }
1202 /* But for a constant renaming we couldn't do that incrementally for its
1203 definition because of the need to return an lvalue so, if the present
1204 context doesn't itself require an lvalue, we try again here. */
1208 {
1210 require_lvalue
1215 }
1217 /* The GNAT tree has the type of a function set to its result type, so we
1218 adjust here. Also use the type of the result if the Etype is a subtype
1219 that is nominally unconstrained. Likewise if this is a deferred constant
1220 of a discriminated type whose full view can be elaborated statically, to
1221 avoid problematic conversions to the nominal subtype. But remove any
1222 padding from the resulting type. */
1229 {
1233 }
1238 }
1239 \f
1240 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1241 any statements we generate. */
1243 static tree
1245 {
1248 Node_Id gnat_temp;
1250 /* Do nothing if we are just annotating types and check for (and ignore)
1251 unrecognized pragmas. */
1258 {
1260 /* Do nothing at top level: all such variables are already viewable. */
1267 {
1271 machine_mode mode;
1273 #ifdef ASM_COMMENT_START
1275 #endif
1280 /* Use the value only if it fits into a normal register,
1281 otherwise use the address. */
1290 #ifdef ASM_COMMENT_START
1296 NULL);
1299 #endif
1301 asm_constraint,
1302 NULL_TREE,
1303 tree_cons
1311 }
1318 {
1322 {
1345 }
1346 }
1352 {
1370 }
1380 {
1381 Node_Id gnat_expr;
1382 /* Preserve the location of the pragma. */
1386 diagnostic_t kind;
1391 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1393 {
1395 {
1408 }
1411 }
1413 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1415 {
1417 {
1428 }
1430 /* Deal with optional pattern (but ignore Reason => "..."). */
1432 {
1433 /* pragma Warnings (On | Off, Name) is handled differently. */
1438 }
1439 else
1443 }
1445 else
1448 /* This is the same implementation as in the C family of compilers. */
1450 {
1458 option_index++)
1462 {
1465 }
1466 }
1467 else
1474 }
1479 }
1482 }
1483 \f
1485 /* Check the inlining status of nested function FNDECL in the current context.
1487 If a non-inline nested function is referenced from an inline external
1488 function, we cannot honor both requests at the same time without cloning
1489 the nested function in the current unit since it is private to its unit.
1490 We could inline it as well but it's probably better to err on the side
1491 of too little inlining.
1493 This must be invoked only on nested functions present in the source code
1494 and not on nested functions generated by the compiler, e.g. finalizers,
1495 because they are not marked inline and we don't want them to block the
1496 inlining of the parent function. */
1498 static void
1500 {
1502 && current_function_decl
1505 {
1511 {
1514 }
1515 else
1516 {
1518 fndecl);
1520 }
1524 }
1525 }
1526 \f
1527 /* Return an expression for the length of TYPE, an integral type, computed in
1528 RESULT_TYPE, another integral type.
1530 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1531 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1532 which would only overflow in much rarer cases, for extremely large arrays
1533 we expect never to encounter in practice. Besides, the former computation
1534 required the use of potentially constraining signed arithmetics while the
1535 latter does not. Note that the comparison must be done in the original
1536 base index type in order to avoid any overflow during the conversion. */
1538 static tree
1540 {
1545 tree length
1551 length
1557 }
1559 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1560 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1561 where we should place the result type. ATTRIBUTE is the attribute ID. */
1563 static tree
1565 {
1571 /* ??? If this is an access attribute for a public subprogram to be used in
1572 a dispatch table, do not translate its type as it's useless there and the
1573 parameter types might be incomplete types coming from a limited with. */
1581 else
1585 /* If the input is a NULL_EXPR, make a new one. */
1587 {
1591 }
1594 {
1597 /* These are just conversions since representation clauses for
1598 enumeration types are handled in the front-end. */
1599 {
1605 }
1610 /* These just add or subtract the constant 1 since representation
1611 clauses for enumeration types are handled in the front-end. */
1616 {
1618 gnu_expr
1619 = emit_check
1621 gnu_expr,
1622 attribute == Attr_Pred
1626 }
1628 gnu_result
1636 /* Conversions don't change addresses but can cause us to miss the
1637 COMPONENT_REF case below, so strip them off. */
1641 /* If we are taking 'Address of an unconstrained object, this is the
1642 pointer to the underlying array. */
1646 /* If we are building a static dispatch table, we have to honor
1647 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1648 with the C++ ABI. We do it in the non-static case as well,
1649 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1652 {
1654 /* Descriptors can only be built here for top-level functions. */
1662 /* If we're not going to build the descriptor, we have to retrieve
1663 the one which will be built by the linker (or by the compiler
1664 later if a static chain is requested). */
1666 {
1669 gnu_result);
1671 }
1678 {
1680 {
1684 }
1685 else
1691 elt--;
1692 }
1696 }
1698 /* ... fall through ... */
1704 gnu_result
1711 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1712 don't try to build a trampoline. */
1714 {
1719 }
1721 /* For 'Access, issue an error message if the prefix is a C++ method
1722 since it can use a special calling convention on some platforms,
1723 which cannot be propagated to the access type. */
1728 gnat_node);
1730 /* For other address attributes applied to a nested function,
1731 find an inner ADDR_EXPR and annotate it so that we can issue
1732 a useful warning with -Wtrampolines. */
1734 {
1739 {
1742 /* Also check the inlining status. */
1745 /* Check that we're not violating the No_Implicit_Dynamic_Code
1746 restriction. Be conservative if we don't know anything
1747 about the trampoline strategy for the target. */
1749 }
1750 }
1754 {
1756 tree gnu_obj_type;
1760 /* If this is fat pointer, the object must have been allocated with the
1761 template in front of the array. So compute the template address; do
1762 it by converting to a thin pointer. */
1764 gnu_ptr
1766 (TYPE_OBJECT_RECORD_TYPE
1768 gnu_ptr);
1772 /* If this is a thin pointer, the object must have been allocated with
1773 the template in front of the array. So compute the template address
1774 and return it. */
1776 gnu_ptr
1778 gnu_ptr,
1780 byte_position
1781 (DECL_CHAIN
1785 }
1794 /* Remove NOPs and conversions between original and packable version
1795 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1796 to see if a COMPONENT_REF was involved. */
1801 == RECORD_TYPE
1810 /* Replace an unconstrained array type with the type of the underlying
1811 array. We can't do this with a call to maybe_unconstrained_array
1812 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1813 use the record type that will be used to allocate the object and its
1814 template. */
1816 {
1820 }
1822 /* If we're looking for the size of a field, return the field size. */
1826 /* Otherwise, if the prefix is an object, or if we are looking for
1827 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1828 GCC size of the type. We make an exception for padded objects,
1829 as we do not take into account alignment promotions for the size.
1830 This is in keeping with the object case of gnat_to_gnu_entity. */
1836 {
1837 /* If this is a dereference and we have a special dynamic constrained
1838 subtype on the prefix, use it to compute the size; otherwise, use
1839 the designated subtype. */
1841 {
1842 Node_Id gnat_actual_subtype
1844 tree gnu_ptr_type
1849 {
1850 tree gnu_actual_obj_type
1852 gnu_type
1854 gnu_actual_obj_type,
1857 }
1858 }
1861 }
1863 /* Otherwise, the result is the RM size of the type. */
1864 else
1867 /* Deal with a self-referential size by returning the maximum size for
1868 a type and by qualifying the size with the object otherwise. */
1870 {
1873 else
1875 }
1877 /* If the type contains a template, subtract its size. */
1883 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1891 {
1904 else
1905 {
1910 /* If the default alignment of "double" or larger scalar types is
1911 specifically capped and there is an alignment clause neither
1912 on the type nor on the prefix itself, return the cap. */
1914 is_capped_double
1917 is_capped_double
1919 else
1929 else
1931 }
1934 }
1943 {
1950 else
1953 }
1955 /* ... fall through ... */
1958 {
1966 /* Make sure any implicit dereference gets done. */
1970 /* We treat unconstrained array In parameters specially. We also note
1971 whether we are dereferencing a pointer to unconstrained array. */
1974 {
1976 /* This is the direct case. */
1982 /* This is the indirect case. Note that we need to be sure that
1983 the access value cannot be null as we'll hoist the load. */
1986 {
1989 }
1990 else
1996 }
1998 /* If the prefix is the view conversion of a constrained array to an
1999 unconstrained form, we retrieve the constrained array because we
2000 might not be able to substitute the PLACEHOLDER_EXPR coming from
2001 the conversion. This can occur with the 'Old attribute applied
2002 to a parameter with an unconstrained type, which gets rewritten
2003 into a constrained local variable very late in the game. */
2006 && !CONTAINS_PLACEHOLDER_P
2009 else
2016 {
2018 tree gnu_type_temp;
2024 ;
2027 }
2034 /* When not optimizing, look up the slot associated with the parameter
2035 and the dimension in the cache and create a new one on failure.
2036 Don't do this when the actual subtype needs debug info (this happens
2037 with -gnatD): in elaborate_expression_1, we create variables that
2038 hold the bounds, so caching attributes isn't very interesting and
2039 causes dependency issues between these variables and cached
2040 expressions. */
2045 {
2051 {
2056 }
2057 }
2059 /* Return the cached expression or build a new one. */
2061 {
2063 {
2066 }
2068 gnu_result
2070 }
2073 {
2075 {
2078 }
2080 gnu_result
2082 }
2085 {
2087 {
2090 }
2092 gnu_result
2094 gnu_result_type);
2095 }
2097 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2098 handling. Note that these attributes could not have been used on
2099 an unconstrained array type. */
2102 /* Cache the expression we have just computed. Since we want to do it
2103 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2104 create the temporary in the outermost binding level. We will make
2105 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2106 paths by forcing its evaluation on entry of the function. */
2108 {
2109 gnu_result
2112 {
2128 }
2129 }
2131 /* Otherwise, evaluate it each time it is referenced. */
2132 else
2134 {
2137 /* If we are dereferencing a pointer to unconstrained array, we
2138 need to capture the value because the pointed-to bounds may
2139 subsequently be released. */
2141 gnu_result
2147 /* Set the source location onto the predicate of the condition
2148 but not if the expression is cached to avoid messing up the
2149 debug info. */
2153 gnat_node);
2158 }
2161 }
2168 {
2169 HOST_WIDE_INT bitsize;
2170 HOST_WIDE_INT bitpos;
2171 tree gnu_offset;
2172 tree gnu_field_bitpos;
2173 tree gnu_field_offset;
2174 tree gnu_inner;
2175 machine_mode mode;
2182 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2183 the result is 0. Don't allow 'Bit on a bare component, though. */
2187 {
2190 }
2192 else
2201 {
2209 {
2210 gnu_field_bitpos
2213 gnu_field_offset
2216 }
2217 }
2219 {
2222 }
2223 else
2224 {
2227 }
2230 {
2244 /* ??? Avoid a large unsigned result that will overflow when
2245 converted to the signed universal_integer. */
2248 else
2249 gnu_result
2256 }
2258 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2259 handling. */
2262 }
2266 {
2274 }
2300 /* Note this size cannot be self-referential. */
2310 /* What we want is the offset of the ARRAY field in the record
2311 that the thin pointer designates. */
2319 /* This is just a zero cast to the pointer type for our prefix and
2320 dereferenced. */
2322 gnu_result
2325 integer_zero_node));
2330 {
2337 {
2342 ;
2343 }
2351 && (DECL_BY_COMPONENT_PTR_P
2355 }
2359 /* We treat Model as identical to Machine. This is true for at least
2360 IEEE and some other nice floating-point systems. */
2362 /* ... fall through ... */
2365 /* The trick is to force the compiler to store the result in memory so
2366 that we do not have extra precision used. But do this only when this
2367 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2368 the type is lower than that of the longest floating-point type. */
2377 {
2379 tree field
2389 asm_expr
2401 gnu_result
2405 }
2409 /* This abort means that we have an unimplemented attribute. */
2411 }
2413 /* If this is an attribute where the prefix was unused, force a use of it if
2414 it has a side-effect. But don't do it if the prefix is just an entity
2415 name. However, if an access check is needed, we must do it. See second
2416 example in AARM 11.6(5.e). */
2420 gnu_result
2425 }
2426 \f
2427 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2428 to a GCC tree, which is returned. */
2430 static tree
2432 {
2434 Node_Id gnat_when;
2435 location_t end_locus;
2441 /* The range of values in a case statement is determined by the rules in
2442 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2443 of the expression. One exception arises in the case of a simple name that
2444 is parenthesized. This still has the Etype of the name, but since it is
2445 not a name, para 7 does not apply, and we need to go to the base type.
2446 This is the only case where parenthesization affects the dynamic
2447 semantics (i.e. the range of possible values at run time that is covered
2448 by the others alternative).
2450 Another exception is if the subtype of the expression is non-static. In
2451 that case, we also have to use the base type. */
2457 /* We build a SWITCH_EXPR that contains the code with interspersed
2458 CASE_LABEL_EXPRs for each label. */
2467 {
2469 Node_Id gnat_choice;
2471 /* First compile all the different case choices for the current WHEN
2472 alternative. */
2476 {
2481 {
2496 /* This represents either a subtype range or a static value of
2497 some kind; Ekind says which. */
2499 {
2505 }
2507 /* ... fall through ... */
2519 }
2521 /* Everything should be folded into constants at this point. */
2526 gnat_choice);
2528 }
2530 /* This construct doesn't define a scope so we shouldn't push a binding
2531 level around the statement list. Except that we have always done so
2532 historically and this makes it possible to reduce stack usage. As a
2533 compromise, we keep doing it for case statements, for which this has
2534 never been problematic, but not for case expressions in Ada 2012. */
2536 {
2537 const bool is_case_expression
2539 tree group
2544 {
2549 }
2550 }
2551 }
2553 /* Now emit a definition of the label the cases branch to, if any. */
2560 }
2561 \f
2562 /* Find out whether VAR is an iteration variable of an enclosing loop in the
2563 current function. If so, push a range_check_info structure onto the stack
2564 of this enclosing loop and return it. Otherwise, return NULL. */
2568 {
2584 i--)
2589 {
2593 }
2596 }
2598 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2599 false, or the maximum value if MAX is true, of TYPE. */
2601 static bool
2603 {
2610 val = (max
2619 else
2621 }
2623 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2624 If REVERSE is true, minimum value is taken as maximum value. */
2628 {
2630 }
2632 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2633 If REVERSE is true, maximum value is taken as minimum value. */
2637 {
2639 }
2641 /* Return true if VAL1 can be lower than VAL2. */
2643 static bool
2645 {
2659 }
2661 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2662 to a GCC tree, which is returned. */
2664 static tree
2666 {
2673 tree gnu_result;
2675 /* Push the loop_info structure associated with the LOOP_STMT. */
2678 /* Set location information for statement and end label. */
2684 /* Save the statement for later reuse. */
2687 /* Set the condition under which the loop must keep going.
2688 For the case "LOOP .... END LOOP;" the condition is always true. */
2690 ;
2692 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2697 /* Otherwise we have an iteration scheme and the condition is given by the
2698 bounds of the subtype of the iteration variable. */
2699 else
2700 {
2714 /* We must disable modulo reduction for the iteration variable, if any,
2715 in order for the loop comparison to be effective. */
2717 {
2723 }
2724 else
2725 {
2731 }
2733 /* We use two different strategies to translate the loop, depending on
2734 whether optimization is enabled.
2736 If it is, we generate the canonical loop form expected by the loop
2737 optimizer and the loop vectorizer, which is the do-while form:
2739 ENTRY_COND
2740 loop:
2741 TOP_UPDATE
2742 BODY
2743 BOTTOM_COND
2744 GOTO loop
2746 This avoids an implicit dependency on loop header copying and makes
2747 it possible to turn BOTTOM_COND into an inequality test.
2749 If optimization is disabled, loop header copying doesn't come into
2750 play and we try to generate the loop form with the fewer conditional
2751 branches. First, the default form, which is:
2753 loop:
2754 TOP_COND
2755 BODY
2756 BOTTOM_UPDATE
2757 GOTO loop
2759 It should catch most loops with constant ending point. Then, if we
2760 cannot, we try to generate the shifted form:
2762 loop:
2763 TOP_COND
2764 TOP_UPDATE
2765 BODY
2766 GOTO loop
2768 which should catch loops with constant starting point. Otherwise, if
2769 we cannot, we generate the fallback form:
2771 ENTRY_COND
2772 loop:
2773 BODY
2774 BOTTOM_COND
2775 BOTTOM_UPDATE
2776 GOTO loop
2778 which works in all cases. */
2781 {
2782 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2783 overflow. */
2785 ;
2787 /* Otherwise, use the do-while form with the help of a special
2788 induction variable in the unsigned version of the base type
2789 or the unsigned version of the size type, whichever is the
2790 largest, in order to have wrap-around arithmetics for it. */
2791 else
2792 {
2795 gnu_base_type
2797 else
2804 }
2806 gnu_first
2808 gnu_one_node);
2811 }
2812 else
2813 {
2814 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2816 ;
2818 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2819 GNU_LAST-1 does. */
2822 {
2823 gnu_first
2825 gnu_one_node);
2826 gnu_last
2828 gnu_one_node);
2830 }
2832 /* Otherwise, use the fallback form. */
2833 else
2835 }
2837 /* If we use the BOTTOM_COND, we can turn the test into an inequality
2838 test but we may have to add ENTRY_COND to protect the empty loop. */
2840 {
2843 {
2844 gnu_cond_expr
2850 }
2851 }
2853 /* Open a new nesting level that will surround the loop to declare the
2854 iteration variable. */
2858 /* If we use the special induction variable, create it and set it to
2859 its initial value. Morever, the regular iteration variable cannot
2860 itself be initialized, lest the initial value wrapped around. */
2862 {
2863 gnu_loop_iv
2867 }
2868 else
2871 /* Declare the iteration variable and set it to its initial value. */
2876 {
2879 }
2882 /* Do all the arithmetics in the base type. */
2885 /* Set either the top or bottom exit condition. */
2889 gnu_last);
2890 else
2893 gnu_last);
2895 /* Set either the top or bottom update statement and give it the source
2896 location of the iteration for better coverage info. */
2898 {
2899 gnu_stmt
2906 gnu_stmt
2908 gnu_loop_iv);
2912 }
2913 else
2914 {
2915 gnu_stmt
2921 }
2922 }
2924 /* If the loop was named, have the name point to this loop. In this case,
2925 the association is not a DECL node, but the end label of the loop. */
2929 /* Make the loop body into its own block, so any allocated storage will be
2930 released every iteration. This is needed for stack allocation. */
2935 /* If we have an iteration scheme, then we are in a statement group. Add
2936 the LOOP_STMT to it, finish it and make it the "loop". */
2938 {
2943 /* First, if we have computed a small number of invariant conditions for
2944 range checks applied to the iteration variable, then initialize these
2945 conditions in front of the loop. Otherwise, leave them set to true.
2947 ??? The heuristics need to be improved, by taking into account the
2948 following datapoints:
2949 - loop unswitching is disabled for big loops. The cap is the
2950 parameter PARAM_MAX_UNSWITCH_INSNS (50).
2951 - loop unswitching can only be applied a small number of times
2952 to a given loop. The cap is PARAM_MAX_UNSWITCH_LEVEL (3).
2953 - the front-end quickly generates useless or redundant checks
2954 that can be entirely optimized away in the end. */
2958 i++)
2959 {
2960 tree low_ok
2967 tree high_ok
2974 tree range_ok
2982 }
2987 }
2989 /* If we have an outer COND_EXPR, that's our result and this loop is its
2990 "true" statement. Otherwise, the result is the LOOP_STMT. */
2992 {
2996 }
2997 else
3003 }
3004 \f
3005 /* This page implements a form of Named Return Value optimization modelled
3006 on the C++ optimization of the same name. The main difference is that
3007 we disregard any semantical considerations when applying it here, the
3008 counterpart being that we don't try to apply it to semantically loaded
3009 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3011 We consider a function body of the following GENERIC form:
3013 return_type R1;
3014 [...]
3015 RETURN_EXPR [<retval> = ...]
3016 [...]
3017 RETURN_EXPR [<retval> = R1]
3018 [...]
3019 return_type Ri;
3020 [...]
3021 RETURN_EXPR [<retval> = ...]
3022 [...]
3023 RETURN_EXPR [<retval> = Ri]
3024 [...]
3026 and we try to fulfill a simple criterion that would make it possible to
3027 replace one or several Ri variables with the RESULT_DECL of the function.
3029 The first observation is that RETURN_EXPRs that don't directly reference
3030 any of the Ri variables on the RHS of their assignment are transparent wrt
3031 the optimization. This is because the Ri variables aren't addressable so
3032 any transformation applied to them doesn't affect the RHS; moreover, the
3033 assignment writes the full <retval> object so existing values are entirely
3034 discarded.
3036 This property can be extended to some forms of RETURN_EXPRs that reference
3037 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3038 case, in particular when function calls are involved.
3040 Therefore the algorithm is as follows:
3042 1. Collect the list of candidates for a Named Return Value (Ri variables
3043 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3044 other expressions on the RHS of such assignments.
3046 2. Prune the members of the first list (candidates) that are referenced
3047 by a member of the second list (expressions).
3049 3. Extract a set of candidates with non-overlapping live ranges from the
3050 first list. These are the Named Return Values.
3052 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3053 Named Return Values in the function with the RESULT_DECL.
3055 If the function returns an unconstrained type, things are a bit different
3056 because the anonymous return object is allocated on the secondary stack
3057 and RESULT_DECL is only a pointer to it. Each return object can be of a
3058 different size and is allocated separately so we need not care about the
3059 aforementioned overlapping issues. Therefore, we don't collect the other
3060 expressions and skip step #2 in the algorithm. */
3062 struct nrv_data
3063 {
3064 bitmap nrv;
3065 tree result;
3066 Node_Id gnat_ret;
3068 };
3070 /* Return true if T is a Named Return Value. */
3074 {
3076 }
3078 /* Helper function for walk_tree, used by finalize_nrv below. */
3080 static tree
3082 {
3086 /* No need to walk into types or decls. */
3094 }
3096 /* Prune Named Return Values in BLOCK and return true if there is still a
3097 Named Return Value in BLOCK or one of its sub-blocks. */
3099 static bool
3101 {
3103 tree t;
3105 /* First recurse on the sub-blocks. */
3109 /* Then make sure to keep at most one NRV per block. */
3112 {
3115 else
3117 }
3120 }
3122 /* Helper function for walk_tree, used by finalize_nrv below. */
3124 static tree
3126 {
3130 /* No need to walk into types. */
3134 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3135 nop, but differs from using NULL_TREE in that it indicates that we care
3136 about the value of the RESULT_DECL. */
3139 {
3142 /* If this is the temporary created for a return value with variable
3143 size in Call_to_gnu, we replace the RHS with the init expression. */
3148 {
3151 }
3152 else
3155 /* Strip useless conversions around the return value. */
3160 {
3163 else
3165 }
3166 }
3168 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3169 if needed. */
3172 {
3176 {
3181 }
3182 else
3186 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3189 /* ??? Kludge to avoid an assertion failure during inlining. */
3192 }
3194 /* And replace all uses of NRVs with the RESULT_DECL. */
3198 /* Avoid walking into the same tree more than once. Unfortunately, we
3199 can't just use walk_tree_without_duplicates because it would only
3200 call us for the first occurrence of NRVs in the function body. */
3205 }
3207 /* Likewise, but used when the function returns an unconstrained type. */
3209 static tree
3211 {
3215 /* No need to walk into types. */
3219 /* We need to see the DECL_EXPR of NRVs before any other references so we
3220 walk the body of BIND_EXPR before walking its variables. */
3224 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3225 return value built by the allocator instead of the whole construct. */
3228 {
3231 /* This is the construct returned by the allocator. */
3234 {
3236 ret_val
3239 else
3241 }
3243 /* Strip useless conversions around the return value. */
3248 /* Strip unpadding around the return value. */
3253 /* Assign the new return value to the RESULT_DECL. */
3257 }
3259 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3260 into a new variable. */
3263 {
3270 /* Create an artificial context to build the allocation. */
3275 /* This will return a COMPOUND_EXPR with the allocation in the first
3276 arm and the final return value in the second arm. */
3283 /* The new variable is built as a reference to the allocated space. */
3284 new_var
3290 {
3291 /* The new initial value is a COMPOUND_EXPR with the allocation in
3292 the first arm and the value of P_ARRAY in the second arm. */
3298 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3306 }
3307 else
3308 {
3309 /* The new initial value is just the allocation. */
3312 }
3316 /* Destroy the artificial context and insert the new statements. */
3321 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3326 /* Save the new return value and the dereference of NEW_VAR. */
3330 /* ??? Kludge to avoid messing up during inlining. */
3332 }
3334 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3338 /* Avoid walking into the same tree more than once. Unfortunately, we
3339 can't just use walk_tree_without_duplicates because it would only
3340 call us for the first occurrence of NRVs in the function body. */
3345 }
3347 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3348 contains the candidates for Named Return Value and OTHER is a list of
3349 the other return values. GNAT_RET is a representative return node. */
3351 static void
3353 {
3356 walk_tree_fn func;
3358 tree iter;
3360 /* We shouldn't be applying the optimization to return types that we aren't
3361 allowed to manipulate freely. */
3364 /* Prune the candidates that are referenced by other return values. */
3373 /* Prune also the candidates that are referenced by nested functions. */
3381 /* Extract a set of NRVs with non-overlapping live ranges. */
3385 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3392 else
3396 }
3398 /* Return true if RET_VAL can be used as a Named Return Value for the
3399 anonymous return object RET_OBJ. */
3401 static bool
3403 {
3423 }
3425 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3426 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3427 around RESULT_OBJ, which may be null in this case. */
3429 static tree
3431 {
3432 tree result_expr;
3435 {
3436 /* The gimplifier explicitly enforces the following invariant:
3438 RETURN_EXPR
3439 |
3440 MODIFY_EXPR
3441 / \
3442 / \
3443 RET_OBJ ...
3445 As a consequence, type consistency dictates that we use the type
3446 of the RET_OBJ as the operation type. */
3449 /* Convert the right operand to the operation type. Note that it's the
3450 same transformation as in the MODIFY_EXPR case of build_binary_op,
3451 with the assumption that the type cannot involve a placeholder. */
3457 /* If the function returns an aggregate type, find out whether this is
3458 a candidate for Named Return Value. If so, record it. Otherwise,
3459 if this is an expression of some kind, record it elsewhere. */
3465 {
3466 /* Recognize the temporary created for a return value with variable
3467 size in Call_to_gnu. We want to eliminate it if possible. */
3474 /* Strip useless conversions around the return value. */
3478 /* Now apply the test to the return value. */
3480 {
3484 }
3486 /* Note that we need not care about CONSTRUCTORs here, as they are
3487 totally transparent given the read-compose-write semantics of
3488 assignments from CONSTRUCTORs. */
3491 }
3492 }
3493 else
3497 }
3498 \f
3499 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3500 don't return anything. */
3502 static void
3504 {
3505 /* Defining identifier of a parameter to the subprogram. */
3506 Entity_Id gnat_param;
3507 /* The defining identifier for the subprogram body. Note that if a
3508 specification has appeared before for this body, then the identifier
3509 occurring in that specification will also be a defining identifier and all
3510 the calls to this subprogram will point to that specification. */
3511 Entity_Id gnat_subprog_id
3514 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3515 tree gnu_subprog_decl;
3516 /* Its RESULT_DECL node. */
3517 tree gnu_result_decl;
3518 /* Its FUNCTION_TYPE node. */
3519 tree gnu_subprog_type;
3520 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3521 tree gnu_cico_list;
3522 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3524 tree gnu_result;
3525 location_t locus;
3529 /* If this is a generic object or if it has been eliminated,
3530 ignore it. */
3536 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3537 the already-elaborated tree node. However, if this subprogram had its
3538 elaboration deferred, we will already have made a tree node for it. So
3539 treat it as not being defined in that case. Such a subprogram cannot
3540 have an address clause or a freeze node, so this test is safe, though it
3541 does disable some otherwise-useful error checking. */
3542 gnu_subprog_decl
3552 /* If the function returns by invisible reference, make it explicit in the
3553 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3555 {
3559 }
3561 /* Set the line number in the decl to correspond to that of the body. */
3565 /* Initialize the information structure for the function. */
3574 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3575 properly copied out by the return statement. We do this by making a new
3576 block and converting any return into a goto to a label at the end of the
3577 block. */
3579 {
3588 /* If this is a function with copy-in/copy-out parameters and which does
3589 not return by invisible reference, we also need a variable for the
3590 return value to be placed. */
3592 {
3593 tree gnu_return_type
3596 gnu_return_var
3601 }
3605 /* See whether there are parameters for which we don't have a GCC tree
3606 yet. These must be Out parameters. Make a VAR_DECL for them and
3607 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3608 We can match up the entries because TYPE_CI_CO_LIST is in the order
3609 of the parameters. */
3614 {
3616 tree gnu_decl;
3618 /* Skip any entries that have been already filled in; they must
3619 correspond to In Out parameters. */
3623 /* Do any needed dereferences for by-ref objects. */
3629 /* Do any needed references for padded types. */
3632 }
3633 }
3634 else
3637 /* Get a tree corresponding to the code for the subprogram. */
3643 /* Generate the code of the subprogram itself. A return statement will be
3644 present and any Out parameters will be handled there. */
3649 /* If we populated the parameter attributes cache, we need to make sure that
3650 the cached expressions are evaluated on all the possible paths leading to
3651 their uses. So we force their evaluation on entry of the function. */
3654 {
3661 {
3668 }
3674 }
3676 /* If we are dealing with a return from an Ada procedure with parameters
3677 passed by copy-in/copy-out, we need to return a record containing the
3678 final values of these parameters. If the list contains only one entry,
3679 return just that entry though.
3681 For a full description of the copy-in/copy-out parameter mechanism, see
3682 the part of the gnat_to_gnu_entity routine dealing with the translation
3683 of subprograms.
3685 We need to make a block that contains the definition of that label and
3686 the copying of the return value. It first contains the function, then
3687 the label and copy statement. */
3689 {
3690 const Node_Id gnat_end_label
3699 /* If this is a function which returns by invisible reference, the
3700 return value has already been dealt with at the return statements,
3701 so we only need to indirectly copy out the parameters. */
3703 {
3704 tree gnu_ret_deref
3706 tree t;
3711 {
3712 tree gnu_field_deref
3718 }
3719 }
3721 /* Otherwise, if this is a procedure or a function which does not return
3722 by invisible reference, we can do a direct block-copy out. */
3723 else
3724 {
3725 tree gnu_retval;
3729 else
3730 gnu_retval
3732 gnu_cico_list);
3736 }
3740 }
3744 /* Attempt setting the end_locus of our GCC body tree, typically a
3745 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3746 declaration tree. */
3750 /* On SEH targets, install an exception handler around the main entry
3751 point to catch unhandled exceptions. */
3754 {
3755 tree t;
3756 tree etype;
3768 }
3772 /* Finally annotate the parameters and disconnect the trees for parameters
3773 that we have turned into variables since they are now unusable. */
3777 {
3786 }
3788 /* Disconnect the variable created for the return value. */
3792 /* If the function returns an aggregate type and we have candidates for
3793 a Named Return Value, finalize the optimization. */
3795 {
3802 }
3804 /* If this is an inlined external function that has been marked uninlinable,
3805 drop the body and stop there. Otherwise compile the body. */
3808 else
3810 }
3811 \f
3812 /* Return true if GNAT_NODE requires atomic synchronization. */
3814 static bool
3816 {
3818 Node_Kind kind;
3821 /* First, scan the node to find the Atomic_Sync_Required flag. */
3824 {
3827 }
3830 {
3842 }
3844 /* Then, scan the parent to find out cases where the flag is irrelevant. */
3847 {
3850 /* Do not mess up machine code insertions. */
3856 /* Do not generate a function call as a renamed object. */
3861 }
3864 }
3865 \f
3866 /* Create a temporary variable with PREFIX and TYPE, and return it. */
3868 static tree
3870 {
3878 }
3880 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
3881 Put the initialization statement into GNU_INIT_STMT and annotate it with
3882 the SLOC of GNAT_NODE. Return the temporary variable. */
3884 static tree
3886 Node_Id gnat_node)
3887 {
3894 }
3896 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
3897 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
3898 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
3899 If GNU_TARGET is non-null, this must be a function call on the RHS of a
3900 N_Assignment_Statement and the result is to be placed into that object.
3901 If, in addition, ATOMIC_SYNC is true, then the assignment to GNU_TARGET
3902 requires atomic synchronization. */
3904 static tree
3907 {
3910 /* The GCC node corresponding to the GNAT subprogram name. This can either
3911 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
3912 or an indirect reference expression (an INDIRECT_REF node) pointing to a
3913 subprogram. */
3915 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
3917 /* The return type of the FUNCTION_TYPE. */
3928 Entity_Id gnat_formal;
3929 Node_Id gnat_actual;
3933 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
3934 all our args first. */
3936 {
3946 {
3949 }
3952 }
3954 /* For a call to a nested function, check the inlining status. */
3959 /* The only way we can be making a call via an access type is if Name is an
3960 explicit dereference. In that case, get the list of formal args from the
3961 type the access type is pointing to. Otherwise, get the formals from the
3962 entity being called. */
3966 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
3968 else
3971 /* The lifetime of the temporaries created for the call ends right after the
3972 return value is copied, so we can give them the scope of the elaboration
3973 routine at top level. */
3975 {
3978 }
3980 /* First, create the temporary for the return value when:
3982 1. There is no target and the function has copy-in/copy-out parameters,
3983 because we need to preserve the return value before copying back the
3984 parameters.
3986 2. There is no target and this is not an object declaration, and the
3987 return type has variable size, because in these cases the gimplifier
3988 cannot create the temporary.
3990 3. There is a target and it is a slice or an array with fixed size,
3991 and the return type has variable size, because the gimplifier
3992 doesn't handle these cases.
3994 This must be done before we push a binding level around the call, since
3995 we will pop it before copying the return value. */
3998 || (!gnu_target
4001 || (gnu_target
4009 /* Create the list of the actual parameters as GCC expects it, namely a
4010 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4011 is an expression and the TREE_PURPOSE field is null. But skip Out
4012 parameters not passed by reference and that need not be copied in. */
4017 {
4022 const bool is_true_formal_parm
4024 const bool is_by_ref_formal_parm
4025 = is_true_formal_parm
4028 /* In the Out or In Out case, we must suppress conversions that yield
4029 an lvalue but can nevertheless cause the creation of a temporary,
4030 because we need the real object in this case, either to pass its
4031 address if it's passed by reference or as target of the back copy
4032 done after the call if it uses the copy-in/copy-out mechanism.
4033 We do it in the In case too, except for an unchecked conversion
4034 to an elementary type or a constrained composite type because it
4035 alone can cause the actual to be misaligned and the addressability
4036 test is applied to the real object. */
4037 const bool suppress_type_conversion
4044 Node_Id gnat_name = suppress_type_conversion
4047 tree gnu_actual;
4049 /* If it's possible we may need to use this expression twice, make sure
4050 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4051 to force side-effects before the call.
4052 ??? This is more conservative than we need since we don't need to do
4053 this for pass-by-ref with no conversion. */
4057 /* If we are passing a non-addressable parameter by reference, pass the
4058 address of a copy. In the Out or In Out case, set up to copy back
4059 out after the call. */
4063 {
4067 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4068 but sort of an instantiation for them. */
4070 ;
4072 /* If the type is passed by reference, a copy is not allowed. */
4075 gnat_actual);
4077 /* For users of Starlet we issue a warning because the interface
4078 apparently assumes that by-ref parameters outlive the procedure
4079 invocation. The code still will not work as intended, but we
4080 cannot do much better since low-level parts of the back-end
4081 would allocate temporaries at will because of the misalignment
4082 if we did not do so here. */
4084 {
4085 post_error
4087 post_error_ne
4091 gnat_formal);
4092 }
4094 /* If the actual type of the object is already the nominal type,
4095 we have nothing to do, except if the size is self-referential
4096 in which case we'll remove the unpadding below. */
4099 ;
4101 /* Otherwise remove the unpadding from all the objects. */
4103 && TYPE_IS_PADDING_P
4107 /* Otherwise convert to the nominal type of the object if needed.
4108 There are several cases in which we need to make the temporary
4109 using this type instead of the actual type of the object when
4110 they are distinct, because the expectations of the callee would
4111 otherwise not be met:
4112 - if it's a justified modular type,
4113 - if the actual type is a smaller form of it,
4114 - if it's a smaller form of the actual type. */
4118 gnu_name_type)))
4124 /* If this is an In Out or Out parameter and we're returning a value,
4125 we need to create a temporary for the return value because we must
4126 preserve it before copying back at the very end. */
4130 /* If we haven't pushed a binding level, push a new one. This will
4131 narrow the lifetime of the temporary we are about to make as much
4132 as possible. The drawback is that we'd need to create a temporary
4133 for the return value, if any (see comment before the loop). So do
4134 it only when this temporary was already created just above. */
4136 {
4140 }
4142 /* Create an explicit temporary holding the copy. */
4143 gnu_temp
4146 /* But initialize it on the fly like for an implicit temporary as
4147 we aren't necessarily having a statement list. */
4149 gnu_temp);
4151 /* Set up to move the copy back to the original if needed. */
4153 {
4154 /* If the original is a COND_EXPR whose first arm isn't meant to
4155 be further used, just deal with the second arm. This is very
4156 likely the conditional expression built for a check. */
4159 && integer_zerop
4163 gnu_stmt
4168 }
4169 }
4171 /* Start from the real object and build the actual. */
4174 /* If this is an atomic access of an In or In Out parameter for which
4175 synchronization is required, build the atomic load. */
4177 && !is_by_ref_formal_parm
4182 /* If this was a procedure call, we may not have removed any padding.
4183 So do it here for the part we will use as an input, if any. */
4186 gnu_actual
4189 /* Put back the conversion we suppressed above in the computation of the
4190 real object. And even if we didn't suppress any conversion there, we
4191 may have suppressed a conversion to the Etype of the actual earlier,
4192 since the parent is a procedure call, so put it back here. */
4195 gnu_actual
4198 else
4199 gnu_actual
4202 /* Make sure that the actual is in range of the formal's type. */
4205 gnu_actual
4208 /* Unless this is an In parameter, we must remove any justified modular
4209 building from GNU_NAME to get an lvalue. */
4214 gnu_name
4217 /* First see if the parameter is passed by reference. */
4219 {
4221 {
4222 /* In Out or Out parameters passed by reference don't use the
4223 copy-in/copy-out mechanism so the address of the real object
4224 must be passed to the function. */
4227 /* If we have a padded type, be sure we've removed padding. */
4230 gnu_actual);
4232 /* If we have the constructed subtype of an aliased object
4233 with an unconstrained nominal subtype, the type of the
4234 actual includes the template, although it is formally
4235 constrained. So we need to convert it back to the real
4236 constructed subtype to retrieve the constrained part
4237 and takes its address. */
4243 gnu_actual);
4244 }
4246 /* There is no need to convert the actual to the formal's type before
4247 taking its address. The only exception is for unconstrained array
4248 types because of the way we build fat pointers. */
4250 {
4251 /* Put back a view conversion for In Out or Out parameters. */
4254 gnu_actual);
4256 }
4258 /* The symmetry of the paths to the type of an entity is broken here
4259 since arguments don't know that they will be passed by ref. */
4262 }
4264 /* Then see if the parameter is an array passed to a foreign convention
4265 subprogram. */
4267 {
4273 {
4276 }
4278 /* Take the address of the object and convert to the proper pointer
4279 type. We'd like to actually compute the address of the beginning
4280 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4281 possibility that the ARRAY_REF might return a constant and we'd be
4282 getting the wrong address. Neither approach is exactly correct,
4283 but this is the most likely to work in all cases. */
4285 }
4287 /* Otherwise the parameter is passed by copy. */
4288 else
4289 {
4290 tree gnu_size;
4295 /* If we didn't create a PARM_DECL for the formal, this means that
4296 it is an Out parameter not passed by reference and that need not
4297 be copied in. In this case, the value of the actual need not be
4298 read. However, we still need to make sure that its side-effects
4299 are evaluated before the call, so we evaluate its address. */
4301 {
4303 {
4306 }
4308 }
4312 /* If this is 'Null_Parameter, pass a zero even though we are
4313 dereferencing it. */
4319 gnu_actual
4323 integer_zero_node),
4325 else
4327 }
4330 }
4332 gnu_call
4336 /* If we have created a temporary for the return value, initialize it. */
4338 {
4339 tree gnu_stmt
4344 }
4346 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4347 unpack the valued returned from the function into the In Out or Out
4348 parameters. We deal with the function return (if this is an Ada
4349 function) below. */
4351 {
4352 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4353 copy-out parameters. */
4357 /* The call sequence must contain one and only one call, even though the
4358 function is pure. Save the result into a temporary if needed. */
4360 {
4362 {
4363 tree gnu_stmt;
4364 /* If we haven't pushed a binding level, push a new one. This
4365 will narrow the lifetime of the temporary we are about to
4366 make as much as possible. */
4368 {
4372 }
4373 gnu_call
4376 }
4379 }
4381 /* The first entry is for the actual return value if this is a
4382 function, so skip it. */
4388 else
4395 /* If we are dealing with a copy-in/copy-out parameter, we must
4396 retrieve its value from the record returned in the call. */
4402 {
4403 /* Get the value to assign to this Out or In Out parameter. It is
4404 either the result of the function if there is only a single such
4405 parameter or the appropriate field from the record returned. */
4406 tree gnu_result
4408 ? gnu_call
4412 /* If the actual is a conversion, get the inner expression, which
4413 will be the real destination, and convert the result to the
4414 type of the actual parameter. */
4415 tree gnu_actual
4418 /* If the result is a padded type, remove the padding. */
4420 gnu_result
4422 gnu_result);
4424 /* If the actual is a type conversion, the real target object is
4425 denoted by the inner Expression and we need to convert the
4426 result to the associated type.
4427 We also need to convert our gnu assignment target to this type
4428 if the corresponding GNU_NAME was constructed from the GNAT
4429 conversion node and not from the inner Expression. */
4431 {
4432 gnu_result
4433 = convert_with_check
4441 }
4443 /* Unchecked conversions as actuals for Out parameters are not
4444 allowed in user code because they are not variables, but do
4445 occur in front-end expansions. The associated GNU_NAME is
4446 always obtained from the inner expression in such cases. */
4449 gnu_result,
4451 else
4452 {
4454 gnu_result
4456 gnat_actual);
4461 }
4465 else
4472 }
4473 }
4475 /* If this is a function call, the result is the call expression unless a
4476 target is specified, in which case we copy the result into the target
4477 and return the assignment statement. */
4479 {
4480 /* If this is a function with copy-in/copy-out parameters, extract the
4481 return value from it and update the return type. */
4483 {
4488 }
4490 /* If the function returns an unconstrained array or by direct reference,
4491 we have to dereference the pointer. */
4497 {
4501 /* If range check is needed, emit code to generate it. */
4503 gnu_call
4505 gnat_parent);
4507 /* ??? If the return type has variable size, then force the return
4508 slot optimization as we would not be able to create a temporary.
4509 Likewise if it was unconstrained as we would copy too much data.
4510 That's what has been done historically. */
4513 && CONTAINS_PLACEHOLDER_P
4516 else
4521 else
4522 gnu_call
4526 }
4527 else
4529 }
4531 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4532 parameters, the result is just the call statement. */
4536 /* Finally, add the copy back statements, if any. */
4542 /* If we have pushed a binding level, pop it and finish up the enclosing
4543 statement group. */
4545 {
4549 }
4551 /* Otherwise, retrieve the statement list, if any. */
4555 /* Otherwise, just return the call expression. */
4556 else
4559 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4560 But first simplify if we have only one statement in the list. */
4562 {
4566 gnu_result
4568 }
4571 }
4572 \f
4573 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4574 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4576 static tree
4578 {
4581 /* If just annotating, ignore all EH and cleanups. */
4585 bool setjmp_longjmp
4591 tree gnu_result;
4592 tree gnu_expr;
4593 Node_Id gnat_temp;
4594 /* Node providing the sloc for the cleanup actions. */
4597 gnat_node);
4599 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4600 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4601 add_cleanup, and when we leave the binding, end_stmt_group will create
4602 the TRY_FINALLY_EXPR.
4604 ??? The region level calls down there have been specifically put in place
4605 for a ZCX context and currently the order in which things are emitted
4606 (region/handlers) is different from the SJLJ case. Instead of putting
4607 other calls with different conditions at other places for the SJLJ case,
4608 it seems cleaner to reorder things for the SJLJ case and generalize the
4609 condition to make it not ZCX specific.
4611 If there are any exceptions or cleanup processing involved, we need an
4612 outer statement group (for Setjmp_Longjmp) and binding level. */
4614 {
4617 }
4619 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
4620 area for address of previous buffer. Do this first since we need to have
4621 the setjmp buf known for any decls in this block. */
4623 {
4624 gnu_jmpsave_decl
4626 jmpbuf_ptr_type,
4631 /* The __builtin_setjmp receivers will immediately reinstall it. Now
4632 because of the unstructured form of EH used by setjmp_longjmp, there
4633 might be forward edges going to __builtin_setjmp receivers on which
4634 it is uninitialized, although they will never be actually taken. */
4636 gnu_jmpbuf_decl
4638 jmpbuf_type,
4639 NULL_TREE,
4645 /* When we exit this block, restore the saved value. */
4647 gnat_cleanup_loc_node);
4648 }
4650 /* If we are to call a function when exiting this block, add a cleanup
4651 to the binding level we made above. Note that add_cleanup is FIFO
4652 so we must register this cleanup after the EH cleanup just above. */
4655 gnat_cleanup_loc_node);
4657 /* Now build the tree for the declarations and statements inside this block.
4658 If this is SJLJ, set our jmp_buf as the current buffer. */
4662 {
4665 gnu_jmpbuf_decl));
4668 }
4674 /* Generate code for each statement in the block. */
4682 /* Now generate code for the two exception models, if either is relevant for
4683 this block. */
4685 {
4687 tree gnu_handler;
4689 /* Make a binding level for the exception handling declarations and code
4690 and set up gnu_except_ptr_stack for the handlers to use. */
4701 /* Generate code for each handler. The N_Exception_Handler case does the
4702 real work and returns a COND_EXPR for each handler, which we chain
4703 together here. */
4706 {
4709 /* If this is the first one, set it as the outer one. Otherwise,
4710 point the "else" part of the previous handler to us. Then point
4711 to our "else" part. */
4714 else
4718 }
4720 /* If none of the exception handlers did anything, re-raise but do not
4721 defer abortion. */
4724 set_expr_location_from_node
4730 else
4733 /* End the binding level dedicated to the exception handlers and get the
4734 whole statement group. */
4739 /* If the setjmp returns 1, we restore our incoming longjmp value and
4740 then check the handlers. */
4743 gnu_jmpsave_decl),
4744 gnat_node);
4748 /* This block is now "if (setjmp) ... <handlers> else <block>". */
4750 (build_call_n_expr
4753 gnu_jmpbuf_decl))),
4755 }
4757 {
4758 tree gnu_handlers;
4759 location_t locus;
4761 /* First make a block containing the handlers. */
4769 /* Now make the TRY_CATCH_EXPR for the block. */
4772 /* Set a location. We need to find a unique location for the dispatching
4773 code, otherwise we can get coverage or debugging issues. Try with
4774 the location of the end label. */
4778 else
4779 /* Clear column information so that the exception handler of an
4780 implicit transient block does not incorrectly inherit the slocs
4781 of a decision, which would otherwise confuse control flow based
4782 coverage analysis tools. */
4784 }
4785 else
4788 /* Now close our outer block, if we had to make one. */
4790 {
4794 }
4797 }
4798 \f
4799 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4800 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
4801 exception handling. */
4803 static tree
4805 {
4806 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
4807 an "if" statement to select the proper exceptions. For "Others", exclude
4808 exceptions where Handled_By_Others is nonzero unless the All_Others flag
4809 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
4812 Node_Id gnat_temp;
4816 {
4817 tree this_choice;
4820 {
4823 else
4824 this_choice
4825 = build_binary_op
4827 convert
4829 build_component_ref
4830 (build_unary_op
4835 integer_zero_node);
4836 }
4840 {
4842 tree gnu_expr;
4844 /* Exception may be a renaming. Recover original exception which is
4845 the one elaborated and registered. */
4851 this_choice
4852 = build_binary_op
4857 }
4858 else
4863 }
4866 }
4867 \f
4868 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4869 to a GCC tree, which is returned. This is the variant for ZCX. */
4871 static tree
4873 {
4876 Node_Id gnat_temp;
4878 /* We build a TREE_LIST of nodes representing what exception types this
4879 handler can catch, with special cases for others and all others cases.
4881 Each exception type is actually identified by a pointer to the exception
4882 id, or to a dummy object for "others" and "all others". */
4885 {
4889 {
4892 }
4895 {
4898 /* Exception may be a renaming. Recover original exception which is
4899 the one elaborated and registered. */
4905 }
4906 else
4909 /* The GCC interface expects NULL to be passed for catch all handlers, so
4910 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
4911 is integer_zero_node. It would not work, however, because GCC's
4912 notion of "catch all" is stronger than our notion of "others". Until
4913 we correctly use the cleanup interface as well, doing that would
4914 prevent the "all others" handlers from being seen, because nothing
4915 can be caught beyond a catch all from GCC's point of view. */
4917 }
4922 /* Expand a call to the begin_handler hook at the beginning of the handler,
4923 and arrange for a call to the end_handler hook to occur on every possible
4924 exit path.
4926 The hooks expect a pointer to the low level occurrence. This is required
4927 for our stack management scheme because a raise inside the handler pushes
4928 a new occurrence on top of the stack, which means that this top does not
4929 necessarily match the occurrence this handler was dealing with.
4931 __builtin_eh_pointer references the exception occurrence being
4932 propagated. Upon handler entry, this is the exception for which the
4933 handler is triggered. This might not be the case upon handler exit,
4934 however, as we might have a new occurrence propagated by the handler's
4935 body, and the end_handler hook called as a cleanup in this context.
4937 We use a local variable to retrieve the incoming value at handler entry
4938 time, and reuse it to feed the end_handler hook's argument at exit. */
4940 gnu_current_exc_ptr
4950 gnu_incoming_exc_ptr),
4951 gnat_node);
4953 /* Declare and initialize the choice parameter, if present. */
4955 {
4956 tree gnu_param
4962 gnu_incoming_exc_ptr));
4963 }
4965 /* We don't have an End_Label at hand to set the location of the cleanup
4966 actions, so we use that of the exception handler itself instead. */
4968 gnat_node);
4974 return
4976 }
4977 \f
4978 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
4980 static void
4982 {
4987 Entity_Id gnat_entity;
4988 Node_Id gnat_pragma;
4989 /* Make the decl for the elaboration procedure. */
4990 tree gnu_elab_proc_decl
4991 = create_subprog_decl
4994 gnat_unit);
5000 /* Initialize the information structure for the function. */
5009 /* For a body, first process the spec if there is one. */
5015 {
5022 }
5024 /* Then process any pragmas and declarations preceding the unit. */
5033 /* Process the unit itself. */
5036 /* Generate code for all the inlined subprograms. */
5040 {
5041 Node_Id gnat_body;
5043 /* Without optimization, process only the required subprograms. */
5049 {
5050 /* ??? This happens when only the spec of a package is provided. */
5054 gnat_body
5056 }
5058 /* Define the entity first so we set DECL_EXTERNAL. */
5061 }
5063 /* Process any pragmas and actions following the unit. */
5068 /* Save away what we've made so far and record this potential elaboration
5069 procedure. */
5082 /* Generate elaboration code for this unit, if necessary, and say whether
5083 we did or not. */
5086 /* Invalidate the global renaming pointers. This is necessary because
5087 stabilization of the renamed entities may create SAVE_EXPRs which
5088 have been tied to a specific elaboration routine just above. */
5091 /* Force the processing for all nodes that remain in the queue. */
5093 }
5094 \f
5095 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5096 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5097 we should place the result type. LABEL_P is true if there is a label to
5098 branch to for the exception. */
5100 static tree
5102 {
5106 const bool with_extra_info
5107 = Exception_Extra_Info
5115 {
5125 {
5131 {
5151 }
5158 && gnu_low_bound
5159 && gnu_high_bound
5162 gnu_result
5166 /* If loop unswitching is enabled, we try to compute invariant
5167 conditions for checks applied to iteration variables, i.e.
5168 conditions that are both independent of the variable and
5169 necessary in order for the check to fail in the course of
5170 some iteration, and prepend them to the original condition
5171 of the checks. This will make it possible later for the
5172 loop unswitching pass to replace the loop with two loops,
5173 one of which has the checks eliminated and the other has
5174 the original checks reinstated, and a run time selection.
5175 The former loop will be suitable for vectorization. */
5178 && (!gnu_low_bound
5180 && (!gnu_high_bound
5183 {
5188 boolean_true_node);
5190 boolean_type_node,
5193 }
5194 }
5199 }
5201 common:
5206 /* If the type is VOID, this is a statement, so we need to generate the code
5207 for the call. Handle a condition, if there is one. */
5209 {
5211 {
5216 }
5217 }
5218 else
5222 }
5223 \f
5224 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5225 parameter of a call. */
5227 static bool
5229 {
5244 }
5246 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5247 of an assignment or an actual parameter of a call. */
5249 static bool
5251 {
5252 Node_Kind kind;
5264 }
5266 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5267 as gigi is concerned. This is used to avoid conversions on the LHS. */
5269 static bool
5271 {
5274 /* The conversion must be on the LHS of an assignment or an actual parameter
5275 of a call. Otherwise, even if the conversion was essentially a no-op, it
5276 could de facto ensure type consistency and this should be preserved. */
5282 /* We're interested in artificial conversions generated by the front-end
5283 to make private types explicit, e.g. in Expand_Assign_Array. */
5290 /* The direct conversion to the underlying type is a no-op. */
5294 /* For an array subtype, the conversion to the PAIT is a no-op. */
5299 /* For a record subtype, the conversion to the type is a no-op. */
5305 }
5307 /* This function is the driver of the GNAT to GCC tree transformation process.
5308 It is the entry point of the tree transformer. GNAT_NODE is the root of
5309 some GNAT tree. Return the root of the corresponding GCC tree. If this
5310 is an expression, return the GCC equivalent of the expression. If this
5311 is a statement, return the statement or add it to the current statement
5312 group, in which case anything returned is to be interpreted as occurring
5313 after anything added. */
5315 tree
5317 {
5323 Node_Id gnat_temp;
5325 /* Save node number for error message and set location information. */
5329 /* If this node is a statement and we are only annotating types, return an
5330 empty statement list. */
5334 /* If this node is a non-static subexpression and we are only annotating
5335 types, make this into a NULL_EXPR. */
5342 N_Raise_Constraint_Error));
5351 {
5354 /* If this is a statement and we are at top level, it must be part of
5355 the elaboration procedure, so mark us as being in that procedure. */
5357 {
5360 }
5362 /* If we are in the elaboration procedure, check if we are violating a
5363 No_Elaboration_Code restriction by having a statement there. Don't
5364 check for a possible No_Elaboration_Code restriction violation on
5365 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5366 every nested real statement instead. This also avoids triggering
5367 spurious errors on dummy (empty) sequences created by the front-end
5368 for package bodies in some cases. */
5372 }
5375 {
5376 /********************************/
5377 /* Chapter 2: Lexical Elements */
5378 /********************************/
5386 /* If this is an atomic access on the RHS for which synchronization is
5387 required, build the atomic load. */
5394 {
5395 tree gnu_type;
5397 /* Get the type of the result, looking inside any padding and
5398 justified modular types. Then get the value in that type. */
5407 /* If the result overflows (meaning it doesn't fit in its base type),
5408 abort. We would like to check that the value is within the range
5409 of the subtype, but that causes problems with subtypes whose usage
5410 will raise Constraint_Error and with biased representation, so
5411 we don't. */
5413 }
5417 /* If a Entity is present, it means that this was one of the
5418 literals in a user-defined character type. In that case,
5419 just return the value in the CONST_DECL. Otherwise, use the
5420 character code. In that case, the base type should be an
5421 INTEGER_TYPE, but we won't bother checking for that. */
5425 else
5426 gnu_result
5427 = build_int_cst_type
5434 /* If this is of a fixed-point type, the value we want is the value of
5435 the corresponding integer. */
5437 {
5439 gnu_result_type);
5441 }
5443 else
5444 {
5447 /* First convert the value to a machine number if it isn't already.
5448 That will force the base to 2 for non-zero values and simplify
5449 the rest of the logic. */
5451 ur_realval
5457 else
5458 {
5459 REAL_VALUE_TYPE tmp;
5463 /* The base must be 2 as Machine guarantees this, so we scale
5464 the value, which we know can fit in the mantissa of the type
5465 (hence the use of that type above). */
5470 }
5472 /* Now see if we need to negate the result. Do it this way to
5473 properly handle -0. */
5475 gnu_result
5477 gnu_result);
5478 }
5485 {
5492 else
5495 /* Build the string with the characters in the literal. Note
5496 that Ada strings are 1-origin. */
5500 /* Put a null at the end of the string in case it's in a context
5501 where GCC will want to treat it as a C string. */
5506 /* Strings in GCC don't normally have types, but we want
5507 this to not be converted to the array type. */
5512 }
5513 else
5514 {
5515 /* Build a list consisting of each character, then make
5516 the aggregate. */
5526 {
5532 }
5535 }
5542 /**************************************/
5543 /* Chapter 3: Declarations and Types */
5544 /**************************************/
5561 /* If we are just annotating types and this object has an unconstrained
5562 or task type, don't elaborate it. */
5572 && (!type_annotate_only
5574 {
5577 gnu_expr
5580 /* If this object has its elaboration delayed, we must force
5581 evaluation of GNU_EXPR right now and save it for when the object
5582 is frozen. */
5584 {
5586 ;
5588 gnu_expr
5593 else
5597 }
5598 }
5599 else
5605 /* If this is a deferred constant with an address clause, we ignore the
5606 full view since the clause is on the partial view and we cannot have
5607 2 different GCC trees for the object. The only bits of the full view
5608 we will use is the initializer, but it will be directly fetched. */
5621 /* Don't do anything if this renaming is handled by the front end or if
5622 we are just annotating types and this object has a composite or task
5623 type, don't elaborate it. We return the result in case it has any
5624 SAVE_EXPRs in it that need to be evaluated here. */
5626 && ! (type_annotate_only
5630 gnu_result
5633 else
5640 gnu_result
5643 else
5655 /* These are fully handled in the front end. */
5656 /* ??? For package renamings, find a way to use GENERIC namespaces so
5657 that we get proper debug information for them. */
5661 /*************************************/
5662 /* Chapter 4: Names and Expressions */
5663 /*************************************/
5670 /* If this is an atomic access on the RHS for which synchronization is
5671 required, build the atomic load. */
5678 {
5680 tree gnu_type;
5687 /* Convert vector inputs to their representative array type, to fit
5688 what the code below expects. */
5690 {
5694 }
5698 /* If we got a padded type, remove it too. */
5700 gnu_array_object
5702 gnu_array_object);
5706 /* The failure of this assertion will very likely come from a missing
5707 expansion for a packed array access. */
5710 /* First compute the number of dimensions of the array, then
5711 fill the expression array, the order depending on whether
5712 this is a Convention_Fortran array or not. */
5717 ;
5726 else
5734 {
5740 gnu_expr
5741 = emit_index_check
5745 gnat_temp);
5747 gnu_result
5750 /* Array accesses are bound-checked so they cannot trap, but this
5751 is valid only if they are not hoisted ahead of the check. We
5752 need to mark them as no-trap to get decent loop optimizations
5753 in the presence of -fnon-call-exceptions, so we do it when we
5754 know that the original expression had no side-effects. */
5759 }
5763 /* If this is an atomic access on the RHS for which synchronization is
5764 required, build the atomic load. */
5768 }
5772 {
5774 tree gnu_type;
5779 /* Do any implicit dereferences of the prefix and do any needed
5780 range check. */
5785 {
5786 /* Get the bounds of the slice. */
5787 tree gnu_index_type
5791 /* Get the permitted bounds. */
5792 tree gnu_base_index_type
5794 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5796 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5803 /* Derive a good type to convert everything to. */
5806 /* Test whether the minimum slice value is too small. */
5809 gnu_min_expr),
5811 gnu_base_min_expr));
5813 /* Test whether the maximum slice value is too large. */
5816 gnu_max_expr),
5818 gnu_base_max_expr));
5820 /* Build a slice index check that returns the low bound,
5821 assuming the slice is not empty. */
5822 gnu_expr = emit_check
5827 /* Build a conditional expression that does the index checks and
5828 returns the low bound if the slice is not empty (max >= min),
5829 and returns the naked low bound otherwise (max < min), unless
5830 it is non-constant and the high bound is; this prevents VRP
5831 from inferring bogus ranges on the unlikely path. */
5835 gnu_max_expr),
5837 gnu_min_expr)),
5838 gnu_expr,
5842 }
5843 else
5844 /* Simply return the naked low bound. */
5847 /* If this is a slice with non-constant size of an array with constant
5848 size, set the maximum size for the allocation of temporaries. */
5855 }
5859 {
5863 tree gnu_field;
5867 /* For discriminant references in tagged types always substitute the
5868 corresponding discriminant as the actual selected component. */
5873 /* For discriminant references of untagged types always substitute the
5874 corresponding stored discriminant. */
5878 /* Handle extracting the real or imaginary part of a complex.
5879 The real part is the first field and the imaginary the last. */
5884 else
5885 {
5888 /* If there are discriminants, the prefix might be evaluated more
5889 than once, which is a problem if it has side-effects. */
5896 gnu_result
5900 && lvalue_required_for_attribute_p
5902 }
5906 /* If this is an atomic access on the RHS for which synchronization is
5907 required, build the atomic load. */
5911 }
5915 {
5916 /* The attribute designator. */
5919 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
5920 is a unit, not an object with a GCC equivalent. */
5922 return
5930 }
5934 /* Like 'Access as far as we are concerned. */
5942 {
5943 tree gnu_aggr_type;
5945 /* ??? It is wrong to evaluate the type now, but there doesn't
5946 seem to be any other practical way of doing it. */
5950 gnu_aggr_type = gnu_result_type
5955 gnu_aggr_type
5962 NULL);
5966 gnu_result
5969 gnu_aggr_type);
5972 gnu_aggr_type,
5975 gnu_result
5976 = build_binary_op
5981 (Next
5983 else
5987 }
5995 else
6002 /* Get the operand expression. */
6006 /* If this is a qualified expression for a tagged type, we mark the type
6007 as used. Because of polymorphism, this might be the only reference to
6008 the tagged type in the program while objects have it as dynamic type.
6009 The debugger needs to see it to display these objects properly. */
6013 gnu_result
6017 kind == N_Type_Conversion
6024 /* Skip further processing if the conversion is deemed a no-op. */
6026 {
6029 }
6033 /* If the result is a pointer type, see if we are improperly
6034 converting to a stricter alignment. */
6037 {
6043 post_error_ne_tree_2
6047 }
6049 /* If we are converting a descriptor to a function pointer, first
6050 build the pointer. */
6062 {
6067 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6068 subtype. */
6070 {
6073 }
6076 {
6080 gnu_low
6082 gnu_high
6084 }
6085 else
6090 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6091 ensure that GNU_OBJ is evaluated only once and perform a full range
6092 test. */
6094 gnu_result
6096 else
6097 {
6106 gnu_result
6108 }
6111 gnu_result
6113 }
6121 ? RDIV_EXPR
6128 /* These can either be operations on booleans or on modular types.
6129 Fall through for boolean types since that's the way GNU_CODES is
6130 set up. */
6132 {
6133 enum tree_code code
6144 }
6146 /* ... fall through ... */
6158 {
6162 tree gnu_type;
6168 /* Pending generic support for efficient vector logical operations in
6169 GCC, convert vectors to their representative array type view and
6170 fallthrough. */
6174 /* If this is a comparison operator, convert any references to an
6175 unconstrained array value into a reference to the actual array. */
6177 {
6180 }
6182 /* If this is a shift whose count is not guaranteed to be correct,
6183 we need to adjust the shift count. */
6185 {
6187 tree gnu_max_shift
6194 gnu_rhs
6195 = build_binary_op
6198 gnu_count_type,
6199 gnu_max_shift,
6201 integer_one_node)),
6202 gnu_rhs);
6203 }
6205 /* For right shifts, the type says what kind of shift to do,
6206 so we may need to choose a different type. In this case,
6207 we have to ignore integer overflow lest it propagates all
6208 the way down and causes a CE to be explicitly raised. */
6210 {
6213 }
6216 {
6219 }
6222 {
6228 }
6230 /* Instead of expanding overflow checks for addition, subtraction
6231 and multiplication itself, the front end will leave this to
6232 the back end when Backend_Overflow_Checks_On_Target is set.
6233 As the GCC back end itself does not know yet how to properly
6234 do overflow checking, do it here. The goal is to push
6235 the expansions further into the back end over time. */
6244 else
6245 {
6246 /* Some operations, e.g. comparisons of arrays, generate complex
6247 trees that need to be annotated while they are being built. */
6250 }
6252 /* If this is a logical shift with the shift count not verified,
6253 we must return zero if it is too large. We cannot compensate
6254 above in this case. */
6257 gnu_result
6258 = build_cond_expr
6261 gnu_rhs,
6265 gnu_result);
6266 }
6270 {
6273 tree gnu_false
6277 gnu_result
6279 }
6288 /* This case can apply to a boolean or a modular type.
6289 Fall through for a boolean operand since GNU_CODES is set
6290 up to handle this. */
6292 {
6296 gnu_expr);
6298 }
6300 /* ... fall through ... */
6309 gnu_result
6312 else
6318 {
6320 tree gnu_type;
6325 /* The Expression operand can either be an N_Identifier or
6326 Expanded_Name, which must represent a type, or a
6327 N_Qualified_Expression, which contains both the object type and an
6328 initial value for the object. */
6333 {
6334 Entity_Id gnat_desig_type
6342 gnu_init
6348 else
6349 {
6353 }
6355 /* See the N_Qualified_Expression case for the rationale. */
6360 }
6361 else
6368 ignore_init_type);
6369 }
6372 /**************************/
6373 /* Chapter 5: Statements */
6374 /**************************/
6382 /* When not optimizing, turn null statements from source into gotos to
6383 the next statement that the middle-end knows how to preserve. */
6385 {
6396 }
6397 else
6402 /* Get the LHS and RHS of the statement and convert any reference to an
6403 unconstrained array into a reference to the underlying array. */
6406 /* If the type has a size that overflows, convert this into raise of
6407 Storage_Error: execution shouldn't have gotten here anyway. */
6411 N_Raise_Storage_Error);
6413 gnu_result
6416 else
6417 {
6419 const Entity_Id gnat_type
6421 const bool regular_array_type_p
6423 const bool use_memset_p
6424 = (regular_array_type_p
6428 /* If we'll use memset, we need to find the inner expression. */
6430 {
6431 Node_Id gnat_inner
6435 gnat_inner
6438 }
6439 else
6442 /* If range check is needed, emit code to generate it. */
6445 gnat_node);
6447 /* If atomic synchronization is required, build an atomic store. */
6451 /* Or else, use memset when the conditions are met. */
6453 {
6457 tree size
6462 {
6463 tree mask
6467 }
6469 }
6471 /* Otherwise build a regular assignment. */
6472 else
6473 gnu_result
6476 /* If the assignment type is a regular array and the two sides are
6477 not completely disjoint, play safe and use memmove. But don't do
6478 it for a bit-packed array as it might not be byte-aligned. */
6480 && regular_array_type_p
6482 {
6486 tree size
6492 }
6493 }
6497 {
6500 /* Make the outer COND_EXPR. Avoid non-determinism. */
6509 /* Now make a COND_EXPR for each of the "else if" parts. Put each
6510 into the previous "else" part and point to where to put any
6511 outer "else". Also avoid non-determinism. */
6515 {
6525 }
6528 }
6540 /* The only way to enter the block is to fall through to it. */
6542 {
6549 }
6550 else
6555 gnu_result
6565 {
6568 /* If the subprogram is a function, we must return the expression. */
6570 {
6573 /* If this function has copy-in/copy-out parameters parameters and
6574 doesn't return by invisible reference, get the real object for
6575 the return. See Subprogram_Body_to_gnu. */
6579 else
6582 /* Get the GCC tree for the expression to be returned. */
6585 /* Do not remove the padding from GNU_RET_VAL if the inner type is
6586 self-referential since we want to allocate the fixed size. */
6588 && TYPE_IS_PADDING_P
6590 && CONTAINS_PLACEHOLDER_P
6594 /* If the function returns by direct reference, return a pointer
6595 to the return value. */
6600 /* Otherwise, if it returns an unconstrained array, we have to
6601 allocate a new version of the result and return it. */
6603 {
6606 /* And find out whether this is a candidate for Named Return
6607 Value. If so, record it. */
6609 {
6612 /* Strip useless conversions around the return value. */
6616 /* Strip unpadding around the return value. */
6618 && TYPE_IS_PADDING_P
6622 /* Now apply the test to the return value. */
6624 {
6630 }
6631 }
6634 gnu_ret_val,
6639 }
6641 /* Otherwise, if it returns by invisible reference, dereference
6642 the pointer it is passed using the type of the return value
6643 and build the copy operation manually. This ensures that we
6644 don't copy too much data, for example if the return type is
6645 unconstrained with a maximum size. */
6647 {
6648 tree gnu_ret_deref
6650 gnu_ret_obj);
6655 }
6656 }
6658 else
6661 /* If we have a return label defined, convert this into a branch to
6662 that label. The return proper will be handled elsewhere. */
6664 {
6667 gnu_ret_val));
6672 /* When not optimizing, make sure the return is preserved. */
6675 }
6677 /* Otherwise, build a regular return. */
6678 else
6680 }
6684 gnu_result
6688 /***************************/
6689 /* Chapter 6: Subprograms */
6690 /***************************/
6693 /* Unless there is a freeze node, declare the subprogram. We consider
6694 this a "definition" even though we're not generating code for
6695 the subprogram because we will be making the corresponding GCC
6696 node here. */
6705 /* This subprogram doesn't exist for code generation purposes, but we
6706 have to elaborate the types of any parameters and result, unless
6707 they are imported types (nothing to generate in this case).
6709 The parameter list may contain types with freeze nodes, e.g. not null
6710 subtypes, so the subprogram itself may carry a freeze node, in which
6711 case its elaboration must be deferred. */
6713 /* Process the parameter types first. */
6716 = First_Formal_With_Extras
6724 /* Then the result type, set to Standard_Void_Type for procedures. */
6725 {
6726 Entity_Id gnat_temp_type
6731 }
6737 /* For a child unit identifier go up a level to get the specification.
6738 We get this when we try to find the spec of a child unit package
6739 that is the compilation unit being compiled. */
6753 /************************/
6754 /* Chapter 7: Packages */
6755 /************************/
6771 /* If this is the body of a generic package - do nothing. */
6773 {
6776 }
6787 /********************************/
6788 /* Chapter 8: Visibility Rules */
6789 /********************************/
6793 /* Nothing to do here - but these may appear in list of declarations. */
6797 /*********************/
6798 /* Chapter 9: Tasks */
6799 /*********************/
6810 /*********************************************************/
6811 /* Chapter 10: Program Structure and Compilation Issues */
6812 /*********************************************************/
6815 /* This is not called for the main unit on which gigi is invoked. */
6824 /* Simply process whatever unit is being inserted. */
6827 else
6828 {
6831 }
6838 /***************************/
6839 /* Chapter 11: Exceptions */
6840 /***************************/
6843 /* If there is an At_End procedure attached to this node, and the EH
6844 mechanism is SJLJ, we must have at least a corresponding At_End
6845 handler, unless the No_Exception_Handlers restriction is set. */
6860 else
6865 /* Only for reraise in back-end exceptions mode. */
6872 /* Clear the current exception pointer so that the occurrence won't be
6873 deallocated. */
6912 /******************************/
6913 /* Chapter 12: Generic Units */
6914 /******************************/
6924 /* These nodes can appear on a declaration list but there is nothing to
6925 to be done with them. */
6929 /**************************************************/
6930 /* Chapter 13: Representation Clauses and */
6931 /* Implementation-Dependent Features */
6932 /**************************************************/
6937 /* The only one we need to deal with is 'Address since, for the others,
6938 the front-end puts the information elsewhere. */
6942 /* And we only deal with 'Address if the object has a Freeze node. */
6947 /* Get the value to use as the address and save it as the equivalent
6948 for the object. When it is frozen, gnat_to_gnu_entity will do the
6949 right thing. */
6956 /* We do nothing with these. SEM puts the information elsewhere. */
6962 {
6972 /* First retrieve the 3 operand lists built by the front-end. */
6975 {
6982 }
6986 {
6993 }
6997 gnu_clobbers
7000 gnu_clobbers);
7002 /* Then perform some standard checking and processing on the
7003 operands. In particular, mark them addressable if needed. */
7011 {
7013 constraint
7019 {
7020 /* If the operand is going to end up in memory,
7021 mark it addressable. Note that we don't test
7022 allows_mem like in the input case below; this
7023 is modelled on the C front-end. */
7025 {
7032 }
7033 }
7034 else
7038 }
7041 {
7043 constraint
7049 {
7050 /* If the operand is going to end up in memory,
7051 mark it addressable. */
7053 {
7060 }
7061 }
7062 else
7066 }
7072 }
7073 else
7078 /****************/
7079 /* Added Nodes */
7080 /****************/
7083 /* This construct doesn't define a scope so we don't push a binding level
7084 around the statement list; but we wrap it in a SAVE_EXPR to protect it
7085 from unsharing. */
7090 gnu_result
7115 {
7120 /* If this is a thin pointer, we must first dereference it to create
7121 a fat pointer, then go back below to a thin pointer. The reason
7122 for this is that we need to have a fat pointer someplace in order
7123 to properly compute the size. */
7127 gnu_ptr));
7129 /* If this is a fat pointer, the object must have been allocated with
7130 the template in front of the array. So pass the template address,
7131 and get the total size; do it by converting to a thin pointer. */
7133 gnu_ptr
7135 (TYPE_OBJECT_RECORD_TYPE
7137 gnu_ptr);
7141 /* If this is a thin pointer, the object must have been allocated with
7142 the template in front of the array. So pass the template address,
7143 and get the total size. */
7145 gnu_ptr
7147 gnu_ptr,
7149 byte_position
7150 (DECL_CHAIN
7153 /* If we have a special dynamic constrained subtype on the node, use
7154 it to compute the size; otherwise, use the designated subtype. */
7156 {
7157 gnu_actual_obj_type
7161 gnu_actual_obj_type
7163 gnu_actual_obj_type,
7166 }
7167 else
7170 gnu_result
7173 gnu_obj_type,
7176 gnat_node);
7177 }
7185 else
7190 /* The only validation we currently do on an unchecked conversion is
7191 that of aliasing assumptions. */
7203 /* These nodes should only be present when annotating types. */
7209 /* Other nodes are not supposed to reach here. */
7211 }
7213 /* If we pushed the processing of the elaboration routine, pop it back. */
7217 /* When not optimizing, turn boolean rvalues B into B != false tests
7218 so that the code just below can put the location information of the
7219 reference to B on the inequality operator for better debug info. */
7233 boolean_false_node));
7235 /* Set the location information on the result. Note that we may have
7236 no result if we tried to build a CALL_EXPR node to a procedure with
7237 no side-effects and optimization is enabled. */
7241 /* If we're supposed to return something of void_type, it means we have
7242 something we're elaborating for effect, so just return. */
7246 /* If the result is a constant that overflowed, raise Constraint_Error. */
7248 {
7250 gnu_result
7253 N_Raise_Constraint_Error));
7254 }
7256 /* If the result has side-effects and is of an unconstrained type, make a
7257 SAVE_EXPR so that we can be sure it will only be referenced once. But
7258 this is useless for a call to a function that returns an unconstrained
7259 type with default discriminant, as we cannot compute the size of the
7260 actual returned object. We must do this before any conversions. */
7268 /* Now convert the result to the result type, unless we are in one of the
7269 following cases:
7271 1. If this is the LHS of an assignment or an actual parameter of a
7272 call, return the result almost unmodified since the RHS will have
7273 to be converted to our type in that case, unless the result type
7274 has a simpler size. Likewise if there is just a no-op unchecked
7275 conversion in-between. Similarly, don't convert integral types
7276 that are the operands of an unchecked conversion since we need
7277 to ignore those conversions (for 'Valid).
7279 2. If we have a label (which doesn't have any well-defined type), a
7280 field or an error, return the result almost unmodified. Similarly,
7281 if the two types are record types with the same name, don't convert.
7282 This will be the case when we are converting from a packable version
7283 of a type to its original type and we need those conversions to be
7284 NOPs in order for assignments into these types to work properly.
7286 3. If the type is void or if we have no result, return error_mark_node
7287 to show we have no result.
7289 4. If this a call to a function that returns an unconstrained type with
7290 default discriminant, return the call expression unmodified since we
7291 cannot compute the size of the actual returned object.
7293 5. Finally, if the type of the result is already correct. */
7311 && (CONTAINS_PLACEHOLDER_P
7315 {
7316 /* Remove padding only if the inner object is of self-referential
7317 size: in that case it must be an object of unconstrained type
7318 with a default discriminant and we want to avoid copying too
7319 much data. */
7324 gnu_result);
7325 }
7334 {
7335 /* Remove any padding. */
7338 gnu_result);
7339 }
7347 == gnu_result_type
7349 ;
7354 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7361 }
7362 \f
7363 /* Subroutine of above to push the exception label stack. GNU_STACK is
7364 a pointer to the stack to update and GNAT_LABEL, if present, is the
7365 label to push onto the stack. */
7367 static void
7369 {
7375 }
7376 \f
7377 /* Record the current code position in GNAT_NODE. */
7379 static void
7381 {
7386 }
7388 /* Insert the code for GNAT_NODE at the position saved for that node. */
7390 static void
7392 {
7395 }
7396 \f
7397 /* Start a new statement group chained to the previous group. */
7399 void
7401 {
7404 /* First see if we can get one from the free list. */
7407 else
7413 }
7415 /* Add GNU_STMT to the current statement group. If it is an expression with
7416 no effects, it is ignored. */
7418 void
7420 {
7422 }
7424 /* Similar, but the statement is always added, regardless of side-effects. */
7426 void
7428 {
7430 }
7432 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7434 void
7436 {
7437 /* Do not emit a location for renamings that come from generic instantiation,
7438 they are likely to disturb debugging. */
7443 }
7445 /* Similar, but the statement is always added, regardless of side-effects. */
7447 void
7449 {
7453 }
7455 /* Add a declaration statement for GNU_DECL to the current statement group.
7456 Get SLOC from Entity_Id. */
7458 void
7460 {
7464 /* If this is a variable that Gigi is to ignore, we may have been given
7465 an ERROR_MARK. So test for it. We also might have been given a
7466 reference for a renaming. So only do something for a decl. Also
7467 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7475 /* If we are external or global, we don't want to output the DECL_EXPR for
7476 this DECL node since we already have evaluated the expressions in the
7477 sizes and positions as globals and doing it again would be wrong. */
7479 {
7480 /* Mark everything as used to prevent node sharing with subprograms.
7481 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7482 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7486 {
7490 }
7491 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
7496 }
7497 else
7500 /* If this is a variable and an initializer is attached to it, it must be
7501 valid for the context. Similar to init_const in create_var_decl_1. */
7508 {
7509 /* If GNU_DECL has a padded type, convert it to the unpadded
7510 type so the assignment is done properly. */
7513 else
7520 {
7523 }
7526 }
7527 }
7529 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
7531 static tree
7533 {
7539 /* Don't mark a dummy type as visited because we want to mark its sizes
7540 and fields once it's filled in. */
7548 }
7550 /* Mark nodes rooted at T with TREE_VISITED and types as having their
7551 sized gimplified. We use this to indicate all variable sizes and
7552 positions in global types may not be shared by any subprogram. */
7554 void
7556 {
7558 }
7560 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
7561 set its location to that of GNAT_NODE if present, but with column info
7562 cleared so that conditional branches generated as part of the cleanup
7563 code do not interfere with coverage analysis tools. */
7565 static void
7567 {
7571 }
7573 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
7575 void
7577 {
7580 }
7582 /* Return code corresponding to the current code group. It is normally
7583 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
7584 BLOCK or cleanups were set. */
7586 tree
7588 {
7592 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
7593 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
7594 make a BIND_EXPR. Note that we nest in that because the cleanup may
7595 reference variables in the block. */
7607 /* Remove this group from the stack and add it to the free list. */
7613 }
7615 /* Return whether the current statement group may fall through. */
7619 {
7622 else
7624 }
7626 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
7627 statements.*/
7629 static void
7631 {
7632 Node_Id gnat_node;
7638 }
7640 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
7641 If BINDING_P is true, push and pop a binding level around the list. */
7643 static tree
7645 {
7655 }
7656 \f
7657 /* Generate GIMPLE in place for the expression at *EXPR_P. */
7659 int
7662 {
7665 tree op;
7671 {
7673 /* If this is an aggregate type, build a null pointer of the appropriate
7674 type and dereference it. */
7679 integer_zero_node));
7680 /* Otherwise, just make a VAR_DECL. */
7681 else
7682 {
7685 }
7691 /* We should only do this if we are just elaborating for side-effects,
7692 but we can't know that yet. */
7699 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
7700 is put into static memory. We know that it's going to be read-only
7701 given the semantics we have and it must be in static memory when the
7702 reference is in an elaboration procedure. */
7704 {
7708 }
7715 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
7716 type to a scalar one, explicitly create the local temporary. That's
7717 required if the type is passed by reference. */
7721 {
7730 }
7737 /* The expressions for the RM bounds must be gimplified to ensure that
7738 they are properly elaborated. See gimplify_decl_expr. */
7742 {
7747 {
7752 {
7756 }
7760 {
7764 }
7766 }
7771 }
7773 /* ... fall through ... */
7777 }
7778 }
7780 /* Generate GIMPLE in place for the statement at *STMT_P. */
7782 static enum gimplify_status
7784 {
7788 {
7794 {
7800 /* Build the condition expression from the test, if any. */
7802 {
7803 /* Deal with the optimization hints. */
7807 annot_expr_ivdep_kind));
7811 annot_expr_no_vector_kind));
7815 annot_expr_vector_kind));
7817 gnu_cond
7820 }
7822 /* Set to emit the statements of the loop. */
7825 /* We first emit the start label and then a conditional jump to the
7826 end label if there's a top condition, then the update if it's at
7827 the top, then the body of the loop, then a conditional jump to
7828 the end label if there's a bottom condition, then the update if
7829 it's at the bottom, and finally a jump to the start label and the
7830 definition of the end label. */
7832 gnu_start_label),
7833 stmt_p);
7854 gnu_end_label),
7855 stmt_p);
7857 }
7860 /* Build a statement to jump to the corresponding end label, then
7861 see if it needs to be conditional. */
7870 }
7871 }
7872 \f
7873 /* Force references to each of the entities in packages withed by GNAT_NODE.
7874 Operate recursively but check that we aren't elaborating something more
7875 than once.
7877 This routine is exclusively called in type_annotate mode, to compute DDA
7878 information for types in withed units, for ASIS use. */
7880 static void
7882 {
7885 /* Process each unit only once. As we trace the context of all relevant
7886 units transitively, including generic bodies, we may encounter the
7887 same generic unit repeatedly. */
7891 /* Save entities in all context units. A body may have an implicit_with
7892 on its own spec, if the context includes a child unit, so don't save
7893 the spec twice. */
7900 {
7904 {
7921 }
7923 {
7924 Node_Id gnat_body
7927 /* Retrieve compilation unit node of generic body. */
7932 /* If body is available, elaborate its context. */
7935 }
7936 }
7940 }
7941 \f
7942 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
7944 static void
7946 {
7951 /* If this is a package, we need to generate code for the package. */
7953 {
7954 insert_code_for
7958 }
7960 /* Don't do anything for class-wide types as they are always transformed
7961 into their root type. */
7965 /* Check for an old definition. This freeze node might be for an Itype. */
7966 gnu_old
7969 /* If this entity has an address representation clause, GNU_OLD is the
7970 address, so discard it here. */
7974 /* Don't do anything for subprograms that may have been elaborated before
7975 their freeze nodes. This can happen, for example, because of an inner
7976 call in an instance body or because of previous compilation of a spec
7977 for inlining purposes. */
7985 /* If we have a non-dummy type old tree, we have nothing to do, except
7986 aborting if this is the public view of a private type whose full view was
7987 not delayed, as this node was never delayed as it should have been. We
7988 let this happen for concurrent types and their Corresponding_Record_Type,
7989 however, because each might legitimately be elaborated before its own
7990 freeze node, e.g. while processing the other. */
7994 {
8002 }
8004 /* Reset the saved tree, if any, and elaborate the object or type for real.
8005 If there is a full view, elaborate it and use the result. And, if this
8006 is the root type of a class-wide type, reuse it for the latter. */
8008 {
8013 {
8020 {
8023 }
8024 }
8030 }
8034 {
8043 /* Propagate back-annotations from full view to partial view. */
8053 /* The above call may have defined this entity (the simplest example
8054 of this is when we have a private enumeral type since the bounds
8055 will have the public view). */
8058 }
8059 else
8060 {
8061 tree gnu_init
8067 }
8074 /* If we have an old type and we've made pointers to this type, update those
8075 pointers. If this is a Taft amendment type in the main unit, we need to
8076 mark the type as used since other units referencing it don't see the full
8077 declaration and, therefore, cannot mark it as used themselves. */
8079 {
8084 }
8085 }
8086 \f
8087 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8088 We make two passes, one to elaborate anything other than bodies (but
8089 we declare a function if there was no spec). The second pass
8090 elaborates the bodies.
8092 GNAT_END_LIST gives the element in the list past the end. Normally,
8093 this is Empty, but can be First_Real_Statement for a
8094 Handled_Sequence_Of_Statements.
8096 We make a complete pass through both lists if PASS1P is true, then make
8097 the second pass over both lists if PASS2P is true. The lists usually
8098 correspond to the public and private parts of a package. */
8100 static void
8103 {
8105 Node_Id gnat_decl;
8115 {
8116 /* For package specs, we recurse inside the declarations,
8117 thus taking the two pass approach inside the boundary. */
8125 /* Similarly for any declarations in the actions of a
8126 freeze node. */
8128 {
8131 }
8133 /* Package bodies with freeze nodes get their elaboration deferred
8134 until the freeze node, but the code must be placed in the right
8135 place, so record the code position now. */
8143 (Corresponding_Spec
8146 record_code_position
8149 /* We defer most subprogram bodies to the second pass. */
8151 {
8153 {
8159 }
8160 }
8162 /* For bodies and stubs that act as their own specs, the entity
8163 itself must be elaborated in the first pass, because it may
8164 be used in other declarations. */
8166 {
8167 Node_Id gnat_subprog_id
8174 }
8176 /* Concurrent stubs stand for the corresponding subprogram bodies,
8177 which are deferred like other bodies. */
8180 ;
8182 else
8184 }
8186 /* Here we elaborate everything we deferred above except for package bodies,
8187 which are elaborated at their freeze nodes. Note that we must also
8188 go inside things (package specs and freeze nodes) the first pass did. */
8194 {
8210 }
8211 }
8212 \f
8213 /* Make a unary operation of kind CODE using build_unary_op, but guard
8214 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8215 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8216 the operation is to be performed in that type. GNAT_NODE is the gnat
8217 node conveying the source location for which the error should be
8218 signaled. */
8220 static tree
8222 Node_Id gnat_node)
8223 {
8232 }
8234 /* Make a binary operation of kind CODE using build_binary_op, but guard
8235 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8236 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8237 Usually the operation is to be performed in that type. GNAT_NODE is
8238 the GNAT node conveying the source location for which the error should
8239 be signaled. */
8241 static tree
8244 {
8254 /* Assert that the precision is a power of 2. */
8257 /* Prefer a constant or known-positive rhs to simplify checks. */
8263 {
8267 }
8271 /* If we can fold the expression to a constant, just return it.
8272 The caller will deal with overflow, no need to generate a check. */
8277 ? boolean_false_node
8280 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8282 /* Try a few strategies that may be cheaper than the general
8283 code at the end of the function, if the rhs is not known.
8284 The strategies are:
8285 - Call library function for 64-bit multiplication (complex)
8286 - Widen, if input arguments are sufficiently small
8287 - Determine overflow using wrapped result for addition/subtraction. */
8290 {
8291 /* Even for add/subtract double size to get another base type. */
8295 {
8301 }
8305 {
8311 check = build_binary_op
8318 return
8320 }
8323 {
8325 tree wrapped_expr
8331 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8332 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8333 check
8337 boolean_type_node,
8340 return
8342 }
8343 }
8346 {
8348 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8353 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8360 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8365 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8372 /* The check here is designed to be efficient if the rhs is constant,
8373 but it will work for any rhs by using integer division.
8374 Four different check expressions determine whether X * C overflows,
8375 depending on C.
8376 C == 0 => false
8377 C > 0 => X > type_max / C || X < type_min / C
8378 C == -1 => X == type_min
8379 C < -1 => X > type_min / C || X < type_max / C */
8384 check_pos
8387 rhs),
8390 boolean_type_node,
8393 boolean_type_node,
8396 check_neg
8401 type_min),
8404 boolean_type_node,
8407 boolean_type_node,
8413 }
8416 check_pos);
8419 }
8421 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
8422 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
8423 which we have to check. GNAT_NODE is the GNAT node conveying the source
8424 location for which the error should be signaled. */
8426 static tree
8428 {
8432 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
8433 This can for example happen when translating 'Val or 'Value. */
8437 /* Range checks can only be applied to types with ranges. */
8441 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
8442 we can't do anything since we might be truncating the bounds. No
8443 check is needed in this case. */
8449 /* Checked expressions must be evaluated only once. */
8452 /* Note that the form of the check is
8453 (not (expr >= lo)) or (not (expr <= hi))
8454 the reason for this slightly convoluted form is that NaNs
8455 are not considered to be in range in the float case. */
8456 return emit_check
8458 invert_truthvalue
8462 TYPE_MIN_VALUE
8464 invert_truthvalue
8468 TYPE_MAX_VALUE
8471 }
8472 \f
8473 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
8474 we are about to index, GNU_EXPR is the index expression to be checked,
8475 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
8476 has to be checked. Note that for index checking we cannot simply use the
8477 emit_range_check function (although very similar code needs to be generated
8478 in both cases) since for index checking the array type against which we are
8479 checking the indices may be unconstrained and consequently we need to get
8480 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
8481 The place where we need to do that is in subprograms having unconstrained
8482 array formal parameters. GNAT_NODE is the GNAT node conveying the source
8483 location for which the error should be signaled. */
8485 static tree
8488 {
8489 tree gnu_expr_check;
8491 /* Checked expressions must be evaluated only once. */
8494 /* Must do this computation in the base type in case the expression's
8495 type is an unsigned subtypes. */
8498 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
8499 the object we are handling. */
8503 return emit_check
8506 gnu_expr_check,
8508 gnu_low)),
8510 gnu_expr_check,
8512 gnu_high))),
8514 }
8515 \f
8516 /* GNU_COND contains the condition corresponding to an access, discriminant or
8517 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
8518 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
8519 REASON is the code that says why the exception was raised. GNAT_NODE is
8520 the GNAT node conveying the source location for which the error should be
8521 signaled. */
8523 static tree
8525 {
8526 tree gnu_call
8528 tree gnu_result
8532 gnu_expr);
8534 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
8535 we don't need to evaluate it just for the check. */
8539 }
8540 \f
8541 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
8542 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
8543 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
8544 float to integer conversion with truncation; otherwise round.
8545 GNAT_NODE is the GNAT node conveying the source location for which the
8546 error should be signaled. */
8548 static tree
8551 {
8558 /* If we are not doing any checks, the output is an integral type and the
8559 input is not a floating-point type, just do the conversion. This is
8560 required for packed array types and is simpler in all cases anyway. */
8562 && !overflowp
8567 /* First convert the expression to its base type. This
8568 will never generate code, but makes the tests below much simpler.
8569 But don't do this if converting from an integer type to an unconstrained
8570 array type since then we need to get the bounds from the original
8571 (unpacked) type. */
8575 /* If overflow checks are requested, we need to be sure the result will
8576 fit in the output base type. But don't do this if the input
8577 is integer and the output floating-point. */
8580 {
8581 /* Ensure GNU_EXPR only gets evaluated once. */
8589 /* Convert the lower bounds to signed types, so we're sure we're
8590 comparing them properly. Likewise, convert the upper bounds
8591 to unsigned types. */
8605 /* Check each bound separately and only if the result bound
8606 is tighter than the bound on the input type. Note that all the
8607 types are base types, so the bounds must be constant. Also,
8608 the comparison is done in the base type of the input, which
8609 always has the proper signedness. First check for input
8610 integer (which means output integer), output float (which means
8611 both float), or mixed, in which case we always compare.
8612 Note that we have to do the comparison which would *fail* in the
8613 case of an error since if it's an FP comparison and one of the
8614 values is a NaN or Inf, the comparison will fail. */
8621 gnu_cond
8622 = invert_truthvalue
8625 gnu_out_lb)));
8633 gnu_cond
8635 invert_truthvalue
8637 gnu_input,
8639 gnu_out_ub))));
8644 }
8646 /* Now convert to the result base type. If this is a non-truncating
8647 float-to-integer conversion, round. */
8651 {
8657 /* The following calculations depend on proper rounding to even
8658 of each arithmetic operation. In order to prevent excess
8659 precision from spoiling this property, use the widest hardware
8660 floating-point type if FP_ARITH_MAY_WIDEN is true. */
8661 calc_type
8664 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
8668 half_minus_pred_half);
8671 /* If the input is strictly negative, subtract this value
8672 and otherwise add it from the input. For 0.5, the result
8673 is exactly between 1.0 and the machine number preceding 1.0
8674 (for calc_type). Since the last bit of 1.0 is even, this 0.5
8675 will round to 1.0, while all other number with an absolute
8676 value less than 0.5 round to 0.0. For larger numbers exactly
8677 halfway between integers, rounding will always be correct as
8678 the true mathematical result will be closer to the higher
8679 integer compared to the lower one. So, this constant works
8680 for all floating-point numbers.
8682 The reason to use the same constant with subtract/add instead
8683 of a positive and negative constant is to allow the comparison
8684 to be scheduled in parallel with retrieval of the constant and
8685 conversion of the input to the calc_type (if necessary). */
8690 gnu_comp
8692 gnu_add_pred_half
8694 gnu_subtract_pred_half
8698 }
8704 else
8707 /* Finally, do the range check if requested. Note that if the result type
8708 is a modular type, the range check is actually an overflow check. */
8715 }
8716 \f
8717 /* Return true if GNU_EXPR can be directly addressed. This is the case
8718 unless it is an expression involving computation or if it involves a
8719 reference to a bitfield or to an object not sufficiently aligned for
8720 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
8721 be directly addressed as an object of this type.
8723 *** Notes on addressability issues in the Ada compiler ***
8725 This predicate is necessary in order to bridge the gap between Gigi
8726 and the middle-end about addressability of GENERIC trees. A tree
8727 is said to be addressable if it can be directly addressed, i.e. if
8728 its address can be taken, is a multiple of the type's alignment on
8729 strict-alignment architectures and returns the first storage unit
8730 assigned to the object represented by the tree.
8732 In the C family of languages, everything is in practice addressable
8733 at the language level, except for bit-fields. This means that these
8734 compilers will take the address of any tree that doesn't represent
8735 a bit-field reference and expect the result to be the first storage
8736 unit assigned to the object. Even in cases where this will result
8737 in unaligned accesses at run time, nothing is supposed to be done
8738 and the program is considered as erroneous instead (see PR c/18287).
8740 The implicit assumptions made in the middle-end are in keeping with
8741 the C viewpoint described above:
8742 - the address of a bit-field reference is supposed to be never
8743 taken; the compiler (generally) will stop on such a construct,
8744 - any other tree is addressable if it is formally addressable,
8745 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
8747 In Ada, the viewpoint is the opposite one: nothing is addressable
8748 at the language level unless explicitly declared so. This means
8749 that the compiler will both make sure that the trees representing
8750 references to addressable ("aliased" in Ada parlance) objects are
8751 addressable and make no real attempts at ensuring that the trees
8752 representing references to non-addressable objects are addressable.
8754 In the first case, Ada is effectively equivalent to C and handing
8755 down the direct result of applying ADDR_EXPR to these trees to the
8756 middle-end works flawlessly. In the second case, Ada cannot afford
8757 to consider the program as erroneous if the address of trees that
8758 are not addressable is requested for technical reasons, unlike C;
8759 as a consequence, the Ada compiler must arrange for either making
8760 sure that this address is not requested in the middle-end or for
8761 compensating by inserting temporaries if it is requested in Gigi.
8763 The first goal can be achieved because the middle-end should not
8764 request the address of non-addressable trees on its own; the only
8765 exception is for the invocation of low-level block operations like
8766 memcpy, for which the addressability requirements are lower since
8767 the type's alignment can be disregarded. In practice, this means
8768 that Gigi must make sure that such operations cannot be applied to
8769 non-BLKmode bit-fields.
8771 The second goal is achieved by means of the addressable_p predicate,
8772 which computes whether a temporary must be inserted by Gigi when the
8773 address of a tree is requested; if so, the address of the temporary
8774 will be used in lieu of that of the original tree and some glue code
8775 generated to connect everything together. */
8777 static bool
8779 {
8780 /* For an integral type, the size of the actual type of the object may not
8781 be greater than that of the expected type, otherwise an indirect access
8782 in the latter type wouldn't correctly set all the bits of the object. */
8788 /* The size of the actual type of the object may not be smaller than that
8789 of the expected type, otherwise an indirect access in the latter type
8790 would be larger than the object. But only record types need to be
8791 considered in practice for this case. */
8798 {
8803 /* All DECLs are addressable: if they are in a register, we can force
8804 them to memory. */
8809 /* Taking the address of a dereference yields the original pointer. */
8814 /* Taking the address yields a pointer to the constant pool. */
8818 /* Taking the address of a static constructor yields a pointer to the
8819 tree constant pool. */
8831 /* All rvalues are deemed addressable since taking their address will
8832 force a temporary to be created by the middle-end. */
8836 /* The address of a compound expression is that of its 2nd operand. */
8840 /* We accept &COND_EXPR as soon as both operands are addressable and
8841 expect the outcome to be the address of the selected operand. */
8847 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
8848 the field is sufficiently aligned, in case it is subject
8849 to a pragma Component_Alignment. But we don't need to
8850 check the alignment of the containing record, as it is
8851 guaranteed to be not smaller than that of its most
8852 aligned field that is not a bit-field. */
8853 && (!STRICT_ALIGNMENT
8856 /* The field of a padding record is always addressable. */
8870 {
8871 /* This is addressable if we can avoid a copy. */
8875 && (!STRICT_ALIGNMENT
8880 && (!STRICT_ALIGNMENT
8886 }
8890 }
8891 }
8892 \f
8893 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
8894 a separate Freeze node exists, delay the bulk of the processing. Otherwise
8895 make a GCC type for GNAT_ENTITY and set up the correspondence. */
8897 void
8899 {
8900 tree gnu_old
8902 tree gnu_new;
8904 /* If we are to delay elaboration of this type, just do any
8905 elaborations needed for expressions within the declaration and
8906 make a dummy type entry for this node and its Full_View (if
8907 any) in case something points to it. Don't do this if it
8908 has already been done (the only way that can happen is if
8909 the private completion is also delayed). */
8915 {
8919 {
8924 {
8928 }
8929 }
8932 }
8934 /* If we saved away a dummy type for this node it means that this
8935 made the type that corresponds to the full type of an incomplete
8936 type. Clear that type for now and then update the type in the
8937 pointers. */
8939 {
8944 }
8946 /* Now fully elaborate the type. */
8950 /* If we have an old type and we've made pointers to this type, update those
8951 pointers. If this is a Taft amendment type in the main unit, we need to
8952 mark the type as used since other units referencing it don't see the full
8953 declaration and, therefore, cannot mark it as used themselves. */
8955 {
8960 }
8962 /* If this is a record type corresponding to a task or protected type
8963 that is a completion of an incomplete type, perform a similar update
8964 on the type. ??? Including protected types here is a guess. */
8968 {
8969 tree gnu_task_old
8979 }
8980 }
8981 \f
8982 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
8983 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
8984 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
8986 static tree
8988 {
8991 /* We test for GNU_FIELD being empty in the case where a variant
8992 was the last thing since we don't take things off GNAT_ASSOC in
8993 that case. We check GNAT_ASSOC in case we have a variant, but it
8994 has no fields. */
8997 {
9002 /* The expander is supposed to put a single component selector name
9003 in every record component association. */
9006 /* Ignore fields that have Corresponding_Discriminants since we'll
9007 be setting that field in the parent. */
9012 /* Also ignore discriminants of Unchecked_Unions. */
9017 /* Before assigning a value in an aggregate make sure range checks
9018 are done if required. Then convert to the type of the field. */
9024 /* Add the field and expression to the list. */
9026 }
9030 #ifdef ENABLE_CHECKING
9031 /* Verify that every entry in GNU_LIST was used. */
9034 #endif
9037 }
9039 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9040 the first element of an array aggregate. It may itself be an aggregate.
9041 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9042 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9043 for range checking. */
9045 static tree
9047 Entity_Id gnat_component_type)
9048 {
9050 tree gnu_expr;
9054 {
9055 /* If the expression is itself an array aggregate then first build the
9056 innermost constructor if it is part of our array (multi-dimensional
9057 case). */
9063 gnat_component_type);
9064 else
9065 {
9068 /* Before assigning the element to the array, make sure it is
9069 in range. */
9072 }
9079 integer_one_node));
9080 }
9083 }
9084 \f
9085 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9086 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting
9087 of the associations that are from RECORD_TYPE. If we see an internal
9088 record, make a recursive call to fill it in as well. */
9090 static tree
9092 {
9097 {
9100 /* _Parent is an internal field, but may have values in the aggregate,
9101 so check for values first. */
9103 {
9106 }
9109 {
9114 }
9115 else
9116 /* If we have a record subtype, the names will match, but not the
9117 actual FIELD_DECLs. */
9120 {
9123 }
9129 }
9132 }
9133 \f
9134 /* Process a N_Validate_Unchecked_Conversion node. */
9136 static void
9138 {
9142 /* If the target is a pointer type, see if we are either converting from a
9143 non-pointer or from a pointer to a type with a different alias set and
9144 warn if so, unless the pointer has been marked to alias everything. */
9147 {
9157 target_alias_set)))
9158 {
9162 gnat_node);
9165 }
9166 }
9168 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9169 mitigate the problem in this case, so we unconditionally warn. */
9171 {
9172 tree gnu_source_desig_type
9176 tree gnu_target_desig_type
9183 target_alias_set)))
9184 {
9188 gnat_node);
9189 }
9190 }
9191 }
9192 \f
9193 /* EXP is to be treated as an array or record. Handle the cases when it is
9194 an access object and perform the required dereferences. */
9196 static tree
9198 {
9199 /* If the type is a pointer, dereference it. */
9204 /* If we got a padded type, remove it too. */
9209 }
9210 \f
9211 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9212 location and false if it doesn't. In the former case, set the Gigi global
9213 variable REF_FILENAME to the simple debug file name as given by sinput.
9214 If clear_column is true, set column information to 0. */
9216 static bool
9218 {
9223 {
9226 }
9227 else
9228 {
9234 /* We can have zero if pragma Source_Reference is in effect. */
9238 /* Translate the location. */
9240 }
9242 ref_filename
9243 = IDENTIFIER_POINTER
9244 (get_identifier
9248 }
9250 /* Similar to the above, not clearing the column information. */
9252 bool
9254 {
9256 }
9258 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9259 don't do anything if it doesn't correspond to a source location. */
9261 static void
9263 {
9264 location_t locus;
9270 }
9272 /* Similar to the above, not clearing the column information. */
9274 static void
9276 {
9278 }
9280 /* More elaborate version of set_expr_location_from_node to be used in more
9281 general contexts, for example the result of the translation of a generic
9282 GNAT node. */
9284 static void
9286 {
9287 /* Set the location information on the node if it is a real expression.
9288 References can be reused for multiple GNAT nodes and they would get
9289 the location information of their last use. Also make sure not to
9290 overwrite an existing location as it is probably more precise. */
9293 {
9294 CASE_CONVERT:
9303 /* ... fall through ... */
9307 {
9310 }
9312 }
9313 }
9314 \f
9315 /* Return a colon-separated list of encodings contained in encoded Ada
9316 name. */
9320 {
9324 }
9326 /* Extract the Ada name from an encoded name. */
9330 {
9334 }
9335 \f
9336 /* Post an error message. MSG is the error message, properly annotated.
9337 NODE is the node at which to post the error and the node to use for the
9338 '&' substitution. */
9340 void
9342 {
9343 String_Template temp;
9344 String_Pointer sp;
9354 }
9356 /* Similar to post_error, but NODE is the node at which to post the error and
9357 ENT is the node to use for the '&' substitution. */
9359 void
9361 {
9362 String_Template temp;
9363 String_Pointer sp;
9373 }
9375 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
9377 void
9379 {
9382 }
9384 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9385 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9386 most sense. Return true if a sensible assignment was performed. */
9388 static bool
9390 {
9392 location_t end_locus;
9394 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9395 end_locus when there is one. We consider only GNAT nodes with a possible
9396 End_Label attached. If the End_Label actually was unassigned, fallback
9397 on the original node. We'd better assign an explicit sloc associated with
9398 the outer construct in any case. */
9401 {
9414 }
9418 /* Some expanded subprograms have neither an End_Label nor a Sloc
9419 attached. Notify that to callers. For a block statement with no
9420 End_Label, clear column information, so that the tree for a
9421 transient block does not receive the sloc of a source condition. */
9429 {
9440 }
9441 }
9442 \f
9443 /* Similar to post_error_ne, but T is a GCC tree representing the number to
9444 write. If T represents a constant, the text inside curly brackets in
9445 MSG will be output (presumably including a '^'). Otherwise it will not
9446 be output and the text inside square brackets will be output instead. */
9448 void
9450 {
9457 {
9460 }
9461 else
9465 {
9471 ;
9472 else
9474 }
9479 }
9481 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
9483 void
9486 {
9489 }
9490 \f
9491 /* Initialize the table that maps GNAT codes to GCC codes for simple
9492 binary and unary operations. */
9494 static void
9496 {
9522 }
9524 /* Return a label to branch to for the exception type in KIND or NULL_TREE
9525 if none. */
9527 tree
9529 {
9536 else
9538 }
9540 /* Return the decl for the current elaboration procedure. */
9542 tree
9544 {
9546 }