| blob | bb3dfa9f2e63cc879ff294d89d26b36f8c9a03b5 |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2015, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License distributed with GNAT; see file COPYING3. If not see *
19 * <http://www.gnu.org/licenses/>. *
20 * *
21 * GNAT was originally developed by the GNAT team at New York University. *
22 * Extensive contributions were provided by Ada Core Technologies Inc. *
23 * *
24 ****************************************************************************/
84 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
85 for fear of running out of stack space. If we need more, we use xmalloc
86 instead. */
87 #define ALLOCA_THRESHOLD 1000
89 /* In configurations where blocks have no end_locus attached, just
90 sink assignments into a dummy global. */
91 #ifndef BLOCK_SOURCE_END_LOCATION
93 #define BLOCK_SOURCE_END_LOCATION(BLOCK) block_end_locus_sink
94 #endif
96 /* Pointers to front-end tables accessed through macros. */
107 /* Highest number in the front-end node table. */
110 /* Current node being treated, in case abort called. */
111 Node_Id error_gnat_node;
113 /* True when gigi is being called on an analyzed but unexpanded
114 tree, and the only purpose of the call is to properly annotate
115 types with representation information. */
118 /* Current filename without path. */
122 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
125 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
126 of unconstrained array IN parameters to avoid emitting a great deal of
127 redundant instructions to recompute them each time. */
131 tree first;
132 tree last;
133 tree length;
134 };
141 bitmap named_ret_val;
144 };
146 #define f_parm_attr_cache \
147 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
149 #define f_named_ret_val \
150 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
152 #define f_other_ret_val \
153 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
155 #define f_gnat_ret \
156 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
158 /* A structure used to gather together information about a statement group.
159 We use this to gather related statements, for example the "then" part
160 of a IF. In the case where it represents a lexical scope, we may also
161 have a BLOCK node corresponding to it and/or cleanups. */
168 };
172 /* List of unused struct stmt_group nodes. */
175 /* A structure used to record information on elaboration procedures
176 we've made and need to process.
178 ??? gnat_node should be Node_Id, but gengtype gets confused. */
184 };
188 /* Stack of exception pointer variables. Each entry is the VAR_DECL
189 that stores the address of the raised exception. Nonzero means we
190 are in an exception handler. Not used in the zero-cost case. */
193 /* In ZCX case, current exception pointer. Used to re-raise it. */
196 /* Stack for storing the current elaboration procedure decl. */
199 /* Stack of labels to be used as a goto target instead of a return in
200 some functions. See processing for N_Subprogram_Body. */
203 /* Stack of variable for the return value of a function with copy-in/copy-out
204 parameters. See processing for N_Subprogram_Body. */
207 /* Structure used to record information for a range check. */
209 tree low_bound;
210 tree high_bound;
211 tree type;
212 tree invariant_cond;
213 };
218 /* Structure used to record information for a loop. */
220 tree stmt;
221 tree loop_var;
223 };
228 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
231 /* The stacks for N_{Push,Pop}_*_Label. */
236 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
273 /* Hooks for debug info back-ends, only supported and used in a restricted set
274 of configurations. */
277 \f
278 /* This is the main program of the back-end. It sets up all the table
279 structures and then generates code. */
281 void
294 Nat number_file,
296 Entity_Id standard_boolean,
297 Entity_Id standard_integer,
298 Entity_Id standard_character,
299 Entity_Id standard_long_long_float,
300 Entity_Id standard_exception_type,
301 Int gigi_operating_mode)
302 {
303 Node_Id gnat_iter;
304 Entity_Id gnat_literal;
324 {
325 /* Use the identifier table to make a permanent copy of the filename as
326 the name table gets reallocated after Gigi returns but before all the
327 debugging information is output. The __gnat_to_canonical_file_spec
328 call translates filenames from pragmas Source_Reference that contain
329 host style syntax not understood by gdb. */
331 = IDENTIFIER_POINTER
332 (get_identifier
333 (__gnat_to_canonical_file_spec
336 /* We rely on the order isomorphism between files and line maps. */
339 /* We create the line map for a source file at once, with a fixed number
340 of columns chosen to avoid jumping over the next power of 2. */
345 }
349 /* Declare the name of the compilation unit as the first global
350 name in order to make the middle-end fully deterministic. */
354 /* Initialize ourselves. */
359 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
360 errors. */
362 {
365 }
367 /* Enable GNAT stack checking method if needed */
371 /* Retrieve alignment settings. */
375 /* Record the builtin types. Define `integer' and `character' first so that
376 dbx will output them first. */
382 /* Save the type we made for integer as the type for Standard.Integer. */
387 /* Likewise for character as the type for Standard.Character. */
392 /* Likewise for boolean as the type for Standard.Boolean. */
416 /* Now declare run-time functions. */
419 /* malloc is a function declaration tree for a function to allocate
420 memory. */
421 malloc_decl
427 /* free is a function declaration tree for a function to free memory. */
428 free_decl
431 ptr_void_type_node,
432 NULL_TREE),
434 Empty);
436 /* This is used for 64-bit multiplication with overflow checking. */
438 mulv64_decl
443 Empty);
445 /* Name of the _Parent field in tagged record types. */
448 /* Name of the Exception_Data type defined in System.Standard_Library. */
449 exception_data_name_id
452 /* Make the types and functions used for exception processing. */
453 jmpbuf_type
459 /* Functions to get and set the jumpbuf pointer for the current thread. */
460 get_jmpbuf_decl
461 = create_subprog_decl
467 set_jmpbuf_decl
468 = create_subprog_decl
471 NULL_TREE),
475 /* setjmp returns an integer and has one operand, which is a pointer to
476 a jmpbuf. */
477 setjmp_decl
478 = create_subprog_decl
481 NULL_TREE),
486 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
487 address. */
488 update_setjmp_buf_decl
489 = create_subprog_decl
496 /* Hooks to call when entering/leaving an exception handler. */
497 ftype
500 begin_handler_decl
506 end_handler_decl
512 unhandled_except_decl
514 NULL_TREE,
519 reraise_zcx_decl
523 /* Indicate that these never return. */
530 /* If in no exception handlers mode, all raise statements are redirected to
531 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
532 this procedure will never be called in this mode. */
534 {
535 tree decl
536 = create_subprog_decl
539 build_pointer_type
549 }
550 else
551 {
552 /* Otherwise, make one decl for each exception reason. */
558 i == CE_Index_Check_Failed
562 }
564 /* Set the types that GCC and Gigi use from the front end. */
567 /* Make other functions used for exception processing. */
568 get_excptr_decl
569 = create_subprog_decl
572 NULL_TREE),
576 set_exception_parameter_decl
577 = create_subprog_decl
580 ptr_void_type_node,
581 ptr_void_type_node,
582 NULL_TREE),
585 raise_nodefer_decl
586 = create_subprog_decl
590 NULL_TREE),
593 /* Indicate that it never returns. */
598 TYPE_QUAL_VOLATILE);
600 /* Build the special descriptor type and its null node if needed. */
602 {
614 {
615 tree field
622 elt--;
623 }
628 }
630 longest_float_type_node
633 /* Dummy objects to materialize "others" and "all others" in the exception
634 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
635 the types to use. */
636 others_decl
639 unsigned_char_type_node,
642 all_others_decl
645 unsigned_char_type_node,
648 unhandled_others_decl
651 unsigned_char_type_node,
656 /* Install the builtins we might need, either internally or as
657 user available facilities for Intrinsic imports. */
665 /* Process any Pragma Ident for the main unit. */
670 /* If we are using the GCC exception mechanism, let GCC know. */
674 /* Initialize the GCC support for FP operations. */
677 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
681 /* Save the current optimization options again after the above possible
682 global_options changes. */
686 /* Now translate the compilation unit proper. */
689 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
690 the very end to avoid having to second-guess the front-end when we run
691 into dummy nodes during the regular processing. */
696 /* Finally see if we have any elaboration procedures to deal with. */
698 {
701 /* We should have a BIND_EXPR but it may not have any statements in it.
702 If it doesn't have any, we have nothing to do except for setting the
703 flag on the GNAT node. Otherwise, process the function as others. */
709 else
710 {
714 }
715 }
717 /* Destroy ourselves. */
721 /* We cannot track the location of errors past this point. */
723 }
724 \f
725 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
726 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
728 static tree
730 {
739 {
741 ftype
743 build_pointer_type
746 }
747 else
748 {
753 ftype
755 build_pointer_type
759 }
761 result
766 /* Indicate that it never returns. */
773 }
774 \f
775 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
776 an N_Attribute_Reference. */
778 static int
780 {
782 {
822 }
823 }
825 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
826 is the type that will be used for GNAT_NODE in the translated GNU tree.
827 CONSTANT indicates whether the underlying object represented by GNAT_NODE
828 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
829 whether its value is the address of a constant and ALIASED whether it is
830 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
832 The function climbs up the GNAT tree starting from the node and returns 1
833 upon encountering a node that effectively requires an lvalue downstream.
834 It returns int instead of bool to facilitate usage in non-purely binary
835 logic contexts. */
837 static int
840 {
844 {
854 /* If the parameter is by reference, an lvalue is required. */
860 /* Only the array expression can require an lvalue. */
864 /* ??? Consider that referencing an indexed component with a
865 non-constant index forces the whole aggregate to memory.
866 Note that N_Integer_Literal is conservative, any static
867 expression in the RM sense could probably be accepted. */
874 /* ... fall through ... */
877 /* Only the array expression can require an lvalue. */
891 /* We need to preserve addresses through a renaming. */
895 /* We cannot use a constructor if this is an atomic object because
896 the actual assignment might end up being done component-wise. */
900 /* We don't use a constructor if this is a class-wide object
901 because the effective type of the object is the equivalent
902 type of the class-wide subtype and it smashes most of the
903 data into an array of bytes to which we cannot convert. */
908 /* We cannot use a constructor if the LHS is an atomic object because
909 the actual assignment might end up being done component-wise. */
919 /* ... fall through ... */
923 /* We must look through all conversions because we may need to bypass
924 an intermediate conversion that is meant to be purely formal. */
930 /* We should only reach here through the N_Qualified_Expression case.
931 Force an lvalue for composite types since a block-copy to the newly
932 allocated area of memory is made. */
936 /* We look through dereferences for address of constant because we need
937 to handle the special cases listed above. */
943 /* ... fall through ... */
947 }
950 }
952 /* Return true if T is a constant DECL node that can be safely replaced
953 by its initializer. */
955 static bool
957 {
961 /* Return false for aggregate types that contain a placeholder since
962 their initializers cannot be manipulated easily. */
969 }
971 /* Return an expression equivalent to EXP but where constant DECL nodes
972 have been replaced by their initializer. */
974 static tree
976 {
978 tree op0;
981 {
1018 }
1021 }
1023 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1024 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1025 to where we should place the result type. */
1027 static tree
1029 {
1033 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1034 specific circumstances only, so evaluated lazily. < 0 means
1035 unknown, > 0 means known true, 0 means known false. */
1038 /* If GNAT_NODE is a constant, whether we should use the initialization
1039 value instead of the constant entity, typically for scalars with an
1040 address clause when the parent doesn't require an lvalue. */
1043 /* If the Etype of this node does not equal the Etype of the Entity,
1044 something is wrong with the entity map, probably in generic
1045 instantiation. However, this does not apply to types. Since we sometime
1046 have strange Ekind's, just do this test for objects. Also, if the Etype of
1047 the Entity is private, the Etype of the N_Identifier is allowed to be the
1048 full type and also we consider a packed array type to be the same as the
1049 original type. Similarly, a class-wide type is equivalent to a subtype of
1050 itself. Finally, if the types are Itypes, one may be a copy of the other,
1051 which is also legal. */
1066 == Packed_Array_Impl_Type
1075 /* If this is a reference to a deferred constant whose partial view is an
1076 unconstrained private type, the proper type is on the full view of the
1077 constant, not on the full view of the type, which may be unconstrained.
1079 This may be a reference to a type, for example in the prefix of the
1080 attribute Position, generated for dispatching code (see Make_DT in
1081 exp_disp,adb). In that case we need the type itself, not is parent,
1082 in particular if it is a derived type */
1089 {
1092 }
1093 else
1094 {
1095 /* We want to use the Actual_Subtype if it has already been elaborated,
1096 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1097 simplify things. */
1105 else
1107 }
1109 /* Expand the type of this identifier first, in case it is an enumeral
1110 literal, which only get made when the type is expanded. There is no
1111 order-of-elaboration issue here. */
1114 /* If this is a non-imported elementary constant with an address clause,
1115 retrieve the value instead of a pointer to be dereferenced unless
1116 an lvalue is required. This is generally more efficient and actually
1117 required if this is a static expression because it might be used
1118 in a context where a dereference is inappropriate, such as a case
1119 statement alternative or a record discriminant. There is no possible
1120 volatile-ness short-circuit here since Volatile constants must be
1121 imported per C.6. */
1126 {
1130 }
1133 {
1134 /* If this is a deferred constant, the initializer is attached to
1135 the full view. */
1140 }
1141 else
1144 /* Some objects (such as parameters passed by reference, globals of
1145 variable size, and renamed objects) actually represent the address
1146 of the object. In that case, we must do the dereference. Likewise,
1147 deal with parameters to foreign convention subprograms. */
1152 {
1155 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1158 gnu_result
1161 /* If it's a CONST_DECL, return the underlying constant like below. */
1168 /* If it's a renaming pointer and, either the renamed object is constant
1169 or we are at the right binding level, we can reference the renamed
1170 object directly, since it is constant or has been protected against
1171 multiple evaluations. */
1180 /* Otherwise, do the final dereference. */
1181 else
1182 {
1192 }
1193 }
1195 /* If we have a constant declaration and its initializer, try to return the
1196 latter to avoid the need to call fold in lots of places and the need for
1197 elaboration code if this identifier is used as an initializer itself. */
1199 {
1205 /* If there is a (corresponding) variable or this is the address of a
1206 constant, we only want to return the initializer if an lvalue isn't
1207 required. Evaluate this now if we have not already done so. */
1209 require_lvalue
1213 /* Finally retrieve the initializer if this is deemed valid. */
1216 }
1218 /* But for a constant renaming we couldn't do that incrementally for its
1219 definition because of the need to return an lvalue so, if the present
1220 context doesn't itself require an lvalue, we try again here. */
1224 {
1226 require_lvalue
1231 }
1233 /* The GNAT tree has the type of a function set to its result type, so we
1234 adjust here. Also use the type of the result if the Etype is a subtype
1235 that is nominally unconstrained. Likewise if this is a deferred constant
1236 of a discriminated type whose full view can be elaborated statically, to
1237 avoid problematic conversions to the nominal subtype. But remove any
1238 padding from the resulting type. */
1245 {
1249 }
1254 }
1255 \f
1256 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1257 any statements we generate. */
1259 static tree
1261 {
1264 Node_Id gnat_temp;
1266 /* Do nothing if we are just annotating types and check for (and ignore)
1267 unrecognized pragmas. */
1274 {
1276 /* Do nothing at top level: all such variables are already viewable. */
1283 {
1287 machine_mode mode;
1289 #ifdef ASM_COMMENT_START
1291 #endif
1296 /* Use the value only if it fits into a normal register,
1297 otherwise use the address. */
1306 #ifdef ASM_COMMENT_START
1312 NULL);
1315 #endif
1317 asm_constraint,
1318 NULL_TREE,
1319 tree_cons
1327 }
1334 {
1338 {
1361 }
1362 }
1368 {
1386 }
1396 {
1397 Node_Id gnat_expr;
1398 /* Preserve the location of the pragma. */
1402 diagnostic_t kind;
1407 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1409 {
1411 {
1424 }
1427 }
1429 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1431 {
1433 {
1444 }
1446 /* Deal with optional pattern (but ignore Reason => "..."). */
1449 {
1450 /* pragma Warnings (On | Off, Name) is handled differently. */
1455 }
1456 else
1460 }
1462 else
1465 /* This is the same implementation as in the C family of compilers. */
1467 {
1475 option_index++)
1479 {
1482 }
1483 }
1484 else
1491 }
1496 }
1499 }
1500 \f
1502 /* Check the inlining status of nested function FNDECL in the current context.
1504 If a non-inline nested function is referenced from an inline external
1505 function, we cannot honor both requests at the same time without cloning
1506 the nested function in the current unit since it is private to its unit.
1507 We could inline it as well but it's probably better to err on the side
1508 of too little inlining.
1510 This must be invoked only on nested functions present in the source code
1511 and not on nested functions generated by the compiler, e.g. finalizers,
1512 because they are not marked inline and we don't want them to block the
1513 inlining of the parent function. */
1515 static void
1517 {
1519 && current_function_decl
1522 {
1528 {
1531 }
1532 else
1533 {
1535 fndecl);
1537 }
1541 }
1542 }
1543 \f
1544 /* Return an expression for the length of TYPE, an integral type, computed in
1545 RESULT_TYPE, another integral type.
1547 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1548 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1549 which would only overflow in much rarer cases, for extremely large arrays
1550 we expect never to encounter in practice. Besides, the former computation
1551 required the use of potentially constraining signed arithmetics while the
1552 latter does not. Note that the comparison must be done in the original
1553 base index type in order to avoid any overflow during the conversion. */
1555 static tree
1557 {
1562 tree length
1568 length
1574 }
1576 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1577 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1578 where we should place the result type. ATTRIBUTE is the attribute ID. */
1580 static tree
1582 {
1588 /* ??? If this is an access attribute for a public subprogram to be used in
1589 a dispatch table, do not translate its type as it's useless in this case
1590 and the parameter types might be incomplete types coming from a limited
1591 context in Ada 2012 (AI05-0151). */
1599 else
1603 /* If the input is a NULL_EXPR, make a new one. */
1605 {
1609 }
1612 {
1615 /* These are just conversions since representation clauses for
1616 enumeration types are handled in the front-end. */
1617 {
1623 }
1628 /* These just add or subtract the constant 1 since representation
1629 clauses for enumeration types are handled in the front-end. */
1634 {
1636 gnu_expr
1637 = emit_check
1639 gnu_expr,
1640 attribute == Attr_Pred
1644 }
1646 gnu_result
1654 /* Conversions don't change addresses but can cause us to miss the
1655 COMPONENT_REF case below, so strip them off. */
1659 /* If we are taking 'Address of an unconstrained object, this is the
1660 pointer to the underlying array. */
1664 /* If we are building a static dispatch table, we have to honor
1665 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1666 with the C++ ABI. We do it in the non-static case as well,
1667 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1670 {
1672 /* Descriptors can only be built here for top-level functions. */
1680 /* If we're not going to build the descriptor, we have to retrieve
1681 the one which will be built by the linker (or by the compiler
1682 later if a static chain is requested). */
1684 {
1687 gnu_result);
1689 }
1696 {
1698 {
1702 }
1703 else
1709 elt--;
1710 }
1714 }
1716 /* ... fall through ... */
1722 gnu_result
1729 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1730 don't try to build a trampoline. */
1732 {
1737 }
1739 /* For 'Access, issue an error message if the prefix is a C++ method
1740 since it can use a special calling convention on some platforms,
1741 which cannot be propagated to the access type. */
1746 gnat_node);
1748 /* For other address attributes applied to a nested function,
1749 find an inner ADDR_EXPR and annotate it so that we can issue
1750 a useful warning with -Wtrampolines. */
1752 {
1757 {
1760 /* Also check the inlining status. */
1763 /* Check that we're not violating the No_Implicit_Dynamic_Code
1764 restriction. Be conservative if we don't know anything
1765 about the trampoline strategy for the target. */
1767 }
1768 }
1772 {
1774 tree gnu_obj_type;
1778 /* If this is fat pointer, the object must have been allocated with the
1779 template in front of the array. So compute the template address; do
1780 it by converting to a thin pointer. */
1782 gnu_ptr
1784 (TYPE_OBJECT_RECORD_TYPE
1786 gnu_ptr);
1790 /* If this is a thin pointer, the object must have been allocated with
1791 the template in front of the array. So compute the template address
1792 and return it. */
1794 gnu_ptr
1796 gnu_ptr,
1798 byte_position
1799 (DECL_CHAIN
1803 }
1812 /* Remove NOPs and conversions between original and packable version
1813 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1814 to see if a COMPONENT_REF was involved. */
1819 == RECORD_TYPE
1828 /* Replace an unconstrained array type with the type of the underlying
1829 array. We can't do this with a call to maybe_unconstrained_array
1830 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1831 use the record type that will be used to allocate the object and its
1832 template. */
1834 {
1838 }
1840 /* If we're looking for the size of a field, return the field size. */
1844 /* Otherwise, if the prefix is an object, or if we are looking for
1845 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1846 GCC size of the type. We make an exception for padded objects,
1847 as we do not take into account alignment promotions for the size.
1848 This is in keeping with the object case of gnat_to_gnu_entity. */
1854 {
1855 /* If this is a dereference and we have a special dynamic constrained
1856 subtype on the prefix, use it to compute the size; otherwise, use
1857 the designated subtype. */
1859 {
1860 Node_Id gnat_actual_subtype
1862 tree gnu_ptr_type
1867 {
1868 tree gnu_actual_obj_type
1870 gnu_type
1872 gnu_actual_obj_type,
1875 }
1876 }
1879 }
1881 /* Otherwise, the result is the RM size of the type. */
1882 else
1885 /* Deal with a self-referential size by returning the maximum size for
1886 a type and by qualifying the size with the object otherwise. */
1888 {
1891 else
1893 }
1895 /* If the type contains a template, subtract its size. */
1901 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1909 {
1922 else
1923 {
1928 /* If the default alignment of "double" or larger scalar types is
1929 specifically capped and there is an alignment clause neither
1930 on the type nor on the prefix itself, return the cap. */
1932 is_capped_double
1935 is_capped_double
1937 else
1947 else
1949 }
1952 }
1961 {
1968 else
1971 }
1973 /* ... fall through ... */
1976 {
1984 /* Make sure any implicit dereference gets done. */
1988 /* We treat unconstrained array In parameters specially. We also note
1989 whether we are dereferencing a pointer to unconstrained array. */
1992 {
1994 /* This is the direct case. */
2000 /* This is the indirect case. Note that we need to be sure that
2001 the access value cannot be null as we'll hoist the load. */
2004 {
2007 }
2008 else
2014 }
2016 /* If the prefix is the view conversion of a constrained array to an
2017 unconstrained form, we retrieve the constrained array because we
2018 might not be able to substitute the PLACEHOLDER_EXPR coming from
2019 the conversion. This can occur with the 'Old attribute applied
2020 to a parameter with an unconstrained type, which gets rewritten
2021 into a constrained local variable very late in the game. */
2024 && !CONTAINS_PLACEHOLDER_P
2027 else
2034 {
2036 tree gnu_type_temp;
2042 ;
2045 }
2052 /* When not optimizing, look up the slot associated with the parameter
2053 and the dimension in the cache and create a new one on failure.
2054 Don't do this when the actual subtype needs debug info (this happens
2055 with -gnatD): in elaborate_expression_1, we create variables that
2056 hold the bounds, so caching attributes isn't very interesting and
2057 causes dependency issues between these variables and cached
2058 expressions. */
2063 {
2069 {
2074 }
2075 }
2077 /* Return the cached expression or build a new one. */
2079 {
2081 {
2084 }
2086 gnu_result
2088 }
2091 {
2093 {
2096 }
2098 gnu_result
2100 }
2103 {
2105 {
2108 }
2110 gnu_result
2112 gnu_result_type);
2113 }
2115 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2116 handling. Note that these attributes could not have been used on
2117 an unconstrained array type. */
2120 /* Cache the expression we have just computed. Since we want to do it
2121 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2122 create the temporary in the outermost binding level. We will make
2123 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2124 paths by forcing its evaluation on entry of the function. */
2126 {
2127 gnu_result
2130 {
2146 }
2147 }
2149 /* Otherwise, evaluate it each time it is referenced. */
2150 else
2152 {
2155 /* If we are dereferencing a pointer to unconstrained array, we
2156 need to capture the value because the pointed-to bounds may
2157 subsequently be released. */
2159 gnu_result
2165 /* Set the source location onto the predicate of the condition
2166 but not if the expression is cached to avoid messing up the
2167 debug info. */
2171 gnat_node);
2176 }
2179 }
2186 {
2187 HOST_WIDE_INT bitsize;
2188 HOST_WIDE_INT bitpos;
2189 tree gnu_offset;
2190 tree gnu_field_bitpos;
2191 tree gnu_field_offset;
2192 tree gnu_inner;
2193 machine_mode mode;
2200 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2201 the result is 0. Don't allow 'Bit on a bare component, though. */
2205 {
2208 }
2210 else
2219 {
2227 {
2228 gnu_field_bitpos
2231 gnu_field_offset
2234 }
2235 }
2237 {
2240 }
2241 else
2242 {
2245 }
2248 {
2262 /* ??? Avoid a large unsigned result that will overflow when
2263 converted to the signed universal_integer. */
2266 else
2267 gnu_result
2274 }
2276 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2277 handling. */
2280 }
2284 {
2290 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2291 a NaN so we implement the semantics of C99 f{min,max} to make it
2292 predictable in this case: if either operand is a NaN, the other
2293 is returned; if both operands are NaN's, a NaN is returned. */
2295 {
2301 /* If the operands have side-effects, they need to be evaluated
2302 only once in spite of the multiple references in the result. */
2310 integer_zero_node);
2314 integer_zero_node);
2324 /* If the operands have side-effects, they need to be evaluated
2325 before doing the tests above since the place they otherwise
2326 would end up being evaluated at run time could be wrong. */
2328 gnu_result
2332 gnu_result
2334 }
2335 else
2339 }
2365 /* Note this size cannot be self-referential. */
2375 /* What we want is the offset of the ARRAY field in the record
2376 that the thin pointer designates. */
2384 /* This is just a zero cast to the pointer type for our prefix and
2385 dereferenced. */
2387 gnu_result
2390 integer_zero_node));
2395 {
2402 {
2407 ;
2408 }
2416 && (DECL_BY_COMPONENT_PTR_P
2420 }
2424 /* We treat Model as identical to Machine. This is true for at least
2425 IEEE and some other nice floating-point systems. */
2427 /* ... fall through ... */
2430 /* The trick is to force the compiler to store the result in memory so
2431 that we do not have extra precision used. But do this only when this
2432 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2433 the type is lower than that of the longest floating-point type. */
2442 {
2444 tree field
2454 asm_expr
2466 gnu_result
2470 }
2477 /* This can be a random address so build an alias-all pointer type. */
2478 gnu_expr
2481 gnu_expr);
2486 /* This abort means that we have an unimplemented attribute. */
2488 }
2490 /* If this is an attribute where the prefix was unused, force a use of it if
2491 it has a side-effect. But don't do it if the prefix is just an entity
2492 name. However, if an access check is needed, we must do it. See second
2493 example in AARM 11.6(5.e). */
2497 gnu_result
2502 }
2503 \f
2504 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2505 to a GCC tree, which is returned. */
2507 static tree
2509 {
2511 Node_Id gnat_when;
2512 location_t end_locus;
2518 /* The range of values in a case statement is determined by the rules in
2519 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2520 of the expression. One exception arises in the case of a simple name that
2521 is parenthesized. This still has the Etype of the name, but since it is
2522 not a name, para 7 does not apply, and we need to go to the base type.
2523 This is the only case where parenthesization affects the dynamic
2524 semantics (i.e. the range of possible values at run time that is covered
2525 by the others alternative).
2527 Another exception is if the subtype of the expression is non-static. In
2528 that case, we also have to use the base type. */
2534 /* We build a SWITCH_EXPR that contains the code with interspersed
2535 CASE_LABEL_EXPRs for each label. */
2544 {
2546 Node_Id gnat_choice;
2548 /* First compile all the different case choices for the current WHEN
2549 alternative. */
2553 {
2558 {
2573 /* This represents either a subtype range or a static value of
2574 some kind; Ekind says which. */
2576 {
2582 }
2584 /* ... fall through ... */
2596 }
2598 /* Everything should be folded into constants at this point. */
2603 gnat_choice);
2605 }
2607 /* This construct doesn't define a scope so we shouldn't push a binding
2608 level around the statement list. Except that we have always done so
2609 historically and this makes it possible to reduce stack usage. As a
2610 compromise, we keep doing it for case statements, for which this has
2611 never been problematic, but not for case expressions in Ada 2012. */
2613 {
2614 const bool is_case_expression
2616 tree group
2621 {
2626 }
2627 }
2628 }
2630 /* Now emit a definition of the label the cases branch to, if any. */
2637 }
2638 \f
2639 /* Find out whether VAR is an iteration variable of an enclosing loop in the
2640 current function. If so, push a range_check_info structure onto the stack
2641 of this enclosing loop and return it. Otherwise, return NULL. */
2645 {
2661 i--)
2666 {
2670 }
2673 }
2675 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2676 false, or the maximum value if MAX is true, of TYPE. */
2678 static bool
2680 {
2687 val = (max
2696 else
2698 }
2700 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2701 If REVERSE is true, minimum value is taken as maximum value. */
2705 {
2707 }
2709 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2710 If REVERSE is true, maximum value is taken as minimum value. */
2714 {
2716 }
2718 /* Return true if VAL1 can be lower than VAL2. */
2720 static bool
2722 {
2736 }
2738 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2739 to a GCC tree, which is returned. */
2741 static tree
2743 {
2750 tree gnu_result;
2752 /* Push the loop_info structure associated with the LOOP_STMT. */
2755 /* Set location information for statement and end label. */
2761 /* Save the statement for later reuse. */
2764 /* Set the condition under which the loop must keep going.
2765 For the case "LOOP .... END LOOP;" the condition is always true. */
2767 ;
2769 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2774 /* Otherwise we have an iteration scheme and the condition is given by the
2775 bounds of the subtype of the iteration variable. */
2776 else
2777 {
2791 /* We must disable modulo reduction for the iteration variable, if any,
2792 in order for the loop comparison to be effective. */
2794 {
2800 }
2801 else
2802 {
2808 }
2810 /* We use two different strategies to translate the loop, depending on
2811 whether optimization is enabled.
2813 If it is, we generate the canonical loop form expected by the loop
2814 optimizer and the loop vectorizer, which is the do-while form:
2816 ENTRY_COND
2817 loop:
2818 TOP_UPDATE
2819 BODY
2820 BOTTOM_COND
2821 GOTO loop
2823 This avoids an implicit dependency on loop header copying and makes
2824 it possible to turn BOTTOM_COND into an inequality test.
2826 If optimization is disabled, loop header copying doesn't come into
2827 play and we try to generate the loop form with the fewer conditional
2828 branches. First, the default form, which is:
2830 loop:
2831 TOP_COND
2832 BODY
2833 BOTTOM_UPDATE
2834 GOTO loop
2836 It should catch most loops with constant ending point. Then, if we
2837 cannot, we try to generate the shifted form:
2839 loop:
2840 TOP_COND
2841 TOP_UPDATE
2842 BODY
2843 GOTO loop
2845 which should catch loops with constant starting point. Otherwise, if
2846 we cannot, we generate the fallback form:
2848 ENTRY_COND
2849 loop:
2850 BODY
2851 BOTTOM_COND
2852 BOTTOM_UPDATE
2853 GOTO loop
2855 which works in all cases. */
2858 {
2859 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2860 overflow. */
2862 ;
2864 /* Otherwise, use the do-while form with the help of a special
2865 induction variable in the unsigned version of the base type
2866 or the unsigned version of the size type, whichever is the
2867 largest, in order to have wrap-around arithmetics for it. */
2868 else
2869 {
2872 gnu_base_type
2874 else
2881 }
2883 gnu_first
2885 gnu_one_node);
2888 }
2889 else
2890 {
2891 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2893 ;
2895 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2896 GNU_LAST-1 does. */
2899 {
2900 gnu_first
2902 gnu_one_node);
2903 gnu_last
2905 gnu_one_node);
2907 }
2909 /* Otherwise, use the fallback form. */
2910 else
2912 }
2914 /* If we use the BOTTOM_COND, we can turn the test into an inequality
2915 test but we may have to add ENTRY_COND to protect the empty loop. */
2917 {
2920 {
2921 gnu_cond_expr
2927 }
2928 }
2930 /* Open a new nesting level that will surround the loop to declare the
2931 iteration variable. */
2935 /* If we use the special induction variable, create it and set it to
2936 its initial value. Morever, the regular iteration variable cannot
2937 itself be initialized, lest the initial value wrapped around. */
2939 {
2940 gnu_loop_iv
2944 }
2945 else
2948 /* Declare the iteration variable and set it to its initial value. */
2953 {
2956 }
2959 /* Do all the arithmetics in the base type. */
2962 /* Set either the top or bottom exit condition. */
2966 gnu_last);
2967 else
2970 gnu_last);
2972 /* Set either the top or bottom update statement and give it the source
2973 location of the iteration for better coverage info. */
2975 {
2976 gnu_stmt
2983 gnu_stmt
2985 gnu_loop_iv);
2989 }
2990 else
2991 {
2992 gnu_stmt
2998 }
2999 }
3001 /* If the loop was named, have the name point to this loop. In this case,
3002 the association is not a DECL node, but the end label of the loop. */
3006 /* Make the loop body into its own block, so any allocated storage will be
3007 released every iteration. This is needed for stack allocation. */
3012 /* If we have an iteration scheme, then we are in a statement group. Add
3013 the LOOP_STMT to it, finish it and make it the "loop". */
3015 {
3020 /* First, if we have computed a small number of invariant conditions for
3021 range checks applied to the iteration variable, then initialize these
3022 conditions in front of the loop. Otherwise, leave them set to true.
3024 ??? The heuristics need to be improved, by taking into account the
3025 following datapoints:
3026 - loop unswitching is disabled for big loops. The cap is the
3027 parameter PARAM_MAX_UNSWITCH_INSNS (50).
3028 - loop unswitching can only be applied a small number of times
3029 to a given loop. The cap is PARAM_MAX_UNSWITCH_LEVEL (3).
3030 - the front-end quickly generates useless or redundant checks
3031 that can be entirely optimized away in the end. */
3035 i++)
3036 {
3037 tree low_ok
3044 tree high_ok
3051 tree range_ok
3059 }
3064 }
3066 /* If we have an outer COND_EXPR, that's our result and this loop is its
3067 "true" statement. Otherwise, the result is the LOOP_STMT. */
3069 {
3073 }
3074 else
3080 }
3081 \f
3082 /* This page implements a form of Named Return Value optimization modelled
3083 on the C++ optimization of the same name. The main difference is that
3084 we disregard any semantical considerations when applying it here, the
3085 counterpart being that we don't try to apply it to semantically loaded
3086 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3088 We consider a function body of the following GENERIC form:
3090 return_type R1;
3091 [...]
3092 RETURN_EXPR [<retval> = ...]
3093 [...]
3094 RETURN_EXPR [<retval> = R1]
3095 [...]
3096 return_type Ri;
3097 [...]
3098 RETURN_EXPR [<retval> = ...]
3099 [...]
3100 RETURN_EXPR [<retval> = Ri]
3101 [...]
3103 and we try to fulfill a simple criterion that would make it possible to
3104 replace one or several Ri variables with the RESULT_DECL of the function.
3106 The first observation is that RETURN_EXPRs that don't directly reference
3107 any of the Ri variables on the RHS of their assignment are transparent wrt
3108 the optimization. This is because the Ri variables aren't addressable so
3109 any transformation applied to them doesn't affect the RHS; moreover, the
3110 assignment writes the full <retval> object so existing values are entirely
3111 discarded.
3113 This property can be extended to some forms of RETURN_EXPRs that reference
3114 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3115 case, in particular when function calls are involved.
3117 Therefore the algorithm is as follows:
3119 1. Collect the list of candidates for a Named Return Value (Ri variables
3120 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3121 other expressions on the RHS of such assignments.
3123 2. Prune the members of the first list (candidates) that are referenced
3124 by a member of the second list (expressions).
3126 3. Extract a set of candidates with non-overlapping live ranges from the
3127 first list. These are the Named Return Values.
3129 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3130 Named Return Values in the function with the RESULT_DECL.
3132 If the function returns an unconstrained type, things are a bit different
3133 because the anonymous return object is allocated on the secondary stack
3134 and RESULT_DECL is only a pointer to it. Each return object can be of a
3135 different size and is allocated separately so we need not care about the
3136 aforementioned overlapping issues. Therefore, we don't collect the other
3137 expressions and skip step #2 in the algorithm. */
3139 struct nrv_data
3140 {
3141 bitmap nrv;
3142 tree result;
3143 Node_Id gnat_ret;
3145 };
3147 /* Return true if T is a Named Return Value. */
3151 {
3153 }
3155 /* Helper function for walk_tree, used by finalize_nrv below. */
3157 static tree
3159 {
3163 /* No need to walk into types or decls. */
3171 }
3173 /* Prune Named Return Values in BLOCK and return true if there is still a
3174 Named Return Value in BLOCK or one of its sub-blocks. */
3176 static bool
3178 {
3180 tree t;
3182 /* First recurse on the sub-blocks. */
3186 /* Then make sure to keep at most one NRV per block. */
3189 {
3192 else
3194 }
3197 }
3199 /* Helper function for walk_tree, used by finalize_nrv below. */
3201 static tree
3203 {
3207 /* No need to walk into types. */
3211 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3212 nop, but differs from using NULL_TREE in that it indicates that we care
3213 about the value of the RESULT_DECL. */
3216 {
3219 /* If this is the temporary created for a return value with variable
3220 size in Call_to_gnu, we replace the RHS with the init expression. */
3225 {
3228 }
3229 else
3232 /* Strip useless conversions around the return value. */
3237 {
3240 else
3242 }
3243 }
3245 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3246 if needed. */
3249 {
3253 {
3258 }
3259 else
3263 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3266 /* ??? Kludge to avoid an assertion failure during inlining. */
3269 }
3271 /* And replace all uses of NRVs with the RESULT_DECL. */
3275 /* Avoid walking into the same tree more than once. Unfortunately, we
3276 can't just use walk_tree_without_duplicates because it would only
3277 call us for the first occurrence of NRVs in the function body. */
3282 }
3284 /* Likewise, but used when the function returns an unconstrained type. */
3286 static tree
3288 {
3292 /* No need to walk into types. */
3296 /* We need to see the DECL_EXPR of NRVs before any other references so we
3297 walk the body of BIND_EXPR before walking its variables. */
3301 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3302 return value built by the allocator instead of the whole construct. */
3305 {
3308 /* This is the construct returned by the allocator. */
3311 {
3313 ret_val
3316 else
3318 }
3320 /* Strip useless conversions around the return value. */
3325 /* Strip unpadding around the return value. */
3330 /* Assign the new return value to the RESULT_DECL. */
3334 }
3336 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3337 into a new variable. */
3340 {
3347 /* Create an artificial context to build the allocation. */
3352 /* This will return a COMPOUND_EXPR with the allocation in the first
3353 arm and the final return value in the second arm. */
3360 /* The new variable is built as a reference to the allocated space. */
3361 new_var
3367 {
3368 /* The new initial value is a COMPOUND_EXPR with the allocation in
3369 the first arm and the value of P_ARRAY in the second arm. */
3375 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3383 }
3384 else
3385 {
3386 /* The new initial value is just the allocation. */
3389 }
3393 /* Destroy the artificial context and insert the new statements. */
3398 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3403 /* Save the new return value and the dereference of NEW_VAR. */
3407 /* ??? Kludge to avoid messing up during inlining. */
3409 }
3411 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3415 /* Avoid walking into the same tree more than once. Unfortunately, we
3416 can't just use walk_tree_without_duplicates because it would only
3417 call us for the first occurrence of NRVs in the function body. */
3422 }
3424 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3425 contains the candidates for Named Return Value and OTHER is a list of
3426 the other return values. GNAT_RET is a representative return node. */
3428 static void
3430 {
3433 walk_tree_fn func;
3435 tree iter;
3437 /* We shouldn't be applying the optimization to return types that we aren't
3438 allowed to manipulate freely. */
3441 /* Prune the candidates that are referenced by other return values. */
3450 /* Prune also the candidates that are referenced by nested functions. */
3458 /* Extract a set of NRVs with non-overlapping live ranges. */
3462 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3469 else
3473 }
3475 /* Return true if RET_VAL can be used as a Named Return Value for the
3476 anonymous return object RET_OBJ. */
3478 static bool
3480 {
3500 }
3502 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3503 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3504 around RESULT_OBJ, which may be null in this case. */
3506 static tree
3508 {
3509 tree result_expr;
3512 {
3513 /* The gimplifier explicitly enforces the following invariant:
3515 RETURN_EXPR
3516 |
3517 INIT_EXPR
3518 / \
3519 / \
3520 RET_OBJ ...
3522 As a consequence, type consistency dictates that we use the type
3523 of the RET_OBJ as the operation type. */
3526 /* Convert the right operand to the operation type. Note that this is
3527 the transformation applied in the INIT_EXPR case of build_binary_op,
3528 with the assumption that the type cannot involve a placeholder. */
3532 /* We always can use an INIT_EXPR for the return object. */
3535 /* If the function returns an aggregate type, find out whether this is
3536 a candidate for Named Return Value. If so, record it. Otherwise,
3537 if this is an expression of some kind, record it elsewhere. */
3543 {
3544 /* Recognize the temporary created for a return value with variable
3545 size in Call_to_gnu. We want to eliminate it if possible. */
3552 /* Strip useless conversions around the return value. */
3556 /* Now apply the test to the return value. */
3558 {
3562 }
3564 /* Note that we need not care about CONSTRUCTORs here, as they are
3565 totally transparent given the read-compose-write semantics of
3566 assignments from CONSTRUCTORs. */
3569 }
3570 }
3571 else
3575 }
3576 \f
3577 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3578 don't return anything. */
3580 static void
3582 {
3583 /* Defining identifier of a parameter to the subprogram. */
3584 Entity_Id gnat_param;
3585 /* The defining identifier for the subprogram body. Note that if a
3586 specification has appeared before for this body, then the identifier
3587 occurring in that specification will also be a defining identifier and all
3588 the calls to this subprogram will point to that specification. */
3589 Entity_Id gnat_subprog_id
3592 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3593 tree gnu_subprog_decl;
3594 /* Its RESULT_DECL node. */
3595 tree gnu_result_decl;
3596 /* Its FUNCTION_TYPE node. */
3597 tree gnu_subprog_type;
3598 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3599 tree gnu_cico_list;
3600 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3602 tree gnu_result;
3603 location_t locus;
3607 /* If this is a generic object or if it has been eliminated,
3608 ignore it. */
3614 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3615 the already-elaborated tree node. However, if this subprogram had its
3616 elaboration deferred, we will already have made a tree node for it. So
3617 treat it as not being defined in that case. Such a subprogram cannot
3618 have an address clause or a freeze node, so this test is safe, though it
3619 does disable some otherwise-useful error checking. */
3620 gnu_subprog_decl
3630 /* If the function returns by invisible reference, make it explicit in the
3631 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3633 {
3637 }
3639 /* Set the line number in the decl to correspond to that of the body. */
3643 /* Initialize the information structure for the function. */
3652 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3653 properly copied out by the return statement. We do this by making a new
3654 block and converting any return into a goto to a label at the end of the
3655 block. */
3657 {
3666 /* If this is a function with copy-in/copy-out parameters and which does
3667 not return by invisible reference, we also need a variable for the
3668 return value to be placed. */
3670 {
3671 tree gnu_return_type
3674 gnu_return_var
3679 }
3683 /* See whether there are parameters for which we don't have a GCC tree
3684 yet. These must be Out parameters. Make a VAR_DECL for them and
3685 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3686 We can match up the entries because TYPE_CI_CO_LIST is in the order
3687 of the parameters. */
3692 {
3694 tree gnu_decl;
3696 /* Skip any entries that have been already filled in; they must
3697 correspond to In Out parameters. */
3701 /* Do any needed dereferences for by-ref objects. */
3707 /* Do any needed references for padded types. */
3710 }
3711 }
3712 else
3715 /* Get a tree corresponding to the code for the subprogram. */
3721 /* Generate the code of the subprogram itself. A return statement will be
3722 present and any Out parameters will be handled there. */
3727 /* If we populated the parameter attributes cache, we need to make sure that
3728 the cached expressions are evaluated on all the possible paths leading to
3729 their uses. So we force their evaluation on entry of the function. */
3732 {
3739 {
3746 }
3752 }
3754 /* If we are dealing with a return from an Ada procedure with parameters
3755 passed by copy-in/copy-out, we need to return a record containing the
3756 final values of these parameters. If the list contains only one entry,
3757 return just that entry though.
3759 For a full description of the copy-in/copy-out parameter mechanism, see
3760 the part of the gnat_to_gnu_entity routine dealing with the translation
3761 of subprograms.
3763 We need to make a block that contains the definition of that label and
3764 the copying of the return value. It first contains the function, then
3765 the label and copy statement. */
3767 {
3768 const Node_Id gnat_end_label
3777 /* If this is a function which returns by invisible reference, the
3778 return value has already been dealt with at the return statements,
3779 so we only need to indirectly copy out the parameters. */
3781 {
3782 tree gnu_ret_deref
3784 tree t;
3789 {
3790 tree gnu_field_deref
3796 }
3797 }
3799 /* Otherwise, if this is a procedure or a function which does not return
3800 by invisible reference, we can do a direct block-copy out. */
3801 else
3802 {
3803 tree gnu_retval;
3807 else
3808 gnu_retval
3810 gnu_cico_list);
3814 }
3818 }
3822 /* Attempt setting the end_locus of our GCC body tree, typically a
3823 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3824 declaration tree. */
3828 /* On SEH targets, install an exception handler around the main entry
3829 point to catch unhandled exceptions. */
3832 {
3833 tree t;
3834 tree etype;
3846 }
3850 /* Finally annotate the parameters and disconnect the trees for parameters
3851 that we have turned into variables since they are now unusable. */
3855 {
3864 }
3866 /* Disconnect the variable created for the return value. */
3870 /* If the function returns an aggregate type and we have candidates for
3871 a Named Return Value, finalize the optimization. */
3873 {
3880 }
3882 /* If this is an inlined external function that has been marked uninlinable,
3883 drop the body and stop there. Otherwise compile the body. */
3886 else
3888 }
3889 \f
3890 /* Return true if GNAT_NODE requires atomic synchronization. */
3892 static bool
3894 {
3896 Node_Kind kind;
3899 /* First, scan the node to find the Atomic_Sync_Required flag. */
3902 {
3905 }
3908 {
3920 }
3922 /* Then, scan the parent to find out cases where the flag is irrelevant. */
3925 {
3928 /* Do not mess up machine code insertions. */
3934 /* Do not generate a function call as a renamed object. */
3939 }
3942 }
3943 \f
3944 /* Create a temporary variable with PREFIX and TYPE, and return it. */
3946 static tree
3948 {
3956 }
3958 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
3959 Put the initialization statement into GNU_INIT_STMT and annotate it with
3960 the SLOC of GNAT_NODE. Return the temporary variable. */
3962 static tree
3964 Node_Id gnat_node)
3965 {
3972 }
3974 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
3975 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
3976 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
3977 If GNU_TARGET is non-null, this must be a function call on the RHS of a
3978 N_Assignment_Statement and the result is to be placed into that object.
3979 If, in addition, ATOMIC_SYNC is true, then the assignment to GNU_TARGET
3980 requires atomic synchronization. */
3982 static tree
3985 {
3988 /* The GCC node corresponding to the GNAT subprogram name. This can either
3989 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
3990 or an indirect reference expression (an INDIRECT_REF node) pointing to a
3991 subprogram. */
3993 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
3995 /* The return type of the FUNCTION_TYPE. */
4006 Entity_Id gnat_formal;
4007 Node_Id gnat_actual;
4011 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4012 all our args first. */
4014 {
4024 {
4027 }
4030 }
4032 /* For a call to a nested function, check the inlining status. */
4037 /* The only way we can be making a call via an access type is if Name is an
4038 explicit dereference. In that case, get the list of formal args from the
4039 type the access type is pointing to. Otherwise, get the formals from the
4040 entity being called. */
4044 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4046 else
4049 /* The lifetime of the temporaries created for the call ends right after the
4050 return value is copied, so we can give them the scope of the elaboration
4051 routine at top level. */
4053 {
4056 }
4058 /* First, create the temporary for the return value when:
4060 1. There is no target and the function has copy-in/copy-out parameters,
4061 because we need to preserve the return value before copying back the
4062 parameters.
4064 2. There is no target and this is not an object declaration, and the
4065 return type has variable size, because in these cases the gimplifier
4066 cannot create the temporary.
4068 3. There is a target and it is a slice or an array with fixed size,
4069 and the return type has variable size, because the gimplifier
4070 doesn't handle these cases.
4072 This must be done before we push a binding level around the call, since
4073 we will pop it before copying the return value. */
4076 || (!gnu_target
4079 || (gnu_target
4087 /* Create the list of the actual parameters as GCC expects it, namely a
4088 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4089 is an expression and the TREE_PURPOSE field is null. But skip Out
4090 parameters not passed by reference and that need not be copied in. */
4095 {
4100 const bool is_true_formal_parm
4102 const bool is_by_ref_formal_parm
4103 = is_true_formal_parm
4106 /* In the Out or In Out case, we must suppress conversions that yield
4107 an lvalue but can nevertheless cause the creation of a temporary,
4108 because we need the real object in this case, either to pass its
4109 address if it's passed by reference or as target of the back copy
4110 done after the call if it uses the copy-in/copy-out mechanism.
4111 We do it in the In case too, except for an unchecked conversion
4112 to an elementary type or a constrained composite type because it
4113 alone can cause the actual to be misaligned and the addressability
4114 test is applied to the real object. */
4115 const bool suppress_type_conversion
4122 Node_Id gnat_name = suppress_type_conversion
4125 tree gnu_actual;
4127 /* If it's possible we may need to use this expression twice, make sure
4128 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4129 to force side-effects before the call.
4130 ??? This is more conservative than we need since we don't need to do
4131 this for pass-by-ref with no conversion. */
4135 /* If we are passing a non-addressable parameter by reference, pass the
4136 address of a copy. In the Out or In Out case, set up to copy back
4137 out after the call. */
4141 {
4145 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4146 but sort of an instantiation for them. */
4148 ;
4150 /* If the type is passed by reference, a copy is not allowed. */
4153 gnat_actual);
4155 /* For users of Starlet we issue a warning because the interface
4156 apparently assumes that by-ref parameters outlive the procedure
4157 invocation. The code still will not work as intended, but we
4158 cannot do much better since low-level parts of the back-end
4159 would allocate temporaries at will because of the misalignment
4160 if we did not do so here. */
4162 {
4163 post_error
4165 post_error_ne
4169 gnat_formal);
4170 }
4172 /* If the actual type of the object is already the nominal type,
4173 we have nothing to do, except if the size is self-referential
4174 in which case we'll remove the unpadding below. */
4177 ;
4179 /* Otherwise remove the unpadding from all the objects. */
4181 && TYPE_IS_PADDING_P
4185 /* Otherwise convert to the nominal type of the object if needed.
4186 There are several cases in which we need to make the temporary
4187 using this type instead of the actual type of the object when
4188 they are distinct, because the expectations of the callee would
4189 otherwise not be met:
4190 - if it's a justified modular type,
4191 - if the actual type is a smaller form of it,
4192 - if it's a smaller form of the actual type. */
4196 gnu_name_type)))
4202 /* If this is an In Out or Out parameter and we're returning a value,
4203 we need to create a temporary for the return value because we must
4204 preserve it before copying back at the very end. */
4208 /* If we haven't pushed a binding level, push a new one. This will
4209 narrow the lifetime of the temporary we are about to make as much
4210 as possible. The drawback is that we'd need to create a temporary
4211 for the return value, if any (see comment before the loop). So do
4212 it only when this temporary was already created just above. */
4214 {
4218 }
4220 /* Create an explicit temporary holding the copy. */
4221 gnu_temp
4224 /* But initialize it on the fly like for an implicit temporary as
4225 we aren't necessarily having a statement list. */
4227 gnu_temp);
4229 /* Set up to move the copy back to the original if needed. */
4231 {
4232 /* If the original is a COND_EXPR whose first arm isn't meant to
4233 be further used, just deal with the second arm. This is very
4234 likely the conditional expression built for a check. */
4237 && integer_zerop
4241 gnu_stmt
4246 }
4247 }
4249 /* Start from the real object and build the actual. */
4252 /* If this is an atomic access of an In or In Out parameter for which
4253 synchronization is required, build the atomic load. */
4255 && !is_by_ref_formal_parm
4260 /* If this was a procedure call, we may not have removed any padding.
4261 So do it here for the part we will use as an input, if any. */
4264 gnu_actual
4267 /* Put back the conversion we suppressed above in the computation of the
4268 real object. And even if we didn't suppress any conversion there, we
4269 may have suppressed a conversion to the Etype of the actual earlier,
4270 since the parent is a procedure call, so put it back here. */
4273 gnu_actual
4276 else
4277 gnu_actual
4280 /* Make sure that the actual is in range of the formal's type. */
4283 gnu_actual
4286 /* Unless this is an In parameter, we must remove any justified modular
4287 building from GNU_NAME to get an lvalue. */
4292 gnu_name
4295 /* First see if the parameter is passed by reference. */
4297 {
4299 {
4300 /* In Out or Out parameters passed by reference don't use the
4301 copy-in/copy-out mechanism so the address of the real object
4302 must be passed to the function. */
4305 /* If we have a padded type, be sure we've removed padding. */
4308 gnu_actual);
4310 /* If we have the constructed subtype of an aliased object
4311 with an unconstrained nominal subtype, the type of the
4312 actual includes the template, although it is formally
4313 constrained. So we need to convert it back to the real
4314 constructed subtype to retrieve the constrained part
4315 and takes its address. */
4321 gnu_actual);
4322 }
4324 /* There is no need to convert the actual to the formal's type before
4325 taking its address. The only exception is for unconstrained array
4326 types because of the way we build fat pointers. */
4328 {
4329 /* Put back a view conversion for In Out or Out parameters. */
4332 gnu_actual);
4334 }
4336 /* The symmetry of the paths to the type of an entity is broken here
4337 since arguments don't know that they will be passed by ref. */
4340 }
4342 /* Then see if the parameter is an array passed to a foreign convention
4343 subprogram. */
4345 {
4351 {
4354 }
4356 /* Take the address of the object and convert to the proper pointer
4357 type. We'd like to actually compute the address of the beginning
4358 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4359 possibility that the ARRAY_REF might return a constant and we'd be
4360 getting the wrong address. Neither approach is exactly correct,
4361 but this is the most likely to work in all cases. */
4363 }
4365 /* Otherwise the parameter is passed by copy. */
4366 else
4367 {
4368 tree gnu_size;
4373 /* If we didn't create a PARM_DECL for the formal, this means that
4374 it is an Out parameter not passed by reference and that need not
4375 be copied in. In this case, the value of the actual need not be
4376 read. However, we still need to make sure that its side-effects
4377 are evaluated before the call, so we evaluate its address. */
4379 {
4381 {
4384 }
4386 }
4390 /* If this is 'Null_Parameter, pass a zero even though we are
4391 dereferencing it. */
4397 gnu_actual
4401 integer_zero_node),
4403 else
4405 }
4408 }
4410 gnu_call
4414 /* If we have created a temporary for the return value, initialize it. */
4416 {
4417 tree gnu_stmt
4422 }
4424 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4425 unpack the valued returned from the function into the In Out or Out
4426 parameters. We deal with the function return (if this is an Ada
4427 function) below. */
4429 {
4430 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4431 copy-out parameters. */
4435 /* The call sequence must contain one and only one call, even though the
4436 function is pure. Save the result into a temporary if needed. */
4438 {
4440 {
4441 tree gnu_stmt;
4442 /* If we haven't pushed a binding level, push a new one. This
4443 will narrow the lifetime of the temporary we are about to
4444 make as much as possible. */
4446 {
4450 }
4451 gnu_call
4454 }
4457 }
4459 /* The first entry is for the actual return value if this is a
4460 function, so skip it. */
4466 else
4473 /* If we are dealing with a copy-in/copy-out parameter, we must
4474 retrieve its value from the record returned in the call. */
4480 {
4481 /* Get the value to assign to this Out or In Out parameter. It is
4482 either the result of the function if there is only a single such
4483 parameter or the appropriate field from the record returned. */
4484 tree gnu_result
4486 ? gnu_call
4490 /* If the actual is a conversion, get the inner expression, which
4491 will be the real destination, and convert the result to the
4492 type of the actual parameter. */
4493 tree gnu_actual
4496 /* If the result is a padded type, remove the padding. */
4498 gnu_result
4500 gnu_result);
4502 /* If the actual is a type conversion, the real target object is
4503 denoted by the inner Expression and we need to convert the
4504 result to the associated type.
4505 We also need to convert our gnu assignment target to this type
4506 if the corresponding GNU_NAME was constructed from the GNAT
4507 conversion node and not from the inner Expression. */
4509 {
4510 gnu_result
4511 = convert_with_check
4519 }
4521 /* Unchecked conversions as actuals for Out parameters are not
4522 allowed in user code because they are not variables, but do
4523 occur in front-end expansions. The associated GNU_NAME is
4524 always obtained from the inner expression in such cases. */
4527 gnu_result,
4529 else
4530 {
4532 gnu_result
4534 gnat_actual);
4539 }
4543 else
4550 }
4551 }
4553 /* If this is a function call, the result is the call expression unless a
4554 target is specified, in which case we copy the result into the target
4555 and return the assignment statement. */
4557 {
4558 /* If this is a function with copy-in/copy-out parameters, extract the
4559 return value from it and update the return type. */
4561 {
4566 }
4568 /* If the function returns an unconstrained array or by direct reference,
4569 we have to dereference the pointer. */
4575 {
4579 /* If range check is needed, emit code to generate it. */
4581 gnu_call
4583 gnat_parent);
4585 /* ??? If the return type has variable size, then force the return
4586 slot optimization as we would not be able to create a temporary.
4587 Likewise if it was unconstrained as we would copy too much data.
4588 That's what has been done historically. */
4591 && CONTAINS_PLACEHOLDER_P
4594 else
4599 else
4600 gnu_call
4604 }
4605 else
4607 }
4609 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4610 parameters, the result is just the call statement. */
4614 /* Finally, add the copy back statements, if any. */
4620 /* If we have pushed a binding level, pop it and finish up the enclosing
4621 statement group. */
4623 {
4627 }
4629 /* Otherwise, retrieve the statement list, if any. */
4633 /* Otherwise, just return the call expression. */
4634 else
4637 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4638 But first simplify if we have only one statement in the list. */
4640 {
4644 gnu_result
4646 }
4649 }
4650 \f
4651 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4652 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4654 static tree
4656 {
4659 /* If just annotating, ignore all EH and cleanups. */
4663 bool setjmp_longjmp
4669 tree gnu_result;
4670 tree gnu_expr;
4671 Node_Id gnat_temp;
4672 /* Node providing the sloc for the cleanup actions. */
4675 gnat_node);
4677 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4678 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4679 add_cleanup, and when we leave the binding, end_stmt_group will create
4680 the TRY_FINALLY_EXPR.
4682 ??? The region level calls down there have been specifically put in place
4683 for a ZCX context and currently the order in which things are emitted
4684 (region/handlers) is different from the SJLJ case. Instead of putting
4685 other calls with different conditions at other places for the SJLJ case,
4686 it seems cleaner to reorder things for the SJLJ case and generalize the
4687 condition to make it not ZCX specific.
4689 If there are any exceptions or cleanup processing involved, we need an
4690 outer statement group (for Setjmp_Longjmp) and binding level. */
4692 {
4695 }
4697 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
4698 area for address of previous buffer. Do this first since we need to have
4699 the setjmp buf known for any decls in this block. */
4701 {
4702 gnu_jmpsave_decl
4704 jmpbuf_ptr_type,
4709 /* The __builtin_setjmp receivers will immediately reinstall it. Now
4710 because of the unstructured form of EH used by setjmp_longjmp, there
4711 might be forward edges going to __builtin_setjmp receivers on which
4712 it is uninitialized, although they will never be actually taken. */
4714 gnu_jmpbuf_decl
4716 jmpbuf_type,
4717 NULL_TREE,
4723 /* When we exit this block, restore the saved value. */
4725 gnat_cleanup_loc_node);
4726 }
4728 /* If we are to call a function when exiting this block, add a cleanup
4729 to the binding level we made above. Note that add_cleanup is FIFO
4730 so we must register this cleanup after the EH cleanup just above. */
4733 gnat_cleanup_loc_node);
4735 /* Now build the tree for the declarations and statements inside this block.
4736 If this is SJLJ, set our jmp_buf as the current buffer. */
4740 {
4743 gnu_jmpbuf_decl));
4746 }
4752 /* Generate code for each statement in the block. */
4760 /* Now generate code for the two exception models, if either is relevant for
4761 this block. */
4763 {
4765 tree gnu_handler;
4767 /* Make a binding level for the exception handling declarations and code
4768 and set up gnu_except_ptr_stack for the handlers to use. */
4779 /* Generate code for each handler. The N_Exception_Handler case does the
4780 real work and returns a COND_EXPR for each handler, which we chain
4781 together here. */
4784 {
4787 /* If this is the first one, set it as the outer one. Otherwise,
4788 point the "else" part of the previous handler to us. Then point
4789 to our "else" part. */
4792 else
4796 }
4798 /* If none of the exception handlers did anything, re-raise but do not
4799 defer abortion. */
4802 set_expr_location_from_node
4808 else
4811 /* End the binding level dedicated to the exception handlers and get the
4812 whole statement group. */
4817 /* If the setjmp returns 1, we restore our incoming longjmp value and
4818 then check the handlers. */
4821 gnu_jmpsave_decl),
4822 gnat_node);
4826 /* This block is now "if (setjmp) ... <handlers> else <block>". */
4828 (build_call_n_expr
4831 gnu_jmpbuf_decl))),
4833 }
4835 {
4836 tree gnu_handlers;
4837 location_t locus;
4839 /* First make a block containing the handlers. */
4847 /* Now make the TRY_CATCH_EXPR for the block. */
4850 /* Set a location. We need to find a unique location for the dispatching
4851 code, otherwise we can get coverage or debugging issues. Try with
4852 the location of the end label. */
4856 else
4857 /* Clear column information so that the exception handler of an
4858 implicit transient block does not incorrectly inherit the slocs
4859 of a decision, which would otherwise confuse control flow based
4860 coverage analysis tools. */
4862 }
4863 else
4866 /* Now close our outer block, if we had to make one. */
4868 {
4872 }
4875 }
4876 \f
4877 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4878 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
4879 exception handling. */
4881 static tree
4883 {
4884 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
4885 an "if" statement to select the proper exceptions. For "Others", exclude
4886 exceptions where Handled_By_Others is nonzero unless the All_Others flag
4887 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
4890 Node_Id gnat_temp;
4894 {
4895 tree this_choice;
4898 {
4901 else
4902 this_choice
4903 = build_binary_op
4905 convert
4907 build_component_ref
4908 (build_unary_op
4913 integer_zero_node);
4914 }
4918 {
4920 tree gnu_expr;
4922 /* Exception may be a renaming. Recover original exception which is
4923 the one elaborated and registered. */
4929 this_choice
4930 = build_binary_op
4935 }
4936 else
4941 }
4944 }
4945 \f
4946 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
4947 to a GCC tree, which is returned. This is the variant for ZCX. */
4949 static tree
4951 {
4954 Node_Id gnat_temp;
4956 /* We build a TREE_LIST of nodes representing what exception types this
4957 handler can catch, with special cases for others and all others cases.
4959 Each exception type is actually identified by a pointer to the exception
4960 id, or to a dummy object for "others" and "all others". */
4963 {
4967 {
4970 }
4973 {
4976 /* Exception may be a renaming. Recover original exception which is
4977 the one elaborated and registered. */
4983 }
4984 else
4987 /* The GCC interface expects NULL to be passed for catch all handlers, so
4988 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
4989 is integer_zero_node. It would not work, however, because GCC's
4990 notion of "catch all" is stronger than our notion of "others". Until
4991 we correctly use the cleanup interface as well, doing that would
4992 prevent the "all others" handlers from being seen, because nothing
4993 can be caught beyond a catch all from GCC's point of view. */
4995 }
5000 /* Expand a call to the begin_handler hook at the beginning of the handler,
5001 and arrange for a call to the end_handler hook to occur on every possible
5002 exit path.
5004 The hooks expect a pointer to the low level occurrence. This is required
5005 for our stack management scheme because a raise inside the handler pushes
5006 a new occurrence on top of the stack, which means that this top does not
5007 necessarily match the occurrence this handler was dealing with.
5009 __builtin_eh_pointer references the exception occurrence being
5010 propagated. Upon handler entry, this is the exception for which the
5011 handler is triggered. This might not be the case upon handler exit,
5012 however, as we might have a new occurrence propagated by the handler's
5013 body, and the end_handler hook called as a cleanup in this context.
5015 We use a local variable to retrieve the incoming value at handler entry
5016 time, and reuse it to feed the end_handler hook's argument at exit. */
5018 gnu_current_exc_ptr
5028 gnu_incoming_exc_ptr),
5029 gnat_node);
5031 /* Declare and initialize the choice parameter, if present. */
5033 {
5034 tree gnu_param
5040 gnu_incoming_exc_ptr));
5041 }
5043 /* We don't have an End_Label at hand to set the location of the cleanup
5044 actions, so we use that of the exception handler itself instead. */
5046 gnat_node);
5052 return
5054 }
5055 \f
5056 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5058 static void
5060 {
5065 Entity_Id gnat_entity;
5066 Node_Id gnat_pragma;
5067 /* Make the decl for the elaboration procedure. */
5068 tree gnu_elab_proc_decl
5069 = create_subprog_decl
5072 gnat_unit);
5078 /* Initialize the information structure for the function. */
5087 /* For a body, first process the spec if there is one. */
5093 {
5100 }
5102 /* Then process any pragmas and declarations preceding the unit. */
5111 /* Process the unit itself. */
5114 /* Generate code for all the inlined subprograms. */
5118 {
5119 Node_Id gnat_body;
5121 /* Without optimization, process only the required subprograms. */
5127 {
5128 /* ??? This happens when only the spec of a package is provided. */
5132 gnat_body
5134 }
5136 /* Define the entity first so we set DECL_EXTERNAL. */
5139 }
5141 /* Process any pragmas and actions following the unit. */
5146 /* Save away what we've made so far and record this potential elaboration
5147 procedure. */
5160 /* Generate elaboration code for this unit, if necessary, and say whether
5161 we did or not. */
5164 /* Invalidate the global renaming pointers. This is necessary because
5165 stabilization of the renamed entities may create SAVE_EXPRs which
5166 have been tied to a specific elaboration routine just above. */
5169 /* Force the processing for all nodes that remain in the queue. */
5171 }
5172 \f
5173 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5174 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5175 we should place the result type. LABEL_P is true if there is a label to
5176 branch to for the exception. */
5178 static tree
5180 {
5184 const bool with_extra_info
5185 = Exception_Extra_Info
5193 {
5203 {
5209 {
5229 }
5236 && gnu_low_bound
5237 && gnu_high_bound
5240 gnu_result
5244 /* If loop unswitching is enabled, we try to compute invariant
5245 conditions for checks applied to iteration variables, i.e.
5246 conditions that are both independent of the variable and
5247 necessary in order for the check to fail in the course of
5248 some iteration, and prepend them to the original condition
5249 of the checks. This will make it possible later for the
5250 loop unswitching pass to replace the loop with two loops,
5251 one of which has the checks eliminated and the other has
5252 the original checks reinstated, and a run time selection.
5253 The former loop will be suitable for vectorization. */
5256 && (!gnu_low_bound
5258 && (!gnu_high_bound
5261 {
5266 boolean_true_node);
5268 boolean_type_node,
5271 }
5272 }
5277 }
5279 common:
5284 /* If the type is VOID, this is a statement, so we need to generate the code
5285 for the call. Handle a condition, if there is one. */
5287 {
5289 {
5294 }
5295 }
5296 else
5300 }
5301 \f
5302 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5303 parameter of a call. */
5305 static bool
5307 {
5322 }
5324 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5325 of an assignment or an actual parameter of a call. */
5327 static bool
5329 {
5330 Node_Kind kind;
5342 }
5344 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5345 as gigi is concerned. This is used to avoid conversions on the LHS. */
5347 static bool
5349 {
5352 /* The conversion must be on the LHS of an assignment or an actual parameter
5353 of a call. Otherwise, even if the conversion was essentially a no-op, it
5354 could de facto ensure type consistency and this should be preserved. */
5360 /* We're interested in artificial conversions generated by the front-end
5361 to make private types explicit, e.g. in Expand_Assign_Array. */
5368 /* The direct conversion to the underlying type is a no-op. */
5372 /* For an array subtype, the conversion to the PAIT is a no-op. */
5377 /* For a record subtype, the conversion to the type is a no-op. */
5383 }
5385 /* This function is the driver of the GNAT to GCC tree transformation process.
5386 It is the entry point of the tree transformer. GNAT_NODE is the root of
5387 some GNAT tree. Return the root of the corresponding GCC tree. If this
5388 is an expression, return the GCC equivalent of the expression. If this
5389 is a statement, return the statement or add it to the current statement
5390 group, in which case anything returned is to be interpreted as occurring
5391 after anything added. */
5393 tree
5395 {
5401 Node_Id gnat_temp;
5403 /* Save node number for error message and set location information. */
5407 /* If this node is a statement and we are only annotating types, return an
5408 empty statement list. */
5412 /* If this node is a non-static subexpression and we are only annotating
5413 types, make this into a NULL_EXPR. */
5420 N_Raise_Constraint_Error));
5429 {
5432 /* If this is a statement and we are at top level, it must be part of
5433 the elaboration procedure, so mark us as being in that procedure. */
5435 {
5438 }
5440 /* If we are in the elaboration procedure, check if we are violating a
5441 No_Elaboration_Code restriction by having a statement there. Don't
5442 check for a possible No_Elaboration_Code restriction violation on
5443 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5444 every nested real statement instead. This also avoids triggering
5445 spurious errors on dummy (empty) sequences created by the front-end
5446 for package bodies in some cases. */
5450 }
5453 {
5454 /********************************/
5455 /* Chapter 2: Lexical Elements */
5456 /********************************/
5464 /* If this is an atomic access on the RHS for which synchronization is
5465 required, build the atomic load. */
5472 {
5473 tree gnu_type;
5475 /* Get the type of the result, looking inside any padding and
5476 justified modular types. Then get the value in that type. */
5485 /* If the result overflows (meaning it doesn't fit in its base type),
5486 abort. We would like to check that the value is within the range
5487 of the subtype, but that causes problems with subtypes whose usage
5488 will raise Constraint_Error and with biased representation, so
5489 we don't. */
5491 }
5495 /* If a Entity is present, it means that this was one of the
5496 literals in a user-defined character type. In that case,
5497 just return the value in the CONST_DECL. Otherwise, use the
5498 character code. In that case, the base type should be an
5499 INTEGER_TYPE, but we won't bother checking for that. */
5503 else
5504 gnu_result
5505 = build_int_cst_type
5512 /* If this is of a fixed-point type, the value we want is the value of
5513 the corresponding integer. */
5515 {
5517 gnu_result_type);
5519 }
5521 else
5522 {
5525 /* First convert the value to a machine number if it isn't already.
5526 That will force the base to 2 for non-zero values and simplify
5527 the rest of the logic. */
5529 ur_realval
5535 else
5536 {
5537 REAL_VALUE_TYPE tmp;
5541 /* The base must be 2 as Machine guarantees this, so we scale
5542 the value, which we know can fit in the mantissa of the type
5543 (hence the use of that type above). */
5548 }
5550 /* Now see if we need to negate the result. Do it this way to
5551 properly handle -0. */
5553 gnu_result
5555 gnu_result);
5556 }
5563 {
5570 else
5573 /* Build the string with the characters in the literal. Note
5574 that Ada strings are 1-origin. */
5578 /* Put a null at the end of the string in case it's in a context
5579 where GCC will want to treat it as a C string. */
5584 /* Strings in GCC don't normally have types, but we want
5585 this to not be converted to the array type. */
5590 }
5591 else
5592 {
5593 /* Build a list consisting of each character, then make
5594 the aggregate. */
5604 {
5610 }
5613 }
5620 /**************************************/
5621 /* Chapter 3: Declarations and Types */
5622 /**************************************/
5639 /* If we are just annotating types and this object has an unconstrained
5640 or task type, don't elaborate it. */
5650 && (!type_annotate_only
5652 {
5655 gnu_expr
5658 /* If this object has its elaboration delayed, we must force
5659 evaluation of GNU_EXPR right now and save it for when the object
5660 is frozen. */
5662 {
5664 ;
5666 gnu_expr
5671 else
5675 }
5676 }
5677 else
5683 /* If this is a deferred constant with an address clause, we ignore the
5684 full view since the clause is on the partial view and we cannot have
5685 2 different GCC trees for the object. The only bits of the full view
5686 we will use is the initializer, but it will be directly fetched. */
5699 /* Don't do anything if this renaming is handled by the front end or if
5700 we are just annotating types and this object has a composite or task
5701 type, don't elaborate it. We return the result in case it has any
5702 SAVE_EXPRs in it that need to be evaluated here. */
5704 && ! (type_annotate_only
5708 gnu_result
5711 else
5718 gnu_result
5721 else
5733 /* These are fully handled in the front end. */
5734 /* ??? For package renamings, find a way to use GENERIC namespaces so
5735 that we get proper debug information for them. */
5739 /*************************************/
5740 /* Chapter 4: Names and Expressions */
5741 /*************************************/
5748 /* If this is an atomic access on the RHS for which synchronization is
5749 required, build the atomic load. */
5756 {
5758 tree gnu_type;
5765 /* Convert vector inputs to their representative array type, to fit
5766 what the code below expects. */
5768 {
5772 }
5776 /* If we got a padded type, remove it too. */
5778 gnu_array_object
5780 gnu_array_object);
5784 /* The failure of this assertion will very likely come from a missing
5785 expansion for a packed array access. */
5788 /* First compute the number of dimensions of the array, then
5789 fill the expression array, the order depending on whether
5790 this is a Convention_Fortran array or not. */
5795 ;
5804 else
5812 {
5818 gnu_expr
5819 = emit_index_check
5823 gnat_temp);
5825 gnu_result
5828 /* Array accesses are bound-checked so they cannot trap, but this
5829 is valid only if they are not hoisted ahead of the check. We
5830 need to mark them as no-trap to get decent loop optimizations
5831 in the presence of -fnon-call-exceptions, so we do it when we
5832 know that the original expression had no side-effects. */
5837 }
5841 /* If this is an atomic access on the RHS for which synchronization is
5842 required, build the atomic load. */
5846 }
5850 {
5852 tree gnu_type;
5857 /* Do any implicit dereferences of the prefix and do any needed
5858 range check. */
5863 {
5864 /* Get the bounds of the slice. */
5865 tree gnu_index_type
5869 /* Get the permitted bounds. */
5870 tree gnu_base_index_type
5872 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5874 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
5881 /* Derive a good type to convert everything to. */
5884 /* Test whether the minimum slice value is too small. */
5887 gnu_min_expr),
5889 gnu_base_min_expr));
5891 /* Test whether the maximum slice value is too large. */
5894 gnu_max_expr),
5896 gnu_base_max_expr));
5898 /* Build a slice index check that returns the low bound,
5899 assuming the slice is not empty. */
5900 gnu_expr = emit_check
5905 /* Build a conditional expression that does the index checks and
5906 returns the low bound if the slice is not empty (max >= min),
5907 and returns the naked low bound otherwise (max < min), unless
5908 it is non-constant and the high bound is; this prevents VRP
5909 from inferring bogus ranges on the unlikely path. */
5913 gnu_max_expr),
5915 gnu_min_expr)),
5916 gnu_expr,
5920 }
5921 else
5922 /* Simply return the naked low bound. */
5925 /* If this is a slice with non-constant size of an array with constant
5926 size, set the maximum size for the allocation of temporaries. */
5933 }
5937 {
5941 tree gnu_field;
5945 /* For discriminant references in tagged types always substitute the
5946 corresponding discriminant as the actual selected component. */
5951 /* For discriminant references of untagged types always substitute the
5952 corresponding stored discriminant. */
5956 /* Handle extracting the real or imaginary part of a complex.
5957 The real part is the first field and the imaginary the last. */
5962 else
5963 {
5966 /* If there are discriminants, the prefix might be evaluated more
5967 than once, which is a problem if it has side-effects. */
5974 gnu_result
5978 && lvalue_required_for_attribute_p
5980 }
5984 /* If this is an atomic access on the RHS for which synchronization is
5985 required, build the atomic load. */
5989 }
5993 {
5994 /* The attribute designator. */
5997 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
5998 is a unit, not an object with a GCC equivalent. */
6000 return
6008 }
6012 /* Like 'Access as far as we are concerned. */
6020 {
6021 tree gnu_aggr_type;
6023 /* ??? It is wrong to evaluate the type now, but there doesn't
6024 seem to be any other practical way of doing it. */
6028 gnu_aggr_type = gnu_result_type
6033 gnu_aggr_type
6040 NULL);
6044 gnu_result
6047 gnu_aggr_type);
6050 gnu_aggr_type,
6053 gnu_result
6054 = build_binary_op
6059 (Next
6061 else
6065 }
6073 else
6080 /* Get the operand expression. */
6084 /* If this is a qualified expression for a tagged type, we mark the type
6085 as used. Because of polymorphism, this might be the only reference to
6086 the tagged type in the program while objects have it as dynamic type.
6087 The debugger needs to see it to display these objects properly. */
6091 gnu_result
6095 kind == N_Type_Conversion
6102 /* Skip further processing if the conversion is deemed a no-op. */
6104 {
6107 }
6111 /* If the result is a pointer type, see if we are improperly
6112 converting to a stricter alignment. */
6115 {
6121 post_error_ne_tree_2
6125 }
6127 /* If we are converting a descriptor to a function pointer, first
6128 build the pointer. */
6140 {
6145 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6146 subtype. */
6148 {
6151 }
6154 {
6158 gnu_low
6160 gnu_high
6162 }
6163 else
6168 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6169 ensure that GNU_OBJ is evaluated only once and perform a full range
6170 test. */
6172 gnu_result
6174 else
6175 {
6184 gnu_result
6186 }
6189 gnu_result
6191 }
6199 ? RDIV_EXPR
6206 /* These can either be operations on booleans or on modular types.
6207 Fall through for boolean types since that's the way GNU_CODES is
6208 set up. */
6210 {
6211 enum tree_code code
6222 }
6224 /* ... fall through ... */
6236 {
6240 tree gnu_type;
6246 /* Pending generic support for efficient vector logical operations in
6247 GCC, convert vectors to their representative array type view and
6248 fallthrough. */
6252 /* If this is a comparison operator, convert any references to an
6253 unconstrained array value into a reference to the actual array. */
6255 {
6258 }
6260 /* If this is a shift whose count is not guaranteed to be correct,
6261 we need to adjust the shift count. */
6263 {
6265 tree gnu_max_shift
6272 gnu_rhs
6273 = build_binary_op
6276 gnu_count_type,
6277 gnu_max_shift,
6279 integer_one_node)),
6280 gnu_rhs);
6281 }
6283 /* For right shifts, the type says what kind of shift to do,
6284 so we may need to choose a different type. In this case,
6285 we have to ignore integer overflow lest it propagates all
6286 the way down and causes a CE to be explicitly raised. */
6288 {
6291 }
6294 {
6297 }
6300 {
6306 }
6308 /* Instead of expanding overflow checks for addition, subtraction
6309 and multiplication itself, the front end will leave this to
6310 the back end when Backend_Overflow_Checks_On_Target is set.
6311 As the GCC back end itself does not know yet how to properly
6312 do overflow checking, do it here. The goal is to push
6313 the expansions further into the back end over time. */
6322 else
6323 {
6324 /* Some operations, e.g. comparisons of arrays, generate complex
6325 trees that need to be annotated while they are being built. */
6328 }
6330 /* If this is a logical shift with the shift count not verified,
6331 we must return zero if it is too large. We cannot compensate
6332 above in this case. */
6335 gnu_result
6336 = build_cond_expr
6339 gnu_rhs,
6343 gnu_result);
6344 }
6348 {
6351 tree gnu_false
6355 gnu_result
6357 }
6366 /* This case can apply to a boolean or a modular type.
6367 Fall through for a boolean operand since GNU_CODES is set
6368 up to handle this. */
6370 {
6374 gnu_expr);
6376 }
6378 /* ... fall through ... */
6387 gnu_result
6390 else
6396 {
6398 tree gnu_type;
6403 /* The Expression operand can either be an N_Identifier or
6404 Expanded_Name, which must represent a type, or a
6405 N_Qualified_Expression, which contains both the object type and an
6406 initial value for the object. */
6411 {
6412 Entity_Id gnat_desig_type
6420 gnu_init
6426 else
6427 {
6431 }
6433 /* See the N_Qualified_Expression case for the rationale. */
6438 }
6439 else
6446 ignore_init_type);
6447 }
6450 /**************************/
6451 /* Chapter 5: Statements */
6452 /**************************/
6460 /* When not optimizing, turn null statements from source into gotos to
6461 the next statement that the middle-end knows how to preserve. */
6463 {
6474 }
6475 else
6480 /* Get the LHS and RHS of the statement and convert any reference to an
6481 unconstrained array into a reference to the underlying array. */
6484 /* If the type has a size that overflows, convert this into raise of
6485 Storage_Error: execution shouldn't have gotten here anyway. */
6489 N_Raise_Storage_Error);
6491 gnu_result
6494 else
6495 {
6497 const Entity_Id gnat_type
6499 const bool regular_array_type_p
6501 const bool use_memset_p
6502 = (regular_array_type_p
6506 /* If we'll use memset, we need to find the inner expression. */
6508 {
6509 Node_Id gnat_inner
6513 gnat_inner
6516 }
6517 else
6520 /* If range check is needed, emit code to generate it. */
6523 gnat_node);
6525 /* If atomic synchronization is required, build an atomic store. */
6529 /* Or else, use memset when the conditions are met. */
6531 {
6535 tree size
6540 {
6541 tree mask
6545 }
6547 }
6549 /* Otherwise build a regular assignment. */
6550 else
6551 gnu_result
6554 /* If the assignment type is a regular array and the two sides are
6555 not completely disjoint, play safe and use memmove. But don't do
6556 it for a bit-packed array as it might not be byte-aligned. */
6558 && regular_array_type_p
6560 {
6564 tree size
6570 }
6571 }
6575 {
6578 /* Make the outer COND_EXPR. Avoid non-determinism. */
6587 /* Now make a COND_EXPR for each of the "else if" parts. Put each
6588 into the previous "else" part and point to where to put any
6589 outer "else". Also avoid non-determinism. */
6593 {
6603 }
6606 }
6618 /* The only way to enter the block is to fall through to it. */
6620 {
6627 }
6628 else
6633 gnu_result
6643 {
6646 /* If the subprogram is a function, we must return the expression. */
6648 {
6651 /* If this function has copy-in/copy-out parameters parameters and
6652 doesn't return by invisible reference, get the real object for
6653 the return. See Subprogram_Body_to_gnu. */
6657 else
6660 /* Get the GCC tree for the expression to be returned. */
6663 /* Do not remove the padding from GNU_RET_VAL if the inner type is
6664 self-referential since we want to allocate the fixed size. */
6666 && TYPE_IS_PADDING_P
6668 && CONTAINS_PLACEHOLDER_P
6672 /* If the function returns by direct reference, return a pointer
6673 to the return value. */
6678 /* Otherwise, if it returns an unconstrained array, we have to
6679 allocate a new version of the result and return it. */
6681 {
6684 /* And find out whether this is a candidate for Named Return
6685 Value. If so, record it. */
6687 {
6690 /* Strip useless conversions around the return value. */
6694 /* Strip unpadding around the return value. */
6696 && TYPE_IS_PADDING_P
6700 /* Now apply the test to the return value. */
6702 {
6708 }
6709 }
6712 gnu_ret_val,
6717 }
6719 /* Otherwise, if it returns by invisible reference, dereference
6720 the pointer it is passed using the type of the return value
6721 and build the copy operation manually. This ensures that we
6722 don't copy too much data, for example if the return type is
6723 unconstrained with a maximum size. */
6725 {
6726 tree gnu_ret_deref
6728 gnu_ret_obj);
6733 }
6734 }
6736 else
6739 /* If we have a return label defined, convert this into a branch to
6740 that label. The return proper will be handled elsewhere. */
6742 {
6745 gnu_ret_val));
6750 /* When not optimizing, make sure the return is preserved. */
6753 }
6755 /* Otherwise, build a regular return. */
6756 else
6758 }
6762 gnu_result
6766 /***************************/
6767 /* Chapter 6: Subprograms */
6768 /***************************/
6771 /* Unless there is a freeze node, declare the subprogram. We consider
6772 this a "definition" even though we're not generating code for
6773 the subprogram because we will be making the corresponding GCC
6774 node here. */
6783 /* This subprogram doesn't exist for code generation purposes, but we
6784 have to elaborate the types of any parameters and result, unless
6785 they are imported types (nothing to generate in this case).
6787 The parameter list may contain types with freeze nodes, e.g. not null
6788 subtypes, so the subprogram itself may carry a freeze node, in which
6789 case its elaboration must be deferred. */
6791 /* Process the parameter types first. */
6794 = First_Formal_With_Extras
6802 /* Then the result type, set to Standard_Void_Type for procedures. */
6803 {
6804 Entity_Id gnat_temp_type
6809 }
6815 /* For a child unit identifier go up a level to get the specification.
6816 We get this when we try to find the spec of a child unit package
6817 that is the compilation unit being compiled. */
6831 /************************/
6832 /* Chapter 7: Packages */
6833 /************************/
6849 /* If this is the body of a generic package - do nothing. */
6851 {
6854 }
6865 /********************************/
6866 /* Chapter 8: Visibility Rules */
6867 /********************************/
6871 /* Nothing to do here - but these may appear in list of declarations. */
6875 /*********************/
6876 /* Chapter 9: Tasks */
6877 /*********************/
6888 /*********************************************************/
6889 /* Chapter 10: Program Structure and Compilation Issues */
6890 /*********************************************************/
6893 /* This is not called for the main unit on which gigi is invoked. */
6902 /* Simply process whatever unit is being inserted. */
6905 else
6906 {
6909 }
6916 /***************************/
6917 /* Chapter 11: Exceptions */
6918 /***************************/
6921 /* If there is an At_End procedure attached to this node, and the EH
6922 mechanism is SJLJ, we must have at least a corresponding At_End
6923 handler, unless the No_Exception_Handlers restriction is set. */
6938 else
6943 /* Only for reraise in back-end exceptions mode. */
6950 /* Clear the current exception pointer so that the occurrence won't be
6951 deallocated. */
6990 /******************************/
6991 /* Chapter 12: Generic Units */
6992 /******************************/
7002 /* These nodes can appear on a declaration list but there is nothing to
7003 to be done with them. */
7007 /**************************************************/
7008 /* Chapter 13: Representation Clauses and */
7009 /* Implementation-Dependent Features */
7010 /**************************************************/
7015 /* The only one we need to deal with is 'Address since, for the others,
7016 the front-end puts the information elsewhere. */
7020 /* And we only deal with 'Address if the object has a Freeze node. */
7025 /* Get the value to use as the address and save it as the equivalent
7026 for the object. When it is frozen, gnat_to_gnu_entity will do the
7027 right thing. */
7034 /* We do nothing with these. SEM puts the information elsewhere. */
7040 {
7050 /* First retrieve the 3 operand lists built by the front-end. */
7053 {
7060 }
7064 {
7071 }
7075 gnu_clobbers
7078 gnu_clobbers);
7080 /* Then perform some standard checking and processing on the
7081 operands. In particular, mark them addressable if needed. */
7089 {
7091 constraint
7097 {
7098 /* If the operand is going to end up in memory,
7099 mark it addressable. Note that we don't test
7100 allows_mem like in the input case below; this
7101 is modelled on the C front-end. */
7103 {
7110 }
7111 }
7112 else
7116 }
7119 {
7121 constraint
7127 {
7128 /* If the operand is going to end up in memory,
7129 mark it addressable. */
7131 {
7138 }
7139 }
7140 else
7144 }
7150 }
7151 else
7156 /****************/
7157 /* Added Nodes */
7158 /****************/
7161 /* This construct doesn't define a scope so we don't push a binding
7162 level around the statement list, but we wrap it in a SAVE_EXPR to
7163 protect it from unsharing. Elaborate the expression as part of the
7164 same statement group as the actions so that the type declaration
7165 gets inserted there as well. This ensures that the type elaboration
7166 code is issued past the actions computing values on which it might
7167 depend. */
7177 gnu_result
7202 {
7207 /* If this is a thin pointer, we must first dereference it to create
7208 a fat pointer, then go back below to a thin pointer. The reason
7209 for this is that we need to have a fat pointer someplace in order
7210 to properly compute the size. */
7214 gnu_ptr));
7216 /* If this is a fat pointer, the object must have been allocated with
7217 the template in front of the array. So pass the template address,
7218 and get the total size; do it by converting to a thin pointer. */
7220 gnu_ptr
7222 (TYPE_OBJECT_RECORD_TYPE
7224 gnu_ptr);
7228 /* If this is a thin pointer, the object must have been allocated with
7229 the template in front of the array. So pass the template address,
7230 and get the total size. */
7232 gnu_ptr
7234 gnu_ptr,
7236 byte_position
7237 (DECL_CHAIN
7240 /* If we have a special dynamic constrained subtype on the node, use
7241 it to compute the size; otherwise, use the designated subtype. */
7243 {
7244 gnu_actual_obj_type
7248 gnu_actual_obj_type
7250 gnu_actual_obj_type,
7253 }
7254 else
7257 gnu_result
7260 gnu_obj_type,
7263 gnat_node);
7264 }
7272 else
7277 /* The only validation we currently do on an unchecked conversion is
7278 that of aliasing assumptions. */
7290 /* These nodes should only be present when annotating types. */
7296 /* Other nodes are not supposed to reach here. */
7298 }
7300 /* If we pushed the processing of the elaboration routine, pop it back. */
7304 /* When not optimizing, turn boolean rvalues B into B != false tests
7305 so that the code just below can put the location information of the
7306 reference to B on the inequality operator for better debug info. */
7320 boolean_false_node));
7322 /* Set the location information on the result. Note that we may have
7323 no result if we tried to build a CALL_EXPR node to a procedure with
7324 no side-effects and optimization is enabled. */
7328 /* If we're supposed to return something of void_type, it means we have
7329 something we're elaborating for effect, so just return. */
7333 /* If the result is a constant that overflowed, raise Constraint_Error. */
7335 {
7337 gnu_result
7340 N_Raise_Constraint_Error));
7341 }
7343 /* If the result has side-effects and is of an unconstrained type, make a
7344 SAVE_EXPR so that we can be sure it will only be referenced once. But
7345 this is useless for a call to a function that returns an unconstrained
7346 type with default discriminant, as we cannot compute the size of the
7347 actual returned object. We must do this before any conversions. */
7355 /* Now convert the result to the result type, unless we are in one of the
7356 following cases:
7358 1. If this is the LHS of an assignment or an actual parameter of a
7359 call, return the result almost unmodified since the RHS will have
7360 to be converted to our type in that case, unless the result type
7361 has a simpler size. Likewise if there is just a no-op unchecked
7362 conversion in-between. Similarly, don't convert integral types
7363 that are the operands of an unchecked conversion since we need
7364 to ignore those conversions (for 'Valid).
7366 2. If we have a label (which doesn't have any well-defined type), a
7367 field or an error, return the result almost unmodified. Similarly,
7368 if the two types are record types with the same name, don't convert.
7369 This will be the case when we are converting from a packable version
7370 of a type to its original type and we need those conversions to be
7371 NOPs in order for assignments into these types to work properly.
7373 3. If the type is void or if we have no result, return error_mark_node
7374 to show we have no result.
7376 4. If this a call to a function that returns an unconstrained type with
7377 default discriminant, return the call expression unmodified since we
7378 cannot compute the size of the actual returned object.
7380 5. Finally, if the type of the result is already correct. */
7398 && (CONTAINS_PLACEHOLDER_P
7402 {
7403 /* Remove padding only if the inner object is of self-referential
7404 size: in that case it must be an object of unconstrained type
7405 with a default discriminant and we want to avoid copying too
7406 much data. */
7411 gnu_result);
7412 }
7421 {
7422 /* Remove any padding. */
7425 gnu_result);
7426 }
7434 == gnu_result_type
7436 ;
7441 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7448 }
7449 \f
7450 /* Subroutine of above to push the exception label stack. GNU_STACK is
7451 a pointer to the stack to update and GNAT_LABEL, if present, is the
7452 label to push onto the stack. */
7454 static void
7456 {
7462 }
7463 \f
7464 /* Record the current code position in GNAT_NODE. */
7466 static void
7468 {
7473 }
7475 /* Insert the code for GNAT_NODE at the position saved for that node. */
7477 static void
7479 {
7482 }
7483 \f
7484 /* Start a new statement group chained to the previous group. */
7486 void
7488 {
7491 /* First see if we can get one from the free list. */
7494 else
7500 }
7502 /* Add GNU_STMT to the current statement group. If it is an expression with
7503 no effects, it is ignored. */
7505 void
7507 {
7509 }
7511 /* Similar, but the statement is always added, regardless of side-effects. */
7513 void
7515 {
7517 }
7519 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7521 void
7523 {
7524 /* Do not emit a location for renamings that come from generic instantiation,
7525 they are likely to disturb debugging. */
7530 }
7532 /* Similar, but the statement is always added, regardless of side-effects. */
7534 void
7536 {
7540 }
7542 /* Add a declaration statement for GNU_DECL to the current statement group.
7543 Get SLOC from Entity_Id. */
7545 void
7547 {
7551 /* If this is a variable that Gigi is to ignore, we may have been given
7552 an ERROR_MARK. So test for it. We also might have been given a
7553 reference for a renaming. So only do something for a decl. Also
7554 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7562 /* If we are external or global, we don't want to output the DECL_EXPR for
7563 this DECL node since we already have evaluated the expressions in the
7564 sizes and positions as globals and doing it again would be wrong. */
7566 {
7567 /* Mark everything as used to prevent node sharing with subprograms.
7568 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7569 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7573 {
7577 }
7578 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
7583 }
7584 else
7587 /* If this is a variable and an initializer is attached to it, it must be
7588 valid for the context. Similar to init_const in create_var_decl_1. */
7595 {
7596 /* If GNU_DECL has a padded type, convert it to the unpadded
7597 type so the assignment is done properly. */
7600 else
7607 {
7610 }
7613 }
7614 }
7616 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
7618 static tree
7620 {
7626 /* Don't mark a dummy type as visited because we want to mark its sizes
7627 and fields once it's filled in. */
7635 }
7637 /* Mark nodes rooted at T with TREE_VISITED and types as having their
7638 sized gimplified. We use this to indicate all variable sizes and
7639 positions in global types may not be shared by any subprogram. */
7641 void
7643 {
7645 }
7647 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
7648 set its location to that of GNAT_NODE if present, but with column info
7649 cleared so that conditional branches generated as part of the cleanup
7650 code do not interfere with coverage analysis tools. */
7652 static void
7654 {
7658 }
7660 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
7662 void
7664 {
7667 }
7669 /* Return code corresponding to the current code group. It is normally
7670 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
7671 BLOCK or cleanups were set. */
7673 tree
7675 {
7679 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
7680 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
7681 make a BIND_EXPR. Note that we nest in that because the cleanup may
7682 reference variables in the block. */
7694 /* Remove this group from the stack and add it to the free list. */
7700 }
7702 /* Return whether the current statement group may fall through. */
7706 {
7709 else
7711 }
7713 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
7714 statements.*/
7716 static void
7718 {
7719 Node_Id gnat_node;
7725 }
7727 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
7728 If BINDING_P is true, push and pop a binding level around the list. */
7730 static tree
7732 {
7742 }
7743 \f
7744 /* Generate GIMPLE in place for the expression at *EXPR_P. */
7746 int
7749 {
7752 tree op;
7758 {
7760 /* If this is an aggregate type, build a null pointer of the appropriate
7761 type and dereference it. */
7766 integer_zero_node));
7767 /* Otherwise, just make a VAR_DECL. */
7768 else
7769 {
7772 }
7778 /* We should only do this if we are just elaborating for side-effects,
7779 but we can't know that yet. */
7786 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
7787 is put into static memory. We know that it's going to be read-only
7788 given the semantics we have and it must be in static memory when the
7789 reference is in an elaboration procedure. */
7791 {
7795 }
7802 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
7803 type to a scalar one, explicitly create the local temporary. That's
7804 required if the type is passed by reference. */
7808 {
7817 }
7824 /* The expressions for the RM bounds must be gimplified to ensure that
7825 they are properly elaborated. See gimplify_decl_expr. */
7829 {
7834 {
7839 {
7843 }
7847 {
7851 }
7853 }
7858 }
7860 /* ... fall through ... */
7864 }
7865 }
7867 /* Generate GIMPLE in place for the statement at *STMT_P. */
7869 static enum gimplify_status
7871 {
7875 {
7881 {
7887 /* Build the condition expression from the test, if any. */
7889 {
7890 /* Deal with the optimization hints. */
7894 annot_expr_ivdep_kind));
7898 annot_expr_no_vector_kind));
7902 annot_expr_vector_kind));
7904 gnu_cond
7907 }
7909 /* Set to emit the statements of the loop. */
7912 /* We first emit the start label and then a conditional jump to the
7913 end label if there's a top condition, then the update if it's at
7914 the top, then the body of the loop, then a conditional jump to
7915 the end label if there's a bottom condition, then the update if
7916 it's at the bottom, and finally a jump to the start label and the
7917 definition of the end label. */
7919 gnu_start_label),
7920 stmt_p);
7941 gnu_end_label),
7942 stmt_p);
7944 }
7947 /* Build a statement to jump to the corresponding end label, then
7948 see if it needs to be conditional. */
7957 }
7958 }
7959 \f
7960 /* Force references to each of the entities in packages withed by GNAT_NODE.
7961 Operate recursively but check that we aren't elaborating something more
7962 than once.
7964 This routine is exclusively called in type_annotate mode, to compute DDA
7965 information for types in withed units, for ASIS use. */
7967 static void
7969 {
7972 /* Process each unit only once. As we trace the context of all relevant
7973 units transitively, including generic bodies, we may encounter the
7974 same generic unit repeatedly. */
7978 /* Save entities in all context units. A body may have an implicit_with
7979 on its own spec, if the context includes a child unit, so don't save
7980 the spec twice. */
7987 {
7991 {
8008 }
8010 {
8011 Node_Id gnat_body
8014 /* Retrieve compilation unit node of generic body. */
8019 /* If body is available, elaborate its context. */
8022 }
8023 }
8027 }
8028 \f
8029 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8031 static void
8033 {
8038 /* If this is a package, we need to generate code for the package. */
8040 {
8041 insert_code_for
8045 }
8047 /* Don't do anything for class-wide types as they are always transformed
8048 into their root type. */
8052 /* Check for an old definition. This freeze node might be for an Itype. */
8053 gnu_old
8056 /* If this entity has an address representation clause, GNU_OLD is the
8057 address, so discard it here. */
8061 /* Don't do anything for subprograms that may have been elaborated before
8062 their freeze nodes. This can happen, for example, because of an inner
8063 call in an instance body or because of previous compilation of a spec
8064 for inlining purposes. */
8072 /* If we have a non-dummy type old tree, we have nothing to do, except
8073 aborting if this is the public view of a private type whose full view was
8074 not delayed, as this node was never delayed as it should have been. We
8075 let this happen for concurrent types and their Corresponding_Record_Type,
8076 however, because each might legitimately be elaborated before its own
8077 freeze node, e.g. while processing the other. */
8081 {
8089 }
8091 /* Reset the saved tree, if any, and elaborate the object or type for real.
8092 If there is a full view, elaborate it and use the result. And, if this
8093 is the root type of a class-wide type, reuse it for the latter. */
8095 {
8100 {
8107 {
8110 }
8111 }
8117 }
8121 {
8130 /* Propagate back-annotations from full view to partial view. */
8140 /* The above call may have defined this entity (the simplest example
8141 of this is when we have a private enumeral type since the bounds
8142 will have the public view). */
8145 }
8146 else
8147 {
8148 tree gnu_init
8154 }
8161 /* If we have an old type and we've made pointers to this type, update those
8162 pointers. If this is a Taft amendment type in the main unit, we need to
8163 mark the type as used since other units referencing it don't see the full
8164 declaration and, therefore, cannot mark it as used themselves. */
8166 {
8171 }
8172 }
8173 \f
8174 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8175 We make two passes, one to elaborate anything other than bodies (but
8176 we declare a function if there was no spec). The second pass
8177 elaborates the bodies.
8179 GNAT_END_LIST gives the element in the list past the end. Normally,
8180 this is Empty, but can be First_Real_Statement for a
8181 Handled_Sequence_Of_Statements.
8183 We make a complete pass through both lists if PASS1P is true, then make
8184 the second pass over both lists if PASS2P is true. The lists usually
8185 correspond to the public and private parts of a package. */
8187 static void
8190 {
8192 Node_Id gnat_decl;
8202 {
8203 /* For package specs, we recurse inside the declarations,
8204 thus taking the two pass approach inside the boundary. */
8212 /* Similarly for any declarations in the actions of a
8213 freeze node. */
8215 {
8218 }
8220 /* Package bodies with freeze nodes get their elaboration deferred
8221 until the freeze node, but the code must be placed in the right
8222 place, so record the code position now. */
8230 (Corresponding_Spec
8233 record_code_position
8236 /* We defer most subprogram bodies to the second pass. */
8238 {
8240 {
8246 }
8247 }
8249 /* For bodies and stubs that act as their own specs, the entity
8250 itself must be elaborated in the first pass, because it may
8251 be used in other declarations. */
8253 {
8254 Node_Id gnat_subprog_id
8261 }
8263 /* Concurrent stubs stand for the corresponding subprogram bodies,
8264 which are deferred like other bodies. */
8267 ;
8269 else
8271 }
8273 /* Here we elaborate everything we deferred above except for package bodies,
8274 which are elaborated at their freeze nodes. Note that we must also
8275 go inside things (package specs and freeze nodes) the first pass did. */
8281 {
8297 }
8298 }
8299 \f
8300 /* Make a unary operation of kind CODE using build_unary_op, but guard
8301 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8302 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8303 the operation is to be performed in that type. GNAT_NODE is the gnat
8304 node conveying the source location for which the error should be
8305 signaled. */
8307 static tree
8309 Node_Id gnat_node)
8310 {
8319 }
8321 /* Make a binary operation of kind CODE using build_binary_op, but guard
8322 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8323 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8324 Usually the operation is to be performed in that type. GNAT_NODE is
8325 the GNAT node conveying the source location for which the error should
8326 be signaled. */
8328 static tree
8331 {
8341 /* Assert that the precision is a power of 2. */
8344 /* Prefer a constant or known-positive rhs to simplify checks. */
8350 {
8354 }
8358 /* If we can fold the expression to a constant, just return it.
8359 The caller will deal with overflow, no need to generate a check. */
8364 ? boolean_false_node
8367 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8369 /* Try a few strategies that may be cheaper than the general
8370 code at the end of the function, if the rhs is not known.
8371 The strategies are:
8372 - Call library function for 64-bit multiplication (complex)
8373 - Widen, if input arguments are sufficiently small
8374 - Determine overflow using wrapped result for addition/subtraction. */
8377 {
8378 /* Even for add/subtract double size to get another base type. */
8382 {
8388 }
8392 {
8398 check = build_binary_op
8405 return
8407 }
8410 {
8412 tree wrapped_expr
8418 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8419 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8420 check
8424 boolean_type_node,
8427 return
8429 }
8430 }
8433 {
8435 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8440 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8447 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8452 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8459 /* The check here is designed to be efficient if the rhs is constant,
8460 but it will work for any rhs by using integer division.
8461 Four different check expressions determine whether X * C overflows,
8462 depending on C.
8463 C == 0 => false
8464 C > 0 => X > type_max / C || X < type_min / C
8465 C == -1 => X == type_min
8466 C < -1 => X > type_min / C || X < type_max / C */
8471 check_pos
8474 rhs),
8477 boolean_type_node,
8480 boolean_type_node,
8483 check_neg
8488 type_min),
8491 boolean_type_node,
8494 boolean_type_node,
8500 }
8503 check_pos);
8506 }
8508 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
8509 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
8510 which we have to check. GNAT_NODE is the GNAT node conveying the source
8511 location for which the error should be signaled. */
8513 static tree
8515 {
8519 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
8520 This can for example happen when translating 'Val or 'Value. */
8524 /* Range checks can only be applied to types with ranges. */
8528 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
8529 we can't do anything since we might be truncating the bounds. No
8530 check is needed in this case. */
8536 /* Checked expressions must be evaluated only once. */
8539 /* Note that the form of the check is
8540 (not (expr >= lo)) or (not (expr <= hi))
8541 the reason for this slightly convoluted form is that NaNs
8542 are not considered to be in range in the float case. */
8543 return emit_check
8545 invert_truthvalue
8549 TYPE_MIN_VALUE
8551 invert_truthvalue
8555 TYPE_MAX_VALUE
8558 }
8559 \f
8560 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
8561 we are about to index, GNU_EXPR is the index expression to be checked,
8562 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
8563 has to be checked. Note that for index checking we cannot simply use the
8564 emit_range_check function (although very similar code needs to be generated
8565 in both cases) since for index checking the array type against which we are
8566 checking the indices may be unconstrained and consequently we need to get
8567 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
8568 The place where we need to do that is in subprograms having unconstrained
8569 array formal parameters. GNAT_NODE is the GNAT node conveying the source
8570 location for which the error should be signaled. */
8572 static tree
8575 {
8576 tree gnu_expr_check;
8578 /* Checked expressions must be evaluated only once. */
8581 /* Must do this computation in the base type in case the expression's
8582 type is an unsigned subtypes. */
8585 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
8586 the object we are handling. */
8590 return emit_check
8593 gnu_expr_check,
8595 gnu_low)),
8597 gnu_expr_check,
8599 gnu_high))),
8601 }
8602 \f
8603 /* GNU_COND contains the condition corresponding to an access, discriminant or
8604 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
8605 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
8606 REASON is the code that says why the exception was raised. GNAT_NODE is
8607 the GNAT node conveying the source location for which the error should be
8608 signaled. */
8610 static tree
8612 {
8613 tree gnu_call
8615 tree gnu_result
8619 gnu_expr);
8621 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
8622 we don't need to evaluate it just for the check. */
8626 }
8627 \f
8628 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
8629 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
8630 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
8631 float to integer conversion with truncation; otherwise round.
8632 GNAT_NODE is the GNAT node conveying the source location for which the
8633 error should be signaled. */
8635 static tree
8638 {
8645 /* If we are not doing any checks, the output is an integral type and the
8646 input is not a floating-point type, just do the conversion. This is
8647 required for packed array types and is simpler in all cases anyway. */
8649 && !overflowp
8654 /* First convert the expression to its base type. This
8655 will never generate code, but makes the tests below much simpler.
8656 But don't do this if converting from an integer type to an unconstrained
8657 array type since then we need to get the bounds from the original
8658 (unpacked) type. */
8662 /* If overflow checks are requested, we need to be sure the result will
8663 fit in the output base type. But don't do this if the input
8664 is integer and the output floating-point. */
8667 {
8668 /* Ensure GNU_EXPR only gets evaluated once. */
8676 /* Convert the lower bounds to signed types, so we're sure we're
8677 comparing them properly. Likewise, convert the upper bounds
8678 to unsigned types. */
8692 /* Check each bound separately and only if the result bound
8693 is tighter than the bound on the input type. Note that all the
8694 types are base types, so the bounds must be constant. Also,
8695 the comparison is done in the base type of the input, which
8696 always has the proper signedness. First check for input
8697 integer (which means output integer), output float (which means
8698 both float), or mixed, in which case we always compare.
8699 Note that we have to do the comparison which would *fail* in the
8700 case of an error since if it's an FP comparison and one of the
8701 values is a NaN or Inf, the comparison will fail. */
8708 gnu_cond
8709 = invert_truthvalue
8712 gnu_out_lb)));
8720 gnu_cond
8722 invert_truthvalue
8724 gnu_input,
8726 gnu_out_ub))));
8731 }
8733 /* Now convert to the result base type. If this is a non-truncating
8734 float-to-integer conversion, round. */
8738 {
8744 /* The following calculations depend on proper rounding to even
8745 of each arithmetic operation. In order to prevent excess
8746 precision from spoiling this property, use the widest hardware
8747 floating-point type if FP_ARITH_MAY_WIDEN is true. */
8748 calc_type
8751 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
8755 half_minus_pred_half);
8758 /* If the input is strictly negative, subtract this value
8759 and otherwise add it from the input. For 0.5, the result
8760 is exactly between 1.0 and the machine number preceding 1.0
8761 (for calc_type). Since the last bit of 1.0 is even, this 0.5
8762 will round to 1.0, while all other number with an absolute
8763 value less than 0.5 round to 0.0. For larger numbers exactly
8764 halfway between integers, rounding will always be correct as
8765 the true mathematical result will be closer to the higher
8766 integer compared to the lower one. So, this constant works
8767 for all floating-point numbers.
8769 The reason to use the same constant with subtract/add instead
8770 of a positive and negative constant is to allow the comparison
8771 to be scheduled in parallel with retrieval of the constant and
8772 conversion of the input to the calc_type (if necessary). */
8777 gnu_comp
8779 gnu_add_pred_half
8781 gnu_subtract_pred_half
8785 }
8791 else
8794 /* Finally, do the range check if requested. Note that if the result type
8795 is a modular type, the range check is actually an overflow check. */
8802 }
8803 \f
8804 /* Return true if GNU_EXPR can be directly addressed. This is the case
8805 unless it is an expression involving computation or if it involves a
8806 reference to a bitfield or to an object not sufficiently aligned for
8807 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
8808 be directly addressed as an object of this type.
8810 *** Notes on addressability issues in the Ada compiler ***
8812 This predicate is necessary in order to bridge the gap between Gigi
8813 and the middle-end about addressability of GENERIC trees. A tree
8814 is said to be addressable if it can be directly addressed, i.e. if
8815 its address can be taken, is a multiple of the type's alignment on
8816 strict-alignment architectures and returns the first storage unit
8817 assigned to the object represented by the tree.
8819 In the C family of languages, everything is in practice addressable
8820 at the language level, except for bit-fields. This means that these
8821 compilers will take the address of any tree that doesn't represent
8822 a bit-field reference and expect the result to be the first storage
8823 unit assigned to the object. Even in cases where this will result
8824 in unaligned accesses at run time, nothing is supposed to be done
8825 and the program is considered as erroneous instead (see PR c/18287).
8827 The implicit assumptions made in the middle-end are in keeping with
8828 the C viewpoint described above:
8829 - the address of a bit-field reference is supposed to be never
8830 taken; the compiler (generally) will stop on such a construct,
8831 - any other tree is addressable if it is formally addressable,
8832 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
8834 In Ada, the viewpoint is the opposite one: nothing is addressable
8835 at the language level unless explicitly declared so. This means
8836 that the compiler will both make sure that the trees representing
8837 references to addressable ("aliased" in Ada parlance) objects are
8838 addressable and make no real attempts at ensuring that the trees
8839 representing references to non-addressable objects are addressable.
8841 In the first case, Ada is effectively equivalent to C and handing
8842 down the direct result of applying ADDR_EXPR to these trees to the
8843 middle-end works flawlessly. In the second case, Ada cannot afford
8844 to consider the program as erroneous if the address of trees that
8845 are not addressable is requested for technical reasons, unlike C;
8846 as a consequence, the Ada compiler must arrange for either making
8847 sure that this address is not requested in the middle-end or for
8848 compensating by inserting temporaries if it is requested in Gigi.
8850 The first goal can be achieved because the middle-end should not
8851 request the address of non-addressable trees on its own; the only
8852 exception is for the invocation of low-level block operations like
8853 memcpy, for which the addressability requirements are lower since
8854 the type's alignment can be disregarded. In practice, this means
8855 that Gigi must make sure that such operations cannot be applied to
8856 non-BLKmode bit-fields.
8858 The second goal is achieved by means of the addressable_p predicate,
8859 which computes whether a temporary must be inserted by Gigi when the
8860 address of a tree is requested; if so, the address of the temporary
8861 will be used in lieu of that of the original tree and some glue code
8862 generated to connect everything together. */
8864 static bool
8866 {
8867 /* For an integral type, the size of the actual type of the object may not
8868 be greater than that of the expected type, otherwise an indirect access
8869 in the latter type wouldn't correctly set all the bits of the object. */
8875 /* The size of the actual type of the object may not be smaller than that
8876 of the expected type, otherwise an indirect access in the latter type
8877 would be larger than the object. But only record types need to be
8878 considered in practice for this case. */
8885 {
8890 /* All DECLs are addressable: if they are in a register, we can force
8891 them to memory. */
8896 /* Taking the address of a dereference yields the original pointer. */
8901 /* Taking the address yields a pointer to the constant pool. */
8905 /* Taking the address of a static constructor yields a pointer to the
8906 tree constant pool. */
8918 /* All rvalues are deemed addressable since taking their address will
8919 force a temporary to be created by the middle-end. */
8923 /* The address of a compound expression is that of its 2nd operand. */
8927 /* We accept &COND_EXPR as soon as both operands are addressable and
8928 expect the outcome to be the address of the selected operand. */
8934 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
8935 the field is sufficiently aligned, in case it is subject
8936 to a pragma Component_Alignment. But we don't need to
8937 check the alignment of the containing record, as it is
8938 guaranteed to be not smaller than that of its most
8939 aligned field that is not a bit-field. */
8940 && (!STRICT_ALIGNMENT
8943 /* The field of a padding record is always addressable. */
8957 {
8958 /* This is addressable if we can avoid a copy. */
8962 && (!STRICT_ALIGNMENT
8967 && (!STRICT_ALIGNMENT
8973 }
8977 }
8978 }
8979 \f
8980 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
8981 a separate Freeze node exists, delay the bulk of the processing. Otherwise
8982 make a GCC type for GNAT_ENTITY and set up the correspondence. */
8984 void
8986 {
8987 tree gnu_old
8989 tree gnu_new;
8991 /* If we are to delay elaboration of this type, just do any
8992 elaborations needed for expressions within the declaration and
8993 make a dummy type entry for this node and its Full_View (if
8994 any) in case something points to it. Don't do this if it
8995 has already been done (the only way that can happen is if
8996 the private completion is also delayed). */
9002 {
9006 {
9011 {
9015 }
9016 }
9019 }
9021 /* If we saved away a dummy type for this node it means that this
9022 made the type that corresponds to the full type of an incomplete
9023 type. Clear that type for now and then update the type in the
9024 pointers. */
9026 {
9031 }
9033 /* Now fully elaborate the type. */
9037 /* If we have an old type and we've made pointers to this type, update those
9038 pointers. If this is a Taft amendment type in the main unit, we need to
9039 mark the type as used since other units referencing it don't see the full
9040 declaration and, therefore, cannot mark it as used themselves. */
9042 {
9047 }
9049 /* If this is a record type corresponding to a task or protected type
9050 that is a completion of an incomplete type, perform a similar update
9051 on the type. ??? Including protected types here is a guess. */
9055 {
9056 tree gnu_task_old
9066 }
9067 }
9068 \f
9069 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9070 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9071 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9073 static tree
9075 {
9078 /* We test for GNU_FIELD being empty in the case where a variant
9079 was the last thing since we don't take things off GNAT_ASSOC in
9080 that case. We check GNAT_ASSOC in case we have a variant, but it
9081 has no fields. */
9084 {
9089 /* The expander is supposed to put a single component selector name
9090 in every record component association. */
9093 /* Ignore fields that have Corresponding_Discriminants since we'll
9094 be setting that field in the parent. */
9099 /* Also ignore discriminants of Unchecked_Unions. */
9104 /* Before assigning a value in an aggregate make sure range checks
9105 are done if required. Then convert to the type of the field. */
9111 /* Add the field and expression to the list. */
9113 }
9117 #ifdef ENABLE_CHECKING
9118 /* Verify that every entry in GNU_LIST was used. */
9121 #endif
9124 }
9126 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9127 the first element of an array aggregate. It may itself be an aggregate.
9128 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9129 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9130 for range checking. */
9132 static tree
9134 Entity_Id gnat_component_type)
9135 {
9137 tree gnu_expr;
9141 {
9142 /* If the expression is itself an array aggregate then first build the
9143 innermost constructor if it is part of our array (multi-dimensional
9144 case). */
9150 gnat_component_type);
9151 else
9152 {
9155 /* Before assigning the element to the array, make sure it is
9156 in range. */
9159 }
9166 integer_one_node));
9167 }
9170 }
9171 \f
9172 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9173 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting
9174 of the associations that are from RECORD_TYPE. If we see an internal
9175 record, make a recursive call to fill it in as well. */
9177 static tree
9179 {
9184 {
9187 /* _Parent is an internal field, but may have values in the aggregate,
9188 so check for values first. */
9190 {
9193 }
9196 {
9201 }
9202 else
9203 /* If we have a record subtype, the names will match, but not the
9204 actual FIELD_DECLs. */
9207 {
9210 }
9216 }
9219 }
9220 \f
9221 /* Process a N_Validate_Unchecked_Conversion node. */
9223 static void
9225 {
9229 /* If the target is a pointer type, see if we are either converting from a
9230 non-pointer or from a pointer to a type with a different alias set and
9231 warn if so, unless the pointer has been marked to alias everything. */
9234 {
9244 target_alias_set)))
9245 {
9249 gnat_node);
9252 }
9253 }
9255 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9256 mitigate the problem in this case, so we unconditionally warn. */
9258 {
9259 tree gnu_source_desig_type
9263 tree gnu_target_desig_type
9270 target_alias_set)))
9271 {
9275 gnat_node);
9276 }
9277 }
9278 }
9279 \f
9280 /* EXP is to be treated as an array or record. Handle the cases when it is
9281 an access object and perform the required dereferences. */
9283 static tree
9285 {
9286 /* If the type is a pointer, dereference it. */
9291 /* If we got a padded type, remove it too. */
9296 }
9297 \f
9298 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9299 location and false if it doesn't. In the former case, set the Gigi global
9300 variable REF_FILENAME to the simple debug file name as given by sinput.
9301 If clear_column is true, set column information to 0. */
9303 static bool
9305 {
9310 {
9313 }
9314 else
9315 {
9321 /* We can have zero if pragma Source_Reference is in effect. */
9325 /* Translate the location. */
9327 }
9329 ref_filename
9330 = IDENTIFIER_POINTER
9331 (get_identifier
9335 }
9337 /* Similar to the above, not clearing the column information. */
9339 bool
9341 {
9343 }
9345 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9346 don't do anything if it doesn't correspond to a source location. */
9348 static void
9350 {
9351 location_t locus;
9357 }
9359 /* Similar to the above, not clearing the column information. */
9361 static void
9363 {
9365 }
9367 /* More elaborate version of set_expr_location_from_node to be used in more
9368 general contexts, for example the result of the translation of a generic
9369 GNAT node. */
9371 static void
9373 {
9374 /* Set the location information on the node if it is a real expression.
9375 References can be reused for multiple GNAT nodes and they would get
9376 the location information of their last use. Also make sure not to
9377 overwrite an existing location as it is probably more precise. */
9380 {
9381 CASE_CONVERT:
9390 /* ... fall through ... */
9394 {
9397 }
9399 }
9400 }
9401 \f
9402 /* Return a colon-separated list of encodings contained in encoded Ada
9403 name. */
9407 {
9411 }
9413 /* Extract the Ada name from an encoded name. */
9417 {
9421 }
9422 \f
9423 /* Post an error message. MSG is the error message, properly annotated.
9424 NODE is the node at which to post the error and the node to use for the
9425 '&' substitution. */
9427 void
9429 {
9430 String_Template temp;
9431 String_Pointer sp;
9441 }
9443 /* Similar to post_error, but NODE is the node at which to post the error and
9444 ENT is the node to use for the '&' substitution. */
9446 void
9448 {
9449 String_Template temp;
9450 String_Pointer sp;
9460 }
9462 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
9464 void
9466 {
9469 }
9471 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9472 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9473 most sense. Return true if a sensible assignment was performed. */
9475 static bool
9477 {
9479 location_t end_locus;
9481 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9482 end_locus when there is one. We consider only GNAT nodes with a possible
9483 End_Label attached. If the End_Label actually was unassigned, fallback
9484 on the original node. We'd better assign an explicit sloc associated with
9485 the outer construct in any case. */
9488 {
9501 }
9505 /* Some expanded subprograms have neither an End_Label nor a Sloc
9506 attached. Notify that to callers. For a block statement with no
9507 End_Label, clear column information, so that the tree for a
9508 transient block does not receive the sloc of a source condition. */
9516 {
9527 }
9528 }
9529 \f
9530 /* Similar to post_error_ne, but T is a GCC tree representing the number to
9531 write. If T represents a constant, the text inside curly brackets in
9532 MSG will be output (presumably including a '^'). Otherwise it will not
9533 be output and the text inside square brackets will be output instead. */
9535 void
9537 {
9544 {
9547 }
9548 else
9552 {
9558 ;
9559 else
9561 }
9566 }
9568 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
9570 void
9573 {
9576 }
9577 \f
9578 /* Initialize the table that maps GNAT codes to GCC codes for simple
9579 binary and unary operations. */
9581 static void
9583 {
9609 }
9611 /* Return a label to branch to for the exception type in KIND or NULL_TREE
9612 if none. */
9614 tree
9616 {
9623 else
9625 }
9627 /* Return the decl for the current elaboration procedure. */
9629 tree
9631 {
9633 }