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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 ****************************************************************************/
76 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
77 for fear of running out of stack space. If we need more, we use xmalloc
78 instead. */
79 #define ALLOCA_THRESHOLD 1000
81 /* In configurations where blocks have no end_locus attached, just
82 sink assignments into a dummy global. */
83 #ifndef BLOCK_SOURCE_END_LOCATION
85 #define BLOCK_SOURCE_END_LOCATION(BLOCK) block_end_locus_sink
86 #endif
88 /* Pointers to front-end tables accessed through macros. */
99 /* Highest number in the front-end node table. */
102 /* Current node being treated, in case abort called. */
103 Node_Id error_gnat_node;
105 /* True when gigi is being called on an analyzed but unexpanded
106 tree, and the only purpose of the call is to properly annotate
107 types with representation information. */
110 /* Current filename without path. */
114 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
117 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
118 of unconstrained array IN parameters to avoid emitting a great deal of
119 redundant instructions to recompute them each time. */
123 tree first;
124 tree last;
125 tree length;
126 };
133 bitmap named_ret_val;
136 };
138 #define f_parm_attr_cache \
139 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
141 #define f_named_ret_val \
142 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
144 #define f_other_ret_val \
145 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
147 #define f_gnat_ret \
148 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
150 /* A structure used to gather together information about a statement group.
151 We use this to gather related statements, for example the "then" part
152 of a IF. In the case where it represents a lexical scope, we may also
153 have a BLOCK node corresponding to it and/or cleanups. */
160 };
164 /* List of unused struct stmt_group nodes. */
167 /* A structure used to record information on elaboration procedures
168 we've made and need to process.
170 ??? gnat_node should be Node_Id, but gengtype gets confused. */
176 };
180 /* Stack of exception pointer variables. Each entry is the VAR_DECL
181 that stores the address of the raised exception. Nonzero means we
182 are in an exception handler. Not used in the zero-cost case. */
185 /* In ZCX case, current exception pointer. Used to re-raise it. */
188 /* Stack for storing the current elaboration procedure decl. */
191 /* Stack of labels to be used as a goto target instead of a return in
192 some functions. See processing for N_Subprogram_Body. */
195 /* Stack of variable for the return value of a function with copy-in/copy-out
196 parameters. See processing for N_Subprogram_Body. */
199 /* Structure used to record information for a range check. */
201 tree low_bound;
202 tree high_bound;
203 tree type;
204 tree invariant_cond;
205 };
210 /* Structure used to record information for a loop. */
212 tree stmt;
213 tree loop_var;
215 };
220 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
223 /* The stacks for N_{Push,Pop}_*_Label. */
228 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
265 /* Hooks for debug info back-ends, only supported and used in a restricted set
266 of configurations. */
269 \f
270 /* This is the main program of the back-end. It sets up all the table
271 structures and then generates code. */
273 void
286 Nat number_file,
288 Entity_Id standard_boolean,
289 Entity_Id standard_integer,
290 Entity_Id standard_character,
291 Entity_Id standard_long_long_float,
292 Entity_Id standard_exception_type,
293 Int gigi_operating_mode)
294 {
295 Node_Id gnat_iter;
296 Entity_Id gnat_literal;
316 {
317 /* Use the identifier table to make a permanent copy of the filename as
318 the name table gets reallocated after Gigi returns but before all the
319 debugging information is output. The __gnat_to_canonical_file_spec
320 call translates filenames from pragmas Source_Reference that contain
321 host style syntax not understood by gdb. */
323 = IDENTIFIER_POINTER
324 (get_identifier
325 (__gnat_to_canonical_file_spec
328 /* We rely on the order isomorphism between files and line maps. */
331 /* We create the line map for a source file at once, with a fixed number
332 of columns chosen to avoid jumping over the next power of 2. */
337 }
341 /* Declare the name of the compilation unit as the first global
342 name in order to make the middle-end fully deterministic. */
346 /* Initialize ourselves. */
351 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
352 errors. */
354 {
357 }
359 /* Enable GNAT stack checking method if needed */
363 /* Retrieve alignment settings. */
367 /* Record the builtin types. Define `integer' and `character' first so that
368 dbx will output them first. */
374 /* Save the type we made for integer as the type for Standard.Integer. */
379 /* Likewise for character as the type for Standard.Character. */
384 /* Likewise for boolean as the type for Standard.Boolean. */
408 /* Now declare run-time functions. */
411 /* malloc is a function declaration tree for a function to allocate
412 memory. */
413 malloc_decl
419 /* free is a function declaration tree for a function to free memory. */
420 free_decl
423 ptr_type_node,
424 NULL_TREE),
426 Empty);
428 /* This is used for 64-bit multiplication with overflow checking. */
430 mulv64_decl
435 Empty);
437 /* Name of the _Parent field in tagged record types. */
440 /* Name of the Exception_Data type defined in System.Standard_Library. */
441 exception_data_name_id
444 /* Make the types and functions used for exception processing. */
445 jmpbuf_type
451 /* Functions to get and set the jumpbuf pointer for the current thread. */
452 get_jmpbuf_decl
453 = create_subprog_decl
459 set_jmpbuf_decl
460 = create_subprog_decl
463 NULL_TREE),
467 /* setjmp returns an integer and has one operand, which is a pointer to
468 a jmpbuf. */
469 setjmp_decl
470 = create_subprog_decl
473 NULL_TREE),
478 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
479 address. */
480 update_setjmp_buf_decl
481 = create_subprog_decl
488 /* Hooks to call when entering/leaving an exception handler. */
491 begin_handler_decl
497 end_handler_decl
503 unhandled_except_decl
505 NULL_TREE,
510 reraise_zcx_decl
514 /* Indicate that these never return. */
521 /* If in no exception handlers mode, all raise statements are redirected to
522 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
523 this procedure will never be called in this mode. */
525 {
526 tree decl
527 = create_subprog_decl
530 build_pointer_type
540 }
541 else
542 {
543 /* Otherwise, make one decl for each exception reason. */
549 i == CE_Index_Check_Failed
553 }
555 /* Set the types that GCC and Gigi use from the front end. */
558 /* Make other functions used for exception processing. */
559 get_excptr_decl
560 = create_subprog_decl
563 NULL_TREE),
567 set_exception_parameter_decl
568 = create_subprog_decl
571 NULL_TREE),
574 raise_nodefer_decl
575 = create_subprog_decl
579 NULL_TREE),
582 /* Indicate that it never returns. */
587 TYPE_QUAL_VOLATILE);
589 /* Build the special descriptor type and its null node if needed. */
591 {
603 {
604 tree field
611 elt--;
612 }
617 }
619 longest_float_type_node
622 /* Dummy objects to materialize "others" and "all others" in the exception
623 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
624 the types to use. */
625 others_decl
628 unsigned_char_type_node,
631 all_others_decl
634 unsigned_char_type_node,
637 unhandled_others_decl
640 unsigned_char_type_node,
645 /* Install the builtins we might need, either internally or as
646 user available facilities for Intrinsic imports. */
654 /* Process any Pragma Ident for the main unit. */
659 /* If we are using the GCC exception mechanism, let GCC know. */
663 /* Initialize the GCC support for FP operations. */
666 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
670 /* Save the current optimization options again after the above possible
671 global_options changes. */
675 /* Now translate the compilation unit proper. */
678 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
679 the very end to avoid having to second-guess the front-end when we run
680 into dummy nodes during the regular processing. */
685 /* Finally see if we have any elaboration procedures to deal with. */
687 {
690 /* We should have a BIND_EXPR but it may not have any statements in it.
691 If it doesn't have any, we have nothing to do except for setting the
692 flag on the GNAT node. Otherwise, process the function as others. */
698 else
699 {
703 }
704 }
706 /* Destroy ourselves. */
710 /* We cannot track the location of errors past this point. */
712 }
713 \f
714 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
715 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
717 static tree
719 {
728 {
730 ftype
732 build_pointer_type
735 }
736 else
737 {
742 ftype
744 build_pointer_type
748 }
750 result
755 /* Indicate that it never returns. */
762 }
763 \f
764 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
765 an N_Attribute_Reference. */
767 static int
769 {
771 {
811 }
812 }
814 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
815 is the type that will be used for GNAT_NODE in the translated GNU tree.
816 CONSTANT indicates whether the underlying object represented by GNAT_NODE
817 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
818 whether its value is the address of a constant and ALIASED whether it is
819 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
821 The function climbs up the GNAT tree starting from the node and returns 1
822 upon encountering a node that effectively requires an lvalue downstream.
823 It returns int instead of bool to facilitate usage in non-purely binary
824 logic contexts. */
826 static int
829 {
833 {
843 /* If the parameter is by reference, an lvalue is required. */
849 /* Only the array expression can require an lvalue. */
853 /* ??? Consider that referencing an indexed component with a variable
854 index forces the whole aggregate to memory. Note that testing only
855 for literals is conservative, any static expression in the RM sense
856 could probably be accepted with some additional work. */
866 /* ... fall through ... */
869 /* Only the array expression can require an lvalue. */
883 /* We need to preserve addresses through a renaming. */
887 /* We cannot use a constructor if this is an atomic object because
888 the actual assignment might end up being done component-wise. */
892 /* We don't use a constructor if this is a class-wide object
893 because the effective type of the object is the equivalent
894 type of the class-wide subtype and it smashes most of the
895 data into an array of bytes to which we cannot convert. */
900 /* We cannot use a constructor if the LHS is an atomic object because
901 the actual assignment might end up being done component-wise. */
912 /* ... fall through ... */
916 /* We must look through all conversions because we may need to bypass
917 an intermediate conversion that is meant to be purely formal. */
923 /* We should only reach here through the N_Qualified_Expression case.
924 Force an lvalue for composite types since a block-copy to the newly
925 allocated area of memory is made. */
929 /* We look through dereferences for address of constant because we need
930 to handle the special cases listed above. */
936 /* ... fall through ... */
940 }
943 }
945 /* Return true if T is a constant DECL node that can be safely replaced
946 by its initializer. */
948 static bool
950 {
954 /* Return false for aggregate types that contain a placeholder since
955 their initializers cannot be manipulated easily. */
962 }
964 /* Return an expression equivalent to EXP but where constant DECL nodes
965 have been replaced by their initializer. */
967 static tree
969 {
971 tree op0;
974 {
1011 }
1014 }
1016 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1017 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1018 to where we should place the result type. */
1020 static tree
1022 {
1026 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1027 specific circumstances only, so evaluated lazily. < 0 means
1028 unknown, > 0 means known true, 0 means known false. */
1031 /* If GNAT_NODE is a constant, whether we should use the initialization
1032 value instead of the constant entity, typically for scalars with an
1033 address clause when the parent doesn't require an lvalue. */
1036 /* If the Etype of this node does not equal the Etype of the Entity,
1037 something is wrong with the entity map, probably in generic
1038 instantiation. However, this does not apply to types. Since we sometime
1039 have strange Ekind's, just do this test for objects. Also, if the Etype of
1040 the Entity is private, the Etype of the N_Identifier is allowed to be the
1041 full type and also we consider a packed array type to be the same as the
1042 original type. Similarly, a class-wide type is equivalent to a subtype of
1043 itself. Finally, if the types are Itypes, one may be a copy of the other,
1044 which is also legal. */
1059 == Packed_Array_Impl_Type
1068 /* If this is a reference to a deferred constant whose partial view is an
1069 unconstrained private type, the proper type is on the full view of the
1070 constant, not on the full view of the type, which may be unconstrained.
1072 This may be a reference to a type, for example in the prefix of the
1073 attribute Position, generated for dispatching code (see Make_DT in
1074 exp_disp,adb). In that case we need the type itself, not is parent,
1075 in particular if it is a derived type */
1082 {
1085 }
1086 else
1087 {
1088 /* We want to use the Actual_Subtype if it has already been elaborated,
1089 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1090 simplify things. */
1098 else
1100 }
1102 /* Expand the type of this identifier first, in case it is an enumeral
1103 literal, which only get made when the type is expanded. There is no
1104 order-of-elaboration issue here. */
1107 /* If this is a non-imported elementary constant with an address clause,
1108 retrieve the value instead of a pointer to be dereferenced unless
1109 an lvalue is required. This is generally more efficient and actually
1110 required if this is a static expression because it might be used
1111 in a context where a dereference is inappropriate, such as a case
1112 statement alternative or a record discriminant. There is no possible
1113 volatile-ness short-circuit here since Volatile constants must be
1114 imported per C.6. */
1119 {
1123 }
1126 {
1127 /* If this is a deferred constant, the initializer is attached to
1128 the full view. */
1133 }
1134 else
1137 /* Some objects (such as parameters passed by reference, globals of
1138 variable size, and renamed objects) actually represent the address
1139 of the object. In that case, we must do the dereference. Likewise,
1140 deal with parameters to foreign convention subprograms. */
1145 {
1148 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1151 gnu_result
1154 /* If it's a CONST_DECL, return the underlying constant like below. */
1161 /* If it's a renaming pointer, get to the renamed object. */
1167 /* Otherwise, do the final dereference. */
1168 else
1169 {
1179 }
1180 }
1182 /* If we have a constant declaration and its initializer, try to return the
1183 latter to avoid the need to call fold in lots of places and the need for
1184 elaboration code if this identifier is used as an initializer itself. */
1186 {
1192 /* If there is a (corresponding) variable or this is the address of a
1193 constant, we only want to return the initializer if an lvalue isn't
1194 required. Evaluate this now if we have not already done so. */
1196 require_lvalue
1200 /* Finally retrieve the initializer if this is deemed valid. */
1203 }
1205 /* But for a constant renaming we couldn't do that incrementally for its
1206 definition because of the need to return an lvalue so, if the present
1207 context doesn't itself require an lvalue, we try again here. */
1211 {
1213 require_lvalue
1218 }
1220 /* The GNAT tree has the type of a function set to its result type, so we
1221 adjust here. Also use the type of the result if the Etype is a subtype
1222 that is nominally unconstrained. Likewise if this is a deferred constant
1223 of a discriminated type whose full view can be elaborated statically, to
1224 avoid problematic conversions to the nominal subtype. But remove any
1225 padding from the resulting type. */
1232 {
1236 }
1241 }
1242 \f
1243 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1244 any statements we generate. */
1246 static tree
1248 {
1251 Node_Id gnat_temp;
1253 /* Do nothing if we are just annotating types and check for (and ignore)
1254 unrecognized pragmas. */
1261 {
1263 /* Do nothing at top level: all such variables are already viewable. */
1270 {
1274 machine_mode mode;
1276 #ifdef ASM_COMMENT_START
1278 #endif
1283 /* Use the value only if it fits into a normal register,
1284 otherwise use the address. */
1293 #ifdef ASM_COMMENT_START
1299 NULL);
1302 #endif
1304 asm_constraint,
1305 NULL_TREE,
1306 tree_cons
1314 }
1321 {
1325 {
1348 }
1349 }
1355 {
1373 }
1383 {
1384 Node_Id gnat_expr;
1385 /* Preserve the location of the pragma. */
1389 diagnostic_t kind;
1394 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1396 {
1398 {
1411 }
1414 }
1416 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1418 {
1420 {
1431 }
1433 /* Deal with optional pattern (but ignore Reason => "..."). */
1436 {
1437 /* pragma Warnings (On | Off, Name) is handled differently. */
1442 }
1443 else
1447 }
1449 else
1452 /* This is the same implementation as in the C family of compilers. */
1454 {
1462 option_index++)
1466 {
1469 }
1470 }
1471 else
1478 }
1483 }
1486 }
1487 \f
1489 /* Check the inlining status of nested function FNDECL in the current context.
1491 If a non-inline nested function is referenced from an inline external
1492 function, we cannot honor both requests at the same time without cloning
1493 the nested function in the current unit since it is private to its unit.
1494 We could inline it as well but it's probably better to err on the side
1495 of too little inlining.
1497 This must be invoked only on nested functions present in the source code
1498 and not on nested functions generated by the compiler, e.g. finalizers,
1499 because they are not marked inline and we don't want them to block the
1500 inlining of the parent function. */
1502 static void
1504 {
1506 && current_function_decl
1509 {
1515 {
1518 }
1519 else
1520 {
1522 fndecl);
1524 }
1528 }
1529 }
1530 \f
1531 /* Return an expression for the length of TYPE, an integral type, computed in
1532 RESULT_TYPE, another integral type.
1534 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1535 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1536 which would only overflow in much rarer cases, for extremely large arrays
1537 we expect never to encounter in practice. Besides, the former computation
1538 required the use of potentially constraining signed arithmetics while the
1539 latter does not. Note that the comparison must be done in the original
1540 base index type in order to avoid any overflow during the conversion. */
1542 static tree
1544 {
1549 tree length
1555 length
1561 }
1563 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1564 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1565 where we should place the result type. ATTRIBUTE is the attribute ID. */
1567 static tree
1569 {
1575 /* ??? If this is an access attribute for a public subprogram to be used in
1576 a dispatch table, do not translate its type as it's useless in this case
1577 and the parameter types might be incomplete types coming from a limited
1578 context in Ada 2012 (AI05-0151). */
1586 else
1590 /* If the input is a NULL_EXPR, make a new one. */
1592 {
1596 }
1599 {
1602 /* These are just conversions since representation clauses for
1603 enumeration types are handled in the front-end. */
1604 {
1610 }
1615 /* These just add or subtract the constant 1 since representation
1616 clauses for enumeration types are handled in the front-end. */
1621 {
1623 gnu_expr
1624 = emit_check
1626 gnu_expr,
1627 attribute == Attr_Pred
1631 }
1633 gnu_result
1641 /* Conversions don't change addresses but can cause us to miss the
1642 COMPONENT_REF case below, so strip them off. */
1646 /* If we are taking 'Address of an unconstrained object, this is the
1647 pointer to the underlying array. */
1651 /* If we are building a static dispatch table, we have to honor
1652 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1653 with the C++ ABI. We do it in the non-static case as well,
1654 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1657 {
1659 /* Descriptors can only be built here for top-level functions. */
1667 /* If we're not going to build the descriptor, we have to retrieve
1668 the one which will be built by the linker (or by the compiler
1669 later if a static chain is requested). */
1671 {
1674 gnu_result);
1676 }
1683 {
1685 {
1689 }
1690 else
1696 elt--;
1697 }
1701 }
1703 /* ... fall through ... */
1709 gnu_result
1716 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1717 don't try to build a trampoline. */
1719 {
1724 }
1726 /* For 'Access, issue an error message if the prefix is a C++ method
1727 since it can use a special calling convention on some platforms,
1728 which cannot be propagated to the access type. */
1733 gnat_node);
1735 /* For other address attributes applied to a nested function,
1736 find an inner ADDR_EXPR and annotate it so that we can issue
1737 a useful warning with -Wtrampolines. */
1739 {
1744 {
1747 /* Also check the inlining status. */
1750 /* Check that we're not violating the No_Implicit_Dynamic_Code
1751 restriction. Be conservative if we don't know anything
1752 about the trampoline strategy for the target. */
1754 }
1755 }
1759 {
1761 tree gnu_obj_type;
1765 /* If this is fat pointer, the object must have been allocated with the
1766 template in front of the array. So compute the template address; do
1767 it by converting to a thin pointer. */
1769 gnu_ptr
1771 (TYPE_OBJECT_RECORD_TYPE
1773 gnu_ptr);
1777 /* If this is a thin pointer, the object must have been allocated with
1778 the template in front of the array. So compute the template address
1779 and return it. */
1781 gnu_ptr
1783 gnu_ptr,
1785 byte_position
1786 (DECL_CHAIN
1790 }
1799 /* Remove NOPs and conversions between original and packable version
1800 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1801 to see if a COMPONENT_REF was involved. */
1806 == RECORD_TYPE
1815 /* Replace an unconstrained array type with the type of the underlying
1816 array. We can't do this with a call to maybe_unconstrained_array
1817 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1818 use the record type that will be used to allocate the object and its
1819 template. */
1821 {
1825 }
1827 /* If we're looking for the size of a field, return the field size. */
1831 /* Otherwise, if the prefix is an object, or if we are looking for
1832 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1833 GCC size of the type. We make an exception for padded objects,
1834 as we do not take into account alignment promotions for the size.
1835 This is in keeping with the object case of gnat_to_gnu_entity. */
1841 {
1842 /* If this is a dereference and we have a special dynamic constrained
1843 subtype on the prefix, use it to compute the size; otherwise, use
1844 the designated subtype. */
1846 {
1847 Node_Id gnat_actual_subtype
1849 tree gnu_ptr_type
1854 {
1855 tree gnu_actual_obj_type
1857 gnu_type
1859 gnu_actual_obj_type,
1862 }
1863 }
1866 }
1868 /* Otherwise, the result is the RM size of the type. */
1869 else
1872 /* Deal with a self-referential size by returning the maximum size for
1873 a type and by qualifying the size with the object otherwise. */
1875 {
1878 else
1880 }
1882 /* If the type contains a template, subtract its size. */
1888 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1896 {
1909 else
1910 {
1915 /* If the default alignment of "double" or larger scalar types is
1916 specifically capped and there is an alignment clause neither
1917 on the type nor on the prefix itself, return the cap. */
1919 is_capped_double
1922 is_capped_double
1924 else
1934 else
1936 }
1939 }
1948 {
1955 else
1958 }
1960 /* ... fall through ... */
1963 {
1971 /* Make sure any implicit dereference gets done. */
1975 /* We treat unconstrained array In parameters specially. We also note
1976 whether we are dereferencing a pointer to unconstrained array. */
1979 {
1981 /* This is the direct case. */
1987 /* This is the indirect case. Note that we need to be sure that
1988 the access value cannot be null as we'll hoist the load. */
1991 {
1994 }
1995 else
2001 }
2003 /* If the prefix is the view conversion of a constrained array to an
2004 unconstrained form, we retrieve the constrained array because we
2005 might not be able to substitute the PLACEHOLDER_EXPR coming from
2006 the conversion. This can occur with the 'Old attribute applied
2007 to a parameter with an unconstrained type, which gets rewritten
2008 into a constrained local variable very late in the game. */
2011 && !CONTAINS_PLACEHOLDER_P
2014 else
2021 {
2023 tree gnu_type_temp;
2029 ;
2032 }
2039 /* When not optimizing, look up the slot associated with the parameter
2040 and the dimension in the cache and create a new one on failure.
2041 Don't do this when the actual subtype needs debug info (this happens
2042 with -gnatD): in elaborate_expression_1, we create variables that
2043 hold the bounds, so caching attributes isn't very interesting and
2044 causes dependency issues between these variables and cached
2045 expressions. */
2050 {
2056 {
2061 }
2062 }
2064 /* Return the cached expression or build a new one. */
2066 {
2068 {
2071 }
2073 gnu_result
2075 }
2078 {
2080 {
2083 }
2085 gnu_result
2087 }
2090 {
2092 {
2095 }
2097 gnu_result
2099 gnu_result_type);
2100 }
2102 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2103 handling. Note that these attributes could not have been used on
2104 an unconstrained array type. */
2107 /* Cache the expression we have just computed. Since we want to do it
2108 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2109 create the temporary in the outermost binding level. We will make
2110 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2111 paths by forcing its evaluation on entry of the function. */
2113 {
2114 gnu_result
2117 {
2133 }
2134 }
2136 /* Otherwise, evaluate it each time it is referenced. */
2137 else
2139 {
2142 /* If we are dereferencing a pointer to unconstrained array, we
2143 need to capture the value because the pointed-to bounds may
2144 subsequently be released. */
2146 gnu_result
2152 /* Set the source location onto the predicate of the condition
2153 but not if the expression is cached to avoid messing up the
2154 debug info. */
2158 gnat_node);
2163 }
2166 }
2173 {
2174 HOST_WIDE_INT bitsize;
2175 HOST_WIDE_INT bitpos;
2176 tree gnu_offset;
2177 tree gnu_field_bitpos;
2178 tree gnu_field_offset;
2179 tree gnu_inner;
2180 machine_mode mode;
2187 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2188 the result is 0. Don't allow 'Bit on a bare component, though. */
2192 {
2195 }
2197 else
2206 {
2214 {
2215 gnu_field_bitpos
2218 gnu_field_offset
2221 }
2222 }
2224 {
2227 }
2228 else
2229 {
2232 }
2235 {
2249 /* ??? Avoid a large unsigned result that will overflow when
2250 converted to the signed universal_integer. */
2253 else
2254 gnu_result
2261 }
2263 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2264 handling. */
2267 }
2271 {
2277 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2278 a NaN so we implement the semantics of C99 f{min,max} to make it
2279 predictable in this case: if either operand is a NaN, the other
2280 is returned; if both operands are NaN's, a NaN is returned. */
2283 {
2289 /* If the operands have side-effects, they need to be evaluated
2290 only once in spite of the multiple references in the result. */
2298 integer_zero_node);
2302 integer_zero_node);
2312 /* If the operands have side-effects, they need to be evaluated
2313 before doing the tests above since the place they otherwise
2314 would end up being evaluated at run time could be wrong. */
2316 gnu_result
2320 gnu_result
2322 }
2323 else
2327 }
2353 /* Note this size cannot be self-referential. */
2363 /* What we want is the offset of the ARRAY field in the record
2364 that the thin pointer designates. */
2372 /* This is just a zero cast to the pointer type for our prefix and
2373 dereferenced. */
2375 gnu_result
2378 integer_zero_node));
2383 {
2390 {
2395 ;
2396 }
2404 && (DECL_BY_COMPONENT_PTR_P
2408 }
2412 /* We treat Model as identical to Machine. This is true for at least
2413 IEEE and some other nice floating-point systems. */
2415 /* ... fall through ... */
2418 /* The trick is to force the compiler to store the result in memory so
2419 that we do not have extra precision used. But do this only when this
2420 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2421 the type is lower than that of the longest floating-point type. */
2428 && fp_arith_may_widen
2431 {
2433 tree field
2443 asm_expr
2455 gnu_result
2459 }
2466 /* This can be a random address so build an alias-all pointer type. */
2467 gnu_expr
2470 gnu_expr);
2475 /* This abort means that we have an unimplemented attribute. */
2477 }
2479 /* If this is an attribute where the prefix was unused, force a use of it if
2480 it has a side-effect. But don't do it if the prefix is just an entity
2481 name. However, if an access check is needed, we must do it. See second
2482 example in AARM 11.6(5.e). */
2486 gnu_result
2491 }
2492 \f
2493 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2494 to a GCC tree, which is returned. */
2496 static tree
2498 {
2500 Node_Id gnat_when;
2501 location_t end_locus;
2507 /* The range of values in a case statement is determined by the rules in
2508 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2509 of the expression. One exception arises in the case of a simple name that
2510 is parenthesized. This still has the Etype of the name, but since it is
2511 not a name, para 7 does not apply, and we need to go to the base type.
2512 This is the only case where parenthesization affects the dynamic
2513 semantics (i.e. the range of possible values at run time that is covered
2514 by the others alternative).
2516 Another exception is if the subtype of the expression is non-static. In
2517 that case, we also have to use the base type. */
2523 /* We build a SWITCH_EXPR that contains the code with interspersed
2524 CASE_LABEL_EXPRs for each label. */
2533 {
2535 Node_Id gnat_choice;
2537 /* First compile all the different case choices for the current WHEN
2538 alternative. */
2542 {
2547 {
2562 /* This represents either a subtype range or a static value of
2563 some kind; Ekind says which. */
2565 {
2571 }
2573 /* ... fall through ... */
2585 }
2587 /* Everything should be folded into constants at this point. */
2592 gnat_choice);
2594 }
2596 /* This construct doesn't define a scope so we shouldn't push a binding
2597 level around the statement list. Except that we have always done so
2598 historically and this makes it possible to reduce stack usage. As a
2599 compromise, we keep doing it for case statements, for which this has
2600 never been problematic, but not for case expressions in Ada 2012. */
2602 {
2603 const bool is_case_expression
2605 tree group
2610 {
2615 }
2616 }
2617 }
2619 /* Now emit a definition of the label the cases branch to, if any. */
2626 }
2627 \f
2628 /* Find out whether VAR is an iteration variable of an enclosing loop in the
2629 current function. If so, push a range_check_info structure onto the stack
2630 of this enclosing loop and return it. Otherwise, return NULL. */
2634 {
2650 i--)
2655 {
2659 }
2662 }
2664 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2665 false, or the maximum value if MAX is true, of TYPE. */
2667 static bool
2669 {
2676 val = (max
2685 else
2687 }
2689 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2690 If REVERSE is true, minimum value is taken as maximum value. */
2694 {
2696 }
2698 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2699 If REVERSE is true, maximum value is taken as minimum value. */
2703 {
2705 }
2707 /* Return true if VAL1 can be lower than VAL2. */
2709 static bool
2711 {
2725 }
2727 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2728 to a GCC tree, which is returned. */
2730 static tree
2732 {
2739 tree gnu_result;
2741 /* Push the loop_info structure associated with the LOOP_STMT. */
2744 /* Set location information for statement and end label. */
2750 /* Save the statement for later reuse. */
2753 /* Set the condition under which the loop must keep going.
2754 For the case "LOOP .... END LOOP;" the condition is always true. */
2756 ;
2758 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2763 /* Otherwise we have an iteration scheme and the condition is given by the
2764 bounds of the subtype of the iteration variable. */
2765 else
2766 {
2780 /* We must disable modulo reduction for the iteration variable, if any,
2781 in order for the loop comparison to be effective. */
2783 {
2789 }
2790 else
2791 {
2797 }
2799 /* We use two different strategies to translate the loop, depending on
2800 whether optimization is enabled.
2802 If it is, we generate the canonical loop form expected by the loop
2803 optimizer and the loop vectorizer, which is the do-while form:
2805 ENTRY_COND
2806 loop:
2807 TOP_UPDATE
2808 BODY
2809 BOTTOM_COND
2810 GOTO loop
2812 This avoids an implicit dependency on loop header copying and makes
2813 it possible to turn BOTTOM_COND into an inequality test.
2815 If optimization is disabled, loop header copying doesn't come into
2816 play and we try to generate the loop form with the fewer conditional
2817 branches. First, the default form, which is:
2819 loop:
2820 TOP_COND
2821 BODY
2822 BOTTOM_UPDATE
2823 GOTO loop
2825 It should catch most loops with constant ending point. Then, if we
2826 cannot, we try to generate the shifted form:
2828 loop:
2829 TOP_COND
2830 TOP_UPDATE
2831 BODY
2832 GOTO loop
2834 which should catch loops with constant starting point. Otherwise, if
2835 we cannot, we generate the fallback form:
2837 ENTRY_COND
2838 loop:
2839 BODY
2840 BOTTOM_COND
2841 BOTTOM_UPDATE
2842 GOTO loop
2844 which works in all cases. */
2847 {
2848 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2849 overflow. */
2851 ;
2853 /* Otherwise, use the do-while form with the help of a special
2854 induction variable in the unsigned version of the base type
2855 or the unsigned version of the size type, whichever is the
2856 largest, in order to have wrap-around arithmetics for it. */
2857 else
2858 {
2861 gnu_base_type
2863 else
2870 }
2872 gnu_first
2874 gnu_one_node);
2877 }
2878 else
2879 {
2880 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2882 ;
2884 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2885 GNU_LAST-1 does. */
2888 {
2889 gnu_first
2891 gnu_one_node);
2892 gnu_last
2894 gnu_one_node);
2896 }
2898 /* Otherwise, use the fallback form. */
2899 else
2901 }
2903 /* If we use the BOTTOM_COND, we can turn the test into an inequality
2904 test but we may have to add ENTRY_COND to protect the empty loop. */
2906 {
2909 {
2910 gnu_cond_expr
2916 }
2917 }
2919 /* Open a new nesting level that will surround the loop to declare the
2920 iteration variable. */
2924 /* If we use the special induction variable, create it and set it to
2925 its initial value. Morever, the regular iteration variable cannot
2926 itself be initialized, lest the initial value wrapped around. */
2928 {
2929 gnu_loop_iv
2933 }
2934 else
2937 /* Declare the iteration variable and set it to its initial value. */
2942 {
2945 }
2948 /* Do all the arithmetics in the base type. */
2951 /* Set either the top or bottom exit condition. */
2955 gnu_last);
2956 else
2959 gnu_last);
2961 /* Set either the top or bottom update statement and give it the source
2962 location of the iteration for better coverage info. */
2964 {
2965 gnu_stmt
2972 gnu_stmt
2974 gnu_loop_iv);
2978 }
2979 else
2980 {
2981 gnu_stmt
2987 }
2988 }
2990 /* If the loop was named, have the name point to this loop. In this case,
2991 the association is not a DECL node, but the end label of the loop. */
2995 /* Make the loop body into its own block, so any allocated storage will be
2996 released every iteration. This is needed for stack allocation. */
3001 /* If we have an iteration scheme, then we are in a statement group. Add
3002 the LOOP_STMT to it, finish it and make it the "loop". */
3004 {
3009 /* First, if we have computed a small number of invariant conditions for
3010 range checks applied to the iteration variable, then initialize these
3011 conditions in front of the loop. Otherwise, leave them set to true.
3013 ??? The heuristics need to be improved, by taking into account the
3014 following datapoints:
3015 - loop unswitching is disabled for big loops. The cap is the
3016 parameter PARAM_MAX_UNSWITCH_INSNS (50).
3017 - loop unswitching can only be applied a small number of times
3018 to a given loop. The cap is PARAM_MAX_UNSWITCH_LEVEL (3).
3019 - the front-end quickly generates useless or redundant checks
3020 that can be entirely optimized away in the end. */
3024 i++)
3025 {
3026 tree low_ok
3033 tree high_ok
3040 tree range_ok
3048 }
3053 }
3055 /* If we have an outer COND_EXPR, that's our result and this loop is its
3056 "true" statement. Otherwise, the result is the LOOP_STMT. */
3058 {
3062 }
3063 else
3069 }
3070 \f
3071 /* This page implements a form of Named Return Value optimization modelled
3072 on the C++ optimization of the same name. The main difference is that
3073 we disregard any semantical considerations when applying it here, the
3074 counterpart being that we don't try to apply it to semantically loaded
3075 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3077 We consider a function body of the following GENERIC form:
3079 return_type R1;
3080 [...]
3081 RETURN_EXPR [<retval> = ...]
3082 [...]
3083 RETURN_EXPR [<retval> = R1]
3084 [...]
3085 return_type Ri;
3086 [...]
3087 RETURN_EXPR [<retval> = ...]
3088 [...]
3089 RETURN_EXPR [<retval> = Ri]
3090 [...]
3092 and we try to fulfill a simple criterion that would make it possible to
3093 replace one or several Ri variables with the RESULT_DECL of the function.
3095 The first observation is that RETURN_EXPRs that don't directly reference
3096 any of the Ri variables on the RHS of their assignment are transparent wrt
3097 the optimization. This is because the Ri variables aren't addressable so
3098 any transformation applied to them doesn't affect the RHS; moreover, the
3099 assignment writes the full <retval> object so existing values are entirely
3100 discarded.
3102 This property can be extended to some forms of RETURN_EXPRs that reference
3103 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3104 case, in particular when function calls are involved.
3106 Therefore the algorithm is as follows:
3108 1. Collect the list of candidates for a Named Return Value (Ri variables
3109 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3110 other expressions on the RHS of such assignments.
3112 2. Prune the members of the first list (candidates) that are referenced
3113 by a member of the second list (expressions).
3115 3. Extract a set of candidates with non-overlapping live ranges from the
3116 first list. These are the Named Return Values.
3118 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3119 Named Return Values in the function with the RESULT_DECL.
3121 If the function returns an unconstrained type, things are a bit different
3122 because the anonymous return object is allocated on the secondary stack
3123 and RESULT_DECL is only a pointer to it. Each return object can be of a
3124 different size and is allocated separately so we need not care about the
3125 aforementioned overlapping issues. Therefore, we don't collect the other
3126 expressions and skip step #2 in the algorithm. */
3128 struct nrv_data
3129 {
3130 bitmap nrv;
3131 tree result;
3132 Node_Id gnat_ret;
3134 };
3136 /* Return true if T is a Named Return Value. */
3140 {
3142 }
3144 /* Helper function for walk_tree, used by finalize_nrv below. */
3146 static tree
3148 {
3152 /* No need to walk into types or decls. */
3160 }
3162 /* Prune Named Return Values in BLOCK and return true if there is still a
3163 Named Return Value in BLOCK or one of its sub-blocks. */
3165 static bool
3167 {
3169 tree t;
3171 /* First recurse on the sub-blocks. */
3175 /* Then make sure to keep at most one NRV per block. */
3178 {
3181 else
3183 }
3186 }
3188 /* Helper function for walk_tree, used by finalize_nrv below. */
3190 static tree
3192 {
3196 /* No need to walk into types. */
3200 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3201 nop, but differs from using NULL_TREE in that it indicates that we care
3202 about the value of the RESULT_DECL. */
3205 {
3208 /* If this is the temporary created for a return value with variable
3209 size in Call_to_gnu, we replace the RHS with the init expression. */
3214 {
3217 }
3218 else
3221 /* Strip useless conversions around the return value. */
3226 {
3229 else
3231 }
3232 }
3234 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3235 if needed. */
3238 {
3242 {
3247 }
3248 else
3252 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3255 /* ??? Kludge to avoid an assertion failure during inlining. */
3258 }
3260 /* And replace all uses of NRVs with the RESULT_DECL. */
3264 /* Avoid walking into the same tree more than once. Unfortunately, we
3265 can't just use walk_tree_without_duplicates because it would only
3266 call us for the first occurrence of NRVs in the function body. */
3271 }
3273 /* Likewise, but used when the function returns an unconstrained type. */
3275 static tree
3277 {
3281 /* No need to walk into types. */
3285 /* We need to see the DECL_EXPR of NRVs before any other references so we
3286 walk the body of BIND_EXPR before walking its variables. */
3290 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3291 return value built by the allocator instead of the whole construct. */
3294 {
3297 /* This is the construct returned by the allocator. */
3300 {
3305 else
3307 }
3309 /* Strip useless conversions around the return value. */
3314 /* Strip unpadding around the return value. */
3319 /* Assign the new return value to the RESULT_DECL. */
3323 }
3325 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3326 into a new variable. */
3329 {
3336 /* Create an artificial context to build the allocation. */
3341 /* This will return a COMPOUND_EXPR with the allocation in the first
3342 arm and the final return value in the second arm. */
3349 /* The new variable is built as a reference to the allocated space. */
3350 new_var
3356 {
3359 /* The new initial value is a COMPOUND_EXPR with the allocation in
3360 the first arm and the value of P_ARRAY in the second arm. */
3366 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3373 }
3374 else
3375 {
3376 /* The new initial value is just the allocation. */
3379 }
3383 /* Destroy the artificial context and insert the new statements. */
3388 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3393 /* Save the new return value and the dereference of NEW_VAR. */
3397 /* ??? Kludge to avoid messing up during inlining. */
3399 }
3401 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3405 /* Avoid walking into the same tree more than once. Unfortunately, we
3406 can't just use walk_tree_without_duplicates because it would only
3407 call us for the first occurrence of NRVs in the function body. */
3412 }
3414 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3415 contains the candidates for Named Return Value and OTHER is a list of
3416 the other return values. GNAT_RET is a representative return node. */
3418 static void
3420 {
3423 walk_tree_fn func;
3425 tree iter;
3427 /* We shouldn't be applying the optimization to return types that we aren't
3428 allowed to manipulate freely. */
3431 /* Prune the candidates that are referenced by other return values. */
3440 /* Prune also the candidates that are referenced by nested functions. */
3448 /* Extract a set of NRVs with non-overlapping live ranges. */
3452 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3459 else
3463 }
3465 /* Return true if RET_VAL can be used as a Named Return Value for the
3466 anonymous return object RET_OBJ. */
3468 static bool
3470 {
3490 }
3492 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3493 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3494 around RESULT_OBJ, which may be null in this case. */
3496 static tree
3498 {
3499 tree result_expr;
3502 {
3503 /* The gimplifier explicitly enforces the following invariant:
3505 RETURN_EXPR
3506 |
3507 INIT_EXPR
3508 / \
3509 / \
3510 RET_OBJ ...
3512 As a consequence, type consistency dictates that we use the type
3513 of the RET_OBJ as the operation type. */
3516 /* Convert the right operand to the operation type. Note that this is
3517 the transformation applied in the INIT_EXPR case of build_binary_op,
3518 with the assumption that the type cannot involve a placeholder. */
3522 /* We always can use an INIT_EXPR for the return object. */
3525 /* If the function returns an aggregate type, find out whether this is
3526 a candidate for Named Return Value. If so, record it. Otherwise,
3527 if this is an expression of some kind, record it elsewhere. */
3533 {
3534 /* Recognize the temporary created for a return value with variable
3535 size in Call_to_gnu. We want to eliminate it if possible. */
3542 /* Strip useless conversions around the return value. */
3546 /* Now apply the test to the return value. */
3548 {
3552 }
3554 /* Note that we need not care about CONSTRUCTORs here, as they are
3555 totally transparent given the read-compose-write semantics of
3556 assignments from CONSTRUCTORs. */
3559 }
3560 }
3561 else
3565 }
3566 \f
3567 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3568 don't return anything. */
3570 static void
3572 {
3573 /* Defining identifier of a parameter to the subprogram. */
3574 Entity_Id gnat_param;
3575 /* The defining identifier for the subprogram body. Note that if a
3576 specification has appeared before for this body, then the identifier
3577 occurring in that specification will also be a defining identifier and all
3578 the calls to this subprogram will point to that specification. */
3579 Entity_Id gnat_subprog_id
3582 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3583 tree gnu_subprog_decl;
3584 /* Its RESULT_DECL node. */
3585 tree gnu_result_decl;
3586 /* Its FUNCTION_TYPE node. */
3587 tree gnu_subprog_type;
3588 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3589 tree gnu_cico_list;
3590 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3592 tree gnu_result;
3593 location_t locus;
3597 /* If this is a generic object or if it has been eliminated,
3598 ignore it. */
3604 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3605 the already-elaborated tree node. However, if this subprogram had its
3606 elaboration deferred, we will already have made a tree node for it. So
3607 treat it as not being defined in that case. Such a subprogram cannot
3608 have an address clause or a freeze node, so this test is safe, though it
3609 does disable some otherwise-useful error checking. */
3610 gnu_subprog_decl
3620 /* If the function returns by invisible reference, make it explicit in the
3621 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3623 {
3627 }
3629 /* Set the line number in the decl to correspond to that of the body. */
3633 /* Initialize the information structure for the function. */
3642 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3643 properly copied out by the return statement. We do this by making a new
3644 block and converting any return into a goto to a label at the end of the
3645 block. */
3647 {
3656 /* If this is a function with copy-in/copy-out parameters and which does
3657 not return by invisible reference, we also need a variable for the
3658 return value to be placed. */
3660 {
3661 tree gnu_return_type
3664 gnu_return_var
3669 }
3673 /* See whether there are parameters for which we don't have a GCC tree
3674 yet. These must be Out parameters. Make a VAR_DECL for them and
3675 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3676 We can match up the entries because TYPE_CI_CO_LIST is in the order
3677 of the parameters. */
3682 {
3684 tree gnu_decl;
3686 /* Skip any entries that have been already filled in; they must
3687 correspond to In Out parameters. */
3691 /* Do any needed dereferences for by-ref objects. */
3697 /* Do any needed references for padded types. */
3700 }
3701 }
3702 else
3705 /* Get a tree corresponding to the code for the subprogram. */
3711 /* Generate the code of the subprogram itself. A return statement will be
3712 present and any Out parameters will be handled there. */
3717 /* If we populated the parameter attributes cache, we need to make sure that
3718 the cached expressions are evaluated on all the possible paths leading to
3719 their uses. So we force their evaluation on entry of the function. */
3722 {
3729 {
3736 }
3742 }
3744 /* If we are dealing with a return from an Ada procedure with parameters
3745 passed by copy-in/copy-out, we need to return a record containing the
3746 final values of these parameters. If the list contains only one entry,
3747 return just that entry though.
3749 For a full description of the copy-in/copy-out parameter mechanism, see
3750 the part of the gnat_to_gnu_entity routine dealing with the translation
3751 of subprograms.
3753 We need to make a block that contains the definition of that label and
3754 the copying of the return value. It first contains the function, then
3755 the label and copy statement. */
3757 {
3758 const Node_Id gnat_end_label
3767 /* If this is a function which returns by invisible reference, the
3768 return value has already been dealt with at the return statements,
3769 so we only need to indirectly copy out the parameters. */
3771 {
3772 tree gnu_ret_deref
3774 tree t;
3779 {
3780 tree gnu_field_deref
3786 }
3787 }
3789 /* Otherwise, if this is a procedure or a function which does not return
3790 by invisible reference, we can do a direct block-copy out. */
3791 else
3792 {
3793 tree gnu_retval;
3797 else
3798 gnu_retval
3800 gnu_cico_list);
3804 }
3808 }
3812 /* Attempt setting the end_locus of our GCC body tree, typically a
3813 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3814 declaration tree. */
3818 /* On SEH targets, install an exception handler around the main entry
3819 point to catch unhandled exceptions. */
3822 {
3823 tree t;
3824 tree etype;
3836 }
3840 /* Finally annotate the parameters and disconnect the trees for parameters
3841 that we have turned into variables since they are now unusable. */
3845 {
3854 }
3856 /* Disconnect the variable created for the return value. */
3860 /* If the function returns an aggregate type and we have candidates for
3861 a Named Return Value, finalize the optimization. */
3863 {
3870 }
3872 /* If this is an inlined external function that has been marked uninlinable,
3873 drop the body and stop there. Otherwise compile the body. */
3876 else
3878 }
3879 \f
3880 /* Return true if GNAT_NODE references an Atomic entity. */
3882 static bool
3884 {
3885 Entity_Id gnat_entity;
3888 {
3904 /* ... fall through ... */
3911 }
3914 }
3916 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. */
3918 static bool
3920 {
3921 Entity_Id gnat_entity;
3924 {
3944 }
3947 }
3949 /* Strip any type conversion on GNAT_NODE and return the result. */
3951 static Node_Id
3953 {
3960 }
3962 /* Return true if GNAT_NODE requires outer atomic access, i.e. atomic access
3963 of an object of which GNAT_NODE is a component. */
3965 static bool
3967 {
3971 {
3973 {
3978 gnat_node
3992 }
3993 }
3996 }
3998 /* Return true if GNAT_NODE requires atomic access and set SYNC according to
3999 the associated synchronization setting. */
4001 static bool
4003 {
4008 /* First, scan the parent to find out cases where the flag is irrelevant. */
4010 {
4013 /* Do not mess up machine code insertions. */
4017 /* Nothing to do if we are the prefix of an attribute, since we do not
4018 want an atomic access for things like 'Size. */
4020 /* ... fall through ... */
4023 /* The N_Reference node is like an attribute. */
4031 /* If we are the prefix, then the access is only partial. */
4037 /* Nothing to do for the identifier in an object renaming declaration,
4038 the renaming itself does not need atomic access. */
4043 }
4045 /* Then, scan the node to find the atomic object. */
4048 /* For Atomic itself, only reads and updates of the object as a whole require
4049 atomic access (RM C.6 (15)). But for Volatile_Full_Access, all reads and
4050 updates require atomic access. */
4055 /* If an outer atomic access will also be required, it cancels this one. */
4062 }
4063 \f
4064 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4066 static tree
4068 {
4076 }
4078 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4079 Put the initialization statement into GNU_INIT_STMT and annotate it with
4080 the SLOC of GNAT_NODE. Return the temporary variable. */
4082 static tree
4084 Node_Id gnat_node)
4085 {
4092 }
4094 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
4095 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4096 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4097 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4098 N_Assignment_Statement and the result is to be placed into that object.
4099 If OUTER_ATOMIC_ACCESS is true, then the assignment to GNU_TARGET must be a
4100 load-modify-store sequence. Otherwise, if ATOMIC_ACCESS is true, then the
4101 assignment to GNU_TARGET must be atomic. If, in addition, ATOMIC_SYNC is
4102 true, then the assignment to GNU_TARGET requires atomic synchronization. */
4104 static tree
4107 {
4110 /* The GCC node corresponding to the GNAT subprogram name. This can either
4111 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4112 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4113 subprogram. */
4115 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4117 /* The return type of the FUNCTION_TYPE. */
4128 Entity_Id gnat_formal;
4129 Node_Id gnat_actual;
4134 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4135 all our args first. */
4137 {
4147 {
4150 }
4153 }
4155 /* For a call to a nested function, check the inlining status. */
4160 /* The only way we can be making a call via an access type is if Name is an
4161 explicit dereference. In that case, get the list of formal args from the
4162 type the access type is pointing to. Otherwise, get the formals from the
4163 entity being called. */
4167 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4169 else
4172 /* The lifetime of the temporaries created for the call ends right after the
4173 return value is copied, so we can give them the scope of the elaboration
4174 routine at top level. */
4176 {
4179 }
4181 /* First, create the temporary for the return value when:
4183 1. There is no target and the function has copy-in/copy-out parameters,
4184 because we need to preserve the return value before copying back the
4185 parameters.
4187 2. There is no target and this is neither an object nor a renaming
4188 declaration, and the return type has variable size, because in
4189 these cases the gimplifier cannot create the temporary.
4191 3. There is a target and it is a slice or an array with fixed size,
4192 and the return type has variable size, because the gimplifier
4193 doesn't handle these cases.
4195 This must be done before we push a binding level around the call, since
4196 we will pop it before copying the return value. */
4199 || (!gnu_target
4203 || (gnu_target
4211 /* Create the list of the actual parameters as GCC expects it, namely a
4212 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4213 is an expression and the TREE_PURPOSE field is null. But skip Out
4214 parameters not passed by reference and that need not be copied in. */
4219 {
4224 const bool is_true_formal_parm
4226 const bool is_by_ref_formal_parm
4227 = is_true_formal_parm
4230 /* In the Out or In Out case, we must suppress conversions that yield
4231 an lvalue but can nevertheless cause the creation of a temporary,
4232 because we need the real object in this case, either to pass its
4233 address if it's passed by reference or as target of the back copy
4234 done after the call if it uses the copy-in/copy-out mechanism.
4235 We do it in the In case too, except for an unchecked conversion
4236 to an elementary type or a constrained composite type because it
4237 alone can cause the actual to be misaligned and the addressability
4238 test is applied to the real object. */
4239 const bool suppress_type_conversion
4246 Node_Id gnat_name = suppress_type_conversion
4249 tree gnu_actual;
4251 /* If it's possible we may need to use this expression twice, make sure
4252 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4253 to force side-effects before the call. */
4255 && !is_by_ref_formal_parm
4257 {
4261 gnu_name
4263 }
4265 /* If we are passing a non-addressable parameter by reference, pass the
4266 address of a copy. In the Out or In Out case, set up to copy back
4267 out after the call. */
4271 {
4275 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4276 but sort of an instantiation for them. */
4278 ;
4280 /* If the type is passed by reference, a copy is not allowed. */
4283 gnat_actual);
4285 /* For users of Starlet we issue a warning because the interface
4286 apparently assumes that by-ref parameters outlive the procedure
4287 invocation. The code still will not work as intended, but we
4288 cannot do much better since low-level parts of the back-end
4289 would allocate temporaries at will because of the misalignment
4290 if we did not do so here. */
4292 {
4293 post_error
4295 post_error_ne
4299 gnat_formal);
4300 }
4302 /* If the actual type of the object is already the nominal type,
4303 we have nothing to do, except if the size is self-referential
4304 in which case we'll remove the unpadding below. */
4307 ;
4309 /* Otherwise remove the unpadding from all the objects. */
4311 && TYPE_IS_PADDING_P
4315 /* Otherwise convert to the nominal type of the object if needed.
4316 There are several cases in which we need to make the temporary
4317 using this type instead of the actual type of the object when
4318 they are distinct, because the expectations of the callee would
4319 otherwise not be met:
4320 - if it's a justified modular type,
4321 - if the actual type is a smaller form of it,
4322 - if it's a smaller form of the actual type. */
4326 gnu_name_type)))
4332 /* If this is an In Out or Out parameter and we're returning a value,
4333 we need to create a temporary for the return value because we must
4334 preserve it before copying back at the very end. */
4338 /* If we haven't pushed a binding level, push a new one. This will
4339 narrow the lifetime of the temporary we are about to make as much
4340 as possible. The drawback is that we'd need to create a temporary
4341 for the return value, if any (see comment before the loop). So do
4342 it only when this temporary was already created just above. */
4344 {
4348 }
4350 /* Create an explicit temporary holding the copy. */
4351 gnu_temp
4354 /* But initialize it on the fly like for an implicit temporary as
4355 we aren't necessarily having a statement list. */
4357 gnu_temp);
4359 /* Set up to move the copy back to the original if needed. */
4361 {
4362 /* If the original is a COND_EXPR whose first arm isn't meant to
4363 be further used, just deal with the second arm. This is very
4364 likely the conditional expression built for a check. */
4367 && integer_zerop
4371 gnu_stmt
4376 }
4377 }
4379 /* Start from the real object and build the actual. */
4382 /* If atomic access is required for an In or In Out actual parameter,
4383 build the atomic load. */
4385 && !is_by_ref_formal_parm
4390 /* If this was a procedure call, we may not have removed any padding.
4391 So do it here for the part we will use as an input, if any. */
4394 gnu_actual
4397 /* Put back the conversion we suppressed above in the computation of the
4398 real object. And even if we didn't suppress any conversion there, we
4399 may have suppressed a conversion to the Etype of the actual earlier,
4400 since the parent is a procedure call, so put it back here. */
4403 gnu_actual
4406 else
4407 gnu_actual
4410 /* Make sure that the actual is in range of the formal's type. */
4413 gnu_actual
4416 /* Unless this is an In parameter, we must remove any justified modular
4417 building from GNU_NAME to get an lvalue. */
4422 gnu_name
4425 /* First see if the parameter is passed by reference. */
4427 {
4429 {
4430 /* In Out or Out parameters passed by reference don't use the
4431 copy-in/copy-out mechanism so the address of the real object
4432 must be passed to the function. */
4435 /* If we have a padded type, be sure we've removed padding. */
4438 gnu_actual);
4440 /* If we have the constructed subtype of an aliased object
4441 with an unconstrained nominal subtype, the type of the
4442 actual includes the template, although it is formally
4443 constrained. So we need to convert it back to the real
4444 constructed subtype to retrieve the constrained part
4445 and takes its address. */
4451 gnu_actual);
4452 }
4454 /* There is no need to convert the actual to the formal's type before
4455 taking its address. The only exception is for unconstrained array
4456 types because of the way we build fat pointers. */
4458 {
4459 /* Put back a view conversion for In Out or Out parameters. */
4462 gnu_actual);
4464 }
4466 /* The symmetry of the paths to the type of an entity is broken here
4467 since arguments don't know that they will be passed by ref. */
4470 }
4472 /* Then see if the parameter is an array passed to a foreign convention
4473 subprogram. */
4475 {
4481 {
4484 }
4486 /* Take the address of the object and convert to the proper pointer
4487 type. We'd like to actually compute the address of the beginning
4488 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4489 possibility that the ARRAY_REF might return a constant and we'd be
4490 getting the wrong address. Neither approach is exactly correct,
4491 but this is the most likely to work in all cases. */
4493 }
4495 /* Otherwise the parameter is passed by copy. */
4496 else
4497 {
4498 tree gnu_size;
4503 /* If we didn't create a PARM_DECL for the formal, this means that
4504 it is an Out parameter not passed by reference and that need not
4505 be copied in. In this case, the value of the actual need not be
4506 read. However, we still need to make sure that its side-effects
4507 are evaluated before the call, so we evaluate its address. */
4509 {
4511 {
4514 }
4516 }
4520 /* If this is 'Null_Parameter, pass a zero even though we are
4521 dereferencing it. */
4527 gnu_actual
4531 integer_zero_node),
4533 else
4535 }
4538 }
4540 gnu_call
4544 /* If we have created a temporary for the return value, initialize it. */
4546 {
4547 tree gnu_stmt
4552 }
4554 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4555 unpack the valued returned from the function into the In Out or Out
4556 parameters. We deal with the function return (if this is an Ada
4557 function) below. */
4559 {
4560 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4561 copy-out parameters. */
4565 /* The call sequence must contain one and only one call, even though the
4566 function is pure. Save the result into a temporary if needed. */
4568 {
4570 {
4571 tree gnu_stmt;
4572 /* If we haven't pushed a binding level, push a new one. This
4573 will narrow the lifetime of the temporary we are about to
4574 make as much as possible. */
4576 {
4580 }
4581 gnu_call
4584 }
4587 }
4589 /* The first entry is for the actual return value if this is a
4590 function, so skip it. */
4596 else
4603 /* If we are dealing with a copy-in/copy-out parameter, we must
4604 retrieve its value from the record returned in the call. */
4610 {
4611 /* Get the value to assign to this Out or In Out parameter. It is
4612 either the result of the function if there is only a single such
4613 parameter or the appropriate field from the record returned. */
4614 tree gnu_result
4616 ? gnu_call
4620 /* If the actual is a conversion, get the inner expression, which
4621 will be the real destination, and convert the result to the
4622 type of the actual parameter. */
4623 tree gnu_actual
4626 /* If the result is a padded type, remove the padding. */
4628 gnu_result
4630 gnu_result);
4632 /* If the actual is a type conversion, the real target object is
4633 denoted by the inner Expression and we need to convert the
4634 result to the associated type.
4635 We also need to convert our gnu assignment target to this type
4636 if the corresponding GNU_NAME was constructed from the GNAT
4637 conversion node and not from the inner Expression. */
4639 {
4640 gnu_result
4641 = convert_with_check
4649 }
4651 /* Unchecked conversions as actuals for Out parameters are not
4652 allowed in user code because they are not variables, but do
4653 occur in front-end expansions. The associated GNU_NAME is
4654 always obtained from the inner expression in such cases. */
4657 gnu_result,
4659 else
4660 {
4662 gnu_result
4664 gnat_actual);
4669 }
4671 /* If an outer atomic access is required for an actual parameter,
4672 build the load-modify-store sequence. */
4674 gnu_result
4677 /* Or else, if simple atomic access is required, build the atomic
4678 store. */
4682 /* Otherwise build a regular assignment. */
4683 else
4692 }
4693 }
4695 /* If this is a function call, the result is the call expression unless a
4696 target is specified, in which case we copy the result into the target
4697 and return the assignment statement. */
4699 {
4700 /* If this is a function with copy-in/copy-out parameters, extract the
4701 return value from it and update the return type. */
4703 {
4708 }
4710 /* If the function returns an unconstrained array or by direct reference,
4711 we have to dereference the pointer. */
4717 {
4721 /* If range check is needed, emit code to generate it. */
4723 gnu_call
4725 gnat_parent);
4727 /* ??? If the return type has variable size, then force the return
4728 slot optimization as we would not be able to create a temporary.
4729 That's what has been done historically. */
4732 else
4735 /* Use the required method to move the result to the target. */
4737 gnu_call
4741 else
4742 gnu_call
4748 }
4749 else
4751 }
4753 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4754 parameters, the result is just the call statement. */
4758 /* Finally, add the copy back statements, if any. */
4764 /* If we have pushed a binding level, pop it and finish up the enclosing
4765 statement group. */
4767 {
4771 }
4773 /* Otherwise, retrieve the statement list, if any. */
4777 /* Otherwise, just return the call expression. */
4778 else
4781 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4782 But first simplify if we have only one statement in the list. */
4784 {
4788 gnu_result
4790 }
4793 }
4794 \f
4795 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4796 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4798 static tree
4800 {
4803 /* If just annotating, ignore all EH and cleanups. */
4807 bool setjmp_longjmp
4813 tree gnu_result;
4814 tree gnu_expr;
4815 Node_Id gnat_temp;
4816 /* Node providing the sloc for the cleanup actions. */
4819 gnat_node);
4821 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4822 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4823 add_cleanup, and when we leave the binding, end_stmt_group will create
4824 the TRY_FINALLY_EXPR.
4826 ??? The region level calls down there have been specifically put in place
4827 for a ZCX context and currently the order in which things are emitted
4828 (region/handlers) is different from the SJLJ case. Instead of putting
4829 other calls with different conditions at other places for the SJLJ case,
4830 it seems cleaner to reorder things for the SJLJ case and generalize the
4831 condition to make it not ZCX specific.
4833 If there are any exceptions or cleanup processing involved, we need an
4834 outer statement group (for Setjmp_Longjmp) and binding level. */
4836 {
4839 }
4841 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
4842 area for address of previous buffer. Do this first since we need to have
4843 the setjmp buf known for any decls in this block. */
4845 {
4846 gnu_jmpsave_decl
4848 jmpbuf_ptr_type,
4853 /* The __builtin_setjmp receivers will immediately reinstall it. Now
4854 because of the unstructured form of EH used by setjmp_longjmp, there
4855 might be forward edges going to __builtin_setjmp receivers on which
4856 it is uninitialized, although they will never be actually taken. */
4858 gnu_jmpbuf_decl
4860 jmpbuf_type,
4861 NULL_TREE,
4867 /* When we exit this block, restore the saved value. */
4869 gnat_cleanup_loc_node);
4870 }
4872 /* If we are to call a function when exiting this block, add a cleanup
4873 to the binding level we made above. Note that add_cleanup is FIFO
4874 so we must register this cleanup after the EH cleanup just above. */
4877 gnat_cleanup_loc_node);
4879 /* Now build the tree for the declarations and statements inside this block.
4880 If this is SJLJ, set our jmp_buf as the current buffer. */
4884 {
4887 gnu_jmpbuf_decl));
4890 }
4896 /* Generate code for each statement in the block. */
4904 /* Now generate code for the two exception models, if either is relevant for
4905 this block. */
4907 {
4909 tree gnu_handler;
4911 /* Make a binding level for the exception handling declarations and code
4912 and set up gnu_except_ptr_stack for the handlers to use. */
4923 /* Generate code for each handler. The N_Exception_Handler case does the
4924 real work and returns a COND_EXPR for each handler, which we chain
4925 together here. */
4928 {
4931 /* If this is the first one, set it as the outer one. Otherwise,
4932 point the "else" part of the previous handler to us. Then point
4933 to our "else" part. */
4936 else
4940 }
4942 /* If none of the exception handlers did anything, re-raise but do not
4943 defer abortion. */
4946 set_expr_location_from_node
4952 else
4955 /* End the binding level dedicated to the exception handlers and get the
4956 whole statement group. */
4961 /* If the setjmp returns 1, we restore our incoming longjmp value and
4962 then check the handlers. */
4965 gnu_jmpsave_decl),
4966 gnat_node);
4970 /* This block is now "if (setjmp) ... <handlers> else <block>". */
4972 (build_call_n_expr
4975 gnu_jmpbuf_decl))),
4977 }
4979 {
4980 tree gnu_handlers;
4981 location_t locus;
4983 /* First make a block containing the handlers. */
4991 /* Now make the TRY_CATCH_EXPR for the block. */
4994 /* Set a location. We need to find a unique location for the dispatching
4995 code, otherwise we can get coverage or debugging issues. Try with
4996 the location of the end label. */
5000 else
5001 /* Clear column information so that the exception handler of an
5002 implicit transient block does not incorrectly inherit the slocs
5003 of a decision, which would otherwise confuse control flow based
5004 coverage analysis tools. */
5006 }
5007 else
5010 /* Now close our outer block, if we had to make one. */
5012 {
5016 }
5019 }
5020 \f
5021 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5022 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
5023 exception handling. */
5025 static tree
5027 {
5028 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
5029 an "if" statement to select the proper exceptions. For "Others", exclude
5030 exceptions where Handled_By_Others is nonzero unless the All_Others flag
5031 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
5034 Node_Id gnat_temp;
5038 {
5039 tree this_choice;
5042 {
5045 else
5046 this_choice
5047 = build_binary_op
5049 convert
5051 build_component_ref
5052 (build_unary_op
5057 integer_zero_node);
5058 }
5062 {
5064 tree gnu_expr;
5066 /* Exception may be a renaming. Recover original exception which is
5067 the one elaborated and registered. */
5073 this_choice
5074 = build_binary_op
5079 }
5080 else
5085 }
5088 }
5089 \f
5090 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5091 to a GCC tree, which is returned. This is the variant for ZCX. */
5093 static tree
5095 {
5098 Node_Id gnat_temp;
5100 /* We build a TREE_LIST of nodes representing what exception types this
5101 handler can catch, with special cases for others and all others cases.
5103 Each exception type is actually identified by a pointer to the exception
5104 id, or to a dummy object for "others" and "all others". */
5107 {
5111 {
5114 }
5117 {
5120 /* Exception may be a renaming. Recover original exception which is
5121 the one elaborated and registered. */
5127 }
5128 else
5131 /* The GCC interface expects NULL to be passed for catch all handlers, so
5132 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5133 is integer_zero_node. It would not work, however, because GCC's
5134 notion of "catch all" is stronger than our notion of "others". Until
5135 we correctly use the cleanup interface as well, doing that would
5136 prevent the "all others" handlers from being seen, because nothing
5137 can be caught beyond a catch all from GCC's point of view. */
5139 }
5144 /* Expand a call to the begin_handler hook at the beginning of the handler,
5145 and arrange for a call to the end_handler hook to occur on every possible
5146 exit path.
5148 The hooks expect a pointer to the low level occurrence. This is required
5149 for our stack management scheme because a raise inside the handler pushes
5150 a new occurrence on top of the stack, which means that this top does not
5151 necessarily match the occurrence this handler was dealing with.
5153 __builtin_eh_pointer references the exception occurrence being
5154 propagated. Upon handler entry, this is the exception for which the
5155 handler is triggered. This might not be the case upon handler exit,
5156 however, as we might have a new occurrence propagated by the handler's
5157 body, and the end_handler hook called as a cleanup in this context.
5159 We use a local variable to retrieve the incoming value at handler entry
5160 time, and reuse it to feed the end_handler hook's argument at exit. */
5162 gnu_current_exc_ptr
5172 gnu_incoming_exc_ptr),
5173 gnat_node);
5175 /* Declare and initialize the choice parameter, if present. */
5177 {
5178 tree gnu_param
5184 gnu_incoming_exc_ptr));
5185 }
5187 /* We don't have an End_Label at hand to set the location of the cleanup
5188 actions, so we use that of the exception handler itself instead. */
5190 gnat_node);
5196 return
5198 }
5199 \f
5200 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5202 static void
5204 {
5209 Entity_Id gnat_entity;
5210 Node_Id gnat_pragma;
5211 /* Make the decl for the elaboration procedure. */
5212 tree gnu_elab_proc_decl
5213 = create_subprog_decl
5216 gnat_unit);
5222 /* Initialize the information structure for the function. */
5231 /* For a body, first process the spec if there is one. */
5237 {
5244 }
5246 /* Then process any pragmas and declarations preceding the unit. */
5255 /* Process the unit itself. */
5258 /* Generate code for all the inlined subprograms. */
5262 {
5263 Node_Id gnat_body;
5265 /* Without optimization, process only the required subprograms. */
5271 {
5272 /* ??? This happens when only the spec of a package is provided. */
5276 gnat_body
5278 }
5280 /* Define the entity first so we set DECL_EXTERNAL. */
5283 }
5285 /* Process any pragmas and actions following the unit. */
5290 /* Save away what we've made so far and finish it up. */
5297 /* Record this potential elaboration procedure for later processing. */
5304 /* Force the processing for all nodes that remain in the queue. */
5306 }
5307 \f
5308 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5309 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5310 we should place the result type. LABEL_P is true if there is a label to
5311 branch to for the exception. */
5313 static tree
5315 {
5319 const bool with_extra_info
5320 = Exception_Extra_Info
5328 {
5338 {
5344 {
5364 }
5371 && gnu_low_bound
5372 && gnu_high_bound
5375 gnu_result
5379 /* If loop unswitching is enabled, we try to compute invariant
5380 conditions for checks applied to iteration variables, i.e.
5381 conditions that are both independent of the variable and
5382 necessary in order for the check to fail in the course of
5383 some iteration, and prepend them to the original condition
5384 of the checks. This will make it possible later for the
5385 loop unswitching pass to replace the loop with two loops,
5386 one of which has the checks eliminated and the other has
5387 the original checks reinstated, and a run time selection.
5388 The former loop will be suitable for vectorization. */
5391 && (!gnu_low_bound
5393 && (!gnu_high_bound
5396 {
5401 boolean_true_node);
5403 boolean_type_node,
5406 }
5407 }
5412 }
5414 common:
5419 /* If the type is VOID, this is a statement, so we need to generate the code
5420 for the call. Handle a condition, if there is one. */
5422 {
5424 {
5429 }
5430 }
5431 else
5435 }
5436 \f
5437 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5438 parameter of a call. */
5440 static bool
5442 {
5457 }
5459 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5460 of an assignment or an actual parameter of a call. */
5462 static bool
5464 {
5465 Node_Kind kind;
5477 }
5479 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5480 as gigi is concerned. This is used to avoid conversions on the LHS. */
5482 static bool
5484 {
5487 /* The conversion must be on the LHS of an assignment or an actual parameter
5488 of a call. Otherwise, even if the conversion was essentially a no-op, it
5489 could de facto ensure type consistency and this should be preserved. */
5495 /* We're interested in artificial conversions generated by the front-end
5496 to make private types explicit, e.g. in Expand_Assign_Array. */
5503 /* The direct conversion to the underlying type is a no-op. */
5507 /* For an array subtype, the conversion to the PAIT is a no-op. */
5512 /* For a record subtype, the conversion to the type is a no-op. */
5518 }
5520 /* This function is the driver of the GNAT to GCC tree transformation process.
5521 It is the entry point of the tree transformer. GNAT_NODE is the root of
5522 some GNAT tree. Return the root of the corresponding GCC tree. If this
5523 is an expression, return the GCC equivalent of the expression. If this
5524 is a statement, return the statement or add it to the current statement
5525 group, in which case anything returned is to be interpreted as occurring
5526 after anything added. */
5528 tree
5530 {
5536 Node_Id gnat_temp;
5539 /* Save node number for error message and set location information. */
5543 /* If this node is a statement and we are only annotating types, return an
5544 empty statement list. */
5548 /* If this node is a non-static subexpression and we are only annotating
5549 types, make this into a NULL_EXPR. */
5556 N_Raise_Constraint_Error));
5565 {
5568 /* If this is a statement and we are at top level, it must be part of
5569 the elaboration procedure, so mark us as being in that procedure. */
5571 {
5574 }
5576 /* If we are in the elaboration procedure, check if we are violating a
5577 No_Elaboration_Code restriction by having a statement there. Don't
5578 check for a possible No_Elaboration_Code restriction violation on
5579 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5580 every nested real statement instead. This also avoids triggering
5581 spurious errors on dummy (empty) sequences created by the front-end
5582 for package bodies in some cases. */
5586 }
5589 {
5590 /********************************/
5591 /* Chapter 2: Lexical Elements */
5592 /********************************/
5600 /* If atomic access is required on the RHS, build the atomic load. */
5607 {
5608 tree gnu_type;
5610 /* Get the type of the result, looking inside any padding and
5611 justified modular types. Then get the value in that type. */
5620 /* If the result overflows (meaning it doesn't fit in its base type),
5621 abort. We would like to check that the value is within the range
5622 of the subtype, but that causes problems with subtypes whose usage
5623 will raise Constraint_Error and with biased representation, so
5624 we don't. */
5626 }
5630 /* If a Entity is present, it means that this was one of the
5631 literals in a user-defined character type. In that case,
5632 just return the value in the CONST_DECL. Otherwise, use the
5633 character code. In that case, the base type should be an
5634 INTEGER_TYPE, but we won't bother checking for that. */
5638 else
5639 gnu_result
5640 = build_int_cst_type
5647 /* If this is of a fixed-point type, the value we want is the value of
5648 the corresponding integer. */
5650 {
5652 gnu_result_type);
5654 }
5656 else
5657 {
5660 /* First convert the value to a machine number if it isn't already.
5661 That will force the base to 2 for non-zero values and simplify
5662 the rest of the logic. */
5664 ur_realval
5670 else
5671 {
5672 REAL_VALUE_TYPE tmp;
5676 /* The base must be 2 as Machine guarantees this, so we scale
5677 the value, which we know can fit in the mantissa of the type
5678 (hence the use of that type above). */
5683 }
5685 /* Now see if we need to negate the result. Do it this way to
5686 properly handle -0. */
5688 gnu_result
5690 gnu_result);
5691 }
5698 {
5705 else
5708 /* Build the string with the characters in the literal. Note
5709 that Ada strings are 1-origin. */
5713 /* Put a null at the end of the string in case it's in a context
5714 where GCC will want to treat it as a C string. */
5719 /* Strings in GCC don't normally have types, but we want
5720 this to not be converted to the array type. */
5725 }
5726 else
5727 {
5728 /* Build a list consisting of each character, then make
5729 the aggregate. */
5739 {
5745 }
5748 }
5755 /**************************************/
5756 /* Chapter 3: Declarations and Types */
5757 /**************************************/
5774 /* If we are just annotating types and this object has an unconstrained
5775 or task type, don't elaborate it. */
5785 && (!type_annotate_only
5787 {
5790 gnu_expr
5795 }
5796 else
5799 /* If this is a deferred constant with an address clause, we ignore the
5800 full view since the clause is on the partial view and we cannot have
5801 2 different GCC trees for the object. The only bits of the full view
5802 we will use is the initializer, but it will be directly fetched. */
5808 /* If this object has its elaboration delayed, we must force evaluation
5809 of GNU_EXPR now and save it for the freeze point. Note that we need
5810 not do anything special at the global level since the lifetime of the
5811 temporary is fully contained within the elaboration routine. */
5813 {
5815 {
5818 }
5819 }
5820 else
5828 /* Don't do anything if this renaming is handled by the front end or if
5829 we are just annotating types and this object has a composite or task
5830 type, don't elaborate it. */
5832 && ! (type_annotate_only
5836 {
5837 tree gnu_temp
5840 /* See case 2 of renaming in gnat_to_gnu_entity. */
5843 }
5850 /* See the above case for the rationale. */
5852 {
5853 tree gnu_temp
5858 }
5869 /* These are fully handled in the front end. */
5870 /* ??? For package renamings, find a way to use GENERIC namespaces so
5871 that we get proper debug information for them. */
5875 /*************************************/
5876 /* Chapter 4: Names and Expressions */
5877 /*************************************/
5884 /* If atomic access is required on the RHS, build the atomic load. */
5891 {
5893 tree gnu_type;
5900 /* Convert vector inputs to their representative array type, to fit
5901 what the code below expects. */
5903 {
5907 }
5911 /* If we got a padded type, remove it too. */
5913 gnu_array_object
5915 gnu_array_object);
5919 /* The failure of this assertion will very likely come from a missing
5920 expansion for a packed array access. */
5923 /* First compute the number of dimensions of the array, then
5924 fill the expression array, the order depending on whether
5925 this is a Convention_Fortran array or not. */
5930 ;
5939 else
5947 {
5953 gnu_expr
5954 = emit_index_check
5958 gnat_temp);
5960 gnu_result
5963 /* Array accesses are bound-checked so they cannot trap, but this
5964 is valid only if they are not hoisted ahead of the check. We
5965 need to mark them as no-trap to get decent loop optimizations
5966 in the presence of -fnon-call-exceptions, so we do it when we
5967 know that the original expression had no side-effects. */
5972 }
5976 /* If atomic access is required on the RHS, build the atomic load. */
5980 }
5984 {
5986 tree gnu_type;
5991 /* Do any implicit dereferences of the prefix and do any needed
5992 range check. */
5997 {
5998 /* Get the bounds of the slice. */
5999 tree gnu_index_type
6003 /* Get the permitted bounds. */
6004 tree gnu_base_index_type
6006 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
6008 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
6015 /* Derive a good type to convert everything to. */
6018 /* Test whether the minimum slice value is too small. */
6021 gnu_min_expr),
6023 gnu_base_min_expr));
6025 /* Test whether the maximum slice value is too large. */
6028 gnu_max_expr),
6030 gnu_base_max_expr));
6032 /* Build a slice index check that returns the low bound,
6033 assuming the slice is not empty. */
6034 gnu_expr = emit_check
6039 /* Build a conditional expression that does the index checks and
6040 returns the low bound if the slice is not empty (max >= min),
6041 and returns the naked low bound otherwise (max < min), unless
6042 it is non-constant and the high bound is; this prevents VRP
6043 from inferring bogus ranges on the unlikely path. */
6047 gnu_max_expr),
6049 gnu_min_expr)),
6050 gnu_expr,
6054 }
6055 else
6056 /* Simply return the naked low bound. */
6059 /* If this is a slice with non-constant size of an array with constant
6060 size, set the maximum size for the allocation of temporaries. */
6067 }
6071 {
6075 tree gnu_field;
6079 /* For discriminant references in tagged types always substitute the
6080 corresponding discriminant as the actual selected component. */
6085 /* For discriminant references of untagged types always substitute the
6086 corresponding stored discriminant. */
6090 /* Handle extracting the real or imaginary part of a complex.
6091 The real part is the first field and the imaginary the last. */
6096 else
6097 {
6100 gnu_result
6104 && lvalue_required_for_attribute_p
6106 }
6110 /* If atomic access is required on the RHS, build the atomic load. */
6114 }
6118 {
6119 /* The attribute designator. */
6122 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6123 is a unit, not an object with a GCC equivalent. */
6125 return
6133 }
6137 /* Like 'Access as far as we are concerned. */
6145 {
6146 tree gnu_aggr_type;
6148 /* ??? It is wrong to evaluate the type now, but there doesn't
6149 seem to be any other practical way of doing it. */
6153 gnu_aggr_type = gnu_result_type
6158 gnu_aggr_type
6165 NULL);
6169 gnu_result
6172 gnu_aggr_type);
6175 gnu_aggr_type,
6178 gnu_result
6179 = build_binary_op
6184 (Next
6186 else
6190 }
6198 else
6205 /* Get the operand expression. */
6209 /* If this is a qualified expression for a tagged type, we mark the type
6210 as used. Because of polymorphism, this might be the only reference to
6211 the tagged type in the program while objects have it as dynamic type.
6212 The debugger needs to see it to display these objects properly. */
6216 gnu_result
6220 kind == N_Type_Conversion
6227 /* Skip further processing if the conversion is deemed a no-op. */
6229 {
6232 }
6236 /* If the result is a pointer type, see if we are improperly
6237 converting to a stricter alignment. */
6240 {
6246 post_error_ne_tree_2
6250 }
6252 /* If we are converting a descriptor to a function pointer, first
6253 build the pointer. */
6265 {
6270 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6271 subtype. */
6273 {
6276 }
6279 {
6283 gnu_low
6285 gnu_high
6287 }
6288 else
6293 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6294 ensure that GNU_OBJ is evaluated only once and perform a full range
6295 test. */
6297 gnu_result
6299 else
6300 {
6309 gnu_result
6311 }
6314 gnu_result
6316 }
6324 ? RDIV_EXPR
6331 /* These can either be operations on booleans or on modular types.
6332 Fall through for boolean types since that's the way GNU_CODES is
6333 set up. */
6335 {
6336 enum tree_code code
6347 }
6349 /* ... fall through ... */
6361 {
6365 tree gnu_type;
6371 /* Pending generic support for efficient vector logical operations in
6372 GCC, convert vectors to their representative array type view and
6373 fallthrough. */
6377 /* If this is a comparison operator, convert any references to an
6378 unconstrained array value into a reference to the actual array. */
6380 {
6383 }
6385 /* If this is a shift whose count is not guaranteed to be correct,
6386 we need to adjust the shift count. */
6388 {
6390 tree gnu_max_shift
6397 gnu_rhs
6398 = build_binary_op
6401 gnu_count_type,
6402 gnu_max_shift,
6404 integer_one_node)),
6405 gnu_rhs);
6406 }
6408 /* For right shifts, the type says what kind of shift to do,
6409 so we may need to choose a different type. In this case,
6410 we have to ignore integer overflow lest it propagates all
6411 the way down and causes a CE to be explicitly raised. */
6413 {
6416 }
6419 {
6422 }
6425 {
6431 }
6433 /* Instead of expanding overflow checks for addition, subtraction
6434 and multiplication itself, the front end will leave this to
6435 the back end when Backend_Overflow_Checks_On_Target is set.
6436 As the GCC back end itself does not know yet how to properly
6437 do overflow checking, do it here. The goal is to push
6438 the expansions further into the back end over time. */
6447 else
6448 {
6449 /* Some operations, e.g. comparisons of arrays, generate complex
6450 trees that need to be annotated while they are being built. */
6453 }
6455 /* If this is a logical shift with the shift count not verified,
6456 we must return zero if it is too large. We cannot compensate
6457 above in this case. */
6460 gnu_result
6461 = build_cond_expr
6464 gnu_rhs,
6468 gnu_result);
6469 }
6473 {
6476 tree gnu_false
6480 gnu_result
6482 }
6491 /* This case can apply to a boolean or a modular type.
6492 Fall through for a boolean operand since GNU_CODES is set
6493 up to handle this. */
6495 {
6499 gnu_expr);
6501 }
6503 /* ... fall through ... */
6512 gnu_result
6515 else
6521 {
6523 tree gnu_type;
6528 /* The Expression operand can either be an N_Identifier or
6529 Expanded_Name, which must represent a type, or a
6530 N_Qualified_Expression, which contains both the object type and an
6531 initial value for the object. */
6536 {
6537 Entity_Id gnat_desig_type
6545 gnu_init
6551 else
6552 {
6556 }
6558 /* See the N_Qualified_Expression case for the rationale. */
6563 }
6564 else
6571 ignore_init_type);
6572 }
6575 /**************************/
6576 /* Chapter 5: Statements */
6577 /**************************/
6585 /* When not optimizing, turn null statements from source into gotos to
6586 the next statement that the middle-end knows how to preserve. */
6588 {
6599 }
6600 else
6605 /* Get the LHS and RHS of the statement and convert any reference to an
6606 unconstrained array into a reference to the underlying array. */
6609 /* If the type has a size that overflows, convert this into raise of
6610 Storage_Error: execution shouldn't have gotten here anyway. */
6614 N_Raise_Storage_Error);
6616 {
6617 bool outer_atomic_access
6619 bool atomic_access
6620 = !outer_atomic_access
6622 gnu_result
6625 }
6626 else
6627 {
6629 const Entity_Id gnat_type
6631 const bool regular_array_type_p
6633 const bool use_memset_p
6634 = (regular_array_type_p
6638 /* If we'll use memset, we need to find the inner expression. */
6640 {
6641 Node_Id gnat_inner
6645 gnat_inner
6648 }
6649 else
6652 /* If range check is needed, emit code to generate it. */
6655 gnat_node);
6657 /* If an outer atomic access is required on the LHS, build the load-
6658 modify-store sequence. */
6662 /* Or else, if atomic access is required, build the atomic store. */
6666 /* Or else, use memset when the conditions are met. */
6668 {
6672 tree size
6677 {
6678 tree mask
6682 }
6684 }
6686 /* Otherwise build a regular assignment. */
6687 else
6688 gnu_result
6691 /* If the assignment type is a regular array and the two sides are
6692 not completely disjoint, play safe and use memmove. But don't do
6693 it for a bit-packed array as it might not be byte-aligned. */
6695 && regular_array_type_p
6697 {
6701 tree size
6707 }
6708 }
6712 {
6715 /* Make the outer COND_EXPR. Avoid non-determinism. */
6724 /* Now make a COND_EXPR for each of the "else if" parts. Put each
6725 into the previous "else" part and point to where to put any
6726 outer "else". Also avoid non-determinism. */
6730 {
6740 }
6743 }
6755 /* The only way to enter the block is to fall through to it. */
6757 {
6764 }
6765 else
6770 gnu_result
6780 {
6783 /* If the subprogram is a function, we must return the expression. */
6785 {
6788 /* If this function has copy-in/copy-out parameters parameters and
6789 doesn't return by invisible reference, get the real object for
6790 the return. See Subprogram_Body_to_gnu. */
6794 else
6797 /* Get the GCC tree for the expression to be returned. */
6800 /* Do not remove the padding from GNU_RET_VAL if the inner type is
6801 self-referential since we want to allocate the fixed size. */
6803 && type_is_padding_self_referential
6807 /* If the function returns by direct reference, return a pointer
6808 to the return value. */
6813 /* Otherwise, if it returns an unconstrained array, we have to
6814 allocate a new version of the result and return it. */
6816 {
6819 /* And find out whether this is a candidate for Named Return
6820 Value. If so, record it. */
6822 {
6825 /* Strip useless conversions around the return value. */
6829 /* Strip unpadding around the return value. */
6831 && TYPE_IS_PADDING_P
6835 /* Now apply the test to the return value. */
6837 {
6843 }
6844 }
6847 gnu_ret_val,
6852 }
6854 /* Otherwise, if it returns by invisible reference, dereference
6855 the pointer it is passed using the type of the return value
6856 and build the copy operation manually. This ensures that we
6857 don't copy too much data, for example if the return type is
6858 unconstrained with a maximum size. */
6860 {
6861 tree gnu_ret_deref
6863 gnu_ret_obj);
6868 }
6869 }
6871 else
6874 /* If we have a return label defined, convert this into a branch to
6875 that label. The return proper will be handled elsewhere. */
6877 {
6880 gnu_ret_val));
6885 /* When not optimizing, make sure the return is preserved. */
6888 }
6890 /* Otherwise, build a regular return. */
6891 else
6893 }
6897 gnu_result
6901 /***************************/
6902 /* Chapter 6: Subprograms */
6903 /***************************/
6906 /* Unless there is a freeze node, declare the subprogram. We consider
6907 this a "definition" even though we're not generating code for
6908 the subprogram because we will be making the corresponding GCC
6909 node here. */
6918 /* This subprogram doesn't exist for code generation purposes, but we
6919 have to elaborate the types of any parameters and result, unless
6920 they are imported types (nothing to generate in this case).
6922 The parameter list may contain types with freeze nodes, e.g. not null
6923 subtypes, so the subprogram itself may carry a freeze node, in which
6924 case its elaboration must be deferred. */
6926 /* Process the parameter types first. */
6929 = First_Formal_With_Extras
6937 /* Then the result type, set to Standard_Void_Type for procedures. */
6938 {
6939 Entity_Id gnat_temp_type
6944 }
6950 /* For a child unit identifier go up a level to get the specification.
6951 We get this when we try to find the spec of a child unit package
6952 that is the compilation unit being compiled. */
6967 /************************/
6968 /* Chapter 7: Packages */
6969 /************************/
6985 /* If this is the body of a generic package - do nothing. */
6987 {
6990 }
7001 /********************************/
7002 /* Chapter 8: Visibility Rules */
7003 /********************************/
7007 /* Nothing to do here - but these may appear in list of declarations. */
7011 /*********************/
7012 /* Chapter 9: Tasks */
7013 /*********************/
7024 /*********************************************************/
7025 /* Chapter 10: Program Structure and Compilation Issues */
7026 /*********************************************************/
7029 /* This is not called for the main unit on which gigi is invoked. */
7038 /* Simply process whatever unit is being inserted. */
7041 else
7042 {
7045 }
7052 /***************************/
7053 /* Chapter 11: Exceptions */
7054 /***************************/
7057 /* If there is an At_End procedure attached to this node, and the EH
7058 mechanism is SJLJ, we must have at least a corresponding At_End
7059 handler, unless the No_Exception_Handlers restriction is set. */
7074 else
7079 /* Only for reraise in back-end exceptions mode. */
7086 /* Clear the current exception pointer so that the occurrence won't be
7087 deallocated. */
7126 /******************************/
7127 /* Chapter 12: Generic Units */
7128 /******************************/
7138 /* These nodes can appear on a declaration list but there is nothing to
7139 to be done with them. */
7143 /**************************************************/
7144 /* Chapter 13: Representation Clauses and */
7145 /* Implementation-Dependent Features */
7146 /**************************************************/
7151 /* The only one we need to deal with is 'Address since, for the others,
7152 the front-end puts the information elsewhere. */
7156 /* And we only deal with 'Address if the object has a Freeze node. */
7161 /* Get the value to use as the address and save it as the equivalent
7162 for the object. When it is frozen, gnat_to_gnu_entity will do the
7163 right thing. */
7170 /* We do nothing with these. SEM puts the information elsewhere. */
7176 {
7186 /* First retrieve the 3 operand lists built by the front-end. */
7189 {
7196 }
7200 {
7207 }
7211 gnu_clobbers
7214 gnu_clobbers);
7216 /* Then perform some standard checking and processing on the
7217 operands. In particular, mark them addressable if needed. */
7225 {
7227 constraint
7233 {
7234 /* If the operand is going to end up in memory,
7235 mark it addressable. Note that we don't test
7236 allows_mem like in the input case below; this
7237 is modelled on the C front-end. */
7239 {
7246 }
7247 }
7248 else
7252 }
7255 {
7257 constraint
7263 {
7264 /* If the operand is going to end up in memory,
7265 mark it addressable. */
7267 {
7274 }
7275 }
7276 else
7280 }
7286 }
7287 else
7292 /****************/
7293 /* Added Nodes */
7294 /****************/
7297 /* This construct doesn't define a scope so we don't push a binding
7298 level around the statement list, but we wrap it in a SAVE_EXPR to
7299 protect it from unsharing. Elaborate the expression as part of the
7300 same statement group as the actions so that the type declaration
7301 gets inserted there as well. This ensures that the type elaboration
7302 code is issued past the actions computing values on which it might
7303 depend. */
7312 gnu_result
7337 {
7342 /* If this is a thin pointer, we must first dereference it to create
7343 a fat pointer, then go back below to a thin pointer. The reason
7344 for this is that we need to have a fat pointer someplace in order
7345 to properly compute the size. */
7349 gnu_ptr));
7351 /* If this is a fat pointer, the object must have been allocated with
7352 the template in front of the array. So pass the template address,
7353 and get the total size; do it by converting to a thin pointer. */
7355 gnu_ptr
7357 (TYPE_OBJECT_RECORD_TYPE
7359 gnu_ptr);
7363 /* If this is a thin pointer, the object must have been allocated with
7364 the template in front of the array. So pass the template address,
7365 and get the total size. */
7367 gnu_ptr
7369 gnu_ptr,
7371 byte_position
7372 (DECL_CHAIN
7375 /* If we have a special dynamic constrained subtype on the node, use
7376 it to compute the size; otherwise, use the designated subtype. */
7378 {
7379 gnu_actual_obj_type
7383 gnu_actual_obj_type
7385 gnu_actual_obj_type,
7388 }
7389 else
7392 gnu_result
7395 gnu_obj_type,
7398 gnat_node);
7399 }
7407 else
7412 /* The only validation we currently do on an unchecked conversion is
7413 that of aliasing assumptions. */
7425 /* These nodes should only be present when annotating types. */
7431 /* Other nodes are not supposed to reach here. */
7433 }
7435 /* If we pushed the processing of the elaboration routine, pop it back. */
7439 /* When not optimizing, turn boolean rvalues B into B != false tests
7440 so that the code just below can put the location information of the
7441 reference to B on the inequality operator for better debug info. */
7455 boolean_false_node));
7457 /* Set the location information on the result. Note that we may have
7458 no result if we tried to build a CALL_EXPR node to a procedure with
7459 no side-effects and optimization is enabled. */
7463 /* If we're supposed to return something of void_type, it means we have
7464 something we're elaborating for effect, so just return. */
7468 /* If the result is a constant that overflowed, raise Constraint_Error. */
7470 {
7472 gnu_result
7475 N_Raise_Constraint_Error));
7476 }
7478 /* If the result has side-effects and is of an unconstrained type, make a
7479 SAVE_EXPR so that we can be sure it will only be referenced once. But
7480 this is useless for a call to a function that returns an unconstrained
7481 type with default discriminant, as we cannot compute the size of the
7482 actual returned object. We must do this before any conversions. */
7490 /* Now convert the result to the result type, unless we are in one of the
7491 following cases:
7493 1. If this is the LHS of an assignment or an actual parameter of a
7494 call, return the result almost unmodified since the RHS will have
7495 to be converted to our type in that case, unless the result type
7496 has a simpler size. Likewise if there is just a no-op unchecked
7497 conversion in-between. Similarly, don't convert integral types
7498 that are the operands of an unchecked conversion since we need
7499 to ignore those conversions (for 'Valid).
7501 2. If we have a label (which doesn't have any well-defined type), a
7502 field or an error, return the result almost unmodified. Similarly,
7503 if the two types are record types with the same name, don't convert.
7504 This will be the case when we are converting from a packable version
7505 of a type to its original type and we need those conversions to be
7506 NOPs in order for assignments into these types to work properly.
7508 3. If the type is void or if we have no result, return error_mark_node
7509 to show we have no result.
7511 4. If this is a call to a function that returns with variable size and
7512 the call is used as the expression in either an object or a renaming
7513 declaration, return the result unmodified because we want to use the
7514 return slot optimization in this case.
7516 5. Finally, if the type of the result is already correct. */
7534 && (CONTAINS_PLACEHOLDER_P
7538 {
7539 /* Remove padding only if the inner object is of self-referential
7540 size: in that case it must be an object of unconstrained type
7541 with a default discriminant and we want to avoid copying too
7542 much data. */
7545 gnu_result);
7546 }
7555 {
7556 /* Remove any padding. */
7559 gnu_result);
7560 }
7570 ;
7575 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7582 }
7583 \f
7584 /* Subroutine of above to push the exception label stack. GNU_STACK is
7585 a pointer to the stack to update and GNAT_LABEL, if present, is the
7586 label to push onto the stack. */
7588 static void
7590 {
7596 }
7597 \f
7598 /* Record the current code position in GNAT_NODE. */
7600 static void
7602 {
7607 }
7609 /* Insert the code for GNAT_NODE at the position saved for that node. */
7611 static void
7613 {
7616 }
7617 \f
7618 /* Start a new statement group chained to the previous group. */
7620 void
7622 {
7625 /* First see if we can get one from the free list. */
7628 else
7634 }
7636 /* Add GNU_STMT to the current statement group. If it is an expression with
7637 no effects, it is ignored. */
7639 void
7641 {
7643 }
7645 /* Similar, but the statement is always added, regardless of side-effects. */
7647 void
7649 {
7651 }
7653 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7655 void
7657 {
7658 /* Do not emit a location for renamings that come from generic instantiation,
7659 they are likely to disturb debugging. */
7664 }
7666 /* Similar, but the statement is always added, regardless of side-effects. */
7668 void
7670 {
7674 }
7676 /* Add a declaration statement for GNU_DECL to the current statement group.
7677 Get SLOC from Entity_Id. */
7679 void
7681 {
7685 /* If this is a variable that Gigi is to ignore, we may have been given
7686 an ERROR_MARK. So test for it. We also might have been given a
7687 reference for a renaming. So only do something for a decl. Also
7688 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7696 /* If we are external or global, we don't want to output the DECL_EXPR for
7697 this DECL node since we already have evaluated the expressions in the
7698 sizes and positions as globals and doing it again would be wrong. */
7700 {
7701 /* Mark everything as used to prevent node sharing with subprograms.
7702 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7703 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7707 {
7711 }
7712 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
7717 }
7718 else
7721 /* If this is a variable and an initializer is attached to it, it must be
7722 valid for the context. Similar to init_const in create_var_decl_1. */
7729 {
7730 /* If GNU_DECL has a padded type, convert it to the unpadded
7731 type so the assignment is done properly. */
7734 else
7741 {
7744 }
7747 }
7748 }
7750 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
7752 static tree
7754 {
7760 /* Don't mark a dummy type as visited because we want to mark its sizes
7761 and fields once it's filled in. */
7769 }
7771 /* Mark nodes rooted at T with TREE_VISITED and types as having their
7772 sized gimplified. We use this to indicate all variable sizes and
7773 positions in global types may not be shared by any subprogram. */
7775 void
7777 {
7779 }
7781 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
7782 set its location to that of GNAT_NODE if present, but with column info
7783 cleared so that conditional branches generated as part of the cleanup
7784 code do not interfere with coverage analysis tools. */
7786 static void
7788 {
7792 }
7794 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
7796 void
7798 {
7801 }
7803 /* Return code corresponding to the current code group. It is normally
7804 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
7805 BLOCK or cleanups were set. */
7807 tree
7809 {
7813 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
7814 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
7815 make a BIND_EXPR. Note that we nest in that because the cleanup may
7816 reference variables in the block. */
7828 /* Remove this group from the stack and add it to the free list. */
7834 }
7836 /* Return whether the current statement group may fall through. */
7840 {
7843 else
7845 }
7847 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
7848 statements.*/
7850 static void
7852 {
7853 Node_Id gnat_node;
7859 }
7861 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
7862 If BINDING_P is true, push and pop a binding level around the list. */
7864 static tree
7866 {
7876 }
7877 \f
7878 /* Generate GIMPLE in place for the expression at *EXPR_P. */
7880 int
7883 {
7886 tree op;
7892 {
7894 /* If this is an aggregate type, build a null pointer of the appropriate
7895 type and dereference it. */
7900 integer_zero_node));
7901 /* Otherwise, just make a VAR_DECL. */
7902 else
7903 {
7906 }
7912 /* We should only do this if we are just elaborating for side-effects,
7913 but we can't know that yet. */
7920 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
7921 is put into static memory. We know that it's going to be read-only
7922 given the semantics we have and it must be in static memory when the
7923 reference is in an elaboration procedure. */
7925 {
7929 }
7931 /* Replace atomic loads with their first argument. That's necessary
7932 because the gimplifier would create a temporary otherwise. */
7935 {
7938 {
7944 else
7946 }
7947 else
7949 }
7956 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
7957 type to a scalar one, explicitly create the local temporary. That's
7958 required if the type is passed by reference. */
7962 {
7971 }
7978 /* The expressions for the RM bounds must be gimplified to ensure that
7979 they are properly elaborated. See gimplify_decl_expr. */
7983 {
7988 {
7993 {
7997 }
8001 {
8005 }
8007 }
8012 }
8014 /* ... fall through ... */
8018 }
8019 }
8021 /* Generate GIMPLE in place for the statement at *STMT_P. */
8023 static enum gimplify_status
8025 {
8029 {
8035 {
8041 /* Build the condition expression from the test, if any. */
8043 {
8044 /* Deal with the optimization hints. */
8048 annot_expr_ivdep_kind));
8052 annot_expr_no_vector_kind));
8056 annot_expr_vector_kind));
8058 gnu_cond
8061 }
8063 /* Set to emit the statements of the loop. */
8066 /* We first emit the start label and then a conditional jump to the
8067 end label if there's a top condition, then the update if it's at
8068 the top, then the body of the loop, then a conditional jump to
8069 the end label if there's a bottom condition, then the update if
8070 it's at the bottom, and finally a jump to the start label and the
8071 definition of the end label. */
8073 gnu_start_label),
8074 stmt_p);
8095 gnu_end_label),
8096 stmt_p);
8098 }
8101 /* Build a statement to jump to the corresponding end label, then
8102 see if it needs to be conditional. */
8111 }
8112 }
8113 \f
8114 /* Force references to each of the entities in packages withed by GNAT_NODE.
8115 Operate recursively but check that we aren't elaborating something more
8116 than once.
8118 This routine is exclusively called in type_annotate mode, to compute DDA
8119 information for types in withed units, for ASIS use. */
8121 static void
8123 {
8126 /* Process each unit only once. As we trace the context of all relevant
8127 units transitively, including generic bodies, we may encounter the
8128 same generic unit repeatedly. */
8132 /* Save entities in all context units. A body may have an implicit_with
8133 on its own spec, if the context includes a child unit, so don't save
8134 the spec twice. */
8141 {
8145 {
8158 && In_Extended_Main_Code_Unit
8166 }
8168 {
8169 Node_Id gnat_body
8172 /* Retrieve compilation unit node of generic body. */
8177 /* If body is available, elaborate its context. */
8180 }
8181 }
8185 }
8186 \f
8187 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8189 static void
8191 {
8196 /* If this is a package, we need to generate code for the package. */
8198 {
8199 insert_code_for
8203 }
8205 /* Don't do anything for class-wide types as they are always transformed
8206 into their root type. */
8210 /* Check for an old definition. This freeze node might be for an Itype. */
8211 gnu_old
8214 /* If this entity has an address representation clause, GNU_OLD is the
8215 address, so discard it here. */
8219 /* Don't do anything for subprograms that may have been elaborated before
8220 their freeze nodes. This can happen, for example, because of an inner
8221 call in an instance body or because of previous compilation of a spec
8222 for inlining purposes. */
8230 /* If we have a non-dummy type old tree, we have nothing to do, except
8231 aborting if this is the public view of a private type whose full view was
8232 not delayed, as this node was never delayed as it should have been. We
8233 let this happen for concurrent types and their Corresponding_Record_Type,
8234 however, because each might legitimately be elaborated before its own
8235 freeze node, e.g. while processing the other. */
8239 {
8247 }
8249 /* Reset the saved tree, if any, and elaborate the object or type for real.
8250 If there is a full view, elaborate it and use the result. And, if this
8251 is the root type of a class-wide type, reuse it for the latter. */
8253 {
8258 {
8265 {
8268 }
8269 }
8275 }
8279 {
8288 /* Propagate back-annotations from full view to partial view. */
8298 /* The above call may have defined this entity (the simplest example
8299 of this is when we have a private enumeral type since the bounds
8300 will have the public view). */
8303 }
8304 else
8305 {
8306 tree gnu_init
8312 }
8319 /* If we have an old type and we've made pointers to this type, update those
8320 pointers. If this is a Taft amendment type in the main unit, we need to
8321 mark the type as used since other units referencing it don't see the full
8322 declaration and, therefore, cannot mark it as used themselves. */
8324 {
8329 }
8330 }
8331 \f
8332 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8333 We make two passes, one to elaborate anything other than bodies (but
8334 we declare a function if there was no spec). The second pass
8335 elaborates the bodies.
8337 GNAT_END_LIST gives the element in the list past the end. Normally,
8338 this is Empty, but can be First_Real_Statement for a
8339 Handled_Sequence_Of_Statements.
8341 We make a complete pass through both lists if PASS1P is true, then make
8342 the second pass over both lists if PASS2P is true. The lists usually
8343 correspond to the public and private parts of a package. */
8345 static void
8348 {
8350 Node_Id gnat_decl;
8360 {
8361 /* For package specs, we recurse inside the declarations,
8362 thus taking the two pass approach inside the boundary. */
8370 /* Similarly for any declarations in the actions of a
8371 freeze node. */
8373 {
8376 }
8378 /* Package bodies with freeze nodes get their elaboration deferred
8379 until the freeze node, but the code must be placed in the right
8380 place, so record the code position now. */
8388 (Corresponding_Spec
8391 record_code_position
8394 /* We defer most subprogram bodies to the second pass. */
8396 {
8398 {
8404 }
8405 }
8407 /* For bodies and stubs that act as their own specs, the entity
8408 itself must be elaborated in the first pass, because it may
8409 be used in other declarations. */
8411 {
8412 Node_Id gnat_subprog_id
8419 }
8421 /* Concurrent stubs stand for the corresponding subprogram bodies,
8422 which are deferred like other bodies. */
8425 ;
8427 else
8429 }
8431 /* Here we elaborate everything we deferred above except for package bodies,
8432 which are elaborated at their freeze nodes. Note that we must also
8433 go inside things (package specs and freeze nodes) the first pass did. */
8439 {
8455 }
8456 }
8457 \f
8458 /* Make a unary operation of kind CODE using build_unary_op, but guard
8459 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8460 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8461 the operation is to be performed in that type. GNAT_NODE is the gnat
8462 node conveying the source location for which the error should be
8463 signaled. */
8465 static tree
8467 Node_Id gnat_node)
8468 {
8477 }
8479 /* Make a binary operation of kind CODE using build_binary_op, but guard
8480 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8481 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8482 Usually the operation is to be performed in that type. GNAT_NODE is
8483 the GNAT node conveying the source location for which the error should
8484 be signaled. */
8486 static tree
8489 {
8499 /* Assert that the precision is a power of 2. */
8502 /* Prefer a constant or known-positive rhs to simplify checks. */
8508 {
8512 }
8516 /* If we can fold the expression to a constant, just return it.
8517 The caller will deal with overflow, no need to generate a check. */
8522 ? boolean_false_node
8525 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8527 /* Try a few strategies that may be cheaper than the general
8528 code at the end of the function, if the rhs is not known.
8529 The strategies are:
8530 - Call library function for 64-bit multiplication (complex)
8531 - Widen, if input arguments are sufficiently small
8532 - Determine overflow using wrapped result for addition/subtraction. */
8535 {
8536 /* Even for add/subtract double size to get another base type. */
8540 {
8546 }
8550 {
8556 check = build_binary_op
8563 return
8565 }
8568 {
8570 tree wrapped_expr
8576 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8577 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8578 check
8582 boolean_type_node,
8585 return
8587 }
8588 }
8591 {
8593 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8598 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8605 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8610 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8617 /* The check here is designed to be efficient if the rhs is constant,
8618 but it will work for any rhs by using integer division.
8619 Four different check expressions determine whether X * C overflows,
8620 depending on C.
8621 C == 0 => false
8622 C > 0 => X > type_max / C || X < type_min / C
8623 C == -1 => X == type_min
8624 C < -1 => X > type_min / C || X < type_max / C */
8629 check_pos
8632 rhs),
8635 boolean_type_node,
8638 boolean_type_node,
8641 check_neg
8646 type_min),
8649 boolean_type_node,
8652 boolean_type_node,
8658 }
8661 check_pos);
8664 }
8666 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
8667 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
8668 which we have to check. GNAT_NODE is the GNAT node conveying the source
8669 location for which the error should be signaled. */
8671 static tree
8673 {
8677 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
8678 This can for example happen when translating 'Val or 'Value. */
8682 /* Range checks can only be applied to types with ranges. */
8686 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
8687 we can't do anything since we might be truncating the bounds. No
8688 check is needed in this case. */
8694 /* Checked expressions must be evaluated only once. */
8697 /* Note that the form of the check is
8698 (not (expr >= lo)) or (not (expr <= hi))
8699 the reason for this slightly convoluted form is that NaNs
8700 are not considered to be in range in the float case. */
8701 return emit_check
8703 invert_truthvalue
8707 TYPE_MIN_VALUE
8709 invert_truthvalue
8713 TYPE_MAX_VALUE
8716 }
8717 \f
8718 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
8719 we are about to index, GNU_EXPR is the index expression to be checked,
8720 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
8721 has to be checked. Note that for index checking we cannot simply use the
8722 emit_range_check function (although very similar code needs to be generated
8723 in both cases) since for index checking the array type against which we are
8724 checking the indices may be unconstrained and consequently we need to get
8725 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
8726 The place where we need to do that is in subprograms having unconstrained
8727 array formal parameters. GNAT_NODE is the GNAT node conveying the source
8728 location for which the error should be signaled. */
8730 static tree
8733 {
8734 tree gnu_expr_check;
8736 /* Checked expressions must be evaluated only once. */
8739 /* Must do this computation in the base type in case the expression's
8740 type is an unsigned subtypes. */
8743 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
8744 the object we are handling. */
8748 return emit_check
8751 gnu_expr_check,
8753 gnu_low)),
8755 gnu_expr_check,
8757 gnu_high))),
8759 }
8760 \f
8761 /* GNU_COND contains the condition corresponding to an access, discriminant or
8762 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR if
8763 GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
8764 REASON is the code that says why the exception was raised. GNAT_NODE is
8765 the GNAT node conveying the source location for which the error should be
8766 signaled. */
8768 static tree
8770 {
8771 tree gnu_call
8773 tree gnu_result
8777 gnu_expr);
8779 /* GNU_RESULT has side effects if and only if GNU_EXPR has:
8780 we don't need to evaluate it just for the check. */
8784 }
8785 \f
8786 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
8787 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
8788 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
8789 float to integer conversion with truncation; otherwise round.
8790 GNAT_NODE is the GNAT node conveying the source location for which the
8791 error should be signaled. */
8793 static tree
8796 {
8803 /* If we are not doing any checks, the output is an integral type and the
8804 input is not a floating-point type, just do the conversion. This is
8805 required for packed array types and is simpler in all cases anyway. */
8807 && !overflowp
8812 /* First convert the expression to its base type. This
8813 will never generate code, but makes the tests below much simpler.
8814 But don't do this if converting from an integer type to an unconstrained
8815 array type since then we need to get the bounds from the original
8816 (unpacked) type. */
8820 /* If overflow checks are requested, we need to be sure the result will
8821 fit in the output base type. But don't do this if the input
8822 is integer and the output floating-point. */
8825 {
8826 /* Ensure GNU_EXPR only gets evaluated once. */
8834 /* Convert the lower bounds to signed types, so we're sure we're
8835 comparing them properly. Likewise, convert the upper bounds
8836 to unsigned types. */
8850 /* Check each bound separately and only if the result bound
8851 is tighter than the bound on the input type. Note that all the
8852 types are base types, so the bounds must be constant. Also,
8853 the comparison is done in the base type of the input, which
8854 always has the proper signedness. First check for input
8855 integer (which means output integer), output float (which means
8856 both float), or mixed, in which case we always compare.
8857 Note that we have to do the comparison which would *fail* in the
8858 case of an error since if it's an FP comparison and one of the
8859 values is a NaN or Inf, the comparison will fail. */
8866 gnu_cond
8867 = invert_truthvalue
8870 gnu_out_lb)));
8878 gnu_cond
8880 invert_truthvalue
8882 gnu_input,
8884 gnu_out_ub))));
8889 }
8891 /* Now convert to the result base type. If this is a non-truncating
8892 float-to-integer conversion, round. */
8896 {
8902 /* The following calculations depend on proper rounding to even
8903 of each arithmetic operation. In order to prevent excess
8904 precision from spoiling this property, use the widest hardware
8905 floating-point type if FP_ARITH_MAY_WIDEN is true. */
8906 calc_type
8909 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
8913 half_minus_pred_half);
8916 /* If the input is strictly negative, subtract this value
8917 and otherwise add it from the input. For 0.5, the result
8918 is exactly between 1.0 and the machine number preceding 1.0
8919 (for calc_type). Since the last bit of 1.0 is even, this 0.5
8920 will round to 1.0, while all other number with an absolute
8921 value less than 0.5 round to 0.0. For larger numbers exactly
8922 halfway between integers, rounding will always be correct as
8923 the true mathematical result will be closer to the higher
8924 integer compared to the lower one. So, this constant works
8925 for all floating-point numbers.
8927 The reason to use the same constant with subtract/add instead
8928 of a positive and negative constant is to allow the comparison
8929 to be scheduled in parallel with retrieval of the constant and
8930 conversion of the input to the calc_type (if necessary). */
8935 gnu_comp
8937 gnu_add_pred_half
8939 gnu_subtract_pred_half
8943 }
8949 else
8952 /* Finally, do the range check if requested. Note that if the result type
8953 is a modular type, the range check is actually an overflow check. */
8960 }
8961 \f
8962 /* Return true if GNU_EXPR can be directly addressed. This is the case
8963 unless it is an expression involving computation or if it involves a
8964 reference to a bitfield or to an object not sufficiently aligned for
8965 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
8966 be directly addressed as an object of this type.
8968 *** Notes on addressability issues in the Ada compiler ***
8970 This predicate is necessary in order to bridge the gap between Gigi
8971 and the middle-end about addressability of GENERIC trees. A tree
8972 is said to be addressable if it can be directly addressed, i.e. if
8973 its address can be taken, is a multiple of the type's alignment on
8974 strict-alignment architectures and returns the first storage unit
8975 assigned to the object represented by the tree.
8977 In the C family of languages, everything is in practice addressable
8978 at the language level, except for bit-fields. This means that these
8979 compilers will take the address of any tree that doesn't represent
8980 a bit-field reference and expect the result to be the first storage
8981 unit assigned to the object. Even in cases where this will result
8982 in unaligned accesses at run time, nothing is supposed to be done
8983 and the program is considered as erroneous instead (see PR c/18287).
8985 The implicit assumptions made in the middle-end are in keeping with
8986 the C viewpoint described above:
8987 - the address of a bit-field reference is supposed to be never
8988 taken; the compiler (generally) will stop on such a construct,
8989 - any other tree is addressable if it is formally addressable,
8990 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
8992 In Ada, the viewpoint is the opposite one: nothing is addressable
8993 at the language level unless explicitly declared so. This means
8994 that the compiler will both make sure that the trees representing
8995 references to addressable ("aliased" in Ada parlance) objects are
8996 addressable and make no real attempts at ensuring that the trees
8997 representing references to non-addressable objects are addressable.
8999 In the first case, Ada is effectively equivalent to C and handing
9000 down the direct result of applying ADDR_EXPR to these trees to the
9001 middle-end works flawlessly. In the second case, Ada cannot afford
9002 to consider the program as erroneous if the address of trees that
9003 are not addressable is requested for technical reasons, unlike C;
9004 as a consequence, the Ada compiler must arrange for either making
9005 sure that this address is not requested in the middle-end or for
9006 compensating by inserting temporaries if it is requested in Gigi.
9008 The first goal can be achieved because the middle-end should not
9009 request the address of non-addressable trees on its own; the only
9010 exception is for the invocation of low-level block operations like
9011 memcpy, for which the addressability requirements are lower since
9012 the type's alignment can be disregarded. In practice, this means
9013 that Gigi must make sure that such operations cannot be applied to
9014 non-BLKmode bit-fields.
9016 The second goal is achieved by means of the addressable_p predicate,
9017 which computes whether a temporary must be inserted by Gigi when the
9018 address of a tree is requested; if so, the address of the temporary
9019 will be used in lieu of that of the original tree and some glue code
9020 generated to connect everything together. */
9022 static bool
9024 {
9025 /* For an integral type, the size of the actual type of the object may not
9026 be greater than that of the expected type, otherwise an indirect access
9027 in the latter type wouldn't correctly set all the bits of the object. */
9033 /* The size of the actual type of the object may not be smaller than that
9034 of the expected type, otherwise an indirect access in the latter type
9035 would be larger than the object. But only record types need to be
9036 considered in practice for this case. */
9043 {
9048 /* All DECLs are addressable: if they are in a register, we can force
9049 them to memory. */
9054 /* Taking the address of a dereference yields the original pointer. */
9059 /* Taking the address yields a pointer to the constant pool. */
9063 /* Taking the address of a static constructor yields a pointer to the
9064 tree constant pool. */
9076 /* All rvalues are deemed addressable since taking their address will
9077 force a temporary to be created by the middle-end. */
9081 /* The address of a compound expression is that of its 2nd operand. */
9085 /* We accept &COND_EXPR as soon as both operands are addressable and
9086 expect the outcome to be the address of the selected operand. */
9092 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
9093 the field is sufficiently aligned, in case it is subject
9094 to a pragma Component_Alignment. But we don't need to
9095 check the alignment of the containing record, as it is
9096 guaranteed to be not smaller than that of its most
9097 aligned field that is not a bit-field. */
9098 && (!STRICT_ALIGNMENT
9101 /* The field of a padding record is always addressable. */
9115 {
9116 /* This is addressable if we can avoid a copy. */
9120 && (!STRICT_ALIGNMENT
9125 && (!STRICT_ALIGNMENT
9131 }
9135 }
9136 }
9137 \f
9138 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
9139 a separate Freeze node exists, delay the bulk of the processing. Otherwise
9140 make a GCC type for GNAT_ENTITY and set up the correspondence. */
9142 void
9144 {
9145 tree gnu_old
9147 tree gnu_new;
9149 /* If we are to delay elaboration of this type, just do any
9150 elaborations needed for expressions within the declaration and
9151 make a dummy type entry for this node and its Full_View (if
9152 any) in case something points to it. Don't do this if it
9153 has already been done (the only way that can happen is if
9154 the private completion is also delayed). */
9160 {
9164 {
9169 {
9173 }
9174 }
9177 }
9179 /* If we saved away a dummy type for this node it means that this
9180 made the type that corresponds to the full type of an incomplete
9181 type. Clear that type for now and then update the type in the
9182 pointers. */
9184 {
9189 }
9191 /* Now fully elaborate the type. */
9195 /* If we have an old type and we've made pointers to this type, update those
9196 pointers. If this is a Taft amendment type in the main unit, we need to
9197 mark the type as used since other units referencing it don't see the full
9198 declaration and, therefore, cannot mark it as used themselves. */
9200 {
9205 }
9207 /* If this is a record type corresponding to a task or protected type
9208 that is a completion of an incomplete type, perform a similar update
9209 on the type. ??? Including protected types here is a guess. */
9213 {
9214 tree gnu_task_old
9224 }
9225 }
9226 \f
9227 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9228 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9229 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9231 static tree
9233 {
9236 /* We test for GNU_FIELD being empty in the case where a variant
9237 was the last thing since we don't take things off GNAT_ASSOC in
9238 that case. We check GNAT_ASSOC in case we have a variant, but it
9239 has no fields. */
9242 {
9247 /* The expander is supposed to put a single component selector name
9248 in every record component association. */
9251 /* Ignore fields that have Corresponding_Discriminants since we'll
9252 be setting that field in the parent. */
9257 /* Also ignore discriminants of Unchecked_Unions. */
9262 /* Before assigning a value in an aggregate make sure range checks
9263 are done if required. Then convert to the type of the field. */
9269 /* Add the field and expression to the list. */
9271 }
9275 #ifdef ENABLE_CHECKING
9276 /* Verify that every entry in GNU_LIST was used. */
9279 #endif
9282 }
9284 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9285 the first element of an array aggregate. It may itself be an aggregate.
9286 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9287 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9288 for range checking. */
9290 static tree
9292 Entity_Id gnat_component_type)
9293 {
9295 tree gnu_expr;
9299 {
9300 /* If the expression is itself an array aggregate then first build the
9301 innermost constructor if it is part of our array (multi-dimensional
9302 case). */
9308 gnat_component_type);
9309 else
9310 {
9313 /* Before assigning the element to the array, make sure it is
9314 in range. */
9317 }
9324 integer_one_node));
9325 }
9328 }
9329 \f
9330 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9331 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
9332 associations that are from RECORD_TYPE. If we see an internal record, make
9333 a recursive call to fill it in as well. */
9335 static tree
9337 {
9342 {
9345 /* _Parent is an internal field, but may have values in the aggregate,
9346 so check for values first. */
9348 {
9351 }
9354 {
9359 }
9360 else
9361 /* If we have a record subtype, the names will match, but not the
9362 actual FIELD_DECLs. */
9365 {
9368 }
9374 }
9377 }
9378 \f
9379 /* Process a N_Validate_Unchecked_Conversion node. */
9381 static void
9383 {
9387 /* If the target is a pointer type, see if we are either converting from a
9388 non-pointer or from a pointer to a type with a different alias set and
9389 warn if so, unless the pointer has been marked to alias everything. */
9392 {
9402 target_alias_set)))
9403 {
9407 gnat_node);
9410 }
9411 }
9413 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9414 mitigate the problem in this case, so we unconditionally warn. */
9416 {
9417 tree gnu_source_desig_type
9421 tree gnu_target_desig_type
9428 target_alias_set)))
9429 {
9433 gnat_node);
9434 }
9435 }
9436 }
9437 \f
9438 /* EXP is to be treated as an array or record. Handle the cases when it is
9439 an access object and perform the required dereferences. */
9441 static tree
9443 {
9444 /* If the type is a pointer, dereference it. */
9449 /* If we got a padded type, remove it too. */
9454 }
9455 \f
9456 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9457 location and false if it doesn't. In the former case, set the Gigi global
9458 variable REF_FILENAME to the simple debug file name as given by sinput.
9459 If clear_column is true, set column information to 0. */
9461 static bool
9463 {
9468 {
9471 }
9472 else
9473 {
9479 /* We can have zero if pragma Source_Reference is in effect. */
9483 /* Translate the location. */
9485 }
9487 ref_filename
9488 = IDENTIFIER_POINTER
9489 (get_identifier
9493 }
9495 /* Similar to the above, not clearing the column information. */
9497 bool
9499 {
9501 }
9503 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9504 don't do anything if it doesn't correspond to a source location. */
9506 static void
9508 {
9509 location_t locus;
9515 }
9517 /* Similar to the above, not clearing the column information. */
9519 static void
9521 {
9523 }
9525 /* More elaborate version of set_expr_location_from_node to be used in more
9526 general contexts, for example the result of the translation of a generic
9527 GNAT node. */
9529 static void
9531 {
9532 /* Set the location information on the node if it is a real expression.
9533 References can be reused for multiple GNAT nodes and they would get
9534 the location information of their last use. Also make sure not to
9535 overwrite an existing location as it is probably more precise. */
9538 {
9539 CASE_CONVERT:
9548 /* ... fall through ... */
9552 {
9555 }
9557 }
9558 }
9559 \f
9560 /* Return a colon-separated list of encodings contained in encoded Ada
9561 name. */
9565 {
9569 }
9571 /* Extract the Ada name from an encoded name. */
9575 {
9579 }
9580 \f
9581 /* Post an error message. MSG is the error message, properly annotated.
9582 NODE is the node at which to post the error and the node to use for the
9583 '&' substitution. */
9585 void
9587 {
9588 String_Template temp;
9589 String_Pointer sp;
9599 }
9601 /* Similar to post_error, but NODE is the node at which to post the error and
9602 ENT is the node to use for the '&' substitution. */
9604 void
9606 {
9607 String_Template temp;
9608 String_Pointer sp;
9618 }
9620 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
9622 void
9624 {
9627 }
9629 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9630 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9631 most sense. Return true if a sensible assignment was performed. */
9633 static bool
9635 {
9637 location_t end_locus;
9639 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9640 end_locus when there is one. We consider only GNAT nodes with a possible
9641 End_Label attached. If the End_Label actually was unassigned, fallback
9642 on the original node. We'd better assign an explicit sloc associated with
9643 the outer construct in any case. */
9646 {
9659 }
9663 /* Some expanded subprograms have neither an End_Label nor a Sloc
9664 attached. Notify that to callers. For a block statement with no
9665 End_Label, clear column information, so that the tree for a
9666 transient block does not receive the sloc of a source condition. */
9674 {
9685 }
9686 }
9687 \f
9688 /* Similar to post_error_ne, but T is a GCC tree representing the number to
9689 write. If T represents a constant, the text inside curly brackets in
9690 MSG will be output (presumably including a '^'). Otherwise it will not
9691 be output and the text inside square brackets will be output instead. */
9693 void
9695 {
9702 {
9705 }
9706 else
9710 {
9716 ;
9717 else
9719 }
9724 }
9726 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
9728 void
9731 {
9734 }
9735 \f
9736 /* Initialize the table that maps GNAT codes to GCC codes for simple
9737 binary and unary operations. */
9739 static void
9741 {
9767 }
9769 /* Return a label to branch to for the exception type in KIND or NULL_TREE
9770 if none. */
9772 tree
9774 {
9781 else
9783 }
9785 /* Return the decl for the current elaboration procedure. */
9787 tree
9789 {
9791 }