| blob | 693c74f2a084355c54a56f7992ee7ad36167f20b |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2017, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License distributed with GNAT; see file COPYING3. If not see *
19 * <http://www.gnu.org/licenses/>. *
20 * *
21 * GNAT was originally developed by the GNAT team at New York University. *
22 * Extensive contributions were provided by Ada Core Technologies Inc. *
23 * *
24 ****************************************************************************/
69 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
70 for fear of running out of stack space. If we need more, we use xmalloc
71 instead. */
72 #define ALLOCA_THRESHOLD 1000
74 /* Pointers to front-end tables accessed through macros. */
85 /* Highest number in the front-end node table. */
88 /* Current node being treated, in case abort called. */
89 Node_Id error_gnat_node;
91 /* True when gigi is being called on an analyzed but unexpanded
92 tree, and the only purpose of the call is to properly annotate
93 types with representation information. */
96 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
99 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
100 of unconstrained array IN parameters to avoid emitting a great deal of
101 redundant instructions to recompute them each time. */
105 tree first;
106 tree last;
107 tree length;
108 };
115 bitmap named_ret_val;
118 };
120 #define f_parm_attr_cache \
121 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
123 #define f_named_ret_val \
124 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
126 #define f_other_ret_val \
127 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
129 #define f_gnat_ret \
130 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
132 /* A structure used to gather together information about a statement group.
133 We use this to gather related statements, for example the "then" part
134 of a IF. In the case where it represents a lexical scope, we may also
135 have a BLOCK node corresponding to it and/or cleanups. */
142 };
146 /* List of unused struct stmt_group nodes. */
149 /* A structure used to record information on elaboration procedures
150 we've made and need to process.
152 ??? gnat_node should be Node_Id, but gengtype gets confused. */
158 };
162 /* Stack of exception pointer variables. Each entry is the VAR_DECL
163 that stores the address of the raised exception. Nonzero means we
164 are in an exception handler. Not used in the zero-cost case. */
167 /* In ZCX case, current exception pointer. Used to re-raise it. */
170 /* Stack for storing the current elaboration procedure decl. */
173 /* Stack of labels to be used as a goto target instead of a return in
174 some functions. See processing for N_Subprogram_Body. */
177 /* Stack of variable for the return value of a function with copy-in/copy-out
178 parameters. See processing for N_Subprogram_Body. */
181 /* Structure used to record information for a range check. */
183 tree low_bound;
184 tree high_bound;
185 tree disp;
187 tree type;
188 tree invariant_cond;
189 tree inserted_cond;
190 };
195 /* Structure used to record information for a loop. */
197 tree stmt;
198 tree loop_var;
199 tree low_bound;
200 tree high_bound;
205 };
210 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
213 /* The stacks for N_{Push,Pop}_*_Label. */
218 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
253 /* Hooks for debug info back-ends, only supported and used in a restricted set
254 of configurations. */
257 \f
258 /* This is the main program of the back-end. It sets up all the table
259 structures and then generates code. */
261 void
274 Nat number_file,
276 Entity_Id standard_boolean,
277 Entity_Id standard_integer,
278 Entity_Id standard_character,
279 Entity_Id standard_long_long_float,
280 Entity_Id standard_exception_type,
281 Int gigi_operating_mode)
282 {
283 Node_Id gnat_iter;
284 Entity_Id gnat_literal;
304 {
305 /* Use the identifier table to make a permanent copy of the filename as
306 the name table gets reallocated after Gigi returns but before all the
307 debugging information is output. The __gnat_to_canonical_file_spec
308 call translates filenames from pragmas Source_Reference that contain
309 host style syntax not understood by gdb. */
311 = IDENTIFIER_POINTER
312 (get_identifier
313 (__gnat_to_canonical_file_spec
316 /* We rely on the order isomorphism between files and line maps. */
319 /* We create the line map for a source file at once, with a fixed number
320 of columns chosen to avoid jumping over the next power of 2. */
325 }
329 /* Declare the name of the compilation unit as the first global
330 name in order to make the middle-end fully deterministic. */
334 /* Initialize ourselves. */
339 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
340 errors. */
342 {
345 }
347 /* Enable GNAT stack checking method if needed */
351 /* Retrieve alignment settings. */
355 /* Record the builtin types. Define `integer' and `character' first so that
356 dbx will output them first. */
362 /* Save the type we made for integer as the type for Standard.Integer. */
367 /* Likewise for character as the type for Standard.Character. */
373 /* Likewise for boolean as the type for Standard.Boolean. */
392 /* Declare the building blocks of function nodes. */
397 /* Now declare run-time functions. */
399 malloc_decl
401 ftype,
407 free_decl
409 ftype,
414 NULL_TREE);
415 realloc_decl
417 ftype,
421 /* This is used for 64-bit multiplication with overflow checking. */
423 mulv64_decl
430 /* Name of the _Parent field in tagged record types. */
433 /* Name of the Exception_Data type defined in System.Standard_Library. */
434 exception_data_name_id
437 /* Make the types and functions used for exception processing. */
440 jmpbuf_type
446 /* Functions to get and set the jumpbuf pointer for the current thread. */
447 get_jmpbuf_decl
448 = create_subprog_decl
453 set_jmpbuf_decl
454 = create_subprog_decl
457 NULL_TREE),
460 get_excptr_decl
461 = create_subprog_decl
464 NULL_TREE),
470 {
473 }
476 /* setjmp returns an integer and has one operand, which is a pointer to
477 a jmpbuf. */
478 setjmp_decl
479 = create_subprog_decl
482 NULL_TREE),
487 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
488 address. */
489 update_setjmp_buf_decl
490 = create_subprog_decl
497 /* Indicate that it never returns. */
500 NULL_TREE);
502 raise_nodefer_decl
503 = create_subprog_decl
507 set_exception_parameter_decl
508 = create_subprog_decl
511 NULL_TREE),
514 /* Hooks to call when entering/leaving an exception handler. */
517 begin_handler_decl
521 Empty);
522 /* __gnat_begin_handler is a dummy procedure. */
525 end_handler_decl
529 Empty);
531 unhandled_except_decl
535 Empty);
537 /* Indicate that it never returns. */
539 reraise_zcx_decl
543 Empty);
545 /* Dummy objects to materialize "others" and "all others" in the exception
546 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
547 the types to use. */
548 others_decl
555 all_others_decl
562 unhandled_others_decl
569 /* If in no exception handlers mode, all raise statements are redirected to
570 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
571 this procedure will never be called in this mode. */
573 {
574 /* Indicate that it never returns. */
579 tree decl
580 = create_subprog_decl
583 Empty);
586 }
587 else
588 {
589 /* Otherwise, make one decl for each exception reason. */
595 i == CE_Index_Check_Failed
599 }
601 /* Build the special descriptor type and its null node if needed. */
603 {
615 {
616 tree field
623 elt--;
624 }
629 }
631 longest_float_type_node
636 /* If we are using the GCC exception mechanism, let GCC know. */
640 /* Initialize the GCC support for FP operations. */
643 /* Install the builtins we might need, either internally or as user-available
644 facilities for Intrinsic imports. Note that this must be done after the
645 GCC exception mechanism is initialized. */
653 /* Process any Pragma Ident for the main unit. */
658 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
662 /* Save the current optimization options again after the above possible
663 global_options changes. */
667 /* Now translate the compilation unit proper. */
670 /* Disable -Waggressive-loop-optimizations since we implement our own
671 version of the warning. */
674 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
675 the very end to avoid having to second-guess the front-end when we run
676 into dummy nodes during the regular processing. */
681 /* Finally see if we have any elaboration procedures to deal with. */
683 {
686 /* We should have a BIND_EXPR but it may not have any statements in it.
687 If it doesn't have any, we have nothing to do except for setting the
688 flag on the GNAT node. Otherwise, process the function as others. */
694 else
695 {
699 }
700 }
702 /* Destroy ourselves. */
706 /* We cannot track the location of errors past this point. */
708 }
709 \f
710 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
711 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
713 static tree
715 {
724 {
726 ftype
730 }
731 else
732 {
737 ftype
742 }
744 /* Indicate that it never returns. */
746 result
752 }
753 \f
754 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
755 an N_Attribute_Reference. */
757 static int
759 {
761 {
801 }
802 }
804 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
805 is the type that will be used for GNAT_NODE in the translated GNU tree.
806 CONSTANT indicates whether the underlying object represented by GNAT_NODE
807 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
808 whether its value is the address of a constant and ALIASED whether it is
809 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
811 The function climbs up the GNAT tree starting from the node and returns 1
812 upon encountering a node that effectively requires an lvalue downstream.
813 It returns int instead of bool to facilitate usage in non-purely binary
814 logic contexts. */
816 static int
819 {
823 {
833 /* If the parameter is by reference, an lvalue is required. */
839 /* Only the array expression can require an lvalue. */
843 /* ??? Consider that referencing an indexed component with a variable
844 index forces the whole aggregate to memory. Note that testing only
845 for literals is conservative, any static expression in the RM sense
846 could probably be accepted with some additional work. */
856 /* ... fall through ... */
859 /* Only the array expression can require an lvalue. */
873 /* We need to preserve addresses through a renaming. */
877 /* We cannot use a constructor if this is an atomic object because
878 the actual assignment might end up being done component-wise. */
882 /* We don't use a constructor if this is a class-wide object
883 because the effective type of the object is the equivalent
884 type of the class-wide subtype and it smashes most of the
885 data into an array of bytes to which we cannot convert. */
890 /* We cannot use a constructor if the LHS is an atomic object because
891 the actual assignment might end up being done component-wise. */
902 /* ... fall through ... */
906 /* We must look through all conversions because we may need to bypass
907 an intermediate conversion that is meant to be purely formal. */
913 /* We should only reach here through the N_Qualified_Expression case.
914 Force an lvalue for composite types since a block-copy to the newly
915 allocated area of memory is made. */
919 /* We look through dereferences for address of constant because we need
920 to handle the special cases listed above. */
926 /* ... fall through ... */
930 }
933 }
935 /* Return true if T is a constant DECL node that can be safely replaced
936 by its initializer. */
938 static bool
940 {
944 /* Return false for aggregate types that contain a placeholder since
945 their initializers cannot be manipulated easily. */
952 }
954 /* Return an expression equivalent to EXP but where constant DECL nodes
955 have been replaced by their initializer. */
957 static tree
959 {
961 tree op0;
964 {
990 /* If the index is not itself constant, then nothing can be folded. */
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 is not the same as that of the Entity, then
1037 something went wrong, probably in generic instantiation. However, this
1038 does not apply to types. Since we sometime have strange Ekind's, just
1039 do this test for objects. Moreover, if the Etype of the Entity is private
1040 or incomplete coming from a limited context, the Etype of the N_Identifier
1041 is allowed to be the full/non-limited view and we also consider a packed
1042 array type to be the same as the original type. Similarly, a CW type is
1043 equivalent to a subtype of itself. Finally, if the types are Itypes, one
1044 may be a copy of the other, which is also legal. */
1060 == Packed_Array_Impl_Type
1073 /* If this is a reference to a deferred constant whose partial view is an
1074 unconstrained private type, the proper type is on the full view of the
1075 constant, not on the full view of the type, which may be unconstrained.
1077 This may be a reference to a type, for example in the prefix of the
1078 attribute Position, generated for dispatching code (see Make_DT in
1079 exp_disp,adb). In that case we need the type itself, not is parent,
1080 in particular if it is a derived type */
1087 {
1090 }
1091 else
1092 {
1093 /* We want to use the Actual_Subtype if it has already been elaborated,
1094 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1095 simplify things. */
1103 else
1105 }
1107 /* Expand the type of this identifier first, in case it is an enumeral
1108 literal, which only get made when the type is expanded. There is no
1109 order-of-elaboration issue here. */
1112 /* If this is a non-imported elementary constant with an address clause,
1113 retrieve the value instead of a pointer to be dereferenced unless
1114 an lvalue is required. This is generally more efficient and actually
1115 required if this is a static expression because it might be used
1116 in a context where a dereference is inappropriate, such as a case
1117 statement alternative or a record discriminant. There is no possible
1118 volatile-ness short-circuit here since Volatile constants must be
1119 imported per C.6. */
1124 {
1128 }
1131 {
1132 /* If this is a deferred constant, the initializer is attached to
1133 the full view. */
1138 }
1139 else
1142 /* Some objects (such as parameters passed by reference, globals of
1143 variable size, and renamed objects) actually represent the address
1144 of the object. In that case, we must do the dereference. Likewise,
1145 deal with parameters to foreign convention subprograms. */
1150 {
1153 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1156 gnu_result
1159 /* If it's a CONST_DECL, return the underlying constant like below. */
1166 /* If it's a renaming pointer, get to the renamed object. */
1172 /* Otherwise, do the final dereference. */
1173 else
1174 {
1184 }
1185 }
1187 /* If we have a constant declaration and its initializer, try to return the
1188 latter to avoid the need to call fold in lots of places and the need for
1189 elaboration code if this identifier is used as an initializer itself. */
1191 {
1197 /* If there is a (corresponding) variable or this is the address of a
1198 constant, we only want to return the initializer if an lvalue isn't
1199 required. Evaluate this now if we have not already done so. */
1201 require_lvalue
1205 /* Finally retrieve the initializer if this is deemed valid. */
1208 }
1210 /* But for a constant renaming we couldn't do that incrementally for its
1211 definition because of the need to return an lvalue so, if the present
1212 context doesn't itself require an lvalue, we try again here. */
1216 {
1218 require_lvalue
1223 }
1225 /* The GNAT tree has the type of a function set to its result type, so we
1226 adjust here. Also use the type of the result if the Etype is a subtype
1227 that is nominally unconstrained. Likewise if this is a deferred constant
1228 of a discriminated type whose full view can be elaborated statically, to
1229 avoid problematic conversions to the nominal subtype. But remove any
1230 padding from the resulting type. */
1237 {
1241 }
1246 }
1247 \f
1248 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1249 any statements we generate. */
1251 static tree
1253 {
1256 Node_Id gnat_temp;
1258 /* Do nothing if we are just annotating types and check for (and ignore)
1259 unrecognized pragmas. */
1266 {
1268 /* Do nothing at top level: all such variables are already viewable. */
1275 {
1279 machine_mode mode;
1280 scalar_int_mode int_mode;
1282 #ifdef ASM_COMMENT_START
1284 #endif
1289 /* Use the value only if it fits into a normal register,
1290 otherwise use the address. */
1298 #ifdef ASM_COMMENT_START
1304 NULL);
1307 #endif
1309 asm_constraint,
1310 NULL_TREE,
1311 tree_cons
1319 }
1326 {
1330 {
1353 }
1354 }
1360 {
1378 }
1388 {
1389 Node_Id gnat_expr;
1390 /* Preserve the location of the pragma. */
1394 diagnostic_t kind;
1399 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1401 {
1403 {
1416 }
1419 }
1421 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1423 {
1425 {
1436 }
1438 /* Deal with optional pattern (but ignore Reason => "..."). */
1441 {
1442 /* pragma Warnings (On | Off, Name) is handled differently. */
1447 }
1448 else
1452 }
1454 else
1457 /* This is the same implementation as in the C family of compilers. */
1461 {
1469 {
1472 }
1474 {
1477 }
1479 {
1482 }
1485 }
1486 else
1493 }
1498 }
1501 }
1502 \f
1504 /* Check the inline status of nested function FNDECL wrt its parent function.
1506 If a non-inline nested function is referenced from an inline external
1507 function, we cannot honor both requests at the same time without cloning
1508 the nested function in the current unit since it is private to its unit.
1509 We could inline it as well but it's probably better to err on the side
1510 of too little inlining.
1512 This must be done only on nested functions present in the source code
1513 and not on nested functions generated by the compiler, e.g. finalizers,
1514 because they may be not marked inline and we don't want them to block
1515 the inlining of the parent function. */
1517 static void
1519 {
1528 {
1533 {
1536 }
1537 else
1538 {
1540 fndecl);
1542 }
1546 }
1547 }
1548 \f
1549 /* Return an expression for the length of TYPE, an integral type, computed in
1550 RESULT_TYPE, another integral type.
1552 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1553 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1554 which would only overflow in much rarer cases, for extremely large arrays
1555 we expect never to encounter in practice. Besides, the former computation
1556 required the use of potentially constraining signed arithmetics while the
1557 latter does not. Note that the comparison must be done in the original
1558 base index type in order to avoid any overflow during the conversion. */
1560 static tree
1562 {
1567 tree length
1573 length
1579 }
1581 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1582 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1583 where we should place the result type. ATTRIBUTE is the attribute ID. */
1585 static tree
1587 {
1594 /* If the input is a NULL_EXPR, make a new one. */
1596 {
1600 }
1603 {
1606 /* These are just conversions since representation clauses for
1607 enumeration types are handled in the front-end. */
1617 /* These just add or subtract the constant 1 since representation
1618 clauses for enumeration types are handled in the front-end. */
1624 gnu_result
1631 /* Conversions don't change addresses but can cause us to miss the
1632 COMPONENT_REF case below, so strip them off. */
1636 /* If we are taking 'Address of an unconstrained object, this is the
1637 pointer to the underlying array. */
1641 /* If we are building a static dispatch table, we have to honor
1642 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1643 with the C++ ABI. We do it in the non-static case as well,
1644 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1647 {
1649 /* Descriptors can only be built here for top-level functions. */
1657 /* If we're not going to build the descriptor, we have to retrieve
1658 the one which will be built by the linker (or by the compiler
1659 later if a static chain is requested). */
1661 {
1664 gnu_result);
1666 }
1673 {
1675 {
1679 }
1680 else
1686 elt--;
1687 }
1691 }
1693 /* ... fall through ... */
1699 gnu_result
1706 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1707 don't try to build a trampoline. */
1709 {
1715 /* On targets for which function symbols denote a descriptor, the
1716 code address is stored within the first slot of the descriptor
1717 so we do an additional dereference:
1718 result = *((result_type *) result)
1719 where we expect result to be of some pointer type already. */
1721 gnu_result
1724 gnu_result));
1725 }
1727 /* For 'Access, issue an error message if the prefix is a C++ method
1728 since it can use a special calling convention on some platforms,
1729 which cannot be propagated to the access type. */
1734 gnat_node);
1736 /* For other address attributes applied to a nested function,
1737 find an inner ADDR_EXPR and annotate it so that we can issue
1738 a useful warning with -Wtrampolines. */
1740 {
1745 {
1748 /* Also check the inlining status. */
1751 /* Moreover, for 'Access or 'Unrestricted_Access with non-
1752 foreign-compatible representation, mark the ADDR_EXPR so
1753 that we can build a descriptor instead of a trampoline. */
1760 /* Otherwise, we need to check that we are not violating the
1761 No_Implicit_Dynamic_Code restriction. */
1764 }
1765 }
1769 {
1771 tree gnu_obj_type;
1775 /* If this is fat pointer, the object must have been allocated with the
1776 template in front of the array. So compute the template address; do
1777 it by converting to a thin pointer. */
1779 gnu_ptr
1781 (TYPE_OBJECT_RECORD_TYPE
1783 gnu_ptr);
1787 /* If this is a thin pointer, the object must have been allocated with
1788 the template in front of the array. So compute the template address
1789 and return it. */
1791 gnu_ptr
1793 gnu_ptr,
1795 byte_position
1796 (DECL_CHAIN
1800 }
1809 /* Remove NOPs and conversions between original and packable version
1810 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1811 to see if a COMPONENT_REF was involved. */
1816 == RECORD_TYPE
1825 /* Replace an unconstrained array type with the type of the underlying
1826 array. We can't do this with a call to maybe_unconstrained_array
1827 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1828 use the record type that will be used to allocate the object and its
1829 template. */
1831 {
1835 }
1837 /* If we're looking for the size of a field, return the field size. */
1841 /* Otherwise, if the prefix is an object, or if we are looking for
1842 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1843 GCC size of the type. We make an exception for padded objects,
1844 as we do not take into account alignment promotions for the size.
1845 This is in keeping with the object case of gnat_to_gnu_entity. */
1851 {
1852 /* If this is a dereference and we have a special dynamic constrained
1853 subtype on the prefix, use it to compute the size; otherwise, use
1854 the designated subtype. */
1856 {
1857 Node_Id gnat_actual_subtype
1859 tree gnu_ptr_type
1864 {
1865 tree gnu_actual_obj_type
1867 gnu_type
1869 gnu_actual_obj_type,
1872 }
1873 }
1876 }
1878 /* Otherwise, the result is the RM size of the type. */
1879 else
1882 /* Deal with a self-referential size by returning the maximum size for
1883 a type and by qualifying the size with the object otherwise. */
1885 {
1888 else
1890 }
1892 /* If the type contains a template, subtract its size. */
1898 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1906 {
1919 else
1920 {
1925 /* If the default alignment of "double" or larger scalar types is
1926 specifically capped and there is an alignment clause neither
1927 on the type nor on the prefix itself, return the cap. */
1929 is_capped_double
1932 is_capped_double
1934 else
1944 else
1946 }
1949 }
1958 {
1965 else
1968 }
1970 /* ... fall through ... */
1973 {
1981 /* Make sure any implicit dereference gets done. */
1985 /* We treat unconstrained array In parameters specially. We also note
1986 whether we are dereferencing a pointer to unconstrained array. */
1989 {
1991 /* This is the direct case. */
1997 /* This is the indirect case. Note that we need to be sure that
1998 the access value cannot be null as we'll hoist the load. */
2001 {
2004 }
2005 else
2011 }
2013 /* If the prefix is the view conversion of a constrained array to an
2014 unconstrained form, we retrieve the constrained array because we
2015 might not be able to substitute the PLACEHOLDER_EXPR coming from
2016 the conversion. This can occur with the 'Old attribute applied
2017 to a parameter with an unconstrained type, which gets rewritten
2018 into a constrained local variable very late in the game. */
2021 && !CONTAINS_PLACEHOLDER_P
2024 else
2031 {
2033 tree gnu_type_temp;
2039 ;
2042 }
2049 /* When not optimizing, look up the slot associated with the parameter
2050 and the dimension in the cache and create a new one on failure.
2051 Don't do this when the actual subtype needs debug info (this happens
2052 with -gnatD): in elaborate_expression_1, we create variables that
2053 hold the bounds, so caching attributes isn't very interesting and
2054 causes dependency issues between these variables and cached
2055 expressions. */
2060 {
2066 {
2071 }
2072 }
2074 /* Return the cached expression or build a new one. */
2076 {
2078 {
2081 }
2083 gnu_result
2085 }
2088 {
2090 {
2093 }
2095 gnu_result
2097 }
2100 {
2102 {
2105 }
2107 gnu_result
2109 gnu_result_type);
2110 }
2112 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2113 handling. Note that these attributes could not have been used on
2114 an unconstrained array type. */
2117 /* Cache the expression we have just computed. Since we want to do it
2118 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2119 create the temporary in the outermost binding level. We will make
2120 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2121 paths by forcing its evaluation on entry of the function. */
2123 {
2124 gnu_result
2127 {
2143 }
2144 }
2146 /* Otherwise, evaluate it each time it is referenced. */
2147 else
2149 {
2152 /* If we are dereferencing a pointer to unconstrained array, we
2153 need to capture the value because the pointed-to bounds may
2154 subsequently be released. */
2156 gnu_result
2162 /* Set the source location onto the predicate of the condition
2163 but not if the expression is cached to avoid messing up the
2164 debug info. */
2168 gnat_node);
2173 }
2176 }
2183 {
2184 HOST_WIDE_INT bitsize;
2185 HOST_WIDE_INT bitpos;
2186 tree gnu_offset;
2187 tree gnu_field_bitpos;
2188 tree gnu_field_offset;
2189 tree gnu_inner;
2190 machine_mode mode;
2197 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2198 the result is 0. Don't allow 'Bit on a bare component, though. */
2202 {
2205 }
2207 else
2216 {
2224 {
2225 gnu_field_bitpos
2228 gnu_field_offset
2231 }
2232 }
2234 {
2237 }
2238 else
2239 {
2242 }
2245 {
2259 /* ??? Avoid a large unsigned result that will overflow when
2260 converted to the signed universal_integer. */
2263 else
2264 gnu_result
2271 }
2273 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2274 handling. */
2277 }
2281 {
2287 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2288 a NaN so we implement the semantics of C99 f{min,max} to make it
2289 predictable in this case: if either operand is a NaN, the other
2290 is returned; if both operands are NaN's, a NaN is returned. */
2293 {
2299 /* If the operands have side-effects, they need to be evaluated
2300 only once in spite of the multiple references in the result. */
2308 integer_zero_node);
2312 integer_zero_node);
2322 /* If the operands have side-effects, they need to be evaluated
2323 before doing the tests above since the place they otherwise
2324 would end up being evaluated at run time could be wrong. */
2326 gnu_result
2330 gnu_result
2332 }
2333 else
2337 }
2363 /* Note this size cannot be self-referential. */
2373 /* What we want is the offset of the ARRAY field in the record
2374 that the thin pointer designates. */
2382 /* This is just a zero cast to the pointer type for our prefix and
2383 dereferenced. */
2385 gnu_result
2388 integer_zero_node));
2393 {
2400 {
2405 ;
2406 }
2414 && (DECL_BY_COMPONENT_PTR_P
2418 }
2422 /* We treat Model as identical to Machine. This is true for at least
2423 IEEE and some other nice floating-point systems. */
2425 /* ... fall through ... */
2428 /* The trick is to force the compiler to store the result in memory so
2429 that we do not have extra precision used. But do this only when this
2430 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2431 the type is lower than that of the longest floating-point type. */
2438 && fp_arith_may_widen
2441 {
2443 tree field
2453 asm_expr
2465 gnu_result
2469 }
2476 /* This can be a random address so build an alias-all pointer type. */
2477 gnu_expr
2480 gnu_expr);
2485 /* This abort means that we have an unimplemented attribute. */
2487 }
2489 /* If this is an attribute where the prefix was unused, force a use of it if
2490 it has a side-effect. But don't do it if the prefix is just an entity
2491 name. However, if an access check is needed, we must do it. See second
2492 example in AARM 11.6(5.e). */
2496 gnu_result
2501 }
2502 \f
2503 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2504 to a GCC tree, which is returned. */
2506 static tree
2508 {
2510 Node_Id gnat_when;
2511 location_t end_locus;
2519 /* We build a SWITCH_EXPR that contains the code with interspersed
2520 CASE_LABEL_EXPRs for each label. */
2529 {
2531 Node_Id gnat_choice;
2533 /* First compile all the different case choices for the current WHEN
2534 alternative. */
2538 {
2543 {
2558 /* This represents either a subtype range or a static value of
2559 some kind; Ekind says which. */
2561 {
2567 }
2569 /* ... fall through ... */
2581 }
2583 /* Everything should be folded into constants at this point. */
2593 gnat_choice);
2595 }
2597 /* This construct doesn't define a scope so we shouldn't push a binding
2598 level around the statement list. Except that we have always done so
2599 historically and this makes it possible to reduce stack usage. As a
2600 compromise, we keep doing it for case statements, for which this has
2601 never been problematic, but not for case expressions in Ada 2012. */
2603 {
2604 const bool is_case_expression
2606 tree group
2611 {
2616 }
2617 }
2618 }
2620 /* Now emit a definition of the label the cases branch to, if any. */
2623 gnu_result
2627 }
2628 \f
2629 /* Return true if we are in the body of a loop. */
2633 {
2635 }
2637 /* Find out whether EXPR is a simple additive expression based on the iteration
2638 variable of some enclosing loop in the current function. If so, return the
2639 loop and set *DISP to the displacement and *NEG_P to true if this is for a
2640 subtraction; otherwise, return NULL. */
2644 {
2651 {
2657 }
2658 else
2659 {
2665 }
2682 }
2684 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2685 false, or the maximum value if MAX is true, of TYPE. */
2687 static bool
2689 {
2696 val = (max
2705 else
2707 }
2709 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2710 If REVERSE is true, minimum value is taken as maximum value. */
2714 {
2716 }
2718 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2719 If REVERSE is true, maximum value is taken as minimum value. */
2723 {
2725 }
2727 /* Return true if VAL1 can be lower than VAL2. */
2729 static bool
2731 {
2745 }
2747 /* Replace EXPR1 and EXPR2 by invariant expressions if possible. Return
2748 true if both expressions have been replaced and false otherwise. */
2750 static bool
2752 {
2763 }
2765 /* Helper function for walk_tree, used by independent_iterations_p below. */
2767 static tree
2769 {
2773 /* No need to walk into types or decls. */
2781 }
2783 /* Return true if STMT_LIST generates independent iterations in a loop. */
2785 static bool
2787 {
2788 tree_stmt_iterator tsi;
2791 tree iter;
2797 /* Scan the list and return false on anything that is not either a check
2798 or an assignment to a parameter with restricted aliasing. */
2800 {
2804 {
2806 {
2815 }
2818 {
2831 }
2835 }
2836 }
2838 /* At this point we know that the list contains only statements that will
2839 modify parameters with restricted aliasing. Check that the statements
2840 don't at the time read from these parameters. */
2846 }
2848 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2849 to a GCC tree, which is returned. */
2851 static tree
2853 {
2860 tree gnu_result;
2862 /* Push the loop_info structure associated with the LOOP_STMT. */
2865 /* Set location information for statement and end label. */
2871 /* Save the statement for later reuse. */
2875 /* Set the condition under which the loop must keep going.
2876 For the case "LOOP .... END LOOP;" the condition is always true. */
2878 ;
2880 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2885 /* Otherwise we have an iteration scheme and the condition is given by the
2886 bounds of the subtype of the iteration variable. */
2887 else
2888 {
2902 /* We must disable modulo reduction for the iteration variable, if any,
2903 in order for the loop comparison to be effective. */
2905 {
2911 }
2912 else
2913 {
2919 }
2921 /* We use two different strategies to translate the loop, depending on
2922 whether optimization is enabled.
2924 If it is, we generate the canonical loop form expected by the loop
2925 optimizer and the loop vectorizer, which is the do-while form:
2927 ENTRY_COND
2928 loop:
2929 TOP_UPDATE
2930 BODY
2931 BOTTOM_COND
2932 GOTO loop
2934 This avoids an implicit dependency on loop header copying and makes
2935 it possible to turn BOTTOM_COND into an inequality test.
2937 If optimization is disabled, loop header copying doesn't come into
2938 play and we try to generate the loop form with the fewer conditional
2939 branches. First, the default form, which is:
2941 loop:
2942 TOP_COND
2943 BODY
2944 BOTTOM_UPDATE
2945 GOTO loop
2947 It should catch most loops with constant ending point. Then, if we
2948 cannot, we try to generate the shifted form:
2950 loop:
2951 TOP_COND
2952 TOP_UPDATE
2953 BODY
2954 GOTO loop
2956 which should catch loops with constant starting point. Otherwise, if
2957 we cannot, we generate the fallback form:
2959 ENTRY_COND
2960 loop:
2961 BODY
2962 BOTTOM_COND
2963 BOTTOM_UPDATE
2964 GOTO loop
2966 which works in all cases. */
2969 {
2970 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2971 overflow. */
2973 ;
2975 /* Otherwise, use the do-while form with the help of a special
2976 induction variable in the unsigned version of the base type
2977 or the unsigned version of the size type, whichever is the
2978 largest, in order to have wrap-around arithmetics for it. */
2979 else
2980 {
2983 gnu_base_type
2985 else
2992 }
2994 gnu_first
2996 gnu_one_node);
2999 }
3000 else
3001 {
3002 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
3004 ;
3006 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
3007 GNU_LAST-1 does. */
3010 {
3011 gnu_first
3013 gnu_one_node);
3014 gnu_last
3016 gnu_one_node);
3018 }
3020 /* Otherwise, use the fallback form. */
3021 else
3023 }
3025 /* If we use the BOTTOM_COND, we can turn the test into an inequality
3026 test but we may have to add ENTRY_COND to protect the empty loop. */
3028 {
3031 {
3032 gnu_cond_expr
3038 }
3039 }
3041 /* Open a new nesting level that will surround the loop to declare the
3042 iteration variable. */
3046 /* If we use the special induction variable, create it and set it to
3047 its initial value. Morever, the regular iteration variable cannot
3048 itself be initialized, lest the initial value wrapped around. */
3050 {
3051 gnu_loop_iv
3055 }
3056 else
3059 /* Declare the iteration variable and set it to its initial value. */
3064 {
3067 }
3072 /* Do all the arithmetics in the base type. */
3075 /* Set either the top or bottom exit condition. */
3079 gnu_last);
3080 else
3083 gnu_last);
3085 /* Set either the top or bottom update statement and give it the source
3086 location of the iteration for better coverage info. */
3088 {
3089 gnu_stmt
3096 gnu_stmt
3098 gnu_loop_iv);
3102 }
3103 else
3104 {
3105 gnu_stmt
3111 }
3112 }
3114 /* If the loop was named, have the name point to this loop. In this case,
3115 the association is not a DECL node, but the end label of the loop. */
3119 /* Make the loop body into its own block, so any allocated storage will be
3120 released every iteration. This is needed for stack allocation. */
3125 /* If we have an iteration scheme, then we are in a statement group. Add
3126 the LOOP_STMT to it, finish it and make it the "loop". */
3128 {
3129 /* First, if we have computed invariant conditions for range (or index)
3130 checks applied to the iteration variable, find out whether they can
3131 be evaluated to false at compile time; otherwise, if there are not
3132 too many of them, combine them with the original checks. If loop
3133 unswitching is enabled, do not require the loop bounds to be also
3134 invariant, as their evaluation will still be ahead of the loop. */
3137 {
3142 {
3146 {
3149 gnu_adjusted_low
3152 low_ok
3155 }
3156 else
3160 {
3163 gnu_adjusted_high
3166 high_ok
3169 }
3170 else
3173 tree range_ok
3177 rci->invariant_cond
3182 else
3183 n_remaining_checks++;
3184 }
3186 /* Note that loop unswitching can only be applied a small number of
3187 times to a given loop (PARAM_MAX_UNSWITCH_LEVEL default to 3). */
3192 {
3197 }
3198 }
3200 /* Second, if loop vectorization is enabled and the iterations of the
3201 loop can easily be proved as independent, mark the loop. */
3203 && flag_tree_loop_vectorize
3210 }
3212 /* If we have an outer COND_EXPR, that's our result and this loop is its
3213 "true" statement. Otherwise, the result is the LOOP_STMT. */
3215 {
3219 }
3220 else
3226 }
3227 \f
3228 /* This page implements a form of Named Return Value optimization modelled
3229 on the C++ optimization of the same name. The main difference is that
3230 we disregard any semantical considerations when applying it here, the
3231 counterpart being that we don't try to apply it to semantically loaded
3232 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3234 We consider a function body of the following GENERIC form:
3236 return_type R1;
3237 [...]
3238 RETURN_EXPR [<retval> = ...]
3239 [...]
3240 RETURN_EXPR [<retval> = R1]
3241 [...]
3242 return_type Ri;
3243 [...]
3244 RETURN_EXPR [<retval> = ...]
3245 [...]
3246 RETURN_EXPR [<retval> = Ri]
3247 [...]
3249 where the Ri are not addressable and we try to fulfill a simple criterion
3250 that would make it possible to replace one or several Ri variables by the
3251 single RESULT_DECL of the function.
3253 The first observation is that RETURN_EXPRs that don't directly reference
3254 any of the Ri variables on the RHS of their assignment are transparent wrt
3255 the optimization. This is because the Ri variables aren't addressable so
3256 any transformation applied to them doesn't affect the RHS; moreover, the
3257 assignment writes the full <retval> object so existing values are entirely
3258 discarded.
3260 This property can be extended to some forms of RETURN_EXPRs that reference
3261 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3262 case, in particular when function calls are involved.
3264 Therefore the algorithm is as follows:
3266 1. Collect the list of candidates for a Named Return Value (Ri variables
3267 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3268 other expressions on the RHS of such assignments.
3270 2. Prune the members of the first list (candidates) that are referenced
3271 by a member of the second list (expressions).
3273 3. Extract a set of candidates with non-overlapping live ranges from the
3274 first list. These are the Named Return Values.
3276 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3277 Named Return Values in the function with the RESULT_DECL.
3279 If the function returns an unconstrained type, things are a bit different
3280 because the anonymous return object is allocated on the secondary stack
3281 and RESULT_DECL is only a pointer to it. Each return object can be of a
3282 different size and is allocated separately so we need not care about the
3283 addressability and the aforementioned overlapping issues. Therefore, we
3284 don't collect the other expressions and skip step #2 in the algorithm. */
3286 struct nrv_data
3287 {
3288 bitmap nrv;
3289 tree result;
3290 Node_Id gnat_ret;
3292 };
3294 /* Return true if T is a Named Return Value. */
3298 {
3300 }
3302 /* Helper function for walk_tree, used by finalize_nrv below. */
3304 static tree
3306 {
3310 /* No need to walk into types or decls. */
3318 }
3320 /* Prune Named Return Values in BLOCK and return true if there is still a
3321 Named Return Value in BLOCK or one of its sub-blocks. */
3323 static bool
3325 {
3327 tree t;
3329 /* First recurse on the sub-blocks. */
3333 /* Then make sure to keep at most one NRV per block. */
3336 {
3339 else
3341 }
3344 }
3346 /* Helper function for walk_tree, used by finalize_nrv below. */
3348 static tree
3350 {
3354 /* No need to walk into types. */
3358 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3359 nop, but differs from using NULL_TREE in that it indicates that we care
3360 about the value of the RESULT_DECL. */
3363 {
3366 /* Strip useless conversions around the return value. */
3372 }
3374 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3375 if needed. */
3378 {
3382 {
3387 }
3388 else
3392 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3395 /* ??? Kludge to avoid an assertion failure during inlining. */
3398 }
3400 /* And replace all uses of NRVs with the RESULT_DECL. */
3404 /* Avoid walking into the same tree more than once. Unfortunately, we
3405 can't just use walk_tree_without_duplicates because it would only
3406 call us for the first occurrence of NRVs in the function body. */
3411 }
3413 /* Likewise, but used when the function returns an unconstrained type. */
3415 static tree
3417 {
3421 /* No need to walk into types. */
3425 /* We need to see the DECL_EXPR of NRVs before any other references so we
3426 walk the body of BIND_EXPR before walking its variables. */
3430 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3431 return value built by the allocator instead of the whole construct. */
3434 {
3437 /* This is the construct returned by the allocator. */
3440 {
3445 else
3447 }
3449 /* Strip useless conversions around the return value. */
3454 /* Strip unpadding around the return value. */
3459 /* Assign the new return value to the RESULT_DECL. */
3463 }
3465 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3466 into a new variable. */
3469 {
3476 /* Create an artificial context to build the allocation. */
3481 /* This will return a COMPOUND_EXPR with the allocation in the first
3482 arm and the final return value in the second arm. */
3489 /* The new variable is built as a reference to the allocated space. */
3490 new_var
3496 {
3499 /* The new initial value is a COMPOUND_EXPR with the allocation in
3500 the first arm and the value of P_ARRAY in the second arm. */
3506 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3513 }
3514 else
3515 {
3516 /* The new initial value is just the allocation. */
3519 }
3523 /* Destroy the artificial context and insert the new statements. */
3528 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3533 /* Save the new return value and the dereference of NEW_VAR. */
3537 /* ??? Kludge to avoid messing up during inlining. */
3539 }
3541 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3545 /* Avoid walking into the same tree more than once. Unfortunately, we
3546 can't just use walk_tree_without_duplicates because it would only
3547 call us for the first occurrence of NRVs in the function body. */
3552 }
3554 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3555 contains the candidates for Named Return Value and OTHER is a list of
3556 the other return values. GNAT_RET is a representative return node. */
3558 static void
3560 {
3563 walk_tree_fn func;
3565 tree iter;
3567 /* We shouldn't be applying the optimization to return types that we aren't
3568 allowed to manipulate freely. */
3571 /* Prune the candidates that are referenced by other return values. */
3581 /* Prune also the candidates that are referenced by nested functions. */
3589 /* Extract a set of NRVs with non-overlapping live ranges. */
3593 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3600 else
3604 }
3606 /* Return true if RET_VAL can be used as a Named Return Value for the
3607 anonymous return object RET_OBJ. */
3609 static bool
3611 {
3624 /* For the constrained case, test for addressability. */
3628 /* For the constrained case, test for overalignment. */
3632 /* For the unconstrained case, test for bogus initialization. */
3639 }
3641 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3642 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3643 around RESULT_OBJ, which may be null in this case. */
3645 static tree
3647 {
3648 tree result_expr;
3651 {
3652 /* The gimplifier explicitly enforces the following invariant:
3654 RETURN_EXPR
3655 |
3656 INIT_EXPR
3657 / \
3658 / \
3659 RET_OBJ ...
3661 As a consequence, type consistency dictates that we use the type
3662 of the RET_OBJ as the operation type. */
3665 /* Convert the right operand to the operation type. Note that this is
3666 the transformation applied in the INIT_EXPR case of build_binary_op,
3667 with the assumption that the type cannot involve a placeholder. */
3671 /* We always can use an INIT_EXPR for the return object. */
3674 /* If the function returns an aggregate type, find out whether this is
3675 a candidate for Named Return Value. If so, record it. Otherwise,
3676 if this is an expression of some kind, record it elsewhere. */
3682 {
3683 /* Strip useless conversions around the return value. */
3687 /* Now apply the test to the return value. */
3689 {
3693 }
3695 /* Note that we need not care about CONSTRUCTORs here, as they are
3696 totally transparent given the read-compose-write semantics of
3697 assignments from CONSTRUCTORs. */
3700 }
3701 }
3702 else
3706 }
3707 \f
3708 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3709 don't return anything. */
3711 static void
3713 {
3714 /* Defining identifier of a parameter to the subprogram. */
3715 Entity_Id gnat_param;
3716 /* The defining identifier for the subprogram body. Note that if a
3717 specification has appeared before for this body, then the identifier
3718 occurring in that specification will also be a defining identifier and all
3719 the calls to this subprogram will point to that specification. */
3720 Entity_Id gnat_subprog_id
3723 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3724 tree gnu_subprog_decl;
3725 /* Its RESULT_DECL node. */
3726 tree gnu_result_decl;
3727 /* Its FUNCTION_TYPE node. */
3728 tree gnu_subprog_type;
3729 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3730 tree gnu_cico_list;
3731 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3733 tree gnu_result;
3734 location_t locus;
3738 /* If this is a generic object or if it has been eliminated,
3739 ignore it. */
3745 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3746 the already-elaborated tree node. However, if this subprogram had its
3747 elaboration deferred, we will already have made a tree node for it. So
3748 treat it as not being defined in that case. Such a subprogram cannot
3749 have an address clause or a freeze node, so this test is safe, though it
3750 does disable some otherwise-useful error checking. */
3751 gnu_subprog_decl
3762 /* If the function returns by invisible reference, make it explicit in the
3763 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3765 {
3769 }
3771 /* Set the line number in the decl to correspond to that of the body. */
3775 /* Initialize the information structure for the function. */
3784 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3785 properly copied out by the return statement. We do this by making a new
3786 block and converting any return into a goto to a label at the end of the
3787 block. */
3789 {
3798 /* If this is a function with copy-in/copy-out parameters and which does
3799 not return by invisible reference, we also need a variable for the
3800 return value to be placed. */
3802 {
3803 tree gnu_return_type
3806 gnu_return_var
3812 }
3816 /* See whether there are parameters for which we don't have a GCC tree
3817 yet. These must be Out parameters. Make a VAR_DECL for them and
3818 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3819 We can match up the entries because TYPE_CI_CO_LIST is in the order
3820 of the parameters. */
3825 {
3827 tree gnu_decl;
3829 /* Skip any entries that have been already filled in; they must
3830 correspond to In Out parameters. */
3834 /* Do any needed dereferences for by-ref objects. */
3840 /* Do any needed references for padded types. */
3843 }
3844 }
3845 else
3848 /* Get a tree corresponding to the code for the subprogram. */
3854 /* Generate the code of the subprogram itself. A return statement will be
3855 present and any Out parameters will be handled there. */
3860 /* If we populated the parameter attributes cache, we need to make sure that
3861 the cached expressions are evaluated on all the possible paths leading to
3862 their uses. So we force their evaluation on entry of the function. */
3865 {
3872 {
3879 }
3885 }
3887 /* If we are dealing with a return from an Ada procedure with parameters
3888 passed by copy-in/copy-out, we need to return a record containing the
3889 final values of these parameters. If the list contains only one entry,
3890 return just that entry though.
3892 For a full description of the copy-in/copy-out parameter mechanism, see
3893 the part of the gnat_to_gnu_entity routine dealing with the translation
3894 of subprograms.
3896 We need to make a block that contains the definition of that label and
3897 the copying of the return value. It first contains the function, then
3898 the label and copy statement. */
3900 {
3901 const Node_Id gnat_end_label
3910 /* If this is a function which returns by invisible reference, the
3911 return value has already been dealt with at the return statements,
3912 so we only need to indirectly copy out the parameters. */
3914 {
3915 tree gnu_ret_deref
3917 tree t;
3922 {
3923 tree gnu_field_deref
3928 }
3929 }
3931 /* Otherwise, if this is a procedure or a function which does not return
3932 by invisible reference, we can do a direct block-copy out. */
3933 else
3934 {
3935 tree gnu_retval;
3939 else
3940 gnu_retval
3942 gnu_cico_list);
3946 }
3950 }
3954 /* Attempt setting the end_locus of our GCC body tree, typically a
3955 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3956 declaration tree. */
3960 /* On SEH targets, install an exception handler around the main entry
3961 point to catch unhandled exceptions. */
3964 {
3965 tree t;
3966 tree etype;
3978 }
3982 /* Finally annotate the parameters and disconnect the trees for parameters
3983 that we have turned into variables since they are now unusable. */
3987 {
3996 }
3998 /* Disconnect the variable created for the return value. */
4002 /* If the function returns an aggregate type and we have candidates for
4003 a Named Return Value, finalize the optimization. */
4005 {
4012 }
4014 /* If this is an inlined external function that has been marked uninlinable,
4015 drop the body and stop there. Otherwise compile the body. */
4018 else
4020 }
4021 \f
4022 /* Return true if GNAT_NODE references an Atomic entity. */
4024 static bool
4026 {
4027 Entity_Id gnat_entity;
4030 {
4049 /* ... fall through ... */
4056 }
4059 }
4061 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. */
4063 static bool
4065 {
4066 Entity_Id gnat_entity;
4069 {
4089 }
4092 }
4094 /* Strip any type conversion on GNAT_NODE and return the result. */
4096 static Node_Id
4098 {
4105 }
4107 /* Return true if GNAT_NODE requires outer atomic access, i.e. atomic access
4108 of an object of which GNAT_NODE is a component. */
4110 static bool
4112 {
4116 {
4118 {
4123 gnat_node
4137 }
4138 }
4141 }
4143 /* Return true if GNAT_NODE requires atomic access and set SYNC according to
4144 the associated synchronization setting. */
4146 static bool
4148 {
4153 /* First, scan the parent to find out cases where the flag is irrelevant. */
4155 {
4158 /* Do not mess up machine code insertions. */
4162 /* Nothing to do if we are the prefix of an attribute, since we do not
4163 want an atomic access for things like 'Size. */
4165 /* ... fall through ... */
4168 /* The N_Reference node is like an attribute. */
4176 /* If we are the prefix, then the access is only partial. */
4182 /* Nothing to do for the identifier in an object renaming declaration,
4183 the renaming itself does not need atomic access. */
4188 }
4190 /* Then, scan the node to find the atomic object. */
4193 /* For Atomic itself, only reads and updates of the object as a whole require
4194 atomic access (RM C.6 (15)). But for Volatile_Full_Access, all reads and
4195 updates require atomic access. */
4200 /* If an outer atomic access will also be required, it cancels this one. */
4207 }
4208 \f
4209 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4211 static tree
4213 {
4214 tree gnu_temp
4220 }
4222 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4223 Put the initialization statement into GNU_INIT_STMT and annotate it with
4224 the SLOC of GNAT_NODE. Return the temporary variable. */
4226 static tree
4228 Node_Id gnat_node)
4229 {
4236 }
4238 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
4239 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4240 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4241 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4242 N_Assignment_Statement and the result is to be placed into that object.
4243 If OUTER_ATOMIC_ACCESS is true, then the assignment to GNU_TARGET must be a
4244 load-modify-store sequence. Otherwise, if ATOMIC_ACCESS is true, then the
4245 assignment to GNU_TARGET must be atomic. If, in addition, ATOMIC_SYNC is
4246 true, then the assignment to GNU_TARGET requires atomic synchronization. */
4248 static tree
4251 {
4254 /* The GCC node corresponding to the GNAT subprogram name. This can either
4255 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4256 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4257 subprogram. */
4259 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4261 /* The return type of the FUNCTION_TYPE. */
4273 Entity_Id gnat_formal;
4274 Node_Id gnat_actual;
4279 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4280 all our args first. */
4282 {
4292 {
4295 }
4298 }
4300 /* For a call to a nested function, check the inlining status. */
4305 /* The only way we can be making a call via an access type is if Name is an
4306 explicit dereference. In that case, get the list of formal args from the
4307 type the access type is pointing to. Otherwise, get the formals from the
4308 entity being called. */
4310 {
4313 /* If the access type doesn't require foreign-compatible representation,
4314 be prepared for descriptors. */
4318 }
4320 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4322 else
4325 /* The lifetime of the temporaries created for the call ends right after the
4326 return value is copied, so we can give them the scope of the elaboration
4327 routine at top level. */
4329 {
4332 }
4334 /* First, create the temporary for the return value when:
4336 1. There is no target and the function has copy-in/copy-out parameters,
4337 because we need to preserve the return value before copying back the
4338 parameters.
4340 2. There is no target and the call is made for neither an object nor a
4341 renaming declaration, nor a return statement, and the return type has
4342 variable size, because in this case the gimplifier cannot create the
4343 temporary, or more generally is simply an aggregate type, because the
4344 gimplifier would create the temporary in the outermost scope instead
4345 of locally.
4347 3. There is a target and it is a slice or an array with fixed size,
4348 and the return type has variable size, because the gimplifier
4349 doesn't handle these cases.
4351 4. There is no target and we have misaligned In Out or Out parameters
4352 passed by reference, because we need to preserve the return value
4353 before copying back the parameters. However, in this case, we'll
4354 defer creating the temporary, see below.
4356 This must be done before we push a binding level around the call, since
4357 we will pop it before copying the return value. */
4360 || (!gnu_target
4366 || (gnu_target
4372 {
4375 }
4377 /* If we don't need a value or have already created it, push a binding level
4378 around the call. This will narrow the lifetime of the temporaries we may
4379 need to make when translating the parameters as much as possible. */
4381 {
4385 }
4387 /* Create the list of the actual parameters as GCC expects it, namely a
4388 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4389 is an expression and the TREE_PURPOSE field is null. But skip Out
4390 parameters not passed by reference and that need not be copied in. */
4395 {
4400 const bool is_true_formal_parm
4402 const bool is_by_ref_formal_parm
4403 = is_true_formal_parm
4406 /* In the Out or In Out case, we must suppress conversions that yield
4407 an lvalue but can nevertheless cause the creation of a temporary,
4408 because we need the real object in this case, either to pass its
4409 address if it's passed by reference or as target of the back copy
4410 done after the call if it uses the copy-in/copy-out mechanism.
4411 We do it in the In case too, except for an unchecked conversion
4412 to an elementary type or a constrained composite type because it
4413 alone can cause the actual to be misaligned and the addressability
4414 test is applied to the real object. */
4415 const bool suppress_type_conversion
4422 Node_Id gnat_name = suppress_type_conversion
4426 /* If it's possible we may need to use this expression twice, make sure
4427 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4428 to force side-effects before the call. */
4430 {
4434 gnu_name
4436 }
4438 /* If we are passing a non-addressable parameter by reference, pass the
4439 address of a copy. In the Out or In Out case, set up to copy back
4440 out after the call. */
4444 {
4448 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4449 but sort of an instantiation for them. */
4451 ;
4453 /* If the type is passed by reference, a copy is not allowed. */
4456 gnat_actual);
4458 /* For users of Starlet we issue a warning because the interface
4459 apparently assumes that by-ref parameters outlive the procedure
4460 invocation. The code still will not work as intended, but we
4461 cannot do much better since low-level parts of the back-end
4462 would allocate temporaries at will because of the misalignment
4463 if we did not do so here. */
4465 {
4466 post_error
4468 post_error_ne
4472 gnat_formal);
4473 }
4475 /* If the actual type of the object is already the nominal type,
4476 we have nothing to do, except if the size is self-referential
4477 in which case we'll remove the unpadding below. */
4480 ;
4482 /* Otherwise remove the unpadding from all the objects. */
4484 && TYPE_IS_PADDING_P
4488 /* Otherwise convert to the nominal type of the object if needed.
4489 There are several cases in which we need to make the temporary
4490 using this type instead of the actual type of the object when
4491 they are distinct, because the expectations of the callee would
4492 otherwise not be met:
4493 - if it's a justified modular type,
4494 - if the actual type is a smaller form of it,
4495 - if it's a smaller form of the actual type. */
4499 gnu_name_type)))
4505 /* If this is an In Out or Out parameter and we're returning a value,
4506 we need to create a temporary for the return value because we must
4507 preserve it before copying back at the very end. */
4509 {
4512 }
4514 /* If we haven't pushed a binding level, push it now. This will
4515 narrow the lifetime of the temporary we are about to make as
4516 much as possible. */
4518 {
4522 }
4524 /* Create an explicit temporary holding the copy. */
4525 gnu_temp
4528 /* But initialize it on the fly like for an implicit temporary as
4529 we aren't necessarily having a statement list. */
4531 gnu_temp);
4533 /* Set up to move the copy back to the original if needed. */
4535 {
4536 /* If the original is a COND_EXPR whose first arm isn't meant to
4537 be further used, just deal with the second arm. This is very
4538 likely the conditional expression built for a check. */
4541 && integer_zerop
4545 gnu_stmt
4550 }
4551 }
4553 /* Start from the real object and build the actual. */
4556 /* If atomic access is required for an In or In Out actual parameter,
4557 build the atomic load. */
4559 && !is_by_ref_formal_parm
4564 /* If this was a procedure call, we may not have removed any padding.
4565 So do it here for the part we will use as an input, if any. */
4568 gnu_actual
4571 /* Put back the conversion we suppressed above in the computation of the
4572 real object. And even if we didn't suppress any conversion there, we
4573 may have suppressed a conversion to the Etype of the actual earlier,
4574 since the parent is a procedure call, so put it back here. Note that
4575 we might have a dummy type here if the actual is the dereference of a
4576 pointer to it, but that's OK if the formal is passed by reference. */
4584 else
4587 /* Make sure that the actual is in range of the formal's type. */
4590 gnu_actual
4593 /* Unless this is an In parameter, we must remove any justified modular
4594 building from GNU_NAME to get an lvalue. */
4599 gnu_name
4602 /* First see if the parameter is passed by reference. */
4604 {
4606 {
4607 /* In Out or Out parameters passed by reference don't use the
4608 copy-in/copy-out mechanism so the address of the real object
4609 must be passed to the function. */
4612 /* If we have a padded type, be sure we've removed padding. */
4615 gnu_actual);
4617 /* If we have the constructed subtype of an aliased object
4618 with an unconstrained nominal subtype, the type of the
4619 actual includes the template, although it is formally
4620 constrained. So we need to convert it back to the real
4621 constructed subtype to retrieve the constrained part
4622 and takes its address. */
4628 gnu_actual);
4629 }
4631 /* There is no need to convert the actual to the formal's type before
4632 taking its address. The only exception is for unconstrained array
4633 types because of the way we build fat pointers. */
4635 {
4636 /* Put back a view conversion for In Out or Out parameters. */
4639 gnu_actual);
4641 }
4643 /* The symmetry of the paths to the type of an entity is broken here
4644 since arguments don't know that they will be passed by ref. */
4647 }
4649 /* Then see if the parameter is an array passed to a foreign convention
4650 subprogram. */
4652 {
4658 {
4661 }
4663 /* Take the address of the object and convert to the proper pointer
4664 type. We'd like to actually compute the address of the beginning
4665 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4666 possibility that the ARRAY_REF might return a constant and we'd be
4667 getting the wrong address. Neither approach is exactly correct,
4668 but this is the most likely to work in all cases. */
4670 }
4672 /* Otherwise the parameter is passed by copy. */
4673 else
4674 {
4675 tree gnu_size;
4680 /* If we didn't create a PARM_DECL for the formal, this means that
4681 it is an Out parameter not passed by reference and that need not
4682 be copied in. In this case, the value of the actual need not be
4683 read. However, we still need to make sure that its side-effects
4684 are evaluated before the call, so we evaluate its address. */
4686 {
4688 {
4691 }
4693 }
4697 /* If this is 'Null_Parameter, pass a zero even though we are
4698 dereferencing it. */
4704 {
4705 tree type_for_size
4707 gnu_actual
4711 }
4712 else
4714 }
4717 }
4719 gnu_call
4724 /* If we have created a temporary for the return value, initialize it. */
4726 {
4727 tree gnu_stmt
4732 }
4734 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4735 unpack the valued returned from the function into the In Out or Out
4736 parameters. We deal with the function return (if this is an Ada
4737 function) below. */
4739 {
4740 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4741 copy-out parameters. */
4745 /* The call sequence must contain one and only one call, even though the
4746 function is pure. Save the result into a temporary if needed. */
4748 {
4750 {
4751 tree gnu_stmt;
4752 gnu_call
4755 }
4758 }
4760 /* The first entry is for the actual return value if this is a
4761 function, so skip it. */
4767 else
4774 /* If we are dealing with a copy-in/copy-out parameter, we must
4775 retrieve its value from the record returned in the call. */
4781 {
4782 /* Get the value to assign to this Out or In Out parameter. It is
4783 either the result of the function if there is only a single such
4784 parameter or the appropriate field from the record returned. */
4785 tree gnu_result
4787 ? gnu_call
4791 /* If the actual is a conversion, get the inner expression, which
4792 will be the real destination, and convert the result to the
4793 type of the actual parameter. */
4794 tree gnu_actual
4797 /* If the result is a padded type, remove the padding. */
4799 gnu_result
4801 gnu_result);
4803 /* If the actual is a type conversion, the real target object is
4804 denoted by the inner Expression and we need to convert the
4805 result to the associated type.
4806 We also need to convert our gnu assignment target to this type
4807 if the corresponding GNU_NAME was constructed from the GNAT
4808 conversion node and not from the inner Expression. */
4810 {
4811 gnu_result
4812 = convert_with_check
4820 }
4822 /* Unchecked conversions as actuals for Out parameters are not
4823 allowed in user code because they are not variables, but do
4824 occur in front-end expansions. The associated GNU_NAME is
4825 always obtained from the inner expression in such cases. */
4828 gnu_result,
4830 else
4831 {
4833 gnu_result
4835 gnat_actual);
4840 }
4842 /* If an outer atomic access is required for an actual parameter,
4843 build the load-modify-store sequence. */
4845 gnu_result
4848 /* Or else, if simple atomic access is required, build the atomic
4849 store. */
4853 /* Otherwise build a regular assignment. */
4854 else
4863 }
4864 }
4866 /* If this is a function call, the result is the call expression unless a
4867 target is specified, in which case we copy the result into the target
4868 and return the assignment statement. */
4870 {
4871 /* If this is a function with copy-in/copy-out parameters, extract the
4872 return value from it and update the return type. */
4874 {
4876 gnu_call
4879 }
4881 /* If the function returns an unconstrained array or by direct reference,
4882 we have to dereference the pointer. */
4888 {
4892 /* If range check is needed, emit code to generate it. */
4894 gnu_call
4896 gnat_parent);
4898 /* ??? If the return type has variable size, then force the return
4899 slot optimization as we would not be able to create a temporary.
4900 That's what has been done historically. */
4903 else
4906 /* Use the required method to move the result to the target. */
4908 gnu_call
4912 else
4913 gnu_call
4919 }
4920 else
4922 }
4924 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4925 parameters, the result is just the call statement. */
4929 /* Finally, add the copy back statements, if any. */
4935 /* If we have pushed a binding level, pop it and finish up the enclosing
4936 statement group. */
4938 {
4942 }
4944 /* Otherwise, retrieve the statement list, if any. */
4948 /* Otherwise, just return the call expression. */
4949 else
4952 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4953 But first simplify if we have only one statement in the list. */
4955 {
4959 gnu_result
4961 }
4964 }
4965 \f
4966 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4967 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4969 static tree
4971 {
4974 /* If just annotating, ignore all EH and cleanups. */
4978 bool fe_sjlj
4984 tree gnu_result;
4985 tree gnu_expr;
4986 Node_Id gnat_temp;
4988 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4989 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4990 add_cleanup, and when we leave the binding, end_stmt_group will create
4991 the TRY_FINALLY_EXPR.
4993 ??? The region level calls down there have been specifically put in place
4994 for a ZCX context and currently the order in which things are emitted
4995 (region/handlers) is different from the SJLJ case. Instead of putting
4996 other calls with different conditions at other places for the SJLJ case,
4997 it seems cleaner to reorder things for the SJLJ case and generalize the
4998 condition to make it not ZCX specific.
5000 If there are any exceptions or cleanup processing involved, we need an
5001 outer statement group (for Fe_Sjlj) and binding level. */
5003 {
5006 }
5008 /* If using fe_sjlj, make the variables for the setjmp buffer and save
5009 area for address of previous buffer. Do this first since we need to have
5010 the setjmp buf known for any decls in this block. */
5012 {
5013 gnu_jmpsave_decl
5015 jmpbuf_ptr_type,
5020 /* The __builtin_setjmp receivers will immediately reinstall it. Now
5021 because of the unstructured form of EH used by fe_sjlj, there
5022 might be forward edges going to __builtin_setjmp receivers on which
5023 it is uninitialized, although they will never be actually taken. */
5025 gnu_jmpbuf_decl
5027 jmpbuf_type,
5028 NULL_TREE,
5034 /* When we exit this block, restore the saved value. */
5038 }
5040 /* If we are to call a function when exiting this block, add a cleanup
5041 to the binding level we made above. Note that add_cleanup is FIFO
5042 so we must register this cleanup after the EH cleanup just above. */
5044 {
5047 /* When not optimizing, disable inlining of finalizers as this can
5048 create a more complex CFG in the parent function. */
5052 /* If there is no end label attached, we use the location of the At_End
5053 procedure because Expand_Cleanup_Actions might reset the location of
5054 the enclosing construct to that of an inner statement. */
5058 }
5060 /* Now build the tree for the declarations and statements inside this block.
5061 If this is SJLJ, set our jmp_buf as the current buffer. */
5065 {
5068 gnu_jmpbuf_decl));
5071 }
5077 /* Generate code for each statement in the block. */
5085 /* Now generate code for the two exception models, if either is relevant for
5086 this block. */
5088 {
5090 tree gnu_handler;
5092 /* Make a binding level for the exception handling declarations and code
5093 and set up gnu_except_ptr_stack for the handlers to use. */
5104 /* Generate code for each handler. The N_Exception_Handler case does the
5105 real work and returns a COND_EXPR for each handler, which we chain
5106 together here. */
5109 {
5112 /* If this is the first one, set it as the outer one. Otherwise,
5113 point the "else" part of the previous handler to us. Then point
5114 to our "else" part. */
5117 else
5121 }
5123 /* If none of the exception handlers did anything, re-raise but do not
5124 defer abortion. */
5127 set_expr_location_from_node
5133 else
5136 /* End the binding level dedicated to the exception handlers and get the
5137 whole statement group. */
5142 /* If the setjmp returns 1, we restore our incoming longjmp value and
5143 then check the handlers. */
5146 gnu_jmpsave_decl),
5147 gnat_node);
5151 /* This block is now "if (setjmp) ... <handlers> else <block>". */
5153 (build_call_n_expr
5156 gnu_jmpbuf_decl))),
5158 }
5160 {
5161 tree gnu_handlers;
5162 location_t locus;
5164 /* First make a block containing the handlers. */
5172 /* Now make the TRY_CATCH_EXPR for the block. */
5175 /* Set a location. We need to find a unique location for the dispatching
5176 code, otherwise we can get coverage or debugging issues. Try with
5177 the location of the end label. */
5181 else
5182 /* Clear column information so that the exception handler of an
5183 implicit transient block does not incorrectly inherit the slocs
5184 of a decision, which would otherwise confuse control flow based
5185 coverage analysis tools. */
5187 }
5188 else
5191 /* Now close our outer block, if we had to make one. */
5193 {
5197 }
5200 }
5201 \f
5202 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5203 to a GCC tree, which is returned. This is the variant for front-end sjlj
5204 exception handling. */
5206 static tree
5208 {
5209 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
5210 an "if" statement to select the proper exceptions. For "Others", exclude
5211 exceptions where Handled_By_Others is nonzero unless the All_Others flag
5212 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
5215 Node_Id gnat_temp;
5219 {
5220 tree this_choice;
5223 {
5226 else
5227 this_choice
5228 = build_binary_op
5230 convert
5232 build_component_ref
5233 (build_unary_op
5236 not_handled_by_others_decl,
5238 integer_zero_node);
5239 }
5243 {
5245 tree gnu_expr;
5247 /* Exception may be a renaming. Recover original exception which is
5248 the one elaborated and registered. */
5254 this_choice
5255 = build_binary_op
5260 }
5261 else
5266 }
5269 }
5270 \f
5271 /* Return true if no statement in GNAT_LIST can alter the control flow. */
5273 static bool
5275 {
5279 /* This is very conservative, we reject everything except for simple
5280 assignments between identifiers or literals. */
5284 {
5296 }
5299 }
5301 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5302 to a GCC tree, which is returned. This is the variant for GCC exception
5303 schemes. */
5305 static tree
5307 {
5310 /* We build a TREE_LIST of nodes representing what exception types this
5311 handler can catch, with special cases for others and all others cases.
5313 Each exception type is actually identified by a pointer to the exception
5314 id, or to a dummy object for "others" and "all others". */
5316 gnat_temp;
5318 {
5322 {
5325 }
5328 {
5331 /* Exception may be a renaming. Recover original exception which is
5332 the one elaborated and registered. */
5338 }
5339 else
5342 /* The GCC interface expects NULL to be passed for catch all handlers, so
5343 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5344 is integer_zero_node. It would not work, however, because GCC's
5345 notion of "catch all" is stronger than our notion of "others". Until
5346 we correctly use the cleanup interface as well, doing that would
5347 prevent the "all others" handlers from being seen, because nothing
5348 can be caught beyond a catch all from GCC's point of view. */
5350 }
5355 /* Expand a call to the begin_handler hook at the beginning of the handler,
5356 and arrange for a call to the end_handler hook to occur on every possible
5357 exit path.
5359 The hooks expect a pointer to the low level occurrence. This is required
5360 for our stack management scheme because a raise inside the handler pushes
5361 a new occurrence on top of the stack, which means that this top does not
5362 necessarily match the occurrence this handler was dealing with.
5364 __builtin_eh_pointer references the exception occurrence being
5365 propagated. Upon handler entry, this is the exception for which the
5366 handler is triggered. This might not be the case upon handler exit,
5367 however, as we might have a new occurrence propagated by the handler's
5368 body, and the end_handler hook called as a cleanup in this context.
5370 We use a local variable to retrieve the incoming value at handler entry
5371 time, and reuse it to feed the end_handler hook's argument at exit. */
5373 tree gnu_current_exc_ptr
5377 gnu_incoming_exc_ptr
5384 gnu_incoming_exc_ptr),
5385 gnat_node);
5387 /* Declare and initialize the choice parameter, if present. */
5389 {
5390 tree gnu_param
5396 gnu_incoming_exc_ptr));
5397 }
5401 /* We don't have an End_Label at hand to set the location of the cleanup
5402 actions, so we use that of the exception handler itself instead. */
5406 else
5413 return
5415 }
5416 \f
5417 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5419 static void
5421 {
5426 Entity_Id gnat_entity;
5427 Node_Id gnat_pragma;
5428 /* Make the decl for the elaboration procedure. Emit debug info for it, so
5429 that users can break into their elaboration code in debuggers. Kludge:
5430 don't consider it as a definition so that we have a line map for its body,
5431 but no subprogram description in debug info. */
5432 tree gnu_elab_proc_decl
5433 = create_subprog_decl
5442 /* Initialize the information structure for the function. */
5451 /* For a body, first process the spec if there is one. */
5457 {
5464 }
5466 /* Then process any pragmas and declarations preceding the unit. */
5475 /* Process the unit itself. */
5478 /* Generate code for all the inlined subprograms. */
5482 {
5483 Node_Id gnat_body;
5485 /* Without optimization, process only the required subprograms. */
5489 /* The set of inlined subprograms is computed from data recorded early
5490 during expansion and it can be a strict superset of the final set
5491 computed after semantic analysis, for example if a call to such a
5492 subprogram occurs in a pragma Assert and assertions are disabled.
5493 In that case, semantic analysis resets Is_Public to false but the
5494 entry for the subprogram in the inlining tables is stalled. */
5500 {
5501 /* ??? This happens when only the spec of a package is provided. */
5505 gnat_body
5507 }
5509 /* Define the entity first so we set DECL_EXTERNAL. */
5512 }
5514 /* Process any pragmas and actions following the unit. */
5519 /* Save away what we've made so far and finish it up. */
5526 /* Record this potential elaboration procedure for later processing. */
5533 /* Force the processing for all nodes that remain in the queue. */
5535 }
5536 \f
5537 /* Mark COND, a boolean expression, as predicating a call to a noreturn
5538 function, i.e. predict that it is very likely false, and return it.
5540 The compiler will automatically predict the last edge leading to a call
5541 to a noreturn function as very unlikely taken. This function makes it
5542 possible to expand the prediction to predecessors in case the condition
5543 is made up of several short-circuit operators. */
5545 static tree
5547 {
5557 PRED_NORETURN));
5560 }
5562 /* Subroutine of gnat_to_gnu to translate GNAT_RANGE, a node representing a
5563 range of values, into GNU_LOW and GNU_HIGH bounds. */
5565 static void
5567 {
5568 /* GNAT_RANGE is either an N_Range or an identifier denoting a subtype. */
5570 {
5578 {
5582 *gnu_low
5584 *gnu_high
5586 }
5591 }
5592 }
5594 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Raise_xxx_Error,
5595 to a GCC tree and return it. GNU_RESULT_TYPE_P is a pointer to where
5596 we should place the result type. */
5598 static tree
5600 {
5604 const bool with_extra_info
5605 = Exception_Extra_Info
5610 /* The following processing is not required for correctness. Its purpose is
5611 to give more precise error messages and to record some information. */
5613 {
5623 {
5630 {
5648 }
5656 {
5662 }
5665 && gnu_low_bound
5666 && gnu_high_bound
5669 gnu_result
5673 /* If optimization is enabled and we are inside a loop, we try to
5674 compute invariant conditions for checks applied to the iteration
5675 variable, i.e. conditions that are independent of the variable
5676 and necessary in order for the checks to fail in the course of
5677 some iteration. If we succeed, we consider an alternative:
5679 1. If loop unswitching is enabled, we prepend these conditions
5680 to the original conditions of the checks. This will make it
5681 possible for the loop unswitching pass to replace the loop
5682 with two loops, one of which has the checks eliminated and
5683 the other has the original checks reinstated, and a prologue
5684 implementing a run-time selection. The former loop will be
5685 for example suitable for vectorization.
5687 2. Otherwise, we instead append the conditions to the original
5688 conditions of the checks. At worse, if the conditions cannot
5689 be evaluated at compile time, they will be evaluated as true
5690 at run time only when the checks have already failed, thus
5691 contributing negatively only to the size of the executable.
5692 But the hope is that these invariant conditions be evaluated
5693 at compile time to false, thus taking away the entire checks
5694 with them. */
5697 && (!gnu_low_bound
5699 && (!gnu_high_bound
5702 {
5709 rci->inserted_cond
5716 boolean_type_node,
5718 gnu_cond);
5719 else
5721 boolean_type_node,
5722 gnu_cond,
5724 }
5726 /* Or else, if aggressive loop optimizations are enabled, we just
5727 record that there are checks applied to iteration variables. */
5729 && flag_aggressive_loop_optimizations
5733 }
5738 }
5740 /* The following processing does the common work. */
5741 common:
5748 /* If the type is VOID, this is a statement, so we need to generate the code
5749 for the call. Handle a condition, if there is one. */
5751 {
5753 {
5758 }
5759 }
5760 else
5764 }
5765 \f
5766 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5767 parameter of a call. */
5769 static bool
5771 {
5786 }
5788 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5789 of an assignment or an actual parameter of a call. */
5791 static bool
5793 {
5794 Node_Kind kind;
5806 }
5808 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5809 as gigi is concerned. This is used to avoid conversions on the LHS. */
5811 static bool
5813 {
5816 /* The conversion must be on the LHS of an assignment or an actual parameter
5817 of a call. Otherwise, even if the conversion was essentially a no-op, it
5818 could de facto ensure type consistency and this should be preserved. */
5824 /* We're interested in artificial conversions generated by the front-end
5825 to make private types explicit, e.g. in Expand_Assign_Array. */
5832 /* The direct conversion to the underlying type is a no-op. */
5836 /* For an array subtype, the conversion to the PAIT is a no-op. */
5841 /* For a record subtype, the conversion to the type is a no-op. */
5847 }
5849 /* Return true if GNAT_NODE represents a statement. */
5851 static bool
5853 {
5869 }
5871 /* This function is the driver of the GNAT to GCC tree transformation process.
5872 It is the entry point of the tree transformer. GNAT_NODE is the root of
5873 some GNAT tree. Return the root of the corresponding GCC tree. If this
5874 is an expression, return the GCC equivalent of the expression. If this
5875 is a statement, return the statement or add it to the current statement
5876 group, in which case anything returned is to be interpreted as occurring
5877 after anything added. */
5879 tree
5881 {
5887 Node_Id gnat_temp;
5890 /* Save node number for error message and set location information. */
5894 /* If we are only annotating types and this node is a statement, return
5895 an empty statement list. */
5899 /* If we are only annotating types and this node is a subexpression, return
5900 a NULL_EXPR, but filter out nodes appearing in the expressions attached
5901 to packed array implementation types. */
5916 N_Raise_Constraint_Error));
5921 {
5924 /* If this is a statement and we are at top level, it must be part of
5925 the elaboration procedure, so mark us as being in that procedure. */
5927 {
5930 }
5932 /* If we are in the elaboration procedure, check if we are violating a
5933 No_Elaboration_Code restriction by having a statement there. Don't
5934 check for a possible No_Elaboration_Code restriction violation on
5935 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5936 every nested real statement instead. This also avoids triggering
5937 spurious errors on dummy (empty) sequences created by the front-end
5938 for package bodies in some cases. */
5943 }
5946 {
5947 /********************************/
5948 /* Chapter 2: Lexical Elements */
5949 /********************************/
5958 /* If atomic access is required on the RHS, build the atomic load. */
5965 {
5966 tree gnu_type;
5968 /* Get the type of the result, looking inside any padding and
5969 justified modular types. Then get the value in that type. */
5978 /* If the result overflows (meaning it doesn't fit in its base type),
5979 abort. We would like to check that the value is within the range
5980 of the subtype, but that causes problems with subtypes whose usage
5981 will raise Constraint_Error and with biased representation, so
5982 we don't. */
5984 }
5988 /* If a Entity is present, it means that this was one of the
5989 literals in a user-defined character type. In that case,
5990 just return the value in the CONST_DECL. Otherwise, use the
5991 character code. In that case, the base type should be an
5992 INTEGER_TYPE, but we won't bother checking for that. */
5996 else
5997 gnu_result
6005 /* If this is of a fixed-point type, the value we want is the value of
6006 the corresponding integer. */
6008 {
6010 gnu_result_type);
6012 }
6014 else
6015 {
6018 /* First convert the value to a machine number if it isn't already.
6019 That will force the base to 2 for non-zero values and simplify
6020 the rest of the logic. */
6022 ur_realval
6028 else
6029 {
6030 REAL_VALUE_TYPE tmp;
6034 /* The base must be 2 as Machine guarantees this, so we scale
6035 the value, which we know can fit in the mantissa of the type
6036 (hence the use of that type above). */
6041 }
6043 /* Now see if we need to negate the result. Do it this way to
6044 properly handle -0. */
6046 gnu_result
6048 gnu_result);
6049 }
6056 {
6063 else
6066 /* Build the string with the characters in the literal. Note
6067 that Ada strings are 1-origin. */
6071 /* Put a null at the end of the string in case it's in a context
6072 where GCC will want to treat it as a C string. */
6077 /* Strings in GCC don't normally have types, but we want
6078 this to not be converted to the array type. */
6083 }
6084 else
6085 {
6086 /* Build a list consisting of each character, then make
6087 the aggregate. */
6097 {
6103 }
6106 }
6113 /**************************************/
6114 /* Chapter 3: Declarations and Types */
6115 /**************************************/
6132 /* If we are just annotating types and this object has an unconstrained
6133 or task type, don't elaborate it. */
6143 && (!type_annotate_only
6145 {
6148 gnu_expr
6153 }
6154 else
6157 /* If this is a deferred constant with an address clause, we ignore the
6158 full view since the clause is on the partial view and we cannot have
6159 2 different GCC trees for the object. The only bits of the full view
6160 we will use is the initializer, but it will be directly fetched. */
6166 /* If this object has its elaboration delayed, we must force evaluation
6167 of GNU_EXPR now and save it for the freeze point. Note that we need
6168 not do anything special at the global level since the lifetime of the
6169 temporary is fully contained within the elaboration routine. */
6171 {
6173 {
6176 }
6177 }
6178 else
6186 /* Don't do anything if this renaming is handled by the front end and it
6187 does not need debug info. Note that we consider renamings don't need
6188 debug info when optimizing: our way to describe them has a
6189 memory/elaboration footprint.
6191 Don't do anything neither if we are just annotating types and this
6192 object has a composite or task type, don't elaborate it. */
6195 && !optimize
6196 && can_materialize_object_renaming_p
6198 && ! (type_annotate_only
6202 {
6203 tree gnu_temp
6207 /* See case 2 of renaming in gnat_to_gnu_entity. */
6210 }
6217 /* See the above case for the rationale. */
6219 {
6220 tree gnu_temp
6226 }
6230 {
6236 /* Materializing renamed subprograms will only benefit the debugging
6237 information as they aren't referenced in the generated code. So
6238 skip them when they aren't needed. Avoid doing this if:
6240 - there is a freeze node: in this case the renamed entity is not
6241 elaborated yet,
6242 - the renamed subprogram is intrinsic: it will not be available in
6243 the debugging information (note that both or only one of the
6244 renaming and the renamed subprograms can be intrinsic). */
6255 }
6264 /* These are fully handled in the front end. */
6265 /* ??? For package renamings, find a way to use GENERIC namespaces so
6266 that we get proper debug information for them. */
6270 /*************************************/
6271 /* Chapter 4: Names and Expressions */
6272 /*************************************/
6279 /* If atomic access is required on the RHS, build the atomic load. */
6286 {
6288 tree gnu_type;
6295 /* Convert vector inputs to their representative array type, to fit
6296 what the code below expects. */
6298 {
6302 }
6306 /* If we got a padded type, remove it too. */
6308 gnu_array_object
6310 gnu_array_object);
6312 /* The failure of this assertion will very likely come from a missing
6313 expansion for a packed array access. */
6316 /* First compute the number of dimensions of the array, then
6317 fill the expression array, the order depending on whether
6318 this is a Convention_Fortran array or not. */
6323 ;
6332 else
6338 /* Start with the prefix and build the successive references. */
6344 {
6350 gnu_result
6353 /* Array accesses are bound-checked so they cannot trap, but this
6354 is valid only if they are not hoisted ahead of the check. We
6355 need to mark them as no-trap to get decent loop optimizations
6356 in the presence of -fnon-call-exceptions, so we do it when we
6357 know that the original expression had no side-effects. */
6363 /* If aggressive loop optimizations are enabled, we warn for loops
6364 overrunning a simple array of size 1 not at the end of a record.
6365 This is aimed to catch misuses of the trailing array idiom. */
6367 && flag_aggressive_loop_optimizations
6383 {
6386 }
6387 }
6391 /* If atomic access is required on the RHS, build the atomic load. */
6395 }
6399 {
6410 /* If this is a slice with non-constant size of an array with constant
6411 size, set the maximum size for the allocation of temporaries. */
6419 }
6423 {
6430 /* gnat_to_gnu_entity does not save the GNU tree made for renamed
6431 discriminants so avoid making recursive calls on each reference
6432 to them by following the appropriate link directly here. */
6434 {
6435 /* For discriminant references in tagged types always substitute
6436 the corresponding discriminant as the actual component. */
6441 /* For discriminant references in untagged types always substitute
6442 the corresponding stored discriminant. */
6445 }
6447 /* Handle extracting the real or imaginary part of a complex.
6448 The real part is the first field and the imaginary the last. */
6453 else
6454 {
6457 /* If the prefix has incomplete type, try again to translate it.
6458 The idea is that the translation of the field just above may
6459 have completed it through gnat_to_gnu_entity, in case it is
6460 the dereference of an access to Taft Amendment type used in
6461 the instantiation of a generic body from an external unit. */
6463 {
6466 }
6468 gnu_result
6472 && lvalue_required_for_attribute_p
6474 }
6478 /* If atomic access is required on the RHS, build the atomic load. */
6482 }
6486 {
6487 /* The attribute designator. */
6490 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6491 is a unit, not an object with a GCC equivalent. */
6493 return
6499 gnat_node);
6502 }
6506 /* Like 'Access as far as we are concerned. */
6514 {
6515 tree gnu_aggr_type;
6517 /* ??? It is wrong to evaluate the type now, but there doesn't
6518 seem to be any other practical way of doing it. */
6522 gnu_aggr_type = gnu_result_type
6527 gnu_aggr_type
6537 gnu_result
6540 gnu_aggr_type);
6543 gnu_aggr_type,
6546 gnu_result
6547 = build_binary_op
6552 (Next
6554 else
6558 }
6566 else
6576 /* If this is a qualified expression for a tagged type, we mark the type
6577 as used. Because of polymorphism, this might be the only reference to
6578 the tagged type in the program while objects have it as dynamic type.
6579 The debugger needs to see it to display these objects properly. */
6583 gnu_result
6587 kind == N_Type_Conversion
6595 /* Skip further processing if the conversion is deemed a no-op. */
6597 {
6601 }
6603 /* If the result is a pointer type, see if we are improperly
6604 converting to a stricter alignment. */
6607 {
6613 post_error_ne_tree_2
6617 }
6619 /* If we are converting a descriptor to a function pointer, first
6620 build the pointer. */
6632 {
6641 {
6645 }
6647 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6648 ensure that GNU_OBJ is evaluated only once and perform a full range
6649 test. */
6651 gnu_result
6653 else
6654 {
6663 gnu_result
6665 }
6668 gnu_result
6670 }
6678 ? RDIV_EXPR
6687 /* These can either be operations on booleans or on modular types.
6688 Fall through for boolean types since that's the way GNU_CODES is
6689 set up. */
6691 {
6692 enum tree_code code
6703 }
6705 /* ... fall through ... */
6725 {
6729 tree gnu_type;
6735 /* Pending generic support for efficient vector logical operations in
6736 GCC, convert vectors to their representative array type view and
6737 fallthrough. */
6741 /* If this is a comparison operator, convert any references to an
6742 unconstrained array value into a reference to the actual array. */
6744 {
6750 {
6753 }
6754 }
6756 /* If this is a shift whose count is not guaranteed to be correct,
6757 we need to adjust the shift count. */
6759 {
6761 tree gnu_max_shift
6768 gnu_rhs
6769 = build_binary_op
6772 gnu_count_type,
6773 gnu_max_shift,
6775 gnu_rhs);
6776 }
6778 /* For right shifts, the type says what kind of shift to do,
6779 so we may need to choose a different type. In this case,
6780 we have to ignore integer overflow lest it propagates all
6781 the way down and causes a CE to be explicitly raised. */
6783 {
6786 }
6789 {
6792 }
6795 {
6801 }
6803 /* Instead of expanding overflow checks for addition, subtraction
6804 and multiplication itself, the front end will leave this to
6805 the back end when Backend_Overflow_Checks_On_Target is set. */
6807 && Backend_Overflow_Checks_On_Target
6813 else
6814 {
6815 /* Some operations, e.g. comparisons of arrays, generate complex
6816 trees that need to be annotated while they are being built. */
6819 }
6821 /* If this is a logical shift with the shift count not verified,
6822 we must return zero if it is too large. We cannot compensate
6823 above in this case. */
6826 gnu_result
6827 = build_cond_expr
6830 gnu_rhs,
6834 gnu_result);
6835 }
6839 {
6842 tree gnu_false
6846 gnu_result
6848 }
6857 /* This case can apply to a boolean or a modular type.
6858 Fall through for a boolean operand since GNU_CODES is set
6859 up to handle this. */
6861 {
6865 gnu_expr);
6867 }
6869 /* ... fall through ... */
6876 /* Instead of expanding overflow checks for negation and absolute
6877 value itself, the front end will leave this to the back end
6878 when Backend_Overflow_Checks_On_Target is set. */
6880 && Backend_Overflow_Checks_On_Target
6883 gnu_result
6886 else
6892 {
6894 tree gnu_type;
6899 /* The Expression operand can either be an N_Identifier or
6900 Expanded_Name, which must represent a type, or a
6901 N_Qualified_Expression, which contains both the object type and an
6902 initial value for the object. */
6907 {
6908 Entity_Id gnat_desig_type
6916 gnu_init
6922 else
6923 {
6927 }
6929 /* See the N_Qualified_Expression case for the rationale. */
6934 }
6935 else
6942 ignore_init_type);
6943 }
6946 /**************************/
6947 /* Chapter 5: Statements */
6948 /**************************/
6956 /* When not optimizing, turn null statements from source into gotos to
6957 the next statement that the middle-end knows how to preserve. */
6959 {
6970 }
6971 else
6976 /* Get the LHS and RHS of the statement and convert any reference to an
6977 unconstrained array into a reference to the underlying array. */
6980 /* If the type has a size that overflows, convert this into raise of
6981 Storage_Error: execution shouldn't have gotten here anyway. */
6985 N_Raise_Storage_Error);
6987 {
6988 bool outer_atomic_access
6990 bool atomic_access
6991 = !outer_atomic_access
6993 gnu_result
6996 }
6997 else
6998 {
7000 const Entity_Id gnat_type
7002 const bool regular_array_type_p
7004 const bool use_memset_p
7005 = (regular_array_type_p
7009 /* If we'll use memset, we need to find the inner expression. */
7011 {
7012 Node_Id gnat_inner
7016 gnat_inner
7019 }
7020 else
7023 /* If range check is needed, emit code to generate it. */
7026 gnat_node);
7028 /* If an outer atomic access is required on the LHS, build the load-
7029 modify-store sequence. */
7033 /* Or else, if atomic access is required, build the atomic store. */
7037 /* Or else, use memset when the conditions are met. */
7039 {
7043 tree size
7048 {
7049 tree mask
7053 }
7055 }
7057 /* Otherwise build a regular assignment. */
7058 else
7059 gnu_result
7062 /* If the assignment type is a regular array and the two sides are
7063 not completely disjoint, play safe and use memmove. But don't do
7064 it for a bit-packed array as it might not be byte-aligned. */
7066 && regular_array_type_p
7068 {
7072 tree size
7078 }
7079 }
7083 {
7086 /* Make the outer COND_EXPR. Avoid non-determinism. */
7095 /* Now make a COND_EXPR for each of the "else if" parts. Put each
7096 into the previous "else" part and point to where to put any
7097 outer "else". Also avoid non-determinism. */
7101 {
7111 }
7114 }
7126 /* The only way to enter the block is to fall through to it. */
7128 {
7135 }
7136 else
7141 gnu_result
7151 {
7154 /* If the subprogram is a function, we must return the expression. */
7156 {
7159 /* If this function has copy-in/copy-out parameters parameters and
7160 doesn't return by invisible reference, get the real object for
7161 the return. See Subprogram_Body_to_gnu. */
7165 else
7168 /* Get the GCC tree for the expression to be returned. */
7171 /* Do not remove the padding from GNU_RET_VAL if the inner type is
7172 self-referential since we want to allocate the fixed size. */
7174 && type_is_padding_self_referential
7178 /* If the function returns by direct reference, return a pointer
7179 to the return value. */
7184 /* Otherwise, if it returns an unconstrained array, we have to
7185 allocate a new version of the result and return it. */
7187 {
7190 /* And find out whether this is a candidate for Named Return
7191 Value. If so, record it. */
7193 {
7196 /* Strip useless conversions around the return value. */
7200 /* Strip unpadding around the return value. */
7202 && TYPE_IS_PADDING_P
7206 /* Now apply the test to the return value. */
7208 {
7214 }
7215 }
7218 gnu_ret_val,
7223 }
7225 /* Otherwise, if it returns by invisible reference, dereference
7226 the pointer it is passed using the type of the return value
7227 and build the copy operation manually. This ensures that we
7228 don't copy too much data, for example if the return type is
7229 unconstrained with a maximum size. */
7231 {
7232 tree gnu_ret_deref
7234 gnu_ret_obj);
7239 }
7240 }
7242 else
7245 /* If we have a return label defined, convert this into a branch to
7246 that label. The return proper will be handled elsewhere. */
7248 {
7251 gnu_ret_val));
7256 /* When not optimizing, make sure the return is preserved. */
7259 }
7261 /* Otherwise, build a regular return. */
7262 else
7264 }
7268 gnu_result
7272 /***************************/
7273 /* Chapter 6: Subprograms */
7274 /***************************/
7277 /* Unless there is a freeze node, declare the entity. We consider
7278 this a definition even though we're not generating code for the
7279 subprogram because we will be making the corresponding GCC node.
7280 When there is a freeze node, it is considered the definition of
7281 the subprogram and we do nothing until after it is encountered.
7282 That's an efficiency issue: the types involved in the profile
7283 are far more likely to be frozen between the declaration and
7284 the freeze node than before the declaration, so we save some
7285 updates of the GCC node by waiting until the freeze node.
7286 The counterpart is that we assume that there is no reference
7287 to the subprogram between the declaration and the freeze node
7288 in the expanded code; otherwise, it will be interpreted as an
7289 external reference and very likely give rise to a link failure. */
7297 /* This subprogram doesn't exist for code generation purposes, but we
7298 have to elaborate the types of any parameters and result, unless
7299 they are imported types (nothing to generate in this case).
7301 The parameter list may contain types with freeze nodes, e.g. not null
7302 subtypes, so the subprogram itself may carry a freeze node, in which
7303 case its elaboration must be deferred. */
7305 /* Process the parameter types first. */
7308 = First_Formal_With_Extras
7316 /* Then the result type, set to Standard_Void_Type for procedures. */
7317 {
7318 Entity_Id gnat_temp_type
7323 }
7329 /* For a child unit identifier go up a level to get the specification.
7330 We get this when we try to find the spec of a child unit package
7331 that is the compilation unit being compiled. */
7346 /************************/
7347 /* Chapter 7: Packages */
7348 /************************/
7364 /* If this is the body of a generic package - do nothing. */
7366 {
7369 }
7380 /********************************/
7381 /* Chapter 8: Visibility Rules */
7382 /********************************/
7386 /* Nothing to do here - but these may appear in list of declarations. */
7390 /*********************/
7391 /* Chapter 9: Tasks */
7392 /*********************/
7403 /*********************************************************/
7404 /* Chapter 10: Program Structure and Compilation Issues */
7405 /*********************************************************/
7408 /* This is not called for the main unit on which gigi is invoked. */
7420 /* These nodes should only be present when annotating types. */
7430 /* Simply process whatever unit is being inserted. */
7433 else
7434 {
7437 }
7440 /***************************/
7441 /* Chapter 11: Exceptions */
7442 /***************************/
7445 /* If there is an At_End procedure attached to this node, and the EH
7446 mechanism is front-end, we must have at least a corresponding At_End
7447 handler, unless the No_Exception_Handlers restriction is set. */
7462 else
7467 /* Only for reraise in back-end exceptions mode. */
7474 /* Clear the current exception pointer so that the occurrence won't be
7475 deallocated. */
7515 /******************************/
7516 /* Chapter 12: Generic Units */
7517 /******************************/
7527 /* These nodes can appear on a declaration list but there is nothing to
7528 to be done with them. */
7532 /**************************************************/
7533 /* Chapter 13: Representation Clauses and */
7534 /* Implementation-Dependent Features */
7535 /**************************************************/
7540 /* The only one we need to deal with is 'Address since, for the others,
7541 the front-end puts the information elsewhere. */
7545 /* And we only deal with 'Address if the object has a Freeze node. */
7550 /* Get the value to use as the address and save it as the equivalent
7551 for the object. When it is frozen, gnat_to_gnu_entity will do the
7552 right thing. */
7559 /* We do nothing with these. SEM puts the information elsewhere. */
7565 {
7575 /* First retrieve the 3 operand lists built by the front-end. */
7578 {
7585 }
7589 {
7596 }
7600 gnu_clobbers
7603 gnu_clobbers);
7605 /* Then perform some standard checking and processing on the
7606 operands. In particular, mark them addressable if needed. */
7614 {
7616 constraint
7622 {
7623 /* If the operand is going to end up in memory,
7624 mark it addressable. Note that we don't test
7625 allows_mem like in the input case below; this
7626 is modelled on the C front-end. */
7628 {
7635 }
7636 }
7637 else
7641 }
7644 {
7646 constraint
7652 {
7653 /* If the operand is going to end up in memory,
7654 mark it addressable. */
7656 {
7663 }
7664 }
7665 else
7669 }
7675 }
7676 else
7681 /****************/
7682 /* Added Nodes */
7683 /****************/
7686 /* This construct doesn't define a scope so we don't push a binding
7687 level around the statement list, but we wrap it in a SAVE_EXPR to
7688 protect it from unsharing. Elaborate the expression as part of the
7689 same statement group as the actions so that the type declaration
7690 gets inserted there as well. This ensures that the type elaboration
7691 code is issued past the actions computing values on which it might
7692 depend. */
7701 gnu_result
7725 {
7730 /* If this is a thin pointer, we must first dereference it to create
7731 a fat pointer, then go back below to a thin pointer. The reason
7732 for this is that we need to have a fat pointer someplace in order
7733 to properly compute the size. */
7737 gnu_ptr));
7739 /* If this is a fat pointer, the object must have been allocated with
7740 the template in front of the array. So pass the template address,
7741 and get the total size; do it by converting to a thin pointer. */
7743 gnu_ptr
7745 (TYPE_OBJECT_RECORD_TYPE
7747 gnu_ptr);
7751 /* If this is a thin pointer, the object must have been allocated with
7752 the template in front of the array. So pass the template address,
7753 and get the total size. */
7755 gnu_ptr
7757 gnu_ptr,
7759 byte_position
7760 (DECL_CHAIN
7763 /* If we have a special dynamic constrained subtype on the node, use
7764 it to compute the size; otherwise, use the designated subtype. */
7766 {
7767 gnu_actual_obj_type
7771 gnu_actual_obj_type
7773 gnu_actual_obj_type,
7776 }
7777 else
7783 gnu_result
7787 gnat_node);
7788 }
7796 else
7801 /* The only validation we currently do on an unchecked conversion is
7802 that of aliasing assumptions. */
7812 /* These nodes should only be present when annotating types. */
7818 /* Other nodes are not supposed to reach here. */
7820 }
7822 /* If we pushed the processing of the elaboration routine, pop it back. */
7826 /* When not optimizing, turn boolean rvalues B into B != false tests
7827 so that we can put the location information of the reference to B on
7828 the inequality operator for better debug info. */
7839 {
7840 gnu_result
7846 }
7848 /* Set the location information on the result if it's not a simple name.
7849 Note that we may have no result if we tried to build a CALL_EXPR node
7850 to a procedure with no side-effects and optimization is enabled. */
7854 /* If we're supposed to return something of void_type, it means we have
7855 something we're elaborating for effect, so just return. */
7859 /* If the result is a constant that overflowed, raise Constraint_Error. */
7861 {
7863 gnu_result
7866 N_Raise_Constraint_Error));
7867 }
7869 /* If the result has side-effects and is of an unconstrained type, protect
7870 the expression in case it will be referenced multiple times, i.e. for
7871 its value and to compute the size of an object. But do it neither for
7872 an object nor a renaming declaration, nor a return statement of a call
7873 to a function that returns an unconstrained record type with default
7874 discriminant, because there is no size to be computed in these cases
7875 and this will create a useless temporary. We must do this before any
7876 conversions. */
7887 /* Now convert the result to the result type, unless we are in one of the
7888 following cases:
7890 1. If this is the LHS of an assignment or an actual parameter of a
7891 call, return the result almost unmodified since the RHS will have
7892 to be converted to our type in that case, unless the result type
7893 has a simpler size. Likewise if there is just a no-op unchecked
7894 conversion in-between. Similarly, don't convert integral types
7895 that are the operands of an unchecked conversion since we need
7896 to ignore those conversions (for 'Valid).
7898 2. If we have a label (which doesn't have any well-defined type), a
7899 field or an error, return the result almost unmodified. Similarly,
7900 if the two types are record types with the same name, don't convert.
7901 This will be the case when we are converting from a packable version
7902 of a type to its original type and we need those conversions to be
7903 NOPs in order for assignments into these types to work properly.
7905 3. If the type is void or if we have no result, return error_mark_node
7906 to show we have no result.
7908 4. If this is a call to a function that returns with variable size and
7909 the call is used as the expression in either an object or a renaming
7910 declaration, return the result unmodified because we want to use the
7911 return slot optimization in this case.
7913 5. Finally, if the type of the result is already correct. */
7931 && (CONTAINS_PLACEHOLDER_P
7935 {
7936 /* Remove padding only if the inner object is of self-referential
7937 size: in that case it must be an object of unconstrained type
7938 with a default discriminant and we want to avoid copying too
7939 much data. */
7942 gnu_result);
7943 }
7952 {
7953 /* Remove any padding. */
7956 gnu_result);
7957 }
7967 ;
7972 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7979 }
7981 /* Similar to gnat_to_gnu, but discard any object that might be created in
7982 the course of the translation of GNAT_NODE, which must be an "external"
7983 expression in the sense that it will be elaborated elsewhere. */
7985 tree
7987 {
7991 /* Force the local context and create a fake scope that we zap
7992 at the end so declarations will not be stuck either in the
7993 global varpool or in the current scope. */
7995 {
7998 }
8009 /* Do not import locations from external units. */
8014 }
8015 \f
8016 /* Subroutine of above to push the exception label stack. GNU_STACK is
8017 a pointer to the stack to update and GNAT_LABEL, if present, is the
8018 label to push onto the stack. */
8020 static void
8022 {
8028 }
8029 \f
8030 /* Return true if the statement list STMT_LIST is empty. */
8032 static bool
8034 {
8035 tree_stmt_iterator tsi;
8038 {
8041 /* Anything else than an empty STMT_STMT counts as something. */
8044 }
8047 }
8049 /* Record the current code position in GNAT_NODE. */
8051 static void
8053 {
8058 }
8060 /* Insert the code for GNAT_NODE at the position saved for that node. */
8062 static void
8064 {
8067 /* It's too late to remove the STMT_STMT itself at this point. */
8072 }
8073 \f
8074 /* Start a new statement group chained to the previous group. */
8076 void
8078 {
8081 /* First see if we can get one from the free list. */
8084 else
8090 }
8092 /* Add GNU_STMT to the current statement group. If it is an expression with
8093 no effects, it is ignored. */
8095 void
8097 {
8099 }
8101 /* Similar, but the statement is always added, regardless of side-effects. */
8103 void
8105 {
8107 }
8109 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
8111 void
8113 {
8114 /* Do not emit a location for renamings that come from generic instantiation,
8115 they are likely to disturb debugging. */
8120 }
8122 /* Similar, but the statement is always added, regardless of side-effects. */
8124 void
8126 {
8130 }
8132 /* Add a declaration statement for GNU_DECL to the current statement group.
8133 Get SLOC from Entity_Id. */
8135 void
8137 {
8141 /* If this is a variable that Gigi is to ignore, we may have been given
8142 an ERROR_MARK. So test for it. We also might have been given a
8143 reference for a renaming. So only do something for a decl. Also
8144 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
8152 /* If we are external or global, we don't want to output the DECL_EXPR for
8153 this DECL node since we already have evaluated the expressions in the
8154 sizes and positions as globals and doing it again would be wrong. */
8156 {
8157 /* Mark everything as used to prevent node sharing with subprograms.
8158 Note that walk_tree knows how to deal with TYPE_DECL, but neither
8159 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
8163 {
8167 }
8168 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
8173 }
8174 else
8177 /* If this is a variable and an initializer is attached to it, it must be
8178 valid for the context. Similar to init_const in create_var_decl. */
8185 {
8188 {
8191 }
8193 /* If GNU_DECL has a padded type, convert it to the unpadded
8194 type so the assignment is done properly. */
8200 }
8201 }
8203 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
8205 static tree
8207 {
8213 /* Don't mark a dummy type as visited because we want to mark its sizes
8214 and fields once it's filled in. */
8222 }
8224 /* Mark nodes rooted at T with TREE_VISITED and types as having their
8225 sized gimplified. We use this to indicate all variable sizes and
8226 positions in global types may not be shared by any subprogram. */
8228 void
8230 {
8232 }
8234 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
8235 set its location to that of GNAT_NODE if present, but with column info
8236 cleared so that conditional branches generated as part of the cleanup
8237 code do not interfere with coverage analysis tools. */
8239 static void
8241 {
8245 }
8247 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
8249 void
8251 {
8254 }
8256 /* Return code corresponding to the current code group. It is normally
8257 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
8258 BLOCK or cleanups were set. */
8260 tree
8262 {
8266 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
8267 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
8268 make a BIND_EXPR. Note that we nest in that because the cleanup may
8269 reference variables in the block. */
8281 /* Remove this group from the stack and add it to the free list. */
8287 }
8289 /* Return whether the current statement group may fall through. */
8293 {
8296 else
8298 }
8300 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
8301 statements.*/
8303 static void
8305 {
8306 Node_Id gnat_node;
8312 }
8314 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
8315 If BINDING_P is true, push and pop a binding level around the list. */
8317 static tree
8319 {
8331 }
8332 \f
8333 /* Generate GIMPLE in place for the expression at *EXPR_P. */
8335 int
8338 {
8341 tree op;
8347 {
8349 /* If this is an aggregate type, build a null pointer of the appropriate
8350 type and dereference it. */
8355 integer_zero_node));
8356 /* Otherwise, just make a VAR_DECL. */
8357 else
8358 {
8361 }
8367 /* We should only do this if we are just elaborating for side-effects,
8368 but we can't know that yet. */
8375 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
8376 is put into static memory. We know that it's going to be read-only
8377 given the semantics we have and it must be in static memory when the
8378 reference is in an elaboration procedure. */
8380 {
8384 }
8386 /* Replace atomic loads with their first argument. That's necessary
8387 because the gimplifier would create a temporary otherwise. */
8390 {
8393 {
8399 else
8401 }
8402 else
8404 }
8411 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
8412 type to a scalar one, explicitly create the local temporary. That's
8413 required if the type is passed by reference. */
8417 {
8426 }
8433 /* The expressions for the RM bounds must be gimplified to ensure that
8434 they are properly elaborated. See gimplify_decl_expr. */
8438 {
8443 {
8448 {
8452 }
8456 {
8460 }
8462 }
8467 }
8469 /* ... fall through ... */
8473 }
8474 }
8476 /* Generate GIMPLE in place for the statement at *STMT_P. */
8478 static enum gimplify_status
8480 {
8484 {
8490 {
8496 /* Build the condition expression from the test, if any. */
8498 {
8499 /* Deal with the optimization hints. */
8503 annot_expr_ivdep_kind));
8507 annot_expr_no_vector_kind));
8511 annot_expr_vector_kind));
8513 gnu_cond
8516 }
8518 /* Set to emit the statements of the loop. */
8521 /* We first emit the start label and then a conditional jump to the
8522 end label if there's a top condition, then the update if it's at
8523 the top, then the body of the loop, then a conditional jump to
8524 the end label if there's a bottom condition, then the update if
8525 it's at the bottom, and finally a jump to the start label and the
8526 definition of the end label. */
8528 gnu_start_label),
8529 stmt_p);
8550 gnu_end_label),
8551 stmt_p);
8553 }
8556 /* Build a statement to jump to the corresponding end label, then
8557 see if it needs to be conditional. */
8566 }
8567 }
8568 \f
8569 /* Force a reference to each of the entities in GNAT_PACKAGE recursively.
8571 This routine is exclusively called in type_annotate mode, to compute DDA
8572 information for types in withed units, for ASIS use. */
8574 static void
8576 {
8577 Entity_Id gnat_entity;
8582 {
8585 /* We are interested only in entities visible from the main unit. */
8589 /* Skip stuff internal to the compiler. */
8599 /* Skip named numbers. */
8603 /* Skip generic declarations. */
8607 /* Skip formal objects. */
8611 /* Skip package bodies. */
8615 /* Skip limited views that point back to the main unit. */
8621 /* Skip types that aren't frozen. */
8625 /* Recurse on real packages that aren't in the main unit. */
8627 {
8631 }
8632 else
8634 }
8635 }
8637 /* Force a reference to each of the entities in packages withed by GNAT_NODE.
8638 Operate recursively but check that we aren't elaborating something more
8639 than once.
8641 This routine is exclusively called in type_annotate mode, to compute DDA
8642 information for types in withed units, for ASIS use. */
8644 static void
8646 {
8647 Entity_Id gnat_with_clause;
8649 /* Process each unit only once. As we trace the context of all relevant
8650 units transitively, including generic bodies, we may encounter the
8651 same generic unit repeatedly. */
8655 /* Save entities in all context units. A body may have an implicit_with
8656 on its own spec, if the context includes a child unit, so don't save
8657 the spec twice. */
8664 {
8674 {
8677 /* Retrieve compilation unit node of generic body. */
8682 /* If body is available, elaborate its context. */
8685 }
8686 }
8690 }
8691 \f
8692 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8694 static void
8696 {
8701 /* If this is a package, we need to generate code for the package. */
8703 {
8704 insert_code_for
8708 }
8710 /* Don't do anything for class-wide types as they are always transformed
8711 into their root type. */
8715 /* Check for an old definition if this isn't an object with address clause,
8716 since the saved GCC tree is the address expression in that case. */
8717 gnu_old
8721 /* Don't do anything for subprograms that may have been elaborated before
8722 their freeze nodes. This can happen, for example, because of an inner
8723 call in an instance body or because of previous compilation of a spec
8724 for inlining purposes. */
8732 /* If we have a non-dummy type old tree, we have nothing to do, except for
8733 aborting, since this node was never delayed as it should have been. We
8734 let this happen for concurrent types and their Corresponding_Record_Type,
8735 however, because each might legitimately be elaborated before its own
8736 freeze node, e.g. while processing the other. */
8740 {
8745 }
8747 /* Reset the saved tree, if any, and elaborate the object or type for real.
8748 If there is a full view, elaborate it and use the result. And, if this
8749 is the root type of a class-wide type, reuse it for the latter. */
8751 {
8756 {
8763 {
8766 }
8767 }
8773 }
8777 {
8786 /* Propagate back-annotations from full view to partial view. */
8796 /* The above call may have defined this entity (the simplest example
8797 of this is when we have a private enumeral type since the bounds
8798 will have the public view). */
8801 }
8802 else
8803 {
8804 tree gnu_init
8810 }
8817 /* If we have an old type and we've made pointers to this type, update those
8818 pointers. If this is a Taft amendment type in the main unit, we need to
8819 mark the type as used since other units referencing it don't see the full
8820 declaration and, therefore, cannot mark it as used themselves. */
8822 {
8829 }
8830 }
8831 \f
8832 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8833 We make two passes, one to elaborate anything other than bodies (but
8834 we declare a function if there was no spec). The second pass
8835 elaborates the bodies.
8837 GNAT_END_LIST gives the element in the list past the end. Normally,
8838 this is Empty, but can be First_Real_Statement for a
8839 Handled_Sequence_Of_Statements.
8841 We make a complete pass through both lists if PASS1P is true, then make
8842 the second pass over both lists if PASS2P is true. The lists usually
8843 correspond to the public and private parts of a package. */
8845 static void
8848 {
8850 Node_Id gnat_decl;
8860 {
8861 /* For package specs, we recurse inside the declarations,
8862 thus taking the two pass approach inside the boundary. */
8870 /* Similarly for any declarations in the actions of a
8871 freeze node. */
8873 {
8876 }
8878 /* Package bodies with freeze nodes get their elaboration deferred
8879 until the freeze node, but the code must be placed in the right
8880 place, so record the code position now. */
8888 (Corresponding_Spec
8891 record_code_position
8894 /* We defer most subprogram bodies to the second pass. */
8896 {
8898 {
8904 }
8905 }
8907 /* For bodies and stubs that act as their own specs, the entity
8908 itself must be elaborated in the first pass, because it may
8909 be used in other declarations. */
8911 {
8912 Node_Id gnat_subprog_id
8919 }
8921 /* Concurrent stubs stand for the corresponding subprogram bodies,
8922 which are deferred like other bodies. */
8925 ;
8927 /* Renamed subprograms may not be elaborated yet at this point
8928 since renamings do not trigger freezing. Wait for the second
8929 pass to take care of them. */
8931 ;
8933 else
8935 }
8937 /* Here we elaborate everything we deferred above except for package bodies,
8938 which are elaborated at their freeze nodes. Note that we must also
8939 go inside things (package specs and freeze nodes) the first pass did. */
8945 {
8964 }
8965 }
8966 \f
8967 /* Make a unary operation of kind CODE using build_unary_op, but guard
8968 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8969 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8970 the operation is to be performed in that type. GNAT_NODE is the gnat
8971 node conveying the source location for which the error should be
8972 signaled. */
8974 static tree
8976 Node_Id gnat_node)
8977 {
8986 }
8988 /* Make a binary operation of kind CODE using build_binary_op, but guard
8989 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8990 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8991 Usually the operation is to be performed in that type. GNAT_NODE is
8992 the GNAT node conveying the source location for which the error should
8993 be signaled. */
8995 static tree
8998 {
9007 /* Assert that the precision is a power of 2. */
9010 /* Prefer a constant on the RHS to simplify checks. */
9014 {
9018 }
9022 /* If we can fold the expression to a constant, just return it.
9023 The caller will deal with overflow, no need to generate a check. */
9027 /* If no operand is a constant, we use the generic implementation. */
9029 {
9030 /* Never inline a 64-bit mult for a 32-bit target, it's way too long. */
9032 {
9037 }
9042 {
9054 }
9057 tree call
9065 return
9067 }
9069 /* If one operand is a constant, we expose the overflow condition to enable
9070 a subsequent simplication or even elimination. */
9072 {
9076 /* When rhs > 0, overflow when lhs > type_max - rhs. */
9081 /* When rhs < 0, overflow when lhs < type_min - rhs. */
9085 else
9091 {
9094 /* When lhs > 0, overflow when rhs < lhs - type_max. */
9099 /* When lhs < 0, overflow when rhs > lhs - type_min. */
9103 else
9105 }
9106 else
9107 {
9110 /* When rhs > 0, overflow when lhs < type_min + rhs. */
9115 /* When rhs < 0, overflow when lhs > type_max + rhs. */
9119 else
9121 }
9127 {
9134 /* When rhs > 1, overflow outside [type_min/rhs; type_max/rhs]. */
9135 check
9141 }
9143 {
9148 /* When rhs == -1, overflow if lhs == type_min. */
9149 check
9151 else
9152 /* When rhs < -1, overflow outside [type_max/rhs; type_min/rhs]. */
9153 check
9159 }
9160 else
9166 }
9169 }
9171 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
9172 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
9173 which we have to check. GNAT_NODE is the GNAT node conveying the source
9174 location for which the error should be signaled. */
9176 static tree
9178 {
9182 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
9183 This can for example happen when translating 'Val or 'Value. */
9187 /* Range checks can only be applied to types with ranges. */
9191 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
9192 we can't do anything since we might be truncating the bounds. No
9193 check is needed in this case. */
9199 /* Checked expressions must be evaluated only once. */
9202 /* Note that the form of the check is
9203 (not (expr >= lo)) or (not (expr <= hi))
9204 the reason for this slightly convoluted form is that NaNs
9205 are not considered to be in range in the float case. */
9206 return emit_check
9208 invert_truthvalue
9212 TYPE_MIN_VALUE
9214 invert_truthvalue
9218 TYPE_MAX_VALUE
9221 }
9222 \f
9223 /* GNU_COND contains the condition corresponding to an index, overflow or
9224 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR
9225 if GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
9226 REASON is the code that says why the exception is raised. GNAT_NODE is
9227 the node conveying the source location for which the error should be
9228 signaled.
9230 We used to propagate TREE_SIDE_EFFECTS from GNU_EXPR to the COND_EXPR,
9231 overwriting the setting inherited from the call statement, on the ground
9232 that the expression need not be evaluated just for the check. However
9233 that's incorrect because, in the GCC type system, its value is presumed
9234 to be valid so its comparison against the type bounds always yields true
9235 and, therefore, could be done without evaluating it; given that it can
9236 be a computation that overflows the bounds, the language may require the
9237 check to fail and thus the expression to be evaluated in this case. */
9239 static tree
9241 {
9242 tree gnu_call
9244 return
9250 gnu_expr);
9251 }
9252 \f
9253 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
9254 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
9255 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
9256 float to integer conversion with truncation; otherwise round.
9257 GNAT_NODE is the GNAT node conveying the source location for which the
9258 error should be signaled. */
9260 static tree
9263 {
9270 /* If we are not doing any checks, the output is an integral type and the
9271 input is not a floating-point type, just do the conversion. This is
9272 required for packed array types and is simpler in all cases anyway. */
9274 && !overflowp
9279 /* First convert the expression to its base type. This
9280 will never generate code, but makes the tests below much simpler.
9281 But don't do this if converting from an integer type to an unconstrained
9282 array type since then we need to get the bounds from the original
9283 (unpacked) type. */
9287 /* If overflow checks are requested, we need to be sure the result will
9288 fit in the output base type. But don't do this if the input
9289 is integer and the output floating-point. */
9292 {
9293 /* Ensure GNU_EXPR only gets evaluated once. */
9301 /* Convert the lower bounds to signed types, so we're sure we're
9302 comparing them properly. Likewise, convert the upper bounds
9303 to unsigned types. */
9305 gnu_in_lb
9310 gnu_in_ub
9314 gnu_out_lb
9318 gnu_out_ub
9321 /* Check each bound separately and only if the result bound
9322 is tighter than the bound on the input type. Note that all the
9323 types are base types, so the bounds must be constant. Also,
9324 the comparison is done in the base type of the input, which
9325 always has the proper signedness. First check for input
9326 integer (which means output integer), output float (which means
9327 both float), or mixed, in which case we always compare.
9328 Note that we have to do the comparison which would *fail* in the
9329 case of an error since if it's an FP comparison and one of the
9330 values is a NaN or Inf, the comparison will fail. */
9337 gnu_cond
9338 = invert_truthvalue
9341 gnu_out_lb)));
9349 gnu_cond
9351 invert_truthvalue
9353 gnu_input,
9355 gnu_out_ub))));
9360 }
9362 /* Now convert to the result base type. If this is a non-truncating
9363 float-to-integer conversion, round. */
9367 {
9373 /* The following calculations depend on proper rounding to even
9374 of each arithmetic operation. In order to prevent excess
9375 precision from spoiling this property, use the widest hardware
9376 floating-point type if FP_ARITH_MAY_WIDEN is true. */
9377 calc_type
9380 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
9387 /* If the input is strictly negative, subtract this value
9388 and otherwise add it from the input. For 0.5, the result
9389 is exactly between 1.0 and the machine number preceding 1.0
9390 (for calc_type). Since the last bit of 1.0 is even, this 0.5
9391 will round to 1.0, while all other number with an absolute
9392 value less than 0.5 round to 0.0. For larger numbers exactly
9393 halfway between integers, rounding will always be correct as
9394 the true mathematical result will be closer to the higher
9395 integer compared to the lower one. So, this constant works
9396 for all floating-point numbers.
9398 The reason to use the same constant with subtract/add instead
9399 of a positive and negative constant is to allow the comparison
9400 to be scheduled in parallel with retrieval of the constant and
9401 conversion of the input to the calc_type (if necessary). */
9406 gnu_comp
9408 gnu_add_pred_half
9410 gnu_subtract_pred_half
9414 }
9420 else
9423 /* Finally, do the range check if requested. Note that if the result type
9424 is a modular type, the range check is actually an overflow check. */
9431 }
9432 \f
9433 /* Return true if GNU_EXPR can be directly addressed. This is the case
9434 unless it is an expression involving computation or if it involves a
9435 reference to a bitfield or to an object not sufficiently aligned for
9436 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
9437 be directly addressed as an object of this type.
9439 *** Notes on addressability issues in the Ada compiler ***
9441 This predicate is necessary in order to bridge the gap between Gigi
9442 and the middle-end about addressability of GENERIC trees. A tree
9443 is said to be addressable if it can be directly addressed, i.e. if
9444 its address can be taken, is a multiple of the type's alignment on
9445 strict-alignment architectures and returns the first storage unit
9446 assigned to the object represented by the tree.
9448 In the C family of languages, everything is in practice addressable
9449 at the language level, except for bit-fields. This means that these
9450 compilers will take the address of any tree that doesn't represent
9451 a bit-field reference and expect the result to be the first storage
9452 unit assigned to the object. Even in cases where this will result
9453 in unaligned accesses at run time, nothing is supposed to be done
9454 and the program is considered as erroneous instead (see PR c/18287).
9456 The implicit assumptions made in the middle-end are in keeping with
9457 the C viewpoint described above:
9458 - the address of a bit-field reference is supposed to be never
9459 taken; the compiler (generally) will stop on such a construct,
9460 - any other tree is addressable if it is formally addressable,
9461 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
9463 In Ada, the viewpoint is the opposite one: nothing is addressable
9464 at the language level unless explicitly declared so. This means
9465 that the compiler will both make sure that the trees representing
9466 references to addressable ("aliased" in Ada parlance) objects are
9467 addressable and make no real attempts at ensuring that the trees
9468 representing references to non-addressable objects are addressable.
9470 In the first case, Ada is effectively equivalent to C and handing
9471 down the direct result of applying ADDR_EXPR to these trees to the
9472 middle-end works flawlessly. In the second case, Ada cannot afford
9473 to consider the program as erroneous if the address of trees that
9474 are not addressable is requested for technical reasons, unlike C;
9475 as a consequence, the Ada compiler must arrange for either making
9476 sure that this address is not requested in the middle-end or for
9477 compensating by inserting temporaries if it is requested in Gigi.
9479 The first goal can be achieved because the middle-end should not
9480 request the address of non-addressable trees on its own; the only
9481 exception is for the invocation of low-level block operations like
9482 memcpy, for which the addressability requirements are lower since
9483 the type's alignment can be disregarded. In practice, this means
9484 that Gigi must make sure that such operations cannot be applied to
9485 non-BLKmode bit-fields.
9487 The second goal is achieved by means of the addressable_p predicate,
9488 which computes whether a temporary must be inserted by Gigi when the
9489 address of a tree is requested; if so, the address of the temporary
9490 will be used in lieu of that of the original tree and some glue code
9491 generated to connect everything together. */
9493 static bool
9495 {
9496 /* For an integral type, the size of the actual type of the object may not
9497 be greater than that of the expected type, otherwise an indirect access
9498 in the latter type wouldn't correctly set all the bits of the object. */
9504 /* The size of the actual type of the object may not be smaller than that
9505 of the expected type, otherwise an indirect access in the latter type
9506 would be larger than the object. But only record types need to be
9507 considered in practice for this case. */
9514 {
9519 /* All DECLs are addressable: if they are in a register, we can force
9520 them to memory. */
9525 /* Taking the address of a dereference yields the original pointer. */
9530 /* Taking the address yields a pointer to the constant pool. */
9534 /* Taking the address of a static constructor yields a pointer to the
9535 tree constant pool. */
9547 /* All rvalues are deemed addressable since taking their address will
9548 force a temporary to be created by the middle-end. */
9552 /* The address of a compound expression is that of its 2nd operand. */
9556 /* We accept &COND_EXPR as soon as both operands are addressable and
9557 expect the outcome to be the address of the selected operand. */
9563 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
9564 the field is sufficiently aligned, in case it is subject
9565 to a pragma Component_Alignment. But we don't need to
9566 check the alignment of the containing record, as it is
9567 guaranteed to be not smaller than that of its most
9568 aligned field that is not a bit-field. */
9569 && (!STRICT_ALIGNMENT
9572 /* The field of a padding record is always addressable. */
9586 {
9587 /* This is addressable if we can avoid a copy. */
9591 && (!STRICT_ALIGNMENT
9596 && (!STRICT_ALIGNMENT
9602 }
9606 }
9607 }
9608 \f
9609 /* Do the processing for the declaration of a GNAT_ENTITY, a type or subtype.
9610 If a Freeze node exists for the entity, delay the bulk of the processing.
9611 Otherwise make a GCC type for GNAT_ENTITY and set up the correspondence. */
9613 void
9615 {
9616 tree gnu_old
9619 /* If we are to delay elaboration of this type, just do any elaboration
9620 needed for expressions within the declaration and make a dummy node
9621 for it and its Full_View (if any), in case something points to it.
9622 Do not do this if it has already been done (the only way that can
9623 happen is if the private completion is also delayed). */
9625 {
9629 {
9634 {
9638 }
9639 }
9642 }
9644 /* If we saved away a dummy type for this node, it means that this made the
9645 type that corresponds to the full type of an incomplete type. Clear that
9646 type for now and then update the type in the pointers below. But, if the
9647 saved type is not dummy, it very likely means that we have a use before
9648 declaration for the type in the tree, what we really cannot handle. */
9650 {
9655 }
9657 /* Now fully elaborate the type. */
9661 /* If we have an old type and we've made pointers to this type, update those
9662 pointers. If this is a Taft amendment type in the main unit, we need to
9663 mark the type as used since other units referencing it don't see the full
9664 declaration and, therefore, cannot mark it as used themselves. */
9666 {
9671 }
9673 /* If this is a record type corresponding to a task or protected type
9674 that is a completion of an incomplete type, perform a similar update
9675 on the type. ??? Including protected types here is a guess. */
9679 {
9680 tree gnu_task_old
9690 }
9691 }
9692 \f
9693 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9694 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
9695 associations that are from RECORD_TYPE. If we see an internal record, make
9696 a recursive call to fill it in as well. */
9698 static tree
9700 {
9702 tree field;
9705 {
9708 /* _Parent is an internal field, but may have values in the aggregate,
9709 so check for values first. */
9711 {
9714 }
9717 {
9722 }
9723 else
9724 /* If we have a record subtype, the names will match, but not the
9725 actual FIELD_DECLs. */
9728 {
9731 }
9737 }
9740 }
9742 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9743 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9744 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9746 static tree
9748 {
9751 /* We test for GNU_FIELD being empty in the case where a variant
9752 was the last thing since we don't take things off GNAT_ASSOC in
9753 that case. We check GNAT_ASSOC in case we have a variant, but it
9754 has no fields. */
9757 {
9762 /* The expander is supposed to put a single component selector name
9763 in every record component association. */
9766 /* Ignore discriminants that have Corresponding_Discriminants in tagged
9767 types since we'll be setting those fields in the parent subtype. */
9773 /* Also ignore discriminants of Unchecked_Unions. */
9778 /* Before assigning a value in an aggregate make sure range checks
9779 are done if required. Then convert to the type of the field. */
9785 /* Add the field and expression to the list. */
9787 }
9792 {
9793 /* Verify that every entry in GNU_LIST was used. */
9796 }
9799 }
9801 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9802 the first element of an array aggregate. It may itself be an aggregate.
9803 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9804 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9805 for range checking. */
9807 static tree
9809 Entity_Id gnat_component_type)
9810 {
9815 {
9816 tree gnu_expr;
9818 /* If the expression is itself an array aggregate then first build the
9819 innermost constructor if it is part of our array (multi-dimensional
9820 case). */
9826 gnat_component_type);
9827 else
9828 {
9831 /* Before assigning the element to the array, make sure it is
9832 in range. */
9835 }
9842 integer_one_node));
9843 }
9846 }
9847 \f
9848 /* Process a N_Validate_Unchecked_Conversion node. */
9850 static void
9852 {
9856 /* If the target is a pointer type, see if we are either converting from a
9857 non-pointer or from a pointer to a type with a different alias set and
9858 warn if so, unless the pointer has been marked to alias everything. */
9861 {
9871 target_alias_set)))
9872 {
9876 gnat_node);
9879 }
9880 }
9882 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9883 mitigate the problem in this case, so we unconditionally warn. */
9885 {
9886 tree gnu_source_desig_type
9890 tree gnu_target_desig_type
9897 target_alias_set)))
9898 {
9902 gnat_node);
9903 }
9904 }
9905 }
9906 \f
9907 /* EXP is to be treated as an array or record. Handle the cases when it is
9908 an access object and perform the required dereferences. */
9910 static tree
9912 {
9913 /* If the type is a pointer, dereference it. */
9918 /* If we got a padded type, remove it too. */
9923 }
9924 \f
9925 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9926 location and false if it doesn't. If CLEAR_COLUMN is true, set the column
9927 information to 0. */
9929 bool
9931 {
9936 {
9939 }
9946 /* We can have zero if pragma Source_Reference is in effect. */
9950 /* Translate the location. */
9951 *locus
9955 }
9957 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9958 don't do anything if it doesn't correspond to a source location. And,
9959 if CLEAR_COLUMN is true, set the column information to 0. */
9961 static void
9963 {
9964 location_t locus;
9970 }
9972 /* More elaborate version of set_expr_location_from_node to be used in more
9973 general contexts, for example the result of the translation of a generic
9974 GNAT node. */
9976 static void
9978 {
9979 /* Set the location information on the node if it is a real expression.
9980 References can be reused for multiple GNAT nodes and they would get
9981 the location information of their last use. Also make sure not to
9982 overwrite an existing location as it is probably more precise. */
9985 {
9986 CASE_CONVERT:
9995 /* ... fall through ... */
9999 {
10002 }
10004 }
10005 }
10007 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
10008 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
10009 most sense. Return true if a sensible assignment was performed. */
10011 static bool
10013 {
10014 Node_Id gnat_end_label;
10015 location_t end_locus;
10017 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
10018 end_locus when there is one. We consider only GNAT nodes with a possible
10019 End_Label attached. If the End_Label actually was unassigned, fallback
10020 on the original node. We'd better assign an explicit sloc associated with
10021 the outer construct in any case. */
10024 {
10037 }
10042 /* Some expanded subprograms have neither an End_Label nor a Sloc
10043 attached. Notify that to callers. For a block statement with no
10044 End_Label, clear column information, so that the tree for a
10045 transient block does not receive the sloc of a source condition. */
10052 {
10063 }
10064 }
10065 \f
10066 /* Return a colon-separated list of encodings contained in encoded Ada
10067 name. */
10071 {
10075 }
10077 /* Extract the Ada name from an encoded name. */
10081 {
10085 }
10086 \f
10087 /* Post an error message. MSG is the error message, properly annotated.
10088 NODE is the node at which to post the error and the node to use for the
10089 '&' substitution. */
10091 void
10093 {
10094 String_Template temp;
10095 String_Pointer sp;
10105 }
10107 /* Similar to post_error, but NODE is the node at which to post the error and
10108 ENT is the node to use for the '&' substitution. */
10110 void
10112 {
10113 String_Template temp;
10114 String_Pointer sp;
10124 }
10126 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
10128 void
10130 {
10133 }
10135 /* Similar to post_error_ne, but T is a GCC tree representing the number to
10136 write. If T represents a constant, the text inside curly brackets in
10137 MSG will be output (presumably including a '^'). Otherwise it will not
10138 be output and the text inside square brackets will be output instead. */
10140 void
10142 {
10149 {
10152 }
10153 else
10157 {
10163 ;
10164 else
10166 }
10171 }
10173 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
10175 void
10178 {
10181 }
10183 /* Return a label to branch to for the exception type in KIND or NULL_TREE
10184 if none. */
10186 tree
10188 {
10190 {
10202 }
10205 }
10207 /* Return the decl for the current elaboration procedure. */
10209 static tree
10211 {
10213 }
10215 /* Initialize the table that maps GNAT codes to GCC codes for simple
10216 binary and unary operations. */
10218 static void
10220 {
10245 }