| blob | 92c8dc33af821333dd4c8db0365bd0b4c661ee0d |
1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2023, 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 ****************************************************************************/
72 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
73 for fear of running out of stack space. If we need more, we use xmalloc
74 instead. */
75 #define ALLOCA_THRESHOLD 1000
77 /* Pointers to front-end tables accessed through macros. */
88 /* Highest number in the front-end node table. */
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 /* List of expressions of pragma Compile_Time_{Error|Warning} in the unit. */
102 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
103 of unconstrained array IN parameters to avoid emitting a great deal of
104 redundant instructions to recompute them each time. */
108 tree first;
109 tree last;
110 tree length;
111 };
115 /* Structure used to record information for a function. */
118 bitmap named_ret_val;
121 };
123 #define f_parm_attr_cache \
124 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
126 #define f_named_ret_val \
127 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
129 #define f_other_ret_val \
130 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
132 #define f_gnat_ret \
133 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
135 /* A structure used to gather together information about a statement group.
136 We use this to gather related statements, for example the "then" part
137 of a IF. In the case where it represents a lexical scope, we may also
138 have a BLOCK node corresponding to it and/or cleanups. */
145 };
149 /* List of unused struct stmt_group nodes. */
152 /* A structure used to record information on elaboration procedures
153 we've made and need to process.
155 ??? gnat_node should be Node_Id, but gengtype gets confused. */
161 };
165 /* Stack of exception pointer variables. Each entry is the VAR_DECL
166 that stores the address of the raised exception. Nonzero means we
167 are in an exception handler. Not used in the zero-cost case. */
170 /* In ZCX case, current exception pointer. Used to re-raise it. */
173 /* Stack for storing the current elaboration procedure decl. */
176 /* Stack of labels to be used as a goto target instead of a return in
177 some functions. See processing for N_Subprogram_Body. */
180 /* Stack of variable for the return value of a function with copy-in/copy-out
181 parameters. See processing for N_Subprogram_Body. */
184 /* Structure used to record information for a range check. */
186 tree low_bound;
187 tree high_bound;
188 tree disp;
190 tree type;
191 tree invariant_cond;
192 tree inserted_cond;
193 };
197 /* Structure used to record information for a loop. */
199 tree fndecl;
200 tree stmt;
201 tree loop_var;
202 tree low_bound;
203 tree high_bound;
204 tree omp_loop_clauses;
205 tree omp_construct_clauses;
209 };
213 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
216 /* The stacks for N_{Push,Pop}_*_Label. */
221 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
254 /* This makes gigi's file_info_ptr visible in this translation unit,
255 so that Sloc_to_locus can look it up when deciding whether to map
256 decls to instances. */
260 /* Return the string of the identifier allocated for the file name Id. */
264 {
265 /* __gnat_to_canonical_file_spec translates file names from pragmas
266 Source_Reference that contain host style syntax not understood by GDB. */
269 /* Use the identifier table to make a permanent copy of the file name as
270 the name table gets reallocated after Gigi returns but before all the
271 debugging information is output. */
273 }
275 /* This is the main program of the back-end. It sets up all the table
276 structures and then generates code. */
278 void
291 Nat number_file,
293 Entity_Id standard_address,
294 Entity_Id standard_boolean,
295 Entity_Id standard_character,
296 Entity_Id standard_exception_type,
297 Entity_Id standard_integer,
298 Entity_Id standard_long_long_float,
299 Int gigi_operating_mode)
300 {
301 Node_Id gnat_iter;
302 Entity_Id gnat_literal;
322 {
325 }
328 {
329 /* We rely on the order isomorphism between files and line maps. */
331 {
335 }
337 /* We create the line map for a source file at once, with a fixed number
338 of columns chosen to avoid jumping over the next power of 2. */
344 }
348 /* Declare the name of the compilation unit as the first global
349 name in order to make the middle-end fully deterministic. */
353 /* Initialize ourselves. */
358 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
359 errors. */
361 {
364 }
366 /* Enable GNAT stack checking method if needed */
368 {
372 gnat_root);
373 }
375 /* Retrieve alignment settings. */
379 /* Record the builtin types. */
386 /* Save the type we made for address as the type for Standard.Address. */
391 /* Likewise for integer as the type for Standard.Integer. */
396 /* Likewise for character as the type for Standard.Character. */
402 /* Likewise for boolean as the type for Standard.Boolean. */
421 /* Declare the building blocks of function nodes. */
425 /* Now declare run-time functions. */
426 malloc_decl
429 NULL_TREE),
434 free_decl
441 realloc_decl
445 NULL_TREE),
449 /* This is used for 64-bit multiplication with overflow checking. */
451 mulv64_decl
459 {
461 mulv128_decl
464 int128_type,
465 int128_type,
466 NULL_TREE),
469 }
471 /* Name of the _Parent field in tagged record types. */
474 /* Name of the Not_Handled_By_Others field in exception record types. */
477 /* Make the types and functions used for exception processing. */
480 set_exception_parameter_decl
481 = create_subprog_decl
484 NULL_TREE),
487 /* Hooks to call when entering/leaving an exception handler. */
490 begin_handler_decl
494 Empty);
495 /* __gnat_begin_handler_v1 is not a dummy procedure, but we arrange
496 for it not to throw. */
502 end_handler_decl
506 Empty);
509 unhandled_except_decl
513 Empty);
515 /* Indicate that it never returns. */
517 reraise_zcx_decl
521 Empty);
523 /* Dummy objects to materialize "others" and "all others" in the exception
524 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
525 the types to use. */
526 others_decl
533 all_others_decl
540 unhandled_others_decl
547 /* If in no exception handlers mode, all raise statements are redirected to
548 __gnat_last_chance_handler. */
550 {
551 /* Indicate that it never returns. */
556 tree decl
557 = create_subprog_decl
560 Empty);
563 }
564 else
565 {
566 /* Otherwise, make one decl for each exception reason. */
572 i == CE_Index_Check_Failed
576 }
578 /* Build the special descriptor type and its null node if needed. */
580 {
592 {
593 tree field
600 elt--;
601 }
606 }
608 longest_float_type_node
615 /* Initialize the GCC support for FP operations. */
618 /* Install the builtins we might need, either internally or as user-available
619 facilities for Intrinsic imports. Note that this must be done after the
620 GCC exception mechanism is initialized. */
629 /* Process any Pragma Ident for the main unit. */
634 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
638 /* Save the current optimization options again after the above possible
639 global_options changes. */
640 optimization_default_node
644 /* Now translate the compilation unit proper. */
647 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
648 the very end to avoid having to second-guess the front-end when we run
649 into dummy nodes during the regular processing. */
654 /* Finally see if we have any elaboration procedures to deal with. */
656 {
659 /* We should have a BIND_EXPR but it may not have any statements in it.
660 If it doesn't have any, we have nothing to do except for setting the
661 flag on the GNAT node. Otherwise, process the function as others. */
667 else
668 {
672 }
673 }
675 /* Destroy ourselves. */
680 /* We cannot track the location of errors past this point. */
682 }
684 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
685 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
687 static tree
689 {
698 {
700 ftype
704 }
705 else
706 {
711 ftype
716 }
718 /* Indicate that it never returns. */
720 result
726 }
728 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
729 an N_Attribute_Reference. */
731 static int
733 {
735 {
773 }
774 }
776 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
777 is the type that will be used for GNAT_NODE in the translated GNU tree.
778 CONSTANT indicates whether the underlying object represented by GNAT_NODE
779 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
780 whether its value is the address of another constant. If it isn't, then
781 ADDRESS_OF_CONSTANT is ignored.
783 The function climbs up the GNAT tree starting from the node and returns 1
784 upon encountering a node that effectively requires an lvalue downstream.
785 It returns int instead of bool to facilitate usage in non-purely binary
786 logic contexts. */
788 static int
791 {
795 {
805 /* If the parameter is by reference, an lvalue is required. */
812 address_of_constant);
816 {
817 const unsigned char id
820 }
821 else
825 /* Only the array expression can require an lvalue. */
829 /* ??? Consider that referencing an indexed component with a variable
830 index forces the whole aggregate to memory. Note that testing only
831 for literals is conservative, any static expression in the RM sense
832 could probably be accepted with some additional work. */
842 /* ... fall through ... */
846 /* Only the prefix expression can require an lvalue. */
855 /* We need to preserve addresses through a renaming. */
859 /* We cannot use a constructor if this is an atomic object because
860 the actual assignment might end up being done component-wise. */
864 /* We don't use a constructor if this is a class-wide object
865 because the effective type of the object is the equivalent
866 type of the class-wide subtype and it smashes most of the
867 data into an array of bytes to which we cannot convert. */
872 /* We cannot use a constructor if the LHS is an atomic object because
873 the actual assignment might end up being done component-wise. */
884 /* ... fall through ... */
888 /* We must look through all conversions because we may need to bypass
889 an intermediate conversion that is meant to be purely formal. */
895 /* We look through dereferences for address of constant because we need
896 to handle the special cases listed above. */
902 /* ... fall through ... */
906 }
909 }
911 /* Return true if an lvalue should be used for GNAT_NODE. GNU_TYPE is the type
912 that will be used for GNAT_NODE in the translated GNU tree and is assumed to
913 be an aggregate type.
915 The function climbs up the GNAT tree starting from the node and returns true
916 upon encountering a node that makes it doable to decide. lvalue_required_p
917 should have been previously invoked on the arguments and returned false. */
919 static bool
921 {
925 {
929 /* Even if the parameter is by copy, prefer an lvalue. */
933 /* Likewise for a return value. */
938 /* If an elementary component is used, take it from the constant. */
942 /* ... fall through ... */
949 /* For an aggregate object declaration, return false consistently. */
953 /* For an aggregate assignment, decide based on the size. */
954 {
957 }
966 /* We should only reach here through the N_Qualified_Expression case.
967 Force an lvalue for aggregate types since a block-copy to the newly
968 allocated area of memory is made. */
973 }
976 }
979 /* Return true if T is a constant DECL node that can be safely replaced
980 by its initializer. */
982 static bool
984 {
988 /* Return false for aggregate types that contain a placeholder since
989 their initializers cannot be manipulated easily. */
996 }
998 /* Return an expression equivalent to EXP but where constant DECL nodes
999 have been replaced by their initializer. */
1001 static tree
1003 {
1005 tree op0;
1008 {
1034 /* If the index is not itself constant, then nothing can be folded. */
1055 }
1058 }
1060 /* Return true if TYPE and DEF_TYPE are compatible GNAT types for Gigi. */
1062 static bool
1064 {
1065 /* The trivial case. */
1069 /* A class-wide type is equivalent to a subtype of itself. */
1073 /* A packed array type is compatible with its implementation type. */
1077 /* If both types are Itypes, one may be a copy of the other. */
1081 /* If the type is incomplete and comes from a limited context, then also
1082 consider its non-limited view. */
1088 /* If the type is incomplete/private, then also consider its full view. */
1094 }
1096 /* Return the full view of a private constant E, or of a renaming thereof, if
1097 its type has discriminants, and Empty otherwise. */
1099 static Entity_Id
1101 {
1116 }
1118 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Identifier, to a GCC
1119 tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where we should
1120 place the result type. */
1122 static tree
1124 {
1128 Entity_Id gnat_result_type;
1130 /* If GNAT_NODE is a constant, whether we should use the initialization
1131 value instead of the constant entity, typically for scalars with an
1132 address clause when the parent doesn't require an lvalue. */
1134 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1135 specific circumstances only, so evaluated lazily. < 0 means
1136 unknown, > 0 means known true, 0 means known false. */
1139 /* If the Etype of this node is not the same as that of the Entity, then
1140 something went wrong, probably in generic instantiation. However, this
1141 does not apply to types. Since we sometime have strange Ekind's, just
1142 do this test for objects, except for discriminants because their type
1143 may have been changed to a subtype by Exp_Ch3.Adjust_Discriminants. */
1150 /* If this is a reference to a deferred constant whose partial view is of
1151 unconstrained private type, the proper type is on the full view of the
1152 constant, not on the full view of the type which may be unconstrained. */
1155 {
1158 }
1159 else
1160 {
1161 /* We use the Actual_Subtype only if it has already been elaborated,
1162 as we may be invoked precisely during its elaboration, otherwise
1163 the Etype. Avoid using it for packed arrays to simplify things,
1164 except in a return statement because we need the actual size and
1165 the front-end does not make it explicit in this case. */
1175 else
1177 }
1179 /* Expand the type of this identifier first if it is needed, in case it is an
1180 enumeral literal, which only get made when the type is expanded. There is
1181 no order-of-elaboration issue here. */
1184 else
1187 /* If this is a non-imported elementary constant with an address clause,
1188 retrieve the value instead of a pointer to be dereferenced unless
1189 an lvalue is required. This is generally more efficient and actually
1190 required if this is a static expression because it might be used
1191 in a context where a dereference is inappropriate, such as a case
1192 statement alternative or a record discriminant. There is no possible
1193 volatile-ness short-circuit here since Volatile constants must be
1194 imported per C.6. */
1199 {
1200 require_lvalue
1203 }
1204 else
1205 {
1208 }
1210 /* Fetch the initialization value of a constant if requested. */
1212 {
1213 /* If this is a deferred constant, the initializer is attached to
1214 the full view. */
1219 }
1220 else
1223 /* Some objects (such as parameters passed by reference, globals of
1224 variable size, and renamed objects) actually represent the address
1225 of the object. In that case, we must do the dereference. Likewise,
1226 deal with parameters to foreign convention subprograms. */
1231 {
1234 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1237 gnu_result
1240 /* If it's a CONST_DECL, return the underlying constant like below. */
1247 /* Do the final dereference. */
1257 }
1259 /* If we have a constant declaration and its initializer, try to return the
1260 latter to avoid the need to call fold in lots of places and the need for
1261 elaboration code if this identifier is used as an initializer itself. */
1263 {
1269 /* If there is a (corresponding) variable or this is the address of a
1270 constant, we only want to return the initializer if an lvalue isn't
1271 required. Evaluate this now if we have not already done so. */
1273 require_lvalue
1275 address_of_constant)
1279 /* Finally retrieve the initializer if this is deemed valid. */
1282 }
1284 /* But for a constant renaming we couldn't do that incrementally for its
1285 definition because of the need to return an lvalue so, if the present
1286 context doesn't itself require an lvalue, we try again here. */
1290 {
1292 require_lvalue
1296 }
1298 /* The GNAT tree has the type of a function set to its result type, so we
1299 adjust here. Also use the type of the result if the Etype is a subtype
1300 that is nominally unconstrained. Likewise if this is a deferred constant
1301 of a discriminated type whose full view can be elaborated statically, to
1302 avoid problematic conversions to the nominal subtype. But remove any
1303 padding from the resulting type. */
1310 {
1314 }
1319 }
1321 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Pragma, to a GCC
1322 tree, which is returned. */
1324 static tree
1326 {
1328 Node_Id gnat_temp;
1330 /* Check for (and ignore) unrecognized pragmas. */
1334 const unsigned char id
1337 /* Save the expression of pragma Compile_Time_{Error|Warning} for later. */
1339 {
1343 }
1345 /* Stop there if we are just annotating types. */
1350 {
1352 /* Do nothing at top level: all such variables are already viewable. */
1359 {
1363 #ifdef ASM_COMMENT_START
1365 #endif
1372 #ifdef ASM_COMMENT_START
1377 NULL);
1380 #endif
1382 asm_constraint,
1383 NULL_TREE,
1384 tree_cons
1392 }
1399 {
1403 {
1426 }
1427 }
1433 {
1451 }
1461 {
1462 Node_Id gnat_expr;
1463 /* Preserve the location of the pragma. */
1467 diagnostic_t kind;
1472 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1474 {
1476 {
1489 }
1492 }
1494 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1496 {
1498 {
1509 }
1511 /* Deal with optional pattern (but ignore Reason => "..."). */
1514 {
1515 /* pragma Warnings (On | Off, Name) is handled differently. */
1520 }
1521 else
1522 {
1525 /* For pragma Warnings (Off), we save the current state... */
1529 /* ...so that, for pragma Warnings (On), we do not enable all
1530 the warnings but just restore the previous state. */
1531 else
1532 {
1535 }
1536 }
1539 }
1541 else
1544 /* This is the same implementation as in the C family of compilers. */
1548 {
1556 {
1559 }
1561 {
1564 }
1566 {
1569 }
1572 }
1573 else
1580 }
1585 }
1588 }
1590 /* Check the inline status of nested function FNDECL wrt its parent function.
1592 If a non-inline nested function is referenced from an inline external
1593 function, we cannot honor both requests at the same time without cloning
1594 the nested function in the current unit since it is private to its unit.
1595 We could inline it as well but it's probably better to err on the side
1596 of too little inlining.
1598 This must be done only on nested functions present in the source code
1599 and not on nested functions generated by the compiler, e.g. finalizers,
1600 because they may be not marked inline and we don't want them to block
1601 the inlining of the parent function. */
1603 static void
1605 {
1614 {
1619 {
1621 fndecl);
1623 }
1624 else
1625 {
1627 fndecl);
1629 }
1633 }
1634 }
1636 /* Return an expression for the length of TYPE, an integral type, computed in
1637 RESULT_TYPE, another integral type.
1639 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1640 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1641 which would only overflow in much rarer cases, for extremely large arrays
1642 we expect never to encounter in practice. Besides, the former computation
1643 required the use of potentially constraining signed arithmetics while the
1644 latter does not. Note that the comparison must be done in the original
1645 base index type in order to avoid any overflow during the conversion. */
1647 static tree
1649 {
1654 tree length
1660 length
1666 }
1668 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node, to a
1669 GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where we
1670 should place the result type. ATTRIBUTE is the attribute ID. */
1672 static tree
1674 {
1680 Entity_Id gnat_smo;
1682 /* If the input is a NULL_EXPR, make a new one. */
1684 {
1688 }
1690 /* If the input is a LOAD_EXPR of an unconstrained array type, the second
1691 operand contains the storage model object. */
1695 else
1699 {
1702 /* These just add or subtract the constant 1 since representation
1703 clauses for enumeration types are handled in the front-end. */
1709 gnu_result
1716 /* Conversions don't change the address of references but can cause
1717 build_unary_op to miss the references below, so strip them off.
1718 On the contrary, if the address-of operation causes a temporary
1719 to be created, then it must be created with the proper type. */
1725 /* If we are taking 'Address of an unconstrained object, this is the
1726 pointer to the underlying array. */
1730 /* If we are building a static dispatch table, we have to honor
1731 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1732 with the C++ ABI. We do it in the non-static case as well,
1733 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1736 {
1738 /* Descriptors can only be built here for top-level functions. */
1746 /* If we're not going to build the descriptor, we have to retrieve
1747 the one which will be built by the linker (or by the compiler
1748 later if a static chain is requested). */
1750 {
1753 gnu_result);
1755 }
1762 {
1764 {
1768 }
1769 else
1775 elt--;
1776 }
1780 }
1782 /* ... fall through ... */
1787 /* Taking the address of a type does not make sense. */
1791 gnu_result
1798 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1799 don't try to build a trampoline. */
1801 {
1807 /* On targets for which function symbols denote a descriptor, the
1808 code address is stored within the first slot of the descriptor
1809 so we do an additional dereference:
1810 result = *((result_type *) result)
1811 where we expect result to be of some pointer type already. */
1813 gnu_result
1816 gnu_result));
1817 }
1819 /* For 'Access, issue an error message if the prefix is a C++ method
1820 since it can use a special calling convention on some platforms,
1821 which cannot be propagated to the access type. */
1825 gnat_node);
1827 /* For other address attributes applied to a nested function,
1828 find an inner ADDR_EXPR and annotate it so that we can issue
1829 a useful warning with -Wtrampolines. */
1834 {
1837 /* Also check the inlining status. */
1840 /* Moreover, for 'Access or 'Unrestricted_Access with non-
1841 foreign-compatible representation, mark the ADDR_EXPR so
1842 that we can build a descriptor instead of a trampoline. */
1849 /* Otherwise, we need to check that we are not violating the
1850 No_Implicit_Dynamic_Code restriction. */
1853 }
1857 {
1859 tree gnu_obj_type;
1863 /* If this is fat pointer, the object must have been allocated with the
1864 template in front of the array. So compute the template address; do
1865 it by converting to a thin pointer. */
1867 gnu_ptr
1869 (TYPE_OBJECT_RECORD_TYPE
1871 gnu_ptr);
1875 /* If this is a thin pointer, the object must have been allocated with
1876 the template in front of the array. So compute the template address
1877 and return it. */
1879 gnu_ptr
1881 gnu_ptr,
1883 byte_position
1884 (DECL_CHAIN
1888 }
1895 /* Strip NOPs, conversions between original and packable versions, and
1896 unpadding from GNU_PREFIX. Note that we cannot simply strip every
1897 VIEW_CONVERT_EXPR because some of them may give the actual size, e.g.
1898 for nominally unconstrained packed array. We use GNU_EXPR to see
1899 if a COMPONENT_REF was involved. */
1905 == RECORD_TYPE
1916 /* Replace an unconstrained array type with the type of the underlying
1917 array, except for 'Max_Size_In_Storage_Elements because we need to
1918 return the (maximum) size requested for an allocator. */
1920 {
1924 }
1926 /* The type must be frozen at this point. */
1929 /* If we're looking for the size of a field, return the field size. */
1933 /* Otherwise, if the prefix is an object, or if we are looking for
1934 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1935 GCC size of the type. We make an exception for padded objects,
1936 as we do not take into account alignment promotions for the size.
1937 This is in keeping with the object case of gnat_to_gnu_entity. */
1944 {
1945 /* If this is a dereference and we have a special dynamic constrained
1946 subtype on the prefix, use it to compute the size; otherwise, use
1947 the designated subtype. */
1949 {
1950 Node_Id gnat_actual_subtype
1952 tree gnu_ptr_type
1957 {
1958 tree gnu_actual_obj_type
1960 gnu_type
1962 gnu_actual_obj_type,
1965 }
1966 }
1969 }
1971 /* Otherwise, the result is the RM size of the type. */
1972 else
1975 /* Deal with a self-referential size by qualifying the size with the
1976 object or returning the maximum size for a type. */
1978 {
1982 }
1986 /* If the type contains a template, subtract the padded size of the
1987 template, except for 'Max_Size_In_Storage_Elements because we need
1988 to return the (maximum) size requested for an allocator. */
1992 gnu_result
1996 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
2004 {
2017 else
2018 {
2023 /* If the default alignment of "double" or larger scalar types is
2024 specifically capped and there is an alignment clause neither
2025 on the type nor on the prefix itself, return the cap. */
2027 is_capped_double
2030 is_capped_double
2032 else
2042 else
2044 }
2047 }
2056 {
2063 else
2066 }
2068 /* ... fall through ... */
2071 {
2082 /* We treat unconstrained array In parameters specially. We also note
2083 whether we are dereferencing a pointer to unconstrained array. */
2086 {
2088 /* This is the direct case. */
2094 /* This is the indirect case. Note that we need to be sure that
2095 the access value cannot be null as we'll hoist the load. */
2098 {
2101 }
2102 else
2108 }
2110 /* If the prefix is the view conversion of a constrained array to an
2111 unconstrained form, we retrieve the constrained array because we
2112 might not be able to substitute the PLACEHOLDER_EXPR coming from
2113 the conversion. This can occur with the 'Old attribute applied
2114 to a parameter with an unconstrained type, which gets rewritten
2115 into a constrained local variable very late in the game. */
2118 && !CONTAINS_PLACEHOLDER_P
2121 else
2128 {
2130 tree gnu_type_temp;
2136 ;
2139 }
2146 /* When not optimizing, look up the slot associated with the parameter
2147 and the dimension in the cache and create a new one on failure.
2148 Don't do this when the actual subtype needs debug info (this happens
2149 with -gnatD): in elaborate_expression_1, we create variables that
2150 hold the bounds, so caching attributes isn't very interesting and
2151 causes dependency issues between these variables and cached
2152 expressions. */
2157 {
2163 {
2168 }
2169 }
2171 /* Return the cached expression or build a new one. */
2173 {
2175 {
2178 }
2180 gnu_result
2182 }
2185 {
2187 {
2190 }
2192 gnu_result
2194 }
2197 {
2199 {
2202 }
2204 gnu_result
2206 gnu_result_type);
2207 }
2209 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2210 handling. Note that these attributes could not have been used on
2211 an unconstrained array type. */
2216 /* Cache the expression we have just computed. Since we want to do it
2217 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2218 create the temporary in the outermost binding level. We will make
2219 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2220 paths by forcing its evaluation on entry of the function. */
2222 {
2223 gnu_result
2226 {
2242 }
2243 }
2245 /* Otherwise, evaluate it each time it is referenced. */
2246 else
2248 {
2251 /* If we are dereferencing a pointer to unconstrained array, we
2252 need to capture the value because the pointed-to bounds may
2253 subsequently be released. */
2255 gnu_result
2261 /* Set the source location onto the predicate of the condition
2262 but not if the expression is cached to avoid messing up the
2263 debug info. */
2267 gnat_node);
2272 }
2275 }
2282 {
2283 poly_int64 bitsize;
2284 poly_int64 bitpos;
2285 tree gnu_offset;
2286 tree gnu_field_bitpos;
2287 tree gnu_field_offset;
2288 tree gnu_inner;
2289 machine_mode mode;
2296 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2297 the result is 0. Don't allow 'Bit on a bare component, though. */
2301 {
2304 }
2306 else
2315 {
2323 {
2324 gnu_field_bitpos
2327 gnu_field_offset
2330 }
2331 }
2333 {
2336 }
2337 else
2338 {
2341 }
2344 {
2358 /* ??? Avoid a large unsigned result that will overflow when
2359 converted to the signed universal_integer. */
2362 else
2363 gnu_result
2370 }
2372 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2373 handling. */
2378 }
2382 {
2388 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2389 a NaN so we implement the semantics of C99 f{min,max} to make it
2390 predictable in this case: if either operand is a NaN, the other
2391 is returned; if both operands are NaN's, a NaN is returned. */
2394 {
2400 /* If the operands have side-effects, they need to be evaluated
2401 only once in spite of the multiple references in the result. */
2409 integer_zero_node);
2413 integer_zero_node);
2423 /* If the operands have side-effects, they need to be evaluated
2424 before doing the tests above since the place they otherwise
2425 would end up being evaluated at run time could be wrong. */
2427 gnu_result
2431 gnu_result
2433 }
2434 else
2438 }
2460 /* Note this size cannot be self-referential. */
2470 /* Return the padded size of the template in the object record type. */
2478 /* This is just a zero cast to the pointer type for our prefix and
2479 dereferenced. */
2481 gnu_result
2484 integer_zero_node));
2488 {
2495 {
2500 ;
2501 }
2509 && (DECL_BY_COMPONENT_PTR_P
2513 }
2517 /* We treat Model as identical to Machine. This is true for at least
2518 IEEE and some other nice floating-point systems. */
2520 /* ... fall through ... */
2523 /* The trick is to force the compiler to store the result in memory so
2524 that we do not have extra precision used. But do this only when this
2525 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2526 the type is lower than that of the longest floating-point type. */
2533 && fp_arith_may_widen
2536 {
2538 tree field
2548 asm_expr
2560 gnu_result
2564 }
2571 /* This can be a random address so build an alias-all pointer type. */
2572 gnu_expr
2575 gnu_expr);
2580 /* This abort means that we have an unimplemented attribute. */
2582 }
2584 /* If this is an attribute where the prefix was unused, force a use of it if
2585 it has a side-effect. But don't do it if the prefix is just an entity
2586 name. However, if an access check is needed, we must do it. See second
2587 example in AARM 11.6(5.e). */
2591 gnu_result
2596 }
2598 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Case_Statement, to a
2599 GCC tree, which is returned. */
2601 static tree
2603 {
2605 Node_Id gnat_when;
2606 location_t end_locus;
2614 /* We build a SWITCH_EXPR that contains the code with interspersed
2615 CASE_LABEL_EXPRs for each label. */
2624 {
2626 Node_Id gnat_choice;
2628 /* First compile all the different case choices for the current WHEN
2629 alternative. */
2633 {
2638 {
2653 /* This represents either a subtype range or a static value of
2654 some kind; Ekind says which. */
2656 {
2662 }
2664 /* ... fall through ... */
2676 }
2678 /* Everything should be folded into constants at this point. */
2688 gnat_choice);
2690 }
2692 /* This construct doesn't define a scope so we shouldn't push a binding
2693 level around the statement list. Except that we have always done so
2694 historically and this makes it possible to reduce stack usage. As a
2695 compromise, we keep doing it for case statements, for which this has
2696 never been problematic, but not for case expressions in Ada 2012. */
2698 {
2699 const bool is_case_expression
2701 tree group
2706 {
2711 }
2712 }
2713 }
2715 /* Now emit a definition of the label the cases branch to, if any. */
2721 }
2723 /* Return true if we are in the body of a loop. */
2727 {
2729 }
2731 /* Find out whether EXPR is a simple additive expression based on the iteration
2732 variable of some enclosing loop in the current function. If so, return the
2733 loop and set *DISP to the displacement and *NEG_P to true if this is for a
2734 subtraction; otherwise, return NULL. */
2738 {
2745 {
2751 }
2752 else
2753 {
2759 }
2773 }
2775 /* Return the innermost enclosing loop in the current function. */
2779 {
2790 }
2792 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2793 false, or the maximum value if MAX is true, of TYPE. */
2795 static bool
2797 {
2804 val = (max
2813 else
2815 }
2817 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2818 If REVERSE is true, minimum value is taken as maximum value. */
2822 {
2824 }
2826 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2827 If REVERSE is true, maximum value is taken as minimum value. */
2831 {
2833 }
2835 /* Replace EXPR1 and EXPR2 by invariant expressions if possible. Return
2836 true if both expressions have been replaced and false otherwise. */
2838 static bool
2840 {
2851 }
2853 /* Helper function for walk_tree, used by independent_iterations_p below. */
2855 static tree
2857 {
2861 /* No need to walk into types or decls. */
2869 }
2871 /* Return true if STMT_LIST generates independent iterations in a loop. */
2873 static bool
2875 {
2876 tree_stmt_iterator tsi;
2879 tree iter;
2885 /* Scan the list and return false on anything that is not either a check
2886 or an assignment to a parameter with restricted aliasing. */
2888 {
2892 {
2894 {
2903 }
2906 {
2919 }
2923 }
2924 }
2926 /* At this point we know that the list contains only statements that will
2927 modify parameters with restricted aliasing. Check that the statements
2928 don't at the time read from these parameters. */
2934 }
2936 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Loop_Statement, to a
2937 GCC tree, which is returned. */
2939 static tree
2941 {
2948 tree gnu_result;
2950 /* Push the loop_info structure associated with the LOOP_STMT. */
2955 /* Set location information for statement and end label. */
2961 /* Set the condition under which the loop must keep going. If we have an
2962 explicit condition, use it to set the location information throughout
2963 the translation of the loop statement to avoid having multiple SLOCs.
2965 For the case "LOOP .... END LOOP;" the condition is always true. */
2967 ;
2969 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2971 {
2976 }
2978 /* Otherwise we have an iteration scheme and the condition is given by the
2979 bounds of the subtype of the iteration variable. */
2980 else
2981 {
2995 /* We must disable modulo reduction for the iteration variable, if any,
2996 in order for the loop comparison to be effective. */
2998 {
3004 }
3005 else
3006 {
3012 }
3014 /* We use two different strategies to translate the loop, depending on
3015 whether optimization is enabled.
3017 If it is, we generate the canonical loop form expected by the loop
3018 optimizer and the loop vectorizer, which is the do-while form:
3020 ENTRY_COND
3021 loop:
3022 TOP_UPDATE
3023 BODY
3024 BOTTOM_COND
3025 GOTO loop
3027 This avoids an implicit dependency on loop header copying and makes
3028 it possible to turn BOTTOM_COND into an inequality test.
3030 If optimization is disabled, loop header copying doesn't come into
3031 play and we try to generate the loop form with the fewer conditional
3032 branches. First, the default form, which is:
3034 loop:
3035 TOP_COND
3036 BODY
3037 BOTTOM_UPDATE
3038 GOTO loop
3040 It should catch most loops with constant ending point. Then, if we
3041 cannot, we try to generate the shifted form:
3043 loop:
3044 TOP_COND
3045 TOP_UPDATE
3046 BODY
3047 GOTO loop
3049 which should catch loops with constant starting point. Otherwise, if
3050 we cannot, we generate the fallback form:
3052 ENTRY_COND
3053 loop:
3054 BODY
3055 BOTTOM_COND
3056 BOTTOM_UPDATE
3057 GOTO loop
3059 which works in all cases. */
3062 {
3063 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
3064 overflow. */
3066 ;
3068 /* Otherwise, use the do-while form with the help of a special
3069 induction variable in the unsigned version of the base type
3070 or the unsigned version of the size type, whichever is the
3071 largest, in order to have wrap-around arithmetics for it. */
3072 else
3073 {
3076 gnu_base_type
3078 else
3085 }
3087 gnu_first
3089 gnu_one_node);
3092 }
3093 else
3094 {
3095 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
3097 ;
3099 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
3100 GNU_LAST-1 does. */
3103 {
3104 gnu_first
3106 gnu_one_node);
3107 gnu_last
3109 gnu_one_node);
3111 }
3113 /* Otherwise, use the fallback form. */
3114 else
3116 }
3118 /* If we use the BOTTOM_COND, we can turn the test into an inequality
3119 test but we have to add ENTRY_COND to protect the empty loop. */
3121 {
3123 gnu_cond_expr
3129 }
3131 /* Open a new nesting level that will surround the loop to declare the
3132 iteration variable. */
3136 /* If we use the special induction variable, create it and set it to
3137 its initial value. Morever, the regular iteration variable cannot
3138 itself be initialized, lest the initial value wrapped around. */
3140 {
3141 gnu_loop_iv
3145 }
3146 else
3149 /* Declare the iteration variable and set it to its initial value. */
3154 {
3157 }
3162 /* Do all the arithmetics in the base type. */
3165 /* Set either the top or bottom exit condition. */
3169 gnu_last);
3170 else
3173 gnu_last);
3175 /* Set either the top or bottom update statement and give it the source
3176 location of the iteration for better coverage info. */
3178 {
3179 gnu_stmt
3186 gnu_stmt
3188 gnu_loop_iv);
3192 }
3193 else
3194 {
3195 gnu_stmt
3201 }
3204 }
3206 /* If the loop was named, have the name point to this loop. In this case,
3207 the association is not a DECL node, but the end label of the loop. */
3211 /* Make the loop body into its own block, so any allocated storage will be
3212 released every iteration. This is needed for stack allocation. */
3217 /* If we have an iteration scheme, then we are in a statement group. Add
3218 the LOOP_STMT to it, finish it and make it the "loop". */
3220 {
3221 /* First, if we have computed invariant conditions for range (or index)
3222 checks applied to the iteration variable, find out whether they can
3223 be evaluated to false at compile time; otherwise, if there are not
3224 too many of them, combine them with the original checks. If loop
3225 unswitching is enabled, do not require the loop bounds to be also
3226 invariant, as their evaluation will still be ahead of the loop. */
3229 {
3234 {
3238 {
3241 gnu_adjusted_low
3244 low_ok
3247 }
3248 else
3252 {
3255 gnu_adjusted_high
3258 high_ok
3261 }
3262 else
3265 tree range_ok
3269 rci->invariant_cond
3274 else
3275 n_remaining_checks++;
3276 }
3278 /* Note that loop unswitching can only be applied a small number of
3279 times to a given loop (PARAM_MAX_UNSWITCH_LEVEL default to 3). */
3285 {
3290 }
3291 }
3293 /* Second, if we have recorded invariants to be hoisted, emit them. */
3295 {
3300 }
3302 /* Third, if loop vectorization is enabled and the iterations of the
3303 loop can easily be proved as independent, mark the loop. */
3311 }
3313 /* If we have an outer COND_EXPR, that's our result and this loop is its
3314 "true" statement. Otherwise, the result is the LOOP_STMT. */
3316 {
3320 }
3321 else
3327 }
3329 /* This page implements a form of Named Return Value optimization modeled
3330 on the C++ optimization of the same name. The main difference is that
3331 we disregard any semantical considerations when applying it here, the
3332 counterpart being that we don't try to apply it to semantically loaded
3333 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3335 We consider a function body of the following GENERIC form:
3337 return_type R1;
3338 [...]
3339 RETURN_EXPR [<retval> = ...]
3340 [...]
3341 RETURN_EXPR [<retval> = R1]
3342 [...]
3343 return_type Ri;
3344 [...]
3345 RETURN_EXPR [<retval> = ...]
3346 [...]
3347 RETURN_EXPR [<retval> = Ri]
3348 [...]
3350 where the Ri are not addressable and we try to fulfill a simple criterion
3351 that would make it possible to replace one or several Ri variables by the
3352 single RESULT_DECL of the function.
3354 The first observation is that RETURN_EXPRs that don't directly reference
3355 any of the Ri variables on the RHS of their assignment are transparent wrt
3356 the optimization. This is because the Ri variables aren't addressable so
3357 any transformation applied to them doesn't affect the RHS; moreover, the
3358 assignment writes the full <retval> object so existing values are entirely
3359 discarded.
3361 This property can be extended to some forms of RETURN_EXPRs that reference
3362 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3363 case, in particular when function calls are involved.
3365 Therefore the algorithm is as follows:
3367 1. Collect the list of candidates for a Named Return Value (Ri variables
3368 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3369 other expressions on the RHS of such assignments.
3371 2. Prune the members of the first list (candidates) that are referenced
3372 by a member of the second list (expressions).
3374 3. Extract a set of candidates with non-overlapping live ranges from the
3375 first list. These are the Named Return Values.
3377 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3378 Named Return Values in the function with the RESULT_DECL.
3380 If the function returns an unconstrained type, things are a bit different
3381 because the anonymous return object is allocated on the secondary stack
3382 and RESULT_DECL is only a pointer to it. Each return object can be of a
3383 different size and is allocated separately so we need not care about the
3384 addressability and the aforementioned overlapping issues. Therefore, we
3385 don't collect the other expressions and skip step #2 in the algorithm. */
3387 struct nrv_data
3388 {
3389 bitmap nrv;
3390 tree result;
3391 Node_Id gnat_ret;
3393 };
3395 /* Return true if T is a Named Return Value. */
3399 {
3401 }
3403 /* Helper function for walk_tree, used by finalize_nrv below. */
3405 static tree
3407 {
3411 /* No need to walk into types or decls. */
3419 }
3421 /* Prune Named Return Values in BLOCK and return true if there is still a
3422 Named Return Value in BLOCK or one of its sub-blocks. */
3424 static bool
3426 {
3428 tree t;
3430 /* First recurse on the sub-blocks. */
3434 /* Then make sure to keep at most one NRV per block. */
3437 {
3440 else
3442 }
3445 }
3447 /* Helper function for walk_tree, used by finalize_nrv below. */
3449 static tree
3451 {
3455 /* No need to walk into types. */
3459 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3460 nop, but differs from using NULL_TREE in that it indicates that we care
3461 about the value of the RESULT_DECL. */
3464 {
3467 /* Strip useless conversions around the return value. */
3473 }
3475 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3476 if needed. */
3479 {
3483 {
3488 }
3489 else
3493 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3496 /* ??? Kludge to avoid an assertion failure during inlining. */
3499 }
3501 /* And replace all uses of NRVs with the RESULT_DECL. */
3505 /* Avoid walking into the same tree more than once. Unfortunately, we
3506 can't just use walk_tree_without_duplicates because it would only
3507 call us for the first occurrence of NRVs in the function body. */
3512 }
3514 /* Likewise, but used when the function returns an unconstrained type. */
3516 static tree
3518 {
3522 /* No need to walk into types. */
3526 /* We need to see the DECL_EXPR of NRVs before any other references so we
3527 walk the body of BIND_EXPR before walking its variables. */
3531 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3532 return value built by the allocator instead of the whole construct. */
3535 {
3538 /* This is the construct returned by the allocator. */
3541 {
3546 else
3548 }
3550 /* Strip useless conversions around the return value. */
3555 /* Strip unpadding around the return value. */
3560 /* Assign the new return value to the RESULT_DECL. */
3564 }
3566 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3567 into a new variable. */
3570 {
3577 /* Create an artificial context to build the allocation. */
3582 /* This will return a COMPOUND_EXPR with the allocation in the first
3583 arm and the final return value in the second arm. */
3590 /* The new variable is built as a reference to the allocated space. */
3591 new_var
3597 {
3600 /* The new initial value is a COMPOUND_EXPR with the allocation in
3601 the first arm and the value of P_ARRAY in the second arm. */
3607 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3614 }
3615 else
3616 {
3617 /* The new initial value is just the allocation. */
3620 }
3624 /* Destroy the artificial context and insert the new statements. */
3629 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3634 /* Save the new return value and the dereference of NEW_VAR. */
3638 /* ??? Kludge to avoid messing up during inlining. */
3640 }
3642 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3646 /* Avoid walking into the same tree more than once. Unfortunately, we
3647 can't just use walk_tree_without_duplicates because it would only
3648 call us for the first occurrence of NRVs in the function body. */
3653 }
3655 /* Apply FUNC to all the sub-trees of nested functions in NODE. FUNC is called
3656 with the DATA and the address of each sub-tree. If FUNC returns a non-NULL
3657 value, the traversal is stopped. */
3659 static void
3661 {
3664 {
3667 }
3668 }
3670 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3671 contains the candidates for Named Return Value and OTHER is a list of
3672 the other return values. GNAT_RET is a representative return node. */
3674 static void
3676 {
3678 walk_tree_fn func;
3680 tree iter;
3682 /* We shouldn't be applying the optimization to return types that we aren't
3683 allowed to manipulate freely. */
3686 /* Prune the candidates that are referenced by other return values. */
3696 /* Prune also the candidates that are referenced by nested functions. */
3701 /* Extract a set of NRVs with non-overlapping live ranges. */
3705 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3712 else
3716 }
3718 /* Return true if RET_VAL can be used as a Named Return Value for the
3719 anonymous return object RET_OBJ. */
3721 static bool
3723 {
3736 /* For the constrained case, test for addressability. */
3740 /* For the constrained case, test for overalignment. */
3744 /* For the unconstrained case, test for bogus initialization. */
3751 }
3753 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3754 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3755 around RESULT_OBJ, which may be null in this case. */
3757 static tree
3759 {
3760 tree result_expr;
3763 {
3764 /* The gimplifier explicitly enforces the following invariant:
3766 RETURN_EXPR
3767 |
3768 INIT_EXPR
3769 / \
3770 / \
3771 RET_OBJ ...
3773 As a consequence, type consistency dictates that we use the type
3774 of the RET_OBJ as the operation type. */
3777 /* Convert the right operand to the operation type. Note that this is
3778 the transformation applied in the INIT_EXPR case of build_binary_op,
3779 with the assumption that the type cannot involve a placeholder. */
3783 /* We always can use an INIT_EXPR for the return object. */
3786 /* If the function returns an aggregate type, find out whether this is
3787 a candidate for Named Return Value. If so, record it. Otherwise,
3788 if this is an expression of some kind, record it elsewhere. */
3790 && !optimize_debug
3795 {
3796 /* Strip useless conversions around the return value. */
3800 /* Now apply the test to the return value. */
3802 {
3806 }
3808 /* Note that we need not care about CONSTRUCTORs here, as they are
3809 totally transparent given the read-compose-write semantics of
3810 assignments from CONSTRUCTORs. */
3813 }
3814 }
3815 else
3819 }
3821 /* Subroutine of gnat_to_gnu to translate the At_End_Proc of GNAT_NODE, an
3822 N_Block_Statement or N_Handled_Sequence_Of_Statements or N_*_Body node.
3824 To invoked the GCC mechanism, we call add_cleanup and when we leave the
3825 group, end_stmt_group will create the TRY_FINALLY_EXPR construct. */
3827 static void
3829 {
3831 Node_Id gnat_end_label;
3833 /* When not optimizing, disable inlining of finalizers as this can
3834 create a more complex CFG in the parent function. */
3838 /* Retrieve the end label attached to the node, if any. */
3843 else
3846 /* If there is no end label attached, we use the location of the At_End
3847 procedure because Expand_Cleanup_Actions might reset the location of
3848 the enclosing construct to that of an inner statement. */
3852 }
3854 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Subprogram_Body. */
3856 static void
3858 {
3859 /* The defining identifier for the subprogram body. Note that if a
3860 specification has appeared before for this body, then the identifier
3861 occurring in that specification will also be a defining identifier
3862 and calls to this subprogram will point to that specification. */
3863 Entity_Id gnat_subprog
3866 /* The FUNCTION_DECL node corresponding to the defining identifier. */
3867 tree gnu_subprog;
3868 /* Its RESULT_DECL node. */
3869 tree gnu_result_decl;
3870 /* Its FUNCTION_TYPE node. */
3871 tree gnu_subprog_type;
3872 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3873 tree gnu_cico_list;
3874 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3875 tree gnu_return_var_elmt;
3876 /* Its source location. */
3877 location_t locus;
3879 /* If this is a generic subprogram or it has been eliminated, ignore it. */
3883 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3884 the already-elaborated tree node. However, if this subprogram had its
3885 elaboration deferred, we will already have made a tree node for it. So
3886 treat it as not being defined in that case. Such a subprogram cannot
3887 have an address clause or a freeze node, so this test is safe, though it
3888 does disable some otherwise-useful error checking. */
3889 gnu_subprog
3899 else
3902 /* If the function returns by invisible reference, make it explicit in the
3903 function body. See gnat_to_gnu_subprog_type for more details. */
3905 {
3909 }
3911 /* Set the line number in the decl to correspond to that of the body. */
3918 /* Try to create a bona-fide thunk and hand it over to the middle-end. */
3924 /* Initialize the information structure for the function. */
3933 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3934 properly copied out by the return statement. We do this by making a new
3935 block and converting any return into a goto to a label at the end of the
3936 block. */
3938 {
3939 tree gnu_return_var;
3947 /* If this is a function with copy-in/copy-out parameters and which does
3948 not return by invisible reference, we also need a variable for the
3949 return value to be placed. */
3951 {
3952 tree gnu_return_type
3955 gnu_return_var
3961 }
3962 else
3967 /* See whether there are parameters for which we don't have a GCC tree
3968 yet. These must be Out parameters. Make a VAR_DECL for them and
3969 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3970 We can match up the entries because TYPE_CI_CO_LIST is in the order
3971 of the parameters. */
3976 {
3978 tree gnu_decl;
3980 /* Skip any entries that have been already filled in; they must
3981 correspond to In Out parameters. */
3985 /* Do any needed dereferences for by-ref objects. */
3991 /* Do any needed references for padded types. */
3994 }
3995 }
3996 else
3999 /* Get a tree corresponding to the code for the subprogram. */
4003 /* First translate the declarations of the subprogram. */
4006 /* Then generate the code of the subprogram itself. A return statement will
4007 be present and any Out parameters will be handled there. */
4010 /* Process the At_End_Proc, if any. */
4017 /* Attempt setting the end_locus of our GCC body tree, typically a BIND_EXPR,
4018 then the end_locus of our GCC subprogram declaration tree. */
4022 /* If we populated the parameter attributes cache, we need to make sure that
4023 the cached expressions are evaluated on all the possible paths leading to
4024 their uses. So we force their evaluation on entry of the function. */
4027 {
4034 {
4041 }
4047 }
4049 /* If we are dealing with a return from an Ada procedure with parameters
4050 passed by copy-in/copy-out, we need to return a record containing the
4051 final values of these parameters. If the list contains only one entry,
4052 return just that entry though.
4054 For a full description of the copy-in/copy-out parameter mechanism, see
4055 the part of the gnat_to_gnu_entity routine dealing with the translation
4056 of subprograms.
4058 We need to make a block that contains the definition of that label and
4059 the copying of the return value. It first contains the function, then
4060 the label and copy statement. */
4062 {
4063 const Node_Id gnat_end_label
4072 /* If this is a function which returns by invisible reference, the
4073 return value has already been dealt with at the return statements,
4074 so we only need to indirectly copy out the parameters. */
4076 {
4077 tree gnu_ret_deref
4079 tree t;
4084 {
4085 tree gnu_field_deref
4090 }
4091 }
4093 /* Otherwise, if this is a procedure or a function which does not return
4094 by invisible reference, we can do a direct block-copy out. */
4095 else
4096 {
4097 tree gnu_retval;
4101 else
4102 gnu_retval
4104 gnu_cico_list);
4108 }
4112 }
4116 /* On SEH targets, install an exception handler around the main entry
4117 point to catch unhandled exceptions. */
4120 {
4121 tree t;
4122 tree etype;
4134 }
4138 /* Finally annotate the parameters and disconnect the trees for parameters
4139 that we have turned into variables since they are now unusable. */
4143 {
4152 }
4154 /* Disconnect the variable created for the return value. */
4158 /* If the function returns an aggregate type and we have candidates for
4159 a Named Return Value, finalize the optimization. */
4161 {
4168 }
4170 /* If this is an inlined external function that has been marked uninlinable,
4171 drop the body and stop there. Otherwise compile the body. */
4174 else
4176 }
4178 /* The type of an atomic access. */
4182 /* Return true if GNAT_NODE references an Atomic entity. This is modeled on
4183 the Is_Atomic_Object predicate of the front-end, but additionally handles
4184 explicit dereferences. */
4186 static bool
4188 {
4189 Entity_Id gnat_entity;
4192 {
4217 }
4220 }
4222 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. This is
4223 modeled on the Is_Volatile_Full_Access_Object predicate of the front-end,
4224 but additionally handles explicit dereferences. */
4226 static bool
4228 {
4229 Entity_Id gnat_entity;
4232 {
4252 }
4255 }
4257 /* Return true if GNAT_NODE references a component of a larger object. */
4261 {
4263 return
4265 }
4267 /* Compute whether GNAT_NODE requires atomic access and set TYPE to the type
4268 of access and SYNC according to the associated synchronization setting.
4270 We implement 3 different semantics of atomicity in this function:
4272 1. the Ada 95/2005/2012 semantics of the Atomic aspect/pragma,
4273 2. the Ada 2022 semantics of the Atomic aspect/pragma,
4274 3. the semantics of the Volatile_Full_Access GNAT aspect/pragma.
4276 They are mutually exclusive and the FE should have rejected conflicts. */
4278 static void
4280 {
4284 /* First, scan the parent to filter out irrelevant cases. */
4287 {
4290 /* Do not mess up machine code insertions. */
4294 /* Nothing to do if we are the prefix of an attribute, since we do not
4295 want an atomic access for things like 'Size. */
4297 /* ... fall through ... */
4300 /* The N_Reference node is like an attribute. */
4306 /* Nothing to do for the identifier in an object renaming declaration,
4307 the renaming itself does not need atomic access. */
4312 }
4314 /* Now strip any type conversion from GNAT_NODE. */
4319 /* Up to Ada 2012, for Atomic itself, only reads and updates of the object as
4320 a whole require atomic access (RM C.6(15)). But, starting with Ada 2022,
4321 reads of or writes to a nonatomic subcomponent of the object also require
4322 atomic access (RM C.6(19)). */
4324 {
4327 /* If we are the prefix of the parent, then the access is partial. */
4333 else
4336 /* We consider that partial accesses are not sequential actions and,
4337 therefore, do not require synchronization. */
4341 }
4343 /* Look for an outer atomic access of a nonatomic subcomponent. Note that,
4344 for VFA, we do this before looking at the node itself because we need to
4345 access the outermost VFA object atomically, unlike for Atomic where it is
4346 the innermost atomic object (RM C.6(19)). */
4352 {
4356 }
4358 /* Unlike Atomic, accessing a VFA object always requires atomic access. */
4360 {
4364 }
4366 not_atomic:
4369 }
4371 /* Return true if GNAT_NODE requires simple atomic access and, if so, set SYNC
4372 according to the associated synchronization setting. */
4376 {
4377 atomic_acces_t type;
4380 }
4382 /* Return the storage model specified by GNAT_NODE, or else Empty. */
4384 static Entity_Id
4386 {
4390 else
4392 }
4394 /* Compute whether GNAT_NODE requires storage model access and set GNAT_SMO to
4395 the storage model object to be used for it if it does, or else Empty. */
4397 static void
4399 {
4404 {
4406 /* If the parent is an attribute reference that requires an lvalue and
4407 gnat_node is the Prefix (i.e. not a parameter), we do not need to
4408 actually access any storage. */
4415 /* Nothing to do for the identifier in an object renaming declaration,
4416 the renaming itself does not need storage model access. */
4421 }
4423 /* If we are the prefix of the parent, then the access is above us. */
4427 /* Now strip any type conversion from GNAT_NODE. */
4436 }
4438 /* Return true if GNAT_NODE requires storage model access and, if so, set
4439 GNAT_SMO to the storage model object to be used for it. */
4441 static bool
4443 {
4446 }
4448 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4450 static tree
4452 {
4453 tree gnu_temp
4459 }
4461 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4462 Put the initialization statement into GNU_INIT_STMT and annotate it with
4463 the SLOC of GNAT_NODE. Return the temporary variable. */
4465 static tree
4467 Node_Id gnat_node)
4468 {
4475 }
4477 /* Return true if TYPE is an array of scalar type. */
4479 static bool
4481 {
4488 }
4490 /* Helper function for walk_tree, used by return_slot_opt_for_pure_call_p. */
4492 static tree
4494 {
4504 }
4506 /* Return whether the assignment TARGET = CALL can be subject to the return
4507 slot optimization, under the assumption that the called function be pure
4508 in the Ada sense and return an array of scalar type. */
4510 static bool
4512 {
4513 /* Check that the target is a DECL. */
4518 call_expr_arg_iterator iter;
4519 tree arg;
4521 /* Check that all the arguments have either a scalar type (we assume that
4522 this means by-copy passing mechanism) or array of scalar type. */
4524 {
4534 }
4536 /* Check that the target is not referenced by the non-scalar arguments. */
4538 }
4540 /* Elaborate types referenced in the profile (FIRST_FORMAL, RESULT_TYPE). */
4542 static void
4544 {
4545 Entity_Id formal;
4554 }
4556 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Function_Call
4557 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4558 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4559 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4560 N_Assignment_Statement and the result is to be placed into that object.
4561 ATOMIC_ACCESS is the type of atomic access to be used for the assignment
4562 to GNU_TARGET. If, in addition, ATOMIC_SYNC is true, then the assignment
4563 to GNU_TARGET requires atomic synchronization. GNAT_SMO is the storage
4564 model object to be used for the assignment to GNU_TARGET or Empty if there
4565 is none. */
4567 static tree
4570 {
4573 /* The GCC node corresponding to the GNAT subprogram name. This can either
4574 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4575 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4576 subprogram. */
4579 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4581 /* The return type of the FUNCTION_TYPE. */
4582 tree gnu_result_type;;
4583 const bool frontend_builtin
4596 Entity_Id gnat_formal;
4597 Entity_Id gnat_result_type;
4598 Node_Id gnat_actual;
4599 atomic_acces_t aa_type;
4602 /* The only way we can make a call via an access type is if GNAT_NAME is an
4603 explicit dereference. In that case, get the list of formal args from the
4604 type the access type is pointing to. Otherwise, get the formals from the
4605 entity being called. */
4607 {
4608 const Entity_Id gnat_prefix_type
4615 /* If the access type doesn't require foreign-compatible representation,
4616 be prepared for descriptors. */
4617 by_descriptor
4620 }
4623 {
4624 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4629 }
4631 else
4632 {
4640 /* If we are calling a stubbed function, then raise Program_Error, but
4641 elaborate all our args first. */
4643 {
4653 {
4657 }
4660 }
4661 }
4663 /* We must elaborate the entire profile now because, if it references types
4664 that were initially incomplete,, their elaboration changes the contents
4665 of GNU_SUBPROG_TYPE and, in particular, may change the result type. */
4672 {
4673 /* For a call to a nested function, check the inlining status. */
4677 /* For a recursive call, avoid explosion due to recursive inlining. */
4680 }
4682 /* The lifetime of the temporaries created for the call ends right after the
4683 return value is copied, so we can give them the scope of the elaboration
4684 routine at top level. */
4686 {
4689 }
4690 else
4693 /* First, create the temporary for the return value when:
4695 1. There is no target and the function has copy-in/copy-out parameters,
4696 because we need to preserve the return value before copying back the
4697 parameters.
4699 2. There is no target and the call is made for neither the declaration
4700 of an object (regular or renaming), nor a return statement, nor an
4701 allocator, nor an aggregate, and the return type has variable size
4702 because in this case the gimplifier cannot create the temporary, or
4703 more generally is an aggregate type, because the gimplifier would
4704 create the temporary in the outermost scope instead of locally here.
4705 But there is an exception for an allocator of unconstrained record
4706 type with default discriminant because we allocate the actual size
4707 in this case, unlike in the other cases, so we need a temporary to
4708 fetch the discriminant and we create it here.
4710 3. There is a target and it is a slice or an array with fixed size,
4711 and the return type has variable size, because the gimplifier
4712 doesn't handle these cases.
4714 4. There is a target which is a bit-field and the function returns an
4715 unconstrained record type with default discriminant, because the
4716 return may copy more data than the bit-field can contain.
4718 5. There is a target which needs to be accessed with a storage model.
4720 6. There is no target and we have misaligned In Out or Out parameters
4721 passed by reference, because we need to preserve the return value
4722 before copying back the parameters. However, in this case, we'll
4723 defer creating the temporary, see below.
4725 This must be done before we push a binding level around the call, since
4726 we will pop it before copying the return value. */
4729 || (!gnu_target
4739 || (gnu_target
4745 || (gnu_target
4751 || (gnu_target
4754 {
4757 }
4759 /* If we don't need a value or have already created it, push a binding level
4760 around the call. This will narrow the lifetime of the temporaries we may
4761 need to make when translating the parameters as much as possible. */
4763 {
4767 }
4768 else
4771 /* Create the list of the actual parameters as GCC expects it, namely a
4772 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4773 is an expression and the TREE_PURPOSE field is null. But skip Out
4774 parameters not passed by reference and that need not be copied in. */
4779 {
4785 const bool is_true_formal_parm
4787 const bool is_by_ref_formal_parm
4788 = is_true_formal_parm
4791 /* In the In Out or Out case, we must suppress conversions that yield
4792 an lvalue but can nevertheless cause the creation of a temporary,
4793 because we need the real object in this case, either to pass its
4794 address if it's passed by reference or as target of the back copy
4795 done after the call if it uses the copy-in/copy-out mechanism.
4796 We do it in the In case too, except for an unchecked conversion
4797 to an elementary type or a constrained composite type because it
4798 alone can cause the actual to be misaligned and the addressability
4799 test is applied to the real object. */
4800 const bool suppress_type_conversion
4802 && (!in_param
4803 || !is_by_ref_formal_parm
4808 Node_Id gnat_name = suppress_type_conversion
4812 /* If it's possible we may need to use this expression twice, make sure
4813 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4814 to force side-effects before the call. */
4816 {
4820 gnu_name
4822 }
4824 /* If we are passing a non-addressable parameter by reference, pass the
4825 address of a copy. In the In Out or Out case, set up to copy back
4826 out after the call. */
4830 {
4833 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4834 but sort of an instantiation for them. */
4836 ;
4838 /* If the formal is passed by reference, a copy is not allowed. */
4842 gnat_actual);
4844 /* If the mechanism was forced to by-ref, a copy is not allowed but
4845 we issue only a warning because this case is not strict Ada. */
4848 gnat_actual);
4850 /* If the actual type of the object is already the nominal type,
4851 we have nothing to do, except if the size is self-referential
4852 in which case we'll remove the unpadding below. */
4855 ;
4857 /* Otherwise remove the unpadding from all the objects. */
4859 && TYPE_IS_PADDING_P
4863 /* Otherwise convert to the nominal type of the object if needed.
4864 There are several cases in which we need to make the temporary
4865 using this type instead of the actual type of the object when
4866 they are distinct, because the expectations of the callee would
4867 otherwise not be met:
4868 - if it's a justified modular type,
4869 - if the actual type is a smaller form of it,
4870 - if it's a smaller form of the actual type. */
4874 gnu_name_type)))
4880 /* If this is an In Out or Out parameter and we're returning a value,
4881 we need to create a temporary for the return value because we must
4882 preserve it before copying back at the very end. */
4884 {
4887 }
4889 /* If we haven't pushed a binding level, push it now. This will
4890 narrow the lifetime of the temporary we are about to make as
4891 much as possible. */
4893 {
4897 }
4899 /* Create an explicit temporary holding the copy. */
4901 /* Do not initialize it for the _Init parameter of an initialization
4902 procedure since no data is meant to be passed in. */
4908 /* Initialize it on the fly like for an implicit temporary in the
4909 other cases, as we don't necessarily have a statement list. */
4910 else
4911 {
4913 gnat_actual);
4915 gnu_temp);
4916 }
4918 /* Set up to move the copy back to the original if needed. */
4920 {
4921 /* If the original is a COND_EXPR whose first arm isn't meant to
4922 be further used, just deal with the second arm. This is very
4923 likely the conditional expression built for a check. */
4926 && integer_zerop
4930 gnu_stmt
4935 }
4936 }
4938 /* Start from the real object and build the actual. */
4941 /* If atomic access is required for an In or In Out actual parameter,
4942 build the atomic load. */
4944 && !is_by_ref_formal_parm
4949 /* If this was a procedure call, we may not have removed any padding.
4950 So do it here for the part we will use as an input, if any. */
4953 gnu_actual
4956 /* Put back the conversion we suppressed above in the computation of the
4957 real object. And even if we didn't suppress any conversion there, we
4958 may have suppressed a conversion to the Etype of the actual earlier,
4959 since the parent is a procedure call, so put it back here. Note that
4960 we might have a dummy type here if the actual is the dereference of a
4961 pointer to it, but that's OK when the formal is passed by reference.
4962 We also do not put back a conversion between an actual and a formal
4963 that are unconstrained array types to avoid creating local bounds. */
4975 ;
4976 else
4981 /* First see if the parameter is passed by reference. */
4983 {
4985 {
4986 /* In Out or Out parameters passed by reference don't use the
4987 copy-in/copy-out mechanism so the address of the real object
4988 must be passed to the function. */
4991 /* If we have a padded type, be sure we've removed padding. */
4994 gnu_actual);
4996 /* If we have the constructed subtype of an aliased object
4997 with an unconstrained nominal subtype, the type of the
4998 actual includes the template, although it is formally
4999 constrained. So we need to convert it back to the real
5000 constructed subtype to retrieve the constrained part
5001 and takes its address. */
5007 }
5009 /* There is no need to convert the actual to the formal's type before
5010 taking its address. The only exception is for unconstrained array
5011 types because of the way we build fat pointers. */
5013 {
5014 /* Put back the conversion we suppressed above for In Out or Out
5015 parameters, since it may set the bounds of the actual. */
5019 }
5021 /* Take the address of the object and convert to the proper pointer
5022 type. */
5025 }
5027 /* Then see if the parameter is an array passed to a foreign convention
5028 subprogram. */
5030 {
5034 /* Take the address of the object and convert to the proper pointer
5035 type. We'd like to actually compute the address of the beginning
5036 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
5037 possibility that the ARRAY_REF might return a constant and we'd be
5038 getting the wrong address. Neither approach is exactly correct,
5039 but this is the most likely to work in all cases. */
5042 }
5044 /* Then see if the parameter is passed by copy. */
5046 {
5052 /* If this is a front-end built-in function, there is no need to
5053 convert to the type used to pass the argument. */
5056 }
5058 /* Then see if this is an unnamed parameter in a variadic C function. */
5060 {
5061 /* This is based on the processing done in gnat_to_gnu_param, but
5062 we expect the mechanism to be set in (almost) all cases. */
5065 /* Strip off possible padding type. */
5069 /* Arrays are passed as pointers to element type. First check for
5070 unconstrained array and get the underlying array. */
5072 gnu_formal_type
5073 = TREE_TYPE
5076 /* Arrays are passed as pointers to element type. */
5078 {
5082 /* Strip off any multi-dimensional entries, then strip
5083 off the last array to get the component type. */
5090 gnu_actual
5092 }
5094 /* Fat pointers are passed as thin pointers. */
5096 gnu_formal_type
5100 /* If we were requested or muss pass by reference, do so.
5101 If we were requested to pass by copy, do so.
5102 Otherwise, pass In Out or Out parameters or aggregates by
5103 reference. */
5108 {
5110 gnu_actual
5112 }
5114 /* Otherwise pass by copy after applying default C promotions. */
5115 else
5116 {
5126 }
5129 }
5131 /* If we didn't create a PARM_DECL for the formal, this means that
5132 it is an Out parameter not passed by reference and that need not
5133 be copied in. In this case, the value of the actual need not be
5134 read. However, we still need to make sure that its side-effects
5135 are evaluated before the call, so we evaluate its address. */
5136 else
5137 {
5142 {
5145 }
5148 }
5151 }
5154 {
5159 {
5170 }
5174 gnu_call
5176 icode,
5177 gnu_result_type,
5180 }
5181 else
5182 {
5183 gnu_call
5185 gnu_result_type,
5187 gnu_subprog),
5191 }
5195 /* If we have created a temporary for the return value, initialize it. */
5197 {
5198 tree gnu_stmt
5203 }
5205 /* If this is a subprogram with copy-in/copy-out parameters, we need to
5206 unpack the valued returned from the function into the In Out or Out
5207 parameters. We deal with the function return (if this is an Ada
5208 function) below. */
5210 {
5211 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
5212 copy-out parameters. */
5216 /* The call sequence must contain one and only one call, even though the
5217 function is pure. Save the result into a temporary if needed. */
5219 {
5221 {
5222 tree gnu_stmt;
5223 gnu_call
5226 }
5229 }
5231 /* The first entry is for the actual return value if this is a
5232 function, so skip it. */
5238 else
5245 /* If we are dealing with a copy-in/copy-out parameter, we must
5246 retrieve its value from the record returned in the call. */
5252 {
5253 /* Get the value to assign to this In Out or Out parameter. It is
5254 either the result of the function if there is only a single such
5255 parameter or the appropriate field from the record returned. */
5256 tree gnu_result
5258 ? gnu_call
5262 /* If the actual is a conversion, get the inner expression, which
5263 will be the real destination, and convert the result to the
5264 type of the actual parameter. */
5265 tree gnu_actual
5268 /* If the result is padded, remove the padding. */
5271 /* If the actual is a type conversion, the real target object is
5272 denoted by the inner Expression and we need to convert the
5273 result to the associated type.
5274 We also need to convert our gnu assignment target to this type
5275 if the corresponding GNU_NAME was constructed from the GNAT
5276 conversion node and not from the inner Expression. */
5278 {
5283 gnu_result
5287 gnat_actual);
5291 }
5293 /* Unchecked conversions as actuals for Out parameters are not
5294 allowed in user code because they are not variables, but do
5295 occur in front-end expansions. The associated GNU_NAME is
5296 always obtained from the inner expression in such cases. */
5299 gnu_result,
5301 else
5302 {
5308 }
5312 /* If an outer atomic access is required for an actual parameter,
5313 build the load-modify-store sequence. */
5315 gnu_result
5318 /* Or else, if a simple atomic access is required, build the atomic
5319 store. */
5321 gnu_result
5324 /* Otherwise build a regular assignment. */
5325 else
5334 }
5335 }
5337 /* If this is a function call, the result is the call expression unless a
5338 target is specified, in which case we copy the result into the target
5339 and return the assignment statement. */
5341 {
5342 /* If this is a function with copy-in/copy-out parameters, extract the
5343 return value from it and update the return type. */
5345 {
5347 gnu_call
5350 }
5352 /* If the function returns by direct reference, we have to dereference
5353 the pointer. */
5358 {
5364 /* ??? If the return type has variable size, then force the return
5365 slot optimization as we would not be able to create a temporary.
5366 That's what has been done historically. */
5370 /* If this is a call to a pure function returning an array of scalar
5371 type, try to apply the return slot optimization. */
5380 /* If this is the initialization of a return object in a function
5381 returning by invisible reference, we can always use the return
5382 slot optimization. */
5385 && current_function_decl
5389 else
5392 /* Use the required method to move the result to the target. */
5394 gnu_call
5400 gnu_call
5402 else
5403 gnu_call
5409 }
5410 else
5412 }
5414 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
5415 parameters, the result is just the call statement. */
5419 /* Finally, add the copy back statements, if any. */
5425 /* If we have pushed a binding level, pop it and finish up the enclosing
5426 statement group. */
5428 {
5432 }
5434 /* Otherwise, retrieve the statement list, if any. */
5438 /* Otherwise, just return the call expression. */
5439 else
5442 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
5443 But first simplify if we have only one statement in the list. */
5445 {
5449 gnu_result
5451 }
5454 }
5456 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an
5457 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
5459 static tree
5461 {
5462 /* If just annotating, ignore all EH and cleanups. */
5463 const bool eh
5466 tree gnu_result;
5467 Node_Id gnat_temp;
5469 /* The exception handling mechanism can handle both ZCX and SJLJ schemes, and
5470 is exposed through the TRY_CATCH_EXPR construct that we build manually.
5472 ??? The region level calls down there have been specifically put in place
5473 for a ZCX context and currently the order in which things are emitted
5474 (region/handlers) is different from the SJLJ case. Instead of putting
5475 other calls with different conditions at other places for the SJLJ case,
5476 it seems cleaner to reorder things for the SJLJ case and generalize the
5477 condition to make it not ZCX specific. */
5479 /* First build the tree for the statements inside the sequence. */
5489 /* Then process the exception handlers, if any. */
5491 {
5492 tree gnu_handlers;
5493 location_t locus;
5495 /* First make a group containing the handlers. */
5503 /* Now make the TRY_CATCH_EXPR for the group. */
5504 gnu_result
5507 /* Set a location. We need to find a unique location for the dispatching
5508 code, otherwise we can get coverage or debugging issues. Try with
5509 the location of the end label. */
5513 else
5514 /* Clear column information so that the exception handler of an
5515 implicit transient block does not incorrectly inherit the slocs
5516 of a decision, which would otherwise confuse control flow based
5517 coverage analysis tools. */
5519 }
5521 /* Process the At_End_Proc, if any. */
5523 {
5528 }
5531 }
5533 /* Return true if no statement in GNAT_LIST can alter the control flow. */
5535 static bool
5537 {
5541 /* This is very conservative, we reject everything except for simple
5542 assignments between identifiers or literals. */
5546 {
5558 }
5561 }
5563 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Exception_Handler,
5564 to a GCC tree, which is returned. */
5566 static tree
5568 {
5571 /* We build a TREE_LIST of nodes representing what exception types this
5572 handler can catch, with special cases for others and all others cases.
5574 Each exception type is actually identified by a pointer to the exception
5575 id, or to a dummy object for "others" and "all others". */
5577 gnat_temp;
5579 {
5583 {
5586 }
5589 {
5592 /* Exception may be a renaming. Recover original exception which is
5593 the one elaborated and registered. */
5599 }
5600 else
5603 /* The GCC interface expects NULL to be passed for catch all handlers, so
5604 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5605 is integer_zero_node. It would not work, however, because GCC's
5606 notion of "catch all" is stronger than our notion of "others". Until
5607 we correctly use the cleanup interface as well, doing that would
5608 prevent the "all others" handlers from being seen, because nothing
5609 can be caught beyond a catch all from GCC's point of view. */
5611 }
5615 /* Expand a call to the begin_handler hook at the beginning of the
5616 handler, and arrange for a call to the end_handler hook to occur
5617 on every possible exit path. GDB sets a breakpoint in the
5618 begin_handler for catchpoints.
5620 A v1 begin handler saves the cleanup from the exception object,
5621 and marks the exception as in use, so that it will not be
5622 released by other handlers. A v1 end handler restores the
5623 cleanup and releases the exception object, unless it is still
5624 claimed, or the exception is being propagated (reraised).
5626 __builtin_eh_pointer references the exception occurrence being
5627 handled or propagated. Within the handler region, it is the
5628 former, but within the else branch of the EH_ELSE_EXPR, i.e. the
5629 exceptional cleanup path, it is the latter, so we must save the
5630 occurrence being handled early on, so that, should an exception
5631 be (re)raised, we can release the current exception, or figure
5632 out we're not to release it because we're propagating a reraise
5633 thereof.
5635 We use local variables to retrieve the incoming value at handler
5636 entry time (EXPTR), the saved cleanup (EXCLN) and the token
5637 (EXVTK), and reuse them to feed the end_handler hook's argument
5638 at exit. */
5640 /* CODE: void *EXPTR = __builtin_eh_pointer (0); */
5641 tree gnu_current_exc_ptr
5644 tree exc_ptr
5653 /* begin_handler_decl must not throw, so we can use it as an
5654 initializer for a variable used in cleanups.
5656 CODE: void *EXCLN = __gnat_begin_handler_v1 (EXPTR); */
5657 tree exc_cleanup
5659 ptr_type_node,
5661 exc_ptr),
5665 /* Declare and initialize the choice parameter, if present. */
5667 {
5668 tree gnu_param
5671 /* CODE: __gnat_set_exception_parameter (&choice_param, EXPTR); */
5675 gnu_incoming_exc_ptr));
5676 }
5678 /* CODE: <handler proper> */
5682 exc_ptr,
5683 exc_cleanup,
5684 null_pointer_node);
5685 /* If the handler can only end by falling off the end, don't bother
5686 with cleanups. */
5688 /* CODE: __gnat_end_handler_v1 (EXPTR, EXCLN, NULL); */
5690 /* Otherwise, all of the above is after
5691 CODE: try {
5693 The call above will appear after
5694 CODE: } finally {
5696 And the code below will appear after
5697 CODE: } else {
5699 The else block to a finally block is taken instead of the finally
5700 block when an exception propagates out of the try block. */
5701 else
5702 {
5705 /* CODE: void *EXPRP = __builtin_eh_handler (0); */
5706 tree prop_ptr
5708 ptr_type_node,
5715 /* CODE: __gnat_end_handler_v1 (EXPTR, EXCLN, EXPRP); */
5717 exc_ptr,
5718 exc_cleanup,
5719 prop_ptr);
5723 /* CODE: } */
5727 }
5731 return
5733 }
5735 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Compilation_Unit. */
5737 static void
5739 {
5744 Entity_Id gnat_entity;
5746 /* Make the decl for the elaboration procedure. Emit debug info for it, so
5747 that users can break into their elaboration code in debuggers. Kludge:
5748 don't consider it as a definition so that we have a line map for its
5749 body, but no subprogram description in debug info. In addition, don't
5750 qualify it as artificial, even though it is not a user subprogram per se,
5751 in particular for specs. Unlike, say, clones created internally by the
5752 compiler, this subprogram materializes specific user code and flagging it
5753 artificial would take elab code away from gcov's analysis. */
5754 tree gnu_elab_proc_decl
5755 = create_subprog_decl
5764 /* Initialize the information structure for the function. */
5773 /* For a body, first process the spec if there is one. */
5779 {
5786 }
5788 /* Then process any pragmas and declarations preceding the unit. */
5797 /* Process the unit itself. */
5800 /* Generate code for all the inlined subprograms. */
5804 {
5805 Node_Id gnat_body;
5807 /* Without optimization, process only the required subprograms. */
5811 /* The set of inlined subprograms is computed from data recorded early
5812 during expansion and it can be a strict superset of the final set
5813 computed after semantic analysis, for example if a call to such a
5814 subprogram occurs in a pragma Assert and assertions are disabled.
5815 In that case, semantic analysis resets Is_Public to false but the
5816 entry for the subprogram in the inlining tables is stalled. */
5822 {
5823 /* ??? This happens when only the spec of a package is provided. */
5827 gnat_body
5829 }
5831 /* Define the entity first so we set DECL_EXTERNAL. */
5834 }
5836 /* Process any pragmas and actions following the unit. */
5841 /* Then process the expressions of pragma Compile_Time_{Error|Warning} to
5842 annotate types referenced therein if they have not been annotated. */
5847 /* Save away what we've made so far and finish it up. */
5854 /* Record this potential elaboration procedure for later processing. */
5861 /* Force the processing for all nodes that remain in the queue. */
5863 }
5865 /* Mark COND, a boolean expression, as predicating a call to a noreturn
5866 function, i.e. predict that it is very likely false, and return it.
5868 The compiler will automatically predict the last edge leading to a call
5869 to a noreturn function as very unlikely taken. This function makes it
5870 possible to extend the prediction to predecessors in case the condition
5871 is made up of several short-circuit operators. */
5873 static tree
5875 {
5877 return
5881 }
5883 /* Subroutine of gnat_to_gnu to translate GNAT_RANGE, a node representing a
5884 range of values, into GNU_LOW and GNU_HIGH bounds. */
5886 static void
5888 {
5889 /* GNAT_RANGE is either an N_Range or an identifier denoting a subtype. */
5891 {
5899 {
5903 *gnu_low
5905 *gnu_high
5907 }
5912 }
5913 }
5915 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Raise_xxx_Error,
5916 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
5917 where we should place the result type. */
5919 static tree
5921 {
5925 const bool with_extra_info
5926 = Exception_Extra_Info
5930 Node_Id gnat_rcond;
5932 /* The following processing is not required for correctness. Its purpose is
5933 to give more precise error messages and to record some information. */
5935 {
5950 {
5960 {
5978 }
5982 {
5986 }
5991 gnu_result
5995 /* If optimization is enabled and we are inside a loop, we try to
5996 compute invariant conditions for checks applied to the iteration
5997 variable, i.e. conditions that are independent of the variable
5998 and necessary in order for the checks to fail in the course of
5999 some iteration. If we succeed, we consider an alternative:
6001 1. If loop unswitching is enabled, we prepend these conditions
6002 to the original conditions of the checks. This will make it
6003 possible for the loop unswitching pass to replace the loop
6004 with two loops, one of which has the checks eliminated and
6005 the other has the original checks reinstated, and a prologue
6006 implementing a run-time selection. The former loop will be
6007 for example suitable for vectorization.
6009 2. Otherwise, we instead append the conditions to the original
6010 conditions of the checks. At worse, if the conditions cannot
6011 be evaluated at compile time, they will be evaluated as true
6012 at run time only when the checks have already failed, thus
6013 contributing negatively only to the size of the executable.
6014 But the hope is that these invariant conditions be evaluated
6015 at compile time to false, thus taking away the entire checks
6016 with them. */
6019 && (!gnu_low_bound
6021 && (!gnu_high_bound
6024 {
6031 rci->inserted_cond
6037 boolean_type_node,
6039 gnu_cond);
6040 else
6042 boolean_type_node,
6043 gnu_cond,
6045 }
6046 }
6051 }
6053 /* The following processing does the real work, but we must nevertheless make
6054 sure not to override the result of the previous processing. */
6061 /* If the type is VOID, this is a statement, so we need to generate the code
6062 for the call. Handle a condition, if there is one. */
6064 {
6066 {
6073 }
6074 }
6075 else
6076 {
6077 /* The condition field must not be present when the node is used as an
6078 expression form. */
6081 }
6084 }
6086 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
6087 parameter of a call. */
6089 static bool
6091 {
6106 }
6108 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
6109 of an assignment or an actual parameter of a call. */
6111 static bool
6113 {
6124 }
6126 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
6127 as gigi is concerned. This is used to avoid conversions on the LHS. */
6129 static bool
6131 {
6134 /* The conversion must be on the LHS of an assignment or an actual parameter
6135 of a call. Otherwise, even if the conversion was essentially a no-op, it
6136 could de facto ensure type consistency and this should be preserved. */
6142 /* We're interested in artificial conversions generated by the front-end
6143 to make private types explicit, e.g. in Expand_Assign_Array. */
6150 /* The direct conversion to the underlying type is a no-op. */
6154 /* For an array subtype, the conversion to the PAIT is a no-op. */
6159 /* For a record subtype, the conversion to the type is a no-op. */
6165 }
6167 /* Return true if GNAT_NODE represents a statement. */
6169 static bool
6171 {
6187 }
6189 /* This function is the driver of the GNAT to GCC tree transformation process.
6190 It is the entry point of the tree transformer. GNAT_NODE is the root of
6191 some GNAT tree. Return the root of the corresponding GCC tree. If this
6192 is an expression, return the GCC equivalent of the expression. If this
6193 is a statement, return the statement or add it to the current statement
6194 group, in which case anything returned is to be interpreted as occurring
6195 after anything added. */
6197 tree
6199 {
6204 Node_Id gnat_temp;
6205 atomic_acces_t aa_type;
6208 Entity_Id gnat_smo;
6210 /* Save node number for error message and set location information. */
6215 /* If we are only annotating types and this node is a statement, return
6216 an empty statement list. */
6220 /* If we are only annotating types and this node is a subexpression, return
6221 a NULL_EXPR, but filter out nodes appearing in the expressions attached
6222 to packed array implementation types. */
6238 N_Raise_Constraint_Error));
6240 /* If this is a statement and we are at top level, it must be part of the
6241 elaboration procedure, so mark us as being in that procedure. */
6246 {
6249 }
6250 else
6254 {
6255 /********************************/
6256 /* Chapter 2: Lexical Elements */
6257 /********************************/
6266 /* If atomic access is required on the RHS, build the atomic load. */
6273 {
6274 tree gnu_type;
6276 /* Get the type of the result, looking inside any padding and
6277 justified modular types. Then get the value in that type. */
6286 /* If the result overflows (meaning it doesn't fit in its base type),
6287 abort, unless this is for a named number because that's not fatal.
6288 We would like to check that the value is within the range of the
6289 subtype, but that causes problems with subtypes whose usage will
6290 raise Constraint_Error and also with biased representation. */
6292 {
6295 else
6297 }
6298 }
6302 /* If a Entity is present, it means that this was one of the
6303 literals in a user-defined character type. In that case,
6304 just return the value in the CONST_DECL. Otherwise, use the
6305 character code. In that case, the base type should be an
6306 INTEGER_TYPE, but we won't bother checking for that. */
6310 else
6311 gnu_result
6319 /* If this is of a fixed-point type, the value we want is the value of
6320 the corresponding integer. */
6322 {
6324 gnu_result_type);
6326 }
6328 else
6329 {
6332 /* First convert the value to a machine number if it isn't already.
6333 That will force the base to 2 for non-zero values and simplify
6334 the rest of the logic. */
6336 ur_realval
6342 else
6343 {
6344 REAL_VALUE_TYPE tmp;
6348 /* The base must be 2 as Machine guarantees this, so we scale
6349 the value, which we know can fit in the mantissa of the type
6350 (hence the use of that type above). */
6355 }
6357 /* Now see if we need to negate the result. Do it this way to
6358 properly handle -0. */
6360 gnu_result
6362 gnu_result);
6363 }
6370 {
6377 else
6380 /* Build the string with the characters in the literal. Note
6381 that Ada strings are 1-origin. */
6387 /* Strings in GCC don't normally have types, but we want
6388 this to not be converted to the array type. */
6393 }
6394 else
6395 {
6396 /* Build a list consisting of each character, then make
6397 the aggregate. */
6407 {
6413 }
6416 }
6423 /**************************************/
6424 /* Chapter 3: Declarations and Types */
6425 /**************************************/
6443 /* If we are just annotating types and this object has an unconstrained
6444 or task type, don't elaborate it. */
6452 /* If this is a constant related to a return initialized by a reference
6453 to a function call in a function returning by invisible reference:
6455 type Ann is access all Result_Type;
6456 Rnn : constant Ann := Func'reference;
6457 [...]
6458 return Rnn.all;
6460 then elide the temporary by forwarding the return object to Func:
6462 result_type *Rnn = (result_type *) <retval>;
6463 *<retval> = Func (); [return slot optimization]
6464 [...]
6465 return Rnn;
6467 That's necessary if the result type needs finalization because the
6468 temporary would never be adjusted as Expand_Simple_Function_Return
6469 also elides the temporary in this case. */
6474 && current_function_decl
6476 {
6480 gnu_result
6483 gnu_result
6488 }
6492 && (!type_annotate_only
6494 {
6499 /* First deal with erroneous expressions. */
6501 {
6502 /* If this is a named number for which we cannot manipulate
6503 the value, just skip the declaration altogether. */
6508 }
6510 /* Then a special case: we do not want the SLOC of the expression
6511 of the tag to pop up every time it is referenced somewhere. */
6514 }
6515 else
6518 /* If this is a deferred constant with an address clause, we ignore the
6519 full view since the clause is on the partial view and we cannot have
6520 2 different GCC trees for the object. The only bits of the full view
6521 we will use is the initializer, but it will be directly fetched. */
6527 /* If this object has its elaboration delayed, we must force evaluation
6528 of GNU_EXPR now and save it for the freeze point. Note that we need
6529 not do anything special at the global level since the lifetime of the
6530 temporary is fully contained within the elaboration routine. */
6532 {
6534 {
6537 }
6538 }
6539 else
6547 /* Don't do anything if this renaming is handled by the front end and it
6548 does not need debug info. Note that we consider renamings don't need
6549 debug info when optimizing: our way to describe them has a
6550 memory/elaboration footprint.
6552 Don't do anything neither if we are just annotating types and this
6553 object has a composite or task type, don't elaborate it. */
6556 && !optimize
6557 && can_materialize_object_renaming_p
6559 && ! (type_annotate_only
6579 {
6585 /* Materializing renamed subprograms will only benefit the debugging
6586 information as they aren't referenced in the generated code. So
6587 skip them when they aren't needed. Avoid doing this if:
6589 - there is a freeze node: in this case the renamed entity is not
6590 elaborated yet,
6591 - the renamed subprogram is intrinsic: it will not be available in
6592 the debugging information (note that both or only one of the
6593 renaming and the renamed subprograms can be intrinsic). */
6604 }
6612 /* These are fully handled in the front end. */
6613 /* ??? For package renamings, find a way to use GENERIC namespaces so
6614 that we get proper debug information for them. */
6618 /*************************************/
6619 /* Chapter 4: Names and Expressions */
6620 /*************************************/
6623 /* Make sure the designated type is complete before dereferencing. */
6628 /* If atomic access is required on the RHS, build the atomic load. */
6633 /* If storage model access is required on the RHS, build the load. */
6641 {
6644 tree gnu_type;
6648 /* Get the storage model of the array. */
6654 /* Convert vector inputs to their representative array type, to fit
6655 what the code below expects. */
6657 {
6661 }
6663 /* The failure of this assertion will very likely come from a missing
6664 expansion for a packed array access. */
6667 /* First compute the number of dimensions of the array, then
6668 fill the expression array, the order depending on whether
6669 this is a Convention_Fortran array or not. */
6674 ;
6683 else
6689 /* Start with the prefix and build the successive references. */
6695 {
6700 gnu_result
6705 }
6709 /* If atomic access is required on the RHS, build the atomic load. */
6714 /* If storage model access is required on the RHS, build the load. */
6719 }
6723 {
6727 /* Get the storage model of the array. */
6738 /* If this is a slice with non-constant size of an array with constant
6739 size, set the maximum size for the allocation of temporaries. */
6751 /* If storage model access is required on the RHS, build the load. */
6756 }
6760 {
6767 /* gnat_to_gnu_entity does not save the GNU tree made for renamed
6768 discriminants so avoid making recursive calls on each reference
6769 to them by following the appropriate link directly here. */
6771 {
6772 /* For discriminant references in tagged types always substitute
6773 the corresponding discriminant as the actual component. */
6778 /* For discriminant references in untagged types always substitute
6779 the corresponding stored discriminant. */
6782 }
6784 /* Handle extracting the real or imaginary part of a complex.
6785 The real part is the first field and the imaginary the last. */
6790 else
6791 {
6793 tree gnu_offset;
6796 gnu_result
6800 && lvalue_required_for_attribute_p
6803 /* If optimization is enabled and we are inside a loop, we try to
6804 hoist nonconstant but invariant offset computations outside of
6805 the loop, since they very likely contain loads that could turn
6806 out to be hard to move if they end up in active EH regions. */
6814 {
6815 tree invariant
6819 tree factor
6821 /* Divide the offset by its alignment. */
6824 }
6825 }
6829 /* If atomic access is required on the RHS, build the atomic load. */
6834 /* If storage model access is required on the RHS, build the load. */
6839 }
6843 {
6844 /* The attribute designator. */
6847 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6848 is a unit, not an object with a GCC equivalent. */
6850 return
6856 gnat_node);
6859 }
6863 /* Like 'Access as far as we are concerned. */
6871 {
6872 tree gnu_aggr_type;
6874 /* Check that this aggregate has not slipped through the cracks. */
6881 gnu_aggr_type
6885 else
6893 gnu_result
6896 gnu_aggr_type);
6899 gnu_aggr_type);
6901 gnu_result
6902 = build_binary_op
6907 (Next
6909 else
6913 }
6921 else
6931 /* If this is a qualified expression for a tagged type, we mark the type
6932 as used. Because of polymorphism, this might be the only reference to
6933 the tagged type in the program while objects have it as dynamic type.
6934 The debugger needs to see it to display these objects properly. */
6940 gnu_result
6943 kind == N_Type_Conversion
6951 /* Skip further processing if the conversion is deemed a no-op. */
6953 {
6957 }
6959 /* If the result is a pointer type, see if we are improperly
6960 converting to a stricter alignment. */
6963 {
6969 post_error_ne_tree_2
6973 }
6975 /* If we are converting a descriptor to a function pointer, first
6976 build the pointer. */
6988 {
6997 {
7001 }
7003 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
7004 ensure that GNU_OBJ is evaluated only once and perform a full range
7005 test. */
7007 gnu_result
7009 else
7010 {
7019 gnu_result
7021 }
7024 gnu_result
7026 }
7034 ? RDIV_EXPR
7038 /* If the result type is larger than a word, then declare the dependence
7039 on the libgcc routine. */
7066 {
7072 /* Fix operations set up for boolean types in GNU_CODES above. */
7075 {
7087 }
7093 /* If this is a shift, take the count as unsigned since that is what
7094 most machines do and will generate simpler adjustments below. */
7096 {
7097 tree gnu_count_type
7100 gnu_max_shift
7102 /* If the result type is larger than a word, then declare the dependence
7103 on the libgcc routine. */
7106 }
7108 /* If this is a comparison between (potentially) large aggregates, then
7109 declare the dependence on the memcmp routine. */
7116 gnat_node);
7118 /* If this is a modulo/remainder and the result type is larger than a
7119 word, then declare the dependence on the libgcc routine. */
7124 /* Pending generic support for efficient vector logical operations in
7125 GCC, convert vectors to their representative array type view. */
7129 /* If this is a comparison operator, convert any references to an
7130 unconstrained array value into a reference to the actual array. */
7132 {
7138 {
7141 }
7142 }
7144 /* If this is a shift whose count is not guaranteed to be correct,
7145 we need to adjust the shift count. */
7152 gnu_rhs
7156 gnu_max_shift,
7157 build_int_cst
7159 gnu_rhs);
7161 /* For right shifts, the type says what kind of shift to do,
7162 so we may need to choose a different type. In this case,
7163 we have to ignore integer overflow lest it propagates all
7164 the way down and causes a CE to be explicitly raised. */
7166 {
7169 }
7172 {
7175 }
7178 {
7186 }
7188 /* For signed integer addition, subtraction and multiplication, do an
7189 overflow check if required. */
7194 gnu_result
7196 gnat_node);
7197 else
7198 {
7199 /* Some operations, e.g. comparisons of arrays, generate complex
7200 trees that need to be annotated while they are being built. */
7203 }
7205 /* If this is a logical shift with the shift count not verified,
7206 we must return zero if it is too large. We cannot compensate
7207 beforehand in this case. */
7210 gnu_result
7215 gnu_result);
7216 }
7220 {
7223 tree gnu_false
7227 gnu_result
7229 }
7238 /* This case can apply to a boolean or a modular type.
7239 Fall through for a boolean operand since GNU_CODES is set
7240 up to handle this. */
7242 {
7246 gnu_expr);
7248 }
7250 /* ... fall through ... */
7257 /* For signed integer negation and absolute value, do an overflow check
7258 if required. */
7262 gnu_result
7264 gnat_node);
7265 else
7266 gnu_result
7271 {
7277 /* The expression can be either an N_Identifier or an Expanded_Name,
7278 which must represent a type, or a N_Qualified_Expression, which
7279 contains both the type and an initial value for the object. */
7282 {
7286 }
7289 {
7290 const Entity_Id gnat_desig_type
7303 else
7304 {
7308 }
7310 /* See the N_Qualified_Expression case for the rationale. */
7315 }
7316 else
7323 ignore_init_type);
7324 }
7327 /**************************/
7328 /* Chapter 5: Statements */
7329 /**************************/
7337 /* When not optimizing, turn null statements from source into gotos to
7338 the next statement that the middle-end knows how to preserve. */
7340 {
7351 }
7352 else
7357 /* First get the LHS of the statement and convert any reference to an
7358 unconstrained array into a reference to the underlying array. */
7361 /* If the type has a size that overflows, convert this into raise of
7362 Storage_Error: execution shouldn't have gotten here anyway. */
7366 N_Raise_Storage_Error);
7368 /* If the RHS is a function call, let Call_to_gnu do the entire work. */
7370 {
7373 gnu_result
7376 }
7378 /* Otherwise we need to build the assignment statement manually. */
7379 else
7380 {
7382 const Node_Id gnat_inner
7386 const Entity_Id gnat_type
7388 const bool use_memset_p
7393 /* If we use memset, we need to find the innermost expression. */
7395 {
7398 gnat_temp
7403 }
7405 /* Otherwise get the RHS of the statement and do the same processing
7406 as for the LHS above. */
7407 else
7415 /* If an outer atomic access is required on the LHS, build the load-
7416 modify-store sequence. */
7420 /* Or else, if a simple atomic access is required, build the atomic
7421 store. */
7425 /* Or else, if a storage model access is required, build the special
7426 store. */
7429 {
7430 /* We obviously cannot use memset in this case. */
7433 /* We cannot directly move between nonnative storage models. */
7437 gnu_result
7439 }
7441 /* Or else, use memset when the conditions are met. This has already
7442 been validated by Aggr_Assignment_OK_For_Backend in the front-end
7443 and the RHS is thus guaranteed to be of the appropriate form. */
7445 {
7446 tree value
7448 ? integer_zero_node
7452 /* Be extra careful not to write too much data. */
7453 tree size;
7458 else
7462 {
7463 tree mask
7467 }
7470 gnat_node);
7471 }
7473 else
7474 {
7477 /* If a storage model load is present on the RHS, then elide the
7478 temporary associated with it. */
7480 {
7487 }
7489 /* Otherwise build a regular assignment. */
7490 else
7491 gnu_result
7493 }
7495 /* If the assignment type is a regular array and the two sides are
7496 not completely disjoint, play safe and use memmove. But don't do
7497 it for a bit-packed array as it might not be byte-aligned. */
7502 {
7506 tree size
7513 gnat_node);
7514 }
7516 /* If this is an assignment between (potentially) large aggregates,
7517 then declare the dependence on the memcpy routine. */
7523 gnat_node);
7524 }
7528 {
7531 /* Make the outer COND_EXPR. Avoid non-determinism. */
7540 /* Now make a COND_EXPR for each of the "else if" parts. Put each
7541 into the previous "else" part and point to where to put any
7542 outer "else". Also avoid non-determinism. */
7546 {
7556 }
7559 }
7571 /* The only way to enter the block is to fall through to it. */
7573 {
7582 }
7583 else
7588 gnu_result
7598 {
7601 /* If the subprogram is a function, we must return the expression. */
7603 {
7606 /* If this function has copy-in/copy-out parameters parameters and
7607 doesn't return by invisible reference, get the real object for
7608 the return. See Subprogram_Body_to_gnu. */
7612 else
7615 /* Get the GCC tree for the expression to be returned. */
7618 /* Do not remove the padding from GNU_RET_VAL if the inner type is
7619 self-referential since we want to allocate the fixed size. */
7621 && type_is_padding_self_referential
7625 /* If the function returns by direct reference, return a pointer
7626 to the return value, possibly after allocating it. */
7628 {
7630 {
7633 /* And find out whether it is a candidate for Named Return
7634 Value. If so, record it. */
7636 && !optimize_debug
7638 {
7641 /* Strip conversions around the return value. */
7645 /* Strip unpadding around the return value. */
7647 && TYPE_IS_PADDING_P
7651 /* Now apply the test to the return value. */
7653 {
7660 }
7661 }
7663 gnu_ret_val
7665 gnu_ret_val,
7669 gnat_node,
7671 }
7673 else
7674 gnu_ret_val
7676 }
7678 /* Otherwise, if it returns by invisible reference, dereference
7679 the pointer it is passed using the type of the return value
7680 and build the copy operation manually. This ensures that we
7681 don't copy too much data, for example if the return type is
7682 unconstrained with a maximum size. */
7684 {
7685 tree gnu_ret_deref
7687 gnu_ret_obj);
7690 /* Avoid a useless copy with __builtin_return_slot. */
7692 gnu_result
7696 gnu_ret_obj),
7700 }
7701 }
7703 else
7706 /* If we have a return label defined, convert this into a branch to
7707 that label. The return proper will be handled elsewhere. */
7709 {
7713 gnu_ret_val),
7714 gnat_node);
7719 /* When not optimizing, make sure the return is preserved. */
7722 }
7724 /* Otherwise, build a regular return. */
7725 else
7727 }
7736 /***************************/
7737 /* Chapter 6: Subprograms */
7738 /***************************/
7741 /* Unless there is a freeze node, declare the entity. We consider
7742 this a definition even though we're not generating code for the
7743 subprogram because we will be making the corresponding GCC node.
7744 When there is a freeze node, it is considered the definition of
7745 the subprogram and we do nothing until after it is encountered.
7746 That's an efficiency issue: the types involved in the profile
7747 are far more likely to be frozen between the declaration and
7748 the freeze node than before the declaration, so we save some
7749 updates of the GCC node by waiting until the freeze node.
7750 The counterpart is that we assume that there is no reference
7751 to the subprogram between the declaration and the freeze node
7752 in the expanded code; otherwise, it will be interpreted as an
7753 external reference and very likely give rise to a link failure. */
7761 /* This subprogram doesn't exist for code generation purposes, but we
7762 have to elaborate the types of any parameters and result, unless
7763 they are imported types (nothing to generate in this case).
7765 The parameter list may contain types with freeze nodes, e.g. not null
7766 subtypes, so the subprogram itself may carry a freeze node, in which
7767 case its elaboration must be deferred. */
7769 /* Process the parameter types first. */
7772 = First_Formal_With_Extras
7780 /* Then the result type, set to Standard_Void_Type for procedures. */
7781 {
7782 Entity_Id gnat_temp_type
7787 }
7793 /* For a child unit identifier go up a level to get the specification.
7794 We get this when we try to find the spec of a child unit package
7795 that is the compilation unit being compiled. */
7810 /************************/
7811 /* Chapter 7: Packages */
7812 /************************/
7827 /* If this is the body of a generic package - do nothing. */
7829 {
7832 }
7843 /********************************/
7844 /* Chapter 8: Visibility Rules */
7845 /********************************/
7849 /* Nothing to do here - but these may appear in list of declarations. */
7853 /*********************/
7854 /* Chapter 9: Tasks */
7855 /*********************/
7866 /*********************************************************/
7867 /* Chapter 10: Program Structure and Compilation Issues */
7868 /*********************************************************/
7871 /* This is not called for the main unit on which gigi is invoked. */
7883 /* These nodes should only be present when annotating types. */
7893 /* Simply process whatever unit is being inserted. */
7896 else
7897 {
7900 }
7903 /***************************/
7904 /* Chapter 11: Exceptions */
7905 /***************************/
7916 /* Only for reraise in back-end exceptions mode. */
7922 gnu_incoming_exc_ptr),
7923 gnat_node);
7964 /******************************/
7965 /* Chapter 12: Generic Units */
7966 /******************************/
7976 /* These nodes can appear on a declaration list but there is nothing to
7977 to be done with them. */
7981 /**************************************************/
7982 /* Chapter 13: Representation Clauses and */
7983 /* Implementation-Dependent Features */
7984 /**************************************************/
7989 /* The only one we need to deal with is 'Address since, for the others,
7990 the front-end puts the information elsewhere. */
7994 /* And we only deal with 'Address if the object has a Freeze node. */
7997 {
8000 /* Get the value to use as the address and save it as the equivalent
8001 for the object; when it is frozen, gnat_to_gnu_entity will do the
8002 right thing. For a subprogram, put the naked address but build a
8003 meaningfull expression for an object in case its address is taken
8004 before the Freeze node is encountered; this can happen if the type
8005 of the object is limited and it is initialized with the result of
8006 a function call. */
8009 else
8010 {
8012 /* Drop atomic and volatile qualifiers for the expression. */
8014 gnu_type
8017 gnu_temp
8019 }
8022 }
8028 /* We do nothing with these. SEM puts the information elsewhere. */
8034 {
8044 /* First retrieve the 3 operand lists built by the front-end. */
8047 {
8054 }
8058 {
8065 }
8069 gnu_clobbers
8072 gnu_clobbers);
8074 /* Then perform some standard checking and processing on the
8075 operands. In particular, mark them addressable if needed. */
8083 {
8085 constraint
8091 {
8092 /* If the operand is going to end up in memory,
8093 mark it addressable. Note that we don't test
8094 allows_mem like in the input case below; this
8095 is modeled on the C front-end. */
8097 {
8104 }
8105 }
8106 else
8110 }
8113 {
8115 constraint
8121 {
8122 /* If the operand is going to end up in memory,
8123 mark it addressable. */
8125 {
8132 }
8133 }
8134 else
8138 }
8144 }
8145 else
8150 /****************/
8151 /* Added Nodes */
8152 /****************/
8154 /* Markers are created by the ABE mechanism to capture information which
8155 is either unavailable of expensive to recompute. Markers do not have
8156 and runtime semantics, and should be ignored. */
8164 /* This construct doesn't define a scope so we don't push a binding
8165 level around the statement list, but we wrap it in a SAVE_EXPR to
8166 protect it from unsharing. Elaborate the expression as part of the
8167 same statement group as the actions so that the type declaration
8168 gets inserted there as well. This ensures that the type elaboration
8169 code is issued past the actions computing values on which it might
8170 depend. */
8179 gnu_result
8205 {
8206 const Entity_Id gnat_desig_type
8209 const bool pool_is_storage_model
8215 /* Make sure the designated type is complete before dereferencing,
8216 in case it is a Taft Amendment type. */
8222 /* If this is a thin pointer, we must first dereference it to create
8223 a fat pointer, then go back below to a thin pointer. The reason
8224 for this is that we need to have a fat pointer someplace in order
8225 to properly compute the size. */
8229 gnu_ptr));
8231 /* If this is a fat pointer, the object must have been allocated with
8232 the template in front of the array. So pass the template address,
8233 and get the total size; do it by converting to a thin pointer. */
8235 gnu_ptr
8237 (TYPE_OBJECT_RECORD_TYPE
8239 gnu_ptr);
8243 /* If this is a thin pointer, the object must have been allocated with
8244 the template in front of the array. So pass the template address,
8245 and get the total size. */
8247 gnu_ptr
8249 gnu_ptr,
8251 byte_position
8252 (DECL_CHAIN
8255 /* If we have a special dynamic constrained subtype on the node, use
8256 it to compute the size; otherwise, use the designated subtype. */
8258 {
8259 gnu_actual_obj_type
8263 gnu_actual_obj_type
8265 gnu_actual_obj_type,
8268 }
8269 else
8277 gnu_result
8281 }
8289 else
8294 /* The only validation we currently do on an unchecked conversion is
8295 that of aliasing assumptions. */
8305 /* These nodes should only be present when annotating types. */
8311 /* Other nodes are not supposed to reach here. */
8313 }
8315 /* If we are in the elaboration procedure, check if we are violating the
8316 No_Elaboration_Code restriction by having a non-empty statement. */
8323 /* If we pushed the processing of the elaboration routine, pop it back. */
8327 /* When not optimizing, turn boolean rvalues B into B != false tests
8328 so that we can put the location information of the reference to B on
8329 the inequality operator for better debug info. */
8343 {
8344 gnu_result
8350 }
8352 /* Set the location information on the result if it's not a simple name
8353 or something that contains a simple name, for example a tag, because
8354 we don"t want all the references to get the location of the first use.
8355 Note that we may have no result if we tried to build a CALL_EXPR node
8356 to a procedure with no side-effects and optimization is enabled. */
8360 && gnu_result
8364 /* If we're supposed to return something of void_type, it means we have
8365 something we're elaborating for effect, so just return. */
8369 /* If the result is a constant that overflowed, raise Constraint_Error. */
8371 {
8373 gnu_result
8376 N_Raise_Constraint_Error));
8377 }
8379 /* If the result has side-effects and is of an unconstrained type, protect
8380 the expression in case it will be referenced multiple times, i.e. for
8381 its value and to compute the size of an object. But do it neither for
8382 an object nor a renaming declaration, nor a return statement of a call
8383 to a function that returns an unconstrained record type with default
8384 discriminant, because there is no size to be computed in these cases
8385 and this will create a useless temporary. We must do this before any
8386 conversions. */
8397 /* Now convert the result to the result type, unless we are in one of the
8398 following cases:
8400 1. If this is the LHS of an assignment or an actual parameter of a
8401 call, return the result almost unmodified since the RHS will have
8402 to be converted to our type in that case, unless the result type
8403 has a simpler size or for array types because this size might be
8404 changed in-between. Likewise if there is just a no-op unchecked
8405 conversion in-between. Similarly, don't convert integral types
8406 that are the operands of an unchecked conversion since we need
8407 to ignore those conversions (for 'Valid).
8409 2. If we have a label (which doesn't have any well-defined type), a
8410 field or an error, return the result almost unmodified. Similarly,
8411 if the two types are record types with the same name, don't convert.
8412 This will be the case when we are converting from a packable version
8413 of a type to its original type and we need those conversions to be
8414 NOPs in order for assignments into these types to work properly.
8416 3. If the type is void or if we have no result, return error_mark_node
8417 to show we have no result.
8419 4. If this is a call to a function that returns with variable size and
8420 the call is used as the expression in either an object or a renaming
8421 declaration, return the result unmodified because we want to use the
8422 return slot optimization in this case.
8424 5. If this is a reference to an unconstrained array which is used either
8425 as the prefix of an attribute reference that requires an lvalue or in
8426 a return statement, then return the result unmodified because we want
8427 to return the original bounds.
8429 6. Finally, if the type of the result is already correct. */
8447 && (CONTAINS_PLACEHOLDER_P
8453 {
8454 /* Remove padding only if the inner object is of self-referential
8455 size: in that case it must be an object of unconstrained type
8456 with a default discriminant and we want to avoid copying too
8457 much data. But do not remove it if it is already too small. */
8464 gnu_result);
8465 }
8474 {
8475 /* Remove any padding. */
8477 }
8487 ;
8494 ;
8499 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
8506 }
8508 /* Similar to gnat_to_gnu, but discard any object that might be created in
8509 the course of the translation of GNAT_NODE, which must be an "external"
8510 expression in the sense that it will be elaborated elsewhere. */
8512 tree
8514 {
8518 /* Force the local context and create a fake scope that we zap
8519 at the end so declarations will not be stuck either in the
8520 global varpool or in the current scope. */
8522 {
8525 }
8526 else
8538 /* Do not import locations from external units. */
8543 }
8545 /* Return true if the statement list STMT_LIST is empty. */
8547 static bool
8549 {
8550 tree_stmt_iterator tsi;
8553 {
8556 /* Anything else than an empty STMT_STMT counts as something. */
8559 }
8562 }
8564 /* Record the current code position in GNAT_NODE. */
8566 static void
8568 {
8573 }
8575 /* Insert the code for GNAT_NODE at the position saved for that node. */
8577 static void
8579 {
8582 /* It's too late to remove the STMT_STMT itself at this point. */
8587 }
8589 /* Start a new statement group chained to the previous group. */
8591 void
8593 {
8596 /* First see if we can get one from the free list. */
8599 else
8605 }
8607 /* Add GNU_STMT to the current statement group. If it is an expression with
8608 no effects, it is ignored. */
8610 void
8612 {
8614 }
8616 /* Similar, but the statement is always added, regardless of side-effects. */
8618 void
8620 {
8622 }
8624 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
8626 void
8628 {
8632 }
8634 /* Similar, but the statement is always added, regardless of side-effects. */
8636 void
8638 {
8642 }
8644 /* Add a declaration statement for GNU_DECL to the current statement group.
8645 Get the SLOC to be put onto the statement from GNAT_NODE. */
8647 void
8649 {
8653 /* If this is a variable that Gigi is to ignore, we may have been given
8654 an ERROR_MARK. So test for it. We also might have been given a
8655 reference for a renaming. So only do something for a decl. Also
8656 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
8664 /* If we are external or global, we don't want to output the DECL_EXPR for
8665 this DECL node since we already have evaluated the expressions in the
8666 sizes and positions as globals and doing it again would be wrong. */
8668 {
8669 /* Mark everything as used to prevent node sharing with subprograms.
8670 Note that walk_tree knows how to deal with TYPE_DECL, but neither
8671 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
8675 {
8679 }
8680 }
8681 else
8684 /* Mark our TYPE_ADA_SIZE field now since it will not be gimplified. */
8691 {
8692 /* If this is a variable and an initializer is attached to it, it must be
8693 valid for the context. Similar to init_const in create_var_decl. */
8698 {
8701 {
8704 }
8706 /* Remove any padding so the assignment is done properly. */
8709 gnu_stmt
8712 }
8714 /* If this is the initialization of a (potentially) large aggregate, then
8715 declare the dependence on the memcpy routine. */
8720 gnat_node);
8721 }
8722 }
8724 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
8726 static tree
8728 {
8734 /* Don't mark a dummy type as visited because we want to mark its sizes
8735 and fields once it's filled in. */
8739 /* The test in gimplify_type_sizes is on the main variant. */
8744 }
8746 /* Mark nodes rooted at T with TREE_VISITED and types as having their
8747 sized gimplified. We use this to indicate all variable sizes and
8748 positions in global types may not be shared by any subprogram. */
8750 void
8752 {
8754 }
8756 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
8757 set its location to that of GNAT_NODE if present, but with column info
8758 cleared so that conditional branches generated as part of the cleanup
8759 code do not interfere with coverage analysis tools. */
8761 static void
8763 {
8767 /* An EH_ELSE_EXPR must be by itself, and that's all we need when we
8768 use it. The assert below makes sure that is so. Should we ever
8769 need more than that, we could combine EH_ELSE_EXPRs, and copy
8770 non-EH_ELSE_EXPR stmts into both cleanup paths of an
8771 EH_ELSE_EXPR. */
8773 {
8776 }
8777 else
8778 {
8783 }
8784 }
8786 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
8788 void
8790 {
8793 }
8795 /* Return code corresponding to the current code group. It is normally
8796 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
8797 BLOCK or cleanups were set. */
8799 tree
8801 {
8805 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
8806 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
8807 make a BIND_EXPR. Note that we nest in that because the cleanup may
8808 reference variables in the block. */
8820 /* Remove this group from the stack and add it to the free list. */
8826 }
8828 /* Return whether the current statement group may fall through. */
8832 {
8835 else
8837 }
8839 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
8840 statements.*/
8842 static void
8844 {
8845 Node_Id gnat_node;
8851 }
8853 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
8854 If BINDING_P is true, push and pop a binding level around the list. */
8856 static tree
8858 {
8870 }
8872 /* Generate GIMPLE in place for the expression at *EXPR_P. */
8874 int
8877 {
8880 tree op;
8886 {
8890 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
8891 is put into static memory. We know that it's going to be read-only
8892 given the semantics we have and it must be in static memory when the
8893 reference is in an elaboration procedure. */
8895 {
8899 }
8901 /* Replace atomic loads with their first argument. That's necessary
8902 because the gimplifier would create a temporary otherwise. */
8905 {
8908 {
8914 else
8916 }
8917 else
8919 }
8923 /* If we are passing a constant fat pointer CONSTRUCTOR, make sure it is
8924 put into static memory; this performs a restricted version of constant
8925 propagation on fat pointers in calls. But do not do it for strings to
8926 avoid blocking concatenation in the caller when it is inlined. */
8928 {
8934 {
8942 }
8943 }
8949 /* The expressions for the RM bounds must be gimplified to ensure that
8950 they are properly elaborated. See gimplify_decl_expr. */
8955 {
8960 {
8964 }
8968 {
8972 }
8973 }
8977 /* If this is an aggregate type, build a null pointer of the appropriate
8978 type and dereference it. */
8983 integer_zero_node));
8985 /* Otherwise, just make a VAR_DECL. */
8986 else
8987 {
8990 }
8998 /* Propagate TREE_NO_WARNING from expression to temporary by using the
8999 SAVE_EXPR itself as an intermediate step. See gimplify_save_expr. */
9001 ;
9004 else
9009 {
9022 }
9027 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
9028 type to a scalar one, explicitly create the local temporary. That's
9029 required if the type is passed by reference. */
9033 {
9042 }
9046 /* We should only do this if we are just elaborating for side effects,
9047 but we can't know that yet. */
9053 }
9056 }
9058 /* Generate GIMPLE in place for the statement at *STMT_P. */
9060 static enum gimplify_status
9062 {
9066 {
9072 {
9078 /* Build the condition expression from the test, if any. */
9080 {
9081 /* Deal with the optimization hints. */
9085 annot_expr_ivdep_kind),
9086 integer_zero_node);
9090 annot_expr_unroll_kind),
9091 integer_one_node);
9095 annot_expr_unroll_kind),
9100 annot_expr_no_vector_kind),
9101 integer_zero_node);
9105 annot_expr_vector_kind),
9106 integer_zero_node);
9108 gnu_cond
9111 }
9113 /* Set to emit the statements of the loop. */
9116 /* We first emit the start label and then a conditional jump to the
9117 end label if there's a top condition, then the update if it's at
9118 the top, then the body of the loop, then a conditional jump to
9119 the end label if there's a bottom condition, then the update if
9120 it's at the bottom, and finally a jump to the start label and the
9121 definition of the end label. */
9123 gnu_start_label),
9124 stmt_p);
9145 gnu_end_label),
9146 stmt_p);
9148 }
9151 /* Build a statement to jump to the corresponding end label, then
9152 see if it needs to be conditional. */
9161 }
9162 }
9164 /* Force a reference to each of the entities in GNAT_PACKAGE recursively.
9166 This routine is exclusively called in type_annotate mode, to compute DDA
9167 information for types in withed units, for ASIS use. */
9169 static void
9171 {
9172 Entity_Id gnat_entity;
9177 {
9180 /* We are interested only in entities visible from the main unit. */
9184 /* Skip stuff internal to the compiler. */
9196 /* Skip named numbers. */
9200 /* Skip generic declarations. */
9204 /* Skip formal objects. */
9208 /* Skip package bodies. */
9212 /* Skip limited views that point back to the main unit. */
9218 /* Skip types that aren't frozen. */
9222 /* Recurse on real packages that aren't in the main unit. */
9224 {
9228 }
9229 else
9231 }
9232 }
9234 /* Force a reference to each of the entities in packages withed by GNAT_NODE.
9235 Operate recursively but check that we aren't elaborating something more
9236 than once.
9238 This routine is exclusively called in type_annotate mode, to compute DDA
9239 information for types in withed units, for ASIS use. */
9241 static void
9243 {
9244 Entity_Id gnat_with_clause;
9246 /* Process each unit only once. As we trace the context of all relevant
9247 units transitively, including generic bodies, we may encounter the
9248 same generic unit repeatedly. */
9252 /* Save entities in all context units. A body may have an implicit_with
9253 on its own spec, if the context includes a child unit, so don't save
9254 the spec twice. */
9261 {
9272 {
9275 /* Retrieve compilation unit node of generic body. */
9280 /* If body is available, elaborate its context. */
9283 }
9284 }
9288 }
9290 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
9292 static void
9294 {
9299 /* If this is a package, generate code for the package body, if any. */
9301 {
9306 }
9308 /* Don't do anything for class-wide types as they are always transformed
9309 into their root type. */
9313 /* Likewise for the entities internally used by the front-end to register
9314 primitives covering abstract interfaces, see Expand_N_Freeze_Entity. */
9318 /* Check for an old definition if this isn't an object with address clause,
9319 since the saved GCC tree is the address expression in that case. */
9320 gnu_old
9324 /* Don't do anything for subprograms that may have been elaborated before
9325 their freeze nodes. This can happen, for example, because of an inner
9326 call in an instance body or because of previous compilation of a spec
9327 for inlining purposes. */
9335 /* If we have a non-dummy type old tree, we have nothing to do, except for
9336 aborting, since this node was never delayed as it should have been. We
9337 let this happen for concurrent types and their Corresponding_Record_Type,
9338 however, because each might legitimately be elaborated before its own
9339 freeze node, e.g. while processing the other. */
9343 {
9348 }
9350 /* Reset the saved tree, if any, and elaborate the object or type for real.
9351 If there is a full view, elaborate it and use the result. And, if this
9352 is the root type of a class-wide type, reuse it for the latter. */
9354 {
9359 {
9366 {
9369 }
9370 }
9376 }
9380 {
9389 /* Propagate back-annotations from full view to partial view. */
9399 /* The above call may have defined this entity (the simplest example
9400 of this is when we have a private enumeral type since the bounds
9401 will have the public view). */
9404 }
9405 else
9406 {
9407 tree gnu_init
9413 }
9420 /* If we have an old type and we've made pointers to this type, update those
9421 pointers. If this is a Taft amendment type in the main unit, we need to
9422 mark the type as used since other units referencing it don't see the full
9423 declaration and, therefore, cannot mark it as used themselves. */
9425 {
9432 }
9433 }
9435 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
9436 We make two passes, one to elaborate anything other than bodies (but
9437 we declare a function if there was no spec). The second pass
9438 elaborates the bodies.
9440 We make a complete pass through both lists if PASS1P is true, then make
9441 the second pass over both lists if PASS2P is true. The lists usually
9442 correspond to the public and private parts of a package. */
9444 static void
9447 {
9449 Node_Id gnat_decl;
9460 {
9461 /* For package specs, we recurse inside the declarations,
9462 thus taking the two pass approach inside the boundary. */
9470 /* Similarly for any declarations in the actions of a
9471 freeze node. */
9473 {
9476 }
9478 /* Package bodies with freeze nodes get their elaboration deferred
9479 until the freeze node, but the code must be placed in the right
9480 place, so record the code position now. */
9488 (Corresponding_Spec
9491 record_code_position
9494 /* We defer most subprogram bodies to the second pass. For bodies
9495 that act as their own specs and stubs, the entity itself must be
9496 elaborated in the first pass, because it may be used in other
9497 declarations. */
9499 {
9501 {
9506 }
9507 }
9510 {
9511 Entity_Id gnat_subprog
9517 }
9519 /* Concurrent stubs stand for the corresponding subprogram bodies,
9520 which are deferred like other bodies. */
9523 ;
9525 /* Renamed subprograms may not be elaborated yet at this point
9526 since renamings do not trigger freezing. Wait for the second
9527 pass to take care of them. */
9529 ;
9531 else
9533 }
9535 /* Here we elaborate everything we deferred above except for package bodies,
9536 which are elaborated at their freeze nodes. Note that we must also
9537 go inside things (package specs and freeze nodes) the first pass did. */
9544 {
9563 }
9564 }
9566 /* Make a unary operation of kind CODE using build_unary_op, but guard
9567 the operation by an overflow check. CODE can be one of NEGATE_EXPR
9568 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
9569 the operation is to be performed in that type. GNAT_NODE is the gnat
9570 node conveying the source location for which the error should be
9571 signaled. */
9573 static tree
9575 Node_Id gnat_node)
9576 {
9585 }
9587 /* Make a binary operation of kind CODE using build_binary_op, but guard
9588 the operation by an overflow check. CODE can be one of PLUS_EXPR,
9589 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
9590 Usually the operation is to be performed in that type. GNAT_NODE is
9591 the GNAT node conveying the source location for which the error should
9592 be signaled. */
9594 static tree
9597 {
9606 /* Assert that the precision is a power of 2. */
9609 /* Prefer a constant on the RHS to simplify checks. */
9613 {
9617 }
9621 /* If we can fold the expression to a constant, just return it.
9622 The caller will deal with overflow, no need to generate a check. */
9626 /* If no operand is a constant, we use the generic implementation. */
9628 {
9629 /* First convert the operands to the result type like build_binary_op.
9630 This is where the bias is made explicit for biased types. */
9634 /* Never inline a 64-bit mult for a 32-bit target, it's way too long. */
9636 {
9642 }
9644 /* Likewise for a 128-bit mult and a 64-bit target. */
9646 {
9652 }
9657 {
9669 }
9672 tree call
9680 return
9682 }
9684 /* If one operand is a constant, we expose the overflow condition to enable
9685 a subsequent simplication or even elimination. */
9687 {
9691 /* When rhs > 0, overflow when lhs > type_max - rhs. */
9696 /* When rhs < 0, overflow when lhs < type_min - rhs. */
9700 else
9706 {
9709 /* When lhs > 0, overflow when rhs < lhs - type_max. */
9714 /* When lhs < 0, overflow when rhs > lhs - type_min. */
9718 else
9720 }
9721 else
9722 {
9725 /* When rhs > 0, overflow when lhs < type_min + rhs. */
9730 /* When rhs < 0, overflow when lhs > type_max + rhs. */
9734 else
9736 }
9742 {
9749 /* When rhs > 1, overflow outside [type_min/rhs; type_max/rhs]. */
9750 check
9756 }
9758 {
9763 /* When rhs == -1, overflow if lhs == type_min. */
9764 check
9766 else
9767 /* When rhs < -1, overflow outside [type_max/rhs; type_min/rhs]. */
9768 check
9774 }
9775 else
9781 }
9784 }
9786 /* GNU_COND contains the condition corresponding to an index, overflow or
9787 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR
9788 if GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
9789 REASON is the code that says why the exception is raised. GNAT_NODE is
9790 the node conveying the source location for which the error should be
9791 signaled.
9793 We used to propagate TREE_SIDE_EFFECTS from GNU_EXPR to the COND_EXPR,
9794 overwriting the setting inherited from the call statement, on the ground
9795 that the expression need not be evaluated just for the check. However
9796 that's incorrect because, in the GCC type system, its value is presumed
9797 to be valid so its comparison against the type bounds always yields true
9798 and, therefore, could be done without evaluating it; given that it can
9799 be a computation that overflows the bounds, the language may require the
9800 check to fail and thus the expression to be evaluated in this case. */
9802 static tree
9804 {
9805 tree gnu_call
9807 return
9813 gnu_expr);
9814 }
9816 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
9817 checks if OVERFLOW_P is true. If TRUNCATE_P is true, do a fp-to-integer
9818 conversion with truncation, otherwise round. GNAT_NODE is the GNAT node
9819 conveying the source location for which the error should be signaled. */
9821 static tree
9824 {
9831 /* If we are not doing any checks, the output is an integral type and the
9832 input is not a floating-point type, just do the conversion. This is
9833 required for packed array types and is simpler in all cases anyway. */
9839 /* If the mode of the input base type is larger, then converting to it below
9840 may pessimize the final conversion step, for example generate a libcall
9841 instead of a simple instruction, so use a narrower type in this case. */
9848 /* First convert the expression to the base type. This will never generate
9849 code, but makes the tests below simpler. But don't do this if converting
9850 from an integer type to an unconstrained array type since then we need to
9851 get the bounds from the original (unpacked) type. */
9855 /* If overflow checks are requested, we need to be sure the result will fit
9856 in the output base type. But don't do this if the input is integer and
9857 the output floating-point. */
9860 {
9861 /* Ensure GNU_EXPR only gets evaluated once. */
9867 tree gnu_out_ub
9875 /* Convert the lower bounds to signed types, so we're sure we're
9876 comparing them properly. Likewise, convert the upper bounds
9877 to unsigned types. */
9880 gnu_in_lb
9885 gnu_in_ub
9889 gnu_out_lb
9893 gnu_out_ub
9896 /* Check each bound separately and only if the result bound
9897 is tighter than the bound on the input type. Note that all the
9898 types are base types, so the bounds must be constant. Also,
9899 the comparison is done in the base type of the input, which
9900 always has the proper signedness. First check for input
9901 integer (which means output integer), output float (which means
9902 both float), or mixed, in which case we always compare.
9903 Note that we have to do the comparison which would *fail* in the
9904 case of an error since if it's an FP comparison and one of the
9905 values is a NaN or Inf, the comparison will fail. */
9912 gnu_cond
9913 = invert_truthvalue
9916 gnu_out_lb)));
9924 gnu_cond
9926 invert_truthvalue
9928 gnu_input,
9930 gnu_out_ub))));
9935 }
9937 /* Now convert to the result base type. If this is a non-truncating
9938 float-to-integer conversion, round. */
9942 {
9948 /* The following calculations depend on proper rounding to even
9949 of each arithmetic operation. In order to prevent excess
9950 precision from spoiling this property, use the widest hardware
9951 floating-point type if FP_ARITH_MAY_WIDEN is true. */
9952 calc_type
9955 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
9962 /* If the input is strictly negative, subtract this value
9963 and otherwise add it from the input. For 0.5, the result
9964 is exactly between 1.0 and the machine number preceding 1.0
9965 (for calc_type). Since the last bit of 1.0 is even, this 0.5
9966 will round to 1.0, while all other number with an absolute
9967 value less than 0.5 round to 0.0. For larger numbers exactly
9968 halfway between integers, rounding will always be correct as
9969 the true mathematical result will be closer to the higher
9970 integer compared to the lower one. So, this constant works
9971 for all floating-point numbers.
9973 The reason to use the same constant with subtract/add instead
9974 of a positive and negative constant is to allow the comparison
9975 to be scheduled in parallel with retrieval of the constant and
9976 conversion of the input to the calc_type (if necessary). */
9981 gnu_comp
9983 gnu_add_pred_half
9985 gnu_subtract_pred_half
9989 }
9995 else
9998 /* If this is a conversion between an integer type larger than a word and a
9999 floating-point type, then declare the dependence on the libgcc routine. */
10009 }
10011 /* Return true if GNU_EXPR can be directly addressed. This is the case
10012 unless it is an expression involving computation or if it involves a
10013 reference to a bitfield or to an object not sufficiently aligned for
10014 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
10015 be directly addressed as an object of this type.
10017 *** Notes on addressability issues in the Ada compiler ***
10019 This predicate is necessary in order to bridge the gap between Gigi
10020 and the middle-end about addressability of GENERIC trees. A tree
10021 is said to be addressable if it can be directly addressed, i.e. if
10022 its address can be taken, is a multiple of the type's alignment on
10023 strict-alignment architectures and returns the first storage unit
10024 assigned to the object represented by the tree.
10026 In the C family of languages, everything is in practice addressable
10027 at the language level, except for bit-fields. This means that these
10028 compilers will take the address of any tree that doesn't represent
10029 a bit-field reference and expect the result to be the first storage
10030 unit assigned to the object. Even in cases where this will result
10031 in unaligned accesses at run time, nothing is supposed to be done
10032 and the program is considered as erroneous instead (see PR c/18287).
10034 The implicit assumptions made in the middle-end are in keeping with
10035 the C viewpoint described above:
10036 - the address of a bit-field reference is supposed to be never
10037 taken; the compiler (generally) will stop on such a construct,
10038 - any other tree is addressable if it is formally addressable,
10039 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
10041 In Ada, the viewpoint is the opposite one: nothing is addressable
10042 at the language level unless explicitly declared so. This means
10043 that the compiler will both make sure that the trees representing
10044 references to addressable ("aliased" in Ada parlance) objects are
10045 addressable and make no real attempts at ensuring that the trees
10046 representing references to non-addressable objects are addressable.
10048 In the first case, Ada is effectively equivalent to C and handing
10049 down the direct result of applying ADDR_EXPR to these trees to the
10050 middle-end works flawlessly. In the second case, Ada cannot afford
10051 to consider the program as erroneous if the address of trees that
10052 are not addressable is requested for technical reasons, unlike C;
10053 as a consequence, the Ada compiler must arrange for either making
10054 sure that this address is not requested in the middle-end or for
10055 compensating by inserting temporaries if it is requested in Gigi.
10057 The first goal can be achieved because the middle-end should not
10058 request the address of non-addressable trees on its own; the only
10059 exception is for the invocation of low-level block operations like
10060 memcpy, for which the addressability requirements are lower since
10061 the type's alignment can be disregarded. In practice, this means
10062 that Gigi must make sure that such operations cannot be applied to
10063 non-BLKmode bit-fields.
10065 The second goal is achieved by means of the addressable_p predicate,
10066 which computes whether a temporary must be inserted by Gigi when the
10067 address of a tree is requested; if so, the address of the temporary
10068 will be used in lieu of that of the original tree and some glue code
10069 generated to connect everything together. */
10071 static bool
10073 {
10074 /* For an integral type, the size of the actual type of the object may not
10075 be greater than that of the expected type, otherwise an indirect access
10076 in the latter type wouldn't correctly set all the bits of the object. */
10082 /* The size of the actual type of the object may not be smaller than that
10083 of the expected type, otherwise an indirect access in the latter type
10084 would be larger than the object. But only record types need to be
10085 considered in practice for this case. */
10092 {
10097 /* All DECLs are addressable: if they are in a register, we can force
10098 them to memory. */
10103 /* Taking the address of a dereference yields the original pointer. */
10109 /* Taking the address yields a pointer to the constant pool. */
10113 /* Taking the address of a static constructor yields a pointer to the
10114 tree constant pool. */
10127 /* All rvalues are deemed addressable since taking their address will
10128 force a temporary to be created by the middle-end. */
10132 /* The address of a compound expression is that of its 2nd operand. */
10136 /* We accept &COND_EXPR as soon as both operands are addressable and
10137 expect the outcome to be the address of the selected operand. */
10143 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
10144 the field is sufficiently aligned, in case it is subject
10145 to a pragma Component_Alignment. But we don't need to
10146 check the alignment of the containing record, as it is
10147 guaranteed to be not smaller than that of its most
10148 aligned field that is not a bit-field. */
10149 && (!STRICT_ALIGNMENT
10152 /* The field of a padding record is always addressable. */
10166 {
10167 /* This is addressable if we can avoid a copy. */
10171 && (!STRICT_ALIGNMENT
10176 && (!STRICT_ALIGNMENT
10182 }
10186 }
10187 }
10189 /* Do the processing for the declaration of a GNAT_ENTITY, a type or subtype.
10190 If a Freeze node exists for the entity, delay the bulk of the processing.
10191 Otherwise make a GCC type for GNAT_ENTITY and set up the correspondence. */
10193 void
10195 {
10196 tree gnu_old
10199 /* If we are to delay elaboration of this type, just do any elaboration
10200 needed for expressions within the declaration and make a dummy node
10201 for it and its Full_View (if any), in case something points to it.
10202 Do not do this if it has already been done (the only way that can
10203 happen is if the private completion is also delayed). */
10205 {
10209 {
10214 {
10218 }
10219 }
10222 }
10224 /* If we saved away a dummy type for this node, it means that this made the
10225 type that corresponds to the full type of an incomplete type. Clear that
10226 type for now and then update the type in the pointers below. But, if the
10227 saved type is not dummy, it very likely means that we have a use before
10228 declaration for the type in the tree, what we really cannot handle. */
10230 {
10235 }
10237 /* Now fully elaborate the type. */
10241 /* If we have an old type and we've made pointers to this type, update those
10242 pointers. If this is a Taft amendment type in the main unit, we need to
10243 mark the type as used since other units referencing it don't see the full
10244 declaration and, therefore, cannot mark it as used themselves. */
10246 {
10251 }
10253 /* If this is a record type corresponding to a task or protected type
10254 that is a completion of an incomplete type, perform a similar update
10255 on the type. ??? Including protected types here is a guess. */
10259 {
10260 tree gnu_task_old
10270 }
10271 }
10273 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
10274 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
10275 associations that are from RECORD_TYPE. If we see an internal record, make
10276 a recursive call to fill it in as well. */
10278 static tree
10280 {
10282 tree field;
10285 {
10288 /* _Parent is an internal field, but may have values in the aggregate,
10289 so check for values first. */
10291 {
10294 }
10297 {
10302 }
10303 else
10304 /* If we have a record subtype, the names will match, but not the
10305 actual FIELD_DECLs. */
10308 {
10311 }
10317 }
10320 }
10322 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
10323 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
10324 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
10326 static tree
10328 {
10331 /* We test for GNU_FIELD being empty in the case where a variant
10332 was the last thing since we don't take things off GNAT_ASSOC in
10333 that case. We check GNAT_ASSOC in case we have a variant, but it
10334 has no fields. */
10337 {
10343 /* The expander is supposed to put a single component selector name
10344 in every record component association. */
10347 /* Ignore discriminants that have Corresponding_Discriminants in tagged
10348 types since we'll be setting those fields in the parent subtype. */
10354 /* Also ignore discriminants of Unchecked_Unions. */
10361 /* Convert to the type of the field. */
10364 /* Add the field and expression to the list. */
10366 }
10371 {
10372 /* Verify that every entry in GNU_LIST was used. */
10375 }
10378 }
10380 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
10381 the first element of an array aggregate. It may itself be an aggregate.
10382 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate. */
10384 static tree
10386 {
10391 {
10392 tree gnu_expr;
10394 /* If the expression is itself an array aggregate then first build the
10395 innermost constructor if it is part of our array (multi-dimensional
10396 case). */
10402 else
10403 {
10404 /* If the expression is a conversion to an unconstrained array type,
10405 skip it to avoid spilling to memory. */
10410 else
10414 }
10421 integer_one_node));
10422 }
10425 }
10427 /* Process a N_Validate_Unchecked_Conversion node. */
10429 static void
10431 {
10435 /* If the target is a pointer type, see if we are either converting from a
10436 non-pointer or from a pointer to a type with a different alias set and
10437 warn if so, unless the pointer has been marked to alias everything. */
10440 {
10450 target_alias_set)))
10451 {
10455 gnat_node);
10458 }
10459 }
10461 /* Likewise if the target is a fat pointer type, but we have no mechanism to
10462 mitigate the problem in this case, so we unconditionally warn. */
10464 {
10465 tree gnu_source_desig_type
10469 tree gnu_target_desig_type
10476 target_alias_set)))
10477 {
10481 gnat_node);
10482 }
10483 }
10484 }
10486 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a
10487 source code location and false if it doesn't. If CLEAR_COLUMN is
10488 true, set the column information to 0. If DECL is given and SLOC
10489 refers to a File with an instance, map DECL to that instance. */
10491 bool
10493 const_tree decl)
10494 {
10499 {
10502 }
10509 /* We can have zero if pragma Source_Reference is in effect. */
10513 /* Translate the location. */
10514 *locus
10521 }
10523 /* Return whether GNAT_NODE is a defining identifier for a renaming that comes
10524 from the parameter association for the instantiation of a generic. We do
10525 not want to emit source location for them: the code generated for their
10526 initialization is likely to disturb debugging. */
10528 bool
10530 {
10537 /* Get the object declaration of the renamed object, if any and if the
10538 renamed object is a mere identifier. */
10547 }
10549 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
10550 don't do anything if it doesn't correspond to a source location. And,
10551 if CLEAR_COLUMN is true, set the column information to 0. */
10553 static void
10555 {
10556 location_t locus;
10558 /* Do not set a location for constructs likely to disturb debugging. */
10560 {
10566 }
10572 }
10574 /* More elaborate version of set_expr_location_from_node to be used in more
10575 general contexts, for example the result of the translation of a generic
10576 GNAT node. */
10578 static void
10580 {
10581 /* Set the location information on the node if it is a real expression.
10582 References can be reused for multiple GNAT nodes and they would get
10583 the location information of their last use. Also make sure not to
10584 overwrite an existing location as it is probably more precise. */
10587 {
10588 CASE_CONVERT:
10597 /* ... fall through ... */
10601 {
10604 }
10606 }
10607 }
10609 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
10610 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
10611 most sense. Return true if a sensible assignment was performed. */
10613 static bool
10615 {
10616 Node_Id gnat_end_label;
10617 location_t end_locus;
10619 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
10620 end_locus when there is one. We consider only GNAT nodes with a possible
10621 End_Label attached. If the End_Label actually was unassigned, fallback
10622 on the original node. We'd better assign an explicit sloc associated with
10623 the outer construct in any case. */
10626 {
10632 else
10643 }
10648 /* Some expanded subprograms have neither an End_Label nor a Sloc
10649 attached. Notify that to callers. For a block statement with no
10650 End_Label, clear column information, so that the tree for a
10651 transient block does not receive the sloc of a source condition. */
10658 {
10669 }
10670 }
10672 /* Post an error message. MSG is the error message, properly annotated.
10673 NODE is the node at which to post the error and the node to use for the
10674 '&' substitution. */
10676 void
10678 {
10679 String_Template temp;
10680 String_Pointer sp;
10690 }
10692 /* Similar to post_error, but NODE is the node at which to post the error and
10693 ENT is the node to use for the '&' substitution. */
10695 void
10697 {
10698 String_Template temp;
10699 String_Pointer sp;
10709 }
10711 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
10713 void
10715 {
10718 }
10720 /* Similar to post_error_ne, but T is a GCC tree representing the number to
10721 write. If T represents a constant, the text inside curly brackets in
10722 MSG will be output (presumably including a '^'). Otherwise it will not
10723 be output and the text inside square brackets will be output instead. */
10725 void
10727 {
10734 {
10737 }
10738 else
10742 {
10748 ;
10749 else
10751 }
10756 }
10758 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
10760 void
10763 {
10766 }
10768 /* Return a label to branch to for the exception type in KIND or Empty
10769 if none. */
10771 Entity_Id
10773 {
10775 {
10787 }
10790 }
10792 /* Return the decl for the current elaboration procedure. */
10794 static tree
10796 {
10798 }
10800 /* Return the controlling type of a dispatching subprogram. */
10802 static Entity_Id
10804 {
10805 /* This is modeled on Expand_Interface_Thunk. */
10814 }
10816 /* Return whether we should use an alias for the TARGET of a thunk
10817 in order to make the call generated in the thunk local. */
10819 static bool
10821 {
10822 /* We cannot generate a local call in this case. */
10826 /* The call is already local in this case. */
10831 }
10835 /* Create an alias for TARGET to be used as the target of a thunk. */
10837 static tree
10839 {
10860 }
10862 /* Create the local covariant part of {GNAT,GNU}_THUNK. */
10864 static tree
10866 {
10868 tree gnu_cv_thunk
10874 param_decl;
10888 }
10890 /* Try to create a GNU thunk for {GNAT,GNU}_THUNK and return true on success.
10892 GNU thunks are more efficient than GNAT thunks because they don't call into
10893 the runtime to retrieve the offset used in the displacement operation, but
10894 they are tailored to C++ and thus too limited to support the full range of
10895 thunks generated in Ada. Here's the complete list of limitations:
10897 1. Multi-controlling thunks, i.e thunks with more than one controlling
10898 parameter, are simply not supported.
10900 2. Covariant thunks, i.e. thunks for which the result is also controlling,
10901 are split into a pair of (this, covariant-only) thunks.
10903 3. Variable-offset thunks, i.e. thunks for which the offset depends on the
10904 object and not only on its type, are supported as 2nd class citizens.
10906 4. External thunks, i.e. thunks for which the target is not declared in
10907 the same unit as the thunk, are supported as 2nd class citizens.
10909 5. Local thunks, i.e. thunks generated for a local type, are supported as
10910 2nd class citizens. */
10912 static bool
10914 {
10915 /* We use the Thunk_Target to compute the properties of the thunk. */
10918 /* Check that the first formal of the target is the only controlling one. */
10928 /* Look for the types that control the target and the thunk. */
10932 /* We must have an interface type at this point. */
10935 /* Now compute whether the former covers the latter. */
10936 const Entity_Id gnat_interface_tag
10938 tree gnu_interface_tag
10942 tree gnu_interface_offset
10945 /* There are three ways to retrieve the offset between the interface view
10946 and the base object. Either the controlling type covers the interface
10947 type and the offset of the corresponding tag is fixed, in which case it
10948 can be statically encoded in the thunk (see FIXED_OFFSET below). Or the
10949 controlling type doesn't cover the interface type but is of fixed size,
10950 in which case the offset is stored in the dispatch table, two pointers
10951 above the dispatch table address (see VIRTUAL_VALUE below). Otherwise,
10952 the offset is variable and is stored right after the tag in every object
10953 (see INDIRECT_OFFSET below). See also a-tags.ads for more details. */
10955 tree virtual_offset;
10958 {
10963 }
10966 {
10971 }
10972 else
10973 {
10974 /* Covariant thunks with variable offset are not supported. */
10982 }
10984 /* But we generate a call to the Thunk_Entity in the thunk. */
10985 tree gnu_target
10988 /* If the target is local, then thunk and target must have the same context
10989 because cgraph_node::expand_thunk can only forward the static chain. */
10994 /* If the target returns by invisible reference and is external, apply the
10995 same transformation as Subprogram_Body_to_gnu here. */
10999 {
11003 }
11005 /* The thunk expander requires the return types of thunk and target to be
11006 compatible, which is not fully the case with the CICO mechanism. */
11008 {
11013 }
11017 /* We may also need to create an alias for the target in order to make
11018 the call local, depending on the linkage of the target. */
11023 /* If the return type of the target is a controlling type, then we need
11024 both an usual this thunk and a covariant thunk in this order:
11026 this thunk --> covariant thunk --> target
11028 For covariant thunks, we can only handle a fixed offset. */
11030 {
11038 }
11045 }
11047 /* Initialize the table that maps GNAT codes to GCC codes for simple
11048 binary and unary operations. */
11050 static void
11052 {
11077 }