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1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * T R A N S *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2015, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License distributed with GNAT; see file COPYING3. If not see *
19 * <http://www.gnu.org/licenses/>. *
20 * *
21 * GNAT was originally developed by the GNAT team at New York University. *
22 * Extensive contributions were provided by Ada Core Technologies Inc. *
23 * *
24 ****************************************************************************/
67 /* We should avoid allocating more than ALLOCA_THRESHOLD bytes via alloca,
68 for fear of running out of stack space. If we need more, we use xmalloc
69 instead. */
70 #define ALLOCA_THRESHOLD 1000
72 /* Pointers to front-end tables accessed through macros. */
83 /* Highest number in the front-end node table. */
86 /* Current node being treated, in case abort called. */
87 Node_Id error_gnat_node;
89 /* True when gigi is being called on an analyzed but unexpanded
90 tree, and the only purpose of the call is to properly annotate
91 types with representation information. */
94 /* List of N_Validate_Unchecked_Conversion nodes in the unit. */
97 /* When not optimizing, we cache the 'First, 'Last and 'Length attributes
98 of unconstrained array IN parameters to avoid emitting a great deal of
99 redundant instructions to recompute them each time. */
103 tree first;
104 tree last;
105 tree length;
106 };
113 bitmap named_ret_val;
116 };
118 #define f_parm_attr_cache \
119 DECL_STRUCT_FUNCTION (current_function_decl)->language->parm_attr_cache
121 #define f_named_ret_val \
122 DECL_STRUCT_FUNCTION (current_function_decl)->language->named_ret_val
124 #define f_other_ret_val \
125 DECL_STRUCT_FUNCTION (current_function_decl)->language->other_ret_val
127 #define f_gnat_ret \
128 DECL_STRUCT_FUNCTION (current_function_decl)->language->gnat_ret
130 /* A structure used to gather together information about a statement group.
131 We use this to gather related statements, for example the "then" part
132 of a IF. In the case where it represents a lexical scope, we may also
133 have a BLOCK node corresponding to it and/or cleanups. */
140 };
144 /* List of unused struct stmt_group nodes. */
147 /* A structure used to record information on elaboration procedures
148 we've made and need to process.
150 ??? gnat_node should be Node_Id, but gengtype gets confused. */
156 };
160 /* Stack of exception pointer variables. Each entry is the VAR_DECL
161 that stores the address of the raised exception. Nonzero means we
162 are in an exception handler. Not used in the zero-cost case. */
165 /* In ZCX case, current exception pointer. Used to re-raise it. */
168 /* Stack for storing the current elaboration procedure decl. */
171 /* Stack of labels to be used as a goto target instead of a return in
172 some functions. See processing for N_Subprogram_Body. */
175 /* Stack of variable for the return value of a function with copy-in/copy-out
176 parameters. See processing for N_Subprogram_Body. */
179 /* Structure used to record information for a range check. */
181 tree low_bound;
182 tree high_bound;
183 tree disp;
185 tree type;
186 tree invariant_cond;
187 tree inserted_cond;
188 };
193 /* Structure used to record information for a loop. */
195 tree stmt;
196 tree loop_var;
197 tree low_bound;
198 tree high_bound;
203 };
208 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
211 /* The stacks for N_{Push,Pop}_*_Label. */
216 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
251 /* Hooks for debug info back-ends, only supported and used in a restricted set
252 of configurations. */
255 \f
256 /* This is the main program of the back-end. It sets up all the table
257 structures and then generates code. */
259 void
272 Nat number_file,
274 Entity_Id standard_boolean,
275 Entity_Id standard_integer,
276 Entity_Id standard_character,
277 Entity_Id standard_long_long_float,
278 Entity_Id standard_exception_type,
279 Int gigi_operating_mode)
280 {
281 Node_Id gnat_iter;
282 Entity_Id gnat_literal;
302 {
303 /* Use the identifier table to make a permanent copy of the filename as
304 the name table gets reallocated after Gigi returns but before all the
305 debugging information is output. The __gnat_to_canonical_file_spec
306 call translates filenames from pragmas Source_Reference that contain
307 host style syntax not understood by gdb. */
309 = IDENTIFIER_POINTER
310 (get_identifier
311 (__gnat_to_canonical_file_spec
314 /* We rely on the order isomorphism between files and line maps. */
317 /* We create the line map for a source file at once, with a fixed number
318 of columns chosen to avoid jumping over the next power of 2. */
323 }
327 /* Declare the name of the compilation unit as the first global
328 name in order to make the middle-end fully deterministic. */
332 /* Initialize ourselves. */
337 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
338 errors. */
340 {
343 }
345 /* Enable GNAT stack checking method if needed */
349 /* Retrieve alignment settings. */
353 /* Record the builtin types. Define `integer' and `character' first so that
354 dbx will output them first. */
360 /* Save the type we made for integer as the type for Standard.Integer. */
365 /* Likewise for character as the type for Standard.Character. */
370 /* Likewise for boolean as the type for Standard.Boolean. */
392 /* Now declare run-time functions. */
395 /* malloc is a function declaration tree for a function to allocate
396 memory. */
397 malloc_decl
399 ftype,
404 /* free is a function declaration tree for a function to free memory. */
405 free_decl
408 ptr_type_node,
409 NULL_TREE),
413 /* This is used for 64-bit multiplication with overflow checking. */
415 mulv64_decl
422 /* Name of the _Parent field in tagged record types. */
425 /* Name of the Exception_Data type defined in System.Standard_Library. */
426 exception_data_name_id
429 /* Make the types and functions used for exception processing. */
432 jmpbuf_type
438 /* Functions to get and set the jumpbuf pointer for the current thread. */
439 get_jmpbuf_decl
440 = create_subprog_decl
446 set_jmpbuf_decl
447 = create_subprog_decl
450 NULL_TREE),
454 get_excptr_decl
455 = create_subprog_decl
458 NULL_TREE),
465 {
468 }
471 /* setjmp returns an integer and has one operand, which is a pointer to
472 a jmpbuf. */
473 setjmp_decl
474 = create_subprog_decl
477 NULL_TREE),
483 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
484 address. */
485 update_setjmp_buf_decl
486 = create_subprog_decl
494 /* Indicate that it never returns. */
495 raise_nodefer_decl
496 = create_subprog_decl
500 NULL_TREE),
504 /* Indicate that these never return. */
505 reraise_zcx_decl
511 set_exception_parameter_decl
512 = create_subprog_decl
515 NULL_TREE),
519 /* Hooks to call when entering/leaving an exception handler. */
522 begin_handler_decl
528 end_handler_decl
534 unhandled_except_decl
540 /* Dummy objects to materialize "others" and "all others" in the exception
541 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
542 the types to use. */
543 others_decl
550 all_others_decl
557 unhandled_others_decl
564 /* If in no exception handlers mode, all raise statements are redirected to
565 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
566 this procedure will never be called in this mode. */
568 {
569 tree decl
570 = create_subprog_decl
573 build_pointer_type
580 }
581 else
582 {
583 /* Otherwise, make one decl for each exception reason. */
589 i == CE_Index_Check_Failed
593 }
595 /* Build the special descriptor type and its null node if needed. */
597 {
609 {
610 tree field
617 elt--;
618 }
623 }
625 longest_float_type_node
630 /* Install the builtins we might need, either internally or as
631 user available facilities for Intrinsic imports. */
639 /* Process any Pragma Ident for the main unit. */
644 /* If we are using the GCC exception mechanism, let GCC know. */
648 /* Initialize the GCC support for FP operations. */
651 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
655 /* Save the current optimization options again after the above possible
656 global_options changes. */
660 /* Now translate the compilation unit proper. */
663 /* Disable -Waggressive-loop-optimizations since we implement our own
664 version of the warning. */
667 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
668 the very end to avoid having to second-guess the front-end when we run
669 into dummy nodes during the regular processing. */
674 /* Finally see if we have any elaboration procedures to deal with. */
676 {
679 /* We should have a BIND_EXPR but it may not have any statements in it.
680 If it doesn't have any, we have nothing to do except for setting the
681 flag on the GNAT node. Otherwise, process the function as others. */
687 else
688 {
692 }
693 }
695 /* Destroy ourselves. */
699 /* We cannot track the location of errors past this point. */
701 }
702 \f
703 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
704 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
706 static tree
708 {
717 {
719 ftype
721 build_pointer_type
724 }
725 else
726 {
731 ftype
733 build_pointer_type
737 }
739 /* Indicate that it never returns. */
740 result
747 }
748 \f
749 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
750 an N_Attribute_Reference. */
752 static int
754 {
756 {
796 }
797 }
799 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
800 is the type that will be used for GNAT_NODE in the translated GNU tree.
801 CONSTANT indicates whether the underlying object represented by GNAT_NODE
802 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
803 whether its value is the address of a constant and ALIASED whether it is
804 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
806 The function climbs up the GNAT tree starting from the node and returns 1
807 upon encountering a node that effectively requires an lvalue downstream.
808 It returns int instead of bool to facilitate usage in non-purely binary
809 logic contexts. */
811 static int
814 {
818 {
828 /* If the parameter is by reference, an lvalue is required. */
834 /* Only the array expression can require an lvalue. */
838 /* ??? Consider that referencing an indexed component with a variable
839 index forces the whole aggregate to memory. Note that testing only
840 for literals is conservative, any static expression in the RM sense
841 could probably be accepted with some additional work. */
851 /* ... fall through ... */
854 /* Only the array expression can require an lvalue. */
868 /* We need to preserve addresses through a renaming. */
872 /* We cannot use a constructor if this is an atomic object because
873 the actual assignment might end up being done component-wise. */
877 /* We don't use a constructor if this is a class-wide object
878 because the effective type of the object is the equivalent
879 type of the class-wide subtype and it smashes most of the
880 data into an array of bytes to which we cannot convert. */
885 /* We cannot use a constructor if the LHS is an atomic object because
886 the actual assignment might end up being done component-wise. */
897 /* ... fall through ... */
901 /* We must look through all conversions because we may need to bypass
902 an intermediate conversion that is meant to be purely formal. */
908 /* We should only reach here through the N_Qualified_Expression case.
909 Force an lvalue for composite types since a block-copy to the newly
910 allocated area of memory is made. */
914 /* We look through dereferences for address of constant because we need
915 to handle the special cases listed above. */
921 /* ... fall through ... */
925 }
928 }
930 /* Return true if T is a constant DECL node that can be safely replaced
931 by its initializer. */
933 static bool
935 {
939 /* Return false for aggregate types that contain a placeholder since
940 their initializers cannot be manipulated easily. */
947 }
949 /* Return an expression equivalent to EXP but where constant DECL nodes
950 have been replaced by their initializer. */
952 static tree
954 {
956 tree op0;
959 {
978 /* If the index is not itself constant, then nothing can be folded. */
999 }
1002 }
1004 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1005 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1006 to where we should place the result type. */
1008 static tree
1010 {
1014 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1015 specific circumstances only, so evaluated lazily. < 0 means
1016 unknown, > 0 means known true, 0 means known false. */
1019 /* If GNAT_NODE is a constant, whether we should use the initialization
1020 value instead of the constant entity, typically for scalars with an
1021 address clause when the parent doesn't require an lvalue. */
1024 /* If the Etype of this node does not equal the Etype of the Entity,
1025 something is wrong with the entity map, probably in generic
1026 instantiation. However, this does not apply to types. Since we sometime
1027 have strange Ekind's, just do this test for objects. Also, if the Etype of
1028 the Entity is private, the Etype of the N_Identifier is allowed to be the
1029 full type and also we consider a packed array type to be the same as the
1030 original type. Similarly, a class-wide type is equivalent to a subtype of
1031 itself. Finally, if the types are Itypes, one may be a copy of the other,
1032 which is also legal. */
1048 == Packed_Array_Impl_Type
1057 /* If this is a reference to a deferred constant whose partial view is an
1058 unconstrained private type, the proper type is on the full view of the
1059 constant, not on the full view of the type, which may be unconstrained.
1061 This may be a reference to a type, for example in the prefix of the
1062 attribute Position, generated for dispatching code (see Make_DT in
1063 exp_disp,adb). In that case we need the type itself, not is parent,
1064 in particular if it is a derived type */
1071 {
1074 }
1075 else
1076 {
1077 /* We want to use the Actual_Subtype if it has already been elaborated,
1078 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1079 simplify things. */
1087 else
1089 }
1091 /* Expand the type of this identifier first, in case it is an enumeral
1092 literal, which only get made when the type is expanded. There is no
1093 order-of-elaboration issue here. */
1096 /* If this is a non-imported elementary constant with an address clause,
1097 retrieve the value instead of a pointer to be dereferenced unless
1098 an lvalue is required. This is generally more efficient and actually
1099 required if this is a static expression because it might be used
1100 in a context where a dereference is inappropriate, such as a case
1101 statement alternative or a record discriminant. There is no possible
1102 volatile-ness short-circuit here since Volatile constants must be
1103 imported per C.6. */
1108 {
1112 }
1115 {
1116 /* If this is a deferred constant, the initializer is attached to
1117 the full view. */
1122 }
1123 else
1126 /* Some objects (such as parameters passed by reference, globals of
1127 variable size, and renamed objects) actually represent the address
1128 of the object. In that case, we must do the dereference. Likewise,
1129 deal with parameters to foreign convention subprograms. */
1134 {
1137 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1140 gnu_result
1143 /* If it's a CONST_DECL, return the underlying constant like below. */
1150 /* If it's a renaming pointer, get to the renamed object. */
1156 /* Otherwise, do the final dereference. */
1157 else
1158 {
1168 }
1169 }
1171 /* If we have a constant declaration and its initializer, try to return the
1172 latter to avoid the need to call fold in lots of places and the need for
1173 elaboration code if this identifier is used as an initializer itself. */
1175 {
1181 /* If there is a (corresponding) variable or this is the address of a
1182 constant, we only want to return the initializer if an lvalue isn't
1183 required. Evaluate this now if we have not already done so. */
1185 require_lvalue
1189 /* Finally retrieve the initializer if this is deemed valid. */
1192 }
1194 /* But for a constant renaming we couldn't do that incrementally for its
1195 definition because of the need to return an lvalue so, if the present
1196 context doesn't itself require an lvalue, we try again here. */
1200 {
1202 require_lvalue
1207 }
1209 /* The GNAT tree has the type of a function set to its result type, so we
1210 adjust here. Also use the type of the result if the Etype is a subtype
1211 that is nominally unconstrained. Likewise if this is a deferred constant
1212 of a discriminated type whose full view can be elaborated statically, to
1213 avoid problematic conversions to the nominal subtype. But remove any
1214 padding from the resulting type. */
1221 {
1225 }
1230 }
1231 \f
1232 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1233 any statements we generate. */
1235 static tree
1237 {
1240 Node_Id gnat_temp;
1242 /* Do nothing if we are just annotating types and check for (and ignore)
1243 unrecognized pragmas. */
1250 {
1252 /* Do nothing at top level: all such variables are already viewable. */
1259 {
1263 machine_mode mode;
1265 #ifdef ASM_COMMENT_START
1267 #endif
1272 /* Use the value only if it fits into a normal register,
1273 otherwise use the address. */
1282 #ifdef ASM_COMMENT_START
1288 NULL);
1291 #endif
1293 asm_constraint,
1294 NULL_TREE,
1295 tree_cons
1303 }
1310 {
1314 {
1337 }
1338 }
1344 {
1362 }
1372 {
1373 Node_Id gnat_expr;
1374 /* Preserve the location of the pragma. */
1378 diagnostic_t kind;
1383 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1385 {
1387 {
1400 }
1403 }
1405 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1407 {
1409 {
1420 }
1422 /* Deal with optional pattern (but ignore Reason => "..."). */
1425 {
1426 /* pragma Warnings (On | Off, Name) is handled differently. */
1431 }
1432 else
1436 }
1438 else
1441 /* This is the same implementation as in the C family of compilers. */
1444 {
1452 {
1455 }
1457 {
1460 }
1462 {
1465 }
1466 }
1467 else
1474 }
1479 }
1482 }
1483 \f
1485 /* Check the inlining status of nested function FNDECL in the current context.
1487 If a non-inline nested function is referenced from an inline external
1488 function, we cannot honor both requests at the same time without cloning
1489 the nested function in the current unit since it is private to its unit.
1490 We could inline it as well but it's probably better to err on the side
1491 of too little inlining.
1493 This must be invoked only on nested functions present in the source code
1494 and not on nested functions generated by the compiler, e.g. finalizers,
1495 because they are not marked inline and we don't want them to block the
1496 inlining of the parent function. */
1498 static void
1500 {
1502 && current_function_decl
1505 {
1511 {
1514 }
1515 else
1516 {
1518 fndecl);
1520 }
1524 }
1525 }
1526 \f
1527 /* Return an expression for the length of TYPE, an integral type, computed in
1528 RESULT_TYPE, another integral type.
1530 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1531 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1532 which would only overflow in much rarer cases, for extremely large arrays
1533 we expect never to encounter in practice. Besides, the former computation
1534 required the use of potentially constraining signed arithmetics while the
1535 latter does not. Note that the comparison must be done in the original
1536 base index type in order to avoid any overflow during the conversion. */
1538 static tree
1540 {
1545 tree length
1551 length
1557 }
1559 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1560 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1561 where we should place the result type. ATTRIBUTE is the attribute ID. */
1563 static tree
1565 {
1571 /* ??? If this is an access attribute for a public subprogram to be used in
1572 a dispatch table, do not translate its type as it's useless in this case
1573 and the parameter types might be incomplete types coming from a limited
1574 context in Ada 2012 (AI05-0151). */
1582 else
1586 /* If the input is a NULL_EXPR, make a new one. */
1588 {
1592 }
1595 {
1598 /* These are just conversions since representation clauses for
1599 enumeration types are handled in the front-end. */
1600 {
1606 }
1611 /* These just add or subtract the constant 1 since representation
1612 clauses for enumeration types are handled in the front-end. */
1617 {
1619 gnu_expr
1620 = emit_check
1622 gnu_expr,
1623 attribute == Attr_Pred
1627 }
1629 gnu_result
1637 /* Conversions don't change addresses but can cause us to miss the
1638 COMPONENT_REF case below, so strip them off. */
1642 /* If we are taking 'Address of an unconstrained object, this is the
1643 pointer to the underlying array. */
1647 /* If we are building a static dispatch table, we have to honor
1648 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1649 with the C++ ABI. We do it in the non-static case as well,
1650 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1653 {
1655 /* Descriptors can only be built here for top-level functions. */
1663 /* If we're not going to build the descriptor, we have to retrieve
1664 the one which will be built by the linker (or by the compiler
1665 later if a static chain is requested). */
1667 {
1670 gnu_result);
1672 }
1679 {
1681 {
1685 }
1686 else
1692 elt--;
1693 }
1697 }
1699 /* ... fall through ... */
1705 gnu_result
1712 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1713 don't try to build a trampoline. */
1715 {
1720 }
1722 /* For 'Access, issue an error message if the prefix is a C++ method
1723 since it can use a special calling convention on some platforms,
1724 which cannot be propagated to the access type. */
1729 gnat_node);
1731 /* For other address attributes applied to a nested function,
1732 find an inner ADDR_EXPR and annotate it so that we can issue
1733 a useful warning with -Wtrampolines. */
1735 {
1740 {
1743 /* Also check the inlining status. */
1746 /* Check that we're not violating the No_Implicit_Dynamic_Code
1747 restriction. Be conservative if we don't know anything
1748 about the trampoline strategy for the target. */
1750 }
1751 }
1755 {
1757 tree gnu_obj_type;
1761 /* If this is fat pointer, the object must have been allocated with the
1762 template in front of the array. So compute the template address; do
1763 it by converting to a thin pointer. */
1765 gnu_ptr
1767 (TYPE_OBJECT_RECORD_TYPE
1769 gnu_ptr);
1773 /* If this is a thin pointer, the object must have been allocated with
1774 the template in front of the array. So compute the template address
1775 and return it. */
1777 gnu_ptr
1779 gnu_ptr,
1781 byte_position
1782 (DECL_CHAIN
1786 }
1795 /* Remove NOPs and conversions between original and packable version
1796 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1797 to see if a COMPONENT_REF was involved. */
1802 == RECORD_TYPE
1811 /* Replace an unconstrained array type with the type of the underlying
1812 array. We can't do this with a call to maybe_unconstrained_array
1813 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1814 use the record type that will be used to allocate the object and its
1815 template. */
1817 {
1821 }
1823 /* If we're looking for the size of a field, return the field size. */
1827 /* Otherwise, if the prefix is an object, or if we are looking for
1828 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1829 GCC size of the type. We make an exception for padded objects,
1830 as we do not take into account alignment promotions for the size.
1831 This is in keeping with the object case of gnat_to_gnu_entity. */
1837 {
1838 /* If this is a dereference and we have a special dynamic constrained
1839 subtype on the prefix, use it to compute the size; otherwise, use
1840 the designated subtype. */
1842 {
1843 Node_Id gnat_actual_subtype
1845 tree gnu_ptr_type
1850 {
1851 tree gnu_actual_obj_type
1853 gnu_type
1855 gnu_actual_obj_type,
1858 }
1859 }
1862 }
1864 /* Otherwise, the result is the RM size of the type. */
1865 else
1868 /* Deal with a self-referential size by returning the maximum size for
1869 a type and by qualifying the size with the object otherwise. */
1871 {
1874 else
1876 }
1878 /* If the type contains a template, subtract its size. */
1884 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1892 {
1905 else
1906 {
1911 /* If the default alignment of "double" or larger scalar types is
1912 specifically capped and there is an alignment clause neither
1913 on the type nor on the prefix itself, return the cap. */
1915 is_capped_double
1918 is_capped_double
1920 else
1930 else
1932 }
1935 }
1944 {
1951 else
1954 }
1956 /* ... fall through ... */
1959 {
1967 /* Make sure any implicit dereference gets done. */
1971 /* We treat unconstrained array In parameters specially. We also note
1972 whether we are dereferencing a pointer to unconstrained array. */
1975 {
1977 /* This is the direct case. */
1983 /* This is the indirect case. Note that we need to be sure that
1984 the access value cannot be null as we'll hoist the load. */
1987 {
1990 }
1991 else
1997 }
1999 /* If the prefix is the view conversion of a constrained array to an
2000 unconstrained form, we retrieve the constrained array because we
2001 might not be able to substitute the PLACEHOLDER_EXPR coming from
2002 the conversion. This can occur with the 'Old attribute applied
2003 to a parameter with an unconstrained type, which gets rewritten
2004 into a constrained local variable very late in the game. */
2007 && !CONTAINS_PLACEHOLDER_P
2010 else
2017 {
2019 tree gnu_type_temp;
2025 ;
2028 }
2035 /* When not optimizing, look up the slot associated with the parameter
2036 and the dimension in the cache and create a new one on failure.
2037 Don't do this when the actual subtype needs debug info (this happens
2038 with -gnatD): in elaborate_expression_1, we create variables that
2039 hold the bounds, so caching attributes isn't very interesting and
2040 causes dependency issues between these variables and cached
2041 expressions. */
2046 {
2052 {
2057 }
2058 }
2060 /* Return the cached expression or build a new one. */
2062 {
2064 {
2067 }
2069 gnu_result
2071 }
2074 {
2076 {
2079 }
2081 gnu_result
2083 }
2086 {
2088 {
2091 }
2093 gnu_result
2095 gnu_result_type);
2096 }
2098 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2099 handling. Note that these attributes could not have been used on
2100 an unconstrained array type. */
2103 /* Cache the expression we have just computed. Since we want to do it
2104 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2105 create the temporary in the outermost binding level. We will make
2106 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2107 paths by forcing its evaluation on entry of the function. */
2109 {
2110 gnu_result
2113 {
2129 }
2130 }
2132 /* Otherwise, evaluate it each time it is referenced. */
2133 else
2135 {
2138 /* If we are dereferencing a pointer to unconstrained array, we
2139 need to capture the value because the pointed-to bounds may
2140 subsequently be released. */
2142 gnu_result
2148 /* Set the source location onto the predicate of the condition
2149 but not if the expression is cached to avoid messing up the
2150 debug info. */
2154 gnat_node);
2159 }
2162 }
2169 {
2170 HOST_WIDE_INT bitsize;
2171 HOST_WIDE_INT bitpos;
2172 tree gnu_offset;
2173 tree gnu_field_bitpos;
2174 tree gnu_field_offset;
2175 tree gnu_inner;
2176 machine_mode mode;
2183 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2184 the result is 0. Don't allow 'Bit on a bare component, though. */
2188 {
2191 }
2193 else
2202 {
2210 {
2211 gnu_field_bitpos
2214 gnu_field_offset
2217 }
2218 }
2220 {
2223 }
2224 else
2225 {
2228 }
2231 {
2245 /* ??? Avoid a large unsigned result that will overflow when
2246 converted to the signed universal_integer. */
2249 else
2250 gnu_result
2257 }
2259 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2260 handling. */
2263 }
2267 {
2273 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2274 a NaN so we implement the semantics of C99 f{min,max} to make it
2275 predictable in this case: if either operand is a NaN, the other
2276 is returned; if both operands are NaN's, a NaN is returned. */
2279 {
2285 /* If the operands have side-effects, they need to be evaluated
2286 only once in spite of the multiple references in the result. */
2294 integer_zero_node);
2298 integer_zero_node);
2308 /* If the operands have side-effects, they need to be evaluated
2309 before doing the tests above since the place they otherwise
2310 would end up being evaluated at run time could be wrong. */
2312 gnu_result
2316 gnu_result
2318 }
2319 else
2323 }
2349 /* Note this size cannot be self-referential. */
2359 /* What we want is the offset of the ARRAY field in the record
2360 that the thin pointer designates. */
2368 /* This is just a zero cast to the pointer type for our prefix and
2369 dereferenced. */
2371 gnu_result
2374 integer_zero_node));
2379 {
2386 {
2391 ;
2392 }
2400 && (DECL_BY_COMPONENT_PTR_P
2404 }
2408 /* We treat Model as identical to Machine. This is true for at least
2409 IEEE and some other nice floating-point systems. */
2411 /* ... fall through ... */
2414 /* The trick is to force the compiler to store the result in memory so
2415 that we do not have extra precision used. But do this only when this
2416 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2417 the type is lower than that of the longest floating-point type. */
2424 && fp_arith_may_widen
2427 {
2429 tree field
2439 asm_expr
2451 gnu_result
2455 }
2462 /* This can be a random address so build an alias-all pointer type. */
2463 gnu_expr
2466 gnu_expr);
2471 /* This abort means that we have an unimplemented attribute. */
2473 }
2475 /* If this is an attribute where the prefix was unused, force a use of it if
2476 it has a side-effect. But don't do it if the prefix is just an entity
2477 name. However, if an access check is needed, we must do it. See second
2478 example in AARM 11.6(5.e). */
2482 gnu_result
2487 }
2488 \f
2489 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2490 to a GCC tree, which is returned. */
2492 static tree
2494 {
2496 Node_Id gnat_when;
2497 location_t end_locus;
2503 /* The range of values in a case statement is determined by the rules in
2504 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2505 of the expression. One exception arises in the case of a simple name that
2506 is parenthesized. This still has the Etype of the name, but since it is
2507 not a name, para 7 does not apply, and we need to go to the base type.
2508 This is the only case where parenthesization affects the dynamic
2509 semantics (i.e. the range of possible values at run time that is covered
2510 by the others alternative).
2512 Another exception is if the subtype of the expression is non-static. In
2513 that case, we also have to use the base type. */
2519 /* We build a SWITCH_EXPR that contains the code with interspersed
2520 CASE_LABEL_EXPRs for each label. */
2529 {
2531 Node_Id gnat_choice;
2533 /* First compile all the different case choices for the current WHEN
2534 alternative. */
2538 {
2543 {
2558 /* This represents either a subtype range or a static value of
2559 some kind; Ekind says which. */
2561 {
2567 }
2569 /* ... fall through ... */
2581 }
2583 /* Everything should be folded into constants at this point. */
2588 gnat_choice);
2590 }
2592 /* This construct doesn't define a scope so we shouldn't push a binding
2593 level around the statement list. Except that we have always done so
2594 historically and this makes it possible to reduce stack usage. As a
2595 compromise, we keep doing it for case statements, for which this has
2596 never been problematic, but not for case expressions in Ada 2012. */
2598 {
2599 const bool is_case_expression
2601 tree group
2606 {
2611 }
2612 }
2613 }
2615 /* Now emit a definition of the label the cases branch to, if any. */
2622 }
2623 \f
2624 /* Return true if we are in the body of a loop. */
2628 {
2630 }
2632 /* Find out whether EXPR is a simple additive expression based on the iteration
2633 variable of some enclosing loop in the current function. If so, return the
2634 loop and set *DISP to the displacement and *NEG_P to true if this is for a
2635 subtraction; otherwise, return NULL. */
2639 {
2646 {
2652 }
2653 else
2654 {
2660 }
2677 }
2679 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2680 false, or the maximum value if MAX is true, of TYPE. */
2682 static bool
2684 {
2691 val = (max
2700 else
2702 }
2704 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2705 If REVERSE is true, minimum value is taken as maximum value. */
2709 {
2711 }
2713 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2714 If REVERSE is true, maximum value is taken as minimum value. */
2718 {
2720 }
2722 /* Return true if VAL1 can be lower than VAL2. */
2724 static bool
2726 {
2740 }
2742 /* Replace EXPR1 and EXPR2 by invariant expressions if possible. Return
2743 true if both expressions have been replaced and false otherwise. */
2745 static bool
2747 {
2758 }
2760 /* Helper function for walk_tree, used by independent_iterations_p below. */
2762 static tree
2764 {
2768 /* No need to walk into types or decls. */
2776 }
2778 /* Return true if STMT_LIST generates independent iterations in a loop. */
2780 static bool
2782 {
2783 tree_stmt_iterator tsi;
2786 tree iter;
2792 /* Scan the list and return false on anything that is not either a check
2793 or an assignment to a parameter with restricted aliasing. */
2795 {
2799 {
2801 {
2810 }
2813 {
2826 }
2830 }
2831 }
2833 /* At this point we know that the list contains only statements that will
2834 modify parameters with restricted aliasing. Check that the statements
2835 don't at the time read from these parameters. */
2841 }
2843 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2844 to a GCC tree, which is returned. */
2846 static tree
2848 {
2855 tree gnu_result;
2857 /* Push the loop_info structure associated with the LOOP_STMT. */
2860 /* Set location information for statement and end label. */
2866 /* Save the statement for later reuse. */
2870 /* Set the condition under which the loop must keep going.
2871 For the case "LOOP .... END LOOP;" the condition is always true. */
2873 ;
2875 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2880 /* Otherwise we have an iteration scheme and the condition is given by the
2881 bounds of the subtype of the iteration variable. */
2882 else
2883 {
2897 /* We must disable modulo reduction for the iteration variable, if any,
2898 in order for the loop comparison to be effective. */
2900 {
2906 }
2907 else
2908 {
2914 }
2916 /* We use two different strategies to translate the loop, depending on
2917 whether optimization is enabled.
2919 If it is, we generate the canonical loop form expected by the loop
2920 optimizer and the loop vectorizer, which is the do-while form:
2922 ENTRY_COND
2923 loop:
2924 TOP_UPDATE
2925 BODY
2926 BOTTOM_COND
2927 GOTO loop
2929 This avoids an implicit dependency on loop header copying and makes
2930 it possible to turn BOTTOM_COND into an inequality test.
2932 If optimization is disabled, loop header copying doesn't come into
2933 play and we try to generate the loop form with the fewer conditional
2934 branches. First, the default form, which is:
2936 loop:
2937 TOP_COND
2938 BODY
2939 BOTTOM_UPDATE
2940 GOTO loop
2942 It should catch most loops with constant ending point. Then, if we
2943 cannot, we try to generate the shifted form:
2945 loop:
2946 TOP_COND
2947 TOP_UPDATE
2948 BODY
2949 GOTO loop
2951 which should catch loops with constant starting point. Otherwise, if
2952 we cannot, we generate the fallback form:
2954 ENTRY_COND
2955 loop:
2956 BODY
2957 BOTTOM_COND
2958 BOTTOM_UPDATE
2959 GOTO loop
2961 which works in all cases. */
2964 {
2965 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2966 overflow. */
2968 ;
2970 /* Otherwise, use the do-while form with the help of a special
2971 induction variable in the unsigned version of the base type
2972 or the unsigned version of the size type, whichever is the
2973 largest, in order to have wrap-around arithmetics for it. */
2974 else
2975 {
2978 gnu_base_type
2980 else
2987 }
2989 gnu_first
2991 gnu_one_node);
2994 }
2995 else
2996 {
2997 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2999 ;
3001 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
3002 GNU_LAST-1 does. */
3005 {
3006 gnu_first
3008 gnu_one_node);
3009 gnu_last
3011 gnu_one_node);
3013 }
3015 /* Otherwise, use the fallback form. */
3016 else
3018 }
3020 /* If we use the BOTTOM_COND, we can turn the test into an inequality
3021 test but we may have to add ENTRY_COND to protect the empty loop. */
3023 {
3026 {
3027 gnu_cond_expr
3033 }
3034 }
3036 /* Open a new nesting level that will surround the loop to declare the
3037 iteration variable. */
3041 /* If we use the special induction variable, create it and set it to
3042 its initial value. Morever, the regular iteration variable cannot
3043 itself be initialized, lest the initial value wrapped around. */
3045 {
3046 gnu_loop_iv
3050 }
3051 else
3054 /* Declare the iteration variable and set it to its initial value. */
3059 {
3062 }
3067 /* Do all the arithmetics in the base type. */
3070 /* Set either the top or bottom exit condition. */
3074 gnu_last);
3075 else
3078 gnu_last);
3080 /* Set either the top or bottom update statement and give it the source
3081 location of the iteration for better coverage info. */
3083 {
3084 gnu_stmt
3091 gnu_stmt
3093 gnu_loop_iv);
3097 }
3098 else
3099 {
3100 gnu_stmt
3106 }
3107 }
3109 /* If the loop was named, have the name point to this loop. In this case,
3110 the association is not a DECL node, but the end label of the loop. */
3114 /* Make the loop body into its own block, so any allocated storage will be
3115 released every iteration. This is needed for stack allocation. */
3120 /* If we have an iteration scheme, then we are in a statement group. Add
3121 the LOOP_STMT to it, finish it and make it the "loop". */
3123 {
3124 /* First, if we have computed invariant conditions for range (or index)
3125 checks applied to the iteration variable, find out whether they can
3126 be evaluated to false at compile time; otherwise, if there are not
3127 too many of them, combine them with the original checks. If loop
3128 unswitching is enabled, do not require the loop bounds to be also
3129 invariant, as their evaluation will still be ahead of the loop. */
3132 {
3137 {
3141 {
3144 gnu_adjusted_low
3147 low_ok
3150 }
3151 else
3155 {
3158 gnu_adjusted_high
3161 high_ok
3164 }
3165 else
3168 tree range_ok
3172 rci->invariant_cond
3177 else
3178 n_remaining_checks++;
3179 }
3181 /* Note that loop unswitching can only be applied a small number of
3182 times to a given loop (PARAM_MAX_UNSWITCH_LEVEL default to 3). */
3187 {
3192 }
3193 }
3195 /* Second, if loop vectorization is enabled and the iterations of the
3196 loop can easily be proved as independent, mark the loop. */
3198 && flag_tree_loop_vectorize
3205 }
3207 /* If we have an outer COND_EXPR, that's our result and this loop is its
3208 "true" statement. Otherwise, the result is the LOOP_STMT. */
3210 {
3214 }
3215 else
3221 }
3222 \f
3223 /* This page implements a form of Named Return Value optimization modelled
3224 on the C++ optimization of the same name. The main difference is that
3225 we disregard any semantical considerations when applying it here, the
3226 counterpart being that we don't try to apply it to semantically loaded
3227 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3229 We consider a function body of the following GENERIC form:
3231 return_type R1;
3232 [...]
3233 RETURN_EXPR [<retval> = ...]
3234 [...]
3235 RETURN_EXPR [<retval> = R1]
3236 [...]
3237 return_type Ri;
3238 [...]
3239 RETURN_EXPR [<retval> = ...]
3240 [...]
3241 RETURN_EXPR [<retval> = Ri]
3242 [...]
3244 and we try to fulfill a simple criterion that would make it possible to
3245 replace one or several Ri variables with the RESULT_DECL of the function.
3247 The first observation is that RETURN_EXPRs that don't directly reference
3248 any of the Ri variables on the RHS of their assignment are transparent wrt
3249 the optimization. This is because the Ri variables aren't addressable so
3250 any transformation applied to them doesn't affect the RHS; moreover, the
3251 assignment writes the full <retval> object so existing values are entirely
3252 discarded.
3254 This property can be extended to some forms of RETURN_EXPRs that reference
3255 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3256 case, in particular when function calls are involved.
3258 Therefore the algorithm is as follows:
3260 1. Collect the list of candidates for a Named Return Value (Ri variables
3261 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3262 other expressions on the RHS of such assignments.
3264 2. Prune the members of the first list (candidates) that are referenced
3265 by a member of the second list (expressions).
3267 3. Extract a set of candidates with non-overlapping live ranges from the
3268 first list. These are the Named Return Values.
3270 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3271 Named Return Values in the function with the RESULT_DECL.
3273 If the function returns an unconstrained type, things are a bit different
3274 because the anonymous return object is allocated on the secondary stack
3275 and RESULT_DECL is only a pointer to it. Each return object can be of a
3276 different size and is allocated separately so we need not care about the
3277 aforementioned overlapping issues. Therefore, we don't collect the other
3278 expressions and skip step #2 in the algorithm. */
3280 struct nrv_data
3281 {
3282 bitmap nrv;
3283 tree result;
3284 Node_Id gnat_ret;
3286 };
3288 /* Return true if T is a Named Return Value. */
3292 {
3294 }
3296 /* Helper function for walk_tree, used by finalize_nrv below. */
3298 static tree
3300 {
3304 /* No need to walk into types or decls. */
3312 }
3314 /* Prune Named Return Values in BLOCK and return true if there is still a
3315 Named Return Value in BLOCK or one of its sub-blocks. */
3317 static bool
3319 {
3321 tree t;
3323 /* First recurse on the sub-blocks. */
3327 /* Then make sure to keep at most one NRV per block. */
3330 {
3333 else
3335 }
3338 }
3340 /* Helper function for walk_tree, used by finalize_nrv below. */
3342 static tree
3344 {
3348 /* No need to walk into types. */
3352 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3353 nop, but differs from using NULL_TREE in that it indicates that we care
3354 about the value of the RESULT_DECL. */
3357 {
3360 /* If this is the temporary created for a return value with variable
3361 size in Call_to_gnu, we replace the RHS with the init expression. */
3366 {
3369 }
3370 else
3373 /* Strip useless conversions around the return value. */
3378 {
3381 else
3383 }
3384 }
3386 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3387 if needed. */
3390 {
3394 {
3399 }
3400 else
3404 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3407 /* ??? Kludge to avoid an assertion failure during inlining. */
3410 }
3412 /* And replace all uses of NRVs with the RESULT_DECL. */
3416 /* Avoid walking into the same tree more than once. Unfortunately, we
3417 can't just use walk_tree_without_duplicates because it would only
3418 call us for the first occurrence of NRVs in the function body. */
3423 }
3425 /* Likewise, but used when the function returns an unconstrained type. */
3427 static tree
3429 {
3433 /* No need to walk into types. */
3437 /* We need to see the DECL_EXPR of NRVs before any other references so we
3438 walk the body of BIND_EXPR before walking its variables. */
3442 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3443 return value built by the allocator instead of the whole construct. */
3446 {
3449 /* This is the construct returned by the allocator. */
3452 {
3457 else
3459 }
3461 /* Strip useless conversions around the return value. */
3466 /* Strip unpadding around the return value. */
3471 /* Assign the new return value to the RESULT_DECL. */
3475 }
3477 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3478 into a new variable. */
3481 {
3488 /* Create an artificial context to build the allocation. */
3493 /* This will return a COMPOUND_EXPR with the allocation in the first
3494 arm and the final return value in the second arm. */
3501 /* The new variable is built as a reference to the allocated space. */
3502 new_var
3508 {
3511 /* The new initial value is a COMPOUND_EXPR with the allocation in
3512 the first arm and the value of P_ARRAY in the second arm. */
3518 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3525 }
3526 else
3527 {
3528 /* The new initial value is just the allocation. */
3531 }
3535 /* Destroy the artificial context and insert the new statements. */
3540 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3545 /* Save the new return value and the dereference of NEW_VAR. */
3549 /* ??? Kludge to avoid messing up during inlining. */
3551 }
3553 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3557 /* Avoid walking into the same tree more than once. Unfortunately, we
3558 can't just use walk_tree_without_duplicates because it would only
3559 call us for the first occurrence of NRVs in the function body. */
3564 }
3566 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3567 contains the candidates for Named Return Value and OTHER is a list of
3568 the other return values. GNAT_RET is a representative return node. */
3570 static void
3572 {
3575 walk_tree_fn func;
3577 tree iter;
3579 /* We shouldn't be applying the optimization to return types that we aren't
3580 allowed to manipulate freely. */
3583 /* Prune the candidates that are referenced by other return values. */
3593 /* Prune also the candidates that are referenced by nested functions. */
3601 /* Extract a set of NRVs with non-overlapping live ranges. */
3605 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3612 else
3616 }
3618 /* Return true if RET_VAL can be used as a Named Return Value for the
3619 anonymous return object RET_OBJ. */
3621 static bool
3623 {
3643 }
3645 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3646 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3647 around RESULT_OBJ, which may be null in this case. */
3649 static tree
3651 {
3652 tree result_expr;
3655 {
3656 /* The gimplifier explicitly enforces the following invariant:
3658 RETURN_EXPR
3659 |
3660 INIT_EXPR
3661 / \
3662 / \
3663 RET_OBJ ...
3665 As a consequence, type consistency dictates that we use the type
3666 of the RET_OBJ as the operation type. */
3669 /* Convert the right operand to the operation type. Note that this is
3670 the transformation applied in the INIT_EXPR case of build_binary_op,
3671 with the assumption that the type cannot involve a placeholder. */
3675 /* We always can use an INIT_EXPR for the return object. */
3678 /* If the function returns an aggregate type, find out whether this is
3679 a candidate for Named Return Value. If so, record it. Otherwise,
3680 if this is an expression of some kind, record it elsewhere. */
3686 {
3687 /* Recognize the temporary created for a return value with variable
3688 size in Call_to_gnu. We want to eliminate it if possible. */
3695 /* Strip useless conversions around the return value. */
3699 /* Now apply the test to the return value. */
3701 {
3705 }
3707 /* Note that we need not care about CONSTRUCTORs here, as they are
3708 totally transparent given the read-compose-write semantics of
3709 assignments from CONSTRUCTORs. */
3712 }
3713 }
3714 else
3718 }
3719 \f
3720 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3721 don't return anything. */
3723 static void
3725 {
3726 /* Defining identifier of a parameter to the subprogram. */
3727 Entity_Id gnat_param;
3728 /* The defining identifier for the subprogram body. Note that if a
3729 specification has appeared before for this body, then the identifier
3730 occurring in that specification will also be a defining identifier and all
3731 the calls to this subprogram will point to that specification. */
3732 Entity_Id gnat_subprog_id
3735 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3736 tree gnu_subprog_decl;
3737 /* Its RESULT_DECL node. */
3738 tree gnu_result_decl;
3739 /* Its FUNCTION_TYPE node. */
3740 tree gnu_subprog_type;
3741 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3742 tree gnu_cico_list;
3743 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3745 tree gnu_result;
3746 location_t locus;
3750 /* If this is a generic object or if it has been eliminated,
3751 ignore it. */
3757 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3758 the already-elaborated tree node. However, if this subprogram had its
3759 elaboration deferred, we will already have made a tree node for it. So
3760 treat it as not being defined in that case. Such a subprogram cannot
3761 have an address clause or a freeze node, so this test is safe, though it
3762 does disable some otherwise-useful error checking. */
3763 gnu_subprog_decl
3773 /* If the function returns by invisible reference, make it explicit in the
3774 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3776 {
3780 }
3782 /* Set the line number in the decl to correspond to that of the body. */
3786 /* Initialize the information structure for the function. */
3795 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3796 properly copied out by the return statement. We do this by making a new
3797 block and converting any return into a goto to a label at the end of the
3798 block. */
3800 {
3809 /* If this is a function with copy-in/copy-out parameters and which does
3810 not return by invisible reference, we also need a variable for the
3811 return value to be placed. */
3813 {
3814 tree gnu_return_type
3817 gnu_return_var
3823 }
3827 /* See whether there are parameters for which we don't have a GCC tree
3828 yet. These must be Out parameters. Make a VAR_DECL for them and
3829 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3830 We can match up the entries because TYPE_CI_CO_LIST is in the order
3831 of the parameters. */
3836 {
3838 tree gnu_decl;
3840 /* Skip any entries that have been already filled in; they must
3841 correspond to In Out parameters. */
3845 /* Do any needed dereferences for by-ref objects. */
3851 /* Do any needed references for padded types. */
3854 }
3855 }
3856 else
3859 /* Get a tree corresponding to the code for the subprogram. */
3865 /* Generate the code of the subprogram itself. A return statement will be
3866 present and any Out parameters will be handled there. */
3871 /* If we populated the parameter attributes cache, we need to make sure that
3872 the cached expressions are evaluated on all the possible paths leading to
3873 their uses. So we force their evaluation on entry of the function. */
3876 {
3883 {
3890 }
3896 }
3898 /* If we are dealing with a return from an Ada procedure with parameters
3899 passed by copy-in/copy-out, we need to return a record containing the
3900 final values of these parameters. If the list contains only one entry,
3901 return just that entry though.
3903 For a full description of the copy-in/copy-out parameter mechanism, see
3904 the part of the gnat_to_gnu_entity routine dealing with the translation
3905 of subprograms.
3907 We need to make a block that contains the definition of that label and
3908 the copying of the return value. It first contains the function, then
3909 the label and copy statement. */
3911 {
3912 const Node_Id gnat_end_label
3921 /* If this is a function which returns by invisible reference, the
3922 return value has already been dealt with at the return statements,
3923 so we only need to indirectly copy out the parameters. */
3925 {
3926 tree gnu_ret_deref
3928 tree t;
3933 {
3934 tree gnu_field_deref
3939 }
3940 }
3942 /* Otherwise, if this is a procedure or a function which does not return
3943 by invisible reference, we can do a direct block-copy out. */
3944 else
3945 {
3946 tree gnu_retval;
3950 else
3951 gnu_retval
3953 gnu_cico_list);
3957 }
3961 }
3965 /* Attempt setting the end_locus of our GCC body tree, typically a
3966 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3967 declaration tree. */
3971 /* On SEH targets, install an exception handler around the main entry
3972 point to catch unhandled exceptions. */
3975 {
3976 tree t;
3977 tree etype;
3989 }
3993 /* Finally annotate the parameters and disconnect the trees for parameters
3994 that we have turned into variables since they are now unusable. */
3998 {
4007 }
4009 /* Disconnect the variable created for the return value. */
4013 /* If the function returns an aggregate type and we have candidates for
4014 a Named Return Value, finalize the optimization. */
4016 {
4023 }
4025 /* If this is an inlined external function that has been marked uninlinable,
4026 drop the body and stop there. Otherwise compile the body. */
4029 else
4031 }
4032 \f
4033 /* Return true if GNAT_NODE references an Atomic entity. */
4035 static bool
4037 {
4038 Entity_Id gnat_entity;
4041 {
4057 /* ... fall through ... */
4064 }
4067 }
4069 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. */
4071 static bool
4073 {
4074 Entity_Id gnat_entity;
4077 {
4097 }
4100 }
4102 /* Strip any type conversion on GNAT_NODE and return the result. */
4104 static Node_Id
4106 {
4113 }
4115 /* Return true if GNAT_NODE requires outer atomic access, i.e. atomic access
4116 of an object of which GNAT_NODE is a component. */
4118 static bool
4120 {
4124 {
4126 {
4131 gnat_node
4145 }
4146 }
4149 }
4151 /* Return true if GNAT_NODE requires atomic access and set SYNC according to
4152 the associated synchronization setting. */
4154 static bool
4156 {
4161 /* First, scan the parent to find out cases where the flag is irrelevant. */
4163 {
4166 /* Do not mess up machine code insertions. */
4170 /* Nothing to do if we are the prefix of an attribute, since we do not
4171 want an atomic access for things like 'Size. */
4173 /* ... fall through ... */
4176 /* The N_Reference node is like an attribute. */
4184 /* If we are the prefix, then the access is only partial. */
4190 /* Nothing to do for the identifier in an object renaming declaration,
4191 the renaming itself does not need atomic access. */
4196 }
4198 /* Then, scan the node to find the atomic object. */
4201 /* For Atomic itself, only reads and updates of the object as a whole require
4202 atomic access (RM C.6 (15)). But for Volatile_Full_Access, all reads and
4203 updates require atomic access. */
4208 /* If an outer atomic access will also be required, it cancels this one. */
4215 }
4216 \f
4217 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4219 static tree
4221 {
4222 tree gnu_temp
4228 }
4230 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4231 Put the initialization statement into GNU_INIT_STMT and annotate it with
4232 the SLOC of GNAT_NODE. Return the temporary variable. */
4234 static tree
4236 Node_Id gnat_node)
4237 {
4244 }
4246 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
4247 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4248 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4249 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4250 N_Assignment_Statement and the result is to be placed into that object.
4251 If OUTER_ATOMIC_ACCESS is true, then the assignment to GNU_TARGET must be a
4252 load-modify-store sequence. Otherwise, if ATOMIC_ACCESS is true, then the
4253 assignment to GNU_TARGET must be atomic. If, in addition, ATOMIC_SYNC is
4254 true, then the assignment to GNU_TARGET requires atomic synchronization. */
4256 static tree
4259 {
4262 /* The GCC node corresponding to the GNAT subprogram name. This can either
4263 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4264 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4265 subprogram. */
4267 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4269 /* The return type of the FUNCTION_TYPE. */
4280 Entity_Id gnat_formal;
4281 Node_Id gnat_actual;
4286 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4287 all our args first. */
4289 {
4299 {
4302 }
4305 }
4307 /* For a call to a nested function, check the inlining status. */
4312 /* The only way we can be making a call via an access type is if Name is an
4313 explicit dereference. In that case, get the list of formal args from the
4314 type the access type is pointing to. Otherwise, get the formals from the
4315 entity being called. */
4319 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4321 else
4324 /* The lifetime of the temporaries created for the call ends right after the
4325 return value is copied, so we can give them the scope of the elaboration
4326 routine at top level. */
4328 {
4331 }
4333 /* First, create the temporary for the return value when:
4335 1. There is no target and the function has copy-in/copy-out parameters,
4336 because we need to preserve the return value before copying back the
4337 parameters.
4339 2. There is no target and this is neither an object nor a renaming
4340 declaration, and the return type has variable size, because in
4341 these cases the gimplifier cannot create the temporary.
4343 3. There is a target and it is a slice or an array with fixed size,
4344 and the return type has variable size, because the gimplifier
4345 doesn't handle these cases.
4347 This must be done before we push a binding level around the call, since
4348 we will pop it before copying the return value. */
4351 || (!gnu_target
4355 || (gnu_target
4363 /* Create the list of the actual parameters as GCC expects it, namely a
4364 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4365 is an expression and the TREE_PURPOSE field is null. But skip Out
4366 parameters not passed by reference and that need not be copied in. */
4371 {
4376 const bool is_true_formal_parm
4378 const bool is_by_ref_formal_parm
4379 = is_true_formal_parm
4382 /* In the Out or In Out case, we must suppress conversions that yield
4383 an lvalue but can nevertheless cause the creation of a temporary,
4384 because we need the real object in this case, either to pass its
4385 address if it's passed by reference or as target of the back copy
4386 done after the call if it uses the copy-in/copy-out mechanism.
4387 We do it in the In case too, except for an unchecked conversion
4388 to an elementary type or a constrained composite type because it
4389 alone can cause the actual to be misaligned and the addressability
4390 test is applied to the real object. */
4391 const bool suppress_type_conversion
4398 Node_Id gnat_name = suppress_type_conversion
4401 tree gnu_actual;
4403 /* If it's possible we may need to use this expression twice, make sure
4404 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4405 to force side-effects before the call. */
4407 && !is_by_ref_formal_parm
4409 {
4413 gnu_name
4415 }
4417 /* If we are passing a non-addressable parameter by reference, pass the
4418 address of a copy. In the Out or In Out case, set up to copy back
4419 out after the call. */
4423 {
4427 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4428 but sort of an instantiation for them. */
4430 ;
4432 /* If the type is passed by reference, a copy is not allowed. */
4435 gnat_actual);
4437 /* For users of Starlet we issue a warning because the interface
4438 apparently assumes that by-ref parameters outlive the procedure
4439 invocation. The code still will not work as intended, but we
4440 cannot do much better since low-level parts of the back-end
4441 would allocate temporaries at will because of the misalignment
4442 if we did not do so here. */
4444 {
4445 post_error
4447 post_error_ne
4451 gnat_formal);
4452 }
4454 /* If the actual type of the object is already the nominal type,
4455 we have nothing to do, except if the size is self-referential
4456 in which case we'll remove the unpadding below. */
4459 ;
4461 /* Otherwise remove the unpadding from all the objects. */
4463 && TYPE_IS_PADDING_P
4467 /* Otherwise convert to the nominal type of the object if needed.
4468 There are several cases in which we need to make the temporary
4469 using this type instead of the actual type of the object when
4470 they are distinct, because the expectations of the callee would
4471 otherwise not be met:
4472 - if it's a justified modular type,
4473 - if the actual type is a smaller form of it,
4474 - if it's a smaller form of the actual type. */
4478 gnu_name_type)))
4484 /* If this is an In Out or Out parameter and we're returning a value,
4485 we need to create a temporary for the return value because we must
4486 preserve it before copying back at the very end. */
4490 /* If we haven't pushed a binding level, push a new one. This will
4491 narrow the lifetime of the temporary we are about to make as much
4492 as possible. The drawback is that we'd need to create a temporary
4493 for the return value, if any (see comment before the loop). So do
4494 it only when this temporary was already created just above. */
4496 {
4500 }
4502 /* Create an explicit temporary holding the copy. */
4503 gnu_temp
4506 /* But initialize it on the fly like for an implicit temporary as
4507 we aren't necessarily having a statement list. */
4509 gnu_temp);
4511 /* Set up to move the copy back to the original if needed. */
4513 {
4514 /* If the original is a COND_EXPR whose first arm isn't meant to
4515 be further used, just deal with the second arm. This is very
4516 likely the conditional expression built for a check. */
4519 && integer_zerop
4523 gnu_stmt
4528 }
4529 }
4531 /* Start from the real object and build the actual. */
4534 /* If atomic access is required for an In or In Out actual parameter,
4535 build the atomic load. */
4537 && !is_by_ref_formal_parm
4542 /* If this was a procedure call, we may not have removed any padding.
4543 So do it here for the part we will use as an input, if any. */
4546 gnu_actual
4549 /* Put back the conversion we suppressed above in the computation of the
4550 real object. And even if we didn't suppress any conversion there, we
4551 may have suppressed a conversion to the Etype of the actual earlier,
4552 since the parent is a procedure call, so put it back here. */
4555 gnu_actual
4558 else
4559 gnu_actual
4562 /* Make sure that the actual is in range of the formal's type. */
4565 gnu_actual
4568 /* Unless this is an In parameter, we must remove any justified modular
4569 building from GNU_NAME to get an lvalue. */
4574 gnu_name
4577 /* First see if the parameter is passed by reference. */
4579 {
4581 {
4582 /* In Out or Out parameters passed by reference don't use the
4583 copy-in/copy-out mechanism so the address of the real object
4584 must be passed to the function. */
4587 /* If we have a padded type, be sure we've removed padding. */
4590 gnu_actual);
4592 /* If we have the constructed subtype of an aliased object
4593 with an unconstrained nominal subtype, the type of the
4594 actual includes the template, although it is formally
4595 constrained. So we need to convert it back to the real
4596 constructed subtype to retrieve the constrained part
4597 and takes its address. */
4603 gnu_actual);
4604 }
4606 /* There is no need to convert the actual to the formal's type before
4607 taking its address. The only exception is for unconstrained array
4608 types because of the way we build fat pointers. */
4610 {
4611 /* Put back a view conversion for In Out or Out parameters. */
4614 gnu_actual);
4616 }
4618 /* The symmetry of the paths to the type of an entity is broken here
4619 since arguments don't know that they will be passed by ref. */
4622 }
4624 /* Then see if the parameter is an array passed to a foreign convention
4625 subprogram. */
4627 {
4633 {
4636 }
4638 /* Take the address of the object and convert to the proper pointer
4639 type. We'd like to actually compute the address of the beginning
4640 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4641 possibility that the ARRAY_REF might return a constant and we'd be
4642 getting the wrong address. Neither approach is exactly correct,
4643 but this is the most likely to work in all cases. */
4645 }
4647 /* Otherwise the parameter is passed by copy. */
4648 else
4649 {
4650 tree gnu_size;
4655 /* If we didn't create a PARM_DECL for the formal, this means that
4656 it is an Out parameter not passed by reference and that need not
4657 be copied in. In this case, the value of the actual need not be
4658 read. However, we still need to make sure that its side-effects
4659 are evaluated before the call, so we evaluate its address. */
4661 {
4663 {
4666 }
4668 }
4672 /* If this is 'Null_Parameter, pass a zero even though we are
4673 dereferencing it. */
4679 gnu_actual
4683 integer_zero_node),
4685 else
4687 }
4690 }
4692 gnu_call
4696 /* If we have created a temporary for the return value, initialize it. */
4698 {
4699 tree gnu_stmt
4704 }
4706 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4707 unpack the valued returned from the function into the In Out or Out
4708 parameters. We deal with the function return (if this is an Ada
4709 function) below. */
4711 {
4712 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4713 copy-out parameters. */
4717 /* The call sequence must contain one and only one call, even though the
4718 function is pure. Save the result into a temporary if needed. */
4720 {
4722 {
4723 tree gnu_stmt;
4724 /* If we haven't pushed a binding level, push a new one. This
4725 will narrow the lifetime of the temporary we are about to
4726 make as much as possible. */
4728 {
4732 }
4733 gnu_call
4736 }
4739 }
4741 /* The first entry is for the actual return value if this is a
4742 function, so skip it. */
4748 else
4755 /* If we are dealing with a copy-in/copy-out parameter, we must
4756 retrieve its value from the record returned in the call. */
4762 {
4763 /* Get the value to assign to this Out or In Out parameter. It is
4764 either the result of the function if there is only a single such
4765 parameter or the appropriate field from the record returned. */
4766 tree gnu_result
4768 ? gnu_call
4772 /* If the actual is a conversion, get the inner expression, which
4773 will be the real destination, and convert the result to the
4774 type of the actual parameter. */
4775 tree gnu_actual
4778 /* If the result is a padded type, remove the padding. */
4780 gnu_result
4782 gnu_result);
4784 /* If the actual is a type conversion, the real target object is
4785 denoted by the inner Expression and we need to convert the
4786 result to the associated type.
4787 We also need to convert our gnu assignment target to this type
4788 if the corresponding GNU_NAME was constructed from the GNAT
4789 conversion node and not from the inner Expression. */
4791 {
4792 gnu_result
4793 = convert_with_check
4801 }
4803 /* Unchecked conversions as actuals for Out parameters are not
4804 allowed in user code because they are not variables, but do
4805 occur in front-end expansions. The associated GNU_NAME is
4806 always obtained from the inner expression in such cases. */
4809 gnu_result,
4811 else
4812 {
4814 gnu_result
4816 gnat_actual);
4821 }
4823 /* If an outer atomic access is required for an actual parameter,
4824 build the load-modify-store sequence. */
4826 gnu_result
4829 /* Or else, if simple atomic access is required, build the atomic
4830 store. */
4834 /* Otherwise build a regular assignment. */
4835 else
4844 }
4845 }
4847 /* If this is a function call, the result is the call expression unless a
4848 target is specified, in which case we copy the result into the target
4849 and return the assignment statement. */
4851 {
4852 /* If this is a function with copy-in/copy-out parameters, extract the
4853 return value from it and update the return type. */
4855 {
4857 gnu_call
4860 }
4862 /* If the function returns an unconstrained array or by direct reference,
4863 we have to dereference the pointer. */
4869 {
4873 /* If range check is needed, emit code to generate it. */
4875 gnu_call
4877 gnat_parent);
4879 /* ??? If the return type has variable size, then force the return
4880 slot optimization as we would not be able to create a temporary.
4881 That's what has been done historically. */
4884 else
4887 /* Use the required method to move the result to the target. */
4889 gnu_call
4893 else
4894 gnu_call
4900 }
4901 else
4903 }
4905 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4906 parameters, the result is just the call statement. */
4910 /* Finally, add the copy back statements, if any. */
4916 /* If we have pushed a binding level, pop it and finish up the enclosing
4917 statement group. */
4919 {
4923 }
4925 /* Otherwise, retrieve the statement list, if any. */
4929 /* Otherwise, just return the call expression. */
4930 else
4933 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4934 But first simplify if we have only one statement in the list. */
4936 {
4940 gnu_result
4942 }
4945 }
4946 \f
4947 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4948 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4950 static tree
4952 {
4955 /* If just annotating, ignore all EH and cleanups. */
4959 bool fe_sjlj
4965 tree gnu_result;
4966 tree gnu_expr;
4967 Node_Id gnat_temp;
4968 /* Node providing the sloc for the cleanup actions. */
4971 gnat_node);
4973 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4974 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4975 add_cleanup, and when we leave the binding, end_stmt_group will create
4976 the TRY_FINALLY_EXPR.
4978 ??? The region level calls down there have been specifically put in place
4979 for a ZCX context and currently the order in which things are emitted
4980 (region/handlers) is different from the SJLJ case. Instead of putting
4981 other calls with different conditions at other places for the SJLJ case,
4982 it seems cleaner to reorder things for the SJLJ case and generalize the
4983 condition to make it not ZCX specific.
4985 If there are any exceptions or cleanup processing involved, we need an
4986 outer statement group (for Fe_Sjlj) and binding level. */
4988 {
4991 }
4993 /* If using fe_sjlj, make the variables for the setjmp buffer and save
4994 area for address of previous buffer. Do this first since we need to have
4995 the setjmp buf known for any decls in this block. */
4997 {
4998 gnu_jmpsave_decl
5000 jmpbuf_ptr_type,
5005 /* The __builtin_setjmp receivers will immediately reinstall it. Now
5006 because of the unstructured form of EH used by fe_sjlj, there
5007 might be forward edges going to __builtin_setjmp receivers on which
5008 it is uninitialized, although they will never be actually taken. */
5010 gnu_jmpbuf_decl
5012 jmpbuf_type,
5013 NULL_TREE,
5019 /* When we exit this block, restore the saved value. */
5021 gnat_cleanup_loc_node);
5022 }
5024 /* If we are to call a function when exiting this block, add a cleanup
5025 to the binding level we made above. Note that add_cleanup is FIFO
5026 so we must register this cleanup after the EH cleanup just above. */
5028 {
5030 /* When not optimizing, disable inlining of finalizers as this can
5031 create a more complex CFG in the parent function. */
5035 }
5037 /* Now build the tree for the declarations and statements inside this block.
5038 If this is SJLJ, set our jmp_buf as the current buffer. */
5042 {
5045 gnu_jmpbuf_decl));
5048 }
5054 /* Generate code for each statement in the block. */
5062 /* Now generate code for the two exception models, if either is relevant for
5063 this block. */
5065 {
5067 tree gnu_handler;
5069 /* Make a binding level for the exception handling declarations and code
5070 and set up gnu_except_ptr_stack for the handlers to use. */
5081 /* Generate code for each handler. The N_Exception_Handler case does the
5082 real work and returns a COND_EXPR for each handler, which we chain
5083 together here. */
5086 {
5089 /* If this is the first one, set it as the outer one. Otherwise,
5090 point the "else" part of the previous handler to us. Then point
5091 to our "else" part. */
5094 else
5098 }
5100 /* If none of the exception handlers did anything, re-raise but do not
5101 defer abortion. */
5104 set_expr_location_from_node
5110 else
5113 /* End the binding level dedicated to the exception handlers and get the
5114 whole statement group. */
5119 /* If the setjmp returns 1, we restore our incoming longjmp value and
5120 then check the handlers. */
5123 gnu_jmpsave_decl),
5124 gnat_node);
5128 /* This block is now "if (setjmp) ... <handlers> else <block>". */
5130 (build_call_n_expr
5133 gnu_jmpbuf_decl))),
5135 }
5137 {
5138 tree gnu_handlers;
5139 location_t locus;
5141 /* First make a block containing the handlers. */
5149 /* Now make the TRY_CATCH_EXPR for the block. */
5152 /* Set a location. We need to find a unique location for the dispatching
5153 code, otherwise we can get coverage or debugging issues. Try with
5154 the location of the end label. */
5158 else
5159 /* Clear column information so that the exception handler of an
5160 implicit transient block does not incorrectly inherit the slocs
5161 of a decision, which would otherwise confuse control flow based
5162 coverage analysis tools. */
5164 }
5165 else
5168 /* Now close our outer block, if we had to make one. */
5170 {
5174 }
5177 }
5178 \f
5179 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5180 to a GCC tree, which is returned. This is the variant for front-end sjlj
5181 exception handling. */
5183 static tree
5185 {
5186 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
5187 an "if" statement to select the proper exceptions. For "Others", exclude
5188 exceptions where Handled_By_Others is nonzero unless the All_Others flag
5189 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
5192 Node_Id gnat_temp;
5196 {
5197 tree this_choice;
5200 {
5203 else
5204 this_choice
5205 = build_binary_op
5207 convert
5209 build_component_ref
5210 (build_unary_op
5213 not_handled_by_others_decl,
5215 integer_zero_node);
5216 }
5220 {
5222 tree gnu_expr;
5224 /* Exception may be a renaming. Recover original exception which is
5225 the one elaborated and registered. */
5231 this_choice
5232 = build_binary_op
5237 }
5238 else
5243 }
5246 }
5247 \f
5248 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5249 to a GCC tree, which is returned. This is the variant for GCC exception
5250 schemes. */
5252 static tree
5254 {
5257 Node_Id gnat_temp;
5259 /* We build a TREE_LIST of nodes representing what exception types this
5260 handler can catch, with special cases for others and all others cases.
5262 Each exception type is actually identified by a pointer to the exception
5263 id, or to a dummy object for "others" and "all others". */
5266 {
5270 {
5273 }
5276 {
5279 /* Exception may be a renaming. Recover original exception which is
5280 the one elaborated and registered. */
5286 }
5287 else
5290 /* The GCC interface expects NULL to be passed for catch all handlers, so
5291 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5292 is integer_zero_node. It would not work, however, because GCC's
5293 notion of "catch all" is stronger than our notion of "others". Until
5294 we correctly use the cleanup interface as well, doing that would
5295 prevent the "all others" handlers from being seen, because nothing
5296 can be caught beyond a catch all from GCC's point of view. */
5298 }
5303 /* Expand a call to the begin_handler hook at the beginning of the handler,
5304 and arrange for a call to the end_handler hook to occur on every possible
5305 exit path.
5307 The hooks expect a pointer to the low level occurrence. This is required
5308 for our stack management scheme because a raise inside the handler pushes
5309 a new occurrence on top of the stack, which means that this top does not
5310 necessarily match the occurrence this handler was dealing with.
5312 __builtin_eh_pointer references the exception occurrence being
5313 propagated. Upon handler entry, this is the exception for which the
5314 handler is triggered. This might not be the case upon handler exit,
5315 however, as we might have a new occurrence propagated by the handler's
5316 body, and the end_handler hook called as a cleanup in this context.
5318 We use a local variable to retrieve the incoming value at handler entry
5319 time, and reuse it to feed the end_handler hook's argument at exit. */
5321 gnu_current_exc_ptr
5325 gnu_incoming_exc_ptr
5332 gnu_incoming_exc_ptr),
5333 gnat_node);
5335 /* Declare and initialize the choice parameter, if present. */
5337 {
5338 tree gnu_param
5344 gnu_incoming_exc_ptr));
5345 }
5347 /* We don't have an End_Label at hand to set the location of the cleanup
5348 actions, so we use that of the exception handler itself instead. */
5350 gnat_node);
5356 return
5358 }
5359 \f
5360 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5362 static void
5364 {
5369 Entity_Id gnat_entity;
5370 Node_Id gnat_pragma;
5371 /* Make the decl for the elaboration procedure. */
5372 tree gnu_elab_proc_decl
5373 = create_subprog_decl
5383 /* Initialize the information structure for the function. */
5392 /* For a body, first process the spec if there is one. */
5398 {
5405 }
5407 /* Then process any pragmas and declarations preceding the unit. */
5416 /* Process the unit itself. */
5419 /* Generate code for all the inlined subprograms. */
5423 {
5424 Node_Id gnat_body;
5426 /* Without optimization, process only the required subprograms. */
5432 {
5433 /* ??? This happens when only the spec of a package is provided. */
5437 gnat_body
5439 }
5441 /* Define the entity first so we set DECL_EXTERNAL. */
5444 }
5446 /* Process any pragmas and actions following the unit. */
5451 /* Save away what we've made so far and finish it up. */
5458 /* Record this potential elaboration procedure for later processing. */
5465 /* Force the processing for all nodes that remain in the queue. */
5467 }
5468 \f
5469 /* Mark COND, a boolean expression, as predicating a call to a noreturn
5470 function, i.e. predict that it is very likely false, and return it.
5472 The compiler will automatically predict the last edge leading to a call
5473 to a noreturn function as very unlikely taken. This function makes it
5474 possible to expand the prediction to predecessors in case the condition
5475 is made up of several short-circuit operators. */
5477 static tree
5479 {
5489 PRED_NORETURN));
5492 }
5494 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5495 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5496 we should place the result type. LABEL_P is true if there is a label to
5497 branch to for the exception. */
5499 static tree
5501 {
5505 const bool with_extra_info
5506 = Exception_Extra_Info
5514 {
5524 {
5531 {
5551 }
5558 && gnu_low_bound
5559 && gnu_high_bound
5562 gnu_result
5566 /* If optimization is enabled and we are inside a loop, we try to
5567 compute invariant conditions for checks applied to the iteration
5568 variable, i.e. conditions that are independent of the variable
5569 and necessary in order for the checks to fail in the course of
5570 some iteration. If we succeed, we consider an alternative:
5572 1. If loop unswitching is enabled, we prepend these conditions
5573 to the original conditions of the checks. This will make it
5574 possible for the loop unswitching pass to replace the loop
5575 with two loops, one of which has the checks eliminated and
5576 the other has the original checks reinstated, and a prologue
5577 implementing a run-time selection. The former loop will be
5578 for example suitable for vectorization.
5580 2. Otherwise, we instead append the conditions to the original
5581 conditions of the checks. At worse, if the conditions cannot
5582 be evaluated at compile time, they will be evaluated as true
5583 at run time only when the checks have already failed, thus
5584 contributing negatively only to the size of the executable.
5585 But the hope is that these invariant conditions be evaluated
5586 at compile time to false, thus taking away the entire checks
5587 with them. */
5590 && (!gnu_low_bound
5592 && (!gnu_high_bound
5595 {
5602 rci->inserted_cond
5609 boolean_type_node,
5611 gnu_cond);
5612 else
5614 boolean_type_node,
5615 gnu_cond,
5617 }
5619 /* Or else, if aggressive loop optimizations are enabled, we just
5620 record that there are checks applied to iteration variables. */
5622 && flag_aggressive_loop_optimizations
5626 }
5631 }
5633 common:
5638 /* If the type is VOID, this is a statement, so we need to generate the code
5639 for the call. Handle a condition, if there is one. */
5641 {
5643 {
5648 }
5649 }
5650 else
5654 }
5655 \f
5656 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5657 parameter of a call. */
5659 static bool
5661 {
5676 }
5678 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5679 of an assignment or an actual parameter of a call. */
5681 static bool
5683 {
5684 Node_Kind kind;
5696 }
5698 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5699 as gigi is concerned. This is used to avoid conversions on the LHS. */
5701 static bool
5703 {
5706 /* The conversion must be on the LHS of an assignment or an actual parameter
5707 of a call. Otherwise, even if the conversion was essentially a no-op, it
5708 could de facto ensure type consistency and this should be preserved. */
5714 /* We're interested in artificial conversions generated by the front-end
5715 to make private types explicit, e.g. in Expand_Assign_Array. */
5722 /* The direct conversion to the underlying type is a no-op. */
5726 /* For an array subtype, the conversion to the PAIT is a no-op. */
5731 /* For a record subtype, the conversion to the type is a no-op. */
5737 }
5739 /* This function is the driver of the GNAT to GCC tree transformation process.
5740 It is the entry point of the tree transformer. GNAT_NODE is the root of
5741 some GNAT tree. Return the root of the corresponding GCC tree. If this
5742 is an expression, return the GCC equivalent of the expression. If this
5743 is a statement, return the statement or add it to the current statement
5744 group, in which case anything returned is to be interpreted as occurring
5745 after anything added. */
5747 tree
5749 {
5755 Node_Id gnat_temp;
5758 /* Save node number for error message and set location information. */
5762 /* If this node is a statement and we are only annotating types, return an
5763 empty statement list. */
5767 /* If this node is a non-static subexpression and we are only annotating
5768 types, make this into a NULL_EXPR. */
5776 N_Raise_Constraint_Error));
5785 {
5788 /* If this is a statement and we are at top level, it must be part of
5789 the elaboration procedure, so mark us as being in that procedure. */
5791 {
5794 }
5796 /* If we are in the elaboration procedure, check if we are violating a
5797 No_Elaboration_Code restriction by having a statement there. Don't
5798 check for a possible No_Elaboration_Code restriction violation on
5799 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5800 every nested real statement instead. This also avoids triggering
5801 spurious errors on dummy (empty) sequences created by the front-end
5802 for package bodies in some cases. */
5806 }
5809 {
5810 /********************************/
5811 /* Chapter 2: Lexical Elements */
5812 /********************************/
5821 /* If atomic access is required on the RHS, build the atomic load. */
5828 {
5829 tree gnu_type;
5831 /* Get the type of the result, looking inside any padding and
5832 justified modular types. Then get the value in that type. */
5841 /* If the result overflows (meaning it doesn't fit in its base type),
5842 abort. We would like to check that the value is within the range
5843 of the subtype, but that causes problems with subtypes whose usage
5844 will raise Constraint_Error and with biased representation, so
5845 we don't. */
5847 }
5851 /* If a Entity is present, it means that this was one of the
5852 literals in a user-defined character type. In that case,
5853 just return the value in the CONST_DECL. Otherwise, use the
5854 character code. In that case, the base type should be an
5855 INTEGER_TYPE, but we won't bother checking for that. */
5859 else
5860 gnu_result
5861 = build_int_cst_type
5868 /* If this is of a fixed-point type, the value we want is the value of
5869 the corresponding integer. */
5871 {
5873 gnu_result_type);
5875 }
5877 else
5878 {
5881 /* First convert the value to a machine number if it isn't already.
5882 That will force the base to 2 for non-zero values and simplify
5883 the rest of the logic. */
5885 ur_realval
5891 else
5892 {
5893 REAL_VALUE_TYPE tmp;
5897 /* The base must be 2 as Machine guarantees this, so we scale
5898 the value, which we know can fit in the mantissa of the type
5899 (hence the use of that type above). */
5904 }
5906 /* Now see if we need to negate the result. Do it this way to
5907 properly handle -0. */
5909 gnu_result
5911 gnu_result);
5912 }
5919 {
5926 else
5929 /* Build the string with the characters in the literal. Note
5930 that Ada strings are 1-origin. */
5934 /* Put a null at the end of the string in case it's in a context
5935 where GCC will want to treat it as a C string. */
5940 /* Strings in GCC don't normally have types, but we want
5941 this to not be converted to the array type. */
5946 }
5947 else
5948 {
5949 /* Build a list consisting of each character, then make
5950 the aggregate. */
5960 {
5966 }
5969 }
5976 /**************************************/
5977 /* Chapter 3: Declarations and Types */
5978 /**************************************/
5995 /* If we are just annotating types and this object has an unconstrained
5996 or task type, don't elaborate it. */
6006 && (!type_annotate_only
6008 {
6011 gnu_expr
6016 }
6017 else
6020 /* If this is a deferred constant with an address clause, we ignore the
6021 full view since the clause is on the partial view and we cannot have
6022 2 different GCC trees for the object. The only bits of the full view
6023 we will use is the initializer, but it will be directly fetched. */
6029 /* If this object has its elaboration delayed, we must force evaluation
6030 of GNU_EXPR now and save it for the freeze point. Note that we need
6031 not do anything special at the global level since the lifetime of the
6032 temporary is fully contained within the elaboration routine. */
6034 {
6036 {
6039 }
6040 }
6041 else
6049 /* Don't do anything if this renaming is handled by the front end or if
6050 we are just annotating types and this object has a composite or task
6051 type, don't elaborate it. */
6053 && ! (type_annotate_only
6057 {
6058 tree gnu_temp
6061 /* See case 2 of renaming in gnat_to_gnu_entity. */
6064 }
6071 /* See the above case for the rationale. */
6073 {
6074 tree gnu_temp
6079 }
6083 {
6089 /* Materializing renamed subprograms will only benefit the debugging
6090 information as they aren't referenced in the generated code. So
6091 skip them when they aren't needed. Avoid doing this if:
6093 - there is a freeze node: in this case the renamed entity is not
6094 elaborated yet,
6095 - the renamed subprogram is intrinsic: it will not be available in
6096 the debugging information (note that both or only one of the
6097 renaming and the renamed subprograms can be intrinsic). */
6108 }
6117 /* These are fully handled in the front end. */
6118 /* ??? For package renamings, find a way to use GENERIC namespaces so
6119 that we get proper debug information for them. */
6123 /*************************************/
6124 /* Chapter 4: Names and Expressions */
6125 /*************************************/
6132 /* If atomic access is required on the RHS, build the atomic load. */
6139 {
6141 tree gnu_type;
6148 /* Convert vector inputs to their representative array type, to fit
6149 what the code below expects. */
6151 {
6155 }
6159 /* If we got a padded type, remove it too. */
6161 gnu_array_object
6163 gnu_array_object);
6167 /* The failure of this assertion will very likely come from a missing
6168 expansion for a packed array access. */
6171 /* First compute the number of dimensions of the array, then
6172 fill the expression array, the order depending on whether
6173 this is a Convention_Fortran array or not. */
6178 ;
6187 else
6196 {
6203 gnu_expr
6204 = emit_index_check
6208 gnat_temp);
6210 gnu_result
6213 /* Array accesses are bound-checked so they cannot trap, but this
6214 is valid only if they are not hoisted ahead of the check. We
6215 need to mark them as no-trap to get decent loop optimizations
6216 in the presence of -fnon-call-exceptions, so we do it when we
6217 know that the original expression had no side-effects. */
6223 /* If aggressive loop optimizations are enabled, we warn for loops
6224 overrunning a simple array of size 1 not at the end of a record.
6225 This is aimed to catch misuses of the trailing array idiom. */
6227 && flag_aggressive_loop_optimizations
6243 {
6246 }
6247 }
6251 /* If atomic access is required on the RHS, build the atomic load. */
6255 }
6259 {
6261 tree gnu_type;
6266 /* Do any implicit dereferences of the prefix and do any needed
6267 range check. */
6272 {
6273 /* Get the bounds of the slice. */
6274 tree gnu_index_type
6278 /* Get the permitted bounds. */
6279 tree gnu_base_index_type
6281 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
6283 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
6290 /* Derive a good type to convert everything to. */
6293 /* Test whether the minimum slice value is too small. */
6296 gnu_min_expr),
6298 gnu_base_min_expr));
6300 /* Test whether the maximum slice value is too large. */
6303 gnu_max_expr),
6305 gnu_base_max_expr));
6307 /* Build a slice index check that returns the low bound,
6308 assuming the slice is not empty. */
6309 gnu_expr = emit_check
6314 /* Build a conditional expression that does the index checks and
6315 returns the low bound if the slice is not empty (max >= min),
6316 and returns the naked low bound otherwise (max < min), unless
6317 it is non-constant and the high bound is; this prevents VRP
6318 from inferring bogus ranges on the unlikely path. */
6322 gnu_max_expr),
6324 gnu_min_expr)),
6325 gnu_expr,
6329 }
6330 else
6331 /* Simply return the naked low bound. */
6334 /* If this is a slice with non-constant size of an array with constant
6335 size, set the maximum size for the allocation of temporaries. */
6342 }
6346 {
6350 tree gnu_field;
6354 /* For discriminant references in tagged types always substitute the
6355 corresponding discriminant as the actual selected component. */
6360 /* For discriminant references of untagged types always substitute the
6361 corresponding stored discriminant. */
6365 /* Handle extracting the real or imaginary part of a complex.
6366 The real part is the first field and the imaginary the last. */
6371 else
6372 {
6375 gnu_result
6379 && lvalue_required_for_attribute_p
6381 }
6385 /* If atomic access is required on the RHS, build the atomic load. */
6389 }
6393 {
6394 /* The attribute designator. */
6397 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6398 is a unit, not an object with a GCC equivalent. */
6400 return
6409 }
6413 /* Like 'Access as far as we are concerned. */
6421 {
6422 tree gnu_aggr_type;
6424 /* ??? It is wrong to evaluate the type now, but there doesn't
6425 seem to be any other practical way of doing it. */
6429 gnu_aggr_type = gnu_result_type
6434 gnu_aggr_type
6441 NULL);
6445 gnu_result
6448 gnu_aggr_type);
6451 gnu_aggr_type,
6454 gnu_result
6455 = build_binary_op
6460 (Next
6462 else
6466 }
6474 else
6481 /* Get the operand expression. */
6485 /* If this is a qualified expression for a tagged type, we mark the type
6486 as used. Because of polymorphism, this might be the only reference to
6487 the tagged type in the program while objects have it as dynamic type.
6488 The debugger needs to see it to display these objects properly. */
6492 gnu_result
6496 kind == N_Type_Conversion
6503 /* Skip further processing if the conversion is deemed a no-op. */
6505 {
6508 }
6512 /* If the result is a pointer type, see if we are improperly
6513 converting to a stricter alignment. */
6516 {
6522 post_error_ne_tree_2
6526 }
6528 /* If we are converting a descriptor to a function pointer, first
6529 build the pointer. */
6541 {
6546 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6547 subtype. */
6549 {
6552 }
6555 {
6559 gnu_low
6561 gnu_high
6563 }
6564 else
6569 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6570 ensure that GNU_OBJ is evaluated only once and perform a full range
6571 test. */
6573 gnu_result
6575 else
6576 {
6585 gnu_result
6587 }
6590 gnu_result
6592 }
6600 ? RDIV_EXPR
6607 /* These can either be operations on booleans or on modular types.
6608 Fall through for boolean types since that's the way GNU_CODES is
6609 set up. */
6611 {
6612 enum tree_code code
6623 }
6625 /* ... fall through ... */
6637 {
6641 tree gnu_type;
6647 /* Pending generic support for efficient vector logical operations in
6648 GCC, convert vectors to their representative array type view and
6649 fallthrough. */
6653 /* If this is a comparison operator, convert any references to an
6654 unconstrained array value into a reference to the actual array. */
6656 {
6659 }
6661 /* If this is a shift whose count is not guaranteed to be correct,
6662 we need to adjust the shift count. */
6664 {
6666 tree gnu_max_shift
6673 gnu_rhs
6674 = build_binary_op
6677 gnu_count_type,
6678 gnu_max_shift,
6680 integer_one_node)),
6681 gnu_rhs);
6682 }
6684 /* For right shifts, the type says what kind of shift to do,
6685 so we may need to choose a different type. In this case,
6686 we have to ignore integer overflow lest it propagates all
6687 the way down and causes a CE to be explicitly raised. */
6689 {
6692 }
6695 {
6698 }
6701 {
6707 }
6709 /* Instead of expanding overflow checks for addition, subtraction
6710 and multiplication itself, the front end will leave this to
6711 the back end when Backend_Overflow_Checks_On_Target is set.
6712 As the GCC back end itself does not know yet how to properly
6713 do overflow checking, do it here. The goal is to push
6714 the expansions further into the back end over time. */
6723 else
6724 {
6725 /* Some operations, e.g. comparisons of arrays, generate complex
6726 trees that need to be annotated while they are being built. */
6729 }
6731 /* If this is a logical shift with the shift count not verified,
6732 we must return zero if it is too large. We cannot compensate
6733 above in this case. */
6736 gnu_result
6737 = build_cond_expr
6740 gnu_rhs,
6744 gnu_result);
6745 }
6749 {
6752 tree gnu_false
6756 gnu_result
6758 }
6767 /* This case can apply to a boolean or a modular type.
6768 Fall through for a boolean operand since GNU_CODES is set
6769 up to handle this. */
6771 {
6775 gnu_expr);
6777 }
6779 /* ... fall through ... */
6788 gnu_result
6791 else
6797 {
6799 tree gnu_type;
6804 /* The Expression operand can either be an N_Identifier or
6805 Expanded_Name, which must represent a type, or a
6806 N_Qualified_Expression, which contains both the object type and an
6807 initial value for the object. */
6812 {
6813 Entity_Id gnat_desig_type
6821 gnu_init
6827 else
6828 {
6832 }
6834 /* See the N_Qualified_Expression case for the rationale. */
6839 }
6840 else
6847 ignore_init_type);
6848 }
6851 /**************************/
6852 /* Chapter 5: Statements */
6853 /**************************/
6861 /* When not optimizing, turn null statements from source into gotos to
6862 the next statement that the middle-end knows how to preserve. */
6864 {
6875 }
6876 else
6881 /* Get the LHS and RHS of the statement and convert any reference to an
6882 unconstrained array into a reference to the underlying array. */
6885 /* If the type has a size that overflows, convert this into raise of
6886 Storage_Error: execution shouldn't have gotten here anyway. */
6890 N_Raise_Storage_Error);
6892 {
6893 bool outer_atomic_access
6895 bool atomic_access
6896 = !outer_atomic_access
6898 gnu_result
6901 }
6902 else
6903 {
6905 const Entity_Id gnat_type
6907 const bool regular_array_type_p
6909 const bool use_memset_p
6910 = (regular_array_type_p
6914 /* If we'll use memset, we need to find the inner expression. */
6916 {
6917 Node_Id gnat_inner
6921 gnat_inner
6924 }
6925 else
6928 /* If range check is needed, emit code to generate it. */
6931 gnat_node);
6933 /* If an outer atomic access is required on the LHS, build the load-
6934 modify-store sequence. */
6938 /* Or else, if atomic access is required, build the atomic store. */
6942 /* Or else, use memset when the conditions are met. */
6944 {
6948 tree size
6953 {
6954 tree mask
6958 }
6960 }
6962 /* Otherwise build a regular assignment. */
6963 else
6964 gnu_result
6967 /* If the assignment type is a regular array and the two sides are
6968 not completely disjoint, play safe and use memmove. But don't do
6969 it for a bit-packed array as it might not be byte-aligned. */
6971 && regular_array_type_p
6973 {
6977 tree size
6983 }
6984 }
6988 {
6991 /* Make the outer COND_EXPR. Avoid non-determinism. */
7000 /* Now make a COND_EXPR for each of the "else if" parts. Put each
7001 into the previous "else" part and point to where to put any
7002 outer "else". Also avoid non-determinism. */
7006 {
7016 }
7019 }
7031 /* The only way to enter the block is to fall through to it. */
7033 {
7040 }
7041 else
7046 gnu_result
7056 {
7059 /* If the subprogram is a function, we must return the expression. */
7061 {
7064 /* If this function has copy-in/copy-out parameters parameters and
7065 doesn't return by invisible reference, get the real object for
7066 the return. See Subprogram_Body_to_gnu. */
7070 else
7073 /* Get the GCC tree for the expression to be returned. */
7076 /* Do not remove the padding from GNU_RET_VAL if the inner type is
7077 self-referential since we want to allocate the fixed size. */
7079 && type_is_padding_self_referential
7083 /* If the function returns by direct reference, return a pointer
7084 to the return value. */
7089 /* Otherwise, if it returns an unconstrained array, we have to
7090 allocate a new version of the result and return it. */
7092 {
7095 /* And find out whether this is a candidate for Named Return
7096 Value. If so, record it. */
7098 {
7101 /* Strip useless conversions around the return value. */
7105 /* Strip unpadding around the return value. */
7107 && TYPE_IS_PADDING_P
7111 /* Now apply the test to the return value. */
7113 {
7119 }
7120 }
7123 gnu_ret_val,
7128 }
7130 /* Otherwise, if it returns by invisible reference, dereference
7131 the pointer it is passed using the type of the return value
7132 and build the copy operation manually. This ensures that we
7133 don't copy too much data, for example if the return type is
7134 unconstrained with a maximum size. */
7136 {
7137 tree gnu_ret_deref
7139 gnu_ret_obj);
7144 }
7145 }
7147 else
7150 /* If we have a return label defined, convert this into a branch to
7151 that label. The return proper will be handled elsewhere. */
7153 {
7156 gnu_ret_val));
7161 /* When not optimizing, make sure the return is preserved. */
7164 }
7166 /* Otherwise, build a regular return. */
7167 else
7169 }
7173 gnu_result
7177 /***************************/
7178 /* Chapter 6: Subprograms */
7179 /***************************/
7182 /* Unless there is a freeze node, declare the subprogram. We consider
7183 this a "definition" even though we're not generating code for
7184 the subprogram because we will be making the corresponding GCC
7185 node here. */
7194 /* This subprogram doesn't exist for code generation purposes, but we
7195 have to elaborate the types of any parameters and result, unless
7196 they are imported types (nothing to generate in this case).
7198 The parameter list may contain types with freeze nodes, e.g. not null
7199 subtypes, so the subprogram itself may carry a freeze node, in which
7200 case its elaboration must be deferred. */
7202 /* Process the parameter types first. */
7205 = First_Formal_With_Extras
7213 /* Then the result type, set to Standard_Void_Type for procedures. */
7214 {
7215 Entity_Id gnat_temp_type
7220 }
7226 /* For a child unit identifier go up a level to get the specification.
7227 We get this when we try to find the spec of a child unit package
7228 that is the compilation unit being compiled. */
7243 /************************/
7244 /* Chapter 7: Packages */
7245 /************************/
7261 /* If this is the body of a generic package - do nothing. */
7263 {
7266 }
7277 /********************************/
7278 /* Chapter 8: Visibility Rules */
7279 /********************************/
7283 /* Nothing to do here - but these may appear in list of declarations. */
7287 /*********************/
7288 /* Chapter 9: Tasks */
7289 /*********************/
7300 /*********************************************************/
7301 /* Chapter 10: Program Structure and Compilation Issues */
7302 /*********************************************************/
7305 /* This is not called for the main unit on which gigi is invoked. */
7317 /* These nodes should only be present when annotating types. */
7327 /* Simply process whatever unit is being inserted. */
7330 else
7331 {
7334 }
7337 /***************************/
7338 /* Chapter 11: Exceptions */
7339 /***************************/
7342 /* If there is an At_End procedure attached to this node, and the EH
7343 mechanism is front-end, we must have at least a corresponding At_End
7344 handler, unless the No_Exception_Handlers restriction is set. */
7359 else
7364 /* Only for reraise in back-end exceptions mode. */
7371 /* Clear the current exception pointer so that the occurrence won't be
7372 deallocated. */
7412 /******************************/
7413 /* Chapter 12: Generic Units */
7414 /******************************/
7424 /* These nodes can appear on a declaration list but there is nothing to
7425 to be done with them. */
7429 /**************************************************/
7430 /* Chapter 13: Representation Clauses and */
7431 /* Implementation-Dependent Features */
7432 /**************************************************/
7437 /* The only one we need to deal with is 'Address since, for the others,
7438 the front-end puts the information elsewhere. */
7442 /* And we only deal with 'Address if the object has a Freeze node. */
7447 /* Get the value to use as the address and save it as the equivalent
7448 for the object. When it is frozen, gnat_to_gnu_entity will do the
7449 right thing. */
7456 /* We do nothing with these. SEM puts the information elsewhere. */
7462 {
7472 /* First retrieve the 3 operand lists built by the front-end. */
7475 {
7482 }
7486 {
7493 }
7497 gnu_clobbers
7500 gnu_clobbers);
7502 /* Then perform some standard checking and processing on the
7503 operands. In particular, mark them addressable if needed. */
7511 {
7513 constraint
7519 {
7520 /* If the operand is going to end up in memory,
7521 mark it addressable. Note that we don't test
7522 allows_mem like in the input case below; this
7523 is modelled on the C front-end. */
7525 {
7532 }
7533 }
7534 else
7538 }
7541 {
7543 constraint
7549 {
7550 /* If the operand is going to end up in memory,
7551 mark it addressable. */
7553 {
7560 }
7561 }
7562 else
7566 }
7572 }
7573 else
7578 /****************/
7579 /* Added Nodes */
7580 /****************/
7583 /* This construct doesn't define a scope so we don't push a binding
7584 level around the statement list, but we wrap it in a SAVE_EXPR to
7585 protect it from unsharing. Elaborate the expression as part of the
7586 same statement group as the actions so that the type declaration
7587 gets inserted there as well. This ensures that the type elaboration
7588 code is issued past the actions computing values on which it might
7589 depend. */
7598 gnu_result
7623 {
7628 /* If this is a thin pointer, we must first dereference it to create
7629 a fat pointer, then go back below to a thin pointer. The reason
7630 for this is that we need to have a fat pointer someplace in order
7631 to properly compute the size. */
7635 gnu_ptr));
7637 /* If this is a fat pointer, the object must have been allocated with
7638 the template in front of the array. So pass the template address,
7639 and get the total size; do it by converting to a thin pointer. */
7641 gnu_ptr
7643 (TYPE_OBJECT_RECORD_TYPE
7645 gnu_ptr);
7649 /* If this is a thin pointer, the object must have been allocated with
7650 the template in front of the array. So pass the template address,
7651 and get the total size. */
7653 gnu_ptr
7655 gnu_ptr,
7657 byte_position
7658 (DECL_CHAIN
7661 /* If we have a special dynamic constrained subtype on the node, use
7662 it to compute the size; otherwise, use the designated subtype. */
7664 {
7665 gnu_actual_obj_type
7669 gnu_actual_obj_type
7671 gnu_actual_obj_type,
7674 }
7675 else
7678 gnu_result
7681 gnu_obj_type,
7684 gnat_node);
7685 }
7693 else
7698 /* The only validation we currently do on an unchecked conversion is
7699 that of aliasing assumptions. */
7709 /* These nodes should only be present when annotating types. */
7715 /* Other nodes are not supposed to reach here. */
7717 }
7719 /* If we pushed the processing of the elaboration routine, pop it back. */
7723 /* When not optimizing, turn boolean rvalues B into B != false tests
7724 so that the code just below can put the location information of the
7725 reference to B on the inequality operator for better debug info. */
7739 boolean_false_node));
7741 /* Set the location information on the result. Note that we may have
7742 no result if we tried to build a CALL_EXPR node to a procedure with
7743 no side-effects and optimization is enabled. */
7747 /* If we're supposed to return something of void_type, it means we have
7748 something we're elaborating for effect, so just return. */
7752 /* If the result is a constant that overflowed, raise Constraint_Error. */
7754 {
7756 gnu_result
7759 N_Raise_Constraint_Error));
7760 }
7762 /* If the result has side-effects and is of an unconstrained type, make a
7763 SAVE_EXPR so that we can be sure it will only be referenced once. But
7764 this is useless for a call to a function that returns an unconstrained
7765 type with default discriminant, as we cannot compute the size of the
7766 actual returned object. We must do this before any conversions. */
7774 /* Now convert the result to the result type, unless we are in one of the
7775 following cases:
7777 1. If this is the LHS of an assignment or an actual parameter of a
7778 call, return the result almost unmodified since the RHS will have
7779 to be converted to our type in that case, unless the result type
7780 has a simpler size. Likewise if there is just a no-op unchecked
7781 conversion in-between. Similarly, don't convert integral types
7782 that are the operands of an unchecked conversion since we need
7783 to ignore those conversions (for 'Valid).
7785 2. If we have a label (which doesn't have any well-defined type), a
7786 field or an error, return the result almost unmodified. Similarly,
7787 if the two types are record types with the same name, don't convert.
7788 This will be the case when we are converting from a packable version
7789 of a type to its original type and we need those conversions to be
7790 NOPs in order for assignments into these types to work properly.
7792 3. If the type is void or if we have no result, return error_mark_node
7793 to show we have no result.
7795 4. If this is a call to a function that returns with variable size and
7796 the call is used as the expression in either an object or a renaming
7797 declaration, return the result unmodified because we want to use the
7798 return slot optimization in this case.
7800 5. Finally, if the type of the result is already correct. */
7818 && (CONTAINS_PLACEHOLDER_P
7822 {
7823 /* Remove padding only if the inner object is of self-referential
7824 size: in that case it must be an object of unconstrained type
7825 with a default discriminant and we want to avoid copying too
7826 much data. */
7829 gnu_result);
7830 }
7839 {
7840 /* Remove any padding. */
7843 gnu_result);
7844 }
7854 ;
7859 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7866 }
7867 \f
7868 /* Subroutine of above to push the exception label stack. GNU_STACK is
7869 a pointer to the stack to update and GNAT_LABEL, if present, is the
7870 label to push onto the stack. */
7872 static void
7874 {
7880 }
7881 \f
7882 /* Record the current code position in GNAT_NODE. */
7884 static void
7886 {
7891 }
7893 /* Insert the code for GNAT_NODE at the position saved for that node. */
7895 static void
7897 {
7900 }
7901 \f
7902 /* Start a new statement group chained to the previous group. */
7904 void
7906 {
7909 /* First see if we can get one from the free list. */
7912 else
7918 }
7920 /* Add GNU_STMT to the current statement group. If it is an expression with
7921 no effects, it is ignored. */
7923 void
7925 {
7927 }
7929 /* Similar, but the statement is always added, regardless of side-effects. */
7931 void
7933 {
7935 }
7937 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7939 void
7941 {
7942 /* Do not emit a location for renamings that come from generic instantiation,
7943 they are likely to disturb debugging. */
7948 }
7950 /* Similar, but the statement is always added, regardless of side-effects. */
7952 void
7954 {
7958 }
7960 /* Add a declaration statement for GNU_DECL to the current statement group.
7961 Get SLOC from Entity_Id. */
7963 void
7965 {
7969 /* If this is a variable that Gigi is to ignore, we may have been given
7970 an ERROR_MARK. So test for it. We also might have been given a
7971 reference for a renaming. So only do something for a decl. Also
7972 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7980 /* If we are external or global, we don't want to output the DECL_EXPR for
7981 this DECL node since we already have evaluated the expressions in the
7982 sizes and positions as globals and doing it again would be wrong. */
7984 {
7985 /* Mark everything as used to prevent node sharing with subprograms.
7986 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7987 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7991 {
7995 }
7996 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
8001 }
8002 else
8005 /* If this is a variable and an initializer is attached to it, it must be
8006 valid for the context. Similar to init_const in create_var_decl. */
8013 {
8014 /* If GNU_DECL has a padded type, convert it to the unpadded
8015 type so the assignment is done properly. */
8018 else
8025 {
8028 }
8031 }
8032 }
8034 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
8036 static tree
8038 {
8044 /* Don't mark a dummy type as visited because we want to mark its sizes
8045 and fields once it's filled in. */
8053 }
8055 /* Mark nodes rooted at T with TREE_VISITED and types as having their
8056 sized gimplified. We use this to indicate all variable sizes and
8057 positions in global types may not be shared by any subprogram. */
8059 void
8061 {
8063 }
8065 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
8066 set its location to that of GNAT_NODE if present, but with column info
8067 cleared so that conditional branches generated as part of the cleanup
8068 code do not interfere with coverage analysis tools. */
8070 static void
8072 {
8076 }
8078 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
8080 void
8082 {
8085 }
8087 /* Return code corresponding to the current code group. It is normally
8088 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
8089 BLOCK or cleanups were set. */
8091 tree
8093 {
8097 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
8098 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
8099 make a BIND_EXPR. Note that we nest in that because the cleanup may
8100 reference variables in the block. */
8112 /* Remove this group from the stack and add it to the free list. */
8118 }
8120 /* Return whether the current statement group may fall through. */
8124 {
8127 else
8129 }
8131 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
8132 statements.*/
8134 static void
8136 {
8137 Node_Id gnat_node;
8143 }
8145 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
8146 If BINDING_P is true, push and pop a binding level around the list. */
8148 static tree
8150 {
8162 }
8163 \f
8164 /* Generate GIMPLE in place for the expression at *EXPR_P. */
8166 int
8169 {
8172 tree op;
8178 {
8180 /* If this is an aggregate type, build a null pointer of the appropriate
8181 type and dereference it. */
8186 integer_zero_node));
8187 /* Otherwise, just make a VAR_DECL. */
8188 else
8189 {
8192 }
8198 /* We should only do this if we are just elaborating for side-effects,
8199 but we can't know that yet. */
8206 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
8207 is put into static memory. We know that it's going to be read-only
8208 given the semantics we have and it must be in static memory when the
8209 reference is in an elaboration procedure. */
8211 {
8215 }
8217 /* Replace atomic loads with their first argument. That's necessary
8218 because the gimplifier would create a temporary otherwise. */
8221 {
8224 {
8230 else
8232 }
8233 else
8235 }
8242 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
8243 type to a scalar one, explicitly create the local temporary. That's
8244 required if the type is passed by reference. */
8248 {
8257 }
8264 /* The expressions for the RM bounds must be gimplified to ensure that
8265 they are properly elaborated. See gimplify_decl_expr. */
8269 {
8274 {
8279 {
8283 }
8287 {
8291 }
8293 }
8298 }
8300 /* ... fall through ... */
8304 }
8305 }
8307 /* Generate GIMPLE in place for the statement at *STMT_P. */
8309 static enum gimplify_status
8311 {
8315 {
8321 {
8327 /* Build the condition expression from the test, if any. */
8329 {
8330 /* Deal with the optimization hints. */
8334 annot_expr_ivdep_kind));
8338 annot_expr_no_vector_kind));
8342 annot_expr_vector_kind));
8344 gnu_cond
8347 }
8349 /* Set to emit the statements of the loop. */
8352 /* We first emit the start label and then a conditional jump to the
8353 end label if there's a top condition, then the update if it's at
8354 the top, then the body of the loop, then a conditional jump to
8355 the end label if there's a bottom condition, then the update if
8356 it's at the bottom, and finally a jump to the start label and the
8357 definition of the end label. */
8359 gnu_start_label),
8360 stmt_p);
8381 gnu_end_label),
8382 stmt_p);
8384 }
8387 /* Build a statement to jump to the corresponding end label, then
8388 see if it needs to be conditional. */
8397 }
8398 }
8399 \f
8400 /* Force a reference to each of the entities in GNAT_PACKAGE recursively.
8402 This routine is exclusively called in type_annotate mode, to compute DDA
8403 information for types in withed units, for ASIS use. */
8405 static void
8407 {
8408 Entity_Id gnat_entity;
8413 {
8416 /* We are interested only in entities visible from the main unit. */
8420 /* Skip stuff internal to the compiler. */
8428 /* Skip named numbers. */
8432 /* Skip generic declarations. */
8436 /* Skip package bodies. */
8440 /* Skip limited views that point back to the main unit. */
8446 /* Skip types that aren't frozen. */
8450 /* Recurse on real packages that aren't in the main unit. */
8452 {
8456 }
8457 else
8459 }
8460 }
8462 /* Force a reference to each of the entities in packages withed by GNAT_NODE.
8463 Operate recursively but check that we aren't elaborating something more
8464 than once.
8466 This routine is exclusively called in type_annotate mode, to compute DDA
8467 information for types in withed units, for ASIS use. */
8469 static void
8471 {
8472 Entity_Id gnat_with_clause;
8474 /* Process each unit only once. As we trace the context of all relevant
8475 units transitively, including generic bodies, we may encounter the
8476 same generic unit repeatedly. */
8480 /* Save entities in all context units. A body may have an implicit_with
8481 on its own spec, if the context includes a child unit, so don't save
8482 the spec twice. */
8489 {
8499 {
8502 /* Retrieve compilation unit node of generic body. */
8507 /* If body is available, elaborate its context. */
8510 }
8511 }
8515 }
8516 \f
8517 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8519 static void
8521 {
8526 /* If this is a package, we need to generate code for the package. */
8528 {
8529 insert_code_for
8533 }
8535 /* Don't do anything for class-wide types as they are always transformed
8536 into their root type. */
8540 /* Check for an old definition. This freeze node might be for an Itype. */
8541 gnu_old
8544 /* If this entity has an address representation clause, GNU_OLD is the
8545 address, so discard it here. */
8549 /* Don't do anything for subprograms that may have been elaborated before
8550 their freeze nodes. This can happen, for example, because of an inner
8551 call in an instance body or because of previous compilation of a spec
8552 for inlining purposes. */
8560 /* If we have a non-dummy type old tree, we have nothing to do, except
8561 aborting if this is the public view of a private type whose full view was
8562 not delayed, as this node was never delayed as it should have been. We
8563 let this happen for concurrent types and their Corresponding_Record_Type,
8564 however, because each might legitimately be elaborated before its own
8565 freeze node, e.g. while processing the other. */
8569 {
8577 }
8579 /* Reset the saved tree, if any, and elaborate the object or type for real.
8580 If there is a full view, elaborate it and use the result. And, if this
8581 is the root type of a class-wide type, reuse it for the latter. */
8583 {
8588 {
8595 {
8598 }
8599 }
8605 }
8609 {
8618 /* Propagate back-annotations from full view to partial view. */
8628 /* The above call may have defined this entity (the simplest example
8629 of this is when we have a private enumeral type since the bounds
8630 will have the public view). */
8633 }
8634 else
8635 {
8636 tree gnu_init
8642 }
8649 /* If we have an old type and we've made pointers to this type, update those
8650 pointers. If this is a Taft amendment type in the main unit, we need to
8651 mark the type as used since other units referencing it don't see the full
8652 declaration and, therefore, cannot mark it as used themselves. */
8654 {
8659 }
8660 }
8661 \f
8662 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8663 We make two passes, one to elaborate anything other than bodies (but
8664 we declare a function if there was no spec). The second pass
8665 elaborates the bodies.
8667 GNAT_END_LIST gives the element in the list past the end. Normally,
8668 this is Empty, but can be First_Real_Statement for a
8669 Handled_Sequence_Of_Statements.
8671 We make a complete pass through both lists if PASS1P is true, then make
8672 the second pass over both lists if PASS2P is true. The lists usually
8673 correspond to the public and private parts of a package. */
8675 static void
8678 {
8680 Node_Id gnat_decl;
8690 {
8691 /* For package specs, we recurse inside the declarations,
8692 thus taking the two pass approach inside the boundary. */
8700 /* Similarly for any declarations in the actions of a
8701 freeze node. */
8703 {
8706 }
8708 /* Package bodies with freeze nodes get their elaboration deferred
8709 until the freeze node, but the code must be placed in the right
8710 place, so record the code position now. */
8718 (Corresponding_Spec
8721 record_code_position
8724 /* We defer most subprogram bodies to the second pass. */
8726 {
8728 {
8734 }
8735 }
8737 /* For bodies and stubs that act as their own specs, the entity
8738 itself must be elaborated in the first pass, because it may
8739 be used in other declarations. */
8741 {
8742 Node_Id gnat_subprog_id
8749 }
8751 /* Concurrent stubs stand for the corresponding subprogram bodies,
8752 which are deferred like other bodies. */
8755 ;
8757 /* Renamed subprograms may not be elaborated yet at this point
8758 since renamings do not trigger freezing. Wait for the second
8759 pass to take care of them. */
8761 ;
8763 else
8765 }
8767 /* Here we elaborate everything we deferred above except for package bodies,
8768 which are elaborated at their freeze nodes. Note that we must also
8769 go inside things (package specs and freeze nodes) the first pass did. */
8775 {
8794 }
8795 }
8796 \f
8797 /* Make a unary operation of kind CODE using build_unary_op, but guard
8798 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8799 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8800 the operation is to be performed in that type. GNAT_NODE is the gnat
8801 node conveying the source location for which the error should be
8802 signaled. */
8804 static tree
8806 Node_Id gnat_node)
8807 {
8816 }
8818 /* Make a binary operation of kind CODE using build_binary_op, but guard
8819 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8820 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8821 Usually the operation is to be performed in that type. GNAT_NODE is
8822 the GNAT node conveying the source location for which the error should
8823 be signaled. */
8825 static tree
8828 {
8838 /* Assert that the precision is a power of 2. */
8841 /* Prefer a constant or known-positive rhs to simplify checks. */
8847 {
8851 }
8855 /* If we can fold the expression to a constant, just return it.
8856 The caller will deal with overflow, no need to generate a check. */
8861 ? boolean_false_node
8864 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8866 /* Try a few strategies that may be cheaper than the general
8867 code at the end of the function, if the rhs is not known.
8868 The strategies are:
8869 - Call library function for 64-bit multiplication (complex)
8870 - Widen, if input arguments are sufficiently small
8871 - Determine overflow using wrapped result for addition/subtraction. */
8874 {
8875 /* Even for add/subtract double size to get another base type. */
8879 {
8885 }
8889 {
8895 check = build_binary_op
8902 return
8904 }
8907 {
8909 tree wrapped_expr
8915 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8916 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8917 check
8921 boolean_type_node,
8924 return
8926 }
8927 }
8930 {
8932 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8937 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8944 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8949 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8956 /* The check here is designed to be efficient if the rhs is constant,
8957 but it will work for any rhs by using integer division.
8958 Four different check expressions determine whether X * C overflows,
8959 depending on C.
8960 C == 0 => false
8961 C > 0 => X > type_max / C || X < type_min / C
8962 C == -1 => X == type_min
8963 C < -1 => X > type_min / C || X < type_max / C */
8968 check_pos
8971 rhs),
8974 boolean_type_node,
8977 boolean_type_node,
8980 check_neg
8985 type_min),
8988 boolean_type_node,
8991 boolean_type_node,
8997 }
9000 check_pos);
9003 }
9005 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
9006 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
9007 which we have to check. GNAT_NODE is the GNAT node conveying the source
9008 location for which the error should be signaled. */
9010 static tree
9012 {
9016 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
9017 This can for example happen when translating 'Val or 'Value. */
9021 /* Range checks can only be applied to types with ranges. */
9025 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
9026 we can't do anything since we might be truncating the bounds. No
9027 check is needed in this case. */
9033 /* Checked expressions must be evaluated only once. */
9036 /* Note that the form of the check is
9037 (not (expr >= lo)) or (not (expr <= hi))
9038 the reason for this slightly convoluted form is that NaNs
9039 are not considered to be in range in the float case. */
9040 return emit_check
9042 invert_truthvalue
9046 TYPE_MIN_VALUE
9048 invert_truthvalue
9052 TYPE_MAX_VALUE
9055 }
9056 \f
9057 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
9058 we are about to index, GNU_EXPR is the index expression to be checked,
9059 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
9060 has to be checked. Note that for index checking we cannot simply use the
9061 emit_range_check function (although very similar code needs to be generated
9062 in both cases) since for index checking the array type against which we are
9063 checking the indices may be unconstrained and consequently we need to get
9064 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
9065 The place where we need to do that is in subprograms having unconstrained
9066 array formal parameters. GNAT_NODE is the GNAT node conveying the source
9067 location for which the error should be signaled. */
9069 static tree
9072 {
9073 tree gnu_expr_check;
9075 /* Checked expressions must be evaluated only once. */
9078 /* Must do this computation in the base type in case the expression's
9079 type is an unsigned subtypes. */
9082 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
9083 the object we are handling. */
9087 return emit_check
9090 gnu_expr_check,
9092 gnu_low)),
9094 gnu_expr_check,
9096 gnu_high))),
9098 }
9099 \f
9100 /* GNU_COND contains the condition corresponding to an index, overflow or
9101 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR
9102 if GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
9103 REASON is the code that says why the exception is raised. GNAT_NODE is
9104 the node conveying the source location for which the error should be
9105 signaled.
9107 We used to propagate TREE_SIDE_EFFECTS from GNU_EXPR to the COND_EXPR,
9108 overwriting the setting inherited from the call statement, on the ground
9109 that the expression need not be evaluated just for the check. However
9110 that's incorrect because, in the GCC type system, its value is presumed
9111 to be valid so its comparison against the type bounds always yields true
9112 and, therefore, could be done without evaluating it; given that it can
9113 be a computation that overflows the bounds, the language may require the
9114 check to fail and thus the expression to be evaluated in this case. */
9116 static tree
9118 {
9119 tree gnu_call
9121 return
9125 gnu_expr);
9126 }
9127 \f
9128 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
9129 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
9130 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
9131 float to integer conversion with truncation; otherwise round.
9132 GNAT_NODE is the GNAT node conveying the source location for which the
9133 error should be signaled. */
9135 static tree
9138 {
9145 /* If we are not doing any checks, the output is an integral type and the
9146 input is not a floating-point type, just do the conversion. This is
9147 required for packed array types and is simpler in all cases anyway. */
9149 && !overflowp
9154 /* First convert the expression to its base type. This
9155 will never generate code, but makes the tests below much simpler.
9156 But don't do this if converting from an integer type to an unconstrained
9157 array type since then we need to get the bounds from the original
9158 (unpacked) type. */
9162 /* If overflow checks are requested, we need to be sure the result will
9163 fit in the output base type. But don't do this if the input
9164 is integer and the output floating-point. */
9167 {
9168 /* Ensure GNU_EXPR only gets evaluated once. */
9176 /* Convert the lower bounds to signed types, so we're sure we're
9177 comparing them properly. Likewise, convert the upper bounds
9178 to unsigned types. */
9192 /* Check each bound separately and only if the result bound
9193 is tighter than the bound on the input type. Note that all the
9194 types are base types, so the bounds must be constant. Also,
9195 the comparison is done in the base type of the input, which
9196 always has the proper signedness. First check for input
9197 integer (which means output integer), output float (which means
9198 both float), or mixed, in which case we always compare.
9199 Note that we have to do the comparison which would *fail* in the
9200 case of an error since if it's an FP comparison and one of the
9201 values is a NaN or Inf, the comparison will fail. */
9208 gnu_cond
9209 = invert_truthvalue
9212 gnu_out_lb)));
9220 gnu_cond
9222 invert_truthvalue
9224 gnu_input,
9226 gnu_out_ub))));
9231 }
9233 /* Now convert to the result base type. If this is a non-truncating
9234 float-to-integer conversion, round. */
9238 {
9244 /* The following calculations depend on proper rounding to even
9245 of each arithmetic operation. In order to prevent excess
9246 precision from spoiling this property, use the widest hardware
9247 floating-point type if FP_ARITH_MAY_WIDEN is true. */
9248 calc_type
9251 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
9258 /* If the input is strictly negative, subtract this value
9259 and otherwise add it from the input. For 0.5, the result
9260 is exactly between 1.0 and the machine number preceding 1.0
9261 (for calc_type). Since the last bit of 1.0 is even, this 0.5
9262 will round to 1.0, while all other number with an absolute
9263 value less than 0.5 round to 0.0. For larger numbers exactly
9264 halfway between integers, rounding will always be correct as
9265 the true mathematical result will be closer to the higher
9266 integer compared to the lower one. So, this constant works
9267 for all floating-point numbers.
9269 The reason to use the same constant with subtract/add instead
9270 of a positive and negative constant is to allow the comparison
9271 to be scheduled in parallel with retrieval of the constant and
9272 conversion of the input to the calc_type (if necessary). */
9277 gnu_comp
9279 gnu_add_pred_half
9281 gnu_subtract_pred_half
9285 }
9291 else
9294 /* Finally, do the range check if requested. Note that if the result type
9295 is a modular type, the range check is actually an overflow check. */
9302 }
9303 \f
9304 /* Return true if GNU_EXPR can be directly addressed. This is the case
9305 unless it is an expression involving computation or if it involves a
9306 reference to a bitfield or to an object not sufficiently aligned for
9307 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
9308 be directly addressed as an object of this type.
9310 *** Notes on addressability issues in the Ada compiler ***
9312 This predicate is necessary in order to bridge the gap between Gigi
9313 and the middle-end about addressability of GENERIC trees. A tree
9314 is said to be addressable if it can be directly addressed, i.e. if
9315 its address can be taken, is a multiple of the type's alignment on
9316 strict-alignment architectures and returns the first storage unit
9317 assigned to the object represented by the tree.
9319 In the C family of languages, everything is in practice addressable
9320 at the language level, except for bit-fields. This means that these
9321 compilers will take the address of any tree that doesn't represent
9322 a bit-field reference and expect the result to be the first storage
9323 unit assigned to the object. Even in cases where this will result
9324 in unaligned accesses at run time, nothing is supposed to be done
9325 and the program is considered as erroneous instead (see PR c/18287).
9327 The implicit assumptions made in the middle-end are in keeping with
9328 the C viewpoint described above:
9329 - the address of a bit-field reference is supposed to be never
9330 taken; the compiler (generally) will stop on such a construct,
9331 - any other tree is addressable if it is formally addressable,
9332 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
9334 In Ada, the viewpoint is the opposite one: nothing is addressable
9335 at the language level unless explicitly declared so. This means
9336 that the compiler will both make sure that the trees representing
9337 references to addressable ("aliased" in Ada parlance) objects are
9338 addressable and make no real attempts at ensuring that the trees
9339 representing references to non-addressable objects are addressable.
9341 In the first case, Ada is effectively equivalent to C and handing
9342 down the direct result of applying ADDR_EXPR to these trees to the
9343 middle-end works flawlessly. In the second case, Ada cannot afford
9344 to consider the program as erroneous if the address of trees that
9345 are not addressable is requested for technical reasons, unlike C;
9346 as a consequence, the Ada compiler must arrange for either making
9347 sure that this address is not requested in the middle-end or for
9348 compensating by inserting temporaries if it is requested in Gigi.
9350 The first goal can be achieved because the middle-end should not
9351 request the address of non-addressable trees on its own; the only
9352 exception is for the invocation of low-level block operations like
9353 memcpy, for which the addressability requirements are lower since
9354 the type's alignment can be disregarded. In practice, this means
9355 that Gigi must make sure that such operations cannot be applied to
9356 non-BLKmode bit-fields.
9358 The second goal is achieved by means of the addressable_p predicate,
9359 which computes whether a temporary must be inserted by Gigi when the
9360 address of a tree is requested; if so, the address of the temporary
9361 will be used in lieu of that of the original tree and some glue code
9362 generated to connect everything together. */
9364 static bool
9366 {
9367 /* For an integral type, the size of the actual type of the object may not
9368 be greater than that of the expected type, otherwise an indirect access
9369 in the latter type wouldn't correctly set all the bits of the object. */
9375 /* The size of the actual type of the object may not be smaller than that
9376 of the expected type, otherwise an indirect access in the latter type
9377 would be larger than the object. But only record types need to be
9378 considered in practice for this case. */
9385 {
9390 /* All DECLs are addressable: if they are in a register, we can force
9391 them to memory. */
9396 /* Taking the address of a dereference yields the original pointer. */
9401 /* Taking the address yields a pointer to the constant pool. */
9405 /* Taking the address of a static constructor yields a pointer to the
9406 tree constant pool. */
9418 /* All rvalues are deemed addressable since taking their address will
9419 force a temporary to be created by the middle-end. */
9423 /* The address of a compound expression is that of its 2nd operand. */
9427 /* We accept &COND_EXPR as soon as both operands are addressable and
9428 expect the outcome to be the address of the selected operand. */
9434 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
9435 the field is sufficiently aligned, in case it is subject
9436 to a pragma Component_Alignment. But we don't need to
9437 check the alignment of the containing record, as it is
9438 guaranteed to be not smaller than that of its most
9439 aligned field that is not a bit-field. */
9440 && (!STRICT_ALIGNMENT
9443 /* The field of a padding record is always addressable. */
9457 {
9458 /* This is addressable if we can avoid a copy. */
9462 && (!STRICT_ALIGNMENT
9467 && (!STRICT_ALIGNMENT
9473 }
9477 }
9478 }
9479 \f
9480 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
9481 a separate Freeze node exists, delay the bulk of the processing. Otherwise
9482 make a GCC type for GNAT_ENTITY and set up the correspondence. */
9484 void
9486 {
9487 tree gnu_old
9489 tree gnu_new;
9491 /* If we are to delay elaboration of this type, just do any
9492 elaborations needed for expressions within the declaration and
9493 make a dummy type entry for this node and its Full_View (if
9494 any) in case something points to it. Don't do this if it
9495 has already been done (the only way that can happen is if
9496 the private completion is also delayed). */
9502 {
9506 {
9511 {
9515 }
9516 }
9519 }
9521 /* If we saved away a dummy type for this node it means that this
9522 made the type that corresponds to the full type of an incomplete
9523 type. Clear that type for now and then update the type in the
9524 pointers. */
9526 {
9531 }
9533 /* Now fully elaborate the type. */
9537 /* If we have an old type and we've made pointers to this type, update those
9538 pointers. If this is a Taft amendment type in the main unit, we need to
9539 mark the type as used since other units referencing it don't see the full
9540 declaration and, therefore, cannot mark it as used themselves. */
9542 {
9547 }
9549 /* If this is a record type corresponding to a task or protected type
9550 that is a completion of an incomplete type, perform a similar update
9551 on the type. ??? Including protected types here is a guess. */
9555 {
9556 tree gnu_task_old
9566 }
9567 }
9568 \f
9569 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9570 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9571 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9573 static tree
9575 {
9578 /* We test for GNU_FIELD being empty in the case where a variant
9579 was the last thing since we don't take things off GNAT_ASSOC in
9580 that case. We check GNAT_ASSOC in case we have a variant, but it
9581 has no fields. */
9584 {
9589 /* The expander is supposed to put a single component selector name
9590 in every record component association. */
9593 /* Ignore fields that have Corresponding_Discriminants since we'll
9594 be setting that field in the parent. */
9599 /* Also ignore discriminants of Unchecked_Unions. */
9604 /* Before assigning a value in an aggregate make sure range checks
9605 are done if required. Then convert to the type of the field. */
9611 /* Add the field and expression to the list. */
9613 }
9618 {
9619 /* Verify that every entry in GNU_LIST was used. */
9622 }
9625 }
9627 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9628 the first element of an array aggregate. It may itself be an aggregate.
9629 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9630 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9631 for range checking. */
9633 static tree
9635 Entity_Id gnat_component_type)
9636 {
9638 tree gnu_expr;
9642 {
9643 /* If the expression is itself an array aggregate then first build the
9644 innermost constructor if it is part of our array (multi-dimensional
9645 case). */
9651 gnat_component_type);
9652 else
9653 {
9656 /* Before assigning the element to the array, make sure it is
9657 in range. */
9660 }
9667 integer_one_node));
9668 }
9671 }
9672 \f
9673 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9674 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
9675 associations that are from RECORD_TYPE. If we see an internal record, make
9676 a recursive call to fill it in as well. */
9678 static tree
9680 {
9685 {
9688 /* _Parent is an internal field, but may have values in the aggregate,
9689 so check for values first. */
9691 {
9694 }
9697 {
9702 }
9703 else
9704 /* If we have a record subtype, the names will match, but not the
9705 actual FIELD_DECLs. */
9708 {
9711 }
9717 }
9720 }
9721 \f
9722 /* Process a N_Validate_Unchecked_Conversion node. */
9724 static void
9726 {
9730 /* If the target is a pointer type, see if we are either converting from a
9731 non-pointer or from a pointer to a type with a different alias set and
9732 warn if so, unless the pointer has been marked to alias everything. */
9735 {
9745 target_alias_set)))
9746 {
9750 gnat_node);
9753 }
9754 }
9756 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9757 mitigate the problem in this case, so we unconditionally warn. */
9759 {
9760 tree gnu_source_desig_type
9764 tree gnu_target_desig_type
9771 target_alias_set)))
9772 {
9776 gnat_node);
9777 }
9778 }
9779 }
9780 \f
9781 /* EXP is to be treated as an array or record. Handle the cases when it is
9782 an access object and perform the required dereferences. */
9784 static tree
9786 {
9787 /* If the type is a pointer, dereference it. */
9792 /* If we got a padded type, remove it too. */
9797 }
9798 \f
9799 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9800 location and false if it doesn't. If CLEAR_COLUMN is true, set the column
9801 information to 0. */
9803 bool
9805 {
9810 {
9813 }
9820 /* We can have zero if pragma Source_Reference is in effect. */
9824 /* Translate the location. */
9829 }
9831 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9832 don't do anything if it doesn't correspond to a source location. And,
9833 if CLEAR_COLUMN is true, set the column information to 0. */
9835 static void
9837 {
9838 location_t locus;
9844 }
9846 /* More elaborate version of set_expr_location_from_node to be used in more
9847 general contexts, for example the result of the translation of a generic
9848 GNAT node. */
9850 static void
9852 {
9853 /* Set the location information on the node if it is a real expression.
9854 References can be reused for multiple GNAT nodes and they would get
9855 the location information of their last use. Also make sure not to
9856 overwrite an existing location as it is probably more precise. */
9859 {
9860 CASE_CONVERT:
9869 /* ... fall through ... */
9873 {
9876 }
9878 }
9879 }
9881 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9882 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9883 most sense. Return true if a sensible assignment was performed. */
9885 static bool
9887 {
9888 Node_Id gnat_end_label;
9889 location_t end_locus;
9891 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9892 end_locus when there is one. We consider only GNAT nodes with a possible
9893 End_Label attached. If the End_Label actually was unassigned, fallback
9894 on the original node. We'd better assign an explicit sloc associated with
9895 the outer construct in any case. */
9898 {
9911 }
9916 /* Some expanded subprograms have neither an End_Label nor a Sloc
9917 attached. Notify that to callers. For a block statement with no
9918 End_Label, clear column information, so that the tree for a
9919 transient block does not receive the sloc of a source condition. */
9926 {
9937 }
9938 }
9939 \f
9940 /* Return a colon-separated list of encodings contained in encoded Ada
9941 name. */
9945 {
9949 }
9951 /* Extract the Ada name from an encoded name. */
9955 {
9959 }
9960 \f
9961 /* Post an error message. MSG is the error message, properly annotated.
9962 NODE is the node at which to post the error and the node to use for the
9963 '&' substitution. */
9965 void
9967 {
9968 String_Template temp;
9969 String_Pointer sp;
9979 }
9981 /* Similar to post_error, but NODE is the node at which to post the error and
9982 ENT is the node to use for the '&' substitution. */
9984 void
9986 {
9987 String_Template temp;
9988 String_Pointer sp;
9998 }
10000 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
10002 void
10004 {
10007 }
10009 /* Similar to post_error_ne, but T is a GCC tree representing the number to
10010 write. If T represents a constant, the text inside curly brackets in
10011 MSG will be output (presumably including a '^'). Otherwise it will not
10012 be output and the text inside square brackets will be output instead. */
10014 void
10016 {
10023 {
10026 }
10027 else
10031 {
10037 ;
10038 else
10040 }
10045 }
10047 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
10049 void
10052 {
10055 }
10056 \f
10057 /* Initialize the table that maps GNAT codes to GCC codes for simple
10058 binary and unary operations. */
10060 static void
10062 {
10088 }
10090 /* Return a label to branch to for the exception type in KIND or NULL_TREE
10091 if none. */
10093 tree
10095 {
10102 else
10104 }
10106 /* Return the decl for the current elaboration procedure. */
10108 tree
10110 {
10112 }