| blob | 5ee82ec6f92ab582080cf4d3354b9f0d11474b68 |
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 type;
184 tree invariant_cond;
185 tree inserted_cond;
186 };
191 /* Structure used to record information for a loop. */
193 tree stmt;
194 tree loop_var;
195 tree low_bound;
196 tree high_bound;
201 };
206 /* Stack of loop_info structures associated with LOOP_STMT nodes. */
209 /* The stacks for N_{Push,Pop}_*_Label. */
214 /* Map GNAT tree codes to GCC tree codes for simple expressions. */
249 /* Hooks for debug info back-ends, only supported and used in a restricted set
250 of configurations. */
253 \f
254 /* This is the main program of the back-end. It sets up all the table
255 structures and then generates code. */
257 void
270 Nat number_file,
272 Entity_Id standard_boolean,
273 Entity_Id standard_integer,
274 Entity_Id standard_character,
275 Entity_Id standard_long_long_float,
276 Entity_Id standard_exception_type,
277 Int gigi_operating_mode)
278 {
279 Node_Id gnat_iter;
280 Entity_Id gnat_literal;
300 {
301 /* Use the identifier table to make a permanent copy of the filename as
302 the name table gets reallocated after Gigi returns but before all the
303 debugging information is output. The __gnat_to_canonical_file_spec
304 call translates filenames from pragmas Source_Reference that contain
305 host style syntax not understood by gdb. */
307 = IDENTIFIER_POINTER
308 (get_identifier
309 (__gnat_to_canonical_file_spec
312 /* We rely on the order isomorphism between files and line maps. */
315 /* We create the line map for a source file at once, with a fixed number
316 of columns chosen to avoid jumping over the next power of 2. */
321 }
325 /* Declare the name of the compilation unit as the first global
326 name in order to make the middle-end fully deterministic. */
330 /* Initialize ourselves. */
335 /* If we are just annotating types, give VOID_TYPE zero sizes to avoid
336 errors. */
338 {
341 }
343 /* Enable GNAT stack checking method if needed */
347 /* Retrieve alignment settings. */
351 /* Record the builtin types. Define `integer' and `character' first so that
352 dbx will output them first. */
358 /* Save the type we made for integer as the type for Standard.Integer. */
363 /* Likewise for character as the type for Standard.Character. */
368 /* Likewise for boolean as the type for Standard.Boolean. */
390 /* Now declare run-time functions. */
393 /* malloc is a function declaration tree for a function to allocate
394 memory. */
395 malloc_decl
397 ftype,
402 /* free is a function declaration tree for a function to free memory. */
403 free_decl
406 ptr_type_node,
407 NULL_TREE),
411 /* This is used for 64-bit multiplication with overflow checking. */
413 mulv64_decl
420 /* Name of the _Parent field in tagged record types. */
423 /* Name of the Exception_Data type defined in System.Standard_Library. */
424 exception_data_name_id
427 /* Make the types and functions used for exception processing. */
430 jmpbuf_type
436 /* Functions to get and set the jumpbuf pointer for the current thread. */
437 get_jmpbuf_decl
438 = create_subprog_decl
443 set_jmpbuf_decl
444 = create_subprog_decl
447 NULL_TREE),
450 get_excptr_decl
451 = create_subprog_decl
454 NULL_TREE),
460 {
463 }
466 /* setjmp returns an integer and has one operand, which is a pointer to
467 a jmpbuf. */
468 setjmp_decl
469 = create_subprog_decl
472 NULL_TREE),
477 /* update_setjmp_buf updates a setjmp buffer from the current stack pointer
478 address. */
479 update_setjmp_buf_decl
480 = create_subprog_decl
487 raise_nodefer_decl
488 = create_subprog_decl
492 NULL_TREE),
495 /* Indicate that it never returns. */
500 TYPE_QUAL_VOLATILE);
502 reraise_zcx_decl
507 /* Indicate that these never return. */
513 set_exception_parameter_decl
514 = create_subprog_decl
517 NULL_TREE),
520 /* Hooks to call when entering/leaving an exception handler. */
523 begin_handler_decl
529 end_handler_decl
535 unhandled_except_decl
541 /* Dummy objects to materialize "others" and "all others" in the exception
542 tables. These are exported by a-exexpr-gcc.adb, so see this unit for
543 the types to use. */
544 others_decl
551 all_others_decl
558 unhandled_others_decl
565 /* If in no exception handlers mode, all raise statements are redirected to
566 __gnat_last_chance_handler. No need to redefine raise_nodefer_decl since
567 this procedure will never be called in this mode. */
569 {
570 tree decl
571 = create_subprog_decl
574 build_pointer_type
584 }
585 else
586 {
587 /* Otherwise, make one decl for each exception reason. */
593 i == CE_Index_Check_Failed
597 }
599 /* Build the special descriptor type and its null node if needed. */
601 {
613 {
614 tree field
621 elt--;
622 }
627 }
629 longest_float_type_node
634 /* Install the builtins we might need, either internally or as
635 user available facilities for Intrinsic imports. */
643 /* Process any Pragma Ident for the main unit. */
648 /* If we are using the GCC exception mechanism, let GCC know. */
652 /* Initialize the GCC support for FP operations. */
655 /* Force -fno-strict-aliasing if the configuration pragma was seen. */
659 /* Save the current optimization options again after the above possible
660 global_options changes. */
664 /* Now translate the compilation unit proper. */
667 /* Disable -Waggressive-loop-optimizations since we implement our own
668 version of the warning. */
671 /* Then process the N_Validate_Unchecked_Conversion nodes. We do this at
672 the very end to avoid having to second-guess the front-end when we run
673 into dummy nodes during the regular processing. */
678 /* Finally see if we have any elaboration procedures to deal with. */
680 {
683 /* We should have a BIND_EXPR but it may not have any statements in it.
684 If it doesn't have any, we have nothing to do except for setting the
685 flag on the GNAT node. Otherwise, process the function as others. */
691 else
692 {
696 }
697 }
699 /* Destroy ourselves. */
703 /* We cannot track the location of errors past this point. */
705 }
706 \f
707 /* Return a subprogram decl corresponding to __gnat_rcheck_xx for the given
708 CHECK if KIND is EXCEPTION_SIMPLE, or else to __gnat_rcheck_xx_ext. */
710 static tree
712 {
721 {
723 ftype
725 build_pointer_type
728 }
729 else
730 {
735 ftype
737 build_pointer_type
741 }
743 result
749 /* Indicate that it never returns. */
756 }
757 \f
758 /* Return a positive value if an lvalue is required for GNAT_NODE, which is
759 an N_Attribute_Reference. */
761 static int
763 {
765 {
805 }
806 }
808 /* Return a positive value if an lvalue is required for GNAT_NODE. GNU_TYPE
809 is the type that will be used for GNAT_NODE in the translated GNU tree.
810 CONSTANT indicates whether the underlying object represented by GNAT_NODE
811 is constant in the Ada sense. If it is, ADDRESS_OF_CONSTANT indicates
812 whether its value is the address of a constant and ALIASED whether it is
813 aliased. If it isn't, ADDRESS_OF_CONSTANT and ALIASED are ignored.
815 The function climbs up the GNAT tree starting from the node and returns 1
816 upon encountering a node that effectively requires an lvalue downstream.
817 It returns int instead of bool to facilitate usage in non-purely binary
818 logic contexts. */
820 static int
823 {
827 {
837 /* If the parameter is by reference, an lvalue is required. */
843 /* Only the array expression can require an lvalue. */
847 /* ??? Consider that referencing an indexed component with a variable
848 index forces the whole aggregate to memory. Note that testing only
849 for literals is conservative, any static expression in the RM sense
850 could probably be accepted with some additional work. */
860 /* ... fall through ... */
863 /* Only the array expression can require an lvalue. */
877 /* We need to preserve addresses through a renaming. */
881 /* We cannot use a constructor if this is an atomic object because
882 the actual assignment might end up being done component-wise. */
886 /* We don't use a constructor if this is a class-wide object
887 because the effective type of the object is the equivalent
888 type of the class-wide subtype and it smashes most of the
889 data into an array of bytes to which we cannot convert. */
894 /* We cannot use a constructor if the LHS is an atomic object because
895 the actual assignment might end up being done component-wise. */
906 /* ... fall through ... */
910 /* We must look through all conversions because we may need to bypass
911 an intermediate conversion that is meant to be purely formal. */
917 /* We should only reach here through the N_Qualified_Expression case.
918 Force an lvalue for composite types since a block-copy to the newly
919 allocated area of memory is made. */
923 /* We look through dereferences for address of constant because we need
924 to handle the special cases listed above. */
930 /* ... fall through ... */
934 }
937 }
939 /* Return true if T is a constant DECL node that can be safely replaced
940 by its initializer. */
942 static bool
944 {
948 /* Return false for aggregate types that contain a placeholder since
949 their initializers cannot be manipulated easily. */
956 }
958 /* Return an expression equivalent to EXP but where constant DECL nodes
959 have been replaced by their initializer. */
961 static tree
963 {
965 tree op0;
968 {
987 /* If the index is not itself constant, then nothing can be folded. */
1008 }
1011 }
1013 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Identifier,
1014 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer
1015 to where we should place the result type. */
1017 static tree
1019 {
1023 /* Whether we should require an lvalue for GNAT_NODE. Needed in
1024 specific circumstances only, so evaluated lazily. < 0 means
1025 unknown, > 0 means known true, 0 means known false. */
1028 /* If GNAT_NODE is a constant, whether we should use the initialization
1029 value instead of the constant entity, typically for scalars with an
1030 address clause when the parent doesn't require an lvalue. */
1033 /* If the Etype of this node does not equal the Etype of the Entity,
1034 something is wrong with the entity map, probably in generic
1035 instantiation. However, this does not apply to types. Since we sometime
1036 have strange Ekind's, just do this test for objects. Also, if the Etype of
1037 the Entity is private, the Etype of the N_Identifier is allowed to be the
1038 full type and also we consider a packed array type to be the same as the
1039 original type. Similarly, a class-wide type is equivalent to a subtype of
1040 itself. Finally, if the types are Itypes, one may be a copy of the other,
1041 which is also legal. */
1057 == Packed_Array_Impl_Type
1066 /* If this is a reference to a deferred constant whose partial view is an
1067 unconstrained private type, the proper type is on the full view of the
1068 constant, not on the full view of the type, which may be unconstrained.
1070 This may be a reference to a type, for example in the prefix of the
1071 attribute Position, generated for dispatching code (see Make_DT in
1072 exp_disp,adb). In that case we need the type itself, not is parent,
1073 in particular if it is a derived type */
1080 {
1083 }
1084 else
1085 {
1086 /* We want to use the Actual_Subtype if it has already been elaborated,
1087 otherwise the Etype. Avoid using Actual_Subtype for packed arrays to
1088 simplify things. */
1096 else
1098 }
1100 /* Expand the type of this identifier first, in case it is an enumeral
1101 literal, which only get made when the type is expanded. There is no
1102 order-of-elaboration issue here. */
1105 /* If this is a non-imported elementary constant with an address clause,
1106 retrieve the value instead of a pointer to be dereferenced unless
1107 an lvalue is required. This is generally more efficient and actually
1108 required if this is a static expression because it might be used
1109 in a context where a dereference is inappropriate, such as a case
1110 statement alternative or a record discriminant. There is no possible
1111 volatile-ness short-circuit here since Volatile constants must be
1112 imported per C.6. */
1117 {
1121 }
1124 {
1125 /* If this is a deferred constant, the initializer is attached to
1126 the full view. */
1131 }
1132 else
1135 /* Some objects (such as parameters passed by reference, globals of
1136 variable size, and renamed objects) actually represent the address
1137 of the object. In that case, we must do the dereference. Likewise,
1138 deal with parameters to foreign convention subprograms. */
1143 {
1146 /* If it's a PARM_DECL to foreign convention subprogram, convert it. */
1149 gnu_result
1152 /* If it's a CONST_DECL, return the underlying constant like below. */
1159 /* If it's a renaming pointer, get to the renamed object. */
1165 /* Otherwise, do the final dereference. */
1166 else
1167 {
1177 }
1178 }
1180 /* If we have a constant declaration and its initializer, try to return the
1181 latter to avoid the need to call fold in lots of places and the need for
1182 elaboration code if this identifier is used as an initializer itself. */
1184 {
1190 /* If there is a (corresponding) variable or this is the address of a
1191 constant, we only want to return the initializer if an lvalue isn't
1192 required. Evaluate this now if we have not already done so. */
1194 require_lvalue
1198 /* Finally retrieve the initializer if this is deemed valid. */
1201 }
1203 /* But for a constant renaming we couldn't do that incrementally for its
1204 definition because of the need to return an lvalue so, if the present
1205 context doesn't itself require an lvalue, we try again here. */
1209 {
1211 require_lvalue
1216 }
1218 /* The GNAT tree has the type of a function set to its result type, so we
1219 adjust here. Also use the type of the result if the Etype is a subtype
1220 that is nominally unconstrained. Likewise if this is a deferred constant
1221 of a discriminated type whose full view can be elaborated statically, to
1222 avoid problematic conversions to the nominal subtype. But remove any
1223 padding from the resulting type. */
1230 {
1234 }
1239 }
1240 \f
1241 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Pragma. Return
1242 any statements we generate. */
1244 static tree
1246 {
1249 Node_Id gnat_temp;
1251 /* Do nothing if we are just annotating types and check for (and ignore)
1252 unrecognized pragmas. */
1259 {
1261 /* Do nothing at top level: all such variables are already viewable. */
1268 {
1272 machine_mode mode;
1274 #ifdef ASM_COMMENT_START
1276 #endif
1281 /* Use the value only if it fits into a normal register,
1282 otherwise use the address. */
1291 #ifdef ASM_COMMENT_START
1297 NULL);
1300 #endif
1302 asm_constraint,
1303 NULL_TREE,
1304 tree_cons
1312 }
1319 {
1323 {
1346 }
1347 }
1353 {
1371 }
1381 {
1382 Node_Id gnat_expr;
1383 /* Preserve the location of the pragma. */
1387 diagnostic_t kind;
1392 /* This is the String form: pragma Warning{s|_As_Error}(String). */
1394 {
1396 {
1409 }
1412 }
1414 /* This is the On/Off form: pragma Warnings (On | Off [,String]). */
1416 {
1418 {
1429 }
1431 /* Deal with optional pattern (but ignore Reason => "..."). */
1434 {
1435 /* pragma Warnings (On | Off, Name) is handled differently. */
1440 }
1441 else
1445 }
1447 else
1450 /* This is the same implementation as in the C family of compilers. */
1453 {
1461 {
1464 }
1466 {
1469 }
1471 {
1474 }
1475 }
1476 else
1483 }
1488 }
1491 }
1492 \f
1494 /* Check the inlining status of nested function FNDECL in the current context.
1496 If a non-inline nested function is referenced from an inline external
1497 function, we cannot honor both requests at the same time without cloning
1498 the nested function in the current unit since it is private to its unit.
1499 We could inline it as well but it's probably better to err on the side
1500 of too little inlining.
1502 This must be invoked only on nested functions present in the source code
1503 and not on nested functions generated by the compiler, e.g. finalizers,
1504 because they are not marked inline and we don't want them to block the
1505 inlining of the parent function. */
1507 static void
1509 {
1511 && current_function_decl
1514 {
1520 {
1523 }
1524 else
1525 {
1527 fndecl);
1529 }
1533 }
1534 }
1535 \f
1536 /* Return an expression for the length of TYPE, an integral type, computed in
1537 RESULT_TYPE, another integral type.
1539 We used to compute the length as MAX (hb - lb + 1, 0) which could overflow
1540 when lb == TYPE'First. We now compute it as (hb >= lb) ? hb - lb + 1 : 0
1541 which would only overflow in much rarer cases, for extremely large arrays
1542 we expect never to encounter in practice. Besides, the former computation
1543 required the use of potentially constraining signed arithmetics while the
1544 latter does not. Note that the comparison must be done in the original
1545 base index type in order to avoid any overflow during the conversion. */
1547 static tree
1549 {
1554 tree length
1560 length
1566 }
1568 /* Subroutine of gnat_to_gnu to translate GNAT_NODE, an N_Attribute node,
1569 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to
1570 where we should place the result type. ATTRIBUTE is the attribute ID. */
1572 static tree
1574 {
1580 /* ??? If this is an access attribute for a public subprogram to be used in
1581 a dispatch table, do not translate its type as it's useless in this case
1582 and the parameter types might be incomplete types coming from a limited
1583 context in Ada 2012 (AI05-0151). */
1591 else
1595 /* If the input is a NULL_EXPR, make a new one. */
1597 {
1601 }
1604 {
1607 /* These are just conversions since representation clauses for
1608 enumeration types are handled in the front-end. */
1609 {
1615 }
1620 /* These just add or subtract the constant 1 since representation
1621 clauses for enumeration types are handled in the front-end. */
1626 {
1628 gnu_expr
1629 = emit_check
1631 gnu_expr,
1632 attribute == Attr_Pred
1636 }
1638 gnu_result
1646 /* Conversions don't change addresses but can cause us to miss the
1647 COMPONENT_REF case below, so strip them off. */
1651 /* If we are taking 'Address of an unconstrained object, this is the
1652 pointer to the underlying array. */
1656 /* If we are building a static dispatch table, we have to honor
1657 TARGET_VTABLE_USES_DESCRIPTORS if we want to be compatible
1658 with the C++ ABI. We do it in the non-static case as well,
1659 see gnat_to_gnu_entity, case E_Access_Subprogram_Type. */
1662 {
1664 /* Descriptors can only be built here for top-level functions. */
1672 /* If we're not going to build the descriptor, we have to retrieve
1673 the one which will be built by the linker (or by the compiler
1674 later if a static chain is requested). */
1676 {
1679 gnu_result);
1681 }
1688 {
1690 {
1694 }
1695 else
1701 elt--;
1702 }
1706 }
1708 /* ... fall through ... */
1714 gnu_result
1721 /* For 'Code_Address, find an inner ADDR_EXPR and mark it so that we
1722 don't try to build a trampoline. */
1724 {
1729 }
1731 /* For 'Access, issue an error message if the prefix is a C++ method
1732 since it can use a special calling convention on some platforms,
1733 which cannot be propagated to the access type. */
1738 gnat_node);
1740 /* For other address attributes applied to a nested function,
1741 find an inner ADDR_EXPR and annotate it so that we can issue
1742 a useful warning with -Wtrampolines. */
1744 {
1749 {
1752 /* Also check the inlining status. */
1755 /* Check that we're not violating the No_Implicit_Dynamic_Code
1756 restriction. Be conservative if we don't know anything
1757 about the trampoline strategy for the target. */
1759 }
1760 }
1764 {
1766 tree gnu_obj_type;
1770 /* If this is fat pointer, the object must have been allocated with the
1771 template in front of the array. So compute the template address; do
1772 it by converting to a thin pointer. */
1774 gnu_ptr
1776 (TYPE_OBJECT_RECORD_TYPE
1778 gnu_ptr);
1782 /* If this is a thin pointer, the object must have been allocated with
1783 the template in front of the array. So compute the template address
1784 and return it. */
1786 gnu_ptr
1788 gnu_ptr,
1790 byte_position
1791 (DECL_CHAIN
1795 }
1804 /* Remove NOPs and conversions between original and packable version
1805 from GNU_EXPR, and conversions from GNU_PREFIX. We use GNU_EXPR
1806 to see if a COMPONENT_REF was involved. */
1811 == RECORD_TYPE
1820 /* Replace an unconstrained array type with the type of the underlying
1821 array. We can't do this with a call to maybe_unconstrained_array
1822 since we may have a TYPE_DECL. For 'Max_Size_In_Storage_Elements,
1823 use the record type that will be used to allocate the object and its
1824 template. */
1826 {
1830 }
1832 /* If we're looking for the size of a field, return the field size. */
1836 /* Otherwise, if the prefix is an object, or if we are looking for
1837 'Object_Size or 'Max_Size_In_Storage_Elements, the result is the
1838 GCC size of the type. We make an exception for padded objects,
1839 as we do not take into account alignment promotions for the size.
1840 This is in keeping with the object case of gnat_to_gnu_entity. */
1846 {
1847 /* If this is a dereference and we have a special dynamic constrained
1848 subtype on the prefix, use it to compute the size; otherwise, use
1849 the designated subtype. */
1851 {
1852 Node_Id gnat_actual_subtype
1854 tree gnu_ptr_type
1859 {
1860 tree gnu_actual_obj_type
1862 gnu_type
1864 gnu_actual_obj_type,
1867 }
1868 }
1871 }
1873 /* Otherwise, the result is the RM size of the type. */
1874 else
1877 /* Deal with a self-referential size by returning the maximum size for
1878 a type and by qualifying the size with the object otherwise. */
1880 {
1883 else
1885 }
1887 /* If the type contains a template, subtract its size. */
1893 /* For 'Max_Size_In_Storage_Elements, adjust the unit. */
1901 {
1914 else
1915 {
1920 /* If the default alignment of "double" or larger scalar types is
1921 specifically capped and there is an alignment clause neither
1922 on the type nor on the prefix itself, return the cap. */
1924 is_capped_double
1927 is_capped_double
1929 else
1939 else
1941 }
1944 }
1953 {
1960 else
1963 }
1965 /* ... fall through ... */
1968 {
1976 /* Make sure any implicit dereference gets done. */
1980 /* We treat unconstrained array In parameters specially. We also note
1981 whether we are dereferencing a pointer to unconstrained array. */
1984 {
1986 /* This is the direct case. */
1992 /* This is the indirect case. Note that we need to be sure that
1993 the access value cannot be null as we'll hoist the load. */
1996 {
1999 }
2000 else
2006 }
2008 /* If the prefix is the view conversion of a constrained array to an
2009 unconstrained form, we retrieve the constrained array because we
2010 might not be able to substitute the PLACEHOLDER_EXPR coming from
2011 the conversion. This can occur with the 'Old attribute applied
2012 to a parameter with an unconstrained type, which gets rewritten
2013 into a constrained local variable very late in the game. */
2016 && !CONTAINS_PLACEHOLDER_P
2019 else
2026 {
2028 tree gnu_type_temp;
2034 ;
2037 }
2044 /* When not optimizing, look up the slot associated with the parameter
2045 and the dimension in the cache and create a new one on failure.
2046 Don't do this when the actual subtype needs debug info (this happens
2047 with -gnatD): in elaborate_expression_1, we create variables that
2048 hold the bounds, so caching attributes isn't very interesting and
2049 causes dependency issues between these variables and cached
2050 expressions. */
2055 {
2061 {
2066 }
2067 }
2069 /* Return the cached expression or build a new one. */
2071 {
2073 {
2076 }
2078 gnu_result
2080 }
2083 {
2085 {
2088 }
2090 gnu_result
2092 }
2095 {
2097 {
2100 }
2102 gnu_result
2104 gnu_result_type);
2105 }
2107 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2108 handling. Note that these attributes could not have been used on
2109 an unconstrained array type. */
2112 /* Cache the expression we have just computed. Since we want to do it
2113 at run time, we force the use of a SAVE_EXPR and let the gimplifier
2114 create the temporary in the outermost binding level. We will make
2115 sure in Subprogram_Body_to_gnu that it is evaluated on all possible
2116 paths by forcing its evaluation on entry of the function. */
2118 {
2119 gnu_result
2122 {
2138 }
2139 }
2141 /* Otherwise, evaluate it each time it is referenced. */
2142 else
2144 {
2147 /* If we are dereferencing a pointer to unconstrained array, we
2148 need to capture the value because the pointed-to bounds may
2149 subsequently be released. */
2151 gnu_result
2157 /* Set the source location onto the predicate of the condition
2158 but not if the expression is cached to avoid messing up the
2159 debug info. */
2163 gnat_node);
2168 }
2171 }
2178 {
2179 HOST_WIDE_INT bitsize;
2180 HOST_WIDE_INT bitpos;
2181 tree gnu_offset;
2182 tree gnu_field_bitpos;
2183 tree gnu_field_offset;
2184 tree gnu_inner;
2185 machine_mode mode;
2192 /* We can have 'Bit on any object, but if it isn't a COMPONENT_REF,
2193 the result is 0. Don't allow 'Bit on a bare component, though. */
2197 {
2200 }
2202 else
2211 {
2219 {
2220 gnu_field_bitpos
2223 gnu_field_offset
2226 }
2227 }
2229 {
2232 }
2233 else
2234 {
2237 }
2240 {
2254 /* ??? Avoid a large unsigned result that will overflow when
2255 converted to the signed universal_integer. */
2258 else
2259 gnu_result
2266 }
2268 /* If this has a PLACEHOLDER_EXPR, qualify it by the object we are
2269 handling. */
2272 }
2276 {
2282 /* The result of {MIN,MAX}_EXPR is unspecified if either operand is
2283 a NaN so we implement the semantics of C99 f{min,max} to make it
2284 predictable in this case: if either operand is a NaN, the other
2285 is returned; if both operands are NaN's, a NaN is returned. */
2288 {
2294 /* If the operands have side-effects, they need to be evaluated
2295 only once in spite of the multiple references in the result. */
2303 integer_zero_node);
2307 integer_zero_node);
2317 /* If the operands have side-effects, they need to be evaluated
2318 before doing the tests above since the place they otherwise
2319 would end up being evaluated at run time could be wrong. */
2321 gnu_result
2325 gnu_result
2327 }
2328 else
2332 }
2358 /* Note this size cannot be self-referential. */
2368 /* What we want is the offset of the ARRAY field in the record
2369 that the thin pointer designates. */
2377 /* This is just a zero cast to the pointer type for our prefix and
2378 dereferenced. */
2380 gnu_result
2383 integer_zero_node));
2388 {
2395 {
2400 ;
2401 }
2409 && (DECL_BY_COMPONENT_PTR_P
2413 }
2417 /* We treat Model as identical to Machine. This is true for at least
2418 IEEE and some other nice floating-point systems. */
2420 /* ... fall through ... */
2423 /* The trick is to force the compiler to store the result in memory so
2424 that we do not have extra precision used. But do this only when this
2425 is necessary, i.e. if FP_ARITH_MAY_WIDEN is true and the precision of
2426 the type is lower than that of the longest floating-point type. */
2433 && fp_arith_may_widen
2436 {
2438 tree field
2448 asm_expr
2460 gnu_result
2464 }
2471 /* This can be a random address so build an alias-all pointer type. */
2472 gnu_expr
2475 gnu_expr);
2480 /* This abort means that we have an unimplemented attribute. */
2482 }
2484 /* If this is an attribute where the prefix was unused, force a use of it if
2485 it has a side-effect. But don't do it if the prefix is just an entity
2486 name. However, if an access check is needed, we must do it. See second
2487 example in AARM 11.6(5.e). */
2491 gnu_result
2496 }
2497 \f
2498 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Case_Statement,
2499 to a GCC tree, which is returned. */
2501 static tree
2503 {
2505 Node_Id gnat_when;
2506 location_t end_locus;
2512 /* The range of values in a case statement is determined by the rules in
2513 RM 5.4(7-9). In almost all cases, this range is represented by the Etype
2514 of the expression. One exception arises in the case of a simple name that
2515 is parenthesized. This still has the Etype of the name, but since it is
2516 not a name, para 7 does not apply, and we need to go to the base type.
2517 This is the only case where parenthesization affects the dynamic
2518 semantics (i.e. the range of possible values at run time that is covered
2519 by the others alternative).
2521 Another exception is if the subtype of the expression is non-static. In
2522 that case, we also have to use the base type. */
2528 /* We build a SWITCH_EXPR that contains the code with interspersed
2529 CASE_LABEL_EXPRs for each label. */
2538 {
2540 Node_Id gnat_choice;
2542 /* First compile all the different case choices for the current WHEN
2543 alternative. */
2547 {
2552 {
2567 /* This represents either a subtype range or a static value of
2568 some kind; Ekind says which. */
2570 {
2576 }
2578 /* ... fall through ... */
2590 }
2592 /* Everything should be folded into constants at this point. */
2597 gnat_choice);
2599 }
2601 /* This construct doesn't define a scope so we shouldn't push a binding
2602 level around the statement list. Except that we have always done so
2603 historically and this makes it possible to reduce stack usage. As a
2604 compromise, we keep doing it for case statements, for which this has
2605 never been problematic, but not for case expressions in Ada 2012. */
2607 {
2608 const bool is_case_expression
2610 tree group
2615 {
2620 }
2621 }
2622 }
2624 /* Now emit a definition of the label the cases branch to, if any. */
2631 }
2632 \f
2633 /* Return true if we are in the body of a loop. */
2637 {
2639 }
2641 /* Find out whether VAR is the iteration variable of an enclosing loop in the
2642 current function. If so, return the loop; otherwise, return NULL. */
2646 {
2665 }
2667 /* Return true if VAL (of type TYPE) can equal the minimum value if MAX is
2668 false, or the maximum value if MAX is true, of TYPE. */
2670 static bool
2672 {
2679 val = (max
2688 else
2690 }
2692 /* Return true if VAL (of type TYPE) can equal the minimum value of TYPE.
2693 If REVERSE is true, minimum value is taken as maximum value. */
2697 {
2699 }
2701 /* Return true if VAL (of type TYPE) can equal the maximum value of TYPE.
2702 If REVERSE is true, maximum value is taken as minimum value. */
2706 {
2708 }
2710 /* Return true if VAL1 can be lower than VAL2. */
2712 static bool
2714 {
2728 }
2730 /* Replace EXPR1 and EXPR2 by invariant expressions if possible. Return
2731 true if both expressions have been replaced and false otherwise. */
2733 static bool
2735 {
2746 }
2748 /* Helper function for walk_tree, used by independent_iterations_p below. */
2750 static tree
2752 {
2756 /* No need to walk into types or decls. */
2764 }
2766 /* Return true if STMT_LIST generates independent iterations in a loop. */
2768 static bool
2770 {
2771 tree_stmt_iterator tsi;
2774 tree iter;
2780 /* Scan the list and return false on anything that is not either a check
2781 or an assignment to a parameter with restricted aliasing. */
2783 {
2787 {
2789 {
2798 }
2801 {
2814 }
2818 }
2819 }
2821 /* At this point we know that the list contains only statements that will
2822 modify parameters with restricted aliasing. Check that the statements
2823 don't at the time read from these parameters. */
2829 }
2831 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Loop_Statement,
2832 to a GCC tree, which is returned. */
2834 static tree
2836 {
2843 tree gnu_result;
2845 /* Push the loop_info structure associated with the LOOP_STMT. */
2848 /* Set location information for statement and end label. */
2854 /* Save the statement for later reuse. */
2858 /* Set the condition under which the loop must keep going.
2859 For the case "LOOP .... END LOOP;" the condition is always true. */
2861 ;
2863 /* For the case "WHILE condition LOOP ..... END LOOP;" it's immediate. */
2868 /* Otherwise we have an iteration scheme and the condition is given by the
2869 bounds of the subtype of the iteration variable. */
2870 else
2871 {
2885 /* We must disable modulo reduction for the iteration variable, if any,
2886 in order for the loop comparison to be effective. */
2888 {
2894 }
2895 else
2896 {
2902 }
2904 /* We use two different strategies to translate the loop, depending on
2905 whether optimization is enabled.
2907 If it is, we generate the canonical loop form expected by the loop
2908 optimizer and the loop vectorizer, which is the do-while form:
2910 ENTRY_COND
2911 loop:
2912 TOP_UPDATE
2913 BODY
2914 BOTTOM_COND
2915 GOTO loop
2917 This avoids an implicit dependency on loop header copying and makes
2918 it possible to turn BOTTOM_COND into an inequality test.
2920 If optimization is disabled, loop header copying doesn't come into
2921 play and we try to generate the loop form with the fewer conditional
2922 branches. First, the default form, which is:
2924 loop:
2925 TOP_COND
2926 BODY
2927 BOTTOM_UPDATE
2928 GOTO loop
2930 It should catch most loops with constant ending point. Then, if we
2931 cannot, we try to generate the shifted form:
2933 loop:
2934 TOP_COND
2935 TOP_UPDATE
2936 BODY
2937 GOTO loop
2939 which should catch loops with constant starting point. Otherwise, if
2940 we cannot, we generate the fallback form:
2942 ENTRY_COND
2943 loop:
2944 BODY
2945 BOTTOM_COND
2946 BOTTOM_UPDATE
2947 GOTO loop
2949 which works in all cases. */
2952 {
2953 /* We can use the do-while form directly if GNU_FIRST-1 doesn't
2954 overflow. */
2956 ;
2958 /* Otherwise, use the do-while form with the help of a special
2959 induction variable in the unsigned version of the base type
2960 or the unsigned version of the size type, whichever is the
2961 largest, in order to have wrap-around arithmetics for it. */
2962 else
2963 {
2966 gnu_base_type
2968 else
2975 }
2977 gnu_first
2979 gnu_one_node);
2982 }
2983 else
2984 {
2985 /* We can use the default form if GNU_LAST+1 doesn't overflow. */
2987 ;
2989 /* Otherwise, we can use the shifted form if neither GNU_FIRST-1 nor
2990 GNU_LAST-1 does. */
2993 {
2994 gnu_first
2996 gnu_one_node);
2997 gnu_last
2999 gnu_one_node);
3001 }
3003 /* Otherwise, use the fallback form. */
3004 else
3006 }
3008 /* If we use the BOTTOM_COND, we can turn the test into an inequality
3009 test but we may have to add ENTRY_COND to protect the empty loop. */
3011 {
3014 {
3015 gnu_cond_expr
3021 }
3022 }
3024 /* Open a new nesting level that will surround the loop to declare the
3025 iteration variable. */
3029 /* If we use the special induction variable, create it and set it to
3030 its initial value. Morever, the regular iteration variable cannot
3031 itself be initialized, lest the initial value wrapped around. */
3033 {
3034 gnu_loop_iv
3038 }
3039 else
3042 /* Declare the iteration variable and set it to its initial value. */
3047 {
3050 }
3055 /* Do all the arithmetics in the base type. */
3058 /* Set either the top or bottom exit condition. */
3062 gnu_last);
3063 else
3066 gnu_last);
3068 /* Set either the top or bottom update statement and give it the source
3069 location of the iteration for better coverage info. */
3071 {
3072 gnu_stmt
3079 gnu_stmt
3081 gnu_loop_iv);
3085 }
3086 else
3087 {
3088 gnu_stmt
3094 }
3095 }
3097 /* If the loop was named, have the name point to this loop. In this case,
3098 the association is not a DECL node, but the end label of the loop. */
3102 /* Make the loop body into its own block, so any allocated storage will be
3103 released every iteration. This is needed for stack allocation. */
3108 /* If we have an iteration scheme, then we are in a statement group. Add
3109 the LOOP_STMT to it, finish it and make it the "loop". */
3111 {
3112 /* First, if we have computed invariant conditions for range (or index)
3113 checks applied to the iteration variable, find out whether they can
3114 be evaluated to false at compile time; otherwise, if there are not
3115 too many of them, combine them with the original checks. If loop
3116 unswitching is enabled, do not require the loop bounds to be also
3117 invariant, as their evaluation will still be ahead of the loop. */
3120 {
3125 {
3126 tree low_ok
3133 tree high_ok
3140 tree range_ok
3144 rci->invariant_cond
3149 else
3150 n_remaining_checks++;
3151 }
3153 /* Note that loop unswitching can only be applied a small number of
3154 times to a given loop (PARAM_MAX_UNSWITCH_LEVEL default to 3). */
3159 {
3164 }
3165 }
3167 /* Second, if loop vectorization is enabled and the iterations of the
3168 loop can easily be proved as independent, mark the loop. */
3170 && flag_tree_loop_vectorize
3177 }
3179 /* If we have an outer COND_EXPR, that's our result and this loop is its
3180 "true" statement. Otherwise, the result is the LOOP_STMT. */
3182 {
3186 }
3187 else
3193 }
3194 \f
3195 /* This page implements a form of Named Return Value optimization modelled
3196 on the C++ optimization of the same name. The main difference is that
3197 we disregard any semantical considerations when applying it here, the
3198 counterpart being that we don't try to apply it to semantically loaded
3199 return types, i.e. types with the TYPE_BY_REFERENCE_P flag set.
3201 We consider a function body of the following GENERIC form:
3203 return_type R1;
3204 [...]
3205 RETURN_EXPR [<retval> = ...]
3206 [...]
3207 RETURN_EXPR [<retval> = R1]
3208 [...]
3209 return_type Ri;
3210 [...]
3211 RETURN_EXPR [<retval> = ...]
3212 [...]
3213 RETURN_EXPR [<retval> = Ri]
3214 [...]
3216 and we try to fulfill a simple criterion that would make it possible to
3217 replace one or several Ri variables with the RESULT_DECL of the function.
3219 The first observation is that RETURN_EXPRs that don't directly reference
3220 any of the Ri variables on the RHS of their assignment are transparent wrt
3221 the optimization. This is because the Ri variables aren't addressable so
3222 any transformation applied to them doesn't affect the RHS; moreover, the
3223 assignment writes the full <retval> object so existing values are entirely
3224 discarded.
3226 This property can be extended to some forms of RETURN_EXPRs that reference
3227 the Ri variables, for example CONSTRUCTORs, but isn't true in the general
3228 case, in particular when function calls are involved.
3230 Therefore the algorithm is as follows:
3232 1. Collect the list of candidates for a Named Return Value (Ri variables
3233 on the RHS of assignments of RETURN_EXPRs) as well as the list of the
3234 other expressions on the RHS of such assignments.
3236 2. Prune the members of the first list (candidates) that are referenced
3237 by a member of the second list (expressions).
3239 3. Extract a set of candidates with non-overlapping live ranges from the
3240 first list. These are the Named Return Values.
3242 4. Adjust the relevant RETURN_EXPRs and replace the occurrences of the
3243 Named Return Values in the function with the RESULT_DECL.
3245 If the function returns an unconstrained type, things are a bit different
3246 because the anonymous return object is allocated on the secondary stack
3247 and RESULT_DECL is only a pointer to it. Each return object can be of a
3248 different size and is allocated separately so we need not care about the
3249 aforementioned overlapping issues. Therefore, we don't collect the other
3250 expressions and skip step #2 in the algorithm. */
3252 struct nrv_data
3253 {
3254 bitmap nrv;
3255 tree result;
3256 Node_Id gnat_ret;
3258 };
3260 /* Return true if T is a Named Return Value. */
3264 {
3266 }
3268 /* Helper function for walk_tree, used by finalize_nrv below. */
3270 static tree
3272 {
3276 /* No need to walk into types or decls. */
3284 }
3286 /* Prune Named Return Values in BLOCK and return true if there is still a
3287 Named Return Value in BLOCK or one of its sub-blocks. */
3289 static bool
3291 {
3293 tree t;
3295 /* First recurse on the sub-blocks. */
3299 /* Then make sure to keep at most one NRV per block. */
3302 {
3305 else
3307 }
3310 }
3312 /* Helper function for walk_tree, used by finalize_nrv below. */
3314 static tree
3316 {
3320 /* No need to walk into types. */
3324 /* Change RETURN_EXPRs of NRVs to just refer to the RESULT_DECL; this is a
3325 nop, but differs from using NULL_TREE in that it indicates that we care
3326 about the value of the RESULT_DECL. */
3329 {
3332 /* If this is the temporary created for a return value with variable
3333 size in Call_to_gnu, we replace the RHS with the init expression. */
3338 {
3341 }
3342 else
3345 /* Strip useless conversions around the return value. */
3350 {
3353 else
3355 }
3356 }
3358 /* Replace the DECL_EXPR of NRVs with an initialization of the RESULT_DECL,
3359 if needed. */
3362 {
3366 {
3371 }
3372 else
3376 /* Identify the NRV to the RESULT_DECL for debugging purposes. */
3379 /* ??? Kludge to avoid an assertion failure during inlining. */
3382 }
3384 /* And replace all uses of NRVs with the RESULT_DECL. */
3388 /* Avoid walking into the same tree more than once. Unfortunately, we
3389 can't just use walk_tree_without_duplicates because it would only
3390 call us for the first occurrence of NRVs in the function body. */
3395 }
3397 /* Likewise, but used when the function returns an unconstrained type. */
3399 static tree
3401 {
3405 /* No need to walk into types. */
3409 /* We need to see the DECL_EXPR of NRVs before any other references so we
3410 walk the body of BIND_EXPR before walking its variables. */
3414 /* Change RETURN_EXPRs of NRVs to assign to the RESULT_DECL only the final
3415 return value built by the allocator instead of the whole construct. */
3418 {
3421 /* This is the construct returned by the allocator. */
3424 {
3429 else
3431 }
3433 /* Strip useless conversions around the return value. */
3438 /* Strip unpadding around the return value. */
3443 /* Assign the new return value to the RESULT_DECL. */
3447 }
3449 /* Adjust the DECL_EXPR of NRVs to call the allocator and save the result
3450 into a new variable. */
3453 {
3460 /* Create an artificial context to build the allocation. */
3465 /* This will return a COMPOUND_EXPR with the allocation in the first
3466 arm and the final return value in the second arm. */
3473 /* The new variable is built as a reference to the allocated space. */
3474 new_var
3480 {
3483 /* The new initial value is a COMPOUND_EXPR with the allocation in
3484 the first arm and the value of P_ARRAY in the second arm. */
3490 /* Build a modified CONSTRUCTOR that references NEW_VAR. */
3497 }
3498 else
3499 {
3500 /* The new initial value is just the allocation. */
3503 }
3507 /* Destroy the artificial context and insert the new statements. */
3512 /* Chain NEW_VAR immediately after VAR and ignore the latter. */
3517 /* Save the new return value and the dereference of NEW_VAR. */
3521 /* ??? Kludge to avoid messing up during inlining. */
3523 }
3525 /* And replace all uses of NRVs with the dereference of NEW_VAR. */
3529 /* Avoid walking into the same tree more than once. Unfortunately, we
3530 can't just use walk_tree_without_duplicates because it would only
3531 call us for the first occurrence of NRVs in the function body. */
3536 }
3538 /* Finalize the Named Return Value optimization for FNDECL. The NRV bitmap
3539 contains the candidates for Named Return Value and OTHER is a list of
3540 the other return values. GNAT_RET is a representative return node. */
3542 static void
3544 {
3547 walk_tree_fn func;
3549 tree iter;
3551 /* We shouldn't be applying the optimization to return types that we aren't
3552 allowed to manipulate freely. */
3555 /* Prune the candidates that are referenced by other return values. */
3565 /* Prune also the candidates that are referenced by nested functions. */
3573 /* Extract a set of NRVs with non-overlapping live ranges. */
3577 /* Adjust the relevant RETURN_EXPRs and replace the occurrences of NRVs. */
3584 else
3588 }
3590 /* Return true if RET_VAL can be used as a Named Return Value for the
3591 anonymous return object RET_OBJ. */
3593 static bool
3595 {
3615 }
3617 /* Build a RETURN_EXPR. If RET_VAL is non-null, build a RETURN_EXPR around
3618 the assignment of RET_VAL to RET_OBJ. Otherwise build a bare RETURN_EXPR
3619 around RESULT_OBJ, which may be null in this case. */
3621 static tree
3623 {
3624 tree result_expr;
3627 {
3628 /* The gimplifier explicitly enforces the following invariant:
3630 RETURN_EXPR
3631 |
3632 INIT_EXPR
3633 / \
3634 / \
3635 RET_OBJ ...
3637 As a consequence, type consistency dictates that we use the type
3638 of the RET_OBJ as the operation type. */
3641 /* Convert the right operand to the operation type. Note that this is
3642 the transformation applied in the INIT_EXPR case of build_binary_op,
3643 with the assumption that the type cannot involve a placeholder. */
3647 /* We always can use an INIT_EXPR for the return object. */
3650 /* If the function returns an aggregate type, find out whether this is
3651 a candidate for Named Return Value. If so, record it. Otherwise,
3652 if this is an expression of some kind, record it elsewhere. */
3658 {
3659 /* Recognize the temporary created for a return value with variable
3660 size in Call_to_gnu. We want to eliminate it if possible. */
3667 /* Strip useless conversions around the return value. */
3671 /* Now apply the test to the return value. */
3673 {
3677 }
3679 /* Note that we need not care about CONSTRUCTORs here, as they are
3680 totally transparent given the read-compose-write semantics of
3681 assignments from CONSTRUCTORs. */
3684 }
3685 }
3686 else
3690 }
3691 \f
3692 /* Subroutine of gnat_to_gnu to process gnat_node, an N_Subprogram_Body. We
3693 don't return anything. */
3695 static void
3697 {
3698 /* Defining identifier of a parameter to the subprogram. */
3699 Entity_Id gnat_param;
3700 /* The defining identifier for the subprogram body. Note that if a
3701 specification has appeared before for this body, then the identifier
3702 occurring in that specification will also be a defining identifier and all
3703 the calls to this subprogram will point to that specification. */
3704 Entity_Id gnat_subprog_id
3707 /* The FUNCTION_DECL node corresponding to the subprogram spec. */
3708 tree gnu_subprog_decl;
3709 /* Its RESULT_DECL node. */
3710 tree gnu_result_decl;
3711 /* Its FUNCTION_TYPE node. */
3712 tree gnu_subprog_type;
3713 /* The TYPE_CI_CO_LIST of its FUNCTION_TYPE node, if any. */
3714 tree gnu_cico_list;
3715 /* The entry in the CI_CO_LIST that represents a function return, if any. */
3717 tree gnu_result;
3718 location_t locus;
3722 /* If this is a generic object or if it has been eliminated,
3723 ignore it. */
3729 /* If this subprogram acts as its own spec, define it. Otherwise, just get
3730 the already-elaborated tree node. However, if this subprogram had its
3731 elaboration deferred, we will already have made a tree node for it. So
3732 treat it as not being defined in that case. Such a subprogram cannot
3733 have an address clause or a freeze node, so this test is safe, though it
3734 does disable some otherwise-useful error checking. */
3735 gnu_subprog_decl
3745 /* If the function returns by invisible reference, make it explicit in the
3746 function body. See gnat_to_gnu_entity, E_Subprogram_Type case. */
3748 {
3752 }
3754 /* Set the line number in the decl to correspond to that of the body. */
3758 /* Initialize the information structure for the function. */
3767 /* If there are copy-in/copy-out parameters, we need to ensure that they are
3768 properly copied out by the return statement. We do this by making a new
3769 block and converting any return into a goto to a label at the end of the
3770 block. */
3772 {
3781 /* If this is a function with copy-in/copy-out parameters and which does
3782 not return by invisible reference, we also need a variable for the
3783 return value to be placed. */
3785 {
3786 tree gnu_return_type
3789 gnu_return_var
3795 }
3799 /* See whether there are parameters for which we don't have a GCC tree
3800 yet. These must be Out parameters. Make a VAR_DECL for them and
3801 put it into TYPE_CI_CO_LIST, which must contain an empty entry too.
3802 We can match up the entries because TYPE_CI_CO_LIST is in the order
3803 of the parameters. */
3808 {
3810 tree gnu_decl;
3812 /* Skip any entries that have been already filled in; they must
3813 correspond to In Out parameters. */
3817 /* Do any needed dereferences for by-ref objects. */
3823 /* Do any needed references for padded types. */
3826 }
3827 }
3828 else
3831 /* Get a tree corresponding to the code for the subprogram. */
3837 /* Generate the code of the subprogram itself. A return statement will be
3838 present and any Out parameters will be handled there. */
3843 /* If we populated the parameter attributes cache, we need to make sure that
3844 the cached expressions are evaluated on all the possible paths leading to
3845 their uses. So we force their evaluation on entry of the function. */
3848 {
3855 {
3862 }
3868 }
3870 /* If we are dealing with a return from an Ada procedure with parameters
3871 passed by copy-in/copy-out, we need to return a record containing the
3872 final values of these parameters. If the list contains only one entry,
3873 return just that entry though.
3875 For a full description of the copy-in/copy-out parameter mechanism, see
3876 the part of the gnat_to_gnu_entity routine dealing with the translation
3877 of subprograms.
3879 We need to make a block that contains the definition of that label and
3880 the copying of the return value. It first contains the function, then
3881 the label and copy statement. */
3883 {
3884 const Node_Id gnat_end_label
3893 /* If this is a function which returns by invisible reference, the
3894 return value has already been dealt with at the return statements,
3895 so we only need to indirectly copy out the parameters. */
3897 {
3898 tree gnu_ret_deref
3900 tree t;
3905 {
3906 tree gnu_field_deref
3911 }
3912 }
3914 /* Otherwise, if this is a procedure or a function which does not return
3915 by invisible reference, we can do a direct block-copy out. */
3916 else
3917 {
3918 tree gnu_retval;
3922 else
3923 gnu_retval
3925 gnu_cico_list);
3929 }
3933 }
3937 /* Attempt setting the end_locus of our GCC body tree, typically a
3938 BIND_EXPR or STATEMENT_LIST, then the end_locus of our GCC subprogram
3939 declaration tree. */
3943 /* On SEH targets, install an exception handler around the main entry
3944 point to catch unhandled exceptions. */
3947 {
3948 tree t;
3949 tree etype;
3961 }
3965 /* Finally annotate the parameters and disconnect the trees for parameters
3966 that we have turned into variables since they are now unusable. */
3970 {
3979 }
3981 /* Disconnect the variable created for the return value. */
3985 /* If the function returns an aggregate type and we have candidates for
3986 a Named Return Value, finalize the optimization. */
3988 {
3995 }
3997 /* If this is an inlined external function that has been marked uninlinable,
3998 drop the body and stop there. Otherwise compile the body. */
4001 else
4003 }
4004 \f
4005 /* Return true if GNAT_NODE references an Atomic entity. */
4007 static bool
4009 {
4010 Entity_Id gnat_entity;
4013 {
4029 /* ... fall through ... */
4036 }
4039 }
4041 /* Return true if GNAT_NODE references a Volatile_Full_Access entity. */
4043 static bool
4045 {
4046 Entity_Id gnat_entity;
4049 {
4069 }
4072 }
4074 /* Strip any type conversion on GNAT_NODE and return the result. */
4076 static Node_Id
4078 {
4085 }
4087 /* Return true if GNAT_NODE requires outer atomic access, i.e. atomic access
4088 of an object of which GNAT_NODE is a component. */
4090 static bool
4092 {
4096 {
4098 {
4103 gnat_node
4117 }
4118 }
4121 }
4123 /* Return true if GNAT_NODE requires atomic access and set SYNC according to
4124 the associated synchronization setting. */
4126 static bool
4128 {
4133 /* First, scan the parent to find out cases where the flag is irrelevant. */
4135 {
4138 /* Do not mess up machine code insertions. */
4142 /* Nothing to do if we are the prefix of an attribute, since we do not
4143 want an atomic access for things like 'Size. */
4145 /* ... fall through ... */
4148 /* The N_Reference node is like an attribute. */
4156 /* If we are the prefix, then the access is only partial. */
4162 /* Nothing to do for the identifier in an object renaming declaration,
4163 the renaming itself does not need atomic access. */
4168 }
4170 /* Then, scan the node to find the atomic object. */
4173 /* For Atomic itself, only reads and updates of the object as a whole require
4174 atomic access (RM C.6 (15)). But for Volatile_Full_Access, all reads and
4175 updates require atomic access. */
4180 /* If an outer atomic access will also be required, it cancels this one. */
4187 }
4188 \f
4189 /* Create a temporary variable with PREFIX and TYPE, and return it. */
4191 static tree
4193 {
4198 }
4200 /* Create a temporary variable with PREFIX and initialize it with GNU_INIT.
4201 Put the initialization statement into GNU_INIT_STMT and annotate it with
4202 the SLOC of GNAT_NODE. Return the temporary variable. */
4204 static tree
4206 Node_Id gnat_node)
4207 {
4214 }
4216 /* Subroutine of gnat_to_gnu to translate gnat_node, either an N_Function_Call
4217 or an N_Procedure_Call_Statement, to a GCC tree, which is returned.
4218 GNU_RESULT_TYPE_P is a pointer to where we should place the result type.
4219 If GNU_TARGET is non-null, this must be a function call on the RHS of a
4220 N_Assignment_Statement and the result is to be placed into that object.
4221 If OUTER_ATOMIC_ACCESS is true, then the assignment to GNU_TARGET must be a
4222 load-modify-store sequence. Otherwise, if ATOMIC_ACCESS is true, then the
4223 assignment to GNU_TARGET must be atomic. If, in addition, ATOMIC_SYNC is
4224 true, then the assignment to GNU_TARGET requires atomic synchronization. */
4226 static tree
4229 {
4232 /* The GCC node corresponding to the GNAT subprogram name. This can either
4233 be a FUNCTION_DECL node if we are dealing with a standard subprogram call,
4234 or an indirect reference expression (an INDIRECT_REF node) pointing to a
4235 subprogram. */
4237 /* The FUNCTION_TYPE node giving the GCC type of the subprogram. */
4239 /* The return type of the FUNCTION_TYPE. */
4250 Entity_Id gnat_formal;
4251 Node_Id gnat_actual;
4256 /* If we are calling a stubbed function, raise Program_Error, but Elaborate
4257 all our args first. */
4259 {
4269 {
4272 }
4275 }
4277 /* For a call to a nested function, check the inlining status. */
4282 /* The only way we can be making a call via an access type is if Name is an
4283 explicit dereference. In that case, get the list of formal args from the
4284 type the access type is pointing to. Otherwise, get the formals from the
4285 entity being called. */
4289 /* Assume here that this must be 'Elab_Body or 'Elab_Spec. */
4291 else
4294 /* The lifetime of the temporaries created for the call ends right after the
4295 return value is copied, so we can give them the scope of the elaboration
4296 routine at top level. */
4298 {
4301 }
4303 /* First, create the temporary for the return value when:
4305 1. There is no target and the function has copy-in/copy-out parameters,
4306 because we need to preserve the return value before copying back the
4307 parameters.
4309 2. There is no target and this is neither an object nor a renaming
4310 declaration, and the return type has variable size, because in
4311 these cases the gimplifier cannot create the temporary.
4313 3. There is a target and it is a slice or an array with fixed size,
4314 and the return type has variable size, because the gimplifier
4315 doesn't handle these cases.
4317 This must be done before we push a binding level around the call, since
4318 we will pop it before copying the return value. */
4321 || (!gnu_target
4325 || (gnu_target
4333 /* Create the list of the actual parameters as GCC expects it, namely a
4334 chain of TREE_LIST nodes in which the TREE_VALUE field of each node
4335 is an expression and the TREE_PURPOSE field is null. But skip Out
4336 parameters not passed by reference and that need not be copied in. */
4341 {
4346 const bool is_true_formal_parm
4348 const bool is_by_ref_formal_parm
4349 = is_true_formal_parm
4352 /* In the Out or In Out case, we must suppress conversions that yield
4353 an lvalue but can nevertheless cause the creation of a temporary,
4354 because we need the real object in this case, either to pass its
4355 address if it's passed by reference or as target of the back copy
4356 done after the call if it uses the copy-in/copy-out mechanism.
4357 We do it in the In case too, except for an unchecked conversion
4358 to an elementary type or a constrained composite type because it
4359 alone can cause the actual to be misaligned and the addressability
4360 test is applied to the real object. */
4361 const bool suppress_type_conversion
4368 Node_Id gnat_name = suppress_type_conversion
4371 tree gnu_actual;
4373 /* If it's possible we may need to use this expression twice, make sure
4374 that any side-effects are handled via SAVE_EXPRs; likewise if we need
4375 to force side-effects before the call. */
4377 && !is_by_ref_formal_parm
4379 {
4383 gnu_name
4385 }
4387 /* If we are passing a non-addressable parameter by reference, pass the
4388 address of a copy. In the Out or In Out case, set up to copy back
4389 out after the call. */
4393 {
4397 /* Do not issue warnings for CONSTRUCTORs since this is not a copy
4398 but sort of an instantiation for them. */
4400 ;
4402 /* If the type is passed by reference, a copy is not allowed. */
4405 gnat_actual);
4407 /* For users of Starlet we issue a warning because the interface
4408 apparently assumes that by-ref parameters outlive the procedure
4409 invocation. The code still will not work as intended, but we
4410 cannot do much better since low-level parts of the back-end
4411 would allocate temporaries at will because of the misalignment
4412 if we did not do so here. */
4414 {
4415 post_error
4417 post_error_ne
4421 gnat_formal);
4422 }
4424 /* If the actual type of the object is already the nominal type,
4425 we have nothing to do, except if the size is self-referential
4426 in which case we'll remove the unpadding below. */
4429 ;
4431 /* Otherwise remove the unpadding from all the objects. */
4433 && TYPE_IS_PADDING_P
4437 /* Otherwise convert to the nominal type of the object if needed.
4438 There are several cases in which we need to make the temporary
4439 using this type instead of the actual type of the object when
4440 they are distinct, because the expectations of the callee would
4441 otherwise not be met:
4442 - if it's a justified modular type,
4443 - if the actual type is a smaller form of it,
4444 - if it's a smaller form of the actual type. */
4448 gnu_name_type)))
4454 /* If this is an In Out or Out parameter and we're returning a value,
4455 we need to create a temporary for the return value because we must
4456 preserve it before copying back at the very end. */
4460 /* If we haven't pushed a binding level, push a new one. This will
4461 narrow the lifetime of the temporary we are about to make as much
4462 as possible. The drawback is that we'd need to create a temporary
4463 for the return value, if any (see comment before the loop). So do
4464 it only when this temporary was already created just above. */
4466 {
4470 }
4472 /* Create an explicit temporary holding the copy. */
4473 gnu_temp
4476 /* But initialize it on the fly like for an implicit temporary as
4477 we aren't necessarily having a statement list. */
4479 gnu_temp);
4481 /* Set up to move the copy back to the original if needed. */
4483 {
4484 /* If the original is a COND_EXPR whose first arm isn't meant to
4485 be further used, just deal with the second arm. This is very
4486 likely the conditional expression built for a check. */
4489 && integer_zerop
4493 gnu_stmt
4498 }
4499 }
4501 /* Start from the real object and build the actual. */
4504 /* If atomic access is required for an In or In Out actual parameter,
4505 build the atomic load. */
4507 && !is_by_ref_formal_parm
4512 /* If this was a procedure call, we may not have removed any padding.
4513 So do it here for the part we will use as an input, if any. */
4516 gnu_actual
4519 /* Put back the conversion we suppressed above in the computation of the
4520 real object. And even if we didn't suppress any conversion there, we
4521 may have suppressed a conversion to the Etype of the actual earlier,
4522 since the parent is a procedure call, so put it back here. */
4525 gnu_actual
4528 else
4529 gnu_actual
4532 /* Make sure that the actual is in range of the formal's type. */
4535 gnu_actual
4538 /* Unless this is an In parameter, we must remove any justified modular
4539 building from GNU_NAME to get an lvalue. */
4544 gnu_name
4547 /* First see if the parameter is passed by reference. */
4549 {
4551 {
4552 /* In Out or Out parameters passed by reference don't use the
4553 copy-in/copy-out mechanism so the address of the real object
4554 must be passed to the function. */
4557 /* If we have a padded type, be sure we've removed padding. */
4560 gnu_actual);
4562 /* If we have the constructed subtype of an aliased object
4563 with an unconstrained nominal subtype, the type of the
4564 actual includes the template, although it is formally
4565 constrained. So we need to convert it back to the real
4566 constructed subtype to retrieve the constrained part
4567 and takes its address. */
4573 gnu_actual);
4574 }
4576 /* There is no need to convert the actual to the formal's type before
4577 taking its address. The only exception is for unconstrained array
4578 types because of the way we build fat pointers. */
4580 {
4581 /* Put back a view conversion for In Out or Out parameters. */
4584 gnu_actual);
4586 }
4588 /* The symmetry of the paths to the type of an entity is broken here
4589 since arguments don't know that they will be passed by ref. */
4592 }
4594 /* Then see if the parameter is an array passed to a foreign convention
4595 subprogram. */
4597 {
4603 {
4606 }
4608 /* Take the address of the object and convert to the proper pointer
4609 type. We'd like to actually compute the address of the beginning
4610 of the array using an ADDR_EXPR of an ARRAY_REF, but there's a
4611 possibility that the ARRAY_REF might return a constant and we'd be
4612 getting the wrong address. Neither approach is exactly correct,
4613 but this is the most likely to work in all cases. */
4615 }
4617 /* Otherwise the parameter is passed by copy. */
4618 else
4619 {
4620 tree gnu_size;
4625 /* If we didn't create a PARM_DECL for the formal, this means that
4626 it is an Out parameter not passed by reference and that need not
4627 be copied in. In this case, the value of the actual need not be
4628 read. However, we still need to make sure that its side-effects
4629 are evaluated before the call, so we evaluate its address. */
4631 {
4633 {
4636 }
4638 }
4642 /* If this is 'Null_Parameter, pass a zero even though we are
4643 dereferencing it. */
4649 gnu_actual
4653 integer_zero_node),
4655 else
4657 }
4660 }
4662 gnu_call
4666 /* If we have created a temporary for the return value, initialize it. */
4668 {
4669 tree gnu_stmt
4674 }
4676 /* If this is a subprogram with copy-in/copy-out parameters, we need to
4677 unpack the valued returned from the function into the In Out or Out
4678 parameters. We deal with the function return (if this is an Ada
4679 function) below. */
4681 {
4682 /* List of FIELD_DECLs associated with the PARM_DECLs of the copy-in/
4683 copy-out parameters. */
4687 /* The call sequence must contain one and only one call, even though the
4688 function is pure. Save the result into a temporary if needed. */
4690 {
4692 {
4693 tree gnu_stmt;
4694 /* If we haven't pushed a binding level, push a new one. This
4695 will narrow the lifetime of the temporary we are about to
4696 make as much as possible. */
4698 {
4702 }
4703 gnu_call
4706 }
4709 }
4711 /* The first entry is for the actual return value if this is a
4712 function, so skip it. */
4718 else
4725 /* If we are dealing with a copy-in/copy-out parameter, we must
4726 retrieve its value from the record returned in the call. */
4732 {
4733 /* Get the value to assign to this Out or In Out parameter. It is
4734 either the result of the function if there is only a single such
4735 parameter or the appropriate field from the record returned. */
4736 tree gnu_result
4738 ? gnu_call
4742 /* If the actual is a conversion, get the inner expression, which
4743 will be the real destination, and convert the result to the
4744 type of the actual parameter. */
4745 tree gnu_actual
4748 /* If the result is a padded type, remove the padding. */
4750 gnu_result
4752 gnu_result);
4754 /* If the actual is a type conversion, the real target object is
4755 denoted by the inner Expression and we need to convert the
4756 result to the associated type.
4757 We also need to convert our gnu assignment target to this type
4758 if the corresponding GNU_NAME was constructed from the GNAT
4759 conversion node and not from the inner Expression. */
4761 {
4762 gnu_result
4763 = convert_with_check
4771 }
4773 /* Unchecked conversions as actuals for Out parameters are not
4774 allowed in user code because they are not variables, but do
4775 occur in front-end expansions. The associated GNU_NAME is
4776 always obtained from the inner expression in such cases. */
4779 gnu_result,
4781 else
4782 {
4784 gnu_result
4786 gnat_actual);
4791 }
4793 /* If an outer atomic access is required for an actual parameter,
4794 build the load-modify-store sequence. */
4796 gnu_result
4799 /* Or else, if simple atomic access is required, build the atomic
4800 store. */
4804 /* Otherwise build a regular assignment. */
4805 else
4814 }
4815 }
4817 /* If this is a function call, the result is the call expression unless a
4818 target is specified, in which case we copy the result into the target
4819 and return the assignment statement. */
4821 {
4822 /* If this is a function with copy-in/copy-out parameters, extract the
4823 return value from it and update the return type. */
4825 {
4827 gnu_call
4830 }
4832 /* If the function returns an unconstrained array or by direct reference,
4833 we have to dereference the pointer. */
4839 {
4843 /* If range check is needed, emit code to generate it. */
4845 gnu_call
4847 gnat_parent);
4849 /* ??? If the return type has variable size, then force the return
4850 slot optimization as we would not be able to create a temporary.
4851 That's what has been done historically. */
4854 else
4857 /* Use the required method to move the result to the target. */
4859 gnu_call
4863 else
4864 gnu_call
4870 }
4871 else
4873 }
4875 /* Otherwise, if this is a procedure call statement without copy-in/copy-out
4876 parameters, the result is just the call statement. */
4880 /* Finally, add the copy back statements, if any. */
4886 /* If we have pushed a binding level, pop it and finish up the enclosing
4887 statement group. */
4889 {
4893 }
4895 /* Otherwise, retrieve the statement list, if any. */
4899 /* Otherwise, just return the call expression. */
4900 else
4903 /* If we nevertheless need a value, make a COMPOUND_EXPR to return it.
4904 But first simplify if we have only one statement in the list. */
4906 {
4910 gnu_result
4912 }
4915 }
4916 \f
4917 /* Subroutine of gnat_to_gnu to translate gnat_node, an
4918 N_Handled_Sequence_Of_Statements, to a GCC tree, which is returned. */
4920 static tree
4922 {
4925 /* If just annotating, ignore all EH and cleanups. */
4929 bool setjmp_longjmp
4935 tree gnu_result;
4936 tree gnu_expr;
4937 Node_Id gnat_temp;
4938 /* Node providing the sloc for the cleanup actions. */
4941 gnat_node);
4943 /* The GCC exception handling mechanism can handle both ZCX and SJLJ schemes
4944 and we have our own SJLJ mechanism. To call the GCC mechanism, we call
4945 add_cleanup, and when we leave the binding, end_stmt_group will create
4946 the TRY_FINALLY_EXPR.
4948 ??? The region level calls down there have been specifically put in place
4949 for a ZCX context and currently the order in which things are emitted
4950 (region/handlers) is different from the SJLJ case. Instead of putting
4951 other calls with different conditions at other places for the SJLJ case,
4952 it seems cleaner to reorder things for the SJLJ case and generalize the
4953 condition to make it not ZCX specific.
4955 If there are any exceptions or cleanup processing involved, we need an
4956 outer statement group (for Setjmp_Longjmp) and binding level. */
4958 {
4961 }
4963 /* If using setjmp_longjmp, make the variables for the setjmp buffer and save
4964 area for address of previous buffer. Do this first since we need to have
4965 the setjmp buf known for any decls in this block. */
4967 {
4968 gnu_jmpsave_decl
4970 jmpbuf_ptr_type,
4975 /* The __builtin_setjmp receivers will immediately reinstall it. Now
4976 because of the unstructured form of EH used by setjmp_longjmp, there
4977 might be forward edges going to __builtin_setjmp receivers on which
4978 it is uninitialized, although they will never be actually taken. */
4980 gnu_jmpbuf_decl
4982 jmpbuf_type,
4983 NULL_TREE,
4989 /* When we exit this block, restore the saved value. */
4991 gnat_cleanup_loc_node);
4992 }
4994 /* If we are to call a function when exiting this block, add a cleanup
4995 to the binding level we made above. Note that add_cleanup is FIFO
4996 so we must register this cleanup after the EH cleanup just above. */
4998 {
5000 /* When not optimizing, disable inlining of finalizers as this can
5001 create a more complex CFG in the parent function. */
5005 }
5007 /* Now build the tree for the declarations and statements inside this block.
5008 If this is SJLJ, set our jmp_buf as the current buffer. */
5012 {
5015 gnu_jmpbuf_decl));
5018 }
5024 /* Generate code for each statement in the block. */
5032 /* Now generate code for the two exception models, if either is relevant for
5033 this block. */
5035 {
5037 tree gnu_handler;
5039 /* Make a binding level for the exception handling declarations and code
5040 and set up gnu_except_ptr_stack for the handlers to use. */
5051 /* Generate code for each handler. The N_Exception_Handler case does the
5052 real work and returns a COND_EXPR for each handler, which we chain
5053 together here. */
5056 {
5059 /* If this is the first one, set it as the outer one. Otherwise,
5060 point the "else" part of the previous handler to us. Then point
5061 to our "else" part. */
5064 else
5068 }
5070 /* If none of the exception handlers did anything, re-raise but do not
5071 defer abortion. */
5074 set_expr_location_from_node
5080 else
5083 /* End the binding level dedicated to the exception handlers and get the
5084 whole statement group. */
5089 /* If the setjmp returns 1, we restore our incoming longjmp value and
5090 then check the handlers. */
5093 gnu_jmpsave_decl),
5094 gnat_node);
5098 /* This block is now "if (setjmp) ... <handlers> else <block>". */
5100 (build_call_n_expr
5103 gnu_jmpbuf_decl))),
5105 }
5107 {
5108 tree gnu_handlers;
5109 location_t locus;
5111 /* First make a block containing the handlers. */
5119 /* Now make the TRY_CATCH_EXPR for the block. */
5122 /* Set a location. We need to find a unique location for the dispatching
5123 code, otherwise we can get coverage or debugging issues. Try with
5124 the location of the end label. */
5128 else
5129 /* Clear column information so that the exception handler of an
5130 implicit transient block does not incorrectly inherit the slocs
5131 of a decision, which would otherwise confuse control flow based
5132 coverage analysis tools. */
5134 }
5135 else
5138 /* Now close our outer block, if we had to make one. */
5140 {
5144 }
5147 }
5148 \f
5149 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5150 to a GCC tree, which is returned. This is the variant for Setjmp_Longjmp
5151 exception handling. */
5153 static tree
5155 {
5156 /* Unless this is "Others" or the special "Non-Ada" exception for Ada, make
5157 an "if" statement to select the proper exceptions. For "Others", exclude
5158 exceptions where Handled_By_Others is nonzero unless the All_Others flag
5159 is set. For "Non-ada", accept an exception if "Lang" is 'V'. */
5162 Node_Id gnat_temp;
5166 {
5167 tree this_choice;
5170 {
5173 else
5174 this_choice
5175 = build_binary_op
5177 convert
5179 build_component_ref
5180 (build_unary_op
5183 not_handled_by_others_decl,
5185 integer_zero_node);
5186 }
5190 {
5192 tree gnu_expr;
5194 /* Exception may be a renaming. Recover original exception which is
5195 the one elaborated and registered. */
5201 this_choice
5202 = build_binary_op
5207 }
5208 else
5213 }
5216 }
5217 \f
5218 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Exception_Handler,
5219 to a GCC tree, which is returned. This is the variant for ZCX. */
5221 static tree
5223 {
5226 Node_Id gnat_temp;
5228 /* We build a TREE_LIST of nodes representing what exception types this
5229 handler can catch, with special cases for others and all others cases.
5231 Each exception type is actually identified by a pointer to the exception
5232 id, or to a dummy object for "others" and "all others". */
5235 {
5239 {
5242 }
5245 {
5248 /* Exception may be a renaming. Recover original exception which is
5249 the one elaborated and registered. */
5255 }
5256 else
5259 /* The GCC interface expects NULL to be passed for catch all handlers, so
5260 it would be quite tempting to set gnu_etypes_list to NULL if gnu_etype
5261 is integer_zero_node. It would not work, however, because GCC's
5262 notion of "catch all" is stronger than our notion of "others". Until
5263 we correctly use the cleanup interface as well, doing that would
5264 prevent the "all others" handlers from being seen, because nothing
5265 can be caught beyond a catch all from GCC's point of view. */
5267 }
5272 /* Expand a call to the begin_handler hook at the beginning of the handler,
5273 and arrange for a call to the end_handler hook to occur on every possible
5274 exit path.
5276 The hooks expect a pointer to the low level occurrence. This is required
5277 for our stack management scheme because a raise inside the handler pushes
5278 a new occurrence on top of the stack, which means that this top does not
5279 necessarily match the occurrence this handler was dealing with.
5281 __builtin_eh_pointer references the exception occurrence being
5282 propagated. Upon handler entry, this is the exception for which the
5283 handler is triggered. This might not be the case upon handler exit,
5284 however, as we might have a new occurrence propagated by the handler's
5285 body, and the end_handler hook called as a cleanup in this context.
5287 We use a local variable to retrieve the incoming value at handler entry
5288 time, and reuse it to feed the end_handler hook's argument at exit. */
5290 gnu_current_exc_ptr
5294 gnu_incoming_exc_ptr
5301 gnu_incoming_exc_ptr),
5302 gnat_node);
5304 /* Declare and initialize the choice parameter, if present. */
5306 {
5307 tree gnu_param
5313 gnu_incoming_exc_ptr));
5314 }
5316 /* We don't have an End_Label at hand to set the location of the cleanup
5317 actions, so we use that of the exception handler itself instead. */
5319 gnat_node);
5325 return
5327 }
5328 \f
5329 /* Subroutine of gnat_to_gnu to generate code for an N_Compilation unit. */
5331 static void
5333 {
5338 Entity_Id gnat_entity;
5339 Node_Id gnat_pragma;
5340 /* Make the decl for the elaboration procedure. */
5341 tree gnu_elab_proc_decl
5342 = create_subprog_decl
5351 /* Initialize the information structure for the function. */
5360 /* For a body, first process the spec if there is one. */
5366 {
5373 }
5375 /* Then process any pragmas and declarations preceding the unit. */
5384 /* Process the unit itself. */
5387 /* Generate code for all the inlined subprograms. */
5391 {
5392 Node_Id gnat_body;
5394 /* Without optimization, process only the required subprograms. */
5400 {
5401 /* ??? This happens when only the spec of a package is provided. */
5405 gnat_body
5407 }
5409 /* Define the entity first so we set DECL_EXTERNAL. */
5412 }
5414 /* Process any pragmas and actions following the unit. */
5419 /* Save away what we've made so far and finish it up. */
5426 /* Record this potential elaboration procedure for later processing. */
5433 /* Force the processing for all nodes that remain in the queue. */
5435 }
5436 \f
5437 /* Mark COND, a boolean expression, as predicating a call to a noreturn
5438 function, i.e. predict that it is very likely false, and return it.
5440 The compiler will automatically predict the last edge leading to a call
5441 to a noreturn function as very unlikely taken. This function makes it
5442 possible to expand the prediction to predecessors in case the condition
5443 is made up of several short-circuit operators. */
5445 static tree
5447 {
5457 PRED_NORETURN));
5460 }
5462 /* Subroutine of gnat_to_gnu to translate gnat_node, an N_Raise_xxx_Error,
5463 to a GCC tree, which is returned. GNU_RESULT_TYPE_P is a pointer to where
5464 we should place the result type. LABEL_P is true if there is a label to
5465 branch to for the exception. */
5467 static tree
5469 {
5473 const bool with_extra_info
5474 = Exception_Extra_Info
5482 {
5492 {
5498 {
5518 }
5525 && gnu_low_bound
5526 && gnu_high_bound
5529 gnu_result
5533 /* If optimization is enabled and we are inside a loop, we try to
5534 compute invariant conditions for checks applied to the iteration
5535 variable, i.e. conditions that are independent of the variable
5536 and necessary in order for the checks to fail in the course of
5537 some iteration. If we succeed, we consider an alternative:
5539 1. If loop unswitching is enabled, we prepend these conditions
5540 to the original conditions of the checks. This will make it
5541 possible for the loop unswitching pass to replace the loop
5542 with two loops, one of which has the checks eliminated and
5543 the other has the original checks reinstated, and a prologue
5544 implementing a run-time selection. The former loop will be
5545 for example suitable for vectorization.
5547 2. Otherwise, we instead append the conditions to the original
5548 conditions of the checks. At worse, if the conditions cannot
5549 be evaluated at compile time, they will be evaluated as true
5550 at run time only when the checks have already failed, thus
5551 contributing negatively only to the size of the executable.
5552 But the hope is that these invariant conditions be evaluated
5553 at compile time to false, thus taking away the entire checks
5554 with them. */
5557 && (!gnu_low_bound
5559 && (!gnu_high_bound
5562 {
5567 rci->inserted_cond
5574 boolean_type_node,
5576 gnu_cond);
5577 else
5579 boolean_type_node,
5580 gnu_cond,
5582 }
5584 /* Or else, if aggressive loop optimizations are enabled, we just
5585 record that there are checks applied to iteration variables. */
5587 && flag_aggressive_loop_optimizations
5591 }
5596 }
5598 common:
5603 /* If the type is VOID, this is a statement, so we need to generate the code
5604 for the call. Handle a condition, if there is one. */
5606 {
5608 {
5613 }
5614 }
5615 else
5619 }
5620 \f
5621 /* Return true if GNAT_NODE is on the LHS of an assignment or an actual
5622 parameter of a call. */
5624 static bool
5626 {
5641 }
5643 /* Return true if either GNAT_NODE or a view of GNAT_NODE is on the LHS
5644 of an assignment or an actual parameter of a call. */
5646 static bool
5648 {
5649 Node_Kind kind;
5661 }
5663 /* Return true if GNAT_NODE, an unchecked type conversion, is a no-op as far
5664 as gigi is concerned. This is used to avoid conversions on the LHS. */
5666 static bool
5668 {
5671 /* The conversion must be on the LHS of an assignment or an actual parameter
5672 of a call. Otherwise, even if the conversion was essentially a no-op, it
5673 could de facto ensure type consistency and this should be preserved. */
5679 /* We're interested in artificial conversions generated by the front-end
5680 to make private types explicit, e.g. in Expand_Assign_Array. */
5687 /* The direct conversion to the underlying type is a no-op. */
5691 /* For an array subtype, the conversion to the PAIT is a no-op. */
5696 /* For a record subtype, the conversion to the type is a no-op. */
5702 }
5704 /* This function is the driver of the GNAT to GCC tree transformation process.
5705 It is the entry point of the tree transformer. GNAT_NODE is the root of
5706 some GNAT tree. Return the root of the corresponding GCC tree. If this
5707 is an expression, return the GCC equivalent of the expression. If this
5708 is a statement, return the statement or add it to the current statement
5709 group, in which case anything returned is to be interpreted as occurring
5710 after anything added. */
5712 tree
5714 {
5720 Node_Id gnat_temp;
5723 /* Save node number for error message and set location information. */
5727 /* If this node is a statement and we are only annotating types, return an
5728 empty statement list. */
5732 /* If this node is a non-static subexpression and we are only annotating
5733 types, make this into a NULL_EXPR. */
5740 N_Raise_Constraint_Error));
5749 {
5752 /* If this is a statement and we are at top level, it must be part of
5753 the elaboration procedure, so mark us as being in that procedure. */
5755 {
5758 }
5760 /* If we are in the elaboration procedure, check if we are violating a
5761 No_Elaboration_Code restriction by having a statement there. Don't
5762 check for a possible No_Elaboration_Code restriction violation on
5763 N_Handled_Sequence_Of_Statements, as we want to signal an error on
5764 every nested real statement instead. This also avoids triggering
5765 spurious errors on dummy (empty) sequences created by the front-end
5766 for package bodies in some cases. */
5770 }
5773 {
5774 /********************************/
5775 /* Chapter 2: Lexical Elements */
5776 /********************************/
5785 /* If atomic access is required on the RHS, build the atomic load. */
5792 {
5793 tree gnu_type;
5795 /* Get the type of the result, looking inside any padding and
5796 justified modular types. Then get the value in that type. */
5805 /* If the result overflows (meaning it doesn't fit in its base type),
5806 abort. We would like to check that the value is within the range
5807 of the subtype, but that causes problems with subtypes whose usage
5808 will raise Constraint_Error and with biased representation, so
5809 we don't. */
5811 }
5815 /* If a Entity is present, it means that this was one of the
5816 literals in a user-defined character type. In that case,
5817 just return the value in the CONST_DECL. Otherwise, use the
5818 character code. In that case, the base type should be an
5819 INTEGER_TYPE, but we won't bother checking for that. */
5823 else
5824 gnu_result
5825 = build_int_cst_type
5832 /* If this is of a fixed-point type, the value we want is the value of
5833 the corresponding integer. */
5835 {
5837 gnu_result_type);
5839 }
5841 else
5842 {
5845 /* First convert the value to a machine number if it isn't already.
5846 That will force the base to 2 for non-zero values and simplify
5847 the rest of the logic. */
5849 ur_realval
5855 else
5856 {
5857 REAL_VALUE_TYPE tmp;
5861 /* The base must be 2 as Machine guarantees this, so we scale
5862 the value, which we know can fit in the mantissa of the type
5863 (hence the use of that type above). */
5868 }
5870 /* Now see if we need to negate the result. Do it this way to
5871 properly handle -0. */
5873 gnu_result
5875 gnu_result);
5876 }
5883 {
5890 else
5893 /* Build the string with the characters in the literal. Note
5894 that Ada strings are 1-origin. */
5898 /* Put a null at the end of the string in case it's in a context
5899 where GCC will want to treat it as a C string. */
5904 /* Strings in GCC don't normally have types, but we want
5905 this to not be converted to the array type. */
5910 }
5911 else
5912 {
5913 /* Build a list consisting of each character, then make
5914 the aggregate. */
5924 {
5930 }
5933 }
5940 /**************************************/
5941 /* Chapter 3: Declarations and Types */
5942 /**************************************/
5959 /* If we are just annotating types and this object has an unconstrained
5960 or task type, don't elaborate it. */
5970 && (!type_annotate_only
5972 {
5975 gnu_expr
5980 }
5981 else
5984 /* If this is a deferred constant with an address clause, we ignore the
5985 full view since the clause is on the partial view and we cannot have
5986 2 different GCC trees for the object. The only bits of the full view
5987 we will use is the initializer, but it will be directly fetched. */
5993 /* If this object has its elaboration delayed, we must force evaluation
5994 of GNU_EXPR now and save it for the freeze point. Note that we need
5995 not do anything special at the global level since the lifetime of the
5996 temporary is fully contained within the elaboration routine. */
5998 {
6000 {
6003 }
6004 }
6005 else
6013 /* Don't do anything if this renaming is handled by the front end or if
6014 we are just annotating types and this object has a composite or task
6015 type, don't elaborate it. */
6017 && ! (type_annotate_only
6021 {
6022 tree gnu_temp
6025 /* See case 2 of renaming in gnat_to_gnu_entity. */
6028 }
6035 /* See the above case for the rationale. */
6037 {
6038 tree gnu_temp
6043 }
6047 {
6053 /* Materializing renamed subprograms will only benefit the debugging
6054 information as they aren't referenced in the generated code. So
6055 skip them when they aren't needed. Avoid doing this if:
6057 - there is a freeze node: in this case the renamed entity is not
6058 elaborated yet,
6059 - the renamed subprogram is intrinsic: it will not be available in
6060 the debugging information (note that both or only one of the
6061 renaming and the renamed subprograms can be intrinsic). */
6072 }
6081 /* These are fully handled in the front end. */
6082 /* ??? For package renamings, find a way to use GENERIC namespaces so
6083 that we get proper debug information for them. */
6087 /*************************************/
6088 /* Chapter 4: Names and Expressions */
6089 /*************************************/
6096 /* If atomic access is required on the RHS, build the atomic load. */
6103 {
6105 tree gnu_type;
6112 /* Convert vector inputs to their representative array type, to fit
6113 what the code below expects. */
6115 {
6119 }
6123 /* If we got a padded type, remove it too. */
6125 gnu_array_object
6127 gnu_array_object);
6131 /* The failure of this assertion will very likely come from a missing
6132 expansion for a packed array access. */
6135 /* First compute the number of dimensions of the array, then
6136 fill the expression array, the order depending on whether
6137 this is a Convention_Fortran array or not. */
6142 ;
6151 else
6160 {
6167 gnu_expr
6168 = emit_index_check
6172 gnat_temp);
6174 gnu_result
6177 /* Array accesses are bound-checked so they cannot trap, but this
6178 is valid only if they are not hoisted ahead of the check. We
6179 need to mark them as no-trap to get decent loop optimizations
6180 in the presence of -fnon-call-exceptions, so we do it when we
6181 know that the original expression had no side-effects. */
6187 /* If aggressive loop optimizations are enabled, we warn for loops
6188 overrunning a simple array of size 1 not at the end of a record.
6189 This is aimed to catch misuses of the trailing array idiom. */
6191 && flag_aggressive_loop_optimizations
6207 {
6210 }
6211 }
6215 /* If atomic access is required on the RHS, build the atomic load. */
6219 }
6223 {
6225 tree gnu_type;
6230 /* Do any implicit dereferences of the prefix and do any needed
6231 range check. */
6236 {
6237 /* Get the bounds of the slice. */
6238 tree gnu_index_type
6242 /* Get the permitted bounds. */
6243 tree gnu_base_index_type
6245 tree gnu_base_min_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
6247 tree gnu_base_max_expr = SUBSTITUTE_PLACEHOLDER_IN_EXPR
6254 /* Derive a good type to convert everything to. */
6257 /* Test whether the minimum slice value is too small. */
6260 gnu_min_expr),
6262 gnu_base_min_expr));
6264 /* Test whether the maximum slice value is too large. */
6267 gnu_max_expr),
6269 gnu_base_max_expr));
6271 /* Build a slice index check that returns the low bound,
6272 assuming the slice is not empty. */
6273 gnu_expr = emit_check
6278 /* Build a conditional expression that does the index checks and
6279 returns the low bound if the slice is not empty (max >= min),
6280 and returns the naked low bound otherwise (max < min), unless
6281 it is non-constant and the high bound is; this prevents VRP
6282 from inferring bogus ranges on the unlikely path. */
6286 gnu_max_expr),
6288 gnu_min_expr)),
6289 gnu_expr,
6293 }
6294 else
6295 /* Simply return the naked low bound. */
6298 /* If this is a slice with non-constant size of an array with constant
6299 size, set the maximum size for the allocation of temporaries. */
6306 }
6310 {
6314 tree gnu_field;
6318 /* For discriminant references in tagged types always substitute the
6319 corresponding discriminant as the actual selected component. */
6324 /* For discriminant references of untagged types always substitute the
6325 corresponding stored discriminant. */
6329 /* Handle extracting the real or imaginary part of a complex.
6330 The real part is the first field and the imaginary the last. */
6335 else
6336 {
6339 gnu_result
6343 && lvalue_required_for_attribute_p
6345 }
6349 /* If atomic access is required on the RHS, build the atomic load. */
6353 }
6357 {
6358 /* The attribute designator. */
6361 /* The Elab_Spec and Elab_Body attributes are special in that Prefix
6362 is a unit, not an object with a GCC equivalent. */
6364 return
6372 }
6376 /* Like 'Access as far as we are concerned. */
6384 {
6385 tree gnu_aggr_type;
6387 /* ??? It is wrong to evaluate the type now, but there doesn't
6388 seem to be any other practical way of doing it. */
6392 gnu_aggr_type = gnu_result_type
6397 gnu_aggr_type
6404 NULL);
6408 gnu_result
6411 gnu_aggr_type);
6414 gnu_aggr_type,
6417 gnu_result
6418 = build_binary_op
6423 (Next
6425 else
6429 }
6437 else
6444 /* Get the operand expression. */
6448 /* If this is a qualified expression for a tagged type, we mark the type
6449 as used. Because of polymorphism, this might be the only reference to
6450 the tagged type in the program while objects have it as dynamic type.
6451 The debugger needs to see it to display these objects properly. */
6455 gnu_result
6459 kind == N_Type_Conversion
6466 /* Skip further processing if the conversion is deemed a no-op. */
6468 {
6471 }
6475 /* If the result is a pointer type, see if we are improperly
6476 converting to a stricter alignment. */
6479 {
6485 post_error_ne_tree_2
6489 }
6491 /* If we are converting a descriptor to a function pointer, first
6492 build the pointer. */
6504 {
6509 /* GNAT_RANGE is either an N_Range node or an identifier denoting a
6510 subtype. */
6512 {
6515 }
6518 {
6522 gnu_low
6524 gnu_high
6526 }
6527 else
6532 /* If LOW and HIGH are identical, perform an equality test. Otherwise,
6533 ensure that GNU_OBJ is evaluated only once and perform a full range
6534 test. */
6536 gnu_result
6538 else
6539 {
6548 gnu_result
6550 }
6553 gnu_result
6555 }
6563 ? RDIV_EXPR
6570 /* These can either be operations on booleans or on modular types.
6571 Fall through for boolean types since that's the way GNU_CODES is
6572 set up. */
6574 {
6575 enum tree_code code
6586 }
6588 /* ... fall through ... */
6600 {
6604 tree gnu_type;
6610 /* Pending generic support for efficient vector logical operations in
6611 GCC, convert vectors to their representative array type view and
6612 fallthrough. */
6616 /* If this is a comparison operator, convert any references to an
6617 unconstrained array value into a reference to the actual array. */
6619 {
6622 }
6624 /* If this is a shift whose count is not guaranteed to be correct,
6625 we need to adjust the shift count. */
6627 {
6629 tree gnu_max_shift
6636 gnu_rhs
6637 = build_binary_op
6640 gnu_count_type,
6641 gnu_max_shift,
6643 integer_one_node)),
6644 gnu_rhs);
6645 }
6647 /* For right shifts, the type says what kind of shift to do,
6648 so we may need to choose a different type. In this case,
6649 we have to ignore integer overflow lest it propagates all
6650 the way down and causes a CE to be explicitly raised. */
6652 {
6655 }
6658 {
6661 }
6664 {
6670 }
6672 /* Instead of expanding overflow checks for addition, subtraction
6673 and multiplication itself, the front end will leave this to
6674 the back end when Backend_Overflow_Checks_On_Target is set.
6675 As the GCC back end itself does not know yet how to properly
6676 do overflow checking, do it here. The goal is to push
6677 the expansions further into the back end over time. */
6686 else
6687 {
6688 /* Some operations, e.g. comparisons of arrays, generate complex
6689 trees that need to be annotated while they are being built. */
6692 }
6694 /* If this is a logical shift with the shift count not verified,
6695 we must return zero if it is too large. We cannot compensate
6696 above in this case. */
6699 gnu_result
6700 = build_cond_expr
6703 gnu_rhs,
6707 gnu_result);
6708 }
6712 {
6715 tree gnu_false
6719 gnu_result
6721 }
6730 /* This case can apply to a boolean or a modular type.
6731 Fall through for a boolean operand since GNU_CODES is set
6732 up to handle this. */
6734 {
6738 gnu_expr);
6740 }
6742 /* ... fall through ... */
6751 gnu_result
6754 else
6760 {
6762 tree gnu_type;
6767 /* The Expression operand can either be an N_Identifier or
6768 Expanded_Name, which must represent a type, or a
6769 N_Qualified_Expression, which contains both the object type and an
6770 initial value for the object. */
6775 {
6776 Entity_Id gnat_desig_type
6784 gnu_init
6790 else
6791 {
6795 }
6797 /* See the N_Qualified_Expression case for the rationale. */
6802 }
6803 else
6810 ignore_init_type);
6811 }
6814 /**************************/
6815 /* Chapter 5: Statements */
6816 /**************************/
6824 /* When not optimizing, turn null statements from source into gotos to
6825 the next statement that the middle-end knows how to preserve. */
6827 {
6838 }
6839 else
6844 /* Get the LHS and RHS of the statement and convert any reference to an
6845 unconstrained array into a reference to the underlying array. */
6848 /* If the type has a size that overflows, convert this into raise of
6849 Storage_Error: execution shouldn't have gotten here anyway. */
6853 N_Raise_Storage_Error);
6855 {
6856 bool outer_atomic_access
6858 bool atomic_access
6859 = !outer_atomic_access
6861 gnu_result
6864 }
6865 else
6866 {
6868 const Entity_Id gnat_type
6870 const bool regular_array_type_p
6872 const bool use_memset_p
6873 = (regular_array_type_p
6877 /* If we'll use memset, we need to find the inner expression. */
6879 {
6880 Node_Id gnat_inner
6884 gnat_inner
6887 }
6888 else
6891 /* If range check is needed, emit code to generate it. */
6894 gnat_node);
6896 /* If an outer atomic access is required on the LHS, build the load-
6897 modify-store sequence. */
6901 /* Or else, if atomic access is required, build the atomic store. */
6905 /* Or else, use memset when the conditions are met. */
6907 {
6911 tree size
6916 {
6917 tree mask
6921 }
6923 }
6925 /* Otherwise build a regular assignment. */
6926 else
6927 gnu_result
6930 /* If the assignment type is a regular array and the two sides are
6931 not completely disjoint, play safe and use memmove. But don't do
6932 it for a bit-packed array as it might not be byte-aligned. */
6934 && regular_array_type_p
6936 {
6940 tree size
6946 }
6947 }
6951 {
6954 /* Make the outer COND_EXPR. Avoid non-determinism. */
6963 /* Now make a COND_EXPR for each of the "else if" parts. Put each
6964 into the previous "else" part and point to where to put any
6965 outer "else". Also avoid non-determinism. */
6969 {
6979 }
6982 }
6994 /* The only way to enter the block is to fall through to it. */
6996 {
7003 }
7004 else
7009 gnu_result
7019 {
7022 /* If the subprogram is a function, we must return the expression. */
7024 {
7027 /* If this function has copy-in/copy-out parameters parameters and
7028 doesn't return by invisible reference, get the real object for
7029 the return. See Subprogram_Body_to_gnu. */
7033 else
7036 /* Get the GCC tree for the expression to be returned. */
7039 /* Do not remove the padding from GNU_RET_VAL if the inner type is
7040 self-referential since we want to allocate the fixed size. */
7042 && type_is_padding_self_referential
7046 /* If the function returns by direct reference, return a pointer
7047 to the return value. */
7052 /* Otherwise, if it returns an unconstrained array, we have to
7053 allocate a new version of the result and return it. */
7055 {
7058 /* And find out whether this is a candidate for Named Return
7059 Value. If so, record it. */
7061 {
7064 /* Strip useless conversions around the return value. */
7068 /* Strip unpadding around the return value. */
7070 && TYPE_IS_PADDING_P
7074 /* Now apply the test to the return value. */
7076 {
7082 }
7083 }
7086 gnu_ret_val,
7091 }
7093 /* Otherwise, if it returns by invisible reference, dereference
7094 the pointer it is passed using the type of the return value
7095 and build the copy operation manually. This ensures that we
7096 don't copy too much data, for example if the return type is
7097 unconstrained with a maximum size. */
7099 {
7100 tree gnu_ret_deref
7102 gnu_ret_obj);
7107 }
7108 }
7110 else
7113 /* If we have a return label defined, convert this into a branch to
7114 that label. The return proper will be handled elsewhere. */
7116 {
7119 gnu_ret_val));
7124 /* When not optimizing, make sure the return is preserved. */
7127 }
7129 /* Otherwise, build a regular return. */
7130 else
7132 }
7136 gnu_result
7140 /***************************/
7141 /* Chapter 6: Subprograms */
7142 /***************************/
7145 /* Unless there is a freeze node, declare the subprogram. We consider
7146 this a "definition" even though we're not generating code for
7147 the subprogram because we will be making the corresponding GCC
7148 node here. */
7157 /* This subprogram doesn't exist for code generation purposes, but we
7158 have to elaborate the types of any parameters and result, unless
7159 they are imported types (nothing to generate in this case).
7161 The parameter list may contain types with freeze nodes, e.g. not null
7162 subtypes, so the subprogram itself may carry a freeze node, in which
7163 case its elaboration must be deferred. */
7165 /* Process the parameter types first. */
7168 = First_Formal_With_Extras
7176 /* Then the result type, set to Standard_Void_Type for procedures. */
7177 {
7178 Entity_Id gnat_temp_type
7183 }
7189 /* For a child unit identifier go up a level to get the specification.
7190 We get this when we try to find the spec of a child unit package
7191 that is the compilation unit being compiled. */
7206 /************************/
7207 /* Chapter 7: Packages */
7208 /************************/
7224 /* If this is the body of a generic package - do nothing. */
7226 {
7229 }
7240 /********************************/
7241 /* Chapter 8: Visibility Rules */
7242 /********************************/
7246 /* Nothing to do here - but these may appear in list of declarations. */
7250 /*********************/
7251 /* Chapter 9: Tasks */
7252 /*********************/
7263 /*********************************************************/
7264 /* Chapter 10: Program Structure and Compilation Issues */
7265 /*********************************************************/
7268 /* This is not called for the main unit on which gigi is invoked. */
7277 /* Simply process whatever unit is being inserted. */
7280 else
7281 {
7284 }
7291 /***************************/
7292 /* Chapter 11: Exceptions */
7293 /***************************/
7296 /* If there is an At_End procedure attached to this node, and the EH
7297 mechanism is SJLJ, we must have at least a corresponding At_End
7298 handler, unless the No_Exception_Handlers restriction is set. */
7313 else
7318 /* Only for reraise in back-end exceptions mode. */
7325 /* Clear the current exception pointer so that the occurrence won't be
7326 deallocated. */
7366 /******************************/
7367 /* Chapter 12: Generic Units */
7368 /******************************/
7378 /* These nodes can appear on a declaration list but there is nothing to
7379 to be done with them. */
7383 /**************************************************/
7384 /* Chapter 13: Representation Clauses and */
7385 /* Implementation-Dependent Features */
7386 /**************************************************/
7391 /* The only one we need to deal with is 'Address since, for the others,
7392 the front-end puts the information elsewhere. */
7396 /* And we only deal with 'Address if the object has a Freeze node. */
7401 /* Get the value to use as the address and save it as the equivalent
7402 for the object. When it is frozen, gnat_to_gnu_entity will do the
7403 right thing. */
7410 /* We do nothing with these. SEM puts the information elsewhere. */
7416 {
7426 /* First retrieve the 3 operand lists built by the front-end. */
7429 {
7436 }
7440 {
7447 }
7451 gnu_clobbers
7454 gnu_clobbers);
7456 /* Then perform some standard checking and processing on the
7457 operands. In particular, mark them addressable if needed. */
7465 {
7467 constraint
7473 {
7474 /* If the operand is going to end up in memory,
7475 mark it addressable. Note that we don't test
7476 allows_mem like in the input case below; this
7477 is modelled on the C front-end. */
7479 {
7486 }
7487 }
7488 else
7492 }
7495 {
7497 constraint
7503 {
7504 /* If the operand is going to end up in memory,
7505 mark it addressable. */
7507 {
7514 }
7515 }
7516 else
7520 }
7526 }
7527 else
7532 /****************/
7533 /* Added Nodes */
7534 /****************/
7537 /* This construct doesn't define a scope so we don't push a binding
7538 level around the statement list, but we wrap it in a SAVE_EXPR to
7539 protect it from unsharing. Elaborate the expression as part of the
7540 same statement group as the actions so that the type declaration
7541 gets inserted there as well. This ensures that the type elaboration
7542 code is issued past the actions computing values on which it might
7543 depend. */
7552 gnu_result
7577 {
7582 /* If this is a thin pointer, we must first dereference it to create
7583 a fat pointer, then go back below to a thin pointer. The reason
7584 for this is that we need to have a fat pointer someplace in order
7585 to properly compute the size. */
7589 gnu_ptr));
7591 /* If this is a fat pointer, the object must have been allocated with
7592 the template in front of the array. So pass the template address,
7593 and get the total size; do it by converting to a thin pointer. */
7595 gnu_ptr
7597 (TYPE_OBJECT_RECORD_TYPE
7599 gnu_ptr);
7603 /* If this is a thin pointer, the object must have been allocated with
7604 the template in front of the array. So pass the template address,
7605 and get the total size. */
7607 gnu_ptr
7609 gnu_ptr,
7611 byte_position
7612 (DECL_CHAIN
7615 /* If we have a special dynamic constrained subtype on the node, use
7616 it to compute the size; otherwise, use the designated subtype. */
7618 {
7619 gnu_actual_obj_type
7623 gnu_actual_obj_type
7625 gnu_actual_obj_type,
7628 }
7629 else
7632 gnu_result
7635 gnu_obj_type,
7638 gnat_node);
7639 }
7647 else
7652 /* The only validation we currently do on an unchecked conversion is
7653 that of aliasing assumptions. */
7665 /* These nodes should only be present when annotating types. */
7671 /* Other nodes are not supposed to reach here. */
7673 }
7675 /* If we pushed the processing of the elaboration routine, pop it back. */
7679 /* When not optimizing, turn boolean rvalues B into B != false tests
7680 so that the code just below can put the location information of the
7681 reference to B on the inequality operator for better debug info. */
7695 boolean_false_node));
7697 /* Set the location information on the result. Note that we may have
7698 no result if we tried to build a CALL_EXPR node to a procedure with
7699 no side-effects and optimization is enabled. */
7703 /* If we're supposed to return something of void_type, it means we have
7704 something we're elaborating for effect, so just return. */
7708 /* If the result is a constant that overflowed, raise Constraint_Error. */
7710 {
7712 gnu_result
7715 N_Raise_Constraint_Error));
7716 }
7718 /* If the result has side-effects and is of an unconstrained type, make a
7719 SAVE_EXPR so that we can be sure it will only be referenced once. But
7720 this is useless for a call to a function that returns an unconstrained
7721 type with default discriminant, as we cannot compute the size of the
7722 actual returned object. We must do this before any conversions. */
7730 /* Now convert the result to the result type, unless we are in one of the
7731 following cases:
7733 1. If this is the LHS of an assignment or an actual parameter of a
7734 call, return the result almost unmodified since the RHS will have
7735 to be converted to our type in that case, unless the result type
7736 has a simpler size. Likewise if there is just a no-op unchecked
7737 conversion in-between. Similarly, don't convert integral types
7738 that are the operands of an unchecked conversion since we need
7739 to ignore those conversions (for 'Valid).
7741 2. If we have a label (which doesn't have any well-defined type), a
7742 field or an error, return the result almost unmodified. Similarly,
7743 if the two types are record types with the same name, don't convert.
7744 This will be the case when we are converting from a packable version
7745 of a type to its original type and we need those conversions to be
7746 NOPs in order for assignments into these types to work properly.
7748 3. If the type is void or if we have no result, return error_mark_node
7749 to show we have no result.
7751 4. If this is a call to a function that returns with variable size and
7752 the call is used as the expression in either an object or a renaming
7753 declaration, return the result unmodified because we want to use the
7754 return slot optimization in this case.
7756 5. Finally, if the type of the result is already correct. */
7774 && (CONTAINS_PLACEHOLDER_P
7778 {
7779 /* Remove padding only if the inner object is of self-referential
7780 size: in that case it must be an object of unconstrained type
7781 with a default discriminant and we want to avoid copying too
7782 much data. */
7785 gnu_result);
7786 }
7795 {
7796 /* Remove any padding. */
7799 gnu_result);
7800 }
7810 ;
7815 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on the result. */
7822 }
7823 \f
7824 /* Subroutine of above to push the exception label stack. GNU_STACK is
7825 a pointer to the stack to update and GNAT_LABEL, if present, is the
7826 label to push onto the stack. */
7828 static void
7830 {
7836 }
7837 \f
7838 /* Record the current code position in GNAT_NODE. */
7840 static void
7842 {
7847 }
7849 /* Insert the code for GNAT_NODE at the position saved for that node. */
7851 static void
7853 {
7856 }
7857 \f
7858 /* Start a new statement group chained to the previous group. */
7860 void
7862 {
7865 /* First see if we can get one from the free list. */
7868 else
7874 }
7876 /* Add GNU_STMT to the current statement group. If it is an expression with
7877 no effects, it is ignored. */
7879 void
7881 {
7883 }
7885 /* Similar, but the statement is always added, regardless of side-effects. */
7887 void
7889 {
7891 }
7893 /* Like add_stmt, but set the location of GNU_STMT to that of GNAT_NODE. */
7895 void
7897 {
7898 /* Do not emit a location for renamings that come from generic instantiation,
7899 they are likely to disturb debugging. */
7904 }
7906 /* Similar, but the statement is always added, regardless of side-effects. */
7908 void
7910 {
7914 }
7916 /* Add a declaration statement for GNU_DECL to the current statement group.
7917 Get SLOC from Entity_Id. */
7919 void
7921 {
7925 /* If this is a variable that Gigi is to ignore, we may have been given
7926 an ERROR_MARK. So test for it. We also might have been given a
7927 reference for a renaming. So only do something for a decl. Also
7928 ignore a TYPE_DECL for an UNCONSTRAINED_ARRAY_TYPE. */
7936 /* If we are external or global, we don't want to output the DECL_EXPR for
7937 this DECL node since we already have evaluated the expressions in the
7938 sizes and positions as globals and doing it again would be wrong. */
7940 {
7941 /* Mark everything as used to prevent node sharing with subprograms.
7942 Note that walk_tree knows how to deal with TYPE_DECL, but neither
7943 VAR_DECL nor CONST_DECL. This appears to be somewhat arbitrary. */
7947 {
7951 }
7952 /* In any case, we have to deal with our own TYPE_ADA_SIZE field. */
7957 }
7958 else
7961 /* If this is a variable and an initializer is attached to it, it must be
7962 valid for the context. Similar to init_const in create_var_decl. */
7969 {
7970 /* If GNU_DECL has a padded type, convert it to the unpadded
7971 type so the assignment is done properly. */
7974 else
7981 {
7984 }
7987 }
7988 }
7990 /* Callback for walk_tree to mark the visited trees rooted at *TP. */
7992 static tree
7994 {
8000 /* Don't mark a dummy type as visited because we want to mark its sizes
8001 and fields once it's filled in. */
8009 }
8011 /* Mark nodes rooted at T with TREE_VISITED and types as having their
8012 sized gimplified. We use this to indicate all variable sizes and
8013 positions in global types may not be shared by any subprogram. */
8015 void
8017 {
8019 }
8021 /* Add GNU_CLEANUP, a cleanup action, to the current code group and
8022 set its location to that of GNAT_NODE if present, but with column info
8023 cleared so that conditional branches generated as part of the cleanup
8024 code do not interfere with coverage analysis tools. */
8026 static void
8028 {
8032 }
8034 /* Set the BLOCK node corresponding to the current code group to GNU_BLOCK. */
8036 void
8038 {
8041 }
8043 /* Return code corresponding to the current code group. It is normally
8044 a STATEMENT_LIST, but may also be a BIND_EXPR or TRY_FINALLY_EXPR if
8045 BLOCK or cleanups were set. */
8047 tree
8049 {
8053 /* If this is a null list, allocate a new STATEMENT_LIST. Then, if there
8054 are cleanups, make a TRY_FINALLY_EXPR. Last, if there is a BLOCK,
8055 make a BIND_EXPR. Note that we nest in that because the cleanup may
8056 reference variables in the block. */
8068 /* Remove this group from the stack and add it to the free list. */
8074 }
8076 /* Return whether the current statement group may fall through. */
8080 {
8083 else
8085 }
8087 /* Add a list of statements from GNAT_LIST, a possibly-empty list of
8088 statements.*/
8090 static void
8092 {
8093 Node_Id gnat_node;
8099 }
8101 /* Build a tree from GNAT_LIST, a possibly-empty list of statements.
8102 If BINDING_P is true, push and pop a binding level around the list. */
8104 static tree
8106 {
8118 }
8119 \f
8120 /* Generate GIMPLE in place for the expression at *EXPR_P. */
8122 int
8125 {
8128 tree op;
8134 {
8136 /* If this is an aggregate type, build a null pointer of the appropriate
8137 type and dereference it. */
8142 integer_zero_node));
8143 /* Otherwise, just make a VAR_DECL. */
8144 else
8145 {
8148 }
8154 /* We should only do this if we are just elaborating for side-effects,
8155 but we can't know that yet. */
8162 /* If we are taking the address of a constant CONSTRUCTOR, make sure it
8163 is put into static memory. We know that it's going to be read-only
8164 given the semantics we have and it must be in static memory when the
8165 reference is in an elaboration procedure. */
8167 {
8171 }
8173 /* Replace atomic loads with their first argument. That's necessary
8174 because the gimplifier would create a temporary otherwise. */
8177 {
8180 {
8186 else
8188 }
8189 else
8191 }
8198 /* If we are view-converting a CONSTRUCTOR or a call from an aggregate
8199 type to a scalar one, explicitly create the local temporary. That's
8200 required if the type is passed by reference. */
8204 {
8213 }
8220 /* The expressions for the RM bounds must be gimplified to ensure that
8221 they are properly elaborated. See gimplify_decl_expr. */
8225 {
8230 {
8235 {
8239 }
8243 {
8247 }
8249 }
8254 }
8256 /* ... fall through ... */
8260 }
8261 }
8263 /* Generate GIMPLE in place for the statement at *STMT_P. */
8265 static enum gimplify_status
8267 {
8271 {
8277 {
8283 /* Build the condition expression from the test, if any. */
8285 {
8286 /* Deal with the optimization hints. */
8290 annot_expr_ivdep_kind));
8294 annot_expr_no_vector_kind));
8298 annot_expr_vector_kind));
8300 gnu_cond
8303 }
8305 /* Set to emit the statements of the loop. */
8308 /* We first emit the start label and then a conditional jump to the
8309 end label if there's a top condition, then the update if it's at
8310 the top, then the body of the loop, then a conditional jump to
8311 the end label if there's a bottom condition, then the update if
8312 it's at the bottom, and finally a jump to the start label and the
8313 definition of the end label. */
8315 gnu_start_label),
8316 stmt_p);
8337 gnu_end_label),
8338 stmt_p);
8340 }
8343 /* Build a statement to jump to the corresponding end label, then
8344 see if it needs to be conditional. */
8353 }
8354 }
8355 \f
8356 /* Force a reference to each of the entities in GNAT_PACKAGE recursively.
8358 This routine is exclusively called in type_annotate mode, to compute DDA
8359 information for types in withed units, for ASIS use. */
8361 static void
8363 {
8364 Entity_Id gnat_entity;
8369 {
8372 /* We are interested only in entities visible from the main unit. */
8376 /* Skip stuff internal to the compiler. */
8384 /* Skip named numbers. */
8388 /* Skip generic declarations. */
8392 /* Skip package bodies. */
8396 /* Skip limited views that point back to the main unit. */
8402 /* Skip types that aren't frozen. */
8406 /* Recurse on real packages that aren't in the main unit. */
8408 {
8412 }
8413 else
8415 }
8416 }
8418 /* Force a reference to each of the entities in packages withed by GNAT_NODE.
8419 Operate recursively but check that we aren't elaborating something more
8420 than once.
8422 This routine is exclusively called in type_annotate mode, to compute DDA
8423 information for types in withed units, for ASIS use. */
8425 static void
8427 {
8428 Entity_Id gnat_with_clause;
8430 /* Process each unit only once. As we trace the context of all relevant
8431 units transitively, including generic bodies, we may encounter the
8432 same generic unit repeatedly. */
8436 /* Save entities in all context units. A body may have an implicit_with
8437 on its own spec, if the context includes a child unit, so don't save
8438 the spec twice. */
8445 {
8455 {
8458 /* Retrieve compilation unit node of generic body. */
8463 /* If body is available, elaborate its context. */
8466 }
8467 }
8471 }
8472 \f
8473 /* Do the processing of GNAT_NODE, an N_Freeze_Entity. */
8475 static void
8477 {
8482 /* If this is a package, we need to generate code for the package. */
8484 {
8485 insert_code_for
8489 }
8491 /* Don't do anything for class-wide types as they are always transformed
8492 into their root type. */
8496 /* Check for an old definition. This freeze node might be for an Itype. */
8497 gnu_old
8500 /* If this entity has an address representation clause, GNU_OLD is the
8501 address, so discard it here. */
8505 /* Don't do anything for subprograms that may have been elaborated before
8506 their freeze nodes. This can happen, for example, because of an inner
8507 call in an instance body or because of previous compilation of a spec
8508 for inlining purposes. */
8516 /* If we have a non-dummy type old tree, we have nothing to do, except
8517 aborting if this is the public view of a private type whose full view was
8518 not delayed, as this node was never delayed as it should have been. We
8519 let this happen for concurrent types and their Corresponding_Record_Type,
8520 however, because each might legitimately be elaborated before its own
8521 freeze node, e.g. while processing the other. */
8525 {
8533 }
8535 /* Reset the saved tree, if any, and elaborate the object or type for real.
8536 If there is a full view, elaborate it and use the result. And, if this
8537 is the root type of a class-wide type, reuse it for the latter. */
8539 {
8544 {
8551 {
8554 }
8555 }
8561 }
8565 {
8574 /* Propagate back-annotations from full view to partial view. */
8584 /* The above call may have defined this entity (the simplest example
8585 of this is when we have a private enumeral type since the bounds
8586 will have the public view). */
8589 }
8590 else
8591 {
8592 tree gnu_init
8598 }
8605 /* If we have an old type and we've made pointers to this type, update those
8606 pointers. If this is a Taft amendment type in the main unit, we need to
8607 mark the type as used since other units referencing it don't see the full
8608 declaration and, therefore, cannot mark it as used themselves. */
8610 {
8615 }
8616 }
8617 \f
8618 /* Elaborate decls in the lists GNAT_DECLS and GNAT_DECLS2, if present.
8619 We make two passes, one to elaborate anything other than bodies (but
8620 we declare a function if there was no spec). The second pass
8621 elaborates the bodies.
8623 GNAT_END_LIST gives the element in the list past the end. Normally,
8624 this is Empty, but can be First_Real_Statement for a
8625 Handled_Sequence_Of_Statements.
8627 We make a complete pass through both lists if PASS1P is true, then make
8628 the second pass over both lists if PASS2P is true. The lists usually
8629 correspond to the public and private parts of a package. */
8631 static void
8634 {
8636 Node_Id gnat_decl;
8646 {
8647 /* For package specs, we recurse inside the declarations,
8648 thus taking the two pass approach inside the boundary. */
8656 /* Similarly for any declarations in the actions of a
8657 freeze node. */
8659 {
8662 }
8664 /* Package bodies with freeze nodes get their elaboration deferred
8665 until the freeze node, but the code must be placed in the right
8666 place, so record the code position now. */
8674 (Corresponding_Spec
8677 record_code_position
8680 /* We defer most subprogram bodies to the second pass. */
8682 {
8684 {
8690 }
8691 }
8693 /* For bodies and stubs that act as their own specs, the entity
8694 itself must be elaborated in the first pass, because it may
8695 be used in other declarations. */
8697 {
8698 Node_Id gnat_subprog_id
8705 }
8707 /* Concurrent stubs stand for the corresponding subprogram bodies,
8708 which are deferred like other bodies. */
8711 ;
8713 /* Renamed subprograms may not be elaborated yet at this point
8714 since renamings do not trigger freezing. Wait for the second
8715 pass to take care of them. */
8717 ;
8719 else
8721 }
8723 /* Here we elaborate everything we deferred above except for package bodies,
8724 which are elaborated at their freeze nodes. Note that we must also
8725 go inside things (package specs and freeze nodes) the first pass did. */
8731 {
8750 }
8751 }
8752 \f
8753 /* Make a unary operation of kind CODE using build_unary_op, but guard
8754 the operation by an overflow check. CODE can be one of NEGATE_EXPR
8755 or ABS_EXPR. GNU_TYPE is the type desired for the result. Usually
8756 the operation is to be performed in that type. GNAT_NODE is the gnat
8757 node conveying the source location for which the error should be
8758 signaled. */
8760 static tree
8762 Node_Id gnat_node)
8763 {
8772 }
8774 /* Make a binary operation of kind CODE using build_binary_op, but guard
8775 the operation by an overflow check. CODE can be one of PLUS_EXPR,
8776 MINUS_EXPR or MULT_EXPR. GNU_TYPE is the type desired for the result.
8777 Usually the operation is to be performed in that type. GNAT_NODE is
8778 the GNAT node conveying the source location for which the error should
8779 be signaled. */
8781 static tree
8784 {
8794 /* Assert that the precision is a power of 2. */
8797 /* Prefer a constant or known-positive rhs to simplify checks. */
8803 {
8807 }
8811 /* If we can fold the expression to a constant, just return it.
8812 The caller will deal with overflow, no need to generate a check. */
8817 ? boolean_false_node
8820 /* ??? Should use more efficient check for operand_equal_p (lhs, rhs, 0) */
8822 /* Try a few strategies that may be cheaper than the general
8823 code at the end of the function, if the rhs is not known.
8824 The strategies are:
8825 - Call library function for 64-bit multiplication (complex)
8826 - Widen, if input arguments are sufficiently small
8827 - Determine overflow using wrapped result for addition/subtraction. */
8830 {
8831 /* Even for add/subtract double size to get another base type. */
8835 {
8841 }
8845 {
8851 check = build_binary_op
8858 return
8860 }
8863 {
8865 tree wrapped_expr
8871 /* Overflow when (rhs < 0) ^ (wrapped_expr < lhs)), for addition
8872 or when (rhs < 0) ^ (wrapped_expr > lhs) for subtraction. */
8873 check
8877 boolean_type_node,
8880 return
8882 }
8883 }
8886 {
8888 /* When rhs >= 0, overflow when lhs > type_max - rhs. */
8893 /* When rhs < 0, overflow when lhs < type_min - rhs. */
8900 /* When rhs >= 0, overflow when lhs < type_min + rhs. */
8905 /* When rhs < 0, overflow when lhs > type_max + rhs. */
8912 /* The check here is designed to be efficient if the rhs is constant,
8913 but it will work for any rhs by using integer division.
8914 Four different check expressions determine whether X * C overflows,
8915 depending on C.
8916 C == 0 => false
8917 C > 0 => X > type_max / C || X < type_min / C
8918 C == -1 => X == type_min
8919 C < -1 => X > type_min / C || X < type_max / C */
8924 check_pos
8927 rhs),
8930 boolean_type_node,
8933 boolean_type_node,
8936 check_neg
8941 type_min),
8944 boolean_type_node,
8947 boolean_type_node,
8953 }
8956 check_pos);
8959 }
8961 /* Emit code for a range check. GNU_EXPR is the expression to be checked,
8962 GNAT_RANGE_TYPE the gnat type or subtype containing the bounds against
8963 which we have to check. GNAT_NODE is the GNAT node conveying the source
8964 location for which the error should be signaled. */
8966 static tree
8968 {
8972 /* If GNU_EXPR has GNAT_RANGE_TYPE as its base type, no check is needed.
8973 This can for example happen when translating 'Val or 'Value. */
8977 /* Range checks can only be applied to types with ranges. */
8981 /* If GNU_EXPR has an integral type that is narrower than GNU_RANGE_TYPE,
8982 we can't do anything since we might be truncating the bounds. No
8983 check is needed in this case. */
8989 /* Checked expressions must be evaluated only once. */
8992 /* Note that the form of the check is
8993 (not (expr >= lo)) or (not (expr <= hi))
8994 the reason for this slightly convoluted form is that NaNs
8995 are not considered to be in range in the float case. */
8996 return emit_check
8998 invert_truthvalue
9002 TYPE_MIN_VALUE
9004 invert_truthvalue
9008 TYPE_MAX_VALUE
9011 }
9012 \f
9013 /* Emit code for an index check. GNU_ARRAY_OBJECT is the array object which
9014 we are about to index, GNU_EXPR is the index expression to be checked,
9015 GNU_LOW and GNU_HIGH are the lower and upper bounds against which GNU_EXPR
9016 has to be checked. Note that for index checking we cannot simply use the
9017 emit_range_check function (although very similar code needs to be generated
9018 in both cases) since for index checking the array type against which we are
9019 checking the indices may be unconstrained and consequently we need to get
9020 the actual index bounds from the array object itself (GNU_ARRAY_OBJECT).
9021 The place where we need to do that is in subprograms having unconstrained
9022 array formal parameters. GNAT_NODE is the GNAT node conveying the source
9023 location for which the error should be signaled. */
9025 static tree
9028 {
9029 tree gnu_expr_check;
9031 /* Checked expressions must be evaluated only once. */
9034 /* Must do this computation in the base type in case the expression's
9035 type is an unsigned subtypes. */
9038 /* If GNU_LOW or GNU_HIGH are a PLACEHOLDER_EXPR, qualify them by
9039 the object we are handling. */
9043 return emit_check
9046 gnu_expr_check,
9048 gnu_low)),
9050 gnu_expr_check,
9052 gnu_high))),
9054 }
9055 \f
9056 /* GNU_COND contains the condition corresponding to an index, overflow or
9057 range check of value GNU_EXPR. Build a COND_EXPR that returns GNU_EXPR
9058 if GNU_COND is false and raises a CONSTRAINT_ERROR if GNU_COND is true.
9059 REASON is the code that says why the exception is raised. GNAT_NODE is
9060 the node conveying the source location for which the error should be
9061 signaled.
9063 We used to propagate TREE_SIDE_EFFECTS from GNU_EXPR to the COND_EXPR,
9064 overwriting the setting inherited from the call statement, on the ground
9065 that the expression need not be evaluated just for the check. However
9066 that's incorrect because, in the GCC type system, its value is presumed
9067 to be valid so its comparison against the type bounds always yields true
9068 and, therefore, could be done without evaluating it; given that it can
9069 be a computation that overflows the bounds, the language may require the
9070 check to fail and thus the expression to be evaluated in this case. */
9072 static tree
9074 {
9075 tree gnu_call
9077 return
9081 gnu_expr);
9082 }
9083 \f
9084 /* Return an expression that converts GNU_EXPR to GNAT_TYPE, doing overflow
9085 checks if OVERFLOW_P is true and range checks if RANGE_P is true.
9086 GNAT_TYPE is known to be an integral type. If TRUNCATE_P true, do a
9087 float to integer conversion with truncation; otherwise round.
9088 GNAT_NODE is the GNAT node conveying the source location for which the
9089 error should be signaled. */
9091 static tree
9094 {
9101 /* If we are not doing any checks, the output is an integral type and the
9102 input is not a floating-point type, just do the conversion. This is
9103 required for packed array types and is simpler in all cases anyway. */
9105 && !overflowp
9110 /* First convert the expression to its base type. This
9111 will never generate code, but makes the tests below much simpler.
9112 But don't do this if converting from an integer type to an unconstrained
9113 array type since then we need to get the bounds from the original
9114 (unpacked) type. */
9118 /* If overflow checks are requested, we need to be sure the result will
9119 fit in the output base type. But don't do this if the input
9120 is integer and the output floating-point. */
9123 {
9124 /* Ensure GNU_EXPR only gets evaluated once. */
9132 /* Convert the lower bounds to signed types, so we're sure we're
9133 comparing them properly. Likewise, convert the upper bounds
9134 to unsigned types. */
9148 /* Check each bound separately and only if the result bound
9149 is tighter than the bound on the input type. Note that all the
9150 types are base types, so the bounds must be constant. Also,
9151 the comparison is done in the base type of the input, which
9152 always has the proper signedness. First check for input
9153 integer (which means output integer), output float (which means
9154 both float), or mixed, in which case we always compare.
9155 Note that we have to do the comparison which would *fail* in the
9156 case of an error since if it's an FP comparison and one of the
9157 values is a NaN or Inf, the comparison will fail. */
9164 gnu_cond
9165 = invert_truthvalue
9168 gnu_out_lb)));
9176 gnu_cond
9178 invert_truthvalue
9180 gnu_input,
9182 gnu_out_ub))));
9187 }
9189 /* Now convert to the result base type. If this is a non-truncating
9190 float-to-integer conversion, round. */
9194 {
9200 /* The following calculations depend on proper rounding to even
9201 of each arithmetic operation. In order to prevent excess
9202 precision from spoiling this property, use the widest hardware
9203 floating-point type if FP_ARITH_MAY_WIDEN is true. */
9204 calc_type
9207 /* Compute the exact value calc_type'Pred (0.5) at compile time. */
9214 /* If the input is strictly negative, subtract this value
9215 and otherwise add it from the input. For 0.5, the result
9216 is exactly between 1.0 and the machine number preceding 1.0
9217 (for calc_type). Since the last bit of 1.0 is even, this 0.5
9218 will round to 1.0, while all other number with an absolute
9219 value less than 0.5 round to 0.0. For larger numbers exactly
9220 halfway between integers, rounding will always be correct as
9221 the true mathematical result will be closer to the higher
9222 integer compared to the lower one. So, this constant works
9223 for all floating-point numbers.
9225 The reason to use the same constant with subtract/add instead
9226 of a positive and negative constant is to allow the comparison
9227 to be scheduled in parallel with retrieval of the constant and
9228 conversion of the input to the calc_type (if necessary). */
9233 gnu_comp
9235 gnu_add_pred_half
9237 gnu_subtract_pred_half
9241 }
9247 else
9250 /* Finally, do the range check if requested. Note that if the result type
9251 is a modular type, the range check is actually an overflow check. */
9258 }
9259 \f
9260 /* Return true if GNU_EXPR can be directly addressed. This is the case
9261 unless it is an expression involving computation or if it involves a
9262 reference to a bitfield or to an object not sufficiently aligned for
9263 its type. If GNU_TYPE is non-null, return true only if GNU_EXPR can
9264 be directly addressed as an object of this type.
9266 *** Notes on addressability issues in the Ada compiler ***
9268 This predicate is necessary in order to bridge the gap between Gigi
9269 and the middle-end about addressability of GENERIC trees. A tree
9270 is said to be addressable if it can be directly addressed, i.e. if
9271 its address can be taken, is a multiple of the type's alignment on
9272 strict-alignment architectures and returns the first storage unit
9273 assigned to the object represented by the tree.
9275 In the C family of languages, everything is in practice addressable
9276 at the language level, except for bit-fields. This means that these
9277 compilers will take the address of any tree that doesn't represent
9278 a bit-field reference and expect the result to be the first storage
9279 unit assigned to the object. Even in cases where this will result
9280 in unaligned accesses at run time, nothing is supposed to be done
9281 and the program is considered as erroneous instead (see PR c/18287).
9283 The implicit assumptions made in the middle-end are in keeping with
9284 the C viewpoint described above:
9285 - the address of a bit-field reference is supposed to be never
9286 taken; the compiler (generally) will stop on such a construct,
9287 - any other tree is addressable if it is formally addressable,
9288 i.e. if it is formally allowed to be the operand of ADDR_EXPR.
9290 In Ada, the viewpoint is the opposite one: nothing is addressable
9291 at the language level unless explicitly declared so. This means
9292 that the compiler will both make sure that the trees representing
9293 references to addressable ("aliased" in Ada parlance) objects are
9294 addressable and make no real attempts at ensuring that the trees
9295 representing references to non-addressable objects are addressable.
9297 In the first case, Ada is effectively equivalent to C and handing
9298 down the direct result of applying ADDR_EXPR to these trees to the
9299 middle-end works flawlessly. In the second case, Ada cannot afford
9300 to consider the program as erroneous if the address of trees that
9301 are not addressable is requested for technical reasons, unlike C;
9302 as a consequence, the Ada compiler must arrange for either making
9303 sure that this address is not requested in the middle-end or for
9304 compensating by inserting temporaries if it is requested in Gigi.
9306 The first goal can be achieved because the middle-end should not
9307 request the address of non-addressable trees on its own; the only
9308 exception is for the invocation of low-level block operations like
9309 memcpy, for which the addressability requirements are lower since
9310 the type's alignment can be disregarded. In practice, this means
9311 that Gigi must make sure that such operations cannot be applied to
9312 non-BLKmode bit-fields.
9314 The second goal is achieved by means of the addressable_p predicate,
9315 which computes whether a temporary must be inserted by Gigi when the
9316 address of a tree is requested; if so, the address of the temporary
9317 will be used in lieu of that of the original tree and some glue code
9318 generated to connect everything together. */
9320 static bool
9322 {
9323 /* For an integral type, the size of the actual type of the object may not
9324 be greater than that of the expected type, otherwise an indirect access
9325 in the latter type wouldn't correctly set all the bits of the object. */
9331 /* The size of the actual type of the object may not be smaller than that
9332 of the expected type, otherwise an indirect access in the latter type
9333 would be larger than the object. But only record types need to be
9334 considered in practice for this case. */
9341 {
9346 /* All DECLs are addressable: if they are in a register, we can force
9347 them to memory. */
9352 /* Taking the address of a dereference yields the original pointer. */
9357 /* Taking the address yields a pointer to the constant pool. */
9361 /* Taking the address of a static constructor yields a pointer to the
9362 tree constant pool. */
9374 /* All rvalues are deemed addressable since taking their address will
9375 force a temporary to be created by the middle-end. */
9379 /* The address of a compound expression is that of its 2nd operand. */
9383 /* We accept &COND_EXPR as soon as both operands are addressable and
9384 expect the outcome to be the address of the selected operand. */
9390 /* Even with DECL_BIT_FIELD cleared, we have to ensure that
9391 the field is sufficiently aligned, in case it is subject
9392 to a pragma Component_Alignment. But we don't need to
9393 check the alignment of the containing record, as it is
9394 guaranteed to be not smaller than that of its most
9395 aligned field that is not a bit-field. */
9396 && (!STRICT_ALIGNMENT
9399 /* The field of a padding record is always addressable. */
9413 {
9414 /* This is addressable if we can avoid a copy. */
9418 && (!STRICT_ALIGNMENT
9423 && (!STRICT_ALIGNMENT
9429 }
9433 }
9434 }
9435 \f
9436 /* Do the processing for the declaration of a GNAT_ENTITY, a type. If
9437 a separate Freeze node exists, delay the bulk of the processing. Otherwise
9438 make a GCC type for GNAT_ENTITY and set up the correspondence. */
9440 void
9442 {
9443 tree gnu_old
9445 tree gnu_new;
9447 /* If we are to delay elaboration of this type, just do any
9448 elaborations needed for expressions within the declaration and
9449 make a dummy type entry for this node and its Full_View (if
9450 any) in case something points to it. Don't do this if it
9451 has already been done (the only way that can happen is if
9452 the private completion is also delayed). */
9458 {
9462 {
9467 {
9471 }
9472 }
9475 }
9477 /* If we saved away a dummy type for this node it means that this
9478 made the type that corresponds to the full type of an incomplete
9479 type. Clear that type for now and then update the type in the
9480 pointers. */
9482 {
9487 }
9489 /* Now fully elaborate the type. */
9493 /* If we have an old type and we've made pointers to this type, update those
9494 pointers. If this is a Taft amendment type in the main unit, we need to
9495 mark the type as used since other units referencing it don't see the full
9496 declaration and, therefore, cannot mark it as used themselves. */
9498 {
9503 }
9505 /* If this is a record type corresponding to a task or protected type
9506 that is a completion of an incomplete type, perform a similar update
9507 on the type. ??? Including protected types here is a guess. */
9511 {
9512 tree gnu_task_old
9522 }
9523 }
9524 \f
9525 /* GNAT_ENTITY is the type of the resulting constructor, GNAT_ASSOC is the
9526 front of the Component_Associations of an N_Aggregate and GNU_TYPE is the
9527 GCC type of the corresponding record type. Return the CONSTRUCTOR. */
9529 static tree
9531 {
9534 /* We test for GNU_FIELD being empty in the case where a variant
9535 was the last thing since we don't take things off GNAT_ASSOC in
9536 that case. We check GNAT_ASSOC in case we have a variant, but it
9537 has no fields. */
9540 {
9545 /* The expander is supposed to put a single component selector name
9546 in every record component association. */
9549 /* Ignore fields that have Corresponding_Discriminants since we'll
9550 be setting that field in the parent. */
9555 /* Also ignore discriminants of Unchecked_Unions. */
9560 /* Before assigning a value in an aggregate make sure range checks
9561 are done if required. Then convert to the type of the field. */
9567 /* Add the field and expression to the list. */
9569 }
9574 {
9575 /* Verify that every entry in GNU_LIST was used. */
9578 }
9581 }
9583 /* Build a possibly nested constructor for array aggregates. GNAT_EXPR is
9584 the first element of an array aggregate. It may itself be an aggregate.
9585 GNU_ARRAY_TYPE is the GCC type corresponding to the array aggregate.
9586 GNAT_COMPONENT_TYPE is the type of the array component; it is needed
9587 for range checking. */
9589 static tree
9591 Entity_Id gnat_component_type)
9592 {
9594 tree gnu_expr;
9598 {
9599 /* If the expression is itself an array aggregate then first build the
9600 innermost constructor if it is part of our array (multi-dimensional
9601 case). */
9607 gnat_component_type);
9608 else
9609 {
9612 /* Before assigning the element to the array, make sure it is
9613 in range. */
9616 }
9623 integer_one_node));
9624 }
9627 }
9628 \f
9629 /* Subroutine of assoc_to_constructor: VALUES is a list of field associations,
9630 some of which are from RECORD_TYPE. Return a CONSTRUCTOR consisting of the
9631 associations that are from RECORD_TYPE. If we see an internal record, make
9632 a recursive call to fill it in as well. */
9634 static tree
9636 {
9641 {
9644 /* _Parent is an internal field, but may have values in the aggregate,
9645 so check for values first. */
9647 {
9650 }
9653 {
9658 }
9659 else
9660 /* If we have a record subtype, the names will match, but not the
9661 actual FIELD_DECLs. */
9664 {
9667 }
9673 }
9676 }
9677 \f
9678 /* Process a N_Validate_Unchecked_Conversion node. */
9680 static void
9682 {
9686 /* If the target is a pointer type, see if we are either converting from a
9687 non-pointer or from a pointer to a type with a different alias set and
9688 warn if so, unless the pointer has been marked to alias everything. */
9691 {
9701 target_alias_set)))
9702 {
9706 gnat_node);
9709 }
9710 }
9712 /* Likewise if the target is a fat pointer type, but we have no mechanism to
9713 mitigate the problem in this case, so we unconditionally warn. */
9715 {
9716 tree gnu_source_desig_type
9720 tree gnu_target_desig_type
9727 target_alias_set)))
9728 {
9732 gnat_node);
9733 }
9734 }
9735 }
9736 \f
9737 /* EXP is to be treated as an array or record. Handle the cases when it is
9738 an access object and perform the required dereferences. */
9740 static tree
9742 {
9743 /* If the type is a pointer, dereference it. */
9748 /* If we got a padded type, remove it too. */
9753 }
9754 \f
9755 /* Convert SLOC into LOCUS. Return true if SLOC corresponds to a source code
9756 location and false if it doesn't. If CLEAR_COLUMN is true, set the column
9757 information to 0. */
9759 bool
9761 {
9766 {
9769 }
9776 /* We can have zero if pragma Source_Reference is in effect. */
9780 /* Translate the location. */
9785 }
9787 /* Similar to set_expr_location, but start with the Sloc of GNAT_NODE and
9788 don't do anything if it doesn't correspond to a source location. And,
9789 if CLEAR_COLUMN is true, set the column information to 0. */
9791 static void
9793 {
9794 location_t locus;
9800 }
9802 /* More elaborate version of set_expr_location_from_node to be used in more
9803 general contexts, for example the result of the translation of a generic
9804 GNAT node. */
9806 static void
9808 {
9809 /* Set the location information on the node if it is a real expression.
9810 References can be reused for multiple GNAT nodes and they would get
9811 the location information of their last use. Also make sure not to
9812 overwrite an existing location as it is probably more precise. */
9815 {
9816 CASE_CONVERT:
9825 /* ... fall through ... */
9829 {
9832 }
9834 }
9835 }
9837 /* Set the end_locus information for GNU_NODE, if any, from an explicit end
9838 location associated with GNAT_NODE or GNAT_NODE itself, whichever makes
9839 most sense. Return true if a sensible assignment was performed. */
9841 static bool
9843 {
9844 Node_Id gnat_end_label;
9845 location_t end_locus;
9847 /* Pick the GNAT node of which we'll take the sloc to assign to the GCC node
9848 end_locus when there is one. We consider only GNAT nodes with a possible
9849 End_Label attached. If the End_Label actually was unassigned, fallback
9850 on the original node. We'd better assign an explicit sloc associated with
9851 the outer construct in any case. */
9854 {
9867 }
9872 /* Some expanded subprograms have neither an End_Label nor a Sloc
9873 attached. Notify that to callers. For a block statement with no
9874 End_Label, clear column information, so that the tree for a
9875 transient block does not receive the sloc of a source condition. */
9882 {
9893 }
9894 }
9895 \f
9896 /* Return a colon-separated list of encodings contained in encoded Ada
9897 name. */
9901 {
9905 }
9907 /* Extract the Ada name from an encoded name. */
9911 {
9915 }
9916 \f
9917 /* Post an error message. MSG is the error message, properly annotated.
9918 NODE is the node at which to post the error and the node to use for the
9919 '&' substitution. */
9921 void
9923 {
9924 String_Template temp;
9925 String_Pointer sp;
9935 }
9937 /* Similar to post_error, but NODE is the node at which to post the error and
9938 ENT is the node to use for the '&' substitution. */
9940 void
9942 {
9943 String_Template temp;
9944 String_Pointer sp;
9954 }
9956 /* Similar to post_error_ne, but NUM is the number to use for the '^'. */
9958 void
9960 {
9963 }
9965 /* Similar to post_error_ne, but T is a GCC tree representing the number to
9966 write. If T represents a constant, the text inside curly brackets in
9967 MSG will be output (presumably including a '^'). Otherwise it will not
9968 be output and the text inside square brackets will be output instead. */
9970 void
9972 {
9979 {
9982 }
9983 else
9987 {
9993 ;
9994 else
9996 }
10001 }
10003 /* Similar to post_error_ne_tree, but NUM is a second integer to write. */
10005 void
10008 {
10011 }
10012 \f
10013 /* Initialize the table that maps GNAT codes to GCC codes for simple
10014 binary and unary operations. */
10016 static void
10018 {
10044 }
10046 /* Return a label to branch to for the exception type in KIND or NULL_TREE
10047 if none. */
10049 tree
10051 {
10058 else
10060 }
10062 /* Return the decl for the current elaboration procedure. */
10064 tree
10066 {
10068 }