1 /* Perform optimizations on tree structure.
2 Copyright (C) 1998-2018 Free Software Foundation, Inc.
3 Written by Mark Michell (mark@codesourcery.com).
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
26 #include "stringpool.h"
29 #include "tree-inline.h"
30 #include "tree-iterator.h"
34 static void update_cloned_parm (tree, tree, bool);
36 /* CLONED_PARM is a copy of CLONE, generated for a cloned constructor
37 or destructor. Update it to ensure that the source-position for
38 the cloned parameter matches that for the original, and that the
39 debugging generation code will be able to find the original PARM. */
42 update_cloned_parm (tree parm, tree cloned_parm, bool first)
44 DECL_ABSTRACT_ORIGIN (cloned_parm) = parm;
46 /* We may have taken its address. */
47 TREE_ADDRESSABLE (cloned_parm) = TREE_ADDRESSABLE (parm);
49 /* The definition might have different constness. */
50 TREE_READONLY (cloned_parm) = TREE_READONLY (parm);
52 TREE_USED (cloned_parm) = !first || TREE_USED (parm);
54 /* The name may have changed from the declaration. */
55 DECL_NAME (cloned_parm) = DECL_NAME (parm);
56 DECL_SOURCE_LOCATION (cloned_parm) = DECL_SOURCE_LOCATION (parm);
57 TREE_TYPE (cloned_parm) = TREE_TYPE (parm);
59 DECL_GIMPLE_REG_P (cloned_parm) = DECL_GIMPLE_REG_P (parm);
63 /* FN is a function in High GIMPLE form that has a complete body and no
64 CFG. CLONE is a function whose body is to be set to a copy of FN,
65 mapping argument declarations according to the ARG_MAP splay_tree. */
68 clone_body (tree clone, tree fn, void *arg_map)
73 /* Clone the body, as if we were making an inline call. But, remap
74 the parameters in the callee to the parameters of caller. */
75 memset (&id, 0, sizeof (id));
78 id.src_cfun = DECL_STRUCT_FUNCTION (fn);
79 id.decl_map = static_cast<hash_map<tree, tree> *> (arg_map);
81 id.copy_decl = copy_decl_no_change;
82 id.transform_call_graph_edges = CB_CGE_DUPLICATE;
83 id.transform_new_cfg = true;
84 id.transform_return_to_modify = false;
85 id.transform_lang_insert_block = NULL;
87 /* We're not inside any EH region. */
90 stmts = DECL_SAVED_TREE (fn);
91 walk_tree (&stmts, copy_tree_body_r, &id, NULL);
93 /* Also remap the initializer of any static variables so that they (in
94 particular, any label addresses) correspond to the base variant rather
95 than the abstract one. */
96 if (DECL_NAME (clone) == base_dtor_identifier
97 || DECL_NAME (clone) == base_ctor_identifier)
102 FOR_EACH_LOCAL_DECL (DECL_STRUCT_FUNCTION (fn), ix, decl)
103 walk_tree (&DECL_INITIAL (decl), copy_tree_body_r, &id, NULL);
106 append_to_statement_list_force (stmts, &DECL_SAVED_TREE (clone));
109 /* DELETE_DTOR is a delete destructor whose body will be built.
110 COMPLETE_DTOR is the corresponding complete destructor. */
113 build_delete_destructor_body (tree delete_dtor, tree complete_dtor)
115 tree parm = DECL_ARGUMENTS (delete_dtor);
116 tree virtual_size = cxx_sizeof (current_class_type);
118 /* Call the corresponding complete destructor. */
119 gcc_assert (complete_dtor);
120 tree call_dtor = build_cxx_call (complete_dtor, 1, &parm,
121 tf_warning_or_error);
123 /* Call the delete function. */
124 tree call_delete = build_op_delete_call (DELETE_EXPR, current_class_ptr,
127 /*placement=*/NULL_TREE,
128 /*alloc_fn=*/NULL_TREE,
129 tf_warning_or_error);
131 /* Operator delete must be called, whether or not the dtor throws. */
132 add_stmt (build2 (TRY_FINALLY_EXPR, void_type_node, call_dtor, call_delete));
134 /* Return the address of the object. */
135 if (targetm.cxx.cdtor_returns_this ())
137 tree val = DECL_ARGUMENTS (delete_dtor);
138 val = build2 (MODIFY_EXPR, TREE_TYPE (val),
139 DECL_RESULT (delete_dtor), val);
140 add_stmt (build_stmt (0, RETURN_EXPR, val));
144 /* Return name of comdat group for complete and base ctor (or dtor)
145 that have the same body. If dtor is virtual, deleting dtor goes
146 into this comdat group as well. */
149 cdtor_comdat_group (tree complete, tree base)
151 tree complete_name = DECL_ASSEMBLER_NAME (complete);
152 tree base_name = DECL_ASSEMBLER_NAME (base);
155 bool diff_seen = false;
157 gcc_assert (IDENTIFIER_LENGTH (complete_name)
158 == IDENTIFIER_LENGTH (base_name));
159 grp_name = XALLOCAVEC (char, IDENTIFIER_LENGTH (complete_name) + 1);
160 p = IDENTIFIER_POINTER (complete_name);
161 q = IDENTIFIER_POINTER (base_name);
162 for (idx = 0; idx < IDENTIFIER_LENGTH (complete_name); idx++)
163 if (p[idx] == q[idx])
164 grp_name[idx] = p[idx];
167 gcc_assert (!diff_seen
169 && (p[idx - 1] == 'C' || p[idx - 1] == 'D'
170 || p[idx - 1] == 'I')
176 grp_name[idx] = '\0';
177 gcc_assert (diff_seen);
178 return get_identifier (grp_name);
181 /* Returns true iff we can make the base and complete [cd]tor aliases of
182 the same symbol rather than separate functions. */
185 can_alias_cdtor (tree fn)
187 /* If aliases aren't supported by the assembler, fail. */
188 if (!TARGET_SUPPORTS_ALIASES)
191 /* We can't use an alias if there are virtual bases. */
192 if (CLASSTYPE_VBASECLASSES (DECL_CONTEXT (fn)))
194 /* ??? Why not use aliases with -frepo? */
195 if (flag_use_repository)
197 gcc_assert (DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
198 || DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn));
199 /* Don't use aliases for weak/linkonce definitions unless we can put both
200 symbols in the same COMDAT group. */
201 return (DECL_INTERFACE_KNOWN (fn)
202 && (SUPPORTS_ONE_ONLY || !DECL_WEAK (fn))
203 && (!DECL_ONE_ONLY (fn)
204 || (HAVE_COMDAT_GROUP && DECL_WEAK (fn))));
207 /* FN is a [cd]tor, fns is a pointer to an array of length 3. Fill fns
208 with pointers to the base, complete, and deleting variants. */
211 populate_clone_array (tree fn, tree *fns)
219 /* Look for the complete destructor which may be used to build the
220 delete destructor. */
221 FOR_EACH_CLONE (clone, fn)
222 if (DECL_NAME (clone) == complete_dtor_identifier
223 || DECL_NAME (clone) == complete_ctor_identifier)
225 else if (DECL_NAME (clone) == base_dtor_identifier
226 || DECL_NAME (clone) == base_ctor_identifier)
228 else if (DECL_NAME (clone) == deleting_dtor_identifier)
234 /* FN is a constructor or destructor, and there are FUNCTION_DECLs
235 cloned from it nearby. Instead of cloning this body, leave it
236 alone and create tiny one-call bodies for the cloned
237 FUNCTION_DECLs. These clones are sibcall candidates, and their
238 resulting code will be very thunk-esque. */
241 maybe_thunk_body (tree fn, bool force)
243 tree bind, block, call, clone, clone_result, fn_parm, fn_parm_typelist;
244 tree last_arg, modify, *args;
245 int parmno, vtt_parmno, max_parms;
248 if (!force && !flag_declone_ctor_dtor)
251 /* If function accepts variable arguments, give up. */
252 last_arg = tree_last (TYPE_ARG_TYPES (TREE_TYPE (fn)));
253 if (last_arg != void_list_node)
256 /* If we got this far, we've decided to turn the clones into thunks. */
258 /* We're going to generate code for fn, so it is no longer "abstract."
259 Also make the unified ctor/dtor private to either the translation unit
260 (for non-vague linkage ctors) or the COMDAT group (otherwise). */
262 populate_clone_array (fn, fns);
264 /* Can happen during error recovery (c++/71464). */
265 if (!fns[0] || !fns[1])
268 /* Don't use thunks if the base clone omits inherited parameters. */
269 if (ctor_omit_inherited_parms (fns[0]))
272 DECL_ABSTRACT_P (fn) = false;
275 TREE_PUBLIC (fn) = false;
276 DECL_EXTERNAL (fn) = false;
277 DECL_INTERFACE_KNOWN (fn) = true;
279 else if (HAVE_COMDAT_GROUP)
281 /* At eof, defer creation of mangling aliases temporarily. */
282 bool save_defer_mangling_aliases = defer_mangling_aliases;
283 defer_mangling_aliases = true;
284 tree comdat_group = cdtor_comdat_group (fns[1], fns[0]);
285 defer_mangling_aliases = save_defer_mangling_aliases;
286 cgraph_node::get_create (fns[0])->set_comdat_group (comdat_group);
287 cgraph_node::get_create (fns[1])->add_to_same_comdat_group
288 (cgraph_node::get_create (fns[0]));
289 symtab_node::get (fn)->add_to_same_comdat_group
290 (symtab_node::get (fns[0]));
292 /* If *[CD][12]* dtors go into the *[CD]5* comdat group and dtor is
293 virtual, it goes into the same comdat group as well. */
294 cgraph_node::get_create (fns[2])->add_to_same_comdat_group
295 (symtab_node::get (fns[0]));
296 /* Emit them now that the thunks are same comdat group aliases. */
297 if (!save_defer_mangling_aliases)
298 generate_mangling_aliases ();
299 TREE_PUBLIC (fn) = false;
300 DECL_EXTERNAL (fn) = false;
301 DECL_INTERFACE_KNOWN (fn) = true;
302 /* function_and_variable_visibility doesn't want !PUBLIC decls to
303 have these flags set. */
304 DECL_WEAK (fn) = false;
305 DECL_COMDAT (fn) = false;
308 /* Find the vtt_parm, if present. */
309 for (vtt_parmno = -1, parmno = 0, fn_parm = DECL_ARGUMENTS (fn);
311 ++parmno, fn_parm = TREE_CHAIN (fn_parm))
313 if (DECL_ARTIFICIAL (fn_parm)
314 && DECL_NAME (fn_parm) == vtt_parm_identifier)
316 /* Compensate for removed in_charge parameter. */
322 /* Allocate an argument buffer for build_cxx_call().
323 Make sure it is large enough for any of the clones. */
325 FOR_EACH_CLONE (clone, fn)
327 int length = list_length (DECL_ARGUMENTS (fn));
328 if (length > max_parms)
331 args = XALLOCAVEC (tree, max_parms);
333 /* We know that any clones immediately follow FN in TYPE_FIELDS. */
334 FOR_EACH_CLONE (clone, fn)
338 /* If we've already generated a body for this clone, avoid
339 duplicating it. (Is it possible for a clone-list to grow after we
341 if (DECL_SAVED_TREE (clone) || TREE_ASM_WRITTEN (clone))
344 /* Start processing the function. */
345 start_preparsed_function (clone, NULL_TREE, SF_PRE_PARSED);
349 for (clone_parm = DECL_ARGUMENTS (clone); clone_parm;
350 clone_parm = TREE_CHAIN (clone_parm))
351 DECL_ABSTRACT_ORIGIN (clone_parm) = NULL_TREE;
352 /* Build the delete destructor by calling complete destructor and
354 build_delete_destructor_body (clone, fns[1]);
358 /* Walk parameter lists together, creating parameter list for
359 call to original function. */
361 fn_parm = DECL_ARGUMENTS (fn),
362 fn_parm_typelist = TYPE_ARG_TYPES (TREE_TYPE (fn)),
363 clone_parm = DECL_ARGUMENTS (clone);
366 fn_parm = TREE_CHAIN (fn_parm))
368 if (parmno == vtt_parmno && ! DECL_HAS_VTT_PARM_P (clone))
370 gcc_assert (fn_parm_typelist);
371 /* Clobber argument with formal parameter type. */
373 = convert (TREE_VALUE (fn_parm_typelist),
376 else if (parmno == 1 && DECL_HAS_IN_CHARGE_PARM_P (fn))
379 = copy_node (in_charge_arg_for_name (DECL_NAME (clone)));
380 args[parmno] = in_charge;
382 /* Map other parameters to their equivalents in the cloned
386 gcc_assert (clone_parm);
387 DECL_ABSTRACT_ORIGIN (clone_parm) = NULL;
388 args[parmno] = clone_parm;
389 clone_parm = TREE_CHAIN (clone_parm);
391 if (fn_parm_typelist)
392 fn_parm_typelist = TREE_CHAIN (fn_parm_typelist);
395 /* We built this list backwards; fix now. */
397 call = build_cxx_call (fn, parmno, args, tf_warning_or_error);
398 /* Arguments passed to the thunk by invisible reference should
399 be transmitted to the callee unchanged. Do not create a
400 temporary and invoke the copy constructor. The thunking
401 transformation must not introduce any constructor calls. */
402 CALL_FROM_THUNK_P (call) = 1;
403 block = make_node (BLOCK);
404 if (targetm.cxx.cdtor_returns_this ())
406 clone_result = DECL_RESULT (clone);
407 modify = build2 (MODIFY_EXPR, TREE_TYPE (clone_result),
409 modify = build1 (RETURN_EXPR, void_type_node, modify);
416 bind = c_build_bind_expr (DECL_SOURCE_LOCATION (clone),
417 block, cur_stmt_list);
418 DECL_SAVED_TREE (clone) = push_stmt_list ();
422 DECL_ABSTRACT_ORIGIN (clone) = NULL;
423 expand_or_defer_fn (finish_function (/*inline_p=*/false));
428 /* FN is a function that has a complete body. Clone the body as
429 necessary. Returns nonzero if there's no longer any need to
430 process the main body. */
433 maybe_clone_body (tree fn)
435 tree comdat_group = NULL_TREE;
440 bool need_alias = false;
442 /* We only clone constructors and destructors. */
443 if (!DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
444 && !DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn))
447 populate_clone_array (fn, fns);
449 /* Remember if we can't have multiple clones for some reason. We need to
450 check this before we remap local static initializers in clone_body. */
451 if (!tree_versionable_function_p (fn))
454 /* We know that any clones immediately follow FN in the TYPE_FIELDS
456 push_to_top_level ();
457 for (idx = 0; idx < 3; idx++)
466 /* Update CLONE's source position information to match FN's. */
467 DECL_SOURCE_LOCATION (clone) = DECL_SOURCE_LOCATION (fn);
468 DECL_DECLARED_INLINE_P (clone) = DECL_DECLARED_INLINE_P (fn);
469 DECL_DECLARED_CONSTEXPR_P (clone) = DECL_DECLARED_CONSTEXPR_P (fn);
470 DECL_COMDAT (clone) = DECL_COMDAT (fn);
471 DECL_WEAK (clone) = DECL_WEAK (fn);
473 /* We don't copy the comdat group from fn to clone because the assembler
474 name of fn was corrupted by write_mangled_name by adding *INTERNAL*
475 to it. By doing so, it also corrupted the comdat group. */
476 if (DECL_ONE_ONLY (fn))
477 cgraph_node::get_create (clone)->set_comdat_group (cxx_comdat_group (clone));
478 DECL_USE_TEMPLATE (clone) = DECL_USE_TEMPLATE (fn);
479 DECL_EXTERNAL (clone) = DECL_EXTERNAL (fn);
480 DECL_INTERFACE_KNOWN (clone) = DECL_INTERFACE_KNOWN (fn);
481 DECL_NOT_REALLY_EXTERN (clone) = DECL_NOT_REALLY_EXTERN (fn);
482 TREE_PUBLIC (clone) = TREE_PUBLIC (fn);
483 DECL_VISIBILITY (clone) = DECL_VISIBILITY (fn);
484 DECL_VISIBILITY_SPECIFIED (clone) = DECL_VISIBILITY_SPECIFIED (fn);
485 DECL_DLLIMPORT_P (clone) = DECL_DLLIMPORT_P (fn);
486 DECL_ATTRIBUTES (clone) = copy_list (DECL_ATTRIBUTES (fn));
487 DECL_DISREGARD_INLINE_LIMITS (clone) = DECL_DISREGARD_INLINE_LIMITS (fn);
488 set_decl_section_name (clone, DECL_SECTION_NAME (fn));
490 /* Adjust the parameter names and locations. */
491 parm = DECL_ARGUMENTS (fn);
492 clone_parm = DECL_ARGUMENTS (clone);
493 /* Update the `this' parameter, which is always first. */
494 update_cloned_parm (parm, clone_parm, first);
495 parm = DECL_CHAIN (parm);
496 clone_parm = DECL_CHAIN (clone_parm);
497 if (DECL_HAS_IN_CHARGE_PARM_P (fn))
498 parm = DECL_CHAIN (parm);
499 if (DECL_HAS_VTT_PARM_P (fn))
500 parm = DECL_CHAIN (parm);
501 if (DECL_HAS_VTT_PARM_P (clone))
502 clone_parm = DECL_CHAIN (clone_parm);
503 for (; parm && clone_parm;
504 parm = DECL_CHAIN (parm), clone_parm = DECL_CHAIN (clone_parm))
505 /* Update this parameter. */
506 update_cloned_parm (parm, clone_parm, first);
509 bool can_alias = can_alias_cdtor (fn);
511 /* If we decide to turn clones into thunks, they will branch to fn.
512 Must have original function available to call. */
513 if (!can_alias && maybe_thunk_body (fn, need_alias))
515 pop_from_top_level ();
516 /* We still need to emit the original function. */
520 /* Emit the DWARF1 abstract instance. */
521 (*debug_hooks->deferred_inline_function) (fn);
523 /* We know that any clones immediately follow FN in the TYPE_FIELDS. */
524 for (idx = 0; idx < 3; idx++)
529 hash_map<tree, tree> *decl_map;
536 /* Start processing the function. */
537 start_preparsed_function (clone, NULL_TREE, SF_PRE_PARSED);
539 /* Tell cgraph if both ctors or both dtors are known to have
544 && cgraph_node::get_create (fns[0])->create_same_body_alias
548 if (DECL_ONE_ONLY (fns[0]))
550 /* For comdat base and complete cdtors put them
551 into the same, *[CD]5* comdat group instead of
553 comdat_group = cdtor_comdat_group (fns[1], fns[0]);
554 cgraph_node::get_create (fns[0])->set_comdat_group (comdat_group);
555 if (symtab_node::get (clone)->same_comdat_group)
556 symtab_node::get (clone)->remove_from_same_comdat_group ();
557 symtab_node::get (clone)->add_to_same_comdat_group
558 (symtab_node::get (fns[0]));
562 /* Build the delete destructor by calling complete destructor
563 and delete function. */
566 build_delete_destructor_body (clone, fns[1]);
567 /* If *[CD][12]* dtors go into the *[CD]5* comdat group and dtor is
568 virtual, it goes into the same comdat group as well. */
570 cgraph_node::get_create (clone)->add_to_same_comdat_group
571 (symtab_node::get (fns[0]));
574 /* No need to populate body. */ ;
577 /* If we can't have multiple copies of FN (say, because there's a
578 static local initialized with the address of a label), we need
579 to use an alias for the complete variant. */
580 if (idx == 1 && need_alias)
582 if (DECL_STRUCT_FUNCTION (fn)->cannot_be_copied_set)
583 sorry (DECL_STRUCT_FUNCTION (fn)->cannot_be_copied_reason, fn);
585 sorry ("making multiple clones of %qD", fn);
588 /* Remap the parameters. */
589 decl_map = new hash_map<tree, tree>;
591 parm = DECL_ARGUMENTS (fn),
592 clone_parm = DECL_ARGUMENTS (clone);
595 parm = DECL_CHAIN (parm))
597 /* Map the in-charge parameter to an appropriate constant. */
598 if (DECL_HAS_IN_CHARGE_PARM_P (fn) && parmno == 1)
601 in_charge = in_charge_arg_for_name (DECL_NAME (clone));
602 decl_map->put (parm, in_charge);
604 else if (DECL_ARTIFICIAL (parm)
605 && DECL_NAME (parm) == vtt_parm_identifier)
607 /* For a subobject constructor or destructor, the next
608 argument is the VTT parameter. Remap the VTT_PARM
609 from the CLONE to this parameter. */
610 if (DECL_HAS_VTT_PARM_P (clone))
612 DECL_ABSTRACT_ORIGIN (clone_parm) = parm;
613 decl_map->put (parm, clone_parm);
614 clone_parm = DECL_CHAIN (clone_parm);
616 /* Otherwise, map the VTT parameter to `NULL'. */
620 = fold_convert (TREE_TYPE (parm), null_pointer_node);
621 decl_map->put (parm, t);
624 /* Map other parameters to their equivalents in the cloned
631 replacement = clone_parm;
632 clone_parm = DECL_CHAIN (clone_parm);
636 /* Inheriting ctors can omit parameters from the base
637 clone. Replace them with null lvalues. */
638 tree reftype = build_reference_type (TREE_TYPE (parm));
639 replacement = fold_convert (reftype, null_pointer_node);
640 replacement = convert_from_reference (replacement);
642 decl_map->put (parm, replacement);
646 if (targetm.cxx.cdtor_returns_this ())
648 parm = DECL_RESULT (fn);
649 clone_parm = DECL_RESULT (clone);
650 decl_map->put (parm, clone_parm);
653 /* Clone the body. */
654 clone_body (clone, fn, decl_map);
660 /* The clone can throw iff the original function can throw. */
661 cp_function_chain->can_throw = !TREE_NOTHROW (fn);
663 /* Now, expand this function into RTL, if appropriate. */
664 finish_function (/*inline_p=*/false);
665 BLOCK_ABSTRACT_ORIGIN (DECL_INITIAL (clone)) = DECL_INITIAL (fn);
668 if (expand_or_defer_fn_1 (clone))
669 emit_associated_thunks (clone);
670 /* We didn't generate a body, so remove the empty one. */
671 DECL_SAVED_TREE (clone) = NULL_TREE;
674 expand_or_defer_fn (clone);
677 pop_from_top_level ();
679 /* We don't need to process the original function any further. */