1 /* Callgraph handling code.
2 Copyright (C) 2003-2014 Free Software Foundation, Inc.
3 Contributed by Jan Hubicka
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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"
28 #include "langhooks.h"
29 #include "diagnostic-core.h"
35 #include "gimple-expr.h"
37 #include "pointer-set.h"
39 /* List of hooks triggered on varpool_node events. */
40 struct varpool_node_hook_list
{
41 varpool_node_hook hook
;
43 struct varpool_node_hook_list
*next
;
46 /* List of hooks triggered when a node is removed. */
47 struct varpool_node_hook_list
*first_varpool_node_removal_hook
;
48 /* List of hooks triggered when an variable is inserted. */
49 struct varpool_node_hook_list
*first_varpool_variable_insertion_hook
;
51 /* Register HOOK to be called with DATA on each removed node. */
52 struct varpool_node_hook_list
*
53 varpool_add_node_removal_hook (varpool_node_hook hook
, void *data
)
55 struct varpool_node_hook_list
*entry
;
56 struct varpool_node_hook_list
**ptr
= &first_varpool_node_removal_hook
;
58 entry
= (struct varpool_node_hook_list
*) xmalloc (sizeof (*entry
));
68 /* Remove ENTRY from the list of hooks called on removing nodes. */
70 varpool_remove_node_removal_hook (struct varpool_node_hook_list
*entry
)
72 struct varpool_node_hook_list
**ptr
= &first_varpool_node_removal_hook
;
80 /* Call all node removal hooks. */
82 varpool_call_node_removal_hooks (varpool_node
*node
)
84 struct varpool_node_hook_list
*entry
= first_varpool_node_removal_hook
;
87 entry
->hook (node
, entry
->data
);
92 /* Register HOOK to be called with DATA on each inserted node. */
93 struct varpool_node_hook_list
*
94 varpool_add_variable_insertion_hook (varpool_node_hook hook
, void *data
)
96 struct varpool_node_hook_list
*entry
;
97 struct varpool_node_hook_list
**ptr
= &first_varpool_variable_insertion_hook
;
99 entry
= (struct varpool_node_hook_list
*) xmalloc (sizeof (*entry
));
109 /* Remove ENTRY from the list of hooks called on inserted nodes. */
111 varpool_remove_variable_insertion_hook (struct varpool_node_hook_list
*entry
)
113 struct varpool_node_hook_list
**ptr
= &first_varpool_variable_insertion_hook
;
115 while (*ptr
!= entry
)
121 /* Call all node insertion hooks. */
123 varpool_call_variable_insertion_hooks (varpool_node
*node
)
125 struct varpool_node_hook_list
*entry
= first_varpool_variable_insertion_hook
;
128 entry
->hook (node
, entry
->data
);
133 /* Allocate new callgraph node and insert it into basic data structures. */
136 varpool_create_empty_node (void)
138 varpool_node
*node
= ggc_cleared_alloc
<varpool_node
> ();
139 node
->type
= SYMTAB_VARIABLE
;
143 /* Return varpool node assigned to DECL. Create new one when needed. */
145 varpool_node_for_decl (tree decl
)
147 varpool_node
*node
= varpool_get_node (decl
);
148 gcc_checking_assert (TREE_CODE (decl
) == VAR_DECL
);
152 node
= varpool_create_empty_node ();
154 symtab_register_node (node
);
158 /* Remove node from the varpool. */
160 varpool_remove_node (varpool_node
*node
)
163 varpool_call_node_removal_hooks (node
);
164 symtab_unregister_node (node
);
166 /* Because we remove references from external functions before final compilation,
167 we may end up removing useful constructors.
168 FIXME: We probably want to trace boundaries better. */
169 if (cgraph_state
== CGRAPH_LTO_STREAMING
)
171 else if ((init
= ctor_for_folding (node
->decl
)) == error_mark_node
)
172 varpool_remove_initializer (node
);
174 DECL_INITIAL (node
->decl
) = init
;
178 /* Renove node initializer when it is no longer needed. */
180 varpool_remove_initializer (varpool_node
*node
)
182 if (DECL_INITIAL (node
->decl
)
183 && !DECL_IN_CONSTANT_POOL (node
->decl
)
184 /* Keep vtables for BINFO folding. */
185 && !DECL_VIRTUAL_P (node
->decl
)
186 /* FIXME: http://gcc.gnu.org/PR55395 */
187 && debug_info_level
== DINFO_LEVEL_NONE
188 /* When doing declaration merging we have duplicate
189 entries for given decl. Do not attempt to remove
190 the boides, or we will end up remiving
192 && cgraph_state
!= CGRAPH_LTO_STREAMING
)
193 DECL_INITIAL (node
->decl
) = error_mark_node
;
196 /* Dump given cgraph node. */
198 dump_varpool_node (FILE *f
, varpool_node
*node
)
200 dump_symtab_base (f
, node
);
201 fprintf (f
, " Availability: %s\n",
202 cgraph_function_flags_ready
203 ? cgraph_availability_names
[cgraph_variable_initializer_availability (node
)]
205 fprintf (f
, " Varpool flags:");
206 if (DECL_INITIAL (node
->decl
))
207 fprintf (f
, " initialized");
209 fprintf (f
, " output");
210 if (TREE_READONLY (node
->decl
))
211 fprintf (f
, " read-only");
212 if (ctor_for_folding (node
->decl
) != error_mark_node
)
213 fprintf (f
, " const-value-known");
215 fprintf (f
, " write-only");
219 /* Dump the variable pool. */
221 dump_varpool (FILE *f
)
225 fprintf (f
, "variable pool:\n\n");
226 FOR_EACH_VARIABLE (node
)
227 dump_varpool_node (f
, node
);
230 /* Dump the variable pool to stderr. */
235 dump_varpool (stderr
);
238 /* Given an assembler name, lookup node. */
240 varpool_node_for_asm (tree asmname
)
242 if (symtab_node
*node
= symtab_node_for_asm (asmname
))
243 return dyn_cast
<varpool_node
*> (node
);
248 /* Return if DECL is constant and its initial value is known (so we can do
249 constant folding using DECL_INITIAL (decl)).
250 Return ERROR_MARK_NODE when value is unknown. */
253 ctor_for_folding (tree decl
)
255 varpool_node
*node
, *real_node
;
258 if (TREE_CODE (decl
) != VAR_DECL
259 && TREE_CODE (decl
) != CONST_DECL
)
260 return error_mark_node
;
262 if (TREE_CODE (decl
) == CONST_DECL
263 || DECL_IN_CONSTANT_POOL (decl
))
264 return DECL_INITIAL (decl
);
266 if (TREE_THIS_VOLATILE (decl
))
267 return error_mark_node
;
269 /* Do not care about automatic variables. Those are never initialized
270 anyway, because gimplifier exapnds the code. */
271 if (!TREE_STATIC (decl
) && !DECL_EXTERNAL (decl
))
273 gcc_assert (!TREE_PUBLIC (decl
));
274 return error_mark_node
;
277 gcc_assert (TREE_CODE (decl
) == VAR_DECL
);
279 node
= varpool_get_node (decl
);
282 real_node
= varpool_variable_node (node
);
283 real_decl
= real_node
->decl
;
288 /* See if we are dealing with alias.
289 In most cases alias is just alternative symbol pointing to a given
290 constructor. This allows us to use interposition rules of DECL
291 constructor of REAL_NODE. However weakrefs are special by being just
292 alternative name of their target (if defined). */
293 if (decl
!= real_decl
)
295 gcc_assert (!DECL_INITIAL (decl
)
296 || DECL_INITIAL (decl
) == error_mark_node
);
297 if (lookup_attribute ("weakref", DECL_ATTRIBUTES (decl
)))
299 node
= varpool_alias_target (node
);
304 /* Vtables are defined by their types and must match no matter of interposition
306 if (DECL_VIRTUAL_P (real_decl
))
308 gcc_checking_assert (TREE_READONLY (real_decl
));
309 return DECL_INITIAL (real_decl
);
312 /* If there is no constructor, we have nothing to do. */
313 if (DECL_INITIAL (real_decl
) == error_mark_node
)
314 return error_mark_node
;
316 /* Non-readonly alias of readonly variable is also de-facto readonly,
317 because the variable itself is in readonly section.
318 We also honnor READONLY flag on alias assuming that user knows
320 if (!TREE_READONLY (decl
) && !TREE_READONLY (real_decl
))
321 return error_mark_node
;
323 /* Variables declared 'const' without an initializer
324 have zero as the initializer if they may not be
325 overridden at link or run time. */
326 if (!DECL_INITIAL (real_decl
)
327 && (DECL_EXTERNAL (decl
) || decl_replaceable_p (decl
)))
328 return error_mark_node
;
330 /* Variables declared `const' with an initializer are considered
331 to not be overwritable with different initializer by default.
333 ??? Previously we behaved so for scalar variables but not for array
335 return DECL_INITIAL (real_decl
);
338 /* Add the variable DECL to the varpool.
339 Unlike varpool_finalize_decl function is intended to be used
340 by middle end and allows insertion of new variable at arbitrary point
343 varpool_add_new_variable (tree decl
)
346 varpool_finalize_decl (decl
);
347 node
= varpool_node_for_decl (decl
);
348 varpool_call_variable_insertion_hooks (node
);
349 if (varpool_externally_visible_p (node
))
350 node
->externally_visible
= true;
353 /* Return variable availability. See cgraph.h for description of individual
356 cgraph_variable_initializer_availability (varpool_node
*node
)
358 if (!node
->definition
)
359 return AVAIL_NOT_AVAILABLE
;
360 if (!TREE_PUBLIC (node
->decl
))
361 return AVAIL_AVAILABLE
;
362 if (DECL_IN_CONSTANT_POOL (node
->decl
)
363 || DECL_VIRTUAL_P (node
->decl
))
364 return AVAIL_AVAILABLE
;
365 if (node
->alias
&& node
->weakref
)
367 enum availability avail
;
369 cgraph_variable_initializer_availability
370 (varpool_variable_node (node
, &avail
));
373 /* If the variable can be overwritten, return OVERWRITABLE. Takes
374 care of at least one notable extension - the COMDAT variables
375 used to share template instantiations in C++. */
376 if (decl_replaceable_p (node
->decl
)
377 || DECL_EXTERNAL (node
->decl
))
378 return AVAIL_OVERWRITABLE
;
379 return AVAIL_AVAILABLE
;
383 varpool_analyze_node (varpool_node
*node
)
385 tree decl
= node
->decl
;
387 /* When reading back varpool at LTO time, we re-construct the queue in order
388 to have "needed" list right by inserting all needed nodes into varpool.
389 We however don't want to re-analyze already analyzed nodes. */
392 gcc_assert (!in_lto_p
|| cgraph_function_flags_ready
);
393 /* Compute the alignment early so function body expanders are
394 already informed about increased alignment. */
395 align_variable (decl
, 0);
399 (node
, varpool_get_node (node
->alias_target
));
400 else if (DECL_INITIAL (decl
))
401 record_references_in_initializer (decl
, node
->analyzed
);
402 node
->analyzed
= true;
405 /* Assemble thunks and aliases associated to NODE. */
408 assemble_aliases (varpool_node
*node
)
412 for (i
= 0; ipa_ref_list_referring_iterate (&node
->ref_list
, i
, ref
); i
++)
413 if (ref
->use
== IPA_REF_ALIAS
)
415 varpool_node
*alias
= ipa_ref_referring_varpool_node (ref
);
416 do_assemble_alias (alias
->decl
,
417 DECL_ASSEMBLER_NAME (node
->decl
));
418 assemble_aliases (alias
);
422 /* Output one variable, if necessary. Return whether we output it. */
425 varpool_assemble_decl (varpool_node
*node
)
427 tree decl
= node
->decl
;
429 /* Aliases are outout when their target is produced or by
434 /* Constant pool is output from RTL land when the reference
435 survive till this level. */
436 if (DECL_IN_CONSTANT_POOL (decl
) && TREE_ASM_WRITTEN (decl
))
439 /* Decls with VALUE_EXPR should not be in the varpool at all. They
440 are not real variables, but just info for debugging and codegen.
441 Unfortunately at the moment emutls is not updating varpool correctly
442 after turning real vars into value_expr vars. */
443 if (DECL_HAS_VALUE_EXPR_P (decl
)
444 && !targetm
.have_tls
)
447 /* Hard register vars do not need to be output. */
448 if (DECL_HARD_REGISTER (decl
))
451 gcc_checking_assert (!TREE_ASM_WRITTEN (decl
)
452 && TREE_CODE (decl
) == VAR_DECL
453 && !DECL_HAS_VALUE_EXPR_P (decl
));
455 if (!node
->in_other_partition
456 && !DECL_EXTERNAL (decl
))
458 assemble_variable (decl
, 0, 1, 0);
459 gcc_assert (TREE_ASM_WRITTEN (decl
));
460 node
->definition
= true;
461 assemble_aliases (node
);
468 /* Add NODE to queue starting at FIRST.
469 The queue is linked via AUX pointers and terminated by pointer to 1. */
472 enqueue_node (varpool_node
*node
, varpool_node
**first
)
476 gcc_checking_assert (*first
);
481 /* Optimization of function bodies might've rendered some variables as
482 unnecessary so we want to avoid these from being compiled. Re-do
483 reachability starting from variables that are either externally visible
484 or was referred from the asm output routines. */
487 varpool_remove_unreferenced_decls (void)
489 varpool_node
*next
, *node
;
490 varpool_node
*first
= (varpool_node
*)(void *)1;
493 struct pointer_set_t
*referenced
= pointer_set_create ();
498 if (cgraph_dump_file
)
499 fprintf (cgraph_dump_file
, "Trivially needed variables:");
500 FOR_EACH_DEFINED_VARIABLE (node
)
503 && (!varpool_can_remove_if_no_refs (node
)
504 /* We just expanded all function bodies. See if any of
505 them needed the variable. */
506 || DECL_RTL_SET_P (node
->decl
)))
508 enqueue_node (node
, &first
);
509 if (cgraph_dump_file
)
510 fprintf (cgraph_dump_file
, " %s", node
->asm_name ());
513 while (first
!= (varpool_node
*)(void *)1)
516 first
= (varpool_node
*)first
->aux
;
518 if (node
->same_comdat_group
)
521 for (next
= node
->same_comdat_group
;
523 next
= next
->same_comdat_group
)
525 varpool_node
*vnext
= dyn_cast
<varpool_node
*> (next
);
526 if (vnext
&& vnext
->analyzed
&& !symtab_comdat_local_p (next
))
527 enqueue_node (vnext
, &first
);
530 for (i
= 0; ipa_ref_list_reference_iterate (&node
->ref_list
, i
, ref
); i
++)
532 varpool_node
*vnode
= dyn_cast
<varpool_node
*> (ref
->referred
);
534 && !vnode
->in_other_partition
535 && (!DECL_EXTERNAL (ref
->referred
->decl
)
538 enqueue_node (vnode
, &first
);
540 pointer_set_insert (referenced
, node
);
543 if (cgraph_dump_file
)
544 fprintf (cgraph_dump_file
, "\nRemoving variables:");
545 for (node
= varpool_first_defined_variable (); node
; node
= next
)
547 next
= varpool_next_defined_variable (node
);
550 if (cgraph_dump_file
)
551 fprintf (cgraph_dump_file
, " %s", node
->asm_name ());
552 if (pointer_set_contains (referenced
, node
))
553 varpool_remove_initializer (node
);
555 varpool_remove_node (node
);
558 pointer_set_destroy (referenced
);
559 if (cgraph_dump_file
)
560 fprintf (cgraph_dump_file
, "\n");
563 /* For variables in named sections make sure get_variable_section
564 is called before we switch to those sections. Then section
565 conflicts between read-only and read-only requiring relocations
566 sections can be resolved. */
568 varpool_finalize_named_section_flags (varpool_node
*node
)
570 if (!TREE_ASM_WRITTEN (node
->decl
)
572 && !node
->in_other_partition
573 && !DECL_EXTERNAL (node
->decl
)
574 && TREE_CODE (node
->decl
) == VAR_DECL
575 && !DECL_HAS_VALUE_EXPR_P (node
->decl
)
576 && DECL_SECTION_NAME (node
->decl
))
577 get_variable_section (node
->decl
, false);
580 /* Output all variables enqueued to be assembled. */
582 varpool_output_variables (void)
584 bool changed
= false;
590 varpool_remove_unreferenced_decls ();
592 timevar_push (TV_VAROUT
);
594 FOR_EACH_DEFINED_VARIABLE (node
)
595 varpool_finalize_named_section_flags (node
);
597 FOR_EACH_DEFINED_VARIABLE (node
)
598 if (varpool_assemble_decl (node
))
600 timevar_pop (TV_VAROUT
);
604 /* Create a new global variable of type TYPE. */
606 add_new_static_var (tree type
)
609 varpool_node
*new_node
;
611 new_decl
= create_tmp_var_raw (type
, NULL
);
612 DECL_NAME (new_decl
) = create_tmp_var_name (NULL
);
613 TREE_READONLY (new_decl
) = 0;
614 TREE_STATIC (new_decl
) = 1;
615 TREE_USED (new_decl
) = 1;
616 DECL_CONTEXT (new_decl
) = NULL_TREE
;
617 DECL_ABSTRACT (new_decl
) = 0;
618 lang_hooks
.dup_lang_specific_decl (new_decl
);
619 new_node
= varpool_node_for_decl (new_decl
);
620 varpool_finalize_decl (new_decl
);
622 return new_node
->decl
;
625 /* Attempt to mark ALIAS as an alias to DECL. Return TRUE if successful.
626 Extra name aliases are output whenever DECL is output. */
629 varpool_create_variable_alias (tree alias
, tree decl
)
631 varpool_node
*alias_node
;
633 gcc_assert (TREE_CODE (decl
) == VAR_DECL
);
634 gcc_assert (TREE_CODE (alias
) == VAR_DECL
);
635 alias_node
= varpool_node_for_decl (alias
);
636 alias_node
->alias
= true;
637 alias_node
->definition
= true;
638 alias_node
->alias_target
= decl
;
639 if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias
)) != NULL
)
640 alias_node
->weakref
= true;
644 /* Attempt to mark ALIAS as an alias to DECL. Return TRUE if successful.
645 Extra name aliases are output whenever DECL is output. */
648 varpool_extra_name_alias (tree alias
, tree decl
)
650 varpool_node
*alias_node
;
652 #ifndef ASM_OUTPUT_DEF
653 /* If aliases aren't supported by the assembler, fail. */
656 alias_node
= varpool_create_variable_alias (alias
, decl
);
657 alias_node
->cpp_implicit_alias
= true;
659 /* Extra name alias mechanizm creates aliases really late
660 via DECL_ASSEMBLER_NAME mechanizm.
661 This is unfortunate because they are not going through the
662 standard channels. Ensure they get output. */
663 if (cpp_implicit_aliases_done
)
664 symtab_resolve_alias (alias_node
,
665 varpool_node_for_decl (decl
));
669 /* Call calback on NODE and aliases associated to NODE.
670 When INCLUDE_OVERWRITABLE is false, overwritable aliases and thunks are
674 varpool_for_node_and_aliases (varpool_node
*node
,
675 bool (*callback
) (varpool_node
*, void *),
677 bool include_overwritable
)
682 if (callback (node
, data
))
684 for (i
= 0; ipa_ref_list_referring_iterate (&node
->ref_list
, i
, ref
); i
++)
685 if (ref
->use
== IPA_REF_ALIAS
)
687 varpool_node
*alias
= ipa_ref_referring_varpool_node (ref
);
688 if (include_overwritable
689 || cgraph_variable_initializer_availability (alias
) > AVAIL_OVERWRITABLE
)
690 if (varpool_for_node_and_aliases (alias
, callback
, data
,
691 include_overwritable
))