0908b6a02eb76511823840ccbb7ae4abaa51ccc5
[gcc.git] / gcc / cgraph.c
1 /* Callgraph handling code.
2 Copyright (C) 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Jan Hubicka
4
5 This file is part of GCC.
6
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 2, or (at your option) any later
10 version.
11
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
15 for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA. */
21
22 /* This file contains basic routines manipulating call graph and variable pool
23
24 The callgraph:
25
26 The call-graph is data structure designed for intra-procedural optimization
27 but it is also used in non-unit-at-a-time compilation to allow easier code
28 sharing.
29
30 The call-graph consist of nodes and edges represented via linked lists.
31 Each function (external or not) corresponds to the unique node (in
32 contrast to tree DECL nodes where we can have multiple nodes for each
33 function).
34
35 The mapping from declarations to call-graph nodes is done using hash table
36 based on DECL_ASSEMBLER_NAME, so it is essential for assembler name to
37 not change once the declaration is inserted into the call-graph.
38 The call-graph nodes are created lazily using cgraph_node function when
39 called for unknown declaration.
40
41 When built, there is one edge for each direct call. It is possible that
42 the reference will be later optimized out. The call-graph is built
43 conservatively in order to make conservative data flow analysis possible.
44
45 The callgraph at the moment does not represent indirect calls or calls
46 from other compilation unit. Flag NEEDED is set for each node that may
47 be accessed in such a invisible way and it shall be considered an
48 entry point to the callgraph.
49
50 Intraprocedural information:
51
52 Callgraph is place to store data needed for intraprocedural optimization.
53 All data structures are divided into three components: local_info that
54 is produced while analyzing the function, global_info that is result
55 of global walking of the callgraph on the end of compilation and
56 rtl_info used by RTL backend to propagate data from already compiled
57 functions to their callers.
58
59 Inlining plans:
60
61 The function inlining information is decided in advance and maintained
62 in the callgraph as so called inline plan.
63 For each inlined call, the callee's node is cloned to represent the
64 new function copy produced by inliner.
65 Each inlined call gets a unique corresponding clone node of the callee
66 and the data structure is updated while inlining is performed, so
67 the clones are eliminated and their callee edges redirected to the
68 caller.
69
70 Each edge has "inline_failed" field. When the field is set to NULL,
71 the call will be inlined. When it is non-NULL it contains a reason
72 why inlining wasn't performed.
73
74
75 The varpool data structure:
76
77 Varpool is used to maintain variables in similar manner as call-graph
78 is used for functions. Most of the API is symmetric replacing cgraph
79 function prefix by cgraph_varpool */
80
81
82 #include "config.h"
83 #include "system.h"
84 #include "coretypes.h"
85 #include "tm.h"
86 #include "tree.h"
87 #include "langhooks.h"
88 #include "hashtab.h"
89 #include "toplev.h"
90 #include "flags.h"
91 #include "ggc.h"
92 #include "debug.h"
93 #include "target.h"
94 #include "cgraph.h"
95 #include "varray.h"
96 #include "output.h"
97 #include "intl.h"
98
99 /* Hash table used to convert declarations into nodes. */
100 static GTY((param_is (struct cgraph_node))) htab_t cgraph_hash;
101
102 /* The linked list of cgraph nodes. */
103 struct cgraph_node *cgraph_nodes;
104
105 /* Queue of cgraph nodes scheduled to be lowered. */
106 struct cgraph_node *cgraph_nodes_queue;
107
108 /* Number of nodes in existence. */
109 int cgraph_n_nodes;
110
111 /* Maximal uid used in cgraph nodes. */
112 int cgraph_max_uid;
113
114 /* Set when whole unit has been analyzed so we can access global info. */
115 bool cgraph_global_info_ready = false;
116
117 /* Hash table used to convert declarations into nodes. */
118 static GTY((param_is (struct cgraph_varpool_node))) htab_t cgraph_varpool_hash;
119
120 /* Queue of cgraph nodes scheduled to be lowered and output. */
121 struct cgraph_varpool_node *cgraph_varpool_nodes_queue;
122
123 /* Number of nodes in existence. */
124 int cgraph_varpool_n_nodes;
125
126 /* The linked list of cgraph varpool nodes. */
127 static GTY(()) struct cgraph_varpool_node *cgraph_varpool_nodes;
128
129 static hashval_t hash_node (const void *);
130 static int eq_node (const void *, const void *);
131
132 /* Returns a hash code for P. */
133
134 static hashval_t
135 hash_node (const void *p)
136 {
137 const struct cgraph_node *n = p;
138 return (hashval_t) DECL_UID (n->decl);
139 }
140
141 /* Returns nonzero if P1 and P2 are equal. */
142
143 static int
144 eq_node (const void *p1, const void *p2)
145 {
146 const struct cgraph_node *n1 = p1, *n2 = p2;
147 return DECL_UID (n1->decl) == DECL_UID (n2->decl);
148 }
149
150 /* Allocate new callgraph node and insert it into basic data structures. */
151 static struct cgraph_node *
152 cgraph_create_node (void)
153 {
154 struct cgraph_node *node;
155
156 node = ggc_alloc_cleared (sizeof (*node));
157 node->next = cgraph_nodes;
158 node->uid = cgraph_max_uid++;
159 if (cgraph_nodes)
160 cgraph_nodes->previous = node;
161 node->previous = NULL;
162 cgraph_nodes = node;
163 cgraph_n_nodes++;
164 return node;
165 }
166
167 /* Return cgraph node assigned to DECL. Create new one when needed. */
168 struct cgraph_node *
169 cgraph_node (tree decl)
170 {
171 struct cgraph_node key, *node, **slot;
172
173 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
174
175 if (!cgraph_hash)
176 cgraph_hash = htab_create_ggc (10, hash_node, eq_node, NULL);
177
178 key.decl = decl;
179
180 slot = (struct cgraph_node **) htab_find_slot (cgraph_hash, &key, INSERT);
181
182 if (*slot)
183 return *slot;
184
185 node = cgraph_create_node ();
186 node->decl = decl;
187 *slot = node;
188 if (DECL_CONTEXT (decl) && TREE_CODE (DECL_CONTEXT (decl)) == FUNCTION_DECL)
189 {
190 node->origin = cgraph_node (DECL_CONTEXT (decl));
191 node->next_nested = node->origin->nested;
192 node->origin->nested = node;
193 }
194 return node;
195 }
196
197 /* Return callgraph edge representing CALL_EXPR. */
198 struct cgraph_edge *
199 cgraph_edge (struct cgraph_node *node, tree call_expr)
200 {
201 struct cgraph_edge *e;
202
203 /* This loop may turn out to be performance problem. In such case adding
204 hashtables into call nodes with very many edges is probably best
205 solution. It is not good idea to add pointer into CALL_EXPR itself
206 because we want to make possible having multiple cgraph nodes representing
207 different clones of the same body before the body is actually cloned. */
208 for (e = node->callees; e; e= e->next_callee)
209 if (e->call_expr == call_expr)
210 break;
211 return e;
212 }
213
214 /* Create edge from CALLER to CALLEE in the cgraph. */
215
216 struct cgraph_edge *
217 cgraph_create_edge (struct cgraph_node *caller, struct cgraph_node *callee,
218 tree call_expr)
219 {
220 struct cgraph_edge *edge = ggc_alloc (sizeof (struct cgraph_edge));
221 #ifdef ENABLE_CHECKING
222 struct cgraph_edge *e;
223
224 for (e = caller->callees; e; e = e->next_callee)
225 gcc_assert (e->call_expr != call_expr);
226 #endif
227
228 gcc_assert (TREE_CODE (call_expr) == CALL_EXPR);
229
230 if (!DECL_SAVED_TREE (callee->decl))
231 edge->inline_failed = N_("function body not available");
232 else if (callee->local.redefined_extern_inline)
233 edge->inline_failed = N_("redefined extern inline functions are not "
234 "considered for inlining");
235 else if (callee->local.inlinable)
236 edge->inline_failed = N_("function not considered for inlining");
237 else
238 edge->inline_failed = N_("function not inlinable");
239
240 edge->aux = NULL;
241
242 edge->caller = caller;
243 edge->callee = callee;
244 edge->call_expr = call_expr;
245 edge->next_caller = callee->callers;
246 edge->next_callee = caller->callees;
247 caller->callees = edge;
248 callee->callers = edge;
249 return edge;
250 }
251
252 /* Remove the edge E the cgraph. */
253
254 void
255 cgraph_remove_edge (struct cgraph_edge *e)
256 {
257 struct cgraph_edge **edge, **edge2;
258
259 for (edge = &e->callee->callers; *edge && *edge != e;
260 edge = &((*edge)->next_caller))
261 continue;
262 gcc_assert (*edge);
263 *edge = (*edge)->next_caller;
264 for (edge2 = &e->caller->callees; *edge2 && *edge2 != e;
265 edge2 = &(*edge2)->next_callee)
266 continue;
267 gcc_assert (*edge2);
268 *edge2 = (*edge2)->next_callee;
269 }
270
271 /* Redirect callee of E to N. The function does not update underlying
272 call expression. */
273
274 void
275 cgraph_redirect_edge_callee (struct cgraph_edge *e, struct cgraph_node *n)
276 {
277 struct cgraph_edge **edge;
278
279 for (edge = &e->callee->callers; *edge && *edge != e;
280 edge = &((*edge)->next_caller))
281 continue;
282 gcc_assert (*edge);
283 *edge = (*edge)->next_caller;
284 e->callee = n;
285 e->next_caller = n->callers;
286 n->callers = e;
287 }
288
289 /* Remove the node from cgraph. */
290
291 void
292 cgraph_remove_node (struct cgraph_node *node)
293 {
294 void **slot;
295 bool check_dead = 1;
296
297 while (node->callers)
298 cgraph_remove_edge (node->callers);
299 while (node->callees)
300 cgraph_remove_edge (node->callees);
301 while (node->nested)
302 cgraph_remove_node (node->nested);
303 if (node->origin)
304 {
305 struct cgraph_node **node2 = &node->origin->nested;
306
307 while (*node2 != node)
308 node2 = &(*node2)->next_nested;
309 *node2 = node->next_nested;
310 }
311 if (node->previous)
312 node->previous->next = node->next;
313 else
314 cgraph_nodes = node->next;
315 if (node->next)
316 node->next->previous = node->previous;
317 slot = htab_find_slot (cgraph_hash, node, NO_INSERT);
318 if (*slot == node)
319 {
320 if (node->next_clone)
321 *slot = node->next_clone;
322 else
323 {
324 htab_clear_slot (cgraph_hash, slot);
325 if (!dump_enabled_p (TDI_tree_all))
326 {
327 DECL_SAVED_TREE (node->decl) = NULL;
328 DECL_STRUCT_FUNCTION (node->decl) = NULL;
329 }
330 check_dead = false;
331 }
332 }
333 else
334 {
335 struct cgraph_node *n;
336
337 for (n = *slot; n->next_clone != node; n = n->next_clone)
338 continue;
339 n->next_clone = node->next_clone;
340 }
341
342 /* Work out whether we still need a function body (either there is inline
343 clone or there is out of line function whose body is not written). */
344 if (check_dead && flag_unit_at_a_time)
345 {
346 struct cgraph_node *n;
347
348 for (n = *slot; n; n = n->next_clone)
349 if (n->global.inlined_to
350 || (!n->global.inlined_to
351 && !TREE_ASM_WRITTEN (n->decl) && !DECL_EXTERNAL (n->decl)))
352 break;
353 if (!n && !dump_enabled_p (TDI_tree_all))
354 {
355 DECL_SAVED_TREE (node->decl) = NULL;
356 DECL_STRUCT_FUNCTION (node->decl) = NULL;
357 DECL_INITIAL (node->decl) = error_mark_node;
358 }
359 }
360 cgraph_n_nodes--;
361 /* Do not free the structure itself so the walk over chain can continue. */
362 }
363
364 /* Notify finalize_compilation_unit that given node is reachable. */
365
366 void
367 cgraph_mark_reachable_node (struct cgraph_node *node)
368 {
369 if (!node->reachable && node->local.finalized)
370 {
371 notice_global_symbol (node->decl);
372 node->reachable = 1;
373
374 node->next_needed = cgraph_nodes_queue;
375 cgraph_nodes_queue = node;
376 }
377 }
378
379 /* Likewise indicate that a node is needed, i.e. reachable via some
380 external means. */
381
382 void
383 cgraph_mark_needed_node (struct cgraph_node *node)
384 {
385 node->needed = 1;
386 cgraph_mark_reachable_node (node);
387 }
388
389 /* Return local info for the compiled function. */
390
391 struct cgraph_local_info *
392 cgraph_local_info (tree decl)
393 {
394 struct cgraph_node *node;
395
396 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
397 node = cgraph_node (decl);
398 return &node->local;
399 }
400
401 /* Return local info for the compiled function. */
402
403 struct cgraph_global_info *
404 cgraph_global_info (tree decl)
405 {
406 struct cgraph_node *node;
407
408 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL && cgraph_global_info_ready);
409 node = cgraph_node (decl);
410 return &node->global;
411 }
412
413 /* Return local info for the compiled function. */
414
415 struct cgraph_rtl_info *
416 cgraph_rtl_info (tree decl)
417 {
418 struct cgraph_node *node;
419
420 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
421 node = cgraph_node (decl);
422 if (decl != current_function_decl
423 && !TREE_ASM_WRITTEN (node->decl))
424 return NULL;
425 return &node->rtl;
426 }
427
428 /* Return name of the node used in debug output. */
429 const char *
430 cgraph_node_name (struct cgraph_node *node)
431 {
432 return lang_hooks.decl_printable_name (node->decl, 2);
433 }
434
435 /* Dump given cgraph node. */
436 void
437 dump_cgraph_node (FILE *f, struct cgraph_node *node)
438 {
439 struct cgraph_edge *edge;
440 fprintf (f, "%s/%i:", cgraph_node_name (node), node->uid);
441 if (node->global.inlined_to)
442 fprintf (f, " (inline copy in %s/%i)",
443 cgraph_node_name (node->global.inlined_to),
444 node->global.inlined_to->uid);
445 if (node->local.self_insns)
446 fprintf (f, " %i insns", node->local.self_insns);
447 if (node->global.insns && node->global.insns != node->local.self_insns)
448 fprintf (f, " (%i after inlining)", node->global.insns);
449 if (node->origin)
450 fprintf (f, " nested in: %s", cgraph_node_name (node->origin));
451 if (node->needed)
452 fprintf (f, " needed");
453 else if (node->reachable)
454 fprintf (f, " reachable");
455 if (DECL_SAVED_TREE (node->decl))
456 fprintf (f, " tree");
457 if (node->output)
458 fprintf (f, " output");
459 if (node->local.local)
460 fprintf (f, " local");
461 if (node->local.disregard_inline_limits)
462 fprintf (f, " always_inline");
463 else if (node->local.inlinable)
464 fprintf (f, " inlinable");
465 if (TREE_ASM_WRITTEN (node->decl))
466 fprintf (f, " asm_written");
467
468 fprintf (f, "\n called by: ");
469 for (edge = node->callers; edge; edge = edge->next_caller)
470 {
471 fprintf (f, "%s/%i ", cgraph_node_name (edge->caller),
472 edge->caller->uid);
473 if (!edge->inline_failed)
474 fprintf(f, "(inlined) ");
475 }
476
477 fprintf (f, "\n calls: ");
478 for (edge = node->callees; edge; edge = edge->next_callee)
479 {
480 fprintf (f, "%s/%i ", cgraph_node_name (edge->callee),
481 edge->callee->uid);
482 if (!edge->inline_failed)
483 fprintf(f, "(inlined) ");
484 }
485 fprintf (f, "\n");
486 }
487
488 /* Dump the callgraph. */
489
490 void
491 dump_cgraph (FILE *f)
492 {
493 struct cgraph_node *node;
494
495 fprintf (f, "callgraph:\n\n");
496 for (node = cgraph_nodes; node; node = node->next)
497 dump_cgraph_node (f, node);
498 }
499
500 /* Returns a hash code for P. */
501
502 static hashval_t
503 hash_varpool_node (const void *p)
504 {
505 const struct cgraph_varpool_node *n = p;
506 return (hashval_t) DECL_UID (n->decl);
507 }
508
509 /* Returns nonzero if P1 and P2 are equal. */
510
511 static int
512 eq_varpool_node (const void *p1, const void *p2)
513 {
514 const struct cgraph_varpool_node *n1 = p1, *n2 = p2;
515 return DECL_UID (n1->decl) == DECL_UID (n2->decl);
516 }
517
518 /* Return cgraph_varpool node assigned to DECL. Create new one when needed. */
519 struct cgraph_varpool_node *
520 cgraph_varpool_node (tree decl)
521 {
522 struct cgraph_varpool_node key, *node, **slot;
523
524 gcc_assert (DECL_P (decl) && TREE_CODE (decl) != FUNCTION_DECL);
525
526 if (!cgraph_varpool_hash)
527 cgraph_varpool_hash = htab_create_ggc (10, hash_varpool_node,
528 eq_varpool_node, NULL);
529 key.decl = decl;
530 slot = (struct cgraph_varpool_node **)
531 htab_find_slot (cgraph_varpool_hash, &key, INSERT);
532 if (*slot)
533 return *slot;
534 node = ggc_alloc_cleared (sizeof (*node));
535 node->decl = decl;
536 cgraph_varpool_n_nodes++;
537 cgraph_varpool_nodes = node;
538 *slot = node;
539 return node;
540 }
541
542 /* Set the DECL_ASSEMBLER_NAME and update cgraph hashtables. */
543 void
544 change_decl_assembler_name (tree decl, tree name)
545 {
546 if (!DECL_ASSEMBLER_NAME_SET_P (decl))
547 {
548 SET_DECL_ASSEMBLER_NAME (decl, name);
549 return;
550 }
551 if (name == DECL_ASSEMBLER_NAME (decl))
552 return;
553
554 if (TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))
555 && DECL_RTL_SET_P (decl))
556 warning ("%D renamed after being referenced in assembly", decl);
557
558 SET_DECL_ASSEMBLER_NAME (decl, name);
559 }
560
561 /* Notify finalize_compilation_unit that given node is reachable
562 or needed. */
563 void
564 cgraph_varpool_mark_needed_node (struct cgraph_varpool_node *node)
565 {
566 if (!node->needed && node->finalized)
567 {
568 node->next_needed = cgraph_varpool_nodes_queue;
569 cgraph_varpool_nodes_queue = node;
570 notice_global_symbol (node->decl);
571 }
572 node->needed = 1;
573 }
574
575 void
576 cgraph_varpool_finalize_decl (tree decl)
577 {
578 struct cgraph_varpool_node *node = cgraph_varpool_node (decl);
579
580 /* The first declaration of a variable that comes through this function
581 decides whether it is global (in C, has external linkage)
582 or local (in C, has internal linkage). So do nothing more
583 if this function has already run. */
584 if (node->finalized)
585 return;
586 if (node->needed)
587 {
588 node->next_needed = cgraph_varpool_nodes_queue;
589 cgraph_varpool_nodes_queue = node;
590 notice_global_symbol (decl);
591 }
592 node->finalized = true;
593
594 if (/* Externally visible variables must be output. The exception are
595 COMDAT functions that must be output only when they are needed. */
596 (TREE_PUBLIC (decl) && !DECL_COMDAT (decl))
597 /* Function whose name is output to the assembler file must be produced.
598 It is possible to assemble the name later after finalizing the function
599 and the fact is noticed in assemble_name then. */
600 || (DECL_ASSEMBLER_NAME_SET_P (decl)
601 && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
602 {
603 cgraph_varpool_mark_needed_node (node);
604 }
605 }
606
607 bool
608 cgraph_varpool_assemble_pending_decls (void)
609 {
610 bool changed = false;
611
612 while (cgraph_varpool_nodes_queue)
613 {
614 tree decl = cgraph_varpool_nodes_queue->decl;
615 struct cgraph_varpool_node *node = cgraph_varpool_nodes_queue;
616
617 cgraph_varpool_nodes_queue = cgraph_varpool_nodes_queue->next_needed;
618 if (!TREE_ASM_WRITTEN (decl))
619 {
620 assemble_variable (decl, 0, 1, 0);
621 changed = true;
622 }
623 node->next_needed = NULL;
624 }
625 return changed;
626 }
627
628 /* Return true when the DECL can possibly be inlined. */
629 bool
630 cgraph_function_possibly_inlined_p (tree decl)
631 {
632 if (!cgraph_global_info_ready)
633 return (DECL_INLINE (decl) && !flag_really_no_inline);
634 return DECL_POSSIBLY_INLINED (decl);
635 }
636
637 /* Create clone of E in the node N represented by CALL_EXPR the callgraph. */
638 struct cgraph_edge *
639 cgraph_clone_edge (struct cgraph_edge *e, struct cgraph_node *n, tree call_expr)
640 {
641 struct cgraph_edge *new = cgraph_create_edge (n, e->callee, call_expr);
642
643 new->inline_failed = e->inline_failed;
644 return new;
645 }
646
647 /* Create node representing clone of N. */
648 struct cgraph_node *
649 cgraph_clone_node (struct cgraph_node *n)
650 {
651 struct cgraph_node *new = cgraph_create_node ();
652 struct cgraph_edge *e;
653
654 new->decl = n->decl;
655 new->origin = n->origin;
656 if (new->origin)
657 {
658 new->next_nested = new->origin->nested;
659 new->origin->nested = new;
660 }
661 new->analyzed = n->analyzed;
662 new->local = n->local;
663 new->global = n->global;
664 new->rtl = n->rtl;
665
666 for (e = n->callees;e; e=e->next_callee)
667 cgraph_clone_edge (e, new, e->call_expr);
668
669 new->next_clone = n->next_clone;
670 n->next_clone = new;
671
672 return new;
673 }
674
675 /* NODE is no longer nested function; update cgraph accordingly. */
676 void
677 cgraph_unnest_node (struct cgraph_node *node)
678 {
679 struct cgraph_node **node2 = &node->origin->nested;
680 gcc_assert (node->origin);
681
682 while (*node2 != node)
683 node2 = &(*node2)->next_nested;
684 *node2 = node->next_nested;
685 node->origin = NULL;
686 }
687 #include "gt-cgraph.h"