2004-10-25 Benjamin Kosnik <bkoz@redhat.com>
[official-gcc.git] / gcc / cgraph.c
blob7206251ac547e765a9de57e8e6e205855ae5e514
1 /* Callgraph handling code.
2 Copyright (C) 2003, 2004 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 2, or (at your option) any later
10 version.
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.
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. */
22 /* This file contains basic routines manipulating call graph and variable pool
24 The callgraph:
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.
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).
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.
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.
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.
50 Intraprocedural information:
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.
59 Inlining plans:
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.
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.
75 The varpool data structure:
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 */
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"
99 /* Hash table used to convert declarations into nodes. */
100 static GTY((param_is (struct cgraph_node))) htab_t cgraph_hash;
102 /* The linked list of cgraph nodes. */
103 struct cgraph_node *cgraph_nodes;
105 /* Queue of cgraph nodes scheduled to be lowered. */
106 struct cgraph_node *cgraph_nodes_queue;
108 /* Number of nodes in existence. */
109 int cgraph_n_nodes;
111 /* Maximal uid used in cgraph nodes. */
112 int cgraph_max_uid;
114 /* Set when whole unit has been analyzed so we can access global info. */
115 bool cgraph_global_info_ready = false;
117 /* Hash table used to convert declarations into nodes. */
118 static GTY((param_is (struct cgraph_varpool_node))) htab_t cgraph_varpool_hash;
120 /* Queue of cgraph nodes scheduled to be lowered and output. */
121 struct cgraph_varpool_node *cgraph_varpool_nodes_queue;
123 /* Number of nodes in existence. */
124 int cgraph_varpool_n_nodes;
126 /* The linked list of cgraph varpool nodes. */
127 static GTY(()) struct cgraph_varpool_node *cgraph_varpool_nodes;
129 static hashval_t hash_node (const void *);
130 static int eq_node (const void *, const void *);
132 /* Returns a hash code for P. */
134 static hashval_t
135 hash_node (const void *p)
137 const struct cgraph_node *n = p;
138 return (hashval_t) DECL_UID (n->decl);
141 /* Returns nonzero if P1 and P2 are equal. */
143 static int
144 eq_node (const void *p1, const void *p2)
146 const struct cgraph_node *n1 = p1, *n2 = p2;
147 return DECL_UID (n1->decl) == DECL_UID (n2->decl);
150 /* Allocate new callgraph node and insert it into basic data structures. */
151 static struct cgraph_node *
152 cgraph_create_node (void)
154 struct cgraph_node *node;
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;
167 /* Return cgraph node assigned to DECL. Create new one when needed. */
168 struct cgraph_node *
169 cgraph_node (tree decl)
171 struct cgraph_node key, *node, **slot;
173 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
175 if (!cgraph_hash)
176 cgraph_hash = htab_create_ggc (10, hash_node, eq_node, NULL);
178 key.decl = decl;
180 slot = (struct cgraph_node **) htab_find_slot (cgraph_hash, &key, INSERT);
182 if (*slot)
183 return *slot;
185 node = cgraph_create_node ();
186 node->decl = decl;
187 *slot = node;
188 if (DECL_CONTEXT (decl) && TREE_CODE (DECL_CONTEXT (decl)) == FUNCTION_DECL)
190 node->origin = cgraph_node (DECL_CONTEXT (decl));
191 node->next_nested = node->origin->nested;
192 node->origin->nested = node;
194 return node;
197 /* Return callgraph edge representing CALL_EXPR. */
198 struct cgraph_edge *
199 cgraph_edge (struct cgraph_node *node, tree call_expr)
201 struct cgraph_edge *e;
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;
214 /* Create edge from CALLER to CALLEE in the cgraph. */
216 struct cgraph_edge *
217 cgraph_create_edge (struct cgraph_node *caller, struct cgraph_node *callee,
218 tree call_expr)
220 struct cgraph_edge *edge = ggc_alloc (sizeof (struct cgraph_edge));
221 #ifdef ENABLE_CHECKING
222 struct cgraph_edge *e;
224 for (e = caller->callees; e; e = e->next_callee)
225 gcc_assert (e->call_expr != call_expr);
226 #endif
228 gcc_assert (TREE_CODE (call_expr) == CALL_EXPR);
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");
240 edge->aux = NULL;
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;
252 /* Remove the edge E the cgraph. */
254 void
255 cgraph_remove_edge (struct cgraph_edge *e)
257 struct cgraph_edge **edge, **edge2;
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;
271 /* Redirect callee of E to N. The function does not update underlying
272 call expression. */
274 void
275 cgraph_redirect_edge_callee (struct cgraph_edge *e, struct cgraph_node *n)
277 struct cgraph_edge **edge;
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;
289 /* Remove the node from cgraph. */
291 void
292 cgraph_remove_node (struct cgraph_node *node)
294 void **slot;
295 bool check_dead = 1;
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)
305 struct cgraph_node **node2 = &node->origin->nested;
307 while (*node2 != node)
308 node2 = &(*node2)->next_nested;
309 *node2 = node->next_nested;
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)
320 if (node->next_clone)
321 *slot = node->next_clone;
322 else
324 htab_clear_slot (cgraph_hash, slot);
325 if (!dump_enabled_p (TDI_tree_all))
327 DECL_SAVED_TREE (node->decl) = NULL;
328 DECL_STRUCT_FUNCTION (node->decl) = NULL;
330 check_dead = false;
333 else
335 struct cgraph_node *n;
337 for (n = *slot; n->next_clone != node; n = n->next_clone)
338 continue;
339 n->next_clone = node->next_clone;
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)
346 struct cgraph_node *n;
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))
355 DECL_SAVED_TREE (node->decl) = NULL;
356 DECL_STRUCT_FUNCTION (node->decl) = NULL;
357 DECL_INITIAL (node->decl) = error_mark_node;
360 cgraph_n_nodes--;
361 /* Do not free the structure itself so the walk over chain can continue. */
364 /* Notify finalize_compilation_unit that given node is reachable. */
366 void
367 cgraph_mark_reachable_node (struct cgraph_node *node)
369 if (!node->reachable && node->local.finalized)
371 notice_global_symbol (node->decl);
372 node->reachable = 1;
374 node->next_needed = cgraph_nodes_queue;
375 cgraph_nodes_queue = node;
379 /* Likewise indicate that a node is needed, i.e. reachable via some
380 external means. */
382 void
383 cgraph_mark_needed_node (struct cgraph_node *node)
385 node->needed = 1;
386 cgraph_mark_reachable_node (node);
389 /* Return true when CALLER_DECL calls CALLEE_DECL. */
391 bool
392 cgraph_calls_p (tree caller_decl, tree callee_decl)
394 struct cgraph_node *caller = cgraph_node (caller_decl);
395 struct cgraph_node *callee = cgraph_node (callee_decl);
396 struct cgraph_edge *edge;
398 for (edge = callee->callers; edge && (edge)->caller != caller;
399 edge = (edge->next_caller))
400 continue;
401 return edge != NULL;
404 /* Return local info for the compiled function. */
406 struct cgraph_local_info *
407 cgraph_local_info (tree decl)
409 struct cgraph_node *node;
411 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
412 node = cgraph_node (decl);
413 return &node->local;
416 /* Return local info for the compiled function. */
418 struct cgraph_global_info *
419 cgraph_global_info (tree decl)
421 struct cgraph_node *node;
423 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL && cgraph_global_info_ready);
424 node = cgraph_node (decl);
425 return &node->global;
428 /* Return local info for the compiled function. */
430 struct cgraph_rtl_info *
431 cgraph_rtl_info (tree decl)
433 struct cgraph_node *node;
435 gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
436 node = cgraph_node (decl);
437 if (decl != current_function_decl
438 && !TREE_ASM_WRITTEN (node->decl))
439 return NULL;
440 return &node->rtl;
443 /* Return name of the node used in debug output. */
444 const char *
445 cgraph_node_name (struct cgraph_node *node)
447 return lang_hooks.decl_printable_name (node->decl, 2);
450 /* Dump given cgraph node. */
451 void
452 dump_cgraph_node (FILE *f, struct cgraph_node *node)
454 struct cgraph_edge *edge;
455 fprintf (f, "%s/%i:", cgraph_node_name (node), node->uid);
456 if (node->global.inlined_to)
457 fprintf (f, " (inline copy in %s/%i)",
458 cgraph_node_name (node->global.inlined_to),
459 node->global.inlined_to->uid);
460 if (node->local.self_insns)
461 fprintf (f, " %i insns", node->local.self_insns);
462 if (node->global.insns && node->global.insns != node->local.self_insns)
463 fprintf (f, " (%i after inlining)", node->global.insns);
464 if (node->origin)
465 fprintf (f, " nested in: %s", cgraph_node_name (node->origin));
466 if (node->needed)
467 fprintf (f, " needed");
468 else if (node->reachable)
469 fprintf (f, " reachable");
470 if (DECL_SAVED_TREE (node->decl))
471 fprintf (f, " tree");
472 if (node->output)
473 fprintf (f, " output");
475 if (node->local.local)
476 fprintf (f, " local");
477 if (node->local.external)
478 fprintf (f, " external");
479 if (node->local.calls_read_all)
480 fprintf (f, " calls_read_all");
481 if (node->local.calls_write_all)
482 fprintf (f, " calls_write_all");
483 if (node->local.disregard_inline_limits)
484 fprintf (f, " always_inline");
485 else if (node->local.inlinable)
486 fprintf (f, " inlinable");
487 if (TREE_ASM_WRITTEN (node->decl))
488 fprintf (f, " asm_written");
490 fprintf (f, "\n called by: ");
491 for (edge = node->callers; edge; edge = edge->next_caller)
493 fprintf (f, "%s/%i ", cgraph_node_name (edge->caller),
494 edge->caller->uid);
495 if (!edge->inline_failed)
496 fprintf(f, "(inlined) ");
499 fprintf (f, "\n calls: ");
500 for (edge = node->callees; edge; edge = edge->next_callee)
502 fprintf (f, "%s/%i ", cgraph_node_name (edge->callee),
503 edge->callee->uid);
504 if (!edge->inline_failed)
505 fprintf(f, "(inlined) ");
507 fprintf (f, "\n");
510 /* Dump the callgraph. */
512 void
513 dump_cgraph (FILE *f)
515 struct cgraph_node *node;
517 fprintf (f, "callgraph:\n\n");
518 for (node = cgraph_nodes; node; node = node->next)
519 dump_cgraph_node (f, node);
522 /* Returns a hash code for P. */
524 static hashval_t
525 hash_varpool_node (const void *p)
527 const struct cgraph_varpool_node *n = p;
528 return (hashval_t) DECL_UID (n->decl);
531 /* Returns nonzero if P1 and P2 are equal. */
533 static int
534 eq_varpool_node (const void *p1, const void *p2)
536 const struct cgraph_varpool_node *n1 = p1, *n2 = p2;
537 return DECL_UID (n1->decl) == DECL_UID (n2->decl);
540 /* Return cgraph_varpool node assigned to DECL. Create new one when needed. */
541 struct cgraph_varpool_node *
542 cgraph_varpool_node (tree decl)
544 struct cgraph_varpool_node key, *node, **slot;
546 gcc_assert (DECL_P (decl) && TREE_CODE (decl) != FUNCTION_DECL);
548 if (!cgraph_varpool_hash)
549 cgraph_varpool_hash = htab_create_ggc (10, hash_varpool_node,
550 eq_varpool_node, NULL);
551 key.decl = decl;
552 slot = (struct cgraph_varpool_node **)
553 htab_find_slot (cgraph_varpool_hash, &key, INSERT);
554 if (*slot)
555 return *slot;
556 node = ggc_alloc_cleared (sizeof (*node));
557 node->decl = decl;
558 cgraph_varpool_n_nodes++;
559 cgraph_varpool_nodes = node;
560 *slot = node;
561 return node;
564 /* Set the DECL_ASSEMBLER_NAME and update cgraph hashtables. */
565 void
566 change_decl_assembler_name (tree decl, tree name)
568 if (!DECL_ASSEMBLER_NAME_SET_P (decl))
570 SET_DECL_ASSEMBLER_NAME (decl, name);
571 return;
573 if (name == DECL_ASSEMBLER_NAME (decl))
574 return;
576 if (TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))
577 && DECL_RTL_SET_P (decl))
578 warning ("%D renamed after being referenced in assembly", decl);
580 SET_DECL_ASSEMBLER_NAME (decl, name);
583 /* Notify finalize_compilation_unit that given node is reachable
584 or needed. */
585 void
586 cgraph_varpool_mark_needed_node (struct cgraph_varpool_node *node)
588 if (!node->needed && node->finalized)
590 node->next_needed = cgraph_varpool_nodes_queue;
591 cgraph_varpool_nodes_queue = node;
592 notice_global_symbol (node->decl);
594 node->needed = 1;
597 void
598 cgraph_varpool_finalize_decl (tree decl)
600 struct cgraph_varpool_node *node = cgraph_varpool_node (decl);
602 /* The first declaration of a variable that comes through this function
603 decides whether it is global (in C, has external linkage)
604 or local (in C, has internal linkage). So do nothing more
605 if this function has already run. */
606 if (node->finalized)
607 return;
608 if (node->needed)
610 node->next_needed = cgraph_varpool_nodes_queue;
611 cgraph_varpool_nodes_queue = node;
612 notice_global_symbol (decl);
614 node->finalized = true;
616 if (/* Externally visible variables must be output. The exception are
617 COMDAT functions that must be output only when they are needed. */
618 (TREE_PUBLIC (decl) && !DECL_COMDAT (decl))
619 /* Function whose name is output to the assembler file must be produced.
620 It is possible to assemble the name later after finalizing the function
621 and the fact is noticed in assemble_name then. */
622 || (DECL_ASSEMBLER_NAME_SET_P (decl)
623 && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))))
625 cgraph_varpool_mark_needed_node (node);
629 bool
630 cgraph_varpool_assemble_pending_decls (void)
632 bool changed = false;
634 while (cgraph_varpool_nodes_queue)
636 tree decl = cgraph_varpool_nodes_queue->decl;
637 struct cgraph_varpool_node *node = cgraph_varpool_nodes_queue;
639 cgraph_varpool_nodes_queue = cgraph_varpool_nodes_queue->next_needed;
640 if (!TREE_ASM_WRITTEN (decl))
642 assemble_variable (decl, 0, 1, 0);
643 changed = true;
645 node->next_needed = NULL;
647 return changed;
650 /* Return true when the DECL can possibly be inlined. */
651 bool
652 cgraph_function_possibly_inlined_p (tree decl)
654 if (!cgraph_global_info_ready)
655 return (DECL_INLINE (decl) && !flag_really_no_inline);
656 return DECL_POSSIBLY_INLINED (decl);
659 /* Create clone of E in the node N represented by CALL_EXPR the callgraph. */
660 struct cgraph_edge *
661 cgraph_clone_edge (struct cgraph_edge *e, struct cgraph_node *n, tree call_expr)
663 struct cgraph_edge *new = cgraph_create_edge (n, e->callee, call_expr);
665 new->inline_failed = e->inline_failed;
666 return new;
669 /* Create node representing clone of N. */
670 struct cgraph_node *
671 cgraph_clone_node (struct cgraph_node *n)
673 struct cgraph_node *new = cgraph_create_node ();
674 struct cgraph_edge *e;
676 new->decl = n->decl;
677 new->origin = n->origin;
678 if (new->origin)
680 new->next_nested = new->origin->nested;
681 new->origin->nested = new;
683 new->analyzed = n->analyzed;
684 new->local = n->local;
685 new->global = n->global;
686 new->rtl = n->rtl;
688 for (e = n->callees;e; e=e->next_callee)
689 cgraph_clone_edge (e, new, e->call_expr);
691 new->next_clone = n->next_clone;
692 n->next_clone = new;
694 return new;
697 /* NODE is no longer nested function; update cgraph accordingly. */
698 void
699 cgraph_unnest_node (struct cgraph_node *node)
701 struct cgraph_node **node2 = &node->origin->nested;
702 gcc_assert (node->origin);
704 while (*node2 != node)
705 node2 = &(*node2)->next_nested;
706 *node2 = node->next_nested;
707 node->origin = NULL;
709 #include "gt-cgraph.h"