1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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
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 COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains low level functions to manipulate the CFG and
23 analyze it. All other modules should not transform the datastructure
24 directly and use abstraction instead. The file is supposed to be
25 ordered bottom-up and should not contain any code dependent on a
26 particular intermediate language (RTL or trees).
28 Available functionality:
29 - Initialization/deallocation
30 init_flow, clear_edges
31 - Low level basic block manipulation
32 alloc_block, expunge_block
34 make_edge, make_single_succ_edge, cached_make_edge, remove_edge
35 - Low level edge redirection (without updating instruction chain)
36 redirect_edge_succ, redirect_edge_succ_nodup, redirect_edge_pred
37 - Dumping and debugging
38 dump_flow_info, debug_flow_info, dump_edge_info
39 - Allocation of AUX fields for basic blocks
40 alloc_aux_for_blocks, free_aux_for_blocks, alloc_aux_for_block
48 #include "hard-reg-set.h"
49 #include "basic-block.h"
59 /* The obstack on which the flow graph components are allocated. */
61 struct obstack flow_obstack;
62 static char *flow_firstobj;
64 /* Number of basic blocks in the current function. */
68 /* First free basic block number. */
72 /* Number of edges in the current function. */
76 /* First edge in the deleted edges chain. */
78 edge first_deleted_edge;
79 static basic_block first_deleted_block;
81 /* The basic block array. */
83 varray_type basic_block_info;
85 /* The special entry and exit blocks. */
87 struct basic_block_def entry_exit_blocks[2]
95 NULL, /* cond_local_set */
96 NULL, /* global_live_at_start */
97 NULL, /* global_live_at_end */
99 ENTRY_BLOCK, /* index */
101 EXIT_BLOCK_PTR, /* next_bb */
103 NULL, /* loop_father */
111 NULL, /* head_tree */
115 NULL, /* local_set */
116 NULL, /* cond_local_set */
117 NULL, /* global_live_at_start */
118 NULL, /* global_live_at_end */
120 EXIT_BLOCK, /* index */
121 ENTRY_BLOCK_PTR, /* prev_bb */
124 NULL, /* loop_father */
131 void debug_flow_info PARAMS ((void));
132 static void free_edge PARAMS ((edge));
134 /* Called once at initialization time. */
139 static int initialized;
141 first_deleted_edge = 0;
142 first_deleted_block = 0;
147 gcc_obstack_init (&flow_obstack);
148 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
153 obstack_free (&flow_obstack, flow_firstobj);
154 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
158 /* Helper function for remove_edge and clear_edges. Frees edge structure
159 without actually unlinking it from the pred/succ lists. */
166 memset (e, 0, sizeof *e);
167 e->succ_next = first_deleted_edge;
168 first_deleted_edge = e;
171 /* Free the memory associated with the edge structures. */
185 edge next = e->succ_next;
195 e = ENTRY_BLOCK_PTR->succ;
198 edge next = e->succ_next;
204 EXIT_BLOCK_PTR->pred = NULL;
205 ENTRY_BLOCK_PTR->succ = NULL;
211 /* Allocate memory for basic_block. */
218 if (first_deleted_block)
220 bb = first_deleted_block;
221 first_deleted_block = (basic_block) bb->succ;
226 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof *bb);
227 memset (bb, 0, sizeof *bb);
232 /* Link block B to chain after AFTER. */
234 link_block (b, after)
235 basic_block b, after;
237 b->next_bb = after->next_bb;
240 b->next_bb->prev_bb = b;
243 /* Unlink block B from chain. */
248 b->next_bb->prev_bb = b->prev_bb;
249 b->prev_bb->next_bb = b->next_bb;
252 /* Sequentially order blocks and compact the arrays. */
262 BASIC_BLOCK (i) = bb;
267 if (i != n_basic_blocks)
270 last_basic_block = n_basic_blocks;
274 /* Remove block B from the basic block array. */
281 BASIC_BLOCK (b->index) = NULL;
284 /* Invalidate data to make bughunting easier. */
285 memset (b, 0, sizeof *b);
287 b->succ = (edge) first_deleted_block;
288 first_deleted_block = (basic_block) b;
291 /* Create an edge connecting SRC and DST with FLAGS optionally using
292 edge cache CACHE. Return the new edge, NULL if already exist. */
295 cached_make_edge (edge_cache, src, dst, flags)
297 basic_block src, dst;
303 /* Don't bother with edge cache for ENTRY or EXIT, if there aren't that
304 many edges to them, or we didn't allocate memory for it. */
305 use_edge_cache = (edge_cache
306 && src != ENTRY_BLOCK_PTR && dst != EXIT_BLOCK_PTR);
308 /* Make sure we don't add duplicate edges. */
309 switch (use_edge_cache)
312 /* Quick test for non-existence of the edge. */
313 if (! TEST_BIT (edge_cache[src->index], dst->index))
316 /* The edge exists; early exit if no work to do. */
322 for (e = src->succ; e; e = e->succ_next)
331 if (first_deleted_edge)
333 e = first_deleted_edge;
334 first_deleted_edge = e->succ_next;
338 e = (edge) obstack_alloc (&flow_obstack, sizeof *e);
339 memset (e, 0, sizeof *e);
343 e->succ_next = src->succ;
344 e->pred_next = dst->pred;
353 SET_BIT (edge_cache[src->index], dst->index);
358 /* Create an edge connecting SRC and DEST with flags FLAGS. Return newly
359 created edge or NULL if already exist. */
362 make_edge (src, dest, flags)
363 basic_block src, dest;
366 return cached_make_edge (NULL, src, dest, flags);
369 /* Create an edge connecting SRC to DEST and set probability by knowing
370 that it is the single edge leaving SRC. */
373 make_single_succ_edge (src, dest, flags)
374 basic_block src, dest;
377 edge e = make_edge (src, dest, flags);
379 e->probability = REG_BR_PROB_BASE;
380 e->count = src->count;
384 /* This function will remove an edge from the flow graph. */
390 edge last_pred = NULL;
391 edge last_succ = NULL;
393 basic_block src, dest;
397 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
403 last_succ->succ_next = e->succ_next;
405 src->succ = e->succ_next;
407 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
413 last_pred->pred_next = e->pred_next;
415 dest->pred = e->pred_next;
420 /* Redirect an edge's successor from one block to another. */
423 redirect_edge_succ (e, new_succ)
425 basic_block new_succ;
429 /* Disconnect the edge from the old successor block. */
430 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
432 *pe = (*pe)->pred_next;
434 /* Reconnect the edge to the new successor block. */
435 e->pred_next = new_succ->pred;
440 /* Like previous but avoid possible duplicate edge. */
443 redirect_edge_succ_nodup (e, new_succ)
445 basic_block new_succ;
449 /* Check whether the edge is already present. */
450 for (s = e->src->succ; s; s = s->succ_next)
451 if (s->dest == new_succ && s != e)
456 s->flags |= e->flags;
457 s->probability += e->probability;
458 if (s->probability > REG_BR_PROB_BASE)
459 s->probability = REG_BR_PROB_BASE;
460 s->count += e->count;
465 redirect_edge_succ (e, new_succ);
470 /* Redirect an edge's predecessor from one block to another. */
473 redirect_edge_pred (e, new_pred)
475 basic_block new_pred;
479 /* Disconnect the edge from the old predecessor block. */
480 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
483 *pe = (*pe)->succ_next;
485 /* Reconnect the edge to the new predecessor block. */
486 e->succ_next = new_pred->succ;
496 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
501 dump_flow_info (file)
505 int max_regno = max_reg_num ();
507 static const char * const reg_class_names[] = REG_CLASS_NAMES;
509 fprintf (file, "%d registers.\n", max_regno);
510 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
513 enum reg_class class, altclass;
515 fprintf (file, "\nRegister %d used %d times across %d insns",
516 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
517 if (REG_BASIC_BLOCK (i) >= 0)
518 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
520 fprintf (file, "; set %d time%s", REG_N_SETS (i),
521 (REG_N_SETS (i) == 1) ? "" : "s");
522 if (regno_reg_rtx[i] != NULL && REG_USERVAR_P (regno_reg_rtx[i]))
523 fprintf (file, "; user var");
524 if (REG_N_DEATHS (i) != 1)
525 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
526 if (REG_N_CALLS_CROSSED (i) == 1)
527 fprintf (file, "; crosses 1 call");
528 else if (REG_N_CALLS_CROSSED (i))
529 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
530 if (regno_reg_rtx[i] != NULL
531 && PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
532 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
534 class = reg_preferred_class (i);
535 altclass = reg_alternate_class (i);
536 if (class != GENERAL_REGS || altclass != ALL_REGS)
538 if (altclass == ALL_REGS || class == ALL_REGS)
539 fprintf (file, "; pref %s", reg_class_names[(int) class]);
540 else if (altclass == NO_REGS)
541 fprintf (file, "; %s or none", reg_class_names[(int) class]);
543 fprintf (file, "; pref %s, else %s",
544 reg_class_names[(int) class],
545 reg_class_names[(int) altclass]);
548 if (regno_reg_rtx[i] != NULL && REG_POINTER (regno_reg_rtx[i]))
549 fprintf (file, "; pointer");
550 fprintf (file, ".\n");
553 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
560 fprintf (file, "\nBasic block %d: first insn %d, last %d, ",
561 bb->index, INSN_UID (bb->head), INSN_UID (bb->end));
562 fprintf (file, "prev %d, next %d, ",
563 bb->prev_bb->index, bb->next_bb->index);
564 fprintf (file, "loop_depth %d, count ", bb->loop_depth);
565 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, bb->count);
566 fprintf (file, ", freq %i", bb->frequency);
567 if (maybe_hot_bb_p (bb))
568 fprintf (file, ", maybe hot");
569 if (probably_never_executed_bb_p (bb))
570 fprintf (file, ", probably never executed");
571 fprintf (file, ".\n");
573 fprintf (file, "Predecessors: ");
574 for (e = bb->pred; e; e = e->pred_next)
575 dump_edge_info (file, e, 0);
577 fprintf (file, "\nSuccessors: ");
578 for (e = bb->succ; e; e = e->succ_next)
579 dump_edge_info (file, e, 1);
581 fprintf (file, "\nRegisters live at start:");
582 dump_regset (bb->global_live_at_start, file);
584 fprintf (file, "\nRegisters live at end:");
585 dump_regset (bb->global_live_at_end, file);
589 /* Check the consistency of profile information. We can't do that
590 in verify_flow_info, as the counts may get invalid for incompletely
591 solved graphs, later elliminating of conditionals or roundoff errors.
592 It is still practical to have them reported for debugging of simple
595 for (e = bb->succ; e; e = e->succ_next)
596 sum += e->probability;
597 if (bb->succ && abs (sum - REG_BR_PROB_BASE) > 100)
598 fprintf (file, "Invalid sum of outgoing probabilities %.1f%%\n",
599 sum * 100.0 / REG_BR_PROB_BASE);
601 for (e = bb->pred; e; e = e->pred_next)
602 sum += EDGE_FREQUENCY (e);
603 if (abs (sum - bb->frequency) > 100)
605 "Invalid sum of incomming frequencies %i, should be %i\n",
608 for (e = bb->pred; e; e = e->pred_next)
610 if (lsum - bb->count > 100 || lsum - bb->count < -100)
611 fprintf (file, "Invalid sum of incomming counts %i, should be %i\n",
612 (int)lsum, (int)bb->count);
614 for (e = bb->succ; e; e = e->succ_next)
616 if (bb->succ && (lsum - bb->count > 100 || lsum - bb->count < -100))
617 fprintf (file, "Invalid sum of incomming counts %i, should be %i\n",
618 (int)lsum, (int)bb->count);
627 dump_flow_info (stderr);
631 dump_edge_info (file, e, do_succ)
636 basic_block side = (do_succ ? e->dest : e->src);
638 if (side == ENTRY_BLOCK_PTR)
639 fputs (" ENTRY", file);
640 else if (side == EXIT_BLOCK_PTR)
641 fputs (" EXIT", file);
643 fprintf (file, " %d", side->index);
646 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
650 fprintf (file, " count:");
651 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, e->count);
656 static const char * const bitnames[]
657 = {"fallthru", "ab", "abcall", "eh", "fake", "dfs_back", "can_fallthru"};
659 int i, flags = e->flags;
662 for (i = 0; flags; i++)
663 if (flags & (1 << i))
669 if (i < (int) ARRAY_SIZE (bitnames))
670 fputs (bitnames[i], file);
672 fprintf (file, "%d", i);
680 /* Simple routines to easily allocate AUX fields of basic blocks. */
682 static struct obstack block_aux_obstack;
683 static void *first_block_aux_obj = 0;
684 static struct obstack edge_aux_obstack;
685 static void *first_edge_aux_obj = 0;
687 /* Allocate a memory block of SIZE as BB->aux. The obstack must
688 be first initialized by alloc_aux_for_blocks. */
691 alloc_aux_for_block (bb, size)
695 /* Verify that aux field is clear. */
696 if (bb->aux || !first_block_aux_obj)
698 bb->aux = obstack_alloc (&block_aux_obstack, size);
699 memset (bb->aux, 0, size);
702 /* Initialize the block_aux_obstack and if SIZE is nonzero, call
703 alloc_aux_for_block for each basic block. */
706 alloc_aux_for_blocks (size)
709 static int initialized;
713 gcc_obstack_init (&block_aux_obstack);
717 /* Check whether AUX data are still allocated. */
718 else if (first_block_aux_obj)
720 first_block_aux_obj = (char *) obstack_alloc (&block_aux_obstack, 0);
725 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
726 alloc_aux_for_block (bb, size);
730 /* Clear AUX pointers of all blocks. */
733 clear_aux_for_blocks ()
737 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
741 /* Free data allocated in block_aux_obstack and clear AUX pointers
745 free_aux_for_blocks ()
747 if (!first_block_aux_obj)
749 obstack_free (&block_aux_obstack, first_block_aux_obj);
750 first_block_aux_obj = NULL;
752 clear_aux_for_blocks ();
755 /* Allocate a memory edge of SIZE as BB->aux. The obstack must
756 be first initialized by alloc_aux_for_edges. */
759 alloc_aux_for_edge (e, size)
763 /* Verify that aux field is clear. */
764 if (e->aux || !first_edge_aux_obj)
766 e->aux = obstack_alloc (&edge_aux_obstack, size);
767 memset (e->aux, 0, size);
770 /* Initialize the edge_aux_obstack and if SIZE is nonzero, call
771 alloc_aux_for_edge for each basic edge. */
774 alloc_aux_for_edges (size)
777 static int initialized;
781 gcc_obstack_init (&edge_aux_obstack);
785 /* Check whether AUX data are still allocated. */
786 else if (first_edge_aux_obj)
789 first_edge_aux_obj = (char *) obstack_alloc (&edge_aux_obstack, 0);
794 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
798 for (e = bb->succ; e; e = e->succ_next)
799 alloc_aux_for_edge (e, size);
804 /* Clear AUX pointers of all edges. */
807 clear_aux_for_edges ()
812 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
814 for (e = bb->succ; e; e = e->succ_next)
819 /* Free data allocated in edge_aux_obstack and clear AUX pointers
823 free_aux_for_edges ()
825 if (!first_edge_aux_obj)
827 obstack_free (&edge_aux_obstack, first_edge_aux_obj);
828 first_edge_aux_obj = NULL;
830 clear_aux_for_edges ();