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 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 /* Number of edges in the current function. */
72 /* First edge in the deleted edges chain. */
74 edge first_deleted_edge;
75 static basic_block first_deleted_block;
77 /* The basic block array. */
79 varray_type basic_block_info;
81 /* The special entry and exit blocks. */
83 struct basic_block_def entry_exit_blocks[2]
91 NULL, /* cond_local_set */
92 NULL, /* global_live_at_start */
93 NULL, /* global_live_at_end */
95 ENTRY_BLOCK, /* index */
104 NULL, /* head_tree */
108 NULL, /* local_set */
109 NULL, /* cond_local_set */
110 NULL, /* global_live_at_start */
111 NULL, /* global_live_at_end */
113 EXIT_BLOCK, /* index */
121 void debug_flow_info PARAMS ((void));
122 static void free_edge PARAMS ((edge));
124 /* Called once at initialization time. */
129 static int initialized;
131 first_deleted_edge = 0;
132 first_deleted_block = 0;
137 gcc_obstack_init (&flow_obstack);
138 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
143 obstack_free (&flow_obstack, flow_firstobj);
144 flow_firstobj = (char *) obstack_alloc (&flow_obstack, 0);
148 /* Helper function for remove_edge and clear_edges. Frees edge structure
149 without actually unlinking it from the pred/succ lists. */
156 memset (e, 0, sizeof *e);
157 e->succ_next = first_deleted_edge;
158 first_deleted_edge = e;
161 /* Free the memory associated with the edge structures. */
169 for (i = 0; i < n_basic_blocks; ++i)
171 basic_block bb = BASIC_BLOCK (i);
176 edge next = e->succ_next;
186 e = ENTRY_BLOCK_PTR->succ;
189 edge next = e->succ_next;
195 EXIT_BLOCK_PTR->pred = NULL;
196 ENTRY_BLOCK_PTR->succ = NULL;
202 /* Allocate memory for basic_block. */
209 if (first_deleted_block)
211 bb = first_deleted_block;
212 first_deleted_block = (basic_block) bb->succ;
217 bb = (basic_block) obstack_alloc (&flow_obstack, sizeof *bb);
218 memset (bb, 0, sizeof *bb);
223 /* Remove block B from the basic block array and compact behind it. */
229 int i, n = n_basic_blocks;
231 for (i = b->index; i + 1 < n; ++i)
233 basic_block x = BASIC_BLOCK (i + 1);
238 /* Invalidate data to make bughunting easier. */
239 memset (b, 0, sizeof *b);
241 basic_block_info->num_elements--;
243 b->succ = (edge) first_deleted_block;
244 first_deleted_block = (basic_block) b;
247 /* Create an edge connecting SRC and DST with FLAGS optionally using
248 edge cache CACHE. Return the new edge, NULL if already exist. */
251 cached_make_edge (edge_cache, src, dst, flags)
253 basic_block src, dst;
259 /* Don't bother with edge cache for ENTRY or EXIT, if there aren't that
260 many edges to them, or we didn't allocate memory for it. */
261 use_edge_cache = (edge_cache
262 && src != ENTRY_BLOCK_PTR && dst != EXIT_BLOCK_PTR);
264 /* Make sure we don't add duplicate edges. */
265 switch (use_edge_cache)
268 /* Quick test for non-existence of the edge. */
269 if (! TEST_BIT (edge_cache[src->index], dst->index))
272 /* The edge exists; early exit if no work to do. */
278 for (e = src->succ; e; e = e->succ_next)
287 if (first_deleted_edge)
289 e = first_deleted_edge;
290 first_deleted_edge = e->succ_next;
294 e = (edge) obstack_alloc (&flow_obstack, sizeof *e);
295 memset (e, 0, sizeof *e);
299 e->succ_next = src->succ;
300 e->pred_next = dst->pred;
309 SET_BIT (edge_cache[src->index], dst->index);
314 /* Create an edge connecting SRC and DEST with flags FLAGS. Return newly
315 created edge or NULL if already exist. */
318 make_edge (src, dest, flags)
319 basic_block src, dest;
322 return cached_make_edge (NULL, src, dest, flags);
325 /* Create an edge connecting SRC to DEST and set probability by knowing
326 that it is the single edge leaving SRC. */
329 make_single_succ_edge (src, dest, flags)
330 basic_block src, dest;
333 edge e = make_edge (src, dest, flags);
335 e->probability = REG_BR_PROB_BASE;
336 e->count = src->count;
340 /* This function will remove an edge from the flow graph. */
346 edge last_pred = NULL;
347 edge last_succ = NULL;
349 basic_block src, dest;
353 for (tmp = src->succ; tmp && tmp != e; tmp = tmp->succ_next)
359 last_succ->succ_next = e->succ_next;
361 src->succ = e->succ_next;
363 for (tmp = dest->pred; tmp && tmp != e; tmp = tmp->pred_next)
369 last_pred->pred_next = e->pred_next;
371 dest->pred = e->pred_next;
376 /* Redirect an edge's successor from one block to another. */
379 redirect_edge_succ (e, new_succ)
381 basic_block new_succ;
385 /* Disconnect the edge from the old successor block. */
386 for (pe = &e->dest->pred; *pe != e; pe = &(*pe)->pred_next)
388 *pe = (*pe)->pred_next;
390 /* Reconnect the edge to the new successor block. */
391 e->pred_next = new_succ->pred;
396 /* Like previous but avoid possible duplicate edge. */
399 redirect_edge_succ_nodup (e, new_succ)
401 basic_block new_succ;
405 /* Check whether the edge is already present. */
406 for (s = e->src->succ; s; s = s->succ_next)
407 if (s->dest == new_succ && s != e)
412 s->flags |= e->flags;
413 s->probability += e->probability;
414 s->count += e->count;
419 redirect_edge_succ (e, new_succ);
424 /* Redirect an edge's predecessor from one block to another. */
427 redirect_edge_pred (e, new_pred)
429 basic_block new_pred;
433 /* Disconnect the edge from the old predecessor block. */
434 for (pe = &e->src->succ; *pe != e; pe = &(*pe)->succ_next)
437 *pe = (*pe)->succ_next;
439 /* Reconnect the edge to the new predecessor block. */
440 e->succ_next = new_pred->succ;
449 ENTRY_BLOCK_PTR->flags = 0;
450 EXIT_BLOCK_PTR->flags = 0;
451 for (i = 0; i < n_basic_blocks; i++)
452 BASIC_BLOCK (i)->flags = 0;
456 dump_flow_info (file)
460 static const char * const reg_class_names[] = REG_CLASS_NAMES;
462 fprintf (file, "%d registers.\n", max_regno);
463 for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
466 enum reg_class class, altclass;
468 fprintf (file, "\nRegister %d used %d times across %d insns",
469 i, REG_N_REFS (i), REG_LIVE_LENGTH (i));
470 if (REG_BASIC_BLOCK (i) >= 0)
471 fprintf (file, " in block %d", REG_BASIC_BLOCK (i));
473 fprintf (file, "; set %d time%s", REG_N_SETS (i),
474 (REG_N_SETS (i) == 1) ? "" : "s");
475 if (REG_USERVAR_P (regno_reg_rtx[i]))
476 fprintf (file, "; user var");
477 if (REG_N_DEATHS (i) != 1)
478 fprintf (file, "; dies in %d places", REG_N_DEATHS (i));
479 if (REG_N_CALLS_CROSSED (i) == 1)
480 fprintf (file, "; crosses 1 call");
481 else if (REG_N_CALLS_CROSSED (i))
482 fprintf (file, "; crosses %d calls", REG_N_CALLS_CROSSED (i));
483 if (PSEUDO_REGNO_BYTES (i) != UNITS_PER_WORD)
484 fprintf (file, "; %d bytes", PSEUDO_REGNO_BYTES (i));
486 class = reg_preferred_class (i);
487 altclass = reg_alternate_class (i);
488 if (class != GENERAL_REGS || altclass != ALL_REGS)
490 if (altclass == ALL_REGS || class == ALL_REGS)
491 fprintf (file, "; pref %s", reg_class_names[(int) class]);
492 else if (altclass == NO_REGS)
493 fprintf (file, "; %s or none", reg_class_names[(int) class]);
495 fprintf (file, "; pref %s, else %s",
496 reg_class_names[(int) class],
497 reg_class_names[(int) altclass]);
500 if (REG_POINTER (regno_reg_rtx[i]))
501 fprintf (file, "; pointer");
502 fprintf (file, ".\n");
505 fprintf (file, "\n%d basic blocks, %d edges.\n", n_basic_blocks, n_edges);
506 for (i = 0; i < n_basic_blocks; i++)
508 basic_block bb = BASIC_BLOCK (i);
511 fprintf (file, "\nBasic block %d: first insn %d, last %d, ",
512 i, INSN_UID (bb->head), INSN_UID (bb->end));
513 fprintf (file, "loop_depth %d, count ", bb->loop_depth);
514 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, bb->count);
515 fprintf (file, ", freq %i.\n", bb->frequency);
517 fprintf (file, "Predecessors: ");
518 for (e = bb->pred; e; e = e->pred_next)
519 dump_edge_info (file, e, 0);
521 fprintf (file, "\nSuccessors: ");
522 for (e = bb->succ; e; e = e->succ_next)
523 dump_edge_info (file, e, 1);
525 fprintf (file, "\nRegisters live at start:");
526 dump_regset (bb->global_live_at_start, file);
528 fprintf (file, "\nRegisters live at end:");
529 dump_regset (bb->global_live_at_end, file);
540 dump_flow_info (stderr);
544 dump_edge_info (file, e, do_succ)
549 basic_block side = (do_succ ? e->dest : e->src);
551 if (side == ENTRY_BLOCK_PTR)
552 fputs (" ENTRY", file);
553 else if (side == EXIT_BLOCK_PTR)
554 fputs (" EXIT", file);
556 fprintf (file, " %d", side->index);
559 fprintf (file, " [%.1f%%] ", e->probability * 100.0 / REG_BR_PROB_BASE);
563 fprintf (file, " count:");
564 fprintf (file, HOST_WIDEST_INT_PRINT_DEC, e->count);
569 static const char * const bitnames[]
570 = {"fallthru", "ab", "abcall", "eh", "fake", "dfs_back"};
572 int i, flags = e->flags;
575 for (i = 0; flags; i++)
576 if (flags & (1 << i))
582 if (i < (int) ARRAY_SIZE (bitnames))
583 fputs (bitnames[i], file);
585 fprintf (file, "%d", i);
593 /* Simple routines to easily allocate AUX fields of basic blocks. */
595 static struct obstack block_aux_obstack;
596 static void *first_block_aux_obj = 0;
597 static struct obstack edge_aux_obstack;
598 static void *first_edge_aux_obj = 0;
600 /* Allocate an memory block of SIZE as BB->aux. The obstack must
601 be first initialized by alloc_aux_for_blocks. */
604 alloc_aux_for_block (bb, size)
608 /* Verify that aux field is clear. */
609 if (bb->aux || !first_block_aux_obj)
611 bb->aux = obstack_alloc (&block_aux_obstack, size);
612 memset (bb->aux, 0, size);
615 /* Initialize the block_aux_obstack and if SIZE is nonzero, call
616 alloc_aux_for_block for each basic block. */
619 alloc_aux_for_blocks (size)
622 static int initialized;
626 gcc_obstack_init (&block_aux_obstack);
630 /* Check whether AUX data are still allocated. */
631 else if (first_block_aux_obj)
633 first_block_aux_obj = (char *) obstack_alloc (&block_aux_obstack, 0);
638 for (i = 0; i < n_basic_blocks; i++)
639 alloc_aux_for_block (BASIC_BLOCK (i), size);
641 alloc_aux_for_block (ENTRY_BLOCK_PTR, size);
642 alloc_aux_for_block (EXIT_BLOCK_PTR, size);
646 /* Clear AUX pointers of all blocks. */
649 clear_aux_for_blocks ()
653 for (i = 0; i < n_basic_blocks; i++)
654 BASIC_BLOCK (i)->aux = NULL;
656 ENTRY_BLOCK_PTR->aux = NULL;
657 EXIT_BLOCK_PTR->aux = NULL;
660 /* Free data allocated in block_aux_obstack and clear AUX pointers
664 free_aux_for_blocks ()
666 if (!first_block_aux_obj)
668 obstack_free (&block_aux_obstack, first_block_aux_obj);
669 first_block_aux_obj = NULL;
671 clear_aux_for_blocks ();
674 /* Allocate an memory edge of SIZE as BB->aux. The obstack must
675 be first initialized by alloc_aux_for_edges. */
678 alloc_aux_for_edge (e, size)
682 /* Verify that aux field is clear. */
683 if (e->aux || !first_edge_aux_obj)
685 e->aux = obstack_alloc (&edge_aux_obstack, size);
686 memset (e->aux, 0, size);
689 /* Initialize the edge_aux_obstack and if SIZE is nonzero, call
690 alloc_aux_for_edge for each basic edge. */
693 alloc_aux_for_edges (size)
696 static int initialized;
700 gcc_obstack_init (&edge_aux_obstack);
704 /* Check whether AUX data are still allocated. */
705 else if (first_edge_aux_obj)
708 first_edge_aux_obj = (char *) obstack_alloc (&edge_aux_obstack, 0);
712 for (i = -1; i < n_basic_blocks; i++)
718 bb = BASIC_BLOCK (i);
720 bb = ENTRY_BLOCK_PTR;
722 for (e = bb->succ; e; e = e->succ_next)
723 alloc_aux_for_edge (e, size);
728 /* Clear AUX pointers of all edges. */
731 clear_aux_for_edges ()
735 for (i = -1; i < n_basic_blocks; i++)
741 bb = BASIC_BLOCK (i);
743 bb = ENTRY_BLOCK_PTR;
745 for (e = bb->succ; e; e = e->succ_next)
750 /* Free data allocated in edge_aux_obstack and clear AUX pointers
754 free_aux_for_edges ()
756 if (!first_edge_aux_obj)
758 obstack_free (&edge_aux_obstack, first_edge_aux_obj);
759 first_edge_aux_obj = NULL;
761 clear_aux_for_edges ();