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ca6c03ca JH |
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. | |
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 low level functions to manipulate with CFG and analyze it | |
23 | that are aware of RTL intermediate language. | |
24 | ||
25 | Available functionality: | |
26 | - CFG aware instruction chain manipulation | |
27 | delete_insn, delete_insn_chain | |
28 | - Basic block manipulation | |
29 | create_basic_block, flow_delete_block, split_block, merge_blocks_nomove | |
30 | - Infrastructure to determine quickly basic block for instruction. | |
31 | compute_bb_for_insn, update_bb_for_insn, set_block_for_insn, | |
32 | - Edge redirection with updating and optimizing instruction chain | |
33 | block_label, redirect_edge_and_branch, | |
34 | redirect_edge_and_branch_force, tidy_fallthru_edge, force_nonfallthru | |
35 | - Edge splitting and commiting to edges | |
36 | split_edge, insert_insn_on_edge, commit_edge_insertions | |
eaec9b3d | 37 | - Dumping and debugging |
ca6c03ca JH |
38 | print_rtl_with_bb, dump_bb, debug_bb, debug_bb_n |
39 | - Consistency checking | |
40 | verify_flow_info | |
41 | - CFG updating after constant propagation | |
42 | purge_dead_edges, purge_all_dead_edges | |
43 | */ | |
44 | \f | |
45 | #include "config.h" | |
46 | #include "system.h" | |
47 | #include "tree.h" | |
48 | #include "rtl.h" | |
49 | #include "hard-reg-set.h" | |
50 | #include "basic-block.h" | |
51 | #include "regs.h" | |
52 | #include "flags.h" | |
53 | #include "output.h" | |
54 | #include "function.h" | |
55 | #include "except.h" | |
56 | #include "toplev.h" | |
57 | #include "tm_p.h" | |
58 | #include "obstack.h" | |
59 | ||
60 | /* Stubs in case we haven't got a return insn. */ | |
61 | #ifndef HAVE_return | |
62 | #define HAVE_return 0 | |
63 | #define gen_return() NULL_RTX | |
64 | #endif | |
65 | ||
66 | /* The basic block structure for every insn, indexed by uid. */ | |
67 | ||
68 | varray_type basic_block_for_insn; | |
69 | ||
70 | /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */ | |
71 | /* ??? Should probably be using LABEL_NUSES instead. It would take a | |
72 | bit of surgery to be able to use or co-opt the routines in jump. */ | |
73 | ||
74 | rtx label_value_list; | |
75 | rtx tail_recursion_label_list; | |
76 | ||
77 | static int can_delete_note_p PARAMS ((rtx)); | |
78 | static int can_delete_label_p PARAMS ((rtx)); | |
79 | static void commit_one_edge_insertion PARAMS ((edge)); | |
80 | static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block)); | |
81 | static rtx last_loop_beg_note PARAMS ((rtx)); | |
82 | static bool back_edge_of_syntactic_loop_p PARAMS ((basic_block, basic_block)); | |
83 | static basic_block force_nonfallthru_and_redirect PARAMS ((edge, basic_block)); | |
84 | \f | |
85 | /* Return true if NOTE is not one of the ones that must be kept paired, | |
86 | so that we may simply delete them. */ | |
87 | ||
88 | static int | |
89 | can_delete_note_p (note) | |
90 | rtx note; | |
91 | { | |
92 | return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED | |
93 | || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK); | |
94 | } | |
95 | ||
96 | /* True if a given label can be deleted. */ | |
97 | ||
98 | static int | |
99 | can_delete_label_p (label) | |
100 | rtx label; | |
101 | { | |
102 | rtx x; | |
103 | ||
104 | if (LABEL_PRESERVE_P (label)) | |
105 | return 0; | |
106 | ||
107 | for (x = forced_labels; x; x = XEXP (x, 1)) | |
108 | if (label == XEXP (x, 0)) | |
109 | return 0; | |
110 | for (x = label_value_list; x; x = XEXP (x, 1)) | |
111 | if (label == XEXP (x, 0)) | |
112 | return 0; | |
113 | for (x = exception_handler_labels; x; x = XEXP (x, 1)) | |
114 | if (label == XEXP (x, 0)) | |
115 | return 0; | |
116 | ||
117 | /* User declared labels must be preserved. */ | |
118 | if (LABEL_NAME (label) != 0) | |
119 | return 0; | |
120 | ||
121 | return 1; | |
122 | } | |
123 | ||
124 | /* Delete INSN by patching it out. Return the next insn. */ | |
125 | ||
126 | rtx | |
127 | delete_insn (insn) | |
128 | rtx insn; | |
129 | { | |
130 | rtx next = NEXT_INSN (insn); | |
131 | rtx note; | |
132 | bool really_delete = true; | |
133 | ||
134 | if (GET_CODE (insn) == CODE_LABEL) | |
135 | { | |
136 | /* Some labels can't be directly removed from the INSN chain, as they | |
137 | might be references via variables, constant pool etc. | |
138 | Convert them to the special NOTE_INSN_DELETED_LABEL note. */ | |
139 | if (! can_delete_label_p (insn)) | |
140 | { | |
141 | const char *name = LABEL_NAME (insn); | |
142 | ||
143 | really_delete = false; | |
144 | PUT_CODE (insn, NOTE); | |
145 | NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL; | |
146 | NOTE_SOURCE_FILE (insn) = name; | |
147 | } | |
148 | remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels); | |
149 | } | |
150 | ||
151 | if (really_delete) | |
152 | { | |
153 | remove_insn (insn); | |
154 | INSN_DELETED_P (insn) = 1; | |
155 | } | |
156 | ||
157 | /* If deleting a jump, decrement the use count of the label. Deleting | |
158 | the label itself should happen in the normal course of block merging. */ | |
159 | if (GET_CODE (insn) == JUMP_INSN | |
160 | && JUMP_LABEL (insn) | |
161 | && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL) | |
162 | LABEL_NUSES (JUMP_LABEL (insn))--; | |
163 | ||
164 | /* Also if deleting an insn that references a label. */ | |
165 | else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX | |
166 | && GET_CODE (XEXP (note, 0)) == CODE_LABEL) | |
167 | LABEL_NUSES (XEXP (note, 0))--; | |
168 | ||
169 | if (GET_CODE (insn) == JUMP_INSN | |
170 | && (GET_CODE (PATTERN (insn)) == ADDR_VEC | |
171 | || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)) | |
172 | { | |
173 | rtx pat = PATTERN (insn); | |
174 | int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; | |
175 | int len = XVECLEN (pat, diff_vec_p); | |
176 | int i; | |
177 | ||
178 | for (i = 0; i < len; i++) | |
179 | LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--; | |
180 | } | |
181 | ||
182 | return next; | |
183 | } | |
184 | ||
185 | /* Unlink a chain of insns between START and FINISH, leaving notes | |
186 | that must be paired. */ | |
187 | ||
188 | void | |
189 | delete_insn_chain (start, finish) | |
190 | rtx start, finish; | |
191 | { | |
192 | /* Unchain the insns one by one. It would be quicker to delete all | |
193 | of these with a single unchaining, rather than one at a time, but | |
194 | we need to keep the NOTE's. */ | |
195 | ||
196 | rtx next; | |
197 | ||
198 | while (1) | |
199 | { | |
200 | next = NEXT_INSN (start); | |
201 | if (GET_CODE (start) == NOTE && !can_delete_note_p (start)) | |
202 | ; | |
203 | else | |
204 | next = delete_insn (start); | |
205 | ||
206 | if (start == finish) | |
207 | break; | |
208 | start = next; | |
209 | } | |
210 | } | |
211 | \f | |
212 | /* Create a new basic block consisting of the instructions between | |
213 | HEAD and END inclusive. This function is designed to allow fast | |
214 | BB construction - reuses the note and basic block struct | |
215 | in BB_NOTE, if any and do not grow BASIC_BLOCK chain and should | |
216 | be used directly only by CFG construction code. | |
217 | END can be NULL in to create new empty basic block before HEAD. | |
218 | Both END and HEAD can be NULL to create basic block at the end of | |
219 | INSN chain. */ | |
220 | ||
221 | basic_block | |
222 | create_basic_block_structure (index, head, end, bb_note) | |
223 | int index; | |
224 | rtx head, end, bb_note; | |
225 | { | |
226 | basic_block bb; | |
227 | ||
228 | if (bb_note | |
229 | && ! RTX_INTEGRATED_P (bb_note) | |
230 | && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL | |
231 | && bb->aux == NULL) | |
232 | { | |
233 | /* If we found an existing note, thread it back onto the chain. */ | |
234 | ||
235 | rtx after; | |
236 | ||
237 | if (GET_CODE (head) == CODE_LABEL) | |
238 | after = head; | |
239 | else | |
240 | { | |
241 | after = PREV_INSN (head); | |
242 | head = bb_note; | |
243 | } | |
244 | ||
245 | if (after != bb_note && NEXT_INSN (after) != bb_note) | |
246 | reorder_insns (bb_note, bb_note, after); | |
247 | } | |
248 | else | |
249 | { | |
250 | /* Otherwise we must create a note and a basic block structure. */ | |
251 | ||
252 | bb = alloc_block (); | |
253 | ||
254 | if (!head && !end) | |
255 | { | |
256 | head = end = bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, | |
257 | get_last_insn ()); | |
258 | } | |
259 | else if (GET_CODE (head) == CODE_LABEL && end) | |
260 | { | |
261 | bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head); | |
262 | if (head == end) | |
263 | end = bb_note; | |
264 | } | |
265 | else | |
266 | { | |
267 | bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head); | |
268 | head = bb_note; | |
269 | if (!end) | |
270 | end = head; | |
271 | } | |
272 | NOTE_BASIC_BLOCK (bb_note) = bb; | |
273 | } | |
274 | ||
275 | /* Always include the bb note in the block. */ | |
276 | if (NEXT_INSN (end) == bb_note) | |
277 | end = bb_note; | |
278 | ||
279 | bb->head = head; | |
280 | bb->end = end; | |
281 | bb->index = index; | |
282 | BASIC_BLOCK (index) = bb; | |
283 | if (basic_block_for_insn) | |
284 | update_bb_for_insn (bb); | |
285 | ||
286 | /* Tag the block so that we know it has been used when considering | |
287 | other basic block notes. */ | |
288 | bb->aux = bb; | |
289 | ||
290 | return bb; | |
291 | } | |
292 | ||
293 | /* Create new basic block consisting of instructions in between HEAD and | |
eaec9b3d | 294 | END and place it to the BB chain at position INDEX. |
ca6c03ca JH |
295 | END can be NULL in to create new empty basic block before HEAD. |
296 | Both END and HEAD can be NULL to create basic block at the end of | |
297 | INSN chain. */ | |
298 | ||
299 | basic_block | |
300 | create_basic_block (index, head, end) | |
301 | int index; | |
302 | rtx head, end; | |
303 | { | |
304 | basic_block bb; | |
305 | int i; | |
306 | ||
307 | /* Place the new block just after the block being split. */ | |
308 | VARRAY_GROW (basic_block_info, ++n_basic_blocks); | |
309 | ||
310 | /* Some parts of the compiler expect blocks to be number in | |
311 | sequential order so insert the new block immediately after the | |
312 | block being split.. */ | |
313 | for (i = n_basic_blocks - 1; i > index; --i) | |
314 | { | |
315 | basic_block tmp = BASIC_BLOCK (i - 1); | |
316 | BASIC_BLOCK (i) = tmp; | |
317 | tmp->index = i; | |
318 | } | |
319 | ||
320 | bb = create_basic_block_structure (index, head, end, NULL); | |
321 | bb->aux = NULL; | |
322 | return bb; | |
323 | } | |
324 | \f | |
325 | /* Delete the insns in a (non-live) block. We physically delete every | |
326 | non-deleted-note insn, and update the flow graph appropriately. | |
327 | ||
328 | Return nonzero if we deleted an exception handler. */ | |
329 | ||
330 | /* ??? Preserving all such notes strikes me as wrong. It would be nice | |
331 | to post-process the stream to remove empty blocks, loops, ranges, etc. */ | |
332 | ||
333 | int | |
334 | flow_delete_block (b) | |
335 | basic_block b; | |
336 | { | |
337 | int deleted_handler = 0; | |
338 | rtx insn, end, tmp; | |
339 | ||
340 | /* If the head of this block is a CODE_LABEL, then it might be the | |
341 | label for an exception handler which can't be reached. | |
342 | ||
343 | We need to remove the label from the exception_handler_label list | |
344 | and remove the associated NOTE_INSN_EH_REGION_BEG and | |
345 | NOTE_INSN_EH_REGION_END notes. */ | |
346 | ||
347 | insn = b->head; | |
348 | ||
349 | never_reached_warning (insn); | |
350 | ||
351 | if (GET_CODE (insn) == CODE_LABEL) | |
352 | maybe_remove_eh_handler (insn); | |
353 | ||
354 | /* Include any jump table following the basic block. */ | |
355 | end = b->end; | |
356 | if (GET_CODE (end) == JUMP_INSN | |
357 | && (tmp = JUMP_LABEL (end)) != NULL_RTX | |
358 | && (tmp = NEXT_INSN (tmp)) != NULL_RTX | |
359 | && GET_CODE (tmp) == JUMP_INSN | |
360 | && (GET_CODE (PATTERN (tmp)) == ADDR_VEC | |
361 | || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC)) | |
362 | end = tmp; | |
363 | ||
364 | /* Include any barrier that may follow the basic block. */ | |
365 | tmp = next_nonnote_insn (end); | |
366 | if (tmp && GET_CODE (tmp) == BARRIER) | |
367 | end = tmp; | |
368 | ||
369 | /* Selectively delete the entire chain. */ | |
370 | b->head = NULL; | |
371 | delete_insn_chain (insn, end); | |
372 | ||
373 | /* Remove the edges into and out of this block. Note that there may | |
374 | indeed be edges in, if we are removing an unreachable loop. */ | |
375 | while (b->pred != NULL) | |
376 | remove_edge (b->pred); | |
377 | while (b->succ != NULL) | |
378 | remove_edge (b->succ); | |
379 | ||
380 | b->pred = NULL; | |
381 | b->succ = NULL; | |
382 | ||
383 | /* Remove the basic block from the array, and compact behind it. */ | |
384 | expunge_block (b); | |
385 | ||
386 | return deleted_handler; | |
387 | } | |
388 | \f | |
389 | /* Records the basic block struct in BB_FOR_INSN, for every instruction | |
390 | indexed by INSN_UID. MAX is the size of the array. */ | |
391 | ||
392 | void | |
393 | compute_bb_for_insn (max) | |
394 | int max; | |
395 | { | |
396 | int i; | |
397 | ||
398 | if (basic_block_for_insn) | |
399 | VARRAY_FREE (basic_block_for_insn); | |
400 | VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn"); | |
401 | ||
402 | for (i = 0; i < n_basic_blocks; ++i) | |
403 | { | |
404 | basic_block bb = BASIC_BLOCK (i); | |
405 | rtx insn, end; | |
406 | ||
407 | end = bb->end; | |
408 | insn = bb->head; | |
409 | while (1) | |
410 | { | |
411 | int uid = INSN_UID (insn); | |
412 | if (uid < max) | |
413 | VARRAY_BB (basic_block_for_insn, uid) = bb; | |
414 | if (insn == end) | |
415 | break; | |
416 | insn = NEXT_INSN (insn); | |
417 | } | |
418 | } | |
419 | } | |
420 | ||
421 | /* Release the basic_block_for_insn array. */ | |
422 | ||
423 | void | |
424 | free_bb_for_insn () | |
425 | { | |
426 | if (basic_block_for_insn) | |
427 | VARRAY_FREE (basic_block_for_insn); | |
428 | basic_block_for_insn = 0; | |
429 | } | |
430 | ||
431 | /* Update insns block within BB. */ | |
432 | ||
433 | void | |
434 | update_bb_for_insn (bb) | |
435 | basic_block bb; | |
436 | { | |
437 | rtx insn; | |
438 | ||
439 | if (! basic_block_for_insn) | |
440 | return; | |
441 | ||
442 | for (insn = bb->head; ; insn = NEXT_INSN (insn)) | |
443 | { | |
444 | set_block_for_insn (insn, bb); | |
445 | ||
446 | if (insn == bb->end) | |
447 | break; | |
448 | } | |
449 | } | |
450 | ||
451 | /* Record INSN's block as BB. */ | |
452 | ||
453 | void | |
454 | set_block_for_insn (insn, bb) | |
455 | rtx insn; | |
456 | basic_block bb; | |
457 | { | |
458 | size_t uid = INSN_UID (insn); | |
459 | if (uid >= basic_block_for_insn->num_elements) | |
460 | { | |
461 | int new_size; | |
462 | ||
463 | /* Add one-eighth the size so we don't keep calling xrealloc. */ | |
464 | new_size = uid + (uid + 7) / 8; | |
465 | ||
466 | VARRAY_GROW (basic_block_for_insn, new_size); | |
467 | } | |
468 | VARRAY_BB (basic_block_for_insn, uid) = bb; | |
469 | } | |
470 | \f | |
471 | /* Split a block BB after insn INSN creating a new fallthru edge. | |
472 | Return the new edge. Note that to keep other parts of the compiler happy, | |
473 | this function renumbers all the basic blocks so that the new | |
474 | one has a number one greater than the block split. */ | |
475 | ||
476 | edge | |
477 | split_block (bb, insn) | |
478 | basic_block bb; | |
479 | rtx insn; | |
480 | { | |
481 | basic_block new_bb; | |
482 | edge new_edge; | |
483 | edge e; | |
484 | ||
485 | /* There is no point splitting the block after its end. */ | |
486 | if (bb->end == insn) | |
487 | return 0; | |
488 | ||
489 | /* Create the new basic block. */ | |
490 | new_bb = create_basic_block (bb->index + 1, NEXT_INSN (insn), bb->end); | |
491 | new_bb->count = bb->count; | |
492 | new_bb->frequency = bb->frequency; | |
493 | new_bb->loop_depth = bb->loop_depth; | |
494 | bb->end = insn; | |
495 | ||
496 | /* Redirect the outgoing edges. */ | |
497 | new_bb->succ = bb->succ; | |
498 | bb->succ = NULL; | |
499 | for (e = new_bb->succ; e; e = e->succ_next) | |
500 | e->src = new_bb; | |
501 | ||
502 | new_edge = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU); | |
503 | ||
504 | if (bb->global_live_at_start) | |
505 | { | |
506 | new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); | |
507 | new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); | |
508 | COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end); | |
509 | ||
510 | /* We now have to calculate which registers are live at the end | |
511 | of the split basic block and at the start of the new basic | |
512 | block. Start with those registers that are known to be live | |
513 | at the end of the original basic block and get | |
514 | propagate_block to determine which registers are live. */ | |
515 | COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end); | |
516 | propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0); | |
517 | COPY_REG_SET (bb->global_live_at_end, | |
518 | new_bb->global_live_at_start); | |
519 | } | |
520 | ||
521 | return new_edge; | |
522 | } | |
523 | ||
524 | /* Blocks A and B are to be merged into a single block A. The insns | |
525 | are already contiguous, hence `nomove'. */ | |
526 | ||
527 | void | |
528 | merge_blocks_nomove (a, b) | |
529 | basic_block a, b; | |
530 | { | |
531 | edge e; | |
532 | rtx b_head, b_end, a_end; | |
533 | rtx del_first = NULL_RTX, del_last = NULL_RTX; | |
534 | int b_empty = 0; | |
535 | ||
536 | /* If there was a CODE_LABEL beginning B, delete it. */ | |
537 | b_head = b->head; | |
538 | b_end = b->end; | |
539 | if (GET_CODE (b_head) == CODE_LABEL) | |
540 | { | |
541 | /* Detect basic blocks with nothing but a label. This can happen | |
542 | in particular at the end of a function. */ | |
543 | if (b_head == b_end) | |
544 | b_empty = 1; | |
545 | del_first = del_last = b_head; | |
546 | b_head = NEXT_INSN (b_head); | |
547 | } | |
548 | ||
549 | /* Delete the basic block note. */ | |
550 | if (NOTE_INSN_BASIC_BLOCK_P (b_head)) | |
551 | { | |
552 | if (b_head == b_end) | |
553 | b_empty = 1; | |
554 | if (! del_last) | |
555 | del_first = b_head; | |
556 | del_last = b_head; | |
557 | b_head = NEXT_INSN (b_head); | |
558 | } | |
559 | ||
560 | /* If there was a jump out of A, delete it. */ | |
561 | a_end = a->end; | |
562 | if (GET_CODE (a_end) == JUMP_INSN) | |
563 | { | |
564 | rtx prev; | |
565 | ||
566 | for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev)) | |
567 | if (GET_CODE (prev) != NOTE | |
568 | || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK | |
569 | || prev == a->head) | |
570 | break; | |
571 | ||
572 | del_first = a_end; | |
573 | ||
574 | #ifdef HAVE_cc0 | |
575 | /* If this was a conditional jump, we need to also delete | |
576 | the insn that set cc0. */ | |
577 | if (only_sets_cc0_p (prev)) | |
578 | { | |
579 | rtx tmp = prev; | |
580 | prev = prev_nonnote_insn (prev); | |
581 | if (!prev) | |
582 | prev = a->head; | |
583 | del_first = tmp; | |
584 | } | |
585 | #endif | |
586 | ||
587 | a_end = PREV_INSN (del_first); | |
588 | } | |
589 | else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER) | |
590 | del_first = NEXT_INSN (a_end); | |
591 | ||
592 | /* Normally there should only be one successor of A and that is B, but | |
593 | partway though the merge of blocks for conditional_execution we'll | |
594 | be merging a TEST block with THEN and ELSE successors. Free the | |
595 | whole lot of them and hope the caller knows what they're doing. */ | |
596 | while (a->succ) | |
597 | remove_edge (a->succ); | |
598 | ||
599 | /* Adjust the edges out of B for the new owner. */ | |
600 | for (e = b->succ; e; e = e->succ_next) | |
601 | e->src = a; | |
602 | a->succ = b->succ; | |
603 | ||
604 | /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */ | |
605 | b->pred = b->succ = NULL; | |
7dddfb65 | 606 | a->global_live_at_end = b->global_live_at_end; |
ca6c03ca JH |
607 | |
608 | expunge_block (b); | |
609 | ||
610 | /* Delete everything marked above as well as crap that might be | |
611 | hanging out between the two blocks. */ | |
612 | delete_insn_chain (del_first, del_last); | |
613 | ||
614 | /* Reassociate the insns of B with A. */ | |
615 | if (!b_empty) | |
616 | { | |
617 | rtx x = a_end; | |
618 | if (basic_block_for_insn) | |
619 | { | |
620 | BLOCK_FOR_INSN (x) = a; | |
621 | while (x != b_end) | |
622 | { | |
623 | x = NEXT_INSN (x); | |
624 | BLOCK_FOR_INSN (x) = a; | |
625 | } | |
626 | } | |
627 | a_end = b_end; | |
628 | } | |
629 | a->end = a_end; | |
630 | } | |
631 | \f | |
632 | /* Return label in the head of basic block. Create one if it doesn't exist. */ | |
633 | ||
634 | rtx | |
635 | block_label (block) | |
636 | basic_block block; | |
637 | { | |
638 | if (block == EXIT_BLOCK_PTR) | |
639 | return NULL_RTX; | |
640 | if (GET_CODE (block->head) != CODE_LABEL) | |
641 | { | |
642 | block->head = emit_label_before (gen_label_rtx (), block->head); | |
643 | if (basic_block_for_insn) | |
644 | set_block_for_insn (block->head, block); | |
645 | } | |
646 | return block->head; | |
647 | } | |
648 | ||
649 | /* Attempt to perform edge redirection by replacing possibly complex jump | |
650 | instruction by unconditional jump or removing jump completely. | |
651 | This can apply only if all edges now point to the same block. | |
652 | ||
653 | The parameters and return values are equivalent to redirect_edge_and_branch. | |
654 | */ | |
655 | ||
656 | static bool | |
657 | try_redirect_by_replacing_jump (e, target) | |
658 | edge e; | |
659 | basic_block target; | |
660 | { | |
661 | basic_block src = e->src; | |
662 | rtx insn = src->end, kill_from; | |
663 | edge tmp; | |
664 | rtx set; | |
665 | int fallthru = 0; | |
666 | ||
667 | /* Verify that all targets will be TARGET. */ | |
668 | for (tmp = src->succ; tmp; tmp = tmp->succ_next) | |
669 | if (tmp->dest != target && tmp != e) | |
670 | break; | |
671 | if (tmp || !onlyjump_p (insn)) | |
672 | return false; | |
673 | ||
674 | /* Avoid removing branch with side effects. */ | |
675 | set = single_set (insn); | |
676 | if (!set || side_effects_p (set)) | |
677 | return false; | |
678 | ||
679 | /* In case we zap a conditional jump, we'll need to kill | |
680 | the cc0 setter too. */ | |
681 | kill_from = insn; | |
682 | #ifdef HAVE_cc0 | |
683 | if (reg_mentioned_p (cc0_rtx, PATTERN (insn))) | |
684 | kill_from = PREV_INSN (insn); | |
685 | #endif | |
686 | ||
687 | /* See if we can create the fallthru edge. */ | |
688 | if (can_fallthru (src, target)) | |
689 | { | |
690 | if (rtl_dump_file) | |
691 | fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn)); | |
692 | fallthru = 1; | |
693 | ||
eaec9b3d | 694 | /* Selectively unlink whole insn chain. */ |
ca6c03ca JH |
695 | delete_insn_chain (kill_from, PREV_INSN (target->head)); |
696 | } | |
697 | /* If this already is simplejump, redirect it. */ | |
698 | else if (simplejump_p (insn)) | |
699 | { | |
700 | if (e->dest == target) | |
701 | return false; | |
702 | if (rtl_dump_file) | |
703 | fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n", | |
704 | INSN_UID (insn), e->dest->index, target->index); | |
705 | redirect_jump (insn, block_label (target), 0); | |
706 | } | |
707 | /* Or replace possibly complicated jump insn by simple jump insn. */ | |
708 | else | |
709 | { | |
710 | rtx target_label = block_label (target); | |
711 | rtx barrier; | |
712 | ||
09eb1aab | 713 | emit_jump_insn_after (gen_jump (target_label), insn); |
ca6c03ca JH |
714 | JUMP_LABEL (src->end) = target_label; |
715 | LABEL_NUSES (target_label)++; | |
716 | if (rtl_dump_file) | |
717 | fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n", | |
718 | INSN_UID (insn), INSN_UID (src->end)); | |
719 | ||
720 | delete_insn_chain (kill_from, insn); | |
721 | ||
722 | barrier = next_nonnote_insn (src->end); | |
723 | if (!barrier || GET_CODE (barrier) != BARRIER) | |
724 | emit_barrier_after (src->end); | |
725 | } | |
726 | ||
727 | /* Keep only one edge out and set proper flags. */ | |
728 | while (src->succ->succ_next) | |
729 | remove_edge (src->succ); | |
730 | e = src->succ; | |
731 | if (fallthru) | |
732 | e->flags = EDGE_FALLTHRU; | |
733 | else | |
734 | e->flags = 0; | |
735 | e->probability = REG_BR_PROB_BASE; | |
736 | e->count = src->count; | |
737 | ||
738 | /* We don't want a block to end on a line-number note since that has | |
739 | the potential of changing the code between -g and not -g. */ | |
740 | while (GET_CODE (e->src->end) == NOTE | |
741 | && NOTE_LINE_NUMBER (e->src->end) >= 0) | |
742 | delete_insn (e->src->end); | |
743 | ||
744 | if (e->dest != target) | |
745 | redirect_edge_succ (e, target); | |
746 | return true; | |
747 | } | |
748 | ||
749 | /* Return last loop_beg note appearing after INSN, before start of next | |
750 | basic block. Return INSN if there are no such notes. | |
751 | ||
eaec9b3d | 752 | When emitting jump to redirect an fallthru edge, it should always |
ca6c03ca | 753 | appear after the LOOP_BEG notes, as loop optimizer expect loop to |
eaec9b3d | 754 | either start by fallthru edge or jump following the LOOP_BEG note |
ca6c03ca JH |
755 | jumping to the loop exit test. */ |
756 | ||
757 | static rtx | |
758 | last_loop_beg_note (insn) | |
759 | rtx insn; | |
760 | { | |
761 | rtx last = insn; | |
762 | insn = NEXT_INSN (insn); | |
763 | while (insn && GET_CODE (insn) == NOTE | |
764 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK) | |
765 | { | |
766 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
767 | last = insn; | |
768 | insn = NEXT_INSN (insn); | |
769 | } | |
770 | return last; | |
771 | } | |
772 | ||
773 | /* Attempt to change code to redirect edge E to TARGET. | |
774 | Don't do that on expense of adding new instructions or reordering | |
775 | basic blocks. | |
776 | ||
eaec9b3d | 777 | Function can be also called with edge destination equivalent to the |
ca6c03ca JH |
778 | TARGET. Then it should try the simplifications and do nothing if |
779 | none is possible. | |
780 | ||
eaec9b3d | 781 | Return true if transformation succeeded. We still return false in case |
ca6c03ca JH |
782 | E already destinated TARGET and we didn't managed to simplify instruction |
783 | stream. */ | |
784 | ||
785 | bool | |
786 | redirect_edge_and_branch (e, target) | |
787 | edge e; | |
788 | basic_block target; | |
789 | { | |
790 | rtx tmp; | |
791 | rtx old_label = e->dest->head; | |
792 | basic_block src = e->src; | |
793 | rtx insn = src->end; | |
794 | ||
25b44be5 | 795 | if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) |
ca6c03ca JH |
796 | return false; |
797 | ||
798 | if (try_redirect_by_replacing_jump (e, target)) | |
799 | return true; | |
800 | /* Do this fast path late, as we want above code to simplify for cases | |
801 | where called on single edge leaving basic block containing nontrivial | |
802 | jump insn. */ | |
803 | else if (e->dest == target) | |
804 | return false; | |
805 | ||
806 | /* We can only redirect non-fallthru edges of jump insn. */ | |
807 | if (e->flags & EDGE_FALLTHRU) | |
808 | return false; | |
809 | if (GET_CODE (insn) != JUMP_INSN) | |
810 | return false; | |
811 | ||
812 | /* Recognize a tablejump and adjust all matching cases. */ | |
813 | if ((tmp = JUMP_LABEL (insn)) != NULL_RTX | |
814 | && (tmp = NEXT_INSN (tmp)) != NULL_RTX | |
815 | && GET_CODE (tmp) == JUMP_INSN | |
816 | && (GET_CODE (PATTERN (tmp)) == ADDR_VEC | |
817 | || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC)) | |
818 | { | |
819 | rtvec vec; | |
820 | int j; | |
821 | rtx new_label = block_label (target); | |
822 | ||
823 | if (GET_CODE (PATTERN (tmp)) == ADDR_VEC) | |
824 | vec = XVEC (PATTERN (tmp), 0); | |
825 | else | |
826 | vec = XVEC (PATTERN (tmp), 1); | |
827 | ||
828 | for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) | |
829 | if (XEXP (RTVEC_ELT (vec, j), 0) == old_label) | |
830 | { | |
831 | RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label); | |
832 | --LABEL_NUSES (old_label); | |
833 | ++LABEL_NUSES (new_label); | |
834 | } | |
835 | ||
836 | /* Handle casesi dispatch insns */ | |
837 | if ((tmp = single_set (insn)) != NULL | |
838 | && SET_DEST (tmp) == pc_rtx | |
839 | && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE | |
840 | && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF | |
841 | && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label) | |
842 | { | |
843 | XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode, | |
844 | new_label); | |
845 | --LABEL_NUSES (old_label); | |
846 | ++LABEL_NUSES (new_label); | |
847 | } | |
848 | } | |
849 | else | |
850 | { | |
851 | /* ?? We may play the games with moving the named labels from | |
852 | one basic block to the other in case only one computed_jump is | |
853 | available. */ | |
854 | if (computed_jump_p (insn)) | |
855 | return false; | |
856 | ||
857 | /* A return instruction can't be redirected. */ | |
858 | if (returnjump_p (insn)) | |
859 | return false; | |
860 | ||
861 | /* If the insn doesn't go where we think, we're confused. */ | |
862 | if (JUMP_LABEL (insn) != old_label) | |
863 | abort (); | |
a3623c48 RH |
864 | /* If the substitution doesn't succeed, die. This can happen |
865 | if the back end emitted unrecognizable instructions. */ | |
866 | if (! redirect_jump (insn, block_label (target), 0)) | |
867 | abort (); | |
ca6c03ca JH |
868 | } |
869 | ||
870 | if (rtl_dump_file) | |
871 | fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n", | |
872 | e->src->index, e->dest->index, target->index); | |
873 | if (e->dest != target) | |
874 | redirect_edge_succ_nodup (e, target); | |
875 | return true; | |
876 | } | |
877 | ||
4fe9b91c | 878 | /* Like force_nonfallthru below, but additionally performs redirection |
ca6c03ca JH |
879 | Used by redirect_edge_and_branch_force. */ |
880 | ||
881 | static basic_block | |
882 | force_nonfallthru_and_redirect (e, target) | |
883 | edge e; | |
884 | basic_block target; | |
885 | { | |
886 | basic_block jump_block, new_bb = NULL; | |
887 | rtx note; | |
888 | edge new_edge; | |
889 | ||
890 | if (e->flags & EDGE_ABNORMAL) | |
891 | abort (); | |
892 | if (!(e->flags & EDGE_FALLTHRU)) | |
893 | abort (); | |
894 | if (e->src->succ->succ_next) | |
895 | { | |
896 | /* Create the new structures. */ | |
897 | note = last_loop_beg_note (e->src->end); | |
898 | jump_block = create_basic_block (e->src->index + 1, NEXT_INSN (note), NULL); | |
899 | jump_block->count = e->count; | |
900 | jump_block->frequency = EDGE_FREQUENCY (e); | |
901 | jump_block->loop_depth = target->loop_depth; | |
902 | ||
903 | if (target->global_live_at_start) | |
904 | { | |
905 | jump_block->global_live_at_start = | |
906 | OBSTACK_ALLOC_REG_SET (&flow_obstack); | |
907 | jump_block->global_live_at_end = | |
908 | OBSTACK_ALLOC_REG_SET (&flow_obstack); | |
909 | COPY_REG_SET (jump_block->global_live_at_start, | |
910 | target->global_live_at_start); | |
911 | COPY_REG_SET (jump_block->global_live_at_end, | |
912 | target->global_live_at_start); | |
913 | } | |
914 | ||
915 | /* Wire edge in. */ | |
916 | new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU); | |
917 | new_edge->probability = e->probability; | |
918 | new_edge->count = e->count; | |
919 | ||
920 | /* Redirect old edge. */ | |
921 | redirect_edge_pred (e, jump_block); | |
922 | e->probability = REG_BR_PROB_BASE; | |
923 | ||
924 | new_bb = jump_block; | |
925 | } | |
926 | else | |
927 | jump_block = e->src; | |
928 | e->flags &= ~EDGE_FALLTHRU; | |
929 | if (target == EXIT_BLOCK_PTR) | |
930 | { | |
931 | if (HAVE_return) | |
932 | emit_jump_insn_after (gen_return (), jump_block->end); | |
933 | else | |
934 | abort (); | |
935 | } | |
936 | else | |
937 | { | |
938 | rtx label = block_label (target); | |
939 | emit_jump_insn_after (gen_jump (label), jump_block->end); | |
940 | JUMP_LABEL (jump_block->end) = label; | |
941 | LABEL_NUSES (label)++; | |
942 | } | |
943 | emit_barrier_after (jump_block->end); | |
944 | redirect_edge_succ_nodup (e, target); | |
945 | ||
946 | return new_bb; | |
947 | } | |
948 | ||
949 | /* Edge E is assumed to be fallthru edge. Emit needed jump instruction | |
950 | (and possibly create new basic block) to make edge non-fallthru. | |
951 | Return newly created BB or NULL if none. */ | |
952 | basic_block | |
953 | force_nonfallthru (e) | |
954 | edge e; | |
955 | { | |
956 | return force_nonfallthru_and_redirect (e, e->dest); | |
957 | } | |
958 | ||
959 | /* Redirect edge even at the expense of creating new jump insn or | |
960 | basic block. Return new basic block if created, NULL otherwise. | |
eaec9b3d | 961 | Abort if conversion is impossible. */ |
ca6c03ca JH |
962 | |
963 | basic_block | |
964 | redirect_edge_and_branch_force (e, target) | |
965 | edge e; | |
966 | basic_block target; | |
967 | { | |
968 | basic_block new_bb; | |
969 | ||
970 | if (redirect_edge_and_branch (e, target)) | |
971 | return NULL; | |
972 | if (e->dest == target) | |
973 | return NULL; | |
974 | ||
975 | /* In case the edge redirection failed, try to force it to be non-fallthru | |
976 | and redirect newly created simplejump. */ | |
977 | new_bb = force_nonfallthru_and_redirect (e, target); | |
978 | return new_bb; | |
979 | } | |
980 | ||
981 | /* The given edge should potentially be a fallthru edge. If that is in | |
982 | fact true, delete the jump and barriers that are in the way. */ | |
983 | ||
984 | void | |
985 | tidy_fallthru_edge (e, b, c) | |
986 | edge e; | |
987 | basic_block b, c; | |
988 | { | |
989 | rtx q; | |
990 | ||
991 | /* ??? In a late-running flow pass, other folks may have deleted basic | |
992 | blocks by nopping out blocks, leaving multiple BARRIERs between here | |
993 | and the target label. They ought to be chastized and fixed. | |
994 | ||
995 | We can also wind up with a sequence of undeletable labels between | |
996 | one block and the next. | |
997 | ||
998 | So search through a sequence of barriers, labels, and notes for | |
999 | the head of block C and assert that we really do fall through. */ | |
1000 | ||
1001 | if (next_real_insn (b->end) != next_real_insn (PREV_INSN (c->head))) | |
1002 | return; | |
1003 | ||
1004 | /* Remove what will soon cease being the jump insn from the source block. | |
1005 | If block B consisted only of this single jump, turn it into a deleted | |
1006 | note. */ | |
1007 | q = b->end; | |
1008 | if (GET_CODE (q) == JUMP_INSN | |
1009 | && onlyjump_p (q) | |
1010 | && (any_uncondjump_p (q) | |
1011 | || (b->succ == e && e->succ_next == NULL))) | |
1012 | { | |
1013 | #ifdef HAVE_cc0 | |
1014 | /* If this was a conditional jump, we need to also delete | |
1015 | the insn that set cc0. */ | |
1016 | if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q))) | |
1017 | q = PREV_INSN (q); | |
1018 | #endif | |
1019 | ||
1020 | q = PREV_INSN (q); | |
1021 | ||
1022 | /* We don't want a block to end on a line-number note since that has | |
1023 | the potential of changing the code between -g and not -g. */ | |
1024 | while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0) | |
1025 | q = PREV_INSN (q); | |
1026 | } | |
1027 | ||
1028 | /* Selectively unlink the sequence. */ | |
1029 | if (q != PREV_INSN (c->head)) | |
1030 | delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head)); | |
1031 | ||
1032 | e->flags |= EDGE_FALLTHRU; | |
1033 | } | |
1034 | ||
1035 | /* Fix up edges that now fall through, or rather should now fall through | |
1036 | but previously required a jump around now deleted blocks. Simplify | |
1037 | the search by only examining blocks numerically adjacent, since this | |
1038 | is how find_basic_blocks created them. */ | |
1039 | ||
1040 | void | |
1041 | tidy_fallthru_edges () | |
1042 | { | |
1043 | int i; | |
1044 | ||
1045 | for (i = 1; i < n_basic_blocks; ++i) | |
1046 | { | |
1047 | basic_block b = BASIC_BLOCK (i - 1); | |
1048 | basic_block c = BASIC_BLOCK (i); | |
1049 | edge s; | |
1050 | ||
1051 | /* We care about simple conditional or unconditional jumps with | |
1052 | a single successor. | |
1053 | ||
1054 | If we had a conditional branch to the next instruction when | |
1055 | find_basic_blocks was called, then there will only be one | |
1056 | out edge for the block which ended with the conditional | |
1057 | branch (since we do not create duplicate edges). | |
1058 | ||
1059 | Furthermore, the edge will be marked as a fallthru because we | |
1060 | merge the flags for the duplicate edges. So we do not want to | |
1061 | check that the edge is not a FALLTHRU edge. */ | |
1062 | if ((s = b->succ) != NULL | |
1063 | && ! (s->flags & EDGE_COMPLEX) | |
1064 | && s->succ_next == NULL | |
1065 | && s->dest == c | |
1066 | /* If the jump insn has side effects, we can't tidy the edge. */ | |
1067 | && (GET_CODE (b->end) != JUMP_INSN | |
1068 | || onlyjump_p (b->end))) | |
1069 | tidy_fallthru_edge (s, b, c); | |
1070 | } | |
1071 | } | |
1072 | \f | |
1073 | /* Helper function for split_edge. Return true in case edge BB2 to BB1 | |
1074 | is back edge of syntactic loop. */ | |
1075 | ||
1076 | static bool | |
1077 | back_edge_of_syntactic_loop_p (bb1, bb2) | |
1078 | basic_block bb1, bb2; | |
1079 | { | |
1080 | rtx insn; | |
1081 | int count = 0; | |
1082 | ||
1083 | if (bb1->index > bb2->index) | |
1084 | return false; | |
1085 | ||
1086 | if (bb1->index == bb2->index) | |
1087 | return true; | |
1088 | ||
1089 | for (insn = bb1->end; insn != bb2->head && count >= 0; | |
1090 | insn = NEXT_INSN (insn)) | |
1091 | if (GET_CODE (insn) == NOTE) | |
1092 | { | |
1093 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
1094 | count++; | |
1095 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) | |
1096 | count--; | |
1097 | } | |
1098 | ||
1099 | return count >= 0; | |
1100 | } | |
1101 | ||
1102 | /* Split a (typically critical) edge. Return the new block. | |
1103 | Abort on abnormal edges. | |
1104 | ||
1105 | ??? The code generally expects to be called on critical edges. | |
1106 | The case of a block ending in an unconditional jump to a | |
1107 | block with multiple predecessors is not handled optimally. */ | |
1108 | ||
1109 | basic_block | |
1110 | split_edge (edge_in) | |
1111 | edge edge_in; | |
1112 | { | |
1113 | basic_block bb; | |
1114 | edge edge_out; | |
1115 | rtx before; | |
1116 | ||
1117 | /* Abnormal edges cannot be split. */ | |
1118 | if ((edge_in->flags & EDGE_ABNORMAL) != 0) | |
1119 | abort (); | |
1120 | ||
1121 | /* We are going to place the new block in front of edge destination. | |
eaec9b3d | 1122 | Avoid existence of fallthru predecessors. */ |
ca6c03ca JH |
1123 | if ((edge_in->flags & EDGE_FALLTHRU) == 0) |
1124 | { | |
1125 | edge e; | |
1126 | for (e = edge_in->dest->pred; e; e = e->pred_next) | |
1127 | if (e->flags & EDGE_FALLTHRU) | |
1128 | break; | |
1129 | ||
1130 | if (e) | |
1131 | force_nonfallthru (e); | |
1132 | } | |
1133 | ||
1134 | /* Create the basic block note. | |
1135 | ||
f63d1bf7 | 1136 | Where we place the note can have a noticeable impact on the generated |
ca6c03ca JH |
1137 | code. Consider this cfg: |
1138 | ||
1139 | E | |
1140 | | | |
1141 | 0 | |
1142 | / \ | |
1143 | +->1-->2--->E | |
1144 | | | | |
1145 | +--+ | |
1146 | ||
1147 | If we need to insert an insn on the edge from block 0 to block 1, | |
1148 | we want to ensure the instructions we insert are outside of any | |
1149 | loop notes that physically sit between block 0 and block 1. Otherwise | |
1150 | we confuse the loop optimizer into thinking the loop is a phony. */ | |
1151 | ||
1152 | if (edge_in->dest != EXIT_BLOCK_PTR | |
1153 | && PREV_INSN (edge_in->dest->head) | |
1154 | && GET_CODE (PREV_INSN (edge_in->dest->head)) == NOTE | |
1155 | && NOTE_LINE_NUMBER (PREV_INSN (edge_in->dest->head)) == NOTE_INSN_LOOP_BEG | |
1156 | && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src)) | |
1157 | before = PREV_INSN (edge_in->dest->head); | |
1158 | else if (edge_in->dest != EXIT_BLOCK_PTR) | |
1159 | before = edge_in->dest->head; | |
1160 | else | |
1161 | before = NULL_RTX; | |
1162 | ||
1163 | bb = create_basic_block (edge_in->dest == EXIT_BLOCK_PTR ? n_basic_blocks | |
1164 | : edge_in->dest->index, before, NULL); | |
1165 | bb->count = edge_in->count; | |
1166 | bb->frequency = EDGE_FREQUENCY (edge_in); | |
1167 | ||
1168 | /* ??? This info is likely going to be out of date very soon. */ | |
1169 | if (edge_in->dest->global_live_at_start) | |
1170 | { | |
1171 | bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack); | |
1172 | bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack); | |
1173 | COPY_REG_SET (bb->global_live_at_start, edge_in->dest->global_live_at_start); | |
1174 | COPY_REG_SET (bb->global_live_at_end, edge_in->dest->global_live_at_start); | |
1175 | } | |
1176 | ||
1177 | edge_out = make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU); | |
1178 | ||
1179 | /* For non-fallthry edges, we must adjust the predecessor's | |
1180 | jump instruction to target our new block. */ | |
1181 | if ((edge_in->flags & EDGE_FALLTHRU) == 0) | |
1182 | { | |
1183 | if (!redirect_edge_and_branch (edge_in, bb)) | |
1184 | abort (); | |
1185 | } | |
1186 | else | |
1187 | redirect_edge_succ (edge_in, bb); | |
1188 | ||
1189 | return bb; | |
1190 | } | |
1191 | ||
1192 | /* Queue instructions for insertion on an edge between two basic blocks. | |
1193 | The new instructions and basic blocks (if any) will not appear in the | |
1194 | CFG until commit_edge_insertions is called. */ | |
1195 | ||
1196 | void | |
1197 | insert_insn_on_edge (pattern, e) | |
1198 | rtx pattern; | |
1199 | edge e; | |
1200 | { | |
1201 | /* We cannot insert instructions on an abnormal critical edge. | |
1202 | It will be easier to find the culprit if we die now. */ | |
1203 | if ((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)) | |
1204 | abort (); | |
1205 | ||
1206 | if (e->insns == NULL_RTX) | |
1207 | start_sequence (); | |
1208 | else | |
1209 | push_to_sequence (e->insns); | |
1210 | ||
1211 | emit_insn (pattern); | |
1212 | ||
1213 | e->insns = get_insns (); | |
1214 | end_sequence (); | |
1215 | } | |
1216 | ||
1217 | /* Update the CFG for the instructions queued on edge E. */ | |
1218 | ||
1219 | static void | |
1220 | commit_one_edge_insertion (e) | |
1221 | edge e; | |
1222 | { | |
1223 | rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last; | |
1224 | basic_block bb; | |
1225 | ||
1226 | /* Pull the insns off the edge now since the edge might go away. */ | |
1227 | insns = e->insns; | |
1228 | e->insns = NULL_RTX; | |
1229 | ||
1230 | /* Figure out where to put these things. If the destination has | |
1231 | one predecessor, insert there. Except for the exit block. */ | |
1232 | if (e->dest->pred->pred_next == NULL | |
1233 | && e->dest != EXIT_BLOCK_PTR) | |
1234 | { | |
1235 | bb = e->dest; | |
1236 | ||
1237 | /* Get the location correct wrt a code label, and "nice" wrt | |
1238 | a basic block note, and before everything else. */ | |
1239 | tmp = bb->head; | |
1240 | if (GET_CODE (tmp) == CODE_LABEL) | |
1241 | tmp = NEXT_INSN (tmp); | |
1242 | if (NOTE_INSN_BASIC_BLOCK_P (tmp)) | |
1243 | tmp = NEXT_INSN (tmp); | |
1244 | if (tmp == bb->head) | |
1245 | before = tmp; | |
1246 | else | |
1247 | after = PREV_INSN (tmp); | |
1248 | } | |
1249 | ||
1250 | /* If the source has one successor and the edge is not abnormal, | |
1251 | insert there. Except for the entry block. */ | |
1252 | else if ((e->flags & EDGE_ABNORMAL) == 0 | |
1253 | && e->src->succ->succ_next == NULL | |
1254 | && e->src != ENTRY_BLOCK_PTR) | |
1255 | { | |
1256 | bb = e->src; | |
1257 | /* It is possible to have a non-simple jump here. Consider a target | |
1258 | where some forms of unconditional jumps clobber a register. This | |
1259 | happens on the fr30 for example. | |
1260 | ||
1261 | We know this block has a single successor, so we can just emit | |
1262 | the queued insns before the jump. */ | |
1263 | if (GET_CODE (bb->end) == JUMP_INSN) | |
1264 | { | |
1265 | before = bb->end; | |
1266 | while (GET_CODE (PREV_INSN (before)) == NOTE | |
1267 | && NOTE_LINE_NUMBER (PREV_INSN (before)) == NOTE_INSN_LOOP_BEG) | |
1268 | before = PREV_INSN (before); | |
1269 | } | |
1270 | else | |
1271 | { | |
1272 | /* We'd better be fallthru, or we've lost track of what's what. */ | |
1273 | if ((e->flags & EDGE_FALLTHRU) == 0) | |
1274 | abort (); | |
1275 | ||
1276 | after = bb->end; | |
1277 | } | |
1278 | } | |
1279 | ||
1280 | /* Otherwise we must split the edge. */ | |
1281 | else | |
1282 | { | |
1283 | bb = split_edge (e); | |
1284 | after = bb->end; | |
1285 | } | |
1286 | ||
1287 | /* Now that we've found the spot, do the insertion. */ | |
1288 | ||
1289 | if (before) | |
1290 | { | |
1291 | emit_insns_before (insns, before); | |
1292 | last = prev_nonnote_insn (before); | |
1293 | } | |
1294 | else | |
1295 | last = emit_insns_after (insns, after); | |
1296 | ||
1297 | if (returnjump_p (last)) | |
1298 | { | |
1299 | /* ??? Remove all outgoing edges from BB and add one for EXIT. | |
1300 | This is not currently a problem because this only happens | |
1301 | for the (single) epilogue, which already has a fallthru edge | |
1302 | to EXIT. */ | |
1303 | ||
1304 | e = bb->succ; | |
1305 | if (e->dest != EXIT_BLOCK_PTR | |
1306 | || e->succ_next != NULL | |
1307 | || (e->flags & EDGE_FALLTHRU) == 0) | |
1308 | abort (); | |
1309 | e->flags &= ~EDGE_FALLTHRU; | |
1310 | ||
1311 | emit_barrier_after (last); | |
1312 | ||
1313 | if (before) | |
1314 | delete_insn (before); | |
1315 | } | |
1316 | else if (GET_CODE (last) == JUMP_INSN) | |
1317 | abort (); | |
1318 | find_sub_basic_blocks (bb); | |
1319 | } | |
1320 | ||
1321 | /* Update the CFG for all queued instructions. */ | |
1322 | ||
1323 | void | |
1324 | commit_edge_insertions () | |
1325 | { | |
1326 | int i; | |
1327 | basic_block bb; | |
1328 | ||
1329 | #ifdef ENABLE_CHECKING | |
1330 | verify_flow_info (); | |
1331 | #endif | |
1332 | ||
1333 | i = -1; | |
1334 | bb = ENTRY_BLOCK_PTR; | |
1335 | while (1) | |
1336 | { | |
1337 | edge e, next; | |
1338 | ||
1339 | for (e = bb->succ; e; e = next) | |
1340 | { | |
1341 | next = e->succ_next; | |
1342 | if (e->insns) | |
1343 | commit_one_edge_insertion (e); | |
1344 | } | |
1345 | ||
1346 | if (++i >= n_basic_blocks) | |
1347 | break; | |
1348 | bb = BASIC_BLOCK (i); | |
1349 | } | |
1350 | } | |
1351 | \f | |
1352 | /* Print out one basic block with live information at start and end. */ | |
1353 | ||
1354 | void | |
1355 | dump_bb (bb, outf) | |
1356 | basic_block bb; | |
1357 | FILE *outf; | |
1358 | { | |
1359 | rtx insn; | |
1360 | rtx last; | |
1361 | edge e; | |
1362 | ||
1363 | fprintf (outf, ";; Basic block %d, loop depth %d, count ", | |
1364 | bb->index, bb->loop_depth); | |
1365 | fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count); | |
1366 | putc ('\n', outf); | |
1367 | ||
1368 | fputs (";; Predecessors: ", outf); | |
1369 | for (e = bb->pred; e; e = e->pred_next) | |
1370 | dump_edge_info (outf, e, 0); | |
1371 | putc ('\n', outf); | |
1372 | ||
1373 | fputs (";; Registers live at start:", outf); | |
1374 | dump_regset (bb->global_live_at_start, outf); | |
1375 | putc ('\n', outf); | |
1376 | ||
1377 | for (insn = bb->head, last = NEXT_INSN (bb->end); | |
1378 | insn != last; | |
1379 | insn = NEXT_INSN (insn)) | |
1380 | print_rtl_single (outf, insn); | |
1381 | ||
1382 | fputs (";; Registers live at end:", outf); | |
1383 | dump_regset (bb->global_live_at_end, outf); | |
1384 | putc ('\n', outf); | |
1385 | ||
1386 | fputs (";; Successors: ", outf); | |
1387 | for (e = bb->succ; e; e = e->succ_next) | |
1388 | dump_edge_info (outf, e, 1); | |
1389 | putc ('\n', outf); | |
1390 | } | |
1391 | ||
1392 | void | |
1393 | debug_bb (bb) | |
1394 | basic_block bb; | |
1395 | { | |
1396 | dump_bb (bb, stderr); | |
1397 | } | |
1398 | ||
1399 | void | |
1400 | debug_bb_n (n) | |
1401 | int n; | |
1402 | { | |
1403 | dump_bb (BASIC_BLOCK (n), stderr); | |
1404 | } | |
1405 | \f | |
1406 | /* Like print_rtl, but also print out live information for the start of each | |
1407 | basic block. */ | |
1408 | ||
1409 | void | |
1410 | print_rtl_with_bb (outf, rtx_first) | |
1411 | FILE *outf; | |
1412 | rtx rtx_first; | |
1413 | { | |
b3694847 | 1414 | rtx tmp_rtx; |
ca6c03ca JH |
1415 | |
1416 | if (rtx_first == 0) | |
1417 | fprintf (outf, "(nil)\n"); | |
1418 | else | |
1419 | { | |
1420 | int i; | |
1421 | enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB }; | |
1422 | int max_uid = get_max_uid (); | |
1423 | basic_block *start = (basic_block *) | |
1424 | xcalloc (max_uid, sizeof (basic_block)); | |
1425 | basic_block *end = (basic_block *) | |
1426 | xcalloc (max_uid, sizeof (basic_block)); | |
1427 | enum bb_state *in_bb_p = (enum bb_state *) | |
1428 | xcalloc (max_uid, sizeof (enum bb_state)); | |
1429 | ||
1430 | for (i = n_basic_blocks - 1; i >= 0; i--) | |
1431 | { | |
1432 | basic_block bb = BASIC_BLOCK (i); | |
1433 | rtx x; | |
1434 | ||
1435 | start[INSN_UID (bb->head)] = bb; | |
1436 | end[INSN_UID (bb->end)] = bb; | |
1437 | for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x)) | |
1438 | { | |
1439 | enum bb_state state = IN_MULTIPLE_BB; | |
1440 | if (in_bb_p[INSN_UID (x)] == NOT_IN_BB) | |
1441 | state = IN_ONE_BB; | |
1442 | in_bb_p[INSN_UID (x)] = state; | |
1443 | ||
1444 | if (x == bb->end) | |
1445 | break; | |
1446 | } | |
1447 | } | |
1448 | ||
1449 | for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx)) | |
1450 | { | |
1451 | int did_output; | |
1452 | basic_block bb; | |
1453 | ||
1454 | if ((bb = start[INSN_UID (tmp_rtx)]) != NULL) | |
1455 | { | |
1456 | fprintf (outf, ";; Start of basic block %d, registers live:", | |
1457 | bb->index); | |
1458 | dump_regset (bb->global_live_at_start, outf); | |
1459 | putc ('\n', outf); | |
1460 | } | |
1461 | ||
1462 | if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB | |
1463 | && GET_CODE (tmp_rtx) != NOTE | |
1464 | && GET_CODE (tmp_rtx) != BARRIER) | |
1465 | fprintf (outf, ";; Insn is not within a basic block\n"); | |
1466 | else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB) | |
1467 | fprintf (outf, ";; Insn is in multiple basic blocks\n"); | |
1468 | ||
1469 | did_output = print_rtl_single (outf, tmp_rtx); | |
1470 | ||
1471 | if ((bb = end[INSN_UID (tmp_rtx)]) != NULL) | |
1472 | { | |
1473 | fprintf (outf, ";; End of basic block %d, registers live:\n", | |
1474 | bb->index); | |
1475 | dump_regset (bb->global_live_at_end, outf); | |
1476 | putc ('\n', outf); | |
1477 | } | |
1478 | ||
1479 | if (did_output) | |
1480 | putc ('\n', outf); | |
1481 | } | |
1482 | ||
1483 | free (start); | |
1484 | free (end); | |
1485 | free (in_bb_p); | |
1486 | } | |
1487 | ||
1488 | if (current_function_epilogue_delay_list != 0) | |
1489 | { | |
1490 | fprintf (outf, "\n;; Insns in epilogue delay list:\n\n"); | |
1491 | for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0; | |
1492 | tmp_rtx = XEXP (tmp_rtx, 1)) | |
1493 | print_rtl_single (outf, XEXP (tmp_rtx, 0)); | |
1494 | } | |
1495 | } | |
1496 | \f | |
1497 | /* Verify the CFG consistency. This function check some CFG invariants and | |
1498 | aborts when something is wrong. Hope that this function will help to | |
1499 | convert many optimization passes to preserve CFG consistent. | |
1500 | ||
1501 | Currently it does following checks: | |
1502 | ||
1503 | - test head/end pointers | |
1504 | - overlapping of basic blocks | |
1505 | - edge list correctness | |
1506 | - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note) | |
f63d1bf7 | 1507 | - tails of basic blocks (ensure that boundary is necessary) |
ca6c03ca JH |
1508 | - scans body of the basic block for JUMP_INSN, CODE_LABEL |
1509 | and NOTE_INSN_BASIC_BLOCK | |
1510 | - check that all insns are in the basic blocks | |
1511 | (except the switch handling code, barriers and notes) | |
1512 | - check that all returns are followed by barriers | |
1513 | ||
1514 | In future it can be extended check a lot of other stuff as well | |
1515 | (reachability of basic blocks, life information, etc. etc.). */ | |
1516 | ||
1517 | void | |
1518 | verify_flow_info () | |
1519 | { | |
1520 | const int max_uid = get_max_uid (); | |
1521 | const rtx rtx_first = get_insns (); | |
1522 | rtx last_head = get_last_insn (); | |
1523 | basic_block *bb_info, *last_visited; | |
1524 | size_t *edge_checksum; | |
1525 | rtx x; | |
1526 | int i, last_bb_num_seen, num_bb_notes, err = 0; | |
1527 | ||
1528 | bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block)); | |
1529 | last_visited = (basic_block *) xcalloc (n_basic_blocks + 2, | |
1530 | sizeof (basic_block)); | |
1531 | edge_checksum = (size_t *) xcalloc (n_basic_blocks + 2, sizeof (size_t)); | |
1532 | ||
1533 | for (i = n_basic_blocks - 1; i >= 0; i--) | |
1534 | { | |
1535 | basic_block bb = BASIC_BLOCK (i); | |
1536 | rtx head = bb->head; | |
1537 | rtx end = bb->end; | |
1538 | ||
1539 | /* Verify the end of the basic block is in the INSN chain. */ | |
1540 | for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) | |
1541 | if (x == end) | |
1542 | break; | |
1543 | if (!x) | |
1544 | { | |
1f978f5f | 1545 | error ("end insn %d for block %d not found in the insn stream", |
ca6c03ca JH |
1546 | INSN_UID (end), bb->index); |
1547 | err = 1; | |
1548 | } | |
1549 | ||
1550 | /* Work backwards from the end to the head of the basic block | |
1551 | to verify the head is in the RTL chain. */ | |
1552 | for (; x != NULL_RTX; x = PREV_INSN (x)) | |
1553 | { | |
1554 | /* While walking over the insn chain, verify insns appear | |
1555 | in only one basic block and initialize the BB_INFO array | |
1556 | used by other passes. */ | |
1557 | if (bb_info[INSN_UID (x)] != NULL) | |
1558 | { | |
1f978f5f | 1559 | error ("insn %d is in multiple basic blocks (%d and %d)", |
ca6c03ca JH |
1560 | INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index); |
1561 | err = 1; | |
1562 | } | |
1563 | bb_info[INSN_UID (x)] = bb; | |
1564 | ||
1565 | if (x == head) | |
1566 | break; | |
1567 | } | |
1568 | if (!x) | |
1569 | { | |
1f978f5f | 1570 | error ("head insn %d for block %d not found in the insn stream", |
ca6c03ca JH |
1571 | INSN_UID (head), bb->index); |
1572 | err = 1; | |
1573 | } | |
1574 | ||
1575 | last_head = x; | |
1576 | } | |
1577 | ||
1578 | /* Now check the basic blocks (boundaries etc.) */ | |
1579 | for (i = n_basic_blocks - 1; i >= 0; i--) | |
1580 | { | |
1581 | basic_block bb = BASIC_BLOCK (i); | |
1582 | int has_fallthru = 0; | |
1583 | edge e; | |
1584 | ||
1585 | e = bb->succ; | |
1586 | while (e) | |
1587 | { | |
1588 | if (last_visited [e->dest->index + 2] == bb) | |
1589 | { | |
1590 | error ("verify_flow_info: Duplicate edge %i->%i", | |
1591 | e->src->index, e->dest->index); | |
1592 | err = 1; | |
1593 | } | |
1594 | last_visited [e->dest->index + 2] = bb; | |
1595 | ||
1596 | if (e->flags & EDGE_FALLTHRU) | |
1597 | has_fallthru = 1; | |
1598 | ||
1599 | if ((e->flags & EDGE_FALLTHRU) | |
1600 | && e->src != ENTRY_BLOCK_PTR | |
1601 | && e->dest != EXIT_BLOCK_PTR) | |
1602 | { | |
1603 | rtx insn; | |
1604 | if (e->src->index + 1 != e->dest->index) | |
1605 | { | |
1606 | error ("verify_flow_info: Incorrect blocks for fallthru %i->%i", | |
1607 | e->src->index, e->dest->index); | |
1608 | err = 1; | |
1609 | } | |
1610 | else | |
1611 | for (insn = NEXT_INSN (e->src->end); insn != e->dest->head; | |
1612 | insn = NEXT_INSN (insn)) | |
32a6f30e JDA |
1613 | if (GET_CODE (insn) == BARRIER |
1614 | #ifndef CASE_DROPS_THROUGH | |
1615 | || INSN_P (insn)) | |
1616 | #else | |
1617 | || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))) | |
1618 | #endif | |
ca6c03ca JH |
1619 | { |
1620 | error ("verify_flow_info: Incorrect fallthru %i->%i", | |
1621 | e->src->index, e->dest->index); | |
1f978f5f | 1622 | fatal_insn ("wrong insn in the fallthru edge", insn); |
ca6c03ca JH |
1623 | err = 1; |
1624 | } | |
1625 | } | |
1626 | if (e->src != bb) | |
1627 | { | |
1628 | error ("verify_flow_info: Basic block %d succ edge is corrupted", | |
1629 | bb->index); | |
1630 | fprintf (stderr, "Predecessor: "); | |
1631 | dump_edge_info (stderr, e, 0); | |
1632 | fprintf (stderr, "\nSuccessor: "); | |
1633 | dump_edge_info (stderr, e, 1); | |
1634 | fprintf (stderr, "\n"); | |
1635 | err = 1; | |
1636 | } | |
1637 | edge_checksum[e->dest->index + 2] += (size_t) e; | |
1638 | e = e->succ_next; | |
1639 | } | |
1640 | if (!has_fallthru) | |
1641 | { | |
09eb1aab | 1642 | rtx insn; |
ca6c03ca JH |
1643 | |
1644 | /* Ensure existence of barrier in BB with no fallthru edges. */ | |
09eb1aab | 1645 | for (insn = bb->end; !insn || GET_CODE (insn) != BARRIER; |
ca6c03ca JH |
1646 | insn = NEXT_INSN (insn)) |
1647 | if (!insn | |
1648 | || (GET_CODE (insn) == NOTE | |
1649 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK)) | |
1650 | { | |
1f978f5f | 1651 | error ("missing barrier after block %i", bb->index); |
ca6c03ca | 1652 | err = 1; |
09eb1aab | 1653 | break; |
ca6c03ca JH |
1654 | } |
1655 | } | |
1656 | ||
1657 | e = bb->pred; | |
1658 | while (e) | |
1659 | { | |
1660 | if (e->dest != bb) | |
1661 | { | |
1f978f5f | 1662 | error ("basic block %d pred edge is corrupted", bb->index); |
ca6c03ca JH |
1663 | fputs ("Predecessor: ", stderr); |
1664 | dump_edge_info (stderr, e, 0); | |
1665 | fputs ("\nSuccessor: ", stderr); | |
1666 | dump_edge_info (stderr, e, 1); | |
1667 | fputc ('\n', stderr); | |
1668 | err = 1; | |
1669 | } | |
1670 | edge_checksum[e->dest->index + 2] -= (size_t) e; | |
1671 | e = e->pred_next; | |
1672 | } | |
1673 | for (x = bb->head; x != NEXT_INSN (bb->end); x = NEXT_INSN (x)) | |
1674 | if (basic_block_for_insn && BLOCK_FOR_INSN (x) != bb) | |
1675 | { | |
1676 | debug_rtx (x); | |
1677 | if (! BLOCK_FOR_INSN (x)) | |
1f978f5f | 1678 | error ("insn %d is inside basic block %d but block_for_insn is NULL", |
ca6c03ca JH |
1679 | INSN_UID (x), bb->index); |
1680 | else | |
1f978f5f | 1681 | error ("insn %d is inside basic block %d but block_for_insn is %i", |
ca6c03ca JH |
1682 | INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index); |
1683 | err = 1; | |
1684 | } | |
1685 | ||
1686 | /* OK pointers are correct. Now check the header of basic | |
1687 | block. It ought to contain optional CODE_LABEL followed | |
1688 | by NOTE_BASIC_BLOCK. */ | |
1689 | x = bb->head; | |
1690 | if (GET_CODE (x) == CODE_LABEL) | |
1691 | { | |
1692 | if (bb->end == x) | |
1693 | { | |
1694 | error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", | |
1695 | bb->index); | |
1696 | err = 1; | |
1697 | } | |
1698 | x = NEXT_INSN (x); | |
1699 | } | |
1700 | if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb) | |
1701 | { | |
1702 | error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", | |
1703 | bb->index); | |
1704 | err = 1; | |
1705 | } | |
1706 | ||
1707 | if (bb->end == x) | |
1708 | { | |
1709 | /* Do checks for empty blocks here */ | |
1710 | } | |
1711 | else | |
1712 | { | |
1713 | x = NEXT_INSN (x); | |
1714 | while (x) | |
1715 | { | |
1716 | if (NOTE_INSN_BASIC_BLOCK_P (x)) | |
1717 | { | |
1718 | error ("NOTE_INSN_BASIC_BLOCK %d in the middle of basic block %d", | |
1719 | INSN_UID (x), bb->index); | |
1720 | err = 1; | |
1721 | } | |
1722 | ||
1723 | if (x == bb->end) | |
1724 | break; | |
1725 | ||
1726 | if (GET_CODE (x) == JUMP_INSN | |
1727 | || GET_CODE (x) == CODE_LABEL | |
1728 | || GET_CODE (x) == BARRIER) | |
1729 | { | |
1f978f5f NB |
1730 | error ("in basic block %d:", bb->index); |
1731 | fatal_insn ("flow control insn inside a basic block", x); | |
ca6c03ca JH |
1732 | } |
1733 | ||
1734 | x = NEXT_INSN (x); | |
1735 | } | |
1736 | } | |
1737 | } | |
1738 | ||
1739 | /* Complete edge checksumming for ENTRY and EXIT. */ | |
1740 | { | |
1741 | edge e; | |
1742 | for (e = ENTRY_BLOCK_PTR->succ; e ; e = e->succ_next) | |
1743 | edge_checksum[e->dest->index + 2] += (size_t) e; | |
1744 | for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next) | |
1745 | edge_checksum[e->dest->index + 2] -= (size_t) e; | |
1746 | } | |
1747 | ||
1748 | for (i = -2; i < n_basic_blocks; ++i) | |
1749 | if (edge_checksum[i + 2]) | |
1750 | { | |
1f978f5f | 1751 | error ("basic block %i edge lists are corrupted", i); |
ca6c03ca JH |
1752 | err = 1; |
1753 | } | |
1754 | ||
1755 | last_bb_num_seen = -1; | |
1756 | num_bb_notes = 0; | |
1757 | x = rtx_first; | |
1758 | while (x) | |
1759 | { | |
1760 | if (NOTE_INSN_BASIC_BLOCK_P (x)) | |
1761 | { | |
1762 | basic_block bb = NOTE_BASIC_BLOCK (x); | |
1763 | num_bb_notes++; | |
1764 | if (bb->index != last_bb_num_seen + 1) | |
c725bd79 | 1765 | internal_error ("basic blocks not numbered consecutively"); |
ca6c03ca JH |
1766 | |
1767 | last_bb_num_seen = bb->index; | |
1768 | } | |
1769 | ||
1770 | if (!bb_info[INSN_UID (x)]) | |
1771 | { | |
1772 | switch (GET_CODE (x)) | |
1773 | { | |
1774 | case BARRIER: | |
1775 | case NOTE: | |
1776 | break; | |
1777 | ||
1778 | case CODE_LABEL: | |
1779 | /* An addr_vec is placed outside any block block. */ | |
1780 | if (NEXT_INSN (x) | |
1781 | && GET_CODE (NEXT_INSN (x)) == JUMP_INSN | |
1782 | && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC | |
1783 | || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC)) | |
1784 | { | |
1785 | x = NEXT_INSN (x); | |
1786 | } | |
1787 | ||
1788 | /* But in any case, non-deletable labels can appear anywhere. */ | |
1789 | break; | |
1790 | ||
1791 | default: | |
1f978f5f | 1792 | fatal_insn ("insn outside basic block", x); |
ca6c03ca JH |
1793 | } |
1794 | } | |
1795 | ||
1796 | if (INSN_P (x) | |
1797 | && GET_CODE (x) == JUMP_INSN | |
1798 | && returnjump_p (x) && ! condjump_p (x) | |
1799 | && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER)) | |
1f978f5f | 1800 | fatal_insn ("return not followed by barrier", x); |
ca6c03ca JH |
1801 | |
1802 | x = NEXT_INSN (x); | |
1803 | } | |
1804 | ||
1805 | if (num_bb_notes != n_basic_blocks) | |
1806 | internal_error | |
1807 | ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)", | |
1808 | num_bb_notes, n_basic_blocks); | |
1809 | ||
1810 | if (err) | |
c725bd79 | 1811 | internal_error ("verify_flow_info failed"); |
ca6c03ca JH |
1812 | |
1813 | /* Clean up. */ | |
1814 | free (bb_info); | |
1815 | free (last_visited); | |
1816 | free (edge_checksum); | |
1817 | } | |
1818 | \f | |
eaec9b3d | 1819 | /* Assume that the preceding pass has possibly eliminated jump instructions |
ca6c03ca JH |
1820 | or converted the unconditional jumps. Eliminate the edges from CFG. |
1821 | Return true if any edges are eliminated. */ | |
1822 | ||
1823 | bool | |
1824 | purge_dead_edges (bb) | |
1825 | basic_block bb; | |
1826 | { | |
1827 | edge e, next; | |
89753b3a | 1828 | rtx insn = bb->end, note; |
ca6c03ca JH |
1829 | bool purged = false; |
1830 | ||
1831 | if (GET_CODE (insn) == JUMP_INSN && !simplejump_p (insn)) | |
1832 | return false; | |
1833 | if (GET_CODE (insn) == JUMP_INSN) | |
1834 | { | |
1835 | rtx note; | |
1836 | edge b,f; | |
1837 | /* We do care only about conditional jumps and simplejumps. */ | |
1838 | if (!any_condjump_p (insn) | |
1839 | && !returnjump_p (insn) | |
1840 | && !simplejump_p (insn)) | |
1841 | return false; | |
1842 | for (e = bb->succ; e; e = next) | |
1843 | { | |
1844 | next = e->succ_next; | |
1845 | ||
7fcd7218 JH |
1846 | /* Avoid abnormal flags to leak from computed jumps turned |
1847 | into simplejumps. */ | |
1848 | ||
0e1638d4 | 1849 | e->flags &= ~EDGE_ABNORMAL; |
7fcd7218 | 1850 | |
ca6c03ca JH |
1851 | /* Check purposes we can have edge. */ |
1852 | if ((e->flags & EDGE_FALLTHRU) | |
1853 | && any_condjump_p (insn)) | |
1854 | continue; | |
1855 | if (e->dest != EXIT_BLOCK_PTR | |
1856 | && e->dest->head == JUMP_LABEL (insn)) | |
1857 | continue; | |
1858 | if (e->dest == EXIT_BLOCK_PTR | |
1859 | && returnjump_p (insn)) | |
1860 | continue; | |
1861 | purged = true; | |
1862 | remove_edge (e); | |
1863 | } | |
1864 | if (!bb->succ || !purged) | |
1865 | return false; | |
1866 | if (rtl_dump_file) | |
1867 | fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index); | |
1868 | if (!optimize) | |
1869 | return purged; | |
1870 | ||
1871 | /* Redistribute probabilities. */ | |
1872 | if (!bb->succ->succ_next) | |
1873 | { | |
1874 | bb->succ->probability = REG_BR_PROB_BASE; | |
1875 | bb->succ->count = bb->count; | |
1876 | } | |
1877 | else | |
1878 | { | |
1879 | note = find_reg_note (insn, REG_BR_PROB, NULL); | |
1880 | if (!note) | |
1881 | return purged; | |
1882 | b = BRANCH_EDGE (bb); | |
1883 | f = FALLTHRU_EDGE (bb); | |
1884 | b->probability = INTVAL (XEXP (note, 0)); | |
1885 | f->probability = REG_BR_PROB_BASE - b->probability; | |
1886 | b->count = bb->count * b->probability / REG_BR_PROB_BASE; | |
1887 | f->count = bb->count * f->probability / REG_BR_PROB_BASE; | |
1888 | } | |
1889 | return purged; | |
1890 | } | |
1891 | ||
89753b3a JJ |
1892 | /* If this instruction cannot trap, remove REG_EH_REGION notes. */ |
1893 | if (GET_CODE (insn) == INSN | |
1894 | && (note = find_reg_note (insn, REG_EH_REGION, NULL))) | |
1895 | { | |
1896 | rtx eqnote; | |
1897 | if (! may_trap_p (PATTERN (insn)) | |
1898 | || ((eqnote = find_reg_equal_equiv_note (insn)) | |
1899 | && ! may_trap_p (XEXP (eqnote, 0)))) | |
1900 | remove_note (insn, note); | |
1901 | } | |
1902 | ||
ca6c03ca JH |
1903 | /* Cleanup abnormal edges caused by throwing insns that have been |
1904 | eliminated. */ | |
1905 | if (! can_throw_internal (bb->end)) | |
1906 | for (e = bb->succ; e; e = next) | |
1907 | { | |
1908 | next = e->succ_next; | |
1909 | if (e->flags & EDGE_EH) | |
1910 | { | |
1911 | remove_edge (e); | |
1912 | purged = true; | |
1913 | } | |
1914 | } | |
1915 | ||
1916 | /* If we don't see a jump insn, we don't know exactly why the block would | |
1917 | have been broken at this point. Look for a simple, non-fallthru edge, | |
1918 | as these are only created by conditional branches. If we find such an | |
1919 | edge we know that there used to be a jump here and can then safely | |
1920 | remove all non-fallthru edges. */ | |
1921 | for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)); | |
1922 | e = e->succ_next); | |
1923 | if (!e) | |
1924 | return purged; | |
1925 | for (e = bb->succ; e; e = next) | |
1926 | { | |
1927 | next = e->succ_next; | |
1928 | if (!(e->flags & EDGE_FALLTHRU)) | |
1929 | remove_edge (e), purged = true; | |
1930 | } | |
1931 | if (!bb->succ || bb->succ->succ_next) | |
1932 | abort (); | |
1933 | bb->succ->probability = REG_BR_PROB_BASE; | |
1934 | bb->succ->count = bb->count; | |
1935 | ||
1936 | if (rtl_dump_file) | |
1937 | fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n", | |
1938 | bb->index); | |
1939 | return purged; | |
1940 | } | |
1941 | ||
eaec9b3d | 1942 | /* Search all basic blocks for potentially dead edges and purge them. |
ca6c03ca | 1943 | |
f5143c46 | 1944 | Return true iff some edge has been eliminated. |
ca6c03ca JH |
1945 | */ |
1946 | ||
1947 | bool | |
473fb060 | 1948 | purge_all_dead_edges (update_life_p) |
00baba68 | 1949 | int update_life_p; |
ca6c03ca JH |
1950 | { |
1951 | int i, purged = false; | |
710af899 | 1952 | sbitmap blocks = 0; |
473fb060 JH |
1953 | |
1954 | if (update_life_p) | |
1955 | { | |
1956 | blocks = sbitmap_alloc (n_basic_blocks); | |
1957 | sbitmap_zero (blocks); | |
1958 | } | |
ca6c03ca | 1959 | for (i = 0; i < n_basic_blocks; i++) |
473fb060 JH |
1960 | { |
1961 | bool purged_here; | |
1962 | purged_here = purge_dead_edges (BASIC_BLOCK (i)); | |
1963 | purged |= purged_here; | |
1964 | if (purged_here && update_life_p) | |
1965 | SET_BIT (blocks, i); | |
1966 | } | |
1967 | if (update_life_p && purged) | |
1968 | update_life_info (blocks, UPDATE_LIFE_GLOBAL, | |
1969 | PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE | |
1970 | | PROP_KILL_DEAD_CODE); | |
1971 | if (update_life_p) | |
1972 | sbitmap_free (blocks); | |
ca6c03ca JH |
1973 | return purged; |
1974 | } |