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c9784e6d | 1 | /* CFG cleanup for trees. |
23a5b65a | 2 | Copyright (C) 2001-2014 Free Software Foundation, Inc. |
c9784e6d KH |
3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
9dcd6f09 | 8 | the Free Software Foundation; either version 3, or (at your option) |
c9784e6d KH |
9 | any later version. |
10 | ||
11 | GCC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
c9784e6d KH |
19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
24 | #include "tree.h" | |
c9784e6d | 25 | #include "tm_p.h" |
60393bbc AM |
26 | #include "predict.h" |
27 | #include "vec.h" | |
83685514 AM |
28 | #include "hashtab.h" |
29 | #include "hash-set.h" | |
83685514 AM |
30 | #include "machmode.h" |
31 | #include "hard-reg-set.h" | |
32 | #include "input.h" | |
c9784e6d | 33 | #include "function.h" |
60393bbc AM |
34 | #include "dominance.h" |
35 | #include "cfg.h" | |
36 | #include "cfganal.h" | |
37 | #include "cfgcleanup.h" | |
38 | #include "basic-block.h" | |
39 | #include "diagnostic-core.h" | |
40 | #include "flags.h" | |
c9784e6d | 41 | #include "langhooks.h" |
2fb9a547 AM |
42 | #include "tree-ssa-alias.h" |
43 | #include "internal-fn.h" | |
44 | #include "tree-eh.h" | |
45 | #include "gimple-expr.h" | |
46 | #include "is-a.h" | |
18f429e2 | 47 | #include "gimple.h" |
45b0be94 | 48 | #include "gimplify.h" |
5be5c238 | 49 | #include "gimple-iterator.h" |
442b4905 AM |
50 | #include "gimple-ssa.h" |
51 | #include "tree-cfg.h" | |
52 | #include "tree-phinodes.h" | |
53 | #include "ssa-iterators.h" | |
d8a2d370 | 54 | #include "stringpool.h" |
442b4905 | 55 | #include "tree-ssanames.h" |
e28030cf | 56 | #include "tree-ssa-loop-manip.h" |
d8a2d370 | 57 | #include "expr.h" |
442b4905 | 58 | #include "tree-dfa.h" |
7a300452 | 59 | #include "tree-ssa.h" |
c9784e6d | 60 | #include "tree-pass.h" |
c9784e6d KH |
61 | #include "except.h" |
62 | #include "cfgloop.h" | |
c9784e6d | 63 | #include "tree-ssa-propagate.h" |
17684618 | 64 | #include "tree-scalar-evolution.h" |
c9784e6d | 65 | |
672987e8 ZD |
66 | /* The set of blocks in that at least one of the following changes happened: |
67 | -- the statement at the end of the block was changed | |
68 | -- the block was newly created | |
69 | -- the set of the predecessors of the block changed | |
70 | -- the set of the successors of the block changed | |
71 | ??? Maybe we could track these changes separately, since they determine | |
72 | what cleanups it makes sense to try on the block. */ | |
73 | bitmap cfgcleanup_altered_bbs; | |
74 | ||
c9784e6d KH |
75 | /* Remove any fallthru edge from EV. Return true if an edge was removed. */ |
76 | ||
77 | static bool | |
9771b263 | 78 | remove_fallthru_edge (vec<edge, va_gc> *ev) |
c9784e6d KH |
79 | { |
80 | edge_iterator ei; | |
81 | edge e; | |
82 | ||
83 | FOR_EACH_EDGE (e, ei, ev) | |
84 | if ((e->flags & EDGE_FALLTHRU) != 0) | |
85 | { | |
0107dca2 RB |
86 | if (e->flags & EDGE_COMPLEX) |
87 | e->flags &= ~EDGE_FALLTHRU; | |
88 | else | |
89 | remove_edge_and_dominated_blocks (e); | |
c9784e6d KH |
90 | return true; |
91 | } | |
92 | return false; | |
93 | } | |
94 | ||
726a989a | 95 | |
c9784e6d KH |
96 | /* Disconnect an unreachable block in the control expression starting |
97 | at block BB. */ | |
98 | ||
99 | static bool | |
726a989a | 100 | cleanup_control_expr_graph (basic_block bb, gimple_stmt_iterator gsi) |
c9784e6d KH |
101 | { |
102 | edge taken_edge; | |
103 | bool retval = false; | |
726a989a RB |
104 | gimple stmt = gsi_stmt (gsi); |
105 | tree val; | |
c9784e6d KH |
106 | |
107 | if (!single_succ_p (bb)) | |
108 | { | |
109 | edge e; | |
110 | edge_iterator ei; | |
6ac01510 | 111 | bool warned; |
37530014 | 112 | location_t loc; |
6ac01510 ILT |
113 | |
114 | fold_defer_overflow_warnings (); | |
37530014 RG |
115 | loc = gimple_location (stmt); |
116 | switch (gimple_code (stmt)) | |
117 | { | |
118 | case GIMPLE_COND: | |
fea4ea73 EB |
119 | val = fold_binary_loc (loc, gimple_cond_code (stmt), |
120 | boolean_type_node, | |
121 | gimple_cond_lhs (stmt), | |
122 | gimple_cond_rhs (stmt)); | |
123 | break; | |
37530014 RG |
124 | |
125 | case GIMPLE_SWITCH: | |
126 | val = gimple_switch_index (stmt); | |
127 | break; | |
128 | ||
129 | default: | |
130 | val = NULL_TREE; | |
131 | } | |
c9784e6d KH |
132 | taken_edge = find_taken_edge (bb, val); |
133 | if (!taken_edge) | |
6ac01510 ILT |
134 | { |
135 | fold_undefer_and_ignore_overflow_warnings (); | |
136 | return false; | |
137 | } | |
c9784e6d KH |
138 | |
139 | /* Remove all the edges except the one that is always executed. */ | |
6ac01510 | 140 | warned = false; |
c9784e6d KH |
141 | for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) |
142 | { | |
143 | if (e != taken_edge) | |
144 | { | |
6ac01510 ILT |
145 | if (!warned) |
146 | { | |
147 | fold_undefer_overflow_warnings | |
726a989a | 148 | (true, stmt, WARN_STRICT_OVERFLOW_CONDITIONAL); |
6ac01510 ILT |
149 | warned = true; |
150 | } | |
151 | ||
c9784e6d KH |
152 | taken_edge->probability += e->probability; |
153 | taken_edge->count += e->count; | |
672987e8 | 154 | remove_edge_and_dominated_blocks (e); |
c9784e6d KH |
155 | retval = true; |
156 | } | |
157 | else | |
158 | ei_next (&ei); | |
159 | } | |
6ac01510 ILT |
160 | if (!warned) |
161 | fold_undefer_and_ignore_overflow_warnings (); | |
c9784e6d KH |
162 | if (taken_edge->probability > REG_BR_PROB_BASE) |
163 | taken_edge->probability = REG_BR_PROB_BASE; | |
164 | } | |
165 | else | |
166 | taken_edge = single_succ_edge (bb); | |
167 | ||
672987e8 | 168 | bitmap_set_bit (cfgcleanup_altered_bbs, bb->index); |
726a989a | 169 | gsi_remove (&gsi, true); |
c9784e6d KH |
170 | taken_edge->flags = EDGE_FALLTHRU; |
171 | ||
c9784e6d KH |
172 | return retval; |
173 | } | |
174 | ||
58041fe6 MJ |
175 | /* Cleanup the GF_CALL_CTRL_ALTERING flag according to |
176 | to updated gimple_call_flags. */ | |
177 | ||
178 | static void | |
179 | cleanup_call_ctrl_altering_flag (gimple bb_end) | |
180 | { | |
181 | if (!is_gimple_call (bb_end) | |
182 | || !gimple_call_ctrl_altering_p (bb_end)) | |
183 | return; | |
184 | ||
185 | int flags = gimple_call_flags (bb_end); | |
186 | if (((flags & (ECF_CONST | ECF_PURE)) | |
187 | && !(flags & ECF_LOOPING_CONST_OR_PURE)) | |
188 | || (flags & ECF_LEAF)) | |
189 | gimple_call_set_ctrl_altering (bb_end, false); | |
190 | } | |
191 | ||
672987e8 ZD |
192 | /* Try to remove superfluous control structures in basic block BB. Returns |
193 | true if anything changes. */ | |
c9784e6d KH |
194 | |
195 | static bool | |
672987e8 | 196 | cleanup_control_flow_bb (basic_block bb) |
c9784e6d | 197 | { |
726a989a | 198 | gimple_stmt_iterator gsi; |
c9784e6d | 199 | bool retval = false; |
726a989a | 200 | gimple stmt; |
c9784e6d | 201 | |
672987e8 ZD |
202 | /* If the last statement of the block could throw and now cannot, |
203 | we need to prune cfg. */ | |
726a989a | 204 | retval |= gimple_purge_dead_eh_edges (bb); |
672987e8 | 205 | |
726a989a RB |
206 | gsi = gsi_last_bb (bb); |
207 | if (gsi_end_p (gsi)) | |
672987e8 ZD |
208 | return retval; |
209 | ||
726a989a | 210 | stmt = gsi_stmt (gsi); |
672987e8 | 211 | |
58041fe6 MJ |
212 | /* Try to cleanup ctrl altering flag for call which ends bb. */ |
213 | cleanup_call_ctrl_altering_flag (stmt); | |
214 | ||
726a989a RB |
215 | if (gimple_code (stmt) == GIMPLE_COND |
216 | || gimple_code (stmt) == GIMPLE_SWITCH) | |
217 | retval |= cleanup_control_expr_graph (bb, gsi); | |
218 | else if (gimple_code (stmt) == GIMPLE_GOTO | |
219 | && TREE_CODE (gimple_goto_dest (stmt)) == ADDR_EXPR | |
220 | && (TREE_CODE (TREE_OPERAND (gimple_goto_dest (stmt), 0)) | |
672987e8 | 221 | == LABEL_DECL)) |
c9784e6d | 222 | { |
726a989a RB |
223 | /* If we had a computed goto which has a compile-time determinable |
224 | destination, then we can eliminate the goto. */ | |
672987e8 ZD |
225 | edge e; |
226 | tree label; | |
227 | edge_iterator ei; | |
228 | basic_block target_block; | |
c9784e6d | 229 | |
672987e8 ZD |
230 | /* First look at all the outgoing edges. Delete any outgoing |
231 | edges which do not go to the right block. For the one | |
232 | edge which goes to the right block, fix up its flags. */ | |
726a989a | 233 | label = TREE_OPERAND (gimple_goto_dest (stmt), 0); |
672987e8 ZD |
234 | target_block = label_to_block (label); |
235 | for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) | |
c9784e6d | 236 | { |
672987e8 ZD |
237 | if (e->dest != target_block) |
238 | remove_edge_and_dominated_blocks (e); | |
239 | else | |
c9784e6d | 240 | { |
672987e8 ZD |
241 | /* Turn off the EDGE_ABNORMAL flag. */ |
242 | e->flags &= ~EDGE_ABNORMAL; | |
c9784e6d | 243 | |
672987e8 ZD |
244 | /* And set EDGE_FALLTHRU. */ |
245 | e->flags |= EDGE_FALLTHRU; | |
246 | ei_next (&ei); | |
247 | } | |
c9784e6d KH |
248 | } |
249 | ||
672987e8 ZD |
250 | bitmap_set_bit (cfgcleanup_altered_bbs, bb->index); |
251 | bitmap_set_bit (cfgcleanup_altered_bbs, target_block->index); | |
252 | ||
253 | /* Remove the GOTO_EXPR as it is not needed. The CFG has all the | |
254 | relevant information we need. */ | |
726a989a | 255 | gsi_remove (&gsi, true); |
672987e8 | 256 | retval = true; |
c9784e6d | 257 | } |
672987e8 ZD |
258 | |
259 | /* Check for indirect calls that have been turned into | |
260 | noreturn calls. */ | |
726a989a RB |
261 | else if (is_gimple_call (stmt) |
262 | && gimple_call_noreturn_p (stmt) | |
263 | && remove_fallthru_edge (bb->succs)) | |
672987e8 ZD |
264 | retval = true; |
265 | ||
c9784e6d KH |
266 | return retval; |
267 | } | |
268 | ||
269 | /* Return true if basic block BB does nothing except pass control | |
270 | flow to another block and that we can safely insert a label at | |
271 | the start of the successor block. | |
272 | ||
273 | As a precondition, we require that BB be not equal to | |
6626665f | 274 | the entry block. */ |
c9784e6d KH |
275 | |
276 | static bool | |
277 | tree_forwarder_block_p (basic_block bb, bool phi_wanted) | |
278 | { | |
726a989a | 279 | gimple_stmt_iterator gsi; |
f99fcb3b | 280 | location_t locus; |
c9784e6d KH |
281 | |
282 | /* BB must have a single outgoing edge. */ | |
283 | if (single_succ_p (bb) != 1 | |
284 | /* If PHI_WANTED is false, BB must not have any PHI nodes. | |
285 | Otherwise, BB must have PHI nodes. */ | |
726a989a | 286 | || gimple_seq_empty_p (phi_nodes (bb)) == phi_wanted |
6626665f | 287 | /* BB may not be a predecessor of the exit block. */ |
fefa31b5 | 288 | || single_succ (bb) == EXIT_BLOCK_PTR_FOR_FN (cfun) |
c9784e6d KH |
289 | /* Nor should this be an infinite loop. */ |
290 | || single_succ (bb) == bb | |
291 | /* BB may not have an abnormal outgoing edge. */ | |
292 | || (single_succ_edge (bb)->flags & EDGE_ABNORMAL)) | |
293 | return false; | |
294 | ||
fefa31b5 | 295 | gcc_checking_assert (bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)); |
c9784e6d | 296 | |
f99fcb3b JJ |
297 | locus = single_succ_edge (bb)->goto_locus; |
298 | ||
1d65f45c RH |
299 | /* There should not be an edge coming from entry, or an EH edge. */ |
300 | { | |
301 | edge_iterator ei; | |
302 | edge e; | |
303 | ||
304 | FOR_EACH_EDGE (e, ei, bb->preds) | |
fefa31b5 | 305 | if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun) || (e->flags & EDGE_EH)) |
1d65f45c | 306 | return false; |
f99fcb3b JJ |
307 | /* If goto_locus of any of the edges differs, prevent removing |
308 | the forwarder block for -O0. */ | |
309 | else if (optimize == 0 && e->goto_locus != locus) | |
310 | return false; | |
1d65f45c RH |
311 | } |
312 | ||
c9784e6d KH |
313 | /* Now walk through the statements backward. We can ignore labels, |
314 | anything else means this is not a forwarder block. */ | |
726a989a | 315 | for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi)) |
c9784e6d | 316 | { |
726a989a | 317 | gimple stmt = gsi_stmt (gsi); |
c9784e6d | 318 | |
726a989a | 319 | switch (gimple_code (stmt)) |
c9784e6d | 320 | { |
726a989a RB |
321 | case GIMPLE_LABEL: |
322 | if (DECL_NONLOCAL (gimple_label_label (stmt))) | |
c9784e6d | 323 | return false; |
f99fcb3b JJ |
324 | if (optimize == 0 && gimple_location (stmt) != locus) |
325 | return false; | |
c9784e6d KH |
326 | break; |
327 | ||
b5b8b0ac AO |
328 | /* ??? For now, hope there's a corresponding debug |
329 | assignment at the destination. */ | |
330 | case GIMPLE_DEBUG: | |
331 | break; | |
332 | ||
c9784e6d KH |
333 | default: |
334 | return false; | |
335 | } | |
336 | } | |
337 | ||
c9784e6d KH |
338 | if (current_loops) |
339 | { | |
340 | basic_block dest; | |
a3afdbb8 | 341 | /* Protect loop headers. */ |
c9784e6d KH |
342 | if (bb->loop_father->header == bb) |
343 | return false; | |
c9784e6d | 344 | |
a3afdbb8 BC |
345 | dest = EDGE_SUCC (bb, 0)->dest; |
346 | /* Protect loop preheaders and latches if requested. */ | |
c9784e6d | 347 | if (dest->loop_father->header == dest) |
a3afdbb8 | 348 | { |
fba7c564 RB |
349 | if (bb->loop_father == dest->loop_father) |
350 | { | |
351 | if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) | |
352 | return false; | |
353 | /* If bb doesn't have a single predecessor we'd make this | |
354 | loop have multiple latches. Don't do that if that | |
355 | would in turn require disambiguating them. */ | |
356 | return (single_pred_p (bb) | |
357 | || loops_state_satisfies_p | |
358 | (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)); | |
359 | } | |
360 | else if (bb->loop_father == loop_outer (dest->loop_father)) | |
361 | return !loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS); | |
362 | /* Always preserve other edges into loop headers that are | |
363 | not simple latches or preheaders. */ | |
364 | return false; | |
a3afdbb8 | 365 | } |
c9784e6d | 366 | } |
a3afdbb8 | 367 | |
c9784e6d KH |
368 | return true; |
369 | } | |
370 | ||
c9784e6d KH |
371 | /* If all the PHI nodes in DEST have alternatives for E1 and E2 and |
372 | those alternatives are equal in each of the PHI nodes, then return | |
373 | true, else return false. */ | |
374 | ||
375 | static bool | |
376 | phi_alternatives_equal (basic_block dest, edge e1, edge e2) | |
377 | { | |
378 | int n1 = e1->dest_idx; | |
379 | int n2 = e2->dest_idx; | |
726a989a | 380 | gimple_stmt_iterator gsi; |
c9784e6d | 381 | |
726a989a | 382 | for (gsi = gsi_start_phis (dest); !gsi_end_p (gsi); gsi_next (&gsi)) |
c9784e6d | 383 | { |
726a989a RB |
384 | gimple phi = gsi_stmt (gsi); |
385 | tree val1 = gimple_phi_arg_def (phi, n1); | |
386 | tree val2 = gimple_phi_arg_def (phi, n2); | |
c9784e6d KH |
387 | |
388 | gcc_assert (val1 != NULL_TREE); | |
389 | gcc_assert (val2 != NULL_TREE); | |
390 | ||
391 | if (!operand_equal_for_phi_arg_p (val1, val2)) | |
392 | return false; | |
393 | } | |
394 | ||
395 | return true; | |
396 | } | |
397 | ||
672987e8 | 398 | /* Removes forwarder block BB. Returns false if this failed. */ |
c9784e6d KH |
399 | |
400 | static bool | |
672987e8 | 401 | remove_forwarder_block (basic_block bb) |
c9784e6d KH |
402 | { |
403 | edge succ = single_succ_edge (bb), e, s; | |
404 | basic_block dest = succ->dest; | |
726a989a | 405 | gimple label; |
c9784e6d | 406 | edge_iterator ei; |
726a989a | 407 | gimple_stmt_iterator gsi, gsi_to; |
70235ab9 | 408 | bool can_move_debug_stmts; |
c9784e6d KH |
409 | |
410 | /* We check for infinite loops already in tree_forwarder_block_p. | |
411 | However it may happen that the infinite loop is created | |
412 | afterwards due to removal of forwarders. */ | |
413 | if (dest == bb) | |
414 | return false; | |
415 | ||
28e5ca15 RB |
416 | /* If the destination block consists of a nonlocal label or is a |
417 | EH landing pad, do not merge it. */ | |
c9784e6d KH |
418 | label = first_stmt (dest); |
419 | if (label | |
726a989a | 420 | && gimple_code (label) == GIMPLE_LABEL |
28e5ca15 RB |
421 | && (DECL_NONLOCAL (gimple_label_label (label)) |
422 | || EH_LANDING_PAD_NR (gimple_label_label (label)) != 0)) | |
c9784e6d KH |
423 | return false; |
424 | ||
425 | /* If there is an abnormal edge to basic block BB, but not into | |
426 | dest, problems might occur during removal of the phi node at out | |
427 | of ssa due to overlapping live ranges of registers. | |
428 | ||
429 | If there is an abnormal edge in DEST, the problems would occur | |
430 | anyway since cleanup_dead_labels would then merge the labels for | |
431 | two different eh regions, and rest of exception handling code | |
432 | does not like it. | |
433 | ||
434 | So if there is an abnormal edge to BB, proceed only if there is | |
435 | no abnormal edge to DEST and there are no phi nodes in DEST. */ | |
31ff2426 NF |
436 | if (bb_has_abnormal_pred (bb) |
437 | && (bb_has_abnormal_pred (dest) | |
1197e789 RG |
438 | || !gimple_seq_empty_p (phi_nodes (dest)))) |
439 | return false; | |
c9784e6d KH |
440 | |
441 | /* If there are phi nodes in DEST, and some of the blocks that are | |
442 | predecessors of BB are also predecessors of DEST, check that the | |
443 | phi node arguments match. */ | |
726a989a | 444 | if (!gimple_seq_empty_p (phi_nodes (dest))) |
c9784e6d KH |
445 | { |
446 | FOR_EACH_EDGE (e, ei, bb->preds) | |
447 | { | |
448 | s = find_edge (e->src, dest); | |
449 | if (!s) | |
450 | continue; | |
451 | ||
452 | if (!phi_alternatives_equal (dest, succ, s)) | |
453 | return false; | |
454 | } | |
455 | } | |
456 | ||
dc764d10 | 457 | can_move_debug_stmts = MAY_HAVE_DEBUG_STMTS && single_pred_p (dest); |
70235ab9 | 458 | |
fba7c564 RB |
459 | basic_block pred = NULL; |
460 | if (single_pred_p (bb)) | |
461 | pred = single_pred (bb); | |
462 | ||
c9784e6d KH |
463 | /* Redirect the edges. */ |
464 | for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) | |
465 | { | |
672987e8 ZD |
466 | bitmap_set_bit (cfgcleanup_altered_bbs, e->src->index); |
467 | ||
c9784e6d KH |
468 | if (e->flags & EDGE_ABNORMAL) |
469 | { | |
470 | /* If there is an abnormal edge, redirect it anyway, and | |
471 | move the labels to the new block to make it legal. */ | |
472 | s = redirect_edge_succ_nodup (e, dest); | |
473 | } | |
474 | else | |
475 | s = redirect_edge_and_branch (e, dest); | |
476 | ||
477 | if (s == e) | |
478 | { | |
479 | /* Create arguments for the phi nodes, since the edge was not | |
480 | here before. */ | |
726a989a RB |
481 | for (gsi = gsi_start_phis (dest); |
482 | !gsi_end_p (gsi); | |
483 | gsi_next (&gsi)) | |
484 | { | |
485 | gimple phi = gsi_stmt (gsi); | |
f5045c96 | 486 | source_location l = gimple_phi_arg_location_from_edge (phi, succ); |
2724573f RB |
487 | tree def = gimple_phi_arg_def (phi, succ->dest_idx); |
488 | add_phi_arg (phi, unshare_expr (def), s, l); | |
726a989a | 489 | } |
c9784e6d | 490 | } |
c9784e6d KH |
491 | } |
492 | ||
1197e789 RG |
493 | /* Move nonlocal labels and computed goto targets as well as user |
494 | defined labels and labels with an EH landing pad number to the | |
495 | new block, so that the redirection of the abnormal edges works, | |
496 | jump targets end up in a sane place and debug information for | |
497 | labels is retained. */ | |
498 | gsi_to = gsi_start_bb (dest); | |
499 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); ) | |
500 | { | |
501 | tree decl; | |
502 | label = gsi_stmt (gsi); | |
503 | if (is_gimple_debug (label)) | |
504 | break; | |
505 | decl = gimple_label_label (label); | |
506 | if (EH_LANDING_PAD_NR (decl) != 0 | |
507 | || DECL_NONLOCAL (decl) | |
508 | || FORCED_LABEL (decl) | |
509 | || !DECL_ARTIFICIAL (decl)) | |
510 | { | |
511 | gsi_remove (&gsi, false); | |
512 | gsi_insert_before (&gsi_to, label, GSI_SAME_STMT); | |
513 | } | |
514 | else | |
515 | gsi_next (&gsi); | |
516 | } | |
517 | ||
dc764d10 | 518 | /* Move debug statements if the destination has a single predecessor. */ |
70235ab9 | 519 | if (can_move_debug_stmts) |
c9784e6d | 520 | { |
1197e789 RG |
521 | gsi_to = gsi_after_labels (dest); |
522 | for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); ) | |
c9784e6d | 523 | { |
70235ab9 JJ |
524 | gimple debug = gsi_stmt (gsi); |
525 | if (!is_gimple_debug (debug)) | |
1197e789 | 526 | break; |
726a989a | 527 | gsi_remove (&gsi, false); |
70235ab9 | 528 | gsi_insert_before (&gsi_to, debug, GSI_SAME_STMT); |
c9784e6d KH |
529 | } |
530 | } | |
531 | ||
672987e8 ZD |
532 | bitmap_set_bit (cfgcleanup_altered_bbs, dest->index); |
533 | ||
c9784e6d KH |
534 | /* Update the dominators. */ |
535 | if (dom_info_available_p (CDI_DOMINATORS)) | |
536 | { | |
537 | basic_block dom, dombb, domdest; | |
538 | ||
539 | dombb = get_immediate_dominator (CDI_DOMINATORS, bb); | |
540 | domdest = get_immediate_dominator (CDI_DOMINATORS, dest); | |
541 | if (domdest == bb) | |
542 | { | |
543 | /* Shortcut to avoid calling (relatively expensive) | |
544 | nearest_common_dominator unless necessary. */ | |
545 | dom = dombb; | |
546 | } | |
547 | else | |
548 | dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb); | |
549 | ||
550 | set_immediate_dominator (CDI_DOMINATORS, dest, dom); | |
551 | } | |
552 | ||
a3afdbb8 BC |
553 | /* Adjust latch infomation of BB's parent loop as otherwise |
554 | the cfg hook has a hard time not to kill the loop. */ | |
555 | if (current_loops && bb->loop_father->latch == bb) | |
fba7c564 | 556 | bb->loop_father->latch = pred; |
a3afdbb8 | 557 | |
c9784e6d KH |
558 | /* And kill the forwarder block. */ |
559 | delete_basic_block (bb); | |
560 | ||
561 | return true; | |
562 | } | |
563 | ||
566d09ef JH |
564 | /* STMT is a call that has been discovered noreturn. Fixup the CFG |
565 | and remove LHS. Return true if something changed. */ | |
566 | ||
567 | bool | |
568 | fixup_noreturn_call (gimple stmt) | |
569 | { | |
570 | basic_block bb = gimple_bb (stmt); | |
566d09ef JH |
571 | |
572 | if (gimple_call_builtin_p (stmt, BUILT_IN_RETURN)) | |
573 | return false; | |
574 | ||
575 | /* First split basic block if stmt is not last. */ | |
576 | if (stmt != gsi_stmt (gsi_last_bb (bb))) | |
c83ee180 JJ |
577 | { |
578 | if (stmt == gsi_stmt (gsi_last_nondebug_bb (bb))) | |
579 | { | |
580 | /* Don't split if there are only debug stmts | |
581 | after stmt, that can result in -fcompare-debug | |
582 | failures. Remove the debug stmts instead, | |
583 | they should be all unreachable anyway. */ | |
584 | gimple_stmt_iterator gsi = gsi_for_stmt (stmt); | |
585 | for (gsi_next (&gsi); !gsi_end_p (gsi); ) | |
586 | gsi_remove (&gsi, true); | |
587 | } | |
588 | else | |
589 | split_block (bb, stmt); | |
590 | } | |
566d09ef | 591 | |
2f1b0141 EB |
592 | /* If there is an LHS, remove it. */ |
593 | tree lhs = gimple_call_lhs (stmt); | |
594 | if (lhs) | |
566d09ef | 595 | { |
566d09ef | 596 | gimple_call_set_lhs (stmt, NULL_TREE); |
02d635a2 | 597 | |
2f1b0141 EB |
598 | /* We need to fix up the SSA name to avoid checking errors. */ |
599 | if (TREE_CODE (lhs) == SSA_NAME) | |
566d09ef | 600 | { |
2f1b0141 EB |
601 | tree new_var = create_tmp_reg (TREE_TYPE (lhs), NULL); |
602 | SET_SSA_NAME_VAR_OR_IDENTIFIER (lhs, new_var); | |
603 | SSA_NAME_DEF_STMT (lhs) = gimple_build_nop (); | |
604 | set_ssa_default_def (cfun, new_var, lhs); | |
566d09ef | 605 | } |
2f1b0141 | 606 | |
566d09ef | 607 | update_stmt (stmt); |
566d09ef | 608 | } |
2f1b0141 EB |
609 | |
610 | return remove_fallthru_edge (bb->succs); | |
566d09ef JH |
611 | } |
612 | ||
613 | ||
672987e8 ZD |
614 | /* Split basic blocks on calls in the middle of a basic block that are now |
615 | known not to return, and remove the unreachable code. */ | |
c9784e6d KH |
616 | |
617 | static bool | |
58041fe6 | 618 | split_bb_on_noreturn_calls (basic_block bb) |
c9784e6d | 619 | { |
c9784e6d | 620 | bool changed = false; |
58041fe6 | 621 | gimple_stmt_iterator gsi; |
c9784e6d | 622 | |
58041fe6 MJ |
623 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
624 | { | |
625 | gimple stmt = gsi_stmt (gsi); | |
672987e8 | 626 | |
58041fe6 MJ |
627 | if (!is_gimple_call (stmt)) |
628 | continue; | |
629 | ||
630 | if (gimple_call_noreturn_p (stmt)) | |
566d09ef | 631 | changed |= fixup_noreturn_call (stmt); |
58041fe6 | 632 | } |
c9784e6d | 633 | |
58041fe6 MJ |
634 | if (changed) |
635 | bitmap_set_bit (cfgcleanup_altered_bbs, bb->index); | |
c9784e6d KH |
636 | return changed; |
637 | } | |
638 | ||
672987e8 ZD |
639 | /* Tries to cleanup cfg in basic block BB. Returns true if anything |
640 | changes. */ | |
c9784e6d | 641 | |
89e80dd4 | 642 | static bool |
672987e8 | 643 | cleanup_tree_cfg_bb (basic_block bb) |
c9784e6d | 644 | { |
65e7bfe3 | 645 | bool retval = cleanup_control_flow_bb (bb); |
b8698a0f | 646 | |
f99fcb3b | 647 | if (tree_forwarder_block_p (bb, false) |
672987e8 ZD |
648 | && remove_forwarder_block (bb)) |
649 | return true; | |
c9784e6d | 650 | |
89e80dd4 DN |
651 | /* Merging the blocks may create new opportunities for folding |
652 | conditional branches (due to the elimination of single-valued PHI | |
653 | nodes). */ | |
672987e8 ZD |
654 | if (single_succ_p (bb) |
655 | && can_merge_blocks_p (bb, single_succ (bb))) | |
656 | { | |
657 | merge_blocks (bb, single_succ (bb)); | |
658 | return true; | |
659 | } | |
660 | ||
661 | return retval; | |
662 | } | |
663 | ||
664 | /* Iterate the cfg cleanups, while anything changes. */ | |
665 | ||
666 | static bool | |
667 | cleanup_tree_cfg_1 (void) | |
668 | { | |
669 | bool retval = false; | |
670 | basic_block bb; | |
671 | unsigned i, n; | |
672 | ||
672987e8 ZD |
673 | /* Prepare the worklists of altered blocks. */ |
674 | cfgcleanup_altered_bbs = BITMAP_ALLOC (NULL); | |
675 | ||
676 | /* During forwarder block cleanup, we may redirect edges out of | |
677 | SWITCH_EXPRs, which can get expensive. So we want to enable | |
678 | recording of edge to CASE_LABEL_EXPR. */ | |
679 | start_recording_case_labels (); | |
89e80dd4 | 680 | |
11cd3bed | 681 | /* Start by iterating over all basic blocks. We cannot use FOR_EACH_BB_FN, |
672987e8 | 682 | since the basic blocks may get removed. */ |
8b1c6fd7 | 683 | n = last_basic_block_for_fn (cfun); |
672987e8 ZD |
684 | for (i = NUM_FIXED_BLOCKS; i < n; i++) |
685 | { | |
06e28de2 | 686 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
672987e8 | 687 | if (bb) |
58041fe6 MJ |
688 | { |
689 | retval |= cleanup_tree_cfg_bb (bb); | |
690 | retval |= split_bb_on_noreturn_calls (bb); | |
691 | } | |
672987e8 ZD |
692 | } |
693 | ||
694 | /* Now process the altered blocks, as long as any are available. */ | |
695 | while (!bitmap_empty_p (cfgcleanup_altered_bbs)) | |
696 | { | |
697 | i = bitmap_first_set_bit (cfgcleanup_altered_bbs); | |
698 | bitmap_clear_bit (cfgcleanup_altered_bbs, i); | |
699 | if (i < NUM_FIXED_BLOCKS) | |
700 | continue; | |
701 | ||
06e28de2 | 702 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
672987e8 ZD |
703 | if (!bb) |
704 | continue; | |
705 | ||
706 | retval |= cleanup_tree_cfg_bb (bb); | |
707 | ||
58041fe6 | 708 | /* Rerun split_bb_on_noreturn_calls, in case we have altered any noreturn |
672987e8 | 709 | calls. */ |
58041fe6 | 710 | retval |= split_bb_on_noreturn_calls (bb); |
672987e8 | 711 | } |
b8698a0f | 712 | |
672987e8 ZD |
713 | end_recording_case_labels (); |
714 | BITMAP_FREE (cfgcleanup_altered_bbs); | |
89e80dd4 DN |
715 | return retval; |
716 | } | |
717 | ||
718 | ||
e3594cb3 DN |
719 | /* Remove unreachable blocks and other miscellaneous clean up work. |
720 | Return true if the flowgraph was modified, false otherwise. */ | |
89e80dd4 | 721 | |
592c303d ZD |
722 | static bool |
723 | cleanup_tree_cfg_noloop (void) | |
89e80dd4 | 724 | { |
672987e8 | 725 | bool changed; |
89e80dd4 DN |
726 | |
727 | timevar_push (TV_TREE_CLEANUP_CFG); | |
728 | ||
e3594cb3 | 729 | /* Iterate until there are no more cleanups left to do. If any |
672987e8 ZD |
730 | iteration changed the flowgraph, set CHANGED to true. |
731 | ||
732 | If dominance information is available, there cannot be any unreachable | |
733 | blocks. */ | |
2b28c07a | 734 | if (!dom_info_available_p (CDI_DOMINATORS)) |
e3594cb3 | 735 | { |
672987e8 ZD |
736 | changed = delete_unreachable_blocks (); |
737 | calculate_dominance_info (CDI_DOMINATORS); | |
e3594cb3 | 738 | } |
672987e8 | 739 | else |
30251f7a ZD |
740 | { |
741 | #ifdef ENABLE_CHECKING | |
742 | verify_dominators (CDI_DOMINATORS); | |
743 | #endif | |
744 | changed = false; | |
745 | } | |
c9784e6d | 746 | |
672987e8 ZD |
747 | changed |= cleanup_tree_cfg_1 (); |
748 | ||
2b28c07a | 749 | gcc_assert (dom_info_available_p (CDI_DOMINATORS)); |
c9784e6d KH |
750 | compact_blocks (); |
751 | ||
752 | #ifdef ENABLE_CHECKING | |
753 | verify_flow_info (); | |
754 | #endif | |
89e80dd4 | 755 | |
c9784e6d | 756 | timevar_pop (TV_TREE_CLEANUP_CFG); |
89e80dd4 | 757 | |
592c303d | 758 | if (changed && current_loops) |
f87000d0 | 759 | loops_state_set (LOOPS_NEED_FIXUP); |
592c303d | 760 | |
e3594cb3 | 761 | return changed; |
c9784e6d KH |
762 | } |
763 | ||
592c303d | 764 | /* Repairs loop structures. */ |
c9784e6d | 765 | |
592c303d ZD |
766 | static void |
767 | repair_loop_structures (void) | |
c9784e6d | 768 | { |
a222c01a | 769 | bitmap changed_bbs; |
8e89b5b5 | 770 | unsigned n_new_loops; |
a222c01a | 771 | |
cc360b36 SB |
772 | calculate_dominance_info (CDI_DOMINATORS); |
773 | ||
a222c01a MM |
774 | timevar_push (TV_REPAIR_LOOPS); |
775 | changed_bbs = BITMAP_ALLOC (NULL); | |
8e89b5b5 | 776 | n_new_loops = fix_loop_structure (changed_bbs); |
c9784e6d | 777 | |
592c303d ZD |
778 | /* This usually does nothing. But sometimes parts of cfg that originally |
779 | were inside a loop get out of it due to edge removal (since they | |
8e89b5b5 RB |
780 | become unreachable by back edges from latch). Also a former |
781 | irreducible loop can become reducible - in this case force a full | |
782 | rewrite into loop-closed SSA form. */ | |
f87000d0 | 783 | if (loops_state_satisfies_p (LOOP_CLOSED_SSA)) |
8e89b5b5 RB |
784 | rewrite_into_loop_closed_ssa (n_new_loops ? NULL : changed_bbs, |
785 | TODO_update_ssa); | |
c9784e6d | 786 | |
592c303d | 787 | BITMAP_FREE (changed_bbs); |
c9784e6d KH |
788 | |
789 | #ifdef ENABLE_CHECKING | |
592c303d | 790 | verify_loop_structure (); |
c9784e6d | 791 | #endif |
592c303d ZD |
792 | scev_reset (); |
793 | ||
a222c01a | 794 | timevar_pop (TV_REPAIR_LOOPS); |
592c303d ZD |
795 | } |
796 | ||
797 | /* Cleanup cfg and repair loop structures. */ | |
798 | ||
799 | bool | |
800 | cleanup_tree_cfg (void) | |
801 | { | |
802 | bool changed = cleanup_tree_cfg_noloop (); | |
803 | ||
804 | if (current_loops != NULL | |
f87000d0 | 805 | && loops_state_satisfies_p (LOOPS_NEED_FIXUP)) |
592c303d ZD |
806 | repair_loop_structures (); |
807 | ||
1994bfea | 808 | return changed; |
c9784e6d KH |
809 | } |
810 | ||
a9e0d843 RB |
811 | /* Tries to merge the PHI nodes at BB into those at BB's sole successor. |
812 | Returns true if successful. */ | |
c9784e6d | 813 | |
a9e0d843 | 814 | static bool |
c9784e6d KH |
815 | remove_forwarder_block_with_phi (basic_block bb) |
816 | { | |
817 | edge succ = single_succ_edge (bb); | |
818 | basic_block dest = succ->dest; | |
726a989a | 819 | gimple label; |
c9784e6d KH |
820 | basic_block dombb, domdest, dom; |
821 | ||
822 | /* We check for infinite loops already in tree_forwarder_block_p. | |
823 | However it may happen that the infinite loop is created | |
824 | afterwards due to removal of forwarders. */ | |
825 | if (dest == bb) | |
a9e0d843 | 826 | return false; |
c9784e6d KH |
827 | |
828 | /* If the destination block consists of a nonlocal label, do not | |
829 | merge it. */ | |
830 | label = first_stmt (dest); | |
831 | if (label | |
726a989a RB |
832 | && gimple_code (label) == GIMPLE_LABEL |
833 | && DECL_NONLOCAL (gimple_label_label (label))) | |
a9e0d843 | 834 | return false; |
c9784e6d | 835 | |
d731ee04 BC |
836 | /* Record BB's single pred in case we need to update the father |
837 | loop's latch information later. */ | |
838 | basic_block pred = NULL; | |
839 | if (single_pred_p (bb)) | |
840 | pred = single_pred (bb); | |
841 | ||
c9784e6d KH |
842 | /* Redirect each incoming edge to BB to DEST. */ |
843 | while (EDGE_COUNT (bb->preds) > 0) | |
844 | { | |
845 | edge e = EDGE_PRED (bb, 0), s; | |
726a989a | 846 | gimple_stmt_iterator gsi; |
c9784e6d KH |
847 | |
848 | s = find_edge (e->src, dest); | |
849 | if (s) | |
850 | { | |
851 | /* We already have an edge S from E->src to DEST. If S and | |
852 | E->dest's sole successor edge have the same PHI arguments | |
853 | at DEST, redirect S to DEST. */ | |
854 | if (phi_alternatives_equal (dest, s, succ)) | |
855 | { | |
856 | e = redirect_edge_and_branch (e, dest); | |
ea7e6d5a | 857 | redirect_edge_var_map_clear (e); |
c9784e6d KH |
858 | continue; |
859 | } | |
860 | ||
861 | /* PHI arguments are different. Create a forwarder block by | |
862 | splitting E so that we can merge PHI arguments on E to | |
863 | DEST. */ | |
864 | e = single_succ_edge (split_edge (e)); | |
865 | } | |
866 | ||
867 | s = redirect_edge_and_branch (e, dest); | |
868 | ||
869 | /* redirect_edge_and_branch must not create a new edge. */ | |
870 | gcc_assert (s == e); | |
871 | ||
872 | /* Add to the PHI nodes at DEST each PHI argument removed at the | |
873 | destination of E. */ | |
726a989a RB |
874 | for (gsi = gsi_start_phis (dest); |
875 | !gsi_end_p (gsi); | |
876 | gsi_next (&gsi)) | |
c9784e6d | 877 | { |
726a989a RB |
878 | gimple phi = gsi_stmt (gsi); |
879 | tree def = gimple_phi_arg_def (phi, succ->dest_idx); | |
f5045c96 | 880 | source_location locus = gimple_phi_arg_location_from_edge (phi, succ); |
c9784e6d KH |
881 | |
882 | if (TREE_CODE (def) == SSA_NAME) | |
883 | { | |
c9784e6d KH |
884 | /* If DEF is one of the results of PHI nodes removed during |
885 | redirection, replace it with the PHI argument that used | |
886 | to be on E. */ | |
b787e7a2 TS |
887 | vec<edge_var_map> *head = redirect_edge_var_map_vector (e); |
888 | size_t length = head ? head->length () : 0; | |
889 | for (size_t i = 0; i < length; i++) | |
c9784e6d | 890 | { |
b787e7a2 | 891 | edge_var_map *vm = &(*head)[i]; |
ea7e6d5a AH |
892 | tree old_arg = redirect_edge_var_map_result (vm); |
893 | tree new_arg = redirect_edge_var_map_def (vm); | |
c9784e6d KH |
894 | |
895 | if (def == old_arg) | |
896 | { | |
897 | def = new_arg; | |
f5045c96 | 898 | locus = redirect_edge_var_map_location (vm); |
c9784e6d KH |
899 | break; |
900 | } | |
901 | } | |
902 | } | |
903 | ||
9e227d60 | 904 | add_phi_arg (phi, def, s, locus); |
c9784e6d KH |
905 | } |
906 | ||
ea7e6d5a | 907 | redirect_edge_var_map_clear (e); |
c9784e6d KH |
908 | } |
909 | ||
910 | /* Update the dominators. */ | |
911 | dombb = get_immediate_dominator (CDI_DOMINATORS, bb); | |
912 | domdest = get_immediate_dominator (CDI_DOMINATORS, dest); | |
913 | if (domdest == bb) | |
914 | { | |
915 | /* Shortcut to avoid calling (relatively expensive) | |
916 | nearest_common_dominator unless necessary. */ | |
917 | dom = dombb; | |
918 | } | |
919 | else | |
920 | dom = nearest_common_dominator (CDI_DOMINATORS, domdest, dombb); | |
921 | ||
922 | set_immediate_dominator (CDI_DOMINATORS, dest, dom); | |
923 | ||
d731ee04 BC |
924 | /* Adjust latch infomation of BB's parent loop as otherwise |
925 | the cfg hook has a hard time not to kill the loop. */ | |
926 | if (current_loops && bb->loop_father->latch == bb) | |
927 | bb->loop_father->latch = pred; | |
928 | ||
c9784e6d KH |
929 | /* Remove BB since all of BB's incoming edges have been redirected |
930 | to DEST. */ | |
931 | delete_basic_block (bb); | |
a9e0d843 RB |
932 | |
933 | return true; | |
c9784e6d KH |
934 | } |
935 | ||
936 | /* This pass merges PHI nodes if one feeds into another. For example, | |
937 | suppose we have the following: | |
938 | ||
939 | goto <bb 9> (<L9>); | |
940 | ||
941 | <L8>:; | |
942 | tem_17 = foo (); | |
943 | ||
944 | # tem_6 = PHI <tem_17(8), tem_23(7)>; | |
945 | <L9>:; | |
946 | ||
947 | # tem_3 = PHI <tem_6(9), tem_2(5)>; | |
948 | <L10>:; | |
949 | ||
950 | Then we merge the first PHI node into the second one like so: | |
951 | ||
952 | goto <bb 9> (<L10>); | |
953 | ||
954 | <L8>:; | |
955 | tem_17 = foo (); | |
956 | ||
957 | # tem_3 = PHI <tem_23(7), tem_2(5), tem_17(8)>; | |
958 | <L10>:; | |
959 | */ | |
960 | ||
be55bfe6 TS |
961 | namespace { |
962 | ||
963 | const pass_data pass_data_merge_phi = | |
964 | { | |
965 | GIMPLE_PASS, /* type */ | |
966 | "mergephi", /* name */ | |
967 | OPTGROUP_NONE, /* optinfo_flags */ | |
be55bfe6 TS |
968 | TV_TREE_MERGE_PHI, /* tv_id */ |
969 | ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
970 | 0, /* properties_provided */ | |
971 | 0, /* properties_destroyed */ | |
972 | 0, /* todo_flags_start */ | |
3bea341f | 973 | 0, /* todo_flags_finish */ |
be55bfe6 TS |
974 | }; |
975 | ||
976 | class pass_merge_phi : public gimple_opt_pass | |
c9784e6d | 977 | { |
be55bfe6 TS |
978 | public: |
979 | pass_merge_phi (gcc::context *ctxt) | |
980 | : gimple_opt_pass (pass_data_merge_phi, ctxt) | |
981 | {} | |
982 | ||
983 | /* opt_pass methods: */ | |
984 | opt_pass * clone () { return new pass_merge_phi (m_ctxt); } | |
985 | virtual unsigned int execute (function *); | |
986 | ||
987 | }; // class pass_merge_phi | |
988 | ||
989 | unsigned int | |
990 | pass_merge_phi::execute (function *fun) | |
991 | { | |
992 | basic_block *worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (fun)); | |
c9784e6d KH |
993 | basic_block *current = worklist; |
994 | basic_block bb; | |
995 | ||
996 | calculate_dominance_info (CDI_DOMINATORS); | |
997 | ||
998 | /* Find all PHI nodes that we may be able to merge. */ | |
be55bfe6 | 999 | FOR_EACH_BB_FN (bb, fun) |
c9784e6d KH |
1000 | { |
1001 | basic_block dest; | |
1002 | ||
1003 | /* Look for a forwarder block with PHI nodes. */ | |
1004 | if (!tree_forwarder_block_p (bb, true)) | |
1005 | continue; | |
1006 | ||
1007 | dest = single_succ (bb); | |
1008 | ||
1009 | /* We have to feed into another basic block with PHI | |
1010 | nodes. */ | |
8eacd016 | 1011 | if (gimple_seq_empty_p (phi_nodes (dest)) |
c9784e6d KH |
1012 | /* We don't want to deal with a basic block with |
1013 | abnormal edges. */ | |
31ff2426 | 1014 | || bb_has_abnormal_pred (bb)) |
c9784e6d KH |
1015 | continue; |
1016 | ||
1017 | if (!dominated_by_p (CDI_DOMINATORS, dest, bb)) | |
1018 | { | |
1019 | /* If BB does not dominate DEST, then the PHI nodes at | |
1020 | DEST must be the only users of the results of the PHI | |
1021 | nodes at BB. */ | |
1022 | *current++ = bb; | |
1023 | } | |
ea65cd37 JL |
1024 | else |
1025 | { | |
726a989a | 1026 | gimple_stmt_iterator gsi; |
338b5886 | 1027 | unsigned int dest_idx = single_succ_edge (bb)->dest_idx; |
ea65cd37 JL |
1028 | |
1029 | /* BB dominates DEST. There may be many users of the PHI | |
1030 | nodes in BB. However, there is still a trivial case we | |
1031 | can handle. If the result of every PHI in BB is used | |
1032 | only by a PHI in DEST, then we can trivially merge the | |
1033 | PHI nodes from BB into DEST. */ | |
726a989a RB |
1034 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); |
1035 | gsi_next (&gsi)) | |
ea65cd37 | 1036 | { |
726a989a RB |
1037 | gimple phi = gsi_stmt (gsi); |
1038 | tree result = gimple_phi_result (phi); | |
ea65cd37 | 1039 | use_operand_p imm_use; |
726a989a | 1040 | gimple use_stmt; |
ea65cd37 JL |
1041 | |
1042 | /* If the PHI's result is never used, then we can just | |
1043 | ignore it. */ | |
bfc646bf | 1044 | if (has_zero_uses (result)) |
ea65cd37 JL |
1045 | continue; |
1046 | ||
1047 | /* Get the single use of the result of this PHI node. */ | |
1048 | if (!single_imm_use (result, &imm_use, &use_stmt) | |
726a989a RB |
1049 | || gimple_code (use_stmt) != GIMPLE_PHI |
1050 | || gimple_bb (use_stmt) != dest | |
1051 | || gimple_phi_arg_def (use_stmt, dest_idx) != result) | |
ea65cd37 JL |
1052 | break; |
1053 | } | |
1054 | ||
c0220ea4 | 1055 | /* If the loop above iterated through all the PHI nodes |
ea65cd37 | 1056 | in BB, then we can merge the PHIs from BB into DEST. */ |
726a989a | 1057 | if (gsi_end_p (gsi)) |
ea65cd37 JL |
1058 | *current++ = bb; |
1059 | } | |
c9784e6d KH |
1060 | } |
1061 | ||
1062 | /* Now let's drain WORKLIST. */ | |
a9e0d843 | 1063 | bool changed = false; |
c9784e6d KH |
1064 | while (current != worklist) |
1065 | { | |
1066 | bb = *--current; | |
a9e0d843 | 1067 | changed |= remove_forwarder_block_with_phi (bb); |
c9784e6d | 1068 | } |
c9784e6d | 1069 | free (worklist); |
a9e0d843 RB |
1070 | |
1071 | /* Removing forwarder blocks can cause formerly irreducible loops | |
1072 | to become reducible if we merged two entry blocks. */ | |
1073 | if (changed | |
1074 | && current_loops) | |
1075 | loops_state_set (LOOPS_NEED_FIXUP); | |
1076 | ||
c2924966 | 1077 | return 0; |
c9784e6d KH |
1078 | } |
1079 | ||
27a4cd48 DM |
1080 | } // anon namespace |
1081 | ||
1082 | gimple_opt_pass * | |
1083 | make_pass_merge_phi (gcc::context *ctxt) | |
1084 | { | |
1085 | return new pass_merge_phi (ctxt); | |
1086 | } | |
4484a35a AM |
1087 | |
1088 | /* Pass: cleanup the CFG just before expanding trees to RTL. | |
1089 | This is just a round of label cleanups and case node grouping | |
1090 | because after the tree optimizers have run such cleanups may | |
1091 | be necessary. */ | |
1092 | ||
1093 | static unsigned int | |
1094 | execute_cleanup_cfg_post_optimizing (void) | |
1095 | { | |
1096 | unsigned int todo = 0; | |
1097 | if (cleanup_tree_cfg ()) | |
1098 | todo |= TODO_update_ssa; | |
1099 | maybe_remove_unreachable_handlers (); | |
1100 | cleanup_dead_labels (); | |
1101 | group_case_labels (); | |
1102 | if ((flag_compare_debug_opt || flag_compare_debug) | |
1103 | && flag_dump_final_insns) | |
1104 | { | |
1105 | FILE *final_output = fopen (flag_dump_final_insns, "a"); | |
1106 | ||
1107 | if (!final_output) | |
1108 | { | |
1109 | error ("could not open final insn dump file %qs: %m", | |
1110 | flag_dump_final_insns); | |
1111 | flag_dump_final_insns = NULL; | |
1112 | } | |
1113 | else | |
1114 | { | |
1115 | int save_unnumbered = flag_dump_unnumbered; | |
1116 | int save_noaddr = flag_dump_noaddr; | |
1117 | ||
1118 | flag_dump_noaddr = flag_dump_unnumbered = 1; | |
1119 | fprintf (final_output, "\n"); | |
1120 | dump_enumerated_decls (final_output, dump_flags | TDF_NOUID); | |
1121 | flag_dump_noaddr = save_noaddr; | |
1122 | flag_dump_unnumbered = save_unnumbered; | |
1123 | if (fclose (final_output)) | |
1124 | { | |
1125 | error ("could not close final insn dump file %qs: %m", | |
1126 | flag_dump_final_insns); | |
1127 | flag_dump_final_insns = NULL; | |
1128 | } | |
1129 | } | |
1130 | } | |
1131 | return todo; | |
1132 | } | |
1133 | ||
1134 | namespace { | |
1135 | ||
1136 | const pass_data pass_data_cleanup_cfg_post_optimizing = | |
1137 | { | |
1138 | GIMPLE_PASS, /* type */ | |
1139 | "optimized", /* name */ | |
1140 | OPTGROUP_NONE, /* optinfo_flags */ | |
4484a35a AM |
1141 | TV_TREE_CLEANUP_CFG, /* tv_id */ |
1142 | PROP_cfg, /* properties_required */ | |
1143 | 0, /* properties_provided */ | |
1144 | 0, /* properties_destroyed */ | |
1145 | 0, /* todo_flags_start */ | |
1146 | TODO_remove_unused_locals, /* todo_flags_finish */ | |
1147 | }; | |
1148 | ||
1149 | class pass_cleanup_cfg_post_optimizing : public gimple_opt_pass | |
1150 | { | |
1151 | public: | |
1152 | pass_cleanup_cfg_post_optimizing (gcc::context *ctxt) | |
1153 | : gimple_opt_pass (pass_data_cleanup_cfg_post_optimizing, ctxt) | |
1154 | {} | |
1155 | ||
1156 | /* opt_pass methods: */ | |
be55bfe6 TS |
1157 | virtual unsigned int execute (function *) |
1158 | { | |
1159 | return execute_cleanup_cfg_post_optimizing (); | |
1160 | } | |
4484a35a AM |
1161 | |
1162 | }; // class pass_cleanup_cfg_post_optimizing | |
1163 | ||
1164 | } // anon namespace | |
1165 | ||
1166 | gimple_opt_pass * | |
1167 | make_pass_cleanup_cfg_post_optimizing (gcc::context *ctxt) | |
1168 | { | |
1169 | return new pass_cleanup_cfg_post_optimizing (ctxt); | |
1170 | } | |
1171 | ||
1172 |