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6de9cd9a DN |
1 | /* Control flow functions for trees. |
2 | Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc. | |
3 | Contributed by Diego Novillo <dnovillo@redhat.com> | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License 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 | |
19 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
20 | Boston, MA 02111-1307, USA. */ | |
21 | ||
22 | #include "config.h" | |
23 | #include "system.h" | |
24 | #include "coretypes.h" | |
25 | #include "tm.h" | |
26 | #include "tree.h" | |
27 | #include "rtl.h" | |
28 | #include "tm_p.h" | |
29 | #include "hard-reg-set.h" | |
30 | #include "basic-block.h" | |
31 | #include "output.h" | |
32 | #include "errors.h" | |
33 | #include "flags.h" | |
34 | #include "function.h" | |
35 | #include "expr.h" | |
36 | #include "ggc.h" | |
37 | #include "langhooks.h" | |
38 | #include "diagnostic.h" | |
39 | #include "tree-flow.h" | |
40 | #include "timevar.h" | |
41 | #include "tree-dump.h" | |
42 | #include "tree-pass.h" | |
43 | #include "toplev.h" | |
44 | #include "except.h" | |
45 | #include "cfgloop.h" | |
46 | ||
47 | /* This file contains functions for building the Control Flow Graph (CFG) | |
48 | for a function tree. */ | |
49 | ||
50 | /* Local declarations. */ | |
51 | ||
52 | /* Initial capacity for the basic block array. */ | |
53 | static const int initial_cfg_capacity = 20; | |
54 | ||
55 | /* Mapping of labels to their associated blocks. This can greatly speed up | |
56 | building of the CFG in code with lots of gotos. */ | |
57 | static GTY(()) varray_type label_to_block_map; | |
58 | ||
59 | /* CFG statistics. */ | |
60 | struct cfg_stats_d | |
61 | { | |
62 | long num_merged_labels; | |
63 | }; | |
64 | ||
65 | static struct cfg_stats_d cfg_stats; | |
66 | ||
67 | /* Nonzero if we found a computed goto while building basic blocks. */ | |
68 | static bool found_computed_goto; | |
69 | ||
70 | /* Basic blocks and flowgraphs. */ | |
71 | static basic_block create_bb (void *, void *, basic_block); | |
72 | static void create_block_annotation (basic_block); | |
73 | static void free_blocks_annotations (void); | |
74 | static void clear_blocks_annotations (void); | |
75 | static void make_blocks (tree); | |
76 | static void factor_computed_gotos (void); | |
6de9cd9a DN |
77 | |
78 | /* Edges. */ | |
79 | static void make_edges (void); | |
80 | static void make_ctrl_stmt_edges (basic_block); | |
81 | static void make_exit_edges (basic_block); | |
82 | static void make_cond_expr_edges (basic_block); | |
83 | static void make_switch_expr_edges (basic_block); | |
84 | static void make_goto_expr_edges (basic_block); | |
85 | static edge tree_redirect_edge_and_branch (edge, basic_block); | |
86 | static edge tree_try_redirect_by_replacing_jump (edge, basic_block); | |
87 | static void split_critical_edges (void); | |
88 | ||
89 | /* Various helpers. */ | |
90 | static inline bool stmt_starts_bb_p (tree, tree); | |
91 | static int tree_verify_flow_info (void); | |
92 | static void tree_make_forwarder_block (edge); | |
93 | static bool thread_jumps (void); | |
94 | static bool tree_forwarder_block_p (basic_block); | |
95 | static void bsi_commit_edge_inserts_1 (edge e); | |
96 | static void tree_cfg2vcg (FILE *); | |
97 | ||
98 | /* Flowgraph optimization and cleanup. */ | |
99 | static void tree_merge_blocks (basic_block, basic_block); | |
100 | static bool tree_can_merge_blocks_p (basic_block, basic_block); | |
101 | static void remove_bb (basic_block); | |
f667741c | 102 | static void group_case_labels (void); |
6de9cd9a DN |
103 | static void cleanup_dead_labels (void); |
104 | static bool cleanup_control_flow (void); | |
105 | static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator); | |
106 | static edge find_taken_edge_cond_expr (basic_block, tree); | |
107 | static edge find_taken_edge_switch_expr (basic_block, tree); | |
108 | static tree find_case_label_for_value (tree, tree); | |
109 | static bool phi_alternatives_equal (basic_block, edge, edge); | |
110 | ||
111 | ||
112 | /*--------------------------------------------------------------------------- | |
113 | Create basic blocks | |
114 | ---------------------------------------------------------------------------*/ | |
115 | ||
116 | /* Entry point to the CFG builder for trees. TP points to the list of | |
117 | statements to be added to the flowgraph. */ | |
118 | ||
119 | static void | |
120 | build_tree_cfg (tree *tp) | |
121 | { | |
122 | /* Register specific tree functions. */ | |
123 | tree_register_cfg_hooks (); | |
124 | ||
125 | /* Initialize rbi_pool. */ | |
126 | alloc_rbi_pool (); | |
127 | ||
128 | /* Initialize the basic block array. */ | |
129 | init_flow (); | |
130 | n_basic_blocks = 0; | |
131 | last_basic_block = 0; | |
132 | VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info"); | |
133 | memset ((void *) &cfg_stats, 0, sizeof (cfg_stats)); | |
134 | ||
135 | /* Build a mapping of labels to their associated blocks. */ | |
136 | VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity, | |
137 | "label to block map"); | |
138 | ||
139 | ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR; | |
140 | EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR; | |
141 | ||
142 | found_computed_goto = 0; | |
143 | make_blocks (*tp); | |
144 | ||
145 | /* Computed gotos are hell to deal with, especially if there are | |
146 | lots of them with a large number of destinations. So we factor | |
147 | them to a common computed goto location before we build the | |
148 | edge list. After we convert back to normal form, we will un-factor | |
149 | the computed gotos since factoring introduces an unwanted jump. */ | |
150 | if (found_computed_goto) | |
151 | factor_computed_gotos (); | |
152 | ||
153 | /* Make sure there is always at least one block, even if its empty. */ | |
154 | if (n_basic_blocks == 0) | |
155 | create_empty_bb (ENTRY_BLOCK_PTR); | |
156 | ||
157 | create_block_annotation (ENTRY_BLOCK_PTR); | |
158 | create_block_annotation (EXIT_BLOCK_PTR); | |
159 | ||
160 | /* Adjust the size of the array. */ | |
161 | VARRAY_GROW (basic_block_info, n_basic_blocks); | |
162 | ||
f667741c SB |
163 | /* To speed up statement iterator walks, we first purge dead labels. */ |
164 | cleanup_dead_labels (); | |
165 | ||
166 | /* Group case nodes to reduce the number of edges. | |
167 | We do this after cleaning up dead labels because otherwise we miss | |
168 | a lot of obvious case merging opportunities. */ | |
169 | group_case_labels (); | |
170 | ||
6de9cd9a DN |
171 | /* Create the edges of the flowgraph. */ |
172 | make_edges (); | |
173 | ||
174 | /* Debugging dumps. */ | |
175 | ||
176 | /* Write the flowgraph to a VCG file. */ | |
177 | { | |
178 | int local_dump_flags; | |
179 | FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags); | |
180 | if (dump_file) | |
181 | { | |
182 | tree_cfg2vcg (dump_file); | |
183 | dump_end (TDI_vcg, dump_file); | |
184 | } | |
185 | } | |
186 | ||
187 | /* Dump a textual representation of the flowgraph. */ | |
188 | if (dump_file) | |
189 | dump_tree_cfg (dump_file, dump_flags); | |
190 | } | |
191 | ||
192 | static void | |
193 | execute_build_cfg (void) | |
194 | { | |
195 | build_tree_cfg (&DECL_SAVED_TREE (current_function_decl)); | |
196 | } | |
197 | ||
198 | struct tree_opt_pass pass_build_cfg = | |
199 | { | |
200 | "cfg", /* name */ | |
201 | NULL, /* gate */ | |
202 | execute_build_cfg, /* execute */ | |
203 | NULL, /* sub */ | |
204 | NULL, /* next */ | |
205 | 0, /* static_pass_number */ | |
206 | TV_TREE_CFG, /* tv_id */ | |
207 | PROP_gimple_leh, /* properties_required */ | |
208 | PROP_cfg, /* properties_provided */ | |
209 | 0, /* properties_destroyed */ | |
210 | 0, /* todo_flags_start */ | |
211 | TODO_verify_stmts /* todo_flags_finish */ | |
212 | }; | |
213 | ||
214 | /* Search the CFG for any computed gotos. If found, factor them to a | |
215 | common computed goto site. Also record the location of that site so | |
216 | that we can un-factor the gotos after we have converted back to | |
217 | normal form. */ | |
218 | ||
219 | static void | |
220 | factor_computed_gotos (void) | |
221 | { | |
222 | basic_block bb; | |
223 | tree factored_label_decl = NULL; | |
224 | tree var = NULL; | |
225 | tree factored_computed_goto_label = NULL; | |
226 | tree factored_computed_goto = NULL; | |
227 | ||
228 | /* We know there are one or more computed gotos in this function. | |
229 | Examine the last statement in each basic block to see if the block | |
230 | ends with a computed goto. */ | |
231 | ||
232 | FOR_EACH_BB (bb) | |
233 | { | |
234 | block_stmt_iterator bsi = bsi_last (bb); | |
235 | tree last; | |
236 | ||
237 | if (bsi_end_p (bsi)) | |
238 | continue; | |
239 | last = bsi_stmt (bsi); | |
240 | ||
241 | /* Ignore the computed goto we create when we factor the original | |
242 | computed gotos. */ | |
243 | if (last == factored_computed_goto) | |
244 | continue; | |
245 | ||
246 | /* If the last statement is a computed goto, factor it. */ | |
247 | if (computed_goto_p (last)) | |
248 | { | |
249 | tree assignment; | |
250 | ||
251 | /* The first time we find a computed goto we need to create | |
252 | the factored goto block and the variable each original | |
253 | computed goto will use for their goto destination. */ | |
254 | if (! factored_computed_goto) | |
255 | { | |
256 | basic_block new_bb = create_empty_bb (bb); | |
257 | block_stmt_iterator new_bsi = bsi_start (new_bb); | |
258 | ||
259 | /* Create the destination of the factored goto. Each original | |
260 | computed goto will put its desired destination into this | |
261 | variable and jump to the label we create immediately | |
262 | below. */ | |
263 | var = create_tmp_var (ptr_type_node, "gotovar"); | |
264 | ||
265 | /* Build a label for the new block which will contain the | |
266 | factored computed goto. */ | |
267 | factored_label_decl = create_artificial_label (); | |
268 | factored_computed_goto_label | |
269 | = build1 (LABEL_EXPR, void_type_node, factored_label_decl); | |
270 | bsi_insert_after (&new_bsi, factored_computed_goto_label, | |
271 | BSI_NEW_STMT); | |
272 | ||
273 | /* Build our new computed goto. */ | |
274 | factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var); | |
275 | bsi_insert_after (&new_bsi, factored_computed_goto, | |
276 | BSI_NEW_STMT); | |
277 | } | |
278 | ||
279 | /* Copy the original computed goto's destination into VAR. */ | |
280 | assignment = build (MODIFY_EXPR, ptr_type_node, | |
281 | var, GOTO_DESTINATION (last)); | |
282 | bsi_insert_before (&bsi, assignment, BSI_SAME_STMT); | |
283 | ||
284 | /* And re-vector the computed goto to the new destination. */ | |
285 | GOTO_DESTINATION (last) = factored_label_decl; | |
286 | } | |
287 | } | |
288 | } | |
289 | ||
290 | ||
291 | /* Create annotations for a single basic block. */ | |
292 | ||
293 | static void | |
294 | create_block_annotation (basic_block bb) | |
295 | { | |
296 | /* Verify that the tree_annotations field is clear. */ | |
297 | if (bb->tree_annotations) | |
298 | abort (); | |
299 | bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d)); | |
300 | } | |
301 | ||
302 | ||
303 | /* Free the annotations for all the basic blocks. */ | |
304 | ||
305 | static void free_blocks_annotations (void) | |
306 | { | |
307 | clear_blocks_annotations (); | |
308 | } | |
309 | ||
310 | ||
311 | /* Clear the annotations for all the basic blocks. */ | |
312 | ||
313 | static void | |
314 | clear_blocks_annotations (void) | |
315 | { | |
316 | basic_block bb; | |
317 | ||
318 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) | |
319 | bb->tree_annotations = NULL; | |
320 | } | |
321 | ||
322 | ||
323 | /* Build a flowgraph for the statement_list STMT_LIST. */ | |
324 | ||
325 | static void | |
326 | make_blocks (tree stmt_list) | |
327 | { | |
328 | tree_stmt_iterator i = tsi_start (stmt_list); | |
329 | tree stmt = NULL; | |
330 | bool start_new_block = true; | |
331 | bool first_stmt_of_list = true; | |
332 | basic_block bb = ENTRY_BLOCK_PTR; | |
333 | ||
334 | while (!tsi_end_p (i)) | |
335 | { | |
336 | tree prev_stmt; | |
337 | ||
338 | prev_stmt = stmt; | |
339 | stmt = tsi_stmt (i); | |
340 | ||
341 | /* If the statement starts a new basic block or if we have determined | |
342 | in a previous pass that we need to create a new block for STMT, do | |
343 | so now. */ | |
344 | if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt)) | |
345 | { | |
346 | if (!first_stmt_of_list) | |
347 | stmt_list = tsi_split_statement_list_before (&i); | |
348 | bb = create_basic_block (stmt_list, NULL, bb); | |
349 | start_new_block = false; | |
350 | } | |
351 | ||
352 | /* Now add STMT to BB and create the subgraphs for special statement | |
353 | codes. */ | |
354 | set_bb_for_stmt (stmt, bb); | |
355 | ||
356 | if (computed_goto_p (stmt)) | |
357 | found_computed_goto = true; | |
358 | ||
359 | /* If STMT is a basic block terminator, set START_NEW_BLOCK for the | |
360 | next iteration. */ | |
361 | if (stmt_ends_bb_p (stmt)) | |
362 | start_new_block = true; | |
363 | ||
364 | tsi_next (&i); | |
365 | first_stmt_of_list = false; | |
366 | } | |
367 | } | |
368 | ||
369 | ||
370 | /* Create and return a new empty basic block after bb AFTER. */ | |
371 | ||
372 | static basic_block | |
373 | create_bb (void *h, void *e, basic_block after) | |
374 | { | |
375 | basic_block bb; | |
376 | ||
377 | if (e) | |
378 | abort (); | |
379 | ||
380 | /* Create and initialize a new basic block. */ | |
381 | bb = alloc_block (); | |
382 | memset (bb, 0, sizeof (*bb)); | |
383 | ||
384 | bb->index = last_basic_block; | |
385 | bb->flags = BB_NEW; | |
386 | bb->stmt_list = h ? h : alloc_stmt_list (); | |
387 | ||
388 | /* Add the new block to the linked list of blocks. */ | |
389 | link_block (bb, after); | |
390 | ||
391 | /* Grow the basic block array if needed. */ | |
392 | if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info)) | |
393 | { | |
394 | size_t new_size = last_basic_block + (last_basic_block + 3) / 4; | |
395 | VARRAY_GROW (basic_block_info, new_size); | |
396 | } | |
397 | ||
398 | /* Add the newly created block to the array. */ | |
399 | BASIC_BLOCK (last_basic_block) = bb; | |
400 | ||
401 | create_block_annotation (bb); | |
402 | ||
403 | n_basic_blocks++; | |
404 | last_basic_block++; | |
405 | ||
406 | initialize_bb_rbi (bb); | |
407 | return bb; | |
408 | } | |
409 | ||
410 | ||
411 | /*--------------------------------------------------------------------------- | |
412 | Edge creation | |
413 | ---------------------------------------------------------------------------*/ | |
414 | ||
415 | /* Join all the blocks in the flowgraph. */ | |
416 | ||
417 | static void | |
418 | make_edges (void) | |
419 | { | |
420 | basic_block bb; | |
6de9cd9a DN |
421 | |
422 | /* Create an edge from entry to the first block with executable | |
423 | statements in it. */ | |
424 | make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU); | |
425 | ||
426 | /* Traverse basic block array placing edges. */ | |
427 | FOR_EACH_BB (bb) | |
428 | { | |
429 | tree first = first_stmt (bb); | |
430 | tree last = last_stmt (bb); | |
431 | ||
432 | if (first) | |
433 | { | |
434 | /* Edges for statements that always alter flow control. */ | |
435 | if (is_ctrl_stmt (last)) | |
436 | make_ctrl_stmt_edges (bb); | |
437 | ||
438 | /* Edges for statements that sometimes alter flow control. */ | |
439 | if (is_ctrl_altering_stmt (last)) | |
440 | make_exit_edges (bb); | |
441 | } | |
442 | ||
443 | /* Finally, if no edges were created above, this is a regular | |
444 | basic block that only needs a fallthru edge. */ | |
445 | if (bb->succ == NULL) | |
446 | make_edge (bb, bb->next_bb, EDGE_FALLTHRU); | |
447 | } | |
448 | ||
6de9cd9a DN |
449 | /* We do not care about fake edges, so remove any that the CFG |
450 | builder inserted for completeness. */ | |
451 | remove_fake_edges (); | |
452 | ||
6de9cd9a DN |
453 | /* Clean up the graph and warn for unreachable code. */ |
454 | cleanup_tree_cfg (); | |
455 | } | |
456 | ||
457 | ||
458 | /* Create edges for control statement at basic block BB. */ | |
459 | ||
460 | static void | |
461 | make_ctrl_stmt_edges (basic_block bb) | |
462 | { | |
463 | tree last = last_stmt (bb); | |
464 | tree first = first_stmt (bb); | |
465 | ||
466 | #if defined ENABLE_CHECKING | |
467 | if (last == NULL_TREE) | |
468 | abort(); | |
469 | #endif | |
470 | ||
471 | if (TREE_CODE (first) == LABEL_EXPR | |
472 | && DECL_NONLOCAL (LABEL_EXPR_LABEL (first))) | |
473 | make_edge (ENTRY_BLOCK_PTR, bb, EDGE_ABNORMAL); | |
474 | ||
475 | switch (TREE_CODE (last)) | |
476 | { | |
477 | case GOTO_EXPR: | |
478 | make_goto_expr_edges (bb); | |
479 | break; | |
480 | ||
481 | case RETURN_EXPR: | |
482 | make_edge (bb, EXIT_BLOCK_PTR, 0); | |
483 | break; | |
484 | ||
485 | case COND_EXPR: | |
486 | make_cond_expr_edges (bb); | |
487 | break; | |
488 | ||
489 | case SWITCH_EXPR: | |
490 | make_switch_expr_edges (bb); | |
491 | break; | |
492 | ||
493 | case RESX_EXPR: | |
494 | make_eh_edges (last); | |
495 | /* Yet another NORETURN hack. */ | |
496 | if (bb->succ == NULL) | |
497 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
498 | break; | |
499 | ||
500 | default: | |
501 | abort (); | |
502 | } | |
503 | } | |
504 | ||
505 | ||
506 | /* Create exit edges for statements in block BB that alter the flow of | |
507 | control. Statements that alter the control flow are 'goto', 'return' | |
508 | and calls to non-returning functions. */ | |
509 | ||
510 | static void | |
511 | make_exit_edges (basic_block bb) | |
512 | { | |
513 | tree last = last_stmt (bb); | |
514 | ||
515 | if (last == NULL_TREE) | |
516 | abort (); | |
517 | ||
518 | switch (TREE_CODE (last)) | |
519 | { | |
520 | case CALL_EXPR: | |
521 | /* If this function receives a nonlocal goto, then we need to | |
522 | make edges from this call site to all the nonlocal goto | |
523 | handlers. */ | |
524 | if (TREE_SIDE_EFFECTS (last) | |
525 | && current_function_has_nonlocal_label) | |
526 | make_goto_expr_edges (bb); | |
527 | ||
528 | /* If this statement has reachable exception handlers, then | |
529 | create abnormal edges to them. */ | |
530 | make_eh_edges (last); | |
531 | ||
532 | /* Some calls are known not to return. For such calls we create | |
533 | a fake edge. | |
534 | ||
535 | We really need to revamp how we build edges so that it's not | |
536 | such a bloody pain to avoid creating edges for this case since | |
537 | all we do is remove these edges when we're done building the | |
538 | CFG. */ | |
539 | if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP)) | |
540 | { | |
541 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
542 | return; | |
543 | } | |
544 | ||
545 | /* Don't forget the fall-thru edge. */ | |
546 | make_edge (bb, bb->next_bb, EDGE_FALLTHRU); | |
547 | break; | |
548 | ||
549 | case MODIFY_EXPR: | |
550 | /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR | |
551 | may have an abnormal edge. Search the RHS for this case and | |
552 | create any required edges. */ | |
553 | if (TREE_CODE (TREE_OPERAND (last, 1)) == CALL_EXPR | |
554 | && TREE_SIDE_EFFECTS (TREE_OPERAND (last, 1)) | |
555 | && current_function_has_nonlocal_label) | |
556 | make_goto_expr_edges (bb); | |
557 | ||
558 | make_eh_edges (last); | |
559 | make_edge (bb, bb->next_bb, EDGE_FALLTHRU); | |
560 | break; | |
561 | ||
562 | default: | |
563 | abort (); | |
564 | } | |
565 | } | |
566 | ||
567 | ||
568 | /* Create the edges for a COND_EXPR starting at block BB. | |
569 | At this point, both clauses must contain only simple gotos. */ | |
570 | ||
571 | static void | |
572 | make_cond_expr_edges (basic_block bb) | |
573 | { | |
574 | tree entry = last_stmt (bb); | |
575 | basic_block then_bb, else_bb; | |
576 | tree then_label, else_label; | |
577 | ||
578 | #if defined ENABLE_CHECKING | |
579 | if (entry == NULL_TREE || TREE_CODE (entry) != COND_EXPR) | |
580 | abort (); | |
581 | #endif | |
582 | ||
583 | /* Entry basic blocks for each component. */ | |
584 | then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry)); | |
585 | else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry)); | |
586 | then_bb = label_to_block (then_label); | |
587 | else_bb = label_to_block (else_label); | |
588 | ||
589 | make_edge (bb, then_bb, EDGE_TRUE_VALUE); | |
590 | make_edge (bb, else_bb, EDGE_FALSE_VALUE); | |
591 | } | |
592 | ||
593 | ||
594 | /* Create the edges for a SWITCH_EXPR starting at block BB. | |
595 | At this point, the switch body has been lowered and the | |
596 | SWITCH_LABELS filled in, so this is in effect a multi-way branch. */ | |
597 | ||
598 | static void | |
599 | make_switch_expr_edges (basic_block bb) | |
600 | { | |
601 | tree entry = last_stmt (bb); | |
602 | size_t i, n; | |
603 | tree vec; | |
604 | ||
605 | vec = SWITCH_LABELS (entry); | |
606 | n = TREE_VEC_LENGTH (vec); | |
607 | ||
608 | for (i = 0; i < n; ++i) | |
609 | { | |
610 | tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
611 | basic_block label_bb = label_to_block (lab); | |
612 | make_edge (bb, label_bb, 0); | |
613 | } | |
614 | } | |
615 | ||
616 | ||
617 | /* Return the basic block holding label DEST. */ | |
618 | ||
619 | basic_block | |
620 | label_to_block (tree dest) | |
621 | { | |
242229bb JH |
622 | int uid = LABEL_DECL_UID (dest); |
623 | ||
624 | /* We would die hard when faced by undefined label. Emit label to | |
625 | very first basic block. This will hopefully make even the dataflow | |
626 | and undefined variable warnings quite right. */ | |
627 | if ((errorcount || sorrycount) && uid < 0) | |
628 | { | |
629 | block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0)); | |
630 | tree stmt; | |
631 | ||
632 | stmt = build1 (LABEL_EXPR, void_type_node, dest); | |
633 | bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); | |
634 | uid = LABEL_DECL_UID (dest); | |
635 | } | |
636 | return VARRAY_BB (label_to_block_map, uid); | |
6de9cd9a DN |
637 | } |
638 | ||
639 | ||
640 | /* Create edges for a goto statement at block BB. */ | |
641 | ||
642 | static void | |
643 | make_goto_expr_edges (basic_block bb) | |
644 | { | |
645 | tree goto_t, dest; | |
646 | basic_block target_bb; | |
647 | int for_call; | |
648 | block_stmt_iterator last = bsi_last (bb); | |
649 | ||
650 | goto_t = bsi_stmt (last); | |
651 | ||
652 | /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR, | |
653 | CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting | |
654 | from a nonlocal goto. */ | |
655 | if (TREE_CODE (goto_t) != GOTO_EXPR) | |
656 | { | |
657 | dest = error_mark_node; | |
658 | for_call = 1; | |
659 | } | |
660 | else | |
661 | { | |
662 | dest = GOTO_DESTINATION (goto_t); | |
663 | for_call = 0; | |
664 | ||
665 | /* A GOTO to a local label creates normal edges. */ | |
666 | if (simple_goto_p (goto_t)) | |
667 | { | |
62b857ea RH |
668 | edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU); |
669 | e->goto_locus = EXPR_LOCUS (goto_t); | |
6de9cd9a DN |
670 | bsi_remove (&last); |
671 | return; | |
672 | } | |
673 | ||
9cf737f8 | 674 | /* Nothing more to do for nonlocal gotos. */ |
6de9cd9a DN |
675 | if (TREE_CODE (dest) == LABEL_DECL) |
676 | return; | |
677 | ||
678 | /* Computed gotos remain. */ | |
679 | } | |
680 | ||
681 | /* Look for the block starting with the destination label. In the | |
682 | case of a computed goto, make an edge to any label block we find | |
683 | in the CFG. */ | |
684 | FOR_EACH_BB (target_bb) | |
685 | { | |
686 | block_stmt_iterator bsi; | |
687 | ||
688 | for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
689 | { | |
690 | tree target = bsi_stmt (bsi); | |
691 | ||
692 | if (TREE_CODE (target) != LABEL_EXPR) | |
693 | break; | |
694 | ||
695 | if ( | |
696 | /* Computed GOTOs. Make an edge to every label block that has | |
697 | been marked as a potential target for a computed goto. */ | |
698 | (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0) | |
699 | /* Nonlocal GOTO target. Make an edge to every label block | |
700 | that has been marked as a potential target for a nonlocal | |
701 | goto. */ | |
702 | || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1)) | |
703 | { | |
704 | make_edge (bb, target_bb, EDGE_ABNORMAL); | |
705 | break; | |
706 | } | |
707 | } | |
708 | } | |
709 | ||
710 | /* Degenerate case of computed goto with no labels. */ | |
711 | if (!for_call && !bb->succ) | |
712 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
713 | } | |
714 | ||
715 | ||
716 | /*--------------------------------------------------------------------------- | |
717 | Flowgraph analysis | |
718 | ---------------------------------------------------------------------------*/ | |
719 | ||
720 | /* Remove unreachable blocks and other miscellaneous clean up work. */ | |
721 | ||
722 | void | |
723 | cleanup_tree_cfg (void) | |
724 | { | |
725 | bool something_changed = true; | |
726 | ||
727 | timevar_push (TV_TREE_CLEANUP_CFG); | |
728 | ||
729 | /* These three transformations can cascade, so we iterate on them until | |
730 | nothing changes. */ | |
731 | while (something_changed) | |
732 | { | |
733 | something_changed = cleanup_control_flow (); | |
734 | something_changed |= thread_jumps (); | |
735 | something_changed |= delete_unreachable_blocks (); | |
736 | } | |
737 | ||
738 | /* Merging the blocks creates no new opportunities for the other | |
739 | optimizations, so do it here. */ | |
740 | merge_seq_blocks (); | |
741 | ||
742 | compact_blocks (); | |
743 | ||
744 | #ifdef ENABLE_CHECKING | |
745 | verify_flow_info (); | |
746 | #endif | |
747 | timevar_pop (TV_TREE_CLEANUP_CFG); | |
748 | } | |
749 | ||
750 | ||
f698d217 SB |
751 | /* Cleanup useless labels in basic blocks. This is something we wish |
752 | to do early because it allows us to group case labels before creating | |
753 | the edges for the CFG, and it speeds up block statement iterators in | |
754 | all passes later on. | |
755 | We only run this pass once, running it more than once is probably not | |
756 | profitable. */ | |
757 | ||
758 | /* A map from basic block index to the leading label of that block. */ | |
759 | static tree *label_for_bb; | |
760 | ||
761 | /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */ | |
762 | static void | |
763 | update_eh_label (struct eh_region *region) | |
764 | { | |
765 | tree old_label = get_eh_region_tree_label (region); | |
766 | if (old_label) | |
767 | { | |
768 | tree new_label = label_for_bb[label_to_block (old_label)->index]; | |
769 | set_eh_region_tree_label (region, new_label); | |
770 | } | |
771 | } | |
772 | ||
242229bb JH |
773 | /* Given LABEL return the first label in the same basic block. */ |
774 | static tree | |
775 | main_block_label (tree label) | |
776 | { | |
777 | basic_block bb = label_to_block (label); | |
778 | ||
779 | /* label_to_block possibly inserted undefined label into the chain. */ | |
780 | if (!label_for_bb[bb->index]) | |
781 | label_for_bb[bb->index] = label; | |
782 | return label_for_bb[bb->index]; | |
783 | } | |
784 | ||
f698d217 SB |
785 | /* Cleanup redundant labels. This is a three-steo process: |
786 | 1) Find the leading label for each block. | |
787 | 2) Redirect all references to labels to the leading labels. | |
788 | 3) Cleanup all useless labels. */ | |
6de9cd9a DN |
789 | |
790 | static void | |
791 | cleanup_dead_labels (void) | |
792 | { | |
793 | basic_block bb; | |
f698d217 | 794 | label_for_bb = xcalloc (last_basic_block, sizeof (tree)); |
6de9cd9a DN |
795 | |
796 | /* Find a suitable label for each block. We use the first user-defined | |
797 | label is there is one, or otherwise just the first label we see. */ | |
798 | FOR_EACH_BB (bb) | |
799 | { | |
800 | block_stmt_iterator i; | |
801 | ||
802 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
803 | { | |
804 | tree label, stmt = bsi_stmt (i); | |
805 | ||
806 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
807 | break; | |
808 | ||
809 | label = LABEL_EXPR_LABEL (stmt); | |
810 | ||
811 | /* If we have not yet seen a label for the current block, | |
812 | remember this one and see if there are more labels. */ | |
813 | if (! label_for_bb[bb->index]) | |
814 | { | |
815 | label_for_bb[bb->index] = label; | |
816 | continue; | |
817 | } | |
818 | ||
819 | /* If we did see a label for the current block already, but it | |
820 | is an artificially created label, replace it if the current | |
821 | label is a user defined label. */ | |
822 | if (! DECL_ARTIFICIAL (label) | |
823 | && DECL_ARTIFICIAL (label_for_bb[bb->index])) | |
824 | { | |
825 | label_for_bb[bb->index] = label; | |
826 | break; | |
827 | } | |
828 | } | |
829 | } | |
830 | ||
f698d217 SB |
831 | /* Now redirect all jumps/branches to the selected label. |
832 | First do so for each block ending in a control statement. */ | |
6de9cd9a DN |
833 | FOR_EACH_BB (bb) |
834 | { | |
835 | tree stmt = last_stmt (bb); | |
836 | if (!stmt) | |
837 | continue; | |
838 | ||
839 | switch (TREE_CODE (stmt)) | |
840 | { | |
841 | case COND_EXPR: | |
842 | { | |
843 | tree true_branch, false_branch; | |
6de9cd9a DN |
844 | |
845 | true_branch = COND_EXPR_THEN (stmt); | |
846 | false_branch = COND_EXPR_ELSE (stmt); | |
6de9cd9a | 847 | |
242229bb JH |
848 | GOTO_DESTINATION (true_branch) |
849 | = main_block_label (GOTO_DESTINATION (true_branch)); | |
850 | GOTO_DESTINATION (false_branch) | |
851 | = main_block_label (GOTO_DESTINATION (false_branch)); | |
6de9cd9a DN |
852 | |
853 | break; | |
854 | } | |
855 | ||
856 | case SWITCH_EXPR: | |
857 | { | |
858 | size_t i; | |
859 | tree vec = SWITCH_LABELS (stmt); | |
860 | size_t n = TREE_VEC_LENGTH (vec); | |
861 | ||
862 | /* Replace all destination labels. */ | |
863 | for (i = 0; i < n; ++i) | |
242229bb JH |
864 | CASE_LABEL (TREE_VEC_ELT (vec, i)) |
865 | = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i))); | |
6de9cd9a DN |
866 | |
867 | break; | |
868 | } | |
869 | ||
f667741c SB |
870 | /* We have to handle GOTO_EXPRs until they're removed, and we don't |
871 | remove them until after we've created the CFG edges. */ | |
872 | case GOTO_EXPR: | |
242229bb JH |
873 | if (! computed_goto_p (stmt)) |
874 | { | |
875 | GOTO_DESTINATION (stmt) | |
876 | = main_block_label (GOTO_DESTINATION (stmt)); | |
877 | break; | |
878 | } | |
f667741c | 879 | |
6de9cd9a DN |
880 | default: |
881 | break; | |
882 | } | |
883 | } | |
884 | ||
f698d217 SB |
885 | for_each_eh_region (update_eh_label); |
886 | ||
6de9cd9a DN |
887 | /* Finally, purge dead labels. All user-defined labels and labels that |
888 | can be the target of non-local gotos are preserved. */ | |
889 | FOR_EACH_BB (bb) | |
890 | { | |
891 | block_stmt_iterator i; | |
892 | tree label_for_this_bb = label_for_bb[bb->index]; | |
893 | ||
894 | if (! label_for_this_bb) | |
895 | continue; | |
896 | ||
897 | for (i = bsi_start (bb); !bsi_end_p (i); ) | |
898 | { | |
899 | tree label, stmt = bsi_stmt (i); | |
900 | ||
901 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
902 | break; | |
903 | ||
904 | label = LABEL_EXPR_LABEL (stmt); | |
905 | ||
906 | if (label == label_for_this_bb | |
907 | || ! DECL_ARTIFICIAL (label) | |
908 | || DECL_NONLOCAL (label)) | |
909 | bsi_next (&i); | |
910 | else | |
911 | bsi_remove (&i); | |
912 | } | |
913 | } | |
914 | ||
915 | free (label_for_bb); | |
916 | } | |
917 | ||
f667741c SB |
918 | /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE), |
919 | and scan the sorted vector of cases. Combine the ones jumping to the | |
920 | same label. | |
921 | Eg. three separate entries 1: 2: 3: become one entry 1..3: */ | |
922 | ||
923 | static void | |
924 | group_case_labels (void) | |
925 | { | |
926 | basic_block bb; | |
927 | ||
928 | FOR_EACH_BB (bb) | |
929 | { | |
930 | tree stmt = last_stmt (bb); | |
931 | if (stmt && TREE_CODE (stmt) == SWITCH_EXPR) | |
932 | { | |
933 | tree labels = SWITCH_LABELS (stmt); | |
934 | int old_size = TREE_VEC_LENGTH (labels); | |
935 | int i, j, new_size = old_size; | |
936 | ||
937 | /* Look for possible opportunities to merge cases. | |
938 | Ignore the last element of the label vector because it | |
939 | must be the default case. */ | |
940 | i = 0; | |
941 | while (i < old_size - 2) | |
942 | { | |
943 | tree base_case, base_label, base_high, type; | |
944 | base_case = TREE_VEC_ELT (labels, i); | |
945 | ||
946 | if (! base_case) | |
947 | abort (); | |
948 | ||
949 | type = TREE_TYPE (CASE_LOW (base_case)); | |
950 | base_label = CASE_LABEL (base_case); | |
951 | base_high = CASE_HIGH (base_case) ? | |
952 | CASE_HIGH (base_case) : CASE_LOW (base_case); | |
953 | ||
954 | /* Try to merge case labels. Break out when we reach the end | |
955 | of the label vector or when we cannot merge the next case | |
956 | label with the current one. */ | |
957 | while (i < old_size - 2) | |
958 | { | |
959 | tree merge_case = TREE_VEC_ELT (labels, ++i); | |
960 | tree merge_label = CASE_LABEL (merge_case); | |
961 | tree t = int_const_binop (PLUS_EXPR, base_high, | |
962 | integer_one_node, 1); | |
963 | ||
964 | /* Merge the cases if they jump to the same place, | |
965 | and their ranges are consecutive. */ | |
966 | if (merge_label == base_label | |
967 | && tree_int_cst_equal (CASE_LOW (merge_case), t)) | |
968 | { | |
969 | base_high = CASE_HIGH (merge_case) ? | |
970 | CASE_HIGH (merge_case) : CASE_LOW (merge_case); | |
971 | CASE_HIGH (base_case) = base_high; | |
972 | TREE_VEC_ELT (labels, i) = NULL_TREE; | |
973 | new_size--; | |
974 | } | |
975 | else | |
976 | break; | |
977 | } | |
978 | } | |
979 | ||
980 | /* Compress the case labels in the label vector, and adjust the | |
981 | length of the vector. */ | |
982 | for (i = 0, j = 0; i < new_size; i++) | |
983 | { | |
984 | while (! TREE_VEC_ELT (labels, j)) | |
985 | j++; | |
986 | TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++); | |
987 | } | |
988 | TREE_VEC_LENGTH (labels) = new_size; | |
989 | } | |
990 | } | |
991 | } | |
6de9cd9a DN |
992 | |
993 | /* Checks whether we can merge block B into block A. */ | |
994 | ||
995 | static bool | |
996 | tree_can_merge_blocks_p (basic_block a, basic_block b) | |
997 | { | |
998 | tree stmt; | |
999 | block_stmt_iterator bsi; | |
1000 | ||
1001 | if (!a->succ | |
1002 | || a->succ->succ_next) | |
1003 | return false; | |
1004 | ||
1005 | if (a->succ->flags & EDGE_ABNORMAL) | |
1006 | return false; | |
1007 | ||
1008 | if (a->succ->dest != b) | |
1009 | return false; | |
1010 | ||
1011 | if (b == EXIT_BLOCK_PTR) | |
1012 | return false; | |
1013 | ||
1014 | if (b->pred->pred_next) | |
1015 | return false; | |
1016 | ||
1017 | /* If A ends by a statement causing exceptions or something similar, we | |
1018 | cannot merge the blocks. */ | |
1019 | stmt = last_stmt (a); | |
1020 | if (stmt && stmt_ends_bb_p (stmt)) | |
1021 | return false; | |
1022 | ||
1023 | /* Do not allow a block with only a non-local label to be merged. */ | |
1024 | if (stmt && TREE_CODE (stmt) == LABEL_EXPR | |
1025 | && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) | |
1026 | return false; | |
1027 | ||
1028 | /* There may be no phi nodes at the start of b. Most of these degenerate | |
1029 | phi nodes should be cleaned up by kill_redundant_phi_nodes. */ | |
1030 | if (phi_nodes (b)) | |
1031 | return false; | |
1032 | ||
1033 | /* Do not remove user labels. */ | |
1034 | for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi)) | |
1035 | { | |
1036 | stmt = bsi_stmt (bsi); | |
1037 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
1038 | break; | |
1039 | if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt))) | |
1040 | return false; | |
1041 | } | |
1042 | ||
1043 | return true; | |
1044 | } | |
1045 | ||
1046 | ||
1047 | /* Merge block B into block A. */ | |
1048 | ||
1049 | static void | |
1050 | tree_merge_blocks (basic_block a, basic_block b) | |
1051 | { | |
1052 | block_stmt_iterator bsi; | |
1053 | tree_stmt_iterator last; | |
1054 | ||
1055 | if (dump_file) | |
1056 | fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index); | |
1057 | ||
1058 | /* Ensure that B follows A. */ | |
1059 | move_block_after (b, a); | |
1060 | ||
1061 | if (!(a->succ->flags & EDGE_FALLTHRU)) | |
1062 | abort (); | |
1063 | ||
1064 | if (last_stmt (a) | |
1065 | && stmt_ends_bb_p (last_stmt (a))) | |
1066 | abort (); | |
1067 | ||
1068 | /* Remove labels from B and set bb_for_stmt to A for other statements. */ | |
1069 | for (bsi = bsi_start (b); !bsi_end_p (bsi);) | |
1070 | { | |
1071 | if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR) | |
1072 | bsi_remove (&bsi); | |
1073 | else | |
1074 | { | |
1075 | set_bb_for_stmt (bsi_stmt (bsi), a); | |
1076 | bsi_next (&bsi); | |
1077 | } | |
1078 | } | |
1079 | ||
1080 | /* Merge the chains. */ | |
1081 | last = tsi_last (a->stmt_list); | |
1082 | tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT); | |
1083 | b->stmt_list = NULL; | |
1084 | } | |
1085 | ||
1086 | ||
1087 | /* Walk the function tree removing unnecessary statements. | |
1088 | ||
1089 | * Empty statement nodes are removed | |
1090 | ||
1091 | * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed | |
1092 | ||
1093 | * Unnecessary COND_EXPRs are removed | |
1094 | ||
1095 | * Some unnecessary BIND_EXPRs are removed | |
1096 | ||
1097 | Clearly more work could be done. The trick is doing the analysis | |
1098 | and removal fast enough to be a net improvement in compile times. | |
1099 | ||
1100 | Note that when we remove a control structure such as a COND_EXPR | |
1101 | BIND_EXPR, or TRY block, we will need to repeat this optimization pass | |
1102 | to ensure we eliminate all the useless code. */ | |
1103 | ||
1104 | struct rus_data | |
1105 | { | |
1106 | tree *last_goto; | |
1107 | bool repeat; | |
1108 | bool may_throw; | |
1109 | bool may_branch; | |
1110 | bool has_label; | |
1111 | }; | |
1112 | ||
1113 | static void remove_useless_stmts_1 (tree *, struct rus_data *); | |
1114 | ||
1115 | static bool | |
1116 | remove_useless_stmts_warn_notreached (tree stmt) | |
1117 | { | |
1118 | if (EXPR_LOCUS (stmt)) | |
1119 | { | |
1120 | warning ("%Hwill never be executed", EXPR_LOCUS (stmt)); | |
1121 | return true; | |
1122 | } | |
1123 | ||
1124 | switch (TREE_CODE (stmt)) | |
1125 | { | |
1126 | case STATEMENT_LIST: | |
1127 | { | |
1128 | tree_stmt_iterator i; | |
1129 | for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i)) | |
1130 | if (remove_useless_stmts_warn_notreached (tsi_stmt (i))) | |
1131 | return true; | |
1132 | } | |
1133 | break; | |
1134 | ||
1135 | case COND_EXPR: | |
1136 | if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt))) | |
1137 | return true; | |
1138 | if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt))) | |
1139 | return true; | |
1140 | if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt))) | |
1141 | return true; | |
1142 | break; | |
1143 | ||
1144 | case TRY_FINALLY_EXPR: | |
1145 | case TRY_CATCH_EXPR: | |
1146 | if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0))) | |
1147 | return true; | |
1148 | if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1))) | |
1149 | return true; | |
1150 | break; | |
1151 | ||
1152 | case CATCH_EXPR: | |
1153 | return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt)); | |
1154 | case EH_FILTER_EXPR: | |
1155 | return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt)); | |
1156 | case BIND_EXPR: | |
1157 | return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt)); | |
1158 | ||
1159 | default: | |
1160 | /* Not a live container. */ | |
1161 | break; | |
1162 | } | |
1163 | ||
1164 | return false; | |
1165 | } | |
1166 | ||
1167 | static void | |
1168 | remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data) | |
1169 | { | |
1170 | tree then_clause, else_clause, cond; | |
1171 | bool save_has_label, then_has_label, else_has_label; | |
1172 | ||
1173 | save_has_label = data->has_label; | |
1174 | data->has_label = false; | |
1175 | data->last_goto = NULL; | |
1176 | ||
1177 | remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data); | |
1178 | ||
1179 | then_has_label = data->has_label; | |
1180 | data->has_label = false; | |
1181 | data->last_goto = NULL; | |
1182 | ||
1183 | remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data); | |
1184 | ||
1185 | else_has_label = data->has_label; | |
1186 | data->has_label = save_has_label | then_has_label | else_has_label; | |
1187 | ||
1188 | fold_stmt (stmt_p); | |
1189 | then_clause = COND_EXPR_THEN (*stmt_p); | |
1190 | else_clause = COND_EXPR_ELSE (*stmt_p); | |
1191 | cond = COND_EXPR_COND (*stmt_p); | |
1192 | ||
1193 | /* If neither arm does anything at all, we can remove the whole IF. */ | |
1194 | if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause)) | |
1195 | { | |
1196 | *stmt_p = build_empty_stmt (); | |
1197 | data->repeat = true; | |
1198 | } | |
1199 | ||
1200 | /* If there are no reachable statements in an arm, then we can | |
1201 | zap the entire conditional. */ | |
1202 | else if (integer_nonzerop (cond) && !else_has_label) | |
1203 | { | |
1204 | if (warn_notreached) | |
1205 | remove_useless_stmts_warn_notreached (else_clause); | |
1206 | *stmt_p = then_clause; | |
1207 | data->repeat = true; | |
1208 | } | |
1209 | else if (integer_zerop (cond) && !then_has_label) | |
1210 | { | |
1211 | if (warn_notreached) | |
1212 | remove_useless_stmts_warn_notreached (then_clause); | |
1213 | *stmt_p = else_clause; | |
1214 | data->repeat = true; | |
1215 | } | |
1216 | ||
1217 | /* Check a couple of simple things on then/else with single stmts. */ | |
1218 | else | |
1219 | { | |
1220 | tree then_stmt = expr_only (then_clause); | |
1221 | tree else_stmt = expr_only (else_clause); | |
1222 | ||
1223 | /* Notice branches to a common destination. */ | |
1224 | if (then_stmt && else_stmt | |
1225 | && TREE_CODE (then_stmt) == GOTO_EXPR | |
1226 | && TREE_CODE (else_stmt) == GOTO_EXPR | |
1227 | && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt))) | |
1228 | { | |
1229 | *stmt_p = then_stmt; | |
1230 | data->repeat = true; | |
1231 | } | |
1232 | ||
1233 | /* If the THEN/ELSE clause merely assigns a value to a variable or | |
1234 | parameter which is already known to contain that value, then | |
1235 | remove the useless THEN/ELSE clause. */ | |
1236 | else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL) | |
1237 | { | |
1238 | if (else_stmt | |
1239 | && TREE_CODE (else_stmt) == MODIFY_EXPR | |
1240 | && TREE_OPERAND (else_stmt, 0) == cond | |
1241 | && integer_zerop (TREE_OPERAND (else_stmt, 1))) | |
1242 | COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list (); | |
1243 | } | |
1244 | else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) | |
1245 | && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL | |
1246 | || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL) | |
1247 | && TREE_CONSTANT (TREE_OPERAND (cond, 1))) | |
1248 | { | |
1249 | tree stmt = (TREE_CODE (cond) == EQ_EXPR | |
1250 | ? then_stmt : else_stmt); | |
1251 | tree *location = (TREE_CODE (cond) == EQ_EXPR | |
1252 | ? &COND_EXPR_THEN (*stmt_p) | |
1253 | : &COND_EXPR_ELSE (*stmt_p)); | |
1254 | ||
1255 | if (stmt | |
1256 | && TREE_CODE (stmt) == MODIFY_EXPR | |
1257 | && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0) | |
1258 | && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1)) | |
1259 | *location = alloc_stmt_list (); | |
1260 | } | |
1261 | } | |
1262 | ||
1263 | /* Protect GOTOs in the arm of COND_EXPRs from being removed. They | |
1264 | would be re-introduced during lowering. */ | |
1265 | data->last_goto = NULL; | |
1266 | } | |
1267 | ||
1268 | ||
1269 | static void | |
1270 | remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data) | |
1271 | { | |
1272 | bool save_may_branch, save_may_throw; | |
1273 | bool this_may_branch, this_may_throw; | |
1274 | ||
1275 | /* Collect may_branch and may_throw information for the body only. */ | |
1276 | save_may_branch = data->may_branch; | |
1277 | save_may_throw = data->may_throw; | |
1278 | data->may_branch = false; | |
1279 | data->may_throw = false; | |
1280 | data->last_goto = NULL; | |
1281 | ||
1282 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); | |
1283 | ||
1284 | this_may_branch = data->may_branch; | |
1285 | this_may_throw = data->may_throw; | |
1286 | data->may_branch |= save_may_branch; | |
1287 | data->may_throw |= save_may_throw; | |
1288 | data->last_goto = NULL; | |
1289 | ||
1290 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); | |
1291 | ||
1292 | /* If the body is empty, then we can emit the FINALLY block without | |
1293 | the enclosing TRY_FINALLY_EXPR. */ | |
1294 | if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0))) | |
1295 | { | |
1296 | *stmt_p = TREE_OPERAND (*stmt_p, 1); | |
1297 | data->repeat = true; | |
1298 | } | |
1299 | ||
1300 | /* If the handler is empty, then we can emit the TRY block without | |
1301 | the enclosing TRY_FINALLY_EXPR. */ | |
1302 | else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) | |
1303 | { | |
1304 | *stmt_p = TREE_OPERAND (*stmt_p, 0); | |
1305 | data->repeat = true; | |
1306 | } | |
1307 | ||
1308 | /* If the body neither throws, nor branches, then we can safely | |
1309 | string the TRY and FINALLY blocks together. */ | |
1310 | else if (!this_may_branch && !this_may_throw) | |
1311 | { | |
1312 | tree stmt = *stmt_p; | |
1313 | *stmt_p = TREE_OPERAND (stmt, 0); | |
1314 | append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p); | |
1315 | data->repeat = true; | |
1316 | } | |
1317 | } | |
1318 | ||
1319 | ||
1320 | static void | |
1321 | remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data) | |
1322 | { | |
1323 | bool save_may_throw, this_may_throw; | |
1324 | tree_stmt_iterator i; | |
1325 | tree stmt; | |
1326 | ||
1327 | /* Collect may_throw information for the body only. */ | |
1328 | save_may_throw = data->may_throw; | |
1329 | data->may_throw = false; | |
1330 | data->last_goto = NULL; | |
1331 | ||
1332 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); | |
1333 | ||
1334 | this_may_throw = data->may_throw; | |
1335 | data->may_throw = save_may_throw; | |
1336 | ||
1337 | /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */ | |
1338 | if (!this_may_throw) | |
1339 | { | |
1340 | if (warn_notreached) | |
1341 | remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1)); | |
1342 | *stmt_p = TREE_OPERAND (*stmt_p, 0); | |
1343 | data->repeat = true; | |
1344 | return; | |
1345 | } | |
1346 | ||
1347 | /* Process the catch clause specially. We may be able to tell that | |
1348 | no exceptions propagate past this point. */ | |
1349 | ||
1350 | this_may_throw = true; | |
1351 | i = tsi_start (TREE_OPERAND (*stmt_p, 1)); | |
1352 | stmt = tsi_stmt (i); | |
1353 | data->last_goto = NULL; | |
1354 | ||
1355 | switch (TREE_CODE (stmt)) | |
1356 | { | |
1357 | case CATCH_EXPR: | |
1358 | for (; !tsi_end_p (i); tsi_next (&i)) | |
1359 | { | |
1360 | stmt = tsi_stmt (i); | |
1361 | /* If we catch all exceptions, then the body does not | |
1362 | propagate exceptions past this point. */ | |
1363 | if (CATCH_TYPES (stmt) == NULL) | |
1364 | this_may_throw = false; | |
1365 | data->last_goto = NULL; | |
1366 | remove_useless_stmts_1 (&CATCH_BODY (stmt), data); | |
1367 | } | |
1368 | break; | |
1369 | ||
1370 | case EH_FILTER_EXPR: | |
1371 | if (EH_FILTER_MUST_NOT_THROW (stmt)) | |
1372 | this_may_throw = false; | |
1373 | else if (EH_FILTER_TYPES (stmt) == NULL) | |
1374 | this_may_throw = false; | |
1375 | remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data); | |
1376 | break; | |
1377 | ||
1378 | default: | |
1379 | /* Otherwise this is a cleanup. */ | |
1380 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); | |
1381 | ||
1382 | /* If the cleanup is empty, then we can emit the TRY block without | |
1383 | the enclosing TRY_CATCH_EXPR. */ | |
1384 | if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) | |
1385 | { | |
1386 | *stmt_p = TREE_OPERAND (*stmt_p, 0); | |
1387 | data->repeat = true; | |
1388 | } | |
1389 | break; | |
1390 | } | |
1391 | data->may_throw |= this_may_throw; | |
1392 | } | |
1393 | ||
1394 | ||
1395 | static void | |
1396 | remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data) | |
1397 | { | |
1398 | tree block; | |
1399 | ||
1400 | /* First remove anything underneath the BIND_EXPR. */ | |
1401 | remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data); | |
1402 | ||
1403 | /* If the BIND_EXPR has no variables, then we can pull everything | |
1404 | up one level and remove the BIND_EXPR, unless this is the toplevel | |
1405 | BIND_EXPR for the current function or an inlined function. | |
1406 | ||
1407 | When this situation occurs we will want to apply this | |
1408 | optimization again. */ | |
1409 | block = BIND_EXPR_BLOCK (*stmt_p); | |
1410 | if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE | |
1411 | && *stmt_p != DECL_SAVED_TREE (current_function_decl) | |
1412 | && (! block | |
1413 | || ! BLOCK_ABSTRACT_ORIGIN (block) | |
1414 | || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block)) | |
1415 | != FUNCTION_DECL))) | |
1416 | { | |
1417 | *stmt_p = BIND_EXPR_BODY (*stmt_p); | |
1418 | data->repeat = true; | |
1419 | } | |
1420 | } | |
1421 | ||
1422 | ||
1423 | static void | |
1424 | remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data) | |
1425 | { | |
1426 | tree dest = GOTO_DESTINATION (*stmt_p); | |
1427 | ||
1428 | data->may_branch = true; | |
1429 | data->last_goto = NULL; | |
1430 | ||
1431 | /* Record the last goto expr, so that we can delete it if unnecessary. */ | |
1432 | if (TREE_CODE (dest) == LABEL_DECL) | |
1433 | data->last_goto = stmt_p; | |
1434 | } | |
1435 | ||
1436 | ||
1437 | static void | |
1438 | remove_useless_stmts_label (tree *stmt_p, struct rus_data *data) | |
1439 | { | |
1440 | tree label = LABEL_EXPR_LABEL (*stmt_p); | |
1441 | ||
1442 | data->has_label = true; | |
1443 | ||
1444 | /* We do want to jump across non-local label receiver code. */ | |
1445 | if (DECL_NONLOCAL (label)) | |
1446 | data->last_goto = NULL; | |
1447 | ||
1448 | else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label) | |
1449 | { | |
1450 | *data->last_goto = build_empty_stmt (); | |
1451 | data->repeat = true; | |
1452 | } | |
1453 | ||
1454 | /* ??? Add something here to delete unused labels. */ | |
1455 | } | |
1456 | ||
1457 | ||
1458 | /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its | |
1459 | decl. This allows us to eliminate redundant or useless | |
1460 | calls to "const" functions. | |
1461 | ||
1462 | Gimplifier already does the same operation, but we may notice functions | |
1463 | being const and pure once their calls has been gimplified, so we need | |
1464 | to update the flag. */ | |
1465 | ||
1466 | static void | |
1467 | update_call_expr_flags (tree call) | |
1468 | { | |
1469 | tree decl = get_callee_fndecl (call); | |
1470 | if (!decl) | |
1471 | return; | |
1472 | if (call_expr_flags (call) & (ECF_CONST | ECF_PURE)) | |
1473 | TREE_SIDE_EFFECTS (call) = 0; | |
1474 | if (TREE_NOTHROW (decl)) | |
1475 | TREE_NOTHROW (call) = 1; | |
1476 | } | |
1477 | ||
1478 | ||
1479 | /* T is CALL_EXPR. Set current_function_calls_* flags. */ | |
1480 | ||
1481 | void | |
1482 | notice_special_calls (tree t) | |
1483 | { | |
1484 | int flags = call_expr_flags (t); | |
1485 | ||
1486 | if (flags & ECF_MAY_BE_ALLOCA) | |
1487 | current_function_calls_alloca = true; | |
1488 | if (flags & ECF_RETURNS_TWICE) | |
1489 | current_function_calls_setjmp = true; | |
1490 | } | |
1491 | ||
1492 | ||
1493 | /* Clear flags set by notice_special_calls. Used by dead code removal | |
1494 | to update the flags. */ | |
1495 | ||
1496 | void | |
1497 | clear_special_calls (void) | |
1498 | { | |
1499 | current_function_calls_alloca = false; | |
1500 | current_function_calls_setjmp = false; | |
1501 | } | |
1502 | ||
1503 | ||
1504 | static void | |
1505 | remove_useless_stmts_1 (tree *tp, struct rus_data *data) | |
1506 | { | |
1507 | tree t = *tp; | |
1508 | ||
1509 | switch (TREE_CODE (t)) | |
1510 | { | |
1511 | case COND_EXPR: | |
1512 | remove_useless_stmts_cond (tp, data); | |
1513 | break; | |
1514 | ||
1515 | case TRY_FINALLY_EXPR: | |
1516 | remove_useless_stmts_tf (tp, data); | |
1517 | break; | |
1518 | ||
1519 | case TRY_CATCH_EXPR: | |
1520 | remove_useless_stmts_tc (tp, data); | |
1521 | break; | |
1522 | ||
1523 | case BIND_EXPR: | |
1524 | remove_useless_stmts_bind (tp, data); | |
1525 | break; | |
1526 | ||
1527 | case GOTO_EXPR: | |
1528 | remove_useless_stmts_goto (tp, data); | |
1529 | break; | |
1530 | ||
1531 | case LABEL_EXPR: | |
1532 | remove_useless_stmts_label (tp, data); | |
1533 | break; | |
1534 | ||
1535 | case RETURN_EXPR: | |
1536 | fold_stmt (tp); | |
1537 | data->last_goto = NULL; | |
1538 | data->may_branch = true; | |
1539 | break; | |
1540 | ||
1541 | case CALL_EXPR: | |
1542 | fold_stmt (tp); | |
1543 | data->last_goto = NULL; | |
1544 | notice_special_calls (t); | |
1545 | update_call_expr_flags (t); | |
1546 | if (tree_could_throw_p (t)) | |
1547 | data->may_throw = true; | |
1548 | break; | |
1549 | ||
1550 | case MODIFY_EXPR: | |
1551 | data->last_goto = NULL; | |
1552 | fold_stmt (tp); | |
1553 | if (TREE_CODE (TREE_OPERAND (t, 1)) == CALL_EXPR) | |
1554 | { | |
1555 | update_call_expr_flags (TREE_OPERAND (t, 1)); | |
1556 | notice_special_calls (TREE_OPERAND (t, 1)); | |
1557 | } | |
1558 | if (tree_could_throw_p (t)) | |
1559 | data->may_throw = true; | |
1560 | break; | |
1561 | ||
1562 | case STATEMENT_LIST: | |
1563 | { | |
1564 | tree_stmt_iterator i = tsi_start (t); | |
1565 | while (!tsi_end_p (i)) | |
1566 | { | |
1567 | t = tsi_stmt (i); | |
1568 | if (IS_EMPTY_STMT (t)) | |
1569 | { | |
1570 | tsi_delink (&i); | |
1571 | continue; | |
1572 | } | |
1573 | ||
1574 | remove_useless_stmts_1 (tsi_stmt_ptr (i), data); | |
1575 | ||
1576 | t = tsi_stmt (i); | |
1577 | if (TREE_CODE (t) == STATEMENT_LIST) | |
1578 | { | |
1579 | tsi_link_before (&i, t, TSI_SAME_STMT); | |
1580 | tsi_delink (&i); | |
1581 | } | |
1582 | else | |
1583 | tsi_next (&i); | |
1584 | } | |
1585 | } | |
1586 | break; | |
1587 | case SWITCH_EXPR: | |
1588 | fold_stmt (tp); | |
1589 | data->last_goto = NULL; | |
1590 | break; | |
1591 | ||
1592 | default: | |
1593 | data->last_goto = NULL; | |
1594 | break; | |
1595 | } | |
1596 | } | |
1597 | ||
1598 | static void | |
1599 | remove_useless_stmts (void) | |
1600 | { | |
1601 | struct rus_data data; | |
1602 | ||
1603 | clear_special_calls (); | |
1604 | ||
1605 | do | |
1606 | { | |
1607 | memset (&data, 0, sizeof (data)); | |
1608 | remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data); | |
1609 | } | |
1610 | while (data.repeat); | |
1611 | } | |
1612 | ||
1613 | ||
1614 | struct tree_opt_pass pass_remove_useless_stmts = | |
1615 | { | |
1616 | "useless", /* name */ | |
1617 | NULL, /* gate */ | |
1618 | remove_useless_stmts, /* execute */ | |
1619 | NULL, /* sub */ | |
1620 | NULL, /* next */ | |
1621 | 0, /* static_pass_number */ | |
1622 | 0, /* tv_id */ | |
1623 | PROP_gimple_any, /* properties_required */ | |
1624 | 0, /* properties_provided */ | |
1625 | 0, /* properties_destroyed */ | |
1626 | 0, /* todo_flags_start */ | |
1627 | TODO_dump_func /* todo_flags_finish */ | |
1628 | }; | |
1629 | ||
1630 | ||
1631 | /* Remove obviously useless statements in basic block BB. */ | |
1632 | ||
1633 | static void | |
1634 | cfg_remove_useless_stmts_bb (basic_block bb) | |
1635 | { | |
1636 | block_stmt_iterator bsi; | |
1637 | tree stmt = NULL_TREE; | |
1638 | tree cond, var = NULL_TREE, val = NULL_TREE; | |
1639 | struct var_ann_d *ann; | |
1640 | ||
1641 | /* Check whether we come here from a condition, and if so, get the | |
1642 | condition. */ | |
1643 | if (!bb->pred | |
1644 | || bb->pred->pred_next | |
1645 | || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
1646 | return; | |
1647 | ||
1648 | cond = COND_EXPR_COND (last_stmt (bb->pred->src)); | |
1649 | ||
1650 | if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL) | |
1651 | { | |
1652 | var = cond; | |
1653 | val = (bb->pred->flags & EDGE_FALSE_VALUE | |
1654 | ? boolean_false_node : boolean_true_node); | |
1655 | } | |
1656 | else if (TREE_CODE (cond) == TRUTH_NOT_EXPR | |
1657 | && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL | |
1658 | || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)) | |
1659 | { | |
1660 | var = TREE_OPERAND (cond, 0); | |
1661 | val = (bb->pred->flags & EDGE_FALSE_VALUE | |
1662 | ? boolean_true_node : boolean_false_node); | |
1663 | } | |
1664 | else | |
1665 | { | |
1666 | if (bb->pred->flags & EDGE_FALSE_VALUE) | |
1667 | cond = invert_truthvalue (cond); | |
1668 | if (TREE_CODE (cond) == EQ_EXPR | |
1669 | && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL | |
1670 | || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL) | |
1671 | && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL | |
1672 | || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL | |
1673 | || TREE_CONSTANT (TREE_OPERAND (cond, 1)))) | |
1674 | { | |
1675 | var = TREE_OPERAND (cond, 0); | |
1676 | val = TREE_OPERAND (cond, 1); | |
1677 | } | |
1678 | else | |
1679 | return; | |
1680 | } | |
1681 | ||
1682 | /* Only work for normal local variables. */ | |
1683 | ann = var_ann (var); | |
1684 | if (!ann | |
1685 | || ann->may_aliases | |
1686 | || TREE_ADDRESSABLE (var)) | |
1687 | return; | |
1688 | ||
1689 | if (! TREE_CONSTANT (val)) | |
1690 | { | |
1691 | ann = var_ann (val); | |
1692 | if (!ann | |
1693 | || ann->may_aliases | |
1694 | || TREE_ADDRESSABLE (val)) | |
1695 | return; | |
1696 | } | |
1697 | ||
1698 | /* Ignore floating point variables, since comparison behaves weird for | |
1699 | them. */ | |
1700 | if (FLOAT_TYPE_P (TREE_TYPE (var))) | |
1701 | return; | |
1702 | ||
1703 | for (bsi = bsi_start (bb); !bsi_end_p (bsi);) | |
1704 | { | |
1705 | stmt = bsi_stmt (bsi); | |
1706 | ||
1707 | /* If the THEN/ELSE clause merely assigns a value to a variable/parameter | |
1708 | which is already known to contain that value, then remove the useless | |
1709 | THEN/ELSE clause. */ | |
1710 | if (TREE_CODE (stmt) == MODIFY_EXPR | |
1711 | && TREE_OPERAND (stmt, 0) == var | |
1712 | && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0)) | |
1713 | { | |
1714 | bsi_remove (&bsi); | |
1715 | continue; | |
1716 | } | |
1717 | ||
1718 | /* Invalidate the var if we encounter something that could modify it. */ | |
1719 | if (TREE_CODE (stmt) == ASM_EXPR | |
1720 | || TREE_CODE (stmt) == VA_ARG_EXPR | |
1721 | || (TREE_CODE (stmt) == MODIFY_EXPR | |
1722 | && (TREE_OPERAND (stmt, 0) == var | |
1723 | || TREE_OPERAND (stmt, 0) == val | |
1724 | || TREE_CODE (TREE_OPERAND (stmt, 1)) == VA_ARG_EXPR))) | |
1725 | return; | |
1726 | ||
1727 | bsi_next (&bsi); | |
1728 | } | |
1729 | } | |
1730 | ||
1731 | ||
1732 | /* A CFG-aware version of remove_useless_stmts. */ | |
1733 | ||
1734 | void | |
1735 | cfg_remove_useless_stmts (void) | |
1736 | { | |
1737 | basic_block bb; | |
1738 | ||
1739 | #ifdef ENABLE_CHECKING | |
1740 | verify_flow_info (); | |
1741 | #endif | |
1742 | ||
1743 | FOR_EACH_BB (bb) | |
1744 | { | |
1745 | cfg_remove_useless_stmts_bb (bb); | |
1746 | } | |
1747 | } | |
1748 | ||
1749 | ||
1750 | /* Remove PHI nodes associated with basic block BB and all edges out of BB. */ | |
1751 | ||
1752 | static void | |
1753 | remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb) | |
1754 | { | |
1755 | tree phi; | |
1756 | ||
1757 | /* Since this block is no longer reachable, we can just delete all | |
1758 | of its PHI nodes. */ | |
1759 | phi = phi_nodes (bb); | |
1760 | while (phi) | |
1761 | { | |
17192884 | 1762 | tree next = PHI_CHAIN (phi); |
6de9cd9a DN |
1763 | remove_phi_node (phi, NULL_TREE, bb); |
1764 | phi = next; | |
1765 | } | |
1766 | ||
1767 | /* Remove edges to BB's successors. */ | |
1768 | while (bb->succ != NULL) | |
1769 | ssa_remove_edge (bb->succ); | |
1770 | } | |
1771 | ||
1772 | ||
1773 | /* Remove statements of basic block BB. */ | |
1774 | ||
1775 | static void | |
1776 | remove_bb (basic_block bb) | |
1777 | { | |
1778 | block_stmt_iterator i; | |
1779 | location_t *loc = NULL; | |
1780 | ||
1781 | if (dump_file) | |
1782 | { | |
1783 | fprintf (dump_file, "Removing basic block %d\n", bb->index); | |
1784 | if (dump_flags & TDF_DETAILS) | |
1785 | { | |
1786 | dump_bb (bb, dump_file, 0); | |
1787 | fprintf (dump_file, "\n"); | |
1788 | } | |
1789 | } | |
1790 | ||
1791 | /* Remove all the instructions in the block. */ | |
1792 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i)) | |
1793 | { | |
1794 | tree stmt = bsi_stmt (i); | |
1795 | ||
1796 | set_bb_for_stmt (stmt, NULL); | |
1797 | ||
1798 | /* Don't warn for removed gotos. Gotos are often removed due to | |
1799 | jump threading, thus resulting in bogus warnings. Not great, | |
1800 | since this way we lose warnings for gotos in the original | |
1801 | program that are indeed unreachable. */ | |
1802 | if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_LOCUS (stmt) && !loc) | |
1803 | loc = EXPR_LOCUS (stmt); | |
1804 | } | |
1805 | ||
1806 | /* If requested, give a warning that the first statement in the | |
1807 | block is unreachable. We walk statements backwards in the | |
1808 | loop above, so the last statement we process is the first statement | |
1809 | in the block. */ | |
1810 | if (warn_notreached && loc) | |
1811 | warning ("%Hwill never be executed", loc); | |
1812 | ||
1813 | remove_phi_nodes_and_edges_for_unreachable_block (bb); | |
1814 | } | |
1815 | ||
1816 | ||
1817 | /* Examine BB to determine if it is a forwarding block (a block which only | |
1818 | transfers control to a new destination). If BB is a forwarding block, | |
1819 | then return the edge leading to the ultimate destination. */ | |
1820 | ||
1821 | edge | |
1822 | tree_block_forwards_to (basic_block bb) | |
1823 | { | |
1824 | block_stmt_iterator bsi; | |
1825 | bb_ann_t ann = bb_ann (bb); | |
1826 | tree stmt; | |
1827 | ||
1828 | /* If this block is not forwardable, then avoid useless work. */ | |
1829 | if (! ann->forwardable) | |
1830 | return NULL; | |
1831 | ||
1832 | /* Set this block to not be forwardable. This prevents infinite loops since | |
1833 | any block currently under examination is considered non-forwardable. */ | |
1834 | ann->forwardable = 0; | |
1835 | ||
1836 | /* No forwarding is possible if this block is a special block (ENTRY/EXIT), | |
1837 | this block has more than one successor, this block's single successor is | |
1838 | reached via an abnormal edge, this block has phi nodes, or this block's | |
1839 | single successor has phi nodes. */ | |
1840 | if (bb == EXIT_BLOCK_PTR | |
1841 | || bb == ENTRY_BLOCK_PTR | |
1842 | || !bb->succ | |
1843 | || bb->succ->succ_next | |
1844 | || bb->succ->dest == EXIT_BLOCK_PTR | |
1845 | || (bb->succ->flags & EDGE_ABNORMAL) != 0 | |
1846 | || phi_nodes (bb) | |
1847 | || phi_nodes (bb->succ->dest)) | |
1848 | return NULL; | |
1849 | ||
1850 | /* Walk past any labels at the start of this block. */ | |
1851 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
1852 | { | |
1853 | stmt = bsi_stmt (bsi); | |
1854 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
1855 | break; | |
1856 | } | |
1857 | ||
1858 | /* If we reached the end of this block we may be able to optimize this | |
1859 | case. */ | |
1860 | if (bsi_end_p (bsi)) | |
1861 | { | |
1862 | edge dest; | |
1863 | ||
1864 | /* Recursive call to pick up chains of forwarding blocks. */ | |
1865 | dest = tree_block_forwards_to (bb->succ->dest); | |
1866 | ||
1867 | /* If none found, we forward to bb->succ at minimum. */ | |
1868 | if (!dest) | |
1869 | dest = bb->succ; | |
1870 | ||
1871 | ann->forwardable = 1; | |
1872 | return dest; | |
1873 | } | |
1874 | ||
1875 | /* No forwarding possible. */ | |
1876 | return NULL; | |
1877 | } | |
1878 | ||
1879 | ||
1880 | /* Try to remove superfluous control structures. */ | |
1881 | ||
1882 | static bool | |
1883 | cleanup_control_flow (void) | |
1884 | { | |
1885 | basic_block bb; | |
1886 | block_stmt_iterator bsi; | |
1887 | bool retval = false; | |
1888 | tree stmt; | |
1889 | ||
1890 | FOR_EACH_BB (bb) | |
1891 | { | |
1892 | bsi = bsi_last (bb); | |
1893 | ||
1894 | if (bsi_end_p (bsi)) | |
1895 | continue; | |
1896 | ||
1897 | stmt = bsi_stmt (bsi); | |
1898 | if (TREE_CODE (stmt) == COND_EXPR | |
1899 | || TREE_CODE (stmt) == SWITCH_EXPR) | |
1900 | retval |= cleanup_control_expr_graph (bb, bsi); | |
1901 | } | |
1902 | return retval; | |
1903 | } | |
1904 | ||
1905 | ||
1906 | /* Disconnect an unreachable block in the control expression starting | |
1907 | at block BB. */ | |
1908 | ||
1909 | static bool | |
1910 | cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi) | |
1911 | { | |
1912 | edge taken_edge; | |
1913 | bool retval = false; | |
1914 | tree expr = bsi_stmt (bsi), val; | |
1915 | ||
1916 | if (bb->succ->succ_next) | |
1917 | { | |
1918 | edge e, next; | |
1919 | ||
1920 | switch (TREE_CODE (expr)) | |
1921 | { | |
1922 | case COND_EXPR: | |
1923 | val = COND_EXPR_COND (expr); | |
1924 | break; | |
1925 | ||
1926 | case SWITCH_EXPR: | |
1927 | val = SWITCH_COND (expr); | |
1928 | if (TREE_CODE (val) != INTEGER_CST) | |
1929 | return false; | |
1930 | break; | |
1931 | ||
1932 | default: | |
1933 | abort (); | |
1934 | } | |
1935 | ||
1936 | taken_edge = find_taken_edge (bb, val); | |
1937 | if (!taken_edge) | |
1938 | return false; | |
1939 | ||
1940 | /* Remove all the edges except the one that is always executed. */ | |
1941 | for (e = bb->succ; e; e = next) | |
1942 | { | |
1943 | next = e->succ_next; | |
1944 | if (e != taken_edge) | |
1945 | { | |
1946 | taken_edge->probability += e->probability; | |
1947 | taken_edge->count += e->count; | |
1948 | ssa_remove_edge (e); | |
1949 | retval = true; | |
1950 | } | |
1951 | } | |
1952 | if (taken_edge->probability > REG_BR_PROB_BASE) | |
1953 | taken_edge->probability = REG_BR_PROB_BASE; | |
1954 | } | |
1955 | else | |
1956 | taken_edge = bb->succ; | |
1957 | ||
1958 | bsi_remove (&bsi); | |
1959 | taken_edge->flags = EDGE_FALLTHRU; | |
1960 | ||
1961 | /* We removed some paths from the cfg. */ | |
1962 | if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK) | |
1963 | dom_computed[CDI_DOMINATORS] = DOM_CONS_OK; | |
1964 | ||
1965 | return retval; | |
1966 | } | |
1967 | ||
1968 | ||
1969 | /* Given a control block BB and a constant value VAL, return the edge that | |
1970 | will be taken out of the block. If VAL does not match a unique edge, | |
1971 | NULL is returned. */ | |
1972 | ||
1973 | edge | |
1974 | find_taken_edge (basic_block bb, tree val) | |
1975 | { | |
1976 | tree stmt; | |
1977 | ||
1978 | stmt = last_stmt (bb); | |
1979 | ||
1980 | #if defined ENABLE_CHECKING | |
1981 | if (stmt == NULL_TREE || !is_ctrl_stmt (stmt)) | |
1982 | abort (); | |
1983 | #endif | |
1984 | ||
1985 | /* If VAL is not a constant, we can't determine which edge might | |
1986 | be taken. */ | |
1987 | if (val == NULL || !really_constant_p (val)) | |
1988 | return NULL; | |
1989 | ||
1990 | if (TREE_CODE (stmt) == COND_EXPR) | |
1991 | return find_taken_edge_cond_expr (bb, val); | |
1992 | ||
1993 | if (TREE_CODE (stmt) == SWITCH_EXPR) | |
1994 | return find_taken_edge_switch_expr (bb, val); | |
1995 | ||
1996 | return bb->succ; | |
1997 | } | |
1998 | ||
1999 | ||
2000 | /* Given a constant value VAL and the entry block BB to a COND_EXPR | |
2001 | statement, determine which of the two edges will be taken out of the | |
2002 | block. Return NULL if either edge may be taken. */ | |
2003 | ||
2004 | static edge | |
2005 | find_taken_edge_cond_expr (basic_block bb, tree val) | |
2006 | { | |
2007 | edge true_edge, false_edge; | |
2008 | ||
2009 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
2010 | ||
2011 | /* If both edges of the branch lead to the same basic block, it doesn't | |
2012 | matter which edge is taken. */ | |
2013 | if (true_edge->dest == false_edge->dest) | |
2014 | return true_edge; | |
2015 | ||
2016 | /* Otherwise, try to determine which branch of the if() will be taken. | |
2017 | If VAL is a constant but it can't be reduced to a 0 or a 1, then | |
2018 | we don't really know which edge will be taken at runtime. This | |
2019 | may happen when comparing addresses (e.g., if (&var1 == 4)). */ | |
2020 | if (integer_nonzerop (val)) | |
2021 | return true_edge; | |
2022 | else if (integer_zerop (val)) | |
2023 | return false_edge; | |
2024 | else | |
2025 | return NULL; | |
2026 | } | |
2027 | ||
2028 | ||
2029 | /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR | |
2030 | statement, determine which edge will be taken out of the block. Return | |
2031 | NULL if any edge may be taken. */ | |
2032 | ||
2033 | static edge | |
2034 | find_taken_edge_switch_expr (basic_block bb, tree val) | |
2035 | { | |
2036 | tree switch_expr, taken_case; | |
2037 | basic_block dest_bb; | |
2038 | edge e; | |
2039 | ||
2040 | if (TREE_CODE (val) != INTEGER_CST) | |
2041 | return NULL; | |
2042 | ||
2043 | switch_expr = last_stmt (bb); | |
2044 | taken_case = find_case_label_for_value (switch_expr, val); | |
2045 | dest_bb = label_to_block (CASE_LABEL (taken_case)); | |
2046 | ||
2047 | e = find_edge (bb, dest_bb); | |
2048 | if (!e) | |
2049 | abort (); | |
2050 | return e; | |
2051 | } | |
2052 | ||
2053 | ||
f667741c SB |
2054 | /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL. |
2055 | We can make optimal use here of the fact that the case labels are | |
2056 | sorted: We can do a binary search for a case matching VAL. */ | |
6de9cd9a DN |
2057 | |
2058 | static tree | |
2059 | find_case_label_for_value (tree switch_expr, tree val) | |
2060 | { | |
2061 | tree vec = SWITCH_LABELS (switch_expr); | |
f667741c SB |
2062 | size_t low, high, n = TREE_VEC_LENGTH (vec); |
2063 | tree default_case = TREE_VEC_ELT (vec, n - 1); | |
6de9cd9a | 2064 | |
f667741c | 2065 | for (low = -1, high = n - 1; high - low > 1; ) |
6de9cd9a | 2066 | { |
f667741c | 2067 | size_t i = (high + low) / 2; |
6de9cd9a | 2068 | tree t = TREE_VEC_ELT (vec, i); |
f667741c SB |
2069 | int cmp; |
2070 | ||
2071 | /* Cache the result of comparing CASE_LOW and val. */ | |
2072 | cmp = tree_int_cst_compare (CASE_LOW (t), val); | |
6de9cd9a | 2073 | |
f667741c SB |
2074 | if (cmp > 0) |
2075 | high = i; | |
2076 | else | |
2077 | low = i; | |
2078 | ||
2079 | if (CASE_HIGH (t) == NULL) | |
6de9cd9a | 2080 | { |
f667741c SB |
2081 | /* A singe-valued case label. */ |
2082 | if (cmp == 0) | |
6de9cd9a DN |
2083 | return t; |
2084 | } | |
2085 | else | |
2086 | { | |
2087 | /* A case range. We can only handle integer ranges. */ | |
f667741c | 2088 | if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0) |
6de9cd9a DN |
2089 | return t; |
2090 | } | |
2091 | } | |
2092 | ||
6de9cd9a DN |
2093 | return default_case; |
2094 | } | |
2095 | ||
2096 | ||
2097 | /* If all the PHI nodes in DEST have alternatives for E1 and E2 and | |
2098 | those alternatives are equal in each of the PHI nodes, then return | |
2099 | true, else return false. */ | |
2100 | ||
2101 | static bool | |
2102 | phi_alternatives_equal (basic_block dest, edge e1, edge e2) | |
2103 | { | |
2104 | tree phi, val1, val2; | |
2105 | int n1, n2; | |
2106 | ||
17192884 | 2107 | for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
2108 | { |
2109 | n1 = phi_arg_from_edge (phi, e1); | |
2110 | n2 = phi_arg_from_edge (phi, e2); | |
2111 | ||
2112 | #ifdef ENABLE_CHECKING | |
2113 | if (n1 < 0 || n2 < 0) | |
2114 | abort (); | |
2115 | #endif | |
2116 | ||
2117 | val1 = PHI_ARG_DEF (phi, n1); | |
2118 | val2 = PHI_ARG_DEF (phi, n2); | |
2119 | ||
2120 | if (!operand_equal_p (val1, val2, 0)) | |
2121 | return false; | |
2122 | } | |
2123 | ||
2124 | return true; | |
2125 | } | |
2126 | ||
2127 | ||
2128 | /* Computing the Dominance Frontier: | |
2129 | ||
2130 | As described in Morgan, section 3.5, this may be done simply by | |
2131 | walking the dominator tree bottom-up, computing the frontier for | |
2132 | the children before the parent. When considering a block B, | |
2133 | there are two cases: | |
2134 | ||
2135 | (1) A flow graph edge leaving B that does not lead to a child | |
2136 | of B in the dominator tree must be a block that is either equal | |
2137 | to B or not dominated by B. Such blocks belong in the frontier | |
2138 | of B. | |
2139 | ||
2140 | (2) Consider a block X in the frontier of one of the children C | |
2141 | of B. If X is not equal to B and is not dominated by B, it | |
2142 | is in the frontier of B. */ | |
2143 | ||
2144 | static void | |
2145 | compute_dominance_frontiers_1 (bitmap *frontiers, basic_block bb, sbitmap done) | |
2146 | { | |
2147 | edge e; | |
2148 | basic_block c; | |
2149 | ||
2150 | SET_BIT (done, bb->index); | |
2151 | ||
2152 | /* Do the frontier of the children first. Not all children in the | |
2153 | dominator tree (blocks dominated by this one) are children in the | |
2154 | CFG, so check all blocks. */ | |
2155 | for (c = first_dom_son (CDI_DOMINATORS, bb); | |
2156 | c; | |
2157 | c = next_dom_son (CDI_DOMINATORS, c)) | |
2158 | { | |
2159 | if (! TEST_BIT (done, c->index)) | |
2160 | compute_dominance_frontiers_1 (frontiers, c, done); | |
2161 | } | |
2162 | ||
2163 | /* Find blocks conforming to rule (1) above. */ | |
2164 | for (e = bb->succ; e; e = e->succ_next) | |
2165 | { | |
2166 | if (e->dest == EXIT_BLOCK_PTR) | |
2167 | continue; | |
2168 | if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != bb) | |
2169 | bitmap_set_bit (frontiers[bb->index], e->dest->index); | |
2170 | } | |
2171 | ||
2172 | /* Find blocks conforming to rule (2). */ | |
2173 | for (c = first_dom_son (CDI_DOMINATORS, bb); | |
2174 | c; | |
2175 | c = next_dom_son (CDI_DOMINATORS, c)) | |
2176 | { | |
2177 | int x; | |
2178 | ||
2179 | EXECUTE_IF_SET_IN_BITMAP (frontiers[c->index], 0, x, | |
2180 | { | |
2181 | if (get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (x)) != bb) | |
2182 | bitmap_set_bit (frontiers[bb->index], x); | |
2183 | }); | |
2184 | } | |
2185 | } | |
2186 | ||
2187 | ||
2188 | void | |
2189 | compute_dominance_frontiers (bitmap *frontiers) | |
2190 | { | |
2191 | sbitmap done = sbitmap_alloc (last_basic_block); | |
2192 | ||
2193 | timevar_push (TV_DOM_FRONTIERS); | |
2194 | ||
2195 | sbitmap_zero (done); | |
2196 | ||
2197 | compute_dominance_frontiers_1 (frontiers, ENTRY_BLOCK_PTR->succ->dest, done); | |
2198 | ||
2199 | sbitmap_free (done); | |
2200 | ||
2201 | timevar_pop (TV_DOM_FRONTIERS); | |
2202 | } | |
2203 | ||
2204 | ||
2205 | ||
2206 | /*--------------------------------------------------------------------------- | |
2207 | Debugging functions | |
2208 | ---------------------------------------------------------------------------*/ | |
2209 | ||
2210 | /* Dump tree-specific information of block BB to file OUTF. */ | |
2211 | ||
2212 | void | |
2213 | tree_dump_bb (basic_block bb, FILE *outf, int indent) | |
2214 | { | |
2215 | dump_generic_bb (outf, bb, indent, TDF_VOPS); | |
2216 | } | |
2217 | ||
2218 | ||
2219 | /* Dump a basic block on stderr. */ | |
2220 | ||
2221 | void | |
2222 | debug_tree_bb (basic_block bb) | |
2223 | { | |
2224 | dump_bb (bb, stderr, 0); | |
2225 | } | |
2226 | ||
2227 | ||
2228 | /* Dump basic block with index N on stderr. */ | |
2229 | ||
2230 | basic_block | |
2231 | debug_tree_bb_n (int n) | |
2232 | { | |
2233 | debug_tree_bb (BASIC_BLOCK (n)); | |
2234 | return BASIC_BLOCK (n); | |
2235 | } | |
2236 | ||
2237 | ||
2238 | /* Dump the CFG on stderr. | |
2239 | ||
2240 | FLAGS are the same used by the tree dumping functions | |
2241 | (see TDF_* in tree.h). */ | |
2242 | ||
2243 | void | |
2244 | debug_tree_cfg (int flags) | |
2245 | { | |
2246 | dump_tree_cfg (stderr, flags); | |
2247 | } | |
2248 | ||
2249 | ||
2250 | /* Dump the program showing basic block boundaries on the given FILE. | |
2251 | ||
2252 | FLAGS are the same used by the tree dumping functions (see TDF_* in | |
2253 | tree.h). */ | |
2254 | ||
2255 | void | |
2256 | dump_tree_cfg (FILE *file, int flags) | |
2257 | { | |
2258 | if (flags & TDF_DETAILS) | |
2259 | { | |
2260 | const char *funcname | |
673fda6b | 2261 | = lang_hooks.decl_printable_name (current_function_decl, 2); |
6de9cd9a DN |
2262 | |
2263 | fputc ('\n', file); | |
2264 | fprintf (file, ";; Function %s\n\n", funcname); | |
2265 | fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n", | |
2266 | n_basic_blocks, n_edges, last_basic_block); | |
2267 | ||
2268 | brief_dump_cfg (file); | |
2269 | fprintf (file, "\n"); | |
2270 | } | |
2271 | ||
2272 | if (flags & TDF_STATS) | |
2273 | dump_cfg_stats (file); | |
2274 | ||
2275 | dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS); | |
2276 | } | |
2277 | ||
2278 | ||
2279 | /* Dump CFG statistics on FILE. */ | |
2280 | ||
2281 | void | |
2282 | dump_cfg_stats (FILE *file) | |
2283 | { | |
2284 | static long max_num_merged_labels = 0; | |
2285 | unsigned long size, total = 0; | |
2286 | long n_edges; | |
2287 | basic_block bb; | |
2288 | const char * const fmt_str = "%-30s%-13s%12s\n"; | |
2289 | const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n"; | |
2290 | const char * const fmt_str_3 = "%-43s%11lu%c\n"; | |
2291 | const char *funcname | |
673fda6b | 2292 | = lang_hooks.decl_printable_name (current_function_decl, 2); |
6de9cd9a DN |
2293 | |
2294 | ||
2295 | fprintf (file, "\nCFG Statistics for %s\n\n", funcname); | |
2296 | ||
2297 | fprintf (file, "---------------------------------------------------------\n"); | |
2298 | fprintf (file, fmt_str, "", " Number of ", "Memory"); | |
2299 | fprintf (file, fmt_str, "", " instances ", "used "); | |
2300 | fprintf (file, "---------------------------------------------------------\n"); | |
2301 | ||
2302 | size = n_basic_blocks * sizeof (struct basic_block_def); | |
2303 | total += size; | |
2304 | fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks, SCALE (size), | |
2305 | LABEL (size)); | |
2306 | ||
2307 | n_edges = 0; | |
2308 | FOR_EACH_BB (bb) | |
2309 | { | |
2310 | edge e; | |
2311 | for (e = bb->succ; e; e = e->succ_next) | |
2312 | n_edges++; | |
2313 | } | |
2314 | size = n_edges * sizeof (struct edge_def); | |
2315 | total += size; | |
2316 | fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size)); | |
2317 | ||
2318 | size = n_basic_blocks * sizeof (struct bb_ann_d); | |
2319 | total += size; | |
2320 | fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks, | |
2321 | SCALE (size), LABEL (size)); | |
2322 | ||
2323 | fprintf (file, "---------------------------------------------------------\n"); | |
2324 | fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total), | |
2325 | LABEL (total)); | |
2326 | fprintf (file, "---------------------------------------------------------\n"); | |
2327 | fprintf (file, "\n"); | |
2328 | ||
2329 | if (cfg_stats.num_merged_labels > max_num_merged_labels) | |
2330 | max_num_merged_labels = cfg_stats.num_merged_labels; | |
2331 | ||
2332 | fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n", | |
2333 | cfg_stats.num_merged_labels, max_num_merged_labels); | |
2334 | ||
2335 | fprintf (file, "\n"); | |
2336 | } | |
2337 | ||
2338 | ||
2339 | /* Dump CFG statistics on stderr. Keep extern so that it's always | |
2340 | linked in the final executable. */ | |
2341 | ||
2342 | void | |
2343 | debug_cfg_stats (void) | |
2344 | { | |
2345 | dump_cfg_stats (stderr); | |
2346 | } | |
2347 | ||
2348 | ||
2349 | /* Dump the flowgraph to a .vcg FILE. */ | |
2350 | ||
2351 | static void | |
2352 | tree_cfg2vcg (FILE *file) | |
2353 | { | |
2354 | edge e; | |
2355 | basic_block bb; | |
2356 | const char *funcname | |
673fda6b | 2357 | = lang_hooks.decl_printable_name (current_function_decl, 2); |
6de9cd9a DN |
2358 | |
2359 | /* Write the file header. */ | |
2360 | fprintf (file, "graph: { title: \"%s\"\n", funcname); | |
2361 | fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n"); | |
2362 | fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n"); | |
2363 | ||
2364 | /* Write blocks and edges. */ | |
2365 | for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) | |
2366 | { | |
2367 | fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"", | |
2368 | e->dest->index); | |
2369 | ||
2370 | if (e->flags & EDGE_FAKE) | |
2371 | fprintf (file, " linestyle: dotted priority: 10"); | |
2372 | else | |
2373 | fprintf (file, " linestyle: solid priority: 100"); | |
2374 | ||
2375 | fprintf (file, " }\n"); | |
2376 | } | |
2377 | fputc ('\n', file); | |
2378 | ||
2379 | FOR_EACH_BB (bb) | |
2380 | { | |
2381 | enum tree_code head_code, end_code; | |
2382 | const char *head_name, *end_name; | |
2383 | int head_line = 0; | |
2384 | int end_line = 0; | |
2385 | tree first = first_stmt (bb); | |
2386 | tree last = last_stmt (bb); | |
2387 | ||
2388 | if (first) | |
2389 | { | |
2390 | head_code = TREE_CODE (first); | |
2391 | head_name = tree_code_name[head_code]; | |
2392 | head_line = get_lineno (first); | |
2393 | } | |
2394 | else | |
2395 | head_name = "no-statement"; | |
2396 | ||
2397 | if (last) | |
2398 | { | |
2399 | end_code = TREE_CODE (last); | |
2400 | end_name = tree_code_name[end_code]; | |
2401 | end_line = get_lineno (last); | |
2402 | } | |
2403 | else | |
2404 | end_name = "no-statement"; | |
2405 | ||
2406 | fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n", | |
2407 | bb->index, bb->index, head_name, head_line, end_name, | |
2408 | end_line); | |
2409 | ||
2410 | for (e = bb->succ; e; e = e->succ_next) | |
2411 | { | |
2412 | if (e->dest == EXIT_BLOCK_PTR) | |
2413 | fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index); | |
2414 | else | |
2415 | fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index); | |
2416 | ||
2417 | if (e->flags & EDGE_FAKE) | |
2418 | fprintf (file, " priority: 10 linestyle: dotted"); | |
2419 | else | |
2420 | fprintf (file, " priority: 100 linestyle: solid"); | |
2421 | ||
2422 | fprintf (file, " }\n"); | |
2423 | } | |
2424 | ||
2425 | if (bb->next_bb != EXIT_BLOCK_PTR) | |
2426 | fputc ('\n', file); | |
2427 | } | |
2428 | ||
2429 | fputs ("}\n\n", file); | |
2430 | } | |
2431 | ||
2432 | ||
2433 | ||
2434 | /*--------------------------------------------------------------------------- | |
2435 | Miscellaneous helpers | |
2436 | ---------------------------------------------------------------------------*/ | |
2437 | ||
2438 | /* Return true if T represents a stmt that always transfers control. */ | |
2439 | ||
2440 | bool | |
2441 | is_ctrl_stmt (tree t) | |
2442 | { | |
2443 | return (TREE_CODE (t) == COND_EXPR | |
2444 | || TREE_CODE (t) == SWITCH_EXPR | |
2445 | || TREE_CODE (t) == GOTO_EXPR | |
2446 | || TREE_CODE (t) == RETURN_EXPR | |
2447 | || TREE_CODE (t) == RESX_EXPR); | |
2448 | } | |
2449 | ||
2450 | ||
2451 | /* Return true if T is a statement that may alter the flow of control | |
2452 | (e.g., a call to a non-returning function). */ | |
2453 | ||
2454 | bool | |
2455 | is_ctrl_altering_stmt (tree t) | |
2456 | { | |
2457 | tree call = t; | |
2458 | ||
2459 | #if defined ENABLE_CHECKING | |
2460 | if (t == NULL) | |
2461 | abort (); | |
2462 | #endif | |
2463 | ||
2464 | switch (TREE_CODE (t)) | |
2465 | { | |
2466 | case MODIFY_EXPR: | |
2467 | /* A MODIFY_EXPR with a rhs of a call has the characteristics | |
2468 | of the call. */ | |
2469 | call = TREE_OPERAND (t, 1); | |
2470 | if (TREE_CODE (call) != CALL_EXPR) | |
2471 | break; | |
2472 | /* FALLTHRU */ | |
2473 | ||
2474 | case CALL_EXPR: | |
2475 | /* A non-pure/const CALL_EXPR alters flow control if the current | |
2476 | function has nonlocal labels. */ | |
2477 | if (TREE_SIDE_EFFECTS (t) | |
2478 | && current_function_has_nonlocal_label) | |
2479 | return true; | |
2480 | ||
2481 | /* A CALL_EXPR also alters control flow if it does not return. */ | |
2482 | if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP)) | |
2483 | return true; | |
2484 | break; | |
2485 | ||
2486 | default: | |
2487 | return false; | |
2488 | } | |
2489 | ||
2490 | /* If a statement can throw, it alters control flow. */ | |
2491 | return tree_can_throw_internal (t); | |
2492 | } | |
2493 | ||
2494 | ||
2495 | /* Return true if T is a computed goto. */ | |
2496 | ||
2497 | bool | |
2498 | computed_goto_p (tree t) | |
2499 | { | |
2500 | return (TREE_CODE (t) == GOTO_EXPR | |
2501 | && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL); | |
2502 | } | |
2503 | ||
2504 | ||
2505 | /* Checks whether EXPR is a simple local goto. */ | |
2506 | ||
2507 | bool | |
2508 | simple_goto_p (tree expr) | |
2509 | { | |
2510 | return (TREE_CODE (expr) == GOTO_EXPR | |
2511 | && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL | |
2512 | && (decl_function_context (GOTO_DESTINATION (expr)) | |
2513 | == current_function_decl)); | |
2514 | } | |
2515 | ||
2516 | ||
2517 | /* Return true if T should start a new basic block. PREV_T is the | |
2518 | statement preceding T. It is used when T is a label or a case label. | |
2519 | Labels should only start a new basic block if their previous statement | |
2520 | wasn't a label. Otherwise, sequence of labels would generate | |
2521 | unnecessary basic blocks that only contain a single label. */ | |
2522 | ||
2523 | static inline bool | |
2524 | stmt_starts_bb_p (tree t, tree prev_t) | |
2525 | { | |
2526 | enum tree_code code; | |
2527 | ||
2528 | if (t == NULL_TREE) | |
2529 | return false; | |
2530 | ||
2531 | /* LABEL_EXPRs start a new basic block only if the preceding | |
2532 | statement wasn't a label of the same type. This prevents the | |
2533 | creation of consecutive blocks that have nothing but a single | |
2534 | label. */ | |
2535 | code = TREE_CODE (t); | |
2536 | if (code == LABEL_EXPR) | |
2537 | { | |
2538 | /* Nonlocal and computed GOTO targets always start a new block. */ | |
2539 | if (code == LABEL_EXPR | |
2540 | && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t)) | |
2541 | || FORCED_LABEL (LABEL_EXPR_LABEL (t)))) | |
2542 | return true; | |
2543 | ||
2544 | if (prev_t && TREE_CODE (prev_t) == code) | |
2545 | { | |
2546 | if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t))) | |
2547 | return true; | |
2548 | ||
2549 | cfg_stats.num_merged_labels++; | |
2550 | return false; | |
2551 | } | |
2552 | else | |
2553 | return true; | |
2554 | } | |
2555 | ||
2556 | return false; | |
2557 | } | |
2558 | ||
2559 | ||
2560 | /* Return true if T should end a basic block. */ | |
2561 | ||
2562 | bool | |
2563 | stmt_ends_bb_p (tree t) | |
2564 | { | |
2565 | return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t); | |
2566 | } | |
2567 | ||
2568 | ||
2569 | /* Add gotos that used to be represented implicitly in the CFG. */ | |
2570 | ||
2571 | void | |
2572 | disband_implicit_edges (void) | |
2573 | { | |
2574 | basic_block bb; | |
2575 | block_stmt_iterator last; | |
2576 | edge e; | |
eb4e1c01 | 2577 | tree stmt, label; |
6de9cd9a DN |
2578 | |
2579 | FOR_EACH_BB (bb) | |
2580 | { | |
2581 | last = bsi_last (bb); | |
2582 | stmt = last_stmt (bb); | |
2583 | ||
2584 | if (stmt && TREE_CODE (stmt) == COND_EXPR) | |
2585 | { | |
2586 | /* Remove superfluous gotos from COND_EXPR branches. Moved | |
2587 | from cfg_remove_useless_stmts here since it violates the | |
2588 | invariants for tree--cfg correspondence and thus fits better | |
2589 | here where we do it anyway. */ | |
2590 | for (e = bb->succ; e; e = e->succ_next) | |
2591 | { | |
2592 | if (e->dest != bb->next_bb) | |
2593 | continue; | |
2594 | ||
2595 | if (e->flags & EDGE_TRUE_VALUE) | |
2596 | COND_EXPR_THEN (stmt) = build_empty_stmt (); | |
2597 | else if (e->flags & EDGE_FALSE_VALUE) | |
2598 | COND_EXPR_ELSE (stmt) = build_empty_stmt (); | |
2599 | else | |
2600 | abort (); | |
2601 | e->flags |= EDGE_FALLTHRU; | |
2602 | } | |
2603 | ||
2604 | continue; | |
2605 | } | |
2606 | ||
2607 | if (stmt && TREE_CODE (stmt) == RETURN_EXPR) | |
2608 | { | |
2609 | /* Remove the RETURN_EXPR if we may fall though to the exit | |
2610 | instead. */ | |
2611 | if (!bb->succ | |
2612 | || bb->succ->succ_next | |
2613 | || bb->succ->dest != EXIT_BLOCK_PTR) | |
2614 | abort (); | |
2615 | ||
2616 | if (bb->next_bb == EXIT_BLOCK_PTR | |
2617 | && !TREE_OPERAND (stmt, 0)) | |
2618 | { | |
2619 | bsi_remove (&last); | |
2620 | bb->succ->flags |= EDGE_FALLTHRU; | |
2621 | } | |
2622 | continue; | |
2623 | } | |
2624 | ||
2625 | /* There can be no fallthru edge if the last statement is a control | |
2626 | one. */ | |
2627 | if (stmt && is_ctrl_stmt (stmt)) | |
2628 | continue; | |
2629 | ||
2630 | /* Find a fallthru edge and emit the goto if necessary. */ | |
2631 | for (e = bb->succ; e; e = e->succ_next) | |
2632 | if (e->flags & EDGE_FALLTHRU) | |
2633 | break; | |
2634 | ||
62b857ea | 2635 | if (!e || e->dest == bb->next_bb) |
6de9cd9a DN |
2636 | continue; |
2637 | ||
2638 | if (e->dest == EXIT_BLOCK_PTR) | |
2639 | abort (); | |
2640 | ||
2641 | label = tree_block_label (e->dest); | |
2642 | ||
62b857ea RH |
2643 | stmt = build1 (GOTO_EXPR, void_type_node, label); |
2644 | SET_EXPR_LOCUS (stmt, e->goto_locus); | |
2645 | bsi_insert_after (&last, stmt, BSI_NEW_STMT); | |
6de9cd9a DN |
2646 | e->flags &= ~EDGE_FALLTHRU; |
2647 | } | |
2648 | } | |
2649 | ||
242229bb | 2650 | /* Remove block annotations and other datastructures. */ |
6de9cd9a DN |
2651 | |
2652 | void | |
242229bb | 2653 | delete_tree_cfg_annotations (void) |
6de9cd9a | 2654 | { |
242229bb | 2655 | basic_block bb; |
6de9cd9a DN |
2656 | if (n_basic_blocks > 0) |
2657 | free_blocks_annotations (); | |
2658 | ||
6de9cd9a DN |
2659 | label_to_block_map = NULL; |
2660 | free_rbi_pool (); | |
242229bb JH |
2661 | FOR_EACH_BB (bb) |
2662 | bb->rbi = NULL; | |
6de9cd9a DN |
2663 | } |
2664 | ||
2665 | ||
2666 | /* Return the first statement in basic block BB. */ | |
2667 | ||
2668 | tree | |
2669 | first_stmt (basic_block bb) | |
2670 | { | |
2671 | block_stmt_iterator i = bsi_start (bb); | |
2672 | return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE; | |
2673 | } | |
2674 | ||
2675 | ||
2676 | /* Return the last statement in basic block BB. */ | |
2677 | ||
2678 | tree | |
2679 | last_stmt (basic_block bb) | |
2680 | { | |
2681 | block_stmt_iterator b = bsi_last (bb); | |
2682 | return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE; | |
2683 | } | |
2684 | ||
2685 | ||
2686 | /* Return a pointer to the last statement in block BB. */ | |
2687 | ||
2688 | tree * | |
2689 | last_stmt_ptr (basic_block bb) | |
2690 | { | |
2691 | block_stmt_iterator last = bsi_last (bb); | |
2692 | return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL; | |
2693 | } | |
2694 | ||
2695 | ||
2696 | /* Return the last statement of an otherwise empty block. Return NULL | |
2697 | if the block is totally empty, or if it contains more than one | |
2698 | statement. */ | |
2699 | ||
2700 | tree | |
2701 | last_and_only_stmt (basic_block bb) | |
2702 | { | |
2703 | block_stmt_iterator i = bsi_last (bb); | |
2704 | tree last, prev; | |
2705 | ||
2706 | if (bsi_end_p (i)) | |
2707 | return NULL_TREE; | |
2708 | ||
2709 | last = bsi_stmt (i); | |
2710 | bsi_prev (&i); | |
2711 | if (bsi_end_p (i)) | |
2712 | return last; | |
2713 | ||
2714 | /* Empty statements should no longer appear in the instruction stream. | |
2715 | Everything that might have appeared before should be deleted by | |
2716 | remove_useless_stmts, and the optimizers should just bsi_remove | |
2717 | instead of smashing with build_empty_stmt. | |
2718 | ||
2719 | Thus the only thing that should appear here in a block containing | |
2720 | one executable statement is a label. */ | |
2721 | prev = bsi_stmt (i); | |
2722 | if (TREE_CODE (prev) == LABEL_EXPR) | |
2723 | return last; | |
2724 | else | |
2725 | return NULL_TREE; | |
2726 | } | |
2727 | ||
2728 | ||
2729 | /* Mark BB as the basic block holding statement T. */ | |
2730 | ||
2731 | void | |
2732 | set_bb_for_stmt (tree t, basic_block bb) | |
2733 | { | |
2734 | if (TREE_CODE (t) == STATEMENT_LIST) | |
2735 | { | |
2736 | tree_stmt_iterator i; | |
2737 | for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) | |
2738 | set_bb_for_stmt (tsi_stmt (i), bb); | |
2739 | } | |
2740 | else | |
2741 | { | |
2742 | stmt_ann_t ann = get_stmt_ann (t); | |
2743 | ann->bb = bb; | |
2744 | ||
2745 | /* If the statement is a label, add the label to block-to-labels map | |
2746 | so that we can speed up edge creation for GOTO_EXPRs. */ | |
2747 | if (TREE_CODE (t) == LABEL_EXPR) | |
2748 | { | |
2749 | int uid; | |
2750 | ||
2751 | t = LABEL_EXPR_LABEL (t); | |
2752 | uid = LABEL_DECL_UID (t); | |
2753 | if (uid == -1) | |
2754 | { | |
2755 | LABEL_DECL_UID (t) = uid = cfun->last_label_uid++; | |
2756 | if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid) | |
2757 | VARRAY_GROW (label_to_block_map, 3 * uid / 2); | |
2758 | } | |
2759 | else | |
2760 | { | |
2761 | #ifdef ENABLE_CHECKING | |
2762 | /* We're moving an existing label. Make sure that we've | |
2763 | removed it from the old block. */ | |
2764 | if (bb && VARRAY_BB (label_to_block_map, uid)) | |
2765 | abort (); | |
2766 | #endif | |
2767 | } | |
2768 | VARRAY_BB (label_to_block_map, uid) = bb; | |
2769 | } | |
2770 | } | |
2771 | } | |
2772 | ||
2773 | ||
2774 | /* Insert statement (or statement list) T before the statement | |
2775 | pointed-to by iterator I. M specifies how to update iterator I | |
2776 | after insertion (see enum bsi_iterator_update). */ | |
2777 | ||
2778 | void | |
2779 | bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) | |
2780 | { | |
2781 | set_bb_for_stmt (t, i->bb); | |
2782 | modify_stmt (t); | |
2783 | tsi_link_before (&i->tsi, t, m); | |
2784 | } | |
2785 | ||
2786 | ||
2787 | /* Insert statement (or statement list) T after the statement | |
2788 | pointed-to by iterator I. M specifies how to update iterator I | |
2789 | after insertion (see enum bsi_iterator_update). */ | |
2790 | ||
2791 | void | |
2792 | bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) | |
2793 | { | |
2794 | set_bb_for_stmt (t, i->bb); | |
2795 | modify_stmt (t); | |
2796 | tsi_link_after (&i->tsi, t, m); | |
2797 | } | |
2798 | ||
2799 | ||
2800 | /* Remove the statement pointed to by iterator I. The iterator is updated | |
2801 | to the next statement. */ | |
2802 | ||
2803 | void | |
2804 | bsi_remove (block_stmt_iterator *i) | |
2805 | { | |
2806 | tree t = bsi_stmt (*i); | |
2807 | set_bb_for_stmt (t, NULL); | |
2808 | modify_stmt (t); | |
2809 | tsi_delink (&i->tsi); | |
2810 | } | |
2811 | ||
2812 | ||
2813 | /* Move the statement at FROM so it comes right after the statement at TO. */ | |
2814 | ||
2815 | void | |
2816 | bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to) | |
2817 | { | |
2818 | tree stmt = bsi_stmt (*from); | |
2819 | bsi_remove (from); | |
2820 | bsi_insert_after (to, stmt, BSI_SAME_STMT); | |
2821 | } | |
2822 | ||
2823 | ||
2824 | /* Move the statement at FROM so it comes right before the statement at TO. */ | |
2825 | ||
2826 | void | |
2827 | bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to) | |
2828 | { | |
2829 | tree stmt = bsi_stmt (*from); | |
2830 | bsi_remove (from); | |
2831 | bsi_insert_before (to, stmt, BSI_SAME_STMT); | |
2832 | } | |
2833 | ||
2834 | ||
2835 | /* Move the statement at FROM to the end of basic block BB. */ | |
2836 | ||
2837 | void | |
2838 | bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb) | |
2839 | { | |
2840 | block_stmt_iterator last = bsi_last (bb); | |
2841 | ||
2842 | /* Have to check bsi_end_p because it could be an empty block. */ | |
2843 | if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last))) | |
2844 | bsi_move_before (from, &last); | |
2845 | else | |
2846 | bsi_move_after (from, &last); | |
2847 | } | |
2848 | ||
2849 | ||
2850 | /* Replace the contents of the statement pointed to by iterator BSI | |
2851 | with STMT. If PRESERVE_EH_INFO is true, the exception handling | |
2852 | information of the original statement is preserved. */ | |
2853 | ||
2854 | void | |
2855 | bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info) | |
2856 | { | |
2857 | int eh_region; | |
2858 | tree orig_stmt = bsi_stmt (*bsi); | |
2859 | ||
2860 | SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt)); | |
2861 | set_bb_for_stmt (stmt, bsi->bb); | |
2862 | ||
2863 | /* Preserve EH region information from the original statement, if | |
2864 | requested by the caller. */ | |
2865 | if (preserve_eh_info) | |
2866 | { | |
2867 | eh_region = lookup_stmt_eh_region (orig_stmt); | |
2868 | if (eh_region >= 0) | |
2869 | add_stmt_to_eh_region (stmt, eh_region); | |
2870 | } | |
2871 | ||
2872 | *bsi_stmt_ptr (*bsi) = stmt; | |
2873 | modify_stmt (stmt); | |
2874 | } | |
2875 | ||
2876 | ||
2877 | /* Insert the statement pointed-to by BSI into edge E. Every attempt | |
2878 | is made to place the statement in an existing basic block, but | |
2879 | sometimes that isn't possible. When it isn't possible, the edge is | |
2880 | split and the statement is added to the new block. | |
2881 | ||
2882 | In all cases, the returned *BSI points to the correct location. The | |
2883 | return value is true if insertion should be done after the location, | |
2884 | or false if it should be done before the location. */ | |
2885 | ||
2886 | static bool | |
2887 | tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi) | |
2888 | { | |
2889 | basic_block dest, src; | |
2890 | tree tmp; | |
2891 | ||
2892 | dest = e->dest; | |
2893 | restart: | |
2894 | ||
2895 | /* If the destination has one predecessor which has no PHI nodes, | |
2896 | insert there. Except for the exit block. | |
2897 | ||
2898 | The requirement for no PHI nodes could be relaxed. Basically we | |
2899 | would have to examine the PHIs to prove that none of them used | |
2900 | the value set by the statement we want to insert on E. That | |
2901 | hardly seems worth the effort. */ | |
2902 | if (dest->pred->pred_next == NULL | |
2903 | && ! phi_nodes (dest) | |
2904 | && dest != EXIT_BLOCK_PTR) | |
2905 | { | |
2906 | *bsi = bsi_start (dest); | |
2907 | if (bsi_end_p (*bsi)) | |
2908 | return true; | |
2909 | ||
2910 | /* Make sure we insert after any leading labels. */ | |
2911 | tmp = bsi_stmt (*bsi); | |
2912 | while (TREE_CODE (tmp) == LABEL_EXPR) | |
2913 | { | |
2914 | bsi_next (bsi); | |
2915 | if (bsi_end_p (*bsi)) | |
2916 | break; | |
2917 | tmp = bsi_stmt (*bsi); | |
2918 | } | |
2919 | ||
2920 | if (bsi_end_p (*bsi)) | |
2921 | { | |
2922 | *bsi = bsi_last (dest); | |
2923 | return true; | |
2924 | } | |
2925 | else | |
2926 | return false; | |
2927 | } | |
2928 | ||
2929 | /* If the source has one successor, the edge is not abnormal and | |
2930 | the last statement does not end a basic block, insert there. | |
2931 | Except for the entry block. */ | |
2932 | src = e->src; | |
2933 | if ((e->flags & EDGE_ABNORMAL) == 0 | |
2934 | && src->succ->succ_next == NULL | |
2935 | && src != ENTRY_BLOCK_PTR) | |
2936 | { | |
2937 | *bsi = bsi_last (src); | |
2938 | if (bsi_end_p (*bsi)) | |
2939 | return true; | |
2940 | ||
2941 | tmp = bsi_stmt (*bsi); | |
2942 | if (!stmt_ends_bb_p (tmp)) | |
2943 | return true; | |
ce068299 JH |
2944 | |
2945 | /* Insert code just before returning the value. We may need to decompose | |
2946 | the return in the case it contains non-trivial operand. */ | |
2947 | if (TREE_CODE (tmp) == RETURN_EXPR) | |
2948 | { | |
2949 | tree op = TREE_OPERAND (tmp, 0); | |
2950 | if (!is_gimple_val (op)) | |
2951 | { | |
2952 | if (TREE_CODE (op) != MODIFY_EXPR) | |
2953 | abort (); | |
2954 | bsi_insert_before (bsi, op, BSI_NEW_STMT); | |
2955 | TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0); | |
2956 | } | |
2957 | bsi_prev (bsi); | |
2958 | return true; | |
2959 | } | |
6de9cd9a DN |
2960 | } |
2961 | ||
2962 | /* Otherwise, create a new basic block, and split this edge. */ | |
2963 | dest = split_edge (e); | |
2964 | e = dest->pred; | |
2965 | goto restart; | |
2966 | } | |
2967 | ||
2968 | ||
2969 | /* This routine will commit all pending edge insertions, creating any new | |
2970 | basic blocks which are necessary. | |
2971 | ||
2972 | If specified, NEW_BLOCKS returns a count of the number of new basic | |
2973 | blocks which were created. */ | |
2974 | ||
2975 | void | |
2976 | bsi_commit_edge_inserts (int *new_blocks) | |
2977 | { | |
2978 | basic_block bb; | |
2979 | edge e; | |
2980 | int blocks; | |
2981 | ||
2982 | blocks = n_basic_blocks; | |
2983 | ||
2984 | bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ); | |
2985 | ||
2986 | FOR_EACH_BB (bb) | |
2987 | for (e = bb->succ; e; e = e->succ_next) | |
2988 | bsi_commit_edge_inserts_1 (e); | |
2989 | ||
2990 | if (new_blocks) | |
2991 | *new_blocks = n_basic_blocks - blocks; | |
2992 | } | |
2993 | ||
2994 | ||
2995 | /* Commit insertions pending at edge E. */ | |
2996 | ||
2997 | static void | |
2998 | bsi_commit_edge_inserts_1 (edge e) | |
2999 | { | |
3000 | if (PENDING_STMT (e)) | |
3001 | { | |
3002 | block_stmt_iterator bsi; | |
3003 | tree stmt = PENDING_STMT (e); | |
3004 | ||
3005 | PENDING_STMT (e) = NULL_TREE; | |
3006 | ||
3007 | if (tree_find_edge_insert_loc (e, &bsi)) | |
3008 | bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); | |
3009 | else | |
3010 | bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); | |
3011 | } | |
3012 | } | |
3013 | ||
3014 | ||
3015 | /* Add STMT to the pending list of edge E. No actual insertion is | |
3016 | made until a call to bsi_commit_edge_inserts () is made. */ | |
3017 | ||
3018 | void | |
3019 | bsi_insert_on_edge (edge e, tree stmt) | |
3020 | { | |
3021 | append_to_statement_list (stmt, &PENDING_STMT (e)); | |
3022 | } | |
3023 | ||
3024 | ||
3025 | /* Specialized edge insertion for SSA-PRE. FIXME: This should | |
3026 | probably disappear. The only reason it's here is because PRE needs | |
3027 | the call to tree_find_edge_insert_loc(). */ | |
3028 | ||
3029 | void pre_insert_on_edge (edge e, tree stmt); | |
3030 | ||
3031 | void | |
3032 | pre_insert_on_edge (edge e, tree stmt) | |
3033 | { | |
3034 | block_stmt_iterator bsi; | |
3035 | ||
3036 | if (PENDING_STMT (e)) | |
3037 | abort (); | |
3038 | ||
3039 | if (tree_find_edge_insert_loc (e, &bsi)) | |
3040 | bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); | |
3041 | else | |
3042 | bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); | |
3043 | } | |
3044 | ||
3045 | ||
3046 | /*--------------------------------------------------------------------------- | |
3047 | Tree specific functions for CFG manipulation | |
3048 | ---------------------------------------------------------------------------*/ | |
3049 | ||
3050 | /* Split a (typically critical) edge EDGE_IN. Return the new block. | |
3051 | Abort on abnormal edges. */ | |
3052 | ||
3053 | static basic_block | |
3054 | tree_split_edge (edge edge_in) | |
3055 | { | |
3056 | basic_block new_bb, after_bb, dest, src; | |
3057 | edge new_edge, e; | |
3058 | tree phi; | |
3059 | int i, num_elem; | |
3060 | ||
3061 | /* Abnormal edges cannot be split. */ | |
3062 | if (edge_in->flags & EDGE_ABNORMAL) | |
3063 | abort (); | |
3064 | ||
3065 | src = edge_in->src; | |
3066 | dest = edge_in->dest; | |
3067 | ||
3068 | /* Place the new block in the block list. Try to keep the new block | |
3069 | near its "logical" location. This is of most help to humans looking | |
3070 | at debugging dumps. */ | |
3071 | for (e = dest->pred; e; e = e->pred_next) | |
3072 | if (e->src->next_bb == dest) | |
3073 | break; | |
3074 | if (!e) | |
3075 | after_bb = dest->prev_bb; | |
3076 | else | |
3077 | after_bb = edge_in->src; | |
3078 | ||
3079 | new_bb = create_empty_bb (after_bb); | |
3080 | new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU); | |
3081 | ||
3082 | /* Find all the PHI arguments on the original edge, and change them to | |
3083 | the new edge. Do it before redirection, so that the argument does not | |
3084 | get removed. */ | |
17192884 | 3085 | for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3086 | { |
3087 | num_elem = PHI_NUM_ARGS (phi); | |
3088 | for (i = 0; i < num_elem; i++) | |
3089 | if (PHI_ARG_EDGE (phi, i) == edge_in) | |
3090 | { | |
3091 | PHI_ARG_EDGE (phi, i) = new_edge; | |
3092 | break; | |
3093 | } | |
3094 | } | |
3095 | ||
3096 | if (!redirect_edge_and_branch (edge_in, new_bb)) | |
3097 | abort (); | |
3098 | ||
3099 | if (PENDING_STMT (edge_in)) | |
3100 | abort (); | |
3101 | ||
3102 | return new_bb; | |
3103 | } | |
3104 | ||
3105 | ||
3106 | /* Return true when BB has label LABEL in it. */ | |
3107 | ||
3108 | static bool | |
3109 | has_label_p (basic_block bb, tree label) | |
3110 | { | |
3111 | block_stmt_iterator bsi; | |
3112 | ||
3113 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3114 | { | |
3115 | tree stmt = bsi_stmt (bsi); | |
3116 | ||
3117 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
3118 | return false; | |
3119 | if (LABEL_EXPR_LABEL (stmt) == label) | |
3120 | return true; | |
3121 | } | |
3122 | return false; | |
3123 | } | |
3124 | ||
3125 | ||
3126 | /* Callback for walk_tree, check that all elements with address taken are | |
3127 | properly noticed as such. */ | |
3128 | ||
3129 | static tree | |
3130 | verify_expr (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, | |
3131 | void *data ATTRIBUTE_UNUSED) | |
3132 | { | |
3133 | tree t = *tp, x; | |
3134 | ||
3135 | if (TYPE_P (t)) | |
3136 | *walk_subtrees = 0; | |
3137 | ||
3138 | switch (TREE_CODE (t)) | |
3139 | { | |
3140 | case SSA_NAME: | |
3141 | if (SSA_NAME_IN_FREE_LIST (t)) | |
3142 | { | |
3143 | error ("SSA name in freelist but still referenced"); | |
3144 | return *tp; | |
3145 | } | |
3146 | break; | |
3147 | ||
3148 | case MODIFY_EXPR: | |
3149 | x = TREE_OPERAND (t, 0); | |
3150 | if (TREE_CODE (x) == BIT_FIELD_REF | |
3151 | && is_gimple_reg (TREE_OPERAND (x, 0))) | |
3152 | { | |
3153 | error ("GIMPLE register modified with BIT_FIELD_REF"); | |
3154 | return *tp; | |
3155 | } | |
3156 | break; | |
3157 | ||
3158 | case ADDR_EXPR: | |
3159 | x = TREE_OPERAND (t, 0); | |
3160 | while (TREE_CODE (x) == ARRAY_REF | |
3161 | || TREE_CODE (x) == COMPONENT_REF | |
3162 | || TREE_CODE (x) == REALPART_EXPR | |
3163 | || TREE_CODE (x) == IMAGPART_EXPR) | |
3164 | x = TREE_OPERAND (x, 0); | |
3165 | if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL) | |
3166 | return NULL; | |
3167 | if (!TREE_ADDRESSABLE (x)) | |
3168 | { | |
3169 | error ("address taken, but ADDRESSABLE bit not set"); | |
3170 | return x; | |
3171 | } | |
3172 | break; | |
3173 | ||
3174 | case COND_EXPR: | |
3175 | x = TREE_OPERAND (t, 0); | |
3176 | if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE) | |
3177 | { | |
3178 | error ("non-boolean used in condition"); | |
3179 | return x; | |
3180 | } | |
3181 | break; | |
3182 | ||
3183 | case NOP_EXPR: | |
3184 | case CONVERT_EXPR: | |
3185 | case FIX_TRUNC_EXPR: | |
3186 | case FIX_CEIL_EXPR: | |
3187 | case FIX_FLOOR_EXPR: | |
3188 | case FIX_ROUND_EXPR: | |
3189 | case FLOAT_EXPR: | |
3190 | case NEGATE_EXPR: | |
3191 | case ABS_EXPR: | |
3192 | case BIT_NOT_EXPR: | |
3193 | case NON_LVALUE_EXPR: | |
3194 | case TRUTH_NOT_EXPR: | |
3195 | x = TREE_OPERAND (t, 0); | |
3196 | /* We check for constants explicitly since they are not considered | |
3197 | gimple invariants if they overflowed. */ | |
3198 | if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c' | |
3199 | && !is_gimple_val (x)) | |
3200 | { | |
3201 | error ("Invalid operand to unary operator"); | |
3202 | return x; | |
3203 | } | |
3204 | break; | |
3205 | ||
3206 | case REALPART_EXPR: | |
3207 | case IMAGPART_EXPR: | |
3208 | break; | |
3209 | ||
3210 | case LT_EXPR: | |
3211 | case LE_EXPR: | |
3212 | case GT_EXPR: | |
3213 | case GE_EXPR: | |
3214 | case EQ_EXPR: | |
3215 | case NE_EXPR: | |
3216 | case UNORDERED_EXPR: | |
3217 | case ORDERED_EXPR: | |
3218 | case UNLT_EXPR: | |
3219 | case UNLE_EXPR: | |
3220 | case UNGT_EXPR: | |
3221 | case UNGE_EXPR: | |
3222 | case UNEQ_EXPR: | |
d1a7edaf | 3223 | case LTGT_EXPR: |
6de9cd9a DN |
3224 | case PLUS_EXPR: |
3225 | case MINUS_EXPR: | |
3226 | case MULT_EXPR: | |
3227 | case TRUNC_DIV_EXPR: | |
3228 | case CEIL_DIV_EXPR: | |
3229 | case FLOOR_DIV_EXPR: | |
3230 | case ROUND_DIV_EXPR: | |
3231 | case TRUNC_MOD_EXPR: | |
3232 | case CEIL_MOD_EXPR: | |
3233 | case FLOOR_MOD_EXPR: | |
3234 | case ROUND_MOD_EXPR: | |
3235 | case RDIV_EXPR: | |
3236 | case EXACT_DIV_EXPR: | |
3237 | case MIN_EXPR: | |
3238 | case MAX_EXPR: | |
3239 | case LSHIFT_EXPR: | |
3240 | case RSHIFT_EXPR: | |
3241 | case LROTATE_EXPR: | |
3242 | case RROTATE_EXPR: | |
3243 | case BIT_IOR_EXPR: | |
3244 | case BIT_XOR_EXPR: | |
3245 | case BIT_AND_EXPR: | |
3246 | x = TREE_OPERAND (t, 0); | |
3247 | /* We check for constants explicitly since they are not considered | |
3248 | gimple invariants if they overflowed. */ | |
3249 | if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c' | |
3250 | && !is_gimple_val (x)) | |
3251 | { | |
3252 | error ("Invalid operand to binary operator"); | |
3253 | return x; | |
3254 | } | |
3255 | x = TREE_OPERAND (t, 1); | |
3256 | /* We check for constants explicitly since they are not considered | |
3257 | gimple invariants if they overflowed. */ | |
3258 | if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c' | |
3259 | && !is_gimple_val (x)) | |
3260 | { | |
3261 | error ("Invalid operand to binary operator"); | |
3262 | return x; | |
3263 | } | |
3264 | break; | |
3265 | ||
3266 | default: | |
3267 | break; | |
3268 | } | |
3269 | return NULL; | |
3270 | } | |
3271 | ||
3272 | ||
3273 | /* Verify STMT, return true if STMT is not in GIMPLE form. | |
3274 | TODO: Implement type checking. */ | |
3275 | ||
3276 | static bool | |
3277 | verify_stmt (tree stmt) | |
3278 | { | |
3279 | tree addr; | |
3280 | ||
3281 | if (!is_gimple_stmt (stmt)) | |
3282 | { | |
3283 | error ("Is not a valid GIMPLE statement."); | |
3284 | debug_generic_stmt (stmt); | |
3285 | return true; | |
3286 | } | |
3287 | ||
3288 | addr = walk_tree (&stmt, verify_expr, NULL, NULL); | |
3289 | if (addr) | |
3290 | { | |
3291 | debug_generic_stmt (addr); | |
3292 | return true; | |
3293 | } | |
3294 | ||
3295 | return false; | |
3296 | } | |
3297 | ||
3298 | ||
3299 | /* Return true when the T can be shared. */ | |
3300 | ||
3301 | static bool | |
3302 | tree_node_can_be_shared (tree t) | |
3303 | { | |
3304 | if (TYPE_P (t) || DECL_P (t) | |
3305 | /* We check for constants explicitly since they are not considered | |
3306 | gimple invariants if they overflowed. */ | |
3307 | || TREE_CODE_CLASS (TREE_CODE (t)) == 'c' | |
3308 | || is_gimple_min_invariant (t) | |
3309 | || TREE_CODE (t) == SSA_NAME) | |
3310 | return true; | |
3311 | ||
3312 | while ((TREE_CODE (t) == ARRAY_REF | |
3313 | /* We check for constants explicitly since they are not considered | |
3314 | gimple invariants if they overflowed. */ | |
3315 | && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, 1))) == 'c' | |
3316 | || is_gimple_min_invariant (TREE_OPERAND (t, 1)))) | |
3317 | || (TREE_CODE (t) == COMPONENT_REF | |
3318 | || TREE_CODE (t) == REALPART_EXPR | |
3319 | || TREE_CODE (t) == IMAGPART_EXPR)) | |
3320 | t = TREE_OPERAND (t, 0); | |
3321 | ||
3322 | if (DECL_P (t)) | |
3323 | return true; | |
3324 | ||
3325 | return false; | |
3326 | } | |
3327 | ||
3328 | ||
3329 | /* Called via walk_trees. Verify tree sharing. */ | |
3330 | ||
3331 | static tree | |
3332 | verify_node_sharing (tree * tp, int *walk_subtrees, void *data) | |
3333 | { | |
3334 | htab_t htab = (htab_t) data; | |
3335 | void **slot; | |
3336 | ||
3337 | if (tree_node_can_be_shared (*tp)) | |
3338 | { | |
3339 | *walk_subtrees = false; | |
3340 | return NULL; | |
3341 | } | |
3342 | ||
3343 | slot = htab_find_slot (htab, *tp, INSERT); | |
3344 | if (*slot) | |
3345 | return *slot; | |
3346 | *slot = *tp; | |
3347 | ||
3348 | return NULL; | |
3349 | } | |
3350 | ||
3351 | ||
3352 | /* Verify the GIMPLE statement chain. */ | |
3353 | ||
3354 | void | |
3355 | verify_stmts (void) | |
3356 | { | |
3357 | basic_block bb; | |
3358 | block_stmt_iterator bsi; | |
3359 | bool err = false; | |
3360 | htab_t htab; | |
3361 | tree addr; | |
3362 | ||
3363 | timevar_push (TV_TREE_STMT_VERIFY); | |
3364 | htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL); | |
3365 | ||
3366 | FOR_EACH_BB (bb) | |
3367 | { | |
3368 | tree phi; | |
3369 | int i; | |
3370 | ||
17192884 | 3371 | for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3372 | { |
3373 | int phi_num_args = PHI_NUM_ARGS (phi); | |
3374 | ||
3375 | for (i = 0; i < phi_num_args; i++) | |
3376 | { | |
3377 | tree t = PHI_ARG_DEF (phi, i); | |
3378 | tree addr; | |
3379 | ||
3380 | /* Addressable variables do have SSA_NAMEs but they | |
3381 | are not considered gimple values. */ | |
3382 | if (TREE_CODE (t) != SSA_NAME | |
3383 | && TREE_CODE (t) != FUNCTION_DECL | |
3384 | && !is_gimple_val (t)) | |
3385 | { | |
3386 | error ("PHI def is not a GIMPLE value"); | |
3387 | debug_generic_stmt (phi); | |
3388 | debug_generic_stmt (t); | |
3389 | err |= true; | |
3390 | } | |
3391 | ||
3392 | addr = walk_tree (&t, verify_expr, NULL, NULL); | |
3393 | if (addr) | |
3394 | { | |
3395 | debug_generic_stmt (addr); | |
3396 | err |= true; | |
3397 | } | |
3398 | ||
3399 | addr = walk_tree (&t, verify_node_sharing, htab, NULL); | |
3400 | if (addr) | |
3401 | { | |
3402 | error ("Incorrect sharing of tree nodes"); | |
3403 | debug_generic_stmt (phi); | |
3404 | debug_generic_stmt (addr); | |
3405 | err |= true; | |
3406 | } | |
3407 | } | |
3408 | } | |
3409 | ||
3410 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3411 | { | |
3412 | tree stmt = bsi_stmt (bsi); | |
3413 | err |= verify_stmt (stmt); | |
3414 | addr = walk_tree (&stmt, verify_node_sharing, htab, NULL); | |
3415 | if (addr) | |
3416 | { | |
3417 | error ("Incorrect sharing of tree nodes"); | |
3418 | debug_generic_stmt (stmt); | |
3419 | debug_generic_stmt (addr); | |
3420 | err |= true; | |
3421 | } | |
3422 | } | |
3423 | } | |
3424 | ||
3425 | if (err) | |
3426 | internal_error ("verify_stmts failed."); | |
3427 | ||
3428 | htab_delete (htab); | |
3429 | timevar_pop (TV_TREE_STMT_VERIFY); | |
3430 | } | |
3431 | ||
3432 | ||
3433 | /* Verifies that the flow information is OK. */ | |
3434 | ||
3435 | static int | |
3436 | tree_verify_flow_info (void) | |
3437 | { | |
3438 | int err = 0; | |
3439 | basic_block bb; | |
3440 | block_stmt_iterator bsi; | |
3441 | tree stmt; | |
3442 | edge e; | |
3443 | ||
3444 | if (ENTRY_BLOCK_PTR->stmt_list) | |
3445 | { | |
3446 | error ("ENTRY_BLOCK has a statement list associated with it\n"); | |
3447 | err = 1; | |
3448 | } | |
3449 | ||
3450 | if (EXIT_BLOCK_PTR->stmt_list) | |
3451 | { | |
3452 | error ("EXIT_BLOCK has a statement list associated with it\n"); | |
3453 | err = 1; | |
3454 | } | |
3455 | ||
3456 | for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next) | |
3457 | if (e->flags & EDGE_FALLTHRU) | |
3458 | { | |
3459 | error ("Fallthru to exit from bb %d\n", e->src->index); | |
3460 | err = 1; | |
3461 | } | |
3462 | ||
3463 | FOR_EACH_BB (bb) | |
3464 | { | |
3465 | bool found_ctrl_stmt = false; | |
3466 | ||
3467 | /* Skip labels on the start of basic block. */ | |
3468 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3469 | { | |
3470 | if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR) | |
3471 | break; | |
3472 | ||
3473 | if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb) | |
3474 | { | |
3475 | error ("Label %s to block does not match in bb %d\n", | |
3476 | IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))), | |
3477 | bb->index); | |
3478 | err = 1; | |
3479 | } | |
3480 | ||
3481 | if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi))) | |
3482 | != current_function_decl) | |
3483 | { | |
3484 | error ("Label %s has incorrect context in bb %d\n", | |
3485 | IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))), | |
3486 | bb->index); | |
3487 | err = 1; | |
3488 | } | |
3489 | } | |
3490 | ||
3491 | /* Verify that body of basic block BB is free of control flow. */ | |
3492 | for (; !bsi_end_p (bsi); bsi_next (&bsi)) | |
3493 | { | |
3494 | tree stmt = bsi_stmt (bsi); | |
3495 | ||
3496 | if (found_ctrl_stmt) | |
3497 | { | |
3498 | error ("Control flow in the middle of basic block %d\n", | |
3499 | bb->index); | |
3500 | err = 1; | |
3501 | } | |
3502 | ||
3503 | if (stmt_ends_bb_p (stmt)) | |
3504 | found_ctrl_stmt = true; | |
3505 | ||
3506 | if (TREE_CODE (stmt) == LABEL_EXPR) | |
3507 | { | |
3508 | error ("Label %s in the middle of basic block %d\n", | |
3509 | IDENTIFIER_POINTER (DECL_NAME (stmt)), | |
3510 | bb->index); | |
3511 | err = 1; | |
3512 | } | |
3513 | } | |
3514 | bsi = bsi_last (bb); | |
3515 | if (bsi_end_p (bsi)) | |
3516 | continue; | |
3517 | ||
3518 | stmt = bsi_stmt (bsi); | |
3519 | ||
3520 | if (is_ctrl_stmt (stmt)) | |
3521 | { | |
3522 | for (e = bb->succ; e; e = e->succ_next) | |
3523 | if (e->flags & EDGE_FALLTHRU) | |
3524 | { | |
3525 | error ("Fallthru edge after a control statement in bb %d \n", | |
3526 | bb->index); | |
3527 | err = 1; | |
3528 | } | |
3529 | } | |
3530 | ||
3531 | switch (TREE_CODE (stmt)) | |
3532 | { | |
3533 | case COND_EXPR: | |
3534 | { | |
3535 | edge true_edge; | |
3536 | edge false_edge; | |
3537 | if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR | |
3538 | || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR) | |
3539 | { | |
3540 | error ("Structured COND_EXPR at the end of bb %d\n", bb->index); | |
3541 | err = 1; | |
3542 | } | |
3543 | ||
3544 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
3545 | ||
3546 | if (!true_edge || !false_edge | |
3547 | || !(true_edge->flags & EDGE_TRUE_VALUE) | |
3548 | || !(false_edge->flags & EDGE_FALSE_VALUE) | |
3549 | || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) | |
3550 | || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) | |
3551 | || bb->succ->succ_next->succ_next) | |
3552 | { | |
3553 | error ("Wrong outgoing edge flags at end of bb %d\n", | |
3554 | bb->index); | |
3555 | err = 1; | |
3556 | } | |
3557 | ||
3558 | if (!has_label_p (true_edge->dest, | |
3559 | GOTO_DESTINATION (COND_EXPR_THEN (stmt)))) | |
3560 | { | |
3561 | error ("`then' label does not match edge at end of bb %d\n", | |
3562 | bb->index); | |
3563 | err = 1; | |
3564 | } | |
3565 | ||
3566 | if (!has_label_p (false_edge->dest, | |
3567 | GOTO_DESTINATION (COND_EXPR_ELSE (stmt)))) | |
3568 | { | |
3569 | error ("`else' label does not match edge at end of bb %d\n", | |
3570 | bb->index); | |
3571 | err = 1; | |
3572 | } | |
3573 | } | |
3574 | break; | |
3575 | ||
3576 | case GOTO_EXPR: | |
3577 | if (simple_goto_p (stmt)) | |
3578 | { | |
3579 | error ("Explicit goto at end of bb %d\n", bb->index); | |
3580 | err = 1; | |
3581 | } | |
3582 | else | |
3583 | { | |
3584 | /* FIXME. We should double check that the labels in the | |
3585 | destination blocks have their address taken. */ | |
3586 | for (e = bb->succ; e; e = e->succ_next) | |
3587 | if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE | |
3588 | | EDGE_FALSE_VALUE)) | |
3589 | || !(e->flags & EDGE_ABNORMAL)) | |
3590 | { | |
3591 | error ("Wrong outgoing edge flags at end of bb %d\n", | |
3592 | bb->index); | |
3593 | err = 1; | |
3594 | } | |
3595 | } | |
3596 | break; | |
3597 | ||
3598 | case RETURN_EXPR: | |
3599 | if (!bb->succ || bb->succ->succ_next | |
3600 | || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL | |
3601 | | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
3602 | { | |
3603 | error ("Wrong outgoing edge flags at end of bb %d\n", bb->index); | |
3604 | err = 1; | |
3605 | } | |
3606 | if (bb->succ->dest != EXIT_BLOCK_PTR) | |
3607 | { | |
3608 | error ("Return edge does not point to exit in bb %d\n", | |
3609 | bb->index); | |
3610 | err = 1; | |
3611 | } | |
3612 | break; | |
3613 | ||
3614 | case SWITCH_EXPR: | |
3615 | { | |
7853504d | 3616 | tree prev; |
6de9cd9a DN |
3617 | edge e; |
3618 | size_t i, n; | |
3619 | tree vec; | |
3620 | ||
3621 | vec = SWITCH_LABELS (stmt); | |
3622 | n = TREE_VEC_LENGTH (vec); | |
3623 | ||
3624 | /* Mark all the destination basic blocks. */ | |
3625 | for (i = 0; i < n; ++i) | |
3626 | { | |
3627 | tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
3628 | basic_block label_bb = label_to_block (lab); | |
3629 | ||
3630 | if (label_bb->aux && label_bb->aux != (void *)1) | |
3631 | abort (); | |
3632 | label_bb->aux = (void *)1; | |
3633 | } | |
3634 | ||
7853504d SB |
3635 | /* Verify that the case labels are sorted. */ |
3636 | prev = TREE_VEC_ELT (vec, 0); | |
3637 | for (i = 1; i < n - 1; ++i) | |
3638 | { | |
3639 | tree c = TREE_VEC_ELT (vec, i); | |
3640 | if (! CASE_LOW (c)) | |
3641 | { | |
3642 | error ("Found default case not at end of case vector"); | |
3643 | err = 1; | |
3644 | continue; | |
3645 | } | |
3646 | if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c))) | |
3647 | { | |
3648 | error ("Case labels not sorted:\n "); | |
3649 | print_generic_expr (stderr, prev, 0); | |
3650 | fprintf (stderr," is greater than "); | |
3651 | print_generic_expr (stderr, c, 0); | |
3652 | fprintf (stderr," but comes before it.\n"); | |
3653 | err = 1; | |
3654 | } | |
3655 | prev = c; | |
3656 | } | |
3657 | if (CASE_LOW (TREE_VEC_ELT (vec, n - 1))) | |
3658 | { | |
3659 | error ("No default case found at end of case vector"); | |
3660 | err = 1; | |
3661 | } | |
3662 | ||
6de9cd9a DN |
3663 | for (e = bb->succ; e; e = e->succ_next) |
3664 | { | |
3665 | if (!e->dest->aux) | |
3666 | { | |
3667 | error ("Extra outgoing edge %d->%d\n", | |
3668 | bb->index, e->dest->index); | |
3669 | err = 1; | |
3670 | } | |
3671 | e->dest->aux = (void *)2; | |
3672 | if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL | |
3673 | | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
3674 | { | |
3675 | error ("Wrong outgoing edge flags at end of bb %d\n", | |
3676 | bb->index); | |
3677 | err = 1; | |
3678 | } | |
3679 | } | |
3680 | ||
3681 | /* Check that we have all of them. */ | |
3682 | for (i = 0; i < n; ++i) | |
3683 | { | |
3684 | tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
3685 | basic_block label_bb = label_to_block (lab); | |
3686 | ||
3687 | if (label_bb->aux != (void *)2) | |
3688 | { | |
3689 | error ("Missing edge %i->%i\n", | |
3690 | bb->index, label_bb->index); | |
3691 | err = 1; | |
3692 | } | |
3693 | } | |
3694 | ||
3695 | for (e = bb->succ; e; e = e->succ_next) | |
3696 | e->dest->aux = (void *)0; | |
3697 | } | |
3698 | ||
3699 | default: ; | |
3700 | } | |
3701 | } | |
3702 | ||
3703 | if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY) | |
3704 | verify_dominators (CDI_DOMINATORS); | |
3705 | ||
3706 | return err; | |
3707 | } | |
3708 | ||
3709 | ||
3710 | /* Updates phi nodes after creating forwarder block joined | |
3711 | by edge FALLTHRU. */ | |
3712 | ||
3713 | static void | |
3714 | tree_make_forwarder_block (edge fallthru) | |
3715 | { | |
3716 | edge e; | |
3717 | basic_block dummy, bb; | |
17192884 | 3718 | tree phi, new_phi, var, prev, next; |
6de9cd9a DN |
3719 | |
3720 | dummy = fallthru->src; | |
3721 | bb = fallthru->dest; | |
3722 | ||
3723 | if (!bb->pred->pred_next) | |
3724 | return; | |
3725 | ||
3726 | /* If we redirected a branch we must create new phi nodes at the | |
3727 | start of BB. */ | |
17192884 | 3728 | for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3729 | { |
3730 | var = PHI_RESULT (phi); | |
3731 | new_phi = create_phi_node (var, bb); | |
3732 | SSA_NAME_DEF_STMT (var) = new_phi; | |
d00ad49b | 3733 | SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi)); |
6de9cd9a DN |
3734 | add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru); |
3735 | } | |
3736 | ||
17192884 SB |
3737 | /* Ensure that the PHI node chain is in the same order. */ |
3738 | prev = NULL; | |
3739 | for (phi = phi_nodes (bb); phi; phi = next) | |
3740 | { | |
3741 | next = PHI_CHAIN (phi); | |
3742 | PHI_CHAIN (phi) = prev; | |
3743 | prev = phi; | |
3744 | } | |
3745 | set_phi_nodes (bb, prev); | |
6de9cd9a DN |
3746 | |
3747 | /* Add the arguments we have stored on edges. */ | |
3748 | for (e = bb->pred; e; e = e->pred_next) | |
3749 | { | |
3750 | if (e == fallthru) | |
3751 | continue; | |
3752 | ||
3753 | for (phi = phi_nodes (bb), var = PENDING_STMT (e); | |
3754 | phi; | |
17192884 | 3755 | phi = PHI_CHAIN (phi), var = TREE_CHAIN (var)) |
6de9cd9a DN |
3756 | add_phi_arg (&phi, TREE_VALUE (var), e); |
3757 | ||
3758 | PENDING_STMT (e) = NULL; | |
3759 | } | |
3760 | } | |
3761 | ||
3762 | ||
3763 | /* Return true if basic block BB does nothing except pass control | |
3764 | flow to another block and that we can safely insert a label at | |
3765 | the start of the successor block. */ | |
3766 | ||
3767 | static bool | |
3768 | tree_forwarder_block_p (basic_block bb) | |
3769 | { | |
3770 | block_stmt_iterator bsi; | |
3771 | edge e; | |
3772 | ||
3773 | /* If we have already determined that this block is not forwardable, | |
3774 | then no further checks are necessary. */ | |
3775 | if (! bb_ann (bb)->forwardable) | |
3776 | return false; | |
3777 | ||
3778 | /* BB must have a single outgoing normal edge. Otherwise it can not be | |
3779 | a forwarder block. */ | |
3780 | if (!bb->succ | |
3781 | || bb->succ->succ_next | |
3782 | || bb->succ->dest == EXIT_BLOCK_PTR | |
3783 | || (bb->succ->flags & EDGE_ABNORMAL) | |
3784 | || bb == ENTRY_BLOCK_PTR) | |
3785 | { | |
3786 | bb_ann (bb)->forwardable = 0; | |
3787 | return false; | |
3788 | } | |
3789 | ||
3790 | /* Successors of the entry block are not forwarders. */ | |
3791 | for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) | |
3792 | if (e->dest == bb) | |
3793 | { | |
3794 | bb_ann (bb)->forwardable = 0; | |
3795 | return false; | |
3796 | } | |
3797 | ||
3798 | /* BB can not have any PHI nodes. This could potentially be relaxed | |
3799 | early in compilation if we re-rewrote the variables appearing in | |
3800 | any PHI nodes in forwarder blocks. */ | |
3801 | if (phi_nodes (bb)) | |
3802 | { | |
3803 | bb_ann (bb)->forwardable = 0; | |
3804 | return false; | |
3805 | } | |
3806 | ||
3807 | /* Now walk through the statements. We can ignore labels, anything else | |
3808 | means this is not a forwarder block. */ | |
3809 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3810 | { | |
3811 | tree stmt = bsi_stmt (bsi); | |
3812 | ||
3813 | switch (TREE_CODE (stmt)) | |
3814 | { | |
3815 | case LABEL_EXPR: | |
3816 | if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) | |
3817 | return false; | |
3818 | break; | |
3819 | ||
3820 | default: | |
3821 | bb_ann (bb)->forwardable = 0; | |
3822 | return false; | |
3823 | } | |
3824 | } | |
3825 | ||
3826 | return true; | |
3827 | } | |
3828 | ||
3829 | ||
3830 | /* Thread jumps over empty statements. | |
3831 | ||
3832 | This code should _not_ thread over obviously equivalent conditions | |
3833 | as that requires nontrivial updates to the SSA graph. */ | |
3834 | ||
3835 | static bool | |
3836 | thread_jumps (void) | |
3837 | { | |
3838 | edge e, next, last, old; | |
3839 | basic_block bb, dest, tmp; | |
3840 | tree phi; | |
3841 | int arg; | |
3842 | bool retval = false; | |
3843 | ||
3844 | FOR_EACH_BB (bb) | |
3845 | bb_ann (bb)->forwardable = 1; | |
3846 | ||
3847 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb) | |
3848 | { | |
3849 | /* Don't waste time on unreachable blocks. */ | |
3850 | if (!bb->pred) | |
3851 | continue; | |
3852 | ||
3853 | /* Nor on forwarders. */ | |
3854 | if (tree_forwarder_block_p (bb)) | |
3855 | continue; | |
3856 | ||
3857 | /* This block is now part of a forwarding path, mark it as not | |
3858 | forwardable so that we can detect loops. This bit will be | |
3859 | reset below. */ | |
3860 | bb_ann (bb)->forwardable = 0; | |
3861 | ||
3862 | /* Examine each of our block's successors to see if it is | |
3863 | forwardable. */ | |
3864 | for (e = bb->succ; e; e = next) | |
3865 | { | |
3866 | next = e->succ_next; | |
3867 | ||
3868 | /* If the edge is abnormal or its destination is not | |
3869 | forwardable, then there's nothing to do. */ | |
3870 | if ((e->flags & EDGE_ABNORMAL) | |
3871 | || !tree_forwarder_block_p (e->dest)) | |
3872 | continue; | |
3873 | ||
3874 | /* Now walk through as many forwarder block as possible to | |
3875 | find the ultimate destination we want to thread our jump | |
3876 | to. */ | |
3877 | last = e->dest->succ; | |
3878 | bb_ann (e->dest)->forwardable = 0; | |
3879 | for (dest = e->dest->succ->dest; | |
3880 | tree_forwarder_block_p (dest); | |
3881 | last = dest->succ, | |
3882 | dest = dest->succ->dest) | |
3883 | { | |
3884 | /* An infinite loop detected. We redirect the edge anyway, so | |
3885 | that the loop is shrinked into single basic block. */ | |
3886 | if (!bb_ann (dest)->forwardable) | |
3887 | break; | |
3888 | ||
3889 | if (dest->succ->dest == EXIT_BLOCK_PTR) | |
3890 | break; | |
3891 | ||
3892 | bb_ann (dest)->forwardable = 0; | |
3893 | } | |
3894 | ||
3895 | /* Reset the forwardable marks to 1. */ | |
3896 | for (tmp = e->dest; | |
3897 | tmp != dest; | |
3898 | tmp = tmp->succ->dest) | |
3899 | bb_ann (tmp)->forwardable = 1; | |
3900 | ||
3901 | if (dest == e->dest) | |
3902 | continue; | |
3903 | ||
3904 | old = find_edge (bb, dest); | |
3905 | if (old) | |
3906 | { | |
3907 | /* If there already is an edge, check whether the values | |
3908 | in phi nodes differ. */ | |
3909 | if (!phi_alternatives_equal (dest, last, old)) | |
3910 | { | |
3911 | /* The previous block is forwarder. Redirect our jump | |
3912 | to that target instead since we know it has no PHI | |
3913 | nodes that will need updating. */ | |
3914 | dest = last->src; | |
3915 | ||
3916 | /* That might mean that no forwarding at all is possible. */ | |
3917 | if (dest == e->dest) | |
3918 | continue; | |
3919 | ||
3920 | old = find_edge (bb, dest); | |
3921 | } | |
3922 | } | |
3923 | ||
3924 | /* Perform the redirection. */ | |
3925 | retval = true; | |
3926 | e = redirect_edge_and_branch (e, dest); | |
3927 | ||
3928 | /* TODO -- updating dominators in this case is simple. */ | |
3929 | free_dominance_info (CDI_DOMINATORS); | |
3930 | ||
3931 | if (!old) | |
3932 | { | |
3933 | /* Update PHI nodes. We know that the new argument should | |
3934 | have the same value as the argument associated with LAST. | |
3935 | Otherwise we would have changed our target block above. */ | |
17192884 | 3936 | for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3937 | { |
3938 | arg = phi_arg_from_edge (phi, last); | |
3939 | if (arg < 0) | |
3940 | abort (); | |
3941 | add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e); | |
3942 | } | |
3943 | } | |
3944 | } | |
3945 | ||
3946 | /* Reset the forwardable bit on our block since it's no longer in | |
3947 | a forwarding chain path. */ | |
3948 | bb_ann (bb)->forwardable = 1; | |
3949 | } | |
3950 | ||
3951 | return retval; | |
3952 | } | |
3953 | ||
3954 | ||
3955 | /* Return a non-special label in the head of basic block BLOCK. | |
3956 | Create one if it doesn't exist. */ | |
3957 | ||
d7621d3c | 3958 | tree |
6de9cd9a DN |
3959 | tree_block_label (basic_block bb) |
3960 | { | |
3961 | block_stmt_iterator i, s = bsi_start (bb); | |
3962 | bool first = true; | |
3963 | tree label, stmt; | |
3964 | ||
3965 | for (i = s; !bsi_end_p (i); first = false, bsi_next (&i)) | |
3966 | { | |
3967 | stmt = bsi_stmt (i); | |
3968 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
3969 | break; | |
3970 | label = LABEL_EXPR_LABEL (stmt); | |
3971 | if (!DECL_NONLOCAL (label)) | |
3972 | { | |
3973 | if (!first) | |
3974 | bsi_move_before (&i, &s); | |
3975 | return label; | |
3976 | } | |
3977 | } | |
3978 | ||
3979 | label = create_artificial_label (); | |
3980 | stmt = build1 (LABEL_EXPR, void_type_node, label); | |
3981 | bsi_insert_before (&s, stmt, BSI_NEW_STMT); | |
3982 | return label; | |
3983 | } | |
3984 | ||
3985 | ||
3986 | /* Attempt to perform edge redirection by replacing a possibly complex | |
3987 | jump instruction by a goto or by removing the jump completely. | |
3988 | This can apply only if all edges now point to the same block. The | |
3989 | parameters and return values are equivalent to | |
3990 | redirect_edge_and_branch. */ | |
3991 | ||
3992 | static edge | |
3993 | tree_try_redirect_by_replacing_jump (edge e, basic_block target) | |
3994 | { | |
3995 | basic_block src = e->src; | |
3996 | edge tmp; | |
3997 | block_stmt_iterator b; | |
3998 | tree stmt; | |
3999 | ||
4000 | /* Verify that all targets will be TARGET. */ | |
4001 | for (tmp = src->succ; tmp; tmp = tmp->succ_next) | |
4002 | if (tmp->dest != target && tmp != e) | |
4003 | break; | |
4004 | ||
4005 | if (tmp) | |
4006 | return NULL; | |
4007 | ||
4008 | b = bsi_last (src); | |
4009 | if (bsi_end_p (b)) | |
4010 | return NULL; | |
4011 | stmt = bsi_stmt (b); | |
4012 | ||
4013 | if (TREE_CODE (stmt) == COND_EXPR | |
4014 | || TREE_CODE (stmt) == SWITCH_EXPR) | |
4015 | { | |
4016 | bsi_remove (&b); | |
4017 | e = ssa_redirect_edge (e, target); | |
4018 | e->flags = EDGE_FALLTHRU; | |
4019 | return e; | |
4020 | } | |
4021 | ||
4022 | return NULL; | |
4023 | } | |
4024 | ||
4025 | ||
4026 | /* Redirect E to DEST. Return NULL on failure. Otherwise, return the | |
4027 | edge representing the redirected branch. */ | |
4028 | ||
4029 | static edge | |
4030 | tree_redirect_edge_and_branch (edge e, basic_block dest) | |
4031 | { | |
4032 | basic_block bb = e->src; | |
4033 | block_stmt_iterator bsi; | |
4034 | edge ret; | |
4035 | tree label, stmt; | |
4036 | ||
4037 | if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) | |
4038 | return NULL; | |
4039 | ||
4040 | if (e->src != ENTRY_BLOCK_PTR | |
4041 | && (ret = tree_try_redirect_by_replacing_jump (e, dest))) | |
4042 | return ret; | |
4043 | ||
4044 | if (e->dest == dest) | |
4045 | return NULL; | |
4046 | ||
4047 | label = tree_block_label (dest); | |
4048 | ||
4049 | bsi = bsi_last (bb); | |
4050 | stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi); | |
4051 | ||
4052 | switch (stmt ? TREE_CODE (stmt) : ERROR_MARK) | |
4053 | { | |
4054 | case COND_EXPR: | |
4055 | stmt = (e->flags & EDGE_TRUE_VALUE | |
4056 | ? COND_EXPR_THEN (stmt) | |
4057 | : COND_EXPR_ELSE (stmt)); | |
4058 | GOTO_DESTINATION (stmt) = label; | |
4059 | break; | |
4060 | ||
4061 | case GOTO_EXPR: | |
4062 | /* No non-abnormal edges should lead from a non-simple goto, and | |
4063 | simple ones should be represented implicitly. */ | |
4064 | abort (); | |
4065 | ||
4066 | case SWITCH_EXPR: | |
4067 | { | |
4068 | tree vec = SWITCH_LABELS (stmt); | |
4069 | size_t i, n = TREE_VEC_LENGTH (vec); | |
4070 | ||
4071 | for (i = 0; i < n; ++i) | |
4072 | { | |
4073 | tree elt = TREE_VEC_ELT (vec, i); | |
4074 | if (label_to_block (CASE_LABEL (elt)) == e->dest) | |
4075 | CASE_LABEL (elt) = label; | |
4076 | } | |
4077 | } | |
4078 | break; | |
4079 | ||
4080 | case RETURN_EXPR: | |
4081 | bsi_remove (&bsi); | |
4082 | e->flags |= EDGE_FALLTHRU; | |
4083 | break; | |
4084 | ||
4085 | default: | |
4086 | /* Otherwise it must be a fallthru edge, and we don't need to | |
4087 | do anything besides redirecting it. */ | |
4088 | if (!(e->flags & EDGE_FALLTHRU)) | |
4089 | abort (); | |
4090 | break; | |
4091 | } | |
4092 | ||
4093 | /* Update/insert PHI nodes as necessary. */ | |
4094 | ||
4095 | /* Now update the edges in the CFG. */ | |
4096 | e = ssa_redirect_edge (e, dest); | |
4097 | ||
4098 | return e; | |
4099 | } | |
4100 | ||
4101 | ||
4102 | /* Simple wrapper, as we can always redirect fallthru edges. */ | |
4103 | ||
4104 | static basic_block | |
4105 | tree_redirect_edge_and_branch_force (edge e, basic_block dest) | |
4106 | { | |
4107 | e = tree_redirect_edge_and_branch (e, dest); | |
4108 | if (!e) | |
4109 | abort (); | |
4110 | ||
4111 | return NULL; | |
4112 | } | |
4113 | ||
4114 | ||
4115 | /* Splits basic block BB after statement STMT (but at least after the | |
4116 | labels). If STMT is NULL, BB is split just after the labels. */ | |
4117 | ||
4118 | static basic_block | |
4119 | tree_split_block (basic_block bb, void *stmt) | |
4120 | { | |
4121 | block_stmt_iterator bsi, bsi_tgt; | |
4122 | tree act; | |
4123 | basic_block new_bb; | |
4124 | edge e; | |
4125 | ||
4126 | new_bb = create_empty_bb (bb); | |
4127 | ||
4128 | /* Redirect the outgoing edges. */ | |
4129 | new_bb->succ = bb->succ; | |
4130 | bb->succ = NULL; | |
4131 | for (e = new_bb->succ; e; e = e->succ_next) | |
4132 | e->src = new_bb; | |
4133 | ||
4134 | if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR) | |
4135 | stmt = NULL; | |
4136 | ||
4137 | /* Move everything from BSI to the new basic block. */ | |
4138 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
4139 | { | |
4140 | act = bsi_stmt (bsi); | |
4141 | if (TREE_CODE (act) == LABEL_EXPR) | |
4142 | continue; | |
4143 | ||
4144 | if (!stmt) | |
4145 | break; | |
4146 | ||
4147 | if (stmt == act) | |
4148 | { | |
4149 | bsi_next (&bsi); | |
4150 | break; | |
4151 | } | |
4152 | } | |
4153 | ||
4154 | bsi_tgt = bsi_start (new_bb); | |
4155 | while (!bsi_end_p (bsi)) | |
4156 | { | |
4157 | act = bsi_stmt (bsi); | |
4158 | bsi_remove (&bsi); | |
4159 | bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT); | |
4160 | } | |
4161 | ||
4162 | return new_bb; | |
4163 | } | |
4164 | ||
4165 | ||
4166 | /* Moves basic block BB after block AFTER. */ | |
4167 | ||
4168 | static bool | |
4169 | tree_move_block_after (basic_block bb, basic_block after) | |
4170 | { | |
4171 | if (bb->prev_bb == after) | |
4172 | return true; | |
4173 | ||
4174 | unlink_block (bb); | |
4175 | link_block (bb, after); | |
4176 | ||
4177 | return true; | |
4178 | } | |
4179 | ||
4180 | ||
4181 | /* Return true if basic_block can be duplicated. */ | |
4182 | ||
4183 | static bool | |
4184 | tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED) | |
4185 | { | |
4186 | return true; | |
4187 | } | |
4188 | ||
4189 | ||
4190 | /* Create a duplicate of the basic block BB. NOTE: This does not | |
4191 | preserve SSA form. */ | |
4192 | ||
4193 | static basic_block | |
4194 | tree_duplicate_bb (basic_block bb) | |
4195 | { | |
4196 | basic_block new_bb; | |
4197 | block_stmt_iterator bsi, bsi_tgt; | |
4198 | ||
4199 | new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb); | |
4200 | bsi_tgt = bsi_start (new_bb); | |
4201 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
4202 | { | |
4203 | tree stmt = bsi_stmt (bsi); | |
4204 | ||
4205 | if (TREE_CODE (stmt) == LABEL_EXPR) | |
4206 | continue; | |
4207 | ||
4208 | bsi_insert_after (&bsi_tgt, unshare_expr (stmt), BSI_NEW_STMT); | |
4209 | } | |
4210 | ||
4211 | return new_bb; | |
4212 | } | |
4213 | ||
4214 | ||
4215 | /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */ | |
4216 | ||
4217 | void | |
4218 | dump_function_to_file (tree fn, FILE *file, int flags) | |
4219 | { | |
4220 | tree arg, vars, var; | |
4221 | bool ignore_topmost_bind = false, any_var = false; | |
4222 | basic_block bb; | |
4223 | tree chain; | |
4224 | ||
673fda6b | 4225 | fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2)); |
6de9cd9a DN |
4226 | |
4227 | arg = DECL_ARGUMENTS (fn); | |
4228 | while (arg) | |
4229 | { | |
4230 | print_generic_expr (file, arg, dump_flags); | |
4231 | if (TREE_CHAIN (arg)) | |
4232 | fprintf (file, ", "); | |
4233 | arg = TREE_CHAIN (arg); | |
4234 | } | |
4235 | fprintf (file, ")\n"); | |
4236 | ||
4237 | if (flags & TDF_RAW) | |
4238 | { | |
4239 | dump_node (fn, TDF_SLIM | flags, file); | |
4240 | return; | |
4241 | } | |
4242 | ||
4243 | /* When GIMPLE is lowered, the variables are no longer available in | |
4244 | BIND_EXPRs, so display them separately. */ | |
4245 | if (cfun && cfun->unexpanded_var_list) | |
4246 | { | |
4247 | ignore_topmost_bind = true; | |
4248 | ||
4249 | fprintf (file, "{\n"); | |
4250 | for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars)) | |
4251 | { | |
4252 | var = TREE_VALUE (vars); | |
4253 | ||
4254 | print_generic_decl (file, var, flags); | |
4255 | fprintf (file, "\n"); | |
4256 | ||
4257 | any_var = true; | |
4258 | } | |
4259 | } | |
4260 | ||
4261 | if (basic_block_info) | |
4262 | { | |
4263 | /* Make a CFG based dump. */ | |
4264 | if (!ignore_topmost_bind) | |
4265 | fprintf (file, "{\n"); | |
4266 | ||
4267 | if (any_var && n_basic_blocks) | |
4268 | fprintf (file, "\n"); | |
4269 | ||
4270 | FOR_EACH_BB (bb) | |
4271 | dump_generic_bb (file, bb, 2, flags); | |
4272 | ||
4273 | fprintf (file, "}\n"); | |
4274 | } | |
4275 | else | |
4276 | { | |
4277 | int indent; | |
4278 | ||
4279 | /* Make a tree based dump. */ | |
4280 | chain = DECL_SAVED_TREE (fn); | |
4281 | ||
4282 | if (TREE_CODE (chain) == BIND_EXPR) | |
4283 | { | |
4284 | if (ignore_topmost_bind) | |
4285 | { | |
4286 | chain = BIND_EXPR_BODY (chain); | |
4287 | indent = 2; | |
4288 | } | |
4289 | else | |
4290 | indent = 0; | |
4291 | } | |
4292 | else | |
4293 | { | |
4294 | if (!ignore_topmost_bind) | |
4295 | fprintf (file, "{\n"); | |
4296 | indent = 2; | |
4297 | } | |
4298 | ||
4299 | if (any_var) | |
4300 | fprintf (file, "\n"); | |
4301 | ||
4302 | print_generic_stmt_indented (file, chain, flags, indent); | |
4303 | if (ignore_topmost_bind) | |
4304 | fprintf (file, "}\n"); | |
4305 | } | |
4306 | ||
4307 | fprintf (file, "\n\n"); | |
4308 | } | |
4309 | ||
4310 | ||
4311 | /* Pretty print of the loops intermediate representation. */ | |
4312 | static void print_loop (FILE *, struct loop *, int); | |
4313 | static void print_pred_bbs (FILE *, edge); | |
4314 | static void print_succ_bbs (FILE *, edge); | |
4315 | ||
4316 | ||
4317 | /* Print the predecessors indexes of edge E on FILE. */ | |
4318 | ||
4319 | static void | |
4320 | print_pred_bbs (FILE *file, edge e) | |
4321 | { | |
4322 | if (e == NULL) | |
4323 | return; | |
4324 | ||
4325 | else if (e->pred_next == NULL) | |
4326 | fprintf (file, "bb_%d", e->src->index); | |
4327 | ||
4328 | else | |
4329 | { | |
4330 | fprintf (file, "bb_%d, ", e->src->index); | |
4331 | print_pred_bbs (file, e->pred_next); | |
4332 | } | |
4333 | } | |
4334 | ||
4335 | ||
4336 | /* Print the successors indexes of edge E on FILE. */ | |
4337 | ||
4338 | static void | |
4339 | print_succ_bbs (FILE *file, edge e) | |
4340 | { | |
4341 | if (e == NULL) | |
4342 | return; | |
4343 | else if (e->succ_next == NULL) | |
4344 | fprintf (file, "bb_%d", e->dest->index); | |
4345 | else | |
4346 | { | |
4347 | fprintf (file, "bb_%d, ", e->dest->index); | |
4348 | print_succ_bbs (file, e->succ_next); | |
4349 | } | |
4350 | } | |
4351 | ||
4352 | ||
4353 | /* Pretty print LOOP on FILE, indented INDENT spaces. */ | |
4354 | ||
4355 | static void | |
4356 | print_loop (FILE *file, struct loop *loop, int indent) | |
4357 | { | |
4358 | char *s_indent; | |
4359 | basic_block bb; | |
4360 | ||
4361 | if (loop == NULL) | |
4362 | return; | |
4363 | ||
4364 | s_indent = (char *) alloca ((size_t) indent + 1); | |
4365 | memset ((void *) s_indent, ' ', (size_t) indent); | |
4366 | s_indent[indent] = '\0'; | |
4367 | ||
4368 | /* Print the loop's header. */ | |
4369 | fprintf (file, "%sloop_%d\n", s_indent, loop->num); | |
4370 | ||
4371 | /* Print the loop's body. */ | |
4372 | fprintf (file, "%s{\n", s_indent); | |
4373 | FOR_EACH_BB (bb) | |
4374 | if (bb->loop_father == loop) | |
4375 | { | |
4376 | /* Print the basic_block's header. */ | |
4377 | fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index); | |
4378 | print_pred_bbs (file, bb->pred); | |
4379 | fprintf (file, "}, succs = {"); | |
4380 | print_succ_bbs (file, bb->succ); | |
4381 | fprintf (file, "})\n"); | |
4382 | ||
4383 | /* Print the basic_block's body. */ | |
4384 | fprintf (file, "%s {\n", s_indent); | |
4385 | tree_dump_bb (bb, file, indent + 4); | |
4386 | fprintf (file, "%s }\n", s_indent); | |
4387 | } | |
4388 | ||
4389 | print_loop (file, loop->inner, indent + 2); | |
4390 | fprintf (file, "%s}\n", s_indent); | |
4391 | print_loop (file, loop->next, indent); | |
4392 | } | |
4393 | ||
4394 | ||
4395 | /* Follow a CFG edge from the entry point of the program, and on entry | |
4396 | of a loop, pretty print the loop structure on FILE. */ | |
4397 | ||
4398 | void | |
4399 | print_loop_ir (FILE *file) | |
4400 | { | |
4401 | basic_block bb; | |
4402 | ||
4403 | bb = BASIC_BLOCK (0); | |
4404 | if (bb && bb->loop_father) | |
4405 | print_loop (file, bb->loop_father, 0); | |
4406 | } | |
4407 | ||
4408 | ||
4409 | /* Debugging loops structure at tree level. */ | |
4410 | ||
4411 | void | |
4412 | debug_loop_ir (void) | |
4413 | { | |
4414 | print_loop_ir (stderr); | |
4415 | } | |
4416 | ||
4417 | ||
4418 | /* Return true if BB ends with a call, possibly followed by some | |
4419 | instructions that must stay with the call. Return false, | |
4420 | otherwise. */ | |
4421 | ||
4422 | static bool | |
4423 | tree_block_ends_with_call_p (basic_block bb) | |
4424 | { | |
4425 | block_stmt_iterator bsi = bsi_last (bb); | |
4426 | tree t = tsi_stmt (bsi.tsi); | |
4427 | ||
4428 | if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)) | |
4429 | t = TREE_OPERAND (t, 0); | |
4430 | ||
4431 | if (TREE_CODE (t) == MODIFY_EXPR) | |
4432 | t = TREE_OPERAND (t, 1); | |
4433 | ||
4434 | return TREE_CODE (t) == CALL_EXPR; | |
4435 | } | |
4436 | ||
4437 | ||
4438 | /* Return true if BB ends with a conditional branch. Return false, | |
4439 | otherwise. */ | |
4440 | ||
4441 | static bool | |
4442 | tree_block_ends_with_condjump_p (basic_block bb) | |
4443 | { | |
4444 | tree stmt = tsi_stmt (bsi_last (bb).tsi); | |
4445 | return (TREE_CODE (stmt) == COND_EXPR); | |
4446 | } | |
4447 | ||
4448 | ||
4449 | /* Return true if we need to add fake edge to exit at statement T. | |
4450 | Helper function for tree_flow_call_edges_add. */ | |
4451 | ||
4452 | static bool | |
4453 | need_fake_edge_p (tree t) | |
4454 | { | |
4455 | if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)) | |
4456 | t = TREE_OPERAND (t, 0); | |
4457 | ||
4458 | if (TREE_CODE (t) == MODIFY_EXPR) | |
4459 | t = TREE_OPERAND (t, 1); | |
4460 | ||
4461 | /* NORETURN and LONGJMP calls already have an edge to exit. | |
4462 | CONST, PURE and ALWAYS_RETURN calls do not need one. | |
4463 | We don't currently check for CONST and PURE here, although | |
4464 | it would be a good idea, because those attributes are | |
4465 | figured out from the RTL in mark_constant_function, and | |
4466 | the counter incrementation code from -fprofile-arcs | |
4467 | leads to different results from -fbranch-probabilities. */ | |
4468 | if (TREE_CODE (t) == CALL_EXPR | |
4469 | && !(call_expr_flags (t) & | |
4470 | (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN))) | |
4471 | return true; | |
4472 | ||
4473 | if (TREE_CODE (t) == ASM_EXPR | |
4474 | && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t))) | |
4475 | return true; | |
4476 | ||
4477 | return false; | |
4478 | } | |
4479 | ||
4480 | ||
4481 | /* Add fake edges to the function exit for any non constant and non | |
4482 | noreturn calls, volatile inline assembly in the bitmap of blocks | |
4483 | specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return | |
4484 | the number of blocks that were split. | |
4485 | ||
4486 | The goal is to expose cases in which entering a basic block does | |
4487 | not imply that all subsequent instructions must be executed. */ | |
4488 | ||
4489 | static int | |
4490 | tree_flow_call_edges_add (sbitmap blocks) | |
4491 | { | |
4492 | int i; | |
4493 | int blocks_split = 0; | |
4494 | int last_bb = last_basic_block; | |
4495 | bool check_last_block = false; | |
4496 | ||
4497 | if (n_basic_blocks == 0) | |
4498 | return 0; | |
4499 | ||
4500 | if (! blocks) | |
4501 | check_last_block = true; | |
4502 | else | |
4503 | check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); | |
4504 | ||
4505 | /* In the last basic block, before epilogue generation, there will be | |
4506 | a fallthru edge to EXIT. Special care is required if the last insn | |
4507 | of the last basic block is a call because make_edge folds duplicate | |
4508 | edges, which would result in the fallthru edge also being marked | |
4509 | fake, which would result in the fallthru edge being removed by | |
4510 | remove_fake_edges, which would result in an invalid CFG. | |
4511 | ||
4512 | Moreover, we can't elide the outgoing fake edge, since the block | |
4513 | profiler needs to take this into account in order to solve the minimal | |
4514 | spanning tree in the case that the call doesn't return. | |
4515 | ||
4516 | Handle this by adding a dummy instruction in a new last basic block. */ | |
4517 | if (check_last_block) | |
4518 | { | |
4519 | basic_block bb = EXIT_BLOCK_PTR->prev_bb; | |
4520 | block_stmt_iterator bsi = bsi_last (bb); | |
4521 | tree t = NULL_TREE; | |
4522 | if (!bsi_end_p (bsi)) | |
4523 | t = bsi_stmt (bsi); | |
4524 | ||
4525 | if (need_fake_edge_p (t)) | |
4526 | { | |
4527 | edge e; | |
4528 | ||
4529 | for (e = bb->succ; e; e = e->succ_next) | |
4530 | if (e->dest == EXIT_BLOCK_PTR) | |
4531 | { | |
4532 | bsi_insert_on_edge (e, build_empty_stmt ()); | |
4533 | bsi_commit_edge_inserts ((int *)NULL); | |
4534 | break; | |
4535 | } | |
4536 | } | |
4537 | } | |
4538 | ||
4539 | /* Now add fake edges to the function exit for any non constant | |
4540 | calls since there is no way that we can determine if they will | |
4541 | return or not... */ | |
4542 | for (i = 0; i < last_bb; i++) | |
4543 | { | |
4544 | basic_block bb = BASIC_BLOCK (i); | |
4545 | block_stmt_iterator bsi; | |
4546 | tree stmt, last_stmt; | |
4547 | ||
4548 | if (!bb) | |
4549 | continue; | |
4550 | ||
4551 | if (blocks && !TEST_BIT (blocks, i)) | |
4552 | continue; | |
4553 | ||
4554 | bsi = bsi_last (bb); | |
4555 | if (!bsi_end_p (bsi)) | |
4556 | { | |
4557 | last_stmt = bsi_stmt (bsi); | |
4558 | do | |
4559 | { | |
4560 | stmt = bsi_stmt (bsi); | |
4561 | if (need_fake_edge_p (stmt)) | |
4562 | { | |
4563 | edge e; | |
4564 | /* The handling above of the final block before the | |
4565 | epilogue should be enough to verify that there is | |
4566 | no edge to the exit block in CFG already. | |
4567 | Calling make_edge in such case would cause us to | |
4568 | mark that edge as fake and remove it later. */ | |
4569 | #ifdef ENABLE_CHECKING | |
4570 | if (stmt == last_stmt) | |
4571 | for (e = bb->succ; e; e = e->succ_next) | |
4572 | if (e->dest == EXIT_BLOCK_PTR) | |
4573 | abort (); | |
4574 | #endif | |
4575 | ||
4576 | /* Note that the following may create a new basic block | |
4577 | and renumber the existing basic blocks. */ | |
4578 | if (stmt != last_stmt) | |
4579 | { | |
4580 | e = split_block (bb, stmt); | |
4581 | if (e) | |
4582 | blocks_split++; | |
4583 | } | |
4584 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
4585 | } | |
4586 | bsi_prev (&bsi); | |
4587 | } | |
4588 | while (!bsi_end_p (bsi)); | |
4589 | } | |
4590 | } | |
4591 | ||
4592 | if (blocks_split) | |
4593 | verify_flow_info (); | |
4594 | ||
4595 | return blocks_split; | |
4596 | } | |
4597 | ||
4598 | ||
4599 | struct cfg_hooks tree_cfg_hooks = { | |
4600 | "tree", | |
4601 | tree_verify_flow_info, | |
4602 | tree_dump_bb, /* dump_bb */ | |
4603 | create_bb, /* create_basic_block */ | |
4604 | tree_redirect_edge_and_branch,/* redirect_edge_and_branch */ | |
4605 | tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */ | |
4606 | remove_bb, /* delete_basic_block */ | |
4607 | tree_split_block, /* split_block */ | |
4608 | tree_move_block_after, /* move_block_after */ | |
4609 | tree_can_merge_blocks_p, /* can_merge_blocks_p */ | |
4610 | tree_merge_blocks, /* merge_blocks */ | |
4611 | tree_predict_edge, /* predict_edge */ | |
4612 | tree_predicted_by_p, /* predicted_by_p */ | |
4613 | tree_can_duplicate_bb_p, /* can_duplicate_block_p */ | |
4614 | tree_duplicate_bb, /* duplicate_block */ | |
4615 | tree_split_edge, /* split_edge */ | |
4616 | tree_make_forwarder_block, /* make_forward_block */ | |
4617 | NULL, /* tidy_fallthru_edge */ | |
4618 | tree_block_ends_with_call_p, /* block_ends_with_call_p */ | |
4619 | tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */ | |
4620 | tree_flow_call_edges_add /* flow_call_edges_add */ | |
4621 | }; | |
4622 | ||
4623 | ||
4624 | /* Split all critical edges. */ | |
4625 | ||
4626 | static void | |
4627 | split_critical_edges (void) | |
4628 | { | |
4629 | basic_block bb; | |
4630 | edge e; | |
4631 | ||
4632 | FOR_ALL_BB (bb) | |
4633 | { | |
4634 | for (e = bb->succ; e ; e = e->succ_next) | |
4635 | if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL)) | |
4636 | { | |
4637 | split_edge (e); | |
4638 | } | |
4639 | } | |
4640 | } | |
4641 | ||
4642 | struct tree_opt_pass pass_split_crit_edges = | |
4643 | { | |
5d44aeed | 4644 | "crited", /* name */ |
6de9cd9a DN |
4645 | NULL, /* gate */ |
4646 | split_critical_edges, /* execute */ | |
4647 | NULL, /* sub */ | |
4648 | NULL, /* next */ | |
4649 | 0, /* static_pass_number */ | |
4650 | TV_TREE_SPLIT_EDGES, /* tv_id */ | |
4651 | PROP_cfg, /* properties required */ | |
4652 | PROP_no_crit_edges, /* properties_provided */ | |
4653 | 0, /* properties_destroyed */ | |
4654 | 0, /* todo_flags_start */ | |
5d44aeed | 4655 | TODO_dump_func, /* todo_flags_finish */ |
6de9cd9a DN |
4656 | }; |
4657 | \f | |
4658 | /* Emit return warnings. */ | |
4659 | ||
4660 | static void | |
4661 | execute_warn_function_return (void) | |
4662 | { | |
4663 | location_t *locus; | |
4664 | tree last; | |
4665 | edge e; | |
4666 | ||
4667 | if (warn_missing_noreturn | |
4668 | && !TREE_THIS_VOLATILE (cfun->decl) | |
4669 | && EXIT_BLOCK_PTR->pred == NULL | |
4670 | && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl)) | |
4671 | warning ("%Jfunction might be possible candidate for attribute `noreturn'", | |
4672 | cfun->decl); | |
4673 | ||
4674 | /* If we have a path to EXIT, then we do return. */ | |
4675 | if (TREE_THIS_VOLATILE (cfun->decl) | |
4676 | && EXIT_BLOCK_PTR->pred != NULL) | |
4677 | { | |
4678 | locus = NULL; | |
4679 | for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next) | |
4680 | { | |
4681 | last = last_stmt (e->src); | |
4682 | if (TREE_CODE (last) == RETURN_EXPR | |
4683 | && (locus = EXPR_LOCUS (last)) != NULL) | |
4684 | break; | |
4685 | } | |
4686 | if (!locus) | |
4687 | locus = &cfun->function_end_locus; | |
4688 | warning ("%H`noreturn' function does return", locus); | |
4689 | } | |
4690 | ||
4691 | /* If we see "return;" in some basic block, then we do reach the end | |
4692 | without returning a value. */ | |
4693 | else if (warn_return_type | |
4694 | && EXIT_BLOCK_PTR->pred != NULL | |
4695 | && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl)))) | |
4696 | { | |
4697 | for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next) | |
4698 | { | |
4699 | tree last = last_stmt (e->src); | |
4700 | if (TREE_CODE (last) == RETURN_EXPR | |
4701 | && TREE_OPERAND (last, 0) == NULL) | |
4702 | { | |
4703 | locus = EXPR_LOCUS (last); | |
4704 | if (!locus) | |
4705 | locus = &cfun->function_end_locus; | |
4706 | warning ("%Hcontrol reaches end of non-void function", locus); | |
4707 | break; | |
4708 | } | |
4709 | } | |
4710 | } | |
4711 | } | |
4712 | ||
4713 | ||
4714 | /* Given a basic block B which ends with a conditional and has | |
4715 | precisely two successors, determine which of the edges is taken if | |
4716 | the conditional is true and which is taken if the conditional is | |
4717 | false. Set TRUE_EDGE and FALSE_EDGE appropriately. */ | |
4718 | ||
4719 | void | |
4720 | extract_true_false_edges_from_block (basic_block b, | |
4721 | edge *true_edge, | |
4722 | edge *false_edge) | |
4723 | { | |
4724 | edge e = b->succ; | |
4725 | ||
4726 | if (e->flags & EDGE_TRUE_VALUE) | |
4727 | { | |
4728 | *true_edge = e; | |
4729 | *false_edge = e->succ_next; | |
4730 | } | |
4731 | else | |
4732 | { | |
4733 | *false_edge = e; | |
4734 | *true_edge = e->succ_next; | |
4735 | } | |
4736 | } | |
4737 | ||
4738 | struct tree_opt_pass pass_warn_function_return = | |
4739 | { | |
4740 | NULL, /* name */ | |
4741 | NULL, /* gate */ | |
4742 | execute_warn_function_return, /* execute */ | |
4743 | NULL, /* sub */ | |
4744 | NULL, /* next */ | |
4745 | 0, /* static_pass_number */ | |
4746 | 0, /* tv_id */ | |
4747 | PROP_ssa, /* properties_required */ | |
4748 | 0, /* properties_provided */ | |
4749 | 0, /* properties_destroyed */ | |
4750 | 0, /* todo_flags_start */ | |
4751 | 0 /* todo_flags_finish */ | |
4752 | }; | |
4753 | ||
4754 | #include "gt-tree-cfg.h" |