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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); | |
77 | static tree tree_block_label (basic_block bb); | |
78 | ||
79 | /* Edges. */ | |
80 | static void make_edges (void); | |
81 | static void make_ctrl_stmt_edges (basic_block); | |
82 | static void make_exit_edges (basic_block); | |
83 | static void make_cond_expr_edges (basic_block); | |
84 | static void make_switch_expr_edges (basic_block); | |
85 | static void make_goto_expr_edges (basic_block); | |
86 | static edge tree_redirect_edge_and_branch (edge, basic_block); | |
87 | static edge tree_try_redirect_by_replacing_jump (edge, basic_block); | |
88 | static void split_critical_edges (void); | |
89 | ||
90 | /* Various helpers. */ | |
91 | static inline bool stmt_starts_bb_p (tree, tree); | |
92 | static int tree_verify_flow_info (void); | |
93 | static void tree_make_forwarder_block (edge); | |
94 | static bool thread_jumps (void); | |
95 | static bool tree_forwarder_block_p (basic_block); | |
96 | static void bsi_commit_edge_inserts_1 (edge e); | |
97 | static void tree_cfg2vcg (FILE *); | |
98 | ||
99 | /* Flowgraph optimization and cleanup. */ | |
100 | static void tree_merge_blocks (basic_block, basic_block); | |
101 | static bool tree_can_merge_blocks_p (basic_block, basic_block); | |
102 | static void remove_bb (basic_block); | |
f667741c | 103 | static void group_case_labels (void); |
6de9cd9a DN |
104 | static void cleanup_dead_labels (void); |
105 | static bool cleanup_control_flow (void); | |
106 | static bool cleanup_control_expr_graph (basic_block, block_stmt_iterator); | |
107 | static edge find_taken_edge_cond_expr (basic_block, tree); | |
108 | static edge find_taken_edge_switch_expr (basic_block, tree); | |
109 | static tree find_case_label_for_value (tree, tree); | |
110 | static bool phi_alternatives_equal (basic_block, edge, edge); | |
111 | ||
112 | ||
113 | /*--------------------------------------------------------------------------- | |
114 | Create basic blocks | |
115 | ---------------------------------------------------------------------------*/ | |
116 | ||
117 | /* Entry point to the CFG builder for trees. TP points to the list of | |
118 | statements to be added to the flowgraph. */ | |
119 | ||
120 | static void | |
121 | build_tree_cfg (tree *tp) | |
122 | { | |
123 | /* Register specific tree functions. */ | |
124 | tree_register_cfg_hooks (); | |
125 | ||
126 | /* Initialize rbi_pool. */ | |
127 | alloc_rbi_pool (); | |
128 | ||
129 | /* Initialize the basic block array. */ | |
130 | init_flow (); | |
131 | n_basic_blocks = 0; | |
132 | last_basic_block = 0; | |
133 | VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info"); | |
134 | memset ((void *) &cfg_stats, 0, sizeof (cfg_stats)); | |
135 | ||
136 | /* Build a mapping of labels to their associated blocks. */ | |
137 | VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity, | |
138 | "label to block map"); | |
139 | ||
140 | ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR; | |
141 | EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR; | |
142 | ||
143 | found_computed_goto = 0; | |
144 | make_blocks (*tp); | |
145 | ||
146 | /* Computed gotos are hell to deal with, especially if there are | |
147 | lots of them with a large number of destinations. So we factor | |
148 | them to a common computed goto location before we build the | |
149 | edge list. After we convert back to normal form, we will un-factor | |
150 | the computed gotos since factoring introduces an unwanted jump. */ | |
151 | if (found_computed_goto) | |
152 | factor_computed_gotos (); | |
153 | ||
154 | /* Make sure there is always at least one block, even if its empty. */ | |
155 | if (n_basic_blocks == 0) | |
156 | create_empty_bb (ENTRY_BLOCK_PTR); | |
157 | ||
158 | create_block_annotation (ENTRY_BLOCK_PTR); | |
159 | create_block_annotation (EXIT_BLOCK_PTR); | |
160 | ||
161 | /* Adjust the size of the array. */ | |
162 | VARRAY_GROW (basic_block_info, n_basic_blocks); | |
163 | ||
f667741c SB |
164 | /* To speed up statement iterator walks, we first purge dead labels. */ |
165 | cleanup_dead_labels (); | |
166 | ||
167 | /* Group case nodes to reduce the number of edges. | |
168 | We do this after cleaning up dead labels because otherwise we miss | |
169 | a lot of obvious case merging opportunities. */ | |
170 | group_case_labels (); | |
171 | ||
6de9cd9a DN |
172 | /* Create the edges of the flowgraph. */ |
173 | make_edges (); | |
174 | ||
175 | /* Debugging dumps. */ | |
176 | ||
177 | /* Write the flowgraph to a VCG file. */ | |
178 | { | |
179 | int local_dump_flags; | |
180 | FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags); | |
181 | if (dump_file) | |
182 | { | |
183 | tree_cfg2vcg (dump_file); | |
184 | dump_end (TDI_vcg, dump_file); | |
185 | } | |
186 | } | |
187 | ||
188 | /* Dump a textual representation of the flowgraph. */ | |
189 | if (dump_file) | |
190 | dump_tree_cfg (dump_file, dump_flags); | |
191 | } | |
192 | ||
193 | static void | |
194 | execute_build_cfg (void) | |
195 | { | |
196 | build_tree_cfg (&DECL_SAVED_TREE (current_function_decl)); | |
197 | } | |
198 | ||
199 | struct tree_opt_pass pass_build_cfg = | |
200 | { | |
201 | "cfg", /* name */ | |
202 | NULL, /* gate */ | |
203 | execute_build_cfg, /* execute */ | |
204 | NULL, /* sub */ | |
205 | NULL, /* next */ | |
206 | 0, /* static_pass_number */ | |
207 | TV_TREE_CFG, /* tv_id */ | |
208 | PROP_gimple_leh, /* properties_required */ | |
209 | PROP_cfg, /* properties_provided */ | |
210 | 0, /* properties_destroyed */ | |
211 | 0, /* todo_flags_start */ | |
212 | TODO_verify_stmts /* todo_flags_finish */ | |
213 | }; | |
214 | ||
215 | /* Search the CFG for any computed gotos. If found, factor them to a | |
216 | common computed goto site. Also record the location of that site so | |
217 | that we can un-factor the gotos after we have converted back to | |
218 | normal form. */ | |
219 | ||
220 | static void | |
221 | factor_computed_gotos (void) | |
222 | { | |
223 | basic_block bb; | |
224 | tree factored_label_decl = NULL; | |
225 | tree var = NULL; | |
226 | tree factored_computed_goto_label = NULL; | |
227 | tree factored_computed_goto = NULL; | |
228 | ||
229 | /* We know there are one or more computed gotos in this function. | |
230 | Examine the last statement in each basic block to see if the block | |
231 | ends with a computed goto. */ | |
232 | ||
233 | FOR_EACH_BB (bb) | |
234 | { | |
235 | block_stmt_iterator bsi = bsi_last (bb); | |
236 | tree last; | |
237 | ||
238 | if (bsi_end_p (bsi)) | |
239 | continue; | |
240 | last = bsi_stmt (bsi); | |
241 | ||
242 | /* Ignore the computed goto we create when we factor the original | |
243 | computed gotos. */ | |
244 | if (last == factored_computed_goto) | |
245 | continue; | |
246 | ||
247 | /* If the last statement is a computed goto, factor it. */ | |
248 | if (computed_goto_p (last)) | |
249 | { | |
250 | tree assignment; | |
251 | ||
252 | /* The first time we find a computed goto we need to create | |
253 | the factored goto block and the variable each original | |
254 | computed goto will use for their goto destination. */ | |
255 | if (! factored_computed_goto) | |
256 | { | |
257 | basic_block new_bb = create_empty_bb (bb); | |
258 | block_stmt_iterator new_bsi = bsi_start (new_bb); | |
259 | ||
260 | /* Create the destination of the factored goto. Each original | |
261 | computed goto will put its desired destination into this | |
262 | variable and jump to the label we create immediately | |
263 | below. */ | |
264 | var = create_tmp_var (ptr_type_node, "gotovar"); | |
265 | ||
266 | /* Build a label for the new block which will contain the | |
267 | factored computed goto. */ | |
268 | factored_label_decl = create_artificial_label (); | |
269 | factored_computed_goto_label | |
270 | = build1 (LABEL_EXPR, void_type_node, factored_label_decl); | |
271 | bsi_insert_after (&new_bsi, factored_computed_goto_label, | |
272 | BSI_NEW_STMT); | |
273 | ||
274 | /* Build our new computed goto. */ | |
275 | factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var); | |
276 | bsi_insert_after (&new_bsi, factored_computed_goto, | |
277 | BSI_NEW_STMT); | |
278 | } | |
279 | ||
280 | /* Copy the original computed goto's destination into VAR. */ | |
281 | assignment = build (MODIFY_EXPR, ptr_type_node, | |
282 | var, GOTO_DESTINATION (last)); | |
283 | bsi_insert_before (&bsi, assignment, BSI_SAME_STMT); | |
284 | ||
285 | /* And re-vector the computed goto to the new destination. */ | |
286 | GOTO_DESTINATION (last) = factored_label_decl; | |
287 | } | |
288 | } | |
289 | } | |
290 | ||
291 | ||
292 | /* Create annotations for a single basic block. */ | |
293 | ||
294 | static void | |
295 | create_block_annotation (basic_block bb) | |
296 | { | |
297 | /* Verify that the tree_annotations field is clear. */ | |
298 | if (bb->tree_annotations) | |
299 | abort (); | |
300 | bb->tree_annotations = ggc_alloc_cleared (sizeof (struct bb_ann_d)); | |
301 | } | |
302 | ||
303 | ||
304 | /* Free the annotations for all the basic blocks. */ | |
305 | ||
306 | static void free_blocks_annotations (void) | |
307 | { | |
308 | clear_blocks_annotations (); | |
309 | } | |
310 | ||
311 | ||
312 | /* Clear the annotations for all the basic blocks. */ | |
313 | ||
314 | static void | |
315 | clear_blocks_annotations (void) | |
316 | { | |
317 | basic_block bb; | |
318 | ||
319 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) | |
320 | bb->tree_annotations = NULL; | |
321 | } | |
322 | ||
323 | ||
324 | /* Build a flowgraph for the statement_list STMT_LIST. */ | |
325 | ||
326 | static void | |
327 | make_blocks (tree stmt_list) | |
328 | { | |
329 | tree_stmt_iterator i = tsi_start (stmt_list); | |
330 | tree stmt = NULL; | |
331 | bool start_new_block = true; | |
332 | bool first_stmt_of_list = true; | |
333 | basic_block bb = ENTRY_BLOCK_PTR; | |
334 | ||
335 | while (!tsi_end_p (i)) | |
336 | { | |
337 | tree prev_stmt; | |
338 | ||
339 | prev_stmt = stmt; | |
340 | stmt = tsi_stmt (i); | |
341 | ||
342 | /* If the statement starts a new basic block or if we have determined | |
343 | in a previous pass that we need to create a new block for STMT, do | |
344 | so now. */ | |
345 | if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt)) | |
346 | { | |
347 | if (!first_stmt_of_list) | |
348 | stmt_list = tsi_split_statement_list_before (&i); | |
349 | bb = create_basic_block (stmt_list, NULL, bb); | |
350 | start_new_block = false; | |
351 | } | |
352 | ||
353 | /* Now add STMT to BB and create the subgraphs for special statement | |
354 | codes. */ | |
355 | set_bb_for_stmt (stmt, bb); | |
356 | ||
357 | if (computed_goto_p (stmt)) | |
358 | found_computed_goto = true; | |
359 | ||
360 | /* If STMT is a basic block terminator, set START_NEW_BLOCK for the | |
361 | next iteration. */ | |
362 | if (stmt_ends_bb_p (stmt)) | |
363 | start_new_block = true; | |
364 | ||
365 | tsi_next (&i); | |
366 | first_stmt_of_list = false; | |
367 | } | |
368 | } | |
369 | ||
370 | ||
371 | /* Create and return a new empty basic block after bb AFTER. */ | |
372 | ||
373 | static basic_block | |
374 | create_bb (void *h, void *e, basic_block after) | |
375 | { | |
376 | basic_block bb; | |
377 | ||
378 | if (e) | |
379 | abort (); | |
380 | ||
381 | /* Create and initialize a new basic block. */ | |
382 | bb = alloc_block (); | |
383 | memset (bb, 0, sizeof (*bb)); | |
384 | ||
385 | bb->index = last_basic_block; | |
386 | bb->flags = BB_NEW; | |
387 | bb->stmt_list = h ? h : alloc_stmt_list (); | |
388 | ||
389 | /* Add the new block to the linked list of blocks. */ | |
390 | link_block (bb, after); | |
391 | ||
392 | /* Grow the basic block array if needed. */ | |
393 | if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info)) | |
394 | { | |
395 | size_t new_size = last_basic_block + (last_basic_block + 3) / 4; | |
396 | VARRAY_GROW (basic_block_info, new_size); | |
397 | } | |
398 | ||
399 | /* Add the newly created block to the array. */ | |
400 | BASIC_BLOCK (last_basic_block) = bb; | |
401 | ||
402 | create_block_annotation (bb); | |
403 | ||
404 | n_basic_blocks++; | |
405 | last_basic_block++; | |
406 | ||
407 | initialize_bb_rbi (bb); | |
408 | return bb; | |
409 | } | |
410 | ||
411 | ||
412 | /*--------------------------------------------------------------------------- | |
413 | Edge creation | |
414 | ---------------------------------------------------------------------------*/ | |
415 | ||
416 | /* Join all the blocks in the flowgraph. */ | |
417 | ||
418 | static void | |
419 | make_edges (void) | |
420 | { | |
421 | basic_block bb; | |
422 | edge e; | |
423 | ||
424 | /* Create an edge from entry to the first block with executable | |
425 | statements in it. */ | |
426 | make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU); | |
427 | ||
428 | /* Traverse basic block array placing edges. */ | |
429 | FOR_EACH_BB (bb) | |
430 | { | |
431 | tree first = first_stmt (bb); | |
432 | tree last = last_stmt (bb); | |
433 | ||
434 | if (first) | |
435 | { | |
436 | /* Edges for statements that always alter flow control. */ | |
437 | if (is_ctrl_stmt (last)) | |
438 | make_ctrl_stmt_edges (bb); | |
439 | ||
440 | /* Edges for statements that sometimes alter flow control. */ | |
441 | if (is_ctrl_altering_stmt (last)) | |
442 | make_exit_edges (bb); | |
443 | } | |
444 | ||
445 | /* Finally, if no edges were created above, this is a regular | |
446 | basic block that only needs a fallthru edge. */ | |
447 | if (bb->succ == NULL) | |
448 | make_edge (bb, bb->next_bb, EDGE_FALLTHRU); | |
449 | } | |
450 | ||
451 | /* If there is a fallthru edge to exit out of the last block, transform it | |
452 | to a return statement. */ | |
453 | for (e = EXIT_BLOCK_PTR->prev_bb->succ; e; e = e->succ_next) | |
454 | if (e->flags & EDGE_FALLTHRU) | |
455 | break; | |
456 | ||
457 | if (e && e->dest == EXIT_BLOCK_PTR) | |
458 | { | |
459 | block_stmt_iterator bsi; | |
460 | basic_block ret_bb = EXIT_BLOCK_PTR->prev_bb; | |
461 | tree x; | |
462 | ||
463 | /* If E->SRC ends with a call that has an abnormal edge (for EH or | |
464 | nonlocal goto), then we will need to split the edge to insert | |
465 | an explicit return statement. */ | |
466 | if (e != ret_bb->succ || e->succ_next) | |
467 | { | |
468 | ret_bb = split_edge (e); | |
469 | e = ret_bb->succ; | |
470 | } | |
471 | e->flags &= ~EDGE_FALLTHRU; | |
472 | ||
473 | x = build (RETURN_EXPR, void_type_node, NULL_TREE); | |
474 | bsi = bsi_last (ret_bb); | |
475 | bsi_insert_after (&bsi, x, BSI_NEW_STMT); | |
476 | } | |
477 | ||
478 | /* We do not care about fake edges, so remove any that the CFG | |
479 | builder inserted for completeness. */ | |
480 | remove_fake_edges (); | |
481 | ||
6de9cd9a DN |
482 | /* Clean up the graph and warn for unreachable code. */ |
483 | cleanup_tree_cfg (); | |
484 | } | |
485 | ||
486 | ||
487 | /* Create edges for control statement at basic block BB. */ | |
488 | ||
489 | static void | |
490 | make_ctrl_stmt_edges (basic_block bb) | |
491 | { | |
492 | tree last = last_stmt (bb); | |
493 | tree first = first_stmt (bb); | |
494 | ||
495 | #if defined ENABLE_CHECKING | |
496 | if (last == NULL_TREE) | |
497 | abort(); | |
498 | #endif | |
499 | ||
500 | if (TREE_CODE (first) == LABEL_EXPR | |
501 | && DECL_NONLOCAL (LABEL_EXPR_LABEL (first))) | |
502 | make_edge (ENTRY_BLOCK_PTR, bb, EDGE_ABNORMAL); | |
503 | ||
504 | switch (TREE_CODE (last)) | |
505 | { | |
506 | case GOTO_EXPR: | |
507 | make_goto_expr_edges (bb); | |
508 | break; | |
509 | ||
510 | case RETURN_EXPR: | |
511 | make_edge (bb, EXIT_BLOCK_PTR, 0); | |
512 | break; | |
513 | ||
514 | case COND_EXPR: | |
515 | make_cond_expr_edges (bb); | |
516 | break; | |
517 | ||
518 | case SWITCH_EXPR: | |
519 | make_switch_expr_edges (bb); | |
520 | break; | |
521 | ||
522 | case RESX_EXPR: | |
523 | make_eh_edges (last); | |
524 | /* Yet another NORETURN hack. */ | |
525 | if (bb->succ == NULL) | |
526 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
527 | break; | |
528 | ||
529 | default: | |
530 | abort (); | |
531 | } | |
532 | } | |
533 | ||
534 | ||
535 | /* Create exit edges for statements in block BB that alter the flow of | |
536 | control. Statements that alter the control flow are 'goto', 'return' | |
537 | and calls to non-returning functions. */ | |
538 | ||
539 | static void | |
540 | make_exit_edges (basic_block bb) | |
541 | { | |
542 | tree last = last_stmt (bb); | |
543 | ||
544 | if (last == NULL_TREE) | |
545 | abort (); | |
546 | ||
547 | switch (TREE_CODE (last)) | |
548 | { | |
549 | case CALL_EXPR: | |
550 | /* If this function receives a nonlocal goto, then we need to | |
551 | make edges from this call site to all the nonlocal goto | |
552 | handlers. */ | |
553 | if (TREE_SIDE_EFFECTS (last) | |
554 | && current_function_has_nonlocal_label) | |
555 | make_goto_expr_edges (bb); | |
556 | ||
557 | /* If this statement has reachable exception handlers, then | |
558 | create abnormal edges to them. */ | |
559 | make_eh_edges (last); | |
560 | ||
561 | /* Some calls are known not to return. For such calls we create | |
562 | a fake edge. | |
563 | ||
564 | We really need to revamp how we build edges so that it's not | |
565 | such a bloody pain to avoid creating edges for this case since | |
566 | all we do is remove these edges when we're done building the | |
567 | CFG. */ | |
568 | if (call_expr_flags (last) & (ECF_NORETURN | ECF_LONGJMP)) | |
569 | { | |
570 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
571 | return; | |
572 | } | |
573 | ||
574 | /* Don't forget the fall-thru edge. */ | |
575 | make_edge (bb, bb->next_bb, EDGE_FALLTHRU); | |
576 | break; | |
577 | ||
578 | case MODIFY_EXPR: | |
579 | /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR | |
580 | may have an abnormal edge. Search the RHS for this case and | |
581 | create any required edges. */ | |
582 | if (TREE_CODE (TREE_OPERAND (last, 1)) == CALL_EXPR | |
583 | && TREE_SIDE_EFFECTS (TREE_OPERAND (last, 1)) | |
584 | && current_function_has_nonlocal_label) | |
585 | make_goto_expr_edges (bb); | |
586 | ||
587 | make_eh_edges (last); | |
588 | make_edge (bb, bb->next_bb, EDGE_FALLTHRU); | |
589 | break; | |
590 | ||
591 | default: | |
592 | abort (); | |
593 | } | |
594 | } | |
595 | ||
596 | ||
597 | /* Create the edges for a COND_EXPR starting at block BB. | |
598 | At this point, both clauses must contain only simple gotos. */ | |
599 | ||
600 | static void | |
601 | make_cond_expr_edges (basic_block bb) | |
602 | { | |
603 | tree entry = last_stmt (bb); | |
604 | basic_block then_bb, else_bb; | |
605 | tree then_label, else_label; | |
606 | ||
607 | #if defined ENABLE_CHECKING | |
608 | if (entry == NULL_TREE || TREE_CODE (entry) != COND_EXPR) | |
609 | abort (); | |
610 | #endif | |
611 | ||
612 | /* Entry basic blocks for each component. */ | |
613 | then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry)); | |
614 | else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry)); | |
615 | then_bb = label_to_block (then_label); | |
616 | else_bb = label_to_block (else_label); | |
617 | ||
618 | make_edge (bb, then_bb, EDGE_TRUE_VALUE); | |
619 | make_edge (bb, else_bb, EDGE_FALSE_VALUE); | |
620 | } | |
621 | ||
622 | ||
623 | /* Create the edges for a SWITCH_EXPR starting at block BB. | |
624 | At this point, the switch body has been lowered and the | |
625 | SWITCH_LABELS filled in, so this is in effect a multi-way branch. */ | |
626 | ||
627 | static void | |
628 | make_switch_expr_edges (basic_block bb) | |
629 | { | |
630 | tree entry = last_stmt (bb); | |
631 | size_t i, n; | |
632 | tree vec; | |
633 | ||
634 | vec = SWITCH_LABELS (entry); | |
635 | n = TREE_VEC_LENGTH (vec); | |
636 | ||
637 | for (i = 0; i < n; ++i) | |
638 | { | |
639 | tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
640 | basic_block label_bb = label_to_block (lab); | |
641 | make_edge (bb, label_bb, 0); | |
642 | } | |
643 | } | |
644 | ||
645 | ||
646 | /* Return the basic block holding label DEST. */ | |
647 | ||
648 | basic_block | |
649 | label_to_block (tree dest) | |
650 | { | |
651 | return VARRAY_BB (label_to_block_map, LABEL_DECL_UID (dest)); | |
652 | } | |
653 | ||
654 | ||
655 | /* Create edges for a goto statement at block BB. */ | |
656 | ||
657 | static void | |
658 | make_goto_expr_edges (basic_block bb) | |
659 | { | |
660 | tree goto_t, dest; | |
661 | basic_block target_bb; | |
662 | int for_call; | |
663 | block_stmt_iterator last = bsi_last (bb); | |
664 | ||
665 | goto_t = bsi_stmt (last); | |
666 | ||
667 | /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR, | |
668 | CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting | |
669 | from a nonlocal goto. */ | |
670 | if (TREE_CODE (goto_t) != GOTO_EXPR) | |
671 | { | |
672 | dest = error_mark_node; | |
673 | for_call = 1; | |
674 | } | |
675 | else | |
676 | { | |
677 | dest = GOTO_DESTINATION (goto_t); | |
678 | for_call = 0; | |
679 | ||
680 | /* A GOTO to a local label creates normal edges. */ | |
681 | if (simple_goto_p (goto_t)) | |
682 | { | |
62b857ea RH |
683 | edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU); |
684 | e->goto_locus = EXPR_LOCUS (goto_t); | |
6de9cd9a DN |
685 | bsi_remove (&last); |
686 | return; | |
687 | } | |
688 | ||
9cf737f8 | 689 | /* Nothing more to do for nonlocal gotos. */ |
6de9cd9a DN |
690 | if (TREE_CODE (dest) == LABEL_DECL) |
691 | return; | |
692 | ||
693 | /* Computed gotos remain. */ | |
694 | } | |
695 | ||
696 | /* Look for the block starting with the destination label. In the | |
697 | case of a computed goto, make an edge to any label block we find | |
698 | in the CFG. */ | |
699 | FOR_EACH_BB (target_bb) | |
700 | { | |
701 | block_stmt_iterator bsi; | |
702 | ||
703 | for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
704 | { | |
705 | tree target = bsi_stmt (bsi); | |
706 | ||
707 | if (TREE_CODE (target) != LABEL_EXPR) | |
708 | break; | |
709 | ||
710 | if ( | |
711 | /* Computed GOTOs. Make an edge to every label block that has | |
712 | been marked as a potential target for a computed goto. */ | |
713 | (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0) | |
714 | /* Nonlocal GOTO target. Make an edge to every label block | |
715 | that has been marked as a potential target for a nonlocal | |
716 | goto. */ | |
717 | || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1)) | |
718 | { | |
719 | make_edge (bb, target_bb, EDGE_ABNORMAL); | |
720 | break; | |
721 | } | |
722 | } | |
723 | } | |
724 | ||
725 | /* Degenerate case of computed goto with no labels. */ | |
726 | if (!for_call && !bb->succ) | |
727 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
728 | } | |
729 | ||
730 | ||
731 | /*--------------------------------------------------------------------------- | |
732 | Flowgraph analysis | |
733 | ---------------------------------------------------------------------------*/ | |
734 | ||
735 | /* Remove unreachable blocks and other miscellaneous clean up work. */ | |
736 | ||
737 | void | |
738 | cleanup_tree_cfg (void) | |
739 | { | |
740 | bool something_changed = true; | |
741 | ||
742 | timevar_push (TV_TREE_CLEANUP_CFG); | |
743 | ||
744 | /* These three transformations can cascade, so we iterate on them until | |
745 | nothing changes. */ | |
746 | while (something_changed) | |
747 | { | |
748 | something_changed = cleanup_control_flow (); | |
749 | something_changed |= thread_jumps (); | |
750 | something_changed |= delete_unreachable_blocks (); | |
751 | } | |
752 | ||
753 | /* Merging the blocks creates no new opportunities for the other | |
754 | optimizations, so do it here. */ | |
755 | merge_seq_blocks (); | |
756 | ||
757 | compact_blocks (); | |
758 | ||
759 | #ifdef ENABLE_CHECKING | |
760 | verify_flow_info (); | |
761 | #endif | |
762 | timevar_pop (TV_TREE_CLEANUP_CFG); | |
763 | } | |
764 | ||
765 | ||
f698d217 SB |
766 | /* Cleanup useless labels in basic blocks. This is something we wish |
767 | to do early because it allows us to group case labels before creating | |
768 | the edges for the CFG, and it speeds up block statement iterators in | |
769 | all passes later on. | |
770 | We only run this pass once, running it more than once is probably not | |
771 | profitable. */ | |
772 | ||
773 | /* A map from basic block index to the leading label of that block. */ | |
774 | static tree *label_for_bb; | |
775 | ||
776 | /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */ | |
777 | static void | |
778 | update_eh_label (struct eh_region *region) | |
779 | { | |
780 | tree old_label = get_eh_region_tree_label (region); | |
781 | if (old_label) | |
782 | { | |
783 | tree new_label = label_for_bb[label_to_block (old_label)->index]; | |
784 | set_eh_region_tree_label (region, new_label); | |
785 | } | |
786 | } | |
787 | ||
788 | /* Cleanup redundant labels. This is a three-steo process: | |
789 | 1) Find the leading label for each block. | |
790 | 2) Redirect all references to labels to the leading labels. | |
791 | 3) Cleanup all useless labels. */ | |
6de9cd9a DN |
792 | |
793 | static void | |
794 | cleanup_dead_labels (void) | |
795 | { | |
796 | basic_block bb; | |
f698d217 | 797 | label_for_bb = xcalloc (last_basic_block, sizeof (tree)); |
6de9cd9a DN |
798 | |
799 | /* Find a suitable label for each block. We use the first user-defined | |
800 | label is there is one, or otherwise just the first label we see. */ | |
801 | FOR_EACH_BB (bb) | |
802 | { | |
803 | block_stmt_iterator i; | |
804 | ||
805 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
806 | { | |
807 | tree label, stmt = bsi_stmt (i); | |
808 | ||
809 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
810 | break; | |
811 | ||
812 | label = LABEL_EXPR_LABEL (stmt); | |
813 | ||
814 | /* If we have not yet seen a label for the current block, | |
815 | remember this one and see if there are more labels. */ | |
816 | if (! label_for_bb[bb->index]) | |
817 | { | |
818 | label_for_bb[bb->index] = label; | |
819 | continue; | |
820 | } | |
821 | ||
822 | /* If we did see a label for the current block already, but it | |
823 | is an artificially created label, replace it if the current | |
824 | label is a user defined label. */ | |
825 | if (! DECL_ARTIFICIAL (label) | |
826 | && DECL_ARTIFICIAL (label_for_bb[bb->index])) | |
827 | { | |
828 | label_for_bb[bb->index] = label; | |
829 | break; | |
830 | } | |
831 | } | |
832 | } | |
833 | ||
f698d217 SB |
834 | /* Now redirect all jumps/branches to the selected label. |
835 | First do so for each block ending in a control statement. */ | |
6de9cd9a DN |
836 | FOR_EACH_BB (bb) |
837 | { | |
838 | tree stmt = last_stmt (bb); | |
839 | if (!stmt) | |
840 | continue; | |
841 | ||
842 | switch (TREE_CODE (stmt)) | |
843 | { | |
844 | case COND_EXPR: | |
845 | { | |
846 | tree true_branch, false_branch; | |
847 | basic_block true_bb, false_bb; | |
848 | ||
849 | true_branch = COND_EXPR_THEN (stmt); | |
850 | false_branch = COND_EXPR_ELSE (stmt); | |
851 | true_bb = label_to_block (GOTO_DESTINATION (true_branch)); | |
852 | false_bb = label_to_block (GOTO_DESTINATION (false_branch)); | |
853 | ||
854 | GOTO_DESTINATION (true_branch) = label_for_bb[true_bb->index]; | |
855 | GOTO_DESTINATION (false_branch) = label_for_bb[false_bb->index]; | |
856 | ||
857 | break; | |
858 | } | |
859 | ||
860 | case SWITCH_EXPR: | |
861 | { | |
862 | size_t i; | |
863 | tree vec = SWITCH_LABELS (stmt); | |
864 | size_t n = TREE_VEC_LENGTH (vec); | |
865 | ||
866 | /* Replace all destination labels. */ | |
867 | for (i = 0; i < n; ++i) | |
868 | { | |
869 | tree label = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
870 | ||
871 | CASE_LABEL (TREE_VEC_ELT (vec, i)) = | |
872 | label_for_bb[label_to_block (label)->index]; | |
873 | } | |
874 | ||
875 | break; | |
876 | } | |
877 | ||
f667741c SB |
878 | /* We have to handle GOTO_EXPRs until they're removed, and we don't |
879 | remove them until after we've created the CFG edges. */ | |
880 | case GOTO_EXPR: | |
881 | { | |
882 | tree label = GOTO_DESTINATION (stmt); | |
883 | if (! computed_goto_p (stmt)) | |
884 | GOTO_DESTINATION (stmt) = | |
885 | label_for_bb[label_to_block (label)->index]; | |
886 | break; | |
887 | } | |
888 | ||
6de9cd9a DN |
889 | default: |
890 | break; | |
891 | } | |
892 | } | |
893 | ||
f698d217 SB |
894 | for_each_eh_region (update_eh_label); |
895 | ||
6de9cd9a DN |
896 | /* Finally, purge dead labels. All user-defined labels and labels that |
897 | can be the target of non-local gotos are preserved. */ | |
898 | FOR_EACH_BB (bb) | |
899 | { | |
900 | block_stmt_iterator i; | |
901 | tree label_for_this_bb = label_for_bb[bb->index]; | |
902 | ||
903 | if (! label_for_this_bb) | |
904 | continue; | |
905 | ||
906 | for (i = bsi_start (bb); !bsi_end_p (i); ) | |
907 | { | |
908 | tree label, stmt = bsi_stmt (i); | |
909 | ||
910 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
911 | break; | |
912 | ||
913 | label = LABEL_EXPR_LABEL (stmt); | |
914 | ||
915 | if (label == label_for_this_bb | |
916 | || ! DECL_ARTIFICIAL (label) | |
917 | || DECL_NONLOCAL (label)) | |
918 | bsi_next (&i); | |
919 | else | |
920 | bsi_remove (&i); | |
921 | } | |
922 | } | |
923 | ||
924 | free (label_for_bb); | |
925 | } | |
926 | ||
f667741c SB |
927 | /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE), |
928 | and scan the sorted vector of cases. Combine the ones jumping to the | |
929 | same label. | |
930 | Eg. three separate entries 1: 2: 3: become one entry 1..3: */ | |
931 | ||
932 | static void | |
933 | group_case_labels (void) | |
934 | { | |
935 | basic_block bb; | |
936 | ||
937 | FOR_EACH_BB (bb) | |
938 | { | |
939 | tree stmt = last_stmt (bb); | |
940 | if (stmt && TREE_CODE (stmt) == SWITCH_EXPR) | |
941 | { | |
942 | tree labels = SWITCH_LABELS (stmt); | |
943 | int old_size = TREE_VEC_LENGTH (labels); | |
944 | int i, j, new_size = old_size; | |
945 | ||
946 | /* Look for possible opportunities to merge cases. | |
947 | Ignore the last element of the label vector because it | |
948 | must be the default case. */ | |
949 | i = 0; | |
950 | while (i < old_size - 2) | |
951 | { | |
952 | tree base_case, base_label, base_high, type; | |
953 | base_case = TREE_VEC_ELT (labels, i); | |
954 | ||
955 | if (! base_case) | |
956 | abort (); | |
957 | ||
958 | type = TREE_TYPE (CASE_LOW (base_case)); | |
959 | base_label = CASE_LABEL (base_case); | |
960 | base_high = CASE_HIGH (base_case) ? | |
961 | CASE_HIGH (base_case) : CASE_LOW (base_case); | |
962 | ||
963 | /* Try to merge case labels. Break out when we reach the end | |
964 | of the label vector or when we cannot merge the next case | |
965 | label with the current one. */ | |
966 | while (i < old_size - 2) | |
967 | { | |
968 | tree merge_case = TREE_VEC_ELT (labels, ++i); | |
969 | tree merge_label = CASE_LABEL (merge_case); | |
970 | tree t = int_const_binop (PLUS_EXPR, base_high, | |
971 | integer_one_node, 1); | |
972 | ||
973 | /* Merge the cases if they jump to the same place, | |
974 | and their ranges are consecutive. */ | |
975 | if (merge_label == base_label | |
976 | && tree_int_cst_equal (CASE_LOW (merge_case), t)) | |
977 | { | |
978 | base_high = CASE_HIGH (merge_case) ? | |
979 | CASE_HIGH (merge_case) : CASE_LOW (merge_case); | |
980 | CASE_HIGH (base_case) = base_high; | |
981 | TREE_VEC_ELT (labels, i) = NULL_TREE; | |
982 | new_size--; | |
983 | } | |
984 | else | |
985 | break; | |
986 | } | |
987 | } | |
988 | ||
989 | /* Compress the case labels in the label vector, and adjust the | |
990 | length of the vector. */ | |
991 | for (i = 0, j = 0; i < new_size; i++) | |
992 | { | |
993 | while (! TREE_VEC_ELT (labels, j)) | |
994 | j++; | |
995 | TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++); | |
996 | } | |
997 | TREE_VEC_LENGTH (labels) = new_size; | |
998 | } | |
999 | } | |
1000 | } | |
6de9cd9a DN |
1001 | |
1002 | /* Checks whether we can merge block B into block A. */ | |
1003 | ||
1004 | static bool | |
1005 | tree_can_merge_blocks_p (basic_block a, basic_block b) | |
1006 | { | |
1007 | tree stmt; | |
1008 | block_stmt_iterator bsi; | |
1009 | ||
1010 | if (!a->succ | |
1011 | || a->succ->succ_next) | |
1012 | return false; | |
1013 | ||
1014 | if (a->succ->flags & EDGE_ABNORMAL) | |
1015 | return false; | |
1016 | ||
1017 | if (a->succ->dest != b) | |
1018 | return false; | |
1019 | ||
1020 | if (b == EXIT_BLOCK_PTR) | |
1021 | return false; | |
1022 | ||
1023 | if (b->pred->pred_next) | |
1024 | return false; | |
1025 | ||
1026 | /* If A ends by a statement causing exceptions or something similar, we | |
1027 | cannot merge the blocks. */ | |
1028 | stmt = last_stmt (a); | |
1029 | if (stmt && stmt_ends_bb_p (stmt)) | |
1030 | return false; | |
1031 | ||
1032 | /* Do not allow a block with only a non-local label to be merged. */ | |
1033 | if (stmt && TREE_CODE (stmt) == LABEL_EXPR | |
1034 | && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) | |
1035 | return false; | |
1036 | ||
1037 | /* There may be no phi nodes at the start of b. Most of these degenerate | |
1038 | phi nodes should be cleaned up by kill_redundant_phi_nodes. */ | |
1039 | if (phi_nodes (b)) | |
1040 | return false; | |
1041 | ||
1042 | /* Do not remove user labels. */ | |
1043 | for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi)) | |
1044 | { | |
1045 | stmt = bsi_stmt (bsi); | |
1046 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
1047 | break; | |
1048 | if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt))) | |
1049 | return false; | |
1050 | } | |
1051 | ||
1052 | return true; | |
1053 | } | |
1054 | ||
1055 | ||
1056 | /* Merge block B into block A. */ | |
1057 | ||
1058 | static void | |
1059 | tree_merge_blocks (basic_block a, basic_block b) | |
1060 | { | |
1061 | block_stmt_iterator bsi; | |
1062 | tree_stmt_iterator last; | |
1063 | ||
1064 | if (dump_file) | |
1065 | fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index); | |
1066 | ||
1067 | /* Ensure that B follows A. */ | |
1068 | move_block_after (b, a); | |
1069 | ||
1070 | if (!(a->succ->flags & EDGE_FALLTHRU)) | |
1071 | abort (); | |
1072 | ||
1073 | if (last_stmt (a) | |
1074 | && stmt_ends_bb_p (last_stmt (a))) | |
1075 | abort (); | |
1076 | ||
1077 | /* Remove labels from B and set bb_for_stmt to A for other statements. */ | |
1078 | for (bsi = bsi_start (b); !bsi_end_p (bsi);) | |
1079 | { | |
1080 | if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR) | |
1081 | bsi_remove (&bsi); | |
1082 | else | |
1083 | { | |
1084 | set_bb_for_stmt (bsi_stmt (bsi), a); | |
1085 | bsi_next (&bsi); | |
1086 | } | |
1087 | } | |
1088 | ||
1089 | /* Merge the chains. */ | |
1090 | last = tsi_last (a->stmt_list); | |
1091 | tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT); | |
1092 | b->stmt_list = NULL; | |
1093 | } | |
1094 | ||
1095 | ||
1096 | /* Walk the function tree removing unnecessary statements. | |
1097 | ||
1098 | * Empty statement nodes are removed | |
1099 | ||
1100 | * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed | |
1101 | ||
1102 | * Unnecessary COND_EXPRs are removed | |
1103 | ||
1104 | * Some unnecessary BIND_EXPRs are removed | |
1105 | ||
1106 | Clearly more work could be done. The trick is doing the analysis | |
1107 | and removal fast enough to be a net improvement in compile times. | |
1108 | ||
1109 | Note that when we remove a control structure such as a COND_EXPR | |
1110 | BIND_EXPR, or TRY block, we will need to repeat this optimization pass | |
1111 | to ensure we eliminate all the useless code. */ | |
1112 | ||
1113 | struct rus_data | |
1114 | { | |
1115 | tree *last_goto; | |
1116 | bool repeat; | |
1117 | bool may_throw; | |
1118 | bool may_branch; | |
1119 | bool has_label; | |
1120 | }; | |
1121 | ||
1122 | static void remove_useless_stmts_1 (tree *, struct rus_data *); | |
1123 | ||
1124 | static bool | |
1125 | remove_useless_stmts_warn_notreached (tree stmt) | |
1126 | { | |
1127 | if (EXPR_LOCUS (stmt)) | |
1128 | { | |
1129 | warning ("%Hwill never be executed", EXPR_LOCUS (stmt)); | |
1130 | return true; | |
1131 | } | |
1132 | ||
1133 | switch (TREE_CODE (stmt)) | |
1134 | { | |
1135 | case STATEMENT_LIST: | |
1136 | { | |
1137 | tree_stmt_iterator i; | |
1138 | for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i)) | |
1139 | if (remove_useless_stmts_warn_notreached (tsi_stmt (i))) | |
1140 | return true; | |
1141 | } | |
1142 | break; | |
1143 | ||
1144 | case COND_EXPR: | |
1145 | if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt))) | |
1146 | return true; | |
1147 | if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt))) | |
1148 | return true; | |
1149 | if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt))) | |
1150 | return true; | |
1151 | break; | |
1152 | ||
1153 | case TRY_FINALLY_EXPR: | |
1154 | case TRY_CATCH_EXPR: | |
1155 | if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0))) | |
1156 | return true; | |
1157 | if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1))) | |
1158 | return true; | |
1159 | break; | |
1160 | ||
1161 | case CATCH_EXPR: | |
1162 | return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt)); | |
1163 | case EH_FILTER_EXPR: | |
1164 | return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt)); | |
1165 | case BIND_EXPR: | |
1166 | return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt)); | |
1167 | ||
1168 | default: | |
1169 | /* Not a live container. */ | |
1170 | break; | |
1171 | } | |
1172 | ||
1173 | return false; | |
1174 | } | |
1175 | ||
1176 | static void | |
1177 | remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data) | |
1178 | { | |
1179 | tree then_clause, else_clause, cond; | |
1180 | bool save_has_label, then_has_label, else_has_label; | |
1181 | ||
1182 | save_has_label = data->has_label; | |
1183 | data->has_label = false; | |
1184 | data->last_goto = NULL; | |
1185 | ||
1186 | remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data); | |
1187 | ||
1188 | then_has_label = data->has_label; | |
1189 | data->has_label = false; | |
1190 | data->last_goto = NULL; | |
1191 | ||
1192 | remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data); | |
1193 | ||
1194 | else_has_label = data->has_label; | |
1195 | data->has_label = save_has_label | then_has_label | else_has_label; | |
1196 | ||
1197 | fold_stmt (stmt_p); | |
1198 | then_clause = COND_EXPR_THEN (*stmt_p); | |
1199 | else_clause = COND_EXPR_ELSE (*stmt_p); | |
1200 | cond = COND_EXPR_COND (*stmt_p); | |
1201 | ||
1202 | /* If neither arm does anything at all, we can remove the whole IF. */ | |
1203 | if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause)) | |
1204 | { | |
1205 | *stmt_p = build_empty_stmt (); | |
1206 | data->repeat = true; | |
1207 | } | |
1208 | ||
1209 | /* If there are no reachable statements in an arm, then we can | |
1210 | zap the entire conditional. */ | |
1211 | else if (integer_nonzerop (cond) && !else_has_label) | |
1212 | { | |
1213 | if (warn_notreached) | |
1214 | remove_useless_stmts_warn_notreached (else_clause); | |
1215 | *stmt_p = then_clause; | |
1216 | data->repeat = true; | |
1217 | } | |
1218 | else if (integer_zerop (cond) && !then_has_label) | |
1219 | { | |
1220 | if (warn_notreached) | |
1221 | remove_useless_stmts_warn_notreached (then_clause); | |
1222 | *stmt_p = else_clause; | |
1223 | data->repeat = true; | |
1224 | } | |
1225 | ||
1226 | /* Check a couple of simple things on then/else with single stmts. */ | |
1227 | else | |
1228 | { | |
1229 | tree then_stmt = expr_only (then_clause); | |
1230 | tree else_stmt = expr_only (else_clause); | |
1231 | ||
1232 | /* Notice branches to a common destination. */ | |
1233 | if (then_stmt && else_stmt | |
1234 | && TREE_CODE (then_stmt) == GOTO_EXPR | |
1235 | && TREE_CODE (else_stmt) == GOTO_EXPR | |
1236 | && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt))) | |
1237 | { | |
1238 | *stmt_p = then_stmt; | |
1239 | data->repeat = true; | |
1240 | } | |
1241 | ||
1242 | /* If the THEN/ELSE clause merely assigns a value to a variable or | |
1243 | parameter which is already known to contain that value, then | |
1244 | remove the useless THEN/ELSE clause. */ | |
1245 | else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL) | |
1246 | { | |
1247 | if (else_stmt | |
1248 | && TREE_CODE (else_stmt) == MODIFY_EXPR | |
1249 | && TREE_OPERAND (else_stmt, 0) == cond | |
1250 | && integer_zerop (TREE_OPERAND (else_stmt, 1))) | |
1251 | COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list (); | |
1252 | } | |
1253 | else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) | |
1254 | && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL | |
1255 | || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL) | |
1256 | && TREE_CONSTANT (TREE_OPERAND (cond, 1))) | |
1257 | { | |
1258 | tree stmt = (TREE_CODE (cond) == EQ_EXPR | |
1259 | ? then_stmt : else_stmt); | |
1260 | tree *location = (TREE_CODE (cond) == EQ_EXPR | |
1261 | ? &COND_EXPR_THEN (*stmt_p) | |
1262 | : &COND_EXPR_ELSE (*stmt_p)); | |
1263 | ||
1264 | if (stmt | |
1265 | && TREE_CODE (stmt) == MODIFY_EXPR | |
1266 | && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0) | |
1267 | && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1)) | |
1268 | *location = alloc_stmt_list (); | |
1269 | } | |
1270 | } | |
1271 | ||
1272 | /* Protect GOTOs in the arm of COND_EXPRs from being removed. They | |
1273 | would be re-introduced during lowering. */ | |
1274 | data->last_goto = NULL; | |
1275 | } | |
1276 | ||
1277 | ||
1278 | static void | |
1279 | remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data) | |
1280 | { | |
1281 | bool save_may_branch, save_may_throw; | |
1282 | bool this_may_branch, this_may_throw; | |
1283 | ||
1284 | /* Collect may_branch and may_throw information for the body only. */ | |
1285 | save_may_branch = data->may_branch; | |
1286 | save_may_throw = data->may_throw; | |
1287 | data->may_branch = false; | |
1288 | data->may_throw = false; | |
1289 | data->last_goto = NULL; | |
1290 | ||
1291 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); | |
1292 | ||
1293 | this_may_branch = data->may_branch; | |
1294 | this_may_throw = data->may_throw; | |
1295 | data->may_branch |= save_may_branch; | |
1296 | data->may_throw |= save_may_throw; | |
1297 | data->last_goto = NULL; | |
1298 | ||
1299 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); | |
1300 | ||
1301 | /* If the body is empty, then we can emit the FINALLY block without | |
1302 | the enclosing TRY_FINALLY_EXPR. */ | |
1303 | if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0))) | |
1304 | { | |
1305 | *stmt_p = TREE_OPERAND (*stmt_p, 1); | |
1306 | data->repeat = true; | |
1307 | } | |
1308 | ||
1309 | /* If the handler is empty, then we can emit the TRY block without | |
1310 | the enclosing TRY_FINALLY_EXPR. */ | |
1311 | else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) | |
1312 | { | |
1313 | *stmt_p = TREE_OPERAND (*stmt_p, 0); | |
1314 | data->repeat = true; | |
1315 | } | |
1316 | ||
1317 | /* If the body neither throws, nor branches, then we can safely | |
1318 | string the TRY and FINALLY blocks together. */ | |
1319 | else if (!this_may_branch && !this_may_throw) | |
1320 | { | |
1321 | tree stmt = *stmt_p; | |
1322 | *stmt_p = TREE_OPERAND (stmt, 0); | |
1323 | append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p); | |
1324 | data->repeat = true; | |
1325 | } | |
1326 | } | |
1327 | ||
1328 | ||
1329 | static void | |
1330 | remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data) | |
1331 | { | |
1332 | bool save_may_throw, this_may_throw; | |
1333 | tree_stmt_iterator i; | |
1334 | tree stmt; | |
1335 | ||
1336 | /* Collect may_throw information for the body only. */ | |
1337 | save_may_throw = data->may_throw; | |
1338 | data->may_throw = false; | |
1339 | data->last_goto = NULL; | |
1340 | ||
1341 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data); | |
1342 | ||
1343 | this_may_throw = data->may_throw; | |
1344 | data->may_throw = save_may_throw; | |
1345 | ||
1346 | /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */ | |
1347 | if (!this_may_throw) | |
1348 | { | |
1349 | if (warn_notreached) | |
1350 | remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1)); | |
1351 | *stmt_p = TREE_OPERAND (*stmt_p, 0); | |
1352 | data->repeat = true; | |
1353 | return; | |
1354 | } | |
1355 | ||
1356 | /* Process the catch clause specially. We may be able to tell that | |
1357 | no exceptions propagate past this point. */ | |
1358 | ||
1359 | this_may_throw = true; | |
1360 | i = tsi_start (TREE_OPERAND (*stmt_p, 1)); | |
1361 | stmt = tsi_stmt (i); | |
1362 | data->last_goto = NULL; | |
1363 | ||
1364 | switch (TREE_CODE (stmt)) | |
1365 | { | |
1366 | case CATCH_EXPR: | |
1367 | for (; !tsi_end_p (i); tsi_next (&i)) | |
1368 | { | |
1369 | stmt = tsi_stmt (i); | |
1370 | /* If we catch all exceptions, then the body does not | |
1371 | propagate exceptions past this point. */ | |
1372 | if (CATCH_TYPES (stmt) == NULL) | |
1373 | this_may_throw = false; | |
1374 | data->last_goto = NULL; | |
1375 | remove_useless_stmts_1 (&CATCH_BODY (stmt), data); | |
1376 | } | |
1377 | break; | |
1378 | ||
1379 | case EH_FILTER_EXPR: | |
1380 | if (EH_FILTER_MUST_NOT_THROW (stmt)) | |
1381 | this_may_throw = false; | |
1382 | else if (EH_FILTER_TYPES (stmt) == NULL) | |
1383 | this_may_throw = false; | |
1384 | remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data); | |
1385 | break; | |
1386 | ||
1387 | default: | |
1388 | /* Otherwise this is a cleanup. */ | |
1389 | remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data); | |
1390 | ||
1391 | /* If the cleanup is empty, then we can emit the TRY block without | |
1392 | the enclosing TRY_CATCH_EXPR. */ | |
1393 | if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1))) | |
1394 | { | |
1395 | *stmt_p = TREE_OPERAND (*stmt_p, 0); | |
1396 | data->repeat = true; | |
1397 | } | |
1398 | break; | |
1399 | } | |
1400 | data->may_throw |= this_may_throw; | |
1401 | } | |
1402 | ||
1403 | ||
1404 | static void | |
1405 | remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data) | |
1406 | { | |
1407 | tree block; | |
1408 | ||
1409 | /* First remove anything underneath the BIND_EXPR. */ | |
1410 | remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data); | |
1411 | ||
1412 | /* If the BIND_EXPR has no variables, then we can pull everything | |
1413 | up one level and remove the BIND_EXPR, unless this is the toplevel | |
1414 | BIND_EXPR for the current function or an inlined function. | |
1415 | ||
1416 | When this situation occurs we will want to apply this | |
1417 | optimization again. */ | |
1418 | block = BIND_EXPR_BLOCK (*stmt_p); | |
1419 | if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE | |
1420 | && *stmt_p != DECL_SAVED_TREE (current_function_decl) | |
1421 | && (! block | |
1422 | || ! BLOCK_ABSTRACT_ORIGIN (block) | |
1423 | || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block)) | |
1424 | != FUNCTION_DECL))) | |
1425 | { | |
1426 | *stmt_p = BIND_EXPR_BODY (*stmt_p); | |
1427 | data->repeat = true; | |
1428 | } | |
1429 | } | |
1430 | ||
1431 | ||
1432 | static void | |
1433 | remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data) | |
1434 | { | |
1435 | tree dest = GOTO_DESTINATION (*stmt_p); | |
1436 | ||
1437 | data->may_branch = true; | |
1438 | data->last_goto = NULL; | |
1439 | ||
1440 | /* Record the last goto expr, so that we can delete it if unnecessary. */ | |
1441 | if (TREE_CODE (dest) == LABEL_DECL) | |
1442 | data->last_goto = stmt_p; | |
1443 | } | |
1444 | ||
1445 | ||
1446 | static void | |
1447 | remove_useless_stmts_label (tree *stmt_p, struct rus_data *data) | |
1448 | { | |
1449 | tree label = LABEL_EXPR_LABEL (*stmt_p); | |
1450 | ||
1451 | data->has_label = true; | |
1452 | ||
1453 | /* We do want to jump across non-local label receiver code. */ | |
1454 | if (DECL_NONLOCAL (label)) | |
1455 | data->last_goto = NULL; | |
1456 | ||
1457 | else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label) | |
1458 | { | |
1459 | *data->last_goto = build_empty_stmt (); | |
1460 | data->repeat = true; | |
1461 | } | |
1462 | ||
1463 | /* ??? Add something here to delete unused labels. */ | |
1464 | } | |
1465 | ||
1466 | ||
1467 | /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its | |
1468 | decl. This allows us to eliminate redundant or useless | |
1469 | calls to "const" functions. | |
1470 | ||
1471 | Gimplifier already does the same operation, but we may notice functions | |
1472 | being const and pure once their calls has been gimplified, so we need | |
1473 | to update the flag. */ | |
1474 | ||
1475 | static void | |
1476 | update_call_expr_flags (tree call) | |
1477 | { | |
1478 | tree decl = get_callee_fndecl (call); | |
1479 | if (!decl) | |
1480 | return; | |
1481 | if (call_expr_flags (call) & (ECF_CONST | ECF_PURE)) | |
1482 | TREE_SIDE_EFFECTS (call) = 0; | |
1483 | if (TREE_NOTHROW (decl)) | |
1484 | TREE_NOTHROW (call) = 1; | |
1485 | } | |
1486 | ||
1487 | ||
1488 | /* T is CALL_EXPR. Set current_function_calls_* flags. */ | |
1489 | ||
1490 | void | |
1491 | notice_special_calls (tree t) | |
1492 | { | |
1493 | int flags = call_expr_flags (t); | |
1494 | ||
1495 | if (flags & ECF_MAY_BE_ALLOCA) | |
1496 | current_function_calls_alloca = true; | |
1497 | if (flags & ECF_RETURNS_TWICE) | |
1498 | current_function_calls_setjmp = true; | |
1499 | } | |
1500 | ||
1501 | ||
1502 | /* Clear flags set by notice_special_calls. Used by dead code removal | |
1503 | to update the flags. */ | |
1504 | ||
1505 | void | |
1506 | clear_special_calls (void) | |
1507 | { | |
1508 | current_function_calls_alloca = false; | |
1509 | current_function_calls_setjmp = false; | |
1510 | } | |
1511 | ||
1512 | ||
1513 | static void | |
1514 | remove_useless_stmts_1 (tree *tp, struct rus_data *data) | |
1515 | { | |
1516 | tree t = *tp; | |
1517 | ||
1518 | switch (TREE_CODE (t)) | |
1519 | { | |
1520 | case COND_EXPR: | |
1521 | remove_useless_stmts_cond (tp, data); | |
1522 | break; | |
1523 | ||
1524 | case TRY_FINALLY_EXPR: | |
1525 | remove_useless_stmts_tf (tp, data); | |
1526 | break; | |
1527 | ||
1528 | case TRY_CATCH_EXPR: | |
1529 | remove_useless_stmts_tc (tp, data); | |
1530 | break; | |
1531 | ||
1532 | case BIND_EXPR: | |
1533 | remove_useless_stmts_bind (tp, data); | |
1534 | break; | |
1535 | ||
1536 | case GOTO_EXPR: | |
1537 | remove_useless_stmts_goto (tp, data); | |
1538 | break; | |
1539 | ||
1540 | case LABEL_EXPR: | |
1541 | remove_useless_stmts_label (tp, data); | |
1542 | break; | |
1543 | ||
1544 | case RETURN_EXPR: | |
1545 | fold_stmt (tp); | |
1546 | data->last_goto = NULL; | |
1547 | data->may_branch = true; | |
1548 | break; | |
1549 | ||
1550 | case CALL_EXPR: | |
1551 | fold_stmt (tp); | |
1552 | data->last_goto = NULL; | |
1553 | notice_special_calls (t); | |
1554 | update_call_expr_flags (t); | |
1555 | if (tree_could_throw_p (t)) | |
1556 | data->may_throw = true; | |
1557 | break; | |
1558 | ||
1559 | case MODIFY_EXPR: | |
1560 | data->last_goto = NULL; | |
1561 | fold_stmt (tp); | |
1562 | if (TREE_CODE (TREE_OPERAND (t, 1)) == CALL_EXPR) | |
1563 | { | |
1564 | update_call_expr_flags (TREE_OPERAND (t, 1)); | |
1565 | notice_special_calls (TREE_OPERAND (t, 1)); | |
1566 | } | |
1567 | if (tree_could_throw_p (t)) | |
1568 | data->may_throw = true; | |
1569 | break; | |
1570 | ||
1571 | case STATEMENT_LIST: | |
1572 | { | |
1573 | tree_stmt_iterator i = tsi_start (t); | |
1574 | while (!tsi_end_p (i)) | |
1575 | { | |
1576 | t = tsi_stmt (i); | |
1577 | if (IS_EMPTY_STMT (t)) | |
1578 | { | |
1579 | tsi_delink (&i); | |
1580 | continue; | |
1581 | } | |
1582 | ||
1583 | remove_useless_stmts_1 (tsi_stmt_ptr (i), data); | |
1584 | ||
1585 | t = tsi_stmt (i); | |
1586 | if (TREE_CODE (t) == STATEMENT_LIST) | |
1587 | { | |
1588 | tsi_link_before (&i, t, TSI_SAME_STMT); | |
1589 | tsi_delink (&i); | |
1590 | } | |
1591 | else | |
1592 | tsi_next (&i); | |
1593 | } | |
1594 | } | |
1595 | break; | |
1596 | case SWITCH_EXPR: | |
1597 | fold_stmt (tp); | |
1598 | data->last_goto = NULL; | |
1599 | break; | |
1600 | ||
1601 | default: | |
1602 | data->last_goto = NULL; | |
1603 | break; | |
1604 | } | |
1605 | } | |
1606 | ||
1607 | static void | |
1608 | remove_useless_stmts (void) | |
1609 | { | |
1610 | struct rus_data data; | |
1611 | ||
1612 | clear_special_calls (); | |
1613 | ||
1614 | do | |
1615 | { | |
1616 | memset (&data, 0, sizeof (data)); | |
1617 | remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data); | |
1618 | } | |
1619 | while (data.repeat); | |
1620 | } | |
1621 | ||
1622 | ||
1623 | struct tree_opt_pass pass_remove_useless_stmts = | |
1624 | { | |
1625 | "useless", /* name */ | |
1626 | NULL, /* gate */ | |
1627 | remove_useless_stmts, /* execute */ | |
1628 | NULL, /* sub */ | |
1629 | NULL, /* next */ | |
1630 | 0, /* static_pass_number */ | |
1631 | 0, /* tv_id */ | |
1632 | PROP_gimple_any, /* properties_required */ | |
1633 | 0, /* properties_provided */ | |
1634 | 0, /* properties_destroyed */ | |
1635 | 0, /* todo_flags_start */ | |
1636 | TODO_dump_func /* todo_flags_finish */ | |
1637 | }; | |
1638 | ||
1639 | ||
1640 | /* Remove obviously useless statements in basic block BB. */ | |
1641 | ||
1642 | static void | |
1643 | cfg_remove_useless_stmts_bb (basic_block bb) | |
1644 | { | |
1645 | block_stmt_iterator bsi; | |
1646 | tree stmt = NULL_TREE; | |
1647 | tree cond, var = NULL_TREE, val = NULL_TREE; | |
1648 | struct var_ann_d *ann; | |
1649 | ||
1650 | /* Check whether we come here from a condition, and if so, get the | |
1651 | condition. */ | |
1652 | if (!bb->pred | |
1653 | || bb->pred->pred_next | |
1654 | || !(bb->pred->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
1655 | return; | |
1656 | ||
1657 | cond = COND_EXPR_COND (last_stmt (bb->pred->src)); | |
1658 | ||
1659 | if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL) | |
1660 | { | |
1661 | var = cond; | |
1662 | val = (bb->pred->flags & EDGE_FALSE_VALUE | |
1663 | ? boolean_false_node : boolean_true_node); | |
1664 | } | |
1665 | else if (TREE_CODE (cond) == TRUTH_NOT_EXPR | |
1666 | && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL | |
1667 | || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)) | |
1668 | { | |
1669 | var = TREE_OPERAND (cond, 0); | |
1670 | val = (bb->pred->flags & EDGE_FALSE_VALUE | |
1671 | ? boolean_true_node : boolean_false_node); | |
1672 | } | |
1673 | else | |
1674 | { | |
1675 | if (bb->pred->flags & EDGE_FALSE_VALUE) | |
1676 | cond = invert_truthvalue (cond); | |
1677 | if (TREE_CODE (cond) == EQ_EXPR | |
1678 | && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL | |
1679 | || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL) | |
1680 | && (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL | |
1681 | || TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL | |
1682 | || TREE_CONSTANT (TREE_OPERAND (cond, 1)))) | |
1683 | { | |
1684 | var = TREE_OPERAND (cond, 0); | |
1685 | val = TREE_OPERAND (cond, 1); | |
1686 | } | |
1687 | else | |
1688 | return; | |
1689 | } | |
1690 | ||
1691 | /* Only work for normal local variables. */ | |
1692 | ann = var_ann (var); | |
1693 | if (!ann | |
1694 | || ann->may_aliases | |
1695 | || TREE_ADDRESSABLE (var)) | |
1696 | return; | |
1697 | ||
1698 | if (! TREE_CONSTANT (val)) | |
1699 | { | |
1700 | ann = var_ann (val); | |
1701 | if (!ann | |
1702 | || ann->may_aliases | |
1703 | || TREE_ADDRESSABLE (val)) | |
1704 | return; | |
1705 | } | |
1706 | ||
1707 | /* Ignore floating point variables, since comparison behaves weird for | |
1708 | them. */ | |
1709 | if (FLOAT_TYPE_P (TREE_TYPE (var))) | |
1710 | return; | |
1711 | ||
1712 | for (bsi = bsi_start (bb); !bsi_end_p (bsi);) | |
1713 | { | |
1714 | stmt = bsi_stmt (bsi); | |
1715 | ||
1716 | /* If the THEN/ELSE clause merely assigns a value to a variable/parameter | |
1717 | which is already known to contain that value, then remove the useless | |
1718 | THEN/ELSE clause. */ | |
1719 | if (TREE_CODE (stmt) == MODIFY_EXPR | |
1720 | && TREE_OPERAND (stmt, 0) == var | |
1721 | && operand_equal_p (val, TREE_OPERAND (stmt, 1), 0)) | |
1722 | { | |
1723 | bsi_remove (&bsi); | |
1724 | continue; | |
1725 | } | |
1726 | ||
1727 | /* Invalidate the var if we encounter something that could modify it. */ | |
1728 | if (TREE_CODE (stmt) == ASM_EXPR | |
1729 | || TREE_CODE (stmt) == VA_ARG_EXPR | |
1730 | || (TREE_CODE (stmt) == MODIFY_EXPR | |
1731 | && (TREE_OPERAND (stmt, 0) == var | |
1732 | || TREE_OPERAND (stmt, 0) == val | |
1733 | || TREE_CODE (TREE_OPERAND (stmt, 1)) == VA_ARG_EXPR))) | |
1734 | return; | |
1735 | ||
1736 | bsi_next (&bsi); | |
1737 | } | |
1738 | } | |
1739 | ||
1740 | ||
1741 | /* A CFG-aware version of remove_useless_stmts. */ | |
1742 | ||
1743 | void | |
1744 | cfg_remove_useless_stmts (void) | |
1745 | { | |
1746 | basic_block bb; | |
1747 | ||
1748 | #ifdef ENABLE_CHECKING | |
1749 | verify_flow_info (); | |
1750 | #endif | |
1751 | ||
1752 | FOR_EACH_BB (bb) | |
1753 | { | |
1754 | cfg_remove_useless_stmts_bb (bb); | |
1755 | } | |
1756 | } | |
1757 | ||
1758 | ||
1759 | /* Remove PHI nodes associated with basic block BB and all edges out of BB. */ | |
1760 | ||
1761 | static void | |
1762 | remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb) | |
1763 | { | |
1764 | tree phi; | |
1765 | ||
1766 | /* Since this block is no longer reachable, we can just delete all | |
1767 | of its PHI nodes. */ | |
1768 | phi = phi_nodes (bb); | |
1769 | while (phi) | |
1770 | { | |
17192884 | 1771 | tree next = PHI_CHAIN (phi); |
6de9cd9a DN |
1772 | remove_phi_node (phi, NULL_TREE, bb); |
1773 | phi = next; | |
1774 | } | |
1775 | ||
1776 | /* Remove edges to BB's successors. */ | |
1777 | while (bb->succ != NULL) | |
1778 | ssa_remove_edge (bb->succ); | |
1779 | } | |
1780 | ||
1781 | ||
1782 | /* Remove statements of basic block BB. */ | |
1783 | ||
1784 | static void | |
1785 | remove_bb (basic_block bb) | |
1786 | { | |
1787 | block_stmt_iterator i; | |
1788 | location_t *loc = NULL; | |
1789 | ||
1790 | if (dump_file) | |
1791 | { | |
1792 | fprintf (dump_file, "Removing basic block %d\n", bb->index); | |
1793 | if (dump_flags & TDF_DETAILS) | |
1794 | { | |
1795 | dump_bb (bb, dump_file, 0); | |
1796 | fprintf (dump_file, "\n"); | |
1797 | } | |
1798 | } | |
1799 | ||
1800 | /* Remove all the instructions in the block. */ | |
1801 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_remove (&i)) | |
1802 | { | |
1803 | tree stmt = bsi_stmt (i); | |
1804 | ||
1805 | set_bb_for_stmt (stmt, NULL); | |
1806 | ||
1807 | /* Don't warn for removed gotos. Gotos are often removed due to | |
1808 | jump threading, thus resulting in bogus warnings. Not great, | |
1809 | since this way we lose warnings for gotos in the original | |
1810 | program that are indeed unreachable. */ | |
1811 | if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_LOCUS (stmt) && !loc) | |
1812 | loc = EXPR_LOCUS (stmt); | |
1813 | } | |
1814 | ||
1815 | /* If requested, give a warning that the first statement in the | |
1816 | block is unreachable. We walk statements backwards in the | |
1817 | loop above, so the last statement we process is the first statement | |
1818 | in the block. */ | |
1819 | if (warn_notreached && loc) | |
1820 | warning ("%Hwill never be executed", loc); | |
1821 | ||
1822 | remove_phi_nodes_and_edges_for_unreachable_block (bb); | |
1823 | } | |
1824 | ||
1825 | ||
1826 | /* Examine BB to determine if it is a forwarding block (a block which only | |
1827 | transfers control to a new destination). If BB is a forwarding block, | |
1828 | then return the edge leading to the ultimate destination. */ | |
1829 | ||
1830 | edge | |
1831 | tree_block_forwards_to (basic_block bb) | |
1832 | { | |
1833 | block_stmt_iterator bsi; | |
1834 | bb_ann_t ann = bb_ann (bb); | |
1835 | tree stmt; | |
1836 | ||
1837 | /* If this block is not forwardable, then avoid useless work. */ | |
1838 | if (! ann->forwardable) | |
1839 | return NULL; | |
1840 | ||
1841 | /* Set this block to not be forwardable. This prevents infinite loops since | |
1842 | any block currently under examination is considered non-forwardable. */ | |
1843 | ann->forwardable = 0; | |
1844 | ||
1845 | /* No forwarding is possible if this block is a special block (ENTRY/EXIT), | |
1846 | this block has more than one successor, this block's single successor is | |
1847 | reached via an abnormal edge, this block has phi nodes, or this block's | |
1848 | single successor has phi nodes. */ | |
1849 | if (bb == EXIT_BLOCK_PTR | |
1850 | || bb == ENTRY_BLOCK_PTR | |
1851 | || !bb->succ | |
1852 | || bb->succ->succ_next | |
1853 | || bb->succ->dest == EXIT_BLOCK_PTR | |
1854 | || (bb->succ->flags & EDGE_ABNORMAL) != 0 | |
1855 | || phi_nodes (bb) | |
1856 | || phi_nodes (bb->succ->dest)) | |
1857 | return NULL; | |
1858 | ||
1859 | /* Walk past any labels at the start of this block. */ | |
1860 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
1861 | { | |
1862 | stmt = bsi_stmt (bsi); | |
1863 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
1864 | break; | |
1865 | } | |
1866 | ||
1867 | /* If we reached the end of this block we may be able to optimize this | |
1868 | case. */ | |
1869 | if (bsi_end_p (bsi)) | |
1870 | { | |
1871 | edge dest; | |
1872 | ||
1873 | /* Recursive call to pick up chains of forwarding blocks. */ | |
1874 | dest = tree_block_forwards_to (bb->succ->dest); | |
1875 | ||
1876 | /* If none found, we forward to bb->succ at minimum. */ | |
1877 | if (!dest) | |
1878 | dest = bb->succ; | |
1879 | ||
1880 | ann->forwardable = 1; | |
1881 | return dest; | |
1882 | } | |
1883 | ||
1884 | /* No forwarding possible. */ | |
1885 | return NULL; | |
1886 | } | |
1887 | ||
1888 | ||
1889 | /* Try to remove superfluous control structures. */ | |
1890 | ||
1891 | static bool | |
1892 | cleanup_control_flow (void) | |
1893 | { | |
1894 | basic_block bb; | |
1895 | block_stmt_iterator bsi; | |
1896 | bool retval = false; | |
1897 | tree stmt; | |
1898 | ||
1899 | FOR_EACH_BB (bb) | |
1900 | { | |
1901 | bsi = bsi_last (bb); | |
1902 | ||
1903 | if (bsi_end_p (bsi)) | |
1904 | continue; | |
1905 | ||
1906 | stmt = bsi_stmt (bsi); | |
1907 | if (TREE_CODE (stmt) == COND_EXPR | |
1908 | || TREE_CODE (stmt) == SWITCH_EXPR) | |
1909 | retval |= cleanup_control_expr_graph (bb, bsi); | |
1910 | } | |
1911 | return retval; | |
1912 | } | |
1913 | ||
1914 | ||
1915 | /* Disconnect an unreachable block in the control expression starting | |
1916 | at block BB. */ | |
1917 | ||
1918 | static bool | |
1919 | cleanup_control_expr_graph (basic_block bb, block_stmt_iterator bsi) | |
1920 | { | |
1921 | edge taken_edge; | |
1922 | bool retval = false; | |
1923 | tree expr = bsi_stmt (bsi), val; | |
1924 | ||
1925 | if (bb->succ->succ_next) | |
1926 | { | |
1927 | edge e, next; | |
1928 | ||
1929 | switch (TREE_CODE (expr)) | |
1930 | { | |
1931 | case COND_EXPR: | |
1932 | val = COND_EXPR_COND (expr); | |
1933 | break; | |
1934 | ||
1935 | case SWITCH_EXPR: | |
1936 | val = SWITCH_COND (expr); | |
1937 | if (TREE_CODE (val) != INTEGER_CST) | |
1938 | return false; | |
1939 | break; | |
1940 | ||
1941 | default: | |
1942 | abort (); | |
1943 | } | |
1944 | ||
1945 | taken_edge = find_taken_edge (bb, val); | |
1946 | if (!taken_edge) | |
1947 | return false; | |
1948 | ||
1949 | /* Remove all the edges except the one that is always executed. */ | |
1950 | for (e = bb->succ; e; e = next) | |
1951 | { | |
1952 | next = e->succ_next; | |
1953 | if (e != taken_edge) | |
1954 | { | |
1955 | taken_edge->probability += e->probability; | |
1956 | taken_edge->count += e->count; | |
1957 | ssa_remove_edge (e); | |
1958 | retval = true; | |
1959 | } | |
1960 | } | |
1961 | if (taken_edge->probability > REG_BR_PROB_BASE) | |
1962 | taken_edge->probability = REG_BR_PROB_BASE; | |
1963 | } | |
1964 | else | |
1965 | taken_edge = bb->succ; | |
1966 | ||
1967 | bsi_remove (&bsi); | |
1968 | taken_edge->flags = EDGE_FALLTHRU; | |
1969 | ||
1970 | /* We removed some paths from the cfg. */ | |
1971 | if (dom_computed[CDI_DOMINATORS] >= DOM_CONS_OK) | |
1972 | dom_computed[CDI_DOMINATORS] = DOM_CONS_OK; | |
1973 | ||
1974 | return retval; | |
1975 | } | |
1976 | ||
1977 | ||
1978 | /* Given a control block BB and a constant value VAL, return the edge that | |
1979 | will be taken out of the block. If VAL does not match a unique edge, | |
1980 | NULL is returned. */ | |
1981 | ||
1982 | edge | |
1983 | find_taken_edge (basic_block bb, tree val) | |
1984 | { | |
1985 | tree stmt; | |
1986 | ||
1987 | stmt = last_stmt (bb); | |
1988 | ||
1989 | #if defined ENABLE_CHECKING | |
1990 | if (stmt == NULL_TREE || !is_ctrl_stmt (stmt)) | |
1991 | abort (); | |
1992 | #endif | |
1993 | ||
1994 | /* If VAL is not a constant, we can't determine which edge might | |
1995 | be taken. */ | |
1996 | if (val == NULL || !really_constant_p (val)) | |
1997 | return NULL; | |
1998 | ||
1999 | if (TREE_CODE (stmt) == COND_EXPR) | |
2000 | return find_taken_edge_cond_expr (bb, val); | |
2001 | ||
2002 | if (TREE_CODE (stmt) == SWITCH_EXPR) | |
2003 | return find_taken_edge_switch_expr (bb, val); | |
2004 | ||
2005 | return bb->succ; | |
2006 | } | |
2007 | ||
2008 | ||
2009 | /* Given a constant value VAL and the entry block BB to a COND_EXPR | |
2010 | statement, determine which of the two edges will be taken out of the | |
2011 | block. Return NULL if either edge may be taken. */ | |
2012 | ||
2013 | static edge | |
2014 | find_taken_edge_cond_expr (basic_block bb, tree val) | |
2015 | { | |
2016 | edge true_edge, false_edge; | |
2017 | ||
2018 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
2019 | ||
2020 | /* If both edges of the branch lead to the same basic block, it doesn't | |
2021 | matter which edge is taken. */ | |
2022 | if (true_edge->dest == false_edge->dest) | |
2023 | return true_edge; | |
2024 | ||
2025 | /* Otherwise, try to determine which branch of the if() will be taken. | |
2026 | If VAL is a constant but it can't be reduced to a 0 or a 1, then | |
2027 | we don't really know which edge will be taken at runtime. This | |
2028 | may happen when comparing addresses (e.g., if (&var1 == 4)). */ | |
2029 | if (integer_nonzerop (val)) | |
2030 | return true_edge; | |
2031 | else if (integer_zerop (val)) | |
2032 | return false_edge; | |
2033 | else | |
2034 | return NULL; | |
2035 | } | |
2036 | ||
2037 | ||
2038 | /* Given a constant value VAL and the entry block BB to a SWITCH_EXPR | |
2039 | statement, determine which edge will be taken out of the block. Return | |
2040 | NULL if any edge may be taken. */ | |
2041 | ||
2042 | static edge | |
2043 | find_taken_edge_switch_expr (basic_block bb, tree val) | |
2044 | { | |
2045 | tree switch_expr, taken_case; | |
2046 | basic_block dest_bb; | |
2047 | edge e; | |
2048 | ||
2049 | if (TREE_CODE (val) != INTEGER_CST) | |
2050 | return NULL; | |
2051 | ||
2052 | switch_expr = last_stmt (bb); | |
2053 | taken_case = find_case_label_for_value (switch_expr, val); | |
2054 | dest_bb = label_to_block (CASE_LABEL (taken_case)); | |
2055 | ||
2056 | e = find_edge (bb, dest_bb); | |
2057 | if (!e) | |
2058 | abort (); | |
2059 | return e; | |
2060 | } | |
2061 | ||
2062 | ||
f667741c SB |
2063 | /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL. |
2064 | We can make optimal use here of the fact that the case labels are | |
2065 | sorted: We can do a binary search for a case matching VAL. */ | |
6de9cd9a DN |
2066 | |
2067 | static tree | |
2068 | find_case_label_for_value (tree switch_expr, tree val) | |
2069 | { | |
2070 | tree vec = SWITCH_LABELS (switch_expr); | |
f667741c SB |
2071 | size_t low, high, n = TREE_VEC_LENGTH (vec); |
2072 | tree default_case = TREE_VEC_ELT (vec, n - 1); | |
6de9cd9a | 2073 | |
f667741c | 2074 | for (low = -1, high = n - 1; high - low > 1; ) |
6de9cd9a | 2075 | { |
f667741c | 2076 | size_t i = (high + low) / 2; |
6de9cd9a | 2077 | tree t = TREE_VEC_ELT (vec, i); |
f667741c SB |
2078 | int cmp; |
2079 | ||
2080 | /* Cache the result of comparing CASE_LOW and val. */ | |
2081 | cmp = tree_int_cst_compare (CASE_LOW (t), val); | |
6de9cd9a | 2082 | |
f667741c SB |
2083 | if (cmp > 0) |
2084 | high = i; | |
2085 | else | |
2086 | low = i; | |
2087 | ||
2088 | if (CASE_HIGH (t) == NULL) | |
6de9cd9a | 2089 | { |
f667741c SB |
2090 | /* A singe-valued case label. */ |
2091 | if (cmp == 0) | |
6de9cd9a DN |
2092 | return t; |
2093 | } | |
2094 | else | |
2095 | { | |
2096 | /* A case range. We can only handle integer ranges. */ | |
f667741c | 2097 | if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0) |
6de9cd9a DN |
2098 | return t; |
2099 | } | |
2100 | } | |
2101 | ||
6de9cd9a DN |
2102 | return default_case; |
2103 | } | |
2104 | ||
2105 | ||
2106 | /* If all the PHI nodes in DEST have alternatives for E1 and E2 and | |
2107 | those alternatives are equal in each of the PHI nodes, then return | |
2108 | true, else return false. */ | |
2109 | ||
2110 | static bool | |
2111 | phi_alternatives_equal (basic_block dest, edge e1, edge e2) | |
2112 | { | |
2113 | tree phi, val1, val2; | |
2114 | int n1, n2; | |
2115 | ||
17192884 | 2116 | for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
2117 | { |
2118 | n1 = phi_arg_from_edge (phi, e1); | |
2119 | n2 = phi_arg_from_edge (phi, e2); | |
2120 | ||
2121 | #ifdef ENABLE_CHECKING | |
2122 | if (n1 < 0 || n2 < 0) | |
2123 | abort (); | |
2124 | #endif | |
2125 | ||
2126 | val1 = PHI_ARG_DEF (phi, n1); | |
2127 | val2 = PHI_ARG_DEF (phi, n2); | |
2128 | ||
2129 | if (!operand_equal_p (val1, val2, 0)) | |
2130 | return false; | |
2131 | } | |
2132 | ||
2133 | return true; | |
2134 | } | |
2135 | ||
2136 | ||
2137 | /* Computing the Dominance Frontier: | |
2138 | ||
2139 | As described in Morgan, section 3.5, this may be done simply by | |
2140 | walking the dominator tree bottom-up, computing the frontier for | |
2141 | the children before the parent. When considering a block B, | |
2142 | there are two cases: | |
2143 | ||
2144 | (1) A flow graph edge leaving B that does not lead to a child | |
2145 | of B in the dominator tree must be a block that is either equal | |
2146 | to B or not dominated by B. Such blocks belong in the frontier | |
2147 | of B. | |
2148 | ||
2149 | (2) Consider a block X in the frontier of one of the children C | |
2150 | of B. If X is not equal to B and is not dominated by B, it | |
2151 | is in the frontier of B. */ | |
2152 | ||
2153 | static void | |
2154 | compute_dominance_frontiers_1 (bitmap *frontiers, basic_block bb, sbitmap done) | |
2155 | { | |
2156 | edge e; | |
2157 | basic_block c; | |
2158 | ||
2159 | SET_BIT (done, bb->index); | |
2160 | ||
2161 | /* Do the frontier of the children first. Not all children in the | |
2162 | dominator tree (blocks dominated by this one) are children in the | |
2163 | CFG, so check all blocks. */ | |
2164 | for (c = first_dom_son (CDI_DOMINATORS, bb); | |
2165 | c; | |
2166 | c = next_dom_son (CDI_DOMINATORS, c)) | |
2167 | { | |
2168 | if (! TEST_BIT (done, c->index)) | |
2169 | compute_dominance_frontiers_1 (frontiers, c, done); | |
2170 | } | |
2171 | ||
2172 | /* Find blocks conforming to rule (1) above. */ | |
2173 | for (e = bb->succ; e; e = e->succ_next) | |
2174 | { | |
2175 | if (e->dest == EXIT_BLOCK_PTR) | |
2176 | continue; | |
2177 | if (get_immediate_dominator (CDI_DOMINATORS, e->dest) != bb) | |
2178 | bitmap_set_bit (frontiers[bb->index], e->dest->index); | |
2179 | } | |
2180 | ||
2181 | /* Find blocks conforming to rule (2). */ | |
2182 | for (c = first_dom_son (CDI_DOMINATORS, bb); | |
2183 | c; | |
2184 | c = next_dom_son (CDI_DOMINATORS, c)) | |
2185 | { | |
2186 | int x; | |
2187 | ||
2188 | EXECUTE_IF_SET_IN_BITMAP (frontiers[c->index], 0, x, | |
2189 | { | |
2190 | if (get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (x)) != bb) | |
2191 | bitmap_set_bit (frontiers[bb->index], x); | |
2192 | }); | |
2193 | } | |
2194 | } | |
2195 | ||
2196 | ||
2197 | void | |
2198 | compute_dominance_frontiers (bitmap *frontiers) | |
2199 | { | |
2200 | sbitmap done = sbitmap_alloc (last_basic_block); | |
2201 | ||
2202 | timevar_push (TV_DOM_FRONTIERS); | |
2203 | ||
2204 | sbitmap_zero (done); | |
2205 | ||
2206 | compute_dominance_frontiers_1 (frontiers, ENTRY_BLOCK_PTR->succ->dest, done); | |
2207 | ||
2208 | sbitmap_free (done); | |
2209 | ||
2210 | timevar_pop (TV_DOM_FRONTIERS); | |
2211 | } | |
2212 | ||
2213 | ||
2214 | ||
2215 | /*--------------------------------------------------------------------------- | |
2216 | Debugging functions | |
2217 | ---------------------------------------------------------------------------*/ | |
2218 | ||
2219 | /* Dump tree-specific information of block BB to file OUTF. */ | |
2220 | ||
2221 | void | |
2222 | tree_dump_bb (basic_block bb, FILE *outf, int indent) | |
2223 | { | |
2224 | dump_generic_bb (outf, bb, indent, TDF_VOPS); | |
2225 | } | |
2226 | ||
2227 | ||
2228 | /* Dump a basic block on stderr. */ | |
2229 | ||
2230 | void | |
2231 | debug_tree_bb (basic_block bb) | |
2232 | { | |
2233 | dump_bb (bb, stderr, 0); | |
2234 | } | |
2235 | ||
2236 | ||
2237 | /* Dump basic block with index N on stderr. */ | |
2238 | ||
2239 | basic_block | |
2240 | debug_tree_bb_n (int n) | |
2241 | { | |
2242 | debug_tree_bb (BASIC_BLOCK (n)); | |
2243 | return BASIC_BLOCK (n); | |
2244 | } | |
2245 | ||
2246 | ||
2247 | /* Dump the CFG on stderr. | |
2248 | ||
2249 | FLAGS are the same used by the tree dumping functions | |
2250 | (see TDF_* in tree.h). */ | |
2251 | ||
2252 | void | |
2253 | debug_tree_cfg (int flags) | |
2254 | { | |
2255 | dump_tree_cfg (stderr, flags); | |
2256 | } | |
2257 | ||
2258 | ||
2259 | /* Dump the program showing basic block boundaries on the given FILE. | |
2260 | ||
2261 | FLAGS are the same used by the tree dumping functions (see TDF_* in | |
2262 | tree.h). */ | |
2263 | ||
2264 | void | |
2265 | dump_tree_cfg (FILE *file, int flags) | |
2266 | { | |
2267 | if (flags & TDF_DETAILS) | |
2268 | { | |
2269 | const char *funcname | |
673fda6b | 2270 | = lang_hooks.decl_printable_name (current_function_decl, 2); |
6de9cd9a DN |
2271 | |
2272 | fputc ('\n', file); | |
2273 | fprintf (file, ";; Function %s\n\n", funcname); | |
2274 | fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n", | |
2275 | n_basic_blocks, n_edges, last_basic_block); | |
2276 | ||
2277 | brief_dump_cfg (file); | |
2278 | fprintf (file, "\n"); | |
2279 | } | |
2280 | ||
2281 | if (flags & TDF_STATS) | |
2282 | dump_cfg_stats (file); | |
2283 | ||
2284 | dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS); | |
2285 | } | |
2286 | ||
2287 | ||
2288 | /* Dump CFG statistics on FILE. */ | |
2289 | ||
2290 | void | |
2291 | dump_cfg_stats (FILE *file) | |
2292 | { | |
2293 | static long max_num_merged_labels = 0; | |
2294 | unsigned long size, total = 0; | |
2295 | long n_edges; | |
2296 | basic_block bb; | |
2297 | const char * const fmt_str = "%-30s%-13s%12s\n"; | |
2298 | const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n"; | |
2299 | const char * const fmt_str_3 = "%-43s%11lu%c\n"; | |
2300 | const char *funcname | |
673fda6b | 2301 | = lang_hooks.decl_printable_name (current_function_decl, 2); |
6de9cd9a DN |
2302 | |
2303 | ||
2304 | fprintf (file, "\nCFG Statistics for %s\n\n", funcname); | |
2305 | ||
2306 | fprintf (file, "---------------------------------------------------------\n"); | |
2307 | fprintf (file, fmt_str, "", " Number of ", "Memory"); | |
2308 | fprintf (file, fmt_str, "", " instances ", "used "); | |
2309 | fprintf (file, "---------------------------------------------------------\n"); | |
2310 | ||
2311 | size = n_basic_blocks * sizeof (struct basic_block_def); | |
2312 | total += size; | |
2313 | fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks, SCALE (size), | |
2314 | LABEL (size)); | |
2315 | ||
2316 | n_edges = 0; | |
2317 | FOR_EACH_BB (bb) | |
2318 | { | |
2319 | edge e; | |
2320 | for (e = bb->succ; e; e = e->succ_next) | |
2321 | n_edges++; | |
2322 | } | |
2323 | size = n_edges * sizeof (struct edge_def); | |
2324 | total += size; | |
2325 | fprintf (file, fmt_str_1, "Edges", n_edges, SCALE (size), LABEL (size)); | |
2326 | ||
2327 | size = n_basic_blocks * sizeof (struct bb_ann_d); | |
2328 | total += size; | |
2329 | fprintf (file, fmt_str_1, "Basic block annotations", n_basic_blocks, | |
2330 | SCALE (size), LABEL (size)); | |
2331 | ||
2332 | fprintf (file, "---------------------------------------------------------\n"); | |
2333 | fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total), | |
2334 | LABEL (total)); | |
2335 | fprintf (file, "---------------------------------------------------------\n"); | |
2336 | fprintf (file, "\n"); | |
2337 | ||
2338 | if (cfg_stats.num_merged_labels > max_num_merged_labels) | |
2339 | max_num_merged_labels = cfg_stats.num_merged_labels; | |
2340 | ||
2341 | fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n", | |
2342 | cfg_stats.num_merged_labels, max_num_merged_labels); | |
2343 | ||
2344 | fprintf (file, "\n"); | |
2345 | } | |
2346 | ||
2347 | ||
2348 | /* Dump CFG statistics on stderr. Keep extern so that it's always | |
2349 | linked in the final executable. */ | |
2350 | ||
2351 | void | |
2352 | debug_cfg_stats (void) | |
2353 | { | |
2354 | dump_cfg_stats (stderr); | |
2355 | } | |
2356 | ||
2357 | ||
2358 | /* Dump the flowgraph to a .vcg FILE. */ | |
2359 | ||
2360 | static void | |
2361 | tree_cfg2vcg (FILE *file) | |
2362 | { | |
2363 | edge e; | |
2364 | basic_block bb; | |
2365 | const char *funcname | |
673fda6b | 2366 | = lang_hooks.decl_printable_name (current_function_decl, 2); |
6de9cd9a DN |
2367 | |
2368 | /* Write the file header. */ | |
2369 | fprintf (file, "graph: { title: \"%s\"\n", funcname); | |
2370 | fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n"); | |
2371 | fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n"); | |
2372 | ||
2373 | /* Write blocks and edges. */ | |
2374 | for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) | |
2375 | { | |
2376 | fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"", | |
2377 | e->dest->index); | |
2378 | ||
2379 | if (e->flags & EDGE_FAKE) | |
2380 | fprintf (file, " linestyle: dotted priority: 10"); | |
2381 | else | |
2382 | fprintf (file, " linestyle: solid priority: 100"); | |
2383 | ||
2384 | fprintf (file, " }\n"); | |
2385 | } | |
2386 | fputc ('\n', file); | |
2387 | ||
2388 | FOR_EACH_BB (bb) | |
2389 | { | |
2390 | enum tree_code head_code, end_code; | |
2391 | const char *head_name, *end_name; | |
2392 | int head_line = 0; | |
2393 | int end_line = 0; | |
2394 | tree first = first_stmt (bb); | |
2395 | tree last = last_stmt (bb); | |
2396 | ||
2397 | if (first) | |
2398 | { | |
2399 | head_code = TREE_CODE (first); | |
2400 | head_name = tree_code_name[head_code]; | |
2401 | head_line = get_lineno (first); | |
2402 | } | |
2403 | else | |
2404 | head_name = "no-statement"; | |
2405 | ||
2406 | if (last) | |
2407 | { | |
2408 | end_code = TREE_CODE (last); | |
2409 | end_name = tree_code_name[end_code]; | |
2410 | end_line = get_lineno (last); | |
2411 | } | |
2412 | else | |
2413 | end_name = "no-statement"; | |
2414 | ||
2415 | fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n", | |
2416 | bb->index, bb->index, head_name, head_line, end_name, | |
2417 | end_line); | |
2418 | ||
2419 | for (e = bb->succ; e; e = e->succ_next) | |
2420 | { | |
2421 | if (e->dest == EXIT_BLOCK_PTR) | |
2422 | fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index); | |
2423 | else | |
2424 | fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index); | |
2425 | ||
2426 | if (e->flags & EDGE_FAKE) | |
2427 | fprintf (file, " priority: 10 linestyle: dotted"); | |
2428 | else | |
2429 | fprintf (file, " priority: 100 linestyle: solid"); | |
2430 | ||
2431 | fprintf (file, " }\n"); | |
2432 | } | |
2433 | ||
2434 | if (bb->next_bb != EXIT_BLOCK_PTR) | |
2435 | fputc ('\n', file); | |
2436 | } | |
2437 | ||
2438 | fputs ("}\n\n", file); | |
2439 | } | |
2440 | ||
2441 | ||
2442 | ||
2443 | /*--------------------------------------------------------------------------- | |
2444 | Miscellaneous helpers | |
2445 | ---------------------------------------------------------------------------*/ | |
2446 | ||
2447 | /* Return true if T represents a stmt that always transfers control. */ | |
2448 | ||
2449 | bool | |
2450 | is_ctrl_stmt (tree t) | |
2451 | { | |
2452 | return (TREE_CODE (t) == COND_EXPR | |
2453 | || TREE_CODE (t) == SWITCH_EXPR | |
2454 | || TREE_CODE (t) == GOTO_EXPR | |
2455 | || TREE_CODE (t) == RETURN_EXPR | |
2456 | || TREE_CODE (t) == RESX_EXPR); | |
2457 | } | |
2458 | ||
2459 | ||
2460 | /* Return true if T is a statement that may alter the flow of control | |
2461 | (e.g., a call to a non-returning function). */ | |
2462 | ||
2463 | bool | |
2464 | is_ctrl_altering_stmt (tree t) | |
2465 | { | |
2466 | tree call = t; | |
2467 | ||
2468 | #if defined ENABLE_CHECKING | |
2469 | if (t == NULL) | |
2470 | abort (); | |
2471 | #endif | |
2472 | ||
2473 | switch (TREE_CODE (t)) | |
2474 | { | |
2475 | case MODIFY_EXPR: | |
2476 | /* A MODIFY_EXPR with a rhs of a call has the characteristics | |
2477 | of the call. */ | |
2478 | call = TREE_OPERAND (t, 1); | |
2479 | if (TREE_CODE (call) != CALL_EXPR) | |
2480 | break; | |
2481 | /* FALLTHRU */ | |
2482 | ||
2483 | case CALL_EXPR: | |
2484 | /* A non-pure/const CALL_EXPR alters flow control if the current | |
2485 | function has nonlocal labels. */ | |
2486 | if (TREE_SIDE_EFFECTS (t) | |
2487 | && current_function_has_nonlocal_label) | |
2488 | return true; | |
2489 | ||
2490 | /* A CALL_EXPR also alters control flow if it does not return. */ | |
2491 | if (call_expr_flags (call) & (ECF_NORETURN | ECF_LONGJMP)) | |
2492 | return true; | |
2493 | break; | |
2494 | ||
2495 | default: | |
2496 | return false; | |
2497 | } | |
2498 | ||
2499 | /* If a statement can throw, it alters control flow. */ | |
2500 | return tree_can_throw_internal (t); | |
2501 | } | |
2502 | ||
2503 | ||
2504 | /* Return true if T is a computed goto. */ | |
2505 | ||
2506 | bool | |
2507 | computed_goto_p (tree t) | |
2508 | { | |
2509 | return (TREE_CODE (t) == GOTO_EXPR | |
2510 | && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL); | |
2511 | } | |
2512 | ||
2513 | ||
2514 | /* Checks whether EXPR is a simple local goto. */ | |
2515 | ||
2516 | bool | |
2517 | simple_goto_p (tree expr) | |
2518 | { | |
2519 | return (TREE_CODE (expr) == GOTO_EXPR | |
2520 | && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL | |
2521 | && (decl_function_context (GOTO_DESTINATION (expr)) | |
2522 | == current_function_decl)); | |
2523 | } | |
2524 | ||
2525 | ||
2526 | /* Return true if T should start a new basic block. PREV_T is the | |
2527 | statement preceding T. It is used when T is a label or a case label. | |
2528 | Labels should only start a new basic block if their previous statement | |
2529 | wasn't a label. Otherwise, sequence of labels would generate | |
2530 | unnecessary basic blocks that only contain a single label. */ | |
2531 | ||
2532 | static inline bool | |
2533 | stmt_starts_bb_p (tree t, tree prev_t) | |
2534 | { | |
2535 | enum tree_code code; | |
2536 | ||
2537 | if (t == NULL_TREE) | |
2538 | return false; | |
2539 | ||
2540 | /* LABEL_EXPRs start a new basic block only if the preceding | |
2541 | statement wasn't a label of the same type. This prevents the | |
2542 | creation of consecutive blocks that have nothing but a single | |
2543 | label. */ | |
2544 | code = TREE_CODE (t); | |
2545 | if (code == LABEL_EXPR) | |
2546 | { | |
2547 | /* Nonlocal and computed GOTO targets always start a new block. */ | |
2548 | if (code == LABEL_EXPR | |
2549 | && (DECL_NONLOCAL (LABEL_EXPR_LABEL (t)) | |
2550 | || FORCED_LABEL (LABEL_EXPR_LABEL (t)))) | |
2551 | return true; | |
2552 | ||
2553 | if (prev_t && TREE_CODE (prev_t) == code) | |
2554 | { | |
2555 | if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t))) | |
2556 | return true; | |
2557 | ||
2558 | cfg_stats.num_merged_labels++; | |
2559 | return false; | |
2560 | } | |
2561 | else | |
2562 | return true; | |
2563 | } | |
2564 | ||
2565 | return false; | |
2566 | } | |
2567 | ||
2568 | ||
2569 | /* Return true if T should end a basic block. */ | |
2570 | ||
2571 | bool | |
2572 | stmt_ends_bb_p (tree t) | |
2573 | { | |
2574 | return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t); | |
2575 | } | |
2576 | ||
2577 | ||
2578 | /* Add gotos that used to be represented implicitly in the CFG. */ | |
2579 | ||
2580 | void | |
2581 | disband_implicit_edges (void) | |
2582 | { | |
2583 | basic_block bb; | |
2584 | block_stmt_iterator last; | |
2585 | edge e; | |
2586 | tree stmt, label, forward; | |
2587 | ||
2588 | FOR_EACH_BB (bb) | |
2589 | { | |
2590 | last = bsi_last (bb); | |
2591 | stmt = last_stmt (bb); | |
2592 | ||
2593 | if (stmt && TREE_CODE (stmt) == COND_EXPR) | |
2594 | { | |
2595 | /* Remove superfluous gotos from COND_EXPR branches. Moved | |
2596 | from cfg_remove_useless_stmts here since it violates the | |
2597 | invariants for tree--cfg correspondence and thus fits better | |
2598 | here where we do it anyway. */ | |
2599 | for (e = bb->succ; e; e = e->succ_next) | |
2600 | { | |
2601 | if (e->dest != bb->next_bb) | |
2602 | continue; | |
2603 | ||
2604 | if (e->flags & EDGE_TRUE_VALUE) | |
2605 | COND_EXPR_THEN (stmt) = build_empty_stmt (); | |
2606 | else if (e->flags & EDGE_FALSE_VALUE) | |
2607 | COND_EXPR_ELSE (stmt) = build_empty_stmt (); | |
2608 | else | |
2609 | abort (); | |
2610 | e->flags |= EDGE_FALLTHRU; | |
2611 | } | |
2612 | ||
2613 | continue; | |
2614 | } | |
2615 | ||
2616 | if (stmt && TREE_CODE (stmt) == RETURN_EXPR) | |
2617 | { | |
2618 | /* Remove the RETURN_EXPR if we may fall though to the exit | |
2619 | instead. */ | |
2620 | if (!bb->succ | |
2621 | || bb->succ->succ_next | |
2622 | || bb->succ->dest != EXIT_BLOCK_PTR) | |
2623 | abort (); | |
2624 | ||
2625 | if (bb->next_bb == EXIT_BLOCK_PTR | |
2626 | && !TREE_OPERAND (stmt, 0)) | |
2627 | { | |
2628 | bsi_remove (&last); | |
2629 | bb->succ->flags |= EDGE_FALLTHRU; | |
2630 | } | |
2631 | continue; | |
2632 | } | |
2633 | ||
2634 | /* There can be no fallthru edge if the last statement is a control | |
2635 | one. */ | |
2636 | if (stmt && is_ctrl_stmt (stmt)) | |
2637 | continue; | |
2638 | ||
2639 | /* Find a fallthru edge and emit the goto if necessary. */ | |
2640 | for (e = bb->succ; e; e = e->succ_next) | |
2641 | if (e->flags & EDGE_FALLTHRU) | |
2642 | break; | |
2643 | ||
62b857ea | 2644 | if (!e || e->dest == bb->next_bb) |
6de9cd9a DN |
2645 | continue; |
2646 | ||
2647 | if (e->dest == EXIT_BLOCK_PTR) | |
2648 | abort (); | |
2649 | ||
2650 | label = tree_block_label (e->dest); | |
2651 | ||
2652 | /* If this is a goto to a goto, jump to the final destination. | |
2653 | Handles unfactoring of the computed jumps. | |
2654 | ??? Why bother putting this back together when rtl is just | |
2655 | about to take it apart again? */ | |
2656 | forward = last_and_only_stmt (e->dest); | |
2657 | if (forward | |
2658 | && TREE_CODE (forward) == GOTO_EXPR) | |
2659 | label = GOTO_DESTINATION (forward); | |
2660 | ||
62b857ea RH |
2661 | stmt = build1 (GOTO_EXPR, void_type_node, label); |
2662 | SET_EXPR_LOCUS (stmt, e->goto_locus); | |
2663 | bsi_insert_after (&last, stmt, BSI_NEW_STMT); | |
6de9cd9a DN |
2664 | e->flags &= ~EDGE_FALLTHRU; |
2665 | } | |
2666 | } | |
2667 | ||
2668 | ||
2669 | /* Remove all the blocks and edges that make up the flowgraph. */ | |
2670 | ||
2671 | void | |
2672 | delete_tree_cfg (void) | |
2673 | { | |
2674 | if (n_basic_blocks > 0) | |
2675 | free_blocks_annotations (); | |
2676 | ||
2677 | free_basic_block_vars (); | |
2678 | basic_block_info = NULL; | |
2679 | label_to_block_map = NULL; | |
2680 | free_rbi_pool (); | |
2681 | } | |
2682 | ||
2683 | ||
2684 | /* Return the first statement in basic block BB. */ | |
2685 | ||
2686 | tree | |
2687 | first_stmt (basic_block bb) | |
2688 | { | |
2689 | block_stmt_iterator i = bsi_start (bb); | |
2690 | return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE; | |
2691 | } | |
2692 | ||
2693 | ||
2694 | /* Return the last statement in basic block BB. */ | |
2695 | ||
2696 | tree | |
2697 | last_stmt (basic_block bb) | |
2698 | { | |
2699 | block_stmt_iterator b = bsi_last (bb); | |
2700 | return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE; | |
2701 | } | |
2702 | ||
2703 | ||
2704 | /* Return a pointer to the last statement in block BB. */ | |
2705 | ||
2706 | tree * | |
2707 | last_stmt_ptr (basic_block bb) | |
2708 | { | |
2709 | block_stmt_iterator last = bsi_last (bb); | |
2710 | return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL; | |
2711 | } | |
2712 | ||
2713 | ||
2714 | /* Return the last statement of an otherwise empty block. Return NULL | |
2715 | if the block is totally empty, or if it contains more than one | |
2716 | statement. */ | |
2717 | ||
2718 | tree | |
2719 | last_and_only_stmt (basic_block bb) | |
2720 | { | |
2721 | block_stmt_iterator i = bsi_last (bb); | |
2722 | tree last, prev; | |
2723 | ||
2724 | if (bsi_end_p (i)) | |
2725 | return NULL_TREE; | |
2726 | ||
2727 | last = bsi_stmt (i); | |
2728 | bsi_prev (&i); | |
2729 | if (bsi_end_p (i)) | |
2730 | return last; | |
2731 | ||
2732 | /* Empty statements should no longer appear in the instruction stream. | |
2733 | Everything that might have appeared before should be deleted by | |
2734 | remove_useless_stmts, and the optimizers should just bsi_remove | |
2735 | instead of smashing with build_empty_stmt. | |
2736 | ||
2737 | Thus the only thing that should appear here in a block containing | |
2738 | one executable statement is a label. */ | |
2739 | prev = bsi_stmt (i); | |
2740 | if (TREE_CODE (prev) == LABEL_EXPR) | |
2741 | return last; | |
2742 | else | |
2743 | return NULL_TREE; | |
2744 | } | |
2745 | ||
2746 | ||
2747 | /* Mark BB as the basic block holding statement T. */ | |
2748 | ||
2749 | void | |
2750 | set_bb_for_stmt (tree t, basic_block bb) | |
2751 | { | |
2752 | if (TREE_CODE (t) == STATEMENT_LIST) | |
2753 | { | |
2754 | tree_stmt_iterator i; | |
2755 | for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i)) | |
2756 | set_bb_for_stmt (tsi_stmt (i), bb); | |
2757 | } | |
2758 | else | |
2759 | { | |
2760 | stmt_ann_t ann = get_stmt_ann (t); | |
2761 | ann->bb = bb; | |
2762 | ||
2763 | /* If the statement is a label, add the label to block-to-labels map | |
2764 | so that we can speed up edge creation for GOTO_EXPRs. */ | |
2765 | if (TREE_CODE (t) == LABEL_EXPR) | |
2766 | { | |
2767 | int uid; | |
2768 | ||
2769 | t = LABEL_EXPR_LABEL (t); | |
2770 | uid = LABEL_DECL_UID (t); | |
2771 | if (uid == -1) | |
2772 | { | |
2773 | LABEL_DECL_UID (t) = uid = cfun->last_label_uid++; | |
2774 | if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid) | |
2775 | VARRAY_GROW (label_to_block_map, 3 * uid / 2); | |
2776 | } | |
2777 | else | |
2778 | { | |
2779 | #ifdef ENABLE_CHECKING | |
2780 | /* We're moving an existing label. Make sure that we've | |
2781 | removed it from the old block. */ | |
2782 | if (bb && VARRAY_BB (label_to_block_map, uid)) | |
2783 | abort (); | |
2784 | #endif | |
2785 | } | |
2786 | VARRAY_BB (label_to_block_map, uid) = bb; | |
2787 | } | |
2788 | } | |
2789 | } | |
2790 | ||
2791 | ||
2792 | /* Insert statement (or statement list) T before the statement | |
2793 | pointed-to by iterator I. M specifies how to update iterator I | |
2794 | after insertion (see enum bsi_iterator_update). */ | |
2795 | ||
2796 | void | |
2797 | bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) | |
2798 | { | |
2799 | set_bb_for_stmt (t, i->bb); | |
2800 | modify_stmt (t); | |
2801 | tsi_link_before (&i->tsi, t, m); | |
2802 | } | |
2803 | ||
2804 | ||
2805 | /* Insert statement (or statement list) T after the statement | |
2806 | pointed-to by iterator I. M specifies how to update iterator I | |
2807 | after insertion (see enum bsi_iterator_update). */ | |
2808 | ||
2809 | void | |
2810 | bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m) | |
2811 | { | |
2812 | set_bb_for_stmt (t, i->bb); | |
2813 | modify_stmt (t); | |
2814 | tsi_link_after (&i->tsi, t, m); | |
2815 | } | |
2816 | ||
2817 | ||
2818 | /* Remove the statement pointed to by iterator I. The iterator is updated | |
2819 | to the next statement. */ | |
2820 | ||
2821 | void | |
2822 | bsi_remove (block_stmt_iterator *i) | |
2823 | { | |
2824 | tree t = bsi_stmt (*i); | |
2825 | set_bb_for_stmt (t, NULL); | |
2826 | modify_stmt (t); | |
2827 | tsi_delink (&i->tsi); | |
2828 | } | |
2829 | ||
2830 | ||
2831 | /* Move the statement at FROM so it comes right after the statement at TO. */ | |
2832 | ||
2833 | void | |
2834 | bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to) | |
2835 | { | |
2836 | tree stmt = bsi_stmt (*from); | |
2837 | bsi_remove (from); | |
2838 | bsi_insert_after (to, stmt, BSI_SAME_STMT); | |
2839 | } | |
2840 | ||
2841 | ||
2842 | /* Move the statement at FROM so it comes right before the statement at TO. */ | |
2843 | ||
2844 | void | |
2845 | bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to) | |
2846 | { | |
2847 | tree stmt = bsi_stmt (*from); | |
2848 | bsi_remove (from); | |
2849 | bsi_insert_before (to, stmt, BSI_SAME_STMT); | |
2850 | } | |
2851 | ||
2852 | ||
2853 | /* Move the statement at FROM to the end of basic block BB. */ | |
2854 | ||
2855 | void | |
2856 | bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb) | |
2857 | { | |
2858 | block_stmt_iterator last = bsi_last (bb); | |
2859 | ||
2860 | /* Have to check bsi_end_p because it could be an empty block. */ | |
2861 | if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last))) | |
2862 | bsi_move_before (from, &last); | |
2863 | else | |
2864 | bsi_move_after (from, &last); | |
2865 | } | |
2866 | ||
2867 | ||
2868 | /* Replace the contents of the statement pointed to by iterator BSI | |
2869 | with STMT. If PRESERVE_EH_INFO is true, the exception handling | |
2870 | information of the original statement is preserved. */ | |
2871 | ||
2872 | void | |
2873 | bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info) | |
2874 | { | |
2875 | int eh_region; | |
2876 | tree orig_stmt = bsi_stmt (*bsi); | |
2877 | ||
2878 | SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt)); | |
2879 | set_bb_for_stmt (stmt, bsi->bb); | |
2880 | ||
2881 | /* Preserve EH region information from the original statement, if | |
2882 | requested by the caller. */ | |
2883 | if (preserve_eh_info) | |
2884 | { | |
2885 | eh_region = lookup_stmt_eh_region (orig_stmt); | |
2886 | if (eh_region >= 0) | |
2887 | add_stmt_to_eh_region (stmt, eh_region); | |
2888 | } | |
2889 | ||
2890 | *bsi_stmt_ptr (*bsi) = stmt; | |
2891 | modify_stmt (stmt); | |
2892 | } | |
2893 | ||
2894 | ||
2895 | /* Insert the statement pointed-to by BSI into edge E. Every attempt | |
2896 | is made to place the statement in an existing basic block, but | |
2897 | sometimes that isn't possible. When it isn't possible, the edge is | |
2898 | split and the statement is added to the new block. | |
2899 | ||
2900 | In all cases, the returned *BSI points to the correct location. The | |
2901 | return value is true if insertion should be done after the location, | |
2902 | or false if it should be done before the location. */ | |
2903 | ||
2904 | static bool | |
2905 | tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi) | |
2906 | { | |
2907 | basic_block dest, src; | |
2908 | tree tmp; | |
2909 | ||
2910 | dest = e->dest; | |
2911 | restart: | |
2912 | ||
2913 | /* If the destination has one predecessor which has no PHI nodes, | |
2914 | insert there. Except for the exit block. | |
2915 | ||
2916 | The requirement for no PHI nodes could be relaxed. Basically we | |
2917 | would have to examine the PHIs to prove that none of them used | |
2918 | the value set by the statement we want to insert on E. That | |
2919 | hardly seems worth the effort. */ | |
2920 | if (dest->pred->pred_next == NULL | |
2921 | && ! phi_nodes (dest) | |
2922 | && dest != EXIT_BLOCK_PTR) | |
2923 | { | |
2924 | *bsi = bsi_start (dest); | |
2925 | if (bsi_end_p (*bsi)) | |
2926 | return true; | |
2927 | ||
2928 | /* Make sure we insert after any leading labels. */ | |
2929 | tmp = bsi_stmt (*bsi); | |
2930 | while (TREE_CODE (tmp) == LABEL_EXPR) | |
2931 | { | |
2932 | bsi_next (bsi); | |
2933 | if (bsi_end_p (*bsi)) | |
2934 | break; | |
2935 | tmp = bsi_stmt (*bsi); | |
2936 | } | |
2937 | ||
2938 | if (bsi_end_p (*bsi)) | |
2939 | { | |
2940 | *bsi = bsi_last (dest); | |
2941 | return true; | |
2942 | } | |
2943 | else | |
2944 | return false; | |
2945 | } | |
2946 | ||
2947 | /* If the source has one successor, the edge is not abnormal and | |
2948 | the last statement does not end a basic block, insert there. | |
2949 | Except for the entry block. */ | |
2950 | src = e->src; | |
2951 | if ((e->flags & EDGE_ABNORMAL) == 0 | |
2952 | && src->succ->succ_next == NULL | |
2953 | && src != ENTRY_BLOCK_PTR) | |
2954 | { | |
2955 | *bsi = bsi_last (src); | |
2956 | if (bsi_end_p (*bsi)) | |
2957 | return true; | |
2958 | ||
2959 | tmp = bsi_stmt (*bsi); | |
2960 | if (!stmt_ends_bb_p (tmp)) | |
2961 | return true; | |
ce068299 JH |
2962 | |
2963 | /* Insert code just before returning the value. We may need to decompose | |
2964 | the return in the case it contains non-trivial operand. */ | |
2965 | if (TREE_CODE (tmp) == RETURN_EXPR) | |
2966 | { | |
2967 | tree op = TREE_OPERAND (tmp, 0); | |
2968 | if (!is_gimple_val (op)) | |
2969 | { | |
2970 | if (TREE_CODE (op) != MODIFY_EXPR) | |
2971 | abort (); | |
2972 | bsi_insert_before (bsi, op, BSI_NEW_STMT); | |
2973 | TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0); | |
2974 | } | |
2975 | bsi_prev (bsi); | |
2976 | return true; | |
2977 | } | |
6de9cd9a DN |
2978 | } |
2979 | ||
2980 | /* Otherwise, create a new basic block, and split this edge. */ | |
2981 | dest = split_edge (e); | |
2982 | e = dest->pred; | |
2983 | goto restart; | |
2984 | } | |
2985 | ||
2986 | ||
2987 | /* This routine will commit all pending edge insertions, creating any new | |
2988 | basic blocks which are necessary. | |
2989 | ||
2990 | If specified, NEW_BLOCKS returns a count of the number of new basic | |
2991 | blocks which were created. */ | |
2992 | ||
2993 | void | |
2994 | bsi_commit_edge_inserts (int *new_blocks) | |
2995 | { | |
2996 | basic_block bb; | |
2997 | edge e; | |
2998 | int blocks; | |
2999 | ||
3000 | blocks = n_basic_blocks; | |
3001 | ||
3002 | bsi_commit_edge_inserts_1 (ENTRY_BLOCK_PTR->succ); | |
3003 | ||
3004 | FOR_EACH_BB (bb) | |
3005 | for (e = bb->succ; e; e = e->succ_next) | |
3006 | bsi_commit_edge_inserts_1 (e); | |
3007 | ||
3008 | if (new_blocks) | |
3009 | *new_blocks = n_basic_blocks - blocks; | |
3010 | } | |
3011 | ||
3012 | ||
3013 | /* Commit insertions pending at edge E. */ | |
3014 | ||
3015 | static void | |
3016 | bsi_commit_edge_inserts_1 (edge e) | |
3017 | { | |
3018 | if (PENDING_STMT (e)) | |
3019 | { | |
3020 | block_stmt_iterator bsi; | |
3021 | tree stmt = PENDING_STMT (e); | |
3022 | ||
3023 | PENDING_STMT (e) = NULL_TREE; | |
3024 | ||
3025 | if (tree_find_edge_insert_loc (e, &bsi)) | |
3026 | bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); | |
3027 | else | |
3028 | bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); | |
3029 | } | |
3030 | } | |
3031 | ||
3032 | ||
3033 | /* Add STMT to the pending list of edge E. No actual insertion is | |
3034 | made until a call to bsi_commit_edge_inserts () is made. */ | |
3035 | ||
3036 | void | |
3037 | bsi_insert_on_edge (edge e, tree stmt) | |
3038 | { | |
3039 | append_to_statement_list (stmt, &PENDING_STMT (e)); | |
3040 | } | |
3041 | ||
3042 | ||
3043 | /* Specialized edge insertion for SSA-PRE. FIXME: This should | |
3044 | probably disappear. The only reason it's here is because PRE needs | |
3045 | the call to tree_find_edge_insert_loc(). */ | |
3046 | ||
3047 | void pre_insert_on_edge (edge e, tree stmt); | |
3048 | ||
3049 | void | |
3050 | pre_insert_on_edge (edge e, tree stmt) | |
3051 | { | |
3052 | block_stmt_iterator bsi; | |
3053 | ||
3054 | if (PENDING_STMT (e)) | |
3055 | abort (); | |
3056 | ||
3057 | if (tree_find_edge_insert_loc (e, &bsi)) | |
3058 | bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); | |
3059 | else | |
3060 | bsi_insert_before (&bsi, stmt, BSI_NEW_STMT); | |
3061 | } | |
3062 | ||
3063 | ||
3064 | /*--------------------------------------------------------------------------- | |
3065 | Tree specific functions for CFG manipulation | |
3066 | ---------------------------------------------------------------------------*/ | |
3067 | ||
3068 | /* Split a (typically critical) edge EDGE_IN. Return the new block. | |
3069 | Abort on abnormal edges. */ | |
3070 | ||
3071 | static basic_block | |
3072 | tree_split_edge (edge edge_in) | |
3073 | { | |
3074 | basic_block new_bb, after_bb, dest, src; | |
3075 | edge new_edge, e; | |
3076 | tree phi; | |
3077 | int i, num_elem; | |
3078 | ||
3079 | /* Abnormal edges cannot be split. */ | |
3080 | if (edge_in->flags & EDGE_ABNORMAL) | |
3081 | abort (); | |
3082 | ||
3083 | src = edge_in->src; | |
3084 | dest = edge_in->dest; | |
3085 | ||
3086 | /* Place the new block in the block list. Try to keep the new block | |
3087 | near its "logical" location. This is of most help to humans looking | |
3088 | at debugging dumps. */ | |
3089 | for (e = dest->pred; e; e = e->pred_next) | |
3090 | if (e->src->next_bb == dest) | |
3091 | break; | |
3092 | if (!e) | |
3093 | after_bb = dest->prev_bb; | |
3094 | else | |
3095 | after_bb = edge_in->src; | |
3096 | ||
3097 | new_bb = create_empty_bb (after_bb); | |
3098 | new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU); | |
3099 | ||
3100 | /* Find all the PHI arguments on the original edge, and change them to | |
3101 | the new edge. Do it before redirection, so that the argument does not | |
3102 | get removed. */ | |
17192884 | 3103 | for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3104 | { |
3105 | num_elem = PHI_NUM_ARGS (phi); | |
3106 | for (i = 0; i < num_elem; i++) | |
3107 | if (PHI_ARG_EDGE (phi, i) == edge_in) | |
3108 | { | |
3109 | PHI_ARG_EDGE (phi, i) = new_edge; | |
3110 | break; | |
3111 | } | |
3112 | } | |
3113 | ||
3114 | if (!redirect_edge_and_branch (edge_in, new_bb)) | |
3115 | abort (); | |
3116 | ||
3117 | if (PENDING_STMT (edge_in)) | |
3118 | abort (); | |
3119 | ||
3120 | return new_bb; | |
3121 | } | |
3122 | ||
3123 | ||
3124 | /* Return true when BB has label LABEL in it. */ | |
3125 | ||
3126 | static bool | |
3127 | has_label_p (basic_block bb, tree label) | |
3128 | { | |
3129 | block_stmt_iterator bsi; | |
3130 | ||
3131 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3132 | { | |
3133 | tree stmt = bsi_stmt (bsi); | |
3134 | ||
3135 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
3136 | return false; | |
3137 | if (LABEL_EXPR_LABEL (stmt) == label) | |
3138 | return true; | |
3139 | } | |
3140 | return false; | |
3141 | } | |
3142 | ||
3143 | ||
3144 | /* Callback for walk_tree, check that all elements with address taken are | |
3145 | properly noticed as such. */ | |
3146 | ||
3147 | static tree | |
3148 | verify_expr (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED, | |
3149 | void *data ATTRIBUTE_UNUSED) | |
3150 | { | |
3151 | tree t = *tp, x; | |
3152 | ||
3153 | if (TYPE_P (t)) | |
3154 | *walk_subtrees = 0; | |
3155 | ||
3156 | switch (TREE_CODE (t)) | |
3157 | { | |
3158 | case SSA_NAME: | |
3159 | if (SSA_NAME_IN_FREE_LIST (t)) | |
3160 | { | |
3161 | error ("SSA name in freelist but still referenced"); | |
3162 | return *tp; | |
3163 | } | |
3164 | break; | |
3165 | ||
3166 | case MODIFY_EXPR: | |
3167 | x = TREE_OPERAND (t, 0); | |
3168 | if (TREE_CODE (x) == BIT_FIELD_REF | |
3169 | && is_gimple_reg (TREE_OPERAND (x, 0))) | |
3170 | { | |
3171 | error ("GIMPLE register modified with BIT_FIELD_REF"); | |
3172 | return *tp; | |
3173 | } | |
3174 | break; | |
3175 | ||
3176 | case ADDR_EXPR: | |
3177 | x = TREE_OPERAND (t, 0); | |
3178 | while (TREE_CODE (x) == ARRAY_REF | |
3179 | || TREE_CODE (x) == COMPONENT_REF | |
3180 | || TREE_CODE (x) == REALPART_EXPR | |
3181 | || TREE_CODE (x) == IMAGPART_EXPR) | |
3182 | x = TREE_OPERAND (x, 0); | |
3183 | if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL) | |
3184 | return NULL; | |
3185 | if (!TREE_ADDRESSABLE (x)) | |
3186 | { | |
3187 | error ("address taken, but ADDRESSABLE bit not set"); | |
3188 | return x; | |
3189 | } | |
3190 | break; | |
3191 | ||
3192 | case COND_EXPR: | |
3193 | x = TREE_OPERAND (t, 0); | |
3194 | if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE) | |
3195 | { | |
3196 | error ("non-boolean used in condition"); | |
3197 | return x; | |
3198 | } | |
3199 | break; | |
3200 | ||
3201 | case NOP_EXPR: | |
3202 | case CONVERT_EXPR: | |
3203 | case FIX_TRUNC_EXPR: | |
3204 | case FIX_CEIL_EXPR: | |
3205 | case FIX_FLOOR_EXPR: | |
3206 | case FIX_ROUND_EXPR: | |
3207 | case FLOAT_EXPR: | |
3208 | case NEGATE_EXPR: | |
3209 | case ABS_EXPR: | |
3210 | case BIT_NOT_EXPR: | |
3211 | case NON_LVALUE_EXPR: | |
3212 | case TRUTH_NOT_EXPR: | |
3213 | x = TREE_OPERAND (t, 0); | |
3214 | /* We check for constants explicitly since they are not considered | |
3215 | gimple invariants if they overflowed. */ | |
3216 | if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c' | |
3217 | && !is_gimple_val (x)) | |
3218 | { | |
3219 | error ("Invalid operand to unary operator"); | |
3220 | return x; | |
3221 | } | |
3222 | break; | |
3223 | ||
3224 | case REALPART_EXPR: | |
3225 | case IMAGPART_EXPR: | |
3226 | break; | |
3227 | ||
3228 | case LT_EXPR: | |
3229 | case LE_EXPR: | |
3230 | case GT_EXPR: | |
3231 | case GE_EXPR: | |
3232 | case EQ_EXPR: | |
3233 | case NE_EXPR: | |
3234 | case UNORDERED_EXPR: | |
3235 | case ORDERED_EXPR: | |
3236 | case UNLT_EXPR: | |
3237 | case UNLE_EXPR: | |
3238 | case UNGT_EXPR: | |
3239 | case UNGE_EXPR: | |
3240 | case UNEQ_EXPR: | |
d1a7edaf | 3241 | case LTGT_EXPR: |
6de9cd9a DN |
3242 | case PLUS_EXPR: |
3243 | case MINUS_EXPR: | |
3244 | case MULT_EXPR: | |
3245 | case TRUNC_DIV_EXPR: | |
3246 | case CEIL_DIV_EXPR: | |
3247 | case FLOOR_DIV_EXPR: | |
3248 | case ROUND_DIV_EXPR: | |
3249 | case TRUNC_MOD_EXPR: | |
3250 | case CEIL_MOD_EXPR: | |
3251 | case FLOOR_MOD_EXPR: | |
3252 | case ROUND_MOD_EXPR: | |
3253 | case RDIV_EXPR: | |
3254 | case EXACT_DIV_EXPR: | |
3255 | case MIN_EXPR: | |
3256 | case MAX_EXPR: | |
3257 | case LSHIFT_EXPR: | |
3258 | case RSHIFT_EXPR: | |
3259 | case LROTATE_EXPR: | |
3260 | case RROTATE_EXPR: | |
3261 | case BIT_IOR_EXPR: | |
3262 | case BIT_XOR_EXPR: | |
3263 | case BIT_AND_EXPR: | |
3264 | x = TREE_OPERAND (t, 0); | |
3265 | /* We check for constants explicitly since they are not considered | |
3266 | gimple invariants if they overflowed. */ | |
3267 | if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c' | |
3268 | && !is_gimple_val (x)) | |
3269 | { | |
3270 | error ("Invalid operand to binary operator"); | |
3271 | return x; | |
3272 | } | |
3273 | x = TREE_OPERAND (t, 1); | |
3274 | /* We check for constants explicitly since they are not considered | |
3275 | gimple invariants if they overflowed. */ | |
3276 | if (TREE_CODE_CLASS (TREE_CODE (x)) != 'c' | |
3277 | && !is_gimple_val (x)) | |
3278 | { | |
3279 | error ("Invalid operand to binary operator"); | |
3280 | return x; | |
3281 | } | |
3282 | break; | |
3283 | ||
3284 | default: | |
3285 | break; | |
3286 | } | |
3287 | return NULL; | |
3288 | } | |
3289 | ||
3290 | ||
3291 | /* Verify STMT, return true if STMT is not in GIMPLE form. | |
3292 | TODO: Implement type checking. */ | |
3293 | ||
3294 | static bool | |
3295 | verify_stmt (tree stmt) | |
3296 | { | |
3297 | tree addr; | |
3298 | ||
3299 | if (!is_gimple_stmt (stmt)) | |
3300 | { | |
3301 | error ("Is not a valid GIMPLE statement."); | |
3302 | debug_generic_stmt (stmt); | |
3303 | return true; | |
3304 | } | |
3305 | ||
3306 | addr = walk_tree (&stmt, verify_expr, NULL, NULL); | |
3307 | if (addr) | |
3308 | { | |
3309 | debug_generic_stmt (addr); | |
3310 | return true; | |
3311 | } | |
3312 | ||
3313 | return false; | |
3314 | } | |
3315 | ||
3316 | ||
3317 | /* Return true when the T can be shared. */ | |
3318 | ||
3319 | static bool | |
3320 | tree_node_can_be_shared (tree t) | |
3321 | { | |
3322 | if (TYPE_P (t) || DECL_P (t) | |
3323 | /* We check for constants explicitly since they are not considered | |
3324 | gimple invariants if they overflowed. */ | |
3325 | || TREE_CODE_CLASS (TREE_CODE (t)) == 'c' | |
3326 | || is_gimple_min_invariant (t) | |
3327 | || TREE_CODE (t) == SSA_NAME) | |
3328 | return true; | |
3329 | ||
3330 | while ((TREE_CODE (t) == ARRAY_REF | |
3331 | /* We check for constants explicitly since they are not considered | |
3332 | gimple invariants if they overflowed. */ | |
3333 | && (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (t, 1))) == 'c' | |
3334 | || is_gimple_min_invariant (TREE_OPERAND (t, 1)))) | |
3335 | || (TREE_CODE (t) == COMPONENT_REF | |
3336 | || TREE_CODE (t) == REALPART_EXPR | |
3337 | || TREE_CODE (t) == IMAGPART_EXPR)) | |
3338 | t = TREE_OPERAND (t, 0); | |
3339 | ||
3340 | if (DECL_P (t)) | |
3341 | return true; | |
3342 | ||
3343 | return false; | |
3344 | } | |
3345 | ||
3346 | ||
3347 | /* Called via walk_trees. Verify tree sharing. */ | |
3348 | ||
3349 | static tree | |
3350 | verify_node_sharing (tree * tp, int *walk_subtrees, void *data) | |
3351 | { | |
3352 | htab_t htab = (htab_t) data; | |
3353 | void **slot; | |
3354 | ||
3355 | if (tree_node_can_be_shared (*tp)) | |
3356 | { | |
3357 | *walk_subtrees = false; | |
3358 | return NULL; | |
3359 | } | |
3360 | ||
3361 | slot = htab_find_slot (htab, *tp, INSERT); | |
3362 | if (*slot) | |
3363 | return *slot; | |
3364 | *slot = *tp; | |
3365 | ||
3366 | return NULL; | |
3367 | } | |
3368 | ||
3369 | ||
3370 | /* Verify the GIMPLE statement chain. */ | |
3371 | ||
3372 | void | |
3373 | verify_stmts (void) | |
3374 | { | |
3375 | basic_block bb; | |
3376 | block_stmt_iterator bsi; | |
3377 | bool err = false; | |
3378 | htab_t htab; | |
3379 | tree addr; | |
3380 | ||
3381 | timevar_push (TV_TREE_STMT_VERIFY); | |
3382 | htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL); | |
3383 | ||
3384 | FOR_EACH_BB (bb) | |
3385 | { | |
3386 | tree phi; | |
3387 | int i; | |
3388 | ||
17192884 | 3389 | for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3390 | { |
3391 | int phi_num_args = PHI_NUM_ARGS (phi); | |
3392 | ||
3393 | for (i = 0; i < phi_num_args; i++) | |
3394 | { | |
3395 | tree t = PHI_ARG_DEF (phi, i); | |
3396 | tree addr; | |
3397 | ||
3398 | /* Addressable variables do have SSA_NAMEs but they | |
3399 | are not considered gimple values. */ | |
3400 | if (TREE_CODE (t) != SSA_NAME | |
3401 | && TREE_CODE (t) != FUNCTION_DECL | |
3402 | && !is_gimple_val (t)) | |
3403 | { | |
3404 | error ("PHI def is not a GIMPLE value"); | |
3405 | debug_generic_stmt (phi); | |
3406 | debug_generic_stmt (t); | |
3407 | err |= true; | |
3408 | } | |
3409 | ||
3410 | addr = walk_tree (&t, verify_expr, NULL, NULL); | |
3411 | if (addr) | |
3412 | { | |
3413 | debug_generic_stmt (addr); | |
3414 | err |= true; | |
3415 | } | |
3416 | ||
3417 | addr = walk_tree (&t, verify_node_sharing, htab, NULL); | |
3418 | if (addr) | |
3419 | { | |
3420 | error ("Incorrect sharing of tree nodes"); | |
3421 | debug_generic_stmt (phi); | |
3422 | debug_generic_stmt (addr); | |
3423 | err |= true; | |
3424 | } | |
3425 | } | |
3426 | } | |
3427 | ||
3428 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3429 | { | |
3430 | tree stmt = bsi_stmt (bsi); | |
3431 | err |= verify_stmt (stmt); | |
3432 | addr = walk_tree (&stmt, verify_node_sharing, htab, NULL); | |
3433 | if (addr) | |
3434 | { | |
3435 | error ("Incorrect sharing of tree nodes"); | |
3436 | debug_generic_stmt (stmt); | |
3437 | debug_generic_stmt (addr); | |
3438 | err |= true; | |
3439 | } | |
3440 | } | |
3441 | } | |
3442 | ||
3443 | if (err) | |
3444 | internal_error ("verify_stmts failed."); | |
3445 | ||
3446 | htab_delete (htab); | |
3447 | timevar_pop (TV_TREE_STMT_VERIFY); | |
3448 | } | |
3449 | ||
3450 | ||
3451 | /* Verifies that the flow information is OK. */ | |
3452 | ||
3453 | static int | |
3454 | tree_verify_flow_info (void) | |
3455 | { | |
3456 | int err = 0; | |
3457 | basic_block bb; | |
3458 | block_stmt_iterator bsi; | |
3459 | tree stmt; | |
3460 | edge e; | |
3461 | ||
3462 | if (ENTRY_BLOCK_PTR->stmt_list) | |
3463 | { | |
3464 | error ("ENTRY_BLOCK has a statement list associated with it\n"); | |
3465 | err = 1; | |
3466 | } | |
3467 | ||
3468 | if (EXIT_BLOCK_PTR->stmt_list) | |
3469 | { | |
3470 | error ("EXIT_BLOCK has a statement list associated with it\n"); | |
3471 | err = 1; | |
3472 | } | |
3473 | ||
3474 | for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next) | |
3475 | if (e->flags & EDGE_FALLTHRU) | |
3476 | { | |
3477 | error ("Fallthru to exit from bb %d\n", e->src->index); | |
3478 | err = 1; | |
3479 | } | |
3480 | ||
3481 | FOR_EACH_BB (bb) | |
3482 | { | |
3483 | bool found_ctrl_stmt = false; | |
3484 | ||
3485 | /* Skip labels on the start of basic block. */ | |
3486 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3487 | { | |
3488 | if (TREE_CODE (bsi_stmt (bsi)) != LABEL_EXPR) | |
3489 | break; | |
3490 | ||
3491 | if (label_to_block (LABEL_EXPR_LABEL (bsi_stmt (bsi))) != bb) | |
3492 | { | |
3493 | error ("Label %s to block does not match in bb %d\n", | |
3494 | IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))), | |
3495 | bb->index); | |
3496 | err = 1; | |
3497 | } | |
3498 | ||
3499 | if (decl_function_context (LABEL_EXPR_LABEL (bsi_stmt (bsi))) | |
3500 | != current_function_decl) | |
3501 | { | |
3502 | error ("Label %s has incorrect context in bb %d\n", | |
3503 | IDENTIFIER_POINTER (DECL_NAME (bsi_stmt (bsi))), | |
3504 | bb->index); | |
3505 | err = 1; | |
3506 | } | |
3507 | } | |
3508 | ||
3509 | /* Verify that body of basic block BB is free of control flow. */ | |
3510 | for (; !bsi_end_p (bsi); bsi_next (&bsi)) | |
3511 | { | |
3512 | tree stmt = bsi_stmt (bsi); | |
3513 | ||
3514 | if (found_ctrl_stmt) | |
3515 | { | |
3516 | error ("Control flow in the middle of basic block %d\n", | |
3517 | bb->index); | |
3518 | err = 1; | |
3519 | } | |
3520 | ||
3521 | if (stmt_ends_bb_p (stmt)) | |
3522 | found_ctrl_stmt = true; | |
3523 | ||
3524 | if (TREE_CODE (stmt) == LABEL_EXPR) | |
3525 | { | |
3526 | error ("Label %s in the middle of basic block %d\n", | |
3527 | IDENTIFIER_POINTER (DECL_NAME (stmt)), | |
3528 | bb->index); | |
3529 | err = 1; | |
3530 | } | |
3531 | } | |
3532 | bsi = bsi_last (bb); | |
3533 | if (bsi_end_p (bsi)) | |
3534 | continue; | |
3535 | ||
3536 | stmt = bsi_stmt (bsi); | |
3537 | ||
3538 | if (is_ctrl_stmt (stmt)) | |
3539 | { | |
3540 | for (e = bb->succ; e; e = e->succ_next) | |
3541 | if (e->flags & EDGE_FALLTHRU) | |
3542 | { | |
3543 | error ("Fallthru edge after a control statement in bb %d \n", | |
3544 | bb->index); | |
3545 | err = 1; | |
3546 | } | |
3547 | } | |
3548 | ||
3549 | switch (TREE_CODE (stmt)) | |
3550 | { | |
3551 | case COND_EXPR: | |
3552 | { | |
3553 | edge true_edge; | |
3554 | edge false_edge; | |
3555 | if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR | |
3556 | || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR) | |
3557 | { | |
3558 | error ("Structured COND_EXPR at the end of bb %d\n", bb->index); | |
3559 | err = 1; | |
3560 | } | |
3561 | ||
3562 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
3563 | ||
3564 | if (!true_edge || !false_edge | |
3565 | || !(true_edge->flags & EDGE_TRUE_VALUE) | |
3566 | || !(false_edge->flags & EDGE_FALSE_VALUE) | |
3567 | || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) | |
3568 | || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL)) | |
3569 | || bb->succ->succ_next->succ_next) | |
3570 | { | |
3571 | error ("Wrong outgoing edge flags at end of bb %d\n", | |
3572 | bb->index); | |
3573 | err = 1; | |
3574 | } | |
3575 | ||
3576 | if (!has_label_p (true_edge->dest, | |
3577 | GOTO_DESTINATION (COND_EXPR_THEN (stmt)))) | |
3578 | { | |
3579 | error ("`then' label does not match edge at end of bb %d\n", | |
3580 | bb->index); | |
3581 | err = 1; | |
3582 | } | |
3583 | ||
3584 | if (!has_label_p (false_edge->dest, | |
3585 | GOTO_DESTINATION (COND_EXPR_ELSE (stmt)))) | |
3586 | { | |
3587 | error ("`else' label does not match edge at end of bb %d\n", | |
3588 | bb->index); | |
3589 | err = 1; | |
3590 | } | |
3591 | } | |
3592 | break; | |
3593 | ||
3594 | case GOTO_EXPR: | |
3595 | if (simple_goto_p (stmt)) | |
3596 | { | |
3597 | error ("Explicit goto at end of bb %d\n", bb->index); | |
3598 | err = 1; | |
3599 | } | |
3600 | else | |
3601 | { | |
3602 | /* FIXME. We should double check that the labels in the | |
3603 | destination blocks have their address taken. */ | |
3604 | for (e = bb->succ; e; e = e->succ_next) | |
3605 | if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE | |
3606 | | EDGE_FALSE_VALUE)) | |
3607 | || !(e->flags & EDGE_ABNORMAL)) | |
3608 | { | |
3609 | error ("Wrong outgoing edge flags at end of bb %d\n", | |
3610 | bb->index); | |
3611 | err = 1; | |
3612 | } | |
3613 | } | |
3614 | break; | |
3615 | ||
3616 | case RETURN_EXPR: | |
3617 | if (!bb->succ || bb->succ->succ_next | |
3618 | || (bb->succ->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL | |
3619 | | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
3620 | { | |
3621 | error ("Wrong outgoing edge flags at end of bb %d\n", bb->index); | |
3622 | err = 1; | |
3623 | } | |
3624 | if (bb->succ->dest != EXIT_BLOCK_PTR) | |
3625 | { | |
3626 | error ("Return edge does not point to exit in bb %d\n", | |
3627 | bb->index); | |
3628 | err = 1; | |
3629 | } | |
3630 | break; | |
3631 | ||
3632 | case SWITCH_EXPR: | |
3633 | { | |
7853504d | 3634 | tree prev; |
6de9cd9a DN |
3635 | edge e; |
3636 | size_t i, n; | |
3637 | tree vec; | |
3638 | ||
3639 | vec = SWITCH_LABELS (stmt); | |
3640 | n = TREE_VEC_LENGTH (vec); | |
3641 | ||
3642 | /* Mark all the destination basic blocks. */ | |
3643 | for (i = 0; i < n; ++i) | |
3644 | { | |
3645 | tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
3646 | basic_block label_bb = label_to_block (lab); | |
3647 | ||
3648 | if (label_bb->aux && label_bb->aux != (void *)1) | |
3649 | abort (); | |
3650 | label_bb->aux = (void *)1; | |
3651 | } | |
3652 | ||
7853504d SB |
3653 | /* Verify that the case labels are sorted. */ |
3654 | prev = TREE_VEC_ELT (vec, 0); | |
3655 | for (i = 1; i < n - 1; ++i) | |
3656 | { | |
3657 | tree c = TREE_VEC_ELT (vec, i); | |
3658 | if (! CASE_LOW (c)) | |
3659 | { | |
3660 | error ("Found default case not at end of case vector"); | |
3661 | err = 1; | |
3662 | continue; | |
3663 | } | |
3664 | if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c))) | |
3665 | { | |
3666 | error ("Case labels not sorted:\n "); | |
3667 | print_generic_expr (stderr, prev, 0); | |
3668 | fprintf (stderr," is greater than "); | |
3669 | print_generic_expr (stderr, c, 0); | |
3670 | fprintf (stderr," but comes before it.\n"); | |
3671 | err = 1; | |
3672 | } | |
3673 | prev = c; | |
3674 | } | |
3675 | if (CASE_LOW (TREE_VEC_ELT (vec, n - 1))) | |
3676 | { | |
3677 | error ("No default case found at end of case vector"); | |
3678 | err = 1; | |
3679 | } | |
3680 | ||
6de9cd9a DN |
3681 | for (e = bb->succ; e; e = e->succ_next) |
3682 | { | |
3683 | if (!e->dest->aux) | |
3684 | { | |
3685 | error ("Extra outgoing edge %d->%d\n", | |
3686 | bb->index, e->dest->index); | |
3687 | err = 1; | |
3688 | } | |
3689 | e->dest->aux = (void *)2; | |
3690 | if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL | |
3691 | | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
3692 | { | |
3693 | error ("Wrong outgoing edge flags at end of bb %d\n", | |
3694 | bb->index); | |
3695 | err = 1; | |
3696 | } | |
3697 | } | |
3698 | ||
3699 | /* Check that we have all of them. */ | |
3700 | for (i = 0; i < n; ++i) | |
3701 | { | |
3702 | tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i)); | |
3703 | basic_block label_bb = label_to_block (lab); | |
3704 | ||
3705 | if (label_bb->aux != (void *)2) | |
3706 | { | |
3707 | error ("Missing edge %i->%i\n", | |
3708 | bb->index, label_bb->index); | |
3709 | err = 1; | |
3710 | } | |
3711 | } | |
3712 | ||
3713 | for (e = bb->succ; e; e = e->succ_next) | |
3714 | e->dest->aux = (void *)0; | |
3715 | } | |
3716 | ||
3717 | default: ; | |
3718 | } | |
3719 | } | |
3720 | ||
3721 | if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY) | |
3722 | verify_dominators (CDI_DOMINATORS); | |
3723 | ||
3724 | return err; | |
3725 | } | |
3726 | ||
3727 | ||
3728 | /* Updates phi nodes after creating forwarder block joined | |
3729 | by edge FALLTHRU. */ | |
3730 | ||
3731 | static void | |
3732 | tree_make_forwarder_block (edge fallthru) | |
3733 | { | |
3734 | edge e; | |
3735 | basic_block dummy, bb; | |
17192884 | 3736 | tree phi, new_phi, var, prev, next; |
6de9cd9a DN |
3737 | |
3738 | dummy = fallthru->src; | |
3739 | bb = fallthru->dest; | |
3740 | ||
3741 | if (!bb->pred->pred_next) | |
3742 | return; | |
3743 | ||
3744 | /* If we redirected a branch we must create new phi nodes at the | |
3745 | start of BB. */ | |
17192884 | 3746 | for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3747 | { |
3748 | var = PHI_RESULT (phi); | |
3749 | new_phi = create_phi_node (var, bb); | |
3750 | SSA_NAME_DEF_STMT (var) = new_phi; | |
3751 | PHI_RESULT (phi) = make_ssa_name (SSA_NAME_VAR (var), phi); | |
3752 | add_phi_arg (&new_phi, PHI_RESULT (phi), fallthru); | |
3753 | } | |
3754 | ||
17192884 SB |
3755 | /* Ensure that the PHI node chain is in the same order. */ |
3756 | prev = NULL; | |
3757 | for (phi = phi_nodes (bb); phi; phi = next) | |
3758 | { | |
3759 | next = PHI_CHAIN (phi); | |
3760 | PHI_CHAIN (phi) = prev; | |
3761 | prev = phi; | |
3762 | } | |
3763 | set_phi_nodes (bb, prev); | |
6de9cd9a DN |
3764 | |
3765 | /* Add the arguments we have stored on edges. */ | |
3766 | for (e = bb->pred; e; e = e->pred_next) | |
3767 | { | |
3768 | if (e == fallthru) | |
3769 | continue; | |
3770 | ||
3771 | for (phi = phi_nodes (bb), var = PENDING_STMT (e); | |
3772 | phi; | |
17192884 | 3773 | phi = PHI_CHAIN (phi), var = TREE_CHAIN (var)) |
6de9cd9a DN |
3774 | add_phi_arg (&phi, TREE_VALUE (var), e); |
3775 | ||
3776 | PENDING_STMT (e) = NULL; | |
3777 | } | |
3778 | } | |
3779 | ||
3780 | ||
3781 | /* Return true if basic block BB does nothing except pass control | |
3782 | flow to another block and that we can safely insert a label at | |
3783 | the start of the successor block. */ | |
3784 | ||
3785 | static bool | |
3786 | tree_forwarder_block_p (basic_block bb) | |
3787 | { | |
3788 | block_stmt_iterator bsi; | |
3789 | edge e; | |
3790 | ||
3791 | /* If we have already determined that this block is not forwardable, | |
3792 | then no further checks are necessary. */ | |
3793 | if (! bb_ann (bb)->forwardable) | |
3794 | return false; | |
3795 | ||
3796 | /* BB must have a single outgoing normal edge. Otherwise it can not be | |
3797 | a forwarder block. */ | |
3798 | if (!bb->succ | |
3799 | || bb->succ->succ_next | |
3800 | || bb->succ->dest == EXIT_BLOCK_PTR | |
3801 | || (bb->succ->flags & EDGE_ABNORMAL) | |
3802 | || bb == ENTRY_BLOCK_PTR) | |
3803 | { | |
3804 | bb_ann (bb)->forwardable = 0; | |
3805 | return false; | |
3806 | } | |
3807 | ||
3808 | /* Successors of the entry block are not forwarders. */ | |
3809 | for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next) | |
3810 | if (e->dest == bb) | |
3811 | { | |
3812 | bb_ann (bb)->forwardable = 0; | |
3813 | return false; | |
3814 | } | |
3815 | ||
3816 | /* BB can not have any PHI nodes. This could potentially be relaxed | |
3817 | early in compilation if we re-rewrote the variables appearing in | |
3818 | any PHI nodes in forwarder blocks. */ | |
3819 | if (phi_nodes (bb)) | |
3820 | { | |
3821 | bb_ann (bb)->forwardable = 0; | |
3822 | return false; | |
3823 | } | |
3824 | ||
3825 | /* Now walk through the statements. We can ignore labels, anything else | |
3826 | means this is not a forwarder block. */ | |
3827 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
3828 | { | |
3829 | tree stmt = bsi_stmt (bsi); | |
3830 | ||
3831 | switch (TREE_CODE (stmt)) | |
3832 | { | |
3833 | case LABEL_EXPR: | |
3834 | if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))) | |
3835 | return false; | |
3836 | break; | |
3837 | ||
3838 | default: | |
3839 | bb_ann (bb)->forwardable = 0; | |
3840 | return false; | |
3841 | } | |
3842 | } | |
3843 | ||
3844 | return true; | |
3845 | } | |
3846 | ||
3847 | ||
3848 | /* Thread jumps over empty statements. | |
3849 | ||
3850 | This code should _not_ thread over obviously equivalent conditions | |
3851 | as that requires nontrivial updates to the SSA graph. */ | |
3852 | ||
3853 | static bool | |
3854 | thread_jumps (void) | |
3855 | { | |
3856 | edge e, next, last, old; | |
3857 | basic_block bb, dest, tmp; | |
3858 | tree phi; | |
3859 | int arg; | |
3860 | bool retval = false; | |
3861 | ||
3862 | FOR_EACH_BB (bb) | |
3863 | bb_ann (bb)->forwardable = 1; | |
3864 | ||
3865 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb) | |
3866 | { | |
3867 | /* Don't waste time on unreachable blocks. */ | |
3868 | if (!bb->pred) | |
3869 | continue; | |
3870 | ||
3871 | /* Nor on forwarders. */ | |
3872 | if (tree_forwarder_block_p (bb)) | |
3873 | continue; | |
3874 | ||
3875 | /* This block is now part of a forwarding path, mark it as not | |
3876 | forwardable so that we can detect loops. This bit will be | |
3877 | reset below. */ | |
3878 | bb_ann (bb)->forwardable = 0; | |
3879 | ||
3880 | /* Examine each of our block's successors to see if it is | |
3881 | forwardable. */ | |
3882 | for (e = bb->succ; e; e = next) | |
3883 | { | |
3884 | next = e->succ_next; | |
3885 | ||
3886 | /* If the edge is abnormal or its destination is not | |
3887 | forwardable, then there's nothing to do. */ | |
3888 | if ((e->flags & EDGE_ABNORMAL) | |
3889 | || !tree_forwarder_block_p (e->dest)) | |
3890 | continue; | |
3891 | ||
3892 | /* Now walk through as many forwarder block as possible to | |
3893 | find the ultimate destination we want to thread our jump | |
3894 | to. */ | |
3895 | last = e->dest->succ; | |
3896 | bb_ann (e->dest)->forwardable = 0; | |
3897 | for (dest = e->dest->succ->dest; | |
3898 | tree_forwarder_block_p (dest); | |
3899 | last = dest->succ, | |
3900 | dest = dest->succ->dest) | |
3901 | { | |
3902 | /* An infinite loop detected. We redirect the edge anyway, so | |
3903 | that the loop is shrinked into single basic block. */ | |
3904 | if (!bb_ann (dest)->forwardable) | |
3905 | break; | |
3906 | ||
3907 | if (dest->succ->dest == EXIT_BLOCK_PTR) | |
3908 | break; | |
3909 | ||
3910 | bb_ann (dest)->forwardable = 0; | |
3911 | } | |
3912 | ||
3913 | /* Reset the forwardable marks to 1. */ | |
3914 | for (tmp = e->dest; | |
3915 | tmp != dest; | |
3916 | tmp = tmp->succ->dest) | |
3917 | bb_ann (tmp)->forwardable = 1; | |
3918 | ||
3919 | if (dest == e->dest) | |
3920 | continue; | |
3921 | ||
3922 | old = find_edge (bb, dest); | |
3923 | if (old) | |
3924 | { | |
3925 | /* If there already is an edge, check whether the values | |
3926 | in phi nodes differ. */ | |
3927 | if (!phi_alternatives_equal (dest, last, old)) | |
3928 | { | |
3929 | /* The previous block is forwarder. Redirect our jump | |
3930 | to that target instead since we know it has no PHI | |
3931 | nodes that will need updating. */ | |
3932 | dest = last->src; | |
3933 | ||
3934 | /* That might mean that no forwarding at all is possible. */ | |
3935 | if (dest == e->dest) | |
3936 | continue; | |
3937 | ||
3938 | old = find_edge (bb, dest); | |
3939 | } | |
3940 | } | |
3941 | ||
3942 | /* Perform the redirection. */ | |
3943 | retval = true; | |
3944 | e = redirect_edge_and_branch (e, dest); | |
3945 | ||
3946 | /* TODO -- updating dominators in this case is simple. */ | |
3947 | free_dominance_info (CDI_DOMINATORS); | |
3948 | ||
3949 | if (!old) | |
3950 | { | |
3951 | /* Update PHI nodes. We know that the new argument should | |
3952 | have the same value as the argument associated with LAST. | |
3953 | Otherwise we would have changed our target block above. */ | |
17192884 | 3954 | for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) |
6de9cd9a DN |
3955 | { |
3956 | arg = phi_arg_from_edge (phi, last); | |
3957 | if (arg < 0) | |
3958 | abort (); | |
3959 | add_phi_arg (&phi, PHI_ARG_DEF (phi, arg), e); | |
3960 | } | |
3961 | } | |
3962 | } | |
3963 | ||
3964 | /* Reset the forwardable bit on our block since it's no longer in | |
3965 | a forwarding chain path. */ | |
3966 | bb_ann (bb)->forwardable = 1; | |
3967 | } | |
3968 | ||
3969 | return retval; | |
3970 | } | |
3971 | ||
3972 | ||
3973 | /* Return a non-special label in the head of basic block BLOCK. | |
3974 | Create one if it doesn't exist. */ | |
3975 | ||
3976 | static tree | |
3977 | tree_block_label (basic_block bb) | |
3978 | { | |
3979 | block_stmt_iterator i, s = bsi_start (bb); | |
3980 | bool first = true; | |
3981 | tree label, stmt; | |
3982 | ||
3983 | for (i = s; !bsi_end_p (i); first = false, bsi_next (&i)) | |
3984 | { | |
3985 | stmt = bsi_stmt (i); | |
3986 | if (TREE_CODE (stmt) != LABEL_EXPR) | |
3987 | break; | |
3988 | label = LABEL_EXPR_LABEL (stmt); | |
3989 | if (!DECL_NONLOCAL (label)) | |
3990 | { | |
3991 | if (!first) | |
3992 | bsi_move_before (&i, &s); | |
3993 | return label; | |
3994 | } | |
3995 | } | |
3996 | ||
3997 | label = create_artificial_label (); | |
3998 | stmt = build1 (LABEL_EXPR, void_type_node, label); | |
3999 | bsi_insert_before (&s, stmt, BSI_NEW_STMT); | |
4000 | return label; | |
4001 | } | |
4002 | ||
4003 | ||
4004 | /* Attempt to perform edge redirection by replacing a possibly complex | |
4005 | jump instruction by a goto or by removing the jump completely. | |
4006 | This can apply only if all edges now point to the same block. The | |
4007 | parameters and return values are equivalent to | |
4008 | redirect_edge_and_branch. */ | |
4009 | ||
4010 | static edge | |
4011 | tree_try_redirect_by_replacing_jump (edge e, basic_block target) | |
4012 | { | |
4013 | basic_block src = e->src; | |
4014 | edge tmp; | |
4015 | block_stmt_iterator b; | |
4016 | tree stmt; | |
4017 | ||
4018 | /* Verify that all targets will be TARGET. */ | |
4019 | for (tmp = src->succ; tmp; tmp = tmp->succ_next) | |
4020 | if (tmp->dest != target && tmp != e) | |
4021 | break; | |
4022 | ||
4023 | if (tmp) | |
4024 | return NULL; | |
4025 | ||
4026 | b = bsi_last (src); | |
4027 | if (bsi_end_p (b)) | |
4028 | return NULL; | |
4029 | stmt = bsi_stmt (b); | |
4030 | ||
4031 | if (TREE_CODE (stmt) == COND_EXPR | |
4032 | || TREE_CODE (stmt) == SWITCH_EXPR) | |
4033 | { | |
4034 | bsi_remove (&b); | |
4035 | e = ssa_redirect_edge (e, target); | |
4036 | e->flags = EDGE_FALLTHRU; | |
4037 | return e; | |
4038 | } | |
4039 | ||
4040 | return NULL; | |
4041 | } | |
4042 | ||
4043 | ||
4044 | /* Redirect E to DEST. Return NULL on failure. Otherwise, return the | |
4045 | edge representing the redirected branch. */ | |
4046 | ||
4047 | static edge | |
4048 | tree_redirect_edge_and_branch (edge e, basic_block dest) | |
4049 | { | |
4050 | basic_block bb = e->src; | |
4051 | block_stmt_iterator bsi; | |
4052 | edge ret; | |
4053 | tree label, stmt; | |
4054 | ||
4055 | if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) | |
4056 | return NULL; | |
4057 | ||
4058 | if (e->src != ENTRY_BLOCK_PTR | |
4059 | && (ret = tree_try_redirect_by_replacing_jump (e, dest))) | |
4060 | return ret; | |
4061 | ||
4062 | if (e->dest == dest) | |
4063 | return NULL; | |
4064 | ||
4065 | label = tree_block_label (dest); | |
4066 | ||
4067 | bsi = bsi_last (bb); | |
4068 | stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi); | |
4069 | ||
4070 | switch (stmt ? TREE_CODE (stmt) : ERROR_MARK) | |
4071 | { | |
4072 | case COND_EXPR: | |
4073 | stmt = (e->flags & EDGE_TRUE_VALUE | |
4074 | ? COND_EXPR_THEN (stmt) | |
4075 | : COND_EXPR_ELSE (stmt)); | |
4076 | GOTO_DESTINATION (stmt) = label; | |
4077 | break; | |
4078 | ||
4079 | case GOTO_EXPR: | |
4080 | /* No non-abnormal edges should lead from a non-simple goto, and | |
4081 | simple ones should be represented implicitly. */ | |
4082 | abort (); | |
4083 | ||
4084 | case SWITCH_EXPR: | |
4085 | { | |
4086 | tree vec = SWITCH_LABELS (stmt); | |
4087 | size_t i, n = TREE_VEC_LENGTH (vec); | |
4088 | ||
4089 | for (i = 0; i < n; ++i) | |
4090 | { | |
4091 | tree elt = TREE_VEC_ELT (vec, i); | |
4092 | if (label_to_block (CASE_LABEL (elt)) == e->dest) | |
4093 | CASE_LABEL (elt) = label; | |
4094 | } | |
4095 | } | |
4096 | break; | |
4097 | ||
4098 | case RETURN_EXPR: | |
4099 | bsi_remove (&bsi); | |
4100 | e->flags |= EDGE_FALLTHRU; | |
4101 | break; | |
4102 | ||
4103 | default: | |
4104 | /* Otherwise it must be a fallthru edge, and we don't need to | |
4105 | do anything besides redirecting it. */ | |
4106 | if (!(e->flags & EDGE_FALLTHRU)) | |
4107 | abort (); | |
4108 | break; | |
4109 | } | |
4110 | ||
4111 | /* Update/insert PHI nodes as necessary. */ | |
4112 | ||
4113 | /* Now update the edges in the CFG. */ | |
4114 | e = ssa_redirect_edge (e, dest); | |
4115 | ||
4116 | return e; | |
4117 | } | |
4118 | ||
4119 | ||
4120 | /* Simple wrapper, as we can always redirect fallthru edges. */ | |
4121 | ||
4122 | static basic_block | |
4123 | tree_redirect_edge_and_branch_force (edge e, basic_block dest) | |
4124 | { | |
4125 | e = tree_redirect_edge_and_branch (e, dest); | |
4126 | if (!e) | |
4127 | abort (); | |
4128 | ||
4129 | return NULL; | |
4130 | } | |
4131 | ||
4132 | ||
4133 | /* Splits basic block BB after statement STMT (but at least after the | |
4134 | labels). If STMT is NULL, BB is split just after the labels. */ | |
4135 | ||
4136 | static basic_block | |
4137 | tree_split_block (basic_block bb, void *stmt) | |
4138 | { | |
4139 | block_stmt_iterator bsi, bsi_tgt; | |
4140 | tree act; | |
4141 | basic_block new_bb; | |
4142 | edge e; | |
4143 | ||
4144 | new_bb = create_empty_bb (bb); | |
4145 | ||
4146 | /* Redirect the outgoing edges. */ | |
4147 | new_bb->succ = bb->succ; | |
4148 | bb->succ = NULL; | |
4149 | for (e = new_bb->succ; e; e = e->succ_next) | |
4150 | e->src = new_bb; | |
4151 | ||
4152 | if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR) | |
4153 | stmt = NULL; | |
4154 | ||
4155 | /* Move everything from BSI to the new basic block. */ | |
4156 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
4157 | { | |
4158 | act = bsi_stmt (bsi); | |
4159 | if (TREE_CODE (act) == LABEL_EXPR) | |
4160 | continue; | |
4161 | ||
4162 | if (!stmt) | |
4163 | break; | |
4164 | ||
4165 | if (stmt == act) | |
4166 | { | |
4167 | bsi_next (&bsi); | |
4168 | break; | |
4169 | } | |
4170 | } | |
4171 | ||
4172 | bsi_tgt = bsi_start (new_bb); | |
4173 | while (!bsi_end_p (bsi)) | |
4174 | { | |
4175 | act = bsi_stmt (bsi); | |
4176 | bsi_remove (&bsi); | |
4177 | bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT); | |
4178 | } | |
4179 | ||
4180 | return new_bb; | |
4181 | } | |
4182 | ||
4183 | ||
4184 | /* Moves basic block BB after block AFTER. */ | |
4185 | ||
4186 | static bool | |
4187 | tree_move_block_after (basic_block bb, basic_block after) | |
4188 | { | |
4189 | if (bb->prev_bb == after) | |
4190 | return true; | |
4191 | ||
4192 | unlink_block (bb); | |
4193 | link_block (bb, after); | |
4194 | ||
4195 | return true; | |
4196 | } | |
4197 | ||
4198 | ||
4199 | /* Return true if basic_block can be duplicated. */ | |
4200 | ||
4201 | static bool | |
4202 | tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED) | |
4203 | { | |
4204 | return true; | |
4205 | } | |
4206 | ||
4207 | ||
4208 | /* Create a duplicate of the basic block BB. NOTE: This does not | |
4209 | preserve SSA form. */ | |
4210 | ||
4211 | static basic_block | |
4212 | tree_duplicate_bb (basic_block bb) | |
4213 | { | |
4214 | basic_block new_bb; | |
4215 | block_stmt_iterator bsi, bsi_tgt; | |
4216 | ||
4217 | new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb); | |
4218 | bsi_tgt = bsi_start (new_bb); | |
4219 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
4220 | { | |
4221 | tree stmt = bsi_stmt (bsi); | |
4222 | ||
4223 | if (TREE_CODE (stmt) == LABEL_EXPR) | |
4224 | continue; | |
4225 | ||
4226 | bsi_insert_after (&bsi_tgt, unshare_expr (stmt), BSI_NEW_STMT); | |
4227 | } | |
4228 | ||
4229 | return new_bb; | |
4230 | } | |
4231 | ||
4232 | ||
4233 | /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */ | |
4234 | ||
4235 | void | |
4236 | dump_function_to_file (tree fn, FILE *file, int flags) | |
4237 | { | |
4238 | tree arg, vars, var; | |
4239 | bool ignore_topmost_bind = false, any_var = false; | |
4240 | basic_block bb; | |
4241 | tree chain; | |
4242 | ||
673fda6b | 4243 | fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2)); |
6de9cd9a DN |
4244 | |
4245 | arg = DECL_ARGUMENTS (fn); | |
4246 | while (arg) | |
4247 | { | |
4248 | print_generic_expr (file, arg, dump_flags); | |
4249 | if (TREE_CHAIN (arg)) | |
4250 | fprintf (file, ", "); | |
4251 | arg = TREE_CHAIN (arg); | |
4252 | } | |
4253 | fprintf (file, ")\n"); | |
4254 | ||
4255 | if (flags & TDF_RAW) | |
4256 | { | |
4257 | dump_node (fn, TDF_SLIM | flags, file); | |
4258 | return; | |
4259 | } | |
4260 | ||
4261 | /* When GIMPLE is lowered, the variables are no longer available in | |
4262 | BIND_EXPRs, so display them separately. */ | |
4263 | if (cfun && cfun->unexpanded_var_list) | |
4264 | { | |
4265 | ignore_topmost_bind = true; | |
4266 | ||
4267 | fprintf (file, "{\n"); | |
4268 | for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars)) | |
4269 | { | |
4270 | var = TREE_VALUE (vars); | |
4271 | ||
4272 | print_generic_decl (file, var, flags); | |
4273 | fprintf (file, "\n"); | |
4274 | ||
4275 | any_var = true; | |
4276 | } | |
4277 | } | |
4278 | ||
4279 | if (basic_block_info) | |
4280 | { | |
4281 | /* Make a CFG based dump. */ | |
4282 | if (!ignore_topmost_bind) | |
4283 | fprintf (file, "{\n"); | |
4284 | ||
4285 | if (any_var && n_basic_blocks) | |
4286 | fprintf (file, "\n"); | |
4287 | ||
4288 | FOR_EACH_BB (bb) | |
4289 | dump_generic_bb (file, bb, 2, flags); | |
4290 | ||
4291 | fprintf (file, "}\n"); | |
4292 | } | |
4293 | else | |
4294 | { | |
4295 | int indent; | |
4296 | ||
4297 | /* Make a tree based dump. */ | |
4298 | chain = DECL_SAVED_TREE (fn); | |
4299 | ||
4300 | if (TREE_CODE (chain) == BIND_EXPR) | |
4301 | { | |
4302 | if (ignore_topmost_bind) | |
4303 | { | |
4304 | chain = BIND_EXPR_BODY (chain); | |
4305 | indent = 2; | |
4306 | } | |
4307 | else | |
4308 | indent = 0; | |
4309 | } | |
4310 | else | |
4311 | { | |
4312 | if (!ignore_topmost_bind) | |
4313 | fprintf (file, "{\n"); | |
4314 | indent = 2; | |
4315 | } | |
4316 | ||
4317 | if (any_var) | |
4318 | fprintf (file, "\n"); | |
4319 | ||
4320 | print_generic_stmt_indented (file, chain, flags, indent); | |
4321 | if (ignore_topmost_bind) | |
4322 | fprintf (file, "}\n"); | |
4323 | } | |
4324 | ||
4325 | fprintf (file, "\n\n"); | |
4326 | } | |
4327 | ||
4328 | ||
4329 | /* Pretty print of the loops intermediate representation. */ | |
4330 | static void print_loop (FILE *, struct loop *, int); | |
4331 | static void print_pred_bbs (FILE *, edge); | |
4332 | static void print_succ_bbs (FILE *, edge); | |
4333 | ||
4334 | ||
4335 | /* Print the predecessors indexes of edge E on FILE. */ | |
4336 | ||
4337 | static void | |
4338 | print_pred_bbs (FILE *file, edge e) | |
4339 | { | |
4340 | if (e == NULL) | |
4341 | return; | |
4342 | ||
4343 | else if (e->pred_next == NULL) | |
4344 | fprintf (file, "bb_%d", e->src->index); | |
4345 | ||
4346 | else | |
4347 | { | |
4348 | fprintf (file, "bb_%d, ", e->src->index); | |
4349 | print_pred_bbs (file, e->pred_next); | |
4350 | } | |
4351 | } | |
4352 | ||
4353 | ||
4354 | /* Print the successors indexes of edge E on FILE. */ | |
4355 | ||
4356 | static void | |
4357 | print_succ_bbs (FILE *file, edge e) | |
4358 | { | |
4359 | if (e == NULL) | |
4360 | return; | |
4361 | else if (e->succ_next == NULL) | |
4362 | fprintf (file, "bb_%d", e->dest->index); | |
4363 | else | |
4364 | { | |
4365 | fprintf (file, "bb_%d, ", e->dest->index); | |
4366 | print_succ_bbs (file, e->succ_next); | |
4367 | } | |
4368 | } | |
4369 | ||
4370 | ||
4371 | /* Pretty print LOOP on FILE, indented INDENT spaces. */ | |
4372 | ||
4373 | static void | |
4374 | print_loop (FILE *file, struct loop *loop, int indent) | |
4375 | { | |
4376 | char *s_indent; | |
4377 | basic_block bb; | |
4378 | ||
4379 | if (loop == NULL) | |
4380 | return; | |
4381 | ||
4382 | s_indent = (char *) alloca ((size_t) indent + 1); | |
4383 | memset ((void *) s_indent, ' ', (size_t) indent); | |
4384 | s_indent[indent] = '\0'; | |
4385 | ||
4386 | /* Print the loop's header. */ | |
4387 | fprintf (file, "%sloop_%d\n", s_indent, loop->num); | |
4388 | ||
4389 | /* Print the loop's body. */ | |
4390 | fprintf (file, "%s{\n", s_indent); | |
4391 | FOR_EACH_BB (bb) | |
4392 | if (bb->loop_father == loop) | |
4393 | { | |
4394 | /* Print the basic_block's header. */ | |
4395 | fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index); | |
4396 | print_pred_bbs (file, bb->pred); | |
4397 | fprintf (file, "}, succs = {"); | |
4398 | print_succ_bbs (file, bb->succ); | |
4399 | fprintf (file, "})\n"); | |
4400 | ||
4401 | /* Print the basic_block's body. */ | |
4402 | fprintf (file, "%s {\n", s_indent); | |
4403 | tree_dump_bb (bb, file, indent + 4); | |
4404 | fprintf (file, "%s }\n", s_indent); | |
4405 | } | |
4406 | ||
4407 | print_loop (file, loop->inner, indent + 2); | |
4408 | fprintf (file, "%s}\n", s_indent); | |
4409 | print_loop (file, loop->next, indent); | |
4410 | } | |
4411 | ||
4412 | ||
4413 | /* Follow a CFG edge from the entry point of the program, and on entry | |
4414 | of a loop, pretty print the loop structure on FILE. */ | |
4415 | ||
4416 | void | |
4417 | print_loop_ir (FILE *file) | |
4418 | { | |
4419 | basic_block bb; | |
4420 | ||
4421 | bb = BASIC_BLOCK (0); | |
4422 | if (bb && bb->loop_father) | |
4423 | print_loop (file, bb->loop_father, 0); | |
4424 | } | |
4425 | ||
4426 | ||
4427 | /* Debugging loops structure at tree level. */ | |
4428 | ||
4429 | void | |
4430 | debug_loop_ir (void) | |
4431 | { | |
4432 | print_loop_ir (stderr); | |
4433 | } | |
4434 | ||
4435 | ||
4436 | /* Return true if BB ends with a call, possibly followed by some | |
4437 | instructions that must stay with the call. Return false, | |
4438 | otherwise. */ | |
4439 | ||
4440 | static bool | |
4441 | tree_block_ends_with_call_p (basic_block bb) | |
4442 | { | |
4443 | block_stmt_iterator bsi = bsi_last (bb); | |
4444 | tree t = tsi_stmt (bsi.tsi); | |
4445 | ||
4446 | if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)) | |
4447 | t = TREE_OPERAND (t, 0); | |
4448 | ||
4449 | if (TREE_CODE (t) == MODIFY_EXPR) | |
4450 | t = TREE_OPERAND (t, 1); | |
4451 | ||
4452 | return TREE_CODE (t) == CALL_EXPR; | |
4453 | } | |
4454 | ||
4455 | ||
4456 | /* Return true if BB ends with a conditional branch. Return false, | |
4457 | otherwise. */ | |
4458 | ||
4459 | static bool | |
4460 | tree_block_ends_with_condjump_p (basic_block bb) | |
4461 | { | |
4462 | tree stmt = tsi_stmt (bsi_last (bb).tsi); | |
4463 | return (TREE_CODE (stmt) == COND_EXPR); | |
4464 | } | |
4465 | ||
4466 | ||
4467 | /* Return true if we need to add fake edge to exit at statement T. | |
4468 | Helper function for tree_flow_call_edges_add. */ | |
4469 | ||
4470 | static bool | |
4471 | need_fake_edge_p (tree t) | |
4472 | { | |
4473 | if (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0)) | |
4474 | t = TREE_OPERAND (t, 0); | |
4475 | ||
4476 | if (TREE_CODE (t) == MODIFY_EXPR) | |
4477 | t = TREE_OPERAND (t, 1); | |
4478 | ||
4479 | /* NORETURN and LONGJMP calls already have an edge to exit. | |
4480 | CONST, PURE and ALWAYS_RETURN calls do not need one. | |
4481 | We don't currently check for CONST and PURE here, although | |
4482 | it would be a good idea, because those attributes are | |
4483 | figured out from the RTL in mark_constant_function, and | |
4484 | the counter incrementation code from -fprofile-arcs | |
4485 | leads to different results from -fbranch-probabilities. */ | |
4486 | if (TREE_CODE (t) == CALL_EXPR | |
4487 | && !(call_expr_flags (t) & | |
4488 | (ECF_NORETURN | ECF_LONGJMP | ECF_ALWAYS_RETURN))) | |
4489 | return true; | |
4490 | ||
4491 | if (TREE_CODE (t) == ASM_EXPR | |
4492 | && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t))) | |
4493 | return true; | |
4494 | ||
4495 | return false; | |
4496 | } | |
4497 | ||
4498 | ||
4499 | /* Add fake edges to the function exit for any non constant and non | |
4500 | noreturn calls, volatile inline assembly in the bitmap of blocks | |
4501 | specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return | |
4502 | the number of blocks that were split. | |
4503 | ||
4504 | The goal is to expose cases in which entering a basic block does | |
4505 | not imply that all subsequent instructions must be executed. */ | |
4506 | ||
4507 | static int | |
4508 | tree_flow_call_edges_add (sbitmap blocks) | |
4509 | { | |
4510 | int i; | |
4511 | int blocks_split = 0; | |
4512 | int last_bb = last_basic_block; | |
4513 | bool check_last_block = false; | |
4514 | ||
4515 | if (n_basic_blocks == 0) | |
4516 | return 0; | |
4517 | ||
4518 | if (! blocks) | |
4519 | check_last_block = true; | |
4520 | else | |
4521 | check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); | |
4522 | ||
4523 | /* In the last basic block, before epilogue generation, there will be | |
4524 | a fallthru edge to EXIT. Special care is required if the last insn | |
4525 | of the last basic block is a call because make_edge folds duplicate | |
4526 | edges, which would result in the fallthru edge also being marked | |
4527 | fake, which would result in the fallthru edge being removed by | |
4528 | remove_fake_edges, which would result in an invalid CFG. | |
4529 | ||
4530 | Moreover, we can't elide the outgoing fake edge, since the block | |
4531 | profiler needs to take this into account in order to solve the minimal | |
4532 | spanning tree in the case that the call doesn't return. | |
4533 | ||
4534 | Handle this by adding a dummy instruction in a new last basic block. */ | |
4535 | if (check_last_block) | |
4536 | { | |
4537 | basic_block bb = EXIT_BLOCK_PTR->prev_bb; | |
4538 | block_stmt_iterator bsi = bsi_last (bb); | |
4539 | tree t = NULL_TREE; | |
4540 | if (!bsi_end_p (bsi)) | |
4541 | t = bsi_stmt (bsi); | |
4542 | ||
4543 | if (need_fake_edge_p (t)) | |
4544 | { | |
4545 | edge e; | |
4546 | ||
4547 | for (e = bb->succ; e; e = e->succ_next) | |
4548 | if (e->dest == EXIT_BLOCK_PTR) | |
4549 | { | |
4550 | bsi_insert_on_edge (e, build_empty_stmt ()); | |
4551 | bsi_commit_edge_inserts ((int *)NULL); | |
4552 | break; | |
4553 | } | |
4554 | } | |
4555 | } | |
4556 | ||
4557 | /* Now add fake edges to the function exit for any non constant | |
4558 | calls since there is no way that we can determine if they will | |
4559 | return or not... */ | |
4560 | for (i = 0; i < last_bb; i++) | |
4561 | { | |
4562 | basic_block bb = BASIC_BLOCK (i); | |
4563 | block_stmt_iterator bsi; | |
4564 | tree stmt, last_stmt; | |
4565 | ||
4566 | if (!bb) | |
4567 | continue; | |
4568 | ||
4569 | if (blocks && !TEST_BIT (blocks, i)) | |
4570 | continue; | |
4571 | ||
4572 | bsi = bsi_last (bb); | |
4573 | if (!bsi_end_p (bsi)) | |
4574 | { | |
4575 | last_stmt = bsi_stmt (bsi); | |
4576 | do | |
4577 | { | |
4578 | stmt = bsi_stmt (bsi); | |
4579 | if (need_fake_edge_p (stmt)) | |
4580 | { | |
4581 | edge e; | |
4582 | /* The handling above of the final block before the | |
4583 | epilogue should be enough to verify that there is | |
4584 | no edge to the exit block in CFG already. | |
4585 | Calling make_edge in such case would cause us to | |
4586 | mark that edge as fake and remove it later. */ | |
4587 | #ifdef ENABLE_CHECKING | |
4588 | if (stmt == last_stmt) | |
4589 | for (e = bb->succ; e; e = e->succ_next) | |
4590 | if (e->dest == EXIT_BLOCK_PTR) | |
4591 | abort (); | |
4592 | #endif | |
4593 | ||
4594 | /* Note that the following may create a new basic block | |
4595 | and renumber the existing basic blocks. */ | |
4596 | if (stmt != last_stmt) | |
4597 | { | |
4598 | e = split_block (bb, stmt); | |
4599 | if (e) | |
4600 | blocks_split++; | |
4601 | } | |
4602 | make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); | |
4603 | } | |
4604 | bsi_prev (&bsi); | |
4605 | } | |
4606 | while (!bsi_end_p (bsi)); | |
4607 | } | |
4608 | } | |
4609 | ||
4610 | if (blocks_split) | |
4611 | verify_flow_info (); | |
4612 | ||
4613 | return blocks_split; | |
4614 | } | |
4615 | ||
4616 | ||
4617 | struct cfg_hooks tree_cfg_hooks = { | |
4618 | "tree", | |
4619 | tree_verify_flow_info, | |
4620 | tree_dump_bb, /* dump_bb */ | |
4621 | create_bb, /* create_basic_block */ | |
4622 | tree_redirect_edge_and_branch,/* redirect_edge_and_branch */ | |
4623 | tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */ | |
4624 | remove_bb, /* delete_basic_block */ | |
4625 | tree_split_block, /* split_block */ | |
4626 | tree_move_block_after, /* move_block_after */ | |
4627 | tree_can_merge_blocks_p, /* can_merge_blocks_p */ | |
4628 | tree_merge_blocks, /* merge_blocks */ | |
4629 | tree_predict_edge, /* predict_edge */ | |
4630 | tree_predicted_by_p, /* predicted_by_p */ | |
4631 | tree_can_duplicate_bb_p, /* can_duplicate_block_p */ | |
4632 | tree_duplicate_bb, /* duplicate_block */ | |
4633 | tree_split_edge, /* split_edge */ | |
4634 | tree_make_forwarder_block, /* make_forward_block */ | |
4635 | NULL, /* tidy_fallthru_edge */ | |
4636 | tree_block_ends_with_call_p, /* block_ends_with_call_p */ | |
4637 | tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */ | |
4638 | tree_flow_call_edges_add /* flow_call_edges_add */ | |
4639 | }; | |
4640 | ||
4641 | ||
4642 | /* Split all critical edges. */ | |
4643 | ||
4644 | static void | |
4645 | split_critical_edges (void) | |
4646 | { | |
4647 | basic_block bb; | |
4648 | edge e; | |
4649 | ||
4650 | FOR_ALL_BB (bb) | |
4651 | { | |
4652 | for (e = bb->succ; e ; e = e->succ_next) | |
4653 | if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL)) | |
4654 | { | |
4655 | split_edge (e); | |
4656 | } | |
4657 | } | |
4658 | } | |
4659 | ||
4660 | struct tree_opt_pass pass_split_crit_edges = | |
4661 | { | |
5d44aeed | 4662 | "crited", /* name */ |
6de9cd9a DN |
4663 | NULL, /* gate */ |
4664 | split_critical_edges, /* execute */ | |
4665 | NULL, /* sub */ | |
4666 | NULL, /* next */ | |
4667 | 0, /* static_pass_number */ | |
4668 | TV_TREE_SPLIT_EDGES, /* tv_id */ | |
4669 | PROP_cfg, /* properties required */ | |
4670 | PROP_no_crit_edges, /* properties_provided */ | |
4671 | 0, /* properties_destroyed */ | |
4672 | 0, /* todo_flags_start */ | |
5d44aeed | 4673 | TODO_dump_func, /* todo_flags_finish */ |
6de9cd9a DN |
4674 | }; |
4675 | \f | |
4676 | /* Emit return warnings. */ | |
4677 | ||
4678 | static void | |
4679 | execute_warn_function_return (void) | |
4680 | { | |
4681 | location_t *locus; | |
4682 | tree last; | |
4683 | edge e; | |
4684 | ||
4685 | if (warn_missing_noreturn | |
4686 | && !TREE_THIS_VOLATILE (cfun->decl) | |
4687 | && EXIT_BLOCK_PTR->pred == NULL | |
4688 | && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl)) | |
4689 | warning ("%Jfunction might be possible candidate for attribute `noreturn'", | |
4690 | cfun->decl); | |
4691 | ||
4692 | /* If we have a path to EXIT, then we do return. */ | |
4693 | if (TREE_THIS_VOLATILE (cfun->decl) | |
4694 | && EXIT_BLOCK_PTR->pred != NULL) | |
4695 | { | |
4696 | locus = NULL; | |
4697 | for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next) | |
4698 | { | |
4699 | last = last_stmt (e->src); | |
4700 | if (TREE_CODE (last) == RETURN_EXPR | |
4701 | && (locus = EXPR_LOCUS (last)) != NULL) | |
4702 | break; | |
4703 | } | |
4704 | if (!locus) | |
4705 | locus = &cfun->function_end_locus; | |
4706 | warning ("%H`noreturn' function does return", locus); | |
4707 | } | |
4708 | ||
4709 | /* If we see "return;" in some basic block, then we do reach the end | |
4710 | without returning a value. */ | |
4711 | else if (warn_return_type | |
4712 | && EXIT_BLOCK_PTR->pred != NULL | |
4713 | && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl)))) | |
4714 | { | |
4715 | for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next) | |
4716 | { | |
4717 | tree last = last_stmt (e->src); | |
4718 | if (TREE_CODE (last) == RETURN_EXPR | |
4719 | && TREE_OPERAND (last, 0) == NULL) | |
4720 | { | |
4721 | locus = EXPR_LOCUS (last); | |
4722 | if (!locus) | |
4723 | locus = &cfun->function_end_locus; | |
4724 | warning ("%Hcontrol reaches end of non-void function", locus); | |
4725 | break; | |
4726 | } | |
4727 | } | |
4728 | } | |
4729 | } | |
4730 | ||
4731 | ||
4732 | /* Given a basic block B which ends with a conditional and has | |
4733 | precisely two successors, determine which of the edges is taken if | |
4734 | the conditional is true and which is taken if the conditional is | |
4735 | false. Set TRUE_EDGE and FALSE_EDGE appropriately. */ | |
4736 | ||
4737 | void | |
4738 | extract_true_false_edges_from_block (basic_block b, | |
4739 | edge *true_edge, | |
4740 | edge *false_edge) | |
4741 | { | |
4742 | edge e = b->succ; | |
4743 | ||
4744 | if (e->flags & EDGE_TRUE_VALUE) | |
4745 | { | |
4746 | *true_edge = e; | |
4747 | *false_edge = e->succ_next; | |
4748 | } | |
4749 | else | |
4750 | { | |
4751 | *false_edge = e; | |
4752 | *true_edge = e->succ_next; | |
4753 | } | |
4754 | } | |
4755 | ||
4756 | struct tree_opt_pass pass_warn_function_return = | |
4757 | { | |
4758 | NULL, /* name */ | |
4759 | NULL, /* gate */ | |
4760 | execute_warn_function_return, /* execute */ | |
4761 | NULL, /* sub */ | |
4762 | NULL, /* next */ | |
4763 | 0, /* static_pass_number */ | |
4764 | 0, /* tv_id */ | |
4765 | PROP_ssa, /* properties_required */ | |
4766 | 0, /* properties_provided */ | |
4767 | 0, /* properties_destroyed */ | |
4768 | 0, /* todo_flags_start */ | |
4769 | 0 /* todo_flags_finish */ | |
4770 | }; | |
4771 | ||
4772 | #include "gt-tree-cfg.h" |