Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-loop-ch.c @ 127:4c56639505ff
fix function.c and add CbC-example Makefile
author | mir3636 |
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date | Wed, 11 Apr 2018 18:46:58 +0900 |
parents | 04ced10e8804 |
children | 84e7813d76e9 |
rev | line source |
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0 | 1 /* Loop header copying on trees. |
111 | 2 Copyright (C) 2004-2017 Free Software Foundation, Inc. |
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3 |
0 | 4 This file is part of GCC. |
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5 |
0 | 6 GCC is free software; you can redistribute it and/or modify it |
7 under the terms of the GNU General Public License as published by the | |
8 Free Software Foundation; either version 3, or (at your option) any | |
9 later version. | |
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10 |
0 | 11 GCC is distributed in the hope that it will be useful, but WITHOUT |
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 for more details. | |
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15 |
0 | 16 You should have received a copy of the GNU General Public License |
17 along with GCC; see the file COPYING3. If not see | |
18 <http://www.gnu.org/licenses/>. */ | |
19 | |
20 #include "config.h" | |
21 #include "system.h" | |
22 #include "coretypes.h" | |
111 | 23 #include "backend.h" |
0 | 24 #include "tree.h" |
111 | 25 #include "gimple.h" |
26 #include "cfghooks.h" | |
0 | 27 #include "tree-pass.h" |
111 | 28 #include "gimple-ssa.h" |
29 #include "gimple-iterator.h" | |
30 #include "tree-cfg.h" | |
31 #include "tree-into-ssa.h" | |
0 | 32 #include "cfgloop.h" |
33 #include "tree-inline.h" | |
111 | 34 #include "tree-ssa-scopedtables.h" |
35 #include "tree-ssa-threadedge.h" | |
36 #include "params.h" | |
0 | 37 |
38 /* Duplicates headers of loops if they are small enough, so that the statements | |
39 in the loop body are always executed when the loop is entered. This | |
40 increases effectiveness of code motion optimizations, and reduces the need | |
41 for loop preconditioning. */ | |
42 | |
43 /* Check whether we should duplicate HEADER of LOOP. At most *LIMIT | |
44 instructions should be duplicated, limit is decreased by the actual | |
45 amount. */ | |
46 | |
47 static bool | |
48 should_duplicate_loop_header_p (basic_block header, struct loop *loop, | |
49 int *limit) | |
50 { | |
51 gimple_stmt_iterator bsi; | |
111 | 52 gimple *last; |
0 | 53 |
111 | 54 gcc_assert (!header->aux); |
0 | 55 |
56 /* Loop header copying usually increases size of the code. This used not to | |
57 be true, since quite often it is possible to verify that the condition is | |
58 satisfied in the first iteration and therefore to eliminate it. Jump | |
59 threading handles these cases now. */ | |
60 if (optimize_loop_for_size_p (loop)) | |
111 | 61 { |
62 if (dump_file && (dump_flags & TDF_DETAILS)) | |
63 fprintf (dump_file, | |
64 " Not duplicating bb %i: optimizing for size.\n", | |
65 header->index); | |
66 return false; | |
67 } | |
0 | 68 |
69 gcc_assert (EDGE_COUNT (header->succs) > 0); | |
70 if (single_succ_p (header)) | |
111 | 71 { |
72 if (dump_file && (dump_flags & TDF_DETAILS)) | |
73 fprintf (dump_file, | |
74 " Not duplicating bb %i: it is single succ.\n", | |
75 header->index); | |
76 return false; | |
77 } | |
78 | |
0 | 79 if (flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 0)->dest) |
80 && flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 1)->dest)) | |
111 | 81 { |
82 if (dump_file && (dump_flags & TDF_DETAILS)) | |
83 fprintf (dump_file, | |
84 " Not duplicating bb %i: both sucessors are in loop.\n", | |
85 loop->num); | |
86 return false; | |
87 } | |
0 | 88 |
89 /* If this is not the original loop header, we want it to have just | |
90 one predecessor in order to match the && pattern. */ | |
91 if (header != loop->header && !single_pred_p (header)) | |
111 | 92 { |
93 if (dump_file && (dump_flags & TDF_DETAILS)) | |
94 fprintf (dump_file, | |
95 " Not duplicating bb %i: it has mutiple predecestors.\n", | |
96 header->index); | |
97 return false; | |
98 } | |
0 | 99 |
100 last = last_stmt (header); | |
101 if (gimple_code (last) != GIMPLE_COND) | |
111 | 102 { |
103 if (dump_file && (dump_flags & TDF_DETAILS)) | |
104 fprintf (dump_file, | |
105 " Not duplicating bb %i: it does not end by conditional.\n", | |
106 header->index); | |
107 return false; | |
108 } | |
0 | 109 |
111 | 110 /* Count number of instructions and punt on calls. */ |
0 | 111 for (bsi = gsi_start_bb (header); !gsi_end_p (bsi); gsi_next (&bsi)) |
112 { | |
113 last = gsi_stmt (bsi); | |
114 | |
115 if (gimple_code (last) == GIMPLE_LABEL) | |
116 continue; | |
117 | |
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118 if (is_gimple_debug (last)) |
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119 continue; |
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120 |
111 | 121 if (gimple_code (last) == GIMPLE_CALL |
122 && (!gimple_inexpensive_call_p (as_a <gcall *> (last)) | |
123 /* IFN_LOOP_DIST_ALIAS means that inner loop is distributed | |
124 at current loop's header. Don't copy in this case. */ | |
125 || gimple_call_internal_p (last, IFN_LOOP_DIST_ALIAS))) | |
126 { | |
127 if (dump_file && (dump_flags & TDF_DETAILS)) | |
128 fprintf (dump_file, | |
129 " Not duplicating bb %i: it contains call.\n", | |
130 header->index); | |
131 return false; | |
132 } | |
0 | 133 |
134 *limit -= estimate_num_insns (last, &eni_size_weights); | |
135 if (*limit < 0) | |
111 | 136 { |
137 if (dump_file && (dump_flags & TDF_DETAILS)) | |
138 fprintf (dump_file, | |
139 " Not duplicating bb %i contains too many insns.\n", | |
140 header->index); | |
141 return false; | |
142 } | |
0 | 143 } |
111 | 144 if (dump_file && (dump_flags & TDF_DETAILS)) |
145 fprintf (dump_file, " Will duplicate bb %i\n", header->index); | |
0 | 146 return true; |
147 } | |
148 | |
149 /* Checks whether LOOP is a do-while style loop. */ | |
150 | |
151 static bool | |
152 do_while_loop_p (struct loop *loop) | |
153 { | |
111 | 154 gimple *stmt = last_stmt (loop->latch); |
0 | 155 |
156 /* If the latch of the loop is not empty, it is not a do-while loop. */ | |
157 if (stmt | |
158 && gimple_code (stmt) != GIMPLE_LABEL) | |
111 | 159 { |
160 if (dump_file && (dump_flags & TDF_DETAILS)) | |
161 fprintf (dump_file, | |
162 "Loop %i is not do-while loop: latch is not empty.\n", | |
163 loop->num); | |
164 return false; | |
165 } | |
0 | 166 |
167 /* If the header contains just a condition, it is not a do-while loop. */ | |
168 stmt = last_and_only_stmt (loop->header); | |
169 if (stmt | |
170 && gimple_code (stmt) == GIMPLE_COND) | |
111 | 171 { |
172 if (dump_file && (dump_flags & TDF_DETAILS)) | |
173 fprintf (dump_file, | |
174 "Loop %i is not do-while loop: " | |
175 "header contains just condition.\n", loop->num); | |
176 return false; | |
177 } | |
178 if (dump_file && (dump_flags & TDF_DETAILS)) | |
179 fprintf (dump_file, "Loop %i is do-while loop\n", loop->num); | |
0 | 180 |
181 return true; | |
182 } | |
183 | |
111 | 184 namespace { |
185 | |
186 /* Common superclass for both header-copying phases. */ | |
187 class ch_base : public gimple_opt_pass | |
188 { | |
189 protected: | |
190 ch_base (pass_data data, gcc::context *ctxt) | |
191 : gimple_opt_pass (data, ctxt) | |
192 {} | |
193 | |
194 /* Copies headers of all loops in FUN for which process_loop_p is true. */ | |
195 unsigned int copy_headers (function *fun); | |
196 | |
197 /* Return true to copy headers of LOOP or false to skip. */ | |
198 virtual bool process_loop_p (struct loop *loop) = 0; | |
199 }; | |
200 | |
201 const pass_data pass_data_ch = | |
202 { | |
203 GIMPLE_PASS, /* type */ | |
204 "ch", /* name */ | |
205 OPTGROUP_LOOP, /* optinfo_flags */ | |
206 TV_TREE_CH, /* tv_id */ | |
207 ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
208 0, /* properties_provided */ | |
209 0, /* properties_destroyed */ | |
210 0, /* todo_flags_start */ | |
211 0, /* todo_flags_finish */ | |
212 }; | |
213 | |
214 class pass_ch : public ch_base | |
215 { | |
216 public: | |
217 pass_ch (gcc::context *ctxt) | |
218 : ch_base (pass_data_ch, ctxt) | |
219 {} | |
220 | |
221 /* opt_pass methods: */ | |
222 virtual bool gate (function *) { return flag_tree_ch != 0; } | |
223 | |
224 /* Initialize and finalize loop structures, copying headers inbetween. */ | |
225 virtual unsigned int execute (function *); | |
226 | |
227 opt_pass * clone () { return new pass_ch (m_ctxt); } | |
228 | |
229 protected: | |
230 /* ch_base method: */ | |
231 virtual bool process_loop_p (struct loop *loop); | |
232 }; // class pass_ch | |
233 | |
234 const pass_data pass_data_ch_vect = | |
235 { | |
236 GIMPLE_PASS, /* type */ | |
237 "ch_vect", /* name */ | |
238 OPTGROUP_LOOP, /* optinfo_flags */ | |
239 TV_TREE_CH, /* tv_id */ | |
240 ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
241 0, /* properties_provided */ | |
242 0, /* properties_destroyed */ | |
243 0, /* todo_flags_start */ | |
244 0, /* todo_flags_finish */ | |
245 }; | |
246 | |
247 /* This is a more aggressive version of the same pass, designed to run just | |
248 before if-conversion and vectorization, to put more loops into the form | |
249 required for those phases. */ | |
250 class pass_ch_vect : public ch_base | |
251 { | |
252 public: | |
253 pass_ch_vect (gcc::context *ctxt) | |
254 : ch_base (pass_data_ch_vect, ctxt) | |
255 {} | |
256 | |
257 /* opt_pass methods: */ | |
258 virtual bool gate (function *fun) | |
259 { | |
260 return flag_tree_ch != 0 | |
261 && (flag_tree_loop_vectorize != 0 || fun->has_force_vectorize_loops); | |
262 } | |
263 | |
264 /* Just copy headers, no initialization/finalization of loop structures. */ | |
265 virtual unsigned int execute (function *); | |
266 | |
267 protected: | |
268 /* ch_base method: */ | |
269 virtual bool process_loop_p (struct loop *loop); | |
270 }; // class pass_ch_vect | |
271 | |
0 | 272 /* For all loops, copy the condition at the end of the loop body in front |
273 of the loop. This is beneficial since it increases efficiency of | |
274 code motion optimizations. It also saves one jump on entry to the loop. */ | |
275 | |
111 | 276 unsigned int |
277 ch_base::copy_headers (function *fun) | |
0 | 278 { |
279 struct loop *loop; | |
280 basic_block header; | |
281 edge exit, entry; | |
282 basic_block *bbs, *copied_bbs; | |
283 unsigned n_bbs; | |
284 unsigned bbs_size; | |
111 | 285 bool changed = false; |
0 | 286 |
111 | 287 if (number_of_loops (fun) <= 1) |
0 | 288 return 0; |
289 | |
111 | 290 bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (fun)); |
291 copied_bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (fun)); | |
292 bbs_size = n_basic_blocks_for_fn (fun); | |
0 | 293 |
111 | 294 FOR_EACH_LOOP (loop, 0) |
0 | 295 { |
111 | 296 int initial_limit = PARAM_VALUE (PARAM_MAX_LOOP_HEADER_INSNS); |
297 int remaining_limit = initial_limit; | |
298 if (dump_file && (dump_flags & TDF_DETAILS)) | |
299 fprintf (dump_file, | |
300 "Analyzing loop %i\n", loop->num); | |
0 | 301 |
302 header = loop->header; | |
303 | |
304 /* If the loop is already a do-while style one (either because it was | |
305 written as such, or because jump threading transformed it into one), | |
306 we might be in fact peeling the first iteration of the loop. This | |
307 in general is not a good idea. */ | |
111 | 308 if (!process_loop_p (loop)) |
0 | 309 continue; |
310 | |
311 /* Iterate the header copying up to limit; this takes care of the cases | |
312 like while (a && b) {...}, where we want to have both of the conditions | |
313 copied. TODO -- handle while (a || b) - like cases, by not requiring | |
314 the header to have just a single successor and copying up to | |
315 postdominator. */ | |
316 | |
317 exit = NULL; | |
318 n_bbs = 0; | |
111 | 319 while (should_duplicate_loop_header_p (header, loop, &remaining_limit)) |
0 | 320 { |
321 /* Find a successor of header that is inside a loop; i.e. the new | |
322 header after the condition is copied. */ | |
323 if (flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 0)->dest)) | |
324 exit = EDGE_SUCC (header, 0); | |
325 else | |
326 exit = EDGE_SUCC (header, 1); | |
327 bbs[n_bbs++] = header; | |
328 gcc_assert (bbs_size > n_bbs); | |
329 header = exit->dest; | |
330 } | |
331 | |
332 if (!exit) | |
333 continue; | |
334 | |
335 if (dump_file && (dump_flags & TDF_DETAILS)) | |
336 fprintf (dump_file, | |
111 | 337 "Duplicating header of the loop %d up to edge %d->%d," |
338 " %i insns.\n", | |
339 loop->num, exit->src->index, exit->dest->index, | |
340 initial_limit - remaining_limit); | |
0 | 341 |
342 /* Ensure that the header will have just the latch as a predecessor | |
343 inside the loop. */ | |
344 if (!single_pred_p (exit->dest)) | |
345 exit = single_pred_edge (split_edge (exit)); | |
346 | |
347 entry = loop_preheader_edge (loop); | |
348 | |
111 | 349 propagate_threaded_block_debug_into (exit->dest, entry->dest); |
350 if (!gimple_duplicate_sese_region (entry, exit, bbs, n_bbs, copied_bbs, | |
351 true)) | |
0 | 352 { |
353 fprintf (dump_file, "Duplication failed.\n"); | |
354 continue; | |
355 } | |
356 | |
357 /* If the loop has the form "for (i = j; i < j + 10; i++)" then | |
358 this copying can introduce a case where we rely on undefined | |
359 signed overflow to eliminate the preheader condition, because | |
360 we assume that "j < j + 10" is true. We don't want to warn | |
361 about that case for -Wstrict-overflow, because in general we | |
362 don't warn about overflow involving loops. Prevent the | |
363 warning by setting the no_warning flag in the condition. */ | |
364 if (warn_strict_overflow > 0) | |
365 { | |
366 unsigned int i; | |
367 | |
368 for (i = 0; i < n_bbs; ++i) | |
369 { | |
370 gimple_stmt_iterator bsi; | |
371 | |
372 for (bsi = gsi_start_bb (copied_bbs[i]); | |
373 !gsi_end_p (bsi); | |
374 gsi_next (&bsi)) | |
375 { | |
111 | 376 gimple *stmt = gsi_stmt (bsi); |
0 | 377 if (gimple_code (stmt) == GIMPLE_COND) |
378 gimple_set_no_warning (stmt, true); | |
379 else if (is_gimple_assign (stmt)) | |
380 { | |
381 enum tree_code rhs_code = gimple_assign_rhs_code (stmt); | |
382 if (TREE_CODE_CLASS (rhs_code) == tcc_comparison) | |
383 gimple_set_no_warning (stmt, true); | |
384 } | |
385 } | |
386 } | |
387 } | |
388 | |
389 /* Ensure that the latch and the preheader is simple (we know that they | |
390 are not now, since there was the loop exit condition. */ | |
391 split_edge (loop_preheader_edge (loop)); | |
392 split_edge (loop_latch_edge (loop)); | |
111 | 393 |
394 changed = true; | |
0 | 395 } |
396 | |
111 | 397 if (changed) |
398 update_ssa (TODO_update_ssa); | |
0 | 399 free (bbs); |
400 free (copied_bbs); | |
401 | |
111 | 402 return changed ? TODO_cleanup_cfg : 0; |
403 } | |
404 | |
405 /* Initialize the loop structures we need, and finalize after. */ | |
406 | |
407 unsigned int | |
408 pass_ch::execute (function *fun) | |
409 { | |
410 loop_optimizer_init (LOOPS_HAVE_PREHEADERS | |
411 | LOOPS_HAVE_SIMPLE_LATCHES); | |
412 | |
413 unsigned int res = copy_headers (fun); | |
414 | |
0 | 415 loop_optimizer_finalize (); |
111 | 416 return res; |
0 | 417 } |
418 | |
111 | 419 /* Assume an earlier phase has already initialized all the loop structures that |
420 we need here (and perhaps others too), and that these will be finalized by | |
421 a later phase. */ | |
422 | |
423 unsigned int | |
424 pass_ch_vect::execute (function *fun) | |
0 | 425 { |
111 | 426 return copy_headers (fun); |
427 } | |
428 | |
429 /* Apply header copying according to a very simple test of do-while shape. */ | |
430 | |
431 bool | |
432 pass_ch::process_loop_p (struct loop *loop) | |
433 { | |
434 return !do_while_loop_p (loop); | |
0 | 435 } |
436 | |
111 | 437 /* Apply header-copying to loops where we might enable vectorization. */ |
438 | |
439 bool | |
440 pass_ch_vect::process_loop_p (struct loop *loop) | |
0 | 441 { |
111 | 442 if (!flag_tree_loop_vectorize && !loop->force_vectorize) |
443 return false; | |
444 | |
445 if (loop->dont_vectorize) | |
446 return false; | |
447 | |
448 if (!do_while_loop_p (loop)) | |
449 return true; | |
450 | |
451 /* The vectorizer won't handle anything with multiple exits, so skip. */ | |
452 edge exit = single_exit (loop); | |
453 if (!exit) | |
454 return false; | |
455 | |
456 /* Copy headers iff there looks to be code in the loop after the exit block, | |
457 i.e. the exit block has an edge to another block (besides the latch, | |
458 which should be empty). */ | |
459 edge_iterator ei; | |
460 edge e; | |
461 FOR_EACH_EDGE (e, ei, exit->src->succs) | |
462 if (!loop_exit_edge_p (loop, e) | |
463 && e->dest != loop->header | |
464 && e->dest != loop->latch) | |
465 return true; | |
466 | |
467 return false; | |
468 } | |
469 | |
470 } // anon namespace | |
471 | |
472 gimple_opt_pass * | |
473 make_pass_ch_vect (gcc::context *ctxt) | |
474 { | |
475 return new pass_ch_vect (ctxt); | |
476 } | |
477 | |
478 gimple_opt_pass * | |
479 make_pass_ch (gcc::context *ctxt) | |
480 { | |
481 return new pass_ch (ctxt); | |
482 } |