|
0
|
1 /* Optimization of PHI nodes by converting them into straightline code.
|
|
|
2 Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation,
|
|
|
3 Inc.
|
|
|
4
|
|
|
5 This file is part of GCC.
|
|
|
6
|
|
|
7 GCC is free software; you can redistribute it and/or modify it
|
|
|
8 under the terms of the GNU General Public License as published by the
|
|
|
9 Free Software Foundation; either version 3, or (at your option) any
|
|
|
10 later version.
|
|
|
11
|
|
|
12 GCC is distributed in the hope that it will be useful, but WITHOUT
|
|
|
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
|
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
|
15 for more details.
|
|
|
16
|
|
|
17 You should have received a copy of the GNU General Public License
|
|
|
18 along with GCC; see the file COPYING3. If not see
|
|
|
19 <http://www.gnu.org/licenses/>. */
|
|
|
20
|
|
|
21 #include "config.h"
|
|
|
22 #include "system.h"
|
|
|
23 #include "coretypes.h"
|
|
|
24 #include "tm.h"
|
|
|
25 #include "ggc.h"
|
|
|
26 #include "tree.h"
|
|
|
27 #include "rtl.h"
|
|
|
28 #include "flags.h"
|
|
|
29 #include "tm_p.h"
|
|
|
30 #include "basic-block.h"
|
|
|
31 #include "timevar.h"
|
|
|
32 #include "diagnostic.h"
|
|
|
33 #include "tree-flow.h"
|
|
|
34 #include "tree-pass.h"
|
|
|
35 #include "tree-dump.h"
|
|
|
36 #include "langhooks.h"
|
|
|
37 #include "pointer-set.h"
|
|
|
38 #include "domwalk.h"
|
|
|
39
|
|
|
40 static unsigned int tree_ssa_phiopt (void);
|
|
|
41 static unsigned int tree_ssa_phiopt_worker (bool);
|
|
|
42 static bool conditional_replacement (basic_block, basic_block,
|
|
|
43 edge, edge, gimple, tree, tree);
|
|
|
44 static bool value_replacement (basic_block, basic_block,
|
|
|
45 edge, edge, gimple, tree, tree);
|
|
|
46 static bool minmax_replacement (basic_block, basic_block,
|
|
|
47 edge, edge, gimple, tree, tree);
|
|
|
48 static bool abs_replacement (basic_block, basic_block,
|
|
|
49 edge, edge, gimple, tree, tree);
|
|
|
50 static bool cond_store_replacement (basic_block, basic_block, edge, edge,
|
|
|
51 struct pointer_set_t *);
|
|
|
52 static struct pointer_set_t * get_non_trapping (void);
|
|
|
53 static void replace_phi_edge_with_variable (basic_block, edge, gimple, tree);
|
|
|
54
|
|
|
55 /* This pass tries to replaces an if-then-else block with an
|
|
|
56 assignment. We have four kinds of transformations. Some of these
|
|
|
57 transformations are also performed by the ifcvt RTL optimizer.
|
|
|
58
|
|
|
59 Conditional Replacement
|
|
|
60 -----------------------
|
|
|
61
|
|
|
62 This transformation, implemented in conditional_replacement,
|
|
|
63 replaces
|
|
|
64
|
|
|
65 bb0:
|
|
|
66 if (cond) goto bb2; else goto bb1;
|
|
|
67 bb1:
|
|
|
68 bb2:
|
|
|
69 x = PHI <0 (bb1), 1 (bb0), ...>;
|
|
|
70
|
|
|
71 with
|
|
|
72
|
|
|
73 bb0:
|
|
|
74 x' = cond;
|
|
|
75 goto bb2;
|
|
|
76 bb2:
|
|
|
77 x = PHI <x' (bb0), ...>;
|
|
|
78
|
|
|
79 We remove bb1 as it becomes unreachable. This occurs often due to
|
|
|
80 gimplification of conditionals.
|
|
|
81
|
|
|
82 Value Replacement
|
|
|
83 -----------------
|
|
|
84
|
|
|
85 This transformation, implemented in value_replacement, replaces
|
|
|
86
|
|
|
87 bb0:
|
|
|
88 if (a != b) goto bb2; else goto bb1;
|
|
|
89 bb1:
|
|
|
90 bb2:
|
|
|
91 x = PHI <a (bb1), b (bb0), ...>;
|
|
|
92
|
|
|
93 with
|
|
|
94
|
|
|
95 bb0:
|
|
|
96 bb2:
|
|
|
97 x = PHI <b (bb0), ...>;
|
|
|
98
|
|
|
99 This opportunity can sometimes occur as a result of other
|
|
|
100 optimizations.
|
|
|
101
|
|
|
102 ABS Replacement
|
|
|
103 ---------------
|
|
|
104
|
|
|
105 This transformation, implemented in abs_replacement, replaces
|
|
|
106
|
|
|
107 bb0:
|
|
|
108 if (a >= 0) goto bb2; else goto bb1;
|
|
|
109 bb1:
|
|
|
110 x = -a;
|
|
|
111 bb2:
|
|
|
112 x = PHI <x (bb1), a (bb0), ...>;
|
|
|
113
|
|
|
114 with
|
|
|
115
|
|
|
116 bb0:
|
|
|
117 x' = ABS_EXPR< a >;
|
|
|
118 bb2:
|
|
|
119 x = PHI <x' (bb0), ...>;
|
|
|
120
|
|
|
121 MIN/MAX Replacement
|
|
|
122 -------------------
|
|
|
123
|
|
|
124 This transformation, minmax_replacement replaces
|
|
|
125
|
|
|
126 bb0:
|
|
|
127 if (a <= b) goto bb2; else goto bb1;
|
|
|
128 bb1:
|
|
|
129 bb2:
|
|
|
130 x = PHI <b (bb1), a (bb0), ...>;
|
|
|
131
|
|
|
132 with
|
|
|
133
|
|
|
134 bb0:
|
|
|
135 x' = MIN_EXPR (a, b)
|
|
|
136 bb2:
|
|
|
137 x = PHI <x' (bb0), ...>;
|
|
|
138
|
|
|
139 A similar transformation is done for MAX_EXPR. */
|
|
|
140
|
|
|
141 static unsigned int
|
|
|
142 tree_ssa_phiopt (void)
|
|
|
143 {
|
|
|
144 return tree_ssa_phiopt_worker (false);
|
|
|
145 }
|
|
|
146
|
|
|
147 /* This pass tries to transform conditional stores into unconditional
|
|
|
148 ones, enabling further simplifications with the simpler then and else
|
|
|
149 blocks. In particular it replaces this:
|
|
|
150
|
|
|
151 bb0:
|
|
|
152 if (cond) goto bb2; else goto bb1;
|
|
|
153 bb1:
|
|
|
154 *p = RHS
|
|
|
155 bb2:
|
|
|
156
|
|
|
157 with
|
|
|
158
|
|
|
159 bb0:
|
|
|
160 if (cond) goto bb1; else goto bb2;
|
|
|
161 bb1:
|
|
|
162 condtmp' = *p;
|
|
|
163 bb2:
|
|
|
164 condtmp = PHI <RHS, condtmp'>
|
|
|
165 *p = condtmp
|
|
|
166
|
|
|
167 This transformation can only be done under several constraints,
|
|
|
168 documented below. */
|
|
|
169
|
|
|
170 static unsigned int
|
|
|
171 tree_ssa_cs_elim (void)
|
|
|
172 {
|
|
|
173 return tree_ssa_phiopt_worker (true);
|
|
|
174 }
|
|
|
175
|
|
|
176 /* For conditional store replacement we need a temporary to
|
|
|
177 put the old contents of the memory in. */
|
|
|
178 static tree condstoretemp;
|
|
|
179
|
|
|
180 /* The core routine of conditional store replacement and normal
|
|
|
181 phi optimizations. Both share much of the infrastructure in how
|
|
|
182 to match applicable basic block patterns. DO_STORE_ELIM is true
|
|
|
183 when we want to do conditional store replacement, false otherwise. */
|
|
|
184 static unsigned int
|
|
|
185 tree_ssa_phiopt_worker (bool do_store_elim)
|
|
|
186 {
|
|
|
187 basic_block bb;
|
|
|
188 basic_block *bb_order;
|
|
|
189 unsigned n, i;
|
|
|
190 bool cfgchanged = false;
|
|
|
191 struct pointer_set_t *nontrap = 0;
|
|
|
192
|
|
|
193 if (do_store_elim)
|
|
|
194 {
|
|
|
195 condstoretemp = NULL_TREE;
|
|
|
196 /* Calculate the set of non-trapping memory accesses. */
|
|
|
197 nontrap = get_non_trapping ();
|
|
|
198 }
|
|
|
199
|
|
|
200 /* Search every basic block for COND_EXPR we may be able to optimize.
|
|
|
201
|
|
|
202 We walk the blocks in order that guarantees that a block with
|
|
|
203 a single predecessor is processed before the predecessor.
|
|
|
204 This ensures that we collapse inner ifs before visiting the
|
|
|
205 outer ones, and also that we do not try to visit a removed
|
|
|
206 block. */
|
|
|
207 bb_order = blocks_in_phiopt_order ();
|
|
|
208 n = n_basic_blocks - NUM_FIXED_BLOCKS;
|
|
|
209
|
|
|
210 for (i = 0; i < n; i++)
|
|
|
211 {
|
|
|
212 gimple cond_stmt, phi;
|
|
|
213 basic_block bb1, bb2;
|
|
|
214 edge e1, e2;
|
|
|
215 tree arg0, arg1;
|
|
|
216
|
|
|
217 bb = bb_order[i];
|
|
|
218
|
|
|
219 cond_stmt = last_stmt (bb);
|
|
|
220 /* Check to see if the last statement is a GIMPLE_COND. */
|
|
|
221 if (!cond_stmt
|
|
|
222 || gimple_code (cond_stmt) != GIMPLE_COND)
|
|
|
223 continue;
|
|
|
224
|
|
|
225 e1 = EDGE_SUCC (bb, 0);
|
|
|
226 bb1 = e1->dest;
|
|
|
227 e2 = EDGE_SUCC (bb, 1);
|
|
|
228 bb2 = e2->dest;
|
|
|
229
|
|
|
230 /* We cannot do the optimization on abnormal edges. */
|
|
|
231 if ((e1->flags & EDGE_ABNORMAL) != 0
|
|
|
232 || (e2->flags & EDGE_ABNORMAL) != 0)
|
|
|
233 continue;
|
|
|
234
|
|
|
235 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */
|
|
|
236 if (EDGE_COUNT (bb1->succs) == 0
|
|
|
237 || bb2 == NULL
|
|
|
238 || EDGE_COUNT (bb2->succs) == 0)
|
|
|
239 continue;
|
|
|
240
|
|
|
241 /* Find the bb which is the fall through to the other. */
|
|
|
242 if (EDGE_SUCC (bb1, 0)->dest == bb2)
|
|
|
243 ;
|
|
|
244 else if (EDGE_SUCC (bb2, 0)->dest == bb1)
|
|
|
245 {
|
|
|
246 basic_block bb_tmp = bb1;
|
|
|
247 edge e_tmp = e1;
|
|
|
248 bb1 = bb2;
|
|
|
249 bb2 = bb_tmp;
|
|
|
250 e1 = e2;
|
|
|
251 e2 = e_tmp;
|
|
|
252 }
|
|
|
253 else
|
|
|
254 continue;
|
|
|
255
|
|
|
256 e1 = EDGE_SUCC (bb1, 0);
|
|
|
257
|
|
|
258 /* Make sure that bb1 is just a fall through. */
|
|
|
259 if (!single_succ_p (bb1)
|
|
|
260 || (e1->flags & EDGE_FALLTHRU) == 0)
|
|
|
261 continue;
|
|
|
262
|
|
|
263 /* Also make sure that bb1 only have one predecessor and that it
|
|
|
264 is bb. */
|
|
|
265 if (!single_pred_p (bb1)
|
|
|
266 || single_pred (bb1) != bb)
|
|
|
267 continue;
|
|
|
268
|
|
|
269 if (do_store_elim)
|
|
|
270 {
|
|
|
271 /* bb1 is the middle block, bb2 the join block, bb the split block,
|
|
|
272 e1 the fallthrough edge from bb1 to bb2. We can't do the
|
|
|
273 optimization if the join block has more than two predecessors. */
|
|
|
274 if (EDGE_COUNT (bb2->preds) > 2)
|
|
|
275 continue;
|
|
|
276 if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
|
|
|
277 cfgchanged = true;
|
|
|
278 }
|
|
|
279 else
|
|
|
280 {
|
|
|
281 gimple_seq phis = phi_nodes (bb2);
|
|
|
282
|
|
|
283 /* Check to make sure that there is only one PHI node.
|
|
|
284 TODO: we could do it with more than one iff the other PHI nodes
|
|
|
285 have the same elements for these two edges. */
|
|
|
286 if (! gimple_seq_singleton_p (phis))
|
|
|
287 continue;
|
|
|
288
|
|
|
289 phi = gsi_stmt (gsi_start (phis));
|
|
|
290 arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
|
|
|
291 arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
|
|
|
292
|
|
|
293 /* Something is wrong if we cannot find the arguments in the PHI
|
|
|
294 node. */
|
|
|
295 gcc_assert (arg0 != NULL && arg1 != NULL);
|
|
|
296
|
|
|
297 /* Do the replacement of conditional if it can be done. */
|
|
|
298 if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
|
|
|
299 cfgchanged = true;
|
|
|
300 else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
|
|
|
301 cfgchanged = true;
|
|
|
302 else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
|
|
|
303 cfgchanged = true;
|
|
|
304 else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
|
|
|
305 cfgchanged = true;
|
|
|
306 }
|
|
|
307 }
|
|
|
308
|
|
|
309 free (bb_order);
|
|
|
310
|
|
|
311 if (do_store_elim)
|
|
|
312 pointer_set_destroy (nontrap);
|
|
|
313 /* If the CFG has changed, we should cleanup the CFG. */
|
|
|
314 if (cfgchanged && do_store_elim)
|
|
|
315 {
|
|
|
316 /* In cond-store replacement we have added some loads on edges
|
|
|
317 and new VOPS (as we moved the store, and created a load). */
|
|
|
318 gsi_commit_edge_inserts ();
|
|
|
319 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
|
|
|
320 }
|
|
|
321 else if (cfgchanged)
|
|
|
322 return TODO_cleanup_cfg;
|
|
|
323 return 0;
|
|
|
324 }
|
|
|
325
|
|
|
326 /* Returns the list of basic blocks in the function in an order that guarantees
|
|
|
327 that if a block X has just a single predecessor Y, then Y is after X in the
|
|
|
328 ordering. */
|
|
|
329
|
|
|
330 basic_block *
|
|
|
331 blocks_in_phiopt_order (void)
|
|
|
332 {
|
|
|
333 basic_block x, y;
|
|
|
334 basic_block *order = XNEWVEC (basic_block, n_basic_blocks);
|
|
|
335 unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS;
|
|
|
336 unsigned np, i;
|
|
|
337 sbitmap visited = sbitmap_alloc (last_basic_block);
|
|
|
338
|
|
|
339 #define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index))
|
|
|
340 #define VISITED_P(BB) (TEST_BIT (visited, (BB)->index))
|
|
|
341
|
|
|
342 sbitmap_zero (visited);
|
|
|
343
|
|
|
344 MARK_VISITED (ENTRY_BLOCK_PTR);
|
|
|
345 FOR_EACH_BB (x)
|
|
|
346 {
|
|
|
347 if (VISITED_P (x))
|
|
|
348 continue;
|
|
|
349
|
|
|
350 /* Walk the predecessors of x as long as they have precisely one
|
|
|
351 predecessor and add them to the list, so that they get stored
|
|
|
352 after x. */
|
|
|
353 for (y = x, np = 1;
|
|
|
354 single_pred_p (y) && !VISITED_P (single_pred (y));
|
|
|
355 y = single_pred (y))
|
|
|
356 np++;
|
|
|
357 for (y = x, i = n - np;
|
|
|
358 single_pred_p (y) && !VISITED_P (single_pred (y));
|
|
|
359 y = single_pred (y), i++)
|
|
|
360 {
|
|
|
361 order[i] = y;
|
|
|
362 MARK_VISITED (y);
|
|
|
363 }
|
|
|
364 order[i] = y;
|
|
|
365 MARK_VISITED (y);
|
|
|
366
|
|
|
367 gcc_assert (i == n - 1);
|
|
|
368 n -= np;
|
|
|
369 }
|
|
|
370
|
|
|
371 sbitmap_free (visited);
|
|
|
372 gcc_assert (n == 0);
|
|
|
373 return order;
|
|
|
374
|
|
|
375 #undef MARK_VISITED
|
|
|
376 #undef VISITED_P
|
|
|
377 }
|
|
|
378
|
|
|
379
|
|
|
380 /* Return TRUE if block BB has no executable statements, otherwise return
|
|
|
381 FALSE. */
|
|
|
382
|
|
|
383 bool
|
|
|
384 empty_block_p (basic_block bb)
|
|
|
385 {
|
|
|
386 /* BB must have no executable statements. */
|
|
|
387 return gsi_end_p (gsi_after_labels (bb));
|
|
|
388 }
|
|
|
389
|
|
|
390 /* Replace PHI node element whose edge is E in block BB with variable NEW.
|
|
|
391 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
|
|
|
392 is known to have two edges, one of which must reach BB). */
|
|
|
393
|
|
|
394 static void
|
|
|
395 replace_phi_edge_with_variable (basic_block cond_block,
|
|
|
396 edge e, gimple phi, tree new_tree)
|
|
|
397 {
|
|
|
398 basic_block bb = gimple_bb (phi);
|
|
|
399 basic_block block_to_remove;
|
|
|
400 gimple_stmt_iterator gsi;
|
|
|
401
|
|
|
402 /* Change the PHI argument to new. */
|
|
|
403 SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
|
|
|
404
|
|
|
405 /* Remove the empty basic block. */
|
|
|
406 if (EDGE_SUCC (cond_block, 0)->dest == bb)
|
|
|
407 {
|
|
|
408 EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;
|
|
|
409 EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
|
|
|
410 EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE;
|
|
|
411 EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count;
|
|
|
412
|
|
|
413 block_to_remove = EDGE_SUCC (cond_block, 1)->dest;
|
|
|
414 }
|
|
|
415 else
|
|
|
416 {
|
|
|
417 EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;
|
|
|
418 EDGE_SUCC (cond_block, 1)->flags
|
|
|
419 &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
|
|
|
420 EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE;
|
|
|
421 EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count;
|
|
|
422
|
|
|
423 block_to_remove = EDGE_SUCC (cond_block, 0)->dest;
|
|
|
424 }
|
|
|
425 delete_basic_block (block_to_remove);
|
|
|
426
|
|
|
427 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */
|
|
|
428 gsi = gsi_last_bb (cond_block);
|
|
|
429 gsi_remove (&gsi, true);
|
|
|
430
|
|
|
431 if (dump_file && (dump_flags & TDF_DETAILS))
|
|
|
432 fprintf (dump_file,
|
|
|
433 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
|
|
|
434 cond_block->index,
|
|
|
435 bb->index);
|
|
|
436 }
|
|
|
437
|
|
|
438 /* The function conditional_replacement does the main work of doing the
|
|
|
439 conditional replacement. Return true if the replacement is done.
|
|
|
440 Otherwise return false.
|
|
|
441 BB is the basic block where the replacement is going to be done on. ARG0
|
|
|
442 is argument 0 from PHI. Likewise for ARG1. */
|
|
|
443
|
|
|
444 static bool
|
|
|
445 conditional_replacement (basic_block cond_bb, basic_block middle_bb,
|
|
|
446 edge e0, edge e1, gimple phi,
|
|
|
447 tree arg0, tree arg1)
|
|
|
448 {
|
|
|
449 tree result;
|
|
|
450 gimple stmt, new_stmt;
|
|
|
451 tree cond;
|
|
|
452 gimple_stmt_iterator gsi;
|
|
|
453 edge true_edge, false_edge;
|
|
|
454 tree new_var, new_var2;
|
|
|
455
|
|
|
456 /* FIXME: Gimplification of complex type is too hard for now. */
|
|
|
457 if (TREE_CODE (TREE_TYPE (arg0)) == COMPLEX_TYPE
|
|
|
458 || TREE_CODE (TREE_TYPE (arg1)) == COMPLEX_TYPE)
|
|
|
459 return false;
|
|
|
460
|
|
|
461 /* The PHI arguments have the constants 0 and 1, then convert
|
|
|
462 it to the conditional. */
|
|
|
463 if ((integer_zerop (arg0) && integer_onep (arg1))
|
|
|
464 || (integer_zerop (arg1) && integer_onep (arg0)))
|
|
|
465 ;
|
|
|
466 else
|
|
|
467 return false;
|
|
|
468
|
|
|
469 if (!empty_block_p (middle_bb))
|
|
|
470 return false;
|
|
|
471
|
|
|
472 /* At this point we know we have a GIMPLE_COND with two successors.
|
|
|
473 One successor is BB, the other successor is an empty block which
|
|
|
474 falls through into BB.
|
|
|
475
|
|
|
476 There is a single PHI node at the join point (BB) and its arguments
|
|
|
477 are constants (0, 1).
|
|
|
478
|
|
|
479 So, given the condition COND, and the two PHI arguments, we can
|
|
|
480 rewrite this PHI into non-branching code:
|
|
|
481
|
|
|
482 dest = (COND) or dest = COND'
|
|
|
483
|
|
|
484 We use the condition as-is if the argument associated with the
|
|
|
485 true edge has the value one or the argument associated with the
|
|
|
486 false edge as the value zero. Note that those conditions are not
|
|
|
487 the same since only one of the outgoing edges from the GIMPLE_COND
|
|
|
488 will directly reach BB and thus be associated with an argument. */
|
|
|
489
|
|
|
490 stmt = last_stmt (cond_bb);
|
|
|
491 result = PHI_RESULT (phi);
|
|
|
492
|
|
|
493 /* To handle special cases like floating point comparison, it is easier and
|
|
|
494 less error-prone to build a tree and gimplify it on the fly though it is
|
|
|
495 less efficient. */
|
|
|
496 cond = fold_build2 (gimple_cond_code (stmt), boolean_type_node,
|
|
|
497 gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
|
|
|
498
|
|
|
499 /* We need to know which is the true edge and which is the false
|
|
|
500 edge so that we know when to invert the condition below. */
|
|
|
501 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
|
|
|
502 if ((e0 == true_edge && integer_zerop (arg0))
|
|
|
503 || (e0 == false_edge && integer_onep (arg0))
|
|
|
504 || (e1 == true_edge && integer_zerop (arg1))
|
|
|
505 || (e1 == false_edge && integer_onep (arg1)))
|
|
|
506 cond = fold_build1 (TRUTH_NOT_EXPR, TREE_TYPE (cond), cond);
|
|
|
507
|
|
|
508 /* Insert our new statements at the end of conditional block before the
|
|
|
509 COND_STMT. */
|
|
|
510 gsi = gsi_for_stmt (stmt);
|
|
|
511 new_var = force_gimple_operand_gsi (&gsi, cond, true, NULL, true,
|
|
|
512 GSI_SAME_STMT);
|
|
|
513
|
|
|
514 if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (new_var)))
|
|
|
515 {
|
|
|
516 new_var2 = create_tmp_var (TREE_TYPE (result), NULL);
|
|
|
517 add_referenced_var (new_var2);
|
|
|
518 new_stmt = gimple_build_assign_with_ops (CONVERT_EXPR, new_var2,
|
|
|
519 new_var, NULL);
|
|
|
520 new_var2 = make_ssa_name (new_var2, new_stmt);
|
|
|
521 gimple_assign_set_lhs (new_stmt, new_var2);
|
|
|
522 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
|
|
|
523 new_var = new_var2;
|
|
|
524 }
|
|
|
525
|
|
|
526 replace_phi_edge_with_variable (cond_bb, e1, phi, new_var);
|
|
|
527
|
|
|
528 /* Note that we optimized this PHI. */
|
|
|
529 return true;
|
|
|
530 }
|
|
|
531
|
|
|
532 /* The function value_replacement does the main work of doing the value
|
|
|
533 replacement. Return true if the replacement is done. Otherwise return
|
|
|
534 false.
|
|
|
535 BB is the basic block where the replacement is going to be done on. ARG0
|
|
|
536 is argument 0 from the PHI. Likewise for ARG1. */
|
|
|
537
|
|
|
538 static bool
|
|
|
539 value_replacement (basic_block cond_bb, basic_block middle_bb,
|
|
|
540 edge e0, edge e1, gimple phi,
|
|
|
541 tree arg0, tree arg1)
|
|
|
542 {
|
|
|
543 gimple cond;
|
|
|
544 edge true_edge, false_edge;
|
|
|
545 enum tree_code code;
|
|
|
546
|
|
|
547 /* If the type says honor signed zeros we cannot do this
|
|
|
548 optimization. */
|
|
|
549 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
|
|
|
550 return false;
|
|
|
551
|
|
|
552 if (!empty_block_p (middle_bb))
|
|
|
553 return false;
|
|
|
554
|
|
|
555 cond = last_stmt (cond_bb);
|
|
|
556 code = gimple_cond_code (cond);
|
|
|
557
|
|
|
558 /* This transformation is only valid for equality comparisons. */
|
|
|
559 if (code != NE_EXPR && code != EQ_EXPR)
|
|
|
560 return false;
|
|
|
561
|
|
|
562 /* We need to know which is the true edge and which is the false
|
|
|
563 edge so that we know if have abs or negative abs. */
|
|
|
564 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
|
|
|
565
|
|
|
566 /* At this point we know we have a COND_EXPR with two successors.
|
|
|
567 One successor is BB, the other successor is an empty block which
|
|
|
568 falls through into BB.
|
|
|
569
|
|
|
570 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
|
|
|
571
|
|
|
572 There is a single PHI node at the join point (BB) with two arguments.
|
|
|
573
|
|
|
574 We now need to verify that the two arguments in the PHI node match
|
|
|
575 the two arguments to the equality comparison. */
|
|
|
576
|
|
|
577 if ((operand_equal_for_phi_arg_p (arg0, gimple_cond_lhs (cond))
|
|
|
578 && operand_equal_for_phi_arg_p (arg1, gimple_cond_rhs (cond)))
|
|
|
579 || (operand_equal_for_phi_arg_p (arg1, gimple_cond_lhs (cond))
|
|
|
580 && operand_equal_for_phi_arg_p (arg0, gimple_cond_rhs (cond))))
|
|
|
581 {
|
|
|
582 edge e;
|
|
|
583 tree arg;
|
|
|
584
|
|
|
585 /* For NE_EXPR, we want to build an assignment result = arg where
|
|
|
586 arg is the PHI argument associated with the true edge. For
|
|
|
587 EQ_EXPR we want the PHI argument associated with the false edge. */
|
|
|
588 e = (code == NE_EXPR ? true_edge : false_edge);
|
|
|
589
|
|
|
590 /* Unfortunately, E may not reach BB (it may instead have gone to
|
|
|
591 OTHER_BLOCK). If that is the case, then we want the single outgoing
|
|
|
592 edge from OTHER_BLOCK which reaches BB and represents the desired
|
|
|
593 path from COND_BLOCK. */
|
|
|
594 if (e->dest == middle_bb)
|
|
|
595 e = single_succ_edge (e->dest);
|
|
|
596
|
|
|
597 /* Now we know the incoming edge to BB that has the argument for the
|
|
|
598 RHS of our new assignment statement. */
|
|
|
599 if (e0 == e)
|
|
|
600 arg = arg0;
|
|
|
601 else
|
|
|
602 arg = arg1;
|
|
|
603
|
|
|
604 replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
|
|
|
605
|
|
|
606 /* Note that we optimized this PHI. */
|
|
|
607 return true;
|
|
|
608 }
|
|
|
609 return false;
|
|
|
610 }
|
|
|
611
|
|
|
612 /* The function minmax_replacement does the main work of doing the minmax
|
|
|
613 replacement. Return true if the replacement is done. Otherwise return
|
|
|
614 false.
|
|
|
615 BB is the basic block where the replacement is going to be done on. ARG0
|
|
|
616 is argument 0 from the PHI. Likewise for ARG1. */
|
|
|
617
|
|
|
618 static bool
|
|
|
619 minmax_replacement (basic_block cond_bb, basic_block middle_bb,
|
|
|
620 edge e0, edge e1, gimple phi,
|
|
|
621 tree arg0, tree arg1)
|
|
|
622 {
|
|
|
623 tree result, type;
|
|
|
624 gimple cond, new_stmt;
|
|
|
625 edge true_edge, false_edge;
|
|
|
626 enum tree_code cmp, minmax, ass_code;
|
|
|
627 tree smaller, larger, arg_true, arg_false;
|
|
|
628 gimple_stmt_iterator gsi, gsi_from;
|
|
|
629
|
|
|
630 type = TREE_TYPE (PHI_RESULT (phi));
|
|
|
631
|
|
|
632 /* The optimization may be unsafe due to NaNs. */
|
|
|
633 if (HONOR_NANS (TYPE_MODE (type)))
|
|
|
634 return false;
|
|
|
635
|
|
|
636 cond = last_stmt (cond_bb);
|
|
|
637 cmp = gimple_cond_code (cond);
|
|
|
638 result = PHI_RESULT (phi);
|
|
|
639
|
|
|
640 /* This transformation is only valid for order comparisons. Record which
|
|
|
641 operand is smaller/larger if the result of the comparison is true. */
|
|
|
642 if (cmp == LT_EXPR || cmp == LE_EXPR)
|
|
|
643 {
|
|
|
644 smaller = gimple_cond_lhs (cond);
|
|
|
645 larger = gimple_cond_rhs (cond);
|
|
|
646 }
|
|
|
647 else if (cmp == GT_EXPR || cmp == GE_EXPR)
|
|
|
648 {
|
|
|
649 smaller = gimple_cond_rhs (cond);
|
|
|
650 larger = gimple_cond_lhs (cond);
|
|
|
651 }
|
|
|
652 else
|
|
|
653 return false;
|
|
|
654
|
|
|
655 /* We need to know which is the true edge and which is the false
|
|
|
656 edge so that we know if have abs or negative abs. */
|
|
|
657 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
|
|
|
658
|
|
|
659 /* Forward the edges over the middle basic block. */
|
|
|
660 if (true_edge->dest == middle_bb)
|
|
|
661 true_edge = EDGE_SUCC (true_edge->dest, 0);
|
|
|
662 if (false_edge->dest == middle_bb)
|
|
|
663 false_edge = EDGE_SUCC (false_edge->dest, 0);
|
|
|
664
|
|
|
665 if (true_edge == e0)
|
|
|
666 {
|
|
|
667 gcc_assert (false_edge == e1);
|
|
|
668 arg_true = arg0;
|
|
|
669 arg_false = arg1;
|
|
|
670 }
|
|
|
671 else
|
|
|
672 {
|
|
|
673 gcc_assert (false_edge == e0);
|
|
|
674 gcc_assert (true_edge == e1);
|
|
|
675 arg_true = arg1;
|
|
|
676 arg_false = arg0;
|
|
|
677 }
|
|
|
678
|
|
|
679 if (empty_block_p (middle_bb))
|
|
|
680 {
|
|
|
681 if (operand_equal_for_phi_arg_p (arg_true, smaller)
|
|
|
682 && operand_equal_for_phi_arg_p (arg_false, larger))
|
|
|
683 {
|
|
|
684 /* Case
|
|
|
685
|
|
|
686 if (smaller < larger)
|
|
|
687 rslt = smaller;
|
|
|
688 else
|
|
|
689 rslt = larger; */
|
|
|
690 minmax = MIN_EXPR;
|
|
|
691 }
|
|
|
692 else if (operand_equal_for_phi_arg_p (arg_false, smaller)
|
|
|
693 && operand_equal_for_phi_arg_p (arg_true, larger))
|
|
|
694 minmax = MAX_EXPR;
|
|
|
695 else
|
|
|
696 return false;
|
|
|
697 }
|
|
|
698 else
|
|
|
699 {
|
|
|
700 /* Recognize the following case, assuming d <= u:
|
|
|
701
|
|
|
702 if (a <= u)
|
|
|
703 b = MAX (a, d);
|
|
|
704 x = PHI <b, u>
|
|
|
705
|
|
|
706 This is equivalent to
|
|
|
707
|
|
|
708 b = MAX (a, d);
|
|
|
709 x = MIN (b, u); */
|
|
|
710
|
|
|
711 gimple assign = last_and_only_stmt (middle_bb);
|
|
|
712 tree lhs, op0, op1, bound;
|
|
|
713
|
|
|
714 if (!assign
|
|
|
715 || gimple_code (assign) != GIMPLE_ASSIGN)
|
|
|
716 return false;
|
|
|
717
|
|
|
718 lhs = gimple_assign_lhs (assign);
|
|
|
719 ass_code = gimple_assign_rhs_code (assign);
|
|
|
720 if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
|
|
|
721 return false;
|
|
|
722 op0 = gimple_assign_rhs1 (assign);
|
|
|
723 op1 = gimple_assign_rhs2 (assign);
|
|
|
724
|
|
|
725 if (true_edge->src == middle_bb)
|
|
|
726 {
|
|
|
727 /* We got here if the condition is true, i.e., SMALLER < LARGER. */
|
|
|
728 if (!operand_equal_for_phi_arg_p (lhs, arg_true))
|
|
|
729 return false;
|
|
|
730
|
|
|
731 if (operand_equal_for_phi_arg_p (arg_false, larger))
|
|
|
732 {
|
|
|
733 /* Case
|
|
|
734
|
|
|
735 if (smaller < larger)
|
|
|
736 {
|
|
|
737 r' = MAX_EXPR (smaller, bound)
|
|
|
738 }
|
|
|
739 r = PHI <r', larger> --> to be turned to MIN_EXPR. */
|
|
|
740 if (ass_code != MAX_EXPR)
|
|
|
741 return false;
|
|
|
742
|
|
|
743 minmax = MIN_EXPR;
|
|
|
744 if (operand_equal_for_phi_arg_p (op0, smaller))
|
|
|
745 bound = op1;
|
|
|
746 else if (operand_equal_for_phi_arg_p (op1, smaller))
|
|
|
747 bound = op0;
|
|
|
748 else
|
|
|
749 return false;
|
|
|
750
|
|
|
751 /* We need BOUND <= LARGER. */
|
|
|
752 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
|
|
|
753 bound, larger)))
|
|
|
754 return false;
|
|
|
755 }
|
|
|
756 else if (operand_equal_for_phi_arg_p (arg_false, smaller))
|
|
|
757 {
|
|
|
758 /* Case
|
|
|
759
|
|
|
760 if (smaller < larger)
|
|
|
761 {
|
|
|
762 r' = MIN_EXPR (larger, bound)
|
|
|
763 }
|
|
|
764 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */
|
|
|
765 if (ass_code != MIN_EXPR)
|
|
|
766 return false;
|
|
|
767
|
|
|
768 minmax = MAX_EXPR;
|
|
|
769 if (operand_equal_for_phi_arg_p (op0, larger))
|
|
|
770 bound = op1;
|
|
|
771 else if (operand_equal_for_phi_arg_p (op1, larger))
|
|
|
772 bound = op0;
|
|
|
773 else
|
|
|
774 return false;
|
|
|
775
|
|
|
776 /* We need BOUND >= SMALLER. */
|
|
|
777 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
|
|
|
778 bound, smaller)))
|
|
|
779 return false;
|
|
|
780 }
|
|
|
781 else
|
|
|
782 return false;
|
|
|
783 }
|
|
|
784 else
|
|
|
785 {
|
|
|
786 /* We got here if the condition is false, i.e., SMALLER > LARGER. */
|
|
|
787 if (!operand_equal_for_phi_arg_p (lhs, arg_false))
|
|
|
788 return false;
|
|
|
789
|
|
|
790 if (operand_equal_for_phi_arg_p (arg_true, larger))
|
|
|
791 {
|
|
|
792 /* Case
|
|
|
793
|
|
|
794 if (smaller > larger)
|
|
|
795 {
|
|
|
796 r' = MIN_EXPR (smaller, bound)
|
|
|
797 }
|
|
|
798 r = PHI <r', larger> --> to be turned to MAX_EXPR. */
|
|
|
799 if (ass_code != MIN_EXPR)
|
|
|
800 return false;
|
|
|
801
|
|
|
802 minmax = MAX_EXPR;
|
|
|
803 if (operand_equal_for_phi_arg_p (op0, smaller))
|
|
|
804 bound = op1;
|
|
|
805 else if (operand_equal_for_phi_arg_p (op1, smaller))
|
|
|
806 bound = op0;
|
|
|
807 else
|
|
|
808 return false;
|
|
|
809
|
|
|
810 /* We need BOUND >= LARGER. */
|
|
|
811 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
|
|
|
812 bound, larger)))
|
|
|
813 return false;
|
|
|
814 }
|
|
|
815 else if (operand_equal_for_phi_arg_p (arg_true, smaller))
|
|
|
816 {
|
|
|
817 /* Case
|
|
|
818
|
|
|
819 if (smaller > larger)
|
|
|
820 {
|
|
|
821 r' = MAX_EXPR (larger, bound)
|
|
|
822 }
|
|
|
823 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */
|
|
|
824 if (ass_code != MAX_EXPR)
|
|
|
825 return false;
|
|
|
826
|
|
|
827 minmax = MIN_EXPR;
|
|
|
828 if (operand_equal_for_phi_arg_p (op0, larger))
|
|
|
829 bound = op1;
|
|
|
830 else if (operand_equal_for_phi_arg_p (op1, larger))
|
|
|
831 bound = op0;
|
|
|
832 else
|
|
|
833 return false;
|
|
|
834
|
|
|
835 /* We need BOUND <= SMALLER. */
|
|
|
836 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
|
|
|
837 bound, smaller)))
|
|
|
838 return false;
|
|
|
839 }
|
|
|
840 else
|
|
|
841 return false;
|
|
|
842 }
|
|
|
843
|
|
|
844 /* Move the statement from the middle block. */
|
|
|
845 gsi = gsi_last_bb (cond_bb);
|
|
|
846 gsi_from = gsi_last_bb (middle_bb);
|
|
|
847 gsi_move_before (&gsi_from, &gsi);
|
|
|
848 }
|
|
|
849
|
|
|
850 /* Emit the statement to compute min/max. */
|
|
|
851 result = duplicate_ssa_name (PHI_RESULT (phi), NULL);
|
|
|
852 new_stmt = gimple_build_assign_with_ops (minmax, result, arg0, arg1);
|
|
|
853 gsi = gsi_last_bb (cond_bb);
|
|
|
854 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
|
|
|
855
|
|
|
856 replace_phi_edge_with_variable (cond_bb, e1, phi, result);
|
|
|
857 return true;
|
|
|
858 }
|
|
|
859
|
|
|
860 /* The function absolute_replacement does the main work of doing the absolute
|
|
|
861 replacement. Return true if the replacement is done. Otherwise return
|
|
|
862 false.
|
|
|
863 bb is the basic block where the replacement is going to be done on. arg0
|
|
|
864 is argument 0 from the phi. Likewise for arg1. */
|
|
|
865
|
|
|
866 static bool
|
|
|
867 abs_replacement (basic_block cond_bb, basic_block middle_bb,
|
|
|
868 edge e0 ATTRIBUTE_UNUSED, edge e1,
|
|
|
869 gimple phi, tree arg0, tree arg1)
|
|
|
870 {
|
|
|
871 tree result;
|
|
|
872 gimple new_stmt, cond;
|
|
|
873 gimple_stmt_iterator gsi;
|
|
|
874 edge true_edge, false_edge;
|
|
|
875 gimple assign;
|
|
|
876 edge e;
|
|
|
877 tree rhs, lhs;
|
|
|
878 bool negate;
|
|
|
879 enum tree_code cond_code;
|
|
|
880
|
|
|
881 /* If the type says honor signed zeros we cannot do this
|
|
|
882 optimization. */
|
|
|
883 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
|
|
|
884 return false;
|
|
|
885
|
|
|
886 /* OTHER_BLOCK must have only one executable statement which must have the
|
|
|
887 form arg0 = -arg1 or arg1 = -arg0. */
|
|
|
888
|
|
|
889 assign = last_and_only_stmt (middle_bb);
|
|
|
890 /* If we did not find the proper negation assignment, then we can not
|
|
|
891 optimize. */
|
|
|
892 if (assign == NULL)
|
|
|
893 return false;
|
|
|
894
|
|
|
895 /* If we got here, then we have found the only executable statement
|
|
|
896 in OTHER_BLOCK. If it is anything other than arg = -arg1 or
|
|
|
897 arg1 = -arg0, then we can not optimize. */
|
|
|
898 if (gimple_code (assign) != GIMPLE_ASSIGN)
|
|
|
899 return false;
|
|
|
900
|
|
|
901 lhs = gimple_assign_lhs (assign);
|
|
|
902
|
|
|
903 if (gimple_assign_rhs_code (assign) != NEGATE_EXPR)
|
|
|
904 return false;
|
|
|
905
|
|
|
906 rhs = gimple_assign_rhs1 (assign);
|
|
|
907
|
|
|
908 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */
|
|
|
909 if (!(lhs == arg0 && rhs == arg1)
|
|
|
910 && !(lhs == arg1 && rhs == arg0))
|
|
|
911 return false;
|
|
|
912
|
|
|
913 cond = last_stmt (cond_bb);
|
|
|
914 result = PHI_RESULT (phi);
|
|
|
915
|
|
|
916 /* Only relationals comparing arg[01] against zero are interesting. */
|
|
|
917 cond_code = gimple_cond_code (cond);
|
|
|
918 if (cond_code != GT_EXPR && cond_code != GE_EXPR
|
|
|
919 && cond_code != LT_EXPR && cond_code != LE_EXPR)
|
|
|
920 return false;
|
|
|
921
|
|
|
922 /* Make sure the conditional is arg[01] OP y. */
|
|
|
923 if (gimple_cond_lhs (cond) != rhs)
|
|
|
924 return false;
|
|
|
925
|
|
|
926 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond)))
|
|
|
927 ? real_zerop (gimple_cond_rhs (cond))
|
|
|
928 : integer_zerop (gimple_cond_rhs (cond)))
|
|
|
929 ;
|
|
|
930 else
|
|
|
931 return false;
|
|
|
932
|
|
|
933 /* We need to know which is the true edge and which is the false
|
|
|
934 edge so that we know if have abs or negative abs. */
|
|
|
935 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
|
|
|
936
|
|
|
937 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
|
|
|
938 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if
|
|
|
939 the false edge goes to OTHER_BLOCK. */
|
|
|
940 if (cond_code == GT_EXPR || cond_code == GE_EXPR)
|
|
|
941 e = true_edge;
|
|
|
942 else
|
|
|
943 e = false_edge;
|
|
|
944
|
|
|
945 if (e->dest == middle_bb)
|
|
|
946 negate = true;
|
|
|
947 else
|
|
|
948 negate = false;
|
|
|
949
|
|
|
950 result = duplicate_ssa_name (result, NULL);
|
|
|
951
|
|
|
952 if (negate)
|
|
|
953 {
|
|
|
954 tree tmp = create_tmp_var (TREE_TYPE (result), NULL);
|
|
|
955 add_referenced_var (tmp);
|
|
|
956 lhs = make_ssa_name (tmp, NULL);
|
|
|
957 }
|
|
|
958 else
|
|
|
959 lhs = result;
|
|
|
960
|
|
|
961 /* Build the modify expression with abs expression. */
|
|
|
962 new_stmt = gimple_build_assign_with_ops (ABS_EXPR, lhs, rhs, NULL);
|
|
|
963
|
|
|
964 gsi = gsi_last_bb (cond_bb);
|
|
|
965 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
|
|
|
966
|
|
|
967 if (negate)
|
|
|
968 {
|
|
|
969 /* Get the right GSI. We want to insert after the recently
|
|
|
970 added ABS_EXPR statement (which we know is the first statement
|
|
|
971 in the block. */
|
|
|
972 new_stmt = gimple_build_assign_with_ops (NEGATE_EXPR, result, lhs, NULL);
|
|
|
973
|
|
|
974 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
|
|
|
975 }
|
|
|
976
|
|
|
977 replace_phi_edge_with_variable (cond_bb, e1, phi, result);
|
|
|
978
|
|
|
979 /* Note that we optimized this PHI. */
|
|
|
980 return true;
|
|
|
981 }
|
|
|
982
|
|
|
983 /* Auxiliary functions to determine the set of memory accesses which
|
|
|
984 can't trap because they are preceded by accesses to the same memory
|
|
|
985 portion. We do that for INDIRECT_REFs, so we only need to track
|
|
|
986 the SSA_NAME of the pointer indirectly referenced. The algorithm
|
|
|
987 simply is a walk over all instructions in dominator order. When
|
|
|
988 we see an INDIRECT_REF we determine if we've already seen a same
|
|
|
989 ref anywhere up to the root of the dominator tree. If we do the
|
|
|
990 current access can't trap. If we don't see any dominating access
|
|
|
991 the current access might trap, but might also make later accesses
|
|
|
992 non-trapping, so we remember it. We need to be careful with loads
|
|
|
993 or stores, for instance a load might not trap, while a store would,
|
|
|
994 so if we see a dominating read access this doesn't mean that a later
|
|
|
995 write access would not trap. Hence we also need to differentiate the
|
|
|
996 type of access(es) seen.
|
|
|
997
|
|
|
998 ??? We currently are very conservative and assume that a load might
|
|
|
999 trap even if a store doesn't (write-only memory). This probably is
|
|
|
1000 overly conservative. */
|
|
|
1001
|
|
|
1002 /* A hash-table of SSA_NAMEs, and in which basic block an INDIRECT_REF
|
|
|
1003 through it was seen, which would constitute a no-trap region for
|
|
|
1004 same accesses. */
|
|
|
1005 struct name_to_bb
|
|
|
1006 {
|
|
|
1007 tree ssa_name;
|
|
|
1008 basic_block bb;
|
|
|
1009 unsigned store : 1;
|
|
|
1010 };
|
|
|
1011
|
|
|
1012 /* The hash table for remembering what we've seen. */
|
|
|
1013 static htab_t seen_ssa_names;
|
|
|
1014
|
|
|
1015 /* The set of INDIRECT_REFs which can't trap. */
|
|
|
1016 static struct pointer_set_t *nontrap_set;
|
|
|
1017
|
|
|
1018 /* The hash function, based on the pointer to the pointer SSA_NAME. */
|
|
|
1019 static hashval_t
|
|
|
1020 name_to_bb_hash (const void *p)
|
|
|
1021 {
|
|
|
1022 const_tree n = ((const struct name_to_bb *)p)->ssa_name;
|
|
|
1023 return htab_hash_pointer (n) ^ ((const struct name_to_bb *)p)->store;
|
|
|
1024 }
|
|
|
1025
|
|
|
1026 /* The equality function of *P1 and *P2. SSA_NAMEs are shared, so
|
|
|
1027 it's enough to simply compare them for equality. */
|
|
|
1028 static int
|
|
|
1029 name_to_bb_eq (const void *p1, const void *p2)
|
|
|
1030 {
|
|
|
1031 const struct name_to_bb *n1 = (const struct name_to_bb *)p1;
|
|
|
1032 const struct name_to_bb *n2 = (const struct name_to_bb *)p2;
|
|
|
1033
|
|
|
1034 return n1->ssa_name == n2->ssa_name && n1->store == n2->store;
|
|
|
1035 }
|
|
|
1036
|
|
|
1037 /* We see the expression EXP in basic block BB. If it's an interesting
|
|
|
1038 expression (an INDIRECT_REF through an SSA_NAME) possibly insert the
|
|
|
1039 expression into the set NONTRAP or the hash table of seen expressions.
|
|
|
1040 STORE is true if this expression is on the LHS, otherwise it's on
|
|
|
1041 the RHS. */
|
|
|
1042 static void
|
|
|
1043 add_or_mark_expr (basic_block bb, tree exp,
|
|
|
1044 struct pointer_set_t *nontrap, bool store)
|
|
|
1045 {
|
|
|
1046 if (INDIRECT_REF_P (exp)
|
|
|
1047 && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME)
|
|
|
1048 {
|
|
|
1049 tree name = TREE_OPERAND (exp, 0);
|
|
|
1050 struct name_to_bb map;
|
|
|
1051 void **slot;
|
|
|
1052 struct name_to_bb *n2bb;
|
|
|
1053 basic_block found_bb = 0;
|
|
|
1054
|
|
|
1055 /* Try to find the last seen INDIRECT_REF through the same
|
|
|
1056 SSA_NAME, which can trap. */
|
|
|
1057 map.ssa_name = name;
|
|
|
1058 map.bb = 0;
|
|
|
1059 map.store = store;
|
|
|
1060 slot = htab_find_slot (seen_ssa_names, &map, INSERT);
|
|
|
1061 n2bb = (struct name_to_bb *) *slot;
|
|
|
1062 if (n2bb)
|
|
|
1063 found_bb = n2bb->bb;
|
|
|
1064
|
|
|
1065 /* If we've found a trapping INDIRECT_REF, _and_ it dominates EXP
|
|
|
1066 (it's in a basic block on the path from us to the dominator root)
|
|
|
1067 then we can't trap. */
|
|
|
1068 if (found_bb && found_bb->aux == (void *)1)
|
|
|
1069 {
|
|
|
1070 pointer_set_insert (nontrap, exp);
|
|
|
1071 }
|
|
|
1072 else
|
|
|
1073 {
|
|
|
1074 /* EXP might trap, so insert it into the hash table. */
|
|
|
1075 if (n2bb)
|
|
|
1076 {
|
|
|
1077 n2bb->bb = bb;
|
|
|
1078 }
|
|
|
1079 else
|
|
|
1080 {
|
|
|
1081 n2bb = XNEW (struct name_to_bb);
|
|
|
1082 n2bb->ssa_name = name;
|
|
|
1083 n2bb->bb = bb;
|
|
|
1084 n2bb->store = store;
|
|
|
1085 *slot = n2bb;
|
|
|
1086 }
|
|
|
1087 }
|
|
|
1088 }
|
|
|
1089 }
|
|
|
1090
|
|
|
1091 /* Called by walk_dominator_tree, when entering the block BB. */
|
|
|
1092 static void
|
|
|
1093 nt_init_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb)
|
|
|
1094 {
|
|
|
1095 gimple_stmt_iterator gsi;
|
|
|
1096 /* Mark this BB as being on the path to dominator root. */
|
|
|
1097 bb->aux = (void*)1;
|
|
|
1098
|
|
|
1099 /* And walk the statements in order. */
|
|
|
1100 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
|
|
|
1101 {
|
|
|
1102 gimple stmt = gsi_stmt (gsi);
|
|
|
1103
|
|
|
1104 if (is_gimple_assign (stmt))
|
|
|
1105 {
|
|
|
1106 add_or_mark_expr (bb, gimple_assign_lhs (stmt), nontrap_set, true);
|
|
|
1107 add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), nontrap_set, false);
|
|
|
1108 if (get_gimple_rhs_num_ops (gimple_assign_rhs_code (stmt)) > 1)
|
|
|
1109 add_or_mark_expr (bb, gimple_assign_rhs2 (stmt), nontrap_set,
|
|
|
1110 false);
|
|
|
1111 }
|
|
|
1112 }
|
|
|
1113 }
|
|
|
1114
|
|
|
1115 /* Called by walk_dominator_tree, when basic block BB is exited. */
|
|
|
1116 static void
|
|
|
1117 nt_fini_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb)
|
|
|
1118 {
|
|
|
1119 /* This BB isn't on the path to dominator root anymore. */
|
|
|
1120 bb->aux = NULL;
|
|
|
1121 }
|
|
|
1122
|
|
|
1123 /* This is the entry point of gathering non trapping memory accesses.
|
|
|
1124 It will do a dominator walk over the whole function, and it will
|
|
|
1125 make use of the bb->aux pointers. It returns a set of trees
|
|
|
1126 (the INDIRECT_REFs itself) which can't trap. */
|
|
|
1127 static struct pointer_set_t *
|
|
|
1128 get_non_trapping (void)
|
|
|
1129 {
|
|
|
1130 struct pointer_set_t *nontrap;
|
|
|
1131 struct dom_walk_data walk_data;
|
|
|
1132
|
|
|
1133 nontrap = pointer_set_create ();
|
|
|
1134 seen_ssa_names = htab_create (128, name_to_bb_hash, name_to_bb_eq,
|
|
|
1135 free);
|
|
|
1136 /* We're going to do a dominator walk, so ensure that we have
|
|
|
1137 dominance information. */
|
|
|
1138 calculate_dominance_info (CDI_DOMINATORS);
|
|
|
1139
|
|
|
1140 /* Setup callbacks for the generic dominator tree walker. */
|
|
|
1141 nontrap_set = nontrap;
|
|
|
1142 walk_data.walk_stmts_backward = false;
|
|
|
1143 walk_data.dom_direction = CDI_DOMINATORS;
|
|
|
1144 walk_data.initialize_block_local_data = NULL;
|
|
|
1145 walk_data.before_dom_children_before_stmts = nt_init_block;
|
|
|
1146 walk_data.before_dom_children_walk_stmts = NULL;
|
|
|
1147 walk_data.before_dom_children_after_stmts = NULL;
|
|
|
1148 walk_data.after_dom_children_before_stmts = NULL;
|
|
|
1149 walk_data.after_dom_children_walk_stmts = NULL;
|
|
|
1150 walk_data.after_dom_children_after_stmts = nt_fini_block;
|
|
|
1151 walk_data.global_data = NULL;
|
|
|
1152 walk_data.block_local_data_size = 0;
|
|
|
1153 walk_data.interesting_blocks = NULL;
|
|
|
1154
|
|
|
1155 init_walk_dominator_tree (&walk_data);
|
|
|
1156 walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
|
|
|
1157 fini_walk_dominator_tree (&walk_data);
|
|
|
1158 htab_delete (seen_ssa_names);
|
|
|
1159
|
|
|
1160 return nontrap;
|
|
|
1161 }
|
|
|
1162
|
|
|
1163 /* Do the main work of conditional store replacement. We already know
|
|
|
1164 that the recognized pattern looks like so:
|
|
|
1165
|
|
|
1166 split:
|
|
|
1167 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
|
|
|
1168 MIDDLE_BB:
|
|
|
1169 something
|
|
|
1170 fallthrough (edge E0)
|
|
|
1171 JOIN_BB:
|
|
|
1172 some more
|
|
|
1173
|
|
|
1174 We check that MIDDLE_BB contains only one store, that that store
|
|
|
1175 doesn't trap (not via NOTRAP, but via checking if an access to the same
|
|
|
1176 memory location dominates us) and that the store has a "simple" RHS. */
|
|
|
1177
|
|
|
1178 static bool
|
|
|
1179 cond_store_replacement (basic_block middle_bb, basic_block join_bb,
|
|
|
1180 edge e0, edge e1, struct pointer_set_t *nontrap)
|
|
|
1181 {
|
|
|
1182 gimple assign = last_and_only_stmt (middle_bb);
|
|
|
1183 tree lhs, rhs, name;
|
|
|
1184 gimple newphi, new_stmt;
|
|
|
1185 gimple_stmt_iterator gsi;
|
|
|
1186 enum tree_code code;
|
|
|
1187
|
|
|
1188 /* Check if middle_bb contains of only one store. */
|
|
|
1189 if (!assign
|
|
|
1190 || gimple_code (assign) != GIMPLE_ASSIGN)
|
|
|
1191 return false;
|
|
|
1192
|
|
|
1193 lhs = gimple_assign_lhs (assign);
|
|
|
1194 rhs = gimple_assign_rhs1 (assign);
|
|
|
1195 if (!INDIRECT_REF_P (lhs))
|
|
|
1196 return false;
|
|
|
1197
|
|
|
1198 /* RHS is either a single SSA_NAME or a constant. */
|
|
|
1199 code = gimple_assign_rhs_code (assign);
|
|
|
1200 if (get_gimple_rhs_class (code) != GIMPLE_SINGLE_RHS
|
|
|
1201 || (code != SSA_NAME && !is_gimple_min_invariant (rhs)))
|
|
|
1202 return false;
|
|
|
1203 /* Prove that we can move the store down. We could also check
|
|
|
1204 TREE_THIS_NOTRAP here, but in that case we also could move stores,
|
|
|
1205 whose value is not available readily, which we want to avoid. */
|
|
|
1206 if (!pointer_set_contains (nontrap, lhs))
|
|
|
1207 return false;
|
|
|
1208
|
|
|
1209 /* Now we've checked the constraints, so do the transformation:
|
|
|
1210 1) Remove the single store. */
|
|
|
1211 mark_symbols_for_renaming (assign);
|
|
|
1212 gsi = gsi_for_stmt (assign);
|
|
|
1213 gsi_remove (&gsi, true);
|
|
|
1214
|
|
|
1215 /* 2) Create a temporary where we can store the old content
|
|
|
1216 of the memory touched by the store, if we need to. */
|
|
|
1217 if (!condstoretemp || TREE_TYPE (lhs) != TREE_TYPE (condstoretemp))
|
|
|
1218 {
|
|
|
1219 condstoretemp = create_tmp_var (TREE_TYPE (lhs), "cstore");
|
|
|
1220 get_var_ann (condstoretemp);
|
|
|
1221 if (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE
|
|
|
1222 || TREE_CODE (TREE_TYPE (lhs)) == VECTOR_TYPE)
|
|
|
1223 DECL_GIMPLE_REG_P (condstoretemp) = 1;
|
|
|
1224 }
|
|
|
1225 add_referenced_var (condstoretemp);
|
|
|
1226
|
|
|
1227 /* 3) Insert a load from the memory of the store to the temporary
|
|
|
1228 on the edge which did not contain the store. */
|
|
|
1229 lhs = unshare_expr (lhs);
|
|
|
1230 new_stmt = gimple_build_assign (condstoretemp, lhs);
|
|
|
1231 name = make_ssa_name (condstoretemp, new_stmt);
|
|
|
1232 gimple_assign_set_lhs (new_stmt, name);
|
|
|
1233 mark_symbols_for_renaming (new_stmt);
|
|
|
1234 gsi_insert_on_edge (e1, new_stmt);
|
|
|
1235
|
|
|
1236 /* 4) Create a PHI node at the join block, with one argument
|
|
|
1237 holding the old RHS, and the other holding the temporary
|
|
|
1238 where we stored the old memory contents. */
|
|
|
1239 newphi = create_phi_node (condstoretemp, join_bb);
|
|
|
1240 add_phi_arg (newphi, rhs, e0);
|
|
|
1241 add_phi_arg (newphi, name, e1);
|
|
|
1242
|
|
|
1243 lhs = unshare_expr (lhs);
|
|
|
1244 new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
|
|
|
1245 mark_symbols_for_renaming (new_stmt);
|
|
|
1246
|
|
|
1247 /* 5) Insert that PHI node. */
|
|
|
1248 gsi = gsi_after_labels (join_bb);
|
|
|
1249 if (gsi_end_p (gsi))
|
|
|
1250 {
|
|
|
1251 gsi = gsi_last_bb (join_bb);
|
|
|
1252 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
|
|
|
1253 }
|
|
|
1254 else
|
|
|
1255 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
|
|
|
1256
|
|
|
1257 return true;
|
|
|
1258 }
|
|
|
1259
|
|
|
1260 /* Always do these optimizations if we have SSA
|
|
|
1261 trees to work on. */
|
|
|
1262 static bool
|
|
|
1263 gate_phiopt (void)
|
|
|
1264 {
|
|
|
1265 return 1;
|
|
|
1266 }
|
|
|
1267
|
|
|
1268 struct gimple_opt_pass pass_phiopt =
|
|
|
1269 {
|
|
|
1270 {
|
|
|
1271 GIMPLE_PASS,
|
|
|
1272 "phiopt", /* name */
|
|
|
1273 gate_phiopt, /* gate */
|
|
|
1274 tree_ssa_phiopt, /* execute */
|
|
|
1275 NULL, /* sub */
|
|
|
1276 NULL, /* next */
|
|
|
1277 0, /* static_pass_number */
|
|
|
1278 TV_TREE_PHIOPT, /* tv_id */
|
|
|
1279 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
|
|
|
1280 0, /* properties_provided */
|
|
|
1281 0, /* properties_destroyed */
|
|
|
1282 0, /* todo_flags_start */
|
|
|
1283 TODO_dump_func
|
|
|
1284 | TODO_ggc_collect
|
|
|
1285 | TODO_verify_ssa
|
|
|
1286 | TODO_verify_flow
|
|
|
1287 | TODO_verify_stmts /* todo_flags_finish */
|
|
|
1288 }
|
|
|
1289 };
|
|
|
1290
|
|
|
1291 static bool
|
|
|
1292 gate_cselim (void)
|
|
|
1293 {
|
|
|
1294 return flag_tree_cselim;
|
|
|
1295 }
|
|
|
1296
|
|
|
1297 struct gimple_opt_pass pass_cselim =
|
|
|
1298 {
|
|
|
1299 {
|
|
|
1300 GIMPLE_PASS,
|
|
|
1301 "cselim", /* name */
|
|
|
1302 gate_cselim, /* gate */
|
|
|
1303 tree_ssa_cs_elim, /* execute */
|
|
|
1304 NULL, /* sub */
|
|
|
1305 NULL, /* next */
|
|
|
1306 0, /* static_pass_number */
|
|
|
1307 TV_TREE_PHIOPT, /* tv_id */
|
|
|
1308 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
|
|
|
1309 0, /* properties_provided */
|
|
|
1310 0, /* properties_destroyed */
|
|
|
1311 0, /* todo_flags_start */
|
|
|
1312 TODO_dump_func
|
|
|
1313 | TODO_ggc_collect
|
|
|
1314 | TODO_verify_ssa
|
|
|
1315 | TODO_verify_flow
|
|
|
1316 | TODO_verify_stmts /* todo_flags_finish */
|
|
|
1317 }
|
|
|
1318 };
|
