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Commit | Line | Data |
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e9eb809d | 1 | /* Functions to determine/estimate number of iterations of a loop. |
23a5b65a | 2 | Copyright (C) 2004-2014 Free Software Foundation, Inc. |
b8698a0f | 3 | |
e9eb809d | 4 | This file is part of GCC. |
b8698a0f | 5 | |
e9eb809d ZD |
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 | |
9dcd6f09 | 8 | Free Software Foundation; either version 3, or (at your option) any |
e9eb809d | 9 | later version. |
b8698a0f | 10 | |
e9eb809d ZD |
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. | |
b8698a0f | 15 | |
e9eb809d | 16 | You should have received a copy of the GNU General Public License |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
e9eb809d ZD |
19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
24 | #include "tree.h" | |
d8a2d370 DN |
25 | #include "calls.h" |
26 | #include "expr.h" | |
e9eb809d | 27 | #include "tm_p.h" |
e9eb809d | 28 | #include "basic-block.h" |
cf835838 | 29 | #include "gimple-pretty-print.h" |
f9cc1a70 | 30 | #include "intl.h" |
2fb9a547 AM |
31 | #include "pointer-set.h" |
32 | #include "tree-ssa-alias.h" | |
33 | #include "internal-fn.h" | |
34 | #include "gimple-expr.h" | |
35 | #include "is-a.h" | |
18f429e2 | 36 | #include "gimple.h" |
45b0be94 | 37 | #include "gimplify.h" |
5be5c238 | 38 | #include "gimple-iterator.h" |
442b4905 AM |
39 | #include "gimple-ssa.h" |
40 | #include "tree-cfg.h" | |
41 | #include "tree-phinodes.h" | |
42 | #include "ssa-iterators.h" | |
e28030cf AM |
43 | #include "tree-ssa-loop-ivopts.h" |
44 | #include "tree-ssa-loop-niter.h" | |
442b4905 | 45 | #include "tree-ssa-loop.h" |
7ee2468b | 46 | #include "dumpfile.h" |
e9eb809d | 47 | #include "cfgloop.h" |
e9eb809d ZD |
48 | #include "tree-chrec.h" |
49 | #include "tree-scalar-evolution.h" | |
86df10e3 | 50 | #include "tree-data-ref.h" |
e9eb809d ZD |
51 | #include "params.h" |
52 | #include "flags.h" | |
718f9c0f | 53 | #include "diagnostic-core.h" |
e9eb809d | 54 | #include "tree-inline.h" |
fbd28bc3 | 55 | #include "tree-pass.h" |
d8a2d370 | 56 | #include "stringpool.h" |
7190fdc1 | 57 | #include "tree-ssanames.h" |
807e902e | 58 | #include "wide-int-print.h" |
e9eb809d | 59 | |
71343877 | 60 | |
c22940cd | 61 | #define SWAP(X, Y) do { affine_iv *tmp = (X); (X) = (Y); (Y) = tmp; } while (0) |
e9eb809d | 62 | |
b3ce5b6e ZD |
63 | /* The maximum number of dominator BBs we search for conditions |
64 | of loop header copies we use for simplifying a conditional | |
65 | expression. */ | |
66 | #define MAX_DOMINATORS_TO_WALK 8 | |
e9eb809d ZD |
67 | |
68 | /* | |
69 | ||
70 | Analysis of number of iterations of an affine exit test. | |
71 | ||
72 | */ | |
73 | ||
b3ce5b6e ZD |
74 | /* Bounds on some value, BELOW <= X <= UP. */ |
75 | ||
76 | typedef struct | |
77 | { | |
78 | mpz_t below, up; | |
79 | } bounds; | |
80 | ||
b3ce5b6e ZD |
81 | |
82 | /* Splits expression EXPR to a variable part VAR and constant OFFSET. */ | |
83 | ||
84 | static void | |
85 | split_to_var_and_offset (tree expr, tree *var, mpz_t offset) | |
86 | { | |
87 | tree type = TREE_TYPE (expr); | |
88 | tree op0, op1; | |
b3ce5b6e ZD |
89 | bool negate = false; |
90 | ||
91 | *var = expr; | |
92 | mpz_set_ui (offset, 0); | |
93 | ||
94 | switch (TREE_CODE (expr)) | |
95 | { | |
96 | case MINUS_EXPR: | |
97 | negate = true; | |
98 | /* Fallthru. */ | |
99 | ||
100 | case PLUS_EXPR: | |
5be014d5 | 101 | case POINTER_PLUS_EXPR: |
b3ce5b6e ZD |
102 | op0 = TREE_OPERAND (expr, 0); |
103 | op1 = TREE_OPERAND (expr, 1); | |
104 | ||
105 | if (TREE_CODE (op1) != INTEGER_CST) | |
106 | break; | |
107 | ||
108 | *var = op0; | |
109 | /* Always sign extend the offset. */ | |
807e902e | 110 | wi::to_mpz (op1, offset, SIGNED); |
eab1da69 UB |
111 | if (negate) |
112 | mpz_neg (offset, offset); | |
b3ce5b6e ZD |
113 | break; |
114 | ||
115 | case INTEGER_CST: | |
116 | *var = build_int_cst_type (type, 0); | |
807e902e | 117 | wi::to_mpz (expr, offset, TYPE_SIGN (type)); |
b3ce5b6e ZD |
118 | break; |
119 | ||
120 | default: | |
121 | break; | |
122 | } | |
123 | } | |
124 | ||
125 | /* Stores estimate on the minimum/maximum value of the expression VAR + OFF | |
126 | in TYPE to MIN and MAX. */ | |
127 | ||
128 | static void | |
7190fdc1 | 129 | determine_value_range (struct loop *loop, tree type, tree var, mpz_t off, |
b3ce5b6e ZD |
130 | mpz_t min, mpz_t max) |
131 | { | |
807e902e | 132 | wide_int minv, maxv; |
7190fdc1 JJ |
133 | enum value_range_type rtype = VR_VARYING; |
134 | ||
b3ce5b6e ZD |
135 | /* If the expression is a constant, we know its value exactly. */ |
136 | if (integer_zerop (var)) | |
137 | { | |
138 | mpz_set (min, off); | |
139 | mpz_set (max, off); | |
140 | return; | |
141 | } | |
142 | ||
7190fdc1 JJ |
143 | get_type_static_bounds (type, min, max); |
144 | ||
145 | /* See if we have some range info from VRP. */ | |
146 | if (TREE_CODE (var) == SSA_NAME && INTEGRAL_TYPE_P (type)) | |
147 | { | |
148 | edge e = loop_preheader_edge (loop); | |
807e902e | 149 | signop sgn = TYPE_SIGN (type); |
7190fdc1 JJ |
150 | gimple_stmt_iterator gsi; |
151 | ||
152 | /* Either for VAR itself... */ | |
153 | rtype = get_range_info (var, &minv, &maxv); | |
154 | /* Or for PHI results in loop->header where VAR is used as | |
155 | PHI argument from the loop preheader edge. */ | |
156 | for (gsi = gsi_start_phis (loop->header); !gsi_end_p (gsi); gsi_next (&gsi)) | |
157 | { | |
158 | gimple phi = gsi_stmt (gsi); | |
807e902e | 159 | wide_int minc, maxc; |
7190fdc1 JJ |
160 | if (PHI_ARG_DEF_FROM_EDGE (phi, e) == var |
161 | && (get_range_info (gimple_phi_result (phi), &minc, &maxc) | |
162 | == VR_RANGE)) | |
163 | { | |
164 | if (rtype != VR_RANGE) | |
165 | { | |
166 | rtype = VR_RANGE; | |
167 | minv = minc; | |
168 | maxv = maxc; | |
169 | } | |
170 | else | |
171 | { | |
807e902e KZ |
172 | minv = wi::max (minv, minc, sgn); |
173 | maxv = wi::min (maxv, maxc, sgn); | |
20adc5b1 JJ |
174 | /* If the PHI result range are inconsistent with |
175 | the VAR range, give up on looking at the PHI | |
176 | results. This can happen if VR_UNDEFINED is | |
177 | involved. */ | |
807e902e | 178 | if (wi::gt_p (minv, maxv, sgn)) |
20adc5b1 JJ |
179 | { |
180 | rtype = get_range_info (var, &minv, &maxv); | |
181 | break; | |
182 | } | |
7190fdc1 JJ |
183 | } |
184 | } | |
185 | } | |
186 | if (rtype == VR_RANGE) | |
187 | { | |
188 | mpz_t minm, maxm; | |
807e902e | 189 | gcc_assert (wi::le_p (minv, maxv, sgn)); |
7190fdc1 JJ |
190 | mpz_init (minm); |
191 | mpz_init (maxm); | |
807e902e KZ |
192 | wi::to_mpz (minv, minm, sgn); |
193 | wi::to_mpz (maxv, maxm, sgn); | |
7190fdc1 JJ |
194 | mpz_add (minm, minm, off); |
195 | mpz_add (maxm, maxm, off); | |
196 | /* If the computation may not wrap or off is zero, then this | |
197 | is always fine. If off is negative and minv + off isn't | |
198 | smaller than type's minimum, or off is positive and | |
199 | maxv + off isn't bigger than type's maximum, use the more | |
200 | precise range too. */ | |
201 | if (nowrap_type_p (type) | |
202 | || mpz_sgn (off) == 0 | |
203 | || (mpz_sgn (off) < 0 && mpz_cmp (minm, min) >= 0) | |
204 | || (mpz_sgn (off) > 0 && mpz_cmp (maxm, max) <= 0)) | |
205 | { | |
206 | mpz_set (min, minm); | |
207 | mpz_set (max, maxm); | |
208 | mpz_clear (minm); | |
209 | mpz_clear (maxm); | |
210 | return; | |
211 | } | |
212 | mpz_clear (minm); | |
213 | mpz_clear (maxm); | |
214 | } | |
215 | } | |
216 | ||
b3ce5b6e ZD |
217 | /* If the computation may wrap, we know nothing about the value, except for |
218 | the range of the type. */ | |
b3ce5b6e ZD |
219 | if (!nowrap_type_p (type)) |
220 | return; | |
221 | ||
222 | /* Since the addition of OFF does not wrap, if OFF is positive, then we may | |
223 | add it to MIN, otherwise to MAX. */ | |
224 | if (mpz_sgn (off) < 0) | |
225 | mpz_add (max, max, off); | |
226 | else | |
227 | mpz_add (min, min, off); | |
228 | } | |
229 | ||
230 | /* Stores the bounds on the difference of the values of the expressions | |
231 | (var + X) and (var + Y), computed in TYPE, to BNDS. */ | |
232 | ||
233 | static void | |
234 | bound_difference_of_offsetted_base (tree type, mpz_t x, mpz_t y, | |
235 | bounds *bnds) | |
236 | { | |
237 | int rel = mpz_cmp (x, y); | |
238 | bool may_wrap = !nowrap_type_p (type); | |
239 | mpz_t m; | |
240 | ||
241 | /* If X == Y, then the expressions are always equal. | |
242 | If X > Y, there are the following possibilities: | |
243 | a) neither of var + X and var + Y overflow or underflow, or both of | |
244 | them do. Then their difference is X - Y. | |
245 | b) var + X overflows, and var + Y does not. Then the values of the | |
246 | expressions are var + X - M and var + Y, where M is the range of | |
247 | the type, and their difference is X - Y - M. | |
248 | c) var + Y underflows and var + X does not. Their difference again | |
249 | is M - X + Y. | |
250 | Therefore, if the arithmetics in type does not overflow, then the | |
251 | bounds are (X - Y, X - Y), otherwise they are (X - Y - M, X - Y) | |
252 | Similarly, if X < Y, the bounds are either (X - Y, X - Y) or | |
253 | (X - Y, X - Y + M). */ | |
254 | ||
255 | if (rel == 0) | |
256 | { | |
257 | mpz_set_ui (bnds->below, 0); | |
258 | mpz_set_ui (bnds->up, 0); | |
259 | return; | |
260 | } | |
261 | ||
262 | mpz_init (m); | |
807e902e | 263 | wi::to_mpz (wi::minus_one (TYPE_PRECISION (type)), m, UNSIGNED); |
b3ce5b6e ZD |
264 | mpz_add_ui (m, m, 1); |
265 | mpz_sub (bnds->up, x, y); | |
266 | mpz_set (bnds->below, bnds->up); | |
267 | ||
268 | if (may_wrap) | |
269 | { | |
270 | if (rel > 0) | |
271 | mpz_sub (bnds->below, bnds->below, m); | |
272 | else | |
273 | mpz_add (bnds->up, bnds->up, m); | |
274 | } | |
275 | ||
276 | mpz_clear (m); | |
277 | } | |
278 | ||
279 | /* From condition C0 CMP C1 derives information regarding the | |
280 | difference of values of VARX + OFFX and VARY + OFFY, computed in TYPE, | |
281 | and stores it to BNDS. */ | |
282 | ||
283 | static void | |
284 | refine_bounds_using_guard (tree type, tree varx, mpz_t offx, | |
285 | tree vary, mpz_t offy, | |
286 | tree c0, enum tree_code cmp, tree c1, | |
287 | bounds *bnds) | |
288 | { | |
17b236ed | 289 | tree varc0, varc1, tmp, ctype; |
b3ce5b6e ZD |
290 | mpz_t offc0, offc1, loffx, loffy, bnd; |
291 | bool lbound = false; | |
292 | bool no_wrap = nowrap_type_p (type); | |
293 | bool x_ok, y_ok; | |
294 | ||
295 | switch (cmp) | |
296 | { | |
297 | case LT_EXPR: | |
298 | case LE_EXPR: | |
299 | case GT_EXPR: | |
300 | case GE_EXPR: | |
17b236ed ZD |
301 | STRIP_SIGN_NOPS (c0); |
302 | STRIP_SIGN_NOPS (c1); | |
303 | ctype = TREE_TYPE (c0); | |
36618b93 | 304 | if (!useless_type_conversion_p (ctype, type)) |
17b236ed ZD |
305 | return; |
306 | ||
b3ce5b6e ZD |
307 | break; |
308 | ||
309 | case EQ_EXPR: | |
310 | /* We could derive quite precise information from EQ_EXPR, however, such | |
17b236ed ZD |
311 | a guard is unlikely to appear, so we do not bother with handling |
312 | it. */ | |
b3ce5b6e ZD |
313 | return; |
314 | ||
315 | case NE_EXPR: | |
17b236ed ZD |
316 | /* NE_EXPR comparisons do not contain much of useful information, except for |
317 | special case of comparing with the bounds of the type. */ | |
318 | if (TREE_CODE (c1) != INTEGER_CST | |
319 | || !INTEGRAL_TYPE_P (type)) | |
320 | return; | |
321 | ||
322 | /* Ensure that the condition speaks about an expression in the same type | |
323 | as X and Y. */ | |
324 | ctype = TREE_TYPE (c0); | |
325 | if (TYPE_PRECISION (ctype) != TYPE_PRECISION (type)) | |
326 | return; | |
327 | c0 = fold_convert (type, c0); | |
328 | c1 = fold_convert (type, c1); | |
329 | ||
330 | if (TYPE_MIN_VALUE (type) | |
331 | && operand_equal_p (c1, TYPE_MIN_VALUE (type), 0)) | |
332 | { | |
333 | cmp = GT_EXPR; | |
334 | break; | |
335 | } | |
336 | if (TYPE_MAX_VALUE (type) | |
337 | && operand_equal_p (c1, TYPE_MAX_VALUE (type), 0)) | |
338 | { | |
339 | cmp = LT_EXPR; | |
340 | break; | |
341 | } | |
342 | ||
b3ce5b6e ZD |
343 | return; |
344 | default: | |
345 | return; | |
b8698a0f | 346 | } |
b3ce5b6e ZD |
347 | |
348 | mpz_init (offc0); | |
349 | mpz_init (offc1); | |
350 | split_to_var_and_offset (expand_simple_operations (c0), &varc0, offc0); | |
351 | split_to_var_and_offset (expand_simple_operations (c1), &varc1, offc1); | |
352 | ||
353 | /* We are only interested in comparisons of expressions based on VARX and | |
354 | VARY. TODO -- we might also be able to derive some bounds from | |
355 | expressions containing just one of the variables. */ | |
356 | ||
357 | if (operand_equal_p (varx, varc1, 0)) | |
358 | { | |
359 | tmp = varc0; varc0 = varc1; varc1 = tmp; | |
360 | mpz_swap (offc0, offc1); | |
361 | cmp = swap_tree_comparison (cmp); | |
362 | } | |
363 | ||
364 | if (!operand_equal_p (varx, varc0, 0) | |
365 | || !operand_equal_p (vary, varc1, 0)) | |
366 | goto end; | |
367 | ||
368 | mpz_init_set (loffx, offx); | |
369 | mpz_init_set (loffy, offy); | |
370 | ||
371 | if (cmp == GT_EXPR || cmp == GE_EXPR) | |
372 | { | |
373 | tmp = varx; varx = vary; vary = tmp; | |
374 | mpz_swap (offc0, offc1); | |
375 | mpz_swap (loffx, loffy); | |
376 | cmp = swap_tree_comparison (cmp); | |
377 | lbound = true; | |
378 | } | |
379 | ||
380 | /* If there is no overflow, the condition implies that | |
381 | ||
382 | (VARX + OFFX) cmp (VARY + OFFY) + (OFFX - OFFY + OFFC1 - OFFC0). | |
383 | ||
384 | The overflows and underflows may complicate things a bit; each | |
385 | overflow decreases the appropriate offset by M, and underflow | |
386 | increases it by M. The above inequality would not necessarily be | |
387 | true if | |
b8698a0f | 388 | |
b3ce5b6e ZD |
389 | -- VARX + OFFX underflows and VARX + OFFC0 does not, or |
390 | VARX + OFFC0 overflows, but VARX + OFFX does not. | |
391 | This may only happen if OFFX < OFFC0. | |
392 | -- VARY + OFFY overflows and VARY + OFFC1 does not, or | |
393 | VARY + OFFC1 underflows and VARY + OFFY does not. | |
394 | This may only happen if OFFY > OFFC1. */ | |
395 | ||
396 | if (no_wrap) | |
397 | { | |
398 | x_ok = true; | |
399 | y_ok = true; | |
400 | } | |
401 | else | |
402 | { | |
403 | x_ok = (integer_zerop (varx) | |
404 | || mpz_cmp (loffx, offc0) >= 0); | |
405 | y_ok = (integer_zerop (vary) | |
406 | || mpz_cmp (loffy, offc1) <= 0); | |
407 | } | |
408 | ||
409 | if (x_ok && y_ok) | |
410 | { | |
411 | mpz_init (bnd); | |
412 | mpz_sub (bnd, loffx, loffy); | |
413 | mpz_add (bnd, bnd, offc1); | |
414 | mpz_sub (bnd, bnd, offc0); | |
415 | ||
416 | if (cmp == LT_EXPR) | |
417 | mpz_sub_ui (bnd, bnd, 1); | |
418 | ||
419 | if (lbound) | |
420 | { | |
421 | mpz_neg (bnd, bnd); | |
422 | if (mpz_cmp (bnds->below, bnd) < 0) | |
423 | mpz_set (bnds->below, bnd); | |
424 | } | |
425 | else | |
426 | { | |
427 | if (mpz_cmp (bnd, bnds->up) < 0) | |
428 | mpz_set (bnds->up, bnd); | |
429 | } | |
430 | mpz_clear (bnd); | |
431 | } | |
432 | ||
433 | mpz_clear (loffx); | |
434 | mpz_clear (loffy); | |
435 | end: | |
436 | mpz_clear (offc0); | |
437 | mpz_clear (offc1); | |
438 | } | |
439 | ||
440 | /* Stores the bounds on the value of the expression X - Y in LOOP to BNDS. | |
441 | The subtraction is considered to be performed in arbitrary precision, | |
442 | without overflows. | |
b8698a0f | 443 | |
b3ce5b6e ZD |
444 | We do not attempt to be too clever regarding the value ranges of X and |
445 | Y; most of the time, they are just integers or ssa names offsetted by | |
446 | integer. However, we try to use the information contained in the | |
447 | comparisons before the loop (usually created by loop header copying). */ | |
448 | ||
449 | static void | |
450 | bound_difference (struct loop *loop, tree x, tree y, bounds *bnds) | |
451 | { | |
452 | tree type = TREE_TYPE (x); | |
453 | tree varx, vary; | |
454 | mpz_t offx, offy; | |
455 | mpz_t minx, maxx, miny, maxy; | |
456 | int cnt = 0; | |
457 | edge e; | |
458 | basic_block bb; | |
726a989a RB |
459 | tree c0, c1; |
460 | gimple cond; | |
b3ce5b6e ZD |
461 | enum tree_code cmp; |
462 | ||
17b236ed ZD |
463 | /* Get rid of unnecessary casts, but preserve the value of |
464 | the expressions. */ | |
465 | STRIP_SIGN_NOPS (x); | |
466 | STRIP_SIGN_NOPS (y); | |
467 | ||
b3ce5b6e ZD |
468 | mpz_init (bnds->below); |
469 | mpz_init (bnds->up); | |
470 | mpz_init (offx); | |
471 | mpz_init (offy); | |
472 | split_to_var_and_offset (x, &varx, offx); | |
473 | split_to_var_and_offset (y, &vary, offy); | |
474 | ||
475 | if (!integer_zerop (varx) | |
476 | && operand_equal_p (varx, vary, 0)) | |
477 | { | |
478 | /* Special case VARX == VARY -- we just need to compare the | |
479 | offsets. The matters are a bit more complicated in the | |
480 | case addition of offsets may wrap. */ | |
481 | bound_difference_of_offsetted_base (type, offx, offy, bnds); | |
482 | } | |
483 | else | |
484 | { | |
485 | /* Otherwise, use the value ranges to determine the initial | |
486 | estimates on below and up. */ | |
487 | mpz_init (minx); | |
488 | mpz_init (maxx); | |
489 | mpz_init (miny); | |
490 | mpz_init (maxy); | |
7190fdc1 JJ |
491 | determine_value_range (loop, type, varx, offx, minx, maxx); |
492 | determine_value_range (loop, type, vary, offy, miny, maxy); | |
b3ce5b6e ZD |
493 | |
494 | mpz_sub (bnds->below, minx, maxy); | |
495 | mpz_sub (bnds->up, maxx, miny); | |
496 | mpz_clear (minx); | |
497 | mpz_clear (maxx); | |
498 | mpz_clear (miny); | |
499 | mpz_clear (maxy); | |
500 | } | |
501 | ||
502 | /* If both X and Y are constants, we cannot get any more precise. */ | |
503 | if (integer_zerop (varx) && integer_zerop (vary)) | |
504 | goto end; | |
505 | ||
506 | /* Now walk the dominators of the loop header and use the entry | |
507 | guards to refine the estimates. */ | |
508 | for (bb = loop->header; | |
fefa31b5 | 509 | bb != ENTRY_BLOCK_PTR_FOR_FN (cfun) && cnt < MAX_DOMINATORS_TO_WALK; |
b3ce5b6e ZD |
510 | bb = get_immediate_dominator (CDI_DOMINATORS, bb)) |
511 | { | |
512 | if (!single_pred_p (bb)) | |
513 | continue; | |
514 | e = single_pred_edge (bb); | |
515 | ||
516 | if (!(e->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
517 | continue; | |
518 | ||
726a989a RB |
519 | cond = last_stmt (e->src); |
520 | c0 = gimple_cond_lhs (cond); | |
521 | cmp = gimple_cond_code (cond); | |
522 | c1 = gimple_cond_rhs (cond); | |
b3ce5b6e ZD |
523 | |
524 | if (e->flags & EDGE_FALSE_VALUE) | |
525 | cmp = invert_tree_comparison (cmp, false); | |
526 | ||
527 | refine_bounds_using_guard (type, varx, offx, vary, offy, | |
528 | c0, cmp, c1, bnds); | |
529 | ++cnt; | |
530 | } | |
531 | ||
532 | end: | |
533 | mpz_clear (offx); | |
534 | mpz_clear (offy); | |
535 | } | |
536 | ||
537 | /* Update the bounds in BNDS that restrict the value of X to the bounds | |
538 | that restrict the value of X + DELTA. X can be obtained as a | |
539 | difference of two values in TYPE. */ | |
540 | ||
541 | static void | |
807e902e | 542 | bounds_add (bounds *bnds, const widest_int &delta, tree type) |
b3ce5b6e ZD |
543 | { |
544 | mpz_t mdelta, max; | |
545 | ||
546 | mpz_init (mdelta); | |
807e902e | 547 | wi::to_mpz (delta, mdelta, SIGNED); |
b3ce5b6e ZD |
548 | |
549 | mpz_init (max); | |
807e902e | 550 | wi::to_mpz (wi::minus_one (TYPE_PRECISION (type)), max, UNSIGNED); |
b3ce5b6e ZD |
551 | |
552 | mpz_add (bnds->up, bnds->up, mdelta); | |
553 | mpz_add (bnds->below, bnds->below, mdelta); | |
554 | ||
555 | if (mpz_cmp (bnds->up, max) > 0) | |
556 | mpz_set (bnds->up, max); | |
557 | ||
558 | mpz_neg (max, max); | |
559 | if (mpz_cmp (bnds->below, max) < 0) | |
560 | mpz_set (bnds->below, max); | |
561 | ||
562 | mpz_clear (mdelta); | |
563 | mpz_clear (max); | |
564 | } | |
565 | ||
566 | /* Update the bounds in BNDS that restrict the value of X to the bounds | |
567 | that restrict the value of -X. */ | |
568 | ||
569 | static void | |
570 | bounds_negate (bounds *bnds) | |
571 | { | |
572 | mpz_t tmp; | |
573 | ||
574 | mpz_init_set (tmp, bnds->up); | |
575 | mpz_neg (bnds->up, bnds->below); | |
576 | mpz_neg (bnds->below, tmp); | |
577 | mpz_clear (tmp); | |
578 | } | |
579 | ||
e9eb809d ZD |
580 | /* Returns inverse of X modulo 2^s, where MASK = 2^s-1. */ |
581 | ||
582 | static tree | |
583 | inverse (tree x, tree mask) | |
584 | { | |
585 | tree type = TREE_TYPE (x); | |
26630a99 ZD |
586 | tree rslt; |
587 | unsigned ctr = tree_floor_log2 (mask); | |
588 | ||
589 | if (TYPE_PRECISION (type) <= HOST_BITS_PER_WIDE_INT) | |
590 | { | |
591 | unsigned HOST_WIDE_INT ix; | |
592 | unsigned HOST_WIDE_INT imask; | |
593 | unsigned HOST_WIDE_INT irslt = 1; | |
594 | ||
595 | gcc_assert (cst_and_fits_in_hwi (x)); | |
596 | gcc_assert (cst_and_fits_in_hwi (mask)); | |
597 | ||
598 | ix = int_cst_value (x); | |
599 | imask = int_cst_value (mask); | |
600 | ||
601 | for (; ctr; ctr--) | |
602 | { | |
603 | irslt *= ix; | |
604 | ix *= ix; | |
605 | } | |
606 | irslt &= imask; | |
e9eb809d | 607 | |
26630a99 ZD |
608 | rslt = build_int_cst_type (type, irslt); |
609 | } | |
610 | else | |
e9eb809d | 611 | { |
ff5e9a94 | 612 | rslt = build_int_cst (type, 1); |
26630a99 ZD |
613 | for (; ctr; ctr--) |
614 | { | |
d35936ab RG |
615 | rslt = int_const_binop (MULT_EXPR, rslt, x); |
616 | x = int_const_binop (MULT_EXPR, x, x); | |
26630a99 | 617 | } |
d35936ab | 618 | rslt = int_const_binop (BIT_AND_EXPR, rslt, mask); |
e9eb809d ZD |
619 | } |
620 | ||
621 | return rslt; | |
622 | } | |
623 | ||
b3ce5b6e | 624 | /* Derives the upper bound BND on the number of executions of loop with exit |
1987baa3 ZD |
625 | condition S * i <> C. If NO_OVERFLOW is true, then the control variable of |
626 | the loop does not overflow. EXIT_MUST_BE_TAKEN is true if we are guaranteed | |
627 | that the loop ends through this exit, i.e., the induction variable ever | |
628 | reaches the value of C. | |
629 | ||
630 | The value C is equal to final - base, where final and base are the final and | |
631 | initial value of the actual induction variable in the analysed loop. BNDS | |
632 | bounds the value of this difference when computed in signed type with | |
633 | unbounded range, while the computation of C is performed in an unsigned | |
634 | type with the range matching the range of the type of the induction variable. | |
635 | In particular, BNDS.up contains an upper bound on C in the following cases: | |
636 | -- if the iv must reach its final value without overflow, i.e., if | |
637 | NO_OVERFLOW && EXIT_MUST_BE_TAKEN is true, or | |
638 | -- if final >= base, which we know to hold when BNDS.below >= 0. */ | |
b3ce5b6e ZD |
639 | |
640 | static void | |
641 | number_of_iterations_ne_max (mpz_t bnd, bool no_overflow, tree c, tree s, | |
1987baa3 | 642 | bounds *bnds, bool exit_must_be_taken) |
b3ce5b6e | 643 | { |
807e902e | 644 | widest_int max; |
b3ce5b6e | 645 | mpz_t d; |
5a892248 | 646 | tree type = TREE_TYPE (c); |
1987baa3 ZD |
647 | bool bnds_u_valid = ((no_overflow && exit_must_be_taken) |
648 | || mpz_sgn (bnds->below) >= 0); | |
b3ce5b6e | 649 | |
5a892248 RB |
650 | if (integer_onep (s) |
651 | || (TREE_CODE (c) == INTEGER_CST | |
652 | && TREE_CODE (s) == INTEGER_CST | |
807e902e KZ |
653 | && wi::mod_trunc (c, s, TYPE_SIGN (type)) == 0) |
654 | || (TYPE_OVERFLOW_UNDEFINED (type) | |
5a892248 | 655 | && multiple_of_p (type, c, s))) |
1987baa3 ZD |
656 | { |
657 | /* If C is an exact multiple of S, then its value will be reached before | |
658 | the induction variable overflows (unless the loop is exited in some | |
659 | other way before). Note that the actual induction variable in the | |
660 | loop (which ranges from base to final instead of from 0 to C) may | |
661 | overflow, in which case BNDS.up will not be giving a correct upper | |
662 | bound on C; thus, BNDS_U_VALID had to be computed in advance. */ | |
663 | no_overflow = true; | |
664 | exit_must_be_taken = true; | |
665 | } | |
666 | ||
667 | /* If the induction variable can overflow, the number of iterations is at | |
668 | most the period of the control variable (or infinite, but in that case | |
669 | the whole # of iterations analysis will fail). */ | |
670 | if (!no_overflow) | |
b3ce5b6e | 671 | { |
807e902e KZ |
672 | max = wi::mask <widest_int> (TYPE_PRECISION (type) - wi::ctz (s), false); |
673 | wi::to_mpz (max, bnd, UNSIGNED); | |
b3ce5b6e ZD |
674 | return; |
675 | } | |
676 | ||
1987baa3 ZD |
677 | /* Now we know that the induction variable does not overflow, so the loop |
678 | iterates at most (range of type / S) times. */ | |
807e902e | 679 | wi::to_mpz (wi::minus_one (TYPE_PRECISION (type)), bnd, UNSIGNED); |
1987baa3 ZD |
680 | |
681 | /* If the induction variable is guaranteed to reach the value of C before | |
682 | overflow, ... */ | |
683 | if (exit_must_be_taken) | |
684 | { | |
073a8998 | 685 | /* ... then we can strengthen this to C / S, and possibly we can use |
1987baa3 ZD |
686 | the upper bound on C given by BNDS. */ |
687 | if (TREE_CODE (c) == INTEGER_CST) | |
807e902e | 688 | wi::to_mpz (c, bnd, UNSIGNED); |
1987baa3 ZD |
689 | else if (bnds_u_valid) |
690 | mpz_set (bnd, bnds->up); | |
691 | } | |
b3ce5b6e ZD |
692 | |
693 | mpz_init (d); | |
807e902e | 694 | wi::to_mpz (s, d, UNSIGNED); |
b3ce5b6e ZD |
695 | mpz_fdiv_q (bnd, bnd, d); |
696 | mpz_clear (d); | |
697 | } | |
698 | ||
7f17528a ZD |
699 | /* Determines number of iterations of loop whose ending condition |
700 | is IV <> FINAL. TYPE is the type of the iv. The number of | |
e36dc339 | 701 | iterations is stored to NITER. EXIT_MUST_BE_TAKEN is true if |
f08ac361 ZD |
702 | we know that the exit must be taken eventually, i.e., that the IV |
703 | ever reaches the value FINAL (we derived this earlier, and possibly set | |
b3ce5b6e ZD |
704 | NITER->assumptions to make sure this is the case). BNDS contains the |
705 | bounds on the difference FINAL - IV->base. */ | |
e9eb809d | 706 | |
7f17528a ZD |
707 | static bool |
708 | number_of_iterations_ne (tree type, affine_iv *iv, tree final, | |
e36dc339 | 709 | struct tree_niter_desc *niter, bool exit_must_be_taken, |
b3ce5b6e | 710 | bounds *bnds) |
e9eb809d | 711 | { |
7f17528a ZD |
712 | tree niter_type = unsigned_type_for (type); |
713 | tree s, c, d, bits, assumption, tmp, bound; | |
b3ce5b6e | 714 | mpz_t max; |
e9eb809d | 715 | |
17684618 ZD |
716 | niter->control = *iv; |
717 | niter->bound = final; | |
718 | niter->cmp = NE_EXPR; | |
719 | ||
b3ce5b6e ZD |
720 | /* Rearrange the terms so that we get inequality S * i <> C, with S |
721 | positive. Also cast everything to the unsigned type. If IV does | |
722 | not overflow, BNDS bounds the value of C. Also, this is the | |
723 | case if the computation |FINAL - IV->base| does not overflow, i.e., | |
724 | if BNDS->below in the result is nonnegative. */ | |
7f17528a | 725 | if (tree_int_cst_sign_bit (iv->step)) |
e9eb809d | 726 | { |
7f17528a ZD |
727 | s = fold_convert (niter_type, |
728 | fold_build1 (NEGATE_EXPR, type, iv->step)); | |
729 | c = fold_build2 (MINUS_EXPR, niter_type, | |
730 | fold_convert (niter_type, iv->base), | |
731 | fold_convert (niter_type, final)); | |
b3ce5b6e | 732 | bounds_negate (bnds); |
e9eb809d | 733 | } |
a6f778b2 | 734 | else |
e9eb809d | 735 | { |
7f17528a ZD |
736 | s = fold_convert (niter_type, iv->step); |
737 | c = fold_build2 (MINUS_EXPR, niter_type, | |
738 | fold_convert (niter_type, final), | |
739 | fold_convert (niter_type, iv->base)); | |
740 | } | |
e9eb809d | 741 | |
b3ce5b6e | 742 | mpz_init (max); |
1987baa3 ZD |
743 | number_of_iterations_ne_max (max, iv->no_overflow, c, s, bnds, |
744 | exit_must_be_taken); | |
807e902e KZ |
745 | niter->max = widest_int::from (wi::from_mpz (niter_type, max, false), |
746 | TYPE_SIGN (niter_type)); | |
b3ce5b6e ZD |
747 | mpz_clear (max); |
748 | ||
7f17528a ZD |
749 | /* First the trivial cases -- when the step is 1. */ |
750 | if (integer_onep (s)) | |
751 | { | |
752 | niter->niter = c; | |
753 | return true; | |
e9eb809d ZD |
754 | } |
755 | ||
7f17528a ZD |
756 | /* Let nsd (step, size of mode) = d. If d does not divide c, the loop |
757 | is infinite. Otherwise, the number of iterations is | |
758 | (inverse(s/d) * (c/d)) mod (size of mode/d). */ | |
759 | bits = num_ending_zeros (s); | |
760 | bound = build_low_bits_mask (niter_type, | |
761 | (TYPE_PRECISION (niter_type) | |
ae7e9ddd | 762 | - tree_to_uhwi (bits))); |
e9eb809d | 763 | |
7f17528a | 764 | d = fold_binary_to_constant (LSHIFT_EXPR, niter_type, |
ff5e9a94 | 765 | build_int_cst (niter_type, 1), bits); |
7f17528a | 766 | s = fold_binary_to_constant (RSHIFT_EXPR, niter_type, s, bits); |
e9eb809d | 767 | |
e36dc339 | 768 | if (!exit_must_be_taken) |
7f17528a | 769 | { |
e36dc339 | 770 | /* If we cannot assume that the exit is taken eventually, record the |
7f17528a ZD |
771 | assumptions for divisibility of c. */ |
772 | assumption = fold_build2 (FLOOR_MOD_EXPR, niter_type, c, d); | |
773 | assumption = fold_build2 (EQ_EXPR, boolean_type_node, | |
774 | assumption, build_int_cst (niter_type, 0)); | |
6e682d7e | 775 | if (!integer_nonzerop (assumption)) |
7f17528a ZD |
776 | niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, |
777 | niter->assumptions, assumption); | |
e9eb809d | 778 | } |
b8698a0f | 779 | |
7f17528a ZD |
780 | c = fold_build2 (EXACT_DIV_EXPR, niter_type, c, d); |
781 | tmp = fold_build2 (MULT_EXPR, niter_type, c, inverse (s, bound)); | |
782 | niter->niter = fold_build2 (BIT_AND_EXPR, niter_type, tmp, bound); | |
783 | return true; | |
784 | } | |
e9eb809d | 785 | |
7f17528a ZD |
786 | /* Checks whether we can determine the final value of the control variable |
787 | of the loop with ending condition IV0 < IV1 (computed in TYPE). | |
788 | DELTA is the difference IV1->base - IV0->base, STEP is the absolute value | |
789 | of the step. The assumptions necessary to ensure that the computation | |
790 | of the final value does not overflow are recorded in NITER. If we | |
791 | find the final value, we adjust DELTA and return TRUE. Otherwise | |
b3ce5b6e | 792 | we return false. BNDS bounds the value of IV1->base - IV0->base, |
e36dc339 ZD |
793 | and will be updated by the same amount as DELTA. EXIT_MUST_BE_TAKEN is |
794 | true if we know that the exit must be taken eventually. */ | |
7f17528a ZD |
795 | |
796 | static bool | |
797 | number_of_iterations_lt_to_ne (tree type, affine_iv *iv0, affine_iv *iv1, | |
798 | struct tree_niter_desc *niter, | |
b3ce5b6e | 799 | tree *delta, tree step, |
e36dc339 | 800 | bool exit_must_be_taken, bounds *bnds) |
7f17528a ZD |
801 | { |
802 | tree niter_type = TREE_TYPE (step); | |
803 | tree mod = fold_build2 (FLOOR_MOD_EXPR, niter_type, *delta, step); | |
804 | tree tmod; | |
b3ce5b6e | 805 | mpz_t mmod; |
7f17528a | 806 | tree assumption = boolean_true_node, bound, noloop; |
e36dc339 | 807 | bool ret = false, fv_comp_no_overflow; |
5be014d5 AP |
808 | tree type1 = type; |
809 | if (POINTER_TYPE_P (type)) | |
810 | type1 = sizetype; | |
7f17528a ZD |
811 | |
812 | if (TREE_CODE (mod) != INTEGER_CST) | |
813 | return false; | |
6e682d7e | 814 | if (integer_nonzerop (mod)) |
7f17528a | 815 | mod = fold_build2 (MINUS_EXPR, niter_type, step, mod); |
5be014d5 | 816 | tmod = fold_convert (type1, mod); |
7f17528a | 817 | |
b3ce5b6e | 818 | mpz_init (mmod); |
807e902e | 819 | wi::to_mpz (mod, mmod, UNSIGNED); |
b3ce5b6e ZD |
820 | mpz_neg (mmod, mmod); |
821 | ||
e36dc339 ZD |
822 | /* If the induction variable does not overflow and the exit is taken, |
823 | then the computation of the final value does not overflow. This is | |
824 | also obviously the case if the new final value is equal to the | |
825 | current one. Finally, we postulate this for pointer type variables, | |
826 | as the code cannot rely on the object to that the pointer points being | |
827 | placed at the end of the address space (and more pragmatically, | |
828 | TYPE_{MIN,MAX}_VALUE is not defined for pointers). */ | |
829 | if (integer_zerop (mod) || POINTER_TYPE_P (type)) | |
830 | fv_comp_no_overflow = true; | |
831 | else if (!exit_must_be_taken) | |
832 | fv_comp_no_overflow = false; | |
833 | else | |
834 | fv_comp_no_overflow = | |
835 | (iv0->no_overflow && integer_nonzerop (iv0->step)) | |
836 | || (iv1->no_overflow && integer_nonzerop (iv1->step)); | |
837 | ||
6e42ce54 | 838 | if (integer_nonzerop (iv0->step)) |
e9eb809d | 839 | { |
7f17528a ZD |
840 | /* The final value of the iv is iv1->base + MOD, assuming that this |
841 | computation does not overflow, and that | |
842 | iv0->base <= iv1->base + MOD. */ | |
e36dc339 | 843 | if (!fv_comp_no_overflow) |
7f17528a | 844 | { |
97b4ba9f | 845 | bound = fold_build2 (MINUS_EXPR, type1, |
5be014d5 | 846 | TYPE_MAX_VALUE (type1), tmod); |
7f17528a ZD |
847 | assumption = fold_build2 (LE_EXPR, boolean_type_node, |
848 | iv1->base, bound); | |
6e682d7e | 849 | if (integer_zerop (assumption)) |
b3ce5b6e | 850 | goto end; |
7f17528a | 851 | } |
b3ce5b6e ZD |
852 | if (mpz_cmp (mmod, bnds->below) < 0) |
853 | noloop = boolean_false_node; | |
97b4ba9f JJ |
854 | else if (POINTER_TYPE_P (type)) |
855 | noloop = fold_build2 (GT_EXPR, boolean_type_node, | |
856 | iv0->base, | |
5d49b6a7 | 857 | fold_build_pointer_plus (iv1->base, tmod)); |
b3ce5b6e ZD |
858 | else |
859 | noloop = fold_build2 (GT_EXPR, boolean_type_node, | |
860 | iv0->base, | |
5be014d5 | 861 | fold_build2 (PLUS_EXPR, type1, |
b3ce5b6e | 862 | iv1->base, tmod)); |
e9eb809d ZD |
863 | } |
864 | else | |
865 | { | |
7f17528a ZD |
866 | /* The final value of the iv is iv0->base - MOD, assuming that this |
867 | computation does not overflow, and that | |
868 | iv0->base - MOD <= iv1->base. */ | |
e36dc339 | 869 | if (!fv_comp_no_overflow) |
7f17528a | 870 | { |
5be014d5 AP |
871 | bound = fold_build2 (PLUS_EXPR, type1, |
872 | TYPE_MIN_VALUE (type1), tmod); | |
7f17528a ZD |
873 | assumption = fold_build2 (GE_EXPR, boolean_type_node, |
874 | iv0->base, bound); | |
6e682d7e | 875 | if (integer_zerop (assumption)) |
b3ce5b6e | 876 | goto end; |
7f17528a | 877 | } |
b3ce5b6e ZD |
878 | if (mpz_cmp (mmod, bnds->below) < 0) |
879 | noloop = boolean_false_node; | |
97b4ba9f JJ |
880 | else if (POINTER_TYPE_P (type)) |
881 | noloop = fold_build2 (GT_EXPR, boolean_type_node, | |
5d49b6a7 RG |
882 | fold_build_pointer_plus (iv0->base, |
883 | fold_build1 (NEGATE_EXPR, | |
884 | type1, tmod)), | |
97b4ba9f | 885 | iv1->base); |
b3ce5b6e ZD |
886 | else |
887 | noloop = fold_build2 (GT_EXPR, boolean_type_node, | |
5be014d5 | 888 | fold_build2 (MINUS_EXPR, type1, |
b3ce5b6e ZD |
889 | iv0->base, tmod), |
890 | iv1->base); | |
e9eb809d ZD |
891 | } |
892 | ||
6e682d7e | 893 | if (!integer_nonzerop (assumption)) |
7f17528a ZD |
894 | niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, |
895 | niter->assumptions, | |
896 | assumption); | |
6e682d7e | 897 | if (!integer_zerop (noloop)) |
7f17528a ZD |
898 | niter->may_be_zero = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, |
899 | niter->may_be_zero, | |
900 | noloop); | |
807e902e | 901 | bounds_add (bnds, wi::to_widest (mod), type); |
7f17528a | 902 | *delta = fold_build2 (PLUS_EXPR, niter_type, *delta, mod); |
b3ce5b6e ZD |
903 | |
904 | ret = true; | |
905 | end: | |
906 | mpz_clear (mmod); | |
907 | return ret; | |
7f17528a ZD |
908 | } |
909 | ||
910 | /* Add assertions to NITER that ensure that the control variable of the loop | |
911 | with ending condition IV0 < IV1 does not overflow. Types of IV0 and IV1 | |
912 | are TYPE. Returns false if we can prove that there is an overflow, true | |
913 | otherwise. STEP is the absolute value of the step. */ | |
e9eb809d | 914 | |
7f17528a ZD |
915 | static bool |
916 | assert_no_overflow_lt (tree type, affine_iv *iv0, affine_iv *iv1, | |
917 | struct tree_niter_desc *niter, tree step) | |
918 | { | |
919 | tree bound, d, assumption, diff; | |
920 | tree niter_type = TREE_TYPE (step); | |
921 | ||
6e42ce54 | 922 | if (integer_nonzerop (iv0->step)) |
e9eb809d | 923 | { |
7f17528a ZD |
924 | /* for (i = iv0->base; i < iv1->base; i += iv0->step) */ |
925 | if (iv0->no_overflow) | |
926 | return true; | |
927 | ||
928 | /* If iv0->base is a constant, we can determine the last value before | |
929 | overflow precisely; otherwise we conservatively assume | |
930 | MAX - STEP + 1. */ | |
931 | ||
932 | if (TREE_CODE (iv0->base) == INTEGER_CST) | |
e9eb809d | 933 | { |
7f17528a ZD |
934 | d = fold_build2 (MINUS_EXPR, niter_type, |
935 | fold_convert (niter_type, TYPE_MAX_VALUE (type)), | |
936 | fold_convert (niter_type, iv0->base)); | |
937 | diff = fold_build2 (FLOOR_MOD_EXPR, niter_type, d, step); | |
e9eb809d ZD |
938 | } |
939 | else | |
7f17528a | 940 | diff = fold_build2 (MINUS_EXPR, niter_type, step, |
ff5e9a94 | 941 | build_int_cst (niter_type, 1)); |
7f17528a ZD |
942 | bound = fold_build2 (MINUS_EXPR, type, |
943 | TYPE_MAX_VALUE (type), fold_convert (type, diff)); | |
944 | assumption = fold_build2 (LE_EXPR, boolean_type_node, | |
945 | iv1->base, bound); | |
946 | } | |
947 | else | |
948 | { | |
949 | /* for (i = iv1->base; i > iv0->base; i += iv1->step) */ | |
950 | if (iv1->no_overflow) | |
951 | return true; | |
952 | ||
953 | if (TREE_CODE (iv1->base) == INTEGER_CST) | |
e9eb809d | 954 | { |
7f17528a ZD |
955 | d = fold_build2 (MINUS_EXPR, niter_type, |
956 | fold_convert (niter_type, iv1->base), | |
957 | fold_convert (niter_type, TYPE_MIN_VALUE (type))); | |
958 | diff = fold_build2 (FLOOR_MOD_EXPR, niter_type, d, step); | |
e9eb809d | 959 | } |
7f17528a ZD |
960 | else |
961 | diff = fold_build2 (MINUS_EXPR, niter_type, step, | |
ff5e9a94 | 962 | build_int_cst (niter_type, 1)); |
7f17528a ZD |
963 | bound = fold_build2 (PLUS_EXPR, type, |
964 | TYPE_MIN_VALUE (type), fold_convert (type, diff)); | |
965 | assumption = fold_build2 (GE_EXPR, boolean_type_node, | |
966 | iv0->base, bound); | |
e9eb809d ZD |
967 | } |
968 | ||
6e682d7e | 969 | if (integer_zerop (assumption)) |
7f17528a | 970 | return false; |
6e682d7e | 971 | if (!integer_nonzerop (assumption)) |
7f17528a ZD |
972 | niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, |
973 | niter->assumptions, assumption); | |
b8698a0f | 974 | |
7f17528a ZD |
975 | iv0->no_overflow = true; |
976 | iv1->no_overflow = true; | |
977 | return true; | |
978 | } | |
e9eb809d | 979 | |
7f17528a | 980 | /* Add an assumption to NITER that a loop whose ending condition |
b3ce5b6e ZD |
981 | is IV0 < IV1 rolls. TYPE is the type of the control iv. BNDS |
982 | bounds the value of IV1->base - IV0->base. */ | |
7f17528a ZD |
983 | |
984 | static void | |
985 | assert_loop_rolls_lt (tree type, affine_iv *iv0, affine_iv *iv1, | |
b3ce5b6e | 986 | struct tree_niter_desc *niter, bounds *bnds) |
7f17528a ZD |
987 | { |
988 | tree assumption = boolean_true_node, bound, diff; | |
5be014d5 | 989 | tree mbz, mbzl, mbzr, type1; |
b3ce5b6e | 990 | bool rolls_p, no_overflow_p; |
807e902e | 991 | widest_int dstep; |
b3ce5b6e ZD |
992 | mpz_t mstep, max; |
993 | ||
994 | /* We are going to compute the number of iterations as | |
995 | (iv1->base - iv0->base + step - 1) / step, computed in the unsigned | |
b8698a0f L |
996 | variant of TYPE. This formula only works if |
997 | ||
b3ce5b6e | 998 | -step + 1 <= (iv1->base - iv0->base) <= MAX - step + 1 |
b8698a0f | 999 | |
b3ce5b6e | 1000 | (where MAX is the maximum value of the unsigned variant of TYPE, and |
072edf07 SP |
1001 | the computations in this formula are performed in full precision, |
1002 | i.e., without overflows). | |
b3ce5b6e ZD |
1003 | |
1004 | Usually, for loops with exit condition iv0->base + step * i < iv1->base, | |
072edf07 | 1005 | we have a condition of the form iv0->base - step < iv1->base before the loop, |
b3ce5b6e ZD |
1006 | and for loops iv0->base < iv1->base - step * i the condition |
1007 | iv0->base < iv1->base + step, due to loop header copying, which enable us | |
1008 | to prove the lower bound. | |
b8698a0f | 1009 | |
b3ce5b6e ZD |
1010 | The upper bound is more complicated. Unless the expressions for initial |
1011 | and final value themselves contain enough information, we usually cannot | |
1012 | derive it from the context. */ | |
1013 | ||
1014 | /* First check whether the answer does not follow from the bounds we gathered | |
1015 | before. */ | |
1016 | if (integer_nonzerop (iv0->step)) | |
807e902e | 1017 | dstep = wi::to_widest (iv0->step); |
b3ce5b6e ZD |
1018 | else |
1019 | { | |
807e902e | 1020 | dstep = wi::sext (wi::to_widest (iv1->step), TYPE_PRECISION (type)); |
27bcd47c | 1021 | dstep = -dstep; |
b3ce5b6e ZD |
1022 | } |
1023 | ||
1024 | mpz_init (mstep); | |
807e902e | 1025 | wi::to_mpz (dstep, mstep, UNSIGNED); |
b3ce5b6e ZD |
1026 | mpz_neg (mstep, mstep); |
1027 | mpz_add_ui (mstep, mstep, 1); | |
1028 | ||
1029 | rolls_p = mpz_cmp (mstep, bnds->below) <= 0; | |
1030 | ||
1031 | mpz_init (max); | |
807e902e | 1032 | wi::to_mpz (wi::minus_one (TYPE_PRECISION (type)), max, UNSIGNED); |
b3ce5b6e ZD |
1033 | mpz_add (max, max, mstep); |
1034 | no_overflow_p = (mpz_cmp (bnds->up, max) <= 0 | |
1035 | /* For pointers, only values lying inside a single object | |
1036 | can be compared or manipulated by pointer arithmetics. | |
1037 | Gcc in general does not allow or handle objects larger | |
1038 | than half of the address space, hence the upper bound | |
1039 | is satisfied for pointers. */ | |
1040 | || POINTER_TYPE_P (type)); | |
1041 | mpz_clear (mstep); | |
1042 | mpz_clear (max); | |
1043 | ||
1044 | if (rolls_p && no_overflow_p) | |
1045 | return; | |
b8698a0f | 1046 | |
5be014d5 AP |
1047 | type1 = type; |
1048 | if (POINTER_TYPE_P (type)) | |
1049 | type1 = sizetype; | |
b3ce5b6e ZD |
1050 | |
1051 | /* Now the hard part; we must formulate the assumption(s) as expressions, and | |
1052 | we must be careful not to introduce overflow. */ | |
7f17528a | 1053 | |
6e42ce54 | 1054 | if (integer_nonzerop (iv0->step)) |
e9eb809d | 1055 | { |
5be014d5 AP |
1056 | diff = fold_build2 (MINUS_EXPR, type1, |
1057 | iv0->step, build_int_cst (type1, 1)); | |
e9eb809d | 1058 | |
7f17528a ZD |
1059 | /* We need to know that iv0->base >= MIN + iv0->step - 1. Since |
1060 | 0 address never belongs to any object, we can assume this for | |
1061 | pointers. */ | |
1062 | if (!POINTER_TYPE_P (type)) | |
e9eb809d | 1063 | { |
5be014d5 | 1064 | bound = fold_build2 (PLUS_EXPR, type1, |
7f17528a ZD |
1065 | TYPE_MIN_VALUE (type), diff); |
1066 | assumption = fold_build2 (GE_EXPR, boolean_type_node, | |
1067 | iv0->base, bound); | |
e9eb809d ZD |
1068 | } |
1069 | ||
7f17528a | 1070 | /* And then we can compute iv0->base - diff, and compare it with |
b8698a0f L |
1071 | iv1->base. */ |
1072 | mbzl = fold_build2 (MINUS_EXPR, type1, | |
d24a32a1 ZD |
1073 | fold_convert (type1, iv0->base), diff); |
1074 | mbzr = fold_convert (type1, iv1->base); | |
e9eb809d | 1075 | } |
7f17528a | 1076 | else |
e9eb809d | 1077 | { |
5be014d5 AP |
1078 | diff = fold_build2 (PLUS_EXPR, type1, |
1079 | iv1->step, build_int_cst (type1, 1)); | |
7f17528a ZD |
1080 | |
1081 | if (!POINTER_TYPE_P (type)) | |
e9eb809d | 1082 | { |
5be014d5 | 1083 | bound = fold_build2 (PLUS_EXPR, type1, |
7f17528a ZD |
1084 | TYPE_MAX_VALUE (type), diff); |
1085 | assumption = fold_build2 (LE_EXPR, boolean_type_node, | |
1086 | iv1->base, bound); | |
e9eb809d ZD |
1087 | } |
1088 | ||
d24a32a1 ZD |
1089 | mbzl = fold_convert (type1, iv0->base); |
1090 | mbzr = fold_build2 (MINUS_EXPR, type1, | |
1091 | fold_convert (type1, iv1->base), diff); | |
7f17528a | 1092 | } |
e9eb809d | 1093 | |
6e682d7e | 1094 | if (!integer_nonzerop (assumption)) |
7f17528a ZD |
1095 | niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, |
1096 | niter->assumptions, assumption); | |
b3ce5b6e ZD |
1097 | if (!rolls_p) |
1098 | { | |
1099 | mbz = fold_build2 (GT_EXPR, boolean_type_node, mbzl, mbzr); | |
1100 | niter->may_be_zero = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, | |
1101 | niter->may_be_zero, mbz); | |
1102 | } | |
7f17528a | 1103 | } |
e9eb809d | 1104 | |
7f17528a ZD |
1105 | /* Determines number of iterations of loop whose ending condition |
1106 | is IV0 < IV1. TYPE is the type of the iv. The number of | |
b3ce5b6e | 1107 | iterations is stored to NITER. BNDS bounds the difference |
e36dc339 ZD |
1108 | IV1->base - IV0->base. EXIT_MUST_BE_TAKEN is true if we know |
1109 | that the exit must be taken eventually. */ | |
7f17528a ZD |
1110 | |
1111 | static bool | |
1112 | number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1, | |
1113 | struct tree_niter_desc *niter, | |
e36dc339 | 1114 | bool exit_must_be_taken, bounds *bnds) |
7f17528a ZD |
1115 | { |
1116 | tree niter_type = unsigned_type_for (type); | |
1117 | tree delta, step, s; | |
b3ce5b6e | 1118 | mpz_t mstep, tmp; |
7f17528a | 1119 | |
6e42ce54 | 1120 | if (integer_nonzerop (iv0->step)) |
17684618 ZD |
1121 | { |
1122 | niter->control = *iv0; | |
1123 | niter->cmp = LT_EXPR; | |
1124 | niter->bound = iv1->base; | |
1125 | } | |
1126 | else | |
1127 | { | |
1128 | niter->control = *iv1; | |
1129 | niter->cmp = GT_EXPR; | |
1130 | niter->bound = iv0->base; | |
1131 | } | |
1132 | ||
7f17528a ZD |
1133 | delta = fold_build2 (MINUS_EXPR, niter_type, |
1134 | fold_convert (niter_type, iv1->base), | |
1135 | fold_convert (niter_type, iv0->base)); | |
1136 | ||
1137 | /* First handle the special case that the step is +-1. */ | |
6e42ce54 ZD |
1138 | if ((integer_onep (iv0->step) && integer_zerop (iv1->step)) |
1139 | || (integer_all_onesp (iv1->step) && integer_zerop (iv0->step))) | |
7f17528a ZD |
1140 | { |
1141 | /* for (i = iv0->base; i < iv1->base; i++) | |
1142 | ||
1143 | or | |
82b85a85 | 1144 | |
7f17528a | 1145 | for (i = iv1->base; i > iv0->base; i--). |
b8698a0f | 1146 | |
7f17528a | 1147 | In both cases # of iterations is iv1->base - iv0->base, assuming that |
b3ce5b6e ZD |
1148 | iv1->base >= iv0->base. |
1149 | ||
1150 | First try to derive a lower bound on the value of | |
1151 | iv1->base - iv0->base, computed in full precision. If the difference | |
1152 | is nonnegative, we are done, otherwise we must record the | |
1153 | condition. */ | |
1154 | ||
1155 | if (mpz_sgn (bnds->below) < 0) | |
1156 | niter->may_be_zero = fold_build2 (LT_EXPR, boolean_type_node, | |
1157 | iv1->base, iv0->base); | |
7f17528a | 1158 | niter->niter = delta; |
807e902e KZ |
1159 | niter->max = widest_int::from (wi::from_mpz (niter_type, bnds->up, false), |
1160 | TYPE_SIGN (niter_type)); | |
7f17528a | 1161 | return true; |
e9eb809d | 1162 | } |
7f17528a | 1163 | |
6e42ce54 | 1164 | if (integer_nonzerop (iv0->step)) |
7f17528a | 1165 | step = fold_convert (niter_type, iv0->step); |
e9eb809d | 1166 | else |
7f17528a ZD |
1167 | step = fold_convert (niter_type, |
1168 | fold_build1 (NEGATE_EXPR, type, iv1->step)); | |
1169 | ||
1170 | /* If we can determine the final value of the control iv exactly, we can | |
1171 | transform the condition to != comparison. In particular, this will be | |
1172 | the case if DELTA is constant. */ | |
b3ce5b6e | 1173 | if (number_of_iterations_lt_to_ne (type, iv0, iv1, niter, &delta, step, |
e36dc339 | 1174 | exit_must_be_taken, bnds)) |
e9eb809d | 1175 | { |
7f17528a ZD |
1176 | affine_iv zps; |
1177 | ||
ff5e9a94 | 1178 | zps.base = build_int_cst (niter_type, 0); |
7f17528a ZD |
1179 | zps.step = step; |
1180 | /* number_of_iterations_lt_to_ne will add assumptions that ensure that | |
1181 | zps does not overflow. */ | |
1182 | zps.no_overflow = true; | |
1183 | ||
b3ce5b6e | 1184 | return number_of_iterations_ne (type, &zps, delta, niter, true, bnds); |
e9eb809d ZD |
1185 | } |
1186 | ||
7f17528a ZD |
1187 | /* Make sure that the control iv does not overflow. */ |
1188 | if (!assert_no_overflow_lt (type, iv0, iv1, niter, step)) | |
1189 | return false; | |
e9eb809d | 1190 | |
7f17528a ZD |
1191 | /* We determine the number of iterations as (delta + step - 1) / step. For |
1192 | this to work, we must know that iv1->base >= iv0->base - step + 1, | |
1193 | otherwise the loop does not roll. */ | |
b3ce5b6e | 1194 | assert_loop_rolls_lt (type, iv0, iv1, niter, bnds); |
7f17528a ZD |
1195 | |
1196 | s = fold_build2 (MINUS_EXPR, niter_type, | |
ff5e9a94 | 1197 | step, build_int_cst (niter_type, 1)); |
7f17528a ZD |
1198 | delta = fold_build2 (PLUS_EXPR, niter_type, delta, s); |
1199 | niter->niter = fold_build2 (FLOOR_DIV_EXPR, niter_type, delta, step); | |
b3ce5b6e ZD |
1200 | |
1201 | mpz_init (mstep); | |
1202 | mpz_init (tmp); | |
807e902e | 1203 | wi::to_mpz (step, mstep, UNSIGNED); |
b3ce5b6e ZD |
1204 | mpz_add (tmp, bnds->up, mstep); |
1205 | mpz_sub_ui (tmp, tmp, 1); | |
1206 | mpz_fdiv_q (tmp, tmp, mstep); | |
807e902e KZ |
1207 | niter->max = widest_int::from (wi::from_mpz (niter_type, tmp, false), |
1208 | TYPE_SIGN (niter_type)); | |
b3ce5b6e ZD |
1209 | mpz_clear (mstep); |
1210 | mpz_clear (tmp); | |
1211 | ||
7f17528a | 1212 | return true; |
e9eb809d ZD |
1213 | } |
1214 | ||
7f17528a ZD |
1215 | /* Determines number of iterations of loop whose ending condition |
1216 | is IV0 <= IV1. TYPE is the type of the iv. The number of | |
e36dc339 | 1217 | iterations is stored to NITER. EXIT_MUST_BE_TAKEN is true if |
f08ac361 | 1218 | we know that this condition must eventually become false (we derived this |
7f17528a | 1219 | earlier, and possibly set NITER->assumptions to make sure this |
b3ce5b6e | 1220 | is the case). BNDS bounds the difference IV1->base - IV0->base. */ |
7f17528a ZD |
1221 | |
1222 | static bool | |
1223 | number_of_iterations_le (tree type, affine_iv *iv0, affine_iv *iv1, | |
e36dc339 | 1224 | struct tree_niter_desc *niter, bool exit_must_be_taken, |
b3ce5b6e | 1225 | bounds *bnds) |
7f17528a ZD |
1226 | { |
1227 | tree assumption; | |
5be014d5 AP |
1228 | tree type1 = type; |
1229 | if (POINTER_TYPE_P (type)) | |
1230 | type1 = sizetype; | |
7f17528a ZD |
1231 | |
1232 | /* Say that IV0 is the control variable. Then IV0 <= IV1 iff | |
1233 | IV0 < IV1 + 1, assuming that IV1 is not equal to the greatest | |
1234 | value of the type. This we must know anyway, since if it is | |
e36dc339 | 1235 | equal to this value, the loop rolls forever. We do not check |
b8698a0f | 1236 | this condition for pointer type ivs, as the code cannot rely on |
e36dc339 ZD |
1237 | the object to that the pointer points being placed at the end of |
1238 | the address space (and more pragmatically, TYPE_{MIN,MAX}_VALUE is | |
1239 | not defined for pointers). */ | |
7f17528a | 1240 | |
e36dc339 | 1241 | if (!exit_must_be_taken && !POINTER_TYPE_P (type)) |
7f17528a | 1242 | { |
6e42ce54 | 1243 | if (integer_nonzerop (iv0->step)) |
7f17528a | 1244 | assumption = fold_build2 (NE_EXPR, boolean_type_node, |
97b4ba9f | 1245 | iv1->base, TYPE_MAX_VALUE (type)); |
7f17528a ZD |
1246 | else |
1247 | assumption = fold_build2 (NE_EXPR, boolean_type_node, | |
97b4ba9f | 1248 | iv0->base, TYPE_MIN_VALUE (type)); |
7f17528a | 1249 | |
6e682d7e | 1250 | if (integer_zerop (assumption)) |
7f17528a | 1251 | return false; |
6e682d7e | 1252 | if (!integer_nonzerop (assumption)) |
7f17528a ZD |
1253 | niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, |
1254 | niter->assumptions, assumption); | |
1255 | } | |
1256 | ||
6e42ce54 | 1257 | if (integer_nonzerop (iv0->step)) |
97b4ba9f JJ |
1258 | { |
1259 | if (POINTER_TYPE_P (type)) | |
5d49b6a7 | 1260 | iv1->base = fold_build_pointer_plus_hwi (iv1->base, 1); |
97b4ba9f JJ |
1261 | else |
1262 | iv1->base = fold_build2 (PLUS_EXPR, type1, iv1->base, | |
1263 | build_int_cst (type1, 1)); | |
1264 | } | |
1265 | else if (POINTER_TYPE_P (type)) | |
5d49b6a7 | 1266 | iv0->base = fold_build_pointer_plus_hwi (iv0->base, -1); |
7f17528a | 1267 | else |
5be014d5 AP |
1268 | iv0->base = fold_build2 (MINUS_EXPR, type1, |
1269 | iv0->base, build_int_cst (type1, 1)); | |
b3ce5b6e | 1270 | |
807e902e | 1271 | bounds_add (bnds, 1, type1); |
b3ce5b6e | 1272 | |
e36dc339 ZD |
1273 | return number_of_iterations_lt (type, iv0, iv1, niter, exit_must_be_taken, |
1274 | bnds); | |
b3ce5b6e ZD |
1275 | } |
1276 | ||
1277 | /* Dumps description of affine induction variable IV to FILE. */ | |
1278 | ||
1279 | static void | |
1280 | dump_affine_iv (FILE *file, affine_iv *iv) | |
1281 | { | |
1282 | if (!integer_zerop (iv->step)) | |
1283 | fprintf (file, "["); | |
1284 | ||
1285 | print_generic_expr (dump_file, iv->base, TDF_SLIM); | |
1286 | ||
1287 | if (!integer_zerop (iv->step)) | |
1288 | { | |
1289 | fprintf (file, ", + , "); | |
1290 | print_generic_expr (dump_file, iv->step, TDF_SLIM); | |
1291 | fprintf (file, "]%s", iv->no_overflow ? "(no_overflow)" : ""); | |
1292 | } | |
7f17528a | 1293 | } |
e9eb809d | 1294 | |
7f17528a ZD |
1295 | /* Determine the number of iterations according to condition (for staying |
1296 | inside loop) which compares two induction variables using comparison | |
1297 | operator CODE. The induction variable on left side of the comparison | |
1298 | is IV0, the right-hand side is IV1. Both induction variables must have | |
1299 | type TYPE, which must be an integer or pointer type. The steps of the | |
1300 | ivs must be constants (or NULL_TREE, which is interpreted as constant zero). | |
f08ac361 | 1301 | |
b3ce5b6e ZD |
1302 | LOOP is the loop whose number of iterations we are determining. |
1303 | ||
f08ac361 ZD |
1304 | ONLY_EXIT is true if we are sure this is the only way the loop could be |
1305 | exited (including possibly non-returning function calls, exceptions, etc.) | |
1306 | -- in this case we can use the information whether the control induction | |
1307 | variables can overflow or not in a more efficient way. | |
b8698a0f | 1308 | |
870ca331 JH |
1309 | if EVERY_ITERATION is true, we know the test is executed on every iteration. |
1310 | ||
7f17528a | 1311 | The results (number of iterations and assumptions as described in |
3fadf78a | 1312 | comments at struct tree_niter_desc in tree-ssa-loop.h) are stored to NITER. |
7f17528a ZD |
1313 | Returns false if it fails to determine number of iterations, true if it |
1314 | was determined (possibly with some assumptions). */ | |
c33e657d ZD |
1315 | |
1316 | static bool | |
b3ce5b6e ZD |
1317 | number_of_iterations_cond (struct loop *loop, |
1318 | tree type, affine_iv *iv0, enum tree_code code, | |
f08ac361 | 1319 | affine_iv *iv1, struct tree_niter_desc *niter, |
870ca331 | 1320 | bool only_exit, bool every_iteration) |
e9eb809d | 1321 | { |
e36dc339 | 1322 | bool exit_must_be_taken = false, ret; |
b3ce5b6e | 1323 | bounds bnds; |
7f17528a | 1324 | |
870ca331 JH |
1325 | /* If the test is not executed every iteration, wrapping may make the test |
1326 | to pass again. | |
1327 | TODO: the overflow case can be still used as unreliable estimate of upper | |
1328 | bound. But we have no API to pass it down to number of iterations code | |
1329 | and, at present, it will not use it anyway. */ | |
1330 | if (!every_iteration | |
1331 | && (!iv0->no_overflow || !iv1->no_overflow | |
1332 | || code == NE_EXPR || code == EQ_EXPR)) | |
1333 | return false; | |
1334 | ||
7f17528a ZD |
1335 | /* The meaning of these assumptions is this: |
1336 | if !assumptions | |
1337 | then the rest of information does not have to be valid | |
1338 | if may_be_zero then the loop does not roll, even if | |
1339 | niter != 0. */ | |
1340 | niter->assumptions = boolean_true_node; | |
1341 | niter->may_be_zero = boolean_false_node; | |
1342 | niter->niter = NULL_TREE; | |
807e902e | 1343 | niter->max = 0; |
17684618 ZD |
1344 | niter->bound = NULL_TREE; |
1345 | niter->cmp = ERROR_MARK; | |
1346 | ||
7f17528a ZD |
1347 | /* Make < comparison from > ones, and for NE_EXPR comparisons, ensure that |
1348 | the control variable is on lhs. */ | |
1349 | if (code == GE_EXPR || code == GT_EXPR | |
6e42ce54 | 1350 | || (code == NE_EXPR && integer_zerop (iv0->step))) |
c33e657d | 1351 | { |
a6f778b2 | 1352 | SWAP (iv0, iv1); |
c33e657d ZD |
1353 | code = swap_tree_comparison (code); |
1354 | } | |
e9eb809d | 1355 | |
7f17528a | 1356 | if (POINTER_TYPE_P (type)) |
e9eb809d | 1357 | { |
7f17528a ZD |
1358 | /* Comparison of pointers is undefined unless both iv0 and iv1 point |
1359 | to the same object. If they do, the control variable cannot wrap | |
1360 | (as wrap around the bounds of memory will never return a pointer | |
1361 | that would be guaranteed to point to the same object, even if we | |
e36dc339 | 1362 | avoid undefined behavior by casting to size_t and back). */ |
7f17528a ZD |
1363 | iv0->no_overflow = true; |
1364 | iv1->no_overflow = true; | |
1365 | } | |
e9eb809d | 1366 | |
e36dc339 ZD |
1367 | /* If the control induction variable does not overflow and the only exit |
1368 | from the loop is the one that we analyze, we know it must be taken | |
1369 | eventually. */ | |
1370 | if (only_exit) | |
1371 | { | |
1372 | if (!integer_zerop (iv0->step) && iv0->no_overflow) | |
1373 | exit_must_be_taken = true; | |
1374 | else if (!integer_zerop (iv1->step) && iv1->no_overflow) | |
1375 | exit_must_be_taken = true; | |
1376 | } | |
e9eb809d | 1377 | |
7f17528a ZD |
1378 | /* We can handle the case when neither of the sides of the comparison is |
1379 | invariant, provided that the test is NE_EXPR. This rarely occurs in | |
1380 | practice, but it is simple enough to manage. */ | |
6e42ce54 | 1381 | if (!integer_zerop (iv0->step) && !integer_zerop (iv1->step)) |
7f17528a | 1382 | { |
5ece9847 | 1383 | tree step_type = POINTER_TYPE_P (type) ? sizetype : type; |
7f17528a ZD |
1384 | if (code != NE_EXPR) |
1385 | return false; | |
e9eb809d | 1386 | |
5ece9847 | 1387 | iv0->step = fold_binary_to_constant (MINUS_EXPR, step_type, |
7f17528a ZD |
1388 | iv0->step, iv1->step); |
1389 | iv0->no_overflow = false; | |
5ece9847 | 1390 | iv1->step = build_int_cst (step_type, 0); |
7f17528a ZD |
1391 | iv1->no_overflow = true; |
1392 | } | |
c33e657d | 1393 | |
7f17528a ZD |
1394 | /* If the result of the comparison is a constant, the loop is weird. More |
1395 | precise handling would be possible, but the situation is not common enough | |
1396 | to waste time on it. */ | |
6e42ce54 | 1397 | if (integer_zerop (iv0->step) && integer_zerop (iv1->step)) |
7f17528a | 1398 | return false; |
c33e657d | 1399 | |
7f17528a ZD |
1400 | /* Ignore loops of while (i-- < 10) type. */ |
1401 | if (code != NE_EXPR) | |
1402 | { | |
1403 | if (iv0->step && tree_int_cst_sign_bit (iv0->step)) | |
c33e657d | 1404 | return false; |
c33e657d | 1405 | |
6e42ce54 | 1406 | if (!integer_zerop (iv1->step) && !tree_int_cst_sign_bit (iv1->step)) |
c33e657d | 1407 | return false; |
7f17528a | 1408 | } |
e9eb809d | 1409 | |
c0220ea4 | 1410 | /* If the loop exits immediately, there is nothing to do. */ |
5a892248 RB |
1411 | tree tem = fold_binary (code, boolean_type_node, iv0->base, iv1->base); |
1412 | if (tem && integer_zerop (tem)) | |
7f17528a | 1413 | { |
ff5e9a94 | 1414 | niter->niter = build_int_cst (unsigned_type_for (type), 0); |
807e902e | 1415 | niter->max = 0; |
7f17528a ZD |
1416 | return true; |
1417 | } | |
b8698a0f | 1418 | |
7f17528a ZD |
1419 | /* OK, now we know we have a senseful loop. Handle several cases, depending |
1420 | on what comparison operator is used. */ | |
b3ce5b6e ZD |
1421 | bound_difference (loop, iv1->base, iv0->base, &bnds); |
1422 | ||
1423 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1424 | { | |
1425 | fprintf (dump_file, | |
4dad0aca | 1426 | "Analyzing # of iterations of loop %d\n", loop->num); |
b3ce5b6e ZD |
1427 | |
1428 | fprintf (dump_file, " exit condition "); | |
1429 | dump_affine_iv (dump_file, iv0); | |
1430 | fprintf (dump_file, " %s ", | |
1431 | code == NE_EXPR ? "!=" | |
1432 | : code == LT_EXPR ? "<" | |
1433 | : "<="); | |
1434 | dump_affine_iv (dump_file, iv1); | |
1435 | fprintf (dump_file, "\n"); | |
1436 | ||
1437 | fprintf (dump_file, " bounds on difference of bases: "); | |
1438 | mpz_out_str (dump_file, 10, bnds.below); | |
1439 | fprintf (dump_file, " ... "); | |
1440 | mpz_out_str (dump_file, 10, bnds.up); | |
1441 | fprintf (dump_file, "\n"); | |
1442 | } | |
1443 | ||
7f17528a ZD |
1444 | switch (code) |
1445 | { | |
1446 | case NE_EXPR: | |
6e42ce54 | 1447 | gcc_assert (integer_zerop (iv1->step)); |
b3ce5b6e | 1448 | ret = number_of_iterations_ne (type, iv0, iv1->base, niter, |
e36dc339 | 1449 | exit_must_be_taken, &bnds); |
b3ce5b6e ZD |
1450 | break; |
1451 | ||
7f17528a | 1452 | case LT_EXPR: |
e36dc339 | 1453 | ret = number_of_iterations_lt (type, iv0, iv1, niter, exit_must_be_taken, |
b3ce5b6e ZD |
1454 | &bnds); |
1455 | break; | |
1456 | ||
7f17528a | 1457 | case LE_EXPR: |
e36dc339 | 1458 | ret = number_of_iterations_le (type, iv0, iv1, niter, exit_must_be_taken, |
b3ce5b6e ZD |
1459 | &bnds); |
1460 | break; | |
1461 | ||
c33e657d ZD |
1462 | default: |
1463 | gcc_unreachable (); | |
1464 | } | |
b3ce5b6e ZD |
1465 | |
1466 | mpz_clear (bnds.up); | |
1467 | mpz_clear (bnds.below); | |
1468 | ||
1469 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1470 | { | |
1471 | if (ret) | |
1472 | { | |
1473 | fprintf (dump_file, " result:\n"); | |
1474 | if (!integer_nonzerop (niter->assumptions)) | |
1475 | { | |
1476 | fprintf (dump_file, " under assumptions "); | |
1477 | print_generic_expr (dump_file, niter->assumptions, TDF_SLIM); | |
1478 | fprintf (dump_file, "\n"); | |
1479 | } | |
1480 | ||
1481 | if (!integer_zerop (niter->may_be_zero)) | |
1482 | { | |
1483 | fprintf (dump_file, " zero if "); | |
1484 | print_generic_expr (dump_file, niter->may_be_zero, TDF_SLIM); | |
1485 | fprintf (dump_file, "\n"); | |
1486 | } | |
1487 | ||
1488 | fprintf (dump_file, " # of iterations "); | |
1489 | print_generic_expr (dump_file, niter->niter, TDF_SLIM); | |
1490 | fprintf (dump_file, ", bounded by "); | |
807e902e | 1491 | print_decu (niter->max, dump_file); |
b3ce5b6e ZD |
1492 | fprintf (dump_file, "\n"); |
1493 | } | |
1494 | else | |
1495 | fprintf (dump_file, " failed\n\n"); | |
1496 | } | |
1497 | return ret; | |
e9eb809d ZD |
1498 | } |
1499 | ||
1d481ba8 ZD |
1500 | /* Substitute NEW for OLD in EXPR and fold the result. */ |
1501 | ||
1502 | static tree | |
c22940cd | 1503 | simplify_replace_tree (tree expr, tree old, tree new_tree) |
1d481ba8 ZD |
1504 | { |
1505 | unsigned i, n; | |
1506 | tree ret = NULL_TREE, e, se; | |
1507 | ||
1508 | if (!expr) | |
1509 | return NULL_TREE; | |
1510 | ||
76c85743 RG |
1511 | /* Do not bother to replace constants. */ |
1512 | if (CONSTANT_CLASS_P (old)) | |
1513 | return expr; | |
1514 | ||
1d481ba8 ZD |
1515 | if (expr == old |
1516 | || operand_equal_p (expr, old, 0)) | |
c22940cd | 1517 | return unshare_expr (new_tree); |
1d481ba8 | 1518 | |
726a989a | 1519 | if (!EXPR_P (expr)) |
1d481ba8 ZD |
1520 | return expr; |
1521 | ||
5039610b | 1522 | n = TREE_OPERAND_LENGTH (expr); |
1d481ba8 ZD |
1523 | for (i = 0; i < n; i++) |
1524 | { | |
1525 | e = TREE_OPERAND (expr, i); | |
c22940cd | 1526 | se = simplify_replace_tree (e, old, new_tree); |
1d481ba8 ZD |
1527 | if (e == se) |
1528 | continue; | |
1529 | ||
1530 | if (!ret) | |
1531 | ret = copy_node (expr); | |
1532 | ||
1533 | TREE_OPERAND (ret, i) = se; | |
1534 | } | |
1535 | ||
1536 | return (ret ? fold (ret) : expr); | |
1537 | } | |
1538 | ||
be1b5cba ZD |
1539 | /* Expand definitions of ssa names in EXPR as long as they are simple |
1540 | enough, and return the new expression. */ | |
1541 | ||
d7bf3bcf | 1542 | tree |
be1b5cba ZD |
1543 | expand_simple_operations (tree expr) |
1544 | { | |
1545 | unsigned i, n; | |
726a989a | 1546 | tree ret = NULL_TREE, e, ee, e1; |
6fff2603 | 1547 | enum tree_code code; |
726a989a | 1548 | gimple stmt; |
6fff2603 JJ |
1549 | |
1550 | if (expr == NULL_TREE) | |
1551 | return expr; | |
be1b5cba ZD |
1552 | |
1553 | if (is_gimple_min_invariant (expr)) | |
1554 | return expr; | |
1555 | ||
6fff2603 | 1556 | code = TREE_CODE (expr); |
be1b5cba ZD |
1557 | if (IS_EXPR_CODE_CLASS (TREE_CODE_CLASS (code))) |
1558 | { | |
5039610b | 1559 | n = TREE_OPERAND_LENGTH (expr); |
be1b5cba ZD |
1560 | for (i = 0; i < n; i++) |
1561 | { | |
1562 | e = TREE_OPERAND (expr, i); | |
1563 | ee = expand_simple_operations (e); | |
1564 | if (e == ee) | |
1565 | continue; | |
1566 | ||
1567 | if (!ret) | |
1568 | ret = copy_node (expr); | |
1569 | ||
1570 | TREE_OPERAND (ret, i) = ee; | |
1571 | } | |
1572 | ||
6ac01510 ILT |
1573 | if (!ret) |
1574 | return expr; | |
1575 | ||
1576 | fold_defer_overflow_warnings (); | |
1577 | ret = fold (ret); | |
1578 | fold_undefer_and_ignore_overflow_warnings (); | |
1579 | return ret; | |
be1b5cba ZD |
1580 | } |
1581 | ||
1582 | if (TREE_CODE (expr) != SSA_NAME) | |
1583 | return expr; | |
1584 | ||
1585 | stmt = SSA_NAME_DEF_STMT (expr); | |
726a989a | 1586 | if (gimple_code (stmt) == GIMPLE_PHI) |
b3ce5b6e ZD |
1587 | { |
1588 | basic_block src, dest; | |
1589 | ||
726a989a | 1590 | if (gimple_phi_num_args (stmt) != 1) |
b3ce5b6e ZD |
1591 | return expr; |
1592 | e = PHI_ARG_DEF (stmt, 0); | |
1593 | ||
1594 | /* Avoid propagating through loop exit phi nodes, which | |
1595 | could break loop-closed SSA form restrictions. */ | |
726a989a | 1596 | dest = gimple_bb (stmt); |
b3ce5b6e ZD |
1597 | src = single_pred (dest); |
1598 | if (TREE_CODE (e) == SSA_NAME | |
1599 | && src->loop_father != dest->loop_father) | |
1600 | return expr; | |
1601 | ||
1602 | return expand_simple_operations (e); | |
1603 | } | |
726a989a | 1604 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
be1b5cba ZD |
1605 | return expr; |
1606 | ||
c3a9b91b RB |
1607 | /* Avoid expanding to expressions that contain SSA names that need |
1608 | to take part in abnormal coalescing. */ | |
1609 | ssa_op_iter iter; | |
1610 | FOR_EACH_SSA_TREE_OPERAND (e, stmt, iter, SSA_OP_USE) | |
1611 | if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (e)) | |
1612 | return expr; | |
1613 | ||
726a989a RB |
1614 | e = gimple_assign_rhs1 (stmt); |
1615 | code = gimple_assign_rhs_code (stmt); | |
1616 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) | |
1617 | { | |
1618 | if (is_gimple_min_invariant (e)) | |
1619 | return e; | |
1620 | ||
1621 | if (code == SSA_NAME) | |
1622 | return expand_simple_operations (e); | |
1623 | ||
1624 | return expr; | |
1625 | } | |
1626 | ||
1627 | switch (code) | |
1628 | { | |
1a87cf0c | 1629 | CASE_CONVERT: |
726a989a RB |
1630 | /* Casts are simple. */ |
1631 | ee = expand_simple_operations (e); | |
1632 | return fold_build1 (code, TREE_TYPE (expr), ee); | |
1633 | ||
1634 | case PLUS_EXPR: | |
1635 | case MINUS_EXPR: | |
1636 | case POINTER_PLUS_EXPR: | |
be1b5cba | 1637 | /* And increments and decrements by a constant are simple. */ |
726a989a RB |
1638 | e1 = gimple_assign_rhs2 (stmt); |
1639 | if (!is_gimple_min_invariant (e1)) | |
1640 | return expr; | |
1641 | ||
1642 | ee = expand_simple_operations (e); | |
1643 | return fold_build2 (code, TREE_TYPE (expr), ee, e1); | |
be1b5cba | 1644 | |
726a989a RB |
1645 | default: |
1646 | return expr; | |
1647 | } | |
be1b5cba ZD |
1648 | } |
1649 | ||
e9eb809d | 1650 | /* Tries to simplify EXPR using the condition COND. Returns the simplified |
be1b5cba | 1651 | expression (or EXPR unchanged, if no simplification was possible). */ |
e9eb809d ZD |
1652 | |
1653 | static tree | |
be1b5cba | 1654 | tree_simplify_using_condition_1 (tree cond, tree expr) |
e9eb809d ZD |
1655 | { |
1656 | bool changed; | |
be1b5cba | 1657 | tree e, te, e0, e1, e2, notcond; |
e9eb809d ZD |
1658 | enum tree_code code = TREE_CODE (expr); |
1659 | ||
1660 | if (code == INTEGER_CST) | |
1661 | return expr; | |
1662 | ||
1663 | if (code == TRUTH_OR_EXPR | |
1664 | || code == TRUTH_AND_EXPR | |
1665 | || code == COND_EXPR) | |
1666 | { | |
1667 | changed = false; | |
1668 | ||
be1b5cba | 1669 | e0 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 0)); |
e9eb809d ZD |
1670 | if (TREE_OPERAND (expr, 0) != e0) |
1671 | changed = true; | |
1672 | ||
be1b5cba | 1673 | e1 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 1)); |
e9eb809d ZD |
1674 | if (TREE_OPERAND (expr, 1) != e1) |
1675 | changed = true; | |
1676 | ||
1677 | if (code == COND_EXPR) | |
1678 | { | |
be1b5cba | 1679 | e2 = tree_simplify_using_condition_1 (cond, TREE_OPERAND (expr, 2)); |
e9eb809d ZD |
1680 | if (TREE_OPERAND (expr, 2) != e2) |
1681 | changed = true; | |
1682 | } | |
1683 | else | |
1684 | e2 = NULL_TREE; | |
1685 | ||
1686 | if (changed) | |
1687 | { | |
1688 | if (code == COND_EXPR) | |
c33e657d | 1689 | expr = fold_build3 (code, boolean_type_node, e0, e1, e2); |
e9eb809d | 1690 | else |
c33e657d | 1691 | expr = fold_build2 (code, boolean_type_node, e0, e1); |
e9eb809d ZD |
1692 | } |
1693 | ||
1694 | return expr; | |
1695 | } | |
1696 | ||
1d481ba8 ZD |
1697 | /* In case COND is equality, we may be able to simplify EXPR by copy/constant |
1698 | propagation, and vice versa. Fold does not handle this, since it is | |
1699 | considered too expensive. */ | |
1700 | if (TREE_CODE (cond) == EQ_EXPR) | |
1701 | { | |
1702 | e0 = TREE_OPERAND (cond, 0); | |
1703 | e1 = TREE_OPERAND (cond, 1); | |
1704 | ||
1705 | /* We know that e0 == e1. Check whether we cannot simplify expr | |
1706 | using this fact. */ | |
1707 | e = simplify_replace_tree (expr, e0, e1); | |
6e682d7e | 1708 | if (integer_zerop (e) || integer_nonzerop (e)) |
1d481ba8 ZD |
1709 | return e; |
1710 | ||
1711 | e = simplify_replace_tree (expr, e1, e0); | |
6e682d7e | 1712 | if (integer_zerop (e) || integer_nonzerop (e)) |
1d481ba8 ZD |
1713 | return e; |
1714 | } | |
1715 | if (TREE_CODE (expr) == EQ_EXPR) | |
1716 | { | |
1717 | e0 = TREE_OPERAND (expr, 0); | |
1718 | e1 = TREE_OPERAND (expr, 1); | |
1719 | ||
1720 | /* If e0 == e1 (EXPR) implies !COND, then EXPR cannot be true. */ | |
1721 | e = simplify_replace_tree (cond, e0, e1); | |
6e682d7e | 1722 | if (integer_zerop (e)) |
1d481ba8 ZD |
1723 | return e; |
1724 | e = simplify_replace_tree (cond, e1, e0); | |
6e682d7e | 1725 | if (integer_zerop (e)) |
1d481ba8 ZD |
1726 | return e; |
1727 | } | |
1728 | if (TREE_CODE (expr) == NE_EXPR) | |
1729 | { | |
1730 | e0 = TREE_OPERAND (expr, 0); | |
1731 | e1 = TREE_OPERAND (expr, 1); | |
1732 | ||
1733 | /* If e0 == e1 (!EXPR) implies !COND, then EXPR must be true. */ | |
1734 | e = simplify_replace_tree (cond, e0, e1); | |
6e682d7e | 1735 | if (integer_zerop (e)) |
1d481ba8 ZD |
1736 | return boolean_true_node; |
1737 | e = simplify_replace_tree (cond, e1, e0); | |
6e682d7e | 1738 | if (integer_zerop (e)) |
1d481ba8 ZD |
1739 | return boolean_true_node; |
1740 | } | |
1741 | ||
be1b5cba ZD |
1742 | te = expand_simple_operations (expr); |
1743 | ||
e9eb809d ZD |
1744 | /* Check whether COND ==> EXPR. */ |
1745 | notcond = invert_truthvalue (cond); | |
2f133f46 | 1746 | e = fold_binary (TRUTH_OR_EXPR, boolean_type_node, notcond, te); |
6e682d7e | 1747 | if (e && integer_nonzerop (e)) |
e9eb809d ZD |
1748 | return e; |
1749 | ||
1750 | /* Check whether COND ==> not EXPR. */ | |
2f133f46 | 1751 | e = fold_binary (TRUTH_AND_EXPR, boolean_type_node, cond, te); |
6e682d7e | 1752 | if (e && integer_zerop (e)) |
e9eb809d ZD |
1753 | return e; |
1754 | ||
1755 | return expr; | |
1756 | } | |
1757 | ||
be1b5cba ZD |
1758 | /* Tries to simplify EXPR using the condition COND. Returns the simplified |
1759 | expression (or EXPR unchanged, if no simplification was possible). | |
1760 | Wrapper around tree_simplify_using_condition_1 that ensures that chains | |
1761 | of simple operations in definitions of ssa names in COND are expanded, | |
1762 | so that things like casts or incrementing the value of the bound before | |
1763 | the loop do not cause us to fail. */ | |
1764 | ||
1765 | static tree | |
1766 | tree_simplify_using_condition (tree cond, tree expr) | |
1767 | { | |
1768 | cond = expand_simple_operations (cond); | |
1769 | ||
1770 | return tree_simplify_using_condition_1 (cond, expr); | |
1771 | } | |
b16fb82d | 1772 | |
e9eb809d | 1773 | /* Tries to simplify EXPR using the conditions on entry to LOOP. |
e9eb809d ZD |
1774 | Returns the simplified expression (or EXPR unchanged, if no |
1775 | simplification was possible).*/ | |
1776 | ||
1777 | static tree | |
b3ce5b6e | 1778 | simplify_using_initial_conditions (struct loop *loop, tree expr) |
e9eb809d ZD |
1779 | { |
1780 | edge e; | |
1781 | basic_block bb; | |
726a989a | 1782 | gimple stmt; |
b3ce5b6e | 1783 | tree cond; |
b16fb82d | 1784 | int cnt = 0; |
e9eb809d ZD |
1785 | |
1786 | if (TREE_CODE (expr) == INTEGER_CST) | |
1787 | return expr; | |
1788 | ||
b16fb82d RG |
1789 | /* Limit walking the dominators to avoid quadraticness in |
1790 | the number of BBs times the number of loops in degenerate | |
1791 | cases. */ | |
e9eb809d | 1792 | for (bb = loop->header; |
fefa31b5 | 1793 | bb != ENTRY_BLOCK_PTR_FOR_FN (cfun) && cnt < MAX_DOMINATORS_TO_WALK; |
e9eb809d ZD |
1794 | bb = get_immediate_dominator (CDI_DOMINATORS, bb)) |
1795 | { | |
c5cbcccf | 1796 | if (!single_pred_p (bb)) |
e9eb809d | 1797 | continue; |
c5cbcccf | 1798 | e = single_pred_edge (bb); |
e9eb809d ZD |
1799 | |
1800 | if (!(e->flags & (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE))) | |
1801 | continue; | |
1802 | ||
726a989a RB |
1803 | stmt = last_stmt (e->src); |
1804 | cond = fold_build2 (gimple_cond_code (stmt), | |
1805 | boolean_type_node, | |
1806 | gimple_cond_lhs (stmt), | |
1807 | gimple_cond_rhs (stmt)); | |
e9eb809d ZD |
1808 | if (e->flags & EDGE_FALSE_VALUE) |
1809 | cond = invert_truthvalue (cond); | |
b3ce5b6e | 1810 | expr = tree_simplify_using_condition (cond, expr); |
b16fb82d | 1811 | ++cnt; |
e9eb809d ZD |
1812 | } |
1813 | ||
1814 | return expr; | |
1815 | } | |
1816 | ||
c33e657d ZD |
1817 | /* Tries to simplify EXPR using the evolutions of the loop invariants |
1818 | in the superloops of LOOP. Returns the simplified expression | |
1819 | (or EXPR unchanged, if no simplification was possible). */ | |
1820 | ||
1821 | static tree | |
1822 | simplify_using_outer_evolutions (struct loop *loop, tree expr) | |
1823 | { | |
1824 | enum tree_code code = TREE_CODE (expr); | |
1825 | bool changed; | |
1826 | tree e, e0, e1, e2; | |
1827 | ||
1828 | if (is_gimple_min_invariant (expr)) | |
1829 | return expr; | |
1830 | ||
1831 | if (code == TRUTH_OR_EXPR | |
1832 | || code == TRUTH_AND_EXPR | |
1833 | || code == COND_EXPR) | |
1834 | { | |
1835 | changed = false; | |
1836 | ||
1837 | e0 = simplify_using_outer_evolutions (loop, TREE_OPERAND (expr, 0)); | |
1838 | if (TREE_OPERAND (expr, 0) != e0) | |
1839 | changed = true; | |
1840 | ||
1841 | e1 = simplify_using_outer_evolutions (loop, TREE_OPERAND (expr, 1)); | |
1842 | if (TREE_OPERAND (expr, 1) != e1) | |
1843 | changed = true; | |
1844 | ||
1845 | if (code == COND_EXPR) | |
1846 | { | |
1847 | e2 = simplify_using_outer_evolutions (loop, TREE_OPERAND (expr, 2)); | |
1848 | if (TREE_OPERAND (expr, 2) != e2) | |
1849 | changed = true; | |
1850 | } | |
1851 | else | |
1852 | e2 = NULL_TREE; | |
1853 | ||
1854 | if (changed) | |
1855 | { | |
1856 | if (code == COND_EXPR) | |
1857 | expr = fold_build3 (code, boolean_type_node, e0, e1, e2); | |
1858 | else | |
1859 | expr = fold_build2 (code, boolean_type_node, e0, e1); | |
1860 | } | |
1861 | ||
1862 | return expr; | |
1863 | } | |
1864 | ||
1865 | e = instantiate_parameters (loop, expr); | |
1866 | if (is_gimple_min_invariant (e)) | |
1867 | return e; | |
1868 | ||
1869 | return expr; | |
1870 | } | |
1871 | ||
f08ac361 ZD |
1872 | /* Returns true if EXIT is the only possible exit from LOOP. */ |
1873 | ||
52778e2a | 1874 | bool |
22ea9ec0 | 1875 | loop_only_exit_p (const struct loop *loop, const_edge exit) |
f08ac361 ZD |
1876 | { |
1877 | basic_block *body; | |
726a989a | 1878 | gimple_stmt_iterator bsi; |
f08ac361 | 1879 | unsigned i; |
726a989a | 1880 | gimple call; |
f08ac361 | 1881 | |
ac8f6c69 | 1882 | if (exit != single_exit (loop)) |
f08ac361 ZD |
1883 | return false; |
1884 | ||
1885 | body = get_loop_body (loop); | |
1886 | for (i = 0; i < loop->num_nodes; i++) | |
1887 | { | |
726a989a | 1888 | for (bsi = gsi_start_bb (body[i]); !gsi_end_p (bsi); gsi_next (&bsi)) |
f08ac361 | 1889 | { |
726a989a RB |
1890 | call = gsi_stmt (bsi); |
1891 | if (gimple_code (call) != GIMPLE_CALL) | |
1892 | continue; | |
1893 | ||
1894 | if (gimple_has_side_effects (call)) | |
f08ac361 ZD |
1895 | { |
1896 | free (body); | |
1897 | return false; | |
1898 | } | |
1899 | } | |
1900 | } | |
1901 | ||
1902 | free (body); | |
1903 | return true; | |
1904 | } | |
1905 | ||
e9eb809d ZD |
1906 | /* Stores description of number of iterations of LOOP derived from |
1907 | EXIT (an exit edge of the LOOP) in NITER. Returns true if some | |
1908 | useful information could be derived (and fields of NITER has | |
1909 | meaning described in comments at struct tree_niter_desc | |
f9cc1a70 PB |
1910 | declaration), false otherwise. If WARN is true and |
1911 | -Wunsafe-loop-optimizations was given, warn if the optimizer is going to use | |
cd0f6278 JH |
1912 | potentially unsafe assumptions. |
1913 | When EVERY_ITERATION is true, only tests that are known to be executed | |
1914 | every iteration are considered (i.e. only test that alone bounds the loop). | |
1915 | */ | |
e9eb809d ZD |
1916 | |
1917 | bool | |
1918 | number_of_iterations_exit (struct loop *loop, edge exit, | |
f9cc1a70 | 1919 | struct tree_niter_desc *niter, |
cd0f6278 | 1920 | bool warn, bool every_iteration) |
e9eb809d | 1921 | { |
726a989a RB |
1922 | gimple stmt; |
1923 | tree type; | |
a6f778b2 | 1924 | tree op0, op1; |
e9eb809d | 1925 | enum tree_code code; |
a6f778b2 | 1926 | affine_iv iv0, iv1; |
870ca331 | 1927 | bool safe; |
e9eb809d | 1928 | |
870ca331 JH |
1929 | safe = dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src); |
1930 | ||
1931 | if (every_iteration && !safe) | |
e9eb809d ZD |
1932 | return false; |
1933 | ||
1934 | niter->assumptions = boolean_false_node; | |
1935 | stmt = last_stmt (exit->src); | |
726a989a | 1936 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) |
e9eb809d ZD |
1937 | return false; |
1938 | ||
1939 | /* We want the condition for staying inside loop. */ | |
726a989a | 1940 | code = gimple_cond_code (stmt); |
e9eb809d | 1941 | if (exit->flags & EDGE_TRUE_VALUE) |
726a989a | 1942 | code = invert_tree_comparison (code, false); |
e9eb809d | 1943 | |
e9eb809d ZD |
1944 | switch (code) |
1945 | { | |
1946 | case GT_EXPR: | |
1947 | case GE_EXPR: | |
e9eb809d ZD |
1948 | case LT_EXPR: |
1949 | case LE_EXPR: | |
870ca331 | 1950 | case NE_EXPR: |
e9eb809d ZD |
1951 | break; |
1952 | ||
1953 | default: | |
1954 | return false; | |
1955 | } | |
b8698a0f | 1956 | |
726a989a RB |
1957 | op0 = gimple_cond_lhs (stmt); |
1958 | op1 = gimple_cond_rhs (stmt); | |
e9eb809d ZD |
1959 | type = TREE_TYPE (op0); |
1960 | ||
1961 | if (TREE_CODE (type) != INTEGER_TYPE | |
b3393f1f | 1962 | && !POINTER_TYPE_P (type)) |
e9eb809d | 1963 | return false; |
b8698a0f | 1964 | |
f017bf5e | 1965 | if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, false)) |
e9eb809d | 1966 | return false; |
f017bf5e | 1967 | if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, false)) |
e9eb809d ZD |
1968 | return false; |
1969 | ||
6ac01510 | 1970 | /* We don't want to see undefined signed overflow warnings while |
ea2c620c | 1971 | computing the number of iterations. */ |
6ac01510 ILT |
1972 | fold_defer_overflow_warnings (); |
1973 | ||
7f17528a ZD |
1974 | iv0.base = expand_simple_operations (iv0.base); |
1975 | iv1.base = expand_simple_operations (iv1.base); | |
b3ce5b6e | 1976 | if (!number_of_iterations_cond (loop, type, &iv0, code, &iv1, niter, |
870ca331 | 1977 | loop_only_exit_p (loop, exit), safe)) |
6ac01510 ILT |
1978 | { |
1979 | fold_undefer_and_ignore_overflow_warnings (); | |
1980 | return false; | |
1981 | } | |
c33e657d ZD |
1982 | |
1983 | if (optimize >= 3) | |
1984 | { | |
1985 | niter->assumptions = simplify_using_outer_evolutions (loop, | |
1986 | niter->assumptions); | |
1987 | niter->may_be_zero = simplify_using_outer_evolutions (loop, | |
1988 | niter->may_be_zero); | |
1989 | niter->niter = simplify_using_outer_evolutions (loop, niter->niter); | |
1990 | } | |
e9eb809d | 1991 | |
e9eb809d ZD |
1992 | niter->assumptions |
1993 | = simplify_using_initial_conditions (loop, | |
b3ce5b6e | 1994 | niter->assumptions); |
e9eb809d ZD |
1995 | niter->may_be_zero |
1996 | = simplify_using_initial_conditions (loop, | |
b3ce5b6e | 1997 | niter->may_be_zero); |
f9cc1a70 | 1998 | |
6ac01510 ILT |
1999 | fold_undefer_and_ignore_overflow_warnings (); |
2000 | ||
f2a1b469 JH |
2001 | /* If NITER has simplified into a constant, update MAX. */ |
2002 | if (TREE_CODE (niter->niter) == INTEGER_CST) | |
807e902e | 2003 | niter->max = wi::to_widest (niter->niter); |
f2a1b469 | 2004 | |
f9cc1a70 PB |
2005 | if (integer_onep (niter->assumptions)) |
2006 | return true; | |
2007 | ||
2008 | /* With -funsafe-loop-optimizations we assume that nothing bad can happen. | |
2009 | But if we can prove that there is overflow or some other source of weird | |
2010 | behavior, ignore the loop even with -funsafe-loop-optimizations. */ | |
1551d44a | 2011 | if (integer_zerop (niter->assumptions) || !single_exit (loop)) |
f9cc1a70 PB |
2012 | return false; |
2013 | ||
2014 | if (flag_unsafe_loop_optimizations) | |
2015 | niter->assumptions = boolean_true_node; | |
2016 | ||
2017 | if (warn) | |
2018 | { | |
2019 | const char *wording; | |
726a989a | 2020 | location_t loc = gimple_location (stmt); |
b8698a0f | 2021 | |
f9cc1a70 PB |
2022 | /* We can provide a more specific warning if one of the operator is |
2023 | constant and the other advances by +1 or -1. */ | |
6e42ce54 ZD |
2024 | if (!integer_zerop (iv1.step) |
2025 | ? (integer_zerop (iv0.step) | |
a6f778b2 | 2026 | && (integer_onep (iv1.step) || integer_all_onesp (iv1.step))) |
6e42ce54 | 2027 | : (integer_onep (iv0.step) || integer_all_onesp (iv0.step))) |
f9cc1a70 PB |
2028 | wording = |
2029 | flag_unsafe_loop_optimizations | |
2030 | ? N_("assuming that the loop is not infinite") | |
2031 | : N_("cannot optimize possibly infinite loops"); | |
2032 | else | |
b8698a0f | 2033 | wording = |
f9cc1a70 PB |
2034 | flag_unsafe_loop_optimizations |
2035 | ? N_("assuming that the loop counter does not overflow") | |
2036 | : N_("cannot optimize loop, the loop counter may overflow"); | |
2037 | ||
fab922b1 MLI |
2038 | warning_at ((LOCATION_LINE (loc) > 0) ? loc : input_location, |
2039 | OPT_Wunsafe_loop_optimizations, "%s", gettext (wording)); | |
f9cc1a70 PB |
2040 | } |
2041 | ||
2042 | return flag_unsafe_loop_optimizations; | |
e9eb809d ZD |
2043 | } |
2044 | ||
ca4c3169 ZD |
2045 | /* Try to determine the number of iterations of LOOP. If we succeed, |
2046 | expression giving number of iterations is returned and *EXIT is | |
2047 | set to the edge from that the information is obtained. Otherwise | |
2048 | chrec_dont_know is returned. */ | |
2049 | ||
2050 | tree | |
2051 | find_loop_niter (struct loop *loop, edge *exit) | |
2052 | { | |
ca83d385 | 2053 | unsigned i; |
9771b263 | 2054 | vec<edge> exits = get_loop_exit_edges (loop); |
ca4c3169 ZD |
2055 | edge ex; |
2056 | tree niter = NULL_TREE, aniter; | |
2057 | struct tree_niter_desc desc; | |
2058 | ||
2059 | *exit = NULL; | |
9771b263 | 2060 | FOR_EACH_VEC_ELT (exits, i, ex) |
ca4c3169 | 2061 | { |
f9cc1a70 | 2062 | if (!number_of_iterations_exit (loop, ex, &desc, false)) |
ca4c3169 ZD |
2063 | continue; |
2064 | ||
6e682d7e | 2065 | if (integer_nonzerop (desc.may_be_zero)) |
ca4c3169 ZD |
2066 | { |
2067 | /* We exit in the first iteration through this exit. | |
2068 | We won't find anything better. */ | |
ff5e9a94 | 2069 | niter = build_int_cst (unsigned_type_node, 0); |
ca4c3169 ZD |
2070 | *exit = ex; |
2071 | break; | |
2072 | } | |
2073 | ||
6e682d7e | 2074 | if (!integer_zerop (desc.may_be_zero)) |
ca4c3169 ZD |
2075 | continue; |
2076 | ||
2077 | aniter = desc.niter; | |
2078 | ||
2079 | if (!niter) | |
2080 | { | |
2081 | /* Nothing recorded yet. */ | |
2082 | niter = aniter; | |
2083 | *exit = ex; | |
2084 | continue; | |
2085 | } | |
2086 | ||
2087 | /* Prefer constants, the lower the better. */ | |
2088 | if (TREE_CODE (aniter) != INTEGER_CST) | |
2089 | continue; | |
2090 | ||
2091 | if (TREE_CODE (niter) != INTEGER_CST) | |
2092 | { | |
2093 | niter = aniter; | |
2094 | *exit = ex; | |
2095 | continue; | |
2096 | } | |
2097 | ||
2098 | if (tree_int_cst_lt (aniter, niter)) | |
2099 | { | |
2100 | niter = aniter; | |
2101 | *exit = ex; | |
2102 | continue; | |
2103 | } | |
2104 | } | |
9771b263 | 2105 | exits.release (); |
ca4c3169 ZD |
2106 | |
2107 | return niter ? niter : chrec_dont_know; | |
2108 | } | |
2109 | ||
f87c9042 JH |
2110 | /* Return true if loop is known to have bounded number of iterations. */ |
2111 | ||
2112 | bool | |
2113 | finite_loop_p (struct loop *loop) | |
2114 | { | |
807e902e | 2115 | widest_int nit; |
9e3920e9 | 2116 | int flags; |
f87c9042 JH |
2117 | |
2118 | if (flag_unsafe_loop_optimizations) | |
2119 | return true; | |
9e3920e9 JJ |
2120 | flags = flags_from_decl_or_type (current_function_decl); |
2121 | if ((flags & (ECF_CONST|ECF_PURE)) && !(flags & ECF_LOOPING_CONST_OR_PURE)) | |
f87c9042 JH |
2122 | { |
2123 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2124 | fprintf (dump_file, "Found loop %i to be finite: it is within pure or const function.\n", | |
2125 | loop->num); | |
2126 | return true; | |
2127 | } | |
b8698a0f | 2128 | |
1bc60b18 JH |
2129 | if (loop->any_upper_bound |
2130 | || max_loop_iterations (loop, &nit)) | |
f87c9042 | 2131 | { |
1bc60b18 JH |
2132 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2133 | fprintf (dump_file, "Found loop %i to be finite: upper bound found.\n", | |
2134 | loop->num); | |
2135 | return true; | |
f87c9042 | 2136 | } |
1bc60b18 | 2137 | return false; |
f87c9042 JH |
2138 | } |
2139 | ||
e9eb809d ZD |
2140 | /* |
2141 | ||
2142 | Analysis of a number of iterations of a loop by a brute-force evaluation. | |
2143 | ||
2144 | */ | |
2145 | ||
2146 | /* Bound on the number of iterations we try to evaluate. */ | |
2147 | ||
2148 | #define MAX_ITERATIONS_TO_TRACK \ | |
2149 | ((unsigned) PARAM_VALUE (PARAM_MAX_ITERATIONS_TO_TRACK)) | |
2150 | ||
2151 | /* Returns the loop phi node of LOOP such that ssa name X is derived from its | |
2152 | result by a chain of operations such that all but exactly one of their | |
2153 | operands are constants. */ | |
2154 | ||
726a989a | 2155 | static gimple |
e9eb809d ZD |
2156 | chain_of_csts_start (struct loop *loop, tree x) |
2157 | { | |
726a989a | 2158 | gimple stmt = SSA_NAME_DEF_STMT (x); |
f47c96aa | 2159 | tree use; |
726a989a RB |
2160 | basic_block bb = gimple_bb (stmt); |
2161 | enum tree_code code; | |
e9eb809d ZD |
2162 | |
2163 | if (!bb | |
2164 | || !flow_bb_inside_loop_p (loop, bb)) | |
726a989a | 2165 | return NULL; |
b8698a0f | 2166 | |
726a989a | 2167 | if (gimple_code (stmt) == GIMPLE_PHI) |
e9eb809d ZD |
2168 | { |
2169 | if (bb == loop->header) | |
2170 | return stmt; | |
2171 | ||
726a989a | 2172 | return NULL; |
e9eb809d ZD |
2173 | } |
2174 | ||
100f09a5 RB |
2175 | if (gimple_code (stmt) != GIMPLE_ASSIGN |
2176 | || gimple_assign_rhs_class (stmt) == GIMPLE_TERNARY_RHS) | |
726a989a | 2177 | return NULL; |
e9eb809d | 2178 | |
726a989a RB |
2179 | code = gimple_assign_rhs_code (stmt); |
2180 | if (gimple_references_memory_p (stmt) | |
726a989a | 2181 | || TREE_CODE_CLASS (code) == tcc_reference |
5006671f RG |
2182 | || (code == ADDR_EXPR |
2183 | && !is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))) | |
726a989a | 2184 | return NULL; |
f47c96aa AM |
2185 | |
2186 | use = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
5006671f | 2187 | if (use == NULL_TREE) |
726a989a | 2188 | return NULL; |
e9eb809d | 2189 | |
f47c96aa | 2190 | return chain_of_csts_start (loop, use); |
e9eb809d ZD |
2191 | } |
2192 | ||
2193 | /* Determines whether the expression X is derived from a result of a phi node | |
2194 | in header of LOOP such that | |
2195 | ||
2196 | * the derivation of X consists only from operations with constants | |
2197 | * the initial value of the phi node is constant | |
2198 | * the value of the phi node in the next iteration can be derived from the | |
2199 | value in the current iteration by a chain of operations with constants. | |
b8698a0f | 2200 | |
726a989a | 2201 | If such phi node exists, it is returned, otherwise NULL is returned. */ |
e9eb809d | 2202 | |
726a989a | 2203 | static gimple |
e9eb809d ZD |
2204 | get_base_for (struct loop *loop, tree x) |
2205 | { | |
726a989a RB |
2206 | gimple phi; |
2207 | tree init, next; | |
e9eb809d ZD |
2208 | |
2209 | if (is_gimple_min_invariant (x)) | |
726a989a | 2210 | return NULL; |
e9eb809d ZD |
2211 | |
2212 | phi = chain_of_csts_start (loop, x); | |
2213 | if (!phi) | |
726a989a | 2214 | return NULL; |
e9eb809d ZD |
2215 | |
2216 | init = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop)); | |
2217 | next = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (loop)); | |
2218 | ||
2219 | if (TREE_CODE (next) != SSA_NAME) | |
726a989a | 2220 | return NULL; |
e9eb809d ZD |
2221 | |
2222 | if (!is_gimple_min_invariant (init)) | |
726a989a | 2223 | return NULL; |
e9eb809d ZD |
2224 | |
2225 | if (chain_of_csts_start (loop, next) != phi) | |
726a989a | 2226 | return NULL; |
e9eb809d ZD |
2227 | |
2228 | return phi; | |
2229 | } | |
2230 | ||
b8698a0f L |
2231 | /* Given an expression X, then |
2232 | ||
ed52affe | 2233 | * if X is NULL_TREE, we return the constant BASE. |
e9eb809d ZD |
2234 | * otherwise X is a SSA name, whose value in the considered loop is derived |
2235 | by a chain of operations with constant from a result of a phi node in | |
2236 | the header of the loop. Then we return value of X when the value of the | |
2237 | result of this phi node is given by the constant BASE. */ | |
2238 | ||
2239 | static tree | |
2240 | get_val_for (tree x, tree base) | |
2241 | { | |
726a989a | 2242 | gimple stmt; |
e9eb809d | 2243 | |
100f09a5 | 2244 | gcc_checking_assert (is_gimple_min_invariant (base)); |
ed52affe | 2245 | |
e9eb809d ZD |
2246 | if (!x) |
2247 | return base; | |
2248 | ||
2249 | stmt = SSA_NAME_DEF_STMT (x); | |
726a989a | 2250 | if (gimple_code (stmt) == GIMPLE_PHI) |
e9eb809d ZD |
2251 | return base; |
2252 | ||
100f09a5 | 2253 | gcc_checking_assert (is_gimple_assign (stmt)); |
726a989a RB |
2254 | |
2255 | /* STMT must be either an assignment of a single SSA name or an | |
2256 | expression involving an SSA name and a constant. Try to fold that | |
2257 | expression using the value for the SSA name. */ | |
0f336c35 RG |
2258 | if (gimple_assign_ssa_name_copy_p (stmt)) |
2259 | return get_val_for (gimple_assign_rhs1 (stmt), base); | |
2260 | else if (gimple_assign_rhs_class (stmt) == GIMPLE_UNARY_RHS | |
2261 | && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME) | |
2262 | { | |
2263 | return fold_build1 (gimple_assign_rhs_code (stmt), | |
2264 | gimple_expr_type (stmt), | |
2265 | get_val_for (gimple_assign_rhs1 (stmt), base)); | |
2266 | } | |
2267 | else if (gimple_assign_rhs_class (stmt) == GIMPLE_BINARY_RHS) | |
726a989a | 2268 | { |
0f336c35 RG |
2269 | tree rhs1 = gimple_assign_rhs1 (stmt); |
2270 | tree rhs2 = gimple_assign_rhs2 (stmt); | |
2271 | if (TREE_CODE (rhs1) == SSA_NAME) | |
2272 | rhs1 = get_val_for (rhs1, base); | |
2273 | else if (TREE_CODE (rhs2) == SSA_NAME) | |
2274 | rhs2 = get_val_for (rhs2, base); | |
2275 | else | |
2276 | gcc_unreachable (); | |
2277 | return fold_build2 (gimple_assign_rhs_code (stmt), | |
2278 | gimple_expr_type (stmt), rhs1, rhs2); | |
f47c96aa | 2279 | } |
726a989a | 2280 | else |
0f336c35 | 2281 | gcc_unreachable (); |
e9eb809d ZD |
2282 | } |
2283 | ||
726a989a | 2284 | |
e9eb809d ZD |
2285 | /* Tries to count the number of iterations of LOOP till it exits by EXIT |
2286 | by brute force -- i.e. by determining the value of the operands of the | |
2287 | condition at EXIT in first few iterations of the loop (assuming that | |
2288 | these values are constant) and determining the first one in that the | |
2289 | condition is not satisfied. Returns the constant giving the number | |
2290 | of the iterations of LOOP if successful, chrec_dont_know otherwise. */ | |
2291 | ||
2292 | tree | |
2293 | loop_niter_by_eval (struct loop *loop, edge exit) | |
2294 | { | |
726a989a RB |
2295 | tree acnd; |
2296 | tree op[2], val[2], next[2], aval[2]; | |
2297 | gimple phi, cond; | |
e9eb809d ZD |
2298 | unsigned i, j; |
2299 | enum tree_code cmp; | |
2300 | ||
2301 | cond = last_stmt (exit->src); | |
726a989a | 2302 | if (!cond || gimple_code (cond) != GIMPLE_COND) |
e9eb809d ZD |
2303 | return chrec_dont_know; |
2304 | ||
726a989a | 2305 | cmp = gimple_cond_code (cond); |
e9eb809d | 2306 | if (exit->flags & EDGE_TRUE_VALUE) |
726a989a | 2307 | cmp = invert_tree_comparison (cmp, false); |
e9eb809d | 2308 | |
e9eb809d ZD |
2309 | switch (cmp) |
2310 | { | |
2311 | case EQ_EXPR: | |
2312 | case NE_EXPR: | |
2313 | case GT_EXPR: | |
2314 | case GE_EXPR: | |
2315 | case LT_EXPR: | |
2316 | case LE_EXPR: | |
726a989a RB |
2317 | op[0] = gimple_cond_lhs (cond); |
2318 | op[1] = gimple_cond_rhs (cond); | |
e9eb809d ZD |
2319 | break; |
2320 | ||
2321 | default: | |
2322 | return chrec_dont_know; | |
2323 | } | |
2324 | ||
2325 | for (j = 0; j < 2; j++) | |
2326 | { | |
726a989a | 2327 | if (is_gimple_min_invariant (op[j])) |
e9eb809d | 2328 | { |
726a989a RB |
2329 | val[j] = op[j]; |
2330 | next[j] = NULL_TREE; | |
2331 | op[j] = NULL_TREE; | |
e9eb809d ZD |
2332 | } |
2333 | else | |
2334 | { | |
726a989a RB |
2335 | phi = get_base_for (loop, op[j]); |
2336 | if (!phi) | |
2337 | return chrec_dont_know; | |
2338 | val[j] = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop)); | |
2339 | next[j] = PHI_ARG_DEF_FROM_EDGE (phi, loop_latch_edge (loop)); | |
e9eb809d ZD |
2340 | } |
2341 | } | |
2342 | ||
6ac01510 ILT |
2343 | /* Don't issue signed overflow warnings. */ |
2344 | fold_defer_overflow_warnings (); | |
2345 | ||
e9eb809d ZD |
2346 | for (i = 0; i < MAX_ITERATIONS_TO_TRACK; i++) |
2347 | { | |
2348 | for (j = 0; j < 2; j++) | |
2349 | aval[j] = get_val_for (op[j], val[j]); | |
2350 | ||
2f133f46 | 2351 | acnd = fold_binary (cmp, boolean_type_node, aval[0], aval[1]); |
6e682d7e | 2352 | if (acnd && integer_zerop (acnd)) |
e9eb809d | 2353 | { |
6ac01510 | 2354 | fold_undefer_and_ignore_overflow_warnings (); |
e9eb809d ZD |
2355 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2356 | fprintf (dump_file, | |
2357 | "Proved that loop %d iterates %d times using brute force.\n", | |
2358 | loop->num, i); | |
7d60be94 | 2359 | return build_int_cst (unsigned_type_node, i); |
e9eb809d ZD |
2360 | } |
2361 | ||
2362 | for (j = 0; j < 2; j++) | |
ed52affe RG |
2363 | { |
2364 | val[j] = get_val_for (next[j], val[j]); | |
2365 | if (!is_gimple_min_invariant (val[j])) | |
6ac01510 ILT |
2366 | { |
2367 | fold_undefer_and_ignore_overflow_warnings (); | |
2368 | return chrec_dont_know; | |
2369 | } | |
ed52affe | 2370 | } |
e9eb809d ZD |
2371 | } |
2372 | ||
6ac01510 ILT |
2373 | fold_undefer_and_ignore_overflow_warnings (); |
2374 | ||
e9eb809d ZD |
2375 | return chrec_dont_know; |
2376 | } | |
2377 | ||
2378 | /* Finds the exit of the LOOP by that the loop exits after a constant | |
2379 | number of iterations and stores the exit edge to *EXIT. The constant | |
2380 | giving the number of iterations of LOOP is returned. The number of | |
2381 | iterations is determined using loop_niter_by_eval (i.e. by brute force | |
2382 | evaluation). If we are unable to find the exit for that loop_niter_by_eval | |
2383 | determines the number of iterations, chrec_dont_know is returned. */ | |
2384 | ||
2385 | tree | |
2386 | find_loop_niter_by_eval (struct loop *loop, edge *exit) | |
2387 | { | |
ca83d385 | 2388 | unsigned i; |
9771b263 | 2389 | vec<edge> exits = get_loop_exit_edges (loop); |
e9eb809d ZD |
2390 | edge ex; |
2391 | tree niter = NULL_TREE, aniter; | |
2392 | ||
2393 | *exit = NULL; | |
2cee1509 RG |
2394 | |
2395 | /* Loops with multiple exits are expensive to handle and less important. */ | |
2396 | if (!flag_expensive_optimizations | |
9771b263 | 2397 | && exits.length () > 1) |
f5843d08 | 2398 | { |
9771b263 | 2399 | exits.release (); |
f5843d08 RG |
2400 | return chrec_dont_know; |
2401 | } | |
2cee1509 | 2402 | |
9771b263 | 2403 | FOR_EACH_VEC_ELT (exits, i, ex) |
e9eb809d | 2404 | { |
e9eb809d ZD |
2405 | if (!just_once_each_iteration_p (loop, ex->src)) |
2406 | continue; | |
2407 | ||
2408 | aniter = loop_niter_by_eval (loop, ex); | |
ca4c3169 | 2409 | if (chrec_contains_undetermined (aniter)) |
e9eb809d ZD |
2410 | continue; |
2411 | ||
2412 | if (niter | |
ca4c3169 | 2413 | && !tree_int_cst_lt (aniter, niter)) |
e9eb809d ZD |
2414 | continue; |
2415 | ||
2416 | niter = aniter; | |
2417 | *exit = ex; | |
2418 | } | |
9771b263 | 2419 | exits.release (); |
e9eb809d ZD |
2420 | |
2421 | return niter ? niter : chrec_dont_know; | |
2422 | } | |
2423 | ||
2424 | /* | |
2425 | ||
2426 | Analysis of upper bounds on number of iterations of a loop. | |
2427 | ||
2428 | */ | |
2429 | ||
807e902e | 2430 | static widest_int derive_constant_upper_bound_ops (tree, tree, |
726a989a RB |
2431 | enum tree_code, tree); |
2432 | ||
2433 | /* Returns a constant upper bound on the value of the right-hand side of | |
2434 | an assignment statement STMT. */ | |
2435 | ||
807e902e | 2436 | static widest_int |
726a989a RB |
2437 | derive_constant_upper_bound_assign (gimple stmt) |
2438 | { | |
2439 | enum tree_code code = gimple_assign_rhs_code (stmt); | |
2440 | tree op0 = gimple_assign_rhs1 (stmt); | |
2441 | tree op1 = gimple_assign_rhs2 (stmt); | |
2442 | ||
2443 | return derive_constant_upper_bound_ops (TREE_TYPE (gimple_assign_lhs (stmt)), | |
2444 | op0, code, op1); | |
2445 | } | |
2446 | ||
0ad1d5a1 ZD |
2447 | /* Returns a constant upper bound on the value of expression VAL. VAL |
2448 | is considered to be unsigned. If its type is signed, its value must | |
b3ce5b6e | 2449 | be nonnegative. */ |
b8698a0f | 2450 | |
807e902e | 2451 | static widest_int |
726a989a RB |
2452 | derive_constant_upper_bound (tree val) |
2453 | { | |
2454 | enum tree_code code; | |
2455 | tree op0, op1; | |
2456 | ||
2457 | extract_ops_from_tree (val, &code, &op0, &op1); | |
2458 | return derive_constant_upper_bound_ops (TREE_TYPE (val), op0, code, op1); | |
2459 | } | |
2460 | ||
2461 | /* Returns a constant upper bound on the value of expression OP0 CODE OP1, | |
2462 | whose type is TYPE. The expression is considered to be unsigned. If | |
2463 | its type is signed, its value must be nonnegative. */ | |
b8698a0f | 2464 | |
807e902e | 2465 | static widest_int |
726a989a RB |
2466 | derive_constant_upper_bound_ops (tree type, tree op0, |
2467 | enum tree_code code, tree op1) | |
763f4527 | 2468 | { |
726a989a | 2469 | tree subtype, maxt; |
807e902e | 2470 | widest_int bnd, max, mmax, cst; |
726a989a | 2471 | gimple stmt; |
0ad1d5a1 ZD |
2472 | |
2473 | if (INTEGRAL_TYPE_P (type)) | |
2474 | maxt = TYPE_MAX_VALUE (type); | |
2475 | else | |
2476 | maxt = upper_bound_in_type (type, type); | |
2477 | ||
807e902e | 2478 | max = wi::to_widest (maxt); |
0ad1d5a1 | 2479 | |
726a989a | 2480 | switch (code) |
0ad1d5a1 ZD |
2481 | { |
2482 | case INTEGER_CST: | |
807e902e | 2483 | return wi::to_widest (op0); |
0ad1d5a1 | 2484 | |
1043771b | 2485 | CASE_CONVERT: |
0ad1d5a1 ZD |
2486 | subtype = TREE_TYPE (op0); |
2487 | if (!TYPE_UNSIGNED (subtype) | |
2488 | /* If TYPE is also signed, the fact that VAL is nonnegative implies | |
2489 | that OP0 is nonnegative. */ | |
2490 | && TYPE_UNSIGNED (type) | |
b3ce5b6e | 2491 | && !tree_expr_nonnegative_p (op0)) |
0ad1d5a1 ZD |
2492 | { |
2493 | /* If we cannot prove that the casted expression is nonnegative, | |
2494 | we cannot establish more useful upper bound than the precision | |
2495 | of the type gives us. */ | |
2496 | return max; | |
2497 | } | |
763f4527 | 2498 | |
0ad1d5a1 ZD |
2499 | /* We now know that op0 is an nonnegative value. Try deriving an upper |
2500 | bound for it. */ | |
b3ce5b6e | 2501 | bnd = derive_constant_upper_bound (op0); |
0ad1d5a1 ZD |
2502 | |
2503 | /* If the bound does not fit in TYPE, max. value of TYPE could be | |
2504 | attained. */ | |
807e902e | 2505 | if (wi::ltu_p (max, bnd)) |
0ad1d5a1 ZD |
2506 | return max; |
2507 | ||
2508 | return bnd; | |
2509 | ||
2510 | case PLUS_EXPR: | |
5be014d5 | 2511 | case POINTER_PLUS_EXPR: |
0ad1d5a1 | 2512 | case MINUS_EXPR: |
0ad1d5a1 | 2513 | if (TREE_CODE (op1) != INTEGER_CST |
b3ce5b6e | 2514 | || !tree_expr_nonnegative_p (op0)) |
0ad1d5a1 ZD |
2515 | return max; |
2516 | ||
20fb52af ZD |
2517 | /* Canonicalize to OP0 - CST. Consider CST to be signed, in order to |
2518 | choose the most logical way how to treat this constant regardless | |
2519 | of the signedness of the type. */ | |
807e902e | 2520 | cst = wi::sext (wi::to_widest (op1), TYPE_PRECISION (type)); |
726a989a | 2521 | if (code != MINUS_EXPR) |
27bcd47c | 2522 | cst = -cst; |
0ad1d5a1 | 2523 | |
b3ce5b6e | 2524 | bnd = derive_constant_upper_bound (op0); |
0ad1d5a1 | 2525 | |
807e902e | 2526 | if (wi::neg_p (cst)) |
0ad1d5a1 | 2527 | { |
27bcd47c | 2528 | cst = -cst; |
0ad1d5a1 | 2529 | /* Avoid CST == 0x80000... */ |
807e902e | 2530 | if (wi::neg_p (cst)) |
0ad1d5a1 ZD |
2531 | return max;; |
2532 | ||
20fb52af | 2533 | /* OP0 + CST. We need to check that |
0ad1d5a1 ZD |
2534 | BND <= MAX (type) - CST. */ |
2535 | ||
27bcd47c | 2536 | mmax -= cst; |
807e902e | 2537 | if (wi::ltu_p (bnd, max)) |
0ad1d5a1 ZD |
2538 | return max; |
2539 | ||
27bcd47c | 2540 | return bnd + cst; |
0ad1d5a1 ZD |
2541 | } |
2542 | else | |
2543 | { | |
20fb52af ZD |
2544 | /* OP0 - CST, where CST >= 0. |
2545 | ||
2546 | If TYPE is signed, we have already verified that OP0 >= 0, and we | |
2547 | know that the result is nonnegative. This implies that | |
2548 | VAL <= BND - CST. | |
2549 | ||
2550 | If TYPE is unsigned, we must additionally know that OP0 >= CST, | |
2551 | otherwise the operation underflows. | |
2552 | */ | |
2553 | ||
2554 | /* This should only happen if the type is unsigned; however, for | |
b3ce5b6e | 2555 | buggy programs that use overflowing signed arithmetics even with |
20fb52af | 2556 | -fno-wrapv, this condition may also be true for signed values. */ |
807e902e | 2557 | if (wi::ltu_p (bnd, cst)) |
0ad1d5a1 ZD |
2558 | return max; |
2559 | ||
b3ce5b6e ZD |
2560 | if (TYPE_UNSIGNED (type)) |
2561 | { | |
2562 | tree tem = fold_binary (GE_EXPR, boolean_type_node, op0, | |
807e902e | 2563 | wide_int_to_tree (type, cst)); |
b3ce5b6e ZD |
2564 | if (!tem || integer_nonzerop (tem)) |
2565 | return max; | |
2566 | } | |
20fb52af | 2567 | |
27bcd47c | 2568 | bnd -= cst; |
0ad1d5a1 ZD |
2569 | } |
2570 | ||
2571 | return bnd; | |
2572 | ||
2573 | case FLOOR_DIV_EXPR: | |
2574 | case EXACT_DIV_EXPR: | |
0ad1d5a1 ZD |
2575 | if (TREE_CODE (op1) != INTEGER_CST |
2576 | || tree_int_cst_sign_bit (op1)) | |
2577 | return max; | |
2578 | ||
b3ce5b6e | 2579 | bnd = derive_constant_upper_bound (op0); |
807e902e | 2580 | return wi::udiv_floor (bnd, wi::to_widest (op1)); |
0ad1d5a1 | 2581 | |
946e1bc7 | 2582 | case BIT_AND_EXPR: |
946e1bc7 ZD |
2583 | if (TREE_CODE (op1) != INTEGER_CST |
2584 | || tree_int_cst_sign_bit (op1)) | |
2585 | return max; | |
807e902e | 2586 | return wi::to_widest (op1); |
946e1bc7 ZD |
2587 | |
2588 | case SSA_NAME: | |
726a989a RB |
2589 | stmt = SSA_NAME_DEF_STMT (op0); |
2590 | if (gimple_code (stmt) != GIMPLE_ASSIGN | |
2591 | || gimple_assign_lhs (stmt) != op0) | |
946e1bc7 | 2592 | return max; |
726a989a | 2593 | return derive_constant_upper_bound_assign (stmt); |
946e1bc7 | 2594 | |
b8698a0f | 2595 | default: |
0ad1d5a1 ZD |
2596 | return max; |
2597 | } | |
763f4527 ZD |
2598 | } |
2599 | ||
fbd28bc3 JJ |
2600 | /* Emit a -Waggressive-loop-optimizations warning if needed. */ |
2601 | ||
2602 | static void | |
2603 | do_warn_aggressive_loop_optimizations (struct loop *loop, | |
807e902e | 2604 | widest_int i_bound, gimple stmt) |
fbd28bc3 JJ |
2605 | { |
2606 | /* Don't warn if the loop doesn't have known constant bound. */ | |
2607 | if (!loop->nb_iterations | |
2608 | || TREE_CODE (loop->nb_iterations) != INTEGER_CST | |
2609 | || !warn_aggressive_loop_optimizations | |
2610 | /* To avoid warning multiple times for the same loop, | |
2611 | only start warning when we preserve loops. */ | |
2612 | || (cfun->curr_properties & PROP_loops) == 0 | |
2613 | /* Only warn once per loop. */ | |
2614 | || loop->warned_aggressive_loop_optimizations | |
2615 | /* Only warn if undefined behavior gives us lower estimate than the | |
2616 | known constant bound. */ | |
807e902e | 2617 | || wi::cmpu (i_bound, wi::to_widest (loop->nb_iterations)) >= 0 |
fbd28bc3 JJ |
2618 | /* And undefined behavior happens unconditionally. */ |
2619 | || !dominated_by_p (CDI_DOMINATORS, loop->latch, gimple_bb (stmt))) | |
2620 | return; | |
2621 | ||
2622 | edge e = single_exit (loop); | |
2623 | if (e == NULL) | |
2624 | return; | |
2625 | ||
2626 | gimple estmt = last_stmt (e->src); | |
44398cbe PC |
2627 | if (warning_at (gimple_location (stmt), OPT_Waggressive_loop_optimizations, |
2628 | "iteration %E invokes undefined behavior", | |
807e902e KZ |
2629 | wide_int_to_tree (TREE_TYPE (loop->nb_iterations), |
2630 | i_bound))) | |
44398cbe | 2631 | inform (gimple_location (estmt), "containing loop"); |
fbd28bc3 JJ |
2632 | loop->warned_aggressive_loop_optimizations = true; |
2633 | } | |
2634 | ||
b3ce5b6e | 2635 | /* Records that AT_STMT is executed at most BOUND + 1 times in LOOP. IS_EXIT |
946e1bc7 ZD |
2636 | is true if the loop is exited immediately after STMT, and this exit |
2637 | is taken at last when the STMT is executed BOUND + 1 times. | |
fa10beec | 2638 | REALISTIC is true if BOUND is expected to be close to the real number |
9bdb685e | 2639 | of iterations. UPPER is true if we are sure the loop iterates at most |
807e902e | 2640 | BOUND times. I_BOUND is a widest_int upper estimate on BOUND. */ |
e9eb809d | 2641 | |
946e1bc7 | 2642 | static void |
807e902e | 2643 | record_estimate (struct loop *loop, tree bound, const widest_int &i_bound, |
726a989a | 2644 | gimple at_stmt, bool is_exit, bool realistic, bool upper) |
e9eb809d | 2645 | { |
807e902e | 2646 | widest_int delta; |
e9eb809d ZD |
2647 | |
2648 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2649 | { | |
946e1bc7 | 2650 | fprintf (dump_file, "Statement %s", is_exit ? "(exit)" : ""); |
726a989a | 2651 | print_gimple_stmt (dump_file, at_stmt, 0, TDF_SLIM); |
9bdb685e ZD |
2652 | fprintf (dump_file, " is %sexecuted at most ", |
2653 | upper ? "" : "probably "); | |
e9eb809d | 2654 | print_generic_expr (dump_file, bound, TDF_SLIM); |
763f4527 | 2655 | fprintf (dump_file, " (bounded by "); |
807e902e | 2656 | print_decu (i_bound, dump_file); |
946e1bc7 | 2657 | fprintf (dump_file, ") + 1 times in loop %d.\n", loop->num); |
e9eb809d ZD |
2658 | } |
2659 | ||
9bdb685e ZD |
2660 | /* If the I_BOUND is just an estimate of BOUND, it rarely is close to the |
2661 | real number of iterations. */ | |
2662 | if (TREE_CODE (bound) != INTEGER_CST) | |
2663 | realistic = false; | |
f2a1b469 | 2664 | else |
807e902e | 2665 | gcc_checking_assert (i_bound == wi::to_widest (bound)); |
9bdb685e ZD |
2666 | if (!upper && !realistic) |
2667 | return; | |
2668 | ||
2669 | /* If we have a guaranteed upper bound, record it in the appropriate | |
fbd28bc3 JJ |
2670 | list, unless this is an !is_exit bound (i.e. undefined behavior in |
2671 | at_stmt) in a loop with known constant number of iterations. */ | |
2672 | if (upper | |
2673 | && (is_exit | |
2674 | || loop->nb_iterations == NULL_TREE | |
2675 | || TREE_CODE (loop->nb_iterations) != INTEGER_CST)) | |
9bdb685e | 2676 | { |
766090c2 | 2677 | struct nb_iter_bound *elt = ggc_alloc<nb_iter_bound> (); |
9bdb685e ZD |
2678 | |
2679 | elt->bound = i_bound; | |
2680 | elt->stmt = at_stmt; | |
2681 | elt->is_exit = is_exit; | |
2682 | elt->next = loop->bounds; | |
2683 | loop->bounds = elt; | |
2684 | } | |
2685 | ||
cd0f6278 JH |
2686 | /* If statement is executed on every path to the loop latch, we can directly |
2687 | infer the upper bound on the # of iterations of the loop. */ | |
2688 | if (!dominated_by_p (CDI_DOMINATORS, loop->latch, gimple_bb (at_stmt))) | |
2689 | return; | |
2690 | ||
9bdb685e | 2691 | /* Update the number of iteration estimates according to the bound. |
05322355 JH |
2692 | If at_stmt is an exit then the loop latch is executed at most BOUND times, |
2693 | otherwise it can be executed BOUND + 1 times. We will lower the estimate | |
2694 | later if such statement must be executed on last iteration */ | |
2695 | if (is_exit) | |
807e902e | 2696 | delta = 0; |
9bdb685e | 2697 | else |
807e902e KZ |
2698 | delta = 1; |
2699 | widest_int new_i_bound = i_bound + delta; | |
9bdb685e | 2700 | |
7fa7289d | 2701 | /* If an overflow occurred, ignore the result. */ |
807e902e | 2702 | if (wi::ltu_p (new_i_bound, delta)) |
9bdb685e ZD |
2703 | return; |
2704 | ||
fbd28bc3 | 2705 | if (upper && !is_exit) |
807e902e KZ |
2706 | do_warn_aggressive_loop_optimizations (loop, new_i_bound, at_stmt); |
2707 | record_niter_bound (loop, new_i_bound, realistic, upper); | |
e9eb809d ZD |
2708 | } |
2709 | ||
946e1bc7 ZD |
2710 | /* Record the estimate on number of iterations of LOOP based on the fact that |
2711 | the induction variable BASE + STEP * i evaluated in STMT does not wrap and | |
9bdb685e ZD |
2712 | its values belong to the range <LOW, HIGH>. REALISTIC is true if the |
2713 | estimated number of iterations is expected to be close to the real one. | |
2714 | UPPER is true if we are sure the induction variable does not wrap. */ | |
946e1bc7 ZD |
2715 | |
2716 | static void | |
726a989a | 2717 | record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple stmt, |
9bdb685e | 2718 | tree low, tree high, bool realistic, bool upper) |
946e1bc7 ZD |
2719 | { |
2720 | tree niter_bound, extreme, delta; | |
2721 | tree type = TREE_TYPE (base), unsigned_type; | |
2722 | ||
6e682d7e | 2723 | if (TREE_CODE (step) != INTEGER_CST || integer_zerop (step)) |
946e1bc7 ZD |
2724 | return; |
2725 | ||
2726 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2727 | { | |
2728 | fprintf (dump_file, "Induction variable ("); | |
2729 | print_generic_expr (dump_file, TREE_TYPE (base), TDF_SLIM); | |
2730 | fprintf (dump_file, ") "); | |
2731 | print_generic_expr (dump_file, base, TDF_SLIM); | |
2732 | fprintf (dump_file, " + "); | |
2733 | print_generic_expr (dump_file, step, TDF_SLIM); | |
2734 | fprintf (dump_file, " * iteration does not wrap in statement "); | |
726a989a | 2735 | print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
946e1bc7 ZD |
2736 | fprintf (dump_file, " in loop %d.\n", loop->num); |
2737 | } | |
2738 | ||
2739 | unsigned_type = unsigned_type_for (type); | |
2740 | base = fold_convert (unsigned_type, base); | |
2741 | step = fold_convert (unsigned_type, step); | |
2742 | ||
2743 | if (tree_int_cst_sign_bit (step)) | |
2744 | { | |
2745 | extreme = fold_convert (unsigned_type, low); | |
2746 | if (TREE_CODE (base) != INTEGER_CST) | |
2747 | base = fold_convert (unsigned_type, high); | |
2748 | delta = fold_build2 (MINUS_EXPR, unsigned_type, base, extreme); | |
2749 | step = fold_build1 (NEGATE_EXPR, unsigned_type, step); | |
2750 | } | |
2751 | else | |
2752 | { | |
2753 | extreme = fold_convert (unsigned_type, high); | |
2754 | if (TREE_CODE (base) != INTEGER_CST) | |
2755 | base = fold_convert (unsigned_type, low); | |
2756 | delta = fold_build2 (MINUS_EXPR, unsigned_type, extreme, base); | |
2757 | } | |
2758 | ||
2759 | /* STMT is executed at most NITER_BOUND + 1 times, since otherwise the value | |
2760 | would get out of the range. */ | |
2761 | niter_bound = fold_build2 (FLOOR_DIV_EXPR, unsigned_type, delta, step); | |
807e902e | 2762 | widest_int max = derive_constant_upper_bound (niter_bound); |
9bdb685e | 2763 | record_estimate (loop, niter_bound, max, stmt, false, realistic, upper); |
4839cb59 ZD |
2764 | } |
2765 | ||
946e1bc7 | 2766 | /* Determine information about number of iterations a LOOP from the index |
ac84e05e ZD |
2767 | IDX of a data reference accessed in STMT. RELIABLE is true if STMT is |
2768 | guaranteed to be executed in every iteration of LOOP. Callback for | |
2769 | for_each_index. */ | |
946e1bc7 ZD |
2770 | |
2771 | struct ilb_data | |
2772 | { | |
2773 | struct loop *loop; | |
726a989a | 2774 | gimple stmt; |
946e1bc7 ZD |
2775 | }; |
2776 | ||
2777 | static bool | |
2778 | idx_infer_loop_bounds (tree base, tree *idx, void *dta) | |
2779 | { | |
c22940cd | 2780 | struct ilb_data *data = (struct ilb_data *) dta; |
946e1bc7 ZD |
2781 | tree ev, init, step; |
2782 | tree low, high, type, next; | |
cd0f6278 | 2783 | bool sign, upper = true, at_end = false; |
946e1bc7 | 2784 | struct loop *loop = data->loop; |
870ca331 | 2785 | bool reliable = true; |
946e1bc7 | 2786 | |
9bdb685e | 2787 | if (TREE_CODE (base) != ARRAY_REF) |
946e1bc7 ZD |
2788 | return true; |
2789 | ||
9bdb685e ZD |
2790 | /* For arrays at the end of the structure, we are not guaranteed that they |
2791 | do not really extend over their declared size. However, for arrays of | |
2792 | size greater than one, this is unlikely to be intended. */ | |
2793 | if (array_at_struct_end_p (base)) | |
ac84e05e ZD |
2794 | { |
2795 | at_end = true; | |
2796 | upper = false; | |
2797 | } | |
9bdb685e | 2798 | |
8b679c9b RB |
2799 | struct loop *dloop = loop_containing_stmt (data->stmt); |
2800 | if (!dloop) | |
2801 | return true; | |
2802 | ||
2803 | ev = analyze_scalar_evolution (dloop, *idx); | |
2804 | ev = instantiate_parameters (loop, ev); | |
946e1bc7 ZD |
2805 | init = initial_condition (ev); |
2806 | step = evolution_part_in_loop_num (ev, loop->num); | |
2807 | ||
2808 | if (!init | |
2809 | || !step | |
2810 | || TREE_CODE (step) != INTEGER_CST | |
6e682d7e | 2811 | || integer_zerop (step) |
946e1bc7 ZD |
2812 | || tree_contains_chrecs (init, NULL) |
2813 | || chrec_contains_symbols_defined_in_loop (init, loop->num)) | |
2814 | return true; | |
2815 | ||
2816 | low = array_ref_low_bound (base); | |
2817 | high = array_ref_up_bound (base); | |
b8698a0f | 2818 | |
946e1bc7 ZD |
2819 | /* The case of nonconstant bounds could be handled, but it would be |
2820 | complicated. */ | |
2821 | if (TREE_CODE (low) != INTEGER_CST | |
2822 | || !high | |
2823 | || TREE_CODE (high) != INTEGER_CST) | |
2824 | return true; | |
2825 | sign = tree_int_cst_sign_bit (step); | |
2826 | type = TREE_TYPE (step); | |
9bdb685e ZD |
2827 | |
2828 | /* The array of length 1 at the end of a structure most likely extends | |
2829 | beyond its bounds. */ | |
ac84e05e | 2830 | if (at_end |
9bdb685e ZD |
2831 | && operand_equal_p (low, high, 0)) |
2832 | return true; | |
2833 | ||
946e1bc7 ZD |
2834 | /* In case the relevant bound of the array does not fit in type, or |
2835 | it does, but bound + step (in type) still belongs into the range of the | |
2836 | array, the index may wrap and still stay within the range of the array | |
2837 | (consider e.g. if the array is indexed by the full range of | |
2838 | unsigned char). | |
2839 | ||
2840 | To make things simpler, we require both bounds to fit into type, although | |
2f8e468b | 2841 | there are cases where this would not be strictly necessary. */ |
946e1bc7 ZD |
2842 | if (!int_fits_type_p (high, type) |
2843 | || !int_fits_type_p (low, type)) | |
2844 | return true; | |
2845 | low = fold_convert (type, low); | |
2846 | high = fold_convert (type, high); | |
2847 | ||
2848 | if (sign) | |
2849 | next = fold_binary (PLUS_EXPR, type, low, step); | |
2850 | else | |
2851 | next = fold_binary (PLUS_EXPR, type, high, step); | |
b8698a0f | 2852 | |
946e1bc7 ZD |
2853 | if (tree_int_cst_compare (low, next) <= 0 |
2854 | && tree_int_cst_compare (next, high) <= 0) | |
2855 | return true; | |
2856 | ||
870ca331 JH |
2857 | /* If access is not executed on every iteration, we must ensure that overlow may |
2858 | not make the access valid later. */ | |
2859 | if (!dominated_by_p (CDI_DOMINATORS, loop->latch, gimple_bb (data->stmt)) | |
2860 | && scev_probably_wraps_p (initial_condition_in_loop_num (ev, loop->num), | |
2861 | step, data->stmt, loop, true)) | |
2862 | reliable = false; | |
2863 | ||
2864 | record_nonwrapping_iv (loop, init, step, data->stmt, low, high, reliable, upper); | |
946e1bc7 ZD |
2865 | return true; |
2866 | } | |
2867 | ||
2868 | /* Determine information about number of iterations a LOOP from the bounds | |
ac84e05e ZD |
2869 | of arrays in the data reference REF accessed in STMT. RELIABLE is true if |
2870 | STMT is guaranteed to be executed in every iteration of LOOP.*/ | |
946e1bc7 ZD |
2871 | |
2872 | static void | |
cd0f6278 | 2873 | infer_loop_bounds_from_ref (struct loop *loop, gimple stmt, tree ref) |
946e1bc7 ZD |
2874 | { |
2875 | struct ilb_data data; | |
2876 | ||
2877 | data.loop = loop; | |
2878 | data.stmt = stmt; | |
2879 | for_each_index (&ref, idx_infer_loop_bounds, &data); | |
2880 | } | |
2881 | ||
2882 | /* Determine information about number of iterations of a LOOP from the way | |
ac84e05e ZD |
2883 | arrays are used in STMT. RELIABLE is true if STMT is guaranteed to be |
2884 | executed in every iteration of LOOP. */ | |
946e1bc7 ZD |
2885 | |
2886 | static void | |
cd0f6278 | 2887 | infer_loop_bounds_from_array (struct loop *loop, gimple stmt) |
946e1bc7 | 2888 | { |
726a989a | 2889 | if (is_gimple_assign (stmt)) |
946e1bc7 | 2890 | { |
726a989a RB |
2891 | tree op0 = gimple_assign_lhs (stmt); |
2892 | tree op1 = gimple_assign_rhs1 (stmt); | |
946e1bc7 ZD |
2893 | |
2894 | /* For each memory access, analyze its access function | |
2895 | and record a bound on the loop iteration domain. */ | |
2896 | if (REFERENCE_CLASS_P (op0)) | |
cd0f6278 | 2897 | infer_loop_bounds_from_ref (loop, stmt, op0); |
946e1bc7 ZD |
2898 | |
2899 | if (REFERENCE_CLASS_P (op1)) | |
cd0f6278 | 2900 | infer_loop_bounds_from_ref (loop, stmt, op1); |
946e1bc7 | 2901 | } |
726a989a | 2902 | else if (is_gimple_call (stmt)) |
946e1bc7 | 2903 | { |
726a989a RB |
2904 | tree arg, lhs; |
2905 | unsigned i, n = gimple_call_num_args (stmt); | |
946e1bc7 | 2906 | |
726a989a RB |
2907 | lhs = gimple_call_lhs (stmt); |
2908 | if (lhs && REFERENCE_CLASS_P (lhs)) | |
cd0f6278 | 2909 | infer_loop_bounds_from_ref (loop, stmt, lhs); |
726a989a RB |
2910 | |
2911 | for (i = 0; i < n; i++) | |
2912 | { | |
2913 | arg = gimple_call_arg (stmt, i); | |
2914 | if (REFERENCE_CLASS_P (arg)) | |
cd0f6278 | 2915 | infer_loop_bounds_from_ref (loop, stmt, arg); |
726a989a | 2916 | } |
946e1bc7 ZD |
2917 | } |
2918 | } | |
2919 | ||
bc69f7ff TV |
2920 | /* Determine information about number of iterations of a LOOP from the fact |
2921 | that pointer arithmetics in STMT does not overflow. */ | |
2922 | ||
2923 | static void | |
2924 | infer_loop_bounds_from_pointer_arith (struct loop *loop, gimple stmt) | |
2925 | { | |
2926 | tree def, base, step, scev, type, low, high; | |
2927 | tree var, ptr; | |
2928 | ||
2929 | if (!is_gimple_assign (stmt) | |
2930 | || gimple_assign_rhs_code (stmt) != POINTER_PLUS_EXPR) | |
2931 | return; | |
2932 | ||
2933 | def = gimple_assign_lhs (stmt); | |
2934 | if (TREE_CODE (def) != SSA_NAME) | |
2935 | return; | |
2936 | ||
2937 | type = TREE_TYPE (def); | |
2938 | if (!nowrap_type_p (type)) | |
2939 | return; | |
2940 | ||
2941 | ptr = gimple_assign_rhs1 (stmt); | |
2942 | if (!expr_invariant_in_loop_p (loop, ptr)) | |
2943 | return; | |
2944 | ||
2945 | var = gimple_assign_rhs2 (stmt); | |
2946 | if (TYPE_PRECISION (type) != TYPE_PRECISION (TREE_TYPE (var))) | |
2947 | return; | |
2948 | ||
2949 | scev = instantiate_parameters (loop, analyze_scalar_evolution (loop, def)); | |
2950 | if (chrec_contains_undetermined (scev)) | |
2951 | return; | |
2952 | ||
2953 | base = initial_condition_in_loop_num (scev, loop->num); | |
2954 | step = evolution_part_in_loop_num (scev, loop->num); | |
2955 | ||
2956 | if (!base || !step | |
2957 | || TREE_CODE (step) != INTEGER_CST | |
2958 | || tree_contains_chrecs (base, NULL) | |
2959 | || chrec_contains_symbols_defined_in_loop (base, loop->num)) | |
2960 | return; | |
2961 | ||
2962 | low = lower_bound_in_type (type, type); | |
2963 | high = upper_bound_in_type (type, type); | |
2964 | ||
0703f020 TV |
2965 | /* In C, pointer arithmetic p + 1 cannot use a NULL pointer, and p - 1 cannot |
2966 | produce a NULL pointer. The contrary would mean NULL points to an object, | |
2967 | while NULL is supposed to compare unequal with the address of all objects. | |
2968 | Furthermore, p + 1 cannot produce a NULL pointer and p - 1 cannot use a | |
2969 | NULL pointer since that would mean wrapping, which we assume here not to | |
2970 | happen. So, we can exclude NULL from the valid range of pointer | |
2971 | arithmetic. */ | |
2972 | if (flag_delete_null_pointer_checks && int_cst_value (low) == 0) | |
2973 | low = build_int_cstu (TREE_TYPE (low), TYPE_ALIGN_UNIT (TREE_TYPE (type))); | |
2974 | ||
bc69f7ff TV |
2975 | record_nonwrapping_iv (loop, base, step, stmt, low, high, false, true); |
2976 | } | |
2977 | ||
946e1bc7 ZD |
2978 | /* Determine information about number of iterations of a LOOP from the fact |
2979 | that signed arithmetics in STMT does not overflow. */ | |
2980 | ||
2981 | static void | |
726a989a | 2982 | infer_loop_bounds_from_signedness (struct loop *loop, gimple stmt) |
946e1bc7 ZD |
2983 | { |
2984 | tree def, base, step, scev, type, low, high; | |
2985 | ||
726a989a | 2986 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
946e1bc7 ZD |
2987 | return; |
2988 | ||
726a989a | 2989 | def = gimple_assign_lhs (stmt); |
946e1bc7 ZD |
2990 | |
2991 | if (TREE_CODE (def) != SSA_NAME) | |
2992 | return; | |
2993 | ||
2994 | type = TREE_TYPE (def); | |
2995 | if (!INTEGRAL_TYPE_P (type) | |
eeef0e45 | 2996 | || !TYPE_OVERFLOW_UNDEFINED (type)) |
946e1bc7 ZD |
2997 | return; |
2998 | ||
2999 | scev = instantiate_parameters (loop, analyze_scalar_evolution (loop, def)); | |
3000 | if (chrec_contains_undetermined (scev)) | |
3001 | return; | |
3002 | ||
3003 | base = initial_condition_in_loop_num (scev, loop->num); | |
3004 | step = evolution_part_in_loop_num (scev, loop->num); | |
3005 | ||
3006 | if (!base || !step | |
3007 | || TREE_CODE (step) != INTEGER_CST | |
3008 | || tree_contains_chrecs (base, NULL) | |
3009 | || chrec_contains_symbols_defined_in_loop (base, loop->num)) | |
3010 | return; | |
3011 | ||
3012 | low = lower_bound_in_type (type, type); | |
3013 | high = upper_bound_in_type (type, type); | |
3014 | ||
9bdb685e | 3015 | record_nonwrapping_iv (loop, base, step, stmt, low, high, false, true); |
946e1bc7 ZD |
3016 | } |
3017 | ||
d7770457 SP |
3018 | /* The following analyzers are extracting informations on the bounds |
3019 | of LOOP from the following undefined behaviors: | |
3020 | ||
3021 | - data references should not access elements over the statically | |
3022 | allocated size, | |
3023 | ||
3024 | - signed variables should not overflow when flag_wrapv is not set. | |
3025 | */ | |
3026 | ||
3027 | static void | |
3028 | infer_loop_bounds_from_undefined (struct loop *loop) | |
3029 | { | |
3030 | unsigned i; | |
946e1bc7 | 3031 | basic_block *bbs; |
726a989a | 3032 | gimple_stmt_iterator bsi; |
946e1bc7 | 3033 | basic_block bb; |
ac84e05e | 3034 | bool reliable; |
b8698a0f | 3035 | |
d7770457 SP |
3036 | bbs = get_loop_body (loop); |
3037 | ||
3038 | for (i = 0; i < loop->num_nodes; i++) | |
3039 | { | |
3040 | bb = bbs[i]; | |
3041 | ||
946e1bc7 | 3042 | /* If BB is not executed in each iteration of the loop, we cannot |
ac84e05e | 3043 | use the operations in it to infer reliable upper bound on the |
cd0f6278 JH |
3044 | # of iterations of the loop. However, we can use it as a guess. |
3045 | Reliable guesses come only from array bounds. */ | |
ac84e05e | 3046 | reliable = dominated_by_p (CDI_DOMINATORS, loop->latch, bb); |
946e1bc7 | 3047 | |
726a989a | 3048 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
946e1bc7 | 3049 | { |
726a989a | 3050 | gimple stmt = gsi_stmt (bsi); |
d7770457 | 3051 | |
cd0f6278 | 3052 | infer_loop_bounds_from_array (loop, stmt); |
ac84e05e ZD |
3053 | |
3054 | if (reliable) | |
bc69f7ff TV |
3055 | { |
3056 | infer_loop_bounds_from_signedness (loop, stmt); | |
3057 | infer_loop_bounds_from_pointer_arith (loop, stmt); | |
3058 | } | |
946e1bc7 ZD |
3059 | } |
3060 | ||
d7770457 SP |
3061 | } |
3062 | ||
3063 | free (bbs); | |
3064 | } | |
3065 | ||
807e902e | 3066 | /* Compare wide ints, callback for qsort. */ |
73ddf95b | 3067 | |
71343877 | 3068 | static int |
807e902e | 3069 | wide_int_cmp (const void *p1, const void *p2) |
73ddf95b | 3070 | { |
807e902e KZ |
3071 | const widest_int *d1 = (const widest_int *) p1; |
3072 | const widest_int *d2 = (const widest_int *) p2; | |
3073 | return wi::cmpu (*d1, *d2); | |
73ddf95b JH |
3074 | } |
3075 | ||
3076 | /* Return index of BOUND in BOUNDS array sorted in increasing order. | |
3077 | Lookup by binary search. */ | |
3078 | ||
71343877 | 3079 | static int |
807e902e | 3080 | bound_index (vec<widest_int> bounds, const widest_int &bound) |
73ddf95b | 3081 | { |
9771b263 | 3082 | unsigned int end = bounds.length (); |
73ddf95b JH |
3083 | unsigned int begin = 0; |
3084 | ||
3085 | /* Find a matching index by means of a binary search. */ | |
3086 | while (begin != end) | |
3087 | { | |
3088 | unsigned int middle = (begin + end) / 2; | |
807e902e | 3089 | widest_int index = bounds[middle]; |
73ddf95b JH |
3090 | |
3091 | if (index == bound) | |
3092 | return middle; | |
807e902e | 3093 | else if (wi::ltu_p (index, bound)) |
73ddf95b JH |
3094 | begin = middle + 1; |
3095 | else | |
3096 | end = middle; | |
3097 | } | |
3098 | gcc_unreachable (); | |
3099 | } | |
3100 | ||
73ddf95b JH |
3101 | /* We recorded loop bounds only for statements dominating loop latch (and thus |
3102 | executed each loop iteration). If there are any bounds on statements not | |
3103 | dominating the loop latch we can improve the estimate by walking the loop | |
3104 | body and seeing if every path from loop header to loop latch contains | |
3105 | some bounded statement. */ | |
3106 | ||
3107 | static void | |
3108 | discover_iteration_bound_by_body_walk (struct loop *loop) | |
3109 | { | |
3110 | pointer_map_t *bb_bounds; | |
3111 | struct nb_iter_bound *elt; | |
807e902e | 3112 | vec<widest_int> bounds = vNULL; |
b4f9786b JJ |
3113 | vec<vec<basic_block> > queues = vNULL; |
3114 | vec<basic_block> queue = vNULL; | |
73ddf95b JH |
3115 | ptrdiff_t queue_index; |
3116 | ptrdiff_t latch_index = 0; | |
3117 | pointer_map_t *block_priority; | |
3118 | ||
3119 | /* Discover what bounds may interest us. */ | |
3120 | for (elt = loop->bounds; elt; elt = elt->next) | |
3121 | { | |
807e902e | 3122 | widest_int bound = elt->bound; |
73ddf95b JH |
3123 | |
3124 | /* Exit terminates loop at given iteration, while non-exits produce undefined | |
3125 | effect on the next iteration. */ | |
3126 | if (!elt->is_exit) | |
4c052539 | 3127 | { |
807e902e | 3128 | bound += 1; |
4c052539 | 3129 | /* If an overflow occurred, ignore the result. */ |
807e902e | 3130 | if (bound == 0) |
4c052539 JJ |
3131 | continue; |
3132 | } | |
73ddf95b JH |
3133 | |
3134 | if (!loop->any_upper_bound | |
807e902e | 3135 | || wi::ltu_p (bound, loop->nb_iterations_upper_bound)) |
9771b263 | 3136 | bounds.safe_push (bound); |
73ddf95b JH |
3137 | } |
3138 | ||
3139 | /* Exit early if there is nothing to do. */ | |
9771b263 | 3140 | if (!bounds.exists ()) |
73ddf95b JH |
3141 | return; |
3142 | ||
3143 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3144 | fprintf (dump_file, " Trying to walk loop body to reduce the bound.\n"); | |
3145 | ||
3146 | /* Sort the bounds in decreasing order. */ | |
75509ba2 | 3147 | bounds.qsort (wide_int_cmp); |
73ddf95b JH |
3148 | |
3149 | /* For every basic block record the lowest bound that is guaranteed to | |
3150 | terminate the loop. */ | |
3151 | ||
3152 | bb_bounds = pointer_map_create (); | |
3153 | for (elt = loop->bounds; elt; elt = elt->next) | |
3154 | { | |
807e902e | 3155 | widest_int bound = elt->bound; |
73ddf95b | 3156 | if (!elt->is_exit) |
4c052539 | 3157 | { |
807e902e | 3158 | bound += 1; |
4c052539 | 3159 | /* If an overflow occurred, ignore the result. */ |
807e902e | 3160 | if (bound == 0) |
4c052539 JJ |
3161 | continue; |
3162 | } | |
73ddf95b JH |
3163 | |
3164 | if (!loop->any_upper_bound | |
807e902e | 3165 | || wi::ltu_p (bound, loop->nb_iterations_upper_bound)) |
73ddf95b JH |
3166 | { |
3167 | ptrdiff_t index = bound_index (bounds, bound); | |
3168 | void **entry = pointer_map_contains (bb_bounds, | |
3169 | gimple_bb (elt->stmt)); | |
3170 | if (!entry) | |
3171 | *pointer_map_insert (bb_bounds, | |
3172 | gimple_bb (elt->stmt)) = (void *)index; | |
3173 | else if ((ptrdiff_t)*entry > index) | |
3174 | *entry = (void *)index; | |
3175 | } | |
3176 | } | |
3177 | ||
3178 | block_priority = pointer_map_create (); | |
3179 | ||
3180 | /* Perform shortest path discovery loop->header ... loop->latch. | |
3181 | ||
3182 | The "distance" is given by the smallest loop bound of basic block | |
3183 | present in the path and we look for path with largest smallest bound | |
3184 | on it. | |
3185 | ||
b4f9786b | 3186 | To avoid the need for fibonacci heap on double ints we simply compress |
73ddf95b JH |
3187 | double ints into indexes to BOUNDS array and then represent the queue |
3188 | as arrays of queues for every index. | |
9771b263 | 3189 | Index of BOUNDS.length() means that the execution of given BB has |
73ddf95b JH |
3190 | no bounds determined. |
3191 | ||
3192 | VISITED is a pointer map translating basic block into smallest index | |
3193 | it was inserted into the priority queue with. */ | |
3194 | latch_index = -1; | |
3195 | ||
3196 | /* Start walk in loop header with index set to infinite bound. */ | |
9771b263 DN |
3197 | queue_index = bounds.length (); |
3198 | queues.safe_grow_cleared (queue_index + 1); | |
3199 | queue.safe_push (loop->header); | |
3200 | queues[queue_index] = queue; | |
73ddf95b JH |
3201 | *pointer_map_insert (block_priority, loop->header) = (void *)queue_index; |
3202 | ||
3203 | for (; queue_index >= 0; queue_index--) | |
3204 | { | |
3205 | if (latch_index < queue_index) | |
3206 | { | |
9771b263 | 3207 | while (queues[queue_index].length ()) |
73ddf95b JH |
3208 | { |
3209 | basic_block bb; | |
3210 | ptrdiff_t bound_index = queue_index; | |
3211 | void **entry; | |
3212 | edge e; | |
3213 | edge_iterator ei; | |
3214 | ||
9771b263 DN |
3215 | queue = queues[queue_index]; |
3216 | bb = queue.pop (); | |
73ddf95b JH |
3217 | |
3218 | /* OK, we later inserted the BB with lower priority, skip it. */ | |
3219 | if ((ptrdiff_t)*pointer_map_contains (block_priority, bb) > queue_index) | |
3220 | continue; | |
3221 | ||
3222 | /* See if we can improve the bound. */ | |
3223 | entry = pointer_map_contains (bb_bounds, bb); | |
3224 | if (entry && (ptrdiff_t)*entry < bound_index) | |
3225 | bound_index = (ptrdiff_t)*entry; | |
3226 | ||
3227 | /* Insert succesors into the queue, watch for latch edge | |
3228 | and record greatest index we saw. */ | |
3229 | FOR_EACH_EDGE (e, ei, bb->succs) | |
3230 | { | |
3231 | bool insert = false; | |
3232 | void **entry; | |
3233 | ||
3234 | if (loop_exit_edge_p (loop, e)) | |
3235 | continue; | |
3236 | ||
3237 | if (e == loop_latch_edge (loop) | |
3238 | && latch_index < bound_index) | |
3239 | latch_index = bound_index; | |
3240 | else if (!(entry = pointer_map_contains (block_priority, e->dest))) | |
3241 | { | |
3242 | insert = true; | |
3243 | *pointer_map_insert (block_priority, e->dest) = (void *)bound_index; | |
3244 | } | |
3245 | else if ((ptrdiff_t)*entry < bound_index) | |
3246 | { | |
3247 | insert = true; | |
3248 | *entry = (void *)bound_index; | |
3249 | } | |
3250 | ||
3251 | if (insert) | |
b4f9786b | 3252 | queues[bound_index].safe_push (e->dest); |
73ddf95b JH |
3253 | } |
3254 | } | |
3255 | } | |
b4f9786b | 3256 | queues[queue_index].release (); |
73ddf95b JH |
3257 | } |
3258 | ||
3259 | gcc_assert (latch_index >= 0); | |
9771b263 | 3260 | if ((unsigned)latch_index < bounds.length ()) |
73ddf95b JH |
3261 | { |
3262 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3263 | { | |
3264 | fprintf (dump_file, "Found better loop bound "); | |
807e902e | 3265 | print_decu (bounds[latch_index], dump_file); |
73ddf95b JH |
3266 | fprintf (dump_file, "\n"); |
3267 | } | |
9771b263 | 3268 | record_niter_bound (loop, bounds[latch_index], false, true); |
73ddf95b JH |
3269 | } |
3270 | ||
9771b263 | 3271 | queues.release (); |
b4f9786b | 3272 | bounds.release (); |
73ddf95b JH |
3273 | pointer_map_destroy (bb_bounds); |
3274 | pointer_map_destroy (block_priority); | |
3275 | } | |
3276 | ||
05322355 JH |
3277 | /* See if every path cross the loop goes through a statement that is known |
3278 | to not execute at the last iteration. In that case we can decrese iteration | |
3279 | count by 1. */ | |
3280 | ||
3281 | static void | |
3282 | maybe_lower_iteration_bound (struct loop *loop) | |
3283 | { | |
0450d718 | 3284 | pointer_set_t *not_executed_last_iteration = NULL; |
05322355 JH |
3285 | struct nb_iter_bound *elt; |
3286 | bool found_exit = false; | |
6e1aa848 | 3287 | vec<basic_block> queue = vNULL; |
05322355 JH |
3288 | bitmap visited; |
3289 | ||
3290 | /* Collect all statements with interesting (i.e. lower than | |
3291 | nb_iterations_upper_bound) bound on them. | |
3292 | ||
3293 | TODO: Due to the way record_estimate choose estimates to store, the bounds | |
3294 | will be always nb_iterations_upper_bound-1. We can change this to record | |
3295 | also statements not dominating the loop latch and update the walk bellow | |
3296 | to the shortest path algorthm. */ | |
3297 | for (elt = loop->bounds; elt; elt = elt->next) | |
3298 | { | |
3299 | if (!elt->is_exit | |
807e902e | 3300 | && wi::ltu_p (elt->bound, loop->nb_iterations_upper_bound)) |
05322355 JH |
3301 | { |
3302 | if (!not_executed_last_iteration) | |
3303 | not_executed_last_iteration = pointer_set_create (); | |
3304 | pointer_set_insert (not_executed_last_iteration, elt->stmt); | |
3305 | } | |
3306 | } | |
3307 | if (!not_executed_last_iteration) | |
3308 | return; | |
3309 | ||
3310 | /* Start DFS walk in the loop header and see if we can reach the | |
3311 | loop latch or any of the exits (including statements with side | |
3312 | effects that may terminate the loop otherwise) without visiting | |
3313 | any of the statements known to have undefined effect on the last | |
3314 | iteration. */ | |
9771b263 | 3315 | queue.safe_push (loop->header); |
05322355 JH |
3316 | visited = BITMAP_ALLOC (NULL); |
3317 | bitmap_set_bit (visited, loop->header->index); | |
3318 | found_exit = false; | |
3319 | ||
3320 | do | |
3321 | { | |
9771b263 | 3322 | basic_block bb = queue.pop (); |
05322355 JH |
3323 | gimple_stmt_iterator gsi; |
3324 | bool stmt_found = false; | |
3325 | ||
3326 | /* Loop for possible exits and statements bounding the execution. */ | |
3327 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
3328 | { | |
3329 | gimple stmt = gsi_stmt (gsi); | |
3330 | if (pointer_set_contains (not_executed_last_iteration, stmt)) | |
3331 | { | |
3332 | stmt_found = true; | |
3333 | break; | |
3334 | } | |
3335 | if (gimple_has_side_effects (stmt)) | |
3336 | { | |
3337 | found_exit = true; | |
3338 | break; | |
3339 | } | |
3340 | } | |
3341 | if (found_exit) | |
3342 | break; | |
3343 | ||
3344 | /* If no bounding statement is found, continue the walk. */ | |
3345 | if (!stmt_found) | |
3346 | { | |
3347 | edge e; | |
3348 | edge_iterator ei; | |
3349 | ||
3350 | FOR_EACH_EDGE (e, ei, bb->succs) | |
3351 | { | |
3352 | if (loop_exit_edge_p (loop, e) | |
3353 | || e == loop_latch_edge (loop)) | |
3354 | { | |
3355 | found_exit = true; | |
3356 | break; | |
3357 | } | |
3358 | if (bitmap_set_bit (visited, e->dest->index)) | |
9771b263 | 3359 | queue.safe_push (e->dest); |
05322355 JH |
3360 | } |
3361 | } | |
3362 | } | |
9771b263 | 3363 | while (queue.length () && !found_exit); |
05322355 JH |
3364 | |
3365 | /* If every path through the loop reach bounding statement before exit, | |
3366 | then we know the last iteration of the loop will have undefined effect | |
3367 | and we can decrease number of iterations. */ | |
3368 | ||
3369 | if (!found_exit) | |
3370 | { | |
3371 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3372 | fprintf (dump_file, "Reducing loop iteration estimate by 1; " | |
3373 | "undefined statement must be executed at the last iteration.\n"); | |
807e902e | 3374 | record_niter_bound (loop, loop->nb_iterations_upper_bound - 1, |
05322355 JH |
3375 | false, true); |
3376 | } | |
3377 | BITMAP_FREE (visited); | |
9771b263 | 3378 | queue.release (); |
a344216b | 3379 | pointer_set_destroy (not_executed_last_iteration); |
05322355 JH |
3380 | } |
3381 | ||
e3488283 RG |
3382 | /* Records estimates on numbers of iterations of LOOP. If USE_UNDEFINED_P |
3383 | is true also use estimates derived from undefined behavior. */ | |
e9eb809d | 3384 | |
71343877 | 3385 | static void |
421e6082 | 3386 | estimate_numbers_of_iterations_loop (struct loop *loop) |
e9eb809d | 3387 | { |
9771b263 | 3388 | vec<edge> exits; |
e9eb809d | 3389 | tree niter, type; |
ca83d385 | 3390 | unsigned i; |
e9eb809d | 3391 | struct tree_niter_desc niter_desc; |
ca83d385 | 3392 | edge ex; |
807e902e | 3393 | widest_int bound; |
f9bf4777 | 3394 | edge likely_exit; |
e9eb809d | 3395 | |
79ebd55c | 3396 | /* Give up if we already have tried to compute an estimation. */ |
946e1bc7 | 3397 | if (loop->estimate_state != EST_NOT_COMPUTED) |
79ebd55c | 3398 | return; |
03fd03d5 | 3399 | |
9bdb685e | 3400 | loop->estimate_state = EST_AVAILABLE; |
03fd03d5 | 3401 | /* Force estimate compuation but leave any existing upper bound in place. */ |
9bdb685e | 3402 | loop->any_estimate = false; |
79ebd55c | 3403 | |
fbd28bc3 JJ |
3404 | /* Ensure that loop->nb_iterations is computed if possible. If it turns out |
3405 | to be constant, we avoid undefined behavior implied bounds and instead | |
3406 | diagnose those loops with -Waggressive-loop-optimizations. */ | |
3407 | number_of_latch_executions (loop); | |
3408 | ||
ca83d385 | 3409 | exits = get_loop_exit_edges (loop); |
f9bf4777 | 3410 | likely_exit = single_likely_exit (loop); |
9771b263 | 3411 | FOR_EACH_VEC_ELT (exits, i, ex) |
e9eb809d | 3412 | { |
cd0f6278 | 3413 | if (!number_of_iterations_exit (loop, ex, &niter_desc, false, false)) |
e9eb809d ZD |
3414 | continue; |
3415 | ||
3416 | niter = niter_desc.niter; | |
3417 | type = TREE_TYPE (niter); | |
946e1bc7 | 3418 | if (TREE_CODE (niter_desc.may_be_zero) != INTEGER_CST) |
e6845c23 | 3419 | niter = build3 (COND_EXPR, type, niter_desc.may_be_zero, |
ff5e9a94 | 3420 | build_int_cst (type, 0), |
e6845c23 | 3421 | niter); |
b3ce5b6e | 3422 | record_estimate (loop, niter, niter_desc.max, |
ca83d385 | 3423 | last_stmt (ex->src), |
f9bf4777 | 3424 | true, ex == likely_exit, true); |
e9eb809d | 3425 | } |
9771b263 | 3426 | exits.release (); |
b8698a0f | 3427 | |
6e616110 RB |
3428 | if (flag_aggressive_loop_optimizations) |
3429 | infer_loop_bounds_from_undefined (loop); | |
9bdb685e | 3430 | |
73ddf95b JH |
3431 | discover_iteration_bound_by_body_walk (loop); |
3432 | ||
05322355 JH |
3433 | maybe_lower_iteration_bound (loop); |
3434 | ||
9bdb685e ZD |
3435 | /* If we have a measured profile, use it to estimate the number of |
3436 | iterations. */ | |
3437 | if (loop->header->count != 0) | |
3438 | { | |
ac84e05e | 3439 | gcov_type nit = expected_loop_iterations_unbounded (loop) + 1; |
807e902e | 3440 | bound = gcov_type_to_wide_int (nit); |
9bdb685e ZD |
3441 | record_niter_bound (loop, bound, true, false); |
3442 | } | |
fbd28bc3 JJ |
3443 | |
3444 | /* If we know the exact number of iterations of this loop, try to | |
3445 | not break code with undefined behavior by not recording smaller | |
3446 | maximum number of iterations. */ | |
3447 | if (loop->nb_iterations | |
3448 | && TREE_CODE (loop->nb_iterations) == INTEGER_CST) | |
3449 | { | |
3450 | loop->any_upper_bound = true; | |
807e902e | 3451 | loop->nb_iterations_upper_bound = wi::to_widest (loop->nb_iterations); |
fbd28bc3 | 3452 | } |
e9eb809d ZD |
3453 | } |
3454 | ||
b4a9343c ZD |
3455 | /* Sets NIT to the estimated number of executions of the latch of the |
3456 | LOOP. If CONSERVATIVE is true, we must be sure that NIT is at least as | |
3457 | large as the number of iterations. If we have no reliable estimate, | |
3458 | the function returns false, otherwise returns true. */ | |
3459 | ||
3460 | bool | |
807e902e | 3461 | estimated_loop_iterations (struct loop *loop, widest_int *nit) |
b4a9343c | 3462 | { |
e3a8f1fa JH |
3463 | /* When SCEV information is available, try to update loop iterations |
3464 | estimate. Otherwise just return whatever we recorded earlier. */ | |
3465 | if (scev_initialized_p ()) | |
3466 | estimate_numbers_of_iterations_loop (loop); | |
3467 | ||
71343877 | 3468 | return (get_estimated_loop_iterations (loop, nit)); |
652c4c71 | 3469 | } |
b4a9343c | 3470 | |
1ef88893 AM |
3471 | /* Similar to estimated_loop_iterations, but returns the estimate only |
3472 | if it fits to HOST_WIDE_INT. If this is not the case, or the estimate | |
3473 | on the number of iterations of LOOP could not be derived, returns -1. */ | |
3474 | ||
3475 | HOST_WIDE_INT | |
3476 | estimated_loop_iterations_int (struct loop *loop) | |
3477 | { | |
807e902e | 3478 | widest_int nit; |
1ef88893 AM |
3479 | HOST_WIDE_INT hwi_nit; |
3480 | ||
3481 | if (!estimated_loop_iterations (loop, &nit)) | |
3482 | return -1; | |
3483 | ||
807e902e | 3484 | if (!wi::fits_shwi_p (nit)) |
1ef88893 AM |
3485 | return -1; |
3486 | hwi_nit = nit.to_shwi (); | |
3487 | ||
3488 | return hwi_nit < 0 ? -1 : hwi_nit; | |
3489 | } | |
3490 | ||
3491 | ||
652c4c71 RG |
3492 | /* Sets NIT to an upper bound for the maximum number of executions of the |
3493 | latch of the LOOP. If we have no reliable estimate, the function returns | |
3494 | false, otherwise returns true. */ | |
3495 | ||
3496 | bool | |
807e902e | 3497 | max_loop_iterations (struct loop *loop, widest_int *nit) |
652c4c71 | 3498 | { |
e3a8f1fa JH |
3499 | /* When SCEV information is available, try to update loop iterations |
3500 | estimate. Otherwise just return whatever we recorded earlier. */ | |
3501 | if (scev_initialized_p ()) | |
3502 | estimate_numbers_of_iterations_loop (loop); | |
b4a9343c | 3503 | |
71343877 | 3504 | return get_max_loop_iterations (loop, nit); |
652c4c71 RG |
3505 | } |
3506 | ||
3507 | /* Similar to max_loop_iterations, but returns the estimate only | |
3508 | if it fits to HOST_WIDE_INT. If this is not the case, or the estimate | |
3509 | on the number of iterations of LOOP could not be derived, returns -1. */ | |
3510 | ||
3511 | HOST_WIDE_INT | |
3512 | max_loop_iterations_int (struct loop *loop) | |
b4a9343c | 3513 | { |
807e902e | 3514 | widest_int nit; |
b4a9343c ZD |
3515 | HOST_WIDE_INT hwi_nit; |
3516 | ||
652c4c71 | 3517 | if (!max_loop_iterations (loop, &nit)) |
b4a9343c ZD |
3518 | return -1; |
3519 | ||
807e902e | 3520 | if (!wi::fits_shwi_p (nit)) |
b4a9343c | 3521 | return -1; |
27bcd47c | 3522 | hwi_nit = nit.to_shwi (); |
b4a9343c ZD |
3523 | |
3524 | return hwi_nit < 0 ? -1 : hwi_nit; | |
3525 | } | |
3526 | ||
652c4c71 RG |
3527 | /* Returns an estimate for the number of executions of statements |
3528 | in the LOOP. For statements before the loop exit, this exceeds | |
3529 | the number of execution of the latch by one. */ | |
3530 | ||
3531 | HOST_WIDE_INT | |
3532 | estimated_stmt_executions_int (struct loop *loop) | |
3533 | { | |
3534 | HOST_WIDE_INT nit = estimated_loop_iterations_int (loop); | |
3535 | HOST_WIDE_INT snit; | |
3536 | ||
3537 | if (nit == -1) | |
3538 | return -1; | |
3539 | ||
3540 | snit = (HOST_WIDE_INT) ((unsigned HOST_WIDE_INT) nit + 1); | |
3541 | ||
3542 | /* If the computation overflows, return -1. */ | |
3543 | return snit < 0 ? -1 : snit; | |
3544 | } | |
3545 | ||
3546 | /* Sets NIT to the estimated maximum number of executions of the latch of the | |
3547 | LOOP, plus one. If we have no reliable estimate, the function returns | |
3548 | false, otherwise returns true. */ | |
3549 | ||
3550 | bool | |
807e902e | 3551 | max_stmt_executions (struct loop *loop, widest_int *nit) |
652c4c71 | 3552 | { |
807e902e | 3553 | widest_int nit_minus_one; |
652c4c71 RG |
3554 | |
3555 | if (!max_loop_iterations (loop, nit)) | |
3556 | return false; | |
3557 | ||
3558 | nit_minus_one = *nit; | |
3559 | ||
807e902e | 3560 | *nit += 1; |
652c4c71 | 3561 | |
807e902e | 3562 | return wi::gtu_p (*nit, nit_minus_one); |
652c4c71 RG |
3563 | } |
3564 | ||
b4a9343c | 3565 | /* Sets NIT to the estimated number of executions of the latch of the |
652c4c71 RG |
3566 | LOOP, plus one. If we have no reliable estimate, the function returns |
3567 | false, otherwise returns true. */ | |
b4a9343c ZD |
3568 | |
3569 | bool | |
807e902e | 3570 | estimated_stmt_executions (struct loop *loop, widest_int *nit) |
b4a9343c | 3571 | { |
807e902e | 3572 | widest_int nit_minus_one; |
b4a9343c | 3573 | |
652c4c71 | 3574 | if (!estimated_loop_iterations (loop, nit)) |
b4a9343c ZD |
3575 | return false; |
3576 | ||
3577 | nit_minus_one = *nit; | |
3578 | ||
807e902e | 3579 | *nit += 1; |
b4a9343c | 3580 | |
807e902e | 3581 | return wi::gtu_p (*nit, nit_minus_one); |
b4a9343c ZD |
3582 | } |
3583 | ||
d73be268 | 3584 | /* Records estimates on numbers of iterations of loops. */ |
e9eb809d ZD |
3585 | |
3586 | void | |
421e6082 | 3587 | estimate_numbers_of_iterations (void) |
e9eb809d | 3588 | { |
e9eb809d ZD |
3589 | struct loop *loop; |
3590 | ||
6ac01510 ILT |
3591 | /* We don't want to issue signed overflow warnings while getting |
3592 | loop iteration estimates. */ | |
3593 | fold_defer_overflow_warnings (); | |
3594 | ||
f0bd40b1 | 3595 | FOR_EACH_LOOP (loop, 0) |
e9eb809d | 3596 | { |
421e6082 | 3597 | estimate_numbers_of_iterations_loop (loop); |
e9eb809d | 3598 | } |
6ac01510 ILT |
3599 | |
3600 | fold_undefer_and_ignore_overflow_warnings (); | |
e9eb809d ZD |
3601 | } |
3602 | ||
e9eb809d ZD |
3603 | /* Returns true if statement S1 dominates statement S2. */ |
3604 | ||
bbc8a8dc | 3605 | bool |
726a989a | 3606 | stmt_dominates_stmt_p (gimple s1, gimple s2) |
e9eb809d | 3607 | { |
726a989a | 3608 | basic_block bb1 = gimple_bb (s1), bb2 = gimple_bb (s2); |
e9eb809d ZD |
3609 | |
3610 | if (!bb1 | |
3611 | || s1 == s2) | |
3612 | return true; | |
3613 | ||
3614 | if (bb1 == bb2) | |
3615 | { | |
726a989a | 3616 | gimple_stmt_iterator bsi; |
e9eb809d | 3617 | |
25c6036a RG |
3618 | if (gimple_code (s2) == GIMPLE_PHI) |
3619 | return false; | |
3620 | ||
3621 | if (gimple_code (s1) == GIMPLE_PHI) | |
3622 | return true; | |
3623 | ||
726a989a RB |
3624 | for (bsi = gsi_start_bb (bb1); gsi_stmt (bsi) != s2; gsi_next (&bsi)) |
3625 | if (gsi_stmt (bsi) == s1) | |
e9eb809d ZD |
3626 | return true; |
3627 | ||
3628 | return false; | |
3629 | } | |
3630 | ||
3631 | return dominated_by_p (CDI_DOMINATORS, bb2, bb1); | |
3632 | } | |
3633 | ||
763f4527 | 3634 | /* Returns true when we can prove that the number of executions of |
946e1bc7 ZD |
3635 | STMT in the loop is at most NITER, according to the bound on |
3636 | the number of executions of the statement NITER_BOUND->stmt recorded in | |
870ca331 JH |
3637 | NITER_BOUND and fact that NITER_BOUND->stmt dominate STMT. |
3638 | ||
3639 | ??? This code can become quite a CPU hog - we can have many bounds, | |
3640 | and large basic block forcing stmt_dominates_stmt_p to be queried | |
3641 | many times on a large basic blocks, so the whole thing is O(n^2) | |
3642 | for scev_probably_wraps_p invocation (that can be done n times). | |
3643 | ||
3644 | It would make more sense (and give better answers) to remember BB | |
3645 | bounds computed by discover_iteration_bound_by_body_walk. */ | |
e9eb809d | 3646 | |
1e8552eb | 3647 | static bool |
726a989a | 3648 | n_of_executions_at_most (gimple stmt, |
b8698a0f | 3649 | struct nb_iter_bound *niter_bound, |
7aa20a86 | 3650 | tree niter) |
e9eb809d | 3651 | { |
807e902e | 3652 | widest_int bound = niter_bound->bound; |
6e682d7e | 3653 | tree nit_type = TREE_TYPE (niter), e; |
2f133f46 | 3654 | enum tree_code cmp; |
1e8552eb | 3655 | |
946e1bc7 ZD |
3656 | gcc_assert (TYPE_UNSIGNED (nit_type)); |
3657 | ||
3658 | /* If the bound does not even fit into NIT_TYPE, it cannot tell us that | |
3659 | the number of iterations is small. */ | |
807e902e | 3660 | if (!wi::fits_to_tree_p (bound, nit_type)) |
946e1bc7 ZD |
3661 | return false; |
3662 | ||
3663 | /* We know that NITER_BOUND->stmt is executed at most NITER_BOUND->bound + 1 | |
3664 | times. This means that: | |
b8698a0f | 3665 | |
870ca331 JH |
3666 | -- if NITER_BOUND->is_exit is true, then everything after |
3667 | it at most NITER_BOUND->bound times. | |
946e1bc7 ZD |
3668 | |
3669 | -- If NITER_BOUND->is_exit is false, then if we can prove that when STMT | |
3670 | is executed, then NITER_BOUND->stmt is executed as well in the same | |
870ca331 JH |
3671 | iteration then STMT is executed at most NITER_BOUND->bound + 1 times. |
3672 | ||
3673 | If we can determine that NITER_BOUND->stmt is always executed | |
3674 | after STMT, then STMT is executed at most NITER_BOUND->bound + 2 times. | |
3675 | We conclude that if both statements belong to the same | |
3676 | basic block and STMT is before NITER_BOUND->stmt and there are no | |
3677 | statements with side effects in between. */ | |
946e1bc7 ZD |
3678 | |
3679 | if (niter_bound->is_exit) | |
3680 | { | |
870ca331 JH |
3681 | if (stmt == niter_bound->stmt |
3682 | || !stmt_dominates_stmt_p (niter_bound->stmt, stmt)) | |
3683 | return false; | |
3684 | cmp = GE_EXPR; | |
946e1bc7 | 3685 | } |
1e8552eb | 3686 | else |
946e1bc7 | 3687 | { |
870ca331 | 3688 | if (!stmt_dominates_stmt_p (niter_bound->stmt, stmt)) |
946e1bc7 | 3689 | { |
870ca331 JH |
3690 | gimple_stmt_iterator bsi; |
3691 | if (gimple_bb (stmt) != gimple_bb (niter_bound->stmt) | |
3692 | || gimple_code (stmt) == GIMPLE_PHI | |
3693 | || gimple_code (niter_bound->stmt) == GIMPLE_PHI) | |
3694 | return false; | |
3695 | ||
3696 | /* By stmt_dominates_stmt_p we already know that STMT appears | |
3697 | before NITER_BOUND->STMT. Still need to test that the loop | |
3698 | can not be terinated by a side effect in between. */ | |
3699 | for (bsi = gsi_for_stmt (stmt); gsi_stmt (bsi) != niter_bound->stmt; | |
3700 | gsi_next (&bsi)) | |
3701 | if (gimple_has_side_effects (gsi_stmt (bsi))) | |
3702 | return false; | |
807e902e KZ |
3703 | bound += 1; |
3704 | if (bound == 0 | |
3705 | || !wi::fits_to_tree_p (bound, nit_type)) | |
946e1bc7 ZD |
3706 | return false; |
3707 | } | |
3708 | cmp = GT_EXPR; | |
3709 | } | |
1e8552eb | 3710 | |
6e682d7e | 3711 | e = fold_binary (cmp, boolean_type_node, |
807e902e | 3712 | niter, wide_int_to_tree (nit_type, bound)); |
6e682d7e | 3713 | return e && integer_nonzerop (e); |
1e8552eb SP |
3714 | } |
3715 | ||
d7f5de76 | 3716 | /* Returns true if the arithmetics in TYPE can be assumed not to wrap. */ |
e9eb809d | 3717 | |
d7f5de76 ZD |
3718 | bool |
3719 | nowrap_type_p (tree type) | |
d7770457 | 3720 | { |
eeef0e45 ILT |
3721 | if (INTEGRAL_TYPE_P (type) |
3722 | && TYPE_OVERFLOW_UNDEFINED (type)) | |
d7f5de76 | 3723 | return true; |
d7770457 | 3724 | |
d7f5de76 ZD |
3725 | if (POINTER_TYPE_P (type)) |
3726 | return true; | |
d7770457 | 3727 | |
d7770457 SP |
3728 | return false; |
3729 | } | |
3730 | ||
1e8552eb SP |
3731 | /* Return false only when the induction variable BASE + STEP * I is |
3732 | known to not overflow: i.e. when the number of iterations is small | |
3733 | enough with respect to the step and initial condition in order to | |
3734 | keep the evolution confined in TYPEs bounds. Return true when the | |
3735 | iv is known to overflow or when the property is not computable. | |
b8698a0f | 3736 | |
d7f5de76 ZD |
3737 | USE_OVERFLOW_SEMANTICS is true if this function should assume that |
3738 | the rules for overflow of the given language apply (e.g., that signed | |
3739 | arithmetics in C does not overflow). */ | |
1e8552eb SP |
3740 | |
3741 | bool | |
b8698a0f | 3742 | scev_probably_wraps_p (tree base, tree step, |
726a989a | 3743 | gimple at_stmt, struct loop *loop, |
525dc87d | 3744 | bool use_overflow_semantics) |
1e8552eb | 3745 | { |
1e8552eb SP |
3746 | tree delta, step_abs; |
3747 | tree unsigned_type, valid_niter; | |
d7f5de76 | 3748 | tree type = TREE_TYPE (step); |
870ca331 | 3749 | tree e; |
807e902e | 3750 | widest_int niter; |
870ca331 | 3751 | struct nb_iter_bound *bound; |
d7f5de76 ZD |
3752 | |
3753 | /* FIXME: We really need something like | |
3754 | http://gcc.gnu.org/ml/gcc-patches/2005-06/msg02025.html. | |
3755 | ||
3756 | We used to test for the following situation that frequently appears | |
3757 | during address arithmetics: | |
b8698a0f | 3758 | |
d7770457 SP |
3759 | D.1621_13 = (long unsigned intD.4) D.1620_12; |
3760 | D.1622_14 = D.1621_13 * 8; | |
3761 | D.1623_15 = (doubleD.29 *) D.1622_14; | |
d7770457 | 3762 | |
d7f5de76 ZD |
3763 | And derived that the sequence corresponding to D_14 |
3764 | can be proved to not wrap because it is used for computing a | |
3765 | memory access; however, this is not really the case -- for example, | |
3766 | if D_12 = (unsigned char) [254,+,1], then D_14 has values | |
3767 | 2032, 2040, 0, 8, ..., but the code is still legal. */ | |
1e8552eb | 3768 | |
18aed06a | 3769 | if (chrec_contains_undetermined (base) |
24938ce9 | 3770 | || chrec_contains_undetermined (step)) |
d7f5de76 | 3771 | return true; |
d7770457 | 3772 | |
6e682d7e | 3773 | if (integer_zerop (step)) |
d7f5de76 | 3774 | return false; |
ab02cc4e | 3775 | |
d7f5de76 ZD |
3776 | /* If we can use the fact that signed and pointer arithmetics does not |
3777 | wrap, we are done. */ | |
dc5b3407 | 3778 | if (use_overflow_semantics && nowrap_type_p (TREE_TYPE (base))) |
d7f5de76 | 3779 | return false; |
ab02cc4e | 3780 | |
24938ce9 ZD |
3781 | /* To be able to use estimates on number of iterations of the loop, |
3782 | we must have an upper bound on the absolute value of the step. */ | |
3783 | if (TREE_CODE (step) != INTEGER_CST) | |
3784 | return true; | |
3785 | ||
6ac01510 ILT |
3786 | /* Don't issue signed overflow warnings. */ |
3787 | fold_defer_overflow_warnings (); | |
3788 | ||
d7f5de76 ZD |
3789 | /* Otherwise, compute the number of iterations before we reach the |
3790 | bound of the type, and verify that the loop is exited before this | |
3791 | occurs. */ | |
3792 | unsigned_type = unsigned_type_for (type); | |
3793 | base = fold_convert (unsigned_type, base); | |
1e8552eb | 3794 | |
d7f5de76 ZD |
3795 | if (tree_int_cst_sign_bit (step)) |
3796 | { | |
3797 | tree extreme = fold_convert (unsigned_type, | |
3798 | lower_bound_in_type (type, type)); | |
3799 | delta = fold_build2 (MINUS_EXPR, unsigned_type, base, extreme); | |
3800 | step_abs = fold_build1 (NEGATE_EXPR, unsigned_type, | |
3801 | fold_convert (unsigned_type, step)); | |
e9eb809d | 3802 | } |
d7f5de76 | 3803 | else |
3eca1bd7 | 3804 | { |
d7f5de76 ZD |
3805 | tree extreme = fold_convert (unsigned_type, |
3806 | upper_bound_in_type (type, type)); | |
3807 | delta = fold_build2 (MINUS_EXPR, unsigned_type, extreme, base); | |
3808 | step_abs = fold_convert (unsigned_type, step); | |
3eca1bd7 DN |
3809 | } |
3810 | ||
1e8552eb | 3811 | valid_niter = fold_build2 (FLOOR_DIV_EXPR, unsigned_type, delta, step_abs); |
e9eb809d | 3812 | |
421e6082 | 3813 | estimate_numbers_of_iterations_loop (loop); |
870ca331 JH |
3814 | |
3815 | if (max_loop_iterations (loop, &niter) | |
807e902e | 3816 | && wi::fits_to_tree_p (niter, TREE_TYPE (valid_niter)) |
870ca331 | 3817 | && (e = fold_binary (GT_EXPR, boolean_type_node, valid_niter, |
807e902e KZ |
3818 | wide_int_to_tree (TREE_TYPE (valid_niter), |
3819 | niter))) != NULL | |
870ca331 | 3820 | && integer_nonzerop (e)) |
6ac01510 | 3821 | { |
870ca331 JH |
3822 | fold_undefer_and_ignore_overflow_warnings (); |
3823 | return false; | |
6ac01510 | 3824 | } |
870ca331 JH |
3825 | if (at_stmt) |
3826 | for (bound = loop->bounds; bound; bound = bound->next) | |
3827 | { | |
3828 | if (n_of_executions_at_most (at_stmt, bound, valid_niter)) | |
3829 | { | |
3830 | fold_undefer_and_ignore_overflow_warnings (); | |
3831 | return false; | |
3832 | } | |
3833 | } | |
6ac01510 ILT |
3834 | |
3835 | fold_undefer_and_ignore_overflow_warnings (); | |
1e8552eb SP |
3836 | |
3837 | /* At this point we still don't have a proof that the iv does not | |
3838 | overflow: give up. */ | |
3839 | return true; | |
e9eb809d ZD |
3840 | } |
3841 | ||
e9eb809d ZD |
3842 | /* Frees the information on upper bounds on numbers of iterations of LOOP. */ |
3843 | ||
c9639aae | 3844 | void |
e9eb809d ZD |
3845 | free_numbers_of_iterations_estimates_loop (struct loop *loop) |
3846 | { | |
3847 | struct nb_iter_bound *bound, *next; | |
c9639aae ZD |
3848 | |
3849 | loop->nb_iterations = NULL; | |
946e1bc7 | 3850 | loop->estimate_state = EST_NOT_COMPUTED; |
e9eb809d ZD |
3851 | for (bound = loop->bounds; bound; bound = next) |
3852 | { | |
3853 | next = bound->next; | |
9e2f83a5 | 3854 | ggc_free (bound); |
e9eb809d ZD |
3855 | } |
3856 | ||
3857 | loop->bounds = NULL; | |
3858 | } | |
3859 | ||
d73be268 | 3860 | /* Frees the information on upper bounds on numbers of iterations of loops. */ |
e9eb809d ZD |
3861 | |
3862 | void | |
d73be268 | 3863 | free_numbers_of_iterations_estimates (void) |
e9eb809d | 3864 | { |
e9eb809d ZD |
3865 | struct loop *loop; |
3866 | ||
f0bd40b1 | 3867 | FOR_EACH_LOOP (loop, 0) |
e9eb809d | 3868 | { |
42fd6772 | 3869 | free_numbers_of_iterations_estimates_loop (loop); |
e9eb809d ZD |
3870 | } |
3871 | } | |
d5ab5675 ZD |
3872 | |
3873 | /* Substitute value VAL for ssa name NAME inside expressions held | |
3874 | at LOOP. */ | |
3875 | ||
3876 | void | |
3877 | substitute_in_loop_info (struct loop *loop, tree name, tree val) | |
3878 | { | |
d5ab5675 | 3879 | loop->nb_iterations = simplify_replace_tree (loop->nb_iterations, name, val); |
d5ab5675 | 3880 | } |