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b9d73ea6 | 1 | /* Scalar evolution detector. |
2 | Copyright (C) 2003, 2004 Free Software Foundation, Inc. | |
3 | Contributed by Sebastian Pop <s.pop@laposte.net> | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 2, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING. If not, write to the Free | |
19 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
20 | 02111-1307, USA. */ | |
21 | ||
c2c3fd24 | 22 | /* |
23 | Description: | |
24 | ||
25 | This pass analyzes the evolution of scalar variables in loop | |
26 | structures. The algorithm is based on the SSA representation, | |
27 | and on the loop hierarchy tree. This algorithm is not based on | |
28 | the notion of versions of a variable, as it was the case for the | |
29 | previous implementations of the scalar evolution algorithm, but | |
30 | it assumes that each defined name is unique. | |
31 | ||
32 | The notation used in this file is called "chains of recurrences", | |
33 | and has been proposed by Eugene Zima, Robert Van Engelen, and | |
34 | others for describing induction variables in programs. For example | |
35 | "b -> {0, +, 2}_1" means that the scalar variable "b" is equal to 0 | |
36 | when entering in the loop_1 and has a step 2 in this loop, in other | |
37 | words "for (b = 0; b < N; b+=2);". Note that the coefficients of | |
38 | this chain of recurrence (or chrec [shrek]) can contain the name of | |
39 | other variables, in which case they are called parametric chrecs. | |
40 | For example, "b -> {a, +, 2}_1" means that the initial value of "b" | |
41 | is the value of "a". In most of the cases these parametric chrecs | |
42 | are fully instantiated before their use because symbolic names can | |
43 | hide some difficult cases such as self-references described later | |
44 | (see the Fibonacci example). | |
45 | ||
46 | A short sketch of the algorithm is: | |
47 | ||
48 | Given a scalar variable to be analyzed, follow the SSA edge to | |
49 | its definition: | |
50 | ||
51 | - When the definition is a MODIFY_EXPR: if the right hand side | |
52 | (RHS) of the definition cannot be statically analyzed, the answer | |
53 | of the analyzer is: "don't know". | |
54 | Otherwise, for all the variables that are not yet analyzed in the | |
55 | RHS, try to determine their evolution, and finally try to | |
56 | evaluate the operation of the RHS that gives the evolution | |
57 | function of the analyzed variable. | |
58 | ||
59 | - When the definition is a condition-phi-node: determine the | |
60 | evolution function for all the branches of the phi node, and | |
61 | finally merge these evolutions (see chrec_merge). | |
62 | ||
63 | - When the definition is a loop-phi-node: determine its initial | |
64 | condition, that is the SSA edge defined in an outer loop, and | |
65 | keep it symbolic. Then determine the SSA edges that are defined | |
66 | in the body of the loop. Follow the inner edges until ending on | |
67 | another loop-phi-node of the same analyzed loop. If the reached | |
68 | loop-phi-node is not the starting loop-phi-node, then we keep | |
69 | this definition under a symbolic form. If the reached | |
70 | loop-phi-node is the same as the starting one, then we compute a | |
71 | symbolic stride on the return path. The result is then the | |
72 | symbolic chrec {initial_condition, +, symbolic_stride}_loop. | |
73 | ||
74 | Examples: | |
75 | ||
76 | Example 1: Illustration of the basic algorithm. | |
77 | ||
78 | | a = 3 | |
79 | | loop_1 | |
80 | | b = phi (a, c) | |
81 | | c = b + 1 | |
82 | | if (c > 10) exit_loop | |
83 | | endloop | |
84 | ||
85 | Suppose that we want to know the number of iterations of the | |
86 | loop_1. The exit_loop is controlled by a COND_EXPR (c > 10). We | |
87 | ask the scalar evolution analyzer two questions: what's the | |
88 | scalar evolution (scev) of "c", and what's the scev of "10". For | |
89 | "10" the answer is "10" since it is a scalar constant. For the | |
90 | scalar variable "c", it follows the SSA edge to its definition, | |
91 | "c = b + 1", and then asks again what's the scev of "b". | |
92 | Following the SSA edge, we end on a loop-phi-node "b = phi (a, | |
93 | c)", where the initial condition is "a", and the inner loop edge | |
94 | is "c". The initial condition is kept under a symbolic form (it | |
95 | may be the case that the copy constant propagation has done its | |
96 | work and we end with the constant "3" as one of the edges of the | |
97 | loop-phi-node). The update edge is followed to the end of the | |
98 | loop, and until reaching again the starting loop-phi-node: b -> c | |
99 | -> b. At this point we have drawn a path from "b" to "b" from | |
100 | which we compute the stride in the loop: in this example it is | |
101 | "+1". The resulting scev for "b" is "b -> {a, +, 1}_1". Now | |
102 | that the scev for "b" is known, it is possible to compute the | |
103 | scev for "c", that is "c -> {a + 1, +, 1}_1". In order to | |
104 | determine the number of iterations in the loop_1, we have to | |
105 | instantiate_parameters ({a + 1, +, 1}_1), that gives after some | |
106 | more analysis the scev {4, +, 1}_1, or in other words, this is | |
107 | the function "f (x) = x + 4", where x is the iteration count of | |
108 | the loop_1. Now we have to solve the inequality "x + 4 > 10", | |
109 | and take the smallest iteration number for which the loop is | |
110 | exited: x = 7. This loop runs from x = 0 to x = 7, and in total | |
111 | there are 8 iterations. In terms of loop normalization, we have | |
112 | created a variable that is implicitly defined, "x" or just "_1", | |
113 | and all the other analyzed scalars of the loop are defined in | |
114 | function of this variable: | |
115 | ||
116 | a -> 3 | |
117 | b -> {3, +, 1}_1 | |
118 | c -> {4, +, 1}_1 | |
119 | ||
120 | or in terms of a C program: | |
121 | ||
122 | | a = 3 | |
123 | | for (x = 0; x <= 7; x++) | |
124 | | { | |
125 | | b = x + 3 | |
126 | | c = x + 4 | |
127 | | } | |
128 | ||
129 | Example 2: Illustration of the algorithm on nested loops. | |
130 | ||
131 | | loop_1 | |
132 | | a = phi (1, b) | |
133 | | c = a + 2 | |
134 | | loop_2 10 times | |
135 | | b = phi (c, d) | |
136 | | d = b + 3 | |
137 | | endloop | |
138 | | endloop | |
139 | ||
140 | For analyzing the scalar evolution of "a", the algorithm follows | |
141 | the SSA edge into the loop's body: "a -> b". "b" is an inner | |
142 | loop-phi-node, and its analysis as in Example 1, gives: | |
143 | ||
144 | b -> {c, +, 3}_2 | |
145 | d -> {c + 3, +, 3}_2 | |
146 | ||
147 | Following the SSA edge for the initial condition, we end on "c = a | |
148 | + 2", and then on the starting loop-phi-node "a". From this point, | |
149 | the loop stride is computed: back on "c = a + 2" we get a "+2" in | |
150 | the loop_1, then on the loop-phi-node "b" we compute the overall | |
151 | effect of the inner loop that is "b = c + 30", and we get a "+30" | |
152 | in the loop_1. That means that the overall stride in loop_1 is | |
153 | equal to "+32", and the result is: | |
154 | ||
155 | a -> {1, +, 32}_1 | |
156 | c -> {3, +, 32}_1 | |
157 | ||
158 | Example 3: Higher degree polynomials. | |
159 | ||
160 | | loop_1 | |
161 | | a = phi (2, b) | |
162 | | c = phi (5, d) | |
163 | | b = a + 1 | |
164 | | d = c + a | |
165 | | endloop | |
166 | ||
167 | a -> {2, +, 1}_1 | |
168 | b -> {3, +, 1}_1 | |
169 | c -> {5, +, a}_1 | |
170 | d -> {5 + a, +, a}_1 | |
171 | ||
172 | instantiate_parameters ({5, +, a}_1) -> {5, +, 2, +, 1}_1 | |
173 | instantiate_parameters ({5 + a, +, a}_1) -> {7, +, 3, +, 1}_1 | |
174 | ||
175 | Example 4: Lucas, Fibonacci, or mixers in general. | |
176 | ||
177 | | loop_1 | |
178 | | a = phi (1, b) | |
179 | | c = phi (3, d) | |
180 | | b = c | |
181 | | d = c + a | |
182 | | endloop | |
183 | ||
184 | a -> (1, c)_1 | |
185 | c -> {3, +, a}_1 | |
186 | ||
187 | The syntax "(1, c)_1" stands for a PEELED_CHREC that has the | |
188 | following semantics: during the first iteration of the loop_1, the | |
189 | variable contains the value 1, and then it contains the value "c". | |
190 | Note that this syntax is close to the syntax of the loop-phi-node: | |
191 | "a -> (1, c)_1" vs. "a = phi (1, c)". | |
192 | ||
193 | The symbolic chrec representation contains all the semantics of the | |
194 | original code. What is more difficult is to use this information. | |
195 | ||
196 | Example 5: Flip-flops, or exchangers. | |
197 | ||
198 | | loop_1 | |
199 | | a = phi (1, b) | |
200 | | c = phi (3, d) | |
201 | | b = c | |
202 | | d = a | |
203 | | endloop | |
204 | ||
205 | a -> (1, c)_1 | |
206 | c -> (3, a)_1 | |
207 | ||
208 | Based on these symbolic chrecs, it is possible to refine this | |
209 | information into the more precise PERIODIC_CHRECs: | |
210 | ||
211 | a -> |1, 3|_1 | |
212 | c -> |3, 1|_1 | |
213 | ||
214 | This transformation is not yet implemented. | |
215 | ||
216 | Further readings: | |
217 | ||
218 | You can find a more detailed description of the algorithm in: | |
219 | http://icps.u-strasbg.fr/~pop/DEA_03_Pop.pdf | |
220 | http://icps.u-strasbg.fr/~pop/DEA_03_Pop.ps.gz. But note that | |
221 | this is a preliminary report and some of the details of the | |
222 | algorithm have changed. I'm working on a research report that | |
223 | updates the description of the algorithms to reflect the design | |
224 | choices used in this implementation. | |
225 | ||
226 | A set of slides show a high level overview of the algorithm and run | |
227 | an example through the scalar evolution analyzer: | |
228 | http://cri.ensmp.fr/~pop/gcc/mar04/slides.pdf | |
229 | ||
230 | The slides that I have presented at the GCC Summit'04 are available | |
231 | at: http://cri.ensmp.fr/~pop/gcc/20040604/gccsummit-lno-spop.pdf | |
232 | */ | |
233 | ||
b9d73ea6 | 234 | #include "config.h" |
235 | #include "system.h" | |
236 | #include "coretypes.h" | |
237 | #include "tm.h" | |
238 | #include "errors.h" | |
239 | #include "ggc.h" | |
240 | #include "tree.h" | |
c2c3fd24 | 241 | |
242 | /* These RTL headers are needed for basic-block.h. */ | |
b9d73ea6 | 243 | #include "rtl.h" |
244 | #include "basic-block.h" | |
245 | #include "diagnostic.h" | |
246 | #include "tree-flow.h" | |
247 | #include "tree-dump.h" | |
248 | #include "timevar.h" | |
249 | #include "cfgloop.h" | |
250 | #include "tree-chrec.h" | |
251 | #include "tree-scalar-evolution.h" | |
c2c3fd24 | 252 | #include "tree-pass.h" |
253 | #include "flags.h" | |
254 | ||
255 | static tree analyze_scalar_evolution_1 (struct loop *, tree, tree); | |
256 | static tree resolve_mixers (struct loop *, tree); | |
257 | ||
258 | /* The cached information about a ssa name VAR, claiming that inside LOOP, | |
259 | the value of VAR can be expressed as CHREC. */ | |
260 | ||
261 | struct scev_info_str | |
262 | { | |
263 | tree var; | |
264 | tree chrec; | |
265 | }; | |
266 | ||
267 | /* Counters for the scev database. */ | |
268 | static unsigned nb_set_scev = 0; | |
269 | static unsigned nb_get_scev = 0; | |
270 | ||
271 | /* The following trees are unique elements. Thus the comparison of | |
272 | another element to these elements should be done on the pointer to | |
273 | these trees, and not on their value. */ | |
274 | ||
275 | /* The SSA_NAMEs that are not yet analyzed are qualified with NULL_TREE. */ | |
276 | tree chrec_not_analyzed_yet; | |
277 | ||
278 | /* Reserved to the cases where the analyzer has detected an | |
279 | undecidable property at compile time. */ | |
280 | tree chrec_dont_know; | |
281 | ||
282 | /* When the analyzer has detected that a property will never | |
283 | happen, then it qualifies it with chrec_known. */ | |
284 | tree chrec_known; | |
285 | ||
286 | static bitmap already_instantiated; | |
287 | ||
288 | static htab_t scalar_evolution_info; | |
289 | ||
290 | \f | |
291 | /* Constructs a new SCEV_INFO_STR structure. */ | |
292 | ||
293 | static inline struct scev_info_str * | |
294 | new_scev_info_str (tree var) | |
295 | { | |
296 | struct scev_info_str *res; | |
297 | ||
298 | res = xmalloc (sizeof (struct scev_info_str)); | |
299 | res->var = var; | |
300 | res->chrec = chrec_not_analyzed_yet; | |
301 | ||
302 | return res; | |
303 | } | |
304 | ||
305 | /* Computes a hash function for database element ELT. */ | |
306 | ||
307 | static hashval_t | |
308 | hash_scev_info (const void *elt) | |
309 | { | |
310 | return SSA_NAME_VERSION (((struct scev_info_str *) elt)->var); | |
311 | } | |
312 | ||
313 | /* Compares database elements E1 and E2. */ | |
314 | ||
315 | static int | |
316 | eq_scev_info (const void *e1, const void *e2) | |
317 | { | |
318 | const struct scev_info_str *elt1 = e1; | |
319 | const struct scev_info_str *elt2 = e2; | |
320 | ||
321 | return elt1->var == elt2->var; | |
322 | } | |
323 | ||
324 | /* Deletes database element E. */ | |
325 | ||
326 | static void | |
327 | del_scev_info (void *e) | |
328 | { | |
329 | free (e); | |
330 | } | |
331 | ||
332 | /* Get the index corresponding to VAR in the current LOOP. If | |
333 | it's the first time we ask for this VAR, then we return | |
334 | chrec_not_analysed_yet for this VAR and return its index. */ | |
335 | ||
336 | static tree * | |
337 | find_var_scev_info (tree var) | |
338 | { | |
339 | struct scev_info_str *res; | |
340 | struct scev_info_str tmp; | |
341 | PTR *slot; | |
342 | ||
343 | tmp.var = var; | |
344 | slot = htab_find_slot (scalar_evolution_info, &tmp, INSERT); | |
345 | ||
346 | if (!*slot) | |
347 | *slot = new_scev_info_str (var); | |
348 | res = *slot; | |
349 | ||
350 | return &res->chrec; | |
351 | } | |
352 | ||
353 | /* Tries to express CHREC in wider type TYPE. */ | |
354 | ||
355 | tree | |
356 | count_ev_in_wider_type (tree type, tree chrec) | |
357 | { | |
358 | tree base, step; | |
359 | struct loop *loop; | |
360 | ||
361 | if (!evolution_function_is_affine_p (chrec)) | |
362 | return fold_convert (type, chrec); | |
363 | ||
364 | base = CHREC_LEFT (chrec); | |
365 | step = CHREC_RIGHT (chrec); | |
366 | loop = current_loops->parray[CHREC_VARIABLE (chrec)]; | |
367 | ||
368 | /* TODO -- if we knew the statement at that the conversion occurs, | |
369 | we could pass it to can_count_iv_in_wider_type and get a better | |
370 | result. */ | |
371 | step = can_count_iv_in_wider_type (loop, type, base, step, NULL_TREE); | |
372 | if (!step) | |
373 | return fold_convert (type, chrec); | |
374 | base = chrec_convert (type, base); | |
375 | ||
376 | return build_polynomial_chrec (CHREC_VARIABLE (chrec), | |
377 | base, step); | |
378 | } | |
379 | ||
380 | /* Return true when CHREC contains symbolic names defined in | |
381 | LOOP_NB. */ | |
382 | ||
383 | bool | |
384 | chrec_contains_symbols_defined_in_loop (tree chrec, unsigned loop_nb) | |
385 | { | |
386 | if (chrec == NULL_TREE) | |
387 | return false; | |
388 | ||
389 | if (TREE_INVARIANT (chrec)) | |
390 | return false; | |
391 | ||
392 | if (TREE_CODE (chrec) == VAR_DECL | |
393 | || TREE_CODE (chrec) == PARM_DECL | |
394 | || TREE_CODE (chrec) == FUNCTION_DECL | |
395 | || TREE_CODE (chrec) == LABEL_DECL | |
396 | || TREE_CODE (chrec) == RESULT_DECL | |
397 | || TREE_CODE (chrec) == FIELD_DECL) | |
398 | return true; | |
399 | ||
400 | if (TREE_CODE (chrec) == SSA_NAME) | |
401 | { | |
402 | tree def = SSA_NAME_DEF_STMT (chrec); | |
403 | struct loop *def_loop = loop_containing_stmt (def); | |
404 | struct loop *loop = current_loops->parray[loop_nb]; | |
405 | ||
406 | if (def_loop == NULL) | |
407 | return false; | |
408 | ||
409 | if (loop == def_loop || flow_loop_nested_p (loop, def_loop)) | |
410 | return true; | |
411 | ||
412 | return false; | |
413 | } | |
414 | ||
415 | switch (TREE_CODE_LENGTH (TREE_CODE (chrec))) | |
416 | { | |
417 | case 3: | |
418 | if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (chrec, 2), | |
419 | loop_nb)) | |
420 | return true; | |
421 | ||
422 | case 2: | |
423 | if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (chrec, 1), | |
424 | loop_nb)) | |
425 | return true; | |
426 | ||
427 | case 1: | |
428 | if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (chrec, 0), | |
429 | loop_nb)) | |
430 | return true; | |
431 | ||
432 | default: | |
433 | return false; | |
434 | } | |
435 | } | |
436 | ||
437 | /* Return true when PHI is a loop-phi-node. */ | |
438 | ||
439 | static bool | |
440 | loop_phi_node_p (tree phi) | |
441 | { | |
442 | /* The implementation of this function is based on the following | |
443 | property: "all the loop-phi-nodes of a loop are contained in the | |
444 | loop's header basic block". */ | |
445 | ||
446 | return loop_containing_stmt (phi)->header == bb_for_stmt (phi); | |
447 | } | |
448 | ||
449 | /* Compute the scalar evolution for EVOLUTION_FN after crossing LOOP. | |
450 | In general, in the case of multivariate evolutions we want to get | |
451 | the evolution in different loops. LOOP specifies the level for | |
452 | which to get the evolution. | |
453 | ||
454 | Example: | |
455 | ||
456 | | for (j = 0; j < 100; j++) | |
457 | | { | |
458 | | for (k = 0; k < 100; k++) | |
459 | | { | |
460 | | i = k + j; - Here the value of i is a function of j, k. | |
461 | | } | |
462 | | ... = i - Here the value of i is a function of j. | |
463 | | } | |
464 | | ... = i - Here the value of i is a scalar. | |
465 | ||
466 | Example: | |
467 | ||
468 | | i_0 = ... | |
469 | | loop_1 10 times | |
470 | | i_1 = phi (i_0, i_2) | |
471 | | i_2 = i_1 + 2 | |
472 | | endloop | |
473 | ||
474 | This loop has the same effect as: | |
475 | LOOP_1 has the same effect as: | |
476 | ||
477 | | i_1 = i_0 + 20 | |
478 | ||
479 | The overall effect of the loop, "i_0 + 20" in the previous example, | |
480 | is obtained by passing in the parameters: LOOP = 1, | |
481 | EVOLUTION_FN = {i_0, +, 2}_1. | |
482 | */ | |
483 | ||
484 | static tree | |
485 | compute_overall_effect_of_inner_loop (struct loop *loop, tree evolution_fn) | |
486 | { | |
487 | bool val = false; | |
488 | ||
489 | if (evolution_fn == chrec_dont_know) | |
490 | return chrec_dont_know; | |
491 | ||
492 | else if (TREE_CODE (evolution_fn) == POLYNOMIAL_CHREC) | |
493 | { | |
494 | if (CHREC_VARIABLE (evolution_fn) >= (unsigned) loop->num) | |
495 | { | |
496 | struct loop *inner_loop = | |
497 | current_loops->parray[CHREC_VARIABLE (evolution_fn)]; | |
498 | tree nb_iter = number_of_iterations_in_loop (inner_loop); | |
499 | ||
500 | if (nb_iter == chrec_dont_know) | |
501 | return chrec_dont_know; | |
502 | else | |
503 | { | |
504 | tree res; | |
505 | ||
506 | /* Number of iterations is off by one (the ssa name we | |
507 | analyze must be defined before the exit). */ | |
508 | nb_iter = chrec_fold_minus (chrec_type (nb_iter), | |
509 | nb_iter, | |
510 | fold_convert (chrec_type (nb_iter), | |
511 | integer_one_node)); | |
512 | ||
513 | /* evolution_fn is the evolution function in LOOP. Get | |
514 | its value in the nb_iter-th iteration. */ | |
515 | res = chrec_apply (inner_loop->num, evolution_fn, nb_iter); | |
516 | ||
517 | /* Continue the computation until ending on a parent of LOOP. */ | |
518 | return compute_overall_effect_of_inner_loop (loop, res); | |
519 | } | |
520 | } | |
521 | else | |
522 | return evolution_fn; | |
523 | } | |
524 | ||
525 | /* If the evolution function is an invariant, there is nothing to do. */ | |
526 | else if (no_evolution_in_loop_p (evolution_fn, loop->num, &val) && val) | |
527 | return evolution_fn; | |
528 | ||
529 | else | |
530 | return chrec_dont_know; | |
531 | } | |
532 | ||
533 | /* Determine whether the CHREC is always positive/negative. If the expression | |
534 | cannot be statically analyzed, return false, otherwise set the answer into | |
535 | VALUE. */ | |
536 | ||
537 | bool | |
538 | chrec_is_positive (tree chrec, bool *value) | |
539 | { | |
540 | bool value0, value1; | |
541 | bool value2; | |
542 | tree end_value; | |
543 | tree nb_iter; | |
544 | ||
545 | switch (TREE_CODE (chrec)) | |
546 | { | |
547 | case POLYNOMIAL_CHREC: | |
548 | if (!chrec_is_positive (CHREC_LEFT (chrec), &value0) | |
549 | || !chrec_is_positive (CHREC_RIGHT (chrec), &value1)) | |
550 | return false; | |
551 | ||
552 | /* FIXME -- overflows. */ | |
553 | if (value0 == value1) | |
554 | { | |
555 | *value = value0; | |
556 | return true; | |
557 | } | |
558 | ||
559 | /* Otherwise the chrec is under the form: "{-197, +, 2}_1", | |
560 | and the proof consists in showing that the sign never | |
561 | changes during the execution of the loop, from 0 to | |
562 | loop->nb_iterations. */ | |
563 | if (!evolution_function_is_affine_p (chrec)) | |
564 | return false; | |
565 | ||
566 | nb_iter = number_of_iterations_in_loop | |
567 | (current_loops->parray[CHREC_VARIABLE (chrec)]); | |
568 | ||
569 | if (chrec_contains_undetermined (nb_iter)) | |
570 | return false; | |
571 | ||
572 | nb_iter = chrec_fold_minus | |
573 | (chrec_type (nb_iter), nb_iter, | |
574 | fold_convert (chrec_type (nb_iter), integer_one_node)); | |
575 | ||
576 | #if 0 | |
577 | /* TODO -- If the test is after the exit, we may decrease the number of | |
578 | iterations by one. */ | |
579 | if (after_exit) | |
580 | nb_iter = chrec_fold_minus | |
581 | (chrec_type (nb_iter), nb_iter, | |
582 | fold_convert (chrec_type (nb_iter), integer_one_node)); | |
583 | #endif | |
584 | ||
585 | end_value = chrec_apply (CHREC_VARIABLE (chrec), chrec, nb_iter); | |
586 | ||
587 | if (!chrec_is_positive (end_value, &value2)) | |
588 | return false; | |
589 | ||
590 | *value = value0; | |
591 | return value0 == value1; | |
592 | ||
593 | case INTEGER_CST: | |
594 | *value = (tree_int_cst_sgn (chrec) == 1); | |
595 | return true; | |
596 | ||
597 | default: | |
598 | return false; | |
599 | } | |
600 | } | |
601 | ||
602 | /* Associate CHREC to SCALAR. */ | |
603 | ||
604 | static void | |
605 | set_scalar_evolution (tree scalar, tree chrec) | |
606 | { | |
607 | tree *scalar_info; | |
608 | ||
609 | if (TREE_CODE (scalar) != SSA_NAME) | |
610 | return; | |
611 | ||
612 | scalar_info = find_var_scev_info (scalar); | |
613 | ||
614 | if (dump_file) | |
615 | { | |
616 | if (dump_flags & TDF_DETAILS) | |
617 | { | |
618 | fprintf (dump_file, "(set_scalar_evolution \n"); | |
619 | fprintf (dump_file, " (scalar = "); | |
620 | print_generic_expr (dump_file, scalar, 0); | |
621 | fprintf (dump_file, ")\n (scalar_evolution = "); | |
622 | print_generic_expr (dump_file, chrec, 0); | |
623 | fprintf (dump_file, "))\n"); | |
624 | } | |
625 | if (dump_flags & TDF_STATS) | |
626 | nb_set_scev++; | |
627 | } | |
628 | ||
629 | *scalar_info = chrec; | |
630 | } | |
631 | ||
632 | /* Retrieve the chrec associated to SCALAR in the LOOP. */ | |
633 | ||
634 | static tree | |
635 | get_scalar_evolution (tree scalar) | |
636 | { | |
637 | tree res; | |
638 | ||
639 | if (dump_file) | |
640 | { | |
641 | if (dump_flags & TDF_DETAILS) | |
642 | { | |
643 | fprintf (dump_file, "(get_scalar_evolution \n"); | |
644 | fprintf (dump_file, " (scalar = "); | |
645 | print_generic_expr (dump_file, scalar, 0); | |
646 | fprintf (dump_file, ")\n"); | |
647 | } | |
648 | if (dump_flags & TDF_STATS) | |
649 | nb_get_scev++; | |
650 | } | |
651 | ||
652 | switch (TREE_CODE (scalar)) | |
653 | { | |
654 | case SSA_NAME: | |
655 | res = *find_var_scev_info (scalar); | |
656 | break; | |
657 | ||
658 | case REAL_CST: | |
659 | case INTEGER_CST: | |
660 | res = scalar; | |
661 | break; | |
662 | ||
663 | default: | |
664 | res = chrec_not_analyzed_yet; | |
665 | break; | |
666 | } | |
667 | ||
668 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
669 | { | |
670 | fprintf (dump_file, " (scalar_evolution = "); | |
671 | print_generic_expr (dump_file, res, 0); | |
672 | fprintf (dump_file, "))\n"); | |
673 | } | |
674 | ||
675 | return res; | |
676 | } | |
677 | ||
678 | /* Helper function for add_to_evolution. Returns the evolution | |
679 | function for an assignment of the form "a = b + c", where "a" and | |
680 | "b" are on the strongly connected component. CHREC_BEFORE is the | |
681 | information that we already have collected up to this point. | |
682 | TO_ADD is the evolution of "c". | |
683 | ||
684 | When CHREC_BEFORE has an evolution part in LOOP_NB, add to this | |
685 | evolution the expression TO_ADD, otherwise construct an evolution | |
686 | part for this loop. */ | |
687 | ||
688 | static tree | |
689 | add_to_evolution_1 (unsigned loop_nb, | |
690 | tree chrec_before, | |
691 | tree to_add) | |
692 | { | |
693 | switch (TREE_CODE (chrec_before)) | |
694 | { | |
695 | case POLYNOMIAL_CHREC: | |
696 | if (CHREC_VARIABLE (chrec_before) <= loop_nb) | |
697 | { | |
698 | unsigned var; | |
699 | tree left, right; | |
700 | tree type = chrec_type (chrec_before); | |
701 | ||
702 | /* When there is no evolution part in this loop, build it. */ | |
703 | if (CHREC_VARIABLE (chrec_before) < loop_nb) | |
704 | { | |
705 | var = loop_nb; | |
706 | left = chrec_before; | |
707 | right = fold_convert (type, integer_zero_node); | |
708 | } | |
709 | else | |
710 | { | |
711 | var = CHREC_VARIABLE (chrec_before); | |
712 | left = CHREC_LEFT (chrec_before); | |
713 | right = CHREC_RIGHT (chrec_before); | |
714 | } | |
715 | ||
716 | return build_polynomial_chrec | |
717 | (var, left, chrec_fold_plus (type, right, to_add)); | |
718 | } | |
719 | else | |
720 | /* Search the evolution in LOOP_NB. */ | |
721 | return build_polynomial_chrec | |
722 | (CHREC_VARIABLE (chrec_before), | |
723 | add_to_evolution_1 (loop_nb, CHREC_LEFT (chrec_before), to_add), | |
724 | CHREC_RIGHT (chrec_before)); | |
725 | ||
726 | default: | |
727 | /* These nodes do not depend on a loop. */ | |
728 | if (chrec_before == chrec_dont_know) | |
729 | return chrec_dont_know; | |
730 | return build_polynomial_chrec (loop_nb, chrec_before, to_add); | |
731 | } | |
732 | } | |
733 | ||
734 | /* Add TO_ADD to the evolution part of CHREC_BEFORE in the dimension | |
735 | of LOOP_NB. | |
736 | ||
737 | Description (provided for completeness, for those who read code in | |
738 | a plane, and for my poor 62 bytes brain that would have forgotten | |
739 | all this in the next two or three months): | |
740 | ||
741 | The algorithm of translation of programs from the SSA representation | |
742 | into the chrecs syntax is based on a pattern matching. After having | |
743 | reconstructed the overall tree expression for a loop, there are only | |
744 | two cases that can arise: | |
745 | ||
746 | 1. a = loop-phi (init, a + expr) | |
747 | 2. a = loop-phi (init, expr) | |
748 | ||
749 | where EXPR is either a scalar constant with respect to the analyzed | |
750 | loop (this is a degree 0 polynomial), or an expression containing | |
751 | other loop-phi definitions (these are higher degree polynomials). | |
752 | ||
753 | Examples: | |
754 | ||
755 | 1. | |
756 | | init = ... | |
757 | | loop_1 | |
758 | | a = phi (init, a + 5) | |
759 | | endloop | |
760 | ||
761 | 2. | |
762 | | inita = ... | |
763 | | initb = ... | |
764 | | loop_1 | |
765 | | a = phi (inita, 2 * b + 3) | |
766 | | b = phi (initb, b + 1) | |
767 | | endloop | |
768 | ||
769 | For the first case, the semantics of the SSA representation is: | |
770 | ||
771 | | a (x) = init + \sum_{j = 0}^{x - 1} expr (j) | |
772 | ||
773 | that is, there is a loop index "x" that determines the scalar value | |
774 | of the variable during the loop execution. During the first | |
775 | iteration, the value is that of the initial condition INIT, while | |
776 | during the subsequent iterations, it is the sum of the initial | |
777 | condition with the sum of all the values of EXPR from the initial | |
778 | iteration to the before last considered iteration. | |
779 | ||
780 | For the second case, the semantics of the SSA program is: | |
781 | ||
782 | | a (x) = init, if x = 0; | |
783 | | expr (x - 1), otherwise. | |
784 | ||
785 | The second case corresponds to the PEELED_CHREC, whose syntax is | |
786 | close to the syntax of a loop-phi-node: | |
787 | ||
788 | | phi (init, expr) vs. (init, expr)_x | |
789 | ||
790 | The proof of the translation algorithm for the first case is a | |
791 | proof by structural induction based on the degree of EXPR. | |
792 | ||
793 | Degree 0: | |
794 | When EXPR is a constant with respect to the analyzed loop, or in | |
795 | other words when EXPR is a polynomial of degree 0, the evolution of | |
796 | the variable A in the loop is an affine function with an initial | |
797 | condition INIT, and a step EXPR. In order to show this, we start | |
798 | from the semantics of the SSA representation: | |
799 | ||
800 | f (x) = init + \sum_{j = 0}^{x - 1} expr (j) | |
801 | ||
802 | and since "expr (j)" is a constant with respect to "j", | |
803 | ||
804 | f (x) = init + x * expr | |
805 | ||
806 | Finally, based on the semantics of the pure sum chrecs, by | |
807 | identification we get the corresponding chrecs syntax: | |
808 | ||
809 | f (x) = init * \binom{x}{0} + expr * \binom{x}{1} | |
810 | f (x) -> {init, +, expr}_x | |
811 | ||
812 | Higher degree: | |
813 | Suppose that EXPR is a polynomial of degree N with respect to the | |
814 | analyzed loop_x for which we have already determined that it is | |
815 | written under the chrecs syntax: | |
816 | ||
817 | | expr (x) -> {b_0, +, b_1, +, ..., +, b_{n-1}} (x) | |
818 | ||
819 | We start from the semantics of the SSA program: | |
820 | ||
821 | | f (x) = init + \sum_{j = 0}^{x - 1} expr (j) | |
822 | | | |
823 | | f (x) = init + \sum_{j = 0}^{x - 1} | |
824 | | (b_0 * \binom{j}{0} + ... + b_{n-1} * \binom{j}{n-1}) | |
825 | | | |
826 | | f (x) = init + \sum_{j = 0}^{x - 1} | |
827 | | \sum_{k = 0}^{n - 1} (b_k * \binom{j}{k}) | |
828 | | | |
829 | | f (x) = init + \sum_{k = 0}^{n - 1} | |
830 | | (b_k * \sum_{j = 0}^{x - 1} \binom{j}{k}) | |
831 | | | |
832 | | f (x) = init + \sum_{k = 0}^{n - 1} | |
833 | | (b_k * \binom{x}{k + 1}) | |
834 | | | |
835 | | f (x) = init + b_0 * \binom{x}{1} + ... | |
836 | | + b_{n-1} * \binom{x}{n} | |
837 | | | |
838 | | f (x) = init * \binom{x}{0} + b_0 * \binom{x}{1} + ... | |
839 | | + b_{n-1} * \binom{x}{n} | |
840 | | | |
841 | ||
842 | And finally from the definition of the chrecs syntax, we identify: | |
843 | | f (x) -> {init, +, b_0, +, ..., +, b_{n-1}}_x | |
844 | ||
845 | This shows the mechanism that stands behind the add_to_evolution | |
846 | function. An important point is that the use of symbolic | |
847 | parameters avoids the need of an analysis schedule. | |
848 | ||
849 | Example: | |
850 | ||
851 | | inita = ... | |
852 | | initb = ... | |
853 | | loop_1 | |
854 | | a = phi (inita, a + 2 + b) | |
855 | | b = phi (initb, b + 1) | |
856 | | endloop | |
857 | ||
858 | When analyzing "a", the algorithm keeps "b" symbolically: | |
859 | ||
860 | | a -> {inita, +, 2 + b}_1 | |
861 | ||
862 | Then, after instantiation, the analyzer ends on the evolution: | |
863 | ||
864 | | a -> {inita, +, 2 + initb, +, 1}_1 | |
865 | ||
866 | */ | |
867 | ||
868 | static tree | |
869 | add_to_evolution (unsigned loop_nb, | |
870 | tree chrec_before, | |
871 | enum tree_code code, | |
872 | tree to_add) | |
873 | { | |
874 | tree type = chrec_type (to_add); | |
875 | tree res = NULL_TREE; | |
876 | ||
877 | if (to_add == NULL_TREE) | |
878 | return chrec_before; | |
879 | ||
880 | /* TO_ADD is either a scalar, or a parameter. TO_ADD is not | |
881 | instantiated at this point. */ | |
882 | if (TREE_CODE (to_add) == POLYNOMIAL_CHREC) | |
883 | /* This should not happen. */ | |
884 | return chrec_dont_know; | |
885 | ||
886 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
887 | { | |
888 | fprintf (dump_file, "(add_to_evolution \n"); | |
889 | fprintf (dump_file, " (loop_nb = %d)\n", loop_nb); | |
890 | fprintf (dump_file, " (chrec_before = "); | |
891 | print_generic_expr (dump_file, chrec_before, 0); | |
892 | fprintf (dump_file, ")\n (to_add = "); | |
893 | print_generic_expr (dump_file, to_add, 0); | |
894 | fprintf (dump_file, ")\n"); | |
895 | } | |
896 | ||
897 | if (code == MINUS_EXPR) | |
898 | to_add = chrec_fold_multiply (type, to_add, | |
899 | fold_convert (type, integer_minus_one_node)); | |
900 | ||
901 | res = add_to_evolution_1 (loop_nb, chrec_before, to_add); | |
902 | ||
903 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
904 | { | |
905 | fprintf (dump_file, " (res = "); | |
906 | print_generic_expr (dump_file, res, 0); | |
907 | fprintf (dump_file, "))\n"); | |
908 | } | |
909 | ||
910 | return res; | |
911 | } | |
912 | ||
913 | /* Helper function. */ | |
914 | ||
915 | static inline tree | |
916 | set_nb_iterations_in_loop (struct loop *loop, | |
917 | tree res) | |
918 | { | |
919 | res = chrec_fold_plus (chrec_type (res), res, integer_one_node); | |
920 | /* FIXME HWI: However we want to store one iteration less than the | |
921 | count of the loop in order to be compatible with the other | |
922 | nb_iter computations in loop-iv. This also allows the | |
923 | representation of nb_iters that are equal to MAX_INT. */ | |
924 | if ((TREE_CODE (res) == INTEGER_CST && TREE_INT_CST_LOW (res) == 0) | |
925 | || TREE_OVERFLOW (res)) | |
926 | res = chrec_dont_know; | |
927 | ||
928 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
929 | { | |
930 | fprintf (dump_file, " (set_nb_iterations_in_loop = "); | |
931 | print_generic_expr (dump_file, res, 0); | |
932 | fprintf (dump_file, "))\n"); | |
933 | } | |
934 | ||
935 | loop->nb_iterations = res; | |
936 | return res; | |
937 | } | |
938 | ||
939 | \f | |
940 | ||
941 | /* This section selects the loops that will be good candidates for the | |
942 | scalar evolution analysis. For the moment, greedily select all the | |
943 | loop nests we could analyze. */ | |
944 | ||
945 | /* Return true when it is possible to analyze the condition expression | |
946 | EXPR. */ | |
947 | ||
948 | static bool | |
949 | analyzable_condition (tree expr) | |
950 | { | |
951 | tree condition; | |
952 | ||
953 | if (TREE_CODE (expr) != COND_EXPR) | |
954 | return false; | |
955 | ||
956 | condition = TREE_OPERAND (expr, 0); | |
957 | ||
958 | switch (TREE_CODE (condition)) | |
959 | { | |
960 | case SSA_NAME: | |
961 | /* Volatile expressions are not analyzable. */ | |
962 | if (TREE_THIS_VOLATILE (SSA_NAME_VAR (condition))) | |
963 | return false; | |
964 | return true; | |
965 | ||
966 | case LT_EXPR: | |
967 | case LE_EXPR: | |
968 | case GT_EXPR: | |
969 | case GE_EXPR: | |
970 | case EQ_EXPR: | |
971 | case NE_EXPR: | |
972 | { | |
973 | tree opnd0, opnd1; | |
974 | ||
975 | opnd0 = TREE_OPERAND (condition, 0); | |
976 | opnd1 = TREE_OPERAND (condition, 1); | |
977 | ||
978 | if (TREE_CODE (opnd0) == SSA_NAME | |
979 | && TREE_THIS_VOLATILE (SSA_NAME_VAR (opnd0))) | |
980 | return false; | |
981 | ||
982 | if (TREE_CODE (opnd1) == SSA_NAME | |
983 | && TREE_THIS_VOLATILE (SSA_NAME_VAR (opnd1))) | |
984 | return false; | |
985 | ||
986 | return true; | |
987 | } | |
988 | ||
989 | default: | |
990 | return false; | |
991 | } | |
992 | ||
993 | return false; | |
994 | } | |
995 | ||
996 | /* For a loop with a single exit edge, return the COND_EXPR that | |
997 | guards the exit edge. If the expression is too difficult to | |
998 | analyze, then give up. */ | |
999 | ||
1000 | tree | |
1001 | get_loop_exit_condition (struct loop *loop) | |
1002 | { | |
1003 | tree res = NULL_TREE; | |
1004 | ||
1005 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1006 | fprintf (dump_file, "(get_loop_exit_condition \n "); | |
1007 | ||
1008 | if (loop->exit_edges) | |
1009 | { | |
1010 | edge exit_edge; | |
1011 | tree expr; | |
1012 | ||
1013 | exit_edge = loop->exit_edges[0]; | |
1014 | expr = last_stmt (exit_edge->src); | |
1015 | ||
1016 | if (analyzable_condition (expr)) | |
1017 | res = expr; | |
1018 | } | |
1019 | ||
1020 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1021 | { | |
1022 | print_generic_expr (dump_file, res, 0); | |
1023 | fprintf (dump_file, ")\n"); | |
1024 | } | |
1025 | ||
1026 | return res; | |
1027 | } | |
1028 | ||
1029 | /* Recursively determine and enqueue the exit conditions for a loop. */ | |
1030 | ||
1031 | static void | |
1032 | get_exit_conditions_rec (struct loop *loop, | |
1033 | varray_type *exit_conditions) | |
1034 | { | |
1035 | if (!loop) | |
1036 | return; | |
1037 | ||
1038 | /* Recurse on the inner loops, then on the next (sibling) loops. */ | |
1039 | get_exit_conditions_rec (loop->inner, exit_conditions); | |
1040 | get_exit_conditions_rec (loop->next, exit_conditions); | |
1041 | ||
1042 | flow_loop_scan (loop, LOOP_EXIT_EDGES); | |
1043 | if (loop->num_exits == 1) | |
1044 | { | |
1045 | tree loop_condition = get_loop_exit_condition (loop); | |
1046 | ||
1047 | if (loop_condition) | |
1048 | VARRAY_PUSH_TREE (*exit_conditions, loop_condition); | |
1049 | } | |
1050 | } | |
1051 | ||
1052 | /* Select the candidate loop nests for the analysis. This function | |
1053 | initializes the EXIT_CONDITIONS array. */ | |
1054 | ||
1055 | static void | |
1056 | select_loops_exit_conditions (struct loops *loops, | |
1057 | varray_type *exit_conditions) | |
1058 | { | |
1059 | struct loop *function_body = loops->parray[0]; | |
1060 | ||
1061 | get_exit_conditions_rec (function_body->inner, exit_conditions); | |
1062 | } | |
1063 | ||
1064 | \f | |
1065 | /* Depth first search algorithm. */ | |
1066 | ||
1067 | static bool follow_ssa_edge (struct loop *loop, tree, tree, tree *); | |
1068 | ||
1069 | /* Follow the ssa edge into the right hand side RHS of an assignment. | |
1070 | Return true if the strongly connected component has been found. */ | |
1071 | ||
1072 | static bool | |
1073 | follow_ssa_edge_in_rhs (struct loop *loop, | |
1074 | tree rhs, | |
1075 | tree halting_phi, | |
1076 | tree *evolution_of_loop) | |
1077 | { | |
1078 | bool res = false; | |
1079 | tree rhs0, rhs1; | |
1080 | tree type_rhs = TREE_TYPE (rhs); | |
1081 | ||
1082 | /* The RHS is one of the following cases: | |
1083 | - an SSA_NAME, | |
1084 | - an INTEGER_CST, | |
1085 | - a PLUS_EXPR, | |
1086 | - a MINUS_EXPR, | |
1087 | - other cases are not yet handled. | |
1088 | */ | |
1089 | switch (TREE_CODE (rhs)) | |
1090 | { | |
1091 | case NOP_EXPR: | |
1092 | /* This assignment is under the form "a_1 = (cast) rhs. */ | |
1093 | res = follow_ssa_edge_in_rhs (loop, TREE_OPERAND (rhs, 0), halting_phi, | |
1094 | evolution_of_loop); | |
1095 | *evolution_of_loop = chrec_convert (TREE_TYPE (rhs), *evolution_of_loop); | |
1096 | break; | |
1097 | ||
1098 | case INTEGER_CST: | |
1099 | /* This assignment is under the form "a_1 = 7". */ | |
1100 | res = false; | |
1101 | break; | |
1102 | ||
1103 | case SSA_NAME: | |
1104 | /* This assignment is under the form: "a_1 = b_2". */ | |
1105 | res = follow_ssa_edge | |
1106 | (loop, SSA_NAME_DEF_STMT (rhs), halting_phi, evolution_of_loop); | |
1107 | break; | |
1108 | ||
1109 | case PLUS_EXPR: | |
1110 | /* This case is under the form "rhs0 + rhs1". */ | |
1111 | rhs0 = TREE_OPERAND (rhs, 0); | |
1112 | rhs1 = TREE_OPERAND (rhs, 1); | |
1113 | STRIP_TYPE_NOPS (rhs0); | |
1114 | STRIP_TYPE_NOPS (rhs1); | |
1115 | ||
1116 | if (TREE_CODE (rhs0) == SSA_NAME) | |
1117 | { | |
1118 | if (TREE_CODE (rhs1) == SSA_NAME) | |
1119 | { | |
1120 | /* Match an assignment under the form: | |
1121 | "a = b + c". */ | |
1122 | res = follow_ssa_edge | |
1123 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
1124 | evolution_of_loop); | |
1125 | ||
1126 | if (res) | |
1127 | *evolution_of_loop = add_to_evolution | |
1128 | (loop->num, | |
1129 | chrec_convert (type_rhs, *evolution_of_loop), | |
1130 | PLUS_EXPR, rhs1); | |
1131 | ||
1132 | else | |
1133 | { | |
1134 | res = follow_ssa_edge | |
1135 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
1136 | evolution_of_loop); | |
1137 | ||
1138 | if (res) | |
1139 | *evolution_of_loop = add_to_evolution | |
1140 | (loop->num, | |
1141 | chrec_convert (type_rhs, *evolution_of_loop), | |
1142 | PLUS_EXPR, rhs0); | |
1143 | } | |
1144 | } | |
1145 | ||
1146 | else | |
1147 | { | |
1148 | /* Match an assignment under the form: | |
1149 | "a = b + ...". */ | |
1150 | res = follow_ssa_edge | |
1151 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
1152 | evolution_of_loop); | |
1153 | if (res) | |
1154 | *evolution_of_loop = add_to_evolution | |
1155 | (loop->num, chrec_convert (type_rhs, *evolution_of_loop), | |
1156 | PLUS_EXPR, rhs1); | |
1157 | } | |
1158 | } | |
1159 | ||
1160 | else if (TREE_CODE (rhs1) == SSA_NAME) | |
1161 | { | |
1162 | /* Match an assignment under the form: | |
1163 | "a = ... + c". */ | |
1164 | res = follow_ssa_edge | |
1165 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
1166 | evolution_of_loop); | |
1167 | if (res) | |
1168 | *evolution_of_loop = add_to_evolution | |
1169 | (loop->num, chrec_convert (type_rhs, *evolution_of_loop), | |
1170 | PLUS_EXPR, rhs0); | |
1171 | } | |
1172 | ||
1173 | else | |
1174 | /* Otherwise, match an assignment under the form: | |
1175 | "a = ... + ...". */ | |
1176 | /* And there is nothing to do. */ | |
1177 | res = false; | |
1178 | ||
1179 | break; | |
1180 | ||
1181 | case MINUS_EXPR: | |
1182 | /* This case is under the form "opnd0 = rhs0 - rhs1". */ | |
1183 | rhs0 = TREE_OPERAND (rhs, 0); | |
1184 | rhs1 = TREE_OPERAND (rhs, 1); | |
1185 | STRIP_TYPE_NOPS (rhs0); | |
1186 | STRIP_TYPE_NOPS (rhs1); | |
1187 | ||
1188 | if (TREE_CODE (rhs0) == SSA_NAME) | |
1189 | { | |
1190 | if (TREE_CODE (rhs1) == SSA_NAME) | |
1191 | { | |
1192 | /* Match an assignment under the form: | |
1193 | "a = b - c". */ | |
1194 | res = follow_ssa_edge | |
1195 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
1196 | evolution_of_loop); | |
1197 | ||
1198 | if (res) | |
1199 | *evolution_of_loop = add_to_evolution | |
1200 | (loop->num, chrec_convert (type_rhs, *evolution_of_loop), | |
1201 | MINUS_EXPR, rhs1); | |
1202 | ||
1203 | else | |
1204 | { | |
1205 | res = follow_ssa_edge | |
1206 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
1207 | evolution_of_loop); | |
1208 | ||
1209 | if (res) | |
1210 | *evolution_of_loop = add_to_evolution | |
1211 | (loop->num, | |
1212 | chrec_fold_multiply (type_rhs, | |
1213 | *evolution_of_loop, | |
1214 | fold_convert (type_rhs, | |
1215 | integer_minus_one_node)), | |
1216 | PLUS_EXPR, rhs0); | |
1217 | } | |
1218 | } | |
1219 | ||
1220 | else | |
1221 | { | |
1222 | /* Match an assignment under the form: | |
1223 | "a = b - ...". */ | |
1224 | res = follow_ssa_edge | |
1225 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
1226 | evolution_of_loop); | |
1227 | if (res) | |
1228 | *evolution_of_loop = add_to_evolution | |
1229 | (loop->num, chrec_convert (type_rhs, *evolution_of_loop), | |
1230 | MINUS_EXPR, rhs1); | |
1231 | } | |
1232 | } | |
1233 | ||
1234 | else if (TREE_CODE (rhs1) == SSA_NAME) | |
1235 | { | |
1236 | /* Match an assignment under the form: | |
1237 | "a = ... - c". */ | |
1238 | res = follow_ssa_edge | |
1239 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
1240 | evolution_of_loop); | |
1241 | if (res) | |
1242 | *evolution_of_loop = add_to_evolution | |
1243 | (loop->num, | |
1244 | chrec_fold_multiply (type_rhs, | |
1245 | *evolution_of_loop, | |
1246 | fold_convert (type_rhs, integer_minus_one_node)), | |
1247 | PLUS_EXPR, rhs0); | |
1248 | } | |
1249 | ||
1250 | else | |
1251 | /* Otherwise, match an assignment under the form: | |
1252 | "a = ... - ...". */ | |
1253 | /* And there is nothing to do. */ | |
1254 | res = false; | |
1255 | ||
1256 | break; | |
1257 | ||
1258 | case MULT_EXPR: | |
1259 | /* This case is under the form "opnd0 = rhs0 * rhs1". */ | |
1260 | rhs0 = TREE_OPERAND (rhs, 0); | |
1261 | rhs1 = TREE_OPERAND (rhs, 1); | |
1262 | STRIP_TYPE_NOPS (rhs0); | |
1263 | STRIP_TYPE_NOPS (rhs1); | |
1264 | ||
1265 | if (TREE_CODE (rhs0) == SSA_NAME) | |
1266 | { | |
1267 | if (TREE_CODE (rhs1) == SSA_NAME) | |
1268 | { | |
1269 | /* Match an assignment under the form: | |
1270 | "a = b * c". */ | |
1271 | res = follow_ssa_edge | |
1272 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
1273 | evolution_of_loop); | |
1274 | ||
1275 | if (res) | |
1276 | *evolution_of_loop = chrec_dont_know; | |
1277 | ||
1278 | else | |
1279 | { | |
1280 | res = follow_ssa_edge | |
1281 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
1282 | evolution_of_loop); | |
1283 | ||
1284 | if (res) | |
1285 | *evolution_of_loop = chrec_dont_know; | |
1286 | } | |
1287 | } | |
1288 | ||
1289 | else | |
1290 | { | |
1291 | /* Match an assignment under the form: | |
1292 | "a = b * ...". */ | |
1293 | res = follow_ssa_edge | |
1294 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
1295 | evolution_of_loop); | |
1296 | if (res) | |
1297 | *evolution_of_loop = chrec_dont_know; | |
1298 | } | |
1299 | } | |
1300 | ||
1301 | else if (TREE_CODE (rhs1) == SSA_NAME) | |
1302 | { | |
1303 | /* Match an assignment under the form: | |
1304 | "a = ... * c". */ | |
1305 | res = follow_ssa_edge | |
1306 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
1307 | evolution_of_loop); | |
1308 | if (res) | |
1309 | *evolution_of_loop = chrec_dont_know; | |
1310 | } | |
1311 | ||
1312 | else | |
1313 | /* Otherwise, match an assignment under the form: | |
1314 | "a = ... * ...". */ | |
1315 | /* And there is nothing to do. */ | |
1316 | res = false; | |
1317 | ||
1318 | break; | |
1319 | ||
1320 | default: | |
1321 | res = false; | |
1322 | break; | |
1323 | } | |
1324 | ||
1325 | return res; | |
1326 | } | |
1327 | ||
1328 | /* Checks whether the I-th argument of a PHI comes from a backedge. */ | |
1329 | ||
1330 | static bool | |
1331 | backedge_phi_arg_p (tree phi, int i) | |
1332 | { | |
1333 | edge e = PHI_ARG_EDGE (phi, i); | |
1334 | ||
1335 | /* We would in fact like to test EDGE_DFS_BACK here, but we do not care | |
1336 | about updating it anywhere, and this should work as well most of the | |
1337 | time. */ | |
1338 | if (e->flags & EDGE_IRREDUCIBLE_LOOP) | |
1339 | return true; | |
1340 | ||
1341 | return false; | |
1342 | } | |
1343 | ||
1344 | /* Helper function for one branch of the condition-phi-node. Return | |
1345 | true if the strongly connected component has been found following | |
1346 | this path. */ | |
1347 | ||
1348 | static inline bool | |
1349 | follow_ssa_edge_in_condition_phi_branch (int i, | |
1350 | struct loop *loop, | |
1351 | tree condition_phi, | |
1352 | tree halting_phi, | |
1353 | tree *evolution_of_branch, | |
1354 | tree init_cond) | |
1355 | { | |
1356 | tree branch = PHI_ARG_DEF (condition_phi, i); | |
1357 | *evolution_of_branch = chrec_dont_know; | |
1358 | ||
1359 | /* Do not follow back edges (they must belong to an irreducible loop, which | |
1360 | we really do not want to worry about). */ | |
1361 | if (backedge_phi_arg_p (condition_phi, i)) | |
1362 | return false; | |
1363 | ||
1364 | if (TREE_CODE (branch) == SSA_NAME) | |
1365 | { | |
1366 | *evolution_of_branch = init_cond; | |
1367 | return follow_ssa_edge (loop, SSA_NAME_DEF_STMT (branch), halting_phi, | |
1368 | evolution_of_branch); | |
1369 | } | |
1370 | ||
1371 | /* This case occurs when one of the condition branches sets | |
1372 | the variable to a constant: ie. a phi-node like | |
1373 | "a_2 = PHI <a_7(5), 2(6)>;". | |
1374 | ||
1375 | FIXME: This case have to be refined correctly: | |
1376 | in some cases it is possible to say something better than | |
1377 | chrec_dont_know, for example using a wrap-around notation. */ | |
1378 | return false; | |
1379 | } | |
1380 | ||
1381 | /* This function merges the branches of a condition-phi-node in a | |
1382 | loop. */ | |
1383 | ||
1384 | static bool | |
1385 | follow_ssa_edge_in_condition_phi (struct loop *loop, | |
1386 | tree condition_phi, | |
1387 | tree halting_phi, | |
1388 | tree *evolution_of_loop) | |
1389 | { | |
1390 | int i; | |
1391 | tree init = *evolution_of_loop; | |
1392 | tree evolution_of_branch; | |
1393 | ||
1394 | if (!follow_ssa_edge_in_condition_phi_branch (0, loop, condition_phi, | |
1395 | halting_phi, | |
1396 | &evolution_of_branch, | |
1397 | init)) | |
1398 | return false; | |
1399 | *evolution_of_loop = evolution_of_branch; | |
1400 | ||
1401 | for (i = 1; i < PHI_NUM_ARGS (condition_phi); i++) | |
1402 | { | |
1403 | if (!follow_ssa_edge_in_condition_phi_branch (i, loop, condition_phi, | |
1404 | halting_phi, | |
1405 | &evolution_of_branch, | |
1406 | init)) | |
1407 | return false; | |
1408 | ||
1409 | *evolution_of_loop = chrec_merge (*evolution_of_loop, | |
1410 | evolution_of_branch); | |
1411 | } | |
1412 | ||
1413 | return true; | |
1414 | } | |
1415 | ||
1416 | /* Follow an SSA edge in an inner loop. It computes the overall | |
1417 | effect of the loop, and following the symbolic initial conditions, | |
1418 | it follows the edges in the parent loop. The inner loop is | |
1419 | considered as a single statement. */ | |
1420 | ||
1421 | static bool | |
1422 | follow_ssa_edge_inner_loop_phi (struct loop *outer_loop, | |
1423 | tree loop_phi_node, | |
1424 | tree halting_phi, | |
1425 | tree *evolution_of_loop) | |
1426 | { | |
1427 | struct loop *loop = loop_containing_stmt (loop_phi_node); | |
1428 | tree ev = analyze_scalar_evolution (loop, PHI_RESULT (loop_phi_node)); | |
1429 | ||
1430 | /* Sometimes, the inner loop is too difficult to analyze, and the | |
1431 | result of the analysis is a symbolic parameter. */ | |
1432 | if (ev == PHI_RESULT (loop_phi_node)) | |
1433 | { | |
1434 | bool res = false; | |
1435 | int i; | |
1436 | ||
1437 | for (i = 0; i < PHI_NUM_ARGS (loop_phi_node); i++) | |
1438 | { | |
1439 | tree arg = PHI_ARG_DEF (loop_phi_node, i); | |
1440 | basic_block bb; | |
1441 | ||
1442 | /* Follow the edges that exit the inner loop. */ | |
1443 | bb = PHI_ARG_EDGE (loop_phi_node, i)->src; | |
1444 | if (!flow_bb_inside_loop_p (loop, bb)) | |
1445 | res = res || follow_ssa_edge_in_rhs (outer_loop, arg, halting_phi, | |
1446 | evolution_of_loop); | |
1447 | } | |
1448 | ||
1449 | /* If the path crosses this loop-phi, give up. */ | |
1450 | if (res == true) | |
1451 | *evolution_of_loop = chrec_dont_know; | |
1452 | ||
1453 | return res; | |
1454 | } | |
1455 | ||
1456 | /* Otherwise, compute the overall effect of the inner loop. */ | |
1457 | ev = compute_overall_effect_of_inner_loop (loop, ev); | |
1458 | return follow_ssa_edge_in_rhs (outer_loop, ev, halting_phi, | |
1459 | evolution_of_loop); | |
1460 | } | |
1461 | ||
1462 | /* Follow an SSA edge from a loop-phi-node to itself, constructing a | |
1463 | path that is analyzed on the return walk. */ | |
1464 | ||
1465 | static bool | |
1466 | follow_ssa_edge (struct loop *loop, | |
1467 | tree def, | |
1468 | tree halting_phi, | |
1469 | tree *evolution_of_loop) | |
1470 | { | |
1471 | struct loop *def_loop; | |
1472 | ||
1473 | if (TREE_CODE (def) == NOP_EXPR) | |
1474 | return false; | |
1475 | ||
1476 | def_loop = loop_containing_stmt (def); | |
1477 | ||
1478 | switch (TREE_CODE (def)) | |
1479 | { | |
1480 | case PHI_NODE: | |
1481 | if (!loop_phi_node_p (def)) | |
1482 | /* DEF is a condition-phi-node. Follow the branches, and | |
1483 | record their evolutions. Finally, merge the collected | |
1484 | information and set the approximation to the main | |
1485 | variable. */ | |
1486 | return follow_ssa_edge_in_condition_phi | |
1487 | (loop, def, halting_phi, evolution_of_loop); | |
1488 | ||
1489 | /* When the analyzed phi is the halting_phi, the | |
1490 | depth-first search is over: we have found a path from | |
1491 | the halting_phi to itself in the loop. */ | |
1492 | if (def == halting_phi) | |
1493 | return true; | |
1494 | ||
1495 | /* Otherwise, the evolution of the HALTING_PHI depends | |
1496 | on the evolution of another loop-phi-node, ie. the | |
1497 | evolution function is a higher degree polynomial. */ | |
1498 | if (def_loop == loop) | |
1499 | return false; | |
1500 | ||
1501 | /* Inner loop. */ | |
1502 | if (flow_loop_nested_p (loop, def_loop)) | |
1503 | return follow_ssa_edge_inner_loop_phi | |
1504 | (loop, def, halting_phi, evolution_of_loop); | |
1505 | ||
1506 | /* Outer loop. */ | |
1507 | return false; | |
1508 | ||
1509 | case MODIFY_EXPR: | |
1510 | return follow_ssa_edge_in_rhs (loop, | |
1511 | TREE_OPERAND (def, 1), | |
1512 | halting_phi, | |
1513 | evolution_of_loop); | |
1514 | ||
1515 | default: | |
1516 | /* At this level of abstraction, the program is just a set | |
1517 | of MODIFY_EXPRs and PHI_NODEs. In principle there is no | |
1518 | other node to be handled. */ | |
1519 | return false; | |
1520 | } | |
1521 | } | |
1522 | ||
1523 | \f | |
1524 | ||
1525 | /* Given a LOOP_PHI_NODE, this function determines the evolution | |
1526 | function from LOOP_PHI_NODE to LOOP_PHI_NODE in the loop. */ | |
1527 | ||
1528 | static tree | |
1529 | analyze_evolution_in_loop (tree loop_phi_node, | |
1530 | tree init_cond) | |
1531 | { | |
1532 | int i; | |
1533 | tree evolution_function = chrec_not_analyzed_yet; | |
1534 | struct loop *loop = loop_containing_stmt (loop_phi_node); | |
1535 | basic_block bb; | |
1536 | ||
1537 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1538 | { | |
1539 | fprintf (dump_file, "(analyze_evolution_in_loop \n"); | |
1540 | fprintf (dump_file, " (loop_phi_node = "); | |
1541 | print_generic_expr (dump_file, loop_phi_node, 0); | |
1542 | fprintf (dump_file, ")\n"); | |
1543 | } | |
1544 | ||
1545 | for (i = 0; i < PHI_NUM_ARGS (loop_phi_node); i++) | |
1546 | { | |
1547 | tree arg = PHI_ARG_DEF (loop_phi_node, i); | |
1548 | tree ssa_chain, ev_fn; | |
1549 | bool res; | |
1550 | ||
1551 | /* Select the edges that enter the loop body. */ | |
1552 | bb = PHI_ARG_EDGE (loop_phi_node, i)->src; | |
1553 | if (!flow_bb_inside_loop_p (loop, bb)) | |
1554 | continue; | |
1555 | ||
1556 | if (TREE_CODE (arg) == SSA_NAME) | |
1557 | { | |
1558 | ssa_chain = SSA_NAME_DEF_STMT (arg); | |
1559 | ||
1560 | /* Pass in the initial condition to the follow edge function. */ | |
1561 | ev_fn = init_cond; | |
1562 | res = follow_ssa_edge (loop, ssa_chain, loop_phi_node, &ev_fn); | |
1563 | } | |
1564 | else | |
1565 | res = false; | |
1566 | ||
1567 | /* When it is impossible to go back on the same | |
1568 | loop_phi_node by following the ssa edges, the | |
1569 | evolution is represented by a peeled chrec, ie. the | |
1570 | first iteration, EV_FN has the value INIT_COND, then | |
1571 | all the other iterations it has the value of ARG. | |
1572 | For the moment, PEELED_CHREC nodes are not built. */ | |
1573 | if (!res) | |
1574 | ev_fn = chrec_dont_know; | |
1575 | ||
1576 | /* When there are multiple back edges of the loop (which in fact never | |
1577 | happens currently, but nevertheless), merge their evolutions. */ | |
1578 | evolution_function = chrec_merge (evolution_function, ev_fn); | |
1579 | } | |
1580 | ||
1581 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1582 | { | |
1583 | fprintf (dump_file, " (evolution_function = "); | |
1584 | print_generic_expr (dump_file, evolution_function, 0); | |
1585 | fprintf (dump_file, "))\n"); | |
1586 | } | |
1587 | ||
1588 | return evolution_function; | |
1589 | } | |
1590 | ||
1591 | /* Given a loop-phi-node, return the initial conditions of the | |
1592 | variable on entry of the loop. When the CCP has propagated | |
1593 | constants into the loop-phi-node, the initial condition is | |
1594 | instantiated, otherwise the initial condition is kept symbolic. | |
1595 | This analyzer does not analyze the evolution outside the current | |
1596 | loop, and leaves this task to the on-demand tree reconstructor. */ | |
1597 | ||
1598 | static tree | |
1599 | analyze_initial_condition (tree loop_phi_node) | |
1600 | { | |
1601 | int i; | |
1602 | tree init_cond = chrec_not_analyzed_yet; | |
1603 | struct loop *loop = bb_for_stmt (loop_phi_node)->loop_father; | |
1604 | ||
1605 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1606 | { | |
1607 | fprintf (dump_file, "(analyze_initial_condition \n"); | |
1608 | fprintf (dump_file, " (loop_phi_node = \n"); | |
1609 | print_generic_expr (dump_file, loop_phi_node, 0); | |
1610 | fprintf (dump_file, ")\n"); | |
1611 | } | |
1612 | ||
1613 | for (i = 0; i < PHI_NUM_ARGS (loop_phi_node); i++) | |
1614 | { | |
1615 | tree branch = PHI_ARG_DEF (loop_phi_node, i); | |
1616 | basic_block bb = PHI_ARG_EDGE (loop_phi_node, i)->src; | |
1617 | ||
1618 | /* When the branch is oriented to the loop's body, it does | |
1619 | not contribute to the initial condition. */ | |
1620 | if (flow_bb_inside_loop_p (loop, bb)) | |
1621 | continue; | |
1622 | ||
1623 | if (init_cond == chrec_not_analyzed_yet) | |
1624 | { | |
1625 | init_cond = branch; | |
1626 | continue; | |
1627 | } | |
1628 | ||
1629 | if (TREE_CODE (branch) == SSA_NAME) | |
1630 | { | |
1631 | init_cond = chrec_dont_know; | |
1632 | break; | |
1633 | } | |
1634 | ||
1635 | init_cond = chrec_merge (init_cond, branch); | |
1636 | } | |
1637 | ||
1638 | /* Ooops -- a loop without an entry??? */ | |
1639 | if (init_cond == chrec_not_analyzed_yet) | |
1640 | init_cond = chrec_dont_know; | |
1641 | ||
1642 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1643 | { | |
1644 | fprintf (dump_file, " (init_cond = "); | |
1645 | print_generic_expr (dump_file, init_cond, 0); | |
1646 | fprintf (dump_file, "))\n"); | |
1647 | } | |
1648 | ||
1649 | return init_cond; | |
1650 | } | |
1651 | ||
1652 | /* Analyze the scalar evolution for LOOP_PHI_NODE. */ | |
1653 | ||
1654 | static tree | |
1655 | interpret_loop_phi (struct loop *loop, tree loop_phi_node) | |
1656 | { | |
1657 | tree res; | |
1658 | struct loop *phi_loop = loop_containing_stmt (loop_phi_node); | |
1659 | tree init_cond; | |
1660 | ||
1661 | if (phi_loop != loop) | |
1662 | { | |
1663 | struct loop *subloop; | |
1664 | tree evolution_fn = analyze_scalar_evolution | |
1665 | (phi_loop, PHI_RESULT (loop_phi_node)); | |
1666 | ||
1667 | /* Dive one level deeper. */ | |
1668 | subloop = superloop_at_depth (phi_loop, loop->depth + 1); | |
1669 | ||
1670 | /* Interpret the subloop. */ | |
1671 | res = compute_overall_effect_of_inner_loop (subloop, evolution_fn); | |
1672 | return res; | |
1673 | } | |
1674 | ||
1675 | /* Otherwise really interpret the loop phi. */ | |
1676 | init_cond = analyze_initial_condition (loop_phi_node); | |
1677 | res = analyze_evolution_in_loop (loop_phi_node, init_cond); | |
1678 | ||
1679 | return res; | |
1680 | } | |
1681 | ||
1682 | /* This function merges the branches of a condition-phi-node, | |
1683 | contained in the outermost loop, and whose arguments are already | |
1684 | analyzed. */ | |
1685 | ||
1686 | static tree | |
1687 | interpret_condition_phi (struct loop *loop, tree condition_phi) | |
1688 | { | |
1689 | int i; | |
1690 | tree res = chrec_not_analyzed_yet; | |
1691 | ||
1692 | for (i = 0; i < PHI_NUM_ARGS (condition_phi); i++) | |
1693 | { | |
1694 | tree branch_chrec; | |
1695 | ||
1696 | if (backedge_phi_arg_p (condition_phi, i)) | |
1697 | { | |
1698 | res = chrec_dont_know; | |
1699 | break; | |
1700 | } | |
1701 | ||
1702 | branch_chrec = analyze_scalar_evolution | |
1703 | (loop, PHI_ARG_DEF (condition_phi, i)); | |
1704 | ||
1705 | res = chrec_merge (res, branch_chrec); | |
1706 | } | |
1707 | ||
1708 | return res; | |
1709 | } | |
1710 | ||
1711 | /* Interpret the right hand side of a modify_expr OPND1. If we didn't | |
1712 | analyzed this node before, follow the definitions until ending | |
1713 | either on an analyzed modify_expr, or on a loop-phi-node. On the | |
1714 | return path, this function propagates evolutions (ala constant copy | |
1715 | propagation). OPND1 is not a GIMPLE expression because we could | |
1716 | analyze the effect of an inner loop: see interpret_loop_phi. */ | |
1717 | ||
1718 | static tree | |
1719 | interpret_rhs_modify_expr (struct loop *loop, | |
1720 | tree opnd1, tree type) | |
1721 | { | |
1722 | tree res, opnd10, opnd11, chrec10, chrec11; | |
1723 | ||
1724 | if (is_gimple_min_invariant (opnd1)) | |
1725 | return chrec_convert (type, opnd1); | |
1726 | ||
1727 | switch (TREE_CODE (opnd1)) | |
1728 | { | |
1729 | case PLUS_EXPR: | |
1730 | opnd10 = TREE_OPERAND (opnd1, 0); | |
1731 | opnd11 = TREE_OPERAND (opnd1, 1); | |
1732 | chrec10 = analyze_scalar_evolution (loop, opnd10); | |
1733 | chrec11 = analyze_scalar_evolution (loop, opnd11); | |
1734 | chrec10 = chrec_convert (type, chrec10); | |
1735 | chrec11 = chrec_convert (type, chrec11); | |
1736 | res = chrec_fold_plus (type, chrec10, chrec11); | |
1737 | break; | |
1738 | ||
1739 | case MINUS_EXPR: | |
1740 | opnd10 = TREE_OPERAND (opnd1, 0); | |
1741 | opnd11 = TREE_OPERAND (opnd1, 1); | |
1742 | chrec10 = analyze_scalar_evolution (loop, opnd10); | |
1743 | chrec11 = analyze_scalar_evolution (loop, opnd11); | |
1744 | chrec10 = chrec_convert (type, chrec10); | |
1745 | chrec11 = chrec_convert (type, chrec11); | |
1746 | res = chrec_fold_minus (type, chrec10, chrec11); | |
1747 | break; | |
1748 | ||
1749 | case NEGATE_EXPR: | |
1750 | opnd10 = TREE_OPERAND (opnd1, 0); | |
1751 | chrec10 = analyze_scalar_evolution (loop, opnd10); | |
1752 | chrec10 = chrec_convert (type, chrec10); | |
1753 | res = chrec_fold_minus (type, fold_convert (type, integer_zero_node), | |
1754 | chrec10); | |
1755 | break; | |
1756 | ||
1757 | case MULT_EXPR: | |
1758 | opnd10 = TREE_OPERAND (opnd1, 0); | |
1759 | opnd11 = TREE_OPERAND (opnd1, 1); | |
1760 | chrec10 = analyze_scalar_evolution (loop, opnd10); | |
1761 | chrec11 = analyze_scalar_evolution (loop, opnd11); | |
1762 | chrec10 = chrec_convert (type, chrec10); | |
1763 | chrec11 = chrec_convert (type, chrec11); | |
1764 | res = chrec_fold_multiply (type, chrec10, chrec11); | |
1765 | break; | |
1766 | ||
1767 | case SSA_NAME: | |
1768 | res = chrec_convert (type, analyze_scalar_evolution (loop, opnd1)); | |
1769 | break; | |
1770 | ||
1771 | case NOP_EXPR: | |
1772 | case CONVERT_EXPR: | |
1773 | opnd10 = TREE_OPERAND (opnd1, 0); | |
1774 | chrec10 = analyze_scalar_evolution (loop, opnd10); | |
1775 | res = chrec_convert (type, chrec10); | |
1776 | break; | |
1777 | ||
1778 | default: | |
1779 | res = chrec_dont_know; | |
1780 | break; | |
1781 | } | |
1782 | ||
1783 | return res; | |
1784 | } | |
1785 | ||
1786 | \f | |
1787 | ||
1788 | /* This section contains all the entry points: | |
1789 | - number_of_iterations_in_loop, | |
1790 | - analyze_scalar_evolution, | |
1791 | - instantiate_parameters. | |
1792 | */ | |
1793 | ||
1794 | /* Compute and return the evolution function in WRTO_LOOP, the nearest | |
1795 | common ancestor of DEF_LOOP and USE_LOOP. */ | |
1796 | ||
1797 | static tree | |
1798 | compute_scalar_evolution_in_loop (struct loop *wrto_loop, | |
1799 | struct loop *def_loop, | |
1800 | tree ev) | |
1801 | { | |
1802 | tree res; | |
1803 | if (def_loop == wrto_loop) | |
1804 | return ev; | |
1805 | ||
1806 | def_loop = superloop_at_depth (def_loop, wrto_loop->depth + 1); | |
1807 | res = compute_overall_effect_of_inner_loop (def_loop, ev); | |
1808 | ||
1809 | return analyze_scalar_evolution_1 (wrto_loop, res, chrec_not_analyzed_yet); | |
1810 | } | |
1811 | ||
1812 | /* Helper recursive function. */ | |
1813 | ||
1814 | static tree | |
1815 | analyze_scalar_evolution_1 (struct loop *loop, tree var, tree res) | |
1816 | { | |
1817 | tree def, type = TREE_TYPE (var); | |
1818 | basic_block bb; | |
1819 | struct loop *def_loop; | |
1820 | ||
1821 | if (loop == NULL) | |
1822 | return chrec_dont_know; | |
1823 | ||
1824 | if (TREE_CODE (var) != SSA_NAME) | |
1825 | return interpret_rhs_modify_expr (loop, var, type); | |
1826 | ||
1827 | def = SSA_NAME_DEF_STMT (var); | |
1828 | bb = bb_for_stmt (def); | |
1829 | def_loop = bb ? bb->loop_father : NULL; | |
1830 | ||
1831 | if (bb == NULL | |
1832 | || !flow_bb_inside_loop_p (loop, bb)) | |
1833 | { | |
1834 | /* Keep the symbolic form. */ | |
1835 | res = var; | |
1836 | goto set_and_end; | |
1837 | } | |
1838 | ||
1839 | if (res != chrec_not_analyzed_yet) | |
1840 | { | |
1841 | if (loop != bb->loop_father) | |
1842 | res = compute_scalar_evolution_in_loop | |
1843 | (find_common_loop (loop, bb->loop_father), bb->loop_father, res); | |
1844 | ||
1845 | goto set_and_end; | |
1846 | } | |
1847 | ||
1848 | if (loop != def_loop) | |
1849 | { | |
1850 | res = analyze_scalar_evolution_1 (def_loop, var, chrec_not_analyzed_yet); | |
1851 | res = compute_scalar_evolution_in_loop (loop, def_loop, res); | |
1852 | ||
1853 | goto set_and_end; | |
1854 | } | |
1855 | ||
1856 | switch (TREE_CODE (def)) | |
1857 | { | |
1858 | case MODIFY_EXPR: | |
1859 | res = interpret_rhs_modify_expr (loop, TREE_OPERAND (def, 1), type); | |
1860 | break; | |
1861 | ||
1862 | case PHI_NODE: | |
1863 | if (loop_phi_node_p (def)) | |
1864 | res = interpret_loop_phi (loop, def); | |
1865 | else | |
1866 | res = interpret_condition_phi (loop, def); | |
1867 | break; | |
1868 | ||
1869 | default: | |
1870 | res = chrec_dont_know; | |
1871 | break; | |
1872 | } | |
1873 | ||
1874 | set_and_end: | |
1875 | ||
1876 | /* Keep the symbolic form. */ | |
1877 | if (res == chrec_dont_know) | |
1878 | res = var; | |
1879 | ||
1880 | if (loop == def_loop) | |
1881 | set_scalar_evolution (var, res); | |
1882 | ||
1883 | return res; | |
1884 | } | |
1885 | ||
1886 | /* Entry point for the scalar evolution analyzer. | |
1887 | Analyzes and returns the scalar evolution of the ssa_name VAR. | |
1888 | LOOP_NB is the identifier number of the loop in which the variable | |
1889 | is used. | |
1890 | ||
1891 | Example of use: having a pointer VAR to a SSA_NAME node, STMT a | |
1892 | pointer to the statement that uses this variable, in order to | |
1893 | determine the evolution function of the variable, use the following | |
1894 | calls: | |
1895 | ||
1896 | unsigned loop_nb = loop_containing_stmt (stmt)->num; | |
1897 | tree chrec_with_symbols = analyze_scalar_evolution (loop_nb, var); | |
1898 | tree chrec_instantiated = instantiate_parameters | |
1899 | (loop_nb, chrec_with_symbols); | |
1900 | */ | |
1901 | ||
1902 | tree | |
1903 | analyze_scalar_evolution (struct loop *loop, tree var) | |
1904 | { | |
1905 | tree res; | |
1906 | ||
1907 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1908 | { | |
1909 | fprintf (dump_file, "(analyze_scalar_evolution \n"); | |
1910 | fprintf (dump_file, " (loop_nb = %d)\n", loop->num); | |
1911 | fprintf (dump_file, " (scalar = "); | |
1912 | print_generic_expr (dump_file, var, 0); | |
1913 | fprintf (dump_file, ")\n"); | |
1914 | } | |
1915 | ||
1916 | res = analyze_scalar_evolution_1 (loop, var, get_scalar_evolution (var)); | |
1917 | ||
1918 | if (TREE_CODE (var) == SSA_NAME && res == chrec_dont_know) | |
1919 | res = var; | |
1920 | ||
1921 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1922 | fprintf (dump_file, ")\n"); | |
1923 | ||
1924 | return res; | |
1925 | } | |
1926 | ||
1927 | /* Analyze scalar evolution of use of VERSION in USE_LOOP with respect to | |
1928 | WRTO_LOOP (which should be a superloop of both USE_LOOP and definition | |
1929 | of VERSION). */ | |
1930 | ||
1931 | static tree | |
1932 | analyze_scalar_evolution_in_loop (struct loop *wrto_loop, struct loop *use_loop, | |
1933 | tree version) | |
1934 | { | |
1935 | bool val = false; | |
1936 | tree ev = version; | |
1937 | ||
1938 | while (1) | |
1939 | { | |
1940 | ev = analyze_scalar_evolution (use_loop, ev); | |
1941 | ev = resolve_mixers (use_loop, ev); | |
1942 | ||
1943 | if (use_loop == wrto_loop) | |
1944 | return ev; | |
1945 | ||
1946 | /* If the value of the use changes in the inner loop, we cannot express | |
1947 | its value in the outer loop (we might try to return interval chrec, | |
1948 | but we do not have a user for it anyway) */ | |
1949 | if (!no_evolution_in_loop_p (ev, use_loop->num, &val) | |
1950 | || !val) | |
1951 | return chrec_dont_know; | |
1952 | ||
1953 | use_loop = use_loop->outer; | |
1954 | } | |
1955 | } | |
1956 | ||
1957 | /* Analyze all the parameters of the chrec that were left under a symbolic form, | |
1958 | with respect to LOOP. CHREC is the chrec to instantiate. If | |
1959 | ALLOW_SUPERLOOP_CHRECS is true, replacing loop invariants with | |
1960 | outer loop chrecs is done. */ | |
1961 | ||
1962 | static tree | |
1963 | instantiate_parameters_1 (struct loop *loop, tree chrec, | |
1964 | bool allow_superloop_chrecs) | |
1965 | { | |
1966 | tree res, op0, op1, op2; | |
1967 | basic_block def_bb; | |
1968 | struct loop *def_loop; | |
1969 | ||
1970 | if (chrec == NULL_TREE | |
1971 | || automatically_generated_chrec_p (chrec)) | |
1972 | return chrec; | |
1973 | ||
1974 | if (is_gimple_min_invariant (chrec)) | |
1975 | return chrec; | |
1976 | ||
1977 | switch (TREE_CODE (chrec)) | |
1978 | { | |
1979 | case SSA_NAME: | |
1980 | def_bb = bb_for_stmt (SSA_NAME_DEF_STMT (chrec)); | |
1981 | ||
1982 | /* A parameter (or loop invariant and we do not want to include | |
1983 | evolutions in outer loops), nothing to do. */ | |
1984 | if (!def_bb | |
1985 | || (!allow_superloop_chrecs | |
1986 | && !flow_bb_inside_loop_p (loop, def_bb))) | |
1987 | return chrec; | |
1988 | ||
1989 | /* Don't instantiate the SSA_NAME if it is in a mixer | |
1990 | structure. This is used for avoiding the instantiation of | |
1991 | recursively defined functions, such as: | |
1992 | ||
1993 | | a_2 -> {0, +, 1, +, a_2}_1 */ | |
1994 | ||
1995 | if (bitmap_bit_p (already_instantiated, SSA_NAME_VERSION (chrec))) | |
1996 | { | |
1997 | if (!flow_bb_inside_loop_p (loop, def_bb)) | |
1998 | { | |
1999 | /* We may keep the loop invariant in symbolic form. */ | |
2000 | return chrec; | |
2001 | } | |
2002 | else | |
2003 | { | |
2004 | /* Something with unknown behavior in LOOP. */ | |
2005 | return chrec_dont_know; | |
2006 | } | |
2007 | } | |
2008 | ||
2009 | def_loop = find_common_loop (loop, def_bb->loop_father); | |
2010 | ||
2011 | /* If the analysis yields a parametric chrec, instantiate the | |
2012 | result again. Avoid the cyclic instantiation in mixers. */ | |
2013 | bitmap_set_bit (already_instantiated, SSA_NAME_VERSION (chrec)); | |
2014 | res = analyze_scalar_evolution (def_loop, chrec); | |
2015 | res = instantiate_parameters_1 (loop, res, allow_superloop_chrecs); | |
2016 | bitmap_clear_bit (already_instantiated, SSA_NAME_VERSION (chrec)); | |
2017 | return res; | |
2018 | ||
2019 | case POLYNOMIAL_CHREC: | |
2020 | op0 = instantiate_parameters_1 (loop, CHREC_LEFT (chrec), | |
2021 | allow_superloop_chrecs); | |
2022 | op1 = instantiate_parameters_1 (loop, CHREC_RIGHT (chrec), | |
2023 | allow_superloop_chrecs); | |
2024 | return build_polynomial_chrec (CHREC_VARIABLE (chrec), op0, op1); | |
2025 | ||
2026 | case PLUS_EXPR: | |
2027 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2028 | allow_superloop_chrecs); | |
2029 | op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1), | |
2030 | allow_superloop_chrecs); | |
2031 | return chrec_fold_plus (TREE_TYPE (chrec), op0, op1); | |
2032 | ||
2033 | case MINUS_EXPR: | |
2034 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2035 | allow_superloop_chrecs); | |
2036 | op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1), | |
2037 | allow_superloop_chrecs); | |
2038 | return chrec_fold_minus (TREE_TYPE (chrec), op0, op1); | |
2039 | ||
2040 | case MULT_EXPR: | |
2041 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2042 | allow_superloop_chrecs); | |
2043 | op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1), | |
2044 | allow_superloop_chrecs); | |
2045 | return chrec_fold_multiply (TREE_TYPE (chrec), op0, op1); | |
2046 | ||
2047 | case NOP_EXPR: | |
2048 | case CONVERT_EXPR: | |
2049 | case NON_LVALUE_EXPR: | |
2050 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2051 | allow_superloop_chrecs); | |
2052 | if (op0 == chrec_dont_know) | |
2053 | return chrec_dont_know; | |
2054 | ||
2055 | return chrec_convert (TREE_TYPE (chrec), op0); | |
2056 | ||
2057 | case SCEV_NOT_KNOWN: | |
2058 | return chrec_dont_know; | |
2059 | ||
2060 | case SCEV_KNOWN: | |
2061 | return chrec_known; | |
2062 | ||
2063 | default: | |
2064 | break; | |
2065 | } | |
2066 | ||
2067 | switch (TREE_CODE_LENGTH (TREE_CODE (chrec))) | |
2068 | { | |
2069 | case 3: | |
2070 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2071 | allow_superloop_chrecs); | |
2072 | op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1), | |
2073 | allow_superloop_chrecs); | |
2074 | op2 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 2), | |
2075 | allow_superloop_chrecs); | |
2076 | if (op0 == chrec_dont_know | |
2077 | || op1 == chrec_dont_know | |
2078 | || op2 == chrec_dont_know) | |
2079 | return chrec_dont_know; | |
2080 | return fold (build (TREE_CODE (chrec), | |
2081 | TREE_TYPE (chrec), op0, op1, op2)); | |
2082 | ||
2083 | case 2: | |
2084 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2085 | allow_superloop_chrecs); | |
2086 | op1 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 1), | |
2087 | allow_superloop_chrecs); | |
2088 | if (op0 == chrec_dont_know | |
2089 | || op1 == chrec_dont_know) | |
2090 | return chrec_dont_know; | |
2091 | return fold (build (TREE_CODE (chrec), TREE_TYPE (chrec), op0, op1)); | |
2092 | ||
2093 | case 1: | |
2094 | op0 = instantiate_parameters_1 (loop, TREE_OPERAND (chrec, 0), | |
2095 | allow_superloop_chrecs); | |
2096 | if (op0 == chrec_dont_know) | |
2097 | return chrec_dont_know; | |
2098 | return fold (build1 (TREE_CODE (chrec), TREE_TYPE (chrec), op0)); | |
2099 | ||
2100 | case 0: | |
2101 | return chrec; | |
2102 | ||
2103 | default: | |
2104 | break; | |
2105 | } | |
2106 | ||
2107 | /* Too complicated to handle. */ | |
2108 | return chrec_dont_know; | |
2109 | } | |
b9d73ea6 | 2110 | |
2111 | /* Analyze all the parameters of the chrec that were left under a | |
2112 | symbolic form. LOOP is the loop in which symbolic names have to | |
2113 | be analyzed and instantiated. */ | |
2114 | ||
2115 | tree | |
c2c3fd24 | 2116 | instantiate_parameters (struct loop *loop, |
b9d73ea6 | 2117 | tree chrec) |
2118 | { | |
c2c3fd24 | 2119 | tree res; |
2120 | ||
2121 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2122 | { | |
2123 | fprintf (dump_file, "(instantiate_parameters \n"); | |
2124 | fprintf (dump_file, " (loop_nb = %d)\n", loop->num); | |
2125 | fprintf (dump_file, " (chrec = "); | |
2126 | print_generic_expr (dump_file, chrec, 0); | |
2127 | fprintf (dump_file, ")\n"); | |
2128 | } | |
2129 | ||
2130 | res = instantiate_parameters_1 (loop, chrec, true); | |
2131 | ||
2132 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2133 | { | |
2134 | fprintf (dump_file, " (res = "); | |
2135 | print_generic_expr (dump_file, res, 0); | |
2136 | fprintf (dump_file, "))\n"); | |
2137 | } | |
2138 | ||
2139 | return res; | |
2140 | } | |
2141 | ||
2142 | /* Similar to instantiate_parameters, but does not introduce the | |
2143 | evolutions in outer loops for LOOP invariants in CHREC. */ | |
2144 | ||
2145 | static tree | |
2146 | resolve_mixers (struct loop *loop, tree chrec) | |
2147 | { | |
2148 | return instantiate_parameters_1 (loop, chrec, false); | |
2149 | } | |
2150 | ||
2151 | /* Entry point for the analysis of the number of iterations pass. | |
2152 | This function tries to safely approximate the number of iterations | |
2153 | the loop will run. When this property is not decidable at compile | |
2154 | time, the result is chrec_dont_know. Otherwise the result is | |
2155 | a scalar or a symbolic parameter. | |
2156 | ||
2157 | Example of analysis: suppose that the loop has an exit condition: | |
2158 | ||
2159 | "if (b > 49) goto end_loop;" | |
2160 | ||
2161 | and that in a previous analysis we have determined that the | |
2162 | variable 'b' has an evolution function: | |
2163 | ||
2164 | "EF = {23, +, 5}_2". | |
2165 | ||
2166 | When we evaluate the function at the point 5, i.e. the value of the | |
2167 | variable 'b' after 5 iterations in the loop, we have EF (5) = 48, | |
2168 | and EF (6) = 53. In this case the value of 'b' on exit is '53' and | |
2169 | the loop body has been executed 6 times. */ | |
2170 | ||
2171 | tree | |
2172 | number_of_iterations_in_loop (struct loop *loop) | |
2173 | { | |
2174 | tree res, type; | |
2175 | edge exit; | |
2176 | struct tree_niter_desc niter_desc; | |
2177 | ||
2178 | /* Determine whether the number_of_iterations_in_loop has already | |
2179 | been computed. */ | |
2180 | res = loop->nb_iterations; | |
2181 | if (res) | |
2182 | return res; | |
2183 | res = chrec_dont_know; | |
2184 | ||
2185 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2186 | fprintf (dump_file, "(number_of_iterations_in_loop\n"); | |
2187 | ||
2188 | if (!loop->exit_edges) | |
2189 | goto end; | |
2190 | exit = loop->exit_edges[0]; | |
2191 | ||
2192 | if (!number_of_iterations_exit (loop, exit, &niter_desc)) | |
2193 | goto end; | |
2194 | ||
2195 | type = TREE_TYPE (niter_desc.niter); | |
2196 | if (integer_nonzerop (niter_desc.may_be_zero)) | |
2197 | res = fold_convert (type, integer_zero_node); | |
2198 | else if (integer_zerop (niter_desc.may_be_zero)) | |
2199 | res = niter_desc.niter; | |
2200 | else | |
2201 | res = chrec_dont_know; | |
2202 | ||
2203 | end: | |
2204 | return set_nb_iterations_in_loop (loop, res); | |
2205 | } | |
2206 | ||
2207 | /* One of the drivers for testing the scalar evolutions analysis. | |
2208 | This function computes the number of iterations for all the loops | |
2209 | from the EXIT_CONDITIONS array. */ | |
2210 | ||
2211 | static void | |
2212 | number_of_iterations_for_all_loops (varray_type exit_conditions) | |
2213 | { | |
2214 | unsigned int i; | |
2215 | unsigned nb_chrec_dont_know_loops = 0; | |
2216 | unsigned nb_static_loops = 0; | |
2217 | ||
2218 | for (i = 0; i < VARRAY_ACTIVE_SIZE (exit_conditions); i++) | |
2219 | { | |
2220 | tree res = number_of_iterations_in_loop | |
2221 | (loop_containing_stmt (VARRAY_TREE (exit_conditions, i))); | |
2222 | if (chrec_contains_undetermined (res)) | |
2223 | nb_chrec_dont_know_loops++; | |
2224 | else | |
2225 | nb_static_loops++; | |
2226 | } | |
2227 | ||
2228 | if (dump_file) | |
2229 | { | |
2230 | fprintf (dump_file, "\n(\n"); | |
2231 | fprintf (dump_file, "-----------------------------------------\n"); | |
2232 | fprintf (dump_file, "%d\tnb_chrec_dont_know_loops\n", nb_chrec_dont_know_loops); | |
2233 | fprintf (dump_file, "%d\tnb_static_loops\n", nb_static_loops); | |
2234 | fprintf (dump_file, "%d\tnb_total_loops\n", current_loops->num); | |
2235 | fprintf (dump_file, "-----------------------------------------\n"); | |
2236 | fprintf (dump_file, ")\n\n"); | |
2237 | ||
2238 | print_loop_ir (dump_file); | |
2239 | } | |
2240 | } | |
2241 | ||
2242 | \f | |
2243 | ||
2244 | /* Counters for the stats. */ | |
2245 | ||
2246 | struct chrec_stats | |
2247 | { | |
2248 | unsigned nb_chrecs; | |
2249 | unsigned nb_affine; | |
2250 | unsigned nb_affine_multivar; | |
2251 | unsigned nb_higher_poly; | |
2252 | unsigned nb_chrec_dont_know; | |
2253 | unsigned nb_undetermined; | |
2254 | }; | |
2255 | ||
2256 | /* Reset the counters. */ | |
2257 | ||
2258 | static inline void | |
2259 | reset_chrecs_counters (struct chrec_stats *stats) | |
2260 | { | |
2261 | stats->nb_chrecs = 0; | |
2262 | stats->nb_affine = 0; | |
2263 | stats->nb_affine_multivar = 0; | |
2264 | stats->nb_higher_poly = 0; | |
2265 | stats->nb_chrec_dont_know = 0; | |
2266 | stats->nb_undetermined = 0; | |
2267 | } | |
2268 | ||
2269 | /* Dump the contents of a CHREC_STATS structure. */ | |
2270 | ||
2271 | static void | |
2272 | dump_chrecs_stats (FILE *file, struct chrec_stats *stats) | |
2273 | { | |
2274 | fprintf (file, "\n(\n"); | |
2275 | fprintf (file, "-----------------------------------------\n"); | |
2276 | fprintf (file, "%d\taffine univariate chrecs\n", stats->nb_affine); | |
2277 | fprintf (file, "%d\taffine multivariate chrecs\n", stats->nb_affine_multivar); | |
2278 | fprintf (file, "%d\tdegree greater than 2 polynomials\n", | |
2279 | stats->nb_higher_poly); | |
2280 | fprintf (file, "%d\tchrec_dont_know chrecs\n", stats->nb_chrec_dont_know); | |
2281 | fprintf (file, "-----------------------------------------\n"); | |
2282 | fprintf (file, "%d\ttotal chrecs\n", stats->nb_chrecs); | |
2283 | fprintf (file, "%d\twith undetermined coefficients\n", | |
2284 | stats->nb_undetermined); | |
2285 | fprintf (file, "-----------------------------------------\n"); | |
2286 | fprintf (file, "%d\tchrecs in the scev database\n", | |
2287 | (int) htab_elements (scalar_evolution_info)); | |
2288 | fprintf (file, "%d\tsets in the scev database\n", nb_set_scev); | |
2289 | fprintf (file, "%d\tgets in the scev database\n", nb_get_scev); | |
2290 | fprintf (file, "-----------------------------------------\n"); | |
2291 | fprintf (file, ")\n\n"); | |
2292 | } | |
2293 | ||
2294 | /* Gather statistics about CHREC. */ | |
2295 | ||
2296 | static void | |
2297 | gather_chrec_stats (tree chrec, struct chrec_stats *stats) | |
2298 | { | |
2299 | if (dump_file && (dump_flags & TDF_STATS)) | |
2300 | { | |
2301 | fprintf (dump_file, "(classify_chrec "); | |
2302 | print_generic_expr (dump_file, chrec, 0); | |
2303 | fprintf (dump_file, "\n"); | |
2304 | } | |
2305 | ||
2306 | stats->nb_chrecs++; | |
2307 | ||
2308 | if (chrec == NULL_TREE) | |
2309 | { | |
2310 | stats->nb_undetermined++; | |
2311 | return; | |
2312 | } | |
2313 | ||
2314 | switch (TREE_CODE (chrec)) | |
2315 | { | |
2316 | case POLYNOMIAL_CHREC: | |
2317 | if (evolution_function_is_affine_p (chrec)) | |
2318 | { | |
2319 | if (dump_file && (dump_flags & TDF_STATS)) | |
2320 | fprintf (dump_file, " affine_univariate\n"); | |
2321 | stats->nb_affine++; | |
2322 | } | |
2323 | else if (evolution_function_is_affine_multivariate_p (chrec)) | |
2324 | { | |
2325 | if (dump_file && (dump_flags & TDF_STATS)) | |
2326 | fprintf (dump_file, " affine_multivariate\n"); | |
2327 | stats->nb_affine_multivar++; | |
2328 | } | |
2329 | else | |
2330 | { | |
2331 | if (dump_file && (dump_flags & TDF_STATS)) | |
2332 | fprintf (dump_file, " higher_degree_polynomial\n"); | |
2333 | stats->nb_higher_poly++; | |
2334 | } | |
2335 | ||
2336 | break; | |
2337 | ||
2338 | default: | |
2339 | break; | |
2340 | } | |
2341 | ||
2342 | if (chrec_contains_undetermined (chrec)) | |
2343 | { | |
2344 | if (dump_file && (dump_flags & TDF_STATS)) | |
2345 | fprintf (dump_file, " undetermined\n"); | |
2346 | stats->nb_undetermined++; | |
2347 | } | |
2348 | ||
2349 | if (dump_file && (dump_flags & TDF_STATS)) | |
2350 | fprintf (dump_file, ")\n"); | |
2351 | } | |
2352 | ||
2353 | /* One of the drivers for testing the scalar evolutions analysis. | |
2354 | This function analyzes the scalar evolution of all the scalars | |
2355 | defined as loop phi nodes in one of the loops from the | |
2356 | EXIT_CONDITIONS array. | |
2357 | ||
2358 | TODO Optimization: A loop is in canonical form if it contains only | |
2359 | a single scalar loop phi node. All the other scalars that have an | |
2360 | evolution in the loop are rewritten in function of this single | |
2361 | index. This allows the parallelization of the loop. */ | |
2362 | ||
2363 | static void | |
2364 | analyze_scalar_evolution_for_all_loop_phi_nodes (varray_type exit_conditions) | |
2365 | { | |
2366 | unsigned int i; | |
2367 | struct chrec_stats stats; | |
2368 | ||
2369 | reset_chrecs_counters (&stats); | |
2370 | ||
2371 | for (i = 0; i < VARRAY_ACTIVE_SIZE (exit_conditions); i++) | |
2372 | { | |
2373 | struct loop *loop; | |
2374 | basic_block bb; | |
2375 | tree phi, chrec; | |
2376 | ||
2377 | loop = loop_containing_stmt (VARRAY_TREE (exit_conditions, i)); | |
2378 | bb = loop->header; | |
2379 | ||
2380 | for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi)) | |
2381 | if (is_gimple_reg (PHI_RESULT (phi))) | |
2382 | { | |
2383 | chrec = instantiate_parameters | |
2384 | (loop, | |
2385 | analyze_scalar_evolution (loop, PHI_RESULT (phi))); | |
2386 | ||
2387 | if (dump_file && (dump_flags & TDF_STATS)) | |
2388 | gather_chrec_stats (chrec, &stats); | |
2389 | } | |
2390 | } | |
2391 | ||
2392 | if (dump_file && (dump_flags & TDF_STATS)) | |
2393 | dump_chrecs_stats (dump_file, &stats); | |
2394 | } | |
2395 | ||
2396 | /* Callback for htab_traverse, gathers information on chrecs in the | |
2397 | hashtable. */ | |
2398 | ||
2399 | static int | |
2400 | gather_stats_on_scev_database_1 (void **slot, void *stats) | |
2401 | { | |
2402 | struct scev_info_str *entry = *slot; | |
2403 | ||
2404 | gather_chrec_stats (entry->chrec, stats); | |
2405 | ||
2406 | return 1; | |
2407 | } | |
2408 | ||
2409 | /* Classify the chrecs of the whole database. */ | |
2410 | ||
2411 | void | |
2412 | gather_stats_on_scev_database (void) | |
2413 | { | |
2414 | struct chrec_stats stats; | |
2415 | ||
2416 | if (!dump_file) | |
2417 | return; | |
2418 | ||
2419 | reset_chrecs_counters (&stats); | |
2420 | ||
2421 | htab_traverse (scalar_evolution_info, gather_stats_on_scev_database_1, | |
2422 | &stats); | |
2423 | ||
2424 | dump_chrecs_stats (dump_file, &stats); | |
2425 | } | |
2426 | ||
2427 | \f | |
2428 | ||
2429 | /* Initializer. */ | |
2430 | ||
2431 | static void | |
2432 | initialize_scalar_evolutions_analyzer (void) | |
2433 | { | |
2434 | /* The elements below are unique. */ | |
2435 | if (chrec_dont_know == NULL_TREE) | |
2436 | { | |
2437 | chrec_not_analyzed_yet = NULL_TREE; | |
2438 | chrec_dont_know = make_node (SCEV_NOT_KNOWN); | |
2439 | chrec_known = make_node (SCEV_KNOWN); | |
2440 | TREE_TYPE (chrec_dont_know) = NULL_TREE; | |
2441 | TREE_TYPE (chrec_known) = NULL_TREE; | |
2442 | } | |
2443 | } | |
2444 | ||
2445 | /* Initialize the analysis of scalar evolutions for LOOPS. */ | |
2446 | ||
2447 | void | |
2448 | scev_initialize (struct loops *loops) | |
2449 | { | |
2450 | unsigned i; | |
2451 | current_loops = loops; | |
2452 | ||
2453 | scalar_evolution_info = htab_create (100, hash_scev_info, | |
2454 | eq_scev_info, del_scev_info); | |
2455 | already_instantiated = BITMAP_XMALLOC (); | |
2456 | ||
2457 | initialize_scalar_evolutions_analyzer (); | |
2458 | ||
2459 | for (i = 1; i < loops->num; i++) | |
2460 | if (loops->parray[i]) | |
2461 | { | |
2462 | flow_loop_scan (loops->parray[i], LOOP_EXIT_EDGES); | |
2463 | loops->parray[i]->nb_iterations = NULL_TREE; | |
2464 | } | |
2465 | } | |
2466 | ||
2467 | /* Cleans up the information cached by the scalar evolutions analysis. */ | |
2468 | ||
2469 | void | |
2470 | scev_reset (void) | |
2471 | { | |
2472 | unsigned i; | |
2473 | struct loop *loop; | |
2474 | ||
2475 | if (!scalar_evolution_info || !current_loops) | |
2476 | return; | |
2477 | ||
2478 | htab_empty (scalar_evolution_info); | |
2479 | for (i = 1; i < current_loops->num; i++) | |
2480 | { | |
2481 | loop = current_loops->parray[i]; | |
2482 | if (loop) | |
2483 | loop->nb_iterations = NULL_TREE; | |
2484 | } | |
b9d73ea6 | 2485 | } |
2486 | ||
2487 | /* Checks whether OP behaves as a simple affine iv of LOOP in STMT and returns | |
2488 | its BASE and STEP if possible. */ | |
2489 | ||
2490 | bool | |
c2c3fd24 | 2491 | simple_iv (struct loop *loop, tree stmt, tree op, tree *base, tree *step) |
b9d73ea6 | 2492 | { |
c2c3fd24 | 2493 | basic_block bb = bb_for_stmt (stmt); |
2494 | tree type, ev; | |
2495 | ||
2496 | *base = NULL_TREE; | |
2497 | *step = NULL_TREE; | |
2498 | ||
2499 | type = TREE_TYPE (op); | |
2500 | if (TREE_CODE (type) != INTEGER_TYPE | |
2501 | && TREE_CODE (type) != POINTER_TYPE) | |
2502 | return false; | |
2503 | ||
2504 | ev = analyze_scalar_evolution_in_loop (loop, bb->loop_father, op); | |
2505 | if (chrec_contains_undetermined (ev)) | |
2506 | return false; | |
2507 | ||
2508 | if (tree_does_not_contain_chrecs (ev) | |
2509 | && !chrec_contains_symbols_defined_in_loop (ev, loop->num)) | |
2510 | { | |
2511 | *base = ev; | |
2512 | return true; | |
2513 | } | |
2514 | ||
2515 | if (TREE_CODE (ev) != POLYNOMIAL_CHREC | |
2516 | || CHREC_VARIABLE (ev) != (unsigned) loop->num) | |
2517 | return false; | |
2518 | ||
2519 | *step = CHREC_RIGHT (ev); | |
2520 | if (TREE_CODE (*step) != INTEGER_CST) | |
2521 | return false; | |
2522 | *base = CHREC_LEFT (ev); | |
2523 | if (tree_contains_chrecs (*base) | |
2524 | || chrec_contains_symbols_defined_in_loop (*base, loop->num)) | |
2525 | return false; | |
2526 | ||
2527 | return true; | |
2528 | } | |
2529 | ||
2530 | /* Runs the analysis of scalar evolutions. */ | |
2531 | ||
2532 | void | |
2533 | scev_analysis (void) | |
2534 | { | |
2535 | varray_type exit_conditions; | |
2536 | ||
2537 | VARRAY_GENERIC_PTR_INIT (exit_conditions, 37, "exit_conditions"); | |
2538 | select_loops_exit_conditions (current_loops, &exit_conditions); | |
2539 | ||
2540 | if (dump_file && (dump_flags & TDF_STATS)) | |
2541 | analyze_scalar_evolution_for_all_loop_phi_nodes (exit_conditions); | |
2542 | ||
2543 | number_of_iterations_for_all_loops (exit_conditions); | |
2544 | VARRAY_CLEAR (exit_conditions); | |
b9d73ea6 | 2545 | } |
c2c3fd24 | 2546 | |
2547 | /* Finalize the scalar evolution analysis. */ | |
2548 | ||
2549 | void | |
2550 | scev_finalize (void) | |
2551 | { | |
2552 | htab_delete (scalar_evolution_info); | |
2553 | BITMAP_XFREE (already_instantiated); | |
2554 | } | |
2555 |