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e9eb809d | 1 | /* Scalar evolution detector. |
fa10beec RW |
2 | Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Free Software |
3 | Foundation, Inc. | |
e9eb809d ZD |
4 | Contributed by Sebastian Pop <s.pop@laposte.net> |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify it under | |
9 | the terms of the GNU General Public License as published by the Free | |
9dcd6f09 | 10 | Software Foundation; either version 3, or (at your option) any later |
e9eb809d ZD |
11 | version. |
12 | ||
13 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
14 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
16 | for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
9dcd6f09 NC |
19 | along with GCC; see the file COPYING3. If not see |
20 | <http://www.gnu.org/licenses/>. */ | |
e9eb809d | 21 | |
9baba81b SP |
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 | ||
726a989a | 51 | - When the definition is a GIMPLE_ASSIGN: if the right hand side |
9baba81b SP |
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 | |
3f227a8c | 105 | instantiate_parameters (loop_1, {a + 1, +, 1}_1), that gives after some |
9baba81b SP |
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 | ||
3f227a8c | 129 | Example 2a: Illustration of the algorithm on nested loops. |
9baba81b SP |
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 | |
3f227a8c JS |
157 | |
158 | Example 2b: Multivariate chains of recurrences. | |
159 | ||
160 | | loop_1 | |
161 | | k = phi (0, k + 1) | |
162 | | loop_2 4 times | |
163 | | j = phi (0, j + 1) | |
164 | | loop_3 4 times | |
165 | | i = phi (0, i + 1) | |
166 | | A[j + k] = ... | |
167 | | endloop | |
168 | | endloop | |
169 | | endloop | |
170 | ||
171 | Analyzing the access function of array A with | |
172 | instantiate_parameters (loop_1, "j + k"), we obtain the | |
173 | instantiation and the analysis of the scalar variables "j" and "k" | |
174 | in loop_1. This leads to the scalar evolution {4, +, 1}_1: the end | |
175 | value of loop_2 for "j" is 4, and the evolution of "k" in loop_1 is | |
176 | {0, +, 1}_1. To obtain the evolution function in loop_3 and | |
177 | instantiate the scalar variables up to loop_1, one has to use: | |
a213b219 SP |
178 | instantiate_scev (block_before_loop (loop_1), loop_3, "j + k"). |
179 | The result of this call is {{0, +, 1}_1, +, 1}_2. | |
3f227a8c | 180 | |
9baba81b SP |
181 | Example 3: Higher degree polynomials. |
182 | ||
183 | | loop_1 | |
184 | | a = phi (2, b) | |
185 | | c = phi (5, d) | |
186 | | b = a + 1 | |
187 | | d = c + a | |
188 | | endloop | |
189 | ||
190 | a -> {2, +, 1}_1 | |
191 | b -> {3, +, 1}_1 | |
192 | c -> {5, +, a}_1 | |
193 | d -> {5 + a, +, a}_1 | |
194 | ||
3f227a8c JS |
195 | instantiate_parameters (loop_1, {5, +, a}_1) -> {5, +, 2, +, 1}_1 |
196 | instantiate_parameters (loop_1, {5 + a, +, a}_1) -> {7, +, 3, +, 1}_1 | |
9baba81b SP |
197 | |
198 | Example 4: Lucas, Fibonacci, or mixers in general. | |
199 | ||
200 | | loop_1 | |
201 | | a = phi (1, b) | |
202 | | c = phi (3, d) | |
203 | | b = c | |
204 | | d = c + a | |
205 | | endloop | |
206 | ||
207 | a -> (1, c)_1 | |
208 | c -> {3, +, a}_1 | |
209 | ||
210 | The syntax "(1, c)_1" stands for a PEELED_CHREC that has the | |
211 | following semantics: during the first iteration of the loop_1, the | |
212 | variable contains the value 1, and then it contains the value "c". | |
213 | Note that this syntax is close to the syntax of the loop-phi-node: | |
214 | "a -> (1, c)_1" vs. "a = phi (1, c)". | |
215 | ||
216 | The symbolic chrec representation contains all the semantics of the | |
217 | original code. What is more difficult is to use this information. | |
218 | ||
219 | Example 5: Flip-flops, or exchangers. | |
220 | ||
221 | | loop_1 | |
222 | | a = phi (1, b) | |
223 | | c = phi (3, d) | |
224 | | b = c | |
225 | | d = a | |
226 | | endloop | |
227 | ||
228 | a -> (1, c)_1 | |
229 | c -> (3, a)_1 | |
230 | ||
231 | Based on these symbolic chrecs, it is possible to refine this | |
232 | information into the more precise PERIODIC_CHRECs: | |
233 | ||
234 | a -> |1, 3|_1 | |
235 | c -> |3, 1|_1 | |
236 | ||
237 | This transformation is not yet implemented. | |
238 | ||
239 | Further readings: | |
240 | ||
241 | You can find a more detailed description of the algorithm in: | |
242 | http://icps.u-strasbg.fr/~pop/DEA_03_Pop.pdf | |
243 | http://icps.u-strasbg.fr/~pop/DEA_03_Pop.ps.gz. But note that | |
244 | this is a preliminary report and some of the details of the | |
245 | algorithm have changed. I'm working on a research report that | |
246 | updates the description of the algorithms to reflect the design | |
247 | choices used in this implementation. | |
248 | ||
249 | A set of slides show a high level overview of the algorithm and run | |
250 | an example through the scalar evolution analyzer: | |
251 | http://cri.ensmp.fr/~pop/gcc/mar04/slides.pdf | |
252 | ||
253 | The slides that I have presented at the GCC Summit'04 are available | |
254 | at: http://cri.ensmp.fr/~pop/gcc/20040604/gccsummit-lno-spop.pdf | |
255 | */ | |
256 | ||
e9eb809d ZD |
257 | #include "config.h" |
258 | #include "system.h" | |
259 | #include "coretypes.h" | |
260 | #include "tm.h" | |
e9eb809d ZD |
261 | #include "ggc.h" |
262 | #include "tree.h" | |
9d2b0e12 | 263 | #include "real.h" |
9baba81b SP |
264 | |
265 | /* These RTL headers are needed for basic-block.h. */ | |
e9eb809d ZD |
266 | #include "rtl.h" |
267 | #include "basic-block.h" | |
268 | #include "diagnostic.h" | |
269 | #include "tree-flow.h" | |
270 | #include "tree-dump.h" | |
271 | #include "timevar.h" | |
272 | #include "cfgloop.h" | |
273 | #include "tree-chrec.h" | |
274 | #include "tree-scalar-evolution.h" | |
9baba81b SP |
275 | #include "tree-pass.h" |
276 | #include "flags.h" | |
c59dabbe | 277 | #include "params.h" |
9baba81b SP |
278 | |
279 | static tree analyze_scalar_evolution_1 (struct loop *, tree, tree); | |
9baba81b | 280 | |
a213b219 SP |
281 | /* The cached information about an SSA name VAR, claiming that below |
282 | basic block INSTANTIATED_BELOW, the value of VAR can be expressed | |
283 | as CHREC. */ | |
9baba81b | 284 | |
9e2f83a5 | 285 | struct scev_info_str GTY(()) |
9baba81b | 286 | { |
a213b219 | 287 | basic_block instantiated_below; |
9baba81b SP |
288 | tree var; |
289 | tree chrec; | |
290 | }; | |
291 | ||
292 | /* Counters for the scev database. */ | |
293 | static unsigned nb_set_scev = 0; | |
294 | static unsigned nb_get_scev = 0; | |
295 | ||
296 | /* The following trees are unique elements. Thus the comparison of | |
297 | another element to these elements should be done on the pointer to | |
298 | these trees, and not on their value. */ | |
299 | ||
300 | /* The SSA_NAMEs that are not yet analyzed are qualified with NULL_TREE. */ | |
301 | tree chrec_not_analyzed_yet; | |
302 | ||
303 | /* Reserved to the cases where the analyzer has detected an | |
304 | undecidable property at compile time. */ | |
305 | tree chrec_dont_know; | |
306 | ||
307 | /* When the analyzer has detected that a property will never | |
308 | happen, then it qualifies it with chrec_known. */ | |
309 | tree chrec_known; | |
310 | ||
9e2f83a5 | 311 | static GTY ((param_is (struct scev_info_str))) htab_t scalar_evolution_info; |
9baba81b SP |
312 | |
313 | \f | |
a213b219 | 314 | /* Constructs a new SCEV_INFO_STR structure for VAR and INSTANTIATED_BELOW. */ |
9baba81b SP |
315 | |
316 | static inline struct scev_info_str * | |
a213b219 | 317 | new_scev_info_str (basic_block instantiated_below, tree var) |
9baba81b SP |
318 | { |
319 | struct scev_info_str *res; | |
320 | ||
9e2f83a5 | 321 | res = GGC_NEW (struct scev_info_str); |
9baba81b SP |
322 | res->var = var; |
323 | res->chrec = chrec_not_analyzed_yet; | |
a213b219 SP |
324 | res->instantiated_below = instantiated_below; |
325 | ||
9baba81b SP |
326 | return res; |
327 | } | |
328 | ||
329 | /* Computes a hash function for database element ELT. */ | |
330 | ||
331 | static hashval_t | |
332 | hash_scev_info (const void *elt) | |
333 | { | |
741ac903 | 334 | return SSA_NAME_VERSION (((const struct scev_info_str *) elt)->var); |
9baba81b SP |
335 | } |
336 | ||
337 | /* Compares database elements E1 and E2. */ | |
338 | ||
339 | static int | |
340 | eq_scev_info (const void *e1, const void *e2) | |
341 | { | |
cceb1885 GDR |
342 | const struct scev_info_str *elt1 = (const struct scev_info_str *) e1; |
343 | const struct scev_info_str *elt2 = (const struct scev_info_str *) e2; | |
9baba81b | 344 | |
a213b219 SP |
345 | return (elt1->var == elt2->var |
346 | && elt1->instantiated_below == elt2->instantiated_below); | |
9baba81b SP |
347 | } |
348 | ||
349 | /* Deletes database element E. */ | |
350 | ||
351 | static void | |
352 | del_scev_info (void *e) | |
353 | { | |
9e2f83a5 | 354 | ggc_free (e); |
9baba81b SP |
355 | } |
356 | ||
a213b219 SP |
357 | /* Get the scalar evolution of VAR for INSTANTIATED_BELOW basic block. |
358 | A first query on VAR returns chrec_not_analyzed_yet. */ | |
9baba81b SP |
359 | |
360 | static tree * | |
a213b219 | 361 | find_var_scev_info (basic_block instantiated_below, tree var) |
9baba81b SP |
362 | { |
363 | struct scev_info_str *res; | |
364 | struct scev_info_str tmp; | |
365 | PTR *slot; | |
366 | ||
367 | tmp.var = var; | |
a213b219 | 368 | tmp.instantiated_below = instantiated_below; |
9baba81b SP |
369 | slot = htab_find_slot (scalar_evolution_info, &tmp, INSERT); |
370 | ||
371 | if (!*slot) | |
a213b219 | 372 | *slot = new_scev_info_str (instantiated_below, var); |
cceb1885 | 373 | res = (struct scev_info_str *) *slot; |
9baba81b SP |
374 | |
375 | return &res->chrec; | |
376 | } | |
377 | ||
9baba81b SP |
378 | /* Return true when CHREC contains symbolic names defined in |
379 | LOOP_NB. */ | |
380 | ||
381 | bool | |
ed7a4b4b | 382 | chrec_contains_symbols_defined_in_loop (const_tree chrec, unsigned loop_nb) |
9baba81b | 383 | { |
5039610b SL |
384 | int i, n; |
385 | ||
9baba81b SP |
386 | if (chrec == NULL_TREE) |
387 | return false; | |
388 | ||
ad6003f2 | 389 | if (is_gimple_min_invariant (chrec)) |
9baba81b SP |
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 | { | |
726a989a | 402 | gimple def = SSA_NAME_DEF_STMT (chrec); |
9baba81b | 403 | struct loop *def_loop = loop_containing_stmt (def); |
42fd6772 | 404 | struct loop *loop = get_loop (loop_nb); |
9baba81b SP |
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 | ||
5039610b SL |
415 | n = TREE_OPERAND_LENGTH (chrec); |
416 | for (i = 0; i < n; i++) | |
417 | if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (chrec, i), | |
418 | loop_nb)) | |
419 | return true; | |
420 | return false; | |
9baba81b SP |
421 | } |
422 | ||
423 | /* Return true when PHI is a loop-phi-node. */ | |
424 | ||
425 | static bool | |
726a989a | 426 | loop_phi_node_p (gimple phi) |
9baba81b SP |
427 | { |
428 | /* The implementation of this function is based on the following | |
429 | property: "all the loop-phi-nodes of a loop are contained in the | |
430 | loop's header basic block". */ | |
431 | ||
726a989a | 432 | return loop_containing_stmt (phi)->header == gimple_bb (phi); |
9baba81b SP |
433 | } |
434 | ||
435 | /* Compute the scalar evolution for EVOLUTION_FN after crossing LOOP. | |
436 | In general, in the case of multivariate evolutions we want to get | |
437 | the evolution in different loops. LOOP specifies the level for | |
438 | which to get the evolution. | |
439 | ||
440 | Example: | |
441 | ||
442 | | for (j = 0; j < 100; j++) | |
443 | | { | |
444 | | for (k = 0; k < 100; k++) | |
445 | | { | |
446 | | i = k + j; - Here the value of i is a function of j, k. | |
447 | | } | |
448 | | ... = i - Here the value of i is a function of j. | |
449 | | } | |
450 | | ... = i - Here the value of i is a scalar. | |
451 | ||
452 | Example: | |
453 | ||
454 | | i_0 = ... | |
455 | | loop_1 10 times | |
456 | | i_1 = phi (i_0, i_2) | |
457 | | i_2 = i_1 + 2 | |
458 | | endloop | |
459 | ||
460 | This loop has the same effect as: | |
461 | LOOP_1 has the same effect as: | |
462 | ||
463 | | i_1 = i_0 + 20 | |
464 | ||
465 | The overall effect of the loop, "i_0 + 20" in the previous example, | |
466 | is obtained by passing in the parameters: LOOP = 1, | |
467 | EVOLUTION_FN = {i_0, +, 2}_1. | |
468 | */ | |
469 | ||
470 | static tree | |
471 | compute_overall_effect_of_inner_loop (struct loop *loop, tree evolution_fn) | |
472 | { | |
473 | bool val = false; | |
474 | ||
475 | if (evolution_fn == chrec_dont_know) | |
476 | return chrec_dont_know; | |
477 | ||
478 | else if (TREE_CODE (evolution_fn) == POLYNOMIAL_CHREC) | |
479 | { | |
677cc14d ZD |
480 | struct loop *inner_loop = get_chrec_loop (evolution_fn); |
481 | ||
482 | if (inner_loop == loop | |
483 | || flow_loop_nested_p (loop, inner_loop)) | |
9baba81b | 484 | { |
a14865db | 485 | tree nb_iter = number_of_latch_executions (inner_loop); |
9baba81b SP |
486 | |
487 | if (nb_iter == chrec_dont_know) | |
488 | return chrec_dont_know; | |
489 | else | |
490 | { | |
491 | tree res; | |
492 | ||
9baba81b SP |
493 | /* evolution_fn is the evolution function in LOOP. Get |
494 | its value in the nb_iter-th iteration. */ | |
495 | res = chrec_apply (inner_loop->num, evolution_fn, nb_iter); | |
496 | ||
8c27b7d4 | 497 | /* Continue the computation until ending on a parent of LOOP. */ |
9baba81b SP |
498 | return compute_overall_effect_of_inner_loop (loop, res); |
499 | } | |
500 | } | |
501 | else | |
502 | return evolution_fn; | |
503 | } | |
504 | ||
505 | /* If the evolution function is an invariant, there is nothing to do. */ | |
506 | else if (no_evolution_in_loop_p (evolution_fn, loop->num, &val) && val) | |
507 | return evolution_fn; | |
508 | ||
509 | else | |
510 | return chrec_dont_know; | |
511 | } | |
512 | ||
513 | /* Determine whether the CHREC is always positive/negative. If the expression | |
514 | cannot be statically analyzed, return false, otherwise set the answer into | |
515 | VALUE. */ | |
516 | ||
517 | bool | |
518 | chrec_is_positive (tree chrec, bool *value) | |
519 | { | |
16a2acea | 520 | bool value0, value1, value2; |
a14865db | 521 | tree end_value, nb_iter; |
9baba81b SP |
522 | |
523 | switch (TREE_CODE (chrec)) | |
524 | { | |
525 | case POLYNOMIAL_CHREC: | |
526 | if (!chrec_is_positive (CHREC_LEFT (chrec), &value0) | |
527 | || !chrec_is_positive (CHREC_RIGHT (chrec), &value1)) | |
528 | return false; | |
529 | ||
530 | /* FIXME -- overflows. */ | |
531 | if (value0 == value1) | |
532 | { | |
533 | *value = value0; | |
534 | return true; | |
535 | } | |
536 | ||
537 | /* Otherwise the chrec is under the form: "{-197, +, 2}_1", | |
538 | and the proof consists in showing that the sign never | |
539 | changes during the execution of the loop, from 0 to | |
540 | loop->nb_iterations. */ | |
541 | if (!evolution_function_is_affine_p (chrec)) | |
542 | return false; | |
543 | ||
a14865db | 544 | nb_iter = number_of_latch_executions (get_chrec_loop (chrec)); |
9baba81b SP |
545 | if (chrec_contains_undetermined (nb_iter)) |
546 | return false; | |
547 | ||
9baba81b SP |
548 | #if 0 |
549 | /* TODO -- If the test is after the exit, we may decrease the number of | |
550 | iterations by one. */ | |
551 | if (after_exit) | |
16a2acea | 552 | nb_iter = chrec_fold_minus (type, nb_iter, build_int_cst (type, 1)); |
9baba81b SP |
553 | #endif |
554 | ||
555 | end_value = chrec_apply (CHREC_VARIABLE (chrec), chrec, nb_iter); | |
556 | ||
557 | if (!chrec_is_positive (end_value, &value2)) | |
558 | return false; | |
559 | ||
560 | *value = value0; | |
561 | return value0 == value1; | |
562 | ||
563 | case INTEGER_CST: | |
564 | *value = (tree_int_cst_sgn (chrec) == 1); | |
565 | return true; | |
566 | ||
567 | default: | |
568 | return false; | |
569 | } | |
570 | } | |
571 | ||
572 | /* Associate CHREC to SCALAR. */ | |
573 | ||
574 | static void | |
a213b219 | 575 | set_scalar_evolution (basic_block instantiated_below, tree scalar, tree chrec) |
9baba81b SP |
576 | { |
577 | tree *scalar_info; | |
578 | ||
579 | if (TREE_CODE (scalar) != SSA_NAME) | |
580 | return; | |
581 | ||
a213b219 | 582 | scalar_info = find_var_scev_info (instantiated_below, scalar); |
9baba81b SP |
583 | |
584 | if (dump_file) | |
585 | { | |
586 | if (dump_flags & TDF_DETAILS) | |
587 | { | |
588 | fprintf (dump_file, "(set_scalar_evolution \n"); | |
a213b219 SP |
589 | fprintf (dump_file, " instantiated_below = %d \n", |
590 | instantiated_below->index); | |
9baba81b SP |
591 | fprintf (dump_file, " (scalar = "); |
592 | print_generic_expr (dump_file, scalar, 0); | |
593 | fprintf (dump_file, ")\n (scalar_evolution = "); | |
594 | print_generic_expr (dump_file, chrec, 0); | |
595 | fprintf (dump_file, "))\n"); | |
596 | } | |
597 | if (dump_flags & TDF_STATS) | |
598 | nb_set_scev++; | |
599 | } | |
600 | ||
601 | *scalar_info = chrec; | |
602 | } | |
603 | ||
a213b219 SP |
604 | /* Retrieve the chrec associated to SCALAR instantiated below |
605 | INSTANTIATED_BELOW block. */ | |
9baba81b SP |
606 | |
607 | static tree | |
a213b219 | 608 | get_scalar_evolution (basic_block instantiated_below, tree scalar) |
9baba81b SP |
609 | { |
610 | tree res; | |
611 | ||
612 | if (dump_file) | |
613 | { | |
614 | if (dump_flags & TDF_DETAILS) | |
615 | { | |
616 | fprintf (dump_file, "(get_scalar_evolution \n"); | |
617 | fprintf (dump_file, " (scalar = "); | |
618 | print_generic_expr (dump_file, scalar, 0); | |
619 | fprintf (dump_file, ")\n"); | |
620 | } | |
621 | if (dump_flags & TDF_STATS) | |
622 | nb_get_scev++; | |
623 | } | |
624 | ||
625 | switch (TREE_CODE (scalar)) | |
626 | { | |
627 | case SSA_NAME: | |
a213b219 | 628 | res = *find_var_scev_info (instantiated_below, scalar); |
9baba81b SP |
629 | break; |
630 | ||
631 | case REAL_CST: | |
325217ed | 632 | case FIXED_CST: |
9baba81b SP |
633 | case INTEGER_CST: |
634 | res = scalar; | |
635 | break; | |
636 | ||
637 | default: | |
638 | res = chrec_not_analyzed_yet; | |
639 | break; | |
640 | } | |
641 | ||
642 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
643 | { | |
644 | fprintf (dump_file, " (scalar_evolution = "); | |
645 | print_generic_expr (dump_file, res, 0); | |
646 | fprintf (dump_file, "))\n"); | |
647 | } | |
648 | ||
649 | return res; | |
650 | } | |
651 | ||
652 | /* Helper function for add_to_evolution. Returns the evolution | |
653 | function for an assignment of the form "a = b + c", where "a" and | |
654 | "b" are on the strongly connected component. CHREC_BEFORE is the | |
655 | information that we already have collected up to this point. | |
656 | TO_ADD is the evolution of "c". | |
657 | ||
658 | When CHREC_BEFORE has an evolution part in LOOP_NB, add to this | |
659 | evolution the expression TO_ADD, otherwise construct an evolution | |
660 | part for this loop. */ | |
661 | ||
662 | static tree | |
e2157b49 | 663 | add_to_evolution_1 (unsigned loop_nb, tree chrec_before, tree to_add, |
726a989a | 664 | gimple at_stmt) |
9baba81b | 665 | { |
e2157b49 | 666 | tree type, left, right; |
677cc14d | 667 | struct loop *loop = get_loop (loop_nb), *chloop; |
e2157b49 | 668 | |
9baba81b SP |
669 | switch (TREE_CODE (chrec_before)) |
670 | { | |
671 | case POLYNOMIAL_CHREC: | |
677cc14d ZD |
672 | chloop = get_chrec_loop (chrec_before); |
673 | if (chloop == loop | |
674 | || flow_loop_nested_p (chloop, loop)) | |
9baba81b SP |
675 | { |
676 | unsigned var; | |
e2157b49 SP |
677 | |
678 | type = chrec_type (chrec_before); | |
9baba81b SP |
679 | |
680 | /* When there is no evolution part in this loop, build it. */ | |
677cc14d | 681 | if (chloop != loop) |
9baba81b SP |
682 | { |
683 | var = loop_nb; | |
684 | left = chrec_before; | |
7e0923cd SP |
685 | right = SCALAR_FLOAT_TYPE_P (type) |
686 | ? build_real (type, dconst0) | |
687 | : build_int_cst (type, 0); | |
9baba81b SP |
688 | } |
689 | else | |
690 | { | |
691 | var = CHREC_VARIABLE (chrec_before); | |
692 | left = CHREC_LEFT (chrec_before); | |
693 | right = CHREC_RIGHT (chrec_before); | |
694 | } | |
695 | ||
e2157b49 | 696 | to_add = chrec_convert (type, to_add, at_stmt); |
5be014d5 AP |
697 | right = chrec_convert_rhs (type, right, at_stmt); |
698 | right = chrec_fold_plus (chrec_type (right), right, to_add); | |
e2157b49 | 699 | return build_polynomial_chrec (var, left, right); |
9baba81b SP |
700 | } |
701 | else | |
e2157b49 | 702 | { |
677cc14d ZD |
703 | gcc_assert (flow_loop_nested_p (loop, chloop)); |
704 | ||
e2157b49 SP |
705 | /* Search the evolution in LOOP_NB. */ |
706 | left = add_to_evolution_1 (loop_nb, CHREC_LEFT (chrec_before), | |
707 | to_add, at_stmt); | |
708 | right = CHREC_RIGHT (chrec_before); | |
5be014d5 | 709 | right = chrec_convert_rhs (chrec_type (left), right, at_stmt); |
e2157b49 SP |
710 | return build_polynomial_chrec (CHREC_VARIABLE (chrec_before), |
711 | left, right); | |
712 | } | |
9baba81b SP |
713 | |
714 | default: | |
715 | /* These nodes do not depend on a loop. */ | |
716 | if (chrec_before == chrec_dont_know) | |
717 | return chrec_dont_know; | |
e2157b49 SP |
718 | |
719 | left = chrec_before; | |
5be014d5 | 720 | right = chrec_convert_rhs (chrec_type (left), to_add, at_stmt); |
e2157b49 | 721 | return build_polynomial_chrec (loop_nb, left, right); |
9baba81b SP |
722 | } |
723 | } | |
724 | ||
725 | /* Add TO_ADD to the evolution part of CHREC_BEFORE in the dimension | |
726 | of LOOP_NB. | |
727 | ||
728 | Description (provided for completeness, for those who read code in | |
729 | a plane, and for my poor 62 bytes brain that would have forgotten | |
730 | all this in the next two or three months): | |
731 | ||
732 | The algorithm of translation of programs from the SSA representation | |
733 | into the chrecs syntax is based on a pattern matching. After having | |
734 | reconstructed the overall tree expression for a loop, there are only | |
735 | two cases that can arise: | |
736 | ||
737 | 1. a = loop-phi (init, a + expr) | |
738 | 2. a = loop-phi (init, expr) | |
739 | ||
740 | where EXPR is either a scalar constant with respect to the analyzed | |
741 | loop (this is a degree 0 polynomial), or an expression containing | |
742 | other loop-phi definitions (these are higher degree polynomials). | |
743 | ||
744 | Examples: | |
745 | ||
746 | 1. | |
747 | | init = ... | |
748 | | loop_1 | |
749 | | a = phi (init, a + 5) | |
750 | | endloop | |
751 | ||
752 | 2. | |
753 | | inita = ... | |
754 | | initb = ... | |
755 | | loop_1 | |
756 | | a = phi (inita, 2 * b + 3) | |
757 | | b = phi (initb, b + 1) | |
758 | | endloop | |
759 | ||
760 | For the first case, the semantics of the SSA representation is: | |
761 | ||
762 | | a (x) = init + \sum_{j = 0}^{x - 1} expr (j) | |
763 | ||
764 | that is, there is a loop index "x" that determines the scalar value | |
765 | of the variable during the loop execution. During the first | |
766 | iteration, the value is that of the initial condition INIT, while | |
767 | during the subsequent iterations, it is the sum of the initial | |
768 | condition with the sum of all the values of EXPR from the initial | |
769 | iteration to the before last considered iteration. | |
770 | ||
771 | For the second case, the semantics of the SSA program is: | |
772 | ||
773 | | a (x) = init, if x = 0; | |
774 | | expr (x - 1), otherwise. | |
775 | ||
776 | The second case corresponds to the PEELED_CHREC, whose syntax is | |
777 | close to the syntax of a loop-phi-node: | |
778 | ||
779 | | phi (init, expr) vs. (init, expr)_x | |
780 | ||
781 | The proof of the translation algorithm for the first case is a | |
782 | proof by structural induction based on the degree of EXPR. | |
783 | ||
784 | Degree 0: | |
785 | When EXPR is a constant with respect to the analyzed loop, or in | |
786 | other words when EXPR is a polynomial of degree 0, the evolution of | |
787 | the variable A in the loop is an affine function with an initial | |
788 | condition INIT, and a step EXPR. In order to show this, we start | |
789 | from the semantics of the SSA representation: | |
790 | ||
791 | f (x) = init + \sum_{j = 0}^{x - 1} expr (j) | |
792 | ||
793 | and since "expr (j)" is a constant with respect to "j", | |
794 | ||
795 | f (x) = init + x * expr | |
796 | ||
797 | Finally, based on the semantics of the pure sum chrecs, by | |
798 | identification we get the corresponding chrecs syntax: | |
799 | ||
800 | f (x) = init * \binom{x}{0} + expr * \binom{x}{1} | |
801 | f (x) -> {init, +, expr}_x | |
802 | ||
803 | Higher degree: | |
804 | Suppose that EXPR is a polynomial of degree N with respect to the | |
805 | analyzed loop_x for which we have already determined that it is | |
806 | written under the chrecs syntax: | |
807 | ||
808 | | expr (x) -> {b_0, +, b_1, +, ..., +, b_{n-1}} (x) | |
809 | ||
810 | We start from the semantics of the SSA program: | |
811 | ||
812 | | f (x) = init + \sum_{j = 0}^{x - 1} expr (j) | |
813 | | | |
814 | | f (x) = init + \sum_{j = 0}^{x - 1} | |
815 | | (b_0 * \binom{j}{0} + ... + b_{n-1} * \binom{j}{n-1}) | |
816 | | | |
817 | | f (x) = init + \sum_{j = 0}^{x - 1} | |
818 | | \sum_{k = 0}^{n - 1} (b_k * \binom{j}{k}) | |
819 | | | |
820 | | f (x) = init + \sum_{k = 0}^{n - 1} | |
821 | | (b_k * \sum_{j = 0}^{x - 1} \binom{j}{k}) | |
822 | | | |
823 | | f (x) = init + \sum_{k = 0}^{n - 1} | |
824 | | (b_k * \binom{x}{k + 1}) | |
825 | | | |
826 | | f (x) = init + b_0 * \binom{x}{1} + ... | |
827 | | + b_{n-1} * \binom{x}{n} | |
828 | | | |
829 | | f (x) = init * \binom{x}{0} + b_0 * \binom{x}{1} + ... | |
830 | | + b_{n-1} * \binom{x}{n} | |
831 | | | |
832 | ||
833 | And finally from the definition of the chrecs syntax, we identify: | |
834 | | f (x) -> {init, +, b_0, +, ..., +, b_{n-1}}_x | |
835 | ||
836 | This shows the mechanism that stands behind the add_to_evolution | |
837 | function. An important point is that the use of symbolic | |
838 | parameters avoids the need of an analysis schedule. | |
839 | ||
840 | Example: | |
841 | ||
842 | | inita = ... | |
843 | | initb = ... | |
844 | | loop_1 | |
845 | | a = phi (inita, a + 2 + b) | |
846 | | b = phi (initb, b + 1) | |
847 | | endloop | |
848 | ||
849 | When analyzing "a", the algorithm keeps "b" symbolically: | |
850 | ||
851 | | a -> {inita, +, 2 + b}_1 | |
852 | ||
853 | Then, after instantiation, the analyzer ends on the evolution: | |
854 | ||
855 | | a -> {inita, +, 2 + initb, +, 1}_1 | |
856 | ||
857 | */ | |
858 | ||
859 | static tree | |
e2157b49 | 860 | add_to_evolution (unsigned loop_nb, tree chrec_before, enum tree_code code, |
726a989a | 861 | tree to_add, gimple at_stmt) |
9baba81b SP |
862 | { |
863 | tree type = chrec_type (to_add); | |
864 | tree res = NULL_TREE; | |
865 | ||
866 | if (to_add == NULL_TREE) | |
867 | return chrec_before; | |
868 | ||
869 | /* TO_ADD is either a scalar, or a parameter. TO_ADD is not | |
870 | instantiated at this point. */ | |
871 | if (TREE_CODE (to_add) == POLYNOMIAL_CHREC) | |
872 | /* This should not happen. */ | |
873 | return chrec_dont_know; | |
874 | ||
875 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
876 | { | |
877 | fprintf (dump_file, "(add_to_evolution \n"); | |
878 | fprintf (dump_file, " (loop_nb = %d)\n", loop_nb); | |
879 | fprintf (dump_file, " (chrec_before = "); | |
880 | print_generic_expr (dump_file, chrec_before, 0); | |
881 | fprintf (dump_file, ")\n (to_add = "); | |
882 | print_generic_expr (dump_file, to_add, 0); | |
883 | fprintf (dump_file, ")\n"); | |
884 | } | |
885 | ||
886 | if (code == MINUS_EXPR) | |
9d2b0e12 VR |
887 | to_add = chrec_fold_multiply (type, to_add, SCALAR_FLOAT_TYPE_P (type) |
888 | ? build_real (type, dconstm1) | |
889 | : build_int_cst_type (type, -1)); | |
9baba81b | 890 | |
e2157b49 | 891 | res = add_to_evolution_1 (loop_nb, chrec_before, to_add, at_stmt); |
9baba81b SP |
892 | |
893 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
894 | { | |
895 | fprintf (dump_file, " (res = "); | |
896 | print_generic_expr (dump_file, res, 0); | |
897 | fprintf (dump_file, "))\n"); | |
898 | } | |
899 | ||
900 | return res; | |
901 | } | |
902 | ||
903 | /* Helper function. */ | |
904 | ||
905 | static inline tree | |
906 | set_nb_iterations_in_loop (struct loop *loop, | |
907 | tree res) | |
908 | { | |
9baba81b SP |
909 | if (dump_file && (dump_flags & TDF_DETAILS)) |
910 | { | |
911 | fprintf (dump_file, " (set_nb_iterations_in_loop = "); | |
912 | print_generic_expr (dump_file, res, 0); | |
913 | fprintf (dump_file, "))\n"); | |
914 | } | |
915 | ||
916 | loop->nb_iterations = res; | |
917 | return res; | |
918 | } | |
919 | ||
920 | \f | |
921 | ||
922 | /* This section selects the loops that will be good candidates for the | |
923 | scalar evolution analysis. For the moment, greedily select all the | |
924 | loop nests we could analyze. */ | |
925 | ||
9baba81b SP |
926 | /* For a loop with a single exit edge, return the COND_EXPR that |
927 | guards the exit edge. If the expression is too difficult to | |
928 | analyze, then give up. */ | |
929 | ||
726a989a | 930 | gimple |
22ea9ec0 | 931 | get_loop_exit_condition (const struct loop *loop) |
9baba81b | 932 | { |
726a989a | 933 | gimple res = NULL; |
ac8f6c69 | 934 | edge exit_edge = single_exit (loop); |
9baba81b SP |
935 | |
936 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
937 | fprintf (dump_file, "(get_loop_exit_condition \n "); | |
938 | ||
82b85a85 | 939 | if (exit_edge) |
9baba81b | 940 | { |
726a989a | 941 | gimple stmt; |
9baba81b | 942 | |
726a989a RB |
943 | stmt = last_stmt (exit_edge->src); |
944 | if (gimple_code (stmt) == GIMPLE_COND) | |
945 | res = stmt; | |
9baba81b SP |
946 | } |
947 | ||
948 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
949 | { | |
726a989a | 950 | print_gimple_stmt (dump_file, res, 0, 0); |
9baba81b SP |
951 | fprintf (dump_file, ")\n"); |
952 | } | |
953 | ||
954 | return res; | |
955 | } | |
956 | ||
957 | /* Recursively determine and enqueue the exit conditions for a loop. */ | |
958 | ||
959 | static void | |
960 | get_exit_conditions_rec (struct loop *loop, | |
726a989a | 961 | VEC(gimple,heap) **exit_conditions) |
9baba81b SP |
962 | { |
963 | if (!loop) | |
964 | return; | |
965 | ||
966 | /* Recurse on the inner loops, then on the next (sibling) loops. */ | |
967 | get_exit_conditions_rec (loop->inner, exit_conditions); | |
968 | get_exit_conditions_rec (loop->next, exit_conditions); | |
969 | ||
ac8f6c69 | 970 | if (single_exit (loop)) |
9baba81b | 971 | { |
726a989a | 972 | gimple loop_condition = get_loop_exit_condition (loop); |
9baba81b SP |
973 | |
974 | if (loop_condition) | |
726a989a | 975 | VEC_safe_push (gimple, heap, *exit_conditions, loop_condition); |
9baba81b SP |
976 | } |
977 | } | |
978 | ||
979 | /* Select the candidate loop nests for the analysis. This function | |
471854f8 | 980 | initializes the EXIT_CONDITIONS array. */ |
9baba81b SP |
981 | |
982 | static void | |
726a989a | 983 | select_loops_exit_conditions (VEC(gimple,heap) **exit_conditions) |
9baba81b | 984 | { |
d73be268 | 985 | struct loop *function_body = current_loops->tree_root; |
9baba81b SP |
986 | |
987 | get_exit_conditions_rec (function_body->inner, exit_conditions); | |
988 | } | |
989 | ||
990 | \f | |
991 | /* Depth first search algorithm. */ | |
992 | ||
c59dabbe SP |
993 | typedef enum t_bool { |
994 | t_false, | |
995 | t_true, | |
996 | t_dont_know | |
997 | } t_bool; | |
998 | ||
999 | ||
726a989a | 1000 | static t_bool follow_ssa_edge (struct loop *loop, gimple, gimple, tree *, int); |
9baba81b | 1001 | |
726a989a | 1002 | /* Follow the ssa edge into the binary expression RHS0 CODE RHS1. |
9baba81b SP |
1003 | Return true if the strongly connected component has been found. */ |
1004 | ||
c59dabbe | 1005 | static t_bool |
726a989a RB |
1006 | follow_ssa_edge_binary (struct loop *loop, gimple at_stmt, |
1007 | tree type, tree rhs0, enum tree_code code, tree rhs1, | |
1008 | gimple halting_phi, tree *evolution_of_loop, int limit) | |
9baba81b | 1009 | { |
c59dabbe | 1010 | t_bool res = t_false; |
b2a93c0a | 1011 | tree evol; |
726a989a | 1012 | |
5be014d5 | 1013 | switch (code) |
9baba81b | 1014 | { |
5be014d5 | 1015 | case POINTER_PLUS_EXPR: |
9baba81b | 1016 | case PLUS_EXPR: |
9baba81b SP |
1017 | if (TREE_CODE (rhs0) == SSA_NAME) |
1018 | { | |
1019 | if (TREE_CODE (rhs1) == SSA_NAME) | |
1020 | { | |
1021 | /* Match an assignment under the form: | |
1022 | "a = b + c". */ | |
9e824336 ZD |
1023 | |
1024 | /* We want only assignments of form "name + name" contribute to | |
1025 | LIMIT, as the other cases do not necessarily contribute to | |
1026 | the complexity of the expression. */ | |
1027 | limit++; | |
1028 | ||
b2a93c0a | 1029 | evol = *evolution_of_loop; |
9baba81b | 1030 | res = follow_ssa_edge |
726a989a | 1031 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, &evol, limit); |
9baba81b | 1032 | |
c59dabbe | 1033 | if (res == t_true) |
9baba81b SP |
1034 | *evolution_of_loop = add_to_evolution |
1035 | (loop->num, | |
726a989a | 1036 | chrec_convert (type, evol, at_stmt), |
5be014d5 | 1037 | code, rhs1, at_stmt); |
9baba81b | 1038 | |
c59dabbe | 1039 | else if (res == t_false) |
9baba81b SP |
1040 | { |
1041 | res = follow_ssa_edge | |
1042 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
c59dabbe | 1043 | evolution_of_loop, limit); |
9baba81b | 1044 | |
c59dabbe | 1045 | if (res == t_true) |
9baba81b SP |
1046 | *evolution_of_loop = add_to_evolution |
1047 | (loop->num, | |
726a989a | 1048 | chrec_convert (type, *evolution_of_loop, at_stmt), |
5be014d5 | 1049 | code, rhs0, at_stmt); |
c59dabbe SP |
1050 | |
1051 | else if (res == t_dont_know) | |
1052 | *evolution_of_loop = chrec_dont_know; | |
9baba81b | 1053 | } |
c59dabbe SP |
1054 | |
1055 | else if (res == t_dont_know) | |
1056 | *evolution_of_loop = chrec_dont_know; | |
9baba81b SP |
1057 | } |
1058 | ||
1059 | else | |
1060 | { | |
1061 | /* Match an assignment under the form: | |
1062 | "a = b + ...". */ | |
1063 | res = follow_ssa_edge | |
1064 | (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, | |
c59dabbe SP |
1065 | evolution_of_loop, limit); |
1066 | if (res == t_true) | |
9baba81b | 1067 | *evolution_of_loop = add_to_evolution |
726a989a | 1068 | (loop->num, chrec_convert (type, *evolution_of_loop, |
1e8552eb | 1069 | at_stmt), |
5be014d5 | 1070 | code, rhs1, at_stmt); |
c59dabbe SP |
1071 | |
1072 | else if (res == t_dont_know) | |
1073 | *evolution_of_loop = chrec_dont_know; | |
9baba81b SP |
1074 | } |
1075 | } | |
1076 | ||
1077 | else if (TREE_CODE (rhs1) == SSA_NAME) | |
1078 | { | |
1079 | /* Match an assignment under the form: | |
1080 | "a = ... + c". */ | |
1081 | res = follow_ssa_edge | |
1082 | (loop, SSA_NAME_DEF_STMT (rhs1), halting_phi, | |
c59dabbe SP |
1083 | evolution_of_loop, limit); |
1084 | if (res == t_true) | |
9baba81b | 1085 | *evolution_of_loop = add_to_evolution |
726a989a | 1086 | (loop->num, chrec_convert (type, *evolution_of_loop, |
1e8552eb | 1087 | at_stmt), |
5be014d5 | 1088 | code, rhs0, at_stmt); |
c59dabbe SP |
1089 | |
1090 | else if (res == t_dont_know) | |
1091 | *evolution_of_loop = chrec_dont_know; | |
9baba81b SP |
1092 | } |
1093 | ||
1094 | else | |
1095 | /* Otherwise, match an assignment under the form: | |
1096 | "a = ... + ...". */ | |
1097 | /* And there is nothing to do. */ | |
c59dabbe | 1098 | res = t_false; |
9baba81b SP |
1099 | break; |
1100 | ||
1101 | case MINUS_EXPR: | |
1102 | /* This case is under the form "opnd0 = rhs0 - rhs1". */ | |
9baba81b | 1103 | if (TREE_CODE (rhs0) == SSA_NAME) |
9baba81b SP |
1104 | { |
1105 | /* Match an assignment under the form: | |
f8e9d512 | 1106 | "a = b - ...". */ |
9e824336 ZD |
1107 | |
1108 | /* We want only assignments of form "name - name" contribute to | |
1109 | LIMIT, as the other cases do not necessarily contribute to | |
1110 | the complexity of the expression. */ | |
1111 | if (TREE_CODE (rhs1) == SSA_NAME) | |
1112 | limit++; | |
1113 | ||
f8e9d512 | 1114 | res = follow_ssa_edge (loop, SSA_NAME_DEF_STMT (rhs0), halting_phi, |
c59dabbe SP |
1115 | evolution_of_loop, limit); |
1116 | if (res == t_true) | |
9baba81b | 1117 | *evolution_of_loop = add_to_evolution |
726a989a | 1118 | (loop->num, chrec_convert (type, *evolution_of_loop, at_stmt), |
e2157b49 | 1119 | MINUS_EXPR, rhs1, at_stmt); |
c59dabbe SP |
1120 | |
1121 | else if (res == t_dont_know) | |
1122 | *evolution_of_loop = chrec_dont_know; | |
9baba81b | 1123 | } |
9baba81b SP |
1124 | else |
1125 | /* Otherwise, match an assignment under the form: | |
1126 | "a = ... - ...". */ | |
1127 | /* And there is nothing to do. */ | |
c59dabbe | 1128 | res = t_false; |
9baba81b | 1129 | break; |
726a989a RB |
1130 | |
1131 | default: | |
1132 | res = t_false; | |
1133 | } | |
1134 | ||
1135 | return res; | |
1136 | } | |
9baba81b | 1137 | |
726a989a RB |
1138 | /* Follow the ssa edge into the expression EXPR. |
1139 | Return true if the strongly connected component has been found. */ | |
1140 | ||
1141 | static t_bool | |
1142 | follow_ssa_edge_expr (struct loop *loop, gimple at_stmt, tree expr, | |
1143 | gimple halting_phi, tree *evolution_of_loop, int limit) | |
1144 | { | |
1145 | t_bool res = t_false; | |
1146 | tree rhs0, rhs1; | |
1147 | tree type = TREE_TYPE (expr); | |
1148 | enum tree_code code; | |
1149 | ||
1150 | /* The EXPR is one of the following cases: | |
1151 | - an SSA_NAME, | |
1152 | - an INTEGER_CST, | |
1153 | - a PLUS_EXPR, | |
1154 | - a POINTER_PLUS_EXPR, | |
1155 | - a MINUS_EXPR, | |
1156 | - an ASSERT_EXPR, | |
1157 | - other cases are not yet handled. */ | |
1158 | code = TREE_CODE (expr); | |
1159 | switch (code) | |
1160 | { | |
1161 | case NOP_EXPR: | |
1162 | /* This assignment is under the form "a_1 = (cast) rhs. */ | |
1163 | res = follow_ssa_edge_expr (loop, at_stmt, TREE_OPERAND (expr, 0), | |
1164 | halting_phi, evolution_of_loop, limit); | |
1165 | *evolution_of_loop = chrec_convert (type, *evolution_of_loop, at_stmt); | |
1166 | break; | |
1167 | ||
1168 | case INTEGER_CST: | |
1169 | /* This assignment is under the form "a_1 = 7". */ | |
1170 | res = t_false; | |
1171 | break; | |
1172 | ||
1173 | case SSA_NAME: | |
1174 | /* This assignment is under the form: "a_1 = b_2". */ | |
1175 | res = follow_ssa_edge | |
1176 | (loop, SSA_NAME_DEF_STMT (expr), halting_phi, evolution_of_loop, limit); | |
1177 | break; | |
1178 | ||
1179 | case POINTER_PLUS_EXPR: | |
1180 | case PLUS_EXPR: | |
1181 | case MINUS_EXPR: | |
1182 | /* This case is under the form "rhs0 +- rhs1". */ | |
1183 | rhs0 = TREE_OPERAND (expr, 0); | |
1184 | rhs1 = TREE_OPERAND (expr, 1); | |
1185 | STRIP_TYPE_NOPS (rhs0); | |
1186 | STRIP_TYPE_NOPS (rhs1); | |
1187 | return follow_ssa_edge_binary (loop, at_stmt, type, rhs0, code, rhs1, | |
1188 | halting_phi, evolution_of_loop, limit); | |
1189 | ||
0bca51f0 DN |
1190 | case ASSERT_EXPR: |
1191 | { | |
1192 | /* This assignment is of the form: "a_1 = ASSERT_EXPR <a_2, ...>" | |
1193 | It must be handled as a copy assignment of the form a_1 = a_2. */ | |
726a989a | 1194 | tree op0 = ASSERT_EXPR_VAR (expr); |
0bca51f0 DN |
1195 | if (TREE_CODE (op0) == SSA_NAME) |
1196 | res = follow_ssa_edge (loop, SSA_NAME_DEF_STMT (op0), | |
c59dabbe | 1197 | halting_phi, evolution_of_loop, limit); |
0bca51f0 | 1198 | else |
c59dabbe | 1199 | res = t_false; |
0bca51f0 DN |
1200 | break; |
1201 | } | |
1202 | ||
1203 | ||
9baba81b | 1204 | default: |
c59dabbe | 1205 | res = t_false; |
9baba81b SP |
1206 | break; |
1207 | } | |
1208 | ||
1209 | return res; | |
1210 | } | |
1211 | ||
726a989a RB |
1212 | /* Follow the ssa edge into the right hand side of an assignment STMT. |
1213 | Return true if the strongly connected component has been found. */ | |
1214 | ||
1215 | static t_bool | |
1216 | follow_ssa_edge_in_rhs (struct loop *loop, gimple stmt, | |
1217 | gimple halting_phi, tree *evolution_of_loop, int limit) | |
1218 | { | |
1219 | tree type = TREE_TYPE (gimple_assign_lhs (stmt)); | |
1220 | enum tree_code code = gimple_assign_rhs_code (stmt); | |
1221 | ||
1222 | switch (get_gimple_rhs_class (code)) | |
1223 | { | |
1224 | case GIMPLE_BINARY_RHS: | |
1225 | return follow_ssa_edge_binary (loop, stmt, type, | |
1226 | gimple_assign_rhs1 (stmt), code, | |
1227 | gimple_assign_rhs2 (stmt), | |
1228 | halting_phi, evolution_of_loop, limit); | |
1229 | case GIMPLE_SINGLE_RHS: | |
1230 | return follow_ssa_edge_expr (loop, stmt, gimple_assign_rhs1 (stmt), | |
1231 | halting_phi, evolution_of_loop, limit); | |
218d1c24 JJ |
1232 | case GIMPLE_UNARY_RHS: |
1233 | if (code == NOP_EXPR) | |
1234 | { | |
1235 | /* This assignment is under the form "a_1 = (cast) rhs. */ | |
1236 | t_bool res | |
1237 | = follow_ssa_edge_expr (loop, stmt, gimple_assign_rhs1 (stmt), | |
1238 | halting_phi, evolution_of_loop, limit); | |
1239 | *evolution_of_loop = chrec_convert (type, *evolution_of_loop, stmt); | |
1240 | return res; | |
1241 | } | |
1242 | /* FALLTHRU */ | |
1243 | ||
726a989a RB |
1244 | default: |
1245 | return t_false; | |
1246 | } | |
1247 | } | |
1248 | ||
9baba81b SP |
1249 | /* Checks whether the I-th argument of a PHI comes from a backedge. */ |
1250 | ||
1251 | static bool | |
726a989a | 1252 | backedge_phi_arg_p (gimple phi, int i) |
9baba81b | 1253 | { |
726a989a | 1254 | const_edge e = gimple_phi_arg_edge (phi, i); |
9baba81b SP |
1255 | |
1256 | /* We would in fact like to test EDGE_DFS_BACK here, but we do not care | |
1257 | about updating it anywhere, and this should work as well most of the | |
1258 | time. */ | |
1259 | if (e->flags & EDGE_IRREDUCIBLE_LOOP) | |
1260 | return true; | |
1261 | ||
1262 | return false; | |
1263 | } | |
1264 | ||
1265 | /* Helper function for one branch of the condition-phi-node. Return | |
1266 | true if the strongly connected component has been found following | |
1267 | this path. */ | |
1268 | ||
c59dabbe | 1269 | static inline t_bool |
9baba81b SP |
1270 | follow_ssa_edge_in_condition_phi_branch (int i, |
1271 | struct loop *loop, | |
726a989a RB |
1272 | gimple condition_phi, |
1273 | gimple halting_phi, | |
9baba81b | 1274 | tree *evolution_of_branch, |
c59dabbe | 1275 | tree init_cond, int limit) |
9baba81b SP |
1276 | { |
1277 | tree branch = PHI_ARG_DEF (condition_phi, i); | |
1278 | *evolution_of_branch = chrec_dont_know; | |
1279 | ||
1280 | /* Do not follow back edges (they must belong to an irreducible loop, which | |
1281 | we really do not want to worry about). */ | |
1282 | if (backedge_phi_arg_p (condition_phi, i)) | |
c59dabbe | 1283 | return t_false; |
9baba81b SP |
1284 | |
1285 | if (TREE_CODE (branch) == SSA_NAME) | |
1286 | { | |
1287 | *evolution_of_branch = init_cond; | |
1288 | return follow_ssa_edge (loop, SSA_NAME_DEF_STMT (branch), halting_phi, | |
c59dabbe | 1289 | evolution_of_branch, limit); |
9baba81b SP |
1290 | } |
1291 | ||
1292 | /* This case occurs when one of the condition branches sets | |
89dbed81 | 1293 | the variable to a constant: i.e. a phi-node like |
9baba81b SP |
1294 | "a_2 = PHI <a_7(5), 2(6)>;". |
1295 | ||
1296 | FIXME: This case have to be refined correctly: | |
1297 | in some cases it is possible to say something better than | |
1298 | chrec_dont_know, for example using a wrap-around notation. */ | |
c59dabbe | 1299 | return t_false; |
9baba81b SP |
1300 | } |
1301 | ||
1302 | /* This function merges the branches of a condition-phi-node in a | |
1303 | loop. */ | |
1304 | ||
c59dabbe | 1305 | static t_bool |
9baba81b | 1306 | follow_ssa_edge_in_condition_phi (struct loop *loop, |
726a989a RB |
1307 | gimple condition_phi, |
1308 | gimple halting_phi, | |
c59dabbe | 1309 | tree *evolution_of_loop, int limit) |
9baba81b | 1310 | { |
726a989a | 1311 | int i, n; |
9baba81b SP |
1312 | tree init = *evolution_of_loop; |
1313 | tree evolution_of_branch; | |
c59dabbe SP |
1314 | t_bool res = follow_ssa_edge_in_condition_phi_branch (0, loop, condition_phi, |
1315 | halting_phi, | |
1316 | &evolution_of_branch, | |
1317 | init, limit); | |
1318 | if (res == t_false || res == t_dont_know) | |
1319 | return res; | |
9baba81b | 1320 | |
9baba81b SP |
1321 | *evolution_of_loop = evolution_of_branch; |
1322 | ||
9e824336 | 1323 | /* If the phi node is just a copy, do not increase the limit. */ |
726a989a RB |
1324 | n = gimple_phi_num_args (condition_phi); |
1325 | if (n > 1) | |
9e824336 ZD |
1326 | limit++; |
1327 | ||
726a989a | 1328 | for (i = 1; i < n; i++) |
9baba81b | 1329 | { |
e0afb98a SP |
1330 | /* Quickly give up when the evolution of one of the branches is |
1331 | not known. */ | |
1332 | if (*evolution_of_loop == chrec_dont_know) | |
c59dabbe | 1333 | return t_true; |
e0afb98a | 1334 | |
c59dabbe SP |
1335 | res = follow_ssa_edge_in_condition_phi_branch (i, loop, condition_phi, |
1336 | halting_phi, | |
1337 | &evolution_of_branch, | |
1338 | init, limit); | |
1339 | if (res == t_false || res == t_dont_know) | |
1340 | return res; | |
9baba81b SP |
1341 | |
1342 | *evolution_of_loop = chrec_merge (*evolution_of_loop, | |
1343 | evolution_of_branch); | |
1344 | } | |
1345 | ||
c59dabbe | 1346 | return t_true; |
9baba81b SP |
1347 | } |
1348 | ||
1349 | /* Follow an SSA edge in an inner loop. It computes the overall | |
1350 | effect of the loop, and following the symbolic initial conditions, | |
1351 | it follows the edges in the parent loop. The inner loop is | |
1352 | considered as a single statement. */ | |
1353 | ||
c59dabbe | 1354 | static t_bool |
9baba81b | 1355 | follow_ssa_edge_inner_loop_phi (struct loop *outer_loop, |
726a989a RB |
1356 | gimple loop_phi_node, |
1357 | gimple halting_phi, | |
c59dabbe | 1358 | tree *evolution_of_loop, int limit) |
9baba81b SP |
1359 | { |
1360 | struct loop *loop = loop_containing_stmt (loop_phi_node); | |
1361 | tree ev = analyze_scalar_evolution (loop, PHI_RESULT (loop_phi_node)); | |
1362 | ||
1363 | /* Sometimes, the inner loop is too difficult to analyze, and the | |
1364 | result of the analysis is a symbolic parameter. */ | |
1365 | if (ev == PHI_RESULT (loop_phi_node)) | |
1366 | { | |
c59dabbe | 1367 | t_bool res = t_false; |
726a989a | 1368 | int i, n = gimple_phi_num_args (loop_phi_node); |
9baba81b | 1369 | |
726a989a | 1370 | for (i = 0; i < n; i++) |
9baba81b SP |
1371 | { |
1372 | tree arg = PHI_ARG_DEF (loop_phi_node, i); | |
1373 | basic_block bb; | |
1374 | ||
1375 | /* Follow the edges that exit the inner loop. */ | |
726a989a | 1376 | bb = gimple_phi_arg_edge (loop_phi_node, i)->src; |
9baba81b | 1377 | if (!flow_bb_inside_loop_p (loop, bb)) |
726a989a RB |
1378 | res = follow_ssa_edge_expr (outer_loop, loop_phi_node, |
1379 | arg, halting_phi, | |
1380 | evolution_of_loop, limit); | |
c59dabbe SP |
1381 | if (res == t_true) |
1382 | break; | |
9baba81b SP |
1383 | } |
1384 | ||
1385 | /* If the path crosses this loop-phi, give up. */ | |
c59dabbe | 1386 | if (res == t_true) |
9baba81b SP |
1387 | *evolution_of_loop = chrec_dont_know; |
1388 | ||
1389 | return res; | |
1390 | } | |
1391 | ||
1392 | /* Otherwise, compute the overall effect of the inner loop. */ | |
1393 | ev = compute_overall_effect_of_inner_loop (loop, ev); | |
726a989a RB |
1394 | return follow_ssa_edge_expr (outer_loop, loop_phi_node, ev, halting_phi, |
1395 | evolution_of_loop, limit); | |
9baba81b SP |
1396 | } |
1397 | ||
1398 | /* Follow an SSA edge from a loop-phi-node to itself, constructing a | |
1399 | path that is analyzed on the return walk. */ | |
1400 | ||
c59dabbe | 1401 | static t_bool |
726a989a | 1402 | follow_ssa_edge (struct loop *loop, gimple def, gimple halting_phi, |
c59dabbe | 1403 | tree *evolution_of_loop, int limit) |
9baba81b SP |
1404 | { |
1405 | struct loop *def_loop; | |
1406 | ||
726a989a | 1407 | if (gimple_nop_p (def)) |
c59dabbe SP |
1408 | return t_false; |
1409 | ||
1410 | /* Give up if the path is longer than the MAX that we allow. */ | |
9e824336 | 1411 | if (limit > PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE)) |
c59dabbe | 1412 | return t_dont_know; |
9baba81b SP |
1413 | |
1414 | def_loop = loop_containing_stmt (def); | |
1415 | ||
726a989a | 1416 | switch (gimple_code (def)) |
9baba81b | 1417 | { |
726a989a | 1418 | case GIMPLE_PHI: |
9baba81b SP |
1419 | if (!loop_phi_node_p (def)) |
1420 | /* DEF is a condition-phi-node. Follow the branches, and | |
1421 | record their evolutions. Finally, merge the collected | |
1422 | information and set the approximation to the main | |
1423 | variable. */ | |
1424 | return follow_ssa_edge_in_condition_phi | |
c59dabbe | 1425 | (loop, def, halting_phi, evolution_of_loop, limit); |
9baba81b SP |
1426 | |
1427 | /* When the analyzed phi is the halting_phi, the | |
1428 | depth-first search is over: we have found a path from | |
1429 | the halting_phi to itself in the loop. */ | |
1430 | if (def == halting_phi) | |
c59dabbe | 1431 | return t_true; |
9baba81b SP |
1432 | |
1433 | /* Otherwise, the evolution of the HALTING_PHI depends | |
89dbed81 | 1434 | on the evolution of another loop-phi-node, i.e. the |
9baba81b SP |
1435 | evolution function is a higher degree polynomial. */ |
1436 | if (def_loop == loop) | |
c59dabbe | 1437 | return t_false; |
9baba81b SP |
1438 | |
1439 | /* Inner loop. */ | |
1440 | if (flow_loop_nested_p (loop, def_loop)) | |
1441 | return follow_ssa_edge_inner_loop_phi | |
9e824336 | 1442 | (loop, def, halting_phi, evolution_of_loop, limit + 1); |
9baba81b SP |
1443 | |
1444 | /* Outer loop. */ | |
c59dabbe | 1445 | return t_false; |
9baba81b | 1446 | |
726a989a RB |
1447 | case GIMPLE_ASSIGN: |
1448 | return follow_ssa_edge_in_rhs (loop, def, halting_phi, | |
c59dabbe | 1449 | evolution_of_loop, limit); |
9baba81b SP |
1450 | |
1451 | default: | |
1452 | /* At this level of abstraction, the program is just a set | |
726a989a | 1453 | of GIMPLE_ASSIGNs and PHI_NODEs. In principle there is no |
9baba81b | 1454 | other node to be handled. */ |
c59dabbe | 1455 | return t_false; |
9baba81b SP |
1456 | } |
1457 | } | |
1458 | ||
1459 | \f | |
1460 | ||
1461 | /* Given a LOOP_PHI_NODE, this function determines the evolution | |
1462 | function from LOOP_PHI_NODE to LOOP_PHI_NODE in the loop. */ | |
1463 | ||
1464 | static tree | |
726a989a | 1465 | analyze_evolution_in_loop (gimple loop_phi_node, |
9baba81b SP |
1466 | tree init_cond) |
1467 | { | |
726a989a | 1468 | int i, n = gimple_phi_num_args (loop_phi_node); |
9baba81b SP |
1469 | tree evolution_function = chrec_not_analyzed_yet; |
1470 | struct loop *loop = loop_containing_stmt (loop_phi_node); | |
1471 | basic_block bb; | |
1472 | ||
1473 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1474 | { | |
1475 | fprintf (dump_file, "(analyze_evolution_in_loop \n"); | |
1476 | fprintf (dump_file, " (loop_phi_node = "); | |
726a989a | 1477 | print_gimple_stmt (dump_file, loop_phi_node, 0, 0); |
9baba81b SP |
1478 | fprintf (dump_file, ")\n"); |
1479 | } | |
1480 | ||
726a989a | 1481 | for (i = 0; i < n; i++) |
9baba81b SP |
1482 | { |
1483 | tree arg = PHI_ARG_DEF (loop_phi_node, i); | |
726a989a RB |
1484 | gimple ssa_chain; |
1485 | tree ev_fn; | |
874caa00 | 1486 | t_bool res; |
9baba81b SP |
1487 | |
1488 | /* Select the edges that enter the loop body. */ | |
726a989a | 1489 | bb = gimple_phi_arg_edge (loop_phi_node, i)->src; |
9baba81b SP |
1490 | if (!flow_bb_inside_loop_p (loop, bb)) |
1491 | continue; | |
1492 | ||
1493 | if (TREE_CODE (arg) == SSA_NAME) | |
1494 | { | |
1495 | ssa_chain = SSA_NAME_DEF_STMT (arg); | |
1496 | ||
1497 | /* Pass in the initial condition to the follow edge function. */ | |
1498 | ev_fn = init_cond; | |
c59dabbe | 1499 | res = follow_ssa_edge (loop, ssa_chain, loop_phi_node, &ev_fn, 0); |
9baba81b SP |
1500 | } |
1501 | else | |
874caa00 | 1502 | res = t_false; |
9baba81b SP |
1503 | |
1504 | /* When it is impossible to go back on the same | |
1505 | loop_phi_node by following the ssa edges, the | |
89dbed81 | 1506 | evolution is represented by a peeled chrec, i.e. the |
9baba81b SP |
1507 | first iteration, EV_FN has the value INIT_COND, then |
1508 | all the other iterations it has the value of ARG. | |
1509 | For the moment, PEELED_CHREC nodes are not built. */ | |
874caa00 | 1510 | if (res != t_true) |
9baba81b SP |
1511 | ev_fn = chrec_dont_know; |
1512 | ||
1513 | /* When there are multiple back edges of the loop (which in fact never | |
8c27b7d4 | 1514 | happens currently, but nevertheless), merge their evolutions. */ |
9baba81b SP |
1515 | evolution_function = chrec_merge (evolution_function, ev_fn); |
1516 | } | |
1517 | ||
1518 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1519 | { | |
1520 | fprintf (dump_file, " (evolution_function = "); | |
1521 | print_generic_expr (dump_file, evolution_function, 0); | |
1522 | fprintf (dump_file, "))\n"); | |
1523 | } | |
1524 | ||
1525 | return evolution_function; | |
1526 | } | |
1527 | ||
1528 | /* Given a loop-phi-node, return the initial conditions of the | |
1529 | variable on entry of the loop. When the CCP has propagated | |
1530 | constants into the loop-phi-node, the initial condition is | |
1531 | instantiated, otherwise the initial condition is kept symbolic. | |
1532 | This analyzer does not analyze the evolution outside the current | |
1533 | loop, and leaves this task to the on-demand tree reconstructor. */ | |
1534 | ||
1535 | static tree | |
726a989a | 1536 | analyze_initial_condition (gimple loop_phi_node) |
9baba81b | 1537 | { |
726a989a | 1538 | int i, n; |
9baba81b | 1539 | tree init_cond = chrec_not_analyzed_yet; |
726a989a | 1540 | struct loop *loop = loop_containing_stmt (loop_phi_node); |
9baba81b SP |
1541 | |
1542 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1543 | { | |
1544 | fprintf (dump_file, "(analyze_initial_condition \n"); | |
1545 | fprintf (dump_file, " (loop_phi_node = \n"); | |
726a989a | 1546 | print_gimple_stmt (dump_file, loop_phi_node, 0, 0); |
9baba81b SP |
1547 | fprintf (dump_file, ")\n"); |
1548 | } | |
1549 | ||
726a989a RB |
1550 | n = gimple_phi_num_args (loop_phi_node); |
1551 | for (i = 0; i < n; i++) | |
9baba81b SP |
1552 | { |
1553 | tree branch = PHI_ARG_DEF (loop_phi_node, i); | |
726a989a | 1554 | basic_block bb = gimple_phi_arg_edge (loop_phi_node, i)->src; |
9baba81b SP |
1555 | |
1556 | /* When the branch is oriented to the loop's body, it does | |
1557 | not contribute to the initial condition. */ | |
1558 | if (flow_bb_inside_loop_p (loop, bb)) | |
1559 | continue; | |
1560 | ||
1561 | if (init_cond == chrec_not_analyzed_yet) | |
1562 | { | |
1563 | init_cond = branch; | |
1564 | continue; | |
1565 | } | |
1566 | ||
1567 | if (TREE_CODE (branch) == SSA_NAME) | |
1568 | { | |
1569 | init_cond = chrec_dont_know; | |
1570 | break; | |
1571 | } | |
1572 | ||
1573 | init_cond = chrec_merge (init_cond, branch); | |
1574 | } | |
1575 | ||
1576 | /* Ooops -- a loop without an entry??? */ | |
1577 | if (init_cond == chrec_not_analyzed_yet) | |
1578 | init_cond = chrec_dont_know; | |
1579 | ||
1580 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1581 | { | |
1582 | fprintf (dump_file, " (init_cond = "); | |
1583 | print_generic_expr (dump_file, init_cond, 0); | |
1584 | fprintf (dump_file, "))\n"); | |
1585 | } | |
1586 | ||
1587 | return init_cond; | |
1588 | } | |
1589 | ||
1590 | /* Analyze the scalar evolution for LOOP_PHI_NODE. */ | |
1591 | ||
1592 | static tree | |
726a989a | 1593 | interpret_loop_phi (struct loop *loop, gimple loop_phi_node) |
9baba81b SP |
1594 | { |
1595 | tree res; | |
1596 | struct loop *phi_loop = loop_containing_stmt (loop_phi_node); | |
1597 | tree init_cond; | |
1598 | ||
1599 | if (phi_loop != loop) | |
1600 | { | |
1601 | struct loop *subloop; | |
1602 | tree evolution_fn = analyze_scalar_evolution | |
1603 | (phi_loop, PHI_RESULT (loop_phi_node)); | |
1604 | ||
1605 | /* Dive one level deeper. */ | |
9ba025a2 | 1606 | subloop = superloop_at_depth (phi_loop, loop_depth (loop) + 1); |
9baba81b SP |
1607 | |
1608 | /* Interpret the subloop. */ | |
1609 | res = compute_overall_effect_of_inner_loop (subloop, evolution_fn); | |
1610 | return res; | |
1611 | } | |
1612 | ||
1613 | /* Otherwise really interpret the loop phi. */ | |
1614 | init_cond = analyze_initial_condition (loop_phi_node); | |
1615 | res = analyze_evolution_in_loop (loop_phi_node, init_cond); | |
1616 | ||
1617 | return res; | |
1618 | } | |
1619 | ||
1620 | /* This function merges the branches of a condition-phi-node, | |
1621 | contained in the outermost loop, and whose arguments are already | |
1622 | analyzed. */ | |
1623 | ||
1624 | static tree | |
726a989a | 1625 | interpret_condition_phi (struct loop *loop, gimple condition_phi) |
9baba81b | 1626 | { |
726a989a | 1627 | int i, n = gimple_phi_num_args (condition_phi); |
9baba81b SP |
1628 | tree res = chrec_not_analyzed_yet; |
1629 | ||
726a989a | 1630 | for (i = 0; i < n; i++) |
9baba81b SP |
1631 | { |
1632 | tree branch_chrec; | |
1633 | ||
1634 | if (backedge_phi_arg_p (condition_phi, i)) | |
1635 | { | |
1636 | res = chrec_dont_know; | |
1637 | break; | |
1638 | } | |
1639 | ||
1640 | branch_chrec = analyze_scalar_evolution | |
1641 | (loop, PHI_ARG_DEF (condition_phi, i)); | |
1642 | ||
1643 | res = chrec_merge (res, branch_chrec); | |
1644 | } | |
1645 | ||
1646 | return res; | |
1647 | } | |
1648 | ||
726a989a | 1649 | /* Interpret the operation RHS1 OP RHS2. If we didn't |
29836d07 | 1650 | analyze this node before, follow the definitions until ending |
726a989a | 1651 | either on an analyzed GIMPLE_ASSIGN, or on a loop-phi-node. On the |
9baba81b SP |
1652 | return path, this function propagates evolutions (ala constant copy |
1653 | propagation). OPND1 is not a GIMPLE expression because we could | |
1654 | analyze the effect of an inner loop: see interpret_loop_phi. */ | |
1655 | ||
1656 | static tree | |
726a989a RB |
1657 | interpret_rhs_expr (struct loop *loop, gimple at_stmt, |
1658 | tree type, tree rhs1, enum tree_code code, tree rhs2) | |
9baba81b | 1659 | { |
726a989a RB |
1660 | tree res, chrec1, chrec2; |
1661 | ||
1662 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) | |
1663 | { | |
1664 | if (is_gimple_min_invariant (rhs1)) | |
1665 | return chrec_convert (type, rhs1, at_stmt); | |
1666 | ||
1667 | if (code == SSA_NAME) | |
1668 | return chrec_convert (type, analyze_scalar_evolution (loop, rhs1), | |
1669 | at_stmt); | |
1e8552eb | 1670 | |
726a989a RB |
1671 | if (code == ASSERT_EXPR) |
1672 | { | |
1673 | rhs1 = ASSERT_EXPR_VAR (rhs1); | |
1674 | return chrec_convert (type, analyze_scalar_evolution (loop, rhs1), | |
1675 | at_stmt); | |
1676 | } | |
1677 | ||
1678 | return chrec_dont_know; | |
1679 | } | |
1e8552eb | 1680 | |
726a989a | 1681 | switch (code) |
9baba81b | 1682 | { |
5be014d5 | 1683 | case POINTER_PLUS_EXPR: |
726a989a RB |
1684 | chrec1 = analyze_scalar_evolution (loop, rhs1); |
1685 | chrec2 = analyze_scalar_evolution (loop, rhs2); | |
1686 | chrec1 = chrec_convert (type, chrec1, at_stmt); | |
1687 | chrec2 = chrec_convert (sizetype, chrec2, at_stmt); | |
1688 | res = chrec_fold_plus (type, chrec1, chrec2); | |
5be014d5 AP |
1689 | break; |
1690 | ||
9baba81b | 1691 | case PLUS_EXPR: |
726a989a RB |
1692 | chrec1 = analyze_scalar_evolution (loop, rhs1); |
1693 | chrec2 = analyze_scalar_evolution (loop, rhs2); | |
1694 | chrec1 = chrec_convert (type, chrec1, at_stmt); | |
1695 | chrec2 = chrec_convert (type, chrec2, at_stmt); | |
1696 | res = chrec_fold_plus (type, chrec1, chrec2); | |
9baba81b SP |
1697 | break; |
1698 | ||
1699 | case MINUS_EXPR: | |
726a989a RB |
1700 | chrec1 = analyze_scalar_evolution (loop, rhs1); |
1701 | chrec2 = analyze_scalar_evolution (loop, rhs2); | |
1702 | chrec1 = chrec_convert (type, chrec1, at_stmt); | |
1703 | chrec2 = chrec_convert (type, chrec2, at_stmt); | |
1704 | res = chrec_fold_minus (type, chrec1, chrec2); | |
9baba81b SP |
1705 | break; |
1706 | ||
1707 | case NEGATE_EXPR: | |
726a989a RB |
1708 | chrec1 = analyze_scalar_evolution (loop, rhs1); |
1709 | chrec1 = chrec_convert (type, chrec1, at_stmt); | |
9a75ede0 | 1710 | /* TYPE may be integer, real or complex, so use fold_convert. */ |
726a989a | 1711 | res = chrec_fold_multiply (type, chrec1, |
9a75ede0 | 1712 | fold_convert (type, integer_minus_one_node)); |
9baba81b SP |
1713 | break; |
1714 | ||
1715 | case MULT_EXPR: | |
726a989a RB |
1716 | chrec1 = analyze_scalar_evolution (loop, rhs1); |
1717 | chrec2 = analyze_scalar_evolution (loop, rhs2); | |
1718 | chrec1 = chrec_convert (type, chrec1, at_stmt); | |
1719 | chrec2 = chrec_convert (type, chrec2, at_stmt); | |
1720 | res = chrec_fold_multiply (type, chrec1, chrec2); | |
0bca51f0 | 1721 | break; |
9baba81b | 1722 | |
1043771b | 1723 | CASE_CONVERT: |
726a989a RB |
1724 | chrec1 = analyze_scalar_evolution (loop, rhs1); |
1725 | res = chrec_convert (type, chrec1, at_stmt); | |
9baba81b SP |
1726 | break; |
1727 | ||
1728 | default: | |
1729 | res = chrec_dont_know; | |
1730 | break; | |
1731 | } | |
1732 | ||
1733 | return res; | |
1734 | } | |
1735 | ||
726a989a RB |
1736 | /* Interpret the expression EXPR. */ |
1737 | ||
1738 | static tree | |
1739 | interpret_expr (struct loop *loop, gimple at_stmt, tree expr) | |
1740 | { | |
1741 | enum tree_code code; | |
1742 | tree type = TREE_TYPE (expr), op0, op1; | |
1743 | ||
1744 | if (automatically_generated_chrec_p (expr)) | |
1745 | return expr; | |
1746 | ||
1747 | if (TREE_CODE (expr) == POLYNOMIAL_CHREC) | |
1748 | return chrec_dont_know; | |
1749 | ||
1750 | extract_ops_from_tree (expr, &code, &op0, &op1); | |
1751 | ||
1752 | return interpret_rhs_expr (loop, at_stmt, type, | |
1753 | op0, code, op1); | |
1754 | } | |
1755 | ||
1756 | /* Interpret the rhs of the assignment STMT. */ | |
1757 | ||
1758 | static tree | |
1759 | interpret_gimple_assign (struct loop *loop, gimple stmt) | |
1760 | { | |
1761 | tree type = TREE_TYPE (gimple_assign_lhs (stmt)); | |
1762 | enum tree_code code = gimple_assign_rhs_code (stmt); | |
1763 | ||
1764 | return interpret_rhs_expr (loop, stmt, type, | |
1765 | gimple_assign_rhs1 (stmt), code, | |
1766 | gimple_assign_rhs2 (stmt)); | |
1767 | } | |
1768 | ||
9baba81b SP |
1769 | \f |
1770 | ||
1771 | /* This section contains all the entry points: | |
1772 | - number_of_iterations_in_loop, | |
1773 | - analyze_scalar_evolution, | |
1774 | - instantiate_parameters. | |
1775 | */ | |
1776 | ||
1777 | /* Compute and return the evolution function in WRTO_LOOP, the nearest | |
1778 | common ancestor of DEF_LOOP and USE_LOOP. */ | |
1779 | ||
1780 | static tree | |
1781 | compute_scalar_evolution_in_loop (struct loop *wrto_loop, | |
1782 | struct loop *def_loop, | |
1783 | tree ev) | |
1784 | { | |
1785 | tree res; | |
1786 | if (def_loop == wrto_loop) | |
1787 | return ev; | |
1788 | ||
9ba025a2 | 1789 | def_loop = superloop_at_depth (def_loop, loop_depth (wrto_loop) + 1); |
9baba81b SP |
1790 | res = compute_overall_effect_of_inner_loop (def_loop, ev); |
1791 | ||
1792 | return analyze_scalar_evolution_1 (wrto_loop, res, chrec_not_analyzed_yet); | |
1793 | } | |
1794 | ||
1795 | /* Helper recursive function. */ | |
1796 | ||
1797 | static tree | |
1798 | analyze_scalar_evolution_1 (struct loop *loop, tree var, tree res) | |
1799 | { | |
726a989a RB |
1800 | tree type = TREE_TYPE (var); |
1801 | gimple def; | |
9baba81b SP |
1802 | basic_block bb; |
1803 | struct loop *def_loop; | |
1804 | ||
42d375ed | 1805 | if (loop == NULL || TREE_CODE (type) == VECTOR_TYPE) |
9baba81b SP |
1806 | return chrec_dont_know; |
1807 | ||
1808 | if (TREE_CODE (var) != SSA_NAME) | |
726a989a | 1809 | return interpret_expr (loop, NULL, var); |
9baba81b SP |
1810 | |
1811 | def = SSA_NAME_DEF_STMT (var); | |
726a989a | 1812 | bb = gimple_bb (def); |
9baba81b SP |
1813 | def_loop = bb ? bb->loop_father : NULL; |
1814 | ||
1815 | if (bb == NULL | |
1816 | || !flow_bb_inside_loop_p (loop, bb)) | |
1817 | { | |
1818 | /* Keep the symbolic form. */ | |
1819 | res = var; | |
1820 | goto set_and_end; | |
1821 | } | |
1822 | ||
1823 | if (res != chrec_not_analyzed_yet) | |
1824 | { | |
1825 | if (loop != bb->loop_father) | |
1826 | res = compute_scalar_evolution_in_loop | |
1827 | (find_common_loop (loop, bb->loop_father), bb->loop_father, res); | |
1828 | ||
1829 | goto set_and_end; | |
1830 | } | |
1831 | ||
1832 | if (loop != def_loop) | |
1833 | { | |
1834 | res = analyze_scalar_evolution_1 (def_loop, var, chrec_not_analyzed_yet); | |
1835 | res = compute_scalar_evolution_in_loop (loop, def_loop, res); | |
1836 | ||
1837 | goto set_and_end; | |
1838 | } | |
1839 | ||
726a989a | 1840 | switch (gimple_code (def)) |
9baba81b | 1841 | { |
726a989a RB |
1842 | case GIMPLE_ASSIGN: |
1843 | res = interpret_gimple_assign (loop, def); | |
9baba81b SP |
1844 | break; |
1845 | ||
726a989a | 1846 | case GIMPLE_PHI: |
9baba81b SP |
1847 | if (loop_phi_node_p (def)) |
1848 | res = interpret_loop_phi (loop, def); | |
1849 | else | |
1850 | res = interpret_condition_phi (loop, def); | |
1851 | break; | |
1852 | ||
1853 | default: | |
1854 | res = chrec_dont_know; | |
1855 | break; | |
1856 | } | |
1857 | ||
1858 | set_and_end: | |
1859 | ||
1860 | /* Keep the symbolic form. */ | |
1861 | if (res == chrec_dont_know) | |
1862 | res = var; | |
1863 | ||
1864 | if (loop == def_loop) | |
a213b219 | 1865 | set_scalar_evolution (block_before_loop (loop), var, res); |
9baba81b SP |
1866 | |
1867 | return res; | |
1868 | } | |
1869 | ||
1870 | /* Entry point for the scalar evolution analyzer. | |
1871 | Analyzes and returns the scalar evolution of the ssa_name VAR. | |
1872 | LOOP_NB is the identifier number of the loop in which the variable | |
1873 | is used. | |
1874 | ||
1875 | Example of use: having a pointer VAR to a SSA_NAME node, STMT a | |
1876 | pointer to the statement that uses this variable, in order to | |
1877 | determine the evolution function of the variable, use the following | |
1878 | calls: | |
1879 | ||
1880 | unsigned loop_nb = loop_containing_stmt (stmt)->num; | |
1881 | tree chrec_with_symbols = analyze_scalar_evolution (loop_nb, var); | |
3f227a8c | 1882 | tree chrec_instantiated = instantiate_parameters (loop, chrec_with_symbols); |
9baba81b SP |
1883 | */ |
1884 | ||
1885 | tree | |
1886 | analyze_scalar_evolution (struct loop *loop, tree var) | |
1887 | { | |
1888 | tree res; | |
1889 | ||
1890 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1891 | { | |
1892 | fprintf (dump_file, "(analyze_scalar_evolution \n"); | |
1893 | fprintf (dump_file, " (loop_nb = %d)\n", loop->num); | |
1894 | fprintf (dump_file, " (scalar = "); | |
1895 | print_generic_expr (dump_file, var, 0); | |
1896 | fprintf (dump_file, ")\n"); | |
1897 | } | |
1898 | ||
a213b219 SP |
1899 | res = get_scalar_evolution (block_before_loop (loop), var); |
1900 | res = analyze_scalar_evolution_1 (loop, var, res); | |
9baba81b | 1901 | |
9baba81b SP |
1902 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1903 | fprintf (dump_file, ")\n"); | |
1904 | ||
1905 | return res; | |
1906 | } | |
1907 | ||
1908 | /* Analyze scalar evolution of use of VERSION in USE_LOOP with respect to | |
1909 | WRTO_LOOP (which should be a superloop of both USE_LOOP and definition | |
a6f778b2 ZD |
1910 | of VERSION). |
1911 | ||
1912 | FOLDED_CASTS is set to true if resolve_mixers used | |
1913 | chrec_convert_aggressive (TODO -- not really, we are way too conservative | |
1914 | at the moment in order to keep things simple). */ | |
9baba81b SP |
1915 | |
1916 | static tree | |
1917 | analyze_scalar_evolution_in_loop (struct loop *wrto_loop, struct loop *use_loop, | |
a6f778b2 | 1918 | tree version, bool *folded_casts) |
9baba81b SP |
1919 | { |
1920 | bool val = false; | |
a6f778b2 | 1921 | tree ev = version, tmp; |
9baba81b | 1922 | |
a6f778b2 ZD |
1923 | if (folded_casts) |
1924 | *folded_casts = false; | |
9baba81b SP |
1925 | while (1) |
1926 | { | |
a6f778b2 ZD |
1927 | tmp = analyze_scalar_evolution (use_loop, ev); |
1928 | ev = resolve_mixers (use_loop, tmp); | |
1929 | ||
1930 | if (folded_casts && tmp != ev) | |
1931 | *folded_casts = true; | |
9baba81b SP |
1932 | |
1933 | if (use_loop == wrto_loop) | |
1934 | return ev; | |
1935 | ||
1936 | /* If the value of the use changes in the inner loop, we cannot express | |
1937 | its value in the outer loop (we might try to return interval chrec, | |
1938 | but we do not have a user for it anyway) */ | |
1939 | if (!no_evolution_in_loop_p (ev, use_loop->num, &val) | |
1940 | || !val) | |
1941 | return chrec_dont_know; | |
1942 | ||
9ba025a2 | 1943 | use_loop = loop_outer (use_loop); |
9baba81b SP |
1944 | } |
1945 | } | |
1946 | ||
a213b219 SP |
1947 | /* Returns from CACHE the value for VERSION instantiated below |
1948 | INSTANTIATED_BELOW block. */ | |
eb0bc7af ZD |
1949 | |
1950 | static tree | |
a213b219 SP |
1951 | get_instantiated_value (htab_t cache, basic_block instantiated_below, |
1952 | tree version) | |
eb0bc7af ZD |
1953 | { |
1954 | struct scev_info_str *info, pattern; | |
1955 | ||
1956 | pattern.var = version; | |
a213b219 | 1957 | pattern.instantiated_below = instantiated_below; |
858904db | 1958 | info = (struct scev_info_str *) htab_find (cache, &pattern); |
eb0bc7af ZD |
1959 | |
1960 | if (info) | |
1961 | return info->chrec; | |
1962 | else | |
1963 | return NULL_TREE; | |
1964 | } | |
1965 | ||
a213b219 SP |
1966 | /* Sets in CACHE the value of VERSION instantiated below basic block |
1967 | INSTANTIATED_BELOW to VAL. */ | |
eb0bc7af ZD |
1968 | |
1969 | static void | |
a213b219 SP |
1970 | set_instantiated_value (htab_t cache, basic_block instantiated_below, |
1971 | tree version, tree val) | |
eb0bc7af ZD |
1972 | { |
1973 | struct scev_info_str *info, pattern; | |
1974 | PTR *slot; | |
1975 | ||
1976 | pattern.var = version; | |
0bfdfbf6 | 1977 | pattern.instantiated_below = instantiated_below; |
eb0bc7af ZD |
1978 | slot = htab_find_slot (cache, &pattern, INSERT); |
1979 | ||
cceb1885 | 1980 | if (!*slot) |
a213b219 | 1981 | *slot = new_scev_info_str (instantiated_below, version); |
cceb1885 | 1982 | info = (struct scev_info_str *) *slot; |
eb0bc7af ZD |
1983 | info->chrec = val; |
1984 | } | |
1985 | ||
18aed06a SP |
1986 | /* Return the closed_loop_phi node for VAR. If there is none, return |
1987 | NULL_TREE. */ | |
1988 | ||
1989 | static tree | |
1990 | loop_closed_phi_def (tree var) | |
1991 | { | |
1992 | struct loop *loop; | |
1993 | edge exit; | |
726a989a RB |
1994 | gimple phi; |
1995 | gimple_stmt_iterator psi; | |
18aed06a SP |
1996 | |
1997 | if (var == NULL_TREE | |
1998 | || TREE_CODE (var) != SSA_NAME) | |
1999 | return NULL_TREE; | |
2000 | ||
2001 | loop = loop_containing_stmt (SSA_NAME_DEF_STMT (var)); | |
ac8f6c69 | 2002 | exit = single_exit (loop); |
18aed06a SP |
2003 | if (!exit) |
2004 | return NULL_TREE; | |
2005 | ||
726a989a RB |
2006 | for (psi = gsi_start_phis (exit->dest); !gsi_end_p (psi); gsi_next (&psi)) |
2007 | { | |
2008 | phi = gsi_stmt (psi); | |
2009 | if (PHI_ARG_DEF_FROM_EDGE (phi, exit) == var) | |
2010 | return PHI_RESULT (phi); | |
2011 | } | |
18aed06a SP |
2012 | |
2013 | return NULL_TREE; | |
2014 | } | |
2015 | ||
a213b219 | 2016 | /* Analyze all the parameters of the chrec, between INSTANTIATE_BELOW |
5b78fc3e JS |
2017 | and EVOLUTION_LOOP, that were left under a symbolic form. |
2018 | ||
2019 | CHREC is the scalar evolution to instantiate. | |
2020 | ||
2021 | CACHE is the cache of already instantiated values. | |
2022 | ||
2023 | FOLD_CONVERSIONS should be set to true when the conversions that | |
2024 | may wrap in signed/pointer type are folded, as long as the value of | |
2025 | the chrec is preserved. | |
2026 | ||
3f227a8c JS |
2027 | SIZE_EXPR is used for computing the size of the expression to be |
2028 | instantiated, and to stop if it exceeds some limit. */ | |
2282a0e6 | 2029 | |
9baba81b | 2030 | static tree |
a213b219 | 2031 | instantiate_scev_1 (basic_block instantiate_below, |
3f227a8c | 2032 | struct loop *evolution_loop, tree chrec, |
5b78fc3e | 2033 | bool fold_conversions, htab_t cache, int size_expr) |
9baba81b SP |
2034 | { |
2035 | tree res, op0, op1, op2; | |
2036 | basic_block def_bb; | |
2037 | struct loop *def_loop; | |
16a2acea | 2038 | tree type = chrec_type (chrec); |
2282a0e6 | 2039 | |
47ae9e4c SP |
2040 | /* Give up if the expression is larger than the MAX that we allow. */ |
2041 | if (size_expr++ > PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE)) | |
2042 | return chrec_dont_know; | |
2043 | ||
d7770457 SP |
2044 | if (automatically_generated_chrec_p (chrec) |
2045 | || is_gimple_min_invariant (chrec)) | |
9baba81b SP |
2046 | return chrec; |
2047 | ||
2048 | switch (TREE_CODE (chrec)) | |
2049 | { | |
2050 | case SSA_NAME: | |
726a989a | 2051 | def_bb = gimple_bb (SSA_NAME_DEF_STMT (chrec)); |
9baba81b SP |
2052 | |
2053 | /* A parameter (or loop invariant and we do not want to include | |
2054 | evolutions in outer loops), nothing to do. */ | |
2055 | if (!def_bb | |
6a732743 | 2056 | || loop_depth (def_bb->loop_father) == 0 |
a213b219 | 2057 | || dominated_by_p (CDI_DOMINATORS, instantiate_below, def_bb)) |
9baba81b SP |
2058 | return chrec; |
2059 | ||
eb0bc7af ZD |
2060 | /* We cache the value of instantiated variable to avoid exponential |
2061 | time complexity due to reevaluations. We also store the convenient | |
2062 | value in the cache in order to prevent infinite recursion -- we do | |
2063 | not want to instantiate the SSA_NAME if it is in a mixer | |
9baba81b SP |
2064 | structure. This is used for avoiding the instantiation of |
2065 | recursively defined functions, such as: | |
2066 | ||
2067 | | a_2 -> {0, +, 1, +, a_2}_1 */ | |
eb0bc7af | 2068 | |
a213b219 | 2069 | res = get_instantiated_value (cache, instantiate_below, chrec); |
eb0bc7af ZD |
2070 | if (res) |
2071 | return res; | |
2072 | ||
a213b219 SP |
2073 | res = chrec_dont_know; |
2074 | set_instantiated_value (cache, instantiate_below, chrec, res); | |
9baba81b | 2075 | |
3f227a8c | 2076 | def_loop = find_common_loop (evolution_loop, def_bb->loop_father); |
9baba81b SP |
2077 | |
2078 | /* If the analysis yields a parametric chrec, instantiate the | |
eb0bc7af | 2079 | result again. */ |
9baba81b | 2080 | res = analyze_scalar_evolution (def_loop, chrec); |
18aed06a SP |
2081 | |
2082 | /* Don't instantiate loop-closed-ssa phi nodes. */ | |
2083 | if (TREE_CODE (res) == SSA_NAME | |
2084 | && (loop_containing_stmt (SSA_NAME_DEF_STMT (res)) == NULL | |
9ba025a2 ZD |
2085 | || (loop_depth (loop_containing_stmt (SSA_NAME_DEF_STMT (res))) |
2086 | > loop_depth (def_loop)))) | |
18aed06a SP |
2087 | { |
2088 | if (res == chrec) | |
2089 | res = loop_closed_phi_def (chrec); | |
2090 | else | |
2091 | res = chrec; | |
2092 | ||
2093 | if (res == NULL_TREE) | |
2094 | res = chrec_dont_know; | |
2095 | } | |
2096 | ||
2097 | else if (res != chrec_dont_know) | |
a213b219 | 2098 | res = instantiate_scev_1 (instantiate_below, evolution_loop, res, |
5b78fc3e | 2099 | fold_conversions, cache, size_expr); |
18aed06a | 2100 | |
eb0bc7af | 2101 | /* Store the correct value to the cache. */ |
a213b219 | 2102 | set_instantiated_value (cache, instantiate_below, chrec, res); |
9baba81b SP |
2103 | return res; |
2104 | ||
2105 | case POLYNOMIAL_CHREC: | |
a213b219 | 2106 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
5b78fc3e JS |
2107 | CHREC_LEFT (chrec), fold_conversions, cache, |
2108 | size_expr); | |
fca81712 SP |
2109 | if (op0 == chrec_dont_know) |
2110 | return chrec_dont_know; | |
2111 | ||
a213b219 | 2112 | op1 = instantiate_scev_1 (instantiate_below, evolution_loop, |
5b78fc3e JS |
2113 | CHREC_RIGHT (chrec), fold_conversions, cache, |
2114 | size_expr); | |
fca81712 SP |
2115 | if (op1 == chrec_dont_know) |
2116 | return chrec_dont_know; | |
2117 | ||
eac30183 ZD |
2118 | if (CHREC_LEFT (chrec) != op0 |
2119 | || CHREC_RIGHT (chrec) != op1) | |
e2157b49 | 2120 | { |
726a989a | 2121 | op1 = chrec_convert_rhs (chrec_type (op0), op1, NULL); |
e2157b49 SP |
2122 | chrec = build_polynomial_chrec (CHREC_VARIABLE (chrec), op0, op1); |
2123 | } | |
eac30183 | 2124 | return chrec; |
9baba81b | 2125 | |
5be014d5 | 2126 | case POINTER_PLUS_EXPR: |
9baba81b | 2127 | case PLUS_EXPR: |
a213b219 | 2128 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
5b78fc3e | 2129 | TREE_OPERAND (chrec, 0), fold_conversions, cache, |
3f227a8c | 2130 | size_expr); |
fca81712 SP |
2131 | if (op0 == chrec_dont_know) |
2132 | return chrec_dont_know; | |
2133 | ||
a213b219 | 2134 | op1 = instantiate_scev_1 (instantiate_below, evolution_loop, |
5b78fc3e | 2135 | TREE_OPERAND (chrec, 1), fold_conversions, cache, |
3f227a8c | 2136 | size_expr); |
fca81712 SP |
2137 | if (op1 == chrec_dont_know) |
2138 | return chrec_dont_know; | |
2139 | ||
eac30183 ZD |
2140 | if (TREE_OPERAND (chrec, 0) != op0 |
2141 | || TREE_OPERAND (chrec, 1) != op1) | |
16a2acea | 2142 | { |
726a989a RB |
2143 | op0 = chrec_convert (type, op0, NULL); |
2144 | op1 = chrec_convert_rhs (type, op1, NULL); | |
16a2acea SP |
2145 | chrec = chrec_fold_plus (type, op0, op1); |
2146 | } | |
eac30183 | 2147 | return chrec; |
9baba81b SP |
2148 | |
2149 | case MINUS_EXPR: | |
a213b219 | 2150 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
5b78fc3e | 2151 | TREE_OPERAND (chrec, 0), fold_conversions, cache, |
3f227a8c | 2152 | size_expr); |
fca81712 SP |
2153 | if (op0 == chrec_dont_know) |
2154 | return chrec_dont_know; | |
2155 | ||
a213b219 | 2156 | op1 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2157 | TREE_OPERAND (chrec, 1), |
5b78fc3e | 2158 | fold_conversions, cache, size_expr); |
fca81712 SP |
2159 | if (op1 == chrec_dont_know) |
2160 | return chrec_dont_know; | |
2161 | ||
eac30183 ZD |
2162 | if (TREE_OPERAND (chrec, 0) != op0 |
2163 | || TREE_OPERAND (chrec, 1) != op1) | |
16a2acea | 2164 | { |
726a989a RB |
2165 | op0 = chrec_convert (type, op0, NULL); |
2166 | op1 = chrec_convert (type, op1, NULL); | |
16a2acea SP |
2167 | chrec = chrec_fold_minus (type, op0, op1); |
2168 | } | |
eac30183 | 2169 | return chrec; |
9baba81b SP |
2170 | |
2171 | case MULT_EXPR: | |
a213b219 | 2172 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2173 | TREE_OPERAND (chrec, 0), |
5b78fc3e | 2174 | fold_conversions, cache, size_expr); |
fca81712 SP |
2175 | if (op0 == chrec_dont_know) |
2176 | return chrec_dont_know; | |
2177 | ||
a213b219 | 2178 | op1 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2179 | TREE_OPERAND (chrec, 1), |
5b78fc3e | 2180 | fold_conversions, cache, size_expr); |
fca81712 SP |
2181 | if (op1 == chrec_dont_know) |
2182 | return chrec_dont_know; | |
2183 | ||
eac30183 ZD |
2184 | if (TREE_OPERAND (chrec, 0) != op0 |
2185 | || TREE_OPERAND (chrec, 1) != op1) | |
16a2acea | 2186 | { |
726a989a RB |
2187 | op0 = chrec_convert (type, op0, NULL); |
2188 | op1 = chrec_convert (type, op1, NULL); | |
16a2acea SP |
2189 | chrec = chrec_fold_multiply (type, op0, op1); |
2190 | } | |
eac30183 | 2191 | return chrec; |
9baba81b | 2192 | |
1043771b | 2193 | CASE_CONVERT: |
a213b219 | 2194 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2195 | TREE_OPERAND (chrec, 0), |
5b78fc3e | 2196 | fold_conversions, cache, size_expr); |
9baba81b SP |
2197 | if (op0 == chrec_dont_know) |
2198 | return chrec_dont_know; | |
2199 | ||
5b78fc3e | 2200 | if (fold_conversions) |
2282a0e6 ZD |
2201 | { |
2202 | tree tmp = chrec_convert_aggressive (TREE_TYPE (chrec), op0); | |
2203 | if (tmp) | |
2204 | return tmp; | |
2205 | } | |
2206 | ||
eac30183 ZD |
2207 | if (op0 == TREE_OPERAND (chrec, 0)) |
2208 | return chrec; | |
2209 | ||
d7f5de76 ZD |
2210 | /* If we used chrec_convert_aggressive, we can no longer assume that |
2211 | signed chrecs do not overflow, as chrec_convert does, so avoid | |
2212 | calling it in that case. */ | |
5b78fc3e | 2213 | if (fold_conversions) |
d7f5de76 ZD |
2214 | return fold_convert (TREE_TYPE (chrec), op0); |
2215 | ||
726a989a | 2216 | return chrec_convert (TREE_TYPE (chrec), op0, NULL); |
9baba81b SP |
2217 | |
2218 | case SCEV_NOT_KNOWN: | |
2219 | return chrec_dont_know; | |
2220 | ||
2221 | case SCEV_KNOWN: | |
2222 | return chrec_known; | |
2223 | ||
2224 | default: | |
2225 | break; | |
2226 | } | |
2227 | ||
0dfb0dc6 SP |
2228 | if (VL_EXP_CLASS_P (chrec)) |
2229 | return chrec_dont_know; | |
2230 | ||
9baba81b SP |
2231 | switch (TREE_CODE_LENGTH (TREE_CODE (chrec))) |
2232 | { | |
2233 | case 3: | |
a213b219 | 2234 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2235 | TREE_OPERAND (chrec, 0), |
5b78fc3e | 2236 | fold_conversions, cache, size_expr); |
fca81712 SP |
2237 | if (op0 == chrec_dont_know) |
2238 | return chrec_dont_know; | |
2239 | ||
a213b219 | 2240 | op1 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2241 | TREE_OPERAND (chrec, 1), |
5b78fc3e | 2242 | fold_conversions, cache, size_expr); |
fca81712 SP |
2243 | if (op1 == chrec_dont_know) |
2244 | return chrec_dont_know; | |
2245 | ||
a213b219 | 2246 | op2 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2247 | TREE_OPERAND (chrec, 2), |
5b78fc3e | 2248 | fold_conversions, cache, size_expr); |
fca81712 | 2249 | if (op2 == chrec_dont_know) |
9baba81b | 2250 | return chrec_dont_know; |
eac30183 ZD |
2251 | |
2252 | if (op0 == TREE_OPERAND (chrec, 0) | |
2253 | && op1 == TREE_OPERAND (chrec, 1) | |
2254 | && op2 == TREE_OPERAND (chrec, 2)) | |
2255 | return chrec; | |
2256 | ||
987b67bc KH |
2257 | return fold_build3 (TREE_CODE (chrec), |
2258 | TREE_TYPE (chrec), op0, op1, op2); | |
9baba81b SP |
2259 | |
2260 | case 2: | |
a213b219 | 2261 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2262 | TREE_OPERAND (chrec, 0), |
5b78fc3e | 2263 | fold_conversions, cache, size_expr); |
fca81712 SP |
2264 | if (op0 == chrec_dont_know) |
2265 | return chrec_dont_know; | |
2266 | ||
a213b219 | 2267 | op1 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2268 | TREE_OPERAND (chrec, 1), |
5b78fc3e | 2269 | fold_conversions, cache, size_expr); |
fca81712 | 2270 | if (op1 == chrec_dont_know) |
9baba81b | 2271 | return chrec_dont_know; |
eac30183 ZD |
2272 | |
2273 | if (op0 == TREE_OPERAND (chrec, 0) | |
2274 | && op1 == TREE_OPERAND (chrec, 1)) | |
2275 | return chrec; | |
987b67bc | 2276 | return fold_build2 (TREE_CODE (chrec), TREE_TYPE (chrec), op0, op1); |
9baba81b SP |
2277 | |
2278 | case 1: | |
a213b219 | 2279 | op0 = instantiate_scev_1 (instantiate_below, evolution_loop, |
3f227a8c | 2280 | TREE_OPERAND (chrec, 0), |
5b78fc3e | 2281 | fold_conversions, cache, size_expr); |
9baba81b SP |
2282 | if (op0 == chrec_dont_know) |
2283 | return chrec_dont_know; | |
eac30183 ZD |
2284 | if (op0 == TREE_OPERAND (chrec, 0)) |
2285 | return chrec; | |
987b67bc | 2286 | return fold_build1 (TREE_CODE (chrec), TREE_TYPE (chrec), op0); |
9baba81b SP |
2287 | |
2288 | case 0: | |
2289 | return chrec; | |
2290 | ||
2291 | default: | |
2292 | break; | |
2293 | } | |
2294 | ||
2295 | /* Too complicated to handle. */ | |
2296 | return chrec_dont_know; | |
2297 | } | |
e9eb809d ZD |
2298 | |
2299 | /* Analyze all the parameters of the chrec that were left under a | |
a213b219 SP |
2300 | symbolic form. INSTANTIATE_BELOW is the basic block that stops the |
2301 | recursive instantiation of parameters: a parameter is a variable | |
2302 | that is defined in a basic block that dominates INSTANTIATE_BELOW or | |
2303 | a function parameter. */ | |
e9eb809d ZD |
2304 | |
2305 | tree | |
a213b219 | 2306 | instantiate_scev (basic_block instantiate_below, struct loop *evolution_loop, |
3f227a8c | 2307 | tree chrec) |
e9eb809d | 2308 | { |
9baba81b | 2309 | tree res; |
eb0bc7af | 2310 | htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info); |
9baba81b SP |
2311 | |
2312 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2313 | { | |
3f227a8c | 2314 | fprintf (dump_file, "(instantiate_scev \n"); |
a213b219 | 2315 | fprintf (dump_file, " (instantiate_below = %d)\n", instantiate_below->index); |
3f227a8c | 2316 | fprintf (dump_file, " (evolution_loop = %d)\n", evolution_loop->num); |
9baba81b SP |
2317 | fprintf (dump_file, " (chrec = "); |
2318 | print_generic_expr (dump_file, chrec, 0); | |
2319 | fprintf (dump_file, ")\n"); | |
2320 | } | |
2321 | ||
a213b219 | 2322 | res = instantiate_scev_1 (instantiate_below, evolution_loop, chrec, false, |
5b78fc3e | 2323 | cache, 0); |
9baba81b SP |
2324 | |
2325 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2326 | { | |
2327 | fprintf (dump_file, " (res = "); | |
2328 | print_generic_expr (dump_file, res, 0); | |
2329 | fprintf (dump_file, "))\n"); | |
2330 | } | |
eb0bc7af ZD |
2331 | |
2332 | htab_delete (cache); | |
9baba81b SP |
2333 | |
2334 | return res; | |
2335 | } | |
2336 | ||
2337 | /* Similar to instantiate_parameters, but does not introduce the | |
2282a0e6 ZD |
2338 | evolutions in outer loops for LOOP invariants in CHREC, and does not |
2339 | care about causing overflows, as long as they do not affect value | |
2340 | of an expression. */ | |
9baba81b | 2341 | |
3cb960c7 | 2342 | tree |
9baba81b SP |
2343 | resolve_mixers (struct loop *loop, tree chrec) |
2344 | { | |
eb0bc7af | 2345 | htab_t cache = htab_create (10, hash_scev_info, eq_scev_info, del_scev_info); |
a213b219 SP |
2346 | tree ret = instantiate_scev_1 (block_before_loop (loop), loop, chrec, true, |
2347 | cache, 0); | |
eb0bc7af ZD |
2348 | htab_delete (cache); |
2349 | return ret; | |
9baba81b SP |
2350 | } |
2351 | ||
2352 | /* Entry point for the analysis of the number of iterations pass. | |
2353 | This function tries to safely approximate the number of iterations | |
2354 | the loop will run. When this property is not decidable at compile | |
2355 | time, the result is chrec_dont_know. Otherwise the result is | |
2356 | a scalar or a symbolic parameter. | |
2357 | ||
2358 | Example of analysis: suppose that the loop has an exit condition: | |
2359 | ||
2360 | "if (b > 49) goto end_loop;" | |
2361 | ||
2362 | and that in a previous analysis we have determined that the | |
2363 | variable 'b' has an evolution function: | |
2364 | ||
2365 | "EF = {23, +, 5}_2". | |
2366 | ||
2367 | When we evaluate the function at the point 5, i.e. the value of the | |
2368 | variable 'b' after 5 iterations in the loop, we have EF (5) = 48, | |
2369 | and EF (6) = 53. In this case the value of 'b' on exit is '53' and | |
2370 | the loop body has been executed 6 times. */ | |
2371 | ||
2372 | tree | |
a14865db | 2373 | number_of_latch_executions (struct loop *loop) |
9baba81b SP |
2374 | { |
2375 | tree res, type; | |
2376 | edge exit; | |
2377 | struct tree_niter_desc niter_desc; | |
2378 | ||
2379 | /* Determine whether the number_of_iterations_in_loop has already | |
2380 | been computed. */ | |
2381 | res = loop->nb_iterations; | |
2382 | if (res) | |
2383 | return res; | |
2384 | res = chrec_dont_know; | |
2385 | ||
2386 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2387 | fprintf (dump_file, "(number_of_iterations_in_loop\n"); | |
2388 | ||
ac8f6c69 | 2389 | exit = single_exit (loop); |
82b85a85 | 2390 | if (!exit) |
9baba81b | 2391 | goto end; |
9baba81b | 2392 | |
f9cc1a70 | 2393 | if (!number_of_iterations_exit (loop, exit, &niter_desc, false)) |
9baba81b SP |
2394 | goto end; |
2395 | ||
2396 | type = TREE_TYPE (niter_desc.niter); | |
2397 | if (integer_nonzerop (niter_desc.may_be_zero)) | |
5212068f | 2398 | res = build_int_cst (type, 0); |
9baba81b SP |
2399 | else if (integer_zerop (niter_desc.may_be_zero)) |
2400 | res = niter_desc.niter; | |
2401 | else | |
2402 | res = chrec_dont_know; | |
2403 | ||
2404 | end: | |
2405 | return set_nb_iterations_in_loop (loop, res); | |
2406 | } | |
2407 | ||
a14865db ZD |
2408 | /* Returns the number of executions of the exit condition of LOOP, |
2409 | i.e., the number by one higher than number_of_latch_executions. | |
fa10beec | 2410 | Note that unlike number_of_latch_executions, this number does |
a14865db ZD |
2411 | not necessarily fit in the unsigned variant of the type of |
2412 | the control variable -- if the number of iterations is a constant, | |
2413 | we return chrec_dont_know if adding one to number_of_latch_executions | |
2414 | overflows; however, in case the number of iterations is symbolic | |
2415 | expression, the caller is responsible for dealing with this | |
2416 | the possible overflow. */ | |
2417 | ||
2418 | tree | |
2419 | number_of_exit_cond_executions (struct loop *loop) | |
2420 | { | |
2421 | tree ret = number_of_latch_executions (loop); | |
2422 | tree type = chrec_type (ret); | |
2423 | ||
2424 | if (chrec_contains_undetermined (ret)) | |
2425 | return ret; | |
2426 | ||
2427 | ret = chrec_fold_plus (type, ret, build_int_cst (type, 1)); | |
2428 | if (TREE_CODE (ret) == INTEGER_CST | |
2429 | && TREE_OVERFLOW (ret)) | |
2430 | return chrec_dont_know; | |
2431 | ||
2432 | return ret; | |
2433 | } | |
2434 | ||
9baba81b SP |
2435 | /* One of the drivers for testing the scalar evolutions analysis. |
2436 | This function computes the number of iterations for all the loops | |
2437 | from the EXIT_CONDITIONS array. */ | |
2438 | ||
2439 | static void | |
726a989a | 2440 | number_of_iterations_for_all_loops (VEC(gimple,heap) **exit_conditions) |
9baba81b SP |
2441 | { |
2442 | unsigned int i; | |
2443 | unsigned nb_chrec_dont_know_loops = 0; | |
2444 | unsigned nb_static_loops = 0; | |
726a989a | 2445 | gimple cond; |
9baba81b | 2446 | |
726a989a | 2447 | for (i = 0; VEC_iterate (gimple, *exit_conditions, i, cond); i++) |
9baba81b | 2448 | { |
a14865db | 2449 | tree res = number_of_latch_executions (loop_containing_stmt (cond)); |
9baba81b SP |
2450 | if (chrec_contains_undetermined (res)) |
2451 | nb_chrec_dont_know_loops++; | |
2452 | else | |
2453 | nb_static_loops++; | |
2454 | } | |
2455 | ||
2456 | if (dump_file) | |
2457 | { | |
2458 | fprintf (dump_file, "\n(\n"); | |
2459 | fprintf (dump_file, "-----------------------------------------\n"); | |
2460 | fprintf (dump_file, "%d\tnb_chrec_dont_know_loops\n", nb_chrec_dont_know_loops); | |
2461 | fprintf (dump_file, "%d\tnb_static_loops\n", nb_static_loops); | |
42fd6772 | 2462 | fprintf (dump_file, "%d\tnb_total_loops\n", number_of_loops ()); |
9baba81b SP |
2463 | fprintf (dump_file, "-----------------------------------------\n"); |
2464 | fprintf (dump_file, ")\n\n"); | |
2465 | ||
0c8efed8 | 2466 | print_loops (dump_file, 3); |
9baba81b SP |
2467 | } |
2468 | } | |
2469 | ||
2470 | \f | |
2471 | ||
2472 | /* Counters for the stats. */ | |
2473 | ||
2474 | struct chrec_stats | |
2475 | { | |
2476 | unsigned nb_chrecs; | |
2477 | unsigned nb_affine; | |
2478 | unsigned nb_affine_multivar; | |
2479 | unsigned nb_higher_poly; | |
2480 | unsigned nb_chrec_dont_know; | |
2481 | unsigned nb_undetermined; | |
2482 | }; | |
2483 | ||
2484 | /* Reset the counters. */ | |
2485 | ||
2486 | static inline void | |
2487 | reset_chrecs_counters (struct chrec_stats *stats) | |
2488 | { | |
2489 | stats->nb_chrecs = 0; | |
2490 | stats->nb_affine = 0; | |
2491 | stats->nb_affine_multivar = 0; | |
2492 | stats->nb_higher_poly = 0; | |
2493 | stats->nb_chrec_dont_know = 0; | |
2494 | stats->nb_undetermined = 0; | |
2495 | } | |
2496 | ||
2497 | /* Dump the contents of a CHREC_STATS structure. */ | |
2498 | ||
2499 | static void | |
2500 | dump_chrecs_stats (FILE *file, struct chrec_stats *stats) | |
2501 | { | |
2502 | fprintf (file, "\n(\n"); | |
2503 | fprintf (file, "-----------------------------------------\n"); | |
2504 | fprintf (file, "%d\taffine univariate chrecs\n", stats->nb_affine); | |
2505 | fprintf (file, "%d\taffine multivariate chrecs\n", stats->nb_affine_multivar); | |
2506 | fprintf (file, "%d\tdegree greater than 2 polynomials\n", | |
2507 | stats->nb_higher_poly); | |
2508 | fprintf (file, "%d\tchrec_dont_know chrecs\n", stats->nb_chrec_dont_know); | |
2509 | fprintf (file, "-----------------------------------------\n"); | |
2510 | fprintf (file, "%d\ttotal chrecs\n", stats->nb_chrecs); | |
2511 | fprintf (file, "%d\twith undetermined coefficients\n", | |
2512 | stats->nb_undetermined); | |
2513 | fprintf (file, "-----------------------------------------\n"); | |
2514 | fprintf (file, "%d\tchrecs in the scev database\n", | |
2515 | (int) htab_elements (scalar_evolution_info)); | |
2516 | fprintf (file, "%d\tsets in the scev database\n", nb_set_scev); | |
2517 | fprintf (file, "%d\tgets in the scev database\n", nb_get_scev); | |
2518 | fprintf (file, "-----------------------------------------\n"); | |
2519 | fprintf (file, ")\n\n"); | |
2520 | } | |
2521 | ||
2522 | /* Gather statistics about CHREC. */ | |
2523 | ||
2524 | static void | |
2525 | gather_chrec_stats (tree chrec, struct chrec_stats *stats) | |
2526 | { | |
2527 | if (dump_file && (dump_flags & TDF_STATS)) | |
2528 | { | |
2529 | fprintf (dump_file, "(classify_chrec "); | |
2530 | print_generic_expr (dump_file, chrec, 0); | |
2531 | fprintf (dump_file, "\n"); | |
2532 | } | |
2533 | ||
2534 | stats->nb_chrecs++; | |
2535 | ||
2536 | if (chrec == NULL_TREE) | |
2537 | { | |
2538 | stats->nb_undetermined++; | |
2539 | return; | |
2540 | } | |
2541 | ||
2542 | switch (TREE_CODE (chrec)) | |
2543 | { | |
2544 | case POLYNOMIAL_CHREC: | |
2545 | if (evolution_function_is_affine_p (chrec)) | |
2546 | { | |
2547 | if (dump_file && (dump_flags & TDF_STATS)) | |
2548 | fprintf (dump_file, " affine_univariate\n"); | |
2549 | stats->nb_affine++; | |
2550 | } | |
a50411de | 2551 | else if (evolution_function_is_affine_multivariate_p (chrec, 0)) |
9baba81b SP |
2552 | { |
2553 | if (dump_file && (dump_flags & TDF_STATS)) | |
2554 | fprintf (dump_file, " affine_multivariate\n"); | |
2555 | stats->nb_affine_multivar++; | |
2556 | } | |
2557 | else | |
2558 | { | |
2559 | if (dump_file && (dump_flags & TDF_STATS)) | |
2560 | fprintf (dump_file, " higher_degree_polynomial\n"); | |
2561 | stats->nb_higher_poly++; | |
2562 | } | |
2563 | ||
2564 | break; | |
2565 | ||
2566 | default: | |
2567 | break; | |
2568 | } | |
2569 | ||
2570 | if (chrec_contains_undetermined (chrec)) | |
2571 | { | |
2572 | if (dump_file && (dump_flags & TDF_STATS)) | |
2573 | fprintf (dump_file, " undetermined\n"); | |
2574 | stats->nb_undetermined++; | |
2575 | } | |
2576 | ||
2577 | if (dump_file && (dump_flags & TDF_STATS)) | |
2578 | fprintf (dump_file, ")\n"); | |
2579 | } | |
2580 | ||
2581 | /* One of the drivers for testing the scalar evolutions analysis. | |
2582 | This function analyzes the scalar evolution of all the scalars | |
2583 | defined as loop phi nodes in one of the loops from the | |
2584 | EXIT_CONDITIONS array. | |
2585 | ||
2586 | TODO Optimization: A loop is in canonical form if it contains only | |
2587 | a single scalar loop phi node. All the other scalars that have an | |
2588 | evolution in the loop are rewritten in function of this single | |
2589 | index. This allows the parallelization of the loop. */ | |
2590 | ||
2591 | static void | |
726a989a | 2592 | analyze_scalar_evolution_for_all_loop_phi_nodes (VEC(gimple,heap) **exit_conditions) |
9baba81b SP |
2593 | { |
2594 | unsigned int i; | |
2595 | struct chrec_stats stats; | |
726a989a RB |
2596 | gimple cond, phi; |
2597 | gimple_stmt_iterator psi; | |
9baba81b SP |
2598 | |
2599 | reset_chrecs_counters (&stats); | |
2600 | ||
726a989a | 2601 | for (i = 0; VEC_iterate (gimple, *exit_conditions, i, cond); i++) |
9baba81b SP |
2602 | { |
2603 | struct loop *loop; | |
2604 | basic_block bb; | |
726a989a | 2605 | tree chrec; |
9baba81b | 2606 | |
5310bac6 | 2607 | loop = loop_containing_stmt (cond); |
9baba81b SP |
2608 | bb = loop->header; |
2609 | ||
726a989a RB |
2610 | for (psi = gsi_start_phis (bb); !gsi_end_p (psi); gsi_next (&psi)) |
2611 | { | |
2612 | phi = gsi_stmt (psi); | |
2613 | if (is_gimple_reg (PHI_RESULT (phi))) | |
2614 | { | |
2615 | chrec = instantiate_parameters | |
2616 | (loop, | |
2617 | analyze_scalar_evolution (loop, PHI_RESULT (phi))); | |
9baba81b | 2618 | |
726a989a RB |
2619 | if (dump_file && (dump_flags & TDF_STATS)) |
2620 | gather_chrec_stats (chrec, &stats); | |
2621 | } | |
2622 | } | |
9baba81b SP |
2623 | } |
2624 | ||
2625 | if (dump_file && (dump_flags & TDF_STATS)) | |
2626 | dump_chrecs_stats (dump_file, &stats); | |
2627 | } | |
2628 | ||
2629 | /* Callback for htab_traverse, gathers information on chrecs in the | |
2630 | hashtable. */ | |
2631 | ||
2632 | static int | |
2633 | gather_stats_on_scev_database_1 (void **slot, void *stats) | |
2634 | { | |
cceb1885 | 2635 | struct scev_info_str *entry = (struct scev_info_str *) *slot; |
9baba81b | 2636 | |
cceb1885 | 2637 | gather_chrec_stats (entry->chrec, (struct chrec_stats *) stats); |
9baba81b SP |
2638 | |
2639 | return 1; | |
2640 | } | |
2641 | ||
2642 | /* Classify the chrecs of the whole database. */ | |
2643 | ||
2644 | void | |
2645 | gather_stats_on_scev_database (void) | |
2646 | { | |
2647 | struct chrec_stats stats; | |
2648 | ||
2649 | if (!dump_file) | |
2650 | return; | |
2651 | ||
2652 | reset_chrecs_counters (&stats); | |
2653 | ||
2654 | htab_traverse (scalar_evolution_info, gather_stats_on_scev_database_1, | |
2655 | &stats); | |
2656 | ||
2657 | dump_chrecs_stats (dump_file, &stats); | |
2658 | } | |
2659 | ||
2660 | \f | |
2661 | ||
2662 | /* Initializer. */ | |
2663 | ||
2664 | static void | |
2665 | initialize_scalar_evolutions_analyzer (void) | |
2666 | { | |
2667 | /* The elements below are unique. */ | |
2668 | if (chrec_dont_know == NULL_TREE) | |
2669 | { | |
2670 | chrec_not_analyzed_yet = NULL_TREE; | |
2671 | chrec_dont_know = make_node (SCEV_NOT_KNOWN); | |
2672 | chrec_known = make_node (SCEV_KNOWN); | |
d5ab5675 ZD |
2673 | TREE_TYPE (chrec_dont_know) = void_type_node; |
2674 | TREE_TYPE (chrec_known) = void_type_node; | |
9baba81b SP |
2675 | } |
2676 | } | |
2677 | ||
2678 | /* Initialize the analysis of scalar evolutions for LOOPS. */ | |
2679 | ||
2680 | void | |
d73be268 | 2681 | scev_initialize (void) |
9baba81b | 2682 | { |
42fd6772 ZD |
2683 | loop_iterator li; |
2684 | struct loop *loop; | |
9baba81b | 2685 | |
9e2f83a5 ZD |
2686 | scalar_evolution_info = htab_create_alloc (100, |
2687 | hash_scev_info, | |
2688 | eq_scev_info, | |
2689 | del_scev_info, | |
2690 | ggc_calloc, | |
2691 | ggc_free); | |
9baba81b SP |
2692 | |
2693 | initialize_scalar_evolutions_analyzer (); | |
2694 | ||
42fd6772 ZD |
2695 | FOR_EACH_LOOP (li, loop, 0) |
2696 | { | |
2697 | loop->nb_iterations = NULL_TREE; | |
2698 | } | |
9baba81b SP |
2699 | } |
2700 | ||
2701 | /* Cleans up the information cached by the scalar evolutions analysis. */ | |
2702 | ||
2703 | void | |
2704 | scev_reset (void) | |
2705 | { | |
42fd6772 | 2706 | loop_iterator li; |
9baba81b SP |
2707 | struct loop *loop; |
2708 | ||
2709 | if (!scalar_evolution_info || !current_loops) | |
2710 | return; | |
2711 | ||
39f8a3b0 | 2712 | htab_empty (scalar_evolution_info); |
42fd6772 | 2713 | FOR_EACH_LOOP (li, loop, 0) |
9baba81b | 2714 | { |
42fd6772 | 2715 | loop->nb_iterations = NULL_TREE; |
9baba81b | 2716 | } |
e9eb809d ZD |
2717 | } |
2718 | ||
2719 | /* Checks whether OP behaves as a simple affine iv of LOOP in STMT and returns | |
a6f778b2 ZD |
2720 | its base and step in IV if possible. If ALLOW_NONCONSTANT_STEP is true, we |
2721 | want step to be invariant in LOOP. Otherwise we require it to be an | |
2722 | integer constant. IV->no_overflow is set to true if we are sure the iv cannot | |
2723 | overflow (e.g. because it is computed in signed arithmetics). */ | |
e9eb809d ZD |
2724 | |
2725 | bool | |
726a989a | 2726 | simple_iv (struct loop *loop, gimple stmt, tree op, affine_iv *iv, |
9be872b7 | 2727 | bool allow_nonconstant_step) |
e9eb809d | 2728 | { |
726a989a | 2729 | basic_block bb = gimple_bb (stmt); |
9baba81b | 2730 | tree type, ev; |
a6f778b2 | 2731 | bool folded_casts; |
9baba81b | 2732 | |
a6f778b2 ZD |
2733 | iv->base = NULL_TREE; |
2734 | iv->step = NULL_TREE; | |
2735 | iv->no_overflow = false; | |
9baba81b SP |
2736 | |
2737 | type = TREE_TYPE (op); | |
2738 | if (TREE_CODE (type) != INTEGER_TYPE | |
2739 | && TREE_CODE (type) != POINTER_TYPE) | |
2740 | return false; | |
2741 | ||
a6f778b2 ZD |
2742 | ev = analyze_scalar_evolution_in_loop (loop, bb->loop_father, op, |
2743 | &folded_casts); | |
9baba81b SP |
2744 | if (chrec_contains_undetermined (ev)) |
2745 | return false; | |
2746 | ||
2747 | if (tree_does_not_contain_chrecs (ev) | |
2748 | && !chrec_contains_symbols_defined_in_loop (ev, loop->num)) | |
2749 | { | |
a6f778b2 | 2750 | iv->base = ev; |
6e42ce54 | 2751 | iv->step = build_int_cst (TREE_TYPE (ev), 0); |
a6f778b2 | 2752 | iv->no_overflow = true; |
9baba81b SP |
2753 | return true; |
2754 | } | |
2755 | ||
2756 | if (TREE_CODE (ev) != POLYNOMIAL_CHREC | |
2757 | || CHREC_VARIABLE (ev) != (unsigned) loop->num) | |
2758 | return false; | |
2759 | ||
a6f778b2 | 2760 | iv->step = CHREC_RIGHT (ev); |
9be872b7 ZD |
2761 | if (allow_nonconstant_step) |
2762 | { | |
a6f778b2 ZD |
2763 | if (tree_contains_chrecs (iv->step, NULL) |
2764 | || chrec_contains_symbols_defined_in_loop (iv->step, loop->num)) | |
9be872b7 ZD |
2765 | return false; |
2766 | } | |
a6f778b2 | 2767 | else if (TREE_CODE (iv->step) != INTEGER_CST) |
9baba81b | 2768 | return false; |
9be872b7 | 2769 | |
a6f778b2 ZD |
2770 | iv->base = CHREC_LEFT (ev); |
2771 | if (tree_contains_chrecs (iv->base, NULL) | |
2772 | || chrec_contains_symbols_defined_in_loop (iv->base, loop->num)) | |
9baba81b SP |
2773 | return false; |
2774 | ||
eeef0e45 ILT |
2775 | iv->no_overflow = !folded_casts && TYPE_OVERFLOW_UNDEFINED (type); |
2776 | ||
9baba81b SP |
2777 | return true; |
2778 | } | |
2779 | ||
2780 | /* Runs the analysis of scalar evolutions. */ | |
2781 | ||
2782 | void | |
2783 | scev_analysis (void) | |
2784 | { | |
726a989a | 2785 | VEC(gimple,heap) *exit_conditions; |
9baba81b | 2786 | |
726a989a | 2787 | exit_conditions = VEC_alloc (gimple, heap, 37); |
d73be268 | 2788 | select_loops_exit_conditions (&exit_conditions); |
9baba81b SP |
2789 | |
2790 | if (dump_file && (dump_flags & TDF_STATS)) | |
5310bac6 | 2791 | analyze_scalar_evolution_for_all_loop_phi_nodes (&exit_conditions); |
9baba81b | 2792 | |
5310bac6 | 2793 | number_of_iterations_for_all_loops (&exit_conditions); |
726a989a | 2794 | VEC_free (gimple, heap, exit_conditions); |
e9eb809d | 2795 | } |
9baba81b SP |
2796 | |
2797 | /* Finalize the scalar evolution analysis. */ | |
2798 | ||
2799 | void | |
2800 | scev_finalize (void) | |
2801 | { | |
d51157de ZD |
2802 | if (!scalar_evolution_info) |
2803 | return; | |
9baba81b | 2804 | htab_delete (scalar_evolution_info); |
c7b852c8 | 2805 | scalar_evolution_info = NULL; |
9baba81b SP |
2806 | } |
2807 | ||
771f882e ZD |
2808 | /* Returns true if the expression EXPR is considered to be too expensive |
2809 | for scev_const_prop. */ | |
2810 | ||
2811 | bool | |
2812 | expression_expensive_p (tree expr) | |
2813 | { | |
2814 | enum tree_code code; | |
2815 | ||
2816 | if (is_gimple_val (expr)) | |
2817 | return false; | |
2818 | ||
2819 | code = TREE_CODE (expr); | |
2820 | if (code == TRUNC_DIV_EXPR | |
2821 | || code == CEIL_DIV_EXPR | |
2822 | || code == FLOOR_DIV_EXPR | |
2823 | || code == ROUND_DIV_EXPR | |
2824 | || code == TRUNC_MOD_EXPR | |
2825 | || code == CEIL_MOD_EXPR | |
2826 | || code == FLOOR_MOD_EXPR | |
2827 | || code == ROUND_MOD_EXPR | |
2828 | || code == EXACT_DIV_EXPR) | |
2829 | { | |
2830 | /* Division by power of two is usually cheap, so we allow it. | |
2831 | Forbid anything else. */ | |
2832 | if (!integer_pow2p (TREE_OPERAND (expr, 1))) | |
2833 | return true; | |
2834 | } | |
2835 | ||
2836 | switch (TREE_CODE_CLASS (code)) | |
2837 | { | |
2838 | case tcc_binary: | |
2839 | case tcc_comparison: | |
2840 | if (expression_expensive_p (TREE_OPERAND (expr, 1))) | |
2841 | return true; | |
2842 | ||
2843 | /* Fallthru. */ | |
2844 | case tcc_unary: | |
2845 | return expression_expensive_p (TREE_OPERAND (expr, 0)); | |
2846 | ||
2847 | default: | |
2848 | return true; | |
2849 | } | |
2850 | } | |
2851 | ||
684aaf29 | 2852 | /* Replace ssa names for that scev can prove they are constant by the |
3ac01fde ZD |
2853 | appropriate constants. Also perform final value replacement in loops, |
2854 | in case the replacement expressions are cheap. | |
684aaf29 ZD |
2855 | |
2856 | We only consider SSA names defined by phi nodes; rest is left to the | |
2857 | ordinary constant propagation pass. */ | |
2858 | ||
c2924966 | 2859 | unsigned int |
684aaf29 ZD |
2860 | scev_const_prop (void) |
2861 | { | |
2862 | basic_block bb; | |
726a989a RB |
2863 | tree name, type, ev; |
2864 | gimple phi, ass; | |
3ac01fde | 2865 | struct loop *loop, *ex_loop; |
684aaf29 | 2866 | bitmap ssa_names_to_remove = NULL; |
3ac01fde | 2867 | unsigned i; |
42fd6772 | 2868 | loop_iterator li; |
726a989a | 2869 | gimple_stmt_iterator psi; |
684aaf29 | 2870 | |
d51157de | 2871 | if (number_of_loops () <= 1) |
c2924966 | 2872 | return 0; |
684aaf29 ZD |
2873 | |
2874 | FOR_EACH_BB (bb) | |
2875 | { | |
2876 | loop = bb->loop_father; | |
2877 | ||
726a989a | 2878 | for (psi = gsi_start_phis (bb); !gsi_end_p (psi); gsi_next (&psi)) |
684aaf29 | 2879 | { |
726a989a | 2880 | phi = gsi_stmt (psi); |
684aaf29 ZD |
2881 | name = PHI_RESULT (phi); |
2882 | ||
2883 | if (!is_gimple_reg (name)) | |
2884 | continue; | |
2885 | ||
2886 | type = TREE_TYPE (name); | |
2887 | ||
2888 | if (!POINTER_TYPE_P (type) | |
2889 | && !INTEGRAL_TYPE_P (type)) | |
2890 | continue; | |
2891 | ||
2892 | ev = resolve_mixers (loop, analyze_scalar_evolution (loop, name)); | |
2893 | if (!is_gimple_min_invariant (ev) | |
2894 | || !may_propagate_copy (name, ev)) | |
2895 | continue; | |
2896 | ||
2897 | /* Replace the uses of the name. */ | |
18aed06a SP |
2898 | if (name != ev) |
2899 | replace_uses_by (name, ev); | |
684aaf29 ZD |
2900 | |
2901 | if (!ssa_names_to_remove) | |
2902 | ssa_names_to_remove = BITMAP_ALLOC (NULL); | |
2903 | bitmap_set_bit (ssa_names_to_remove, SSA_NAME_VERSION (name)); | |
2904 | } | |
2905 | } | |
2906 | ||
9b3b55a1 DN |
2907 | /* Remove the ssa names that were replaced by constants. We do not |
2908 | remove them directly in the previous cycle, since this | |
2909 | invalidates scev cache. */ | |
684aaf29 ZD |
2910 | if (ssa_names_to_remove) |
2911 | { | |
2912 | bitmap_iterator bi; | |
684aaf29 ZD |
2913 | |
2914 | EXECUTE_IF_SET_IN_BITMAP (ssa_names_to_remove, 0, i, bi) | |
2915 | { | |
726a989a | 2916 | gimple_stmt_iterator psi; |
684aaf29 ZD |
2917 | name = ssa_name (i); |
2918 | phi = SSA_NAME_DEF_STMT (name); | |
2919 | ||
726a989a RB |
2920 | gcc_assert (gimple_code (phi) == GIMPLE_PHI); |
2921 | psi = gsi_for_stmt (phi); | |
2922 | remove_phi_node (&psi, true); | |
684aaf29 ZD |
2923 | } |
2924 | ||
2925 | BITMAP_FREE (ssa_names_to_remove); | |
2926 | scev_reset (); | |
2927 | } | |
3ac01fde ZD |
2928 | |
2929 | /* Now the regular final value replacement. */ | |
42fd6772 | 2930 | FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) |
3ac01fde ZD |
2931 | { |
2932 | edge exit; | |
726a989a RB |
2933 | tree def, rslt, niter; |
2934 | gimple_stmt_iterator bsi; | |
3ac01fde | 2935 | |
3ac01fde ZD |
2936 | /* If we do not know exact number of iterations of the loop, we cannot |
2937 | replace the final value. */ | |
ac8f6c69 | 2938 | exit = single_exit (loop); |
a6f778b2 ZD |
2939 | if (!exit) |
2940 | continue; | |
2941 | ||
a14865db | 2942 | niter = number_of_latch_executions (loop); |
b3ce5b6e | 2943 | if (niter == chrec_dont_know) |
3ac01fde | 2944 | continue; |
925196ed ZD |
2945 | |
2946 | /* Ensure that it is possible to insert new statements somewhere. */ | |
2947 | if (!single_pred_p (exit->dest)) | |
2948 | split_loop_exit_edge (exit); | |
726a989a | 2949 | bsi = gsi_after_labels (exit->dest); |
925196ed | 2950 | |
9ba025a2 ZD |
2951 | ex_loop = superloop_at_depth (loop, |
2952 | loop_depth (exit->dest->loop_father) + 1); | |
3ac01fde | 2953 | |
726a989a | 2954 | for (psi = gsi_start_phis (exit->dest); !gsi_end_p (psi); ) |
3ac01fde | 2955 | { |
726a989a | 2956 | phi = gsi_stmt (psi); |
925196ed | 2957 | rslt = PHI_RESULT (phi); |
3ac01fde | 2958 | def = PHI_ARG_DEF_FROM_EDGE (phi, exit); |
925196ed | 2959 | if (!is_gimple_reg (def)) |
726a989a RB |
2960 | { |
2961 | gsi_next (&psi); | |
2962 | continue; | |
2963 | } | |
3ac01fde ZD |
2964 | |
2965 | if (!POINTER_TYPE_P (TREE_TYPE (def)) | |
2966 | && !INTEGRAL_TYPE_P (TREE_TYPE (def))) | |
726a989a RB |
2967 | { |
2968 | gsi_next (&psi); | |
2969 | continue; | |
2970 | } | |
3ac01fde | 2971 | |
a6f778b2 | 2972 | def = analyze_scalar_evolution_in_loop (ex_loop, loop, def, NULL); |
925196ed | 2973 | def = compute_overall_effect_of_inner_loop (ex_loop, def); |
3ac01fde | 2974 | if (!tree_does_not_contain_chrecs (def) |
e5db3515 ZD |
2975 | || chrec_contains_symbols_defined_in_loop (def, ex_loop->num) |
2976 | /* Moving the computation from the loop may prolong life range | |
2977 | of some ssa names, which may cause problems if they appear | |
2978 | on abnormal edges. */ | |
771f882e ZD |
2979 | || contains_abnormal_ssa_name_p (def) |
2980 | /* Do not emit expensive expressions. The rationale is that | |
2981 | when someone writes a code like | |
2982 | ||
2983 | while (n > 45) n -= 45; | |
2984 | ||
2985 | he probably knows that n is not large, and does not want it | |
2986 | to be turned into n %= 45. */ | |
2987 | || expression_expensive_p (def)) | |
726a989a RB |
2988 | { |
2989 | gsi_next (&psi); | |
2990 | continue; | |
2991 | } | |
3ac01fde | 2992 | |
9b3b55a1 | 2993 | /* Eliminate the PHI node and replace it by a computation outside |
925196ed ZD |
2994 | the loop. */ |
2995 | def = unshare_expr (def); | |
726a989a RB |
2996 | remove_phi_node (&psi, false); |
2997 | ||
2998 | def = force_gimple_operand_gsi (&bsi, def, false, NULL_TREE, | |
2999 | true, GSI_SAME_STMT); | |
3000 | ass = gimple_build_assign (rslt, def); | |
3001 | gsi_insert_before (&bsi, ass, GSI_SAME_STMT); | |
3ac01fde ZD |
3002 | } |
3003 | } | |
c2924966 | 3004 | return 0; |
684aaf29 | 3005 | } |
9e2f83a5 ZD |
3006 | |
3007 | #include "gt-tree-scalar-evolution.h" |