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8dfbf380 | 1 | /* Array prefetching. |
5ebd604f | 2 | Copyright (C) 2005, 2007, 2008, 2009, 2010, 2011 |
3 | Free Software Foundation, Inc. | |
48e1416a | 4 | |
8dfbf380 | 5 | This file is part of GCC. |
48e1416a | 6 | |
8dfbf380 | 7 | GCC is free software; you can redistribute it and/or modify it |
8 | under the terms of the GNU General Public License as published by the | |
8c4c00c1 | 9 | Free Software Foundation; either version 3, or (at your option) any |
8dfbf380 | 10 | later version. |
48e1416a | 11 | |
8dfbf380 | 12 | GCC is distributed in the hope that it will be useful, but WITHOUT |
13 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
48e1416a | 16 | |
8dfbf380 | 17 | You should have received a copy of the GNU General Public License |
8c4c00c1 | 18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ | |
8dfbf380 | 20 | |
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
25 | #include "tree.h" | |
8dfbf380 | 26 | #include "tm_p.h" |
8dfbf380 | 27 | #include "basic-block.h" |
ce084dfc | 28 | #include "tree-pretty-print.h" |
8dfbf380 | 29 | #include "tree-flow.h" |
8dfbf380 | 30 | #include "cfgloop.h" |
8dfbf380 | 31 | #include "tree-pass.h" |
8dfbf380 | 32 | #include "insn-config.h" |
8dfbf380 | 33 | #include "hashtab.h" |
34 | #include "tree-chrec.h" | |
35 | #include "tree-scalar-evolution.h" | |
0b205f4c | 36 | #include "diagnostic-core.h" |
8dfbf380 | 37 | #include "params.h" |
38 | #include "langhooks.h" | |
bc8bb825 | 39 | #include "tree-inline.h" |
5c205353 | 40 | #include "tree-data-ref.h" |
8e3cb73b | 41 | |
42 | ||
43 | /* FIXME: Needed for optabs, but this should all be moved to a TBD interface | |
44 | between the GIMPLE and RTL worlds. */ | |
45 | #include "expr.h" | |
5b5037b3 | 46 | #include "optabs.h" |
aedb7bf8 | 47 | #include "recog.h" |
8dfbf380 | 48 | |
49 | /* This pass inserts prefetch instructions to optimize cache usage during | |
50 | accesses to arrays in loops. It processes loops sequentially and: | |
51 | ||
52 | 1) Gathers all memory references in the single loop. | |
53 | 2) For each of the references it decides when it is profitable to prefetch | |
54 | it. To do it, we evaluate the reuse among the accesses, and determines | |
55 | two values: PREFETCH_BEFORE (meaning that it only makes sense to do | |
56 | prefetching in the first PREFETCH_BEFORE iterations of the loop) and | |
57 | PREFETCH_MOD (meaning that it only makes sense to prefetch in the | |
58 | iterations of the loop that are zero modulo PREFETCH_MOD). For example | |
59 | (assuming cache line size is 64 bytes, char has size 1 byte and there | |
60 | is no hardware sequential prefetch): | |
61 | ||
62 | char *a; | |
63 | for (i = 0; i < max; i++) | |
64 | { | |
65 | a[255] = ...; (0) | |
66 | a[i] = ...; (1) | |
67 | a[i + 64] = ...; (2) | |
68 | a[16*i] = ...; (3) | |
69 | a[187*i] = ...; (4) | |
70 | a[187*i + 50] = ...; (5) | |
71 | } | |
72 | ||
73 | (0) obviously has PREFETCH_BEFORE 1 | |
74 | (1) has PREFETCH_BEFORE 64, since (2) accesses the same memory | |
75 | location 64 iterations before it, and PREFETCH_MOD 64 (since | |
76 | it hits the same cache line otherwise). | |
77 | (2) has PREFETCH_MOD 64 | |
78 | (3) has PREFETCH_MOD 4 | |
79 | (4) has PREFETCH_MOD 1. We do not set PREFETCH_BEFORE here, since | |
66f19dbb | 80 | the cache line accessed by (5) is the same with probability only |
8dfbf380 | 81 | 7/32. |
82 | (5) has PREFETCH_MOD 1 as well. | |
83 | ||
5c205353 | 84 | Additionally, we use data dependence analysis to determine for each |
85 | reference the distance till the first reuse; this information is used | |
86 | to determine the temporality of the issued prefetch instruction. | |
87 | ||
8dfbf380 | 88 | 3) We determine how much ahead we need to prefetch. The number of |
89 | iterations needed is time to fetch / time spent in one iteration of | |
90 | the loop. The problem is that we do not know either of these values, | |
91 | so we just make a heuristic guess based on a magic (possibly) | |
92 | target-specific constant and size of the loop. | |
93 | ||
94 | 4) Determine which of the references we prefetch. We take into account | |
95 | that there is a maximum number of simultaneous prefetches (provided | |
96 | by machine description). We prefetch as many prefetches as possible | |
97 | while still within this bound (starting with those with lowest | |
98 | prefetch_mod, since they are responsible for most of the cache | |
99 | misses). | |
48e1416a | 100 | |
8dfbf380 | 101 | 5) We unroll and peel loops so that we are able to satisfy PREFETCH_MOD |
102 | and PREFETCH_BEFORE requirements (within some bounds), and to avoid | |
103 | prefetching nonaccessed memory. | |
104 | TODO -- actually implement peeling. | |
48e1416a | 105 | |
8dfbf380 | 106 | 6) We actually emit the prefetch instructions. ??? Perhaps emit the |
107 | prefetch instructions with guards in cases where 5) was not sufficient | |
108 | to satisfy the constraints? | |
109 | ||
76595608 | 110 | A cost model is implemented to determine whether or not prefetching is |
111 | profitable for a given loop. The cost model has three heuristics: | |
112 | ||
113 | 1. Function trip_count_to_ahead_ratio_too_small_p implements a | |
114 | heuristic that determines whether or not the loop has too few | |
115 | iterations (compared to ahead). Prefetching is not likely to be | |
116 | beneficial if the trip count to ahead ratio is below a certain | |
117 | minimum. | |
118 | ||
119 | 2. Function mem_ref_count_reasonable_p implements a heuristic that | |
120 | determines whether the given loop has enough CPU ops that can be | |
121 | overlapped with cache missing memory ops. If not, the loop | |
122 | won't benefit from prefetching. In the implementation, | |
123 | prefetching is not considered beneficial if the ratio between | |
124 | the instruction count and the mem ref count is below a certain | |
125 | minimum. | |
126 | ||
127 | 3. Function insn_to_prefetch_ratio_too_small_p implements a | |
128 | heuristic that disables prefetching in a loop if the prefetching | |
129 | cost is above a certain limit. The relative prefetching cost is | |
130 | estimated by taking the ratio between the prefetch count and the | |
131 | total intruction count (this models the I-cache cost). | |
132 | ||
0ab353e1 | 133 | The limits used in these heuristics are defined as parameters with |
48e1416a | 134 | reasonable default values. Machine-specific default values will be |
0ab353e1 | 135 | added later. |
48e1416a | 136 | |
8dfbf380 | 137 | Some other TODO: |
138 | -- write and use more general reuse analysis (that could be also used | |
139 | in other cache aimed loop optimizations) | |
140 | -- make it behave sanely together with the prefetches given by user | |
141 | (now we just ignore them; at the very least we should avoid | |
142 | optimizing loops in that user put his own prefetches) | |
143 | -- we assume cache line size alignment of arrays; this could be | |
144 | improved. */ | |
145 | ||
146 | /* Magic constants follow. These should be replaced by machine specific | |
147 | numbers. */ | |
148 | ||
8dfbf380 | 149 | /* True if write can be prefetched by a read prefetch. */ |
150 | ||
151 | #ifndef WRITE_CAN_USE_READ_PREFETCH | |
152 | #define WRITE_CAN_USE_READ_PREFETCH 1 | |
153 | #endif | |
154 | ||
155 | /* True if read can be prefetched by a write prefetch. */ | |
156 | ||
157 | #ifndef READ_CAN_USE_WRITE_PREFETCH | |
158 | #define READ_CAN_USE_WRITE_PREFETCH 0 | |
159 | #endif | |
160 | ||
07804af5 | 161 | /* The size of the block loaded by a single prefetch. Usually, this is |
162 | the same as cache line size (at the moment, we only consider one level | |
163 | of cache hierarchy). */ | |
8dfbf380 | 164 | |
165 | #ifndef PREFETCH_BLOCK | |
07804af5 | 166 | #define PREFETCH_BLOCK L1_CACHE_LINE_SIZE |
8dfbf380 | 167 | #endif |
168 | ||
169 | /* Do we have a forward hardware sequential prefetching? */ | |
170 | ||
171 | #ifndef HAVE_FORWARD_PREFETCH | |
172 | #define HAVE_FORWARD_PREFETCH 0 | |
173 | #endif | |
174 | ||
175 | /* Do we have a backward hardware sequential prefetching? */ | |
176 | ||
177 | #ifndef HAVE_BACKWARD_PREFETCH | |
178 | #define HAVE_BACKWARD_PREFETCH 0 | |
179 | #endif | |
180 | ||
181 | /* In some cases we are only able to determine that there is a certain | |
182 | probability that the two accesses hit the same cache line. In this | |
183 | case, we issue the prefetches for both of them if this probability | |
f0b5f617 | 184 | is less then (1000 - ACCEPTABLE_MISS_RATE) per thousand. */ |
8dfbf380 | 185 | |
186 | #ifndef ACCEPTABLE_MISS_RATE | |
187 | #define ACCEPTABLE_MISS_RATE 50 | |
188 | #endif | |
189 | ||
190 | #ifndef HAVE_prefetch | |
191 | #define HAVE_prefetch 0 | |
192 | #endif | |
193 | ||
0c916a7b | 194 | #define L1_CACHE_SIZE_BYTES ((unsigned) (L1_CACHE_SIZE * 1024)) |
195 | #define L2_CACHE_SIZE_BYTES ((unsigned) (L2_CACHE_SIZE * 1024)) | |
5c205353 | 196 | |
197 | /* We consider a memory access nontemporal if it is not reused sooner than | |
198 | after L2_CACHE_SIZE_BYTES of memory are accessed. However, we ignore | |
199 | accesses closer than L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION, | |
200 | so that we use nontemporal prefetches e.g. if single memory location | |
201 | is accessed several times in a single iteration of the loop. */ | |
202 | #define NONTEMPORAL_FRACTION 16 | |
203 | ||
5b5037b3 | 204 | /* In case we have to emit a memory fence instruction after the loop that |
205 | uses nontemporal stores, this defines the builtin to use. */ | |
206 | ||
207 | #ifndef FENCE_FOLLOWING_MOVNT | |
208 | #define FENCE_FOLLOWING_MOVNT NULL_TREE | |
209 | #endif | |
210 | ||
e20bb126 | 211 | /* It is not profitable to prefetch when the trip count is not at |
212 | least TRIP_COUNT_TO_AHEAD_RATIO times the prefetch ahead distance. | |
213 | For example, in a loop with a prefetch ahead distance of 10, | |
214 | supposing that TRIP_COUNT_TO_AHEAD_RATIO is equal to 4, it is | |
215 | profitable to prefetch when the trip count is greater or equal to | |
216 | 40. In that case, 30 out of the 40 iterations will benefit from | |
217 | prefetching. */ | |
218 | ||
219 | #ifndef TRIP_COUNT_TO_AHEAD_RATIO | |
220 | #define TRIP_COUNT_TO_AHEAD_RATIO 4 | |
221 | #endif | |
222 | ||
8dfbf380 | 223 | /* The group of references between that reuse may occur. */ |
224 | ||
225 | struct mem_ref_group | |
226 | { | |
227 | tree base; /* Base of the reference. */ | |
81d2a38f | 228 | tree step; /* Step of the reference. */ |
8dfbf380 | 229 | struct mem_ref *refs; /* References in the group. */ |
230 | struct mem_ref_group *next; /* Next group of references. */ | |
231 | }; | |
232 | ||
233 | /* Assigned to PREFETCH_BEFORE when all iterations are to be prefetched. */ | |
234 | ||
235 | #define PREFETCH_ALL (~(unsigned HOST_WIDE_INT) 0) | |
236 | ||
c0a0de5e | 237 | /* Do not generate a prefetch if the unroll factor is significantly less |
238 | than what is required by the prefetch. This is to avoid redundant | |
1aabe697 | 239 | prefetches. For example, when prefetch_mod is 16 and unroll_factor is |
240 | 2, prefetching requires unrolling the loop 16 times, but | |
241 | the loop is actually unrolled twice. In this case (ratio = 8), | |
c0a0de5e | 242 | prefetching is not likely to be beneficial. */ |
243 | ||
244 | #ifndef PREFETCH_MOD_TO_UNROLL_FACTOR_RATIO | |
1aabe697 | 245 | #define PREFETCH_MOD_TO_UNROLL_FACTOR_RATIO 4 |
c0a0de5e | 246 | #endif |
247 | ||
76595608 | 248 | /* Some of the prefetch computations have quadratic complexity. We want to |
249 | avoid huge compile times and, therefore, want to limit the amount of | |
250 | memory references per loop where we consider prefetching. */ | |
251 | ||
252 | #ifndef PREFETCH_MAX_MEM_REFS_PER_LOOP | |
253 | #define PREFETCH_MAX_MEM_REFS_PER_LOOP 200 | |
254 | #endif | |
255 | ||
8dfbf380 | 256 | /* The memory reference. */ |
257 | ||
258 | struct mem_ref | |
259 | { | |
75a70cf9 | 260 | gimple stmt; /* Statement in that the reference appears. */ |
8dfbf380 | 261 | tree mem; /* The reference. */ |
262 | HOST_WIDE_INT delta; /* Constant offset of the reference. */ | |
8dfbf380 | 263 | struct mem_ref_group *group; /* The group of references it belongs to. */ |
264 | unsigned HOST_WIDE_INT prefetch_mod; | |
265 | /* Prefetch only each PREFETCH_MOD-th | |
266 | iteration. */ | |
267 | unsigned HOST_WIDE_INT prefetch_before; | |
268 | /* Prefetch only first PREFETCH_BEFORE | |
269 | iterations. */ | |
5c205353 | 270 | unsigned reuse_distance; /* The amount of data accessed before the first |
271 | reuse of this value. */ | |
8dfbf380 | 272 | struct mem_ref *next; /* The next reference in the group. */ |
5b5037b3 | 273 | unsigned write_p : 1; /* Is it a write? */ |
274 | unsigned independent_p : 1; /* True if the reference is independent on | |
275 | all other references inside the loop. */ | |
276 | unsigned issue_prefetch_p : 1; /* Should we really issue the prefetch? */ | |
277 | unsigned storent_p : 1; /* True if we changed the store to a | |
278 | nontemporal one. */ | |
8dfbf380 | 279 | }; |
280 | ||
7b64e7e0 | 281 | /* Dumps information about memory reference */ |
8dfbf380 | 282 | static void |
7b64e7e0 | 283 | dump_mem_details (FILE *file, tree base, tree step, |
284 | HOST_WIDE_INT delta, bool write_p) | |
8dfbf380 | 285 | { |
7b64e7e0 | 286 | fprintf (file, "(base "); |
287 | print_generic_expr (file, base, TDF_SLIM); | |
8dfbf380 | 288 | fprintf (file, ", step "); |
7b64e7e0 | 289 | if (cst_and_fits_in_hwi (step)) |
290 | fprintf (file, HOST_WIDE_INT_PRINT_DEC, int_cst_value (step)); | |
81d2a38f | 291 | else |
7b64e7e0 | 292 | print_generic_expr (file, step, TDF_TREE); |
8dfbf380 | 293 | fprintf (file, ")\n"); |
1da72d7c | 294 | fprintf (file, " delta "); |
7b64e7e0 | 295 | fprintf (file, HOST_WIDE_INT_PRINT_DEC, delta); |
296 | fprintf (file, "\n"); | |
297 | fprintf (file, " %s\n", write_p ? "write" : "read"); | |
8dfbf380 | 298 | fprintf (file, "\n"); |
7b64e7e0 | 299 | } |
8dfbf380 | 300 | |
7b64e7e0 | 301 | /* Dumps information about reference REF to FILE. */ |
8dfbf380 | 302 | |
7b64e7e0 | 303 | static void |
304 | dump_mem_ref (FILE *file, struct mem_ref *ref) | |
305 | { | |
306 | fprintf (file, "Reference %p:\n", (void *) ref); | |
307 | ||
308 | fprintf (file, " group %p ", (void *) ref->group); | |
309 | ||
310 | dump_mem_details (file, ref->group->base, ref->group->step, ref->delta, | |
311 | ref->write_p); | |
8dfbf380 | 312 | } |
313 | ||
314 | /* Finds a group with BASE and STEP in GROUPS, or creates one if it does not | |
315 | exist. */ | |
316 | ||
317 | static struct mem_ref_group * | |
81d2a38f | 318 | find_or_create_group (struct mem_ref_group **groups, tree base, tree step) |
8dfbf380 | 319 | { |
320 | struct mem_ref_group *group; | |
321 | ||
322 | for (; *groups; groups = &(*groups)->next) | |
323 | { | |
81d2a38f | 324 | if (operand_equal_p ((*groups)->step, step, 0) |
8dfbf380 | 325 | && operand_equal_p ((*groups)->base, base, 0)) |
326 | return *groups; | |
327 | ||
81d2a38f | 328 | /* If step is an integer constant, keep the list of groups sorted |
329 | by decreasing step. */ | |
330 | if (cst_and_fits_in_hwi ((*groups)->step) && cst_and_fits_in_hwi (step) | |
331 | && int_cst_value ((*groups)->step) < int_cst_value (step)) | |
8dfbf380 | 332 | break; |
333 | } | |
334 | ||
5c205353 | 335 | group = XNEW (struct mem_ref_group); |
8dfbf380 | 336 | group->base = base; |
337 | group->step = step; | |
338 | group->refs = NULL; | |
339 | group->next = *groups; | |
340 | *groups = group; | |
341 | ||
342 | return group; | |
343 | } | |
344 | ||
345 | /* Records a memory reference MEM in GROUP with offset DELTA and write status | |
346 | WRITE_P. The reference occurs in statement STMT. */ | |
347 | ||
348 | static void | |
75a70cf9 | 349 | record_ref (struct mem_ref_group *group, gimple stmt, tree mem, |
8dfbf380 | 350 | HOST_WIDE_INT delta, bool write_p) |
351 | { | |
352 | struct mem_ref **aref; | |
353 | ||
354 | /* Do not record the same address twice. */ | |
355 | for (aref = &group->refs; *aref; aref = &(*aref)->next) | |
356 | { | |
357 | /* It does not have to be possible for write reference to reuse the read | |
358 | prefetch, or vice versa. */ | |
359 | if (!WRITE_CAN_USE_READ_PREFETCH | |
360 | && write_p | |
361 | && !(*aref)->write_p) | |
362 | continue; | |
363 | if (!READ_CAN_USE_WRITE_PREFETCH | |
364 | && !write_p | |
365 | && (*aref)->write_p) | |
366 | continue; | |
367 | ||
368 | if ((*aref)->delta == delta) | |
369 | return; | |
370 | } | |
371 | ||
5c205353 | 372 | (*aref) = XNEW (struct mem_ref); |
8dfbf380 | 373 | (*aref)->stmt = stmt; |
374 | (*aref)->mem = mem; | |
375 | (*aref)->delta = delta; | |
376 | (*aref)->write_p = write_p; | |
377 | (*aref)->prefetch_before = PREFETCH_ALL; | |
378 | (*aref)->prefetch_mod = 1; | |
5c205353 | 379 | (*aref)->reuse_distance = 0; |
8dfbf380 | 380 | (*aref)->issue_prefetch_p = false; |
381 | (*aref)->group = group; | |
382 | (*aref)->next = NULL; | |
5b5037b3 | 383 | (*aref)->independent_p = false; |
384 | (*aref)->storent_p = false; | |
8dfbf380 | 385 | |
386 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
387 | dump_mem_ref (dump_file, *aref); | |
388 | } | |
389 | ||
390 | /* Release memory references in GROUPS. */ | |
391 | ||
392 | static void | |
393 | release_mem_refs (struct mem_ref_group *groups) | |
394 | { | |
395 | struct mem_ref_group *next_g; | |
396 | struct mem_ref *ref, *next_r; | |
397 | ||
398 | for (; groups; groups = next_g) | |
399 | { | |
400 | next_g = groups->next; | |
401 | for (ref = groups->refs; ref; ref = next_r) | |
402 | { | |
403 | next_r = ref->next; | |
404 | free (ref); | |
405 | } | |
406 | free (groups); | |
407 | } | |
408 | } | |
409 | ||
410 | /* A structure used to pass arguments to idx_analyze_ref. */ | |
411 | ||
412 | struct ar_data | |
413 | { | |
414 | struct loop *loop; /* Loop of the reference. */ | |
75a70cf9 | 415 | gimple stmt; /* Statement of the reference. */ |
81d2a38f | 416 | tree *step; /* Step of the memory reference. */ |
8dfbf380 | 417 | HOST_WIDE_INT *delta; /* Offset of the memory reference. */ |
418 | }; | |
419 | ||
420 | /* Analyzes a single INDEX of a memory reference to obtain information | |
421 | described at analyze_ref. Callback for for_each_index. */ | |
422 | ||
423 | static bool | |
424 | idx_analyze_ref (tree base, tree *index, void *data) | |
425 | { | |
f0d6e81c | 426 | struct ar_data *ar_data = (struct ar_data *) data; |
8dfbf380 | 427 | tree ibase, step, stepsize; |
81d2a38f | 428 | HOST_WIDE_INT idelta = 0, imult = 1; |
8dfbf380 | 429 | affine_iv iv; |
430 | ||
76610704 | 431 | if (!simple_iv (ar_data->loop, loop_containing_stmt (ar_data->stmt), |
81d2a38f | 432 | *index, &iv, true)) |
8dfbf380 | 433 | return false; |
434 | ibase = iv.base; | |
435 | step = iv.step; | |
436 | ||
0de36bdb | 437 | if (TREE_CODE (ibase) == POINTER_PLUS_EXPR |
8dfbf380 | 438 | && cst_and_fits_in_hwi (TREE_OPERAND (ibase, 1))) |
439 | { | |
440 | idelta = int_cst_value (TREE_OPERAND (ibase, 1)); | |
441 | ibase = TREE_OPERAND (ibase, 0); | |
442 | } | |
443 | if (cst_and_fits_in_hwi (ibase)) | |
444 | { | |
445 | idelta += int_cst_value (ibase); | |
05db596e | 446 | ibase = build_int_cst (TREE_TYPE (ibase), 0); |
8dfbf380 | 447 | } |
448 | ||
449 | if (TREE_CODE (base) == ARRAY_REF) | |
450 | { | |
451 | stepsize = array_ref_element_size (base); | |
452 | if (!cst_and_fits_in_hwi (stepsize)) | |
453 | return false; | |
454 | imult = int_cst_value (stepsize); | |
f547ca12 | 455 | step = fold_build2 (MULT_EXPR, sizetype, |
456 | fold_convert (sizetype, step), | |
457 | fold_convert (sizetype, stepsize)); | |
8dfbf380 | 458 | idelta *= imult; |
459 | } | |
460 | ||
f547ca12 | 461 | if (*ar_data->step == NULL_TREE) |
462 | *ar_data->step = step; | |
463 | else | |
464 | *ar_data->step = fold_build2 (PLUS_EXPR, sizetype, | |
465 | fold_convert (sizetype, *ar_data->step), | |
466 | fold_convert (sizetype, step)); | |
8dfbf380 | 467 | *ar_data->delta += idelta; |
468 | *index = ibase; | |
469 | ||
470 | return true; | |
471 | } | |
472 | ||
6dce7ee9 | 473 | /* Tries to express REF_P in shape &BASE + STEP * iter + DELTA, where DELTA and |
8dfbf380 | 474 | STEP are integer constants and iter is number of iterations of LOOP. The |
6dce7ee9 | 475 | reference occurs in statement STMT. Strips nonaddressable component |
476 | references from REF_P. */ | |
8dfbf380 | 477 | |
478 | static bool | |
6dce7ee9 | 479 | analyze_ref (struct loop *loop, tree *ref_p, tree *base, |
81d2a38f | 480 | tree *step, HOST_WIDE_INT *delta, |
75a70cf9 | 481 | gimple stmt) |
8dfbf380 | 482 | { |
483 | struct ar_data ar_data; | |
484 | tree off; | |
485 | HOST_WIDE_INT bit_offset; | |
6dce7ee9 | 486 | tree ref = *ref_p; |
8dfbf380 | 487 | |
81d2a38f | 488 | *step = NULL_TREE; |
8dfbf380 | 489 | *delta = 0; |
490 | ||
0e948838 | 491 | /* First strip off the component references. Ignore bitfields. |
492 | Also strip off the real and imagine parts of a complex, so that | |
493 | they can have the same base. */ | |
494 | if (TREE_CODE (ref) == REALPART_EXPR | |
495 | || TREE_CODE (ref) == IMAGPART_EXPR | |
496 | || (TREE_CODE (ref) == COMPONENT_REF | |
497 | && DECL_NONADDRESSABLE_P (TREE_OPERAND (ref, 1)))) | |
498 | { | |
499 | if (TREE_CODE (ref) == IMAGPART_EXPR) | |
500 | *delta += int_size_in_bytes (TREE_TYPE (ref)); | |
501 | ref = TREE_OPERAND (ref, 0); | |
502 | } | |
8dfbf380 | 503 | |
6dce7ee9 | 504 | *ref_p = ref; |
505 | ||
8dfbf380 | 506 | for (; TREE_CODE (ref) == COMPONENT_REF; ref = TREE_OPERAND (ref, 0)) |
507 | { | |
508 | off = DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1)); | |
509 | bit_offset = TREE_INT_CST_LOW (off); | |
510 | gcc_assert (bit_offset % BITS_PER_UNIT == 0); | |
48e1416a | 511 | |
8dfbf380 | 512 | *delta += bit_offset / BITS_PER_UNIT; |
513 | } | |
514 | ||
515 | *base = unshare_expr (ref); | |
516 | ar_data.loop = loop; | |
517 | ar_data.stmt = stmt; | |
518 | ar_data.step = step; | |
519 | ar_data.delta = delta; | |
520 | return for_each_index (base, idx_analyze_ref, &ar_data); | |
521 | } | |
522 | ||
523 | /* Record a memory reference REF to the list REFS. The reference occurs in | |
5b5037b3 | 524 | LOOP in statement STMT and it is write if WRITE_P. Returns true if the |
525 | reference was recorded, false otherwise. */ | |
8dfbf380 | 526 | |
5b5037b3 | 527 | static bool |
8dfbf380 | 528 | gather_memory_references_ref (struct loop *loop, struct mem_ref_group **refs, |
75a70cf9 | 529 | tree ref, bool write_p, gimple stmt) |
8dfbf380 | 530 | { |
81d2a38f | 531 | tree base, step; |
532 | HOST_WIDE_INT delta; | |
8dfbf380 | 533 | struct mem_ref_group *agrp; |
534 | ||
5d4305e1 | 535 | if (get_base_address (ref) == NULL) |
536 | return false; | |
537 | ||
6dce7ee9 | 538 | if (!analyze_ref (loop, &ref, &base, &step, &delta, stmt)) |
5b5037b3 | 539 | return false; |
81d2a38f | 540 | /* If analyze_ref fails the default is a NULL_TREE. We can stop here. */ |
541 | if (step == NULL_TREE) | |
542 | return false; | |
8dfbf380 | 543 | |
bd62669e | 544 | /* Stop if the address of BASE could not be taken. */ |
09a6f6f5 | 545 | if (may_be_nonaddressable_p (base)) |
546 | return false; | |
547 | ||
7b64e7e0 | 548 | /* Limit non-constant step prefetching only to the innermost loops and |
549 | only when the step is loop invariant in the entire loop nest. */ | |
550 | if (!cst_and_fits_in_hwi (step)) | |
551 | { | |
552 | if (loop->inner != NULL) | |
553 | { | |
554 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
555 | { | |
556 | fprintf (dump_file, "Memory expression %p\n",(void *) ref ); | |
557 | print_generic_expr (dump_file, ref, TDF_TREE); | |
558 | fprintf (dump_file,":"); | |
559 | dump_mem_details( dump_file, base, step, delta, write_p); | |
560 | fprintf (dump_file, | |
561 | "Ignoring %p, non-constant step prefetching is " | |
562 | "limited to inner most loops \n", | |
563 | (void *) ref); | |
564 | } | |
565 | return false; | |
566 | } | |
567 | else | |
568 | { | |
569 | if (!expr_invariant_in_loop_p (loop_outermost (loop), step)) | |
570 | { | |
571 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
572 | { | |
573 | fprintf (dump_file, "Memory expression %p\n",(void *) ref ); | |
574 | print_generic_expr (dump_file, ref, TDF_TREE); | |
575 | fprintf (dump_file,":"); | |
576 | dump_mem_details(dump_file, base, step, delta, write_p); | |
577 | fprintf (dump_file, | |
578 | "Not prefetching, ignoring %p due to " | |
579 | "loop variant step\n", | |
580 | (void *) ref); | |
581 | } | |
582 | return false; | |
583 | } | |
584 | } | |
585 | } | |
94ce9ff0 | 586 | |
8dfbf380 | 587 | /* Now we know that REF = &BASE + STEP * iter + DELTA, where DELTA and STEP |
588 | are integer constants. */ | |
589 | agrp = find_or_create_group (refs, base, step); | |
590 | record_ref (agrp, stmt, ref, delta, write_p); | |
5b5037b3 | 591 | |
592 | return true; | |
8dfbf380 | 593 | } |
594 | ||
5b5037b3 | 595 | /* Record the suitable memory references in LOOP. NO_OTHER_REFS is set to |
596 | true if there are no other memory references inside the loop. */ | |
8dfbf380 | 597 | |
598 | static struct mem_ref_group * | |
0ab353e1 | 599 | gather_memory_references (struct loop *loop, bool *no_other_refs, unsigned *ref_count) |
8dfbf380 | 600 | { |
601 | basic_block *body = get_loop_body_in_dom_order (loop); | |
602 | basic_block bb; | |
603 | unsigned i; | |
75a70cf9 | 604 | gimple_stmt_iterator bsi; |
605 | gimple stmt; | |
606 | tree lhs, rhs; | |
8dfbf380 | 607 | struct mem_ref_group *refs = NULL; |
608 | ||
5b5037b3 | 609 | *no_other_refs = true; |
0ab353e1 | 610 | *ref_count = 0; |
5b5037b3 | 611 | |
8dfbf380 | 612 | /* Scan the loop body in order, so that the former references precede the |
613 | later ones. */ | |
614 | for (i = 0; i < loop->num_nodes; i++) | |
615 | { | |
616 | bb = body[i]; | |
617 | if (bb->loop_father != loop) | |
618 | continue; | |
619 | ||
75a70cf9 | 620 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
8dfbf380 | 621 | { |
75a70cf9 | 622 | stmt = gsi_stmt (bsi); |
5b5037b3 | 623 | |
75a70cf9 | 624 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
5b5037b3 | 625 | { |
dd277d48 | 626 | if (gimple_vuse (stmt) |
75a70cf9 | 627 | || (is_gimple_call (stmt) |
628 | && !(gimple_call_flags (stmt) & ECF_CONST))) | |
5b5037b3 | 629 | *no_other_refs = false; |
630 | continue; | |
631 | } | |
8dfbf380 | 632 | |
75a70cf9 | 633 | lhs = gimple_assign_lhs (stmt); |
634 | rhs = gimple_assign_rhs1 (stmt); | |
8dfbf380 | 635 | |
636 | if (REFERENCE_CLASS_P (rhs)) | |
0ab353e1 | 637 | { |
5b5037b3 | 638 | *no_other_refs &= gather_memory_references_ref (loop, &refs, |
639 | rhs, false, stmt); | |
0ab353e1 | 640 | *ref_count += 1; |
641 | } | |
8dfbf380 | 642 | if (REFERENCE_CLASS_P (lhs)) |
0ab353e1 | 643 | { |
5b5037b3 | 644 | *no_other_refs &= gather_memory_references_ref (loop, &refs, |
645 | lhs, true, stmt); | |
0ab353e1 | 646 | *ref_count += 1; |
647 | } | |
8dfbf380 | 648 | } |
649 | } | |
650 | free (body); | |
651 | ||
652 | return refs; | |
653 | } | |
654 | ||
655 | /* Prune the prefetch candidate REF using the self-reuse. */ | |
656 | ||
657 | static void | |
658 | prune_ref_by_self_reuse (struct mem_ref *ref) | |
659 | { | |
81d2a38f | 660 | HOST_WIDE_INT step; |
661 | bool backward; | |
662 | ||
663 | /* If the step size is non constant, we cannot calculate prefetch_mod. */ | |
664 | if (!cst_and_fits_in_hwi (ref->group->step)) | |
665 | return; | |
666 | ||
667 | step = int_cst_value (ref->group->step); | |
668 | ||
669 | backward = step < 0; | |
8dfbf380 | 670 | |
671 | if (step == 0) | |
672 | { | |
673 | /* Prefetch references to invariant address just once. */ | |
674 | ref->prefetch_before = 1; | |
675 | return; | |
676 | } | |
677 | ||
678 | if (backward) | |
679 | step = -step; | |
680 | ||
681 | if (step > PREFETCH_BLOCK) | |
682 | return; | |
683 | ||
684 | if ((backward && HAVE_BACKWARD_PREFETCH) | |
685 | || (!backward && HAVE_FORWARD_PREFETCH)) | |
686 | { | |
687 | ref->prefetch_before = 1; | |
688 | return; | |
689 | } | |
690 | ||
691 | ref->prefetch_mod = PREFETCH_BLOCK / step; | |
692 | } | |
693 | ||
694 | /* Divides X by BY, rounding down. */ | |
695 | ||
696 | static HOST_WIDE_INT | |
697 | ddown (HOST_WIDE_INT x, unsigned HOST_WIDE_INT by) | |
698 | { | |
699 | gcc_assert (by > 0); | |
700 | ||
701 | if (x >= 0) | |
702 | return x / by; | |
703 | else | |
704 | return (x + by - 1) / by; | |
705 | } | |
706 | ||
48e1416a | 707 | /* Given a CACHE_LINE_SIZE and two inductive memory references |
708 | with a common STEP greater than CACHE_LINE_SIZE and an address | |
709 | difference DELTA, compute the probability that they will fall | |
3a2f43cf | 710 | in different cache lines. Return true if the computed miss rate |
711 | is not greater than the ACCEPTABLE_MISS_RATE. DISTINCT_ITERS is the | |
712 | number of distinct iterations after which the pattern repeats itself. | |
e17cf2c8 | 713 | ALIGN_UNIT is the unit of alignment in bytes. */ |
714 | ||
3a2f43cf | 715 | static bool |
716 | is_miss_rate_acceptable (unsigned HOST_WIDE_INT cache_line_size, | |
e17cf2c8 | 717 | HOST_WIDE_INT step, HOST_WIDE_INT delta, |
718 | unsigned HOST_WIDE_INT distinct_iters, | |
719 | int align_unit) | |
720 | { | |
721 | unsigned align, iter; | |
3a2f43cf | 722 | int total_positions, miss_positions, max_allowed_miss_positions; |
e17cf2c8 | 723 | int address1, address2, cache_line1, cache_line2; |
724 | ||
5a91155f | 725 | /* It always misses if delta is greater than or equal to the cache |
726 | line size. */ | |
3a2f43cf | 727 | if (delta >= (HOST_WIDE_INT) cache_line_size) |
728 | return false; | |
5a91155f | 729 | |
e17cf2c8 | 730 | miss_positions = 0; |
3a2f43cf | 731 | total_positions = (cache_line_size / align_unit) * distinct_iters; |
732 | max_allowed_miss_positions = (ACCEPTABLE_MISS_RATE * total_positions) / 1000; | |
48e1416a | 733 | |
e17cf2c8 | 734 | /* Iterate through all possible alignments of the first |
735 | memory reference within its cache line. */ | |
736 | for (align = 0; align < cache_line_size; align += align_unit) | |
737 | ||
738 | /* Iterate through all distinct iterations. */ | |
739 | for (iter = 0; iter < distinct_iters; iter++) | |
740 | { | |
741 | address1 = align + step * iter; | |
742 | address2 = address1 + delta; | |
743 | cache_line1 = address1 / cache_line_size; | |
744 | cache_line2 = address2 / cache_line_size; | |
e17cf2c8 | 745 | if (cache_line1 != cache_line2) |
3a2f43cf | 746 | { |
747 | miss_positions += 1; | |
748 | if (miss_positions > max_allowed_miss_positions) | |
749 | return false; | |
750 | } | |
e17cf2c8 | 751 | } |
3a2f43cf | 752 | return true; |
e17cf2c8 | 753 | } |
754 | ||
8dfbf380 | 755 | /* Prune the prefetch candidate REF using the reuse with BY. |
756 | If BY_IS_BEFORE is true, BY is before REF in the loop. */ | |
757 | ||
758 | static void | |
759 | prune_ref_by_group_reuse (struct mem_ref *ref, struct mem_ref *by, | |
760 | bool by_is_before) | |
761 | { | |
81d2a38f | 762 | HOST_WIDE_INT step; |
763 | bool backward; | |
8dfbf380 | 764 | HOST_WIDE_INT delta_r = ref->delta, delta_b = by->delta; |
765 | HOST_WIDE_INT delta = delta_b - delta_r; | |
766 | HOST_WIDE_INT hit_from; | |
767 | unsigned HOST_WIDE_INT prefetch_before, prefetch_block; | |
e17cf2c8 | 768 | HOST_WIDE_INT reduced_step; |
769 | unsigned HOST_WIDE_INT reduced_prefetch_block; | |
770 | tree ref_type; | |
771 | int align_unit; | |
8dfbf380 | 772 | |
81d2a38f | 773 | /* If the step is non constant we cannot calculate prefetch_before. */ |
774 | if (!cst_and_fits_in_hwi (ref->group->step)) { | |
775 | return; | |
776 | } | |
777 | ||
778 | step = int_cst_value (ref->group->step); | |
779 | ||
780 | backward = step < 0; | |
781 | ||
782 | ||
8dfbf380 | 783 | if (delta == 0) |
784 | { | |
785 | /* If the references has the same address, only prefetch the | |
786 | former. */ | |
787 | if (by_is_before) | |
788 | ref->prefetch_before = 0; | |
48e1416a | 789 | |
8dfbf380 | 790 | return; |
791 | } | |
792 | ||
793 | if (!step) | |
794 | { | |
795 | /* If the reference addresses are invariant and fall into the | |
796 | same cache line, prefetch just the first one. */ | |
797 | if (!by_is_before) | |
798 | return; | |
799 | ||
800 | if (ddown (ref->delta, PREFETCH_BLOCK) | |
801 | != ddown (by->delta, PREFETCH_BLOCK)) | |
802 | return; | |
803 | ||
804 | ref->prefetch_before = 0; | |
805 | return; | |
806 | } | |
807 | ||
808 | /* Only prune the reference that is behind in the array. */ | |
809 | if (backward) | |
810 | { | |
811 | if (delta > 0) | |
812 | return; | |
813 | ||
814 | /* Transform the data so that we may assume that the accesses | |
815 | are forward. */ | |
816 | delta = - delta; | |
817 | step = -step; | |
818 | delta_r = PREFETCH_BLOCK - 1 - delta_r; | |
819 | delta_b = PREFETCH_BLOCK - 1 - delta_b; | |
820 | } | |
821 | else | |
822 | { | |
823 | if (delta < 0) | |
824 | return; | |
825 | } | |
826 | ||
827 | /* Check whether the two references are likely to hit the same cache | |
828 | line, and how distant the iterations in that it occurs are from | |
829 | each other. */ | |
830 | ||
831 | if (step <= PREFETCH_BLOCK) | |
832 | { | |
833 | /* The accesses are sure to meet. Let us check when. */ | |
834 | hit_from = ddown (delta_b, PREFETCH_BLOCK) * PREFETCH_BLOCK; | |
835 | prefetch_before = (hit_from - delta_r + step - 1) / step; | |
836 | ||
8234f090 | 837 | /* Do not reduce prefetch_before if we meet beyond cache size. */ |
b1757d46 | 838 | if (prefetch_before > absu_hwi (L2_CACHE_SIZE_BYTES / step)) |
8234f090 | 839 | prefetch_before = PREFETCH_ALL; |
8dfbf380 | 840 | if (prefetch_before < ref->prefetch_before) |
841 | ref->prefetch_before = prefetch_before; | |
842 | ||
843 | return; | |
844 | } | |
845 | ||
48e1416a | 846 | /* A more complicated case with step > prefetch_block. First reduce |
e17cf2c8 | 847 | the ratio between the step and the cache line size to its simplest |
48e1416a | 848 | terms. The resulting denominator will then represent the number of |
849 | distinct iterations after which each address will go back to its | |
850 | initial location within the cache line. This computation assumes | |
e17cf2c8 | 851 | that PREFETCH_BLOCK is a power of two. */ |
8dfbf380 | 852 | prefetch_block = PREFETCH_BLOCK; |
e17cf2c8 | 853 | reduced_prefetch_block = prefetch_block; |
854 | reduced_step = step; | |
855 | while ((reduced_step & 1) == 0 | |
856 | && reduced_prefetch_block > 1) | |
8dfbf380 | 857 | { |
e17cf2c8 | 858 | reduced_step >>= 1; |
859 | reduced_prefetch_block >>= 1; | |
8dfbf380 | 860 | } |
861 | ||
8dfbf380 | 862 | prefetch_before = delta / step; |
863 | delta %= step; | |
e17cf2c8 | 864 | ref_type = TREE_TYPE (ref->mem); |
865 | align_unit = TYPE_ALIGN (ref_type) / 8; | |
3a2f43cf | 866 | if (is_miss_rate_acceptable (prefetch_block, step, delta, |
867 | reduced_prefetch_block, align_unit)) | |
8dfbf380 | 868 | { |
8234f090 | 869 | /* Do not reduce prefetch_before if we meet beyond cache size. */ |
870 | if (prefetch_before > L2_CACHE_SIZE_BYTES / PREFETCH_BLOCK) | |
871 | prefetch_before = PREFETCH_ALL; | |
8dfbf380 | 872 | if (prefetch_before < ref->prefetch_before) |
873 | ref->prefetch_before = prefetch_before; | |
874 | ||
875 | return; | |
876 | } | |
877 | ||
878 | /* Try also the following iteration. */ | |
879 | prefetch_before++; | |
880 | delta = step - delta; | |
3a2f43cf | 881 | if (is_miss_rate_acceptable (prefetch_block, step, delta, |
882 | reduced_prefetch_block, align_unit)) | |
8dfbf380 | 883 | { |
884 | if (prefetch_before < ref->prefetch_before) | |
885 | ref->prefetch_before = prefetch_before; | |
886 | ||
887 | return; | |
888 | } | |
889 | ||
890 | /* The ref probably does not reuse by. */ | |
891 | return; | |
892 | } | |
893 | ||
894 | /* Prune the prefetch candidate REF using the reuses with other references | |
895 | in REFS. */ | |
896 | ||
897 | static void | |
898 | prune_ref_by_reuse (struct mem_ref *ref, struct mem_ref *refs) | |
899 | { | |
900 | struct mem_ref *prune_by; | |
901 | bool before = true; | |
902 | ||
903 | prune_ref_by_self_reuse (ref); | |
904 | ||
905 | for (prune_by = refs; prune_by; prune_by = prune_by->next) | |
906 | { | |
907 | if (prune_by == ref) | |
908 | { | |
909 | before = false; | |
910 | continue; | |
911 | } | |
912 | ||
913 | if (!WRITE_CAN_USE_READ_PREFETCH | |
914 | && ref->write_p | |
915 | && !prune_by->write_p) | |
916 | continue; | |
917 | if (!READ_CAN_USE_WRITE_PREFETCH | |
918 | && !ref->write_p | |
919 | && prune_by->write_p) | |
920 | continue; | |
921 | ||
922 | prune_ref_by_group_reuse (ref, prune_by, before); | |
923 | } | |
924 | } | |
925 | ||
926 | /* Prune the prefetch candidates in GROUP using the reuse analysis. */ | |
927 | ||
928 | static void | |
929 | prune_group_by_reuse (struct mem_ref_group *group) | |
930 | { | |
931 | struct mem_ref *ref_pruned; | |
932 | ||
933 | for (ref_pruned = group->refs; ref_pruned; ref_pruned = ref_pruned->next) | |
934 | { | |
935 | prune_ref_by_reuse (ref_pruned, group->refs); | |
936 | ||
937 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
938 | { | |
939 | fprintf (dump_file, "Reference %p:", (void *) ref_pruned); | |
940 | ||
941 | if (ref_pruned->prefetch_before == PREFETCH_ALL | |
942 | && ref_pruned->prefetch_mod == 1) | |
943 | fprintf (dump_file, " no restrictions"); | |
944 | else if (ref_pruned->prefetch_before == 0) | |
945 | fprintf (dump_file, " do not prefetch"); | |
946 | else if (ref_pruned->prefetch_before <= ref_pruned->prefetch_mod) | |
947 | fprintf (dump_file, " prefetch once"); | |
948 | else | |
949 | { | |
950 | if (ref_pruned->prefetch_before != PREFETCH_ALL) | |
951 | { | |
952 | fprintf (dump_file, " prefetch before "); | |
953 | fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, | |
954 | ref_pruned->prefetch_before); | |
955 | } | |
956 | if (ref_pruned->prefetch_mod != 1) | |
957 | { | |
958 | fprintf (dump_file, " prefetch mod "); | |
959 | fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, | |
960 | ref_pruned->prefetch_mod); | |
961 | } | |
962 | } | |
963 | fprintf (dump_file, "\n"); | |
964 | } | |
965 | } | |
966 | } | |
967 | ||
968 | /* Prune the list of prefetch candidates GROUPS using the reuse analysis. */ | |
969 | ||
970 | static void | |
971 | prune_by_reuse (struct mem_ref_group *groups) | |
972 | { | |
973 | for (; groups; groups = groups->next) | |
974 | prune_group_by_reuse (groups); | |
975 | } | |
976 | ||
977 | /* Returns true if we should issue prefetch for REF. */ | |
978 | ||
979 | static bool | |
980 | should_issue_prefetch_p (struct mem_ref *ref) | |
981 | { | |
982 | /* For now do not issue prefetches for only first few of the | |
983 | iterations. */ | |
984 | if (ref->prefetch_before != PREFETCH_ALL) | |
5d68c00f | 985 | { |
986 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
987 | fprintf (dump_file, "Ignoring %p due to prefetch_before\n", | |
988 | (void *) ref); | |
989 | return false; | |
990 | } | |
8dfbf380 | 991 | |
5b5037b3 | 992 | /* Do not prefetch nontemporal stores. */ |
993 | if (ref->storent_p) | |
5d68c00f | 994 | { |
995 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
996 | fprintf (dump_file, "Ignoring nontemporal store %p\n", (void *) ref); | |
997 | return false; | |
998 | } | |
5b5037b3 | 999 | |
8dfbf380 | 1000 | return true; |
1001 | } | |
1002 | ||
1003 | /* Decide which of the prefetch candidates in GROUPS to prefetch. | |
1004 | AHEAD is the number of iterations to prefetch ahead (which corresponds | |
1005 | to the number of simultaneous instances of one prefetch running at a | |
1006 | time). UNROLL_FACTOR is the factor by that the loop is going to be | |
1007 | unrolled. Returns true if there is anything to prefetch. */ | |
1008 | ||
1009 | static bool | |
1010 | schedule_prefetches (struct mem_ref_group *groups, unsigned unroll_factor, | |
1011 | unsigned ahead) | |
1012 | { | |
53d4d5cc | 1013 | unsigned remaining_prefetch_slots, n_prefetches, prefetch_slots; |
1014 | unsigned slots_per_prefetch; | |
8dfbf380 | 1015 | struct mem_ref *ref; |
1016 | bool any = false; | |
1017 | ||
53d4d5cc | 1018 | /* At most SIMULTANEOUS_PREFETCHES should be running at the same time. */ |
1019 | remaining_prefetch_slots = SIMULTANEOUS_PREFETCHES; | |
8dfbf380 | 1020 | |
53d4d5cc | 1021 | /* The prefetch will run for AHEAD iterations of the original loop, i.e., |
1022 | AHEAD / UNROLL_FACTOR iterations of the unrolled loop. In each iteration, | |
1023 | it will need a prefetch slot. */ | |
1024 | slots_per_prefetch = (ahead + unroll_factor / 2) / unroll_factor; | |
8dfbf380 | 1025 | if (dump_file && (dump_flags & TDF_DETAILS)) |
53d4d5cc | 1026 | fprintf (dump_file, "Each prefetch instruction takes %u prefetch slots.\n", |
1027 | slots_per_prefetch); | |
8dfbf380 | 1028 | |
1029 | /* For now we just take memory references one by one and issue | |
1030 | prefetches for as many as possible. The groups are sorted | |
1031 | starting with the largest step, since the references with | |
334ec2d8 | 1032 | large step are more likely to cause many cache misses. */ |
8dfbf380 | 1033 | |
1034 | for (; groups; groups = groups->next) | |
1035 | for (ref = groups->refs; ref; ref = ref->next) | |
1036 | { | |
1037 | if (!should_issue_prefetch_p (ref)) | |
1038 | continue; | |
1039 | ||
c0a0de5e | 1040 | /* The loop is far from being sufficiently unrolled for this |
1041 | prefetch. Do not generate prefetch to avoid many redudant | |
1042 | prefetches. */ | |
1043 | if (ref->prefetch_mod / unroll_factor > PREFETCH_MOD_TO_UNROLL_FACTOR_RATIO) | |
1044 | continue; | |
1045 | ||
53d4d5cc | 1046 | /* If we need to prefetch the reference each PREFETCH_MOD iterations, |
1047 | and we unroll the loop UNROLL_FACTOR times, we need to insert | |
1048 | ceil (UNROLL_FACTOR / PREFETCH_MOD) instructions in each | |
1049 | iteration. */ | |
8dfbf380 | 1050 | n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) |
1051 | / ref->prefetch_mod); | |
53d4d5cc | 1052 | prefetch_slots = n_prefetches * slots_per_prefetch; |
1053 | ||
1054 | /* If more than half of the prefetches would be lost anyway, do not | |
1055 | issue the prefetch. */ | |
1056 | if (2 * remaining_prefetch_slots < prefetch_slots) | |
1057 | continue; | |
1058 | ||
1059 | ref->issue_prefetch_p = true; | |
8dfbf380 | 1060 | |
53d4d5cc | 1061 | if (remaining_prefetch_slots <= prefetch_slots) |
1062 | return true; | |
1063 | remaining_prefetch_slots -= prefetch_slots; | |
8dfbf380 | 1064 | any = true; |
1065 | } | |
1066 | ||
1067 | return any; | |
1068 | } | |
1069 | ||
5da8318c | 1070 | /* Return TRUE if no prefetch is going to be generated in the given |
1071 | GROUPS. */ | |
1072 | ||
1073 | static bool | |
1074 | nothing_to_prefetch_p (struct mem_ref_group *groups) | |
1075 | { | |
1076 | struct mem_ref *ref; | |
1077 | ||
1078 | for (; groups; groups = groups->next) | |
1079 | for (ref = groups->refs; ref; ref = ref->next) | |
1080 | if (should_issue_prefetch_p (ref)) | |
1081 | return false; | |
1082 | ||
1083 | return true; | |
1084 | } | |
1085 | ||
1086 | /* Estimate the number of prefetches in the given GROUPS. | |
1087 | UNROLL_FACTOR is the factor by which LOOP was unrolled. */ | |
8dfbf380 | 1088 | |
0ab353e1 | 1089 | static int |
5da8318c | 1090 | estimate_prefetch_count (struct mem_ref_group *groups, unsigned unroll_factor) |
8dfbf380 | 1091 | { |
1092 | struct mem_ref *ref; | |
5da8318c | 1093 | unsigned n_prefetches; |
0ab353e1 | 1094 | int prefetch_count = 0; |
8dfbf380 | 1095 | |
1096 | for (; groups; groups = groups->next) | |
1097 | for (ref = groups->refs; ref; ref = ref->next) | |
1098 | if (should_issue_prefetch_p (ref)) | |
5da8318c | 1099 | { |
1100 | n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) | |
1101 | / ref->prefetch_mod); | |
1102 | prefetch_count += n_prefetches; | |
1103 | } | |
8dfbf380 | 1104 | |
0ab353e1 | 1105 | return prefetch_count; |
8dfbf380 | 1106 | } |
1107 | ||
1108 | /* Issue prefetches for the reference REF into loop as decided before. | |
1109 | HEAD is the number of iterations to prefetch ahead. UNROLL_FACTOR | |
9ca2c29a | 1110 | is the factor by which LOOP was unrolled. */ |
8dfbf380 | 1111 | |
1112 | static void | |
1113 | issue_prefetch_ref (struct mem_ref *ref, unsigned unroll_factor, unsigned ahead) | |
1114 | { | |
1115 | HOST_WIDE_INT delta; | |
81d2a38f | 1116 | tree addr, addr_base, write_p, local, forward; |
75a70cf9 | 1117 | gimple prefetch; |
1118 | gimple_stmt_iterator bsi; | |
8dfbf380 | 1119 | unsigned n_prefetches, ap; |
5c205353 | 1120 | bool nontemporal = ref->reuse_distance >= L2_CACHE_SIZE_BYTES; |
8dfbf380 | 1121 | |
1122 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
5c205353 | 1123 | fprintf (dump_file, "Issued%s prefetch for %p.\n", |
1124 | nontemporal ? " nontemporal" : "", | |
1125 | (void *) ref); | |
8dfbf380 | 1126 | |
75a70cf9 | 1127 | bsi = gsi_for_stmt (ref->stmt); |
8dfbf380 | 1128 | |
1129 | n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) | |
1130 | / ref->prefetch_mod); | |
1131 | addr_base = build_fold_addr_expr_with_type (ref->mem, ptr_type_node); | |
75a70cf9 | 1132 | addr_base = force_gimple_operand_gsi (&bsi, unshare_expr (addr_base), |
1133 | true, NULL, true, GSI_SAME_STMT); | |
53d4d5cc | 1134 | write_p = ref->write_p ? integer_one_node : integer_zero_node; |
2512209b | 1135 | local = nontemporal ? integer_zero_node : integer_three_node; |
8dfbf380 | 1136 | |
1137 | for (ap = 0; ap < n_prefetches; ap++) | |
1138 | { | |
81d2a38f | 1139 | if (cst_and_fits_in_hwi (ref->group->step)) |
1140 | { | |
1141 | /* Determine the address to prefetch. */ | |
1142 | delta = (ahead + ap * ref->prefetch_mod) * | |
1143 | int_cst_value (ref->group->step); | |
2cc66f2a | 1144 | addr = fold_build_pointer_plus_hwi (addr_base, delta); |
81d2a38f | 1145 | addr = force_gimple_operand_gsi (&bsi, unshare_expr (addr), true, NULL, |
1146 | true, GSI_SAME_STMT); | |
1147 | } | |
1148 | else | |
1149 | { | |
1150 | /* The step size is non-constant but loop-invariant. We use the | |
1151 | heuristic to simply prefetch ahead iterations ahead. */ | |
1152 | forward = fold_build2 (MULT_EXPR, sizetype, | |
1153 | fold_convert (sizetype, ref->group->step), | |
1154 | fold_convert (sizetype, size_int (ahead))); | |
2cc66f2a | 1155 | addr = fold_build_pointer_plus (addr_base, forward); |
81d2a38f | 1156 | addr = force_gimple_operand_gsi (&bsi, unshare_expr (addr), true, |
1157 | NULL, true, GSI_SAME_STMT); | |
1158 | } | |
8dfbf380 | 1159 | /* Create the prefetch instruction. */ |
b9a16870 | 1160 | prefetch = gimple_build_call (builtin_decl_explicit (BUILT_IN_PREFETCH), |
75a70cf9 | 1161 | 3, addr, write_p, local); |
1162 | gsi_insert_before (&bsi, prefetch, GSI_SAME_STMT); | |
8dfbf380 | 1163 | } |
1164 | } | |
1165 | ||
1166 | /* Issue prefetches for the references in GROUPS into loop as decided before. | |
1167 | HEAD is the number of iterations to prefetch ahead. UNROLL_FACTOR is the | |
1168 | factor by that LOOP was unrolled. */ | |
1169 | ||
1170 | static void | |
1171 | issue_prefetches (struct mem_ref_group *groups, | |
1172 | unsigned unroll_factor, unsigned ahead) | |
1173 | { | |
1174 | struct mem_ref *ref; | |
1175 | ||
1176 | for (; groups; groups = groups->next) | |
1177 | for (ref = groups->refs; ref; ref = ref->next) | |
1178 | if (ref->issue_prefetch_p) | |
1179 | issue_prefetch_ref (ref, unroll_factor, ahead); | |
1180 | } | |
1181 | ||
5b5037b3 | 1182 | /* Returns true if REF is a memory write for that a nontemporal store insn |
1183 | can be used. */ | |
1184 | ||
1185 | static bool | |
1186 | nontemporal_store_p (struct mem_ref *ref) | |
1187 | { | |
1188 | enum machine_mode mode; | |
1189 | enum insn_code code; | |
1190 | ||
1191 | /* REF must be a write that is not reused. We require it to be independent | |
1192 | on all other memory references in the loop, as the nontemporal stores may | |
1193 | be reordered with respect to other memory references. */ | |
1194 | if (!ref->write_p | |
1195 | || !ref->independent_p | |
1196 | || ref->reuse_distance < L2_CACHE_SIZE_BYTES) | |
1197 | return false; | |
1198 | ||
1199 | /* Check that we have the storent instruction for the mode. */ | |
1200 | mode = TYPE_MODE (TREE_TYPE (ref->mem)); | |
1201 | if (mode == BLKmode) | |
1202 | return false; | |
1203 | ||
d6bf3b14 | 1204 | code = optab_handler (storent_optab, mode); |
5b5037b3 | 1205 | return code != CODE_FOR_nothing; |
1206 | } | |
1207 | ||
1208 | /* If REF is a nontemporal store, we mark the corresponding modify statement | |
1209 | and return true. Otherwise, we return false. */ | |
1210 | ||
1211 | static bool | |
1212 | mark_nontemporal_store (struct mem_ref *ref) | |
1213 | { | |
1214 | if (!nontemporal_store_p (ref)) | |
1215 | return false; | |
1216 | ||
1217 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1218 | fprintf (dump_file, "Marked reference %p as a nontemporal store.\n", | |
1219 | (void *) ref); | |
1220 | ||
75a70cf9 | 1221 | gimple_assign_set_nontemporal_move (ref->stmt, true); |
5b5037b3 | 1222 | ref->storent_p = true; |
1223 | ||
1224 | return true; | |
1225 | } | |
1226 | ||
1227 | /* Issue a memory fence instruction after LOOP. */ | |
1228 | ||
1229 | static void | |
1230 | emit_mfence_after_loop (struct loop *loop) | |
1231 | { | |
f1f41a6c | 1232 | vec<edge> exits = get_loop_exit_edges (loop); |
5b5037b3 | 1233 | edge exit; |
75a70cf9 | 1234 | gimple call; |
1235 | gimple_stmt_iterator bsi; | |
5b5037b3 | 1236 | unsigned i; |
1237 | ||
f1f41a6c | 1238 | FOR_EACH_VEC_ELT (exits, i, exit) |
5b5037b3 | 1239 | { |
75a70cf9 | 1240 | call = gimple_build_call (FENCE_FOLLOWING_MOVNT, 0); |
5b5037b3 | 1241 | |
1242 | if (!single_pred_p (exit->dest) | |
1243 | /* If possible, we prefer not to insert the fence on other paths | |
1244 | in cfg. */ | |
1245 | && !(exit->flags & EDGE_ABNORMAL)) | |
1246 | split_loop_exit_edge (exit); | |
75a70cf9 | 1247 | bsi = gsi_after_labels (exit->dest); |
5b5037b3 | 1248 | |
75a70cf9 | 1249 | gsi_insert_before (&bsi, call, GSI_NEW_STMT); |
5b5037b3 | 1250 | } |
1251 | ||
f1f41a6c | 1252 | exits.release (); |
5b5037b3 | 1253 | update_ssa (TODO_update_ssa_only_virtuals); |
1254 | } | |
1255 | ||
1256 | /* Returns true if we can use storent in loop, false otherwise. */ | |
1257 | ||
1258 | static bool | |
1259 | may_use_storent_in_loop_p (struct loop *loop) | |
1260 | { | |
1261 | bool ret = true; | |
1262 | ||
1263 | if (loop->inner != NULL) | |
1264 | return false; | |
1265 | ||
1266 | /* If we must issue a mfence insn after using storent, check that there | |
1267 | is a suitable place for it at each of the loop exits. */ | |
1268 | if (FENCE_FOLLOWING_MOVNT != NULL_TREE) | |
1269 | { | |
f1f41a6c | 1270 | vec<edge> exits = get_loop_exit_edges (loop); |
5b5037b3 | 1271 | unsigned i; |
1272 | edge exit; | |
1273 | ||
f1f41a6c | 1274 | FOR_EACH_VEC_ELT (exits, i, exit) |
5b5037b3 | 1275 | if ((exit->flags & EDGE_ABNORMAL) |
1276 | && exit->dest == EXIT_BLOCK_PTR) | |
1277 | ret = false; | |
1278 | ||
f1f41a6c | 1279 | exits.release (); |
5b5037b3 | 1280 | } |
1281 | ||
1282 | return ret; | |
1283 | } | |
1284 | ||
1285 | /* Marks nontemporal stores in LOOP. GROUPS contains the description of memory | |
1286 | references in the loop. */ | |
1287 | ||
1288 | static void | |
1289 | mark_nontemporal_stores (struct loop *loop, struct mem_ref_group *groups) | |
1290 | { | |
1291 | struct mem_ref *ref; | |
1292 | bool any = false; | |
1293 | ||
1294 | if (!may_use_storent_in_loop_p (loop)) | |
1295 | return; | |
1296 | ||
1297 | for (; groups; groups = groups->next) | |
1298 | for (ref = groups->refs; ref; ref = ref->next) | |
1299 | any |= mark_nontemporal_store (ref); | |
1300 | ||
1301 | if (any && FENCE_FOLLOWING_MOVNT != NULL_TREE) | |
1302 | emit_mfence_after_loop (loop); | |
1303 | } | |
1304 | ||
8dfbf380 | 1305 | /* Determines whether we can profitably unroll LOOP FACTOR times, and if |
1306 | this is the case, fill in DESC by the description of number of | |
1307 | iterations. */ | |
1308 | ||
1309 | static bool | |
1310 | should_unroll_loop_p (struct loop *loop, struct tree_niter_desc *desc, | |
1311 | unsigned factor) | |
1312 | { | |
1313 | if (!can_unroll_loop_p (loop, factor, desc)) | |
1314 | return false; | |
1315 | ||
1316 | /* We only consider loops without control flow for unrolling. This is not | |
1317 | a hard restriction -- tree_unroll_loop works with arbitrary loops | |
1318 | as well; but the unrolling/prefetching is usually more profitable for | |
1319 | loops consisting of a single basic block, and we want to limit the | |
1320 | code growth. */ | |
1321 | if (loop->num_nodes > 2) | |
1322 | return false; | |
1323 | ||
1324 | return true; | |
1325 | } | |
1326 | ||
1327 | /* Determine the coefficient by that unroll LOOP, from the information | |
1328 | contained in the list of memory references REFS. Description of | |
78f46d45 | 1329 | umber of iterations of LOOP is stored to DESC. NINSNS is the number of |
1330 | insns of the LOOP. EST_NITER is the estimated number of iterations of | |
1331 | the loop, or -1 if no estimate is available. */ | |
8dfbf380 | 1332 | |
1333 | static unsigned | |
1334 | determine_unroll_factor (struct loop *loop, struct mem_ref_group *refs, | |
78f46d45 | 1335 | unsigned ninsns, struct tree_niter_desc *desc, |
1336 | HOST_WIDE_INT est_niter) | |
8dfbf380 | 1337 | { |
53d4d5cc | 1338 | unsigned upper_bound; |
1339 | unsigned nfactor, factor, mod_constraint; | |
8dfbf380 | 1340 | struct mem_ref_group *agp; |
1341 | struct mem_ref *ref; | |
1342 | ||
53d4d5cc | 1343 | /* First check whether the loop is not too large to unroll. We ignore |
1344 | PARAM_MAX_UNROLL_TIMES, because for small loops, it prevented us | |
1345 | from unrolling them enough to make exactly one cache line covered by each | |
1346 | iteration. Also, the goal of PARAM_MAX_UNROLL_TIMES is to prevent | |
1347 | us from unrolling the loops too many times in cases where we only expect | |
1348 | gains from better scheduling and decreasing loop overhead, which is not | |
1349 | the case here. */ | |
1350 | upper_bound = PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS) / ninsns; | |
78f46d45 | 1351 | |
1352 | /* If we unrolled the loop more times than it iterates, the unrolled version | |
1353 | of the loop would be never entered. */ | |
1354 | if (est_niter >= 0 && est_niter < (HOST_WIDE_INT) upper_bound) | |
1355 | upper_bound = est_niter; | |
1356 | ||
53d4d5cc | 1357 | if (upper_bound <= 1) |
8dfbf380 | 1358 | return 1; |
1359 | ||
53d4d5cc | 1360 | /* Choose the factor so that we may prefetch each cache just once, |
1361 | but bound the unrolling by UPPER_BOUND. */ | |
1362 | factor = 1; | |
8dfbf380 | 1363 | for (agp = refs; agp; agp = agp->next) |
1364 | for (ref = agp->refs; ref; ref = ref->next) | |
53d4d5cc | 1365 | if (should_issue_prefetch_p (ref)) |
1366 | { | |
1367 | mod_constraint = ref->prefetch_mod; | |
1368 | nfactor = least_common_multiple (mod_constraint, factor); | |
1369 | if (nfactor <= upper_bound) | |
1370 | factor = nfactor; | |
1371 | } | |
8dfbf380 | 1372 | |
1373 | if (!should_unroll_loop_p (loop, desc, factor)) | |
1374 | return 1; | |
1375 | ||
1376 | return factor; | |
1377 | } | |
1378 | ||
5c205353 | 1379 | /* Returns the total volume of the memory references REFS, taking into account |
1380 | reuses in the innermost loop and cache line size. TODO -- we should also | |
1381 | take into account reuses across the iterations of the loops in the loop | |
1382 | nest. */ | |
1383 | ||
1384 | static unsigned | |
1385 | volume_of_references (struct mem_ref_group *refs) | |
1386 | { | |
1387 | unsigned volume = 0; | |
1388 | struct mem_ref_group *gr; | |
1389 | struct mem_ref *ref; | |
1390 | ||
1391 | for (gr = refs; gr; gr = gr->next) | |
1392 | for (ref = gr->refs; ref; ref = ref->next) | |
1393 | { | |
1394 | /* Almost always reuses another value? */ | |
1395 | if (ref->prefetch_before != PREFETCH_ALL) | |
1396 | continue; | |
1397 | ||
1398 | /* If several iterations access the same cache line, use the size of | |
1399 | the line divided by this number. Otherwise, a cache line is | |
1400 | accessed in each iteration. TODO -- in the latter case, we should | |
1401 | take the size of the reference into account, rounding it up on cache | |
1402 | line size multiple. */ | |
1403 | volume += L1_CACHE_LINE_SIZE / ref->prefetch_mod; | |
1404 | } | |
1405 | return volume; | |
1406 | } | |
1407 | ||
1408 | /* Returns the volume of memory references accessed across VEC iterations of | |
1409 | loops, whose sizes are described in the LOOP_SIZES array. N is the number | |
1410 | of the loops in the nest (length of VEC and LOOP_SIZES vectors). */ | |
1411 | ||
1412 | static unsigned | |
1413 | volume_of_dist_vector (lambda_vector vec, unsigned *loop_sizes, unsigned n) | |
1414 | { | |
1415 | unsigned i; | |
1416 | ||
1417 | for (i = 0; i < n; i++) | |
1418 | if (vec[i] != 0) | |
1419 | break; | |
1420 | ||
1421 | if (i == n) | |
1422 | return 0; | |
1423 | ||
1424 | gcc_assert (vec[i] > 0); | |
1425 | ||
1426 | /* We ignore the parts of the distance vector in subloops, since usually | |
1427 | the numbers of iterations are much smaller. */ | |
1428 | return loop_sizes[i] * vec[i]; | |
1429 | } | |
1430 | ||
1431 | /* Add the steps of ACCESS_FN multiplied by STRIDE to the array STRIDE | |
1432 | at the position corresponding to the loop of the step. N is the depth | |
1433 | of the considered loop nest, and, LOOP is its innermost loop. */ | |
1434 | ||
1435 | static void | |
1436 | add_subscript_strides (tree access_fn, unsigned stride, | |
1437 | HOST_WIDE_INT *strides, unsigned n, struct loop *loop) | |
1438 | { | |
1439 | struct loop *aloop; | |
1440 | tree step; | |
1441 | HOST_WIDE_INT astep; | |
1442 | unsigned min_depth = loop_depth (loop) - n; | |
1443 | ||
1444 | while (TREE_CODE (access_fn) == POLYNOMIAL_CHREC) | |
1445 | { | |
1446 | aloop = get_chrec_loop (access_fn); | |
1447 | step = CHREC_RIGHT (access_fn); | |
1448 | access_fn = CHREC_LEFT (access_fn); | |
1449 | ||
1450 | if ((unsigned) loop_depth (aloop) <= min_depth) | |
1451 | continue; | |
1452 | ||
1453 | if (host_integerp (step, 0)) | |
1454 | astep = tree_low_cst (step, 0); | |
1455 | else | |
1456 | astep = L1_CACHE_LINE_SIZE; | |
1457 | ||
1458 | strides[n - 1 - loop_depth (loop) + loop_depth (aloop)] += astep * stride; | |
1459 | ||
1460 | } | |
1461 | } | |
1462 | ||
1463 | /* Returns the volume of memory references accessed between two consecutive | |
1464 | self-reuses of the reference DR. We consider the subscripts of DR in N | |
1465 | loops, and LOOP_SIZES contains the volumes of accesses in each of the | |
1466 | loops. LOOP is the innermost loop of the current loop nest. */ | |
1467 | ||
1468 | static unsigned | |
1469 | self_reuse_distance (data_reference_p dr, unsigned *loop_sizes, unsigned n, | |
1470 | struct loop *loop) | |
1471 | { | |
1472 | tree stride, access_fn; | |
1473 | HOST_WIDE_INT *strides, astride; | |
f1f41a6c | 1474 | vec<tree> access_fns; |
5c205353 | 1475 | tree ref = DR_REF (dr); |
1476 | unsigned i, ret = ~0u; | |
1477 | ||
1478 | /* In the following example: | |
1479 | ||
1480 | for (i = 0; i < N; i++) | |
1481 | for (j = 0; j < N; j++) | |
1482 | use (a[j][i]); | |
1483 | the same cache line is accessed each N steps (except if the change from | |
1484 | i to i + 1 crosses the boundary of the cache line). Thus, for self-reuse, | |
1485 | we cannot rely purely on the results of the data dependence analysis. | |
1486 | ||
1487 | Instead, we compute the stride of the reference in each loop, and consider | |
1488 | the innermost loop in that the stride is less than cache size. */ | |
1489 | ||
1490 | strides = XCNEWVEC (HOST_WIDE_INT, n); | |
1491 | access_fns = DR_ACCESS_FNS (dr); | |
1492 | ||
f1f41a6c | 1493 | FOR_EACH_VEC_ELT (access_fns, i, access_fn) |
5c205353 | 1494 | { |
1495 | /* Keep track of the reference corresponding to the subscript, so that we | |
1496 | know its stride. */ | |
1497 | while (handled_component_p (ref) && TREE_CODE (ref) != ARRAY_REF) | |
1498 | ref = TREE_OPERAND (ref, 0); | |
48e1416a | 1499 | |
5c205353 | 1500 | if (TREE_CODE (ref) == ARRAY_REF) |
1501 | { | |
1502 | stride = TYPE_SIZE_UNIT (TREE_TYPE (ref)); | |
1503 | if (host_integerp (stride, 1)) | |
1504 | astride = tree_low_cst (stride, 1); | |
1505 | else | |
1506 | astride = L1_CACHE_LINE_SIZE; | |
1507 | ||
1508 | ref = TREE_OPERAND (ref, 0); | |
1509 | } | |
1510 | else | |
1511 | astride = 1; | |
1512 | ||
1513 | add_subscript_strides (access_fn, astride, strides, n, loop); | |
1514 | } | |
1515 | ||
1516 | for (i = n; i-- > 0; ) | |
1517 | { | |
1518 | unsigned HOST_WIDE_INT s; | |
1519 | ||
1520 | s = strides[i] < 0 ? -strides[i] : strides[i]; | |
1521 | ||
1522 | if (s < (unsigned) L1_CACHE_LINE_SIZE | |
1523 | && (loop_sizes[i] | |
1524 | > (unsigned) (L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION))) | |
1525 | { | |
1526 | ret = loop_sizes[i]; | |
1527 | break; | |
1528 | } | |
1529 | } | |
1530 | ||
1531 | free (strides); | |
1532 | return ret; | |
1533 | } | |
1534 | ||
1535 | /* Determines the distance till the first reuse of each reference in REFS | |
5b5037b3 | 1536 | in the loop nest of LOOP. NO_OTHER_REFS is true if there are no other |
b920ee38 | 1537 | memory references in the loop. Return false if the analysis fails. */ |
5c205353 | 1538 | |
b920ee38 | 1539 | static bool |
5b5037b3 | 1540 | determine_loop_nest_reuse (struct loop *loop, struct mem_ref_group *refs, |
1541 | bool no_other_refs) | |
5c205353 | 1542 | { |
1543 | struct loop *nest, *aloop; | |
f1f41a6c | 1544 | vec<data_reference_p> datarefs = vec<data_reference_p>(); |
1545 | vec<ddr_p> dependences = vec<ddr_p>(); | |
5c205353 | 1546 | struct mem_ref_group *gr; |
5b5037b3 | 1547 | struct mem_ref *ref, *refb; |
f1f41a6c | 1548 | vec<loop_p> vloops = vec<loop_p>(); |
5c205353 | 1549 | unsigned *loop_data_size; |
1550 | unsigned i, j, n; | |
1551 | unsigned volume, dist, adist; | |
1552 | HOST_WIDE_INT vol; | |
1553 | data_reference_p dr; | |
1554 | ddr_p dep; | |
1555 | ||
1556 | if (loop->inner) | |
b920ee38 | 1557 | return true; |
5c205353 | 1558 | |
1559 | /* Find the outermost loop of the loop nest of loop (we require that | |
1560 | there are no sibling loops inside the nest). */ | |
1561 | nest = loop; | |
1562 | while (1) | |
1563 | { | |
1564 | aloop = loop_outer (nest); | |
1565 | ||
1566 | if (aloop == current_loops->tree_root | |
1567 | || aloop->inner->next) | |
1568 | break; | |
1569 | ||
1570 | nest = aloop; | |
1571 | } | |
1572 | ||
1573 | /* For each loop, determine the amount of data accessed in each iteration. | |
1574 | We use this to estimate whether the reference is evicted from the | |
1575 | cache before its reuse. */ | |
1576 | find_loop_nest (nest, &vloops); | |
f1f41a6c | 1577 | n = vloops.length (); |
5c205353 | 1578 | loop_data_size = XNEWVEC (unsigned, n); |
1579 | volume = volume_of_references (refs); | |
1580 | i = n; | |
1581 | while (i-- != 0) | |
1582 | { | |
1583 | loop_data_size[i] = volume; | |
1584 | /* Bound the volume by the L2 cache size, since above this bound, | |
1585 | all dependence distances are equivalent. */ | |
1586 | if (volume > L2_CACHE_SIZE_BYTES) | |
1587 | continue; | |
1588 | ||
f1f41a6c | 1589 | aloop = vloops[i]; |
fee017b3 | 1590 | vol = estimated_stmt_executions_int (aloop); |
b0b097b4 | 1591 | if (vol == -1) |
5c205353 | 1592 | vol = expected_loop_iterations (aloop); |
1593 | volume *= vol; | |
1594 | } | |
1595 | ||
1596 | /* Prepare the references in the form suitable for data dependence | |
bef304b8 | 1597 | analysis. We ignore unanalyzable data references (the results |
5c205353 | 1598 | are used just as a heuristics to estimate temporality of the |
1599 | references, hence we do not need to worry about correctness). */ | |
1600 | for (gr = refs; gr; gr = gr->next) | |
1601 | for (ref = gr->refs; ref; ref = ref->next) | |
1602 | { | |
221a697e | 1603 | dr = create_data_ref (nest, loop_containing_stmt (ref->stmt), |
1604 | ref->mem, ref->stmt, !ref->write_p); | |
5c205353 | 1605 | |
1606 | if (dr) | |
1607 | { | |
1608 | ref->reuse_distance = volume; | |
1609 | dr->aux = ref; | |
f1f41a6c | 1610 | datarefs.safe_push (dr); |
5c205353 | 1611 | } |
5b5037b3 | 1612 | else |
1613 | no_other_refs = false; | |
5c205353 | 1614 | } |
1615 | ||
f1f41a6c | 1616 | FOR_EACH_VEC_ELT (datarefs, i, dr) |
5c205353 | 1617 | { |
1618 | dist = self_reuse_distance (dr, loop_data_size, n, loop); | |
45ba1503 | 1619 | ref = (struct mem_ref *) dr->aux; |
5c205353 | 1620 | if (ref->reuse_distance > dist) |
1621 | ref->reuse_distance = dist; | |
5b5037b3 | 1622 | |
1623 | if (no_other_refs) | |
1624 | ref->independent_p = true; | |
5c205353 | 1625 | } |
1626 | ||
b920ee38 | 1627 | if (!compute_all_dependences (datarefs, &dependences, vloops, true)) |
1628 | return false; | |
5c205353 | 1629 | |
f1f41a6c | 1630 | FOR_EACH_VEC_ELT (dependences, i, dep) |
5c205353 | 1631 | { |
1632 | if (DDR_ARE_DEPENDENT (dep) == chrec_known) | |
1633 | continue; | |
1634 | ||
45ba1503 | 1635 | ref = (struct mem_ref *) DDR_A (dep)->aux; |
1636 | refb = (struct mem_ref *) DDR_B (dep)->aux; | |
5b5037b3 | 1637 | |
5c205353 | 1638 | if (DDR_ARE_DEPENDENT (dep) == chrec_dont_know |
1639 | || DDR_NUM_DIST_VECTS (dep) == 0) | |
1640 | { | |
bef304b8 | 1641 | /* If the dependence cannot be analyzed, assume that there might be |
5c205353 | 1642 | a reuse. */ |
1643 | dist = 0; | |
48e1416a | 1644 | |
5b5037b3 | 1645 | ref->independent_p = false; |
1646 | refb->independent_p = false; | |
5c205353 | 1647 | } |
1648 | else | |
1649 | { | |
bef304b8 | 1650 | /* The distance vectors are normalized to be always lexicographically |
5c205353 | 1651 | positive, hence we cannot tell just from them whether DDR_A comes |
1652 | before DDR_B or vice versa. However, it is not important, | |
1653 | anyway -- if DDR_A is close to DDR_B, then it is either reused in | |
1654 | DDR_B (and it is not nontemporal), or it reuses the value of DDR_B | |
1655 | in cache (and marking it as nontemporal would not affect | |
1656 | anything). */ | |
1657 | ||
1658 | dist = volume; | |
1659 | for (j = 0; j < DDR_NUM_DIST_VECTS (dep); j++) | |
1660 | { | |
1661 | adist = volume_of_dist_vector (DDR_DIST_VECT (dep, j), | |
1662 | loop_data_size, n); | |
1663 | ||
5b5037b3 | 1664 | /* If this is a dependence in the innermost loop (i.e., the |
1665 | distances in all superloops are zero) and it is not | |
1666 | the trivial self-dependence with distance zero, record that | |
1667 | the references are not completely independent. */ | |
1668 | if (lambda_vector_zerop (DDR_DIST_VECT (dep, j), n - 1) | |
1669 | && (ref != refb | |
1670 | || DDR_DIST_VECT (dep, j)[n-1] != 0)) | |
1671 | { | |
1672 | ref->independent_p = false; | |
1673 | refb->independent_p = false; | |
1674 | } | |
1675 | ||
5c205353 | 1676 | /* Ignore accesses closer than |
1677 | L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION, | |
1678 | so that we use nontemporal prefetches e.g. if single memory | |
1679 | location is accessed several times in a single iteration of | |
1680 | the loop. */ | |
1681 | if (adist < L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION) | |
1682 | continue; | |
1683 | ||
1684 | if (adist < dist) | |
1685 | dist = adist; | |
1686 | } | |
1687 | } | |
1688 | ||
5c205353 | 1689 | if (ref->reuse_distance > dist) |
1690 | ref->reuse_distance = dist; | |
5b5037b3 | 1691 | if (refb->reuse_distance > dist) |
1692 | refb->reuse_distance = dist; | |
5c205353 | 1693 | } |
1694 | ||
1695 | free_dependence_relations (dependences); | |
1696 | free_data_refs (datarefs); | |
1697 | free (loop_data_size); | |
1698 | ||
1699 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1700 | { | |
1701 | fprintf (dump_file, "Reuse distances:\n"); | |
1702 | for (gr = refs; gr; gr = gr->next) | |
1703 | for (ref = gr->refs; ref; ref = ref->next) | |
1704 | fprintf (dump_file, " ref %p distance %u\n", | |
1705 | (void *) ref, ref->reuse_distance); | |
1706 | } | |
b920ee38 | 1707 | |
1708 | return true; | |
5c205353 | 1709 | } |
1710 | ||
76595608 | 1711 | /* Determine whether or not the trip count to ahead ratio is too small based |
1712 | on prefitablility consideration. | |
0ab353e1 | 1713 | AHEAD: the iteration ahead distance, |
76595608 | 1714 | EST_NITER: the estimated trip count. */ |
1715 | ||
1716 | static bool | |
1717 | trip_count_to_ahead_ratio_too_small_p (unsigned ahead, HOST_WIDE_INT est_niter) | |
1718 | { | |
1719 | /* Assume trip count to ahead ratio is big enough if the trip count could not | |
1720 | be estimated at compile time. */ | |
1721 | if (est_niter < 0) | |
1722 | return false; | |
1723 | ||
1724 | if (est_niter < (HOST_WIDE_INT) (TRIP_COUNT_TO_AHEAD_RATIO * ahead)) | |
1725 | { | |
1726 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1727 | fprintf (dump_file, | |
1728 | "Not prefetching -- loop estimated to roll only %d times\n", | |
1729 | (int) est_niter); | |
1730 | return true; | |
1731 | } | |
1732 | ||
1733 | return false; | |
1734 | } | |
1735 | ||
1736 | /* Determine whether or not the number of memory references in the loop is | |
1737 | reasonable based on the profitablity and compilation time considerations. | |
0ab353e1 | 1738 | NINSNS: estimated number of instructions in the loop, |
0ab353e1 | 1739 | MEM_REF_COUNT: total number of memory references in the loop. */ |
1740 | ||
48e1416a | 1741 | static bool |
76595608 | 1742 | mem_ref_count_reasonable_p (unsigned ninsns, unsigned mem_ref_count) |
0ab353e1 | 1743 | { |
76595608 | 1744 | int insn_to_mem_ratio; |
0ab353e1 | 1745 | |
1746 | if (mem_ref_count == 0) | |
1747 | return false; | |
1748 | ||
76595608 | 1749 | /* Miss rate computation (is_miss_rate_acceptable) and dependence analysis |
1750 | (compute_all_dependences) have high costs based on quadratic complexity. | |
1751 | To avoid huge compilation time, we give up prefetching if mem_ref_count | |
1752 | is too large. */ | |
1753 | if (mem_ref_count > PREFETCH_MAX_MEM_REFS_PER_LOOP) | |
1754 | return false; | |
1755 | ||
48e1416a | 1756 | /* Prefetching improves performance by overlapping cache missing |
1757 | memory accesses with CPU operations. If the loop does not have | |
1758 | enough CPU operations to overlap with memory operations, prefetching | |
1759 | won't give a significant benefit. One approximate way of checking | |
1760 | this is to require the ratio of instructions to memory references to | |
0ab353e1 | 1761 | be above a certain limit. This approximation works well in practice. |
1762 | TODO: Implement a more precise computation by estimating the time | |
1763 | for each CPU or memory op in the loop. Time estimates for memory ops | |
1764 | should account for cache misses. */ | |
48e1416a | 1765 | insn_to_mem_ratio = ninsns / mem_ref_count; |
0ab353e1 | 1766 | |
1767 | if (insn_to_mem_ratio < PREFETCH_MIN_INSN_TO_MEM_RATIO) | |
3665c1ba | 1768 | { |
1769 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1770 | fprintf (dump_file, | |
1771 | "Not prefetching -- instruction to memory reference ratio (%d) too small\n", | |
1772 | insn_to_mem_ratio); | |
1773 | return false; | |
1774 | } | |
0ab353e1 | 1775 | |
76595608 | 1776 | return true; |
1777 | } | |
1778 | ||
1779 | /* Determine whether or not the instruction to prefetch ratio in the loop is | |
1780 | too small based on the profitablity consideration. | |
1781 | NINSNS: estimated number of instructions in the loop, | |
1782 | PREFETCH_COUNT: an estimate of the number of prefetches, | |
1783 | UNROLL_FACTOR: the factor to unroll the loop if prefetching. */ | |
1784 | ||
1785 | static bool | |
1786 | insn_to_prefetch_ratio_too_small_p (unsigned ninsns, unsigned prefetch_count, | |
1787 | unsigned unroll_factor) | |
1788 | { | |
1789 | int insn_to_prefetch_ratio; | |
1790 | ||
016efb93 | 1791 | /* Prefetching most likely causes performance degradation when the instruction |
1792 | to prefetch ratio is too small. Too many prefetch instructions in a loop | |
1793 | may reduce the I-cache performance. | |
3fa57e84 | 1794 | (unroll_factor * ninsns) is used to estimate the number of instructions in |
1795 | the unrolled loop. This implementation is a bit simplistic -- the number | |
1796 | of issued prefetch instructions is also affected by unrolling. So, | |
1797 | prefetch_mod and the unroll factor should be taken into account when | |
1798 | determining prefetch_count. Also, the number of insns of the unrolled | |
1799 | loop will usually be significantly smaller than the number of insns of the | |
1800 | original loop * unroll_factor (at least the induction variable increases | |
1801 | and the exit branches will get eliminated), so it might be better to use | |
1802 | tree_estimate_loop_size + estimated_unrolled_size. */ | |
016efb93 | 1803 | insn_to_prefetch_ratio = (unroll_factor * ninsns) / prefetch_count; |
1804 | if (insn_to_prefetch_ratio < MIN_INSN_TO_PREFETCH_RATIO) | |
0ab353e1 | 1805 | { |
016efb93 | 1806 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1807 | fprintf (dump_file, | |
1808 | "Not prefetching -- instruction to prefetch ratio (%d) too small\n", | |
1809 | insn_to_prefetch_ratio); | |
76595608 | 1810 | return true; |
0ab353e1 | 1811 | } |
48e1416a | 1812 | |
76595608 | 1813 | return false; |
0ab353e1 | 1814 | } |
1815 | ||
1816 | ||
8dfbf380 | 1817 | /* Issue prefetch instructions for array references in LOOP. Returns |
7194de72 | 1818 | true if the LOOP was unrolled. */ |
8dfbf380 | 1819 | |
1820 | static bool | |
7194de72 | 1821 | loop_prefetch_arrays (struct loop *loop) |
8dfbf380 | 1822 | { |
1823 | struct mem_ref_group *refs; | |
78f46d45 | 1824 | unsigned ahead, ninsns, time, unroll_factor; |
1825 | HOST_WIDE_INT est_niter; | |
8dfbf380 | 1826 | struct tree_niter_desc desc; |
5b5037b3 | 1827 | bool unrolled = false, no_other_refs; |
0ab353e1 | 1828 | unsigned prefetch_count; |
1829 | unsigned mem_ref_count; | |
8dfbf380 | 1830 | |
0bfd8d5c | 1831 | if (optimize_loop_nest_for_size_p (loop)) |
a30d0a5b | 1832 | { |
1833 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1834 | fprintf (dump_file, " ignored (cold area)\n"); | |
1835 | return false; | |
1836 | } | |
1837 | ||
76595608 | 1838 | /* FIXME: the time should be weighted by the probabilities of the blocks in |
1839 | the loop body. */ | |
1840 | time = tree_num_loop_insns (loop, &eni_time_weights); | |
1841 | if (time == 0) | |
1842 | return false; | |
1843 | ||
1844 | ahead = (PREFETCH_LATENCY + time - 1) / time; | |
fee017b3 | 1845 | est_niter = estimated_stmt_executions_int (loop); |
b0b097b4 | 1846 | if (est_niter == -1) |
1847 | est_niter = max_stmt_executions_int (loop); | |
76595608 | 1848 | |
1849 | /* Prefetching is not likely to be profitable if the trip count to ahead | |
1850 | ratio is too small. */ | |
1851 | if (trip_count_to_ahead_ratio_too_small_p (ahead, est_niter)) | |
1852 | return false; | |
1853 | ||
1854 | ninsns = tree_num_loop_insns (loop, &eni_size_weights); | |
1855 | ||
8dfbf380 | 1856 | /* Step 1: gather the memory references. */ |
0ab353e1 | 1857 | refs = gather_memory_references (loop, &no_other_refs, &mem_ref_count); |
8dfbf380 | 1858 | |
76595608 | 1859 | /* Give up prefetching if the number of memory references in the |
1860 | loop is not reasonable based on profitablity and compilation time | |
1861 | considerations. */ | |
1862 | if (!mem_ref_count_reasonable_p (ninsns, mem_ref_count)) | |
1863 | goto fail; | |
1864 | ||
8dfbf380 | 1865 | /* Step 2: estimate the reuse effects. */ |
1866 | prune_by_reuse (refs); | |
1867 | ||
5da8318c | 1868 | if (nothing_to_prefetch_p (refs)) |
8dfbf380 | 1869 | goto fail; |
1870 | ||
b920ee38 | 1871 | if (!determine_loop_nest_reuse (loop, refs, no_other_refs)) |
1872 | goto fail; | |
5c205353 | 1873 | |
76595608 | 1874 | /* Step 3: determine unroll factor. */ |
78f46d45 | 1875 | unroll_factor = determine_unroll_factor (loop, refs, ninsns, &desc, |
1876 | est_niter); | |
5da8318c | 1877 | |
1878 | /* Estimate prefetch count for the unrolled loop. */ | |
1879 | prefetch_count = estimate_prefetch_count (refs, unroll_factor); | |
1880 | if (prefetch_count == 0) | |
1881 | goto fail; | |
1882 | ||
78f46d45 | 1883 | if (dump_file && (dump_flags & TDF_DETAILS)) |
48e1416a | 1884 | fprintf (dump_file, "Ahead %d, unroll factor %d, trip count " |
f937ec59 | 1885 | HOST_WIDE_INT_PRINT_DEC "\n" |
48e1416a | 1886 | "insn count %d, mem ref count %d, prefetch count %d\n", |
1887 | ahead, unroll_factor, est_niter, | |
1888 | ninsns, mem_ref_count, prefetch_count); | |
0ab353e1 | 1889 | |
76595608 | 1890 | /* Prefetching is not likely to be profitable if the instruction to prefetch |
1891 | ratio is too small. */ | |
1892 | if (insn_to_prefetch_ratio_too_small_p (ninsns, prefetch_count, | |
1893 | unroll_factor)) | |
0ab353e1 | 1894 | goto fail; |
1895 | ||
1896 | mark_nontemporal_stores (loop, refs); | |
78f46d45 | 1897 | |
8dfbf380 | 1898 | /* Step 4: what to prefetch? */ |
1899 | if (!schedule_prefetches (refs, unroll_factor, ahead)) | |
1900 | goto fail; | |
1901 | ||
1902 | /* Step 5: unroll the loop. TODO -- peeling of first and last few | |
1903 | iterations so that we do not issue superfluous prefetches. */ | |
1904 | if (unroll_factor != 1) | |
1905 | { | |
7194de72 | 1906 | tree_unroll_loop (loop, unroll_factor, |
8dfbf380 | 1907 | single_dom_exit (loop), &desc); |
1908 | unrolled = true; | |
1909 | } | |
1910 | ||
1911 | /* Step 6: issue the prefetches. */ | |
1912 | issue_prefetches (refs, unroll_factor, ahead); | |
1913 | ||
1914 | fail: | |
1915 | release_mem_refs (refs); | |
1916 | return unrolled; | |
1917 | } | |
1918 | ||
7194de72 | 1919 | /* Issue prefetch instructions for array references in loops. */ |
8dfbf380 | 1920 | |
4c641bf8 | 1921 | unsigned int |
7194de72 | 1922 | tree_ssa_prefetch_arrays (void) |
8dfbf380 | 1923 | { |
17519ba0 | 1924 | loop_iterator li; |
8dfbf380 | 1925 | struct loop *loop; |
1926 | bool unrolled = false; | |
4c641bf8 | 1927 | int todo_flags = 0; |
8dfbf380 | 1928 | |
1929 | if (!HAVE_prefetch | |
1930 | /* It is possible to ask compiler for say -mtune=i486 -march=pentium4. | |
1931 | -mtune=i486 causes us having PREFETCH_BLOCK 0, since this is part | |
1932 | of processor costs and i486 does not have prefetch, but | |
1933 | -march=pentium4 causes HAVE_prefetch to be true. Ugh. */ | |
1934 | || PREFETCH_BLOCK == 0) | |
4c641bf8 | 1935 | return 0; |
8dfbf380 | 1936 | |
07804af5 | 1937 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1938 | { | |
1939 | fprintf (dump_file, "Prefetching parameters:\n"); | |
1940 | fprintf (dump_file, " simultaneous prefetches: %d\n", | |
1941 | SIMULTANEOUS_PREFETCHES); | |
1942 | fprintf (dump_file, " prefetch latency: %d\n", PREFETCH_LATENCY); | |
07804af5 | 1943 | fprintf (dump_file, " prefetch block size: %d\n", PREFETCH_BLOCK); |
0c916a7b | 1944 | fprintf (dump_file, " L1 cache size: %d lines, %d kB\n", |
1945 | L1_CACHE_SIZE_BYTES / L1_CACHE_LINE_SIZE, L1_CACHE_SIZE); | |
5c205353 | 1946 | fprintf (dump_file, " L1 cache line size: %d\n", L1_CACHE_LINE_SIZE); |
48e1416a | 1947 | fprintf (dump_file, " L2 cache size: %d kB\n", L2_CACHE_SIZE); |
1948 | fprintf (dump_file, " min insn-to-prefetch ratio: %d \n", | |
0ab353e1 | 1949 | MIN_INSN_TO_PREFETCH_RATIO); |
48e1416a | 1950 | fprintf (dump_file, " min insn-to-mem ratio: %d \n", |
0ab353e1 | 1951 | PREFETCH_MIN_INSN_TO_MEM_RATIO); |
07804af5 | 1952 | fprintf (dump_file, "\n"); |
1953 | } | |
1954 | ||
8dfbf380 | 1955 | initialize_original_copy_tables (); |
1956 | ||
b9a16870 | 1957 | if (!builtin_decl_explicit_p (BUILT_IN_PREFETCH)) |
8dfbf380 | 1958 | { |
dbdf4b31 | 1959 | tree type = build_function_type_list (void_type_node, |
1960 | const_ptr_type_node, NULL_TREE); | |
54be5d7e | 1961 | tree decl = add_builtin_function ("__builtin_prefetch", type, |
1962 | BUILT_IN_PREFETCH, BUILT_IN_NORMAL, | |
1963 | NULL, NULL_TREE); | |
8dfbf380 | 1964 | DECL_IS_NOVOPS (decl) = true; |
b9a16870 | 1965 | set_builtin_decl (BUILT_IN_PREFETCH, decl, false); |
8dfbf380 | 1966 | } |
1967 | ||
1968 | /* We assume that size of cache line is a power of two, so verify this | |
1969 | here. */ | |
1970 | gcc_assert ((PREFETCH_BLOCK & (PREFETCH_BLOCK - 1)) == 0); | |
1971 | ||
17519ba0 | 1972 | FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) |
8dfbf380 | 1973 | { |
8dfbf380 | 1974 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1975 | fprintf (dump_file, "Processing loop %d:\n", loop->num); | |
1976 | ||
7194de72 | 1977 | unrolled |= loop_prefetch_arrays (loop); |
8dfbf380 | 1978 | |
1979 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1980 | fprintf (dump_file, "\n\n"); | |
1981 | } | |
1982 | ||
1983 | if (unrolled) | |
1984 | { | |
1985 | scev_reset (); | |
4c641bf8 | 1986 | todo_flags |= TODO_cleanup_cfg; |
8dfbf380 | 1987 | } |
1988 | ||
1989 | free_original_copy_tables (); | |
4c641bf8 | 1990 | return todo_flags; |
8dfbf380 | 1991 | } |