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b076a3fd | 1 | /* Array prefetching. |
5624e564 | 2 | Copyright (C) 2005-2015 Free Software Foundation, Inc. |
b8698a0f | 3 | |
b076a3fd | 4 | This file is part of GCC. |
b8698a0f | 5 | |
b076a3fd ZD |
6 | GCC is free software; you can redistribute it and/or modify it |
7 | under the terms of the GNU General Public License as published by the | |
9dcd6f09 | 8 | Free Software Foundation; either version 3, or (at your option) any |
b076a3fd | 9 | later version. |
b8698a0f | 10 | |
b076a3fd ZD |
11 | GCC is distributed in the hope that it will be useful, but WITHOUT |
12 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
b8698a0f | 15 | |
b076a3fd | 16 | You should have received a copy of the GNU General Public License |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
b076a3fd ZD |
19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
40e23961 MC |
24 | #include "hash-set.h" |
25 | #include "machmode.h" | |
26 | #include "vec.h" | |
27 | #include "double-int.h" | |
28 | #include "input.h" | |
29 | #include "alias.h" | |
30 | #include "symtab.h" | |
31 | #include "wide-int.h" | |
32 | #include "inchash.h" | |
b076a3fd | 33 | #include "tree.h" |
40e23961 | 34 | #include "fold-const.h" |
d8a2d370 | 35 | #include "stor-layout.h" |
b076a3fd | 36 | #include "tm_p.h" |
60393bbc | 37 | #include "predict.h" |
60393bbc | 38 | #include "hard-reg-set.h" |
60393bbc AM |
39 | #include "function.h" |
40 | #include "dominance.h" | |
41 | #include "cfg.h" | |
b076a3fd | 42 | #include "basic-block.h" |
cf835838 | 43 | #include "tree-pretty-print.h" |
2fb9a547 AM |
44 | #include "tree-ssa-alias.h" |
45 | #include "internal-fn.h" | |
46 | #include "gimple-expr.h" | |
47 | #include "is-a.h" | |
18f429e2 | 48 | #include "gimple.h" |
45b0be94 | 49 | #include "gimplify.h" |
5be5c238 | 50 | #include "gimple-iterator.h" |
18f429e2 | 51 | #include "gimplify-me.h" |
442b4905 | 52 | #include "gimple-ssa.h" |
e28030cf AM |
53 | #include "tree-ssa-loop-ivopts.h" |
54 | #include "tree-ssa-loop-manip.h" | |
55 | #include "tree-ssa-loop-niter.h" | |
442b4905 AM |
56 | #include "tree-ssa-loop.h" |
57 | #include "tree-into-ssa.h" | |
b076a3fd | 58 | #include "cfgloop.h" |
b076a3fd | 59 | #include "tree-pass.h" |
b076a3fd | 60 | #include "insn-config.h" |
b076a3fd ZD |
61 | #include "tree-chrec.h" |
62 | #include "tree-scalar-evolution.h" | |
718f9c0f | 63 | #include "diagnostic-core.h" |
b076a3fd ZD |
64 | #include "params.h" |
65 | #include "langhooks.h" | |
7f9bc51b | 66 | #include "tree-inline.h" |
5417e022 | 67 | #include "tree-data-ref.h" |
2eb79bbb SB |
68 | |
69 | ||
70 | /* FIXME: Needed for optabs, but this should all be moved to a TBD interface | |
71 | between the GIMPLE and RTL worlds. */ | |
36566b39 PK |
72 | #include "hashtab.h" |
73 | #include "rtl.h" | |
74 | #include "flags.h" | |
75 | #include "statistics.h" | |
76 | #include "real.h" | |
77 | #include "fixed-value.h" | |
78 | #include "expmed.h" | |
79 | #include "dojump.h" | |
80 | #include "explow.h" | |
81 | #include "calls.h" | |
82 | #include "emit-rtl.h" | |
83 | #include "varasm.h" | |
84 | #include "stmt.h" | |
2eb79bbb | 85 | #include "expr.h" |
b0710fe1 | 86 | #include "insn-codes.h" |
79f5e442 | 87 | #include "optabs.h" |
1c1ad7bb | 88 | #include "recog.h" |
b076a3fd ZD |
89 | |
90 | /* This pass inserts prefetch instructions to optimize cache usage during | |
91 | accesses to arrays in loops. It processes loops sequentially and: | |
92 | ||
93 | 1) Gathers all memory references in the single loop. | |
94 | 2) For each of the references it decides when it is profitable to prefetch | |
95 | it. To do it, we evaluate the reuse among the accesses, and determines | |
96 | two values: PREFETCH_BEFORE (meaning that it only makes sense to do | |
97 | prefetching in the first PREFETCH_BEFORE iterations of the loop) and | |
98 | PREFETCH_MOD (meaning that it only makes sense to prefetch in the | |
99 | iterations of the loop that are zero modulo PREFETCH_MOD). For example | |
100 | (assuming cache line size is 64 bytes, char has size 1 byte and there | |
101 | is no hardware sequential prefetch): | |
102 | ||
103 | char *a; | |
104 | for (i = 0; i < max; i++) | |
105 | { | |
106 | a[255] = ...; (0) | |
107 | a[i] = ...; (1) | |
108 | a[i + 64] = ...; (2) | |
109 | a[16*i] = ...; (3) | |
110 | a[187*i] = ...; (4) | |
111 | a[187*i + 50] = ...; (5) | |
112 | } | |
113 | ||
114 | (0) obviously has PREFETCH_BEFORE 1 | |
115 | (1) has PREFETCH_BEFORE 64, since (2) accesses the same memory | |
116 | location 64 iterations before it, and PREFETCH_MOD 64 (since | |
117 | it hits the same cache line otherwise). | |
118 | (2) has PREFETCH_MOD 64 | |
119 | (3) has PREFETCH_MOD 4 | |
120 | (4) has PREFETCH_MOD 1. We do not set PREFETCH_BEFORE here, since | |
bae077dc | 121 | the cache line accessed by (5) is the same with probability only |
b076a3fd ZD |
122 | 7/32. |
123 | (5) has PREFETCH_MOD 1 as well. | |
124 | ||
5417e022 ZD |
125 | Additionally, we use data dependence analysis to determine for each |
126 | reference the distance till the first reuse; this information is used | |
127 | to determine the temporality of the issued prefetch instruction. | |
128 | ||
b076a3fd ZD |
129 | 3) We determine how much ahead we need to prefetch. The number of |
130 | iterations needed is time to fetch / time spent in one iteration of | |
131 | the loop. The problem is that we do not know either of these values, | |
132 | so we just make a heuristic guess based on a magic (possibly) | |
133 | target-specific constant and size of the loop. | |
134 | ||
135 | 4) Determine which of the references we prefetch. We take into account | |
136 | that there is a maximum number of simultaneous prefetches (provided | |
137 | by machine description). We prefetch as many prefetches as possible | |
138 | while still within this bound (starting with those with lowest | |
139 | prefetch_mod, since they are responsible for most of the cache | |
140 | misses). | |
b8698a0f | 141 | |
b076a3fd ZD |
142 | 5) We unroll and peel loops so that we are able to satisfy PREFETCH_MOD |
143 | and PREFETCH_BEFORE requirements (within some bounds), and to avoid | |
144 | prefetching nonaccessed memory. | |
145 | TODO -- actually implement peeling. | |
b8698a0f | 146 | |
b076a3fd ZD |
147 | 6) We actually emit the prefetch instructions. ??? Perhaps emit the |
148 | prefetch instructions with guards in cases where 5) was not sufficient | |
149 | to satisfy the constraints? | |
150 | ||
0bbe50f6 CF |
151 | A cost model is implemented to determine whether or not prefetching is |
152 | profitable for a given loop. The cost model has three heuristics: | |
153 | ||
154 | 1. Function trip_count_to_ahead_ratio_too_small_p implements a | |
155 | heuristic that determines whether or not the loop has too few | |
156 | iterations (compared to ahead). Prefetching is not likely to be | |
157 | beneficial if the trip count to ahead ratio is below a certain | |
158 | minimum. | |
159 | ||
160 | 2. Function mem_ref_count_reasonable_p implements a heuristic that | |
161 | determines whether the given loop has enough CPU ops that can be | |
162 | overlapped with cache missing memory ops. If not, the loop | |
163 | won't benefit from prefetching. In the implementation, | |
164 | prefetching is not considered beneficial if the ratio between | |
165 | the instruction count and the mem ref count is below a certain | |
166 | minimum. | |
167 | ||
168 | 3. Function insn_to_prefetch_ratio_too_small_p implements a | |
169 | heuristic that disables prefetching in a loop if the prefetching | |
170 | cost is above a certain limit. The relative prefetching cost is | |
171 | estimated by taking the ratio between the prefetch count and the | |
172 | total intruction count (this models the I-cache cost). | |
173 | ||
db34470d | 174 | The limits used in these heuristics are defined as parameters with |
b8698a0f | 175 | reasonable default values. Machine-specific default values will be |
db34470d | 176 | added later. |
b8698a0f | 177 | |
b076a3fd ZD |
178 | Some other TODO: |
179 | -- write and use more general reuse analysis (that could be also used | |
180 | in other cache aimed loop optimizations) | |
181 | -- make it behave sanely together with the prefetches given by user | |
182 | (now we just ignore them; at the very least we should avoid | |
183 | optimizing loops in that user put his own prefetches) | |
184 | -- we assume cache line size alignment of arrays; this could be | |
185 | improved. */ | |
186 | ||
187 | /* Magic constants follow. These should be replaced by machine specific | |
188 | numbers. */ | |
189 | ||
b076a3fd ZD |
190 | /* True if write can be prefetched by a read prefetch. */ |
191 | ||
192 | #ifndef WRITE_CAN_USE_READ_PREFETCH | |
193 | #define WRITE_CAN_USE_READ_PREFETCH 1 | |
194 | #endif | |
195 | ||
196 | /* True if read can be prefetched by a write prefetch. */ | |
197 | ||
198 | #ifndef READ_CAN_USE_WRITE_PREFETCH | |
199 | #define READ_CAN_USE_WRITE_PREFETCH 0 | |
200 | #endif | |
201 | ||
47eb5b32 ZD |
202 | /* The size of the block loaded by a single prefetch. Usually, this is |
203 | the same as cache line size (at the moment, we only consider one level | |
204 | of cache hierarchy). */ | |
b076a3fd ZD |
205 | |
206 | #ifndef PREFETCH_BLOCK | |
47eb5b32 | 207 | #define PREFETCH_BLOCK L1_CACHE_LINE_SIZE |
b076a3fd ZD |
208 | #endif |
209 | ||
210 | /* Do we have a forward hardware sequential prefetching? */ | |
211 | ||
212 | #ifndef HAVE_FORWARD_PREFETCH | |
213 | #define HAVE_FORWARD_PREFETCH 0 | |
214 | #endif | |
215 | ||
216 | /* Do we have a backward hardware sequential prefetching? */ | |
217 | ||
218 | #ifndef HAVE_BACKWARD_PREFETCH | |
219 | #define HAVE_BACKWARD_PREFETCH 0 | |
220 | #endif | |
221 | ||
222 | /* In some cases we are only able to determine that there is a certain | |
223 | probability that the two accesses hit the same cache line. In this | |
224 | case, we issue the prefetches for both of them if this probability | |
fa10beec | 225 | is less then (1000 - ACCEPTABLE_MISS_RATE) per thousand. */ |
b076a3fd ZD |
226 | |
227 | #ifndef ACCEPTABLE_MISS_RATE | |
228 | #define ACCEPTABLE_MISS_RATE 50 | |
229 | #endif | |
230 | ||
231 | #ifndef HAVE_prefetch | |
232 | #define HAVE_prefetch 0 | |
233 | #endif | |
234 | ||
46cb0441 ZD |
235 | #define L1_CACHE_SIZE_BYTES ((unsigned) (L1_CACHE_SIZE * 1024)) |
236 | #define L2_CACHE_SIZE_BYTES ((unsigned) (L2_CACHE_SIZE * 1024)) | |
5417e022 ZD |
237 | |
238 | /* We consider a memory access nontemporal if it is not reused sooner than | |
239 | after L2_CACHE_SIZE_BYTES of memory are accessed. However, we ignore | |
240 | accesses closer than L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION, | |
241 | so that we use nontemporal prefetches e.g. if single memory location | |
242 | is accessed several times in a single iteration of the loop. */ | |
243 | #define NONTEMPORAL_FRACTION 16 | |
244 | ||
79f5e442 ZD |
245 | /* In case we have to emit a memory fence instruction after the loop that |
246 | uses nontemporal stores, this defines the builtin to use. */ | |
247 | ||
248 | #ifndef FENCE_FOLLOWING_MOVNT | |
249 | #define FENCE_FOLLOWING_MOVNT NULL_TREE | |
250 | #endif | |
251 | ||
9bf4598b CF |
252 | /* It is not profitable to prefetch when the trip count is not at |
253 | least TRIP_COUNT_TO_AHEAD_RATIO times the prefetch ahead distance. | |
254 | For example, in a loop with a prefetch ahead distance of 10, | |
255 | supposing that TRIP_COUNT_TO_AHEAD_RATIO is equal to 4, it is | |
256 | profitable to prefetch when the trip count is greater or equal to | |
257 | 40. In that case, 30 out of the 40 iterations will benefit from | |
258 | prefetching. */ | |
259 | ||
260 | #ifndef TRIP_COUNT_TO_AHEAD_RATIO | |
261 | #define TRIP_COUNT_TO_AHEAD_RATIO 4 | |
262 | #endif | |
263 | ||
b076a3fd ZD |
264 | /* The group of references between that reuse may occur. */ |
265 | ||
266 | struct mem_ref_group | |
267 | { | |
268 | tree base; /* Base of the reference. */ | |
81f32326 | 269 | tree step; /* Step of the reference. */ |
b076a3fd ZD |
270 | struct mem_ref *refs; /* References in the group. */ |
271 | struct mem_ref_group *next; /* Next group of references. */ | |
272 | }; | |
273 | ||
274 | /* Assigned to PREFETCH_BEFORE when all iterations are to be prefetched. */ | |
275 | ||
276 | #define PREFETCH_ALL (~(unsigned HOST_WIDE_INT) 0) | |
277 | ||
8532678c CF |
278 | /* Do not generate a prefetch if the unroll factor is significantly less |
279 | than what is required by the prefetch. This is to avoid redundant | |
f7963a7c CF |
280 | prefetches. For example, when prefetch_mod is 16 and unroll_factor is |
281 | 2, prefetching requires unrolling the loop 16 times, but | |
282 | the loop is actually unrolled twice. In this case (ratio = 8), | |
8532678c CF |
283 | prefetching is not likely to be beneficial. */ |
284 | ||
285 | #ifndef PREFETCH_MOD_TO_UNROLL_FACTOR_RATIO | |
f7963a7c | 286 | #define PREFETCH_MOD_TO_UNROLL_FACTOR_RATIO 4 |
8532678c CF |
287 | #endif |
288 | ||
0bbe50f6 CF |
289 | /* Some of the prefetch computations have quadratic complexity. We want to |
290 | avoid huge compile times and, therefore, want to limit the amount of | |
291 | memory references per loop where we consider prefetching. */ | |
292 | ||
293 | #ifndef PREFETCH_MAX_MEM_REFS_PER_LOOP | |
294 | #define PREFETCH_MAX_MEM_REFS_PER_LOOP 200 | |
295 | #endif | |
296 | ||
b076a3fd ZD |
297 | /* The memory reference. */ |
298 | ||
299 | struct mem_ref | |
300 | { | |
726a989a | 301 | gimple stmt; /* Statement in that the reference appears. */ |
b076a3fd ZD |
302 | tree mem; /* The reference. */ |
303 | HOST_WIDE_INT delta; /* Constant offset of the reference. */ | |
b076a3fd ZD |
304 | struct mem_ref_group *group; /* The group of references it belongs to. */ |
305 | unsigned HOST_WIDE_INT prefetch_mod; | |
306 | /* Prefetch only each PREFETCH_MOD-th | |
307 | iteration. */ | |
308 | unsigned HOST_WIDE_INT prefetch_before; | |
309 | /* Prefetch only first PREFETCH_BEFORE | |
310 | iterations. */ | |
5417e022 ZD |
311 | unsigned reuse_distance; /* The amount of data accessed before the first |
312 | reuse of this value. */ | |
b076a3fd | 313 | struct mem_ref *next; /* The next reference in the group. */ |
79f5e442 ZD |
314 | unsigned write_p : 1; /* Is it a write? */ |
315 | unsigned independent_p : 1; /* True if the reference is independent on | |
316 | all other references inside the loop. */ | |
317 | unsigned issue_prefetch_p : 1; /* Should we really issue the prefetch? */ | |
318 | unsigned storent_p : 1; /* True if we changed the store to a | |
319 | nontemporal one. */ | |
b076a3fd ZD |
320 | }; |
321 | ||
a5497b12 | 322 | /* Dumps information about memory reference */ |
b076a3fd | 323 | static void |
a5497b12 VK |
324 | dump_mem_details (FILE *file, tree base, tree step, |
325 | HOST_WIDE_INT delta, bool write_p) | |
b076a3fd | 326 | { |
a5497b12 VK |
327 | fprintf (file, "(base "); |
328 | print_generic_expr (file, base, TDF_SLIM); | |
b076a3fd | 329 | fprintf (file, ", step "); |
a5497b12 VK |
330 | if (cst_and_fits_in_hwi (step)) |
331 | fprintf (file, HOST_WIDE_INT_PRINT_DEC, int_cst_value (step)); | |
81f32326 | 332 | else |
a5497b12 | 333 | print_generic_expr (file, step, TDF_TREE); |
b076a3fd | 334 | fprintf (file, ")\n"); |
e324a72f | 335 | fprintf (file, " delta "); |
a5497b12 VK |
336 | fprintf (file, HOST_WIDE_INT_PRINT_DEC, delta); |
337 | fprintf (file, "\n"); | |
338 | fprintf (file, " %s\n", write_p ? "write" : "read"); | |
b076a3fd | 339 | fprintf (file, "\n"); |
a5497b12 | 340 | } |
b076a3fd | 341 | |
a5497b12 | 342 | /* Dumps information about reference REF to FILE. */ |
b076a3fd | 343 | |
a5497b12 VK |
344 | static void |
345 | dump_mem_ref (FILE *file, struct mem_ref *ref) | |
346 | { | |
347 | fprintf (file, "Reference %p:\n", (void *) ref); | |
348 | ||
349 | fprintf (file, " group %p ", (void *) ref->group); | |
350 | ||
351 | dump_mem_details (file, ref->group->base, ref->group->step, ref->delta, | |
352 | ref->write_p); | |
b076a3fd ZD |
353 | } |
354 | ||
355 | /* Finds a group with BASE and STEP in GROUPS, or creates one if it does not | |
356 | exist. */ | |
357 | ||
358 | static struct mem_ref_group * | |
81f32326 | 359 | find_or_create_group (struct mem_ref_group **groups, tree base, tree step) |
b076a3fd ZD |
360 | { |
361 | struct mem_ref_group *group; | |
362 | ||
363 | for (; *groups; groups = &(*groups)->next) | |
364 | { | |
81f32326 | 365 | if (operand_equal_p ((*groups)->step, step, 0) |
b076a3fd ZD |
366 | && operand_equal_p ((*groups)->base, base, 0)) |
367 | return *groups; | |
368 | ||
81f32326 CB |
369 | /* If step is an integer constant, keep the list of groups sorted |
370 | by decreasing step. */ | |
371 | if (cst_and_fits_in_hwi ((*groups)->step) && cst_and_fits_in_hwi (step) | |
372 | && int_cst_value ((*groups)->step) < int_cst_value (step)) | |
b076a3fd ZD |
373 | break; |
374 | } | |
375 | ||
5417e022 | 376 | group = XNEW (struct mem_ref_group); |
b076a3fd ZD |
377 | group->base = base; |
378 | group->step = step; | |
379 | group->refs = NULL; | |
380 | group->next = *groups; | |
381 | *groups = group; | |
382 | ||
383 | return group; | |
384 | } | |
385 | ||
386 | /* Records a memory reference MEM in GROUP with offset DELTA and write status | |
387 | WRITE_P. The reference occurs in statement STMT. */ | |
388 | ||
389 | static void | |
726a989a | 390 | record_ref (struct mem_ref_group *group, gimple stmt, tree mem, |
b076a3fd ZD |
391 | HOST_WIDE_INT delta, bool write_p) |
392 | { | |
393 | struct mem_ref **aref; | |
394 | ||
395 | /* Do not record the same address twice. */ | |
396 | for (aref = &group->refs; *aref; aref = &(*aref)->next) | |
397 | { | |
398 | /* It does not have to be possible for write reference to reuse the read | |
399 | prefetch, or vice versa. */ | |
400 | if (!WRITE_CAN_USE_READ_PREFETCH | |
401 | && write_p | |
402 | && !(*aref)->write_p) | |
403 | continue; | |
404 | if (!READ_CAN_USE_WRITE_PREFETCH | |
405 | && !write_p | |
406 | && (*aref)->write_p) | |
407 | continue; | |
408 | ||
409 | if ((*aref)->delta == delta) | |
410 | return; | |
411 | } | |
412 | ||
5417e022 | 413 | (*aref) = XNEW (struct mem_ref); |
b076a3fd ZD |
414 | (*aref)->stmt = stmt; |
415 | (*aref)->mem = mem; | |
416 | (*aref)->delta = delta; | |
417 | (*aref)->write_p = write_p; | |
418 | (*aref)->prefetch_before = PREFETCH_ALL; | |
419 | (*aref)->prefetch_mod = 1; | |
5417e022 | 420 | (*aref)->reuse_distance = 0; |
b076a3fd ZD |
421 | (*aref)->issue_prefetch_p = false; |
422 | (*aref)->group = group; | |
423 | (*aref)->next = NULL; | |
79f5e442 ZD |
424 | (*aref)->independent_p = false; |
425 | (*aref)->storent_p = false; | |
b076a3fd ZD |
426 | |
427 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
428 | dump_mem_ref (dump_file, *aref); | |
429 | } | |
430 | ||
431 | /* Release memory references in GROUPS. */ | |
432 | ||
433 | static void | |
434 | release_mem_refs (struct mem_ref_group *groups) | |
435 | { | |
436 | struct mem_ref_group *next_g; | |
437 | struct mem_ref *ref, *next_r; | |
438 | ||
439 | for (; groups; groups = next_g) | |
440 | { | |
441 | next_g = groups->next; | |
442 | for (ref = groups->refs; ref; ref = next_r) | |
443 | { | |
444 | next_r = ref->next; | |
445 | free (ref); | |
446 | } | |
447 | free (groups); | |
448 | } | |
449 | } | |
450 | ||
451 | /* A structure used to pass arguments to idx_analyze_ref. */ | |
452 | ||
453 | struct ar_data | |
454 | { | |
455 | struct loop *loop; /* Loop of the reference. */ | |
726a989a | 456 | gimple stmt; /* Statement of the reference. */ |
81f32326 | 457 | tree *step; /* Step of the memory reference. */ |
b076a3fd ZD |
458 | HOST_WIDE_INT *delta; /* Offset of the memory reference. */ |
459 | }; | |
460 | ||
461 | /* Analyzes a single INDEX of a memory reference to obtain information | |
462 | described at analyze_ref. Callback for for_each_index. */ | |
463 | ||
464 | static bool | |
465 | idx_analyze_ref (tree base, tree *index, void *data) | |
466 | { | |
c22940cd | 467 | struct ar_data *ar_data = (struct ar_data *) data; |
b076a3fd | 468 | tree ibase, step, stepsize; |
81f32326 | 469 | HOST_WIDE_INT idelta = 0, imult = 1; |
b076a3fd ZD |
470 | affine_iv iv; |
471 | ||
f017bf5e | 472 | if (!simple_iv (ar_data->loop, loop_containing_stmt (ar_data->stmt), |
81f32326 | 473 | *index, &iv, true)) |
b076a3fd ZD |
474 | return false; |
475 | ibase = iv.base; | |
476 | step = iv.step; | |
477 | ||
5be014d5 | 478 | if (TREE_CODE (ibase) == POINTER_PLUS_EXPR |
b076a3fd ZD |
479 | && cst_and_fits_in_hwi (TREE_OPERAND (ibase, 1))) |
480 | { | |
481 | idelta = int_cst_value (TREE_OPERAND (ibase, 1)); | |
482 | ibase = TREE_OPERAND (ibase, 0); | |
483 | } | |
484 | if (cst_and_fits_in_hwi (ibase)) | |
485 | { | |
486 | idelta += int_cst_value (ibase); | |
ff5e9a94 | 487 | ibase = build_int_cst (TREE_TYPE (ibase), 0); |
b076a3fd ZD |
488 | } |
489 | ||
490 | if (TREE_CODE (base) == ARRAY_REF) | |
491 | { | |
492 | stepsize = array_ref_element_size (base); | |
493 | if (!cst_and_fits_in_hwi (stepsize)) | |
494 | return false; | |
495 | imult = int_cst_value (stepsize); | |
8fde8b40 CB |
496 | step = fold_build2 (MULT_EXPR, sizetype, |
497 | fold_convert (sizetype, step), | |
498 | fold_convert (sizetype, stepsize)); | |
b076a3fd ZD |
499 | idelta *= imult; |
500 | } | |
501 | ||
8fde8b40 CB |
502 | if (*ar_data->step == NULL_TREE) |
503 | *ar_data->step = step; | |
504 | else | |
505 | *ar_data->step = fold_build2 (PLUS_EXPR, sizetype, | |
506 | fold_convert (sizetype, *ar_data->step), | |
507 | fold_convert (sizetype, step)); | |
b076a3fd ZD |
508 | *ar_data->delta += idelta; |
509 | *index = ibase; | |
510 | ||
511 | return true; | |
512 | } | |
513 | ||
aac8b8ed | 514 | /* Tries to express REF_P in shape &BASE + STEP * iter + DELTA, where DELTA and |
b076a3fd | 515 | STEP are integer constants and iter is number of iterations of LOOP. The |
aac8b8ed RS |
516 | reference occurs in statement STMT. Strips nonaddressable component |
517 | references from REF_P. */ | |
b076a3fd ZD |
518 | |
519 | static bool | |
aac8b8ed | 520 | analyze_ref (struct loop *loop, tree *ref_p, tree *base, |
81f32326 | 521 | tree *step, HOST_WIDE_INT *delta, |
726a989a | 522 | gimple stmt) |
b076a3fd ZD |
523 | { |
524 | struct ar_data ar_data; | |
525 | tree off; | |
526 | HOST_WIDE_INT bit_offset; | |
aac8b8ed | 527 | tree ref = *ref_p; |
b076a3fd | 528 | |
81f32326 | 529 | *step = NULL_TREE; |
b076a3fd ZD |
530 | *delta = 0; |
531 | ||
7c6dafac CF |
532 | /* First strip off the component references. Ignore bitfields. |
533 | Also strip off the real and imagine parts of a complex, so that | |
534 | they can have the same base. */ | |
535 | if (TREE_CODE (ref) == REALPART_EXPR | |
536 | || TREE_CODE (ref) == IMAGPART_EXPR | |
537 | || (TREE_CODE (ref) == COMPONENT_REF | |
538 | && DECL_NONADDRESSABLE_P (TREE_OPERAND (ref, 1)))) | |
539 | { | |
540 | if (TREE_CODE (ref) == IMAGPART_EXPR) | |
541 | *delta += int_size_in_bytes (TREE_TYPE (ref)); | |
542 | ref = TREE_OPERAND (ref, 0); | |
543 | } | |
b076a3fd | 544 | |
aac8b8ed RS |
545 | *ref_p = ref; |
546 | ||
b076a3fd ZD |
547 | for (; TREE_CODE (ref) == COMPONENT_REF; ref = TREE_OPERAND (ref, 0)) |
548 | { | |
549 | off = DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1)); | |
550 | bit_offset = TREE_INT_CST_LOW (off); | |
551 | gcc_assert (bit_offset % BITS_PER_UNIT == 0); | |
b8698a0f | 552 | |
b076a3fd ZD |
553 | *delta += bit_offset / BITS_PER_UNIT; |
554 | } | |
555 | ||
556 | *base = unshare_expr (ref); | |
557 | ar_data.loop = loop; | |
558 | ar_data.stmt = stmt; | |
559 | ar_data.step = step; | |
560 | ar_data.delta = delta; | |
561 | return for_each_index (base, idx_analyze_ref, &ar_data); | |
562 | } | |
563 | ||
564 | /* Record a memory reference REF to the list REFS. The reference occurs in | |
79f5e442 ZD |
565 | LOOP in statement STMT and it is write if WRITE_P. Returns true if the |
566 | reference was recorded, false otherwise. */ | |
b076a3fd | 567 | |
79f5e442 | 568 | static bool |
b076a3fd | 569 | gather_memory_references_ref (struct loop *loop, struct mem_ref_group **refs, |
726a989a | 570 | tree ref, bool write_p, gimple stmt) |
b076a3fd | 571 | { |
81f32326 CB |
572 | tree base, step; |
573 | HOST_WIDE_INT delta; | |
b076a3fd ZD |
574 | struct mem_ref_group *agrp; |
575 | ||
a80a2701 JJ |
576 | if (get_base_address (ref) == NULL) |
577 | return false; | |
578 | ||
aac8b8ed | 579 | if (!analyze_ref (loop, &ref, &base, &step, &delta, stmt)) |
79f5e442 | 580 | return false; |
81f32326 CB |
581 | /* If analyze_ref fails the default is a NULL_TREE. We can stop here. */ |
582 | if (step == NULL_TREE) | |
583 | return false; | |
b076a3fd | 584 | |
756f50ce | 585 | /* Stop if the address of BASE could not be taken. */ |
bc068a23 CF |
586 | if (may_be_nonaddressable_p (base)) |
587 | return false; | |
588 | ||
a5497b12 VK |
589 | /* Limit non-constant step prefetching only to the innermost loops and |
590 | only when the step is loop invariant in the entire loop nest. */ | |
591 | if (!cst_and_fits_in_hwi (step)) | |
592 | { | |
593 | if (loop->inner != NULL) | |
594 | { | |
595 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
596 | { | |
597 | fprintf (dump_file, "Memory expression %p\n",(void *) ref ); | |
598 | print_generic_expr (dump_file, ref, TDF_TREE); | |
599 | fprintf (dump_file,":"); | |
c3284718 | 600 | dump_mem_details (dump_file, base, step, delta, write_p); |
a5497b12 VK |
601 | fprintf (dump_file, |
602 | "Ignoring %p, non-constant step prefetching is " | |
603 | "limited to inner most loops \n", | |
604 | (void *) ref); | |
605 | } | |
606 | return false; | |
607 | } | |
608 | else | |
609 | { | |
610 | if (!expr_invariant_in_loop_p (loop_outermost (loop), step)) | |
611 | { | |
612 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
613 | { | |
614 | fprintf (dump_file, "Memory expression %p\n",(void *) ref ); | |
615 | print_generic_expr (dump_file, ref, TDF_TREE); | |
616 | fprintf (dump_file,":"); | |
c3284718 | 617 | dump_mem_details (dump_file, base, step, delta, write_p); |
a5497b12 VK |
618 | fprintf (dump_file, |
619 | "Not prefetching, ignoring %p due to " | |
620 | "loop variant step\n", | |
621 | (void *) ref); | |
622 | } | |
623 | return false; | |
624 | } | |
625 | } | |
626 | } | |
50814135 | 627 | |
b076a3fd ZD |
628 | /* Now we know that REF = &BASE + STEP * iter + DELTA, where DELTA and STEP |
629 | are integer constants. */ | |
630 | agrp = find_or_create_group (refs, base, step); | |
631 | record_ref (agrp, stmt, ref, delta, write_p); | |
79f5e442 ZD |
632 | |
633 | return true; | |
b076a3fd ZD |
634 | } |
635 | ||
79f5e442 ZD |
636 | /* Record the suitable memory references in LOOP. NO_OTHER_REFS is set to |
637 | true if there are no other memory references inside the loop. */ | |
b076a3fd ZD |
638 | |
639 | static struct mem_ref_group * | |
db34470d | 640 | gather_memory_references (struct loop *loop, bool *no_other_refs, unsigned *ref_count) |
b076a3fd ZD |
641 | { |
642 | basic_block *body = get_loop_body_in_dom_order (loop); | |
643 | basic_block bb; | |
644 | unsigned i; | |
726a989a RB |
645 | gimple_stmt_iterator bsi; |
646 | gimple stmt; | |
647 | tree lhs, rhs; | |
b076a3fd ZD |
648 | struct mem_ref_group *refs = NULL; |
649 | ||
79f5e442 | 650 | *no_other_refs = true; |
db34470d | 651 | *ref_count = 0; |
79f5e442 | 652 | |
b076a3fd ZD |
653 | /* Scan the loop body in order, so that the former references precede the |
654 | later ones. */ | |
655 | for (i = 0; i < loop->num_nodes; i++) | |
656 | { | |
657 | bb = body[i]; | |
658 | if (bb->loop_father != loop) | |
659 | continue; | |
660 | ||
726a989a | 661 | for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) |
b076a3fd | 662 | { |
726a989a | 663 | stmt = gsi_stmt (bsi); |
79f5e442 | 664 | |
726a989a | 665 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
79f5e442 | 666 | { |
5006671f | 667 | if (gimple_vuse (stmt) |
726a989a RB |
668 | || (is_gimple_call (stmt) |
669 | && !(gimple_call_flags (stmt) & ECF_CONST))) | |
79f5e442 ZD |
670 | *no_other_refs = false; |
671 | continue; | |
672 | } | |
b076a3fd | 673 | |
726a989a RB |
674 | lhs = gimple_assign_lhs (stmt); |
675 | rhs = gimple_assign_rhs1 (stmt); | |
b076a3fd ZD |
676 | |
677 | if (REFERENCE_CLASS_P (rhs)) | |
db34470d | 678 | { |
79f5e442 ZD |
679 | *no_other_refs &= gather_memory_references_ref (loop, &refs, |
680 | rhs, false, stmt); | |
db34470d GS |
681 | *ref_count += 1; |
682 | } | |
b076a3fd | 683 | if (REFERENCE_CLASS_P (lhs)) |
db34470d | 684 | { |
79f5e442 ZD |
685 | *no_other_refs &= gather_memory_references_ref (loop, &refs, |
686 | lhs, true, stmt); | |
db34470d GS |
687 | *ref_count += 1; |
688 | } | |
b076a3fd ZD |
689 | } |
690 | } | |
691 | free (body); | |
692 | ||
693 | return refs; | |
694 | } | |
695 | ||
696 | /* Prune the prefetch candidate REF using the self-reuse. */ | |
697 | ||
698 | static void | |
699 | prune_ref_by_self_reuse (struct mem_ref *ref) | |
700 | { | |
81f32326 CB |
701 | HOST_WIDE_INT step; |
702 | bool backward; | |
703 | ||
704 | /* If the step size is non constant, we cannot calculate prefetch_mod. */ | |
705 | if (!cst_and_fits_in_hwi (ref->group->step)) | |
706 | return; | |
707 | ||
708 | step = int_cst_value (ref->group->step); | |
709 | ||
710 | backward = step < 0; | |
b076a3fd ZD |
711 | |
712 | if (step == 0) | |
713 | { | |
714 | /* Prefetch references to invariant address just once. */ | |
715 | ref->prefetch_before = 1; | |
716 | return; | |
717 | } | |
718 | ||
719 | if (backward) | |
720 | step = -step; | |
721 | ||
722 | if (step > PREFETCH_BLOCK) | |
723 | return; | |
724 | ||
725 | if ((backward && HAVE_BACKWARD_PREFETCH) | |
726 | || (!backward && HAVE_FORWARD_PREFETCH)) | |
727 | { | |
728 | ref->prefetch_before = 1; | |
729 | return; | |
730 | } | |
731 | ||
732 | ref->prefetch_mod = PREFETCH_BLOCK / step; | |
733 | } | |
734 | ||
735 | /* Divides X by BY, rounding down. */ | |
736 | ||
737 | static HOST_WIDE_INT | |
738 | ddown (HOST_WIDE_INT x, unsigned HOST_WIDE_INT by) | |
739 | { | |
740 | gcc_assert (by > 0); | |
741 | ||
742 | if (x >= 0) | |
743 | return x / by; | |
744 | else | |
745 | return (x + by - 1) / by; | |
746 | } | |
747 | ||
b8698a0f L |
748 | /* Given a CACHE_LINE_SIZE and two inductive memory references |
749 | with a common STEP greater than CACHE_LINE_SIZE and an address | |
750 | difference DELTA, compute the probability that they will fall | |
14e444c3 CF |
751 | in different cache lines. Return true if the computed miss rate |
752 | is not greater than the ACCEPTABLE_MISS_RATE. DISTINCT_ITERS is the | |
753 | number of distinct iterations after which the pattern repeats itself. | |
2c6dd136 GS |
754 | ALIGN_UNIT is the unit of alignment in bytes. */ |
755 | ||
14e444c3 CF |
756 | static bool |
757 | is_miss_rate_acceptable (unsigned HOST_WIDE_INT cache_line_size, | |
2c6dd136 GS |
758 | HOST_WIDE_INT step, HOST_WIDE_INT delta, |
759 | unsigned HOST_WIDE_INT distinct_iters, | |
760 | int align_unit) | |
761 | { | |
762 | unsigned align, iter; | |
14e444c3 | 763 | int total_positions, miss_positions, max_allowed_miss_positions; |
2c6dd136 GS |
764 | int address1, address2, cache_line1, cache_line2; |
765 | ||
a245c04b CF |
766 | /* It always misses if delta is greater than or equal to the cache |
767 | line size. */ | |
14e444c3 CF |
768 | if (delta >= (HOST_WIDE_INT) cache_line_size) |
769 | return false; | |
a245c04b | 770 | |
2c6dd136 | 771 | miss_positions = 0; |
14e444c3 CF |
772 | total_positions = (cache_line_size / align_unit) * distinct_iters; |
773 | max_allowed_miss_positions = (ACCEPTABLE_MISS_RATE * total_positions) / 1000; | |
b8698a0f | 774 | |
2c6dd136 GS |
775 | /* Iterate through all possible alignments of the first |
776 | memory reference within its cache line. */ | |
777 | for (align = 0; align < cache_line_size; align += align_unit) | |
778 | ||
779 | /* Iterate through all distinct iterations. */ | |
780 | for (iter = 0; iter < distinct_iters; iter++) | |
781 | { | |
782 | address1 = align + step * iter; | |
783 | address2 = address1 + delta; | |
784 | cache_line1 = address1 / cache_line_size; | |
785 | cache_line2 = address2 / cache_line_size; | |
2c6dd136 | 786 | if (cache_line1 != cache_line2) |
14e444c3 CF |
787 | { |
788 | miss_positions += 1; | |
789 | if (miss_positions > max_allowed_miss_positions) | |
790 | return false; | |
791 | } | |
2c6dd136 | 792 | } |
14e444c3 | 793 | return true; |
2c6dd136 GS |
794 | } |
795 | ||
b076a3fd ZD |
796 | /* Prune the prefetch candidate REF using the reuse with BY. |
797 | If BY_IS_BEFORE is true, BY is before REF in the loop. */ | |
798 | ||
799 | static void | |
800 | prune_ref_by_group_reuse (struct mem_ref *ref, struct mem_ref *by, | |
801 | bool by_is_before) | |
802 | { | |
81f32326 CB |
803 | HOST_WIDE_INT step; |
804 | bool backward; | |
b076a3fd ZD |
805 | HOST_WIDE_INT delta_r = ref->delta, delta_b = by->delta; |
806 | HOST_WIDE_INT delta = delta_b - delta_r; | |
807 | HOST_WIDE_INT hit_from; | |
808 | unsigned HOST_WIDE_INT prefetch_before, prefetch_block; | |
2c6dd136 GS |
809 | HOST_WIDE_INT reduced_step; |
810 | unsigned HOST_WIDE_INT reduced_prefetch_block; | |
811 | tree ref_type; | |
812 | int align_unit; | |
b076a3fd | 813 | |
81f32326 CB |
814 | /* If the step is non constant we cannot calculate prefetch_before. */ |
815 | if (!cst_and_fits_in_hwi (ref->group->step)) { | |
816 | return; | |
817 | } | |
818 | ||
819 | step = int_cst_value (ref->group->step); | |
820 | ||
821 | backward = step < 0; | |
822 | ||
823 | ||
b076a3fd ZD |
824 | if (delta == 0) |
825 | { | |
826 | /* If the references has the same address, only prefetch the | |
827 | former. */ | |
828 | if (by_is_before) | |
829 | ref->prefetch_before = 0; | |
b8698a0f | 830 | |
b076a3fd ZD |
831 | return; |
832 | } | |
833 | ||
834 | if (!step) | |
835 | { | |
836 | /* If the reference addresses are invariant and fall into the | |
837 | same cache line, prefetch just the first one. */ | |
838 | if (!by_is_before) | |
839 | return; | |
840 | ||
841 | if (ddown (ref->delta, PREFETCH_BLOCK) | |
842 | != ddown (by->delta, PREFETCH_BLOCK)) | |
843 | return; | |
844 | ||
845 | ref->prefetch_before = 0; | |
846 | return; | |
847 | } | |
848 | ||
849 | /* Only prune the reference that is behind in the array. */ | |
850 | if (backward) | |
851 | { | |
852 | if (delta > 0) | |
853 | return; | |
854 | ||
855 | /* Transform the data so that we may assume that the accesses | |
856 | are forward. */ | |
857 | delta = - delta; | |
858 | step = -step; | |
859 | delta_r = PREFETCH_BLOCK - 1 - delta_r; | |
860 | delta_b = PREFETCH_BLOCK - 1 - delta_b; | |
861 | } | |
862 | else | |
863 | { | |
864 | if (delta < 0) | |
865 | return; | |
866 | } | |
867 | ||
868 | /* Check whether the two references are likely to hit the same cache | |
869 | line, and how distant the iterations in that it occurs are from | |
870 | each other. */ | |
871 | ||
872 | if (step <= PREFETCH_BLOCK) | |
873 | { | |
874 | /* The accesses are sure to meet. Let us check when. */ | |
875 | hit_from = ddown (delta_b, PREFETCH_BLOCK) * PREFETCH_BLOCK; | |
876 | prefetch_before = (hit_from - delta_r + step - 1) / step; | |
877 | ||
57762e97 | 878 | /* Do not reduce prefetch_before if we meet beyond cache size. */ |
4c9cf7af | 879 | if (prefetch_before > absu_hwi (L2_CACHE_SIZE_BYTES / step)) |
57762e97 | 880 | prefetch_before = PREFETCH_ALL; |
b076a3fd ZD |
881 | if (prefetch_before < ref->prefetch_before) |
882 | ref->prefetch_before = prefetch_before; | |
883 | ||
884 | return; | |
885 | } | |
886 | ||
b8698a0f | 887 | /* A more complicated case with step > prefetch_block. First reduce |
2c6dd136 | 888 | the ratio between the step and the cache line size to its simplest |
b8698a0f L |
889 | terms. The resulting denominator will then represent the number of |
890 | distinct iterations after which each address will go back to its | |
891 | initial location within the cache line. This computation assumes | |
2c6dd136 | 892 | that PREFETCH_BLOCK is a power of two. */ |
b076a3fd | 893 | prefetch_block = PREFETCH_BLOCK; |
2c6dd136 GS |
894 | reduced_prefetch_block = prefetch_block; |
895 | reduced_step = step; | |
896 | while ((reduced_step & 1) == 0 | |
897 | && reduced_prefetch_block > 1) | |
b076a3fd | 898 | { |
2c6dd136 GS |
899 | reduced_step >>= 1; |
900 | reduced_prefetch_block >>= 1; | |
b076a3fd ZD |
901 | } |
902 | ||
b076a3fd ZD |
903 | prefetch_before = delta / step; |
904 | delta %= step; | |
2c6dd136 GS |
905 | ref_type = TREE_TYPE (ref->mem); |
906 | align_unit = TYPE_ALIGN (ref_type) / 8; | |
14e444c3 CF |
907 | if (is_miss_rate_acceptable (prefetch_block, step, delta, |
908 | reduced_prefetch_block, align_unit)) | |
b076a3fd | 909 | { |
57762e97 CB |
910 | /* Do not reduce prefetch_before if we meet beyond cache size. */ |
911 | if (prefetch_before > L2_CACHE_SIZE_BYTES / PREFETCH_BLOCK) | |
912 | prefetch_before = PREFETCH_ALL; | |
b076a3fd ZD |
913 | if (prefetch_before < ref->prefetch_before) |
914 | ref->prefetch_before = prefetch_before; | |
915 | ||
916 | return; | |
917 | } | |
918 | ||
919 | /* Try also the following iteration. */ | |
920 | prefetch_before++; | |
921 | delta = step - delta; | |
14e444c3 CF |
922 | if (is_miss_rate_acceptable (prefetch_block, step, delta, |
923 | reduced_prefetch_block, align_unit)) | |
b076a3fd ZD |
924 | { |
925 | if (prefetch_before < ref->prefetch_before) | |
926 | ref->prefetch_before = prefetch_before; | |
927 | ||
928 | return; | |
929 | } | |
930 | ||
931 | /* The ref probably does not reuse by. */ | |
932 | return; | |
933 | } | |
934 | ||
935 | /* Prune the prefetch candidate REF using the reuses with other references | |
936 | in REFS. */ | |
937 | ||
938 | static void | |
939 | prune_ref_by_reuse (struct mem_ref *ref, struct mem_ref *refs) | |
940 | { | |
941 | struct mem_ref *prune_by; | |
942 | bool before = true; | |
943 | ||
944 | prune_ref_by_self_reuse (ref); | |
945 | ||
946 | for (prune_by = refs; prune_by; prune_by = prune_by->next) | |
947 | { | |
948 | if (prune_by == ref) | |
949 | { | |
950 | before = false; | |
951 | continue; | |
952 | } | |
953 | ||
954 | if (!WRITE_CAN_USE_READ_PREFETCH | |
955 | && ref->write_p | |
956 | && !prune_by->write_p) | |
957 | continue; | |
958 | if (!READ_CAN_USE_WRITE_PREFETCH | |
959 | && !ref->write_p | |
960 | && prune_by->write_p) | |
961 | continue; | |
962 | ||
963 | prune_ref_by_group_reuse (ref, prune_by, before); | |
964 | } | |
965 | } | |
966 | ||
967 | /* Prune the prefetch candidates in GROUP using the reuse analysis. */ | |
968 | ||
969 | static void | |
970 | prune_group_by_reuse (struct mem_ref_group *group) | |
971 | { | |
972 | struct mem_ref *ref_pruned; | |
973 | ||
974 | for (ref_pruned = group->refs; ref_pruned; ref_pruned = ref_pruned->next) | |
975 | { | |
976 | prune_ref_by_reuse (ref_pruned, group->refs); | |
977 | ||
978 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
979 | { | |
980 | fprintf (dump_file, "Reference %p:", (void *) ref_pruned); | |
981 | ||
982 | if (ref_pruned->prefetch_before == PREFETCH_ALL | |
983 | && ref_pruned->prefetch_mod == 1) | |
984 | fprintf (dump_file, " no restrictions"); | |
985 | else if (ref_pruned->prefetch_before == 0) | |
986 | fprintf (dump_file, " do not prefetch"); | |
987 | else if (ref_pruned->prefetch_before <= ref_pruned->prefetch_mod) | |
988 | fprintf (dump_file, " prefetch once"); | |
989 | else | |
990 | { | |
991 | if (ref_pruned->prefetch_before != PREFETCH_ALL) | |
992 | { | |
993 | fprintf (dump_file, " prefetch before "); | |
994 | fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, | |
995 | ref_pruned->prefetch_before); | |
996 | } | |
997 | if (ref_pruned->prefetch_mod != 1) | |
998 | { | |
999 | fprintf (dump_file, " prefetch mod "); | |
1000 | fprintf (dump_file, HOST_WIDE_INT_PRINT_DEC, | |
1001 | ref_pruned->prefetch_mod); | |
1002 | } | |
1003 | } | |
1004 | fprintf (dump_file, "\n"); | |
1005 | } | |
1006 | } | |
1007 | } | |
1008 | ||
1009 | /* Prune the list of prefetch candidates GROUPS using the reuse analysis. */ | |
1010 | ||
1011 | static void | |
1012 | prune_by_reuse (struct mem_ref_group *groups) | |
1013 | { | |
1014 | for (; groups; groups = groups->next) | |
1015 | prune_group_by_reuse (groups); | |
1016 | } | |
1017 | ||
1018 | /* Returns true if we should issue prefetch for REF. */ | |
1019 | ||
1020 | static bool | |
1021 | should_issue_prefetch_p (struct mem_ref *ref) | |
1022 | { | |
1023 | /* For now do not issue prefetches for only first few of the | |
1024 | iterations. */ | |
1025 | if (ref->prefetch_before != PREFETCH_ALL) | |
a8beb3a7 CB |
1026 | { |
1027 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1028 | fprintf (dump_file, "Ignoring %p due to prefetch_before\n", | |
1029 | (void *) ref); | |
1030 | return false; | |
1031 | } | |
b076a3fd | 1032 | |
79f5e442 ZD |
1033 | /* Do not prefetch nontemporal stores. */ |
1034 | if (ref->storent_p) | |
a8beb3a7 CB |
1035 | { |
1036 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1037 | fprintf (dump_file, "Ignoring nontemporal store %p\n", (void *) ref); | |
1038 | return false; | |
1039 | } | |
79f5e442 | 1040 | |
b076a3fd ZD |
1041 | return true; |
1042 | } | |
1043 | ||
1044 | /* Decide which of the prefetch candidates in GROUPS to prefetch. | |
1045 | AHEAD is the number of iterations to prefetch ahead (which corresponds | |
1046 | to the number of simultaneous instances of one prefetch running at a | |
1047 | time). UNROLL_FACTOR is the factor by that the loop is going to be | |
1048 | unrolled. Returns true if there is anything to prefetch. */ | |
1049 | ||
1050 | static bool | |
1051 | schedule_prefetches (struct mem_ref_group *groups, unsigned unroll_factor, | |
1052 | unsigned ahead) | |
1053 | { | |
911b3fdb ZD |
1054 | unsigned remaining_prefetch_slots, n_prefetches, prefetch_slots; |
1055 | unsigned slots_per_prefetch; | |
b076a3fd ZD |
1056 | struct mem_ref *ref; |
1057 | bool any = false; | |
1058 | ||
911b3fdb ZD |
1059 | /* At most SIMULTANEOUS_PREFETCHES should be running at the same time. */ |
1060 | remaining_prefetch_slots = SIMULTANEOUS_PREFETCHES; | |
b076a3fd | 1061 | |
911b3fdb ZD |
1062 | /* The prefetch will run for AHEAD iterations of the original loop, i.e., |
1063 | AHEAD / UNROLL_FACTOR iterations of the unrolled loop. In each iteration, | |
1064 | it will need a prefetch slot. */ | |
1065 | slots_per_prefetch = (ahead + unroll_factor / 2) / unroll_factor; | |
b076a3fd | 1066 | if (dump_file && (dump_flags & TDF_DETAILS)) |
911b3fdb ZD |
1067 | fprintf (dump_file, "Each prefetch instruction takes %u prefetch slots.\n", |
1068 | slots_per_prefetch); | |
b076a3fd ZD |
1069 | |
1070 | /* For now we just take memory references one by one and issue | |
1071 | prefetches for as many as possible. The groups are sorted | |
1072 | starting with the largest step, since the references with | |
c0220ea4 | 1073 | large step are more likely to cause many cache misses. */ |
b076a3fd ZD |
1074 | |
1075 | for (; groups; groups = groups->next) | |
1076 | for (ref = groups->refs; ref; ref = ref->next) | |
1077 | { | |
1078 | if (!should_issue_prefetch_p (ref)) | |
1079 | continue; | |
1080 | ||
8532678c CF |
1081 | /* The loop is far from being sufficiently unrolled for this |
1082 | prefetch. Do not generate prefetch to avoid many redudant | |
1083 | prefetches. */ | |
1084 | if (ref->prefetch_mod / unroll_factor > PREFETCH_MOD_TO_UNROLL_FACTOR_RATIO) | |
1085 | continue; | |
1086 | ||
911b3fdb ZD |
1087 | /* If we need to prefetch the reference each PREFETCH_MOD iterations, |
1088 | and we unroll the loop UNROLL_FACTOR times, we need to insert | |
1089 | ceil (UNROLL_FACTOR / PREFETCH_MOD) instructions in each | |
1090 | iteration. */ | |
b076a3fd ZD |
1091 | n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) |
1092 | / ref->prefetch_mod); | |
911b3fdb ZD |
1093 | prefetch_slots = n_prefetches * slots_per_prefetch; |
1094 | ||
1095 | /* If more than half of the prefetches would be lost anyway, do not | |
1096 | issue the prefetch. */ | |
1097 | if (2 * remaining_prefetch_slots < prefetch_slots) | |
1098 | continue; | |
1099 | ||
1100 | ref->issue_prefetch_p = true; | |
b076a3fd | 1101 | |
911b3fdb ZD |
1102 | if (remaining_prefetch_slots <= prefetch_slots) |
1103 | return true; | |
1104 | remaining_prefetch_slots -= prefetch_slots; | |
b076a3fd ZD |
1105 | any = true; |
1106 | } | |
1107 | ||
1108 | return any; | |
1109 | } | |
1110 | ||
d5058523 CF |
1111 | /* Return TRUE if no prefetch is going to be generated in the given |
1112 | GROUPS. */ | |
1113 | ||
1114 | static bool | |
1115 | nothing_to_prefetch_p (struct mem_ref_group *groups) | |
1116 | { | |
1117 | struct mem_ref *ref; | |
1118 | ||
1119 | for (; groups; groups = groups->next) | |
1120 | for (ref = groups->refs; ref; ref = ref->next) | |
1121 | if (should_issue_prefetch_p (ref)) | |
1122 | return false; | |
1123 | ||
1124 | return true; | |
1125 | } | |
1126 | ||
1127 | /* Estimate the number of prefetches in the given GROUPS. | |
1128 | UNROLL_FACTOR is the factor by which LOOP was unrolled. */ | |
b076a3fd | 1129 | |
db34470d | 1130 | static int |
d5058523 | 1131 | estimate_prefetch_count (struct mem_ref_group *groups, unsigned unroll_factor) |
b076a3fd ZD |
1132 | { |
1133 | struct mem_ref *ref; | |
d5058523 | 1134 | unsigned n_prefetches; |
db34470d | 1135 | int prefetch_count = 0; |
b076a3fd ZD |
1136 | |
1137 | for (; groups; groups = groups->next) | |
1138 | for (ref = groups->refs; ref; ref = ref->next) | |
1139 | if (should_issue_prefetch_p (ref)) | |
d5058523 CF |
1140 | { |
1141 | n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) | |
1142 | / ref->prefetch_mod); | |
1143 | prefetch_count += n_prefetches; | |
1144 | } | |
b076a3fd | 1145 | |
db34470d | 1146 | return prefetch_count; |
b076a3fd ZD |
1147 | } |
1148 | ||
1149 | /* Issue prefetches for the reference REF into loop as decided before. | |
1150 | HEAD is the number of iterations to prefetch ahead. UNROLL_FACTOR | |
917f1b7e | 1151 | is the factor by which LOOP was unrolled. */ |
b076a3fd ZD |
1152 | |
1153 | static void | |
1154 | issue_prefetch_ref (struct mem_ref *ref, unsigned unroll_factor, unsigned ahead) | |
1155 | { | |
1156 | HOST_WIDE_INT delta; | |
81f32326 | 1157 | tree addr, addr_base, write_p, local, forward; |
538dd0b7 | 1158 | gcall *prefetch; |
726a989a | 1159 | gimple_stmt_iterator bsi; |
b076a3fd | 1160 | unsigned n_prefetches, ap; |
5417e022 | 1161 | bool nontemporal = ref->reuse_distance >= L2_CACHE_SIZE_BYTES; |
b076a3fd ZD |
1162 | |
1163 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
5417e022 ZD |
1164 | fprintf (dump_file, "Issued%s prefetch for %p.\n", |
1165 | nontemporal ? " nontemporal" : "", | |
1166 | (void *) ref); | |
b076a3fd | 1167 | |
726a989a | 1168 | bsi = gsi_for_stmt (ref->stmt); |
b076a3fd ZD |
1169 | |
1170 | n_prefetches = ((unroll_factor + ref->prefetch_mod - 1) | |
1171 | / ref->prefetch_mod); | |
1172 | addr_base = build_fold_addr_expr_with_type (ref->mem, ptr_type_node); | |
726a989a RB |
1173 | addr_base = force_gimple_operand_gsi (&bsi, unshare_expr (addr_base), |
1174 | true, NULL, true, GSI_SAME_STMT); | |
911b3fdb | 1175 | write_p = ref->write_p ? integer_one_node : integer_zero_node; |
9a9d280e | 1176 | local = nontemporal ? integer_zero_node : integer_three_node; |
b076a3fd ZD |
1177 | |
1178 | for (ap = 0; ap < n_prefetches; ap++) | |
1179 | { | |
81f32326 CB |
1180 | if (cst_and_fits_in_hwi (ref->group->step)) |
1181 | { | |
1182 | /* Determine the address to prefetch. */ | |
1183 | delta = (ahead + ap * ref->prefetch_mod) * | |
1184 | int_cst_value (ref->group->step); | |
5d49b6a7 | 1185 | addr = fold_build_pointer_plus_hwi (addr_base, delta); |
81f32326 CB |
1186 | addr = force_gimple_operand_gsi (&bsi, unshare_expr (addr), true, NULL, |
1187 | true, GSI_SAME_STMT); | |
1188 | } | |
1189 | else | |
1190 | { | |
1191 | /* The step size is non-constant but loop-invariant. We use the | |
1192 | heuristic to simply prefetch ahead iterations ahead. */ | |
1193 | forward = fold_build2 (MULT_EXPR, sizetype, | |
1194 | fold_convert (sizetype, ref->group->step), | |
1195 | fold_convert (sizetype, size_int (ahead))); | |
5d49b6a7 | 1196 | addr = fold_build_pointer_plus (addr_base, forward); |
81f32326 CB |
1197 | addr = force_gimple_operand_gsi (&bsi, unshare_expr (addr), true, |
1198 | NULL, true, GSI_SAME_STMT); | |
1199 | } | |
b076a3fd | 1200 | /* Create the prefetch instruction. */ |
e79983f4 | 1201 | prefetch = gimple_build_call (builtin_decl_explicit (BUILT_IN_PREFETCH), |
726a989a RB |
1202 | 3, addr, write_p, local); |
1203 | gsi_insert_before (&bsi, prefetch, GSI_SAME_STMT); | |
b076a3fd ZD |
1204 | } |
1205 | } | |
1206 | ||
1207 | /* Issue prefetches for the references in GROUPS into loop as decided before. | |
1208 | HEAD is the number of iterations to prefetch ahead. UNROLL_FACTOR is the | |
1209 | factor by that LOOP was unrolled. */ | |
1210 | ||
1211 | static void | |
1212 | issue_prefetches (struct mem_ref_group *groups, | |
1213 | unsigned unroll_factor, unsigned ahead) | |
1214 | { | |
1215 | struct mem_ref *ref; | |
1216 | ||
1217 | for (; groups; groups = groups->next) | |
1218 | for (ref = groups->refs; ref; ref = ref->next) | |
1219 | if (ref->issue_prefetch_p) | |
1220 | issue_prefetch_ref (ref, unroll_factor, ahead); | |
1221 | } | |
1222 | ||
79f5e442 ZD |
1223 | /* Returns true if REF is a memory write for that a nontemporal store insn |
1224 | can be used. */ | |
1225 | ||
1226 | static bool | |
1227 | nontemporal_store_p (struct mem_ref *ref) | |
1228 | { | |
ef4bddc2 | 1229 | machine_mode mode; |
79f5e442 ZD |
1230 | enum insn_code code; |
1231 | ||
1232 | /* REF must be a write that is not reused. We require it to be independent | |
1233 | on all other memory references in the loop, as the nontemporal stores may | |
1234 | be reordered with respect to other memory references. */ | |
1235 | if (!ref->write_p | |
1236 | || !ref->independent_p | |
1237 | || ref->reuse_distance < L2_CACHE_SIZE_BYTES) | |
1238 | return false; | |
1239 | ||
1240 | /* Check that we have the storent instruction for the mode. */ | |
1241 | mode = TYPE_MODE (TREE_TYPE (ref->mem)); | |
1242 | if (mode == BLKmode) | |
1243 | return false; | |
1244 | ||
947131ba | 1245 | code = optab_handler (storent_optab, mode); |
79f5e442 ZD |
1246 | return code != CODE_FOR_nothing; |
1247 | } | |
1248 | ||
1249 | /* If REF is a nontemporal store, we mark the corresponding modify statement | |
1250 | and return true. Otherwise, we return false. */ | |
1251 | ||
1252 | static bool | |
1253 | mark_nontemporal_store (struct mem_ref *ref) | |
1254 | { | |
1255 | if (!nontemporal_store_p (ref)) | |
1256 | return false; | |
1257 | ||
1258 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1259 | fprintf (dump_file, "Marked reference %p as a nontemporal store.\n", | |
1260 | (void *) ref); | |
1261 | ||
726a989a | 1262 | gimple_assign_set_nontemporal_move (ref->stmt, true); |
79f5e442 ZD |
1263 | ref->storent_p = true; |
1264 | ||
1265 | return true; | |
1266 | } | |
1267 | ||
1268 | /* Issue a memory fence instruction after LOOP. */ | |
1269 | ||
1270 | static void | |
1271 | emit_mfence_after_loop (struct loop *loop) | |
1272 | { | |
9771b263 | 1273 | vec<edge> exits = get_loop_exit_edges (loop); |
79f5e442 | 1274 | edge exit; |
538dd0b7 | 1275 | gcall *call; |
726a989a | 1276 | gimple_stmt_iterator bsi; |
79f5e442 ZD |
1277 | unsigned i; |
1278 | ||
9771b263 | 1279 | FOR_EACH_VEC_ELT (exits, i, exit) |
79f5e442 | 1280 | { |
726a989a | 1281 | call = gimple_build_call (FENCE_FOLLOWING_MOVNT, 0); |
79f5e442 ZD |
1282 | |
1283 | if (!single_pred_p (exit->dest) | |
1284 | /* If possible, we prefer not to insert the fence on other paths | |
1285 | in cfg. */ | |
1286 | && !(exit->flags & EDGE_ABNORMAL)) | |
1287 | split_loop_exit_edge (exit); | |
726a989a | 1288 | bsi = gsi_after_labels (exit->dest); |
79f5e442 | 1289 | |
726a989a | 1290 | gsi_insert_before (&bsi, call, GSI_NEW_STMT); |
79f5e442 ZD |
1291 | } |
1292 | ||
9771b263 | 1293 | exits.release (); |
79f5e442 ZD |
1294 | update_ssa (TODO_update_ssa_only_virtuals); |
1295 | } | |
1296 | ||
1297 | /* Returns true if we can use storent in loop, false otherwise. */ | |
1298 | ||
1299 | static bool | |
1300 | may_use_storent_in_loop_p (struct loop *loop) | |
1301 | { | |
1302 | bool ret = true; | |
1303 | ||
1304 | if (loop->inner != NULL) | |
1305 | return false; | |
1306 | ||
1307 | /* If we must issue a mfence insn after using storent, check that there | |
1308 | is a suitable place for it at each of the loop exits. */ | |
1309 | if (FENCE_FOLLOWING_MOVNT != NULL_TREE) | |
1310 | { | |
9771b263 | 1311 | vec<edge> exits = get_loop_exit_edges (loop); |
79f5e442 ZD |
1312 | unsigned i; |
1313 | edge exit; | |
1314 | ||
9771b263 | 1315 | FOR_EACH_VEC_ELT (exits, i, exit) |
79f5e442 | 1316 | if ((exit->flags & EDGE_ABNORMAL) |
fefa31b5 | 1317 | && exit->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
79f5e442 ZD |
1318 | ret = false; |
1319 | ||
9771b263 | 1320 | exits.release (); |
79f5e442 ZD |
1321 | } |
1322 | ||
1323 | return ret; | |
1324 | } | |
1325 | ||
1326 | /* Marks nontemporal stores in LOOP. GROUPS contains the description of memory | |
1327 | references in the loop. */ | |
1328 | ||
1329 | static void | |
1330 | mark_nontemporal_stores (struct loop *loop, struct mem_ref_group *groups) | |
1331 | { | |
1332 | struct mem_ref *ref; | |
1333 | bool any = false; | |
1334 | ||
1335 | if (!may_use_storent_in_loop_p (loop)) | |
1336 | return; | |
1337 | ||
1338 | for (; groups; groups = groups->next) | |
1339 | for (ref = groups->refs; ref; ref = ref->next) | |
1340 | any |= mark_nontemporal_store (ref); | |
1341 | ||
1342 | if (any && FENCE_FOLLOWING_MOVNT != NULL_TREE) | |
1343 | emit_mfence_after_loop (loop); | |
1344 | } | |
1345 | ||
b076a3fd ZD |
1346 | /* Determines whether we can profitably unroll LOOP FACTOR times, and if |
1347 | this is the case, fill in DESC by the description of number of | |
1348 | iterations. */ | |
1349 | ||
1350 | static bool | |
1351 | should_unroll_loop_p (struct loop *loop, struct tree_niter_desc *desc, | |
1352 | unsigned factor) | |
1353 | { | |
1354 | if (!can_unroll_loop_p (loop, factor, desc)) | |
1355 | return false; | |
1356 | ||
1357 | /* We only consider loops without control flow for unrolling. This is not | |
1358 | a hard restriction -- tree_unroll_loop works with arbitrary loops | |
1359 | as well; but the unrolling/prefetching is usually more profitable for | |
1360 | loops consisting of a single basic block, and we want to limit the | |
1361 | code growth. */ | |
1362 | if (loop->num_nodes > 2) | |
1363 | return false; | |
1364 | ||
1365 | return true; | |
1366 | } | |
1367 | ||
1368 | /* Determine the coefficient by that unroll LOOP, from the information | |
1369 | contained in the list of memory references REFS. Description of | |
2711355f ZD |
1370 | umber of iterations of LOOP is stored to DESC. NINSNS is the number of |
1371 | insns of the LOOP. EST_NITER is the estimated number of iterations of | |
1372 | the loop, or -1 if no estimate is available. */ | |
b076a3fd ZD |
1373 | |
1374 | static unsigned | |
1375 | determine_unroll_factor (struct loop *loop, struct mem_ref_group *refs, | |
2711355f ZD |
1376 | unsigned ninsns, struct tree_niter_desc *desc, |
1377 | HOST_WIDE_INT est_niter) | |
b076a3fd | 1378 | { |
911b3fdb ZD |
1379 | unsigned upper_bound; |
1380 | unsigned nfactor, factor, mod_constraint; | |
b076a3fd ZD |
1381 | struct mem_ref_group *agp; |
1382 | struct mem_ref *ref; | |
1383 | ||
911b3fdb ZD |
1384 | /* First check whether the loop is not too large to unroll. We ignore |
1385 | PARAM_MAX_UNROLL_TIMES, because for small loops, it prevented us | |
1386 | from unrolling them enough to make exactly one cache line covered by each | |
1387 | iteration. Also, the goal of PARAM_MAX_UNROLL_TIMES is to prevent | |
1388 | us from unrolling the loops too many times in cases where we only expect | |
1389 | gains from better scheduling and decreasing loop overhead, which is not | |
1390 | the case here. */ | |
1391 | upper_bound = PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS) / ninsns; | |
2711355f ZD |
1392 | |
1393 | /* If we unrolled the loop more times than it iterates, the unrolled version | |
1394 | of the loop would be never entered. */ | |
1395 | if (est_niter >= 0 && est_niter < (HOST_WIDE_INT) upper_bound) | |
1396 | upper_bound = est_niter; | |
1397 | ||
911b3fdb | 1398 | if (upper_bound <= 1) |
b076a3fd ZD |
1399 | return 1; |
1400 | ||
911b3fdb ZD |
1401 | /* Choose the factor so that we may prefetch each cache just once, |
1402 | but bound the unrolling by UPPER_BOUND. */ | |
1403 | factor = 1; | |
b076a3fd ZD |
1404 | for (agp = refs; agp; agp = agp->next) |
1405 | for (ref = agp->refs; ref; ref = ref->next) | |
911b3fdb ZD |
1406 | if (should_issue_prefetch_p (ref)) |
1407 | { | |
1408 | mod_constraint = ref->prefetch_mod; | |
1409 | nfactor = least_common_multiple (mod_constraint, factor); | |
1410 | if (nfactor <= upper_bound) | |
1411 | factor = nfactor; | |
1412 | } | |
b076a3fd ZD |
1413 | |
1414 | if (!should_unroll_loop_p (loop, desc, factor)) | |
1415 | return 1; | |
1416 | ||
1417 | return factor; | |
1418 | } | |
1419 | ||
5417e022 ZD |
1420 | /* Returns the total volume of the memory references REFS, taking into account |
1421 | reuses in the innermost loop and cache line size. TODO -- we should also | |
1422 | take into account reuses across the iterations of the loops in the loop | |
1423 | nest. */ | |
1424 | ||
1425 | static unsigned | |
1426 | volume_of_references (struct mem_ref_group *refs) | |
1427 | { | |
1428 | unsigned volume = 0; | |
1429 | struct mem_ref_group *gr; | |
1430 | struct mem_ref *ref; | |
1431 | ||
1432 | for (gr = refs; gr; gr = gr->next) | |
1433 | for (ref = gr->refs; ref; ref = ref->next) | |
1434 | { | |
1435 | /* Almost always reuses another value? */ | |
1436 | if (ref->prefetch_before != PREFETCH_ALL) | |
1437 | continue; | |
1438 | ||
1439 | /* If several iterations access the same cache line, use the size of | |
1440 | the line divided by this number. Otherwise, a cache line is | |
1441 | accessed in each iteration. TODO -- in the latter case, we should | |
1442 | take the size of the reference into account, rounding it up on cache | |
1443 | line size multiple. */ | |
1444 | volume += L1_CACHE_LINE_SIZE / ref->prefetch_mod; | |
1445 | } | |
1446 | return volume; | |
1447 | } | |
1448 | ||
1449 | /* Returns the volume of memory references accessed across VEC iterations of | |
1450 | loops, whose sizes are described in the LOOP_SIZES array. N is the number | |
1451 | of the loops in the nest (length of VEC and LOOP_SIZES vectors). */ | |
1452 | ||
1453 | static unsigned | |
1454 | volume_of_dist_vector (lambda_vector vec, unsigned *loop_sizes, unsigned n) | |
1455 | { | |
1456 | unsigned i; | |
1457 | ||
1458 | for (i = 0; i < n; i++) | |
1459 | if (vec[i] != 0) | |
1460 | break; | |
1461 | ||
1462 | if (i == n) | |
1463 | return 0; | |
1464 | ||
1465 | gcc_assert (vec[i] > 0); | |
1466 | ||
1467 | /* We ignore the parts of the distance vector in subloops, since usually | |
1468 | the numbers of iterations are much smaller. */ | |
1469 | return loop_sizes[i] * vec[i]; | |
1470 | } | |
1471 | ||
1472 | /* Add the steps of ACCESS_FN multiplied by STRIDE to the array STRIDE | |
1473 | at the position corresponding to the loop of the step. N is the depth | |
1474 | of the considered loop nest, and, LOOP is its innermost loop. */ | |
1475 | ||
1476 | static void | |
1477 | add_subscript_strides (tree access_fn, unsigned stride, | |
1478 | HOST_WIDE_INT *strides, unsigned n, struct loop *loop) | |
1479 | { | |
1480 | struct loop *aloop; | |
1481 | tree step; | |
1482 | HOST_WIDE_INT astep; | |
1483 | unsigned min_depth = loop_depth (loop) - n; | |
1484 | ||
1485 | while (TREE_CODE (access_fn) == POLYNOMIAL_CHREC) | |
1486 | { | |
1487 | aloop = get_chrec_loop (access_fn); | |
1488 | step = CHREC_RIGHT (access_fn); | |
1489 | access_fn = CHREC_LEFT (access_fn); | |
1490 | ||
1491 | if ((unsigned) loop_depth (aloop) <= min_depth) | |
1492 | continue; | |
1493 | ||
9541ffee | 1494 | if (tree_fits_shwi_p (step)) |
9439e9a1 | 1495 | astep = tree_to_shwi (step); |
5417e022 ZD |
1496 | else |
1497 | astep = L1_CACHE_LINE_SIZE; | |
1498 | ||
1499 | strides[n - 1 - loop_depth (loop) + loop_depth (aloop)] += astep * stride; | |
1500 | ||
1501 | } | |
1502 | } | |
1503 | ||
1504 | /* Returns the volume of memory references accessed between two consecutive | |
1505 | self-reuses of the reference DR. We consider the subscripts of DR in N | |
1506 | loops, and LOOP_SIZES contains the volumes of accesses in each of the | |
1507 | loops. LOOP is the innermost loop of the current loop nest. */ | |
1508 | ||
1509 | static unsigned | |
1510 | self_reuse_distance (data_reference_p dr, unsigned *loop_sizes, unsigned n, | |
1511 | struct loop *loop) | |
1512 | { | |
1513 | tree stride, access_fn; | |
1514 | HOST_WIDE_INT *strides, astride; | |
9771b263 | 1515 | vec<tree> access_fns; |
5417e022 ZD |
1516 | tree ref = DR_REF (dr); |
1517 | unsigned i, ret = ~0u; | |
1518 | ||
1519 | /* In the following example: | |
1520 | ||
1521 | for (i = 0; i < N; i++) | |
1522 | for (j = 0; j < N; j++) | |
1523 | use (a[j][i]); | |
1524 | the same cache line is accessed each N steps (except if the change from | |
1525 | i to i + 1 crosses the boundary of the cache line). Thus, for self-reuse, | |
1526 | we cannot rely purely on the results of the data dependence analysis. | |
1527 | ||
1528 | Instead, we compute the stride of the reference in each loop, and consider | |
1529 | the innermost loop in that the stride is less than cache size. */ | |
1530 | ||
1531 | strides = XCNEWVEC (HOST_WIDE_INT, n); | |
1532 | access_fns = DR_ACCESS_FNS (dr); | |
1533 | ||
9771b263 | 1534 | FOR_EACH_VEC_ELT (access_fns, i, access_fn) |
5417e022 ZD |
1535 | { |
1536 | /* Keep track of the reference corresponding to the subscript, so that we | |
1537 | know its stride. */ | |
1538 | while (handled_component_p (ref) && TREE_CODE (ref) != ARRAY_REF) | |
1539 | ref = TREE_OPERAND (ref, 0); | |
b8698a0f | 1540 | |
5417e022 ZD |
1541 | if (TREE_CODE (ref) == ARRAY_REF) |
1542 | { | |
1543 | stride = TYPE_SIZE_UNIT (TREE_TYPE (ref)); | |
cc269bb6 | 1544 | if (tree_fits_uhwi_p (stride)) |
ae7e9ddd | 1545 | astride = tree_to_uhwi (stride); |
5417e022 ZD |
1546 | else |
1547 | astride = L1_CACHE_LINE_SIZE; | |
1548 | ||
1549 | ref = TREE_OPERAND (ref, 0); | |
1550 | } | |
1551 | else | |
1552 | astride = 1; | |
1553 | ||
1554 | add_subscript_strides (access_fn, astride, strides, n, loop); | |
1555 | } | |
1556 | ||
1557 | for (i = n; i-- > 0; ) | |
1558 | { | |
1559 | unsigned HOST_WIDE_INT s; | |
1560 | ||
1561 | s = strides[i] < 0 ? -strides[i] : strides[i]; | |
1562 | ||
1563 | if (s < (unsigned) L1_CACHE_LINE_SIZE | |
1564 | && (loop_sizes[i] | |
1565 | > (unsigned) (L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION))) | |
1566 | { | |
1567 | ret = loop_sizes[i]; | |
1568 | break; | |
1569 | } | |
1570 | } | |
1571 | ||
1572 | free (strides); | |
1573 | return ret; | |
1574 | } | |
1575 | ||
1576 | /* Determines the distance till the first reuse of each reference in REFS | |
79f5e442 | 1577 | in the loop nest of LOOP. NO_OTHER_REFS is true if there are no other |
1e373390 | 1578 | memory references in the loop. Return false if the analysis fails. */ |
5417e022 | 1579 | |
1e373390 | 1580 | static bool |
79f5e442 ZD |
1581 | determine_loop_nest_reuse (struct loop *loop, struct mem_ref_group *refs, |
1582 | bool no_other_refs) | |
5417e022 ZD |
1583 | { |
1584 | struct loop *nest, *aloop; | |
6e1aa848 DN |
1585 | vec<data_reference_p> datarefs = vNULL; |
1586 | vec<ddr_p> dependences = vNULL; | |
5417e022 | 1587 | struct mem_ref_group *gr; |
79f5e442 | 1588 | struct mem_ref *ref, *refb; |
6e1aa848 | 1589 | vec<loop_p> vloops = vNULL; |
5417e022 ZD |
1590 | unsigned *loop_data_size; |
1591 | unsigned i, j, n; | |
1592 | unsigned volume, dist, adist; | |
1593 | HOST_WIDE_INT vol; | |
1594 | data_reference_p dr; | |
1595 | ddr_p dep; | |
1596 | ||
1597 | if (loop->inner) | |
1e373390 | 1598 | return true; |
5417e022 ZD |
1599 | |
1600 | /* Find the outermost loop of the loop nest of loop (we require that | |
1601 | there are no sibling loops inside the nest). */ | |
1602 | nest = loop; | |
1603 | while (1) | |
1604 | { | |
1605 | aloop = loop_outer (nest); | |
1606 | ||
1607 | if (aloop == current_loops->tree_root | |
1608 | || aloop->inner->next) | |
1609 | break; | |
1610 | ||
1611 | nest = aloop; | |
1612 | } | |
1613 | ||
1614 | /* For each loop, determine the amount of data accessed in each iteration. | |
1615 | We use this to estimate whether the reference is evicted from the | |
1616 | cache before its reuse. */ | |
1617 | find_loop_nest (nest, &vloops); | |
9771b263 | 1618 | n = vloops.length (); |
5417e022 ZD |
1619 | loop_data_size = XNEWVEC (unsigned, n); |
1620 | volume = volume_of_references (refs); | |
1621 | i = n; | |
1622 | while (i-- != 0) | |
1623 | { | |
1624 | loop_data_size[i] = volume; | |
1625 | /* Bound the volume by the L2 cache size, since above this bound, | |
1626 | all dependence distances are equivalent. */ | |
1627 | if (volume > L2_CACHE_SIZE_BYTES) | |
1628 | continue; | |
1629 | ||
9771b263 | 1630 | aloop = vloops[i]; |
652c4c71 | 1631 | vol = estimated_stmt_executions_int (aloop); |
e5b332cd | 1632 | if (vol == -1) |
5417e022 ZD |
1633 | vol = expected_loop_iterations (aloop); |
1634 | volume *= vol; | |
1635 | } | |
1636 | ||
1637 | /* Prepare the references in the form suitable for data dependence | |
0d52bcc1 | 1638 | analysis. We ignore unanalyzable data references (the results |
5417e022 ZD |
1639 | are used just as a heuristics to estimate temporality of the |
1640 | references, hence we do not need to worry about correctness). */ | |
1641 | for (gr = refs; gr; gr = gr->next) | |
1642 | for (ref = gr->refs; ref; ref = ref->next) | |
1643 | { | |
5c640e29 SP |
1644 | dr = create_data_ref (nest, loop_containing_stmt (ref->stmt), |
1645 | ref->mem, ref->stmt, !ref->write_p); | |
5417e022 ZD |
1646 | |
1647 | if (dr) | |
1648 | { | |
1649 | ref->reuse_distance = volume; | |
1650 | dr->aux = ref; | |
9771b263 | 1651 | datarefs.safe_push (dr); |
5417e022 | 1652 | } |
79f5e442 ZD |
1653 | else |
1654 | no_other_refs = false; | |
5417e022 ZD |
1655 | } |
1656 | ||
9771b263 | 1657 | FOR_EACH_VEC_ELT (datarefs, i, dr) |
5417e022 ZD |
1658 | { |
1659 | dist = self_reuse_distance (dr, loop_data_size, n, loop); | |
3d9a9f94 | 1660 | ref = (struct mem_ref *) dr->aux; |
5417e022 ZD |
1661 | if (ref->reuse_distance > dist) |
1662 | ref->reuse_distance = dist; | |
79f5e442 ZD |
1663 | |
1664 | if (no_other_refs) | |
1665 | ref->independent_p = true; | |
5417e022 ZD |
1666 | } |
1667 | ||
1e373390 RG |
1668 | if (!compute_all_dependences (datarefs, &dependences, vloops, true)) |
1669 | return false; | |
5417e022 | 1670 | |
9771b263 | 1671 | FOR_EACH_VEC_ELT (dependences, i, dep) |
5417e022 ZD |
1672 | { |
1673 | if (DDR_ARE_DEPENDENT (dep) == chrec_known) | |
1674 | continue; | |
1675 | ||
3d9a9f94 KG |
1676 | ref = (struct mem_ref *) DDR_A (dep)->aux; |
1677 | refb = (struct mem_ref *) DDR_B (dep)->aux; | |
79f5e442 | 1678 | |
5417e022 ZD |
1679 | if (DDR_ARE_DEPENDENT (dep) == chrec_dont_know |
1680 | || DDR_NUM_DIST_VECTS (dep) == 0) | |
1681 | { | |
0d52bcc1 | 1682 | /* If the dependence cannot be analyzed, assume that there might be |
5417e022 ZD |
1683 | a reuse. */ |
1684 | dist = 0; | |
b8698a0f | 1685 | |
79f5e442 ZD |
1686 | ref->independent_p = false; |
1687 | refb->independent_p = false; | |
5417e022 ZD |
1688 | } |
1689 | else | |
1690 | { | |
0d52bcc1 | 1691 | /* The distance vectors are normalized to be always lexicographically |
5417e022 ZD |
1692 | positive, hence we cannot tell just from them whether DDR_A comes |
1693 | before DDR_B or vice versa. However, it is not important, | |
1694 | anyway -- if DDR_A is close to DDR_B, then it is either reused in | |
1695 | DDR_B (and it is not nontemporal), or it reuses the value of DDR_B | |
1696 | in cache (and marking it as nontemporal would not affect | |
1697 | anything). */ | |
1698 | ||
1699 | dist = volume; | |
1700 | for (j = 0; j < DDR_NUM_DIST_VECTS (dep); j++) | |
1701 | { | |
1702 | adist = volume_of_dist_vector (DDR_DIST_VECT (dep, j), | |
1703 | loop_data_size, n); | |
1704 | ||
79f5e442 ZD |
1705 | /* If this is a dependence in the innermost loop (i.e., the |
1706 | distances in all superloops are zero) and it is not | |
1707 | the trivial self-dependence with distance zero, record that | |
1708 | the references are not completely independent. */ | |
1709 | if (lambda_vector_zerop (DDR_DIST_VECT (dep, j), n - 1) | |
1710 | && (ref != refb | |
1711 | || DDR_DIST_VECT (dep, j)[n-1] != 0)) | |
1712 | { | |
1713 | ref->independent_p = false; | |
1714 | refb->independent_p = false; | |
1715 | } | |
1716 | ||
5417e022 ZD |
1717 | /* Ignore accesses closer than |
1718 | L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION, | |
1719 | so that we use nontemporal prefetches e.g. if single memory | |
1720 | location is accessed several times in a single iteration of | |
1721 | the loop. */ | |
1722 | if (adist < L1_CACHE_SIZE_BYTES / NONTEMPORAL_FRACTION) | |
1723 | continue; | |
1724 | ||
1725 | if (adist < dist) | |
1726 | dist = adist; | |
1727 | } | |
1728 | } | |
1729 | ||
5417e022 ZD |
1730 | if (ref->reuse_distance > dist) |
1731 | ref->reuse_distance = dist; | |
79f5e442 ZD |
1732 | if (refb->reuse_distance > dist) |
1733 | refb->reuse_distance = dist; | |
5417e022 ZD |
1734 | } |
1735 | ||
1736 | free_dependence_relations (dependences); | |
1737 | free_data_refs (datarefs); | |
1738 | free (loop_data_size); | |
1739 | ||
1740 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1741 | { | |
1742 | fprintf (dump_file, "Reuse distances:\n"); | |
1743 | for (gr = refs; gr; gr = gr->next) | |
1744 | for (ref = gr->refs; ref; ref = ref->next) | |
1745 | fprintf (dump_file, " ref %p distance %u\n", | |
1746 | (void *) ref, ref->reuse_distance); | |
1747 | } | |
1e373390 RG |
1748 | |
1749 | return true; | |
5417e022 ZD |
1750 | } |
1751 | ||
0bbe50f6 CF |
1752 | /* Determine whether or not the trip count to ahead ratio is too small based |
1753 | on prefitablility consideration. | |
db34470d | 1754 | AHEAD: the iteration ahead distance, |
0bbe50f6 CF |
1755 | EST_NITER: the estimated trip count. */ |
1756 | ||
1757 | static bool | |
1758 | trip_count_to_ahead_ratio_too_small_p (unsigned ahead, HOST_WIDE_INT est_niter) | |
1759 | { | |
1760 | /* Assume trip count to ahead ratio is big enough if the trip count could not | |
1761 | be estimated at compile time. */ | |
1762 | if (est_niter < 0) | |
1763 | return false; | |
1764 | ||
1765 | if (est_niter < (HOST_WIDE_INT) (TRIP_COUNT_TO_AHEAD_RATIO * ahead)) | |
1766 | { | |
1767 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1768 | fprintf (dump_file, | |
1769 | "Not prefetching -- loop estimated to roll only %d times\n", | |
1770 | (int) est_niter); | |
1771 | return true; | |
1772 | } | |
1773 | ||
1774 | return false; | |
1775 | } | |
1776 | ||
1777 | /* Determine whether or not the number of memory references in the loop is | |
1778 | reasonable based on the profitablity and compilation time considerations. | |
db34470d | 1779 | NINSNS: estimated number of instructions in the loop, |
db34470d GS |
1780 | MEM_REF_COUNT: total number of memory references in the loop. */ |
1781 | ||
b8698a0f | 1782 | static bool |
0bbe50f6 | 1783 | mem_ref_count_reasonable_p (unsigned ninsns, unsigned mem_ref_count) |
db34470d | 1784 | { |
0bbe50f6 | 1785 | int insn_to_mem_ratio; |
db34470d GS |
1786 | |
1787 | if (mem_ref_count == 0) | |
1788 | return false; | |
1789 | ||
0bbe50f6 CF |
1790 | /* Miss rate computation (is_miss_rate_acceptable) and dependence analysis |
1791 | (compute_all_dependences) have high costs based on quadratic complexity. | |
1792 | To avoid huge compilation time, we give up prefetching if mem_ref_count | |
1793 | is too large. */ | |
1794 | if (mem_ref_count > PREFETCH_MAX_MEM_REFS_PER_LOOP) | |
1795 | return false; | |
1796 | ||
b8698a0f L |
1797 | /* Prefetching improves performance by overlapping cache missing |
1798 | memory accesses with CPU operations. If the loop does not have | |
1799 | enough CPU operations to overlap with memory operations, prefetching | |
1800 | won't give a significant benefit. One approximate way of checking | |
1801 | this is to require the ratio of instructions to memory references to | |
db34470d GS |
1802 | be above a certain limit. This approximation works well in practice. |
1803 | TODO: Implement a more precise computation by estimating the time | |
1804 | for each CPU or memory op in the loop. Time estimates for memory ops | |
1805 | should account for cache misses. */ | |
b8698a0f | 1806 | insn_to_mem_ratio = ninsns / mem_ref_count; |
db34470d GS |
1807 | |
1808 | if (insn_to_mem_ratio < PREFETCH_MIN_INSN_TO_MEM_RATIO) | |
55e5a2eb CF |
1809 | { |
1810 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1811 | fprintf (dump_file, | |
1812 | "Not prefetching -- instruction to memory reference ratio (%d) too small\n", | |
1813 | insn_to_mem_ratio); | |
1814 | return false; | |
1815 | } | |
db34470d | 1816 | |
0bbe50f6 CF |
1817 | return true; |
1818 | } | |
1819 | ||
1820 | /* Determine whether or not the instruction to prefetch ratio in the loop is | |
1821 | too small based on the profitablity consideration. | |
1822 | NINSNS: estimated number of instructions in the loop, | |
1823 | PREFETCH_COUNT: an estimate of the number of prefetches, | |
1824 | UNROLL_FACTOR: the factor to unroll the loop if prefetching. */ | |
1825 | ||
1826 | static bool | |
1827 | insn_to_prefetch_ratio_too_small_p (unsigned ninsns, unsigned prefetch_count, | |
1828 | unsigned unroll_factor) | |
1829 | { | |
1830 | int insn_to_prefetch_ratio; | |
1831 | ||
d3a9b459 CF |
1832 | /* Prefetching most likely causes performance degradation when the instruction |
1833 | to prefetch ratio is too small. Too many prefetch instructions in a loop | |
1834 | may reduce the I-cache performance. | |
ccacf0e1 CF |
1835 | (unroll_factor * ninsns) is used to estimate the number of instructions in |
1836 | the unrolled loop. This implementation is a bit simplistic -- the number | |
1837 | of issued prefetch instructions is also affected by unrolling. So, | |
1838 | prefetch_mod and the unroll factor should be taken into account when | |
1839 | determining prefetch_count. Also, the number of insns of the unrolled | |
1840 | loop will usually be significantly smaller than the number of insns of the | |
1841 | original loop * unroll_factor (at least the induction variable increases | |
1842 | and the exit branches will get eliminated), so it might be better to use | |
1843 | tree_estimate_loop_size + estimated_unrolled_size. */ | |
d3a9b459 CF |
1844 | insn_to_prefetch_ratio = (unroll_factor * ninsns) / prefetch_count; |
1845 | if (insn_to_prefetch_ratio < MIN_INSN_TO_PREFETCH_RATIO) | |
db34470d | 1846 | { |
d3a9b459 CF |
1847 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1848 | fprintf (dump_file, | |
1849 | "Not prefetching -- instruction to prefetch ratio (%d) too small\n", | |
1850 | insn_to_prefetch_ratio); | |
0bbe50f6 | 1851 | return true; |
db34470d | 1852 | } |
b8698a0f | 1853 | |
0bbe50f6 | 1854 | return false; |
db34470d GS |
1855 | } |
1856 | ||
1857 | ||
b076a3fd | 1858 | /* Issue prefetch instructions for array references in LOOP. Returns |
d73be268 | 1859 | true if the LOOP was unrolled. */ |
b076a3fd ZD |
1860 | |
1861 | static bool | |
d73be268 | 1862 | loop_prefetch_arrays (struct loop *loop) |
b076a3fd ZD |
1863 | { |
1864 | struct mem_ref_group *refs; | |
2711355f ZD |
1865 | unsigned ahead, ninsns, time, unroll_factor; |
1866 | HOST_WIDE_INT est_niter; | |
b076a3fd | 1867 | struct tree_niter_desc desc; |
79f5e442 | 1868 | bool unrolled = false, no_other_refs; |
db34470d GS |
1869 | unsigned prefetch_count; |
1870 | unsigned mem_ref_count; | |
b076a3fd | 1871 | |
efd8f750 | 1872 | if (optimize_loop_nest_for_size_p (loop)) |
2732d767 ZD |
1873 | { |
1874 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1875 | fprintf (dump_file, " ignored (cold area)\n"); | |
1876 | return false; | |
1877 | } | |
1878 | ||
0bbe50f6 CF |
1879 | /* FIXME: the time should be weighted by the probabilities of the blocks in |
1880 | the loop body. */ | |
1881 | time = tree_num_loop_insns (loop, &eni_time_weights); | |
1882 | if (time == 0) | |
1883 | return false; | |
1884 | ||
1885 | ahead = (PREFETCH_LATENCY + time - 1) / time; | |
652c4c71 | 1886 | est_niter = estimated_stmt_executions_int (loop); |
e5b332cd RG |
1887 | if (est_niter == -1) |
1888 | est_niter = max_stmt_executions_int (loop); | |
0bbe50f6 CF |
1889 | |
1890 | /* Prefetching is not likely to be profitable if the trip count to ahead | |
1891 | ratio is too small. */ | |
1892 | if (trip_count_to_ahead_ratio_too_small_p (ahead, est_niter)) | |
1893 | return false; | |
1894 | ||
1895 | ninsns = tree_num_loop_insns (loop, &eni_size_weights); | |
1896 | ||
b076a3fd | 1897 | /* Step 1: gather the memory references. */ |
db34470d | 1898 | refs = gather_memory_references (loop, &no_other_refs, &mem_ref_count); |
b076a3fd | 1899 | |
0bbe50f6 CF |
1900 | /* Give up prefetching if the number of memory references in the |
1901 | loop is not reasonable based on profitablity and compilation time | |
1902 | considerations. */ | |
1903 | if (!mem_ref_count_reasonable_p (ninsns, mem_ref_count)) | |
1904 | goto fail; | |
1905 | ||
b076a3fd ZD |
1906 | /* Step 2: estimate the reuse effects. */ |
1907 | prune_by_reuse (refs); | |
1908 | ||
d5058523 | 1909 | if (nothing_to_prefetch_p (refs)) |
b076a3fd ZD |
1910 | goto fail; |
1911 | ||
1e373390 RG |
1912 | if (!determine_loop_nest_reuse (loop, refs, no_other_refs)) |
1913 | goto fail; | |
5417e022 | 1914 | |
0bbe50f6 | 1915 | /* Step 3: determine unroll factor. */ |
2711355f ZD |
1916 | unroll_factor = determine_unroll_factor (loop, refs, ninsns, &desc, |
1917 | est_niter); | |
d5058523 CF |
1918 | |
1919 | /* Estimate prefetch count for the unrolled loop. */ | |
1920 | prefetch_count = estimate_prefetch_count (refs, unroll_factor); | |
1921 | if (prefetch_count == 0) | |
1922 | goto fail; | |
1923 | ||
2711355f | 1924 | if (dump_file && (dump_flags & TDF_DETAILS)) |
b8698a0f | 1925 | fprintf (dump_file, "Ahead %d, unroll factor %d, trip count " |
d81f5387 | 1926 | HOST_WIDE_INT_PRINT_DEC "\n" |
b8698a0f L |
1927 | "insn count %d, mem ref count %d, prefetch count %d\n", |
1928 | ahead, unroll_factor, est_niter, | |
1929 | ninsns, mem_ref_count, prefetch_count); | |
db34470d | 1930 | |
0bbe50f6 CF |
1931 | /* Prefetching is not likely to be profitable if the instruction to prefetch |
1932 | ratio is too small. */ | |
1933 | if (insn_to_prefetch_ratio_too_small_p (ninsns, prefetch_count, | |
1934 | unroll_factor)) | |
db34470d GS |
1935 | goto fail; |
1936 | ||
1937 | mark_nontemporal_stores (loop, refs); | |
2711355f | 1938 | |
b076a3fd ZD |
1939 | /* Step 4: what to prefetch? */ |
1940 | if (!schedule_prefetches (refs, unroll_factor, ahead)) | |
1941 | goto fail; | |
1942 | ||
1943 | /* Step 5: unroll the loop. TODO -- peeling of first and last few | |
1944 | iterations so that we do not issue superfluous prefetches. */ | |
1945 | if (unroll_factor != 1) | |
1946 | { | |
d73be268 | 1947 | tree_unroll_loop (loop, unroll_factor, |
b076a3fd ZD |
1948 | single_dom_exit (loop), &desc); |
1949 | unrolled = true; | |
1950 | } | |
1951 | ||
1952 | /* Step 6: issue the prefetches. */ | |
1953 | issue_prefetches (refs, unroll_factor, ahead); | |
1954 | ||
1955 | fail: | |
1956 | release_mem_refs (refs); | |
1957 | return unrolled; | |
1958 | } | |
1959 | ||
d73be268 | 1960 | /* Issue prefetch instructions for array references in loops. */ |
b076a3fd | 1961 | |
c7f965b6 | 1962 | unsigned int |
d73be268 | 1963 | tree_ssa_prefetch_arrays (void) |
b076a3fd | 1964 | { |
b076a3fd ZD |
1965 | struct loop *loop; |
1966 | bool unrolled = false; | |
c7f965b6 | 1967 | int todo_flags = 0; |
b076a3fd ZD |
1968 | |
1969 | if (!HAVE_prefetch | |
1970 | /* It is possible to ask compiler for say -mtune=i486 -march=pentium4. | |
1971 | -mtune=i486 causes us having PREFETCH_BLOCK 0, since this is part | |
1972 | of processor costs and i486 does not have prefetch, but | |
1973 | -march=pentium4 causes HAVE_prefetch to be true. Ugh. */ | |
1974 | || PREFETCH_BLOCK == 0) | |
c7f965b6 | 1975 | return 0; |
b076a3fd | 1976 | |
47eb5b32 ZD |
1977 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1978 | { | |
1979 | fprintf (dump_file, "Prefetching parameters:\n"); | |
1980 | fprintf (dump_file, " simultaneous prefetches: %d\n", | |
1981 | SIMULTANEOUS_PREFETCHES); | |
1982 | fprintf (dump_file, " prefetch latency: %d\n", PREFETCH_LATENCY); | |
47eb5b32 | 1983 | fprintf (dump_file, " prefetch block size: %d\n", PREFETCH_BLOCK); |
46cb0441 ZD |
1984 | fprintf (dump_file, " L1 cache size: %d lines, %d kB\n", |
1985 | L1_CACHE_SIZE_BYTES / L1_CACHE_LINE_SIZE, L1_CACHE_SIZE); | |
5417e022 | 1986 | fprintf (dump_file, " L1 cache line size: %d\n", L1_CACHE_LINE_SIZE); |
b8698a0f L |
1987 | fprintf (dump_file, " L2 cache size: %d kB\n", L2_CACHE_SIZE); |
1988 | fprintf (dump_file, " min insn-to-prefetch ratio: %d \n", | |
db34470d | 1989 | MIN_INSN_TO_PREFETCH_RATIO); |
b8698a0f | 1990 | fprintf (dump_file, " min insn-to-mem ratio: %d \n", |
db34470d | 1991 | PREFETCH_MIN_INSN_TO_MEM_RATIO); |
47eb5b32 ZD |
1992 | fprintf (dump_file, "\n"); |
1993 | } | |
1994 | ||
b076a3fd ZD |
1995 | initialize_original_copy_tables (); |
1996 | ||
e79983f4 | 1997 | if (!builtin_decl_explicit_p (BUILT_IN_PREFETCH)) |
b076a3fd | 1998 | { |
6a4825bd NF |
1999 | tree type = build_function_type_list (void_type_node, |
2000 | const_ptr_type_node, NULL_TREE); | |
c79efc4d RÁE |
2001 | tree decl = add_builtin_function ("__builtin_prefetch", type, |
2002 | BUILT_IN_PREFETCH, BUILT_IN_NORMAL, | |
2003 | NULL, NULL_TREE); | |
b076a3fd | 2004 | DECL_IS_NOVOPS (decl) = true; |
e79983f4 | 2005 | set_builtin_decl (BUILT_IN_PREFETCH, decl, false); |
b076a3fd ZD |
2006 | } |
2007 | ||
2008 | /* We assume that size of cache line is a power of two, so verify this | |
2009 | here. */ | |
2010 | gcc_assert ((PREFETCH_BLOCK & (PREFETCH_BLOCK - 1)) == 0); | |
2011 | ||
f0bd40b1 | 2012 | FOR_EACH_LOOP (loop, LI_FROM_INNERMOST) |
b076a3fd | 2013 | { |
b076a3fd ZD |
2014 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2015 | fprintf (dump_file, "Processing loop %d:\n", loop->num); | |
2016 | ||
d73be268 | 2017 | unrolled |= loop_prefetch_arrays (loop); |
b076a3fd ZD |
2018 | |
2019 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2020 | fprintf (dump_file, "\n\n"); | |
2021 | } | |
2022 | ||
2023 | if (unrolled) | |
2024 | { | |
2025 | scev_reset (); | |
c7f965b6 | 2026 | todo_flags |= TODO_cleanup_cfg; |
b076a3fd ZD |
2027 | } |
2028 | ||
2029 | free_original_copy_tables (); | |
c7f965b6 | 2030 | return todo_flags; |
b076a3fd | 2031 | } |
71343877 AM |
2032 | |
2033 | /* Prefetching. */ | |
2034 | ||
71343877 AM |
2035 | namespace { |
2036 | ||
2037 | const pass_data pass_data_loop_prefetch = | |
2038 | { | |
2039 | GIMPLE_PASS, /* type */ | |
2040 | "aprefetch", /* name */ | |
2041 | OPTGROUP_LOOP, /* optinfo_flags */ | |
71343877 AM |
2042 | TV_TREE_PREFETCH, /* tv_id */ |
2043 | ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
2044 | 0, /* properties_provided */ | |
2045 | 0, /* properties_destroyed */ | |
2046 | 0, /* todo_flags_start */ | |
2047 | 0, /* todo_flags_finish */ | |
2048 | }; | |
2049 | ||
2050 | class pass_loop_prefetch : public gimple_opt_pass | |
2051 | { | |
2052 | public: | |
2053 | pass_loop_prefetch (gcc::context *ctxt) | |
2054 | : gimple_opt_pass (pass_data_loop_prefetch, ctxt) | |
2055 | {} | |
2056 | ||
2057 | /* opt_pass methods: */ | |
1a3d085c | 2058 | virtual bool gate (function *) { return flag_prefetch_loop_arrays > 0; } |
be55bfe6 | 2059 | virtual unsigned int execute (function *); |
71343877 AM |
2060 | |
2061 | }; // class pass_loop_prefetch | |
2062 | ||
be55bfe6 TS |
2063 | unsigned int |
2064 | pass_loop_prefetch::execute (function *fun) | |
2065 | { | |
2066 | if (number_of_loops (fun) <= 1) | |
2067 | return 0; | |
2068 | ||
2069 | return tree_ssa_prefetch_arrays (); | |
2070 | } | |
2071 | ||
71343877 AM |
2072 | } // anon namespace |
2073 | ||
2074 | gimple_opt_pass * | |
2075 | make_pass_loop_prefetch (gcc::context *ctxt) | |
2076 | { | |
2077 | return new pass_loop_prefetch (ctxt); | |
2078 | } | |
2079 | ||
2080 |