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3d436d2a | 1 | /* Natural loop functions |
613c5cd0 | 2 | Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 |
3d436d2a ZD |
3 | Free Software Foundation, Inc. |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 2, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING. If not, write to the Free | |
366ccddb KC |
19 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
20 | 02110-1301, USA. */ | |
3d436d2a | 21 | |
59587b18 JQ |
22 | #ifndef GCC_CFGLOOP_H |
23 | #define GCC_CFGLOOP_H | |
24 | ||
25 | #include "basic-block.h" | |
26 | /* For rtx_code. */ | |
27 | #include "rtl.h" | |
28 | ||
3d436d2a ZD |
29 | /* Structure to hold decision about unrolling/peeling. */ |
30 | enum lpt_dec | |
31 | { | |
32 | LPT_NONE, | |
33 | LPT_PEEL_COMPLETELY, | |
34 | LPT_PEEL_SIMPLE, | |
35 | LPT_UNROLL_CONSTANT, | |
36 | LPT_UNROLL_RUNTIME, | |
37 | LPT_UNROLL_STUPID | |
38 | }; | |
39 | ||
40 | struct lpt_decision | |
41 | { | |
42 | enum lpt_dec decision; | |
43 | unsigned times; | |
44 | }; | |
45 | ||
86df10e3 SP |
46 | /* The structure describing a bound on number of iterations of a loop. */ |
47 | ||
48 | struct nb_iter_bound | |
49 | { | |
50 | tree bound; /* The expression whose value is an upper bound on the | |
51 | number of executions of anything after ... */ | |
52 | tree at_stmt; /* ... this statement during one execution of loop. */ | |
53 | tree additional; /* A conjunction of conditions the operands of BOUND | |
54 | satisfy. The additional information about the value | |
55 | of the bound may be derived from it. */ | |
56 | struct nb_iter_bound *next; | |
57 | /* The next bound in a list. */ | |
58 | }; | |
59 | ||
3d436d2a ZD |
60 | /* Structure to hold information for each natural loop. */ |
61 | struct loop | |
62 | { | |
63 | /* Index into loops array. */ | |
64 | int num; | |
65 | ||
66 | /* Basic block of loop header. */ | |
67 | basic_block header; | |
68 | ||
69 | /* Basic block of loop latch. */ | |
70 | basic_block latch; | |
71 | ||
3d436d2a ZD |
72 | /* For loop unrolling/peeling decision. */ |
73 | struct lpt_decision lpt_decision; | |
74 | ||
3d436d2a ZD |
75 | /* Number of loop insns. */ |
76 | unsigned ninsns; | |
77 | ||
78 | /* Average number of executed insns per iteration. */ | |
79 | unsigned av_ninsns; | |
80 | ||
3d436d2a ZD |
81 | /* The first block in the loop. This is not necessarily the same as |
82 | the loop header. */ | |
83 | basic_block first; | |
84 | ||
85 | /* The last block in the loop. This is not necessarily the same as | |
86 | the loop latch. */ | |
87 | basic_block last; | |
88 | ||
3d436d2a ZD |
89 | /* Number of blocks contained within the loop. */ |
90 | unsigned num_nodes; | |
91 | ||
3d436d2a ZD |
92 | /* The loop nesting depth. */ |
93 | int depth; | |
94 | ||
95 | /* Superloops of the loop. */ | |
96 | struct loop **pred; | |
97 | ||
98 | /* The height of the loop (enclosed loop levels) within the loop | |
99 | hierarchy tree. */ | |
100 | int level; | |
101 | ||
102 | /* The outer (parent) loop or NULL if outermost loop. */ | |
103 | struct loop *outer; | |
104 | ||
105 | /* The first inner (child) loop or NULL if innermost loop. */ | |
106 | struct loop *inner; | |
107 | ||
108 | /* Link to the next (sibling) loop. */ | |
109 | struct loop *next; | |
110 | ||
111 | /* Loop that is copy of this loop. */ | |
112 | struct loop *copy; | |
113 | ||
6356f892 | 114 | /* Nonzero if the loop is invalid (e.g., contains setjmp.). */ |
3d436d2a ZD |
115 | int invalid; |
116 | ||
117 | /* Auxiliary info specific to a pass. */ | |
118 | void *aux; | |
119 | ||
120 | /* The following are currently used by loop.c but they are likely to | |
75473b02 | 121 | disappear when loop.c is replaced and removed. */ |
3d436d2a | 122 | |
3d436d2a ZD |
123 | /* The NOTE_INSN_LOOP_BEG. */ |
124 | rtx start; | |
125 | ||
126 | /* The NOTE_INSN_LOOP_END. */ | |
127 | rtx end; | |
128 | ||
129 | /* For a rotated loop that is entered near the bottom, | |
130 | this is the label at the top. Otherwise it is zero. */ | |
131 | rtx top; | |
132 | ||
133 | /* Place in the loop where control enters. */ | |
134 | rtx scan_start; | |
135 | ||
136 | /* The position where to sink insns out of the loop. */ | |
137 | rtx sink; | |
138 | ||
139 | /* List of all LABEL_REFs which refer to code labels outside the | |
140 | loop. Used by routines that need to know all loop exits, such as | |
141 | final_biv_value and final_giv_value. | |
142 | ||
143 | This does not include loop exits due to return instructions. | |
144 | This is because all bivs and givs are pseudos, and hence must be | |
145 | dead after a return, so the presence of a return does not affect | |
146 | any of the optimizations that use this info. It is simpler to | |
147 | just not include return instructions on this list. */ | |
148 | rtx exit_labels; | |
149 | ||
150 | /* The number of LABEL_REFs on exit_labels for this loop and all | |
151 | loops nested inside it. */ | |
152 | int exit_count; | |
e9eb809d | 153 | |
9baba81b SP |
154 | /* The probable number of times the loop is executed at runtime. |
155 | This is an INTEGER_CST or an expression containing symbolic | |
156 | names. Don't access this field directly: | |
157 | number_of_iterations_in_loop computes and caches the computed | |
158 | information in this field. */ | |
159 | tree nb_iterations; | |
160 | ||
86df10e3 SP |
161 | /* An INTEGER_CST estimation of the number of iterations. NULL_TREE |
162 | if there is no estimation. */ | |
163 | tree estimated_nb_iterations; | |
164 | ||
e9eb809d ZD |
165 | /* Upper bound on number of iterations of a loop. */ |
166 | struct nb_iter_bound *bounds; | |
82b85a85 ZD |
167 | |
168 | /* If not NULL, loop has just single exit edge stored here (edges to the | |
169 | EXIT_BLOCK_PTR do not count. */ | |
170 | edge single_exit; | |
86df10e3 SP |
171 | |
172 | /* True when the loop does not carry data dependences, and | |
173 | consequently the iterations can be executed in any order. False | |
174 | when the loop carries data dependences, or when the property is | |
175 | not decidable. */ | |
176 | bool parallel_p; | |
3d436d2a ZD |
177 | }; |
178 | ||
179 | /* Flags for state of loop structure. */ | |
180 | enum | |
181 | { | |
182 | LOOPS_HAVE_PREHEADERS = 1, | |
183 | LOOPS_HAVE_SIMPLE_LATCHES = 2, | |
82b85a85 ZD |
184 | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4, |
185 | LOOPS_HAVE_MARKED_SINGLE_EXITS = 8 | |
3d436d2a ZD |
186 | }; |
187 | ||
188 | /* Structure to hold CFG information about natural loops within a function. */ | |
189 | struct loops | |
190 | { | |
191 | /* Number of natural loops in the function. */ | |
192 | unsigned num; | |
193 | ||
3d436d2a ZD |
194 | /* Array of natural loop descriptors (scanning this array in reverse order |
195 | will find the inner loops before their enclosing outer loops). */ | |
196 | struct loop *array; | |
197 | ||
198 | /* The above array is unused in new loop infrastructure and is kept only for | |
199 | purposes of the old loop optimizer. Instead we store just pointers to | |
43a613f7 DB |
200 | loops here. |
201 | Note that a loop in this array may actually be NULL, if the loop | |
202 | has been removed and the entire loops structure has not been | |
203 | recomputed since that time. */ | |
3d436d2a ZD |
204 | struct loop **parray; |
205 | ||
206 | /* Pointer to root of loop hierarchy tree. */ | |
207 | struct loop *tree_root; | |
208 | ||
209 | /* Information derived from the CFG. */ | |
210 | struct cfg | |
211 | { | |
3d436d2a ZD |
212 | /* The ordering of the basic blocks in a depth first search. */ |
213 | int *dfs_order; | |
214 | ||
215 | /* The reverse completion ordering of the basic blocks found in a | |
216 | depth first search. */ | |
217 | int *rc_order; | |
218 | } cfg; | |
219 | ||
220 | /* Headers shared by multiple loops that should be merged. */ | |
221 | sbitmap shared_headers; | |
222 | ||
223 | /* State of loops. */ | |
224 | int state; | |
225 | }; | |
226 | ||
9baba81b SP |
227 | /* The loop tree currently optimized. */ |
228 | ||
229 | extern struct loops *current_loops; | |
230 | ||
3d436d2a | 231 | /* Loop recognition. */ |
70388d94 | 232 | extern int flow_loops_find (struct loops *); |
d329e058 AJ |
233 | extern void flow_loops_free (struct loops *); |
234 | extern void flow_loops_dump (const struct loops *, FILE *, | |
235 | void (*)(const struct loop *, FILE *, int), int); | |
236 | extern void flow_loop_dump (const struct loop *, FILE *, | |
237 | void (*)(const struct loop *, FILE *, int), int); | |
d329e058 | 238 | extern void flow_loop_free (struct loop *); |
2b271002 ZD |
239 | int flow_loop_nodes_find (basic_block, struct loop *); |
240 | void fix_loop_structure (struct loops *, bitmap changed_bbs); | |
d329e058 | 241 | void mark_irreducible_loops (struct loops *); |
82b85a85 | 242 | void mark_single_exit_loops (struct loops *); |
6de9cd9a | 243 | extern void create_loop_notes (void); |
3d436d2a | 244 | |
4d6922ee | 245 | /* Loop data structure manipulation/querying. */ |
d329e058 AJ |
246 | extern void flow_loop_tree_node_add (struct loop *, struct loop *); |
247 | extern void flow_loop_tree_node_remove (struct loop *); | |
248 | extern bool flow_loop_outside_edge_p (const struct loop *, edge); | |
249 | extern bool flow_loop_nested_p (const struct loop *, const struct loop *); | |
250 | extern bool flow_bb_inside_loop_p (const struct loop *, const basic_block); | |
251 | extern struct loop * find_common_loop (struct loop *, struct loop *); | |
a7e5372d | 252 | struct loop *superloop_at_depth (struct loop *, unsigned); |
82b85a85 | 253 | extern unsigned tree_num_loop_insns (struct loop *); |
d329e058 AJ |
254 | extern int num_loop_insns (struct loop *); |
255 | extern int average_num_loop_insns (struct loop *); | |
689ba89d | 256 | extern unsigned get_loop_level (const struct loop *); |
70388d94 ZD |
257 | extern bool loop_exit_edge_p (const struct loop *, edge); |
258 | extern void mark_loop_exit_edges (struct loops *); | |
3d436d2a ZD |
259 | |
260 | /* Loops & cfg manipulation. */ | |
d329e058 | 261 | extern basic_block *get_loop_body (const struct loop *); |
50654f6c | 262 | extern basic_block *get_loop_body_in_dom_order (const struct loop *); |
40923b20 | 263 | extern basic_block *get_loop_body_in_bfs_order (const struct loop *); |
d329e058 | 264 | extern edge *get_loop_exit_edges (const struct loop *, unsigned *); |
50654f6c | 265 | extern unsigned num_loop_branches (const struct loop *); |
3d436d2a | 266 | |
d329e058 AJ |
267 | extern edge loop_preheader_edge (const struct loop *); |
268 | extern edge loop_latch_edge (const struct loop *); | |
3d436d2a | 269 | |
d329e058 AJ |
270 | extern void add_bb_to_loop (basic_block, struct loop *); |
271 | extern void remove_bb_from_loops (basic_block); | |
3d436d2a | 272 | |
d329e058 AJ |
273 | extern void cancel_loop (struct loops *, struct loop *); |
274 | extern void cancel_loop_tree (struct loops *, struct loop *); | |
3d436d2a | 275 | |
d47cc544 | 276 | extern basic_block loop_split_edge_with (edge, rtx); |
d329e058 | 277 | extern int fix_loop_placement (struct loop *); |
3d436d2a ZD |
278 | |
279 | enum | |
280 | { | |
bc35512f | 281 | CP_SIMPLE_PREHEADERS = 1 |
3d436d2a ZD |
282 | }; |
283 | ||
d329e058 AJ |
284 | extern void create_preheaders (struct loops *, int); |
285 | extern void force_single_succ_latches (struct loops *); | |
3d436d2a | 286 | |
d329e058 | 287 | extern void verify_loop_structure (struct loops *); |
3d436d2a ZD |
288 | |
289 | /* Loop analysis. */ | |
6c878b23 | 290 | extern bool just_once_each_iteration_p (const struct loop *, basic_block); |
d329e058 | 291 | extern unsigned expected_loop_iterations (const struct loop *); |
75c70254 | 292 | extern rtx doloop_condition_get (rtx); |
617b465c ZD |
293 | |
294 | /* Loop manipulation. */ | |
d329e058 | 295 | extern bool can_duplicate_loop_p (struct loop *loop); |
617b465c ZD |
296 | |
297 | #define DLTHE_FLAG_UPDATE_FREQ 1 /* Update frequencies in | |
298 | duplicate_loop_to_header_edge. */ | |
7f7b1718 JH |
299 | #define DLTHE_RECORD_COPY_NUMBER 2 /* Record copy number in the aux |
300 | field of newly create BB. */ | |
178df94f JH |
301 | #define DLTHE_FLAG_COMPLETTE_PEEL 4 /* Update frequencies expecting |
302 | a complette peeling. */ | |
617b465c | 303 | |
f67d92e9 DB |
304 | extern struct loop * duplicate_loop (struct loops *, struct loop *, |
305 | struct loop *); | |
1cb7dfc3 MH |
306 | extern bool duplicate_loop_to_header_edge (struct loop *, edge, struct loops *, |
307 | unsigned, sbitmap, edge, edge *, | |
308 | unsigned *, int); | |
5132abc2 KH |
309 | extern struct loop *loopify (struct loops *, edge, edge, |
310 | basic_block, edge, edge, bool); | |
1cb7dfc3 MH |
311 | struct loop * loop_version (struct loops *, struct loop *, void *, |
312 | basic_block *); | |
d329e058 | 313 | extern bool remove_path (struct loops *, edge); |
92fc4a2f | 314 | extern edge split_loop_bb (basic_block, void *); |
617b465c | 315 | |
50654f6c ZD |
316 | /* Induction variable analysis. */ |
317 | ||
318 | /* The description of induction variable. The things are a bit complicated | |
319 | due to need to handle subregs and extends. The value of the object described | |
320 | by it can be obtained as follows (all computations are done in extend_mode): | |
321 | ||
322 | Value in i-th iteration is | |
323 | delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)). | |
324 | ||
325 | If first_special is true, the value in the first iteration is | |
326 | delta + mult * base | |
327 | ||
f822d252 | 328 | If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is |
50654f6c ZD |
329 | subreg_{mode} (base + i * step) |
330 | ||
331 | The get_iv_value function can be used to obtain these expressions. | |
332 | ||
333 | ??? Add a third mode field that would specify the mode in that inner | |
334 | computation is done, which would enable it to be different from the | |
335 | outer one? */ | |
336 | ||
337 | struct rtx_iv | |
338 | { | |
339 | /* Its base and step (mode of base and step is supposed to be extend_mode, | |
340 | see the description above). */ | |
341 | rtx base, step; | |
342 | ||
f822d252 | 343 | /* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or UNKNOWN). */ |
50654f6c ZD |
344 | enum rtx_code extend; |
345 | ||
346 | /* Operations applied in the extended mode. */ | |
347 | rtx delta, mult; | |
348 | ||
349 | /* The mode it is extended to. */ | |
350 | enum machine_mode extend_mode; | |
351 | ||
352 | /* The mode the variable iterates in. */ | |
353 | enum machine_mode mode; | |
354 | ||
355 | /* Whether we have already filled the remaining fields. */ | |
356 | unsigned analysed : 1; | |
357 | ||
358 | /* Whether the first iteration needs to be handled specially. */ | |
359 | unsigned first_special : 1; | |
360 | }; | |
361 | ||
f2dca510 ZD |
362 | /* The description of an exit from the loop and of the number of iterations |
363 | till we take the exit. */ | |
50654f6c ZD |
364 | |
365 | struct niter_desc | |
366 | { | |
367 | /* The edge out of the loop. */ | |
368 | edge out_edge; | |
369 | ||
370 | /* The other edge leading from the condition. */ | |
371 | edge in_edge; | |
372 | ||
373 | /* True if we are able to say anything about number of iterations of the | |
374 | loop. */ | |
375 | bool simple_p; | |
376 | ||
377 | /* True if the loop iterates the constant number of times. */ | |
378 | bool const_iter; | |
379 | ||
380 | /* Number of iterations if constant. */ | |
381 | unsigned HOST_WIDEST_INT niter; | |
382 | ||
383 | /* Upper bound on the number of iterations. */ | |
384 | unsigned HOST_WIDEST_INT niter_max; | |
385 | ||
386 | /* Assumptions under that the rest of the information is valid. */ | |
387 | rtx assumptions; | |
388 | ||
389 | /* Assumptions under that the loop ends before reaching the latch, | |
390 | even if value of niter_expr says otherwise. */ | |
391 | rtx noloop_assumptions; | |
392 | ||
393 | /* Condition under that the loop is infinite. */ | |
394 | rtx infinite; | |
395 | ||
396 | /* Whether the comparison is signed. */ | |
397 | bool signed_p; | |
398 | ||
399 | /* The mode in that niter_expr should be computed. */ | |
400 | enum machine_mode mode; | |
401 | ||
402 | /* The number of iterations of the loop. */ | |
403 | rtx niter_expr; | |
404 | }; | |
405 | ||
406 | extern void iv_analysis_loop_init (struct loop *); | |
407 | extern rtx iv_get_reaching_def (rtx, rtx); | |
6d4e0ecc | 408 | extern bool iv_analyze (rtx, rtx, struct rtx_iv *); |
50654f6c | 409 | extern rtx get_iv_value (struct rtx_iv *, rtx); |
113d659a | 410 | extern bool biv_p (rtx, rtx); |
50654f6c | 411 | extern void find_simple_exit (struct loop *, struct niter_desc *); |
50654f6c ZD |
412 | extern void iv_analysis_done (void); |
413 | ||
414 | extern struct niter_desc *get_simple_loop_desc (struct loop *loop); | |
415 | extern void free_simple_loop_desc (struct loop *loop); | |
416 | ||
417 | static inline struct niter_desc * | |
418 | simple_loop_desc (struct loop *loop) | |
419 | { | |
420 | return loop->aux; | |
421 | } | |
422 | ||
8b11a64c ZD |
423 | /* The properties of the target. */ |
424 | ||
425 | extern unsigned target_avail_regs; /* Number of available registers. */ | |
426 | extern unsigned target_res_regs; /* Number of reserved registers. */ | |
427 | extern unsigned target_small_cost; /* The cost for register when there | |
428 | is a free one. */ | |
429 | extern unsigned target_pres_cost; /* The cost for register when there are | |
430 | not too many free ones. */ | |
431 | extern unsigned target_spill_cost; /* The cost for register when we need | |
432 | to spill. */ | |
433 | ||
5e962776 ZD |
434 | /* Register pressure estimation for induction variable optimizations & loop |
435 | invariant motion. */ | |
436 | extern unsigned global_cost_for_size (unsigned, unsigned, unsigned); | |
437 | extern void init_set_costs (void); | |
438 | ||
617b465c | 439 | /* Loop optimizer initialization. */ |
d329e058 AJ |
440 | extern struct loops *loop_optimizer_init (FILE *); |
441 | extern void loop_optimizer_finalize (struct loops *, FILE *); | |
617b465c ZD |
442 | |
443 | /* Optimization passes. */ | |
d329e058 | 444 | extern void unswitch_loops (struct loops *); |
617b465c | 445 | |
b17d5d7c ZD |
446 | enum |
447 | { | |
448 | UAP_PEEL = 1, /* Enables loop peeling. */ | |
449 | UAP_UNROLL = 2, /* Enables peeling of loops if it seems profitable. */ | |
450 | UAP_UNROLL_ALL = 4 /* Enables peeling of all loops. */ | |
451 | }; | |
452 | ||
d329e058 | 453 | extern void unroll_and_peel_loops (struct loops *, int); |
689ba89d | 454 | extern void doloop_optimize_loops (struct loops *); |
5e962776 | 455 | extern void move_loop_invariants (struct loops *); |
86df10e3 | 456 | extern void record_estimate (struct loop *, tree, tree, tree); |
59587b18 | 457 | |
c94583fe ZD |
458 | /* Old loop optimizer interface. */ |
459 | ||
460 | /* Flags passed to loop_optimize. */ | |
461 | #define LOOP_PREFETCH 1 | |
462 | ||
463 | extern void loop_optimize (rtx, FILE *, int); | |
464 | ||
59587b18 | 465 | #endif /* GCC_CFGLOOP_H */ |