Commit | Line | Data |
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c906ae81 C |
1 | /* Move constant computations out of loops. |
2 | Copyright (C) 1987, 1988, 1989, 1991, 1992 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GNU CC. | |
5 | ||
6 | GNU CC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU CC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU CC; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | ||
21 | /* This is the loop optimization pass of the compiler. | |
22 | It finds invariant computations within loops and moves them | |
23 | to the beginning of the loop. Then it identifies basic and | |
24 | general induction variables. Strength reduction is applied to the general | |
25 | induction variables, and induction variable elimination is applied to | |
26 | the basic induction variables. | |
27 | ||
28 | It also finds cases where | |
29 | a register is set within the loop by zero-extending a narrower value | |
30 | and changes these to zero the entire register once before the loop | |
31 | and merely copy the low part within the loop. | |
32 | ||
33 | Most of the complexity is in heuristics to decide when it is worth | |
34 | while to do these things. */ | |
35 | ||
36 | #include <stdio.h> | |
37 | #include "config.h" | |
38 | #include "rtl.h" | |
39 | #include "obstack.h" | |
40 | #include "expr.h" | |
41 | #include "insn-config.h" | |
42 | #include "insn-flags.h" | |
43 | #include "regs.h" | |
44 | #include "hard-reg-set.h" | |
45 | #include "recog.h" | |
46 | #include "flags.h" | |
47 | #include "real.h" | |
48 | #include "loop.h" | |
49 | ||
50 | /* Vector mapping INSN_UIDs to luids. | |
51 | The luids are like uids but increase monotonically always. | |
52 | We use them to see whether a jump comes from outside a given loop. */ | |
53 | ||
54 | int *uid_luid; | |
55 | ||
56 | /* Indexed by INSN_UID, contains the ordinal giving the (innermost) loop | |
57 | number the insn is contained in. */ | |
58 | ||
59 | int *uid_loop_num; | |
60 | ||
61 | /* 1 + largest uid of any insn. */ | |
62 | ||
63 | int max_uid_for_loop; | |
64 | ||
65 | /* 1 + luid of last insn. */ | |
66 | ||
67 | static int max_luid; | |
68 | ||
69 | /* Number of loops detected in current function. Used as index to the | |
70 | next few tables. */ | |
71 | ||
72 | static int max_loop_num; | |
73 | ||
74 | /* Indexed by loop number, contains the first and last insn of each loop. */ | |
75 | ||
76 | static rtx *loop_number_loop_starts, *loop_number_loop_ends; | |
77 | ||
78 | /* For each loop, gives the containing loop number, -1 if none. */ | |
79 | ||
80 | int *loop_outer_loop; | |
81 | ||
82 | /* Indexed by loop number, contains a nonzero value if the "loop" isn't | |
83 | really a loop (an insn outside the loop branches into it). */ | |
84 | ||
85 | static char *loop_invalid; | |
86 | ||
87 | /* Indexed by loop number, links together all LABEL_REFs which refer to | |
88 | code labels outside the loop. Used by routines that need to know all | |
89 | loop exits, such as final_biv_value and final_giv_value. | |
90 | ||
91 | This does not include loop exits due to return instructions. This is | |
92 | because all bivs and givs are pseudos, and hence must be dead after a | |
93 | return, so the presense of a return does not affect any of the | |
94 | optimizations that use this info. It is simpler to just not include return | |
95 | instructions on this list. */ | |
96 | ||
97 | rtx *loop_number_exit_labels; | |
98 | ||
99 | /* Holds the number of loop iterations. It is zero if the number could not be | |
100 | calculated. Must be unsigned since the number of iterations can | |
101 | be as high as 2^wordsize-1. For loops with a wider iterator, this number | |
102 | will will be zero if the number of loop iterations is too large for an | |
103 | unsigned integer to hold. */ | |
104 | ||
105 | unsigned HOST_WIDE_INT loop_n_iterations; | |
106 | ||
107 | /* Nonzero if there is a subroutine call in the current loop. | |
108 | (unknown_address_altered is also nonzero in this case.) */ | |
109 | ||
110 | static int loop_has_call; | |
111 | ||
112 | /* Nonzero if there is a volatile memory reference in the current | |
113 | loop. */ | |
114 | ||
115 | static int loop_has_volatile; | |
116 | ||
117 | /* Added loop_continue which is the NOTE_INSN_LOOP_CONT of the | |
118 | current loop. A continue statement will generate a branch to | |
119 | NEXT_INSN (loop_continue). */ | |
120 | ||
121 | static rtx loop_continue; | |
122 | ||
123 | /* Indexed by register number, contains the number of times the reg | |
124 | is set during the loop being scanned. | |
125 | During code motion, a negative value indicates a reg that has been | |
126 | made a candidate; in particular -2 means that it is an candidate that | |
127 | we know is equal to a constant and -1 means that it is an candidate | |
128 | not known equal to a constant. | |
129 | After code motion, regs moved have 0 (which is accurate now) | |
130 | while the failed candidates have the original number of times set. | |
131 | ||
132 | Therefore, at all times, == 0 indicates an invariant register; | |
133 | < 0 a conditionally invariant one. */ | |
134 | ||
135 | static short *n_times_set; | |
136 | ||
137 | /* Original value of n_times_set; same except that this value | |
138 | is not set negative for a reg whose sets have been made candidates | |
139 | and not set to 0 for a reg that is moved. */ | |
140 | ||
141 | static short *n_times_used; | |
142 | ||
143 | /* Index by register number, 1 indicates that the register | |
144 | cannot be moved or strength reduced. */ | |
145 | ||
146 | static char *may_not_optimize; | |
147 | ||
148 | /* Nonzero means reg N has already been moved out of one loop. | |
149 | This reduces the desire to move it out of another. */ | |
150 | ||
151 | static char *moved_once; | |
152 | ||
153 | /* Array of MEMs that are stored in this loop. If there are too many to fit | |
154 | here, we just turn on unknown_address_altered. */ | |
155 | ||
156 | #define NUM_STORES 20 | |
157 | static rtx loop_store_mems[NUM_STORES]; | |
158 | ||
159 | /* Index of first available slot in above array. */ | |
160 | static int loop_store_mems_idx; | |
161 | ||
162 | /* Nonzero if we don't know what MEMs were changed in the current loop. | |
163 | This happens if the loop contains a call (in which case `loop_has_call' | |
164 | will also be set) or if we store into more than NUM_STORES MEMs. */ | |
165 | ||
166 | static int unknown_address_altered; | |
167 | ||
168 | /* Count of movable (i.e. invariant) instructions discovered in the loop. */ | |
169 | static int num_movables; | |
170 | ||
171 | /* Count of memory write instructions discovered in the loop. */ | |
172 | static int num_mem_sets; | |
173 | ||
174 | /* Number of loops contained within the current one, including itself. */ | |
175 | static int loops_enclosed; | |
176 | ||
177 | /* Bound on pseudo register number before loop optimization. | |
178 | A pseudo has valid regscan info if its number is < max_reg_before_loop. */ | |
179 | int max_reg_before_loop; | |
180 | ||
181 | /* This obstack is used in product_cheap_p to allocate its rtl. It | |
182 | may call gen_reg_rtx which, in turn, may reallocate regno_reg_rtx. | |
183 | If we used the same obstack that it did, we would be deallocating | |
184 | that array. */ | |
185 | ||
186 | static struct obstack temp_obstack; | |
187 | ||
188 | /* This is where the pointer to the obstack being used for RTL is stored. */ | |
189 | ||
190 | extern struct obstack *rtl_obstack; | |
191 | ||
192 | #define obstack_chunk_alloc xmalloc | |
193 | #define obstack_chunk_free free | |
194 | ||
195 | extern char *oballoc (); | |
196 | \f | |
197 | /* During the analysis of a loop, a chain of `struct movable's | |
198 | is made to record all the movable insns found. | |
199 | Then the entire chain can be scanned to decide which to move. */ | |
200 | ||
201 | struct movable | |
202 | { | |
203 | rtx insn; /* A movable insn */ | |
204 | rtx set_src; /* The expression this reg is set from. */ | |
205 | rtx set_dest; /* The destination of this SET. */ | |
206 | rtx dependencies; /* When INSN is libcall, this is an EXPR_LIST | |
207 | of any registers used within the LIBCALL. */ | |
208 | int consec; /* Number of consecutive following insns | |
209 | that must be moved with this one. */ | |
210 | int regno; /* The register it sets */ | |
211 | short lifetime; /* lifetime of that register; | |
212 | may be adjusted when matching movables | |
213 | that load the same value are found. */ | |
214 | short savings; /* Number of insns we can move for this reg, | |
215 | including other movables that force this | |
216 | or match this one. */ | |
217 | unsigned int cond : 1; /* 1 if only conditionally movable */ | |
218 | unsigned int force : 1; /* 1 means MUST move this insn */ | |
219 | unsigned int global : 1; /* 1 means reg is live outside this loop */ | |
220 | /* If PARTIAL is 1, GLOBAL means something different: | |
221 | that the reg is live outside the range from where it is set | |
222 | to the following label. */ | |
223 | unsigned int done : 1; /* 1 inhibits further processing of this */ | |
224 | ||
225 | unsigned int partial : 1; /* 1 means this reg is used for zero-extending. | |
226 | In particular, moving it does not make it | |
227 | invariant. */ | |
228 | unsigned int move_insn : 1; /* 1 means that we call emit_move_insn to | |
229 | load SRC, rather than copying INSN. */ | |
230 | unsigned int is_equiv : 1; /* 1 means a REG_EQUIV is present on INSN. */ | |
231 | enum machine_mode savemode; /* Nonzero means it is a mode for a low part | |
232 | that we should avoid changing when clearing | |
233 | the rest of the reg. */ | |
234 | struct movable *match; /* First entry for same value */ | |
235 | struct movable *forces; /* An insn that must be moved if this is */ | |
236 | struct movable *next; | |
237 | }; | |
238 | ||
239 | FILE *loop_dump_stream; | |
240 | ||
241 | /* Forward declarations. */ | |
242 | ||
243 | static void find_and_verify_loops (); | |
244 | static void mark_loop_jump (); | |
245 | static void prescan_loop (); | |
246 | static int reg_in_basic_block_p (); | |
247 | static int consec_sets_invariant_p (); | |
248 | static rtx libcall_other_reg (); | |
249 | static int labels_in_range_p (); | |
250 | static void count_loop_regs_set (); | |
251 | static void note_addr_stored (); | |
252 | static int loop_reg_used_before_p (); | |
253 | static void scan_loop (); | |
254 | static void replace_call_address (); | |
255 | static rtx skip_consec_insns (); | |
256 | static int libcall_benefit (); | |
257 | static void ignore_some_movables (); | |
258 | static void force_movables (); | |
259 | static void combine_movables (); | |
260 | static int rtx_equal_for_loop_p (); | |
261 | static void move_movables (); | |
262 | static void strength_reduce (); | |
263 | static int valid_initial_value_p (); | |
264 | static void find_mem_givs (); | |
265 | static void record_biv (); | |
266 | static void check_final_value (); | |
267 | static void record_giv (); | |
268 | static void update_giv_derive (); | |
269 | static void delete_insn_forces (); | |
270 | static int basic_induction_var (); | |
271 | static rtx simplify_giv_expr (); | |
272 | static int general_induction_var (); | |
273 | static int consec_sets_giv (); | |
274 | static int check_dbra_loop (); | |
275 | static rtx express_from (); | |
276 | static int combine_givs_p (); | |
277 | static void combine_givs (); | |
278 | static int product_cheap_p (); | |
279 | static int maybe_eliminate_biv (); | |
280 | static int maybe_eliminate_biv_1 (); | |
281 | static int last_use_this_basic_block (); | |
282 | static void record_initial (); | |
283 | static void update_reg_last_use (); | |
284 | \f | |
285 | /* Relative gain of eliminating various kinds of operations. */ | |
286 | int add_cost; | |
287 | #if 0 | |
288 | int shift_cost; | |
289 | int mult_cost; | |
290 | #endif | |
291 | ||
292 | /* Benefit penalty, if a giv is not replaceable, i.e. must emit an insn to | |
293 | copy the value of the strength reduced giv to its original register. */ | |
294 | int copy_cost; | |
295 | ||
296 | void | |
297 | init_loop () | |
298 | { | |
299 | char *free_point = (char *) oballoc (1); | |
300 | rtx reg = gen_rtx (REG, word_mode, 0); | |
301 | rtx pow2 = GEN_INT (32); | |
302 | rtx lea; | |
303 | int i; | |
304 | ||
305 | add_cost = rtx_cost (gen_rtx (PLUS, word_mode, reg, reg), SET); | |
306 | ||
307 | /* We multiply by 2 to reconcile the difference in scale between | |
308 | these two ways of computing costs. Otherwise the cost of a copy | |
309 | will be far less than the cost of an add. */ | |
310 | ||
311 | copy_cost = 2 * 2; | |
312 | ||
313 | /* Free the objects we just allocated. */ | |
314 | obfree (free_point); | |
315 | ||
316 | /* Initialize the obstack used for rtl in product_cheap_p. */ | |
317 | gcc_obstack_init (&temp_obstack); | |
318 | } | |
319 | \f | |
320 | /* Entry point of this file. Perform loop optimization | |
321 | on the current function. F is the first insn of the function | |
322 | and DUMPFILE is a stream for output of a trace of actions taken | |
323 | (or 0 if none should be output). */ | |
324 | ||
325 | void | |
326 | loop_optimize (f, dumpfile) | |
327 | /* f is the first instruction of a chain of insns for one function */ | |
328 | rtx f; | |
329 | FILE *dumpfile; | |
330 | { | |
331 | register rtx insn; | |
332 | register int i; | |
333 | rtx end; | |
334 | rtx last_insn; | |
335 | ||
336 | loop_dump_stream = dumpfile; | |
337 | ||
338 | init_recog_no_volatile (); | |
339 | init_alias_analysis (); | |
340 | ||
341 | max_reg_before_loop = max_reg_num (); | |
342 | ||
343 | moved_once = (char *) alloca (max_reg_before_loop); | |
344 | bzero (moved_once, max_reg_before_loop); | |
345 | ||
346 | regs_may_share = 0; | |
347 | ||
348 | /* Count the number of loops. */ | |
349 | ||
350 | max_loop_num = 0; | |
351 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
352 | { | |
353 | if (GET_CODE (insn) == NOTE | |
354 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
355 | max_loop_num++; | |
356 | } | |
357 | ||
358 | /* Don't waste time if no loops. */ | |
359 | if (max_loop_num == 0) | |
360 | return; | |
361 | ||
362 | /* Get size to use for tables indexed by uids. | |
363 | Leave some space for labels allocated by find_and_verify_loops. */ | |
364 | max_uid_for_loop = get_max_uid () + 1 + max_loop_num * 32; | |
365 | ||
366 | uid_luid = (int *) alloca (max_uid_for_loop * sizeof (int)); | |
367 | uid_loop_num = (int *) alloca (max_uid_for_loop * sizeof (int)); | |
368 | ||
369 | bzero (uid_luid, max_uid_for_loop * sizeof (int)); | |
370 | bzero (uid_loop_num, max_uid_for_loop * sizeof (int)); | |
371 | ||
372 | /* Allocate tables for recording each loop. We set each entry, so they need | |
373 | not be zeroed. */ | |
374 | loop_number_loop_starts = (rtx *) alloca (max_loop_num * sizeof (rtx)); | |
375 | loop_number_loop_ends = (rtx *) alloca (max_loop_num * sizeof (rtx)); | |
376 | loop_outer_loop = (int *) alloca (max_loop_num * sizeof (int)); | |
377 | loop_invalid = (char *) alloca (max_loop_num * sizeof (char)); | |
378 | loop_number_exit_labels = (rtx *) alloca (max_loop_num * sizeof (rtx)); | |
379 | ||
380 | /* Find and process each loop. | |
381 | First, find them, and record them in order of their beginnings. */ | |
382 | find_and_verify_loops (f); | |
383 | ||
384 | /* Now find all register lifetimes. This must be done after | |
385 | find_and_verify_loops, because it might reorder the insns in the | |
386 | function. */ | |
387 | reg_scan (f, max_reg_num (), 1); | |
388 | ||
389 | /* See if we went too far. */ | |
390 | if (get_max_uid () > max_uid_for_loop) | |
391 | abort (); | |
392 | ||
393 | /* Compute the mapping from uids to luids. | |
394 | LUIDs are numbers assigned to insns, like uids, | |
395 | except that luids increase monotonically through the code. | |
396 | Don't assign luids to line-number NOTEs, so that the distance in luids | |
397 | between two insns is not affected by -g. */ | |
398 | ||
399 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
400 | { | |
401 | last_insn = insn; | |
402 | if (GET_CODE (insn) != NOTE | |
403 | || NOTE_LINE_NUMBER (insn) <= 0) | |
404 | uid_luid[INSN_UID (insn)] = ++i; | |
405 | else | |
406 | /* Give a line number note the same luid as preceding insn. */ | |
407 | uid_luid[INSN_UID (insn)] = i; | |
408 | } | |
409 | ||
410 | max_luid = i + 1; | |
411 | ||
412 | /* Don't leave gaps in uid_luid for insns that have been | |
413 | deleted. It is possible that the first or last insn | |
414 | using some register has been deleted by cross-jumping. | |
415 | Make sure that uid_luid for that former insn's uid | |
416 | points to the general area where that insn used to be. */ | |
417 | for (i = 0; i < max_uid_for_loop; i++) | |
418 | { | |
419 | uid_luid[0] = uid_luid[i]; | |
420 | if (uid_luid[0] != 0) | |
421 | break; | |
422 | } | |
423 | for (i = 0; i < max_uid_for_loop; i++) | |
424 | if (uid_luid[i] == 0) | |
425 | uid_luid[i] = uid_luid[i - 1]; | |
426 | ||
427 | /* Create a mapping from loops to BLOCK tree nodes. */ | |
428 | if (flag_unroll_loops && write_symbols != NO_DEBUG) | |
429 | find_loop_tree_blocks (); | |
430 | ||
431 | /* Now scan the loops, last ones first, since this means inner ones are done | |
432 | before outer ones. */ | |
433 | for (i = max_loop_num-1; i >= 0; i--) | |
434 | if (! loop_invalid[i] && loop_number_loop_ends[i]) | |
435 | scan_loop (loop_number_loop_starts[i], loop_number_loop_ends[i], | |
436 | max_reg_num ()); | |
437 | ||
438 | /* If debugging and unrolling loops, we must replicate the tree nodes | |
439 | corresponding to the blocks inside the loop, so that the original one | |
440 | to one mapping will remain. */ | |
441 | if (flag_unroll_loops && write_symbols != NO_DEBUG) | |
442 | unroll_block_trees (); | |
443 | } | |
444 | \f | |
445 | /* Optimize one loop whose start is LOOP_START and end is END. | |
446 | LOOP_START is the NOTE_INSN_LOOP_BEG and END is the matching | |
447 | NOTE_INSN_LOOP_END. */ | |
448 | ||
449 | /* ??? Could also move memory writes out of loops if the destination address | |
450 | is invariant, the source is invariant, the memory write is not volatile, | |
451 | and if we can prove that no read inside the loop can read this address | |
452 | before the write occurs. If there is a read of this address after the | |
453 | write, then we can also mark the memory read as invariant. */ | |
454 | ||
455 | static void | |
456 | scan_loop (loop_start, end, nregs) | |
457 | rtx loop_start, end; | |
458 | int nregs; | |
459 | { | |
460 | register int i; | |
461 | register rtx p; | |
462 | /* 1 if we are scanning insns that could be executed zero times. */ | |
463 | int maybe_never = 0; | |
464 | /* 1 if we are scanning insns that might never be executed | |
465 | due to a subroutine call which might exit before they are reached. */ | |
466 | int call_passed = 0; | |
467 | /* For a rotated loop that is entered near the bottom, | |
468 | this is the label at the top. Otherwise it is zero. */ | |
469 | rtx loop_top = 0; | |
470 | /* Jump insn that enters the loop, or 0 if control drops in. */ | |
471 | rtx loop_entry_jump = 0; | |
472 | /* Place in the loop where control enters. */ | |
473 | rtx scan_start; | |
474 | /* Number of insns in the loop. */ | |
475 | int insn_count; | |
476 | int in_libcall = 0; | |
477 | int tem; | |
478 | rtx temp; | |
479 | /* The SET from an insn, if it is the only SET in the insn. */ | |
480 | rtx set, set1; | |
481 | /* Chain describing insns movable in current loop. */ | |
482 | struct movable *movables = 0; | |
483 | /* Last element in `movables' -- so we can add elements at the end. */ | |
484 | struct movable *last_movable = 0; | |
485 | /* Ratio of extra register life span we can justify | |
486 | for saving an instruction. More if loop doesn't call subroutines | |
487 | since in that case saving an insn makes more difference | |
488 | and more registers are available. */ | |
489 | int threshold; | |
490 | /* If we have calls, contains the insn in which a register was used | |
491 | if it was used exactly once; contains const0_rtx if it was used more | |
492 | than once. */ | |
493 | rtx *reg_single_usage = 0; | |
494 | ||
495 | n_times_set = (short *) alloca (nregs * sizeof (short)); | |
496 | n_times_used = (short *) alloca (nregs * sizeof (short)); | |
497 | may_not_optimize = (char *) alloca (nregs); | |
498 | ||
499 | /* Determine whether this loop starts with a jump down to a test at | |
500 | the end. This will occur for a small number of loops with a test | |
501 | that is too complex to duplicate in front of the loop. | |
502 | ||
503 | We search for the first insn or label in the loop, skipping NOTEs. | |
504 | However, we must be careful not to skip past a NOTE_INSN_LOOP_BEG | |
505 | (because we might have a loop executed only once that contains a | |
506 | loop which starts with a jump to its exit test) or a NOTE_INSN_LOOP_END | |
507 | (in case we have a degenerate loop). | |
508 | ||
509 | Note that if we mistakenly think that a loop is entered at the top | |
510 | when, in fact, it is entered at the exit test, the only effect will be | |
511 | slightly poorer optimization. Making the opposite error can generate | |
512 | incorrect code. Since very few loops now start with a jump to the | |
513 | exit test, the code here to detect that case is very conservative. */ | |
514 | ||
515 | for (p = NEXT_INSN (loop_start); | |
516 | p != end | |
517 | && GET_CODE (p) != CODE_LABEL && GET_RTX_CLASS (GET_CODE (p)) != 'i' | |
518 | && (GET_CODE (p) != NOTE | |
519 | || (NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_BEG | |
520 | && NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_END)); | |
521 | p = NEXT_INSN (p)) | |
522 | ; | |
523 | ||
524 | scan_start = p; | |
525 | ||
526 | /* Set up variables describing this loop. */ | |
527 | prescan_loop (loop_start, end); | |
528 | threshold = (loop_has_call ? 1 : 2) * (1 + n_non_fixed_regs); | |
529 | ||
530 | /* If loop has a jump before the first label, | |
531 | the true entry is the target of that jump. | |
532 | Start scan from there. | |
533 | But record in LOOP_TOP the place where the end-test jumps | |
534 | back to so we can scan that after the end of the loop. */ | |
535 | if (GET_CODE (p) == JUMP_INSN) | |
536 | { | |
537 | loop_entry_jump = p; | |
538 | ||
539 | /* Loop entry must be unconditional jump (and not a RETURN) */ | |
540 | if (simplejump_p (p) | |
541 | && JUMP_LABEL (p) != 0 | |
542 | /* Check to see whether the jump actually | |
543 | jumps out of the loop (meaning it's no loop). | |
544 | This case can happen for things like | |
545 | do {..} while (0). If this label was generated previously | |
546 | by loop, we can't tell anything about it and have to reject | |
547 | the loop. */ | |
548 | && INSN_UID (JUMP_LABEL (p)) < max_uid_for_loop | |
549 | && INSN_LUID (JUMP_LABEL (p)) >= INSN_LUID (loop_start) | |
550 | && INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (end)) | |
551 | { | |
552 | loop_top = next_label (scan_start); | |
553 | scan_start = JUMP_LABEL (p); | |
554 | } | |
555 | } | |
556 | ||
557 | /* If SCAN_START was an insn created by loop, we don't know its luid | |
558 | as required by loop_reg_used_before_p. So skip such loops. (This | |
559 | test may never be true, but it's best to play it safe.) | |
560 | ||
561 | Also, skip loops where we do not start scanning at a label. This | |
562 | test also rejects loops starting with a JUMP_INSN that failed the | |
563 | test above. */ | |
564 | ||
565 | if (INSN_UID (scan_start) >= max_uid_for_loop | |
566 | || GET_CODE (scan_start) != CODE_LABEL) | |
567 | { | |
568 | if (loop_dump_stream) | |
569 | fprintf (loop_dump_stream, "\nLoop from %d to %d is phony.\n\n", | |
570 | INSN_UID (loop_start), INSN_UID (end)); | |
571 | return; | |
572 | } | |
573 | ||
574 | /* Count number of times each reg is set during this loop. | |
575 | Set may_not_optimize[I] if it is not safe to move out | |
576 | the setting of register I. If this loop has calls, set | |
577 | reg_single_usage[I]. */ | |
578 | ||
579 | bzero (n_times_set, nregs * sizeof (short)); | |
580 | bzero (may_not_optimize, nregs); | |
581 | ||
582 | if (loop_has_call) | |
583 | { | |
584 | reg_single_usage = (rtx *) alloca (nregs * sizeof (rtx)); | |
585 | bzero (reg_single_usage, nregs * sizeof (rtx)); | |
586 | } | |
587 | ||
588 | count_loop_regs_set (loop_top ? loop_top : loop_start, end, | |
589 | may_not_optimize, reg_single_usage, &insn_count, nregs); | |
590 | ||
591 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
592 | may_not_optimize[i] = 1, n_times_set[i] = 1; | |
593 | bcopy (n_times_set, n_times_used, nregs * sizeof (short)); | |
594 | ||
595 | if (loop_dump_stream) | |
596 | { | |
597 | fprintf (loop_dump_stream, "\nLoop from %d to %d: %d real insns.\n", | |
598 | INSN_UID (loop_start), INSN_UID (end), insn_count); | |
599 | if (loop_continue) | |
600 | fprintf (loop_dump_stream, "Continue at insn %d.\n", | |
601 | INSN_UID (loop_continue)); | |
602 | } | |
603 | ||
604 | /* Scan through the loop finding insns that are safe to move. | |
605 | Set n_times_set negative for the reg being set, so that | |
606 | this reg will be considered invariant for subsequent insns. | |
607 | We consider whether subsequent insns use the reg | |
608 | in deciding whether it is worth actually moving. | |
609 | ||
610 | MAYBE_NEVER is nonzero if we have passed a conditional jump insn | |
611 | and therefore it is possible that the insns we are scanning | |
612 | would never be executed. At such times, we must make sure | |
613 | that it is safe to execute the insn once instead of zero times. | |
614 | When MAYBE_NEVER is 0, all insns will be executed at least once | |
615 | so that is not a problem. */ | |
616 | ||
617 | p = scan_start; | |
618 | while (1) | |
619 | { | |
620 | p = NEXT_INSN (p); | |
621 | /* At end of a straight-in loop, we are done. | |
622 | At end of a loop entered at the bottom, scan the top. */ | |
623 | if (p == scan_start) | |
624 | break; | |
625 | if (p == end) | |
626 | { | |
627 | if (loop_top != 0) | |
628 | p = NEXT_INSN (loop_top); | |
629 | else | |
630 | break; | |
631 | if (p == scan_start) | |
632 | break; | |
633 | } | |
634 | ||
635 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i' | |
636 | && find_reg_note (p, REG_LIBCALL, NULL_RTX)) | |
637 | in_libcall = 1; | |
638 | else if (GET_RTX_CLASS (GET_CODE (p)) == 'i' | |
639 | && find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
640 | in_libcall = 0; | |
641 | ||
642 | if (GET_CODE (p) == INSN | |
643 | && (set = single_set (p)) | |
644 | && GET_CODE (SET_DEST (set)) == REG | |
645 | && ! may_not_optimize[REGNO (SET_DEST (set))]) | |
646 | { | |
647 | int tem1 = 0; | |
648 | int tem2 = 0; | |
649 | int move_insn = 0; | |
650 | rtx src = SET_SRC (set); | |
651 | rtx dependencies = 0; | |
652 | ||
653 | /* Figure out what to use as a source of this insn. If a REG_EQUIV | |
654 | note is given or if a REG_EQUAL note with a constant operand is | |
655 | specified, use it as the source and mark that we should move | |
656 | this insn by calling emit_move_insn rather that duplicating the | |
657 | insn. | |
658 | ||
659 | Otherwise, only use the REG_EQUAL contents if a REG_RETVAL note | |
660 | is present. */ | |
661 | temp = find_reg_note (p, REG_EQUIV, NULL_RTX); | |
662 | if (temp) | |
663 | src = XEXP (temp, 0), move_insn = 1; | |
664 | else | |
665 | { | |
666 | temp = find_reg_note (p, REG_EQUAL, NULL_RTX); | |
667 | if (temp && CONSTANT_P (XEXP (temp, 0))) | |
668 | src = XEXP (temp, 0), move_insn = 1; | |
669 | if (temp && find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
670 | { | |
671 | src = XEXP (temp, 0); | |
672 | /* A libcall block can use regs that don't appear in | |
673 | the equivalent expression. To move the libcall, | |
674 | we must move those regs too. */ | |
675 | dependencies = libcall_other_reg (p, src); | |
676 | } | |
677 | } | |
678 | ||
679 | /* Don't try to optimize a register that was made | |
680 | by loop-optimization for an inner loop. | |
681 | We don't know its life-span, so we can't compute the benefit. */ | |
682 | if (REGNO (SET_DEST (set)) >= max_reg_before_loop) | |
683 | ; | |
684 | /* In order to move a register, we need to have one of three cases: | |
685 | (1) it is used only in the same basic block as the set | |
686 | (2) it is not a user variable. | |
687 | (3) the set is guaranteed to be executed once the loop starts, | |
688 | and the reg is not used until after that. */ | |
689 | else if (! ((! maybe_never | |
690 | && ! loop_reg_used_before_p (set, p, loop_start, | |
691 | scan_start, end)) | |
692 | || ! REG_USERVAR_P (SET_DEST (PATTERN (p))) | |
693 | || reg_in_basic_block_p (p, SET_DEST (PATTERN (p))))) | |
694 | ; | |
695 | else if ((tem = invariant_p (src)) | |
696 | && (dependencies == 0 | |
697 | || (tem2 = invariant_p (dependencies)) != 0) | |
698 | && (n_times_set[REGNO (SET_DEST (set))] == 1 | |
699 | || (tem1 | |
700 | = consec_sets_invariant_p (SET_DEST (set), | |
701 | n_times_set[REGNO (SET_DEST (set))], | |
702 | p))) | |
703 | /* If the insn can cause a trap (such as divide by zero), | |
704 | can't move it unless it's guaranteed to be executed | |
705 | once loop is entered. Even a function call might | |
706 | prevent the trap insn from being reached | |
707 | (since it might exit!) */ | |
708 | && ! ((maybe_never || call_passed) | |
709 | && may_trap_p (src))) | |
710 | { | |
711 | register struct movable *m; | |
712 | register int regno = REGNO (SET_DEST (set)); | |
713 | ||
714 | /* A potential lossage is where we have a case where two insns | |
715 | can be combined as long as they are both in the loop, but | |
716 | we move one of them outside the loop. For large loops, | |
717 | this can lose. The most common case of this is the address | |
718 | of a function being called. | |
719 | ||
720 | Therefore, if this register is marked as being used exactly | |
721 | once if we are in a loop with calls (a "large loop"), see if | |
722 | we can replace the usage of this register with the source | |
723 | of this SET. If we can, delete this insn. | |
724 | ||
725 | Don't do this if P has a REG_RETVAL note or if we have | |
726 | SMALL_REGISTER_CLASSES and SET_SRC is a hard register. */ | |
727 | ||
728 | if (reg_single_usage && reg_single_usage[regno] != 0 | |
729 | && reg_single_usage[regno] != const0_rtx | |
730 | && regno_first_uid[regno] == INSN_UID (p) | |
731 | && (regno_last_uid[regno] | |
732 | == INSN_UID (reg_single_usage[regno])) | |
733 | && n_times_set[REGNO (SET_DEST (set))] == 1 | |
734 | && ! side_effects_p (SET_SRC (set)) | |
735 | && ! find_reg_note (p, REG_RETVAL, NULL_RTX) | |
736 | #ifdef SMALL_REGISTER_CLASSES | |
737 | && ! (GET_CODE (SET_SRC (set)) == REG | |
738 | && REGNO (SET_SRC (set)) < FIRST_PSEUDO_REGISTER) | |
739 | #endif | |
740 | /* This test is not redundant; SET_SRC (set) might be | |
741 | a call-clobbered register and the life of REGNO | |
742 | might span a call. */ | |
743 | && ! modified_between_p (SET_SRC (set), p, | |
744 | reg_single_usage[regno]) | |
745 | && validate_replace_rtx (SET_DEST (set), SET_SRC (set), | |
746 | reg_single_usage[regno])) | |
747 | { | |
748 | /* Replace any usage in a REG_EQUAL note. */ | |
749 | REG_NOTES (reg_single_usage[regno]) | |
750 | = replace_rtx (REG_NOTES (reg_single_usage[regno]), | |
751 | SET_DEST (set), SET_SRC (set)); | |
752 | ||
753 | PUT_CODE (p, NOTE); | |
754 | NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED; | |
755 | NOTE_SOURCE_FILE (p) = 0; | |
756 | n_times_set[regno] = 0; | |
757 | continue; | |
758 | } | |
759 | ||
760 | m = (struct movable *) alloca (sizeof (struct movable)); | |
761 | m->next = 0; | |
762 | m->insn = p; | |
763 | m->set_src = src; | |
764 | m->dependencies = dependencies; | |
765 | m->set_dest = SET_DEST (set); | |
766 | m->force = 0; | |
767 | m->consec = n_times_set[REGNO (SET_DEST (set))] - 1; | |
768 | m->done = 0; | |
769 | m->forces = 0; | |
770 | m->partial = 0; | |
771 | m->move_insn = move_insn; | |
772 | m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0); | |
773 | m->savemode = VOIDmode; | |
774 | m->regno = regno; | |
775 | /* Set M->cond if either invariant_p or consec_sets_invariant_p | |
776 | returned 2 (only conditionally invariant). */ | |
777 | m->cond = ((tem | tem1 | tem2) > 1); | |
778 | m->global = (uid_luid[regno_last_uid[regno]] > INSN_LUID (end) | |
779 | || uid_luid[regno_first_uid[regno]] < INSN_LUID (loop_start)); | |
780 | m->match = 0; | |
781 | m->lifetime = (uid_luid[regno_last_uid[regno]] | |
782 | - uid_luid[regno_first_uid[regno]]); | |
783 | m->savings = n_times_used[regno]; | |
784 | if (find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
785 | m->savings += libcall_benefit (p); | |
786 | n_times_set[regno] = move_insn ? -2 : -1; | |
787 | /* Add M to the end of the chain MOVABLES. */ | |
788 | if (movables == 0) | |
789 | movables = m; | |
790 | else | |
791 | last_movable->next = m; | |
792 | last_movable = m; | |
793 | ||
794 | if (m->consec > 0) | |
795 | { | |
796 | /* Skip this insn, not checking REG_LIBCALL notes. */ | |
797 | p = NEXT_INSN (p); | |
798 | /* Skip the consecutive insns, if there are any. */ | |
799 | p = skip_consec_insns (p, m->consec); | |
800 | /* Back up to the last insn of the consecutive group. */ | |
801 | p = prev_nonnote_insn (p); | |
802 | ||
803 | /* We must now reset m->move_insn, m->is_equiv, and possibly | |
804 | m->set_src to correspond to the effects of all the | |
805 | insns. */ | |
806 | temp = find_reg_note (p, REG_EQUIV, NULL_RTX); | |
807 | if (temp) | |
808 | m->set_src = XEXP (temp, 0), m->move_insn = 1; | |
809 | else | |
810 | { | |
811 | temp = find_reg_note (p, REG_EQUAL, NULL_RTX); | |
812 | if (temp && CONSTANT_P (XEXP (temp, 0))) | |
813 | m->set_src = XEXP (temp, 0), m->move_insn = 1; | |
814 | else | |
815 | m->move_insn = 0; | |
816 | ||
817 | } | |
818 | m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0); | |
819 | } | |
820 | } | |
821 | /* If this register is always set within a STRICT_LOW_PART | |
822 | or set to zero, then its high bytes are constant. | |
823 | So clear them outside the loop and within the loop | |
824 | just load the low bytes. | |
825 | We must check that the machine has an instruction to do so. | |
826 | Also, if the value loaded into the register | |
827 | depends on the same register, this cannot be done. */ | |
828 | else if (SET_SRC (set) == const0_rtx | |
829 | && GET_CODE (NEXT_INSN (p)) == INSN | |
830 | && (set1 = single_set (NEXT_INSN (p))) | |
831 | && GET_CODE (set1) == SET | |
832 | && (GET_CODE (SET_DEST (set1)) == STRICT_LOW_PART) | |
833 | && (GET_CODE (XEXP (SET_DEST (set1), 0)) == SUBREG) | |
834 | && (SUBREG_REG (XEXP (SET_DEST (set1), 0)) | |
835 | == SET_DEST (set)) | |
836 | && !reg_mentioned_p (SET_DEST (set), SET_SRC (set1))) | |
837 | { | |
838 | register int regno = REGNO (SET_DEST (set)); | |
839 | if (n_times_set[regno] == 2) | |
840 | { | |
841 | register struct movable *m; | |
842 | m = (struct movable *) alloca (sizeof (struct movable)); | |
843 | m->next = 0; | |
844 | m->insn = p; | |
845 | m->set_dest = SET_DEST (set); | |
846 | m->dependencies = 0; | |
847 | m->force = 0; | |
848 | m->consec = 0; | |
849 | m->done = 0; | |
850 | m->forces = 0; | |
851 | m->move_insn = 0; | |
852 | m->partial = 1; | |
853 | /* If the insn may not be executed on some cycles, | |
854 | we can't clear the whole reg; clear just high part. | |
855 | Not even if the reg is used only within this loop. | |
856 | Consider this: | |
857 | while (1) | |
858 | while (s != t) { | |
859 | if (foo ()) x = *s; | |
860 | use (x); | |
861 | } | |
862 | Clearing x before the inner loop could clobber a value | |
863 | being saved from the last time around the outer loop. | |
864 | However, if the reg is not used outside this loop | |
865 | and all uses of the register are in the same | |
866 | basic block as the store, there is no problem. | |
867 | ||
868 | If this insn was made by loop, we don't know its | |
869 | INSN_LUID and hence must make a conservative | |
870 | assumption. */ | |
871 | m->global = (INSN_UID (p) >= max_uid_for_loop | |
872 | || (uid_luid[regno_last_uid[regno]] | |
873 | > INSN_LUID (end)) | |
874 | || (uid_luid[regno_first_uid[regno]] | |
875 | < INSN_LUID (p)) | |
876 | || (labels_in_range_p | |
877 | (p, uid_luid[regno_first_uid[regno]]))); | |
878 | if (maybe_never && m->global) | |
879 | m->savemode = GET_MODE (SET_SRC (set1)); | |
880 | else | |
881 | m->savemode = VOIDmode; | |
882 | m->regno = regno; | |
883 | m->cond = 0; | |
884 | m->match = 0; | |
885 | m->lifetime = (uid_luid[regno_last_uid[regno]] | |
886 | - uid_luid[regno_first_uid[regno]]); | |
887 | m->savings = 1; | |
888 | n_times_set[regno] = -1; | |
889 | /* Add M to the end of the chain MOVABLES. */ | |
890 | if (movables == 0) | |
891 | movables = m; | |
892 | else | |
893 | last_movable->next = m; | |
894 | last_movable = m; | |
895 | } | |
896 | } | |
897 | } | |
898 | /* Past a call insn, we get to insns which might not be executed | |
899 | because the call might exit. This matters for insns that trap. | |
900 | Call insns inside a REG_LIBCALL/REG_RETVAL block always return, | |
901 | so they don't count. */ | |
902 | else if (GET_CODE (p) == CALL_INSN && ! in_libcall) | |
903 | call_passed = 1; | |
904 | /* Past a label or a jump, we get to insns for which we | |
905 | can't count on whether or how many times they will be | |
906 | executed during each iteration. Therefore, we can | |
907 | only move out sets of trivial variables | |
908 | (those not used after the loop). */ | |
909 | /* This code appears in three places, once in scan_loop, and twice | |
910 | in strength_reduce. */ | |
911 | else if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) | |
912 | /* If we enter the loop in the middle, and scan around to the | |
913 | beginning, don't set maybe_never for that. This must be an | |
914 | unconditional jump, otherwise the code at the top of the | |
915 | loop might never be executed. Unconditional jumps are | |
916 | followed a by barrier then loop end. */ | |
917 | && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top | |
918 | && NEXT_INSN (NEXT_INSN (p)) == end | |
919 | && simplejump_p (p))) | |
920 | maybe_never = 1; | |
921 | /* At the virtual top of a converted loop, insns are again known to | |
922 | be executed: logically, the loop begins here even though the exit | |
923 | code has been duplicated. */ | |
924 | else if (GET_CODE (p) == NOTE | |
925 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP) | |
926 | maybe_never = call_passed = 0; | |
927 | } | |
928 | ||
929 | /* If one movable subsumes another, ignore that other. */ | |
930 | ||
931 | ignore_some_movables (movables); | |
932 | ||
933 | /* For each movable insn, see if the reg that it loads | |
934 | leads when it dies right into another conditionally movable insn. | |
935 | If so, record that the second insn "forces" the first one, | |
936 | since the second can be moved only if the first is. */ | |
937 | ||
938 | force_movables (movables); | |
939 | ||
940 | /* See if there are multiple movable insns that load the same value. | |
941 | If there are, make all but the first point at the first one | |
942 | through the `match' field, and add the priorities of them | |
943 | all together as the priority of the first. */ | |
944 | ||
945 | combine_movables (movables, nregs); | |
946 | ||
947 | /* Now consider each movable insn to decide whether it is worth moving. | |
948 | Store 0 in n_times_set for each reg that is moved. */ | |
949 | ||
950 | move_movables (movables, threshold, | |
951 | insn_count, loop_start, end, nregs); | |
952 | ||
953 | /* Now candidates that still are negative are those not moved. | |
954 | Change n_times_set to indicate that those are not actually invariant. */ | |
955 | for (i = 0; i < nregs; i++) | |
956 | if (n_times_set[i] < 0) | |
957 | n_times_set[i] = n_times_used[i]; | |
958 | ||
959 | if (flag_strength_reduce) | |
960 | strength_reduce (scan_start, end, loop_top, | |
961 | insn_count, loop_start, end); | |
962 | } | |
963 | \f | |
964 | /* Add elements to *OUTPUT to record all the pseudo-regs | |
965 | mentioned in IN_THIS but not mentioned in NOT_IN_THIS. */ | |
966 | ||
967 | void | |
968 | record_excess_regs (in_this, not_in_this, output) | |
969 | rtx in_this, not_in_this; | |
970 | rtx *output; | |
971 | { | |
972 | enum rtx_code code; | |
973 | char *fmt; | |
974 | int i; | |
975 | ||
976 | code = GET_CODE (in_this); | |
977 | ||
978 | switch (code) | |
979 | { | |
980 | case PC: | |
981 | case CC0: | |
982 | case CONST_INT: | |
983 | case CONST_DOUBLE: | |
984 | case CONST: | |
985 | case SYMBOL_REF: | |
986 | case LABEL_REF: | |
987 | return; | |
988 | ||
989 | case REG: | |
990 | if (REGNO (in_this) >= FIRST_PSEUDO_REGISTER | |
991 | && ! reg_mentioned_p (in_this, not_in_this)) | |
992 | *output = gen_rtx (EXPR_LIST, VOIDmode, in_this, *output); | |
993 | return; | |
994 | } | |
995 | ||
996 | fmt = GET_RTX_FORMAT (code); | |
997 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
998 | { | |
999 | int j; | |
1000 | ||
1001 | switch (fmt[i]) | |
1002 | { | |
1003 | case 'E': | |
1004 | for (j = 0; j < XVECLEN (in_this, i); j++) | |
1005 | record_excess_regs (XVECEXP (in_this, i, j), not_in_this, output); | |
1006 | break; | |
1007 | ||
1008 | case 'e': | |
1009 | record_excess_regs (XEXP (in_this, i), not_in_this, output); | |
1010 | break; | |
1011 | } | |
1012 | } | |
1013 | } | |
1014 | \f | |
1015 | /* Check what regs are referred to in the libcall block ending with INSN, | |
1016 | aside from those mentioned in the equivalent value. | |
1017 | If there are none, return 0. | |
1018 | If there are one or more, return an EXPR_LIST containing all of them. */ | |
1019 | ||
1020 | static rtx | |
1021 | libcall_other_reg (insn, equiv) | |
1022 | rtx insn, equiv; | |
1023 | { | |
1024 | rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX); | |
1025 | rtx p = XEXP (note, 0); | |
1026 | rtx output = 0; | |
1027 | ||
1028 | /* First, find all the regs used in the libcall block | |
1029 | that are not mentioned as inputs to the result. */ | |
1030 | ||
1031 | while (p != insn) | |
1032 | { | |
1033 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
1034 | || GET_CODE (p) == CALL_INSN) | |
1035 | record_excess_regs (PATTERN (p), equiv, &output); | |
1036 | p = NEXT_INSN (p); | |
1037 | } | |
1038 | ||
1039 | return output; | |
1040 | } | |
1041 | \f | |
1042 | /* Return 1 if all uses of REG | |
1043 | are between INSN and the end of the basic block. */ | |
1044 | ||
1045 | static int | |
1046 | reg_in_basic_block_p (insn, reg) | |
1047 | rtx insn, reg; | |
1048 | { | |
1049 | int regno = REGNO (reg); | |
1050 | rtx p; | |
1051 | ||
1052 | if (regno_first_uid[regno] != INSN_UID (insn)) | |
1053 | return 0; | |
1054 | ||
1055 | /* Search this basic block for the already recorded last use of the reg. */ | |
1056 | for (p = insn; p; p = NEXT_INSN (p)) | |
1057 | { | |
1058 | switch (GET_CODE (p)) | |
1059 | { | |
1060 | case NOTE: | |
1061 | break; | |
1062 | ||
1063 | case INSN: | |
1064 | case CALL_INSN: | |
1065 | /* Ordinary insn: if this is the last use, we win. */ | |
1066 | if (regno_last_uid[regno] == INSN_UID (p)) | |
1067 | return 1; | |
1068 | break; | |
1069 | ||
1070 | case JUMP_INSN: | |
1071 | /* Jump insn: if this is the last use, we win. */ | |
1072 | if (regno_last_uid[regno] == INSN_UID (p)) | |
1073 | return 1; | |
1074 | /* Otherwise, it's the end of the basic block, so we lose. */ | |
1075 | return 0; | |
1076 | ||
1077 | case CODE_LABEL: | |
1078 | case BARRIER: | |
1079 | /* It's the end of the basic block, so we lose. */ | |
1080 | return 0; | |
1081 | } | |
1082 | } | |
1083 | ||
1084 | /* The "last use" doesn't follow the "first use"?? */ | |
1085 | abort (); | |
1086 | } | |
1087 | \f | |
1088 | /* Compute the benefit of eliminating the insns in the block whose | |
1089 | last insn is LAST. This may be a group of insns used to compute a | |
1090 | value directly or can contain a library call. */ | |
1091 | ||
1092 | static int | |
1093 | libcall_benefit (last) | |
1094 | rtx last; | |
1095 | { | |
1096 | rtx insn; | |
1097 | int benefit = 0; | |
1098 | ||
1099 | for (insn = XEXP (find_reg_note (last, REG_RETVAL, NULL_RTX), 0); | |
1100 | insn != last; insn = NEXT_INSN (insn)) | |
1101 | { | |
1102 | if (GET_CODE (insn) == CALL_INSN) | |
1103 | benefit += 10; /* Assume at least this many insns in a library | |
1104 | routine. */ | |
1105 | else if (GET_CODE (insn) == INSN | |
1106 | && GET_CODE (PATTERN (insn)) != USE | |
1107 | && GET_CODE (PATTERN (insn)) != CLOBBER) | |
1108 | benefit++; | |
1109 | } | |
1110 | ||
1111 | return benefit; | |
1112 | } | |
1113 | \f | |
1114 | /* Skip COUNT insns from INSN, counting library calls as 1 insn. */ | |
1115 | ||
1116 | static rtx | |
1117 | skip_consec_insns (insn, count) | |
1118 | rtx insn; | |
1119 | int count; | |
1120 | { | |
1121 | for (; count > 0; count--) | |
1122 | { | |
1123 | rtx temp; | |
1124 | ||
1125 | /* If first insn of libcall sequence, skip to end. */ | |
1126 | /* Do this at start of loop, since INSN is guaranteed to | |
1127 | be an insn here. */ | |
1128 | if (GET_CODE (insn) != NOTE | |
1129 | && (temp = find_reg_note (insn, REG_LIBCALL, NULL_RTX))) | |
1130 | insn = XEXP (temp, 0); | |
1131 | ||
1132 | do insn = NEXT_INSN (insn); | |
1133 | while (GET_CODE (insn) == NOTE); | |
1134 | } | |
1135 | ||
1136 | return insn; | |
1137 | } | |
1138 | ||
1139 | /* Ignore any movable whose insn falls within a libcall | |
1140 | which is part of another movable. | |
1141 | We make use of the fact that the movable for the libcall value | |
1142 | was made later and so appears later on the chain. */ | |
1143 | ||
1144 | static void | |
1145 | ignore_some_movables (movables) | |
1146 | struct movable *movables; | |
1147 | { | |
1148 | register struct movable *m, *m1; | |
1149 | ||
1150 | for (m = movables; m; m = m->next) | |
1151 | { | |
1152 | /* Is this a movable for the value of a libcall? */ | |
1153 | rtx note = find_reg_note (m->insn, REG_RETVAL, NULL_RTX); | |
1154 | if (note) | |
1155 | { | |
1156 | rtx insn; | |
1157 | /* Check for earlier movables inside that range, | |
1158 | and mark them invalid. We cannot use LUIDs here because | |
1159 | insns created by loop.c for prior loops don't have LUIDs. | |
1160 | Rather than reject all such insns from movables, we just | |
1161 | explicitly check each insn in the libcall (since invariant | |
1162 | libcalls aren't that common). */ | |
1163 | for (insn = XEXP (note, 0); insn != m->insn; insn = NEXT_INSN (insn)) | |
1164 | for (m1 = movables; m1 != m; m1 = m1->next) | |
1165 | if (m1->insn == insn) | |
1166 | m1->done = 1; | |
1167 | } | |
1168 | } | |
1169 | } | |
1170 | ||
1171 | /* For each movable insn, see if the reg that it loads | |
1172 | leads when it dies right into another conditionally movable insn. | |
1173 | If so, record that the second insn "forces" the first one, | |
1174 | since the second can be moved only if the first is. */ | |
1175 | ||
1176 | static void | |
1177 | force_movables (movables) | |
1178 | struct movable *movables; | |
1179 | { | |
1180 | register struct movable *m, *m1; | |
1181 | for (m1 = movables; m1; m1 = m1->next) | |
1182 | /* Omit this if moving just the (SET (REG) 0) of a zero-extend. */ | |
1183 | if (!m1->partial && !m1->done) | |
1184 | { | |
1185 | int regno = m1->regno; | |
1186 | for (m = m1->next; m; m = m->next) | |
1187 | /* ??? Could this be a bug? What if CSE caused the | |
1188 | register of M1 to be used after this insn? | |
1189 | Since CSE does not update regno_last_uid, | |
1190 | this insn M->insn might not be where it dies. | |
1191 | But very likely this doesn't matter; what matters is | |
1192 | that M's reg is computed from M1's reg. */ | |
1193 | if (INSN_UID (m->insn) == regno_last_uid[regno] | |
1194 | && !m->done) | |
1195 | break; | |
1196 | if (m != 0 && m->set_src == m1->set_dest | |
1197 | /* If m->consec, m->set_src isn't valid. */ | |
1198 | && m->consec == 0) | |
1199 | m = 0; | |
1200 | ||
1201 | /* Increase the priority of the moving the first insn | |
1202 | since it permits the second to be moved as well. */ | |
1203 | if (m != 0) | |
1204 | { | |
1205 | m->forces = m1; | |
1206 | m1->lifetime += m->lifetime; | |
1207 | m1->savings += m1->savings; | |
1208 | } | |
1209 | } | |
1210 | } | |
1211 | \f | |
1212 | /* Find invariant expressions that are equal and can be combined into | |
1213 | one register. */ | |
1214 | ||
1215 | static void | |
1216 | combine_movables (movables, nregs) | |
1217 | struct movable *movables; | |
1218 | int nregs; | |
1219 | { | |
1220 | register struct movable *m; | |
1221 | char *matched_regs = (char *) alloca (nregs); | |
1222 | enum machine_mode mode; | |
1223 | ||
1224 | /* Regs that are set more than once are not allowed to match | |
1225 | or be matched. I'm no longer sure why not. */ | |
1226 | /* Perhaps testing m->consec_sets would be more appropriate here? */ | |
1227 | ||
1228 | for (m = movables; m; m = m->next) | |
1229 | if (m->match == 0 && n_times_used[m->regno] == 1 && !m->partial) | |
1230 | { | |
1231 | register struct movable *m1; | |
1232 | int regno = m->regno; | |
1233 | rtx reg_note, reg_note1; | |
1234 | ||
1235 | bzero (matched_regs, nregs); | |
1236 | matched_regs[regno] = 1; | |
1237 | ||
1238 | for (m1 = movables; m1; m1 = m1->next) | |
1239 | if (m != m1 && m1->match == 0 && n_times_used[m1->regno] == 1 | |
1240 | /* A reg used outside the loop mustn't be eliminated. */ | |
1241 | && !m1->global | |
1242 | /* A reg used for zero-extending mustn't be eliminated. */ | |
1243 | && !m1->partial | |
1244 | && (matched_regs[m1->regno] | |
1245 | || | |
1246 | ( | |
1247 | /* Can combine regs with different modes loaded from the | |
1248 | same constant only if the modes are the same or | |
1249 | if both are integer modes with M wider or the same | |
1250 | width as M1. The check for integer is redundant, but | |
1251 | safe, since the only case of differing destination | |
1252 | modes with equal sources is when both sources are | |
1253 | VOIDmode, i.e., CONST_INT. */ | |
1254 | (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest) | |
1255 | || (GET_MODE_CLASS (GET_MODE (m->set_dest)) == MODE_INT | |
1256 | && GET_MODE_CLASS (GET_MODE (m1->set_dest)) == MODE_INT | |
1257 | && (GET_MODE_BITSIZE (GET_MODE (m->set_dest)) | |
1258 | >= GET_MODE_BITSIZE (GET_MODE (m1->set_dest))))) | |
1259 | /* See if the source of M1 says it matches M. */ | |
1260 | && ((GET_CODE (m1->set_src) == REG | |
1261 | && matched_regs[REGNO (m1->set_src)]) | |
1262 | || rtx_equal_for_loop_p (m->set_src, m1->set_src, | |
1263 | movables)))) | |
1264 | && ((m->dependencies == m1->dependencies) | |
1265 | || rtx_equal_p (m->dependencies, m1->dependencies))) | |
1266 | { | |
1267 | m->lifetime += m1->lifetime; | |
1268 | m->savings += m1->savings; | |
1269 | m1->done = 1; | |
1270 | m1->match = m; | |
1271 | matched_regs[m1->regno] = 1; | |
1272 | } | |
1273 | } | |
1274 | ||
1275 | /* Now combine the regs used for zero-extension. | |
1276 | This can be done for those not marked `global' | |
1277 | provided their lives don't overlap. */ | |
1278 | ||
1279 | for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode; | |
1280 | mode = GET_MODE_WIDER_MODE (mode)) | |
1281 | { | |
1282 | register struct movable *m0 = 0; | |
1283 | ||
1284 | /* Combine all the registers for extension from mode MODE. | |
1285 | Don't combine any that are used outside this loop. */ | |
1286 | for (m = movables; m; m = m->next) | |
1287 | if (m->partial && ! m->global | |
1288 | && mode == GET_MODE (SET_SRC (PATTERN (NEXT_INSN (m->insn))))) | |
1289 | { | |
1290 | register struct movable *m1; | |
1291 | int first = uid_luid[regno_first_uid[m->regno]]; | |
1292 | int last = uid_luid[regno_last_uid[m->regno]]; | |
1293 | ||
1294 | if (m0 == 0) | |
1295 | { | |
1296 | /* First one: don't check for overlap, just record it. */ | |
1297 | m0 = m; | |
1298 | continue; | |
1299 | } | |
1300 | ||
1301 | /* Make sure they extend to the same mode. | |
1302 | (Almost always true.) */ | |
1303 | if (GET_MODE (m->set_dest) != GET_MODE (m0->set_dest)) | |
1304 | continue; | |
1305 | ||
1306 | /* We already have one: check for overlap with those | |
1307 | already combined together. */ | |
1308 | for (m1 = movables; m1 != m; m1 = m1->next) | |
1309 | if (m1 == m0 || (m1->partial && m1->match == m0)) | |
1310 | if (! (uid_luid[regno_first_uid[m1->regno]] > last | |
1311 | || uid_luid[regno_last_uid[m1->regno]] < first)) | |
1312 | goto overlap; | |
1313 | ||
1314 | /* No overlap: we can combine this with the others. */ | |
1315 | m0->lifetime += m->lifetime; | |
1316 | m0->savings += m->savings; | |
1317 | m->done = 1; | |
1318 | m->match = m0; | |
1319 | ||
1320 | overlap: ; | |
1321 | } | |
1322 | } | |
1323 | } | |
1324 | \f | |
1325 | /* Return 1 if regs X and Y will become the same if moved. */ | |
1326 | ||
1327 | static int | |
1328 | regs_match_p (x, y, movables) | |
1329 | rtx x, y; | |
1330 | struct movable *movables; | |
1331 | { | |
1332 | int xn = REGNO (x); | |
1333 | int yn = REGNO (y); | |
1334 | struct movable *mx, *my; | |
1335 | ||
1336 | for (mx = movables; mx; mx = mx->next) | |
1337 | if (mx->regno == xn) | |
1338 | break; | |
1339 | ||
1340 | for (my = movables; my; my = my->next) | |
1341 | if (my->regno == yn) | |
1342 | break; | |
1343 | ||
1344 | return (mx && my | |
1345 | && ((mx->match == my->match && mx->match != 0) | |
1346 | || mx->match == my | |
1347 | || mx == my->match)); | |
1348 | } | |
1349 | ||
1350 | /* Return 1 if X and Y are identical-looking rtx's. | |
1351 | This is the Lisp function EQUAL for rtx arguments. | |
1352 | ||
1353 | If two registers are matching movables or a movable register and an | |
1354 | equivalent constant, consider them equal. */ | |
1355 | ||
1356 | static int | |
1357 | rtx_equal_for_loop_p (x, y, movables) | |
1358 | rtx x, y; | |
1359 | struct movable *movables; | |
1360 | { | |
1361 | register int i; | |
1362 | register int j; | |
1363 | register struct movable *m; | |
1364 | register enum rtx_code code; | |
1365 | register char *fmt; | |
1366 | ||
1367 | if (x == y) | |
1368 | return 1; | |
1369 | if (x == 0 || y == 0) | |
1370 | return 0; | |
1371 | ||
1372 | code = GET_CODE (x); | |
1373 | ||
1374 | /* If we have a register and a constant, they may sometimes be | |
1375 | equal. */ | |
1376 | if (GET_CODE (x) == REG && n_times_set[REGNO (x)] == -2 | |
1377 | && CONSTANT_P (y)) | |
1378 | for (m = movables; m; m = m->next) | |
1379 | if (m->move_insn && m->regno == REGNO (x) | |
1380 | && rtx_equal_p (m->set_src, y)) | |
1381 | return 1; | |
1382 | ||
1383 | else if (GET_CODE (y) == REG && n_times_set[REGNO (y)] == -2 | |
1384 | && CONSTANT_P (x)) | |
1385 | for (m = movables; m; m = m->next) | |
1386 | if (m->move_insn && m->regno == REGNO (y) | |
1387 | && rtx_equal_p (m->set_src, x)) | |
1388 | return 1; | |
1389 | ||
1390 | /* Otherwise, rtx's of different codes cannot be equal. */ | |
1391 | if (code != GET_CODE (y)) | |
1392 | return 0; | |
1393 | ||
1394 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. | |
1395 | (REG:SI x) and (REG:HI x) are NOT equivalent. */ | |
1396 | ||
1397 | if (GET_MODE (x) != GET_MODE (y)) | |
1398 | return 0; | |
1399 | ||
1400 | /* These three types of rtx's can be compared nonrecursively. */ | |
1401 | if (code == REG) | |
1402 | return (REGNO (x) == REGNO (y) || regs_match_p (x, y, movables)); | |
1403 | ||
1404 | if (code == LABEL_REF) | |
1405 | return XEXP (x, 0) == XEXP (y, 0); | |
1406 | if (code == SYMBOL_REF) | |
1407 | return XSTR (x, 0) == XSTR (y, 0); | |
1408 | ||
1409 | /* Compare the elements. If any pair of corresponding elements | |
1410 | fail to match, return 0 for the whole things. */ | |
1411 | ||
1412 | fmt = GET_RTX_FORMAT (code); | |
1413 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1414 | { | |
1415 | switch (fmt[i]) | |
1416 | { | |
1417 | case 'w': | |
1418 | if (XWINT (x, i) != XWINT (y, i)) | |
1419 | return 0; | |
1420 | break; | |
1421 | ||
1422 | case 'i': | |
1423 | if (XINT (x, i) != XINT (y, i)) | |
1424 | return 0; | |
1425 | break; | |
1426 | ||
1427 | case 'E': | |
1428 | /* Two vectors must have the same length. */ | |
1429 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1430 | return 0; | |
1431 | ||
1432 | /* And the corresponding elements must match. */ | |
1433 | for (j = 0; j < XVECLEN (x, i); j++) | |
1434 | if (rtx_equal_for_loop_p (XVECEXP (x, i, j), XVECEXP (y, i, j), movables) == 0) | |
1435 | return 0; | |
1436 | break; | |
1437 | ||
1438 | case 'e': | |
1439 | if (rtx_equal_for_loop_p (XEXP (x, i), XEXP (y, i), movables) == 0) | |
1440 | return 0; | |
1441 | break; | |
1442 | ||
1443 | case 's': | |
1444 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1445 | return 0; | |
1446 | break; | |
1447 | ||
1448 | case 'u': | |
1449 | /* These are just backpointers, so they don't matter. */ | |
1450 | break; | |
1451 | ||
1452 | case '0': | |
1453 | break; | |
1454 | ||
1455 | /* It is believed that rtx's at this level will never | |
1456 | contain anything but integers and other rtx's, | |
1457 | except for within LABEL_REFs and SYMBOL_REFs. */ | |
1458 | default: | |
1459 | abort (); | |
1460 | } | |
1461 | } | |
1462 | return 1; | |
1463 | } | |
1464 | \f | |
1465 | /* If X contains any LABEL_REF's, add REG_LABEL notes for them to all | |
1466 | insns in INSNS which use thet reference. */ | |
1467 | ||
1468 | static void | |
1469 | add_label_notes (x, insns) | |
1470 | rtx x; | |
1471 | rtx insns; | |
1472 | { | |
1473 | enum rtx_code code = GET_CODE (x); | |
1474 | int i, j; | |
1475 | char *fmt; | |
1476 | rtx insn; | |
1477 | ||
1478 | if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) | |
1479 | { | |
1480 | for (insn = insns; insn; insn = NEXT_INSN (insn)) | |
1481 | if (reg_mentioned_p (XEXP (x, 0), insn)) | |
1482 | REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, XEXP (x, 0), | |
1483 | REG_NOTES (insn)); | |
1484 | return; | |
1485 | } | |
1486 | ||
1487 | fmt = GET_RTX_FORMAT (code); | |
1488 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1489 | { | |
1490 | if (fmt[i] == 'e') | |
1491 | add_label_notes (XEXP (x, i), insns); | |
1492 | else if (fmt[i] == 'E') | |
1493 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
1494 | add_label_notes (XVECEXP (x, i, j), insns); | |
1495 | } | |
1496 | } | |
1497 | \f | |
1498 | /* Scan MOVABLES, and move the insns that deserve to be moved. | |
1499 | If two matching movables are combined, replace one reg with the | |
1500 | other throughout. */ | |
1501 | ||
1502 | static void | |
1503 | move_movables (movables, threshold, insn_count, loop_start, end, nregs) | |
1504 | struct movable *movables; | |
1505 | int threshold; | |
1506 | int insn_count; | |
1507 | rtx loop_start; | |
1508 | rtx end; | |
1509 | int nregs; | |
1510 | { | |
1511 | rtx new_start = 0; | |
1512 | register struct movable *m; | |
1513 | register rtx p; | |
1514 | /* Map of pseudo-register replacements to handle combining | |
1515 | when we move several insns that load the same value | |
1516 | into different pseudo-registers. */ | |
1517 | rtx *reg_map = (rtx *) alloca (nregs * sizeof (rtx)); | |
1518 | char *already_moved = (char *) alloca (nregs); | |
1519 | ||
1520 | bzero (already_moved, nregs); | |
1521 | bzero (reg_map, nregs * sizeof (rtx)); | |
1522 | ||
1523 | num_movables = 0; | |
1524 | ||
1525 | for (m = movables; m; m = m->next) | |
1526 | { | |
1527 | /* Describe this movable insn. */ | |
1528 | ||
1529 | if (loop_dump_stream) | |
1530 | { | |
1531 | fprintf (loop_dump_stream, "Insn %d: regno %d (life %d), ", | |
1532 | INSN_UID (m->insn), m->regno, m->lifetime); | |
1533 | if (m->consec > 0) | |
1534 | fprintf (loop_dump_stream, "consec %d, ", m->consec); | |
1535 | if (m->cond) | |
1536 | fprintf (loop_dump_stream, "cond "); | |
1537 | if (m->force) | |
1538 | fprintf (loop_dump_stream, "force "); | |
1539 | if (m->global) | |
1540 | fprintf (loop_dump_stream, "global "); | |
1541 | if (m->done) | |
1542 | fprintf (loop_dump_stream, "done "); | |
1543 | if (m->move_insn) | |
1544 | fprintf (loop_dump_stream, "move-insn "); | |
1545 | if (m->match) | |
1546 | fprintf (loop_dump_stream, "matches %d ", | |
1547 | INSN_UID (m->match->insn)); | |
1548 | if (m->forces) | |
1549 | fprintf (loop_dump_stream, "forces %d ", | |
1550 | INSN_UID (m->forces->insn)); | |
1551 | } | |
1552 | ||
1553 | /* Count movables. Value used in heuristics in strength_reduce. */ | |
1554 | num_movables++; | |
1555 | ||
1556 | /* Ignore the insn if it's already done (it matched something else). | |
1557 | Otherwise, see if it is now safe to move. */ | |
1558 | ||
1559 | if (!m->done | |
1560 | && (! m->cond | |
1561 | || (1 == invariant_p (m->set_src) | |
1562 | && (m->dependencies == 0 | |
1563 | || 1 == invariant_p (m->dependencies)) | |
1564 | && (m->consec == 0 | |
1565 | || 1 == consec_sets_invariant_p (m->set_dest, | |
1566 | m->consec + 1, | |
1567 | m->insn)))) | |
1568 | && (! m->forces || m->forces->done)) | |
1569 | { | |
1570 | register int regno; | |
1571 | register rtx p; | |
1572 | int savings = m->savings; | |
1573 | ||
1574 | /* We have an insn that is safe to move. | |
1575 | Compute its desirability. */ | |
1576 | ||
1577 | p = m->insn; | |
1578 | regno = m->regno; | |
1579 | ||
1580 | if (loop_dump_stream) | |
1581 | fprintf (loop_dump_stream, "savings %d ", savings); | |
1582 | ||
1583 | if (moved_once[regno]) | |
1584 | { | |
1585 | insn_count *= 2; | |
1586 | ||
1587 | if (loop_dump_stream) | |
1588 | fprintf (loop_dump_stream, "halved since already moved "); | |
1589 | } | |
1590 | ||
1591 | /* An insn MUST be moved if we already moved something else | |
1592 | which is safe only if this one is moved too: that is, | |
1593 | if already_moved[REGNO] is nonzero. */ | |
1594 | ||
1595 | /* An insn is desirable to move if the new lifetime of the | |
1596 | register is no more than THRESHOLD times the old lifetime. | |
1597 | If it's not desirable, it means the loop is so big | |
1598 | that moving won't speed things up much, | |
1599 | and it is liable to make register usage worse. */ | |
1600 | ||
1601 | /* It is also desirable to move if it can be moved at no | |
1602 | extra cost because something else was already moved. */ | |
1603 | ||
1604 | if (already_moved[regno] | |
1605 | || (threshold * savings * m->lifetime) >= insn_count | |
1606 | || (m->forces && m->forces->done | |
1607 | && n_times_used[m->forces->regno] == 1)) | |
1608 | { | |
1609 | int count; | |
1610 | register struct movable *m1; | |
1611 | rtx first; | |
1612 | ||
1613 | /* Now move the insns that set the reg. */ | |
1614 | ||
1615 | if (m->partial && m->match) | |
1616 | { | |
1617 | rtx newpat, i1; | |
1618 | rtx r1, r2; | |
1619 | /* Find the end of this chain of matching regs. | |
1620 | Thus, we load each reg in the chain from that one reg. | |
1621 | And that reg is loaded with 0 directly, | |
1622 | since it has ->match == 0. */ | |
1623 | for (m1 = m; m1->match; m1 = m1->match); | |
1624 | newpat = gen_move_insn (SET_DEST (PATTERN (m->insn)), | |
1625 | SET_DEST (PATTERN (m1->insn))); | |
1626 | i1 = emit_insn_before (newpat, loop_start); | |
1627 | ||
1628 | /* Mark the moved, invariant reg as being allowed to | |
1629 | share a hard reg with the other matching invariant. */ | |
1630 | REG_NOTES (i1) = REG_NOTES (m->insn); | |
1631 | r1 = SET_DEST (PATTERN (m->insn)); | |
1632 | r2 = SET_DEST (PATTERN (m1->insn)); | |
1633 | regs_may_share = gen_rtx (EXPR_LIST, VOIDmode, r1, | |
1634 | gen_rtx (EXPR_LIST, VOIDmode, r2, | |
1635 | regs_may_share)); | |
1636 | delete_insn (m->insn); | |
1637 | ||
1638 | if (new_start == 0) | |
1639 | new_start = i1; | |
1640 | ||
1641 | if (loop_dump_stream) | |
1642 | fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1)); | |
1643 | } | |
1644 | /* If we are to re-generate the item being moved with a | |
1645 | new move insn, first delete what we have and then emit | |
1646 | the move insn before the loop. */ | |
1647 | else if (m->move_insn) | |
1648 | { | |
1649 | rtx i1, temp; | |
1650 | ||
1651 | for (count = m->consec; count >= 0; count--) | |
1652 | { | |
1653 | /* If this is the first insn of a library call sequence, | |
1654 | skip to the end. */ | |
1655 | if (GET_CODE (p) != NOTE | |
1656 | && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
1657 | p = XEXP (temp, 0); | |
1658 | ||
1659 | /* If this is the last insn of a libcall sequence, then | |
1660 | delete every insn in the sequence except the last. | |
1661 | The last insn is handled in the normal manner. */ | |
1662 | if (GET_CODE (p) != NOTE | |
1663 | && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX))) | |
1664 | { | |
1665 | temp = XEXP (temp, 0); | |
1666 | while (temp != p) | |
1667 | temp = delete_insn (temp); | |
1668 | } | |
1669 | ||
1670 | p = delete_insn (p); | |
1671 | } | |
1672 | ||
1673 | start_sequence (); | |
1674 | emit_move_insn (m->set_dest, m->set_src); | |
1675 | temp = get_insns (); | |
1676 | end_sequence (); | |
1677 | ||
1678 | add_label_notes (m->set_src, temp); | |
1679 | ||
1680 | i1 = emit_insns_before (temp, loop_start); | |
1681 | if (! find_reg_note (i1, REG_EQUAL, NULL_RTX)) | |
1682 | REG_NOTES (i1) | |
1683 | = gen_rtx (EXPR_LIST, | |
1684 | m->is_equiv ? REG_EQUIV : REG_EQUAL, | |
1685 | m->set_src, REG_NOTES (i1)); | |
1686 | ||
1687 | if (loop_dump_stream) | |
1688 | fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1)); | |
1689 | ||
1690 | /* The more regs we move, the less we like moving them. */ | |
1691 | threshold -= 3; | |
1692 | } | |
1693 | else | |
1694 | { | |
1695 | for (count = m->consec; count >= 0; count--) | |
1696 | { | |
1697 | rtx i1, temp; | |
1698 | ||
1699 | /* If first insn of libcall sequence, skip to end. */ | |
1700 | /* Do this at start of loop, since p is guaranteed to | |
1701 | be an insn here. */ | |
1702 | if (GET_CODE (p) != NOTE | |
1703 | && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
1704 | p = XEXP (temp, 0); | |
1705 | ||
1706 | /* If last insn of libcall sequence, move all | |
1707 | insns except the last before the loop. The last | |
1708 | insn is handled in the normal manner. */ | |
1709 | if (GET_CODE (p) != NOTE | |
1710 | && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX))) | |
1711 | { | |
1712 | rtx fn_address = 0; | |
1713 | rtx fn_reg = 0; | |
1714 | rtx fn_address_insn = 0; | |
1715 | ||
1716 | first = 0; | |
1717 | for (temp = XEXP (temp, 0); temp != p; | |
1718 | temp = NEXT_INSN (temp)) | |
1719 | { | |
1720 | rtx body; | |
1721 | rtx n; | |
1722 | rtx next; | |
1723 | ||
1724 | if (GET_CODE (temp) == NOTE) | |
1725 | continue; | |
1726 | ||
1727 | body = PATTERN (temp); | |
1728 | ||
1729 | /* Find the next insn after TEMP, | |
1730 | not counting USE or NOTE insns. */ | |
1731 | for (next = NEXT_INSN (temp); next != p; | |
1732 | next = NEXT_INSN (next)) | |
1733 | if (! (GET_CODE (next) == INSN | |
1734 | && GET_CODE (PATTERN (next)) == USE) | |
1735 | && GET_CODE (next) != NOTE) | |
1736 | break; | |
1737 | ||
1738 | /* If that is the call, this may be the insn | |
1739 | that loads the function address. | |
1740 | ||
1741 | Extract the function address from the insn | |
1742 | that loads it into a register. | |
1743 | If this insn was cse'd, we get incorrect code. | |
1744 | ||
1745 | So emit a new move insn that copies the | |
1746 | function address into the register that the | |
1747 | call insn will use. flow.c will delete any | |
1748 | redundant stores that we have created. */ | |
1749 | if (GET_CODE (next) == CALL_INSN | |
1750 | && GET_CODE (body) == SET | |
1751 | && GET_CODE (SET_DEST (body)) == REG | |
1752 | && (n = find_reg_note (temp, REG_EQUAL, | |
1753 | NULL_RTX))) | |
1754 | { | |
1755 | fn_reg = SET_SRC (body); | |
1756 | if (GET_CODE (fn_reg) != REG) | |
1757 | fn_reg = SET_DEST (body); | |
1758 | fn_address = XEXP (n, 0); | |
1759 | fn_address_insn = temp; | |
1760 | } | |
1761 | /* We have the call insn. | |
1762 | If it uses the register we suspect it might, | |
1763 | load it with the correct address directly. */ | |
1764 | if (GET_CODE (temp) == CALL_INSN | |
1765 | && fn_address != 0 | |
1766 | && reg_referenced_p (fn_reg, body)) | |
1767 | emit_insn_after (gen_move_insn (fn_reg, | |
1768 | fn_address), | |
1769 | fn_address_insn); | |
1770 | ||
1771 | if (GET_CODE (temp) == CALL_INSN) | |
1772 | i1 = emit_call_insn_before (body, loop_start); | |
1773 | else | |
1774 | i1 = emit_insn_before (body, loop_start); | |
1775 | if (first == 0) | |
1776 | first = i1; | |
1777 | if (temp == fn_address_insn) | |
1778 | fn_address_insn = i1; | |
1779 | REG_NOTES (i1) = REG_NOTES (temp); | |
1780 | delete_insn (temp); | |
1781 | } | |
1782 | } | |
1783 | if (m->savemode != VOIDmode) | |
1784 | { | |
1785 | /* P sets REG to zero; but we should clear only | |
1786 | the bits that are not covered by the mode | |
1787 | m->savemode. */ | |
1788 | rtx reg = m->set_dest; | |
1789 | rtx sequence; | |
1790 | rtx tem; | |
1791 | ||
1792 | start_sequence (); | |
1793 | tem = expand_binop | |
1794 | (GET_MODE (reg), and_optab, reg, | |
1795 | GEN_INT ((((HOST_WIDE_INT) 1 | |
1796 | << GET_MODE_BITSIZE (m->savemode))) | |
1797 | - 1), | |
1798 | reg, 1, OPTAB_LIB_WIDEN); | |
1799 | if (tem == 0) | |
1800 | abort (); | |
1801 | if (tem != reg) | |
1802 | emit_move_insn (reg, tem); | |
1803 | sequence = gen_sequence (); | |
1804 | end_sequence (); | |
1805 | i1 = emit_insn_before (sequence, loop_start); | |
1806 | } | |
1807 | else if (GET_CODE (p) == CALL_INSN) | |
1808 | i1 = emit_call_insn_before (PATTERN (p), loop_start); | |
1809 | else | |
1810 | i1 = emit_insn_before (PATTERN (p), loop_start); | |
1811 | ||
1812 | REG_NOTES (i1) = REG_NOTES (p); | |
1813 | ||
1814 | if (new_start == 0) | |
1815 | new_start = i1; | |
1816 | ||
1817 | if (loop_dump_stream) | |
1818 | fprintf (loop_dump_stream, " moved to %d", | |
1819 | INSN_UID (i1)); | |
1820 | ||
1821 | #if 0 | |
1822 | /* This isn't needed because REG_NOTES is copied | |
1823 | below and is wrong since P might be a PARALLEL. */ | |
1824 | if (REG_NOTES (i1) == 0 | |
1825 | && ! m->partial /* But not if it's a zero-extend clr. */ | |
1826 | && ! m->global /* and not if used outside the loop | |
1827 | (since it might get set outside). */ | |
1828 | && CONSTANT_P (SET_SRC (PATTERN (p)))) | |
1829 | REG_NOTES (i1) | |
1830 | = gen_rtx (EXPR_LIST, REG_EQUAL, | |
1831 | SET_SRC (PATTERN (p)), REG_NOTES (i1)); | |
1832 | #endif | |
1833 | ||
1834 | /* If library call, now fix the REG_NOTES that contain | |
1835 | insn pointers, namely REG_LIBCALL on FIRST | |
1836 | and REG_RETVAL on I1. */ | |
1837 | if (temp = find_reg_note (i1, REG_RETVAL, NULL_RTX)) | |
1838 | { | |
1839 | XEXP (temp, 0) = first; | |
1840 | temp = find_reg_note (first, REG_LIBCALL, NULL_RTX); | |
1841 | XEXP (temp, 0) = i1; | |
1842 | } | |
1843 | ||
1844 | delete_insn (p); | |
1845 | do p = NEXT_INSN (p); | |
1846 | while (p && GET_CODE (p) == NOTE); | |
1847 | } | |
1848 | ||
1849 | /* The more regs we move, the less we like moving them. */ | |
1850 | threshold -= 3; | |
1851 | } | |
1852 | ||
1853 | /* Any other movable that loads the same register | |
1854 | MUST be moved. */ | |
1855 | already_moved[regno] = 1; | |
1856 | ||
1857 | /* This reg has been moved out of one loop. */ | |
1858 | moved_once[regno] = 1; | |
1859 | ||
1860 | /* The reg set here is now invariant. */ | |
1861 | if (! m->partial) | |
1862 | n_times_set[regno] = 0; | |
1863 | ||
1864 | m->done = 1; | |
1865 | ||
1866 | /* Change the length-of-life info for the register | |
1867 | to say it lives at least the full length of this loop. | |
1868 | This will help guide optimizations in outer loops. */ | |
1869 | ||
1870 | if (uid_luid[regno_first_uid[regno]] > INSN_LUID (loop_start)) | |
1871 | /* This is the old insn before all the moved insns. | |
1872 | We can't use the moved insn because it is out of range | |
1873 | in uid_luid. Only the old insns have luids. */ | |
1874 | regno_first_uid[regno] = INSN_UID (loop_start); | |
1875 | if (uid_luid[regno_last_uid[regno]] < INSN_LUID (end)) | |
1876 | regno_last_uid[regno] = INSN_UID (end); | |
1877 | ||
1878 | /* Combine with this moved insn any other matching movables. */ | |
1879 | ||
1880 | if (! m->partial) | |
1881 | for (m1 = movables; m1; m1 = m1->next) | |
1882 | if (m1->match == m) | |
1883 | { | |
1884 | rtx temp; | |
1885 | ||
1886 | /* Schedule the reg loaded by M1 | |
1887 | for replacement so that shares the reg of M. | |
1888 | If the modes differ (only possible in restricted | |
1889 | circumstances, make a SUBREG. */ | |
1890 | if (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest)) | |
1891 | reg_map[m1->regno] = m->set_dest; | |
1892 | else | |
1893 | reg_map[m1->regno] | |
1894 | = gen_lowpart_common (GET_MODE (m1->set_dest), | |
1895 | m->set_dest); | |
1896 | ||
1897 | /* Get rid of the matching insn | |
1898 | and prevent further processing of it. */ | |
1899 | m1->done = 1; | |
1900 | ||
1901 | /* if library call, delete all insn except last, which | |
1902 | is deleted below */ | |
1903 | if (temp = find_reg_note (m1->insn, REG_RETVAL, | |
1904 | NULL_RTX)) | |
1905 | { | |
1906 | for (temp = XEXP (temp, 0); temp != m1->insn; | |
1907 | temp = NEXT_INSN (temp)) | |
1908 | delete_insn (temp); | |
1909 | } | |
1910 | delete_insn (m1->insn); | |
1911 | ||
1912 | /* Any other movable that loads the same register | |
1913 | MUST be moved. */ | |
1914 | already_moved[m1->regno] = 1; | |
1915 | ||
1916 | /* The reg merged here is now invariant, | |
1917 | if the reg it matches is invariant. */ | |
1918 | if (! m->partial) | |
1919 | n_times_set[m1->regno] = 0; | |
1920 | } | |
1921 | } | |
1922 | else if (loop_dump_stream) | |
1923 | fprintf (loop_dump_stream, "not desirable"); | |
1924 | } | |
1925 | else if (loop_dump_stream && !m->match) | |
1926 | fprintf (loop_dump_stream, "not safe"); | |
1927 | ||
1928 | if (loop_dump_stream) | |
1929 | fprintf (loop_dump_stream, "\n"); | |
1930 | } | |
1931 | ||
1932 | if (new_start == 0) | |
1933 | new_start = loop_start; | |
1934 | ||
1935 | /* Go through all the instructions in the loop, making | |
1936 | all the register substitutions scheduled in REG_MAP. */ | |
1937 | for (p = new_start; p != end; p = NEXT_INSN (p)) | |
1938 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
1939 | || GET_CODE (p) == CALL_INSN) | |
1940 | { | |
1941 | replace_regs (PATTERN (p), reg_map, nregs, 0); | |
1942 | replace_regs (REG_NOTES (p), reg_map, nregs, 0); | |
1943 | } | |
1944 | } | |
1945 | \f | |
1946 | #if 0 | |
1947 | /* Scan X and replace the address of any MEM in it with ADDR. | |
1948 | REG is the address that MEM should have before the replacement. */ | |
1949 | ||
1950 | static void | |
1951 | replace_call_address (x, reg, addr) | |
1952 | rtx x, reg, addr; | |
1953 | { | |
1954 | register enum rtx_code code; | |
1955 | register int i; | |
1956 | register char *fmt; | |
1957 | ||
1958 | if (x == 0) | |
1959 | return; | |
1960 | code = GET_CODE (x); | |
1961 | switch (code) | |
1962 | { | |
1963 | case PC: | |
1964 | case CC0: | |
1965 | case CONST_INT: | |
1966 | case CONST_DOUBLE: | |
1967 | case CONST: | |
1968 | case SYMBOL_REF: | |
1969 | case LABEL_REF: | |
1970 | case REG: | |
1971 | return; | |
1972 | ||
1973 | case SET: | |
1974 | /* Short cut for very common case. */ | |
1975 | replace_call_address (XEXP (x, 1), reg, addr); | |
1976 | return; | |
1977 | ||
1978 | case CALL: | |
1979 | /* Short cut for very common case. */ | |
1980 | replace_call_address (XEXP (x, 0), reg, addr); | |
1981 | return; | |
1982 | ||
1983 | case MEM: | |
1984 | /* If this MEM uses a reg other than the one we expected, | |
1985 | something is wrong. */ | |
1986 | if (XEXP (x, 0) != reg) | |
1987 | abort (); | |
1988 | XEXP (x, 0) = addr; | |
1989 | return; | |
1990 | } | |
1991 | ||
1992 | fmt = GET_RTX_FORMAT (code); | |
1993 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1994 | { | |
1995 | if (fmt[i] == 'e') | |
1996 | replace_call_address (XEXP (x, i), reg, addr); | |
1997 | if (fmt[i] == 'E') | |
1998 | { | |
1999 | register int j; | |
2000 | for (j = 0; j < XVECLEN (x, i); j++) | |
2001 | replace_call_address (XVECEXP (x, i, j), reg, addr); | |
2002 | } | |
2003 | } | |
2004 | } | |
2005 | #endif | |
2006 | \f | |
2007 | /* Return the number of memory refs to addresses that vary | |
2008 | in the rtx X. */ | |
2009 | ||
2010 | static int | |
2011 | count_nonfixed_reads (x) | |
2012 | rtx x; | |
2013 | { | |
2014 | register enum rtx_code code; | |
2015 | register int i; | |
2016 | register char *fmt; | |
2017 | int value; | |
2018 | ||
2019 | if (x == 0) | |
2020 | return 0; | |
2021 | ||
2022 | code = GET_CODE (x); | |
2023 | switch (code) | |
2024 | { | |
2025 | case PC: | |
2026 | case CC0: | |
2027 | case CONST_INT: | |
2028 | case CONST_DOUBLE: | |
2029 | case CONST: | |
2030 | case SYMBOL_REF: | |
2031 | case LABEL_REF: | |
2032 | case REG: | |
2033 | return 0; | |
2034 | ||
2035 | case MEM: | |
2036 | return ((invariant_p (XEXP (x, 0)) != 1) | |
2037 | + count_nonfixed_reads (XEXP (x, 0))); | |
2038 | } | |
2039 | ||
2040 | value = 0; | |
2041 | fmt = GET_RTX_FORMAT (code); | |
2042 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2043 | { | |
2044 | if (fmt[i] == 'e') | |
2045 | value += count_nonfixed_reads (XEXP (x, i)); | |
2046 | if (fmt[i] == 'E') | |
2047 | { | |
2048 | register int j; | |
2049 | for (j = 0; j < XVECLEN (x, i); j++) | |
2050 | value += count_nonfixed_reads (XVECEXP (x, i, j)); | |
2051 | } | |
2052 | } | |
2053 | return value; | |
2054 | } | |
2055 | ||
2056 | \f | |
2057 | #if 0 | |
2058 | /* P is an instruction that sets a register to the result of a ZERO_EXTEND. | |
2059 | Replace it with an instruction to load just the low bytes | |
2060 | if the machine supports such an instruction, | |
2061 | and insert above LOOP_START an instruction to clear the register. */ | |
2062 | ||
2063 | static void | |
2064 | constant_high_bytes (p, loop_start) | |
2065 | rtx p, loop_start; | |
2066 | { | |
2067 | register rtx new; | |
2068 | register int insn_code_number; | |
2069 | ||
2070 | /* Try to change (SET (REG ...) (ZERO_EXTEND (..:B ...))) | |
2071 | to (SET (STRICT_LOW_PART (SUBREG:B (REG...))) ...). */ | |
2072 | ||
2073 | new = gen_rtx (SET, VOIDmode, | |
2074 | gen_rtx (STRICT_LOW_PART, VOIDmode, | |
2075 | gen_rtx (SUBREG, GET_MODE (XEXP (SET_SRC (PATTERN (p)), 0)), | |
2076 | SET_DEST (PATTERN (p)), | |
2077 | 0)), | |
2078 | XEXP (SET_SRC (PATTERN (p)), 0)); | |
2079 | insn_code_number = recog (new, p); | |
2080 | ||
2081 | if (insn_code_number) | |
2082 | { | |
2083 | register int i; | |
2084 | ||
2085 | /* Clear destination register before the loop. */ | |
2086 | emit_insn_before (gen_rtx (SET, VOIDmode, | |
2087 | SET_DEST (PATTERN (p)), | |
2088 | const0_rtx), | |
2089 | loop_start); | |
2090 | ||
2091 | /* Inside the loop, just load the low part. */ | |
2092 | PATTERN (p) = new; | |
2093 | } | |
2094 | } | |
2095 | #endif | |
2096 | \f | |
2097 | /* Scan a loop setting the variables `unknown_address_altered', | |
2098 | `num_mem_sets', `loop_continue', loops_enclosed', `loop_has_call', | |
2099 | and `loop_has_volatile'. | |
2100 | Also, fill in the array `loop_store_mems'. */ | |
2101 | ||
2102 | static void | |
2103 | prescan_loop (start, end) | |
2104 | rtx start, end; | |
2105 | { | |
2106 | register int level = 1; | |
2107 | register rtx insn; | |
2108 | ||
2109 | unknown_address_altered = 0; | |
2110 | loop_has_call = 0; | |
2111 | loop_has_volatile = 0; | |
2112 | loop_store_mems_idx = 0; | |
2113 | ||
2114 | num_mem_sets = 0; | |
2115 | loops_enclosed = 1; | |
2116 | loop_continue = 0; | |
2117 | ||
2118 | for (insn = NEXT_INSN (start); insn != NEXT_INSN (end); | |
2119 | insn = NEXT_INSN (insn)) | |
2120 | { | |
2121 | if (GET_CODE (insn) == NOTE) | |
2122 | { | |
2123 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
2124 | { | |
2125 | ++level; | |
2126 | /* Count number of loops contained in this one. */ | |
2127 | loops_enclosed++; | |
2128 | } | |
2129 | else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) | |
2130 | { | |
2131 | --level; | |
2132 | if (level == 0) | |
2133 | { | |
2134 | end = insn; | |
2135 | break; | |
2136 | } | |
2137 | } | |
2138 | else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT) | |
2139 | { | |
2140 | if (level == 1) | |
2141 | loop_continue = insn; | |
2142 | } | |
2143 | } | |
2144 | else if (GET_CODE (insn) == CALL_INSN) | |
2145 | { | |
2146 | unknown_address_altered = 1; | |
2147 | loop_has_call = 1; | |
2148 | } | |
2149 | else | |
2150 | { | |
2151 | if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN) | |
2152 | { | |
2153 | if (volatile_refs_p (PATTERN (insn))) | |
2154 | loop_has_volatile = 1; | |
2155 | ||
2156 | note_stores (PATTERN (insn), note_addr_stored); | |
2157 | } | |
2158 | } | |
2159 | } | |
2160 | } | |
2161 | \f | |
2162 | /* Scan the function looking for loops. Record the start and end of each loop. | |
2163 | Also mark as invalid loops any loops that contain a setjmp or are branched | |
2164 | to from outside the loop. */ | |
2165 | ||
2166 | static void | |
2167 | find_and_verify_loops (f) | |
2168 | rtx f; | |
2169 | { | |
2170 | rtx insn; | |
2171 | int current_loop = -1; | |
2172 | int next_loop = -1; | |
2173 | int loop; | |
2174 | ||
2175 | /* If there are jumps to undefined labels, | |
2176 | treat them as jumps out of any/all loops. | |
2177 | This also avoids writing past end of tables when there are no loops. */ | |
2178 | uid_loop_num[0] = -1; | |
2179 | ||
2180 | /* Find boundaries of loops, mark which loops are contained within | |
2181 | loops, and invalidate loops that have setjmp. */ | |
2182 | ||
2183 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
2184 | { | |
2185 | if (GET_CODE (insn) == NOTE) | |
2186 | switch (NOTE_LINE_NUMBER (insn)) | |
2187 | { | |
2188 | case NOTE_INSN_LOOP_BEG: | |
2189 | loop_number_loop_starts[++next_loop] = insn; | |
2190 | loop_number_loop_ends[next_loop] = 0; | |
2191 | loop_outer_loop[next_loop] = current_loop; | |
2192 | loop_invalid[next_loop] = 0; | |
2193 | loop_number_exit_labels[next_loop] = 0; | |
2194 | current_loop = next_loop; | |
2195 | break; | |
2196 | ||
2197 | case NOTE_INSN_SETJMP: | |
2198 | /* In this case, we must invalidate our current loop and any | |
2199 | enclosing loop. */ | |
2200 | for (loop = current_loop; loop != -1; loop = loop_outer_loop[loop]) | |
2201 | { | |
2202 | loop_invalid[loop] = 1; | |
2203 | if (loop_dump_stream) | |
2204 | fprintf (loop_dump_stream, | |
2205 | "\nLoop at %d ignored due to setjmp.\n", | |
2206 | INSN_UID (loop_number_loop_starts[loop])); | |
2207 | } | |
2208 | break; | |
2209 | ||
2210 | case NOTE_INSN_LOOP_END: | |
2211 | if (current_loop == -1) | |
2212 | abort (); | |
2213 | ||
2214 | loop_number_loop_ends[current_loop] = insn; | |
2215 | current_loop = loop_outer_loop[current_loop]; | |
2216 | break; | |
2217 | ||
2218 | } | |
2219 | ||
2220 | /* Note that this will mark the NOTE_INSN_LOOP_END note as being in the | |
2221 | enclosing loop, but this doesn't matter. */ | |
2222 | uid_loop_num[INSN_UID (insn)] = current_loop; | |
2223 | } | |
2224 | ||
2225 | /* Now scan all JUMP_INSN's in the function. If any branches into a loop | |
2226 | that it is not contained within, that loop is marked invalid. | |
2227 | ||
2228 | Also look for blocks of code ending in an unconditional branch that | |
2229 | exits the loop. If such a block is surrounded by a conditional | |
2230 | branch around the block, move the block elsewhere (see below) and | |
2231 | invert the jump to point to the code block. This may eliminate a | |
2232 | label in our loop and will simplify processing by both us and a | |
2233 | possible second cse pass. */ | |
2234 | ||
2235 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
2236 | if (GET_CODE (insn) == JUMP_INSN) | |
2237 | { | |
2238 | int this_loop_num = uid_loop_num[INSN_UID (insn)]; | |
2239 | ||
2240 | mark_loop_jump (PATTERN (insn), this_loop_num); | |
2241 | ||
2242 | /* See if this is an unconditional branch outside the loop. */ | |
2243 | if (this_loop_num != -1 | |
2244 | && (GET_CODE (PATTERN (insn)) == RETURN | |
2245 | || (simplejump_p (insn) | |
2246 | && (uid_loop_num[INSN_UID (JUMP_LABEL (insn))] | |
2247 | != this_loop_num))) | |
2248 | && get_max_uid () < max_uid_for_loop) | |
2249 | { | |
2250 | rtx p; | |
2251 | rtx our_next = next_real_insn (insn); | |
2252 | ||
2253 | /* Go backwards until we reach the start of the loop, a label, | |
2254 | or a JUMP_INSN. */ | |
2255 | for (p = PREV_INSN (insn); | |
2256 | GET_CODE (p) != CODE_LABEL | |
2257 | && ! (GET_CODE (p) == NOTE | |
2258 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG) | |
2259 | && GET_CODE (p) != JUMP_INSN; | |
2260 | p = PREV_INSN (p)) | |
2261 | ; | |
2262 | ||
2263 | /* If we stopped on a JUMP_INSN to the next insn after INSN, | |
2264 | we have a block of code to try to move. | |
2265 | ||
2266 | We look backward and then forward from the target of INSN | |
2267 | to find a BARRIER at the same loop depth as the target. | |
2268 | If we find such a BARRIER, we make a new label for the start | |
2269 | of the block, invert the jump in P and point it to that label, | |
2270 | and move the block of code to the spot we found. */ | |
2271 | ||
2272 | if (GET_CODE (p) == JUMP_INSN | |
2273 | && JUMP_LABEL (p) != 0 | |
2274 | /* Just ignore jumps to labels that were never emitted. | |
2275 | These always indicate compilation errors. */ | |
2276 | && INSN_UID (JUMP_LABEL (p)) != 0 | |
2277 | && condjump_p (p) | |
2278 | && ! simplejump_p (p) | |
2279 | && next_real_insn (JUMP_LABEL (p)) == our_next) | |
2280 | { | |
2281 | rtx target | |
2282 | = JUMP_LABEL (insn) ? JUMP_LABEL (insn) : get_last_insn (); | |
2283 | int target_loop_num = uid_loop_num[INSN_UID (target)]; | |
2284 | rtx loc; | |
2285 | ||
2286 | for (loc = target; loc; loc = PREV_INSN (loc)) | |
2287 | if (GET_CODE (loc) == BARRIER | |
2288 | && uid_loop_num[INSN_UID (loc)] == target_loop_num) | |
2289 | break; | |
2290 | ||
2291 | if (loc == 0) | |
2292 | for (loc = target; loc; loc = NEXT_INSN (loc)) | |
2293 | if (GET_CODE (loc) == BARRIER | |
2294 | && uid_loop_num[INSN_UID (loc)] == target_loop_num) | |
2295 | break; | |
2296 | ||
2297 | if (loc) | |
2298 | { | |
2299 | rtx cond_label = JUMP_LABEL (p); | |
2300 | rtx new_label = get_label_after (p); | |
2301 | ||
2302 | /* Ensure our label doesn't go away. */ | |
2303 | LABEL_NUSES (cond_label)++; | |
2304 | ||
2305 | /* Verify that uid_loop_num is large enough and that | |
2306 | we can invert P. */ | |
2307 | if (invert_jump (p, new_label)) | |
2308 | { | |
2309 | rtx q, r; | |
2310 | ||
2311 | /* Include the BARRIER after INSN and copy the | |
2312 | block after LOC. */ | |
2313 | new_label = squeeze_notes (new_label, NEXT_INSN (insn)); | |
2314 | reorder_insns (new_label, NEXT_INSN (insn), loc); | |
2315 | ||
2316 | /* All those insns are now in TARGET_LOOP_NUM. */ | |
2317 | for (q = new_label; q != NEXT_INSN (NEXT_INSN (insn)); | |
2318 | q = NEXT_INSN (q)) | |
2319 | uid_loop_num[INSN_UID (q)] = target_loop_num; | |
2320 | ||
2321 | /* The label jumped to by INSN is no longer a loop exit. | |
2322 | Unless INSN does not have a label (e.g., it is a | |
2323 | RETURN insn), search loop_number_exit_labels to find | |
2324 | its label_ref, and remove it. Also turn off | |
2325 | LABEL_OUTSIDE_LOOP_P bit. */ | |
2326 | if (JUMP_LABEL (insn)) | |
2327 | { | |
2328 | for (q = 0, | |
2329 | r = loop_number_exit_labels[this_loop_num]; | |
2330 | r; q = r, r = LABEL_NEXTREF (r)) | |
2331 | if (XEXP (r, 0) == JUMP_LABEL (insn)) | |
2332 | { | |
2333 | LABEL_OUTSIDE_LOOP_P (r) = 0; | |
2334 | if (q) | |
2335 | LABEL_NEXTREF (q) = LABEL_NEXTREF (r); | |
2336 | else | |
2337 | loop_number_exit_labels[this_loop_num] | |
2338 | = LABEL_NEXTREF (r); | |
2339 | break; | |
2340 | } | |
2341 | ||
2342 | /* If we didn't find it, then something is wrong. */ | |
2343 | if (! r) | |
2344 | abort (); | |
2345 | } | |
2346 | ||
2347 | /* P is now a jump outside the loop, so it must be put | |
2348 | in loop_number_exit_labels, and marked as such. | |
2349 | The easiest way to do this is to just call | |
2350 | mark_loop_jump again for P. */ | |
2351 | mark_loop_jump (PATTERN (p), this_loop_num); | |
2352 | ||
2353 | /* If INSN now jumps to the insn after it, | |
2354 | delete INSN. */ | |
2355 | if (JUMP_LABEL (insn) != 0 | |
2356 | && (next_real_insn (JUMP_LABEL (insn)) | |
2357 | == next_real_insn (insn))) | |
2358 | delete_insn (insn); | |
2359 | } | |
2360 | ||
2361 | /* Continue the loop after where the conditional | |
2362 | branch used to jump, since the only branch insn | |
2363 | in the block (if it still remains) is an inter-loop | |
2364 | branch and hence needs no processing. */ | |
2365 | insn = NEXT_INSN (cond_label); | |
2366 | ||
2367 | if (--LABEL_NUSES (cond_label) == 0) | |
2368 | delete_insn (cond_label); | |
2369 | } | |
2370 | } | |
2371 | } | |
2372 | } | |
2373 | } | |
2374 | ||
2375 | /* If any label in X jumps to a loop different from LOOP_NUM and any of the | |
2376 | loops it is contained in, mark the target loop invalid. | |
2377 | ||
2378 | For speed, we assume that X is part of a pattern of a JUMP_INSN. */ | |
2379 | ||
2380 | static void | |
2381 | mark_loop_jump (x, loop_num) | |
2382 | rtx x; | |
2383 | int loop_num; | |
2384 | { | |
2385 | int dest_loop; | |
2386 | int outer_loop; | |
2387 | int i; | |
2388 | ||
2389 | switch (GET_CODE (x)) | |
2390 | { | |
2391 | case PC: | |
2392 | case USE: | |
2393 | case CLOBBER: | |
2394 | case REG: | |
2395 | case MEM: | |
2396 | case CONST_INT: | |
2397 | case CONST_DOUBLE: | |
2398 | case RETURN: | |
2399 | return; | |
2400 | ||
2401 | case CONST: | |
2402 | /* There could be a label reference in here. */ | |
2403 | mark_loop_jump (XEXP (x, 0), loop_num); | |
2404 | return; | |
2405 | ||
2406 | case PLUS: | |
2407 | case MINUS: | |
2408 | case MULT: | |
2409 | case LSHIFT: | |
2410 | mark_loop_jump (XEXP (x, 0), loop_num); | |
2411 | mark_loop_jump (XEXP (x, 1), loop_num); | |
2412 | return; | |
2413 | ||
2414 | case SIGN_EXTEND: | |
2415 | case ZERO_EXTEND: | |
2416 | mark_loop_jump (XEXP (x, 0), loop_num); | |
2417 | return; | |
2418 | ||
2419 | case LABEL_REF: | |
2420 | dest_loop = uid_loop_num[INSN_UID (XEXP (x, 0))]; | |
2421 | ||
2422 | /* Link together all labels that branch outside the loop. This | |
2423 | is used by final_[bg]iv_value and the loop unrolling code. Also | |
2424 | mark this LABEL_REF so we know that this branch should predict | |
2425 | false. */ | |
2426 | ||
2427 | if (dest_loop != loop_num && loop_num != -1) | |
2428 | { | |
2429 | LABEL_OUTSIDE_LOOP_P (x) = 1; | |
2430 | LABEL_NEXTREF (x) = loop_number_exit_labels[loop_num]; | |
2431 | loop_number_exit_labels[loop_num] = x; | |
2432 | } | |
2433 | ||
2434 | /* If this is inside a loop, but not in the current loop or one enclosed | |
2435 | by it, it invalidates at least one loop. */ | |
2436 | ||
2437 | if (dest_loop == -1) | |
2438 | return; | |
2439 | ||
2440 | /* We must invalidate every nested loop containing the target of this | |
2441 | label, except those that also contain the jump insn. */ | |
2442 | ||
2443 | for (; dest_loop != -1; dest_loop = loop_outer_loop[dest_loop]) | |
2444 | { | |
2445 | /* Stop when we reach a loop that also contains the jump insn. */ | |
2446 | for (outer_loop = loop_num; outer_loop != -1; | |
2447 | outer_loop = loop_outer_loop[outer_loop]) | |
2448 | if (dest_loop == outer_loop) | |
2449 | return; | |
2450 | ||
2451 | /* If we get here, we know we need to invalidate a loop. */ | |
2452 | if (loop_dump_stream && ! loop_invalid[dest_loop]) | |
2453 | fprintf (loop_dump_stream, | |
2454 | "\nLoop at %d ignored due to multiple entry points.\n", | |
2455 | INSN_UID (loop_number_loop_starts[dest_loop])); | |
2456 | ||
2457 | loop_invalid[dest_loop] = 1; | |
2458 | } | |
2459 | return; | |
2460 | ||
2461 | case SET: | |
2462 | /* If this is not setting pc, ignore. */ | |
2463 | if (SET_DEST (x) == pc_rtx) | |
2464 | mark_loop_jump (SET_SRC (x), loop_num); | |
2465 | return; | |
2466 | ||
2467 | case IF_THEN_ELSE: | |
2468 | mark_loop_jump (XEXP (x, 1), loop_num); | |
2469 | mark_loop_jump (XEXP (x, 2), loop_num); | |
2470 | return; | |
2471 | ||
2472 | case PARALLEL: | |
2473 | case ADDR_VEC: | |
2474 | for (i = 0; i < XVECLEN (x, 0); i++) | |
2475 | mark_loop_jump (XVECEXP (x, 0, i), loop_num); | |
2476 | return; | |
2477 | ||
2478 | case ADDR_DIFF_VEC: | |
2479 | for (i = 0; i < XVECLEN (x, 1); i++) | |
2480 | mark_loop_jump (XVECEXP (x, 1, i), loop_num); | |
2481 | return; | |
2482 | ||
2483 | default: | |
2484 | /* Nothing else should occur in a JUMP_INSN. */ | |
2485 | abort (); | |
2486 | } | |
2487 | } | |
2488 | \f | |
2489 | /* Return nonzero if there is a label in the range from | |
2490 | insn INSN to and including the insn whose luid is END | |
2491 | INSN must have an assigned luid (i.e., it must not have | |
2492 | been previously created by loop.c). */ | |
2493 | ||
2494 | static int | |
2495 | labels_in_range_p (insn, end) | |
2496 | rtx insn; | |
2497 | int end; | |
2498 | { | |
2499 | while (insn && INSN_LUID (insn) <= end) | |
2500 | { | |
2501 | if (GET_CODE (insn) == CODE_LABEL) | |
2502 | return 1; | |
2503 | insn = NEXT_INSN (insn); | |
2504 | } | |
2505 | ||
2506 | return 0; | |
2507 | } | |
2508 | ||
2509 | /* Record that a memory reference X is being set. */ | |
2510 | ||
2511 | static void | |
2512 | note_addr_stored (x) | |
2513 | rtx x; | |
2514 | { | |
2515 | register int i; | |
2516 | ||
2517 | if (x == 0 || GET_CODE (x) != MEM) | |
2518 | return; | |
2519 | ||
2520 | /* Count number of memory writes. | |
2521 | This affects heuristics in strength_reduce. */ | |
2522 | num_mem_sets++; | |
2523 | ||
2524 | if (unknown_address_altered) | |
2525 | return; | |
2526 | ||
2527 | for (i = 0; i < loop_store_mems_idx; i++) | |
2528 | if (rtx_equal_p (XEXP (loop_store_mems[i], 0), XEXP (x, 0)) | |
2529 | && MEM_IN_STRUCT_P (x) == MEM_IN_STRUCT_P (loop_store_mems[i])) | |
2530 | { | |
2531 | /* We are storing at the same address as previously noted. Save the | |
2532 | wider reference, treating BLKmode as wider. */ | |
2533 | if (GET_MODE (x) == BLKmode | |
2534 | || (GET_MODE_SIZE (GET_MODE (x)) | |
2535 | > GET_MODE_SIZE (GET_MODE (loop_store_mems[i])))) | |
2536 | loop_store_mems[i] = x; | |
2537 | break; | |
2538 | } | |
2539 | ||
2540 | if (i == NUM_STORES) | |
2541 | unknown_address_altered = 1; | |
2542 | ||
2543 | else if (i == loop_store_mems_idx) | |
2544 | loop_store_mems[loop_store_mems_idx++] = x; | |
2545 | } | |
2546 | \f | |
2547 | /* Return nonzero if the rtx X is invariant over the current loop. | |
2548 | ||
2549 | The value is 2 if we refer to something only conditionally invariant. | |
2550 | ||
2551 | If `unknown_address_altered' is nonzero, no memory ref is invariant. | |
2552 | Otherwise, a memory ref is invariant if it does not conflict with | |
2553 | anything stored in `loop_store_mems'. */ | |
2554 | ||
2555 | int | |
2556 | invariant_p (x) | |
2557 | register rtx x; | |
2558 | { | |
2559 | register int i; | |
2560 | register enum rtx_code code; | |
2561 | register char *fmt; | |
2562 | int conditional = 0; | |
2563 | ||
2564 | if (x == 0) | |
2565 | return 1; | |
2566 | code = GET_CODE (x); | |
2567 | switch (code) | |
2568 | { | |
2569 | case CONST_INT: | |
2570 | case CONST_DOUBLE: | |
2571 | case SYMBOL_REF: | |
2572 | case CONST: | |
2573 | return 1; | |
2574 | ||
2575 | case LABEL_REF: | |
2576 | /* A LABEL_REF is normally invariant, however, if we are unrolling | |
2577 | loops, and this label is inside the loop, then it isn't invariant. | |
2578 | This is because each unrolled copy of the loop body will have | |
2579 | a copy of this label. If this was invariant, then an insn loading | |
2580 | the address of this label into a register might get moved outside | |
2581 | the loop, and then each loop body would end up using the same label. | |
2582 | ||
2583 | We don't know the loop bounds here though, so just fail for all | |
2584 | labels. */ | |
2585 | if (flag_unroll_loops) | |
2586 | return 0; | |
2587 | else | |
2588 | return 1; | |
2589 | ||
2590 | case PC: | |
2591 | case CC0: | |
2592 | case UNSPEC_VOLATILE: | |
2593 | return 0; | |
2594 | ||
2595 | case REG: | |
2596 | /* We used to check RTX_UNCHANGING_P (x) here, but that is invalid | |
2597 | since the reg might be set by initialization within the loop. */ | |
2598 | if (x == frame_pointer_rtx || x == arg_pointer_rtx) | |
2599 | return 1; | |
2600 | if (loop_has_call | |
2601 | && REGNO (x) < FIRST_PSEUDO_REGISTER && call_used_regs[REGNO (x)]) | |
2602 | return 0; | |
2603 | if (n_times_set[REGNO (x)] < 0) | |
2604 | return 2; | |
2605 | return n_times_set[REGNO (x)] == 0; | |
2606 | ||
2607 | case MEM: | |
2608 | /* Read-only items (such as constants in a constant pool) are | |
2609 | invariant if their address is. */ | |
2610 | if (RTX_UNCHANGING_P (x)) | |
2611 | break; | |
2612 | ||
2613 | /* If we filled the table (or had a subroutine call), any location | |
2614 | in memory could have been clobbered. */ | |
2615 | if (unknown_address_altered | |
2616 | /* Don't mess with volatile memory references. */ | |
2617 | || MEM_VOLATILE_P (x)) | |
2618 | return 0; | |
2619 | ||
2620 | /* See if there is any dependence between a store and this load. */ | |
2621 | for (i = loop_store_mems_idx - 1; i >= 0; i--) | |
2622 | if (true_dependence (loop_store_mems[i], x)) | |
2623 | return 0; | |
2624 | ||
2625 | /* It's not invalidated by a store in memory | |
2626 | but we must still verify the address is invariant. */ | |
2627 | break; | |
2628 | ||
2629 | case ASM_OPERANDS: | |
2630 | /* Don't mess with insns declared volatile. */ | |
2631 | if (MEM_VOLATILE_P (x)) | |
2632 | return 0; | |
2633 | } | |
2634 | ||
2635 | fmt = GET_RTX_FORMAT (code); | |
2636 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2637 | { | |
2638 | if (fmt[i] == 'e') | |
2639 | { | |
2640 | int tem = invariant_p (XEXP (x, i)); | |
2641 | if (tem == 0) | |
2642 | return 0; | |
2643 | if (tem == 2) | |
2644 | conditional = 1; | |
2645 | } | |
2646 | else if (fmt[i] == 'E') | |
2647 | { | |
2648 | register int j; | |
2649 | for (j = 0; j < XVECLEN (x, i); j++) | |
2650 | { | |
2651 | int tem = invariant_p (XVECEXP (x, i, j)); | |
2652 | if (tem == 0) | |
2653 | return 0; | |
2654 | if (tem == 2) | |
2655 | conditional = 1; | |
2656 | } | |
2657 | ||
2658 | } | |
2659 | } | |
2660 | ||
2661 | return 1 + conditional; | |
2662 | } | |
2663 | ||
2664 | /* Return 1 if OTHER (a mem ref) overlaps the area of memory | |
2665 | which is SIZE bytes starting at BASE. */ | |
2666 | ||
2667 | int | |
2668 | addr_overlap_p (other, base, size) | |
2669 | rtx other; | |
2670 | rtx base; | |
2671 | HOST_WIDE_INT size; | |
2672 | { | |
2673 | HOST_WIDE_INT start = 0, end; | |
2674 | ||
2675 | if (GET_CODE (base) == CONST) | |
2676 | base = XEXP (base, 0); | |
2677 | if (GET_CODE (base) == PLUS | |
2678 | && GET_CODE (XEXP (base, 1)) == CONST_INT) | |
2679 | { | |
2680 | start = INTVAL (XEXP (base, 1)); | |
2681 | base = XEXP (base, 0); | |
2682 | } | |
2683 | ||
2684 | end = start + size; | |
2685 | return refers_to_mem_p (other, base, start, end); | |
2686 | } | |
2687 | \f | |
2688 | /* Return nonzero if all the insns in the loop that set REG | |
2689 | are INSN and the immediately following insns, | |
2690 | and if each of those insns sets REG in an invariant way | |
2691 | (not counting uses of REG in them). | |
2692 | ||
2693 | The value is 2 if some of these insns are only conditionally invariant. | |
2694 | ||
2695 | We assume that INSN itself is the first set of REG | |
2696 | and that its source is invariant. */ | |
2697 | ||
2698 | static int | |
2699 | consec_sets_invariant_p (reg, n_sets, insn) | |
2700 | int n_sets; | |
2701 | rtx reg, insn; | |
2702 | { | |
2703 | register rtx p = insn; | |
2704 | register int regno = REGNO (reg); | |
2705 | rtx temp; | |
2706 | /* Number of sets we have to insist on finding after INSN. */ | |
2707 | int count = n_sets - 1; | |
2708 | int old = n_times_set[regno]; | |
2709 | int value = 0; | |
2710 | int this; | |
2711 | ||
2712 | /* If N_SETS hit the limit, we can't rely on its value. */ | |
2713 | if (n_sets == 127) | |
2714 | return 0; | |
2715 | ||
2716 | n_times_set[regno] = 0; | |
2717 | ||
2718 | while (count > 0) | |
2719 | { | |
2720 | register enum rtx_code code; | |
2721 | rtx set; | |
2722 | ||
2723 | p = NEXT_INSN (p); | |
2724 | code = GET_CODE (p); | |
2725 | ||
2726 | /* If library call, skip to end of of it. */ | |
2727 | if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
2728 | p = XEXP (temp, 0); | |
2729 | ||
2730 | this = 0; | |
2731 | if (code == INSN | |
2732 | && (set = single_set (p)) | |
2733 | && GET_CODE (SET_DEST (set)) == REG | |
2734 | && REGNO (SET_DEST (set)) == regno) | |
2735 | { | |
2736 | this = invariant_p (SET_SRC (set)); | |
2737 | if (this != 0) | |
2738 | value |= this; | |
2739 | else if (temp = find_reg_note (p, REG_EQUAL, NULL_RTX)) | |
2740 | { | |
2741 | this = invariant_p (XEXP (temp, 0)); | |
2742 | if (this != 0) | |
2743 | value |= this; | |
2744 | } | |
2745 | } | |
2746 | if (this != 0) | |
2747 | count--; | |
2748 | else if (code != NOTE) | |
2749 | { | |
2750 | n_times_set[regno] = old; | |
2751 | return 0; | |
2752 | } | |
2753 | } | |
2754 | ||
2755 | n_times_set[regno] = old; | |
2756 | /* If invariant_p ever returned 2, we return 2. */ | |
2757 | return 1 + (value & 2); | |
2758 | } | |
2759 | ||
2760 | #if 0 | |
2761 | /* I don't think this condition is sufficient to allow INSN | |
2762 | to be moved, so we no longer test it. */ | |
2763 | ||
2764 | /* Return 1 if all insns in the basic block of INSN and following INSN | |
2765 | that set REG are invariant according to TABLE. */ | |
2766 | ||
2767 | static int | |
2768 | all_sets_invariant_p (reg, insn, table) | |
2769 | rtx reg, insn; | |
2770 | short *table; | |
2771 | { | |
2772 | register rtx p = insn; | |
2773 | register int regno = REGNO (reg); | |
2774 | ||
2775 | while (1) | |
2776 | { | |
2777 | register enum rtx_code code; | |
2778 | p = NEXT_INSN (p); | |
2779 | code = GET_CODE (p); | |
2780 | if (code == CODE_LABEL || code == JUMP_INSN) | |
2781 | return 1; | |
2782 | if (code == INSN && GET_CODE (PATTERN (p)) == SET | |
2783 | && GET_CODE (SET_DEST (PATTERN (p))) == REG | |
2784 | && REGNO (SET_DEST (PATTERN (p))) == regno) | |
2785 | { | |
2786 | if (!invariant_p (SET_SRC (PATTERN (p)), table)) | |
2787 | return 0; | |
2788 | } | |
2789 | } | |
2790 | } | |
2791 | #endif /* 0 */ | |
2792 | \f | |
2793 | /* Look at all uses (not sets) of registers in X. For each, if it is | |
2794 | the single use, set USAGE[REGNO] to INSN; if there was a previous use in | |
2795 | a different insn, set USAGE[REGNO] to const0_rtx. */ | |
2796 | ||
2797 | static void | |
2798 | find_single_use_in_loop (insn, x, usage) | |
2799 | rtx insn; | |
2800 | rtx x; | |
2801 | rtx *usage; | |
2802 | { | |
2803 | enum rtx_code code = GET_CODE (x); | |
2804 | char *fmt = GET_RTX_FORMAT (code); | |
2805 | int i, j; | |
2806 | ||
2807 | if (code == REG) | |
2808 | usage[REGNO (x)] | |
2809 | = (usage[REGNO (x)] != 0 && usage[REGNO (x)] != insn) | |
2810 | ? const0_rtx : insn; | |
2811 | ||
2812 | else if (code == SET) | |
2813 | { | |
2814 | /* Don't count SET_DEST if it is a REG; otherwise count things | |
2815 | in SET_DEST because if a register is partially modified, it won't | |
2816 | show up as a potential movable so we don't care how USAGE is set | |
2817 | for it. */ | |
2818 | if (GET_CODE (SET_DEST (x)) != REG) | |
2819 | find_single_use_in_loop (insn, SET_DEST (x), usage); | |
2820 | find_single_use_in_loop (insn, SET_SRC (x), usage); | |
2821 | } | |
2822 | else | |
2823 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2824 | { | |
2825 | if (fmt[i] == 'e' && XEXP (x, i) != 0) | |
2826 | find_single_use_in_loop (insn, XEXP (x, i), usage); | |
2827 | else if (fmt[i] == 'E') | |
2828 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
2829 | find_single_use_in_loop (insn, XVECEXP (x, i, j), usage); | |
2830 | } | |
2831 | } | |
2832 | \f | |
2833 | /* Increment N_TIMES_SET at the index of each register | |
2834 | that is modified by an insn between FROM and TO. | |
2835 | If the value of an element of N_TIMES_SET becomes 127 or more, | |
2836 | stop incrementing it, to avoid overflow. | |
2837 | ||
2838 | Store in SINGLE_USAGE[I] the single insn in which register I is | |
2839 | used, if it is only used once. Otherwise, it is set to 0 (for no | |
2840 | uses) or const0_rtx for more than one use. This parameter may be zero, | |
2841 | in which case this processing is not done. | |
2842 | ||
2843 | Store in *COUNT_PTR the number of actual instruction | |
2844 | in the loop. We use this to decide what is worth moving out. */ | |
2845 | ||
2846 | /* last_set[n] is nonzero iff reg n has been set in the current basic block. | |
2847 | In that case, it is the insn that last set reg n. */ | |
2848 | ||
2849 | static void | |
2850 | count_loop_regs_set (from, to, may_not_move, single_usage, count_ptr, nregs) | |
2851 | register rtx from, to; | |
2852 | char *may_not_move; | |
2853 | rtx *single_usage; | |
2854 | int *count_ptr; | |
2855 | int nregs; | |
2856 | { | |
2857 | register rtx *last_set = (rtx *) alloca (nregs * sizeof (rtx)); | |
2858 | register rtx insn; | |
2859 | register int count = 0; | |
2860 | register rtx dest; | |
2861 | ||
2862 | bzero (last_set, nregs * sizeof (rtx)); | |
2863 | for (insn = from; insn != to; insn = NEXT_INSN (insn)) | |
2864 | { | |
2865 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
2866 | { | |
2867 | ++count; | |
2868 | ||
2869 | /* If requested, record registers that have exactly one use. */ | |
2870 | if (single_usage) | |
2871 | { | |
2872 | find_single_use_in_loop (insn, PATTERN (insn), single_usage); | |
2873 | ||
2874 | /* Include uses in REG_EQUAL notes. */ | |
2875 | if (REG_NOTES (insn)) | |
2876 | find_single_use_in_loop (insn, REG_NOTES (insn), single_usage); | |
2877 | } | |
2878 | ||
2879 | if (GET_CODE (PATTERN (insn)) == CLOBBER | |
2880 | && GET_CODE (XEXP (PATTERN (insn), 0)) == REG) | |
2881 | /* Don't move a reg that has an explicit clobber. | |
2882 | We might do so sometimes, but it's not worth the pain. */ | |
2883 | may_not_move[REGNO (XEXP (PATTERN (insn), 0))] = 1; | |
2884 | ||
2885 | if (GET_CODE (PATTERN (insn)) == SET | |
2886 | || GET_CODE (PATTERN (insn)) == CLOBBER) | |
2887 | { | |
2888 | dest = SET_DEST (PATTERN (insn)); | |
2889 | while (GET_CODE (dest) == SUBREG | |
2890 | || GET_CODE (dest) == ZERO_EXTRACT | |
2891 | || GET_CODE (dest) == SIGN_EXTRACT | |
2892 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2893 | dest = XEXP (dest, 0); | |
2894 | if (GET_CODE (dest) == REG) | |
2895 | { | |
2896 | register int regno = REGNO (dest); | |
2897 | /* If this is the first setting of this reg | |
2898 | in current basic block, and it was set before, | |
2899 | it must be set in two basic blocks, so it cannot | |
2900 | be moved out of the loop. */ | |
2901 | if (n_times_set[regno] > 0 && last_set[regno] == 0) | |
2902 | may_not_move[regno] = 1; | |
2903 | /* If this is not first setting in current basic block, | |
2904 | see if reg was used in between previous one and this. | |
2905 | If so, neither one can be moved. */ | |
2906 | if (last_set[regno] != 0 | |
2907 | && reg_used_between_p (dest, last_set[regno], insn)) | |
2908 | may_not_move[regno] = 1; | |
2909 | if (n_times_set[regno] < 127) | |
2910 | ++n_times_set[regno]; | |
2911 | last_set[regno] = insn; | |
2912 | } | |
2913 | } | |
2914 | else if (GET_CODE (PATTERN (insn)) == PARALLEL) | |
2915 | { | |
2916 | register int i; | |
2917 | for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) | |
2918 | { | |
2919 | register rtx x = XVECEXP (PATTERN (insn), 0, i); | |
2920 | if (GET_CODE (x) == CLOBBER && GET_CODE (XEXP (x, 0)) == REG) | |
2921 | /* Don't move a reg that has an explicit clobber. | |
2922 | It's not worth the pain to try to do it correctly. */ | |
2923 | may_not_move[REGNO (XEXP (x, 0))] = 1; | |
2924 | ||
2925 | if (GET_CODE (x) == SET || GET_CODE (x) == CLOBBER) | |
2926 | { | |
2927 | dest = SET_DEST (x); | |
2928 | while (GET_CODE (dest) == SUBREG | |
2929 | || GET_CODE (dest) == ZERO_EXTRACT | |
2930 | || GET_CODE (dest) == SIGN_EXTRACT | |
2931 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2932 | dest = XEXP (dest, 0); | |
2933 | if (GET_CODE (dest) == REG) | |
2934 | { | |
2935 | register int regno = REGNO (dest); | |
2936 | if (n_times_set[regno] > 0 && last_set[regno] == 0) | |
2937 | may_not_move[regno] = 1; | |
2938 | if (last_set[regno] != 0 | |
2939 | && reg_used_between_p (dest, last_set[regno], insn)) | |
2940 | may_not_move[regno] = 1; | |
2941 | if (n_times_set[regno] < 127) | |
2942 | ++n_times_set[regno]; | |
2943 | last_set[regno] = insn; | |
2944 | } | |
2945 | } | |
2946 | } | |
2947 | } | |
2948 | } | |
2949 | if (GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == JUMP_INSN) | |
2950 | bzero (last_set, nregs * sizeof (rtx)); | |
2951 | } | |
2952 | *count_ptr = count; | |
2953 | } | |
2954 | \f | |
2955 | /* Given a loop that is bounded by LOOP_START and LOOP_END | |
2956 | and that is entered at SCAN_START, | |
2957 | return 1 if the register set in SET contained in insn INSN is used by | |
2958 | any insn that precedes INSN in cyclic order starting | |
2959 | from the loop entry point. | |
2960 | ||
2961 | We don't want to use INSN_LUID here because if we restrict INSN to those | |
2962 | that have a valid INSN_LUID, it means we cannot move an invariant out | |
2963 | from an inner loop past two loops. */ | |
2964 | ||
2965 | static int | |
2966 | loop_reg_used_before_p (set, insn, loop_start, scan_start, loop_end) | |
2967 | rtx set, insn, loop_start, scan_start, loop_end; | |
2968 | { | |
2969 | rtx reg = SET_DEST (set); | |
2970 | rtx p; | |
2971 | ||
2972 | /* Scan forward checking for register usage. If we hit INSN, we | |
2973 | are done. Otherwise, if we hit LOOP_END, wrap around to LOOP_START. */ | |
2974 | for (p = scan_start; p != insn; p = NEXT_INSN (p)) | |
2975 | { | |
2976 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i' | |
2977 | && reg_overlap_mentioned_p (reg, PATTERN (p))) | |
2978 | return 1; | |
2979 | ||
2980 | if (p == loop_end) | |
2981 | p = loop_start; | |
2982 | } | |
2983 | ||
2984 | return 0; | |
2985 | } | |
2986 | \f | |
2987 | /* A "basic induction variable" or biv is a pseudo reg that is set | |
2988 | (within this loop) only by incrementing or decrementing it. */ | |
2989 | /* A "general induction variable" or giv is a pseudo reg whose | |
2990 | value is a linear function of a biv. */ | |
2991 | ||
2992 | /* Bivs are recognized by `basic_induction_var'; | |
2993 | Givs by `general_induct_var'. */ | |
2994 | ||
2995 | /* Indexed by register number, indicates whether or not register is an | |
2996 | induction variable, and if so what type. */ | |
2997 | ||
2998 | enum iv_mode *reg_iv_type; | |
2999 | ||
3000 | /* Indexed by register number, contains pointer to `struct induction' | |
3001 | if register is an induction variable. This holds general info for | |
3002 | all induction variables. */ | |
3003 | ||
3004 | struct induction **reg_iv_info; | |
3005 | ||
3006 | /* Indexed by register number, contains pointer to `struct iv_class' | |
3007 | if register is a basic induction variable. This holds info describing | |
3008 | the class (a related group) of induction variables that the biv belongs | |
3009 | to. */ | |
3010 | ||
3011 | struct iv_class **reg_biv_class; | |
3012 | ||
3013 | /* The head of a list which links together (via the next field) | |
3014 | every iv class for the current loop. */ | |
3015 | ||
3016 | struct iv_class *loop_iv_list; | |
3017 | ||
3018 | /* Communication with routines called via `note_stores'. */ | |
3019 | ||
3020 | static rtx note_insn; | |
3021 | ||
3022 | /* Dummy register to have non-zero DEST_REG for DEST_ADDR type givs. */ | |
3023 | ||
3024 | static rtx addr_placeholder; | |
3025 | ||
3026 | /* ??? Unfinished optimizations, and possible future optimizations, | |
3027 | for the strength reduction code. */ | |
3028 | ||
3029 | /* ??? There is one more optimization you might be interested in doing: to | |
3030 | allocate pseudo registers for frequently-accessed memory locations. | |
3031 | If the same memory location is referenced each time around, it might | |
3032 | be possible to copy it into a register before and out after. | |
3033 | This is especially useful when the memory location is a variable which | |
3034 | is in a stack slot because somewhere its address is taken. If the | |
3035 | loop doesn't contain a function call and the variable isn't volatile, | |
3036 | it is safe to keep the value in a register for the duration of the | |
3037 | loop. One tricky thing is that the copying of the value back from the | |
3038 | register has to be done on all exits from the loop. You need to check that | |
3039 | all the exits from the loop go to the same place. */ | |
3040 | ||
3041 | /* ??? The interaction of biv elimination, and recognition of 'constant' | |
3042 | bivs, may cause problems. */ | |
3043 | ||
3044 | /* ??? Add heuristics so that DEST_ADDR strength reduction does not cause | |
3045 | performance problems. | |
3046 | ||
3047 | Perhaps don't eliminate things that can be combined with an addressing | |
3048 | mode. Find all givs that have the same biv, mult_val, and add_val; | |
3049 | then for each giv, check to see if its only use dies in a following | |
3050 | memory address. If so, generate a new memory address and check to see | |
3051 | if it is valid. If it is valid, then store the modified memory address, | |
3052 | otherwise, mark the giv as not done so that it will get its own iv. */ | |
3053 | ||
3054 | /* ??? Could try to optimize branches when it is known that a biv is always | |
3055 | positive. */ | |
3056 | ||
3057 | /* ??? When replace a biv in a compare insn, we should replace with closest | |
3058 | giv so that an optimized branch can still be recognized by the combiner, | |
3059 | e.g. the VAX acb insn. */ | |
3060 | ||
3061 | /* ??? Many of the checks involving uid_luid could be simplified if regscan | |
3062 | was rerun in loop_optimize whenever a register was added or moved. | |
3063 | Also, some of the optimizations could be a little less conservative. */ | |
3064 | \f | |
3065 | /* Perform strength reduction and induction variable elimination. */ | |
3066 | ||
3067 | /* Pseudo registers created during this function will be beyond the last | |
3068 | valid index in several tables including n_times_set and regno_last_uid. | |
3069 | This does not cause a problem here, because the added registers cannot be | |
3070 | givs outside of their loop, and hence will never be reconsidered. | |
3071 | But scan_loop must check regnos to make sure they are in bounds. */ | |
3072 | ||
3073 | static void | |
3074 | strength_reduce (scan_start, end, loop_top, insn_count, | |
3075 | loop_start, loop_end) | |
3076 | rtx scan_start; | |
3077 | rtx end; | |
3078 | rtx loop_top; | |
3079 | int insn_count; | |
3080 | rtx loop_start; | |
3081 | rtx loop_end; | |
3082 | { | |
3083 | rtx p; | |
3084 | rtx set; | |
3085 | rtx inc_val; | |
3086 | rtx mult_val; | |
3087 | rtx dest_reg; | |
3088 | /* This is 1 if current insn is not executed at least once for every loop | |
3089 | iteration. */ | |
3090 | int not_every_iteration = 0; | |
3091 | /* This is 1 if current insn may be executed more than once for every | |
3092 | loop iteration. */ | |
3093 | int maybe_multiple = 0; | |
3094 | /* Temporary list pointers for traversing loop_iv_list. */ | |
3095 | struct iv_class *bl, **backbl; | |
3096 | /* Ratio of extra register life span we can justify | |
3097 | for saving an instruction. More if loop doesn't call subroutines | |
3098 | since in that case saving an insn makes more difference | |
3099 | and more registers are available. */ | |
3100 | /* ??? could set this to last value of threshold in move_movables */ | |
3101 | int threshold = (loop_has_call ? 1 : 2) * (3 + n_non_fixed_regs); | |
3102 | /* Map of pseudo-register replacements. */ | |
3103 | rtx *reg_map; | |
3104 | int call_seen; | |
3105 | rtx test; | |
3106 | rtx end_insert_before; | |
3107 | ||
3108 | reg_iv_type = (enum iv_mode *) alloca (max_reg_before_loop | |
3109 | * sizeof (enum iv_mode *)); | |
3110 | bzero ((char *) reg_iv_type, max_reg_before_loop * sizeof (enum iv_mode *)); | |
3111 | reg_iv_info = (struct induction **) | |
3112 | alloca (max_reg_before_loop * sizeof (struct induction *)); | |
3113 | bzero ((char *) reg_iv_info, (max_reg_before_loop | |
3114 | * sizeof (struct induction *))); | |
3115 | reg_biv_class = (struct iv_class **) | |
3116 | alloca (max_reg_before_loop * sizeof (struct iv_class *)); | |
3117 | bzero ((char *) reg_biv_class, (max_reg_before_loop | |
3118 | * sizeof (struct iv_class *))); | |
3119 | ||
3120 | loop_iv_list = 0; | |
3121 | addr_placeholder = gen_reg_rtx (Pmode); | |
3122 | ||
3123 | /* Save insn immediately after the loop_end. Insns inserted after loop_end | |
3124 | must be put before this insn, so that they will appear in the right | |
3125 | order (i.e. loop order). */ | |
3126 | ||
3127 | end_insert_before = NEXT_INSN (loop_end); | |
3128 | ||
3129 | /* Scan through loop to find all possible bivs. */ | |
3130 | ||
3131 | p = scan_start; | |
3132 | while (1) | |
3133 | { | |
3134 | p = NEXT_INSN (p); | |
3135 | /* At end of a straight-in loop, we are done. | |
3136 | At end of a loop entered at the bottom, scan the top. */ | |
3137 | if (p == scan_start) | |
3138 | break; | |
3139 | if (p == end) | |
3140 | { | |
3141 | if (loop_top != 0) | |
3142 | p = NEXT_INSN (loop_top); | |
3143 | else | |
3144 | break; | |
3145 | if (p == scan_start) | |
3146 | break; | |
3147 | } | |
3148 | ||
3149 | if (GET_CODE (p) == INSN | |
3150 | && (set = single_set (p)) | |
3151 | && GET_CODE (SET_DEST (set)) == REG) | |
3152 | { | |
3153 | dest_reg = SET_DEST (set); | |
3154 | if (REGNO (dest_reg) < max_reg_before_loop | |
3155 | && REGNO (dest_reg) >= FIRST_PSEUDO_REGISTER | |
3156 | && reg_iv_type[REGNO (dest_reg)] != NOT_BASIC_INDUCT) | |
3157 | { | |
3158 | if (basic_induction_var (SET_SRC (set), dest_reg, p, | |
3159 | &inc_val, &mult_val)) | |
3160 | { | |
3161 | /* It is a possible basic induction variable. | |
3162 | Create and initialize an induction structure for it. */ | |
3163 | ||
3164 | struct induction *v | |
3165 | = (struct induction *) alloca (sizeof (struct induction)); | |
3166 | ||
3167 | record_biv (v, p, dest_reg, inc_val, mult_val, | |
3168 | not_every_iteration, maybe_multiple); | |
3169 | reg_iv_type[REGNO (dest_reg)] = BASIC_INDUCT; | |
3170 | } | |
3171 | else if (REGNO (dest_reg) < max_reg_before_loop) | |
3172 | reg_iv_type[REGNO (dest_reg)] = NOT_BASIC_INDUCT; | |
3173 | } | |
3174 | } | |
3175 | ||
3176 | /* Past CODE_LABEL, we get to insns that may be executed multiple | |
3177 | times. The only way we can be sure that they can't is if every | |
3178 | every jump insn between here and the end of the loop either | |
3179 | returns, exits the loop, or is a forward jump. */ | |
3180 | ||
3181 | if (GET_CODE (p) == CODE_LABEL) | |
3182 | { | |
3183 | rtx insn = p; | |
3184 | ||
3185 | maybe_multiple = 0; | |
3186 | ||
3187 | while (1) | |
3188 | { | |
3189 | insn = NEXT_INSN (insn); | |
3190 | if (insn == scan_start) | |
3191 | break; | |
3192 | if (insn == end) | |
3193 | { | |
3194 | if (loop_top != 0) | |
3195 | insn = NEXT_INSN (loop_top); | |
3196 | else | |
3197 | break; | |
3198 | if (insn == scan_start) | |
3199 | break; | |
3200 | } | |
3201 | ||
3202 | if (GET_CODE (insn) == JUMP_INSN | |
3203 | && GET_CODE (PATTERN (insn)) != RETURN | |
3204 | && (! condjump_p (insn) | |
3205 | || (JUMP_LABEL (insn) != 0 | |
3206 | && (INSN_UID (JUMP_LABEL (insn)) >= max_uid_for_loop | |
3207 | || INSN_UID (insn) >= max_uid_for_loop | |
3208 | || (INSN_LUID (JUMP_LABEL (insn)) | |
3209 | < INSN_LUID (insn)))))) | |
3210 | { | |
3211 | maybe_multiple = 1; | |
3212 | break; | |
3213 | } | |
3214 | } | |
3215 | } | |
3216 | ||
3217 | /* Past a label or a jump, we get to insns for which we can't count | |
3218 | on whether or how many times they will be executed during each | |
3219 | iteration. */ | |
3220 | /* This code appears in three places, once in scan_loop, and twice | |
3221 | in strength_reduce. */ | |
3222 | if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) | |
3223 | /* If we enter the loop in the middle, and scan around to the | |
3224 | beginning, don't set not_every_iteration for that. | |
3225 | This can be any kind of jump, since we want to know if insns | |
3226 | will be executed if the loop is executed. */ | |
3227 | && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top | |
3228 | && ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p)) | |
3229 | || (NEXT_INSN (p) == loop_end && condjump_p (p))))) | |
3230 | not_every_iteration = 1; | |
3231 | ||
3232 | /* At the virtual top of a converted loop, insns are again known to | |
3233 | be executed each iteration: logically, the loop begins here | |
3234 | even though the exit code has been duplicated. */ | |
3235 | ||
3236 | else if (GET_CODE (p) == NOTE | |
3237 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP) | |
3238 | not_every_iteration = 0; | |
3239 | ||
3240 | /* Unlike in the code motion pass where MAYBE_NEVER indicates that | |
3241 | an insn may never be executed, NOT_EVERY_ITERATION indicates whether | |
3242 | or not an insn is known to be executed each iteration of the | |
3243 | loop, whether or not any iterations are known to occur. | |
3244 | ||
3245 | Therefore, if we have just passed a label and have no more labels | |
3246 | between here and the test insn of the loop, we know these insns | |
3247 | will be executed each iteration. This can also happen if we | |
3248 | have just passed a jump, for example, when there are nested loops. */ | |
3249 | ||
3250 | if (not_every_iteration && GET_CODE (p) == CODE_LABEL | |
3251 | && no_labels_between_p (p, loop_end)) | |
3252 | not_every_iteration = 0; | |
3253 | } | |
3254 | ||
3255 | /* Scan loop_iv_list to remove all regs that proved not to be bivs. | |
3256 | Make a sanity check against n_times_set. */ | |
3257 | for (backbl = &loop_iv_list, bl = *backbl; bl; bl = bl->next) | |
3258 | { | |
3259 | if (reg_iv_type[bl->regno] != BASIC_INDUCT | |
3260 | /* Above happens if register modified by subreg, etc. */ | |
3261 | /* Make sure it is not recognized as a basic induction var: */ | |
3262 | || n_times_set[bl->regno] != bl->biv_count | |
3263 | /* If never incremented, it is invariant that we decided not to | |
3264 | move. So leave it alone. */ | |
3265 | || ! bl->incremented) | |
3266 | { | |
3267 | if (loop_dump_stream) | |
3268 | fprintf (loop_dump_stream, "Reg %d: biv discarded, %s\n", | |
3269 | bl->regno, | |
3270 | (reg_iv_type[bl->regno] != BASIC_INDUCT | |
3271 | ? "not induction variable" | |
3272 | : (! bl->incremented ? "never incremented" | |
3273 | : "count error"))); | |
3274 | ||
3275 | reg_iv_type[bl->regno] = NOT_BASIC_INDUCT; | |
3276 | *backbl = bl->next; | |
3277 | } | |
3278 | else | |
3279 | { | |
3280 | backbl = &bl->next; | |
3281 | ||
3282 | if (loop_dump_stream) | |
3283 | fprintf (loop_dump_stream, "Reg %d: biv verified\n", bl->regno); | |
3284 | } | |
3285 | } | |
3286 | ||
3287 | /* Exit if there are no bivs. */ | |
3288 | if (! loop_iv_list) | |
3289 | { | |
3290 | /* Can still unroll the loop anyways, but indicate that there is no | |
3291 | strength reduction info available. */ | |
3292 | if (flag_unroll_loops) | |
3293 | unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 0); | |
3294 | ||
3295 | return; | |
3296 | } | |
3297 | ||
3298 | /* Find initial value for each biv by searching backwards from loop_start, | |
3299 | halting at first label. Also record any test condition. */ | |
3300 | ||
3301 | call_seen = 0; | |
3302 | for (p = loop_start; p && GET_CODE (p) != CODE_LABEL; p = PREV_INSN (p)) | |
3303 | { | |
3304 | note_insn = p; | |
3305 | ||
3306 | if (GET_CODE (p) == CALL_INSN) | |
3307 | call_seen = 1; | |
3308 | ||
3309 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
3310 | || GET_CODE (p) == CALL_INSN) | |
3311 | note_stores (PATTERN (p), record_initial); | |
3312 | ||
3313 | /* Record any test of a biv that branches around the loop if no store | |
3314 | between it and the start of loop. We only care about tests with | |
3315 | constants and registers and only certain of those. */ | |
3316 | if (GET_CODE (p) == JUMP_INSN | |
3317 | && JUMP_LABEL (p) != 0 | |
3318 | && next_real_insn (JUMP_LABEL (p)) == next_real_insn (loop_end) | |
3319 | && (test = get_condition_for_loop (p)) != 0 | |
3320 | && GET_CODE (XEXP (test, 0)) == REG | |
3321 | && REGNO (XEXP (test, 0)) < max_reg_before_loop | |
3322 | && (bl = reg_biv_class[REGNO (XEXP (test, 0))]) != 0 | |
3323 | && valid_initial_value_p (XEXP (test, 1), p, call_seen, loop_start) | |
3324 | && bl->init_insn == 0) | |
3325 | { | |
3326 | /* If an NE test, we have an initial value! */ | |
3327 | if (GET_CODE (test) == NE) | |
3328 | { | |
3329 | bl->init_insn = p; | |
3330 | bl->init_set = gen_rtx (SET, VOIDmode, | |
3331 | XEXP (test, 0), XEXP (test, 1)); | |
3332 | } | |
3333 | else | |
3334 | bl->initial_test = test; | |
3335 | } | |
3336 | } | |
3337 | ||
3338 | /* Look at the each biv and see if we can say anything better about its | |
3339 | initial value from any initializing insns set up above. (This is done | |
3340 | in two passes to avoid missing SETs in a PARALLEL.) */ | |
3341 | for (bl = loop_iv_list; bl; bl = bl->next) | |
3342 | { | |
3343 | rtx src; | |
3344 | ||
3345 | if (! bl->init_insn) | |
3346 | continue; | |
3347 | ||
3348 | src = SET_SRC (bl->init_set); | |
3349 | ||
3350 | if (loop_dump_stream) | |
3351 | fprintf (loop_dump_stream, | |
3352 | "Biv %d initialized at insn %d: initial value ", | |
3353 | bl->regno, INSN_UID (bl->init_insn)); | |
3354 | ||
3355 | if (valid_initial_value_p (src, bl->init_insn, call_seen, loop_start)) | |
3356 | { | |
3357 | bl->initial_value = src; | |
3358 | ||
3359 | if (loop_dump_stream) | |
3360 | { | |
3361 | if (GET_CODE (src) == CONST_INT) | |
3362 | fprintf (loop_dump_stream, "%d\n", INTVAL (src)); | |
3363 | else | |
3364 | { | |
3365 | print_rtl (loop_dump_stream, src); | |
3366 | fprintf (loop_dump_stream, "\n"); | |
3367 | } | |
3368 | } | |
3369 | } | |
3370 | else | |
3371 | { | |
3372 | /* Biv initial value is not simple move, | |
3373 | so let it keep initial value of "itself". */ | |
3374 | ||
3375 | if (loop_dump_stream) | |
3376 | fprintf (loop_dump_stream, "is complex\n"); | |
3377 | } | |
3378 | } | |
3379 | ||
3380 | /* Search the loop for general induction variables. */ | |
3381 | ||
3382 | /* A register is a giv if: it is only set once, it is a function of a | |
3383 | biv and a constant (or invariant), and it is not a biv. */ | |
3384 | ||
3385 | not_every_iteration = 0; | |
3386 | p = scan_start; | |
3387 | while (1) | |
3388 | { | |
3389 | p = NEXT_INSN (p); | |
3390 | /* At end of a straight-in loop, we are done. | |
3391 | At end of a loop entered at the bottom, scan the top. */ | |
3392 | if (p == scan_start) | |
3393 | break; | |
3394 | if (p == end) | |
3395 | { | |
3396 | if (loop_top != 0) | |
3397 | p = NEXT_INSN (loop_top); | |
3398 | else | |
3399 | break; | |
3400 | if (p == scan_start) | |
3401 | break; | |
3402 | } | |
3403 | ||
3404 | /* Look for a general induction variable in a register. */ | |
3405 | if (GET_CODE (p) == INSN | |
3406 | && (set = single_set (p)) | |
3407 | && GET_CODE (SET_DEST (set)) == REG | |
3408 | && ! may_not_optimize[REGNO (SET_DEST (set))]) | |
3409 | { | |
3410 | rtx src_reg; | |
3411 | rtx add_val; | |
3412 | rtx mult_val; | |
3413 | int benefit; | |
3414 | rtx regnote = 0; | |
3415 | ||
3416 | dest_reg = SET_DEST (set); | |
3417 | if (REGNO (dest_reg) < FIRST_PSEUDO_REGISTER) | |
3418 | continue; | |
3419 | ||
3420 | if (/* SET_SRC is a giv. */ | |
3421 | ((benefit = general_induction_var (SET_SRC (set), | |
3422 | &src_reg, &add_val, | |
3423 | &mult_val)) | |
3424 | /* Equivalent expression is a giv. */ | |
3425 | || ((regnote = find_reg_note (p, REG_EQUAL, NULL_RTX)) | |
3426 | && (benefit = general_induction_var (XEXP (regnote, 0), | |
3427 | &src_reg, | |
3428 | &add_val, &mult_val)))) | |
3429 | /* Don't try to handle any regs made by loop optimization. | |
3430 | We have nothing on them in regno_first_uid, etc. */ | |
3431 | && REGNO (dest_reg) < max_reg_before_loop | |
3432 | /* Don't recognize a BASIC_INDUCT_VAR here. */ | |
3433 | && dest_reg != src_reg | |
3434 | /* This must be the only place where the register is set. */ | |
3435 | && (n_times_set[REGNO (dest_reg)] == 1 | |
3436 | /* or all sets must be consecutive and make a giv. */ | |
3437 | || (benefit = consec_sets_giv (benefit, p, | |
3438 | src_reg, dest_reg, | |
3439 | &add_val, &mult_val)))) | |
3440 | { | |
3441 | int count; | |
3442 | struct induction *v | |
3443 | = (struct induction *) alloca (sizeof (struct induction)); | |
3444 | rtx temp; | |
3445 | ||
3446 | /* If this is a library call, increase benefit. */ | |
3447 | if (find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
3448 | benefit += libcall_benefit (p); | |
3449 | ||
3450 | /* Skip the consecutive insns, if there are any. */ | |
3451 | for (count = n_times_set[REGNO (dest_reg)] - 1; | |
3452 | count > 0; count--) | |
3453 | { | |
3454 | /* If first insn of libcall sequence, skip to end. | |
3455 | Do this at start of loop, since INSN is guaranteed to | |
3456 | be an insn here. */ | |
3457 | if (GET_CODE (p) != NOTE | |
3458 | && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
3459 | p = XEXP (temp, 0); | |
3460 | ||
3461 | do p = NEXT_INSN (p); | |
3462 | while (GET_CODE (p) == NOTE); | |
3463 | } | |
3464 | ||
3465 | record_giv (v, p, src_reg, dest_reg, mult_val, add_val, benefit, | |
3466 | DEST_REG, not_every_iteration, NULL_PTR, loop_start, | |
3467 | loop_end); | |
3468 | ||
3469 | } | |
3470 | } | |
3471 | ||
3472 | #ifndef DONT_REDUCE_ADDR | |
3473 | /* Look for givs which are memory addresses. */ | |
3474 | /* This resulted in worse code on a VAX 8600. I wonder if it | |
3475 | still does. */ | |
3476 | if (GET_CODE (p) == INSN) | |
3477 | find_mem_givs (PATTERN (p), p, not_every_iteration, loop_start, | |
3478 | loop_end); | |
3479 | #endif | |
3480 | ||
3481 | /* Update the status of whether giv can derive other givs. This can | |
3482 | change when we pass a label or an insn that updates a biv. */ | |
3483 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
3484 | || GET_CODE (p) == CODE_LABEL) | |
3485 | update_giv_derive (p); | |
3486 | ||
3487 | /* Past a label or a jump, we get to insns for which we can't count | |
3488 | on whether or how many times they will be executed during each | |
3489 | iteration. */ | |
3490 | /* This code appears in three places, once in scan_loop, and twice | |
3491 | in strength_reduce. */ | |
3492 | if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) | |
3493 | /* If we enter the loop in the middle, and scan around | |
3494 | to the beginning, don't set not_every_iteration for that. | |
3495 | This can be any kind of jump, since we want to know if insns | |
3496 | will be executed if the loop is executed. */ | |
3497 | && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top | |
3498 | && ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p)) | |
3499 | || (NEXT_INSN (p) == loop_end && condjump_p (p))))) | |
3500 | not_every_iteration = 1; | |
3501 | ||
3502 | /* At the virtual top of a converted loop, insns are again known to | |
3503 | be executed each iteration: logically, the loop begins here | |
3504 | even though the exit code has been duplicated. */ | |
3505 | ||
3506 | else if (GET_CODE (p) == NOTE | |
3507 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP) | |
3508 | not_every_iteration = 0; | |
3509 | ||
3510 | /* Unlike in the code motion pass where MAYBE_NEVER indicates that | |
3511 | an insn may never be executed, NOT_EVERY_ITERATION indicates whether | |
3512 | or not an insn is known to be executed each iteration of the | |
3513 | loop, whether or not any iterations are known to occur. | |
3514 | ||
3515 | Therefore, if we have just passed a label and have no more labels | |
3516 | between here and the test insn of the loop, we know these insns | |
3517 | will be executed each iteration. */ | |
3518 | ||
3519 | if (not_every_iteration && GET_CODE (p) == CODE_LABEL | |
3520 | && no_labels_between_p (p, loop_end)) | |
3521 | not_every_iteration = 0; | |
3522 | } | |
3523 | ||
3524 | /* Try to calculate and save the number of loop iterations. This is | |
3525 | set to zero if the actual number can not be calculated. This must | |
3526 | be called after all giv's have been identified, since otherwise it may | |
3527 | fail if the iteration variable is a giv. */ | |
3528 | ||
3529 | loop_n_iterations = loop_iterations (loop_start, loop_end); | |
3530 | ||
3531 | /* Now for each giv for which we still don't know whether or not it is | |
3532 | replaceable, check to see if it is replaceable because its final value | |
3533 | can be calculated. This must be done after loop_iterations is called, | |
3534 | so that final_giv_value will work correctly. */ | |
3535 | ||
3536 | for (bl = loop_iv_list; bl; bl = bl->next) | |
3537 | { | |
3538 | struct induction *v; | |
3539 | ||
3540 | for (v = bl->giv; v; v = v->next_iv) | |
3541 | if (! v->replaceable && ! v->not_replaceable) | |
3542 | check_final_value (v, loop_start, loop_end); | |
3543 | } | |
3544 | ||
3545 | /* Try to prove that the loop counter variable (if any) is always | |
3546 | nonnegative; if so, record that fact with a REG_NONNEG note | |
3547 | so that "decrement and branch until zero" insn can be used. */ | |
3548 | check_dbra_loop (loop_end, insn_count, loop_start); | |
3549 | ||
3550 | /* Create reg_map to hold substitutions for replaceable giv regs. */ | |
3551 | reg_map = (rtx *) alloca (max_reg_before_loop * sizeof (rtx)); | |
3552 | bzero ((char *) reg_map, max_reg_before_loop * sizeof (rtx)); | |
3553 | ||
3554 | /* Examine each iv class for feasibility of strength reduction/induction | |
3555 | variable elimination. */ | |
3556 | ||
3557 | for (bl = loop_iv_list; bl; bl = bl->next) | |
3558 | { | |
3559 | struct induction *v; | |
3560 | int benefit; | |
3561 | int all_reduced; | |
3562 | rtx final_value = 0; | |
3563 | ||
3564 | /* Test whether it will be possible to eliminate this biv | |
3565 | provided all givs are reduced. This is possible if either | |
3566 | the reg is not used outside the loop, or we can compute | |
3567 | what its final value will be. | |
3568 | ||
3569 | For architectures with a decrement_and_branch_until_zero insn, | |
3570 | don't do this if we put a REG_NONNEG note on the endtest for | |
3571 | this biv. */ | |
3572 | ||
3573 | /* Compare against bl->init_insn rather than loop_start. | |
3574 | We aren't concerned with any uses of the biv between | |
3575 | init_insn and loop_start since these won't be affected | |
3576 | by the value of the biv elsewhere in the function, so | |
3577 | long as init_insn doesn't use the biv itself. | |
3578 | March 14, 1989 -- self@bayes.arc.nasa.gov */ | |
3579 | ||
3580 | if ((uid_luid[regno_last_uid[bl->regno]] < INSN_LUID (loop_end) | |
3581 | && bl->init_insn | |
3582 | && INSN_UID (bl->init_insn) < max_uid_for_loop | |
3583 | && uid_luid[regno_first_uid[bl->regno]] >= INSN_LUID (bl->init_insn) | |
3584 | #ifdef HAVE_decrement_and_branch_until_zero | |
3585 | && ! bl->nonneg | |
3586 | #endif | |
3587 | && ! reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set))) | |
3588 | || ((final_value = final_biv_value (bl, loop_start, loop_end)) | |
3589 | #ifdef HAVE_decrement_and_branch_until_zero | |
3590 | && ! bl->nonneg | |
3591 | #endif | |
3592 | )) | |
3593 | bl->eliminable = maybe_eliminate_biv (bl, loop_start, end, 0, | |
3594 | threshold, insn_count); | |
3595 | else | |
3596 | { | |
3597 | if (loop_dump_stream) | |
3598 | { | |
3599 | fprintf (loop_dump_stream, | |
3600 | "Cannot eliminate biv %d.\n", | |
3601 | bl->regno); | |
3602 | fprintf (loop_dump_stream, | |
3603 | "First use: insn %d, last use: insn %d.\n", | |
3604 | regno_first_uid[bl->regno], | |
3605 | regno_last_uid[bl->regno]); | |
3606 | } | |
3607 | } | |
3608 | ||
3609 | /* Combine all giv's for this iv_class. */ | |
3610 | combine_givs (bl); | |
3611 | ||
3612 | /* This will be true at the end, if all givs which depend on this | |
3613 | biv have been strength reduced. | |
3614 | We can't (currently) eliminate the biv unless this is so. */ | |
3615 | all_reduced = 1; | |
3616 | ||
3617 | /* Check each giv in this class to see if we will benefit by reducing | |
3618 | it. Skip giv's combined with others. */ | |
3619 | for (v = bl->giv; v; v = v->next_iv) | |
3620 | { | |
3621 | struct induction *tv; | |
3622 | ||
3623 | if (v->ignore || v->same) | |
3624 | continue; | |
3625 | ||
3626 | benefit = v->benefit; | |
3627 | ||
3628 | /* Reduce benefit if not replaceable, since we will insert | |
3629 | a move-insn to replace the insn that calculates this giv. | |
3630 | Don't do this unless the giv is a user variable, since it | |
3631 | will often be marked non-replaceable because of the duplication | |
3632 | of the exit code outside the loop. In such a case, the copies | |
3633 | we insert are dead and will be deleted. So they don't have | |
3634 | a cost. Similar situations exist. */ | |
3635 | /* ??? The new final_[bg]iv_value code does a much better job | |
3636 | of finding replaceable giv's, and hence this code may no longer | |
3637 | be necessary. */ | |
3638 | if (! v->replaceable && ! bl->eliminable | |
3639 | && REG_USERVAR_P (v->dest_reg)) | |
3640 | benefit -= copy_cost; | |
3641 | ||
3642 | /* Decrease the benefit to count the add-insns that we will | |
3643 | insert to increment the reduced reg for the giv. */ | |
3644 | benefit -= add_cost * bl->biv_count; | |
3645 | ||
3646 | /* Decide whether to strength-reduce this giv or to leave the code | |
3647 | unchanged (recompute it from the biv each time it is used). | |
3648 | This decision can be made independently for each giv. */ | |
3649 | ||
3650 | /* ??? Perhaps attempt to guess whether autoincrement will handle | |
3651 | some of the new add insns; if so, can increase BENEFIT | |
3652 | (undo the subtraction of add_cost that was done above). */ | |
3653 | ||
3654 | /* If an insn is not to be strength reduced, then set its ignore | |
3655 | flag, and clear all_reduced. */ | |
3656 | ||
3657 | if (v->lifetime * threshold * benefit < insn_count) | |
3658 | { | |
3659 | if (loop_dump_stream) | |
3660 | fprintf (loop_dump_stream, | |
3661 | "giv of insn %d not worth while, %d vs %d.\n", | |
3662 | INSN_UID (v->insn), | |
3663 | v->lifetime * threshold * benefit, insn_count); | |
3664 | v->ignore = 1; | |
3665 | all_reduced = 0; | |
3666 | } | |
3667 | else | |
3668 | { | |
3669 | /* Check that we can increment the reduced giv without a | |
3670 | multiply insn. If not, reject it. */ | |
3671 | ||
3672 | for (tv = bl->biv; tv; tv = tv->next_iv) | |
3673 | if (tv->mult_val == const1_rtx | |
3674 | && ! product_cheap_p (tv->add_val, v->mult_val)) | |
3675 | { | |
3676 | if (loop_dump_stream) | |
3677 | fprintf (loop_dump_stream, | |
3678 | "giv of insn %d: would need a multiply.\n", | |
3679 | INSN_UID (v->insn)); | |
3680 | v->ignore = 1; | |
3681 | all_reduced = 0; | |
3682 | break; | |
3683 | } | |
3684 | } | |
3685 | } | |
3686 | ||
3687 | /* Reduce each giv that we decided to reduce. */ | |
3688 | ||
3689 | for (v = bl->giv; v; v = v->next_iv) | |
3690 | { | |
3691 | struct induction *tv; | |
3692 | if (! v->ignore && v->same == 0) | |
3693 | { | |
3694 | v->new_reg = gen_reg_rtx (v->mode); | |
3695 | ||
3696 | /* For each place where the biv is incremented, | |
3697 | add an insn to increment the new, reduced reg for the giv. */ | |
3698 | for (tv = bl->biv; tv; tv = tv->next_iv) | |
3699 | { | |
3700 | if (tv->mult_val == const1_rtx) | |
3701 | emit_iv_add_mult (tv->add_val, v->mult_val, | |
3702 | v->new_reg, v->new_reg, tv->insn); | |
3703 | else /* tv->mult_val == const0_rtx */ | |
3704 | /* A multiply is acceptable here | |
3705 | since this is presumed to be seldom executed. */ | |
3706 | emit_iv_add_mult (tv->add_val, v->mult_val, | |
3707 | v->add_val, v->new_reg, tv->insn); | |
3708 | } | |
3709 | ||
3710 | /* Add code at loop start to initialize giv's reduced reg. */ | |
3711 | ||
3712 | emit_iv_add_mult (bl->initial_value, v->mult_val, | |
3713 | v->add_val, v->new_reg, loop_start); | |
3714 | } | |
3715 | } | |
3716 | ||
3717 | /* Rescan all givs. If a giv is the same as a giv not reduced, mark it | |
3718 | as not reduced. | |
3719 | ||
3720 | For each giv register that can be reduced now: if replaceable, | |
3721 | substitute reduced reg wherever the old giv occurs; | |
3722 | else add new move insn "giv_reg = reduced_reg". | |
3723 | ||
3724 | Also check for givs whose first use is their definition and whose | |
3725 | last use is the definition of another giv. If so, it is likely | |
3726 | dead and should not be used to eliminate a biv. */ | |
3727 | for (v = bl->giv; v; v = v->next_iv) | |
3728 | { | |
3729 | if (v->same && v->same->ignore) | |
3730 | v->ignore = 1; | |
3731 | ||
3732 | if (v->ignore) | |
3733 | continue; | |
3734 | ||
3735 | if (v->giv_type == DEST_REG | |
3736 | && regno_first_uid[REGNO (v->dest_reg)] == INSN_UID (v->insn)) | |
3737 | { | |
3738 | struct induction *v1; | |
3739 | ||
3740 | for (v1 = bl->giv; v1; v1 = v1->next_iv) | |
3741 | if (regno_last_uid[REGNO (v->dest_reg)] == INSN_UID (v1->insn)) | |
3742 | v->maybe_dead = 1; | |
3743 | } | |
3744 | ||
3745 | /* Update expression if this was combined, in case other giv was | |
3746 | replaced. */ | |
3747 | if (v->same) | |
3748 | v->new_reg = replace_rtx (v->new_reg, | |
3749 | v->same->dest_reg, v->same->new_reg); | |
3750 | ||
3751 | if (v->giv_type == DEST_ADDR) | |
3752 | /* Store reduced reg as the address in the memref where we found | |
3753 | this giv. */ | |
3754 | *v->location = v->new_reg; | |
3755 | else if (v->replaceable) | |
3756 | { | |
3757 | reg_map[REGNO (v->dest_reg)] = v->new_reg; | |
3758 | ||
3759 | #if 0 | |
3760 | /* I can no longer duplicate the original problem. Perhaps | |
3761 | this is unnecessary now? */ | |
3762 | ||
3763 | /* Replaceable; it isn't strictly necessary to delete the old | |
3764 | insn and emit a new one, because v->dest_reg is now dead. | |
3765 | ||
3766 | However, especially when unrolling loops, the special | |
3767 | handling for (set REG0 REG1) in the second cse pass may | |
3768 | make v->dest_reg live again. To avoid this problem, emit | |
3769 | an insn to set the original giv reg from the reduced giv. | |
3770 | We can not delete the original insn, since it may be part | |
3771 | of a LIBCALL, and the code in flow that eliminates dead | |
3772 | libcalls will fail if it is deleted. */ | |
3773 | emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg), | |
3774 | v->insn); | |
3775 | #endif | |
3776 | } | |
3777 | else | |
3778 | { | |
3779 | /* Not replaceable; emit an insn to set the original giv reg from | |
3780 | the reduced giv, same as above. */ | |
3781 | emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg), | |
3782 | v->insn); | |
3783 | } | |
3784 | ||
3785 | /* When a loop is reversed, givs which depend on the reversed | |
3786 | biv, and which are live outside the loop, must be set to their | |
3787 | correct final value. This insn is only needed if the giv is | |
3788 | not replaceable. The correct final value is the same as the | |
3789 | value that the giv starts the reversed loop with. */ | |
3790 | if (bl->reversed && ! v->replaceable) | |
3791 | emit_iv_add_mult (bl->initial_value, v->mult_val, | |
3792 | v->add_val, v->dest_reg, end_insert_before); | |
3793 | else if (v->final_value) | |
3794 | { | |
3795 | rtx insert_before; | |
3796 | ||
3797 | /* If the loop has multiple exits, emit the insn before the | |
3798 | loop to ensure that it will always be executed no matter | |
3799 | how the loop exits. Otherwise, emit the insn after the loop, | |
3800 | since this is slightly more efficient. */ | |
3801 | if (loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
3802 | insert_before = loop_start; | |
3803 | else | |
3804 | insert_before = end_insert_before; | |
3805 | emit_insn_before (gen_move_insn (v->dest_reg, v->final_value), | |
3806 | insert_before); | |
3807 | ||
3808 | #if 0 | |
3809 | /* If the insn to set the final value of the giv was emitted | |
3810 | before the loop, then we must delete the insn inside the loop | |
3811 | that sets it. If this is a LIBCALL, then we must delete | |
3812 | every insn in the libcall. Note, however, that | |
3813 | final_giv_value will only succeed when there are multiple | |
3814 | exits if the giv is dead at each exit, hence it does not | |
3815 | matter that the original insn remains because it is dead | |
3816 | anyways. */ | |
3817 | /* Delete the insn inside the loop that sets the giv since | |
3818 | the giv is now set before (or after) the loop. */ | |
3819 | delete_insn (v->insn); | |
3820 | #endif | |
3821 | } | |
3822 | ||
3823 | if (loop_dump_stream) | |
3824 | { | |
3825 | fprintf (loop_dump_stream, "giv at %d reduced to ", | |
3826 | INSN_UID (v->insn)); | |
3827 | print_rtl (loop_dump_stream, v->new_reg); | |
3828 | fprintf (loop_dump_stream, "\n"); | |
3829 | } | |
3830 | } | |
3831 | ||
3832 | /* All the givs based on the biv bl have been reduced if they | |
3833 | merit it. */ | |
3834 | ||
3835 | /* For each giv not marked as maybe dead that has been combined with a | |
3836 | second giv, clear any "maybe dead" mark on that second giv. | |
3837 | v->new_reg will either be or refer to the register of the giv it | |
3838 | combined with. | |
3839 | ||
3840 | Doing this clearing avoids problems in biv elimination where a | |
3841 | giv's new_reg is a complex value that can't be put in the insn but | |
3842 | the giv combined with (with a reg as new_reg) is marked maybe_dead. | |
3843 | Since the register will be used in either case, we'd prefer it be | |
3844 | used from the simpler giv. */ | |
3845 | ||
3846 | for (v = bl->giv; v; v = v->next_iv) | |
3847 | if (! v->maybe_dead && v->same) | |
3848 | v->same->maybe_dead = 0; | |
3849 | ||
3850 | /* Try to eliminate the biv, if it is a candidate. | |
3851 | This won't work if ! all_reduced, | |
3852 | since the givs we planned to use might not have been reduced. | |
3853 | ||
3854 | We have to be careful that we didn't initially think we could eliminate | |
3855 | this biv because of a giv that we now think may be dead and shouldn't | |
3856 | be used as a biv replacement. | |
3857 | ||
3858 | Also, there is the possibility that we may have a giv that looks | |
3859 | like it can be used to eliminate a biv, but the resulting insn | |
3860 | isn't valid. This can happen, for example, on the 88k, where a | |
3861 | JUMP_INSN can compare a register only with zero. Attempts to | |
3862 | replace it with a compare with a constant will fail. | |
3863 | ||
3864 | Note that in cases where this call fails, we may have replaced some | |
3865 | of the occurrences of the biv with a giv, but no harm was done in | |
3866 | doing so in the rare cases where it can occur. */ | |
3867 | ||
3868 | if (all_reduced == 1 && bl->eliminable | |
3869 | && maybe_eliminate_biv (bl, loop_start, end, 1, | |
3870 | threshold, insn_count)) | |
3871 | ||
3872 | { | |
3873 | /* ?? If we created a new test to bypass the loop entirely, | |
3874 | or otherwise drop straight in, based on this test, then | |
3875 | we might want to rewrite it also. This way some later | |
3876 | pass has more hope of removing the initialization of this | |
3877 | biv entirely. */ | |
3878 | ||
3879 | /* If final_value != 0, then the biv may be used after loop end | |
3880 | and we must emit an insn to set it just in case. | |
3881 | ||
3882 | Reversed bivs already have an insn after the loop setting their | |
3883 | value, so we don't need another one. We can't calculate the | |
3884 | proper final value for such a biv here anyways. */ | |
3885 | if (final_value != 0 && ! bl->reversed) | |
3886 | { | |
3887 | rtx insert_before; | |
3888 | ||
3889 | /* If the loop has multiple exits, emit the insn before the | |
3890 | loop to ensure that it will always be executed no matter | |
3891 | how the loop exits. Otherwise, emit the insn after the | |
3892 | loop, since this is slightly more efficient. */ | |
3893 | if (loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
3894 | insert_before = loop_start; | |
3895 | else | |
3896 | insert_before = end_insert_before; | |
3897 | ||
3898 | emit_insn_before (gen_move_insn (bl->biv->dest_reg, final_value), | |
3899 | end_insert_before); | |
3900 | } | |
3901 | ||
3902 | #if 0 | |
3903 | /* Delete all of the instructions inside the loop which set | |
3904 | the biv, as they are all dead. If is safe to delete them, | |
3905 | because an insn setting a biv will never be part of a libcall. */ | |
3906 | /* However, deleting them will invalidate the regno_last_uid info, | |
3907 | so keeping them around is more convenient. Final_biv_value | |
3908 | will only succeed when there are multiple exits if the biv | |
3909 | is dead at each exit, hence it does not matter that the original | |
3910 | insn remains, because it is dead anyways. */ | |
3911 | for (v = bl->biv; v; v = v->next_iv) | |
3912 | delete_insn (v->insn); | |
3913 | #endif | |
3914 | ||
3915 | if (loop_dump_stream) | |
3916 | fprintf (loop_dump_stream, "Reg %d: biv eliminated\n", | |
3917 | bl->regno); | |
3918 | } | |
3919 | } | |
3920 | ||
3921 | /* Go through all the instructions in the loop, making all the | |
3922 | register substitutions scheduled in REG_MAP. */ | |
3923 | ||
3924 | for (p = loop_start; p != end; p = NEXT_INSN (p)) | |
3925 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
3926 | || GET_CODE (p) == CALL_INSN) | |
3927 | { | |
3928 | replace_regs (PATTERN (p), reg_map, max_reg_before_loop, 0); | |
3929 | replace_regs (REG_NOTES (p), reg_map, max_reg_before_loop, 0); | |
3930 | } | |
3931 | ||
3932 | /* Unroll loops from within strength reduction so that we can use the | |
3933 | induction variable information that strength_reduce has already | |
3934 | collected. */ | |
3935 | ||
3936 | if (flag_unroll_loops) | |
3937 | unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 1); | |
3938 | ||
3939 | if (loop_dump_stream) | |
3940 | fprintf (loop_dump_stream, "\n"); | |
3941 | } | |
3942 | \f | |
3943 | /* Return 1 if X is a valid source for an initial value (or as value being | |
3944 | compared against in an initial test). | |
3945 | ||
3946 | X must be either a register or constant and must not be clobbered between | |
3947 | the current insn and the start of the loop. | |
3948 | ||
3949 | INSN is the insn containing X. */ | |
3950 | ||
3951 | static int | |
3952 | valid_initial_value_p (x, insn, call_seen, loop_start) | |
3953 | rtx x; | |
3954 | rtx insn; | |
3955 | int call_seen; | |
3956 | rtx loop_start; | |
3957 | { | |
3958 | if (CONSTANT_P (x)) | |
3959 | return 1; | |
3960 | ||
3961 | /* Only consider pseudos we know about initialized in insns whose luids | |
3962 | we know. */ | |
3963 | if (GET_CODE (x) != REG | |
3964 | || REGNO (x) >= max_reg_before_loop) | |
3965 | return 0; | |
3966 | ||
3967 | /* Don't use call-clobbered registers across a call which clobbers it. On | |
3968 | some machines, don't use any hard registers at all. */ | |
3969 | if (REGNO (x) < FIRST_PSEUDO_REGISTER | |
3970 | #ifndef SMALL_REGISTER_CLASSES | |
3971 | && call_used_regs[REGNO (x)] && call_seen | |
3972 | #endif | |
3973 | ) | |
3974 | return 0; | |
3975 | ||
3976 | /* Don't use registers that have been clobbered before the start of the | |
3977 | loop. */ | |
3978 | if (reg_set_between_p (x, insn, loop_start)) | |
3979 | return 0; | |
3980 | ||
3981 | return 1; | |
3982 | } | |
3983 | \f | |
3984 | /* Scan X for memory refs and check each memory address | |
3985 | as a possible giv. INSN is the insn whose pattern X comes from. | |
3986 | NOT_EVERY_ITERATION is 1 if the insn might not be executed during | |
3987 | every loop iteration. */ | |
3988 | ||
3989 | static void | |
3990 | find_mem_givs (x, insn, not_every_iteration, loop_start, loop_end) | |
3991 | rtx x; | |
3992 | rtx insn; | |
3993 | int not_every_iteration; | |
3994 | rtx loop_start, loop_end; | |
3995 | { | |
3996 | register int i, j; | |
3997 | register enum rtx_code code; | |
3998 | register char *fmt; | |
3999 | ||
4000 | if (x == 0) | |
4001 | return; | |
4002 | ||
4003 | code = GET_CODE (x); | |
4004 | switch (code) | |
4005 | { | |
4006 | case REG: | |
4007 | case CONST_INT: | |
4008 | case CONST: | |
4009 | case CONST_DOUBLE: | |
4010 | case SYMBOL_REF: | |
4011 | case LABEL_REF: | |
4012 | case PC: | |
4013 | case CC0: | |
4014 | case ADDR_VEC: | |
4015 | case ADDR_DIFF_VEC: | |
4016 | case USE: | |
4017 | case CLOBBER: | |
4018 | return; | |
4019 | ||
4020 | case MEM: | |
4021 | { | |
4022 | rtx src_reg; | |
4023 | rtx add_val; | |
4024 | rtx mult_val; | |
4025 | int benefit; | |
4026 | ||
4027 | benefit = general_induction_var (XEXP (x, 0), | |
4028 | &src_reg, &add_val, &mult_val); | |
4029 | ||
4030 | /* Don't make a DEST_ADDR giv with mult_val == 1 && add_val == 0. | |
4031 | Such a giv isn't useful. */ | |
4032 | if (benefit > 0 && (mult_val != const1_rtx || add_val != const0_rtx)) | |
4033 | { | |
4034 | /* Found one; record it. */ | |
4035 | struct induction *v | |
4036 | = (struct induction *) oballoc (sizeof (struct induction)); | |
4037 | ||
4038 | record_giv (v, insn, src_reg, addr_placeholder, mult_val, | |
4039 | add_val, benefit, DEST_ADDR, not_every_iteration, | |
4040 | &XEXP (x, 0), loop_start, loop_end); | |
4041 | ||
4042 | v->mem_mode = GET_MODE (x); | |
4043 | } | |
4044 | return; | |
4045 | } | |
4046 | } | |
4047 | ||
4048 | /* Recursively scan the subexpressions for other mem refs. */ | |
4049 | ||
4050 | fmt = GET_RTX_FORMAT (code); | |
4051 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
4052 | if (fmt[i] == 'e') | |
4053 | find_mem_givs (XEXP (x, i), insn, not_every_iteration, loop_start, | |
4054 | loop_end); | |
4055 | else if (fmt[i] == 'E') | |
4056 | for (j = 0; j < XVECLEN (x, i); j++) | |
4057 | find_mem_givs (XVECEXP (x, i, j), insn, not_every_iteration, | |
4058 | loop_start, loop_end); | |
4059 | } | |
4060 | \f | |
4061 | /* Fill in the data about one biv update. | |
4062 | V is the `struct induction' in which we record the biv. (It is | |
4063 | allocated by the caller, with alloca.) | |
4064 | INSN is the insn that sets it. | |
4065 | DEST_REG is the biv's reg. | |
4066 | ||
4067 | MULT_VAL is const1_rtx if the biv is being incremented here, in which case | |
4068 | INC_VAL is the increment. Otherwise, MULT_VAL is const0_rtx and the biv is | |
4069 | being set to INC_VAL. | |
4070 | ||
4071 | NOT_EVERY_ITERATION is nonzero if this biv update is not know to be | |
4072 | executed every iteration; MAYBE_MULTIPLE is nonzero if this biv update | |
4073 | can be executed more than once per iteration. If MAYBE_MULTIPLE | |
4074 | and NOT_EVERY_ITERATION are both zero, we know that the biv update is | |
4075 | executed exactly once per iteration. */ | |
4076 | ||
4077 | static void | |
4078 | record_biv (v, insn, dest_reg, inc_val, mult_val, | |
4079 | not_every_iteration, maybe_multiple) | |
4080 | struct induction *v; | |
4081 | rtx insn; | |
4082 | rtx dest_reg; | |
4083 | rtx inc_val; | |
4084 | rtx mult_val; | |
4085 | int not_every_iteration; | |
4086 | int maybe_multiple; | |
4087 | { | |
4088 | struct iv_class *bl; | |
4089 | ||
4090 | v->insn = insn; | |
4091 | v->src_reg = dest_reg; | |
4092 | v->dest_reg = dest_reg; | |
4093 | v->mult_val = mult_val; | |
4094 | v->add_val = inc_val; | |
4095 | v->mode = GET_MODE (dest_reg); | |
4096 | v->always_computable = ! not_every_iteration; | |
4097 | v->maybe_multiple = maybe_multiple; | |
4098 | ||
4099 | /* Add this to the reg's iv_class, creating a class | |
4100 | if this is the first incrementation of the reg. */ | |
4101 | ||
4102 | bl = reg_biv_class[REGNO (dest_reg)]; | |
4103 | if (bl == 0) | |
4104 | { | |
4105 | /* Create and initialize new iv_class. */ | |
4106 | ||
4107 | bl = (struct iv_class *) oballoc (sizeof (struct iv_class)); | |
4108 | ||
4109 | bl->regno = REGNO (dest_reg); | |
4110 | bl->biv = 0; | |
4111 | bl->giv = 0; | |
4112 | bl->biv_count = 0; | |
4113 | bl->giv_count = 0; | |
4114 | ||
4115 | /* Set initial value to the reg itself. */ | |
4116 | bl->initial_value = dest_reg; | |
4117 | /* We haven't seen the initializing insn yet */ | |
4118 | bl->init_insn = 0; | |
4119 | bl->init_set = 0; | |
4120 | bl->initial_test = 0; | |
4121 | bl->incremented = 0; | |
4122 | bl->eliminable = 0; | |
4123 | bl->nonneg = 0; | |
4124 | bl->reversed = 0; | |
4125 | bl->total_benefit = 0; | |
4126 | ||
4127 | /* Add this class to loop_iv_list. */ | |
4128 | bl->next = loop_iv_list; | |
4129 | loop_iv_list = bl; | |
4130 | ||
4131 | /* Put it in the array of biv register classes. */ | |
4132 | reg_biv_class[REGNO (dest_reg)] = bl; | |
4133 | } | |
4134 | ||
4135 | /* Update IV_CLASS entry for this biv. */ | |
4136 | v->next_iv = bl->biv; | |
4137 | bl->biv = v; | |
4138 | bl->biv_count++; | |
4139 | if (mult_val == const1_rtx) | |
4140 | bl->incremented = 1; | |
4141 | ||
4142 | if (loop_dump_stream) | |
4143 | { | |
4144 | fprintf (loop_dump_stream, | |
4145 | "Insn %d: possible biv, reg %d,", | |
4146 | INSN_UID (insn), REGNO (dest_reg)); | |
4147 | if (GET_CODE (inc_val) == CONST_INT) | |
4148 | fprintf (loop_dump_stream, " const = %d\n", | |
4149 | INTVAL (inc_val)); | |
4150 | else | |
4151 | { | |
4152 | fprintf (loop_dump_stream, " const = "); | |
4153 | print_rtl (loop_dump_stream, inc_val); | |
4154 | fprintf (loop_dump_stream, "\n"); | |
4155 | } | |
4156 | } | |
4157 | } | |
4158 | \f | |
4159 | /* Fill in the data about one giv. | |
4160 | V is the `struct induction' in which we record the giv. (It is | |
4161 | allocated by the caller, with alloca.) | |
4162 | INSN is the insn that sets it. | |
4163 | BENEFIT estimates the savings from deleting this insn. | |
4164 | TYPE is DEST_REG or DEST_ADDR; it says whether the giv is computed | |
4165 | into a register or is used as a memory address. | |
4166 | ||
4167 | SRC_REG is the biv reg which the giv is computed from. | |
4168 | DEST_REG is the giv's reg (if the giv is stored in a reg). | |
4169 | MULT_VAL and ADD_VAL are the coefficients used to compute the giv. | |
4170 | LOCATION points to the place where this giv's value appears in INSN. */ | |
4171 | ||
4172 | static void | |
4173 | record_giv (v, insn, src_reg, dest_reg, mult_val, add_val, benefit, | |
4174 | type, not_every_iteration, location, loop_start, loop_end) | |
4175 | struct induction *v; | |
4176 | rtx insn; | |
4177 | rtx src_reg; | |
4178 | rtx dest_reg; | |
4179 | rtx mult_val, add_val; | |
4180 | int benefit; | |
4181 | enum g_types type; | |
4182 | int not_every_iteration; | |
4183 | rtx *location; | |
4184 | rtx loop_start, loop_end; | |
4185 | { | |
4186 | struct induction *b; | |
4187 | struct iv_class *bl; | |
4188 | rtx set = single_set (insn); | |
4189 | rtx p; | |
4190 | ||
4191 | v->insn = insn; | |
4192 | v->src_reg = src_reg; | |
4193 | v->giv_type = type; | |
4194 | v->dest_reg = dest_reg; | |
4195 | v->mult_val = mult_val; | |
4196 | v->add_val = add_val; | |
4197 | v->benefit = benefit; | |
4198 | v->location = location; | |
4199 | v->cant_derive = 0; | |
4200 | v->combined_with = 0; | |
4201 | v->maybe_multiple = 0; | |
4202 | v->maybe_dead = 0; | |
4203 | v->derive_adjustment = 0; | |
4204 | v->same = 0; | |
4205 | v->ignore = 0; | |
4206 | v->new_reg = 0; | |
4207 | v->final_value = 0; | |
4208 | ||
4209 | /* The v->always_computable field is used in update_giv_derive, to | |
4210 | determine whether a giv can be used to derive another giv. For a | |
4211 | DEST_REG giv, INSN computes a new value for the giv, so its value | |
4212 | isn't computable if INSN insn't executed every iteration. | |
4213 | However, for a DEST_ADDR giv, INSN merely uses the value of the giv; | |
4214 | it does not compute a new value. Hence the value is always computable | |
4215 | regardless of whether INSN is executed each iteration. */ | |
4216 | ||
4217 | if (type == DEST_ADDR) | |
4218 | v->always_computable = 1; | |
4219 | else | |
4220 | v->always_computable = ! not_every_iteration; | |
4221 | ||
4222 | if (type == DEST_ADDR) | |
4223 | { | |
4224 | v->mode = GET_MODE (*location); | |
4225 | v->lifetime = 1; | |
4226 | v->times_used = 1; | |
4227 | } | |
4228 | else /* type == DEST_REG */ | |
4229 | { | |
4230 | v->mode = GET_MODE (SET_DEST (set)); | |
4231 | ||
4232 | v->lifetime = (uid_luid[regno_last_uid[REGNO (dest_reg)]] | |
4233 | - uid_luid[regno_first_uid[REGNO (dest_reg)]]); | |
4234 | ||
4235 | v->times_used = n_times_used[REGNO (dest_reg)]; | |
4236 | ||
4237 | /* If the lifetime is zero, it means that this register is | |
4238 | really a dead store. So mark this as a giv that can be | |
4239 | ignored. This will not prevent the biv from being eliminated. */ | |
4240 | if (v->lifetime == 0) | |
4241 | v->ignore = 1; | |
4242 | ||
4243 | reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT; | |
4244 | reg_iv_info[REGNO (dest_reg)] = v; | |
4245 | } | |
4246 | ||
4247 | /* Add the giv to the class of givs computed from one biv. */ | |
4248 | ||
4249 | bl = reg_biv_class[REGNO (src_reg)]; | |
4250 | if (bl) | |
4251 | { | |
4252 | v->next_iv = bl->giv; | |
4253 | bl->giv = v; | |
4254 | /* Don't count DEST_ADDR. This is supposed to count the number of | |
4255 | insns that calculate givs. */ | |
4256 | if (type == DEST_REG) | |
4257 | bl->giv_count++; | |
4258 | bl->total_benefit += benefit; | |
4259 | } | |
4260 | else | |
4261 | /* Fatal error, biv missing for this giv? */ | |
4262 | abort (); | |
4263 | ||
4264 | if (type == DEST_ADDR) | |
4265 | v->replaceable = 1; | |
4266 | else | |
4267 | { | |
4268 | /* The giv can be replaced outright by the reduced register only if all | |
4269 | of the following conditions are true: | |
4270 | - the insn that sets the giv is always executed on any iteration | |
4271 | on which the giv is used at all | |
4272 | (there are two ways to deduce this: | |
4273 | either the insn is executed on every iteration, | |
4274 | or all uses follow that insn in the same basic block), | |
4275 | - the giv is not used outside the loop | |
4276 | - no assignments to the biv occur during the giv's lifetime. */ | |
4277 | ||
4278 | if (regno_first_uid[REGNO (dest_reg)] == INSN_UID (insn) | |
4279 | /* Previous line always fails if INSN was moved by loop opt. */ | |
4280 | && uid_luid[regno_last_uid[REGNO (dest_reg)]] < INSN_LUID (loop_end) | |
4281 | && (! not_every_iteration | |
4282 | || last_use_this_basic_block (dest_reg, insn))) | |
4283 | { | |
4284 | /* Now check that there are no assignments to the biv within the | |
4285 | giv's lifetime. This requires two separate checks. */ | |
4286 | ||
4287 | /* Check each biv update, and fail if any are between the first | |
4288 | and last use of the giv. | |
4289 | ||
4290 | If this loop contains an inner loop that was unrolled, then | |
4291 | the insn modifying the biv may have been emitted by the loop | |
4292 | unrolling code, and hence does not have a valid luid. Just | |
4293 | mark the biv as not replaceable in this case. It is not very | |
4294 | useful as a biv, because it is used in two different loops. | |
4295 | It is very unlikely that we would be able to optimize the giv | |
4296 | using this biv anyways. */ | |
4297 | ||
4298 | v->replaceable = 1; | |
4299 | for (b = bl->biv; b; b = b->next_iv) | |
4300 | { | |
4301 | if (INSN_UID (b->insn) >= max_uid_for_loop | |
4302 | || ((uid_luid[INSN_UID (b->insn)] | |
4303 | >= uid_luid[regno_first_uid[REGNO (dest_reg)]]) | |
4304 | && (uid_luid[INSN_UID (b->insn)] | |
4305 | <= uid_luid[regno_last_uid[REGNO (dest_reg)]]))) | |
4306 | { | |
4307 | v->replaceable = 0; | |
4308 | v->not_replaceable = 1; | |
4309 | break; | |
4310 | } | |
4311 | } | |
4312 | ||
4313 | /* Check each insn between the first and last use of the giv, | |
4314 | and fail if any of them are branches that jump to a named label | |
4315 | outside this range, but still inside the loop. This catches | |
4316 | cases of spaghetti code where the execution order of insns | |
4317 | is not linear, and hence the above test fails. For example, | |
4318 | in the following code, j is not replaceable: | |
4319 | for (i = 0; i < 100; ) { | |
4320 | L0: j = 4*i; goto L1; | |
4321 | L2: k = j; goto L3; | |
4322 | L1: i++; goto L2; | |
4323 | L3: ; } | |
4324 | printf ("k = %d\n", k); } | |
4325 | This test is conservative, but this test succeeds rarely enough | |
4326 | that it isn't a problem. See also check_final_value below. */ | |
4327 | ||
4328 | if (v->replaceable) | |
4329 | for (p = insn; | |
4330 | INSN_UID (p) >= max_uid_for_loop | |
4331 | || INSN_LUID (p) < uid_luid[regno_last_uid[REGNO (dest_reg)]]; | |
4332 | p = NEXT_INSN (p)) | |
4333 | { | |
4334 | if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) | |
4335 | && LABEL_NAME (JUMP_LABEL (p)) | |
4336 | && ((INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start) | |
4337 | && (INSN_LUID (JUMP_LABEL (p)) | |
4338 | < uid_luid[regno_first_uid[REGNO (dest_reg)]])) | |
4339 | || (INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end) | |
4340 | && (INSN_LUID (JUMP_LABEL (p)) | |
4341 | > uid_luid[regno_last_uid[REGNO (dest_reg)]])))) | |
4342 | { | |
4343 | v->replaceable = 0; | |
4344 | v->not_replaceable = 1; | |
4345 | ||
4346 | if (loop_dump_stream) | |
4347 | fprintf (loop_dump_stream, | |
4348 | "Found branch outside giv lifetime.\n"); | |
4349 | ||
4350 | break; | |
4351 | } | |
4352 | } | |
4353 | } | |
4354 | else | |
4355 | { | |
4356 | /* May still be replaceable, we don't have enough info here to | |
4357 | decide. */ | |
4358 | v->replaceable = 0; | |
4359 | v->not_replaceable = 0; | |
4360 | } | |
4361 | } | |
4362 | ||
4363 | if (loop_dump_stream) | |
4364 | { | |
4365 | if (type == DEST_REG) | |
4366 | fprintf (loop_dump_stream, "Insn %d: giv reg %d", | |
4367 | INSN_UID (insn), REGNO (dest_reg)); | |
4368 | else | |
4369 | fprintf (loop_dump_stream, "Insn %d: dest address", | |
4370 | INSN_UID (insn)); | |
4371 | ||
4372 | fprintf (loop_dump_stream, " src reg %d benefit %d", | |
4373 | REGNO (src_reg), v->benefit); | |
4374 | fprintf (loop_dump_stream, " used %d lifetime %d", | |
4375 | v->times_used, v->lifetime); | |
4376 | ||
4377 | if (v->replaceable) | |
4378 | fprintf (loop_dump_stream, " replaceable"); | |
4379 | ||
4380 | if (GET_CODE (mult_val) == CONST_INT) | |
4381 | fprintf (loop_dump_stream, " mult %d", | |
4382 | INTVAL (mult_val)); | |
4383 | else | |
4384 | { | |
4385 | fprintf (loop_dump_stream, " mult "); | |
4386 | print_rtl (loop_dump_stream, mult_val); | |
4387 | } | |
4388 | ||
4389 | if (GET_CODE (add_val) == CONST_INT) | |
4390 | fprintf (loop_dump_stream, " add %d", | |
4391 | INTVAL (add_val)); | |
4392 | else | |
4393 | { | |
4394 | fprintf (loop_dump_stream, " add "); | |
4395 | print_rtl (loop_dump_stream, add_val); | |
4396 | } | |
4397 | } | |
4398 | ||
4399 | if (loop_dump_stream) | |
4400 | fprintf (loop_dump_stream, "\n"); | |
4401 | ||
4402 | } | |
4403 | ||
4404 | ||
4405 | /* All this does is determine whether a giv can be made replaceable because | |
4406 | its final value can be calculated. This code can not be part of record_giv | |
4407 | above, because final_giv_value requires that the number of loop iterations | |
4408 | be known, and that can not be accurately calculated until after all givs | |
4409 | have been identified. */ | |
4410 | ||
4411 | static void | |
4412 | check_final_value (v, loop_start, loop_end) | |
4413 | struct induction *v; | |
4414 | rtx loop_start, loop_end; | |
4415 | { | |
4416 | struct iv_class *bl; | |
4417 | rtx final_value = 0; | |
4418 | rtx tem; | |
4419 | ||
4420 | bl = reg_biv_class[REGNO (v->src_reg)]; | |
4421 | ||
4422 | /* DEST_ADDR givs will never reach here, because they are always marked | |
4423 | replaceable above in record_giv. */ | |
4424 | ||
4425 | /* The giv can be replaced outright by the reduced register only if all | |
4426 | of the following conditions are true: | |
4427 | - the insn that sets the giv is always executed on any iteration | |
4428 | on which the giv is used at all | |
4429 | (there are two ways to deduce this: | |
4430 | either the insn is executed on every iteration, | |
4431 | or all uses follow that insn in the same basic block), | |
4432 | - its final value can be calculated (this condition is different | |
4433 | than the one above in record_giv) | |
4434 | - no assignments to the biv occur during the giv's lifetime. */ | |
4435 | ||
4436 | #if 0 | |
4437 | /* This is only called now when replaceable is known to be false. */ | |
4438 | /* Clear replaceable, so that it won't confuse final_giv_value. */ | |
4439 | v->replaceable = 0; | |
4440 | #endif | |
4441 | ||
4442 | if ((final_value = final_giv_value (v, loop_start, loop_end)) | |
4443 | && (v->always_computable || last_use_this_basic_block (v->dest_reg, v->insn))) | |
4444 | { | |
4445 | int biv_increment_seen = 0; | |
4446 | rtx p = v->insn; | |
4447 | rtx last_giv_use; | |
4448 | ||
4449 | v->replaceable = 1; | |
4450 | ||
4451 | /* When trying to determine whether or not a biv increment occurs | |
4452 | during the lifetime of the giv, we can ignore uses of the variable | |
4453 | outside the loop because final_value is true. Hence we can not | |
4454 | use regno_last_uid and regno_first_uid as above in record_giv. */ | |
4455 | ||
4456 | /* Search the loop to determine whether any assignments to the | |
4457 | biv occur during the giv's lifetime. Start with the insn | |
4458 | that sets the giv, and search around the loop until we come | |
4459 | back to that insn again. | |
4460 | ||
4461 | Also fail if there is a jump within the giv's lifetime that jumps | |
4462 | to somewhere outside the lifetime but still within the loop. This | |
4463 | catches spaghetti code where the execution order is not linear, and | |
4464 | hence the above test fails. Here we assume that the giv lifetime | |
4465 | does not extend from one iteration of the loop to the next, so as | |
4466 | to make the test easier. Since the lifetime isn't known yet, | |
4467 | this requires two loops. See also record_giv above. */ | |
4468 | ||
4469 | last_giv_use = v->insn; | |
4470 | ||
4471 | while (1) | |
4472 | { | |
4473 | p = NEXT_INSN (p); | |
4474 | if (p == loop_end) | |
4475 | p = NEXT_INSN (loop_start); | |
4476 | if (p == v->insn) | |
4477 | break; | |
4478 | ||
4479 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
4480 | || GET_CODE (p) == CALL_INSN) | |
4481 | { | |
4482 | if (biv_increment_seen) | |
4483 | { | |
4484 | if (reg_mentioned_p (v->dest_reg, PATTERN (p))) | |
4485 | { | |
4486 | v->replaceable = 0; | |
4487 | v->not_replaceable = 1; | |
4488 | break; | |
4489 | } | |
4490 | } | |
4491 | else if (GET_CODE (PATTERN (p)) == SET | |
4492 | && SET_DEST (PATTERN (p)) == v->src_reg) | |
4493 | biv_increment_seen = 1; | |
4494 | else if (reg_mentioned_p (v->dest_reg, PATTERN (p))) | |
4495 | last_giv_use = p; | |
4496 | } | |
4497 | } | |
4498 | ||
4499 | /* Now that the lifetime of the giv is known, check for branches | |
4500 | from within the lifetime to outside the lifetime if it is still | |
4501 | replaceable. */ | |
4502 | ||
4503 | if (v->replaceable) | |
4504 | { | |
4505 | p = v->insn; | |
4506 | while (1) | |
4507 | { | |
4508 | p = NEXT_INSN (p); | |
4509 | if (p == loop_end) | |
4510 | p = NEXT_INSN (loop_start); | |
4511 | if (p == last_giv_use) | |
4512 | break; | |
4513 | ||
4514 | if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) | |
4515 | && LABEL_NAME (JUMP_LABEL (p)) | |
4516 | && ((INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (v->insn) | |
4517 | && INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start)) | |
4518 | || (INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (last_giv_use) | |
4519 | && INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end)))) | |
4520 | { | |
4521 | v->replaceable = 0; | |
4522 | v->not_replaceable = 1; | |
4523 | ||
4524 | if (loop_dump_stream) | |
4525 | fprintf (loop_dump_stream, | |
4526 | "Found branch outside giv lifetime.\n"); | |
4527 | ||
4528 | break; | |
4529 | } | |
4530 | } | |
4531 | } | |
4532 | ||
4533 | /* If it is replaceable, then save the final value. */ | |
4534 | if (v->replaceable) | |
4535 | v->final_value = final_value; | |
4536 | } | |
4537 | ||
4538 | if (loop_dump_stream && v->replaceable) | |
4539 | fprintf (loop_dump_stream, "Insn %d: giv reg %d final_value replaceable\n", | |
4540 | INSN_UID (v->insn), REGNO (v->dest_reg)); | |
4541 | } | |
4542 | \f | |
4543 | /* Update the status of whether a giv can derive other givs. | |
4544 | ||
4545 | We need to do something special if there is or may be an update to the biv | |
4546 | between the time the giv is defined and the time it is used to derive | |
4547 | another giv. | |
4548 | ||
4549 | In addition, a giv that is only conditionally set is not allowed to | |
4550 | derive another giv once a label has been passed. | |
4551 | ||
4552 | The cases we look at are when a label or an update to a biv is passed. */ | |
4553 | ||
4554 | static void | |
4555 | update_giv_derive (p) | |
4556 | rtx p; | |
4557 | { | |
4558 | struct iv_class *bl; | |
4559 | struct induction *biv, *giv; | |
4560 | rtx tem; | |
4561 | int dummy; | |
4562 | ||
4563 | /* Search all IV classes, then all bivs, and finally all givs. | |
4564 | ||
4565 | There are three cases we are concerned with. First we have the situation | |
4566 | of a giv that is only updated conditionally. In that case, it may not | |
4567 | derive any givs after a label is passed. | |
4568 | ||
4569 | The second case is when a biv update occurs, or may occur, after the | |
4570 | definition of a giv. For certain biv updates (see below) that are | |
4571 | known to occur between the giv definition and use, we can adjust the | |
4572 | giv definition. For others, or when the biv update is conditional, | |
4573 | we must prevent the giv from deriving any other givs. There are two | |
4574 | sub-cases within this case. | |
4575 | ||
4576 | If this is a label, we are concerned with any biv update that is done | |
4577 | conditionally, since it may be done after the giv is defined followed by | |
4578 | a branch here (actually, we need to pass both a jump and a label, but | |
4579 | this extra tracking doesn't seem worth it). | |
4580 | ||
4581 | If this is a jump, we are concerned about any biv update that may be | |
4582 | executed multiple times. We are actually only concerned about | |
4583 | backward jumps, but it is probably not worth performing the test | |
4584 | on the jump again here. | |
4585 | ||
4586 | If this is a biv update, we must adjust the giv status to show that a | |
4587 | subsequent biv update was performed. If this adjustment cannot be done, | |
4588 | the giv cannot derive further givs. */ | |
4589 | ||
4590 | for (bl = loop_iv_list; bl; bl = bl->next) | |
4591 | for (biv = bl->biv; biv; biv = biv->next_iv) | |
4592 | if (GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN | |
4593 | || biv->insn == p) | |
4594 | { | |
4595 | for (giv = bl->giv; giv; giv = giv->next_iv) | |
4596 | { | |
4597 | /* If cant_derive is already true, there is no point in | |
4598 | checking all of these conditions again. */ | |
4599 | if (giv->cant_derive) | |
4600 | continue; | |
4601 | ||
4602 | /* If this giv is conditionally set and we have passed a label, | |
4603 | it cannot derive anything. */ | |
4604 | if (GET_CODE (p) == CODE_LABEL && ! giv->always_computable) | |
4605 | giv->cant_derive = 1; | |
4606 | ||
4607 | /* Skip givs that have mult_val == 0, since | |
4608 | they are really invariants. Also skip those that are | |
4609 | replaceable, since we know their lifetime doesn't contain | |
4610 | any biv update. */ | |
4611 | else if (giv->mult_val == const0_rtx || giv->replaceable) | |
4612 | continue; | |
4613 | ||
4614 | /* The only way we can allow this giv to derive another | |
4615 | is if this is a biv increment and we can form the product | |
4616 | of biv->add_val and giv->mult_val. In this case, we will | |
4617 | be able to compute a compensation. */ | |
4618 | else if (biv->insn == p) | |
4619 | { | |
4620 | tem = 0; | |
4621 | ||
4622 | if (biv->mult_val == const1_rtx) | |
4623 | tem = simplify_giv_expr (gen_rtx (MULT, giv->mode, | |
4624 | biv->add_val, | |
4625 | giv->mult_val), | |
4626 | &dummy); | |
4627 | ||
4628 | if (tem && giv->derive_adjustment) | |
4629 | tem = simplify_giv_expr (gen_rtx (PLUS, giv->mode, tem, | |
4630 | giv->derive_adjustment), | |
4631 | &dummy); | |
4632 | if (tem) | |
4633 | giv->derive_adjustment = tem; | |
4634 | else | |
4635 | giv->cant_derive = 1; | |
4636 | } | |
4637 | else if ((GET_CODE (p) == CODE_LABEL && ! biv->always_computable) | |
4638 | || (GET_CODE (p) == JUMP_INSN && biv->maybe_multiple)) | |
4639 | giv->cant_derive = 1; | |
4640 | } | |
4641 | } | |
4642 | } | |
4643 | \f | |
4644 | /* Check whether an insn is an increment legitimate for a basic induction var. | |
4645 | X is the source of insn P. | |
4646 | DEST_REG is the putative biv, also the destination of the insn. | |
4647 | We accept patterns of these forms: | |
4648 | REG = REG + INVARIANT (includes REG = REG - CONSTANT) | |
4649 | REG = INVARIANT + REG | |
4650 | ||
4651 | If X is suitable, we return 1, set *MULT_VAL to CONST1_RTX, | |
4652 | and store the additive term into *INC_VAL. | |
4653 | ||
4654 | If X is an assignment of an invariant into DEST_REG, we set | |
4655 | *MULT_VAL to CONST0_RTX, and store the invariant into *INC_VAL. | |
4656 | ||
4657 | We also want to detect a BIV when it corresponds to a variable | |
4658 | whose mode was promoted via PROMOTED_MODE. In that case, an increment | |
4659 | of the variable may be a PLUS that adds a SUBREG of that variable to | |
4660 | an invariant and then sign- or zero-extends the result of the PLUS | |
4661 | into the variable. | |
4662 | ||
4663 | Most GIVs in such cases will be in the promoted mode, since that is the | |
4664 | probably the natural computation mode (and almost certainly the mode | |
4665 | used for addresses) on the machine. So we view the pseudo-reg containing | |
4666 | the variable as the BIV, as if it were simply incremented. | |
4667 | ||
4668 | Note that treating the entire pseudo as a BIV will result in making | |
4669 | simple increments to any GIVs based on it. However, if the variable | |
4670 | overflows in its declared mode but not its promoted mode, the result will | |
4671 | be incorrect. This is acceptable if the variable is signed, since | |
4672 | overflows in such cases are undefined, but not if it is unsigned, since | |
4673 | those overflows are defined. So we only check for SIGN_EXTEND and | |
4674 | not ZERO_EXTEND. | |
4675 | ||
4676 | If we cannot find a biv, we return 0. */ | |
4677 | ||
4678 | static int | |
4679 | basic_induction_var (x, dest_reg, p, inc_val, mult_val) | |
4680 | register rtx x; | |
4681 | rtx p; | |
4682 | rtx dest_reg; | |
4683 | rtx *inc_val; | |
4684 | rtx *mult_val; | |
4685 | { | |
4686 | register enum rtx_code code; | |
4687 | rtx arg; | |
4688 | rtx insn, set = 0; | |
4689 | ||
4690 | code = GET_CODE (x); | |
4691 | switch (code) | |
4692 | { | |
4693 | case PLUS: | |
4694 | if (XEXP (x, 0) == dest_reg | |
4695 | || (GET_CODE (XEXP (x, 0)) == SUBREG | |
4696 | && SUBREG_PROMOTED_VAR_P (XEXP (x, 0)) | |
4697 | && SUBREG_REG (XEXP (x, 0)) == dest_reg)) | |
4698 | arg = XEXP (x, 1); | |
4699 | else if (XEXP (x, 1) == dest_reg | |
4700 | || (GET_CODE (XEXP (x, 1)) == SUBREG | |
4701 | && SUBREG_PROMOTED_VAR_P (XEXP (x, 1)) | |
4702 | && SUBREG_REG (XEXP (x, 1)) == dest_reg)) | |
4703 | arg = XEXP (x, 0); | |
4704 | else | |
4705 | return 0; | |
4706 | ||
4707 | if (invariant_p (arg) != 1) | |
4708 | return 0; | |
4709 | ||
4710 | *inc_val = convert_to_mode (GET_MODE (dest_reg), arg, 0);; | |
4711 | *mult_val = const1_rtx; | |
4712 | return 1; | |
4713 | ||
4714 | case SUBREG: | |
4715 | /* If this is a SUBREG for a promoted variable, check the inner | |
4716 | value. */ | |
4717 | if (SUBREG_PROMOTED_VAR_P (x)) | |
4718 | return basic_induction_var (SUBREG_REG (x), dest_reg, p, | |
4719 | inc_val, mult_val); | |
4720 | ||
4721 | case REG: | |
4722 | /* If this register is assigned in the previous insn, look at its | |
4723 | source, but don't go outside the loop or past a label. */ | |
4724 | ||
4725 | for (insn = PREV_INSN (p); | |
4726 | (insn && GET_CODE (insn) == NOTE | |
4727 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG); | |
4728 | insn = PREV_INSN (insn)) | |
4729 | ; | |
4730 | ||
4731 | if (insn) | |
4732 | set = single_set (insn); | |
4733 | ||
4734 | if (set != 0 && SET_DEST (set) == x) | |
4735 | return basic_induction_var (SET_SRC (set), dest_reg, insn, | |
4736 | inc_val, mult_val); | |
4737 | /* ... fall through ... */ | |
4738 | ||
4739 | /* Can accept constant setting of biv only when inside inner most loop. | |
4740 | Otherwise, a biv of an inner loop may be incorrectly recognized | |
4741 | as a biv of the outer loop, | |
4742 | causing code to be moved INTO the inner loop. */ | |
4743 | case MEM: | |
4744 | if (invariant_p (x) != 1) | |
4745 | return 0; | |
4746 | case CONST_INT: | |
4747 | case SYMBOL_REF: | |
4748 | case CONST: | |
4749 | if (loops_enclosed == 1) | |
4750 | { | |
4751 | *inc_val = convert_to_mode (GET_MODE (dest_reg), x, 0);; | |
4752 | *mult_val = const0_rtx; | |
4753 | return 1; | |
4754 | } | |
4755 | else | |
4756 | return 0; | |
4757 | ||
4758 | case SIGN_EXTEND: | |
4759 | return basic_induction_var (XEXP (x, 0), dest_reg, p, | |
4760 | inc_val, mult_val); | |
4761 | case ASHIFTRT: | |
4762 | /* Similar, since this can be a sign extension. */ | |
4763 | for (insn = PREV_INSN (p); | |
4764 | (insn && GET_CODE (insn) == NOTE | |
4765 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG); | |
4766 | insn = PREV_INSN (insn)) | |
4767 | ; | |
4768 | ||
4769 | if (insn) | |
4770 | set = single_set (insn); | |
4771 | ||
4772 | if (set && SET_DEST (set) == XEXP (x, 0) | |
4773 | && GET_CODE (XEXP (x, 1)) == CONST_INT | |
4774 | && INTVAL (XEXP (x, 1)) >= 0 | |
4775 | && GET_CODE (SET_SRC (set)) == ASHIFT | |
4776 | && XEXP (x, 1) == XEXP (SET_SRC (set), 1)) | |
4777 | return basic_induction_var (XEXP (SET_SRC (set), 0), dest_reg, insn, | |
4778 | inc_val, mult_val); | |
4779 | return 0; | |
4780 | ||
4781 | default: | |
4782 | return 0; | |
4783 | } | |
4784 | } | |
4785 | \f | |
4786 | /* A general induction variable (giv) is any quantity that is a linear | |
4787 | function of a basic induction variable, | |
4788 | i.e. giv = biv * mult_val + add_val. | |
4789 | The coefficients can be any loop invariant quantity. | |
4790 | A giv need not be computed directly from the biv; | |
4791 | it can be computed by way of other givs. */ | |
4792 | ||
4793 | /* Determine whether X computes a giv. | |
4794 | If it does, return a nonzero value | |
4795 | which is the benefit from eliminating the computation of X; | |
4796 | set *SRC_REG to the register of the biv that it is computed from; | |
4797 | set *ADD_VAL and *MULT_VAL to the coefficients, | |
4798 | such that the value of X is biv * mult + add; */ | |
4799 | ||
4800 | static int | |
4801 | general_induction_var (x, src_reg, add_val, mult_val) | |
4802 | rtx x; | |
4803 | rtx *src_reg; | |
4804 | rtx *add_val; | |
4805 | rtx *mult_val; | |
4806 | { | |
4807 | rtx orig_x = x; | |
4808 | int benefit = 0; | |
4809 | char *storage; | |
4810 | ||
4811 | /* If this is an invariant, forget it, it isn't a giv. */ | |
4812 | if (invariant_p (x) == 1) | |
4813 | return 0; | |
4814 | ||
4815 | /* See if the expression could be a giv and get its form. | |
4816 | Mark our place on the obstack in case we don't find a giv. */ | |
4817 | storage = (char *) oballoc (0); | |
4818 | x = simplify_giv_expr (x, &benefit); | |
4819 | if (x == 0) | |
4820 | { | |
4821 | obfree (storage); | |
4822 | return 0; | |
4823 | } | |
4824 | ||
4825 | switch (GET_CODE (x)) | |
4826 | { | |
4827 | case USE: | |
4828 | case CONST_INT: | |
4829 | /* Since this is now an invariant and wasn't before, it must be a giv | |
4830 | with MULT_VAL == 0. It doesn't matter which BIV we associate this | |
4831 | with. */ | |
4832 | *src_reg = loop_iv_list->biv->dest_reg; | |
4833 | *mult_val = const0_rtx; | |
4834 | *add_val = x; | |
4835 | break; | |
4836 | ||
4837 | case REG: | |
4838 | /* This is equivalent to a BIV. */ | |
4839 | *src_reg = x; | |
4840 | *mult_val = const1_rtx; | |
4841 | *add_val = const0_rtx; | |
4842 | break; | |
4843 | ||
4844 | case PLUS: | |
4845 | /* Either (plus (biv) (invar)) or | |
4846 | (plus (mult (biv) (invar_1)) (invar_2)). */ | |
4847 | if (GET_CODE (XEXP (x, 0)) == MULT) | |
4848 | { | |
4849 | *src_reg = XEXP (XEXP (x, 0), 0); | |
4850 | *mult_val = XEXP (XEXP (x, 0), 1); | |
4851 | } | |
4852 | else | |
4853 | { | |
4854 | *src_reg = XEXP (x, 0); | |
4855 | *mult_val = const1_rtx; | |
4856 | } | |
4857 | *add_val = XEXP (x, 1); | |
4858 | break; | |
4859 | ||
4860 | case MULT: | |
4861 | /* ADD_VAL is zero. */ | |
4862 | *src_reg = XEXP (x, 0); | |
4863 | *mult_val = XEXP (x, 1); | |
4864 | *add_val = const0_rtx; | |
4865 | break; | |
4866 | ||
4867 | default: | |
4868 | abort (); | |
4869 | } | |
4870 | ||
4871 | /* Remove any enclosing USE from ADD_VAL and MULT_VAL (there will be | |
4872 | unless they are CONST_INT). */ | |
4873 | if (GET_CODE (*add_val) == USE) | |
4874 | *add_val = XEXP (*add_val, 0); | |
4875 | if (GET_CODE (*mult_val) == USE) | |
4876 | *mult_val = XEXP (*mult_val, 0); | |
4877 | ||
4878 | benefit += rtx_cost (orig_x, SET); | |
4879 | ||
4880 | /* Always return some benefit if this is a giv so it will be detected | |
4881 | as such. This allows elimination of bivs that might otherwise | |
4882 | not be eliminated. */ | |
4883 | return benefit == 0 ? 1 : benefit; | |
4884 | } | |
4885 | \f | |
4886 | /* Given an expression, X, try to form it as a linear function of a biv. | |
4887 | We will canonicalize it to be of the form | |
4888 | (plus (mult (BIV) (invar_1)) | |
4889 | (invar_2)) | |
4890 | with possible degeneracies. | |
4891 | ||
4892 | The invariant expressions must each be of a form that can be used as a | |
4893 | machine operand. We surround then with a USE rtx (a hack, but localized | |
4894 | and certainly unambiguous!) if not a CONST_INT for simplicity in this | |
4895 | routine; it is the caller's responsibility to strip them. | |
4896 | ||
4897 | If no such canonicalization is possible (i.e., two biv's are used or an | |
4898 | expression that is neither invariant nor a biv or giv), this routine | |
4899 | returns 0. | |
4900 | ||
4901 | For a non-zero return, the result will have a code of CONST_INT, USE, | |
4902 | REG (for a BIV), PLUS, or MULT. No other codes will occur. | |
4903 | ||
4904 | *BENEFIT will be incremented by the benefit of any sub-giv encountered. */ | |
4905 | ||
4906 | static rtx | |
4907 | simplify_giv_expr (x, benefit) | |
4908 | rtx x; | |
4909 | int *benefit; | |
4910 | { | |
4911 | enum machine_mode mode = GET_MODE (x); | |
4912 | rtx arg0, arg1; | |
4913 | rtx tem; | |
4914 | ||
4915 | /* If this is not an integer mode, or if we cannot do arithmetic in this | |
4916 | mode, this can't be a giv. */ | |
4917 | if (mode != VOIDmode | |
4918 | && (GET_MODE_CLASS (mode) != MODE_INT | |
4919 | || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT)) | |
4920 | return 0; | |
4921 | ||
4922 | switch (GET_CODE (x)) | |
4923 | { | |
4924 | case PLUS: | |
4925 | arg0 = simplify_giv_expr (XEXP (x, 0), benefit); | |
4926 | arg1 = simplify_giv_expr (XEXP (x, 1), benefit); | |
4927 | if (arg0 == 0 || arg1 == 0) | |
4928 | return 0; | |
4929 | ||
4930 | /* Put constant last, CONST_INT last if both constant. */ | |
4931 | if ((GET_CODE (arg0) == USE | |
4932 | || GET_CODE (arg0) == CONST_INT) | |
4933 | && GET_CODE (arg1) != CONST_INT) | |
4934 | tem = arg0, arg0 = arg1, arg1 = tem; | |
4935 | ||
4936 | /* Handle addition of zero, then addition of an invariant. */ | |
4937 | if (arg1 == const0_rtx) | |
4938 | return arg0; | |
4939 | else if (GET_CODE (arg1) == CONST_INT || GET_CODE (arg1) == USE) | |
4940 | switch (GET_CODE (arg0)) | |
4941 | { | |
4942 | case CONST_INT: | |
4943 | case USE: | |
4944 | /* Both invariant. Only valid if sum is machine operand. | |
4945 | First strip off possible USE on first operand. */ | |
4946 | if (GET_CODE (arg0) == USE) | |
4947 | arg0 = XEXP (arg0, 0); | |
4948 | ||
4949 | tem = 0; | |
4950 | if (CONSTANT_P (arg0) && GET_CODE (arg1) == CONST_INT) | |
4951 | { | |
4952 | tem = plus_constant (arg0, INTVAL (arg1)); | |
4953 | if (GET_CODE (tem) != CONST_INT) | |
4954 | tem = gen_rtx (USE, mode, tem); | |
4955 | } | |
4956 | ||
4957 | return tem; | |
4958 | ||
4959 | case REG: | |
4960 | case MULT: | |
4961 | /* biv + invar or mult + invar. Return sum. */ | |
4962 | return gen_rtx (PLUS, mode, arg0, arg1); | |
4963 | ||
4964 | case PLUS: | |
4965 | /* (a + invar_1) + invar_2. Associate. */ | |
4966 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
4967 | XEXP (arg0, 0), | |
4968 | gen_rtx (PLUS, mode, | |
4969 | XEXP (arg0, 1), arg1)), | |
4970 | benefit); | |
4971 | ||
4972 | default: | |
4973 | abort (); | |
4974 | } | |
4975 | ||
4976 | /* Each argument must be either REG, PLUS, or MULT. Convert REG to | |
4977 | MULT to reduce cases. */ | |
4978 | if (GET_CODE (arg0) == REG) | |
4979 | arg0 = gen_rtx (MULT, mode, arg0, const1_rtx); | |
4980 | if (GET_CODE (arg1) == REG) | |
4981 | arg1 = gen_rtx (MULT, mode, arg1, const1_rtx); | |
4982 | ||
4983 | /* Now have PLUS + PLUS, PLUS + MULT, MULT + PLUS, or MULT + MULT. | |
4984 | Put a MULT first, leaving PLUS + PLUS, MULT + PLUS, or MULT + MULT. | |
4985 | Recurse to associate the second PLUS. */ | |
4986 | if (GET_CODE (arg1) == MULT) | |
4987 | tem = arg0, arg0 = arg1, arg1 = tem; | |
4988 | ||
4989 | if (GET_CODE (arg1) == PLUS) | |
4990 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
4991 | gen_rtx (PLUS, mode, | |
4992 | arg0, XEXP (arg1, 0)), | |
4993 | XEXP (arg1, 1)), | |
4994 | benefit); | |
4995 | ||
4996 | /* Now must have MULT + MULT. Distribute if same biv, else not giv. */ | |
4997 | if (GET_CODE (arg0) != MULT || GET_CODE (arg1) != MULT) | |
4998 | abort (); | |
4999 | ||
5000 | if (XEXP (arg0, 0) != XEXP (arg1, 0)) | |
5001 | return 0; | |
5002 | ||
5003 | return simplify_giv_expr (gen_rtx (MULT, mode, | |
5004 | XEXP (arg0, 0), | |
5005 | gen_rtx (PLUS, mode, | |
5006 | XEXP (arg0, 1), | |
5007 | XEXP (arg1, 1))), | |
5008 | benefit); | |
5009 | ||
5010 | case MINUS: | |
5011 | /* Handle "a - b" as "a + b * (-1)". */ | |
5012 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
5013 | XEXP (x, 0), | |
5014 | gen_rtx (MULT, mode, | |
5015 | XEXP (x, 1), constm1_rtx)), | |
5016 | benefit); | |
5017 | ||
5018 | case MULT: | |
5019 | arg0 = simplify_giv_expr (XEXP (x, 0), benefit); | |
5020 | arg1 = simplify_giv_expr (XEXP (x, 1), benefit); | |
5021 | if (arg0 == 0 || arg1 == 0) | |
5022 | return 0; | |
5023 | ||
5024 | /* Put constant last, CONST_INT last if both constant. */ | |
5025 | if ((GET_CODE (arg0) == USE || GET_CODE (arg0) == CONST_INT) | |
5026 | && GET_CODE (arg1) != CONST_INT) | |
5027 | tem = arg0, arg0 = arg1, arg1 = tem; | |
5028 | ||
5029 | /* If second argument is not now constant, not giv. */ | |
5030 | if (GET_CODE (arg1) != USE && GET_CODE (arg1) != CONST_INT) | |
5031 | return 0; | |
5032 | ||
5033 | /* Handle multiply by 0 or 1. */ | |
5034 | if (arg1 == const0_rtx) | |
5035 | return const0_rtx; | |
5036 | ||
5037 | else if (arg1 == const1_rtx) | |
5038 | return arg0; | |
5039 | ||
5040 | switch (GET_CODE (arg0)) | |
5041 | { | |
5042 | case REG: | |
5043 | /* biv * invar. Done. */ | |
5044 | return gen_rtx (MULT, mode, arg0, arg1); | |
5045 | ||
5046 | case CONST_INT: | |
5047 | /* Product of two constants. */ | |
5048 | return GEN_INT (INTVAL (arg0) * INTVAL (arg1)); | |
5049 | ||
5050 | case USE: | |
5051 | /* invar * invar. Not giv. */ | |
5052 | return 0; | |
5053 | ||
5054 | case MULT: | |
5055 | /* (a * invar_1) * invar_2. Associate. */ | |
5056 | return simplify_giv_expr (gen_rtx (MULT, mode, | |
5057 | XEXP (arg0, 0), | |
5058 | gen_rtx (MULT, mode, | |
5059 | XEXP (arg0, 1), arg1)), | |
5060 | benefit); | |
5061 | ||
5062 | case PLUS: | |
5063 | /* (a + invar_1) * invar_2. Distribute. */ | |
5064 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
5065 | gen_rtx (MULT, mode, | |
5066 | XEXP (arg0, 0), arg1), | |
5067 | gen_rtx (MULT, mode, | |
5068 | XEXP (arg0, 1), arg1)), | |
5069 | benefit); | |
5070 | ||
5071 | default: | |
5072 | abort (); | |
5073 | } | |
5074 | ||
5075 | case ASHIFT: | |
5076 | case LSHIFT: | |
5077 | /* Shift by constant is multiply by power of two. */ | |
5078 | if (GET_CODE (XEXP (x, 1)) != CONST_INT) | |
5079 | return 0; | |
5080 | ||
5081 | return simplify_giv_expr (gen_rtx (MULT, mode, | |
5082 | XEXP (x, 0), | |
5083 | GEN_INT ((HOST_WIDE_INT) 1 | |
5084 | << INTVAL (XEXP (x, 1)))), | |
5085 | benefit); | |
5086 | ||
5087 | case NEG: | |
5088 | /* "-a" is "a * (-1)" */ | |
5089 | return simplify_giv_expr (gen_rtx (MULT, mode, XEXP (x, 0), constm1_rtx), | |
5090 | benefit); | |
5091 | ||
5092 | case NOT: | |
5093 | /* "~a" is "-a - 1". Silly, but easy. */ | |
5094 | return simplify_giv_expr (gen_rtx (MINUS, mode, | |
5095 | gen_rtx (NEG, mode, XEXP (x, 0)), | |
5096 | const1_rtx), | |
5097 | benefit); | |
5098 | ||
5099 | case USE: | |
5100 | /* Already in proper form for invariant. */ | |
5101 | return x; | |
5102 | ||
5103 | case REG: | |
5104 | /* If this is a new register, we can't deal with it. */ | |
5105 | if (REGNO (x) >= max_reg_before_loop) | |
5106 | return 0; | |
5107 | ||
5108 | /* Check for biv or giv. */ | |
5109 | switch (reg_iv_type[REGNO (x)]) | |
5110 | { | |
5111 | case BASIC_INDUCT: | |
5112 | return x; | |
5113 | case GENERAL_INDUCT: | |
5114 | { | |
5115 | struct induction *v = reg_iv_info[REGNO (x)]; | |
5116 | ||
5117 | /* Form expression from giv and add benefit. Ensure this giv | |
5118 | can derive another and subtract any needed adjustment if so. */ | |
5119 | *benefit += v->benefit; | |
5120 | if (v->cant_derive) | |
5121 | return 0; | |
5122 | ||
5123 | tem = gen_rtx (PLUS, mode, gen_rtx (MULT, mode, | |
5124 | v->src_reg, v->mult_val), | |
5125 | v->add_val); | |
5126 | if (v->derive_adjustment) | |
5127 | tem = gen_rtx (MINUS, mode, tem, v->derive_adjustment); | |
5128 | return simplify_giv_expr (tem, benefit); | |
5129 | } | |
5130 | } | |
5131 | ||
5132 | /* Fall through to general case. */ | |
5133 | default: | |
5134 | /* If invariant, return as USE (unless CONST_INT). | |
5135 | Otherwise, not giv. */ | |
5136 | if (GET_CODE (x) == USE) | |
5137 | x = XEXP (x, 0); | |
5138 | ||
5139 | if (invariant_p (x) == 1) | |
5140 | { | |
5141 | if (GET_CODE (x) == CONST_INT) | |
5142 | return x; | |
5143 | else | |
5144 | return gen_rtx (USE, mode, x); | |
5145 | } | |
5146 | else | |
5147 | return 0; | |
5148 | } | |
5149 | } | |
5150 | \f | |
5151 | /* Help detect a giv that is calculated by several consecutive insns; | |
5152 | for example, | |
5153 | giv = biv * M | |
5154 | giv = giv + A | |
5155 | The caller has already identified the first insn P as having a giv as dest; | |
5156 | we check that all other insns that set the same register follow | |
5157 | immediately after P, that they alter nothing else, | |
5158 | and that the result of the last is still a giv. | |
5159 | ||
5160 | The value is 0 if the reg set in P is not really a giv. | |
5161 | Otherwise, the value is the amount gained by eliminating | |
5162 | all the consecutive insns that compute the value. | |
5163 | ||
5164 | FIRST_BENEFIT is the amount gained by eliminating the first insn, P. | |
5165 | SRC_REG is the reg of the biv; DEST_REG is the reg of the giv. | |
5166 | ||
5167 | The coefficients of the ultimate giv value are stored in | |
5168 | *MULT_VAL and *ADD_VAL. */ | |
5169 | ||
5170 | static int | |
5171 | consec_sets_giv (first_benefit, p, src_reg, dest_reg, | |
5172 | add_val, mult_val) | |
5173 | int first_benefit; | |
5174 | rtx p; | |
5175 | rtx src_reg; | |
5176 | rtx dest_reg; | |
5177 | rtx *add_val; | |
5178 | rtx *mult_val; | |
5179 | { | |
5180 | int count; | |
5181 | enum rtx_code code; | |
5182 | int benefit; | |
5183 | rtx temp; | |
5184 | rtx set; | |
5185 | ||
5186 | /* Indicate that this is a giv so that we can update the value produced in | |
5187 | each insn of the multi-insn sequence. | |
5188 | ||
5189 | This induction structure will be used only by the call to | |
5190 | general_induction_var below, so we can allocate it on our stack. | |
5191 | If this is a giv, our caller will replace the induct var entry with | |
5192 | a new induction structure. */ | |
5193 | struct induction *v | |
5194 | = (struct induction *) alloca (sizeof (struct induction)); | |
5195 | v->src_reg = src_reg; | |
5196 | v->mult_val = *mult_val; | |
5197 | v->add_val = *add_val; | |
5198 | v->benefit = first_benefit; | |
5199 | v->cant_derive = 0; | |
5200 | v->derive_adjustment = 0; | |
5201 | ||
5202 | reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT; | |
5203 | reg_iv_info[REGNO (dest_reg)] = v; | |
5204 | ||
5205 | count = n_times_set[REGNO (dest_reg)] - 1; | |
5206 | ||
5207 | while (count > 0) | |
5208 | { | |
5209 | p = NEXT_INSN (p); | |
5210 | code = GET_CODE (p); | |
5211 | ||
5212 | /* If libcall, skip to end of call sequence. */ | |
5213 | if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
5214 | p = XEXP (temp, 0); | |
5215 | ||
5216 | if (code == INSN | |
5217 | && (set = single_set (p)) | |
5218 | && GET_CODE (SET_DEST (set)) == REG | |
5219 | && SET_DEST (set) == dest_reg | |
5220 | && ((benefit = general_induction_var (SET_SRC (set), &src_reg, | |
5221 | add_val, mult_val)) | |
5222 | /* Giv created by equivalent expression. */ | |
5223 | || ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX)) | |
5224 | && (benefit = general_induction_var (XEXP (temp, 0), &src_reg, | |
5225 | add_val, mult_val)))) | |
5226 | && src_reg == v->src_reg) | |
5227 | { | |
5228 | if (find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
5229 | benefit += libcall_benefit (p); | |
5230 | ||
5231 | count--; | |
5232 | v->mult_val = *mult_val; | |
5233 | v->add_val = *add_val; | |
5234 | v->benefit = benefit; | |
5235 | } | |
5236 | else if (code != NOTE) | |
5237 | { | |
5238 | /* Allow insns that set something other than this giv to a | |
5239 | constant. Such insns are needed on machines which cannot | |
5240 | include long constants and should not disqualify a giv. */ | |
5241 | if (code == INSN | |
5242 | && (set = single_set (p)) | |
5243 | && SET_DEST (set) != dest_reg | |
5244 | && CONSTANT_P (SET_SRC (set))) | |
5245 | continue; | |
5246 | ||
5247 | reg_iv_type[REGNO (dest_reg)] = UNKNOWN_INDUCT; | |
5248 | return 0; | |
5249 | } | |
5250 | } | |
5251 | ||
5252 | return v->benefit; | |
5253 | } | |
5254 | \f | |
5255 | /* Return an rtx, if any, that expresses giv G2 as a function of the register | |
5256 | represented by G1. If no such expression can be found, or it is clear that | |
5257 | it cannot possibly be a valid address, 0 is returned. | |
5258 | ||
5259 | To perform the computation, we note that | |
5260 | G1 = a * v + b and | |
5261 | G2 = c * v + d | |
5262 | where `v' is the biv. | |
5263 | ||
5264 | So G2 = (c/a) * G1 + (d - b*c/a) */ | |
5265 | ||
5266 | #ifdef ADDRESS_COST | |
5267 | static rtx | |
5268 | express_from (g1, g2) | |
5269 | struct induction *g1, *g2; | |
5270 | { | |
5271 | rtx mult, add; | |
5272 | ||
5273 | /* The value that G1 will be multiplied by must be a constant integer. Also, | |
5274 | the only chance we have of getting a valid address is if b*c/a (see above | |
5275 | for notation) is also an integer. */ | |
5276 | if (GET_CODE (g1->mult_val) != CONST_INT | |
5277 | || GET_CODE (g2->mult_val) != CONST_INT | |
5278 | || GET_CODE (g1->add_val) != CONST_INT | |
5279 | || g1->mult_val == const0_rtx | |
5280 | || INTVAL (g2->mult_val) % INTVAL (g1->mult_val) != 0) | |
5281 | return 0; | |
5282 | ||
5283 | mult = GEN_INT (INTVAL (g2->mult_val) / INTVAL (g1->mult_val)); | |
5284 | add = plus_constant (g2->add_val, - INTVAL (g1->add_val) * INTVAL (mult)); | |
5285 | ||
5286 | /* Form simplified final result. */ | |
5287 | if (mult == const0_rtx) | |
5288 | return add; | |
5289 | else if (mult == const1_rtx) | |
5290 | mult = g1->dest_reg; | |
5291 | else | |
5292 | mult = gen_rtx (MULT, g2->mode, g1->dest_reg, mult); | |
5293 | ||
5294 | if (add == const0_rtx) | |
5295 | return mult; | |
5296 | else | |
5297 | return gen_rtx (PLUS, g2->mode, mult, add); | |
5298 | } | |
5299 | #endif | |
5300 | \f | |
5301 | /* Return 1 if giv G2 can be combined with G1. This means that G2 can use | |
5302 | (either directly or via an address expression) a register used to represent | |
5303 | G1. Set g2->new_reg to a represtation of G1 (normally just | |
5304 | g1->dest_reg). */ | |
5305 | ||
5306 | static int | |
5307 | combine_givs_p (g1, g2) | |
5308 | struct induction *g1, *g2; | |
5309 | { | |
5310 | rtx tem; | |
5311 | ||
5312 | /* If these givs are identical, they can be combined. */ | |
5313 | if (rtx_equal_p (g1->mult_val, g2->mult_val) | |
5314 | && rtx_equal_p (g1->add_val, g2->add_val)) | |
5315 | { | |
5316 | g2->new_reg = g1->dest_reg; | |
5317 | return 1; | |
5318 | } | |
5319 | ||
5320 | #ifdef ADDRESS_COST | |
5321 | /* If G2 can be expressed as a function of G1 and that function is valid | |
5322 | as an address and no more expensive than using a register for G2, | |
5323 | the expression of G2 in terms of G1 can be used. */ | |
5324 | if (g2->giv_type == DEST_ADDR | |
5325 | && (tem = express_from (g1, g2)) != 0 | |
5326 | && memory_address_p (g2->mem_mode, tem) | |
5327 | && ADDRESS_COST (tem) <= ADDRESS_COST (*g2->location)) | |
5328 | { | |
5329 | g2->new_reg = tem; | |
5330 | return 1; | |
5331 | } | |
5332 | #endif | |
5333 | ||
5334 | return 0; | |
5335 | } | |
5336 | \f | |
5337 | /* Check all pairs of givs for iv_class BL and see if any can be combined with | |
5338 | any other. If so, point SAME to the giv combined with and set NEW_REG to | |
5339 | be an expression (in terms of the other giv's DEST_REG) equivalent to the | |
5340 | giv. Also, update BENEFIT and related fields for cost/benefit analysis. */ | |
5341 | ||
5342 | static void | |
5343 | combine_givs (bl) | |
5344 | struct iv_class *bl; | |
5345 | { | |
5346 | struct induction *g1, *g2; | |
5347 | int pass; | |
5348 | ||
5349 | for (g1 = bl->giv; g1; g1 = g1->next_iv) | |
5350 | for (pass = 0; pass <= 1; pass++) | |
5351 | for (g2 = bl->giv; g2; g2 = g2->next_iv) | |
5352 | if (g1 != g2 | |
5353 | /* First try to combine with replaceable givs, then all givs. */ | |
5354 | && (g1->replaceable || pass == 1) | |
5355 | /* If either has already been combined or is to be ignored, can't | |
5356 | combine. */ | |
5357 | && ! g1->ignore && ! g2->ignore && ! g1->same && ! g2->same | |
5358 | /* If something has been based on G2, G2 cannot itself be based | |
5359 | on something else. */ | |
5360 | && ! g2->combined_with | |
5361 | && combine_givs_p (g1, g2)) | |
5362 | { | |
5363 | /* g2->new_reg set by `combine_givs_p' */ | |
5364 | g2->same = g1; | |
5365 | g1->combined_with = 1; | |
5366 | g1->benefit += g2->benefit; | |
5367 | /* ??? The new final_[bg]iv_value code does a much better job | |
5368 | of finding replaceable giv's, and hence this code may no | |
5369 | longer be necessary. */ | |
5370 | if (! g2->replaceable && REG_USERVAR_P (g2->dest_reg)) | |
5371 | g1->benefit -= copy_cost; | |
5372 | g1->lifetime += g2->lifetime; | |
5373 | g1->times_used += g2->times_used; | |
5374 | ||
5375 | if (loop_dump_stream) | |
5376 | fprintf (loop_dump_stream, "giv at %d combined with giv at %d\n", | |
5377 | INSN_UID (g2->insn), INSN_UID (g1->insn)); | |
5378 | } | |
5379 | } | |
5380 | \f | |
5381 | /* EMIT code before INSERT_BEFORE to set REG = B * M + A. */ | |
5382 | ||
5383 | void | |
5384 | emit_iv_add_mult (b, m, a, reg, insert_before) | |
5385 | rtx b; /* initial value of basic induction variable */ | |
5386 | rtx m; /* multiplicative constant */ | |
5387 | rtx a; /* additive constant */ | |
5388 | rtx reg; /* destination register */ | |
5389 | rtx insert_before; | |
5390 | { | |
5391 | rtx seq; | |
5392 | rtx result; | |
5393 | ||
5394 | /* Prevent unexpected sharing of these rtx. */ | |
5395 | a = copy_rtx (a); | |
5396 | b = copy_rtx (b); | |
5397 | ||
5398 | /* Increase the lifetime of any invariants moved further in code. */ | |
5399 | update_reg_last_use (a, insert_before); | |
5400 | update_reg_last_use (b, insert_before); | |
5401 | update_reg_last_use (m, insert_before); | |
5402 | ||
5403 | start_sequence (); | |
5404 | result = expand_mult_add (b, reg, m, a, GET_MODE (reg), 0); | |
5405 | if (reg != result) | |
5406 | emit_move_insn (reg, result); | |
5407 | seq = gen_sequence (); | |
5408 | end_sequence (); | |
5409 | ||
5410 | emit_insn_before (seq, insert_before); | |
5411 | } | |
5412 | \f | |
5413 | /* Test whether A * B can be computed without | |
5414 | an actual multiply insn. Value is 1 if so. */ | |
5415 | ||
5416 | static int | |
5417 | product_cheap_p (a, b) | |
5418 | rtx a; | |
5419 | rtx b; | |
5420 | { | |
5421 | int i; | |
5422 | rtx tmp; | |
5423 | struct obstack *old_rtl_obstack = rtl_obstack; | |
5424 | char *storage = (char *) obstack_alloc (&temp_obstack, 0); | |
5425 | int win = 1; | |
5426 | ||
5427 | /* If only one is constant, make it B. */ | |
5428 | if (GET_CODE (a) == CONST_INT) | |
5429 | tmp = a, a = b, b = tmp; | |
5430 | ||
5431 | /* If first constant, both constant, so don't need multiply. */ | |
5432 | if (GET_CODE (a) == CONST_INT) | |
5433 | return 1; | |
5434 | ||
5435 | /* If second not constant, neither is constant, so would need multiply. */ | |
5436 | if (GET_CODE (b) != CONST_INT) | |
5437 | return 0; | |
5438 | ||
5439 | /* One operand is constant, so might not need multiply insn. Generate the | |
5440 | code for the multiply and see if a call or multiply, or long sequence | |
5441 | of insns is generated. */ | |
5442 | ||
5443 | rtl_obstack = &temp_obstack; | |
5444 | start_sequence (); | |
5445 | expand_mult (GET_MODE (a), a, b, NULL_RTX, 0); | |
5446 | tmp = gen_sequence (); | |
5447 | end_sequence (); | |
5448 | ||
5449 | if (GET_CODE (tmp) == SEQUENCE) | |
5450 | { | |
5451 | if (XVEC (tmp, 0) == 0) | |
5452 | win = 1; | |
5453 | else if (XVECLEN (tmp, 0) > 3) | |
5454 | win = 0; | |
5455 | else | |
5456 | for (i = 0; i < XVECLEN (tmp, 0); i++) | |
5457 | { | |
5458 | rtx insn = XVECEXP (tmp, 0, i); | |
5459 | ||
5460 | if (GET_CODE (insn) != INSN | |
5461 | || (GET_CODE (PATTERN (insn)) == SET | |
5462 | && GET_CODE (SET_SRC (PATTERN (insn))) == MULT) | |
5463 | || (GET_CODE (PATTERN (insn)) == PARALLEL | |
5464 | && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET | |
5465 | && GET_CODE (SET_SRC (XVECEXP (PATTERN (insn), 0, 0))) == MULT)) | |
5466 | { | |
5467 | win = 0; | |
5468 | break; | |
5469 | } | |
5470 | } | |
5471 | } | |
5472 | else if (GET_CODE (tmp) == SET | |
5473 | && GET_CODE (SET_SRC (tmp)) == MULT) | |
5474 | win = 0; | |
5475 | else if (GET_CODE (tmp) == PARALLEL | |
5476 | && GET_CODE (XVECEXP (tmp, 0, 0)) == SET | |
5477 | && GET_CODE (SET_SRC (XVECEXP (tmp, 0, 0))) == MULT) | |
5478 | win = 0; | |
5479 | ||
5480 | /* Free any storage we obtained in generating this multiply and restore rtl | |
5481 | allocation to its normal obstack. */ | |
5482 | obstack_free (&temp_obstack, storage); | |
5483 | rtl_obstack = old_rtl_obstack; | |
5484 | ||
5485 | return win; | |
5486 | } | |
5487 | \f | |
5488 | /* Check to see if loop can be terminated by a "decrement and branch until | |
5489 | zero" instruction. If so, add a REG_NONNEG note to the branch insn if so. | |
5490 | Also try reversing an increment loop to a decrement loop | |
5491 | to see if the optimization can be performed. | |
5492 | Value is nonzero if optimization was performed. */ | |
5493 | ||
5494 | /* This is useful even if the architecture doesn't have such an insn, | |
5495 | because it might change a loops which increments from 0 to n to a loop | |
5496 | which decrements from n to 0. A loop that decrements to zero is usually | |
5497 | faster than one that increments from zero. */ | |
5498 | ||
5499 | /* ??? This could be rewritten to use some of the loop unrolling procedures, | |
5500 | such as approx_final_value, biv_total_increment, loop_iterations, and | |
5501 | final_[bg]iv_value. */ | |
5502 | ||
5503 | static int | |
5504 | check_dbra_loop (loop_end, insn_count, loop_start) | |
5505 | rtx loop_end; | |
5506 | int insn_count; | |
5507 | rtx loop_start; | |
5508 | { | |
5509 | struct iv_class *bl; | |
5510 | rtx reg; | |
5511 | rtx jump_label; | |
5512 | rtx final_value; | |
5513 | rtx start_value; | |
5514 | enum rtx_code branch_code; | |
5515 | rtx new_add_val; | |
5516 | rtx comparison; | |
5517 | rtx before_comparison; | |
5518 | rtx p; | |
5519 | ||
5520 | /* If last insn is a conditional branch, and the insn before tests a | |
5521 | register value, try to optimize it. Otherwise, we can't do anything. */ | |
5522 | ||
5523 | comparison = get_condition_for_loop (PREV_INSN (loop_end)); | |
5524 | if (comparison == 0) | |
5525 | return 0; | |
5526 | ||
5527 | /* Check all of the bivs to see if the compare uses one of them. | |
5528 | Skip biv's set more than once because we can't guarantee that | |
5529 | it will be zero on the last iteration. Also skip if the biv is | |
5530 | used between its update and the test insn. */ | |
5531 | ||
5532 | for (bl = loop_iv_list; bl; bl = bl->next) | |
5533 | { | |
5534 | if (bl->biv_count == 1 | |
5535 | && bl->biv->dest_reg == XEXP (comparison, 0) | |
5536 | && ! reg_used_between_p (regno_reg_rtx[bl->regno], bl->biv->insn, | |
5537 | PREV_INSN (PREV_INSN (loop_end)))) | |
5538 | break; | |
5539 | } | |
5540 | ||
5541 | if (! bl) | |
5542 | return 0; | |
5543 | ||
5544 | /* Look for the case where the basic induction variable is always | |
5545 | nonnegative, and equals zero on the last iteration. | |
5546 | In this case, add a reg_note REG_NONNEG, which allows the | |
5547 | m68k DBRA instruction to be used. */ | |
5548 | ||
5549 | if (((GET_CODE (comparison) == GT | |
5550 | && GET_CODE (XEXP (comparison, 1)) == CONST_INT | |
5551 | && INTVAL (XEXP (comparison, 1)) == -1) | |
5552 | || (GET_CODE (comparison) == NE && XEXP (comparison, 1) == const0_rtx)) | |
5553 | && GET_CODE (bl->biv->add_val) == CONST_INT | |
5554 | && INTVAL (bl->biv->add_val) < 0) | |
5555 | { | |
5556 | /* Initial value must be greater than 0, | |
5557 | init_val % -dec_value == 0 to ensure that it equals zero on | |
5558 | the last iteration */ | |
5559 | ||
5560 | if (GET_CODE (bl->initial_value) == CONST_INT | |
5561 | && INTVAL (bl->initial_value) > 0 | |
5562 | && (INTVAL (bl->initial_value) % | |
5563 | (-INTVAL (bl->biv->add_val))) == 0) | |
5564 | { | |
5565 | /* register always nonnegative, add REG_NOTE to branch */ | |
5566 | REG_NOTES (PREV_INSN (loop_end)) | |
5567 | = gen_rtx (EXPR_LIST, REG_NONNEG, NULL_RTX, | |
5568 | REG_NOTES (PREV_INSN (loop_end))); | |
5569 | bl->nonneg = 1; | |
5570 | ||
5571 | return 1; | |
5572 | } | |
5573 | ||
5574 | /* If the decrement is 1 and the value was tested as >= 0 before | |
5575 | the loop, then we can safely optimize. */ | |
5576 | for (p = loop_start; p; p = PREV_INSN (p)) | |
5577 | { | |
5578 | if (GET_CODE (p) == CODE_LABEL) | |
5579 | break; | |
5580 | if (GET_CODE (p) != JUMP_INSN) | |
5581 | continue; | |
5582 | ||
5583 | before_comparison = get_condition_for_loop (p); | |
5584 | if (before_comparison | |
5585 | && XEXP (before_comparison, 0) == bl->biv->dest_reg | |
5586 | && GET_CODE (before_comparison) == LT | |
5587 | && XEXP (before_comparison, 1) == const0_rtx | |
5588 | && ! reg_set_between_p (bl->biv->dest_reg, p, loop_start) | |
5589 | && INTVAL (bl->biv->add_val) == -1) | |
5590 | { | |
5591 | REG_NOTES (PREV_INSN (loop_end)) | |
5592 | = gen_rtx (EXPR_LIST, REG_NONNEG, NULL_RTX, | |
5593 | REG_NOTES (PREV_INSN (loop_end))); | |
5594 | bl->nonneg = 1; | |
5595 | ||
5596 | return 1; | |
5597 | } | |
5598 | } | |
5599 | } | |
5600 | else if (num_mem_sets <= 1) | |
5601 | { | |
5602 | /* Try to change inc to dec, so can apply above optimization. */ | |
5603 | /* Can do this if: | |
5604 | all registers modified are induction variables or invariant, | |
5605 | all memory references have non-overlapping addresses | |
5606 | (obviously true if only one write) | |
5607 | allow 2 insns for the compare/jump at the end of the loop. */ | |
5608 | int num_nonfixed_reads = 0; | |
5609 | /* 1 if the iteration var is used only to count iterations. */ | |
5610 | int no_use_except_counting = 0; | |
5611 | ||
5612 | for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) | |
5613 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i') | |
5614 | num_nonfixed_reads += count_nonfixed_reads (PATTERN (p)); | |
5615 | ||
5616 | if (bl->giv_count == 0 | |
5617 | && ! loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
5618 | { | |
5619 | rtx bivreg = regno_reg_rtx[bl->regno]; | |
5620 | ||
5621 | /* If there are no givs for this biv, and the only exit is the | |
5622 | fall through at the end of the the loop, then | |
5623 | see if perhaps there are no uses except to count. */ | |
5624 | no_use_except_counting = 1; | |
5625 | for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) | |
5626 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i') | |
5627 | { | |
5628 | rtx set = single_set (p); | |
5629 | ||
5630 | if (set && GET_CODE (SET_DEST (set)) == REG | |
5631 | && REGNO (SET_DEST (set)) == bl->regno) | |
5632 | /* An insn that sets the biv is okay. */ | |
5633 | ; | |
5634 | else if (p == prev_nonnote_insn (prev_nonnote_insn (loop_end)) | |
5635 | || p == prev_nonnote_insn (loop_end)) | |
5636 | /* Don't bother about the end test. */ | |
5637 | ; | |
5638 | else if (reg_mentioned_p (bivreg, PATTERN (p))) | |
5639 | /* Any other use of the biv is no good. */ | |
5640 | { | |
5641 | no_use_except_counting = 0; | |
5642 | break; | |
5643 | } | |
5644 | } | |
5645 | } | |
5646 | ||
5647 | /* This code only acts for innermost loops. Also it simplifies | |
5648 | the memory address check by only reversing loops with | |
5649 | zero or one memory access. | |
5650 | Two memory accesses could involve parts of the same array, | |
5651 | and that can't be reversed. */ | |
5652 | ||
5653 | if (num_nonfixed_reads <= 1 | |
5654 | && !loop_has_call | |
5655 | && !loop_has_volatile | |
5656 | && (no_use_except_counting | |
5657 | || (bl->giv_count + bl->biv_count + num_mem_sets | |
5658 | + num_movables + 2 == insn_count))) | |
5659 | { | |
5660 | rtx condition = get_condition_for_loop (PREV_INSN (loop_end)); | |
5661 | int win; | |
5662 | rtx tem; | |
5663 | ||
5664 | /* Loop can be reversed. */ | |
5665 | if (loop_dump_stream) | |
5666 | fprintf (loop_dump_stream, "Can reverse loop\n"); | |
5667 | ||
5668 | /* Now check other conditions: | |
5669 | initial_value must be zero, | |
5670 | final_value % add_val == 0, so that when reversed, the | |
5671 | biv will be zero on the last iteration. | |
5672 | ||
5673 | This test can probably be improved since +/- 1 in the constant | |
5674 | can be obtained by changing LT to LE and vice versa; this is | |
5675 | confusing. */ | |
5676 | ||
5677 | if (comparison && bl->initial_value == const0_rtx | |
5678 | && GET_CODE (XEXP (comparison, 1)) == CONST_INT | |
5679 | /* LE gets turned into LT */ | |
5680 | && GET_CODE (comparison) == LT | |
5681 | && (INTVAL (XEXP (comparison, 1)) | |
5682 | % INTVAL (bl->biv->add_val)) == 0) | |
5683 | { | |
5684 | /* Register will always be nonnegative, with value | |
5685 | 0 on last iteration if loop reversed */ | |
5686 | ||
5687 | /* Save some info needed to produce the new insns. */ | |
5688 | reg = bl->biv->dest_reg; | |
5689 | jump_label = XEXP (SET_SRC (PATTERN (PREV_INSN (loop_end))), 1); | |
5690 | new_add_val = GEN_INT (- INTVAL (bl->biv->add_val)); | |
5691 | ||
5692 | final_value = XEXP (comparison, 1); | |
5693 | start_value = GEN_INT (INTVAL (XEXP (comparison, 1)) | |
5694 | - INTVAL (bl->biv->add_val)); | |
5695 | ||
5696 | /* Initialize biv to start_value before loop start. | |
5697 | The old initializing insn will be deleted as a | |
5698 | dead store by flow.c. */ | |
5699 | emit_insn_before (gen_move_insn (reg, start_value), loop_start); | |
5700 | ||
5701 | /* Add insn to decrement register, and delete insn | |
5702 | that incremented the register. */ | |
5703 | p = emit_insn_before (gen_add2_insn (reg, new_add_val), | |
5704 | bl->biv->insn); | |
5705 | delete_insn (bl->biv->insn); | |
5706 | ||
5707 | /* Update biv info to reflect its new status. */ | |
5708 | bl->biv->insn = p; | |
5709 | bl->initial_value = start_value; | |
5710 | bl->biv->add_val = new_add_val; | |
5711 | ||
5712 | /* Inc LABEL_NUSES so that delete_insn will | |
5713 | not delete the label. */ | |
5714 | LABEL_NUSES (XEXP (jump_label, 0)) ++; | |
5715 | ||
5716 | /* Emit an insn after the end of the loop to set the biv's | |
5717 | proper exit value if it is used anywhere outside the loop. */ | |
5718 | if ((regno_last_uid[bl->regno] | |
5719 | != INSN_UID (PREV_INSN (PREV_INSN (loop_end)))) | |
5720 | || ! bl->init_insn | |
5721 | || regno_first_uid[bl->regno] != INSN_UID (bl->init_insn)) | |
5722 | emit_insn_after (gen_move_insn (reg, final_value), | |
5723 | loop_end); | |
5724 | ||
5725 | /* Delete compare/branch at end of loop. */ | |
5726 | delete_insn (PREV_INSN (loop_end)); | |
5727 | delete_insn (PREV_INSN (loop_end)); | |
5728 | ||
5729 | /* Add new compare/branch insn at end of loop. */ | |
5730 | start_sequence (); | |
5731 | emit_cmp_insn (reg, const0_rtx, GE, NULL_RTX, | |
5732 | GET_MODE (reg), 0, 0); | |
5733 | emit_jump_insn (gen_bge (XEXP (jump_label, 0))); | |
5734 | tem = gen_sequence (); | |
5735 | end_sequence (); | |
5736 | emit_jump_insn_before (tem, loop_end); | |
5737 | ||
5738 | for (tem = PREV_INSN (loop_end); | |
5739 | tem && GET_CODE (tem) != JUMP_INSN; tem = PREV_INSN (tem)) | |
5740 | ; | |
5741 | if (tem) | |
5742 | { | |
5743 | JUMP_LABEL (tem) = XEXP (jump_label, 0); | |
5744 | ||
5745 | /* Increment of LABEL_NUSES done above. */ | |
5746 | /* Register is now always nonnegative, | |
5747 | so add REG_NONNEG note to the branch. */ | |
5748 | REG_NOTES (tem) = gen_rtx (EXPR_LIST, REG_NONNEG, NULL_RTX, | |
5749 | REG_NOTES (tem)); | |
5750 | } | |
5751 | ||
5752 | bl->nonneg = 1; | |
5753 | ||
5754 | /* Mark that this biv has been reversed. Each giv which depends | |
5755 | on this biv, and which is also live past the end of the loop | |
5756 | will have to be fixed up. */ | |
5757 | ||
5758 | bl->reversed = 1; | |
5759 | ||
5760 | if (loop_dump_stream) | |
5761 | fprintf (loop_dump_stream, | |
5762 | "Reversed loop and added reg_nonneg\n"); | |
5763 | ||
5764 | return 1; | |
5765 | } | |
5766 | } | |
5767 | } | |
5768 | ||
5769 | return 0; | |
5770 | } | |
5771 | \f | |
5772 | /* Verify whether the biv BL appears to be eliminable, | |
5773 | based on the insns in the loop that refer to it. | |
5774 | LOOP_START is the first insn of the loop, and END is the end insn. | |
5775 | ||
5776 | If ELIMINATE_P is non-zero, actually do the elimination. | |
5777 | ||
5778 | THRESHOLD and INSN_COUNT are from loop_optimize and are used to | |
5779 | determine whether invariant insns should be placed inside or at the | |
5780 | start of the loop. */ | |
5781 | ||
5782 | static int | |
5783 | maybe_eliminate_biv (bl, loop_start, end, eliminate_p, threshold, insn_count) | |
5784 | struct iv_class *bl; | |
5785 | rtx loop_start; | |
5786 | rtx end; | |
5787 | int eliminate_p; | |
5788 | int threshold, insn_count; | |
5789 | { | |
5790 | rtx reg = bl->biv->dest_reg; | |
5791 | rtx p, set; | |
5792 | struct induction *v; | |
5793 | ||
5794 | /* Scan all insns in the loop, stopping if we find one that uses the | |
5795 | biv in a way that we cannot eliminate. */ | |
5796 | ||
5797 | for (p = loop_start; p != end; p = NEXT_INSN (p)) | |
5798 | { | |
5799 | enum rtx_code code = GET_CODE (p); | |
5800 | rtx where = threshold >= insn_count ? loop_start : p; | |
5801 | ||
5802 | if ((code == INSN || code == JUMP_INSN || code == CALL_INSN) | |
5803 | && reg_mentioned_p (reg, PATTERN (p)) | |
5804 | && ! maybe_eliminate_biv_1 (PATTERN (p), p, bl, eliminate_p, where)) | |
5805 | { | |
5806 | if (loop_dump_stream) | |
5807 | fprintf (loop_dump_stream, | |
5808 | "Cannot eliminate biv %d: biv used in insn %d.\n", | |
5809 | bl->regno, INSN_UID (p)); | |
5810 | break; | |
5811 | } | |
5812 | } | |
5813 | ||
5814 | if (p == end) | |
5815 | { | |
5816 | if (loop_dump_stream) | |
5817 | fprintf (loop_dump_stream, "biv %d %s eliminated.\n", | |
5818 | bl->regno, eliminate_p ? "was" : "can be"); | |
5819 | return 1; | |
5820 | } | |
5821 | ||
5822 | return 0; | |
5823 | } | |
5824 | \f | |
5825 | /* If BL appears in X (part of the pattern of INSN), see if we can | |
5826 | eliminate its use. If so, return 1. If not, return 0. | |
5827 | ||
5828 | If BIV does not appear in X, return 1. | |
5829 | ||
5830 | If ELIMINATE_P is non-zero, actually do the elimination. WHERE indicates | |
5831 | where extra insns should be added. Depending on how many items have been | |
5832 | moved out of the loop, it will either be before INSN or at the start of | |
5833 | the loop. */ | |
5834 | ||
5835 | static int | |
5836 | maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where) | |
5837 | rtx x, insn; | |
5838 | struct iv_class *bl; | |
5839 | int eliminate_p; | |
5840 | rtx where; | |
5841 | { | |
5842 | enum rtx_code code = GET_CODE (x); | |
5843 | rtx reg = bl->biv->dest_reg; | |
5844 | enum machine_mode mode = GET_MODE (reg); | |
5845 | struct induction *v; | |
5846 | rtx arg, new, tem; | |
5847 | int arg_operand; | |
5848 | char *fmt; | |
5849 | int i, j; | |
5850 | ||
5851 | switch (code) | |
5852 | { | |
5853 | case REG: | |
5854 | /* If we haven't already been able to do something with this BIV, | |
5855 | we can't eliminate it. */ | |
5856 | if (x == reg) | |
5857 | return 0; | |
5858 | return 1; | |
5859 | ||
5860 | case SET: | |
5861 | /* If this sets the BIV, it is not a problem. */ | |
5862 | if (SET_DEST (x) == reg) | |
5863 | return 1; | |
5864 | ||
5865 | /* If this is an insn that defines a giv, it is also ok because | |
5866 | it will go away when the giv is reduced. */ | |
5867 | for (v = bl->giv; v; v = v->next_iv) | |
5868 | if (v->giv_type == DEST_REG && SET_DEST (x) == v->dest_reg) | |
5869 | return 1; | |
5870 | ||
5871 | #ifdef HAVE_cc0 | |
5872 | if (SET_DEST (x) == cc0_rtx && SET_SRC (x) == reg) | |
5873 | { | |
5874 | /* Can replace with any giv that was reduced and | |
5875 | that has (MULT_VAL != 0) and (ADD_VAL == 0). | |
5876 | Require a constant for MULT_VAL, so we know it's nonzero. */ | |
5877 | ||
5878 | for (v = bl->giv; v; v = v->next_iv) | |
5879 | if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx | |
5880 | && v->add_val == const0_rtx | |
5881 | && ! v->ignore && ! v->maybe_dead | |
5882 | && v->mode == mode) | |
5883 | { | |
5884 | if (! eliminate_p) | |
5885 | return 1; | |
5886 | ||
5887 | /* If the giv has the opposite direction of change, | |
5888 | then reverse the comparison. */ | |
5889 | if (INTVAL (v->mult_val) < 0) | |
5890 | new = gen_rtx (COMPARE, GET_MODE (v->new_reg), | |
5891 | const0_rtx, v->new_reg); | |
5892 | else | |
5893 | new = v->new_reg; | |
5894 | ||
5895 | /* We can probably test that giv's reduced reg. */ | |
5896 | if (validate_change (insn, &SET_SRC (x), new, 0)) | |
5897 | return 1; | |
5898 | } | |
5899 | ||
5900 | /* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0); | |
5901 | replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL). | |
5902 | Require a constant for MULT_VAL, so we know it's nonzero. */ | |
5903 | ||
5904 | for (v = bl->giv; v; v = v->next_iv) | |
5905 | if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx | |
5906 | && ! v->ignore && ! v->maybe_dead | |
5907 | && v->mode == mode) | |
5908 | { | |
5909 | if (! eliminate_p) | |
5910 | return 1; | |
5911 | ||
5912 | /* If the giv has the opposite direction of change, | |
5913 | then reverse the comparison. */ | |
5914 | if (INTVAL (v->mult_val) < 0) | |
5915 | new = gen_rtx (COMPARE, VOIDmode, copy_rtx (v->add_val), | |
5916 | v->new_reg); | |
5917 | else | |
5918 | new = gen_rtx (COMPARE, VOIDmode, v->new_reg, | |
5919 | copy_rtx (v->add_val)); | |
5920 | ||
5921 | /* Replace biv with the giv's reduced register. */ | |
5922 | update_reg_last_use (v->add_val, insn); | |
5923 | if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0)) | |
5924 | return 1; | |
5925 | ||
5926 | /* Insn doesn't support that constant or invariant. Copy it | |
5927 | into a register (it will be a loop invariant.) */ | |
5928 | tem = gen_reg_rtx (GET_MODE (v->new_reg)); | |
5929 | ||
5930 | emit_insn_before (gen_move_insn (tem, copy_rtx (v->add_val)), | |
5931 | where); | |
5932 | ||
5933 | if (validate_change (insn, &SET_SRC (PATTERN (insn)), | |
5934 | gen_rtx (COMPARE, VOIDmode, | |
5935 | v->new_reg, tem), 0)) | |
5936 | return 1; | |
5937 | } | |
5938 | } | |
5939 | #endif | |
5940 | break; | |
5941 | ||
5942 | case COMPARE: | |
5943 | case EQ: case NE: | |
5944 | case GT: case GE: case GTU: case GEU: | |
5945 | case LT: case LE: case LTU: case LEU: | |
5946 | /* See if either argument is the biv. */ | |
5947 | if (XEXP (x, 0) == reg) | |
5948 | arg = XEXP (x, 1), arg_operand = 1; | |
5949 | else if (XEXP (x, 1) == reg) | |
5950 | arg = XEXP (x, 0), arg_operand = 0; | |
5951 | else | |
5952 | break; | |
5953 | ||
5954 | if (CONSTANT_P (arg)) | |
5955 | { | |
5956 | /* First try to replace with any giv that has constant positive | |
5957 | mult_val and constant add_val. We might be able to support | |
5958 | negative mult_val, but it seems complex to do it in general. */ | |
5959 | ||
5960 | for (v = bl->giv; v; v = v->next_iv) | |
5961 | if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0 | |
5962 | && CONSTANT_P (v->add_val) | |
5963 | && ! v->ignore && ! v->maybe_dead | |
5964 | && v->mode == mode) | |
5965 | { | |
5966 | if (! eliminate_p) | |
5967 | return 1; | |
5968 | ||
5969 | /* Replace biv with the giv's reduced reg. */ | |
5970 | XEXP (x, 1-arg_operand) = v->new_reg; | |
5971 | ||
5972 | /* If all constants are actually constant integers and | |
5973 | the derived constant can be directly placed in the COMPARE, | |
5974 | do so. */ | |
5975 | if (GET_CODE (arg) == CONST_INT | |
5976 | && GET_CODE (v->mult_val) == CONST_INT | |
5977 | && GET_CODE (v->add_val) == CONST_INT | |
5978 | && validate_change (insn, &XEXP (x, arg_operand), | |
5979 | GEN_INT (INTVAL (arg) | |
5980 | * INTVAL (v->mult_val) | |
5981 | + INTVAL (v->add_val)), 0)) | |
5982 | return 1; | |
5983 | ||
5984 | /* Otherwise, load it into a register. */ | |
5985 | tem = gen_reg_rtx (mode); | |
5986 | emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where); | |
5987 | if (validate_change (insn, &XEXP (x, arg_operand), tem, 0)) | |
5988 | return 1; | |
5989 | ||
5990 | /* If that failed, put back the change we made above. */ | |
5991 | XEXP (x, 1-arg_operand) = reg; | |
5992 | } | |
5993 | ||
5994 | /* Look for giv with positive constant mult_val and nonconst add_val. | |
5995 | Insert insns to calculate new compare value. */ | |
5996 | ||
5997 | for (v = bl->giv; v; v = v->next_iv) | |
5998 | if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0 | |
5999 | && ! v->ignore && ! v->maybe_dead | |
6000 | && v->mode == mode) | |
6001 | { | |
6002 | rtx tem; | |
6003 | ||
6004 | if (! eliminate_p) | |
6005 | return 1; | |
6006 | ||
6007 | tem = gen_reg_rtx (mode); | |
6008 | ||
6009 | /* Replace biv with giv's reduced register. */ | |
6010 | validate_change (insn, &XEXP (x, 1 - arg_operand), | |
6011 | v->new_reg, 1); | |
6012 | ||
6013 | /* Compute value to compare against. */ | |
6014 | emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where); | |
6015 | /* Use it in this insn. */ | |
6016 | validate_change (insn, &XEXP (x, arg_operand), tem, 1); | |
6017 | if (apply_change_group ()) | |
6018 | return 1; | |
6019 | } | |
6020 | } | |
6021 | else if (GET_CODE (arg) == REG || GET_CODE (arg) == MEM) | |
6022 | { | |
6023 | if (invariant_p (arg) == 1) | |
6024 | { | |
6025 | /* Look for giv with constant positive mult_val and nonconst | |
6026 | add_val. Insert insns to compute new compare value. */ | |
6027 | ||
6028 | for (v = bl->giv; v; v = v->next_iv) | |
6029 | if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0 | |
6030 | && ! v->ignore && ! v->maybe_dead | |
6031 | && v->mode == mode) | |
6032 | { | |
6033 | rtx tem; | |
6034 | ||
6035 | if (! eliminate_p) | |
6036 | return 1; | |
6037 | ||
6038 | tem = gen_reg_rtx (mode); | |
6039 | ||
6040 | /* Replace biv with giv's reduced register. */ | |
6041 | validate_change (insn, &XEXP (x, 1 - arg_operand), | |
6042 | v->new_reg, 1); | |
6043 | ||
6044 | /* Compute value to compare against. */ | |
6045 | emit_iv_add_mult (arg, v->mult_val, v->add_val, | |
6046 | tem, where); | |
6047 | validate_change (insn, &XEXP (x, arg_operand), tem, 1); | |
6048 | if (apply_change_group ()) | |
6049 | return 1; | |
6050 | } | |
6051 | } | |
6052 | ||
6053 | /* This code has problems. Basically, you can't know when | |
6054 | seeing if we will eliminate BL, whether a particular giv | |
6055 | of ARG will be reduced. If it isn't going to be reduced, | |
6056 | we can't eliminate BL. We can try forcing it to be reduced, | |
6057 | but that can generate poor code. | |
6058 | ||
6059 | The problem is that the benefit of reducing TV, below should | |
6060 | be increased if BL can actually be eliminated, but this means | |
6061 | we might have to do a topological sort of the order in which | |
6062 | we try to process biv. It doesn't seem worthwhile to do | |
6063 | this sort of thing now. */ | |
6064 | ||
6065 | #if 0 | |
6066 | /* Otherwise the reg compared with had better be a biv. */ | |
6067 | if (GET_CODE (arg) != REG | |
6068 | || reg_iv_type[REGNO (arg)] != BASIC_INDUCT) | |
6069 | return 0; | |
6070 | ||
6071 | /* Look for a pair of givs, one for each biv, | |
6072 | with identical coefficients. */ | |
6073 | for (v = bl->giv; v; v = v->next_iv) | |
6074 | { | |
6075 | struct induction *tv; | |
6076 | ||
6077 | if (v->ignore || v->maybe_dead || v->mode != mode) | |
6078 | continue; | |
6079 | ||
6080 | for (tv = reg_biv_class[REGNO (arg)]->giv; tv; tv = tv->next_iv) | |
6081 | if (! tv->ignore && ! tv->maybe_dead | |
6082 | && rtx_equal_p (tv->mult_val, v->mult_val) | |
6083 | && rtx_equal_p (tv->add_val, v->add_val) | |
6084 | && tv->mode == mode) | |
6085 | { | |
6086 | if (! eliminate_p) | |
6087 | return 1; | |
6088 | ||
6089 | /* Replace biv with its giv's reduced reg. */ | |
6090 | XEXP (x, 1-arg_operand) = v->new_reg; | |
6091 | /* Replace other operand with the other giv's | |
6092 | reduced reg. */ | |
6093 | XEXP (x, arg_operand) = tv->new_reg; | |
6094 | return 1; | |
6095 | } | |
6096 | } | |
6097 | #endif | |
6098 | } | |
6099 | ||
6100 | /* If we get here, the biv can't be eliminated. */ | |
6101 | return 0; | |
6102 | ||
6103 | case MEM: | |
6104 | /* If this address is a DEST_ADDR giv, it doesn't matter if the | |
6105 | biv is used in it, since it will be replaced. */ | |
6106 | for (v = bl->giv; v; v = v->next_iv) | |
6107 | if (v->giv_type == DEST_ADDR && v->location == &XEXP (x, 0)) | |
6108 | return 1; | |
6109 | break; | |
6110 | } | |
6111 | ||
6112 | /* See if any subexpression fails elimination. */ | |
6113 | fmt = GET_RTX_FORMAT (code); | |
6114 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
6115 | { | |
6116 | switch (fmt[i]) | |
6117 | { | |
6118 | case 'e': | |
6119 | if (! maybe_eliminate_biv_1 (XEXP (x, i), insn, bl, | |
6120 | eliminate_p, where)) | |
6121 | return 0; | |
6122 | break; | |
6123 | ||
6124 | case 'E': | |
6125 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
6126 | if (! maybe_eliminate_biv_1 (XVECEXP (x, i, j), insn, bl, | |
6127 | eliminate_p, where)) | |
6128 | return 0; | |
6129 | break; | |
6130 | } | |
6131 | } | |
6132 | ||
6133 | return 1; | |
6134 | } | |
6135 | \f | |
6136 | /* Return nonzero if the last use of REG | |
6137 | is in an insn following INSN in the same basic block. */ | |
6138 | ||
6139 | static int | |
6140 | last_use_this_basic_block (reg, insn) | |
6141 | rtx reg; | |
6142 | rtx insn; | |
6143 | { | |
6144 | rtx n; | |
6145 | for (n = insn; | |
6146 | n && GET_CODE (n) != CODE_LABEL && GET_CODE (n) != JUMP_INSN; | |
6147 | n = NEXT_INSN (n)) | |
6148 | { | |
6149 | if (regno_last_uid[REGNO (reg)] == INSN_UID (n)) | |
6150 | return 1; | |
6151 | } | |
6152 | return 0; | |
6153 | } | |
6154 | \f | |
6155 | /* Called via `note_stores' to record the initial value of a biv. Here we | |
6156 | just record the location of the set and process it later. */ | |
6157 | ||
6158 | static void | |
6159 | record_initial (dest, set) | |
6160 | rtx dest; | |
6161 | rtx set; | |
6162 | { | |
6163 | struct iv_class *bl; | |
6164 | ||
6165 | if (GET_CODE (dest) != REG | |
6166 | || REGNO (dest) >= max_reg_before_loop | |
6167 | || reg_iv_type[REGNO (dest)] != BASIC_INDUCT) | |
6168 | return; | |
6169 | ||
6170 | bl = reg_biv_class[REGNO (dest)]; | |
6171 | ||
6172 | /* If this is the first set found, record it. */ | |
6173 | if (bl->init_insn == 0) | |
6174 | { | |
6175 | bl->init_insn = note_insn; | |
6176 | bl->init_set = set; | |
6177 | } | |
6178 | } | |
6179 | \f | |
6180 | /* If any of the registers in X are "old" and currently have a last use earlier | |
6181 | than INSN, update them to have a last use of INSN. Their actual last use | |
6182 | will be the previous insn but it will not have a valid uid_luid so we can't | |
6183 | use it. */ | |
6184 | ||
6185 | static void | |
6186 | update_reg_last_use (x, insn) | |
6187 | rtx x; | |
6188 | rtx insn; | |
6189 | { | |
6190 | /* Check for the case where INSN does not have a valid luid. In this case, | |
6191 | there is no need to modify the regno_last_uid, as this can only happen | |
6192 | when code is inserted after the loop_end to set a pseudo's final value, | |
6193 | and hence this insn will never be the last use of x. */ | |
6194 | if (GET_CODE (x) == REG && REGNO (x) < max_reg_before_loop | |
6195 | && INSN_UID (insn) < max_uid_for_loop | |
6196 | && uid_luid[regno_last_uid[REGNO (x)]] < uid_luid[INSN_UID (insn)]) | |
6197 | regno_last_uid[REGNO (x)] = INSN_UID (insn); | |
6198 | else | |
6199 | { | |
6200 | register int i, j; | |
6201 | register char *fmt = GET_RTX_FORMAT (GET_CODE (x)); | |
6202 | for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--) | |
6203 | { | |
6204 | if (fmt[i] == 'e') | |
6205 | update_reg_last_use (XEXP (x, i), insn); | |
6206 | else if (fmt[i] == 'E') | |
6207 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
6208 | update_reg_last_use (XVECEXP (x, i, j), insn); | |
6209 | } | |
6210 | } | |
6211 | } | |
6212 | \f | |
6213 | /* Given a jump insn JUMP, return the condition that will cause it to branch | |
6214 | to its JUMP_LABEL. If the condition cannot be understood, or is an | |
6215 | inequality floating-point comparison which needs to be reversed, 0 will | |
6216 | be returned. | |
6217 | ||
6218 | If EARLIEST is non-zero, it is a pointer to a place where the earliest | |
6219 | insn used in locating the condition was found. If a replacement test | |
6220 | of the condition is desired, it should be placed in front of that | |
6221 | insn and we will be sure that the inputs are still valid. | |
6222 | ||
6223 | The condition will be returned in a canonical form to simplify testing by | |
6224 | callers. Specifically: | |
6225 | ||
6226 | (1) The code will always be a comparison operation (EQ, NE, GT, etc.). | |
6227 | (2) Both operands will be machine operands; (cc0) will have been replaced. | |
6228 | (3) If an operand is a constant, it will be the second operand. | |
6229 | (4) (LE x const) will be replaced with (LT x <const+1>) and similarly | |
6230 | for GE, GEU, and LEU. */ | |
6231 | ||
6232 | rtx | |
6233 | get_condition (jump, earliest) | |
6234 | rtx jump; | |
6235 | rtx *earliest; | |
6236 | { | |
6237 | enum rtx_code code; | |
6238 | rtx prev = jump; | |
6239 | rtx set; | |
6240 | rtx tem; | |
6241 | rtx op0, op1; | |
6242 | int reverse_code = 0; | |
6243 | int did_reverse_condition = 0; | |
6244 | ||
6245 | /* If this is not a standard conditional jump, we can't parse it. */ | |
6246 | if (GET_CODE (jump) != JUMP_INSN | |
6247 | || ! condjump_p (jump) || simplejump_p (jump)) | |
6248 | return 0; | |
6249 | ||
6250 | code = GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 0)); | |
6251 | op0 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 0); | |
6252 | op1 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 1); | |
6253 | ||
6254 | if (earliest) | |
6255 | *earliest = jump; | |
6256 | ||
6257 | /* If this branches to JUMP_LABEL when the condition is false, reverse | |
6258 | the condition. */ | |
6259 | if (GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 2)) == LABEL_REF | |
6260 | && XEXP (XEXP (SET_SRC (PATTERN (jump)), 2), 0) == JUMP_LABEL (jump)) | |
6261 | code = reverse_condition (code), did_reverse_condition ^= 1; | |
6262 | ||
6263 | /* If we are comparing a register with zero, see if the register is set | |
6264 | in the previous insn to a COMPARE or a comparison operation. Perform | |
6265 | the same tests as a function of STORE_FLAG_VALUE as find_comparison_args | |
6266 | in cse.c */ | |
6267 | ||
6268 | while (GET_RTX_CLASS (code) == '<' && op1 == const0_rtx) | |
6269 | { | |
6270 | /* Set non-zero when we find something of interest. */ | |
6271 | rtx x = 0; | |
6272 | ||
6273 | #ifdef HAVE_cc0 | |
6274 | /* If comparison with cc0, import actual comparison from compare | |
6275 | insn. */ | |
6276 | if (op0 == cc0_rtx) | |
6277 | { | |
6278 | if ((prev = prev_nonnote_insn (prev)) == 0 | |
6279 | || GET_CODE (prev) != INSN | |
6280 | || (set = single_set (prev)) == 0 | |
6281 | || SET_DEST (set) != cc0_rtx) | |
6282 | return 0; | |
6283 | ||
6284 | op0 = SET_SRC (set); | |
6285 | op1 = CONST0_RTX (GET_MODE (op0)); | |
6286 | if (earliest) | |
6287 | *earliest = prev; | |
6288 | } | |
6289 | #endif | |
6290 | ||
6291 | /* If this is a COMPARE, pick up the two things being compared. */ | |
6292 | if (GET_CODE (op0) == COMPARE) | |
6293 | { | |
6294 | op1 = XEXP (op0, 1); | |
6295 | op0 = XEXP (op0, 0); | |
6296 | continue; | |
6297 | } | |
6298 | else if (GET_CODE (op0) != REG) | |
6299 | break; | |
6300 | ||
6301 | /* Go back to the previous insn. Stop if it is not an INSN. We also | |
6302 | stop if it isn't a single set or if it has a REG_INC note because | |
6303 | we don't want to bother dealing with it. */ | |
6304 | ||
6305 | if ((prev = prev_nonnote_insn (prev)) == 0 | |
6306 | || GET_CODE (prev) != INSN | |
6307 | || FIND_REG_INC_NOTE (prev, 0) | |
6308 | || (set = single_set (prev)) == 0) | |
6309 | break; | |
6310 | ||
6311 | /* If this is setting OP0, get what it sets it to if it looks | |
6312 | relevant. */ | |
6313 | if (SET_DEST (set) == op0) | |
6314 | { | |
6315 | enum machine_mode inner_mode = GET_MODE (SET_SRC (set)); | |
6316 | ||
6317 | if ((GET_CODE (SET_SRC (set)) == COMPARE | |
6318 | || (((code == NE | |
6319 | || (code == LT | |
6320 | && GET_MODE_CLASS (inner_mode) == MODE_INT | |
6321 | && (GET_MODE_BITSIZE (inner_mode) | |
6322 | <= HOST_BITS_PER_WIDE_INT) | |
6323 | && (STORE_FLAG_VALUE | |
6324 | & ((HOST_WIDE_INT) 1 | |
6325 | << (GET_MODE_BITSIZE (inner_mode) - 1)))) | |
6326 | #ifdef FLOAT_STORE_FLAG_VALUE | |
6327 | || (code == LT | |
6328 | && GET_MODE_CLASS (inner_mode) == MODE_FLOAT | |
6329 | && FLOAT_STORE_FLAG_VALUE < 0) | |
6330 | #endif | |
6331 | )) | |
6332 | && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<'))) | |
6333 | x = SET_SRC (set); | |
6334 | else if (((code == EQ | |
6335 | || (code == GE | |
6336 | && (GET_MODE_BITSIZE (inner_mode) | |
6337 | <= HOST_BITS_PER_WIDE_INT) | |
6338 | && GET_MODE_CLASS (inner_mode) == MODE_INT | |
6339 | && (STORE_FLAG_VALUE | |
6340 | & ((HOST_WIDE_INT) 1 | |
6341 | << (GET_MODE_BITSIZE (inner_mode) - 1)))) | |
6342 | #ifdef FLOAT_STORE_FLAG_VALUE | |
6343 | || (code == GE | |
6344 | && GET_MODE_CLASS (inner_mode) == MODE_FLOAT | |
6345 | && FLOAT_STORE_FLAG_VALUE < 0) | |
6346 | #endif | |
6347 | )) | |
6348 | && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<') | |
6349 | { | |
6350 | /* We might have reversed a LT to get a GE here. But this wasn't | |
6351 | actually the comparison of data, so we don't flag that we | |
6352 | have had to reverse the condition. */ | |
6353 | did_reverse_condition ^= 1; | |
6354 | reverse_code = 1; | |
6355 | x = SET_SRC (set); | |
6356 | } | |
6357 | } | |
6358 | ||
6359 | else if (reg_set_p (op0, prev)) | |
6360 | /* If this sets OP0, but not directly, we have to give up. */ | |
6361 | break; | |
6362 | ||
6363 | if (x) | |
6364 | { | |
6365 | if (GET_RTX_CLASS (GET_CODE (x)) == '<') | |
6366 | code = GET_CODE (x); | |
6367 | if (reverse_code) | |
6368 | { | |
6369 | code = reverse_condition (code); | |
6370 | did_reverse_condition ^= 1; | |
6371 | reverse_code = 0; | |
6372 | } | |
6373 | ||
6374 | op0 = XEXP (x, 0), op1 = XEXP (x, 1); | |
6375 | if (earliest) | |
6376 | *earliest = prev; | |
6377 | } | |
6378 | } | |
6379 | ||
6380 | /* If constant is first, put it last. */ | |
6381 | if (CONSTANT_P (op0)) | |
6382 | code = swap_condition (code), tem = op0, op0 = op1, op1 = tem; | |
6383 | ||
6384 | /* If OP0 is the result of a comparison, we weren't able to find what | |
6385 | was really being compared, so fail. */ | |
6386 | if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC) | |
6387 | return 0; | |
6388 | ||
6389 | /* Canonicalize any ordered comparison with integers involving equality | |
6390 | if we can do computations in the relevant mode and we do not | |
6391 | overflow. */ | |
6392 | ||
6393 | if (GET_CODE (op1) == CONST_INT | |
6394 | && GET_MODE (op0) != VOIDmode | |
6395 | && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT) | |
6396 | { | |
6397 | HOST_WIDE_INT const_val = INTVAL (op1); | |
6398 | unsigned HOST_WIDE_INT uconst_val = const_val; | |
6399 | unsigned HOST_WIDE_INT max_val | |
6400 | = (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0)); | |
6401 | ||
6402 | switch (code) | |
6403 | { | |
6404 | case LE: | |
6405 | if (const_val != max_val >> 1) | |
6406 | code = LT, op1 = GEN_INT (const_val + 1); | |
6407 | break; | |
6408 | ||
6409 | case GE: | |
6410 | if (const_val | |
6411 | != (((HOST_WIDE_INT) 1 | |
6412 | << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1)))) | |
6413 | code = GT, op1 = GEN_INT (const_val - 1); | |
6414 | break; | |
6415 | ||
6416 | case LEU: | |
6417 | if (uconst_val != max_val) | |
6418 | code = LTU, op1 = GEN_INT (uconst_val + 1); | |
6419 | break; | |
6420 | ||
6421 | case GEU: | |
6422 | if (uconst_val != 0) | |
6423 | code = GTU, op1 = GEN_INT (uconst_val - 1); | |
6424 | break; | |
6425 | } | |
6426 | } | |
6427 | ||
6428 | /* If this was floating-point and we reversed anything other than an | |
6429 | EQ or NE, return zero. */ | |
6430 | if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT | |
6431 | && did_reverse_condition && code != NE && code != EQ | |
6432 | && GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT) | |
6433 | return 0; | |
6434 | ||
6435 | #ifdef HAVE_cc0 | |
6436 | /* Never return CC0; return zero instead. */ | |
6437 | if (op0 == cc0_rtx) | |
6438 | return 0; | |
6439 | #endif | |
6440 | ||
6441 | return gen_rtx (code, VOIDmode, op0, op1); | |
6442 | } | |
6443 | ||
6444 | /* Similar to above routine, except that we also put an invariant last | |
6445 | unless both operands are invariants. */ | |
6446 | ||
6447 | rtx | |
6448 | get_condition_for_loop (x) | |
6449 | rtx x; | |
6450 | { | |
6451 | rtx comparison = get_condition (x, NULL_PTR); | |
6452 | ||
6453 | if (comparison == 0 | |
6454 | || ! invariant_p (XEXP (comparison, 0)) | |
6455 | || invariant_p (XEXP (comparison, 1))) | |
6456 | return comparison; | |
6457 | ||
6458 | return gen_rtx (swap_condition (GET_CODE (comparison)), VOIDmode, | |
6459 | XEXP (comparison, 1), XEXP (comparison, 0)); | |
6460 | } |