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9bf86ebb PR |
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 int basic_induction_var (); | |
270 | static rtx simplify_giv_expr (); | |
271 | static int general_induction_var (); | |
272 | static int consec_sets_giv (); | |
273 | static int check_dbra_loop (); | |
274 | static rtx express_from (); | |
275 | static int combine_givs_p (); | |
276 | static void combine_givs (); | |
277 | static int product_cheap_p (); | |
278 | static int maybe_eliminate_biv (); | |
279 | static int maybe_eliminate_biv_1 (); | |
280 | static int last_use_this_basic_block (); | |
281 | static void record_initial (); | |
282 | static void update_reg_last_use (); | |
283 | \f | |
284 | /* Relative gain of eliminating various kinds of operations. */ | |
285 | int add_cost; | |
286 | #if 0 | |
287 | int shift_cost; | |
288 | int mult_cost; | |
289 | #endif | |
290 | ||
291 | /* Benefit penalty, if a giv is not replaceable, i.e. must emit an insn to | |
292 | copy the value of the strength reduced giv to its original register. */ | |
293 | int copy_cost; | |
294 | ||
295 | void | |
296 | init_loop () | |
297 | { | |
298 | char *free_point = (char *) oballoc (1); | |
299 | rtx reg = gen_rtx (REG, word_mode, 0); | |
300 | rtx pow2 = GEN_INT (32); | |
301 | rtx lea; | |
302 | int i; | |
303 | ||
304 | add_cost = rtx_cost (gen_rtx (PLUS, word_mode, reg, reg), SET); | |
305 | ||
306 | /* We multiply by 2 to reconcile the difference in scale between | |
307 | these two ways of computing costs. Otherwise the cost of a copy | |
308 | will be far less than the cost of an add. */ | |
309 | ||
310 | copy_cost = 2 * 2; | |
311 | ||
312 | /* Free the objects we just allocated. */ | |
313 | obfree (free_point); | |
314 | ||
315 | /* Initialize the obstack used for rtl in product_cheap_p. */ | |
316 | gcc_obstack_init (&temp_obstack); | |
317 | } | |
318 | \f | |
319 | /* Entry point of this file. Perform loop optimization | |
320 | on the current function. F is the first insn of the function | |
321 | and DUMPFILE is a stream for output of a trace of actions taken | |
322 | (or 0 if none should be output). */ | |
323 | ||
324 | void | |
325 | loop_optimize (f, dumpfile) | |
326 | /* f is the first instruction of a chain of insns for one function */ | |
327 | rtx f; | |
328 | FILE *dumpfile; | |
329 | { | |
330 | register rtx insn; | |
331 | register int i; | |
332 | rtx end; | |
333 | rtx last_insn; | |
334 | ||
335 | loop_dump_stream = dumpfile; | |
336 | ||
337 | init_recog_no_volatile (); | |
338 | init_alias_analysis (); | |
339 | ||
340 | max_reg_before_loop = max_reg_num (); | |
341 | ||
342 | moved_once = (char *) alloca (max_reg_before_loop); | |
343 | bzero (moved_once, max_reg_before_loop); | |
344 | ||
345 | regs_may_share = 0; | |
346 | ||
347 | /* Count the number of loops. */ | |
348 | ||
349 | max_loop_num = 0; | |
350 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
351 | { | |
352 | if (GET_CODE (insn) == NOTE | |
353 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
354 | max_loop_num++; | |
355 | } | |
356 | ||
357 | /* Don't waste time if no loops. */ | |
358 | if (max_loop_num == 0) | |
359 | return; | |
360 | ||
361 | /* Get size to use for tables indexed by uids. | |
362 | Leave some space for labels allocated by find_and_verify_loops. */ | |
363 | max_uid_for_loop = get_max_uid () + 1 + max_loop_num * 32; | |
364 | ||
365 | uid_luid = (int *) alloca (max_uid_for_loop * sizeof (int)); | |
366 | uid_loop_num = (int *) alloca (max_uid_for_loop * sizeof (int)); | |
367 | ||
368 | bzero (uid_luid, max_uid_for_loop * sizeof (int)); | |
369 | bzero (uid_loop_num, max_uid_for_loop * sizeof (int)); | |
370 | ||
371 | /* Allocate tables for recording each loop. We set each entry, so they need | |
372 | not be zeroed. */ | |
373 | loop_number_loop_starts = (rtx *) alloca (max_loop_num * sizeof (rtx)); | |
374 | loop_number_loop_ends = (rtx *) alloca (max_loop_num * sizeof (rtx)); | |
375 | loop_outer_loop = (int *) alloca (max_loop_num * sizeof (int)); | |
376 | loop_invalid = (char *) alloca (max_loop_num * sizeof (char)); | |
377 | loop_number_exit_labels = (rtx *) alloca (max_loop_num * sizeof (rtx)); | |
378 | ||
379 | /* Find and process each loop. | |
380 | First, find them, and record them in order of their beginnings. */ | |
381 | find_and_verify_loops (f); | |
382 | ||
383 | /* Now find all register lifetimes. This must be done after | |
384 | find_and_verify_loops, because it might reorder the insns in the | |
385 | function. */ | |
386 | reg_scan (f, max_reg_num (), 1); | |
387 | ||
388 | /* See if we went too far. */ | |
389 | if (get_max_uid () > max_uid_for_loop) | |
390 | abort (); | |
391 | ||
392 | /* Compute the mapping from uids to luids. | |
393 | LUIDs are numbers assigned to insns, like uids, | |
394 | except that luids increase monotonically through the code. | |
395 | Don't assign luids to line-number NOTEs, so that the distance in luids | |
396 | between two insns is not affected by -g. */ | |
397 | ||
398 | for (insn = f, i = 0; insn; insn = NEXT_INSN (insn)) | |
399 | { | |
400 | last_insn = insn; | |
401 | if (GET_CODE (insn) != NOTE | |
402 | || NOTE_LINE_NUMBER (insn) <= 0) | |
403 | uid_luid[INSN_UID (insn)] = ++i; | |
404 | else | |
405 | /* Give a line number note the same luid as preceding insn. */ | |
406 | uid_luid[INSN_UID (insn)] = i; | |
407 | } | |
408 | ||
409 | max_luid = i + 1; | |
410 | ||
411 | /* Don't leave gaps in uid_luid for insns that have been | |
412 | deleted. It is possible that the first or last insn | |
413 | using some register has been deleted by cross-jumping. | |
414 | Make sure that uid_luid for that former insn's uid | |
415 | points to the general area where that insn used to be. */ | |
416 | for (i = 0; i < max_uid_for_loop; i++) | |
417 | { | |
418 | uid_luid[0] = uid_luid[i]; | |
419 | if (uid_luid[0] != 0) | |
420 | break; | |
421 | } | |
422 | for (i = 0; i < max_uid_for_loop; i++) | |
423 | if (uid_luid[i] == 0) | |
424 | uid_luid[i] = uid_luid[i - 1]; | |
425 | ||
426 | /* Create a mapping from loops to BLOCK tree nodes. */ | |
427 | if (flag_unroll_loops && write_symbols != NO_DEBUG) | |
428 | find_loop_tree_blocks (); | |
429 | ||
430 | /* Now scan the loops, last ones first, since this means inner ones are done | |
431 | before outer ones. */ | |
432 | for (i = max_loop_num-1; i >= 0; i--) | |
433 | if (! loop_invalid[i] && loop_number_loop_ends[i]) | |
434 | scan_loop (loop_number_loop_starts[i], loop_number_loop_ends[i], | |
435 | max_reg_num ()); | |
436 | ||
437 | /* If debugging and unrolling loops, we must replicate the tree nodes | |
438 | corresponding to the blocks inside the loop, so that the original one | |
439 | to one mapping will remain. */ | |
440 | if (flag_unroll_loops && write_symbols != NO_DEBUG) | |
441 | unroll_block_trees (); | |
442 | } | |
443 | \f | |
444 | /* Optimize one loop whose start is LOOP_START and end is END. | |
445 | LOOP_START is the NOTE_INSN_LOOP_BEG and END is the matching | |
446 | NOTE_INSN_LOOP_END. */ | |
447 | ||
448 | /* ??? Could also move memory writes out of loops if the destination address | |
449 | is invariant, the source is invariant, the memory write is not volatile, | |
450 | and if we can prove that no read inside the loop can read this address | |
451 | before the write occurs. If there is a read of this address after the | |
452 | write, then we can also mark the memory read as invariant. */ | |
453 | ||
454 | static void | |
455 | scan_loop (loop_start, end, nregs) | |
456 | rtx loop_start, end; | |
457 | int nregs; | |
458 | { | |
459 | register int i; | |
460 | register rtx p; | |
461 | /* 1 if we are scanning insns that could be executed zero times. */ | |
462 | int maybe_never = 0; | |
463 | /* 1 if we are scanning insns that might never be executed | |
464 | due to a subroutine call which might exit before they are reached. */ | |
465 | int call_passed = 0; | |
466 | /* For a rotated loop that is entered near the bottom, | |
467 | this is the label at the top. Otherwise it is zero. */ | |
468 | rtx loop_top = 0; | |
469 | /* Jump insn that enters the loop, or 0 if control drops in. */ | |
470 | rtx loop_entry_jump = 0; | |
471 | /* Place in the loop where control enters. */ | |
472 | rtx scan_start; | |
473 | /* Number of insns in the loop. */ | |
474 | int insn_count; | |
475 | int in_libcall = 0; | |
476 | int tem; | |
477 | rtx temp; | |
478 | /* The SET from an insn, if it is the only SET in the insn. */ | |
479 | rtx set, set1; | |
480 | /* Chain describing insns movable in current loop. */ | |
481 | struct movable *movables = 0; | |
482 | /* Last element in `movables' -- so we can add elements at the end. */ | |
483 | struct movable *last_movable = 0; | |
484 | /* Ratio of extra register life span we can justify | |
485 | for saving an instruction. More if loop doesn't call subroutines | |
486 | since in that case saving an insn makes more difference | |
487 | and more registers are available. */ | |
488 | int threshold; | |
489 | /* If we have calls, contains the insn in which a register was used | |
490 | if it was used exactly once; contains const0_rtx if it was used more | |
491 | than once. */ | |
492 | rtx *reg_single_usage = 0; | |
493 | ||
494 | n_times_set = (short *) alloca (nregs * sizeof (short)); | |
495 | n_times_used = (short *) alloca (nregs * sizeof (short)); | |
496 | may_not_optimize = (char *) alloca (nregs); | |
497 | ||
498 | /* Determine whether this loop starts with a jump down to a test at | |
499 | the end. This will occur for a small number of loops with a test | |
500 | that is too complex to duplicate in front of the loop. | |
501 | ||
502 | We search for the first insn or label in the loop, skipping NOTEs. | |
503 | However, we must be careful not to skip past a NOTE_INSN_LOOP_BEG | |
504 | (because we might have a loop executed only once that contains a | |
505 | loop which starts with a jump to its exit test) or a NOTE_INSN_LOOP_END | |
506 | (in case we have a degenerate loop). | |
507 | ||
508 | Note that if we mistakenly think that a loop is entered at the top | |
509 | when, in fact, it is entered at the exit test, the only effect will be | |
510 | slightly poorer optimization. Making the opposite error can generate | |
511 | incorrect code. Since very few loops now start with a jump to the | |
512 | exit test, the code here to detect that case is very conservative. */ | |
513 | ||
514 | for (p = NEXT_INSN (loop_start); | |
515 | p != end | |
516 | && GET_CODE (p) != CODE_LABEL && GET_RTX_CLASS (GET_CODE (p)) != 'i' | |
517 | && (GET_CODE (p) != NOTE | |
518 | || (NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_BEG | |
519 | && NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_END)); | |
520 | p = NEXT_INSN (p)) | |
521 | ; | |
522 | ||
523 | scan_start = p; | |
524 | ||
525 | /* Set up variables describing this loop. */ | |
526 | prescan_loop (loop_start, end); | |
527 | threshold = (loop_has_call ? 1 : 2) * (1 + n_non_fixed_regs); | |
528 | ||
529 | /* If loop has a jump before the first label, | |
530 | the true entry is the target of that jump. | |
531 | Start scan from there. | |
532 | But record in LOOP_TOP the place where the end-test jumps | |
533 | back to so we can scan that after the end of the loop. */ | |
534 | if (GET_CODE (p) == JUMP_INSN) | |
535 | { | |
536 | loop_entry_jump = p; | |
537 | ||
538 | /* Loop entry must be unconditional jump (and not a RETURN) */ | |
539 | if (simplejump_p (p) | |
540 | && JUMP_LABEL (p) != 0 | |
541 | /* Check to see whether the jump actually | |
542 | jumps out of the loop (meaning it's no loop). | |
543 | This case can happen for things like | |
544 | do {..} while (0). If this label was generated previously | |
545 | by loop, we can't tell anything about it and have to reject | |
546 | the loop. */ | |
547 | && INSN_UID (JUMP_LABEL (p)) < max_uid_for_loop | |
548 | && INSN_LUID (JUMP_LABEL (p)) >= INSN_LUID (loop_start) | |
549 | && INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (end)) | |
550 | { | |
551 | loop_top = next_label (scan_start); | |
552 | scan_start = JUMP_LABEL (p); | |
553 | } | |
554 | } | |
555 | ||
556 | /* If SCAN_START was an insn created by loop, we don't know its luid | |
557 | as required by loop_reg_used_before_p. So skip such loops. (This | |
558 | test may never be true, but it's best to play it safe.) | |
559 | ||
560 | Also, skip loops where we do not start scanning at a label. This | |
561 | test also rejects loops starting with a JUMP_INSN that failed the | |
562 | test above. */ | |
563 | ||
564 | if (INSN_UID (scan_start) >= max_uid_for_loop | |
565 | || GET_CODE (scan_start) != CODE_LABEL) | |
566 | { | |
567 | if (loop_dump_stream) | |
568 | fprintf (loop_dump_stream, "\nLoop from %d to %d is phony.\n\n", | |
569 | INSN_UID (loop_start), INSN_UID (end)); | |
570 | return; | |
571 | } | |
572 | ||
573 | /* Count number of times each reg is set during this loop. | |
574 | Set may_not_optimize[I] if it is not safe to move out | |
575 | the setting of register I. If this loop has calls, set | |
576 | reg_single_usage[I]. */ | |
577 | ||
578 | bzero (n_times_set, nregs * sizeof (short)); | |
579 | bzero (may_not_optimize, nregs); | |
580 | ||
581 | if (loop_has_call) | |
582 | { | |
583 | reg_single_usage = (rtx *) alloca (nregs * sizeof (rtx)); | |
584 | bzero (reg_single_usage, nregs * sizeof (rtx)); | |
585 | } | |
586 | ||
587 | count_loop_regs_set (loop_top ? loop_top : loop_start, end, | |
588 | may_not_optimize, reg_single_usage, &insn_count, nregs); | |
589 | ||
590 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
591 | may_not_optimize[i] = 1, n_times_set[i] = 1; | |
592 | bcopy (n_times_set, n_times_used, nregs * sizeof (short)); | |
593 | ||
594 | if (loop_dump_stream) | |
595 | { | |
596 | fprintf (loop_dump_stream, "\nLoop from %d to %d: %d real insns.\n", | |
597 | INSN_UID (loop_start), INSN_UID (end), insn_count); | |
598 | if (loop_continue) | |
599 | fprintf (loop_dump_stream, "Continue at insn %d.\n", | |
600 | INSN_UID (loop_continue)); | |
601 | } | |
602 | ||
603 | /* Scan through the loop finding insns that are safe to move. | |
604 | Set n_times_set negative for the reg being set, so that | |
605 | this reg will be considered invariant for subsequent insns. | |
606 | We consider whether subsequent insns use the reg | |
607 | in deciding whether it is worth actually moving. | |
608 | ||
609 | MAYBE_NEVER is nonzero if we have passed a conditional jump insn | |
610 | and therefore it is possible that the insns we are scanning | |
611 | would never be executed. At such times, we must make sure | |
612 | that it is safe to execute the insn once instead of zero times. | |
613 | When MAYBE_NEVER is 0, all insns will be executed at least once | |
614 | so that is not a problem. */ | |
615 | ||
616 | p = scan_start; | |
617 | while (1) | |
618 | { | |
619 | p = NEXT_INSN (p); | |
620 | /* At end of a straight-in loop, we are done. | |
621 | At end of a loop entered at the bottom, scan the top. */ | |
622 | if (p == scan_start) | |
623 | break; | |
624 | if (p == end) | |
625 | { | |
626 | if (loop_top != 0) | |
627 | p = NEXT_INSN (loop_top); | |
628 | else | |
629 | break; | |
630 | if (p == scan_start) | |
631 | break; | |
632 | } | |
633 | ||
634 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i' | |
635 | && find_reg_note (p, REG_LIBCALL, NULL_RTX)) | |
636 | in_libcall = 1; | |
637 | else if (GET_RTX_CLASS (GET_CODE (p)) == 'i' | |
638 | && find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
639 | in_libcall = 0; | |
640 | ||
641 | if (GET_CODE (p) == INSN | |
642 | && (set = single_set (p)) | |
643 | && GET_CODE (SET_DEST (set)) == REG | |
644 | && ! may_not_optimize[REGNO (SET_DEST (set))]) | |
645 | { | |
646 | int tem1 = 0; | |
647 | int tem2 = 0; | |
648 | int move_insn = 0; | |
649 | rtx src = SET_SRC (set); | |
650 | rtx dependencies = 0; | |
651 | ||
652 | /* Figure out what to use as a source of this insn. If a REG_EQUIV | |
653 | note is given or if a REG_EQUAL note with a constant operand is | |
654 | specified, use it as the source and mark that we should move | |
655 | this insn by calling emit_move_insn rather that duplicating the | |
656 | insn. | |
657 | ||
658 | Otherwise, only use the REG_EQUAL contents if a REG_RETVAL note | |
659 | is present. */ | |
660 | temp = find_reg_note (p, REG_EQUIV, NULL_RTX); | |
661 | if (temp) | |
662 | src = XEXP (temp, 0), move_insn = 1; | |
663 | else | |
664 | { | |
665 | temp = find_reg_note (p, REG_EQUAL, NULL_RTX); | |
666 | if (temp && CONSTANT_P (XEXP (temp, 0))) | |
667 | src = XEXP (temp, 0), move_insn = 1; | |
668 | if (temp && find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
669 | { | |
670 | src = XEXP (temp, 0); | |
671 | /* A libcall block can use regs that don't appear in | |
672 | the equivalent expression. To move the libcall, | |
673 | we must move those regs too. */ | |
674 | dependencies = libcall_other_reg (p, src); | |
675 | } | |
676 | } | |
677 | ||
678 | /* Don't try to optimize a register that was made | |
679 | by loop-optimization for an inner loop. | |
680 | We don't know its life-span, so we can't compute the benefit. */ | |
681 | if (REGNO (SET_DEST (set)) >= max_reg_before_loop) | |
682 | ; | |
683 | /* In order to move a register, we need to have one of three cases: | |
684 | (1) it is used only in the same basic block as the set | |
685 | (2) it is not a user variable and it is not used in the | |
686 | exit test (this can cause the variable to be used | |
687 | before it is set just like a user-variable). | |
688 | (3) the set is guaranteed to be executed once the loop starts, | |
689 | and the reg is not used until after that. */ | |
690 | else if (! ((! maybe_never | |
691 | && ! loop_reg_used_before_p (set, p, loop_start, | |
692 | scan_start, end)) | |
693 | || (! REG_USERVAR_P (SET_DEST (PATTERN (p))) | |
694 | && ! REG_LOOP_TEST_P (SET_DEST (PATTERN (p)))) | |
695 | || reg_in_basic_block_p (p, SET_DEST (PATTERN (p))))) | |
696 | ; | |
697 | else if ((tem = invariant_p (src)) | |
698 | && (dependencies == 0 | |
699 | || (tem2 = invariant_p (dependencies)) != 0) | |
700 | && (n_times_set[REGNO (SET_DEST (set))] == 1 | |
701 | || (tem1 | |
702 | = consec_sets_invariant_p (SET_DEST (set), | |
703 | n_times_set[REGNO (SET_DEST (set))], | |
704 | p))) | |
705 | /* If the insn can cause a trap (such as divide by zero), | |
706 | can't move it unless it's guaranteed to be executed | |
707 | once loop is entered. Even a function call might | |
708 | prevent the trap insn from being reached | |
709 | (since it might exit!) */ | |
710 | && ! ((maybe_never || call_passed) | |
711 | && may_trap_p (src))) | |
712 | { | |
713 | register struct movable *m; | |
714 | register int regno = REGNO (SET_DEST (set)); | |
715 | ||
716 | /* A potential lossage is where we have a case where two insns | |
717 | can be combined as long as they are both in the loop, but | |
718 | we move one of them outside the loop. For large loops, | |
719 | this can lose. The most common case of this is the address | |
720 | of a function being called. | |
721 | ||
722 | Therefore, if this register is marked as being used exactly | |
723 | once if we are in a loop with calls (a "large loop"), see if | |
724 | we can replace the usage of this register with the source | |
725 | of this SET. If we can, delete this insn. | |
726 | ||
727 | Don't do this if P has a REG_RETVAL note or if we have | |
728 | SMALL_REGISTER_CLASSES and SET_SRC is a hard register. */ | |
729 | ||
730 | if (reg_single_usage && reg_single_usage[regno] != 0 | |
731 | && reg_single_usage[regno] != const0_rtx | |
732 | && regno_first_uid[regno] == INSN_UID (p) | |
733 | && (regno_last_uid[regno] | |
734 | == INSN_UID (reg_single_usage[regno])) | |
735 | && n_times_set[REGNO (SET_DEST (set))] == 1 | |
736 | && ! side_effects_p (SET_SRC (set)) | |
737 | && ! find_reg_note (p, REG_RETVAL, NULL_RTX) | |
738 | #ifdef SMALL_REGISTER_CLASSES | |
739 | && ! (GET_CODE (SET_SRC (set)) == REG | |
740 | && REGNO (SET_SRC (set)) < FIRST_PSEUDO_REGISTER) | |
741 | #endif | |
742 | /* This test is not redundant; SET_SRC (set) might be | |
743 | a call-clobbered register and the life of REGNO | |
744 | might span a call. */ | |
745 | && ! modified_between_p (SET_SRC (set), p, | |
746 | reg_single_usage[regno]) | |
747 | && validate_replace_rtx (SET_DEST (set), SET_SRC (set), | |
748 | reg_single_usage[regno])) | |
749 | { | |
750 | /* Replace any usage in a REG_EQUAL note. */ | |
751 | REG_NOTES (reg_single_usage[regno]) | |
752 | = replace_rtx (REG_NOTES (reg_single_usage[regno]), | |
753 | SET_DEST (set), SET_SRC (set)); | |
754 | ||
755 | PUT_CODE (p, NOTE); | |
756 | NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED; | |
757 | NOTE_SOURCE_FILE (p) = 0; | |
758 | n_times_set[regno] = 0; | |
759 | continue; | |
760 | } | |
761 | ||
762 | m = (struct movable *) alloca (sizeof (struct movable)); | |
763 | m->next = 0; | |
764 | m->insn = p; | |
765 | m->set_src = src; | |
766 | m->dependencies = dependencies; | |
767 | m->set_dest = SET_DEST (set); | |
768 | m->force = 0; | |
769 | m->consec = n_times_set[REGNO (SET_DEST (set))] - 1; | |
770 | m->done = 0; | |
771 | m->forces = 0; | |
772 | m->partial = 0; | |
773 | m->move_insn = move_insn; | |
774 | m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0); | |
775 | m->savemode = VOIDmode; | |
776 | m->regno = regno; | |
777 | /* Set M->cond if either invariant_p or consec_sets_invariant_p | |
778 | returned 2 (only conditionally invariant). */ | |
779 | m->cond = ((tem | tem1 | tem2) > 1); | |
780 | m->global = (uid_luid[regno_last_uid[regno]] > INSN_LUID (end) | |
781 | || uid_luid[regno_first_uid[regno]] < INSN_LUID (loop_start)); | |
782 | m->match = 0; | |
783 | m->lifetime = (uid_luid[regno_last_uid[regno]] | |
784 | - uid_luid[regno_first_uid[regno]]); | |
785 | m->savings = n_times_used[regno]; | |
786 | if (find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
787 | m->savings += libcall_benefit (p); | |
788 | n_times_set[regno] = move_insn ? -2 : -1; | |
789 | /* Add M to the end of the chain MOVABLES. */ | |
790 | if (movables == 0) | |
791 | movables = m; | |
792 | else | |
793 | last_movable->next = m; | |
794 | last_movable = m; | |
795 | ||
796 | if (m->consec > 0) | |
797 | { | |
798 | /* Skip this insn, not checking REG_LIBCALL notes. */ | |
799 | p = NEXT_INSN (p); | |
800 | /* Skip the consecutive insns, if there are any. */ | |
801 | p = skip_consec_insns (p, m->consec); | |
802 | /* Back up to the last insn of the consecutive group. */ | |
803 | p = prev_nonnote_insn (p); | |
804 | ||
805 | /* We must now reset m->move_insn, m->is_equiv, and possibly | |
806 | m->set_src to correspond to the effects of all the | |
807 | insns. */ | |
808 | temp = find_reg_note (p, REG_EQUIV, NULL_RTX); | |
809 | if (temp) | |
810 | m->set_src = XEXP (temp, 0), m->move_insn = 1; | |
811 | else | |
812 | { | |
813 | temp = find_reg_note (p, REG_EQUAL, NULL_RTX); | |
814 | if (temp && CONSTANT_P (XEXP (temp, 0))) | |
815 | m->set_src = XEXP (temp, 0), m->move_insn = 1; | |
816 | else | |
817 | m->move_insn = 0; | |
818 | ||
819 | } | |
820 | m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0); | |
821 | } | |
822 | } | |
823 | /* If this register is always set within a STRICT_LOW_PART | |
824 | or set to zero, then its high bytes are constant. | |
825 | So clear them outside the loop and within the loop | |
826 | just load the low bytes. | |
827 | We must check that the machine has an instruction to do so. | |
828 | Also, if the value loaded into the register | |
829 | depends on the same register, this cannot be done. */ | |
830 | else if (SET_SRC (set) == const0_rtx | |
831 | && GET_CODE (NEXT_INSN (p)) == INSN | |
832 | && (set1 = single_set (NEXT_INSN (p))) | |
833 | && GET_CODE (set1) == SET | |
834 | && (GET_CODE (SET_DEST (set1)) == STRICT_LOW_PART) | |
835 | && (GET_CODE (XEXP (SET_DEST (set1), 0)) == SUBREG) | |
836 | && (SUBREG_REG (XEXP (SET_DEST (set1), 0)) | |
837 | == SET_DEST (set)) | |
838 | && !reg_mentioned_p (SET_DEST (set), SET_SRC (set1))) | |
839 | { | |
840 | register int regno = REGNO (SET_DEST (set)); | |
841 | if (n_times_set[regno] == 2) | |
842 | { | |
843 | register struct movable *m; | |
844 | m = (struct movable *) alloca (sizeof (struct movable)); | |
845 | m->next = 0; | |
846 | m->insn = p; | |
847 | m->set_dest = SET_DEST (set); | |
848 | m->dependencies = 0; | |
849 | m->force = 0; | |
850 | m->consec = 0; | |
851 | m->done = 0; | |
852 | m->forces = 0; | |
853 | m->move_insn = 0; | |
854 | m->partial = 1; | |
855 | /* If the insn may not be executed on some cycles, | |
856 | we can't clear the whole reg; clear just high part. | |
857 | Not even if the reg is used only within this loop. | |
858 | Consider this: | |
859 | while (1) | |
860 | while (s != t) { | |
861 | if (foo ()) x = *s; | |
862 | use (x); | |
863 | } | |
864 | Clearing x before the inner loop could clobber a value | |
865 | being saved from the last time around the outer loop. | |
866 | However, if the reg is not used outside this loop | |
867 | and all uses of the register are in the same | |
868 | basic block as the store, there is no problem. | |
869 | ||
870 | If this insn was made by loop, we don't know its | |
871 | INSN_LUID and hence must make a conservative | |
872 | assumption. */ | |
873 | m->global = (INSN_UID (p) >= max_uid_for_loop | |
874 | || (uid_luid[regno_last_uid[regno]] | |
875 | > INSN_LUID (end)) | |
876 | || (uid_luid[regno_first_uid[regno]] | |
877 | < INSN_LUID (p)) | |
878 | || (labels_in_range_p | |
879 | (p, uid_luid[regno_first_uid[regno]]))); | |
880 | if (maybe_never && m->global) | |
881 | m->savemode = GET_MODE (SET_SRC (set1)); | |
882 | else | |
883 | m->savemode = VOIDmode; | |
884 | m->regno = regno; | |
885 | m->cond = 0; | |
886 | m->match = 0; | |
887 | m->lifetime = (uid_luid[regno_last_uid[regno]] | |
888 | - uid_luid[regno_first_uid[regno]]); | |
889 | m->savings = 1; | |
890 | n_times_set[regno] = -1; | |
891 | /* Add M to the end of the chain MOVABLES. */ | |
892 | if (movables == 0) | |
893 | movables = m; | |
894 | else | |
895 | last_movable->next = m; | |
896 | last_movable = m; | |
897 | } | |
898 | } | |
899 | } | |
900 | /* Past a call insn, we get to insns which might not be executed | |
901 | because the call might exit. This matters for insns that trap. | |
902 | Call insns inside a REG_LIBCALL/REG_RETVAL block always return, | |
903 | so they don't count. */ | |
904 | else if (GET_CODE (p) == CALL_INSN && ! in_libcall) | |
905 | call_passed = 1; | |
906 | /* Past a label or a jump, we get to insns for which we | |
907 | can't count on whether or how many times they will be | |
908 | executed during each iteration. Therefore, we can | |
909 | only move out sets of trivial variables | |
910 | (those not used after the loop). */ | |
911 | /* This code appears in three places, once in scan_loop, and twice | |
912 | in strength_reduce. */ | |
913 | else if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) | |
914 | /* If we enter the loop in the middle, and scan around to the | |
915 | beginning, don't set maybe_never for that. This must be an | |
916 | unconditional jump, otherwise the code at the top of the | |
917 | loop might never be executed. Unconditional jumps are | |
918 | followed a by barrier then loop end. */ | |
919 | && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top | |
920 | && NEXT_INSN (NEXT_INSN (p)) == end | |
921 | && simplejump_p (p))) | |
922 | maybe_never = 1; | |
923 | /* At the virtual top of a converted loop, insns are again known to | |
924 | be executed: logically, the loop begins here even though the exit | |
925 | code has been duplicated. */ | |
926 | else if (GET_CODE (p) == NOTE | |
927 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP) | |
928 | maybe_never = call_passed = 0; | |
929 | } | |
930 | ||
931 | /* If one movable subsumes another, ignore that other. */ | |
932 | ||
933 | ignore_some_movables (movables); | |
934 | ||
935 | /* For each movable insn, see if the reg that it loads | |
936 | leads when it dies right into another conditionally movable insn. | |
937 | If so, record that the second insn "forces" the first one, | |
938 | since the second can be moved only if the first is. */ | |
939 | ||
940 | force_movables (movables); | |
941 | ||
942 | /* See if there are multiple movable insns that load the same value. | |
943 | If there are, make all but the first point at the first one | |
944 | through the `match' field, and add the priorities of them | |
945 | all together as the priority of the first. */ | |
946 | ||
947 | combine_movables (movables, nregs); | |
948 | ||
949 | /* Now consider each movable insn to decide whether it is worth moving. | |
950 | Store 0 in n_times_set for each reg that is moved. */ | |
951 | ||
952 | move_movables (movables, threshold, | |
953 | insn_count, loop_start, end, nregs); | |
954 | ||
955 | /* Now candidates that still are negative are those not moved. | |
956 | Change n_times_set to indicate that those are not actually invariant. */ | |
957 | for (i = 0; i < nregs; i++) | |
958 | if (n_times_set[i] < 0) | |
959 | n_times_set[i] = n_times_used[i]; | |
960 | ||
961 | if (flag_strength_reduce) | |
962 | strength_reduce (scan_start, end, loop_top, | |
963 | insn_count, loop_start, end); | |
964 | } | |
965 | \f | |
966 | /* Add elements to *OUTPUT to record all the pseudo-regs | |
967 | mentioned in IN_THIS but not mentioned in NOT_IN_THIS. */ | |
968 | ||
969 | void | |
970 | record_excess_regs (in_this, not_in_this, output) | |
971 | rtx in_this, not_in_this; | |
972 | rtx *output; | |
973 | { | |
974 | enum rtx_code code; | |
975 | char *fmt; | |
976 | int i; | |
977 | ||
978 | code = GET_CODE (in_this); | |
979 | ||
980 | switch (code) | |
981 | { | |
982 | case PC: | |
983 | case CC0: | |
984 | case CONST_INT: | |
985 | case CONST_DOUBLE: | |
986 | case CONST: | |
987 | case SYMBOL_REF: | |
988 | case LABEL_REF: | |
989 | return; | |
990 | ||
991 | case REG: | |
992 | if (REGNO (in_this) >= FIRST_PSEUDO_REGISTER | |
993 | && ! reg_mentioned_p (in_this, not_in_this)) | |
994 | *output = gen_rtx (EXPR_LIST, VOIDmode, in_this, *output); | |
995 | return; | |
996 | } | |
997 | ||
998 | fmt = GET_RTX_FORMAT (code); | |
999 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1000 | { | |
1001 | int j; | |
1002 | ||
1003 | switch (fmt[i]) | |
1004 | { | |
1005 | case 'E': | |
1006 | for (j = 0; j < XVECLEN (in_this, i); j++) | |
1007 | record_excess_regs (XVECEXP (in_this, i, j), not_in_this, output); | |
1008 | break; | |
1009 | ||
1010 | case 'e': | |
1011 | record_excess_regs (XEXP (in_this, i), not_in_this, output); | |
1012 | break; | |
1013 | } | |
1014 | } | |
1015 | } | |
1016 | \f | |
1017 | /* Check what regs are referred to in the libcall block ending with INSN, | |
1018 | aside from those mentioned in the equivalent value. | |
1019 | If there are none, return 0. | |
1020 | If there are one or more, return an EXPR_LIST containing all of them. */ | |
1021 | ||
1022 | static rtx | |
1023 | libcall_other_reg (insn, equiv) | |
1024 | rtx insn, equiv; | |
1025 | { | |
1026 | rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX); | |
1027 | rtx p = XEXP (note, 0); | |
1028 | rtx output = 0; | |
1029 | ||
1030 | /* First, find all the regs used in the libcall block | |
1031 | that are not mentioned as inputs to the result. */ | |
1032 | ||
1033 | while (p != insn) | |
1034 | { | |
1035 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
1036 | || GET_CODE (p) == CALL_INSN) | |
1037 | record_excess_regs (PATTERN (p), equiv, &output); | |
1038 | p = NEXT_INSN (p); | |
1039 | } | |
1040 | ||
1041 | return output; | |
1042 | } | |
1043 | \f | |
1044 | /* Return 1 if all uses of REG | |
1045 | are between INSN and the end of the basic block. */ | |
1046 | ||
1047 | static int | |
1048 | reg_in_basic_block_p (insn, reg) | |
1049 | rtx insn, reg; | |
1050 | { | |
1051 | int regno = REGNO (reg); | |
1052 | rtx p; | |
1053 | ||
1054 | if (regno_first_uid[regno] != INSN_UID (insn)) | |
1055 | return 0; | |
1056 | ||
1057 | /* Search this basic block for the already recorded last use of the reg. */ | |
1058 | for (p = insn; p; p = NEXT_INSN (p)) | |
1059 | { | |
1060 | switch (GET_CODE (p)) | |
1061 | { | |
1062 | case NOTE: | |
1063 | break; | |
1064 | ||
1065 | case INSN: | |
1066 | case CALL_INSN: | |
1067 | /* Ordinary insn: if this is the last use, we win. */ | |
1068 | if (regno_last_uid[regno] == INSN_UID (p)) | |
1069 | return 1; | |
1070 | break; | |
1071 | ||
1072 | case JUMP_INSN: | |
1073 | /* Jump insn: if this is the last use, we win. */ | |
1074 | if (regno_last_uid[regno] == INSN_UID (p)) | |
1075 | return 1; | |
1076 | /* Otherwise, it's the end of the basic block, so we lose. */ | |
1077 | return 0; | |
1078 | ||
1079 | case CODE_LABEL: | |
1080 | case BARRIER: | |
1081 | /* It's the end of the basic block, so we lose. */ | |
1082 | return 0; | |
1083 | } | |
1084 | } | |
1085 | ||
1086 | /* The "last use" doesn't follow the "first use"?? */ | |
1087 | abort (); | |
1088 | } | |
1089 | \f | |
1090 | /* Compute the benefit of eliminating the insns in the block whose | |
1091 | last insn is LAST. This may be a group of insns used to compute a | |
1092 | value directly or can contain a library call. */ | |
1093 | ||
1094 | static int | |
1095 | libcall_benefit (last) | |
1096 | rtx last; | |
1097 | { | |
1098 | rtx insn; | |
1099 | int benefit = 0; | |
1100 | ||
1101 | for (insn = XEXP (find_reg_note (last, REG_RETVAL, NULL_RTX), 0); | |
1102 | insn != last; insn = NEXT_INSN (insn)) | |
1103 | { | |
1104 | if (GET_CODE (insn) == CALL_INSN) | |
1105 | benefit += 10; /* Assume at least this many insns in a library | |
1106 | routine. */ | |
1107 | else if (GET_CODE (insn) == INSN | |
1108 | && GET_CODE (PATTERN (insn)) != USE | |
1109 | && GET_CODE (PATTERN (insn)) != CLOBBER) | |
1110 | benefit++; | |
1111 | } | |
1112 | ||
1113 | return benefit; | |
1114 | } | |
1115 | \f | |
1116 | /* Skip COUNT insns from INSN, counting library calls as 1 insn. */ | |
1117 | ||
1118 | static rtx | |
1119 | skip_consec_insns (insn, count) | |
1120 | rtx insn; | |
1121 | int count; | |
1122 | { | |
1123 | for (; count > 0; count--) | |
1124 | { | |
1125 | rtx temp; | |
1126 | ||
1127 | /* If first insn of libcall sequence, skip to end. */ | |
1128 | /* Do this at start of loop, since INSN is guaranteed to | |
1129 | be an insn here. */ | |
1130 | if (GET_CODE (insn) != NOTE | |
1131 | && (temp = find_reg_note (insn, REG_LIBCALL, NULL_RTX))) | |
1132 | insn = XEXP (temp, 0); | |
1133 | ||
1134 | do insn = NEXT_INSN (insn); | |
1135 | while (GET_CODE (insn) == NOTE); | |
1136 | } | |
1137 | ||
1138 | return insn; | |
1139 | } | |
1140 | ||
1141 | /* Ignore any movable whose insn falls within a libcall | |
1142 | which is part of another movable. | |
1143 | We make use of the fact that the movable for the libcall value | |
1144 | was made later and so appears later on the chain. */ | |
1145 | ||
1146 | static void | |
1147 | ignore_some_movables (movables) | |
1148 | struct movable *movables; | |
1149 | { | |
1150 | register struct movable *m, *m1; | |
1151 | ||
1152 | for (m = movables; m; m = m->next) | |
1153 | { | |
1154 | /* Is this a movable for the value of a libcall? */ | |
1155 | rtx note = find_reg_note (m->insn, REG_RETVAL, NULL_RTX); | |
1156 | if (note) | |
1157 | { | |
1158 | rtx insn; | |
1159 | /* Check for earlier movables inside that range, | |
1160 | and mark them invalid. We cannot use LUIDs here because | |
1161 | insns created by loop.c for prior loops don't have LUIDs. | |
1162 | Rather than reject all such insns from movables, we just | |
1163 | explicitly check each insn in the libcall (since invariant | |
1164 | libcalls aren't that common). */ | |
1165 | for (insn = XEXP (note, 0); insn != m->insn; insn = NEXT_INSN (insn)) | |
1166 | for (m1 = movables; m1 != m; m1 = m1->next) | |
1167 | if (m1->insn == insn) | |
1168 | m1->done = 1; | |
1169 | } | |
1170 | } | |
1171 | } | |
1172 | ||
1173 | /* For each movable insn, see if the reg that it loads | |
1174 | leads when it dies right into another conditionally movable insn. | |
1175 | If so, record that the second insn "forces" the first one, | |
1176 | since the second can be moved only if the first is. */ | |
1177 | ||
1178 | static void | |
1179 | force_movables (movables) | |
1180 | struct movable *movables; | |
1181 | { | |
1182 | register struct movable *m, *m1; | |
1183 | for (m1 = movables; m1; m1 = m1->next) | |
1184 | /* Omit this if moving just the (SET (REG) 0) of a zero-extend. */ | |
1185 | if (!m1->partial && !m1->done) | |
1186 | { | |
1187 | int regno = m1->regno; | |
1188 | for (m = m1->next; m; m = m->next) | |
1189 | /* ??? Could this be a bug? What if CSE caused the | |
1190 | register of M1 to be used after this insn? | |
1191 | Since CSE does not update regno_last_uid, | |
1192 | this insn M->insn might not be where it dies. | |
1193 | But very likely this doesn't matter; what matters is | |
1194 | that M's reg is computed from M1's reg. */ | |
1195 | if (INSN_UID (m->insn) == regno_last_uid[regno] | |
1196 | && !m->done) | |
1197 | break; | |
1198 | if (m != 0 && m->set_src == m1->set_dest | |
1199 | /* If m->consec, m->set_src isn't valid. */ | |
1200 | && m->consec == 0) | |
1201 | m = 0; | |
1202 | ||
1203 | /* Increase the priority of the moving the first insn | |
1204 | since it permits the second to be moved as well. */ | |
1205 | if (m != 0) | |
1206 | { | |
1207 | m->forces = m1; | |
1208 | m1->lifetime += m->lifetime; | |
1209 | m1->savings += m1->savings; | |
1210 | } | |
1211 | } | |
1212 | } | |
1213 | \f | |
1214 | /* Find invariant expressions that are equal and can be combined into | |
1215 | one register. */ | |
1216 | ||
1217 | static void | |
1218 | combine_movables (movables, nregs) | |
1219 | struct movable *movables; | |
1220 | int nregs; | |
1221 | { | |
1222 | register struct movable *m; | |
1223 | char *matched_regs = (char *) alloca (nregs); | |
1224 | enum machine_mode mode; | |
1225 | ||
1226 | /* Regs that are set more than once are not allowed to match | |
1227 | or be matched. I'm no longer sure why not. */ | |
1228 | /* Perhaps testing m->consec_sets would be more appropriate here? */ | |
1229 | ||
1230 | for (m = movables; m; m = m->next) | |
1231 | if (m->match == 0 && n_times_used[m->regno] == 1 && !m->partial) | |
1232 | { | |
1233 | register struct movable *m1; | |
1234 | int regno = m->regno; | |
1235 | rtx reg_note, reg_note1; | |
1236 | ||
1237 | bzero (matched_regs, nregs); | |
1238 | matched_regs[regno] = 1; | |
1239 | ||
1240 | for (m1 = movables; m1; m1 = m1->next) | |
1241 | if (m != m1 && m1->match == 0 && n_times_used[m1->regno] == 1 | |
1242 | /* A reg used outside the loop mustn't be eliminated. */ | |
1243 | && !m1->global | |
1244 | /* A reg used for zero-extending mustn't be eliminated. */ | |
1245 | && !m1->partial | |
1246 | && (matched_regs[m1->regno] | |
1247 | || | |
1248 | ( | |
1249 | /* Can combine regs with different modes loaded from the | |
1250 | same constant only if the modes are the same or | |
1251 | if both are integer modes with M wider or the same | |
1252 | width as M1. The check for integer is redundant, but | |
1253 | safe, since the only case of differing destination | |
1254 | modes with equal sources is when both sources are | |
1255 | VOIDmode, i.e., CONST_INT. */ | |
1256 | (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest) | |
1257 | || (GET_MODE_CLASS (GET_MODE (m->set_dest)) == MODE_INT | |
1258 | && GET_MODE_CLASS (GET_MODE (m1->set_dest)) == MODE_INT | |
1259 | && (GET_MODE_BITSIZE (GET_MODE (m->set_dest)) | |
1260 | >= GET_MODE_BITSIZE (GET_MODE (m1->set_dest))))) | |
1261 | /* See if the source of M1 says it matches M. */ | |
1262 | && ((GET_CODE (m1->set_src) == REG | |
1263 | && matched_regs[REGNO (m1->set_src)]) | |
1264 | || rtx_equal_for_loop_p (m->set_src, m1->set_src, | |
1265 | movables)))) | |
1266 | && ((m->dependencies == m1->dependencies) | |
1267 | || rtx_equal_p (m->dependencies, m1->dependencies))) | |
1268 | { | |
1269 | m->lifetime += m1->lifetime; | |
1270 | m->savings += m1->savings; | |
1271 | m1->done = 1; | |
1272 | m1->match = m; | |
1273 | matched_regs[m1->regno] = 1; | |
1274 | } | |
1275 | } | |
1276 | ||
1277 | /* Now combine the regs used for zero-extension. | |
1278 | This can be done for those not marked `global' | |
1279 | provided their lives don't overlap. */ | |
1280 | ||
1281 | for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode; | |
1282 | mode = GET_MODE_WIDER_MODE (mode)) | |
1283 | { | |
1284 | register struct movable *m0 = 0; | |
1285 | ||
1286 | /* Combine all the registers for extension from mode MODE. | |
1287 | Don't combine any that are used outside this loop. */ | |
1288 | for (m = movables; m; m = m->next) | |
1289 | if (m->partial && ! m->global | |
1290 | && mode == GET_MODE (SET_SRC (PATTERN (NEXT_INSN (m->insn))))) | |
1291 | { | |
1292 | register struct movable *m1; | |
1293 | int first = uid_luid[regno_first_uid[m->regno]]; | |
1294 | int last = uid_luid[regno_last_uid[m->regno]]; | |
1295 | ||
1296 | if (m0 == 0) | |
1297 | { | |
1298 | /* First one: don't check for overlap, just record it. */ | |
1299 | m0 = m; | |
1300 | continue; | |
1301 | } | |
1302 | ||
1303 | /* Make sure they extend to the same mode. | |
1304 | (Almost always true.) */ | |
1305 | if (GET_MODE (m->set_dest) != GET_MODE (m0->set_dest)) | |
1306 | continue; | |
1307 | ||
1308 | /* We already have one: check for overlap with those | |
1309 | already combined together. */ | |
1310 | for (m1 = movables; m1 != m; m1 = m1->next) | |
1311 | if (m1 == m0 || (m1->partial && m1->match == m0)) | |
1312 | if (! (uid_luid[regno_first_uid[m1->regno]] > last | |
1313 | || uid_luid[regno_last_uid[m1->regno]] < first)) | |
1314 | goto overlap; | |
1315 | ||
1316 | /* No overlap: we can combine this with the others. */ | |
1317 | m0->lifetime += m->lifetime; | |
1318 | m0->savings += m->savings; | |
1319 | m->done = 1; | |
1320 | m->match = m0; | |
1321 | ||
1322 | overlap: ; | |
1323 | } | |
1324 | } | |
1325 | } | |
1326 | \f | |
1327 | /* Return 1 if regs X and Y will become the same if moved. */ | |
1328 | ||
1329 | static int | |
1330 | regs_match_p (x, y, movables) | |
1331 | rtx x, y; | |
1332 | struct movable *movables; | |
1333 | { | |
1334 | int xn = REGNO (x); | |
1335 | int yn = REGNO (y); | |
1336 | struct movable *mx, *my; | |
1337 | ||
1338 | for (mx = movables; mx; mx = mx->next) | |
1339 | if (mx->regno == xn) | |
1340 | break; | |
1341 | ||
1342 | for (my = movables; my; my = my->next) | |
1343 | if (my->regno == yn) | |
1344 | break; | |
1345 | ||
1346 | return (mx && my | |
1347 | && ((mx->match == my->match && mx->match != 0) | |
1348 | || mx->match == my | |
1349 | || mx == my->match)); | |
1350 | } | |
1351 | ||
1352 | /* Return 1 if X and Y are identical-looking rtx's. | |
1353 | This is the Lisp function EQUAL for rtx arguments. | |
1354 | ||
1355 | If two registers are matching movables or a movable register and an | |
1356 | equivalent constant, consider them equal. */ | |
1357 | ||
1358 | static int | |
1359 | rtx_equal_for_loop_p (x, y, movables) | |
1360 | rtx x, y; | |
1361 | struct movable *movables; | |
1362 | { | |
1363 | register int i; | |
1364 | register int j; | |
1365 | register struct movable *m; | |
1366 | register enum rtx_code code; | |
1367 | register char *fmt; | |
1368 | ||
1369 | if (x == y) | |
1370 | return 1; | |
1371 | if (x == 0 || y == 0) | |
1372 | return 0; | |
1373 | ||
1374 | code = GET_CODE (x); | |
1375 | ||
1376 | /* If we have a register and a constant, they may sometimes be | |
1377 | equal. */ | |
1378 | if (GET_CODE (x) == REG && n_times_set[REGNO (x)] == -2 | |
1379 | && CONSTANT_P (y)) | |
1380 | for (m = movables; m; m = m->next) | |
1381 | if (m->move_insn && m->regno == REGNO (x) | |
1382 | && rtx_equal_p (m->set_src, y)) | |
1383 | return 1; | |
1384 | ||
1385 | else if (GET_CODE (y) == REG && n_times_set[REGNO (y)] == -2 | |
1386 | && CONSTANT_P (x)) | |
1387 | for (m = movables; m; m = m->next) | |
1388 | if (m->move_insn && m->regno == REGNO (y) | |
1389 | && rtx_equal_p (m->set_src, x)) | |
1390 | return 1; | |
1391 | ||
1392 | /* Otherwise, rtx's of different codes cannot be equal. */ | |
1393 | if (code != GET_CODE (y)) | |
1394 | return 0; | |
1395 | ||
1396 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. | |
1397 | (REG:SI x) and (REG:HI x) are NOT equivalent. */ | |
1398 | ||
1399 | if (GET_MODE (x) != GET_MODE (y)) | |
1400 | return 0; | |
1401 | ||
1402 | /* These three types of rtx's can be compared nonrecursively. */ | |
1403 | if (code == REG) | |
1404 | return (REGNO (x) == REGNO (y) || regs_match_p (x, y, movables)); | |
1405 | ||
1406 | if (code == LABEL_REF) | |
1407 | return XEXP (x, 0) == XEXP (y, 0); | |
1408 | if (code == SYMBOL_REF) | |
1409 | return XSTR (x, 0) == XSTR (y, 0); | |
1410 | ||
1411 | /* Compare the elements. If any pair of corresponding elements | |
1412 | fail to match, return 0 for the whole things. */ | |
1413 | ||
1414 | fmt = GET_RTX_FORMAT (code); | |
1415 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1416 | { | |
1417 | switch (fmt[i]) | |
1418 | { | |
1419 | case 'w': | |
1420 | if (XWINT (x, i) != XWINT (y, i)) | |
1421 | return 0; | |
1422 | break; | |
1423 | ||
1424 | case 'i': | |
1425 | if (XINT (x, i) != XINT (y, i)) | |
1426 | return 0; | |
1427 | break; | |
1428 | ||
1429 | case 'E': | |
1430 | /* Two vectors must have the same length. */ | |
1431 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1432 | return 0; | |
1433 | ||
1434 | /* And the corresponding elements must match. */ | |
1435 | for (j = 0; j < XVECLEN (x, i); j++) | |
1436 | if (rtx_equal_for_loop_p (XVECEXP (x, i, j), XVECEXP (y, i, j), movables) == 0) | |
1437 | return 0; | |
1438 | break; | |
1439 | ||
1440 | case 'e': | |
1441 | if (rtx_equal_for_loop_p (XEXP (x, i), XEXP (y, i), movables) == 0) | |
1442 | return 0; | |
1443 | break; | |
1444 | ||
1445 | case 's': | |
1446 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1447 | return 0; | |
1448 | break; | |
1449 | ||
1450 | case 'u': | |
1451 | /* These are just backpointers, so they don't matter. */ | |
1452 | break; | |
1453 | ||
1454 | case '0': | |
1455 | break; | |
1456 | ||
1457 | /* It is believed that rtx's at this level will never | |
1458 | contain anything but integers and other rtx's, | |
1459 | except for within LABEL_REFs and SYMBOL_REFs. */ | |
1460 | default: | |
1461 | abort (); | |
1462 | } | |
1463 | } | |
1464 | return 1; | |
1465 | } | |
1466 | \f | |
1467 | /* If X contains any LABEL_REF's, add REG_LABEL notes for them to all | |
1468 | insns in INSNS which use thet reference. */ | |
1469 | ||
1470 | static void | |
1471 | add_label_notes (x, insns) | |
1472 | rtx x; | |
1473 | rtx insns; | |
1474 | { | |
1475 | enum rtx_code code = GET_CODE (x); | |
1476 | int i, j; | |
1477 | char *fmt; | |
1478 | rtx insn; | |
1479 | ||
1480 | if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x)) | |
1481 | { | |
1482 | rtx next = next_real_insn (XEXP (x, 0)); | |
1483 | ||
1484 | /* Don't record labels that refer to dispatch tables. | |
1485 | This is not necessary, since the tablejump references the same label. | |
1486 | And if we did record them, flow.c would make worse code. */ | |
1487 | if (next == 0 | |
1488 | || ! (GET_CODE (next) == JUMP_INSN | |
1489 | && (GET_CODE (PATTERN (next)) == ADDR_VEC | |
1490 | || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))) | |
1491 | { | |
1492 | for (insn = insns; insn; insn = NEXT_INSN (insn)) | |
1493 | if (reg_mentioned_p (XEXP (x, 0), insn)) | |
1494 | REG_NOTES (insn) = gen_rtx (EXPR_LIST, REG_LABEL, XEXP (x, 0), | |
1495 | REG_NOTES (insn)); | |
1496 | } | |
1497 | return; | |
1498 | } | |
1499 | ||
1500 | fmt = GET_RTX_FORMAT (code); | |
1501 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1502 | { | |
1503 | if (fmt[i] == 'e') | |
1504 | add_label_notes (XEXP (x, i), insns); | |
1505 | else if (fmt[i] == 'E') | |
1506 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
1507 | add_label_notes (XVECEXP (x, i, j), insns); | |
1508 | } | |
1509 | } | |
1510 | \f | |
1511 | /* Scan MOVABLES, and move the insns that deserve to be moved. | |
1512 | If two matching movables are combined, replace one reg with the | |
1513 | other throughout. */ | |
1514 | ||
1515 | static void | |
1516 | move_movables (movables, threshold, insn_count, loop_start, end, nregs) | |
1517 | struct movable *movables; | |
1518 | int threshold; | |
1519 | int insn_count; | |
1520 | rtx loop_start; | |
1521 | rtx end; | |
1522 | int nregs; | |
1523 | { | |
1524 | rtx new_start = 0; | |
1525 | register struct movable *m; | |
1526 | register rtx p; | |
1527 | /* Map of pseudo-register replacements to handle combining | |
1528 | when we move several insns that load the same value | |
1529 | into different pseudo-registers. */ | |
1530 | rtx *reg_map = (rtx *) alloca (nregs * sizeof (rtx)); | |
1531 | char *already_moved = (char *) alloca (nregs); | |
1532 | ||
1533 | bzero (already_moved, nregs); | |
1534 | bzero (reg_map, nregs * sizeof (rtx)); | |
1535 | ||
1536 | num_movables = 0; | |
1537 | ||
1538 | for (m = movables; m; m = m->next) | |
1539 | { | |
1540 | /* Describe this movable insn. */ | |
1541 | ||
1542 | if (loop_dump_stream) | |
1543 | { | |
1544 | fprintf (loop_dump_stream, "Insn %d: regno %d (life %d), ", | |
1545 | INSN_UID (m->insn), m->regno, m->lifetime); | |
1546 | if (m->consec > 0) | |
1547 | fprintf (loop_dump_stream, "consec %d, ", m->consec); | |
1548 | if (m->cond) | |
1549 | fprintf (loop_dump_stream, "cond "); | |
1550 | if (m->force) | |
1551 | fprintf (loop_dump_stream, "force "); | |
1552 | if (m->global) | |
1553 | fprintf (loop_dump_stream, "global "); | |
1554 | if (m->done) | |
1555 | fprintf (loop_dump_stream, "done "); | |
1556 | if (m->move_insn) | |
1557 | fprintf (loop_dump_stream, "move-insn "); | |
1558 | if (m->match) | |
1559 | fprintf (loop_dump_stream, "matches %d ", | |
1560 | INSN_UID (m->match->insn)); | |
1561 | if (m->forces) | |
1562 | fprintf (loop_dump_stream, "forces %d ", | |
1563 | INSN_UID (m->forces->insn)); | |
1564 | } | |
1565 | ||
1566 | /* Count movables. Value used in heuristics in strength_reduce. */ | |
1567 | num_movables++; | |
1568 | ||
1569 | /* Ignore the insn if it's already done (it matched something else). | |
1570 | Otherwise, see if it is now safe to move. */ | |
1571 | ||
1572 | if (!m->done | |
1573 | && (! m->cond | |
1574 | || (1 == invariant_p (m->set_src) | |
1575 | && (m->dependencies == 0 | |
1576 | || 1 == invariant_p (m->dependencies)) | |
1577 | && (m->consec == 0 | |
1578 | || 1 == consec_sets_invariant_p (m->set_dest, | |
1579 | m->consec + 1, | |
1580 | m->insn)))) | |
1581 | && (! m->forces || m->forces->done)) | |
1582 | { | |
1583 | register int regno; | |
1584 | register rtx p; | |
1585 | int savings = m->savings; | |
1586 | ||
1587 | /* We have an insn that is safe to move. | |
1588 | Compute its desirability. */ | |
1589 | ||
1590 | p = m->insn; | |
1591 | regno = m->regno; | |
1592 | ||
1593 | if (loop_dump_stream) | |
1594 | fprintf (loop_dump_stream, "savings %d ", savings); | |
1595 | ||
1596 | if (moved_once[regno]) | |
1597 | { | |
1598 | insn_count *= 2; | |
1599 | ||
1600 | if (loop_dump_stream) | |
1601 | fprintf (loop_dump_stream, "halved since already moved "); | |
1602 | } | |
1603 | ||
1604 | /* An insn MUST be moved if we already moved something else | |
1605 | which is safe only if this one is moved too: that is, | |
1606 | if already_moved[REGNO] is nonzero. */ | |
1607 | ||
1608 | /* An insn is desirable to move if the new lifetime of the | |
1609 | register is no more than THRESHOLD times the old lifetime. | |
1610 | If it's not desirable, it means the loop is so big | |
1611 | that moving won't speed things up much, | |
1612 | and it is liable to make register usage worse. */ | |
1613 | ||
1614 | /* It is also desirable to move if it can be moved at no | |
1615 | extra cost because something else was already moved. */ | |
1616 | ||
1617 | if (already_moved[regno] | |
1618 | || (threshold * savings * m->lifetime) >= insn_count | |
1619 | || (m->forces && m->forces->done | |
1620 | && n_times_used[m->forces->regno] == 1)) | |
1621 | { | |
1622 | int count; | |
1623 | register struct movable *m1; | |
1624 | rtx first; | |
1625 | ||
1626 | /* Now move the insns that set the reg. */ | |
1627 | ||
1628 | if (m->partial && m->match) | |
1629 | { | |
1630 | rtx newpat, i1; | |
1631 | rtx r1, r2; | |
1632 | /* Find the end of this chain of matching regs. | |
1633 | Thus, we load each reg in the chain from that one reg. | |
1634 | And that reg is loaded with 0 directly, | |
1635 | since it has ->match == 0. */ | |
1636 | for (m1 = m; m1->match; m1 = m1->match); | |
1637 | newpat = gen_move_insn (SET_DEST (PATTERN (m->insn)), | |
1638 | SET_DEST (PATTERN (m1->insn))); | |
1639 | i1 = emit_insn_before (newpat, loop_start); | |
1640 | ||
1641 | /* Mark the moved, invariant reg as being allowed to | |
1642 | share a hard reg with the other matching invariant. */ | |
1643 | REG_NOTES (i1) = REG_NOTES (m->insn); | |
1644 | r1 = SET_DEST (PATTERN (m->insn)); | |
1645 | r2 = SET_DEST (PATTERN (m1->insn)); | |
1646 | regs_may_share = gen_rtx (EXPR_LIST, VOIDmode, r1, | |
1647 | gen_rtx (EXPR_LIST, VOIDmode, r2, | |
1648 | regs_may_share)); | |
1649 | delete_insn (m->insn); | |
1650 | ||
1651 | if (new_start == 0) | |
1652 | new_start = i1; | |
1653 | ||
1654 | if (loop_dump_stream) | |
1655 | fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1)); | |
1656 | } | |
1657 | /* If we are to re-generate the item being moved with a | |
1658 | new move insn, first delete what we have and then emit | |
1659 | the move insn before the loop. */ | |
1660 | else if (m->move_insn) | |
1661 | { | |
1662 | rtx i1, temp; | |
1663 | ||
1664 | for (count = m->consec; count >= 0; count--) | |
1665 | { | |
1666 | /* If this is the first insn of a library call sequence, | |
1667 | skip to the end. */ | |
1668 | if (GET_CODE (p) != NOTE | |
1669 | && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
1670 | p = XEXP (temp, 0); | |
1671 | ||
1672 | /* If this is the last insn of a libcall sequence, then | |
1673 | delete every insn in the sequence except the last. | |
1674 | The last insn is handled in the normal manner. */ | |
1675 | if (GET_CODE (p) != NOTE | |
1676 | && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX))) | |
1677 | { | |
1678 | temp = XEXP (temp, 0); | |
1679 | while (temp != p) | |
1680 | temp = delete_insn (temp); | |
1681 | } | |
1682 | ||
1683 | p = delete_insn (p); | |
1684 | } | |
1685 | ||
1686 | start_sequence (); | |
1687 | emit_move_insn (m->set_dest, m->set_src); | |
1688 | temp = get_insns (); | |
1689 | end_sequence (); | |
1690 | ||
1691 | add_label_notes (m->set_src, temp); | |
1692 | ||
1693 | i1 = emit_insns_before (temp, loop_start); | |
1694 | if (! find_reg_note (i1, REG_EQUAL, NULL_RTX)) | |
1695 | REG_NOTES (i1) | |
1696 | = gen_rtx (EXPR_LIST, | |
1697 | m->is_equiv ? REG_EQUIV : REG_EQUAL, | |
1698 | m->set_src, REG_NOTES (i1)); | |
1699 | ||
1700 | if (loop_dump_stream) | |
1701 | fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1)); | |
1702 | ||
1703 | /* The more regs we move, the less we like moving them. */ | |
1704 | threshold -= 3; | |
1705 | } | |
1706 | else | |
1707 | { | |
1708 | for (count = m->consec; count >= 0; count--) | |
1709 | { | |
1710 | rtx i1, temp; | |
1711 | ||
1712 | /* If first insn of libcall sequence, skip to end. */ | |
1713 | /* Do this at start of loop, since p is guaranteed to | |
1714 | be an insn here. */ | |
1715 | if (GET_CODE (p) != NOTE | |
1716 | && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
1717 | p = XEXP (temp, 0); | |
1718 | ||
1719 | /* If last insn of libcall sequence, move all | |
1720 | insns except the last before the loop. The last | |
1721 | insn is handled in the normal manner. */ | |
1722 | if (GET_CODE (p) != NOTE | |
1723 | && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX))) | |
1724 | { | |
1725 | rtx fn_address = 0; | |
1726 | rtx fn_reg = 0; | |
1727 | rtx fn_address_insn = 0; | |
1728 | ||
1729 | first = 0; | |
1730 | for (temp = XEXP (temp, 0); temp != p; | |
1731 | temp = NEXT_INSN (temp)) | |
1732 | { | |
1733 | rtx body; | |
1734 | rtx n; | |
1735 | rtx next; | |
1736 | ||
1737 | if (GET_CODE (temp) == NOTE) | |
1738 | continue; | |
1739 | ||
1740 | body = PATTERN (temp); | |
1741 | ||
1742 | /* Find the next insn after TEMP, | |
1743 | not counting USE or NOTE insns. */ | |
1744 | for (next = NEXT_INSN (temp); next != p; | |
1745 | next = NEXT_INSN (next)) | |
1746 | if (! (GET_CODE (next) == INSN | |
1747 | && GET_CODE (PATTERN (next)) == USE) | |
1748 | && GET_CODE (next) != NOTE) | |
1749 | break; | |
1750 | ||
1751 | /* If that is the call, this may be the insn | |
1752 | that loads the function address. | |
1753 | ||
1754 | Extract the function address from the insn | |
1755 | that loads it into a register. | |
1756 | If this insn was cse'd, we get incorrect code. | |
1757 | ||
1758 | So emit a new move insn that copies the | |
1759 | function address into the register that the | |
1760 | call insn will use. flow.c will delete any | |
1761 | redundant stores that we have created. */ | |
1762 | if (GET_CODE (next) == CALL_INSN | |
1763 | && GET_CODE (body) == SET | |
1764 | && GET_CODE (SET_DEST (body)) == REG | |
1765 | && (n = find_reg_note (temp, REG_EQUAL, | |
1766 | NULL_RTX))) | |
1767 | { | |
1768 | fn_reg = SET_SRC (body); | |
1769 | if (GET_CODE (fn_reg) != REG) | |
1770 | fn_reg = SET_DEST (body); | |
1771 | fn_address = XEXP (n, 0); | |
1772 | fn_address_insn = temp; | |
1773 | } | |
1774 | /* We have the call insn. | |
1775 | If it uses the register we suspect it might, | |
1776 | load it with the correct address directly. */ | |
1777 | if (GET_CODE (temp) == CALL_INSN | |
1778 | && fn_address != 0 | |
1779 | && reg_referenced_p (fn_reg, body)) | |
1780 | emit_insn_after (gen_move_insn (fn_reg, | |
1781 | fn_address), | |
1782 | fn_address_insn); | |
1783 | ||
1784 | if (GET_CODE (temp) == CALL_INSN) | |
1785 | i1 = emit_call_insn_before (body, loop_start); | |
1786 | else | |
1787 | i1 = emit_insn_before (body, loop_start); | |
1788 | if (first == 0) | |
1789 | first = i1; | |
1790 | if (temp == fn_address_insn) | |
1791 | fn_address_insn = i1; | |
1792 | REG_NOTES (i1) = REG_NOTES (temp); | |
1793 | delete_insn (temp); | |
1794 | } | |
1795 | } | |
1796 | if (m->savemode != VOIDmode) | |
1797 | { | |
1798 | /* P sets REG to zero; but we should clear only | |
1799 | the bits that are not covered by the mode | |
1800 | m->savemode. */ | |
1801 | rtx reg = m->set_dest; | |
1802 | rtx sequence; | |
1803 | rtx tem; | |
1804 | ||
1805 | start_sequence (); | |
1806 | tem = expand_binop | |
1807 | (GET_MODE (reg), and_optab, reg, | |
1808 | GEN_INT ((((HOST_WIDE_INT) 1 | |
1809 | << GET_MODE_BITSIZE (m->savemode))) | |
1810 | - 1), | |
1811 | reg, 1, OPTAB_LIB_WIDEN); | |
1812 | if (tem == 0) | |
1813 | abort (); | |
1814 | if (tem != reg) | |
1815 | emit_move_insn (reg, tem); | |
1816 | sequence = gen_sequence (); | |
1817 | end_sequence (); | |
1818 | i1 = emit_insn_before (sequence, loop_start); | |
1819 | } | |
1820 | else if (GET_CODE (p) == CALL_INSN) | |
1821 | i1 = emit_call_insn_before (PATTERN (p), loop_start); | |
1822 | else | |
1823 | i1 = emit_insn_before (PATTERN (p), loop_start); | |
1824 | ||
1825 | REG_NOTES (i1) = REG_NOTES (p); | |
1826 | ||
2a5f595d PR |
1827 | /* If there is a REG_EQUAL note present whose value is |
1828 | not loop invariant, then delete it, since it may | |
1829 | cause problems with later optimization passes. | |
1830 | It is possible for cse to create such notes | |
1831 | like this as a result of record_jump_cond. */ | |
1832 | ||
1833 | if ((temp = find_reg_note (i1, REG_EQUAL, NULL_RTX)) | |
1834 | && ! invariant_p (XEXP (temp, 0))) | |
1835 | remove_note (i1, temp); | |
1836 | ||
9bf86ebb PR |
1837 | if (new_start == 0) |
1838 | new_start = i1; | |
1839 | ||
1840 | if (loop_dump_stream) | |
1841 | fprintf (loop_dump_stream, " moved to %d", | |
1842 | INSN_UID (i1)); | |
1843 | ||
1844 | #if 0 | |
1845 | /* This isn't needed because REG_NOTES is copied | |
1846 | below and is wrong since P might be a PARALLEL. */ | |
1847 | if (REG_NOTES (i1) == 0 | |
1848 | && ! m->partial /* But not if it's a zero-extend clr. */ | |
1849 | && ! m->global /* and not if used outside the loop | |
1850 | (since it might get set outside). */ | |
1851 | && CONSTANT_P (SET_SRC (PATTERN (p)))) | |
1852 | REG_NOTES (i1) | |
1853 | = gen_rtx (EXPR_LIST, REG_EQUAL, | |
1854 | SET_SRC (PATTERN (p)), REG_NOTES (i1)); | |
1855 | #endif | |
1856 | ||
1857 | /* If library call, now fix the REG_NOTES that contain | |
1858 | insn pointers, namely REG_LIBCALL on FIRST | |
1859 | and REG_RETVAL on I1. */ | |
1860 | if (temp = find_reg_note (i1, REG_RETVAL, NULL_RTX)) | |
1861 | { | |
1862 | XEXP (temp, 0) = first; | |
1863 | temp = find_reg_note (first, REG_LIBCALL, NULL_RTX); | |
1864 | XEXP (temp, 0) = i1; | |
1865 | } | |
1866 | ||
1867 | delete_insn (p); | |
1868 | do p = NEXT_INSN (p); | |
1869 | while (p && GET_CODE (p) == NOTE); | |
1870 | } | |
1871 | ||
1872 | /* The more regs we move, the less we like moving them. */ | |
1873 | threshold -= 3; | |
1874 | } | |
1875 | ||
1876 | /* Any other movable that loads the same register | |
1877 | MUST be moved. */ | |
1878 | already_moved[regno] = 1; | |
1879 | ||
1880 | /* This reg has been moved out of one loop. */ | |
1881 | moved_once[regno] = 1; | |
1882 | ||
1883 | /* The reg set here is now invariant. */ | |
1884 | if (! m->partial) | |
1885 | n_times_set[regno] = 0; | |
1886 | ||
1887 | m->done = 1; | |
1888 | ||
1889 | /* Change the length-of-life info for the register | |
1890 | to say it lives at least the full length of this loop. | |
1891 | This will help guide optimizations in outer loops. */ | |
1892 | ||
1893 | if (uid_luid[regno_first_uid[regno]] > INSN_LUID (loop_start)) | |
1894 | /* This is the old insn before all the moved insns. | |
1895 | We can't use the moved insn because it is out of range | |
1896 | in uid_luid. Only the old insns have luids. */ | |
1897 | regno_first_uid[regno] = INSN_UID (loop_start); | |
1898 | if (uid_luid[regno_last_uid[regno]] < INSN_LUID (end)) | |
1899 | regno_last_uid[regno] = INSN_UID (end); | |
1900 | ||
1901 | /* Combine with this moved insn any other matching movables. */ | |
1902 | ||
1903 | if (! m->partial) | |
1904 | for (m1 = movables; m1; m1 = m1->next) | |
1905 | if (m1->match == m) | |
1906 | { | |
1907 | rtx temp; | |
1908 | ||
1909 | /* Schedule the reg loaded by M1 | |
1910 | for replacement so that shares the reg of M. | |
1911 | If the modes differ (only possible in restricted | |
1912 | circumstances, make a SUBREG. */ | |
1913 | if (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest)) | |
1914 | reg_map[m1->regno] = m->set_dest; | |
1915 | else | |
1916 | reg_map[m1->regno] | |
1917 | = gen_lowpart_common (GET_MODE (m1->set_dest), | |
1918 | m->set_dest); | |
1919 | ||
1920 | /* Get rid of the matching insn | |
1921 | and prevent further processing of it. */ | |
1922 | m1->done = 1; | |
1923 | ||
1924 | /* if library call, delete all insn except last, which | |
1925 | is deleted below */ | |
1926 | if (temp = find_reg_note (m1->insn, REG_RETVAL, | |
1927 | NULL_RTX)) | |
1928 | { | |
1929 | for (temp = XEXP (temp, 0); temp != m1->insn; | |
1930 | temp = NEXT_INSN (temp)) | |
1931 | delete_insn (temp); | |
1932 | } | |
1933 | delete_insn (m1->insn); | |
1934 | ||
1935 | /* Any other movable that loads the same register | |
1936 | MUST be moved. */ | |
1937 | already_moved[m1->regno] = 1; | |
1938 | ||
1939 | /* The reg merged here is now invariant, | |
1940 | if the reg it matches is invariant. */ | |
1941 | if (! m->partial) | |
1942 | n_times_set[m1->regno] = 0; | |
1943 | } | |
1944 | } | |
1945 | else if (loop_dump_stream) | |
1946 | fprintf (loop_dump_stream, "not desirable"); | |
1947 | } | |
1948 | else if (loop_dump_stream && !m->match) | |
1949 | fprintf (loop_dump_stream, "not safe"); | |
1950 | ||
1951 | if (loop_dump_stream) | |
1952 | fprintf (loop_dump_stream, "\n"); | |
1953 | } | |
1954 | ||
1955 | if (new_start == 0) | |
1956 | new_start = loop_start; | |
1957 | ||
1958 | /* Go through all the instructions in the loop, making | |
1959 | all the register substitutions scheduled in REG_MAP. */ | |
1960 | for (p = new_start; p != end; p = NEXT_INSN (p)) | |
1961 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
1962 | || GET_CODE (p) == CALL_INSN) | |
1963 | { | |
1964 | replace_regs (PATTERN (p), reg_map, nregs, 0); | |
1965 | replace_regs (REG_NOTES (p), reg_map, nregs, 0); | |
1966 | INSN_CODE (p) = -1; | |
1967 | } | |
1968 | } | |
1969 | \f | |
1970 | #if 0 | |
1971 | /* Scan X and replace the address of any MEM in it with ADDR. | |
1972 | REG is the address that MEM should have before the replacement. */ | |
1973 | ||
1974 | static void | |
1975 | replace_call_address (x, reg, addr) | |
1976 | rtx x, reg, addr; | |
1977 | { | |
1978 | register enum rtx_code code; | |
1979 | register int i; | |
1980 | register char *fmt; | |
1981 | ||
1982 | if (x == 0) | |
1983 | return; | |
1984 | code = GET_CODE (x); | |
1985 | switch (code) | |
1986 | { | |
1987 | case PC: | |
1988 | case CC0: | |
1989 | case CONST_INT: | |
1990 | case CONST_DOUBLE: | |
1991 | case CONST: | |
1992 | case SYMBOL_REF: | |
1993 | case LABEL_REF: | |
1994 | case REG: | |
1995 | return; | |
1996 | ||
1997 | case SET: | |
1998 | /* Short cut for very common case. */ | |
1999 | replace_call_address (XEXP (x, 1), reg, addr); | |
2000 | return; | |
2001 | ||
2002 | case CALL: | |
2003 | /* Short cut for very common case. */ | |
2004 | replace_call_address (XEXP (x, 0), reg, addr); | |
2005 | return; | |
2006 | ||
2007 | case MEM: | |
2008 | /* If this MEM uses a reg other than the one we expected, | |
2009 | something is wrong. */ | |
2010 | if (XEXP (x, 0) != reg) | |
2011 | abort (); | |
2012 | XEXP (x, 0) = addr; | |
2013 | return; | |
2014 | } | |
2015 | ||
2016 | fmt = GET_RTX_FORMAT (code); | |
2017 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2018 | { | |
2019 | if (fmt[i] == 'e') | |
2020 | replace_call_address (XEXP (x, i), reg, addr); | |
2021 | if (fmt[i] == 'E') | |
2022 | { | |
2023 | register int j; | |
2024 | for (j = 0; j < XVECLEN (x, i); j++) | |
2025 | replace_call_address (XVECEXP (x, i, j), reg, addr); | |
2026 | } | |
2027 | } | |
2028 | } | |
2029 | #endif | |
2030 | \f | |
2031 | /* Return the number of memory refs to addresses that vary | |
2032 | in the rtx X. */ | |
2033 | ||
2034 | static int | |
2035 | count_nonfixed_reads (x) | |
2036 | rtx x; | |
2037 | { | |
2038 | register enum rtx_code code; | |
2039 | register int i; | |
2040 | register char *fmt; | |
2041 | int value; | |
2042 | ||
2043 | if (x == 0) | |
2044 | return 0; | |
2045 | ||
2046 | code = GET_CODE (x); | |
2047 | switch (code) | |
2048 | { | |
2049 | case PC: | |
2050 | case CC0: | |
2051 | case CONST_INT: | |
2052 | case CONST_DOUBLE: | |
2053 | case CONST: | |
2054 | case SYMBOL_REF: | |
2055 | case LABEL_REF: | |
2056 | case REG: | |
2057 | return 0; | |
2058 | ||
2059 | case MEM: | |
2060 | return ((invariant_p (XEXP (x, 0)) != 1) | |
2061 | + count_nonfixed_reads (XEXP (x, 0))); | |
2062 | } | |
2063 | ||
2064 | value = 0; | |
2065 | fmt = GET_RTX_FORMAT (code); | |
2066 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2067 | { | |
2068 | if (fmt[i] == 'e') | |
2069 | value += count_nonfixed_reads (XEXP (x, i)); | |
2070 | if (fmt[i] == 'E') | |
2071 | { | |
2072 | register int j; | |
2073 | for (j = 0; j < XVECLEN (x, i); j++) | |
2074 | value += count_nonfixed_reads (XVECEXP (x, i, j)); | |
2075 | } | |
2076 | } | |
2077 | return value; | |
2078 | } | |
2079 | ||
2080 | \f | |
2081 | #if 0 | |
2082 | /* P is an instruction that sets a register to the result of a ZERO_EXTEND. | |
2083 | Replace it with an instruction to load just the low bytes | |
2084 | if the machine supports such an instruction, | |
2085 | and insert above LOOP_START an instruction to clear the register. */ | |
2086 | ||
2087 | static void | |
2088 | constant_high_bytes (p, loop_start) | |
2089 | rtx p, loop_start; | |
2090 | { | |
2091 | register rtx new; | |
2092 | register int insn_code_number; | |
2093 | ||
2094 | /* Try to change (SET (REG ...) (ZERO_EXTEND (..:B ...))) | |
2095 | to (SET (STRICT_LOW_PART (SUBREG:B (REG...))) ...). */ | |
2096 | ||
2097 | new = gen_rtx (SET, VOIDmode, | |
2098 | gen_rtx (STRICT_LOW_PART, VOIDmode, | |
2099 | gen_rtx (SUBREG, GET_MODE (XEXP (SET_SRC (PATTERN (p)), 0)), | |
2100 | SET_DEST (PATTERN (p)), | |
2101 | 0)), | |
2102 | XEXP (SET_SRC (PATTERN (p)), 0)); | |
2103 | insn_code_number = recog (new, p); | |
2104 | ||
2105 | if (insn_code_number) | |
2106 | { | |
2107 | register int i; | |
2108 | ||
2109 | /* Clear destination register before the loop. */ | |
2110 | emit_insn_before (gen_rtx (SET, VOIDmode, | |
2111 | SET_DEST (PATTERN (p)), | |
2112 | const0_rtx), | |
2113 | loop_start); | |
2114 | ||
2115 | /* Inside the loop, just load the low part. */ | |
2116 | PATTERN (p) = new; | |
2117 | } | |
2118 | } | |
2119 | #endif | |
2120 | \f | |
2121 | /* Scan a loop setting the variables `unknown_address_altered', | |
2122 | `num_mem_sets', `loop_continue', loops_enclosed', `loop_has_call', | |
2123 | and `loop_has_volatile'. | |
2124 | Also, fill in the array `loop_store_mems'. */ | |
2125 | ||
2126 | static void | |
2127 | prescan_loop (start, end) | |
2128 | rtx start, end; | |
2129 | { | |
2130 | register int level = 1; | |
2131 | register rtx insn; | |
2132 | ||
2133 | unknown_address_altered = 0; | |
2134 | loop_has_call = 0; | |
2135 | loop_has_volatile = 0; | |
2136 | loop_store_mems_idx = 0; | |
2137 | ||
2138 | num_mem_sets = 0; | |
2139 | loops_enclosed = 1; | |
2140 | loop_continue = 0; | |
2141 | ||
2142 | for (insn = NEXT_INSN (start); insn != NEXT_INSN (end); | |
2143 | insn = NEXT_INSN (insn)) | |
2144 | { | |
2145 | if (GET_CODE (insn) == NOTE) | |
2146 | { | |
2147 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
2148 | { | |
2149 | ++level; | |
2150 | /* Count number of loops contained in this one. */ | |
2151 | loops_enclosed++; | |
2152 | } | |
2153 | else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) | |
2154 | { | |
2155 | --level; | |
2156 | if (level == 0) | |
2157 | { | |
2158 | end = insn; | |
2159 | break; | |
2160 | } | |
2161 | } | |
2162 | else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT) | |
2163 | { | |
2164 | if (level == 1) | |
2165 | loop_continue = insn; | |
2166 | } | |
2167 | } | |
2168 | else if (GET_CODE (insn) == CALL_INSN) | |
2169 | { | |
2170 | unknown_address_altered = 1; | |
2171 | loop_has_call = 1; | |
2172 | } | |
2173 | else | |
2174 | { | |
2175 | if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN) | |
2176 | { | |
2177 | if (volatile_refs_p (PATTERN (insn))) | |
2178 | loop_has_volatile = 1; | |
2179 | ||
2180 | note_stores (PATTERN (insn), note_addr_stored); | |
2181 | } | |
2182 | } | |
2183 | } | |
2184 | } | |
2185 | \f | |
2186 | /* Scan the function looking for loops. Record the start and end of each loop. | |
2187 | Also mark as invalid loops any loops that contain a setjmp or are branched | |
2188 | to from outside the loop. */ | |
2189 | ||
2190 | static void | |
2191 | find_and_verify_loops (f) | |
2192 | rtx f; | |
2193 | { | |
2194 | rtx insn, label; | |
2195 | int current_loop = -1; | |
2196 | int next_loop = -1; | |
2197 | int loop; | |
2198 | ||
2199 | /* If there are jumps to undefined labels, | |
2200 | treat them as jumps out of any/all loops. | |
2201 | This also avoids writing past end of tables when there are no loops. */ | |
2202 | uid_loop_num[0] = -1; | |
2203 | ||
2204 | /* Find boundaries of loops, mark which loops are contained within | |
2205 | loops, and invalidate loops that have setjmp. */ | |
2206 | ||
2207 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
2208 | { | |
2209 | if (GET_CODE (insn) == NOTE) | |
2210 | switch (NOTE_LINE_NUMBER (insn)) | |
2211 | { | |
2212 | case NOTE_INSN_LOOP_BEG: | |
2213 | loop_number_loop_starts[++next_loop] = insn; | |
2214 | loop_number_loop_ends[next_loop] = 0; | |
2215 | loop_outer_loop[next_loop] = current_loop; | |
2216 | loop_invalid[next_loop] = 0; | |
2217 | loop_number_exit_labels[next_loop] = 0; | |
2218 | current_loop = next_loop; | |
2219 | break; | |
2220 | ||
2221 | case NOTE_INSN_SETJMP: | |
2222 | /* In this case, we must invalidate our current loop and any | |
2223 | enclosing loop. */ | |
2224 | for (loop = current_loop; loop != -1; loop = loop_outer_loop[loop]) | |
2225 | { | |
2226 | loop_invalid[loop] = 1; | |
2227 | if (loop_dump_stream) | |
2228 | fprintf (loop_dump_stream, | |
2229 | "\nLoop at %d ignored due to setjmp.\n", | |
2230 | INSN_UID (loop_number_loop_starts[loop])); | |
2231 | } | |
2232 | break; | |
2233 | ||
2234 | case NOTE_INSN_LOOP_END: | |
2235 | if (current_loop == -1) | |
2236 | abort (); | |
2237 | ||
2238 | loop_number_loop_ends[current_loop] = insn; | |
2239 | current_loop = loop_outer_loop[current_loop]; | |
2240 | break; | |
2241 | ||
2242 | } | |
2243 | ||
2244 | /* Note that this will mark the NOTE_INSN_LOOP_END note as being in the | |
2245 | enclosing loop, but this doesn't matter. */ | |
2246 | uid_loop_num[INSN_UID (insn)] = current_loop; | |
2247 | } | |
2248 | ||
2249 | /* Any loop containing a label used in an initializer must be invalidated, | |
2250 | because it can be jumped into from anywhere. */ | |
2251 | ||
2252 | for (label = forced_labels; label; label = XEXP (label, 1)) | |
2253 | { | |
2254 | int loop_num; | |
2255 | ||
2256 | for (loop_num = uid_loop_num[INSN_UID (XEXP (label, 0))]; | |
2257 | loop_num != -1; | |
2258 | loop_num = loop_outer_loop[loop_num]) | |
2259 | loop_invalid[loop_num] = 1; | |
2260 | } | |
2261 | ||
2262 | /* Now scan all insn's in the function. If any JUMP_INSN branches into a | |
2263 | loop that it is not contained within, that loop is marked invalid. | |
2264 | If any INSN or CALL_INSN uses a label's address, then the loop containing | |
2265 | that label is marked invalid, because it could be jumped into from | |
2266 | anywhere. | |
2267 | ||
2268 | Also look for blocks of code ending in an unconditional branch that | |
2269 | exits the loop. If such a block is surrounded by a conditional | |
2270 | branch around the block, move the block elsewhere (see below) and | |
2271 | invert the jump to point to the code block. This may eliminate a | |
2272 | label in our loop and will simplify processing by both us and a | |
2273 | possible second cse pass. */ | |
2274 | ||
2275 | for (insn = f; insn; insn = NEXT_INSN (insn)) | |
2276 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
2277 | { | |
2278 | int this_loop_num = uid_loop_num[INSN_UID (insn)]; | |
2279 | ||
2280 | if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN) | |
2281 | { | |
2282 | rtx note = find_reg_note (insn, REG_LABEL, NULL_RTX); | |
2283 | if (note) | |
2284 | { | |
2285 | int loop_num; | |
2286 | ||
2287 | for (loop_num = uid_loop_num[INSN_UID (XEXP (note, 0))]; | |
2288 | loop_num != -1; | |
2289 | loop_num = loop_outer_loop[loop_num]) | |
2290 | loop_invalid[loop_num] = 1; | |
2291 | } | |
2292 | } | |
2293 | ||
2294 | if (GET_CODE (insn) != JUMP_INSN) | |
2295 | continue; | |
2296 | ||
2297 | mark_loop_jump (PATTERN (insn), this_loop_num); | |
2298 | ||
2299 | /* See if this is an unconditional branch outside the loop. */ | |
2300 | if (this_loop_num != -1 | |
2301 | && (GET_CODE (PATTERN (insn)) == RETURN | |
2302 | || (simplejump_p (insn) | |
2303 | && (uid_loop_num[INSN_UID (JUMP_LABEL (insn))] | |
2304 | != this_loop_num))) | |
2305 | && get_max_uid () < max_uid_for_loop) | |
2306 | { | |
2307 | rtx p; | |
2308 | rtx our_next = next_real_insn (insn); | |
2309 | ||
2310 | /* Go backwards until we reach the start of the loop, a label, | |
2311 | or a JUMP_INSN. */ | |
2312 | for (p = PREV_INSN (insn); | |
2313 | GET_CODE (p) != CODE_LABEL | |
2314 | && ! (GET_CODE (p) == NOTE | |
2315 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG) | |
2316 | && GET_CODE (p) != JUMP_INSN; | |
2317 | p = PREV_INSN (p)) | |
2318 | ; | |
2319 | ||
2320 | /* If we stopped on a JUMP_INSN to the next insn after INSN, | |
2321 | we have a block of code to try to move. | |
2322 | ||
2323 | We look backward and then forward from the target of INSN | |
2324 | to find a BARRIER at the same loop depth as the target. | |
2325 | If we find such a BARRIER, we make a new label for the start | |
2326 | of the block, invert the jump in P and point it to that label, | |
2327 | and move the block of code to the spot we found. */ | |
2328 | ||
2329 | if (GET_CODE (p) == JUMP_INSN | |
2330 | && JUMP_LABEL (p) != 0 | |
2331 | /* Just ignore jumps to labels that were never emitted. | |
2332 | These always indicate compilation errors. */ | |
2333 | && INSN_UID (JUMP_LABEL (p)) != 0 | |
2334 | && condjump_p (p) | |
2335 | && ! simplejump_p (p) | |
2336 | && next_real_insn (JUMP_LABEL (p)) == our_next) | |
2337 | { | |
2338 | rtx target | |
2339 | = JUMP_LABEL (insn) ? JUMP_LABEL (insn) : get_last_insn (); | |
2340 | int target_loop_num = uid_loop_num[INSN_UID (target)]; | |
2341 | rtx loc; | |
2342 | ||
2343 | for (loc = target; loc; loc = PREV_INSN (loc)) | |
2344 | if (GET_CODE (loc) == BARRIER | |
2345 | && uid_loop_num[INSN_UID (loc)] == target_loop_num) | |
2346 | break; | |
2347 | ||
2348 | if (loc == 0) | |
2349 | for (loc = target; loc; loc = NEXT_INSN (loc)) | |
2350 | if (GET_CODE (loc) == BARRIER | |
2351 | && uid_loop_num[INSN_UID (loc)] == target_loop_num) | |
2352 | break; | |
2353 | ||
2354 | if (loc) | |
2355 | { | |
2356 | rtx cond_label = JUMP_LABEL (p); | |
2357 | rtx new_label = get_label_after (p); | |
2358 | ||
2359 | /* Ensure our label doesn't go away. */ | |
2360 | LABEL_NUSES (cond_label)++; | |
2361 | ||
2362 | /* Verify that uid_loop_num is large enough and that | |
2363 | we can invert P. */ | |
2364 | if (invert_jump (p, new_label)) | |
2365 | { | |
2366 | rtx q, r; | |
2367 | ||
2368 | /* Include the BARRIER after INSN and copy the | |
2369 | block after LOC. */ | |
2370 | new_label = squeeze_notes (new_label, NEXT_INSN (insn)); | |
2371 | reorder_insns (new_label, NEXT_INSN (insn), loc); | |
2372 | ||
2373 | /* All those insns are now in TARGET_LOOP_NUM. */ | |
2374 | for (q = new_label; q != NEXT_INSN (NEXT_INSN (insn)); | |
2375 | q = NEXT_INSN (q)) | |
2376 | uid_loop_num[INSN_UID (q)] = target_loop_num; | |
2377 | ||
2378 | /* The label jumped to by INSN is no longer a loop exit. | |
2379 | Unless INSN does not have a label (e.g., it is a | |
2380 | RETURN insn), search loop_number_exit_labels to find | |
2381 | its label_ref, and remove it. Also turn off | |
2382 | LABEL_OUTSIDE_LOOP_P bit. */ | |
2383 | if (JUMP_LABEL (insn)) | |
2384 | { | |
2385 | for (q = 0, | |
2386 | r = loop_number_exit_labels[this_loop_num]; | |
2387 | r; q = r, r = LABEL_NEXTREF (r)) | |
2388 | if (XEXP (r, 0) == JUMP_LABEL (insn)) | |
2389 | { | |
2390 | LABEL_OUTSIDE_LOOP_P (r) = 0; | |
2391 | if (q) | |
2392 | LABEL_NEXTREF (q) = LABEL_NEXTREF (r); | |
2393 | else | |
2394 | loop_number_exit_labels[this_loop_num] | |
2395 | = LABEL_NEXTREF (r); | |
2396 | break; | |
2397 | } | |
2398 | ||
2399 | /* If we didn't find it, then something is wrong. */ | |
2400 | if (! r) | |
2401 | abort (); | |
2402 | } | |
2403 | ||
2404 | /* P is now a jump outside the loop, so it must be put | |
2405 | in loop_number_exit_labels, and marked as such. | |
2406 | The easiest way to do this is to just call | |
2407 | mark_loop_jump again for P. */ | |
2408 | mark_loop_jump (PATTERN (p), this_loop_num); | |
2409 | ||
2410 | /* If INSN now jumps to the insn after it, | |
2411 | delete INSN. */ | |
2412 | if (JUMP_LABEL (insn) != 0 | |
2413 | && (next_real_insn (JUMP_LABEL (insn)) | |
2414 | == next_real_insn (insn))) | |
2415 | delete_insn (insn); | |
2416 | } | |
2417 | ||
2418 | /* Continue the loop after where the conditional | |
2419 | branch used to jump, since the only branch insn | |
2420 | in the block (if it still remains) is an inter-loop | |
2421 | branch and hence needs no processing. */ | |
2422 | insn = NEXT_INSN (cond_label); | |
2423 | ||
2424 | if (--LABEL_NUSES (cond_label) == 0) | |
2425 | delete_insn (cond_label); | |
2426 | } | |
2427 | } | |
2428 | } | |
2429 | } | |
2430 | } | |
2431 | ||
2432 | /* If any label in X jumps to a loop different from LOOP_NUM and any of the | |
2433 | loops it is contained in, mark the target loop invalid. | |
2434 | ||
2435 | For speed, we assume that X is part of a pattern of a JUMP_INSN. */ | |
2436 | ||
2437 | static void | |
2438 | mark_loop_jump (x, loop_num) | |
2439 | rtx x; | |
2440 | int loop_num; | |
2441 | { | |
2442 | int dest_loop; | |
2443 | int outer_loop; | |
2444 | int i; | |
2445 | ||
2446 | switch (GET_CODE (x)) | |
2447 | { | |
2448 | case PC: | |
2449 | case USE: | |
2450 | case CLOBBER: | |
2451 | case REG: | |
2452 | case MEM: | |
2453 | case CONST_INT: | |
2454 | case CONST_DOUBLE: | |
2455 | case RETURN: | |
2456 | return; | |
2457 | ||
2458 | case CONST: | |
2459 | /* There could be a label reference in here. */ | |
2460 | mark_loop_jump (XEXP (x, 0), loop_num); | |
2461 | return; | |
2462 | ||
2463 | case PLUS: | |
2464 | case MINUS: | |
2465 | case MULT: | |
2466 | case LSHIFT: | |
2467 | mark_loop_jump (XEXP (x, 0), loop_num); | |
2468 | mark_loop_jump (XEXP (x, 1), loop_num); | |
2469 | return; | |
2470 | ||
2471 | case SIGN_EXTEND: | |
2472 | case ZERO_EXTEND: | |
2473 | mark_loop_jump (XEXP (x, 0), loop_num); | |
2474 | return; | |
2475 | ||
2476 | case LABEL_REF: | |
2477 | dest_loop = uid_loop_num[INSN_UID (XEXP (x, 0))]; | |
2478 | ||
2479 | /* Link together all labels that branch outside the loop. This | |
2480 | is used by final_[bg]iv_value and the loop unrolling code. Also | |
2481 | mark this LABEL_REF so we know that this branch should predict | |
2482 | false. */ | |
2483 | ||
2484 | if (dest_loop != loop_num && loop_num != -1) | |
2485 | { | |
2486 | LABEL_OUTSIDE_LOOP_P (x) = 1; | |
2487 | LABEL_NEXTREF (x) = loop_number_exit_labels[loop_num]; | |
2488 | loop_number_exit_labels[loop_num] = x; | |
2489 | } | |
2490 | ||
2491 | /* If this is inside a loop, but not in the current loop or one enclosed | |
2492 | by it, it invalidates at least one loop. */ | |
2493 | ||
2494 | if (dest_loop == -1) | |
2495 | return; | |
2496 | ||
2497 | /* We must invalidate every nested loop containing the target of this | |
2498 | label, except those that also contain the jump insn. */ | |
2499 | ||
2500 | for (; dest_loop != -1; dest_loop = loop_outer_loop[dest_loop]) | |
2501 | { | |
2502 | /* Stop when we reach a loop that also contains the jump insn. */ | |
2503 | for (outer_loop = loop_num; outer_loop != -1; | |
2504 | outer_loop = loop_outer_loop[outer_loop]) | |
2505 | if (dest_loop == outer_loop) | |
2506 | return; | |
2507 | ||
2508 | /* If we get here, we know we need to invalidate a loop. */ | |
2509 | if (loop_dump_stream && ! loop_invalid[dest_loop]) | |
2510 | fprintf (loop_dump_stream, | |
2511 | "\nLoop at %d ignored due to multiple entry points.\n", | |
2512 | INSN_UID (loop_number_loop_starts[dest_loop])); | |
2513 | ||
2514 | loop_invalid[dest_loop] = 1; | |
2515 | } | |
2516 | return; | |
2517 | ||
2518 | case SET: | |
2519 | /* If this is not setting pc, ignore. */ | |
2520 | if (SET_DEST (x) == pc_rtx) | |
2521 | mark_loop_jump (SET_SRC (x), loop_num); | |
2522 | return; | |
2523 | ||
2524 | case IF_THEN_ELSE: | |
2525 | mark_loop_jump (XEXP (x, 1), loop_num); | |
2526 | mark_loop_jump (XEXP (x, 2), loop_num); | |
2527 | return; | |
2528 | ||
2529 | case PARALLEL: | |
2530 | case ADDR_VEC: | |
2531 | for (i = 0; i < XVECLEN (x, 0); i++) | |
2532 | mark_loop_jump (XVECEXP (x, 0, i), loop_num); | |
2533 | return; | |
2534 | ||
2535 | case ADDR_DIFF_VEC: | |
2536 | for (i = 0; i < XVECLEN (x, 1); i++) | |
2537 | mark_loop_jump (XVECEXP (x, 1, i), loop_num); | |
2538 | return; | |
2539 | ||
2540 | default: | |
2541 | /* Nothing else should occur in a JUMP_INSN. */ | |
2542 | abort (); | |
2543 | } | |
2544 | } | |
2545 | \f | |
2546 | /* Return nonzero if there is a label in the range from | |
2547 | insn INSN to and including the insn whose luid is END | |
2548 | INSN must have an assigned luid (i.e., it must not have | |
2549 | been previously created by loop.c). */ | |
2550 | ||
2551 | static int | |
2552 | labels_in_range_p (insn, end) | |
2553 | rtx insn; | |
2554 | int end; | |
2555 | { | |
2556 | while (insn && INSN_LUID (insn) <= end) | |
2557 | { | |
2558 | if (GET_CODE (insn) == CODE_LABEL) | |
2559 | return 1; | |
2560 | insn = NEXT_INSN (insn); | |
2561 | } | |
2562 | ||
2563 | return 0; | |
2564 | } | |
2565 | ||
2566 | /* Record that a memory reference X is being set. */ | |
2567 | ||
2568 | static void | |
2569 | note_addr_stored (x) | |
2570 | rtx x; | |
2571 | { | |
2572 | register int i; | |
2573 | ||
2574 | if (x == 0 || GET_CODE (x) != MEM) | |
2575 | return; | |
2576 | ||
2577 | /* Count number of memory writes. | |
2578 | This affects heuristics in strength_reduce. */ | |
2579 | num_mem_sets++; | |
2580 | ||
2581 | if (unknown_address_altered) | |
2582 | return; | |
2583 | ||
2584 | for (i = 0; i < loop_store_mems_idx; i++) | |
2585 | if (rtx_equal_p (XEXP (loop_store_mems[i], 0), XEXP (x, 0)) | |
2586 | && MEM_IN_STRUCT_P (x) == MEM_IN_STRUCT_P (loop_store_mems[i])) | |
2587 | { | |
2588 | /* We are storing at the same address as previously noted. Save the | |
2589 | wider reference, treating BLKmode as wider. */ | |
2590 | if (GET_MODE (x) == BLKmode | |
2591 | || (GET_MODE_SIZE (GET_MODE (x)) | |
2592 | > GET_MODE_SIZE (GET_MODE (loop_store_mems[i])))) | |
2593 | loop_store_mems[i] = x; | |
2594 | break; | |
2595 | } | |
2596 | ||
2597 | if (i == NUM_STORES) | |
2598 | unknown_address_altered = 1; | |
2599 | ||
2600 | else if (i == loop_store_mems_idx) | |
2601 | loop_store_mems[loop_store_mems_idx++] = x; | |
2602 | } | |
2603 | \f | |
2604 | /* Return nonzero if the rtx X is invariant over the current loop. | |
2605 | ||
2606 | The value is 2 if we refer to something only conditionally invariant. | |
2607 | ||
2608 | If `unknown_address_altered' is nonzero, no memory ref is invariant. | |
2609 | Otherwise, a memory ref is invariant if it does not conflict with | |
2610 | anything stored in `loop_store_mems'. */ | |
2611 | ||
2612 | int | |
2613 | invariant_p (x) | |
2614 | register rtx x; | |
2615 | { | |
2616 | register int i; | |
2617 | register enum rtx_code code; | |
2618 | register char *fmt; | |
2619 | int conditional = 0; | |
2620 | ||
2621 | if (x == 0) | |
2622 | return 1; | |
2623 | code = GET_CODE (x); | |
2624 | switch (code) | |
2625 | { | |
2626 | case CONST_INT: | |
2627 | case CONST_DOUBLE: | |
2628 | case SYMBOL_REF: | |
2629 | case CONST: | |
2630 | return 1; | |
2631 | ||
2632 | case LABEL_REF: | |
2633 | /* A LABEL_REF is normally invariant, however, if we are unrolling | |
2634 | loops, and this label is inside the loop, then it isn't invariant. | |
2635 | This is because each unrolled copy of the loop body will have | |
2636 | a copy of this label. If this was invariant, then an insn loading | |
2637 | the address of this label into a register might get moved outside | |
2638 | the loop, and then each loop body would end up using the same label. | |
2639 | ||
2640 | We don't know the loop bounds here though, so just fail for all | |
2641 | labels. */ | |
2642 | if (flag_unroll_loops) | |
2643 | return 0; | |
2644 | else | |
2645 | return 1; | |
2646 | ||
2647 | case PC: | |
2648 | case CC0: | |
2649 | case UNSPEC_VOLATILE: | |
2650 | return 0; | |
2651 | ||
2652 | case REG: | |
2653 | /* We used to check RTX_UNCHANGING_P (x) here, but that is invalid | |
2654 | since the reg might be set by initialization within the loop. */ | |
2655 | if (x == frame_pointer_rtx || x == arg_pointer_rtx) | |
2656 | return 1; | |
2657 | if (loop_has_call | |
2658 | && REGNO (x) < FIRST_PSEUDO_REGISTER && call_used_regs[REGNO (x)]) | |
2659 | return 0; | |
2660 | if (n_times_set[REGNO (x)] < 0) | |
2661 | return 2; | |
2662 | return n_times_set[REGNO (x)] == 0; | |
2663 | ||
2664 | case MEM: | |
2665 | /* Read-only items (such as constants in a constant pool) are | |
2666 | invariant if their address is. */ | |
2667 | if (RTX_UNCHANGING_P (x)) | |
2668 | break; | |
2669 | ||
2670 | /* If we filled the table (or had a subroutine call), any location | |
2671 | in memory could have been clobbered. */ | |
2672 | if (unknown_address_altered | |
2673 | /* Don't mess with volatile memory references. */ | |
2674 | || MEM_VOLATILE_P (x)) | |
2675 | return 0; | |
2676 | ||
2677 | /* See if there is any dependence between a store and this load. */ | |
2678 | for (i = loop_store_mems_idx - 1; i >= 0; i--) | |
2679 | if (true_dependence (loop_store_mems[i], x)) | |
2680 | return 0; | |
2681 | ||
2682 | /* It's not invalidated by a store in memory | |
2683 | but we must still verify the address is invariant. */ | |
2684 | break; | |
2685 | ||
2686 | case ASM_OPERANDS: | |
2687 | /* Don't mess with insns declared volatile. */ | |
2688 | if (MEM_VOLATILE_P (x)) | |
2689 | return 0; | |
2690 | } | |
2691 | ||
2692 | fmt = GET_RTX_FORMAT (code); | |
2693 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2694 | { | |
2695 | if (fmt[i] == 'e') | |
2696 | { | |
2697 | int tem = invariant_p (XEXP (x, i)); | |
2698 | if (tem == 0) | |
2699 | return 0; | |
2700 | if (tem == 2) | |
2701 | conditional = 1; | |
2702 | } | |
2703 | else if (fmt[i] == 'E') | |
2704 | { | |
2705 | register int j; | |
2706 | for (j = 0; j < XVECLEN (x, i); j++) | |
2707 | { | |
2708 | int tem = invariant_p (XVECEXP (x, i, j)); | |
2709 | if (tem == 0) | |
2710 | return 0; | |
2711 | if (tem == 2) | |
2712 | conditional = 1; | |
2713 | } | |
2714 | ||
2715 | } | |
2716 | } | |
2717 | ||
2718 | return 1 + conditional; | |
2719 | } | |
2720 | ||
2721 | \f | |
2722 | /* Return nonzero if all the insns in the loop that set REG | |
2723 | are INSN and the immediately following insns, | |
2724 | and if each of those insns sets REG in an invariant way | |
2725 | (not counting uses of REG in them). | |
2726 | ||
2727 | The value is 2 if some of these insns are only conditionally invariant. | |
2728 | ||
2729 | We assume that INSN itself is the first set of REG | |
2730 | and that its source is invariant. */ | |
2731 | ||
2732 | static int | |
2733 | consec_sets_invariant_p (reg, n_sets, insn) | |
2734 | int n_sets; | |
2735 | rtx reg, insn; | |
2736 | { | |
2737 | register rtx p = insn; | |
2738 | register int regno = REGNO (reg); | |
2739 | rtx temp; | |
2740 | /* Number of sets we have to insist on finding after INSN. */ | |
2741 | int count = n_sets - 1; | |
2742 | int old = n_times_set[regno]; | |
2743 | int value = 0; | |
2744 | int this; | |
2745 | ||
2746 | /* If N_SETS hit the limit, we can't rely on its value. */ | |
2747 | if (n_sets == 127) | |
2748 | return 0; | |
2749 | ||
2750 | n_times_set[regno] = 0; | |
2751 | ||
2752 | while (count > 0) | |
2753 | { | |
2754 | register enum rtx_code code; | |
2755 | rtx set; | |
2756 | ||
2757 | p = NEXT_INSN (p); | |
2758 | code = GET_CODE (p); | |
2759 | ||
2760 | /* If library call, skip to end of of it. */ | |
2761 | if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
2762 | p = XEXP (temp, 0); | |
2763 | ||
2764 | this = 0; | |
2765 | if (code == INSN | |
2766 | && (set = single_set (p)) | |
2767 | && GET_CODE (SET_DEST (set)) == REG | |
2768 | && REGNO (SET_DEST (set)) == regno) | |
2769 | { | |
2770 | this = invariant_p (SET_SRC (set)); | |
2771 | if (this != 0) | |
2772 | value |= this; | |
2773 | else if (temp = find_reg_note (p, REG_EQUAL, NULL_RTX)) | |
2774 | { | |
2775 | /* If this is a libcall, then any invariant REG_EQUAL note is OK. | |
2776 | If this is an ordinary insn, then only CONSTANT_P REG_EQUAL | |
2777 | notes are OK. */ | |
2778 | this = (CONSTANT_P (XEXP (temp, 0)) | |
2779 | || (find_reg_note (p, REG_RETVAL, NULL_RTX) | |
2780 | && invariant_p (XEXP (temp, 0)))); | |
2781 | if (this != 0) | |
2782 | value |= this; | |
2783 | } | |
2784 | } | |
2785 | if (this != 0) | |
2786 | count--; | |
2787 | else if (code != NOTE) | |
2788 | { | |
2789 | n_times_set[regno] = old; | |
2790 | return 0; | |
2791 | } | |
2792 | } | |
2793 | ||
2794 | n_times_set[regno] = old; | |
2795 | /* If invariant_p ever returned 2, we return 2. */ | |
2796 | return 1 + (value & 2); | |
2797 | } | |
2798 | ||
2799 | #if 0 | |
2800 | /* I don't think this condition is sufficient to allow INSN | |
2801 | to be moved, so we no longer test it. */ | |
2802 | ||
2803 | /* Return 1 if all insns in the basic block of INSN and following INSN | |
2804 | that set REG are invariant according to TABLE. */ | |
2805 | ||
2806 | static int | |
2807 | all_sets_invariant_p (reg, insn, table) | |
2808 | rtx reg, insn; | |
2809 | short *table; | |
2810 | { | |
2811 | register rtx p = insn; | |
2812 | register int regno = REGNO (reg); | |
2813 | ||
2814 | while (1) | |
2815 | { | |
2816 | register enum rtx_code code; | |
2817 | p = NEXT_INSN (p); | |
2818 | code = GET_CODE (p); | |
2819 | if (code == CODE_LABEL || code == JUMP_INSN) | |
2820 | return 1; | |
2821 | if (code == INSN && GET_CODE (PATTERN (p)) == SET | |
2822 | && GET_CODE (SET_DEST (PATTERN (p))) == REG | |
2823 | && REGNO (SET_DEST (PATTERN (p))) == regno) | |
2824 | { | |
2825 | if (!invariant_p (SET_SRC (PATTERN (p)), table)) | |
2826 | return 0; | |
2827 | } | |
2828 | } | |
2829 | } | |
2830 | #endif /* 0 */ | |
2831 | \f | |
2832 | /* Look at all uses (not sets) of registers in X. For each, if it is | |
2833 | the single use, set USAGE[REGNO] to INSN; if there was a previous use in | |
2834 | a different insn, set USAGE[REGNO] to const0_rtx. */ | |
2835 | ||
2836 | static void | |
2837 | find_single_use_in_loop (insn, x, usage) | |
2838 | rtx insn; | |
2839 | rtx x; | |
2840 | rtx *usage; | |
2841 | { | |
2842 | enum rtx_code code = GET_CODE (x); | |
2843 | char *fmt = GET_RTX_FORMAT (code); | |
2844 | int i, j; | |
2845 | ||
2846 | if (code == REG) | |
2847 | usage[REGNO (x)] | |
2848 | = (usage[REGNO (x)] != 0 && usage[REGNO (x)] != insn) | |
2849 | ? const0_rtx : insn; | |
2850 | ||
2851 | else if (code == SET) | |
2852 | { | |
2853 | /* Don't count SET_DEST if it is a REG; otherwise count things | |
2854 | in SET_DEST because if a register is partially modified, it won't | |
2855 | show up as a potential movable so we don't care how USAGE is set | |
2856 | for it. */ | |
2857 | if (GET_CODE (SET_DEST (x)) != REG) | |
2858 | find_single_use_in_loop (insn, SET_DEST (x), usage); | |
2859 | find_single_use_in_loop (insn, SET_SRC (x), usage); | |
2860 | } | |
2861 | else | |
2862 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2863 | { | |
2864 | if (fmt[i] == 'e' && XEXP (x, i) != 0) | |
2865 | find_single_use_in_loop (insn, XEXP (x, i), usage); | |
2866 | else if (fmt[i] == 'E') | |
2867 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
2868 | find_single_use_in_loop (insn, XVECEXP (x, i, j), usage); | |
2869 | } | |
2870 | } | |
2871 | \f | |
2872 | /* Increment N_TIMES_SET at the index of each register | |
2873 | that is modified by an insn between FROM and TO. | |
2874 | If the value of an element of N_TIMES_SET becomes 127 or more, | |
2875 | stop incrementing it, to avoid overflow. | |
2876 | ||
2877 | Store in SINGLE_USAGE[I] the single insn in which register I is | |
2878 | used, if it is only used once. Otherwise, it is set to 0 (for no | |
2879 | uses) or const0_rtx for more than one use. This parameter may be zero, | |
2880 | in which case this processing is not done. | |
2881 | ||
2882 | Store in *COUNT_PTR the number of actual instruction | |
2883 | in the loop. We use this to decide what is worth moving out. */ | |
2884 | ||
2885 | /* last_set[n] is nonzero iff reg n has been set in the current basic block. | |
2886 | In that case, it is the insn that last set reg n. */ | |
2887 | ||
2888 | static void | |
2889 | count_loop_regs_set (from, to, may_not_move, single_usage, count_ptr, nregs) | |
2890 | register rtx from, to; | |
2891 | char *may_not_move; | |
2892 | rtx *single_usage; | |
2893 | int *count_ptr; | |
2894 | int nregs; | |
2895 | { | |
2896 | register rtx *last_set = (rtx *) alloca (nregs * sizeof (rtx)); | |
2897 | register rtx insn; | |
2898 | register int count = 0; | |
2899 | register rtx dest; | |
2900 | ||
2901 | bzero (last_set, nregs * sizeof (rtx)); | |
2902 | for (insn = from; insn != to; insn = NEXT_INSN (insn)) | |
2903 | { | |
2904 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') | |
2905 | { | |
2906 | ++count; | |
2907 | ||
2908 | /* If requested, record registers that have exactly one use. */ | |
2909 | if (single_usage) | |
2910 | { | |
2911 | find_single_use_in_loop (insn, PATTERN (insn), single_usage); | |
2912 | ||
2913 | /* Include uses in REG_EQUAL notes. */ | |
2914 | if (REG_NOTES (insn)) | |
2915 | find_single_use_in_loop (insn, REG_NOTES (insn), single_usage); | |
2916 | } | |
2917 | ||
2918 | if (GET_CODE (PATTERN (insn)) == CLOBBER | |
2919 | && GET_CODE (XEXP (PATTERN (insn), 0)) == REG) | |
2920 | /* Don't move a reg that has an explicit clobber. | |
2921 | We might do so sometimes, but it's not worth the pain. */ | |
2922 | may_not_move[REGNO (XEXP (PATTERN (insn), 0))] = 1; | |
2923 | ||
2924 | if (GET_CODE (PATTERN (insn)) == SET | |
2925 | || GET_CODE (PATTERN (insn)) == CLOBBER) | |
2926 | { | |
2927 | dest = SET_DEST (PATTERN (insn)); | |
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 this is the first setting of this reg | |
2937 | in current basic block, and it was set before, | |
2938 | it must be set in two basic blocks, so it cannot | |
2939 | be moved out of the loop. */ | |
2940 | if (n_times_set[regno] > 0 && last_set[regno] == 0) | |
2941 | may_not_move[regno] = 1; | |
2942 | /* If this is not first setting in current basic block, | |
2943 | see if reg was used in between previous one and this. | |
2944 | If so, neither one can be moved. */ | |
2945 | if (last_set[regno] != 0 | |
2946 | && reg_used_between_p (dest, last_set[regno], insn)) | |
2947 | may_not_move[regno] = 1; | |
2948 | if (n_times_set[regno] < 127) | |
2949 | ++n_times_set[regno]; | |
2950 | last_set[regno] = insn; | |
2951 | } | |
2952 | } | |
2953 | else if (GET_CODE (PATTERN (insn)) == PARALLEL) | |
2954 | { | |
2955 | register int i; | |
2956 | for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) | |
2957 | { | |
2958 | register rtx x = XVECEXP (PATTERN (insn), 0, i); | |
2959 | if (GET_CODE (x) == CLOBBER && GET_CODE (XEXP (x, 0)) == REG) | |
2960 | /* Don't move a reg that has an explicit clobber. | |
2961 | It's not worth the pain to try to do it correctly. */ | |
2962 | may_not_move[REGNO (XEXP (x, 0))] = 1; | |
2963 | ||
2964 | if (GET_CODE (x) == SET || GET_CODE (x) == CLOBBER) | |
2965 | { | |
2966 | dest = SET_DEST (x); | |
2967 | while (GET_CODE (dest) == SUBREG | |
2968 | || GET_CODE (dest) == ZERO_EXTRACT | |
2969 | || GET_CODE (dest) == SIGN_EXTRACT | |
2970 | || GET_CODE (dest) == STRICT_LOW_PART) | |
2971 | dest = XEXP (dest, 0); | |
2972 | if (GET_CODE (dest) == REG) | |
2973 | { | |
2974 | register int regno = REGNO (dest); | |
2975 | if (n_times_set[regno] > 0 && last_set[regno] == 0) | |
2976 | may_not_move[regno] = 1; | |
2977 | if (last_set[regno] != 0 | |
2978 | && reg_used_between_p (dest, last_set[regno], insn)) | |
2979 | may_not_move[regno] = 1; | |
2980 | if (n_times_set[regno] < 127) | |
2981 | ++n_times_set[regno]; | |
2982 | last_set[regno] = insn; | |
2983 | } | |
2984 | } | |
2985 | } | |
2986 | } | |
2987 | } | |
2988 | if (GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == JUMP_INSN) | |
2989 | bzero (last_set, nregs * sizeof (rtx)); | |
2990 | } | |
2991 | *count_ptr = count; | |
2992 | } | |
2993 | \f | |
2994 | /* Given a loop that is bounded by LOOP_START and LOOP_END | |
2995 | and that is entered at SCAN_START, | |
2996 | return 1 if the register set in SET contained in insn INSN is used by | |
2997 | any insn that precedes INSN in cyclic order starting | |
2998 | from the loop entry point. | |
2999 | ||
3000 | We don't want to use INSN_LUID here because if we restrict INSN to those | |
3001 | that have a valid INSN_LUID, it means we cannot move an invariant out | |
3002 | from an inner loop past two loops. */ | |
3003 | ||
3004 | static int | |
3005 | loop_reg_used_before_p (set, insn, loop_start, scan_start, loop_end) | |
3006 | rtx set, insn, loop_start, scan_start, loop_end; | |
3007 | { | |
3008 | rtx reg = SET_DEST (set); | |
3009 | rtx p; | |
3010 | ||
3011 | /* Scan forward checking for register usage. If we hit INSN, we | |
3012 | are done. Otherwise, if we hit LOOP_END, wrap around to LOOP_START. */ | |
3013 | for (p = scan_start; p != insn; p = NEXT_INSN (p)) | |
3014 | { | |
3015 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i' | |
3016 | && reg_overlap_mentioned_p (reg, PATTERN (p))) | |
3017 | return 1; | |
3018 | ||
3019 | if (p == loop_end) | |
3020 | p = loop_start; | |
3021 | } | |
3022 | ||
3023 | return 0; | |
3024 | } | |
3025 | \f | |
3026 | /* A "basic induction variable" or biv is a pseudo reg that is set | |
3027 | (within this loop) only by incrementing or decrementing it. */ | |
3028 | /* A "general induction variable" or giv is a pseudo reg whose | |
3029 | value is a linear function of a biv. */ | |
3030 | ||
3031 | /* Bivs are recognized by `basic_induction_var'; | |
3032 | Givs by `general_induct_var'. */ | |
3033 | ||
3034 | /* Indexed by register number, indicates whether or not register is an | |
3035 | induction variable, and if so what type. */ | |
3036 | ||
3037 | enum iv_mode *reg_iv_type; | |
3038 | ||
3039 | /* Indexed by register number, contains pointer to `struct induction' | |
3040 | if register is an induction variable. This holds general info for | |
3041 | all induction variables. */ | |
3042 | ||
3043 | struct induction **reg_iv_info; | |
3044 | ||
3045 | /* Indexed by register number, contains pointer to `struct iv_class' | |
3046 | if register is a basic induction variable. This holds info describing | |
3047 | the class (a related group) of induction variables that the biv belongs | |
3048 | to. */ | |
3049 | ||
3050 | struct iv_class **reg_biv_class; | |
3051 | ||
3052 | /* The head of a list which links together (via the next field) | |
3053 | every iv class for the current loop. */ | |
3054 | ||
3055 | struct iv_class *loop_iv_list; | |
3056 | ||
3057 | /* Communication with routines called via `note_stores'. */ | |
3058 | ||
3059 | static rtx note_insn; | |
3060 | ||
3061 | /* Dummy register to have non-zero DEST_REG for DEST_ADDR type givs. */ | |
3062 | ||
3063 | static rtx addr_placeholder; | |
3064 | ||
3065 | /* ??? Unfinished optimizations, and possible future optimizations, | |
3066 | for the strength reduction code. */ | |
3067 | ||
3068 | /* ??? There is one more optimization you might be interested in doing: to | |
3069 | allocate pseudo registers for frequently-accessed memory locations. | |
3070 | If the same memory location is referenced each time around, it might | |
3071 | be possible to copy it into a register before and out after. | |
3072 | This is especially useful when the memory location is a variable which | |
3073 | is in a stack slot because somewhere its address is taken. If the | |
3074 | loop doesn't contain a function call and the variable isn't volatile, | |
3075 | it is safe to keep the value in a register for the duration of the | |
3076 | loop. One tricky thing is that the copying of the value back from the | |
3077 | register has to be done on all exits from the loop. You need to check that | |
3078 | all the exits from the loop go to the same place. */ | |
3079 | ||
3080 | /* ??? The interaction of biv elimination, and recognition of 'constant' | |
3081 | bivs, may cause problems. */ | |
3082 | ||
3083 | /* ??? Add heuristics so that DEST_ADDR strength reduction does not cause | |
3084 | performance problems. | |
3085 | ||
3086 | Perhaps don't eliminate things that can be combined with an addressing | |
3087 | mode. Find all givs that have the same biv, mult_val, and add_val; | |
3088 | then for each giv, check to see if its only use dies in a following | |
3089 | memory address. If so, generate a new memory address and check to see | |
3090 | if it is valid. If it is valid, then store the modified memory address, | |
3091 | otherwise, mark the giv as not done so that it will get its own iv. */ | |
3092 | ||
3093 | /* ??? Could try to optimize branches when it is known that a biv is always | |
3094 | positive. */ | |
3095 | ||
3096 | /* ??? When replace a biv in a compare insn, we should replace with closest | |
3097 | giv so that an optimized branch can still be recognized by the combiner, | |
3098 | e.g. the VAX acb insn. */ | |
3099 | ||
3100 | /* ??? Many of the checks involving uid_luid could be simplified if regscan | |
3101 | was rerun in loop_optimize whenever a register was added or moved. | |
3102 | Also, some of the optimizations could be a little less conservative. */ | |
3103 | \f | |
3104 | /* Perform strength reduction and induction variable elimination. */ | |
3105 | ||
3106 | /* Pseudo registers created during this function will be beyond the last | |
3107 | valid index in several tables including n_times_set and regno_last_uid. | |
3108 | This does not cause a problem here, because the added registers cannot be | |
3109 | givs outside of their loop, and hence will never be reconsidered. | |
3110 | But scan_loop must check regnos to make sure they are in bounds. */ | |
3111 | ||
3112 | static void | |
3113 | strength_reduce (scan_start, end, loop_top, insn_count, | |
3114 | loop_start, loop_end) | |
3115 | rtx scan_start; | |
3116 | rtx end; | |
3117 | rtx loop_top; | |
3118 | int insn_count; | |
3119 | rtx loop_start; | |
3120 | rtx loop_end; | |
3121 | { | |
3122 | rtx p; | |
3123 | rtx set; | |
3124 | rtx inc_val; | |
3125 | rtx mult_val; | |
3126 | rtx dest_reg; | |
3127 | /* This is 1 if current insn is not executed at least once for every loop | |
3128 | iteration. */ | |
3129 | int not_every_iteration = 0; | |
3130 | /* This is 1 if current insn may be executed more than once for every | |
3131 | loop iteration. */ | |
3132 | int maybe_multiple = 0; | |
3133 | /* Temporary list pointers for traversing loop_iv_list. */ | |
3134 | struct iv_class *bl, **backbl; | |
3135 | /* Ratio of extra register life span we can justify | |
3136 | for saving an instruction. More if loop doesn't call subroutines | |
3137 | since in that case saving an insn makes more difference | |
3138 | and more registers are available. */ | |
3139 | /* ??? could set this to last value of threshold in move_movables */ | |
3140 | int threshold = (loop_has_call ? 1 : 2) * (3 + n_non_fixed_regs); | |
3141 | /* Map of pseudo-register replacements. */ | |
3142 | rtx *reg_map; | |
3143 | int call_seen; | |
3144 | rtx test; | |
3145 | rtx end_insert_before; | |
3146 | ||
3147 | reg_iv_type = (enum iv_mode *) alloca (max_reg_before_loop | |
3148 | * sizeof (enum iv_mode *)); | |
3149 | bzero ((char *) reg_iv_type, max_reg_before_loop * sizeof (enum iv_mode *)); | |
3150 | reg_iv_info = (struct induction **) | |
3151 | alloca (max_reg_before_loop * sizeof (struct induction *)); | |
3152 | bzero ((char *) reg_iv_info, (max_reg_before_loop | |
3153 | * sizeof (struct induction *))); | |
3154 | reg_biv_class = (struct iv_class **) | |
3155 | alloca (max_reg_before_loop * sizeof (struct iv_class *)); | |
3156 | bzero ((char *) reg_biv_class, (max_reg_before_loop | |
3157 | * sizeof (struct iv_class *))); | |
3158 | ||
3159 | loop_iv_list = 0; | |
3160 | addr_placeholder = gen_reg_rtx (Pmode); | |
3161 | ||
3162 | /* Save insn immediately after the loop_end. Insns inserted after loop_end | |
3163 | must be put before this insn, so that they will appear in the right | |
3164 | order (i.e. loop order). | |
3165 | ||
3166 | If loop_end is the end of the current function, then emit a | |
3167 | NOTE_INSN_DELETED after loop_end and set end_insert_before to the | |
3168 | dummy note insn. */ | |
3169 | if (NEXT_INSN (loop_end) != 0) | |
3170 | end_insert_before = NEXT_INSN (loop_end); | |
3171 | else | |
3172 | end_insert_before = emit_note_after (NOTE_INSN_DELETED, loop_end); | |
3173 | ||
3174 | /* Scan through loop to find all possible bivs. */ | |
3175 | ||
3176 | p = scan_start; | |
3177 | while (1) | |
3178 | { | |
3179 | p = NEXT_INSN (p); | |
3180 | /* At end of a straight-in loop, we are done. | |
3181 | At end of a loop entered at the bottom, scan the top. */ | |
3182 | if (p == scan_start) | |
3183 | break; | |
3184 | if (p == end) | |
3185 | { | |
3186 | if (loop_top != 0) | |
3187 | p = NEXT_INSN (loop_top); | |
3188 | else | |
3189 | break; | |
3190 | if (p == scan_start) | |
3191 | break; | |
3192 | } | |
3193 | ||
3194 | if (GET_CODE (p) == INSN | |
3195 | && (set = single_set (p)) | |
3196 | && GET_CODE (SET_DEST (set)) == REG) | |
3197 | { | |
3198 | dest_reg = SET_DEST (set); | |
3199 | if (REGNO (dest_reg) < max_reg_before_loop | |
3200 | && REGNO (dest_reg) >= FIRST_PSEUDO_REGISTER | |
3201 | && reg_iv_type[REGNO (dest_reg)] != NOT_BASIC_INDUCT) | |
3202 | { | |
3203 | if (basic_induction_var (SET_SRC (set), dest_reg, p, | |
3204 | &inc_val, &mult_val)) | |
3205 | { | |
3206 | /* It is a possible basic induction variable. | |
3207 | Create and initialize an induction structure for it. */ | |
3208 | ||
3209 | struct induction *v | |
3210 | = (struct induction *) alloca (sizeof (struct induction)); | |
3211 | ||
3212 | record_biv (v, p, dest_reg, inc_val, mult_val, | |
3213 | not_every_iteration, maybe_multiple); | |
3214 | reg_iv_type[REGNO (dest_reg)] = BASIC_INDUCT; | |
3215 | } | |
3216 | else if (REGNO (dest_reg) < max_reg_before_loop) | |
3217 | reg_iv_type[REGNO (dest_reg)] = NOT_BASIC_INDUCT; | |
3218 | } | |
3219 | } | |
3220 | ||
3221 | /* Past CODE_LABEL, we get to insns that may be executed multiple | |
3222 | times. The only way we can be sure that they can't is if every | |
3223 | every jump insn between here and the end of the loop either | |
3224 | returns, exits the loop, or is a forward jump. */ | |
3225 | ||
3226 | if (GET_CODE (p) == CODE_LABEL) | |
3227 | { | |
3228 | rtx insn = p; | |
3229 | ||
3230 | maybe_multiple = 0; | |
3231 | ||
3232 | while (1) | |
3233 | { | |
3234 | insn = NEXT_INSN (insn); | |
3235 | if (insn == scan_start) | |
3236 | break; | |
3237 | if (insn == end) | |
3238 | { | |
3239 | if (loop_top != 0) | |
3240 | insn = NEXT_INSN (loop_top); | |
3241 | else | |
3242 | break; | |
3243 | if (insn == scan_start) | |
3244 | break; | |
3245 | } | |
3246 | ||
3247 | if (GET_CODE (insn) == JUMP_INSN | |
3248 | && GET_CODE (PATTERN (insn)) != RETURN | |
3249 | && (! condjump_p (insn) | |
3250 | || (JUMP_LABEL (insn) != 0 | |
3251 | && (INSN_UID (JUMP_LABEL (insn)) >= max_uid_for_loop | |
3252 | || INSN_UID (insn) >= max_uid_for_loop | |
3253 | || (INSN_LUID (JUMP_LABEL (insn)) | |
3254 | < INSN_LUID (insn)))))) | |
3255 | { | |
3256 | maybe_multiple = 1; | |
3257 | break; | |
3258 | } | |
3259 | } | |
3260 | } | |
3261 | ||
3262 | /* Past a label or a jump, we get to insns for which we can't count | |
3263 | on whether or how many times they will be executed during each | |
3264 | iteration. */ | |
3265 | /* This code appears in three places, once in scan_loop, and twice | |
3266 | in strength_reduce. */ | |
3267 | if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) | |
3268 | /* If we enter the loop in the middle, and scan around to the | |
3269 | beginning, don't set not_every_iteration for that. | |
3270 | This can be any kind of jump, since we want to know if insns | |
3271 | will be executed if the loop is executed. */ | |
3272 | && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top | |
3273 | && ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p)) | |
3274 | || (NEXT_INSN (p) == loop_end && condjump_p (p))))) | |
3275 | not_every_iteration = 1; | |
3276 | ||
3277 | /* At the virtual top of a converted loop, insns are again known to | |
3278 | be executed each iteration: logically, the loop begins here | |
3279 | even though the exit code has been duplicated. */ | |
3280 | ||
3281 | else if (GET_CODE (p) == NOTE | |
3282 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP) | |
3283 | not_every_iteration = 0; | |
3284 | ||
3285 | /* Unlike in the code motion pass where MAYBE_NEVER indicates that | |
3286 | an insn may never be executed, NOT_EVERY_ITERATION indicates whether | |
3287 | or not an insn is known to be executed each iteration of the | |
3288 | loop, whether or not any iterations are known to occur. | |
3289 | ||
3290 | Therefore, if we have just passed a label and have no more labels | |
3291 | between here and the test insn of the loop, we know these insns | |
3292 | will be executed each iteration. This can also happen if we | |
3293 | have just passed a jump, for example, when there are nested loops. */ | |
3294 | ||
3295 | if (not_every_iteration && GET_CODE (p) == CODE_LABEL | |
3296 | && no_labels_between_p (p, loop_end)) | |
3297 | not_every_iteration = 0; | |
3298 | } | |
3299 | ||
3300 | /* Scan loop_iv_list to remove all regs that proved not to be bivs. | |
3301 | Make a sanity check against n_times_set. */ | |
3302 | for (backbl = &loop_iv_list, bl = *backbl; bl; bl = bl->next) | |
3303 | { | |
3304 | if (reg_iv_type[bl->regno] != BASIC_INDUCT | |
3305 | /* Above happens if register modified by subreg, etc. */ | |
3306 | /* Make sure it is not recognized as a basic induction var: */ | |
3307 | || n_times_set[bl->regno] != bl->biv_count | |
3308 | /* If never incremented, it is invariant that we decided not to | |
3309 | move. So leave it alone. */ | |
3310 | || ! bl->incremented) | |
3311 | { | |
3312 | if (loop_dump_stream) | |
3313 | fprintf (loop_dump_stream, "Reg %d: biv discarded, %s\n", | |
3314 | bl->regno, | |
3315 | (reg_iv_type[bl->regno] != BASIC_INDUCT | |
3316 | ? "not induction variable" | |
3317 | : (! bl->incremented ? "never incremented" | |
3318 | : "count error"))); | |
3319 | ||
3320 | reg_iv_type[bl->regno] = NOT_BASIC_INDUCT; | |
3321 | *backbl = bl->next; | |
3322 | } | |
3323 | else | |
3324 | { | |
3325 | backbl = &bl->next; | |
3326 | ||
3327 | if (loop_dump_stream) | |
3328 | fprintf (loop_dump_stream, "Reg %d: biv verified\n", bl->regno); | |
3329 | } | |
3330 | } | |
3331 | ||
3332 | /* Exit if there are no bivs. */ | |
3333 | if (! loop_iv_list) | |
3334 | { | |
3335 | /* Can still unroll the loop anyways, but indicate that there is no | |
3336 | strength reduction info available. */ | |
3337 | if (flag_unroll_loops) | |
3338 | unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 0); | |
3339 | ||
3340 | return; | |
3341 | } | |
3342 | ||
3343 | /* Find initial value for each biv by searching backwards from loop_start, | |
3344 | halting at first label. Also record any test condition. */ | |
3345 | ||
3346 | call_seen = 0; | |
3347 | for (p = loop_start; p && GET_CODE (p) != CODE_LABEL; p = PREV_INSN (p)) | |
3348 | { | |
3349 | note_insn = p; | |
3350 | ||
3351 | if (GET_CODE (p) == CALL_INSN) | |
3352 | call_seen = 1; | |
3353 | ||
3354 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
3355 | || GET_CODE (p) == CALL_INSN) | |
3356 | note_stores (PATTERN (p), record_initial); | |
3357 | ||
3358 | /* Record any test of a biv that branches around the loop if no store | |
3359 | between it and the start of loop. We only care about tests with | |
3360 | constants and registers and only certain of those. */ | |
3361 | if (GET_CODE (p) == JUMP_INSN | |
3362 | && JUMP_LABEL (p) != 0 | |
3363 | && next_real_insn (JUMP_LABEL (p)) == next_real_insn (loop_end) | |
3364 | && (test = get_condition_for_loop (p)) != 0 | |
3365 | && GET_CODE (XEXP (test, 0)) == REG | |
3366 | && REGNO (XEXP (test, 0)) < max_reg_before_loop | |
3367 | && (bl = reg_biv_class[REGNO (XEXP (test, 0))]) != 0 | |
3368 | && valid_initial_value_p (XEXP (test, 1), p, call_seen, loop_start) | |
3369 | && bl->init_insn == 0) | |
3370 | { | |
3371 | /* If an NE test, we have an initial value! */ | |
3372 | if (GET_CODE (test) == NE) | |
3373 | { | |
3374 | bl->init_insn = p; | |
3375 | bl->init_set = gen_rtx (SET, VOIDmode, | |
3376 | XEXP (test, 0), XEXP (test, 1)); | |
3377 | } | |
3378 | else | |
3379 | bl->initial_test = test; | |
3380 | } | |
3381 | } | |
3382 | ||
3383 | /* Look at the each biv and see if we can say anything better about its | |
3384 | initial value from any initializing insns set up above. (This is done | |
3385 | in two passes to avoid missing SETs in a PARALLEL.) */ | |
3386 | for (bl = loop_iv_list; bl; bl = bl->next) | |
3387 | { | |
3388 | rtx src; | |
3389 | ||
3390 | if (! bl->init_insn) | |
3391 | continue; | |
3392 | ||
3393 | src = SET_SRC (bl->init_set); | |
3394 | ||
3395 | if (loop_dump_stream) | |
3396 | fprintf (loop_dump_stream, | |
3397 | "Biv %d initialized at insn %d: initial value ", | |
3398 | bl->regno, INSN_UID (bl->init_insn)); | |
3399 | ||
3400 | if (valid_initial_value_p (src, bl->init_insn, call_seen, loop_start)) | |
3401 | { | |
3402 | bl->initial_value = src; | |
3403 | ||
3404 | if (loop_dump_stream) | |
3405 | { | |
3406 | if (GET_CODE (src) == CONST_INT) | |
3407 | fprintf (loop_dump_stream, "%d\n", INTVAL (src)); | |
3408 | else | |
3409 | { | |
3410 | print_rtl (loop_dump_stream, src); | |
3411 | fprintf (loop_dump_stream, "\n"); | |
3412 | } | |
3413 | } | |
3414 | } | |
3415 | else | |
3416 | { | |
3417 | /* Biv initial value is not simple move, | |
3418 | so let it keep initial value of "itself". */ | |
3419 | ||
3420 | if (loop_dump_stream) | |
3421 | fprintf (loop_dump_stream, "is complex\n"); | |
3422 | } | |
3423 | } | |
3424 | ||
3425 | /* Search the loop for general induction variables. */ | |
3426 | ||
3427 | /* A register is a giv if: it is only set once, it is a function of a | |
3428 | biv and a constant (or invariant), and it is not a biv. */ | |
3429 | ||
3430 | not_every_iteration = 0; | |
3431 | p = scan_start; | |
3432 | while (1) | |
3433 | { | |
3434 | p = NEXT_INSN (p); | |
3435 | /* At end of a straight-in loop, we are done. | |
3436 | At end of a loop entered at the bottom, scan the top. */ | |
3437 | if (p == scan_start) | |
3438 | break; | |
3439 | if (p == end) | |
3440 | { | |
3441 | if (loop_top != 0) | |
3442 | p = NEXT_INSN (loop_top); | |
3443 | else | |
3444 | break; | |
3445 | if (p == scan_start) | |
3446 | break; | |
3447 | } | |
3448 | ||
3449 | /* Look for a general induction variable in a register. */ | |
3450 | if (GET_CODE (p) == INSN | |
3451 | && (set = single_set (p)) | |
3452 | && GET_CODE (SET_DEST (set)) == REG | |
3453 | && ! may_not_optimize[REGNO (SET_DEST (set))]) | |
3454 | { | |
3455 | rtx src_reg; | |
3456 | rtx add_val; | |
3457 | rtx mult_val; | |
3458 | int benefit; | |
3459 | rtx regnote = 0; | |
3460 | ||
3461 | dest_reg = SET_DEST (set); | |
3462 | if (REGNO (dest_reg) < FIRST_PSEUDO_REGISTER) | |
3463 | continue; | |
3464 | ||
3465 | if (/* SET_SRC is a giv. */ | |
3466 | ((benefit = general_induction_var (SET_SRC (set), | |
3467 | &src_reg, &add_val, | |
3468 | &mult_val)) | |
3469 | /* Equivalent expression is a giv. */ | |
3470 | || ((regnote = find_reg_note (p, REG_EQUAL, NULL_RTX)) | |
3471 | && (benefit = general_induction_var (XEXP (regnote, 0), | |
3472 | &src_reg, | |
3473 | &add_val, &mult_val)))) | |
3474 | /* Don't try to handle any regs made by loop optimization. | |
3475 | We have nothing on them in regno_first_uid, etc. */ | |
3476 | && REGNO (dest_reg) < max_reg_before_loop | |
3477 | /* Don't recognize a BASIC_INDUCT_VAR here. */ | |
3478 | && dest_reg != src_reg | |
3479 | /* This must be the only place where the register is set. */ | |
3480 | && (n_times_set[REGNO (dest_reg)] == 1 | |
3481 | /* or all sets must be consecutive and make a giv. */ | |
3482 | || (benefit = consec_sets_giv (benefit, p, | |
3483 | src_reg, dest_reg, | |
3484 | &add_val, &mult_val)))) | |
3485 | { | |
3486 | int count; | |
3487 | struct induction *v | |
3488 | = (struct induction *) alloca (sizeof (struct induction)); | |
3489 | rtx temp; | |
3490 | ||
3491 | /* If this is a library call, increase benefit. */ | |
3492 | if (find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
3493 | benefit += libcall_benefit (p); | |
3494 | ||
3495 | /* Skip the consecutive insns, if there are any. */ | |
3496 | for (count = n_times_set[REGNO (dest_reg)] - 1; | |
3497 | count > 0; count--) | |
3498 | { | |
3499 | /* If first insn of libcall sequence, skip to end. | |
3500 | Do this at start of loop, since INSN is guaranteed to | |
3501 | be an insn here. */ | |
3502 | if (GET_CODE (p) != NOTE | |
3503 | && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
3504 | p = XEXP (temp, 0); | |
3505 | ||
3506 | do p = NEXT_INSN (p); | |
3507 | while (GET_CODE (p) == NOTE); | |
3508 | } | |
3509 | ||
3510 | record_giv (v, p, src_reg, dest_reg, mult_val, add_val, benefit, | |
3511 | DEST_REG, not_every_iteration, NULL_PTR, loop_start, | |
3512 | loop_end); | |
3513 | ||
3514 | } | |
3515 | } | |
3516 | ||
3517 | #ifndef DONT_REDUCE_ADDR | |
3518 | /* Look for givs which are memory addresses. */ | |
3519 | /* This resulted in worse code on a VAX 8600. I wonder if it | |
3520 | still does. */ | |
3521 | if (GET_CODE (p) == INSN) | |
3522 | find_mem_givs (PATTERN (p), p, not_every_iteration, loop_start, | |
3523 | loop_end); | |
3524 | #endif | |
3525 | ||
3526 | /* Update the status of whether giv can derive other givs. This can | |
3527 | change when we pass a label or an insn that updates a biv. */ | |
3528 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
3529 | || GET_CODE (p) == CODE_LABEL) | |
3530 | update_giv_derive (p); | |
3531 | ||
3532 | /* Past a label or a jump, we get to insns for which we can't count | |
3533 | on whether or how many times they will be executed during each | |
3534 | iteration. */ | |
3535 | /* This code appears in three places, once in scan_loop, and twice | |
3536 | in strength_reduce. */ | |
3537 | if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN) | |
3538 | /* If we enter the loop in the middle, and scan around | |
3539 | to the beginning, don't set not_every_iteration for that. | |
3540 | This can be any kind of jump, since we want to know if insns | |
3541 | will be executed if the loop is executed. */ | |
3542 | && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top | |
3543 | && ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p)) | |
3544 | || (NEXT_INSN (p) == loop_end && condjump_p (p))))) | |
3545 | not_every_iteration = 1; | |
3546 | ||
3547 | /* At the virtual top of a converted loop, insns are again known to | |
3548 | be executed each iteration: logically, the loop begins here | |
3549 | even though the exit code has been duplicated. */ | |
3550 | ||
3551 | else if (GET_CODE (p) == NOTE | |
3552 | && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP) | |
3553 | not_every_iteration = 0; | |
3554 | ||
3555 | /* Unlike in the code motion pass where MAYBE_NEVER indicates that | |
3556 | an insn may never be executed, NOT_EVERY_ITERATION indicates whether | |
3557 | or not an insn is known to be executed each iteration of the | |
3558 | loop, whether or not any iterations are known to occur. | |
3559 | ||
3560 | Therefore, if we have just passed a label and have no more labels | |
3561 | between here and the test insn of the loop, we know these insns | |
3562 | will be executed each iteration. */ | |
3563 | ||
3564 | if (not_every_iteration && GET_CODE (p) == CODE_LABEL | |
3565 | && no_labels_between_p (p, loop_end)) | |
3566 | not_every_iteration = 0; | |
3567 | } | |
3568 | ||
3569 | /* Try to calculate and save the number of loop iterations. This is | |
3570 | set to zero if the actual number can not be calculated. This must | |
3571 | be called after all giv's have been identified, since otherwise it may | |
3572 | fail if the iteration variable is a giv. */ | |
3573 | ||
3574 | loop_n_iterations = loop_iterations (loop_start, loop_end); | |
3575 | ||
3576 | /* Now for each giv for which we still don't know whether or not it is | |
3577 | replaceable, check to see if it is replaceable because its final value | |
3578 | can be calculated. This must be done after loop_iterations is called, | |
3579 | so that final_giv_value will work correctly. */ | |
3580 | ||
3581 | for (bl = loop_iv_list; bl; bl = bl->next) | |
3582 | { | |
3583 | struct induction *v; | |
3584 | ||
3585 | for (v = bl->giv; v; v = v->next_iv) | |
3586 | if (! v->replaceable && ! v->not_replaceable) | |
3587 | check_final_value (v, loop_start, loop_end); | |
3588 | } | |
3589 | ||
3590 | /* Try to prove that the loop counter variable (if any) is always | |
3591 | nonnegative; if so, record that fact with a REG_NONNEG note | |
3592 | so that "decrement and branch until zero" insn can be used. */ | |
3593 | check_dbra_loop (loop_end, insn_count, loop_start); | |
3594 | ||
3595 | /* Create reg_map to hold substitutions for replaceable giv regs. */ | |
3596 | reg_map = (rtx *) alloca (max_reg_before_loop * sizeof (rtx)); | |
3597 | bzero ((char *) reg_map, max_reg_before_loop * sizeof (rtx)); | |
3598 | ||
3599 | /* Examine each iv class for feasibility of strength reduction/induction | |
3600 | variable elimination. */ | |
3601 | ||
3602 | for (bl = loop_iv_list; bl; bl = bl->next) | |
3603 | { | |
3604 | struct induction *v; | |
3605 | int benefit; | |
3606 | int all_reduced; | |
3607 | rtx final_value = 0; | |
3608 | ||
3609 | /* Test whether it will be possible to eliminate this biv | |
3610 | provided all givs are reduced. This is possible if either | |
3611 | the reg is not used outside the loop, or we can compute | |
3612 | what its final value will be. | |
3613 | ||
3614 | For architectures with a decrement_and_branch_until_zero insn, | |
3615 | don't do this if we put a REG_NONNEG note on the endtest for | |
3616 | this biv. */ | |
3617 | ||
3618 | /* Compare against bl->init_insn rather than loop_start. | |
3619 | We aren't concerned with any uses of the biv between | |
3620 | init_insn and loop_start since these won't be affected | |
3621 | by the value of the biv elsewhere in the function, so | |
3622 | long as init_insn doesn't use the biv itself. | |
3623 | March 14, 1989 -- self@bayes.arc.nasa.gov */ | |
3624 | ||
3625 | if ((uid_luid[regno_last_uid[bl->regno]] < INSN_LUID (loop_end) | |
3626 | && bl->init_insn | |
3627 | && INSN_UID (bl->init_insn) < max_uid_for_loop | |
3628 | && uid_luid[regno_first_uid[bl->regno]] >= INSN_LUID (bl->init_insn) | |
3629 | #ifdef HAVE_decrement_and_branch_until_zero | |
3630 | && ! bl->nonneg | |
3631 | #endif | |
3632 | && ! reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set))) | |
3633 | || ((final_value = final_biv_value (bl, loop_start, loop_end)) | |
3634 | #ifdef HAVE_decrement_and_branch_until_zero | |
3635 | && ! bl->nonneg | |
3636 | #endif | |
3637 | )) | |
3638 | bl->eliminable = maybe_eliminate_biv (bl, loop_start, end, 0, | |
3639 | threshold, insn_count); | |
3640 | else | |
3641 | { | |
3642 | if (loop_dump_stream) | |
3643 | { | |
3644 | fprintf (loop_dump_stream, | |
3645 | "Cannot eliminate biv %d.\n", | |
3646 | bl->regno); | |
3647 | fprintf (loop_dump_stream, | |
3648 | "First use: insn %d, last use: insn %d.\n", | |
3649 | regno_first_uid[bl->regno], | |
3650 | regno_last_uid[bl->regno]); | |
3651 | } | |
3652 | } | |
3653 | ||
3654 | /* Combine all giv's for this iv_class. */ | |
3655 | combine_givs (bl); | |
3656 | ||
3657 | /* This will be true at the end, if all givs which depend on this | |
3658 | biv have been strength reduced. | |
3659 | We can't (currently) eliminate the biv unless this is so. */ | |
3660 | all_reduced = 1; | |
3661 | ||
3662 | /* Check each giv in this class to see if we will benefit by reducing | |
3663 | it. Skip giv's combined with others. */ | |
3664 | for (v = bl->giv; v; v = v->next_iv) | |
3665 | { | |
3666 | struct induction *tv; | |
3667 | ||
3668 | if (v->ignore || v->same) | |
3669 | continue; | |
3670 | ||
3671 | benefit = v->benefit; | |
3672 | ||
3673 | /* Reduce benefit if not replaceable, since we will insert | |
3674 | a move-insn to replace the insn that calculates this giv. | |
3675 | Don't do this unless the giv is a user variable, since it | |
3676 | will often be marked non-replaceable because of the duplication | |
3677 | of the exit code outside the loop. In such a case, the copies | |
3678 | we insert are dead and will be deleted. So they don't have | |
3679 | a cost. Similar situations exist. */ | |
3680 | /* ??? The new final_[bg]iv_value code does a much better job | |
3681 | of finding replaceable giv's, and hence this code may no longer | |
3682 | be necessary. */ | |
3683 | if (! v->replaceable && ! bl->eliminable | |
3684 | && REG_USERVAR_P (v->dest_reg)) | |
3685 | benefit -= copy_cost; | |
3686 | ||
3687 | /* Decrease the benefit to count the add-insns that we will | |
3688 | insert to increment the reduced reg for the giv. */ | |
3689 | benefit -= add_cost * bl->biv_count; | |
3690 | ||
3691 | /* Decide whether to strength-reduce this giv or to leave the code | |
3692 | unchanged (recompute it from the biv each time it is used). | |
3693 | This decision can be made independently for each giv. */ | |
3694 | ||
3695 | /* ??? Perhaps attempt to guess whether autoincrement will handle | |
3696 | some of the new add insns; if so, can increase BENEFIT | |
3697 | (undo the subtraction of add_cost that was done above). */ | |
3698 | ||
3699 | /* If an insn is not to be strength reduced, then set its ignore | |
3700 | flag, and clear all_reduced. */ | |
3701 | ||
3702 | if (v->lifetime * threshold * benefit < insn_count) | |
3703 | { | |
3704 | if (loop_dump_stream) | |
3705 | fprintf (loop_dump_stream, | |
3706 | "giv of insn %d not worth while, %d vs %d.\n", | |
3707 | INSN_UID (v->insn), | |
3708 | v->lifetime * threshold * benefit, insn_count); | |
3709 | v->ignore = 1; | |
3710 | all_reduced = 0; | |
3711 | } | |
3712 | else | |
3713 | { | |
3714 | /* Check that we can increment the reduced giv without a | |
3715 | multiply insn. If not, reject it. */ | |
3716 | ||
3717 | for (tv = bl->biv; tv; tv = tv->next_iv) | |
3718 | if (tv->mult_val == const1_rtx | |
3719 | && ! product_cheap_p (tv->add_val, v->mult_val)) | |
3720 | { | |
3721 | if (loop_dump_stream) | |
3722 | fprintf (loop_dump_stream, | |
3723 | "giv of insn %d: would need a multiply.\n", | |
3724 | INSN_UID (v->insn)); | |
3725 | v->ignore = 1; | |
3726 | all_reduced = 0; | |
3727 | break; | |
3728 | } | |
3729 | } | |
3730 | } | |
3731 | ||
3732 | /* Reduce each giv that we decided to reduce. */ | |
3733 | ||
3734 | for (v = bl->giv; v; v = v->next_iv) | |
3735 | { | |
3736 | struct induction *tv; | |
3737 | if (! v->ignore && v->same == 0) | |
3738 | { | |
3739 | v->new_reg = gen_reg_rtx (v->mode); | |
3740 | ||
3741 | /* For each place where the biv is incremented, | |
3742 | add an insn to increment the new, reduced reg for the giv. */ | |
3743 | for (tv = bl->biv; tv; tv = tv->next_iv) | |
3744 | { | |
3745 | if (tv->mult_val == const1_rtx) | |
3746 | emit_iv_add_mult (tv->add_val, v->mult_val, | |
3747 | v->new_reg, v->new_reg, tv->insn); | |
3748 | else /* tv->mult_val == const0_rtx */ | |
3749 | /* A multiply is acceptable here | |
3750 | since this is presumed to be seldom executed. */ | |
3751 | emit_iv_add_mult (tv->add_val, v->mult_val, | |
3752 | v->add_val, v->new_reg, tv->insn); | |
3753 | } | |
3754 | ||
3755 | /* Add code at loop start to initialize giv's reduced reg. */ | |
3756 | ||
3757 | emit_iv_add_mult (bl->initial_value, v->mult_val, | |
3758 | v->add_val, v->new_reg, loop_start); | |
3759 | } | |
3760 | } | |
3761 | ||
3762 | /* Rescan all givs. If a giv is the same as a giv not reduced, mark it | |
3763 | as not reduced. | |
3764 | ||
3765 | For each giv register that can be reduced now: if replaceable, | |
3766 | substitute reduced reg wherever the old giv occurs; | |
3767 | else add new move insn "giv_reg = reduced_reg". | |
3768 | ||
3769 | Also check for givs whose first use is their definition and whose | |
3770 | last use is the definition of another giv. If so, it is likely | |
3771 | dead and should not be used to eliminate a biv. */ | |
3772 | for (v = bl->giv; v; v = v->next_iv) | |
3773 | { | |
3774 | if (v->same && v->same->ignore) | |
3775 | v->ignore = 1; | |
3776 | ||
3777 | if (v->ignore) | |
3778 | continue; | |
3779 | ||
3780 | if (v->giv_type == DEST_REG | |
3781 | && regno_first_uid[REGNO (v->dest_reg)] == INSN_UID (v->insn)) | |
3782 | { | |
3783 | struct induction *v1; | |
3784 | ||
3785 | for (v1 = bl->giv; v1; v1 = v1->next_iv) | |
3786 | if (regno_last_uid[REGNO (v->dest_reg)] == INSN_UID (v1->insn)) | |
3787 | v->maybe_dead = 1; | |
3788 | } | |
3789 | ||
3790 | /* Update expression if this was combined, in case other giv was | |
3791 | replaced. */ | |
3792 | if (v->same) | |
3793 | v->new_reg = replace_rtx (v->new_reg, | |
3794 | v->same->dest_reg, v->same->new_reg); | |
3795 | ||
3796 | if (v->giv_type == DEST_ADDR) | |
3797 | /* Store reduced reg as the address in the memref where we found | |
3798 | this giv. */ | |
3799 | *v->location = v->new_reg; | |
3800 | else if (v->replaceable) | |
3801 | { | |
3802 | reg_map[REGNO (v->dest_reg)] = v->new_reg; | |
3803 | ||
3804 | #if 0 | |
3805 | /* I can no longer duplicate the original problem. Perhaps | |
3806 | this is unnecessary now? */ | |
3807 | ||
3808 | /* Replaceable; it isn't strictly necessary to delete the old | |
3809 | insn and emit a new one, because v->dest_reg is now dead. | |
3810 | ||
3811 | However, especially when unrolling loops, the special | |
3812 | handling for (set REG0 REG1) in the second cse pass may | |
3813 | make v->dest_reg live again. To avoid this problem, emit | |
3814 | an insn to set the original giv reg from the reduced giv. | |
3815 | We can not delete the original insn, since it may be part | |
3816 | of a LIBCALL, and the code in flow that eliminates dead | |
3817 | libcalls will fail if it is deleted. */ | |
3818 | emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg), | |
3819 | v->insn); | |
3820 | #endif | |
3821 | } | |
3822 | else | |
3823 | { | |
3824 | /* Not replaceable; emit an insn to set the original giv reg from | |
3825 | the reduced giv, same as above. */ | |
3826 | emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg), | |
3827 | v->insn); | |
3828 | } | |
3829 | ||
3830 | /* When a loop is reversed, givs which depend on the reversed | |
3831 | biv, and which are live outside the loop, must be set to their | |
3832 | correct final value. This insn is only needed if the giv is | |
3833 | not replaceable. The correct final value is the same as the | |
3834 | value that the giv starts the reversed loop with. */ | |
3835 | if (bl->reversed && ! v->replaceable) | |
3836 | emit_iv_add_mult (bl->initial_value, v->mult_val, | |
3837 | v->add_val, v->dest_reg, end_insert_before); | |
3838 | else if (v->final_value) | |
3839 | { | |
3840 | rtx insert_before; | |
3841 | ||
3842 | /* If the loop has multiple exits, emit the insn before the | |
3843 | loop to ensure that it will always be executed no matter | |
3844 | how the loop exits. Otherwise, emit the insn after the loop, | |
3845 | since this is slightly more efficient. */ | |
3846 | if (loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
3847 | insert_before = loop_start; | |
3848 | else | |
3849 | insert_before = end_insert_before; | |
3850 | emit_insn_before (gen_move_insn (v->dest_reg, v->final_value), | |
3851 | insert_before); | |
3852 | ||
3853 | #if 0 | |
3854 | /* If the insn to set the final value of the giv was emitted | |
3855 | before the loop, then we must delete the insn inside the loop | |
3856 | that sets it. If this is a LIBCALL, then we must delete | |
3857 | every insn in the libcall. Note, however, that | |
3858 | final_giv_value will only succeed when there are multiple | |
3859 | exits if the giv is dead at each exit, hence it does not | |
3860 | matter that the original insn remains because it is dead | |
3861 | anyways. */ | |
3862 | /* Delete the insn inside the loop that sets the giv since | |
3863 | the giv is now set before (or after) the loop. */ | |
3864 | delete_insn (v->insn); | |
3865 | #endif | |
3866 | } | |
3867 | ||
3868 | if (loop_dump_stream) | |
3869 | { | |
3870 | fprintf (loop_dump_stream, "giv at %d reduced to ", | |
3871 | INSN_UID (v->insn)); | |
3872 | print_rtl (loop_dump_stream, v->new_reg); | |
3873 | fprintf (loop_dump_stream, "\n"); | |
3874 | } | |
3875 | } | |
3876 | ||
3877 | /* All the givs based on the biv bl have been reduced if they | |
3878 | merit it. */ | |
3879 | ||
3880 | /* For each giv not marked as maybe dead that has been combined with a | |
3881 | second giv, clear any "maybe dead" mark on that second giv. | |
3882 | v->new_reg will either be or refer to the register of the giv it | |
3883 | combined with. | |
3884 | ||
3885 | Doing this clearing avoids problems in biv elimination where a | |
3886 | giv's new_reg is a complex value that can't be put in the insn but | |
3887 | the giv combined with (with a reg as new_reg) is marked maybe_dead. | |
3888 | Since the register will be used in either case, we'd prefer it be | |
3889 | used from the simpler giv. */ | |
3890 | ||
3891 | for (v = bl->giv; v; v = v->next_iv) | |
3892 | if (! v->maybe_dead && v->same) | |
3893 | v->same->maybe_dead = 0; | |
3894 | ||
3895 | /* Try to eliminate the biv, if it is a candidate. | |
3896 | This won't work if ! all_reduced, | |
3897 | since the givs we planned to use might not have been reduced. | |
3898 | ||
3899 | We have to be careful that we didn't initially think we could eliminate | |
3900 | this biv because of a giv that we now think may be dead and shouldn't | |
3901 | be used as a biv replacement. | |
3902 | ||
3903 | Also, there is the possibility that we may have a giv that looks | |
3904 | like it can be used to eliminate a biv, but the resulting insn | |
3905 | isn't valid. This can happen, for example, on the 88k, where a | |
3906 | JUMP_INSN can compare a register only with zero. Attempts to | |
3907 | replace it with a compare with a constant will fail. | |
3908 | ||
3909 | Note that in cases where this call fails, we may have replaced some | |
3910 | of the occurrences of the biv with a giv, but no harm was done in | |
3911 | doing so in the rare cases where it can occur. */ | |
3912 | ||
3913 | if (all_reduced == 1 && bl->eliminable | |
3914 | && maybe_eliminate_biv (bl, loop_start, end, 1, | |
3915 | threshold, insn_count)) | |
3916 | ||
3917 | { | |
3918 | /* ?? If we created a new test to bypass the loop entirely, | |
3919 | or otherwise drop straight in, based on this test, then | |
3920 | we might want to rewrite it also. This way some later | |
3921 | pass has more hope of removing the initialization of this | |
3922 | biv entirely. */ | |
3923 | ||
3924 | /* If final_value != 0, then the biv may be used after loop end | |
3925 | and we must emit an insn to set it just in case. | |
3926 | ||
3927 | Reversed bivs already have an insn after the loop setting their | |
3928 | value, so we don't need another one. We can't calculate the | |
3929 | proper final value for such a biv here anyways. */ | |
3930 | if (final_value != 0 && ! bl->reversed) | |
3931 | { | |
3932 | rtx insert_before; | |
3933 | ||
3934 | /* If the loop has multiple exits, emit the insn before the | |
3935 | loop to ensure that it will always be executed no matter | |
3936 | how the loop exits. Otherwise, emit the insn after the | |
3937 | loop, since this is slightly more efficient. */ | |
3938 | if (loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
3939 | insert_before = loop_start; | |
3940 | else | |
3941 | insert_before = end_insert_before; | |
3942 | ||
3943 | emit_insn_before (gen_move_insn (bl->biv->dest_reg, final_value), | |
3944 | end_insert_before); | |
3945 | } | |
3946 | ||
3947 | #if 0 | |
3948 | /* Delete all of the instructions inside the loop which set | |
3949 | the biv, as they are all dead. If is safe to delete them, | |
3950 | because an insn setting a biv will never be part of a libcall. */ | |
3951 | /* However, deleting them will invalidate the regno_last_uid info, | |
3952 | so keeping them around is more convenient. Final_biv_value | |
3953 | will only succeed when there are multiple exits if the biv | |
3954 | is dead at each exit, hence it does not matter that the original | |
3955 | insn remains, because it is dead anyways. */ | |
3956 | for (v = bl->biv; v; v = v->next_iv) | |
3957 | delete_insn (v->insn); | |
3958 | #endif | |
3959 | ||
3960 | if (loop_dump_stream) | |
3961 | fprintf (loop_dump_stream, "Reg %d: biv eliminated\n", | |
3962 | bl->regno); | |
3963 | } | |
3964 | } | |
3965 | ||
3966 | /* Go through all the instructions in the loop, making all the | |
3967 | register substitutions scheduled in REG_MAP. */ | |
3968 | ||
3969 | for (p = loop_start; p != end; p = NEXT_INSN (p)) | |
3970 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
3971 | || GET_CODE (p) == CALL_INSN) | |
3972 | { | |
3973 | replace_regs (PATTERN (p), reg_map, max_reg_before_loop, 0); | |
3974 | replace_regs (REG_NOTES (p), reg_map, max_reg_before_loop, 0); | |
3975 | INSN_CODE (p) = -1; | |
3976 | } | |
3977 | ||
3978 | /* Unroll loops from within strength reduction so that we can use the | |
3979 | induction variable information that strength_reduce has already | |
3980 | collected. */ | |
3981 | ||
3982 | if (flag_unroll_loops) | |
3983 | unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 1); | |
3984 | ||
3985 | if (loop_dump_stream) | |
3986 | fprintf (loop_dump_stream, "\n"); | |
3987 | } | |
3988 | \f | |
3989 | /* Return 1 if X is a valid source for an initial value (or as value being | |
3990 | compared against in an initial test). | |
3991 | ||
3992 | X must be either a register or constant and must not be clobbered between | |
3993 | the current insn and the start of the loop. | |
3994 | ||
3995 | INSN is the insn containing X. */ | |
3996 | ||
3997 | static int | |
3998 | valid_initial_value_p (x, insn, call_seen, loop_start) | |
3999 | rtx x; | |
4000 | rtx insn; | |
4001 | int call_seen; | |
4002 | rtx loop_start; | |
4003 | { | |
4004 | if (CONSTANT_P (x)) | |
4005 | return 1; | |
4006 | ||
4007 | /* Only consider pseudos we know about initialized in insns whose luids | |
4008 | we know. */ | |
4009 | if (GET_CODE (x) != REG | |
4010 | || REGNO (x) >= max_reg_before_loop) | |
4011 | return 0; | |
4012 | ||
4013 | /* Don't use call-clobbered registers across a call which clobbers it. On | |
4014 | some machines, don't use any hard registers at all. */ | |
4015 | if (REGNO (x) < FIRST_PSEUDO_REGISTER | |
4016 | #ifndef SMALL_REGISTER_CLASSES | |
4017 | && call_used_regs[REGNO (x)] && call_seen | |
4018 | #endif | |
4019 | ) | |
4020 | return 0; | |
4021 | ||
4022 | /* Don't use registers that have been clobbered before the start of the | |
4023 | loop. */ | |
4024 | if (reg_set_between_p (x, insn, loop_start)) | |
4025 | return 0; | |
4026 | ||
4027 | return 1; | |
4028 | } | |
4029 | \f | |
4030 | /* Scan X for memory refs and check each memory address | |
4031 | as a possible giv. INSN is the insn whose pattern X comes from. | |
4032 | NOT_EVERY_ITERATION is 1 if the insn might not be executed during | |
4033 | every loop iteration. */ | |
4034 | ||
4035 | static void | |
4036 | find_mem_givs (x, insn, not_every_iteration, loop_start, loop_end) | |
4037 | rtx x; | |
4038 | rtx insn; | |
4039 | int not_every_iteration; | |
4040 | rtx loop_start, loop_end; | |
4041 | { | |
4042 | register int i, j; | |
4043 | register enum rtx_code code; | |
4044 | register char *fmt; | |
4045 | ||
4046 | if (x == 0) | |
4047 | return; | |
4048 | ||
4049 | code = GET_CODE (x); | |
4050 | switch (code) | |
4051 | { | |
4052 | case REG: | |
4053 | case CONST_INT: | |
4054 | case CONST: | |
4055 | case CONST_DOUBLE: | |
4056 | case SYMBOL_REF: | |
4057 | case LABEL_REF: | |
4058 | case PC: | |
4059 | case CC0: | |
4060 | case ADDR_VEC: | |
4061 | case ADDR_DIFF_VEC: | |
4062 | case USE: | |
4063 | case CLOBBER: | |
4064 | return; | |
4065 | ||
4066 | case MEM: | |
4067 | { | |
4068 | rtx src_reg; | |
4069 | rtx add_val; | |
4070 | rtx mult_val; | |
4071 | int benefit; | |
4072 | ||
4073 | benefit = general_induction_var (XEXP (x, 0), | |
4074 | &src_reg, &add_val, &mult_val); | |
4075 | ||
4076 | /* Don't make a DEST_ADDR giv with mult_val == 1 && add_val == 0. | |
4077 | Such a giv isn't useful. */ | |
4078 | if (benefit > 0 && (mult_val != const1_rtx || add_val != const0_rtx)) | |
4079 | { | |
4080 | /* Found one; record it. */ | |
4081 | struct induction *v | |
4082 | = (struct induction *) oballoc (sizeof (struct induction)); | |
4083 | ||
4084 | record_giv (v, insn, src_reg, addr_placeholder, mult_val, | |
4085 | add_val, benefit, DEST_ADDR, not_every_iteration, | |
4086 | &XEXP (x, 0), loop_start, loop_end); | |
4087 | ||
4088 | v->mem_mode = GET_MODE (x); | |
4089 | } | |
4090 | return; | |
4091 | } | |
4092 | } | |
4093 | ||
4094 | /* Recursively scan the subexpressions for other mem refs. */ | |
4095 | ||
4096 | fmt = GET_RTX_FORMAT (code); | |
4097 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
4098 | if (fmt[i] == 'e') | |
4099 | find_mem_givs (XEXP (x, i), insn, not_every_iteration, loop_start, | |
4100 | loop_end); | |
4101 | else if (fmt[i] == 'E') | |
4102 | for (j = 0; j < XVECLEN (x, i); j++) | |
4103 | find_mem_givs (XVECEXP (x, i, j), insn, not_every_iteration, | |
4104 | loop_start, loop_end); | |
4105 | } | |
4106 | \f | |
4107 | /* Fill in the data about one biv update. | |
4108 | V is the `struct induction' in which we record the biv. (It is | |
4109 | allocated by the caller, with alloca.) | |
4110 | INSN is the insn that sets it. | |
4111 | DEST_REG is the biv's reg. | |
4112 | ||
4113 | MULT_VAL is const1_rtx if the biv is being incremented here, in which case | |
4114 | INC_VAL is the increment. Otherwise, MULT_VAL is const0_rtx and the biv is | |
4115 | being set to INC_VAL. | |
4116 | ||
4117 | NOT_EVERY_ITERATION is nonzero if this biv update is not know to be | |
4118 | executed every iteration; MAYBE_MULTIPLE is nonzero if this biv update | |
4119 | can be executed more than once per iteration. If MAYBE_MULTIPLE | |
4120 | and NOT_EVERY_ITERATION are both zero, we know that the biv update is | |
4121 | executed exactly once per iteration. */ | |
4122 | ||
4123 | static void | |
4124 | record_biv (v, insn, dest_reg, inc_val, mult_val, | |
4125 | not_every_iteration, maybe_multiple) | |
4126 | struct induction *v; | |
4127 | rtx insn; | |
4128 | rtx dest_reg; | |
4129 | rtx inc_val; | |
4130 | rtx mult_val; | |
4131 | int not_every_iteration; | |
4132 | int maybe_multiple; | |
4133 | { | |
4134 | struct iv_class *bl; | |
4135 | ||
4136 | v->insn = insn; | |
4137 | v->src_reg = dest_reg; | |
4138 | v->dest_reg = dest_reg; | |
4139 | v->mult_val = mult_val; | |
4140 | v->add_val = inc_val; | |
4141 | v->mode = GET_MODE (dest_reg); | |
4142 | v->always_computable = ! not_every_iteration; | |
4143 | v->maybe_multiple = maybe_multiple; | |
4144 | ||
4145 | /* Add this to the reg's iv_class, creating a class | |
4146 | if this is the first incrementation of the reg. */ | |
4147 | ||
4148 | bl = reg_biv_class[REGNO (dest_reg)]; | |
4149 | if (bl == 0) | |
4150 | { | |
4151 | /* Create and initialize new iv_class. */ | |
4152 | ||
4153 | bl = (struct iv_class *) oballoc (sizeof (struct iv_class)); | |
4154 | ||
4155 | bl->regno = REGNO (dest_reg); | |
4156 | bl->biv = 0; | |
4157 | bl->giv = 0; | |
4158 | bl->biv_count = 0; | |
4159 | bl->giv_count = 0; | |
4160 | ||
4161 | /* Set initial value to the reg itself. */ | |
4162 | bl->initial_value = dest_reg; | |
4163 | /* We haven't seen the initializing insn yet */ | |
4164 | bl->init_insn = 0; | |
4165 | bl->init_set = 0; | |
4166 | bl->initial_test = 0; | |
4167 | bl->incremented = 0; | |
4168 | bl->eliminable = 0; | |
4169 | bl->nonneg = 0; | |
4170 | bl->reversed = 0; | |
4171 | bl->total_benefit = 0; | |
4172 | ||
4173 | /* Add this class to loop_iv_list. */ | |
4174 | bl->next = loop_iv_list; | |
4175 | loop_iv_list = bl; | |
4176 | ||
4177 | /* Put it in the array of biv register classes. */ | |
4178 | reg_biv_class[REGNO (dest_reg)] = bl; | |
4179 | } | |
4180 | ||
4181 | /* Update IV_CLASS entry for this biv. */ | |
4182 | v->next_iv = bl->biv; | |
4183 | bl->biv = v; | |
4184 | bl->biv_count++; | |
4185 | if (mult_val == const1_rtx) | |
4186 | bl->incremented = 1; | |
4187 | ||
4188 | if (loop_dump_stream) | |
4189 | { | |
4190 | fprintf (loop_dump_stream, | |
4191 | "Insn %d: possible biv, reg %d,", | |
4192 | INSN_UID (insn), REGNO (dest_reg)); | |
4193 | if (GET_CODE (inc_val) == CONST_INT) | |
4194 | fprintf (loop_dump_stream, " const = %d\n", | |
4195 | INTVAL (inc_val)); | |
4196 | else | |
4197 | { | |
4198 | fprintf (loop_dump_stream, " const = "); | |
4199 | print_rtl (loop_dump_stream, inc_val); | |
4200 | fprintf (loop_dump_stream, "\n"); | |
4201 | } | |
4202 | } | |
4203 | } | |
4204 | \f | |
4205 | /* Fill in the data about one giv. | |
4206 | V is the `struct induction' in which we record the giv. (It is | |
4207 | allocated by the caller, with alloca.) | |
4208 | INSN is the insn that sets it. | |
4209 | BENEFIT estimates the savings from deleting this insn. | |
4210 | TYPE is DEST_REG or DEST_ADDR; it says whether the giv is computed | |
4211 | into a register or is used as a memory address. | |
4212 | ||
4213 | SRC_REG is the biv reg which the giv is computed from. | |
4214 | DEST_REG is the giv's reg (if the giv is stored in a reg). | |
4215 | MULT_VAL and ADD_VAL are the coefficients used to compute the giv. | |
4216 | LOCATION points to the place where this giv's value appears in INSN. */ | |
4217 | ||
4218 | static void | |
4219 | record_giv (v, insn, src_reg, dest_reg, mult_val, add_val, benefit, | |
4220 | type, not_every_iteration, location, loop_start, loop_end) | |
4221 | struct induction *v; | |
4222 | rtx insn; | |
4223 | rtx src_reg; | |
4224 | rtx dest_reg; | |
4225 | rtx mult_val, add_val; | |
4226 | int benefit; | |
4227 | enum g_types type; | |
4228 | int not_every_iteration; | |
4229 | rtx *location; | |
4230 | rtx loop_start, loop_end; | |
4231 | { | |
4232 | struct induction *b; | |
4233 | struct iv_class *bl; | |
4234 | rtx set = single_set (insn); | |
4235 | rtx p; | |
4236 | ||
4237 | v->insn = insn; | |
4238 | v->src_reg = src_reg; | |
4239 | v->giv_type = type; | |
4240 | v->dest_reg = dest_reg; | |
4241 | v->mult_val = mult_val; | |
4242 | v->add_val = add_val; | |
4243 | v->benefit = benefit; | |
4244 | v->location = location; | |
4245 | v->cant_derive = 0; | |
4246 | v->combined_with = 0; | |
4247 | v->maybe_multiple = 0; | |
4248 | v->maybe_dead = 0; | |
4249 | v->derive_adjustment = 0; | |
4250 | v->same = 0; | |
4251 | v->ignore = 0; | |
4252 | v->new_reg = 0; | |
4253 | v->final_value = 0; | |
4254 | ||
4255 | /* The v->always_computable field is used in update_giv_derive, to | |
4256 | determine whether a giv can be used to derive another giv. For a | |
4257 | DEST_REG giv, INSN computes a new value for the giv, so its value | |
4258 | isn't computable if INSN insn't executed every iteration. | |
4259 | However, for a DEST_ADDR giv, INSN merely uses the value of the giv; | |
4260 | it does not compute a new value. Hence the value is always computable | |
4261 | regardless of whether INSN is executed each iteration. */ | |
4262 | ||
4263 | if (type == DEST_ADDR) | |
4264 | v->always_computable = 1; | |
4265 | else | |
4266 | v->always_computable = ! not_every_iteration; | |
4267 | ||
4268 | if (type == DEST_ADDR) | |
4269 | { | |
4270 | v->mode = GET_MODE (*location); | |
4271 | v->lifetime = 1; | |
4272 | v->times_used = 1; | |
4273 | } | |
4274 | else /* type == DEST_REG */ | |
4275 | { | |
4276 | v->mode = GET_MODE (SET_DEST (set)); | |
4277 | ||
4278 | v->lifetime = (uid_luid[regno_last_uid[REGNO (dest_reg)]] | |
4279 | - uid_luid[regno_first_uid[REGNO (dest_reg)]]); | |
4280 | ||
4281 | v->times_used = n_times_used[REGNO (dest_reg)]; | |
4282 | ||
4283 | /* If the lifetime is zero, it means that this register is | |
4284 | really a dead store. So mark this as a giv that can be | |
4285 | ignored. This will not prevent the biv from being eliminated. */ | |
4286 | if (v->lifetime == 0) | |
4287 | v->ignore = 1; | |
4288 | ||
4289 | reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT; | |
4290 | reg_iv_info[REGNO (dest_reg)] = v; | |
4291 | } | |
4292 | ||
4293 | /* Add the giv to the class of givs computed from one biv. */ | |
4294 | ||
4295 | bl = reg_biv_class[REGNO (src_reg)]; | |
4296 | if (bl) | |
4297 | { | |
4298 | v->next_iv = bl->giv; | |
4299 | bl->giv = v; | |
4300 | /* Don't count DEST_ADDR. This is supposed to count the number of | |
4301 | insns that calculate givs. */ | |
4302 | if (type == DEST_REG) | |
4303 | bl->giv_count++; | |
4304 | bl->total_benefit += benefit; | |
4305 | } | |
4306 | else | |
4307 | /* Fatal error, biv missing for this giv? */ | |
4308 | abort (); | |
4309 | ||
4310 | if (type == DEST_ADDR) | |
4311 | v->replaceable = 1; | |
4312 | else | |
4313 | { | |
4314 | /* The giv can be replaced outright by the reduced register only if all | |
4315 | of the following conditions are true: | |
4316 | - the insn that sets the giv is always executed on any iteration | |
4317 | on which the giv is used at all | |
4318 | (there are two ways to deduce this: | |
4319 | either the insn is executed on every iteration, | |
4320 | or all uses follow that insn in the same basic block), | |
4321 | - the giv is not used outside the loop | |
4322 | - no assignments to the biv occur during the giv's lifetime. */ | |
4323 | ||
4324 | if (regno_first_uid[REGNO (dest_reg)] == INSN_UID (insn) | |
4325 | /* Previous line always fails if INSN was moved by loop opt. */ | |
4326 | && uid_luid[regno_last_uid[REGNO (dest_reg)]] < INSN_LUID (loop_end) | |
4327 | && (! not_every_iteration | |
4328 | || last_use_this_basic_block (dest_reg, insn))) | |
4329 | { | |
4330 | /* Now check that there are no assignments to the biv within the | |
4331 | giv's lifetime. This requires two separate checks. */ | |
4332 | ||
4333 | /* Check each biv update, and fail if any are between the first | |
4334 | and last use of the giv. | |
4335 | ||
4336 | If this loop contains an inner loop that was unrolled, then | |
4337 | the insn modifying the biv may have been emitted by the loop | |
4338 | unrolling code, and hence does not have a valid luid. Just | |
4339 | mark the biv as not replaceable in this case. It is not very | |
4340 | useful as a biv, because it is used in two different loops. | |
4341 | It is very unlikely that we would be able to optimize the giv | |
4342 | using this biv anyways. */ | |
4343 | ||
4344 | v->replaceable = 1; | |
4345 | for (b = bl->biv; b; b = b->next_iv) | |
4346 | { | |
4347 | if (INSN_UID (b->insn) >= max_uid_for_loop | |
4348 | || ((uid_luid[INSN_UID (b->insn)] | |
4349 | >= uid_luid[regno_first_uid[REGNO (dest_reg)]]) | |
4350 | && (uid_luid[INSN_UID (b->insn)] | |
4351 | <= uid_luid[regno_last_uid[REGNO (dest_reg)]]))) | |
4352 | { | |
4353 | v->replaceable = 0; | |
4354 | v->not_replaceable = 1; | |
4355 | break; | |
4356 | } | |
4357 | } | |
4358 | ||
4359 | /* Check each insn between the first and last use of the giv, | |
4360 | and fail if any of them are branches that jump to a named label | |
4361 | outside this range, but still inside the loop. This catches | |
4362 | cases of spaghetti code where the execution order of insns | |
4363 | is not linear, and hence the above test fails. For example, | |
4364 | in the following code, j is not replaceable: | |
4365 | for (i = 0; i < 100; ) { | |
4366 | L0: j = 4*i; goto L1; | |
4367 | L2: k = j; goto L3; | |
4368 | L1: i++; goto L2; | |
4369 | L3: ; } | |
4370 | printf ("k = %d\n", k); } | |
4371 | This test is conservative, but this test succeeds rarely enough | |
4372 | that it isn't a problem. See also check_final_value below. */ | |
4373 | ||
4374 | if (v->replaceable) | |
4375 | for (p = insn; | |
4376 | INSN_UID (p) >= max_uid_for_loop | |
4377 | || INSN_LUID (p) < uid_luid[regno_last_uid[REGNO (dest_reg)]]; | |
4378 | p = NEXT_INSN (p)) | |
4379 | { | |
4380 | if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) | |
4381 | && LABEL_NAME (JUMP_LABEL (p)) | |
4382 | && ((INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start) | |
4383 | && (INSN_LUID (JUMP_LABEL (p)) | |
4384 | < uid_luid[regno_first_uid[REGNO (dest_reg)]])) | |
4385 | || (INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end) | |
4386 | && (INSN_LUID (JUMP_LABEL (p)) | |
4387 | > uid_luid[regno_last_uid[REGNO (dest_reg)]])))) | |
4388 | { | |
4389 | v->replaceable = 0; | |
4390 | v->not_replaceable = 1; | |
4391 | ||
4392 | if (loop_dump_stream) | |
4393 | fprintf (loop_dump_stream, | |
4394 | "Found branch outside giv lifetime.\n"); | |
4395 | ||
4396 | break; | |
4397 | } | |
4398 | } | |
4399 | } | |
4400 | else | |
4401 | { | |
4402 | /* May still be replaceable, we don't have enough info here to | |
4403 | decide. */ | |
4404 | v->replaceable = 0; | |
4405 | v->not_replaceable = 0; | |
4406 | } | |
4407 | } | |
4408 | ||
4409 | if (loop_dump_stream) | |
4410 | { | |
4411 | if (type == DEST_REG) | |
4412 | fprintf (loop_dump_stream, "Insn %d: giv reg %d", | |
4413 | INSN_UID (insn), REGNO (dest_reg)); | |
4414 | else | |
4415 | fprintf (loop_dump_stream, "Insn %d: dest address", | |
4416 | INSN_UID (insn)); | |
4417 | ||
4418 | fprintf (loop_dump_stream, " src reg %d benefit %d", | |
4419 | REGNO (src_reg), v->benefit); | |
4420 | fprintf (loop_dump_stream, " used %d lifetime %d", | |
4421 | v->times_used, v->lifetime); | |
4422 | ||
4423 | if (v->replaceable) | |
4424 | fprintf (loop_dump_stream, " replaceable"); | |
4425 | ||
4426 | if (GET_CODE (mult_val) == CONST_INT) | |
4427 | fprintf (loop_dump_stream, " mult %d", | |
4428 | INTVAL (mult_val)); | |
4429 | else | |
4430 | { | |
4431 | fprintf (loop_dump_stream, " mult "); | |
4432 | print_rtl (loop_dump_stream, mult_val); | |
4433 | } | |
4434 | ||
4435 | if (GET_CODE (add_val) == CONST_INT) | |
4436 | fprintf (loop_dump_stream, " add %d", | |
4437 | INTVAL (add_val)); | |
4438 | else | |
4439 | { | |
4440 | fprintf (loop_dump_stream, " add "); | |
4441 | print_rtl (loop_dump_stream, add_val); | |
4442 | } | |
4443 | } | |
4444 | ||
4445 | if (loop_dump_stream) | |
4446 | fprintf (loop_dump_stream, "\n"); | |
4447 | ||
4448 | } | |
4449 | ||
4450 | ||
4451 | /* All this does is determine whether a giv can be made replaceable because | |
4452 | its final value can be calculated. This code can not be part of record_giv | |
4453 | above, because final_giv_value requires that the number of loop iterations | |
4454 | be known, and that can not be accurately calculated until after all givs | |
4455 | have been identified. */ | |
4456 | ||
4457 | static void | |
4458 | check_final_value (v, loop_start, loop_end) | |
4459 | struct induction *v; | |
4460 | rtx loop_start, loop_end; | |
4461 | { | |
4462 | struct iv_class *bl; | |
4463 | rtx final_value = 0; | |
4464 | rtx tem; | |
4465 | ||
4466 | bl = reg_biv_class[REGNO (v->src_reg)]; | |
4467 | ||
4468 | /* DEST_ADDR givs will never reach here, because they are always marked | |
4469 | replaceable above in record_giv. */ | |
4470 | ||
4471 | /* The giv can be replaced outright by the reduced register only if all | |
4472 | of the following conditions are true: | |
4473 | - the insn that sets the giv is always executed on any iteration | |
4474 | on which the giv is used at all | |
4475 | (there are two ways to deduce this: | |
4476 | either the insn is executed on every iteration, | |
4477 | or all uses follow that insn in the same basic block), | |
4478 | - its final value can be calculated (this condition is different | |
4479 | than the one above in record_giv) | |
4480 | - no assignments to the biv occur during the giv's lifetime. */ | |
4481 | ||
4482 | #if 0 | |
4483 | /* This is only called now when replaceable is known to be false. */ | |
4484 | /* Clear replaceable, so that it won't confuse final_giv_value. */ | |
4485 | v->replaceable = 0; | |
4486 | #endif | |
4487 | ||
4488 | if ((final_value = final_giv_value (v, loop_start, loop_end)) | |
4489 | && (v->always_computable || last_use_this_basic_block (v->dest_reg, v->insn))) | |
4490 | { | |
4491 | int biv_increment_seen = 0; | |
4492 | rtx p = v->insn; | |
4493 | rtx last_giv_use; | |
4494 | ||
4495 | v->replaceable = 1; | |
4496 | ||
4497 | /* When trying to determine whether or not a biv increment occurs | |
4498 | during the lifetime of the giv, we can ignore uses of the variable | |
4499 | outside the loop because final_value is true. Hence we can not | |
4500 | use regno_last_uid and regno_first_uid as above in record_giv. */ | |
4501 | ||
4502 | /* Search the loop to determine whether any assignments to the | |
4503 | biv occur during the giv's lifetime. Start with the insn | |
4504 | that sets the giv, and search around the loop until we come | |
4505 | back to that insn again. | |
4506 | ||
4507 | Also fail if there is a jump within the giv's lifetime that jumps | |
4508 | to somewhere outside the lifetime but still within the loop. This | |
4509 | catches spaghetti code where the execution order is not linear, and | |
4510 | hence the above test fails. Here we assume that the giv lifetime | |
4511 | does not extend from one iteration of the loop to the next, so as | |
4512 | to make the test easier. Since the lifetime isn't known yet, | |
4513 | this requires two loops. See also record_giv above. */ | |
4514 | ||
4515 | last_giv_use = v->insn; | |
4516 | ||
4517 | while (1) | |
4518 | { | |
4519 | p = NEXT_INSN (p); | |
4520 | if (p == loop_end) | |
4521 | p = NEXT_INSN (loop_start); | |
4522 | if (p == v->insn) | |
4523 | break; | |
4524 | ||
4525 | if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN | |
4526 | || GET_CODE (p) == CALL_INSN) | |
4527 | { | |
4528 | if (biv_increment_seen) | |
4529 | { | |
4530 | if (reg_mentioned_p (v->dest_reg, PATTERN (p))) | |
4531 | { | |
4532 | v->replaceable = 0; | |
4533 | v->not_replaceable = 1; | |
4534 | break; | |
4535 | } | |
4536 | } | |
4537 | else if (GET_CODE (PATTERN (p)) == SET | |
4538 | && SET_DEST (PATTERN (p)) == v->src_reg) | |
4539 | biv_increment_seen = 1; | |
4540 | else if (reg_mentioned_p (v->dest_reg, PATTERN (p))) | |
4541 | last_giv_use = p; | |
4542 | } | |
4543 | } | |
4544 | ||
4545 | /* Now that the lifetime of the giv is known, check for branches | |
4546 | from within the lifetime to outside the lifetime if it is still | |
4547 | replaceable. */ | |
4548 | ||
4549 | if (v->replaceable) | |
4550 | { | |
4551 | p = v->insn; | |
4552 | while (1) | |
4553 | { | |
4554 | p = NEXT_INSN (p); | |
4555 | if (p == loop_end) | |
4556 | p = NEXT_INSN (loop_start); | |
4557 | if (p == last_giv_use) | |
4558 | break; | |
4559 | ||
4560 | if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) | |
4561 | && LABEL_NAME (JUMP_LABEL (p)) | |
4562 | && ((INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (v->insn) | |
4563 | && INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start)) | |
4564 | || (INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (last_giv_use) | |
4565 | && INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end)))) | |
4566 | { | |
4567 | v->replaceable = 0; | |
4568 | v->not_replaceable = 1; | |
4569 | ||
4570 | if (loop_dump_stream) | |
4571 | fprintf (loop_dump_stream, | |
4572 | "Found branch outside giv lifetime.\n"); | |
4573 | ||
4574 | break; | |
4575 | } | |
4576 | } | |
4577 | } | |
4578 | ||
4579 | /* If it is replaceable, then save the final value. */ | |
4580 | if (v->replaceable) | |
4581 | v->final_value = final_value; | |
4582 | } | |
4583 | ||
4584 | if (loop_dump_stream && v->replaceable) | |
4585 | fprintf (loop_dump_stream, "Insn %d: giv reg %d final_value replaceable\n", | |
4586 | INSN_UID (v->insn), REGNO (v->dest_reg)); | |
4587 | } | |
4588 | \f | |
4589 | /* Update the status of whether a giv can derive other givs. | |
4590 | ||
4591 | We need to do something special if there is or may be an update to the biv | |
4592 | between the time the giv is defined and the time it is used to derive | |
4593 | another giv. | |
4594 | ||
4595 | In addition, a giv that is only conditionally set is not allowed to | |
4596 | derive another giv once a label has been passed. | |
4597 | ||
4598 | The cases we look at are when a label or an update to a biv is passed. */ | |
4599 | ||
4600 | static void | |
4601 | update_giv_derive (p) | |
4602 | rtx p; | |
4603 | { | |
4604 | struct iv_class *bl; | |
4605 | struct induction *biv, *giv; | |
4606 | rtx tem; | |
4607 | int dummy; | |
4608 | ||
4609 | /* Search all IV classes, then all bivs, and finally all givs. | |
4610 | ||
4611 | There are three cases we are concerned with. First we have the situation | |
4612 | of a giv that is only updated conditionally. In that case, it may not | |
4613 | derive any givs after a label is passed. | |
4614 | ||
4615 | The second case is when a biv update occurs, or may occur, after the | |
4616 | definition of a giv. For certain biv updates (see below) that are | |
4617 | known to occur between the giv definition and use, we can adjust the | |
4618 | giv definition. For others, or when the biv update is conditional, | |
4619 | we must prevent the giv from deriving any other givs. There are two | |
4620 | sub-cases within this case. | |
4621 | ||
4622 | If this is a label, we are concerned with any biv update that is done | |
4623 | conditionally, since it may be done after the giv is defined followed by | |
4624 | a branch here (actually, we need to pass both a jump and a label, but | |
4625 | this extra tracking doesn't seem worth it). | |
4626 | ||
4627 | If this is a jump, we are concerned about any biv update that may be | |
4628 | executed multiple times. We are actually only concerned about | |
4629 | backward jumps, but it is probably not worth performing the test | |
4630 | on the jump again here. | |
4631 | ||
4632 | If this is a biv update, we must adjust the giv status to show that a | |
4633 | subsequent biv update was performed. If this adjustment cannot be done, | |
4634 | the giv cannot derive further givs. */ | |
4635 | ||
4636 | for (bl = loop_iv_list; bl; bl = bl->next) | |
4637 | for (biv = bl->biv; biv; biv = biv->next_iv) | |
4638 | if (GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN | |
4639 | || biv->insn == p) | |
4640 | { | |
4641 | for (giv = bl->giv; giv; giv = giv->next_iv) | |
4642 | { | |
4643 | /* If cant_derive is already true, there is no point in | |
4644 | checking all of these conditions again. */ | |
4645 | if (giv->cant_derive) | |
4646 | continue; | |
4647 | ||
4648 | /* If this giv is conditionally set and we have passed a label, | |
4649 | it cannot derive anything. */ | |
4650 | if (GET_CODE (p) == CODE_LABEL && ! giv->always_computable) | |
4651 | giv->cant_derive = 1; | |
4652 | ||
4653 | /* Skip givs that have mult_val == 0, since | |
4654 | they are really invariants. Also skip those that are | |
4655 | replaceable, since we know their lifetime doesn't contain | |
4656 | any biv update. */ | |
4657 | else if (giv->mult_val == const0_rtx || giv->replaceable) | |
4658 | continue; | |
4659 | ||
4660 | /* The only way we can allow this giv to derive another | |
4661 | is if this is a biv increment and we can form the product | |
4662 | of biv->add_val and giv->mult_val. In this case, we will | |
4663 | be able to compute a compensation. */ | |
4664 | else if (biv->insn == p) | |
4665 | { | |
4666 | tem = 0; | |
4667 | ||
4668 | if (biv->mult_val == const1_rtx) | |
4669 | tem = simplify_giv_expr (gen_rtx (MULT, giv->mode, | |
4670 | biv->add_val, | |
4671 | giv->mult_val), | |
4672 | &dummy); | |
4673 | ||
4674 | if (tem && giv->derive_adjustment) | |
4675 | tem = simplify_giv_expr (gen_rtx (PLUS, giv->mode, tem, | |
4676 | giv->derive_adjustment), | |
4677 | &dummy); | |
4678 | if (tem) | |
4679 | giv->derive_adjustment = tem; | |
4680 | else | |
4681 | giv->cant_derive = 1; | |
4682 | } | |
4683 | else if ((GET_CODE (p) == CODE_LABEL && ! biv->always_computable) | |
4684 | || (GET_CODE (p) == JUMP_INSN && biv->maybe_multiple)) | |
4685 | giv->cant_derive = 1; | |
4686 | } | |
4687 | } | |
4688 | } | |
4689 | \f | |
4690 | /* Check whether an insn is an increment legitimate for a basic induction var. | |
4691 | X is the source of insn P. | |
4692 | DEST_REG is the putative biv, also the destination of the insn. | |
4693 | We accept patterns of these forms: | |
4694 | REG = REG + INVARIANT (includes REG = REG - CONSTANT) | |
4695 | REG = INVARIANT + REG | |
4696 | ||
4697 | If X is suitable, we return 1, set *MULT_VAL to CONST1_RTX, | |
4698 | and store the additive term into *INC_VAL. | |
4699 | ||
4700 | If X is an assignment of an invariant into DEST_REG, we set | |
4701 | *MULT_VAL to CONST0_RTX, and store the invariant into *INC_VAL. | |
4702 | ||
4703 | We also want to detect a BIV when it corresponds to a variable | |
4704 | whose mode was promoted via PROMOTED_MODE. In that case, an increment | |
4705 | of the variable may be a PLUS that adds a SUBREG of that variable to | |
4706 | an invariant and then sign- or zero-extends the result of the PLUS | |
4707 | into the variable. | |
4708 | ||
4709 | Most GIVs in such cases will be in the promoted mode, since that is the | |
4710 | probably the natural computation mode (and almost certainly the mode | |
4711 | used for addresses) on the machine. So we view the pseudo-reg containing | |
4712 | the variable as the BIV, as if it were simply incremented. | |
4713 | ||
4714 | Note that treating the entire pseudo as a BIV will result in making | |
4715 | simple increments to any GIVs based on it. However, if the variable | |
4716 | overflows in its declared mode but not its promoted mode, the result will | |
4717 | be incorrect. This is acceptable if the variable is signed, since | |
4718 | overflows in such cases are undefined, but not if it is unsigned, since | |
4719 | those overflows are defined. So we only check for SIGN_EXTEND and | |
4720 | not ZERO_EXTEND. | |
4721 | ||
4722 | If we cannot find a biv, we return 0. */ | |
4723 | ||
4724 | static int | |
4725 | basic_induction_var (x, dest_reg, p, inc_val, mult_val) | |
4726 | register rtx x; | |
4727 | rtx p; | |
4728 | rtx dest_reg; | |
4729 | rtx *inc_val; | |
4730 | rtx *mult_val; | |
4731 | { | |
4732 | register enum rtx_code code; | |
4733 | rtx arg; | |
4734 | rtx insn, set = 0; | |
4735 | ||
4736 | code = GET_CODE (x); | |
4737 | switch (code) | |
4738 | { | |
4739 | case PLUS: | |
4740 | if (XEXP (x, 0) == dest_reg | |
4741 | || (GET_CODE (XEXP (x, 0)) == SUBREG | |
4742 | && SUBREG_PROMOTED_VAR_P (XEXP (x, 0)) | |
4743 | && SUBREG_REG (XEXP (x, 0)) == dest_reg)) | |
4744 | arg = XEXP (x, 1); | |
4745 | else if (XEXP (x, 1) == dest_reg | |
4746 | || (GET_CODE (XEXP (x, 1)) == SUBREG | |
4747 | && SUBREG_PROMOTED_VAR_P (XEXP (x, 1)) | |
4748 | && SUBREG_REG (XEXP (x, 1)) == dest_reg)) | |
4749 | arg = XEXP (x, 0); | |
4750 | else | |
4751 | return 0; | |
4752 | ||
4753 | if (invariant_p (arg) != 1) | |
4754 | return 0; | |
4755 | ||
4756 | *inc_val = convert_to_mode (GET_MODE (dest_reg), arg, 0);; | |
4757 | *mult_val = const1_rtx; | |
4758 | return 1; | |
4759 | ||
4760 | case SUBREG: | |
4761 | /* If this is a SUBREG for a promoted variable, check the inner | |
4762 | value. */ | |
4763 | if (SUBREG_PROMOTED_VAR_P (x)) | |
4764 | return basic_induction_var (SUBREG_REG (x), dest_reg, p, | |
4765 | inc_val, mult_val); | |
4766 | ||
4767 | case REG: | |
4768 | /* If this register is assigned in the previous insn, look at its | |
4769 | source, but don't go outside the loop or past a label. */ | |
4770 | ||
4771 | for (insn = PREV_INSN (p); | |
4772 | (insn && GET_CODE (insn) == NOTE | |
4773 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG); | |
4774 | insn = PREV_INSN (insn)) | |
4775 | ; | |
4776 | ||
4777 | if (insn) | |
4778 | set = single_set (insn); | |
4779 | ||
4780 | if (set != 0 && SET_DEST (set) == x) | |
4781 | return basic_induction_var (SET_SRC (set), dest_reg, insn, | |
4782 | inc_val, mult_val); | |
4783 | /* ... fall through ... */ | |
4784 | ||
4785 | /* Can accept constant setting of biv only when inside inner most loop. | |
4786 | Otherwise, a biv of an inner loop may be incorrectly recognized | |
4787 | as a biv of the outer loop, | |
4788 | causing code to be moved INTO the inner loop. */ | |
4789 | case MEM: | |
4790 | if (invariant_p (x) != 1) | |
4791 | return 0; | |
4792 | case CONST_INT: | |
4793 | case SYMBOL_REF: | |
4794 | case CONST: | |
4795 | if (loops_enclosed == 1) | |
4796 | { | |
4797 | *inc_val = convert_to_mode (GET_MODE (dest_reg), x, 0);; | |
4798 | *mult_val = const0_rtx; | |
4799 | return 1; | |
4800 | } | |
4801 | else | |
4802 | return 0; | |
4803 | ||
4804 | case SIGN_EXTEND: | |
4805 | return basic_induction_var (XEXP (x, 0), dest_reg, p, | |
4806 | inc_val, mult_val); | |
4807 | case ASHIFTRT: | |
4808 | /* Similar, since this can be a sign extension. */ | |
4809 | for (insn = PREV_INSN (p); | |
4810 | (insn && GET_CODE (insn) == NOTE | |
4811 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG); | |
4812 | insn = PREV_INSN (insn)) | |
4813 | ; | |
4814 | ||
4815 | if (insn) | |
4816 | set = single_set (insn); | |
4817 | ||
4818 | if (set && SET_DEST (set) == XEXP (x, 0) | |
4819 | && GET_CODE (XEXP (x, 1)) == CONST_INT | |
4820 | && INTVAL (XEXP (x, 1)) >= 0 | |
4821 | && GET_CODE (SET_SRC (set)) == ASHIFT | |
4822 | && XEXP (x, 1) == XEXP (SET_SRC (set), 1)) | |
4823 | return basic_induction_var (XEXP (SET_SRC (set), 0), dest_reg, insn, | |
4824 | inc_val, mult_val); | |
4825 | return 0; | |
4826 | ||
4827 | default: | |
4828 | return 0; | |
4829 | } | |
4830 | } | |
4831 | \f | |
4832 | /* A general induction variable (giv) is any quantity that is a linear | |
4833 | function of a basic induction variable, | |
4834 | i.e. giv = biv * mult_val + add_val. | |
4835 | The coefficients can be any loop invariant quantity. | |
4836 | A giv need not be computed directly from the biv; | |
4837 | it can be computed by way of other givs. */ | |
4838 | ||
4839 | /* Determine whether X computes a giv. | |
4840 | If it does, return a nonzero value | |
4841 | which is the benefit from eliminating the computation of X; | |
4842 | set *SRC_REG to the register of the biv that it is computed from; | |
4843 | set *ADD_VAL and *MULT_VAL to the coefficients, | |
4844 | such that the value of X is biv * mult + add; */ | |
4845 | ||
4846 | static int | |
4847 | general_induction_var (x, src_reg, add_val, mult_val) | |
4848 | rtx x; | |
4849 | rtx *src_reg; | |
4850 | rtx *add_val; | |
4851 | rtx *mult_val; | |
4852 | { | |
4853 | rtx orig_x = x; | |
4854 | int benefit = 0; | |
4855 | char *storage; | |
4856 | ||
4857 | /* If this is an invariant, forget it, it isn't a giv. */ | |
4858 | if (invariant_p (x) == 1) | |
4859 | return 0; | |
4860 | ||
4861 | /* See if the expression could be a giv and get its form. | |
4862 | Mark our place on the obstack in case we don't find a giv. */ | |
4863 | storage = (char *) oballoc (0); | |
4864 | x = simplify_giv_expr (x, &benefit); | |
4865 | if (x == 0) | |
4866 | { | |
4867 | obfree (storage); | |
4868 | return 0; | |
4869 | } | |
4870 | ||
4871 | switch (GET_CODE (x)) | |
4872 | { | |
4873 | case USE: | |
4874 | case CONST_INT: | |
4875 | /* Since this is now an invariant and wasn't before, it must be a giv | |
4876 | with MULT_VAL == 0. It doesn't matter which BIV we associate this | |
4877 | with. */ | |
4878 | *src_reg = loop_iv_list->biv->dest_reg; | |
4879 | *mult_val = const0_rtx; | |
4880 | *add_val = x; | |
4881 | break; | |
4882 | ||
4883 | case REG: | |
4884 | /* This is equivalent to a BIV. */ | |
4885 | *src_reg = x; | |
4886 | *mult_val = const1_rtx; | |
4887 | *add_val = const0_rtx; | |
4888 | break; | |
4889 | ||
4890 | case PLUS: | |
4891 | /* Either (plus (biv) (invar)) or | |
4892 | (plus (mult (biv) (invar_1)) (invar_2)). */ | |
4893 | if (GET_CODE (XEXP (x, 0)) == MULT) | |
4894 | { | |
4895 | *src_reg = XEXP (XEXP (x, 0), 0); | |
4896 | *mult_val = XEXP (XEXP (x, 0), 1); | |
4897 | } | |
4898 | else | |
4899 | { | |
4900 | *src_reg = XEXP (x, 0); | |
4901 | *mult_val = const1_rtx; | |
4902 | } | |
4903 | *add_val = XEXP (x, 1); | |
4904 | break; | |
4905 | ||
4906 | case MULT: | |
4907 | /* ADD_VAL is zero. */ | |
4908 | *src_reg = XEXP (x, 0); | |
4909 | *mult_val = XEXP (x, 1); | |
4910 | *add_val = const0_rtx; | |
4911 | break; | |
4912 | ||
4913 | default: | |
4914 | abort (); | |
4915 | } | |
4916 | ||
4917 | /* Remove any enclosing USE from ADD_VAL and MULT_VAL (there will be | |
4918 | unless they are CONST_INT). */ | |
4919 | if (GET_CODE (*add_val) == USE) | |
4920 | *add_val = XEXP (*add_val, 0); | |
4921 | if (GET_CODE (*mult_val) == USE) | |
4922 | *mult_val = XEXP (*mult_val, 0); | |
4923 | ||
4924 | benefit += rtx_cost (orig_x, SET); | |
4925 | ||
4926 | /* Always return some benefit if this is a giv so it will be detected | |
4927 | as such. This allows elimination of bivs that might otherwise | |
4928 | not be eliminated. */ | |
4929 | return benefit == 0 ? 1 : benefit; | |
4930 | } | |
4931 | \f | |
4932 | /* Given an expression, X, try to form it as a linear function of a biv. | |
4933 | We will canonicalize it to be of the form | |
4934 | (plus (mult (BIV) (invar_1)) | |
4935 | (invar_2)) | |
4936 | with possible degeneracies. | |
4937 | ||
4938 | The invariant expressions must each be of a form that can be used as a | |
4939 | machine operand. We surround then with a USE rtx (a hack, but localized | |
4940 | and certainly unambiguous!) if not a CONST_INT for simplicity in this | |
4941 | routine; it is the caller's responsibility to strip them. | |
4942 | ||
4943 | If no such canonicalization is possible (i.e., two biv's are used or an | |
4944 | expression that is neither invariant nor a biv or giv), this routine | |
4945 | returns 0. | |
4946 | ||
4947 | For a non-zero return, the result will have a code of CONST_INT, USE, | |
4948 | REG (for a BIV), PLUS, or MULT. No other codes will occur. | |
4949 | ||
4950 | *BENEFIT will be incremented by the benefit of any sub-giv encountered. */ | |
4951 | ||
4952 | static rtx | |
4953 | simplify_giv_expr (x, benefit) | |
4954 | rtx x; | |
4955 | int *benefit; | |
4956 | { | |
4957 | enum machine_mode mode = GET_MODE (x); | |
4958 | rtx arg0, arg1; | |
4959 | rtx tem; | |
4960 | ||
4961 | /* If this is not an integer mode, or if we cannot do arithmetic in this | |
4962 | mode, this can't be a giv. */ | |
4963 | if (mode != VOIDmode | |
4964 | && (GET_MODE_CLASS (mode) != MODE_INT | |
4965 | || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT)) | |
4966 | return 0; | |
4967 | ||
4968 | switch (GET_CODE (x)) | |
4969 | { | |
4970 | case PLUS: | |
4971 | arg0 = simplify_giv_expr (XEXP (x, 0), benefit); | |
4972 | arg1 = simplify_giv_expr (XEXP (x, 1), benefit); | |
4973 | if (arg0 == 0 || arg1 == 0) | |
4974 | return 0; | |
4975 | ||
4976 | /* Put constant last, CONST_INT last if both constant. */ | |
4977 | if ((GET_CODE (arg0) == USE | |
4978 | || GET_CODE (arg0) == CONST_INT) | |
4979 | && GET_CODE (arg1) != CONST_INT) | |
4980 | tem = arg0, arg0 = arg1, arg1 = tem; | |
4981 | ||
4982 | /* Handle addition of zero, then addition of an invariant. */ | |
4983 | if (arg1 == const0_rtx) | |
4984 | return arg0; | |
4985 | else if (GET_CODE (arg1) == CONST_INT || GET_CODE (arg1) == USE) | |
4986 | switch (GET_CODE (arg0)) | |
4987 | { | |
4988 | case CONST_INT: | |
4989 | case USE: | |
4990 | /* Both invariant. Only valid if sum is machine operand. | |
4991 | First strip off possible USE on first operand. */ | |
4992 | if (GET_CODE (arg0) == USE) | |
4993 | arg0 = XEXP (arg0, 0); | |
4994 | ||
4995 | tem = 0; | |
4996 | if (CONSTANT_P (arg0) && GET_CODE (arg1) == CONST_INT) | |
4997 | { | |
4998 | tem = plus_constant (arg0, INTVAL (arg1)); | |
4999 | if (GET_CODE (tem) != CONST_INT) | |
5000 | tem = gen_rtx (USE, mode, tem); | |
5001 | } | |
5002 | ||
5003 | return tem; | |
5004 | ||
5005 | case REG: | |
5006 | case MULT: | |
5007 | /* biv + invar or mult + invar. Return sum. */ | |
5008 | return gen_rtx (PLUS, mode, arg0, arg1); | |
5009 | ||
5010 | case PLUS: | |
5011 | /* (a + invar_1) + invar_2. Associate. */ | |
5012 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
5013 | XEXP (arg0, 0), | |
5014 | gen_rtx (PLUS, mode, | |
5015 | XEXP (arg0, 1), arg1)), | |
5016 | benefit); | |
5017 | ||
5018 | default: | |
5019 | abort (); | |
5020 | } | |
5021 | ||
5022 | /* Each argument must be either REG, PLUS, or MULT. Convert REG to | |
5023 | MULT to reduce cases. */ | |
5024 | if (GET_CODE (arg0) == REG) | |
5025 | arg0 = gen_rtx (MULT, mode, arg0, const1_rtx); | |
5026 | if (GET_CODE (arg1) == REG) | |
5027 | arg1 = gen_rtx (MULT, mode, arg1, const1_rtx); | |
5028 | ||
5029 | /* Now have PLUS + PLUS, PLUS + MULT, MULT + PLUS, or MULT + MULT. | |
5030 | Put a MULT first, leaving PLUS + PLUS, MULT + PLUS, or MULT + MULT. | |
5031 | Recurse to associate the second PLUS. */ | |
5032 | if (GET_CODE (arg1) == MULT) | |
5033 | tem = arg0, arg0 = arg1, arg1 = tem; | |
5034 | ||
5035 | if (GET_CODE (arg1) == PLUS) | |
5036 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
5037 | gen_rtx (PLUS, mode, | |
5038 | arg0, XEXP (arg1, 0)), | |
5039 | XEXP (arg1, 1)), | |
5040 | benefit); | |
5041 | ||
5042 | /* Now must have MULT + MULT. Distribute if same biv, else not giv. */ | |
5043 | if (GET_CODE (arg0) != MULT || GET_CODE (arg1) != MULT) | |
5044 | abort (); | |
5045 | ||
5046 | if (XEXP (arg0, 0) != XEXP (arg1, 0)) | |
5047 | return 0; | |
5048 | ||
5049 | return simplify_giv_expr (gen_rtx (MULT, mode, | |
5050 | XEXP (arg0, 0), | |
5051 | gen_rtx (PLUS, mode, | |
5052 | XEXP (arg0, 1), | |
5053 | XEXP (arg1, 1))), | |
5054 | benefit); | |
5055 | ||
5056 | case MINUS: | |
5057 | /* Handle "a - b" as "a + b * (-1)". */ | |
5058 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
5059 | XEXP (x, 0), | |
5060 | gen_rtx (MULT, mode, | |
5061 | XEXP (x, 1), constm1_rtx)), | |
5062 | benefit); | |
5063 | ||
5064 | case MULT: | |
5065 | arg0 = simplify_giv_expr (XEXP (x, 0), benefit); | |
5066 | arg1 = simplify_giv_expr (XEXP (x, 1), benefit); | |
5067 | if (arg0 == 0 || arg1 == 0) | |
5068 | return 0; | |
5069 | ||
5070 | /* Put constant last, CONST_INT last if both constant. */ | |
5071 | if ((GET_CODE (arg0) == USE || GET_CODE (arg0) == CONST_INT) | |
5072 | && GET_CODE (arg1) != CONST_INT) | |
5073 | tem = arg0, arg0 = arg1, arg1 = tem; | |
5074 | ||
5075 | /* If second argument is not now constant, not giv. */ | |
5076 | if (GET_CODE (arg1) != USE && GET_CODE (arg1) != CONST_INT) | |
5077 | return 0; | |
5078 | ||
5079 | /* Handle multiply by 0 or 1. */ | |
5080 | if (arg1 == const0_rtx) | |
5081 | return const0_rtx; | |
5082 | ||
5083 | else if (arg1 == const1_rtx) | |
5084 | return arg0; | |
5085 | ||
5086 | switch (GET_CODE (arg0)) | |
5087 | { | |
5088 | case REG: | |
5089 | /* biv * invar. Done. */ | |
5090 | return gen_rtx (MULT, mode, arg0, arg1); | |
5091 | ||
5092 | case CONST_INT: | |
5093 | /* Product of two constants. */ | |
5094 | return GEN_INT (INTVAL (arg0) * INTVAL (arg1)); | |
5095 | ||
5096 | case USE: | |
5097 | /* invar * invar. Not giv. */ | |
5098 | return 0; | |
5099 | ||
5100 | case MULT: | |
5101 | /* (a * invar_1) * invar_2. Associate. */ | |
5102 | return simplify_giv_expr (gen_rtx (MULT, mode, | |
5103 | XEXP (arg0, 0), | |
5104 | gen_rtx (MULT, mode, | |
5105 | XEXP (arg0, 1), arg1)), | |
5106 | benefit); | |
5107 | ||
5108 | case PLUS: | |
5109 | /* (a + invar_1) * invar_2. Distribute. */ | |
5110 | return simplify_giv_expr (gen_rtx (PLUS, mode, | |
5111 | gen_rtx (MULT, mode, | |
5112 | XEXP (arg0, 0), arg1), | |
5113 | gen_rtx (MULT, mode, | |
5114 | XEXP (arg0, 1), arg1)), | |
5115 | benefit); | |
5116 | ||
5117 | default: | |
5118 | abort (); | |
5119 | } | |
5120 | ||
5121 | case ASHIFT: | |
5122 | case LSHIFT: | |
5123 | /* Shift by constant is multiply by power of two. */ | |
5124 | if (GET_CODE (XEXP (x, 1)) != CONST_INT) | |
5125 | return 0; | |
5126 | ||
5127 | return simplify_giv_expr (gen_rtx (MULT, mode, | |
5128 | XEXP (x, 0), | |
5129 | GEN_INT ((HOST_WIDE_INT) 1 | |
5130 | << INTVAL (XEXP (x, 1)))), | |
5131 | benefit); | |
5132 | ||
5133 | case NEG: | |
5134 | /* "-a" is "a * (-1)" */ | |
5135 | return simplify_giv_expr (gen_rtx (MULT, mode, XEXP (x, 0), constm1_rtx), | |
5136 | benefit); | |
5137 | ||
5138 | case NOT: | |
5139 | /* "~a" is "-a - 1". Silly, but easy. */ | |
5140 | return simplify_giv_expr (gen_rtx (MINUS, mode, | |
5141 | gen_rtx (NEG, mode, XEXP (x, 0)), | |
5142 | const1_rtx), | |
5143 | benefit); | |
5144 | ||
5145 | case USE: | |
5146 | /* Already in proper form for invariant. */ | |
5147 | return x; | |
5148 | ||
5149 | case REG: | |
5150 | /* If this is a new register, we can't deal with it. */ | |
5151 | if (REGNO (x) >= max_reg_before_loop) | |
5152 | return 0; | |
5153 | ||
5154 | /* Check for biv or giv. */ | |
5155 | switch (reg_iv_type[REGNO (x)]) | |
5156 | { | |
5157 | case BASIC_INDUCT: | |
5158 | return x; | |
5159 | case GENERAL_INDUCT: | |
5160 | { | |
5161 | struct induction *v = reg_iv_info[REGNO (x)]; | |
5162 | ||
5163 | /* Form expression from giv and add benefit. Ensure this giv | |
5164 | can derive another and subtract any needed adjustment if so. */ | |
5165 | *benefit += v->benefit; | |
5166 | if (v->cant_derive) | |
5167 | return 0; | |
5168 | ||
5169 | tem = gen_rtx (PLUS, mode, gen_rtx (MULT, mode, | |
5170 | v->src_reg, v->mult_val), | |
5171 | v->add_val); | |
5172 | if (v->derive_adjustment) | |
5173 | tem = gen_rtx (MINUS, mode, tem, v->derive_adjustment); | |
5174 | return simplify_giv_expr (tem, benefit); | |
5175 | } | |
5176 | } | |
5177 | ||
5178 | /* Fall through to general case. */ | |
5179 | default: | |
5180 | /* If invariant, return as USE (unless CONST_INT). | |
5181 | Otherwise, not giv. */ | |
5182 | if (GET_CODE (x) == USE) | |
5183 | x = XEXP (x, 0); | |
5184 | ||
5185 | if (invariant_p (x) == 1) | |
5186 | { | |
5187 | if (GET_CODE (x) == CONST_INT) | |
5188 | return x; | |
5189 | else | |
5190 | return gen_rtx (USE, mode, x); | |
5191 | } | |
5192 | else | |
5193 | return 0; | |
5194 | } | |
5195 | } | |
5196 | \f | |
5197 | /* Help detect a giv that is calculated by several consecutive insns; | |
5198 | for example, | |
5199 | giv = biv * M | |
5200 | giv = giv + A | |
5201 | The caller has already identified the first insn P as having a giv as dest; | |
5202 | we check that all other insns that set the same register follow | |
5203 | immediately after P, that they alter nothing else, | |
5204 | and that the result of the last is still a giv. | |
5205 | ||
5206 | The value is 0 if the reg set in P is not really a giv. | |
5207 | Otherwise, the value is the amount gained by eliminating | |
5208 | all the consecutive insns that compute the value. | |
5209 | ||
5210 | FIRST_BENEFIT is the amount gained by eliminating the first insn, P. | |
5211 | SRC_REG is the reg of the biv; DEST_REG is the reg of the giv. | |
5212 | ||
5213 | The coefficients of the ultimate giv value are stored in | |
5214 | *MULT_VAL and *ADD_VAL. */ | |
5215 | ||
5216 | static int | |
5217 | consec_sets_giv (first_benefit, p, src_reg, dest_reg, | |
5218 | add_val, mult_val) | |
5219 | int first_benefit; | |
5220 | rtx p; | |
5221 | rtx src_reg; | |
5222 | rtx dest_reg; | |
5223 | rtx *add_val; | |
5224 | rtx *mult_val; | |
5225 | { | |
5226 | int count; | |
5227 | enum rtx_code code; | |
5228 | int benefit; | |
5229 | rtx temp; | |
5230 | rtx set; | |
5231 | ||
5232 | /* Indicate that this is a giv so that we can update the value produced in | |
5233 | each insn of the multi-insn sequence. | |
5234 | ||
5235 | This induction structure will be used only by the call to | |
5236 | general_induction_var below, so we can allocate it on our stack. | |
5237 | If this is a giv, our caller will replace the induct var entry with | |
5238 | a new induction structure. */ | |
5239 | struct induction *v | |
5240 | = (struct induction *) alloca (sizeof (struct induction)); | |
5241 | v->src_reg = src_reg; | |
5242 | v->mult_val = *mult_val; | |
5243 | v->add_val = *add_val; | |
5244 | v->benefit = first_benefit; | |
5245 | v->cant_derive = 0; | |
5246 | v->derive_adjustment = 0; | |
5247 | ||
5248 | reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT; | |
5249 | reg_iv_info[REGNO (dest_reg)] = v; | |
5250 | ||
5251 | count = n_times_set[REGNO (dest_reg)] - 1; | |
5252 | ||
5253 | while (count > 0) | |
5254 | { | |
5255 | p = NEXT_INSN (p); | |
5256 | code = GET_CODE (p); | |
5257 | ||
5258 | /* If libcall, skip to end of call sequence. */ | |
5259 | if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX))) | |
5260 | p = XEXP (temp, 0); | |
5261 | ||
5262 | if (code == INSN | |
5263 | && (set = single_set (p)) | |
5264 | && GET_CODE (SET_DEST (set)) == REG | |
5265 | && SET_DEST (set) == dest_reg | |
5266 | && ((benefit = general_induction_var (SET_SRC (set), &src_reg, | |
5267 | add_val, mult_val)) | |
5268 | /* Giv created by equivalent expression. */ | |
5269 | || ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX)) | |
5270 | && (benefit = general_induction_var (XEXP (temp, 0), &src_reg, | |
5271 | add_val, mult_val)))) | |
5272 | && src_reg == v->src_reg) | |
5273 | { | |
5274 | if (find_reg_note (p, REG_RETVAL, NULL_RTX)) | |
5275 | benefit += libcall_benefit (p); | |
5276 | ||
5277 | count--; | |
5278 | v->mult_val = *mult_val; | |
5279 | v->add_val = *add_val; | |
5280 | v->benefit = benefit; | |
5281 | } | |
5282 | else if (code != NOTE) | |
5283 | { | |
5284 | /* Allow insns that set something other than this giv to a | |
5285 | constant. Such insns are needed on machines which cannot | |
5286 | include long constants and should not disqualify a giv. */ | |
5287 | if (code == INSN | |
5288 | && (set = single_set (p)) | |
5289 | && SET_DEST (set) != dest_reg | |
5290 | && CONSTANT_P (SET_SRC (set))) | |
5291 | continue; | |
5292 | ||
5293 | reg_iv_type[REGNO (dest_reg)] = UNKNOWN_INDUCT; | |
5294 | return 0; | |
5295 | } | |
5296 | } | |
5297 | ||
5298 | return v->benefit; | |
5299 | } | |
5300 | \f | |
5301 | /* Return an rtx, if any, that expresses giv G2 as a function of the register | |
5302 | represented by G1. If no such expression can be found, or it is clear that | |
5303 | it cannot possibly be a valid address, 0 is returned. | |
5304 | ||
5305 | To perform the computation, we note that | |
5306 | G1 = a * v + b and | |
5307 | G2 = c * v + d | |
5308 | where `v' is the biv. | |
5309 | ||
5310 | So G2 = (c/a) * G1 + (d - b*c/a) */ | |
5311 | ||
5312 | #ifdef ADDRESS_COST | |
5313 | static rtx | |
5314 | express_from (g1, g2) | |
5315 | struct induction *g1, *g2; | |
5316 | { | |
5317 | rtx mult, add; | |
5318 | ||
5319 | /* The value that G1 will be multiplied by must be a constant integer. Also, | |
5320 | the only chance we have of getting a valid address is if b*c/a (see above | |
5321 | for notation) is also an integer. */ | |
5322 | if (GET_CODE (g1->mult_val) != CONST_INT | |
5323 | || GET_CODE (g2->mult_val) != CONST_INT | |
5324 | || GET_CODE (g1->add_val) != CONST_INT | |
5325 | || g1->mult_val == const0_rtx | |
5326 | || INTVAL (g2->mult_val) % INTVAL (g1->mult_val) != 0) | |
5327 | return 0; | |
5328 | ||
5329 | mult = GEN_INT (INTVAL (g2->mult_val) / INTVAL (g1->mult_val)); | |
5330 | add = plus_constant (g2->add_val, - INTVAL (g1->add_val) * INTVAL (mult)); | |
5331 | ||
5332 | /* Form simplified final result. */ | |
5333 | if (mult == const0_rtx) | |
5334 | return add; | |
5335 | else if (mult == const1_rtx) | |
5336 | mult = g1->dest_reg; | |
5337 | else | |
5338 | mult = gen_rtx (MULT, g2->mode, g1->dest_reg, mult); | |
5339 | ||
5340 | if (add == const0_rtx) | |
5341 | return mult; | |
5342 | else | |
5343 | return gen_rtx (PLUS, g2->mode, mult, add); | |
5344 | } | |
5345 | #endif | |
5346 | \f | |
5347 | /* Return 1 if giv G2 can be combined with G1. This means that G2 can use | |
5348 | (either directly or via an address expression) a register used to represent | |
5349 | G1. Set g2->new_reg to a represtation of G1 (normally just | |
5350 | g1->dest_reg). */ | |
5351 | ||
5352 | static int | |
5353 | combine_givs_p (g1, g2) | |
5354 | struct induction *g1, *g2; | |
5355 | { | |
5356 | rtx tem; | |
5357 | ||
5358 | /* If these givs are identical, they can be combined. */ | |
5359 | if (rtx_equal_p (g1->mult_val, g2->mult_val) | |
5360 | && rtx_equal_p (g1->add_val, g2->add_val)) | |
5361 | { | |
5362 | g2->new_reg = g1->dest_reg; | |
5363 | return 1; | |
5364 | } | |
5365 | ||
5366 | #ifdef ADDRESS_COST | |
5367 | /* If G2 can be expressed as a function of G1 and that function is valid | |
5368 | as an address and no more expensive than using a register for G2, | |
5369 | the expression of G2 in terms of G1 can be used. */ | |
5370 | if (g2->giv_type == DEST_ADDR | |
5371 | && (tem = express_from (g1, g2)) != 0 | |
5372 | && memory_address_p (g2->mem_mode, tem) | |
5373 | && ADDRESS_COST (tem) <= ADDRESS_COST (*g2->location)) | |
5374 | { | |
5375 | g2->new_reg = tem; | |
5376 | return 1; | |
5377 | } | |
5378 | #endif | |
5379 | ||
5380 | return 0; | |
5381 | } | |
5382 | \f | |
5383 | /* Check all pairs of givs for iv_class BL and see if any can be combined with | |
5384 | any other. If so, point SAME to the giv combined with and set NEW_REG to | |
5385 | be an expression (in terms of the other giv's DEST_REG) equivalent to the | |
5386 | giv. Also, update BENEFIT and related fields for cost/benefit analysis. */ | |
5387 | ||
5388 | static void | |
5389 | combine_givs (bl) | |
5390 | struct iv_class *bl; | |
5391 | { | |
5392 | struct induction *g1, *g2; | |
5393 | int pass; | |
5394 | ||
5395 | for (g1 = bl->giv; g1; g1 = g1->next_iv) | |
5396 | for (pass = 0; pass <= 1; pass++) | |
5397 | for (g2 = bl->giv; g2; g2 = g2->next_iv) | |
5398 | if (g1 != g2 | |
5399 | /* First try to combine with replaceable givs, then all givs. */ | |
5400 | && (g1->replaceable || pass == 1) | |
5401 | /* If either has already been combined or is to be ignored, can't | |
5402 | combine. */ | |
5403 | && ! g1->ignore && ! g2->ignore && ! g1->same && ! g2->same | |
5404 | /* If something has been based on G2, G2 cannot itself be based | |
5405 | on something else. */ | |
5406 | && ! g2->combined_with | |
5407 | && combine_givs_p (g1, g2)) | |
5408 | { | |
5409 | /* g2->new_reg set by `combine_givs_p' */ | |
5410 | g2->same = g1; | |
5411 | g1->combined_with = 1; | |
5412 | g1->benefit += g2->benefit; | |
5413 | /* ??? The new final_[bg]iv_value code does a much better job | |
5414 | of finding replaceable giv's, and hence this code may no | |
5415 | longer be necessary. */ | |
5416 | if (! g2->replaceable && REG_USERVAR_P (g2->dest_reg)) | |
5417 | g1->benefit -= copy_cost; | |
5418 | g1->lifetime += g2->lifetime; | |
5419 | g1->times_used += g2->times_used; | |
5420 | ||
5421 | if (loop_dump_stream) | |
5422 | fprintf (loop_dump_stream, "giv at %d combined with giv at %d\n", | |
5423 | INSN_UID (g2->insn), INSN_UID (g1->insn)); | |
5424 | } | |
5425 | } | |
5426 | \f | |
5427 | /* EMIT code before INSERT_BEFORE to set REG = B * M + A. */ | |
5428 | ||
5429 | void | |
5430 | emit_iv_add_mult (b, m, a, reg, insert_before) | |
5431 | rtx b; /* initial value of basic induction variable */ | |
5432 | rtx m; /* multiplicative constant */ | |
5433 | rtx a; /* additive constant */ | |
5434 | rtx reg; /* destination register */ | |
5435 | rtx insert_before; | |
5436 | { | |
5437 | rtx seq; | |
5438 | rtx result; | |
5439 | ||
5440 | /* Prevent unexpected sharing of these rtx. */ | |
5441 | a = copy_rtx (a); | |
5442 | b = copy_rtx (b); | |
5443 | ||
5444 | /* Increase the lifetime of any invariants moved further in code. */ | |
5445 | update_reg_last_use (a, insert_before); | |
5446 | update_reg_last_use (b, insert_before); | |
5447 | update_reg_last_use (m, insert_before); | |
5448 | ||
5449 | start_sequence (); | |
5450 | result = expand_mult_add (b, reg, m, a, GET_MODE (reg), 0); | |
5451 | if (reg != result) | |
5452 | emit_move_insn (reg, result); | |
5453 | seq = gen_sequence (); | |
5454 | end_sequence (); | |
5455 | ||
5456 | emit_insn_before (seq, insert_before); | |
5457 | } | |
5458 | \f | |
5459 | /* Test whether A * B can be computed without | |
5460 | an actual multiply insn. Value is 1 if so. */ | |
5461 | ||
5462 | static int | |
5463 | product_cheap_p (a, b) | |
5464 | rtx a; | |
5465 | rtx b; | |
5466 | { | |
5467 | int i; | |
5468 | rtx tmp; | |
5469 | struct obstack *old_rtl_obstack = rtl_obstack; | |
5470 | char *storage = (char *) obstack_alloc (&temp_obstack, 0); | |
5471 | int win = 1; | |
5472 | ||
5473 | /* If only one is constant, make it B. */ | |
5474 | if (GET_CODE (a) == CONST_INT) | |
5475 | tmp = a, a = b, b = tmp; | |
5476 | ||
5477 | /* If first constant, both constant, so don't need multiply. */ | |
5478 | if (GET_CODE (a) == CONST_INT) | |
5479 | return 1; | |
5480 | ||
5481 | /* If second not constant, neither is constant, so would need multiply. */ | |
5482 | if (GET_CODE (b) != CONST_INT) | |
5483 | return 0; | |
5484 | ||
5485 | /* One operand is constant, so might not need multiply insn. Generate the | |
5486 | code for the multiply and see if a call or multiply, or long sequence | |
5487 | of insns is generated. */ | |
5488 | ||
5489 | rtl_obstack = &temp_obstack; | |
5490 | start_sequence (); | |
5491 | expand_mult (GET_MODE (a), a, b, NULL_RTX, 0); | |
5492 | tmp = gen_sequence (); | |
5493 | end_sequence (); | |
5494 | ||
5495 | if (GET_CODE (tmp) == SEQUENCE) | |
5496 | { | |
5497 | if (XVEC (tmp, 0) == 0) | |
5498 | win = 1; | |
5499 | else if (XVECLEN (tmp, 0) > 3) | |
5500 | win = 0; | |
5501 | else | |
5502 | for (i = 0; i < XVECLEN (tmp, 0); i++) | |
5503 | { | |
5504 | rtx insn = XVECEXP (tmp, 0, i); | |
5505 | ||
5506 | if (GET_CODE (insn) != INSN | |
5507 | || (GET_CODE (PATTERN (insn)) == SET | |
5508 | && GET_CODE (SET_SRC (PATTERN (insn))) == MULT) | |
5509 | || (GET_CODE (PATTERN (insn)) == PARALLEL | |
5510 | && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET | |
5511 | && GET_CODE (SET_SRC (XVECEXP (PATTERN (insn), 0, 0))) == MULT)) | |
5512 | { | |
5513 | win = 0; | |
5514 | break; | |
5515 | } | |
5516 | } | |
5517 | } | |
5518 | else if (GET_CODE (tmp) == SET | |
5519 | && GET_CODE (SET_SRC (tmp)) == MULT) | |
5520 | win = 0; | |
5521 | else if (GET_CODE (tmp) == PARALLEL | |
5522 | && GET_CODE (XVECEXP (tmp, 0, 0)) == SET | |
5523 | && GET_CODE (SET_SRC (XVECEXP (tmp, 0, 0))) == MULT) | |
5524 | win = 0; | |
5525 | ||
5526 | /* Free any storage we obtained in generating this multiply and restore rtl | |
5527 | allocation to its normal obstack. */ | |
5528 | obstack_free (&temp_obstack, storage); | |
5529 | rtl_obstack = old_rtl_obstack; | |
5530 | ||
5531 | return win; | |
5532 | } | |
5533 | \f | |
5534 | /* Check to see if loop can be terminated by a "decrement and branch until | |
5535 | zero" instruction. If so, add a REG_NONNEG note to the branch insn if so. | |
5536 | Also try reversing an increment loop to a decrement loop | |
5537 | to see if the optimization can be performed. | |
5538 | Value is nonzero if optimization was performed. */ | |
5539 | ||
5540 | /* This is useful even if the architecture doesn't have such an insn, | |
5541 | because it might change a loops which increments from 0 to n to a loop | |
5542 | which decrements from n to 0. A loop that decrements to zero is usually | |
5543 | faster than one that increments from zero. */ | |
5544 | ||
5545 | /* ??? This could be rewritten to use some of the loop unrolling procedures, | |
5546 | such as approx_final_value, biv_total_increment, loop_iterations, and | |
5547 | final_[bg]iv_value. */ | |
5548 | ||
5549 | static int | |
5550 | check_dbra_loop (loop_end, insn_count, loop_start) | |
5551 | rtx loop_end; | |
5552 | int insn_count; | |
5553 | rtx loop_start; | |
5554 | { | |
5555 | struct iv_class *bl; | |
5556 | rtx reg; | |
5557 | rtx jump_label; | |
5558 | rtx final_value; | |
5559 | rtx start_value; | |
5560 | enum rtx_code branch_code; | |
5561 | rtx new_add_val; | |
5562 | rtx comparison; | |
5563 | rtx before_comparison; | |
5564 | rtx p; | |
5565 | ||
5566 | /* If last insn is a conditional branch, and the insn before tests a | |
5567 | register value, try to optimize it. Otherwise, we can't do anything. */ | |
5568 | ||
5569 | comparison = get_condition_for_loop (PREV_INSN (loop_end)); | |
5570 | if (comparison == 0) | |
5571 | return 0; | |
5572 | ||
5573 | /* Check all of the bivs to see if the compare uses one of them. | |
5574 | Skip biv's set more than once because we can't guarantee that | |
5575 | it will be zero on the last iteration. Also skip if the biv is | |
5576 | used between its update and the test insn. */ | |
5577 | ||
5578 | for (bl = loop_iv_list; bl; bl = bl->next) | |
5579 | { | |
5580 | if (bl->biv_count == 1 | |
5581 | && bl->biv->dest_reg == XEXP (comparison, 0) | |
5582 | && ! reg_used_between_p (regno_reg_rtx[bl->regno], bl->biv->insn, | |
5583 | PREV_INSN (PREV_INSN (loop_end)))) | |
5584 | break; | |
5585 | } | |
5586 | ||
5587 | if (! bl) | |
5588 | return 0; | |
5589 | ||
5590 | /* Look for the case where the basic induction variable is always | |
5591 | nonnegative, and equals zero on the last iteration. | |
5592 | In this case, add a reg_note REG_NONNEG, which allows the | |
5593 | m68k DBRA instruction to be used. */ | |
5594 | ||
5595 | if (((GET_CODE (comparison) == GT | |
5596 | && GET_CODE (XEXP (comparison, 1)) == CONST_INT | |
5597 | && INTVAL (XEXP (comparison, 1)) == -1) | |
5598 | || (GET_CODE (comparison) == NE && XEXP (comparison, 1) == const0_rtx)) | |
5599 | && GET_CODE (bl->biv->add_val) == CONST_INT | |
5600 | && INTVAL (bl->biv->add_val) < 0) | |
5601 | { | |
5602 | /* Initial value must be greater than 0, | |
5603 | init_val % -dec_value == 0 to ensure that it equals zero on | |
5604 | the last iteration */ | |
5605 | ||
5606 | if (GET_CODE (bl->initial_value) == CONST_INT | |
5607 | && INTVAL (bl->initial_value) > 0 | |
5608 | && (INTVAL (bl->initial_value) % | |
5609 | (-INTVAL (bl->biv->add_val))) == 0) | |
5610 | { | |
5611 | /* register always nonnegative, add REG_NOTE to branch */ | |
5612 | REG_NOTES (PREV_INSN (loop_end)) | |
5613 | = gen_rtx (EXPR_LIST, REG_NONNEG, NULL_RTX, | |
5614 | REG_NOTES (PREV_INSN (loop_end))); | |
5615 | bl->nonneg = 1; | |
5616 | ||
5617 | return 1; | |
5618 | } | |
5619 | ||
5620 | /* If the decrement is 1 and the value was tested as >= 0 before | |
5621 | the loop, then we can safely optimize. */ | |
5622 | for (p = loop_start; p; p = PREV_INSN (p)) | |
5623 | { | |
5624 | if (GET_CODE (p) == CODE_LABEL) | |
5625 | break; | |
5626 | if (GET_CODE (p) != JUMP_INSN) | |
5627 | continue; | |
5628 | ||
5629 | before_comparison = get_condition_for_loop (p); | |
5630 | if (before_comparison | |
5631 | && XEXP (before_comparison, 0) == bl->biv->dest_reg | |
5632 | && GET_CODE (before_comparison) == LT | |
5633 | && XEXP (before_comparison, 1) == const0_rtx | |
5634 | && ! reg_set_between_p (bl->biv->dest_reg, p, loop_start) | |
5635 | && INTVAL (bl->biv->add_val) == -1) | |
5636 | { | |
5637 | REG_NOTES (PREV_INSN (loop_end)) | |
5638 | = gen_rtx (EXPR_LIST, REG_NONNEG, NULL_RTX, | |
5639 | REG_NOTES (PREV_INSN (loop_end))); | |
5640 | bl->nonneg = 1; | |
5641 | ||
5642 | return 1; | |
5643 | } | |
5644 | } | |
5645 | } | |
5646 | else if (num_mem_sets <= 1) | |
5647 | { | |
5648 | /* Try to change inc to dec, so can apply above optimization. */ | |
5649 | /* Can do this if: | |
5650 | all registers modified are induction variables or invariant, | |
5651 | all memory references have non-overlapping addresses | |
5652 | (obviously true if only one write) | |
5653 | allow 2 insns for the compare/jump at the end of the loop. */ | |
5654 | int num_nonfixed_reads = 0; | |
5655 | /* 1 if the iteration var is used only to count iterations. */ | |
5656 | int no_use_except_counting = 0; | |
5657 | ||
5658 | for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) | |
5659 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i') | |
5660 | num_nonfixed_reads += count_nonfixed_reads (PATTERN (p)); | |
5661 | ||
5662 | if (bl->giv_count == 0 | |
5663 | && ! loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
5664 | { | |
5665 | rtx bivreg = regno_reg_rtx[bl->regno]; | |
5666 | ||
5667 | /* If there are no givs for this biv, and the only exit is the | |
5668 | fall through at the end of the the loop, then | |
5669 | see if perhaps there are no uses except to count. */ | |
5670 | no_use_except_counting = 1; | |
5671 | for (p = loop_start; p != loop_end; p = NEXT_INSN (p)) | |
5672 | if (GET_RTX_CLASS (GET_CODE (p)) == 'i') | |
5673 | { | |
5674 | rtx set = single_set (p); | |
5675 | ||
5676 | if (set && GET_CODE (SET_DEST (set)) == REG | |
5677 | && REGNO (SET_DEST (set)) == bl->regno) | |
5678 | /* An insn that sets the biv is okay. */ | |
5679 | ; | |
5680 | else if (p == prev_nonnote_insn (prev_nonnote_insn (loop_end)) | |
5681 | || p == prev_nonnote_insn (loop_end)) | |
5682 | /* Don't bother about the end test. */ | |
5683 | ; | |
5684 | else if (reg_mentioned_p (bivreg, PATTERN (p))) | |
5685 | /* Any other use of the biv is no good. */ | |
5686 | { | |
5687 | no_use_except_counting = 0; | |
5688 | break; | |
5689 | } | |
5690 | } | |
5691 | } | |
5692 | ||
5693 | /* This code only acts for innermost loops. Also it simplifies | |
5694 | the memory address check by only reversing loops with | |
5695 | zero or one memory access. | |
5696 | Two memory accesses could involve parts of the same array, | |
5697 | and that can't be reversed. */ | |
5698 | ||
5699 | if (num_nonfixed_reads <= 1 | |
5700 | && !loop_has_call | |
5701 | && !loop_has_volatile | |
5702 | && (no_use_except_counting | |
5703 | || (bl->giv_count + bl->biv_count + num_mem_sets | |
5704 | + num_movables + 2 == insn_count))) | |
5705 | { | |
5706 | rtx condition = get_condition_for_loop (PREV_INSN (loop_end)); | |
5707 | int win; | |
5708 | rtx tem; | |
5709 | ||
5710 | /* Loop can be reversed. */ | |
5711 | if (loop_dump_stream) | |
5712 | fprintf (loop_dump_stream, "Can reverse loop\n"); | |
5713 | ||
5714 | /* Now check other conditions: | |
5715 | initial_value must be zero, | |
5716 | final_value % add_val == 0, so that when reversed, the | |
5717 | biv will be zero on the last iteration. | |
5718 | ||
5719 | This test can probably be improved since +/- 1 in the constant | |
5720 | can be obtained by changing LT to LE and vice versa; this is | |
5721 | confusing. */ | |
5722 | ||
5723 | if (comparison && bl->initial_value == const0_rtx | |
5724 | && GET_CODE (XEXP (comparison, 1)) == CONST_INT | |
5725 | /* LE gets turned into LT */ | |
5726 | && GET_CODE (comparison) == LT | |
5727 | && (INTVAL (XEXP (comparison, 1)) | |
5728 | % INTVAL (bl->biv->add_val)) == 0) | |
5729 | { | |
5730 | /* Register will always be nonnegative, with value | |
5731 | 0 on last iteration if loop reversed */ | |
5732 | ||
5733 | /* Save some info needed to produce the new insns. */ | |
5734 | reg = bl->biv->dest_reg; | |
5735 | jump_label = XEXP (SET_SRC (PATTERN (PREV_INSN (loop_end))), 1); | |
5736 | new_add_val = GEN_INT (- INTVAL (bl->biv->add_val)); | |
5737 | ||
5738 | final_value = XEXP (comparison, 1); | |
5739 | start_value = GEN_INT (INTVAL (XEXP (comparison, 1)) | |
5740 | - INTVAL (bl->biv->add_val)); | |
5741 | ||
5742 | /* Initialize biv to start_value before loop start. | |
5743 | The old initializing insn will be deleted as a | |
5744 | dead store by flow.c. */ | |
5745 | emit_insn_before (gen_move_insn (reg, start_value), loop_start); | |
5746 | ||
5747 | /* Add insn to decrement register, and delete insn | |
5748 | that incremented the register. */ | |
5749 | p = emit_insn_before (gen_add2_insn (reg, new_add_val), | |
5750 | bl->biv->insn); | |
5751 | delete_insn (bl->biv->insn); | |
5752 | ||
5753 | /* Update biv info to reflect its new status. */ | |
5754 | bl->biv->insn = p; | |
5755 | bl->initial_value = start_value; | |
5756 | bl->biv->add_val = new_add_val; | |
5757 | ||
5758 | /* Inc LABEL_NUSES so that delete_insn will | |
5759 | not delete the label. */ | |
5760 | LABEL_NUSES (XEXP (jump_label, 0)) ++; | |
5761 | ||
5762 | /* Emit an insn after the end of the loop to set the biv's | |
5763 | proper exit value if it is used anywhere outside the loop. */ | |
5764 | if ((regno_last_uid[bl->regno] | |
5765 | != INSN_UID (PREV_INSN (PREV_INSN (loop_end)))) | |
5766 | || ! bl->init_insn | |
5767 | || regno_first_uid[bl->regno] != INSN_UID (bl->init_insn)) | |
5768 | emit_insn_after (gen_move_insn (reg, final_value), | |
5769 | loop_end); | |
5770 | ||
5771 | /* Delete compare/branch at end of loop. */ | |
5772 | delete_insn (PREV_INSN (loop_end)); | |
5773 | delete_insn (PREV_INSN (loop_end)); | |
5774 | ||
5775 | /* Add new compare/branch insn at end of loop. */ | |
5776 | start_sequence (); | |
5777 | emit_cmp_insn (reg, const0_rtx, GE, NULL_RTX, | |
5778 | GET_MODE (reg), 0, 0); | |
5779 | emit_jump_insn (gen_bge (XEXP (jump_label, 0))); | |
5780 | tem = gen_sequence (); | |
5781 | end_sequence (); | |
5782 | emit_jump_insn_before (tem, loop_end); | |
5783 | ||
5784 | for (tem = PREV_INSN (loop_end); | |
5785 | tem && GET_CODE (tem) != JUMP_INSN; tem = PREV_INSN (tem)) | |
5786 | ; | |
5787 | if (tem) | |
5788 | { | |
5789 | JUMP_LABEL (tem) = XEXP (jump_label, 0); | |
5790 | ||
5791 | /* Increment of LABEL_NUSES done above. */ | |
5792 | /* Register is now always nonnegative, | |
5793 | so add REG_NONNEG note to the branch. */ | |
5794 | REG_NOTES (tem) = gen_rtx (EXPR_LIST, REG_NONNEG, NULL_RTX, | |
5795 | REG_NOTES (tem)); | |
5796 | } | |
5797 | ||
5798 | bl->nonneg = 1; | |
5799 | ||
5800 | /* Mark that this biv has been reversed. Each giv which depends | |
5801 | on this biv, and which is also live past the end of the loop | |
5802 | will have to be fixed up. */ | |
5803 | ||
5804 | bl->reversed = 1; | |
5805 | ||
5806 | if (loop_dump_stream) | |
5807 | fprintf (loop_dump_stream, | |
5808 | "Reversed loop and added reg_nonneg\n"); | |
5809 | ||
5810 | return 1; | |
5811 | } | |
5812 | } | |
5813 | } | |
5814 | ||
5815 | return 0; | |
5816 | } | |
5817 | \f | |
5818 | /* Verify whether the biv BL appears to be eliminable, | |
5819 | based on the insns in the loop that refer to it. | |
5820 | LOOP_START is the first insn of the loop, and END is the end insn. | |
5821 | ||
5822 | If ELIMINATE_P is non-zero, actually do the elimination. | |
5823 | ||
5824 | THRESHOLD and INSN_COUNT are from loop_optimize and are used to | |
5825 | determine whether invariant insns should be placed inside or at the | |
5826 | start of the loop. */ | |
5827 | ||
5828 | static int | |
5829 | maybe_eliminate_biv (bl, loop_start, end, eliminate_p, threshold, insn_count) | |
5830 | struct iv_class *bl; | |
5831 | rtx loop_start; | |
5832 | rtx end; | |
5833 | int eliminate_p; | |
5834 | int threshold, insn_count; | |
5835 | { | |
5836 | rtx reg = bl->biv->dest_reg; | |
5837 | rtx p, set; | |
5838 | struct induction *v; | |
5839 | ||
5840 | /* Scan all insns in the loop, stopping if we find one that uses the | |
5841 | biv in a way that we cannot eliminate. */ | |
5842 | ||
5843 | for (p = loop_start; p != end; p = NEXT_INSN (p)) | |
5844 | { | |
5845 | enum rtx_code code = GET_CODE (p); | |
5846 | rtx where = threshold >= insn_count ? loop_start : p; | |
5847 | ||
5848 | if ((code == INSN || code == JUMP_INSN || code == CALL_INSN) | |
5849 | && reg_mentioned_p (reg, PATTERN (p)) | |
5850 | && ! maybe_eliminate_biv_1 (PATTERN (p), p, bl, eliminate_p, where)) | |
5851 | { | |
5852 | if (loop_dump_stream) | |
5853 | fprintf (loop_dump_stream, | |
5854 | "Cannot eliminate biv %d: biv used in insn %d.\n", | |
5855 | bl->regno, INSN_UID (p)); | |
5856 | break; | |
5857 | } | |
5858 | } | |
5859 | ||
5860 | if (p == end) | |
5861 | { | |
5862 | if (loop_dump_stream) | |
5863 | fprintf (loop_dump_stream, "biv %d %s eliminated.\n", | |
5864 | bl->regno, eliminate_p ? "was" : "can be"); | |
5865 | return 1; | |
5866 | } | |
5867 | ||
5868 | return 0; | |
5869 | } | |
5870 | \f | |
5871 | /* If BL appears in X (part of the pattern of INSN), see if we can | |
5872 | eliminate its use. If so, return 1. If not, return 0. | |
5873 | ||
5874 | If BIV does not appear in X, return 1. | |
5875 | ||
5876 | If ELIMINATE_P is non-zero, actually do the elimination. WHERE indicates | |
5877 | where extra insns should be added. Depending on how many items have been | |
5878 | moved out of the loop, it will either be before INSN or at the start of | |
5879 | the loop. */ | |
5880 | ||
5881 | static int | |
5882 | maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where) | |
5883 | rtx x, insn; | |
5884 | struct iv_class *bl; | |
5885 | int eliminate_p; | |
5886 | rtx where; | |
5887 | { | |
5888 | enum rtx_code code = GET_CODE (x); | |
5889 | rtx reg = bl->biv->dest_reg; | |
5890 | enum machine_mode mode = GET_MODE (reg); | |
5891 | struct induction *v; | |
5892 | rtx arg, new, tem; | |
5893 | int arg_operand; | |
5894 | char *fmt; | |
5895 | int i, j; | |
5896 | ||
5897 | switch (code) | |
5898 | { | |
5899 | case REG: | |
5900 | /* If we haven't already been able to do something with this BIV, | |
5901 | we can't eliminate it. */ | |
5902 | if (x == reg) | |
5903 | return 0; | |
5904 | return 1; | |
5905 | ||
5906 | case SET: | |
5907 | /* If this sets the BIV, it is not a problem. */ | |
5908 | if (SET_DEST (x) == reg) | |
5909 | return 1; | |
5910 | ||
5911 | /* If this is an insn that defines a giv, it is also ok because | |
5912 | it will go away when the giv is reduced. */ | |
5913 | for (v = bl->giv; v; v = v->next_iv) | |
5914 | if (v->giv_type == DEST_REG && SET_DEST (x) == v->dest_reg) | |
5915 | return 1; | |
5916 | ||
5917 | #ifdef HAVE_cc0 | |
5918 | if (SET_DEST (x) == cc0_rtx && SET_SRC (x) == reg) | |
5919 | { | |
5920 | /* Can replace with any giv that was reduced and | |
5921 | that has (MULT_VAL != 0) and (ADD_VAL == 0). | |
5922 | Require a constant for MULT_VAL, so we know it's nonzero. */ | |
5923 | ||
5924 | for (v = bl->giv; v; v = v->next_iv) | |
5925 | if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx | |
5926 | && v->add_val == const0_rtx | |
5927 | && ! v->ignore && ! v->maybe_dead | |
5928 | && v->mode == mode) | |
5929 | { | |
5930 | if (! eliminate_p) | |
5931 | return 1; | |
5932 | ||
5933 | /* If the giv has the opposite direction of change, | |
5934 | then reverse the comparison. */ | |
5935 | if (INTVAL (v->mult_val) < 0) | |
5936 | new = gen_rtx (COMPARE, GET_MODE (v->new_reg), | |
5937 | const0_rtx, v->new_reg); | |
5938 | else | |
5939 | new = v->new_reg; | |
5940 | ||
5941 | /* We can probably test that giv's reduced reg. */ | |
5942 | if (validate_change (insn, &SET_SRC (x), new, 0)) | |
5943 | return 1; | |
5944 | } | |
5945 | ||
5946 | /* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0); | |
5947 | replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL). | |
5948 | Require a constant for MULT_VAL, so we know it's nonzero. */ | |
5949 | ||
5950 | for (v = bl->giv; v; v = v->next_iv) | |
5951 | if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx | |
5952 | && ! v->ignore && ! v->maybe_dead | |
5953 | && v->mode == mode) | |
5954 | { | |
5955 | if (! eliminate_p) | |
5956 | return 1; | |
5957 | ||
5958 | /* If the giv has the opposite direction of change, | |
5959 | then reverse the comparison. */ | |
5960 | if (INTVAL (v->mult_val) < 0) | |
5961 | new = gen_rtx (COMPARE, VOIDmode, copy_rtx (v->add_val), | |
5962 | v->new_reg); | |
5963 | else | |
5964 | new = gen_rtx (COMPARE, VOIDmode, v->new_reg, | |
5965 | copy_rtx (v->add_val)); | |
5966 | ||
5967 | /* Replace biv with the giv's reduced register. */ | |
5968 | update_reg_last_use (v->add_val, insn); | |
5969 | if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0)) | |
5970 | return 1; | |
5971 | ||
5972 | /* Insn doesn't support that constant or invariant. Copy it | |
5973 | into a register (it will be a loop invariant.) */ | |
5974 | tem = gen_reg_rtx (GET_MODE (v->new_reg)); | |
5975 | ||
5976 | emit_insn_before (gen_move_insn (tem, copy_rtx (v->add_val)), | |
5977 | where); | |
5978 | ||
5979 | if (validate_change (insn, &SET_SRC (PATTERN (insn)), | |
5980 | gen_rtx (COMPARE, VOIDmode, | |
5981 | v->new_reg, tem), 0)) | |
5982 | return 1; | |
5983 | } | |
5984 | } | |
5985 | #endif | |
5986 | break; | |
5987 | ||
5988 | case COMPARE: | |
5989 | case EQ: case NE: | |
5990 | case GT: case GE: case GTU: case GEU: | |
5991 | case LT: case LE: case LTU: case LEU: | |
5992 | /* See if either argument is the biv. */ | |
5993 | if (XEXP (x, 0) == reg) | |
5994 | arg = XEXP (x, 1), arg_operand = 1; | |
5995 | else if (XEXP (x, 1) == reg) | |
5996 | arg = XEXP (x, 0), arg_operand = 0; | |
5997 | else | |
5998 | break; | |
5999 | ||
6000 | if (CONSTANT_P (arg)) | |
6001 | { | |
6002 | /* First try to replace with any giv that has constant positive | |
6003 | mult_val and constant add_val. We might be able to support | |
6004 | negative mult_val, but it seems complex to do it in general. */ | |
6005 | ||
6006 | for (v = bl->giv; v; v = v->next_iv) | |
6007 | if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0 | |
6008 | && CONSTANT_P (v->add_val) | |
6009 | && ! v->ignore && ! v->maybe_dead | |
6010 | && v->mode == mode) | |
6011 | { | |
6012 | if (! eliminate_p) | |
6013 | return 1; | |
6014 | ||
6015 | /* Replace biv with the giv's reduced reg. */ | |
6016 | XEXP (x, 1-arg_operand) = v->new_reg; | |
6017 | ||
6018 | /* If all constants are actually constant integers and | |
6019 | the derived constant can be directly placed in the COMPARE, | |
6020 | do so. */ | |
6021 | if (GET_CODE (arg) == CONST_INT | |
6022 | && GET_CODE (v->mult_val) == CONST_INT | |
6023 | && GET_CODE (v->add_val) == CONST_INT | |
6024 | && validate_change (insn, &XEXP (x, arg_operand), | |
6025 | GEN_INT (INTVAL (arg) | |
6026 | * INTVAL (v->mult_val) | |
6027 | + INTVAL (v->add_val)), 0)) | |
6028 | return 1; | |
6029 | ||
6030 | /* Otherwise, load it into a register. */ | |
6031 | tem = gen_reg_rtx (mode); | |
6032 | emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where); | |
6033 | if (validate_change (insn, &XEXP (x, arg_operand), tem, 0)) | |
6034 | return 1; | |
6035 | ||
6036 | /* If that failed, put back the change we made above. */ | |
6037 | XEXP (x, 1-arg_operand) = reg; | |
6038 | } | |
6039 | ||
6040 | /* Look for giv with positive constant mult_val and nonconst add_val. | |
6041 | Insert insns to calculate new compare value. */ | |
6042 | ||
6043 | for (v = bl->giv; v; v = v->next_iv) | |
6044 | if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0 | |
6045 | && ! v->ignore && ! v->maybe_dead | |
6046 | && v->mode == mode) | |
6047 | { | |
6048 | rtx tem; | |
6049 | ||
6050 | if (! eliminate_p) | |
6051 | return 1; | |
6052 | ||
6053 | tem = gen_reg_rtx (mode); | |
6054 | ||
6055 | /* Replace biv with giv's reduced register. */ | |
6056 | validate_change (insn, &XEXP (x, 1 - arg_operand), | |
6057 | v->new_reg, 1); | |
6058 | ||
6059 | /* Compute value to compare against. */ | |
6060 | emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where); | |
6061 | /* Use it in this insn. */ | |
6062 | validate_change (insn, &XEXP (x, arg_operand), tem, 1); | |
6063 | if (apply_change_group ()) | |
6064 | return 1; | |
6065 | } | |
6066 | } | |
6067 | else if (GET_CODE (arg) == REG || GET_CODE (arg) == MEM) | |
6068 | { | |
6069 | if (invariant_p (arg) == 1) | |
6070 | { | |
6071 | /* Look for giv with constant positive mult_val and nonconst | |
6072 | add_val. Insert insns to compute new compare value. */ | |
6073 | ||
6074 | for (v = bl->giv; v; v = v->next_iv) | |
6075 | if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0 | |
6076 | && ! v->ignore && ! v->maybe_dead | |
6077 | && v->mode == mode) | |
6078 | { | |
6079 | rtx tem; | |
6080 | ||
6081 | if (! eliminate_p) | |
6082 | return 1; | |
6083 | ||
6084 | tem = gen_reg_rtx (mode); | |
6085 | ||
6086 | /* Replace biv with giv's reduced register. */ | |
6087 | validate_change (insn, &XEXP (x, 1 - arg_operand), | |
6088 | v->new_reg, 1); | |
6089 | ||
6090 | /* Compute value to compare against. */ | |
6091 | emit_iv_add_mult (arg, v->mult_val, v->add_val, | |
6092 | tem, where); | |
6093 | validate_change (insn, &XEXP (x, arg_operand), tem, 1); | |
6094 | if (apply_change_group ()) | |
6095 | return 1; | |
6096 | } | |
6097 | } | |
6098 | ||
6099 | /* This code has problems. Basically, you can't know when | |
6100 | seeing if we will eliminate BL, whether a particular giv | |
6101 | of ARG will be reduced. If it isn't going to be reduced, | |
6102 | we can't eliminate BL. We can try forcing it to be reduced, | |
6103 | but that can generate poor code. | |
6104 | ||
6105 | The problem is that the benefit of reducing TV, below should | |
6106 | be increased if BL can actually be eliminated, but this means | |
6107 | we might have to do a topological sort of the order in which | |
6108 | we try to process biv. It doesn't seem worthwhile to do | |
6109 | this sort of thing now. */ | |
6110 | ||
6111 | #if 0 | |
6112 | /* Otherwise the reg compared with had better be a biv. */ | |
6113 | if (GET_CODE (arg) != REG | |
6114 | || reg_iv_type[REGNO (arg)] != BASIC_INDUCT) | |
6115 | return 0; | |
6116 | ||
6117 | /* Look for a pair of givs, one for each biv, | |
6118 | with identical coefficients. */ | |
6119 | for (v = bl->giv; v; v = v->next_iv) | |
6120 | { | |
6121 | struct induction *tv; | |
6122 | ||
6123 | if (v->ignore || v->maybe_dead || v->mode != mode) | |
6124 | continue; | |
6125 | ||
6126 | for (tv = reg_biv_class[REGNO (arg)]->giv; tv; tv = tv->next_iv) | |
6127 | if (! tv->ignore && ! tv->maybe_dead | |
6128 | && rtx_equal_p (tv->mult_val, v->mult_val) | |
6129 | && rtx_equal_p (tv->add_val, v->add_val) | |
6130 | && tv->mode == mode) | |
6131 | { | |
6132 | if (! eliminate_p) | |
6133 | return 1; | |
6134 | ||
6135 | /* Replace biv with its giv's reduced reg. */ | |
6136 | XEXP (x, 1-arg_operand) = v->new_reg; | |
6137 | /* Replace other operand with the other giv's | |
6138 | reduced reg. */ | |
6139 | XEXP (x, arg_operand) = tv->new_reg; | |
6140 | return 1; | |
6141 | } | |
6142 | } | |
6143 | #endif | |
6144 | } | |
6145 | ||
6146 | /* If we get here, the biv can't be eliminated. */ | |
6147 | return 0; | |
6148 | ||
6149 | case MEM: | |
6150 | /* If this address is a DEST_ADDR giv, it doesn't matter if the | |
6151 | biv is used in it, since it will be replaced. */ | |
6152 | for (v = bl->giv; v; v = v->next_iv) | |
6153 | if (v->giv_type == DEST_ADDR && v->location == &XEXP (x, 0)) | |
6154 | return 1; | |
6155 | break; | |
6156 | } | |
6157 | ||
6158 | /* See if any subexpression fails elimination. */ | |
6159 | fmt = GET_RTX_FORMAT (code); | |
6160 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
6161 | { | |
6162 | switch (fmt[i]) | |
6163 | { | |
6164 | case 'e': | |
6165 | if (! maybe_eliminate_biv_1 (XEXP (x, i), insn, bl, | |
6166 | eliminate_p, where)) | |
6167 | return 0; | |
6168 | break; | |
6169 | ||
6170 | case 'E': | |
6171 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
6172 | if (! maybe_eliminate_biv_1 (XVECEXP (x, i, j), insn, bl, | |
6173 | eliminate_p, where)) | |
6174 | return 0; | |
6175 | break; | |
6176 | } | |
6177 | } | |
6178 | ||
6179 | return 1; | |
6180 | } | |
6181 | \f | |
6182 | /* Return nonzero if the last use of REG | |
6183 | is in an insn following INSN in the same basic block. */ | |
6184 | ||
6185 | static int | |
6186 | last_use_this_basic_block (reg, insn) | |
6187 | rtx reg; | |
6188 | rtx insn; | |
6189 | { | |
6190 | rtx n; | |
6191 | for (n = insn; | |
6192 | n && GET_CODE (n) != CODE_LABEL && GET_CODE (n) != JUMP_INSN; | |
6193 | n = NEXT_INSN (n)) | |
6194 | { | |
6195 | if (regno_last_uid[REGNO (reg)] == INSN_UID (n)) | |
6196 | return 1; | |
6197 | } | |
6198 | return 0; | |
6199 | } | |
6200 | \f | |
6201 | /* Called via `note_stores' to record the initial value of a biv. Here we | |
6202 | just record the location of the set and process it later. */ | |
6203 | ||
6204 | static void | |
6205 | record_initial (dest, set) | |
6206 | rtx dest; | |
6207 | rtx set; | |
6208 | { | |
6209 | struct iv_class *bl; | |
6210 | ||
6211 | if (GET_CODE (dest) != REG | |
6212 | || REGNO (dest) >= max_reg_before_loop | |
2a5f595d PR |
6213 | || reg_iv_type[REGNO (dest)] != BASIC_INDUCT |
6214 | /* Reject this insn if the source isn't valid for the mode of DEST. */ | |
6215 | || GET_MODE (dest) != GET_MODE (SET_DEST (set))) | |
9bf86ebb PR |
6216 | return; |
6217 | ||
6218 | bl = reg_biv_class[REGNO (dest)]; | |
6219 | ||
6220 | /* If this is the first set found, record it. */ | |
6221 | if (bl->init_insn == 0) | |
6222 | { | |
6223 | bl->init_insn = note_insn; | |
6224 | bl->init_set = set; | |
6225 | } | |
6226 | } | |
6227 | \f | |
6228 | /* If any of the registers in X are "old" and currently have a last use earlier | |
6229 | than INSN, update them to have a last use of INSN. Their actual last use | |
6230 | will be the previous insn but it will not have a valid uid_luid so we can't | |
6231 | use it. */ | |
6232 | ||
6233 | static void | |
6234 | update_reg_last_use (x, insn) | |
6235 | rtx x; | |
6236 | rtx insn; | |
6237 | { | |
6238 | /* Check for the case where INSN does not have a valid luid. In this case, | |
6239 | there is no need to modify the regno_last_uid, as this can only happen | |
6240 | when code is inserted after the loop_end to set a pseudo's final value, | |
6241 | and hence this insn will never be the last use of x. */ | |
6242 | if (GET_CODE (x) == REG && REGNO (x) < max_reg_before_loop | |
6243 | && INSN_UID (insn) < max_uid_for_loop | |
6244 | && uid_luid[regno_last_uid[REGNO (x)]] < uid_luid[INSN_UID (insn)]) | |
6245 | regno_last_uid[REGNO (x)] = INSN_UID (insn); | |
6246 | else | |
6247 | { | |
6248 | register int i, j; | |
6249 | register char *fmt = GET_RTX_FORMAT (GET_CODE (x)); | |
6250 | for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--) | |
6251 | { | |
6252 | if (fmt[i] == 'e') | |
6253 | update_reg_last_use (XEXP (x, i), insn); | |
6254 | else if (fmt[i] == 'E') | |
6255 | for (j = XVECLEN (x, i) - 1; j >= 0; j--) | |
6256 | update_reg_last_use (XVECEXP (x, i, j), insn); | |
6257 | } | |
6258 | } | |
6259 | } | |
6260 | \f | |
6261 | /* Given a jump insn JUMP, return the condition that will cause it to branch | |
6262 | to its JUMP_LABEL. If the condition cannot be understood, or is an | |
6263 | inequality floating-point comparison which needs to be reversed, 0 will | |
6264 | be returned. | |
6265 | ||
6266 | If EARLIEST is non-zero, it is a pointer to a place where the earliest | |
6267 | insn used in locating the condition was found. If a replacement test | |
6268 | of the condition is desired, it should be placed in front of that | |
6269 | insn and we will be sure that the inputs are still valid. | |
6270 | ||
6271 | The condition will be returned in a canonical form to simplify testing by | |
6272 | callers. Specifically: | |
6273 | ||
6274 | (1) The code will always be a comparison operation (EQ, NE, GT, etc.). | |
6275 | (2) Both operands will be machine operands; (cc0) will have been replaced. | |
6276 | (3) If an operand is a constant, it will be the second operand. | |
6277 | (4) (LE x const) will be replaced with (LT x <const+1>) and similarly | |
6278 | for GE, GEU, and LEU. */ | |
6279 | ||
6280 | rtx | |
6281 | get_condition (jump, earliest) | |
6282 | rtx jump; | |
6283 | rtx *earliest; | |
6284 | { | |
6285 | enum rtx_code code; | |
6286 | rtx prev = jump; | |
6287 | rtx set; | |
6288 | rtx tem; | |
6289 | rtx op0, op1; | |
6290 | int reverse_code = 0; | |
6291 | int did_reverse_condition = 0; | |
6292 | ||
6293 | /* If this is not a standard conditional jump, we can't parse it. */ | |
6294 | if (GET_CODE (jump) != JUMP_INSN | |
6295 | || ! condjump_p (jump) || simplejump_p (jump)) | |
6296 | return 0; | |
6297 | ||
6298 | code = GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 0)); | |
6299 | op0 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 0); | |
6300 | op1 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 1); | |
6301 | ||
6302 | if (earliest) | |
6303 | *earliest = jump; | |
6304 | ||
6305 | /* If this branches to JUMP_LABEL when the condition is false, reverse | |
6306 | the condition. */ | |
6307 | if (GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 2)) == LABEL_REF | |
6308 | && XEXP (XEXP (SET_SRC (PATTERN (jump)), 2), 0) == JUMP_LABEL (jump)) | |
6309 | code = reverse_condition (code), did_reverse_condition ^= 1; | |
6310 | ||
6311 | /* If we are comparing a register with zero, see if the register is set | |
6312 | in the previous insn to a COMPARE or a comparison operation. Perform | |
6313 | the same tests as a function of STORE_FLAG_VALUE as find_comparison_args | |
6314 | in cse.c */ | |
6315 | ||
6316 | while (GET_RTX_CLASS (code) == '<' && op1 == const0_rtx) | |
6317 | { | |
6318 | /* Set non-zero when we find something of interest. */ | |
6319 | rtx x = 0; | |
6320 | ||
6321 | #ifdef HAVE_cc0 | |
6322 | /* If comparison with cc0, import actual comparison from compare | |
6323 | insn. */ | |
6324 | if (op0 == cc0_rtx) | |
6325 | { | |
6326 | if ((prev = prev_nonnote_insn (prev)) == 0 | |
6327 | || GET_CODE (prev) != INSN | |
6328 | || (set = single_set (prev)) == 0 | |
6329 | || SET_DEST (set) != cc0_rtx) | |
6330 | return 0; | |
6331 | ||
6332 | op0 = SET_SRC (set); | |
6333 | op1 = CONST0_RTX (GET_MODE (op0)); | |
6334 | if (earliest) | |
6335 | *earliest = prev; | |
6336 | } | |
6337 | #endif | |
6338 | ||
6339 | /* If this is a COMPARE, pick up the two things being compared. */ | |
6340 | if (GET_CODE (op0) == COMPARE) | |
6341 | { | |
6342 | op1 = XEXP (op0, 1); | |
6343 | op0 = XEXP (op0, 0); | |
6344 | continue; | |
6345 | } | |
6346 | else if (GET_CODE (op0) != REG) | |
6347 | break; | |
6348 | ||
6349 | /* Go back to the previous insn. Stop if it is not an INSN. We also | |
6350 | stop if it isn't a single set or if it has a REG_INC note because | |
6351 | we don't want to bother dealing with it. */ | |
6352 | ||
6353 | if ((prev = prev_nonnote_insn (prev)) == 0 | |
6354 | || GET_CODE (prev) != INSN | |
6355 | || FIND_REG_INC_NOTE (prev, 0) | |
6356 | || (set = single_set (prev)) == 0) | |
6357 | break; | |
6358 | ||
6359 | /* If this is setting OP0, get what it sets it to if it looks | |
6360 | relevant. */ | |
6361 | if (SET_DEST (set) == op0) | |
6362 | { | |
6363 | enum machine_mode inner_mode = GET_MODE (SET_SRC (set)); | |
6364 | ||
6365 | if ((GET_CODE (SET_SRC (set)) == COMPARE | |
6366 | || (((code == NE | |
6367 | || (code == LT | |
6368 | && GET_MODE_CLASS (inner_mode) == MODE_INT | |
6369 | && (GET_MODE_BITSIZE (inner_mode) | |
6370 | <= HOST_BITS_PER_WIDE_INT) | |
6371 | && (STORE_FLAG_VALUE | |
6372 | & ((HOST_WIDE_INT) 1 | |
6373 | << (GET_MODE_BITSIZE (inner_mode) - 1)))) | |
6374 | #ifdef FLOAT_STORE_FLAG_VALUE | |
6375 | || (code == LT | |
6376 | && GET_MODE_CLASS (inner_mode) == MODE_FLOAT | |
6377 | && FLOAT_STORE_FLAG_VALUE < 0) | |
6378 | #endif | |
6379 | )) | |
6380 | && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<'))) | |
6381 | x = SET_SRC (set); | |
6382 | else if (((code == EQ | |
6383 | || (code == GE | |
6384 | && (GET_MODE_BITSIZE (inner_mode) | |
6385 | <= HOST_BITS_PER_WIDE_INT) | |
6386 | && GET_MODE_CLASS (inner_mode) == MODE_INT | |
6387 | && (STORE_FLAG_VALUE | |
6388 | & ((HOST_WIDE_INT) 1 | |
6389 | << (GET_MODE_BITSIZE (inner_mode) - 1)))) | |
6390 | #ifdef FLOAT_STORE_FLAG_VALUE | |
6391 | || (code == GE | |
6392 | && GET_MODE_CLASS (inner_mode) == MODE_FLOAT | |
6393 | && FLOAT_STORE_FLAG_VALUE < 0) | |
6394 | #endif | |
6395 | )) | |
6396 | && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<') | |
6397 | { | |
6398 | /* We might have reversed a LT to get a GE here. But this wasn't | |
6399 | actually the comparison of data, so we don't flag that we | |
6400 | have had to reverse the condition. */ | |
6401 | did_reverse_condition ^= 1; | |
6402 | reverse_code = 1; | |
6403 | x = SET_SRC (set); | |
6404 | } | |
6405 | } | |
6406 | ||
6407 | else if (reg_set_p (op0, prev)) | |
6408 | /* If this sets OP0, but not directly, we have to give up. */ | |
6409 | break; | |
6410 | ||
6411 | if (x) | |
6412 | { | |
6413 | if (GET_RTX_CLASS (GET_CODE (x)) == '<') | |
6414 | code = GET_CODE (x); | |
6415 | if (reverse_code) | |
6416 | { | |
6417 | code = reverse_condition (code); | |
6418 | did_reverse_condition ^= 1; | |
6419 | reverse_code = 0; | |
6420 | } | |
6421 | ||
6422 | op0 = XEXP (x, 0), op1 = XEXP (x, 1); | |
6423 | if (earliest) | |
6424 | *earliest = prev; | |
6425 | } | |
6426 | } | |
6427 | ||
6428 | /* If constant is first, put it last. */ | |
6429 | if (CONSTANT_P (op0)) | |
6430 | code = swap_condition (code), tem = op0, op0 = op1, op1 = tem; | |
6431 | ||
6432 | /* If OP0 is the result of a comparison, we weren't able to find what | |
6433 | was really being compared, so fail. */ | |
6434 | if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC) | |
6435 | return 0; | |
6436 | ||
6437 | /* Canonicalize any ordered comparison with integers involving equality | |
6438 | if we can do computations in the relevant mode and we do not | |
6439 | overflow. */ | |
6440 | ||
6441 | if (GET_CODE (op1) == CONST_INT | |
6442 | && GET_MODE (op0) != VOIDmode | |
6443 | && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT) | |
6444 | { | |
6445 | HOST_WIDE_INT const_val = INTVAL (op1); | |
6446 | unsigned HOST_WIDE_INT uconst_val = const_val; | |
6447 | unsigned HOST_WIDE_INT max_val | |
6448 | = (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0)); | |
6449 | ||
6450 | switch (code) | |
6451 | { | |
6452 | case LE: | |
6453 | if (const_val != max_val >> 1) | |
6454 | code = LT, op1 = GEN_INT (const_val + 1); | |
6455 | break; | |
6456 | ||
6457 | case GE: | |
6458 | if (const_val | |
6459 | != (((HOST_WIDE_INT) 1 | |
6460 | << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1)))) | |
6461 | code = GT, op1 = GEN_INT (const_val - 1); | |
6462 | break; | |
6463 | ||
6464 | case LEU: | |
6465 | if (uconst_val != max_val) | |
6466 | code = LTU, op1 = GEN_INT (uconst_val + 1); | |
6467 | break; | |
6468 | ||
6469 | case GEU: | |
6470 | if (uconst_val != 0) | |
6471 | code = GTU, op1 = GEN_INT (uconst_val - 1); | |
6472 | break; | |
6473 | } | |
6474 | } | |
6475 | ||
6476 | /* If this was floating-point and we reversed anything other than an | |
6477 | EQ or NE, return zero. */ | |
6478 | if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT | |
6479 | && did_reverse_condition && code != NE && code != EQ | |
6480 | && GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT) | |
6481 | return 0; | |
6482 | ||
6483 | #ifdef HAVE_cc0 | |
6484 | /* Never return CC0; return zero instead. */ | |
6485 | if (op0 == cc0_rtx) | |
6486 | return 0; | |
6487 | #endif | |
6488 | ||
6489 | return gen_rtx (code, VOIDmode, op0, op1); | |
6490 | } | |
6491 | ||
6492 | /* Similar to above routine, except that we also put an invariant last | |
6493 | unless both operands are invariants. */ | |
6494 | ||
6495 | rtx | |
6496 | get_condition_for_loop (x) | |
6497 | rtx x; | |
6498 | { | |
6499 | rtx comparison = get_condition (x, NULL_PTR); | |
6500 | ||
6501 | if (comparison == 0 | |
6502 | || ! invariant_p (XEXP (comparison, 0)) | |
6503 | || invariant_p (XEXP (comparison, 1))) | |
6504 | return comparison; | |
6505 | ||
6506 | return gen_rtx (swap_condition (GET_CODE (comparison)), VOIDmode, | |
6507 | XEXP (comparison, 1), XEXP (comparison, 0)); | |
6508 | } |