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67f2de41 RK |
1 | /* Try to unroll loops, and split induction variables. |
2 | Copyright (C) 1992 Free Software Foundation, Inc. | |
3 | Contributed by James E. Wilson, Cygnus Support/UC Berkeley. | |
4 | ||
5 | This file is part of GNU CC. | |
6 | ||
7 | GNU CC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GNU CC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GNU CC; see the file COPYING. If not, write to | |
19 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
20 | ||
21 | /* Try to unroll a loop, and split induction variables. | |
22 | ||
23 | Loops for which the number of iterations can be calculated exactly are | |
24 | handled specially. If the number of iterations times the insn_count is | |
25 | less than MAX_UNROLLED_INSNS, then the loop is unrolled completely. | |
26 | Otherwise, we try to unroll the loop a number of times modulo the number | |
27 | of iterations, so that only one exit test will be needed. It is unrolled | |
28 | a number of times approximately equal to MAX_UNROLLED_INSNS divided by | |
29 | the insn count. | |
30 | ||
31 | Otherwise, if the number of iterations can be calculated exactly at | |
32 | run time, and the loop is always entered at the top, then we try to | |
33 | precondition the loop. That is, at run time, calculate how many times | |
34 | the loop will execute, and then execute the loop body a few times so | |
35 | that the remaining iterations will be some multiple of 4 (or 2 if the | |
36 | loop is large). Then fall through to a loop unrolled 4 (or 2) times, | |
37 | with only one exit test needed at the end of the loop. | |
38 | ||
39 | Otherwise, if the number of iterations can not be calculated exactly, | |
40 | not even at run time, then we still unroll the loop a number of times | |
41 | approximately equal to MAX_UNROLLED_INSNS divided by the insn count, | |
42 | but there must be an exit test after each copy of the loop body. | |
43 | ||
44 | For each induction variable, which is dead outside the loop (replaceable) | |
45 | or for which we can easily calculate the final value, if we can easily | |
46 | calculate its value at each place where it is set as a function of the | |
47 | current loop unroll count and the variable's value at loop entry, then | |
48 | the induction variable is split into `N' different variables, one for | |
49 | each copy of the loop body. One variable is live across the backward | |
50 | branch, and the others are all calculated as a function of this variable. | |
51 | This helps eliminate data dependencies, and leads to further opportunities | |
52 | for cse. */ | |
53 | ||
54 | /* Possible improvements follow: */ | |
55 | ||
56 | /* ??? Add an extra pass somewhere to determine whether unrolling will | |
57 | give any benefit. E.g. after generating all unrolled insns, compute the | |
58 | cost of all insns and compare against cost of insns in rolled loop. | |
59 | ||
60 | - On traditional architectures, unrolling a non-constant bound loop | |
61 | is a win if there is a giv whose only use is in memory addresses, the | |
62 | memory addresses can be split, and hence giv incremenets can be | |
63 | eliminated. | |
64 | - It is also a win if the loop is executed many times, and preconditioning | |
65 | can be performed for the loop. | |
66 | Add code to check for these and similar cases. */ | |
67 | ||
68 | /* ??? Improve control of which loops get unrolled. Could use profiling | |
69 | info to only unroll the most commonly executed loops. Perhaps have | |
70 | a user specifyable option to control the amount of code expansion, | |
71 | or the percent of loops to consider for unrolling. Etc. */ | |
72 | ||
73 | /* ??? Look at the register copies inside the loop to see if they form a | |
74 | simple permutation. If so, iterate the permutation until it gets back to | |
75 | the start state. This is how many times we should unroll the loop, for | |
76 | best results, because then all register copies can be eliminated. | |
77 | For example, the lisp nreverse function should be unrolled 3 times | |
78 | while (this) | |
79 | { | |
80 | next = this->cdr; | |
81 | this->cdr = prev; | |
82 | prev = this; | |
83 | this = next; | |
84 | } | |
85 | ||
86 | ??? The number of times to unroll the loop may also be based on data | |
87 | references in the loop. For example, if we have a loop that references | |
88 | x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */ | |
89 | ||
90 | /* ??? Add some simple linear equation solving capability so that we can | |
91 | determine the number of loop iterations for more complex loops. | |
92 | For example, consider this loop from gdb | |
93 | #define SWAP_TARGET_AND_HOST(buffer,len) | |
94 | { | |
95 | char tmp; | |
96 | char *p = (char *) buffer; | |
97 | char *q = ((char *) buffer) + len - 1; | |
98 | int iterations = (len + 1) >> 1; | |
99 | int i; | |
100 | for (p; p < q; p++, q--;) | |
101 | { | |
102 | tmp = *q; | |
103 | *q = *p; | |
104 | *p = tmp; | |
105 | } | |
106 | } | |
107 | Note that: | |
108 | start value = p = &buffer + current_iteration | |
109 | end value = q = &buffer + len - 1 - current_iteration | |
110 | Given the loop exit test of "p < q", then there must be "q - p" iterations, | |
111 | set equal to zero and solve for number of iterations: | |
112 | q - p = len - 1 - 2*current_iteration = 0 | |
113 | current_iteration = (len - 1) / 2 | |
114 | Hence, there are (len - 1) / 2 (rounded up to the nearest integer) | |
115 | iterations of this loop. */ | |
116 | ||
117 | /* ??? Currently, no labels are marked as loop invariant when doing loop | |
118 | unrolling. This is because an insn inside the loop, that loads the address | |
119 | of a label inside the loop into a register, could be moved outside the loop | |
120 | by the invariant code motion pass if labels were invariant. If the loop | |
121 | is subsequently unrolled, the code will be wrong because each unrolled | |
122 | body of the loop will use the same address, whereas each actually needs a | |
123 | different address. A case where this happens is when a loop containing | |
124 | a switch statement is unrolled. | |
125 | ||
126 | It would be better to let labels be considered invariant. When we | |
127 | unroll loops here, check to see if any insns using a label local to the | |
128 | loop were moved before the loop. If so, then correct the problem, by | |
129 | moving the insn back into the loop, or perhaps replicate the insn before | |
130 | the loop, one copy for each time the loop is unrolled. */ | |
131 | ||
132 | /* The prime factors looked for when trying to unroll a loop by some | |
133 | number which is modulo the total number of iterations. Just checking | |
134 | for these 4 prime factors will find at least one factor for 75% of | |
135 | all numbers theoretically. Practically speaking, this will succeed | |
136 | almost all of the time since loops are generally a multiple of 2 | |
137 | and/or 5. */ | |
138 | ||
139 | #define NUM_FACTORS 4 | |
140 | ||
141 | struct _factor { int factor, count; } factors[NUM_FACTORS] | |
142 | = { {2, 0}, {3, 0}, {5, 0}, {7, 0}}; | |
143 | ||
144 | /* Describes the different types of loop unrolling performed. */ | |
145 | ||
146 | enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE }; | |
147 | ||
148 | #include "config.h" | |
149 | #include "rtl.h" | |
150 | #include "insn-config.h" | |
151 | #include "integrate.h" | |
152 | #include "regs.h" | |
153 | #include "flags.h" | |
154 | #include "expr.h" | |
155 | #include <stdio.h> | |
156 | #include "loop.h" | |
157 | ||
158 | /* This controls which loops are unrolled, and by how much we unroll | |
159 | them. */ | |
160 | ||
161 | #ifndef MAX_UNROLLED_INSNS | |
162 | #define MAX_UNROLLED_INSNS 100 | |
163 | #endif | |
164 | ||
165 | /* Indexed by register number, if non-zero, then it contains a pointer | |
166 | to a struct induction for a DEST_REG giv which has been combined with | |
167 | one of more address givs. This is needed because whenever such a DEST_REG | |
168 | giv is modified, we must modify the value of all split address givs | |
169 | that were combined with this DEST_REG giv. */ | |
170 | ||
171 | static struct induction **addr_combined_regs; | |
172 | ||
173 | /* Indexed by register number, if this is a splittable induction variable, | |
174 | then this will hold the current value of the register, which depends on the | |
175 | iteration number. */ | |
176 | ||
177 | static rtx *splittable_regs; | |
178 | ||
179 | /* Indexed by register number, if this is a splittable induction variable, | |
180 | then this will hold the number of instructions in the loop that modify | |
181 | the induction variable. Used to ensure that only the last insn modifying | |
182 | a split iv will update the original iv of the dest. */ | |
183 | ||
184 | static int *splittable_regs_updates; | |
185 | ||
186 | /* Values describing the current loop's iteration variable. These are set up | |
187 | by loop_iterations, and used by precondition_loop_p. */ | |
188 | ||
189 | static rtx loop_iteration_var; | |
190 | static rtx loop_initial_value; | |
191 | static rtx loop_increment; | |
192 | static rtx loop_final_value; | |
193 | ||
194 | /* Forward declarations. */ | |
195 | ||
196 | static void init_reg_map (); | |
197 | static int precondition_loop_p (); | |
198 | static void copy_loop_body (); | |
199 | static void iteration_info (); | |
200 | static rtx approx_final_value (); | |
201 | static int find_splittable_regs (); | |
202 | static int find_splittable_givs (); | |
203 | static rtx fold_rtx_mult_add (); | |
204 | ||
205 | /* Try to unroll one loop and split induction variables in the loop. | |
206 | ||
207 | The loop is described by the arguments LOOP_END, INSN_COUNT, and | |
208 | LOOP_START. END_INSERT_BEDFORE indicates where insns should be added | |
209 | which need to be executed when the loop falls through. STRENGTH_REDUCTION_P | |
210 | indicates whether information generated in the strength reduction pass | |
211 | is available. | |
212 | ||
213 | This function is intended to be called from within `strength_reduce' | |
214 | in loop.c. */ | |
215 | ||
216 | void | |
217 | unroll_loop (loop_end, insn_count, loop_start, end_insert_before, | |
218 | strength_reduce_p) | |
219 | rtx loop_end; | |
220 | int insn_count; | |
221 | rtx loop_start; | |
222 | rtx end_insert_before; | |
223 | int strength_reduce_p; | |
224 | { | |
225 | int i, j, temp; | |
226 | int unroll_number = 1; | |
227 | rtx copy_start, copy_end; | |
228 | rtx insn, copy, sequence, pattern, tem; | |
229 | int max_labelno, max_insnno; | |
230 | rtx insert_before; | |
231 | struct inline_remap *map; | |
232 | char *local_label; | |
233 | int maxregnum; | |
234 | int new_maxregnum; | |
235 | rtx exit_label = 0; | |
236 | rtx start_label; | |
237 | struct iv_class *bl; | |
238 | struct induction *v; | |
239 | int splitting_not_safe = 0; | |
240 | enum unroll_types unroll_type; | |
241 | int loop_preconditioned = 0; | |
242 | rtx safety_label; | |
243 | /* This points to the last real insn in the loop, which should be either | |
244 | a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional | |
245 | jumps). */ | |
246 | rtx last_loop_insn; | |
247 | ||
248 | /* Don't bother unrolling huge loops. Since the minimum factor is | |
249 | two, loops greater than one half of MAX_UNROLLED_INSNS will never | |
250 | be unrolled. */ | |
251 | if (insn_count > MAX_UNROLLED_INSNS / 2) | |
252 | { | |
253 | if (loop_dump_stream) | |
254 | fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n"); | |
255 | return; | |
256 | } | |
257 | ||
258 | /* When emitting debugger info, we can't unroll loops with unequal numbers | |
259 | of block_beg and block_end notes, because that would unbalance the block | |
260 | structure of the function. This can happen as a result of the | |
261 | "if (foo) bar; else break;" optimization in jump.c. */ | |
262 | ||
263 | if (write_symbols != NO_DEBUG) | |
264 | { | |
265 | int block_begins = 0; | |
266 | int block_ends = 0; | |
267 | ||
268 | for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn)) | |
269 | { | |
270 | if (GET_CODE (insn) == NOTE) | |
271 | { | |
272 | if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG) | |
273 | block_begins++; | |
274 | else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END) | |
275 | block_ends++; | |
276 | } | |
277 | } | |
278 | ||
279 | if (block_begins != block_ends) | |
280 | { | |
281 | if (loop_dump_stream) | |
282 | fprintf (loop_dump_stream, | |
283 | "Unrolling failure: Unbalanced block notes.\n"); | |
284 | return; | |
285 | } | |
286 | } | |
287 | ||
288 | /* Determine type of unroll to perform. Depends on the number of iterations | |
289 | and the size of the loop. */ | |
290 | ||
291 | /* If there is no strength reduce info, then set loop_n_iterations to zero. | |
292 | This can happen if strength_reduce can't find any bivs in the loop. | |
293 | A value of zero indicates that the number of iterations could not be | |
294 | calculated. */ | |
295 | ||
296 | if (! strength_reduce_p) | |
297 | loop_n_iterations = 0; | |
298 | ||
299 | if (loop_dump_stream && loop_n_iterations > 0) | |
300 | fprintf (loop_dump_stream, | |
301 | "Loop unrolling: %d iterations.\n", loop_n_iterations); | |
302 | ||
303 | /* Find and save a pointer to the last nonnote insn in the loop. */ | |
304 | ||
305 | last_loop_insn = prev_nonnote_insn (loop_end); | |
306 | ||
307 | /* Calculate how many times to unroll the loop. Indicate whether or | |
308 | not the loop is being completely unrolled. */ | |
309 | ||
310 | if (loop_n_iterations == 1) | |
311 | { | |
312 | /* If number of iterations is exactly 1, then eliminate the compare and | |
313 | branch at the end of the loop since they will never be taken. | |
314 | Then return, since no other action is needed here. */ | |
315 | ||
316 | /* If the last instruction is not a BARRIER or a JUMP_INSN, then | |
317 | don't do anything. */ | |
318 | ||
319 | if (GET_CODE (last_loop_insn) == BARRIER) | |
320 | { | |
321 | /* Delete the jump insn. This will delete the barrier also. */ | |
322 | delete_insn (PREV_INSN (last_loop_insn)); | |
323 | } | |
324 | else if (GET_CODE (last_loop_insn) == JUMP_INSN) | |
325 | { | |
326 | #ifdef HAVE_cc0 | |
327 | /* The immediately preceeding insn is a compare which must be | |
328 | deleted. */ | |
329 | delete_insn (last_loop_insn); | |
330 | delete_insn (PREV_INSN (last_loop_insn)); | |
331 | #else | |
332 | /* The immediately preceeding insn may not be the compare, so don't | |
333 | delete it. */ | |
334 | delete_insn (last_loop_insn); | |
335 | #endif | |
336 | } | |
337 | return; | |
338 | } | |
339 | else if (loop_n_iterations > 0 | |
340 | && loop_n_iterations * insn_count < MAX_UNROLLED_INSNS) | |
341 | { | |
342 | unroll_number = loop_n_iterations; | |
343 | unroll_type = UNROLL_COMPLETELY; | |
344 | } | |
345 | else if (loop_n_iterations > 0) | |
346 | { | |
347 | /* Try to factor the number of iterations. Don't bother with the | |
348 | general case, only using 2, 3, 5, and 7 will get 75% of all | |
349 | numbers theoretically, and almost all in practice. */ | |
350 | ||
351 | for (i = 0; i < NUM_FACTORS; i++) | |
352 | factors[i].count = 0; | |
353 | ||
354 | temp = loop_n_iterations; | |
355 | for (i = NUM_FACTORS - 1; i >= 0; i--) | |
356 | while (temp % factors[i].factor == 0) | |
357 | { | |
358 | factors[i].count++; | |
359 | temp = temp / factors[i].factor; | |
360 | } | |
361 | ||
362 | /* Start with the larger factors first so that we generally | |
363 | get lots of unrolling. */ | |
364 | ||
365 | unroll_number = 1; | |
366 | temp = insn_count; | |
367 | for (i = 3; i >= 0; i--) | |
368 | while (factors[i].count--) | |
369 | { | |
370 | if (temp * factors[i].factor < MAX_UNROLLED_INSNS) | |
371 | { | |
372 | unroll_number *= factors[i].factor; | |
373 | temp *= factors[i].factor; | |
374 | } | |
375 | else | |
376 | break; | |
377 | } | |
378 | ||
379 | /* If we couldn't find any factors, then unroll as in the normal | |
380 | case. */ | |
381 | if (unroll_number == 1) | |
382 | { | |
383 | if (loop_dump_stream) | |
384 | fprintf (loop_dump_stream, | |
385 | "Loop unrolling: No factors found.\n"); | |
386 | } | |
387 | else | |
388 | unroll_type = UNROLL_MODULO; | |
389 | } | |
390 | ||
391 | ||
392 | /* Default case, calculate number of times to unroll loop based on its | |
393 | size. */ | |
394 | if (unroll_number == 1) | |
395 | { | |
396 | if (8 * insn_count < MAX_UNROLLED_INSNS) | |
397 | unroll_number = 8; | |
398 | else if (4 * insn_count < MAX_UNROLLED_INSNS) | |
399 | unroll_number = 4; | |
400 | else | |
401 | unroll_number = 2; | |
402 | ||
403 | unroll_type = UNROLL_NAIVE; | |
404 | } | |
405 | ||
406 | /* Now we know how many times to unroll the loop. */ | |
407 | ||
408 | if (loop_dump_stream) | |
409 | fprintf (loop_dump_stream, | |
410 | "Unrolling loop %d times.\n", unroll_number); | |
411 | ||
412 | ||
413 | if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO) | |
414 | { | |
415 | /* Loops of these types should never start with a jump down to | |
416 | the exit condition test. For now, check for this case just to | |
417 | be sure. UNROLL_NAIVE loops can be of this form, this case is | |
418 | handled below. */ | |
419 | insn = loop_start; | |
420 | while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN) | |
421 | insn = NEXT_INSN (insn); | |
422 | if (GET_CODE (insn) == JUMP_INSN) | |
423 | abort (); | |
424 | } | |
425 | ||
426 | if (unroll_type == UNROLL_COMPLETELY) | |
427 | { | |
428 | /* Completely unrolling the loop: Delete the compare and branch at | |
429 | the end (the last two instructions). This delete must done at the | |
430 | very end of loop unrolling, to avoid problems with calls to | |
431 | back_branch_in_range_p, which is called by find_splittable_regs. | |
432 | All increments of splittable bivs/givs are changed to load constant | |
433 | instructions. */ | |
434 | ||
435 | copy_start = loop_start; | |
436 | ||
437 | /* Set insert_before to the instruction immediately after the JUMP_INSN | |
438 | (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of | |
439 | the loop will be correctly handled by copy_loop_body. */ | |
440 | insert_before = NEXT_INSN (last_loop_insn); | |
441 | ||
442 | /* Set copy_end to the insn before the jump at the end of the loop. */ | |
443 | if (GET_CODE (last_loop_insn) == BARRIER) | |
444 | copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); | |
445 | else if (GET_CODE (last_loop_insn) == JUMP_INSN) | |
446 | { | |
447 | #ifdef HAVE_cc0 | |
448 | /* The instruction immediately before the JUMP_INSN is a compare | |
449 | instruction which we do not want to copy. */ | |
450 | copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); | |
451 | #else | |
452 | /* The instruction immediately before the JUMP_INSN may not be the | |
453 | compare, so we must copy it. */ | |
454 | copy_end = PREV_INSN (last_loop_insn); | |
455 | #endif | |
456 | } | |
457 | else | |
458 | { | |
459 | /* We currently can't unroll a loop if it doesn't end with a | |
460 | JUMP_INSN. There would need to be a mechanism that recognizes | |
461 | this case, and then inserts a jump after each loop body, which | |
462 | jumps to after the last loop body. */ | |
463 | if (loop_dump_stream) | |
464 | fprintf (loop_dump_stream, | |
465 | "Unrolling failure: loop does not end with a JUMP_INSN.\n"); | |
466 | return; | |
467 | } | |
468 | } | |
469 | else if (unroll_type == UNROLL_MODULO) | |
470 | { | |
471 | /* Partially unrolling the loop: The compare and branch at the end | |
472 | (the last two instructions) must remain. Don't copy the compare | |
473 | and branch instructions at the end of the loop. Insert the unrolled | |
474 | code immediately before the compare/branch at the end so that the | |
475 | code will fall through to them as before. */ | |
476 | ||
477 | copy_start = loop_start; | |
478 | ||
479 | /* Set insert_before to the jump insn at the end of the loop. | |
480 | Set copy_end to before the jump insn at the end of the loop. */ | |
481 | if (GET_CODE (last_loop_insn) == BARRIER) | |
482 | { | |
483 | insert_before = PREV_INSN (last_loop_insn); | |
484 | copy_end = PREV_INSN (insert_before); | |
485 | } | |
486 | else if (GET_CODE (last_loop_insn) == JUMP_INSN) | |
487 | { | |
488 | #ifdef HAVE_cc0 | |
489 | /* The instruction immediately before the JUMP_INSN is a compare | |
490 | instruction which we do not want to copy or delete. */ | |
491 | insert_before = PREV_INSN (last_loop_insn); | |
492 | copy_end = PREV_INSN (insert_before); | |
493 | #else | |
494 | /* The instruction immediately before the JUMP_INSN may not be the | |
495 | compare, so we must copy it. */ | |
496 | insert_before = last_loop_insn; | |
497 | copy_end = PREV_INSN (last_loop_insn); | |
498 | #endif | |
499 | } | |
500 | else | |
501 | { | |
502 | /* We currently can't unroll a loop if it doesn't end with a | |
503 | JUMP_INSN. There would need to be a mechanism that recognizes | |
504 | this case, and then inserts a jump after each loop body, which | |
505 | jumps to after the last loop body. */ | |
506 | if (loop_dump_stream) | |
507 | fprintf (loop_dump_stream, | |
508 | "Unrolling failure: loop does not end with a JUMP_INSN.\n"); | |
509 | return; | |
510 | } | |
511 | } | |
512 | else | |
513 | { | |
514 | /* Normal case: Must copy the compare and branch instructions at the | |
515 | end of the loop. */ | |
516 | ||
517 | if (GET_CODE (last_loop_insn) == BARRIER) | |
518 | { | |
519 | /* Loop ends with an unconditional jump and a barrier. | |
520 | Handle this like above, don't copy jump and barrier. | |
521 | This is not strictly necessary, but doing so prevents generating | |
522 | unconditional jumps to an immediately following label. | |
523 | ||
524 | This will be corrected below if the target of this jump is | |
525 | not the start_label. */ | |
526 | ||
527 | insert_before = PREV_INSN (last_loop_insn); | |
528 | copy_end = PREV_INSN (insert_before); | |
529 | } | |
530 | else if (GET_CODE (last_loop_insn) == JUMP_INSN) | |
531 | { | |
532 | /* Set insert_before to immediately after the JUMP_INSN, so that | |
533 | NOTEs at the end of the loop will be correctly handled by | |
534 | copy_loop_body. */ | |
535 | insert_before = NEXT_INSN (last_loop_insn); | |
536 | copy_end = last_loop_insn; | |
537 | } | |
538 | else | |
539 | { | |
540 | /* We currently can't unroll a loop if it doesn't end with a | |
541 | JUMP_INSN. There would need to be a mechanism that recognizes | |
542 | this case, and then inserts a jump after each loop body, which | |
543 | jumps to after the last loop body. */ | |
544 | if (loop_dump_stream) | |
545 | fprintf (loop_dump_stream, | |
546 | "Unrolling failure: loop does not end with a JUMP_INSN.\n"); | |
547 | return; | |
548 | } | |
549 | ||
550 | /* If copying exit test branches because they can not be eliminated, | |
551 | then must convert the fall through case of the branch to a jump past | |
552 | the end of the loop. Create a label to emit after the loop and save | |
553 | it for later use. Do not use the label after the loop, if any, since | |
554 | it might be used by insns outside the loop, or there might be insns | |
555 | added before it later by final_[bg]iv_value which must be after | |
556 | the real exit label. */ | |
557 | exit_label = gen_label_rtx (); | |
558 | ||
559 | insn = loop_start; | |
560 | while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN) | |
561 | insn = NEXT_INSN (insn); | |
562 | ||
563 | if (GET_CODE (insn) == JUMP_INSN) | |
564 | { | |
565 | /* The loop starts with a jump down to the exit condition test. | |
566 | Start copying the loop after the barrier following this | |
567 | jump insn. */ | |
568 | copy_start = NEXT_INSN (insn); | |
569 | ||
570 | /* Splitting induction variables doesn't work when the loop is | |
571 | entered via a jump to the bottom, because then we end up doing | |
572 | a comparison against a new register for a split variable, but | |
573 | we did not execute the set insn for the new register because | |
574 | it was skipped over. */ | |
575 | splitting_not_safe = 1; | |
576 | if (loop_dump_stream) | |
577 | fprintf (loop_dump_stream, | |
578 | "Splitting not safe, because loop not entered at top.\n"); | |
579 | } | |
580 | else | |
581 | copy_start = loop_start; | |
582 | } | |
583 | ||
584 | /* This should always be the first label in the loop. */ | |
585 | start_label = NEXT_INSN (copy_start); | |
586 | /* There may be a line number note and/or a loop continue note here. */ | |
587 | while (GET_CODE (start_label) == NOTE) | |
588 | start_label = NEXT_INSN (start_label); | |
589 | if (GET_CODE (start_label) != CODE_LABEL) | |
590 | { | |
591 | /* This can happen as a result of jump threading. If the first insns in | |
592 | the loop test the same condition as the loop's backward jump, or the | |
593 | opposite condition, then the backward jump will be modified to point | |
594 | to elsewhere, and the loop's start label is deleted. | |
595 | ||
596 | This case currently can not be handled by the loop unrolling code. */ | |
597 | ||
598 | if (loop_dump_stream) | |
599 | fprintf (loop_dump_stream, | |
600 | "Unrolling failure: unknown insns between BEG note and loop label.\n"); | |
601 | return; | |
602 | } | |
603 | ||
604 | if (unroll_type == UNROLL_NAIVE | |
605 | && GET_CODE (last_loop_insn) == BARRIER | |
606 | && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn))) | |
607 | { | |
608 | /* In this case, we must copy the jump and barrier, because they will | |
609 | not be converted to jumps to an immediately following label. */ | |
610 | ||
611 | insert_before = NEXT_INSN (last_loop_insn); | |
612 | copy_end = last_loop_insn; | |
613 | } | |
614 | ||
615 | /* Allocate a translation table for the labels and insn numbers. | |
616 | They will be filled in as we copy the insns in the loop. */ | |
617 | ||
618 | max_labelno = max_label_num (); | |
619 | max_insnno = get_max_uid (); | |
620 | ||
621 | map = (struct inline_remap *) alloca (sizeof (struct inline_remap)); | |
622 | ||
623 | /* Allocate the label map. */ | |
624 | ||
625 | if (max_labelno > 0) | |
626 | { | |
627 | map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx)); | |
628 | ||
629 | local_label = (char *) alloca (max_labelno); | |
630 | bzero (local_label, max_labelno); | |
631 | } | |
632 | else | |
633 | map->label_map = 0; | |
634 | ||
635 | /* Search the loop and mark all local labels, i.e. the ones which have to | |
636 | be distinct labels when copied. For all labels which might be | |
637 | non-local, set their label_map entries to point to themselves. | |
638 | If they happen to be local their label_map entries will be overwritten | |
639 | before the loop body is copied. The label_map entries for local labels | |
640 | will be set to a different value each time the loop body is copied. */ | |
641 | ||
642 | for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn)) | |
643 | { | |
644 | if (GET_CODE (insn) == CODE_LABEL) | |
645 | local_label[CODE_LABEL_NUMBER (insn)] = 1; | |
646 | else if (GET_CODE (insn) == JUMP_INSN) | |
647 | { | |
648 | if (JUMP_LABEL (insn)) | |
649 | map->label_map[CODE_LABEL_NUMBER (JUMP_LABEL (insn))] | |
650 | = JUMP_LABEL (insn); | |
651 | else if (GET_CODE (PATTERN (insn)) == ADDR_VEC | |
652 | || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC) | |
653 | { | |
654 | rtx pat = PATTERN (insn); | |
655 | int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; | |
656 | int len = XVECLEN (pat, diff_vec_p); | |
657 | rtx label; | |
658 | ||
659 | for (i = 0; i < len; i++) | |
660 | { | |
661 | label = XEXP (XVECEXP (pat, diff_vec_p, i), 0); | |
662 | map->label_map[CODE_LABEL_NUMBER (label)] = label; | |
663 | } | |
664 | } | |
665 | } | |
666 | } | |
667 | ||
668 | /* Allocate space for the insn map. */ | |
669 | ||
670 | map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx)); | |
671 | ||
672 | /* Set this to zero, to indicate that we are doing loop unrolling, | |
673 | not function inlining. */ | |
674 | map->inline_target = 0; | |
675 | ||
676 | /* The register and constant maps depend on the number of registers | |
677 | present, so the final maps can't be created until after | |
678 | find_splittable_regs is called. However, they are needed for | |
679 | preconditioning, so we create temporary maps when preconditioning | |
680 | is performed. */ | |
681 | ||
682 | /* The preconditioning code may allocate two new pseudo registers. */ | |
683 | maxregnum = max_reg_num (); | |
684 | ||
685 | /* Allocate and zero out the splittable_regs and addr_combined_regs | |
686 | arrays. These must be zeroed here because they will be used if | |
687 | loop preconditioning is performed, and must be zero for that case. | |
688 | ||
689 | It is safe to do this here, since the extra registers created by the | |
690 | preconditioning code and find_splittable_regs will never be used | |
691 | to accees the splittable_regs[] and addr_combined_regs[] arrays. */ | |
692 | ||
693 | splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx)); | |
694 | bzero (splittable_regs, maxregnum * sizeof (rtx)); | |
695 | splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int)); | |
696 | bzero (splittable_regs_updates, maxregnum * sizeof (int)); | |
697 | addr_combined_regs | |
698 | = (struct induction **) alloca (maxregnum * sizeof (struct induction *)); | |
699 | bzero (addr_combined_regs, maxregnum * sizeof (struct induction *)); | |
700 | ||
701 | /* If this loop requires exit tests when unrolled, check to see if we | |
702 | can precondition the loop so as to make the exit tests unnecessary. | |
703 | Just like variable splitting, this is not safe if the loop is entered | |
704 | via a jump to the bottom. Also, can not do this if no strength | |
705 | reduce info, because precondition_loop_p uses this info. */ | |
706 | ||
707 | /* Must copy the loop body for preconditioning before the following | |
708 | find_splittable_regs call since that will emit insns which need to | |
709 | be after the preconditioned loop copies, but immediately before the | |
710 | unrolled loop copies. */ | |
711 | ||
712 | /* Also, it is not safe to split induction variables for the preconditioned | |
713 | copies of the loop body. If we split induction variables, then the code | |
714 | assumes that each induction variable can be represented as a function | |
715 | of its initial value and the loop iteration number. This is not true | |
716 | in this case, because the last preconditioned copy of the loop body | |
717 | could be any iteration from the first up to the `unroll_number-1'th, | |
718 | depending on the initial value of the iteration variable. Therefore | |
719 | we can not split induction variables here, because we can not calculate | |
720 | their value. Hence, this code must occur before find_splittable_regs | |
721 | is called. */ | |
722 | ||
723 | if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p) | |
724 | { | |
725 | rtx initial_value, final_value, increment; | |
726 | ||
727 | if (precondition_loop_p (&initial_value, &final_value, &increment, | |
728 | loop_start, loop_end)) | |
729 | { | |
730 | register rtx diff, temp; | |
731 | enum machine_mode mode; | |
732 | rtx *labels; | |
733 | int abs_inc, neg_inc; | |
734 | ||
735 | map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx)); | |
736 | ||
737 | map->const_equiv_map = (rtx *) alloca (maxregnum * sizeof (rtx)); | |
738 | map->const_age_map = (unsigned *) alloca (maxregnum | |
739 | * sizeof (unsigned)); | |
740 | map->const_equiv_map_size = maxregnum; | |
741 | global_const_equiv_map = map->const_equiv_map; | |
742 | ||
743 | init_reg_map (map, maxregnum); | |
744 | ||
745 | /* Limit loop unrolling to 4, since this will make 7 copies of | |
746 | the loop body. */ | |
747 | if (unroll_number > 4) | |
748 | unroll_number = 4; | |
749 | ||
750 | /* Save the absolute value of the increment, and also whether or | |
751 | not it is negative. */ | |
752 | neg_inc = 0; | |
753 | abs_inc = INTVAL (increment); | |
754 | if (abs_inc < 0) | |
755 | { | |
756 | abs_inc = - abs_inc; | |
757 | neg_inc = 1; | |
758 | } | |
759 | ||
760 | start_sequence (); | |
761 | ||
762 | /* Decide what mode to do these calculations in. Choose the larger | |
763 | of final_value's mode and initial_value's mode, or a full-word if | |
764 | both are constants. */ | |
765 | mode = GET_MODE (final_value); | |
766 | if (mode == VOIDmode) | |
767 | { | |
768 | mode = GET_MODE (initial_value); | |
769 | if (mode == VOIDmode) | |
770 | mode = word_mode; | |
771 | } | |
772 | else if (mode != GET_MODE (initial_value) | |
773 | && (GET_MODE_SIZE (mode) | |
774 | < GET_MODE_SIZE (GET_MODE (initial_value)))) | |
775 | mode = GET_MODE (initial_value); | |
776 | ||
777 | /* Calculate the difference between the final and initial values. | |
778 | Final value may be a (plus (reg x) (const_int 1)) rtx. | |
779 | Let the following cse pass simplify this if initial value is | |
780 | a constant. | |
781 | ||
782 | We must copy the final and initial values here to avoid | |
783 | improperly shared rtl. */ | |
784 | ||
785 | diff = expand_binop (mode, sub_optab, copy_rtx (final_value), | |
786 | copy_rtx (initial_value), 0, 0, | |
787 | OPTAB_LIB_WIDEN); | |
788 | ||
789 | /* Now calculate (diff % (unroll * abs (increment))) by using an | |
790 | and instruction. */ | |
791 | diff = expand_binop (GET_MODE (diff), and_optab, diff, | |
792 | gen_rtx (CONST_INT, VOIDmode, | |
793 | unroll_number * abs_inc - 1), | |
794 | 0, 0, OPTAB_LIB_WIDEN); | |
795 | ||
796 | /* Now emit a sequence of branches to jump to the proper precond | |
797 | loop entry point. */ | |
798 | ||
799 | labels = (rtx *) alloca (sizeof (rtx) * unroll_number); | |
800 | for (i = 0; i < unroll_number; i++) | |
801 | labels[i] = gen_label_rtx (); | |
802 | ||
803 | /* Assuming the unroll_number is 4, and the increment is 2, then | |
804 | for a negative increment: for a positive increment: | |
805 | diff = 0,1 precond 0 diff = 0,7 precond 0 | |
806 | diff = 2,3 precond 3 diff = 1,2 precond 1 | |
807 | diff = 4,5 precond 2 diff = 3,4 precond 2 | |
808 | diff = 6,7 precond 1 diff = 5,6 precond 3 */ | |
809 | ||
810 | /* We only need to emit (unroll_number - 1) branches here, the | |
811 | last case just falls through to the following code. */ | |
812 | ||
813 | /* ??? This would give better code if we emitted a tree of branches | |
814 | instead of the current linear list of branches. */ | |
815 | ||
816 | for (i = 0; i < unroll_number - 1; i++) | |
817 | { | |
818 | int cmp_const; | |
819 | ||
820 | /* For negative increments, must invert the constant compared | |
821 | against, except when comparing against zero. */ | |
822 | if (i == 0) | |
823 | cmp_const = 0; | |
824 | else if (neg_inc) | |
825 | cmp_const = unroll_number - i; | |
826 | else | |
827 | cmp_const = i; | |
828 | ||
829 | emit_cmp_insn (diff, gen_rtx (CONST_INT, VOIDmode, | |
830 | abs_inc * cmp_const), | |
831 | EQ, 0, mode, 0, 0); | |
832 | ||
833 | if (i == 0) | |
834 | emit_jump_insn (gen_beq (labels[i])); | |
835 | else if (neg_inc) | |
836 | emit_jump_insn (gen_bge (labels[i])); | |
837 | else | |
838 | emit_jump_insn (gen_ble (labels[i])); | |
839 | JUMP_LABEL (get_last_insn ()) = labels[i]; | |
840 | LABEL_NUSES (labels[i])++; | |
841 | } | |
842 | ||
843 | /* If the increment is greater than one, then we need another branch, | |
844 | to handle other cases equivalent to 0. */ | |
845 | ||
846 | /* ??? This should be merged into the code above somehow to help | |
847 | simplify the code here, and reduce the number of branches emitted. | |
848 | For the negative increment case, the branch here could easily | |
849 | be merged with the `0' case branch above. For the positive | |
850 | increment case, it is not clear how this can be simplified. */ | |
851 | ||
852 | if (abs_inc != 1) | |
853 | { | |
854 | int cmp_const; | |
855 | ||
856 | if (neg_inc) | |
857 | cmp_const = abs_inc - 1; | |
858 | else | |
859 | cmp_const = abs_inc * (unroll_number - 1) + 1; | |
860 | ||
861 | emit_cmp_insn (diff, gen_rtx (CONST_INT, VOIDmode, cmp_const), | |
862 | EQ, 0, mode, 0, 0); | |
863 | ||
864 | if (neg_inc) | |
865 | emit_jump_insn (gen_ble (labels[0])); | |
866 | else | |
867 | emit_jump_insn (gen_bge (labels[0])); | |
868 | JUMP_LABEL (get_last_insn ()) = labels[0]; | |
869 | LABEL_NUSES (labels[0])++; | |
870 | } | |
871 | ||
872 | sequence = gen_sequence (); | |
873 | end_sequence (); | |
874 | emit_insn_before (sequence, loop_start); | |
875 | ||
876 | /* Only the last copy of the loop body here needs the exit | |
877 | test, so set copy_end to exclude the compare/branch here, | |
878 | and then reset it inside the loop when get to the last | |
879 | copy. */ | |
880 | ||
881 | if (GET_CODE (last_loop_insn) == BARRIER) | |
882 | copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); | |
883 | else if (GET_CODE (last_loop_insn) == JUMP_INSN) | |
884 | { | |
885 | #ifdef HAVE_cc0 | |
886 | /* The immediately preceeding insn is a compare which we do not | |
887 | want to copy. */ | |
888 | copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); | |
889 | #else | |
890 | /* The immediately preceeding insn may not be a compare, so we | |
891 | must copy it. */ | |
892 | copy_end = PREV_INSN (last_loop_insn); | |
893 | #endif | |
894 | } | |
895 | else | |
896 | abort (); | |
897 | ||
898 | for (i = 1; i < unroll_number; i++) | |
899 | { | |
900 | emit_label_after (labels[unroll_number - i], | |
901 | PREV_INSN (loop_start)); | |
902 | ||
903 | bzero (map->insn_map, max_insnno * sizeof (rtx)); | |
904 | bzero (map->const_equiv_map, maxregnum * sizeof (rtx)); | |
905 | bzero (map->const_age_map, maxregnum * sizeof (unsigned)); | |
906 | map->const_age = 0; | |
907 | ||
908 | for (j = 0; j < max_labelno; j++) | |
909 | if (local_label[j]) | |
910 | map->label_map[j] = gen_label_rtx (); | |
911 | ||
912 | /* The last copy needs the compare/branch insns at the end, | |
913 | so reset copy_end here if the loop ends with a conditional | |
914 | branch. */ | |
915 | ||
916 | if (i == unroll_number - 1) | |
917 | { | |
918 | if (GET_CODE (last_loop_insn) == BARRIER) | |
919 | copy_end = PREV_INSN (PREV_INSN (last_loop_insn)); | |
920 | else | |
921 | copy_end = last_loop_insn; | |
922 | } | |
923 | ||
924 | /* None of the copies are the `last_iteration', so just | |
925 | pass zero for that parameter. */ | |
926 | copy_loop_body (copy_start, copy_end, map, exit_label, 0, | |
927 | unroll_type, start_label, loop_end, | |
928 | loop_start, copy_end); | |
929 | } | |
930 | emit_label_after (labels[0], PREV_INSN (loop_start)); | |
931 | ||
932 | if (GET_CODE (last_loop_insn) == BARRIER) | |
933 | { | |
934 | insert_before = PREV_INSN (last_loop_insn); | |
935 | copy_end = PREV_INSN (insert_before); | |
936 | } | |
937 | else | |
938 | { | |
939 | #ifdef HAVE_cc0 | |
940 | /* The immediately preceeding insn is a compare which we do not | |
941 | want to copy. */ | |
942 | insert_before = PREV_INSN (last_loop_insn); | |
943 | copy_end = PREV_INSN (insert_before); | |
944 | #else | |
945 | /* The immediately preceeding insn may not be a compare, so we | |
946 | must copy it. */ | |
947 | insert_before = last_loop_insn; | |
948 | copy_end = PREV_INSN (last_loop_insn); | |
949 | #endif | |
950 | } | |
951 | ||
952 | /* Set unroll type to MODULO now. */ | |
953 | unroll_type = UNROLL_MODULO; | |
954 | loop_preconditioned = 1; | |
955 | } | |
956 | } | |
957 | ||
958 | /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll | |
959 | the loop unless all loops are being unrolled. */ | |
960 | if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops) | |
961 | { | |
962 | if (loop_dump_stream) | |
963 | fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n"); | |
964 | return; | |
965 | } | |
966 | ||
967 | /* At this point, we are guaranteed to unroll the loop. */ | |
968 | ||
969 | /* For each biv and giv, determine whether it can be safely split into | |
970 | a different variable for each unrolled copy of the loop body. | |
971 | We precalculate and save this info here, since computing it is | |
972 | expensive. | |
973 | ||
974 | Do this before deleting any instructions from the loop, so that | |
975 | back_branch_in_range_p will work correctly. */ | |
976 | ||
977 | if (splitting_not_safe) | |
978 | temp = 0; | |
979 | else | |
980 | temp = find_splittable_regs (unroll_type, loop_start, loop_end, | |
981 | end_insert_before, unroll_number); | |
982 | ||
983 | /* find_splittable_regs may have created some new registers, so must | |
984 | reallocate the reg_map with the new larger size, and must realloc | |
985 | the constant maps also. */ | |
986 | ||
987 | maxregnum = max_reg_num (); | |
988 | map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx)); | |
989 | ||
990 | init_reg_map (map, maxregnum); | |
991 | ||
992 | /* Space is needed in some of the map for new registers, so new_maxregnum | |
993 | is an (over)estimate of how many registers will exist at the end. */ | |
994 | new_maxregnum = maxregnum + (temp * unroll_number * 2); | |
995 | ||
996 | /* Must realloc space for the constant maps, because the number of registers | |
997 | may have changed. */ | |
998 | ||
999 | map->const_equiv_map = (rtx *) alloca (new_maxregnum * sizeof (rtx)); | |
1000 | map->const_age_map = (unsigned *) alloca (new_maxregnum * sizeof (unsigned)); | |
1001 | ||
1002 | global_const_equiv_map = map->const_equiv_map; | |
1003 | ||
1004 | /* Search the list of bivs and givs to find ones which need to be remapped | |
1005 | when split, and set their reg_map entry appropriately. */ | |
1006 | ||
1007 | for (bl = loop_iv_list; bl; bl = bl->next) | |
1008 | { | |
1009 | if (REGNO (bl->biv->src_reg) != bl->regno) | |
1010 | map->reg_map[bl->regno] = bl->biv->src_reg; | |
1011 | #if 0 | |
1012 | /* Currently, non-reduced/final-value givs are never split. */ | |
1013 | for (v = bl->giv; v; v = v->next_iv) | |
1014 | if (REGNO (v->src_reg) != bl->regno) | |
1015 | map->reg_map[REGNO (v->dest_reg)] = v->src_reg; | |
1016 | #endif | |
1017 | } | |
1018 | ||
1019 | /* If the loop is being partially unrolled, and the iteration variables | |
1020 | are being split, and are being renamed for the split, then must fix up | |
1021 | the compare instruction at the end of the loop to refer to the new | |
1022 | registers. This compare isn't copied, so the registers used in it | |
1023 | will never be replaced if it isn't done here. */ | |
1024 | ||
1025 | if (unroll_type == UNROLL_MODULO) | |
1026 | { | |
1027 | insn = NEXT_INSN (copy_end); | |
1028 | if (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SET) | |
1029 | { | |
1030 | #if 0 | |
1031 | /* If non-reduced/final-value givs were split, then this would also | |
1032 | have to remap those givs. */ | |
1033 | #endif | |
1034 | ||
1035 | tem = SET_SRC (PATTERN (insn)); | |
1036 | /* The set source is a register. */ | |
1037 | if (GET_CODE (tem) == REG) | |
1038 | { | |
1039 | if (REGNO (tem) < max_reg_before_loop | |
1040 | && reg_iv_type[REGNO (tem)] == BASIC_INDUCT) | |
1041 | SET_SRC (PATTERN (insn)) | |
1042 | = reg_biv_class[REGNO (tem)]->biv->src_reg; | |
1043 | } | |
1044 | else | |
1045 | { | |
1046 | /* The set source is a compare of some sort. */ | |
1047 | tem = XEXP (SET_SRC (PATTERN (insn)), 0); | |
1048 | if (GET_CODE (tem) == REG | |
1049 | && REGNO (tem) < max_reg_before_loop | |
1050 | && reg_iv_type[REGNO (tem)] == BASIC_INDUCT) | |
1051 | XEXP (SET_SRC (PATTERN (insn)), 0) | |
1052 | = reg_biv_class[REGNO (tem)]->biv->src_reg; | |
1053 | ||
1054 | tem = XEXP (SET_SRC (PATTERN (insn)), 1); | |
1055 | if (GET_CODE (tem) == REG | |
1056 | && REGNO (tem) < max_reg_before_loop | |
1057 | && reg_iv_type[REGNO (tem)] == BASIC_INDUCT) | |
1058 | XEXP (SET_SRC (PATTERN (insn)), 1) | |
1059 | = reg_biv_class[REGNO (tem)]->biv->src_reg; | |
1060 | } | |
1061 | } | |
1062 | } | |
1063 | ||
1064 | /* For unroll_number - 1 times, make a copy of each instruction | |
1065 | between copy_start and copy_end, and insert these new instructions | |
1066 | before the end of the loop. */ | |
1067 | ||
1068 | for (i = 0; i < unroll_number; i++) | |
1069 | { | |
1070 | bzero (map->insn_map, max_insnno * sizeof (rtx)); | |
1071 | bzero (map->const_equiv_map, new_maxregnum * sizeof (rtx)); | |
1072 | bzero (map->const_age_map, new_maxregnum * sizeof (unsigned)); | |
1073 | map->const_age = 0; | |
1074 | ||
1075 | for (j = 0; j < max_labelno; j++) | |
1076 | if (local_label[j]) | |
1077 | map->label_map[j] = gen_label_rtx (); | |
1078 | ||
1079 | /* If loop starts with a branch to the test, then fix it so that | |
1080 | it points to the test of the first unrolled copy of the loop. */ | |
1081 | if (i == 0 && loop_start != copy_start) | |
1082 | { | |
1083 | insn = PREV_INSN (copy_start); | |
1084 | pattern = PATTERN (insn); | |
1085 | ||
1086 | tem = map->label_map[CODE_LABEL_NUMBER | |
1087 | (XEXP (SET_SRC (pattern), 0))]; | |
1088 | SET_SRC (pattern) = gen_rtx (LABEL_REF, VOIDmode, tem); | |
1089 | ||
1090 | /* Set the jump label so that it can be used by later loop unrolling | |
1091 | passes. */ | |
1092 | JUMP_LABEL (insn) = tem; | |
1093 | LABEL_NUSES (tem)++; | |
1094 | } | |
1095 | ||
1096 | copy_loop_body (copy_start, copy_end, map, exit_label, | |
1097 | i == unroll_number - 1, unroll_type, start_label, | |
1098 | loop_end, insert_before, insert_before); | |
1099 | } | |
1100 | ||
1101 | /* Before deleting any insns, emit a CODE_LABEL immediately after the last | |
1102 | insn to be deleted. This prevents any runaway delete_insn call from | |
1103 | more insns that it should, as it always stops at a CODE_LABEL. */ | |
1104 | ||
1105 | /* Delete the compare and branch at the end of the loop if completely | |
1106 | unrolling the loop. Deleting the backward branch at the end also | |
1107 | deletes the code label at the start of the loop. This is done at | |
1108 | the very end to avoid problems with back_branch_in_range_p. */ | |
1109 | ||
1110 | if (unroll_type == UNROLL_COMPLETELY) | |
1111 | safety_label = emit_label_after (gen_label_rtx (), last_loop_insn); | |
1112 | else | |
1113 | safety_label = emit_label_after (gen_label_rtx (), copy_end); | |
1114 | ||
1115 | /* Delete all of the original loop instructions. Don't delete the | |
1116 | LOOP_BEG note, or the first code label in the loop. */ | |
1117 | ||
1118 | insn = NEXT_INSN (copy_start); | |
1119 | while (insn != safety_label) | |
1120 | { | |
1121 | if (insn != start_label) | |
1122 | insn = delete_insn (insn); | |
1123 | else | |
1124 | insn = NEXT_INSN (insn); | |
1125 | } | |
1126 | ||
1127 | /* Can now delete the 'safety' label emitted to protect us from runaway | |
1128 | delete_insn calls. */ | |
1129 | if (INSN_DELETED_P (safety_label)) | |
1130 | abort (); | |
1131 | delete_insn (safety_label); | |
1132 | ||
1133 | /* If exit_label exists, emit it after the loop. Doing the emit here | |
1134 | forces it to have a higher INSN_UID than any insn in the unrolled loop. | |
1135 | This is needed so that mostly_true_jump in reorg.c will treat jumps | |
1136 | to this loop end label correctly, i.e. predict that they are usually | |
1137 | not taken. */ | |
1138 | if (exit_label) | |
1139 | emit_label_after (exit_label, loop_end); | |
1140 | ||
1141 | /* If debugging, we must replicate the tree nodes corresponsing to the blocks | |
1142 | inside the loop, so that the original one to one mapping will remain. */ | |
1143 | ||
1144 | if (write_symbols != NO_DEBUG) | |
1145 | { | |
1146 | int copies = unroll_number; | |
1147 | ||
1148 | if (loop_preconditioned) | |
1149 | copies += unroll_number - 1; | |
1150 | ||
1151 | unroll_block_trees (uid_loop_num[INSN_UID (loop_start)], copies); | |
1152 | } | |
1153 | } | |
1154 | \f | |
1155 | /* Return true if the loop can be safely, and profitably, preconditioned | |
1156 | so that the unrolled copies of the loop body don't need exit tests. | |
1157 | ||
1158 | This only works if final_value, initial_value and increment can be | |
1159 | determined, and if increment is a constant power of 2. | |
1160 | If increment is not a power of 2, then the preconditioning modulo | |
1161 | operation would require a real modulo instead of a boolean AND, and this | |
1162 | is not considered `profitable'. */ | |
1163 | ||
1164 | /* ??? If the loop is known to be executed very many times, or the machine | |
1165 | has a very cheap divide instruction, then preconditioning is a win even | |
1166 | when the increment is not a power of 2. Use RTX_COST to compute | |
1167 | whether divide is cheap. */ | |
1168 | ||
1169 | static int | |
1170 | precondition_loop_p (initial_value, final_value, increment, loop_start, | |
1171 | loop_end) | |
1172 | rtx *initial_value, *final_value, *increment; | |
1173 | rtx loop_start, loop_end; | |
1174 | { | |
1175 | int unsigned_compare, compare_dir; | |
1176 | ||
1177 | if (loop_n_iterations > 0) | |
1178 | { | |
1179 | *initial_value = const0_rtx; | |
1180 | *increment = const1_rtx; | |
1181 | *final_value = gen_rtx (CONST_INT, VOIDmode, loop_n_iterations); | |
1182 | ||
1183 | if (loop_dump_stream) | |
1184 | fprintf (loop_dump_stream, | |
1185 | "Preconditioning: Success, number of iterations known, %d.\n", | |
1186 | loop_n_iterations); | |
1187 | return 1; | |
1188 | } | |
1189 | ||
1190 | if (loop_initial_value == 0) | |
1191 | { | |
1192 | if (loop_dump_stream) | |
1193 | fprintf (loop_dump_stream, | |
1194 | "Preconditioning: Could not find initial value.\n"); | |
1195 | return 0; | |
1196 | } | |
1197 | else if (loop_increment == 0) | |
1198 | { | |
1199 | if (loop_dump_stream) | |
1200 | fprintf (loop_dump_stream, | |
1201 | "Preconditioning: Could not find increment value.\n"); | |
1202 | return 0; | |
1203 | } | |
1204 | else if (GET_CODE (loop_increment) != CONST_INT) | |
1205 | { | |
1206 | if (loop_dump_stream) | |
1207 | fprintf (loop_dump_stream, | |
1208 | "Preconditioning: Increment not a constant.\n"); | |
1209 | return 0; | |
1210 | } | |
1211 | else if ((exact_log2 (INTVAL (loop_increment)) < 0) | |
1212 | && (exact_log2 (- INTVAL (loop_increment)) < 0)) | |
1213 | { | |
1214 | if (loop_dump_stream) | |
1215 | fprintf (loop_dump_stream, | |
1216 | "Preconditioning: Increment not a constant power of 2.\n"); | |
1217 | return 0; | |
1218 | } | |
1219 | ||
1220 | /* Unsigned_compare and compare_dir can be ignored here, since they do | |
1221 | not matter for preconditioning. */ | |
1222 | ||
1223 | if (loop_final_value == 0) | |
1224 | { | |
1225 | if (loop_dump_stream) | |
1226 | fprintf (loop_dump_stream, | |
1227 | "Preconditioning: EQ comparison loop.\n"); | |
1228 | return 0; | |
1229 | } | |
1230 | ||
1231 | /* Must ensure that final_value is invariant, so call invariant_p to | |
1232 | check. Before doing so, must check regno against max_reg_before_loop | |
1233 | to make sure that the register is in the range convered by invariant_p. | |
1234 | If it isn't, then it is most likely a biv/giv which by definition are | |
1235 | not invariant. */ | |
1236 | if ((GET_CODE (loop_final_value) == REG | |
1237 | && REGNO (loop_final_value) >= max_reg_before_loop) | |
1238 | || (GET_CODE (loop_final_value) == PLUS | |
1239 | && REGNO (XEXP (loop_final_value, 0)) >= max_reg_before_loop) | |
1240 | || ! invariant_p (loop_final_value)) | |
1241 | { | |
1242 | if (loop_dump_stream) | |
1243 | fprintf (loop_dump_stream, | |
1244 | "Preconditioning: Final value not invariant.\n"); | |
1245 | return 0; | |
1246 | } | |
1247 | ||
1248 | /* Fail for floating point values, since the caller of this function | |
1249 | does not have code to deal with them. */ | |
1250 | if (GET_MODE_CLASS (GET_MODE (loop_final_value)) == MODE_FLOAT | |
1251 | || GET_MODE_CLASS (GET_MODE (loop_initial_value) == MODE_FLOAT)) | |
1252 | { | |
1253 | if (loop_dump_stream) | |
1254 | fprintf (loop_dump_stream, | |
1255 | "Preconditioning: Floating point final or initial value.\n"); | |
1256 | return 0; | |
1257 | } | |
1258 | ||
1259 | /* Now set initial_value to be the iteration_var, since that may be a | |
1260 | simpler expression, and is guaranteed to be correct if all of the | |
1261 | above tests succeed. | |
1262 | ||
1263 | We can not use the initial_value as calculated, because it will be | |
1264 | one too small for loops of the form "while (i-- > 0)". We can not | |
1265 | emit code before the loop_skip_over insns to fix this problem as this | |
1266 | will then give a number one too large for loops of the form | |
1267 | "while (--i > 0)". | |
1268 | ||
1269 | Note that all loops that reach here are entered at the top, because | |
1270 | this function is not called if the loop starts with a jump. */ | |
1271 | ||
1272 | /* Fail if loop_iteration_var is not live before loop_start, since we need | |
1273 | to test its value in the preconditioning code. */ | |
1274 | ||
1275 | if (uid_luid[regno_first_uid[REGNO (loop_iteration_var)]] | |
1276 | > INSN_LUID (loop_start)) | |
1277 | { | |
1278 | if (loop_dump_stream) | |
1279 | fprintf (loop_dump_stream, | |
1280 | "Preconditioning: Iteration var not live before loop start.\n"); | |
1281 | return 0; | |
1282 | } | |
1283 | ||
1284 | *initial_value = loop_iteration_var; | |
1285 | *increment = loop_increment; | |
1286 | *final_value = loop_final_value; | |
1287 | ||
1288 | /* Success! */ | |
1289 | if (loop_dump_stream) | |
1290 | fprintf (loop_dump_stream, "Preconditioning: Successful.\n"); | |
1291 | return 1; | |
1292 | } | |
1293 | ||
1294 | ||
1295 | /* All pseudo-registers must be mapped to themselves. Two hard registers | |
1296 | must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_ | |
1297 | REGNUM, to avoid function-inlining specific conversions of these | |
1298 | registers. All other hard regs can not be mapped because they may be | |
1299 | used with different | |
1300 | modes. */ | |
1301 | ||
1302 | static void | |
1303 | init_reg_map (map, maxregnum) | |
1304 | struct inline_remap *map; | |
1305 | int maxregnum; | |
1306 | { | |
1307 | int i; | |
1308 | ||
1309 | for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--) | |
1310 | map->reg_map[i] = regno_reg_rtx[i]; | |
1311 | /* Just clear the rest of the entries. */ | |
1312 | for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--) | |
1313 | map->reg_map[i] = 0; | |
1314 | ||
1315 | map->reg_map[VIRTUAL_STACK_VARS_REGNUM] | |
1316 | = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM]; | |
1317 | map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM] | |
1318 | = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM]; | |
1319 | } | |
1320 | \f | |
1321 | /* Strength-reduction will often emit code for optimized biv/givs which | |
1322 | calculates their value in a temporary register, and then copies the result | |
1323 | to the iv. This procedure reconstructs the pattern computing the iv; | |
1324 | verifying that all operands are of the proper form. | |
1325 | ||
1326 | The return value is the amount that the giv is incremented by. */ | |
1327 | ||
1328 | static rtx | |
1329 | calculate_giv_inc (pattern, src_insn, regno) | |
1330 | rtx pattern, src_insn; | |
1331 | int regno; | |
1332 | { | |
1333 | rtx increment; | |
1334 | ||
1335 | /* Verify that we have an increment insn here. First check for a plus | |
1336 | as the set source. */ | |
1337 | if (GET_CODE (SET_SRC (pattern)) != PLUS) | |
1338 | { | |
1339 | /* SR sometimes computes the new giv value in a temp, then copies it | |
1340 | to the new_reg. */ | |
1341 | src_insn = PREV_INSN (src_insn); | |
1342 | pattern = PATTERN (src_insn); | |
1343 | if (GET_CODE (SET_SRC (pattern)) != PLUS) | |
1344 | abort (); | |
1345 | ||
1346 | /* The last insn emitted is not needed, so delete it to avoid confusing | |
1347 | the second cse pass. This insn sets the giv unnecessarily. */ | |
1348 | delete_insn (get_last_insn ()); | |
1349 | } | |
1350 | ||
1351 | /* Verify that we have a constant as the second operand of the plus. */ | |
1352 | increment = XEXP (SET_SRC (pattern), 1); | |
1353 | if (GET_CODE (increment) != CONST_INT) | |
1354 | { | |
1355 | /* SR sometimes puts the constant in a register, especially if it is | |
1356 | too big to be an add immed operand. */ | |
1357 | increment = SET_SRC (PATTERN (PREV_INSN (src_insn))); | |
1358 | ||
1359 | /* SR may have used LO_SUM to compute the constant if it is too large | |
1360 | for a load immed operand. In this case, the constant is in operand | |
1361 | one of the LO_SUM rtx. */ | |
1362 | if (GET_CODE (increment) == LO_SUM) | |
1363 | increment = XEXP (increment, 1); | |
1364 | ||
1365 | if (GET_CODE (increment) != CONST_INT) | |
1366 | abort (); | |
1367 | ||
1368 | /* The insn loading the constant into a register is not longer needed, | |
1369 | so delete it. */ | |
1370 | delete_insn (get_last_insn ()); | |
1371 | } | |
1372 | ||
1373 | /* Check that the source register is the same as the dest register. */ | |
1374 | if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG | |
1375 | || REGNO (XEXP (SET_SRC (pattern), 0)) != regno) | |
1376 | abort (); | |
1377 | ||
1378 | return increment; | |
1379 | } | |
1380 | ||
1381 | ||
1382 | /* Copy each instruction in the loop, substituting from map as appropriate. | |
1383 | This is very similar to a loop in expand_inline_function. */ | |
1384 | ||
1385 | static void | |
1386 | copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration, | |
1387 | unroll_type, start_label, loop_end, insert_before, | |
1388 | copy_notes_from) | |
1389 | rtx copy_start, copy_end; | |
1390 | struct inline_remap *map; | |
1391 | int last_iteration; | |
1392 | enum unroll_types unroll_type; | |
1393 | rtx start_label, loop_end, insert_before, copy_notes_from; | |
1394 | { | |
1395 | rtx insn, pattern; | |
1396 | rtx tem, copy; | |
1397 | int dest_reg_was_split, i; | |
1398 | rtx cc0_insn = 0; | |
1399 | rtx final_label = 0; | |
1400 | rtx giv_inc, giv_dest_reg, giv_src_reg; | |
1401 | ||
1402 | /* If this isn't the last iteration, then map any references to the | |
1403 | start_label to final_label. Final label will then be emitted immediately | |
1404 | after the end of this loop body if it was ever used. | |
1405 | ||
1406 | If this is the last iteration, then map references to the start_label | |
1407 | to itself. */ | |
1408 | if (! last_iteration) | |
1409 | { | |
1410 | final_label = gen_label_rtx (); | |
1411 | map->label_map[CODE_LABEL_NUMBER (start_label)] = final_label; | |
1412 | } | |
1413 | else | |
1414 | map->label_map[CODE_LABEL_NUMBER (start_label)] = start_label; | |
1415 | ||
1416 | start_sequence (); | |
1417 | ||
1418 | insn = copy_start; | |
1419 | do | |
1420 | { | |
1421 | insn = NEXT_INSN (insn); | |
1422 | ||
1423 | map->orig_asm_operands_vector = 0; | |
1424 | ||
1425 | switch (GET_CODE (insn)) | |
1426 | { | |
1427 | case INSN: | |
1428 | pattern = PATTERN (insn); | |
1429 | copy = 0; | |
1430 | giv_inc = 0; | |
1431 | ||
1432 | /* Check to see if this is a giv that has been combined with | |
1433 | some split address givs. (Combined in the sense that | |
1434 | `combine_givs' in loop.c has put two givs in the same register.) | |
1435 | In this case, we must search all givs based on the same biv to | |
1436 | find the address givs. Then split the address givs. | |
1437 | Do this before splitting the giv, since that may map the | |
1438 | SET_DEST to a new register. */ | |
1439 | ||
1440 | if (GET_CODE (pattern) == SET | |
1441 | && GET_CODE (SET_DEST (pattern)) == REG | |
1442 | && addr_combined_regs[REGNO (SET_DEST (pattern))]) | |
1443 | { | |
1444 | struct iv_class *bl; | |
1445 | struct induction *v, *tv; | |
1446 | int regno = REGNO (SET_DEST (pattern)); | |
1447 | ||
1448 | v = addr_combined_regs[REGNO (SET_DEST (pattern))]; | |
1449 | bl = reg_biv_class[REGNO (v->src_reg)]; | |
1450 | ||
1451 | /* Although the giv_inc amount is not needed here, we must call | |
1452 | calculate_giv_inc here since it might try to delete the | |
1453 | last insn emitted. If we wait until later to call it, | |
1454 | we might accidentally delete insns generated immediately | |
1455 | below by emit_unrolled_add. */ | |
1456 | ||
1457 | giv_inc = calculate_giv_inc (pattern, insn, regno); | |
1458 | ||
1459 | /* Now find all address giv's that were combined with this | |
1460 | giv 'v'. */ | |
1461 | for (tv = bl->giv; tv; tv = tv->next_iv) | |
1462 | if (tv->giv_type == DEST_ADDR && tv->same == v) | |
1463 | { | |
3f07e47a JW |
1464 | /* Increment the giv by the amount that was calculated in |
1465 | find_splittable_givs, and saved in add_val. */ | |
67f2de41 | 1466 | tv->dest_reg = plus_constant (tv->dest_reg, |
3f07e47a | 1467 | INTVAL (tv->add_val)); |
67f2de41 RK |
1468 | *tv->location = tv->dest_reg; |
1469 | ||
1470 | if (last_iteration && unroll_type != UNROLL_COMPLETELY) | |
1471 | { | |
1472 | /* Must emit an insn to increment the split address | |
1473 | giv. Add in the const_adjust field in case there | |
1474 | was a constant eliminated from the address. */ | |
1475 | rtx value, dest_reg; | |
1476 | ||
1477 | /* tv->dest_reg will be either a bare register, | |
1478 | or else a register plus a constant. */ | |
1479 | if (GET_CODE (tv->dest_reg) == REG) | |
1480 | dest_reg = tv->dest_reg; | |
1481 | else | |
1482 | dest_reg = XEXP (tv->dest_reg, 0); | |
1483 | ||
1484 | /* tv->dest_reg may actually be a (PLUS (REG) (CONST)) | |
1485 | here, so we must call plus_constant to add | |
1486 | the const_adjust amount before calling | |
1487 | emit_unrolled_add below. */ | |
1488 | value = plus_constant (tv->dest_reg, tv->const_adjust); | |
1489 | ||
1490 | /* The constant could be too large for an add | |
1491 | immediate, so can't directly emit an insn here. */ | |
1492 | emit_unrolled_add (dest_reg, XEXP (value, 0), | |
1493 | XEXP (value, 1)); | |
1494 | ||
1495 | /* Reset the giv to be just the register again, in case | |
1496 | it is used after the set we have just emitted. */ | |
1497 | tv->dest_reg = dest_reg; | |
1498 | *tv->location = tv->dest_reg; | |
1499 | } | |
1500 | } | |
1501 | } | |
1502 | ||
1503 | /* If this is a setting of a splittable variable, then determine | |
1504 | how to split the variable, create a new set based on this split, | |
1505 | and set up the reg_map so that later uses of the variable will | |
1506 | use the new split variable. */ | |
1507 | ||
1508 | dest_reg_was_split = 0; | |
1509 | ||
1510 | if (GET_CODE (pattern) == SET | |
1511 | && GET_CODE (SET_DEST (pattern)) == REG | |
1512 | && splittable_regs[REGNO (SET_DEST (pattern))]) | |
1513 | { | |
1514 | int regno = REGNO (SET_DEST (pattern)); | |
1515 | ||
1516 | dest_reg_was_split = 1; | |
1517 | ||
1518 | /* Compute the increment value for the giv, if it wasn't | |
1519 | already computed above. */ | |
1520 | ||
1521 | if (giv_inc == 0) | |
1522 | giv_inc = calculate_giv_inc (pattern, insn, regno); | |
1523 | giv_dest_reg = SET_DEST (pattern); | |
1524 | giv_src_reg = SET_DEST (pattern); | |
1525 | ||
1526 | if (unroll_type == UNROLL_COMPLETELY) | |
1527 | { | |
1528 | /* Completely unrolling the loop. Set the induction | |
1529 | variable to a known constant value. */ | |
1530 | ||
1531 | /* The value in splittable_regs may be an invariant | |
1532 | value, so we must use plus_constant here. */ | |
1533 | splittable_regs[regno] | |
1534 | = plus_constant (splittable_regs[regno], INTVAL (giv_inc)); | |
1535 | ||
1536 | if (GET_CODE (splittable_regs[regno]) == PLUS) | |
1537 | { | |
1538 | giv_src_reg = XEXP (splittable_regs[regno], 0); | |
1539 | giv_inc = XEXP (splittable_regs[regno], 1); | |
1540 | } | |
1541 | else | |
1542 | { | |
1543 | /* The splittable_regs value must be a REG or a | |
1544 | CONST_INT, so put the entire value in the giv_src_reg | |
1545 | variable. */ | |
1546 | giv_src_reg = splittable_regs[regno]; | |
1547 | giv_inc = const0_rtx; | |
1548 | } | |
1549 | } | |
1550 | else | |
1551 | { | |
1552 | /* Partially unrolling loop. Create a new pseudo | |
1553 | register for the iteration variable, and set it to | |
1554 | be a constant plus the original register. Except | |
1555 | on the last iteration, when the result has to | |
1556 | go back into the original iteration var register. */ | |
1557 | ||
1558 | /* Handle bivs which must be mapped to a new register | |
1559 | when split. This happens for bivs which need their | |
1560 | final value set before loop entry. The new register | |
1561 | for the biv was stored in the biv's first struct | |
1562 | induction entry by find_splittable_regs. */ | |
1563 | ||
1564 | if (regno < max_reg_before_loop | |
1565 | && reg_iv_type[regno] == BASIC_INDUCT) | |
1566 | { | |
1567 | giv_src_reg = reg_biv_class[regno]->biv->src_reg; | |
1568 | giv_dest_reg = giv_src_reg; | |
1569 | } | |
1570 | ||
1571 | #if 0 | |
1572 | /* If non-reduced/final-value givs were split, then | |
1573 | this would have to remap those givs also. See | |
1574 | find_splittable_regs. */ | |
1575 | #endif | |
1576 | ||
1577 | splittable_regs[regno] | |
1578 | = gen_rtx (CONST_INT, VOIDmode, | |
1579 | INTVAL (giv_inc) | |
1580 | + INTVAL (splittable_regs[regno])); | |
1581 | giv_inc = splittable_regs[regno]; | |
1582 | ||
1583 | /* Now split the induction variable by changing the dest | |
1584 | of this insn to a new register, and setting its | |
1585 | reg_map entry to point to this new register. | |
1586 | ||
1587 | If this is the last iteration, and this is the last insn | |
1588 | that will update the iv, then reuse the original dest, | |
1589 | to ensure that the iv will have the proper value when | |
1590 | the loop exits or repeats. | |
1591 | ||
1592 | Using splittable_regs_updates here like this is safe, | |
1593 | because it can only be greater than one if all | |
1594 | instructions modifying the iv are always executed in | |
1595 | order. */ | |
1596 | ||
1597 | if (! last_iteration | |
1598 | || (splittable_regs_updates[regno]-- != 1)) | |
1599 | { | |
1600 | tem = gen_reg_rtx (GET_MODE (giv_src_reg)); | |
1601 | giv_dest_reg = tem; | |
1602 | map->reg_map[regno] = tem; | |
1603 | } | |
1604 | else | |
1605 | map->reg_map[regno] = giv_src_reg; | |
1606 | } | |
1607 | ||
1608 | /* The constant being added could be too large for an add | |
1609 | immediate, so can't directly emit an insn here. */ | |
1610 | emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc); | |
1611 | copy = get_last_insn (); | |
1612 | pattern = PATTERN (copy); | |
1613 | } | |
1614 | else | |
1615 | { | |
1616 | pattern = copy_rtx_and_substitute (pattern, map); | |
1617 | copy = emit_insn (pattern); | |
1618 | } | |
1619 | /* REG_NOTES will be copied later. */ | |
1620 | ||
1621 | #ifdef HAVE_cc0 | |
1622 | /* If this insn is setting CC0, it may need to look at | |
1623 | the insn that uses CC0 to see what type of insn it is. | |
1624 | In that case, the call to recog via validate_change will | |
1625 | fail. So don't substitute constants here. Instead, | |
1626 | do it when we emit the following insn. | |
1627 | ||
1628 | For example, see the pyr.md file. That machine has signed and | |
1629 | unsigned compares. The compare patterns must check the | |
1630 | following branch insn to see which what kind of compare to | |
1631 | emit. | |
1632 | ||
1633 | If the previous insn set CC0, substitute constants on it as | |
1634 | well. */ | |
1635 | if (sets_cc0_p (copy) != 0) | |
1636 | cc0_insn = copy; | |
1637 | else | |
1638 | { | |
1639 | if (cc0_insn) | |
1640 | try_constants (cc0_insn, map); | |
1641 | cc0_insn = 0; | |
1642 | try_constants (copy, map); | |
1643 | } | |
1644 | #else | |
1645 | try_constants (copy, map); | |
1646 | #endif | |
1647 | ||
1648 | /* Make split induction variable constants `permanent' since we | |
1649 | know there are no backward branches across iteration variable | |
1650 | settings which would invalidate this. */ | |
1651 | if (dest_reg_was_split) | |
1652 | { | |
1653 | int regno = REGNO (SET_DEST (pattern)); | |
1654 | ||
1655 | if (map->const_age_map[regno] == map->const_age) | |
1656 | map->const_age_map[regno] = -1; | |
1657 | } | |
1658 | break; | |
1659 | ||
1660 | case JUMP_INSN: | |
1661 | if (JUMP_LABEL (insn) == start_label && insn == copy_end | |
1662 | && ! last_iteration) | |
1663 | { | |
1664 | /* This is a branch to the beginning of the loop; this is the | |
1665 | last insn being copied; and this is not the last iteration. | |
1666 | In this case, we want to change the original fall through | |
1667 | case to be a branch past the end of the loop, and the | |
1668 | original jump label case to fall_through. */ | |
1669 | ||
1670 | int fall_through; | |
1671 | ||
1672 | /* Never map the label in this case. */ | |
1673 | pattern = copy_rtx (PATTERN (insn)); | |
1674 | ||
1675 | /* Assume a conditional branch, since the code above | |
1676 | does not let unconditional branches be copied. */ | |
1677 | if (! condjump_p (insn)) | |
1678 | abort (); | |
1679 | fall_through | |
1680 | = (XEXP (SET_SRC (PATTERN (insn)), 2) == pc_rtx) + 1; | |
1681 | ||
1682 | /* Set the fall through case to the exit label. Must | |
1683 | create a new label_ref since they can't be shared. */ | |
1684 | XEXP (SET_SRC (pattern), fall_through) | |
1685 | = gen_rtx (LABEL_REF, VOIDmode, exit_label); | |
1686 | ||
1687 | /* Set the original branch case to fall through. */ | |
1688 | XEXP (SET_SRC (pattern), 3 - fall_through) | |
1689 | = pc_rtx; | |
1690 | } | |
1691 | else | |
1692 | pattern = copy_rtx_and_substitute (PATTERN (insn), map); | |
1693 | ||
1694 | copy = emit_jump_insn (pattern); | |
1695 | ||
1696 | #ifdef HAVE_cc0 | |
1697 | if (cc0_insn) | |
1698 | try_constants (cc0_insn, map); | |
1699 | cc0_insn = 0; | |
1700 | #endif | |
1701 | try_constants (copy, map); | |
1702 | ||
1703 | /* Set the jump label of COPY correctly to avoid problems with | |
1704 | later passes of unroll_loop, if INSN had jump label set. */ | |
1705 | if (JUMP_LABEL (insn)) | |
1706 | { | |
1707 | /* Can't use the label_map for every insn, since this may be | |
1708 | the backward branch, and hence the label was not mapped. */ | |
1709 | if (GET_CODE (pattern) == SET) | |
1710 | { | |
1711 | tem = SET_SRC (pattern); | |
1712 | if (GET_CODE (tem) == LABEL_REF) | |
1713 | JUMP_LABEL (copy) = XEXP (tem, 0); | |
1714 | else if (GET_CODE (tem) == IF_THEN_ELSE) | |
1715 | { | |
1716 | if (XEXP (tem, 1) != pc_rtx) | |
1717 | JUMP_LABEL (copy) = XEXP (XEXP (tem, 1), 0); | |
1718 | else | |
1719 | JUMP_LABEL (copy) = XEXP (XEXP (tem, 2), 0); | |
1720 | } | |
1721 | else | |
1722 | abort (); | |
1723 | } | |
1724 | else | |
1725 | { | |
1726 | /* An unrecognizable jump insn, probably the entry jump | |
1727 | for a switch statement. This label must have been mapped, | |
1728 | so just use the label_map to get the new jump label. */ | |
1729 | JUMP_LABEL (copy) = map->label_map[CODE_LABEL_NUMBER | |
1730 | (JUMP_LABEL (insn))]; | |
1731 | } | |
1732 | ||
1733 | /* If this is a non-local jump, then must increase the label | |
1734 | use count so that the label will not be deleted when the | |
1735 | original jump is deleted. */ | |
1736 | LABEL_NUSES (JUMP_LABEL (copy))++; | |
1737 | } | |
1738 | else if (GET_CODE (PATTERN (copy)) == ADDR_VEC | |
1739 | || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC) | |
1740 | { | |
1741 | rtx pat = PATTERN (copy); | |
1742 | int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC; | |
1743 | int len = XVECLEN (pat, diff_vec_p); | |
1744 | int i; | |
1745 | ||
1746 | for (i = 0; i < len; i++) | |
1747 | LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++; | |
1748 | } | |
1749 | ||
1750 | /* If this used to be a conditional jump insn but whose branch | |
1751 | direction is now known, we must do something special. */ | |
1752 | if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value) | |
1753 | { | |
1754 | #ifdef HAVE_cc0 | |
1755 | /* The previous insn set cc0 for us. So delete it. */ | |
1756 | delete_insn (PREV_INSN (copy)); | |
1757 | #endif | |
1758 | ||
1759 | /* If this is now a no-op, delete it. */ | |
1760 | if (map->last_pc_value == pc_rtx) | |
1761 | { | |
1762 | delete_insn (copy); | |
1763 | copy = 0; | |
1764 | } | |
1765 | else | |
1766 | /* Otherwise, this is unconditional jump so we must put a | |
1767 | BARRIER after it. We could do some dead code elimination | |
1768 | here, but jump.c will do it just as well. */ | |
1769 | emit_barrier (); | |
1770 | } | |
1771 | break; | |
1772 | ||
1773 | case CALL_INSN: | |
1774 | pattern = copy_rtx_and_substitute (PATTERN (insn), map); | |
1775 | copy = emit_call_insn (pattern); | |
1776 | ||
1777 | #ifdef HAVE_cc0 | |
1778 | if (cc0_insn) | |
1779 | try_constants (cc0_insn, map); | |
1780 | cc0_insn = 0; | |
1781 | #endif | |
1782 | try_constants (copy, map); | |
1783 | ||
1784 | /* Be lazy and assume CALL_INSNs clobber all hard registers. */ | |
1785 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
1786 | map->const_equiv_map[i] = 0; | |
1787 | break; | |
1788 | ||
1789 | case CODE_LABEL: | |
1790 | /* If this is the loop start label, then we don't need to emit a | |
1791 | copy of this label since no one will use it. */ | |
1792 | ||
1793 | if (insn != start_label) | |
1794 | { | |
1795 | copy = emit_label (map->label_map[CODE_LABEL_NUMBER (insn)]); | |
1796 | map->const_age++; | |
1797 | } | |
1798 | break; | |
1799 | ||
1800 | case BARRIER: | |
1801 | copy = emit_barrier (); | |
1802 | break; | |
1803 | ||
1804 | case NOTE: | |
1805 | if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED) | |
1806 | copy = emit_note (NOTE_SOURCE_FILE (insn), | |
1807 | NOTE_LINE_NUMBER (insn)); | |
1808 | else | |
1809 | copy = 0; | |
1810 | break; | |
1811 | ||
1812 | default: | |
1813 | abort (); | |
1814 | break; | |
1815 | } | |
1816 | ||
1817 | map->insn_map[INSN_UID (insn)] = copy; | |
1818 | } | |
1819 | while (insn != copy_end); | |
1820 | ||
1821 | /* Now copy the REG_NOTES. */ | |
1822 | insn = copy_start; | |
1823 | do | |
1824 | { | |
1825 | insn = NEXT_INSN (insn); | |
1826 | if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN | |
1827 | || GET_CODE (insn) == CALL_INSN) | |
1828 | && map->insn_map[INSN_UID (insn)]) | |
1829 | REG_NOTES (map->insn_map[INSN_UID (insn)]) | |
1830 | = copy_rtx_and_substitute (REG_NOTES (insn), map); | |
1831 | } | |
1832 | while (insn != copy_end); | |
1833 | ||
1834 | /* There may be notes between copy_notes_from and loop_end. Emit a copy of | |
1835 | each of these notes here, since there may be some important ones, such as | |
1836 | NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last | |
1837 | iteration, because the original notes won't be deleted. | |
1838 | ||
1839 | We can't use insert_before here, because when from preconditioning, | |
1840 | insert_before points before the loop. We can't use copy_end, because | |
1841 | there may be insns already inserted after it (which we don't want to | |
1842 | copy) when not from preconditioning code. */ | |
1843 | ||
1844 | if (! last_iteration) | |
1845 | { | |
1846 | for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn)) | |
1847 | { | |
1848 | if (GET_CODE (insn) == NOTE | |
1849 | && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED) | |
1850 | emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn)); | |
1851 | } | |
1852 | } | |
1853 | ||
1854 | if (final_label && LABEL_NUSES (final_label) > 0) | |
1855 | emit_label (final_label); | |
1856 | ||
1857 | tem = gen_sequence (); | |
1858 | end_sequence (); | |
1859 | emit_insn_before (tem, insert_before); | |
1860 | } | |
1861 | \f | |
1862 | /* Emit an insn, using the expand_binop to ensure that a valid insn is | |
1863 | emitted. This will correctly handle the case where the increment value | |
1864 | won't fit in the immediate field of a PLUS insns. */ | |
1865 | ||
1866 | void | |
1867 | emit_unrolled_add (dest_reg, src_reg, increment) | |
1868 | rtx dest_reg, src_reg, increment; | |
1869 | { | |
1870 | rtx result; | |
1871 | ||
1872 | result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment, | |
1873 | dest_reg, 0, OPTAB_LIB_WIDEN); | |
1874 | ||
1875 | if (dest_reg != result) | |
1876 | emit_move_insn (dest_reg, result); | |
1877 | } | |
1878 | \f | |
1879 | /* Searches the insns between INSN and LOOP_END. Returns 1 if there | |
1880 | is a backward branch in that range that branches to somewhere between | |
1881 | LOOP_START and INSN. Returns 0 otherwise. */ | |
1882 | ||
1883 | /* ??? This is quadratic algorithm. Could be rewriten to be linear. | |
1884 | In practice, this is not a problem, because this function is seldom called, | |
1885 | and uses a negligible amount of CPU time on average. */ | |
1886 | ||
1887 | static int | |
1888 | back_branch_in_range_p (insn, loop_start, loop_end) | |
1889 | rtx insn; | |
1890 | rtx loop_start, loop_end; | |
1891 | { | |
1892 | rtx p, q, target_insn; | |
1893 | ||
1894 | /* Stop before we get to the backward branch at the end of the loop. */ | |
1895 | loop_end = prev_nonnote_insn (loop_end); | |
1896 | if (GET_CODE (loop_end) == BARRIER) | |
1897 | loop_end = PREV_INSN (loop_end); | |
1898 | ||
1899 | /* Check in case insn has been deleted, search forward for first non | |
1900 | deleted insn following it. */ | |
1901 | while (INSN_DELETED_P (insn)) | |
1902 | insn = NEXT_INSN (insn); | |
1903 | ||
1904 | /* Check for the case where insn is the last insn in the loop. */ | |
1905 | if (insn == loop_end) | |
1906 | return 0; | |
1907 | ||
1908 | for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p)) | |
1909 | { | |
1910 | if (GET_CODE (p) == JUMP_INSN) | |
1911 | { | |
1912 | target_insn = JUMP_LABEL (p); | |
1913 | ||
1914 | /* Search from loop_start to insn, to see if one of them is | |
1915 | the target_insn. We can't use INSN_LUID comparisons here, | |
1916 | since insn may not have an LUID entry. */ | |
1917 | for (q = loop_start; q != insn; q = NEXT_INSN (q)) | |
1918 | if (q == target_insn) | |
1919 | return 1; | |
1920 | } | |
1921 | } | |
1922 | ||
1923 | return 0; | |
1924 | } | |
1925 | ||
1926 | /* Try to generate the simplest rtx for the expression | |
1927 | (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial | |
1928 | value of giv's. */ | |
1929 | ||
1930 | static rtx | |
1931 | fold_rtx_mult_add (mult1, mult2, add1, mode) | |
1932 | rtx mult1, mult2, add1; | |
1933 | enum machine_mode mode; | |
1934 | { | |
1935 | rtx temp, mult_res; | |
1936 | rtx result; | |
1937 | ||
1938 | /* The modes must all be the same. This should always be true. For now, | |
1939 | check to make sure. */ | |
1940 | if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode) | |
1941 | || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode) | |
1942 | || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode)) | |
1943 | abort (); | |
1944 | ||
1945 | /* Ensure that if at least one of mult1/mult2 are constant, then mult2 | |
1946 | will be a constant. */ | |
1947 | if (GET_CODE (mult1) == CONST_INT) | |
1948 | { | |
1949 | temp = mult2; | |
1950 | mult2 = mult1; | |
1951 | mult1 = temp; | |
1952 | } | |
1953 | ||
1954 | mult_res = simplify_binary_operation (MULT, mode, mult1, mult2); | |
1955 | if (! mult_res) | |
1956 | mult_res = gen_rtx (MULT, mode, mult1, mult2); | |
1957 | ||
1958 | /* Again, put the constant second. */ | |
1959 | if (GET_CODE (add1) == CONST_INT) | |
1960 | { | |
1961 | temp = add1; | |
1962 | add1 = mult_res; | |
1963 | mult_res = temp; | |
1964 | } | |
1965 | ||
1966 | result = simplify_binary_operation (PLUS, mode, add1, mult_res); | |
1967 | if (! result) | |
1968 | result = gen_rtx (PLUS, mode, add1, mult_res); | |
1969 | ||
1970 | return result; | |
1971 | } | |
1972 | ||
1973 | /* Searches the list of induction struct's for the biv BL, to try to calculate | |
1974 | the total increment value for one iteration of the loop as a constant. | |
1975 | ||
1976 | Returns the increment value as an rtx, simplified as much as possible, | |
1977 | if it can be calculated. Otherwise, returns 0. */ | |
1978 | ||
1979 | rtx | |
1980 | biv_total_increment (bl, loop_start, loop_end) | |
1981 | struct iv_class *bl; | |
1982 | rtx loop_start, loop_end; | |
1983 | { | |
1984 | struct induction *v; | |
1985 | rtx result; | |
1986 | ||
1987 | /* For increment, must check every instruction that sets it. Each | |
1988 | instruction must be executed only once each time through the loop. | |
1989 | To verify this, we check that the the insn is always executed, and that | |
1990 | there are no backward branches after the insn that branch to before it. | |
1991 | Also, the insn must have a mult_val of one (to make sure it really is | |
1992 | an increment). */ | |
1993 | ||
1994 | result = const0_rtx; | |
1995 | for (v = bl->biv; v; v = v->next_iv) | |
1996 | { | |
1997 | if (v->always_computable && v->mult_val == const1_rtx | |
1998 | && ! back_branch_in_range_p (v->insn, loop_start, loop_end)) | |
1999 | result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode); | |
2000 | else | |
2001 | return 0; | |
2002 | } | |
2003 | ||
2004 | return result; | |
2005 | } | |
2006 | ||
2007 | /* Determine the initial value of the iteration variable, and the amount | |
2008 | that it is incremented each loop. Use the tables constructed by | |
2009 | the strength reduction pass to calculate these values. | |
2010 | ||
2011 | Initial_value and/or increment are set to zero if their values could not | |
2012 | be calculated. */ | |
2013 | ||
2014 | static void | |
2015 | iteration_info (iteration_var, initial_value, increment, loop_start, loop_end) | |
2016 | rtx iteration_var, *initial_value, *increment; | |
2017 | rtx loop_start, loop_end; | |
2018 | { | |
2019 | struct iv_class *bl; | |
2020 | struct induction *v, *b; | |
2021 | ||
2022 | /* Clear the result values, in case no answer can be found. */ | |
2023 | *initial_value = 0; | |
2024 | *increment = 0; | |
2025 | ||
2026 | /* The iteration variable can be either a giv or a biv. Check to see | |
2027 | which it is, and compute the variable's initial value, and increment | |
2028 | value if possible. */ | |
2029 | ||
2030 | /* If this is a new register, can't handle it since we don't have any | |
2031 | reg_iv_type entry for it. */ | |
2032 | if (REGNO (iteration_var) >= max_reg_before_loop) | |
2033 | { | |
2034 | if (loop_dump_stream) | |
2035 | fprintf (loop_dump_stream, | |
2036 | "Loop unrolling: No reg_iv_type entry for iteration var.\n"); | |
2037 | return; | |
2038 | } | |
2039 | /* Reject iteration variables larger than the host long size, since they | |
2040 | could result in a number of iterations greater than the range of our | |
2041 | `unsigned long' variable loop_n_iterations. */ | |
2042 | else if (GET_MODE_BITSIZE (GET_MODE (iteration_var)) > HOST_BITS_PER_LONG) | |
2043 | { | |
2044 | if (loop_dump_stream) | |
2045 | fprintf (loop_dump_stream, | |
2046 | "Loop unrolling: Iteration var rejected because mode larger than host long.\n"); | |
2047 | return; | |
2048 | } | |
2049 | else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT) | |
2050 | { | |
2051 | if (loop_dump_stream) | |
2052 | fprintf (loop_dump_stream, | |
2053 | "Loop unrolling: Iteration var not an interger.\n"); | |
2054 | return; | |
2055 | } | |
2056 | else if (reg_iv_type[REGNO (iteration_var)] == BASIC_INDUCT) | |
2057 | { | |
2058 | /* Grab initial value, only useful if it is a constant. */ | |
2059 | bl = reg_biv_class[REGNO (iteration_var)]; | |
2060 | *initial_value = bl->initial_value; | |
2061 | ||
2062 | *increment = biv_total_increment (bl, loop_start, loop_end); | |
2063 | } | |
2064 | else if (reg_iv_type[REGNO (iteration_var)] == GENERAL_INDUCT) | |
2065 | { | |
2066 | #if 1 | |
2067 | /* ??? The code below does not work because the incorrect number of | |
2068 | iterations is calculated when the biv is incremented after the giv | |
2069 | is set (which is the usual case). This can probably be accounted | |
2070 | for by biasing the initial_value by subtracting the amount of the | |
2071 | increment that occurs between the giv set and the giv test. However, | |
2072 | a giv as an iterator is very rare, so it does not seem worthwhile | |
2073 | to handle this. */ | |
2074 | /* ??? An example failure is: i = 6; do {;} while (i++ < 9). */ | |
2075 | if (loop_dump_stream) | |
2076 | fprintf (loop_dump_stream, | |
2077 | "Loop unrolling: Giv iterators are not handled.\n"); | |
2078 | return; | |
2079 | #else | |
2080 | /* Initial value is mult_val times the biv's initial value plus | |
2081 | add_val. Only useful if it is a constant. */ | |
2082 | v = reg_iv_info[REGNO (iteration_var)]; | |
2083 | bl = reg_biv_class[REGNO (v->src_reg)]; | |
2084 | *initial_value = fold_rtx_mult_add (v->mult_val, bl->initial_value, | |
2085 | v->add_val, v->mode); | |
2086 | ||
2087 | /* Increment value is mult_val times the increment value of the biv. */ | |
2088 | ||
2089 | *increment = biv_total_increment (bl, loop_start, loop_end); | |
2090 | if (*increment) | |
2091 | *increment = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, | |
2092 | v->mode); | |
2093 | #endif | |
2094 | } | |
2095 | else | |
2096 | { | |
2097 | if (loop_dump_stream) | |
2098 | fprintf (loop_dump_stream, | |
2099 | "Loop unrolling: Not basic or general induction var.\n"); | |
2100 | return; | |
2101 | } | |
2102 | } | |
2103 | ||
2104 | /* Calculate the approximate final value of the iteration variable | |
2105 | which has an loop exit test with code COMPARISON_CODE and comparison value | |
2106 | of COMPARISON_VALUE. Also returns an indication of whether the comparison | |
2107 | was signed or unsigned, and the direction of the comparison. This info is | |
2108 | needed to calculate the number of loop iterations. */ | |
2109 | ||
2110 | static rtx | |
2111 | approx_final_value (comparison_code, comparison_value, unsigned_p, compare_dir) | |
2112 | enum rtx_code comparison_code; | |
2113 | rtx comparison_value; | |
2114 | int *unsigned_p; | |
2115 | int *compare_dir; | |
2116 | { | |
2117 | /* Calculate the final value of the induction variable. | |
2118 | The exact final value depends on the branch operator, and increment sign. | |
2119 | This is only an approximate value. It will be wrong if the iteration | |
2120 | variable is not incremented by one each time through the loop, and | |
2121 | approx final value - start value % increment != 0. */ | |
2122 | ||
2123 | *unsigned_p = 0; | |
2124 | switch (comparison_code) | |
2125 | { | |
2126 | case LEU: | |
2127 | *unsigned_p = 1; | |
2128 | case LE: | |
2129 | *compare_dir = 1; | |
2130 | return plus_constant (comparison_value, 1); | |
2131 | case GEU: | |
2132 | *unsigned_p = 1; | |
2133 | case GE: | |
2134 | *compare_dir = -1; | |
2135 | return plus_constant (comparison_value, -1); | |
2136 | case EQ: | |
2137 | /* Can not calculate a final value for this case. */ | |
2138 | *compare_dir = 0; | |
2139 | return 0; | |
2140 | case LTU: | |
2141 | *unsigned_p = 1; | |
2142 | case LT: | |
2143 | *compare_dir = 1; | |
2144 | return comparison_value; | |
2145 | break; | |
2146 | case GTU: | |
2147 | *unsigned_p = 1; | |
2148 | case GT: | |
2149 | *compare_dir = -1; | |
2150 | return comparison_value; | |
2151 | case NE: | |
2152 | *compare_dir = 0; | |
2153 | return comparison_value; | |
2154 | default: | |
2155 | abort (); | |
2156 | } | |
2157 | } | |
2158 | ||
2159 | /* For each biv and giv, determine whether it can be safely split into | |
2160 | a different variable for each unrolled copy of the loop body. If it | |
2161 | is safe to split, then indicate that by saving some useful info | |
2162 | in the splittable_regs array. | |
2163 | ||
2164 | If the loop is being completely unrolled, then splittable_regs will hold | |
2165 | the current value of the induction variable while the loop is unrolled. | |
2166 | It must be set to the initial value of the induction variable here. | |
2167 | Otherwise, splittable_regs will hold the difference between the current | |
2168 | value of the induction variable and the value the induction variable had | |
2169 | at the top of the loop. It must be set to the value 0 here. */ | |
2170 | ||
2171 | /* ?? If the loop is only unrolled twice, then most of the restrictions to | |
2172 | constant values are unnecessary, since we can easily calculate increment | |
2173 | values in this case even if nothing is constant. The increment value | |
2174 | should not involve a multiply however. */ | |
2175 | ||
2176 | /* ?? Even if the biv/giv increment values aren't constant, it may still | |
2177 | be beneficial to split the variable if the loop is only unrolled a few | |
2178 | times, since multiplies by small integers (1,2,3,4) are very cheap. */ | |
2179 | ||
2180 | static int | |
2181 | find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before, | |
2182 | unroll_number) | |
2183 | enum unroll_types unroll_type; | |
2184 | rtx loop_start, loop_end; | |
2185 | rtx end_insert_before; | |
2186 | int unroll_number; | |
2187 | { | |
2188 | struct iv_class *bl; | |
2189 | rtx increment, tem; | |
2190 | rtx biv_final_value; | |
2191 | int biv_splittable; | |
2192 | int result = 0; | |
2193 | ||
2194 | for (bl = loop_iv_list; bl; bl = bl->next) | |
2195 | { | |
2196 | /* Biv_total_increment must return a constant value, | |
2197 | otherwise we can not calculate the split values. */ | |
2198 | ||
2199 | increment = biv_total_increment (bl, loop_start, loop_end); | |
2200 | if (! increment || GET_CODE (increment) != CONST_INT) | |
2201 | continue; | |
2202 | ||
2203 | /* The loop must be unrolled completely, or else have a known number | |
2204 | of iterations and only one exit, or else the biv must be dead | |
2205 | outside the loop, or else the final value must be known. Otherwise, | |
2206 | it is unsafe to split the biv since it may not have the proper | |
2207 | value on loop exit. */ | |
2208 | ||
2209 | /* loop_number_exit_labels is non-zero if the loop has an exit other than | |
2210 | a fall through at the end. */ | |
2211 | ||
2212 | biv_splittable = 1; | |
2213 | biv_final_value = 0; | |
2214 | if (unroll_type != UNROLL_COMPLETELY | |
2215 | && (loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]] | |
2216 | || unroll_type == UNROLL_NAIVE) | |
2217 | && (uid_luid[regno_last_uid[bl->regno]] >= INSN_LUID (loop_end) | |
2218 | || ! bl->init_insn | |
2219 | || INSN_UID (bl->init_insn) >= max_uid_for_loop | |
2220 | || (uid_luid[regno_first_uid[bl->regno]] | |
2221 | < INSN_LUID (bl->init_insn)) | |
2222 | || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set))) | |
2223 | && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end))) | |
2224 | biv_splittable = 0; | |
2225 | ||
2226 | /* If final value is non-zero, then must emit an instruction which sets | |
2227 | the value of the biv to the proper value. This is done after | |
2228 | handling all of the givs, since some of them may need to use the | |
2229 | biv's value in their initialization code. */ | |
2230 | ||
2231 | /* This biv is splittable. If completely unrolling the loop, save | |
2232 | the biv's initial value. Otherwise, save the constant zero. */ | |
2233 | ||
2234 | if (biv_splittable == 1) | |
2235 | { | |
2236 | if (unroll_type == UNROLL_COMPLETELY) | |
2237 | { | |
2238 | /* If the initial value of the biv is itself (i.e. it is too | |
2239 | complicated for strength_reduce to compute), or is a hard | |
2240 | register, then we must create a new psuedo reg to hold the | |
2241 | initial value of the biv. */ | |
2242 | ||
2243 | if (GET_CODE (bl->initial_value) == REG | |
2244 | && (REGNO (bl->initial_value) == bl->regno | |
2245 | || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER)) | |
2246 | { | |
2247 | rtx tem = gen_reg_rtx (bl->biv->mode); | |
2248 | ||
2249 | emit_insn_before (gen_move_insn (tem, bl->biv->src_reg), | |
2250 | loop_start); | |
2251 | ||
2252 | if (loop_dump_stream) | |
2253 | fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n", | |
2254 | bl->regno, REGNO (tem)); | |
2255 | ||
2256 | splittable_regs[bl->regno] = tem; | |
2257 | } | |
2258 | else | |
2259 | splittable_regs[bl->regno] = bl->initial_value; | |
2260 | } | |
2261 | else | |
2262 | splittable_regs[bl->regno] = const0_rtx; | |
2263 | ||
2264 | /* Save the number of instructions that modify the biv, so that | |
2265 | we can treat the last one specially. */ | |
2266 | ||
2267 | splittable_regs_updates[bl->regno] = bl->biv_count; | |
2268 | ||
2269 | result++; | |
2270 | ||
2271 | if (loop_dump_stream) | |
2272 | fprintf (loop_dump_stream, | |
2273 | "Biv %d safe to split.\n", bl->regno); | |
2274 | } | |
2275 | ||
2276 | /* Check every giv that depends on this biv to see whether it is | |
2277 | splittable also. Even if the biv isn't splittable, givs which | |
2278 | depend on it may be splittable if the biv is live outside the | |
2279 | loop, and the givs aren't. */ | |
2280 | ||
2281 | result = find_splittable_givs (bl, unroll_type, loop_start, loop_end, | |
2282 | increment, unroll_number, result); | |
2283 | ||
2284 | /* If final value is non-zero, then must emit an instruction which sets | |
2285 | the value of the biv to the proper value. This is done after | |
2286 | handling all of the givs, since some of them may need to use the | |
2287 | biv's value in their initialization code. */ | |
2288 | if (biv_final_value) | |
2289 | { | |
2290 | /* If the loop has multiple exits, emit the insns before the | |
2291 | loop to ensure that it will always be executed no matter | |
2292 | how the loop exits. Otherwise emit the insn after the loop, | |
2293 | since this is slightly more efficient. */ | |
2294 | if (! loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
2295 | emit_insn_before (gen_move_insn (bl->biv->src_reg, | |
2296 | biv_final_value), | |
2297 | end_insert_before); | |
2298 | else | |
2299 | { | |
2300 | /* Create a new register to hold the value of the biv, and then | |
2301 | set the biv to its final value before the loop start. The biv | |
2302 | is set to its final value before loop start to ensure that | |
2303 | this insn will always be executed, no matter how the loop | |
2304 | exits. */ | |
2305 | rtx tem = gen_reg_rtx (bl->biv->mode); | |
2306 | emit_insn_before (gen_move_insn (tem, bl->biv->src_reg), | |
2307 | loop_start); | |
2308 | emit_insn_before (gen_move_insn (bl->biv->src_reg, | |
2309 | biv_final_value), | |
2310 | loop_start); | |
2311 | ||
2312 | if (loop_dump_stream) | |
2313 | fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n", | |
2314 | REGNO (bl->biv->src_reg), REGNO (tem)); | |
2315 | ||
2316 | /* Set up the mapping from the original biv register to the new | |
2317 | register. */ | |
2318 | bl->biv->src_reg = tem; | |
2319 | } | |
2320 | } | |
2321 | } | |
2322 | return result; | |
2323 | } | |
2324 | ||
2325 | /* For every giv based on the biv BL, check to determine whether it is | |
2326 | splittable. This is a subroutine to find_splittable_regs (). */ | |
2327 | ||
2328 | static int | |
2329 | find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment, | |
2330 | unroll_number, result) | |
2331 | struct iv_class *bl; | |
2332 | enum unroll_types unroll_type; | |
2333 | rtx loop_start, loop_end; | |
2334 | rtx increment; | |
2335 | int unroll_number, result; | |
2336 | { | |
2337 | struct induction *v; | |
2338 | rtx final_value; | |
2339 | rtx tem; | |
2340 | ||
2341 | for (v = bl->giv; v; v = v->next_iv) | |
2342 | { | |
2343 | rtx giv_inc, value; | |
2344 | ||
2345 | /* Only split the giv if it has already been reduced, or if the loop is | |
2346 | being completely unrolled. */ | |
2347 | if (unroll_type != UNROLL_COMPLETELY && v->ignore) | |
2348 | continue; | |
2349 | ||
2350 | /* The giv can be split if the insn that sets the giv is executed once | |
2351 | and only once on every iteration of the loop. */ | |
2352 | /* An address giv can always be split. v->insn is just a use not a set, | |
2353 | and hence it does not matter whether it is always executed. All that | |
2354 | matters is that all the biv increments are always executed, and we | |
2355 | won't reach here if they aren't. */ | |
2356 | if (v->giv_type != DEST_ADDR | |
2357 | && (! v->always_computable | |
2358 | || back_branch_in_range_p (v->insn, loop_start, loop_end))) | |
2359 | continue; | |
2360 | ||
2361 | /* The giv increment value must be a constant. */ | |
2362 | giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx, | |
2363 | v->mode); | |
2364 | if (! giv_inc || GET_CODE (giv_inc) != CONST_INT) | |
2365 | continue; | |
2366 | ||
2367 | /* The loop must be unrolled completely, or else have a known number of | |
2368 | iterations and only one exit, or else the giv must be dead outside | |
2369 | the loop, or else the final value of the giv must be known. | |
2370 | Otherwise, it is not safe to split the giv since it may not have the | |
2371 | proper value on loop exit. */ | |
2372 | ||
2373 | /* The used outside loop test will fail for DEST_ADDR givs. They are | |
2374 | never used outside the loop anyways, so it is always safe to split a | |
2375 | DEST_ADDR giv. */ | |
2376 | ||
2377 | final_value = 0; | |
2378 | if (unroll_type != UNROLL_COMPLETELY | |
2379 | && (loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]] | |
2380 | || unroll_type == UNROLL_NAIVE) | |
2381 | && v->giv_type != DEST_ADDR | |
2382 | && ((regno_first_uid[REGNO (v->dest_reg)] != INSN_UID (v->insn) | |
2383 | /* Check for the case where the pseudo is set by a shift/add | |
2384 | sequence, in which case the first insn setting the pseudo | |
2385 | is the first insn of the shift/add sequence. */ | |
2386 | && (! (tem = find_reg_note (v->insn, REG_RETVAL, 0)) | |
2387 | || (regno_first_uid[REGNO (v->dest_reg)] | |
2388 | != INSN_UID (XEXP (tem, 0))))) | |
2389 | /* Line above always fails if INSN was moved by loop opt. */ | |
2390 | || (uid_luid[regno_last_uid[REGNO (v->dest_reg)]] | |
2391 | >= INSN_LUID (loop_end))) | |
2392 | && ! (final_value = v->final_value)) | |
2393 | continue; | |
2394 | ||
2395 | #if 0 | |
2396 | /* Currently, non-reduced/final-value givs are never split. */ | |
2397 | /* Should emit insns after the loop if possible, as the biv final value | |
2398 | code below does. */ | |
2399 | ||
2400 | /* If the final value is non-zero, and the giv has not been reduced, | |
2401 | then must emit an instruction to set the final value. */ | |
2402 | if (final_value && !v->new_reg) | |
2403 | { | |
2404 | /* Create a new register to hold the value of the giv, and then set | |
2405 | the giv to its final value before the loop start. The giv is set | |
2406 | to its final value before loop start to ensure that this insn | |
2407 | will always be executed, no matter how we exit. */ | |
2408 | tem = gen_reg_rtx (v->mode); | |
2409 | emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start); | |
2410 | emit_insn_before (gen_move_insn (v->dest_reg, final_value), | |
2411 | loop_start); | |
2412 | ||
2413 | if (loop_dump_stream) | |
2414 | fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n", | |
2415 | REGNO (v->dest_reg), REGNO (tem)); | |
2416 | ||
2417 | v->src_reg = tem; | |
2418 | } | |
2419 | #endif | |
2420 | ||
2421 | /* This giv is splittable. If completely unrolling the loop, save the | |
2422 | giv's initial value. Otherwise, save the constant zero for it. */ | |
2423 | ||
2424 | if (unroll_type == UNROLL_COMPLETELY) | |
2425 | /* It is not safe to use bl->initial_value here, because it may not | |
2426 | be invariant. It is safe to use the initial value stored in | |
2427 | the splittable_regs array. */ | |
2428 | value = fold_rtx_mult_add (v->mult_val, splittable_regs[bl->regno], | |
2429 | v->add_val, v->mode); | |
2430 | else | |
2431 | value = const0_rtx; | |
2432 | ||
2433 | if (v->new_reg) | |
2434 | { | |
2435 | /* If the giv is an address destination, it could be something other | |
2436 | than a simple register, these have to be treated differently. */ | |
2437 | if (v->giv_type == DEST_REG) | |
2438 | splittable_regs[REGNO (v->new_reg)] = value; | |
2439 | ||
2440 | /* If an addr giv was combined with another addr giv, then we | |
2441 | can only split this giv if the addr giv it was combined with | |
2442 | was reduced. This is because the value of v->new_reg is | |
2443 | meaningless in this case. (There is no problem if it was | |
2444 | combined with a dest_reg giv which wasn't reduced, v->new_reg | |
2445 | is still meaningful in this case.) */ | |
2446 | ||
2447 | else if (v->same && v->same->giv_type == DEST_ADDR | |
2448 | && ! v->same->new_reg) | |
2449 | { | |
2450 | if (loop_dump_stream) | |
2451 | fprintf (loop_dump_stream, | |
2452 | "DEST_ADDR giv not split, because combined with unreduced DEST_ADDR giv.\n"); | |
2453 | } | |
2454 | else | |
2455 | { | |
2456 | /* Splitting address givs is useful since it will often allow us | |
2457 | to eliminate some increment insns for the base giv as | |
2458 | unnecessary. */ | |
2459 | ||
2460 | /* If the addr giv is combined with a dest_reg giv, then all | |
2461 | references to that dest reg will be remapped, which is NOT | |
2462 | what we want for split addr regs. We always create a new | |
2463 | register for the split addr giv, just to be safe. */ | |
2464 | ||
2465 | /* ??? If there are multiple address givs which have been | |
2466 | combined with the same dest_reg giv, then we may only need | |
2467 | one new register for them. Pulling out constants below will | |
2468 | catch some of the common cases of this. Currently, I leave | |
2469 | the work of simplifying multiple address givs to the | |
2470 | following cse pass. */ | |
2471 | ||
2472 | v->const_adjust = 0; | |
2473 | if (unroll_type != UNROLL_COMPLETELY) | |
2474 | { | |
2475 | /* If not completely unrolling the loop, then create a new | |
2476 | register to hold the split value of the DEST_ADDR giv. | |
2477 | Emit insn to initialize its value before loop start. */ | |
2478 | tem = gen_reg_rtx (v->mode); | |
2479 | ||
2480 | /* If the address giv has a constant in its new_reg value, | |
2481 | then this constant can be pulled out and put in value, | |
2482 | instead of being part of the initialization code. */ | |
2483 | ||
2484 | if (GET_CODE (v->new_reg) == PLUS | |
2485 | && GET_CODE (XEXP (v->new_reg, 1)) == CONST_INT) | |
2486 | { | |
2487 | v->dest_reg | |
2488 | = plus_constant (tem, INTVAL (XEXP (v->new_reg,1))); | |
2489 | ||
2490 | /* Only succeed if this will give valid addresses. | |
2491 | Try to validate both the first and the last | |
2492 | address resulting from loop unrolling, if | |
2493 | one fails, then can't do const elim here. */ | |
2494 | if (memory_address_p (v->mode, v->dest_reg) | |
2495 | && memory_address_p (v->mode, | |
2496 | plus_constant (v->dest_reg, | |
2497 | INTVAL (giv_inc) | |
2498 | * (unroll_number - 1)))) | |
2499 | { | |
2500 | /* Save the negative of the eliminated const, so | |
2501 | that we can calculate the dest_reg's increment | |
2502 | value later. */ | |
2503 | v->const_adjust = - INTVAL (XEXP (v->new_reg, 1)); | |
2504 | ||
2505 | v->new_reg = XEXP (v->new_reg, 0); | |
2506 | if (loop_dump_stream) | |
2507 | fprintf (loop_dump_stream, | |
2508 | "Eliminating constant from giv %d\n", | |
2509 | REGNO (tem)); | |
2510 | } | |
2511 | else | |
2512 | v->dest_reg = tem; | |
2513 | } | |
2514 | else | |
2515 | v->dest_reg = tem; | |
2516 | ||
2517 | /* If the address hasn't been checked for validity yet, do so | |
2518 | now, and fail completely if either the first or the last | |
2519 | unrolled copy of the address is not a valid address. */ | |
2520 | if (v->dest_reg == tem | |
2521 | && (! memory_address_p (v->mode, v->dest_reg) | |
2522 | || ! memory_address_p (v->mode, | |
2523 | plus_constant (v->dest_reg, | |
2524 | INTVAL (giv_inc) | |
2525 | * (unroll_number -1))))) | |
2526 | { | |
2527 | if (loop_dump_stream) | |
2528 | fprintf (loop_dump_stream, | |
2529 | "Illegal address for giv at insn %d\n", | |
2530 | INSN_UID (v->insn)); | |
2531 | continue; | |
2532 | } | |
2533 | ||
2534 | /* To initialize the new register, just move the value of | |
2535 | new_reg into it. This is not guaranteed to give a valid | |
2536 | instruction on machines with complex addressing modes. | |
2537 | If we can't recognize it, then delete it and emit insns | |
2538 | to calculate the value from scratch. */ | |
2539 | emit_insn_before (gen_rtx (SET, VOIDmode, tem, | |
2540 | copy_rtx (v->new_reg)), | |
2541 | loop_start); | |
2542 | if (! recog_memoized (PREV_INSN (loop_start))) | |
2543 | { | |
2544 | delete_insn (PREV_INSN (loop_start)); | |
2545 | emit_iv_add_mult (bl->initial_value, v->mult_val, | |
2546 | v->add_val, tem, loop_start); | |
2547 | if (loop_dump_stream) | |
2548 | fprintf (loop_dump_stream, | |
2549 | "Illegal init insn, rewritten.\n"); | |
2550 | } | |
2551 | } | |
2552 | else | |
2553 | { | |
2554 | v->dest_reg = value; | |
2555 | ||
2556 | /* Check the resulting address for validity, and fail | |
2557 | if the resulting address would be illegal. */ | |
2558 | if (! memory_address_p (v->mode, v->dest_reg) | |
2559 | || ! memory_address_p (v->mode, | |
2560 | plus_constant (v->dest_reg, | |
2561 | INTVAL (giv_inc) * | |
2562 | (unroll_number -1)))) | |
2563 | { | |
2564 | if (loop_dump_stream) | |
2565 | fprintf (loop_dump_stream, | |
2566 | "Illegal address for giv at insn %d\n", | |
2567 | INSN_UID (v->insn)); | |
2568 | continue; | |
2569 | } | |
2570 | } | |
2571 | ||
2572 | /* Store the value of dest_reg into the insn. This sharing | |
2573 | will not be a problem as this insn will always be copied | |
2574 | later. */ | |
2575 | ||
2576 | *v->location = v->dest_reg; | |
2577 | ||
2578 | /* If this address giv is combined with a dest reg giv, then | |
2579 | save the base giv's induction pointer so that we will be | |
2580 | able to handle this address giv properly. The base giv | |
2581 | itself does not have to be splittable. */ | |
2582 | ||
2583 | if (v->same && v->same->giv_type == DEST_REG) | |
2584 | addr_combined_regs[REGNO (v->same->new_reg)] = v->same; | |
2585 | ||
2586 | if (GET_CODE (v->new_reg) == REG) | |
2587 | { | |
2588 | /* This giv maybe hasn't been combined with any others. | |
2589 | Make sure that it's giv is marked as splittable here. */ | |
2590 | ||
2591 | splittable_regs[REGNO (v->new_reg)] = value; | |
2592 | ||
2593 | /* Make it appear to depend upon itself, so that the | |
2594 | giv will be properly split in the main loop above. */ | |
2595 | if (! v->same) | |
2596 | { | |
2597 | v->same = v; | |
2598 | addr_combined_regs[REGNO (v->new_reg)] = v; | |
2599 | } | |
2600 | } | |
3f07e47a JW |
2601 | |
2602 | /* Overwrite the old add_val, which is no longer needed, and | |
2603 | substitute the amount that the giv is incremented on each | |
2604 | iteration. We need to save this somewhere, so we know how | |
2605 | much to increment split DEST_ADDR giv's in copy_loop_body. */ | |
2606 | ||
2607 | v->add_val = giv_inc; | |
2608 | ||
67f2de41 RK |
2609 | if (loop_dump_stream) |
2610 | fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n"); | |
2611 | } | |
2612 | } | |
2613 | else | |
2614 | { | |
2615 | #if 0 | |
2616 | /* Currently, unreduced giv's can't be split. This is not too much | |
2617 | of a problem since unreduced giv's are not live across loop | |
2618 | iterations anyways. When unrolling a loop completely though, | |
2619 | it makes sense to reduce&split givs when possible, as this will | |
2620 | result in simpler instructions, and will not require that a reg | |
2621 | be live across loop iterations. */ | |
2622 | ||
2623 | splittable_regs[REGNO (v->dest_reg)] = value; | |
2624 | fprintf (stderr, "Giv %d at insn %d not reduced\n", | |
2625 | REGNO (v->dest_reg), INSN_UID (v->insn)); | |
2626 | #else | |
2627 | continue; | |
2628 | #endif | |
2629 | } | |
2630 | ||
2631 | /* Givs are only updated once by definition. Mark it so if this is | |
2632 | a splittable register. Don't need to do anything for address givs | |
2633 | where this may not be a register. */ | |
2634 | ||
2635 | if (GET_CODE (v->new_reg) == REG) | |
2636 | splittable_regs_updates[REGNO (v->new_reg)] = 1; | |
2637 | ||
2638 | result++; | |
2639 | ||
2640 | if (loop_dump_stream) | |
2641 | { | |
2642 | int regnum; | |
2643 | ||
2644 | if (GET_CODE (v->dest_reg) == CONST_INT) | |
2645 | regnum = -1; | |
2646 | else if (GET_CODE (v->dest_reg) != REG) | |
2647 | regnum = REGNO (XEXP (v->dest_reg, 0)); | |
2648 | else | |
2649 | regnum = REGNO (v->dest_reg); | |
2650 | fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n", | |
2651 | regnum, INSN_UID (v->insn)); | |
2652 | } | |
2653 | } | |
2654 | ||
2655 | return result; | |
2656 | } | |
2657 | \f | |
2658 | /* Try to prove that the register is dead after the loop exits. Trace every | |
2659 | loop exit looking for an insn that will always be executed, which sets | |
2660 | the register to some value, and appears before the first use of the register | |
2661 | is found. If successful, then return 1, otherwise return 0. */ | |
2662 | ||
2663 | /* ?? Could be made more intelligent in the handling of jumps, so that | |
2664 | it can search past if statements and other similar structures. */ | |
2665 | ||
2666 | static int | |
2667 | reg_dead_after_loop (reg, loop_start, loop_end) | |
2668 | rtx reg, loop_start, loop_end; | |
2669 | { | |
2670 | rtx insn, label; | |
2671 | enum rtx_code code; | |
2672 | ||
2673 | /* HACK: Must also search the loop fall through exit, create a label_ref | |
2674 | here which points to the loop_end, and append the loop_number_exit_labels | |
2675 | list to it. */ | |
2676 | label = gen_rtx (LABEL_REF, VOIDmode, loop_end); | |
2677 | LABEL_NEXTREF (label) | |
2678 | = loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]; | |
2679 | ||
2680 | for ( ; label; label = LABEL_NEXTREF (label)) | |
2681 | { | |
2682 | /* Succeed if find an insn which sets the biv or if reach end of | |
2683 | function. Fail if find an insn that uses the biv, or if come to | |
2684 | a conditional jump. */ | |
2685 | ||
2686 | insn = NEXT_INSN (XEXP (label, 0)); | |
2687 | while (1) | |
2688 | { | |
2689 | if (insn == 0) | |
2690 | break; | |
2691 | ||
2692 | if ((code = GET_CODE (insn)) == INSN || code == JUMP_INSN | |
2693 | || code == CALL_INSN) | |
2694 | { | |
2695 | if (GET_CODE (PATTERN (insn)) == SET) | |
2696 | { | |
2697 | if (reg_mentioned_p (reg, SET_SRC (PATTERN (insn)))) | |
2698 | return 0; | |
2699 | if (SET_DEST (PATTERN (insn)) == reg) | |
2700 | break; | |
2701 | if (reg_mentioned_p (reg, SET_DEST (PATTERN (insn)))) | |
2702 | return 0; | |
2703 | } | |
2704 | else if (reg_mentioned_p (reg, PATTERN (insn))) | |
2705 | return 0; | |
2706 | } | |
2707 | if (code == JUMP_INSN) | |
2708 | { | |
2709 | if (GET_CODE (PATTERN (insn)) == RETURN) | |
2710 | break; | |
2711 | else if (! simplejump_p (insn)) | |
2712 | return 0; | |
2713 | else | |
2714 | { | |
2715 | insn = JUMP_LABEL (insn); | |
2716 | /* If this branches to a code label after a LOOP_BEG or | |
2717 | a LOOP_CONT note, then assume it is a loop back edge. | |
2718 | Must fail in that case to prevent going into an infinite | |
2719 | loop trying to trace infinite loops. | |
2720 | ||
2721 | In the presence of syntax errors, this may be a jump to | |
2722 | a CODE_LABEL that was never emitted. Fail in this case | |
2723 | also. */ | |
2724 | ||
2725 | if (! PREV_INSN (insn) | |
2726 | || (GET_CODE (PREV_INSN (insn)) == NOTE | |
2727 | && ((NOTE_LINE_NUMBER (PREV_INSN (insn)) | |
2728 | == NOTE_INSN_LOOP_BEG) | |
2729 | || (NOTE_LINE_NUMBER (PREV_INSN (insn)) | |
2730 | == NOTE_INSN_LOOP_CONT)))) | |
2731 | return 0; | |
2732 | } | |
2733 | } | |
2734 | ||
2735 | insn = NEXT_INSN (insn); | |
2736 | } | |
2737 | } | |
2738 | ||
2739 | /* Success, the register is dead on all loop exits. */ | |
2740 | return 1; | |
2741 | } | |
2742 | ||
2743 | /* Try to calculate the final value of the biv, the value it will have at | |
2744 | the end of the loop. If we can do it, return that value. */ | |
2745 | ||
2746 | rtx | |
2747 | final_biv_value (bl, loop_start, loop_end) | |
2748 | struct iv_class *bl; | |
2749 | rtx loop_start, loop_end; | |
2750 | { | |
2751 | rtx increment, tem; | |
2752 | ||
2753 | /* The final value for reversed bivs must be calculated differently than | |
2754 | for ordinary bivs. In this case, there is already an insn after the | |
2755 | loop which sets this biv's final value (if necessary), and there are | |
2756 | no other loop exits, so we can return any value. */ | |
2757 | if (bl->reversed) | |
2758 | { | |
2759 | if (loop_dump_stream) | |
2760 | fprintf (loop_dump_stream, | |
2761 | "Final biv value for %d, reversed biv.\n", bl->regno); | |
2762 | ||
2763 | return const0_rtx; | |
2764 | } | |
2765 | ||
2766 | /* Try to calculate the final value as initial value + (number of iterations | |
2767 | * increment). For this to work, increment must be invariant, the only | |
2768 | exit from the loop must be the fall through at the bottom (otherwise | |
2769 | it may not have its final value when the loop exits), and the initial | |
2770 | value of the biv must be invariant. */ | |
2771 | ||
2772 | if (loop_n_iterations != 0 | |
2773 | && ! loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]] | |
2774 | && invariant_p (bl->initial_value)) | |
2775 | { | |
2776 | increment = biv_total_increment (bl, loop_start, loop_end); | |
2777 | ||
2778 | if (increment && invariant_p (increment)) | |
2779 | { | |
2780 | /* Can calculate the loop exit value, emit insns after loop | |
2781 | end to calculate this value into a temporary register in | |
2782 | case it is needed later. */ | |
2783 | ||
2784 | tem = gen_reg_rtx (bl->biv->mode); | |
2785 | emit_iv_add_mult (increment, | |
2786 | gen_rtx (CONST_INT, VOIDmode, loop_n_iterations), | |
2787 | bl->initial_value, tem, NEXT_INSN (loop_end)); | |
2788 | ||
2789 | if (loop_dump_stream) | |
2790 | fprintf (loop_dump_stream, | |
2791 | "Final biv value for %d, calculated.\n", bl->regno); | |
2792 | ||
2793 | return tem; | |
2794 | } | |
2795 | } | |
2796 | ||
2797 | /* Check to see if the biv is dead at all loop exits. */ | |
2798 | if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end)) | |
2799 | { | |
2800 | if (loop_dump_stream) | |
2801 | fprintf (loop_dump_stream, | |
2802 | "Final biv value for %d, biv dead after loop exit.\n", | |
2803 | bl->regno); | |
2804 | ||
2805 | return const0_rtx; | |
2806 | } | |
2807 | ||
2808 | return 0; | |
2809 | } | |
2810 | ||
2811 | /* Try to calculate the final value of the giv, the value it will have at | |
2812 | the end of the loop. If we can do it, return that value. */ | |
2813 | ||
2814 | rtx | |
2815 | final_giv_value (v, loop_start, loop_end) | |
2816 | struct induction *v; | |
2817 | rtx loop_start, loop_end; | |
2818 | { | |
2819 | struct iv_class *bl; | |
2820 | rtx reg, insn, pattern; | |
2821 | rtx increment, tem; | |
2822 | enum rtx_code code; | |
2823 | rtx insert_before; | |
2824 | ||
2825 | bl = reg_biv_class[REGNO (v->src_reg)]; | |
2826 | ||
2827 | /* The final value for givs which depend on reversed bivs must be calculated | |
2828 | differently than for ordinary givs. In this case, there is already an | |
2829 | insn after the loop which sets this giv's final value (if necessary), | |
2830 | and there are no other loop exits, so we can return any value. */ | |
2831 | if (bl->reversed) | |
2832 | { | |
2833 | if (loop_dump_stream) | |
2834 | fprintf (loop_dump_stream, | |
2835 | "Final giv value for %d, depends on reversed biv\n", | |
2836 | REGNO (v->dest_reg)); | |
2837 | return const0_rtx; | |
2838 | } | |
2839 | ||
2840 | /* Try to calculate the final value as a function of the biv it depends | |
2841 | upon. The only exit from the loop must be the fall through at the bottom | |
2842 | (otherwise it may not have its final value when the loop exits). */ | |
2843 | ||
2844 | /* ??? Can calculate the final giv value by subtracting off the | |
2845 | extra biv increments times the giv's mult_val. The loop must have | |
2846 | only one exit for this to work, but the loop iterations does not need | |
2847 | to be known. */ | |
2848 | ||
2849 | if (loop_n_iterations != 0 | |
2850 | && ! loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]]) | |
2851 | { | |
2852 | /* ?? It is tempting to use the biv's value here since these insns will | |
2853 | be put after the loop, and hence the biv will have its final value | |
2854 | then. However, this fails if the biv is subsequently eliminated. | |
2855 | Perhaps determine whether biv's are eliminable before trying to | |
2856 | determine whether giv's are replaceable so that we can use the | |
2857 | biv value here if it is not eliminable. */ | |
2858 | ||
2859 | increment = biv_total_increment (bl, loop_start, loop_end); | |
2860 | ||
2861 | if (increment && invariant_p (increment)) | |
2862 | { | |
2863 | /* Can calculate the loop exit value of its biv as | |
2864 | (loop_n_iterations * increment) + initial_value */ | |
2865 | ||
2866 | /* The loop exit value of the giv is then | |
2867 | (final_biv_value - extra increments) * mult_val + add_val. | |
2868 | The extra increments are any increments to the biv which | |
2869 | occur in the loop after the giv's value is calculated. | |
2870 | We must search from the insn that sets the giv to the end | |
2871 | of the loop to calculate this value. */ | |
2872 | ||
2873 | insert_before = NEXT_INSN (loop_end); | |
2874 | ||
2875 | /* Put the final biv value in tem. */ | |
2876 | tem = gen_reg_rtx (bl->biv->mode); | |
2877 | emit_iv_add_mult (increment, | |
2878 | gen_rtx (CONST_INT, VOIDmode, loop_n_iterations), | |
2879 | bl->initial_value, tem, insert_before); | |
2880 | ||
2881 | /* Subtract off extra increments as we find them. */ | |
2882 | for (insn = NEXT_INSN (v->insn); insn != loop_end; | |
2883 | insn = NEXT_INSN (insn)) | |
2884 | { | |
2885 | if (GET_CODE (insn) == INSN | |
2886 | && GET_CODE (PATTERN (insn)) == SET | |
2887 | && SET_DEST (PATTERN (insn)) == v->src_reg) | |
2888 | { | |
2889 | pattern = PATTERN (insn); | |
2890 | if (GET_CODE (SET_SRC (pattern)) != PLUS) | |
2891 | { | |
2892 | /* Sometimes a biv is computed in a temp reg, | |
2893 | and then copied into the biv reg. */ | |
2894 | pattern = PATTERN (PREV_INSN (insn)); | |
2895 | if (GET_CODE (SET_SRC (pattern)) != PLUS) | |
2896 | abort (); | |
2897 | } | |
2898 | if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG | |
2899 | || REGNO (XEXP (SET_SRC (pattern), 0)) != bl->regno) | |
2900 | abort (); | |
2901 | ||
2902 | tem = expand_binop (GET_MODE (tem), sub_optab, tem, | |
2903 | XEXP (SET_SRC (pattern), 1), 0, 0, | |
2904 | OPTAB_LIB_WIDEN); | |
2905 | } | |
2906 | } | |
2907 | ||
2908 | /* Now calculate the giv's final value. */ | |
2909 | emit_iv_add_mult (tem, v->mult_val, v->add_val, tem, | |
2910 | insert_before); | |
2911 | ||
2912 | if (loop_dump_stream) | |
2913 | fprintf (loop_dump_stream, | |
2914 | "Final giv value for %d, calc from biv's value.\n", | |
2915 | REGNO (v->dest_reg)); | |
2916 | ||
2917 | return tem; | |
2918 | } | |
2919 | } | |
2920 | ||
2921 | /* Replaceable giv's should never reach here. */ | |
2922 | if (v->replaceable) | |
2923 | abort (); | |
2924 | ||
2925 | /* Check to see if the biv is dead at all loop exits. */ | |
2926 | if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end)) | |
2927 | { | |
2928 | if (loop_dump_stream) | |
2929 | fprintf (loop_dump_stream, | |
2930 | "Final giv value for %d, giv dead after loop exit.\n", | |
2931 | REGNO (v->dest_reg)); | |
2932 | ||
2933 | return const0_rtx; | |
2934 | } | |
2935 | ||
2936 | return 0; | |
2937 | } | |
2938 | ||
2939 | ||
2940 | /* Calculate the number of loop iterations. Returns the exact number of loop | |
2941 | iterations if it can be calculated, otherwise retusns zero. */ | |
2942 | ||
2943 | unsigned long | |
2944 | loop_iterations (loop_start, loop_end) | |
2945 | rtx loop_start, loop_end; | |
2946 | { | |
2947 | rtx comparison, comparison_value; | |
2948 | rtx iteration_var, initial_value, increment, final_value; | |
2949 | enum rtx_code comparison_code; | |
2950 | int i, increment_dir; | |
2951 | int unsigned_compare, compare_dir, final_larger; | |
2952 | unsigned long tempu; | |
2953 | rtx last_loop_insn; | |
2954 | ||
2955 | /* First find the iteration variable. If the last insn is a conditional | |
2956 | branch, and the insn before tests a register value, make that the | |
2957 | iteration variable. */ | |
2958 | ||
2959 | loop_initial_value = 0; | |
2960 | loop_increment = 0; | |
2961 | loop_final_value = 0; | |
2962 | loop_iteration_var = 0; | |
2963 | ||
2964 | last_loop_insn = prev_nonnote_insn (loop_end); | |
2965 | ||
2966 | comparison = get_condition_for_loop (last_loop_insn); | |
2967 | if (comparison == 0) | |
2968 | { | |
2969 | if (loop_dump_stream) | |
2970 | fprintf (loop_dump_stream, | |
2971 | "Loop unrolling: No final conditional branch found.\n"); | |
2972 | return 0; | |
2973 | } | |
2974 | ||
2975 | /* ??? Get_condition may switch position of induction variable and | |
2976 | invariant register when it canonicalizes the comparison. */ | |
2977 | ||
2978 | comparison_code = GET_CODE (comparison); | |
2979 | iteration_var = XEXP (comparison, 0); | |
2980 | comparison_value = XEXP (comparison, 1); | |
2981 | ||
2982 | if (GET_CODE (iteration_var) != REG) | |
2983 | { | |
2984 | if (loop_dump_stream) | |
2985 | fprintf (loop_dump_stream, | |
2986 | "Loop unrolling: Comparison not against register.\n"); | |
2987 | return 0; | |
2988 | } | |
2989 | ||
2990 | /* Loop iterations is always called before any new registers are created | |
2991 | now, so this should never occur. */ | |
2992 | ||
2993 | if (REGNO (iteration_var) >= max_reg_before_loop) | |
2994 | abort (); | |
2995 | ||
2996 | iteration_info (iteration_var, &initial_value, &increment, | |
2997 | loop_start, loop_end); | |
2998 | if (initial_value == 0) | |
2999 | /* iteration_info already printed a message. */ | |
3000 | return 0; | |
3001 | ||
3002 | if (increment == 0) | |
3003 | { | |
3004 | if (loop_dump_stream) | |
3005 | fprintf (loop_dump_stream, | |
3006 | "Loop unrolling: Increment value can't be calculated.\n"); | |
3007 | return 0; | |
3008 | } | |
3009 | if (GET_CODE (increment) != CONST_INT) | |
3010 | { | |
3011 | if (loop_dump_stream) | |
3012 | fprintf (loop_dump_stream, | |
3013 | "Loop unrolling: Increment value not constant.\n"); | |
3014 | return 0; | |
3015 | } | |
3016 | if (GET_CODE (initial_value) != CONST_INT) | |
3017 | { | |
3018 | if (loop_dump_stream) | |
3019 | fprintf (loop_dump_stream, | |
3020 | "Loop unrolling: Initial value not constant.\n"); | |
3021 | return 0; | |
3022 | } | |
3023 | ||
3024 | /* If the comparison value is an invariant register, then try to find | |
3025 | its value from the insns before the start of the loop. */ | |
3026 | ||
3027 | if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value)) | |
3028 | { | |
3029 | rtx insn, set; | |
3030 | ||
3031 | for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn)) | |
3032 | { | |
3033 | if (GET_CODE (insn) == CODE_LABEL) | |
3034 | break; | |
3035 | ||
3036 | else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i' | |
3037 | && (set = single_set (insn)) | |
3038 | && (SET_DEST (set) == comparison_value)) | |
3039 | { | |
3040 | rtx note = find_reg_note (insn, REG_EQUAL, 0); | |
3041 | ||
3042 | if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST) | |
3043 | comparison_value = XEXP (note, 0); | |
3044 | ||
3045 | break; | |
3046 | } | |
3047 | } | |
3048 | } | |
3049 | ||
3050 | final_value = approx_final_value (comparison_code, comparison_value, | |
3051 | &unsigned_compare, &compare_dir); | |
3052 | ||
3053 | /* Save the calculated values describing this loop's bounds, in case | |
3054 | precondition_loop_p will need them later. These values can not be | |
3055 | recalculated inside precondition_loop_p because strength reduction | |
3056 | optimizations may obscure the loop's structure. */ | |
3057 | ||
3058 | loop_iteration_var = iteration_var; | |
3059 | loop_initial_value = initial_value; | |
3060 | loop_increment = increment; | |
3061 | loop_final_value = final_value; | |
3062 | ||
3063 | if (final_value == 0) | |
3064 | { | |
3065 | if (loop_dump_stream) | |
3066 | fprintf (loop_dump_stream, | |
3067 | "Loop unrolling: EQ comparison loop.\n"); | |
3068 | return 0; | |
3069 | } | |
3070 | else if (GET_CODE (final_value) != CONST_INT) | |
3071 | { | |
3072 | if (loop_dump_stream) | |
3073 | fprintf (loop_dump_stream, | |
3074 | "Loop unrolling: Final value not constant.\n"); | |
3075 | return 0; | |
3076 | } | |
3077 | ||
3078 | /* ?? Final value and initial value do not have to be constants. | |
3079 | Only their difference has to be constant. When the iteration variable | |
3080 | is an array address, the final value and initial value might both | |
3081 | be addresses with the same base but different constant offsets. | |
3082 | Final value must be invariant for this to work. | |
3083 | ||
3084 | To do this, need someway to find the values of registers which are | |
3085 | invariant. */ | |
3086 | ||
3087 | /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */ | |
3088 | if (unsigned_compare) | |
3089 | final_larger | |
3090 | = ((unsigned) INTVAL (final_value) > (unsigned) INTVAL (initial_value)) - | |
3091 | ((unsigned) INTVAL (final_value) < (unsigned) INTVAL (initial_value)); | |
3092 | else | |
3093 | final_larger = (INTVAL (final_value) > INTVAL (initial_value)) - | |
3094 | (INTVAL (final_value) < INTVAL (initial_value)); | |
3095 | ||
3096 | if (INTVAL (increment) > 0) | |
3097 | increment_dir = 1; | |
3098 | else if (INTVAL (increment) == 0) | |
3099 | increment_dir = 0; | |
3100 | else | |
3101 | increment_dir = -1; | |
3102 | ||
3103 | /* There are 27 different cases: compare_dir = -1, 0, 1; | |
3104 | final_larger = -1, 0, 1; increment_dir = -1, 0, 1. | |
3105 | There are 4 normal cases, 4 reverse cases (where the iteration variable | |
3106 | will overflow before the loop exits), 4 infinite loop cases, and 15 | |
3107 | immediate exit (0 or 1 iteration depending on loop type) cases. | |
3108 | Only try to optimize the normal cases. */ | |
3109 | ||
3110 | /* (compare_dir/final_larger/increment_dir) | |
3111 | Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1) | |
3112 | Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1) | |
3113 | Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0) | |
3114 | Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */ | |
3115 | ||
3116 | /* ?? If the meaning of reverse loops (where the iteration variable | |
3117 | will overflow before the loop exits) is undefined, then could | |
3118 | eliminate all of these special checks, and just always assume | |
3119 | the loops are normal/immediate/infinite. Note that this means | |
3120 | the sign of increment_dir does not have to be known. Also, | |
3121 | since it does not really hurt if immediate exit loops or infinite loops | |
3122 | are optimized, then that case could be ignored also, and hence all | |
3123 | loops can be optimized. | |
3124 | ||
3125 | According to ANSI Spec, the reverse loop case result is undefined, | |
3126 | because the action on overflow is undefined. | |
3127 | ||
3128 | See also the special test for NE loops below. */ | |
3129 | ||
3130 | if (final_larger == increment_dir && final_larger != 0 | |
3131 | && (final_larger == compare_dir || compare_dir == 0)) | |
3132 | /* Normal case. */ | |
3133 | ; | |
3134 | else | |
3135 | { | |
3136 | if (loop_dump_stream) | |
3137 | fprintf (loop_dump_stream, | |
3138 | "Loop unrolling: Not normal loop.\n"); | |
3139 | return 0; | |
3140 | } | |
3141 | ||
3142 | /* Calculate the number of iterations, final_value is only an approximation, | |
3143 | so correct for that. Note that tempu and loop_n_iterations are | |
3144 | unsigned, because they can be as large as 2^n - 1. */ | |
3145 | ||
3146 | i = INTVAL (increment); | |
3147 | if (i > 0) | |
3148 | tempu = INTVAL (final_value) - INTVAL (initial_value); | |
3149 | else if (i < 0) | |
3150 | { | |
3151 | tempu = INTVAL (initial_value) - INTVAL (final_value); | |
3152 | i = -i; | |
3153 | } | |
3154 | else | |
3155 | abort (); | |
3156 | ||
3157 | /* For NE tests, make sure that the iteration variable won't miss the | |
3158 | final value. If tempu mod i is not zero, then the iteration variable | |
3159 | will overflow before the loop exits, and we can not calculate the | |
3160 | number of iterations. */ | |
3161 | if (compare_dir == 0 && (tempu % i) != 0) | |
3162 | return 0; | |
3163 | ||
3164 | return tempu / i + ((tempu % i) != 0); | |
3165 | } |