1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor { int factor, count; } factors[NUM_FACTORS]
144 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
148 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
154 #include "insn-config.h"
155 #include "integrate.h"
159 #include "function.h"
164 /* This controls which loops are unrolled, and by how much we unroll
167 #ifndef MAX_UNROLLED_INSNS
168 #define MAX_UNROLLED_INSNS 100
171 /* Indexed by register number, if non-zero, then it contains a pointer
172 to a struct induction for a DEST_REG giv which has been combined with
173 one of more address givs. This is needed because whenever such a DEST_REG
174 giv is modified, we must modify the value of all split address givs
175 that were combined with this DEST_REG giv. */
177 static struct induction **addr_combined_regs;
179 /* Indexed by register number, if this is a splittable induction variable,
180 then this will hold the current value of the register, which depends on the
183 static rtx *splittable_regs;
185 /* Indexed by register number, if this is a splittable induction variable,
186 this indicates if it was made from a derived giv. */
187 static char *derived_regs;
189 /* Indexed by register number, if this is a splittable induction variable,
190 then this will hold the number of instructions in the loop that modify
191 the induction variable. Used to ensure that only the last insn modifying
192 a split iv will update the original iv of the dest. */
194 static int *splittable_regs_updates;
196 /* Forward declarations. */
198 static void init_reg_map PARAMS ((struct inline_remap *, int));
199 static rtx calculate_giv_inc PARAMS ((rtx, rtx, unsigned int));
200 static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
201 static void final_reg_note_copy PARAMS ((rtx, struct inline_remap *));
202 static void copy_loop_body PARAMS ((rtx, rtx, struct inline_remap *, rtx, int,
203 enum unroll_types, rtx, rtx, rtx, rtx));
204 static void iteration_info PARAMS ((const struct loop *, rtx, rtx *, rtx *));
205 static int find_splittable_regs PARAMS ((const struct loop *,
206 enum unroll_types, rtx, int));
207 static int find_splittable_givs PARAMS ((const struct loop *,
208 struct iv_class *, enum unroll_types,
210 static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
211 static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
212 static int verify_addresses PARAMS ((struct induction *, rtx, int));
213 static rtx remap_split_bivs PARAMS ((rtx));
214 static rtx find_common_reg_term PARAMS ((rtx, rtx));
215 static rtx subtract_reg_term PARAMS ((rtx, rtx));
216 static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
218 /* Try to unroll one loop and split induction variables in the loop.
220 The loop is described by the arguments LOOP and INSN_COUNT.
221 END_INSERT_BEFORE indicates where insns should be added which need
222 to be executed when the loop falls through. STRENGTH_REDUCTION_P
223 indicates whether information generated in the strength reduction
226 This function is intended to be called from within `strength_reduce'
230 unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
233 rtx end_insert_before;
234 int strength_reduce_p;
238 unsigned HOST_WIDE_INT temp;
239 int unroll_number = 1;
240 rtx copy_start, copy_end;
241 rtx insn, sequence, pattern, tem;
242 int max_labelno, max_insnno;
244 struct inline_remap *map;
245 char *local_label = NULL;
247 unsigned int max_local_regnum;
248 unsigned int maxregnum;
252 int splitting_not_safe = 0;
253 enum unroll_types unroll_type = UNROLL_NAIVE;
254 int loop_preconditioned = 0;
256 /* This points to the last real insn in the loop, which should be either
257 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
260 rtx loop_start = loop->start;
261 rtx loop_end = loop->end;
262 struct loop_info *loop_info = LOOP_INFO (loop);
264 /* Don't bother unrolling huge loops. Since the minimum factor is
265 two, loops greater than one half of MAX_UNROLLED_INSNS will never
267 if (insn_count > MAX_UNROLLED_INSNS / 2)
269 if (loop_dump_stream)
270 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
274 /* When emitting debugger info, we can't unroll loops with unequal numbers
275 of block_beg and block_end notes, because that would unbalance the block
276 structure of the function. This can happen as a result of the
277 "if (foo) bar; else break;" optimization in jump.c. */
278 /* ??? Gcc has a general policy that -g is never supposed to change the code
279 that the compiler emits, so we must disable this optimization always,
280 even if debug info is not being output. This is rare, so this should
281 not be a significant performance problem. */
283 if (1 /* write_symbols != NO_DEBUG */)
285 int block_begins = 0;
288 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
290 if (GET_CODE (insn) == NOTE)
292 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
294 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
296 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
297 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
299 /* Note, would be nice to add code to unroll EH
300 regions, but until that time, we punt (don't
301 unroll). For the proper way of doing it, see
302 expand_inline_function. */
304 if (loop_dump_stream)
305 fprintf (loop_dump_stream,
306 "Unrolling failure: cannot unroll EH regions.\n");
312 if (block_begins != block_ends)
314 if (loop_dump_stream)
315 fprintf (loop_dump_stream,
316 "Unrolling failure: Unbalanced block notes.\n");
321 /* Determine type of unroll to perform. Depends on the number of iterations
322 and the size of the loop. */
324 /* If there is no strength reduce info, then set
325 loop_info->n_iterations to zero. This can happen if
326 strength_reduce can't find any bivs in the loop. A value of zero
327 indicates that the number of iterations could not be calculated. */
329 if (! strength_reduce_p)
330 loop_info->n_iterations = 0;
332 if (loop_dump_stream && loop_info->n_iterations > 0)
334 fputs ("Loop unrolling: ", loop_dump_stream);
335 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
336 loop_info->n_iterations);
337 fputs (" iterations.\n", loop_dump_stream);
340 /* Find and save a pointer to the last nonnote insn in the loop. */
342 last_loop_insn = prev_nonnote_insn (loop_end);
344 /* Calculate how many times to unroll the loop. Indicate whether or
345 not the loop is being completely unrolled. */
347 if (loop_info->n_iterations == 1)
349 /* If number of iterations is exactly 1, then eliminate the compare and
350 branch at the end of the loop since they will never be taken.
351 Then return, since no other action is needed here. */
353 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
354 don't do anything. */
356 if (GET_CODE (last_loop_insn) == BARRIER)
358 /* Delete the jump insn. This will delete the barrier also. */
359 delete_insn (PREV_INSN (last_loop_insn));
361 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
364 rtx prev = PREV_INSN (last_loop_insn);
366 delete_insn (last_loop_insn);
368 /* The immediately preceding insn may be a compare which must be
370 if (sets_cc0_p (prev))
375 /* Remove the loop notes since this is no longer a loop. */
377 delete_insn (loop->vtop);
379 delete_insn (loop->cont);
381 delete_insn (loop_start);
383 delete_insn (loop_end);
387 else if (loop_info->n_iterations > 0
388 /* Avoid overflow in the next expression. */
389 && loop_info->n_iterations < MAX_UNROLLED_INSNS
390 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
392 unroll_number = loop_info->n_iterations;
393 unroll_type = UNROLL_COMPLETELY;
395 else if (loop_info->n_iterations > 0)
397 /* Try to factor the number of iterations. Don't bother with the
398 general case, only using 2, 3, 5, and 7 will get 75% of all
399 numbers theoretically, and almost all in practice. */
401 for (i = 0; i < NUM_FACTORS; i++)
402 factors[i].count = 0;
404 temp = loop_info->n_iterations;
405 for (i = NUM_FACTORS - 1; i >= 0; i--)
406 while (temp % factors[i].factor == 0)
409 temp = temp / factors[i].factor;
412 /* Start with the larger factors first so that we generally
413 get lots of unrolling. */
417 for (i = 3; i >= 0; i--)
418 while (factors[i].count--)
420 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
422 unroll_number *= factors[i].factor;
423 temp *= factors[i].factor;
429 /* If we couldn't find any factors, then unroll as in the normal
431 if (unroll_number == 1)
433 if (loop_dump_stream)
434 fprintf (loop_dump_stream,
435 "Loop unrolling: No factors found.\n");
438 unroll_type = UNROLL_MODULO;
442 /* Default case, calculate number of times to unroll loop based on its
444 if (unroll_type == UNROLL_NAIVE)
446 if (8 * insn_count < MAX_UNROLLED_INSNS)
448 else if (4 * insn_count < MAX_UNROLLED_INSNS)
454 /* Now we know how many times to unroll the loop. */
456 if (loop_dump_stream)
457 fprintf (loop_dump_stream,
458 "Unrolling loop %d times.\n", unroll_number);
461 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
463 /* Loops of these types can start with jump down to the exit condition
464 in rare circumstances.
466 Consider a pair of nested loops where the inner loop is part
467 of the exit code for the outer loop.
469 In this case jump.c will not duplicate the exit test for the outer
470 loop, so it will start with a jump to the exit code.
472 Then consider if the inner loop turns out to iterate once and
473 only once. We will end up deleting the jumps associated with
474 the inner loop. However, the loop notes are not removed from
475 the instruction stream.
477 And finally assume that we can compute the number of iterations
480 In this case unroll may want to unroll the outer loop even though
481 it starts with a jump to the outer loop's exit code.
483 We could try to optimize this case, but it hardly seems worth it.
484 Just return without unrolling the loop in such cases. */
487 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
488 insn = NEXT_INSN (insn);
489 if (GET_CODE (insn) == JUMP_INSN)
493 if (unroll_type == UNROLL_COMPLETELY)
495 /* Completely unrolling the loop: Delete the compare and branch at
496 the end (the last two instructions). This delete must done at the
497 very end of loop unrolling, to avoid problems with calls to
498 back_branch_in_range_p, which is called by find_splittable_regs.
499 All increments of splittable bivs/givs are changed to load constant
502 copy_start = loop_start;
504 /* Set insert_before to the instruction immediately after the JUMP_INSN
505 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
506 the loop will be correctly handled by copy_loop_body. */
507 insert_before = NEXT_INSN (last_loop_insn);
509 /* Set copy_end to the insn before the jump at the end of the loop. */
510 if (GET_CODE (last_loop_insn) == BARRIER)
511 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
512 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
514 copy_end = PREV_INSN (last_loop_insn);
516 /* The instruction immediately before the JUMP_INSN may be a compare
517 instruction which we do not want to copy. */
518 if (sets_cc0_p (PREV_INSN (copy_end)))
519 copy_end = PREV_INSN (copy_end);
524 /* We currently can't unroll a loop if it doesn't end with a
525 JUMP_INSN. There would need to be a mechanism that recognizes
526 this case, and then inserts a jump after each loop body, which
527 jumps to after the last loop body. */
528 if (loop_dump_stream)
529 fprintf (loop_dump_stream,
530 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
534 else if (unroll_type == UNROLL_MODULO)
536 /* Partially unrolling the loop: The compare and branch at the end
537 (the last two instructions) must remain. Don't copy the compare
538 and branch instructions at the end of the loop. Insert the unrolled
539 code immediately before the compare/branch at the end so that the
540 code will fall through to them as before. */
542 copy_start = loop_start;
544 /* Set insert_before to the jump insn at the end of the loop.
545 Set copy_end to before the jump insn at the end of the loop. */
546 if (GET_CODE (last_loop_insn) == BARRIER)
548 insert_before = PREV_INSN (last_loop_insn);
549 copy_end = PREV_INSN (insert_before);
551 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
553 insert_before = last_loop_insn;
555 /* The instruction immediately before the JUMP_INSN may be a compare
556 instruction which we do not want to copy or delete. */
557 if (sets_cc0_p (PREV_INSN (insert_before)))
558 insert_before = PREV_INSN (insert_before);
560 copy_end = PREV_INSN (insert_before);
564 /* We currently can't unroll a loop if it doesn't end with a
565 JUMP_INSN. There would need to be a mechanism that recognizes
566 this case, and then inserts a jump after each loop body, which
567 jumps to after the last loop body. */
568 if (loop_dump_stream)
569 fprintf (loop_dump_stream,
570 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
576 /* Normal case: Must copy the compare and branch instructions at the
579 if (GET_CODE (last_loop_insn) == BARRIER)
581 /* Loop ends with an unconditional jump and a barrier.
582 Handle this like above, don't copy jump and barrier.
583 This is not strictly necessary, but doing so prevents generating
584 unconditional jumps to an immediately following label.
586 This will be corrected below if the target of this jump is
587 not the start_label. */
589 insert_before = PREV_INSN (last_loop_insn);
590 copy_end = PREV_INSN (insert_before);
592 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
594 /* Set insert_before to immediately after the JUMP_INSN, so that
595 NOTEs at the end of the loop will be correctly handled by
597 insert_before = NEXT_INSN (last_loop_insn);
598 copy_end = last_loop_insn;
602 /* We currently can't unroll a loop if it doesn't end with a
603 JUMP_INSN. There would need to be a mechanism that recognizes
604 this case, and then inserts a jump after each loop body, which
605 jumps to after the last loop body. */
606 if (loop_dump_stream)
607 fprintf (loop_dump_stream,
608 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
612 /* If copying exit test branches because they can not be eliminated,
613 then must convert the fall through case of the branch to a jump past
614 the end of the loop. Create a label to emit after the loop and save
615 it for later use. Do not use the label after the loop, if any, since
616 it might be used by insns outside the loop, or there might be insns
617 added before it later by final_[bg]iv_value which must be after
618 the real exit label. */
619 exit_label = gen_label_rtx ();
622 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
623 insn = NEXT_INSN (insn);
625 if (GET_CODE (insn) == JUMP_INSN)
627 /* The loop starts with a jump down to the exit condition test.
628 Start copying the loop after the barrier following this
630 copy_start = NEXT_INSN (insn);
632 /* Splitting induction variables doesn't work when the loop is
633 entered via a jump to the bottom, because then we end up doing
634 a comparison against a new register for a split variable, but
635 we did not execute the set insn for the new register because
636 it was skipped over. */
637 splitting_not_safe = 1;
638 if (loop_dump_stream)
639 fprintf (loop_dump_stream,
640 "Splitting not safe, because loop not entered at top.\n");
643 copy_start = loop_start;
646 /* This should always be the first label in the loop. */
647 start_label = NEXT_INSN (copy_start);
648 /* There may be a line number note and/or a loop continue note here. */
649 while (GET_CODE (start_label) == NOTE)
650 start_label = NEXT_INSN (start_label);
651 if (GET_CODE (start_label) != CODE_LABEL)
653 /* This can happen as a result of jump threading. If the first insns in
654 the loop test the same condition as the loop's backward jump, or the
655 opposite condition, then the backward jump will be modified to point
656 to elsewhere, and the loop's start label is deleted.
658 This case currently can not be handled by the loop unrolling code. */
660 if (loop_dump_stream)
661 fprintf (loop_dump_stream,
662 "Unrolling failure: unknown insns between BEG note and loop label.\n");
665 if (LABEL_NAME (start_label))
667 /* The jump optimization pass must have combined the original start label
668 with a named label for a goto. We can't unroll this case because
669 jumps which go to the named label must be handled differently than
670 jumps to the loop start, and it is impossible to differentiate them
672 if (loop_dump_stream)
673 fprintf (loop_dump_stream,
674 "Unrolling failure: loop start label is gone\n");
678 if (unroll_type == UNROLL_NAIVE
679 && GET_CODE (last_loop_insn) == BARRIER
680 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
681 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
683 /* In this case, we must copy the jump and barrier, because they will
684 not be converted to jumps to an immediately following label. */
686 insert_before = NEXT_INSN (last_loop_insn);
687 copy_end = last_loop_insn;
690 if (unroll_type == UNROLL_NAIVE
691 && GET_CODE (last_loop_insn) == JUMP_INSN
692 && start_label != JUMP_LABEL (last_loop_insn))
694 /* ??? The loop ends with a conditional branch that does not branch back
695 to the loop start label. In this case, we must emit an unconditional
696 branch to the loop exit after emitting the final branch.
697 copy_loop_body does not have support for this currently, so we
698 give up. It doesn't seem worthwhile to unroll anyways since
699 unrolling would increase the number of branch instructions
701 if (loop_dump_stream)
702 fprintf (loop_dump_stream,
703 "Unrolling failure: final conditional branch not to loop start\n");
707 /* Allocate a translation table for the labels and insn numbers.
708 They will be filled in as we copy the insns in the loop. */
710 max_labelno = max_label_num ();
711 max_insnno = get_max_uid ();
713 /* Various paths through the unroll code may reach the "egress" label
714 without initializing fields within the map structure.
716 To be safe, we use xcalloc to zero the memory. */
717 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
719 /* Allocate the label map. */
723 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
725 local_label = (char *) xcalloc (max_labelno, sizeof (char));
728 /* Search the loop and mark all local labels, i.e. the ones which have to
729 be distinct labels when copied. For all labels which might be
730 non-local, set their label_map entries to point to themselves.
731 If they happen to be local their label_map entries will be overwritten
732 before the loop body is copied. The label_map entries for local labels
733 will be set to a different value each time the loop body is copied. */
735 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
739 if (GET_CODE (insn) == CODE_LABEL)
740 local_label[CODE_LABEL_NUMBER (insn)] = 1;
741 else if (GET_CODE (insn) == JUMP_INSN)
743 if (JUMP_LABEL (insn))
744 set_label_in_map (map,
745 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
747 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
748 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
750 rtx pat = PATTERN (insn);
751 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
752 int len = XVECLEN (pat, diff_vec_p);
755 for (i = 0; i < len; i++)
757 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
758 set_label_in_map (map,
759 CODE_LABEL_NUMBER (label),
764 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
765 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
769 /* Allocate space for the insn map. */
771 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
773 /* Set this to zero, to indicate that we are doing loop unrolling,
774 not function inlining. */
775 map->inline_target = 0;
777 /* The register and constant maps depend on the number of registers
778 present, so the final maps can't be created until after
779 find_splittable_regs is called. However, they are needed for
780 preconditioning, so we create temporary maps when preconditioning
783 /* The preconditioning code may allocate two new pseudo registers. */
784 maxregnum = max_reg_num ();
786 /* local_regno is only valid for regnos < max_local_regnum. */
787 max_local_regnum = maxregnum;
789 /* Allocate and zero out the splittable_regs and addr_combined_regs
790 arrays. These must be zeroed here because they will be used if
791 loop preconditioning is performed, and must be zero for that case.
793 It is safe to do this here, since the extra registers created by the
794 preconditioning code and find_splittable_regs will never be used
795 to access the splittable_regs[] and addr_combined_regs[] arrays. */
797 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
798 derived_regs = (char *) xcalloc (maxregnum, sizeof (char));
799 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
801 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
802 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
804 /* Mark all local registers, i.e. the ones which are referenced only
806 if (INSN_UID (copy_end) < max_uid_for_loop)
808 int copy_start_luid = INSN_LUID (copy_start);
809 int copy_end_luid = INSN_LUID (copy_end);
811 /* If a register is used in the jump insn, we must not duplicate it
812 since it will also be used outside the loop. */
813 if (GET_CODE (copy_end) == JUMP_INSN)
816 /* If we have a target that uses cc0, then we also must not duplicate
817 the insn that sets cc0 before the jump insn, if one is present. */
819 if (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
823 /* If copy_start points to the NOTE that starts the loop, then we must
824 use the next luid, because invariant pseudo-regs moved out of the loop
825 have their lifetimes modified to start here, but they are not safe
827 if (copy_start == loop_start)
830 /* If a pseudo's lifetime is entirely contained within this loop, then we
831 can use a different pseudo in each unrolled copy of the loop. This
832 results in better code. */
833 /* We must limit the generic test to max_reg_before_loop, because only
834 these pseudo registers have valid regno_first_uid info. */
835 for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r)
836 if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) <= max_uid_for_loop
837 && uid_luid[REGNO_FIRST_UID (r)] >= copy_start_luid
838 && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) <= max_uid_for_loop
839 && uid_luid[REGNO_LAST_UID (r)] <= copy_end_luid)
841 /* However, we must also check for loop-carried dependencies.
842 If the value the pseudo has at the end of iteration X is
843 used by iteration X+1, then we can not use a different pseudo
844 for each unrolled copy of the loop. */
845 /* A pseudo is safe if regno_first_uid is a set, and this
846 set dominates all instructions from regno_first_uid to
848 /* ??? This check is simplistic. We would get better code if
849 this check was more sophisticated. */
850 if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r),
851 copy_start, copy_end))
854 if (loop_dump_stream)
857 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
859 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
863 /* Givs that have been created from multiple biv increments always have
865 for (r = first_increment_giv; r <= last_increment_giv; r++)
868 if (loop_dump_stream)
869 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
873 /* If this loop requires exit tests when unrolled, check to see if we
874 can precondition the loop so as to make the exit tests unnecessary.
875 Just like variable splitting, this is not safe if the loop is entered
876 via a jump to the bottom. Also, can not do this if no strength
877 reduce info, because precondition_loop_p uses this info. */
879 /* Must copy the loop body for preconditioning before the following
880 find_splittable_regs call since that will emit insns which need to
881 be after the preconditioned loop copies, but immediately before the
882 unrolled loop copies. */
884 /* Also, it is not safe to split induction variables for the preconditioned
885 copies of the loop body. If we split induction variables, then the code
886 assumes that each induction variable can be represented as a function
887 of its initial value and the loop iteration number. This is not true
888 in this case, because the last preconditioned copy of the loop body
889 could be any iteration from the first up to the `unroll_number-1'th,
890 depending on the initial value of the iteration variable. Therefore
891 we can not split induction variables here, because we can not calculate
892 their value. Hence, this code must occur before find_splittable_regs
895 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
897 rtx initial_value, final_value, increment;
898 enum machine_mode mode;
900 if (precondition_loop_p (loop,
901 &initial_value, &final_value, &increment,
906 int abs_inc, neg_inc;
908 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
910 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
911 "unroll_loop_precondition");
912 global_const_equiv_varray = map->const_equiv_varray;
914 init_reg_map (map, maxregnum);
916 /* Limit loop unrolling to 4, since this will make 7 copies of
918 if (unroll_number > 4)
921 /* Save the absolute value of the increment, and also whether or
922 not it is negative. */
924 abs_inc = INTVAL (increment);
933 /* Calculate the difference between the final and initial values.
934 Final value may be a (plus (reg x) (const_int 1)) rtx.
935 Let the following cse pass simplify this if initial value is
938 We must copy the final and initial values here to avoid
939 improperly shared rtl. */
941 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
942 copy_rtx (initial_value), NULL_RTX, 0,
945 /* Now calculate (diff % (unroll * abs (increment))) by using an
947 diff = expand_binop (GET_MODE (diff), and_optab, diff,
948 GEN_INT (unroll_number * abs_inc - 1),
949 NULL_RTX, 0, OPTAB_LIB_WIDEN);
951 /* Now emit a sequence of branches to jump to the proper precond
954 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
955 for (i = 0; i < unroll_number; i++)
956 labels[i] = gen_label_rtx ();
958 /* Check for the case where the initial value is greater than or
959 equal to the final value. In that case, we want to execute
960 exactly one loop iteration. The code below will fail for this
961 case. This check does not apply if the loop has a NE
962 comparison at the end. */
964 if (loop_info->comparison_code != NE)
966 emit_cmp_and_jump_insns (initial_value, final_value,
968 NULL_RTX, mode, 0, 0, labels[1]);
969 JUMP_LABEL (get_last_insn ()) = labels[1];
970 LABEL_NUSES (labels[1])++;
973 /* Assuming the unroll_number is 4, and the increment is 2, then
974 for a negative increment: for a positive increment:
975 diff = 0,1 precond 0 diff = 0,7 precond 0
976 diff = 2,3 precond 3 diff = 1,2 precond 1
977 diff = 4,5 precond 2 diff = 3,4 precond 2
978 diff = 6,7 precond 1 diff = 5,6 precond 3 */
980 /* We only need to emit (unroll_number - 1) branches here, the
981 last case just falls through to the following code. */
983 /* ??? This would give better code if we emitted a tree of branches
984 instead of the current linear list of branches. */
986 for (i = 0; i < unroll_number - 1; i++)
989 enum rtx_code cmp_code;
991 /* For negative increments, must invert the constant compared
992 against, except when comparing against zero. */
1000 cmp_const = unroll_number - i;
1009 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
1010 cmp_code, NULL_RTX, mode, 0, 0,
1012 JUMP_LABEL (get_last_insn ()) = labels[i];
1013 LABEL_NUSES (labels[i])++;
1016 /* If the increment is greater than one, then we need another branch,
1017 to handle other cases equivalent to 0. */
1019 /* ??? This should be merged into the code above somehow to help
1020 simplify the code here, and reduce the number of branches emitted.
1021 For the negative increment case, the branch here could easily
1022 be merged with the `0' case branch above. For the positive
1023 increment case, it is not clear how this can be simplified. */
1028 enum rtx_code cmp_code;
1032 cmp_const = abs_inc - 1;
1037 cmp_const = abs_inc * (unroll_number - 1) + 1;
1041 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1042 NULL_RTX, mode, 0, 0, labels[0]);
1043 JUMP_LABEL (get_last_insn ()) = labels[0];
1044 LABEL_NUSES (labels[0])++;
1047 sequence = gen_sequence ();
1049 emit_insn_before (sequence, loop_start);
1051 /* Only the last copy of the loop body here needs the exit
1052 test, so set copy_end to exclude the compare/branch here,
1053 and then reset it inside the loop when get to the last
1056 if (GET_CODE (last_loop_insn) == BARRIER)
1057 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1058 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1060 copy_end = PREV_INSN (last_loop_insn);
1062 /* The immediately preceding insn may be a compare which we do not
1064 if (sets_cc0_p (PREV_INSN (copy_end)))
1065 copy_end = PREV_INSN (copy_end);
1071 for (i = 1; i < unroll_number; i++)
1073 emit_label_after (labels[unroll_number - i],
1074 PREV_INSN (loop_start));
1076 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1077 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1078 (VARRAY_SIZE (map->const_equiv_varray)
1079 * sizeof (struct const_equiv_data)));
1082 for (j = 0; j < max_labelno; j++)
1084 set_label_in_map (map, j, gen_label_rtx ());
1086 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1090 = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1091 record_base_value (REGNO (map->reg_map[r]),
1092 regno_reg_rtx[r], 0);
1094 /* The last copy needs the compare/branch insns at the end,
1095 so reset copy_end here if the loop ends with a conditional
1098 if (i == unroll_number - 1)
1100 if (GET_CODE (last_loop_insn) == BARRIER)
1101 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1103 copy_end = last_loop_insn;
1106 /* None of the copies are the `last_iteration', so just
1107 pass zero for that parameter. */
1108 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1109 unroll_type, start_label, loop_end,
1110 loop_start, copy_end);
1112 emit_label_after (labels[0], PREV_INSN (loop_start));
1114 if (GET_CODE (last_loop_insn) == BARRIER)
1116 insert_before = PREV_INSN (last_loop_insn);
1117 copy_end = PREV_INSN (insert_before);
1121 insert_before = last_loop_insn;
1123 /* The instruction immediately before the JUMP_INSN may be a compare
1124 instruction which we do not want to copy or delete. */
1125 if (sets_cc0_p (PREV_INSN (insert_before)))
1126 insert_before = PREV_INSN (insert_before);
1128 copy_end = PREV_INSN (insert_before);
1131 /* Set unroll type to MODULO now. */
1132 unroll_type = UNROLL_MODULO;
1133 loop_preconditioned = 1;
1140 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1141 the loop unless all loops are being unrolled. */
1142 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1144 if (loop_dump_stream)
1145 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1149 /* At this point, we are guaranteed to unroll the loop. */
1151 /* Keep track of the unroll factor for the loop. */
1152 loop_info->unroll_number = unroll_number;
1154 /* For each biv and giv, determine whether it can be safely split into
1155 a different variable for each unrolled copy of the loop body.
1156 We precalculate and save this info here, since computing it is
1159 Do this before deleting any instructions from the loop, so that
1160 back_branch_in_range_p will work correctly. */
1162 if (splitting_not_safe)
1165 temp = find_splittable_regs (loop, unroll_type,
1166 end_insert_before, unroll_number);
1168 /* find_splittable_regs may have created some new registers, so must
1169 reallocate the reg_map with the new larger size, and must realloc
1170 the constant maps also. */
1172 maxregnum = max_reg_num ();
1173 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1175 init_reg_map (map, maxregnum);
1177 if (map->const_equiv_varray == 0)
1178 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1179 maxregnum + temp * unroll_number * 2,
1181 global_const_equiv_varray = map->const_equiv_varray;
1183 /* Search the list of bivs and givs to find ones which need to be remapped
1184 when split, and set their reg_map entry appropriately. */
1186 for (bl = loop_iv_list; bl; bl = bl->next)
1188 if (REGNO (bl->biv->src_reg) != bl->regno)
1189 map->reg_map[bl->regno] = bl->biv->src_reg;
1191 /* Currently, non-reduced/final-value givs are never split. */
1192 for (v = bl->giv; v; v = v->next_iv)
1193 if (REGNO (v->src_reg) != bl->regno)
1194 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1198 /* Use our current register alignment and pointer flags. */
1199 map->regno_pointer_flag = cfun->emit->regno_pointer_flag;
1200 map->regno_pointer_align = cfun->emit->regno_pointer_align;
1202 /* If the loop is being partially unrolled, and the iteration variables
1203 are being split, and are being renamed for the split, then must fix up
1204 the compare/jump instruction at the end of the loop to refer to the new
1205 registers. This compare isn't copied, so the registers used in it
1206 will never be replaced if it isn't done here. */
1208 if (unroll_type == UNROLL_MODULO)
1210 insn = NEXT_INSN (copy_end);
1211 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1212 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1215 /* For unroll_number times, make a copy of each instruction
1216 between copy_start and copy_end, and insert these new instructions
1217 before the end of the loop. */
1219 for (i = 0; i < unroll_number; i++)
1221 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1222 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1223 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1226 for (j = 0; j < max_labelno; j++)
1228 set_label_in_map (map, j, gen_label_rtx ());
1230 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1233 map->reg_map[r] = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1234 record_base_value (REGNO (map->reg_map[r]),
1235 regno_reg_rtx[r], 0);
1238 /* If loop starts with a branch to the test, then fix it so that
1239 it points to the test of the first unrolled copy of the loop. */
1240 if (i == 0 && loop_start != copy_start)
1242 insn = PREV_INSN (copy_start);
1243 pattern = PATTERN (insn);
1245 tem = get_label_from_map (map,
1247 (XEXP (SET_SRC (pattern), 0)));
1248 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1250 /* Set the jump label so that it can be used by later loop unrolling
1252 JUMP_LABEL (insn) = tem;
1253 LABEL_NUSES (tem)++;
1256 copy_loop_body (copy_start, copy_end, map, exit_label,
1257 i == unroll_number - 1, unroll_type, start_label,
1258 loop_end, insert_before, insert_before);
1261 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1262 insn to be deleted. This prevents any runaway delete_insn call from
1263 more insns that it should, as it always stops at a CODE_LABEL. */
1265 /* Delete the compare and branch at the end of the loop if completely
1266 unrolling the loop. Deleting the backward branch at the end also
1267 deletes the code label at the start of the loop. This is done at
1268 the very end to avoid problems with back_branch_in_range_p. */
1270 if (unroll_type == UNROLL_COMPLETELY)
1271 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1273 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1275 /* Delete all of the original loop instructions. Don't delete the
1276 LOOP_BEG note, or the first code label in the loop. */
1278 insn = NEXT_INSN (copy_start);
1279 while (insn != safety_label)
1281 /* ??? Don't delete named code labels. They will be deleted when the
1282 jump that references them is deleted. Otherwise, we end up deleting
1283 them twice, which causes them to completely disappear instead of turn
1284 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1285 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1286 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1287 associated LABEL_DECL to point to one of the new label instances. */
1288 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1289 if (insn != start_label
1290 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1291 && ! (GET_CODE (insn) == NOTE
1292 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1293 insn = delete_insn (insn);
1295 insn = NEXT_INSN (insn);
1298 /* Can now delete the 'safety' label emitted to protect us from runaway
1299 delete_insn calls. */
1300 if (INSN_DELETED_P (safety_label))
1302 delete_insn (safety_label);
1304 /* If exit_label exists, emit it after the loop. Doing the emit here
1305 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1306 This is needed so that mostly_true_jump in reorg.c will treat jumps
1307 to this loop end label correctly, i.e. predict that they are usually
1310 emit_label_after (exit_label, loop_end);
1313 if (unroll_type == UNROLL_COMPLETELY)
1315 /* Remove the loop notes since this is no longer a loop. */
1317 delete_insn (loop->vtop);
1319 delete_insn (loop->cont);
1321 delete_insn (loop_start);
1323 delete_insn (loop_end);
1326 if (map->const_equiv_varray)
1327 VARRAY_FREE (map->const_equiv_varray);
1330 free (map->label_map);
1333 free (map->insn_map);
1334 free (splittable_regs);
1335 free (derived_regs);
1336 free (splittable_regs_updates);
1337 free (addr_combined_regs);
1340 free (map->reg_map);
1344 /* Return true if the loop can be safely, and profitably, preconditioned
1345 so that the unrolled copies of the loop body don't need exit tests.
1347 This only works if final_value, initial_value and increment can be
1348 determined, and if increment is a constant power of 2.
1349 If increment is not a power of 2, then the preconditioning modulo
1350 operation would require a real modulo instead of a boolean AND, and this
1351 is not considered `profitable'. */
1353 /* ??? If the loop is known to be executed very many times, or the machine
1354 has a very cheap divide instruction, then preconditioning is a win even
1355 when the increment is not a power of 2. Use RTX_COST to compute
1356 whether divide is cheap.
1357 ??? A divide by constant doesn't actually need a divide, look at
1358 expand_divmod. The reduced cost of this optimized modulo is not
1359 reflected in RTX_COST. */
1362 precondition_loop_p (loop, initial_value, final_value, increment, mode)
1363 const struct loop *loop;
1364 rtx *initial_value, *final_value, *increment;
1365 enum machine_mode *mode;
1367 rtx loop_start = loop->start;
1368 struct loop_info *loop_info = LOOP_INFO (loop);
1370 if (loop_info->n_iterations > 0)
1372 *initial_value = const0_rtx;
1373 *increment = const1_rtx;
1374 *final_value = GEN_INT (loop_info->n_iterations);
1377 if (loop_dump_stream)
1379 fputs ("Preconditioning: Success, number of iterations known, ",
1381 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1382 loop_info->n_iterations);
1383 fputs (".\n", loop_dump_stream);
1388 if (loop_info->initial_value == 0)
1390 if (loop_dump_stream)
1391 fprintf (loop_dump_stream,
1392 "Preconditioning: Could not find initial value.\n");
1395 else if (loop_info->increment == 0)
1397 if (loop_dump_stream)
1398 fprintf (loop_dump_stream,
1399 "Preconditioning: Could not find increment value.\n");
1402 else if (GET_CODE (loop_info->increment) != CONST_INT)
1404 if (loop_dump_stream)
1405 fprintf (loop_dump_stream,
1406 "Preconditioning: Increment not a constant.\n");
1409 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1410 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1412 if (loop_dump_stream)
1413 fprintf (loop_dump_stream,
1414 "Preconditioning: Increment not a constant power of 2.\n");
1418 /* Unsigned_compare and compare_dir can be ignored here, since they do
1419 not matter for preconditioning. */
1421 if (loop_info->final_value == 0)
1423 if (loop_dump_stream)
1424 fprintf (loop_dump_stream,
1425 "Preconditioning: EQ comparison loop.\n");
1429 /* Must ensure that final_value is invariant, so call
1430 loop_invariant_p to check. Before doing so, must check regno
1431 against max_reg_before_loop to make sure that the register is in
1432 the range covered by loop_invariant_p. If it isn't, then it is
1433 most likely a biv/giv which by definition are not invariant. */
1434 if ((GET_CODE (loop_info->final_value) == REG
1435 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1436 || (GET_CODE (loop_info->final_value) == PLUS
1437 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1438 || ! loop_invariant_p (loop, loop_info->final_value))
1440 if (loop_dump_stream)
1441 fprintf (loop_dump_stream,
1442 "Preconditioning: Final value not invariant.\n");
1446 /* Fail for floating point values, since the caller of this function
1447 does not have code to deal with them. */
1448 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1449 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1451 if (loop_dump_stream)
1452 fprintf (loop_dump_stream,
1453 "Preconditioning: Floating point final or initial value.\n");
1457 /* Fail if loop_info->iteration_var is not live before loop_start,
1458 since we need to test its value in the preconditioning code. */
1460 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1461 > INSN_LUID (loop_start))
1463 if (loop_dump_stream)
1464 fprintf (loop_dump_stream,
1465 "Preconditioning: Iteration var not live before loop start.\n");
1469 /* Note that iteration_info biases the initial value for GIV iterators
1470 such as "while (i-- > 0)" so that we can calculate the number of
1471 iterations just like for BIV iterators.
1473 Also note that the absolute values of initial_value and
1474 final_value are unimportant as only their difference is used for
1475 calculating the number of loop iterations. */
1476 *initial_value = loop_info->initial_value;
1477 *increment = loop_info->increment;
1478 *final_value = loop_info->final_value;
1480 /* Decide what mode to do these calculations in. Choose the larger
1481 of final_value's mode and initial_value's mode, or a full-word if
1482 both are constants. */
1483 *mode = GET_MODE (*final_value);
1484 if (*mode == VOIDmode)
1486 *mode = GET_MODE (*initial_value);
1487 if (*mode == VOIDmode)
1490 else if (*mode != GET_MODE (*initial_value)
1491 && (GET_MODE_SIZE (*mode)
1492 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1493 *mode = GET_MODE (*initial_value);
1496 if (loop_dump_stream)
1497 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1502 /* All pseudo-registers must be mapped to themselves. Two hard registers
1503 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1504 REGNUM, to avoid function-inlining specific conversions of these
1505 registers. All other hard regs can not be mapped because they may be
1510 init_reg_map (map, maxregnum)
1511 struct inline_remap *map;
1516 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1517 map->reg_map[i] = regno_reg_rtx[i];
1518 /* Just clear the rest of the entries. */
1519 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1520 map->reg_map[i] = 0;
1522 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1523 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1524 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1525 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1528 /* Strength-reduction will often emit code for optimized biv/givs which
1529 calculates their value in a temporary register, and then copies the result
1530 to the iv. This procedure reconstructs the pattern computing the iv;
1531 verifying that all operands are of the proper form.
1533 PATTERN must be the result of single_set.
1534 The return value is the amount that the giv is incremented by. */
1537 calculate_giv_inc (pattern, src_insn, regno)
1538 rtx pattern, src_insn;
1542 rtx increment_total = 0;
1546 /* Verify that we have an increment insn here. First check for a plus
1547 as the set source. */
1548 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1550 /* SR sometimes computes the new giv value in a temp, then copies it
1552 src_insn = PREV_INSN (src_insn);
1553 pattern = PATTERN (src_insn);
1554 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1557 /* The last insn emitted is not needed, so delete it to avoid confusing
1558 the second cse pass. This insn sets the giv unnecessarily. */
1559 delete_insn (get_last_insn ());
1562 /* Verify that we have a constant as the second operand of the plus. */
1563 increment = XEXP (SET_SRC (pattern), 1);
1564 if (GET_CODE (increment) != CONST_INT)
1566 /* SR sometimes puts the constant in a register, especially if it is
1567 too big to be an add immed operand. */
1568 src_insn = PREV_INSN (src_insn);
1569 increment = SET_SRC (PATTERN (src_insn));
1571 /* SR may have used LO_SUM to compute the constant if it is too large
1572 for a load immed operand. In this case, the constant is in operand
1573 one of the LO_SUM rtx. */
1574 if (GET_CODE (increment) == LO_SUM)
1575 increment = XEXP (increment, 1);
1577 /* Some ports store large constants in memory and add a REG_EQUAL
1578 note to the store insn. */
1579 else if (GET_CODE (increment) == MEM)
1581 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1583 increment = XEXP (note, 0);
1586 else if (GET_CODE (increment) == IOR
1587 || GET_CODE (increment) == ASHIFT
1588 || GET_CODE (increment) == PLUS)
1590 /* The rs6000 port loads some constants with IOR.
1591 The alpha port loads some constants with ASHIFT and PLUS. */
1592 rtx second_part = XEXP (increment, 1);
1593 enum rtx_code code = GET_CODE (increment);
1595 src_insn = PREV_INSN (src_insn);
1596 increment = SET_SRC (PATTERN (src_insn));
1597 /* Don't need the last insn anymore. */
1598 delete_insn (get_last_insn ());
1600 if (GET_CODE (second_part) != CONST_INT
1601 || GET_CODE (increment) != CONST_INT)
1605 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1606 else if (code == PLUS)
1607 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1609 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1612 if (GET_CODE (increment) != CONST_INT)
1615 /* The insn loading the constant into a register is no longer needed,
1617 delete_insn (get_last_insn ());
1620 if (increment_total)
1621 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1623 increment_total = increment;
1625 /* Check that the source register is the same as the register we expected
1626 to see as the source. If not, something is seriously wrong. */
1627 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1628 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1630 /* Some machines (e.g. the romp), may emit two add instructions for
1631 certain constants, so lets try looking for another add immediately
1632 before this one if we have only seen one add insn so far. */
1638 src_insn = PREV_INSN (src_insn);
1639 pattern = PATTERN (src_insn);
1641 delete_insn (get_last_insn ());
1649 return increment_total;
1652 /* Copy REG_NOTES, except for insn references, because not all insn_map
1653 entries are valid yet. We do need to copy registers now though, because
1654 the reg_map entries can change during copying. */
1657 initial_reg_note_copy (notes, map)
1659 struct inline_remap *map;
1666 copy = rtx_alloc (GET_CODE (notes));
1667 PUT_MODE (copy, GET_MODE (notes));
1669 if (GET_CODE (notes) == EXPR_LIST)
1670 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1671 else if (GET_CODE (notes) == INSN_LIST)
1672 /* Don't substitute for these yet. */
1673 XEXP (copy, 0) = XEXP (notes, 0);
1677 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1682 /* Fixup insn references in copied REG_NOTES. */
1685 final_reg_note_copy (notes, map)
1687 struct inline_remap *map;
1691 for (note = notes; note; note = XEXP (note, 1))
1692 if (GET_CODE (note) == INSN_LIST)
1693 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1696 /* Copy each instruction in the loop, substituting from map as appropriate.
1697 This is very similar to a loop in expand_inline_function. */
1700 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1701 unroll_type, start_label, loop_end, insert_before,
1703 rtx copy_start, copy_end;
1704 struct inline_remap *map;
1707 enum unroll_types unroll_type;
1708 rtx start_label, loop_end, insert_before, copy_notes_from;
1711 rtx set, tem, copy = NULL_RTX;
1712 int dest_reg_was_split, i;
1716 rtx final_label = 0;
1717 rtx giv_inc, giv_dest_reg, giv_src_reg;
1719 /* If this isn't the last iteration, then map any references to the
1720 start_label to final_label. Final label will then be emitted immediately
1721 after the end of this loop body if it was ever used.
1723 If this is the last iteration, then map references to the start_label
1725 if (! last_iteration)
1727 final_label = gen_label_rtx ();
1728 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1732 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1736 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1737 Else gen_sequence could return a raw pattern for a jump which we pass
1738 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1739 a variety of losing behaviors later. */
1740 emit_note (0, NOTE_INSN_DELETED);
1745 insn = NEXT_INSN (insn);
1747 map->orig_asm_operands_vector = 0;
1749 switch (GET_CODE (insn))
1752 pattern = PATTERN (insn);
1756 /* Check to see if this is a giv that has been combined with
1757 some split address givs. (Combined in the sense that
1758 `combine_givs' in loop.c has put two givs in the same register.)
1759 In this case, we must search all givs based on the same biv to
1760 find the address givs. Then split the address givs.
1761 Do this before splitting the giv, since that may map the
1762 SET_DEST to a new register. */
1764 if ((set = single_set (insn))
1765 && GET_CODE (SET_DEST (set)) == REG
1766 && addr_combined_regs[REGNO (SET_DEST (set))])
1768 struct iv_class *bl;
1769 struct induction *v, *tv;
1770 unsigned int regno = REGNO (SET_DEST (set));
1772 v = addr_combined_regs[REGNO (SET_DEST (set))];
1773 bl = reg_biv_class[REGNO (v->src_reg)];
1775 /* Although the giv_inc amount is not needed here, we must call
1776 calculate_giv_inc here since it might try to delete the
1777 last insn emitted. If we wait until later to call it,
1778 we might accidentally delete insns generated immediately
1779 below by emit_unrolled_add. */
1781 if (! derived_regs[regno])
1782 giv_inc = calculate_giv_inc (set, insn, regno);
1784 /* Now find all address giv's that were combined with this
1786 for (tv = bl->giv; tv; tv = tv->next_iv)
1787 if (tv->giv_type == DEST_ADDR && tv->same == v)
1791 /* If this DEST_ADDR giv was not split, then ignore it. */
1792 if (*tv->location != tv->dest_reg)
1795 /* Scale this_giv_inc if the multiplicative factors of
1796 the two givs are different. */
1797 this_giv_inc = INTVAL (giv_inc);
1798 if (tv->mult_val != v->mult_val)
1799 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1800 * INTVAL (tv->mult_val));
1802 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1803 *tv->location = tv->dest_reg;
1805 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1807 /* Must emit an insn to increment the split address
1808 giv. Add in the const_adjust field in case there
1809 was a constant eliminated from the address. */
1810 rtx value, dest_reg;
1812 /* tv->dest_reg will be either a bare register,
1813 or else a register plus a constant. */
1814 if (GET_CODE (tv->dest_reg) == REG)
1815 dest_reg = tv->dest_reg;
1817 dest_reg = XEXP (tv->dest_reg, 0);
1819 /* Check for shared address givs, and avoid
1820 incrementing the shared pseudo reg more than
1822 if (! tv->same_insn && ! tv->shared)
1824 /* tv->dest_reg may actually be a (PLUS (REG)
1825 (CONST)) here, so we must call plus_constant
1826 to add the const_adjust amount before calling
1827 emit_unrolled_add below. */
1828 value = plus_constant (tv->dest_reg,
1831 if (GET_CODE (value) == PLUS)
1833 /* The constant could be too large for an add
1834 immediate, so can't directly emit an insn
1836 emit_unrolled_add (dest_reg, XEXP (value, 0),
1841 /* Reset the giv to be just the register again, in case
1842 it is used after the set we have just emitted.
1843 We must subtract the const_adjust factor added in
1845 tv->dest_reg = plus_constant (dest_reg,
1846 - tv->const_adjust);
1847 *tv->location = tv->dest_reg;
1852 /* If this is a setting of a splittable variable, then determine
1853 how to split the variable, create a new set based on this split,
1854 and set up the reg_map so that later uses of the variable will
1855 use the new split variable. */
1857 dest_reg_was_split = 0;
1859 if ((set = single_set (insn))
1860 && GET_CODE (SET_DEST (set)) == REG
1861 && splittable_regs[REGNO (SET_DEST (set))])
1863 unsigned int regno = REGNO (SET_DEST (set));
1864 unsigned int src_regno;
1866 dest_reg_was_split = 1;
1868 giv_dest_reg = SET_DEST (set);
1869 if (derived_regs[regno])
1871 /* ??? This relies on SET_SRC (SET) to be of
1872 the form (plus (reg) (const_int)), and thus
1873 forces recombine_givs to restrict the kind
1874 of giv derivations it does before unrolling. */
1875 giv_src_reg = XEXP (SET_SRC (set), 0);
1876 giv_inc = XEXP (SET_SRC (set), 1);
1880 giv_src_reg = giv_dest_reg;
1881 /* Compute the increment value for the giv, if it wasn't
1882 already computed above. */
1884 giv_inc = calculate_giv_inc (set, insn, regno);
1886 src_regno = REGNO (giv_src_reg);
1888 if (unroll_type == UNROLL_COMPLETELY)
1890 /* Completely unrolling the loop. Set the induction
1891 variable to a known constant value. */
1893 /* The value in splittable_regs may be an invariant
1894 value, so we must use plus_constant here. */
1895 splittable_regs[regno]
1896 = plus_constant (splittable_regs[src_regno],
1899 if (GET_CODE (splittable_regs[regno]) == PLUS)
1901 giv_src_reg = XEXP (splittable_regs[regno], 0);
1902 giv_inc = XEXP (splittable_regs[regno], 1);
1906 /* The splittable_regs value must be a REG or a
1907 CONST_INT, so put the entire value in the giv_src_reg
1909 giv_src_reg = splittable_regs[regno];
1910 giv_inc = const0_rtx;
1915 /* Partially unrolling loop. Create a new pseudo
1916 register for the iteration variable, and set it to
1917 be a constant plus the original register. Except
1918 on the last iteration, when the result has to
1919 go back into the original iteration var register. */
1921 /* Handle bivs which must be mapped to a new register
1922 when split. This happens for bivs which need their
1923 final value set before loop entry. The new register
1924 for the biv was stored in the biv's first struct
1925 induction entry by find_splittable_regs. */
1927 if (regno < max_reg_before_loop
1928 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1930 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1931 giv_dest_reg = giv_src_reg;
1935 /* If non-reduced/final-value givs were split, then
1936 this would have to remap those givs also. See
1937 find_splittable_regs. */
1940 splittable_regs[regno]
1941 = GEN_INT (INTVAL (giv_inc)
1942 + INTVAL (splittable_regs[src_regno]));
1943 giv_inc = splittable_regs[regno];
1945 /* Now split the induction variable by changing the dest
1946 of this insn to a new register, and setting its
1947 reg_map entry to point to this new register.
1949 If this is the last iteration, and this is the last insn
1950 that will update the iv, then reuse the original dest,
1951 to ensure that the iv will have the proper value when
1952 the loop exits or repeats.
1954 Using splittable_regs_updates here like this is safe,
1955 because it can only be greater than one if all
1956 instructions modifying the iv are always executed in
1959 if (! last_iteration
1960 || (splittable_regs_updates[regno]-- != 1))
1962 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1964 map->reg_map[regno] = tem;
1965 record_base_value (REGNO (tem),
1966 giv_inc == const0_rtx
1968 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1969 giv_src_reg, giv_inc),
1973 map->reg_map[regno] = giv_src_reg;
1976 /* The constant being added could be too large for an add
1977 immediate, so can't directly emit an insn here. */
1978 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1979 copy = get_last_insn ();
1980 pattern = PATTERN (copy);
1984 pattern = copy_rtx_and_substitute (pattern, map, 0);
1985 copy = emit_insn (pattern);
1987 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1990 /* If this insn is setting CC0, it may need to look at
1991 the insn that uses CC0 to see what type of insn it is.
1992 In that case, the call to recog via validate_change will
1993 fail. So don't substitute constants here. Instead,
1994 do it when we emit the following insn.
1996 For example, see the pyr.md file. That machine has signed and
1997 unsigned compares. The compare patterns must check the
1998 following branch insn to see which what kind of compare to
2001 If the previous insn set CC0, substitute constants on it as
2003 if (sets_cc0_p (PATTERN (copy)) != 0)
2008 try_constants (cc0_insn, map);
2010 try_constants (copy, map);
2013 try_constants (copy, map);
2016 /* Make split induction variable constants `permanent' since we
2017 know there are no backward branches across iteration variable
2018 settings which would invalidate this. */
2019 if (dest_reg_was_split)
2021 int regno = REGNO (SET_DEST (set));
2023 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
2024 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
2026 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
2031 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2032 copy = emit_jump_insn (pattern);
2033 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2035 if (JUMP_LABEL (insn) == start_label && insn == copy_end
2036 && ! last_iteration)
2038 /* This is a branch to the beginning of the loop; this is the
2039 last insn being copied; and this is not the last iteration.
2040 In this case, we want to change the original fall through
2041 case to be a branch past the end of the loop, and the
2042 original jump label case to fall_through. */
2044 if (invert_exp (pattern, copy))
2046 if (! redirect_exp (&pattern,
2047 get_label_from_map (map,
2049 (JUMP_LABEL (insn))),
2056 rtx lab = gen_label_rtx ();
2057 /* Can't do it by reversing the jump (probably because we
2058 couldn't reverse the conditions), so emit a new
2059 jump_insn after COPY, and redirect the jump around
2061 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2062 jmp = emit_barrier_after (jmp);
2063 emit_label_after (lab, jmp);
2064 LABEL_NUSES (lab) = 0;
2065 if (! redirect_exp (&pattern,
2066 get_label_from_map (map,
2068 (JUMP_LABEL (insn))),
2076 try_constants (cc0_insn, map);
2079 try_constants (copy, map);
2081 /* Set the jump label of COPY correctly to avoid problems with
2082 later passes of unroll_loop, if INSN had jump label set. */
2083 if (JUMP_LABEL (insn))
2087 /* Can't use the label_map for every insn, since this may be
2088 the backward branch, and hence the label was not mapped. */
2089 if ((set = single_set (copy)))
2091 tem = SET_SRC (set);
2092 if (GET_CODE (tem) == LABEL_REF)
2093 label = XEXP (tem, 0);
2094 else if (GET_CODE (tem) == IF_THEN_ELSE)
2096 if (XEXP (tem, 1) != pc_rtx)
2097 label = XEXP (XEXP (tem, 1), 0);
2099 label = XEXP (XEXP (tem, 2), 0);
2103 if (label && GET_CODE (label) == CODE_LABEL)
2104 JUMP_LABEL (copy) = label;
2107 /* An unrecognizable jump insn, probably the entry jump
2108 for a switch statement. This label must have been mapped,
2109 so just use the label_map to get the new jump label. */
2111 = get_label_from_map (map,
2112 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2115 /* If this is a non-local jump, then must increase the label
2116 use count so that the label will not be deleted when the
2117 original jump is deleted. */
2118 LABEL_NUSES (JUMP_LABEL (copy))++;
2120 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2121 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2123 rtx pat = PATTERN (copy);
2124 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2125 int len = XVECLEN (pat, diff_vec_p);
2128 for (i = 0; i < len; i++)
2129 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2132 /* If this used to be a conditional jump insn but whose branch
2133 direction is now known, we must do something special. */
2134 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2137 /* If the previous insn set cc0 for us, delete it. */
2138 if (sets_cc0_p (PREV_INSN (copy)))
2139 delete_insn (PREV_INSN (copy));
2142 /* If this is now a no-op, delete it. */
2143 if (map->last_pc_value == pc_rtx)
2145 /* Don't let delete_insn delete the label referenced here,
2146 because we might possibly need it later for some other
2147 instruction in the loop. */
2148 if (JUMP_LABEL (copy))
2149 LABEL_NUSES (JUMP_LABEL (copy))++;
2151 if (JUMP_LABEL (copy))
2152 LABEL_NUSES (JUMP_LABEL (copy))--;
2156 /* Otherwise, this is unconditional jump so we must put a
2157 BARRIER after it. We could do some dead code elimination
2158 here, but jump.c will do it just as well. */
2164 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2165 copy = emit_call_insn (pattern);
2166 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2168 /* Because the USAGE information potentially contains objects other
2169 than hard registers, we need to copy it. */
2170 CALL_INSN_FUNCTION_USAGE (copy)
2171 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2176 try_constants (cc0_insn, map);
2179 try_constants (copy, map);
2181 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2182 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2183 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2187 /* If this is the loop start label, then we don't need to emit a
2188 copy of this label since no one will use it. */
2190 if (insn != start_label)
2192 copy = emit_label (get_label_from_map (map,
2193 CODE_LABEL_NUMBER (insn)));
2199 copy = emit_barrier ();
2203 /* VTOP and CONT notes are valid only before the loop exit test.
2204 If placed anywhere else, loop may generate bad code. */
2205 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2206 the associated rtl. We do not want to share the structure in
2209 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2210 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED_LABEL
2211 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2212 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2213 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2214 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2215 copy = emit_note (NOTE_SOURCE_FILE (insn),
2216 NOTE_LINE_NUMBER (insn));
2225 map->insn_map[INSN_UID (insn)] = copy;
2227 while (insn != copy_end);
2229 /* Now finish coping the REG_NOTES. */
2233 insn = NEXT_INSN (insn);
2234 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2235 || GET_CODE (insn) == CALL_INSN)
2236 && map->insn_map[INSN_UID (insn)])
2237 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2239 while (insn != copy_end);
2241 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2242 each of these notes here, since there may be some important ones, such as
2243 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2244 iteration, because the original notes won't be deleted.
2246 We can't use insert_before here, because when from preconditioning,
2247 insert_before points before the loop. We can't use copy_end, because
2248 there may be insns already inserted after it (which we don't want to
2249 copy) when not from preconditioning code. */
2251 if (! last_iteration)
2253 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2255 /* VTOP notes are valid only before the loop exit test.
2256 If placed anywhere else, loop may generate bad code.
2257 There is no need to test for NOTE_INSN_LOOP_CONT notes
2258 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2259 instructions before the last insn in the loop, and if the
2260 end test is that short, there will be a VTOP note between
2261 the CONT note and the test. */
2262 if (GET_CODE (insn) == NOTE
2263 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2264 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2265 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2266 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2270 if (final_label && LABEL_NUSES (final_label) > 0)
2271 emit_label (final_label);
2273 tem = gen_sequence ();
2275 emit_insn_before (tem, insert_before);
2278 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2279 emitted. This will correctly handle the case where the increment value
2280 won't fit in the immediate field of a PLUS insns. */
2283 emit_unrolled_add (dest_reg, src_reg, increment)
2284 rtx dest_reg, src_reg, increment;
2288 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2289 dest_reg, 0, OPTAB_LIB_WIDEN);
2291 if (dest_reg != result)
2292 emit_move_insn (dest_reg, result);
2295 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2296 is a backward branch in that range that branches to somewhere between
2297 LOOP->START and INSN. Returns 0 otherwise. */
2299 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2300 In practice, this is not a problem, because this function is seldom called,
2301 and uses a negligible amount of CPU time on average. */
2304 back_branch_in_range_p (loop, insn)
2305 const struct loop *loop;
2308 rtx p, q, target_insn;
2309 rtx loop_start = loop->start;
2310 rtx loop_end = loop->end;
2311 rtx orig_loop_end = loop->end;
2313 /* Stop before we get to the backward branch at the end of the loop. */
2314 loop_end = prev_nonnote_insn (loop_end);
2315 if (GET_CODE (loop_end) == BARRIER)
2316 loop_end = PREV_INSN (loop_end);
2318 /* Check in case insn has been deleted, search forward for first non
2319 deleted insn following it. */
2320 while (INSN_DELETED_P (insn))
2321 insn = NEXT_INSN (insn);
2323 /* Check for the case where insn is the last insn in the loop. Deal
2324 with the case where INSN was a deleted loop test insn, in which case
2325 it will now be the NOTE_LOOP_END. */
2326 if (insn == loop_end || insn == orig_loop_end)
2329 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2331 if (GET_CODE (p) == JUMP_INSN)
2333 target_insn = JUMP_LABEL (p);
2335 /* Search from loop_start to insn, to see if one of them is
2336 the target_insn. We can't use INSN_LUID comparisons here,
2337 since insn may not have an LUID entry. */
2338 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2339 if (q == target_insn)
2347 /* Try to generate the simplest rtx for the expression
2348 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2352 fold_rtx_mult_add (mult1, mult2, add1, mode)
2353 rtx mult1, mult2, add1;
2354 enum machine_mode mode;
2359 /* The modes must all be the same. This should always be true. For now,
2360 check to make sure. */
2361 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2362 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2363 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2366 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2367 will be a constant. */
2368 if (GET_CODE (mult1) == CONST_INT)
2375 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2377 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2379 /* Again, put the constant second. */
2380 if (GET_CODE (add1) == CONST_INT)
2387 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2389 result = gen_rtx_PLUS (mode, add1, mult_res);
2394 /* Searches the list of induction struct's for the biv BL, to try to calculate
2395 the total increment value for one iteration of the loop as a constant.
2397 Returns the increment value as an rtx, simplified as much as possible,
2398 if it can be calculated. Otherwise, returns 0. */
2401 biv_total_increment (bl)
2402 struct iv_class *bl;
2404 struct induction *v;
2407 /* For increment, must check every instruction that sets it. Each
2408 instruction must be executed only once each time through the loop.
2409 To verify this, we check that the insn is always executed, and that
2410 there are no backward branches after the insn that branch to before it.
2411 Also, the insn must have a mult_val of one (to make sure it really is
2414 result = const0_rtx;
2415 for (v = bl->biv; v; v = v->next_iv)
2417 if (v->always_computable && v->mult_val == const1_rtx
2418 && ! v->maybe_multiple)
2419 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2427 /* Determine the initial value of the iteration variable, and the amount
2428 that it is incremented each loop. Use the tables constructed by
2429 the strength reduction pass to calculate these values.
2431 Initial_value and/or increment are set to zero if their values could not
2435 iteration_info (loop, iteration_var, initial_value, increment)
2436 const struct loop *loop ATTRIBUTE_UNUSED;
2437 rtx iteration_var, *initial_value, *increment;
2439 struct iv_class *bl;
2441 /* Clear the result values, in case no answer can be found. */
2445 /* The iteration variable can be either a giv or a biv. Check to see
2446 which it is, and compute the variable's initial value, and increment
2447 value if possible. */
2449 /* If this is a new register, can't handle it since we don't have any
2450 reg_iv_type entry for it. */
2451 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
2453 if (loop_dump_stream)
2454 fprintf (loop_dump_stream,
2455 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2459 /* Reject iteration variables larger than the host wide int size, since they
2460 could result in a number of iterations greater than the range of our
2461 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2462 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2463 > HOST_BITS_PER_WIDE_INT))
2465 if (loop_dump_stream)
2466 fprintf (loop_dump_stream,
2467 "Loop unrolling: Iteration var rejected because mode too large.\n");
2470 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2472 if (loop_dump_stream)
2473 fprintf (loop_dump_stream,
2474 "Loop unrolling: Iteration var not an integer.\n");
2477 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2479 /* When reg_iv_type / reg_iv_info is resized for biv increments
2480 that are turned into givs, reg_biv_class is not resized.
2481 So check here that we don't make an out-of-bounds access. */
2482 if (REGNO (iteration_var) >= max_reg_before_loop)
2485 /* Grab initial value, only useful if it is a constant. */
2486 bl = reg_biv_class[REGNO (iteration_var)];
2487 *initial_value = bl->initial_value;
2489 *increment = biv_total_increment (bl);
2491 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2493 HOST_WIDE_INT offset = 0;
2494 struct induction *v = REG_IV_INFO (REGNO (iteration_var));
2496 if (REGNO (v->src_reg) >= max_reg_before_loop)
2499 bl = reg_biv_class[REGNO (v->src_reg)];
2501 /* Increment value is mult_val times the increment value of the biv. */
2503 *increment = biv_total_increment (bl);
2506 struct induction *biv_inc;
2509 = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, v->mode);
2510 /* The caller assumes that one full increment has occured at the
2511 first loop test. But that's not true when the biv is incremented
2512 after the giv is set (which is the usual case), e.g.:
2513 i = 6; do {;} while (i++ < 9) .
2514 Therefore, we bias the initial value by subtracting the amount of
2515 the increment that occurs between the giv set and the giv test. */
2516 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
2518 if (loop_insn_first_p (v->insn, biv_inc->insn))
2519 offset -= INTVAL (biv_inc->add_val);
2521 offset *= INTVAL (v->mult_val);
2523 if (loop_dump_stream)
2524 fprintf (loop_dump_stream,
2525 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2527 /* Initial value is mult_val times the biv's initial value plus
2528 add_val. Only useful if it is a constant. */
2530 = fold_rtx_mult_add (v->mult_val,
2531 plus_constant (bl->initial_value, offset),
2532 v->add_val, v->mode);
2536 if (loop_dump_stream)
2537 fprintf (loop_dump_stream,
2538 "Loop unrolling: Not basic or general induction var.\n");
2544 /* For each biv and giv, determine whether it can be safely split into
2545 a different variable for each unrolled copy of the loop body. If it
2546 is safe to split, then indicate that by saving some useful info
2547 in the splittable_regs array.
2549 If the loop is being completely unrolled, then splittable_regs will hold
2550 the current value of the induction variable while the loop is unrolled.
2551 It must be set to the initial value of the induction variable here.
2552 Otherwise, splittable_regs will hold the difference between the current
2553 value of the induction variable and the value the induction variable had
2554 at the top of the loop. It must be set to the value 0 here.
2556 Returns the total number of instructions that set registers that are
2559 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2560 constant values are unnecessary, since we can easily calculate increment
2561 values in this case even if nothing is constant. The increment value
2562 should not involve a multiply however. */
2564 /* ?? Even if the biv/giv increment values aren't constant, it may still
2565 be beneficial to split the variable if the loop is only unrolled a few
2566 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2569 find_splittable_regs (loop, unroll_type, end_insert_before, unroll_number)
2570 const struct loop *loop;
2571 enum unroll_types unroll_type;
2572 rtx end_insert_before;
2575 struct iv_class *bl;
2576 struct induction *v;
2578 rtx biv_final_value;
2581 rtx loop_start = loop->start;
2582 rtx loop_end = loop->end;
2584 for (bl = loop_iv_list; bl; bl = bl->next)
2586 /* Biv_total_increment must return a constant value,
2587 otherwise we can not calculate the split values. */
2589 increment = biv_total_increment (bl);
2590 if (! increment || GET_CODE (increment) != CONST_INT)
2593 /* The loop must be unrolled completely, or else have a known number
2594 of iterations and only one exit, or else the biv must be dead
2595 outside the loop, or else the final value must be known. Otherwise,
2596 it is unsafe to split the biv since it may not have the proper
2597 value on loop exit. */
2599 /* loop_number_exit_count is non-zero if the loop has an exit other than
2600 a fall through at the end. */
2603 biv_final_value = 0;
2604 if (unroll_type != UNROLL_COMPLETELY
2605 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2606 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2608 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2609 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2610 < INSN_LUID (bl->init_insn))
2611 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2612 && ! (biv_final_value = final_biv_value (loop, bl)))
2615 /* If any of the insns setting the BIV don't do so with a simple
2616 PLUS, we don't know how to split it. */
2617 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2618 if ((tem = single_set (v->insn)) == 0
2619 || GET_CODE (SET_DEST (tem)) != REG
2620 || REGNO (SET_DEST (tem)) != bl->regno
2621 || GET_CODE (SET_SRC (tem)) != PLUS)
2624 /* If final value is non-zero, then must emit an instruction which sets
2625 the value of the biv to the proper value. This is done after
2626 handling all of the givs, since some of them may need to use the
2627 biv's value in their initialization code. */
2629 /* This biv is splittable. If completely unrolling the loop, save
2630 the biv's initial value. Otherwise, save the constant zero. */
2632 if (biv_splittable == 1)
2634 if (unroll_type == UNROLL_COMPLETELY)
2636 /* If the initial value of the biv is itself (i.e. it is too
2637 complicated for strength_reduce to compute), or is a hard
2638 register, or it isn't invariant, then we must create a new
2639 pseudo reg to hold the initial value of the biv. */
2641 if (GET_CODE (bl->initial_value) == REG
2642 && (REGNO (bl->initial_value) == bl->regno
2643 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2644 || ! loop_invariant_p (loop, bl->initial_value)))
2646 rtx tem = gen_reg_rtx (bl->biv->mode);
2648 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2649 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2652 if (loop_dump_stream)
2653 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2654 bl->regno, REGNO (tem));
2656 splittable_regs[bl->regno] = tem;
2659 splittable_regs[bl->regno] = bl->initial_value;
2662 splittable_regs[bl->regno] = const0_rtx;
2664 /* Save the number of instructions that modify the biv, so that
2665 we can treat the last one specially. */
2667 splittable_regs_updates[bl->regno] = bl->biv_count;
2668 result += bl->biv_count;
2670 if (loop_dump_stream)
2671 fprintf (loop_dump_stream,
2672 "Biv %d safe to split.\n", bl->regno);
2675 /* Check every giv that depends on this biv to see whether it is
2676 splittable also. Even if the biv isn't splittable, givs which
2677 depend on it may be splittable if the biv is live outside the
2678 loop, and the givs aren't. */
2680 result += find_splittable_givs (loop, bl, unroll_type, increment,
2683 /* If final value is non-zero, then must emit an instruction which sets
2684 the value of the biv to the proper value. This is done after
2685 handling all of the givs, since some of them may need to use the
2686 biv's value in their initialization code. */
2687 if (biv_final_value)
2689 /* If the loop has multiple exits, emit the insns before the
2690 loop to ensure that it will always be executed no matter
2691 how the loop exits. Otherwise emit the insn after the loop,
2692 since this is slightly more efficient. */
2693 if (! loop->exit_count)
2694 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2699 /* Create a new register to hold the value of the biv, and then
2700 set the biv to its final value before the loop start. The biv
2701 is set to its final value before loop start to ensure that
2702 this insn will always be executed, no matter how the loop
2704 rtx tem = gen_reg_rtx (bl->biv->mode);
2705 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2707 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2709 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2713 if (loop_dump_stream)
2714 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2715 REGNO (bl->biv->src_reg), REGNO (tem));
2717 /* Set up the mapping from the original biv register to the new
2719 bl->biv->src_reg = tem;
2726 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2727 for the instruction that is using it. Do not make any changes to that
2731 verify_addresses (v, giv_inc, unroll_number)
2732 struct induction *v;
2737 rtx orig_addr = *v->location;
2738 rtx last_addr = plus_constant (v->dest_reg,
2739 INTVAL (giv_inc) * (unroll_number - 1));
2741 /* First check to see if either address would fail. Handle the fact
2742 that we have may have a match_dup. */
2743 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2744 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2747 /* Now put things back the way they were before. This should always
2749 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2755 /* For every giv based on the biv BL, check to determine whether it is
2756 splittable. This is a subroutine to find_splittable_regs ().
2758 Return the number of instructions that set splittable registers. */
2761 find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
2762 const struct loop *loop;
2763 struct iv_class *bl;
2764 enum unroll_types unroll_type;
2768 struct induction *v, *v2;
2773 /* Scan the list of givs, and set the same_insn field when there are
2774 multiple identical givs in the same insn. */
2775 for (v = bl->giv; v; v = v->next_iv)
2776 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2777 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2781 for (v = bl->giv; v; v = v->next_iv)
2785 /* Only split the giv if it has already been reduced, or if the loop is
2786 being completely unrolled. */
2787 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2790 /* The giv can be split if the insn that sets the giv is executed once
2791 and only once on every iteration of the loop. */
2792 /* An address giv can always be split. v->insn is just a use not a set,
2793 and hence it does not matter whether it is always executed. All that
2794 matters is that all the biv increments are always executed, and we
2795 won't reach here if they aren't. */
2796 if (v->giv_type != DEST_ADDR
2797 && (! v->always_computable
2798 || back_branch_in_range_p (loop, v->insn)))
2801 /* The giv increment value must be a constant. */
2802 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2804 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2807 /* The loop must be unrolled completely, or else have a known number of
2808 iterations and only one exit, or else the giv must be dead outside
2809 the loop, or else the final value of the giv must be known.
2810 Otherwise, it is not safe to split the giv since it may not have the
2811 proper value on loop exit. */
2813 /* The used outside loop test will fail for DEST_ADDR givs. They are
2814 never used outside the loop anyways, so it is always safe to split a
2818 if (unroll_type != UNROLL_COMPLETELY
2819 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2820 && v->giv_type != DEST_ADDR
2821 /* The next part is true if the pseudo is used outside the loop.
2822 We assume that this is true for any pseudo created after loop
2823 starts, because we don't have a reg_n_info entry for them. */
2824 && (REGNO (v->dest_reg) >= max_reg_before_loop
2825 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2826 /* Check for the case where the pseudo is set by a shift/add
2827 sequence, in which case the first insn setting the pseudo
2828 is the first insn of the shift/add sequence. */
2829 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2830 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2831 != INSN_UID (XEXP (tem, 0)))))
2832 /* Line above always fails if INSN was moved by loop opt. */
2833 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2834 >= INSN_LUID (loop->end)))
2835 /* Givs made from biv increments are missed by the above test, so
2836 test explicitly for them. */
2837 && (REGNO (v->dest_reg) < first_increment_giv
2838 || REGNO (v->dest_reg) > last_increment_giv)
2839 && ! (final_value = v->final_value))
2843 /* Currently, non-reduced/final-value givs are never split. */
2844 /* Should emit insns after the loop if possible, as the biv final value
2847 /* If the final value is non-zero, and the giv has not been reduced,
2848 then must emit an instruction to set the final value. */
2849 if (final_value && !v->new_reg)
2851 /* Create a new register to hold the value of the giv, and then set
2852 the giv to its final value before the loop start. The giv is set
2853 to its final value before loop start to ensure that this insn
2854 will always be executed, no matter how we exit. */
2855 tem = gen_reg_rtx (v->mode);
2856 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2857 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2860 if (loop_dump_stream)
2861 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2862 REGNO (v->dest_reg), REGNO (tem));
2868 /* This giv is splittable. If completely unrolling the loop, save the
2869 giv's initial value. Otherwise, save the constant zero for it. */
2871 if (unroll_type == UNROLL_COMPLETELY)
2873 /* It is not safe to use bl->initial_value here, because it may not
2874 be invariant. It is safe to use the initial value stored in
2875 the splittable_regs array if it is set. In rare cases, it won't
2876 be set, so then we do exactly the same thing as
2877 find_splittable_regs does to get a safe value. */
2878 rtx biv_initial_value;
2880 if (splittable_regs[bl->regno])
2881 biv_initial_value = splittable_regs[bl->regno];
2882 else if (GET_CODE (bl->initial_value) != REG
2883 || (REGNO (bl->initial_value) != bl->regno
2884 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2885 biv_initial_value = bl->initial_value;
2888 rtx tem = gen_reg_rtx (bl->biv->mode);
2890 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2891 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2893 biv_initial_value = tem;
2895 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2896 v->add_val, v->mode);
2903 /* If a giv was combined with another giv, then we can only split
2904 this giv if the giv it was combined with was reduced. This
2905 is because the value of v->new_reg is meaningless in this
2907 if (v->same && ! v->same->new_reg)
2909 if (loop_dump_stream)
2910 fprintf (loop_dump_stream,
2911 "giv combined with unreduced giv not split.\n");
2914 /* If the giv is an address destination, it could be something other
2915 than a simple register, these have to be treated differently. */
2916 else if (v->giv_type == DEST_REG)
2918 /* If value is not a constant, register, or register plus
2919 constant, then compute its value into a register before
2920 loop start. This prevents invalid rtx sharing, and should
2921 generate better code. We can use bl->initial_value here
2922 instead of splittable_regs[bl->regno] because this code
2923 is going before the loop start. */
2924 if (unroll_type == UNROLL_COMPLETELY
2925 && GET_CODE (value) != CONST_INT
2926 && GET_CODE (value) != REG
2927 && (GET_CODE (value) != PLUS
2928 || GET_CODE (XEXP (value, 0)) != REG
2929 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2931 rtx tem = gen_reg_rtx (v->mode);
2932 record_base_value (REGNO (tem), v->add_val, 0);
2933 emit_iv_add_mult (bl->initial_value, v->mult_val,
2934 v->add_val, tem, loop->start);
2938 splittable_regs[REGNO (v->new_reg)] = value;
2939 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2943 /* Splitting address givs is useful since it will often allow us
2944 to eliminate some increment insns for the base giv as
2947 /* If the addr giv is combined with a dest_reg giv, then all
2948 references to that dest reg will be remapped, which is NOT
2949 what we want for split addr regs. We always create a new
2950 register for the split addr giv, just to be safe. */
2952 /* If we have multiple identical address givs within a
2953 single instruction, then use a single pseudo reg for
2954 both. This is necessary in case one is a match_dup
2957 v->const_adjust = 0;
2961 v->dest_reg = v->same_insn->dest_reg;
2962 if (loop_dump_stream)
2963 fprintf (loop_dump_stream,
2964 "Sharing address givs in insn %d\n",
2965 INSN_UID (v->insn));
2967 /* If multiple address GIVs have been combined with the
2968 same dest_reg GIV, do not create a new register for
2970 else if (unroll_type != UNROLL_COMPLETELY
2971 && v->giv_type == DEST_ADDR
2972 && v->same && v->same->giv_type == DEST_ADDR
2973 && v->same->unrolled
2974 /* combine_givs_p may return true for some cases
2975 where the add and mult values are not equal.
2976 To share a register here, the values must be
2978 && rtx_equal_p (v->same->mult_val, v->mult_val)
2979 && rtx_equal_p (v->same->add_val, v->add_val)
2980 /* If the memory references have different modes,
2981 then the address may not be valid and we must
2982 not share registers. */
2983 && verify_addresses (v, giv_inc, unroll_number))
2985 v->dest_reg = v->same->dest_reg;
2988 else if (unroll_type != UNROLL_COMPLETELY)
2990 /* If not completely unrolling the loop, then create a new
2991 register to hold the split value of the DEST_ADDR giv.
2992 Emit insn to initialize its value before loop start. */
2994 rtx tem = gen_reg_rtx (v->mode);
2995 struct induction *same = v->same;
2996 rtx new_reg = v->new_reg;
2997 record_base_value (REGNO (tem), v->add_val, 0);
2999 if (same && same->derived_from)
3001 /* calculate_giv_inc doesn't work for derived givs.
3002 copy_loop_body works around the problem for the
3003 DEST_REG givs themselves, but it can't handle
3004 DEST_ADDR givs that have been combined with
3005 a derived DEST_REG giv.
3006 So Handle V as if the giv from which V->SAME has
3007 been derived has been combined with V.
3008 recombine_givs only derives givs from givs that
3009 are reduced the ordinary, so we need not worry
3010 about same->derived_from being in turn derived. */
3012 same = same->derived_from;
3013 new_reg = express_from (same, v);
3014 new_reg = replace_rtx (new_reg, same->dest_reg,
3018 /* If the address giv has a constant in its new_reg value,
3019 then this constant can be pulled out and put in value,
3020 instead of being part of the initialization code. */
3022 if (GET_CODE (new_reg) == PLUS
3023 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
3026 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
3028 /* Only succeed if this will give valid addresses.
3029 Try to validate both the first and the last
3030 address resulting from loop unrolling, if
3031 one fails, then can't do const elim here. */
3032 if (verify_addresses (v, giv_inc, unroll_number))
3034 /* Save the negative of the eliminated const, so
3035 that we can calculate the dest_reg's increment
3037 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
3039 new_reg = XEXP (new_reg, 0);
3040 if (loop_dump_stream)
3041 fprintf (loop_dump_stream,
3042 "Eliminating constant from giv %d\n",
3051 /* If the address hasn't been checked for validity yet, do so
3052 now, and fail completely if either the first or the last
3053 unrolled copy of the address is not a valid address
3054 for the instruction that uses it. */
3055 if (v->dest_reg == tem
3056 && ! verify_addresses (v, giv_inc, unroll_number))
3058 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3059 if (v2->same_insn == v)
3062 if (loop_dump_stream)
3063 fprintf (loop_dump_stream,
3064 "Invalid address for giv at insn %d\n",
3065 INSN_UID (v->insn));
3069 v->new_reg = new_reg;
3072 /* We set this after the address check, to guarantee that
3073 the register will be initialized. */
3076 /* To initialize the new register, just move the value of
3077 new_reg into it. This is not guaranteed to give a valid
3078 instruction on machines with complex addressing modes.
3079 If we can't recognize it, then delete it and emit insns
3080 to calculate the value from scratch. */
3081 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
3082 copy_rtx (v->new_reg)),
3084 if (recog_memoized (PREV_INSN (loop->start)) < 0)
3088 /* We can't use bl->initial_value to compute the initial
3089 value, because the loop may have been preconditioned.
3090 We must calculate it from NEW_REG. Try using
3091 force_operand instead of emit_iv_add_mult. */
3092 delete_insn (PREV_INSN (loop->start));
3095 ret = force_operand (v->new_reg, tem);
3097 emit_move_insn (tem, ret);
3098 sequence = gen_sequence ();
3100 emit_insn_before (sequence, loop->start);
3102 if (loop_dump_stream)
3103 fprintf (loop_dump_stream,
3104 "Invalid init insn, rewritten.\n");
3109 v->dest_reg = value;
3111 /* Check the resulting address for validity, and fail
3112 if the resulting address would be invalid. */
3113 if (! verify_addresses (v, giv_inc, unroll_number))
3115 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3116 if (v2->same_insn == v)
3119 if (loop_dump_stream)
3120 fprintf (loop_dump_stream,
3121 "Invalid address for giv at insn %d\n",
3122 INSN_UID (v->insn));
3125 if (v->same && v->same->derived_from)
3127 /* Handle V as if the giv from which V->SAME has
3128 been derived has been combined with V. */
3130 v->same = v->same->derived_from;
3131 v->new_reg = express_from (v->same, v);
3132 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3138 /* Store the value of dest_reg into the insn. This sharing
3139 will not be a problem as this insn will always be copied
3142 *v->location = v->dest_reg;
3144 /* If this address giv is combined with a dest reg giv, then
3145 save the base giv's induction pointer so that we will be
3146 able to handle this address giv properly. The base giv
3147 itself does not have to be splittable. */
3149 if (v->same && v->same->giv_type == DEST_REG)
3150 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3152 if (GET_CODE (v->new_reg) == REG)
3154 /* This giv maybe hasn't been combined with any others.
3155 Make sure that it's giv is marked as splittable here. */
3157 splittable_regs[REGNO (v->new_reg)] = value;
3158 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3160 /* Make it appear to depend upon itself, so that the
3161 giv will be properly split in the main loop above. */
3165 addr_combined_regs[REGNO (v->new_reg)] = v;
3169 if (loop_dump_stream)
3170 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3176 /* Currently, unreduced giv's can't be split. This is not too much
3177 of a problem since unreduced giv's are not live across loop
3178 iterations anyways. When unrolling a loop completely though,
3179 it makes sense to reduce&split givs when possible, as this will
3180 result in simpler instructions, and will not require that a reg
3181 be live across loop iterations. */
3183 splittable_regs[REGNO (v->dest_reg)] = value;
3184 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3185 REGNO (v->dest_reg), INSN_UID (v->insn));
3191 /* Unreduced givs are only updated once by definition. Reduced givs
3192 are updated as many times as their biv is. Mark it so if this is
3193 a splittable register. Don't need to do anything for address givs
3194 where this may not be a register. */
3196 if (GET_CODE (v->new_reg) == REG)
3200 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3202 if (count > 1 && v->derived_from)
3203 /* In this case, there is one set where the giv insn was and one
3204 set each after each biv increment. (Most are likely dead.) */
3207 splittable_regs_updates[REGNO (v->new_reg)] = count;
3212 if (loop_dump_stream)
3216 if (GET_CODE (v->dest_reg) == CONST_INT)
3218 else if (GET_CODE (v->dest_reg) != REG)
3219 regnum = REGNO (XEXP (v->dest_reg, 0));
3221 regnum = REGNO (v->dest_reg);
3222 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3223 regnum, INSN_UID (v->insn));
3230 /* Try to prove that the register is dead after the loop exits. Trace every
3231 loop exit looking for an insn that will always be executed, which sets
3232 the register to some value, and appears before the first use of the register
3233 is found. If successful, then return 1, otherwise return 0. */
3235 /* ?? Could be made more intelligent in the handling of jumps, so that
3236 it can search past if statements and other similar structures. */
3239 reg_dead_after_loop (loop, reg)
3240 const struct loop *loop;
3246 int label_count = 0;
3248 /* In addition to checking all exits of this loop, we must also check
3249 all exits of inner nested loops that would exit this loop. We don't
3250 have any way to identify those, so we just give up if there are any
3251 such inner loop exits. */
3253 for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
3256 if (label_count != loop->exit_count)
3259 /* HACK: Must also search the loop fall through exit, create a label_ref
3260 here which points to the loop->end, and append the loop_number_exit_labels
3262 label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
3263 LABEL_NEXTREF (label) = loop->exit_labels;
3265 for ( ; label; label = LABEL_NEXTREF (label))
3267 /* Succeed if find an insn which sets the biv or if reach end of
3268 function. Fail if find an insn that uses the biv, or if come to
3269 a conditional jump. */
3271 insn = NEXT_INSN (XEXP (label, 0));
3274 code = GET_CODE (insn);
3275 if (GET_RTX_CLASS (code) == 'i')
3279 if (reg_referenced_p (reg, PATTERN (insn)))
3282 set = single_set (insn);
3283 if (set && rtx_equal_p (SET_DEST (set), reg))
3287 if (code == JUMP_INSN)
3289 if (GET_CODE (PATTERN (insn)) == RETURN)
3291 else if (! simplejump_p (insn)
3292 /* Prevent infinite loop following infinite loops. */
3293 || jump_count++ > 20)
3296 insn = JUMP_LABEL (insn);
3299 insn = NEXT_INSN (insn);
3303 /* Success, the register is dead on all loop exits. */
3307 /* Try to calculate the final value of the biv, the value it will have at
3308 the end of the loop. If we can do it, return that value. */
3311 final_biv_value (loop, bl)
3312 const struct loop *loop;
3313 struct iv_class *bl;
3315 rtx loop_end = loop->end;
3316 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3319 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3321 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3324 /* The final value for reversed bivs must be calculated differently than
3325 for ordinary bivs. In this case, there is already an insn after the
3326 loop which sets this biv's final value (if necessary), and there are
3327 no other loop exits, so we can return any value. */
3330 if (loop_dump_stream)
3331 fprintf (loop_dump_stream,
3332 "Final biv value for %d, reversed biv.\n", bl->regno);
3337 /* Try to calculate the final value as initial value + (number of iterations
3338 * increment). For this to work, increment must be invariant, the only
3339 exit from the loop must be the fall through at the bottom (otherwise
3340 it may not have its final value when the loop exits), and the initial
3341 value of the biv must be invariant. */
3343 if (n_iterations != 0
3344 && ! loop->exit_count
3345 && loop_invariant_p (loop, bl->initial_value))
3347 increment = biv_total_increment (bl);
3349 if (increment && loop_invariant_p (loop, increment))
3351 /* Can calculate the loop exit value, emit insns after loop
3352 end to calculate this value into a temporary register in
3353 case it is needed later. */
3355 tem = gen_reg_rtx (bl->biv->mode);
3356 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3357 /* Make sure loop_end is not the last insn. */
3358 if (NEXT_INSN (loop_end) == 0)
3359 emit_note_after (NOTE_INSN_DELETED, loop_end);
3360 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3361 bl->initial_value, tem, NEXT_INSN (loop_end));
3363 if (loop_dump_stream)
3364 fprintf (loop_dump_stream,
3365 "Final biv value for %d, calculated.\n", bl->regno);
3371 /* Check to see if the biv is dead at all loop exits. */
3372 if (reg_dead_after_loop (loop, bl->biv->src_reg))
3374 if (loop_dump_stream)
3375 fprintf (loop_dump_stream,
3376 "Final biv value for %d, biv dead after loop exit.\n",
3385 /* Try to calculate the final value of the giv, the value it will have at
3386 the end of the loop. If we can do it, return that value. */
3389 final_giv_value (loop, v)
3390 const struct loop *loop;
3391 struct induction *v;
3393 struct iv_class *bl;
3396 rtx insert_before, seq;
3397 rtx loop_end = loop->end;
3398 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3400 bl = reg_biv_class[REGNO (v->src_reg)];
3402 /* The final value for givs which depend on reversed bivs must be calculated
3403 differently than for ordinary givs. In this case, there is already an
3404 insn after the loop which sets this giv's final value (if necessary),
3405 and there are no other loop exits, so we can return any value. */
3408 if (loop_dump_stream)
3409 fprintf (loop_dump_stream,
3410 "Final giv value for %d, depends on reversed biv\n",
3411 REGNO (v->dest_reg));
3415 /* Try to calculate the final value as a function of the biv it depends
3416 upon. The only exit from the loop must be the fall through at the bottom
3417 (otherwise it may not have its final value when the loop exits). */
3419 /* ??? Can calculate the final giv value by subtracting off the
3420 extra biv increments times the giv's mult_val. The loop must have
3421 only one exit for this to work, but the loop iterations does not need
3424 if (n_iterations != 0
3425 && ! loop->exit_count)
3427 /* ?? It is tempting to use the biv's value here since these insns will
3428 be put after the loop, and hence the biv will have its final value
3429 then. However, this fails if the biv is subsequently eliminated.
3430 Perhaps determine whether biv's are eliminable before trying to
3431 determine whether giv's are replaceable so that we can use the
3432 biv value here if it is not eliminable. */
3434 /* We are emitting code after the end of the loop, so we must make
3435 sure that bl->initial_value is still valid then. It will still
3436 be valid if it is invariant. */
3438 increment = biv_total_increment (bl);
3440 if (increment && loop_invariant_p (loop, increment)
3441 && loop_invariant_p (loop, bl->initial_value))
3443 /* Can calculate the loop exit value of its biv as
3444 (n_iterations * increment) + initial_value */
3446 /* The loop exit value of the giv is then
3447 (final_biv_value - extra increments) * mult_val + add_val.
3448 The extra increments are any increments to the biv which
3449 occur in the loop after the giv's value is calculated.
3450 We must search from the insn that sets the giv to the end
3451 of the loop to calculate this value. */
3453 insert_before = NEXT_INSN (loop_end);
3455 /* Put the final biv value in tem. */
3456 tem = gen_reg_rtx (bl->biv->mode);
3457 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3458 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3459 bl->initial_value, tem, insert_before);
3461 /* Subtract off extra increments as we find them. */
3462 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3463 insn = NEXT_INSN (insn))
3465 struct induction *biv;
3467 for (biv = bl->biv; biv; biv = biv->next_iv)
3468 if (biv->insn == insn)
3471 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3472 biv->add_val, NULL_RTX, 0,
3474 seq = gen_sequence ();
3476 emit_insn_before (seq, insert_before);
3480 /* Now calculate the giv's final value. */
3481 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3484 if (loop_dump_stream)
3485 fprintf (loop_dump_stream,
3486 "Final giv value for %d, calc from biv's value.\n",
3487 REGNO (v->dest_reg));
3493 /* Replaceable giv's should never reach here. */
3497 /* Check to see if the biv is dead at all loop exits. */
3498 if (reg_dead_after_loop (loop, v->dest_reg))
3500 if (loop_dump_stream)
3501 fprintf (loop_dump_stream,
3502 "Final giv value for %d, giv dead after loop exit.\n",
3503 REGNO (v->dest_reg));
3512 /* Look back before LOOP->START for then insn that sets REG and return
3513 the equivalent constant if there is a REG_EQUAL note otherwise just
3514 the SET_SRC of REG. */
3517 loop_find_equiv_value (loop, reg)
3518 const struct loop *loop;
3521 rtx loop_start = loop->start;
3526 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3528 if (GET_CODE (insn) == CODE_LABEL)
3531 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3532 && reg_set_p (reg, insn))
3534 /* We found the last insn before the loop that sets the register.
3535 If it sets the entire register, and has a REG_EQUAL note,
3536 then use the value of the REG_EQUAL note. */
3537 if ((set = single_set (insn))
3538 && (SET_DEST (set) == reg))
3540 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3542 /* Only use the REG_EQUAL note if it is a constant.
3543 Other things, divide in particular, will cause
3544 problems later if we use them. */
3545 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3546 && CONSTANT_P (XEXP (note, 0)))
3547 ret = XEXP (note, 0);
3549 ret = SET_SRC (set);
3557 /* Return a simplified rtx for the expression OP - REG.
3559 REG must appear in OP, and OP must be a register or the sum of a register
3562 Thus, the return value must be const0_rtx or the second term.
3564 The caller is responsible for verifying that REG appears in OP and OP has
3568 subtract_reg_term (op, reg)
3573 if (GET_CODE (op) == PLUS)
3575 if (XEXP (op, 0) == reg)
3576 return XEXP (op, 1);
3577 else if (XEXP (op, 1) == reg)
3578 return XEXP (op, 0);
3580 /* OP does not contain REG as a term. */
3585 /* Find and return register term common to both expressions OP0 and
3586 OP1 or NULL_RTX if no such term exists. Each expression must be a
3587 REG or a PLUS of a REG. */
3590 find_common_reg_term (op0, op1)
3593 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3594 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3601 if (GET_CODE (op0) == PLUS)
3602 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3604 op01 = const0_rtx, op00 = op0;
3606 if (GET_CODE (op1) == PLUS)
3607 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3609 op11 = const0_rtx, op10 = op1;
3611 /* Find and return common register term if present. */
3612 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3614 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3618 /* No common register term found. */
3622 /* Calculate the number of loop iterations. Returns the exact number of loop
3623 iterations if it can be calculated, otherwise returns zero. */
3625 unsigned HOST_WIDE_INT
3626 loop_iterations (loop)
3629 rtx comparison, comparison_value;
3630 rtx iteration_var, initial_value, increment, final_value;
3631 enum rtx_code comparison_code;
3632 HOST_WIDE_INT abs_inc;
3633 unsigned HOST_WIDE_INT abs_diff;
3636 int unsigned_p, compare_dir, final_larger;
3639 struct loop_info *loop_info = LOOP_INFO (loop);
3641 loop_info->n_iterations = 0;
3642 loop_info->initial_value = 0;
3643 loop_info->initial_equiv_value = 0;
3644 loop_info->comparison_value = 0;
3645 loop_info->final_value = 0;
3646 loop_info->final_equiv_value = 0;
3647 loop_info->increment = 0;
3648 loop_info->iteration_var = 0;
3649 loop_info->unroll_number = 1;
3651 /* We used to use prev_nonnote_insn here, but that fails because it might
3652 accidentally get the branch for a contained loop if the branch for this
3653 loop was deleted. We can only trust branches immediately before the
3655 last_loop_insn = PREV_INSN (loop->end);
3657 /* ??? We should probably try harder to find the jump insn
3658 at the end of the loop. The following code assumes that
3659 the last loop insn is a jump to the top of the loop. */
3660 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3662 if (loop_dump_stream)
3663 fprintf (loop_dump_stream,
3664 "Loop iterations: No final conditional branch found.\n");
3668 /* If there is a more than a single jump to the top of the loop
3669 we cannot (easily) determine the iteration count. */
3670 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3672 if (loop_dump_stream)
3673 fprintf (loop_dump_stream,
3674 "Loop iterations: Loop has multiple back edges.\n");
3678 /* Find the iteration variable. If the last insn is a conditional
3679 branch, and the insn before tests a register value, make that the
3680 iteration variable. */
3682 comparison = get_condition_for_loop (loop, last_loop_insn);
3683 if (comparison == 0)
3685 if (loop_dump_stream)
3686 fprintf (loop_dump_stream,
3687 "Loop iterations: No final comparison found.\n");
3691 /* ??? Get_condition may switch position of induction variable and
3692 invariant register when it canonicalizes the comparison. */
3694 comparison_code = GET_CODE (comparison);
3695 iteration_var = XEXP (comparison, 0);
3696 comparison_value = XEXP (comparison, 1);
3698 if (GET_CODE (iteration_var) != REG)
3700 if (loop_dump_stream)
3701 fprintf (loop_dump_stream,
3702 "Loop iterations: Comparison not against register.\n");
3706 /* The only new registers that are created before loop iterations
3707 are givs made from biv increments or registers created by
3708 load_mems. In the latter case, it is possible that try_copy_prop
3709 will propagate a new pseudo into the old iteration register but
3710 this will be marked by having the REG_USERVAR_P bit set. */
3712 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements
3713 && ! REG_USERVAR_P (iteration_var))
3716 iteration_info (loop, iteration_var, &initial_value, &increment);
3718 if (initial_value == 0)
3719 /* iteration_info already printed a message. */
3724 switch (comparison_code)
3739 /* Cannot determine loop iterations with this case. */
3758 /* If the comparison value is an invariant register, then try to find
3759 its value from the insns before the start of the loop. */
3761 final_value = comparison_value;
3762 if (GET_CODE (comparison_value) == REG
3763 && loop_invariant_p (loop, comparison_value))
3765 final_value = loop_find_equiv_value (loop, comparison_value);
3767 /* If we don't get an invariant final value, we are better
3768 off with the original register. */
3769 if (! loop_invariant_p (loop, final_value))
3770 final_value = comparison_value;
3773 /* Calculate the approximate final value of the induction variable
3774 (on the last successful iteration). The exact final value
3775 depends on the branch operator, and increment sign. It will be
3776 wrong if the iteration variable is not incremented by one each
3777 time through the loop and (comparison_value + off_by_one -
3778 initial_value) % increment != 0.
3779 ??? Note that the final_value may overflow and thus final_larger
3780 will be bogus. A potentially infinite loop will be classified
3781 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3783 final_value = plus_constant (final_value, off_by_one);
3785 /* Save the calculated values describing this loop's bounds, in case
3786 precondition_loop_p will need them later. These values can not be
3787 recalculated inside precondition_loop_p because strength reduction
3788 optimizations may obscure the loop's structure.
3790 These values are only required by precondition_loop_p and insert_bct
3791 whenever the number of iterations cannot be computed at compile time.
3792 Only the difference between final_value and initial_value is
3793 important. Note that final_value is only approximate. */
3794 loop_info->initial_value = initial_value;
3795 loop_info->comparison_value = comparison_value;
3796 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3797 loop_info->increment = increment;
3798 loop_info->iteration_var = iteration_var;
3799 loop_info->comparison_code = comparison_code;
3801 /* Try to determine the iteration count for loops such
3802 as (for i = init; i < init + const; i++). When running the
3803 loop optimization twice, the first pass often converts simple
3804 loops into this form. */
3806 if (REG_P (initial_value))
3812 reg1 = initial_value;
3813 if (GET_CODE (final_value) == PLUS)
3814 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3816 reg2 = final_value, const2 = const0_rtx;
3818 /* Check for initial_value = reg1, final_value = reg2 + const2,
3819 where reg1 != reg2. */
3820 if (REG_P (reg2) && reg2 != reg1)
3824 /* Find what reg1 is equivalent to. Hopefully it will
3825 either be reg2 or reg2 plus a constant. */
3826 temp = loop_find_equiv_value (loop, reg1);
3828 if (find_common_reg_term (temp, reg2))
3829 initial_value = temp;
3832 /* Find what reg2 is equivalent to. Hopefully it will
3833 either be reg1 or reg1 plus a constant. Let's ignore
3834 the latter case for now since it is not so common. */
3835 temp = loop_find_equiv_value (loop, reg2);
3837 if (temp == loop_info->iteration_var)
3838 temp = initial_value;
3840 final_value = (const2 == const0_rtx)
3841 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3844 else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
3848 /* When running the loop optimizer twice, check_dbra_loop
3849 further obfuscates reversible loops of the form:
3850 for (i = init; i < init + const; i++). We often end up with
3851 final_value = 0, initial_value = temp, temp = temp2 - init,
3852 where temp2 = init + const. If the loop has a vtop we
3853 can replace initial_value with const. */
3855 temp = loop_find_equiv_value (loop, reg1);
3857 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3859 rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
3861 if (GET_CODE (temp2) == PLUS
3862 && XEXP (temp2, 0) == XEXP (temp, 1))
3863 initial_value = XEXP (temp2, 1);
3868 /* If have initial_value = reg + const1 and final_value = reg +
3869 const2, then replace initial_value with const1 and final_value
3870 with const2. This should be safe since we are protected by the
3871 initial comparison before entering the loop if we have a vtop.
3872 For example, a + b < a + c is not equivalent to b < c for all a
3873 when using modulo arithmetic.
3875 ??? Without a vtop we could still perform the optimization if we check
3876 the initial and final values carefully. */
3878 && (reg_term = find_common_reg_term (initial_value, final_value)))
3880 initial_value = subtract_reg_term (initial_value, reg_term);
3881 final_value = subtract_reg_term (final_value, reg_term);
3884 loop_info->initial_equiv_value = initial_value;
3885 loop_info->final_equiv_value = final_value;
3887 /* For EQ comparison loops, we don't have a valid final value.
3888 Check this now so that we won't leave an invalid value if we
3889 return early for any other reason. */
3890 if (comparison_code == EQ)
3891 loop_info->final_equiv_value = loop_info->final_value = 0;
3895 if (loop_dump_stream)
3896 fprintf (loop_dump_stream,
3897 "Loop iterations: Increment value can't be calculated.\n");
3901 if (GET_CODE (increment) != CONST_INT)
3903 /* If we have a REG, check to see if REG holds a constant value. */
3904 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3905 clear if it is worthwhile to try to handle such RTL. */
3906 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3907 increment = loop_find_equiv_value (loop, increment);
3909 if (GET_CODE (increment) != CONST_INT)
3911 if (loop_dump_stream)
3913 fprintf (loop_dump_stream,
3914 "Loop iterations: Increment value not constant ");
3915 print_rtl (loop_dump_stream, increment);
3916 fprintf (loop_dump_stream, ".\n");
3920 loop_info->increment = increment;
3923 if (GET_CODE (initial_value) != CONST_INT)
3925 if (loop_dump_stream)
3927 fprintf (loop_dump_stream,
3928 "Loop iterations: Initial value not constant ");
3929 print_rtl (loop_dump_stream, initial_value);
3930 fprintf (loop_dump_stream, ".\n");
3934 else if (comparison_code == EQ)
3936 if (loop_dump_stream)
3937 fprintf (loop_dump_stream,
3938 "Loop iterations: EQ comparison loop.\n");
3941 else if (GET_CODE (final_value) != CONST_INT)
3943 if (loop_dump_stream)
3945 fprintf (loop_dump_stream,
3946 "Loop iterations: Final value not constant ");
3947 print_rtl (loop_dump_stream, final_value);
3948 fprintf (loop_dump_stream, ".\n");
3953 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3956 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3957 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3958 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3959 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3961 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3962 - (INTVAL (final_value) < INTVAL (initial_value));
3964 if (INTVAL (increment) > 0)
3966 else if (INTVAL (increment) == 0)
3971 /* There are 27 different cases: compare_dir = -1, 0, 1;
3972 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3973 There are 4 normal cases, 4 reverse cases (where the iteration variable
3974 will overflow before the loop exits), 4 infinite loop cases, and 15
3975 immediate exit (0 or 1 iteration depending on loop type) cases.
3976 Only try to optimize the normal cases. */
3978 /* (compare_dir/final_larger/increment_dir)
3979 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3980 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3981 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3982 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3984 /* ?? If the meaning of reverse loops (where the iteration variable
3985 will overflow before the loop exits) is undefined, then could
3986 eliminate all of these special checks, and just always assume
3987 the loops are normal/immediate/infinite. Note that this means
3988 the sign of increment_dir does not have to be known. Also,
3989 since it does not really hurt if immediate exit loops or infinite loops
3990 are optimized, then that case could be ignored also, and hence all
3991 loops can be optimized.
3993 According to ANSI Spec, the reverse loop case result is undefined,
3994 because the action on overflow is undefined.
3996 See also the special test for NE loops below. */
3998 if (final_larger == increment_dir && final_larger != 0
3999 && (final_larger == compare_dir || compare_dir == 0))
4004 if (loop_dump_stream)
4005 fprintf (loop_dump_stream,
4006 "Loop iterations: Not normal loop.\n");
4010 /* Calculate the number of iterations, final_value is only an approximation,
4011 so correct for that. Note that abs_diff and n_iterations are
4012 unsigned, because they can be as large as 2^n - 1. */
4014 abs_inc = INTVAL (increment);
4016 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
4017 else if (abs_inc < 0)
4019 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
4025 /* For NE tests, make sure that the iteration variable won't miss
4026 the final value. If abs_diff mod abs_incr is not zero, then the
4027 iteration variable will overflow before the loop exits, and we
4028 can not calculate the number of iterations. */
4029 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4032 /* Note that the number of iterations could be calculated using
4033 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4034 handle potential overflow of the summation. */
4035 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4036 return loop_info->n_iterations;
4040 /* Replace uses of split bivs with their split pseudo register. This is
4041 for original instructions which remain after loop unrolling without
4045 remap_split_bivs (x)
4048 register enum rtx_code code;
4050 register const char *fmt;
4055 code = GET_CODE (x);
4070 /* If non-reduced/final-value givs were split, then this would also
4071 have to remap those givs also. */
4073 if (REGNO (x) < max_reg_before_loop
4074 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
4075 return reg_biv_class[REGNO (x)]->biv->src_reg;
4082 fmt = GET_RTX_FORMAT (code);
4083 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4086 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
4087 else if (fmt[i] == 'E')
4090 for (j = 0; j < XVECLEN (x, i); j++)
4091 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
4097 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4098 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4099 return 0. COPY_START is where we can start looking for the insns
4100 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4103 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4104 must dominate LAST_UID.
4106 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4107 may not dominate LAST_UID.
4109 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4110 must dominate LAST_UID. */
4113 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4120 int passed_jump = 0;
4121 rtx p = NEXT_INSN (copy_start);
4123 while (INSN_UID (p) != first_uid)
4125 if (GET_CODE (p) == JUMP_INSN)
4127 /* Could not find FIRST_UID. */
4133 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4134 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
4135 || ! dead_or_set_regno_p (p, regno))
4138 /* FIRST_UID is always executed. */
4139 if (passed_jump == 0)
4142 while (INSN_UID (p) != last_uid)
4144 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4145 can not be sure that FIRST_UID dominates LAST_UID. */
4146 if (GET_CODE (p) == CODE_LABEL)
4148 /* Could not find LAST_UID, but we reached the end of the loop, so
4150 else if (p == copy_end)
4155 /* FIRST_UID is always executed if LAST_UID is executed. */