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"
163 #include "hard-reg-set.h"
164 #include "basic-block.h"
166 /* This controls which loops are unrolled, and by how much we unroll
169 #ifndef MAX_UNROLLED_INSNS
170 #define MAX_UNROLLED_INSNS 100
173 /* Indexed by register number, if non-zero, then it contains a pointer
174 to a struct induction for a DEST_REG giv which has been combined with
175 one of more address givs. This is needed because whenever such a DEST_REG
176 giv is modified, we must modify the value of all split address givs
177 that were combined with this DEST_REG giv. */
179 static struct induction **addr_combined_regs;
181 /* Indexed by register number, if this is a splittable induction variable,
182 then this will hold the current value of the register, which depends on the
185 static rtx *splittable_regs;
187 /* Indexed by register number, if this is a splittable induction variable,
188 this indicates if it was made from a derived giv. */
189 static char *derived_regs;
191 /* Indexed by register number, if this is a splittable induction variable,
192 then this will hold the number of instructions in the loop that modify
193 the induction variable. Used to ensure that only the last insn modifying
194 a split iv will update the original iv of the dest. */
196 static int *splittable_regs_updates;
198 /* Forward declarations. */
200 static void init_reg_map PARAMS ((struct inline_remap *, int));
201 static rtx calculate_giv_inc PARAMS ((rtx, rtx, unsigned int));
202 static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
203 static void final_reg_note_copy PARAMS ((rtx, struct inline_remap *));
204 static void copy_loop_body PARAMS ((rtx, rtx, struct inline_remap *, rtx, int,
205 enum unroll_types, rtx, rtx, rtx, rtx));
206 static void iteration_info PARAMS ((const struct loop *, rtx, rtx *, rtx *));
207 static int find_splittable_regs PARAMS ((const struct loop *,
208 enum unroll_types, rtx, int));
209 static int find_splittable_givs PARAMS ((const struct loop *,
210 struct iv_class *, enum unroll_types,
212 static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
213 static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
214 static int verify_addresses PARAMS ((struct induction *, rtx, int));
215 static rtx remap_split_bivs PARAMS ((rtx));
216 static rtx find_common_reg_term PARAMS ((rtx, rtx));
217 static rtx subtract_reg_term PARAMS ((rtx, rtx));
218 static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
219 static rtx ujump_to_loop_cont PARAMS ((rtx, rtx));
221 /* Try to unroll one loop and split induction variables in the loop.
223 The loop is described by the arguments LOOP and INSN_COUNT.
224 END_INSERT_BEFORE indicates where insns should be added which need
225 to be executed when the loop falls through. STRENGTH_REDUCTION_P
226 indicates whether information generated in the strength reduction
229 This function is intended to be called from within `strength_reduce'
233 unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
236 rtx end_insert_before;
237 int strength_reduce_p;
241 unsigned HOST_WIDE_INT temp;
242 int unroll_number = 1;
243 rtx copy_start, copy_end;
244 rtx insn, sequence, pattern, tem;
245 int max_labelno, max_insnno;
247 struct inline_remap *map;
248 char *local_label = NULL;
250 unsigned int max_local_regnum;
251 unsigned int maxregnum;
255 int splitting_not_safe = 0;
256 enum unroll_types unroll_type = UNROLL_NAIVE;
257 int loop_preconditioned = 0;
259 /* This points to the last real insn in the loop, which should be either
260 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
263 rtx loop_start = loop->start;
264 rtx loop_end = loop->end;
265 struct loop_info *loop_info = LOOP_INFO (loop);
267 /* Don't bother unrolling huge loops. Since the minimum factor is
268 two, loops greater than one half of MAX_UNROLLED_INSNS will never
270 if (insn_count > MAX_UNROLLED_INSNS / 2)
272 if (loop_dump_stream)
273 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
277 /* When emitting debugger info, we can't unroll loops with unequal numbers
278 of block_beg and block_end notes, because that would unbalance the block
279 structure of the function. This can happen as a result of the
280 "if (foo) bar; else break;" optimization in jump.c. */
281 /* ??? Gcc has a general policy that -g is never supposed to change the code
282 that the compiler emits, so we must disable this optimization always,
283 even if debug info is not being output. This is rare, so this should
284 not be a significant performance problem. */
286 if (1 /* write_symbols != NO_DEBUG */)
288 int block_begins = 0;
291 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
293 if (GET_CODE (insn) == NOTE)
295 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
297 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
299 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
300 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
302 /* Note, would be nice to add code to unroll EH
303 regions, but until that time, we punt (don't
304 unroll). For the proper way of doing it, see
305 expand_inline_function. */
307 if (loop_dump_stream)
308 fprintf (loop_dump_stream,
309 "Unrolling failure: cannot unroll EH regions.\n");
315 if (block_begins != block_ends)
317 if (loop_dump_stream)
318 fprintf (loop_dump_stream,
319 "Unrolling failure: Unbalanced block notes.\n");
324 /* Determine type of unroll to perform. Depends on the number of iterations
325 and the size of the loop. */
327 /* If there is no strength reduce info, then set
328 loop_info->n_iterations to zero. This can happen if
329 strength_reduce can't find any bivs in the loop. A value of zero
330 indicates that the number of iterations could not be calculated. */
332 if (! strength_reduce_p)
333 loop_info->n_iterations = 0;
335 if (loop_dump_stream && loop_info->n_iterations > 0)
337 fputs ("Loop unrolling: ", loop_dump_stream);
338 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
339 loop_info->n_iterations);
340 fputs (" iterations.\n", loop_dump_stream);
343 /* Find and save a pointer to the last nonnote insn in the loop. */
345 last_loop_insn = prev_nonnote_insn (loop_end);
347 /* Calculate how many times to unroll the loop. Indicate whether or
348 not the loop is being completely unrolled. */
350 if (loop_info->n_iterations == 1)
352 /* Handle the case where the loop begins with an unconditional
353 jump to the loop condition. Make sure to delete the jump
354 insn, otherwise the loop body will never execute. */
356 rtx ujump = ujump_to_loop_cont (loop->start, loop->cont);
360 /* If number of iterations is exactly 1, then eliminate the compare and
361 branch at the end of the loop since they will never be taken.
362 Then return, since no other action is needed here. */
364 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
365 don't do anything. */
367 if (GET_CODE (last_loop_insn) == BARRIER)
369 /* Delete the jump insn. This will delete the barrier also. */
370 delete_insn (PREV_INSN (last_loop_insn));
372 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
375 rtx prev = PREV_INSN (last_loop_insn);
377 delete_insn (last_loop_insn);
379 /* The immediately preceding insn may be a compare which must be
381 if (sets_cc0_p (prev))
386 /* Remove the loop notes since this is no longer a loop. */
388 delete_insn (loop->vtop);
390 delete_insn (loop->cont);
392 delete_insn (loop_start);
394 delete_insn (loop_end);
398 else if (loop_info->n_iterations > 0
399 /* Avoid overflow in the next expression. */
400 && loop_info->n_iterations < MAX_UNROLLED_INSNS
401 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
403 unroll_number = loop_info->n_iterations;
404 unroll_type = UNROLL_COMPLETELY;
406 else if (loop_info->n_iterations > 0)
408 /* Try to factor the number of iterations. Don't bother with the
409 general case, only using 2, 3, 5, and 7 will get 75% of all
410 numbers theoretically, and almost all in practice. */
412 for (i = 0; i < NUM_FACTORS; i++)
413 factors[i].count = 0;
415 temp = loop_info->n_iterations;
416 for (i = NUM_FACTORS - 1; i >= 0; i--)
417 while (temp % factors[i].factor == 0)
420 temp = temp / factors[i].factor;
423 /* Start with the larger factors first so that we generally
424 get lots of unrolling. */
428 for (i = 3; i >= 0; i--)
429 while (factors[i].count--)
431 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
433 unroll_number *= factors[i].factor;
434 temp *= factors[i].factor;
440 /* If we couldn't find any factors, then unroll as in the normal
442 if (unroll_number == 1)
444 if (loop_dump_stream)
445 fprintf (loop_dump_stream,
446 "Loop unrolling: No factors found.\n");
449 unroll_type = UNROLL_MODULO;
453 /* Default case, calculate number of times to unroll loop based on its
455 if (unroll_type == UNROLL_NAIVE)
457 if (8 * insn_count < MAX_UNROLLED_INSNS)
459 else if (4 * insn_count < MAX_UNROLLED_INSNS)
465 /* Now we know how many times to unroll the loop. */
467 if (loop_dump_stream)
468 fprintf (loop_dump_stream,
469 "Unrolling loop %d times.\n", unroll_number);
472 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
474 /* Loops of these types can start with jump down to the exit condition
475 in rare circumstances.
477 Consider a pair of nested loops where the inner loop is part
478 of the exit code for the outer loop.
480 In this case jump.c will not duplicate the exit test for the outer
481 loop, so it will start with a jump to the exit code.
483 Then consider if the inner loop turns out to iterate once and
484 only once. We will end up deleting the jumps associated with
485 the inner loop. However, the loop notes are not removed from
486 the instruction stream.
488 And finally assume that we can compute the number of iterations
491 In this case unroll may want to unroll the outer loop even though
492 it starts with a jump to the outer loop's exit code.
494 We could try to optimize this case, but it hardly seems worth it.
495 Just return without unrolling the loop in such cases. */
498 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
499 insn = NEXT_INSN (insn);
500 if (GET_CODE (insn) == JUMP_INSN)
504 if (unroll_type == UNROLL_COMPLETELY)
506 /* Completely unrolling the loop: Delete the compare and branch at
507 the end (the last two instructions). This delete must done at the
508 very end of loop unrolling, to avoid problems with calls to
509 back_branch_in_range_p, which is called by find_splittable_regs.
510 All increments of splittable bivs/givs are changed to load constant
513 copy_start = loop_start;
515 /* Set insert_before to the instruction immediately after the JUMP_INSN
516 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
517 the loop will be correctly handled by copy_loop_body. */
518 insert_before = NEXT_INSN (last_loop_insn);
520 /* Set copy_end to the insn before the jump at the end of the loop. */
521 if (GET_CODE (last_loop_insn) == BARRIER)
522 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
523 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
525 copy_end = PREV_INSN (last_loop_insn);
527 /* The instruction immediately before the JUMP_INSN may be a compare
528 instruction which we do not want to copy. */
529 if (sets_cc0_p (PREV_INSN (copy_end)))
530 copy_end = PREV_INSN (copy_end);
535 /* We currently can't unroll a loop if it doesn't end with a
536 JUMP_INSN. There would need to be a mechanism that recognizes
537 this case, and then inserts a jump after each loop body, which
538 jumps to after the last loop body. */
539 if (loop_dump_stream)
540 fprintf (loop_dump_stream,
541 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
545 else if (unroll_type == UNROLL_MODULO)
547 /* Partially unrolling the loop: The compare and branch at the end
548 (the last two instructions) must remain. Don't copy the compare
549 and branch instructions at the end of the loop. Insert the unrolled
550 code immediately before the compare/branch at the end so that the
551 code will fall through to them as before. */
553 copy_start = loop_start;
555 /* Set insert_before to the jump insn at the end of the loop.
556 Set copy_end to before the jump insn at the end of the loop. */
557 if (GET_CODE (last_loop_insn) == BARRIER)
559 insert_before = PREV_INSN (last_loop_insn);
560 copy_end = PREV_INSN (insert_before);
562 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
564 insert_before = last_loop_insn;
566 /* The instruction immediately before the JUMP_INSN may be a compare
567 instruction which we do not want to copy or delete. */
568 if (sets_cc0_p (PREV_INSN (insert_before)))
569 insert_before = PREV_INSN (insert_before);
571 copy_end = PREV_INSN (insert_before);
575 /* We currently can't unroll a loop if it doesn't end with a
576 JUMP_INSN. There would need to be a mechanism that recognizes
577 this case, and then inserts a jump after each loop body, which
578 jumps to after the last loop body. */
579 if (loop_dump_stream)
580 fprintf (loop_dump_stream,
581 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
587 /* Normal case: Must copy the compare and branch instructions at the
590 if (GET_CODE (last_loop_insn) == BARRIER)
592 /* Loop ends with an unconditional jump and a barrier.
593 Handle this like above, don't copy jump and barrier.
594 This is not strictly necessary, but doing so prevents generating
595 unconditional jumps to an immediately following label.
597 This will be corrected below if the target of this jump is
598 not the start_label. */
600 insert_before = PREV_INSN (last_loop_insn);
601 copy_end = PREV_INSN (insert_before);
603 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
605 /* Set insert_before to immediately after the JUMP_INSN, so that
606 NOTEs at the end of the loop will be correctly handled by
608 insert_before = NEXT_INSN (last_loop_insn);
609 copy_end = last_loop_insn;
613 /* We currently can't unroll a loop if it doesn't end with a
614 JUMP_INSN. There would need to be a mechanism that recognizes
615 this case, and then inserts a jump after each loop body, which
616 jumps to after the last loop body. */
617 if (loop_dump_stream)
618 fprintf (loop_dump_stream,
619 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
623 /* If copying exit test branches because they can not be eliminated,
624 then must convert the fall through case of the branch to a jump past
625 the end of the loop. Create a label to emit after the loop and save
626 it for later use. Do not use the label after the loop, if any, since
627 it might be used by insns outside the loop, or there might be insns
628 added before it later by final_[bg]iv_value which must be after
629 the real exit label. */
630 exit_label = gen_label_rtx ();
633 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
634 insn = NEXT_INSN (insn);
636 if (GET_CODE (insn) == JUMP_INSN)
638 /* The loop starts with a jump down to the exit condition test.
639 Start copying the loop after the barrier following this
641 copy_start = NEXT_INSN (insn);
643 /* Splitting induction variables doesn't work when the loop is
644 entered via a jump to the bottom, because then we end up doing
645 a comparison against a new register for a split variable, but
646 we did not execute the set insn for the new register because
647 it was skipped over. */
648 splitting_not_safe = 1;
649 if (loop_dump_stream)
650 fprintf (loop_dump_stream,
651 "Splitting not safe, because loop not entered at top.\n");
654 copy_start = loop_start;
657 /* This should always be the first label in the loop. */
658 start_label = NEXT_INSN (copy_start);
659 /* There may be a line number note and/or a loop continue note here. */
660 while (GET_CODE (start_label) == NOTE)
661 start_label = NEXT_INSN (start_label);
662 if (GET_CODE (start_label) != CODE_LABEL)
664 /* This can happen as a result of jump threading. If the first insns in
665 the loop test the same condition as the loop's backward jump, or the
666 opposite condition, then the backward jump will be modified to point
667 to elsewhere, and the loop's start label is deleted.
669 This case currently can not be handled by the loop unrolling code. */
671 if (loop_dump_stream)
672 fprintf (loop_dump_stream,
673 "Unrolling failure: unknown insns between BEG note and loop label.\n");
676 if (LABEL_NAME (start_label))
678 /* The jump optimization pass must have combined the original start label
679 with a named label for a goto. We can't unroll this case because
680 jumps which go to the named label must be handled differently than
681 jumps to the loop start, and it is impossible to differentiate them
683 if (loop_dump_stream)
684 fprintf (loop_dump_stream,
685 "Unrolling failure: loop start label is gone\n");
689 if (unroll_type == UNROLL_NAIVE
690 && GET_CODE (last_loop_insn) == BARRIER
691 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
692 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
694 /* In this case, we must copy the jump and barrier, because they will
695 not be converted to jumps to an immediately following label. */
697 insert_before = NEXT_INSN (last_loop_insn);
698 copy_end = last_loop_insn;
701 if (unroll_type == UNROLL_NAIVE
702 && GET_CODE (last_loop_insn) == JUMP_INSN
703 && start_label != JUMP_LABEL (last_loop_insn))
705 /* ??? The loop ends with a conditional branch that does not branch back
706 to the loop start label. In this case, we must emit an unconditional
707 branch to the loop exit after emitting the final branch.
708 copy_loop_body does not have support for this currently, so we
709 give up. It doesn't seem worthwhile to unroll anyways since
710 unrolling would increase the number of branch instructions
712 if (loop_dump_stream)
713 fprintf (loop_dump_stream,
714 "Unrolling failure: final conditional branch not to loop start\n");
718 /* Allocate a translation table for the labels and insn numbers.
719 They will be filled in as we copy the insns in the loop. */
721 max_labelno = max_label_num ();
722 max_insnno = get_max_uid ();
724 /* Various paths through the unroll code may reach the "egress" label
725 without initializing fields within the map structure.
727 To be safe, we use xcalloc to zero the memory. */
728 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
730 /* Allocate the label map. */
734 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
736 local_label = (char *) xcalloc (max_labelno, sizeof (char));
739 /* Search the loop and mark all local labels, i.e. the ones which have to
740 be distinct labels when copied. For all labels which might be
741 non-local, set their label_map entries to point to themselves.
742 If they happen to be local their label_map entries will be overwritten
743 before the loop body is copied. The label_map entries for local labels
744 will be set to a different value each time the loop body is copied. */
746 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
750 if (GET_CODE (insn) == CODE_LABEL)
751 local_label[CODE_LABEL_NUMBER (insn)] = 1;
752 else if (GET_CODE (insn) == JUMP_INSN)
754 if (JUMP_LABEL (insn))
755 set_label_in_map (map,
756 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
758 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
759 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
761 rtx pat = PATTERN (insn);
762 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
763 int len = XVECLEN (pat, diff_vec_p);
766 for (i = 0; i < len; i++)
768 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
769 set_label_in_map (map,
770 CODE_LABEL_NUMBER (label),
775 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
776 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
780 /* Allocate space for the insn map. */
782 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
784 /* Set this to zero, to indicate that we are doing loop unrolling,
785 not function inlining. */
786 map->inline_target = 0;
788 /* The register and constant maps depend on the number of registers
789 present, so the final maps can't be created until after
790 find_splittable_regs is called. However, they are needed for
791 preconditioning, so we create temporary maps when preconditioning
794 /* The preconditioning code may allocate two new pseudo registers. */
795 maxregnum = max_reg_num ();
797 /* local_regno is only valid for regnos < max_local_regnum. */
798 max_local_regnum = maxregnum;
800 /* Allocate and zero out the splittable_regs and addr_combined_regs
801 arrays. These must be zeroed here because they will be used if
802 loop preconditioning is performed, and must be zero for that case.
804 It is safe to do this here, since the extra registers created by the
805 preconditioning code and find_splittable_regs will never be used
806 to access the splittable_regs[] and addr_combined_regs[] arrays. */
808 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
809 derived_regs = (char *) xcalloc (maxregnum, sizeof (char));
810 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
812 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
813 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
815 /* Mark all local registers, i.e. the ones which are referenced only
817 if (INSN_UID (copy_end) < max_uid_for_loop)
819 int copy_start_luid = INSN_LUID (copy_start);
820 int copy_end_luid = INSN_LUID (copy_end);
822 /* If a register is used in the jump insn, we must not duplicate it
823 since it will also be used outside the loop. */
824 if (GET_CODE (copy_end) == JUMP_INSN)
827 /* If we have a target that uses cc0, then we also must not duplicate
828 the insn that sets cc0 before the jump insn, if one is present. */
830 if (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
834 /* If copy_start points to the NOTE that starts the loop, then we must
835 use the next luid, because invariant pseudo-regs moved out of the loop
836 have their lifetimes modified to start here, but they are not safe
838 if (copy_start == loop_start)
841 /* If a pseudo's lifetime is entirely contained within this loop, then we
842 can use a different pseudo in each unrolled copy of the loop. This
843 results in better code. */
844 /* We must limit the generic test to max_reg_before_loop, because only
845 these pseudo registers have valid regno_first_uid info. */
846 for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r)
847 if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) <= max_uid_for_loop
848 && uid_luid[REGNO_FIRST_UID (r)] >= copy_start_luid
849 && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) <= max_uid_for_loop
850 && uid_luid[REGNO_LAST_UID (r)] <= copy_end_luid)
852 /* However, we must also check for loop-carried dependencies.
853 If the value the pseudo has at the end of iteration X is
854 used by iteration X+1, then we can not use a different pseudo
855 for each unrolled copy of the loop. */
856 /* A pseudo is safe if regno_first_uid is a set, and this
857 set dominates all instructions from regno_first_uid to
859 /* ??? This check is simplistic. We would get better code if
860 this check was more sophisticated. */
861 if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r),
862 copy_start, copy_end))
865 if (loop_dump_stream)
868 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
870 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
874 /* Givs that have been created from multiple biv increments always have
876 for (r = first_increment_giv; r <= last_increment_giv; r++)
879 if (loop_dump_stream)
880 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
884 /* If this loop requires exit tests when unrolled, check to see if we
885 can precondition the loop so as to make the exit tests unnecessary.
886 Just like variable splitting, this is not safe if the loop is entered
887 via a jump to the bottom. Also, can not do this if no strength
888 reduce info, because precondition_loop_p uses this info. */
890 /* Must copy the loop body for preconditioning before the following
891 find_splittable_regs call since that will emit insns which need to
892 be after the preconditioned loop copies, but immediately before the
893 unrolled loop copies. */
895 /* Also, it is not safe to split induction variables for the preconditioned
896 copies of the loop body. If we split induction variables, then the code
897 assumes that each induction variable can be represented as a function
898 of its initial value and the loop iteration number. This is not true
899 in this case, because the last preconditioned copy of the loop body
900 could be any iteration from the first up to the `unroll_number-1'th,
901 depending on the initial value of the iteration variable. Therefore
902 we can not split induction variables here, because we can not calculate
903 their value. Hence, this code must occur before find_splittable_regs
906 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
908 rtx initial_value, final_value, increment;
909 enum machine_mode mode;
911 if (precondition_loop_p (loop,
912 &initial_value, &final_value, &increment,
917 int abs_inc, neg_inc;
919 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
921 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
922 "unroll_loop_precondition");
923 global_const_equiv_varray = map->const_equiv_varray;
925 init_reg_map (map, maxregnum);
927 /* Limit loop unrolling to 4, since this will make 7 copies of
929 if (unroll_number > 4)
932 /* Save the absolute value of the increment, and also whether or
933 not it is negative. */
935 abs_inc = INTVAL (increment);
944 /* Calculate the difference between the final and initial values.
945 Final value may be a (plus (reg x) (const_int 1)) rtx.
946 Let the following cse pass simplify this if initial value is
949 We must copy the final and initial values here to avoid
950 improperly shared rtl. */
952 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
953 copy_rtx (initial_value), NULL_RTX, 0,
956 /* Now calculate (diff % (unroll * abs (increment))) by using an
958 diff = expand_binop (GET_MODE (diff), and_optab, diff,
959 GEN_INT (unroll_number * abs_inc - 1),
960 NULL_RTX, 0, OPTAB_LIB_WIDEN);
962 /* Now emit a sequence of branches to jump to the proper precond
965 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
966 for (i = 0; i < unroll_number; i++)
967 labels[i] = gen_label_rtx ();
969 /* Check for the case where the initial value is greater than or
970 equal to the final value. In that case, we want to execute
971 exactly one loop iteration. The code below will fail for this
972 case. This check does not apply if the loop has a NE
973 comparison at the end. */
975 if (loop_info->comparison_code != NE)
977 emit_cmp_and_jump_insns (initial_value, final_value,
979 NULL_RTX, mode, 0, 0, labels[1]);
980 JUMP_LABEL (get_last_insn ()) = labels[1];
981 LABEL_NUSES (labels[1])++;
984 /* Assuming the unroll_number is 4, and the increment is 2, then
985 for a negative increment: for a positive increment:
986 diff = 0,1 precond 0 diff = 0,7 precond 0
987 diff = 2,3 precond 3 diff = 1,2 precond 1
988 diff = 4,5 precond 2 diff = 3,4 precond 2
989 diff = 6,7 precond 1 diff = 5,6 precond 3 */
991 /* We only need to emit (unroll_number - 1) branches here, the
992 last case just falls through to the following code. */
994 /* ??? This would give better code if we emitted a tree of branches
995 instead of the current linear list of branches. */
997 for (i = 0; i < unroll_number - 1; i++)
1000 enum rtx_code cmp_code;
1002 /* For negative increments, must invert the constant compared
1003 against, except when comparing against zero. */
1011 cmp_const = unroll_number - i;
1020 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
1021 cmp_code, NULL_RTX, mode, 0, 0,
1023 JUMP_LABEL (get_last_insn ()) = labels[i];
1024 LABEL_NUSES (labels[i])++;
1027 /* If the increment is greater than one, then we need another branch,
1028 to handle other cases equivalent to 0. */
1030 /* ??? This should be merged into the code above somehow to help
1031 simplify the code here, and reduce the number of branches emitted.
1032 For the negative increment case, the branch here could easily
1033 be merged with the `0' case branch above. For the positive
1034 increment case, it is not clear how this can be simplified. */
1039 enum rtx_code cmp_code;
1043 cmp_const = abs_inc - 1;
1048 cmp_const = abs_inc * (unroll_number - 1) + 1;
1052 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1053 NULL_RTX, mode, 0, 0, labels[0]);
1054 JUMP_LABEL (get_last_insn ()) = labels[0];
1055 LABEL_NUSES (labels[0])++;
1058 sequence = gen_sequence ();
1060 emit_insn_before (sequence, loop_start);
1062 /* Only the last copy of the loop body here needs the exit
1063 test, so set copy_end to exclude the compare/branch here,
1064 and then reset it inside the loop when get to the last
1067 if (GET_CODE (last_loop_insn) == BARRIER)
1068 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1069 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1071 copy_end = PREV_INSN (last_loop_insn);
1073 /* The immediately preceding insn may be a compare which we do not
1075 if (sets_cc0_p (PREV_INSN (copy_end)))
1076 copy_end = PREV_INSN (copy_end);
1082 for (i = 1; i < unroll_number; i++)
1084 emit_label_after (labels[unroll_number - i],
1085 PREV_INSN (loop_start));
1087 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1088 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1089 (VARRAY_SIZE (map->const_equiv_varray)
1090 * sizeof (struct const_equiv_data)));
1093 for (j = 0; j < max_labelno; j++)
1095 set_label_in_map (map, j, gen_label_rtx ());
1097 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1101 = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1102 record_base_value (REGNO (map->reg_map[r]),
1103 regno_reg_rtx[r], 0);
1105 /* The last copy needs the compare/branch insns at the end,
1106 so reset copy_end here if the loop ends with a conditional
1109 if (i == unroll_number - 1)
1111 if (GET_CODE (last_loop_insn) == BARRIER)
1112 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1114 copy_end = last_loop_insn;
1117 /* None of the copies are the `last_iteration', so just
1118 pass zero for that parameter. */
1119 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1120 unroll_type, start_label, loop_end,
1121 loop_start, copy_end);
1123 emit_label_after (labels[0], PREV_INSN (loop_start));
1125 if (GET_CODE (last_loop_insn) == BARRIER)
1127 insert_before = PREV_INSN (last_loop_insn);
1128 copy_end = PREV_INSN (insert_before);
1132 insert_before = last_loop_insn;
1134 /* The instruction immediately before the JUMP_INSN may be a compare
1135 instruction which we do not want to copy or delete. */
1136 if (sets_cc0_p (PREV_INSN (insert_before)))
1137 insert_before = PREV_INSN (insert_before);
1139 copy_end = PREV_INSN (insert_before);
1142 /* Set unroll type to MODULO now. */
1143 unroll_type = UNROLL_MODULO;
1144 loop_preconditioned = 1;
1151 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1152 the loop unless all loops are being unrolled. */
1153 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1155 if (loop_dump_stream)
1156 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1160 /* At this point, we are guaranteed to unroll the loop. */
1162 /* Keep track of the unroll factor for the loop. */
1163 loop_info->unroll_number = unroll_number;
1165 /* For each biv and giv, determine whether it can be safely split into
1166 a different variable for each unrolled copy of the loop body.
1167 We precalculate and save this info here, since computing it is
1170 Do this before deleting any instructions from the loop, so that
1171 back_branch_in_range_p will work correctly. */
1173 if (splitting_not_safe)
1176 temp = find_splittable_regs (loop, unroll_type,
1177 end_insert_before, unroll_number);
1179 /* find_splittable_regs may have created some new registers, so must
1180 reallocate the reg_map with the new larger size, and must realloc
1181 the constant maps also. */
1183 maxregnum = max_reg_num ();
1184 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1186 init_reg_map (map, maxregnum);
1188 if (map->const_equiv_varray == 0)
1189 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1190 maxregnum + temp * unroll_number * 2,
1192 global_const_equiv_varray = map->const_equiv_varray;
1194 /* Search the list of bivs and givs to find ones which need to be remapped
1195 when split, and set their reg_map entry appropriately. */
1197 for (bl = loop_iv_list; bl; bl = bl->next)
1199 if (REGNO (bl->biv->src_reg) != bl->regno)
1200 map->reg_map[bl->regno] = bl->biv->src_reg;
1202 /* Currently, non-reduced/final-value givs are never split. */
1203 for (v = bl->giv; v; v = v->next_iv)
1204 if (REGNO (v->src_reg) != bl->regno)
1205 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1209 /* Use our current register alignment and pointer flags. */
1210 map->regno_pointer_flag = cfun->emit->regno_pointer_flag;
1211 map->regno_pointer_align = cfun->emit->regno_pointer_align;
1213 /* If the loop is being partially unrolled, and the iteration variables
1214 are being split, and are being renamed for the split, then must fix up
1215 the compare/jump instruction at the end of the loop to refer to the new
1216 registers. This compare isn't copied, so the registers used in it
1217 will never be replaced if it isn't done here. */
1219 if (unroll_type == UNROLL_MODULO)
1221 insn = NEXT_INSN (copy_end);
1222 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1223 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1226 /* For unroll_number times, make a copy of each instruction
1227 between copy_start and copy_end, and insert these new instructions
1228 before the end of the loop. */
1230 for (i = 0; i < unroll_number; i++)
1232 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1233 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1234 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1237 for (j = 0; j < max_labelno; j++)
1239 set_label_in_map (map, j, gen_label_rtx ());
1241 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1244 map->reg_map[r] = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1245 record_base_value (REGNO (map->reg_map[r]),
1246 regno_reg_rtx[r], 0);
1249 /* If loop starts with a branch to the test, then fix it so that
1250 it points to the test of the first unrolled copy of the loop. */
1251 if (i == 0 && loop_start != copy_start)
1253 insn = PREV_INSN (copy_start);
1254 pattern = PATTERN (insn);
1256 tem = get_label_from_map (map,
1258 (XEXP (SET_SRC (pattern), 0)));
1259 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1261 /* Set the jump label so that it can be used by later loop unrolling
1263 JUMP_LABEL (insn) = tem;
1264 LABEL_NUSES (tem)++;
1267 copy_loop_body (copy_start, copy_end, map, exit_label,
1268 i == unroll_number - 1, unroll_type, start_label,
1269 loop_end, insert_before, insert_before);
1272 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1273 insn to be deleted. This prevents any runaway delete_insn call from
1274 more insns that it should, as it always stops at a CODE_LABEL. */
1276 /* Delete the compare and branch at the end of the loop if completely
1277 unrolling the loop. Deleting the backward branch at the end also
1278 deletes the code label at the start of the loop. This is done at
1279 the very end to avoid problems with back_branch_in_range_p. */
1281 if (unroll_type == UNROLL_COMPLETELY)
1282 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1284 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1286 /* Delete all of the original loop instructions. Don't delete the
1287 LOOP_BEG note, or the first code label in the loop. */
1289 insn = NEXT_INSN (copy_start);
1290 while (insn != safety_label)
1292 /* ??? Don't delete named code labels. They will be deleted when the
1293 jump that references them is deleted. Otherwise, we end up deleting
1294 them twice, which causes them to completely disappear instead of turn
1295 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1296 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1297 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1298 associated LABEL_DECL to point to one of the new label instances. */
1299 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1300 if (insn != start_label
1301 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1302 && ! (GET_CODE (insn) == NOTE
1303 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1304 insn = delete_insn (insn);
1306 insn = NEXT_INSN (insn);
1309 /* Can now delete the 'safety' label emitted to protect us from runaway
1310 delete_insn calls. */
1311 if (INSN_DELETED_P (safety_label))
1313 delete_insn (safety_label);
1315 /* If exit_label exists, emit it after the loop. Doing the emit here
1316 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1317 This is needed so that mostly_true_jump in reorg.c will treat jumps
1318 to this loop end label correctly, i.e. predict that they are usually
1321 emit_label_after (exit_label, loop_end);
1324 if (unroll_type == UNROLL_COMPLETELY)
1326 /* Remove the loop notes since this is no longer a loop. */
1328 delete_insn (loop->vtop);
1330 delete_insn (loop->cont);
1332 delete_insn (loop_start);
1334 delete_insn (loop_end);
1337 if (map->const_equiv_varray)
1338 VARRAY_FREE (map->const_equiv_varray);
1341 free (map->label_map);
1344 free (map->insn_map);
1345 free (splittable_regs);
1346 free (derived_regs);
1347 free (splittable_regs_updates);
1348 free (addr_combined_regs);
1351 free (map->reg_map);
1355 /* Return true if the loop can be safely, and profitably, preconditioned
1356 so that the unrolled copies of the loop body don't need exit tests.
1358 This only works if final_value, initial_value and increment can be
1359 determined, and if increment is a constant power of 2.
1360 If increment is not a power of 2, then the preconditioning modulo
1361 operation would require a real modulo instead of a boolean AND, and this
1362 is not considered `profitable'. */
1364 /* ??? If the loop is known to be executed very many times, or the machine
1365 has a very cheap divide instruction, then preconditioning is a win even
1366 when the increment is not a power of 2. Use RTX_COST to compute
1367 whether divide is cheap.
1368 ??? A divide by constant doesn't actually need a divide, look at
1369 expand_divmod. The reduced cost of this optimized modulo is not
1370 reflected in RTX_COST. */
1373 precondition_loop_p (loop, initial_value, final_value, increment, mode)
1374 const struct loop *loop;
1375 rtx *initial_value, *final_value, *increment;
1376 enum machine_mode *mode;
1378 rtx loop_start = loop->start;
1379 struct loop_info *loop_info = LOOP_INFO (loop);
1381 if (loop_info->n_iterations > 0)
1383 *initial_value = const0_rtx;
1384 *increment = const1_rtx;
1385 *final_value = GEN_INT (loop_info->n_iterations);
1388 if (loop_dump_stream)
1390 fputs ("Preconditioning: Success, number of iterations known, ",
1392 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1393 loop_info->n_iterations);
1394 fputs (".\n", loop_dump_stream);
1399 if (loop_info->initial_value == 0)
1401 if (loop_dump_stream)
1402 fprintf (loop_dump_stream,
1403 "Preconditioning: Could not find initial value.\n");
1406 else if (loop_info->increment == 0)
1408 if (loop_dump_stream)
1409 fprintf (loop_dump_stream,
1410 "Preconditioning: Could not find increment value.\n");
1413 else if (GET_CODE (loop_info->increment) != CONST_INT)
1415 if (loop_dump_stream)
1416 fprintf (loop_dump_stream,
1417 "Preconditioning: Increment not a constant.\n");
1420 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1421 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1423 if (loop_dump_stream)
1424 fprintf (loop_dump_stream,
1425 "Preconditioning: Increment not a constant power of 2.\n");
1429 /* Unsigned_compare and compare_dir can be ignored here, since they do
1430 not matter for preconditioning. */
1432 if (loop_info->final_value == 0)
1434 if (loop_dump_stream)
1435 fprintf (loop_dump_stream,
1436 "Preconditioning: EQ comparison loop.\n");
1440 /* Must ensure that final_value is invariant, so call
1441 loop_invariant_p to check. Before doing so, must check regno
1442 against max_reg_before_loop to make sure that the register is in
1443 the range covered by loop_invariant_p. If it isn't, then it is
1444 most likely a biv/giv which by definition are not invariant. */
1445 if ((GET_CODE (loop_info->final_value) == REG
1446 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1447 || (GET_CODE (loop_info->final_value) == PLUS
1448 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1449 || ! loop_invariant_p (loop, loop_info->final_value))
1451 if (loop_dump_stream)
1452 fprintf (loop_dump_stream,
1453 "Preconditioning: Final value not invariant.\n");
1457 /* Fail for floating point values, since the caller of this function
1458 does not have code to deal with them. */
1459 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1460 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1462 if (loop_dump_stream)
1463 fprintf (loop_dump_stream,
1464 "Preconditioning: Floating point final or initial value.\n");
1468 /* Fail if loop_info->iteration_var is not live before loop_start,
1469 since we need to test its value in the preconditioning code. */
1471 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1472 > INSN_LUID (loop_start))
1474 if (loop_dump_stream)
1475 fprintf (loop_dump_stream,
1476 "Preconditioning: Iteration var not live before loop start.\n");
1480 /* Note that iteration_info biases the initial value for GIV iterators
1481 such as "while (i-- > 0)" so that we can calculate the number of
1482 iterations just like for BIV iterators.
1484 Also note that the absolute values of initial_value and
1485 final_value are unimportant as only their difference is used for
1486 calculating the number of loop iterations. */
1487 *initial_value = loop_info->initial_value;
1488 *increment = loop_info->increment;
1489 *final_value = loop_info->final_value;
1491 /* Decide what mode to do these calculations in. Choose the larger
1492 of final_value's mode and initial_value's mode, or a full-word if
1493 both are constants. */
1494 *mode = GET_MODE (*final_value);
1495 if (*mode == VOIDmode)
1497 *mode = GET_MODE (*initial_value);
1498 if (*mode == VOIDmode)
1501 else if (*mode != GET_MODE (*initial_value)
1502 && (GET_MODE_SIZE (*mode)
1503 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1504 *mode = GET_MODE (*initial_value);
1507 if (loop_dump_stream)
1508 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1513 /* All pseudo-registers must be mapped to themselves. Two hard registers
1514 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1515 REGNUM, to avoid function-inlining specific conversions of these
1516 registers. All other hard regs can not be mapped because they may be
1521 init_reg_map (map, maxregnum)
1522 struct inline_remap *map;
1527 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1528 map->reg_map[i] = regno_reg_rtx[i];
1529 /* Just clear the rest of the entries. */
1530 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1531 map->reg_map[i] = 0;
1533 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1534 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1535 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1536 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1539 /* Strength-reduction will often emit code for optimized biv/givs which
1540 calculates their value in a temporary register, and then copies the result
1541 to the iv. This procedure reconstructs the pattern computing the iv;
1542 verifying that all operands are of the proper form.
1544 PATTERN must be the result of single_set.
1545 The return value is the amount that the giv is incremented by. */
1548 calculate_giv_inc (pattern, src_insn, regno)
1549 rtx pattern, src_insn;
1553 rtx increment_total = 0;
1557 /* Verify that we have an increment insn here. First check for a plus
1558 as the set source. */
1559 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1561 /* SR sometimes computes the new giv value in a temp, then copies it
1563 src_insn = PREV_INSN (src_insn);
1564 pattern = PATTERN (src_insn);
1565 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1568 /* The last insn emitted is not needed, so delete it to avoid confusing
1569 the second cse pass. This insn sets the giv unnecessarily. */
1570 delete_insn (get_last_insn ());
1573 /* Verify that we have a constant as the second operand of the plus. */
1574 increment = XEXP (SET_SRC (pattern), 1);
1575 if (GET_CODE (increment) != CONST_INT)
1577 /* SR sometimes puts the constant in a register, especially if it is
1578 too big to be an add immed operand. */
1579 src_insn = PREV_INSN (src_insn);
1580 increment = SET_SRC (PATTERN (src_insn));
1582 /* SR may have used LO_SUM to compute the constant if it is too large
1583 for a load immed operand. In this case, the constant is in operand
1584 one of the LO_SUM rtx. */
1585 if (GET_CODE (increment) == LO_SUM)
1586 increment = XEXP (increment, 1);
1588 /* Some ports store large constants in memory and add a REG_EQUAL
1589 note to the store insn. */
1590 else if (GET_CODE (increment) == MEM)
1592 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1594 increment = XEXP (note, 0);
1597 else if (GET_CODE (increment) == IOR
1598 || GET_CODE (increment) == ASHIFT
1599 || GET_CODE (increment) == PLUS)
1601 /* The rs6000 port loads some constants with IOR.
1602 The alpha port loads some constants with ASHIFT and PLUS. */
1603 rtx second_part = XEXP (increment, 1);
1604 enum rtx_code code = GET_CODE (increment);
1606 src_insn = PREV_INSN (src_insn);
1607 increment = SET_SRC (PATTERN (src_insn));
1608 /* Don't need the last insn anymore. */
1609 delete_insn (get_last_insn ());
1611 if (GET_CODE (second_part) != CONST_INT
1612 || GET_CODE (increment) != CONST_INT)
1616 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1617 else if (code == PLUS)
1618 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1620 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1623 if (GET_CODE (increment) != CONST_INT)
1626 /* The insn loading the constant into a register is no longer needed,
1628 delete_insn (get_last_insn ());
1631 if (increment_total)
1632 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1634 increment_total = increment;
1636 /* Check that the source register is the same as the register we expected
1637 to see as the source. If not, something is seriously wrong. */
1638 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1639 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1641 /* Some machines (e.g. the romp), may emit two add instructions for
1642 certain constants, so lets try looking for another add immediately
1643 before this one if we have only seen one add insn so far. */
1649 src_insn = PREV_INSN (src_insn);
1650 pattern = PATTERN (src_insn);
1652 delete_insn (get_last_insn ());
1660 return increment_total;
1663 /* Copy REG_NOTES, except for insn references, because not all insn_map
1664 entries are valid yet. We do need to copy registers now though, because
1665 the reg_map entries can change during copying. */
1668 initial_reg_note_copy (notes, map)
1670 struct inline_remap *map;
1677 copy = rtx_alloc (GET_CODE (notes));
1678 PUT_MODE (copy, GET_MODE (notes));
1680 if (GET_CODE (notes) == EXPR_LIST)
1681 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1682 else if (GET_CODE (notes) == INSN_LIST)
1683 /* Don't substitute for these yet. */
1684 XEXP (copy, 0) = XEXP (notes, 0);
1688 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1693 /* Fixup insn references in copied REG_NOTES. */
1696 final_reg_note_copy (notes, map)
1698 struct inline_remap *map;
1702 for (note = notes; note; note = XEXP (note, 1))
1703 if (GET_CODE (note) == INSN_LIST)
1704 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1707 /* Copy each instruction in the loop, substituting from map as appropriate.
1708 This is very similar to a loop in expand_inline_function. */
1711 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1712 unroll_type, start_label, loop_end, insert_before,
1714 rtx copy_start, copy_end;
1715 struct inline_remap *map;
1718 enum unroll_types unroll_type;
1719 rtx start_label, loop_end, insert_before, copy_notes_from;
1722 rtx set, tem, copy = NULL_RTX;
1723 int dest_reg_was_split, i;
1727 rtx final_label = 0;
1728 rtx giv_inc, giv_dest_reg, giv_src_reg;
1730 /* If this isn't the last iteration, then map any references to the
1731 start_label to final_label. Final label will then be emitted immediately
1732 after the end of this loop body if it was ever used.
1734 If this is the last iteration, then map references to the start_label
1736 if (! last_iteration)
1738 final_label = gen_label_rtx ();
1739 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1743 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1747 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1748 Else gen_sequence could return a raw pattern for a jump which we pass
1749 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1750 a variety of losing behaviors later. */
1751 emit_note (0, NOTE_INSN_DELETED);
1756 insn = NEXT_INSN (insn);
1758 map->orig_asm_operands_vector = 0;
1760 switch (GET_CODE (insn))
1763 pattern = PATTERN (insn);
1767 /* Check to see if this is a giv that has been combined with
1768 some split address givs. (Combined in the sense that
1769 `combine_givs' in loop.c has put two givs in the same register.)
1770 In this case, we must search all givs based on the same biv to
1771 find the address givs. Then split the address givs.
1772 Do this before splitting the giv, since that may map the
1773 SET_DEST to a new register. */
1775 if ((set = single_set (insn))
1776 && GET_CODE (SET_DEST (set)) == REG
1777 && addr_combined_regs[REGNO (SET_DEST (set))])
1779 struct iv_class *bl;
1780 struct induction *v, *tv;
1781 unsigned int regno = REGNO (SET_DEST (set));
1783 v = addr_combined_regs[REGNO (SET_DEST (set))];
1784 bl = reg_biv_class[REGNO (v->src_reg)];
1786 /* Although the giv_inc amount is not needed here, we must call
1787 calculate_giv_inc here since it might try to delete the
1788 last insn emitted. If we wait until later to call it,
1789 we might accidentally delete insns generated immediately
1790 below by emit_unrolled_add. */
1792 if (! derived_regs[regno])
1793 giv_inc = calculate_giv_inc (set, insn, regno);
1795 /* Now find all address giv's that were combined with this
1797 for (tv = bl->giv; tv; tv = tv->next_iv)
1798 if (tv->giv_type == DEST_ADDR && tv->same == v)
1802 /* If this DEST_ADDR giv was not split, then ignore it. */
1803 if (*tv->location != tv->dest_reg)
1806 /* Scale this_giv_inc if the multiplicative factors of
1807 the two givs are different. */
1808 this_giv_inc = INTVAL (giv_inc);
1809 if (tv->mult_val != v->mult_val)
1810 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1811 * INTVAL (tv->mult_val));
1813 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1814 *tv->location = tv->dest_reg;
1816 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1818 /* Must emit an insn to increment the split address
1819 giv. Add in the const_adjust field in case there
1820 was a constant eliminated from the address. */
1821 rtx value, dest_reg;
1823 /* tv->dest_reg will be either a bare register,
1824 or else a register plus a constant. */
1825 if (GET_CODE (tv->dest_reg) == REG)
1826 dest_reg = tv->dest_reg;
1828 dest_reg = XEXP (tv->dest_reg, 0);
1830 /* Check for shared address givs, and avoid
1831 incrementing the shared pseudo reg more than
1833 if (! tv->same_insn && ! tv->shared)
1835 /* tv->dest_reg may actually be a (PLUS (REG)
1836 (CONST)) here, so we must call plus_constant
1837 to add the const_adjust amount before calling
1838 emit_unrolled_add below. */
1839 value = plus_constant (tv->dest_reg,
1842 if (GET_CODE (value) == PLUS)
1844 /* The constant could be too large for an add
1845 immediate, so can't directly emit an insn
1847 emit_unrolled_add (dest_reg, XEXP (value, 0),
1852 /* Reset the giv to be just the register again, in case
1853 it is used after the set we have just emitted.
1854 We must subtract the const_adjust factor added in
1856 tv->dest_reg = plus_constant (dest_reg,
1857 - tv->const_adjust);
1858 *tv->location = tv->dest_reg;
1863 /* If this is a setting of a splittable variable, then determine
1864 how to split the variable, create a new set based on this split,
1865 and set up the reg_map so that later uses of the variable will
1866 use the new split variable. */
1868 dest_reg_was_split = 0;
1870 if ((set = single_set (insn))
1871 && GET_CODE (SET_DEST (set)) == REG
1872 && splittable_regs[REGNO (SET_DEST (set))])
1874 unsigned int regno = REGNO (SET_DEST (set));
1875 unsigned int src_regno;
1877 dest_reg_was_split = 1;
1879 giv_dest_reg = SET_DEST (set);
1880 if (derived_regs[regno])
1882 /* ??? This relies on SET_SRC (SET) to be of
1883 the form (plus (reg) (const_int)), and thus
1884 forces recombine_givs to restrict the kind
1885 of giv derivations it does before unrolling. */
1886 giv_src_reg = XEXP (SET_SRC (set), 0);
1887 giv_inc = XEXP (SET_SRC (set), 1);
1891 giv_src_reg = giv_dest_reg;
1892 /* Compute the increment value for the giv, if it wasn't
1893 already computed above. */
1895 giv_inc = calculate_giv_inc (set, insn, regno);
1897 src_regno = REGNO (giv_src_reg);
1899 if (unroll_type == UNROLL_COMPLETELY)
1901 /* Completely unrolling the loop. Set the induction
1902 variable to a known constant value. */
1904 /* The value in splittable_regs may be an invariant
1905 value, so we must use plus_constant here. */
1906 splittable_regs[regno]
1907 = plus_constant (splittable_regs[src_regno],
1910 if (GET_CODE (splittable_regs[regno]) == PLUS)
1912 giv_src_reg = XEXP (splittable_regs[regno], 0);
1913 giv_inc = XEXP (splittable_regs[regno], 1);
1917 /* The splittable_regs value must be a REG or a
1918 CONST_INT, so put the entire value in the giv_src_reg
1920 giv_src_reg = splittable_regs[regno];
1921 giv_inc = const0_rtx;
1926 /* Partially unrolling loop. Create a new pseudo
1927 register for the iteration variable, and set it to
1928 be a constant plus the original register. Except
1929 on the last iteration, when the result has to
1930 go back into the original iteration var register. */
1932 /* Handle bivs which must be mapped to a new register
1933 when split. This happens for bivs which need their
1934 final value set before loop entry. The new register
1935 for the biv was stored in the biv's first struct
1936 induction entry by find_splittable_regs. */
1938 if (regno < max_reg_before_loop
1939 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1941 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1942 giv_dest_reg = giv_src_reg;
1946 /* If non-reduced/final-value givs were split, then
1947 this would have to remap those givs also. See
1948 find_splittable_regs. */
1951 splittable_regs[regno]
1952 = simplify_gen_binary (PLUS, GET_MODE (giv_src_reg),
1954 splittable_regs[src_regno]);
1955 giv_inc = splittable_regs[regno];
1957 /* Now split the induction variable by changing the dest
1958 of this insn to a new register, and setting its
1959 reg_map entry to point to this new register.
1961 If this is the last iteration, and this is the last insn
1962 that will update the iv, then reuse the original dest,
1963 to ensure that the iv will have the proper value when
1964 the loop exits or repeats.
1966 Using splittable_regs_updates here like this is safe,
1967 because it can only be greater than one if all
1968 instructions modifying the iv are always executed in
1971 if (! last_iteration
1972 || (splittable_regs_updates[regno]-- != 1))
1974 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1976 map->reg_map[regno] = tem;
1977 record_base_value (REGNO (tem),
1978 giv_inc == const0_rtx
1980 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1981 giv_src_reg, giv_inc),
1985 map->reg_map[regno] = giv_src_reg;
1988 /* The constant being added could be too large for an add
1989 immediate, so can't directly emit an insn here. */
1990 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1991 copy = get_last_insn ();
1992 pattern = PATTERN (copy);
1996 pattern = copy_rtx_and_substitute (pattern, map, 0);
1997 copy = emit_insn (pattern);
1999 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2002 /* If this insn is setting CC0, it may need to look at
2003 the insn that uses CC0 to see what type of insn it is.
2004 In that case, the call to recog via validate_change will
2005 fail. So don't substitute constants here. Instead,
2006 do it when we emit the following insn.
2008 For example, see the pyr.md file. That machine has signed and
2009 unsigned compares. The compare patterns must check the
2010 following branch insn to see which what kind of compare to
2013 If the previous insn set CC0, substitute constants on it as
2015 if (sets_cc0_p (PATTERN (copy)) != 0)
2020 try_constants (cc0_insn, map);
2022 try_constants (copy, map);
2025 try_constants (copy, map);
2028 /* Make split induction variable constants `permanent' since we
2029 know there are no backward branches across iteration variable
2030 settings which would invalidate this. */
2031 if (dest_reg_was_split)
2033 int regno = REGNO (SET_DEST (set));
2035 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
2036 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
2038 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
2043 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2044 copy = emit_jump_insn (pattern);
2045 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2047 if (JUMP_LABEL (insn) == start_label && insn == copy_end
2048 && ! last_iteration)
2050 /* Update JUMP_LABEL correctly to make invert_jump working. */
2051 JUMP_LABEL (copy) = get_label_from_map (map,
2053 (JUMP_LABEL (insn)));
2054 /* This is a branch to the beginning of the loop; this is the
2055 last insn being copied; and this is not the last iteration.
2056 In this case, we want to change the original fall through
2057 case to be a branch past the end of the loop, and the
2058 original jump label case to fall_through. */
2060 if (!invert_jump (copy, exit_label, 0))
2063 rtx lab = gen_label_rtx ();
2064 /* Can't do it by reversing the jump (probably because we
2065 couldn't reverse the conditions), so emit a new
2066 jump_insn after COPY, and redirect the jump around
2068 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2069 jmp = emit_barrier_after (jmp);
2070 emit_label_after (lab, jmp);
2071 LABEL_NUSES (lab) = 0;
2072 if (!redirect_jump (copy, lab, 0))
2079 try_constants (cc0_insn, map);
2082 try_constants (copy, map);
2084 /* Set the jump label of COPY correctly to avoid problems with
2085 later passes of unroll_loop, if INSN had jump label set. */
2086 if (JUMP_LABEL (insn))
2090 /* Can't use the label_map for every insn, since this may be
2091 the backward branch, and hence the label was not mapped. */
2092 if ((set = single_set (copy)))
2094 tem = SET_SRC (set);
2095 if (GET_CODE (tem) == LABEL_REF)
2096 label = XEXP (tem, 0);
2097 else if (GET_CODE (tem) == IF_THEN_ELSE)
2099 if (XEXP (tem, 1) != pc_rtx)
2100 label = XEXP (XEXP (tem, 1), 0);
2102 label = XEXP (XEXP (tem, 2), 0);
2106 if (label && GET_CODE (label) == CODE_LABEL)
2107 JUMP_LABEL (copy) = label;
2110 /* An unrecognizable jump insn, probably the entry jump
2111 for a switch statement. This label must have been mapped,
2112 so just use the label_map to get the new jump label. */
2114 = get_label_from_map (map,
2115 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2118 /* If this is a non-local jump, then must increase the label
2119 use count so that the label will not be deleted when the
2120 original jump is deleted. */
2121 LABEL_NUSES (JUMP_LABEL (copy))++;
2123 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2124 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2126 rtx pat = PATTERN (copy);
2127 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2128 int len = XVECLEN (pat, diff_vec_p);
2131 for (i = 0; i < len; i++)
2132 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2135 /* If this used to be a conditional jump insn but whose branch
2136 direction is now known, we must do something special. */
2137 if (any_condjump_p (insn) && onlyjump_p (insn) && map->last_pc_value)
2140 /* If the previous insn set cc0 for us, delete it. */
2141 if (sets_cc0_p (PREV_INSN (copy)))
2142 delete_insn (PREV_INSN (copy));
2145 /* If this is now a no-op, delete it. */
2146 if (map->last_pc_value == pc_rtx)
2148 /* Don't let delete_insn delete the label referenced here,
2149 because we might possibly need it later for some other
2150 instruction in the loop. */
2151 if (JUMP_LABEL (copy))
2152 LABEL_NUSES (JUMP_LABEL (copy))++;
2154 if (JUMP_LABEL (copy))
2155 LABEL_NUSES (JUMP_LABEL (copy))--;
2159 /* Otherwise, this is unconditional jump so we must put a
2160 BARRIER after it. We could do some dead code elimination
2161 here, but jump.c will do it just as well. */
2167 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2168 copy = emit_call_insn (pattern);
2169 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2171 /* Because the USAGE information potentially contains objects other
2172 than hard registers, we need to copy it. */
2173 CALL_INSN_FUNCTION_USAGE (copy)
2174 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2179 try_constants (cc0_insn, map);
2182 try_constants (copy, map);
2184 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2185 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2186 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2190 /* If this is the loop start label, then we don't need to emit a
2191 copy of this label since no one will use it. */
2193 if (insn != start_label)
2195 copy = emit_label (get_label_from_map (map,
2196 CODE_LABEL_NUMBER (insn)));
2202 copy = emit_barrier ();
2206 /* VTOP and CONT notes are valid only before the loop exit test.
2207 If placed anywhere else, loop may generate bad code. */
2208 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2209 the associated rtl. We do not want to share the structure in
2212 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2213 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED_LABEL
2214 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2215 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2216 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2217 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2218 copy = emit_note (NOTE_SOURCE_FILE (insn),
2219 NOTE_LINE_NUMBER (insn));
2228 map->insn_map[INSN_UID (insn)] = copy;
2230 while (insn != copy_end);
2232 /* Now finish coping the REG_NOTES. */
2236 insn = NEXT_INSN (insn);
2237 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2238 || GET_CODE (insn) == CALL_INSN)
2239 && map->insn_map[INSN_UID (insn)])
2240 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2242 while (insn != copy_end);
2244 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2245 each of these notes here, since there may be some important ones, such as
2246 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2247 iteration, because the original notes won't be deleted.
2249 We can't use insert_before here, because when from preconditioning,
2250 insert_before points before the loop. We can't use copy_end, because
2251 there may be insns already inserted after it (which we don't want to
2252 copy) when not from preconditioning code. */
2254 if (! last_iteration)
2256 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2258 /* VTOP notes are valid only before the loop exit test.
2259 If placed anywhere else, loop may generate bad code.
2260 There is no need to test for NOTE_INSN_LOOP_CONT notes
2261 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2262 instructions before the last insn in the loop, and if the
2263 end test is that short, there will be a VTOP note between
2264 the CONT note and the test. */
2265 if (GET_CODE (insn) == NOTE
2266 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2267 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2268 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2269 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2273 if (final_label && LABEL_NUSES (final_label) > 0)
2274 emit_label (final_label);
2276 tem = gen_sequence ();
2278 emit_insn_before (tem, insert_before);
2281 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2282 emitted. This will correctly handle the case where the increment value
2283 won't fit in the immediate field of a PLUS insns. */
2286 emit_unrolled_add (dest_reg, src_reg, increment)
2287 rtx dest_reg, src_reg, increment;
2291 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2292 dest_reg, 0, OPTAB_LIB_WIDEN);
2294 if (dest_reg != result)
2295 emit_move_insn (dest_reg, result);
2298 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2299 is a backward branch in that range that branches to somewhere between
2300 LOOP->START and INSN. Returns 0 otherwise. */
2302 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2303 In practice, this is not a problem, because this function is seldom called,
2304 and uses a negligible amount of CPU time on average. */
2307 back_branch_in_range_p (loop, insn)
2308 const struct loop *loop;
2311 rtx p, q, target_insn;
2312 rtx loop_start = loop->start;
2313 rtx loop_end = loop->end;
2314 rtx orig_loop_end = loop->end;
2316 /* Stop before we get to the backward branch at the end of the loop. */
2317 loop_end = prev_nonnote_insn (loop_end);
2318 if (GET_CODE (loop_end) == BARRIER)
2319 loop_end = PREV_INSN (loop_end);
2321 /* Check in case insn has been deleted, search forward for first non
2322 deleted insn following it. */
2323 while (INSN_DELETED_P (insn))
2324 insn = NEXT_INSN (insn);
2326 /* Check for the case where insn is the last insn in the loop. Deal
2327 with the case where INSN was a deleted loop test insn, in which case
2328 it will now be the NOTE_LOOP_END. */
2329 if (insn == loop_end || insn == orig_loop_end)
2332 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2334 if (GET_CODE (p) == JUMP_INSN)
2336 target_insn = JUMP_LABEL (p);
2338 /* Search from loop_start to insn, to see if one of them is
2339 the target_insn. We can't use INSN_LUID comparisons here,
2340 since insn may not have an LUID entry. */
2341 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2342 if (q == target_insn)
2350 /* Try to generate the simplest rtx for the expression
2351 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2355 fold_rtx_mult_add (mult1, mult2, add1, mode)
2356 rtx mult1, mult2, add1;
2357 enum machine_mode mode;
2362 /* The modes must all be the same. This should always be true. For now,
2363 check to make sure. */
2364 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2365 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2366 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2369 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2370 will be a constant. */
2371 if (GET_CODE (mult1) == CONST_INT)
2378 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2380 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2382 /* Again, put the constant second. */
2383 if (GET_CODE (add1) == CONST_INT)
2390 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2392 result = gen_rtx_PLUS (mode, add1, mult_res);
2397 /* Searches the list of induction struct's for the biv BL, to try to calculate
2398 the total increment value for one iteration of the loop as a constant.
2400 Returns the increment value as an rtx, simplified as much as possible,
2401 if it can be calculated. Otherwise, returns 0. */
2404 biv_total_increment (bl)
2405 struct iv_class *bl;
2407 struct induction *v;
2410 /* For increment, must check every instruction that sets it. Each
2411 instruction must be executed only once each time through the loop.
2412 To verify this, we check that the insn is always executed, and that
2413 there are no backward branches after the insn that branch to before it.
2414 Also, the insn must have a mult_val of one (to make sure it really is
2417 result = const0_rtx;
2418 for (v = bl->biv; v; v = v->next_iv)
2420 if (v->always_computable && v->mult_val == const1_rtx
2421 && ! v->maybe_multiple)
2422 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2430 /* Determine the initial value of the iteration variable, and the amount
2431 that it is incremented each loop. Use the tables constructed by
2432 the strength reduction pass to calculate these values.
2434 Initial_value and/or increment are set to zero if their values could not
2438 iteration_info (loop, iteration_var, initial_value, increment)
2439 const struct loop *loop ATTRIBUTE_UNUSED;
2440 rtx iteration_var, *initial_value, *increment;
2442 struct iv_class *bl;
2444 /* Clear the result values, in case no answer can be found. */
2448 /* The iteration variable can be either a giv or a biv. Check to see
2449 which it is, and compute the variable's initial value, and increment
2450 value if possible. */
2452 /* If this is a new register, can't handle it since we don't have any
2453 reg_iv_type entry for it. */
2454 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
2456 if (loop_dump_stream)
2457 fprintf (loop_dump_stream,
2458 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2462 /* Reject iteration variables larger than the host wide int size, since they
2463 could result in a number of iterations greater than the range of our
2464 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2465 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2466 > HOST_BITS_PER_WIDE_INT))
2468 if (loop_dump_stream)
2469 fprintf (loop_dump_stream,
2470 "Loop unrolling: Iteration var rejected because mode too large.\n");
2473 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2475 if (loop_dump_stream)
2476 fprintf (loop_dump_stream,
2477 "Loop unrolling: Iteration var not an integer.\n");
2480 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2482 /* When reg_iv_type / reg_iv_info is resized for biv increments
2483 that are turned into givs, reg_biv_class is not resized.
2484 So check here that we don't make an out-of-bounds access. */
2485 if (REGNO (iteration_var) >= max_reg_before_loop)
2488 /* Grab initial value, only useful if it is a constant. */
2489 bl = reg_biv_class[REGNO (iteration_var)];
2490 *initial_value = bl->initial_value;
2492 *increment = biv_total_increment (bl);
2494 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2496 HOST_WIDE_INT offset = 0;
2497 struct induction *v = REG_IV_INFO (REGNO (iteration_var));
2498 rtx biv_initial_value;
2500 if (REGNO (v->src_reg) >= max_reg_before_loop)
2503 bl = reg_biv_class[REGNO (v->src_reg)];
2505 /* Increment value is mult_val times the increment value of the biv. */
2507 *increment = biv_total_increment (bl);
2510 struct induction *biv_inc;
2513 = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, v->mode);
2514 /* The caller assumes that one full increment has occured at the
2515 first loop test. But that's not true when the biv is incremented
2516 after the giv is set (which is the usual case), e.g.:
2517 i = 6; do {;} while (i++ < 9) .
2518 Therefore, we bias the initial value by subtracting the amount of
2519 the increment that occurs between the giv set and the giv test. */
2520 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
2522 if (loop_insn_first_p (v->insn, biv_inc->insn))
2523 offset -= INTVAL (biv_inc->add_val);
2525 offset *= INTVAL (v->mult_val);
2527 if (loop_dump_stream)
2528 fprintf (loop_dump_stream,
2529 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2532 /* Initial value is mult_val times the biv's initial value plus
2533 add_val. Only useful if it is a constant. */
2534 biv_initial_value = extend_value_for_giv (v, bl->initial_value);
2536 = fold_rtx_mult_add (v->mult_val,
2537 plus_constant (biv_initial_value, offset),
2538 v->add_val, v->mode);
2542 if (loop_dump_stream)
2543 fprintf (loop_dump_stream,
2544 "Loop unrolling: Not basic or general induction var.\n");
2550 /* For each biv and giv, determine whether it can be safely split into
2551 a different variable for each unrolled copy of the loop body. If it
2552 is safe to split, then indicate that by saving some useful info
2553 in the splittable_regs array.
2555 If the loop is being completely unrolled, then splittable_regs will hold
2556 the current value of the induction variable while the loop is unrolled.
2557 It must be set to the initial value of the induction variable here.
2558 Otherwise, splittable_regs will hold the difference between the current
2559 value of the induction variable and the value the induction variable had
2560 at the top of the loop. It must be set to the value 0 here.
2562 Returns the total number of instructions that set registers that are
2565 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2566 constant values are unnecessary, since we can easily calculate increment
2567 values in this case even if nothing is constant. The increment value
2568 should not involve a multiply however. */
2570 /* ?? Even if the biv/giv increment values aren't constant, it may still
2571 be beneficial to split the variable if the loop is only unrolled a few
2572 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2575 find_splittable_regs (loop, unroll_type, end_insert_before, unroll_number)
2576 const struct loop *loop;
2577 enum unroll_types unroll_type;
2578 rtx end_insert_before;
2581 struct iv_class *bl;
2582 struct induction *v;
2584 rtx biv_final_value;
2587 rtx loop_start = loop->start;
2588 rtx loop_end = loop->end;
2590 for (bl = loop_iv_list; bl; bl = bl->next)
2592 /* Biv_total_increment must return a constant value,
2593 otherwise we can not calculate the split values. */
2595 increment = biv_total_increment (bl);
2596 if (! increment || GET_CODE (increment) != CONST_INT)
2599 /* The loop must be unrolled completely, or else have a known number
2600 of iterations and only one exit, or else the biv must be dead
2601 outside the loop, or else the final value must be known. Otherwise,
2602 it is unsafe to split the biv since it may not have the proper
2603 value on loop exit. */
2605 /* loop_number_exit_count is non-zero if the loop has an exit other than
2606 a fall through at the end. */
2609 biv_final_value = 0;
2610 if (unroll_type != UNROLL_COMPLETELY
2611 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2612 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2614 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2615 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2616 < INSN_LUID (bl->init_insn))
2617 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2618 && ! (biv_final_value = final_biv_value (loop, bl)))
2621 /* If any of the insns setting the BIV don't do so with a simple
2622 PLUS, we don't know how to split it. */
2623 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2624 if ((tem = single_set (v->insn)) == 0
2625 || GET_CODE (SET_DEST (tem)) != REG
2626 || REGNO (SET_DEST (tem)) != bl->regno
2627 || GET_CODE (SET_SRC (tem)) != PLUS)
2630 /* If final value is non-zero, then must emit an instruction which sets
2631 the value of the biv to the proper value. This is done after
2632 handling all of the givs, since some of them may need to use the
2633 biv's value in their initialization code. */
2635 /* This biv is splittable. If completely unrolling the loop, save
2636 the biv's initial value. Otherwise, save the constant zero. */
2638 if (biv_splittable == 1)
2640 if (unroll_type == UNROLL_COMPLETELY)
2642 /* If the initial value of the biv is itself (i.e. it is too
2643 complicated for strength_reduce to compute), or is a hard
2644 register, or it isn't invariant, then we must create a new
2645 pseudo reg to hold the initial value of the biv. */
2647 if (GET_CODE (bl->initial_value) == REG
2648 && (REGNO (bl->initial_value) == bl->regno
2649 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2650 || ! loop_invariant_p (loop, bl->initial_value)))
2652 rtx tem = gen_reg_rtx (bl->biv->mode);
2654 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2655 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2658 if (loop_dump_stream)
2659 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2660 bl->regno, REGNO (tem));
2662 splittable_regs[bl->regno] = tem;
2665 splittable_regs[bl->regno] = bl->initial_value;
2668 splittable_regs[bl->regno] = const0_rtx;
2670 /* Save the number of instructions that modify the biv, so that
2671 we can treat the last one specially. */
2673 splittable_regs_updates[bl->regno] = bl->biv_count;
2674 result += bl->biv_count;
2676 if (loop_dump_stream)
2677 fprintf (loop_dump_stream,
2678 "Biv %d safe to split.\n", bl->regno);
2681 /* Check every giv that depends on this biv to see whether it is
2682 splittable also. Even if the biv isn't splittable, givs which
2683 depend on it may be splittable if the biv is live outside the
2684 loop, and the givs aren't. */
2686 result += find_splittable_givs (loop, bl, unroll_type, increment,
2689 /* If final value is non-zero, then must emit an instruction which sets
2690 the value of the biv to the proper value. This is done after
2691 handling all of the givs, since some of them may need to use the
2692 biv's value in their initialization code. */
2693 if (biv_final_value)
2695 /* If the loop has multiple exits, emit the insns before the
2696 loop to ensure that it will always be executed no matter
2697 how the loop exits. Otherwise emit the insn after the loop,
2698 since this is slightly more efficient. */
2699 if (! loop->exit_count)
2700 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2705 /* Create a new register to hold the value of the biv, and then
2706 set the biv to its final value before the loop start. The biv
2707 is set to its final value before loop start to ensure that
2708 this insn will always be executed, no matter how the loop
2710 rtx tem = gen_reg_rtx (bl->biv->mode);
2711 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2713 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2715 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2719 if (loop_dump_stream)
2720 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2721 REGNO (bl->biv->src_reg), REGNO (tem));
2723 /* Set up the mapping from the original biv register to the new
2725 bl->biv->src_reg = tem;
2732 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2733 for the instruction that is using it. Do not make any changes to that
2737 verify_addresses (v, giv_inc, unroll_number)
2738 struct induction *v;
2743 rtx orig_addr = *v->location;
2744 rtx last_addr = plus_constant (v->dest_reg,
2745 INTVAL (giv_inc) * (unroll_number - 1));
2747 /* First check to see if either address would fail. Handle the fact
2748 that we have may have a match_dup. */
2749 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2750 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2753 /* Now put things back the way they were before. This should always
2755 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2761 /* For every giv based on the biv BL, check to determine whether it is
2762 splittable. This is a subroutine to find_splittable_regs ().
2764 Return the number of instructions that set splittable registers. */
2767 find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
2768 const struct loop *loop;
2769 struct iv_class *bl;
2770 enum unroll_types unroll_type;
2774 struct induction *v, *v2;
2779 /* Scan the list of givs, and set the same_insn field when there are
2780 multiple identical givs in the same insn. */
2781 for (v = bl->giv; v; v = v->next_iv)
2782 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2783 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2787 for (v = bl->giv; v; v = v->next_iv)
2791 /* Only split the giv if it has already been reduced, or if the loop is
2792 being completely unrolled. */
2793 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2796 /* The giv can be split if the insn that sets the giv is executed once
2797 and only once on every iteration of the loop. */
2798 /* An address giv can always be split. v->insn is just a use not a set,
2799 and hence it does not matter whether it is always executed. All that
2800 matters is that all the biv increments are always executed, and we
2801 won't reach here if they aren't. */
2802 if (v->giv_type != DEST_ADDR
2803 && (! v->always_computable
2804 || back_branch_in_range_p (loop, v->insn)))
2807 /* The giv increment value must be a constant. */
2808 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2810 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2813 /* The loop must be unrolled completely, or else have a known number of
2814 iterations and only one exit, or else the giv must be dead outside
2815 the loop, or else the final value of the giv must be known.
2816 Otherwise, it is not safe to split the giv since it may not have the
2817 proper value on loop exit. */
2819 /* The used outside loop test will fail for DEST_ADDR givs. They are
2820 never used outside the loop anyways, so it is always safe to split a
2824 if (unroll_type != UNROLL_COMPLETELY
2825 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2826 && v->giv_type != DEST_ADDR
2827 /* The next part is true if the pseudo is used outside the loop.
2828 We assume that this is true for any pseudo created after loop
2829 starts, because we don't have a reg_n_info entry for them. */
2830 && (REGNO (v->dest_reg) >= max_reg_before_loop
2831 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2832 /* Check for the case where the pseudo is set by a shift/add
2833 sequence, in which case the first insn setting the pseudo
2834 is the first insn of the shift/add sequence. */
2835 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2836 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2837 != INSN_UID (XEXP (tem, 0)))))
2838 /* Line above always fails if INSN was moved by loop opt. */
2839 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2840 >= INSN_LUID (loop->end)))
2841 /* Givs made from biv increments are missed by the above test, so
2842 test explicitly for them. */
2843 && (REGNO (v->dest_reg) < first_increment_giv
2844 || REGNO (v->dest_reg) > last_increment_giv)
2845 && ! (final_value = v->final_value))
2849 /* Currently, non-reduced/final-value givs are never split. */
2850 /* Should emit insns after the loop if possible, as the biv final value
2853 /* If the final value is non-zero, and the giv has not been reduced,
2854 then must emit an instruction to set the final value. */
2855 if (final_value && !v->new_reg)
2857 /* Create a new register to hold the value of the giv, and then set
2858 the giv to its final value before the loop start. The giv is set
2859 to its final value before loop start to ensure that this insn
2860 will always be executed, no matter how we exit. */
2861 tem = gen_reg_rtx (v->mode);
2862 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2863 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2866 if (loop_dump_stream)
2867 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2868 REGNO (v->dest_reg), REGNO (tem));
2874 /* This giv is splittable. If completely unrolling the loop, save the
2875 giv's initial value. Otherwise, save the constant zero for it. */
2877 if (unroll_type == UNROLL_COMPLETELY)
2879 /* It is not safe to use bl->initial_value here, because it may not
2880 be invariant. It is safe to use the initial value stored in
2881 the splittable_regs array if it is set. In rare cases, it won't
2882 be set, so then we do exactly the same thing as
2883 find_splittable_regs does to get a safe value. */
2884 rtx biv_initial_value;
2886 if (splittable_regs[bl->regno])
2887 biv_initial_value = splittable_regs[bl->regno];
2888 else if (GET_CODE (bl->initial_value) != REG
2889 || (REGNO (bl->initial_value) != bl->regno
2890 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2891 biv_initial_value = bl->initial_value;
2894 rtx tem = gen_reg_rtx (bl->biv->mode);
2896 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2897 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2899 biv_initial_value = tem;
2901 biv_initial_value = extend_value_for_giv (v, biv_initial_value);
2902 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2903 v->add_val, v->mode);
2910 /* If a giv was combined with another giv, then we can only split
2911 this giv if the giv it was combined with was reduced. This
2912 is because the value of v->new_reg is meaningless in this
2914 if (v->same && ! v->same->new_reg)
2916 if (loop_dump_stream)
2917 fprintf (loop_dump_stream,
2918 "giv combined with unreduced giv not split.\n");
2921 /* If the giv is an address destination, it could be something other
2922 than a simple register, these have to be treated differently. */
2923 else if (v->giv_type == DEST_REG)
2925 /* If value is not a constant, register, or register plus
2926 constant, then compute its value into a register before
2927 loop start. This prevents invalid rtx sharing, and should
2928 generate better code. We can use bl->initial_value here
2929 instead of splittable_regs[bl->regno] because this code
2930 is going before the loop start. */
2931 if (unroll_type == UNROLL_COMPLETELY
2932 && GET_CODE (value) != CONST_INT
2933 && GET_CODE (value) != REG
2934 && (GET_CODE (value) != PLUS
2935 || GET_CODE (XEXP (value, 0)) != REG
2936 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2938 rtx tem = gen_reg_rtx (v->mode);
2939 record_base_value (REGNO (tem), v->add_val, 0);
2940 emit_iv_add_mult (bl->initial_value, v->mult_val,
2941 v->add_val, tem, loop->start);
2945 splittable_regs[REGNO (v->new_reg)] = value;
2946 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2950 /* Splitting address givs is useful since it will often allow us
2951 to eliminate some increment insns for the base giv as
2954 /* If the addr giv is combined with a dest_reg giv, then all
2955 references to that dest reg will be remapped, which is NOT
2956 what we want for split addr regs. We always create a new
2957 register for the split addr giv, just to be safe. */
2959 /* If we have multiple identical address givs within a
2960 single instruction, then use a single pseudo reg for
2961 both. This is necessary in case one is a match_dup
2964 v->const_adjust = 0;
2968 v->dest_reg = v->same_insn->dest_reg;
2969 if (loop_dump_stream)
2970 fprintf (loop_dump_stream,
2971 "Sharing address givs in insn %d\n",
2972 INSN_UID (v->insn));
2974 /* If multiple address GIVs have been combined with the
2975 same dest_reg GIV, do not create a new register for
2977 else if (unroll_type != UNROLL_COMPLETELY
2978 && v->giv_type == DEST_ADDR
2979 && v->same && v->same->giv_type == DEST_ADDR
2980 && v->same->unrolled
2981 /* combine_givs_p may return true for some cases
2982 where the add and mult values are not equal.
2983 To share a register here, the values must be
2985 && rtx_equal_p (v->same->mult_val, v->mult_val)
2986 && rtx_equal_p (v->same->add_val, v->add_val)
2987 /* If the memory references have different modes,
2988 then the address may not be valid and we must
2989 not share registers. */
2990 && verify_addresses (v, giv_inc, unroll_number))
2992 v->dest_reg = v->same->dest_reg;
2995 else if (unroll_type != UNROLL_COMPLETELY)
2997 /* If not completely unrolling the loop, then create a new
2998 register to hold the split value of the DEST_ADDR giv.
2999 Emit insn to initialize its value before loop start. */
3001 rtx tem = gen_reg_rtx (v->mode);
3002 struct induction *same = v->same;
3003 rtx new_reg = v->new_reg;
3004 record_base_value (REGNO (tem), v->add_val, 0);
3006 if (same && same->derived_from)
3008 /* calculate_giv_inc doesn't work for derived givs.
3009 copy_loop_body works around the problem for the
3010 DEST_REG givs themselves, but it can't handle
3011 DEST_ADDR givs that have been combined with
3012 a derived DEST_REG giv.
3013 So Handle V as if the giv from which V->SAME has
3014 been derived has been combined with V.
3015 recombine_givs only derives givs from givs that
3016 are reduced the ordinary, so we need not worry
3017 about same->derived_from being in turn derived. */
3019 same = same->derived_from;
3020 new_reg = express_from (same, v);
3021 new_reg = replace_rtx (new_reg, same->dest_reg,
3025 /* If the address giv has a constant in its new_reg value,
3026 then this constant can be pulled out and put in value,
3027 instead of being part of the initialization code. */
3029 if (GET_CODE (new_reg) == PLUS
3030 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
3033 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
3035 /* Only succeed if this will give valid addresses.
3036 Try to validate both the first and the last
3037 address resulting from loop unrolling, if
3038 one fails, then can't do const elim here. */
3039 if (verify_addresses (v, giv_inc, unroll_number))
3041 /* Save the negative of the eliminated const, so
3042 that we can calculate the dest_reg's increment
3044 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
3046 new_reg = XEXP (new_reg, 0);
3047 if (loop_dump_stream)
3048 fprintf (loop_dump_stream,
3049 "Eliminating constant from giv %d\n",
3058 /* If the address hasn't been checked for validity yet, do so
3059 now, and fail completely if either the first or the last
3060 unrolled copy of the address is not a valid address
3061 for the instruction that uses it. */
3062 if (v->dest_reg == tem
3063 && ! verify_addresses (v, giv_inc, unroll_number))
3065 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3066 if (v2->same_insn == v)
3069 if (loop_dump_stream)
3070 fprintf (loop_dump_stream,
3071 "Invalid address for giv at insn %d\n",
3072 INSN_UID (v->insn));
3076 v->new_reg = new_reg;
3079 /* We set this after the address check, to guarantee that
3080 the register will be initialized. */
3083 /* To initialize the new register, just move the value of
3084 new_reg into it. This is not guaranteed to give a valid
3085 instruction on machines with complex addressing modes.
3086 If we can't recognize it, then delete it and emit insns
3087 to calculate the value from scratch. */
3088 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
3089 copy_rtx (v->new_reg)),
3091 if (recog_memoized (PREV_INSN (loop->start)) < 0)
3095 /* We can't use bl->initial_value to compute the initial
3096 value, because the loop may have been preconditioned.
3097 We must calculate it from NEW_REG. Try using
3098 force_operand instead of emit_iv_add_mult. */
3099 delete_insn (PREV_INSN (loop->start));
3102 ret = force_operand (v->new_reg, tem);
3104 emit_move_insn (tem, ret);
3105 sequence = gen_sequence ();
3107 emit_insn_before (sequence, loop->start);
3109 if (loop_dump_stream)
3110 fprintf (loop_dump_stream,
3111 "Invalid init insn, rewritten.\n");
3116 v->dest_reg = value;
3118 /* Check the resulting address for validity, and fail
3119 if the resulting address would be invalid. */
3120 if (! verify_addresses (v, giv_inc, unroll_number))
3122 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3123 if (v2->same_insn == v)
3126 if (loop_dump_stream)
3127 fprintf (loop_dump_stream,
3128 "Invalid address for giv at insn %d\n",
3129 INSN_UID (v->insn));
3132 if (v->same && v->same->derived_from)
3134 /* Handle V as if the giv from which V->SAME has
3135 been derived has been combined with V. */
3137 v->same = v->same->derived_from;
3138 v->new_reg = express_from (v->same, v);
3139 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3145 /* Store the value of dest_reg into the insn. This sharing
3146 will not be a problem as this insn will always be copied
3149 *v->location = v->dest_reg;
3151 /* If this address giv is combined with a dest reg giv, then
3152 save the base giv's induction pointer so that we will be
3153 able to handle this address giv properly. The base giv
3154 itself does not have to be splittable. */
3156 if (v->same && v->same->giv_type == DEST_REG)
3157 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3159 if (GET_CODE (v->new_reg) == REG)
3161 /* This giv maybe hasn't been combined with any others.
3162 Make sure that it's giv is marked as splittable here. */
3164 splittable_regs[REGNO (v->new_reg)] = value;
3165 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3167 /* Make it appear to depend upon itself, so that the
3168 giv will be properly split in the main loop above. */
3172 addr_combined_regs[REGNO (v->new_reg)] = v;
3176 if (loop_dump_stream)
3177 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3183 /* Currently, unreduced giv's can't be split. This is not too much
3184 of a problem since unreduced giv's are not live across loop
3185 iterations anyways. When unrolling a loop completely though,
3186 it makes sense to reduce&split givs when possible, as this will
3187 result in simpler instructions, and will not require that a reg
3188 be live across loop iterations. */
3190 splittable_regs[REGNO (v->dest_reg)] = value;
3191 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3192 REGNO (v->dest_reg), INSN_UID (v->insn));
3198 /* Unreduced givs are only updated once by definition. Reduced givs
3199 are updated as many times as their biv is. Mark it so if this is
3200 a splittable register. Don't need to do anything for address givs
3201 where this may not be a register. */
3203 if (GET_CODE (v->new_reg) == REG)
3207 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3209 if (count > 1 && v->derived_from)
3210 /* In this case, there is one set where the giv insn was and one
3211 set each after each biv increment. (Most are likely dead.) */
3214 splittable_regs_updates[REGNO (v->new_reg)] = count;
3219 if (loop_dump_stream)
3223 if (GET_CODE (v->dest_reg) == CONST_INT)
3225 else if (GET_CODE (v->dest_reg) != REG)
3226 regnum = REGNO (XEXP (v->dest_reg, 0));
3228 regnum = REGNO (v->dest_reg);
3229 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3230 regnum, INSN_UID (v->insn));
3237 /* Try to prove that the register is dead after the loop exits. Trace every
3238 loop exit looking for an insn that will always be executed, which sets
3239 the register to some value, and appears before the first use of the register
3240 is found. If successful, then return 1, otherwise return 0. */
3242 /* ?? Could be made more intelligent in the handling of jumps, so that
3243 it can search past if statements and other similar structures. */
3246 reg_dead_after_loop (loop, reg)
3247 const struct loop *loop;
3253 int label_count = 0;
3255 /* In addition to checking all exits of this loop, we must also check
3256 all exits of inner nested loops that would exit this loop. We don't
3257 have any way to identify those, so we just give up if there are any
3258 such inner loop exits. */
3260 for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
3263 if (label_count != loop->exit_count)
3266 /* HACK: Must also search the loop fall through exit, create a label_ref
3267 here which points to the loop->end, and append the loop_number_exit_labels
3269 label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
3270 LABEL_NEXTREF (label) = loop->exit_labels;
3272 for ( ; label; label = LABEL_NEXTREF (label))
3274 /* Succeed if find an insn which sets the biv or if reach end of
3275 function. Fail if find an insn that uses the biv, or if come to
3276 a conditional jump. */
3278 insn = NEXT_INSN (XEXP (label, 0));
3281 code = GET_CODE (insn);
3282 if (GET_RTX_CLASS (code) == 'i')
3286 if (reg_referenced_p (reg, PATTERN (insn)))
3289 set = single_set (insn);
3290 if (set && rtx_equal_p (SET_DEST (set), reg))
3294 if (code == JUMP_INSN)
3296 if (GET_CODE (PATTERN (insn)) == RETURN)
3298 else if (!any_uncondjump_p (insn)
3299 /* Prevent infinite loop following infinite loops. */
3300 || jump_count++ > 20)
3303 insn = JUMP_LABEL (insn);
3306 insn = NEXT_INSN (insn);
3310 /* Success, the register is dead on all loop exits. */
3314 /* Try to calculate the final value of the biv, the value it will have at
3315 the end of the loop. If we can do it, return that value. */
3318 final_biv_value (loop, bl)
3319 const struct loop *loop;
3320 struct iv_class *bl;
3322 rtx loop_end = loop->end;
3323 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3326 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3328 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3331 /* The final value for reversed bivs must be calculated differently than
3332 for ordinary bivs. In this case, there is already an insn after the
3333 loop which sets this biv's final value (if necessary), and there are
3334 no other loop exits, so we can return any value. */
3337 if (loop_dump_stream)
3338 fprintf (loop_dump_stream,
3339 "Final biv value for %d, reversed biv.\n", bl->regno);
3344 /* Try to calculate the final value as initial value + (number of iterations
3345 * increment). For this to work, increment must be invariant, the only
3346 exit from the loop must be the fall through at the bottom (otherwise
3347 it may not have its final value when the loop exits), and the initial
3348 value of the biv must be invariant. */
3350 if (n_iterations != 0
3351 && ! loop->exit_count
3352 && loop_invariant_p (loop, bl->initial_value))
3354 increment = biv_total_increment (bl);
3356 if (increment && loop_invariant_p (loop, increment))
3358 /* Can calculate the loop exit value, emit insns after loop
3359 end to calculate this value into a temporary register in
3360 case it is needed later. */
3362 tem = gen_reg_rtx (bl->biv->mode);
3363 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3364 /* Make sure loop_end is not the last insn. */
3365 if (NEXT_INSN (loop_end) == 0)
3366 emit_note_after (NOTE_INSN_DELETED, loop_end);
3367 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3368 bl->initial_value, tem, NEXT_INSN (loop_end));
3370 if (loop_dump_stream)
3371 fprintf (loop_dump_stream,
3372 "Final biv value for %d, calculated.\n", bl->regno);
3378 /* Check to see if the biv is dead at all loop exits. */
3379 if (reg_dead_after_loop (loop, bl->biv->src_reg))
3381 if (loop_dump_stream)
3382 fprintf (loop_dump_stream,
3383 "Final biv value for %d, biv dead after loop exit.\n",
3392 /* Try to calculate the final value of the giv, the value it will have at
3393 the end of the loop. If we can do it, return that value. */
3396 final_giv_value (loop, v)
3397 const struct loop *loop;
3398 struct induction *v;
3400 struct iv_class *bl;
3403 rtx insert_before, seq;
3404 rtx loop_end = loop->end;
3405 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3407 bl = reg_biv_class[REGNO (v->src_reg)];
3409 /* The final value for givs which depend on reversed bivs must be calculated
3410 differently than for ordinary givs. In this case, there is already an
3411 insn after the loop which sets this giv's final value (if necessary),
3412 and there are no other loop exits, so we can return any value. */
3415 if (loop_dump_stream)
3416 fprintf (loop_dump_stream,
3417 "Final giv value for %d, depends on reversed biv\n",
3418 REGNO (v->dest_reg));
3422 /* Try to calculate the final value as a function of the biv it depends
3423 upon. The only exit from the loop must be the fall through at the bottom
3424 (otherwise it may not have its final value when the loop exits). */
3426 /* ??? Can calculate the final giv value by subtracting off the
3427 extra biv increments times the giv's mult_val. The loop must have
3428 only one exit for this to work, but the loop iterations does not need
3431 if (n_iterations != 0
3432 && ! loop->exit_count)
3434 /* ?? It is tempting to use the biv's value here since these insns will
3435 be put after the loop, and hence the biv will have its final value
3436 then. However, this fails if the biv is subsequently eliminated.
3437 Perhaps determine whether biv's are eliminable before trying to
3438 determine whether giv's are replaceable so that we can use the
3439 biv value here if it is not eliminable. */
3441 /* We are emitting code after the end of the loop, so we must make
3442 sure that bl->initial_value is still valid then. It will still
3443 be valid if it is invariant. */
3445 increment = biv_total_increment (bl);
3447 if (increment && loop_invariant_p (loop, increment)
3448 && loop_invariant_p (loop, bl->initial_value))
3450 /* Can calculate the loop exit value of its biv as
3451 (n_iterations * increment) + initial_value */
3453 /* The loop exit value of the giv is then
3454 (final_biv_value - extra increments) * mult_val + add_val.
3455 The extra increments are any increments to the biv which
3456 occur in the loop after the giv's value is calculated.
3457 We must search from the insn that sets the giv to the end
3458 of the loop to calculate this value. */
3460 insert_before = NEXT_INSN (loop_end);
3462 /* Put the final biv value in tem. */
3463 tem = gen_reg_rtx (v->mode);
3464 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3465 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3466 extend_value_for_giv (v, bl->initial_value),
3467 tem, insert_before);
3469 /* Subtract off extra increments as we find them. */
3470 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3471 insn = NEXT_INSN (insn))
3473 struct induction *biv;
3475 for (biv = bl->biv; biv; biv = biv->next_iv)
3476 if (biv->insn == insn)
3479 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3480 biv->add_val, NULL_RTX, 0,
3482 seq = gen_sequence ();
3484 emit_insn_before (seq, insert_before);
3488 /* Now calculate the giv's final value. */
3489 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3492 if (loop_dump_stream)
3493 fprintf (loop_dump_stream,
3494 "Final giv value for %d, calc from biv's value.\n",
3495 REGNO (v->dest_reg));
3501 /* Replaceable giv's should never reach here. */
3505 /* Check to see if the biv is dead at all loop exits. */
3506 if (reg_dead_after_loop (loop, v->dest_reg))
3508 if (loop_dump_stream)
3509 fprintf (loop_dump_stream,
3510 "Final giv value for %d, giv dead after loop exit.\n",
3511 REGNO (v->dest_reg));
3520 /* Look back before LOOP->START for then insn that sets REG and return
3521 the equivalent constant if there is a REG_EQUAL note otherwise just
3522 the SET_SRC of REG. */
3525 loop_find_equiv_value (loop, reg)
3526 const struct loop *loop;
3529 rtx loop_start = loop->start;
3534 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3536 if (GET_CODE (insn) == CODE_LABEL)
3539 else if (INSN_P (insn) && reg_set_p (reg, insn))
3541 /* We found the last insn before the loop that sets the register.
3542 If it sets the entire register, and has a REG_EQUAL note,
3543 then use the value of the REG_EQUAL note. */
3544 if ((set = single_set (insn))
3545 && (SET_DEST (set) == reg))
3547 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3549 /* Only use the REG_EQUAL note if it is a constant.
3550 Other things, divide in particular, will cause
3551 problems later if we use them. */
3552 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3553 && CONSTANT_P (XEXP (note, 0)))
3554 ret = XEXP (note, 0);
3556 ret = SET_SRC (set);
3558 /* We cannot do this if it changes between the
3559 assignment and loop start though. */
3560 if (modified_between_p (ret, insn, loop_start))
3569 /* Return a simplified rtx for the expression OP - REG.
3571 REG must appear in OP, and OP must be a register or the sum of a register
3574 Thus, the return value must be const0_rtx or the second term.
3576 The caller is responsible for verifying that REG appears in OP and OP has
3580 subtract_reg_term (op, reg)
3585 if (GET_CODE (op) == PLUS)
3587 if (XEXP (op, 0) == reg)
3588 return XEXP (op, 1);
3589 else if (XEXP (op, 1) == reg)
3590 return XEXP (op, 0);
3592 /* OP does not contain REG as a term. */
3597 /* Find and return register term common to both expressions OP0 and
3598 OP1 or NULL_RTX if no such term exists. Each expression must be a
3599 REG or a PLUS of a REG. */
3602 find_common_reg_term (op0, op1)
3605 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3606 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3613 if (GET_CODE (op0) == PLUS)
3614 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3616 op01 = const0_rtx, op00 = op0;
3618 if (GET_CODE (op1) == PLUS)
3619 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3621 op11 = const0_rtx, op10 = op1;
3623 /* Find and return common register term if present. */
3624 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3626 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3630 /* No common register term found. */
3634 /* Calculate the number of loop iterations. Returns the exact number of loop
3635 iterations if it can be calculated, otherwise returns zero. */
3637 unsigned HOST_WIDE_INT
3638 loop_iterations (loop)
3641 rtx comparison, comparison_value;
3642 rtx iteration_var, initial_value, increment, final_value;
3643 enum rtx_code comparison_code;
3644 HOST_WIDE_INT abs_inc;
3645 unsigned HOST_WIDE_INT abs_diff;
3648 int unsigned_p, compare_dir, final_larger;
3651 struct loop_info *loop_info = LOOP_INFO (loop);
3653 loop_info->n_iterations = 0;
3654 loop_info->initial_value = 0;
3655 loop_info->initial_equiv_value = 0;
3656 loop_info->comparison_value = 0;
3657 loop_info->final_value = 0;
3658 loop_info->final_equiv_value = 0;
3659 loop_info->increment = 0;
3660 loop_info->iteration_var = 0;
3661 loop_info->unroll_number = 1;
3663 /* We used to use prev_nonnote_insn here, but that fails because it might
3664 accidentally get the branch for a contained loop if the branch for this
3665 loop was deleted. We can only trust branches immediately before the
3667 last_loop_insn = PREV_INSN (loop->end);
3669 /* ??? We should probably try harder to find the jump insn
3670 at the end of the loop. The following code assumes that
3671 the last loop insn is a jump to the top of the loop. */
3672 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3674 if (loop_dump_stream)
3675 fprintf (loop_dump_stream,
3676 "Loop iterations: No final conditional branch found.\n");
3680 /* If there is a more than a single jump to the top of the loop
3681 we cannot (easily) determine the iteration count. */
3682 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3684 if (loop_dump_stream)
3685 fprintf (loop_dump_stream,
3686 "Loop iterations: Loop has multiple back edges.\n");
3690 /* Find the iteration variable. If the last insn is a conditional
3691 branch, and the insn before tests a register value, make that the
3692 iteration variable. */
3694 comparison = get_condition_for_loop (loop, last_loop_insn);
3695 if (comparison == 0)
3697 if (loop_dump_stream)
3698 fprintf (loop_dump_stream,
3699 "Loop iterations: No final comparison found.\n");
3703 /* ??? Get_condition may switch position of induction variable and
3704 invariant register when it canonicalizes the comparison. */
3706 comparison_code = GET_CODE (comparison);
3707 iteration_var = XEXP (comparison, 0);
3708 comparison_value = XEXP (comparison, 1);
3710 if (GET_CODE (iteration_var) != REG)
3712 if (loop_dump_stream)
3713 fprintf (loop_dump_stream,
3714 "Loop iterations: Comparison not against register.\n");
3718 /* The only new registers that are created before loop iterations
3719 are givs made from biv increments or registers created by
3720 load_mems. In the latter case, it is possible that try_copy_prop
3721 will propagate a new pseudo into the old iteration register but
3722 this will be marked by having the REG_USERVAR_P bit set. */
3724 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements
3725 && ! REG_USERVAR_P (iteration_var))
3728 iteration_info (loop, iteration_var, &initial_value, &increment);
3730 if (initial_value == 0)
3731 /* iteration_info already printed a message. */
3736 switch (comparison_code)
3751 /* Cannot determine loop iterations with this case. */
3770 /* If the comparison value is an invariant register, then try to find
3771 its value from the insns before the start of the loop. */
3773 final_value = comparison_value;
3774 if (GET_CODE (comparison_value) == REG
3775 && loop_invariant_p (loop, comparison_value))
3777 final_value = loop_find_equiv_value (loop, comparison_value);
3779 /* If we don't get an invariant final value, we are better
3780 off with the original register. */
3781 if (! loop_invariant_p (loop, final_value))
3782 final_value = comparison_value;
3785 /* Calculate the approximate final value of the induction variable
3786 (on the last successful iteration). The exact final value
3787 depends on the branch operator, and increment sign. It will be
3788 wrong if the iteration variable is not incremented by one each
3789 time through the loop and (comparison_value + off_by_one -
3790 initial_value) % increment != 0.
3791 ??? Note that the final_value may overflow and thus final_larger
3792 will be bogus. A potentially infinite loop will be classified
3793 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3795 final_value = plus_constant (final_value, off_by_one);
3797 /* Save the calculated values describing this loop's bounds, in case
3798 precondition_loop_p will need them later. These values can not be
3799 recalculated inside precondition_loop_p because strength reduction
3800 optimizations may obscure the loop's structure.
3802 These values are only required by precondition_loop_p and insert_bct
3803 whenever the number of iterations cannot be computed at compile time.
3804 Only the difference between final_value and initial_value is
3805 important. Note that final_value is only approximate. */
3806 loop_info->initial_value = initial_value;
3807 loop_info->comparison_value = comparison_value;
3808 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3809 loop_info->increment = increment;
3810 loop_info->iteration_var = iteration_var;
3811 loop_info->comparison_code = comparison_code;
3813 /* Try to determine the iteration count for loops such
3814 as (for i = init; i < init + const; i++). When running the
3815 loop optimization twice, the first pass often converts simple
3816 loops into this form. */
3818 if (REG_P (initial_value))
3824 reg1 = initial_value;
3825 if (GET_CODE (final_value) == PLUS)
3826 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3828 reg2 = final_value, const2 = const0_rtx;
3830 /* Check for initial_value = reg1, final_value = reg2 + const2,
3831 where reg1 != reg2. */
3832 if (REG_P (reg2) && reg2 != reg1)
3836 /* Find what reg1 is equivalent to. Hopefully it will
3837 either be reg2 or reg2 plus a constant. */
3838 temp = loop_find_equiv_value (loop, reg1);
3840 if (find_common_reg_term (temp, reg2))
3841 initial_value = temp;
3844 /* Find what reg2 is equivalent to. Hopefully it will
3845 either be reg1 or reg1 plus a constant. Let's ignore
3846 the latter case for now since it is not so common. */
3847 temp = loop_find_equiv_value (loop, reg2);
3849 if (temp == loop_info->iteration_var)
3850 temp = initial_value;
3852 final_value = (const2 == const0_rtx)
3853 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3856 else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
3860 /* When running the loop optimizer twice, check_dbra_loop
3861 further obfuscates reversible loops of the form:
3862 for (i = init; i < init + const; i++). We often end up with
3863 final_value = 0, initial_value = temp, temp = temp2 - init,
3864 where temp2 = init + const. If the loop has a vtop we
3865 can replace initial_value with const. */
3867 temp = loop_find_equiv_value (loop, reg1);
3869 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3871 rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
3873 if (GET_CODE (temp2) == PLUS
3874 && XEXP (temp2, 0) == XEXP (temp, 1))
3875 initial_value = XEXP (temp2, 1);
3880 /* If have initial_value = reg + const1 and final_value = reg +
3881 const2, then replace initial_value with const1 and final_value
3882 with const2. This should be safe since we are protected by the
3883 initial comparison before entering the loop if we have a vtop.
3884 For example, a + b < a + c is not equivalent to b < c for all a
3885 when using modulo arithmetic.
3887 ??? Without a vtop we could still perform the optimization if we check
3888 the initial and final values carefully. */
3890 && (reg_term = find_common_reg_term (initial_value, final_value)))
3892 initial_value = subtract_reg_term (initial_value, reg_term);
3893 final_value = subtract_reg_term (final_value, reg_term);
3896 loop_info->initial_equiv_value = initial_value;
3897 loop_info->final_equiv_value = final_value;
3899 /* For EQ comparison loops, we don't have a valid final value.
3900 Check this now so that we won't leave an invalid value if we
3901 return early for any other reason. */
3902 if (comparison_code == EQ)
3903 loop_info->final_equiv_value = loop_info->final_value = 0;
3907 if (loop_dump_stream)
3908 fprintf (loop_dump_stream,
3909 "Loop iterations: Increment value can't be calculated.\n");
3913 if (GET_CODE (increment) != CONST_INT)
3915 /* If we have a REG, check to see if REG holds a constant value. */
3916 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3917 clear if it is worthwhile to try to handle such RTL. */
3918 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3919 increment = loop_find_equiv_value (loop, increment);
3921 if (GET_CODE (increment) != CONST_INT)
3923 if (loop_dump_stream)
3925 fprintf (loop_dump_stream,
3926 "Loop iterations: Increment value not constant ");
3927 print_rtl (loop_dump_stream, increment);
3928 fprintf (loop_dump_stream, ".\n");
3932 loop_info->increment = increment;
3935 if (GET_CODE (initial_value) != CONST_INT)
3937 if (loop_dump_stream)
3939 fprintf (loop_dump_stream,
3940 "Loop iterations: Initial value not constant ");
3941 print_rtl (loop_dump_stream, initial_value);
3942 fprintf (loop_dump_stream, ".\n");
3946 else if (comparison_code == EQ)
3948 if (loop_dump_stream)
3949 fprintf (loop_dump_stream,
3950 "Loop iterations: EQ comparison loop.\n");
3953 else if (GET_CODE (final_value) != CONST_INT)
3955 if (loop_dump_stream)
3957 fprintf (loop_dump_stream,
3958 "Loop iterations: Final value not constant ");
3959 print_rtl (loop_dump_stream, final_value);
3960 fprintf (loop_dump_stream, ".\n");
3965 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3968 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3969 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3970 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3971 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3973 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3974 - (INTVAL (final_value) < INTVAL (initial_value));
3976 if (INTVAL (increment) > 0)
3978 else if (INTVAL (increment) == 0)
3983 /* There are 27 different cases: compare_dir = -1, 0, 1;
3984 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3985 There are 4 normal cases, 4 reverse cases (where the iteration variable
3986 will overflow before the loop exits), 4 infinite loop cases, and 15
3987 immediate exit (0 or 1 iteration depending on loop type) cases.
3988 Only try to optimize the normal cases. */
3990 /* (compare_dir/final_larger/increment_dir)
3991 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3992 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3993 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3994 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3996 /* ?? If the meaning of reverse loops (where the iteration variable
3997 will overflow before the loop exits) is undefined, then could
3998 eliminate all of these special checks, and just always assume
3999 the loops are normal/immediate/infinite. Note that this means
4000 the sign of increment_dir does not have to be known. Also,
4001 since it does not really hurt if immediate exit loops or infinite loops
4002 are optimized, then that case could be ignored also, and hence all
4003 loops can be optimized.
4005 According to ANSI Spec, the reverse loop case result is undefined,
4006 because the action on overflow is undefined.
4008 See also the special test for NE loops below. */
4010 if (final_larger == increment_dir && final_larger != 0
4011 && (final_larger == compare_dir || compare_dir == 0))
4016 if (loop_dump_stream)
4017 fprintf (loop_dump_stream,
4018 "Loop iterations: Not normal loop.\n");
4022 /* Calculate the number of iterations, final_value is only an approximation,
4023 so correct for that. Note that abs_diff and n_iterations are
4024 unsigned, because they can be as large as 2^n - 1. */
4026 abs_inc = INTVAL (increment);
4028 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
4029 else if (abs_inc < 0)
4031 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
4037 /* For NE tests, make sure that the iteration variable won't miss
4038 the final value. If abs_diff mod abs_incr is not zero, then the
4039 iteration variable will overflow before the loop exits, and we
4040 can not calculate the number of iterations. */
4041 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4044 /* Note that the number of iterations could be calculated using
4045 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4046 handle potential overflow of the summation. */
4047 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4048 return loop_info->n_iterations;
4052 /* Replace uses of split bivs with their split pseudo register. This is
4053 for original instructions which remain after loop unrolling without
4057 remap_split_bivs (x)
4060 register enum rtx_code code;
4062 register const char *fmt;
4067 code = GET_CODE (x);
4082 /* If non-reduced/final-value givs were split, then this would also
4083 have to remap those givs also. */
4085 if (REGNO (x) < max_reg_before_loop
4086 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
4087 return reg_biv_class[REGNO (x)]->biv->src_reg;
4094 fmt = GET_RTX_FORMAT (code);
4095 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4098 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
4099 else if (fmt[i] == 'E')
4102 for (j = 0; j < XVECLEN (x, i); j++)
4103 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
4109 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4110 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4111 return 0. COPY_START is where we can start looking for the insns
4112 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4115 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4116 must dominate LAST_UID.
4118 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4119 may not dominate LAST_UID.
4121 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4122 must dominate LAST_UID. */
4125 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4132 int passed_jump = 0;
4133 rtx p = NEXT_INSN (copy_start);
4135 while (INSN_UID (p) != first_uid)
4137 if (GET_CODE (p) == JUMP_INSN)
4139 /* Could not find FIRST_UID. */
4145 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4146 if (! INSN_P (p) || ! dead_or_set_regno_p (p, regno))
4149 /* FIRST_UID is always executed. */
4150 if (passed_jump == 0)
4153 while (INSN_UID (p) != last_uid)
4155 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4156 can not be sure that FIRST_UID dominates LAST_UID. */
4157 if (GET_CODE (p) == CODE_LABEL)
4159 /* Could not find LAST_UID, but we reached the end of the loop, so
4161 else if (p == copy_end)
4166 /* FIRST_UID is always executed if LAST_UID is executed. */
4170 /* This routine is called when the number of iterations for the unrolled
4171 loop is one. The goal is to identify a loop that begins with an
4172 unconditional branch to the loop continuation note (or a label just after).
4173 In this case, the unconditional branch that starts the loop needs to be
4174 deleted so that we execute the single iteration. */
4176 ujump_to_loop_cont (loop_start, loop_cont)
4180 rtx x, label, label_ref;
4182 /* See if loop start, or the next insn is an unconditional jump. */
4183 loop_start = next_nonnote_insn (loop_start);
4185 x = pc_set (loop_start);
4189 label_ref = SET_SRC (x);
4193 /* Examine insn after loop continuation note. Return if not a label. */
4194 label = next_nonnote_insn (loop_cont);
4195 if (label == 0 || GET_CODE (label) != CODE_LABEL)
4198 /* Return the loop start if the branch label matches the code label. */
4199 if (CODE_LABEL_NUMBER (label) == CODE_LABEL_NUMBER (XEXP (label_ref,0)))