1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 93, 94, 95, 97, 98, 1999 Free Software Foundation, Inc.
3 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* Try to unroll a loop, and split induction variables.
24 Loops for which the number of iterations can be calculated exactly are
25 handled specially. If the number of iterations times the insn_count is
26 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
27 Otherwise, we try to unroll the loop a number of times modulo the number
28 of iterations, so that only one exit test will be needed. It is unrolled
29 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
32 Otherwise, if the number of iterations can be calculated exactly at
33 run time, and the loop is always entered at the top, then we try to
34 precondition the loop. That is, at run time, calculate how many times
35 the loop will execute, and then execute the loop body a few times so
36 that the remaining iterations will be some multiple of 4 (or 2 if the
37 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
38 with only one exit test needed at the end of the loop.
40 Otherwise, if the number of iterations can not be calculated exactly,
41 not even at run time, then we still unroll the loop a number of times
42 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
43 but there must be an exit test after each copy of the loop body.
45 For each induction variable, which is dead outside the loop (replaceable)
46 or for which we can easily calculate the final value, if we can easily
47 calculate its value at each place where it is set as a function of the
48 current loop unroll count and the variable's value at loop entry, then
49 the induction variable is split into `N' different variables, one for
50 each copy of the loop body. One variable is live across the backward
51 branch, and the others are all calculated as a function of this variable.
52 This helps eliminate data dependencies, and leads to further opportunities
55 /* Possible improvements follow: */
57 /* ??? Add an extra pass somewhere to determine whether unrolling will
58 give any benefit. E.g. after generating all unrolled insns, compute the
59 cost of all insns and compare against cost of insns in rolled loop.
61 - On traditional architectures, unrolling a non-constant bound loop
62 is a win if there is a giv whose only use is in memory addresses, the
63 memory addresses can be split, and hence giv increments can be
65 - It is also a win if the loop is executed many times, and preconditioning
66 can be performed for the loop.
67 Add code to check for these and similar cases. */
69 /* ??? Improve control of which loops get unrolled. Could use profiling
70 info to only unroll the most commonly executed loops. Perhaps have
71 a user specifyable option to control the amount of code expansion,
72 or the percent of loops to consider for unrolling. Etc. */
74 /* ??? Look at the register copies inside the loop to see if they form a
75 simple permutation. If so, iterate the permutation until it gets back to
76 the start state. This is how many times we should unroll the loop, for
77 best results, because then all register copies can be eliminated.
78 For example, the lisp nreverse function should be unrolled 3 times
87 ??? The number of times to unroll the loop may also be based on data
88 references in the loop. For example, if we have a loop that references
89 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
91 /* ??? Add some simple linear equation solving capability so that we can
92 determine the number of loop iterations for more complex loops.
93 For example, consider this loop from gdb
94 #define SWAP_TARGET_AND_HOST(buffer,len)
97 char *p = (char *) buffer;
98 char *q = ((char *) buffer) + len - 1;
99 int iterations = (len + 1) >> 1;
101 for (p; p < q; p++, q--;)
109 start value = p = &buffer + current_iteration
110 end value = q = &buffer + len - 1 - current_iteration
111 Given the loop exit test of "p < q", then there must be "q - p" iterations,
112 set equal to zero and solve for number of iterations:
113 q - p = len - 1 - 2*current_iteration = 0
114 current_iteration = (len - 1) / 2
115 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
116 iterations of this loop. */
118 /* ??? Currently, no labels are marked as loop invariant when doing loop
119 unrolling. This is because an insn inside the loop, that loads the address
120 of a label inside the loop into a register, could be moved outside the loop
121 by the invariant code motion pass if labels were invariant. If the loop
122 is subsequently unrolled, the code will be wrong because each unrolled
123 body of the loop will use the same address, whereas each actually needs a
124 different address. A case where this happens is when a loop containing
125 a switch statement is unrolled.
127 It would be better to let labels be considered invariant. When we
128 unroll loops here, check to see if any insns using a label local to the
129 loop were moved before the loop. If so, then correct the problem, by
130 moving the insn back into the loop, or perhaps replicate the insn before
131 the loop, one copy for each time the loop is unrolled. */
133 /* The prime factors looked for when trying to unroll a loop by some
134 number which is modulo the total number of iterations. Just checking
135 for these 4 prime factors will find at least one factor for 75% of
136 all numbers theoretically. Practically speaking, this will succeed
137 almost all of the time since loops are generally a multiple of 2
140 #define NUM_FACTORS 4
142 struct _factor { int factor, count; } factors[NUM_FACTORS]
143 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
145 /* Describes the different types of loop unrolling performed. */
147 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
153 #include "insn-config.h"
154 #include "integrate.h"
158 #include "function.h"
163 /* This controls which loops are unrolled, and by how much we unroll
166 #ifndef MAX_UNROLLED_INSNS
167 #define MAX_UNROLLED_INSNS 100
170 /* Indexed by register number, if non-zero, then it contains a pointer
171 to a struct induction for a DEST_REG giv which has been combined with
172 one of more address givs. This is needed because whenever such a DEST_REG
173 giv is modified, we must modify the value of all split address givs
174 that were combined with this DEST_REG giv. */
176 static struct induction **addr_combined_regs;
178 /* Indexed by register number, if this is a splittable induction variable,
179 then this will hold the current value of the register, which depends on the
182 static rtx *splittable_regs;
184 /* Indexed by register number, if this is a splittable induction variable,
185 this indicates if it was made from a derived giv. */
186 static char *derived_regs;
188 /* Indexed by register number, if this is a splittable induction variable,
189 then this will hold the number of instructions in the loop that modify
190 the induction variable. Used to ensure that only the last insn modifying
191 a split iv will update the original iv of the dest. */
193 static int *splittable_regs_updates;
195 /* Forward declarations. */
197 static void init_reg_map PROTO((struct inline_remap *, int));
198 static rtx calculate_giv_inc PROTO((rtx, rtx, int));
199 static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
200 static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
201 static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
202 enum unroll_types, rtx, rtx, rtx, rtx));
203 static void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
204 static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int,
205 unsigned HOST_WIDE_INT));
206 static int find_splittable_givs PROTO((struct iv_class *, enum unroll_types,
207 rtx, rtx, rtx, int));
208 static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
209 static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
210 static int verify_addresses PROTO((struct induction *, rtx, int));
211 static rtx remap_split_bivs PROTO((rtx));
212 static rtx find_common_reg_term PROTO((rtx, rtx));
213 static rtx subtract_reg_term PROTO((rtx, rtx));
214 static rtx loop_find_equiv_value PROTO((rtx, rtx));
216 /* Try to unroll one loop and split induction variables in the loop.
218 The loop is described by the arguments LOOP_END, INSN_COUNT, and
219 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
220 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
221 indicates whether information generated in the strength reduction pass
224 This function is intended to be called from within `strength_reduce'
228 unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
229 loop_info, strength_reduce_p)
233 rtx end_insert_before;
234 struct loop_info *loop_info;
235 int strength_reduce_p;
238 int unroll_number = 1;
239 rtx copy_start, copy_end;
240 rtx insn, sequence, pattern, tem;
241 int max_labelno, max_insnno;
243 struct inline_remap *map;
244 char *local_label = NULL;
246 int max_local_regnum;
251 int splitting_not_safe = 0;
252 enum unroll_types unroll_type;
253 int loop_preconditioned = 0;
255 /* This points to the last real insn in the loop, which should be either
256 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
260 /* Don't bother unrolling huge loops. Since the minimum factor is
261 two, loops greater than one half of MAX_UNROLLED_INSNS will never
263 if (insn_count > MAX_UNROLLED_INSNS / 2)
265 if (loop_dump_stream)
266 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
270 /* When emitting debugger info, we can't unroll loops with unequal numbers
271 of block_beg and block_end notes, because that would unbalance the block
272 structure of the function. This can happen as a result of the
273 "if (foo) bar; else break;" optimization in jump.c. */
274 /* ??? Gcc has a general policy that -g is never supposed to change the code
275 that the compiler emits, so we must disable this optimization always,
276 even if debug info is not being output. This is rare, so this should
277 not be a significant performance problem. */
279 if (1 /* write_symbols != NO_DEBUG */)
281 int block_begins = 0;
284 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
286 if (GET_CODE (insn) == NOTE)
288 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
290 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
295 if (block_begins != block_ends)
297 if (loop_dump_stream)
298 fprintf (loop_dump_stream,
299 "Unrolling failure: Unbalanced block notes.\n");
304 /* Determine type of unroll to perform. Depends on the number of iterations
305 and the size of the loop. */
307 /* If there is no strength reduce info, then set
308 loop_info->n_iterations to zero. This can happen if
309 strength_reduce can't find any bivs in the loop. A value of zero
310 indicates that the number of iterations could not be calculated. */
312 if (! strength_reduce_p)
313 loop_info->n_iterations = 0;
315 if (loop_dump_stream && loop_info->n_iterations > 0)
317 fputs ("Loop unrolling: ", loop_dump_stream);
318 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
319 loop_info->n_iterations);
320 fputs (" iterations.\n", loop_dump_stream);
323 /* Find and save a pointer to the last nonnote insn in the loop. */
325 last_loop_insn = prev_nonnote_insn (loop_end);
327 /* Calculate how many times to unroll the loop. Indicate whether or
328 not the loop is being completely unrolled. */
330 if (loop_info->n_iterations == 1)
332 /* If number of iterations is exactly 1, then eliminate the compare and
333 branch at the end of the loop since they will never be taken.
334 Then return, since no other action is needed here. */
336 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
337 don't do anything. */
339 if (GET_CODE (last_loop_insn) == BARRIER)
341 /* Delete the jump insn. This will delete the barrier also. */
342 delete_insn (PREV_INSN (last_loop_insn));
344 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
347 rtx prev = PREV_INSN (last_loop_insn);
349 delete_insn (last_loop_insn);
351 /* The immediately preceding insn may be a compare which must be
353 if (sets_cc0_p (prev))
359 else if (loop_info->n_iterations > 0
360 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
362 unroll_number = loop_info->n_iterations;
363 unroll_type = UNROLL_COMPLETELY;
365 else if (loop_info->n_iterations > 0)
367 /* Try to factor the number of iterations. Don't bother with the
368 general case, only using 2, 3, 5, and 7 will get 75% of all
369 numbers theoretically, and almost all in practice. */
371 for (i = 0; i < NUM_FACTORS; i++)
372 factors[i].count = 0;
374 temp = loop_info->n_iterations;
375 for (i = NUM_FACTORS - 1; i >= 0; i--)
376 while (temp % factors[i].factor == 0)
379 temp = temp / factors[i].factor;
382 /* Start with the larger factors first so that we generally
383 get lots of unrolling. */
387 for (i = 3; i >= 0; i--)
388 while (factors[i].count--)
390 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
392 unroll_number *= factors[i].factor;
393 temp *= factors[i].factor;
399 /* If we couldn't find any factors, then unroll as in the normal
401 if (unroll_number == 1)
403 if (loop_dump_stream)
404 fprintf (loop_dump_stream,
405 "Loop unrolling: No factors found.\n");
408 unroll_type = UNROLL_MODULO;
412 /* Default case, calculate number of times to unroll loop based on its
414 if (unroll_number == 1)
416 if (8 * insn_count < MAX_UNROLLED_INSNS)
418 else if (4 * insn_count < MAX_UNROLLED_INSNS)
423 unroll_type = UNROLL_NAIVE;
426 /* Now we know how many times to unroll the loop. */
428 if (loop_dump_stream)
429 fprintf (loop_dump_stream,
430 "Unrolling loop %d times.\n", unroll_number);
433 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
435 /* Loops of these types can start with jump down to the exit condition
436 in rare circumstances.
438 Consider a pair of nested loops where the inner loop is part
439 of the exit code for the outer loop.
441 In this case jump.c will not duplicate the exit test for the outer
442 loop, so it will start with a jump to the exit code.
444 Then consider if the inner loop turns out to iterate once and
445 only once. We will end up deleting the jumps associated with
446 the inner loop. However, the loop notes are not removed from
447 the instruction stream.
449 And finally assume that we can compute the number of iterations
452 In this case unroll may want to unroll the outer loop even though
453 it starts with a jump to the outer loop's exit code.
455 We could try to optimize this case, but it hardly seems worth it.
456 Just return without unrolling the loop in such cases. */
459 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
460 insn = NEXT_INSN (insn);
461 if (GET_CODE (insn) == JUMP_INSN)
465 if (unroll_type == UNROLL_COMPLETELY)
467 /* Completely unrolling the loop: Delete the compare and branch at
468 the end (the last two instructions). This delete must done at the
469 very end of loop unrolling, to avoid problems with calls to
470 back_branch_in_range_p, which is called by find_splittable_regs.
471 All increments of splittable bivs/givs are changed to load constant
474 copy_start = loop_start;
476 /* Set insert_before to the instruction immediately after the JUMP_INSN
477 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
478 the loop will be correctly handled by copy_loop_body. */
479 insert_before = NEXT_INSN (last_loop_insn);
481 /* Set copy_end to the insn before the jump at the end of the loop. */
482 if (GET_CODE (last_loop_insn) == BARRIER)
483 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
484 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
486 copy_end = PREV_INSN (last_loop_insn);
488 /* The instruction immediately before the JUMP_INSN may be a compare
489 instruction which we do not want to copy. */
490 if (sets_cc0_p (PREV_INSN (copy_end)))
491 copy_end = PREV_INSN (copy_end);
496 /* We currently can't unroll a loop if it doesn't end with a
497 JUMP_INSN. There would need to be a mechanism that recognizes
498 this case, and then inserts a jump after each loop body, which
499 jumps to after the last loop body. */
500 if (loop_dump_stream)
501 fprintf (loop_dump_stream,
502 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
506 else if (unroll_type == UNROLL_MODULO)
508 /* Partially unrolling the loop: The compare and branch at the end
509 (the last two instructions) must remain. Don't copy the compare
510 and branch instructions at the end of the loop. Insert the unrolled
511 code immediately before the compare/branch at the end so that the
512 code will fall through to them as before. */
514 copy_start = loop_start;
516 /* Set insert_before to the jump insn at the end of the loop.
517 Set copy_end to before the jump insn at the end of the loop. */
518 if (GET_CODE (last_loop_insn) == BARRIER)
520 insert_before = PREV_INSN (last_loop_insn);
521 copy_end = PREV_INSN (insert_before);
523 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
525 insert_before = last_loop_insn;
527 /* The instruction immediately before the JUMP_INSN may be a compare
528 instruction which we do not want to copy or delete. */
529 if (sets_cc0_p (PREV_INSN (insert_before)))
530 insert_before = PREV_INSN (insert_before);
532 copy_end = PREV_INSN (insert_before);
536 /* We currently can't unroll a loop if it doesn't end with a
537 JUMP_INSN. There would need to be a mechanism that recognizes
538 this case, and then inserts a jump after each loop body, which
539 jumps to after the last loop body. */
540 if (loop_dump_stream)
541 fprintf (loop_dump_stream,
542 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
548 /* Normal case: Must copy the compare and branch instructions at the
551 if (GET_CODE (last_loop_insn) == BARRIER)
553 /* Loop ends with an unconditional jump and a barrier.
554 Handle this like above, don't copy jump and barrier.
555 This is not strictly necessary, but doing so prevents generating
556 unconditional jumps to an immediately following label.
558 This will be corrected below if the target of this jump is
559 not the start_label. */
561 insert_before = PREV_INSN (last_loop_insn);
562 copy_end = PREV_INSN (insert_before);
564 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
566 /* Set insert_before to immediately after the JUMP_INSN, so that
567 NOTEs at the end of the loop will be correctly handled by
569 insert_before = NEXT_INSN (last_loop_insn);
570 copy_end = last_loop_insn;
574 /* We currently can't unroll a loop if it doesn't end with a
575 JUMP_INSN. There would need to be a mechanism that recognizes
576 this case, and then inserts a jump after each loop body, which
577 jumps to after the last loop body. */
578 if (loop_dump_stream)
579 fprintf (loop_dump_stream,
580 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
584 /* If copying exit test branches because they can not be eliminated,
585 then must convert the fall through case of the branch to a jump past
586 the end of the loop. Create a label to emit after the loop and save
587 it for later use. Do not use the label after the loop, if any, since
588 it might be used by insns outside the loop, or there might be insns
589 added before it later by final_[bg]iv_value which must be after
590 the real exit label. */
591 exit_label = gen_label_rtx ();
594 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
595 insn = NEXT_INSN (insn);
597 if (GET_CODE (insn) == JUMP_INSN)
599 /* The loop starts with a jump down to the exit condition test.
600 Start copying the loop after the barrier following this
602 copy_start = NEXT_INSN (insn);
604 /* Splitting induction variables doesn't work when the loop is
605 entered via a jump to the bottom, because then we end up doing
606 a comparison against a new register for a split variable, but
607 we did not execute the set insn for the new register because
608 it was skipped over. */
609 splitting_not_safe = 1;
610 if (loop_dump_stream)
611 fprintf (loop_dump_stream,
612 "Splitting not safe, because loop not entered at top.\n");
615 copy_start = loop_start;
618 /* This should always be the first label in the loop. */
619 start_label = NEXT_INSN (copy_start);
620 /* There may be a line number note and/or a loop continue note here. */
621 while (GET_CODE (start_label) == NOTE)
622 start_label = NEXT_INSN (start_label);
623 if (GET_CODE (start_label) != CODE_LABEL)
625 /* This can happen as a result of jump threading. If the first insns in
626 the loop test the same condition as the loop's backward jump, or the
627 opposite condition, then the backward jump will be modified to point
628 to elsewhere, and the loop's start label is deleted.
630 This case currently can not be handled by the loop unrolling code. */
632 if (loop_dump_stream)
633 fprintf (loop_dump_stream,
634 "Unrolling failure: unknown insns between BEG note and loop label.\n");
637 if (LABEL_NAME (start_label))
639 /* The jump optimization pass must have combined the original start label
640 with a named label for a goto. We can't unroll this case because
641 jumps which go to the named label must be handled differently than
642 jumps to the loop start, and it is impossible to differentiate them
644 if (loop_dump_stream)
645 fprintf (loop_dump_stream,
646 "Unrolling failure: loop start label is gone\n");
650 if (unroll_type == UNROLL_NAIVE
651 && GET_CODE (last_loop_insn) == BARRIER
652 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
653 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
655 /* In this case, we must copy the jump and barrier, because they will
656 not be converted to jumps to an immediately following label. */
658 insert_before = NEXT_INSN (last_loop_insn);
659 copy_end = last_loop_insn;
662 if (unroll_type == UNROLL_NAIVE
663 && GET_CODE (last_loop_insn) == JUMP_INSN
664 && start_label != JUMP_LABEL (last_loop_insn))
666 /* ??? The loop ends with a conditional branch that does not branch back
667 to the loop start label. In this case, we must emit an unconditional
668 branch to the loop exit after emitting the final branch.
669 copy_loop_body does not have support for this currently, so we
670 give up. It doesn't seem worthwhile to unroll anyways since
671 unrolling would increase the number of branch instructions
673 if (loop_dump_stream)
674 fprintf (loop_dump_stream,
675 "Unrolling failure: final conditional branch not to loop start\n");
679 /* Allocate a translation table for the labels and insn numbers.
680 They will be filled in as we copy the insns in the loop. */
682 max_labelno = max_label_num ();
683 max_insnno = get_max_uid ();
685 /* Various paths through the unroll code may reach the "egress" label
686 without initializing fields within the map structure.
688 To be safe, we use xcalloc to zero the memory. */
689 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
691 /* Allocate the label map. */
695 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
697 local_label = (char *) xcalloc (max_labelno, sizeof (char));
700 /* Search the loop and mark all local labels, i.e. the ones which have to
701 be distinct labels when copied. For all labels which might be
702 non-local, set their label_map entries to point to themselves.
703 If they happen to be local their label_map entries will be overwritten
704 before the loop body is copied. The label_map entries for local labels
705 will be set to a different value each time the loop body is copied. */
707 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
711 if (GET_CODE (insn) == CODE_LABEL)
712 local_label[CODE_LABEL_NUMBER (insn)] = 1;
713 else if (GET_CODE (insn) == JUMP_INSN)
715 if (JUMP_LABEL (insn))
716 set_label_in_map (map,
717 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
719 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
720 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
722 rtx pat = PATTERN (insn);
723 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
724 int len = XVECLEN (pat, diff_vec_p);
727 for (i = 0; i < len; i++)
729 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
730 set_label_in_map (map,
731 CODE_LABEL_NUMBER (label),
736 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
737 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
741 /* Allocate space for the insn map. */
743 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
745 /* Set this to zero, to indicate that we are doing loop unrolling,
746 not function inlining. */
747 map->inline_target = 0;
749 /* The register and constant maps depend on the number of registers
750 present, so the final maps can't be created until after
751 find_splittable_regs is called. However, they are needed for
752 preconditioning, so we create temporary maps when preconditioning
755 /* The preconditioning code may allocate two new pseudo registers. */
756 maxregnum = max_reg_num ();
758 /* local_regno is only valid for regnos < max_local_regnum. */
759 max_local_regnum = maxregnum;
761 /* Allocate and zero out the splittable_regs and addr_combined_regs
762 arrays. These must be zeroed here because they will be used if
763 loop preconditioning is performed, and must be zero for that case.
765 It is safe to do this here, since the extra registers created by the
766 preconditioning code and find_splittable_regs will never be used
767 to access the splittable_regs[] and addr_combined_regs[] arrays. */
769 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
770 derived_regs = (char *) xcalloc (maxregnum, sizeof (char));
771 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
773 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
774 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
776 /* Mark all local registers, i.e. the ones which are referenced only
778 if (INSN_UID (copy_end) < max_uid_for_loop)
780 int copy_start_luid = INSN_LUID (copy_start);
781 int copy_end_luid = INSN_LUID (copy_end);
783 /* If a register is used in the jump insn, we must not duplicate it
784 since it will also be used outside the loop. */
785 if (GET_CODE (copy_end) == JUMP_INSN)
788 /* If we have a target that uses cc0, then we also must not duplicate
789 the insn that sets cc0 before the jump insn, if one is present. */
791 if (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
795 /* If copy_start points to the NOTE that starts the loop, then we must
796 use the next luid, because invariant pseudo-regs moved out of the loop
797 have their lifetimes modified to start here, but they are not safe
799 if (copy_start == loop_start)
802 /* If a pseudo's lifetime is entirely contained within this loop, then we
803 can use a different pseudo in each unrolled copy of the loop. This
804 results in better code. */
805 /* We must limit the generic test to max_reg_before_loop, because only
806 these pseudo registers have valid regno_first_uid info. */
807 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
808 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
809 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
810 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
811 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
813 /* However, we must also check for loop-carried dependencies.
814 If the value the pseudo has at the end of iteration X is
815 used by iteration X+1, then we can not use a different pseudo
816 for each unrolled copy of the loop. */
817 /* A pseudo is safe if regno_first_uid is a set, and this
818 set dominates all instructions from regno_first_uid to
820 /* ??? This check is simplistic. We would get better code if
821 this check was more sophisticated. */
822 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
823 copy_start, copy_end))
826 if (loop_dump_stream)
829 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
831 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
835 /* Givs that have been created from multiple biv increments always have
837 for (j = first_increment_giv; j <= last_increment_giv; j++)
840 if (loop_dump_stream)
841 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
845 /* If this loop requires exit tests when unrolled, check to see if we
846 can precondition the loop so as to make the exit tests unnecessary.
847 Just like variable splitting, this is not safe if the loop is entered
848 via a jump to the bottom. Also, can not do this if no strength
849 reduce info, because precondition_loop_p uses this info. */
851 /* Must copy the loop body for preconditioning before the following
852 find_splittable_regs call since that will emit insns which need to
853 be after the preconditioned loop copies, but immediately before the
854 unrolled loop copies. */
856 /* Also, it is not safe to split induction variables for the preconditioned
857 copies of the loop body. If we split induction variables, then the code
858 assumes that each induction variable can be represented as a function
859 of its initial value and the loop iteration number. This is not true
860 in this case, because the last preconditioned copy of the loop body
861 could be any iteration from the first up to the `unroll_number-1'th,
862 depending on the initial value of the iteration variable. Therefore
863 we can not split induction variables here, because we can not calculate
864 their value. Hence, this code must occur before find_splittable_regs
867 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
869 rtx initial_value, final_value, increment;
870 enum machine_mode mode;
872 if (precondition_loop_p (loop_start, loop_info,
873 &initial_value, &final_value, &increment,
878 int abs_inc, neg_inc;
880 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
882 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
884 global_const_equiv_varray = map->const_equiv_varray;
886 init_reg_map (map, maxregnum);
888 /* Limit loop unrolling to 4, since this will make 7 copies of
890 if (unroll_number > 4)
893 /* Save the absolute value of the increment, and also whether or
894 not it is negative. */
896 abs_inc = INTVAL (increment);
905 /* Calculate the difference between the final and initial values.
906 Final value may be a (plus (reg x) (const_int 1)) rtx.
907 Let the following cse pass simplify this if initial value is
910 We must copy the final and initial values here to avoid
911 improperly shared rtl. */
913 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
914 copy_rtx (initial_value), NULL_RTX, 0,
917 /* Now calculate (diff % (unroll * abs (increment))) by using an
919 diff = expand_binop (GET_MODE (diff), and_optab, diff,
920 GEN_INT (unroll_number * abs_inc - 1),
921 NULL_RTX, 0, OPTAB_LIB_WIDEN);
923 /* Now emit a sequence of branches to jump to the proper precond
926 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
927 for (i = 0; i < unroll_number; i++)
928 labels[i] = gen_label_rtx ();
930 /* Check for the case where the initial value is greater than or
931 equal to the final value. In that case, we want to execute
932 exactly one loop iteration. The code below will fail for this
933 case. This check does not apply if the loop has a NE
934 comparison at the end. */
936 if (loop_info->comparison_code != NE)
938 emit_cmp_and_jump_insns (initial_value, final_value,
940 NULL_RTX, mode, 0, 0, labels[1]);
941 JUMP_LABEL (get_last_insn ()) = labels[1];
942 LABEL_NUSES (labels[1])++;
945 /* Assuming the unroll_number is 4, and the increment is 2, then
946 for a negative increment: for a positive increment:
947 diff = 0,1 precond 0 diff = 0,7 precond 0
948 diff = 2,3 precond 3 diff = 1,2 precond 1
949 diff = 4,5 precond 2 diff = 3,4 precond 2
950 diff = 6,7 precond 1 diff = 5,6 precond 3 */
952 /* We only need to emit (unroll_number - 1) branches here, the
953 last case just falls through to the following code. */
955 /* ??? This would give better code if we emitted a tree of branches
956 instead of the current linear list of branches. */
958 for (i = 0; i < unroll_number - 1; i++)
961 enum rtx_code cmp_code;
963 /* For negative increments, must invert the constant compared
964 against, except when comparing against zero. */
972 cmp_const = unroll_number - i;
981 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
982 cmp_code, NULL_RTX, mode, 0, 0,
984 JUMP_LABEL (get_last_insn ()) = labels[i];
985 LABEL_NUSES (labels[i])++;
988 /* If the increment is greater than one, then we need another branch,
989 to handle other cases equivalent to 0. */
991 /* ??? This should be merged into the code above somehow to help
992 simplify the code here, and reduce the number of branches emitted.
993 For the negative increment case, the branch here could easily
994 be merged with the `0' case branch above. For the positive
995 increment case, it is not clear how this can be simplified. */
1000 enum rtx_code cmp_code;
1004 cmp_const = abs_inc - 1;
1009 cmp_const = abs_inc * (unroll_number - 1) + 1;
1013 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1014 NULL_RTX, mode, 0, 0, labels[0]);
1015 JUMP_LABEL (get_last_insn ()) = labels[0];
1016 LABEL_NUSES (labels[0])++;
1019 sequence = gen_sequence ();
1021 emit_insn_before (sequence, loop_start);
1023 /* Only the last copy of the loop body here needs the exit
1024 test, so set copy_end to exclude the compare/branch here,
1025 and then reset it inside the loop when get to the last
1028 if (GET_CODE (last_loop_insn) == BARRIER)
1029 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1030 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1032 copy_end = PREV_INSN (last_loop_insn);
1034 /* The immediately preceding insn may be a compare which we do not
1036 if (sets_cc0_p (PREV_INSN (copy_end)))
1037 copy_end = PREV_INSN (copy_end);
1043 for (i = 1; i < unroll_number; i++)
1045 emit_label_after (labels[unroll_number - i],
1046 PREV_INSN (loop_start));
1048 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1049 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1050 (VARRAY_SIZE (map->const_equiv_varray)
1051 * sizeof (struct const_equiv_data)));
1054 for (j = 0; j < max_labelno; j++)
1056 set_label_in_map (map, j, gen_label_rtx ());
1058 for (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
1061 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1062 record_base_value (REGNO (map->reg_map[j]),
1063 regno_reg_rtx[j], 0);
1065 /* The last copy needs the compare/branch insns at the end,
1066 so reset copy_end here if the loop ends with a conditional
1069 if (i == unroll_number - 1)
1071 if (GET_CODE (last_loop_insn) == BARRIER)
1072 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1074 copy_end = last_loop_insn;
1077 /* None of the copies are the `last_iteration', so just
1078 pass zero for that parameter. */
1079 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1080 unroll_type, start_label, loop_end,
1081 loop_start, copy_end);
1083 emit_label_after (labels[0], PREV_INSN (loop_start));
1085 if (GET_CODE (last_loop_insn) == BARRIER)
1087 insert_before = PREV_INSN (last_loop_insn);
1088 copy_end = PREV_INSN (insert_before);
1092 insert_before = last_loop_insn;
1094 /* The instruction immediately before the JUMP_INSN may be a compare
1095 instruction which we do not want to copy or delete. */
1096 if (sets_cc0_p (PREV_INSN (insert_before)))
1097 insert_before = PREV_INSN (insert_before);
1099 copy_end = PREV_INSN (insert_before);
1102 /* Set unroll type to MODULO now. */
1103 unroll_type = UNROLL_MODULO;
1104 loop_preconditioned = 1;
1111 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1112 the loop unless all loops are being unrolled. */
1113 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1115 if (loop_dump_stream)
1116 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1120 /* At this point, we are guaranteed to unroll the loop. */
1122 /* Keep track of the unroll factor for the loop. */
1123 loop_info->unroll_number = unroll_number;
1125 /* For each biv and giv, determine whether it can be safely split into
1126 a different variable for each unrolled copy of the loop body.
1127 We precalculate and save this info here, since computing it is
1130 Do this before deleting any instructions from the loop, so that
1131 back_branch_in_range_p will work correctly. */
1133 if (splitting_not_safe)
1136 temp = find_splittable_regs (unroll_type, loop_start, loop_end,
1137 end_insert_before, unroll_number,
1138 loop_info->n_iterations);
1140 /* find_splittable_regs may have created some new registers, so must
1141 reallocate the reg_map with the new larger size, and must realloc
1142 the constant maps also. */
1144 maxregnum = max_reg_num ();
1145 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1147 init_reg_map (map, maxregnum);
1149 if (map->const_equiv_varray == 0)
1150 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1151 maxregnum + temp * unroll_number * 2,
1153 global_const_equiv_varray = map->const_equiv_varray;
1155 /* Search the list of bivs and givs to find ones which need to be remapped
1156 when split, and set their reg_map entry appropriately. */
1158 for (bl = loop_iv_list; bl; bl = bl->next)
1160 if (REGNO (bl->biv->src_reg) != bl->regno)
1161 map->reg_map[bl->regno] = bl->biv->src_reg;
1163 /* Currently, non-reduced/final-value givs are never split. */
1164 for (v = bl->giv; v; v = v->next_iv)
1165 if (REGNO (v->src_reg) != bl->regno)
1166 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1170 /* Use our current register alignment and pointer flags. */
1171 map->regno_pointer_flag = current_function->emit->regno_pointer_flag;
1172 map->regno_pointer_align = current_function->emit->regno_pointer_align;
1174 /* If the loop is being partially unrolled, and the iteration variables
1175 are being split, and are being renamed for the split, then must fix up
1176 the compare/jump instruction at the end of the loop to refer to the new
1177 registers. This compare isn't copied, so the registers used in it
1178 will never be replaced if it isn't done here. */
1180 if (unroll_type == UNROLL_MODULO)
1182 insn = NEXT_INSN (copy_end);
1183 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1184 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1187 /* For unroll_number times, make a copy of each instruction
1188 between copy_start and copy_end, and insert these new instructions
1189 before the end of the loop. */
1191 for (i = 0; i < unroll_number; i++)
1193 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1194 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1195 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1198 for (j = 0; j < max_labelno; j++)
1200 set_label_in_map (map, j, gen_label_rtx ());
1202 for (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
1205 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1206 record_base_value (REGNO (map->reg_map[j]),
1207 regno_reg_rtx[j], 0);
1210 /* If loop starts with a branch to the test, then fix it so that
1211 it points to the test of the first unrolled copy of the loop. */
1212 if (i == 0 && loop_start != copy_start)
1214 insn = PREV_INSN (copy_start);
1215 pattern = PATTERN (insn);
1217 tem = get_label_from_map (map,
1219 (XEXP (SET_SRC (pattern), 0)));
1220 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1222 /* Set the jump label so that it can be used by later loop unrolling
1224 JUMP_LABEL (insn) = tem;
1225 LABEL_NUSES (tem)++;
1228 copy_loop_body (copy_start, copy_end, map, exit_label,
1229 i == unroll_number - 1, unroll_type, start_label,
1230 loop_end, insert_before, insert_before);
1233 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1234 insn to be deleted. This prevents any runaway delete_insn call from
1235 more insns that it should, as it always stops at a CODE_LABEL. */
1237 /* Delete the compare and branch at the end of the loop if completely
1238 unrolling the loop. Deleting the backward branch at the end also
1239 deletes the code label at the start of the loop. This is done at
1240 the very end to avoid problems with back_branch_in_range_p. */
1242 if (unroll_type == UNROLL_COMPLETELY)
1243 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1245 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1247 /* Delete all of the original loop instructions. Don't delete the
1248 LOOP_BEG note, or the first code label in the loop. */
1250 insn = NEXT_INSN (copy_start);
1251 while (insn != safety_label)
1253 /* ??? Don't delete named code labels. They will be deleted when the
1254 jump that references them is deleted. Otherwise, we end up deleting
1255 them twice, which causes them to completely disappear instead of turn
1256 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1257 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1258 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1259 associated LABEL_DECL to point to one of the new label instances. */
1260 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1261 if (insn != start_label
1262 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1263 && ! (GET_CODE (insn) == NOTE
1264 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1265 insn = delete_insn (insn);
1267 insn = NEXT_INSN (insn);
1270 /* Can now delete the 'safety' label emitted to protect us from runaway
1271 delete_insn calls. */
1272 if (INSN_DELETED_P (safety_label))
1274 delete_insn (safety_label);
1276 /* If exit_label exists, emit it after the loop. Doing the emit here
1277 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1278 This is needed so that mostly_true_jump in reorg.c will treat jumps
1279 to this loop end label correctly, i.e. predict that they are usually
1282 emit_label_after (exit_label, loop_end);
1285 if (map->const_equiv_varray)
1286 VARRAY_FREE (map->const_equiv_varray);
1289 free (map->label_map);
1292 free (map->insn_map);
1293 free (splittable_regs);
1294 free (derived_regs);
1295 free (splittable_regs_updates);
1296 free (addr_combined_regs);
1299 free (map->reg_map);
1303 /* Return true if the loop can be safely, and profitably, preconditioned
1304 so that the unrolled copies of the loop body don't need exit tests.
1306 This only works if final_value, initial_value and increment can be
1307 determined, and if increment is a constant power of 2.
1308 If increment is not a power of 2, then the preconditioning modulo
1309 operation would require a real modulo instead of a boolean AND, and this
1310 is not considered `profitable'. */
1312 /* ??? If the loop is known to be executed very many times, or the machine
1313 has a very cheap divide instruction, then preconditioning is a win even
1314 when the increment is not a power of 2. Use RTX_COST to compute
1315 whether divide is cheap.
1316 ??? A divide by constant doesn't actually need a divide, look at
1317 expand_divmod. The reduced cost of this optimized modulo is not
1318 reflected in RTX_COST. */
1321 precondition_loop_p (loop_start, loop_info,
1322 initial_value, final_value, increment, mode)
1324 struct loop_info *loop_info;
1325 rtx *initial_value, *final_value, *increment;
1326 enum machine_mode *mode;
1329 if (loop_info->n_iterations > 0)
1331 *initial_value = const0_rtx;
1332 *increment = const1_rtx;
1333 *final_value = GEN_INT (loop_info->n_iterations);
1336 if (loop_dump_stream)
1338 fputs ("Preconditioning: Success, number of iterations known, ",
1340 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1341 loop_info->n_iterations);
1342 fputs (".\n", loop_dump_stream);
1347 if (loop_info->initial_value == 0)
1349 if (loop_dump_stream)
1350 fprintf (loop_dump_stream,
1351 "Preconditioning: Could not find initial value.\n");
1354 else if (loop_info->increment == 0)
1356 if (loop_dump_stream)
1357 fprintf (loop_dump_stream,
1358 "Preconditioning: Could not find increment value.\n");
1361 else if (GET_CODE (loop_info->increment) != CONST_INT)
1363 if (loop_dump_stream)
1364 fprintf (loop_dump_stream,
1365 "Preconditioning: Increment not a constant.\n");
1368 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1369 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1371 if (loop_dump_stream)
1372 fprintf (loop_dump_stream,
1373 "Preconditioning: Increment not a constant power of 2.\n");
1377 /* Unsigned_compare and compare_dir can be ignored here, since they do
1378 not matter for preconditioning. */
1380 if (loop_info->final_value == 0)
1382 if (loop_dump_stream)
1383 fprintf (loop_dump_stream,
1384 "Preconditioning: EQ comparison loop.\n");
1388 /* Must ensure that final_value is invariant, so call invariant_p to
1389 check. Before doing so, must check regno against max_reg_before_loop
1390 to make sure that the register is in the range covered by invariant_p.
1391 If it isn't, then it is most likely a biv/giv which by definition are
1393 if ((GET_CODE (loop_info->final_value) == REG
1394 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1395 || (GET_CODE (loop_info->final_value) == PLUS
1396 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1397 || ! invariant_p (loop_info->final_value))
1399 if (loop_dump_stream)
1400 fprintf (loop_dump_stream,
1401 "Preconditioning: Final value not invariant.\n");
1405 /* Fail for floating point values, since the caller of this function
1406 does not have code to deal with them. */
1407 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1408 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1410 if (loop_dump_stream)
1411 fprintf (loop_dump_stream,
1412 "Preconditioning: Floating point final or initial value.\n");
1416 /* Fail if loop_info->iteration_var is not live before loop_start,
1417 since we need to test its value in the preconditioning code. */
1419 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1420 > INSN_LUID (loop_start))
1422 if (loop_dump_stream)
1423 fprintf (loop_dump_stream,
1424 "Preconditioning: Iteration var not live before loop start.\n");
1428 /* Note that iteration_info biases the initial value for GIV iterators
1429 such as "while (i-- > 0)" so that we can calculate the number of
1430 iterations just like for BIV iterators.
1432 Also note that the absolute values of initial_value and
1433 final_value are unimportant as only their difference is used for
1434 calculating the number of loop iterations. */
1435 *initial_value = loop_info->initial_value;
1436 *increment = loop_info->increment;
1437 *final_value = loop_info->final_value;
1439 /* Decide what mode to do these calculations in. Choose the larger
1440 of final_value's mode and initial_value's mode, or a full-word if
1441 both are constants. */
1442 *mode = GET_MODE (*final_value);
1443 if (*mode == VOIDmode)
1445 *mode = GET_MODE (*initial_value);
1446 if (*mode == VOIDmode)
1449 else if (*mode != GET_MODE (*initial_value)
1450 && (GET_MODE_SIZE (*mode)
1451 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1452 *mode = GET_MODE (*initial_value);
1455 if (loop_dump_stream)
1456 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1461 /* All pseudo-registers must be mapped to themselves. Two hard registers
1462 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1463 REGNUM, to avoid function-inlining specific conversions of these
1464 registers. All other hard regs can not be mapped because they may be
1469 init_reg_map (map, maxregnum)
1470 struct inline_remap *map;
1475 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1476 map->reg_map[i] = regno_reg_rtx[i];
1477 /* Just clear the rest of the entries. */
1478 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1479 map->reg_map[i] = 0;
1481 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1482 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1483 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1484 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1487 /* Strength-reduction will often emit code for optimized biv/givs which
1488 calculates their value in a temporary register, and then copies the result
1489 to the iv. This procedure reconstructs the pattern computing the iv;
1490 verifying that all operands are of the proper form.
1492 PATTERN must be the result of single_set.
1493 The return value is the amount that the giv is incremented by. */
1496 calculate_giv_inc (pattern, src_insn, regno)
1497 rtx pattern, src_insn;
1501 rtx increment_total = 0;
1505 /* Verify that we have an increment insn here. First check for a plus
1506 as the set source. */
1507 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1509 /* SR sometimes computes the new giv value in a temp, then copies it
1511 src_insn = PREV_INSN (src_insn);
1512 pattern = PATTERN (src_insn);
1513 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1516 /* The last insn emitted is not needed, so delete it to avoid confusing
1517 the second cse pass. This insn sets the giv unnecessarily. */
1518 delete_insn (get_last_insn ());
1521 /* Verify that we have a constant as the second operand of the plus. */
1522 increment = XEXP (SET_SRC (pattern), 1);
1523 if (GET_CODE (increment) != CONST_INT)
1525 /* SR sometimes puts the constant in a register, especially if it is
1526 too big to be an add immed operand. */
1527 src_insn = PREV_INSN (src_insn);
1528 increment = SET_SRC (PATTERN (src_insn));
1530 /* SR may have used LO_SUM to compute the constant if it is too large
1531 for a load immed operand. In this case, the constant is in operand
1532 one of the LO_SUM rtx. */
1533 if (GET_CODE (increment) == LO_SUM)
1534 increment = XEXP (increment, 1);
1536 /* Some ports store large constants in memory and add a REG_EQUAL
1537 note to the store insn. */
1538 else if (GET_CODE (increment) == MEM)
1540 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1542 increment = XEXP (note, 0);
1545 else if (GET_CODE (increment) == IOR
1546 || GET_CODE (increment) == ASHIFT
1547 || GET_CODE (increment) == PLUS)
1549 /* The rs6000 port loads some constants with IOR.
1550 The alpha port loads some constants with ASHIFT and PLUS. */
1551 rtx second_part = XEXP (increment, 1);
1552 enum rtx_code code = GET_CODE (increment);
1554 src_insn = PREV_INSN (src_insn);
1555 increment = SET_SRC (PATTERN (src_insn));
1556 /* Don't need the last insn anymore. */
1557 delete_insn (get_last_insn ());
1559 if (GET_CODE (second_part) != CONST_INT
1560 || GET_CODE (increment) != CONST_INT)
1564 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1565 else if (code == PLUS)
1566 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1568 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1571 if (GET_CODE (increment) != CONST_INT)
1574 /* The insn loading the constant into a register is no longer needed,
1576 delete_insn (get_last_insn ());
1579 if (increment_total)
1580 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1582 increment_total = increment;
1584 /* Check that the source register is the same as the register we expected
1585 to see as the source. If not, something is seriously wrong. */
1586 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1587 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1589 /* Some machines (e.g. the romp), may emit two add instructions for
1590 certain constants, so lets try looking for another add immediately
1591 before this one if we have only seen one add insn so far. */
1597 src_insn = PREV_INSN (src_insn);
1598 pattern = PATTERN (src_insn);
1600 delete_insn (get_last_insn ());
1608 return increment_total;
1611 /* Copy REG_NOTES, except for insn references, because not all insn_map
1612 entries are valid yet. We do need to copy registers now though, because
1613 the reg_map entries can change during copying. */
1616 initial_reg_note_copy (notes, map)
1618 struct inline_remap *map;
1625 copy = rtx_alloc (GET_CODE (notes));
1626 PUT_MODE (copy, GET_MODE (notes));
1628 if (GET_CODE (notes) == EXPR_LIST)
1629 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1630 else if (GET_CODE (notes) == INSN_LIST)
1631 /* Don't substitute for these yet. */
1632 XEXP (copy, 0) = XEXP (notes, 0);
1636 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1641 /* Fixup insn references in copied REG_NOTES. */
1644 final_reg_note_copy (notes, map)
1646 struct inline_remap *map;
1650 for (note = notes; note; note = XEXP (note, 1))
1651 if (GET_CODE (note) == INSN_LIST)
1652 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1655 /* Copy each instruction in the loop, substituting from map as appropriate.
1656 This is very similar to a loop in expand_inline_function. */
1659 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1660 unroll_type, start_label, loop_end, insert_before,
1662 rtx copy_start, copy_end;
1663 struct inline_remap *map;
1666 enum unroll_types unroll_type;
1667 rtx start_label, loop_end, insert_before, copy_notes_from;
1671 int dest_reg_was_split, i;
1675 rtx final_label = 0;
1676 rtx giv_inc, giv_dest_reg, giv_src_reg;
1678 /* If this isn't the last iteration, then map any references to the
1679 start_label to final_label. Final label will then be emitted immediately
1680 after the end of this loop body if it was ever used.
1682 If this is the last iteration, then map references to the start_label
1684 if (! last_iteration)
1686 final_label = gen_label_rtx ();
1687 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1691 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1695 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1696 Else gen_sequence could return a raw pattern for a jump which we pass
1697 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1698 a variety of losing behaviors later. */
1699 emit_note (0, NOTE_INSN_DELETED);
1704 insn = NEXT_INSN (insn);
1706 map->orig_asm_operands_vector = 0;
1708 switch (GET_CODE (insn))
1711 pattern = PATTERN (insn);
1715 /* Check to see if this is a giv that has been combined with
1716 some split address givs. (Combined in the sense that
1717 `combine_givs' in loop.c has put two givs in the same register.)
1718 In this case, we must search all givs based on the same biv to
1719 find the address givs. Then split the address givs.
1720 Do this before splitting the giv, since that may map the
1721 SET_DEST to a new register. */
1723 if ((set = single_set (insn))
1724 && GET_CODE (SET_DEST (set)) == REG
1725 && addr_combined_regs[REGNO (SET_DEST (set))])
1727 struct iv_class *bl;
1728 struct induction *v, *tv;
1729 int regno = REGNO (SET_DEST (set));
1731 v = addr_combined_regs[REGNO (SET_DEST (set))];
1732 bl = reg_biv_class[REGNO (v->src_reg)];
1734 /* Although the giv_inc amount is not needed here, we must call
1735 calculate_giv_inc here since it might try to delete the
1736 last insn emitted. If we wait until later to call it,
1737 we might accidentally delete insns generated immediately
1738 below by emit_unrolled_add. */
1740 if (! derived_regs[regno])
1741 giv_inc = calculate_giv_inc (set, insn, regno);
1743 /* Now find all address giv's that were combined with this
1745 for (tv = bl->giv; tv; tv = tv->next_iv)
1746 if (tv->giv_type == DEST_ADDR && tv->same == v)
1750 /* If this DEST_ADDR giv was not split, then ignore it. */
1751 if (*tv->location != tv->dest_reg)
1754 /* Scale this_giv_inc if the multiplicative factors of
1755 the two givs are different. */
1756 this_giv_inc = INTVAL (giv_inc);
1757 if (tv->mult_val != v->mult_val)
1758 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1759 * INTVAL (tv->mult_val));
1761 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1762 *tv->location = tv->dest_reg;
1764 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1766 /* Must emit an insn to increment the split address
1767 giv. Add in the const_adjust field in case there
1768 was a constant eliminated from the address. */
1769 rtx value, dest_reg;
1771 /* tv->dest_reg will be either a bare register,
1772 or else a register plus a constant. */
1773 if (GET_CODE (tv->dest_reg) == REG)
1774 dest_reg = tv->dest_reg;
1776 dest_reg = XEXP (tv->dest_reg, 0);
1778 /* Check for shared address givs, and avoid
1779 incrementing the shared pseudo reg more than
1781 if (! tv->same_insn && ! tv->shared)
1783 /* tv->dest_reg may actually be a (PLUS (REG)
1784 (CONST)) here, so we must call plus_constant
1785 to add the const_adjust amount before calling
1786 emit_unrolled_add below. */
1787 value = plus_constant (tv->dest_reg,
1790 /* The constant could be too large for an add
1791 immediate, so can't directly emit an insn
1793 emit_unrolled_add (dest_reg, XEXP (value, 0),
1797 /* Reset the giv to be just the register again, in case
1798 it is used after the set we have just emitted.
1799 We must subtract the const_adjust factor added in
1801 tv->dest_reg = plus_constant (dest_reg,
1802 - tv->const_adjust);
1803 *tv->location = tv->dest_reg;
1808 /* If this is a setting of a splittable variable, then determine
1809 how to split the variable, create a new set based on this split,
1810 and set up the reg_map so that later uses of the variable will
1811 use the new split variable. */
1813 dest_reg_was_split = 0;
1815 if ((set = single_set (insn))
1816 && GET_CODE (SET_DEST (set)) == REG
1817 && splittable_regs[REGNO (SET_DEST (set))])
1819 int regno = REGNO (SET_DEST (set));
1822 dest_reg_was_split = 1;
1824 giv_dest_reg = SET_DEST (set);
1825 if (derived_regs[regno])
1827 /* ??? This relies on SET_SRC (SET) to be of
1828 the form (plus (reg) (const_int)), and thus
1829 forces recombine_givs to restrict the kind
1830 of giv derivations it does before unrolling. */
1831 giv_src_reg = XEXP (SET_SRC (set), 0);
1832 giv_inc = XEXP (SET_SRC (set), 1);
1836 giv_src_reg = giv_dest_reg;
1837 /* Compute the increment value for the giv, if it wasn't
1838 already computed above. */
1840 giv_inc = calculate_giv_inc (set, insn, regno);
1842 src_regno = REGNO (giv_src_reg);
1844 if (unroll_type == UNROLL_COMPLETELY)
1846 /* Completely unrolling the loop. Set the induction
1847 variable to a known constant value. */
1849 /* The value in splittable_regs may be an invariant
1850 value, so we must use plus_constant here. */
1851 splittable_regs[regno]
1852 = plus_constant (splittable_regs[src_regno],
1855 if (GET_CODE (splittable_regs[regno]) == PLUS)
1857 giv_src_reg = XEXP (splittable_regs[regno], 0);
1858 giv_inc = XEXP (splittable_regs[regno], 1);
1862 /* The splittable_regs value must be a REG or a
1863 CONST_INT, so put the entire value in the giv_src_reg
1865 giv_src_reg = splittable_regs[regno];
1866 giv_inc = const0_rtx;
1871 /* Partially unrolling loop. Create a new pseudo
1872 register for the iteration variable, and set it to
1873 be a constant plus the original register. Except
1874 on the last iteration, when the result has to
1875 go back into the original iteration var register. */
1877 /* Handle bivs which must be mapped to a new register
1878 when split. This happens for bivs which need their
1879 final value set before loop entry. The new register
1880 for the biv was stored in the biv's first struct
1881 induction entry by find_splittable_regs. */
1883 if (regno < max_reg_before_loop
1884 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1886 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1887 giv_dest_reg = giv_src_reg;
1891 /* If non-reduced/final-value givs were split, then
1892 this would have to remap those givs also. See
1893 find_splittable_regs. */
1896 splittable_regs[regno]
1897 = GEN_INT (INTVAL (giv_inc)
1898 + INTVAL (splittable_regs[src_regno]));
1899 giv_inc = splittable_regs[regno];
1901 /* Now split the induction variable by changing the dest
1902 of this insn to a new register, and setting its
1903 reg_map entry to point to this new register.
1905 If this is the last iteration, and this is the last insn
1906 that will update the iv, then reuse the original dest,
1907 to ensure that the iv will have the proper value when
1908 the loop exits or repeats.
1910 Using splittable_regs_updates here like this is safe,
1911 because it can only be greater than one if all
1912 instructions modifying the iv are always executed in
1915 if (! last_iteration
1916 || (splittable_regs_updates[regno]-- != 1))
1918 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1920 map->reg_map[regno] = tem;
1921 record_base_value (REGNO (tem),
1922 giv_inc == const0_rtx
1924 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1925 giv_src_reg, giv_inc),
1929 map->reg_map[regno] = giv_src_reg;
1932 /* The constant being added could be too large for an add
1933 immediate, so can't directly emit an insn here. */
1934 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1935 copy = get_last_insn ();
1936 pattern = PATTERN (copy);
1940 pattern = copy_rtx_and_substitute (pattern, map, 0);
1941 copy = emit_insn (pattern);
1943 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1946 /* If this insn is setting CC0, it may need to look at
1947 the insn that uses CC0 to see what type of insn it is.
1948 In that case, the call to recog via validate_change will
1949 fail. So don't substitute constants here. Instead,
1950 do it when we emit the following insn.
1952 For example, see the pyr.md file. That machine has signed and
1953 unsigned compares. The compare patterns must check the
1954 following branch insn to see which what kind of compare to
1957 If the previous insn set CC0, substitute constants on it as
1959 if (sets_cc0_p (PATTERN (copy)) != 0)
1964 try_constants (cc0_insn, map);
1966 try_constants (copy, map);
1969 try_constants (copy, map);
1972 /* Make split induction variable constants `permanent' since we
1973 know there are no backward branches across iteration variable
1974 settings which would invalidate this. */
1975 if (dest_reg_was_split)
1977 int regno = REGNO (SET_DEST (set));
1979 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
1980 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
1982 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
1987 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
1988 copy = emit_jump_insn (pattern);
1989 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1991 if (JUMP_LABEL (insn) == start_label && insn == copy_end
1992 && ! last_iteration)
1994 /* This is a branch to the beginning of the loop; this is the
1995 last insn being copied; and this is not the last iteration.
1996 In this case, we want to change the original fall through
1997 case to be a branch past the end of the loop, and the
1998 original jump label case to fall_through. */
2000 if (invert_exp (pattern, copy))
2002 if (! redirect_exp (&pattern,
2003 get_label_from_map (map,
2005 (JUMP_LABEL (insn))),
2012 rtx lab = gen_label_rtx ();
2013 /* Can't do it by reversing the jump (probably because we
2014 couldn't reverse the conditions), so emit a new
2015 jump_insn after COPY, and redirect the jump around
2017 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2018 jmp = emit_barrier_after (jmp);
2019 emit_label_after (lab, jmp);
2020 LABEL_NUSES (lab) = 0;
2021 if (! redirect_exp (&pattern,
2022 get_label_from_map (map,
2024 (JUMP_LABEL (insn))),
2032 try_constants (cc0_insn, map);
2035 try_constants (copy, map);
2037 /* Set the jump label of COPY correctly to avoid problems with
2038 later passes of unroll_loop, if INSN had jump label set. */
2039 if (JUMP_LABEL (insn))
2043 /* Can't use the label_map for every insn, since this may be
2044 the backward branch, and hence the label was not mapped. */
2045 if ((set = single_set (copy)))
2047 tem = SET_SRC (set);
2048 if (GET_CODE (tem) == LABEL_REF)
2049 label = XEXP (tem, 0);
2050 else if (GET_CODE (tem) == IF_THEN_ELSE)
2052 if (XEXP (tem, 1) != pc_rtx)
2053 label = XEXP (XEXP (tem, 1), 0);
2055 label = XEXP (XEXP (tem, 2), 0);
2059 if (label && GET_CODE (label) == CODE_LABEL)
2060 JUMP_LABEL (copy) = label;
2063 /* An unrecognizable jump insn, probably the entry jump
2064 for a switch statement. This label must have been mapped,
2065 so just use the label_map to get the new jump label. */
2067 = get_label_from_map (map,
2068 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2071 /* If this is a non-local jump, then must increase the label
2072 use count so that the label will not be deleted when the
2073 original jump is deleted. */
2074 LABEL_NUSES (JUMP_LABEL (copy))++;
2076 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2077 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2079 rtx pat = PATTERN (copy);
2080 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2081 int len = XVECLEN (pat, diff_vec_p);
2084 for (i = 0; i < len; i++)
2085 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2088 /* If this used to be a conditional jump insn but whose branch
2089 direction is now known, we must do something special. */
2090 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2093 /* If the previous insn set cc0 for us, delete it. */
2094 if (sets_cc0_p (PREV_INSN (copy)))
2095 delete_insn (PREV_INSN (copy));
2098 /* If this is now a no-op, delete it. */
2099 if (map->last_pc_value == pc_rtx)
2101 /* Don't let delete_insn delete the label referenced here,
2102 because we might possibly need it later for some other
2103 instruction in the loop. */
2104 if (JUMP_LABEL (copy))
2105 LABEL_NUSES (JUMP_LABEL (copy))++;
2107 if (JUMP_LABEL (copy))
2108 LABEL_NUSES (JUMP_LABEL (copy))--;
2112 /* Otherwise, this is unconditional jump so we must put a
2113 BARRIER after it. We could do some dead code elimination
2114 here, but jump.c will do it just as well. */
2120 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2121 copy = emit_call_insn (pattern);
2122 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2124 /* Because the USAGE information potentially contains objects other
2125 than hard registers, we need to copy it. */
2126 CALL_INSN_FUNCTION_USAGE (copy)
2127 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2132 try_constants (cc0_insn, map);
2135 try_constants (copy, map);
2137 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2138 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2139 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2143 /* If this is the loop start label, then we don't need to emit a
2144 copy of this label since no one will use it. */
2146 if (insn != start_label)
2148 copy = emit_label (get_label_from_map (map,
2149 CODE_LABEL_NUMBER (insn)));
2155 copy = emit_barrier ();
2159 /* VTOP and CONT notes are valid only before the loop exit test.
2160 If placed anywhere else, loop may generate bad code. */
2161 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2162 the associated rtl. We do not want to share the structure in
2165 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2166 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2167 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2168 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2169 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2170 copy = emit_note (NOTE_SOURCE_FILE (insn),
2171 NOTE_LINE_NUMBER (insn));
2180 map->insn_map[INSN_UID (insn)] = copy;
2182 while (insn != copy_end);
2184 /* Now finish coping the REG_NOTES. */
2188 insn = NEXT_INSN (insn);
2189 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2190 || GET_CODE (insn) == CALL_INSN)
2191 && map->insn_map[INSN_UID (insn)])
2192 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2194 while (insn != copy_end);
2196 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2197 each of these notes here, since there may be some important ones, such as
2198 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2199 iteration, because the original notes won't be deleted.
2201 We can't use insert_before here, because when from preconditioning,
2202 insert_before points before the loop. We can't use copy_end, because
2203 there may be insns already inserted after it (which we don't want to
2204 copy) when not from preconditioning code. */
2206 if (! last_iteration)
2208 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2210 /* VTOP notes are valid only before the loop exit test.
2211 If placed anywhere else, loop may generate bad code.
2212 There is no need to test for NOTE_INSN_LOOP_CONT notes
2213 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2214 instructions before the last insn in the loop, and if the
2215 end test is that short, there will be a VTOP note between
2216 the CONT note and the test. */
2217 if (GET_CODE (insn) == NOTE
2218 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2219 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2220 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2221 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2225 if (final_label && LABEL_NUSES (final_label) > 0)
2226 emit_label (final_label);
2228 tem = gen_sequence ();
2230 emit_insn_before (tem, insert_before);
2233 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2234 emitted. This will correctly handle the case where the increment value
2235 won't fit in the immediate field of a PLUS insns. */
2238 emit_unrolled_add (dest_reg, src_reg, increment)
2239 rtx dest_reg, src_reg, increment;
2243 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2244 dest_reg, 0, OPTAB_LIB_WIDEN);
2246 if (dest_reg != result)
2247 emit_move_insn (dest_reg, result);
2250 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2251 is a backward branch in that range that branches to somewhere between
2252 LOOP_START and INSN. Returns 0 otherwise. */
2254 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2255 In practice, this is not a problem, because this function is seldom called,
2256 and uses a negligible amount of CPU time on average. */
2259 back_branch_in_range_p (insn, loop_start, loop_end)
2261 rtx loop_start, loop_end;
2263 rtx p, q, target_insn;
2264 rtx orig_loop_end = loop_end;
2266 /* Stop before we get to the backward branch at the end of the loop. */
2267 loop_end = prev_nonnote_insn (loop_end);
2268 if (GET_CODE (loop_end) == BARRIER)
2269 loop_end = PREV_INSN (loop_end);
2271 /* Check in case insn has been deleted, search forward for first non
2272 deleted insn following it. */
2273 while (INSN_DELETED_P (insn))
2274 insn = NEXT_INSN (insn);
2276 /* Check for the case where insn is the last insn in the loop. Deal
2277 with the case where INSN was a deleted loop test insn, in which case
2278 it will now be the NOTE_LOOP_END. */
2279 if (insn == loop_end || insn == orig_loop_end)
2282 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2284 if (GET_CODE (p) == JUMP_INSN)
2286 target_insn = JUMP_LABEL (p);
2288 /* Search from loop_start to insn, to see if one of them is
2289 the target_insn. We can't use INSN_LUID comparisons here,
2290 since insn may not have an LUID entry. */
2291 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2292 if (q == target_insn)
2300 /* Try to generate the simplest rtx for the expression
2301 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2305 fold_rtx_mult_add (mult1, mult2, add1, mode)
2306 rtx mult1, mult2, add1;
2307 enum machine_mode mode;
2312 /* The modes must all be the same. This should always be true. For now,
2313 check to make sure. */
2314 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2315 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2316 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2319 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2320 will be a constant. */
2321 if (GET_CODE (mult1) == CONST_INT)
2328 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2330 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2332 /* Again, put the constant second. */
2333 if (GET_CODE (add1) == CONST_INT)
2340 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2342 result = gen_rtx_PLUS (mode, add1, mult_res);
2347 /* Searches the list of induction struct's for the biv BL, to try to calculate
2348 the total increment value for one iteration of the loop as a constant.
2350 Returns the increment value as an rtx, simplified as much as possible,
2351 if it can be calculated. Otherwise, returns 0. */
2354 biv_total_increment (bl, loop_start, loop_end)
2355 struct iv_class *bl;
2356 rtx loop_start, loop_end;
2358 struct induction *v;
2361 /* For increment, must check every instruction that sets it. Each
2362 instruction must be executed only once each time through the loop.
2363 To verify this, we check that the insn is always executed, and that
2364 there are no backward branches after the insn that branch to before it.
2365 Also, the insn must have a mult_val of one (to make sure it really is
2368 result = const0_rtx;
2369 for (v = bl->biv; v; v = v->next_iv)
2371 if (v->always_computable && v->mult_val == const1_rtx
2372 && ! v->maybe_multiple)
2373 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2381 /* Determine the initial value of the iteration variable, and the amount
2382 that it is incremented each loop. Use the tables constructed by
2383 the strength reduction pass to calculate these values.
2385 Initial_value and/or increment are set to zero if their values could not
2389 iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
2390 rtx iteration_var, *initial_value, *increment;
2391 rtx loop_start, loop_end;
2393 struct iv_class *bl;
2395 struct induction *v;
2398 /* Clear the result values, in case no answer can be found. */
2402 /* The iteration variable can be either a giv or a biv. Check to see
2403 which it is, and compute the variable's initial value, and increment
2404 value if possible. */
2406 /* If this is a new register, can't handle it since we don't have any
2407 reg_iv_type entry for it. */
2408 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
2410 if (loop_dump_stream)
2411 fprintf (loop_dump_stream,
2412 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2416 /* Reject iteration variables larger than the host wide int size, since they
2417 could result in a number of iterations greater than the range of our
2418 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2419 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2420 > HOST_BITS_PER_WIDE_INT))
2422 if (loop_dump_stream)
2423 fprintf (loop_dump_stream,
2424 "Loop unrolling: Iteration var rejected because mode too large.\n");
2427 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2429 if (loop_dump_stream)
2430 fprintf (loop_dump_stream,
2431 "Loop unrolling: Iteration var not an integer.\n");
2434 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2436 /* When reg_iv_type / reg_iv_info is resized for biv increments
2437 that are turned into givs, reg_biv_class is not resized.
2438 So check here that we don't make an out-of-bounds access. */
2439 if (REGNO (iteration_var) >= max_reg_before_loop)
2442 /* Grab initial value, only useful if it is a constant. */
2443 bl = reg_biv_class[REGNO (iteration_var)];
2444 *initial_value = bl->initial_value;
2446 *increment = biv_total_increment (bl, loop_start, loop_end);
2448 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2450 HOST_WIDE_INT offset = 0;
2451 struct induction *v = REG_IV_INFO (REGNO (iteration_var));
2453 if (REGNO (v->src_reg) >= max_reg_before_loop)
2456 bl = reg_biv_class[REGNO (v->src_reg)];
2458 /* Increment value is mult_val times the increment value of the biv. */
2460 *increment = biv_total_increment (bl, loop_start, loop_end);
2463 struct induction *biv_inc;
2466 = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, v->mode);
2467 /* The caller assumes that one full increment has occured at the
2468 first loop test. But that's not true when the biv is incremented
2469 after the giv is set (which is the usual case), e.g.:
2470 i = 6; do {;} while (i++ < 9) .
2471 Therefore, we bias the initial value by subtracting the amount of
2472 the increment that occurs between the giv set and the giv test. */
2473 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
2475 if (loop_insn_first_p (v->insn, biv_inc->insn))
2476 offset -= INTVAL (biv_inc->add_val);
2478 offset *= INTVAL (v->mult_val);
2480 if (loop_dump_stream)
2481 fprintf (loop_dump_stream,
2482 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2484 /* Initial value is mult_val times the biv's initial value plus
2485 add_val. Only useful if it is a constant. */
2487 = fold_rtx_mult_add (v->mult_val,
2488 plus_constant (bl->initial_value, offset),
2489 v->add_val, v->mode);
2493 if (loop_dump_stream)
2494 fprintf (loop_dump_stream,
2495 "Loop unrolling: Not basic or general induction var.\n");
2501 /* For each biv and giv, determine whether it can be safely split into
2502 a different variable for each unrolled copy of the loop body. If it
2503 is safe to split, then indicate that by saving some useful info
2504 in the splittable_regs array.
2506 If the loop is being completely unrolled, then splittable_regs will hold
2507 the current value of the induction variable while the loop is unrolled.
2508 It must be set to the initial value of the induction variable here.
2509 Otherwise, splittable_regs will hold the difference between the current
2510 value of the induction variable and the value the induction variable had
2511 at the top of the loop. It must be set to the value 0 here.
2513 Returns the total number of instructions that set registers that are
2516 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2517 constant values are unnecessary, since we can easily calculate increment
2518 values in this case even if nothing is constant. The increment value
2519 should not involve a multiply however. */
2521 /* ?? Even if the biv/giv increment values aren't constant, it may still
2522 be beneficial to split the variable if the loop is only unrolled a few
2523 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2526 find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
2527 unroll_number, n_iterations)
2528 enum unroll_types unroll_type;
2529 rtx loop_start, loop_end;
2530 rtx end_insert_before;
2532 unsigned HOST_WIDE_INT n_iterations;
2534 struct iv_class *bl;
2535 struct induction *v;
2537 rtx biv_final_value;
2541 for (bl = loop_iv_list; bl; bl = bl->next)
2543 /* Biv_total_increment must return a constant value,
2544 otherwise we can not calculate the split values. */
2546 increment = biv_total_increment (bl, loop_start, loop_end);
2547 if (! increment || GET_CODE (increment) != CONST_INT)
2550 /* The loop must be unrolled completely, or else have a known number
2551 of iterations and only one exit, or else the biv must be dead
2552 outside the loop, or else the final value must be known. Otherwise,
2553 it is unsafe to split the biv since it may not have the proper
2554 value on loop exit. */
2556 /* loop_number_exit_count is non-zero if the loop has an exit other than
2557 a fall through at the end. */
2560 biv_final_value = 0;
2561 if (unroll_type != UNROLL_COMPLETELY
2562 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2563 || unroll_type == UNROLL_NAIVE)
2564 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2566 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2567 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2568 < INSN_LUID (bl->init_insn))
2569 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2570 && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end,
2574 /* If any of the insns setting the BIV don't do so with a simple
2575 PLUS, we don't know how to split it. */
2576 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2577 if ((tem = single_set (v->insn)) == 0
2578 || GET_CODE (SET_DEST (tem)) != REG
2579 || REGNO (SET_DEST (tem)) != bl->regno
2580 || GET_CODE (SET_SRC (tem)) != PLUS)
2583 /* If final value is non-zero, then must emit an instruction which sets
2584 the value of the biv to the proper value. This is done after
2585 handling all of the givs, since some of them may need to use the
2586 biv's value in their initialization code. */
2588 /* This biv is splittable. If completely unrolling the loop, save
2589 the biv's initial value. Otherwise, save the constant zero. */
2591 if (biv_splittable == 1)
2593 if (unroll_type == UNROLL_COMPLETELY)
2595 /* If the initial value of the biv is itself (i.e. it is too
2596 complicated for strength_reduce to compute), or is a hard
2597 register, or it isn't invariant, then we must create a new
2598 pseudo reg to hold the initial value of the biv. */
2600 if (GET_CODE (bl->initial_value) == REG
2601 && (REGNO (bl->initial_value) == bl->regno
2602 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2603 || ! invariant_p (bl->initial_value)))
2605 rtx tem = gen_reg_rtx (bl->biv->mode);
2607 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2608 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2611 if (loop_dump_stream)
2612 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2613 bl->regno, REGNO (tem));
2615 splittable_regs[bl->regno] = tem;
2618 splittable_regs[bl->regno] = bl->initial_value;
2621 splittable_regs[bl->regno] = const0_rtx;
2623 /* Save the number of instructions that modify the biv, so that
2624 we can treat the last one specially. */
2626 splittable_regs_updates[bl->regno] = bl->biv_count;
2627 result += bl->biv_count;
2629 if (loop_dump_stream)
2630 fprintf (loop_dump_stream,
2631 "Biv %d safe to split.\n", bl->regno);
2634 /* Check every giv that depends on this biv to see whether it is
2635 splittable also. Even if the biv isn't splittable, givs which
2636 depend on it may be splittable if the biv is live outside the
2637 loop, and the givs aren't. */
2639 result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
2640 increment, unroll_number);
2642 /* If final value is non-zero, then must emit an instruction which sets
2643 the value of the biv to the proper value. This is done after
2644 handling all of the givs, since some of them may need to use the
2645 biv's value in their initialization code. */
2646 if (biv_final_value)
2648 /* If the loop has multiple exits, emit the insns before the
2649 loop to ensure that it will always be executed no matter
2650 how the loop exits. Otherwise emit the insn after the loop,
2651 since this is slightly more efficient. */
2652 if (! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
2653 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2658 /* Create a new register to hold the value of the biv, and then
2659 set the biv to its final value before the loop start. The biv
2660 is set to its final value before loop start to ensure that
2661 this insn will always be executed, no matter how the loop
2663 rtx tem = gen_reg_rtx (bl->biv->mode);
2664 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2666 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2668 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2672 if (loop_dump_stream)
2673 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2674 REGNO (bl->biv->src_reg), REGNO (tem));
2676 /* Set up the mapping from the original biv register to the new
2678 bl->biv->src_reg = tem;
2685 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2686 for the instruction that is using it. Do not make any changes to that
2690 verify_addresses (v, giv_inc, unroll_number)
2691 struct induction *v;
2696 rtx orig_addr = *v->location;
2697 rtx last_addr = plus_constant (v->dest_reg,
2698 INTVAL (giv_inc) * (unroll_number - 1));
2700 /* First check to see if either address would fail. Handle the fact
2701 that we have may have a match_dup. */
2702 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2703 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2706 /* Now put things back the way they were before. This should always
2708 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2714 /* For every giv based on the biv BL, check to determine whether it is
2715 splittable. This is a subroutine to find_splittable_regs ().
2717 Return the number of instructions that set splittable registers. */
2720 find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
2722 struct iv_class *bl;
2723 enum unroll_types unroll_type;
2724 rtx loop_start, loop_end;
2728 struct induction *v, *v2;
2733 /* Scan the list of givs, and set the same_insn field when there are
2734 multiple identical givs in the same insn. */
2735 for (v = bl->giv; v; v = v->next_iv)
2736 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2737 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2741 for (v = bl->giv; v; v = v->next_iv)
2745 /* Only split the giv if it has already been reduced, or if the loop is
2746 being completely unrolled. */
2747 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2750 /* The giv can be split if the insn that sets the giv is executed once
2751 and only once on every iteration of the loop. */
2752 /* An address giv can always be split. v->insn is just a use not a set,
2753 and hence it does not matter whether it is always executed. All that
2754 matters is that all the biv increments are always executed, and we
2755 won't reach here if they aren't. */
2756 if (v->giv_type != DEST_ADDR
2757 && (! v->always_computable
2758 || back_branch_in_range_p (v->insn, loop_start, loop_end)))
2761 /* The giv increment value must be a constant. */
2762 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2764 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2767 /* The loop must be unrolled completely, or else have a known number of
2768 iterations and only one exit, or else the giv must be dead outside
2769 the loop, or else the final value of the giv must be known.
2770 Otherwise, it is not safe to split the giv since it may not have the
2771 proper value on loop exit. */
2773 /* The used outside loop test will fail for DEST_ADDR givs. They are
2774 never used outside the loop anyways, so it is always safe to split a
2778 if (unroll_type != UNROLL_COMPLETELY
2779 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2780 || unroll_type == UNROLL_NAIVE)
2781 && v->giv_type != DEST_ADDR
2782 /* The next part is true if the pseudo is used outside the loop.
2783 We assume that this is true for any pseudo created after loop
2784 starts, because we don't have a reg_n_info entry for them. */
2785 && (REGNO (v->dest_reg) >= max_reg_before_loop
2786 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2787 /* Check for the case where the pseudo is set by a shift/add
2788 sequence, in which case the first insn setting the pseudo
2789 is the first insn of the shift/add sequence. */
2790 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2791 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2792 != INSN_UID (XEXP (tem, 0)))))
2793 /* Line above always fails if INSN was moved by loop opt. */
2794 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2795 >= INSN_LUID (loop_end)))
2796 /* Givs made from biv increments are missed by the above test, so
2797 test explicitly for them. */
2798 && (REGNO (v->dest_reg) < first_increment_giv
2799 || REGNO (v->dest_reg) > last_increment_giv)
2800 && ! (final_value = v->final_value))
2804 /* Currently, non-reduced/final-value givs are never split. */
2805 /* Should emit insns after the loop if possible, as the biv final value
2808 /* If the final value is non-zero, and the giv has not been reduced,
2809 then must emit an instruction to set the final value. */
2810 if (final_value && !v->new_reg)
2812 /* Create a new register to hold the value of the giv, and then set
2813 the giv to its final value before the loop start. The giv is set
2814 to its final value before loop start to ensure that this insn
2815 will always be executed, no matter how we exit. */
2816 tem = gen_reg_rtx (v->mode);
2817 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2818 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2821 if (loop_dump_stream)
2822 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2823 REGNO (v->dest_reg), REGNO (tem));
2829 /* This giv is splittable. If completely unrolling the loop, save the
2830 giv's initial value. Otherwise, save the constant zero for it. */
2832 if (unroll_type == UNROLL_COMPLETELY)
2834 /* It is not safe to use bl->initial_value here, because it may not
2835 be invariant. It is safe to use the initial value stored in
2836 the splittable_regs array if it is set. In rare cases, it won't
2837 be set, so then we do exactly the same thing as
2838 find_splittable_regs does to get a safe value. */
2839 rtx biv_initial_value;
2841 if (splittable_regs[bl->regno])
2842 biv_initial_value = splittable_regs[bl->regno];
2843 else if (GET_CODE (bl->initial_value) != REG
2844 || (REGNO (bl->initial_value) != bl->regno
2845 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2846 biv_initial_value = bl->initial_value;
2849 rtx tem = gen_reg_rtx (bl->biv->mode);
2851 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2852 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2854 biv_initial_value = tem;
2856 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2857 v->add_val, v->mode);
2864 /* If a giv was combined with another giv, then we can only split
2865 this giv if the giv it was combined with was reduced. This
2866 is because the value of v->new_reg is meaningless in this
2868 if (v->same && ! v->same->new_reg)
2870 if (loop_dump_stream)
2871 fprintf (loop_dump_stream,
2872 "giv combined with unreduced giv not split.\n");
2875 /* If the giv is an address destination, it could be something other
2876 than a simple register, these have to be treated differently. */
2877 else if (v->giv_type == DEST_REG)
2879 /* If value is not a constant, register, or register plus
2880 constant, then compute its value into a register before
2881 loop start. This prevents invalid rtx sharing, and should
2882 generate better code. We can use bl->initial_value here
2883 instead of splittable_regs[bl->regno] because this code
2884 is going before the loop start. */
2885 if (unroll_type == UNROLL_COMPLETELY
2886 && GET_CODE (value) != CONST_INT
2887 && GET_CODE (value) != REG
2888 && (GET_CODE (value) != PLUS
2889 || GET_CODE (XEXP (value, 0)) != REG
2890 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2892 rtx tem = gen_reg_rtx (v->mode);
2893 record_base_value (REGNO (tem), v->add_val, 0);
2894 emit_iv_add_mult (bl->initial_value, v->mult_val,
2895 v->add_val, tem, loop_start);
2899 splittable_regs[REGNO (v->new_reg)] = value;
2900 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2904 /* Splitting address givs is useful since it will often allow us
2905 to eliminate some increment insns for the base giv as
2908 /* If the addr giv is combined with a dest_reg giv, then all
2909 references to that dest reg will be remapped, which is NOT
2910 what we want for split addr regs. We always create a new
2911 register for the split addr giv, just to be safe. */
2913 /* If we have multiple identical address givs within a
2914 single instruction, then use a single pseudo reg for
2915 both. This is necessary in case one is a match_dup
2918 v->const_adjust = 0;
2922 v->dest_reg = v->same_insn->dest_reg;
2923 if (loop_dump_stream)
2924 fprintf (loop_dump_stream,
2925 "Sharing address givs in insn %d\n",
2926 INSN_UID (v->insn));
2928 /* If multiple address GIVs have been combined with the
2929 same dest_reg GIV, do not create a new register for
2931 else if (unroll_type != UNROLL_COMPLETELY
2932 && v->giv_type == DEST_ADDR
2933 && v->same && v->same->giv_type == DEST_ADDR
2934 && v->same->unrolled
2935 /* combine_givs_p may return true for some cases
2936 where the add and mult values are not equal.
2937 To share a register here, the values must be
2939 && rtx_equal_p (v->same->mult_val, v->mult_val)
2940 && rtx_equal_p (v->same->add_val, v->add_val)
2941 /* If the memory references have different modes,
2942 then the address may not be valid and we must
2943 not share registers. */
2944 && verify_addresses (v, giv_inc, unroll_number))
2946 v->dest_reg = v->same->dest_reg;
2949 else if (unroll_type != UNROLL_COMPLETELY)
2951 /* If not completely unrolling the loop, then create a new
2952 register to hold the split value of the DEST_ADDR giv.
2953 Emit insn to initialize its value before loop start. */
2955 rtx tem = gen_reg_rtx (v->mode);
2956 struct induction *same = v->same;
2957 rtx new_reg = v->new_reg;
2958 record_base_value (REGNO (tem), v->add_val, 0);
2960 if (same && same->derived_from)
2962 /* calculate_giv_inc doesn't work for derived givs.
2963 copy_loop_body works around the problem for the
2964 DEST_REG givs themselves, but it can't handle
2965 DEST_ADDR givs that have been combined with
2966 a derived DEST_REG giv.
2967 So Handle V as if the giv from which V->SAME has
2968 been derived has been combined with V.
2969 recombine_givs only derives givs from givs that
2970 are reduced the ordinary, so we need not worry
2971 about same->derived_from being in turn derived. */
2973 same = same->derived_from;
2974 new_reg = express_from (same, v);
2975 new_reg = replace_rtx (new_reg, same->dest_reg,
2979 /* If the address giv has a constant in its new_reg value,
2980 then this constant can be pulled out and put in value,
2981 instead of being part of the initialization code. */
2983 if (GET_CODE (new_reg) == PLUS
2984 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
2987 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
2989 /* Only succeed if this will give valid addresses.
2990 Try to validate both the first and the last
2991 address resulting from loop unrolling, if
2992 one fails, then can't do const elim here. */
2993 if (verify_addresses (v, giv_inc, unroll_number))
2995 /* Save the negative of the eliminated const, so
2996 that we can calculate the dest_reg's increment
2998 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
3000 new_reg = XEXP (new_reg, 0);
3001 if (loop_dump_stream)
3002 fprintf (loop_dump_stream,
3003 "Eliminating constant from giv %d\n",
3012 /* If the address hasn't been checked for validity yet, do so
3013 now, and fail completely if either the first or the last
3014 unrolled copy of the address is not a valid address
3015 for the instruction that uses it. */
3016 if (v->dest_reg == tem
3017 && ! verify_addresses (v, giv_inc, unroll_number))
3019 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3020 if (v2->same_insn == v)
3023 if (loop_dump_stream)
3024 fprintf (loop_dump_stream,
3025 "Invalid address for giv at insn %d\n",
3026 INSN_UID (v->insn));
3030 v->new_reg = new_reg;
3033 /* We set this after the address check, to guarantee that
3034 the register will be initialized. */
3037 /* To initialize the new register, just move the value of
3038 new_reg into it. This is not guaranteed to give a valid
3039 instruction on machines with complex addressing modes.
3040 If we can't recognize it, then delete it and emit insns
3041 to calculate the value from scratch. */
3042 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
3043 copy_rtx (v->new_reg)),
3045 if (recog_memoized (PREV_INSN (loop_start)) < 0)
3049 /* We can't use bl->initial_value to compute the initial
3050 value, because the loop may have been preconditioned.
3051 We must calculate it from NEW_REG. Try using
3052 force_operand instead of emit_iv_add_mult. */
3053 delete_insn (PREV_INSN (loop_start));
3056 ret = force_operand (v->new_reg, tem);
3058 emit_move_insn (tem, ret);
3059 sequence = gen_sequence ();
3061 emit_insn_before (sequence, loop_start);
3063 if (loop_dump_stream)
3064 fprintf (loop_dump_stream,
3065 "Invalid init insn, rewritten.\n");
3070 v->dest_reg = value;
3072 /* Check the resulting address for validity, and fail
3073 if the resulting address would be invalid. */
3074 if (! verify_addresses (v, giv_inc, unroll_number))
3076 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3077 if (v2->same_insn == v)
3080 if (loop_dump_stream)
3081 fprintf (loop_dump_stream,
3082 "Invalid address for giv at insn %d\n",
3083 INSN_UID (v->insn));
3086 if (v->same && v->same->derived_from)
3088 /* Handle V as if the giv from which V->SAME has
3089 been derived has been combined with V. */
3091 v->same = v->same->derived_from;
3092 v->new_reg = express_from (v->same, v);
3093 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3099 /* Store the value of dest_reg into the insn. This sharing
3100 will not be a problem as this insn will always be copied
3103 *v->location = v->dest_reg;
3105 /* If this address giv is combined with a dest reg giv, then
3106 save the base giv's induction pointer so that we will be
3107 able to handle this address giv properly. The base giv
3108 itself does not have to be splittable. */
3110 if (v->same && v->same->giv_type == DEST_REG)
3111 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3113 if (GET_CODE (v->new_reg) == REG)
3115 /* This giv maybe hasn't been combined with any others.
3116 Make sure that it's giv is marked as splittable here. */
3118 splittable_regs[REGNO (v->new_reg)] = value;
3119 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3121 /* Make it appear to depend upon itself, so that the
3122 giv will be properly split in the main loop above. */
3126 addr_combined_regs[REGNO (v->new_reg)] = v;
3130 if (loop_dump_stream)
3131 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3137 /* Currently, unreduced giv's can't be split. This is not too much
3138 of a problem since unreduced giv's are not live across loop
3139 iterations anyways. When unrolling a loop completely though,
3140 it makes sense to reduce&split givs when possible, as this will
3141 result in simpler instructions, and will not require that a reg
3142 be live across loop iterations. */
3144 splittable_regs[REGNO (v->dest_reg)] = value;
3145 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3146 REGNO (v->dest_reg), INSN_UID (v->insn));
3152 /* Unreduced givs are only updated once by definition. Reduced givs
3153 are updated as many times as their biv is. Mark it so if this is
3154 a splittable register. Don't need to do anything for address givs
3155 where this may not be a register. */
3157 if (GET_CODE (v->new_reg) == REG)
3161 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3163 if (count > 1 && v->derived_from)
3164 /* In this case, there is one set where the giv insn was and one
3165 set each after each biv increment. (Most are likely dead.) */
3168 splittable_regs_updates[REGNO (v->new_reg)] = count;
3173 if (loop_dump_stream)
3177 if (GET_CODE (v->dest_reg) == CONST_INT)
3179 else if (GET_CODE (v->dest_reg) != REG)
3180 regnum = REGNO (XEXP (v->dest_reg, 0));
3182 regnum = REGNO (v->dest_reg);
3183 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3184 regnum, INSN_UID (v->insn));
3191 /* Try to prove that the register is dead after the loop exits. Trace every
3192 loop exit looking for an insn that will always be executed, which sets
3193 the register to some value, and appears before the first use of the register
3194 is found. If successful, then return 1, otherwise return 0. */
3196 /* ?? Could be made more intelligent in the handling of jumps, so that
3197 it can search past if statements and other similar structures. */
3200 reg_dead_after_loop (reg, loop_start, loop_end)
3201 rtx reg, loop_start, loop_end;
3206 int label_count = 0;
3207 int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
3209 /* In addition to checking all exits of this loop, we must also check
3210 all exits of inner nested loops that would exit this loop. We don't
3211 have any way to identify those, so we just give up if there are any
3212 such inner loop exits. */
3214 for (label = loop_number_exit_labels[this_loop_num]; label;
3215 label = LABEL_NEXTREF (label))
3218 if (label_count != loop_number_exit_count[this_loop_num])
3221 /* HACK: Must also search the loop fall through exit, create a label_ref
3222 here which points to the loop_end, and append the loop_number_exit_labels
3224 label = gen_rtx_LABEL_REF (VOIDmode, loop_end);
3225 LABEL_NEXTREF (label) = loop_number_exit_labels[this_loop_num];
3227 for ( ; label; label = LABEL_NEXTREF (label))
3229 /* Succeed if find an insn which sets the biv or if reach end of
3230 function. Fail if find an insn that uses the biv, or if come to
3231 a conditional jump. */
3233 insn = NEXT_INSN (XEXP (label, 0));
3236 code = GET_CODE (insn);
3237 if (GET_RTX_CLASS (code) == 'i')
3241 if (reg_referenced_p (reg, PATTERN (insn)))
3244 set = single_set (insn);
3245 if (set && rtx_equal_p (SET_DEST (set), reg))
3249 if (code == JUMP_INSN)
3251 if (GET_CODE (PATTERN (insn)) == RETURN)
3253 else if (! simplejump_p (insn)
3254 /* Prevent infinite loop following infinite loops. */
3255 || jump_count++ > 20)
3258 insn = JUMP_LABEL (insn);
3261 insn = NEXT_INSN (insn);
3265 /* Success, the register is dead on all loop exits. */
3269 /* Try to calculate the final value of the biv, the value it will have at
3270 the end of the loop. If we can do it, return that value. */
3273 final_biv_value (bl, loop_start, loop_end, n_iterations)
3274 struct iv_class *bl;
3275 rtx loop_start, loop_end;
3276 unsigned HOST_WIDE_INT n_iterations;
3280 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3282 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3285 /* The final value for reversed bivs must be calculated differently than
3286 for ordinary bivs. In this case, there is already an insn after the
3287 loop which sets this biv's final value (if necessary), and there are
3288 no other loop exits, so we can return any value. */
3291 if (loop_dump_stream)
3292 fprintf (loop_dump_stream,
3293 "Final biv value for %d, reversed biv.\n", bl->regno);
3298 /* Try to calculate the final value as initial value + (number of iterations
3299 * increment). For this to work, increment must be invariant, the only
3300 exit from the loop must be the fall through at the bottom (otherwise
3301 it may not have its final value when the loop exits), and the initial
3302 value of the biv must be invariant. */
3304 if (n_iterations != 0
3305 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
3306 && invariant_p (bl->initial_value))
3308 increment = biv_total_increment (bl, loop_start, loop_end);
3310 if (increment && invariant_p (increment))
3312 /* Can calculate the loop exit value, emit insns after loop
3313 end to calculate this value into a temporary register in
3314 case it is needed later. */
3316 tem = gen_reg_rtx (bl->biv->mode);
3317 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3318 /* Make sure loop_end is not the last insn. */
3319 if (NEXT_INSN (loop_end) == 0)
3320 emit_note_after (NOTE_INSN_DELETED, loop_end);
3321 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3322 bl->initial_value, tem, NEXT_INSN (loop_end));
3324 if (loop_dump_stream)
3325 fprintf (loop_dump_stream,
3326 "Final biv value for %d, calculated.\n", bl->regno);
3332 /* Check to see if the biv is dead at all loop exits. */
3333 if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
3335 if (loop_dump_stream)
3336 fprintf (loop_dump_stream,
3337 "Final biv value for %d, biv dead after loop exit.\n",
3346 /* Try to calculate the final value of the giv, the value it will have at
3347 the end of the loop. If we can do it, return that value. */
3350 final_giv_value (v, loop_start, loop_end, n_iterations)
3351 struct induction *v;
3352 rtx loop_start, loop_end;
3353 unsigned HOST_WIDE_INT n_iterations;
3355 struct iv_class *bl;
3358 rtx insert_before, seq;
3360 bl = reg_biv_class[REGNO (v->src_reg)];
3362 /* The final value for givs which depend on reversed bivs must be calculated
3363 differently than for ordinary givs. In this case, there is already an
3364 insn after the loop which sets this giv's final value (if necessary),
3365 and there are no other loop exits, so we can return any value. */
3368 if (loop_dump_stream)
3369 fprintf (loop_dump_stream,
3370 "Final giv value for %d, depends on reversed biv\n",
3371 REGNO (v->dest_reg));
3375 /* Try to calculate the final value as a function of the biv it depends
3376 upon. The only exit from the loop must be the fall through at the bottom
3377 (otherwise it may not have its final value when the loop exits). */
3379 /* ??? Can calculate the final giv value by subtracting off the
3380 extra biv increments times the giv's mult_val. The loop must have
3381 only one exit for this to work, but the loop iterations does not need
3384 if (n_iterations != 0
3385 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
3387 /* ?? It is tempting to use the biv's value here since these insns will
3388 be put after the loop, and hence the biv will have its final value
3389 then. However, this fails if the biv is subsequently eliminated.
3390 Perhaps determine whether biv's are eliminable before trying to
3391 determine whether giv's are replaceable so that we can use the
3392 biv value here if it is not eliminable. */
3394 /* We are emitting code after the end of the loop, so we must make
3395 sure that bl->initial_value is still valid then. It will still
3396 be valid if it is invariant. */
3398 increment = biv_total_increment (bl, loop_start, loop_end);
3400 if (increment && invariant_p (increment)
3401 && invariant_p (bl->initial_value))
3403 /* Can calculate the loop exit value of its biv as
3404 (n_iterations * increment) + initial_value */
3406 /* The loop exit value of the giv is then
3407 (final_biv_value - extra increments) * mult_val + add_val.
3408 The extra increments are any increments to the biv which
3409 occur in the loop after the giv's value is calculated.
3410 We must search from the insn that sets the giv to the end
3411 of the loop to calculate this value. */
3413 insert_before = NEXT_INSN (loop_end);
3415 /* Put the final biv value in tem. */
3416 tem = gen_reg_rtx (bl->biv->mode);
3417 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3418 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3419 bl->initial_value, tem, insert_before);
3421 /* Subtract off extra increments as we find them. */
3422 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3423 insn = NEXT_INSN (insn))
3425 struct induction *biv;
3427 for (biv = bl->biv; biv; biv = biv->next_iv)
3428 if (biv->insn == insn)
3431 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3432 biv->add_val, NULL_RTX, 0,
3434 seq = gen_sequence ();
3436 emit_insn_before (seq, insert_before);
3440 /* Now calculate the giv's final value. */
3441 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3444 if (loop_dump_stream)
3445 fprintf (loop_dump_stream,
3446 "Final giv value for %d, calc from biv's value.\n",
3447 REGNO (v->dest_reg));
3453 /* Replaceable giv's should never reach here. */
3457 /* Check to see if the biv is dead at all loop exits. */
3458 if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
3460 if (loop_dump_stream)
3461 fprintf (loop_dump_stream,
3462 "Final giv value for %d, giv dead after loop exit.\n",
3463 REGNO (v->dest_reg));
3472 /* Look back before LOOP_START for then insn that sets REG and return
3473 the equivalent constant if there is a REG_EQUAL note otherwise just
3474 the SET_SRC of REG. */
3477 loop_find_equiv_value (loop_start, reg)
3485 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3487 if (GET_CODE (insn) == CODE_LABEL)
3490 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3491 && reg_set_p (reg, insn))
3493 /* We found the last insn before the loop that sets the register.
3494 If it sets the entire register, and has a REG_EQUAL note,
3495 then use the value of the REG_EQUAL note. */
3496 if ((set = single_set (insn))
3497 && (SET_DEST (set) == reg))
3499 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3501 /* Only use the REG_EQUAL note if it is a constant.
3502 Other things, divide in particular, will cause
3503 problems later if we use them. */
3504 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3505 && CONSTANT_P (XEXP (note, 0)))
3506 ret = XEXP (note, 0);
3508 ret = SET_SRC (set);
3516 /* Return a simplified rtx for the expression OP - REG.
3518 REG must appear in OP, and OP must be a register or the sum of a register
3521 Thus, the return value must be const0_rtx or the second term.
3523 The caller is responsible for verifying that REG appears in OP and OP has
3527 subtract_reg_term (op, reg)
3532 if (GET_CODE (op) == PLUS)
3534 if (XEXP (op, 0) == reg)
3535 return XEXP (op, 1);
3536 else if (XEXP (op, 1) == reg)
3537 return XEXP (op, 0);
3539 /* OP does not contain REG as a term. */
3544 /* Find and return register term common to both expressions OP0 and
3545 OP1 or NULL_RTX if no such term exists. Each expression must be a
3546 REG or a PLUS of a REG. */
3549 find_common_reg_term (op0, op1)
3552 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3553 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3560 if (GET_CODE (op0) == PLUS)
3561 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3563 op01 = const0_rtx, op00 = op0;
3565 if (GET_CODE (op1) == PLUS)
3566 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3568 op11 = const0_rtx, op10 = op1;
3570 /* Find and return common register term if present. */
3571 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3573 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3577 /* No common register term found. */
3581 /* Calculate the number of loop iterations. Returns the exact number of loop
3582 iterations if it can be calculated, otherwise returns zero. */
3584 unsigned HOST_WIDE_INT
3585 loop_iterations (loop_start, loop_end, loop_info)
3586 rtx loop_start, loop_end;
3587 struct loop_info *loop_info;
3589 rtx comparison, comparison_value;
3590 rtx iteration_var, initial_value, increment, final_value;
3591 enum rtx_code comparison_code;
3592 HOST_WIDE_INT abs_inc;
3593 unsigned HOST_WIDE_INT abs_diff;
3596 int unsigned_p, compare_dir, final_larger;
3600 loop_info->n_iterations = 0;
3601 loop_info->initial_value = 0;
3602 loop_info->initial_equiv_value = 0;
3603 loop_info->comparison_value = 0;
3604 loop_info->final_value = 0;
3605 loop_info->final_equiv_value = 0;
3606 loop_info->increment = 0;
3607 loop_info->iteration_var = 0;
3608 loop_info->unroll_number = 1;
3610 /* We used to use prev_nonnote_insn here, but that fails because it might
3611 accidentally get the branch for a contained loop if the branch for this
3612 loop was deleted. We can only trust branches immediately before the
3614 last_loop_insn = PREV_INSN (loop_end);
3616 /* ??? We should probably try harder to find the jump insn
3617 at the end of the loop. The following code assumes that
3618 the last loop insn is a jump to the top of the loop. */
3619 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3621 if (loop_dump_stream)
3622 fprintf (loop_dump_stream,
3623 "Loop iterations: No final conditional branch found.\n");
3627 /* If there is a more than a single jump to the top of the loop
3628 we cannot (easily) determine the iteration count. */
3629 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3631 if (loop_dump_stream)
3632 fprintf (loop_dump_stream,
3633 "Loop iterations: Loop has multiple back edges.\n");
3637 /* Find the iteration variable. If the last insn is a conditional
3638 branch, and the insn before tests a register value, make that the
3639 iteration variable. */
3641 comparison = get_condition_for_loop (last_loop_insn);
3642 if (comparison == 0)
3644 if (loop_dump_stream)
3645 fprintf (loop_dump_stream,
3646 "Loop iterations: No final comparison found.\n");
3650 /* ??? Get_condition may switch position of induction variable and
3651 invariant register when it canonicalizes the comparison. */
3653 comparison_code = GET_CODE (comparison);
3654 iteration_var = XEXP (comparison, 0);
3655 comparison_value = XEXP (comparison, 1);
3657 if (GET_CODE (iteration_var) != REG)
3659 if (loop_dump_stream)
3660 fprintf (loop_dump_stream,
3661 "Loop iterations: Comparison not against register.\n");
3665 /* The only new registers that care created before loop iterations are
3666 givs made from biv increments, so this should never occur. */
3668 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
3671 iteration_info (iteration_var, &initial_value, &increment,
3672 loop_start, loop_end);
3673 if (initial_value == 0)
3674 /* iteration_info already printed a message. */
3679 switch (comparison_code)
3694 /* Cannot determine loop iterations with this case. */
3713 /* If the comparison value is an invariant register, then try to find
3714 its value from the insns before the start of the loop. */
3716 final_value = comparison_value;
3717 if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
3719 final_value = loop_find_equiv_value (loop_start, comparison_value);
3720 /* If we don't get an invariant final value, we are better
3721 off with the original register. */
3722 if (!invariant_p (final_value))
3723 final_value = comparison_value;
3726 /* Calculate the approximate final value of the induction variable
3727 (on the last successful iteration). The exact final value
3728 depends on the branch operator, and increment sign. It will be
3729 wrong if the iteration variable is not incremented by one each
3730 time through the loop and (comparison_value + off_by_one -
3731 initial_value) % increment != 0.
3732 ??? Note that the final_value may overflow and thus final_larger
3733 will be bogus. A potentially infinite loop will be classified
3734 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3736 final_value = plus_constant (final_value, off_by_one);
3738 /* Save the calculated values describing this loop's bounds, in case
3739 precondition_loop_p will need them later. These values can not be
3740 recalculated inside precondition_loop_p because strength reduction
3741 optimizations may obscure the loop's structure.
3743 These values are only required by precondition_loop_p and insert_bct
3744 whenever the number of iterations cannot be computed at compile time.
3745 Only the difference between final_value and initial_value is
3746 important. Note that final_value is only approximate. */
3747 loop_info->initial_value = initial_value;
3748 loop_info->comparison_value = comparison_value;
3749 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3750 loop_info->increment = increment;
3751 loop_info->iteration_var = iteration_var;
3752 loop_info->comparison_code = comparison_code;
3754 /* Try to determine the iteration count for loops such
3755 as (for i = init; i < init + const; i++). When running the
3756 loop optimization twice, the first pass often converts simple
3757 loops into this form. */
3759 if (REG_P (initial_value))
3765 reg1 = initial_value;
3766 if (GET_CODE (final_value) == PLUS)
3767 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3769 reg2 = final_value, const2 = const0_rtx;
3771 /* Check for initial_value = reg1, final_value = reg2 + const2,
3772 where reg1 != reg2. */
3773 if (REG_P (reg2) && reg2 != reg1)
3777 /* Find what reg1 is equivalent to. Hopefully it will
3778 either be reg2 or reg2 plus a constant. */
3779 temp = loop_find_equiv_value (loop_start, reg1);
3780 if (find_common_reg_term (temp, reg2))
3781 initial_value = temp;
3784 /* Find what reg2 is equivalent to. Hopefully it will
3785 either be reg1 or reg1 plus a constant. Let's ignore
3786 the latter case for now since it is not so common. */
3787 temp = loop_find_equiv_value (loop_start, reg2);
3788 if (temp == loop_info->iteration_var)
3789 temp = initial_value;
3791 final_value = (const2 == const0_rtx)
3792 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3795 else if (loop_info->vtop && GET_CODE (reg2) == CONST_INT)
3799 /* When running the loop optimizer twice, check_dbra_loop
3800 further obfuscates reversible loops of the form:
3801 for (i = init; i < init + const; i++). We often end up with
3802 final_value = 0, initial_value = temp, temp = temp2 - init,
3803 where temp2 = init + const. If the loop has a vtop we
3804 can replace initial_value with const. */
3806 temp = loop_find_equiv_value (loop_start, reg1);
3807 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3809 rtx temp2 = loop_find_equiv_value (loop_start, XEXP (temp, 0));
3810 if (GET_CODE (temp2) == PLUS
3811 && XEXP (temp2, 0) == XEXP (temp, 1))
3812 initial_value = XEXP (temp2, 1);
3817 /* If have initial_value = reg + const1 and final_value = reg +
3818 const2, then replace initial_value with const1 and final_value
3819 with const2. This should be safe since we are protected by the
3820 initial comparison before entering the loop if we have a vtop.
3821 For example, a + b < a + c is not equivalent to b < c for all a
3822 when using modulo arithmetic.
3824 ??? Without a vtop we could still perform the optimization if we check
3825 the initial and final values carefully. */
3827 && (reg_term = find_common_reg_term (initial_value, final_value)))
3829 initial_value = subtract_reg_term (initial_value, reg_term);
3830 final_value = subtract_reg_term (final_value, reg_term);
3833 loop_info->initial_equiv_value = initial_value;
3834 loop_info->final_equiv_value = final_value;
3836 /* For EQ comparison loops, we don't have a valid final value.
3837 Check this now so that we won't leave an invalid value if we
3838 return early for any other reason. */
3839 if (comparison_code == EQ)
3840 loop_info->final_equiv_value = loop_info->final_value = 0;
3844 if (loop_dump_stream)
3845 fprintf (loop_dump_stream,
3846 "Loop iterations: Increment value can't be calculated.\n");
3850 if (GET_CODE (increment) != CONST_INT)
3852 /* If we have a REG, check to see if REG holds a constant value. */
3853 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3854 clear if it is worthwhile to try to handle such RTL. */
3855 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3856 increment = loop_find_equiv_value (loop_start, increment);
3858 if (GET_CODE (increment) != CONST_INT)
3860 if (loop_dump_stream)
3862 fprintf (loop_dump_stream,
3863 "Loop iterations: Increment value not constant ");
3864 print_rtl (loop_dump_stream, increment);
3865 fprintf (loop_dump_stream, ".\n");
3869 loop_info->increment = increment;
3872 if (GET_CODE (initial_value) != CONST_INT)
3874 if (loop_dump_stream)
3876 fprintf (loop_dump_stream,
3877 "Loop iterations: Initial value not constant ");
3878 print_rtl (loop_dump_stream, initial_value);
3879 fprintf (loop_dump_stream, ".\n");
3883 else if (comparison_code == EQ)
3885 if (loop_dump_stream)
3886 fprintf (loop_dump_stream,
3887 "Loop iterations: EQ comparison loop.\n");
3890 else if (GET_CODE (final_value) != CONST_INT)
3892 if (loop_dump_stream)
3894 fprintf (loop_dump_stream,
3895 "Loop iterations: Final value not constant ");
3896 print_rtl (loop_dump_stream, final_value);
3897 fprintf (loop_dump_stream, ".\n");
3902 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3905 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3906 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3907 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3908 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3910 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3911 - (INTVAL (final_value) < INTVAL (initial_value));
3913 if (INTVAL (increment) > 0)
3915 else if (INTVAL (increment) == 0)
3920 /* There are 27 different cases: compare_dir = -1, 0, 1;
3921 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3922 There are 4 normal cases, 4 reverse cases (where the iteration variable
3923 will overflow before the loop exits), 4 infinite loop cases, and 15
3924 immediate exit (0 or 1 iteration depending on loop type) cases.
3925 Only try to optimize the normal cases. */
3927 /* (compare_dir/final_larger/increment_dir)
3928 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3929 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3930 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3931 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3933 /* ?? If the meaning of reverse loops (where the iteration variable
3934 will overflow before the loop exits) is undefined, then could
3935 eliminate all of these special checks, and just always assume
3936 the loops are normal/immediate/infinite. Note that this means
3937 the sign of increment_dir does not have to be known. Also,
3938 since it does not really hurt if immediate exit loops or infinite loops
3939 are optimized, then that case could be ignored also, and hence all
3940 loops can be optimized.
3942 According to ANSI Spec, the reverse loop case result is undefined,
3943 because the action on overflow is undefined.
3945 See also the special test for NE loops below. */
3947 if (final_larger == increment_dir && final_larger != 0
3948 && (final_larger == compare_dir || compare_dir == 0))
3953 if (loop_dump_stream)
3954 fprintf (loop_dump_stream,
3955 "Loop iterations: Not normal loop.\n");
3959 /* Calculate the number of iterations, final_value is only an approximation,
3960 so correct for that. Note that abs_diff and n_iterations are
3961 unsigned, because they can be as large as 2^n - 1. */
3963 abs_inc = INTVAL (increment);
3965 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
3966 else if (abs_inc < 0)
3968 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
3974 /* For NE tests, make sure that the iteration variable won't miss
3975 the final value. If abs_diff mod abs_incr is not zero, then the
3976 iteration variable will overflow before the loop exits, and we
3977 can not calculate the number of iterations. */
3978 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
3981 /* Note that the number of iterations could be calculated using
3982 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3983 handle potential overflow of the summation. */
3984 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
3985 return loop_info->n_iterations;
3989 /* Replace uses of split bivs with their split pseudo register. This is
3990 for original instructions which remain after loop unrolling without
3994 remap_split_bivs (x)
3997 register enum rtx_code code;
3999 register const char *fmt;
4004 code = GET_CODE (x);
4019 /* If non-reduced/final-value givs were split, then this would also
4020 have to remap those givs also. */
4022 if (REGNO (x) < max_reg_before_loop
4023 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
4024 return reg_biv_class[REGNO (x)]->biv->src_reg;
4031 fmt = GET_RTX_FORMAT (code);
4032 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4035 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
4039 for (j = 0; j < XVECLEN (x, i); j++)
4040 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
4046 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4047 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4048 return 0. COPY_START is where we can start looking for the insns
4049 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4052 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4053 must dominate LAST_UID.
4055 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4056 may not dominate LAST_UID.
4058 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4059 must dominate LAST_UID. */
4062 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4069 int passed_jump = 0;
4070 rtx p = NEXT_INSN (copy_start);
4072 while (INSN_UID (p) != first_uid)
4074 if (GET_CODE (p) == JUMP_INSN)
4076 /* Could not find FIRST_UID. */
4082 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4083 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
4084 || ! dead_or_set_regno_p (p, regno))
4087 /* FIRST_UID is always executed. */
4088 if (passed_jump == 0)
4091 while (INSN_UID (p) != last_uid)
4093 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4094 can not be sure that FIRST_UID dominates LAST_UID. */
4095 if (GET_CODE (p) == CODE_LABEL)
4097 /* Could not find LAST_UID, but we reached the end of the loop, so
4099 else if (p == copy_end)
4104 /* FIRST_UID is always executed if LAST_UID is executed. */