1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001
3 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor { int factor, count; }
144 factors[NUM_FACTORS] = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
159 #include "insn-config.h"
160 #include "integrate.h"
164 #include "function.h"
169 #include "hard-reg-set.h"
170 #include "basic-block.h"
173 /* This controls which loops are unrolled, and by how much we unroll
176 #ifndef MAX_UNROLLED_INSNS
177 #define MAX_UNROLLED_INSNS 100
180 /* Indexed by register number, if non-zero, then it contains a pointer
181 to a struct induction for a DEST_REG giv which has been combined with
182 one of more address givs. This is needed because whenever such a DEST_REG
183 giv is modified, we must modify the value of all split address givs
184 that were combined with this DEST_REG giv. */
186 static struct induction **addr_combined_regs;
188 /* Indexed by register number, if this is a splittable induction variable,
189 then this will hold the current value of the register, which depends on the
192 static rtx *splittable_regs;
194 /* Indexed by register number, if this is a splittable induction variable,
195 then this will hold the number of instructions in the loop that modify
196 the induction variable. Used to ensure that only the last insn modifying
197 a split iv will update the original iv of the dest. */
199 static int *splittable_regs_updates;
201 /* Forward declarations. */
203 static void init_reg_map PARAMS ((struct inline_remap *, int));
204 static rtx calculate_giv_inc PARAMS ((rtx, rtx, unsigned int));
205 static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
206 static void final_reg_note_copy PARAMS ((rtx *, struct inline_remap *));
207 static void copy_loop_body PARAMS ((struct loop *, rtx, rtx,
208 struct inline_remap *, rtx, int,
209 enum unroll_types, rtx, rtx, rtx, rtx));
210 static int find_splittable_regs PARAMS ((const struct loop *,
211 enum unroll_types, int));
212 static int find_splittable_givs PARAMS ((const struct loop *,
213 struct iv_class *, enum unroll_types,
215 static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
216 static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
217 static int verify_addresses PARAMS ((struct induction *, rtx, int));
218 static rtx remap_split_bivs PARAMS ((struct loop *, rtx));
219 static rtx find_common_reg_term PARAMS ((rtx, rtx));
220 static rtx subtract_reg_term PARAMS ((rtx, rtx));
221 static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
222 static rtx ujump_to_loop_cont PARAMS ((rtx, rtx));
224 /* Try to unroll one loop and split induction variables in the loop.
226 The loop is described by the arguments LOOP and INSN_COUNT.
227 STRENGTH_REDUCTION_P indicates whether information generated in the
228 strength reduction pass is available.
230 This function is intended to be called from within `strength_reduce'
234 unroll_loop (loop, insn_count, strength_reduce_p)
237 int strength_reduce_p;
239 struct loop_info *loop_info = LOOP_INFO (loop);
240 struct loop_ivs *ivs = LOOP_IVS (loop);
243 unsigned HOST_WIDE_INT temp;
244 int unroll_number = 1;
245 rtx copy_start, copy_end;
246 rtx insn, sequence, pattern, tem;
247 int max_labelno, max_insnno;
249 struct inline_remap *map;
250 char *local_label = NULL;
252 unsigned int max_local_regnum;
253 unsigned int maxregnum;
257 int splitting_not_safe = 0;
258 enum unroll_types unroll_type = UNROLL_NAIVE;
259 int loop_preconditioned = 0;
261 /* This points to the last real insn in the loop, which should be either
262 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
265 rtx loop_start = loop->start;
266 rtx loop_end = loop->end;
268 /* Don't bother unrolling huge loops. Since the minimum factor is
269 two, loops greater than one half of MAX_UNROLLED_INSNS will never
271 if (insn_count > MAX_UNROLLED_INSNS / 2)
273 if (loop_dump_stream)
274 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
278 /* When emitting debugger info, we can't unroll loops with unequal numbers
279 of block_beg and block_end notes, because that would unbalance the block
280 structure of the function. This can happen as a result of the
281 "if (foo) bar; else break;" optimization in jump.c. */
282 /* ??? Gcc has a general policy that -g is never supposed to change the code
283 that the compiler emits, so we must disable this optimization always,
284 even if debug info is not being output. This is rare, so this should
285 not be a significant performance problem. */
287 if (1 /* write_symbols != NO_DEBUG */)
289 int block_begins = 0;
292 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
294 if (GET_CODE (insn) == NOTE)
296 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
298 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
300 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
301 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
303 /* Note, would be nice to add code to unroll EH
304 regions, but until that time, we punt (don't
305 unroll). For the proper way of doing it, see
306 expand_inline_function. */
308 if (loop_dump_stream)
309 fprintf (loop_dump_stream,
310 "Unrolling failure: cannot unroll EH regions.\n");
316 if (block_begins != block_ends)
318 if (loop_dump_stream)
319 fprintf (loop_dump_stream,
320 "Unrolling failure: Unbalanced block notes.\n");
325 /* Determine type of unroll to perform. Depends on the number of iterations
326 and the size of the loop. */
328 /* If there is no strength reduce info, then set
329 loop_info->n_iterations to zero. This can happen if
330 strength_reduce can't find any bivs in the loop. A value of zero
331 indicates that the number of iterations could not be calculated. */
333 if (! strength_reduce_p)
334 loop_info->n_iterations = 0;
336 if (loop_dump_stream && loop_info->n_iterations > 0)
338 fputs ("Loop unrolling: ", loop_dump_stream);
339 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
340 loop_info->n_iterations);
341 fputs (" iterations.\n", loop_dump_stream);
344 /* Find and save a pointer to the last nonnote insn in the loop. */
346 last_loop_insn = prev_nonnote_insn (loop_end);
348 /* Calculate how many times to unroll the loop. Indicate whether or
349 not the loop is being completely unrolled. */
351 if (loop_info->n_iterations == 1)
353 /* Handle the case where the loop begins with an unconditional
354 jump to the loop condition. Make sure to delete the jump
355 insn, otherwise the loop body will never execute. */
357 rtx ujump = ujump_to_loop_cont (loop->start, loop->cont);
361 /* If number of iterations is exactly 1, then eliminate the compare and
362 branch at the end of the loop since they will never be taken.
363 Then return, since no other action is needed here. */
365 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
366 don't do anything. */
368 if (GET_CODE (last_loop_insn) == BARRIER)
370 /* Delete the jump insn. This will delete the barrier also. */
371 delete_insn (PREV_INSN (last_loop_insn));
373 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
376 rtx prev = PREV_INSN (last_loop_insn);
378 delete_insn (last_loop_insn);
380 /* The immediately preceding insn may be a compare which must be
382 if (only_sets_cc0_p (prev))
387 /* Remove the loop notes since this is no longer a loop. */
389 delete_insn (loop->vtop);
391 delete_insn (loop->cont);
393 delete_insn (loop_start);
395 delete_insn (loop_end);
399 else if (loop_info->n_iterations > 0
400 /* Avoid overflow in the next expression. */
401 && loop_info->n_iterations < MAX_UNROLLED_INSNS
402 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
404 unroll_number = loop_info->n_iterations;
405 unroll_type = UNROLL_COMPLETELY;
407 else if (loop_info->n_iterations > 0)
409 /* Try to factor the number of iterations. Don't bother with the
410 general case, only using 2, 3, 5, and 7 will get 75% of all
411 numbers theoretically, and almost all in practice. */
413 for (i = 0; i < NUM_FACTORS; i++)
414 factors[i].count = 0;
416 temp = loop_info->n_iterations;
417 for (i = NUM_FACTORS - 1; i >= 0; i--)
418 while (temp % factors[i].factor == 0)
421 temp = temp / factors[i].factor;
424 /* Start with the larger factors first so that we generally
425 get lots of unrolling. */
429 for (i = 3; i >= 0; i--)
430 while (factors[i].count--)
432 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
434 unroll_number *= factors[i].factor;
435 temp *= factors[i].factor;
441 /* If we couldn't find any factors, then unroll as in the normal
443 if (unroll_number == 1)
445 if (loop_dump_stream)
446 fprintf (loop_dump_stream, "Loop unrolling: No factors found.\n");
449 unroll_type = UNROLL_MODULO;
452 /* Default case, calculate number of times to unroll loop based on its
454 if (unroll_type == UNROLL_NAIVE)
456 if (8 * insn_count < MAX_UNROLLED_INSNS)
458 else if (4 * insn_count < MAX_UNROLLED_INSNS)
464 /* Now we know how many times to unroll the loop. */
466 if (loop_dump_stream)
467 fprintf (loop_dump_stream, "Unrolling loop %d times.\n", unroll_number);
469 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
471 /* Loops of these types can start with jump down to the exit condition
472 in rare circumstances.
474 Consider a pair of nested loops where the inner loop is part
475 of the exit code for the outer loop.
477 In this case jump.c will not duplicate the exit test for the outer
478 loop, so it will start with a jump to the exit code.
480 Then consider if the inner loop turns out to iterate once and
481 only once. We will end up deleting the jumps associated with
482 the inner loop. However, the loop notes are not removed from
483 the instruction stream.
485 And finally assume that we can compute the number of iterations
488 In this case unroll may want to unroll the outer loop even though
489 it starts with a jump to the outer loop's exit code.
491 We could try to optimize this case, but it hardly seems worth it.
492 Just return without unrolling the loop in such cases. */
495 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
496 insn = NEXT_INSN (insn);
497 if (GET_CODE (insn) == JUMP_INSN)
501 if (unroll_type == UNROLL_COMPLETELY)
503 /* Completely unrolling the loop: Delete the compare and branch at
504 the end (the last two instructions). This delete must done at the
505 very end of loop unrolling, to avoid problems with calls to
506 back_branch_in_range_p, which is called by find_splittable_regs.
507 All increments of splittable bivs/givs are changed to load constant
510 copy_start = loop_start;
512 /* Set insert_before to the instruction immediately after the JUMP_INSN
513 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
514 the loop will be correctly handled by copy_loop_body. */
515 insert_before = NEXT_INSN (last_loop_insn);
517 /* Set copy_end to the insn before the jump at the end of the loop. */
518 if (GET_CODE (last_loop_insn) == BARRIER)
519 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
520 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
522 copy_end = PREV_INSN (last_loop_insn);
524 /* The instruction immediately before the JUMP_INSN may be a compare
525 instruction which we do not want to copy. */
526 if (sets_cc0_p (PREV_INSN (copy_end)))
527 copy_end = PREV_INSN (copy_end);
532 /* We currently can't unroll a loop if it doesn't end with a
533 JUMP_INSN. There would need to be a mechanism that recognizes
534 this case, and then inserts a jump after each loop body, which
535 jumps to after the last loop body. */
536 if (loop_dump_stream)
537 fprintf (loop_dump_stream,
538 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
542 else if (unroll_type == UNROLL_MODULO)
544 /* Partially unrolling the loop: The compare and branch at the end
545 (the last two instructions) must remain. Don't copy the compare
546 and branch instructions at the end of the loop. Insert the unrolled
547 code immediately before the compare/branch at the end so that the
548 code will fall through to them as before. */
550 copy_start = loop_start;
552 /* Set insert_before to the jump insn at the end of the loop.
553 Set copy_end to before the jump insn at the end of the loop. */
554 if (GET_CODE (last_loop_insn) == BARRIER)
556 insert_before = PREV_INSN (last_loop_insn);
557 copy_end = PREV_INSN (insert_before);
559 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
561 insert_before = last_loop_insn;
563 /* The instruction immediately before the JUMP_INSN may be a compare
564 instruction which we do not want to copy or delete. */
565 if (sets_cc0_p (PREV_INSN (insert_before)))
566 insert_before = PREV_INSN (insert_before);
568 copy_end = PREV_INSN (insert_before);
572 /* We currently can't unroll a loop if it doesn't end with a
573 JUMP_INSN. There would need to be a mechanism that recognizes
574 this case, and then inserts a jump after each loop body, which
575 jumps to after the last loop body. */
576 if (loop_dump_stream)
577 fprintf (loop_dump_stream,
578 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
584 /* Normal case: Must copy the compare and branch instructions at the
587 if (GET_CODE (last_loop_insn) == BARRIER)
589 /* Loop ends with an unconditional jump and a barrier.
590 Handle this like above, don't copy jump and barrier.
591 This is not strictly necessary, but doing so prevents generating
592 unconditional jumps to an immediately following label.
594 This will be corrected below if the target of this jump is
595 not the start_label. */
597 insert_before = PREV_INSN (last_loop_insn);
598 copy_end = PREV_INSN (insert_before);
600 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
602 /* Set insert_before to immediately after the JUMP_INSN, so that
603 NOTEs at the end of the loop will be correctly handled by
605 insert_before = NEXT_INSN (last_loop_insn);
606 copy_end = last_loop_insn;
610 /* We currently can't unroll a loop if it doesn't end with a
611 JUMP_INSN. There would need to be a mechanism that recognizes
612 this case, and then inserts a jump after each loop body, which
613 jumps to after the last loop body. */
614 if (loop_dump_stream)
615 fprintf (loop_dump_stream,
616 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
620 /* If copying exit test branches because they can not be eliminated,
621 then must convert the fall through case of the branch to a jump past
622 the end of the loop. Create a label to emit after the loop and save
623 it for later use. Do not use the label after the loop, if any, since
624 it might be used by insns outside the loop, or there might be insns
625 added before it later by final_[bg]iv_value which must be after
626 the real exit label. */
627 exit_label = gen_label_rtx ();
630 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
631 insn = NEXT_INSN (insn);
633 if (GET_CODE (insn) == JUMP_INSN)
635 /* The loop starts with a jump down to the exit condition test.
636 Start copying the loop after the barrier following this
638 copy_start = NEXT_INSN (insn);
640 /* Splitting induction variables doesn't work when the loop is
641 entered via a jump to the bottom, because then we end up doing
642 a comparison against a new register for a split variable, but
643 we did not execute the set insn for the new register because
644 it was skipped over. */
645 splitting_not_safe = 1;
646 if (loop_dump_stream)
647 fprintf (loop_dump_stream,
648 "Splitting not safe, because loop not entered at top.\n");
651 copy_start = loop_start;
654 /* This should always be the first label in the loop. */
655 start_label = NEXT_INSN (copy_start);
656 /* There may be a line number note and/or a loop continue note here. */
657 while (GET_CODE (start_label) == NOTE)
658 start_label = NEXT_INSN (start_label);
659 if (GET_CODE (start_label) != CODE_LABEL)
661 /* This can happen as a result of jump threading. If the first insns in
662 the loop test the same condition as the loop's backward jump, or the
663 opposite condition, then the backward jump will be modified to point
664 to elsewhere, and the loop's start label is deleted.
666 This case currently can not be handled by the loop unrolling code. */
668 if (loop_dump_stream)
669 fprintf (loop_dump_stream,
670 "Unrolling failure: unknown insns between BEG note and loop label.\n");
673 if (LABEL_NAME (start_label))
675 /* The jump optimization pass must have combined the original start label
676 with a named label for a goto. We can't unroll this case because
677 jumps which go to the named label must be handled differently than
678 jumps to the loop start, and it is impossible to differentiate them
680 if (loop_dump_stream)
681 fprintf (loop_dump_stream,
682 "Unrolling failure: loop start label is gone\n");
686 if (unroll_type == UNROLL_NAIVE
687 && GET_CODE (last_loop_insn) == BARRIER
688 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
689 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
691 /* In this case, we must copy the jump and barrier, because they will
692 not be converted to jumps to an immediately following label. */
694 insert_before = NEXT_INSN (last_loop_insn);
695 copy_end = last_loop_insn;
698 if (unroll_type == UNROLL_NAIVE
699 && GET_CODE (last_loop_insn) == JUMP_INSN
700 && start_label != JUMP_LABEL (last_loop_insn))
702 /* ??? The loop ends with a conditional branch that does not branch back
703 to the loop start label. In this case, we must emit an unconditional
704 branch to the loop exit after emitting the final branch.
705 copy_loop_body does not have support for this currently, so we
706 give up. It doesn't seem worthwhile to unroll anyways since
707 unrolling would increase the number of branch instructions
709 if (loop_dump_stream)
710 fprintf (loop_dump_stream,
711 "Unrolling failure: final conditional branch not to loop start\n");
715 /* Allocate a translation table for the labels and insn numbers.
716 They will be filled in as we copy the insns in the loop. */
718 max_labelno = max_label_num ();
719 max_insnno = get_max_uid ();
721 /* Various paths through the unroll code may reach the "egress" label
722 without initializing fields within the map structure.
724 To be safe, we use xcalloc to zero the memory. */
725 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
727 /* Allocate the label map. */
731 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
733 local_label = (char *) xcalloc (max_labelno, sizeof (char));
736 /* Search the loop and mark all local labels, i.e. the ones which have to
737 be distinct labels when copied. For all labels which might be
738 non-local, set their label_map entries to point to themselves.
739 If they happen to be local their label_map entries will be overwritten
740 before the loop body is copied. The label_map entries for local labels
741 will be set to a different value each time the loop body is copied. */
743 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
747 if (GET_CODE (insn) == CODE_LABEL)
748 local_label[CODE_LABEL_NUMBER (insn)] = 1;
749 else if (GET_CODE (insn) == JUMP_INSN)
751 if (JUMP_LABEL (insn))
752 set_label_in_map (map,
753 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
755 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
756 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
758 rtx pat = PATTERN (insn);
759 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
760 int len = XVECLEN (pat, diff_vec_p);
763 for (i = 0; i < len; i++)
765 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
766 set_label_in_map (map, CODE_LABEL_NUMBER (label), label);
770 if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
771 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
775 /* Allocate space for the insn map. */
777 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
779 /* Set this to zero, to indicate that we are doing loop unrolling,
780 not function inlining. */
781 map->inline_target = 0;
783 /* The register and constant maps depend on the number of registers
784 present, so the final maps can't be created until after
785 find_splittable_regs is called. However, they are needed for
786 preconditioning, so we create temporary maps when preconditioning
789 /* The preconditioning code may allocate two new pseudo registers. */
790 maxregnum = max_reg_num ();
792 /* local_regno is only valid for regnos < max_local_regnum. */
793 max_local_regnum = maxregnum;
795 /* Allocate and zero out the splittable_regs and addr_combined_regs
796 arrays. These must be zeroed here because they will be used if
797 loop preconditioning is performed, and must be zero for that case.
799 It is safe to do this here, since the extra registers created by the
800 preconditioning code and find_splittable_regs will never be used
801 to access the splittable_regs[] and addr_combined_regs[] arrays. */
803 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
804 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
806 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
807 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
809 /* Mark all local registers, i.e. the ones which are referenced only
811 if (INSN_UID (copy_end) < max_uid_for_loop)
813 int copy_start_luid = INSN_LUID (copy_start);
814 int copy_end_luid = INSN_LUID (copy_end);
816 /* If a register is used in the jump insn, we must not duplicate it
817 since it will also be used outside the loop. */
818 if (GET_CODE (copy_end) == JUMP_INSN)
821 /* If we have a target that uses cc0, then we also must not duplicate
822 the insn that sets cc0 before the jump insn, if one is present. */
824 if (GET_CODE (copy_end) == JUMP_INSN
825 && sets_cc0_p (PREV_INSN (copy_end)))
829 /* If copy_start points to the NOTE that starts the loop, then we must
830 use the next luid, because invariant pseudo-regs moved out of the loop
831 have their lifetimes modified to start here, but they are not safe
833 if (copy_start == loop_start)
836 /* If a pseudo's lifetime is entirely contained within this loop, then we
837 can use a different pseudo in each unrolled copy of the loop. This
838 results in better code. */
839 /* We must limit the generic test to max_reg_before_loop, because only
840 these pseudo registers have valid regno_first_uid info. */
841 for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r)
842 if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) <= max_uid_for_loop
843 && REGNO_FIRST_LUID (r) >= copy_start_luid
844 && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) <= max_uid_for_loop
845 && REGNO_LAST_LUID (r) <= copy_end_luid)
847 /* However, we must also check for loop-carried dependencies.
848 If the value the pseudo has at the end of iteration X is
849 used by iteration X+1, then we can not use a different pseudo
850 for each unrolled copy of the loop. */
851 /* A pseudo is safe if regno_first_uid is a set, and this
852 set dominates all instructions from regno_first_uid to
854 /* ??? This check is simplistic. We would get better code if
855 this check was more sophisticated. */
856 if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r),
857 copy_start, copy_end))
860 if (loop_dump_stream)
863 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
865 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
871 /* If this loop requires exit tests when unrolled, check to see if we
872 can precondition the loop so as to make the exit tests unnecessary.
873 Just like variable splitting, this is not safe if the loop is entered
874 via a jump to the bottom. Also, can not do this if no strength
875 reduce info, because precondition_loop_p uses this info. */
877 /* Must copy the loop body for preconditioning before the following
878 find_splittable_regs call since that will emit insns which need to
879 be after the preconditioned loop copies, but immediately before the
880 unrolled loop copies. */
882 /* Also, it is not safe to split induction variables for the preconditioned
883 copies of the loop body. If we split induction variables, then the code
884 assumes that each induction variable can be represented as a function
885 of its initial value and the loop iteration number. This is not true
886 in this case, because the last preconditioned copy of the loop body
887 could be any iteration from the first up to the `unroll_number-1'th,
888 depending on the initial value of the iteration variable. Therefore
889 we can not split induction variables here, because we can not calculate
890 their value. Hence, this code must occur before find_splittable_regs
893 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
895 rtx initial_value, final_value, increment;
896 enum machine_mode mode;
898 if (precondition_loop_p (loop,
899 &initial_value, &final_value, &increment,
904 int abs_inc, neg_inc;
906 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
908 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
909 "unroll_loop_precondition");
910 global_const_equiv_varray = map->const_equiv_varray;
912 init_reg_map (map, maxregnum);
914 /* Limit loop unrolling to 4, since this will make 7 copies of
916 if (unroll_number > 4)
919 /* Save the absolute value of the increment, and also whether or
920 not it is negative. */
922 abs_inc = INTVAL (increment);
931 /* Calculate the difference between the final and initial values.
932 Final value may be a (plus (reg x) (const_int 1)) rtx.
933 Let the following cse pass simplify this if initial value is
936 We must copy the final and initial values here to avoid
937 improperly shared rtl. */
939 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
940 copy_rtx (initial_value), NULL_RTX, 0,
943 /* Now calculate (diff % (unroll * abs (increment))) by using an
945 diff = expand_binop (GET_MODE (diff), and_optab, diff,
946 GEN_INT (unroll_number * abs_inc - 1),
947 NULL_RTX, 0, OPTAB_LIB_WIDEN);
949 /* Now emit a sequence of branches to jump to the proper precond
952 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
953 for (i = 0; i < unroll_number; i++)
954 labels[i] = gen_label_rtx ();
956 /* Check for the case where the initial value is greater than or
957 equal to the final value. In that case, we want to execute
958 exactly one loop iteration. The code below will fail for this
959 case. This check does not apply if the loop has a NE
960 comparison at the end. */
962 if (loop_info->comparison_code != NE)
964 emit_cmp_and_jump_insns (initial_value, final_value,
966 NULL_RTX, mode, 0, 0, labels[1]);
967 predict_insn_def (get_last_insn (), PRED_LOOP_CONDITION, NOT_TAKEN);
968 JUMP_LABEL (get_last_insn ()) = labels[1];
969 LABEL_NUSES (labels[1])++;
972 /* Assuming the unroll_number is 4, and the increment is 2, then
973 for a negative increment: for a positive increment:
974 diff = 0,1 precond 0 diff = 0,7 precond 0
975 diff = 2,3 precond 3 diff = 1,2 precond 1
976 diff = 4,5 precond 2 diff = 3,4 precond 2
977 diff = 6,7 precond 1 diff = 5,6 precond 3 */
979 /* We only need to emit (unroll_number - 1) branches here, the
980 last case just falls through to the following code. */
982 /* ??? This would give better code if we emitted a tree of branches
983 instead of the current linear list of branches. */
985 for (i = 0; i < unroll_number - 1; i++)
988 enum rtx_code cmp_code;
990 /* For negative increments, must invert the constant compared
991 against, except when comparing against zero. */
999 cmp_const = unroll_number - i;
1008 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
1009 cmp_code, NULL_RTX, mode, 0, 0,
1011 JUMP_LABEL (get_last_insn ()) = labels[i];
1012 LABEL_NUSES (labels[i])++;
1013 predict_insn (get_last_insn (), PRED_LOOP_PRECONDITIONING,
1014 REG_BR_PROB_BASE / (unroll_number - i));
1017 /* If the increment is greater than one, then we need another branch,
1018 to handle other cases equivalent to 0. */
1020 /* ??? This should be merged into the code above somehow to help
1021 simplify the code here, and reduce the number of branches emitted.
1022 For the negative increment case, the branch here could easily
1023 be merged with the `0' case branch above. For the positive
1024 increment case, it is not clear how this can be simplified. */
1029 enum rtx_code cmp_code;
1033 cmp_const = abs_inc - 1;
1038 cmp_const = abs_inc * (unroll_number - 1) + 1;
1042 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1043 NULL_RTX, mode, 0, 0, labels[0]);
1044 JUMP_LABEL (get_last_insn ()) = labels[0];
1045 LABEL_NUSES (labels[0])++;
1048 sequence = gen_sequence ();
1050 loop_insn_hoist (loop, sequence);
1052 /* Only the last copy of the loop body here needs the exit
1053 test, so set copy_end to exclude the compare/branch here,
1054 and then reset it inside the loop when get to the last
1057 if (GET_CODE (last_loop_insn) == BARRIER)
1058 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1059 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1061 copy_end = PREV_INSN (last_loop_insn);
1063 /* The immediately preceding insn may be a compare which
1064 we do not want to copy. */
1065 if (sets_cc0_p (PREV_INSN (copy_end)))
1066 copy_end = PREV_INSN (copy_end);
1072 for (i = 1; i < unroll_number; i++)
1074 emit_label_after (labels[unroll_number - i],
1075 PREV_INSN (loop_start));
1077 memset ((char *) map->insn_map, 0, max_insnno * sizeof (rtx));
1078 memset ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1079 0, (VARRAY_SIZE (map->const_equiv_varray)
1080 * sizeof (struct const_equiv_data)));
1083 for (j = 0; j < max_labelno; j++)
1085 set_label_in_map (map, j, gen_label_rtx ());
1087 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1091 = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1092 record_base_value (REGNO (map->reg_map[r]),
1093 regno_reg_rtx[r], 0);
1095 /* The last copy needs the compare/branch insns at the end,
1096 so reset copy_end here if the loop ends with a conditional
1099 if (i == unroll_number - 1)
1101 if (GET_CODE (last_loop_insn) == BARRIER)
1102 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1104 copy_end = last_loop_insn;
1107 /* None of the copies are the `last_iteration', so just
1108 pass zero for that parameter. */
1109 copy_loop_body (loop, copy_start, copy_end, map, exit_label, 0,
1110 unroll_type, start_label, loop_end,
1111 loop_start, copy_end);
1113 emit_label_after (labels[0], PREV_INSN (loop_start));
1115 if (GET_CODE (last_loop_insn) == BARRIER)
1117 insert_before = PREV_INSN (last_loop_insn);
1118 copy_end = PREV_INSN (insert_before);
1122 insert_before = last_loop_insn;
1124 /* The instruction immediately before the JUMP_INSN may
1125 be a compare instruction which we do not want to copy
1127 if (sets_cc0_p (PREV_INSN (insert_before)))
1128 insert_before = PREV_INSN (insert_before);
1130 copy_end = PREV_INSN (insert_before);
1133 /* Set unroll type to MODULO now. */
1134 unroll_type = UNROLL_MODULO;
1135 loop_preconditioned = 1;
1142 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1143 the loop unless all loops are being unrolled. */
1144 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1146 if (loop_dump_stream)
1147 fprintf (loop_dump_stream,
1148 "Unrolling failure: Naive unrolling not being done.\n");
1152 /* At this point, we are guaranteed to unroll the loop. */
1154 /* Keep track of the unroll factor for the loop. */
1155 loop_info->unroll_number = unroll_number;
1157 /* For each biv and giv, determine whether it can be safely split into
1158 a different variable for each unrolled copy of the loop body.
1159 We precalculate and save this info here, since computing it is
1162 Do this before deleting any instructions from the loop, so that
1163 back_branch_in_range_p will work correctly. */
1165 if (splitting_not_safe)
1168 temp = find_splittable_regs (loop, unroll_type, unroll_number);
1170 /* find_splittable_regs may have created some new registers, so must
1171 reallocate the reg_map with the new larger size, and must realloc
1172 the constant maps also. */
1174 maxregnum = max_reg_num ();
1175 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1177 init_reg_map (map, maxregnum);
1179 if (map->const_equiv_varray == 0)
1180 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1181 maxregnum + temp * unroll_number * 2,
1183 global_const_equiv_varray = map->const_equiv_varray;
1185 /* Search the list of bivs and givs to find ones which need to be remapped
1186 when split, and set their reg_map entry appropriately. */
1188 for (bl = ivs->list; bl; bl = bl->next)
1190 if (REGNO (bl->biv->src_reg) != bl->regno)
1191 map->reg_map[bl->regno] = bl->biv->src_reg;
1193 /* Currently, non-reduced/final-value givs are never split. */
1194 for (v = bl->giv; v; v = v->next_iv)
1195 if (REGNO (v->src_reg) != bl->regno)
1196 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1200 /* Use our current register alignment and pointer flags. */
1201 map->regno_pointer_align = cfun->emit->regno_pointer_align;
1202 map->x_regno_reg_rtx = cfun->emit->x_regno_reg_rtx;
1204 /* If the loop is being partially unrolled, and the iteration variables
1205 are being split, and are being renamed for the split, then must fix up
1206 the compare/jump instruction at the end of the loop to refer to the new
1207 registers. This compare isn't copied, so the registers used in it
1208 will never be replaced if it isn't done here. */
1210 if (unroll_type == UNROLL_MODULO)
1212 insn = NEXT_INSN (copy_end);
1213 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1214 PATTERN (insn) = remap_split_bivs (loop, PATTERN (insn));
1217 /* For unroll_number times, make a copy of each instruction
1218 between copy_start and copy_end, and insert these new instructions
1219 before the end of the loop. */
1221 for (i = 0; i < unroll_number; i++)
1223 memset ((char *) map->insn_map, 0, max_insnno * sizeof (rtx));
1224 memset ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0), 0,
1225 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1228 for (j = 0; j < max_labelno; j++)
1230 set_label_in_map (map, j, gen_label_rtx ());
1232 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1235 map->reg_map[r] = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1236 record_base_value (REGNO (map->reg_map[r]),
1237 regno_reg_rtx[r], 0);
1240 /* If loop starts with a branch to the test, then fix it so that
1241 it points to the test of the first unrolled copy of the loop. */
1242 if (i == 0 && loop_start != copy_start)
1244 insn = PREV_INSN (copy_start);
1245 pattern = PATTERN (insn);
1247 tem = get_label_from_map (map,
1249 (XEXP (SET_SRC (pattern), 0)));
1250 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1252 /* Set the jump label so that it can be used by later loop unrolling
1254 JUMP_LABEL (insn) = tem;
1255 LABEL_NUSES (tem)++;
1258 copy_loop_body (loop, copy_start, copy_end, map, exit_label,
1259 i == unroll_number - 1, unroll_type, start_label,
1260 loop_end, insert_before, insert_before);
1263 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1264 insn to be deleted. This prevents any runaway delete_insn call from
1265 more insns that it should, as it always stops at a CODE_LABEL. */
1267 /* Delete the compare and branch at the end of the loop if completely
1268 unrolling the loop. Deleting the backward branch at the end also
1269 deletes the code label at the start of the loop. This is done at
1270 the very end to avoid problems with back_branch_in_range_p. */
1272 if (unroll_type == UNROLL_COMPLETELY)
1273 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1275 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1277 /* Delete all of the original loop instructions. Don't delete the
1278 LOOP_BEG note, or the first code label in the loop. */
1280 insn = NEXT_INSN (copy_start);
1281 while (insn != safety_label)
1283 /* ??? Don't delete named code labels. They will be deleted when the
1284 jump that references them is deleted. Otherwise, we end up deleting
1285 them twice, which causes them to completely disappear instead of turn
1286 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1287 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1288 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1289 associated LABEL_DECL to point to one of the new label instances. */
1290 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1291 if (insn != start_label
1292 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1293 && ! (GET_CODE (insn) == NOTE
1294 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1295 insn = delete_insn (insn);
1297 insn = NEXT_INSN (insn);
1300 /* Can now delete the 'safety' label emitted to protect us from runaway
1301 delete_insn calls. */
1302 if (INSN_DELETED_P (safety_label))
1304 delete_insn (safety_label);
1306 /* If exit_label exists, emit it after the loop. Doing the emit here
1307 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1308 This is needed so that mostly_true_jump in reorg.c will treat jumps
1309 to this loop end label correctly, i.e. predict that they are usually
1312 emit_label_after (exit_label, loop_end);
1315 if (unroll_type == UNROLL_COMPLETELY)
1317 /* Remove the loop notes since this is no longer a loop. */
1319 delete_insn (loop->vtop);
1321 delete_insn (loop->cont);
1323 delete_insn (loop_start);
1325 delete_insn (loop_end);
1328 if (map->const_equiv_varray)
1329 VARRAY_FREE (map->const_equiv_varray);
1332 free (map->label_map);
1335 free (map->insn_map);
1336 free (splittable_regs);
1337 free (splittable_regs_updates);
1338 free (addr_combined_regs);
1341 free (map->reg_map);
1345 /* Return true if the loop can be safely, and profitably, preconditioned
1346 so that the unrolled copies of the loop body don't need exit tests.
1348 This only works if final_value, initial_value and increment can be
1349 determined, and if increment is a constant power of 2.
1350 If increment is not a power of 2, then the preconditioning modulo
1351 operation would require a real modulo instead of a boolean AND, and this
1352 is not considered `profitable'. */
1354 /* ??? If the loop is known to be executed very many times, or the machine
1355 has a very cheap divide instruction, then preconditioning is a win even
1356 when the increment is not a power of 2. Use RTX_COST to compute
1357 whether divide is cheap.
1358 ??? A divide by constant doesn't actually need a divide, look at
1359 expand_divmod. The reduced cost of this optimized modulo is not
1360 reflected in RTX_COST. */
1363 precondition_loop_p (loop, initial_value, final_value, increment, mode)
1364 const struct loop *loop;
1365 rtx *initial_value, *final_value, *increment;
1366 enum machine_mode *mode;
1368 rtx loop_start = loop->start;
1369 struct loop_info *loop_info = LOOP_INFO (loop);
1371 if (loop_info->n_iterations > 0)
1373 *initial_value = const0_rtx;
1374 *increment = const1_rtx;
1375 *final_value = GEN_INT (loop_info->n_iterations);
1378 if (loop_dump_stream)
1380 fputs ("Preconditioning: Success, number of iterations known, ",
1382 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1383 loop_info->n_iterations);
1384 fputs (".\n", loop_dump_stream);
1389 if (loop_info->iteration_var == 0)
1391 if (loop_dump_stream)
1392 fprintf (loop_dump_stream,
1393 "Preconditioning: Could not find iteration variable.\n");
1396 else if (loop_info->initial_value == 0)
1398 if (loop_dump_stream)
1399 fprintf (loop_dump_stream,
1400 "Preconditioning: Could not find initial value.\n");
1403 else if (loop_info->increment == 0)
1405 if (loop_dump_stream)
1406 fprintf (loop_dump_stream,
1407 "Preconditioning: Could not find increment value.\n");
1410 else if (GET_CODE (loop_info->increment) != CONST_INT)
1412 if (loop_dump_stream)
1413 fprintf (loop_dump_stream,
1414 "Preconditioning: Increment not a constant.\n");
1417 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1418 && (exact_log2 (-INTVAL (loop_info->increment)) < 0))
1420 if (loop_dump_stream)
1421 fprintf (loop_dump_stream,
1422 "Preconditioning: Increment not a constant power of 2.\n");
1426 /* Unsigned_compare and compare_dir can be ignored here, since they do
1427 not matter for preconditioning. */
1429 if (loop_info->final_value == 0)
1431 if (loop_dump_stream)
1432 fprintf (loop_dump_stream,
1433 "Preconditioning: EQ comparison loop.\n");
1437 /* Must ensure that final_value is invariant, so call
1438 loop_invariant_p to check. Before doing so, must check regno
1439 against max_reg_before_loop to make sure that the register is in
1440 the range covered by loop_invariant_p. If it isn't, then it is
1441 most likely a biv/giv which by definition are not invariant. */
1442 if ((GET_CODE (loop_info->final_value) == REG
1443 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1444 || (GET_CODE (loop_info->final_value) == PLUS
1445 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1446 || ! loop_invariant_p (loop, loop_info->final_value))
1448 if (loop_dump_stream)
1449 fprintf (loop_dump_stream,
1450 "Preconditioning: Final value not invariant.\n");
1454 /* Fail for floating point values, since the caller of this function
1455 does not have code to deal with them. */
1456 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1457 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1459 if (loop_dump_stream)
1460 fprintf (loop_dump_stream,
1461 "Preconditioning: Floating point final or initial value.\n");
1465 /* Fail if loop_info->iteration_var is not live before loop_start,
1466 since we need to test its value in the preconditioning code. */
1468 if (REGNO_FIRST_LUID (REGNO (loop_info->iteration_var))
1469 > INSN_LUID (loop_start))
1471 if (loop_dump_stream)
1472 fprintf (loop_dump_stream,
1473 "Preconditioning: Iteration var not live before loop start.\n");
1477 /* Note that loop_iterations biases the initial value for GIV iterators
1478 such as "while (i-- > 0)" so that we can calculate the number of
1479 iterations just like for BIV iterators.
1481 Also note that the absolute values of initial_value and
1482 final_value are unimportant as only their difference is used for
1483 calculating the number of loop iterations. */
1484 *initial_value = loop_info->initial_value;
1485 *increment = loop_info->increment;
1486 *final_value = loop_info->final_value;
1488 /* Decide what mode to do these calculations in. Choose the larger
1489 of final_value's mode and initial_value's mode, or a full-word if
1490 both are constants. */
1491 *mode = GET_MODE (*final_value);
1492 if (*mode == VOIDmode)
1494 *mode = GET_MODE (*initial_value);
1495 if (*mode == VOIDmode)
1498 else if (*mode != GET_MODE (*initial_value)
1499 && (GET_MODE_SIZE (*mode)
1500 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1501 *mode = GET_MODE (*initial_value);
1504 if (loop_dump_stream)
1505 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1509 /* All pseudo-registers must be mapped to themselves. Two hard registers
1510 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1511 REGNUM, to avoid function-inlining specific conversions of these
1512 registers. All other hard regs can not be mapped because they may be
1517 init_reg_map (map, maxregnum)
1518 struct inline_remap *map;
1523 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1524 map->reg_map[i] = regno_reg_rtx[i];
1525 /* Just clear the rest of the entries. */
1526 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1527 map->reg_map[i] = 0;
1529 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1530 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1531 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1532 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1535 /* Strength-reduction will often emit code for optimized biv/givs which
1536 calculates their value in a temporary register, and then copies the result
1537 to the iv. This procedure reconstructs the pattern computing the iv;
1538 verifying that all operands are of the proper form.
1540 PATTERN must be the result of single_set.
1541 The return value is the amount that the giv is incremented by. */
1544 calculate_giv_inc (pattern, src_insn, regno)
1545 rtx pattern, src_insn;
1549 rtx increment_total = 0;
1553 /* Verify that we have an increment insn here. First check for a plus
1554 as the set source. */
1555 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1557 /* SR sometimes computes the new giv value in a temp, then copies it
1559 src_insn = PREV_INSN (src_insn);
1560 pattern = PATTERN (src_insn);
1561 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1564 /* The last insn emitted is not needed, so delete it to avoid confusing
1565 the second cse pass. This insn sets the giv unnecessarily. */
1566 delete_insn (get_last_insn ());
1569 /* Verify that we have a constant as the second operand of the plus. */
1570 increment = XEXP (SET_SRC (pattern), 1);
1571 if (GET_CODE (increment) != CONST_INT)
1573 /* SR sometimes puts the constant in a register, especially if it is
1574 too big to be an add immed operand. */
1575 src_insn = PREV_INSN (src_insn);
1576 increment = SET_SRC (PATTERN (src_insn));
1578 /* SR may have used LO_SUM to compute the constant if it is too large
1579 for a load immed operand. In this case, the constant is in operand
1580 one of the LO_SUM rtx. */
1581 if (GET_CODE (increment) == LO_SUM)
1582 increment = XEXP (increment, 1);
1584 /* Some ports store large constants in memory and add a REG_EQUAL
1585 note to the store insn. */
1586 else if (GET_CODE (increment) == MEM)
1588 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1590 increment = XEXP (note, 0);
1593 else if (GET_CODE (increment) == IOR
1594 || GET_CODE (increment) == ASHIFT
1595 || GET_CODE (increment) == PLUS)
1597 /* The rs6000 port loads some constants with IOR.
1598 The alpha port loads some constants with ASHIFT and PLUS. */
1599 rtx second_part = XEXP (increment, 1);
1600 enum rtx_code code = GET_CODE (increment);
1602 src_insn = PREV_INSN (src_insn);
1603 increment = SET_SRC (PATTERN (src_insn));
1604 /* Don't need the last insn anymore. */
1605 delete_insn (get_last_insn ());
1607 if (GET_CODE (second_part) != CONST_INT
1608 || GET_CODE (increment) != CONST_INT)
1612 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1613 else if (code == PLUS)
1614 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1616 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1619 if (GET_CODE (increment) != CONST_INT)
1622 /* The insn loading the constant into a register is no longer needed,
1624 delete_insn (get_last_insn ());
1627 if (increment_total)
1628 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1630 increment_total = increment;
1632 /* Check that the source register is the same as the register we expected
1633 to see as the source. If not, something is seriously wrong. */
1634 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1635 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1637 /* Some machines (e.g. the romp), may emit two add instructions for
1638 certain constants, so lets try looking for another add immediately
1639 before this one if we have only seen one add insn so far. */
1645 src_insn = PREV_INSN (src_insn);
1646 pattern = PATTERN (src_insn);
1648 delete_insn (get_last_insn ());
1656 return increment_total;
1659 /* Copy REG_NOTES, except for insn references, because not all insn_map
1660 entries are valid yet. We do need to copy registers now though, because
1661 the reg_map entries can change during copying. */
1664 initial_reg_note_copy (notes, map)
1666 struct inline_remap *map;
1673 copy = rtx_alloc (GET_CODE (notes));
1674 PUT_REG_NOTE_KIND (copy, REG_NOTE_KIND (notes));
1676 if (GET_CODE (notes) == EXPR_LIST)
1677 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1678 else if (GET_CODE (notes) == INSN_LIST)
1679 /* Don't substitute for these yet. */
1680 XEXP (copy, 0) = copy_rtx (XEXP (notes, 0));
1684 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1689 /* Fixup insn references in copied REG_NOTES. */
1692 final_reg_note_copy (notesp, map)
1694 struct inline_remap *map;
1700 if (GET_CODE (note) == INSN_LIST)
1702 /* Sometimes, we have a REG_WAS_0 note that points to a
1703 deleted instruction. In that case, we can just delete the
1705 if (REG_NOTE_KIND (note) == REG_WAS_0)
1707 *notesp = XEXP (note, 1);
1712 rtx insn = map->insn_map[INSN_UID (XEXP (note, 0))];
1714 /* If we failed to remap the note, something is awry. */
1718 XEXP (note, 0) = insn;
1722 notesp = &XEXP (note, 1);
1726 /* Copy each instruction in the loop, substituting from map as appropriate.
1727 This is very similar to a loop in expand_inline_function. */
1730 copy_loop_body (loop, copy_start, copy_end, map, exit_label, last_iteration,
1731 unroll_type, start_label, loop_end, insert_before,
1734 rtx copy_start, copy_end;
1735 struct inline_remap *map;
1738 enum unroll_types unroll_type;
1739 rtx start_label, loop_end, insert_before, copy_notes_from;
1741 struct loop_ivs *ivs = LOOP_IVS (loop);
1743 rtx set, tem, copy = NULL_RTX;
1744 int dest_reg_was_split, i;
1748 rtx final_label = 0;
1749 rtx giv_inc, giv_dest_reg, giv_src_reg;
1751 /* If this isn't the last iteration, then map any references to the
1752 start_label to final_label. Final label will then be emitted immediately
1753 after the end of this loop body if it was ever used.
1755 If this is the last iteration, then map references to the start_label
1757 if (! last_iteration)
1759 final_label = gen_label_rtx ();
1760 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), final_label);
1763 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1767 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1768 Else gen_sequence could return a raw pattern for a jump which we pass
1769 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1770 a variety of losing behaviors later. */
1771 emit_note (0, NOTE_INSN_DELETED);
1776 insn = NEXT_INSN (insn);
1778 map->orig_asm_operands_vector = 0;
1780 switch (GET_CODE (insn))
1783 pattern = PATTERN (insn);
1787 /* Check to see if this is a giv that has been combined with
1788 some split address givs. (Combined in the sense that
1789 `combine_givs' in loop.c has put two givs in the same register.)
1790 In this case, we must search all givs based on the same biv to
1791 find the address givs. Then split the address givs.
1792 Do this before splitting the giv, since that may map the
1793 SET_DEST to a new register. */
1795 if ((set = single_set (insn))
1796 && GET_CODE (SET_DEST (set)) == REG
1797 && addr_combined_regs[REGNO (SET_DEST (set))])
1799 struct iv_class *bl;
1800 struct induction *v, *tv;
1801 unsigned int regno = REGNO (SET_DEST (set));
1803 v = addr_combined_regs[REGNO (SET_DEST (set))];
1804 bl = REG_IV_CLASS (ivs, REGNO (v->src_reg));
1806 /* Although the giv_inc amount is not needed here, we must call
1807 calculate_giv_inc here since it might try to delete the
1808 last insn emitted. If we wait until later to call it,
1809 we might accidentally delete insns generated immediately
1810 below by emit_unrolled_add. */
1812 giv_inc = calculate_giv_inc (set, insn, regno);
1814 /* Now find all address giv's that were combined with this
1816 for (tv = bl->giv; tv; tv = tv->next_iv)
1817 if (tv->giv_type == DEST_ADDR && tv->same == v)
1821 /* If this DEST_ADDR giv was not split, then ignore it. */
1822 if (*tv->location != tv->dest_reg)
1825 /* Scale this_giv_inc if the multiplicative factors of
1826 the two givs are different. */
1827 this_giv_inc = INTVAL (giv_inc);
1828 if (tv->mult_val != v->mult_val)
1829 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1830 * INTVAL (tv->mult_val));
1832 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1833 *tv->location = tv->dest_reg;
1835 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1837 /* Must emit an insn to increment the split address
1838 giv. Add in the const_adjust field in case there
1839 was a constant eliminated from the address. */
1840 rtx value, dest_reg;
1842 /* tv->dest_reg will be either a bare register,
1843 or else a register plus a constant. */
1844 if (GET_CODE (tv->dest_reg) == REG)
1845 dest_reg = tv->dest_reg;
1847 dest_reg = XEXP (tv->dest_reg, 0);
1849 /* Check for shared address givs, and avoid
1850 incrementing the shared pseudo reg more than
1852 if (! tv->same_insn && ! tv->shared)
1854 /* tv->dest_reg may actually be a (PLUS (REG)
1855 (CONST)) here, so we must call plus_constant
1856 to add the const_adjust amount before calling
1857 emit_unrolled_add below. */
1858 value = plus_constant (tv->dest_reg,
1861 if (GET_CODE (value) == PLUS)
1863 /* The constant could be too large for an add
1864 immediate, so can't directly emit an insn
1866 emit_unrolled_add (dest_reg, XEXP (value, 0),
1871 /* Reset the giv to be just the register again, in case
1872 it is used after the set we have just emitted.
1873 We must subtract the const_adjust factor added in
1875 tv->dest_reg = plus_constant (dest_reg,
1877 *tv->location = tv->dest_reg;
1882 /* If this is a setting of a splittable variable, then determine
1883 how to split the variable, create a new set based on this split,
1884 and set up the reg_map so that later uses of the variable will
1885 use the new split variable. */
1887 dest_reg_was_split = 0;
1889 if ((set = single_set (insn))
1890 && GET_CODE (SET_DEST (set)) == REG
1891 && splittable_regs[REGNO (SET_DEST (set))])
1893 unsigned int regno = REGNO (SET_DEST (set));
1894 unsigned int src_regno;
1896 dest_reg_was_split = 1;
1898 giv_dest_reg = SET_DEST (set);
1899 giv_src_reg = giv_dest_reg;
1900 /* Compute the increment value for the giv, if it wasn't
1901 already computed above. */
1903 giv_inc = calculate_giv_inc (set, insn, regno);
1905 src_regno = REGNO (giv_src_reg);
1907 if (unroll_type == UNROLL_COMPLETELY)
1909 /* Completely unrolling the loop. Set the induction
1910 variable to a known constant value. */
1912 /* The value in splittable_regs may be an invariant
1913 value, so we must use plus_constant here. */
1914 splittable_regs[regno]
1915 = plus_constant (splittable_regs[src_regno],
1918 if (GET_CODE (splittable_regs[regno]) == PLUS)
1920 giv_src_reg = XEXP (splittable_regs[regno], 0);
1921 giv_inc = XEXP (splittable_regs[regno], 1);
1925 /* The splittable_regs value must be a REG or a
1926 CONST_INT, so put the entire value in the giv_src_reg
1928 giv_src_reg = splittable_regs[regno];
1929 giv_inc = const0_rtx;
1934 /* Partially unrolling loop. Create a new pseudo
1935 register for the iteration variable, and set it to
1936 be a constant plus the original register. Except
1937 on the last iteration, when the result has to
1938 go back into the original iteration var register. */
1940 /* Handle bivs which must be mapped to a new register
1941 when split. This happens for bivs which need their
1942 final value set before loop entry. The new register
1943 for the biv was stored in the biv's first struct
1944 induction entry by find_splittable_regs. */
1946 if (regno < ivs->n_regs
1947 && REG_IV_TYPE (ivs, regno) == BASIC_INDUCT)
1949 giv_src_reg = REG_IV_CLASS (ivs, regno)->biv->src_reg;
1950 giv_dest_reg = giv_src_reg;
1954 /* If non-reduced/final-value givs were split, then
1955 this would have to remap those givs also. See
1956 find_splittable_regs. */
1959 splittable_regs[regno]
1960 = simplify_gen_binary (PLUS, GET_MODE (giv_src_reg),
1962 splittable_regs[src_regno]);
1963 giv_inc = splittable_regs[regno];
1965 /* Now split the induction variable by changing the dest
1966 of this insn to a new register, and setting its
1967 reg_map entry to point to this new register.
1969 If this is the last iteration, and this is the last insn
1970 that will update the iv, then reuse the original dest,
1971 to ensure that the iv will have the proper value when
1972 the loop exits or repeats.
1974 Using splittable_regs_updates here like this is safe,
1975 because it can only be greater than one if all
1976 instructions modifying the iv are always executed in
1979 if (! last_iteration
1980 || (splittable_regs_updates[regno]-- != 1))
1982 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1984 map->reg_map[regno] = tem;
1985 record_base_value (REGNO (tem),
1986 giv_inc == const0_rtx
1988 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1989 giv_src_reg, giv_inc),
1993 map->reg_map[regno] = giv_src_reg;
1996 /* The constant being added could be too large for an add
1997 immediate, so can't directly emit an insn here. */
1998 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1999 copy = get_last_insn ();
2000 pattern = PATTERN (copy);
2004 pattern = copy_rtx_and_substitute (pattern, map, 0);
2005 copy = emit_insn (pattern);
2007 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2010 /* If this insn is setting CC0, it may need to look at
2011 the insn that uses CC0 to see what type of insn it is.
2012 In that case, the call to recog via validate_change will
2013 fail. So don't substitute constants here. Instead,
2014 do it when we emit the following insn.
2016 For example, see the pyr.md file. That machine has signed and
2017 unsigned compares. The compare patterns must check the
2018 following branch insn to see which what kind of compare to
2021 If the previous insn set CC0, substitute constants on it as
2023 if (sets_cc0_p (PATTERN (copy)) != 0)
2028 try_constants (cc0_insn, map);
2030 try_constants (copy, map);
2033 try_constants (copy, map);
2036 /* Make split induction variable constants `permanent' since we
2037 know there are no backward branches across iteration variable
2038 settings which would invalidate this. */
2039 if (dest_reg_was_split)
2041 int regno = REGNO (SET_DEST (set));
2043 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
2044 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
2046 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
2051 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2052 copy = emit_jump_insn (pattern);
2053 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2055 if (JUMP_LABEL (insn) == start_label && insn == copy_end
2056 && ! last_iteration)
2058 /* Update JUMP_LABEL make invert_jump work correctly. */
2059 JUMP_LABEL (copy) = get_label_from_map (map,
2061 (JUMP_LABEL (insn)));
2062 LABEL_NUSES (JUMP_LABEL (copy))++;
2064 /* This is a branch to the beginning of the loop; this is the
2065 last insn being copied; and this is not the last iteration.
2066 In this case, we want to change the original fall through
2067 case to be a branch past the end of the loop, and the
2068 original jump label case to fall_through. */
2070 if (!invert_jump (copy, exit_label, 0))
2073 rtx lab = gen_label_rtx ();
2074 /* Can't do it by reversing the jump (probably because we
2075 couldn't reverse the conditions), so emit a new
2076 jump_insn after COPY, and redirect the jump around
2078 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2079 jmp = emit_barrier_after (jmp);
2080 emit_label_after (lab, jmp);
2081 LABEL_NUSES (lab) = 0;
2082 if (!redirect_jump (copy, lab, 0))
2089 try_constants (cc0_insn, map);
2092 try_constants (copy, map);
2094 /* Set the jump label of COPY correctly to avoid problems with
2095 later passes of unroll_loop, if INSN had jump label set. */
2096 if (JUMP_LABEL (insn))
2100 /* Can't use the label_map for every insn, since this may be
2101 the backward branch, and hence the label was not mapped. */
2102 if ((set = single_set (copy)))
2104 tem = SET_SRC (set);
2105 if (GET_CODE (tem) == LABEL_REF)
2106 label = XEXP (tem, 0);
2107 else if (GET_CODE (tem) == IF_THEN_ELSE)
2109 if (XEXP (tem, 1) != pc_rtx)
2110 label = XEXP (XEXP (tem, 1), 0);
2112 label = XEXP (XEXP (tem, 2), 0);
2116 if (label && GET_CODE (label) == CODE_LABEL)
2117 JUMP_LABEL (copy) = label;
2120 /* An unrecognizable jump insn, probably the entry jump
2121 for a switch statement. This label must have been mapped,
2122 so just use the label_map to get the new jump label. */
2124 = get_label_from_map (map,
2125 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2128 /* If this is a non-local jump, then must increase the label
2129 use count so that the label will not be deleted when the
2130 original jump is deleted. */
2131 LABEL_NUSES (JUMP_LABEL (copy))++;
2133 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2134 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2136 rtx pat = PATTERN (copy);
2137 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2138 int len = XVECLEN (pat, diff_vec_p);
2141 for (i = 0; i < len; i++)
2142 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2145 /* If this used to be a conditional jump insn but whose branch
2146 direction is now known, we must do something special. */
2147 if (any_condjump_p (insn) && onlyjump_p (insn) && map->last_pc_value)
2150 /* If the previous insn set cc0 for us, delete it. */
2151 if (only_sets_cc0_p (PREV_INSN (copy)))
2152 delete_insn (PREV_INSN (copy));
2155 /* If this is now a no-op, delete it. */
2156 if (map->last_pc_value == pc_rtx)
2158 /* Don't let delete_insn delete the label referenced here,
2159 because we might possibly need it later for some other
2160 instruction in the loop. */
2161 if (JUMP_LABEL (copy))
2162 LABEL_NUSES (JUMP_LABEL (copy))++;
2164 if (JUMP_LABEL (copy))
2165 LABEL_NUSES (JUMP_LABEL (copy))--;
2169 /* Otherwise, this is unconditional jump so we must put a
2170 BARRIER after it. We could do some dead code elimination
2171 here, but jump.c will do it just as well. */
2177 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2178 copy = emit_call_insn (pattern);
2179 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2181 /* Because the USAGE information potentially contains objects other
2182 than hard registers, we need to copy it. */
2183 CALL_INSN_FUNCTION_USAGE (copy)
2184 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2189 try_constants (cc0_insn, map);
2192 try_constants (copy, map);
2194 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2195 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2196 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2200 /* If this is the loop start label, then we don't need to emit a
2201 copy of this label since no one will use it. */
2203 if (insn != start_label)
2205 copy = emit_label (get_label_from_map (map,
2206 CODE_LABEL_NUMBER (insn)));
2212 copy = emit_barrier ();
2216 /* VTOP and CONT notes are valid only before the loop exit test.
2217 If placed anywhere else, loop may generate bad code. */
2218 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2219 the associated rtl. We do not want to share the structure in
2222 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2223 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED_LABEL
2224 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2225 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2226 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2227 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2228 copy = emit_note (NOTE_SOURCE_FILE (insn),
2229 NOTE_LINE_NUMBER (insn));
2238 map->insn_map[INSN_UID (insn)] = copy;
2240 while (insn != copy_end);
2242 /* Now finish coping the REG_NOTES. */
2246 insn = NEXT_INSN (insn);
2247 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2248 || GET_CODE (insn) == CALL_INSN)
2249 && map->insn_map[INSN_UID (insn)])
2250 final_reg_note_copy (®_NOTES (map->insn_map[INSN_UID (insn)]), map);
2252 while (insn != copy_end);
2254 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2255 each of these notes here, since there may be some important ones, such as
2256 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2257 iteration, because the original notes won't be deleted.
2259 We can't use insert_before here, because when from preconditioning,
2260 insert_before points before the loop. We can't use copy_end, because
2261 there may be insns already inserted after it (which we don't want to
2262 copy) when not from preconditioning code. */
2264 if (! last_iteration)
2266 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2268 /* VTOP notes are valid only before the loop exit test.
2269 If placed anywhere else, loop may generate bad code.
2270 There is no need to test for NOTE_INSN_LOOP_CONT notes
2271 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2272 instructions before the last insn in the loop, and if the
2273 end test is that short, there will be a VTOP note between
2274 the CONT note and the test. */
2275 if (GET_CODE (insn) == NOTE
2276 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2277 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2278 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2279 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2283 if (final_label && LABEL_NUSES (final_label) > 0)
2284 emit_label (final_label);
2286 tem = gen_sequence ();
2288 loop_insn_emit_before (loop, 0, insert_before, tem);
2291 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2292 emitted. This will correctly handle the case where the increment value
2293 won't fit in the immediate field of a PLUS insns. */
2296 emit_unrolled_add (dest_reg, src_reg, increment)
2297 rtx dest_reg, src_reg, increment;
2301 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2302 dest_reg, 0, OPTAB_LIB_WIDEN);
2304 if (dest_reg != result)
2305 emit_move_insn (dest_reg, result);
2308 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2309 is a backward branch in that range that branches to somewhere between
2310 LOOP->START and INSN. Returns 0 otherwise. */
2312 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2313 In practice, this is not a problem, because this function is seldom called,
2314 and uses a negligible amount of CPU time on average. */
2317 back_branch_in_range_p (loop, insn)
2318 const struct loop *loop;
2321 rtx p, q, target_insn;
2322 rtx loop_start = loop->start;
2323 rtx loop_end = loop->end;
2324 rtx orig_loop_end = loop->end;
2326 /* Stop before we get to the backward branch at the end of the loop. */
2327 loop_end = prev_nonnote_insn (loop_end);
2328 if (GET_CODE (loop_end) == BARRIER)
2329 loop_end = PREV_INSN (loop_end);
2331 /* Check in case insn has been deleted, search forward for first non
2332 deleted insn following it. */
2333 while (INSN_DELETED_P (insn))
2334 insn = NEXT_INSN (insn);
2336 /* Check for the case where insn is the last insn in the loop. Deal
2337 with the case where INSN was a deleted loop test insn, in which case
2338 it will now be the NOTE_LOOP_END. */
2339 if (insn == loop_end || insn == orig_loop_end)
2342 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2344 if (GET_CODE (p) == JUMP_INSN)
2346 target_insn = JUMP_LABEL (p);
2348 /* Search from loop_start to insn, to see if one of them is
2349 the target_insn. We can't use INSN_LUID comparisons here,
2350 since insn may not have an LUID entry. */
2351 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2352 if (q == target_insn)
2360 /* Try to generate the simplest rtx for the expression
2361 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2365 fold_rtx_mult_add (mult1, mult2, add1, mode)
2366 rtx mult1, mult2, add1;
2367 enum machine_mode mode;
2372 /* The modes must all be the same. This should always be true. For now,
2373 check to make sure. */
2374 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2375 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2376 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2379 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2380 will be a constant. */
2381 if (GET_CODE (mult1) == CONST_INT)
2388 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2390 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2392 /* Again, put the constant second. */
2393 if (GET_CODE (add1) == CONST_INT)
2400 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2402 result = gen_rtx_PLUS (mode, add1, mult_res);
2407 /* Searches the list of induction struct's for the biv BL, to try to calculate
2408 the total increment value for one iteration of the loop as a constant.
2410 Returns the increment value as an rtx, simplified as much as possible,
2411 if it can be calculated. Otherwise, returns 0. */
2414 biv_total_increment (bl)
2415 const struct iv_class *bl;
2417 struct induction *v;
2420 /* For increment, must check every instruction that sets it. Each
2421 instruction must be executed only once each time through the loop.
2422 To verify this, we check that the insn is always executed, and that
2423 there are no backward branches after the insn that branch to before it.
2424 Also, the insn must have a mult_val of one (to make sure it really is
2427 result = const0_rtx;
2428 for (v = bl->biv; v; v = v->next_iv)
2430 if (v->always_computable && v->mult_val == const1_rtx
2431 && ! v->maybe_multiple)
2432 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2440 /* For each biv and giv, determine whether it can be safely split into
2441 a different variable for each unrolled copy of the loop body. If it
2442 is safe to split, then indicate that by saving some useful info
2443 in the splittable_regs array.
2445 If the loop is being completely unrolled, then splittable_regs will hold
2446 the current value of the induction variable while the loop is unrolled.
2447 It must be set to the initial value of the induction variable here.
2448 Otherwise, splittable_regs will hold the difference between the current
2449 value of the induction variable and the value the induction variable had
2450 at the top of the loop. It must be set to the value 0 here.
2452 Returns the total number of instructions that set registers that are
2455 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2456 constant values are unnecessary, since we can easily calculate increment
2457 values in this case even if nothing is constant. The increment value
2458 should not involve a multiply however. */
2460 /* ?? Even if the biv/giv increment values aren't constant, it may still
2461 be beneficial to split the variable if the loop is only unrolled a few
2462 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2465 find_splittable_regs (loop, unroll_type, unroll_number)
2466 const struct loop *loop;
2467 enum unroll_types unroll_type;
2470 struct loop_ivs *ivs = LOOP_IVS (loop);
2471 struct iv_class *bl;
2472 struct induction *v;
2474 rtx biv_final_value;
2478 for (bl = ivs->list; bl; bl = bl->next)
2480 /* Biv_total_increment must return a constant value,
2481 otherwise we can not calculate the split values. */
2483 increment = biv_total_increment (bl);
2484 if (! increment || GET_CODE (increment) != CONST_INT)
2487 /* The loop must be unrolled completely, or else have a known number
2488 of iterations and only one exit, or else the biv must be dead
2489 outside the loop, or else the final value must be known. Otherwise,
2490 it is unsafe to split the biv since it may not have the proper
2491 value on loop exit. */
2493 /* loop_number_exit_count is non-zero if the loop has an exit other than
2494 a fall through at the end. */
2497 biv_final_value = 0;
2498 if (unroll_type != UNROLL_COMPLETELY
2499 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2500 && (REGNO_LAST_LUID (bl->regno) >= INSN_LUID (loop->end)
2502 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2503 || (REGNO_FIRST_LUID (bl->regno)
2504 < INSN_LUID (bl->init_insn))
2505 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2506 && ! (biv_final_value = final_biv_value (loop, bl)))
2509 /* If any of the insns setting the BIV don't do so with a simple
2510 PLUS, we don't know how to split it. */
2511 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2512 if ((tem = single_set (v->insn)) == 0
2513 || GET_CODE (SET_DEST (tem)) != REG
2514 || REGNO (SET_DEST (tem)) != bl->regno
2515 || GET_CODE (SET_SRC (tem)) != PLUS)
2518 /* If final value is non-zero, then must emit an instruction which sets
2519 the value of the biv to the proper value. This is done after
2520 handling all of the givs, since some of them may need to use the
2521 biv's value in their initialization code. */
2523 /* This biv is splittable. If completely unrolling the loop, save
2524 the biv's initial value. Otherwise, save the constant zero. */
2526 if (biv_splittable == 1)
2528 if (unroll_type == UNROLL_COMPLETELY)
2530 /* If the initial value of the biv is itself (i.e. it is too
2531 complicated for strength_reduce to compute), or is a hard
2532 register, or it isn't invariant, then we must create a new
2533 pseudo reg to hold the initial value of the biv. */
2535 if (GET_CODE (bl->initial_value) == REG
2536 && (REGNO (bl->initial_value) == bl->regno
2537 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2538 || ! loop_invariant_p (loop, bl->initial_value)))
2540 rtx tem = gen_reg_rtx (bl->biv->mode);
2542 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2543 loop_insn_hoist (loop,
2544 gen_move_insn (tem, bl->biv->src_reg));
2546 if (loop_dump_stream)
2547 fprintf (loop_dump_stream,
2548 "Biv %d initial value remapped to %d.\n",
2549 bl->regno, REGNO (tem));
2551 splittable_regs[bl->regno] = tem;
2554 splittable_regs[bl->regno] = bl->initial_value;
2557 splittable_regs[bl->regno] = const0_rtx;
2559 /* Save the number of instructions that modify the biv, so that
2560 we can treat the last one specially. */
2562 splittable_regs_updates[bl->regno] = bl->biv_count;
2563 result += bl->biv_count;
2565 if (loop_dump_stream)
2566 fprintf (loop_dump_stream,
2567 "Biv %d safe to split.\n", bl->regno);
2570 /* Check every giv that depends on this biv to see whether it is
2571 splittable also. Even if the biv isn't splittable, givs which
2572 depend on it may be splittable if the biv is live outside the
2573 loop, and the givs aren't. */
2575 result += find_splittable_givs (loop, bl, unroll_type, increment,
2578 /* If final value is non-zero, then must emit an instruction which sets
2579 the value of the biv to the proper value. This is done after
2580 handling all of the givs, since some of them may need to use the
2581 biv's value in their initialization code. */
2582 if (biv_final_value)
2584 /* If the loop has multiple exits, emit the insns before the
2585 loop to ensure that it will always be executed no matter
2586 how the loop exits. Otherwise emit the insn after the loop,
2587 since this is slightly more efficient. */
2588 if (! loop->exit_count)
2589 loop_insn_sink (loop, gen_move_insn (bl->biv->src_reg,
2593 /* Create a new register to hold the value of the biv, and then
2594 set the biv to its final value before the loop start. The biv
2595 is set to its final value before loop start to ensure that
2596 this insn will always be executed, no matter how the loop
2598 rtx tem = gen_reg_rtx (bl->biv->mode);
2599 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2601 loop_insn_hoist (loop, gen_move_insn (tem, bl->biv->src_reg));
2602 loop_insn_hoist (loop, gen_move_insn (bl->biv->src_reg,
2605 if (loop_dump_stream)
2606 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2607 REGNO (bl->biv->src_reg), REGNO (tem));
2609 /* Set up the mapping from the original biv register to the new
2611 bl->biv->src_reg = tem;
2618 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2619 for the instruction that is using it. Do not make any changes to that
2623 verify_addresses (v, giv_inc, unroll_number)
2624 struct induction *v;
2629 rtx orig_addr = *v->location;
2630 rtx last_addr = plus_constant (v->dest_reg,
2631 INTVAL (giv_inc) * (unroll_number - 1));
2633 /* First check to see if either address would fail. Handle the fact
2634 that we have may have a match_dup. */
2635 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2636 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2639 /* Now put things back the way they were before. This should always
2641 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2647 /* For every giv based on the biv BL, check to determine whether it is
2648 splittable. This is a subroutine to find_splittable_regs ().
2650 Return the number of instructions that set splittable registers. */
2653 find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
2654 const struct loop *loop;
2655 struct iv_class *bl;
2656 enum unroll_types unroll_type;
2660 struct loop_ivs *ivs = LOOP_IVS (loop);
2661 struct induction *v, *v2;
2666 /* Scan the list of givs, and set the same_insn field when there are
2667 multiple identical givs in the same insn. */
2668 for (v = bl->giv; v; v = v->next_iv)
2669 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2670 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2674 for (v = bl->giv; v; v = v->next_iv)
2678 /* Only split the giv if it has already been reduced, or if the loop is
2679 being completely unrolled. */
2680 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2683 /* The giv can be split if the insn that sets the giv is executed once
2684 and only once on every iteration of the loop. */
2685 /* An address giv can always be split. v->insn is just a use not a set,
2686 and hence it does not matter whether it is always executed. All that
2687 matters is that all the biv increments are always executed, and we
2688 won't reach here if they aren't. */
2689 if (v->giv_type != DEST_ADDR
2690 && (! v->always_computable
2691 || back_branch_in_range_p (loop, v->insn)))
2694 /* The giv increment value must be a constant. */
2695 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2697 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2700 /* The loop must be unrolled completely, or else have a known number of
2701 iterations and only one exit, or else the giv must be dead outside
2702 the loop, or else the final value of the giv must be known.
2703 Otherwise, it is not safe to split the giv since it may not have the
2704 proper value on loop exit. */
2706 /* The used outside loop test will fail for DEST_ADDR givs. They are
2707 never used outside the loop anyways, so it is always safe to split a
2711 if (unroll_type != UNROLL_COMPLETELY
2712 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2713 && v->giv_type != DEST_ADDR
2714 /* The next part is true if the pseudo is used outside the loop.
2715 We assume that this is true for any pseudo created after loop
2716 starts, because we don't have a reg_n_info entry for them. */
2717 && (REGNO (v->dest_reg) >= max_reg_before_loop
2718 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2719 /* Check for the case where the pseudo is set by a shift/add
2720 sequence, in which case the first insn setting the pseudo
2721 is the first insn of the shift/add sequence. */
2722 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2723 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2724 != INSN_UID (XEXP (tem, 0)))))
2725 /* Line above always fails if INSN was moved by loop opt. */
2726 || (REGNO_LAST_LUID (REGNO (v->dest_reg))
2727 >= INSN_LUID (loop->end)))
2728 && ! (final_value = v->final_value))
2732 /* Currently, non-reduced/final-value givs are never split. */
2733 /* Should emit insns after the loop if possible, as the biv final value
2736 /* If the final value is non-zero, and the giv has not been reduced,
2737 then must emit an instruction to set the final value. */
2738 if (final_value && !v->new_reg)
2740 /* Create a new register to hold the value of the giv, and then set
2741 the giv to its final value before the loop start. The giv is set
2742 to its final value before loop start to ensure that this insn
2743 will always be executed, no matter how we exit. */
2744 tem = gen_reg_rtx (v->mode);
2745 loop_insn_hoist (loop, gen_move_insn (tem, v->dest_reg));
2746 loop_insn_hoist (loop, gen_move_insn (v->dest_reg, final_value));
2748 if (loop_dump_stream)
2749 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2750 REGNO (v->dest_reg), REGNO (tem));
2756 /* This giv is splittable. If completely unrolling the loop, save the
2757 giv's initial value. Otherwise, save the constant zero for it. */
2759 if (unroll_type == UNROLL_COMPLETELY)
2761 /* It is not safe to use bl->initial_value here, because it may not
2762 be invariant. It is safe to use the initial value stored in
2763 the splittable_regs array if it is set. In rare cases, it won't
2764 be set, so then we do exactly the same thing as
2765 find_splittable_regs does to get a safe value. */
2766 rtx biv_initial_value;
2768 if (splittable_regs[bl->regno])
2769 biv_initial_value = splittable_regs[bl->regno];
2770 else if (GET_CODE (bl->initial_value) != REG
2771 || (REGNO (bl->initial_value) != bl->regno
2772 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2773 biv_initial_value = bl->initial_value;
2776 rtx tem = gen_reg_rtx (bl->biv->mode);
2778 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2779 loop_insn_hoist (loop, gen_move_insn (tem, bl->biv->src_reg));
2780 biv_initial_value = tem;
2782 biv_initial_value = extend_value_for_giv (v, biv_initial_value);
2783 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2784 v->add_val, v->mode);
2791 /* If a giv was combined with another giv, then we can only split
2792 this giv if the giv it was combined with was reduced. This
2793 is because the value of v->new_reg is meaningless in this
2795 if (v->same && ! v->same->new_reg)
2797 if (loop_dump_stream)
2798 fprintf (loop_dump_stream,
2799 "giv combined with unreduced giv not split.\n");
2802 /* If the giv is an address destination, it could be something other
2803 than a simple register, these have to be treated differently. */
2804 else if (v->giv_type == DEST_REG)
2806 /* If value is not a constant, register, or register plus
2807 constant, then compute its value into a register before
2808 loop start. This prevents invalid rtx sharing, and should
2809 generate better code. We can use bl->initial_value here
2810 instead of splittable_regs[bl->regno] because this code
2811 is going before the loop start. */
2812 if (unroll_type == UNROLL_COMPLETELY
2813 && GET_CODE (value) != CONST_INT
2814 && GET_CODE (value) != REG
2815 && (GET_CODE (value) != PLUS
2816 || GET_CODE (XEXP (value, 0)) != REG
2817 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2819 rtx tem = gen_reg_rtx (v->mode);
2820 record_base_value (REGNO (tem), v->add_val, 0);
2821 loop_iv_add_mult_hoist (loop, bl->initial_value, v->mult_val,
2826 splittable_regs[REGNO (v->new_reg)] = value;
2830 /* Splitting address givs is useful since it will often allow us
2831 to eliminate some increment insns for the base giv as
2834 /* If the addr giv is combined with a dest_reg giv, then all
2835 references to that dest reg will be remapped, which is NOT
2836 what we want for split addr regs. We always create a new
2837 register for the split addr giv, just to be safe. */
2839 /* If we have multiple identical address givs within a
2840 single instruction, then use a single pseudo reg for
2841 both. This is necessary in case one is a match_dup
2844 v->const_adjust = 0;
2848 v->dest_reg = v->same_insn->dest_reg;
2849 if (loop_dump_stream)
2850 fprintf (loop_dump_stream,
2851 "Sharing address givs in insn %d\n",
2852 INSN_UID (v->insn));
2854 /* If multiple address GIVs have been combined with the
2855 same dest_reg GIV, do not create a new register for
2857 else if (unroll_type != UNROLL_COMPLETELY
2858 && v->giv_type == DEST_ADDR
2859 && v->same && v->same->giv_type == DEST_ADDR
2860 && v->same->unrolled
2861 /* combine_givs_p may return true for some cases
2862 where the add and mult values are not equal.
2863 To share a register here, the values must be
2865 && rtx_equal_p (v->same->mult_val, v->mult_val)
2866 && rtx_equal_p (v->same->add_val, v->add_val)
2867 /* If the memory references have different modes,
2868 then the address may not be valid and we must
2869 not share registers. */
2870 && verify_addresses (v, giv_inc, unroll_number))
2872 v->dest_reg = v->same->dest_reg;
2875 else if (unroll_type != UNROLL_COMPLETELY)
2877 /* If not completely unrolling the loop, then create a new
2878 register to hold the split value of the DEST_ADDR giv.
2879 Emit insn to initialize its value before loop start. */
2881 rtx tem = gen_reg_rtx (v->mode);
2882 struct induction *same = v->same;
2883 rtx new_reg = v->new_reg;
2884 record_base_value (REGNO (tem), v->add_val, 0);
2886 /* If the address giv has a constant in its new_reg value,
2887 then this constant can be pulled out and put in value,
2888 instead of being part of the initialization code. */
2890 if (GET_CODE (new_reg) == PLUS
2891 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
2894 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
2896 /* Only succeed if this will give valid addresses.
2897 Try to validate both the first and the last
2898 address resulting from loop unrolling, if
2899 one fails, then can't do const elim here. */
2900 if (verify_addresses (v, giv_inc, unroll_number))
2902 /* Save the negative of the eliminated const, so
2903 that we can calculate the dest_reg's increment
2905 v->const_adjust = -INTVAL (XEXP (new_reg, 1));
2907 new_reg = XEXP (new_reg, 0);
2908 if (loop_dump_stream)
2909 fprintf (loop_dump_stream,
2910 "Eliminating constant from giv %d\n",
2919 /* If the address hasn't been checked for validity yet, do so
2920 now, and fail completely if either the first or the last
2921 unrolled copy of the address is not a valid address
2922 for the instruction that uses it. */
2923 if (v->dest_reg == tem
2924 && ! verify_addresses (v, giv_inc, unroll_number))
2926 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2927 if (v2->same_insn == v)
2930 if (loop_dump_stream)
2931 fprintf (loop_dump_stream,
2932 "Invalid address for giv at insn %d\n",
2933 INSN_UID (v->insn));
2937 v->new_reg = new_reg;
2940 /* We set this after the address check, to guarantee that
2941 the register will be initialized. */
2944 /* To initialize the new register, just move the value of
2945 new_reg into it. This is not guaranteed to give a valid
2946 instruction on machines with complex addressing modes.
2947 If we can't recognize it, then delete it and emit insns
2948 to calculate the value from scratch. */
2949 loop_insn_hoist (loop, gen_rtx_SET (VOIDmode, tem,
2950 copy_rtx (v->new_reg)));
2951 if (recog_memoized (PREV_INSN (loop->start)) < 0)
2955 /* We can't use bl->initial_value to compute the initial
2956 value, because the loop may have been preconditioned.
2957 We must calculate it from NEW_REG. */
2958 delete_insn (PREV_INSN (loop->start));
2961 ret = force_operand (v->new_reg, tem);
2963 emit_move_insn (tem, ret);
2964 sequence = gen_sequence ();
2966 loop_insn_hoist (loop, sequence);
2968 if (loop_dump_stream)
2969 fprintf (loop_dump_stream,
2970 "Invalid init insn, rewritten.\n");
2975 v->dest_reg = value;
2977 /* Check the resulting address for validity, and fail
2978 if the resulting address would be invalid. */
2979 if (! verify_addresses (v, giv_inc, unroll_number))
2981 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2982 if (v2->same_insn == v)
2985 if (loop_dump_stream)
2986 fprintf (loop_dump_stream,
2987 "Invalid address for giv at insn %d\n",
2988 INSN_UID (v->insn));
2993 /* Store the value of dest_reg into the insn. This sharing
2994 will not be a problem as this insn will always be copied
2997 *v->location = v->dest_reg;
2999 /* If this address giv is combined with a dest reg giv, then
3000 save the base giv's induction pointer so that we will be
3001 able to handle this address giv properly. The base giv
3002 itself does not have to be splittable. */
3004 if (v->same && v->same->giv_type == DEST_REG)
3005 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3007 if (GET_CODE (v->new_reg) == REG)
3009 /* This giv maybe hasn't been combined with any others.
3010 Make sure that it's giv is marked as splittable here. */
3012 splittable_regs[REGNO (v->new_reg)] = value;
3014 /* Make it appear to depend upon itself, so that the
3015 giv will be properly split in the main loop above. */
3019 addr_combined_regs[REGNO (v->new_reg)] = v;
3023 if (loop_dump_stream)
3024 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3030 /* Currently, unreduced giv's can't be split. This is not too much
3031 of a problem since unreduced giv's are not live across loop
3032 iterations anyways. When unrolling a loop completely though,
3033 it makes sense to reduce&split givs when possible, as this will
3034 result in simpler instructions, and will not require that a reg
3035 be live across loop iterations. */
3037 splittable_regs[REGNO (v->dest_reg)] = value;
3038 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3039 REGNO (v->dest_reg), INSN_UID (v->insn));
3045 /* Unreduced givs are only updated once by definition. Reduced givs
3046 are updated as many times as their biv is. Mark it so if this is
3047 a splittable register. Don't need to do anything for address givs
3048 where this may not be a register. */
3050 if (GET_CODE (v->new_reg) == REG)
3054 count = REG_IV_CLASS (ivs, REGNO (v->src_reg))->biv_count;
3056 splittable_regs_updates[REGNO (v->new_reg)] = count;
3061 if (loop_dump_stream)
3065 if (GET_CODE (v->dest_reg) == CONST_INT)
3067 else if (GET_CODE (v->dest_reg) != REG)
3068 regnum = REGNO (XEXP (v->dest_reg, 0));
3070 regnum = REGNO (v->dest_reg);
3071 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3072 regnum, INSN_UID (v->insn));
3079 /* Try to prove that the register is dead after the loop exits. Trace every
3080 loop exit looking for an insn that will always be executed, which sets
3081 the register to some value, and appears before the first use of the register
3082 is found. If successful, then return 1, otherwise return 0. */
3084 /* ?? Could be made more intelligent in the handling of jumps, so that
3085 it can search past if statements and other similar structures. */
3088 reg_dead_after_loop (loop, reg)
3089 const struct loop *loop;
3095 int label_count = 0;
3097 /* In addition to checking all exits of this loop, we must also check
3098 all exits of inner nested loops that would exit this loop. We don't
3099 have any way to identify those, so we just give up if there are any
3100 such inner loop exits. */
3102 for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
3105 if (label_count != loop->exit_count)
3108 /* HACK: Must also search the loop fall through exit, create a label_ref
3109 here which points to the loop->end, and append the loop_number_exit_labels
3111 label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
3112 LABEL_NEXTREF (label) = loop->exit_labels;
3114 for (; label; label = LABEL_NEXTREF (label))
3116 /* Succeed if find an insn which sets the biv or if reach end of
3117 function. Fail if find an insn that uses the biv, or if come to
3118 a conditional jump. */
3120 insn = NEXT_INSN (XEXP (label, 0));
3123 code = GET_CODE (insn);
3124 if (GET_RTX_CLASS (code) == 'i')
3128 if (reg_referenced_p (reg, PATTERN (insn)))
3131 set = single_set (insn);
3132 if (set && rtx_equal_p (SET_DEST (set), reg))
3136 if (code == JUMP_INSN)
3138 if (GET_CODE (PATTERN (insn)) == RETURN)
3140 else if (!any_uncondjump_p (insn)
3141 /* Prevent infinite loop following infinite loops. */
3142 || jump_count++ > 20)
3145 insn = JUMP_LABEL (insn);
3148 insn = NEXT_INSN (insn);
3152 /* Success, the register is dead on all loop exits. */
3156 /* Try to calculate the final value of the biv, the value it will have at
3157 the end of the loop. If we can do it, return that value. */
3160 final_biv_value (loop, bl)
3161 const struct loop *loop;
3162 struct iv_class *bl;
3164 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3167 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3169 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3172 /* The final value for reversed bivs must be calculated differently than
3173 for ordinary bivs. In this case, there is already an insn after the
3174 loop which sets this biv's final value (if necessary), and there are
3175 no other loop exits, so we can return any value. */
3178 if (loop_dump_stream)
3179 fprintf (loop_dump_stream,
3180 "Final biv value for %d, reversed biv.\n", bl->regno);
3185 /* Try to calculate the final value as initial value + (number of iterations
3186 * increment). For this to work, increment must be invariant, the only
3187 exit from the loop must be the fall through at the bottom (otherwise
3188 it may not have its final value when the loop exits), and the initial
3189 value of the biv must be invariant. */
3191 if (n_iterations != 0
3192 && ! loop->exit_count
3193 && loop_invariant_p (loop, bl->initial_value))
3195 increment = biv_total_increment (bl);
3197 if (increment && loop_invariant_p (loop, increment))
3199 /* Can calculate the loop exit value, emit insns after loop
3200 end to calculate this value into a temporary register in
3201 case it is needed later. */
3203 tem = gen_reg_rtx (bl->biv->mode);
3204 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3205 loop_iv_add_mult_sink (loop, increment, GEN_INT (n_iterations),
3206 bl->initial_value, tem);
3208 if (loop_dump_stream)
3209 fprintf (loop_dump_stream,
3210 "Final biv value for %d, calculated.\n", bl->regno);
3216 /* Check to see if the biv is dead at all loop exits. */
3217 if (reg_dead_after_loop (loop, bl->biv->src_reg))
3219 if (loop_dump_stream)
3220 fprintf (loop_dump_stream,
3221 "Final biv value for %d, biv dead after loop exit.\n",
3230 /* Try to calculate the final value of the giv, the value it will have at
3231 the end of the loop. If we can do it, return that value. */
3234 final_giv_value (loop, v)
3235 const struct loop *loop;
3236 struct induction *v;
3238 struct loop_ivs *ivs = LOOP_IVS (loop);
3239 struct iv_class *bl;
3243 rtx loop_end = loop->end;
3244 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3246 bl = REG_IV_CLASS (ivs, REGNO (v->src_reg));
3248 /* The final value for givs which depend on reversed bivs must be calculated
3249 differently than for ordinary givs. In this case, there is already an
3250 insn after the loop which sets this giv's final value (if necessary),
3251 and there are no other loop exits, so we can return any value. */
3254 if (loop_dump_stream)
3255 fprintf (loop_dump_stream,
3256 "Final giv value for %d, depends on reversed biv\n",
3257 REGNO (v->dest_reg));
3261 /* Try to calculate the final value as a function of the biv it depends
3262 upon. The only exit from the loop must be the fall through at the bottom
3263 (otherwise it may not have its final value when the loop exits). */
3265 /* ??? Can calculate the final giv value by subtracting off the
3266 extra biv increments times the giv's mult_val. The loop must have
3267 only one exit for this to work, but the loop iterations does not need
3270 if (n_iterations != 0
3271 && ! loop->exit_count)
3273 /* ?? It is tempting to use the biv's value here since these insns will
3274 be put after the loop, and hence the biv will have its final value
3275 then. However, this fails if the biv is subsequently eliminated.
3276 Perhaps determine whether biv's are eliminable before trying to
3277 determine whether giv's are replaceable so that we can use the
3278 biv value here if it is not eliminable. */
3280 /* We are emitting code after the end of the loop, so we must make
3281 sure that bl->initial_value is still valid then. It will still
3282 be valid if it is invariant. */
3284 increment = biv_total_increment (bl);
3286 if (increment && loop_invariant_p (loop, increment)
3287 && loop_invariant_p (loop, bl->initial_value))
3289 /* Can calculate the loop exit value of its biv as
3290 (n_iterations * increment) + initial_value */
3292 /* The loop exit value of the giv is then
3293 (final_biv_value - extra increments) * mult_val + add_val.
3294 The extra increments are any increments to the biv which
3295 occur in the loop after the giv's value is calculated.
3296 We must search from the insn that sets the giv to the end
3297 of the loop to calculate this value. */
3299 /* Put the final biv value in tem. */
3300 tem = gen_reg_rtx (v->mode);
3301 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3302 loop_iv_add_mult_sink (loop, extend_value_for_giv (v, increment),
3303 GEN_INT (n_iterations),
3304 extend_value_for_giv (v, bl->initial_value),
3307 /* Subtract off extra increments as we find them. */
3308 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3309 insn = NEXT_INSN (insn))
3311 struct induction *biv;
3313 for (biv = bl->biv; biv; biv = biv->next_iv)
3314 if (biv->insn == insn)
3317 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3318 biv->add_val, NULL_RTX, 0,
3320 seq = gen_sequence ();
3322 loop_insn_sink (loop, seq);
3326 /* Now calculate the giv's final value. */
3327 loop_iv_add_mult_sink (loop, tem, v->mult_val, v->add_val, tem);
3329 if (loop_dump_stream)
3330 fprintf (loop_dump_stream,
3331 "Final giv value for %d, calc from biv's value.\n",
3332 REGNO (v->dest_reg));
3338 /* Replaceable giv's should never reach here. */
3342 /* Check to see if the biv is dead at all loop exits. */
3343 if (reg_dead_after_loop (loop, v->dest_reg))
3345 if (loop_dump_stream)
3346 fprintf (loop_dump_stream,
3347 "Final giv value for %d, giv dead after loop exit.\n",
3348 REGNO (v->dest_reg));
3356 /* Look back before LOOP->START for then insn that sets REG and return
3357 the equivalent constant if there is a REG_EQUAL note otherwise just
3358 the SET_SRC of REG. */
3361 loop_find_equiv_value (loop, reg)
3362 const struct loop *loop;
3365 rtx loop_start = loop->start;
3370 for (insn = PREV_INSN (loop_start); insn; insn = PREV_INSN (insn))
3372 if (GET_CODE (insn) == CODE_LABEL)
3375 else if (INSN_P (insn) && reg_set_p (reg, insn))
3377 /* We found the last insn before the loop that sets the register.
3378 If it sets the entire register, and has a REG_EQUAL note,
3379 then use the value of the REG_EQUAL note. */
3380 if ((set = single_set (insn))
3381 && (SET_DEST (set) == reg))
3383 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3385 /* Only use the REG_EQUAL note if it is a constant.
3386 Other things, divide in particular, will cause
3387 problems later if we use them. */
3388 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3389 && CONSTANT_P (XEXP (note, 0)))
3390 ret = XEXP (note, 0);
3392 ret = SET_SRC (set);
3394 /* We cannot do this if it changes between the
3395 assignment and loop start though. */
3396 if (modified_between_p (ret, insn, loop_start))
3405 /* Return a simplified rtx for the expression OP - REG.
3407 REG must appear in OP, and OP must be a register or the sum of a register
3410 Thus, the return value must be const0_rtx or the second term.
3412 The caller is responsible for verifying that REG appears in OP and OP has
3416 subtract_reg_term (op, reg)
3421 if (GET_CODE (op) == PLUS)
3423 if (XEXP (op, 0) == reg)
3424 return XEXP (op, 1);
3425 else if (XEXP (op, 1) == reg)
3426 return XEXP (op, 0);
3428 /* OP does not contain REG as a term. */
3432 /* Find and return register term common to both expressions OP0 and
3433 OP1 or NULL_RTX if no such term exists. Each expression must be a
3434 REG or a PLUS of a REG. */
3437 find_common_reg_term (op0, op1)
3440 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3441 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3448 if (GET_CODE (op0) == PLUS)
3449 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3451 op01 = const0_rtx, op00 = op0;
3453 if (GET_CODE (op1) == PLUS)
3454 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3456 op11 = const0_rtx, op10 = op1;
3458 /* Find and return common register term if present. */
3459 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3461 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3465 /* No common register term found. */
3469 /* Determine the loop iterator and calculate the number of loop
3470 iterations. Returns the exact number of loop iterations if it can
3471 be calculated, otherwise returns zero. */
3473 unsigned HOST_WIDE_INT
3474 loop_iterations (loop)
3477 struct loop_info *loop_info = LOOP_INFO (loop);
3478 struct loop_ivs *ivs = LOOP_IVS (loop);
3479 rtx comparison, comparison_value;
3480 rtx iteration_var, initial_value, increment, final_value;
3481 enum rtx_code comparison_code;
3483 unsigned HOST_WIDE_INT abs_inc;
3484 unsigned HOST_WIDE_INT abs_diff;
3487 int unsigned_p, compare_dir, final_larger;
3490 struct iv_class *bl;
3492 loop_info->n_iterations = 0;
3493 loop_info->initial_value = 0;
3494 loop_info->initial_equiv_value = 0;
3495 loop_info->comparison_value = 0;
3496 loop_info->final_value = 0;
3497 loop_info->final_equiv_value = 0;
3498 loop_info->increment = 0;
3499 loop_info->iteration_var = 0;
3500 loop_info->unroll_number = 1;
3503 /* We used to use prev_nonnote_insn here, but that fails because it might
3504 accidentally get the branch for a contained loop if the branch for this
3505 loop was deleted. We can only trust branches immediately before the
3507 last_loop_insn = PREV_INSN (loop->end);
3509 /* ??? We should probably try harder to find the jump insn
3510 at the end of the loop. The following code assumes that
3511 the last loop insn is a jump to the top of the loop. */
3512 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3514 if (loop_dump_stream)
3515 fprintf (loop_dump_stream,
3516 "Loop iterations: No final conditional branch found.\n");
3520 /* If there is a more than a single jump to the top of the loop
3521 we cannot (easily) determine the iteration count. */
3522 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3524 if (loop_dump_stream)
3525 fprintf (loop_dump_stream,
3526 "Loop iterations: Loop has multiple back edges.\n");
3530 /* Find the iteration variable. If the last insn is a conditional
3531 branch, and the insn before tests a register value, make that the
3532 iteration variable. */
3534 comparison = get_condition_for_loop (loop, last_loop_insn);
3535 if (comparison == 0)
3537 if (loop_dump_stream)
3538 fprintf (loop_dump_stream,
3539 "Loop iterations: No final comparison found.\n");
3543 /* ??? Get_condition may switch position of induction variable and
3544 invariant register when it canonicalizes the comparison. */
3546 comparison_code = GET_CODE (comparison);
3547 iteration_var = XEXP (comparison, 0);
3548 comparison_value = XEXP (comparison, 1);
3550 if (GET_CODE (iteration_var) != REG)
3552 if (loop_dump_stream)
3553 fprintf (loop_dump_stream,
3554 "Loop iterations: Comparison not against register.\n");
3558 /* The only new registers that are created before loop iterations
3559 are givs made from biv increments or registers created by
3560 load_mems. In the latter case, it is possible that try_copy_prop
3561 will propagate a new pseudo into the old iteration register but
3562 this will be marked by having the REG_USERVAR_P bit set. */
3564 if ((unsigned) REGNO (iteration_var) >= ivs->n_regs
3565 && ! REG_USERVAR_P (iteration_var))
3568 /* Determine the initial value of the iteration variable, and the amount
3569 that it is incremented each loop. Use the tables constructed by
3570 the strength reduction pass to calculate these values. */
3572 /* Clear the result values, in case no answer can be found. */
3576 /* The iteration variable can be either a giv or a biv. Check to see
3577 which it is, and compute the variable's initial value, and increment
3578 value if possible. */
3580 /* If this is a new register, can't handle it since we don't have any
3581 reg_iv_type entry for it. */
3582 if ((unsigned) REGNO (iteration_var) >= ivs->n_regs)
3584 if (loop_dump_stream)
3585 fprintf (loop_dump_stream,
3586 "Loop iterations: No reg_iv_type entry for iteration var.\n");
3590 /* Reject iteration variables larger than the host wide int size, since they
3591 could result in a number of iterations greater than the range of our
3592 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
3593 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
3594 > HOST_BITS_PER_WIDE_INT))
3596 if (loop_dump_stream)
3597 fprintf (loop_dump_stream,
3598 "Loop iterations: Iteration var rejected because mode too large.\n");
3601 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
3603 if (loop_dump_stream)
3604 fprintf (loop_dump_stream,
3605 "Loop iterations: Iteration var not an integer.\n");
3608 else if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == BASIC_INDUCT)
3610 if (REGNO (iteration_var) >= ivs->n_regs)
3613 /* Grab initial value, only useful if it is a constant. */
3614 bl = REG_IV_CLASS (ivs, REGNO (iteration_var));
3615 initial_value = bl->initial_value;
3616 if (!bl->biv->always_executed || bl->biv->maybe_multiple)
3618 if (loop_dump_stream)
3619 fprintf (loop_dump_stream,
3620 "Loop iterations: Basic induction var not set once in each iteration.\n");
3624 increment = biv_total_increment (bl);
3626 else if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == GENERAL_INDUCT)
3628 HOST_WIDE_INT offset = 0;
3629 struct induction *v = REG_IV_INFO (ivs, REGNO (iteration_var));
3630 rtx biv_initial_value;
3632 if (REGNO (v->src_reg) >= ivs->n_regs)
3635 if (!v->always_executed || v->maybe_multiple)
3637 if (loop_dump_stream)
3638 fprintf (loop_dump_stream,
3639 "Loop iterations: General induction var not set once in each iteration.\n");
3643 bl = REG_IV_CLASS (ivs, REGNO (v->src_reg));
3645 /* Increment value is mult_val times the increment value of the biv. */
3647 increment = biv_total_increment (bl);
3650 struct induction *biv_inc;
3652 increment = fold_rtx_mult_add (v->mult_val,
3653 extend_value_for_giv (v, increment),
3654 const0_rtx, v->mode);
3655 /* The caller assumes that one full increment has occured at the
3656 first loop test. But that's not true when the biv is incremented
3657 after the giv is set (which is the usual case), e.g.:
3658 i = 6; do {;} while (i++ < 9) .
3659 Therefore, we bias the initial value by subtracting the amount of
3660 the increment that occurs between the giv set and the giv test. */
3661 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
3663 if (loop_insn_first_p (v->insn, biv_inc->insn))
3664 offset -= INTVAL (biv_inc->add_val);
3667 if (loop_dump_stream)
3668 fprintf (loop_dump_stream,
3669 "Loop iterations: Giv iterator, initial value bias %ld.\n",
3672 /* Initial value is mult_val times the biv's initial value plus
3673 add_val. Only useful if it is a constant. */
3674 biv_initial_value = extend_value_for_giv (v, bl->initial_value);
3676 = fold_rtx_mult_add (v->mult_val,
3677 plus_constant (biv_initial_value, offset),
3678 v->add_val, v->mode);
3682 if (loop_dump_stream)
3683 fprintf (loop_dump_stream,
3684 "Loop iterations: Not basic or general induction var.\n");
3688 if (initial_value == 0)
3693 switch (comparison_code)
3708 /* Cannot determine loop iterations with this case. */
3727 /* If the comparison value is an invariant register, then try to find
3728 its value from the insns before the start of the loop. */
3730 final_value = comparison_value;
3731 if (GET_CODE (comparison_value) == REG
3732 && loop_invariant_p (loop, comparison_value))
3734 final_value = loop_find_equiv_value (loop, comparison_value);
3736 /* If we don't get an invariant final value, we are better
3737 off with the original register. */
3738 if (! loop_invariant_p (loop, final_value))
3739 final_value = comparison_value;
3742 /* Calculate the approximate final value of the induction variable
3743 (on the last successful iteration). The exact final value
3744 depends on the branch operator, and increment sign. It will be
3745 wrong if the iteration variable is not incremented by one each
3746 time through the loop and (comparison_value + off_by_one -
3747 initial_value) % increment != 0.
3748 ??? Note that the final_value may overflow and thus final_larger
3749 will be bogus. A potentially infinite loop will be classified
3750 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3752 final_value = plus_constant (final_value, off_by_one);
3754 /* Save the calculated values describing this loop's bounds, in case
3755 precondition_loop_p will need them later. These values can not be
3756 recalculated inside precondition_loop_p because strength reduction
3757 optimizations may obscure the loop's structure.
3759 These values are only required by precondition_loop_p and insert_bct
3760 whenever the number of iterations cannot be computed at compile time.
3761 Only the difference between final_value and initial_value is
3762 important. Note that final_value is only approximate. */
3763 loop_info->initial_value = initial_value;
3764 loop_info->comparison_value = comparison_value;
3765 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3766 loop_info->increment = increment;
3767 loop_info->iteration_var = iteration_var;
3768 loop_info->comparison_code = comparison_code;
3771 /* Try to determine the iteration count for loops such
3772 as (for i = init; i < init + const; i++). When running the
3773 loop optimization twice, the first pass often converts simple
3774 loops into this form. */
3776 if (REG_P (initial_value))
3782 reg1 = initial_value;
3783 if (GET_CODE (final_value) == PLUS)
3784 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3786 reg2 = final_value, const2 = const0_rtx;
3788 /* Check for initial_value = reg1, final_value = reg2 + const2,
3789 where reg1 != reg2. */
3790 if (REG_P (reg2) && reg2 != reg1)
3794 /* Find what reg1 is equivalent to. Hopefully it will
3795 either be reg2 or reg2 plus a constant. */
3796 temp = loop_find_equiv_value (loop, reg1);
3798 if (find_common_reg_term (temp, reg2))
3799 initial_value = temp;
3802 /* Find what reg2 is equivalent to. Hopefully it will
3803 either be reg1 or reg1 plus a constant. Let's ignore
3804 the latter case for now since it is not so common. */
3805 temp = loop_find_equiv_value (loop, reg2);
3807 if (temp == loop_info->iteration_var)
3808 temp = initial_value;
3810 final_value = (const2 == const0_rtx)
3811 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3814 else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
3818 /* When running the loop optimizer twice, check_dbra_loop
3819 further obfuscates reversible loops of the form:
3820 for (i = init; i < init + const; i++). We often end up with
3821 final_value = 0, initial_value = temp, temp = temp2 - init,
3822 where temp2 = init + const. If the loop has a vtop we
3823 can replace initial_value with const. */
3825 temp = loop_find_equiv_value (loop, reg1);
3827 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3829 rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
3831 if (GET_CODE (temp2) == PLUS
3832 && XEXP (temp2, 0) == XEXP (temp, 1))
3833 initial_value = XEXP (temp2, 1);
3838 /* If have initial_value = reg + const1 and final_value = reg +
3839 const2, then replace initial_value with const1 and final_value
3840 with const2. This should be safe since we are protected by the
3841 initial comparison before entering the loop if we have a vtop.
3842 For example, a + b < a + c is not equivalent to b < c for all a
3843 when using modulo arithmetic.
3845 ??? Without a vtop we could still perform the optimization if we check
3846 the initial and final values carefully. */
3848 && (reg_term = find_common_reg_term (initial_value, final_value)))
3850 initial_value = subtract_reg_term (initial_value, reg_term);
3851 final_value = subtract_reg_term (final_value, reg_term);
3854 loop_info->initial_equiv_value = initial_value;
3855 loop_info->final_equiv_value = final_value;
3857 /* For EQ comparison loops, we don't have a valid final value.
3858 Check this now so that we won't leave an invalid value if we
3859 return early for any other reason. */
3860 if (comparison_code == EQ)
3861 loop_info->final_equiv_value = loop_info->final_value = 0;
3865 if (loop_dump_stream)
3866 fprintf (loop_dump_stream,
3867 "Loop iterations: Increment value can't be calculated.\n");
3871 if (GET_CODE (increment) != CONST_INT)
3873 /* If we have a REG, check to see if REG holds a constant value. */
3874 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3875 clear if it is worthwhile to try to handle such RTL. */
3876 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3877 increment = loop_find_equiv_value (loop, increment);
3879 if (GET_CODE (increment) != CONST_INT)
3881 if (loop_dump_stream)
3883 fprintf (loop_dump_stream,
3884 "Loop iterations: Increment value not constant ");
3885 print_simple_rtl (loop_dump_stream, increment);
3886 fprintf (loop_dump_stream, ".\n");
3890 loop_info->increment = increment;
3893 if (GET_CODE (initial_value) != CONST_INT)
3895 if (loop_dump_stream)
3897 fprintf (loop_dump_stream,
3898 "Loop iterations: Initial value not constant ");
3899 print_simple_rtl (loop_dump_stream, initial_value);
3900 fprintf (loop_dump_stream, ".\n");
3904 else if (comparison_code == EQ)
3906 if (loop_dump_stream)
3907 fprintf (loop_dump_stream, "Loop iterations: EQ comparison loop.\n");
3910 else if (GET_CODE (final_value) != CONST_INT)
3912 if (loop_dump_stream)
3914 fprintf (loop_dump_stream,
3915 "Loop iterations: Final value not constant ");
3916 print_simple_rtl (loop_dump_stream, final_value);
3917 fprintf (loop_dump_stream, ".\n");
3922 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3925 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3926 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3927 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3928 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3930 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3931 - (INTVAL (final_value) < INTVAL (initial_value));
3933 if (INTVAL (increment) > 0)
3935 else if (INTVAL (increment) == 0)
3940 /* There are 27 different cases: compare_dir = -1, 0, 1;
3941 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3942 There are 4 normal cases, 4 reverse cases (where the iteration variable
3943 will overflow before the loop exits), 4 infinite loop cases, and 15
3944 immediate exit (0 or 1 iteration depending on loop type) cases.
3945 Only try to optimize the normal cases. */
3947 /* (compare_dir/final_larger/increment_dir)
3948 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3949 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3950 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3951 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3953 /* ?? If the meaning of reverse loops (where the iteration variable
3954 will overflow before the loop exits) is undefined, then could
3955 eliminate all of these special checks, and just always assume
3956 the loops are normal/immediate/infinite. Note that this means
3957 the sign of increment_dir does not have to be known. Also,
3958 since it does not really hurt if immediate exit loops or infinite loops
3959 are optimized, then that case could be ignored also, and hence all
3960 loops can be optimized.
3962 According to ANSI Spec, the reverse loop case result is undefined,
3963 because the action on overflow is undefined.
3965 See also the special test for NE loops below. */
3967 if (final_larger == increment_dir && final_larger != 0
3968 && (final_larger == compare_dir || compare_dir == 0))
3973 if (loop_dump_stream)
3974 fprintf (loop_dump_stream, "Loop iterations: Not normal loop.\n");
3978 /* Calculate the number of iterations, final_value is only an approximation,
3979 so correct for that. Note that abs_diff and n_iterations are
3980 unsigned, because they can be as large as 2^n - 1. */
3982 inc = INTVAL (increment);
3985 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
3990 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
3996 /* Given that iteration_var is going to iterate over its own mode,
3997 not HOST_WIDE_INT, disregard higher bits that might have come
3998 into the picture due to sign extension of initial and final
4000 abs_diff &= ((unsigned HOST_WIDE_INT)1
4001 << (GET_MODE_BITSIZE (GET_MODE (iteration_var)) - 1)
4004 /* For NE tests, make sure that the iteration variable won't miss
4005 the final value. If abs_diff mod abs_incr is not zero, then the
4006 iteration variable will overflow before the loop exits, and we
4007 can not calculate the number of iterations. */
4008 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4011 /* Note that the number of iterations could be calculated using
4012 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4013 handle potential overflow of the summation. */
4014 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4015 return loop_info->n_iterations;
4018 /* Replace uses of split bivs with their split pseudo register. This is
4019 for original instructions which remain after loop unrolling without
4023 remap_split_bivs (loop, x)
4027 struct loop_ivs *ivs = LOOP_IVS (loop);
4028 register enum rtx_code code;
4030 register const char *fmt;
4035 code = GET_CODE (x);
4050 /* If non-reduced/final-value givs were split, then this would also
4051 have to remap those givs also. */
4053 if (REGNO (x) < ivs->n_regs
4054 && REG_IV_TYPE (ivs, REGNO (x)) == BASIC_INDUCT)
4055 return REG_IV_CLASS (ivs, REGNO (x))->biv->src_reg;
4062 fmt = GET_RTX_FORMAT (code);
4063 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4066 XEXP (x, i) = remap_split_bivs (loop, XEXP (x, i));
4067 else if (fmt[i] == 'E')
4070 for (j = 0; j < XVECLEN (x, i); j++)
4071 XVECEXP (x, i, j) = remap_split_bivs (loop, XVECEXP (x, i, j));
4077 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4078 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4079 return 0. COPY_START is where we can start looking for the insns
4080 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4083 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4084 must dominate LAST_UID.
4086 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4087 may not dominate LAST_UID.
4089 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4090 must dominate LAST_UID. */
4093 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4100 int passed_jump = 0;
4101 rtx p = NEXT_INSN (copy_start);
4103 while (INSN_UID (p) != first_uid)
4105 if (GET_CODE (p) == JUMP_INSN)
4107 /* Could not find FIRST_UID. */
4113 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4114 if (! INSN_P (p) || ! dead_or_set_regno_p (p, regno))
4117 /* FIRST_UID is always executed. */
4118 if (passed_jump == 0)
4121 while (INSN_UID (p) != last_uid)
4123 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4124 can not be sure that FIRST_UID dominates LAST_UID. */
4125 if (GET_CODE (p) == CODE_LABEL)
4127 /* Could not find LAST_UID, but we reached the end of the loop, so
4129 else if (p == copy_end)
4134 /* FIRST_UID is always executed if LAST_UID is executed. */
4138 /* This routine is called when the number of iterations for the unrolled
4139 loop is one. The goal is to identify a loop that begins with an
4140 unconditional branch to the loop continuation note (or a label just after).
4141 In this case, the unconditional branch that starts the loop needs to be
4142 deleted so that we execute the single iteration. */
4145 ujump_to_loop_cont (loop_start, loop_cont)
4149 rtx x, label, label_ref;
4151 /* See if loop start, or the next insn is an unconditional jump. */
4152 loop_start = next_nonnote_insn (loop_start);
4154 x = pc_set (loop_start);
4158 label_ref = SET_SRC (x);
4162 /* Examine insn after loop continuation note. Return if not a label. */
4163 label = next_nonnote_insn (loop_cont);
4164 if (label == 0 || GET_CODE (label) != CODE_LABEL)
4167 /* Return the loop start if the branch label matches the code label. */
4168 if (CODE_LABEL_NUMBER (label) == CODE_LABEL_NUMBER (XEXP (label_ref, 0)))