1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor { int factor, count; } factors[NUM_FACTORS]
144 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
148 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
154 #include "insn-config.h"
155 #include "integrate.h"
159 #include "function.h"
163 #include "hard-reg-set.h"
164 #include "basic-block.h"
166 /* This controls which loops are unrolled, and by how much we unroll
169 #ifndef MAX_UNROLLED_INSNS
170 #define MAX_UNROLLED_INSNS 100
173 /* Indexed by register number, if non-zero, then it contains a pointer
174 to a struct induction for a DEST_REG giv which has been combined with
175 one of more address givs. This is needed because whenever such a DEST_REG
176 giv is modified, we must modify the value of all split address givs
177 that were combined with this DEST_REG giv. */
179 static struct induction **addr_combined_regs;
181 /* Indexed by register number, if this is a splittable induction variable,
182 then this will hold the current value of the register, which depends on the
185 static rtx *splittable_regs;
187 /* Indexed by register number, if this is a splittable induction variable,
188 this indicates if it was made from a derived giv. */
189 static char *derived_regs;
191 /* Indexed by register number, if this is a splittable induction variable,
192 then this will hold the number of instructions in the loop that modify
193 the induction variable. Used to ensure that only the last insn modifying
194 a split iv will update the original iv of the dest. */
196 static int *splittable_regs_updates;
198 /* Forward declarations. */
200 static void init_reg_map PARAMS ((struct inline_remap *, int));
201 static rtx calculate_giv_inc PARAMS ((rtx, rtx, unsigned int));
202 static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
203 static void final_reg_note_copy PARAMS ((rtx, struct inline_remap *));
204 static void copy_loop_body PARAMS ((struct loop *, rtx, rtx,
205 struct inline_remap *, rtx, int,
206 enum unroll_types, rtx, rtx, rtx, rtx));
207 static int find_splittable_regs PARAMS ((const struct loop *,
208 enum unroll_types, rtx, int));
209 static int find_splittable_givs PARAMS ((const struct loop *,
210 struct iv_class *, enum unroll_types,
212 static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
213 static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
214 static int verify_addresses PARAMS ((struct induction *, rtx, int));
215 static rtx remap_split_bivs PARAMS ((struct loop *, rtx));
216 static rtx find_common_reg_term PARAMS ((rtx, rtx));
217 static rtx subtract_reg_term PARAMS ((rtx, rtx));
218 static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
219 static rtx ujump_to_loop_cont PARAMS ((rtx, rtx));
221 /* Try to unroll one loop and split induction variables in the loop.
223 The loop is described by the arguments LOOP and INSN_COUNT.
224 END_INSERT_BEFORE indicates where insns should be added which need
225 to be executed when the loop falls through. STRENGTH_REDUCTION_P
226 indicates whether information generated in the strength reduction
229 This function is intended to be called from within `strength_reduce'
233 unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
236 rtx end_insert_before;
237 int strength_reduce_p;
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 (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,
447 "Loop unrolling: No factors found.\n");
450 unroll_type = UNROLL_MODULO;
454 /* Default case, calculate number of times to unroll loop based on its
456 if (unroll_type == UNROLL_NAIVE)
458 if (8 * insn_count < MAX_UNROLLED_INSNS)
460 else if (4 * insn_count < MAX_UNROLLED_INSNS)
466 /* Now we know how many times to unroll the loop. */
468 if (loop_dump_stream)
469 fprintf (loop_dump_stream,
470 "Unrolling loop %d times.\n", unroll_number);
473 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
475 /* Loops of these types can start with jump down to the exit condition
476 in rare circumstances.
478 Consider a pair of nested loops where the inner loop is part
479 of the exit code for the outer loop.
481 In this case jump.c will not duplicate the exit test for the outer
482 loop, so it will start with a jump to the exit code.
484 Then consider if the inner loop turns out to iterate once and
485 only once. We will end up deleting the jumps associated with
486 the inner loop. However, the loop notes are not removed from
487 the instruction stream.
489 And finally assume that we can compute the number of iterations
492 In this case unroll may want to unroll the outer loop even though
493 it starts with a jump to the outer loop's exit code.
495 We could try to optimize this case, but it hardly seems worth it.
496 Just return without unrolling the loop in such cases. */
499 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
500 insn = NEXT_INSN (insn);
501 if (GET_CODE (insn) == JUMP_INSN)
505 if (unroll_type == UNROLL_COMPLETELY)
507 /* Completely unrolling the loop: Delete the compare and branch at
508 the end (the last two instructions). This delete must done at the
509 very end of loop unrolling, to avoid problems with calls to
510 back_branch_in_range_p, which is called by find_splittable_regs.
511 All increments of splittable bivs/givs are changed to load constant
514 copy_start = loop_start;
516 /* Set insert_before to the instruction immediately after the JUMP_INSN
517 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
518 the loop will be correctly handled by copy_loop_body. */
519 insert_before = NEXT_INSN (last_loop_insn);
521 /* Set copy_end to the insn before the jump at the end of the loop. */
522 if (GET_CODE (last_loop_insn) == BARRIER)
523 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
524 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
526 copy_end = PREV_INSN (last_loop_insn);
528 /* The instruction immediately before the JUMP_INSN may be a compare
529 instruction which we do not want to copy. */
530 if (sets_cc0_p (PREV_INSN (copy_end)))
531 copy_end = PREV_INSN (copy_end);
536 /* We currently can't unroll a loop if it doesn't end with a
537 JUMP_INSN. There would need to be a mechanism that recognizes
538 this case, and then inserts a jump after each loop body, which
539 jumps to after the last loop body. */
540 if (loop_dump_stream)
541 fprintf (loop_dump_stream,
542 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
546 else if (unroll_type == UNROLL_MODULO)
548 /* Partially unrolling the loop: The compare and branch at the end
549 (the last two instructions) must remain. Don't copy the compare
550 and branch instructions at the end of the loop. Insert the unrolled
551 code immediately before the compare/branch at the end so that the
552 code will fall through to them as before. */
554 copy_start = loop_start;
556 /* Set insert_before to the jump insn at the end of the loop.
557 Set copy_end to before the jump insn at the end of the loop. */
558 if (GET_CODE (last_loop_insn) == BARRIER)
560 insert_before = PREV_INSN (last_loop_insn);
561 copy_end = PREV_INSN (insert_before);
563 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
565 insert_before = last_loop_insn;
567 /* The instruction immediately before the JUMP_INSN may be a compare
568 instruction which we do not want to copy or delete. */
569 if (sets_cc0_p (PREV_INSN (insert_before)))
570 insert_before = PREV_INSN (insert_before);
572 copy_end = PREV_INSN (insert_before);
576 /* We currently can't unroll a loop if it doesn't end with a
577 JUMP_INSN. There would need to be a mechanism that recognizes
578 this case, and then inserts a jump after each loop body, which
579 jumps to after the last loop body. */
580 if (loop_dump_stream)
581 fprintf (loop_dump_stream,
582 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
588 /* Normal case: Must copy the compare and branch instructions at the
591 if (GET_CODE (last_loop_insn) == BARRIER)
593 /* Loop ends with an unconditional jump and a barrier.
594 Handle this like above, don't copy jump and barrier.
595 This is not strictly necessary, but doing so prevents generating
596 unconditional jumps to an immediately following label.
598 This will be corrected below if the target of this jump is
599 not the start_label. */
601 insert_before = PREV_INSN (last_loop_insn);
602 copy_end = PREV_INSN (insert_before);
604 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
606 /* Set insert_before to immediately after the JUMP_INSN, so that
607 NOTEs at the end of the loop will be correctly handled by
609 insert_before = NEXT_INSN (last_loop_insn);
610 copy_end = last_loop_insn;
614 /* We currently can't unroll a loop if it doesn't end with a
615 JUMP_INSN. There would need to be a mechanism that recognizes
616 this case, and then inserts a jump after each loop body, which
617 jumps to after the last loop body. */
618 if (loop_dump_stream)
619 fprintf (loop_dump_stream,
620 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
624 /* If copying exit test branches because they can not be eliminated,
625 then must convert the fall through case of the branch to a jump past
626 the end of the loop. Create a label to emit after the loop and save
627 it for later use. Do not use the label after the loop, if any, since
628 it might be used by insns outside the loop, or there might be insns
629 added before it later by final_[bg]iv_value which must be after
630 the real exit label. */
631 exit_label = gen_label_rtx ();
634 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
635 insn = NEXT_INSN (insn);
637 if (GET_CODE (insn) == JUMP_INSN)
639 /* The loop starts with a jump down to the exit condition test.
640 Start copying the loop after the barrier following this
642 copy_start = NEXT_INSN (insn);
644 /* Splitting induction variables doesn't work when the loop is
645 entered via a jump to the bottom, because then we end up doing
646 a comparison against a new register for a split variable, but
647 we did not execute the set insn for the new register because
648 it was skipped over. */
649 splitting_not_safe = 1;
650 if (loop_dump_stream)
651 fprintf (loop_dump_stream,
652 "Splitting not safe, because loop not entered at top.\n");
655 copy_start = loop_start;
658 /* This should always be the first label in the loop. */
659 start_label = NEXT_INSN (copy_start);
660 /* There may be a line number note and/or a loop continue note here. */
661 while (GET_CODE (start_label) == NOTE)
662 start_label = NEXT_INSN (start_label);
663 if (GET_CODE (start_label) != CODE_LABEL)
665 /* This can happen as a result of jump threading. If the first insns in
666 the loop test the same condition as the loop's backward jump, or the
667 opposite condition, then the backward jump will be modified to point
668 to elsewhere, and the loop's start label is deleted.
670 This case currently can not be handled by the loop unrolling code. */
672 if (loop_dump_stream)
673 fprintf (loop_dump_stream,
674 "Unrolling failure: unknown insns between BEG note and loop label.\n");
677 if (LABEL_NAME (start_label))
679 /* The jump optimization pass must have combined the original start label
680 with a named label for a goto. We can't unroll this case because
681 jumps which go to the named label must be handled differently than
682 jumps to the loop start, and it is impossible to differentiate them
684 if (loop_dump_stream)
685 fprintf (loop_dump_stream,
686 "Unrolling failure: loop start label is gone\n");
690 if (unroll_type == UNROLL_NAIVE
691 && GET_CODE (last_loop_insn) == BARRIER
692 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
693 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
695 /* In this case, we must copy the jump and barrier, because they will
696 not be converted to jumps to an immediately following label. */
698 insert_before = NEXT_INSN (last_loop_insn);
699 copy_end = last_loop_insn;
702 if (unroll_type == UNROLL_NAIVE
703 && GET_CODE (last_loop_insn) == JUMP_INSN
704 && start_label != JUMP_LABEL (last_loop_insn))
706 /* ??? The loop ends with a conditional branch that does not branch back
707 to the loop start label. In this case, we must emit an unconditional
708 branch to the loop exit after emitting the final branch.
709 copy_loop_body does not have support for this currently, so we
710 give up. It doesn't seem worthwhile to unroll anyways since
711 unrolling would increase the number of branch instructions
713 if (loop_dump_stream)
714 fprintf (loop_dump_stream,
715 "Unrolling failure: final conditional branch not to loop start\n");
719 /* Allocate a translation table for the labels and insn numbers.
720 They will be filled in as we copy the insns in the loop. */
722 max_labelno = max_label_num ();
723 max_insnno = get_max_uid ();
725 /* Various paths through the unroll code may reach the "egress" label
726 without initializing fields within the map structure.
728 To be safe, we use xcalloc to zero the memory. */
729 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
731 /* Allocate the label map. */
735 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
737 local_label = (char *) xcalloc (max_labelno, sizeof (char));
740 /* Search the loop and mark all local labels, i.e. the ones which have to
741 be distinct labels when copied. For all labels which might be
742 non-local, set their label_map entries to point to themselves.
743 If they happen to be local their label_map entries will be overwritten
744 before the loop body is copied. The label_map entries for local labels
745 will be set to a different value each time the loop body is copied. */
747 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
751 if (GET_CODE (insn) == CODE_LABEL)
752 local_label[CODE_LABEL_NUMBER (insn)] = 1;
753 else if (GET_CODE (insn) == JUMP_INSN)
755 if (JUMP_LABEL (insn))
756 set_label_in_map (map,
757 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
759 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
760 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
762 rtx pat = PATTERN (insn);
763 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
764 int len = XVECLEN (pat, diff_vec_p);
767 for (i = 0; i < len; i++)
769 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
770 set_label_in_map (map,
771 CODE_LABEL_NUMBER (label),
776 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
777 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
781 /* Allocate space for the insn map. */
783 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
785 /* Set this to zero, to indicate that we are doing loop unrolling,
786 not function inlining. */
787 map->inline_target = 0;
789 /* The register and constant maps depend on the number of registers
790 present, so the final maps can't be created until after
791 find_splittable_regs is called. However, they are needed for
792 preconditioning, so we create temporary maps when preconditioning
795 /* The preconditioning code may allocate two new pseudo registers. */
796 maxregnum = max_reg_num ();
798 /* local_regno is only valid for regnos < max_local_regnum. */
799 max_local_regnum = maxregnum;
801 /* Allocate and zero out the splittable_regs and addr_combined_regs
802 arrays. These must be zeroed here because they will be used if
803 loop preconditioning is performed, and must be zero for that case.
805 It is safe to do this here, since the extra registers created by the
806 preconditioning code and find_splittable_regs will never be used
807 to access the splittable_regs[] and addr_combined_regs[] arrays. */
809 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
810 derived_regs = (char *) xcalloc (maxregnum, sizeof (char));
811 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
813 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
814 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
816 /* Mark all local registers, i.e. the ones which are referenced only
818 if (INSN_UID (copy_end) < max_uid_for_loop)
820 int copy_start_luid = INSN_LUID (copy_start);
821 int copy_end_luid = INSN_LUID (copy_end);
823 /* If a register is used in the jump insn, we must not duplicate it
824 since it will also be used outside the loop. */
825 if (GET_CODE (copy_end) == JUMP_INSN)
828 /* If we have a target that uses cc0, then we also must not duplicate
829 the insn that sets cc0 before the jump insn, if one is present. */
831 if (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
835 /* If copy_start points to the NOTE that starts the loop, then we must
836 use the next luid, because invariant pseudo-regs moved out of the loop
837 have their lifetimes modified to start here, but they are not safe
839 if (copy_start == loop_start)
842 /* If a pseudo's lifetime is entirely contained within this loop, then we
843 can use a different pseudo in each unrolled copy of the loop. This
844 results in better code. */
845 /* We must limit the generic test to max_reg_before_loop, because only
846 these pseudo registers have valid regno_first_uid info. */
847 for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r)
848 if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) <= max_uid_for_loop
849 && uid_luid[REGNO_FIRST_UID (r)] >= copy_start_luid
850 && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) <= max_uid_for_loop
851 && uid_luid[REGNO_LAST_UID (r)] <= copy_end_luid)
853 /* However, we must also check for loop-carried dependencies.
854 If the value the pseudo has at the end of iteration X is
855 used by iteration X+1, then we can not use a different pseudo
856 for each unrolled copy of the loop. */
857 /* A pseudo is safe if regno_first_uid is a set, and this
858 set dominates all instructions from regno_first_uid to
860 /* ??? This check is simplistic. We would get better code if
861 this check was more sophisticated. */
862 if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r),
863 copy_start, copy_end))
866 if (loop_dump_stream)
869 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
871 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
875 /* Givs that have been created from multiple biv increments always have
877 for (r = ivs->first_increment_giv; r <= ivs->last_increment_giv; r++)
880 if (loop_dump_stream)
881 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
885 /* If this loop requires exit tests when unrolled, check to see if we
886 can precondition the loop so as to make the exit tests unnecessary.
887 Just like variable splitting, this is not safe if the loop is entered
888 via a jump to the bottom. Also, can not do this if no strength
889 reduce info, because precondition_loop_p uses this info. */
891 /* Must copy the loop body for preconditioning before the following
892 find_splittable_regs call since that will emit insns which need to
893 be after the preconditioned loop copies, but immediately before the
894 unrolled loop copies. */
896 /* Also, it is not safe to split induction variables for the preconditioned
897 copies of the loop body. If we split induction variables, then the code
898 assumes that each induction variable can be represented as a function
899 of its initial value and the loop iteration number. This is not true
900 in this case, because the last preconditioned copy of the loop body
901 could be any iteration from the first up to the `unroll_number-1'th,
902 depending on the initial value of the iteration variable. Therefore
903 we can not split induction variables here, because we can not calculate
904 their value. Hence, this code must occur before find_splittable_regs
907 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
909 rtx initial_value, final_value, increment;
910 enum machine_mode mode;
912 if (precondition_loop_p (loop,
913 &initial_value, &final_value, &increment,
918 int abs_inc, neg_inc;
920 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
922 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
923 "unroll_loop_precondition");
924 global_const_equiv_varray = map->const_equiv_varray;
926 init_reg_map (map, maxregnum);
928 /* Limit loop unrolling to 4, since this will make 7 copies of
930 if (unroll_number > 4)
933 /* Save the absolute value of the increment, and also whether or
934 not it is negative. */
936 abs_inc = INTVAL (increment);
945 /* Calculate the difference between the final and initial values.
946 Final value may be a (plus (reg x) (const_int 1)) rtx.
947 Let the following cse pass simplify this if initial value is
950 We must copy the final and initial values here to avoid
951 improperly shared rtl. */
953 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
954 copy_rtx (initial_value), NULL_RTX, 0,
957 /* Now calculate (diff % (unroll * abs (increment))) by using an
959 diff = expand_binop (GET_MODE (diff), and_optab, diff,
960 GEN_INT (unroll_number * abs_inc - 1),
961 NULL_RTX, 0, OPTAB_LIB_WIDEN);
963 /* Now emit a sequence of branches to jump to the proper precond
966 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
967 for (i = 0; i < unroll_number; i++)
968 labels[i] = gen_label_rtx ();
970 /* Check for the case where the initial value is greater than or
971 equal to the final value. In that case, we want to execute
972 exactly one loop iteration. The code below will fail for this
973 case. This check does not apply if the loop has a NE
974 comparison at the end. */
976 if (loop_info->comparison_code != NE)
978 emit_cmp_and_jump_insns (initial_value, final_value,
980 NULL_RTX, mode, 0, 0, labels[1]);
981 JUMP_LABEL (get_last_insn ()) = labels[1];
982 LABEL_NUSES (labels[1])++;
985 /* Assuming the unroll_number is 4, and the increment is 2, then
986 for a negative increment: for a positive increment:
987 diff = 0,1 precond 0 diff = 0,7 precond 0
988 diff = 2,3 precond 3 diff = 1,2 precond 1
989 diff = 4,5 precond 2 diff = 3,4 precond 2
990 diff = 6,7 precond 1 diff = 5,6 precond 3 */
992 /* We only need to emit (unroll_number - 1) branches here, the
993 last case just falls through to the following code. */
995 /* ??? This would give better code if we emitted a tree of branches
996 instead of the current linear list of branches. */
998 for (i = 0; i < unroll_number - 1; i++)
1001 enum rtx_code cmp_code;
1003 /* For negative increments, must invert the constant compared
1004 against, except when comparing against zero. */
1012 cmp_const = unroll_number - i;
1021 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
1022 cmp_code, NULL_RTX, mode, 0, 0,
1024 JUMP_LABEL (get_last_insn ()) = labels[i];
1025 LABEL_NUSES (labels[i])++;
1028 /* If the increment is greater than one, then we need another branch,
1029 to handle other cases equivalent to 0. */
1031 /* ??? This should be merged into the code above somehow to help
1032 simplify the code here, and reduce the number of branches emitted.
1033 For the negative increment case, the branch here could easily
1034 be merged with the `0' case branch above. For the positive
1035 increment case, it is not clear how this can be simplified. */
1040 enum rtx_code cmp_code;
1044 cmp_const = abs_inc - 1;
1049 cmp_const = abs_inc * (unroll_number - 1) + 1;
1053 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1054 NULL_RTX, mode, 0, 0, labels[0]);
1055 JUMP_LABEL (get_last_insn ()) = labels[0];
1056 LABEL_NUSES (labels[0])++;
1059 sequence = gen_sequence ();
1061 emit_insn_before (sequence, loop_start);
1063 /* Only the last copy of the loop body here needs the exit
1064 test, so set copy_end to exclude the compare/branch here,
1065 and then reset it inside the loop when get to the last
1068 if (GET_CODE (last_loop_insn) == BARRIER)
1069 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1070 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1072 copy_end = PREV_INSN (last_loop_insn);
1074 /* The immediately preceding insn may be a compare which we do not
1076 if (sets_cc0_p (PREV_INSN (copy_end)))
1077 copy_end = PREV_INSN (copy_end);
1083 for (i = 1; i < unroll_number; i++)
1085 emit_label_after (labels[unroll_number - i],
1086 PREV_INSN (loop_start));
1088 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1089 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1090 (VARRAY_SIZE (map->const_equiv_varray)
1091 * sizeof (struct const_equiv_data)));
1094 for (j = 0; j < max_labelno; j++)
1096 set_label_in_map (map, j, gen_label_rtx ());
1098 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1102 = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1103 record_base_value (REGNO (map->reg_map[r]),
1104 regno_reg_rtx[r], 0);
1106 /* The last copy needs the compare/branch insns at the end,
1107 so reset copy_end here if the loop ends with a conditional
1110 if (i == unroll_number - 1)
1112 if (GET_CODE (last_loop_insn) == BARRIER)
1113 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1115 copy_end = last_loop_insn;
1118 /* None of the copies are the `last_iteration', so just
1119 pass zero for that parameter. */
1120 copy_loop_body (loop, copy_start, copy_end, map, exit_label, 0,
1121 unroll_type, start_label, loop_end,
1122 loop_start, copy_end);
1124 emit_label_after (labels[0], PREV_INSN (loop_start));
1126 if (GET_CODE (last_loop_insn) == BARRIER)
1128 insert_before = PREV_INSN (last_loop_insn);
1129 copy_end = PREV_INSN (insert_before);
1133 insert_before = last_loop_insn;
1135 /* The instruction immediately before the JUMP_INSN may be a compare
1136 instruction which we do not want to copy or delete. */
1137 if (sets_cc0_p (PREV_INSN (insert_before)))
1138 insert_before = PREV_INSN (insert_before);
1140 copy_end = PREV_INSN (insert_before);
1143 /* Set unroll type to MODULO now. */
1144 unroll_type = UNROLL_MODULO;
1145 loop_preconditioned = 1;
1152 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1153 the loop unless all loops are being unrolled. */
1154 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1156 if (loop_dump_stream)
1157 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1161 /* At this point, we are guaranteed to unroll the loop. */
1163 /* Keep track of the unroll factor for the loop. */
1164 loop_info->unroll_number = unroll_number;
1166 /* For each biv and giv, determine whether it can be safely split into
1167 a different variable for each unrolled copy of the loop body.
1168 We precalculate and save this info here, since computing it is
1171 Do this before deleting any instructions from the loop, so that
1172 back_branch_in_range_p will work correctly. */
1174 if (splitting_not_safe)
1177 temp = find_splittable_regs (loop, unroll_type,
1178 end_insert_before, unroll_number);
1180 /* find_splittable_regs may have created some new registers, so must
1181 reallocate the reg_map with the new larger size, and must realloc
1182 the constant maps also. */
1184 maxregnum = max_reg_num ();
1185 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1187 init_reg_map (map, maxregnum);
1189 if (map->const_equiv_varray == 0)
1190 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1191 maxregnum + temp * unroll_number * 2,
1193 global_const_equiv_varray = map->const_equiv_varray;
1195 /* Search the list of bivs and givs to find ones which need to be remapped
1196 when split, and set their reg_map entry appropriately. */
1198 for (bl = ivs->loop_iv_list; bl; bl = bl->next)
1200 if (REGNO (bl->biv->src_reg) != bl->regno)
1201 map->reg_map[bl->regno] = bl->biv->src_reg;
1203 /* Currently, non-reduced/final-value givs are never split. */
1204 for (v = bl->giv; v; v = v->next_iv)
1205 if (REGNO (v->src_reg) != bl->regno)
1206 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1210 /* Use our current register alignment and pointer flags. */
1211 map->regno_pointer_flag = cfun->emit->regno_pointer_flag;
1212 map->regno_pointer_align = cfun->emit->regno_pointer_align;
1214 /* If the loop is being partially unrolled, and the iteration variables
1215 are being split, and are being renamed for the split, then must fix up
1216 the compare/jump instruction at the end of the loop to refer to the new
1217 registers. This compare isn't copied, so the registers used in it
1218 will never be replaced if it isn't done here. */
1220 if (unroll_type == UNROLL_MODULO)
1222 insn = NEXT_INSN (copy_end);
1223 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1224 PATTERN (insn) = remap_split_bivs (loop, PATTERN (insn));
1227 /* For unroll_number times, make a copy of each instruction
1228 between copy_start and copy_end, and insert these new instructions
1229 before the end of the loop. */
1231 for (i = 0; i < unroll_number; i++)
1233 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1234 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1235 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1238 for (j = 0; j < max_labelno; j++)
1240 set_label_in_map (map, j, gen_label_rtx ());
1242 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1245 map->reg_map[r] = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1246 record_base_value (REGNO (map->reg_map[r]),
1247 regno_reg_rtx[r], 0);
1250 /* If loop starts with a branch to the test, then fix it so that
1251 it points to the test of the first unrolled copy of the loop. */
1252 if (i == 0 && loop_start != copy_start)
1254 insn = PREV_INSN (copy_start);
1255 pattern = PATTERN (insn);
1257 tem = get_label_from_map (map,
1259 (XEXP (SET_SRC (pattern), 0)));
1260 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1262 /* Set the jump label so that it can be used by later loop unrolling
1264 JUMP_LABEL (insn) = tem;
1265 LABEL_NUSES (tem)++;
1268 copy_loop_body (loop, copy_start, copy_end, map, exit_label,
1269 i == unroll_number - 1, unroll_type, start_label,
1270 loop_end, insert_before, insert_before);
1273 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1274 insn to be deleted. This prevents any runaway delete_insn call from
1275 more insns that it should, as it always stops at a CODE_LABEL. */
1277 /* Delete the compare and branch at the end of the loop if completely
1278 unrolling the loop. Deleting the backward branch at the end also
1279 deletes the code label at the start of the loop. This is done at
1280 the very end to avoid problems with back_branch_in_range_p. */
1282 if (unroll_type == UNROLL_COMPLETELY)
1283 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1285 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1287 /* Delete all of the original loop instructions. Don't delete the
1288 LOOP_BEG note, or the first code label in the loop. */
1290 insn = NEXT_INSN (copy_start);
1291 while (insn != safety_label)
1293 /* ??? Don't delete named code labels. They will be deleted when the
1294 jump that references them is deleted. Otherwise, we end up deleting
1295 them twice, which causes them to completely disappear instead of turn
1296 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1297 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1298 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1299 associated LABEL_DECL to point to one of the new label instances. */
1300 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1301 if (insn != start_label
1302 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1303 && ! (GET_CODE (insn) == NOTE
1304 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1305 insn = delete_insn (insn);
1307 insn = NEXT_INSN (insn);
1310 /* Can now delete the 'safety' label emitted to protect us from runaway
1311 delete_insn calls. */
1312 if (INSN_DELETED_P (safety_label))
1314 delete_insn (safety_label);
1316 /* If exit_label exists, emit it after the loop. Doing the emit here
1317 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1318 This is needed so that mostly_true_jump in reorg.c will treat jumps
1319 to this loop end label correctly, i.e. predict that they are usually
1322 emit_label_after (exit_label, loop_end);
1325 if (unroll_type == UNROLL_COMPLETELY)
1327 /* Remove the loop notes since this is no longer a loop. */
1329 delete_insn (loop->vtop);
1331 delete_insn (loop->cont);
1333 delete_insn (loop_start);
1335 delete_insn (loop_end);
1338 if (map->const_equiv_varray)
1339 VARRAY_FREE (map->const_equiv_varray);
1342 free (map->label_map);
1345 free (map->insn_map);
1346 free (splittable_regs);
1347 free (derived_regs);
1348 free (splittable_regs_updates);
1349 free (addr_combined_regs);
1352 free (map->reg_map);
1356 /* Return true if the loop can be safely, and profitably, preconditioned
1357 so that the unrolled copies of the loop body don't need exit tests.
1359 This only works if final_value, initial_value and increment can be
1360 determined, and if increment is a constant power of 2.
1361 If increment is not a power of 2, then the preconditioning modulo
1362 operation would require a real modulo instead of a boolean AND, and this
1363 is not considered `profitable'. */
1365 /* ??? If the loop is known to be executed very many times, or the machine
1366 has a very cheap divide instruction, then preconditioning is a win even
1367 when the increment is not a power of 2. Use RTX_COST to compute
1368 whether divide is cheap.
1369 ??? A divide by constant doesn't actually need a divide, look at
1370 expand_divmod. The reduced cost of this optimized modulo is not
1371 reflected in RTX_COST. */
1374 precondition_loop_p (loop, initial_value, final_value, increment, mode)
1375 const struct loop *loop;
1376 rtx *initial_value, *final_value, *increment;
1377 enum machine_mode *mode;
1379 rtx loop_start = loop->start;
1380 struct loop_info *loop_info = LOOP_INFO (loop);
1382 if (loop_info->n_iterations > 0)
1384 *initial_value = const0_rtx;
1385 *increment = const1_rtx;
1386 *final_value = GEN_INT (loop_info->n_iterations);
1389 if (loop_dump_stream)
1391 fputs ("Preconditioning: Success, number of iterations known, ",
1393 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1394 loop_info->n_iterations);
1395 fputs (".\n", loop_dump_stream);
1400 if (loop_info->initial_value == 0)
1402 if (loop_dump_stream)
1403 fprintf (loop_dump_stream,
1404 "Preconditioning: Could not find initial value.\n");
1407 else if (loop_info->increment == 0)
1409 if (loop_dump_stream)
1410 fprintf (loop_dump_stream,
1411 "Preconditioning: Could not find increment value.\n");
1414 else if (GET_CODE (loop_info->increment) != CONST_INT)
1416 if (loop_dump_stream)
1417 fprintf (loop_dump_stream,
1418 "Preconditioning: Increment not a constant.\n");
1421 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1422 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1424 if (loop_dump_stream)
1425 fprintf (loop_dump_stream,
1426 "Preconditioning: Increment not a constant power of 2.\n");
1430 /* Unsigned_compare and compare_dir can be ignored here, since they do
1431 not matter for preconditioning. */
1433 if (loop_info->final_value == 0)
1435 if (loop_dump_stream)
1436 fprintf (loop_dump_stream,
1437 "Preconditioning: EQ comparison loop.\n");
1441 /* Must ensure that final_value is invariant, so call
1442 loop_invariant_p to check. Before doing so, must check regno
1443 against max_reg_before_loop to make sure that the register is in
1444 the range covered by loop_invariant_p. If it isn't, then it is
1445 most likely a biv/giv which by definition are not invariant. */
1446 if ((GET_CODE (loop_info->final_value) == REG
1447 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1448 || (GET_CODE (loop_info->final_value) == PLUS
1449 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1450 || ! loop_invariant_p (loop, loop_info->final_value))
1452 if (loop_dump_stream)
1453 fprintf (loop_dump_stream,
1454 "Preconditioning: Final value not invariant.\n");
1458 /* Fail for floating point values, since the caller of this function
1459 does not have code to deal with them. */
1460 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1461 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1463 if (loop_dump_stream)
1464 fprintf (loop_dump_stream,
1465 "Preconditioning: Floating point final or initial value.\n");
1469 /* Fail if loop_info->iteration_var is not live before loop_start,
1470 since we need to test its value in the preconditioning code. */
1472 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1473 > INSN_LUID (loop_start))
1475 if (loop_dump_stream)
1476 fprintf (loop_dump_stream,
1477 "Preconditioning: Iteration var not live before loop start.\n");
1481 /* Note that loop_iterations biases the initial value for GIV iterators
1482 such as "while (i-- > 0)" so that we can calculate the number of
1483 iterations just like for BIV iterators.
1485 Also note that the absolute values of initial_value and
1486 final_value are unimportant as only their difference is used for
1487 calculating the number of loop iterations. */
1488 *initial_value = loop_info->initial_value;
1489 *increment = loop_info->increment;
1490 *final_value = loop_info->final_value;
1492 /* Decide what mode to do these calculations in. Choose the larger
1493 of final_value's mode and initial_value's mode, or a full-word if
1494 both are constants. */
1495 *mode = GET_MODE (*final_value);
1496 if (*mode == VOIDmode)
1498 *mode = GET_MODE (*initial_value);
1499 if (*mode == VOIDmode)
1502 else if (*mode != GET_MODE (*initial_value)
1503 && (GET_MODE_SIZE (*mode)
1504 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1505 *mode = GET_MODE (*initial_value);
1508 if (loop_dump_stream)
1509 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1514 /* All pseudo-registers must be mapped to themselves. Two hard registers
1515 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1516 REGNUM, to avoid function-inlining specific conversions of these
1517 registers. All other hard regs can not be mapped because they may be
1522 init_reg_map (map, maxregnum)
1523 struct inline_remap *map;
1528 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1529 map->reg_map[i] = regno_reg_rtx[i];
1530 /* Just clear the rest of the entries. */
1531 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1532 map->reg_map[i] = 0;
1534 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1535 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1536 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1537 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1540 /* Strength-reduction will often emit code for optimized biv/givs which
1541 calculates their value in a temporary register, and then copies the result
1542 to the iv. This procedure reconstructs the pattern computing the iv;
1543 verifying that all operands are of the proper form.
1545 PATTERN must be the result of single_set.
1546 The return value is the amount that the giv is incremented by. */
1549 calculate_giv_inc (pattern, src_insn, regno)
1550 rtx pattern, src_insn;
1554 rtx increment_total = 0;
1558 /* Verify that we have an increment insn here. First check for a plus
1559 as the set source. */
1560 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1562 /* SR sometimes computes the new giv value in a temp, then copies it
1564 src_insn = PREV_INSN (src_insn);
1565 pattern = PATTERN (src_insn);
1566 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1569 /* The last insn emitted is not needed, so delete it to avoid confusing
1570 the second cse pass. This insn sets the giv unnecessarily. */
1571 delete_insn (get_last_insn ());
1574 /* Verify that we have a constant as the second operand of the plus. */
1575 increment = XEXP (SET_SRC (pattern), 1);
1576 if (GET_CODE (increment) != CONST_INT)
1578 /* SR sometimes puts the constant in a register, especially if it is
1579 too big to be an add immed operand. */
1580 src_insn = PREV_INSN (src_insn);
1581 increment = SET_SRC (PATTERN (src_insn));
1583 /* SR may have used LO_SUM to compute the constant if it is too large
1584 for a load immed operand. In this case, the constant is in operand
1585 one of the LO_SUM rtx. */
1586 if (GET_CODE (increment) == LO_SUM)
1587 increment = XEXP (increment, 1);
1589 /* Some ports store large constants in memory and add a REG_EQUAL
1590 note to the store insn. */
1591 else if (GET_CODE (increment) == MEM)
1593 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1595 increment = XEXP (note, 0);
1598 else if (GET_CODE (increment) == IOR
1599 || GET_CODE (increment) == ASHIFT
1600 || GET_CODE (increment) == PLUS)
1602 /* The rs6000 port loads some constants with IOR.
1603 The alpha port loads some constants with ASHIFT and PLUS. */
1604 rtx second_part = XEXP (increment, 1);
1605 enum rtx_code code = GET_CODE (increment);
1607 src_insn = PREV_INSN (src_insn);
1608 increment = SET_SRC (PATTERN (src_insn));
1609 /* Don't need the last insn anymore. */
1610 delete_insn (get_last_insn ());
1612 if (GET_CODE (second_part) != CONST_INT
1613 || GET_CODE (increment) != CONST_INT)
1617 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1618 else if (code == PLUS)
1619 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1621 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1624 if (GET_CODE (increment) != CONST_INT)
1627 /* The insn loading the constant into a register is no longer needed,
1629 delete_insn (get_last_insn ());
1632 if (increment_total)
1633 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1635 increment_total = increment;
1637 /* Check that the source register is the same as the register we expected
1638 to see as the source. If not, something is seriously wrong. */
1639 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1640 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1642 /* Some machines (e.g. the romp), may emit two add instructions for
1643 certain constants, so lets try looking for another add immediately
1644 before this one if we have only seen one add insn so far. */
1650 src_insn = PREV_INSN (src_insn);
1651 pattern = PATTERN (src_insn);
1653 delete_insn (get_last_insn ());
1661 return increment_total;
1664 /* Copy REG_NOTES, except for insn references, because not all insn_map
1665 entries are valid yet. We do need to copy registers now though, because
1666 the reg_map entries can change during copying. */
1669 initial_reg_note_copy (notes, map)
1671 struct inline_remap *map;
1678 copy = rtx_alloc (GET_CODE (notes));
1679 PUT_MODE (copy, GET_MODE (notes));
1681 if (GET_CODE (notes) == EXPR_LIST)
1682 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1683 else if (GET_CODE (notes) == INSN_LIST)
1684 /* Don't substitute for these yet. */
1685 XEXP (copy, 0) = XEXP (notes, 0);
1689 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1694 /* Fixup insn references in copied REG_NOTES. */
1697 final_reg_note_copy (notes, map)
1699 struct inline_remap *map;
1703 for (note = notes; note; note = XEXP (note, 1))
1704 if (GET_CODE (note) == INSN_LIST)
1705 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1708 /* Copy each instruction in the loop, substituting from map as appropriate.
1709 This is very similar to a loop in expand_inline_function. */
1712 copy_loop_body (loop, copy_start, copy_end, map, exit_label, last_iteration,
1713 unroll_type, start_label, loop_end, insert_before,
1716 rtx copy_start, copy_end;
1717 struct inline_remap *map;
1720 enum unroll_types unroll_type;
1721 rtx start_label, loop_end, insert_before, copy_notes_from;
1723 struct loop_ivs *ivs = LOOP_IVS (loop);
1725 rtx set, tem, copy = NULL_RTX;
1726 int dest_reg_was_split, i;
1730 rtx final_label = 0;
1731 rtx giv_inc, giv_dest_reg, giv_src_reg;
1733 /* If this isn't the last iteration, then map any references to the
1734 start_label to final_label. Final label will then be emitted immediately
1735 after the end of this loop body if it was ever used.
1737 If this is the last iteration, then map references to the start_label
1739 if (! last_iteration)
1741 final_label = gen_label_rtx ();
1742 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1746 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1750 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1751 Else gen_sequence could return a raw pattern for a jump which we pass
1752 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1753 a variety of losing behaviors later. */
1754 emit_note (0, NOTE_INSN_DELETED);
1759 insn = NEXT_INSN (insn);
1761 map->orig_asm_operands_vector = 0;
1763 switch (GET_CODE (insn))
1766 pattern = PATTERN (insn);
1770 /* Check to see if this is a giv that has been combined with
1771 some split address givs. (Combined in the sense that
1772 `combine_givs' in loop.c has put two givs in the same register.)
1773 In this case, we must search all givs based on the same biv to
1774 find the address givs. Then split the address givs.
1775 Do this before splitting the giv, since that may map the
1776 SET_DEST to a new register. */
1778 if ((set = single_set (insn))
1779 && GET_CODE (SET_DEST (set)) == REG
1780 && addr_combined_regs[REGNO (SET_DEST (set))])
1782 struct iv_class *bl;
1783 struct induction *v, *tv;
1784 unsigned int regno = REGNO (SET_DEST (set));
1786 v = addr_combined_regs[REGNO (SET_DEST (set))];
1787 bl = ivs->reg_biv_class[REGNO (v->src_reg)];
1789 /* Although the giv_inc amount is not needed here, we must call
1790 calculate_giv_inc here since it might try to delete the
1791 last insn emitted. If we wait until later to call it,
1792 we might accidentally delete insns generated immediately
1793 below by emit_unrolled_add. */
1795 if (! derived_regs[regno])
1796 giv_inc = calculate_giv_inc (set, insn, regno);
1798 /* Now find all address giv's that were combined with this
1800 for (tv = bl->giv; tv; tv = tv->next_iv)
1801 if (tv->giv_type == DEST_ADDR && tv->same == v)
1805 /* If this DEST_ADDR giv was not split, then ignore it. */
1806 if (*tv->location != tv->dest_reg)
1809 /* Scale this_giv_inc if the multiplicative factors of
1810 the two givs are different. */
1811 this_giv_inc = INTVAL (giv_inc);
1812 if (tv->mult_val != v->mult_val)
1813 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1814 * INTVAL (tv->mult_val));
1816 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1817 *tv->location = tv->dest_reg;
1819 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1821 /* Must emit an insn to increment the split address
1822 giv. Add in the const_adjust field in case there
1823 was a constant eliminated from the address. */
1824 rtx value, dest_reg;
1826 /* tv->dest_reg will be either a bare register,
1827 or else a register plus a constant. */
1828 if (GET_CODE (tv->dest_reg) == REG)
1829 dest_reg = tv->dest_reg;
1831 dest_reg = XEXP (tv->dest_reg, 0);
1833 /* Check for shared address givs, and avoid
1834 incrementing the shared pseudo reg more than
1836 if (! tv->same_insn && ! tv->shared)
1838 /* tv->dest_reg may actually be a (PLUS (REG)
1839 (CONST)) here, so we must call plus_constant
1840 to add the const_adjust amount before calling
1841 emit_unrolled_add below. */
1842 value = plus_constant (tv->dest_reg,
1845 if (GET_CODE (value) == PLUS)
1847 /* The constant could be too large for an add
1848 immediate, so can't directly emit an insn
1850 emit_unrolled_add (dest_reg, XEXP (value, 0),
1855 /* Reset the giv to be just the register again, in case
1856 it is used after the set we have just emitted.
1857 We must subtract the const_adjust factor added in
1859 tv->dest_reg = plus_constant (dest_reg,
1860 - tv->const_adjust);
1861 *tv->location = tv->dest_reg;
1866 /* If this is a setting of a splittable variable, then determine
1867 how to split the variable, create a new set based on this split,
1868 and set up the reg_map so that later uses of the variable will
1869 use the new split variable. */
1871 dest_reg_was_split = 0;
1873 if ((set = single_set (insn))
1874 && GET_CODE (SET_DEST (set)) == REG
1875 && splittable_regs[REGNO (SET_DEST (set))])
1877 unsigned int regno = REGNO (SET_DEST (set));
1878 unsigned int src_regno;
1880 dest_reg_was_split = 1;
1882 giv_dest_reg = SET_DEST (set);
1883 if (derived_regs[regno])
1885 /* ??? This relies on SET_SRC (SET) to be of
1886 the form (plus (reg) (const_int)), and thus
1887 forces recombine_givs to restrict the kind
1888 of giv derivations it does before unrolling. */
1889 giv_src_reg = XEXP (SET_SRC (set), 0);
1890 giv_inc = XEXP (SET_SRC (set), 1);
1894 giv_src_reg = giv_dest_reg;
1895 /* Compute the increment value for the giv, if it wasn't
1896 already computed above. */
1898 giv_inc = calculate_giv_inc (set, insn, regno);
1900 src_regno = REGNO (giv_src_reg);
1902 if (unroll_type == UNROLL_COMPLETELY)
1904 /* Completely unrolling the loop. Set the induction
1905 variable to a known constant value. */
1907 /* The value in splittable_regs may be an invariant
1908 value, so we must use plus_constant here. */
1909 splittable_regs[regno]
1910 = plus_constant (splittable_regs[src_regno],
1913 if (GET_CODE (splittable_regs[regno]) == PLUS)
1915 giv_src_reg = XEXP (splittable_regs[regno], 0);
1916 giv_inc = XEXP (splittable_regs[regno], 1);
1920 /* The splittable_regs value must be a REG or a
1921 CONST_INT, so put the entire value in the giv_src_reg
1923 giv_src_reg = splittable_regs[regno];
1924 giv_inc = const0_rtx;
1929 /* Partially unrolling loop. Create a new pseudo
1930 register for the iteration variable, and set it to
1931 be a constant plus the original register. Except
1932 on the last iteration, when the result has to
1933 go back into the original iteration var register. */
1935 /* Handle bivs which must be mapped to a new register
1936 when split. This happens for bivs which need their
1937 final value set before loop entry. The new register
1938 for the biv was stored in the biv's first struct
1939 induction entry by find_splittable_regs. */
1941 if (regno < max_reg_before_loop
1942 && REG_IV_TYPE (ivs, regno) == BASIC_INDUCT)
1944 giv_src_reg = ivs->reg_biv_class[regno]->biv->src_reg;
1945 giv_dest_reg = giv_src_reg;
1949 /* If non-reduced/final-value givs were split, then
1950 this would have to remap those givs also. See
1951 find_splittable_regs. */
1954 splittable_regs[regno]
1955 = simplify_gen_binary (PLUS, GET_MODE (giv_src_reg),
1957 splittable_regs[src_regno]);
1958 giv_inc = splittable_regs[regno];
1960 /* Now split the induction variable by changing the dest
1961 of this insn to a new register, and setting its
1962 reg_map entry to point to this new register.
1964 If this is the last iteration, and this is the last insn
1965 that will update the iv, then reuse the original dest,
1966 to ensure that the iv will have the proper value when
1967 the loop exits or repeats.
1969 Using splittable_regs_updates here like this is safe,
1970 because it can only be greater than one if all
1971 instructions modifying the iv are always executed in
1974 if (! last_iteration
1975 || (splittable_regs_updates[regno]-- != 1))
1977 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1979 map->reg_map[regno] = tem;
1980 record_base_value (REGNO (tem),
1981 giv_inc == const0_rtx
1983 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1984 giv_src_reg, giv_inc),
1988 map->reg_map[regno] = giv_src_reg;
1991 /* The constant being added could be too large for an add
1992 immediate, so can't directly emit an insn here. */
1993 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1994 copy = get_last_insn ();
1995 pattern = PATTERN (copy);
1999 pattern = copy_rtx_and_substitute (pattern, map, 0);
2000 copy = emit_insn (pattern);
2002 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2005 /* If this insn is setting CC0, it may need to look at
2006 the insn that uses CC0 to see what type of insn it is.
2007 In that case, the call to recog via validate_change will
2008 fail. So don't substitute constants here. Instead,
2009 do it when we emit the following insn.
2011 For example, see the pyr.md file. That machine has signed and
2012 unsigned compares. The compare patterns must check the
2013 following branch insn to see which what kind of compare to
2016 If the previous insn set CC0, substitute constants on it as
2018 if (sets_cc0_p (PATTERN (copy)) != 0)
2023 try_constants (cc0_insn, map);
2025 try_constants (copy, map);
2028 try_constants (copy, map);
2031 /* Make split induction variable constants `permanent' since we
2032 know there are no backward branches across iteration variable
2033 settings which would invalidate this. */
2034 if (dest_reg_was_split)
2036 int regno = REGNO (SET_DEST (set));
2038 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
2039 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
2041 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
2046 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2047 copy = emit_jump_insn (pattern);
2048 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2050 if (JUMP_LABEL (insn) == start_label && insn == copy_end
2051 && ! last_iteration)
2053 /* Update JUMP_LABEL correctly to make invert_jump working. */
2054 JUMP_LABEL (copy) = get_label_from_map (map,
2056 (JUMP_LABEL (insn)));
2057 /* This is a branch to the beginning of the loop; this is the
2058 last insn being copied; and this is not the last iteration.
2059 In this case, we want to change the original fall through
2060 case to be a branch past the end of the loop, and the
2061 original jump label case to fall_through. */
2063 if (!invert_jump (copy, exit_label, 0))
2066 rtx lab = gen_label_rtx ();
2067 /* Can't do it by reversing the jump (probably because we
2068 couldn't reverse the conditions), so emit a new
2069 jump_insn after COPY, and redirect the jump around
2071 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2072 jmp = emit_barrier_after (jmp);
2073 emit_label_after (lab, jmp);
2074 LABEL_NUSES (lab) = 0;
2075 if (!redirect_jump (copy, lab, 0))
2082 try_constants (cc0_insn, map);
2085 try_constants (copy, map);
2087 /* Set the jump label of COPY correctly to avoid problems with
2088 later passes of unroll_loop, if INSN had jump label set. */
2089 if (JUMP_LABEL (insn))
2093 /* Can't use the label_map for every insn, since this may be
2094 the backward branch, and hence the label was not mapped. */
2095 if ((set = single_set (copy)))
2097 tem = SET_SRC (set);
2098 if (GET_CODE (tem) == LABEL_REF)
2099 label = XEXP (tem, 0);
2100 else if (GET_CODE (tem) == IF_THEN_ELSE)
2102 if (XEXP (tem, 1) != pc_rtx)
2103 label = XEXP (XEXP (tem, 1), 0);
2105 label = XEXP (XEXP (tem, 2), 0);
2109 if (label && GET_CODE (label) == CODE_LABEL)
2110 JUMP_LABEL (copy) = label;
2113 /* An unrecognizable jump insn, probably the entry jump
2114 for a switch statement. This label must have been mapped,
2115 so just use the label_map to get the new jump label. */
2117 = get_label_from_map (map,
2118 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2121 /* If this is a non-local jump, then must increase the label
2122 use count so that the label will not be deleted when the
2123 original jump is deleted. */
2124 LABEL_NUSES (JUMP_LABEL (copy))++;
2126 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2127 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2129 rtx pat = PATTERN (copy);
2130 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2131 int len = XVECLEN (pat, diff_vec_p);
2134 for (i = 0; i < len; i++)
2135 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2138 /* If this used to be a conditional jump insn but whose branch
2139 direction is now known, we must do something special. */
2140 if (any_condjump_p (insn) && onlyjump_p (insn) && map->last_pc_value)
2143 /* If the previous insn set cc0 for us, delete it. */
2144 if (sets_cc0_p (PREV_INSN (copy)))
2145 delete_insn (PREV_INSN (copy));
2148 /* If this is now a no-op, delete it. */
2149 if (map->last_pc_value == pc_rtx)
2151 /* Don't let delete_insn delete the label referenced here,
2152 because we might possibly need it later for some other
2153 instruction in the loop. */
2154 if (JUMP_LABEL (copy))
2155 LABEL_NUSES (JUMP_LABEL (copy))++;
2157 if (JUMP_LABEL (copy))
2158 LABEL_NUSES (JUMP_LABEL (copy))--;
2162 /* Otherwise, this is unconditional jump so we must put a
2163 BARRIER after it. We could do some dead code elimination
2164 here, but jump.c will do it just as well. */
2170 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2171 copy = emit_call_insn (pattern);
2172 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2174 /* Because the USAGE information potentially contains objects other
2175 than hard registers, we need to copy it. */
2176 CALL_INSN_FUNCTION_USAGE (copy)
2177 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2182 try_constants (cc0_insn, map);
2185 try_constants (copy, map);
2187 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2188 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2189 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2193 /* If this is the loop start label, then we don't need to emit a
2194 copy of this label since no one will use it. */
2196 if (insn != start_label)
2198 copy = emit_label (get_label_from_map (map,
2199 CODE_LABEL_NUMBER (insn)));
2205 copy = emit_barrier ();
2209 /* VTOP and CONT notes are valid only before the loop exit test.
2210 If placed anywhere else, loop may generate bad code. */
2211 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2212 the associated rtl. We do not want to share the structure in
2215 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2216 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED_LABEL
2217 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2218 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2219 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2220 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2221 copy = emit_note (NOTE_SOURCE_FILE (insn),
2222 NOTE_LINE_NUMBER (insn));
2231 map->insn_map[INSN_UID (insn)] = copy;
2233 while (insn != copy_end);
2235 /* Now finish coping the REG_NOTES. */
2239 insn = NEXT_INSN (insn);
2240 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2241 || GET_CODE (insn) == CALL_INSN)
2242 && map->insn_map[INSN_UID (insn)])
2243 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2245 while (insn != copy_end);
2247 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2248 each of these notes here, since there may be some important ones, such as
2249 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2250 iteration, because the original notes won't be deleted.
2252 We can't use insert_before here, because when from preconditioning,
2253 insert_before points before the loop. We can't use copy_end, because
2254 there may be insns already inserted after it (which we don't want to
2255 copy) when not from preconditioning code. */
2257 if (! last_iteration)
2259 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2261 /* VTOP notes are valid only before the loop exit test.
2262 If placed anywhere else, loop may generate bad code.
2263 There is no need to test for NOTE_INSN_LOOP_CONT notes
2264 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2265 instructions before the last insn in the loop, and if the
2266 end test is that short, there will be a VTOP note between
2267 the CONT note and the test. */
2268 if (GET_CODE (insn) == NOTE
2269 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2270 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2271 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2272 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2276 if (final_label && LABEL_NUSES (final_label) > 0)
2277 emit_label (final_label);
2279 tem = gen_sequence ();
2281 emit_insn_before (tem, insert_before);
2284 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2285 emitted. This will correctly handle the case where the increment value
2286 won't fit in the immediate field of a PLUS insns. */
2289 emit_unrolled_add (dest_reg, src_reg, increment)
2290 rtx dest_reg, src_reg, increment;
2294 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2295 dest_reg, 0, OPTAB_LIB_WIDEN);
2297 if (dest_reg != result)
2298 emit_move_insn (dest_reg, result);
2301 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2302 is a backward branch in that range that branches to somewhere between
2303 LOOP->START and INSN. Returns 0 otherwise. */
2305 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2306 In practice, this is not a problem, because this function is seldom called,
2307 and uses a negligible amount of CPU time on average. */
2310 back_branch_in_range_p (loop, insn)
2311 const struct loop *loop;
2314 rtx p, q, target_insn;
2315 rtx loop_start = loop->start;
2316 rtx loop_end = loop->end;
2317 rtx orig_loop_end = loop->end;
2319 /* Stop before we get to the backward branch at the end of the loop. */
2320 loop_end = prev_nonnote_insn (loop_end);
2321 if (GET_CODE (loop_end) == BARRIER)
2322 loop_end = PREV_INSN (loop_end);
2324 /* Check in case insn has been deleted, search forward for first non
2325 deleted insn following it. */
2326 while (INSN_DELETED_P (insn))
2327 insn = NEXT_INSN (insn);
2329 /* Check for the case where insn is the last insn in the loop. Deal
2330 with the case where INSN was a deleted loop test insn, in which case
2331 it will now be the NOTE_LOOP_END. */
2332 if (insn == loop_end || insn == orig_loop_end)
2335 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2337 if (GET_CODE (p) == JUMP_INSN)
2339 target_insn = JUMP_LABEL (p);
2341 /* Search from loop_start to insn, to see if one of them is
2342 the target_insn. We can't use INSN_LUID comparisons here,
2343 since insn may not have an LUID entry. */
2344 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2345 if (q == target_insn)
2353 /* Try to generate the simplest rtx for the expression
2354 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2358 fold_rtx_mult_add (mult1, mult2, add1, mode)
2359 rtx mult1, mult2, add1;
2360 enum machine_mode mode;
2365 /* The modes must all be the same. This should always be true. For now,
2366 check to make sure. */
2367 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2368 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2369 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2372 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2373 will be a constant. */
2374 if (GET_CODE (mult1) == CONST_INT)
2381 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2383 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2385 /* Again, put the constant second. */
2386 if (GET_CODE (add1) == CONST_INT)
2393 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2395 result = gen_rtx_PLUS (mode, add1, mult_res);
2400 /* Searches the list of induction struct's for the biv BL, to try to calculate
2401 the total increment value for one iteration of the loop as a constant.
2403 Returns the increment value as an rtx, simplified as much as possible,
2404 if it can be calculated. Otherwise, returns 0. */
2407 biv_total_increment (bl)
2408 struct iv_class *bl;
2410 struct induction *v;
2413 /* For increment, must check every instruction that sets it. Each
2414 instruction must be executed only once each time through the loop.
2415 To verify this, we check that the insn is always executed, and that
2416 there are no backward branches after the insn that branch to before it.
2417 Also, the insn must have a mult_val of one (to make sure it really is
2420 result = const0_rtx;
2421 for (v = bl->biv; v; v = v->next_iv)
2423 if (v->always_computable && v->mult_val == const1_rtx
2424 && ! v->maybe_multiple)
2425 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2434 /* For each biv and giv, determine whether it can be safely split into
2435 a different variable for each unrolled copy of the loop body. If it
2436 is safe to split, then indicate that by saving some useful info
2437 in the splittable_regs array.
2439 If the loop is being completely unrolled, then splittable_regs will hold
2440 the current value of the induction variable while the loop is unrolled.
2441 It must be set to the initial value of the induction variable here.
2442 Otherwise, splittable_regs will hold the difference between the current
2443 value of the induction variable and the value the induction variable had
2444 at the top of the loop. It must be set to the value 0 here.
2446 Returns the total number of instructions that set registers that are
2449 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2450 constant values are unnecessary, since we can easily calculate increment
2451 values in this case even if nothing is constant. The increment value
2452 should not involve a multiply however. */
2454 /* ?? Even if the biv/giv increment values aren't constant, it may still
2455 be beneficial to split the variable if the loop is only unrolled a few
2456 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2459 find_splittable_regs (loop, unroll_type, end_insert_before, unroll_number)
2460 const struct loop *loop;
2461 enum unroll_types unroll_type;
2462 rtx end_insert_before;
2465 struct loop_ivs *ivs = LOOP_IVS (loop);
2466 struct iv_class *bl;
2467 struct induction *v;
2469 rtx biv_final_value;
2472 rtx loop_start = loop->start;
2473 rtx loop_end = loop->end;
2475 for (bl = ivs->loop_iv_list; bl; bl = bl->next)
2477 /* Biv_total_increment must return a constant value,
2478 otherwise we can not calculate the split values. */
2480 increment = biv_total_increment (bl);
2481 if (! increment || GET_CODE (increment) != CONST_INT)
2484 /* The loop must be unrolled completely, or else have a known number
2485 of iterations and only one exit, or else the biv must be dead
2486 outside the loop, or else the final value must be known. Otherwise,
2487 it is unsafe to split the biv since it may not have the proper
2488 value on loop exit. */
2490 /* loop_number_exit_count is non-zero if the loop has an exit other than
2491 a fall through at the end. */
2494 biv_final_value = 0;
2495 if (unroll_type != UNROLL_COMPLETELY
2496 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2497 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2499 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2500 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2501 < INSN_LUID (bl->init_insn))
2502 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2503 && ! (biv_final_value = final_biv_value (loop, bl)))
2506 /* If any of the insns setting the BIV don't do so with a simple
2507 PLUS, we don't know how to split it. */
2508 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2509 if ((tem = single_set (v->insn)) == 0
2510 || GET_CODE (SET_DEST (tem)) != REG
2511 || REGNO (SET_DEST (tem)) != bl->regno
2512 || GET_CODE (SET_SRC (tem)) != PLUS)
2515 /* If final value is non-zero, then must emit an instruction which sets
2516 the value of the biv to the proper value. This is done after
2517 handling all of the givs, since some of them may need to use the
2518 biv's value in their initialization code. */
2520 /* This biv is splittable. If completely unrolling the loop, save
2521 the biv's initial value. Otherwise, save the constant zero. */
2523 if (biv_splittable == 1)
2525 if (unroll_type == UNROLL_COMPLETELY)
2527 /* If the initial value of the biv is itself (i.e. it is too
2528 complicated for strength_reduce to compute), or is a hard
2529 register, or it isn't invariant, then we must create a new
2530 pseudo reg to hold the initial value of the biv. */
2532 if (GET_CODE (bl->initial_value) == REG
2533 && (REGNO (bl->initial_value) == bl->regno
2534 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2535 || ! loop_invariant_p (loop, bl->initial_value)))
2537 rtx tem = gen_reg_rtx (bl->biv->mode);
2539 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2540 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2543 if (loop_dump_stream)
2544 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2545 bl->regno, REGNO (tem));
2547 splittable_regs[bl->regno] = tem;
2550 splittable_regs[bl->regno] = bl->initial_value;
2553 splittable_regs[bl->regno] = const0_rtx;
2555 /* Save the number of instructions that modify the biv, so that
2556 we can treat the last one specially. */
2558 splittable_regs_updates[bl->regno] = bl->biv_count;
2559 result += bl->biv_count;
2561 if (loop_dump_stream)
2562 fprintf (loop_dump_stream,
2563 "Biv %d safe to split.\n", bl->regno);
2566 /* Check every giv that depends on this biv to see whether it is
2567 splittable also. Even if the biv isn't splittable, givs which
2568 depend on it may be splittable if the biv is live outside the
2569 loop, and the givs aren't. */
2571 result += find_splittable_givs (loop, bl, unroll_type, increment,
2574 /* If final value is non-zero, then must emit an instruction which sets
2575 the value of the biv to the proper value. This is done after
2576 handling all of the givs, since some of them may need to use the
2577 biv's value in their initialization code. */
2578 if (biv_final_value)
2580 /* If the loop has multiple exits, emit the insns before the
2581 loop to ensure that it will always be executed no matter
2582 how the loop exits. Otherwise emit the insn after the loop,
2583 since this is slightly more efficient. */
2584 if (! loop->exit_count)
2585 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2590 /* Create a new register to hold the value of the biv, and then
2591 set the biv to its final value before the loop start. The biv
2592 is set to its final value before loop start to ensure that
2593 this insn will always be executed, no matter how the loop
2595 rtx tem = gen_reg_rtx (bl->biv->mode);
2596 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2598 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2600 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2604 if (loop_dump_stream)
2605 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2606 REGNO (bl->biv->src_reg), REGNO (tem));
2608 /* Set up the mapping from the original biv register to the new
2610 bl->biv->src_reg = tem;
2617 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2618 for the instruction that is using it. Do not make any changes to that
2622 verify_addresses (v, giv_inc, unroll_number)
2623 struct induction *v;
2628 rtx orig_addr = *v->location;
2629 rtx last_addr = plus_constant (v->dest_reg,
2630 INTVAL (giv_inc) * (unroll_number - 1));
2632 /* First check to see if either address would fail. Handle the fact
2633 that we have may have a match_dup. */
2634 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2635 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2638 /* Now put things back the way they were before. This should always
2640 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2646 /* For every giv based on the biv BL, check to determine whether it is
2647 splittable. This is a subroutine to find_splittable_regs ().
2649 Return the number of instructions that set splittable registers. */
2652 find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
2653 const struct loop *loop;
2654 struct iv_class *bl;
2655 enum unroll_types unroll_type;
2659 struct loop_ivs *ivs = LOOP_IVS (loop);
2660 struct induction *v, *v2;
2665 /* Scan the list of givs, and set the same_insn field when there are
2666 multiple identical givs in the same insn. */
2667 for (v = bl->giv; v; v = v->next_iv)
2668 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2669 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2673 for (v = bl->giv; v; v = v->next_iv)
2677 /* Only split the giv if it has already been reduced, or if the loop is
2678 being completely unrolled. */
2679 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2682 /* The giv can be split if the insn that sets the giv is executed once
2683 and only once on every iteration of the loop. */
2684 /* An address giv can always be split. v->insn is just a use not a set,
2685 and hence it does not matter whether it is always executed. All that
2686 matters is that all the biv increments are always executed, and we
2687 won't reach here if they aren't. */
2688 if (v->giv_type != DEST_ADDR
2689 && (! v->always_computable
2690 || back_branch_in_range_p (loop, v->insn)))
2693 /* The giv increment value must be a constant. */
2694 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2696 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2699 /* The loop must be unrolled completely, or else have a known number of
2700 iterations and only one exit, or else the giv must be dead outside
2701 the loop, or else the final value of the giv must be known.
2702 Otherwise, it is not safe to split the giv since it may not have the
2703 proper value on loop exit. */
2705 /* The used outside loop test will fail for DEST_ADDR givs. They are
2706 never used outside the loop anyways, so it is always safe to split a
2710 if (unroll_type != UNROLL_COMPLETELY
2711 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2712 && v->giv_type != DEST_ADDR
2713 /* The next part is true if the pseudo is used outside the loop.
2714 We assume that this is true for any pseudo created after loop
2715 starts, because we don't have a reg_n_info entry for them. */
2716 && (REGNO (v->dest_reg) >= max_reg_before_loop
2717 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2718 /* Check for the case where the pseudo is set by a shift/add
2719 sequence, in which case the first insn setting the pseudo
2720 is the first insn of the shift/add sequence. */
2721 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2722 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2723 != INSN_UID (XEXP (tem, 0)))))
2724 /* Line above always fails if INSN was moved by loop opt. */
2725 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2726 >= INSN_LUID (loop->end)))
2727 /* Givs made from biv increments are missed by the above test, so
2728 test explicitly for them. */
2729 && (REGNO (v->dest_reg) < ivs->first_increment_giv
2730 || REGNO (v->dest_reg) > ivs->last_increment_giv)
2731 && ! (final_value = v->final_value))
2735 /* Currently, non-reduced/final-value givs are never split. */
2736 /* Should emit insns after the loop if possible, as the biv final value
2739 /* If the final value is non-zero, and the giv has not been reduced,
2740 then must emit an instruction to set the final value. */
2741 if (final_value && !v->new_reg)
2743 /* Create a new register to hold the value of the giv, and then set
2744 the giv to its final value before the loop start. The giv is set
2745 to its final value before loop start to ensure that this insn
2746 will always be executed, no matter how we exit. */
2747 tem = gen_reg_rtx (v->mode);
2748 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2749 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2752 if (loop_dump_stream)
2753 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2754 REGNO (v->dest_reg), REGNO (tem));
2760 /* This giv is splittable. If completely unrolling the loop, save the
2761 giv's initial value. Otherwise, save the constant zero for it. */
2763 if (unroll_type == UNROLL_COMPLETELY)
2765 /* It is not safe to use bl->initial_value here, because it may not
2766 be invariant. It is safe to use the initial value stored in
2767 the splittable_regs array if it is set. In rare cases, it won't
2768 be set, so then we do exactly the same thing as
2769 find_splittable_regs does to get a safe value. */
2770 rtx biv_initial_value;
2772 if (splittable_regs[bl->regno])
2773 biv_initial_value = splittable_regs[bl->regno];
2774 else if (GET_CODE (bl->initial_value) != REG
2775 || (REGNO (bl->initial_value) != bl->regno
2776 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2777 biv_initial_value = bl->initial_value;
2780 rtx tem = gen_reg_rtx (bl->biv->mode);
2782 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2783 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2785 biv_initial_value = tem;
2787 biv_initial_value = extend_value_for_giv (v, biv_initial_value);
2788 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2789 v->add_val, v->mode);
2796 /* If a giv was combined with another giv, then we can only split
2797 this giv if the giv it was combined with was reduced. This
2798 is because the value of v->new_reg is meaningless in this
2800 if (v->same && ! v->same->new_reg)
2802 if (loop_dump_stream)
2803 fprintf (loop_dump_stream,
2804 "giv combined with unreduced giv not split.\n");
2807 /* If the giv is an address destination, it could be something other
2808 than a simple register, these have to be treated differently. */
2809 else if (v->giv_type == DEST_REG)
2811 /* If value is not a constant, register, or register plus
2812 constant, then compute its value into a register before
2813 loop start. This prevents invalid rtx sharing, and should
2814 generate better code. We can use bl->initial_value here
2815 instead of splittable_regs[bl->regno] because this code
2816 is going before the loop start. */
2817 if (unroll_type == UNROLL_COMPLETELY
2818 && GET_CODE (value) != CONST_INT
2819 && GET_CODE (value) != REG
2820 && (GET_CODE (value) != PLUS
2821 || GET_CODE (XEXP (value, 0)) != REG
2822 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2824 rtx tem = gen_reg_rtx (v->mode);
2825 record_base_value (REGNO (tem), v->add_val, 0);
2826 emit_iv_add_mult (bl->initial_value, v->mult_val,
2827 v->add_val, tem, loop->start);
2831 splittable_regs[REGNO (v->new_reg)] = value;
2832 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2836 /* Splitting address givs is useful since it will often allow us
2837 to eliminate some increment insns for the base giv as
2840 /* If the addr giv is combined with a dest_reg giv, then all
2841 references to that dest reg will be remapped, which is NOT
2842 what we want for split addr regs. We always create a new
2843 register for the split addr giv, just to be safe. */
2845 /* If we have multiple identical address givs within a
2846 single instruction, then use a single pseudo reg for
2847 both. This is necessary in case one is a match_dup
2850 v->const_adjust = 0;
2854 v->dest_reg = v->same_insn->dest_reg;
2855 if (loop_dump_stream)
2856 fprintf (loop_dump_stream,
2857 "Sharing address givs in insn %d\n",
2858 INSN_UID (v->insn));
2860 /* If multiple address GIVs have been combined with the
2861 same dest_reg GIV, do not create a new register for
2863 else if (unroll_type != UNROLL_COMPLETELY
2864 && v->giv_type == DEST_ADDR
2865 && v->same && v->same->giv_type == DEST_ADDR
2866 && v->same->unrolled
2867 /* combine_givs_p may return true for some cases
2868 where the add and mult values are not equal.
2869 To share a register here, the values must be
2871 && rtx_equal_p (v->same->mult_val, v->mult_val)
2872 && rtx_equal_p (v->same->add_val, v->add_val)
2873 /* If the memory references have different modes,
2874 then the address may not be valid and we must
2875 not share registers. */
2876 && verify_addresses (v, giv_inc, unroll_number))
2878 v->dest_reg = v->same->dest_reg;
2881 else if (unroll_type != UNROLL_COMPLETELY)
2883 /* If not completely unrolling the loop, then create a new
2884 register to hold the split value of the DEST_ADDR giv.
2885 Emit insn to initialize its value before loop start. */
2887 rtx tem = gen_reg_rtx (v->mode);
2888 struct induction *same = v->same;
2889 rtx new_reg = v->new_reg;
2890 record_base_value (REGNO (tem), v->add_val, 0);
2892 if (same && same->derived_from)
2894 /* calculate_giv_inc doesn't work for derived givs.
2895 copy_loop_body works around the problem for the
2896 DEST_REG givs themselves, but it can't handle
2897 DEST_ADDR givs that have been combined with
2898 a derived DEST_REG giv.
2899 So Handle V as if the giv from which V->SAME has
2900 been derived has been combined with V.
2901 recombine_givs only derives givs from givs that
2902 are reduced the ordinary, so we need not worry
2903 about same->derived_from being in turn derived. */
2905 same = same->derived_from;
2906 new_reg = express_from (same, v);
2907 new_reg = replace_rtx (new_reg, same->dest_reg,
2911 /* If the address giv has a constant in its new_reg value,
2912 then this constant can be pulled out and put in value,
2913 instead of being part of the initialization code. */
2915 if (GET_CODE (new_reg) == PLUS
2916 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
2919 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
2921 /* Only succeed if this will give valid addresses.
2922 Try to validate both the first and the last
2923 address resulting from loop unrolling, if
2924 one fails, then can't do const elim here. */
2925 if (verify_addresses (v, giv_inc, unroll_number))
2927 /* Save the negative of the eliminated const, so
2928 that we can calculate the dest_reg's increment
2930 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
2932 new_reg = XEXP (new_reg, 0);
2933 if (loop_dump_stream)
2934 fprintf (loop_dump_stream,
2935 "Eliminating constant from giv %d\n",
2944 /* If the address hasn't been checked for validity yet, do so
2945 now, and fail completely if either the first or the last
2946 unrolled copy of the address is not a valid address
2947 for the instruction that uses it. */
2948 if (v->dest_reg == tem
2949 && ! verify_addresses (v, giv_inc, unroll_number))
2951 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2952 if (v2->same_insn == v)
2955 if (loop_dump_stream)
2956 fprintf (loop_dump_stream,
2957 "Invalid address for giv at insn %d\n",
2958 INSN_UID (v->insn));
2962 v->new_reg = new_reg;
2965 /* We set this after the address check, to guarantee that
2966 the register will be initialized. */
2969 /* To initialize the new register, just move the value of
2970 new_reg into it. This is not guaranteed to give a valid
2971 instruction on machines with complex addressing modes.
2972 If we can't recognize it, then delete it and emit insns
2973 to calculate the value from scratch. */
2974 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
2975 copy_rtx (v->new_reg)),
2977 if (recog_memoized (PREV_INSN (loop->start)) < 0)
2981 /* We can't use bl->initial_value to compute the initial
2982 value, because the loop may have been preconditioned.
2983 We must calculate it from NEW_REG. Try using
2984 force_operand instead of emit_iv_add_mult. */
2985 delete_insn (PREV_INSN (loop->start));
2988 ret = force_operand (v->new_reg, tem);
2990 emit_move_insn (tem, ret);
2991 sequence = gen_sequence ();
2993 emit_insn_before (sequence, loop->start);
2995 if (loop_dump_stream)
2996 fprintf (loop_dump_stream,
2997 "Invalid init insn, rewritten.\n");
3002 v->dest_reg = value;
3004 /* Check the resulting address for validity, and fail
3005 if the resulting address would be invalid. */
3006 if (! verify_addresses (v, giv_inc, unroll_number))
3008 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3009 if (v2->same_insn == v)
3012 if (loop_dump_stream)
3013 fprintf (loop_dump_stream,
3014 "Invalid address for giv at insn %d\n",
3015 INSN_UID (v->insn));
3018 if (v->same && v->same->derived_from)
3020 /* Handle V as if the giv from which V->SAME has
3021 been derived has been combined with V. */
3023 v->same = v->same->derived_from;
3024 v->new_reg = express_from (v->same, v);
3025 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3031 /* Store the value of dest_reg into the insn. This sharing
3032 will not be a problem as this insn will always be copied
3035 *v->location = v->dest_reg;
3037 /* If this address giv is combined with a dest reg giv, then
3038 save the base giv's induction pointer so that we will be
3039 able to handle this address giv properly. The base giv
3040 itself does not have to be splittable. */
3042 if (v->same && v->same->giv_type == DEST_REG)
3043 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3045 if (GET_CODE (v->new_reg) == REG)
3047 /* This giv maybe hasn't been combined with any others.
3048 Make sure that it's giv is marked as splittable here. */
3050 splittable_regs[REGNO (v->new_reg)] = value;
3051 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3053 /* Make it appear to depend upon itself, so that the
3054 giv will be properly split in the main loop above. */
3058 addr_combined_regs[REGNO (v->new_reg)] = v;
3062 if (loop_dump_stream)
3063 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3069 /* Currently, unreduced giv's can't be split. This is not too much
3070 of a problem since unreduced giv's are not live across loop
3071 iterations anyways. When unrolling a loop completely though,
3072 it makes sense to reduce&split givs when possible, as this will
3073 result in simpler instructions, and will not require that a reg
3074 be live across loop iterations. */
3076 splittable_regs[REGNO (v->dest_reg)] = value;
3077 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3078 REGNO (v->dest_reg), INSN_UID (v->insn));
3084 /* Unreduced givs are only updated once by definition. Reduced givs
3085 are updated as many times as their biv is. Mark it so if this is
3086 a splittable register. Don't need to do anything for address givs
3087 where this may not be a register. */
3089 if (GET_CODE (v->new_reg) == REG)
3093 count = ivs->reg_biv_class[REGNO (v->src_reg)]->biv_count;
3095 if (count > 1 && v->derived_from)
3096 /* In this case, there is one set where the giv insn was and one
3097 set each after each biv increment. (Most are likely dead.) */
3100 splittable_regs_updates[REGNO (v->new_reg)] = count;
3105 if (loop_dump_stream)
3109 if (GET_CODE (v->dest_reg) == CONST_INT)
3111 else if (GET_CODE (v->dest_reg) != REG)
3112 regnum = REGNO (XEXP (v->dest_reg, 0));
3114 regnum = REGNO (v->dest_reg);
3115 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3116 regnum, INSN_UID (v->insn));
3123 /* Try to prove that the register is dead after the loop exits. Trace every
3124 loop exit looking for an insn that will always be executed, which sets
3125 the register to some value, and appears before the first use of the register
3126 is found. If successful, then return 1, otherwise return 0. */
3128 /* ?? Could be made more intelligent in the handling of jumps, so that
3129 it can search past if statements and other similar structures. */
3132 reg_dead_after_loop (loop, reg)
3133 const struct loop *loop;
3139 int label_count = 0;
3141 /* In addition to checking all exits of this loop, we must also check
3142 all exits of inner nested loops that would exit this loop. We don't
3143 have any way to identify those, so we just give up if there are any
3144 such inner loop exits. */
3146 for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
3149 if (label_count != loop->exit_count)
3152 /* HACK: Must also search the loop fall through exit, create a label_ref
3153 here which points to the loop->end, and append the loop_number_exit_labels
3155 label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
3156 LABEL_NEXTREF (label) = loop->exit_labels;
3158 for ( ; label; label = LABEL_NEXTREF (label))
3160 /* Succeed if find an insn which sets the biv or if reach end of
3161 function. Fail if find an insn that uses the biv, or if come to
3162 a conditional jump. */
3164 insn = NEXT_INSN (XEXP (label, 0));
3167 code = GET_CODE (insn);
3168 if (GET_RTX_CLASS (code) == 'i')
3172 if (reg_referenced_p (reg, PATTERN (insn)))
3175 set = single_set (insn);
3176 if (set && rtx_equal_p (SET_DEST (set), reg))
3180 if (code == JUMP_INSN)
3182 if (GET_CODE (PATTERN (insn)) == RETURN)
3184 else if (!any_uncondjump_p (insn)
3185 /* Prevent infinite loop following infinite loops. */
3186 || jump_count++ > 20)
3189 insn = JUMP_LABEL (insn);
3192 insn = NEXT_INSN (insn);
3196 /* Success, the register is dead on all loop exits. */
3200 /* Try to calculate the final value of the biv, the value it will have at
3201 the end of the loop. If we can do it, return that value. */
3204 final_biv_value (loop, bl)
3205 const struct loop *loop;
3206 struct iv_class *bl;
3208 rtx loop_end = loop->end;
3209 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3212 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3214 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3217 /* The final value for reversed bivs must be calculated differently than
3218 for ordinary bivs. In this case, there is already an insn after the
3219 loop which sets this biv's final value (if necessary), and there are
3220 no other loop exits, so we can return any value. */
3223 if (loop_dump_stream)
3224 fprintf (loop_dump_stream,
3225 "Final biv value for %d, reversed biv.\n", bl->regno);
3230 /* Try to calculate the final value as initial value + (number of iterations
3231 * increment). For this to work, increment must be invariant, the only
3232 exit from the loop must be the fall through at the bottom (otherwise
3233 it may not have its final value when the loop exits), and the initial
3234 value of the biv must be invariant. */
3236 if (n_iterations != 0
3237 && ! loop->exit_count
3238 && loop_invariant_p (loop, bl->initial_value))
3240 increment = biv_total_increment (bl);
3242 if (increment && loop_invariant_p (loop, increment))
3244 /* Can calculate the loop exit value, emit insns after loop
3245 end to calculate this value into a temporary register in
3246 case it is needed later. */
3248 tem = gen_reg_rtx (bl->biv->mode);
3249 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3250 /* Make sure loop_end is not the last insn. */
3251 if (NEXT_INSN (loop_end) == 0)
3252 emit_note_after (NOTE_INSN_DELETED, loop_end);
3253 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3254 bl->initial_value, tem, NEXT_INSN (loop_end));
3256 if (loop_dump_stream)
3257 fprintf (loop_dump_stream,
3258 "Final biv value for %d, calculated.\n", bl->regno);
3264 /* Check to see if the biv is dead at all loop exits. */
3265 if (reg_dead_after_loop (loop, bl->biv->src_reg))
3267 if (loop_dump_stream)
3268 fprintf (loop_dump_stream,
3269 "Final biv value for %d, biv dead after loop exit.\n",
3278 /* Try to calculate the final value of the giv, the value it will have at
3279 the end of the loop. If we can do it, return that value. */
3282 final_giv_value (loop, v)
3283 const struct loop *loop;
3284 struct induction *v;
3286 struct loop_ivs *ivs = LOOP_IVS (loop);
3287 struct iv_class *bl;
3290 rtx insert_before, seq;
3291 rtx loop_end = loop->end;
3292 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3294 bl = ivs->reg_biv_class[REGNO (v->src_reg)];
3296 /* The final value for givs which depend on reversed bivs must be calculated
3297 differently than for ordinary givs. In this case, there is already an
3298 insn after the loop which sets this giv's final value (if necessary),
3299 and there are no other loop exits, so we can return any value. */
3302 if (loop_dump_stream)
3303 fprintf (loop_dump_stream,
3304 "Final giv value for %d, depends on reversed biv\n",
3305 REGNO (v->dest_reg));
3309 /* Try to calculate the final value as a function of the biv it depends
3310 upon. The only exit from the loop must be the fall through at the bottom
3311 (otherwise it may not have its final value when the loop exits). */
3313 /* ??? Can calculate the final giv value by subtracting off the
3314 extra biv increments times the giv's mult_val. The loop must have
3315 only one exit for this to work, but the loop iterations does not need
3318 if (n_iterations != 0
3319 && ! loop->exit_count)
3321 /* ?? It is tempting to use the biv's value here since these insns will
3322 be put after the loop, and hence the biv will have its final value
3323 then. However, this fails if the biv is subsequently eliminated.
3324 Perhaps determine whether biv's are eliminable before trying to
3325 determine whether giv's are replaceable so that we can use the
3326 biv value here if it is not eliminable. */
3328 /* We are emitting code after the end of the loop, so we must make
3329 sure that bl->initial_value is still valid then. It will still
3330 be valid if it is invariant. */
3332 increment = biv_total_increment (bl);
3334 if (increment && loop_invariant_p (loop, increment)
3335 && loop_invariant_p (loop, bl->initial_value))
3337 /* Can calculate the loop exit value of its biv as
3338 (n_iterations * increment) + initial_value */
3340 /* The loop exit value of the giv is then
3341 (final_biv_value - extra increments) * mult_val + add_val.
3342 The extra increments are any increments to the biv which
3343 occur in the loop after the giv's value is calculated.
3344 We must search from the insn that sets the giv to the end
3345 of the loop to calculate this value. */
3347 insert_before = NEXT_INSN (loop_end);
3349 /* Put the final biv value in tem. */
3350 tem = gen_reg_rtx (v->mode);
3351 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3352 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3353 extend_value_for_giv (v, bl->initial_value),
3354 tem, insert_before);
3356 /* Subtract off extra increments as we find them. */
3357 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3358 insn = NEXT_INSN (insn))
3360 struct induction *biv;
3362 for (biv = bl->biv; biv; biv = biv->next_iv)
3363 if (biv->insn == insn)
3366 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3367 biv->add_val, NULL_RTX, 0,
3369 seq = gen_sequence ();
3371 emit_insn_before (seq, insert_before);
3375 /* Now calculate the giv's final value. */
3376 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3379 if (loop_dump_stream)
3380 fprintf (loop_dump_stream,
3381 "Final giv value for %d, calc from biv's value.\n",
3382 REGNO (v->dest_reg));
3388 /* Replaceable giv's should never reach here. */
3392 /* Check to see if the biv is dead at all loop exits. */
3393 if (reg_dead_after_loop (loop, v->dest_reg))
3395 if (loop_dump_stream)
3396 fprintf (loop_dump_stream,
3397 "Final giv value for %d, giv dead after loop exit.\n",
3398 REGNO (v->dest_reg));
3407 /* Look back before LOOP->START for then insn that sets REG and return
3408 the equivalent constant if there is a REG_EQUAL note otherwise just
3409 the SET_SRC of REG. */
3412 loop_find_equiv_value (loop, reg)
3413 const struct loop *loop;
3416 rtx loop_start = loop->start;
3421 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3423 if (GET_CODE (insn) == CODE_LABEL)
3426 else if (INSN_P (insn) && reg_set_p (reg, insn))
3428 /* We found the last insn before the loop that sets the register.
3429 If it sets the entire register, and has a REG_EQUAL note,
3430 then use the value of the REG_EQUAL note. */
3431 if ((set = single_set (insn))
3432 && (SET_DEST (set) == reg))
3434 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3436 /* Only use the REG_EQUAL note if it is a constant.
3437 Other things, divide in particular, will cause
3438 problems later if we use them. */
3439 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3440 && CONSTANT_P (XEXP (note, 0)))
3441 ret = XEXP (note, 0);
3443 ret = SET_SRC (set);
3445 /* We cannot do this if it changes between the
3446 assignment and loop start though. */
3447 if (modified_between_p (ret, insn, loop_start))
3456 /* Return a simplified rtx for the expression OP - REG.
3458 REG must appear in OP, and OP must be a register or the sum of a register
3461 Thus, the return value must be const0_rtx or the second term.
3463 The caller is responsible for verifying that REG appears in OP and OP has
3467 subtract_reg_term (op, reg)
3472 if (GET_CODE (op) == PLUS)
3474 if (XEXP (op, 0) == reg)
3475 return XEXP (op, 1);
3476 else if (XEXP (op, 1) == reg)
3477 return XEXP (op, 0);
3479 /* OP does not contain REG as a term. */
3484 /* Find and return register term common to both expressions OP0 and
3485 OP1 or NULL_RTX if no such term exists. Each expression must be a
3486 REG or a PLUS of a REG. */
3489 find_common_reg_term (op0, op1)
3492 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3493 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3500 if (GET_CODE (op0) == PLUS)
3501 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3503 op01 = const0_rtx, op00 = op0;
3505 if (GET_CODE (op1) == PLUS)
3506 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3508 op11 = const0_rtx, op10 = op1;
3510 /* Find and return common register term if present. */
3511 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3513 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3517 /* No common register term found. */
3522 /* Determine the loop iterator and calculate the number of loop
3523 iterations. Returns the exact number of loop iterations if it can
3524 be calculated, otherwise returns zero. */
3526 unsigned HOST_WIDE_INT
3527 loop_iterations (loop)
3530 struct loop_info *loop_info = LOOP_INFO (loop);
3531 struct loop_ivs *ivs = LOOP_IVS (loop);
3532 rtx comparison, comparison_value;
3533 rtx iteration_var, initial_value, increment, final_value;
3534 enum rtx_code comparison_code;
3535 HOST_WIDE_INT abs_inc;
3536 unsigned HOST_WIDE_INT abs_diff;
3539 int unsigned_p, compare_dir, final_larger;
3542 struct iv_class *bl;
3544 loop_info->n_iterations = 0;
3545 loop_info->initial_value = 0;
3546 loop_info->initial_equiv_value = 0;
3547 loop_info->comparison_value = 0;
3548 loop_info->final_value = 0;
3549 loop_info->final_equiv_value = 0;
3550 loop_info->increment = 0;
3551 loop_info->iteration_var = 0;
3552 loop_info->unroll_number = 1;
3555 /* We used to use prev_nonnote_insn here, but that fails because it might
3556 accidentally get the branch for a contained loop if the branch for this
3557 loop was deleted. We can only trust branches immediately before the
3559 last_loop_insn = PREV_INSN (loop->end);
3561 /* ??? We should probably try harder to find the jump insn
3562 at the end of the loop. The following code assumes that
3563 the last loop insn is a jump to the top of the loop. */
3564 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3566 if (loop_dump_stream)
3567 fprintf (loop_dump_stream,
3568 "Loop iterations: No final conditional branch found.\n");
3572 /* If there is a more than a single jump to the top of the loop
3573 we cannot (easily) determine the iteration count. */
3574 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3576 if (loop_dump_stream)
3577 fprintf (loop_dump_stream,
3578 "Loop iterations: Loop has multiple back edges.\n");
3582 /* Find the iteration variable. If the last insn is a conditional
3583 branch, and the insn before tests a register value, make that the
3584 iteration variable. */
3586 comparison = get_condition_for_loop (loop, last_loop_insn);
3587 if (comparison == 0)
3589 if (loop_dump_stream)
3590 fprintf (loop_dump_stream,
3591 "Loop iterations: No final comparison found.\n");
3595 /* ??? Get_condition may switch position of induction variable and
3596 invariant register when it canonicalizes the comparison. */
3598 comparison_code = GET_CODE (comparison);
3599 iteration_var = XEXP (comparison, 0);
3600 comparison_value = XEXP (comparison, 1);
3602 if (GET_CODE (iteration_var) != REG)
3604 if (loop_dump_stream)
3605 fprintf (loop_dump_stream,
3606 "Loop iterations: Comparison not against register.\n");
3610 /* The only new registers that are created before loop iterations
3611 are givs made from biv increments or registers created by
3612 load_mems. In the latter case, it is possible that try_copy_prop
3613 will propagate a new pseudo into the old iteration register but
3614 this will be marked by having the REG_USERVAR_P bit set. */
3616 if ((unsigned) REGNO (iteration_var) >= ivs->reg_iv_type->num_elements
3617 && ! REG_USERVAR_P (iteration_var))
3620 /* Determine the initial value of the iteration variable, and the amount
3621 that it is incremented each loop. Use the tables constructed by
3622 the strength reduction pass to calculate these values. */
3624 /* Clear the result values, in case no answer can be found. */
3628 /* The iteration variable can be either a giv or a biv. Check to see
3629 which it is, and compute the variable's initial value, and increment
3630 value if possible. */
3632 /* If this is a new register, can't handle it since we don't have any
3633 reg_iv_type entry for it. */
3634 if ((unsigned) REGNO (iteration_var) >= ivs->reg_iv_type->num_elements)
3636 if (loop_dump_stream)
3637 fprintf (loop_dump_stream,
3638 "Loop iterations: No reg_iv_type entry for iteration var.\n");
3642 /* Reject iteration variables larger than the host wide int size, since they
3643 could result in a number of iterations greater than the range of our
3644 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
3645 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
3646 > HOST_BITS_PER_WIDE_INT))
3648 if (loop_dump_stream)
3649 fprintf (loop_dump_stream,
3650 "Loop iterations: Iteration var rejected because mode too large.\n");
3653 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
3655 if (loop_dump_stream)
3656 fprintf (loop_dump_stream,
3657 "Loop iterations: Iteration var not an integer.\n");
3660 else if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == BASIC_INDUCT)
3662 /* When reg_iv_type / reg_iv_info is resized for biv increments
3663 that are turned into givs, reg_biv_class is not resized.
3664 So check here that we don't make an out-of-bounds access. */
3665 if (REGNO (iteration_var) >= max_reg_before_loop)
3668 /* Grab initial value, only useful if it is a constant. */
3669 bl = ivs->reg_biv_class[REGNO (iteration_var)];
3670 initial_value = bl->initial_value;
3672 increment = biv_total_increment (bl);
3674 else if (REG_IV_TYPE (ivs, REGNO (iteration_var)) == GENERAL_INDUCT)
3676 HOST_WIDE_INT offset = 0;
3677 struct induction *v = REG_IV_INFO (ivs, REGNO (iteration_var));
3678 rtx biv_initial_value;
3680 if (REGNO (v->src_reg) >= max_reg_before_loop)
3683 bl = ivs->reg_biv_class[REGNO (v->src_reg)];
3685 /* Increment value is mult_val times the increment value of the biv. */
3687 increment = biv_total_increment (bl);
3690 struct induction *biv_inc;
3693 = fold_rtx_mult_add (v->mult_val, increment, const0_rtx, v->mode);
3694 /* The caller assumes that one full increment has occured at the
3695 first loop test. But that's not true when the biv is incremented
3696 after the giv is set (which is the usual case), e.g.:
3697 i = 6; do {;} while (i++ < 9) .
3698 Therefore, we bias the initial value by subtracting the amount of
3699 the increment that occurs between the giv set and the giv test. */
3700 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
3702 if (loop_insn_first_p (v->insn, biv_inc->insn))
3703 offset -= INTVAL (biv_inc->add_val);
3705 offset *= INTVAL (v->mult_val);
3707 if (loop_dump_stream)
3708 fprintf (loop_dump_stream,
3709 "Loop iterations: Giv iterator, initial value bias %ld.\n",
3712 /* Initial value is mult_val times the biv's initial value plus
3713 add_val. Only useful if it is a constant. */
3714 biv_initial_value = extend_value_for_giv (v, bl->initial_value);
3716 = fold_rtx_mult_add (v->mult_val,
3717 plus_constant (biv_initial_value, offset),
3718 v->add_val, v->mode);
3722 if (loop_dump_stream)
3723 fprintf (loop_dump_stream,
3724 "Loop iterations: Not basic or general induction var.\n");
3728 if (initial_value == 0)
3733 switch (comparison_code)
3748 /* Cannot determine loop iterations with this case. */
3767 /* If the comparison value is an invariant register, then try to find
3768 its value from the insns before the start of the loop. */
3770 final_value = comparison_value;
3771 if (GET_CODE (comparison_value) == REG
3772 && loop_invariant_p (loop, comparison_value))
3774 final_value = loop_find_equiv_value (loop, comparison_value);
3776 /* If we don't get an invariant final value, we are better
3777 off with the original register. */
3778 if (! loop_invariant_p (loop, final_value))
3779 final_value = comparison_value;
3782 /* Calculate the approximate final value of the induction variable
3783 (on the last successful iteration). The exact final value
3784 depends on the branch operator, and increment sign. It will be
3785 wrong if the iteration variable is not incremented by one each
3786 time through the loop and (comparison_value + off_by_one -
3787 initial_value) % increment != 0.
3788 ??? Note that the final_value may overflow and thus final_larger
3789 will be bogus. A potentially infinite loop will be classified
3790 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3792 final_value = plus_constant (final_value, off_by_one);
3794 /* Save the calculated values describing this loop's bounds, in case
3795 precondition_loop_p will need them later. These values can not be
3796 recalculated inside precondition_loop_p because strength reduction
3797 optimizations may obscure the loop's structure.
3799 These values are only required by precondition_loop_p and insert_bct
3800 whenever the number of iterations cannot be computed at compile time.
3801 Only the difference between final_value and initial_value is
3802 important. Note that final_value is only approximate. */
3803 loop_info->initial_value = initial_value;
3804 loop_info->comparison_value = comparison_value;
3805 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3806 loop_info->increment = increment;
3807 loop_info->iteration_var = iteration_var;
3808 loop_info->comparison_code = comparison_code;
3811 /* Try to determine the iteration count for loops such
3812 as (for i = init; i < init + const; i++). When running the
3813 loop optimization twice, the first pass often converts simple
3814 loops into this form. */
3816 if (REG_P (initial_value))
3822 reg1 = initial_value;
3823 if (GET_CODE (final_value) == PLUS)
3824 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3826 reg2 = final_value, const2 = const0_rtx;
3828 /* Check for initial_value = reg1, final_value = reg2 + const2,
3829 where reg1 != reg2. */
3830 if (REG_P (reg2) && reg2 != reg1)
3834 /* Find what reg1 is equivalent to. Hopefully it will
3835 either be reg2 or reg2 plus a constant. */
3836 temp = loop_find_equiv_value (loop, reg1);
3838 if (find_common_reg_term (temp, reg2))
3839 initial_value = temp;
3842 /* Find what reg2 is equivalent to. Hopefully it will
3843 either be reg1 or reg1 plus a constant. Let's ignore
3844 the latter case for now since it is not so common. */
3845 temp = loop_find_equiv_value (loop, reg2);
3847 if (temp == loop_info->iteration_var)
3848 temp = initial_value;
3850 final_value = (const2 == const0_rtx)
3851 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3854 else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
3858 /* When running the loop optimizer twice, check_dbra_loop
3859 further obfuscates reversible loops of the form:
3860 for (i = init; i < init + const; i++). We often end up with
3861 final_value = 0, initial_value = temp, temp = temp2 - init,
3862 where temp2 = init + const. If the loop has a vtop we
3863 can replace initial_value with const. */
3865 temp = loop_find_equiv_value (loop, reg1);
3867 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3869 rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
3871 if (GET_CODE (temp2) == PLUS
3872 && XEXP (temp2, 0) == XEXP (temp, 1))
3873 initial_value = XEXP (temp2, 1);
3878 /* If have initial_value = reg + const1 and final_value = reg +
3879 const2, then replace initial_value with const1 and final_value
3880 with const2. This should be safe since we are protected by the
3881 initial comparison before entering the loop if we have a vtop.
3882 For example, a + b < a + c is not equivalent to b < c for all a
3883 when using modulo arithmetic.
3885 ??? Without a vtop we could still perform the optimization if we check
3886 the initial and final values carefully. */
3888 && (reg_term = find_common_reg_term (initial_value, final_value)))
3890 initial_value = subtract_reg_term (initial_value, reg_term);
3891 final_value = subtract_reg_term (final_value, reg_term);
3894 loop_info->initial_equiv_value = initial_value;
3895 loop_info->final_equiv_value = final_value;
3897 /* For EQ comparison loops, we don't have a valid final value.
3898 Check this now so that we won't leave an invalid value if we
3899 return early for any other reason. */
3900 if (comparison_code == EQ)
3901 loop_info->final_equiv_value = loop_info->final_value = 0;
3905 if (loop_dump_stream)
3906 fprintf (loop_dump_stream,
3907 "Loop iterations: Increment value can't be calculated.\n");
3911 if (GET_CODE (increment) != CONST_INT)
3913 /* If we have a REG, check to see if REG holds a constant value. */
3914 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3915 clear if it is worthwhile to try to handle such RTL. */
3916 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3917 increment = loop_find_equiv_value (loop, increment);
3919 if (GET_CODE (increment) != CONST_INT)
3921 if (loop_dump_stream)
3923 fprintf (loop_dump_stream,
3924 "Loop iterations: Increment value not constant ");
3925 print_rtl (loop_dump_stream, increment);
3926 fprintf (loop_dump_stream, ".\n");
3930 loop_info->increment = increment;
3933 if (GET_CODE (initial_value) != CONST_INT)
3935 if (loop_dump_stream)
3937 fprintf (loop_dump_stream,
3938 "Loop iterations: Initial value not constant ");
3939 print_rtl (loop_dump_stream, initial_value);
3940 fprintf (loop_dump_stream, ".\n");
3944 else if (comparison_code == EQ)
3946 if (loop_dump_stream)
3947 fprintf (loop_dump_stream,
3948 "Loop iterations: EQ comparison loop.\n");
3951 else if (GET_CODE (final_value) != CONST_INT)
3953 if (loop_dump_stream)
3955 fprintf (loop_dump_stream,
3956 "Loop iterations: Final value not constant ");
3957 print_rtl (loop_dump_stream, final_value);
3958 fprintf (loop_dump_stream, ".\n");
3963 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3966 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3967 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3968 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3969 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3971 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3972 - (INTVAL (final_value) < INTVAL (initial_value));
3974 if (INTVAL (increment) > 0)
3976 else if (INTVAL (increment) == 0)
3981 /* There are 27 different cases: compare_dir = -1, 0, 1;
3982 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3983 There are 4 normal cases, 4 reverse cases (where the iteration variable
3984 will overflow before the loop exits), 4 infinite loop cases, and 15
3985 immediate exit (0 or 1 iteration depending on loop type) cases.
3986 Only try to optimize the normal cases. */
3988 /* (compare_dir/final_larger/increment_dir)
3989 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3990 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3991 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3992 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3994 /* ?? If the meaning of reverse loops (where the iteration variable
3995 will overflow before the loop exits) is undefined, then could
3996 eliminate all of these special checks, and just always assume
3997 the loops are normal/immediate/infinite. Note that this means
3998 the sign of increment_dir does not have to be known. Also,
3999 since it does not really hurt if immediate exit loops or infinite loops
4000 are optimized, then that case could be ignored also, and hence all
4001 loops can be optimized.
4003 According to ANSI Spec, the reverse loop case result is undefined,
4004 because the action on overflow is undefined.
4006 See also the special test for NE loops below. */
4008 if (final_larger == increment_dir && final_larger != 0
4009 && (final_larger == compare_dir || compare_dir == 0))
4014 if (loop_dump_stream)
4015 fprintf (loop_dump_stream,
4016 "Loop iterations: Not normal loop.\n");
4020 /* Calculate the number of iterations, final_value is only an approximation,
4021 so correct for that. Note that abs_diff and n_iterations are
4022 unsigned, because they can be as large as 2^n - 1. */
4024 abs_inc = INTVAL (increment);
4026 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
4027 else if (abs_inc < 0)
4029 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
4035 /* For NE tests, make sure that the iteration variable won't miss
4036 the final value. If abs_diff mod abs_incr is not zero, then the
4037 iteration variable will overflow before the loop exits, and we
4038 can not calculate the number of iterations. */
4039 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4042 /* Note that the number of iterations could be calculated using
4043 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4044 handle potential overflow of the summation. */
4045 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4046 return loop_info->n_iterations;
4050 /* Replace uses of split bivs with their split pseudo register. This is
4051 for original instructions which remain after loop unrolling without
4055 remap_split_bivs (loop, x)
4059 struct loop_ivs *ivs = LOOP_IVS (loop);
4060 register enum rtx_code code;
4062 register const char *fmt;
4067 code = GET_CODE (x);
4082 /* If non-reduced/final-value givs were split, then this would also
4083 have to remap those givs also. */
4085 if (REGNO (x) < max_reg_before_loop
4086 && REG_IV_TYPE (ivs, REGNO (x)) == BASIC_INDUCT)
4087 return ivs->reg_biv_class[REGNO (x)]->biv->src_reg;
4094 fmt = GET_RTX_FORMAT (code);
4095 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4098 XEXP (x, i) = remap_split_bivs (loop, XEXP (x, i));
4099 else if (fmt[i] == 'E')
4102 for (j = 0; j < XVECLEN (x, i); j++)
4103 XVECEXP (x, i, j) = remap_split_bivs (loop, XVECEXP (x, i, j));
4109 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4110 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4111 return 0. COPY_START is where we can start looking for the insns
4112 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4115 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4116 must dominate LAST_UID.
4118 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4119 may not dominate LAST_UID.
4121 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4122 must dominate LAST_UID. */
4125 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4132 int passed_jump = 0;
4133 rtx p = NEXT_INSN (copy_start);
4135 while (INSN_UID (p) != first_uid)
4137 if (GET_CODE (p) == JUMP_INSN)
4139 /* Could not find FIRST_UID. */
4145 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4146 if (! INSN_P (p) || ! dead_or_set_regno_p (p, regno))
4149 /* FIRST_UID is always executed. */
4150 if (passed_jump == 0)
4153 while (INSN_UID (p) != last_uid)
4155 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4156 can not be sure that FIRST_UID dominates LAST_UID. */
4157 if (GET_CODE (p) == CODE_LABEL)
4159 /* Could not find LAST_UID, but we reached the end of the loop, so
4161 else if (p == copy_end)
4166 /* FIRST_UID is always executed if LAST_UID is executed. */
4170 /* This routine is called when the number of iterations for the unrolled
4171 loop is one. The goal is to identify a loop that begins with an
4172 unconditional branch to the loop continuation note (or a label just after).
4173 In this case, the unconditional branch that starts the loop needs to be
4174 deleted so that we execute the single iteration. */
4176 ujump_to_loop_cont (loop_start, loop_cont)
4180 rtx x, label, label_ref;
4182 /* See if loop start, or the next insn is an unconditional jump. */
4183 loop_start = next_nonnote_insn (loop_start);
4185 x = pc_set (loop_start);
4189 label_ref = SET_SRC (x);
4193 /* Examine insn after loop continuation note. Return if not a label. */
4194 label = next_nonnote_insn (loop_cont);
4195 if (label == 0 || GET_CODE (label) != CODE_LABEL)
4198 /* Return the loop start if the branch label matches the code label. */
4199 if (CODE_LABEL_NUMBER (label) == CODE_LABEL_NUMBER (XEXP (label_ref,0)))