1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor { int factor, count; } factors[NUM_FACTORS]
144 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
148 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
154 #include "insn-config.h"
155 #include "integrate.h"
159 #include "function.h"
163 #include "hard-reg-set.h"
164 #include "basic-block.h"
166 /* This controls which loops are unrolled, and by how much we unroll
169 #ifndef MAX_UNROLLED_INSNS
170 #define MAX_UNROLLED_INSNS 100
173 /* Indexed by register number, if non-zero, then it contains a pointer
174 to a struct induction for a DEST_REG giv which has been combined with
175 one of more address givs. This is needed because whenever such a DEST_REG
176 giv is modified, we must modify the value of all split address givs
177 that were combined with this DEST_REG giv. */
179 static struct induction **addr_combined_regs;
181 /* Indexed by register number, if this is a splittable induction variable,
182 then this will hold the current value of the register, which depends on the
185 static rtx *splittable_regs;
187 /* Indexed by register number, if this is a splittable induction variable,
188 this indicates if it was made from a derived giv. */
189 static char *derived_regs;
191 /* Indexed by register number, if this is a splittable induction variable,
192 then this will hold the number of instructions in the loop that modify
193 the induction variable. Used to ensure that only the last insn modifying
194 a split iv will update the original iv of the dest. */
196 static int *splittable_regs_updates;
198 /* Forward declarations. */
200 static void init_reg_map PARAMS ((struct inline_remap *, int));
201 static rtx calculate_giv_inc PARAMS ((rtx, rtx, unsigned int));
202 static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
203 static void final_reg_note_copy PARAMS ((rtx, struct inline_remap *));
204 static void copy_loop_body PARAMS ((rtx, rtx, struct inline_remap *, rtx, int,
205 enum unroll_types, rtx, rtx, rtx, rtx));
206 static int find_splittable_regs PARAMS ((const struct loop *,
207 enum unroll_types, rtx, int));
208 static int find_splittable_givs PARAMS ((const struct loop *,
209 struct iv_class *, enum unroll_types,
211 static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
212 static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
213 static int verify_addresses PARAMS ((struct induction *, rtx, int));
214 static rtx remap_split_bivs PARAMS ((rtx));
215 static rtx find_common_reg_term PARAMS ((rtx, rtx));
216 static rtx subtract_reg_term PARAMS ((rtx, rtx));
217 static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
218 static rtx ujump_to_loop_cont PARAMS ((rtx, rtx));
220 /* Try to unroll one loop and split induction variables in the loop.
222 The loop is described by the arguments LOOP and INSN_COUNT.
223 END_INSERT_BEFORE indicates where insns should be added which need
224 to be executed when the loop falls through. STRENGTH_REDUCTION_P
225 indicates whether information generated in the strength reduction
228 This function is intended to be called from within `strength_reduce'
232 unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
235 rtx end_insert_before;
236 int strength_reduce_p;
240 unsigned HOST_WIDE_INT temp;
241 int unroll_number = 1;
242 rtx copy_start, copy_end;
243 rtx insn, sequence, pattern, tem;
244 int max_labelno, max_insnno;
246 struct inline_remap *map;
247 char *local_label = NULL;
249 unsigned int max_local_regnum;
250 unsigned int maxregnum;
254 int splitting_not_safe = 0;
255 enum unroll_types unroll_type = UNROLL_NAIVE;
256 int loop_preconditioned = 0;
258 /* This points to the last real insn in the loop, which should be either
259 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
262 rtx loop_start = loop->start;
263 rtx loop_end = loop->end;
264 struct loop_info *loop_info = LOOP_INFO (loop);
266 /* Don't bother unrolling huge loops. Since the minimum factor is
267 two, loops greater than one half of MAX_UNROLLED_INSNS will never
269 if (insn_count > MAX_UNROLLED_INSNS / 2)
271 if (loop_dump_stream)
272 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
276 /* When emitting debugger info, we can't unroll loops with unequal numbers
277 of block_beg and block_end notes, because that would unbalance the block
278 structure of the function. This can happen as a result of the
279 "if (foo) bar; else break;" optimization in jump.c. */
280 /* ??? Gcc has a general policy that -g is never supposed to change the code
281 that the compiler emits, so we must disable this optimization always,
282 even if debug info is not being output. This is rare, so this should
283 not be a significant performance problem. */
285 if (1 /* write_symbols != NO_DEBUG */)
287 int block_begins = 0;
290 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
292 if (GET_CODE (insn) == NOTE)
294 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
296 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
298 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
299 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
301 /* Note, would be nice to add code to unroll EH
302 regions, but until that time, we punt (don't
303 unroll). For the proper way of doing it, see
304 expand_inline_function. */
306 if (loop_dump_stream)
307 fprintf (loop_dump_stream,
308 "Unrolling failure: cannot unroll EH regions.\n");
314 if (block_begins != block_ends)
316 if (loop_dump_stream)
317 fprintf (loop_dump_stream,
318 "Unrolling failure: Unbalanced block notes.\n");
323 /* Determine type of unroll to perform. Depends on the number of iterations
324 and the size of the loop. */
326 /* If there is no strength reduce info, then set
327 loop_info->n_iterations to zero. This can happen if
328 strength_reduce can't find any bivs in the loop. A value of zero
329 indicates that the number of iterations could not be calculated. */
331 if (! strength_reduce_p)
332 loop_info->n_iterations = 0;
334 if (loop_dump_stream && loop_info->n_iterations > 0)
336 fputs ("Loop unrolling: ", loop_dump_stream);
337 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
338 loop_info->n_iterations);
339 fputs (" iterations.\n", loop_dump_stream);
342 /* Find and save a pointer to the last nonnote insn in the loop. */
344 last_loop_insn = prev_nonnote_insn (loop_end);
346 /* Calculate how many times to unroll the loop. Indicate whether or
347 not the loop is being completely unrolled. */
349 if (loop_info->n_iterations == 1)
351 /* Handle the case where the loop begins with an unconditional
352 jump to the loop condition. Make sure to delete the jump
353 insn, otherwise the loop body will never execute. */
355 rtx ujump = ujump_to_loop_cont (loop->start, loop->cont);
359 /* If number of iterations is exactly 1, then eliminate the compare and
360 branch at the end of the loop since they will never be taken.
361 Then return, since no other action is needed here. */
363 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
364 don't do anything. */
366 if (GET_CODE (last_loop_insn) == BARRIER)
368 /* Delete the jump insn. This will delete the barrier also. */
369 delete_insn (PREV_INSN (last_loop_insn));
371 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
374 rtx prev = PREV_INSN (last_loop_insn);
376 delete_insn (last_loop_insn);
378 /* The immediately preceding insn may be a compare which must be
380 if (sets_cc0_p (prev))
385 /* Remove the loop notes since this is no longer a loop. */
387 delete_insn (loop->vtop);
389 delete_insn (loop->cont);
391 delete_insn (loop_start);
393 delete_insn (loop_end);
397 else if (loop_info->n_iterations > 0
398 /* Avoid overflow in the next expression. */
399 && loop_info->n_iterations < MAX_UNROLLED_INSNS
400 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
402 unroll_number = loop_info->n_iterations;
403 unroll_type = UNROLL_COMPLETELY;
405 else if (loop_info->n_iterations > 0)
407 /* Try to factor the number of iterations. Don't bother with the
408 general case, only using 2, 3, 5, and 7 will get 75% of all
409 numbers theoretically, and almost all in practice. */
411 for (i = 0; i < NUM_FACTORS; i++)
412 factors[i].count = 0;
414 temp = loop_info->n_iterations;
415 for (i = NUM_FACTORS - 1; i >= 0; i--)
416 while (temp % factors[i].factor == 0)
419 temp = temp / factors[i].factor;
422 /* Start with the larger factors first so that we generally
423 get lots of unrolling. */
427 for (i = 3; i >= 0; i--)
428 while (factors[i].count--)
430 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
432 unroll_number *= factors[i].factor;
433 temp *= factors[i].factor;
439 /* If we couldn't find any factors, then unroll as in the normal
441 if (unroll_number == 1)
443 if (loop_dump_stream)
444 fprintf (loop_dump_stream,
445 "Loop unrolling: No factors found.\n");
448 unroll_type = UNROLL_MODULO;
452 /* Default case, calculate number of times to unroll loop based on its
454 if (unroll_type == UNROLL_NAIVE)
456 if (8 * insn_count < MAX_UNROLLED_INSNS)
458 else if (4 * insn_count < MAX_UNROLLED_INSNS)
464 /* Now we know how many times to unroll the loop. */
466 if (loop_dump_stream)
467 fprintf (loop_dump_stream,
468 "Unrolling loop %d times.\n", unroll_number);
471 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
473 /* Loops of these types can start with jump down to the exit condition
474 in rare circumstances.
476 Consider a pair of nested loops where the inner loop is part
477 of the exit code for the outer loop.
479 In this case jump.c will not duplicate the exit test for the outer
480 loop, so it will start with a jump to the exit code.
482 Then consider if the inner loop turns out to iterate once and
483 only once. We will end up deleting the jumps associated with
484 the inner loop. However, the loop notes are not removed from
485 the instruction stream.
487 And finally assume that we can compute the number of iterations
490 In this case unroll may want to unroll the outer loop even though
491 it starts with a jump to the outer loop's exit code.
493 We could try to optimize this case, but it hardly seems worth it.
494 Just return without unrolling the loop in such cases. */
497 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
498 insn = NEXT_INSN (insn);
499 if (GET_CODE (insn) == JUMP_INSN)
503 if (unroll_type == UNROLL_COMPLETELY)
505 /* Completely unrolling the loop: Delete the compare and branch at
506 the end (the last two instructions). This delete must done at the
507 very end of loop unrolling, to avoid problems with calls to
508 back_branch_in_range_p, which is called by find_splittable_regs.
509 All increments of splittable bivs/givs are changed to load constant
512 copy_start = loop_start;
514 /* Set insert_before to the instruction immediately after the JUMP_INSN
515 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
516 the loop will be correctly handled by copy_loop_body. */
517 insert_before = NEXT_INSN (last_loop_insn);
519 /* Set copy_end to the insn before the jump at the end of the loop. */
520 if (GET_CODE (last_loop_insn) == BARRIER)
521 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
522 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
524 copy_end = PREV_INSN (last_loop_insn);
526 /* The instruction immediately before the JUMP_INSN may be a compare
527 instruction which we do not want to copy. */
528 if (sets_cc0_p (PREV_INSN (copy_end)))
529 copy_end = PREV_INSN (copy_end);
534 /* We currently can't unroll a loop if it doesn't end with a
535 JUMP_INSN. There would need to be a mechanism that recognizes
536 this case, and then inserts a jump after each loop body, which
537 jumps to after the last loop body. */
538 if (loop_dump_stream)
539 fprintf (loop_dump_stream,
540 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
544 else if (unroll_type == UNROLL_MODULO)
546 /* Partially unrolling the loop: The compare and branch at the end
547 (the last two instructions) must remain. Don't copy the compare
548 and branch instructions at the end of the loop. Insert the unrolled
549 code immediately before the compare/branch at the end so that the
550 code will fall through to them as before. */
552 copy_start = loop_start;
554 /* Set insert_before to the jump insn at the end of the loop.
555 Set copy_end to before the jump insn at the end of the loop. */
556 if (GET_CODE (last_loop_insn) == BARRIER)
558 insert_before = PREV_INSN (last_loop_insn);
559 copy_end = PREV_INSN (insert_before);
561 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
563 insert_before = last_loop_insn;
565 /* The instruction immediately before the JUMP_INSN may be a compare
566 instruction which we do not want to copy or delete. */
567 if (sets_cc0_p (PREV_INSN (insert_before)))
568 insert_before = PREV_INSN (insert_before);
570 copy_end = PREV_INSN (insert_before);
574 /* We currently can't unroll a loop if it doesn't end with a
575 JUMP_INSN. There would need to be a mechanism that recognizes
576 this case, and then inserts a jump after each loop body, which
577 jumps to after the last loop body. */
578 if (loop_dump_stream)
579 fprintf (loop_dump_stream,
580 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
586 /* Normal case: Must copy the compare and branch instructions at the
589 if (GET_CODE (last_loop_insn) == BARRIER)
591 /* Loop ends with an unconditional jump and a barrier.
592 Handle this like above, don't copy jump and barrier.
593 This is not strictly necessary, but doing so prevents generating
594 unconditional jumps to an immediately following label.
596 This will be corrected below if the target of this jump is
597 not the start_label. */
599 insert_before = PREV_INSN (last_loop_insn);
600 copy_end = PREV_INSN (insert_before);
602 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
604 /* Set insert_before to immediately after the JUMP_INSN, so that
605 NOTEs at the end of the loop will be correctly handled by
607 insert_before = NEXT_INSN (last_loop_insn);
608 copy_end = last_loop_insn;
612 /* We currently can't unroll a loop if it doesn't end with a
613 JUMP_INSN. There would need to be a mechanism that recognizes
614 this case, and then inserts a jump after each loop body, which
615 jumps to after the last loop body. */
616 if (loop_dump_stream)
617 fprintf (loop_dump_stream,
618 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
622 /* If copying exit test branches because they can not be eliminated,
623 then must convert the fall through case of the branch to a jump past
624 the end of the loop. Create a label to emit after the loop and save
625 it for later use. Do not use the label after the loop, if any, since
626 it might be used by insns outside the loop, or there might be insns
627 added before it later by final_[bg]iv_value which must be after
628 the real exit label. */
629 exit_label = gen_label_rtx ();
632 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
633 insn = NEXT_INSN (insn);
635 if (GET_CODE (insn) == JUMP_INSN)
637 /* The loop starts with a jump down to the exit condition test.
638 Start copying the loop after the barrier following this
640 copy_start = NEXT_INSN (insn);
642 /* Splitting induction variables doesn't work when the loop is
643 entered via a jump to the bottom, because then we end up doing
644 a comparison against a new register for a split variable, but
645 we did not execute the set insn for the new register because
646 it was skipped over. */
647 splitting_not_safe = 1;
648 if (loop_dump_stream)
649 fprintf (loop_dump_stream,
650 "Splitting not safe, because loop not entered at top.\n");
653 copy_start = loop_start;
656 /* This should always be the first label in the loop. */
657 start_label = NEXT_INSN (copy_start);
658 /* There may be a line number note and/or a loop continue note here. */
659 while (GET_CODE (start_label) == NOTE)
660 start_label = NEXT_INSN (start_label);
661 if (GET_CODE (start_label) != CODE_LABEL)
663 /* This can happen as a result of jump threading. If the first insns in
664 the loop test the same condition as the loop's backward jump, or the
665 opposite condition, then the backward jump will be modified to point
666 to elsewhere, and the loop's start label is deleted.
668 This case currently can not be handled by the loop unrolling code. */
670 if (loop_dump_stream)
671 fprintf (loop_dump_stream,
672 "Unrolling failure: unknown insns between BEG note and loop label.\n");
675 if (LABEL_NAME (start_label))
677 /* The jump optimization pass must have combined the original start label
678 with a named label for a goto. We can't unroll this case because
679 jumps which go to the named label must be handled differently than
680 jumps to the loop start, and it is impossible to differentiate them
682 if (loop_dump_stream)
683 fprintf (loop_dump_stream,
684 "Unrolling failure: loop start label is gone\n");
688 if (unroll_type == UNROLL_NAIVE
689 && GET_CODE (last_loop_insn) == BARRIER
690 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
691 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
693 /* In this case, we must copy the jump and barrier, because they will
694 not be converted to jumps to an immediately following label. */
696 insert_before = NEXT_INSN (last_loop_insn);
697 copy_end = last_loop_insn;
700 if (unroll_type == UNROLL_NAIVE
701 && GET_CODE (last_loop_insn) == JUMP_INSN
702 && start_label != JUMP_LABEL (last_loop_insn))
704 /* ??? The loop ends with a conditional branch that does not branch back
705 to the loop start label. In this case, we must emit an unconditional
706 branch to the loop exit after emitting the final branch.
707 copy_loop_body does not have support for this currently, so we
708 give up. It doesn't seem worthwhile to unroll anyways since
709 unrolling would increase the number of branch instructions
711 if (loop_dump_stream)
712 fprintf (loop_dump_stream,
713 "Unrolling failure: final conditional branch not to loop start\n");
717 /* Allocate a translation table for the labels and insn numbers.
718 They will be filled in as we copy the insns in the loop. */
720 max_labelno = max_label_num ();
721 max_insnno = get_max_uid ();
723 /* Various paths through the unroll code may reach the "egress" label
724 without initializing fields within the map structure.
726 To be safe, we use xcalloc to zero the memory. */
727 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
729 /* Allocate the label map. */
733 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
735 local_label = (char *) xcalloc (max_labelno, sizeof (char));
738 /* Search the loop and mark all local labels, i.e. the ones which have to
739 be distinct labels when copied. For all labels which might be
740 non-local, set their label_map entries to point to themselves.
741 If they happen to be local their label_map entries will be overwritten
742 before the loop body is copied. The label_map entries for local labels
743 will be set to a different value each time the loop body is copied. */
745 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
749 if (GET_CODE (insn) == CODE_LABEL)
750 local_label[CODE_LABEL_NUMBER (insn)] = 1;
751 else if (GET_CODE (insn) == JUMP_INSN)
753 if (JUMP_LABEL (insn))
754 set_label_in_map (map,
755 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
757 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
758 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
760 rtx pat = PATTERN (insn);
761 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
762 int len = XVECLEN (pat, diff_vec_p);
765 for (i = 0; i < len; i++)
767 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
768 set_label_in_map (map,
769 CODE_LABEL_NUMBER (label),
774 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
775 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
779 /* Allocate space for the insn map. */
781 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
783 /* Set this to zero, to indicate that we are doing loop unrolling,
784 not function inlining. */
785 map->inline_target = 0;
787 /* The register and constant maps depend on the number of registers
788 present, so the final maps can't be created until after
789 find_splittable_regs is called. However, they are needed for
790 preconditioning, so we create temporary maps when preconditioning
793 /* The preconditioning code may allocate two new pseudo registers. */
794 maxregnum = max_reg_num ();
796 /* local_regno is only valid for regnos < max_local_regnum. */
797 max_local_regnum = maxregnum;
799 /* Allocate and zero out the splittable_regs and addr_combined_regs
800 arrays. These must be zeroed here because they will be used if
801 loop preconditioning is performed, and must be zero for that case.
803 It is safe to do this here, since the extra registers created by the
804 preconditioning code and find_splittable_regs will never be used
805 to access the splittable_regs[] and addr_combined_regs[] arrays. */
807 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
808 derived_regs = (char *) xcalloc (maxregnum, sizeof (char));
809 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
811 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
812 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
814 /* Mark all local registers, i.e. the ones which are referenced only
816 if (INSN_UID (copy_end) < max_uid_for_loop)
818 int copy_start_luid = INSN_LUID (copy_start);
819 int copy_end_luid = INSN_LUID (copy_end);
821 /* If a register is used in the jump insn, we must not duplicate it
822 since it will also be used outside the loop. */
823 if (GET_CODE (copy_end) == JUMP_INSN)
826 /* If we have a target that uses cc0, then we also must not duplicate
827 the insn that sets cc0 before the jump insn, if one is present. */
829 if (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
833 /* If copy_start points to the NOTE that starts the loop, then we must
834 use the next luid, because invariant pseudo-regs moved out of the loop
835 have their lifetimes modified to start here, but they are not safe
837 if (copy_start == loop_start)
840 /* If a pseudo's lifetime is entirely contained within this loop, then we
841 can use a different pseudo in each unrolled copy of the loop. This
842 results in better code. */
843 /* We must limit the generic test to max_reg_before_loop, because only
844 these pseudo registers have valid regno_first_uid info. */
845 for (r = FIRST_PSEUDO_REGISTER; r < max_reg_before_loop; ++r)
846 if (REGNO_FIRST_UID (r) > 0 && REGNO_FIRST_UID (r) <= max_uid_for_loop
847 && uid_luid[REGNO_FIRST_UID (r)] >= copy_start_luid
848 && REGNO_LAST_UID (r) > 0 && REGNO_LAST_UID (r) <= max_uid_for_loop
849 && uid_luid[REGNO_LAST_UID (r)] <= copy_end_luid)
851 /* However, we must also check for loop-carried dependencies.
852 If the value the pseudo has at the end of iteration X is
853 used by iteration X+1, then we can not use a different pseudo
854 for each unrolled copy of the loop. */
855 /* A pseudo is safe if regno_first_uid is a set, and this
856 set dominates all instructions from regno_first_uid to
858 /* ??? This check is simplistic. We would get better code if
859 this check was more sophisticated. */
860 if (set_dominates_use (r, REGNO_FIRST_UID (r), REGNO_LAST_UID (r),
861 copy_start, copy_end))
864 if (loop_dump_stream)
867 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
869 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
873 /* Givs that have been created from multiple biv increments always have
875 for (r = first_increment_giv; r <= last_increment_giv; r++)
878 if (loop_dump_stream)
879 fprintf (loop_dump_stream, "Marked reg %d as local\n", r);
883 /* If this loop requires exit tests when unrolled, check to see if we
884 can precondition the loop so as to make the exit tests unnecessary.
885 Just like variable splitting, this is not safe if the loop is entered
886 via a jump to the bottom. Also, can not do this if no strength
887 reduce info, because precondition_loop_p uses this info. */
889 /* Must copy the loop body for preconditioning before the following
890 find_splittable_regs call since that will emit insns which need to
891 be after the preconditioned loop copies, but immediately before the
892 unrolled loop copies. */
894 /* Also, it is not safe to split induction variables for the preconditioned
895 copies of the loop body. If we split induction variables, then the code
896 assumes that each induction variable can be represented as a function
897 of its initial value and the loop iteration number. This is not true
898 in this case, because the last preconditioned copy of the loop body
899 could be any iteration from the first up to the `unroll_number-1'th,
900 depending on the initial value of the iteration variable. Therefore
901 we can not split induction variables here, because we can not calculate
902 their value. Hence, this code must occur before find_splittable_regs
905 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
907 rtx initial_value, final_value, increment;
908 enum machine_mode mode;
910 if (precondition_loop_p (loop,
911 &initial_value, &final_value, &increment,
916 int abs_inc, neg_inc;
918 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
920 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
921 "unroll_loop_precondition");
922 global_const_equiv_varray = map->const_equiv_varray;
924 init_reg_map (map, maxregnum);
926 /* Limit loop unrolling to 4, since this will make 7 copies of
928 if (unroll_number > 4)
931 /* Save the absolute value of the increment, and also whether or
932 not it is negative. */
934 abs_inc = INTVAL (increment);
943 /* Calculate the difference between the final and initial values.
944 Final value may be a (plus (reg x) (const_int 1)) rtx.
945 Let the following cse pass simplify this if initial value is
948 We must copy the final and initial values here to avoid
949 improperly shared rtl. */
951 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
952 copy_rtx (initial_value), NULL_RTX, 0,
955 /* Now calculate (diff % (unroll * abs (increment))) by using an
957 diff = expand_binop (GET_MODE (diff), and_optab, diff,
958 GEN_INT (unroll_number * abs_inc - 1),
959 NULL_RTX, 0, OPTAB_LIB_WIDEN);
961 /* Now emit a sequence of branches to jump to the proper precond
964 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
965 for (i = 0; i < unroll_number; i++)
966 labels[i] = gen_label_rtx ();
968 /* Check for the case where the initial value is greater than or
969 equal to the final value. In that case, we want to execute
970 exactly one loop iteration. The code below will fail for this
971 case. This check does not apply if the loop has a NE
972 comparison at the end. */
974 if (loop_info->comparison_code != NE)
976 emit_cmp_and_jump_insns (initial_value, final_value,
978 NULL_RTX, mode, 0, 0, labels[1]);
979 JUMP_LABEL (get_last_insn ()) = labels[1];
980 LABEL_NUSES (labels[1])++;
983 /* Assuming the unroll_number is 4, and the increment is 2, then
984 for a negative increment: for a positive increment:
985 diff = 0,1 precond 0 diff = 0,7 precond 0
986 diff = 2,3 precond 3 diff = 1,2 precond 1
987 diff = 4,5 precond 2 diff = 3,4 precond 2
988 diff = 6,7 precond 1 diff = 5,6 precond 3 */
990 /* We only need to emit (unroll_number - 1) branches here, the
991 last case just falls through to the following code. */
993 /* ??? This would give better code if we emitted a tree of branches
994 instead of the current linear list of branches. */
996 for (i = 0; i < unroll_number - 1; i++)
999 enum rtx_code cmp_code;
1001 /* For negative increments, must invert the constant compared
1002 against, except when comparing against zero. */
1010 cmp_const = unroll_number - i;
1019 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
1020 cmp_code, NULL_RTX, mode, 0, 0,
1022 JUMP_LABEL (get_last_insn ()) = labels[i];
1023 LABEL_NUSES (labels[i])++;
1026 /* If the increment is greater than one, then we need another branch,
1027 to handle other cases equivalent to 0. */
1029 /* ??? This should be merged into the code above somehow to help
1030 simplify the code here, and reduce the number of branches emitted.
1031 For the negative increment case, the branch here could easily
1032 be merged with the `0' case branch above. For the positive
1033 increment case, it is not clear how this can be simplified. */
1038 enum rtx_code cmp_code;
1042 cmp_const = abs_inc - 1;
1047 cmp_const = abs_inc * (unroll_number - 1) + 1;
1051 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1052 NULL_RTX, mode, 0, 0, labels[0]);
1053 JUMP_LABEL (get_last_insn ()) = labels[0];
1054 LABEL_NUSES (labels[0])++;
1057 sequence = gen_sequence ();
1059 emit_insn_before (sequence, loop_start);
1061 /* Only the last copy of the loop body here needs the exit
1062 test, so set copy_end to exclude the compare/branch here,
1063 and then reset it inside the loop when get to the last
1066 if (GET_CODE (last_loop_insn) == BARRIER)
1067 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1068 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1070 copy_end = PREV_INSN (last_loop_insn);
1072 /* The immediately preceding insn may be a compare which we do not
1074 if (sets_cc0_p (PREV_INSN (copy_end)))
1075 copy_end = PREV_INSN (copy_end);
1081 for (i = 1; i < unroll_number; i++)
1083 emit_label_after (labels[unroll_number - i],
1084 PREV_INSN (loop_start));
1086 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1087 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1088 (VARRAY_SIZE (map->const_equiv_varray)
1089 * sizeof (struct const_equiv_data)));
1092 for (j = 0; j < max_labelno; j++)
1094 set_label_in_map (map, j, gen_label_rtx ());
1096 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1100 = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1101 record_base_value (REGNO (map->reg_map[r]),
1102 regno_reg_rtx[r], 0);
1104 /* The last copy needs the compare/branch insns at the end,
1105 so reset copy_end here if the loop ends with a conditional
1108 if (i == unroll_number - 1)
1110 if (GET_CODE (last_loop_insn) == BARRIER)
1111 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1113 copy_end = last_loop_insn;
1116 /* None of the copies are the `last_iteration', so just
1117 pass zero for that parameter. */
1118 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1119 unroll_type, start_label, loop_end,
1120 loop_start, copy_end);
1122 emit_label_after (labels[0], PREV_INSN (loop_start));
1124 if (GET_CODE (last_loop_insn) == BARRIER)
1126 insert_before = PREV_INSN (last_loop_insn);
1127 copy_end = PREV_INSN (insert_before);
1131 insert_before = last_loop_insn;
1133 /* The instruction immediately before the JUMP_INSN may be a compare
1134 instruction which we do not want to copy or delete. */
1135 if (sets_cc0_p (PREV_INSN (insert_before)))
1136 insert_before = PREV_INSN (insert_before);
1138 copy_end = PREV_INSN (insert_before);
1141 /* Set unroll type to MODULO now. */
1142 unroll_type = UNROLL_MODULO;
1143 loop_preconditioned = 1;
1150 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1151 the loop unless all loops are being unrolled. */
1152 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1154 if (loop_dump_stream)
1155 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1159 /* At this point, we are guaranteed to unroll the loop. */
1161 /* Keep track of the unroll factor for the loop. */
1162 loop_info->unroll_number = unroll_number;
1164 /* For each biv and giv, determine whether it can be safely split into
1165 a different variable for each unrolled copy of the loop body.
1166 We precalculate and save this info here, since computing it is
1169 Do this before deleting any instructions from the loop, so that
1170 back_branch_in_range_p will work correctly. */
1172 if (splitting_not_safe)
1175 temp = find_splittable_regs (loop, unroll_type,
1176 end_insert_before, unroll_number);
1178 /* find_splittable_regs may have created some new registers, so must
1179 reallocate the reg_map with the new larger size, and must realloc
1180 the constant maps also. */
1182 maxregnum = max_reg_num ();
1183 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1185 init_reg_map (map, maxregnum);
1187 if (map->const_equiv_varray == 0)
1188 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1189 maxregnum + temp * unroll_number * 2,
1191 global_const_equiv_varray = map->const_equiv_varray;
1193 /* Search the list of bivs and givs to find ones which need to be remapped
1194 when split, and set their reg_map entry appropriately. */
1196 for (bl = loop_iv_list; bl; bl = bl->next)
1198 if (REGNO (bl->biv->src_reg) != bl->regno)
1199 map->reg_map[bl->regno] = bl->biv->src_reg;
1201 /* Currently, non-reduced/final-value givs are never split. */
1202 for (v = bl->giv; v; v = v->next_iv)
1203 if (REGNO (v->src_reg) != bl->regno)
1204 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1208 /* Use our current register alignment and pointer flags. */
1209 map->regno_pointer_flag = cfun->emit->regno_pointer_flag;
1210 map->regno_pointer_align = cfun->emit->regno_pointer_align;
1212 /* If the loop is being partially unrolled, and the iteration variables
1213 are being split, and are being renamed for the split, then must fix up
1214 the compare/jump instruction at the end of the loop to refer to the new
1215 registers. This compare isn't copied, so the registers used in it
1216 will never be replaced if it isn't done here. */
1218 if (unroll_type == UNROLL_MODULO)
1220 insn = NEXT_INSN (copy_end);
1221 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1222 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1225 /* For unroll_number times, make a copy of each instruction
1226 between copy_start and copy_end, and insert these new instructions
1227 before the end of the loop. */
1229 for (i = 0; i < unroll_number; i++)
1231 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1232 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1233 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1236 for (j = 0; j < max_labelno; j++)
1238 set_label_in_map (map, j, gen_label_rtx ());
1240 for (r = FIRST_PSEUDO_REGISTER; r < max_local_regnum; r++)
1243 map->reg_map[r] = gen_reg_rtx (GET_MODE (regno_reg_rtx[r]));
1244 record_base_value (REGNO (map->reg_map[r]),
1245 regno_reg_rtx[r], 0);
1248 /* If loop starts with a branch to the test, then fix it so that
1249 it points to the test of the first unrolled copy of the loop. */
1250 if (i == 0 && loop_start != copy_start)
1252 insn = PREV_INSN (copy_start);
1253 pattern = PATTERN (insn);
1255 tem = get_label_from_map (map,
1257 (XEXP (SET_SRC (pattern), 0)));
1258 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1260 /* Set the jump label so that it can be used by later loop unrolling
1262 JUMP_LABEL (insn) = tem;
1263 LABEL_NUSES (tem)++;
1266 copy_loop_body (copy_start, copy_end, map, exit_label,
1267 i == unroll_number - 1, unroll_type, start_label,
1268 loop_end, insert_before, insert_before);
1271 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1272 insn to be deleted. This prevents any runaway delete_insn call from
1273 more insns that it should, as it always stops at a CODE_LABEL. */
1275 /* Delete the compare and branch at the end of the loop if completely
1276 unrolling the loop. Deleting the backward branch at the end also
1277 deletes the code label at the start of the loop. This is done at
1278 the very end to avoid problems with back_branch_in_range_p. */
1280 if (unroll_type == UNROLL_COMPLETELY)
1281 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1283 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1285 /* Delete all of the original loop instructions. Don't delete the
1286 LOOP_BEG note, or the first code label in the loop. */
1288 insn = NEXT_INSN (copy_start);
1289 while (insn != safety_label)
1291 /* ??? Don't delete named code labels. They will be deleted when the
1292 jump that references them is deleted. Otherwise, we end up deleting
1293 them twice, which causes them to completely disappear instead of turn
1294 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1295 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1296 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1297 associated LABEL_DECL to point to one of the new label instances. */
1298 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1299 if (insn != start_label
1300 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1301 && ! (GET_CODE (insn) == NOTE
1302 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1303 insn = delete_insn (insn);
1305 insn = NEXT_INSN (insn);
1308 /* Can now delete the 'safety' label emitted to protect us from runaway
1309 delete_insn calls. */
1310 if (INSN_DELETED_P (safety_label))
1312 delete_insn (safety_label);
1314 /* If exit_label exists, emit it after the loop. Doing the emit here
1315 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1316 This is needed so that mostly_true_jump in reorg.c will treat jumps
1317 to this loop end label correctly, i.e. predict that they are usually
1320 emit_label_after (exit_label, loop_end);
1323 if (unroll_type == UNROLL_COMPLETELY)
1325 /* Remove the loop notes since this is no longer a loop. */
1327 delete_insn (loop->vtop);
1329 delete_insn (loop->cont);
1331 delete_insn (loop_start);
1333 delete_insn (loop_end);
1336 if (map->const_equiv_varray)
1337 VARRAY_FREE (map->const_equiv_varray);
1340 free (map->label_map);
1343 free (map->insn_map);
1344 free (splittable_regs);
1345 free (derived_regs);
1346 free (splittable_regs_updates);
1347 free (addr_combined_regs);
1350 free (map->reg_map);
1354 /* Return true if the loop can be safely, and profitably, preconditioned
1355 so that the unrolled copies of the loop body don't need exit tests.
1357 This only works if final_value, initial_value and increment can be
1358 determined, and if increment is a constant power of 2.
1359 If increment is not a power of 2, then the preconditioning modulo
1360 operation would require a real modulo instead of a boolean AND, and this
1361 is not considered `profitable'. */
1363 /* ??? If the loop is known to be executed very many times, or the machine
1364 has a very cheap divide instruction, then preconditioning is a win even
1365 when the increment is not a power of 2. Use RTX_COST to compute
1366 whether divide is cheap.
1367 ??? A divide by constant doesn't actually need a divide, look at
1368 expand_divmod. The reduced cost of this optimized modulo is not
1369 reflected in RTX_COST. */
1372 precondition_loop_p (loop, initial_value, final_value, increment, mode)
1373 const struct loop *loop;
1374 rtx *initial_value, *final_value, *increment;
1375 enum machine_mode *mode;
1377 rtx loop_start = loop->start;
1378 struct loop_info *loop_info = LOOP_INFO (loop);
1380 if (loop_info->n_iterations > 0)
1382 *initial_value = const0_rtx;
1383 *increment = const1_rtx;
1384 *final_value = GEN_INT (loop_info->n_iterations);
1387 if (loop_dump_stream)
1389 fputs ("Preconditioning: Success, number of iterations known, ",
1391 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1392 loop_info->n_iterations);
1393 fputs (".\n", loop_dump_stream);
1398 if (loop_info->initial_value == 0)
1400 if (loop_dump_stream)
1401 fprintf (loop_dump_stream,
1402 "Preconditioning: Could not find initial value.\n");
1405 else if (loop_info->increment == 0)
1407 if (loop_dump_stream)
1408 fprintf (loop_dump_stream,
1409 "Preconditioning: Could not find increment value.\n");
1412 else if (GET_CODE (loop_info->increment) != CONST_INT)
1414 if (loop_dump_stream)
1415 fprintf (loop_dump_stream,
1416 "Preconditioning: Increment not a constant.\n");
1419 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1420 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1422 if (loop_dump_stream)
1423 fprintf (loop_dump_stream,
1424 "Preconditioning: Increment not a constant power of 2.\n");
1428 /* Unsigned_compare and compare_dir can be ignored here, since they do
1429 not matter for preconditioning. */
1431 if (loop_info->final_value == 0)
1433 if (loop_dump_stream)
1434 fprintf (loop_dump_stream,
1435 "Preconditioning: EQ comparison loop.\n");
1439 /* Must ensure that final_value is invariant, so call
1440 loop_invariant_p to check. Before doing so, must check regno
1441 against max_reg_before_loop to make sure that the register is in
1442 the range covered by loop_invariant_p. If it isn't, then it is
1443 most likely a biv/giv which by definition are not invariant. */
1444 if ((GET_CODE (loop_info->final_value) == REG
1445 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1446 || (GET_CODE (loop_info->final_value) == PLUS
1447 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1448 || ! loop_invariant_p (loop, loop_info->final_value))
1450 if (loop_dump_stream)
1451 fprintf (loop_dump_stream,
1452 "Preconditioning: Final value not invariant.\n");
1456 /* Fail for floating point values, since the caller of this function
1457 does not have code to deal with them. */
1458 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1459 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1461 if (loop_dump_stream)
1462 fprintf (loop_dump_stream,
1463 "Preconditioning: Floating point final or initial value.\n");
1467 /* Fail if loop_info->iteration_var is not live before loop_start,
1468 since we need to test its value in the preconditioning code. */
1470 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1471 > INSN_LUID (loop_start))
1473 if (loop_dump_stream)
1474 fprintf (loop_dump_stream,
1475 "Preconditioning: Iteration var not live before loop start.\n");
1479 /* Note that loop_iterations biases the initial value for GIV iterators
1480 such as "while (i-- > 0)" so that we can calculate the number of
1481 iterations just like for BIV iterators.
1483 Also note that the absolute values of initial_value and
1484 final_value are unimportant as only their difference is used for
1485 calculating the number of loop iterations. */
1486 *initial_value = loop_info->initial_value;
1487 *increment = loop_info->increment;
1488 *final_value = loop_info->final_value;
1490 /* Decide what mode to do these calculations in. Choose the larger
1491 of final_value's mode and initial_value's mode, or a full-word if
1492 both are constants. */
1493 *mode = GET_MODE (*final_value);
1494 if (*mode == VOIDmode)
1496 *mode = GET_MODE (*initial_value);
1497 if (*mode == VOIDmode)
1500 else if (*mode != GET_MODE (*initial_value)
1501 && (GET_MODE_SIZE (*mode)
1502 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1503 *mode = GET_MODE (*initial_value);
1506 if (loop_dump_stream)
1507 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1512 /* All pseudo-registers must be mapped to themselves. Two hard registers
1513 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1514 REGNUM, to avoid function-inlining specific conversions of these
1515 registers. All other hard regs can not be mapped because they may be
1520 init_reg_map (map, maxregnum)
1521 struct inline_remap *map;
1526 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1527 map->reg_map[i] = regno_reg_rtx[i];
1528 /* Just clear the rest of the entries. */
1529 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1530 map->reg_map[i] = 0;
1532 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1533 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1534 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1535 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1538 /* Strength-reduction will often emit code for optimized biv/givs which
1539 calculates their value in a temporary register, and then copies the result
1540 to the iv. This procedure reconstructs the pattern computing the iv;
1541 verifying that all operands are of the proper form.
1543 PATTERN must be the result of single_set.
1544 The return value is the amount that the giv is incremented by. */
1547 calculate_giv_inc (pattern, src_insn, regno)
1548 rtx pattern, src_insn;
1552 rtx increment_total = 0;
1556 /* Verify that we have an increment insn here. First check for a plus
1557 as the set source. */
1558 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1560 /* SR sometimes computes the new giv value in a temp, then copies it
1562 src_insn = PREV_INSN (src_insn);
1563 pattern = PATTERN (src_insn);
1564 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1567 /* The last insn emitted is not needed, so delete it to avoid confusing
1568 the second cse pass. This insn sets the giv unnecessarily. */
1569 delete_insn (get_last_insn ());
1572 /* Verify that we have a constant as the second operand of the plus. */
1573 increment = XEXP (SET_SRC (pattern), 1);
1574 if (GET_CODE (increment) != CONST_INT)
1576 /* SR sometimes puts the constant in a register, especially if it is
1577 too big to be an add immed operand. */
1578 src_insn = PREV_INSN (src_insn);
1579 increment = SET_SRC (PATTERN (src_insn));
1581 /* SR may have used LO_SUM to compute the constant if it is too large
1582 for a load immed operand. In this case, the constant is in operand
1583 one of the LO_SUM rtx. */
1584 if (GET_CODE (increment) == LO_SUM)
1585 increment = XEXP (increment, 1);
1587 /* Some ports store large constants in memory and add a REG_EQUAL
1588 note to the store insn. */
1589 else if (GET_CODE (increment) == MEM)
1591 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1593 increment = XEXP (note, 0);
1596 else if (GET_CODE (increment) == IOR
1597 || GET_CODE (increment) == ASHIFT
1598 || GET_CODE (increment) == PLUS)
1600 /* The rs6000 port loads some constants with IOR.
1601 The alpha port loads some constants with ASHIFT and PLUS. */
1602 rtx second_part = XEXP (increment, 1);
1603 enum rtx_code code = GET_CODE (increment);
1605 src_insn = PREV_INSN (src_insn);
1606 increment = SET_SRC (PATTERN (src_insn));
1607 /* Don't need the last insn anymore. */
1608 delete_insn (get_last_insn ());
1610 if (GET_CODE (second_part) != CONST_INT
1611 || GET_CODE (increment) != CONST_INT)
1615 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1616 else if (code == PLUS)
1617 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1619 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1622 if (GET_CODE (increment) != CONST_INT)
1625 /* The insn loading the constant into a register is no longer needed,
1627 delete_insn (get_last_insn ());
1630 if (increment_total)
1631 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1633 increment_total = increment;
1635 /* Check that the source register is the same as the register we expected
1636 to see as the source. If not, something is seriously wrong. */
1637 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1638 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1640 /* Some machines (e.g. the romp), may emit two add instructions for
1641 certain constants, so lets try looking for another add immediately
1642 before this one if we have only seen one add insn so far. */
1648 src_insn = PREV_INSN (src_insn);
1649 pattern = PATTERN (src_insn);
1651 delete_insn (get_last_insn ());
1659 return increment_total;
1662 /* Copy REG_NOTES, except for insn references, because not all insn_map
1663 entries are valid yet. We do need to copy registers now though, because
1664 the reg_map entries can change during copying. */
1667 initial_reg_note_copy (notes, map)
1669 struct inline_remap *map;
1676 copy = rtx_alloc (GET_CODE (notes));
1677 PUT_MODE (copy, GET_MODE (notes));
1679 if (GET_CODE (notes) == EXPR_LIST)
1680 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1681 else if (GET_CODE (notes) == INSN_LIST)
1682 /* Don't substitute for these yet. */
1683 XEXP (copy, 0) = XEXP (notes, 0);
1687 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1692 /* Fixup insn references in copied REG_NOTES. */
1695 final_reg_note_copy (notes, map)
1697 struct inline_remap *map;
1701 for (note = notes; note; note = XEXP (note, 1))
1702 if (GET_CODE (note) == INSN_LIST)
1703 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1706 /* Copy each instruction in the loop, substituting from map as appropriate.
1707 This is very similar to a loop in expand_inline_function. */
1710 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1711 unroll_type, start_label, loop_end, insert_before,
1713 rtx copy_start, copy_end;
1714 struct inline_remap *map;
1717 enum unroll_types unroll_type;
1718 rtx start_label, loop_end, insert_before, copy_notes_from;
1721 rtx set, tem, copy = NULL_RTX;
1722 int dest_reg_was_split, i;
1726 rtx final_label = 0;
1727 rtx giv_inc, giv_dest_reg, giv_src_reg;
1729 /* If this isn't the last iteration, then map any references to the
1730 start_label to final_label. Final label will then be emitted immediately
1731 after the end of this loop body if it was ever used.
1733 If this is the last iteration, then map references to the start_label
1735 if (! last_iteration)
1737 final_label = gen_label_rtx ();
1738 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1742 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1746 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1747 Else gen_sequence could return a raw pattern for a jump which we pass
1748 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1749 a variety of losing behaviors later. */
1750 emit_note (0, NOTE_INSN_DELETED);
1755 insn = NEXT_INSN (insn);
1757 map->orig_asm_operands_vector = 0;
1759 switch (GET_CODE (insn))
1762 pattern = PATTERN (insn);
1766 /* Check to see if this is a giv that has been combined with
1767 some split address givs. (Combined in the sense that
1768 `combine_givs' in loop.c has put two givs in the same register.)
1769 In this case, we must search all givs based on the same biv to
1770 find the address givs. Then split the address givs.
1771 Do this before splitting the giv, since that may map the
1772 SET_DEST to a new register. */
1774 if ((set = single_set (insn))
1775 && GET_CODE (SET_DEST (set)) == REG
1776 && addr_combined_regs[REGNO (SET_DEST (set))])
1778 struct iv_class *bl;
1779 struct induction *v, *tv;
1780 unsigned int regno = REGNO (SET_DEST (set));
1782 v = addr_combined_regs[REGNO (SET_DEST (set))];
1783 bl = reg_biv_class[REGNO (v->src_reg)];
1785 /* Although the giv_inc amount is not needed here, we must call
1786 calculate_giv_inc here since it might try to delete the
1787 last insn emitted. If we wait until later to call it,
1788 we might accidentally delete insns generated immediately
1789 below by emit_unrolled_add. */
1791 if (! derived_regs[regno])
1792 giv_inc = calculate_giv_inc (set, insn, regno);
1794 /* Now find all address giv's that were combined with this
1796 for (tv = bl->giv; tv; tv = tv->next_iv)
1797 if (tv->giv_type == DEST_ADDR && tv->same == v)
1801 /* If this DEST_ADDR giv was not split, then ignore it. */
1802 if (*tv->location != tv->dest_reg)
1805 /* Scale this_giv_inc if the multiplicative factors of
1806 the two givs are different. */
1807 this_giv_inc = INTVAL (giv_inc);
1808 if (tv->mult_val != v->mult_val)
1809 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1810 * INTVAL (tv->mult_val));
1812 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1813 *tv->location = tv->dest_reg;
1815 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1817 /* Must emit an insn to increment the split address
1818 giv. Add in the const_adjust field in case there
1819 was a constant eliminated from the address. */
1820 rtx value, dest_reg;
1822 /* tv->dest_reg will be either a bare register,
1823 or else a register plus a constant. */
1824 if (GET_CODE (tv->dest_reg) == REG)
1825 dest_reg = tv->dest_reg;
1827 dest_reg = XEXP (tv->dest_reg, 0);
1829 /* Check for shared address givs, and avoid
1830 incrementing the shared pseudo reg more than
1832 if (! tv->same_insn && ! tv->shared)
1834 /* tv->dest_reg may actually be a (PLUS (REG)
1835 (CONST)) here, so we must call plus_constant
1836 to add the const_adjust amount before calling
1837 emit_unrolled_add below. */
1838 value = plus_constant (tv->dest_reg,
1841 if (GET_CODE (value) == PLUS)
1843 /* The constant could be too large for an add
1844 immediate, so can't directly emit an insn
1846 emit_unrolled_add (dest_reg, XEXP (value, 0),
1851 /* Reset the giv to be just the register again, in case
1852 it is used after the set we have just emitted.
1853 We must subtract the const_adjust factor added in
1855 tv->dest_reg = plus_constant (dest_reg,
1856 - tv->const_adjust);
1857 *tv->location = tv->dest_reg;
1862 /* If this is a setting of a splittable variable, then determine
1863 how to split the variable, create a new set based on this split,
1864 and set up the reg_map so that later uses of the variable will
1865 use the new split variable. */
1867 dest_reg_was_split = 0;
1869 if ((set = single_set (insn))
1870 && GET_CODE (SET_DEST (set)) == REG
1871 && splittable_regs[REGNO (SET_DEST (set))])
1873 unsigned int regno = REGNO (SET_DEST (set));
1874 unsigned int src_regno;
1876 dest_reg_was_split = 1;
1878 giv_dest_reg = SET_DEST (set);
1879 if (derived_regs[regno])
1881 /* ??? This relies on SET_SRC (SET) to be of
1882 the form (plus (reg) (const_int)), and thus
1883 forces recombine_givs to restrict the kind
1884 of giv derivations it does before unrolling. */
1885 giv_src_reg = XEXP (SET_SRC (set), 0);
1886 giv_inc = XEXP (SET_SRC (set), 1);
1890 giv_src_reg = giv_dest_reg;
1891 /* Compute the increment value for the giv, if it wasn't
1892 already computed above. */
1894 giv_inc = calculate_giv_inc (set, insn, regno);
1896 src_regno = REGNO (giv_src_reg);
1898 if (unroll_type == UNROLL_COMPLETELY)
1900 /* Completely unrolling the loop. Set the induction
1901 variable to a known constant value. */
1903 /* The value in splittable_regs may be an invariant
1904 value, so we must use plus_constant here. */
1905 splittable_regs[regno]
1906 = plus_constant (splittable_regs[src_regno],
1909 if (GET_CODE (splittable_regs[regno]) == PLUS)
1911 giv_src_reg = XEXP (splittable_regs[regno], 0);
1912 giv_inc = XEXP (splittable_regs[regno], 1);
1916 /* The splittable_regs value must be a REG or a
1917 CONST_INT, so put the entire value in the giv_src_reg
1919 giv_src_reg = splittable_regs[regno];
1920 giv_inc = const0_rtx;
1925 /* Partially unrolling loop. Create a new pseudo
1926 register for the iteration variable, and set it to
1927 be a constant plus the original register. Except
1928 on the last iteration, when the result has to
1929 go back into the original iteration var register. */
1931 /* Handle bivs which must be mapped to a new register
1932 when split. This happens for bivs which need their
1933 final value set before loop entry. The new register
1934 for the biv was stored in the biv's first struct
1935 induction entry by find_splittable_regs. */
1937 if (regno < max_reg_before_loop
1938 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1940 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1941 giv_dest_reg = giv_src_reg;
1945 /* If non-reduced/final-value givs were split, then
1946 this would have to remap those givs also. See
1947 find_splittable_regs. */
1950 splittable_regs[regno]
1951 = simplify_gen_binary (PLUS, GET_MODE (giv_src_reg),
1953 splittable_regs[src_regno]);
1954 giv_inc = splittable_regs[regno];
1956 /* Now split the induction variable by changing the dest
1957 of this insn to a new register, and setting its
1958 reg_map entry to point to this new register.
1960 If this is the last iteration, and this is the last insn
1961 that will update the iv, then reuse the original dest,
1962 to ensure that the iv will have the proper value when
1963 the loop exits or repeats.
1965 Using splittable_regs_updates here like this is safe,
1966 because it can only be greater than one if all
1967 instructions modifying the iv are always executed in
1970 if (! last_iteration
1971 || (splittable_regs_updates[regno]-- != 1))
1973 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1975 map->reg_map[regno] = tem;
1976 record_base_value (REGNO (tem),
1977 giv_inc == const0_rtx
1979 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1980 giv_src_reg, giv_inc),
1984 map->reg_map[regno] = giv_src_reg;
1987 /* The constant being added could be too large for an add
1988 immediate, so can't directly emit an insn here. */
1989 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1990 copy = get_last_insn ();
1991 pattern = PATTERN (copy);
1995 pattern = copy_rtx_and_substitute (pattern, map, 0);
1996 copy = emit_insn (pattern);
1998 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2001 /* If this insn is setting CC0, it may need to look at
2002 the insn that uses CC0 to see what type of insn it is.
2003 In that case, the call to recog via validate_change will
2004 fail. So don't substitute constants here. Instead,
2005 do it when we emit the following insn.
2007 For example, see the pyr.md file. That machine has signed and
2008 unsigned compares. The compare patterns must check the
2009 following branch insn to see which what kind of compare to
2012 If the previous insn set CC0, substitute constants on it as
2014 if (sets_cc0_p (PATTERN (copy)) != 0)
2019 try_constants (cc0_insn, map);
2021 try_constants (copy, map);
2024 try_constants (copy, map);
2027 /* Make split induction variable constants `permanent' since we
2028 know there are no backward branches across iteration variable
2029 settings which would invalidate this. */
2030 if (dest_reg_was_split)
2032 int regno = REGNO (SET_DEST (set));
2034 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
2035 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
2037 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
2042 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2043 copy = emit_jump_insn (pattern);
2044 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2046 if (JUMP_LABEL (insn) == start_label && insn == copy_end
2047 && ! last_iteration)
2049 /* Update JUMP_LABEL correctly to make invert_jump working. */
2050 JUMP_LABEL (copy) = get_label_from_map (map,
2052 (JUMP_LABEL (insn)));
2053 /* This is a branch to the beginning of the loop; this is the
2054 last insn being copied; and this is not the last iteration.
2055 In this case, we want to change the original fall through
2056 case to be a branch past the end of the loop, and the
2057 original jump label case to fall_through. */
2059 if (!invert_jump (copy, exit_label, 0))
2062 rtx lab = gen_label_rtx ();
2063 /* Can't do it by reversing the jump (probably because we
2064 couldn't reverse the conditions), so emit a new
2065 jump_insn after COPY, and redirect the jump around
2067 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2068 jmp = emit_barrier_after (jmp);
2069 emit_label_after (lab, jmp);
2070 LABEL_NUSES (lab) = 0;
2071 if (!redirect_jump (copy, lab, 0))
2078 try_constants (cc0_insn, map);
2081 try_constants (copy, map);
2083 /* Set the jump label of COPY correctly to avoid problems with
2084 later passes of unroll_loop, if INSN had jump label set. */
2085 if (JUMP_LABEL (insn))
2089 /* Can't use the label_map for every insn, since this may be
2090 the backward branch, and hence the label was not mapped. */
2091 if ((set = single_set (copy)))
2093 tem = SET_SRC (set);
2094 if (GET_CODE (tem) == LABEL_REF)
2095 label = XEXP (tem, 0);
2096 else if (GET_CODE (tem) == IF_THEN_ELSE)
2098 if (XEXP (tem, 1) != pc_rtx)
2099 label = XEXP (XEXP (tem, 1), 0);
2101 label = XEXP (XEXP (tem, 2), 0);
2105 if (label && GET_CODE (label) == CODE_LABEL)
2106 JUMP_LABEL (copy) = label;
2109 /* An unrecognizable jump insn, probably the entry jump
2110 for a switch statement. This label must have been mapped,
2111 so just use the label_map to get the new jump label. */
2113 = get_label_from_map (map,
2114 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2117 /* If this is a non-local jump, then must increase the label
2118 use count so that the label will not be deleted when the
2119 original jump is deleted. */
2120 LABEL_NUSES (JUMP_LABEL (copy))++;
2122 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2123 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2125 rtx pat = PATTERN (copy);
2126 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2127 int len = XVECLEN (pat, diff_vec_p);
2130 for (i = 0; i < len; i++)
2131 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2134 /* If this used to be a conditional jump insn but whose branch
2135 direction is now known, we must do something special. */
2136 if (any_condjump_p (insn) && onlyjump_p (insn) && map->last_pc_value)
2139 /* If the previous insn set cc0 for us, delete it. */
2140 if (sets_cc0_p (PREV_INSN (copy)))
2141 delete_insn (PREV_INSN (copy));
2144 /* If this is now a no-op, delete it. */
2145 if (map->last_pc_value == pc_rtx)
2147 /* Don't let delete_insn delete the label referenced here,
2148 because we might possibly need it later for some other
2149 instruction in the loop. */
2150 if (JUMP_LABEL (copy))
2151 LABEL_NUSES (JUMP_LABEL (copy))++;
2153 if (JUMP_LABEL (copy))
2154 LABEL_NUSES (JUMP_LABEL (copy))--;
2158 /* Otherwise, this is unconditional jump so we must put a
2159 BARRIER after it. We could do some dead code elimination
2160 here, but jump.c will do it just as well. */
2166 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2167 copy = emit_call_insn (pattern);
2168 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2170 /* Because the USAGE information potentially contains objects other
2171 than hard registers, we need to copy it. */
2172 CALL_INSN_FUNCTION_USAGE (copy)
2173 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2178 try_constants (cc0_insn, map);
2181 try_constants (copy, map);
2183 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2184 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2185 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2189 /* If this is the loop start label, then we don't need to emit a
2190 copy of this label since no one will use it. */
2192 if (insn != start_label)
2194 copy = emit_label (get_label_from_map (map,
2195 CODE_LABEL_NUMBER (insn)));
2201 copy = emit_barrier ();
2205 /* VTOP and CONT notes are valid only before the loop exit test.
2206 If placed anywhere else, loop may generate bad code. */
2207 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2208 the associated rtl. We do not want to share the structure in
2211 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2212 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED_LABEL
2213 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2214 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2215 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2216 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2217 copy = emit_note (NOTE_SOURCE_FILE (insn),
2218 NOTE_LINE_NUMBER (insn));
2227 map->insn_map[INSN_UID (insn)] = copy;
2229 while (insn != copy_end);
2231 /* Now finish coping the REG_NOTES. */
2235 insn = NEXT_INSN (insn);
2236 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2237 || GET_CODE (insn) == CALL_INSN)
2238 && map->insn_map[INSN_UID (insn)])
2239 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2241 while (insn != copy_end);
2243 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2244 each of these notes here, since there may be some important ones, such as
2245 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2246 iteration, because the original notes won't be deleted.
2248 We can't use insert_before here, because when from preconditioning,
2249 insert_before points before the loop. We can't use copy_end, because
2250 there may be insns already inserted after it (which we don't want to
2251 copy) when not from preconditioning code. */
2253 if (! last_iteration)
2255 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2257 /* VTOP notes are valid only before the loop exit test.
2258 If placed anywhere else, loop may generate bad code.
2259 There is no need to test for NOTE_INSN_LOOP_CONT notes
2260 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2261 instructions before the last insn in the loop, and if the
2262 end test is that short, there will be a VTOP note between
2263 the CONT note and the test. */
2264 if (GET_CODE (insn) == NOTE
2265 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2266 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2267 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2268 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2272 if (final_label && LABEL_NUSES (final_label) > 0)
2273 emit_label (final_label);
2275 tem = gen_sequence ();
2277 emit_insn_before (tem, insert_before);
2280 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2281 emitted. This will correctly handle the case where the increment value
2282 won't fit in the immediate field of a PLUS insns. */
2285 emit_unrolled_add (dest_reg, src_reg, increment)
2286 rtx dest_reg, src_reg, increment;
2290 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2291 dest_reg, 0, OPTAB_LIB_WIDEN);
2293 if (dest_reg != result)
2294 emit_move_insn (dest_reg, result);
2297 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2298 is a backward branch in that range that branches to somewhere between
2299 LOOP->START and INSN. Returns 0 otherwise. */
2301 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2302 In practice, this is not a problem, because this function is seldom called,
2303 and uses a negligible amount of CPU time on average. */
2306 back_branch_in_range_p (loop, insn)
2307 const struct loop *loop;
2310 rtx p, q, target_insn;
2311 rtx loop_start = loop->start;
2312 rtx loop_end = loop->end;
2313 rtx orig_loop_end = loop->end;
2315 /* Stop before we get to the backward branch at the end of the loop. */
2316 loop_end = prev_nonnote_insn (loop_end);
2317 if (GET_CODE (loop_end) == BARRIER)
2318 loop_end = PREV_INSN (loop_end);
2320 /* Check in case insn has been deleted, search forward for first non
2321 deleted insn following it. */
2322 while (INSN_DELETED_P (insn))
2323 insn = NEXT_INSN (insn);
2325 /* Check for the case where insn is the last insn in the loop. Deal
2326 with the case where INSN was a deleted loop test insn, in which case
2327 it will now be the NOTE_LOOP_END. */
2328 if (insn == loop_end || insn == orig_loop_end)
2331 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2333 if (GET_CODE (p) == JUMP_INSN)
2335 target_insn = JUMP_LABEL (p);
2337 /* Search from loop_start to insn, to see if one of them is
2338 the target_insn. We can't use INSN_LUID comparisons here,
2339 since insn may not have an LUID entry. */
2340 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2341 if (q == target_insn)
2349 /* Try to generate the simplest rtx for the expression
2350 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2354 fold_rtx_mult_add (mult1, mult2, add1, mode)
2355 rtx mult1, mult2, add1;
2356 enum machine_mode mode;
2361 /* The modes must all be the same. This should always be true. For now,
2362 check to make sure. */
2363 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2364 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2365 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2368 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2369 will be a constant. */
2370 if (GET_CODE (mult1) == CONST_INT)
2377 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2379 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2381 /* Again, put the constant second. */
2382 if (GET_CODE (add1) == CONST_INT)
2389 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2391 result = gen_rtx_PLUS (mode, add1, mult_res);
2396 /* Searches the list of induction struct's for the biv BL, to try to calculate
2397 the total increment value for one iteration of the loop as a constant.
2399 Returns the increment value as an rtx, simplified as much as possible,
2400 if it can be calculated. Otherwise, returns 0. */
2403 biv_total_increment (bl)
2404 struct iv_class *bl;
2406 struct induction *v;
2409 /* For increment, must check every instruction that sets it. Each
2410 instruction must be executed only once each time through the loop.
2411 To verify this, we check that the insn is always executed, and that
2412 there are no backward branches after the insn that branch to before it.
2413 Also, the insn must have a mult_val of one (to make sure it really is
2416 result = const0_rtx;
2417 for (v = bl->biv; v; v = v->next_iv)
2419 if (v->always_computable && v->mult_val == const1_rtx
2420 && ! v->maybe_multiple)
2421 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2430 /* For each biv and giv, determine whether it can be safely split into
2431 a different variable for each unrolled copy of the loop body. If it
2432 is safe to split, then indicate that by saving some useful info
2433 in the splittable_regs array.
2435 If the loop is being completely unrolled, then splittable_regs will hold
2436 the current value of the induction variable while the loop is unrolled.
2437 It must be set to the initial value of the induction variable here.
2438 Otherwise, splittable_regs will hold the difference between the current
2439 value of the induction variable and the value the induction variable had
2440 at the top of the loop. It must be set to the value 0 here.
2442 Returns the total number of instructions that set registers that are
2445 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2446 constant values are unnecessary, since we can easily calculate increment
2447 values in this case even if nothing is constant. The increment value
2448 should not involve a multiply however. */
2450 /* ?? Even if the biv/giv increment values aren't constant, it may still
2451 be beneficial to split the variable if the loop is only unrolled a few
2452 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2455 find_splittable_regs (loop, unroll_type, end_insert_before, unroll_number)
2456 const struct loop *loop;
2457 enum unroll_types unroll_type;
2458 rtx end_insert_before;
2461 struct iv_class *bl;
2462 struct induction *v;
2464 rtx biv_final_value;
2467 rtx loop_start = loop->start;
2468 rtx loop_end = loop->end;
2470 for (bl = loop_iv_list; bl; bl = bl->next)
2472 /* Biv_total_increment must return a constant value,
2473 otherwise we can not calculate the split values. */
2475 increment = biv_total_increment (bl);
2476 if (! increment || GET_CODE (increment) != CONST_INT)
2479 /* The loop must be unrolled completely, or else have a known number
2480 of iterations and only one exit, or else the biv must be dead
2481 outside the loop, or else the final value must be known. Otherwise,
2482 it is unsafe to split the biv since it may not have the proper
2483 value on loop exit. */
2485 /* loop_number_exit_count is non-zero if the loop has an exit other than
2486 a fall through at the end. */
2489 biv_final_value = 0;
2490 if (unroll_type != UNROLL_COMPLETELY
2491 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2492 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2494 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2495 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2496 < INSN_LUID (bl->init_insn))
2497 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2498 && ! (biv_final_value = final_biv_value (loop, bl)))
2501 /* If any of the insns setting the BIV don't do so with a simple
2502 PLUS, we don't know how to split it. */
2503 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2504 if ((tem = single_set (v->insn)) == 0
2505 || GET_CODE (SET_DEST (tem)) != REG
2506 || REGNO (SET_DEST (tem)) != bl->regno
2507 || GET_CODE (SET_SRC (tem)) != PLUS)
2510 /* If final value is non-zero, then must emit an instruction which sets
2511 the value of the biv to the proper value. This is done after
2512 handling all of the givs, since some of them may need to use the
2513 biv's value in their initialization code. */
2515 /* This biv is splittable. If completely unrolling the loop, save
2516 the biv's initial value. Otherwise, save the constant zero. */
2518 if (biv_splittable == 1)
2520 if (unroll_type == UNROLL_COMPLETELY)
2522 /* If the initial value of the biv is itself (i.e. it is too
2523 complicated for strength_reduce to compute), or is a hard
2524 register, or it isn't invariant, then we must create a new
2525 pseudo reg to hold the initial value of the biv. */
2527 if (GET_CODE (bl->initial_value) == REG
2528 && (REGNO (bl->initial_value) == bl->regno
2529 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2530 || ! loop_invariant_p (loop, bl->initial_value)))
2532 rtx tem = gen_reg_rtx (bl->biv->mode);
2534 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2535 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2538 if (loop_dump_stream)
2539 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2540 bl->regno, REGNO (tem));
2542 splittable_regs[bl->regno] = tem;
2545 splittable_regs[bl->regno] = bl->initial_value;
2548 splittable_regs[bl->regno] = const0_rtx;
2550 /* Save the number of instructions that modify the biv, so that
2551 we can treat the last one specially. */
2553 splittable_regs_updates[bl->regno] = bl->biv_count;
2554 result += bl->biv_count;
2556 if (loop_dump_stream)
2557 fprintf (loop_dump_stream,
2558 "Biv %d safe to split.\n", bl->regno);
2561 /* Check every giv that depends on this biv to see whether it is
2562 splittable also. Even if the biv isn't splittable, givs which
2563 depend on it may be splittable if the biv is live outside the
2564 loop, and the givs aren't. */
2566 result += find_splittable_givs (loop, bl, unroll_type, increment,
2569 /* If final value is non-zero, then must emit an instruction which sets
2570 the value of the biv to the proper value. This is done after
2571 handling all of the givs, since some of them may need to use the
2572 biv's value in their initialization code. */
2573 if (biv_final_value)
2575 /* If the loop has multiple exits, emit the insns before the
2576 loop to ensure that it will always be executed no matter
2577 how the loop exits. Otherwise emit the insn after the loop,
2578 since this is slightly more efficient. */
2579 if (! loop->exit_count)
2580 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2585 /* Create a new register to hold the value of the biv, and then
2586 set the biv to its final value before the loop start. The biv
2587 is set to its final value before loop start to ensure that
2588 this insn will always be executed, no matter how the loop
2590 rtx tem = gen_reg_rtx (bl->biv->mode);
2591 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2593 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2595 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2599 if (loop_dump_stream)
2600 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2601 REGNO (bl->biv->src_reg), REGNO (tem));
2603 /* Set up the mapping from the original biv register to the new
2605 bl->biv->src_reg = tem;
2612 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2613 for the instruction that is using it. Do not make any changes to that
2617 verify_addresses (v, giv_inc, unroll_number)
2618 struct induction *v;
2623 rtx orig_addr = *v->location;
2624 rtx last_addr = plus_constant (v->dest_reg,
2625 INTVAL (giv_inc) * (unroll_number - 1));
2627 /* First check to see if either address would fail. Handle the fact
2628 that we have may have a match_dup. */
2629 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2630 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2633 /* Now put things back the way they were before. This should always
2635 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2641 /* For every giv based on the biv BL, check to determine whether it is
2642 splittable. This is a subroutine to find_splittable_regs ().
2644 Return the number of instructions that set splittable registers. */
2647 find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
2648 const struct loop *loop;
2649 struct iv_class *bl;
2650 enum unroll_types unroll_type;
2654 struct induction *v, *v2;
2659 /* Scan the list of givs, and set the same_insn field when there are
2660 multiple identical givs in the same insn. */
2661 for (v = bl->giv; v; v = v->next_iv)
2662 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2663 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2667 for (v = bl->giv; v; v = v->next_iv)
2671 /* Only split the giv if it has already been reduced, or if the loop is
2672 being completely unrolled. */
2673 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2676 /* The giv can be split if the insn that sets the giv is executed once
2677 and only once on every iteration of the loop. */
2678 /* An address giv can always be split. v->insn is just a use not a set,
2679 and hence it does not matter whether it is always executed. All that
2680 matters is that all the biv increments are always executed, and we
2681 won't reach here if they aren't. */
2682 if (v->giv_type != DEST_ADDR
2683 && (! v->always_computable
2684 || back_branch_in_range_p (loop, v->insn)))
2687 /* The giv increment value must be a constant. */
2688 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2690 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2693 /* The loop must be unrolled completely, or else have a known number of
2694 iterations and only one exit, or else the giv must be dead outside
2695 the loop, or else the final value of the giv must be known.
2696 Otherwise, it is not safe to split the giv since it may not have the
2697 proper value on loop exit. */
2699 /* The used outside loop test will fail for DEST_ADDR givs. They are
2700 never used outside the loop anyways, so it is always safe to split a
2704 if (unroll_type != UNROLL_COMPLETELY
2705 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2706 && v->giv_type != DEST_ADDR
2707 /* The next part is true if the pseudo is used outside the loop.
2708 We assume that this is true for any pseudo created after loop
2709 starts, because we don't have a reg_n_info entry for them. */
2710 && (REGNO (v->dest_reg) >= max_reg_before_loop
2711 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2712 /* Check for the case where the pseudo is set by a shift/add
2713 sequence, in which case the first insn setting the pseudo
2714 is the first insn of the shift/add sequence. */
2715 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2716 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2717 != INSN_UID (XEXP (tem, 0)))))
2718 /* Line above always fails if INSN was moved by loop opt. */
2719 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2720 >= INSN_LUID (loop->end)))
2721 /* Givs made from biv increments are missed by the above test, so
2722 test explicitly for them. */
2723 && (REGNO (v->dest_reg) < first_increment_giv
2724 || REGNO (v->dest_reg) > last_increment_giv)
2725 && ! (final_value = v->final_value))
2729 /* Currently, non-reduced/final-value givs are never split. */
2730 /* Should emit insns after the loop if possible, as the biv final value
2733 /* If the final value is non-zero, and the giv has not been reduced,
2734 then must emit an instruction to set the final value. */
2735 if (final_value && !v->new_reg)
2737 /* Create a new register to hold the value of the giv, and then set
2738 the giv to its final value before the loop start. The giv is set
2739 to its final value before loop start to ensure that this insn
2740 will always be executed, no matter how we exit. */
2741 tem = gen_reg_rtx (v->mode);
2742 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2743 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2746 if (loop_dump_stream)
2747 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2748 REGNO (v->dest_reg), REGNO (tem));
2754 /* This giv is splittable. If completely unrolling the loop, save the
2755 giv's initial value. Otherwise, save the constant zero for it. */
2757 if (unroll_type == UNROLL_COMPLETELY)
2759 /* It is not safe to use bl->initial_value here, because it may not
2760 be invariant. It is safe to use the initial value stored in
2761 the splittable_regs array if it is set. In rare cases, it won't
2762 be set, so then we do exactly the same thing as
2763 find_splittable_regs does to get a safe value. */
2764 rtx biv_initial_value;
2766 if (splittable_regs[bl->regno])
2767 biv_initial_value = splittable_regs[bl->regno];
2768 else if (GET_CODE (bl->initial_value) != REG
2769 || (REGNO (bl->initial_value) != bl->regno
2770 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2771 biv_initial_value = bl->initial_value;
2774 rtx tem = gen_reg_rtx (bl->biv->mode);
2776 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2777 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2779 biv_initial_value = tem;
2781 biv_initial_value = extend_value_for_giv (v, biv_initial_value);
2782 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2783 v->add_val, v->mode);
2790 /* If a giv was combined with another giv, then we can only split
2791 this giv if the giv it was combined with was reduced. This
2792 is because the value of v->new_reg is meaningless in this
2794 if (v->same && ! v->same->new_reg)
2796 if (loop_dump_stream)
2797 fprintf (loop_dump_stream,
2798 "giv combined with unreduced giv not split.\n");
2801 /* If the giv is an address destination, it could be something other
2802 than a simple register, these have to be treated differently. */
2803 else if (v->giv_type == DEST_REG)
2805 /* If value is not a constant, register, or register plus
2806 constant, then compute its value into a register before
2807 loop start. This prevents invalid rtx sharing, and should
2808 generate better code. We can use bl->initial_value here
2809 instead of splittable_regs[bl->regno] because this code
2810 is going before the loop start. */
2811 if (unroll_type == UNROLL_COMPLETELY
2812 && GET_CODE (value) != CONST_INT
2813 && GET_CODE (value) != REG
2814 && (GET_CODE (value) != PLUS
2815 || GET_CODE (XEXP (value, 0)) != REG
2816 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2818 rtx tem = gen_reg_rtx (v->mode);
2819 record_base_value (REGNO (tem), v->add_val, 0);
2820 emit_iv_add_mult (bl->initial_value, v->mult_val,
2821 v->add_val, tem, loop->start);
2825 splittable_regs[REGNO (v->new_reg)] = value;
2826 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2830 /* Splitting address givs is useful since it will often allow us
2831 to eliminate some increment insns for the base giv as
2834 /* If the addr giv is combined with a dest_reg giv, then all
2835 references to that dest reg will be remapped, which is NOT
2836 what we want for split addr regs. We always create a new
2837 register for the split addr giv, just to be safe. */
2839 /* If we have multiple identical address givs within a
2840 single instruction, then use a single pseudo reg for
2841 both. This is necessary in case one is a match_dup
2844 v->const_adjust = 0;
2848 v->dest_reg = v->same_insn->dest_reg;
2849 if (loop_dump_stream)
2850 fprintf (loop_dump_stream,
2851 "Sharing address givs in insn %d\n",
2852 INSN_UID (v->insn));
2854 /* If multiple address GIVs have been combined with the
2855 same dest_reg GIV, do not create a new register for
2857 else if (unroll_type != UNROLL_COMPLETELY
2858 && v->giv_type == DEST_ADDR
2859 && v->same && v->same->giv_type == DEST_ADDR
2860 && v->same->unrolled
2861 /* combine_givs_p may return true for some cases
2862 where the add and mult values are not equal.
2863 To share a register here, the values must be
2865 && rtx_equal_p (v->same->mult_val, v->mult_val)
2866 && rtx_equal_p (v->same->add_val, v->add_val)
2867 /* If the memory references have different modes,
2868 then the address may not be valid and we must
2869 not share registers. */
2870 && verify_addresses (v, giv_inc, unroll_number))
2872 v->dest_reg = v->same->dest_reg;
2875 else if (unroll_type != UNROLL_COMPLETELY)
2877 /* If not completely unrolling the loop, then create a new
2878 register to hold the split value of the DEST_ADDR giv.
2879 Emit insn to initialize its value before loop start. */
2881 rtx tem = gen_reg_rtx (v->mode);
2882 struct induction *same = v->same;
2883 rtx new_reg = v->new_reg;
2884 record_base_value (REGNO (tem), v->add_val, 0);
2886 if (same && same->derived_from)
2888 /* calculate_giv_inc doesn't work for derived givs.
2889 copy_loop_body works around the problem for the
2890 DEST_REG givs themselves, but it can't handle
2891 DEST_ADDR givs that have been combined with
2892 a derived DEST_REG giv.
2893 So Handle V as if the giv from which V->SAME has
2894 been derived has been combined with V.
2895 recombine_givs only derives givs from givs that
2896 are reduced the ordinary, so we need not worry
2897 about same->derived_from being in turn derived. */
2899 same = same->derived_from;
2900 new_reg = express_from (same, v);
2901 new_reg = replace_rtx (new_reg, same->dest_reg,
2905 /* If the address giv has a constant in its new_reg value,
2906 then this constant can be pulled out and put in value,
2907 instead of being part of the initialization code. */
2909 if (GET_CODE (new_reg) == PLUS
2910 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
2913 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
2915 /* Only succeed if this will give valid addresses.
2916 Try to validate both the first and the last
2917 address resulting from loop unrolling, if
2918 one fails, then can't do const elim here. */
2919 if (verify_addresses (v, giv_inc, unroll_number))
2921 /* Save the negative of the eliminated const, so
2922 that we can calculate the dest_reg's increment
2924 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
2926 new_reg = XEXP (new_reg, 0);
2927 if (loop_dump_stream)
2928 fprintf (loop_dump_stream,
2929 "Eliminating constant from giv %d\n",
2938 /* If the address hasn't been checked for validity yet, do so
2939 now, and fail completely if either the first or the last
2940 unrolled copy of the address is not a valid address
2941 for the instruction that uses it. */
2942 if (v->dest_reg == tem
2943 && ! verify_addresses (v, giv_inc, unroll_number))
2945 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2946 if (v2->same_insn == v)
2949 if (loop_dump_stream)
2950 fprintf (loop_dump_stream,
2951 "Invalid address for giv at insn %d\n",
2952 INSN_UID (v->insn));
2956 v->new_reg = new_reg;
2959 /* We set this after the address check, to guarantee that
2960 the register will be initialized. */
2963 /* To initialize the new register, just move the value of
2964 new_reg into it. This is not guaranteed to give a valid
2965 instruction on machines with complex addressing modes.
2966 If we can't recognize it, then delete it and emit insns
2967 to calculate the value from scratch. */
2968 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
2969 copy_rtx (v->new_reg)),
2971 if (recog_memoized (PREV_INSN (loop->start)) < 0)
2975 /* We can't use bl->initial_value to compute the initial
2976 value, because the loop may have been preconditioned.
2977 We must calculate it from NEW_REG. Try using
2978 force_operand instead of emit_iv_add_mult. */
2979 delete_insn (PREV_INSN (loop->start));
2982 ret = force_operand (v->new_reg, tem);
2984 emit_move_insn (tem, ret);
2985 sequence = gen_sequence ();
2987 emit_insn_before (sequence, loop->start);
2989 if (loop_dump_stream)
2990 fprintf (loop_dump_stream,
2991 "Invalid init insn, rewritten.\n");
2996 v->dest_reg = value;
2998 /* Check the resulting address for validity, and fail
2999 if the resulting address would be invalid. */
3000 if (! verify_addresses (v, giv_inc, unroll_number))
3002 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3003 if (v2->same_insn == v)
3006 if (loop_dump_stream)
3007 fprintf (loop_dump_stream,
3008 "Invalid address for giv at insn %d\n",
3009 INSN_UID (v->insn));
3012 if (v->same && v->same->derived_from)
3014 /* Handle V as if the giv from which V->SAME has
3015 been derived has been combined with V. */
3017 v->same = v->same->derived_from;
3018 v->new_reg = express_from (v->same, v);
3019 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3025 /* Store the value of dest_reg into the insn. This sharing
3026 will not be a problem as this insn will always be copied
3029 *v->location = v->dest_reg;
3031 /* If this address giv is combined with a dest reg giv, then
3032 save the base giv's induction pointer so that we will be
3033 able to handle this address giv properly. The base giv
3034 itself does not have to be splittable. */
3036 if (v->same && v->same->giv_type == DEST_REG)
3037 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3039 if (GET_CODE (v->new_reg) == REG)
3041 /* This giv maybe hasn't been combined with any others.
3042 Make sure that it's giv is marked as splittable here. */
3044 splittable_regs[REGNO (v->new_reg)] = value;
3045 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3047 /* Make it appear to depend upon itself, so that the
3048 giv will be properly split in the main loop above. */
3052 addr_combined_regs[REGNO (v->new_reg)] = v;
3056 if (loop_dump_stream)
3057 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3063 /* Currently, unreduced giv's can't be split. This is not too much
3064 of a problem since unreduced giv's are not live across loop
3065 iterations anyways. When unrolling a loop completely though,
3066 it makes sense to reduce&split givs when possible, as this will
3067 result in simpler instructions, and will not require that a reg
3068 be live across loop iterations. */
3070 splittable_regs[REGNO (v->dest_reg)] = value;
3071 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3072 REGNO (v->dest_reg), INSN_UID (v->insn));
3078 /* Unreduced givs are only updated once by definition. Reduced givs
3079 are updated as many times as their biv is. Mark it so if this is
3080 a splittable register. Don't need to do anything for address givs
3081 where this may not be a register. */
3083 if (GET_CODE (v->new_reg) == REG)
3087 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3089 if (count > 1 && v->derived_from)
3090 /* In this case, there is one set where the giv insn was and one
3091 set each after each biv increment. (Most are likely dead.) */
3094 splittable_regs_updates[REGNO (v->new_reg)] = count;
3099 if (loop_dump_stream)
3103 if (GET_CODE (v->dest_reg) == CONST_INT)
3105 else if (GET_CODE (v->dest_reg) != REG)
3106 regnum = REGNO (XEXP (v->dest_reg, 0));
3108 regnum = REGNO (v->dest_reg);
3109 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3110 regnum, INSN_UID (v->insn));
3117 /* Try to prove that the register is dead after the loop exits. Trace every
3118 loop exit looking for an insn that will always be executed, which sets
3119 the register to some value, and appears before the first use of the register
3120 is found. If successful, then return 1, otherwise return 0. */
3122 /* ?? Could be made more intelligent in the handling of jumps, so that
3123 it can search past if statements and other similar structures. */
3126 reg_dead_after_loop (loop, reg)
3127 const struct loop *loop;
3133 int label_count = 0;
3135 /* In addition to checking all exits of this loop, we must also check
3136 all exits of inner nested loops that would exit this loop. We don't
3137 have any way to identify those, so we just give up if there are any
3138 such inner loop exits. */
3140 for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
3143 if (label_count != loop->exit_count)
3146 /* HACK: Must also search the loop fall through exit, create a label_ref
3147 here which points to the loop->end, and append the loop_number_exit_labels
3149 label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
3150 LABEL_NEXTREF (label) = loop->exit_labels;
3152 for ( ; label; label = LABEL_NEXTREF (label))
3154 /* Succeed if find an insn which sets the biv or if reach end of
3155 function. Fail if find an insn that uses the biv, or if come to
3156 a conditional jump. */
3158 insn = NEXT_INSN (XEXP (label, 0));
3161 code = GET_CODE (insn);
3162 if (GET_RTX_CLASS (code) == 'i')
3166 if (reg_referenced_p (reg, PATTERN (insn)))
3169 set = single_set (insn);
3170 if (set && rtx_equal_p (SET_DEST (set), reg))
3174 if (code == JUMP_INSN)
3176 if (GET_CODE (PATTERN (insn)) == RETURN)
3178 else if (!any_uncondjump_p (insn)
3179 /* Prevent infinite loop following infinite loops. */
3180 || jump_count++ > 20)
3183 insn = JUMP_LABEL (insn);
3186 insn = NEXT_INSN (insn);
3190 /* Success, the register is dead on all loop exits. */
3194 /* Try to calculate the final value of the biv, the value it will have at
3195 the end of the loop. If we can do it, return that value. */
3198 final_biv_value (loop, bl)
3199 const struct loop *loop;
3200 struct iv_class *bl;
3202 rtx loop_end = loop->end;
3203 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3206 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3208 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3211 /* The final value for reversed bivs must be calculated differently than
3212 for ordinary bivs. In this case, there is already an insn after the
3213 loop which sets this biv's final value (if necessary), and there are
3214 no other loop exits, so we can return any value. */
3217 if (loop_dump_stream)
3218 fprintf (loop_dump_stream,
3219 "Final biv value for %d, reversed biv.\n", bl->regno);
3224 /* Try to calculate the final value as initial value + (number of iterations
3225 * increment). For this to work, increment must be invariant, the only
3226 exit from the loop must be the fall through at the bottom (otherwise
3227 it may not have its final value when the loop exits), and the initial
3228 value of the biv must be invariant. */
3230 if (n_iterations != 0
3231 && ! loop->exit_count
3232 && loop_invariant_p (loop, bl->initial_value))
3234 increment = biv_total_increment (bl);
3236 if (increment && loop_invariant_p (loop, increment))
3238 /* Can calculate the loop exit value, emit insns after loop
3239 end to calculate this value into a temporary register in
3240 case it is needed later. */
3242 tem = gen_reg_rtx (bl->biv->mode);
3243 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3244 /* Make sure loop_end is not the last insn. */
3245 if (NEXT_INSN (loop_end) == 0)
3246 emit_note_after (NOTE_INSN_DELETED, loop_end);
3247 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3248 bl->initial_value, tem, NEXT_INSN (loop_end));
3250 if (loop_dump_stream)
3251 fprintf (loop_dump_stream,
3252 "Final biv value for %d, calculated.\n", bl->regno);
3258 /* Check to see if the biv is dead at all loop exits. */
3259 if (reg_dead_after_loop (loop, bl->biv->src_reg))
3261 if (loop_dump_stream)
3262 fprintf (loop_dump_stream,
3263 "Final biv value for %d, biv dead after loop exit.\n",
3272 /* Try to calculate the final value of the giv, the value it will have at
3273 the end of the loop. If we can do it, return that value. */
3276 final_giv_value (loop, v)
3277 const struct loop *loop;
3278 struct induction *v;
3280 struct iv_class *bl;
3283 rtx insert_before, seq;
3284 rtx loop_end = loop->end;
3285 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3287 bl = reg_biv_class[REGNO (v->src_reg)];
3289 /* The final value for givs which depend on reversed bivs must be calculated
3290 differently than for ordinary givs. In this case, there is already an
3291 insn after the loop which sets this giv's final value (if necessary),
3292 and there are no other loop exits, so we can return any value. */
3295 if (loop_dump_stream)
3296 fprintf (loop_dump_stream,
3297 "Final giv value for %d, depends on reversed biv\n",
3298 REGNO (v->dest_reg));
3302 /* Try to calculate the final value as a function of the biv it depends
3303 upon. The only exit from the loop must be the fall through at the bottom
3304 (otherwise it may not have its final value when the loop exits). */
3306 /* ??? Can calculate the final giv value by subtracting off the
3307 extra biv increments times the giv's mult_val. The loop must have
3308 only one exit for this to work, but the loop iterations does not need
3311 if (n_iterations != 0
3312 && ! loop->exit_count)
3314 /* ?? It is tempting to use the biv's value here since these insns will
3315 be put after the loop, and hence the biv will have its final value
3316 then. However, this fails if the biv is subsequently eliminated.
3317 Perhaps determine whether biv's are eliminable before trying to
3318 determine whether giv's are replaceable so that we can use the
3319 biv value here if it is not eliminable. */
3321 /* We are emitting code after the end of the loop, so we must make
3322 sure that bl->initial_value is still valid then. It will still
3323 be valid if it is invariant. */
3325 increment = biv_total_increment (bl);
3327 if (increment && loop_invariant_p (loop, increment)
3328 && loop_invariant_p (loop, bl->initial_value))
3330 /* Can calculate the loop exit value of its biv as
3331 (n_iterations * increment) + initial_value */
3333 /* The loop exit value of the giv is then
3334 (final_biv_value - extra increments) * mult_val + add_val.
3335 The extra increments are any increments to the biv which
3336 occur in the loop after the giv's value is calculated.
3337 We must search from the insn that sets the giv to the end
3338 of the loop to calculate this value. */
3340 insert_before = NEXT_INSN (loop_end);
3342 /* Put the final biv value in tem. */
3343 tem = gen_reg_rtx (v->mode);
3344 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3345 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3346 extend_value_for_giv (v, bl->initial_value),
3347 tem, insert_before);
3349 /* Subtract off extra increments as we find them. */
3350 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3351 insn = NEXT_INSN (insn))
3353 struct induction *biv;
3355 for (biv = bl->biv; biv; biv = biv->next_iv)
3356 if (biv->insn == insn)
3359 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3360 biv->add_val, NULL_RTX, 0,
3362 seq = gen_sequence ();
3364 emit_insn_before (seq, insert_before);
3368 /* Now calculate the giv's final value. */
3369 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3372 if (loop_dump_stream)
3373 fprintf (loop_dump_stream,
3374 "Final giv value for %d, calc from biv's value.\n",
3375 REGNO (v->dest_reg));
3381 /* Replaceable giv's should never reach here. */
3385 /* Check to see if the biv is dead at all loop exits. */
3386 if (reg_dead_after_loop (loop, v->dest_reg))
3388 if (loop_dump_stream)
3389 fprintf (loop_dump_stream,
3390 "Final giv value for %d, giv dead after loop exit.\n",
3391 REGNO (v->dest_reg));
3400 /* Look back before LOOP->START for then insn that sets REG and return
3401 the equivalent constant if there is a REG_EQUAL note otherwise just
3402 the SET_SRC of REG. */
3405 loop_find_equiv_value (loop, reg)
3406 const struct loop *loop;
3409 rtx loop_start = loop->start;
3414 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3416 if (GET_CODE (insn) == CODE_LABEL)
3419 else if (INSN_P (insn) && reg_set_p (reg, insn))
3421 /* We found the last insn before the loop that sets the register.
3422 If it sets the entire register, and has a REG_EQUAL note,
3423 then use the value of the REG_EQUAL note. */
3424 if ((set = single_set (insn))
3425 && (SET_DEST (set) == reg))
3427 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3429 /* Only use the REG_EQUAL note if it is a constant.
3430 Other things, divide in particular, will cause
3431 problems later if we use them. */
3432 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3433 && CONSTANT_P (XEXP (note, 0)))
3434 ret = XEXP (note, 0);
3436 ret = SET_SRC (set);
3438 /* We cannot do this if it changes between the
3439 assignment and loop start though. */
3440 if (modified_between_p (ret, insn, loop_start))
3449 /* Return a simplified rtx for the expression OP - REG.
3451 REG must appear in OP, and OP must be a register or the sum of a register
3454 Thus, the return value must be const0_rtx or the second term.
3456 The caller is responsible for verifying that REG appears in OP and OP has
3460 subtract_reg_term (op, reg)
3465 if (GET_CODE (op) == PLUS)
3467 if (XEXP (op, 0) == reg)
3468 return XEXP (op, 1);
3469 else if (XEXP (op, 1) == reg)
3470 return XEXP (op, 0);
3472 /* OP does not contain REG as a term. */
3477 /* Find and return register term common to both expressions OP0 and
3478 OP1 or NULL_RTX if no such term exists. Each expression must be a
3479 REG or a PLUS of a REG. */
3482 find_common_reg_term (op0, op1)
3485 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3486 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3493 if (GET_CODE (op0) == PLUS)
3494 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3496 op01 = const0_rtx, op00 = op0;
3498 if (GET_CODE (op1) == PLUS)
3499 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3501 op11 = const0_rtx, op10 = op1;
3503 /* Find and return common register term if present. */
3504 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3506 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3510 /* No common register term found. */
3515 /* Determine the loop iterator and calculate the number of loop
3516 iterations. Returns the exact number of loop iterations if it can
3517 be calculated, otherwise returns zero. */
3519 unsigned HOST_WIDE_INT
3520 loop_iterations (loop)
3523 rtx comparison, comparison_value;
3524 rtx iteration_var, initial_value, increment, final_value;
3525 enum rtx_code comparison_code;
3526 HOST_WIDE_INT abs_inc;
3527 unsigned HOST_WIDE_INT abs_diff;
3530 int unsigned_p, compare_dir, final_larger;
3533 struct loop_info *loop_info = LOOP_INFO (loop);
3534 struct iv_class *bl;
3536 loop_info->n_iterations = 0;
3537 loop_info->initial_value = 0;
3538 loop_info->initial_equiv_value = 0;
3539 loop_info->comparison_value = 0;
3540 loop_info->final_value = 0;
3541 loop_info->final_equiv_value = 0;
3542 loop_info->increment = 0;
3543 loop_info->iteration_var = 0;
3544 loop_info->unroll_number = 1;
3547 /* We used to use prev_nonnote_insn here, but that fails because it might
3548 accidentally get the branch for a contained loop if the branch for this
3549 loop was deleted. We can only trust branches immediately before the
3551 last_loop_insn = PREV_INSN (loop->end);
3553 /* ??? We should probably try harder to find the jump insn
3554 at the end of the loop. The following code assumes that
3555 the last loop insn is a jump to the top of the loop. */
3556 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3558 if (loop_dump_stream)
3559 fprintf (loop_dump_stream,
3560 "Loop iterations: No final conditional branch found.\n");
3564 /* If there is a more than a single jump to the top of the loop
3565 we cannot (easily) determine the iteration count. */
3566 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3568 if (loop_dump_stream)
3569 fprintf (loop_dump_stream,
3570 "Loop iterations: Loop has multiple back edges.\n");
3574 /* Find the iteration variable. If the last insn is a conditional
3575 branch, and the insn before tests a register value, make that the
3576 iteration variable. */
3578 comparison = get_condition_for_loop (loop, last_loop_insn);
3579 if (comparison == 0)
3581 if (loop_dump_stream)
3582 fprintf (loop_dump_stream,
3583 "Loop iterations: No final comparison found.\n");
3587 /* ??? Get_condition may switch position of induction variable and
3588 invariant register when it canonicalizes the comparison. */
3590 comparison_code = GET_CODE (comparison);
3591 iteration_var = XEXP (comparison, 0);
3592 comparison_value = XEXP (comparison, 1);
3594 if (GET_CODE (iteration_var) != REG)
3596 if (loop_dump_stream)
3597 fprintf (loop_dump_stream,
3598 "Loop iterations: Comparison not against register.\n");
3602 /* The only new registers that are created before loop iterations
3603 are givs made from biv increments or registers created by
3604 load_mems. In the latter case, it is possible that try_copy_prop
3605 will propagate a new pseudo into the old iteration register but
3606 this will be marked by having the REG_USERVAR_P bit set. */
3608 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements
3609 && ! REG_USERVAR_P (iteration_var))
3612 /* Determine the initial value of the iteration variable, and the amount
3613 that it is incremented each loop. Use the tables constructed by
3614 the strength reduction pass to calculate these values. */
3616 /* Clear the result values, in case no answer can be found. */
3620 /* The iteration variable can be either a giv or a biv. Check to see
3621 which it is, and compute the variable's initial value, and increment
3622 value if possible. */
3624 /* If this is a new register, can't handle it since we don't have any
3625 reg_iv_type entry for it. */
3626 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
3628 if (loop_dump_stream)
3629 fprintf (loop_dump_stream,
3630 "Loop iterations: No reg_iv_type entry for iteration var.\n");
3634 /* Reject iteration variables larger than the host wide int size, since they
3635 could result in a number of iterations greater than the range of our
3636 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
3637 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
3638 > HOST_BITS_PER_WIDE_INT))
3640 if (loop_dump_stream)
3641 fprintf (loop_dump_stream,
3642 "Loop iterations: Iteration var rejected because mode too large.\n");
3645 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
3647 if (loop_dump_stream)
3648 fprintf (loop_dump_stream,
3649 "Loop iterations: Iteration var not an integer.\n");
3652 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
3654 /* When reg_iv_type / reg_iv_info is resized for biv increments
3655 that are turned into givs, reg_biv_class is not resized.
3656 So check here that we don't make an out-of-bounds access. */
3657 if (REGNO (iteration_var) >= max_reg_before_loop)
3660 /* Grab initial value, only useful if it is a constant. */
3661 bl = reg_biv_class[REGNO (iteration_var)];
3662 initial_value = bl->initial_value;
3664 increment = biv_total_increment (bl);
3666 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
3668 HOST_WIDE_INT offset = 0;
3669 struct induction *v = REG_IV_INFO (REGNO (iteration_var));
3670 rtx biv_initial_value;
3672 if (REGNO (v->src_reg) >= max_reg_before_loop)
3675 bl = reg_biv_class[REGNO (v->src_reg)];
3677 /* Increment value is mult_val times the increment value of the biv. */
3679 increment = biv_total_increment (bl);
3682 struct induction *biv_inc;
3685 = fold_rtx_mult_add (v->mult_val, increment, const0_rtx, v->mode);
3686 /* The caller assumes that one full increment has occured at the
3687 first loop test. But that's not true when the biv is incremented
3688 after the giv is set (which is the usual case), e.g.:
3689 i = 6; do {;} while (i++ < 9) .
3690 Therefore, we bias the initial value by subtracting the amount of
3691 the increment that occurs between the giv set and the giv test. */
3692 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
3694 if (loop_insn_first_p (v->insn, biv_inc->insn))
3695 offset -= INTVAL (biv_inc->add_val);
3697 offset *= INTVAL (v->mult_val);
3699 if (loop_dump_stream)
3700 fprintf (loop_dump_stream,
3701 "Loop iterations: Giv iterator, initial value bias %ld.\n",
3704 /* Initial value is mult_val times the biv's initial value plus
3705 add_val. Only useful if it is a constant. */
3706 biv_initial_value = extend_value_for_giv (v, bl->initial_value);
3708 = fold_rtx_mult_add (v->mult_val,
3709 plus_constant (biv_initial_value, offset),
3710 v->add_val, v->mode);
3714 if (loop_dump_stream)
3715 fprintf (loop_dump_stream,
3716 "Loop iterations: Not basic or general induction var.\n");
3720 if (initial_value == 0)
3725 switch (comparison_code)
3740 /* Cannot determine loop iterations with this case. */
3759 /* If the comparison value is an invariant register, then try to find
3760 its value from the insns before the start of the loop. */
3762 final_value = comparison_value;
3763 if (GET_CODE (comparison_value) == REG
3764 && loop_invariant_p (loop, comparison_value))
3766 final_value = loop_find_equiv_value (loop, comparison_value);
3768 /* If we don't get an invariant final value, we are better
3769 off with the original register. */
3770 if (! loop_invariant_p (loop, final_value))
3771 final_value = comparison_value;
3774 /* Calculate the approximate final value of the induction variable
3775 (on the last successful iteration). The exact final value
3776 depends on the branch operator, and increment sign. It will be
3777 wrong if the iteration variable is not incremented by one each
3778 time through the loop and (comparison_value + off_by_one -
3779 initial_value) % increment != 0.
3780 ??? Note that the final_value may overflow and thus final_larger
3781 will be bogus. A potentially infinite loop will be classified
3782 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3784 final_value = plus_constant (final_value, off_by_one);
3786 /* Save the calculated values describing this loop's bounds, in case
3787 precondition_loop_p will need them later. These values can not be
3788 recalculated inside precondition_loop_p because strength reduction
3789 optimizations may obscure the loop's structure.
3791 These values are only required by precondition_loop_p and insert_bct
3792 whenever the number of iterations cannot be computed at compile time.
3793 Only the difference between final_value and initial_value is
3794 important. Note that final_value is only approximate. */
3795 loop_info->initial_value = initial_value;
3796 loop_info->comparison_value = comparison_value;
3797 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3798 loop_info->increment = increment;
3799 loop_info->iteration_var = iteration_var;
3800 loop_info->comparison_code = comparison_code;
3803 /* Try to determine the iteration count for loops such
3804 as (for i = init; i < init + const; i++). When running the
3805 loop optimization twice, the first pass often converts simple
3806 loops into this form. */
3808 if (REG_P (initial_value))
3814 reg1 = initial_value;
3815 if (GET_CODE (final_value) == PLUS)
3816 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3818 reg2 = final_value, const2 = const0_rtx;
3820 /* Check for initial_value = reg1, final_value = reg2 + const2,
3821 where reg1 != reg2. */
3822 if (REG_P (reg2) && reg2 != reg1)
3826 /* Find what reg1 is equivalent to. Hopefully it will
3827 either be reg2 or reg2 plus a constant. */
3828 temp = loop_find_equiv_value (loop, reg1);
3830 if (find_common_reg_term (temp, reg2))
3831 initial_value = temp;
3834 /* Find what reg2 is equivalent to. Hopefully it will
3835 either be reg1 or reg1 plus a constant. Let's ignore
3836 the latter case for now since it is not so common. */
3837 temp = loop_find_equiv_value (loop, reg2);
3839 if (temp == loop_info->iteration_var)
3840 temp = initial_value;
3842 final_value = (const2 == const0_rtx)
3843 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3846 else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
3850 /* When running the loop optimizer twice, check_dbra_loop
3851 further obfuscates reversible loops of the form:
3852 for (i = init; i < init + const; i++). We often end up with
3853 final_value = 0, initial_value = temp, temp = temp2 - init,
3854 where temp2 = init + const. If the loop has a vtop we
3855 can replace initial_value with const. */
3857 temp = loop_find_equiv_value (loop, reg1);
3859 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3861 rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
3863 if (GET_CODE (temp2) == PLUS
3864 && XEXP (temp2, 0) == XEXP (temp, 1))
3865 initial_value = XEXP (temp2, 1);
3870 /* If have initial_value = reg + const1 and final_value = reg +
3871 const2, then replace initial_value with const1 and final_value
3872 with const2. This should be safe since we are protected by the
3873 initial comparison before entering the loop if we have a vtop.
3874 For example, a + b < a + c is not equivalent to b < c for all a
3875 when using modulo arithmetic.
3877 ??? Without a vtop we could still perform the optimization if we check
3878 the initial and final values carefully. */
3880 && (reg_term = find_common_reg_term (initial_value, final_value)))
3882 initial_value = subtract_reg_term (initial_value, reg_term);
3883 final_value = subtract_reg_term (final_value, reg_term);
3886 loop_info->initial_equiv_value = initial_value;
3887 loop_info->final_equiv_value = final_value;
3889 /* For EQ comparison loops, we don't have a valid final value.
3890 Check this now so that we won't leave an invalid value if we
3891 return early for any other reason. */
3892 if (comparison_code == EQ)
3893 loop_info->final_equiv_value = loop_info->final_value = 0;
3897 if (loop_dump_stream)
3898 fprintf (loop_dump_stream,
3899 "Loop iterations: Increment value can't be calculated.\n");
3903 if (GET_CODE (increment) != CONST_INT)
3905 /* If we have a REG, check to see if REG holds a constant value. */
3906 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3907 clear if it is worthwhile to try to handle such RTL. */
3908 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3909 increment = loop_find_equiv_value (loop, increment);
3911 if (GET_CODE (increment) != CONST_INT)
3913 if (loop_dump_stream)
3915 fprintf (loop_dump_stream,
3916 "Loop iterations: Increment value not constant ");
3917 print_rtl (loop_dump_stream, increment);
3918 fprintf (loop_dump_stream, ".\n");
3922 loop_info->increment = increment;
3925 if (GET_CODE (initial_value) != CONST_INT)
3927 if (loop_dump_stream)
3929 fprintf (loop_dump_stream,
3930 "Loop iterations: Initial value not constant ");
3931 print_rtl (loop_dump_stream, initial_value);
3932 fprintf (loop_dump_stream, ".\n");
3936 else if (comparison_code == EQ)
3938 if (loop_dump_stream)
3939 fprintf (loop_dump_stream,
3940 "Loop iterations: EQ comparison loop.\n");
3943 else if (GET_CODE (final_value) != CONST_INT)
3945 if (loop_dump_stream)
3947 fprintf (loop_dump_stream,
3948 "Loop iterations: Final value not constant ");
3949 print_rtl (loop_dump_stream, final_value);
3950 fprintf (loop_dump_stream, ".\n");
3955 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3958 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3959 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3960 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3961 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3963 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3964 - (INTVAL (final_value) < INTVAL (initial_value));
3966 if (INTVAL (increment) > 0)
3968 else if (INTVAL (increment) == 0)
3973 /* There are 27 different cases: compare_dir = -1, 0, 1;
3974 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3975 There are 4 normal cases, 4 reverse cases (where the iteration variable
3976 will overflow before the loop exits), 4 infinite loop cases, and 15
3977 immediate exit (0 or 1 iteration depending on loop type) cases.
3978 Only try to optimize the normal cases. */
3980 /* (compare_dir/final_larger/increment_dir)
3981 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3982 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3983 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3984 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3986 /* ?? If the meaning of reverse loops (where the iteration variable
3987 will overflow before the loop exits) is undefined, then could
3988 eliminate all of these special checks, and just always assume
3989 the loops are normal/immediate/infinite. Note that this means
3990 the sign of increment_dir does not have to be known. Also,
3991 since it does not really hurt if immediate exit loops or infinite loops
3992 are optimized, then that case could be ignored also, and hence all
3993 loops can be optimized.
3995 According to ANSI Spec, the reverse loop case result is undefined,
3996 because the action on overflow is undefined.
3998 See also the special test for NE loops below. */
4000 if (final_larger == increment_dir && final_larger != 0
4001 && (final_larger == compare_dir || compare_dir == 0))
4006 if (loop_dump_stream)
4007 fprintf (loop_dump_stream,
4008 "Loop iterations: Not normal loop.\n");
4012 /* Calculate the number of iterations, final_value is only an approximation,
4013 so correct for that. Note that abs_diff and n_iterations are
4014 unsigned, because they can be as large as 2^n - 1. */
4016 abs_inc = INTVAL (increment);
4018 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
4019 else if (abs_inc < 0)
4021 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
4027 /* For NE tests, make sure that the iteration variable won't miss
4028 the final value. If abs_diff mod abs_incr is not zero, then the
4029 iteration variable will overflow before the loop exits, and we
4030 can not calculate the number of iterations. */
4031 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4034 /* Note that the number of iterations could be calculated using
4035 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4036 handle potential overflow of the summation. */
4037 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4038 return loop_info->n_iterations;
4042 /* Replace uses of split bivs with their split pseudo register. This is
4043 for original instructions which remain after loop unrolling without
4047 remap_split_bivs (x)
4050 register enum rtx_code code;
4052 register const char *fmt;
4057 code = GET_CODE (x);
4072 /* If non-reduced/final-value givs were split, then this would also
4073 have to remap those givs also. */
4075 if (REGNO (x) < max_reg_before_loop
4076 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
4077 return reg_biv_class[REGNO (x)]->biv->src_reg;
4084 fmt = GET_RTX_FORMAT (code);
4085 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4088 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
4089 else if (fmt[i] == 'E')
4092 for (j = 0; j < XVECLEN (x, i); j++)
4093 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
4099 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4100 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4101 return 0. COPY_START is where we can start looking for the insns
4102 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4105 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4106 must dominate LAST_UID.
4108 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4109 may not dominate LAST_UID.
4111 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4112 must dominate LAST_UID. */
4115 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4122 int passed_jump = 0;
4123 rtx p = NEXT_INSN (copy_start);
4125 while (INSN_UID (p) != first_uid)
4127 if (GET_CODE (p) == JUMP_INSN)
4129 /* Could not find FIRST_UID. */
4135 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4136 if (! INSN_P (p) || ! dead_or_set_regno_p (p, regno))
4139 /* FIRST_UID is always executed. */
4140 if (passed_jump == 0)
4143 while (INSN_UID (p) != last_uid)
4145 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4146 can not be sure that FIRST_UID dominates LAST_UID. */
4147 if (GET_CODE (p) == CODE_LABEL)
4149 /* Could not find LAST_UID, but we reached the end of the loop, so
4151 else if (p == copy_end)
4156 /* FIRST_UID is always executed if LAST_UID is executed. */
4160 /* This routine is called when the number of iterations for the unrolled
4161 loop is one. The goal is to identify a loop that begins with an
4162 unconditional branch to the loop continuation note (or a label just after).
4163 In this case, the unconditional branch that starts the loop needs to be
4164 deleted so that we execute the single iteration. */
4166 ujump_to_loop_cont (loop_start, loop_cont)
4170 rtx x, label, label_ref;
4172 /* See if loop start, or the next insn is an unconditional jump. */
4173 loop_start = next_nonnote_insn (loop_start);
4175 x = pc_set (loop_start);
4179 label_ref = SET_SRC (x);
4183 /* Examine insn after loop continuation note. Return if not a label. */
4184 label = next_nonnote_insn (loop_cont);
4185 if (label == 0 || GET_CODE (label) != CODE_LABEL)
4188 /* Return the loop start if the branch label matches the code label. */
4189 if (CODE_LABEL_NUMBER (label) == CODE_LABEL_NUMBER (XEXP (label_ref,0)))