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"
164 /* This controls which loops are unrolled, and by how much we unroll
167 #ifndef MAX_UNROLLED_INSNS
168 #define MAX_UNROLLED_INSNS 100
171 /* Indexed by register number, if non-zero, then it contains a pointer
172 to a struct induction for a DEST_REG giv which has been combined with
173 one of more address givs. This is needed because whenever such a DEST_REG
174 giv is modified, we must modify the value of all split address givs
175 that were combined with this DEST_REG giv. */
177 static struct induction **addr_combined_regs;
179 /* Indexed by register number, if this is a splittable induction variable,
180 then this will hold the current value of the register, which depends on the
183 static rtx *splittable_regs;
185 /* Indexed by register number, if this is a splittable induction variable,
186 this indicates if it was made from a derived giv. */
187 static char *derived_regs;
189 /* Indexed by register number, if this is a splittable induction variable,
190 then this will hold the number of instructions in the loop that modify
191 the induction variable. Used to ensure that only the last insn modifying
192 a split iv will update the original iv of the dest. */
194 static int *splittable_regs_updates;
196 /* Forward declarations. */
198 static void init_reg_map PARAMS ((struct inline_remap *, int));
199 static rtx calculate_giv_inc PARAMS ((rtx, rtx, int));
200 static rtx initial_reg_note_copy PARAMS ((rtx, struct inline_remap *));
201 static void final_reg_note_copy PARAMS ((rtx, struct inline_remap *));
202 static void copy_loop_body PARAMS ((rtx, rtx, struct inline_remap *, rtx, int,
203 enum unroll_types, rtx, rtx, rtx, rtx));
204 static void iteration_info PARAMS ((const struct loop *, rtx, rtx *, rtx *));
205 static int find_splittable_regs PARAMS ((const struct loop *,
206 enum unroll_types, rtx, int));
207 static int find_splittable_givs PARAMS ((const struct loop *,
208 struct iv_class *, enum unroll_types,
210 static int reg_dead_after_loop PARAMS ((const struct loop *, rtx));
211 static rtx fold_rtx_mult_add PARAMS ((rtx, rtx, rtx, enum machine_mode));
212 static int verify_addresses PARAMS ((struct induction *, rtx, int));
213 static rtx remap_split_bivs PARAMS ((rtx));
214 static rtx find_common_reg_term PARAMS ((rtx, rtx));
215 static rtx subtract_reg_term PARAMS ((rtx, rtx));
216 static rtx loop_find_equiv_value PARAMS ((const struct loop *, rtx));
218 /* Try to unroll one loop and split induction variables in the loop.
220 The loop is described by the arguments LOOP and INSN_COUNT.
221 END_INSERT_BEFORE indicates where insns should be added which need
222 to be executed when the loop falls through. STRENGTH_REDUCTION_P
223 indicates whether information generated in the strength reduction
226 This function is intended to be called from within `strength_reduce'
230 unroll_loop (loop, insn_count, end_insert_before, strength_reduce_p)
233 rtx end_insert_before;
234 int strength_reduce_p;
237 unsigned HOST_WIDE_INT temp;
238 int unroll_number = 1;
239 rtx copy_start, copy_end;
240 rtx insn, sequence, pattern, tem;
241 int max_labelno, max_insnno;
243 struct inline_remap *map;
244 char *local_label = NULL;
246 int max_local_regnum;
251 int splitting_not_safe = 0;
252 enum unroll_types unroll_type = UNROLL_NAIVE;
253 int loop_preconditioned = 0;
255 /* This points to the last real insn in the loop, which should be either
256 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
259 rtx loop_start = loop->start;
260 rtx loop_end = loop->end;
261 struct loop_info *loop_info = LOOP_INFO (loop);
263 /* Don't bother unrolling huge loops. Since the minimum factor is
264 two, loops greater than one half of MAX_UNROLLED_INSNS will never
266 if (insn_count > MAX_UNROLLED_INSNS / 2)
268 if (loop_dump_stream)
269 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
273 /* When emitting debugger info, we can't unroll loops with unequal numbers
274 of block_beg and block_end notes, because that would unbalance the block
275 structure of the function. This can happen as a result of the
276 "if (foo) bar; else break;" optimization in jump.c. */
277 /* ??? Gcc has a general policy that -g is never supposed to change the code
278 that the compiler emits, so we must disable this optimization always,
279 even if debug info is not being output. This is rare, so this should
280 not be a significant performance problem. */
282 if (1 /* write_symbols != NO_DEBUG */)
284 int block_begins = 0;
287 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
289 if (GET_CODE (insn) == NOTE)
291 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
293 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
295 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG
296 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
298 /* Note, would be nice to add code to unroll EH
299 regions, but until that time, we punt (don't
300 unroll). For the proper way of doing it, see
301 expand_inline_function. */
303 if (loop_dump_stream)
304 fprintf (loop_dump_stream,
305 "Unrolling failure: cannot unroll EH regions.\n");
311 if (block_begins != block_ends)
313 if (loop_dump_stream)
314 fprintf (loop_dump_stream,
315 "Unrolling failure: Unbalanced block notes.\n");
320 /* Determine type of unroll to perform. Depends on the number of iterations
321 and the size of the loop. */
323 /* If there is no strength reduce info, then set
324 loop_info->n_iterations to zero. This can happen if
325 strength_reduce can't find any bivs in the loop. A value of zero
326 indicates that the number of iterations could not be calculated. */
328 if (! strength_reduce_p)
329 loop_info->n_iterations = 0;
331 if (loop_dump_stream && loop_info->n_iterations > 0)
333 fputs ("Loop unrolling: ", loop_dump_stream);
334 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
335 loop_info->n_iterations);
336 fputs (" iterations.\n", loop_dump_stream);
339 /* Find and save a pointer to the last nonnote insn in the loop. */
341 last_loop_insn = prev_nonnote_insn (loop_end);
343 /* Calculate how many times to unroll the loop. Indicate whether or
344 not the loop is being completely unrolled. */
346 if (loop_info->n_iterations == 1)
348 /* If number of iterations is exactly 1, then eliminate the compare and
349 branch at the end of the loop since they will never be taken.
350 Then return, since no other action is needed here. */
352 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
353 don't do anything. */
355 if (GET_CODE (last_loop_insn) == BARRIER)
357 /* Delete the jump insn. This will delete the barrier also. */
358 delete_insn (PREV_INSN (last_loop_insn));
360 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
363 rtx prev = PREV_INSN (last_loop_insn);
365 delete_insn (last_loop_insn);
367 /* The immediately preceding insn may be a compare which must be
369 if (sets_cc0_p (prev))
374 /* Remove the loop notes since this is no longer a loop. */
376 delete_insn (loop->vtop);
378 delete_insn (loop->cont);
380 delete_insn (loop_start);
382 delete_insn (loop_end);
386 else if (loop_info->n_iterations > 0
387 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
389 unroll_number = loop_info->n_iterations;
390 unroll_type = UNROLL_COMPLETELY;
392 else if (loop_info->n_iterations > 0)
394 /* Try to factor the number of iterations. Don't bother with the
395 general case, only using 2, 3, 5, and 7 will get 75% of all
396 numbers theoretically, and almost all in practice. */
398 for (i = 0; i < NUM_FACTORS; i++)
399 factors[i].count = 0;
401 temp = loop_info->n_iterations;
402 for (i = NUM_FACTORS - 1; i >= 0; i--)
403 while (temp % factors[i].factor == 0)
406 temp = temp / factors[i].factor;
409 /* Start with the larger factors first so that we generally
410 get lots of unrolling. */
414 for (i = 3; i >= 0; i--)
415 while (factors[i].count--)
417 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
419 unroll_number *= factors[i].factor;
420 temp *= factors[i].factor;
426 /* If we couldn't find any factors, then unroll as in the normal
428 if (unroll_number == 1)
430 if (loop_dump_stream)
431 fprintf (loop_dump_stream,
432 "Loop unrolling: No factors found.\n");
435 unroll_type = UNROLL_MODULO;
439 /* Default case, calculate number of times to unroll loop based on its
441 if (unroll_type == UNROLL_NAIVE)
443 if (8 * insn_count < MAX_UNROLLED_INSNS)
445 else if (4 * insn_count < MAX_UNROLLED_INSNS)
451 /* Now we know how many times to unroll the loop. */
453 if (loop_dump_stream)
454 fprintf (loop_dump_stream,
455 "Unrolling loop %d times.\n", unroll_number);
458 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
460 /* Loops of these types can start with jump down to the exit condition
461 in rare circumstances.
463 Consider a pair of nested loops where the inner loop is part
464 of the exit code for the outer loop.
466 In this case jump.c will not duplicate the exit test for the outer
467 loop, so it will start with a jump to the exit code.
469 Then consider if the inner loop turns out to iterate once and
470 only once. We will end up deleting the jumps associated with
471 the inner loop. However, the loop notes are not removed from
472 the instruction stream.
474 And finally assume that we can compute the number of iterations
477 In this case unroll may want to unroll the outer loop even though
478 it starts with a jump to the outer loop's exit code.
480 We could try to optimize this case, but it hardly seems worth it.
481 Just return without unrolling the loop in such cases. */
484 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
485 insn = NEXT_INSN (insn);
486 if (GET_CODE (insn) == JUMP_INSN)
490 if (unroll_type == UNROLL_COMPLETELY)
492 /* Completely unrolling the loop: Delete the compare and branch at
493 the end (the last two instructions). This delete must done at the
494 very end of loop unrolling, to avoid problems with calls to
495 back_branch_in_range_p, which is called by find_splittable_regs.
496 All increments of splittable bivs/givs are changed to load constant
499 copy_start = loop_start;
501 /* Set insert_before to the instruction immediately after the JUMP_INSN
502 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
503 the loop will be correctly handled by copy_loop_body. */
504 insert_before = NEXT_INSN (last_loop_insn);
506 /* Set copy_end to the insn before the jump at the end of the loop. */
507 if (GET_CODE (last_loop_insn) == BARRIER)
508 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
509 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
511 copy_end = PREV_INSN (last_loop_insn);
513 /* The instruction immediately before the JUMP_INSN may be a compare
514 instruction which we do not want to copy. */
515 if (sets_cc0_p (PREV_INSN (copy_end)))
516 copy_end = PREV_INSN (copy_end);
521 /* We currently can't unroll a loop if it doesn't end with a
522 JUMP_INSN. There would need to be a mechanism that recognizes
523 this case, and then inserts a jump after each loop body, which
524 jumps to after the last loop body. */
525 if (loop_dump_stream)
526 fprintf (loop_dump_stream,
527 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
531 else if (unroll_type == UNROLL_MODULO)
533 /* Partially unrolling the loop: The compare and branch at the end
534 (the last two instructions) must remain. Don't copy the compare
535 and branch instructions at the end of the loop. Insert the unrolled
536 code immediately before the compare/branch at the end so that the
537 code will fall through to them as before. */
539 copy_start = loop_start;
541 /* Set insert_before to the jump insn at the end of the loop.
542 Set copy_end to before the jump insn at the end of the loop. */
543 if (GET_CODE (last_loop_insn) == BARRIER)
545 insert_before = PREV_INSN (last_loop_insn);
546 copy_end = PREV_INSN (insert_before);
548 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
550 insert_before = last_loop_insn;
552 /* The instruction immediately before the JUMP_INSN may be a compare
553 instruction which we do not want to copy or delete. */
554 if (sets_cc0_p (PREV_INSN (insert_before)))
555 insert_before = PREV_INSN (insert_before);
557 copy_end = PREV_INSN (insert_before);
561 /* We currently can't unroll a loop if it doesn't end with a
562 JUMP_INSN. There would need to be a mechanism that recognizes
563 this case, and then inserts a jump after each loop body, which
564 jumps to after the last loop body. */
565 if (loop_dump_stream)
566 fprintf (loop_dump_stream,
567 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
573 /* Normal case: Must copy the compare and branch instructions at the
576 if (GET_CODE (last_loop_insn) == BARRIER)
578 /* Loop ends with an unconditional jump and a barrier.
579 Handle this like above, don't copy jump and barrier.
580 This is not strictly necessary, but doing so prevents generating
581 unconditional jumps to an immediately following label.
583 This will be corrected below if the target of this jump is
584 not the start_label. */
586 insert_before = PREV_INSN (last_loop_insn);
587 copy_end = PREV_INSN (insert_before);
589 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
591 /* Set insert_before to immediately after the JUMP_INSN, so that
592 NOTEs at the end of the loop will be correctly handled by
594 insert_before = NEXT_INSN (last_loop_insn);
595 copy_end = last_loop_insn;
599 /* We currently can't unroll a loop if it doesn't end with a
600 JUMP_INSN. There would need to be a mechanism that recognizes
601 this case, and then inserts a jump after each loop body, which
602 jumps to after the last loop body. */
603 if (loop_dump_stream)
604 fprintf (loop_dump_stream,
605 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
609 /* If copying exit test branches because they can not be eliminated,
610 then must convert the fall through case of the branch to a jump past
611 the end of the loop. Create a label to emit after the loop and save
612 it for later use. Do not use the label after the loop, if any, since
613 it might be used by insns outside the loop, or there might be insns
614 added before it later by final_[bg]iv_value which must be after
615 the real exit label. */
616 exit_label = gen_label_rtx ();
619 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
620 insn = NEXT_INSN (insn);
622 if (GET_CODE (insn) == JUMP_INSN)
624 /* The loop starts with a jump down to the exit condition test.
625 Start copying the loop after the barrier following this
627 copy_start = NEXT_INSN (insn);
629 /* Splitting induction variables doesn't work when the loop is
630 entered via a jump to the bottom, because then we end up doing
631 a comparison against a new register for a split variable, but
632 we did not execute the set insn for the new register because
633 it was skipped over. */
634 splitting_not_safe = 1;
635 if (loop_dump_stream)
636 fprintf (loop_dump_stream,
637 "Splitting not safe, because loop not entered at top.\n");
640 copy_start = loop_start;
643 /* This should always be the first label in the loop. */
644 start_label = NEXT_INSN (copy_start);
645 /* There may be a line number note and/or a loop continue note here. */
646 while (GET_CODE (start_label) == NOTE)
647 start_label = NEXT_INSN (start_label);
648 if (GET_CODE (start_label) != CODE_LABEL)
650 /* This can happen as a result of jump threading. If the first insns in
651 the loop test the same condition as the loop's backward jump, or the
652 opposite condition, then the backward jump will be modified to point
653 to elsewhere, and the loop's start label is deleted.
655 This case currently can not be handled by the loop unrolling code. */
657 if (loop_dump_stream)
658 fprintf (loop_dump_stream,
659 "Unrolling failure: unknown insns between BEG note and loop label.\n");
662 if (LABEL_NAME (start_label))
664 /* The jump optimization pass must have combined the original start label
665 with a named label for a goto. We can't unroll this case because
666 jumps which go to the named label must be handled differently than
667 jumps to the loop start, and it is impossible to differentiate them
669 if (loop_dump_stream)
670 fprintf (loop_dump_stream,
671 "Unrolling failure: loop start label is gone\n");
675 if (unroll_type == UNROLL_NAIVE
676 && GET_CODE (last_loop_insn) == BARRIER
677 && GET_CODE (PREV_INSN (last_loop_insn)) == JUMP_INSN
678 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
680 /* In this case, we must copy the jump and barrier, because they will
681 not be converted to jumps to an immediately following label. */
683 insert_before = NEXT_INSN (last_loop_insn);
684 copy_end = last_loop_insn;
687 if (unroll_type == UNROLL_NAIVE
688 && GET_CODE (last_loop_insn) == JUMP_INSN
689 && start_label != JUMP_LABEL (last_loop_insn))
691 /* ??? The loop ends with a conditional branch that does not branch back
692 to the loop start label. In this case, we must emit an unconditional
693 branch to the loop exit after emitting the final branch.
694 copy_loop_body does not have support for this currently, so we
695 give up. It doesn't seem worthwhile to unroll anyways since
696 unrolling would increase the number of branch instructions
698 if (loop_dump_stream)
699 fprintf (loop_dump_stream,
700 "Unrolling failure: final conditional branch not to loop start\n");
704 /* Allocate a translation table for the labels and insn numbers.
705 They will be filled in as we copy the insns in the loop. */
707 max_labelno = max_label_num ();
708 max_insnno = get_max_uid ();
710 /* Various paths through the unroll code may reach the "egress" label
711 without initializing fields within the map structure.
713 To be safe, we use xcalloc to zero the memory. */
714 map = (struct inline_remap *) xcalloc (1, sizeof (struct inline_remap));
716 /* Allocate the label map. */
720 map->label_map = (rtx *) xmalloc (max_labelno * sizeof (rtx));
722 local_label = (char *) xcalloc (max_labelno, sizeof (char));
725 /* Search the loop and mark all local labels, i.e. the ones which have to
726 be distinct labels when copied. For all labels which might be
727 non-local, set their label_map entries to point to themselves.
728 If they happen to be local their label_map entries will be overwritten
729 before the loop body is copied. The label_map entries for local labels
730 will be set to a different value each time the loop body is copied. */
732 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
736 if (GET_CODE (insn) == CODE_LABEL)
737 local_label[CODE_LABEL_NUMBER (insn)] = 1;
738 else if (GET_CODE (insn) == JUMP_INSN)
740 if (JUMP_LABEL (insn))
741 set_label_in_map (map,
742 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
744 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
745 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
747 rtx pat = PATTERN (insn);
748 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
749 int len = XVECLEN (pat, diff_vec_p);
752 for (i = 0; i < len; i++)
754 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
755 set_label_in_map (map,
756 CODE_LABEL_NUMBER (label),
761 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
762 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
766 /* Allocate space for the insn map. */
768 map->insn_map = (rtx *) xmalloc (max_insnno * sizeof (rtx));
770 /* Set this to zero, to indicate that we are doing loop unrolling,
771 not function inlining. */
772 map->inline_target = 0;
774 /* The register and constant maps depend on the number of registers
775 present, so the final maps can't be created until after
776 find_splittable_regs is called. However, they are needed for
777 preconditioning, so we create temporary maps when preconditioning
780 /* The preconditioning code may allocate two new pseudo registers. */
781 maxregnum = max_reg_num ();
783 /* local_regno is only valid for regnos < max_local_regnum. */
784 max_local_regnum = maxregnum;
786 /* Allocate and zero out the splittable_regs and addr_combined_regs
787 arrays. These must be zeroed here because they will be used if
788 loop preconditioning is performed, and must be zero for that case.
790 It is safe to do this here, since the extra registers created by the
791 preconditioning code and find_splittable_regs will never be used
792 to access the splittable_regs[] and addr_combined_regs[] arrays. */
794 splittable_regs = (rtx *) xcalloc (maxregnum, sizeof (rtx));
795 derived_regs = (char *) xcalloc (maxregnum, sizeof (char));
796 splittable_regs_updates = (int *) xcalloc (maxregnum, sizeof (int));
798 = (struct induction **) xcalloc (maxregnum, sizeof (struct induction *));
799 local_regno = (char *) xcalloc (maxregnum, sizeof (char));
801 /* Mark all local registers, i.e. the ones which are referenced only
803 if (INSN_UID (copy_end) < max_uid_for_loop)
805 int copy_start_luid = INSN_LUID (copy_start);
806 int copy_end_luid = INSN_LUID (copy_end);
808 /* If a register is used in the jump insn, we must not duplicate it
809 since it will also be used outside the loop. */
810 if (GET_CODE (copy_end) == JUMP_INSN)
813 /* If we have a target that uses cc0, then we also must not duplicate
814 the insn that sets cc0 before the jump insn, if one is present. */
816 if (GET_CODE (copy_end) == JUMP_INSN && sets_cc0_p (PREV_INSN (copy_end)))
820 /* If copy_start points to the NOTE that starts the loop, then we must
821 use the next luid, because invariant pseudo-regs moved out of the loop
822 have their lifetimes modified to start here, but they are not safe
824 if (copy_start == loop_start)
827 /* If a pseudo's lifetime is entirely contained within this loop, then we
828 can use a different pseudo in each unrolled copy of the loop. This
829 results in better code. */
830 /* We must limit the generic test to max_reg_before_loop, because only
831 these pseudo registers have valid regno_first_uid info. */
832 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
833 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
834 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
835 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
836 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
838 /* However, we must also check for loop-carried dependencies.
839 If the value the pseudo has at the end of iteration X is
840 used by iteration X+1, then we can not use a different pseudo
841 for each unrolled copy of the loop. */
842 /* A pseudo is safe if regno_first_uid is a set, and this
843 set dominates all instructions from regno_first_uid to
845 /* ??? This check is simplistic. We would get better code if
846 this check was more sophisticated. */
847 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
848 copy_start, copy_end))
851 if (loop_dump_stream)
854 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
856 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
860 /* Givs that have been created from multiple biv increments always have
862 for (j = first_increment_giv; j <= last_increment_giv; j++)
865 if (loop_dump_stream)
866 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
870 /* If this loop requires exit tests when unrolled, check to see if we
871 can precondition the loop so as to make the exit tests unnecessary.
872 Just like variable splitting, this is not safe if the loop is entered
873 via a jump to the bottom. Also, can not do this if no strength
874 reduce info, because precondition_loop_p uses this info. */
876 /* Must copy the loop body for preconditioning before the following
877 find_splittable_regs call since that will emit insns which need to
878 be after the preconditioned loop copies, but immediately before the
879 unrolled loop copies. */
881 /* Also, it is not safe to split induction variables for the preconditioned
882 copies of the loop body. If we split induction variables, then the code
883 assumes that each induction variable can be represented as a function
884 of its initial value and the loop iteration number. This is not true
885 in this case, because the last preconditioned copy of the loop body
886 could be any iteration from the first up to the `unroll_number-1'th,
887 depending on the initial value of the iteration variable. Therefore
888 we can not split induction variables here, because we can not calculate
889 their value. Hence, this code must occur before find_splittable_regs
892 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
894 rtx initial_value, final_value, increment;
895 enum machine_mode mode;
897 if (precondition_loop_p (loop,
898 &initial_value, &final_value, &increment,
903 int abs_inc, neg_inc;
905 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
907 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
909 global_const_equiv_varray = map->const_equiv_varray;
911 init_reg_map (map, maxregnum);
913 /* Limit loop unrolling to 4, since this will make 7 copies of
915 if (unroll_number > 4)
918 /* Save the absolute value of the increment, and also whether or
919 not it is negative. */
921 abs_inc = INTVAL (increment);
930 /* Calculate the difference between the final and initial values.
931 Final value may be a (plus (reg x) (const_int 1)) rtx.
932 Let the following cse pass simplify this if initial value is
935 We must copy the final and initial values here to avoid
936 improperly shared rtl. */
938 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
939 copy_rtx (initial_value), NULL_RTX, 0,
942 /* Now calculate (diff % (unroll * abs (increment))) by using an
944 diff = expand_binop (GET_MODE (diff), and_optab, diff,
945 GEN_INT (unroll_number * abs_inc - 1),
946 NULL_RTX, 0, OPTAB_LIB_WIDEN);
948 /* Now emit a sequence of branches to jump to the proper precond
951 labels = (rtx *) xmalloc (sizeof (rtx) * unroll_number);
952 for (i = 0; i < unroll_number; i++)
953 labels[i] = gen_label_rtx ();
955 /* Check for the case where the initial value is greater than or
956 equal to the final value. In that case, we want to execute
957 exactly one loop iteration. The code below will fail for this
958 case. This check does not apply if the loop has a NE
959 comparison at the end. */
961 if (loop_info->comparison_code != NE)
963 emit_cmp_and_jump_insns (initial_value, final_value,
965 NULL_RTX, mode, 0, 0, labels[1]);
966 JUMP_LABEL (get_last_insn ()) = labels[1];
967 LABEL_NUSES (labels[1])++;
970 /* Assuming the unroll_number is 4, and the increment is 2, then
971 for a negative increment: for a positive increment:
972 diff = 0,1 precond 0 diff = 0,7 precond 0
973 diff = 2,3 precond 3 diff = 1,2 precond 1
974 diff = 4,5 precond 2 diff = 3,4 precond 2
975 diff = 6,7 precond 1 diff = 5,6 precond 3 */
977 /* We only need to emit (unroll_number - 1) branches here, the
978 last case just falls through to the following code. */
980 /* ??? This would give better code if we emitted a tree of branches
981 instead of the current linear list of branches. */
983 for (i = 0; i < unroll_number - 1; i++)
986 enum rtx_code cmp_code;
988 /* For negative increments, must invert the constant compared
989 against, except when comparing against zero. */
997 cmp_const = unroll_number - i;
1006 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
1007 cmp_code, NULL_RTX, mode, 0, 0,
1009 JUMP_LABEL (get_last_insn ()) = labels[i];
1010 LABEL_NUSES (labels[i])++;
1013 /* If the increment is greater than one, then we need another branch,
1014 to handle other cases equivalent to 0. */
1016 /* ??? This should be merged into the code above somehow to help
1017 simplify the code here, and reduce the number of branches emitted.
1018 For the negative increment case, the branch here could easily
1019 be merged with the `0' case branch above. For the positive
1020 increment case, it is not clear how this can be simplified. */
1025 enum rtx_code cmp_code;
1029 cmp_const = abs_inc - 1;
1034 cmp_const = abs_inc * (unroll_number - 1) + 1;
1038 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1039 NULL_RTX, mode, 0, 0, labels[0]);
1040 JUMP_LABEL (get_last_insn ()) = labels[0];
1041 LABEL_NUSES (labels[0])++;
1044 sequence = gen_sequence ();
1046 emit_insn_before (sequence, loop_start);
1048 /* Only the last copy of the loop body here needs the exit
1049 test, so set copy_end to exclude the compare/branch here,
1050 and then reset it inside the loop when get to the last
1053 if (GET_CODE (last_loop_insn) == BARRIER)
1054 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1055 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1057 copy_end = PREV_INSN (last_loop_insn);
1059 /* The immediately preceding insn may be a compare which we do not
1061 if (sets_cc0_p (PREV_INSN (copy_end)))
1062 copy_end = PREV_INSN (copy_end);
1068 for (i = 1; i < unroll_number; i++)
1070 emit_label_after (labels[unroll_number - i],
1071 PREV_INSN (loop_start));
1073 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1074 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1075 (VARRAY_SIZE (map->const_equiv_varray)
1076 * sizeof (struct const_equiv_data)));
1079 for (j = 0; j < max_labelno; j++)
1081 set_label_in_map (map, j, gen_label_rtx ());
1083 for (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
1086 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1087 record_base_value (REGNO (map->reg_map[j]),
1088 regno_reg_rtx[j], 0);
1090 /* The last copy needs the compare/branch insns at the end,
1091 so reset copy_end here if the loop ends with a conditional
1094 if (i == unroll_number - 1)
1096 if (GET_CODE (last_loop_insn) == BARRIER)
1097 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1099 copy_end = last_loop_insn;
1102 /* None of the copies are the `last_iteration', so just
1103 pass zero for that parameter. */
1104 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1105 unroll_type, start_label, loop_end,
1106 loop_start, copy_end);
1108 emit_label_after (labels[0], PREV_INSN (loop_start));
1110 if (GET_CODE (last_loop_insn) == BARRIER)
1112 insert_before = PREV_INSN (last_loop_insn);
1113 copy_end = PREV_INSN (insert_before);
1117 insert_before = last_loop_insn;
1119 /* The instruction immediately before the JUMP_INSN may be a compare
1120 instruction which we do not want to copy or delete. */
1121 if (sets_cc0_p (PREV_INSN (insert_before)))
1122 insert_before = PREV_INSN (insert_before);
1124 copy_end = PREV_INSN (insert_before);
1127 /* Set unroll type to MODULO now. */
1128 unroll_type = UNROLL_MODULO;
1129 loop_preconditioned = 1;
1136 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1137 the loop unless all loops are being unrolled. */
1138 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1140 if (loop_dump_stream)
1141 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1145 /* At this point, we are guaranteed to unroll the loop. */
1147 /* Keep track of the unroll factor for the loop. */
1148 loop_info->unroll_number = unroll_number;
1150 /* For each biv and giv, determine whether it can be safely split into
1151 a different variable for each unrolled copy of the loop body.
1152 We precalculate and save this info here, since computing it is
1155 Do this before deleting any instructions from the loop, so that
1156 back_branch_in_range_p will work correctly. */
1158 if (splitting_not_safe)
1161 temp = find_splittable_regs (loop, unroll_type,
1162 end_insert_before, unroll_number);
1164 /* find_splittable_regs may have created some new registers, so must
1165 reallocate the reg_map with the new larger size, and must realloc
1166 the constant maps also. */
1168 maxregnum = max_reg_num ();
1169 map->reg_map = (rtx *) xmalloc (maxregnum * sizeof (rtx));
1171 init_reg_map (map, maxregnum);
1173 if (map->const_equiv_varray == 0)
1174 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1175 maxregnum + temp * unroll_number * 2,
1177 global_const_equiv_varray = map->const_equiv_varray;
1179 /* Search the list of bivs and givs to find ones which need to be remapped
1180 when split, and set their reg_map entry appropriately. */
1182 for (bl = loop_iv_list; bl; bl = bl->next)
1184 if (REGNO (bl->biv->src_reg) != bl->regno)
1185 map->reg_map[bl->regno] = bl->biv->src_reg;
1187 /* Currently, non-reduced/final-value givs are never split. */
1188 for (v = bl->giv; v; v = v->next_iv)
1189 if (REGNO (v->src_reg) != bl->regno)
1190 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1194 /* Use our current register alignment and pointer flags. */
1195 map->regno_pointer_flag = cfun->emit->regno_pointer_flag;
1196 map->regno_pointer_align = cfun->emit->regno_pointer_align;
1198 /* If the loop is being partially unrolled, and the iteration variables
1199 are being split, and are being renamed for the split, then must fix up
1200 the compare/jump instruction at the end of the loop to refer to the new
1201 registers. This compare isn't copied, so the registers used in it
1202 will never be replaced if it isn't done here. */
1204 if (unroll_type == UNROLL_MODULO)
1206 insn = NEXT_INSN (copy_end);
1207 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1208 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1211 /* For unroll_number times, make a copy of each instruction
1212 between copy_start and copy_end, and insert these new instructions
1213 before the end of the loop. */
1215 for (i = 0; i < unroll_number; i++)
1217 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1218 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1219 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1222 for (j = 0; j < max_labelno; j++)
1224 set_label_in_map (map, j, gen_label_rtx ());
1226 for (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
1229 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1230 record_base_value (REGNO (map->reg_map[j]),
1231 regno_reg_rtx[j], 0);
1234 /* If loop starts with a branch to the test, then fix it so that
1235 it points to the test of the first unrolled copy of the loop. */
1236 if (i == 0 && loop_start != copy_start)
1238 insn = PREV_INSN (copy_start);
1239 pattern = PATTERN (insn);
1241 tem = get_label_from_map (map,
1243 (XEXP (SET_SRC (pattern), 0)));
1244 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1246 /* Set the jump label so that it can be used by later loop unrolling
1248 JUMP_LABEL (insn) = tem;
1249 LABEL_NUSES (tem)++;
1252 copy_loop_body (copy_start, copy_end, map, exit_label,
1253 i == unroll_number - 1, unroll_type, start_label,
1254 loop_end, insert_before, insert_before);
1257 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1258 insn to be deleted. This prevents any runaway delete_insn call from
1259 more insns that it should, as it always stops at a CODE_LABEL. */
1261 /* Delete the compare and branch at the end of the loop if completely
1262 unrolling the loop. Deleting the backward branch at the end also
1263 deletes the code label at the start of the loop. This is done at
1264 the very end to avoid problems with back_branch_in_range_p. */
1266 if (unroll_type == UNROLL_COMPLETELY)
1267 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1269 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1271 /* Delete all of the original loop instructions. Don't delete the
1272 LOOP_BEG note, or the first code label in the loop. */
1274 insn = NEXT_INSN (copy_start);
1275 while (insn != safety_label)
1277 /* ??? Don't delete named code labels. They will be deleted when the
1278 jump that references them is deleted. Otherwise, we end up deleting
1279 them twice, which causes them to completely disappear instead of turn
1280 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1281 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1282 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1283 associated LABEL_DECL to point to one of the new label instances. */
1284 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1285 if (insn != start_label
1286 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1287 && ! (GET_CODE (insn) == NOTE
1288 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1289 insn = delete_insn (insn);
1291 insn = NEXT_INSN (insn);
1294 /* Can now delete the 'safety' label emitted to protect us from runaway
1295 delete_insn calls. */
1296 if (INSN_DELETED_P (safety_label))
1298 delete_insn (safety_label);
1300 /* If exit_label exists, emit it after the loop. Doing the emit here
1301 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1302 This is needed so that mostly_true_jump in reorg.c will treat jumps
1303 to this loop end label correctly, i.e. predict that they are usually
1306 emit_label_after (exit_label, loop_end);
1309 if (unroll_type == UNROLL_COMPLETELY)
1311 /* Remove the loop notes since this is no longer a loop. */
1313 delete_insn (loop->vtop);
1315 delete_insn (loop->cont);
1317 delete_insn (loop_start);
1319 delete_insn (loop_end);
1322 if (map->const_equiv_varray)
1323 VARRAY_FREE (map->const_equiv_varray);
1326 free (map->label_map);
1329 free (map->insn_map);
1330 free (splittable_regs);
1331 free (derived_regs);
1332 free (splittable_regs_updates);
1333 free (addr_combined_regs);
1336 free (map->reg_map);
1340 /* Return true if the loop can be safely, and profitably, preconditioned
1341 so that the unrolled copies of the loop body don't need exit tests.
1343 This only works if final_value, initial_value and increment can be
1344 determined, and if increment is a constant power of 2.
1345 If increment is not a power of 2, then the preconditioning modulo
1346 operation would require a real modulo instead of a boolean AND, and this
1347 is not considered `profitable'. */
1349 /* ??? If the loop is known to be executed very many times, or the machine
1350 has a very cheap divide instruction, then preconditioning is a win even
1351 when the increment is not a power of 2. Use RTX_COST to compute
1352 whether divide is cheap.
1353 ??? A divide by constant doesn't actually need a divide, look at
1354 expand_divmod. The reduced cost of this optimized modulo is not
1355 reflected in RTX_COST. */
1358 precondition_loop_p (loop, initial_value, final_value, increment, mode)
1359 const struct loop *loop;
1360 rtx *initial_value, *final_value, *increment;
1361 enum machine_mode *mode;
1363 rtx loop_start = loop->start;
1364 struct loop_info *loop_info = LOOP_INFO (loop);
1366 if (loop_info->n_iterations > 0)
1368 *initial_value = const0_rtx;
1369 *increment = const1_rtx;
1370 *final_value = GEN_INT (loop_info->n_iterations);
1373 if (loop_dump_stream)
1375 fputs ("Preconditioning: Success, number of iterations known, ",
1377 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1378 loop_info->n_iterations);
1379 fputs (".\n", loop_dump_stream);
1384 if (loop_info->initial_value == 0)
1386 if (loop_dump_stream)
1387 fprintf (loop_dump_stream,
1388 "Preconditioning: Could not find initial value.\n");
1391 else if (loop_info->increment == 0)
1393 if (loop_dump_stream)
1394 fprintf (loop_dump_stream,
1395 "Preconditioning: Could not find increment value.\n");
1398 else if (GET_CODE (loop_info->increment) != CONST_INT)
1400 if (loop_dump_stream)
1401 fprintf (loop_dump_stream,
1402 "Preconditioning: Increment not a constant.\n");
1405 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1406 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1408 if (loop_dump_stream)
1409 fprintf (loop_dump_stream,
1410 "Preconditioning: Increment not a constant power of 2.\n");
1414 /* Unsigned_compare and compare_dir can be ignored here, since they do
1415 not matter for preconditioning. */
1417 if (loop_info->final_value == 0)
1419 if (loop_dump_stream)
1420 fprintf (loop_dump_stream,
1421 "Preconditioning: EQ comparison loop.\n");
1425 /* Must ensure that final_value is invariant, so call
1426 loop_invariant_p to check. Before doing so, must check regno
1427 against max_reg_before_loop to make sure that the register is in
1428 the range covered by loop_invariant_p. If it isn't, then it is
1429 most likely a biv/giv which by definition are not invariant. */
1430 if ((GET_CODE (loop_info->final_value) == REG
1431 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1432 || (GET_CODE (loop_info->final_value) == PLUS
1433 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1434 || ! loop_invariant_p (loop, loop_info->final_value))
1436 if (loop_dump_stream)
1437 fprintf (loop_dump_stream,
1438 "Preconditioning: Final value not invariant.\n");
1442 /* Fail for floating point values, since the caller of this function
1443 does not have code to deal with them. */
1444 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1445 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1447 if (loop_dump_stream)
1448 fprintf (loop_dump_stream,
1449 "Preconditioning: Floating point final or initial value.\n");
1453 /* Fail if loop_info->iteration_var is not live before loop_start,
1454 since we need to test its value in the preconditioning code. */
1456 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1457 > INSN_LUID (loop_start))
1459 if (loop_dump_stream)
1460 fprintf (loop_dump_stream,
1461 "Preconditioning: Iteration var not live before loop start.\n");
1465 /* Note that iteration_info biases the initial value for GIV iterators
1466 such as "while (i-- > 0)" so that we can calculate the number of
1467 iterations just like for BIV iterators.
1469 Also note that the absolute values of initial_value and
1470 final_value are unimportant as only their difference is used for
1471 calculating the number of loop iterations. */
1472 *initial_value = loop_info->initial_value;
1473 *increment = loop_info->increment;
1474 *final_value = loop_info->final_value;
1476 /* Decide what mode to do these calculations in. Choose the larger
1477 of final_value's mode and initial_value's mode, or a full-word if
1478 both are constants. */
1479 *mode = GET_MODE (*final_value);
1480 if (*mode == VOIDmode)
1482 *mode = GET_MODE (*initial_value);
1483 if (*mode == VOIDmode)
1486 else if (*mode != GET_MODE (*initial_value)
1487 && (GET_MODE_SIZE (*mode)
1488 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1489 *mode = GET_MODE (*initial_value);
1492 if (loop_dump_stream)
1493 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1498 /* All pseudo-registers must be mapped to themselves. Two hard registers
1499 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1500 REGNUM, to avoid function-inlining specific conversions of these
1501 registers. All other hard regs can not be mapped because they may be
1506 init_reg_map (map, maxregnum)
1507 struct inline_remap *map;
1512 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1513 map->reg_map[i] = regno_reg_rtx[i];
1514 /* Just clear the rest of the entries. */
1515 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1516 map->reg_map[i] = 0;
1518 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1519 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1520 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1521 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1524 /* Strength-reduction will often emit code for optimized biv/givs which
1525 calculates their value in a temporary register, and then copies the result
1526 to the iv. This procedure reconstructs the pattern computing the iv;
1527 verifying that all operands are of the proper form.
1529 PATTERN must be the result of single_set.
1530 The return value is the amount that the giv is incremented by. */
1533 calculate_giv_inc (pattern, src_insn, regno)
1534 rtx pattern, src_insn;
1538 rtx increment_total = 0;
1542 /* Verify that we have an increment insn here. First check for a plus
1543 as the set source. */
1544 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1546 /* SR sometimes computes the new giv value in a temp, then copies it
1548 src_insn = PREV_INSN (src_insn);
1549 pattern = PATTERN (src_insn);
1550 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1553 /* The last insn emitted is not needed, so delete it to avoid confusing
1554 the second cse pass. This insn sets the giv unnecessarily. */
1555 delete_insn (get_last_insn ());
1558 /* Verify that we have a constant as the second operand of the plus. */
1559 increment = XEXP (SET_SRC (pattern), 1);
1560 if (GET_CODE (increment) != CONST_INT)
1562 /* SR sometimes puts the constant in a register, especially if it is
1563 too big to be an add immed operand. */
1564 src_insn = PREV_INSN (src_insn);
1565 increment = SET_SRC (PATTERN (src_insn));
1567 /* SR may have used LO_SUM to compute the constant if it is too large
1568 for a load immed operand. In this case, the constant is in operand
1569 one of the LO_SUM rtx. */
1570 if (GET_CODE (increment) == LO_SUM)
1571 increment = XEXP (increment, 1);
1573 /* Some ports store large constants in memory and add a REG_EQUAL
1574 note to the store insn. */
1575 else if (GET_CODE (increment) == MEM)
1577 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1579 increment = XEXP (note, 0);
1582 else if (GET_CODE (increment) == IOR
1583 || GET_CODE (increment) == ASHIFT
1584 || GET_CODE (increment) == PLUS)
1586 /* The rs6000 port loads some constants with IOR.
1587 The alpha port loads some constants with ASHIFT and PLUS. */
1588 rtx second_part = XEXP (increment, 1);
1589 enum rtx_code code = GET_CODE (increment);
1591 src_insn = PREV_INSN (src_insn);
1592 increment = SET_SRC (PATTERN (src_insn));
1593 /* Don't need the last insn anymore. */
1594 delete_insn (get_last_insn ());
1596 if (GET_CODE (second_part) != CONST_INT
1597 || GET_CODE (increment) != CONST_INT)
1601 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1602 else if (code == PLUS)
1603 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1605 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1608 if (GET_CODE (increment) != CONST_INT)
1611 /* The insn loading the constant into a register is no longer needed,
1613 delete_insn (get_last_insn ());
1616 if (increment_total)
1617 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1619 increment_total = increment;
1621 /* Check that the source register is the same as the register we expected
1622 to see as the source. If not, something is seriously wrong. */
1623 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1624 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1626 /* Some machines (e.g. the romp), may emit two add instructions for
1627 certain constants, so lets try looking for another add immediately
1628 before this one if we have only seen one add insn so far. */
1634 src_insn = PREV_INSN (src_insn);
1635 pattern = PATTERN (src_insn);
1637 delete_insn (get_last_insn ());
1645 return increment_total;
1648 /* Copy REG_NOTES, except for insn references, because not all insn_map
1649 entries are valid yet. We do need to copy registers now though, because
1650 the reg_map entries can change during copying. */
1653 initial_reg_note_copy (notes, map)
1655 struct inline_remap *map;
1662 copy = rtx_alloc (GET_CODE (notes));
1663 PUT_MODE (copy, GET_MODE (notes));
1665 if (GET_CODE (notes) == EXPR_LIST)
1666 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map, 0);
1667 else if (GET_CODE (notes) == INSN_LIST)
1668 /* Don't substitute for these yet. */
1669 XEXP (copy, 0) = XEXP (notes, 0);
1673 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1678 /* Fixup insn references in copied REG_NOTES. */
1681 final_reg_note_copy (notes, map)
1683 struct inline_remap *map;
1687 for (note = notes; note; note = XEXP (note, 1))
1688 if (GET_CODE (note) == INSN_LIST)
1689 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1692 /* Copy each instruction in the loop, substituting from map as appropriate.
1693 This is very similar to a loop in expand_inline_function. */
1696 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1697 unroll_type, start_label, loop_end, insert_before,
1699 rtx copy_start, copy_end;
1700 struct inline_remap *map;
1703 enum unroll_types unroll_type;
1704 rtx start_label, loop_end, insert_before, copy_notes_from;
1707 rtx set, tem, copy = NULL_RTX;
1708 int dest_reg_was_split, i;
1712 rtx final_label = 0;
1713 rtx giv_inc, giv_dest_reg, giv_src_reg;
1715 /* If this isn't the last iteration, then map any references to the
1716 start_label to final_label. Final label will then be emitted immediately
1717 after the end of this loop body if it was ever used.
1719 If this is the last iteration, then map references to the start_label
1721 if (! last_iteration)
1723 final_label = gen_label_rtx ();
1724 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1728 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1732 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1733 Else gen_sequence could return a raw pattern for a jump which we pass
1734 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1735 a variety of losing behaviors later. */
1736 emit_note (0, NOTE_INSN_DELETED);
1741 insn = NEXT_INSN (insn);
1743 map->orig_asm_operands_vector = 0;
1745 switch (GET_CODE (insn))
1748 pattern = PATTERN (insn);
1752 /* Check to see if this is a giv that has been combined with
1753 some split address givs. (Combined in the sense that
1754 `combine_givs' in loop.c has put two givs in the same register.)
1755 In this case, we must search all givs based on the same biv to
1756 find the address givs. Then split the address givs.
1757 Do this before splitting the giv, since that may map the
1758 SET_DEST to a new register. */
1760 if ((set = single_set (insn))
1761 && GET_CODE (SET_DEST (set)) == REG
1762 && addr_combined_regs[REGNO (SET_DEST (set))])
1764 struct iv_class *bl;
1765 struct induction *v, *tv;
1766 int regno = REGNO (SET_DEST (set));
1768 v = addr_combined_regs[REGNO (SET_DEST (set))];
1769 bl = reg_biv_class[REGNO (v->src_reg)];
1771 /* Although the giv_inc amount is not needed here, we must call
1772 calculate_giv_inc here since it might try to delete the
1773 last insn emitted. If we wait until later to call it,
1774 we might accidentally delete insns generated immediately
1775 below by emit_unrolled_add. */
1777 if (! derived_regs[regno])
1778 giv_inc = calculate_giv_inc (set, insn, regno);
1780 /* Now find all address giv's that were combined with this
1782 for (tv = bl->giv; tv; tv = tv->next_iv)
1783 if (tv->giv_type == DEST_ADDR && tv->same == v)
1787 /* If this DEST_ADDR giv was not split, then ignore it. */
1788 if (*tv->location != tv->dest_reg)
1791 /* Scale this_giv_inc if the multiplicative factors of
1792 the two givs are different. */
1793 this_giv_inc = INTVAL (giv_inc);
1794 if (tv->mult_val != v->mult_val)
1795 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1796 * INTVAL (tv->mult_val));
1798 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1799 *tv->location = tv->dest_reg;
1801 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1803 /* Must emit an insn to increment the split address
1804 giv. Add in the const_adjust field in case there
1805 was a constant eliminated from the address. */
1806 rtx value, dest_reg;
1808 /* tv->dest_reg will be either a bare register,
1809 or else a register plus a constant. */
1810 if (GET_CODE (tv->dest_reg) == REG)
1811 dest_reg = tv->dest_reg;
1813 dest_reg = XEXP (tv->dest_reg, 0);
1815 /* Check for shared address givs, and avoid
1816 incrementing the shared pseudo reg more than
1818 if (! tv->same_insn && ! tv->shared)
1820 /* tv->dest_reg may actually be a (PLUS (REG)
1821 (CONST)) here, so we must call plus_constant
1822 to add the const_adjust amount before calling
1823 emit_unrolled_add below. */
1824 value = plus_constant (tv->dest_reg,
1827 if (GET_CODE (value) == PLUS)
1829 /* The constant could be too large for an add
1830 immediate, so can't directly emit an insn
1832 emit_unrolled_add (dest_reg, XEXP (value, 0),
1837 /* Reset the giv to be just the register again, in case
1838 it is used after the set we have just emitted.
1839 We must subtract the const_adjust factor added in
1841 tv->dest_reg = plus_constant (dest_reg,
1842 - tv->const_adjust);
1843 *tv->location = tv->dest_reg;
1848 /* If this is a setting of a splittable variable, then determine
1849 how to split the variable, create a new set based on this split,
1850 and set up the reg_map so that later uses of the variable will
1851 use the new split variable. */
1853 dest_reg_was_split = 0;
1855 if ((set = single_set (insn))
1856 && GET_CODE (SET_DEST (set)) == REG
1857 && splittable_regs[REGNO (SET_DEST (set))])
1859 int regno = REGNO (SET_DEST (set));
1862 dest_reg_was_split = 1;
1864 giv_dest_reg = SET_DEST (set);
1865 if (derived_regs[regno])
1867 /* ??? This relies on SET_SRC (SET) to be of
1868 the form (plus (reg) (const_int)), and thus
1869 forces recombine_givs to restrict the kind
1870 of giv derivations it does before unrolling. */
1871 giv_src_reg = XEXP (SET_SRC (set), 0);
1872 giv_inc = XEXP (SET_SRC (set), 1);
1876 giv_src_reg = giv_dest_reg;
1877 /* Compute the increment value for the giv, if it wasn't
1878 already computed above. */
1880 giv_inc = calculate_giv_inc (set, insn, regno);
1882 src_regno = REGNO (giv_src_reg);
1884 if (unroll_type == UNROLL_COMPLETELY)
1886 /* Completely unrolling the loop. Set the induction
1887 variable to a known constant value. */
1889 /* The value in splittable_regs may be an invariant
1890 value, so we must use plus_constant here. */
1891 splittable_regs[regno]
1892 = plus_constant (splittable_regs[src_regno],
1895 if (GET_CODE (splittable_regs[regno]) == PLUS)
1897 giv_src_reg = XEXP (splittable_regs[regno], 0);
1898 giv_inc = XEXP (splittable_regs[regno], 1);
1902 /* The splittable_regs value must be a REG or a
1903 CONST_INT, so put the entire value in the giv_src_reg
1905 giv_src_reg = splittable_regs[regno];
1906 giv_inc = const0_rtx;
1911 /* Partially unrolling loop. Create a new pseudo
1912 register for the iteration variable, and set it to
1913 be a constant plus the original register. Except
1914 on the last iteration, when the result has to
1915 go back into the original iteration var register. */
1917 /* Handle bivs which must be mapped to a new register
1918 when split. This happens for bivs which need their
1919 final value set before loop entry. The new register
1920 for the biv was stored in the biv's first struct
1921 induction entry by find_splittable_regs. */
1923 if (regno < max_reg_before_loop
1924 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1926 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1927 giv_dest_reg = giv_src_reg;
1931 /* If non-reduced/final-value givs were split, then
1932 this would have to remap those givs also. See
1933 find_splittable_regs. */
1936 splittable_regs[regno]
1937 = GEN_INT (INTVAL (giv_inc)
1938 + INTVAL (splittable_regs[src_regno]));
1939 giv_inc = splittable_regs[regno];
1941 /* Now split the induction variable by changing the dest
1942 of this insn to a new register, and setting its
1943 reg_map entry to point to this new register.
1945 If this is the last iteration, and this is the last insn
1946 that will update the iv, then reuse the original dest,
1947 to ensure that the iv will have the proper value when
1948 the loop exits or repeats.
1950 Using splittable_regs_updates here like this is safe,
1951 because it can only be greater than one if all
1952 instructions modifying the iv are always executed in
1955 if (! last_iteration
1956 || (splittable_regs_updates[regno]-- != 1))
1958 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1960 map->reg_map[regno] = tem;
1961 record_base_value (REGNO (tem),
1962 giv_inc == const0_rtx
1964 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1965 giv_src_reg, giv_inc),
1969 map->reg_map[regno] = giv_src_reg;
1972 /* The constant being added could be too large for an add
1973 immediate, so can't directly emit an insn here. */
1974 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1975 copy = get_last_insn ();
1976 pattern = PATTERN (copy);
1980 pattern = copy_rtx_and_substitute (pattern, map, 0);
1981 copy = emit_insn (pattern);
1983 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1986 /* If this insn is setting CC0, it may need to look at
1987 the insn that uses CC0 to see what type of insn it is.
1988 In that case, the call to recog via validate_change will
1989 fail. So don't substitute constants here. Instead,
1990 do it when we emit the following insn.
1992 For example, see the pyr.md file. That machine has signed and
1993 unsigned compares. The compare patterns must check the
1994 following branch insn to see which what kind of compare to
1997 If the previous insn set CC0, substitute constants on it as
1999 if (sets_cc0_p (PATTERN (copy)) != 0)
2004 try_constants (cc0_insn, map);
2006 try_constants (copy, map);
2009 try_constants (copy, map);
2012 /* Make split induction variable constants `permanent' since we
2013 know there are no backward branches across iteration variable
2014 settings which would invalidate this. */
2015 if (dest_reg_was_split)
2017 int regno = REGNO (SET_DEST (set));
2019 if ((size_t) regno < VARRAY_SIZE (map->const_equiv_varray)
2020 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
2022 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
2027 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2028 copy = emit_jump_insn (pattern);
2029 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2031 if (JUMP_LABEL (insn) == start_label && insn == copy_end
2032 && ! last_iteration)
2034 /* This is a branch to the beginning of the loop; this is the
2035 last insn being copied; and this is not the last iteration.
2036 In this case, we want to change the original fall through
2037 case to be a branch past the end of the loop, and the
2038 original jump label case to fall_through. */
2040 if (invert_exp (pattern, copy))
2042 if (! redirect_exp (&pattern,
2043 get_label_from_map (map,
2045 (JUMP_LABEL (insn))),
2052 rtx lab = gen_label_rtx ();
2053 /* Can't do it by reversing the jump (probably because we
2054 couldn't reverse the conditions), so emit a new
2055 jump_insn after COPY, and redirect the jump around
2057 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2058 jmp = emit_barrier_after (jmp);
2059 emit_label_after (lab, jmp);
2060 LABEL_NUSES (lab) = 0;
2061 if (! redirect_exp (&pattern,
2062 get_label_from_map (map,
2064 (JUMP_LABEL (insn))),
2072 try_constants (cc0_insn, map);
2075 try_constants (copy, map);
2077 /* Set the jump label of COPY correctly to avoid problems with
2078 later passes of unroll_loop, if INSN had jump label set. */
2079 if (JUMP_LABEL (insn))
2083 /* Can't use the label_map for every insn, since this may be
2084 the backward branch, and hence the label was not mapped. */
2085 if ((set = single_set (copy)))
2087 tem = SET_SRC (set);
2088 if (GET_CODE (tem) == LABEL_REF)
2089 label = XEXP (tem, 0);
2090 else if (GET_CODE (tem) == IF_THEN_ELSE)
2092 if (XEXP (tem, 1) != pc_rtx)
2093 label = XEXP (XEXP (tem, 1), 0);
2095 label = XEXP (XEXP (tem, 2), 0);
2099 if (label && GET_CODE (label) == CODE_LABEL)
2100 JUMP_LABEL (copy) = label;
2103 /* An unrecognizable jump insn, probably the entry jump
2104 for a switch statement. This label must have been mapped,
2105 so just use the label_map to get the new jump label. */
2107 = get_label_from_map (map,
2108 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2111 /* If this is a non-local jump, then must increase the label
2112 use count so that the label will not be deleted when the
2113 original jump is deleted. */
2114 LABEL_NUSES (JUMP_LABEL (copy))++;
2116 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2117 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2119 rtx pat = PATTERN (copy);
2120 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2121 int len = XVECLEN (pat, diff_vec_p);
2124 for (i = 0; i < len; i++)
2125 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2128 /* If this used to be a conditional jump insn but whose branch
2129 direction is now known, we must do something special. */
2130 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2133 /* If the previous insn set cc0 for us, delete it. */
2134 if (sets_cc0_p (PREV_INSN (copy)))
2135 delete_insn (PREV_INSN (copy));
2138 /* If this is now a no-op, delete it. */
2139 if (map->last_pc_value == pc_rtx)
2141 /* Don't let delete_insn delete the label referenced here,
2142 because we might possibly need it later for some other
2143 instruction in the loop. */
2144 if (JUMP_LABEL (copy))
2145 LABEL_NUSES (JUMP_LABEL (copy))++;
2147 if (JUMP_LABEL (copy))
2148 LABEL_NUSES (JUMP_LABEL (copy))--;
2152 /* Otherwise, this is unconditional jump so we must put a
2153 BARRIER after it. We could do some dead code elimination
2154 here, but jump.c will do it just as well. */
2160 pattern = copy_rtx_and_substitute (PATTERN (insn), map, 0);
2161 copy = emit_call_insn (pattern);
2162 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2164 /* Because the USAGE information potentially contains objects other
2165 than hard registers, we need to copy it. */
2166 CALL_INSN_FUNCTION_USAGE (copy)
2167 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn),
2172 try_constants (cc0_insn, map);
2175 try_constants (copy, map);
2177 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2178 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2179 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2183 /* If this is the loop start label, then we don't need to emit a
2184 copy of this label since no one will use it. */
2186 if (insn != start_label)
2188 copy = emit_label (get_label_from_map (map,
2189 CODE_LABEL_NUMBER (insn)));
2195 copy = emit_barrier ();
2199 /* VTOP and CONT notes are valid only before the loop exit test.
2200 If placed anywhere else, loop may generate bad code. */
2201 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2202 the associated rtl. We do not want to share the structure in
2205 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2206 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2207 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2208 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2209 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2210 copy = emit_note (NOTE_SOURCE_FILE (insn),
2211 NOTE_LINE_NUMBER (insn));
2220 map->insn_map[INSN_UID (insn)] = copy;
2222 while (insn != copy_end);
2224 /* Now finish coping the REG_NOTES. */
2228 insn = NEXT_INSN (insn);
2229 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2230 || GET_CODE (insn) == CALL_INSN)
2231 && map->insn_map[INSN_UID (insn)])
2232 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2234 while (insn != copy_end);
2236 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2237 each of these notes here, since there may be some important ones, such as
2238 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2239 iteration, because the original notes won't be deleted.
2241 We can't use insert_before here, because when from preconditioning,
2242 insert_before points before the loop. We can't use copy_end, because
2243 there may be insns already inserted after it (which we don't want to
2244 copy) when not from preconditioning code. */
2246 if (! last_iteration)
2248 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2250 /* VTOP notes are valid only before the loop exit test.
2251 If placed anywhere else, loop may generate bad code.
2252 There is no need to test for NOTE_INSN_LOOP_CONT notes
2253 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2254 instructions before the last insn in the loop, and if the
2255 end test is that short, there will be a VTOP note between
2256 the CONT note and the test. */
2257 if (GET_CODE (insn) == NOTE
2258 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2259 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2260 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2261 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2265 if (final_label && LABEL_NUSES (final_label) > 0)
2266 emit_label (final_label);
2268 tem = gen_sequence ();
2270 emit_insn_before (tem, insert_before);
2273 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2274 emitted. This will correctly handle the case where the increment value
2275 won't fit in the immediate field of a PLUS insns. */
2278 emit_unrolled_add (dest_reg, src_reg, increment)
2279 rtx dest_reg, src_reg, increment;
2283 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2284 dest_reg, 0, OPTAB_LIB_WIDEN);
2286 if (dest_reg != result)
2287 emit_move_insn (dest_reg, result);
2290 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2291 is a backward branch in that range that branches to somewhere between
2292 LOOP->START and INSN. Returns 0 otherwise. */
2294 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2295 In practice, this is not a problem, because this function is seldom called,
2296 and uses a negligible amount of CPU time on average. */
2299 back_branch_in_range_p (loop, insn)
2300 const struct loop *loop;
2303 rtx p, q, target_insn;
2304 rtx loop_start = loop->start;
2305 rtx loop_end = loop->end;
2306 rtx orig_loop_end = loop->end;
2308 /* Stop before we get to the backward branch at the end of the loop. */
2309 loop_end = prev_nonnote_insn (loop_end);
2310 if (GET_CODE (loop_end) == BARRIER)
2311 loop_end = PREV_INSN (loop_end);
2313 /* Check in case insn has been deleted, search forward for first non
2314 deleted insn following it. */
2315 while (INSN_DELETED_P (insn))
2316 insn = NEXT_INSN (insn);
2318 /* Check for the case where insn is the last insn in the loop. Deal
2319 with the case where INSN was a deleted loop test insn, in which case
2320 it will now be the NOTE_LOOP_END. */
2321 if (insn == loop_end || insn == orig_loop_end)
2324 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2326 if (GET_CODE (p) == JUMP_INSN)
2328 target_insn = JUMP_LABEL (p);
2330 /* Search from loop_start to insn, to see if one of them is
2331 the target_insn. We can't use INSN_LUID comparisons here,
2332 since insn may not have an LUID entry. */
2333 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2334 if (q == target_insn)
2342 /* Try to generate the simplest rtx for the expression
2343 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2347 fold_rtx_mult_add (mult1, mult2, add1, mode)
2348 rtx mult1, mult2, add1;
2349 enum machine_mode mode;
2354 /* The modes must all be the same. This should always be true. For now,
2355 check to make sure. */
2356 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2357 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2358 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2361 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2362 will be a constant. */
2363 if (GET_CODE (mult1) == CONST_INT)
2370 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2372 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2374 /* Again, put the constant second. */
2375 if (GET_CODE (add1) == CONST_INT)
2382 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2384 result = gen_rtx_PLUS (mode, add1, mult_res);
2389 /* Searches the list of induction struct's for the biv BL, to try to calculate
2390 the total increment value for one iteration of the loop as a constant.
2392 Returns the increment value as an rtx, simplified as much as possible,
2393 if it can be calculated. Otherwise, returns 0. */
2396 biv_total_increment (bl)
2397 struct iv_class *bl;
2399 struct induction *v;
2402 /* For increment, must check every instruction that sets it. Each
2403 instruction must be executed only once each time through the loop.
2404 To verify this, we check that the insn is always executed, and that
2405 there are no backward branches after the insn that branch to before it.
2406 Also, the insn must have a mult_val of one (to make sure it really is
2409 result = const0_rtx;
2410 for (v = bl->biv; v; v = v->next_iv)
2412 if (v->always_computable && v->mult_val == const1_rtx
2413 && ! v->maybe_multiple)
2414 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2422 /* Determine the initial value of the iteration variable, and the amount
2423 that it is incremented each loop. Use the tables constructed by
2424 the strength reduction pass to calculate these values.
2426 Initial_value and/or increment are set to zero if their values could not
2430 iteration_info (loop, iteration_var, initial_value, increment)
2431 const struct loop *loop ATTRIBUTE_UNUSED;
2432 rtx iteration_var, *initial_value, *increment;
2434 struct iv_class *bl;
2436 /* Clear the result values, in case no answer can be found. */
2440 /* The iteration variable can be either a giv or a biv. Check to see
2441 which it is, and compute the variable's initial value, and increment
2442 value if possible. */
2444 /* If this is a new register, can't handle it since we don't have any
2445 reg_iv_type entry for it. */
2446 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
2448 if (loop_dump_stream)
2449 fprintf (loop_dump_stream,
2450 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2454 /* Reject iteration variables larger than the host wide int size, since they
2455 could result in a number of iterations greater than the range of our
2456 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2457 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2458 > HOST_BITS_PER_WIDE_INT))
2460 if (loop_dump_stream)
2461 fprintf (loop_dump_stream,
2462 "Loop unrolling: Iteration var rejected because mode too large.\n");
2465 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2467 if (loop_dump_stream)
2468 fprintf (loop_dump_stream,
2469 "Loop unrolling: Iteration var not an integer.\n");
2472 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2474 /* When reg_iv_type / reg_iv_info is resized for biv increments
2475 that are turned into givs, reg_biv_class is not resized.
2476 So check here that we don't make an out-of-bounds access. */
2477 if (REGNO (iteration_var) >= max_reg_before_loop)
2480 /* Grab initial value, only useful if it is a constant. */
2481 bl = reg_biv_class[REGNO (iteration_var)];
2482 *initial_value = bl->initial_value;
2484 *increment = biv_total_increment (bl);
2486 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2488 HOST_WIDE_INT offset = 0;
2489 struct induction *v = REG_IV_INFO (REGNO (iteration_var));
2491 if (REGNO (v->src_reg) >= max_reg_before_loop)
2494 bl = reg_biv_class[REGNO (v->src_reg)];
2496 /* Increment value is mult_val times the increment value of the biv. */
2498 *increment = biv_total_increment (bl);
2501 struct induction *biv_inc;
2504 = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, v->mode);
2505 /* The caller assumes that one full increment has occured at the
2506 first loop test. But that's not true when the biv is incremented
2507 after the giv is set (which is the usual case), e.g.:
2508 i = 6; do {;} while (i++ < 9) .
2509 Therefore, we bias the initial value by subtracting the amount of
2510 the increment that occurs between the giv set and the giv test. */
2511 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
2513 if (loop_insn_first_p (v->insn, biv_inc->insn))
2514 offset -= INTVAL (biv_inc->add_val);
2516 offset *= INTVAL (v->mult_val);
2518 if (loop_dump_stream)
2519 fprintf (loop_dump_stream,
2520 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2522 /* Initial value is mult_val times the biv's initial value plus
2523 add_val. Only useful if it is a constant. */
2525 = fold_rtx_mult_add (v->mult_val,
2526 plus_constant (bl->initial_value, offset),
2527 v->add_val, v->mode);
2531 if (loop_dump_stream)
2532 fprintf (loop_dump_stream,
2533 "Loop unrolling: Not basic or general induction var.\n");
2539 /* For each biv and giv, determine whether it can be safely split into
2540 a different variable for each unrolled copy of the loop body. If it
2541 is safe to split, then indicate that by saving some useful info
2542 in the splittable_regs array.
2544 If the loop is being completely unrolled, then splittable_regs will hold
2545 the current value of the induction variable while the loop is unrolled.
2546 It must be set to the initial value of the induction variable here.
2547 Otherwise, splittable_regs will hold the difference between the current
2548 value of the induction variable and the value the induction variable had
2549 at the top of the loop. It must be set to the value 0 here.
2551 Returns the total number of instructions that set registers that are
2554 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2555 constant values are unnecessary, since we can easily calculate increment
2556 values in this case even if nothing is constant. The increment value
2557 should not involve a multiply however. */
2559 /* ?? Even if the biv/giv increment values aren't constant, it may still
2560 be beneficial to split the variable if the loop is only unrolled a few
2561 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2564 find_splittable_regs (loop, unroll_type, end_insert_before, unroll_number)
2565 const struct loop *loop;
2566 enum unroll_types unroll_type;
2567 rtx end_insert_before;
2570 struct iv_class *bl;
2571 struct induction *v;
2573 rtx biv_final_value;
2576 rtx loop_start = loop->start;
2577 rtx loop_end = loop->end;
2579 for (bl = loop_iv_list; bl; bl = bl->next)
2581 /* Biv_total_increment must return a constant value,
2582 otherwise we can not calculate the split values. */
2584 increment = biv_total_increment (bl);
2585 if (! increment || GET_CODE (increment) != CONST_INT)
2588 /* The loop must be unrolled completely, or else have a known number
2589 of iterations and only one exit, or else the biv must be dead
2590 outside the loop, or else the final value must be known. Otherwise,
2591 it is unsafe to split the biv since it may not have the proper
2592 value on loop exit. */
2594 /* loop_number_exit_count is non-zero if the loop has an exit other than
2595 a fall through at the end. */
2598 biv_final_value = 0;
2599 if (unroll_type != UNROLL_COMPLETELY
2600 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2601 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2603 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2604 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2605 < INSN_LUID (bl->init_insn))
2606 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2607 && ! (biv_final_value = final_biv_value (loop, bl)))
2610 /* If any of the insns setting the BIV don't do so with a simple
2611 PLUS, we don't know how to split it. */
2612 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2613 if ((tem = single_set (v->insn)) == 0
2614 || GET_CODE (SET_DEST (tem)) != REG
2615 || REGNO (SET_DEST (tem)) != bl->regno
2616 || GET_CODE (SET_SRC (tem)) != PLUS)
2619 /* If final value is non-zero, then must emit an instruction which sets
2620 the value of the biv to the proper value. This is done after
2621 handling all of the givs, since some of them may need to use the
2622 biv's value in their initialization code. */
2624 /* This biv is splittable. If completely unrolling the loop, save
2625 the biv's initial value. Otherwise, save the constant zero. */
2627 if (biv_splittable == 1)
2629 if (unroll_type == UNROLL_COMPLETELY)
2631 /* If the initial value of the biv is itself (i.e. it is too
2632 complicated for strength_reduce to compute), or is a hard
2633 register, or it isn't invariant, then we must create a new
2634 pseudo reg to hold the initial value of the biv. */
2636 if (GET_CODE (bl->initial_value) == REG
2637 && (REGNO (bl->initial_value) == bl->regno
2638 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2639 || ! loop_invariant_p (loop, bl->initial_value)))
2641 rtx tem = gen_reg_rtx (bl->biv->mode);
2643 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2644 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2647 if (loop_dump_stream)
2648 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2649 bl->regno, REGNO (tem));
2651 splittable_regs[bl->regno] = tem;
2654 splittable_regs[bl->regno] = bl->initial_value;
2657 splittable_regs[bl->regno] = const0_rtx;
2659 /* Save the number of instructions that modify the biv, so that
2660 we can treat the last one specially. */
2662 splittable_regs_updates[bl->regno] = bl->biv_count;
2663 result += bl->biv_count;
2665 if (loop_dump_stream)
2666 fprintf (loop_dump_stream,
2667 "Biv %d safe to split.\n", bl->regno);
2670 /* Check every giv that depends on this biv to see whether it is
2671 splittable also. Even if the biv isn't splittable, givs which
2672 depend on it may be splittable if the biv is live outside the
2673 loop, and the givs aren't. */
2675 result += find_splittable_givs (loop, bl, unroll_type, increment,
2678 /* If final value is non-zero, then must emit an instruction which sets
2679 the value of the biv to the proper value. This is done after
2680 handling all of the givs, since some of them may need to use the
2681 biv's value in their initialization code. */
2682 if (biv_final_value)
2684 /* If the loop has multiple exits, emit the insns before the
2685 loop to ensure that it will always be executed no matter
2686 how the loop exits. Otherwise emit the insn after the loop,
2687 since this is slightly more efficient. */
2688 if (! loop->exit_count)
2689 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2694 /* Create a new register to hold the value of the biv, and then
2695 set the biv to its final value before the loop start. The biv
2696 is set to its final value before loop start to ensure that
2697 this insn will always be executed, no matter how the loop
2699 rtx tem = gen_reg_rtx (bl->biv->mode);
2700 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2702 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2704 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2708 if (loop_dump_stream)
2709 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2710 REGNO (bl->biv->src_reg), REGNO (tem));
2712 /* Set up the mapping from the original biv register to the new
2714 bl->biv->src_reg = tem;
2721 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2722 for the instruction that is using it. Do not make any changes to that
2726 verify_addresses (v, giv_inc, unroll_number)
2727 struct induction *v;
2732 rtx orig_addr = *v->location;
2733 rtx last_addr = plus_constant (v->dest_reg,
2734 INTVAL (giv_inc) * (unroll_number - 1));
2736 /* First check to see if either address would fail. Handle the fact
2737 that we have may have a match_dup. */
2738 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2739 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2742 /* Now put things back the way they were before. This should always
2744 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2750 /* For every giv based on the biv BL, check to determine whether it is
2751 splittable. This is a subroutine to find_splittable_regs ().
2753 Return the number of instructions that set splittable registers. */
2756 find_splittable_givs (loop, bl, unroll_type, increment, unroll_number)
2757 const struct loop *loop;
2758 struct iv_class *bl;
2759 enum unroll_types unroll_type;
2763 struct induction *v, *v2;
2768 /* Scan the list of givs, and set the same_insn field when there are
2769 multiple identical givs in the same insn. */
2770 for (v = bl->giv; v; v = v->next_iv)
2771 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2772 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2776 for (v = bl->giv; v; v = v->next_iv)
2780 /* Only split the giv if it has already been reduced, or if the loop is
2781 being completely unrolled. */
2782 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2785 /* The giv can be split if the insn that sets the giv is executed once
2786 and only once on every iteration of the loop. */
2787 /* An address giv can always be split. v->insn is just a use not a set,
2788 and hence it does not matter whether it is always executed. All that
2789 matters is that all the biv increments are always executed, and we
2790 won't reach here if they aren't. */
2791 if (v->giv_type != DEST_ADDR
2792 && (! v->always_computable
2793 || back_branch_in_range_p (loop, v->insn)))
2796 /* The giv increment value must be a constant. */
2797 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2799 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2802 /* The loop must be unrolled completely, or else have a known number of
2803 iterations and only one exit, or else the giv must be dead outside
2804 the loop, or else the final value of the giv must be known.
2805 Otherwise, it is not safe to split the giv since it may not have the
2806 proper value on loop exit. */
2808 /* The used outside loop test will fail for DEST_ADDR givs. They are
2809 never used outside the loop anyways, so it is always safe to split a
2813 if (unroll_type != UNROLL_COMPLETELY
2814 && (loop->exit_count || unroll_type == UNROLL_NAIVE)
2815 && v->giv_type != DEST_ADDR
2816 /* The next part is true if the pseudo is used outside the loop.
2817 We assume that this is true for any pseudo created after loop
2818 starts, because we don't have a reg_n_info entry for them. */
2819 && (REGNO (v->dest_reg) >= max_reg_before_loop
2820 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2821 /* Check for the case where the pseudo is set by a shift/add
2822 sequence, in which case the first insn setting the pseudo
2823 is the first insn of the shift/add sequence. */
2824 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2825 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2826 != INSN_UID (XEXP (tem, 0)))))
2827 /* Line above always fails if INSN was moved by loop opt. */
2828 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2829 >= INSN_LUID (loop->end)))
2830 /* Givs made from biv increments are missed by the above test, so
2831 test explicitly for them. */
2832 && (REGNO (v->dest_reg) < first_increment_giv
2833 || REGNO (v->dest_reg) > last_increment_giv)
2834 && ! (final_value = v->final_value))
2838 /* Currently, non-reduced/final-value givs are never split. */
2839 /* Should emit insns after the loop if possible, as the biv final value
2842 /* If the final value is non-zero, and the giv has not been reduced,
2843 then must emit an instruction to set the final value. */
2844 if (final_value && !v->new_reg)
2846 /* Create a new register to hold the value of the giv, and then set
2847 the giv to its final value before the loop start. The giv is set
2848 to its final value before loop start to ensure that this insn
2849 will always be executed, no matter how we exit. */
2850 tem = gen_reg_rtx (v->mode);
2851 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2852 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2855 if (loop_dump_stream)
2856 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2857 REGNO (v->dest_reg), REGNO (tem));
2863 /* This giv is splittable. If completely unrolling the loop, save the
2864 giv's initial value. Otherwise, save the constant zero for it. */
2866 if (unroll_type == UNROLL_COMPLETELY)
2868 /* It is not safe to use bl->initial_value here, because it may not
2869 be invariant. It is safe to use the initial value stored in
2870 the splittable_regs array if it is set. In rare cases, it won't
2871 be set, so then we do exactly the same thing as
2872 find_splittable_regs does to get a safe value. */
2873 rtx biv_initial_value;
2875 if (splittable_regs[bl->regno])
2876 biv_initial_value = splittable_regs[bl->regno];
2877 else if (GET_CODE (bl->initial_value) != REG
2878 || (REGNO (bl->initial_value) != bl->regno
2879 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2880 biv_initial_value = bl->initial_value;
2883 rtx tem = gen_reg_rtx (bl->biv->mode);
2885 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2886 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2888 biv_initial_value = tem;
2890 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2891 v->add_val, v->mode);
2898 /* If a giv was combined with another giv, then we can only split
2899 this giv if the giv it was combined with was reduced. This
2900 is because the value of v->new_reg is meaningless in this
2902 if (v->same && ! v->same->new_reg)
2904 if (loop_dump_stream)
2905 fprintf (loop_dump_stream,
2906 "giv combined with unreduced giv not split.\n");
2909 /* If the giv is an address destination, it could be something other
2910 than a simple register, these have to be treated differently. */
2911 else if (v->giv_type == DEST_REG)
2913 /* If value is not a constant, register, or register plus
2914 constant, then compute its value into a register before
2915 loop start. This prevents invalid rtx sharing, and should
2916 generate better code. We can use bl->initial_value here
2917 instead of splittable_regs[bl->regno] because this code
2918 is going before the loop start. */
2919 if (unroll_type == UNROLL_COMPLETELY
2920 && GET_CODE (value) != CONST_INT
2921 && GET_CODE (value) != REG
2922 && (GET_CODE (value) != PLUS
2923 || GET_CODE (XEXP (value, 0)) != REG
2924 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2926 rtx tem = gen_reg_rtx (v->mode);
2927 record_base_value (REGNO (tem), v->add_val, 0);
2928 emit_iv_add_mult (bl->initial_value, v->mult_val,
2929 v->add_val, tem, loop->start);
2933 splittable_regs[REGNO (v->new_reg)] = value;
2934 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2938 /* Splitting address givs is useful since it will often allow us
2939 to eliminate some increment insns for the base giv as
2942 /* If the addr giv is combined with a dest_reg giv, then all
2943 references to that dest reg will be remapped, which is NOT
2944 what we want for split addr regs. We always create a new
2945 register for the split addr giv, just to be safe. */
2947 /* If we have multiple identical address givs within a
2948 single instruction, then use a single pseudo reg for
2949 both. This is necessary in case one is a match_dup
2952 v->const_adjust = 0;
2956 v->dest_reg = v->same_insn->dest_reg;
2957 if (loop_dump_stream)
2958 fprintf (loop_dump_stream,
2959 "Sharing address givs in insn %d\n",
2960 INSN_UID (v->insn));
2962 /* If multiple address GIVs have been combined with the
2963 same dest_reg GIV, do not create a new register for
2965 else if (unroll_type != UNROLL_COMPLETELY
2966 && v->giv_type == DEST_ADDR
2967 && v->same && v->same->giv_type == DEST_ADDR
2968 && v->same->unrolled
2969 /* combine_givs_p may return true for some cases
2970 where the add and mult values are not equal.
2971 To share a register here, the values must be
2973 && rtx_equal_p (v->same->mult_val, v->mult_val)
2974 && rtx_equal_p (v->same->add_val, v->add_val)
2975 /* If the memory references have different modes,
2976 then the address may not be valid and we must
2977 not share registers. */
2978 && verify_addresses (v, giv_inc, unroll_number))
2980 v->dest_reg = v->same->dest_reg;
2983 else if (unroll_type != UNROLL_COMPLETELY)
2985 /* If not completely unrolling the loop, then create a new
2986 register to hold the split value of the DEST_ADDR giv.
2987 Emit insn to initialize its value before loop start. */
2989 rtx tem = gen_reg_rtx (v->mode);
2990 struct induction *same = v->same;
2991 rtx new_reg = v->new_reg;
2992 record_base_value (REGNO (tem), v->add_val, 0);
2994 if (same && same->derived_from)
2996 /* calculate_giv_inc doesn't work for derived givs.
2997 copy_loop_body works around the problem for the
2998 DEST_REG givs themselves, but it can't handle
2999 DEST_ADDR givs that have been combined with
3000 a derived DEST_REG giv.
3001 So Handle V as if the giv from which V->SAME has
3002 been derived has been combined with V.
3003 recombine_givs only derives givs from givs that
3004 are reduced the ordinary, so we need not worry
3005 about same->derived_from being in turn derived. */
3007 same = same->derived_from;
3008 new_reg = express_from (same, v);
3009 new_reg = replace_rtx (new_reg, same->dest_reg,
3013 /* If the address giv has a constant in its new_reg value,
3014 then this constant can be pulled out and put in value,
3015 instead of being part of the initialization code. */
3017 if (GET_CODE (new_reg) == PLUS
3018 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
3021 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
3023 /* Only succeed if this will give valid addresses.
3024 Try to validate both the first and the last
3025 address resulting from loop unrolling, if
3026 one fails, then can't do const elim here. */
3027 if (verify_addresses (v, giv_inc, unroll_number))
3029 /* Save the negative of the eliminated const, so
3030 that we can calculate the dest_reg's increment
3032 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
3034 new_reg = XEXP (new_reg, 0);
3035 if (loop_dump_stream)
3036 fprintf (loop_dump_stream,
3037 "Eliminating constant from giv %d\n",
3046 /* If the address hasn't been checked for validity yet, do so
3047 now, and fail completely if either the first or the last
3048 unrolled copy of the address is not a valid address
3049 for the instruction that uses it. */
3050 if (v->dest_reg == tem
3051 && ! verify_addresses (v, giv_inc, unroll_number))
3053 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3054 if (v2->same_insn == v)
3057 if (loop_dump_stream)
3058 fprintf (loop_dump_stream,
3059 "Invalid address for giv at insn %d\n",
3060 INSN_UID (v->insn));
3064 v->new_reg = new_reg;
3067 /* We set this after the address check, to guarantee that
3068 the register will be initialized. */
3071 /* To initialize the new register, just move the value of
3072 new_reg into it. This is not guaranteed to give a valid
3073 instruction on machines with complex addressing modes.
3074 If we can't recognize it, then delete it and emit insns
3075 to calculate the value from scratch. */
3076 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
3077 copy_rtx (v->new_reg)),
3079 if (recog_memoized (PREV_INSN (loop->start)) < 0)
3083 /* We can't use bl->initial_value to compute the initial
3084 value, because the loop may have been preconditioned.
3085 We must calculate it from NEW_REG. Try using
3086 force_operand instead of emit_iv_add_mult. */
3087 delete_insn (PREV_INSN (loop->start));
3090 ret = force_operand (v->new_reg, tem);
3092 emit_move_insn (tem, ret);
3093 sequence = gen_sequence ();
3095 emit_insn_before (sequence, loop->start);
3097 if (loop_dump_stream)
3098 fprintf (loop_dump_stream,
3099 "Invalid init insn, rewritten.\n");
3104 v->dest_reg = value;
3106 /* Check the resulting address for validity, and fail
3107 if the resulting address would be invalid. */
3108 if (! verify_addresses (v, giv_inc, unroll_number))
3110 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3111 if (v2->same_insn == v)
3114 if (loop_dump_stream)
3115 fprintf (loop_dump_stream,
3116 "Invalid address for giv at insn %d\n",
3117 INSN_UID (v->insn));
3120 if (v->same && v->same->derived_from)
3122 /* Handle V as if the giv from which V->SAME has
3123 been derived has been combined with V. */
3125 v->same = v->same->derived_from;
3126 v->new_reg = express_from (v->same, v);
3127 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3133 /* Store the value of dest_reg into the insn. This sharing
3134 will not be a problem as this insn will always be copied
3137 *v->location = v->dest_reg;
3139 /* If this address giv is combined with a dest reg giv, then
3140 save the base giv's induction pointer so that we will be
3141 able to handle this address giv properly. The base giv
3142 itself does not have to be splittable. */
3144 if (v->same && v->same->giv_type == DEST_REG)
3145 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3147 if (GET_CODE (v->new_reg) == REG)
3149 /* This giv maybe hasn't been combined with any others.
3150 Make sure that it's giv is marked as splittable here. */
3152 splittable_regs[REGNO (v->new_reg)] = value;
3153 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3155 /* Make it appear to depend upon itself, so that the
3156 giv will be properly split in the main loop above. */
3160 addr_combined_regs[REGNO (v->new_reg)] = v;
3164 if (loop_dump_stream)
3165 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3171 /* Currently, unreduced giv's can't be split. This is not too much
3172 of a problem since unreduced giv's are not live across loop
3173 iterations anyways. When unrolling a loop completely though,
3174 it makes sense to reduce&split givs when possible, as this will
3175 result in simpler instructions, and will not require that a reg
3176 be live across loop iterations. */
3178 splittable_regs[REGNO (v->dest_reg)] = value;
3179 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3180 REGNO (v->dest_reg), INSN_UID (v->insn));
3186 /* Unreduced givs are only updated once by definition. Reduced givs
3187 are updated as many times as their biv is. Mark it so if this is
3188 a splittable register. Don't need to do anything for address givs
3189 where this may not be a register. */
3191 if (GET_CODE (v->new_reg) == REG)
3195 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3197 if (count > 1 && v->derived_from)
3198 /* In this case, there is one set where the giv insn was and one
3199 set each after each biv increment. (Most are likely dead.) */
3202 splittable_regs_updates[REGNO (v->new_reg)] = count;
3207 if (loop_dump_stream)
3211 if (GET_CODE (v->dest_reg) == CONST_INT)
3213 else if (GET_CODE (v->dest_reg) != REG)
3214 regnum = REGNO (XEXP (v->dest_reg, 0));
3216 regnum = REGNO (v->dest_reg);
3217 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3218 regnum, INSN_UID (v->insn));
3225 /* Try to prove that the register is dead after the loop exits. Trace every
3226 loop exit looking for an insn that will always be executed, which sets
3227 the register to some value, and appears before the first use of the register
3228 is found. If successful, then return 1, otherwise return 0. */
3230 /* ?? Could be made more intelligent in the handling of jumps, so that
3231 it can search past if statements and other similar structures. */
3234 reg_dead_after_loop (loop, reg)
3235 const struct loop *loop;
3241 int label_count = 0;
3243 /* In addition to checking all exits of this loop, we must also check
3244 all exits of inner nested loops that would exit this loop. We don't
3245 have any way to identify those, so we just give up if there are any
3246 such inner loop exits. */
3248 for (label = loop->exit_labels; label; label = LABEL_NEXTREF (label))
3251 if (label_count != loop->exit_count)
3254 /* HACK: Must also search the loop fall through exit, create a label_ref
3255 here which points to the loop->end, and append the loop_number_exit_labels
3257 label = gen_rtx_LABEL_REF (VOIDmode, loop->end);
3258 LABEL_NEXTREF (label) = loop->exit_labels;
3260 for ( ; label; label = LABEL_NEXTREF (label))
3262 /* Succeed if find an insn which sets the biv or if reach end of
3263 function. Fail if find an insn that uses the biv, or if come to
3264 a conditional jump. */
3266 insn = NEXT_INSN (XEXP (label, 0));
3269 code = GET_CODE (insn);
3270 if (GET_RTX_CLASS (code) == 'i')
3274 if (reg_referenced_p (reg, PATTERN (insn)))
3277 set = single_set (insn);
3278 if (set && rtx_equal_p (SET_DEST (set), reg))
3282 if (code == JUMP_INSN)
3284 if (GET_CODE (PATTERN (insn)) == RETURN)
3286 else if (! simplejump_p (insn)
3287 /* Prevent infinite loop following infinite loops. */
3288 || jump_count++ > 20)
3291 insn = JUMP_LABEL (insn);
3294 insn = NEXT_INSN (insn);
3298 /* Success, the register is dead on all loop exits. */
3302 /* Try to calculate the final value of the biv, the value it will have at
3303 the end of the loop. If we can do it, return that value. */
3306 final_biv_value (loop, bl)
3307 const struct loop *loop;
3308 struct iv_class *bl;
3310 rtx loop_end = loop->end;
3311 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3314 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3316 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3319 /* The final value for reversed bivs must be calculated differently than
3320 for ordinary bivs. In this case, there is already an insn after the
3321 loop which sets this biv's final value (if necessary), and there are
3322 no other loop exits, so we can return any value. */
3325 if (loop_dump_stream)
3326 fprintf (loop_dump_stream,
3327 "Final biv value for %d, reversed biv.\n", bl->regno);
3332 /* Try to calculate the final value as initial value + (number of iterations
3333 * increment). For this to work, increment must be invariant, the only
3334 exit from the loop must be the fall through at the bottom (otherwise
3335 it may not have its final value when the loop exits), and the initial
3336 value of the biv must be invariant. */
3338 if (n_iterations != 0
3339 && ! loop->exit_count
3340 && loop_invariant_p (loop, bl->initial_value))
3342 increment = biv_total_increment (bl);
3344 if (increment && loop_invariant_p (loop, increment))
3346 /* Can calculate the loop exit value, emit insns after loop
3347 end to calculate this value into a temporary register in
3348 case it is needed later. */
3350 tem = gen_reg_rtx (bl->biv->mode);
3351 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3352 /* Make sure loop_end is not the last insn. */
3353 if (NEXT_INSN (loop_end) == 0)
3354 emit_note_after (NOTE_INSN_DELETED, loop_end);
3355 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3356 bl->initial_value, tem, NEXT_INSN (loop_end));
3358 if (loop_dump_stream)
3359 fprintf (loop_dump_stream,
3360 "Final biv value for %d, calculated.\n", bl->regno);
3366 /* Check to see if the biv is dead at all loop exits. */
3367 if (reg_dead_after_loop (loop, bl->biv->src_reg))
3369 if (loop_dump_stream)
3370 fprintf (loop_dump_stream,
3371 "Final biv value for %d, biv dead after loop exit.\n",
3380 /* Try to calculate the final value of the giv, the value it will have at
3381 the end of the loop. If we can do it, return that value. */
3384 final_giv_value (loop, v)
3385 const struct loop *loop;
3386 struct induction *v;
3388 struct iv_class *bl;
3391 rtx insert_before, seq;
3392 rtx loop_end = loop->end;
3393 unsigned HOST_WIDE_INT n_iterations = LOOP_INFO (loop)->n_iterations;
3395 bl = reg_biv_class[REGNO (v->src_reg)];
3397 /* The final value for givs which depend on reversed bivs must be calculated
3398 differently than for ordinary givs. In this case, there is already an
3399 insn after the loop which sets this giv's final value (if necessary),
3400 and there are no other loop exits, so we can return any value. */
3403 if (loop_dump_stream)
3404 fprintf (loop_dump_stream,
3405 "Final giv value for %d, depends on reversed biv\n",
3406 REGNO (v->dest_reg));
3410 /* Try to calculate the final value as a function of the biv it depends
3411 upon. The only exit from the loop must be the fall through at the bottom
3412 (otherwise it may not have its final value when the loop exits). */
3414 /* ??? Can calculate the final giv value by subtracting off the
3415 extra biv increments times the giv's mult_val. The loop must have
3416 only one exit for this to work, but the loop iterations does not need
3419 if (n_iterations != 0
3420 && ! loop->exit_count)
3422 /* ?? It is tempting to use the biv's value here since these insns will
3423 be put after the loop, and hence the biv will have its final value
3424 then. However, this fails if the biv is subsequently eliminated.
3425 Perhaps determine whether biv's are eliminable before trying to
3426 determine whether giv's are replaceable so that we can use the
3427 biv value here if it is not eliminable. */
3429 /* We are emitting code after the end of the loop, so we must make
3430 sure that bl->initial_value is still valid then. It will still
3431 be valid if it is invariant. */
3433 increment = biv_total_increment (bl);
3435 if (increment && loop_invariant_p (loop, increment)
3436 && loop_invariant_p (loop, bl->initial_value))
3438 /* Can calculate the loop exit value of its biv as
3439 (n_iterations * increment) + initial_value */
3441 /* The loop exit value of the giv is then
3442 (final_biv_value - extra increments) * mult_val + add_val.
3443 The extra increments are any increments to the biv which
3444 occur in the loop after the giv's value is calculated.
3445 We must search from the insn that sets the giv to the end
3446 of the loop to calculate this value. */
3448 insert_before = NEXT_INSN (loop_end);
3450 /* Put the final biv value in tem. */
3451 tem = gen_reg_rtx (bl->biv->mode);
3452 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3453 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3454 bl->initial_value, tem, insert_before);
3456 /* Subtract off extra increments as we find them. */
3457 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3458 insn = NEXT_INSN (insn))
3460 struct induction *biv;
3462 for (biv = bl->biv; biv; biv = biv->next_iv)
3463 if (biv->insn == insn)
3466 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3467 biv->add_val, NULL_RTX, 0,
3469 seq = gen_sequence ();
3471 emit_insn_before (seq, insert_before);
3475 /* Now calculate the giv's final value. */
3476 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3479 if (loop_dump_stream)
3480 fprintf (loop_dump_stream,
3481 "Final giv value for %d, calc from biv's value.\n",
3482 REGNO (v->dest_reg));
3488 /* Replaceable giv's should never reach here. */
3492 /* Check to see if the biv is dead at all loop exits. */
3493 if (reg_dead_after_loop (loop, v->dest_reg))
3495 if (loop_dump_stream)
3496 fprintf (loop_dump_stream,
3497 "Final giv value for %d, giv dead after loop exit.\n",
3498 REGNO (v->dest_reg));
3507 /* Look back before LOOP->START for then insn that sets REG and return
3508 the equivalent constant if there is a REG_EQUAL note otherwise just
3509 the SET_SRC of REG. */
3512 loop_find_equiv_value (loop, reg)
3513 const struct loop *loop;
3516 rtx loop_start = loop->start;
3521 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3523 if (GET_CODE (insn) == CODE_LABEL)
3526 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3527 && reg_set_p (reg, insn))
3529 /* We found the last insn before the loop that sets the register.
3530 If it sets the entire register, and has a REG_EQUAL note,
3531 then use the value of the REG_EQUAL note. */
3532 if ((set = single_set (insn))
3533 && (SET_DEST (set) == reg))
3535 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3537 /* Only use the REG_EQUAL note if it is a constant.
3538 Other things, divide in particular, will cause
3539 problems later if we use them. */
3540 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3541 && CONSTANT_P (XEXP (note, 0)))
3542 ret = XEXP (note, 0);
3544 ret = SET_SRC (set);
3552 /* Return a simplified rtx for the expression OP - REG.
3554 REG must appear in OP, and OP must be a register or the sum of a register
3557 Thus, the return value must be const0_rtx or the second term.
3559 The caller is responsible for verifying that REG appears in OP and OP has
3563 subtract_reg_term (op, reg)
3568 if (GET_CODE (op) == PLUS)
3570 if (XEXP (op, 0) == reg)
3571 return XEXP (op, 1);
3572 else if (XEXP (op, 1) == reg)
3573 return XEXP (op, 0);
3575 /* OP does not contain REG as a term. */
3580 /* Find and return register term common to both expressions OP0 and
3581 OP1 or NULL_RTX if no such term exists. Each expression must be a
3582 REG or a PLUS of a REG. */
3585 find_common_reg_term (op0, op1)
3588 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3589 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3596 if (GET_CODE (op0) == PLUS)
3597 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3599 op01 = const0_rtx, op00 = op0;
3601 if (GET_CODE (op1) == PLUS)
3602 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3604 op11 = const0_rtx, op10 = op1;
3606 /* Find and return common register term if present. */
3607 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3609 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3613 /* No common register term found. */
3617 /* Calculate the number of loop iterations. Returns the exact number of loop
3618 iterations if it can be calculated, otherwise returns zero. */
3620 unsigned HOST_WIDE_INT
3621 loop_iterations (loop)
3624 rtx comparison, comparison_value;
3625 rtx iteration_var, initial_value, increment, final_value;
3626 enum rtx_code comparison_code;
3627 HOST_WIDE_INT abs_inc;
3628 unsigned HOST_WIDE_INT abs_diff;
3631 int unsigned_p, compare_dir, final_larger;
3634 struct loop_info *loop_info = LOOP_INFO (loop);
3636 loop_info->n_iterations = 0;
3637 loop_info->initial_value = 0;
3638 loop_info->initial_equiv_value = 0;
3639 loop_info->comparison_value = 0;
3640 loop_info->final_value = 0;
3641 loop_info->final_equiv_value = 0;
3642 loop_info->increment = 0;
3643 loop_info->iteration_var = 0;
3644 loop_info->unroll_number = 1;
3646 /* We used to use prev_nonnote_insn here, but that fails because it might
3647 accidentally get the branch for a contained loop if the branch for this
3648 loop was deleted. We can only trust branches immediately before the
3650 last_loop_insn = PREV_INSN (loop->end);
3652 /* ??? We should probably try harder to find the jump insn
3653 at the end of the loop. The following code assumes that
3654 the last loop insn is a jump to the top of the loop. */
3655 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3657 if (loop_dump_stream)
3658 fprintf (loop_dump_stream,
3659 "Loop iterations: No final conditional branch found.\n");
3663 /* If there is a more than a single jump to the top of the loop
3664 we cannot (easily) determine the iteration count. */
3665 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3667 if (loop_dump_stream)
3668 fprintf (loop_dump_stream,
3669 "Loop iterations: Loop has multiple back edges.\n");
3673 /* Find the iteration variable. If the last insn is a conditional
3674 branch, and the insn before tests a register value, make that the
3675 iteration variable. */
3677 comparison = get_condition_for_loop (loop, last_loop_insn);
3678 if (comparison == 0)
3680 if (loop_dump_stream)
3681 fprintf (loop_dump_stream,
3682 "Loop iterations: No final comparison found.\n");
3686 /* ??? Get_condition may switch position of induction variable and
3687 invariant register when it canonicalizes the comparison. */
3689 comparison_code = GET_CODE (comparison);
3690 iteration_var = XEXP (comparison, 0);
3691 comparison_value = XEXP (comparison, 1);
3693 if (GET_CODE (iteration_var) != REG)
3695 if (loop_dump_stream)
3696 fprintf (loop_dump_stream,
3697 "Loop iterations: Comparison not against register.\n");
3701 /* The only new registers that are created before loop iterations
3702 are givs made from biv increments or registers created by
3703 load_mems. In the latter case, it is possible that try_copy_prop
3704 will propagate a new pseudo into the old iteration register but
3705 this will be marked by having the REG_USERVAR_P bit set. */
3707 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements
3708 && ! REG_USERVAR_P (iteration_var))
3711 iteration_info (loop, iteration_var, &initial_value, &increment);
3713 if (initial_value == 0)
3714 /* iteration_info already printed a message. */
3719 switch (comparison_code)
3734 /* Cannot determine loop iterations with this case. */
3753 /* If the comparison value is an invariant register, then try to find
3754 its value from the insns before the start of the loop. */
3756 final_value = comparison_value;
3757 if (GET_CODE (comparison_value) == REG
3758 && loop_invariant_p (loop, comparison_value))
3760 final_value = loop_find_equiv_value (loop, comparison_value);
3762 /* If we don't get an invariant final value, we are better
3763 off with the original register. */
3764 if (! loop_invariant_p (loop, final_value))
3765 final_value = comparison_value;
3768 /* Calculate the approximate final value of the induction variable
3769 (on the last successful iteration). The exact final value
3770 depends on the branch operator, and increment sign. It will be
3771 wrong if the iteration variable is not incremented by one each
3772 time through the loop and (comparison_value + off_by_one -
3773 initial_value) % increment != 0.
3774 ??? Note that the final_value may overflow and thus final_larger
3775 will be bogus. A potentially infinite loop will be classified
3776 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3778 final_value = plus_constant (final_value, off_by_one);
3780 /* Save the calculated values describing this loop's bounds, in case
3781 precondition_loop_p will need them later. These values can not be
3782 recalculated inside precondition_loop_p because strength reduction
3783 optimizations may obscure the loop's structure.
3785 These values are only required by precondition_loop_p and insert_bct
3786 whenever the number of iterations cannot be computed at compile time.
3787 Only the difference between final_value and initial_value is
3788 important. Note that final_value is only approximate. */
3789 loop_info->initial_value = initial_value;
3790 loop_info->comparison_value = comparison_value;
3791 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3792 loop_info->increment = increment;
3793 loop_info->iteration_var = iteration_var;
3794 loop_info->comparison_code = comparison_code;
3796 /* Try to determine the iteration count for loops such
3797 as (for i = init; i < init + const; i++). When running the
3798 loop optimization twice, the first pass often converts simple
3799 loops into this form. */
3801 if (REG_P (initial_value))
3807 reg1 = initial_value;
3808 if (GET_CODE (final_value) == PLUS)
3809 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3811 reg2 = final_value, const2 = const0_rtx;
3813 /* Check for initial_value = reg1, final_value = reg2 + const2,
3814 where reg1 != reg2. */
3815 if (REG_P (reg2) && reg2 != reg1)
3819 /* Find what reg1 is equivalent to. Hopefully it will
3820 either be reg2 or reg2 plus a constant. */
3821 temp = loop_find_equiv_value (loop, reg1);
3823 if (find_common_reg_term (temp, reg2))
3824 initial_value = temp;
3827 /* Find what reg2 is equivalent to. Hopefully it will
3828 either be reg1 or reg1 plus a constant. Let's ignore
3829 the latter case for now since it is not so common. */
3830 temp = loop_find_equiv_value (loop, reg2);
3832 if (temp == loop_info->iteration_var)
3833 temp = initial_value;
3835 final_value = (const2 == const0_rtx)
3836 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3839 else if (loop->vtop && GET_CODE (reg2) == CONST_INT)
3843 /* When running the loop optimizer twice, check_dbra_loop
3844 further obfuscates reversible loops of the form:
3845 for (i = init; i < init + const; i++). We often end up with
3846 final_value = 0, initial_value = temp, temp = temp2 - init,
3847 where temp2 = init + const. If the loop has a vtop we
3848 can replace initial_value with const. */
3850 temp = loop_find_equiv_value (loop, reg1);
3852 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3854 rtx temp2 = loop_find_equiv_value (loop, XEXP (temp, 0));
3856 if (GET_CODE (temp2) == PLUS
3857 && XEXP (temp2, 0) == XEXP (temp, 1))
3858 initial_value = XEXP (temp2, 1);
3863 /* If have initial_value = reg + const1 and final_value = reg +
3864 const2, then replace initial_value with const1 and final_value
3865 with const2. This should be safe since we are protected by the
3866 initial comparison before entering the loop if we have a vtop.
3867 For example, a + b < a + c is not equivalent to b < c for all a
3868 when using modulo arithmetic.
3870 ??? Without a vtop we could still perform the optimization if we check
3871 the initial and final values carefully. */
3873 && (reg_term = find_common_reg_term (initial_value, final_value)))
3875 initial_value = subtract_reg_term (initial_value, reg_term);
3876 final_value = subtract_reg_term (final_value, reg_term);
3879 loop_info->initial_equiv_value = initial_value;
3880 loop_info->final_equiv_value = final_value;
3882 /* For EQ comparison loops, we don't have a valid final value.
3883 Check this now so that we won't leave an invalid value if we
3884 return early for any other reason. */
3885 if (comparison_code == EQ)
3886 loop_info->final_equiv_value = loop_info->final_value = 0;
3890 if (loop_dump_stream)
3891 fprintf (loop_dump_stream,
3892 "Loop iterations: Increment value can't be calculated.\n");
3896 if (GET_CODE (increment) != CONST_INT)
3898 /* If we have a REG, check to see if REG holds a constant value. */
3899 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3900 clear if it is worthwhile to try to handle such RTL. */
3901 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3902 increment = loop_find_equiv_value (loop, increment);
3904 if (GET_CODE (increment) != CONST_INT)
3906 if (loop_dump_stream)
3908 fprintf (loop_dump_stream,
3909 "Loop iterations: Increment value not constant ");
3910 print_rtl (loop_dump_stream, increment);
3911 fprintf (loop_dump_stream, ".\n");
3915 loop_info->increment = increment;
3918 if (GET_CODE (initial_value) != CONST_INT)
3920 if (loop_dump_stream)
3922 fprintf (loop_dump_stream,
3923 "Loop iterations: Initial value not constant ");
3924 print_rtl (loop_dump_stream, initial_value);
3925 fprintf (loop_dump_stream, ".\n");
3929 else if (comparison_code == EQ)
3931 if (loop_dump_stream)
3932 fprintf (loop_dump_stream,
3933 "Loop iterations: EQ comparison loop.\n");
3936 else if (GET_CODE (final_value) != CONST_INT)
3938 if (loop_dump_stream)
3940 fprintf (loop_dump_stream,
3941 "Loop iterations: Final value not constant ");
3942 print_rtl (loop_dump_stream, final_value);
3943 fprintf (loop_dump_stream, ".\n");
3948 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3951 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3952 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3953 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3954 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3956 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3957 - (INTVAL (final_value) < INTVAL (initial_value));
3959 if (INTVAL (increment) > 0)
3961 else if (INTVAL (increment) == 0)
3966 /* There are 27 different cases: compare_dir = -1, 0, 1;
3967 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3968 There are 4 normal cases, 4 reverse cases (where the iteration variable
3969 will overflow before the loop exits), 4 infinite loop cases, and 15
3970 immediate exit (0 or 1 iteration depending on loop type) cases.
3971 Only try to optimize the normal cases. */
3973 /* (compare_dir/final_larger/increment_dir)
3974 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3975 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3976 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3977 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3979 /* ?? If the meaning of reverse loops (where the iteration variable
3980 will overflow before the loop exits) is undefined, then could
3981 eliminate all of these special checks, and just always assume
3982 the loops are normal/immediate/infinite. Note that this means
3983 the sign of increment_dir does not have to be known. Also,
3984 since it does not really hurt if immediate exit loops or infinite loops
3985 are optimized, then that case could be ignored also, and hence all
3986 loops can be optimized.
3988 According to ANSI Spec, the reverse loop case result is undefined,
3989 because the action on overflow is undefined.
3991 See also the special test for NE loops below. */
3993 if (final_larger == increment_dir && final_larger != 0
3994 && (final_larger == compare_dir || compare_dir == 0))
3999 if (loop_dump_stream)
4000 fprintf (loop_dump_stream,
4001 "Loop iterations: Not normal loop.\n");
4005 /* Calculate the number of iterations, final_value is only an approximation,
4006 so correct for that. Note that abs_diff and n_iterations are
4007 unsigned, because they can be as large as 2^n - 1. */
4009 abs_inc = INTVAL (increment);
4011 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
4012 else if (abs_inc < 0)
4014 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
4020 /* For NE tests, make sure that the iteration variable won't miss
4021 the final value. If abs_diff mod abs_incr is not zero, then the
4022 iteration variable will overflow before the loop exits, and we
4023 can not calculate the number of iterations. */
4024 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4027 /* Note that the number of iterations could be calculated using
4028 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4029 handle potential overflow of the summation. */
4030 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4031 return loop_info->n_iterations;
4035 /* Replace uses of split bivs with their split pseudo register. This is
4036 for original instructions which remain after loop unrolling without
4040 remap_split_bivs (x)
4043 register enum rtx_code code;
4045 register const char *fmt;
4050 code = GET_CODE (x);
4065 /* If non-reduced/final-value givs were split, then this would also
4066 have to remap those givs also. */
4068 if (REGNO (x) < max_reg_before_loop
4069 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
4070 return reg_biv_class[REGNO (x)]->biv->src_reg;
4077 fmt = GET_RTX_FORMAT (code);
4078 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4081 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
4082 else if (fmt[i] == 'E')
4085 for (j = 0; j < XVECLEN (x, i); j++)
4086 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
4092 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4093 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4094 return 0. COPY_START is where we can start looking for the insns
4095 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4098 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4099 must dominate LAST_UID.
4101 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4102 may not dominate LAST_UID.
4104 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4105 must dominate LAST_UID. */
4108 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4115 int passed_jump = 0;
4116 rtx p = NEXT_INSN (copy_start);
4118 while (INSN_UID (p) != first_uid)
4120 if (GET_CODE (p) == JUMP_INSN)
4122 /* Could not find FIRST_UID. */
4128 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4129 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
4130 || ! dead_or_set_regno_p (p, regno))
4133 /* FIRST_UID is always executed. */
4134 if (passed_jump == 0)
4137 while (INSN_UID (p) != last_uid)
4139 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4140 can not be sure that FIRST_UID dominates LAST_UID. */
4141 if (GET_CODE (p) == CODE_LABEL)
4143 /* Could not find LAST_UID, but we reached the end of the loop, so
4145 else if (p == copy_end)
4150 /* FIRST_UID is always executed if LAST_UID is executed. */