1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 93, 94, 95, 97, 98, 1999 Free Software Foundation, Inc.
3 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* Try to unroll a loop, and split induction variables.
24 Loops for which the number of iterations can be calculated exactly are
25 handled specially. If the number of iterations times the insn_count is
26 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
27 Otherwise, we try to unroll the loop a number of times modulo the number
28 of iterations, so that only one exit test will be needed. It is unrolled
29 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
32 Otherwise, if the number of iterations can be calculated exactly at
33 run time, and the loop is always entered at the top, then we try to
34 precondition the loop. That is, at run time, calculate how many times
35 the loop will execute, and then execute the loop body a few times so
36 that the remaining iterations will be some multiple of 4 (or 2 if the
37 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
38 with only one exit test needed at the end of the loop.
40 Otherwise, if the number of iterations can not be calculated exactly,
41 not even at run time, then we still unroll the loop a number of times
42 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
43 but there must be an exit test after each copy of the loop body.
45 For each induction variable, which is dead outside the loop (replaceable)
46 or for which we can easily calculate the final value, if we can easily
47 calculate its value at each place where it is set as a function of the
48 current loop unroll count and the variable's value at loop entry, then
49 the induction variable is split into `N' different variables, one for
50 each copy of the loop body. One variable is live across the backward
51 branch, and the others are all calculated as a function of this variable.
52 This helps eliminate data dependencies, and leads to further opportunities
55 /* Possible improvements follow: */
57 /* ??? Add an extra pass somewhere to determine whether unrolling will
58 give any benefit. E.g. after generating all unrolled insns, compute the
59 cost of all insns and compare against cost of insns in rolled loop.
61 - On traditional architectures, unrolling a non-constant bound loop
62 is a win if there is a giv whose only use is in memory addresses, the
63 memory addresses can be split, and hence giv increments can be
65 - It is also a win if the loop is executed many times, and preconditioning
66 can be performed for the loop.
67 Add code to check for these and similar cases. */
69 /* ??? Improve control of which loops get unrolled. Could use profiling
70 info to only unroll the most commonly executed loops. Perhaps have
71 a user specifyable option to control the amount of code expansion,
72 or the percent of loops to consider for unrolling. Etc. */
74 /* ??? Look at the register copies inside the loop to see if they form a
75 simple permutation. If so, iterate the permutation until it gets back to
76 the start state. This is how many times we should unroll the loop, for
77 best results, because then all register copies can be eliminated.
78 For example, the lisp nreverse function should be unrolled 3 times
87 ??? The number of times to unroll the loop may also be based on data
88 references in the loop. For example, if we have a loop that references
89 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
91 /* ??? Add some simple linear equation solving capability so that we can
92 determine the number of loop iterations for more complex loops.
93 For example, consider this loop from gdb
94 #define SWAP_TARGET_AND_HOST(buffer,len)
97 char *p = (char *) buffer;
98 char *q = ((char *) buffer) + len - 1;
99 int iterations = (len + 1) >> 1;
101 for (p; p < q; p++, q--;)
109 start value = p = &buffer + current_iteration
110 end value = q = &buffer + len - 1 - current_iteration
111 Given the loop exit test of "p < q", then there must be "q - p" iterations,
112 set equal to zero and solve for number of iterations:
113 q - p = len - 1 - 2*current_iteration = 0
114 current_iteration = (len - 1) / 2
115 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
116 iterations of this loop. */
118 /* ??? Currently, no labels are marked as loop invariant when doing loop
119 unrolling. This is because an insn inside the loop, that loads the address
120 of a label inside the loop into a register, could be moved outside the loop
121 by the invariant code motion pass if labels were invariant. If the loop
122 is subsequently unrolled, the code will be wrong because each unrolled
123 body of the loop will use the same address, whereas each actually needs a
124 different address. A case where this happens is when a loop containing
125 a switch statement is unrolled.
127 It would be better to let labels be considered invariant. When we
128 unroll loops here, check to see if any insns using a label local to the
129 loop were moved before the loop. If so, then correct the problem, by
130 moving the insn back into the loop, or perhaps replicate the insn before
131 the loop, one copy for each time the loop is unrolled. */
133 /* The prime factors looked for when trying to unroll a loop by some
134 number which is modulo the total number of iterations. Just checking
135 for these 4 prime factors will find at least one factor for 75% of
136 all numbers theoretically. Practically speaking, this will succeed
137 almost all of the time since loops are generally a multiple of 2
140 #define NUM_FACTORS 4
142 struct _factor { int factor, count; } factors[NUM_FACTORS]
143 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
145 /* Describes the different types of loop unrolling performed. */
147 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
152 #include "insn-config.h"
153 #include "integrate.h"
161 /* This controls which loops are unrolled, and by how much we unroll
164 #ifndef MAX_UNROLLED_INSNS
165 #define MAX_UNROLLED_INSNS 100
168 /* Indexed by register number, if non-zero, then it contains a pointer
169 to a struct induction for a DEST_REG giv which has been combined with
170 one of more address givs. This is needed because whenever such a DEST_REG
171 giv is modified, we must modify the value of all split address givs
172 that were combined with this DEST_REG giv. */
174 static struct induction **addr_combined_regs;
176 /* Indexed by register number, if this is a splittable induction variable,
177 then this will hold the current value of the register, which depends on the
180 static rtx *splittable_regs;
182 /* Indexed by register number, if this is a splittable induction variable,
183 this indicates if it was made from a derived giv. */
184 static char *derived_regs;
186 /* Indexed by register number, if this is a splittable induction variable,
187 then this will hold the number of instructions in the loop that modify
188 the induction variable. Used to ensure that only the last insn modifying
189 a split iv will update the original iv of the dest. */
191 static int *splittable_regs_updates;
193 /* Forward declarations. */
195 static void init_reg_map PROTO((struct inline_remap *, int));
196 static rtx calculate_giv_inc PROTO((rtx, rtx, int));
197 static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
198 static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
199 static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
200 enum unroll_types, rtx, rtx, rtx, rtx));
201 static void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
202 static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int,
203 unsigned HOST_WIDE_INT));
204 static int find_splittable_givs PROTO((struct iv_class *, enum unroll_types,
205 rtx, rtx, rtx, int));
206 static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
207 static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
208 static int verify_addresses PROTO((struct induction *, rtx, int));
209 static rtx remap_split_bivs PROTO((rtx));
211 /* Try to unroll one loop and split induction variables in the loop.
213 The loop is described by the arguments LOOP_END, INSN_COUNT, and
214 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
215 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
216 indicates whether information generated in the strength reduction pass
219 This function is intended to be called from within `strength_reduce'
223 unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
224 loop_info, strength_reduce_p)
228 rtx end_insert_before;
229 struct loop_info *loop_info;
230 int strength_reduce_p;
233 int unroll_number = 1;
234 rtx copy_start, copy_end;
235 rtx insn, sequence, pattern, tem;
236 int max_labelno, max_insnno;
238 struct inline_remap *map;
245 int splitting_not_safe = 0;
246 enum unroll_types unroll_type;
247 int loop_preconditioned = 0;
249 /* This points to the last real insn in the loop, which should be either
250 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
254 /* Don't bother unrolling huge loops. Since the minimum factor is
255 two, loops greater than one half of MAX_UNROLLED_INSNS will never
257 if (insn_count > MAX_UNROLLED_INSNS / 2)
259 if (loop_dump_stream)
260 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
264 /* When emitting debugger info, we can't unroll loops with unequal numbers
265 of block_beg and block_end notes, because that would unbalance the block
266 structure of the function. This can happen as a result of the
267 "if (foo) bar; else break;" optimization in jump.c. */
268 /* ??? Gcc has a general policy that -g is never supposed to change the code
269 that the compiler emits, so we must disable this optimization always,
270 even if debug info is not being output. This is rare, so this should
271 not be a significant performance problem. */
273 if (1 /* write_symbols != NO_DEBUG */)
275 int block_begins = 0;
278 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
280 if (GET_CODE (insn) == NOTE)
282 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
284 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
289 if (block_begins != block_ends)
291 if (loop_dump_stream)
292 fprintf (loop_dump_stream,
293 "Unrolling failure: Unbalanced block notes.\n");
298 /* Determine type of unroll to perform. Depends on the number of iterations
299 and the size of the loop. */
301 /* If there is no strength reduce info, then set
302 loop_info->n_iterations to zero. This can happen if
303 strength_reduce can't find any bivs in the loop. A value of zero
304 indicates that the number of iterations could not be calculated. */
306 if (! strength_reduce_p)
307 loop_info->n_iterations = 0;
309 if (loop_dump_stream && loop_info->n_iterations > 0)
311 fputs ("Loop unrolling: ", loop_dump_stream);
312 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
313 loop_info->n_iterations);
314 fputs (" iterations.\n", loop_dump_stream);
317 /* Find and save a pointer to the last nonnote insn in the loop. */
319 last_loop_insn = prev_nonnote_insn (loop_end);
321 /* Calculate how many times to unroll the loop. Indicate whether or
322 not the loop is being completely unrolled. */
324 if (loop_info->n_iterations == 1)
326 /* If number of iterations is exactly 1, then eliminate the compare and
327 branch at the end of the loop since they will never be taken.
328 Then return, since no other action is needed here. */
330 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
331 don't do anything. */
333 if (GET_CODE (last_loop_insn) == BARRIER)
335 /* Delete the jump insn. This will delete the barrier also. */
336 delete_insn (PREV_INSN (last_loop_insn));
338 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
341 /* The immediately preceding insn is a compare which must be
343 delete_insn (last_loop_insn);
344 delete_insn (PREV_INSN (last_loop_insn));
346 /* The immediately preceding insn may not be the compare, so don't
348 delete_insn (last_loop_insn);
353 else if (loop_info->n_iterations > 0
354 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
356 unroll_number = loop_info->n_iterations;
357 unroll_type = UNROLL_COMPLETELY;
359 else if (loop_info->n_iterations > 0)
361 /* Try to factor the number of iterations. Don't bother with the
362 general case, only using 2, 3, 5, and 7 will get 75% of all
363 numbers theoretically, and almost all in practice. */
365 for (i = 0; i < NUM_FACTORS; i++)
366 factors[i].count = 0;
368 temp = loop_info->n_iterations;
369 for (i = NUM_FACTORS - 1; i >= 0; i--)
370 while (temp % factors[i].factor == 0)
373 temp = temp / factors[i].factor;
376 /* Start with the larger factors first so that we generally
377 get lots of unrolling. */
381 for (i = 3; i >= 0; i--)
382 while (factors[i].count--)
384 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
386 unroll_number *= factors[i].factor;
387 temp *= factors[i].factor;
393 /* If we couldn't find any factors, then unroll as in the normal
395 if (unroll_number == 1)
397 if (loop_dump_stream)
398 fprintf (loop_dump_stream,
399 "Loop unrolling: No factors found.\n");
402 unroll_type = UNROLL_MODULO;
406 /* Default case, calculate number of times to unroll loop based on its
408 if (unroll_number == 1)
410 if (8 * insn_count < MAX_UNROLLED_INSNS)
412 else if (4 * insn_count < MAX_UNROLLED_INSNS)
417 unroll_type = UNROLL_NAIVE;
420 /* Now we know how many times to unroll the loop. */
422 if (loop_dump_stream)
423 fprintf (loop_dump_stream,
424 "Unrolling loop %d times.\n", unroll_number);
427 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
429 /* Loops of these types can start with jump down to the exit condition
430 in rare circumstances.
432 Consider a pair of nested loops where the inner loop is part
433 of the exit code for the outer loop.
435 In this case jump.c will not duplicate the exit test for the outer
436 loop, so it will start with a jump to the exit code.
438 Then consider if the inner loop turns out to iterate once and
439 only once. We will end up deleting the jumps associated with
440 the inner loop. However, the loop notes are not removed from
441 the instruction stream.
443 And finally assume that we can compute the number of iterations
446 In this case unroll may want to unroll the outer loop even though
447 it starts with a jump to the outer loop's exit code.
449 We could try to optimize this case, but it hardly seems worth it.
450 Just return without unrolling the loop in such cases. */
453 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
454 insn = NEXT_INSN (insn);
455 if (GET_CODE (insn) == JUMP_INSN)
459 if (unroll_type == UNROLL_COMPLETELY)
461 /* Completely unrolling the loop: Delete the compare and branch at
462 the end (the last two instructions). This delete must done at the
463 very end of loop unrolling, to avoid problems with calls to
464 back_branch_in_range_p, which is called by find_splittable_regs.
465 All increments of splittable bivs/givs are changed to load constant
468 copy_start = loop_start;
470 /* Set insert_before to the instruction immediately after the JUMP_INSN
471 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
472 the loop will be correctly handled by copy_loop_body. */
473 insert_before = NEXT_INSN (last_loop_insn);
475 /* Set copy_end to the insn before the jump at the end of the loop. */
476 if (GET_CODE (last_loop_insn) == BARRIER)
477 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
478 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
481 /* The instruction immediately before the JUMP_INSN is a compare
482 instruction which we do not want to copy. */
483 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
485 /* The instruction immediately before the JUMP_INSN may not be the
486 compare, so we must copy it. */
487 copy_end = PREV_INSN (last_loop_insn);
492 /* We currently can't unroll a loop if it doesn't end with a
493 JUMP_INSN. There would need to be a mechanism that recognizes
494 this case, and then inserts a jump after each loop body, which
495 jumps to after the last loop body. */
496 if (loop_dump_stream)
497 fprintf (loop_dump_stream,
498 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
502 else if (unroll_type == UNROLL_MODULO)
504 /* Partially unrolling the loop: The compare and branch at the end
505 (the last two instructions) must remain. Don't copy the compare
506 and branch instructions at the end of the loop. Insert the unrolled
507 code immediately before the compare/branch at the end so that the
508 code will fall through to them as before. */
510 copy_start = loop_start;
512 /* Set insert_before to the jump insn at the end of the loop.
513 Set copy_end to before the jump insn at the end of the loop. */
514 if (GET_CODE (last_loop_insn) == BARRIER)
516 insert_before = PREV_INSN (last_loop_insn);
517 copy_end = PREV_INSN (insert_before);
519 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
522 /* The instruction immediately before the JUMP_INSN is a compare
523 instruction which we do not want to copy or delete. */
524 insert_before = PREV_INSN (last_loop_insn);
525 copy_end = PREV_INSN (insert_before);
527 /* The instruction immediately before the JUMP_INSN may not be the
528 compare, so we must copy it. */
529 insert_before = last_loop_insn;
530 copy_end = PREV_INSN (last_loop_insn);
535 /* We currently can't unroll a loop if it doesn't end with a
536 JUMP_INSN. There would need to be a mechanism that recognizes
537 this case, and then inserts a jump after each loop body, which
538 jumps to after the last loop body. */
539 if (loop_dump_stream)
540 fprintf (loop_dump_stream,
541 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
547 /* Normal case: Must copy the compare and branch instructions at the
550 if (GET_CODE (last_loop_insn) == BARRIER)
552 /* Loop ends with an unconditional jump and a barrier.
553 Handle this like above, don't copy jump and barrier.
554 This is not strictly necessary, but doing so prevents generating
555 unconditional jumps to an immediately following label.
557 This will be corrected below if the target of this jump is
558 not the start_label. */
560 insert_before = PREV_INSN (last_loop_insn);
561 copy_end = PREV_INSN (insert_before);
563 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
565 /* Set insert_before to immediately after the JUMP_INSN, so that
566 NOTEs at the end of the loop will be correctly handled by
568 insert_before = NEXT_INSN (last_loop_insn);
569 copy_end = last_loop_insn;
573 /* We currently can't unroll a loop if it doesn't end with a
574 JUMP_INSN. There would need to be a mechanism that recognizes
575 this case, and then inserts a jump after each loop body, which
576 jumps to after the last loop body. */
577 if (loop_dump_stream)
578 fprintf (loop_dump_stream,
579 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
583 /* If copying exit test branches because they can not be eliminated,
584 then must convert the fall through case of the branch to a jump past
585 the end of the loop. Create a label to emit after the loop and save
586 it for later use. Do not use the label after the loop, if any, since
587 it might be used by insns outside the loop, or there might be insns
588 added before it later by final_[bg]iv_value which must be after
589 the real exit label. */
590 exit_label = gen_label_rtx ();
593 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
594 insn = NEXT_INSN (insn);
596 if (GET_CODE (insn) == JUMP_INSN)
598 /* The loop starts with a jump down to the exit condition test.
599 Start copying the loop after the barrier following this
601 copy_start = NEXT_INSN (insn);
603 /* Splitting induction variables doesn't work when the loop is
604 entered via a jump to the bottom, because then we end up doing
605 a comparison against a new register for a split variable, but
606 we did not execute the set insn for the new register because
607 it was skipped over. */
608 splitting_not_safe = 1;
609 if (loop_dump_stream)
610 fprintf (loop_dump_stream,
611 "Splitting not safe, because loop not entered at top.\n");
614 copy_start = loop_start;
617 /* This should always be the first label in the loop. */
618 start_label = NEXT_INSN (copy_start);
619 /* There may be a line number note and/or a loop continue note here. */
620 while (GET_CODE (start_label) == NOTE)
621 start_label = NEXT_INSN (start_label);
622 if (GET_CODE (start_label) != CODE_LABEL)
624 /* This can happen as a result of jump threading. If the first insns in
625 the loop test the same condition as the loop's backward jump, or the
626 opposite condition, then the backward jump will be modified to point
627 to elsewhere, and the loop's start label is deleted.
629 This case currently can not be handled by the loop unrolling code. */
631 if (loop_dump_stream)
632 fprintf (loop_dump_stream,
633 "Unrolling failure: unknown insns between BEG note and loop label.\n");
636 if (LABEL_NAME (start_label))
638 /* The jump optimization pass must have combined the original start label
639 with a named label for a goto. We can't unroll this case because
640 jumps which go to the named label must be handled differently than
641 jumps to the loop start, and it is impossible to differentiate them
643 if (loop_dump_stream)
644 fprintf (loop_dump_stream,
645 "Unrolling failure: loop start label is gone\n");
649 if (unroll_type == UNROLL_NAIVE
650 && GET_CODE (last_loop_insn) == BARRIER
651 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
653 /* In this case, we must copy the jump and barrier, because they will
654 not be converted to jumps to an immediately following label. */
656 insert_before = NEXT_INSN (last_loop_insn);
657 copy_end = last_loop_insn;
660 if (unroll_type == UNROLL_NAIVE
661 && GET_CODE (last_loop_insn) == JUMP_INSN
662 && start_label != JUMP_LABEL (last_loop_insn))
664 /* ??? The loop ends with a conditional branch that does not branch back
665 to the loop start label. In this case, we must emit an unconditional
666 branch to the loop exit after emitting the final branch.
667 copy_loop_body does not have support for this currently, so we
668 give up. It doesn't seem worthwhile to unroll anyways since
669 unrolling would increase the number of branch instructions
671 if (loop_dump_stream)
672 fprintf (loop_dump_stream,
673 "Unrolling failure: final conditional branch not to loop start\n");
677 /* Allocate a translation table for the labels and insn numbers.
678 They will be filled in as we copy the insns in the loop. */
680 max_labelno = max_label_num ();
681 max_insnno = get_max_uid ();
683 map = (struct inline_remap *) alloca (sizeof (struct inline_remap));
685 map->integrating = 0;
686 map->const_equiv_varray = 0;
688 /* Allocate the label map. */
692 map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx));
694 local_label = (char *) alloca (max_labelno);
695 bzero (local_label, max_labelno);
700 /* Search the loop and mark all local labels, i.e. the ones which have to
701 be distinct labels when copied. For all labels which might be
702 non-local, set their label_map entries to point to themselves.
703 If they happen to be local their label_map entries will be overwritten
704 before the loop body is copied. The label_map entries for local labels
705 will be set to a different value each time the loop body is copied. */
707 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
711 if (GET_CODE (insn) == CODE_LABEL)
712 local_label[CODE_LABEL_NUMBER (insn)] = 1;
713 else if (GET_CODE (insn) == JUMP_INSN)
715 if (JUMP_LABEL (insn))
716 set_label_in_map (map,
717 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
719 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
720 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
722 rtx pat = PATTERN (insn);
723 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
724 int len = XVECLEN (pat, diff_vec_p);
727 for (i = 0; i < len; i++)
729 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
730 set_label_in_map (map,
731 CODE_LABEL_NUMBER (label),
736 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
737 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
741 /* Allocate space for the insn map. */
743 map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx));
745 /* Set this to zero, to indicate that we are doing loop unrolling,
746 not function inlining. */
747 map->inline_target = 0;
749 /* The register and constant maps depend on the number of registers
750 present, so the final maps can't be created until after
751 find_splittable_regs is called. However, they are needed for
752 preconditioning, so we create temporary maps when preconditioning
755 /* The preconditioning code may allocate two new pseudo registers. */
756 maxregnum = max_reg_num ();
758 /* Allocate and zero out the splittable_regs and addr_combined_regs
759 arrays. These must be zeroed here because they will be used if
760 loop preconditioning is performed, and must be zero for that case.
762 It is safe to do this here, since the extra registers created by the
763 preconditioning code and find_splittable_regs will never be used
764 to access the splittable_regs[] and addr_combined_regs[] arrays. */
766 splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx));
767 bzero ((char *) splittable_regs, maxregnum * sizeof (rtx));
768 derived_regs = alloca (maxregnum);
769 bzero (derived_regs, maxregnum);
770 splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int));
771 bzero ((char *) splittable_regs_updates, maxregnum * sizeof (int));
773 = (struct induction **) alloca (maxregnum * sizeof (struct induction *));
774 bzero ((char *) addr_combined_regs, maxregnum * sizeof (struct induction *));
775 local_regno = (char *) alloca (maxregnum);
776 bzero (local_regno, maxregnum);
778 /* Mark all local registers, i.e. the ones which are referenced only
780 if (INSN_UID (copy_end) < max_uid_for_loop)
782 int copy_start_luid = INSN_LUID (copy_start);
783 int copy_end_luid = INSN_LUID (copy_end);
785 /* If a register is used in the jump insn, we must not duplicate it
786 since it will also be used outside the loop. */
787 if (GET_CODE (copy_end) == JUMP_INSN)
789 /* If copy_start points to the NOTE that starts the loop, then we must
790 use the next luid, because invariant pseudo-regs moved out of the loop
791 have their lifetimes modified to start here, but they are not safe
793 if (copy_start == loop_start)
796 /* If a pseudo's lifetime is entirely contained within this loop, then we
797 can use a different pseudo in each unrolled copy of the loop. This
798 results in better code. */
799 /* We must limit the generic test to max_reg_before_loop, because only
800 these pseudo registers have valid regno_first_uid info. */
801 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
802 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
803 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
804 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
805 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
807 /* However, we must also check for loop-carried dependencies.
808 If the value the pseudo has at the end of iteration X is
809 used by iteration X+1, then we can not use a different pseudo
810 for each unrolled copy of the loop. */
811 /* A pseudo is safe if regno_first_uid is a set, and this
812 set dominates all instructions from regno_first_uid to
814 /* ??? This check is simplistic. We would get better code if
815 this check was more sophisticated. */
816 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
817 copy_start, copy_end))
820 if (loop_dump_stream)
823 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
825 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
829 /* Givs that have been created from multiple biv increments always have
831 for (j = first_increment_giv; j <= last_increment_giv; j++)
834 if (loop_dump_stream)
835 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
839 /* If this loop requires exit tests when unrolled, check to see if we
840 can precondition the loop so as to make the exit tests unnecessary.
841 Just like variable splitting, this is not safe if the loop is entered
842 via a jump to the bottom. Also, can not do this if no strength
843 reduce info, because precondition_loop_p uses this info. */
845 /* Must copy the loop body for preconditioning before the following
846 find_splittable_regs call since that will emit insns which need to
847 be after the preconditioned loop copies, but immediately before the
848 unrolled loop copies. */
850 /* Also, it is not safe to split induction variables for the preconditioned
851 copies of the loop body. If we split induction variables, then the code
852 assumes that each induction variable can be represented as a function
853 of its initial value and the loop iteration number. This is not true
854 in this case, because the last preconditioned copy of the loop body
855 could be any iteration from the first up to the `unroll_number-1'th,
856 depending on the initial value of the iteration variable. Therefore
857 we can not split induction variables here, because we can not calculate
858 their value. Hence, this code must occur before find_splittable_regs
861 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
863 rtx initial_value, final_value, increment;
864 enum machine_mode mode;
866 if (precondition_loop_p (loop_start, loop_info,
867 &initial_value, &final_value, &increment,
872 int abs_inc, neg_inc;
874 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
876 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
878 global_const_equiv_varray = map->const_equiv_varray;
880 init_reg_map (map, maxregnum);
882 /* Limit loop unrolling to 4, since this will make 7 copies of
884 if (unroll_number > 4)
887 /* Save the absolute value of the increment, and also whether or
888 not it is negative. */
890 abs_inc = INTVAL (increment);
899 /* Calculate the difference between the final and initial values.
900 Final value may be a (plus (reg x) (const_int 1)) rtx.
901 Let the following cse pass simplify this if initial value is
904 We must copy the final and initial values here to avoid
905 improperly shared rtl. */
907 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
908 copy_rtx (initial_value), NULL_RTX, 0,
911 /* Now calculate (diff % (unroll * abs (increment))) by using an
913 diff = expand_binop (GET_MODE (diff), and_optab, diff,
914 GEN_INT (unroll_number * abs_inc - 1),
915 NULL_RTX, 0, OPTAB_LIB_WIDEN);
917 /* Now emit a sequence of branches to jump to the proper precond
920 labels = (rtx *) alloca (sizeof (rtx) * unroll_number);
921 for (i = 0; i < unroll_number; i++)
922 labels[i] = gen_label_rtx ();
924 /* Check for the case where the initial value is greater than or
925 equal to the final value. In that case, we want to execute
926 exactly one loop iteration. The code below will fail for this
927 case. This check does not apply if the loop has a NE
928 comparison at the end. */
930 if (loop_info->comparison_code != NE)
932 emit_cmp_and_jump_insns (initial_value, final_value,
934 NULL_RTX, mode, 0, 0, labels[1]);
935 JUMP_LABEL (get_last_insn ()) = labels[1];
936 LABEL_NUSES (labels[1])++;
939 /* Assuming the unroll_number is 4, and the increment is 2, then
940 for a negative increment: for a positive increment:
941 diff = 0,1 precond 0 diff = 0,7 precond 0
942 diff = 2,3 precond 3 diff = 1,2 precond 1
943 diff = 4,5 precond 2 diff = 3,4 precond 2
944 diff = 6,7 precond 1 diff = 5,6 precond 3 */
946 /* We only need to emit (unroll_number - 1) branches here, the
947 last case just falls through to the following code. */
949 /* ??? This would give better code if we emitted a tree of branches
950 instead of the current linear list of branches. */
952 for (i = 0; i < unroll_number - 1; i++)
955 enum rtx_code cmp_code;
957 /* For negative increments, must invert the constant compared
958 against, except when comparing against zero. */
966 cmp_const = unroll_number - i;
975 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
976 cmp_code, NULL_RTX, mode, 0, 0,
978 JUMP_LABEL (get_last_insn ()) = labels[i];
979 LABEL_NUSES (labels[i])++;
982 /* If the increment is greater than one, then we need another branch,
983 to handle other cases equivalent to 0. */
985 /* ??? This should be merged into the code above somehow to help
986 simplify the code here, and reduce the number of branches emitted.
987 For the negative increment case, the branch here could easily
988 be merged with the `0' case branch above. For the positive
989 increment case, it is not clear how this can be simplified. */
994 enum rtx_code cmp_code;
998 cmp_const = abs_inc - 1;
1003 cmp_const = abs_inc * (unroll_number - 1) + 1;
1007 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1008 NULL_RTX, mode, 0, 0, labels[0]);
1009 JUMP_LABEL (get_last_insn ()) = labels[0];
1010 LABEL_NUSES (labels[0])++;
1013 sequence = gen_sequence ();
1015 emit_insn_before (sequence, loop_start);
1017 /* Only the last copy of the loop body here needs the exit
1018 test, so set copy_end to exclude the compare/branch here,
1019 and then reset it inside the loop when get to the last
1022 if (GET_CODE (last_loop_insn) == BARRIER)
1023 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1024 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1027 /* The immediately preceding insn is a compare which we do not
1029 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1031 /* The immediately preceding insn may not be a compare, so we
1033 copy_end = PREV_INSN (last_loop_insn);
1039 for (i = 1; i < unroll_number; i++)
1041 emit_label_after (labels[unroll_number - i],
1042 PREV_INSN (loop_start));
1044 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1045 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1046 (VARRAY_SIZE (map->const_equiv_varray)
1047 * sizeof (struct const_equiv_data)));
1050 for (j = 0; j < max_labelno; j++)
1052 set_label_in_map (map, j, gen_label_rtx ());
1054 for (j = FIRST_PSEUDO_REGISTER; j < maxregnum; j++)
1057 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1058 record_base_value (REGNO (map->reg_map[j]),
1059 regno_reg_rtx[j], 0);
1061 /* The last copy needs the compare/branch insns at the end,
1062 so reset copy_end here if the loop ends with a conditional
1065 if (i == unroll_number - 1)
1067 if (GET_CODE (last_loop_insn) == BARRIER)
1068 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1070 copy_end = last_loop_insn;
1073 /* None of the copies are the `last_iteration', so just
1074 pass zero for that parameter. */
1075 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1076 unroll_type, start_label, loop_end,
1077 loop_start, copy_end);
1079 emit_label_after (labels[0], PREV_INSN (loop_start));
1081 if (GET_CODE (last_loop_insn) == BARRIER)
1083 insert_before = PREV_INSN (last_loop_insn);
1084 copy_end = PREV_INSN (insert_before);
1089 /* The immediately preceding insn is a compare which we do not
1091 insert_before = PREV_INSN (last_loop_insn);
1092 copy_end = PREV_INSN (insert_before);
1094 /* The immediately preceding insn may not be a compare, so we
1096 insert_before = last_loop_insn;
1097 copy_end = PREV_INSN (last_loop_insn);
1101 /* Set unroll type to MODULO now. */
1102 unroll_type = UNROLL_MODULO;
1103 loop_preconditioned = 1;
1107 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1108 the loop unless all loops are being unrolled. */
1109 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1111 if (loop_dump_stream)
1112 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1116 /* At this point, we are guaranteed to unroll the loop. */
1118 /* Keep track of the unroll factor for the loop. */
1119 if (unroll_type == UNROLL_COMPLETELY)
1120 loop_info->unroll_number = -1;
1122 loop_info->unroll_number = unroll_number;
1125 /* For each biv and giv, determine whether it can be safely split into
1126 a different variable for each unrolled copy of the loop body.
1127 We precalculate and save this info here, since computing it is
1130 Do this before deleting any instructions from the loop, so that
1131 back_branch_in_range_p will work correctly. */
1133 if (splitting_not_safe)
1136 temp = find_splittable_regs (unroll_type, loop_start, loop_end,
1137 end_insert_before, unroll_number,
1138 loop_info->n_iterations);
1140 /* find_splittable_regs may have created some new registers, so must
1141 reallocate the reg_map with the new larger size, and must realloc
1142 the constant maps also. */
1144 maxregnum = max_reg_num ();
1145 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
1147 init_reg_map (map, maxregnum);
1149 if (map->const_equiv_varray == 0)
1150 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1151 maxregnum + temp * unroll_number * 2,
1153 global_const_equiv_varray = map->const_equiv_varray;
1155 /* Search the list of bivs and givs to find ones which need to be remapped
1156 when split, and set their reg_map entry appropriately. */
1158 for (bl = loop_iv_list; bl; bl = bl->next)
1160 if (REGNO (bl->biv->src_reg) != bl->regno)
1161 map->reg_map[bl->regno] = bl->biv->src_reg;
1163 /* Currently, non-reduced/final-value givs are never split. */
1164 for (v = bl->giv; v; v = v->next_iv)
1165 if (REGNO (v->src_reg) != bl->regno)
1166 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1170 /* Use our current register alignment and pointer flags. */
1171 map->regno_pointer_flag = regno_pointer_flag;
1172 map->regno_pointer_align = regno_pointer_align;
1174 /* If the loop is being partially unrolled, and the iteration variables
1175 are being split, and are being renamed for the split, then must fix up
1176 the compare/jump instruction at the end of the loop to refer to the new
1177 registers. This compare isn't copied, so the registers used in it
1178 will never be replaced if it isn't done here. */
1180 if (unroll_type == UNROLL_MODULO)
1182 insn = NEXT_INSN (copy_end);
1183 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1184 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1187 /* For unroll_number times, make a copy of each instruction
1188 between copy_start and copy_end, and insert these new instructions
1189 before the end of the loop. */
1191 for (i = 0; i < unroll_number; i++)
1193 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1194 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1195 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1198 for (j = 0; j < max_labelno; j++)
1200 set_label_in_map (map, j, gen_label_rtx ());
1202 for (j = FIRST_PSEUDO_REGISTER; j < maxregnum; j++)
1205 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1206 record_base_value (REGNO (map->reg_map[j]),
1207 regno_reg_rtx[j], 0);
1210 /* If loop starts with a branch to the test, then fix it so that
1211 it points to the test of the first unrolled copy of the loop. */
1212 if (i == 0 && loop_start != copy_start)
1214 insn = PREV_INSN (copy_start);
1215 pattern = PATTERN (insn);
1217 tem = get_label_from_map (map,
1219 (XEXP (SET_SRC (pattern), 0)));
1220 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1222 /* Set the jump label so that it can be used by later loop unrolling
1224 JUMP_LABEL (insn) = tem;
1225 LABEL_NUSES (tem)++;
1228 copy_loop_body (copy_start, copy_end, map, exit_label,
1229 i == unroll_number - 1, unroll_type, start_label,
1230 loop_end, insert_before, insert_before);
1233 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1234 insn to be deleted. This prevents any runaway delete_insn call from
1235 more insns that it should, as it always stops at a CODE_LABEL. */
1237 /* Delete the compare and branch at the end of the loop if completely
1238 unrolling the loop. Deleting the backward branch at the end also
1239 deletes the code label at the start of the loop. This is done at
1240 the very end to avoid problems with back_branch_in_range_p. */
1242 if (unroll_type == UNROLL_COMPLETELY)
1243 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1245 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1247 /* Delete all of the original loop instructions. Don't delete the
1248 LOOP_BEG note, or the first code label in the loop. */
1250 insn = NEXT_INSN (copy_start);
1251 while (insn != safety_label)
1253 if (insn != start_label)
1254 insn = delete_insn (insn);
1256 insn = NEXT_INSN (insn);
1259 /* Can now delete the 'safety' label emitted to protect us from runaway
1260 delete_insn calls. */
1261 if (INSN_DELETED_P (safety_label))
1263 delete_insn (safety_label);
1265 /* If exit_label exists, emit it after the loop. Doing the emit here
1266 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1267 This is needed so that mostly_true_jump in reorg.c will treat jumps
1268 to this loop end label correctly, i.e. predict that they are usually
1271 emit_label_after (exit_label, loop_end);
1274 if (map && map->const_equiv_varray)
1275 VARRAY_FREE (map->const_equiv_varray);
1278 /* Return true if the loop can be safely, and profitably, preconditioned
1279 so that the unrolled copies of the loop body don't need exit tests.
1281 This only works if final_value, initial_value and increment can be
1282 determined, and if increment is a constant power of 2.
1283 If increment is not a power of 2, then the preconditioning modulo
1284 operation would require a real modulo instead of a boolean AND, and this
1285 is not considered `profitable'. */
1287 /* ??? If the loop is known to be executed very many times, or the machine
1288 has a very cheap divide instruction, then preconditioning is a win even
1289 when the increment is not a power of 2. Use RTX_COST to compute
1290 whether divide is cheap.
1291 ??? A divide by constant doesn't actually need a divide, look at
1292 expand_divmod. The reduced cost of this optimized modulo is not
1293 reflected in RTX_COST. */
1296 precondition_loop_p (loop_start, loop_info,
1297 initial_value, final_value, increment, mode)
1299 struct loop_info *loop_info;
1300 rtx *initial_value, *final_value, *increment;
1301 enum machine_mode *mode;
1304 if (loop_info->n_iterations > 0)
1306 *initial_value = const0_rtx;
1307 *increment = const1_rtx;
1308 *final_value = GEN_INT (loop_info->n_iterations);
1311 if (loop_dump_stream)
1313 fputs ("Preconditioning: Success, number of iterations known, ",
1315 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1316 loop_info->n_iterations);
1317 fputs (".\n", loop_dump_stream);
1322 if (loop_info->initial_value == 0)
1324 if (loop_dump_stream)
1325 fprintf (loop_dump_stream,
1326 "Preconditioning: Could not find initial value.\n");
1329 else if (loop_info->increment == 0)
1331 if (loop_dump_stream)
1332 fprintf (loop_dump_stream,
1333 "Preconditioning: Could not find increment value.\n");
1336 else if (GET_CODE (loop_info->increment) != CONST_INT)
1338 if (loop_dump_stream)
1339 fprintf (loop_dump_stream,
1340 "Preconditioning: Increment not a constant.\n");
1343 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1344 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1346 if (loop_dump_stream)
1347 fprintf (loop_dump_stream,
1348 "Preconditioning: Increment not a constant power of 2.\n");
1352 /* Unsigned_compare and compare_dir can be ignored here, since they do
1353 not matter for preconditioning. */
1355 if (loop_info->final_value == 0)
1357 if (loop_dump_stream)
1358 fprintf (loop_dump_stream,
1359 "Preconditioning: EQ comparison loop.\n");
1363 /* Must ensure that final_value is invariant, so call invariant_p to
1364 check. Before doing so, must check regno against max_reg_before_loop
1365 to make sure that the register is in the range covered by invariant_p.
1366 If it isn't, then it is most likely a biv/giv which by definition are
1368 if ((GET_CODE (loop_info->final_value) == REG
1369 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1370 || (GET_CODE (loop_info->final_value) == PLUS
1371 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1372 || ! invariant_p (loop_info->final_value))
1374 if (loop_dump_stream)
1375 fprintf (loop_dump_stream,
1376 "Preconditioning: Final value not invariant.\n");
1380 /* Fail for floating point values, since the caller of this function
1381 does not have code to deal with them. */
1382 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1383 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1385 if (loop_dump_stream)
1386 fprintf (loop_dump_stream,
1387 "Preconditioning: Floating point final or initial value.\n");
1391 /* Fail if loop_info->iteration_var is not live before loop_start,
1392 since we need to test its value in the preconditioning code. */
1394 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1395 > INSN_LUID (loop_start))
1397 if (loop_dump_stream)
1398 fprintf (loop_dump_stream,
1399 "Preconditioning: Iteration var not live before loop start.\n");
1403 /* ??? Note that if iteration_info is modifed to allow GIV iterators
1404 such as "while (i-- > 0)", the initial value will be one too small.
1405 In this case, loop_iteration_var could be used to determine
1406 the correct initial value, provided the loop has not been reversed.
1408 Also note that the absolute values of initial_value and
1409 final_value are unimportant as only their difference is used for
1410 calculating the number of loop iterations. */
1411 *initial_value = loop_info->initial_value;
1412 *increment = loop_info->increment;
1413 *final_value = loop_info->final_value;
1415 /* Decide what mode to do these calculations in. Choose the larger
1416 of final_value's mode and initial_value's mode, or a full-word if
1417 both are constants. */
1418 *mode = GET_MODE (*final_value);
1419 if (*mode == VOIDmode)
1421 *mode = GET_MODE (*initial_value);
1422 if (*mode == VOIDmode)
1425 else if (*mode != GET_MODE (*initial_value)
1426 && (GET_MODE_SIZE (*mode)
1427 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1428 *mode = GET_MODE (*initial_value);
1431 if (loop_dump_stream)
1432 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1437 /* All pseudo-registers must be mapped to themselves. Two hard registers
1438 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1439 REGNUM, to avoid function-inlining specific conversions of these
1440 registers. All other hard regs can not be mapped because they may be
1445 init_reg_map (map, maxregnum)
1446 struct inline_remap *map;
1451 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1452 map->reg_map[i] = regno_reg_rtx[i];
1453 /* Just clear the rest of the entries. */
1454 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1455 map->reg_map[i] = 0;
1457 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1458 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1459 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1460 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1463 /* Strength-reduction will often emit code for optimized biv/givs which
1464 calculates their value in a temporary register, and then copies the result
1465 to the iv. This procedure reconstructs the pattern computing the iv;
1466 verifying that all operands are of the proper form.
1468 PATTERN must be the result of single_set.
1469 The return value is the amount that the giv is incremented by. */
1472 calculate_giv_inc (pattern, src_insn, regno)
1473 rtx pattern, src_insn;
1477 rtx increment_total = 0;
1481 /* Verify that we have an increment insn here. First check for a plus
1482 as the set source. */
1483 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1485 /* SR sometimes computes the new giv value in a temp, then copies it
1487 src_insn = PREV_INSN (src_insn);
1488 pattern = PATTERN (src_insn);
1489 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1492 /* The last insn emitted is not needed, so delete it to avoid confusing
1493 the second cse pass. This insn sets the giv unnecessarily. */
1494 delete_insn (get_last_insn ());
1497 /* Verify that we have a constant as the second operand of the plus. */
1498 increment = XEXP (SET_SRC (pattern), 1);
1499 if (GET_CODE (increment) != CONST_INT)
1501 /* SR sometimes puts the constant in a register, especially if it is
1502 too big to be an add immed operand. */
1503 src_insn = PREV_INSN (src_insn);
1504 increment = SET_SRC (PATTERN (src_insn));
1506 /* SR may have used LO_SUM to compute the constant if it is too large
1507 for a load immed operand. In this case, the constant is in operand
1508 one of the LO_SUM rtx. */
1509 if (GET_CODE (increment) == LO_SUM)
1510 increment = XEXP (increment, 1);
1512 /* Some ports store large constants in memory and add a REG_EQUAL
1513 note to the store insn. */
1514 else if (GET_CODE (increment) == MEM)
1516 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1518 increment = XEXP (note, 0);
1521 else if (GET_CODE (increment) == IOR
1522 || GET_CODE (increment) == ASHIFT
1523 || GET_CODE (increment) == PLUS)
1525 /* The rs6000 port loads some constants with IOR.
1526 The alpha port loads some constants with ASHIFT and PLUS. */
1527 rtx second_part = XEXP (increment, 1);
1528 enum rtx_code code = GET_CODE (increment);
1530 src_insn = PREV_INSN (src_insn);
1531 increment = SET_SRC (PATTERN (src_insn));
1532 /* Don't need the last insn anymore. */
1533 delete_insn (get_last_insn ());
1535 if (GET_CODE (second_part) != CONST_INT
1536 || GET_CODE (increment) != CONST_INT)
1540 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1541 else if (code == PLUS)
1542 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1544 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1547 if (GET_CODE (increment) != CONST_INT)
1550 /* The insn loading the constant into a register is no longer needed,
1552 delete_insn (get_last_insn ());
1555 if (increment_total)
1556 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1558 increment_total = increment;
1560 /* Check that the source register is the same as the register we expected
1561 to see as the source. If not, something is seriously wrong. */
1562 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1563 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1565 /* Some machines (e.g. the romp), may emit two add instructions for
1566 certain constants, so lets try looking for another add immediately
1567 before this one if we have only seen one add insn so far. */
1573 src_insn = PREV_INSN (src_insn);
1574 pattern = PATTERN (src_insn);
1576 delete_insn (get_last_insn ());
1584 return increment_total;
1587 /* Copy REG_NOTES, except for insn references, because not all insn_map
1588 entries are valid yet. We do need to copy registers now though, because
1589 the reg_map entries can change during copying. */
1592 initial_reg_note_copy (notes, map)
1594 struct inline_remap *map;
1601 copy = rtx_alloc (GET_CODE (notes));
1602 PUT_MODE (copy, GET_MODE (notes));
1604 if (GET_CODE (notes) == EXPR_LIST)
1605 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map);
1606 else if (GET_CODE (notes) == INSN_LIST)
1607 /* Don't substitute for these yet. */
1608 XEXP (copy, 0) = XEXP (notes, 0);
1612 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1617 /* Fixup insn references in copied REG_NOTES. */
1620 final_reg_note_copy (notes, map)
1622 struct inline_remap *map;
1626 for (note = notes; note; note = XEXP (note, 1))
1627 if (GET_CODE (note) == INSN_LIST)
1628 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1631 /* Copy each instruction in the loop, substituting from map as appropriate.
1632 This is very similar to a loop in expand_inline_function. */
1635 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1636 unroll_type, start_label, loop_end, insert_before,
1638 rtx copy_start, copy_end;
1639 struct inline_remap *map;
1642 enum unroll_types unroll_type;
1643 rtx start_label, loop_end, insert_before, copy_notes_from;
1647 int dest_reg_was_split, i;
1651 rtx final_label = 0;
1652 rtx giv_inc, giv_dest_reg, giv_src_reg;
1654 /* If this isn't the last iteration, then map any references to the
1655 start_label to final_label. Final label will then be emitted immediately
1656 after the end of this loop body if it was ever used.
1658 If this is the last iteration, then map references to the start_label
1660 if (! last_iteration)
1662 final_label = gen_label_rtx ();
1663 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1667 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1674 insn = NEXT_INSN (insn);
1676 map->orig_asm_operands_vector = 0;
1678 switch (GET_CODE (insn))
1681 pattern = PATTERN (insn);
1685 /* Check to see if this is a giv that has been combined with
1686 some split address givs. (Combined in the sense that
1687 `combine_givs' in loop.c has put two givs in the same register.)
1688 In this case, we must search all givs based on the same biv to
1689 find the address givs. Then split the address givs.
1690 Do this before splitting the giv, since that may map the
1691 SET_DEST to a new register. */
1693 if ((set = single_set (insn))
1694 && GET_CODE (SET_DEST (set)) == REG
1695 && addr_combined_regs[REGNO (SET_DEST (set))])
1697 struct iv_class *bl;
1698 struct induction *v, *tv;
1699 int regno = REGNO (SET_DEST (set));
1701 v = addr_combined_regs[REGNO (SET_DEST (set))];
1702 bl = reg_biv_class[REGNO (v->src_reg)];
1704 /* Although the giv_inc amount is not needed here, we must call
1705 calculate_giv_inc here since it might try to delete the
1706 last insn emitted. If we wait until later to call it,
1707 we might accidentally delete insns generated immediately
1708 below by emit_unrolled_add. */
1710 if (! derived_regs[regno])
1711 giv_inc = calculate_giv_inc (set, insn, regno);
1713 /* Now find all address giv's that were combined with this
1715 for (tv = bl->giv; tv; tv = tv->next_iv)
1716 if (tv->giv_type == DEST_ADDR && tv->same == v)
1720 /* If this DEST_ADDR giv was not split, then ignore it. */
1721 if (*tv->location != tv->dest_reg)
1724 /* Scale this_giv_inc if the multiplicative factors of
1725 the two givs are different. */
1726 this_giv_inc = INTVAL (giv_inc);
1727 if (tv->mult_val != v->mult_val)
1728 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1729 * INTVAL (tv->mult_val));
1731 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1732 *tv->location = tv->dest_reg;
1734 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1736 /* Must emit an insn to increment the split address
1737 giv. Add in the const_adjust field in case there
1738 was a constant eliminated from the address. */
1739 rtx value, dest_reg;
1741 /* tv->dest_reg will be either a bare register,
1742 or else a register plus a constant. */
1743 if (GET_CODE (tv->dest_reg) == REG)
1744 dest_reg = tv->dest_reg;
1746 dest_reg = XEXP (tv->dest_reg, 0);
1748 /* Check for shared address givs, and avoid
1749 incrementing the shared pseudo reg more than
1751 if (! tv->same_insn && ! tv->shared)
1753 /* tv->dest_reg may actually be a (PLUS (REG)
1754 (CONST)) here, so we must call plus_constant
1755 to add the const_adjust amount before calling
1756 emit_unrolled_add below. */
1757 value = plus_constant (tv->dest_reg,
1760 /* The constant could be too large for an add
1761 immediate, so can't directly emit an insn
1763 emit_unrolled_add (dest_reg, XEXP (value, 0),
1767 /* Reset the giv to be just the register again, in case
1768 it is used after the set we have just emitted.
1769 We must subtract the const_adjust factor added in
1771 tv->dest_reg = plus_constant (dest_reg,
1772 - tv->const_adjust);
1773 *tv->location = tv->dest_reg;
1778 /* If this is a setting of a splittable variable, then determine
1779 how to split the variable, create a new set based on this split,
1780 and set up the reg_map so that later uses of the variable will
1781 use the new split variable. */
1783 dest_reg_was_split = 0;
1785 if ((set = single_set (insn))
1786 && GET_CODE (SET_DEST (set)) == REG
1787 && splittable_regs[REGNO (SET_DEST (set))])
1789 int regno = REGNO (SET_DEST (set));
1792 dest_reg_was_split = 1;
1794 giv_dest_reg = SET_DEST (set);
1795 if (derived_regs[regno])
1797 /* ??? This relies on SET_SRC (SET) to be of
1798 the form (plus (reg) (const_int)), and thus
1799 forces recombine_givs to restrict the kind
1800 of giv derivations it does before unrolling. */
1801 giv_src_reg = XEXP (SET_SRC (set), 0);
1802 giv_inc = XEXP (SET_SRC (set), 1);
1806 giv_src_reg = giv_dest_reg;
1807 /* Compute the increment value for the giv, if it wasn't
1808 already computed above. */
1810 giv_inc = calculate_giv_inc (set, insn, regno);
1812 src_regno = REGNO (giv_src_reg);
1814 if (unroll_type == UNROLL_COMPLETELY)
1816 /* Completely unrolling the loop. Set the induction
1817 variable to a known constant value. */
1819 /* The value in splittable_regs may be an invariant
1820 value, so we must use plus_constant here. */
1821 splittable_regs[regno]
1822 = plus_constant (splittable_regs[src_regno],
1825 if (GET_CODE (splittable_regs[regno]) == PLUS)
1827 giv_src_reg = XEXP (splittable_regs[regno], 0);
1828 giv_inc = XEXP (splittable_regs[regno], 1);
1832 /* The splittable_regs value must be a REG or a
1833 CONST_INT, so put the entire value in the giv_src_reg
1835 giv_src_reg = splittable_regs[regno];
1836 giv_inc = const0_rtx;
1841 /* Partially unrolling loop. Create a new pseudo
1842 register for the iteration variable, and set it to
1843 be a constant plus the original register. Except
1844 on the last iteration, when the result has to
1845 go back into the original iteration var register. */
1847 /* Handle bivs which must be mapped to a new register
1848 when split. This happens for bivs which need their
1849 final value set before loop entry. The new register
1850 for the biv was stored in the biv's first struct
1851 induction entry by find_splittable_regs. */
1853 if (regno < max_reg_before_loop
1854 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1856 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1857 giv_dest_reg = giv_src_reg;
1861 /* If non-reduced/final-value givs were split, then
1862 this would have to remap those givs also. See
1863 find_splittable_regs. */
1866 splittable_regs[regno]
1867 = GEN_INT (INTVAL (giv_inc)
1868 + INTVAL (splittable_regs[src_regno]));
1869 giv_inc = splittable_regs[regno];
1871 /* Now split the induction variable by changing the dest
1872 of this insn to a new register, and setting its
1873 reg_map entry to point to this new register.
1875 If this is the last iteration, and this is the last insn
1876 that will update the iv, then reuse the original dest,
1877 to ensure that the iv will have the proper value when
1878 the loop exits or repeats.
1880 Using splittable_regs_updates here like this is safe,
1881 because it can only be greater than one if all
1882 instructions modifying the iv are always executed in
1885 if (! last_iteration
1886 || (splittable_regs_updates[regno]-- != 1))
1888 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1890 map->reg_map[regno] = tem;
1891 record_base_value (REGNO (tem),
1892 giv_inc == const0_rtx
1894 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1895 giv_src_reg, giv_inc),
1899 map->reg_map[regno] = giv_src_reg;
1902 /* The constant being added could be too large for an add
1903 immediate, so can't directly emit an insn here. */
1904 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1905 copy = get_last_insn ();
1906 pattern = PATTERN (copy);
1910 pattern = copy_rtx_and_substitute (pattern, map);
1911 copy = emit_insn (pattern);
1913 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1916 /* If this insn is setting CC0, it may need to look at
1917 the insn that uses CC0 to see what type of insn it is.
1918 In that case, the call to recog via validate_change will
1919 fail. So don't substitute constants here. Instead,
1920 do it when we emit the following insn.
1922 For example, see the pyr.md file. That machine has signed and
1923 unsigned compares. The compare patterns must check the
1924 following branch insn to see which what kind of compare to
1927 If the previous insn set CC0, substitute constants on it as
1929 if (sets_cc0_p (PATTERN (copy)) != 0)
1934 try_constants (cc0_insn, map);
1936 try_constants (copy, map);
1939 try_constants (copy, map);
1942 /* Make split induction variable constants `permanent' since we
1943 know there are no backward branches across iteration variable
1944 settings which would invalidate this. */
1945 if (dest_reg_was_split)
1947 int regno = REGNO (SET_DEST (pattern));
1949 if (regno < VARRAY_SIZE (map->const_equiv_varray)
1950 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
1952 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
1957 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
1958 copy = emit_jump_insn (pattern);
1959 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1961 if (JUMP_LABEL (insn) == start_label && insn == copy_end
1962 && ! last_iteration)
1964 /* This is a branch to the beginning of the loop; this is the
1965 last insn being copied; and this is not the last iteration.
1966 In this case, we want to change the original fall through
1967 case to be a branch past the end of the loop, and the
1968 original jump label case to fall_through. */
1970 if (invert_exp (pattern, copy))
1972 if (! redirect_exp (&pattern,
1973 get_label_from_map (map,
1975 (JUMP_LABEL (insn))),
1982 rtx lab = gen_label_rtx ();
1983 /* Can't do it by reversing the jump (probably because we
1984 couldn't reverse the conditions), so emit a new
1985 jump_insn after COPY, and redirect the jump around
1987 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
1988 jmp = emit_barrier_after (jmp);
1989 emit_label_after (lab, jmp);
1990 LABEL_NUSES (lab) = 0;
1991 if (! redirect_exp (&pattern,
1992 get_label_from_map (map,
1994 (JUMP_LABEL (insn))),
2002 try_constants (cc0_insn, map);
2005 try_constants (copy, map);
2007 /* Set the jump label of COPY correctly to avoid problems with
2008 later passes of unroll_loop, if INSN had jump label set. */
2009 if (JUMP_LABEL (insn))
2013 /* Can't use the label_map for every insn, since this may be
2014 the backward branch, and hence the label was not mapped. */
2015 if ((set = single_set (copy)))
2017 tem = SET_SRC (set);
2018 if (GET_CODE (tem) == LABEL_REF)
2019 label = XEXP (tem, 0);
2020 else if (GET_CODE (tem) == IF_THEN_ELSE)
2022 if (XEXP (tem, 1) != pc_rtx)
2023 label = XEXP (XEXP (tem, 1), 0);
2025 label = XEXP (XEXP (tem, 2), 0);
2029 if (label && GET_CODE (label) == CODE_LABEL)
2030 JUMP_LABEL (copy) = label;
2033 /* An unrecognizable jump insn, probably the entry jump
2034 for a switch statement. This label must have been mapped,
2035 so just use the label_map to get the new jump label. */
2037 = get_label_from_map (map,
2038 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2041 /* If this is a non-local jump, then must increase the label
2042 use count so that the label will not be deleted when the
2043 original jump is deleted. */
2044 LABEL_NUSES (JUMP_LABEL (copy))++;
2046 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2047 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2049 rtx pat = PATTERN (copy);
2050 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2051 int len = XVECLEN (pat, diff_vec_p);
2054 for (i = 0; i < len; i++)
2055 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2058 /* If this used to be a conditional jump insn but whose branch
2059 direction is now known, we must do something special. */
2060 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2063 /* The previous insn set cc0 for us. So delete it. */
2064 delete_insn (PREV_INSN (copy));
2067 /* If this is now a no-op, delete it. */
2068 if (map->last_pc_value == pc_rtx)
2070 /* Don't let delete_insn delete the label referenced here,
2071 because we might possibly need it later for some other
2072 instruction in the loop. */
2073 if (JUMP_LABEL (copy))
2074 LABEL_NUSES (JUMP_LABEL (copy))++;
2076 if (JUMP_LABEL (copy))
2077 LABEL_NUSES (JUMP_LABEL (copy))--;
2081 /* Otherwise, this is unconditional jump so we must put a
2082 BARRIER after it. We could do some dead code elimination
2083 here, but jump.c will do it just as well. */
2089 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
2090 copy = emit_call_insn (pattern);
2091 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2093 /* Because the USAGE information potentially contains objects other
2094 than hard registers, we need to copy it. */
2095 CALL_INSN_FUNCTION_USAGE (copy)
2096 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn), map);
2100 try_constants (cc0_insn, map);
2103 try_constants (copy, map);
2105 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2106 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2107 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2111 /* If this is the loop start label, then we don't need to emit a
2112 copy of this label since no one will use it. */
2114 if (insn != start_label)
2116 copy = emit_label (get_label_from_map (map,
2117 CODE_LABEL_NUMBER (insn)));
2123 copy = emit_barrier ();
2127 /* VTOP notes are valid only before the loop exit test. If placed
2128 anywhere else, loop may generate bad code. */
2130 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2131 && (NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2132 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2133 copy = emit_note (NOTE_SOURCE_FILE (insn),
2134 NOTE_LINE_NUMBER (insn));
2144 map->insn_map[INSN_UID (insn)] = copy;
2146 while (insn != copy_end);
2148 /* Now finish coping the REG_NOTES. */
2152 insn = NEXT_INSN (insn);
2153 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2154 || GET_CODE (insn) == CALL_INSN)
2155 && map->insn_map[INSN_UID (insn)])
2156 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2158 while (insn != copy_end);
2160 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2161 each of these notes here, since there may be some important ones, such as
2162 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2163 iteration, because the original notes won't be deleted.
2165 We can't use insert_before here, because when from preconditioning,
2166 insert_before points before the loop. We can't use copy_end, because
2167 there may be insns already inserted after it (which we don't want to
2168 copy) when not from preconditioning code. */
2170 if (! last_iteration)
2172 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2174 if (GET_CODE (insn) == NOTE
2175 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED)
2176 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2180 if (final_label && LABEL_NUSES (final_label) > 0)
2181 emit_label (final_label);
2183 tem = gen_sequence ();
2185 emit_insn_before (tem, insert_before);
2188 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2189 emitted. This will correctly handle the case where the increment value
2190 won't fit in the immediate field of a PLUS insns. */
2193 emit_unrolled_add (dest_reg, src_reg, increment)
2194 rtx dest_reg, src_reg, increment;
2198 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2199 dest_reg, 0, OPTAB_LIB_WIDEN);
2201 if (dest_reg != result)
2202 emit_move_insn (dest_reg, result);
2205 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2206 is a backward branch in that range that branches to somewhere between
2207 LOOP_START and INSN. Returns 0 otherwise. */
2209 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2210 In practice, this is not a problem, because this function is seldom called,
2211 and uses a negligible amount of CPU time on average. */
2214 back_branch_in_range_p (insn, loop_start, loop_end)
2216 rtx loop_start, loop_end;
2218 rtx p, q, target_insn;
2219 rtx orig_loop_end = loop_end;
2221 /* Stop before we get to the backward branch at the end of the loop. */
2222 loop_end = prev_nonnote_insn (loop_end);
2223 if (GET_CODE (loop_end) == BARRIER)
2224 loop_end = PREV_INSN (loop_end);
2226 /* Check in case insn has been deleted, search forward for first non
2227 deleted insn following it. */
2228 while (INSN_DELETED_P (insn))
2229 insn = NEXT_INSN (insn);
2231 /* Check for the case where insn is the last insn in the loop. Deal
2232 with the case where INSN was a deleted loop test insn, in which case
2233 it will now be the NOTE_LOOP_END. */
2234 if (insn == loop_end || insn == orig_loop_end)
2237 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2239 if (GET_CODE (p) == JUMP_INSN)
2241 target_insn = JUMP_LABEL (p);
2243 /* Search from loop_start to insn, to see if one of them is
2244 the target_insn. We can't use INSN_LUID comparisons here,
2245 since insn may not have an LUID entry. */
2246 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2247 if (q == target_insn)
2255 /* Try to generate the simplest rtx for the expression
2256 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2260 fold_rtx_mult_add (mult1, mult2, add1, mode)
2261 rtx mult1, mult2, add1;
2262 enum machine_mode mode;
2267 /* The modes must all be the same. This should always be true. For now,
2268 check to make sure. */
2269 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2270 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2271 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2274 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2275 will be a constant. */
2276 if (GET_CODE (mult1) == CONST_INT)
2283 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2285 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2287 /* Again, put the constant second. */
2288 if (GET_CODE (add1) == CONST_INT)
2295 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2297 result = gen_rtx_PLUS (mode, add1, mult_res);
2302 /* Searches the list of induction struct's for the biv BL, to try to calculate
2303 the total increment value for one iteration of the loop as a constant.
2305 Returns the increment value as an rtx, simplified as much as possible,
2306 if it can be calculated. Otherwise, returns 0. */
2309 biv_total_increment (bl, loop_start, loop_end)
2310 struct iv_class *bl;
2311 rtx loop_start, loop_end;
2313 struct induction *v;
2316 /* For increment, must check every instruction that sets it. Each
2317 instruction must be executed only once each time through the loop.
2318 To verify this, we check that the insn is always executed, and that
2319 there are no backward branches after the insn that branch to before it.
2320 Also, the insn must have a mult_val of one (to make sure it really is
2323 result = const0_rtx;
2324 for (v = bl->biv; v; v = v->next_iv)
2326 if (v->always_computable && v->mult_val == const1_rtx
2327 && ! v->maybe_multiple)
2328 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2336 /* Determine the initial value of the iteration variable, and the amount
2337 that it is incremented each loop. Use the tables constructed by
2338 the strength reduction pass to calculate these values.
2340 Initial_value and/or increment are set to zero if their values could not
2344 iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
2345 rtx iteration_var, *initial_value, *increment;
2346 rtx loop_start, loop_end;
2348 struct iv_class *bl;
2350 struct induction *v;
2353 /* Clear the result values, in case no answer can be found. */
2357 /* The iteration variable can be either a giv or a biv. Check to see
2358 which it is, and compute the variable's initial value, and increment
2359 value if possible. */
2361 /* If this is a new register, can't handle it since we don't have any
2362 reg_iv_type entry for it. */
2363 if ((unsigned) REGNO (iteration_var) > reg_iv_type->num_elements)
2365 if (loop_dump_stream)
2366 fprintf (loop_dump_stream,
2367 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2371 /* Reject iteration variables larger than the host wide int size, since they
2372 could result in a number of iterations greater than the range of our
2373 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2374 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2375 > HOST_BITS_PER_WIDE_INT))
2377 if (loop_dump_stream)
2378 fprintf (loop_dump_stream,
2379 "Loop unrolling: Iteration var rejected because mode too large.\n");
2382 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2384 if (loop_dump_stream)
2385 fprintf (loop_dump_stream,
2386 "Loop unrolling: Iteration var not an integer.\n");
2389 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2391 /* Grab initial value, only useful if it is a constant. */
2392 bl = reg_biv_class[REGNO (iteration_var)];
2393 *initial_value = bl->initial_value;
2395 *increment = biv_total_increment (bl, loop_start, loop_end);
2397 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2400 /* ??? The code below does not work because the incorrect number of
2401 iterations is calculated when the biv is incremented after the giv
2402 is set (which is the usual case). This can probably be accounted
2403 for by biasing the initial_value by subtracting the amount of the
2404 increment that occurs between the giv set and the giv test. However,
2405 a giv as an iterator is very rare, so it does not seem worthwhile
2407 /* ??? An example failure is: i = 6; do {;} while (i++ < 9). */
2408 if (loop_dump_stream)
2409 fprintf (loop_dump_stream,
2410 "Loop unrolling: Giv iterators are not handled.\n");
2413 /* Initial value is mult_val times the biv's initial value plus
2414 add_val. Only useful if it is a constant. */
2415 v = REG_IV_INFO (REGNO (iteration_var));
2416 bl = reg_biv_class[REGNO (v->src_reg)];
2417 *initial_value = fold_rtx_mult_add (v->mult_val, bl->initial_value,
2418 v->add_val, v->mode);
2420 /* Increment value is mult_val times the increment value of the biv. */
2422 *increment = biv_total_increment (bl, loop_start, loop_end);
2424 *increment = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx,
2430 if (loop_dump_stream)
2431 fprintf (loop_dump_stream,
2432 "Loop unrolling: Not basic or general induction var.\n");
2438 /* For each biv and giv, determine whether it can be safely split into
2439 a different variable for each unrolled copy of the loop body. If it
2440 is safe to split, then indicate that by saving some useful info
2441 in the splittable_regs array.
2443 If the loop is being completely unrolled, then splittable_regs will hold
2444 the current value of the induction variable while the loop is unrolled.
2445 It must be set to the initial value of the induction variable here.
2446 Otherwise, splittable_regs will hold the difference between the current
2447 value of the induction variable and the value the induction variable had
2448 at the top of the loop. It must be set to the value 0 here.
2450 Returns the total number of instructions that set registers that are
2453 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2454 constant values are unnecessary, since we can easily calculate increment
2455 values in this case even if nothing is constant. The increment value
2456 should not involve a multiply however. */
2458 /* ?? Even if the biv/giv increment values aren't constant, it may still
2459 be beneficial to split the variable if the loop is only unrolled a few
2460 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2463 find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
2464 unroll_number, n_iterations)
2465 enum unroll_types unroll_type;
2466 rtx loop_start, loop_end;
2467 rtx end_insert_before;
2469 unsigned HOST_WIDE_INT n_iterations;
2471 struct iv_class *bl;
2472 struct induction *v;
2474 rtx biv_final_value;
2478 for (bl = loop_iv_list; bl; bl = bl->next)
2480 /* Biv_total_increment must return a constant value,
2481 otherwise we can not calculate the split values. */
2483 increment = biv_total_increment (bl, loop_start, loop_end);
2484 if (! increment || GET_CODE (increment) != CONST_INT)
2487 /* The loop must be unrolled completely, or else have a known number
2488 of iterations and only one exit, or else the biv must be dead
2489 outside the loop, or else the final value must be known. Otherwise,
2490 it is unsafe to split the biv since it may not have the proper
2491 value on loop exit. */
2493 /* loop_number_exit_count is non-zero if the loop has an exit other than
2494 a fall through at the end. */
2497 biv_final_value = 0;
2498 if (unroll_type != UNROLL_COMPLETELY
2499 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2500 || unroll_type == UNROLL_NAIVE)
2501 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2503 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2504 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2505 < INSN_LUID (bl->init_insn))
2506 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2507 && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end,
2511 /* If any of the insns setting the BIV don't do so with a simple
2512 PLUS, we don't know how to split it. */
2513 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2514 if ((tem = single_set (v->insn)) == 0
2515 || GET_CODE (SET_DEST (tem)) != REG
2516 || REGNO (SET_DEST (tem)) != bl->regno
2517 || GET_CODE (SET_SRC (tem)) != PLUS)
2520 /* If final value is non-zero, then must emit an instruction which sets
2521 the value of the biv to the proper value. This is done after
2522 handling all of the givs, since some of them may need to use the
2523 biv's value in their initialization code. */
2525 /* This biv is splittable. If completely unrolling the loop, save
2526 the biv's initial value. Otherwise, save the constant zero. */
2528 if (biv_splittable == 1)
2530 if (unroll_type == UNROLL_COMPLETELY)
2532 /* If the initial value of the biv is itself (i.e. it is too
2533 complicated for strength_reduce to compute), or is a hard
2534 register, or it isn't invariant, then we must create a new
2535 pseudo reg to hold the initial value of the biv. */
2537 if (GET_CODE (bl->initial_value) == REG
2538 && (REGNO (bl->initial_value) == bl->regno
2539 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2540 || ! invariant_p (bl->initial_value)))
2542 rtx tem = gen_reg_rtx (bl->biv->mode);
2544 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2545 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2548 if (loop_dump_stream)
2549 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2550 bl->regno, REGNO (tem));
2552 splittable_regs[bl->regno] = tem;
2555 splittable_regs[bl->regno] = bl->initial_value;
2558 splittable_regs[bl->regno] = const0_rtx;
2560 /* Save the number of instructions that modify the biv, so that
2561 we can treat the last one specially. */
2563 splittable_regs_updates[bl->regno] = bl->biv_count;
2564 result += bl->biv_count;
2566 if (loop_dump_stream)
2567 fprintf (loop_dump_stream,
2568 "Biv %d safe to split.\n", bl->regno);
2571 /* Check every giv that depends on this biv to see whether it is
2572 splittable also. Even if the biv isn't splittable, givs which
2573 depend on it may be splittable if the biv is live outside the
2574 loop, and the givs aren't. */
2576 result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
2577 increment, unroll_number);
2579 /* If final value is non-zero, then must emit an instruction which sets
2580 the value of the biv to the proper value. This is done after
2581 handling all of the givs, since some of them may need to use the
2582 biv's value in their initialization code. */
2583 if (biv_final_value)
2585 /* If the loop has multiple exits, emit the insns before the
2586 loop to ensure that it will always be executed no matter
2587 how the loop exits. Otherwise emit the insn after the loop,
2588 since this is slightly more efficient. */
2589 if (! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
2590 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2595 /* Create a new register to hold the value of the biv, and then
2596 set the biv to its final value before the loop start. The biv
2597 is set to its final value before loop start to ensure that
2598 this insn will always be executed, no matter how the loop
2600 rtx tem = gen_reg_rtx (bl->biv->mode);
2601 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2603 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2605 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2609 if (loop_dump_stream)
2610 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2611 REGNO (bl->biv->src_reg), REGNO (tem));
2613 /* Set up the mapping from the original biv register to the new
2615 bl->biv->src_reg = tem;
2622 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2623 for the instruction that is using it. Do not make any changes to that
2627 verify_addresses (v, giv_inc, unroll_number)
2628 struct induction *v;
2633 rtx orig_addr = *v->location;
2634 rtx last_addr = plus_constant (v->dest_reg,
2635 INTVAL (giv_inc) * (unroll_number - 1));
2637 /* First check to see if either address would fail. Handle the fact
2638 that we have may have a match_dup. */
2639 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2640 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2643 /* Now put things back the way they were before. This should always
2645 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2651 /* For every giv based on the biv BL, check to determine whether it is
2652 splittable. This is a subroutine to find_splittable_regs ().
2654 Return the number of instructions that set splittable registers. */
2657 find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
2659 struct iv_class *bl;
2660 enum unroll_types unroll_type;
2661 rtx loop_start, loop_end;
2665 struct induction *v, *v2;
2670 /* Scan the list of givs, and set the same_insn field when there are
2671 multiple identical givs in the same insn. */
2672 for (v = bl->giv; v; v = v->next_iv)
2673 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2674 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2678 for (v = bl->giv; v; v = v->next_iv)
2682 /* Only split the giv if it has already been reduced, or if the loop is
2683 being completely unrolled. */
2684 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2687 /* The giv can be split if the insn that sets the giv is executed once
2688 and only once on every iteration of the loop. */
2689 /* An address giv can always be split. v->insn is just a use not a set,
2690 and hence it does not matter whether it is always executed. All that
2691 matters is that all the biv increments are always executed, and we
2692 won't reach here if they aren't. */
2693 if (v->giv_type != DEST_ADDR
2694 && (! v->always_computable
2695 || back_branch_in_range_p (v->insn, loop_start, loop_end)))
2698 /* The giv increment value must be a constant. */
2699 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2701 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2704 /* The loop must be unrolled completely, or else have a known number of
2705 iterations and only one exit, or else the giv must be dead outside
2706 the loop, or else the final value of the giv must be known.
2707 Otherwise, it is not safe to split the giv since it may not have the
2708 proper value on loop exit. */
2710 /* The used outside loop test will fail for DEST_ADDR givs. They are
2711 never used outside the loop anyways, so it is always safe to split a
2715 if (unroll_type != UNROLL_COMPLETELY
2716 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2717 || unroll_type == UNROLL_NAIVE)
2718 && v->giv_type != DEST_ADDR
2719 /* The next part is true if the pseudo is used outside the loop.
2720 We assume that this is true for any pseudo created after loop
2721 starts, because we don't have a reg_n_info entry for them. */
2722 && (REGNO (v->dest_reg) >= max_reg_before_loop
2723 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2724 /* Check for the case where the pseudo is set by a shift/add
2725 sequence, in which case the first insn setting the pseudo
2726 is the first insn of the shift/add sequence. */
2727 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2728 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2729 != INSN_UID (XEXP (tem, 0)))))
2730 /* Line above always fails if INSN was moved by loop opt. */
2731 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2732 >= INSN_LUID (loop_end)))
2733 /* Givs made from biv increments are missed by the above test, so
2734 test explicitly for them. */
2735 && (REGNO (v->dest_reg) < first_increment_giv
2736 || REGNO (v->dest_reg) > last_increment_giv)
2737 && ! (final_value = v->final_value))
2741 /* Currently, non-reduced/final-value givs are never split. */
2742 /* Should emit insns after the loop if possible, as the biv final value
2745 /* If the final value is non-zero, and the giv has not been reduced,
2746 then must emit an instruction to set the final value. */
2747 if (final_value && !v->new_reg)
2749 /* Create a new register to hold the value of the giv, and then set
2750 the giv to its final value before the loop start. The giv is set
2751 to its final value before loop start to ensure that this insn
2752 will always be executed, no matter how we exit. */
2753 tem = gen_reg_rtx (v->mode);
2754 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2755 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2758 if (loop_dump_stream)
2759 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2760 REGNO (v->dest_reg), REGNO (tem));
2766 /* This giv is splittable. If completely unrolling the loop, save the
2767 giv's initial value. Otherwise, save the constant zero for it. */
2769 if (unroll_type == UNROLL_COMPLETELY)
2771 /* It is not safe to use bl->initial_value here, because it may not
2772 be invariant. It is safe to use the initial value stored in
2773 the splittable_regs array if it is set. In rare cases, it won't
2774 be set, so then we do exactly the same thing as
2775 find_splittable_regs does to get a safe value. */
2776 rtx biv_initial_value;
2778 if (splittable_regs[bl->regno])
2779 biv_initial_value = splittable_regs[bl->regno];
2780 else if (GET_CODE (bl->initial_value) != REG
2781 || (REGNO (bl->initial_value) != bl->regno
2782 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2783 biv_initial_value = bl->initial_value;
2786 rtx tem = gen_reg_rtx (bl->biv->mode);
2788 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2789 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2791 biv_initial_value = tem;
2793 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2794 v->add_val, v->mode);
2801 /* If a giv was combined with another giv, then we can only split
2802 this giv if the giv it was combined with was reduced. This
2803 is because the value of v->new_reg is meaningless in this
2805 if (v->same && ! v->same->new_reg)
2807 if (loop_dump_stream)
2808 fprintf (loop_dump_stream,
2809 "giv combined with unreduced giv not split.\n");
2812 /* If the giv is an address destination, it could be something other
2813 than a simple register, these have to be treated differently. */
2814 else if (v->giv_type == DEST_REG)
2816 /* If value is not a constant, register, or register plus
2817 constant, then compute its value into a register before
2818 loop start. This prevents invalid rtx sharing, and should
2819 generate better code. We can use bl->initial_value here
2820 instead of splittable_regs[bl->regno] because this code
2821 is going before the loop start. */
2822 if (unroll_type == UNROLL_COMPLETELY
2823 && GET_CODE (value) != CONST_INT
2824 && GET_CODE (value) != REG
2825 && (GET_CODE (value) != PLUS
2826 || GET_CODE (XEXP (value, 0)) != REG
2827 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2829 rtx tem = gen_reg_rtx (v->mode);
2830 record_base_value (REGNO (tem), v->add_val, 0);
2831 emit_iv_add_mult (bl->initial_value, v->mult_val,
2832 v->add_val, tem, loop_start);
2836 splittable_regs[REGNO (v->new_reg)] = value;
2837 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2841 /* Splitting address givs is useful since it will often allow us
2842 to eliminate some increment insns for the base giv as
2845 /* If the addr giv is combined with a dest_reg giv, then all
2846 references to that dest reg will be remapped, which is NOT
2847 what we want for split addr regs. We always create a new
2848 register for the split addr giv, just to be safe. */
2850 /* If we have multiple identical address givs within a
2851 single instruction, then use a single pseudo reg for
2852 both. This is necessary in case one is a match_dup
2855 v->const_adjust = 0;
2859 v->dest_reg = v->same_insn->dest_reg;
2860 if (loop_dump_stream)
2861 fprintf (loop_dump_stream,
2862 "Sharing address givs in insn %d\n",
2863 INSN_UID (v->insn));
2865 /* If multiple address GIVs have been combined with the
2866 same dest_reg GIV, do not create a new register for
2868 else if (unroll_type != UNROLL_COMPLETELY
2869 && v->giv_type == DEST_ADDR
2870 && v->same && v->same->giv_type == DEST_ADDR
2871 && v->same->unrolled
2872 /* combine_givs_p may return true for some cases
2873 where the add and mult values are not equal.
2874 To share a register here, the values must be
2876 && rtx_equal_p (v->same->mult_val, v->mult_val)
2877 && rtx_equal_p (v->same->add_val, v->add_val)
2878 /* If the memory references have different modes,
2879 then the address may not be valid and we must
2880 not share registers. */
2881 && verify_addresses (v, giv_inc, unroll_number))
2883 v->dest_reg = v->same->dest_reg;
2886 else if (unroll_type != UNROLL_COMPLETELY)
2888 /* If not completely unrolling the loop, then create a new
2889 register to hold the split value of the DEST_ADDR giv.
2890 Emit insn to initialize its value before loop start. */
2892 rtx tem = gen_reg_rtx (v->mode);
2893 struct induction *same = v->same;
2894 rtx new_reg = v->new_reg;
2895 record_base_value (REGNO (tem), v->add_val, 0);
2897 if (same && same->derived_from)
2899 /* calculate_giv_inc doesn't work for derived givs.
2900 copy_loop_body works around the problem for the
2901 DEST_REG givs themselves, but it can't handle
2902 DEST_ADDR givs that have been combined with
2903 derived a derived DEST_REG giv.
2904 So Handle V as if the giv from which V->SAME has
2905 been derived has been combined with V.
2906 recombine_givs only derives givs from givs that
2907 are reduced the ordinary, so we need not worry
2908 about same->derived_from being in turn derived. */
2910 same = same->derived_from;
2911 new_reg = express_from (same, v);
2914 /* If the address giv has a constant in its new_reg value,
2915 then this constant can be pulled out and put in value,
2916 instead of being part of the initialization code. */
2918 if (GET_CODE (new_reg) == PLUS
2919 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
2922 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
2924 /* Only succeed if this will give valid addresses.
2925 Try to validate both the first and the last
2926 address resulting from loop unrolling, if
2927 one fails, then can't do const elim here. */
2928 if (verify_addresses (v, giv_inc, unroll_number))
2930 /* Save the negative of the eliminated const, so
2931 that we can calculate the dest_reg's increment
2933 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
2935 new_reg = XEXP (new_reg, 0);
2936 if (loop_dump_stream)
2937 fprintf (loop_dump_stream,
2938 "Eliminating constant from giv %d\n",
2947 /* If the address hasn't been checked for validity yet, do so
2948 now, and fail completely if either the first or the last
2949 unrolled copy of the address is not a valid address
2950 for the instruction that uses it. */
2951 if (v->dest_reg == tem
2952 && ! verify_addresses (v, giv_inc, unroll_number))
2954 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2955 if (v2->same_insn == v)
2958 if (loop_dump_stream)
2959 fprintf (loop_dump_stream,
2960 "Invalid address for giv at insn %d\n",
2961 INSN_UID (v->insn));
2965 v->new_reg = new_reg;
2968 /* We set this after the address check, to guarantee that
2969 the register will be initialized. */
2972 /* To initialize the new register, just move the value of
2973 new_reg into it. This is not guaranteed to give a valid
2974 instruction on machines with complex addressing modes.
2975 If we can't recognize it, then delete it and emit insns
2976 to calculate the value from scratch. */
2977 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
2978 copy_rtx (v->new_reg)),
2980 if (recog_memoized (PREV_INSN (loop_start)) < 0)
2984 /* We can't use bl->initial_value to compute the initial
2985 value, because the loop may have been preconditioned.
2986 We must calculate it from NEW_REG. Try using
2987 force_operand instead of emit_iv_add_mult. */
2988 delete_insn (PREV_INSN (loop_start));
2991 ret = force_operand (v->new_reg, tem);
2993 emit_move_insn (tem, ret);
2994 sequence = gen_sequence ();
2996 emit_insn_before (sequence, loop_start);
2998 if (loop_dump_stream)
2999 fprintf (loop_dump_stream,
3000 "Invalid init insn, rewritten.\n");
3005 v->dest_reg = value;
3007 /* Check the resulting address for validity, and fail
3008 if the resulting address would be invalid. */
3009 if (! verify_addresses (v, giv_inc, unroll_number))
3011 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3012 if (v2->same_insn == v)
3015 if (loop_dump_stream)
3016 fprintf (loop_dump_stream,
3017 "Invalid address for giv at insn %d\n",
3018 INSN_UID (v->insn));
3021 if (v->same && v->same->derived_from)
3023 /* Handle V as if the giv from which V->SAME has
3024 been derived has been combined with V. */
3026 v->same = v->same->derived_from;
3027 v->new_reg = express_from (v->same, v);
3032 /* Store the value of dest_reg into the insn. This sharing
3033 will not be a problem as this insn will always be copied
3036 *v->location = v->dest_reg;
3038 /* If this address giv is combined with a dest reg giv, then
3039 save the base giv's induction pointer so that we will be
3040 able to handle this address giv properly. The base giv
3041 itself does not have to be splittable. */
3043 if (v->same && v->same->giv_type == DEST_REG)
3044 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3046 if (GET_CODE (v->new_reg) == REG)
3048 /* This giv maybe hasn't been combined with any others.
3049 Make sure that it's giv is marked as splittable here. */
3051 splittable_regs[REGNO (v->new_reg)] = value;
3052 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3054 /* Make it appear to depend upon itself, so that the
3055 giv will be properly split in the main loop above. */
3059 addr_combined_regs[REGNO (v->new_reg)] = v;
3063 if (loop_dump_stream)
3064 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3070 /* Currently, unreduced giv's can't be split. This is not too much
3071 of a problem since unreduced giv's are not live across loop
3072 iterations anyways. When unrolling a loop completely though,
3073 it makes sense to reduce&split givs when possible, as this will
3074 result in simpler instructions, and will not require that a reg
3075 be live across loop iterations. */
3077 splittable_regs[REGNO (v->dest_reg)] = value;
3078 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3079 REGNO (v->dest_reg), INSN_UID (v->insn));
3085 /* Unreduced givs are only updated once by definition. Reduced givs
3086 are updated as many times as their biv is. Mark it so if this is
3087 a splittable register. Don't need to do anything for address givs
3088 where this may not be a register. */
3090 if (GET_CODE (v->new_reg) == REG)
3094 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3096 if (count > 1 && v->derived_from)
3097 /* In this case, there is one set where the giv insn was and one
3098 set each after each biv increment. (Most are likely dead.) */
3101 splittable_regs_updates[REGNO (v->new_reg)] = count;
3106 if (loop_dump_stream)
3110 if (GET_CODE (v->dest_reg) == CONST_INT)
3112 else if (GET_CODE (v->dest_reg) != REG)
3113 regnum = REGNO (XEXP (v->dest_reg, 0));
3115 regnum = REGNO (v->dest_reg);
3116 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3117 regnum, INSN_UID (v->insn));
3124 /* Try to prove that the register is dead after the loop exits. Trace every
3125 loop exit looking for an insn that will always be executed, which sets
3126 the register to some value, and appears before the first use of the register
3127 is found. If successful, then return 1, otherwise return 0. */
3129 /* ?? Could be made more intelligent in the handling of jumps, so that
3130 it can search past if statements and other similar structures. */
3133 reg_dead_after_loop (reg, loop_start, loop_end)
3134 rtx reg, loop_start, loop_end;
3139 int label_count = 0;
3140 int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
3142 /* In addition to checking all exits of this loop, we must also check
3143 all exits of inner nested loops that would exit this loop. We don't
3144 have any way to identify those, so we just give up if there are any
3145 such inner loop exits. */
3147 for (label = loop_number_exit_labels[this_loop_num]; label;
3148 label = LABEL_NEXTREF (label))
3151 if (label_count != loop_number_exit_count[this_loop_num])
3154 /* HACK: Must also search the loop fall through exit, create a label_ref
3155 here which points to the loop_end, and append the loop_number_exit_labels
3157 label = gen_rtx_LABEL_REF (VOIDmode, loop_end);
3158 LABEL_NEXTREF (label) = loop_number_exit_labels[this_loop_num];
3160 for ( ; label; label = LABEL_NEXTREF (label))
3162 /* Succeed if find an insn which sets the biv or if reach end of
3163 function. Fail if find an insn that uses the biv, or if come to
3164 a conditional jump. */
3166 insn = NEXT_INSN (XEXP (label, 0));
3169 code = GET_CODE (insn);
3170 if (GET_RTX_CLASS (code) == 'i')
3174 if (reg_referenced_p (reg, PATTERN (insn)))
3177 set = single_set (insn);
3178 if (set && rtx_equal_p (SET_DEST (set), reg))
3182 if (code == JUMP_INSN)
3184 if (GET_CODE (PATTERN (insn)) == RETURN)
3186 else if (! simplejump_p (insn)
3187 /* Prevent infinite loop following infinite loops. */
3188 || jump_count++ > 20)
3191 insn = JUMP_LABEL (insn);
3194 insn = NEXT_INSN (insn);
3198 /* Success, the register is dead on all loop exits. */
3202 /* Try to calculate the final value of the biv, the value it will have at
3203 the end of the loop. If we can do it, return that value. */
3206 final_biv_value (bl, loop_start, loop_end, n_iterations)
3207 struct iv_class *bl;
3208 rtx loop_start, loop_end;
3209 unsigned HOST_WIDE_INT n_iterations;
3213 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3215 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3218 /* The final value for reversed bivs must be calculated differently than
3219 for ordinary bivs. In this case, there is already an insn after the
3220 loop which sets this biv's final value (if necessary), and there are
3221 no other loop exits, so we can return any value. */
3224 if (loop_dump_stream)
3225 fprintf (loop_dump_stream,
3226 "Final biv value for %d, reversed biv.\n", bl->regno);
3231 /* Try to calculate the final value as initial value + (number of iterations
3232 * increment). For this to work, increment must be invariant, the only
3233 exit from the loop must be the fall through at the bottom (otherwise
3234 it may not have its final value when the loop exits), and the initial
3235 value of the biv must be invariant. */
3237 if (n_iterations != 0
3238 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
3239 && invariant_p (bl->initial_value))
3241 increment = biv_total_increment (bl, loop_start, loop_end);
3243 if (increment && invariant_p (increment))
3245 /* Can calculate the loop exit value, emit insns after loop
3246 end to calculate this value into a temporary register in
3247 case it is needed later. */
3249 tem = gen_reg_rtx (bl->biv->mode);
3250 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3251 /* Make sure loop_end is not the last insn. */
3252 if (NEXT_INSN (loop_end) == 0)
3253 emit_note_after (NOTE_INSN_DELETED, loop_end);
3254 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3255 bl->initial_value, tem, NEXT_INSN (loop_end));
3257 if (loop_dump_stream)
3258 fprintf (loop_dump_stream,
3259 "Final biv value for %d, calculated.\n", bl->regno);
3265 /* Check to see if the biv is dead at all loop exits. */
3266 if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
3268 if (loop_dump_stream)
3269 fprintf (loop_dump_stream,
3270 "Final biv value for %d, biv dead after loop exit.\n",
3279 /* Try to calculate the final value of the giv, the value it will have at
3280 the end of the loop. If we can do it, return that value. */
3283 final_giv_value (v, loop_start, loop_end, n_iterations)
3284 struct induction *v;
3285 rtx loop_start, loop_end;
3286 unsigned HOST_WIDE_INT n_iterations;
3288 struct iv_class *bl;
3291 rtx insert_before, seq;
3293 bl = reg_biv_class[REGNO (v->src_reg)];
3295 /* The final value for givs which depend on reversed bivs must be calculated
3296 differently than for ordinary givs. In this case, there is already an
3297 insn after the loop which sets this giv's final value (if necessary),
3298 and there are no other loop exits, so we can return any value. */
3301 if (loop_dump_stream)
3302 fprintf (loop_dump_stream,
3303 "Final giv value for %d, depends on reversed biv\n",
3304 REGNO (v->dest_reg));
3308 /* Try to calculate the final value as a function of the biv it depends
3309 upon. The only exit from the loop must be the fall through at the bottom
3310 (otherwise it may not have its final value when the loop exits). */
3312 /* ??? Can calculate the final giv value by subtracting off the
3313 extra biv increments times the giv's mult_val. The loop must have
3314 only one exit for this to work, but the loop iterations does not need
3317 if (n_iterations != 0
3318 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
3320 /* ?? It is tempting to use the biv's value here since these insns will
3321 be put after the loop, and hence the biv will have its final value
3322 then. However, this fails if the biv is subsequently eliminated.
3323 Perhaps determine whether biv's are eliminable before trying to
3324 determine whether giv's are replaceable so that we can use the
3325 biv value here if it is not eliminable. */
3327 /* We are emitting code after the end of the loop, so we must make
3328 sure that bl->initial_value is still valid then. It will still
3329 be valid if it is invariant. */
3331 increment = biv_total_increment (bl, loop_start, loop_end);
3333 if (increment && invariant_p (increment)
3334 && invariant_p (bl->initial_value))
3336 /* Can calculate the loop exit value of its biv as
3337 (n_iterations * increment) + initial_value */
3339 /* The loop exit value of the giv is then
3340 (final_biv_value - extra increments) * mult_val + add_val.
3341 The extra increments are any increments to the biv which
3342 occur in the loop after the giv's value is calculated.
3343 We must search from the insn that sets the giv to the end
3344 of the loop to calculate this value. */
3346 insert_before = NEXT_INSN (loop_end);
3348 /* Put the final biv value in tem. */
3349 tem = gen_reg_rtx (bl->biv->mode);
3350 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3351 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3352 bl->initial_value, tem, insert_before);
3354 /* Subtract off extra increments as we find them. */
3355 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3356 insn = NEXT_INSN (insn))
3358 struct induction *biv;
3360 for (biv = bl->biv; biv; biv = biv->next_iv)
3361 if (biv->insn == insn)
3364 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3365 biv->add_val, NULL_RTX, 0,
3367 seq = gen_sequence ();
3369 emit_insn_before (seq, insert_before);
3373 /* Now calculate the giv's final value. */
3374 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3377 if (loop_dump_stream)
3378 fprintf (loop_dump_stream,
3379 "Final giv value for %d, calc from biv's value.\n",
3380 REGNO (v->dest_reg));
3386 /* Replaceable giv's should never reach here. */
3390 /* Check to see if the biv is dead at all loop exits. */
3391 if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
3393 if (loop_dump_stream)
3394 fprintf (loop_dump_stream,
3395 "Final giv value for %d, giv dead after loop exit.\n",
3396 REGNO (v->dest_reg));
3405 /* Look back before LOOP_START for then insn that sets REG and return
3406 the equivalent constant if there is a REG_EQUAL note otherwise just
3407 the SET_SRC of REG. */
3410 loop_find_equiv_value (loop_start, reg)
3418 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3420 if (GET_CODE (insn) == CODE_LABEL)
3423 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3424 && reg_set_p (reg, insn))
3426 /* We found the last insn before the loop that sets the register.
3427 If it sets the entire register, and has a REG_EQUAL note,
3428 then use the value of the REG_EQUAL note. */
3429 if ((set = single_set (insn))
3430 && (SET_DEST (set) == reg))
3432 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3434 /* Only use the REG_EQUAL note if it is a constant.
3435 Other things, divide in particular, will cause
3436 problems later if we use them. */
3437 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3438 && CONSTANT_P (XEXP (note, 0)))
3439 ret = XEXP (note, 0);
3441 ret = SET_SRC (set);
3450 /* Return a simplified rtx for the expression OP - REG.
3452 REG must appear in OP, and OP must be a register or the sum of a register
3455 Thus, the return value must be const0_rtx or the second term.
3457 The caller is responsible for verifying that REG appears in OP and OP has
3461 subtract_reg_term (op, reg)
3466 if (GET_CODE (op) == PLUS)
3468 if (XEXP (op, 0) == reg)
3469 return XEXP (op, 1);
3470 else if (XEXP (op, 1) == reg)
3471 return XEXP (op, 0);
3473 /* OP does not contain REG as a term. */
3478 /* Find and return register term common to both expressions OP0 and
3479 OP1 or NULL_RTX if no such term exists. Each expression must be a
3480 REG or a PLUS of a REG. */
3483 find_common_reg_term (op0, op1)
3486 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3487 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3494 if (GET_CODE (op0) == PLUS)
3495 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3497 op01 = const0_rtx, op00 = op0;
3499 if (GET_CODE (op1) == PLUS)
3500 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3502 op11 = const0_rtx, op10 = op1;
3504 /* Find and return common register term if present. */
3505 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3507 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3511 /* No common register term found. */
3516 /* Calculate the number of loop iterations. Returns the exact number of loop
3517 iterations if it can be calculated, otherwise returns zero. */
3519 unsigned HOST_WIDE_INT
3520 loop_iterations (loop_start, loop_end, loop_info)
3521 rtx loop_start, loop_end;
3522 struct loop_info *loop_info;
3524 rtx comparison, comparison_value;
3525 rtx iteration_var, initial_value, increment, final_value;
3526 enum rtx_code comparison_code;
3527 HOST_WIDE_INT abs_inc;
3528 unsigned HOST_WIDE_INT abs_diff;
3531 int unsigned_p, compare_dir, final_larger;
3536 loop_info->n_iterations = 0;
3537 loop_info->initial_value = 0;
3538 loop_info->initial_equiv_value = 0;
3539 loop_info->comparison_value = 0;
3540 loop_info->final_value = 0;
3541 loop_info->final_equiv_value = 0;
3542 loop_info->increment = 0;
3543 loop_info->iteration_var = 0;
3544 loop_info->unroll_number = 1;
3545 loop_info->vtop = 0;
3547 /* We used to use prev_nonnote_insn here, but that fails because it might
3548 accidentally get the branch for a contained loop if the branch for this
3549 loop was deleted. We can only trust branches immediately before the
3551 last_loop_insn = PREV_INSN (loop_end);
3553 /* ??? We should probably try harder to find the jump insn
3554 at the end of the loop. The following code assumes that
3555 the last loop insn is a jump to the top of the loop. */
3556 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3558 if (loop_dump_stream)
3559 fprintf (loop_dump_stream,
3560 "Loop iterations: No final conditional branch found.\n");
3564 /* If there is a more than a single jump to the top of the loop
3565 we cannot (easily) determine the iteration count. */
3566 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3568 if (loop_dump_stream)
3569 fprintf (loop_dump_stream,
3570 "Loop iterations: Loop has multiple back edges.\n");
3574 /* Find the iteration variable. If the last insn is a conditional
3575 branch, and the insn before tests a register value, make that the
3576 iteration variable. */
3578 comparison = get_condition_for_loop (last_loop_insn);
3579 if (comparison == 0)
3581 if (loop_dump_stream)
3582 fprintf (loop_dump_stream,
3583 "Loop iterations: No final comparison found.\n");
3587 /* ??? Get_condition may switch position of induction variable and
3588 invariant register when it canonicalizes the comparison. */
3590 comparison_code = GET_CODE (comparison);
3591 iteration_var = XEXP (comparison, 0);
3592 comparison_value = XEXP (comparison, 1);
3594 /* Check if there is a NOTE_INSN_LOOP_VTOP note. If there is,
3595 that means that this is a for or while style loop, with
3596 a loop exit test at the start. Thus, we can assume that
3597 the loop condition was true when the loop was entered.
3599 We start at the end and search backwards for the previous
3600 NOTE. If there is no NOTE_INSN_LOOP_VTOP for this loop,
3601 the search will stop at the NOTE_INSN_LOOP_CONT. */
3604 vtop = PREV_INSN (vtop);
3605 while (GET_CODE (vtop) != NOTE
3606 || NOTE_LINE_NUMBER (vtop) > 0
3607 || NOTE_LINE_NUMBER (vtop) == NOTE_REPEATED_LINE_NUMBER
3608 || NOTE_LINE_NUMBER (vtop) == NOTE_INSN_DELETED);
3609 if (NOTE_LINE_NUMBER (vtop) != NOTE_INSN_LOOP_VTOP)
3611 loop_info->vtop = vtop;
3613 if (GET_CODE (iteration_var) != REG)
3615 if (loop_dump_stream)
3616 fprintf (loop_dump_stream,
3617 "Loop iterations: Comparison not against register.\n");
3621 /* Loop iterations is always called before any new registers are created
3622 now, so this should never occur. */
3624 if (REGNO (iteration_var) >= max_reg_before_loop)
3627 iteration_info (iteration_var, &initial_value, &increment,
3628 loop_start, loop_end);
3629 if (initial_value == 0)
3630 /* iteration_info already printed a message. */
3635 switch (comparison_code)
3650 /* Cannot determine loop iterations with this case. */
3669 /* If the comparison value is an invariant register, then try to find
3670 its value from the insns before the start of the loop. */
3672 final_value = comparison_value;
3673 if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
3675 final_value = loop_find_equiv_value (loop_start, comparison_value);
3676 /* If we don't get an invariant final value, we are better
3677 off with the original register. */
3678 if (!invariant_p (final_value))
3679 final_value = comparison_value;
3682 /* Calculate the approximate final value of the induction variable
3683 (on the last successful iteration). The exact final value
3684 depends on the branch operator, and increment sign. It will be
3685 wrong if the iteration variable is not incremented by one each
3686 time through the loop and (comparison_value + off_by_one -
3687 initial_value) % increment != 0.
3688 ??? Note that the final_value may overflow and thus final_larger
3689 will be bogus. A potentially infinite loop will be classified
3690 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3692 final_value = plus_constant (final_value, off_by_one);
3694 /* Save the calculated values describing this loop's bounds, in case
3695 precondition_loop_p will need them later. These values can not be
3696 recalculated inside precondition_loop_p because strength reduction
3697 optimizations may obscure the loop's structure.
3699 These values are only required by precondition_loop_p and insert_bct
3700 whenever the number of iterations cannot be computed at compile time.
3701 Only the difference between final_value and initial_value is
3702 important. Note that final_value is only approximate. */
3703 loop_info->initial_value = initial_value;
3704 loop_info->comparison_value = comparison_value;
3705 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3706 loop_info->increment = increment;
3707 loop_info->iteration_var = iteration_var;
3708 loop_info->comparison_code = comparison_code;
3710 /* Try to determine the iteration count for loops such
3711 as (for i = init; i < init + const; i++). When running the
3712 loop optimization twice, the first pass often converts simple
3713 loops into this form. */
3715 if (REG_P (initial_value))
3721 reg1 = initial_value;
3722 if (GET_CODE (final_value) == PLUS)
3723 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3725 reg2 = final_value, const2 = const0_rtx;
3727 /* Check for initial_value = reg1, final_value = reg2 + const2,
3728 where reg1 != reg2. */
3729 if (REG_P (reg2) && reg2 != reg1)
3733 /* Find what reg1 is equivalent to. Hopefully it will
3734 either be reg2 or reg2 plus a constant. */
3735 temp = loop_find_equiv_value (loop_start, reg1);
3736 if (find_common_reg_term (temp, reg2))
3737 initial_value = temp;
3740 /* Find what reg2 is equivalent to. Hopefully it will
3741 either be reg1 or reg1 plus a constant. Let's ignore
3742 the latter case for now since it is not so common. */
3743 temp = loop_find_equiv_value (loop_start, reg2);
3744 if (temp == loop_info->iteration_var)
3745 temp = initial_value;
3747 final_value = (const2 == const0_rtx)
3748 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3751 else if (loop_info->vtop && GET_CODE (reg2) == CONST_INT)
3755 /* When running the loop optimizer twice, check_dbra_loop
3756 further obfuscates reversible loops of the form:
3757 for (i = init; i < init + const; i++). We often end up with
3758 final_value = 0, initial_value = temp, temp = temp2 - init,
3759 where temp2 = init + const. If the loop has a vtop we
3760 can replace initial_value with const. */
3762 temp = loop_find_equiv_value (loop_start, reg1);
3763 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3765 rtx temp2 = loop_find_equiv_value (loop_start, XEXP (temp, 0));
3766 if (GET_CODE (temp2) == PLUS
3767 && XEXP (temp2, 0) == XEXP (temp, 1))
3768 initial_value = XEXP (temp2, 1);
3773 /* If have initial_value = reg + const1 and final_value = reg +
3774 const2, then replace initial_value with const1 and final_value
3775 with const2. This should be safe since we are protected by the
3776 initial comparison before entering the loop if we have a vtop.
3777 For example, a + b < a + c is not equivalent to b < c for all a
3778 when using modulo arithmetic.
3780 ??? Without a vtop we could still perform the optimization if we check
3781 the initial and final values carefully. */
3783 && (reg_term = find_common_reg_term (initial_value, final_value)))
3785 initial_value = subtract_reg_term (initial_value, reg_term);
3786 final_value = subtract_reg_term (final_value, reg_term);
3789 loop_info->initial_equiv_value = initial_value;
3790 loop_info->final_equiv_value = final_value;
3794 if (loop_dump_stream)
3795 fprintf (loop_dump_stream,
3796 "Loop iterations: Increment value can't be calculated.\n");
3800 if (GET_CODE (increment) != CONST_INT)
3802 increment = loop_find_equiv_value (loop_start, increment);
3804 if (GET_CODE (increment) != CONST_INT)
3806 if (loop_dump_stream)
3808 fprintf (loop_dump_stream,
3809 "Loop iterations: Increment value not constant ");
3810 print_rtl (loop_dump_stream, increment);
3811 fprintf (loop_dump_stream, ".\n");
3815 loop_info->increment = increment;
3818 if (GET_CODE (initial_value) != CONST_INT)
3820 if (loop_dump_stream)
3822 fprintf (loop_dump_stream,
3823 "Loop iterations: Initial value not constant ");
3824 print_rtl (loop_dump_stream, initial_value);
3825 fprintf (loop_dump_stream, ".\n");
3829 else if (comparison_code == EQ)
3831 if (loop_dump_stream)
3832 fprintf (loop_dump_stream,
3833 "Loop iterations: EQ comparison loop.\n");
3836 else if (GET_CODE (final_value) != CONST_INT)
3838 if (loop_dump_stream)
3840 fprintf (loop_dump_stream,
3841 "Loop iterations: Final value not constant ");
3842 print_rtl (loop_dump_stream, final_value);
3843 fprintf (loop_dump_stream, ".\n");
3848 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3851 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3852 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3853 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3854 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3856 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3857 - (INTVAL (final_value) < INTVAL (initial_value));
3859 if (INTVAL (increment) > 0)
3861 else if (INTVAL (increment) == 0)
3866 /* There are 27 different cases: compare_dir = -1, 0, 1;
3867 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3868 There are 4 normal cases, 4 reverse cases (where the iteration variable
3869 will overflow before the loop exits), 4 infinite loop cases, and 15
3870 immediate exit (0 or 1 iteration depending on loop type) cases.
3871 Only try to optimize the normal cases. */
3873 /* (compare_dir/final_larger/increment_dir)
3874 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3875 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3876 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3877 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3879 /* ?? If the meaning of reverse loops (where the iteration variable
3880 will overflow before the loop exits) is undefined, then could
3881 eliminate all of these special checks, and just always assume
3882 the loops are normal/immediate/infinite. Note that this means
3883 the sign of increment_dir does not have to be known. Also,
3884 since it does not really hurt if immediate exit loops or infinite loops
3885 are optimized, then that case could be ignored also, and hence all
3886 loops can be optimized.
3888 According to ANSI Spec, the reverse loop case result is undefined,
3889 because the action on overflow is undefined.
3891 See also the special test for NE loops below. */
3893 if (final_larger == increment_dir && final_larger != 0
3894 && (final_larger == compare_dir || compare_dir == 0))
3899 if (loop_dump_stream)
3900 fprintf (loop_dump_stream,
3901 "Loop iterations: Not normal loop.\n");
3905 /* Calculate the number of iterations, final_value is only an approximation,
3906 so correct for that. Note that abs_diff and n_iterations are
3907 unsigned, because they can be as large as 2^n - 1. */
3909 abs_inc = INTVAL (increment);
3911 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
3912 else if (abs_inc < 0)
3914 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
3920 /* For NE tests, make sure that the iteration variable won't miss
3921 the final value. If abs_diff mod abs_incr is not zero, then the
3922 iteration variable will overflow before the loop exits, and we
3923 can not calculate the number of iterations. */
3924 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
3927 /* Note that the number of iterations could be calculated using
3928 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3929 handle potential overflow of the summation. */
3930 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
3931 return loop_info->n_iterations;
3935 /* Replace uses of split bivs with their split pseudo register. This is
3936 for original instructions which remain after loop unrolling without
3940 remap_split_bivs (x)
3943 register enum rtx_code code;
3950 code = GET_CODE (x);
3965 /* If non-reduced/final-value givs were split, then this would also
3966 have to remap those givs also. */
3968 if (REGNO (x) < max_reg_before_loop
3969 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
3970 return reg_biv_class[REGNO (x)]->biv->src_reg;
3977 fmt = GET_RTX_FORMAT (code);
3978 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3981 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
3985 for (j = 0; j < XVECLEN (x, i); j++)
3986 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
3992 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3993 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3994 return 0. COPY_START is where we can start looking for the insns
3995 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3998 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3999 must dominate LAST_UID.
4001 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4002 may not dominate LAST_UID.
4004 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4005 must dominate LAST_UID. */
4008 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4015 int passed_jump = 0;
4016 rtx p = NEXT_INSN (copy_start);
4018 while (INSN_UID (p) != first_uid)
4020 if (GET_CODE (p) == JUMP_INSN)
4022 /* Could not find FIRST_UID. */
4028 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4029 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
4030 || ! dead_or_set_regno_p (p, regno))
4033 /* FIRST_UID is always executed. */
4034 if (passed_jump == 0)
4037 while (INSN_UID (p) != last_uid)
4039 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4040 can not be sure that FIRST_UID dominates LAST_UID. */
4041 if (GET_CODE (p) == CODE_LABEL)
4043 /* Could not find LAST_UID, but we reached the end of the loop, so
4045 else if (p == copy_end)
4050 /* FIRST_UID is always executed if LAST_UID is executed. */