1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000 Free Software
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor { int factor, count; } factors[NUM_FACTORS]
144 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
148 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
153 #include "insn-config.h"
154 #include "integrate.h"
162 /* This controls which loops are unrolled, and by how much we unroll
165 #ifndef MAX_UNROLLED_INSNS
166 #define MAX_UNROLLED_INSNS 100
169 /* Indexed by register number, if non-zero, then it contains a pointer
170 to a struct induction for a DEST_REG giv which has been combined with
171 one of more address givs. This is needed because whenever such a DEST_REG
172 giv is modified, we must modify the value of all split address givs
173 that were combined with this DEST_REG giv. */
175 static struct induction **addr_combined_regs;
177 /* Indexed by register number, if this is a splittable induction variable,
178 then this will hold the current value of the register, which depends on the
181 static rtx *splittable_regs;
183 /* Indexed by register number, if this is a splittable induction variable,
184 this indicates if it was made from a derived giv. */
185 static char *derived_regs;
187 /* Indexed by register number, if this is a splittable induction variable,
188 then this will hold the number of instructions in the loop that modify
189 the induction variable. Used to ensure that only the last insn modifying
190 a split iv will update the original iv of the dest. */
192 static int *splittable_regs_updates;
194 /* Forward declarations. */
196 static void init_reg_map PROTO((struct inline_remap *, int));
197 static rtx calculate_giv_inc PROTO((rtx, rtx, int));
198 static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
199 static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
200 static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
201 enum unroll_types, rtx, rtx, rtx, rtx));
202 static void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
203 static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int,
204 unsigned HOST_WIDE_INT));
205 static int find_splittable_givs PROTO((struct iv_class *, enum unroll_types,
206 rtx, rtx, rtx, int));
207 static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
208 static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
209 static int verify_addresses PROTO((struct induction *, rtx, int));
210 static rtx remap_split_bivs PROTO((rtx));
212 /* Try to unroll one loop and split induction variables in the loop.
214 The loop is described by the arguments LOOP_END, INSN_COUNT, and
215 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
216 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
217 indicates whether information generated in the strength reduction pass
220 This function is intended to be called from within `strength_reduce'
224 unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
225 loop_info, strength_reduce_p)
229 rtx end_insert_before;
230 struct loop_info *loop_info;
231 int strength_reduce_p;
234 int unroll_number = 1;
235 rtx copy_start, copy_end;
236 rtx insn, sequence, pattern, tem;
237 int max_labelno, max_insnno;
239 struct inline_remap *map;
242 int max_local_regnum;
247 int splitting_not_safe = 0;
248 enum unroll_types unroll_type;
249 int loop_preconditioned = 0;
251 /* This points to the last real insn in the loop, which should be either
252 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
256 /* Don't bother unrolling huge loops. Since the minimum factor is
257 two, loops greater than one half of MAX_UNROLLED_INSNS will never
259 if (insn_count > MAX_UNROLLED_INSNS / 2)
261 if (loop_dump_stream)
262 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
266 /* When emitting debugger info, we can't unroll loops with unequal numbers
267 of block_beg and block_end notes, because that would unbalance the block
268 structure of the function. This can happen as a result of the
269 "if (foo) bar; else break;" optimization in jump.c. */
270 /* ??? Gcc has a general policy that -g is never supposed to change the code
271 that the compiler emits, so we must disable this optimization always,
272 even if debug info is not being output. This is rare, so this should
273 not be a significant performance problem. */
275 if (1 /* write_symbols != NO_DEBUG */)
277 int block_begins = 0;
280 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
282 if (GET_CODE (insn) == NOTE)
284 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
286 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
291 if (block_begins != block_ends)
293 if (loop_dump_stream)
294 fprintf (loop_dump_stream,
295 "Unrolling failure: Unbalanced block notes.\n");
300 /* Determine type of unroll to perform. Depends on the number of iterations
301 and the size of the loop. */
303 /* If there is no strength reduce info, then set
304 loop_info->n_iterations to zero. This can happen if
305 strength_reduce can't find any bivs in the loop. A value of zero
306 indicates that the number of iterations could not be calculated. */
308 if (! strength_reduce_p)
309 loop_info->n_iterations = 0;
311 if (loop_dump_stream && loop_info->n_iterations > 0)
313 fputs ("Loop unrolling: ", loop_dump_stream);
314 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
315 loop_info->n_iterations);
316 fputs (" iterations.\n", loop_dump_stream);
319 /* Find and save a pointer to the last nonnote insn in the loop. */
321 last_loop_insn = prev_nonnote_insn (loop_end);
323 /* Calculate how many times to unroll the loop. Indicate whether or
324 not the loop is being completely unrolled. */
326 if (loop_info->n_iterations == 1)
328 /* If number of iterations is exactly 1, then eliminate the compare and
329 branch at the end of the loop since they will never be taken.
330 Then return, since no other action is needed here. */
332 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
333 don't do anything. */
335 if (GET_CODE (last_loop_insn) == BARRIER)
337 /* Delete the jump insn. This will delete the barrier also. */
338 delete_insn (PREV_INSN (last_loop_insn));
340 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
343 /* The immediately preceding insn is a compare which must be
345 delete_insn (last_loop_insn);
346 delete_insn (PREV_INSN (last_loop_insn));
348 /* The immediately preceding insn may not be the compare, so don't
350 delete_insn (last_loop_insn);
355 else if (loop_info->n_iterations > 0
356 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
358 unroll_number = loop_info->n_iterations;
359 unroll_type = UNROLL_COMPLETELY;
361 else if (loop_info->n_iterations > 0)
363 /* Try to factor the number of iterations. Don't bother with the
364 general case, only using 2, 3, 5, and 7 will get 75% of all
365 numbers theoretically, and almost all in practice. */
367 for (i = 0; i < NUM_FACTORS; i++)
368 factors[i].count = 0;
370 temp = loop_info->n_iterations;
371 for (i = NUM_FACTORS - 1; i >= 0; i--)
372 while (temp % factors[i].factor == 0)
375 temp = temp / factors[i].factor;
378 /* Start with the larger factors first so that we generally
379 get lots of unrolling. */
383 for (i = 3; i >= 0; i--)
384 while (factors[i].count--)
386 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
388 unroll_number *= factors[i].factor;
389 temp *= factors[i].factor;
395 /* If we couldn't find any factors, then unroll as in the normal
397 if (unroll_number == 1)
399 if (loop_dump_stream)
400 fprintf (loop_dump_stream,
401 "Loop unrolling: No factors found.\n");
404 unroll_type = UNROLL_MODULO;
408 /* Default case, calculate number of times to unroll loop based on its
410 if (unroll_number == 1)
412 if (8 * insn_count < MAX_UNROLLED_INSNS)
414 else if (4 * insn_count < MAX_UNROLLED_INSNS)
419 unroll_type = UNROLL_NAIVE;
422 /* Now we know how many times to unroll the loop. */
424 if (loop_dump_stream)
425 fprintf (loop_dump_stream,
426 "Unrolling loop %d times.\n", unroll_number);
429 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
431 /* Loops of these types can start with jump down to the exit condition
432 in rare circumstances.
434 Consider a pair of nested loops where the inner loop is part
435 of the exit code for the outer loop.
437 In this case jump.c will not duplicate the exit test for the outer
438 loop, so it will start with a jump to the exit code.
440 Then consider if the inner loop turns out to iterate once and
441 only once. We will end up deleting the jumps associated with
442 the inner loop. However, the loop notes are not removed from
443 the instruction stream.
445 And finally assume that we can compute the number of iterations
448 In this case unroll may want to unroll the outer loop even though
449 it starts with a jump to the outer loop's exit code.
451 We could try to optimize this case, but it hardly seems worth it.
452 Just return without unrolling the loop in such cases. */
455 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
456 insn = NEXT_INSN (insn);
457 if (GET_CODE (insn) == JUMP_INSN)
461 if (unroll_type == UNROLL_COMPLETELY)
463 /* Completely unrolling the loop: Delete the compare and branch at
464 the end (the last two instructions). This delete must done at the
465 very end of loop unrolling, to avoid problems with calls to
466 back_branch_in_range_p, which is called by find_splittable_regs.
467 All increments of splittable bivs/givs are changed to load constant
470 copy_start = loop_start;
472 /* Set insert_before to the instruction immediately after the JUMP_INSN
473 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
474 the loop will be correctly handled by copy_loop_body. */
475 insert_before = NEXT_INSN (last_loop_insn);
477 /* Set copy_end to the insn before the jump at the end of the loop. */
478 if (GET_CODE (last_loop_insn) == BARRIER)
479 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
480 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
483 /* The instruction immediately before the JUMP_INSN is a compare
484 instruction which we do not want to copy. */
485 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
487 /* The instruction immediately before the JUMP_INSN may not be the
488 compare, so we must copy it. */
489 copy_end = PREV_INSN (last_loop_insn);
494 /* We currently can't unroll a loop if it doesn't end with a
495 JUMP_INSN. There would need to be a mechanism that recognizes
496 this case, and then inserts a jump after each loop body, which
497 jumps to after the last loop body. */
498 if (loop_dump_stream)
499 fprintf (loop_dump_stream,
500 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
504 else if (unroll_type == UNROLL_MODULO)
506 /* Partially unrolling the loop: The compare and branch at the end
507 (the last two instructions) must remain. Don't copy the compare
508 and branch instructions at the end of the loop. Insert the unrolled
509 code immediately before the compare/branch at the end so that the
510 code will fall through to them as before. */
512 copy_start = loop_start;
514 /* Set insert_before to the jump insn at the end of the loop.
515 Set copy_end to before the jump insn at the end of the loop. */
516 if (GET_CODE (last_loop_insn) == BARRIER)
518 insert_before = PREV_INSN (last_loop_insn);
519 copy_end = PREV_INSN (insert_before);
521 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
524 /* The instruction immediately before the JUMP_INSN is a compare
525 instruction which we do not want to copy or delete. */
526 insert_before = PREV_INSN (last_loop_insn);
527 copy_end = PREV_INSN (insert_before);
529 /* The instruction immediately before the JUMP_INSN may not be the
530 compare, so we must copy it. */
531 insert_before = last_loop_insn;
532 copy_end = PREV_INSN (last_loop_insn);
537 /* We currently can't unroll a loop if it doesn't end with a
538 JUMP_INSN. There would need to be a mechanism that recognizes
539 this case, and then inserts a jump after each loop body, which
540 jumps to after the last loop body. */
541 if (loop_dump_stream)
542 fprintf (loop_dump_stream,
543 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
549 /* Normal case: Must copy the compare and branch instructions at the
552 if (GET_CODE (last_loop_insn) == BARRIER)
554 /* Loop ends with an unconditional jump and a barrier.
555 Handle this like above, don't copy jump and barrier.
556 This is not strictly necessary, but doing so prevents generating
557 unconditional jumps to an immediately following label.
559 This will be corrected below if the target of this jump is
560 not the start_label. */
562 insert_before = PREV_INSN (last_loop_insn);
563 copy_end = PREV_INSN (insert_before);
565 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
567 /* Set insert_before to immediately after the JUMP_INSN, so that
568 NOTEs at the end of the loop will be correctly handled by
570 insert_before = NEXT_INSN (last_loop_insn);
571 copy_end = last_loop_insn;
575 /* We currently can't unroll a loop if it doesn't end with a
576 JUMP_INSN. There would need to be a mechanism that recognizes
577 this case, and then inserts a jump after each loop body, which
578 jumps to after the last loop body. */
579 if (loop_dump_stream)
580 fprintf (loop_dump_stream,
581 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
585 /* If copying exit test branches because they can not be eliminated,
586 then must convert the fall through case of the branch to a jump past
587 the end of the loop. Create a label to emit after the loop and save
588 it for later use. Do not use the label after the loop, if any, since
589 it might be used by insns outside the loop, or there might be insns
590 added before it later by final_[bg]iv_value which must be after
591 the real exit label. */
592 exit_label = gen_label_rtx ();
595 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
596 insn = NEXT_INSN (insn);
598 if (GET_CODE (insn) == JUMP_INSN)
600 /* The loop starts with a jump down to the exit condition test.
601 Start copying the loop after the barrier following this
603 copy_start = NEXT_INSN (insn);
605 /* Splitting induction variables doesn't work when the loop is
606 entered via a jump to the bottom, because then we end up doing
607 a comparison against a new register for a split variable, but
608 we did not execute the set insn for the new register because
609 it was skipped over. */
610 splitting_not_safe = 1;
611 if (loop_dump_stream)
612 fprintf (loop_dump_stream,
613 "Splitting not safe, because loop not entered at top.\n");
616 copy_start = loop_start;
619 /* This should always be the first label in the loop. */
620 start_label = NEXT_INSN (copy_start);
621 /* There may be a line number note and/or a loop continue note here. */
622 while (GET_CODE (start_label) == NOTE)
623 start_label = NEXT_INSN (start_label);
624 if (GET_CODE (start_label) != CODE_LABEL)
626 /* This can happen as a result of jump threading. If the first insns in
627 the loop test the same condition as the loop's backward jump, or the
628 opposite condition, then the backward jump will be modified to point
629 to elsewhere, and the loop's start label is deleted.
631 This case currently can not be handled by the loop unrolling code. */
633 if (loop_dump_stream)
634 fprintf (loop_dump_stream,
635 "Unrolling failure: unknown insns between BEG note and loop label.\n");
638 if (LABEL_NAME (start_label))
640 /* The jump optimization pass must have combined the original start label
641 with a named label for a goto. We can't unroll this case because
642 jumps which go to the named label must be handled differently than
643 jumps to the loop start, and it is impossible to differentiate them
645 if (loop_dump_stream)
646 fprintf (loop_dump_stream,
647 "Unrolling failure: loop start label is gone\n");
651 if (unroll_type == UNROLL_NAIVE
652 && GET_CODE (last_loop_insn) == BARRIER
653 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
655 /* In this case, we must copy the jump and barrier, because they will
656 not be converted to jumps to an immediately following label. */
658 insert_before = NEXT_INSN (last_loop_insn);
659 copy_end = last_loop_insn;
662 if (unroll_type == UNROLL_NAIVE
663 && GET_CODE (last_loop_insn) == JUMP_INSN
664 && start_label != JUMP_LABEL (last_loop_insn))
666 /* ??? The loop ends with a conditional branch that does not branch back
667 to the loop start label. In this case, we must emit an unconditional
668 branch to the loop exit after emitting the final branch.
669 copy_loop_body does not have support for this currently, so we
670 give up. It doesn't seem worthwhile to unroll anyways since
671 unrolling would increase the number of branch instructions
673 if (loop_dump_stream)
674 fprintf (loop_dump_stream,
675 "Unrolling failure: final conditional branch not to loop start\n");
679 /* Allocate a translation table for the labels and insn numbers.
680 They will be filled in as we copy the insns in the loop. */
682 max_labelno = max_label_num ();
683 max_insnno = get_max_uid ();
685 map = (struct inline_remap *) alloca (sizeof (struct inline_remap));
687 map->integrating = 0;
688 map->const_equiv_varray = 0;
690 /* Allocate the label map. */
694 map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx));
696 local_label = (char *) alloca (max_labelno);
697 bzero (local_label, max_labelno);
702 /* Search the loop and mark all local labels, i.e. the ones which have to
703 be distinct labels when copied. For all labels which might be
704 non-local, set their label_map entries to point to themselves.
705 If they happen to be local their label_map entries will be overwritten
706 before the loop body is copied. The label_map entries for local labels
707 will be set to a different value each time the loop body is copied. */
709 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
713 if (GET_CODE (insn) == CODE_LABEL)
714 local_label[CODE_LABEL_NUMBER (insn)] = 1;
715 else if (GET_CODE (insn) == JUMP_INSN)
717 if (JUMP_LABEL (insn))
718 set_label_in_map (map,
719 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
721 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
722 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
724 rtx pat = PATTERN (insn);
725 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
726 int len = XVECLEN (pat, diff_vec_p);
729 for (i = 0; i < len; i++)
731 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
732 set_label_in_map (map,
733 CODE_LABEL_NUMBER (label),
738 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
739 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
743 /* Allocate space for the insn map. */
745 map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx));
747 /* Set this to zero, to indicate that we are doing loop unrolling,
748 not function inlining. */
749 map->inline_target = 0;
751 /* The register and constant maps depend on the number of registers
752 present, so the final maps can't be created until after
753 find_splittable_regs is called. However, they are needed for
754 preconditioning, so we create temporary maps when preconditioning
757 /* The preconditioning code may allocate two new pseudo registers. */
758 maxregnum = max_reg_num ();
760 /* local_regno is only valid for regnos < max_local_regnum. */
761 max_local_regnum = maxregnum;
763 /* Allocate and zero out the splittable_regs and addr_combined_regs
764 arrays. These must be zeroed here because they will be used if
765 loop preconditioning is performed, and must be zero for that case.
767 It is safe to do this here, since the extra registers created by the
768 preconditioning code and find_splittable_regs will never be used
769 to access the splittable_regs[] and addr_combined_regs[] arrays. */
771 splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx));
772 bzero ((char *) splittable_regs, maxregnum * sizeof (rtx));
773 derived_regs = alloca (maxregnum);
774 bzero (derived_regs, maxregnum);
775 splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int));
776 bzero ((char *) splittable_regs_updates, maxregnum * sizeof (int));
778 = (struct induction **) alloca (maxregnum * sizeof (struct induction *));
779 bzero ((char *) addr_combined_regs, maxregnum * sizeof (struct induction *));
780 local_regno = (char *) alloca (maxregnum);
781 bzero (local_regno, maxregnum);
783 /* Mark all local registers, i.e. the ones which are referenced only
785 if (INSN_UID (copy_end) < max_uid_for_loop)
787 int copy_start_luid = INSN_LUID (copy_start);
788 int copy_end_luid = INSN_LUID (copy_end);
790 /* If a register is used in the jump insn, we must not duplicate it
791 since it will also be used outside the loop. */
792 if (GET_CODE (copy_end) == JUMP_INSN)
795 /* If we have a target that uses cc0, then we also must not duplicate
796 the insn that sets cc0 before the jump insn. */
798 if (GET_CODE (copy_end) == JUMP_INSN)
802 /* If copy_start points to the NOTE that starts the loop, then we must
803 use the next luid, because invariant pseudo-regs moved out of the loop
804 have their lifetimes modified to start here, but they are not safe
806 if (copy_start == loop_start)
809 /* If a pseudo's lifetime is entirely contained within this loop, then we
810 can use a different pseudo in each unrolled copy of the loop. This
811 results in better code. */
812 /* We must limit the generic test to max_reg_before_loop, because only
813 these pseudo registers have valid regno_first_uid info. */
814 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
815 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
816 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
817 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
818 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
820 /* However, we must also check for loop-carried dependencies.
821 If the value the pseudo has at the end of iteration X is
822 used by iteration X+1, then we can not use a different pseudo
823 for each unrolled copy of the loop. */
824 /* A pseudo is safe if regno_first_uid is a set, and this
825 set dominates all instructions from regno_first_uid to
827 /* ??? This check is simplistic. We would get better code if
828 this check was more sophisticated. */
829 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
830 copy_start, copy_end))
833 if (loop_dump_stream)
836 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
838 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
842 /* Givs that have been created from multiple biv increments always have
844 for (j = first_increment_giv; j <= last_increment_giv; j++)
847 if (loop_dump_stream)
848 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
852 /* If this loop requires exit tests when unrolled, check to see if we
853 can precondition the loop so as to make the exit tests unnecessary.
854 Just like variable splitting, this is not safe if the loop is entered
855 via a jump to the bottom. Also, can not do this if no strength
856 reduce info, because precondition_loop_p uses this info. */
858 /* Must copy the loop body for preconditioning before the following
859 find_splittable_regs call since that will emit insns which need to
860 be after the preconditioned loop copies, but immediately before the
861 unrolled loop copies. */
863 /* Also, it is not safe to split induction variables for the preconditioned
864 copies of the loop body. If we split induction variables, then the code
865 assumes that each induction variable can be represented as a function
866 of its initial value and the loop iteration number. This is not true
867 in this case, because the last preconditioned copy of the loop body
868 could be any iteration from the first up to the `unroll_number-1'th,
869 depending on the initial value of the iteration variable. Therefore
870 we can not split induction variables here, because we can not calculate
871 their value. Hence, this code must occur before find_splittable_regs
874 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
876 rtx initial_value, final_value, increment;
877 enum machine_mode mode;
879 if (precondition_loop_p (loop_start, loop_info,
880 &initial_value, &final_value, &increment,
885 int abs_inc, neg_inc;
887 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
889 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray, maxregnum,
891 global_const_equiv_varray = map->const_equiv_varray;
893 init_reg_map (map, maxregnum);
895 /* Limit loop unrolling to 4, since this will make 7 copies of
897 if (unroll_number > 4)
900 /* Save the absolute value of the increment, and also whether or
901 not it is negative. */
903 abs_inc = INTVAL (increment);
912 /* Calculate the difference between the final and initial values.
913 Final value may be a (plus (reg x) (const_int 1)) rtx.
914 Let the following cse pass simplify this if initial value is
917 We must copy the final and initial values here to avoid
918 improperly shared rtl. */
920 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
921 copy_rtx (initial_value), NULL_RTX, 0,
924 /* Now calculate (diff % (unroll * abs (increment))) by using an
926 diff = expand_binop (GET_MODE (diff), and_optab, diff,
927 GEN_INT (unroll_number * abs_inc - 1),
928 NULL_RTX, 0, OPTAB_LIB_WIDEN);
930 /* Now emit a sequence of branches to jump to the proper precond
933 labels = (rtx *) alloca (sizeof (rtx) * unroll_number);
934 for (i = 0; i < unroll_number; i++)
935 labels[i] = gen_label_rtx ();
937 /* Check for the case where the initial value is greater than or
938 equal to the final value. In that case, we want to execute
939 exactly one loop iteration. The code below will fail for this
940 case. This check does not apply if the loop has a NE
941 comparison at the end. */
943 if (loop_info->comparison_code != NE)
945 emit_cmp_and_jump_insns (initial_value, final_value,
947 NULL_RTX, mode, 0, 0, labels[1]);
948 JUMP_LABEL (get_last_insn ()) = labels[1];
949 LABEL_NUSES (labels[1])++;
952 /* Assuming the unroll_number is 4, and the increment is 2, then
953 for a negative increment: for a positive increment:
954 diff = 0,1 precond 0 diff = 0,7 precond 0
955 diff = 2,3 precond 3 diff = 1,2 precond 1
956 diff = 4,5 precond 2 diff = 3,4 precond 2
957 diff = 6,7 precond 1 diff = 5,6 precond 3 */
959 /* We only need to emit (unroll_number - 1) branches here, the
960 last case just falls through to the following code. */
962 /* ??? This would give better code if we emitted a tree of branches
963 instead of the current linear list of branches. */
965 for (i = 0; i < unroll_number - 1; i++)
968 enum rtx_code cmp_code;
970 /* For negative increments, must invert the constant compared
971 against, except when comparing against zero. */
979 cmp_const = unroll_number - i;
988 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
989 cmp_code, NULL_RTX, mode, 0, 0,
991 JUMP_LABEL (get_last_insn ()) = labels[i];
992 LABEL_NUSES (labels[i])++;
995 /* If the increment is greater than one, then we need another branch,
996 to handle other cases equivalent to 0. */
998 /* ??? This should be merged into the code above somehow to help
999 simplify the code here, and reduce the number of branches emitted.
1000 For the negative increment case, the branch here could easily
1001 be merged with the `0' case branch above. For the positive
1002 increment case, it is not clear how this can be simplified. */
1007 enum rtx_code cmp_code;
1011 cmp_const = abs_inc - 1;
1016 cmp_const = abs_inc * (unroll_number - 1) + 1;
1020 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1021 NULL_RTX, mode, 0, 0, labels[0]);
1022 JUMP_LABEL (get_last_insn ()) = labels[0];
1023 LABEL_NUSES (labels[0])++;
1026 sequence = gen_sequence ();
1028 emit_insn_before (sequence, loop_start);
1030 /* Only the last copy of the loop body here needs the exit
1031 test, so set copy_end to exclude the compare/branch here,
1032 and then reset it inside the loop when get to the last
1035 if (GET_CODE (last_loop_insn) == BARRIER)
1036 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1037 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1040 /* The immediately preceding insn is a compare which we do not
1042 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1044 /* The immediately preceding insn may not be a compare, so we
1046 copy_end = PREV_INSN (last_loop_insn);
1052 for (i = 1; i < unroll_number; i++)
1054 emit_label_after (labels[unroll_number - i],
1055 PREV_INSN (loop_start));
1057 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1058 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1059 (VARRAY_SIZE (map->const_equiv_varray)
1060 * sizeof (struct const_equiv_data)));
1063 for (j = 0; j < max_labelno; j++)
1065 set_label_in_map (map, j, gen_label_rtx ());
1067 for (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
1070 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1071 record_base_value (REGNO (map->reg_map[j]),
1072 regno_reg_rtx[j], 0);
1074 /* The last copy needs the compare/branch insns at the end,
1075 so reset copy_end here if the loop ends with a conditional
1078 if (i == unroll_number - 1)
1080 if (GET_CODE (last_loop_insn) == BARRIER)
1081 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1083 copy_end = last_loop_insn;
1086 /* None of the copies are the `last_iteration', so just
1087 pass zero for that parameter. */
1088 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1089 unroll_type, start_label, loop_end,
1090 loop_start, copy_end);
1092 emit_label_after (labels[0], PREV_INSN (loop_start));
1094 if (GET_CODE (last_loop_insn) == BARRIER)
1096 insert_before = PREV_INSN (last_loop_insn);
1097 copy_end = PREV_INSN (insert_before);
1102 /* The immediately preceding insn is a compare which we do not
1104 insert_before = PREV_INSN (last_loop_insn);
1105 copy_end = PREV_INSN (insert_before);
1107 /* The immediately preceding insn may not be a compare, so we
1109 insert_before = last_loop_insn;
1110 copy_end = PREV_INSN (last_loop_insn);
1114 /* Set unroll type to MODULO now. */
1115 unroll_type = UNROLL_MODULO;
1116 loop_preconditioned = 1;
1120 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1121 the loop unless all loops are being unrolled. */
1122 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1124 if (loop_dump_stream)
1125 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1129 /* At this point, we are guaranteed to unroll the loop. */
1131 /* Keep track of the unroll factor for the loop. */
1132 if (unroll_type == UNROLL_COMPLETELY)
1133 loop_info->unroll_number = -1;
1135 loop_info->unroll_number = unroll_number;
1138 /* For each biv and giv, determine whether it can be safely split into
1139 a different variable for each unrolled copy of the loop body.
1140 We precalculate and save this info here, since computing it is
1143 Do this before deleting any instructions from the loop, so that
1144 back_branch_in_range_p will work correctly. */
1146 if (splitting_not_safe)
1149 temp = find_splittable_regs (unroll_type, loop_start, loop_end,
1150 end_insert_before, unroll_number,
1151 loop_info->n_iterations);
1153 /* find_splittable_regs may have created some new registers, so must
1154 reallocate the reg_map with the new larger size, and must realloc
1155 the constant maps also. */
1157 maxregnum = max_reg_num ();
1158 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
1160 init_reg_map (map, maxregnum);
1162 if (map->const_equiv_varray == 0)
1163 VARRAY_CONST_EQUIV_INIT (map->const_equiv_varray,
1164 maxregnum + temp * unroll_number * 2,
1166 global_const_equiv_varray = map->const_equiv_varray;
1168 /* Search the list of bivs and givs to find ones which need to be remapped
1169 when split, and set their reg_map entry appropriately. */
1171 for (bl = loop_iv_list; bl; bl = bl->next)
1173 if (REGNO (bl->biv->src_reg) != bl->regno)
1174 map->reg_map[bl->regno] = bl->biv->src_reg;
1176 /* Currently, non-reduced/final-value givs are never split. */
1177 for (v = bl->giv; v; v = v->next_iv)
1178 if (REGNO (v->src_reg) != bl->regno)
1179 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1183 /* Use our current register alignment and pointer flags. */
1184 map->regno_pointer_flag = regno_pointer_flag;
1185 map->regno_pointer_align = regno_pointer_align;
1187 /* If the loop is being partially unrolled, and the iteration variables
1188 are being split, and are being renamed for the split, then must fix up
1189 the compare/jump instruction at the end of the loop to refer to the new
1190 registers. This compare isn't copied, so the registers used in it
1191 will never be replaced if it isn't done here. */
1193 if (unroll_type == UNROLL_MODULO)
1195 insn = NEXT_INSN (copy_end);
1196 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1197 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1200 /* For unroll_number times, make a copy of each instruction
1201 between copy_start and copy_end, and insert these new instructions
1202 before the end of the loop. */
1204 for (i = 0; i < unroll_number; i++)
1206 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1207 bzero ((char *) &VARRAY_CONST_EQUIV (map->const_equiv_varray, 0),
1208 VARRAY_SIZE (map->const_equiv_varray) * sizeof (struct const_equiv_data));
1211 for (j = 0; j < max_labelno; j++)
1213 set_label_in_map (map, j, gen_label_rtx ());
1215 for (j = FIRST_PSEUDO_REGISTER; j < max_local_regnum; j++)
1218 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1219 record_base_value (REGNO (map->reg_map[j]),
1220 regno_reg_rtx[j], 0);
1223 /* If loop starts with a branch to the test, then fix it so that
1224 it points to the test of the first unrolled copy of the loop. */
1225 if (i == 0 && loop_start != copy_start)
1227 insn = PREV_INSN (copy_start);
1228 pattern = PATTERN (insn);
1230 tem = get_label_from_map (map,
1232 (XEXP (SET_SRC (pattern), 0)));
1233 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1235 /* Set the jump label so that it can be used by later loop unrolling
1237 JUMP_LABEL (insn) = tem;
1238 LABEL_NUSES (tem)++;
1241 copy_loop_body (copy_start, copy_end, map, exit_label,
1242 i == unroll_number - 1, unroll_type, start_label,
1243 loop_end, insert_before, insert_before);
1246 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1247 insn to be deleted. This prevents any runaway delete_insn call from
1248 more insns that it should, as it always stops at a CODE_LABEL. */
1250 /* Delete the compare and branch at the end of the loop if completely
1251 unrolling the loop. Deleting the backward branch at the end also
1252 deletes the code label at the start of the loop. This is done at
1253 the very end to avoid problems with back_branch_in_range_p. */
1255 if (unroll_type == UNROLL_COMPLETELY)
1256 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1258 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1260 /* Delete all of the original loop instructions. Don't delete the
1261 LOOP_BEG note, or the first code label in the loop. */
1263 insn = NEXT_INSN (copy_start);
1264 while (insn != safety_label)
1266 /* ??? Don't delete named code labels. They will be deleted when the
1267 jump that references them is deleted. Otherwise, we end up deleting
1268 them twice, which causes them to completely disappear instead of turn
1269 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1270 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1271 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1272 associated LABEL_DECL to point to one of the new label instances. */
1273 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1274 if (insn != start_label
1275 && ! (GET_CODE (insn) == CODE_LABEL && LABEL_NAME (insn))
1276 && ! (GET_CODE (insn) == NOTE
1277 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_DELETED_LABEL))
1278 insn = delete_insn (insn);
1280 insn = NEXT_INSN (insn);
1283 /* Can now delete the 'safety' label emitted to protect us from runaway
1284 delete_insn calls. */
1285 if (INSN_DELETED_P (safety_label))
1287 delete_insn (safety_label);
1289 /* If exit_label exists, emit it after the loop. Doing the emit here
1290 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1291 This is needed so that mostly_true_jump in reorg.c will treat jumps
1292 to this loop end label correctly, i.e. predict that they are usually
1295 emit_label_after (exit_label, loop_end);
1298 if (map && map->const_equiv_varray)
1299 VARRAY_FREE (map->const_equiv_varray);
1302 /* Return true if the loop can be safely, and profitably, preconditioned
1303 so that the unrolled copies of the loop body don't need exit tests.
1305 This only works if final_value, initial_value and increment can be
1306 determined, and if increment is a constant power of 2.
1307 If increment is not a power of 2, then the preconditioning modulo
1308 operation would require a real modulo instead of a boolean AND, and this
1309 is not considered `profitable'. */
1311 /* ??? If the loop is known to be executed very many times, or the machine
1312 has a very cheap divide instruction, then preconditioning is a win even
1313 when the increment is not a power of 2. Use RTX_COST to compute
1314 whether divide is cheap.
1315 ??? A divide by constant doesn't actually need a divide, look at
1316 expand_divmod. The reduced cost of this optimized modulo is not
1317 reflected in RTX_COST. */
1320 precondition_loop_p (loop_start, loop_info,
1321 initial_value, final_value, increment, mode)
1323 struct loop_info *loop_info;
1324 rtx *initial_value, *final_value, *increment;
1325 enum machine_mode *mode;
1328 if (loop_info->n_iterations > 0)
1330 *initial_value = const0_rtx;
1331 *increment = const1_rtx;
1332 *final_value = GEN_INT (loop_info->n_iterations);
1335 if (loop_dump_stream)
1337 fputs ("Preconditioning: Success, number of iterations known, ",
1339 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1340 loop_info->n_iterations);
1341 fputs (".\n", loop_dump_stream);
1346 if (loop_info->initial_value == 0)
1348 if (loop_dump_stream)
1349 fprintf (loop_dump_stream,
1350 "Preconditioning: Could not find initial value.\n");
1353 else if (loop_info->increment == 0)
1355 if (loop_dump_stream)
1356 fprintf (loop_dump_stream,
1357 "Preconditioning: Could not find increment value.\n");
1360 else if (GET_CODE (loop_info->increment) != CONST_INT)
1362 if (loop_dump_stream)
1363 fprintf (loop_dump_stream,
1364 "Preconditioning: Increment not a constant.\n");
1367 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1368 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1370 if (loop_dump_stream)
1371 fprintf (loop_dump_stream,
1372 "Preconditioning: Increment not a constant power of 2.\n");
1376 /* Unsigned_compare and compare_dir can be ignored here, since they do
1377 not matter for preconditioning. */
1379 if (loop_info->final_value == 0)
1381 if (loop_dump_stream)
1382 fprintf (loop_dump_stream,
1383 "Preconditioning: EQ comparison loop.\n");
1387 /* Must ensure that final_value is invariant, so call invariant_p to
1388 check. Before doing so, must check regno against max_reg_before_loop
1389 to make sure that the register is in the range covered by invariant_p.
1390 If it isn't, then it is most likely a biv/giv which by definition are
1392 if ((GET_CODE (loop_info->final_value) == REG
1393 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1394 || (GET_CODE (loop_info->final_value) == PLUS
1395 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1396 || ! invariant_p (loop_info->final_value))
1398 if (loop_dump_stream)
1399 fprintf (loop_dump_stream,
1400 "Preconditioning: Final value not invariant.\n");
1404 /* Fail for floating point values, since the caller of this function
1405 does not have code to deal with them. */
1406 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1407 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1409 if (loop_dump_stream)
1410 fprintf (loop_dump_stream,
1411 "Preconditioning: Floating point final or initial value.\n");
1415 /* Fail if loop_info->iteration_var is not live before loop_start,
1416 since we need to test its value in the preconditioning code. */
1418 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1419 > INSN_LUID (loop_start))
1421 if (loop_dump_stream)
1422 fprintf (loop_dump_stream,
1423 "Preconditioning: Iteration var not live before loop start.\n");
1427 /* Note that iteration_info biases the initial value for GIV iterators
1428 such as "while (i-- > 0)" so that we can calculate the number of
1429 iterations just like for BIV iterators.
1431 Also note that the absolute values of initial_value and
1432 final_value are unimportant as only their difference is used for
1433 calculating the number of loop iterations. */
1434 *initial_value = loop_info->initial_value;
1435 *increment = loop_info->increment;
1436 *final_value = loop_info->final_value;
1438 /* Decide what mode to do these calculations in. Choose the larger
1439 of final_value's mode and initial_value's mode, or a full-word if
1440 both are constants. */
1441 *mode = GET_MODE (*final_value);
1442 if (*mode == VOIDmode)
1444 *mode = GET_MODE (*initial_value);
1445 if (*mode == VOIDmode)
1448 else if (*mode != GET_MODE (*initial_value)
1449 && (GET_MODE_SIZE (*mode)
1450 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1451 *mode = GET_MODE (*initial_value);
1454 if (loop_dump_stream)
1455 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1460 /* All pseudo-registers must be mapped to themselves. Two hard registers
1461 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1462 REGNUM, to avoid function-inlining specific conversions of these
1463 registers. All other hard regs can not be mapped because they may be
1468 init_reg_map (map, maxregnum)
1469 struct inline_remap *map;
1474 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1475 map->reg_map[i] = regno_reg_rtx[i];
1476 /* Just clear the rest of the entries. */
1477 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1478 map->reg_map[i] = 0;
1480 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1481 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1482 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1483 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1486 /* Strength-reduction will often emit code for optimized biv/givs which
1487 calculates their value in a temporary register, and then copies the result
1488 to the iv. This procedure reconstructs the pattern computing the iv;
1489 verifying that all operands are of the proper form.
1491 PATTERN must be the result of single_set.
1492 The return value is the amount that the giv is incremented by. */
1495 calculate_giv_inc (pattern, src_insn, regno)
1496 rtx pattern, src_insn;
1500 rtx increment_total = 0;
1504 /* Verify that we have an increment insn here. First check for a plus
1505 as the set source. */
1506 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1508 /* SR sometimes computes the new giv value in a temp, then copies it
1510 src_insn = PREV_INSN (src_insn);
1511 pattern = PATTERN (src_insn);
1512 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1515 /* The last insn emitted is not needed, so delete it to avoid confusing
1516 the second cse pass. This insn sets the giv unnecessarily. */
1517 delete_insn (get_last_insn ());
1520 /* Verify that we have a constant as the second operand of the plus. */
1521 increment = XEXP (SET_SRC (pattern), 1);
1522 if (GET_CODE (increment) != CONST_INT)
1524 /* SR sometimes puts the constant in a register, especially if it is
1525 too big to be an add immed operand. */
1526 src_insn = PREV_INSN (src_insn);
1527 increment = SET_SRC (PATTERN (src_insn));
1529 /* SR may have used LO_SUM to compute the constant if it is too large
1530 for a load immed operand. In this case, the constant is in operand
1531 one of the LO_SUM rtx. */
1532 if (GET_CODE (increment) == LO_SUM)
1533 increment = XEXP (increment, 1);
1535 /* Some ports store large constants in memory and add a REG_EQUAL
1536 note to the store insn. */
1537 else if (GET_CODE (increment) == MEM)
1539 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1541 increment = XEXP (note, 0);
1544 else if (GET_CODE (increment) == IOR
1545 || GET_CODE (increment) == ASHIFT
1546 || GET_CODE (increment) == PLUS)
1548 /* The rs6000 port loads some constants with IOR.
1549 The alpha port loads some constants with ASHIFT and PLUS. */
1550 rtx second_part = XEXP (increment, 1);
1551 enum rtx_code code = GET_CODE (increment);
1553 src_insn = PREV_INSN (src_insn);
1554 increment = SET_SRC (PATTERN (src_insn));
1555 /* Don't need the last insn anymore. */
1556 delete_insn (get_last_insn ());
1558 if (GET_CODE (second_part) != CONST_INT
1559 || GET_CODE (increment) != CONST_INT)
1563 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1564 else if (code == PLUS)
1565 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1567 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1570 if (GET_CODE (increment) != CONST_INT)
1573 /* The insn loading the constant into a register is no longer needed,
1575 delete_insn (get_last_insn ());
1578 if (increment_total)
1579 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1581 increment_total = increment;
1583 /* Check that the source register is the same as the register we expected
1584 to see as the source. If not, something is seriously wrong. */
1585 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1586 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1588 /* Some machines (e.g. the romp), may emit two add instructions for
1589 certain constants, so lets try looking for another add immediately
1590 before this one if we have only seen one add insn so far. */
1596 src_insn = PREV_INSN (src_insn);
1597 pattern = PATTERN (src_insn);
1599 delete_insn (get_last_insn ());
1607 return increment_total;
1610 /* Copy REG_NOTES, except for insn references, because not all insn_map
1611 entries are valid yet. We do need to copy registers now though, because
1612 the reg_map entries can change during copying. */
1615 initial_reg_note_copy (notes, map)
1617 struct inline_remap *map;
1624 copy = rtx_alloc (GET_CODE (notes));
1625 PUT_MODE (copy, GET_MODE (notes));
1627 if (GET_CODE (notes) == EXPR_LIST)
1628 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map);
1629 else if (GET_CODE (notes) == INSN_LIST)
1630 /* Don't substitute for these yet. */
1631 XEXP (copy, 0) = XEXP (notes, 0);
1635 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1640 /* Fixup insn references in copied REG_NOTES. */
1643 final_reg_note_copy (notes, map)
1645 struct inline_remap *map;
1649 for (note = notes; note; note = XEXP (note, 1))
1650 if (GET_CODE (note) == INSN_LIST)
1651 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1654 /* Copy each instruction in the loop, substituting from map as appropriate.
1655 This is very similar to a loop in expand_inline_function. */
1658 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1659 unroll_type, start_label, loop_end, insert_before,
1661 rtx copy_start, copy_end;
1662 struct inline_remap *map;
1665 enum unroll_types unroll_type;
1666 rtx start_label, loop_end, insert_before, copy_notes_from;
1670 int dest_reg_was_split, i;
1674 rtx final_label = 0;
1675 rtx giv_inc, giv_dest_reg, giv_src_reg;
1677 /* If this isn't the last iteration, then map any references to the
1678 start_label to final_label. Final label will then be emitted immediately
1679 after the end of this loop body if it was ever used.
1681 If this is the last iteration, then map references to the start_label
1683 if (! last_iteration)
1685 final_label = gen_label_rtx ();
1686 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1690 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1694 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1695 Else gen_sequence could return a raw pattern for a jump which we pass
1696 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1697 a variety of losing behaviors later. */
1698 emit_note (0, NOTE_INSN_DELETED);
1703 insn = NEXT_INSN (insn);
1705 map->orig_asm_operands_vector = 0;
1707 switch (GET_CODE (insn))
1710 pattern = PATTERN (insn);
1714 /* Check to see if this is a giv that has been combined with
1715 some split address givs. (Combined in the sense that
1716 `combine_givs' in loop.c has put two givs in the same register.)
1717 In this case, we must search all givs based on the same biv to
1718 find the address givs. Then split the address givs.
1719 Do this before splitting the giv, since that may map the
1720 SET_DEST to a new register. */
1722 if ((set = single_set (insn))
1723 && GET_CODE (SET_DEST (set)) == REG
1724 && addr_combined_regs[REGNO (SET_DEST (set))])
1726 struct iv_class *bl;
1727 struct induction *v, *tv;
1728 int regno = REGNO (SET_DEST (set));
1730 v = addr_combined_regs[REGNO (SET_DEST (set))];
1731 bl = reg_biv_class[REGNO (v->src_reg)];
1733 /* Although the giv_inc amount is not needed here, we must call
1734 calculate_giv_inc here since it might try to delete the
1735 last insn emitted. If we wait until later to call it,
1736 we might accidentally delete insns generated immediately
1737 below by emit_unrolled_add. */
1739 if (! derived_regs[regno])
1740 giv_inc = calculate_giv_inc (set, insn, regno);
1742 /* Now find all address giv's that were combined with this
1744 for (tv = bl->giv; tv; tv = tv->next_iv)
1745 if (tv->giv_type == DEST_ADDR && tv->same == v)
1749 /* If this DEST_ADDR giv was not split, then ignore it. */
1750 if (*tv->location != tv->dest_reg)
1753 /* Scale this_giv_inc if the multiplicative factors of
1754 the two givs are different. */
1755 this_giv_inc = INTVAL (giv_inc);
1756 if (tv->mult_val != v->mult_val)
1757 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1758 * INTVAL (tv->mult_val));
1760 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1761 *tv->location = tv->dest_reg;
1763 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1765 /* Must emit an insn to increment the split address
1766 giv. Add in the const_adjust field in case there
1767 was a constant eliminated from the address. */
1768 rtx value, dest_reg;
1770 /* tv->dest_reg will be either a bare register,
1771 or else a register plus a constant. */
1772 if (GET_CODE (tv->dest_reg) == REG)
1773 dest_reg = tv->dest_reg;
1775 dest_reg = XEXP (tv->dest_reg, 0);
1777 /* Check for shared address givs, and avoid
1778 incrementing the shared pseudo reg more than
1780 if (! tv->same_insn && ! tv->shared)
1782 /* tv->dest_reg may actually be a (PLUS (REG)
1783 (CONST)) here, so we must call plus_constant
1784 to add the const_adjust amount before calling
1785 emit_unrolled_add below. */
1786 value = plus_constant (tv->dest_reg,
1789 /* The constant could be too large for an add
1790 immediate, so can't directly emit an insn
1792 emit_unrolled_add (dest_reg, XEXP (value, 0),
1796 /* Reset the giv to be just the register again, in case
1797 it is used after the set we have just emitted.
1798 We must subtract the const_adjust factor added in
1800 tv->dest_reg = plus_constant (dest_reg,
1801 - tv->const_adjust);
1802 *tv->location = tv->dest_reg;
1807 /* If this is a setting of a splittable variable, then determine
1808 how to split the variable, create a new set based on this split,
1809 and set up the reg_map so that later uses of the variable will
1810 use the new split variable. */
1812 dest_reg_was_split = 0;
1814 if ((set = single_set (insn))
1815 && GET_CODE (SET_DEST (set)) == REG
1816 && splittable_regs[REGNO (SET_DEST (set))])
1818 int regno = REGNO (SET_DEST (set));
1821 dest_reg_was_split = 1;
1823 giv_dest_reg = SET_DEST (set);
1824 if (derived_regs[regno])
1826 /* ??? This relies on SET_SRC (SET) to be of
1827 the form (plus (reg) (const_int)), and thus
1828 forces recombine_givs to restrict the kind
1829 of giv derivations it does before unrolling. */
1830 giv_src_reg = XEXP (SET_SRC (set), 0);
1831 giv_inc = XEXP (SET_SRC (set), 1);
1835 giv_src_reg = giv_dest_reg;
1836 /* Compute the increment value for the giv, if it wasn't
1837 already computed above. */
1839 giv_inc = calculate_giv_inc (set, insn, regno);
1841 src_regno = REGNO (giv_src_reg);
1843 if (unroll_type == UNROLL_COMPLETELY)
1845 /* Completely unrolling the loop. Set the induction
1846 variable to a known constant value. */
1848 /* The value in splittable_regs may be an invariant
1849 value, so we must use plus_constant here. */
1850 splittable_regs[regno]
1851 = plus_constant (splittable_regs[src_regno],
1854 if (GET_CODE (splittable_regs[regno]) == PLUS)
1856 giv_src_reg = XEXP (splittable_regs[regno], 0);
1857 giv_inc = XEXP (splittable_regs[regno], 1);
1861 /* The splittable_regs value must be a REG or a
1862 CONST_INT, so put the entire value in the giv_src_reg
1864 giv_src_reg = splittable_regs[regno];
1865 giv_inc = const0_rtx;
1870 /* Partially unrolling loop. Create a new pseudo
1871 register for the iteration variable, and set it to
1872 be a constant plus the original register. Except
1873 on the last iteration, when the result has to
1874 go back into the original iteration var register. */
1876 /* Handle bivs which must be mapped to a new register
1877 when split. This happens for bivs which need their
1878 final value set before loop entry. The new register
1879 for the biv was stored in the biv's first struct
1880 induction entry by find_splittable_regs. */
1882 if (regno < max_reg_before_loop
1883 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1885 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1886 giv_dest_reg = giv_src_reg;
1890 /* If non-reduced/final-value givs were split, then
1891 this would have to remap those givs also. See
1892 find_splittable_regs. */
1895 splittable_regs[regno]
1896 = GEN_INT (INTVAL (giv_inc)
1897 + INTVAL (splittable_regs[src_regno]));
1898 giv_inc = splittable_regs[regno];
1900 /* Now split the induction variable by changing the dest
1901 of this insn to a new register, and setting its
1902 reg_map entry to point to this new register.
1904 If this is the last iteration, and this is the last insn
1905 that will update the iv, then reuse the original dest,
1906 to ensure that the iv will have the proper value when
1907 the loop exits or repeats.
1909 Using splittable_regs_updates here like this is safe,
1910 because it can only be greater than one if all
1911 instructions modifying the iv are always executed in
1914 if (! last_iteration
1915 || (splittable_regs_updates[regno]-- != 1))
1917 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1919 map->reg_map[regno] = tem;
1920 record_base_value (REGNO (tem),
1921 giv_inc == const0_rtx
1923 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1924 giv_src_reg, giv_inc),
1928 map->reg_map[regno] = giv_src_reg;
1931 /* The constant being added could be too large for an add
1932 immediate, so can't directly emit an insn here. */
1933 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1934 copy = get_last_insn ();
1935 pattern = PATTERN (copy);
1939 pattern = copy_rtx_and_substitute (pattern, map);
1940 copy = emit_insn (pattern);
1942 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1945 /* If this insn is setting CC0, it may need to look at
1946 the insn that uses CC0 to see what type of insn it is.
1947 In that case, the call to recog via validate_change will
1948 fail. So don't substitute constants here. Instead,
1949 do it when we emit the following insn.
1951 For example, see the pyr.md file. That machine has signed and
1952 unsigned compares. The compare patterns must check the
1953 following branch insn to see which what kind of compare to
1956 If the previous insn set CC0, substitute constants on it as
1958 if (sets_cc0_p (PATTERN (copy)) != 0)
1963 try_constants (cc0_insn, map);
1965 try_constants (copy, map);
1968 try_constants (copy, map);
1971 /* Make split induction variable constants `permanent' since we
1972 know there are no backward branches across iteration variable
1973 settings which would invalidate this. */
1974 if (dest_reg_was_split)
1976 int regno = REGNO (SET_DEST (pattern));
1978 if (regno < VARRAY_SIZE (map->const_equiv_varray)
1979 && (VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age
1981 VARRAY_CONST_EQUIV (map->const_equiv_varray, regno).age = -1;
1986 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
1987 copy = emit_jump_insn (pattern);
1988 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1990 if (JUMP_LABEL (insn) == start_label && insn == copy_end
1991 && ! last_iteration)
1993 /* This is a branch to the beginning of the loop; this is the
1994 last insn being copied; and this is not the last iteration.
1995 In this case, we want to change the original fall through
1996 case to be a branch past the end of the loop, and the
1997 original jump label case to fall_through. */
1999 if (invert_exp (pattern, copy))
2001 if (! redirect_exp (&pattern,
2002 get_label_from_map (map,
2004 (JUMP_LABEL (insn))),
2011 rtx lab = gen_label_rtx ();
2012 /* Can't do it by reversing the jump (probably because we
2013 couldn't reverse the conditions), so emit a new
2014 jump_insn after COPY, and redirect the jump around
2016 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
2017 jmp = emit_barrier_after (jmp);
2018 emit_label_after (lab, jmp);
2019 LABEL_NUSES (lab) = 0;
2020 if (! redirect_exp (&pattern,
2021 get_label_from_map (map,
2023 (JUMP_LABEL (insn))),
2031 try_constants (cc0_insn, map);
2034 try_constants (copy, map);
2036 /* Set the jump label of COPY correctly to avoid problems with
2037 later passes of unroll_loop, if INSN had jump label set. */
2038 if (JUMP_LABEL (insn))
2042 /* Can't use the label_map for every insn, since this may be
2043 the backward branch, and hence the label was not mapped. */
2044 if ((set = single_set (copy)))
2046 tem = SET_SRC (set);
2047 if (GET_CODE (tem) == LABEL_REF)
2048 label = XEXP (tem, 0);
2049 else if (GET_CODE (tem) == IF_THEN_ELSE)
2051 if (XEXP (tem, 1) != pc_rtx)
2052 label = XEXP (XEXP (tem, 1), 0);
2054 label = XEXP (XEXP (tem, 2), 0);
2058 if (label && GET_CODE (label) == CODE_LABEL)
2059 JUMP_LABEL (copy) = label;
2062 /* An unrecognizable jump insn, probably the entry jump
2063 for a switch statement. This label must have been mapped,
2064 so just use the label_map to get the new jump label. */
2066 = get_label_from_map (map,
2067 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2070 /* If this is a non-local jump, then must increase the label
2071 use count so that the label will not be deleted when the
2072 original jump is deleted. */
2073 LABEL_NUSES (JUMP_LABEL (copy))++;
2075 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2076 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2078 rtx pat = PATTERN (copy);
2079 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2080 int len = XVECLEN (pat, diff_vec_p);
2083 for (i = 0; i < len; i++)
2084 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2087 /* If this used to be a conditional jump insn but whose branch
2088 direction is now known, we must do something special. */
2089 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2092 /* The previous insn set cc0 for us. So delete it. */
2093 delete_insn (PREV_INSN (copy));
2096 /* If this is now a no-op, delete it. */
2097 if (map->last_pc_value == pc_rtx)
2099 /* Don't let delete_insn delete the label referenced here,
2100 because we might possibly need it later for some other
2101 instruction in the loop. */
2102 if (JUMP_LABEL (copy))
2103 LABEL_NUSES (JUMP_LABEL (copy))++;
2105 if (JUMP_LABEL (copy))
2106 LABEL_NUSES (JUMP_LABEL (copy))--;
2110 /* Otherwise, this is unconditional jump so we must put a
2111 BARRIER after it. We could do some dead code elimination
2112 here, but jump.c will do it just as well. */
2118 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
2119 copy = emit_call_insn (pattern);
2120 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2122 /* Because the USAGE information potentially contains objects other
2123 than hard registers, we need to copy it. */
2124 CALL_INSN_FUNCTION_USAGE (copy)
2125 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn), map);
2129 try_constants (cc0_insn, map);
2132 try_constants (copy, map);
2134 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2135 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2136 VARRAY_CONST_EQUIV (map->const_equiv_varray, i).rtx = 0;
2140 /* If this is the loop start label, then we don't need to emit a
2141 copy of this label since no one will use it. */
2143 if (insn != start_label)
2145 copy = emit_label (get_label_from_map (map,
2146 CODE_LABEL_NUMBER (insn)));
2152 copy = emit_barrier ();
2156 /* VTOP and CONT notes are valid only before the loop exit test.
2157 If placed anywhere else, loop may generate bad code. */
2158 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2159 the associated rtl. We do not want to share the structure in
2162 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2163 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2164 && ((NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2165 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_CONT)
2166 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2167 copy = emit_note (NOTE_SOURCE_FILE (insn),
2168 NOTE_LINE_NUMBER (insn));
2178 map->insn_map[INSN_UID (insn)] = copy;
2180 while (insn != copy_end);
2182 /* Now finish coping the REG_NOTES. */
2186 insn = NEXT_INSN (insn);
2187 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2188 || GET_CODE (insn) == CALL_INSN)
2189 && map->insn_map[INSN_UID (insn)])
2190 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2192 while (insn != copy_end);
2194 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2195 each of these notes here, since there may be some important ones, such as
2196 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2197 iteration, because the original notes won't be deleted.
2199 We can't use insert_before here, because when from preconditioning,
2200 insert_before points before the loop. We can't use copy_end, because
2201 there may be insns already inserted after it (which we don't want to
2202 copy) when not from preconditioning code. */
2204 if (! last_iteration)
2206 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2208 /* VTOP notes are valid only before the loop exit test.
2209 If placed anywhere else, loop may generate bad code.
2210 There is no need to test for NOTE_INSN_LOOP_CONT notes
2211 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2212 instructions before the last insn in the loop, and if the
2213 end test is that short, there will be a VTOP note between
2214 the CONT note and the test. */
2215 if (GET_CODE (insn) == NOTE
2216 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2217 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK
2218 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP)
2219 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2223 if (final_label && LABEL_NUSES (final_label) > 0)
2224 emit_label (final_label);
2226 tem = gen_sequence ();
2228 emit_insn_before (tem, insert_before);
2231 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2232 emitted. This will correctly handle the case where the increment value
2233 won't fit in the immediate field of a PLUS insns. */
2236 emit_unrolled_add (dest_reg, src_reg, increment)
2237 rtx dest_reg, src_reg, increment;
2241 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2242 dest_reg, 0, OPTAB_LIB_WIDEN);
2244 if (dest_reg != result)
2245 emit_move_insn (dest_reg, result);
2248 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2249 is a backward branch in that range that branches to somewhere between
2250 LOOP_START and INSN. Returns 0 otherwise. */
2252 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2253 In practice, this is not a problem, because this function is seldom called,
2254 and uses a negligible amount of CPU time on average. */
2257 back_branch_in_range_p (insn, loop_start, loop_end)
2259 rtx loop_start, loop_end;
2261 rtx p, q, target_insn;
2262 rtx orig_loop_end = loop_end;
2264 /* Stop before we get to the backward branch at the end of the loop. */
2265 loop_end = prev_nonnote_insn (loop_end);
2266 if (GET_CODE (loop_end) == BARRIER)
2267 loop_end = PREV_INSN (loop_end);
2269 /* Check in case insn has been deleted, search forward for first non
2270 deleted insn following it. */
2271 while (INSN_DELETED_P (insn))
2272 insn = NEXT_INSN (insn);
2274 /* Check for the case where insn is the last insn in the loop. Deal
2275 with the case where INSN was a deleted loop test insn, in which case
2276 it will now be the NOTE_LOOP_END. */
2277 if (insn == loop_end || insn == orig_loop_end)
2280 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2282 if (GET_CODE (p) == JUMP_INSN)
2284 target_insn = JUMP_LABEL (p);
2286 /* Search from loop_start to insn, to see if one of them is
2287 the target_insn. We can't use INSN_LUID comparisons here,
2288 since insn may not have an LUID entry. */
2289 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2290 if (q == target_insn)
2298 /* Try to generate the simplest rtx for the expression
2299 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2303 fold_rtx_mult_add (mult1, mult2, add1, mode)
2304 rtx mult1, mult2, add1;
2305 enum machine_mode mode;
2310 /* The modes must all be the same. This should always be true. For now,
2311 check to make sure. */
2312 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2313 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2314 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2317 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2318 will be a constant. */
2319 if (GET_CODE (mult1) == CONST_INT)
2326 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2328 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2330 /* Again, put the constant second. */
2331 if (GET_CODE (add1) == CONST_INT)
2338 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2340 result = gen_rtx_PLUS (mode, add1, mult_res);
2345 /* Searches the list of induction struct's for the biv BL, to try to calculate
2346 the total increment value for one iteration of the loop as a constant.
2348 Returns the increment value as an rtx, simplified as much as possible,
2349 if it can be calculated. Otherwise, returns 0. */
2352 biv_total_increment (bl, loop_start, loop_end)
2353 struct iv_class *bl;
2354 rtx loop_start, loop_end;
2356 struct induction *v;
2359 /* For increment, must check every instruction that sets it. Each
2360 instruction must be executed only once each time through the loop.
2361 To verify this, we check that the insn is always executed, and that
2362 there are no backward branches after the insn that branch to before it.
2363 Also, the insn must have a mult_val of one (to make sure it really is
2366 result = const0_rtx;
2367 for (v = bl->biv; v; v = v->next_iv)
2369 if (v->always_computable && v->mult_val == const1_rtx
2370 && ! v->maybe_multiple)
2371 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2379 /* Determine the initial value of the iteration variable, and the amount
2380 that it is incremented each loop. Use the tables constructed by
2381 the strength reduction pass to calculate these values.
2383 Initial_value and/or increment are set to zero if their values could not
2387 iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
2388 rtx iteration_var, *initial_value, *increment;
2389 rtx loop_start, loop_end;
2391 struct iv_class *bl;
2393 struct induction *v;
2396 /* Clear the result values, in case no answer can be found. */
2400 /* The iteration variable can be either a giv or a biv. Check to see
2401 which it is, and compute the variable's initial value, and increment
2402 value if possible. */
2404 /* If this is a new register, can't handle it since we don't have any
2405 reg_iv_type entry for it. */
2406 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements)
2408 if (loop_dump_stream)
2409 fprintf (loop_dump_stream,
2410 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2414 /* Reject iteration variables larger than the host wide int size, since they
2415 could result in a number of iterations greater than the range of our
2416 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2417 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2418 > HOST_BITS_PER_WIDE_INT))
2420 if (loop_dump_stream)
2421 fprintf (loop_dump_stream,
2422 "Loop unrolling: Iteration var rejected because mode too large.\n");
2425 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2427 if (loop_dump_stream)
2428 fprintf (loop_dump_stream,
2429 "Loop unrolling: Iteration var not an integer.\n");
2432 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2434 /* When reg_iv_type / reg_iv_info is resized for biv increments
2435 that are turned into givs, reg_biv_class is not resized.
2436 So check here that we don't make an out-of-bounds access. */
2437 if (REGNO (iteration_var) >= max_reg_before_loop)
2440 /* Grab initial value, only useful if it is a constant. */
2441 bl = reg_biv_class[REGNO (iteration_var)];
2442 *initial_value = bl->initial_value;
2444 *increment = biv_total_increment (bl, loop_start, loop_end);
2446 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2448 HOST_WIDE_INT offset = 0;
2449 struct induction *v = REG_IV_INFO (REGNO (iteration_var));
2451 if (REGNO (v->src_reg) >= max_reg_before_loop)
2454 bl = reg_biv_class[REGNO (v->src_reg)];
2456 /* Increment value is mult_val times the increment value of the biv. */
2458 *increment = biv_total_increment (bl, loop_start, loop_end);
2461 struct induction *biv_inc;
2464 = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx, v->mode);
2465 /* The caller assumes that one full increment has occured at the
2466 first loop test. But that's not true when the biv is incremented
2467 after the giv is set (which is the usual case), e.g.:
2468 i = 6; do {;} while (i++ < 9) .
2469 Therefore, we bias the initial value by subtracting the amount of
2470 the increment that occurs between the giv set and the giv test. */
2471 for (biv_inc = bl->biv; biv_inc; biv_inc = biv_inc->next_iv)
2473 if (loop_insn_first_p (v->insn, biv_inc->insn))
2474 offset -= INTVAL (biv_inc->add_val);
2476 offset *= INTVAL (v->mult_val);
2478 if (loop_dump_stream)
2479 fprintf (loop_dump_stream,
2480 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2482 /* Initial value is mult_val times the biv's initial value plus
2483 add_val. Only useful if it is a constant. */
2485 = fold_rtx_mult_add (v->mult_val,
2486 plus_constant (bl->initial_value, offset),
2487 v->add_val, v->mode);
2491 if (loop_dump_stream)
2492 fprintf (loop_dump_stream,
2493 "Loop unrolling: Not basic or general induction var.\n");
2499 /* For each biv and giv, determine whether it can be safely split into
2500 a different variable for each unrolled copy of the loop body. If it
2501 is safe to split, then indicate that by saving some useful info
2502 in the splittable_regs array.
2504 If the loop is being completely unrolled, then splittable_regs will hold
2505 the current value of the induction variable while the loop is unrolled.
2506 It must be set to the initial value of the induction variable here.
2507 Otherwise, splittable_regs will hold the difference between the current
2508 value of the induction variable and the value the induction variable had
2509 at the top of the loop. It must be set to the value 0 here.
2511 Returns the total number of instructions that set registers that are
2514 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2515 constant values are unnecessary, since we can easily calculate increment
2516 values in this case even if nothing is constant. The increment value
2517 should not involve a multiply however. */
2519 /* ?? Even if the biv/giv increment values aren't constant, it may still
2520 be beneficial to split the variable if the loop is only unrolled a few
2521 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2524 find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
2525 unroll_number, n_iterations)
2526 enum unroll_types unroll_type;
2527 rtx loop_start, loop_end;
2528 rtx end_insert_before;
2530 unsigned HOST_WIDE_INT n_iterations;
2532 struct iv_class *bl;
2533 struct induction *v;
2535 rtx biv_final_value;
2539 for (bl = loop_iv_list; bl; bl = bl->next)
2541 /* Biv_total_increment must return a constant value,
2542 otherwise we can not calculate the split values. */
2544 increment = biv_total_increment (bl, loop_start, loop_end);
2545 if (! increment || GET_CODE (increment) != CONST_INT)
2548 /* The loop must be unrolled completely, or else have a known number
2549 of iterations and only one exit, or else the biv must be dead
2550 outside the loop, or else the final value must be known. Otherwise,
2551 it is unsafe to split the biv since it may not have the proper
2552 value on loop exit. */
2554 /* loop_number_exit_count is non-zero if the loop has an exit other than
2555 a fall through at the end. */
2558 biv_final_value = 0;
2559 if (unroll_type != UNROLL_COMPLETELY
2560 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2561 || unroll_type == UNROLL_NAIVE)
2562 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2564 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2565 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2566 < INSN_LUID (bl->init_insn))
2567 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2568 && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end,
2572 /* If any of the insns setting the BIV don't do so with a simple
2573 PLUS, we don't know how to split it. */
2574 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2575 if ((tem = single_set (v->insn)) == 0
2576 || GET_CODE (SET_DEST (tem)) != REG
2577 || REGNO (SET_DEST (tem)) != bl->regno
2578 || GET_CODE (SET_SRC (tem)) != PLUS)
2581 /* If final value is non-zero, then must emit an instruction which sets
2582 the value of the biv to the proper value. This is done after
2583 handling all of the givs, since some of them may need to use the
2584 biv's value in their initialization code. */
2586 /* This biv is splittable. If completely unrolling the loop, save
2587 the biv's initial value. Otherwise, save the constant zero. */
2589 if (biv_splittable == 1)
2591 if (unroll_type == UNROLL_COMPLETELY)
2593 /* If the initial value of the biv is itself (i.e. it is too
2594 complicated for strength_reduce to compute), or is a hard
2595 register, or it isn't invariant, then we must create a new
2596 pseudo reg to hold the initial value of the biv. */
2598 if (GET_CODE (bl->initial_value) == REG
2599 && (REGNO (bl->initial_value) == bl->regno
2600 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2601 || ! invariant_p (bl->initial_value)))
2603 rtx tem = gen_reg_rtx (bl->biv->mode);
2605 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2606 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2609 if (loop_dump_stream)
2610 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2611 bl->regno, REGNO (tem));
2613 splittable_regs[bl->regno] = tem;
2616 splittable_regs[bl->regno] = bl->initial_value;
2619 splittable_regs[bl->regno] = const0_rtx;
2621 /* Save the number of instructions that modify the biv, so that
2622 we can treat the last one specially. */
2624 splittable_regs_updates[bl->regno] = bl->biv_count;
2625 result += bl->biv_count;
2627 if (loop_dump_stream)
2628 fprintf (loop_dump_stream,
2629 "Biv %d safe to split.\n", bl->regno);
2632 /* Check every giv that depends on this biv to see whether it is
2633 splittable also. Even if the biv isn't splittable, givs which
2634 depend on it may be splittable if the biv is live outside the
2635 loop, and the givs aren't. */
2637 result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
2638 increment, unroll_number);
2640 /* If final value is non-zero, then must emit an instruction which sets
2641 the value of the biv to the proper value. This is done after
2642 handling all of the givs, since some of them may need to use the
2643 biv's value in their initialization code. */
2644 if (biv_final_value)
2646 /* If the loop has multiple exits, emit the insns before the
2647 loop to ensure that it will always be executed no matter
2648 how the loop exits. Otherwise emit the insn after the loop,
2649 since this is slightly more efficient. */
2650 if (! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
2651 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2656 /* Create a new register to hold the value of the biv, and then
2657 set the biv to its final value before the loop start. The biv
2658 is set to its final value before loop start to ensure that
2659 this insn will always be executed, no matter how the loop
2661 rtx tem = gen_reg_rtx (bl->biv->mode);
2662 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2664 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2666 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2670 if (loop_dump_stream)
2671 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2672 REGNO (bl->biv->src_reg), REGNO (tem));
2674 /* Set up the mapping from the original biv register to the new
2676 bl->biv->src_reg = tem;
2683 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2684 for the instruction that is using it. Do not make any changes to that
2688 verify_addresses (v, giv_inc, unroll_number)
2689 struct induction *v;
2694 rtx orig_addr = *v->location;
2695 rtx last_addr = plus_constant (v->dest_reg,
2696 INTVAL (giv_inc) * (unroll_number - 1));
2698 /* First check to see if either address would fail. Handle the fact
2699 that we have may have a match_dup. */
2700 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2701 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2704 /* Now put things back the way they were before. This should always
2706 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2712 /* For every giv based on the biv BL, check to determine whether it is
2713 splittable. This is a subroutine to find_splittable_regs ().
2715 Return the number of instructions that set splittable registers. */
2718 find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
2720 struct iv_class *bl;
2721 enum unroll_types unroll_type;
2722 rtx loop_start, loop_end;
2726 struct induction *v, *v2;
2731 /* Scan the list of givs, and set the same_insn field when there are
2732 multiple identical givs in the same insn. */
2733 for (v = bl->giv; v; v = v->next_iv)
2734 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2735 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2739 for (v = bl->giv; v; v = v->next_iv)
2743 /* Only split the giv if it has already been reduced, or if the loop is
2744 being completely unrolled. */
2745 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2748 /* The giv can be split if the insn that sets the giv is executed once
2749 and only once on every iteration of the loop. */
2750 /* An address giv can always be split. v->insn is just a use not a set,
2751 and hence it does not matter whether it is always executed. All that
2752 matters is that all the biv increments are always executed, and we
2753 won't reach here if they aren't. */
2754 if (v->giv_type != DEST_ADDR
2755 && (! v->always_computable
2756 || back_branch_in_range_p (v->insn, loop_start, loop_end)))
2759 /* The giv increment value must be a constant. */
2760 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2762 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2765 /* The loop must be unrolled completely, or else have a known number of
2766 iterations and only one exit, or else the giv must be dead outside
2767 the loop, or else the final value of the giv must be known.
2768 Otherwise, it is not safe to split the giv since it may not have the
2769 proper value on loop exit. */
2771 /* The used outside loop test will fail for DEST_ADDR givs. They are
2772 never used outside the loop anyways, so it is always safe to split a
2776 if (unroll_type != UNROLL_COMPLETELY
2777 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2778 || unroll_type == UNROLL_NAIVE)
2779 && v->giv_type != DEST_ADDR
2780 /* The next part is true if the pseudo is used outside the loop.
2781 We assume that this is true for any pseudo created after loop
2782 starts, because we don't have a reg_n_info entry for them. */
2783 && (REGNO (v->dest_reg) >= max_reg_before_loop
2784 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2785 /* Check for the case where the pseudo is set by a shift/add
2786 sequence, in which case the first insn setting the pseudo
2787 is the first insn of the shift/add sequence. */
2788 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2789 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2790 != INSN_UID (XEXP (tem, 0)))))
2791 /* Line above always fails if INSN was moved by loop opt. */
2792 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2793 >= INSN_LUID (loop_end)))
2794 /* Givs made from biv increments are missed by the above test, so
2795 test explicitly for them. */
2796 && (REGNO (v->dest_reg) < first_increment_giv
2797 || REGNO (v->dest_reg) > last_increment_giv)
2798 && ! (final_value = v->final_value))
2802 /* Currently, non-reduced/final-value givs are never split. */
2803 /* Should emit insns after the loop if possible, as the biv final value
2806 /* If the final value is non-zero, and the giv has not been reduced,
2807 then must emit an instruction to set the final value. */
2808 if (final_value && !v->new_reg)
2810 /* Create a new register to hold the value of the giv, and then set
2811 the giv to its final value before the loop start. The giv is set
2812 to its final value before loop start to ensure that this insn
2813 will always be executed, no matter how we exit. */
2814 tem = gen_reg_rtx (v->mode);
2815 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2816 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2819 if (loop_dump_stream)
2820 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2821 REGNO (v->dest_reg), REGNO (tem));
2827 /* This giv is splittable. If completely unrolling the loop, save the
2828 giv's initial value. Otherwise, save the constant zero for it. */
2830 if (unroll_type == UNROLL_COMPLETELY)
2832 /* It is not safe to use bl->initial_value here, because it may not
2833 be invariant. It is safe to use the initial value stored in
2834 the splittable_regs array if it is set. In rare cases, it won't
2835 be set, so then we do exactly the same thing as
2836 find_splittable_regs does to get a safe value. */
2837 rtx biv_initial_value;
2839 if (splittable_regs[bl->regno])
2840 biv_initial_value = splittable_regs[bl->regno];
2841 else if (GET_CODE (bl->initial_value) != REG
2842 || (REGNO (bl->initial_value) != bl->regno
2843 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2844 biv_initial_value = bl->initial_value;
2847 rtx tem = gen_reg_rtx (bl->biv->mode);
2849 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2850 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2852 biv_initial_value = tem;
2854 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2855 v->add_val, v->mode);
2862 /* If a giv was combined with another giv, then we can only split
2863 this giv if the giv it was combined with was reduced. This
2864 is because the value of v->new_reg is meaningless in this
2866 if (v->same && ! v->same->new_reg)
2868 if (loop_dump_stream)
2869 fprintf (loop_dump_stream,
2870 "giv combined with unreduced giv not split.\n");
2873 /* If the giv is an address destination, it could be something other
2874 than a simple register, these have to be treated differently. */
2875 else if (v->giv_type == DEST_REG)
2877 /* If value is not a constant, register, or register plus
2878 constant, then compute its value into a register before
2879 loop start. This prevents invalid rtx sharing, and should
2880 generate better code. We can use bl->initial_value here
2881 instead of splittable_regs[bl->regno] because this code
2882 is going before the loop start. */
2883 if (unroll_type == UNROLL_COMPLETELY
2884 && GET_CODE (value) != CONST_INT
2885 && GET_CODE (value) != REG
2886 && (GET_CODE (value) != PLUS
2887 || GET_CODE (XEXP (value, 0)) != REG
2888 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2890 rtx tem = gen_reg_rtx (v->mode);
2891 record_base_value (REGNO (tem), v->add_val, 0);
2892 emit_iv_add_mult (bl->initial_value, v->mult_val,
2893 v->add_val, tem, loop_start);
2897 splittable_regs[REGNO (v->new_reg)] = value;
2898 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
2902 /* Splitting address givs is useful since it will often allow us
2903 to eliminate some increment insns for the base giv as
2906 /* If the addr giv is combined with a dest_reg giv, then all
2907 references to that dest reg will be remapped, which is NOT
2908 what we want for split addr regs. We always create a new
2909 register for the split addr giv, just to be safe. */
2911 /* If we have multiple identical address givs within a
2912 single instruction, then use a single pseudo reg for
2913 both. This is necessary in case one is a match_dup
2916 v->const_adjust = 0;
2920 v->dest_reg = v->same_insn->dest_reg;
2921 if (loop_dump_stream)
2922 fprintf (loop_dump_stream,
2923 "Sharing address givs in insn %d\n",
2924 INSN_UID (v->insn));
2926 /* If multiple address GIVs have been combined with the
2927 same dest_reg GIV, do not create a new register for
2929 else if (unroll_type != UNROLL_COMPLETELY
2930 && v->giv_type == DEST_ADDR
2931 && v->same && v->same->giv_type == DEST_ADDR
2932 && v->same->unrolled
2933 /* combine_givs_p may return true for some cases
2934 where the add and mult values are not equal.
2935 To share a register here, the values must be
2937 && rtx_equal_p (v->same->mult_val, v->mult_val)
2938 && rtx_equal_p (v->same->add_val, v->add_val)
2939 /* If the memory references have different modes,
2940 then the address may not be valid and we must
2941 not share registers. */
2942 && verify_addresses (v, giv_inc, unroll_number))
2944 v->dest_reg = v->same->dest_reg;
2947 else if (unroll_type != UNROLL_COMPLETELY)
2949 /* If not completely unrolling the loop, then create a new
2950 register to hold the split value of the DEST_ADDR giv.
2951 Emit insn to initialize its value before loop start. */
2953 rtx tem = gen_reg_rtx (v->mode);
2954 struct induction *same = v->same;
2955 rtx new_reg = v->new_reg;
2956 record_base_value (REGNO (tem), v->add_val, 0);
2958 if (same && same->derived_from)
2960 /* calculate_giv_inc doesn't work for derived givs.
2961 copy_loop_body works around the problem for the
2962 DEST_REG givs themselves, but it can't handle
2963 DEST_ADDR givs that have been combined with
2964 a derived DEST_REG giv.
2965 So Handle V as if the giv from which V->SAME has
2966 been derived has been combined with V.
2967 recombine_givs only derives givs from givs that
2968 are reduced the ordinary, so we need not worry
2969 about same->derived_from being in turn derived. */
2971 same = same->derived_from;
2972 new_reg = express_from (same, v);
2973 new_reg = replace_rtx (new_reg, same->dest_reg,
2977 /* If the address giv has a constant in its new_reg value,
2978 then this constant can be pulled out and put in value,
2979 instead of being part of the initialization code. */
2981 if (GET_CODE (new_reg) == PLUS
2982 && GET_CODE (XEXP (new_reg, 1)) == CONST_INT)
2985 = plus_constant (tem, INTVAL (XEXP (new_reg, 1)));
2987 /* Only succeed if this will give valid addresses.
2988 Try to validate both the first and the last
2989 address resulting from loop unrolling, if
2990 one fails, then can't do const elim here. */
2991 if (verify_addresses (v, giv_inc, unroll_number))
2993 /* Save the negative of the eliminated const, so
2994 that we can calculate the dest_reg's increment
2996 v->const_adjust = - INTVAL (XEXP (new_reg, 1));
2998 new_reg = XEXP (new_reg, 0);
2999 if (loop_dump_stream)
3000 fprintf (loop_dump_stream,
3001 "Eliminating constant from giv %d\n",
3010 /* If the address hasn't been checked for validity yet, do so
3011 now, and fail completely if either the first or the last
3012 unrolled copy of the address is not a valid address
3013 for the instruction that uses it. */
3014 if (v->dest_reg == tem
3015 && ! verify_addresses (v, giv_inc, unroll_number))
3017 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3018 if (v2->same_insn == v)
3021 if (loop_dump_stream)
3022 fprintf (loop_dump_stream,
3023 "Invalid address for giv at insn %d\n",
3024 INSN_UID (v->insn));
3028 v->new_reg = new_reg;
3031 /* We set this after the address check, to guarantee that
3032 the register will be initialized. */
3035 /* To initialize the new register, just move the value of
3036 new_reg into it. This is not guaranteed to give a valid
3037 instruction on machines with complex addressing modes.
3038 If we can't recognize it, then delete it and emit insns
3039 to calculate the value from scratch. */
3040 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
3041 copy_rtx (v->new_reg)),
3043 if (recog_memoized (PREV_INSN (loop_start)) < 0)
3047 /* We can't use bl->initial_value to compute the initial
3048 value, because the loop may have been preconditioned.
3049 We must calculate it from NEW_REG. Try using
3050 force_operand instead of emit_iv_add_mult. */
3051 delete_insn (PREV_INSN (loop_start));
3054 ret = force_operand (v->new_reg, tem);
3056 emit_move_insn (tem, ret);
3057 sequence = gen_sequence ();
3059 emit_insn_before (sequence, loop_start);
3061 if (loop_dump_stream)
3062 fprintf (loop_dump_stream,
3063 "Invalid init insn, rewritten.\n");
3068 v->dest_reg = value;
3070 /* Check the resulting address for validity, and fail
3071 if the resulting address would be invalid. */
3072 if (! verify_addresses (v, giv_inc, unroll_number))
3074 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3075 if (v2->same_insn == v)
3078 if (loop_dump_stream)
3079 fprintf (loop_dump_stream,
3080 "Invalid address for giv at insn %d\n",
3081 INSN_UID (v->insn));
3084 if (v->same && v->same->derived_from)
3086 /* Handle V as if the giv from which V->SAME has
3087 been derived has been combined with V. */
3089 v->same = v->same->derived_from;
3090 v->new_reg = express_from (v->same, v);
3091 v->new_reg = replace_rtx (v->new_reg, v->same->dest_reg,
3097 /* Store the value of dest_reg into the insn. This sharing
3098 will not be a problem as this insn will always be copied
3101 *v->location = v->dest_reg;
3103 /* If this address giv is combined with a dest reg giv, then
3104 save the base giv's induction pointer so that we will be
3105 able to handle this address giv properly. The base giv
3106 itself does not have to be splittable. */
3108 if (v->same && v->same->giv_type == DEST_REG)
3109 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3111 if (GET_CODE (v->new_reg) == REG)
3113 /* This giv maybe hasn't been combined with any others.
3114 Make sure that it's giv is marked as splittable here. */
3116 splittable_regs[REGNO (v->new_reg)] = value;
3117 derived_regs[REGNO (v->new_reg)] = v->derived_from != 0;
3119 /* Make it appear to depend upon itself, so that the
3120 giv will be properly split in the main loop above. */
3124 addr_combined_regs[REGNO (v->new_reg)] = v;
3128 if (loop_dump_stream)
3129 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3135 /* Currently, unreduced giv's can't be split. This is not too much
3136 of a problem since unreduced giv's are not live across loop
3137 iterations anyways. When unrolling a loop completely though,
3138 it makes sense to reduce&split givs when possible, as this will
3139 result in simpler instructions, and will not require that a reg
3140 be live across loop iterations. */
3142 splittable_regs[REGNO (v->dest_reg)] = value;
3143 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3144 REGNO (v->dest_reg), INSN_UID (v->insn));
3150 /* Unreduced givs are only updated once by definition. Reduced givs
3151 are updated as many times as their biv is. Mark it so if this is
3152 a splittable register. Don't need to do anything for address givs
3153 where this may not be a register. */
3155 if (GET_CODE (v->new_reg) == REG)
3159 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3161 if (count > 1 && v->derived_from)
3162 /* In this case, there is one set where the giv insn was and one
3163 set each after each biv increment. (Most are likely dead.) */
3166 splittable_regs_updates[REGNO (v->new_reg)] = count;
3171 if (loop_dump_stream)
3175 if (GET_CODE (v->dest_reg) == CONST_INT)
3177 else if (GET_CODE (v->dest_reg) != REG)
3178 regnum = REGNO (XEXP (v->dest_reg, 0));
3180 regnum = REGNO (v->dest_reg);
3181 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3182 regnum, INSN_UID (v->insn));
3189 /* Try to prove that the register is dead after the loop exits. Trace every
3190 loop exit looking for an insn that will always be executed, which sets
3191 the register to some value, and appears before the first use of the register
3192 is found. If successful, then return 1, otherwise return 0. */
3194 /* ?? Could be made more intelligent in the handling of jumps, so that
3195 it can search past if statements and other similar structures. */
3198 reg_dead_after_loop (reg, loop_start, loop_end)
3199 rtx reg, loop_start, loop_end;
3204 int label_count = 0;
3205 int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
3207 /* In addition to checking all exits of this loop, we must also check
3208 all exits of inner nested loops that would exit this loop. We don't
3209 have any way to identify those, so we just give up if there are any
3210 such inner loop exits. */
3212 for (label = loop_number_exit_labels[this_loop_num]; label;
3213 label = LABEL_NEXTREF (label))
3216 if (label_count != loop_number_exit_count[this_loop_num])
3219 /* HACK: Must also search the loop fall through exit, create a label_ref
3220 here which points to the loop_end, and append the loop_number_exit_labels
3222 label = gen_rtx_LABEL_REF (VOIDmode, loop_end);
3223 LABEL_NEXTREF (label) = loop_number_exit_labels[this_loop_num];
3225 for ( ; label; label = LABEL_NEXTREF (label))
3227 /* Succeed if find an insn which sets the biv or if reach end of
3228 function. Fail if find an insn that uses the biv, or if come to
3229 a conditional jump. */
3231 insn = NEXT_INSN (XEXP (label, 0));
3234 code = GET_CODE (insn);
3235 if (GET_RTX_CLASS (code) == 'i')
3239 if (reg_referenced_p (reg, PATTERN (insn)))
3242 set = single_set (insn);
3243 if (set && rtx_equal_p (SET_DEST (set), reg))
3247 if (code == JUMP_INSN)
3249 if (GET_CODE (PATTERN (insn)) == RETURN)
3251 else if (! simplejump_p (insn)
3252 /* Prevent infinite loop following infinite loops. */
3253 || jump_count++ > 20)
3256 insn = JUMP_LABEL (insn);
3259 insn = NEXT_INSN (insn);
3263 /* Success, the register is dead on all loop exits. */
3267 /* Try to calculate the final value of the biv, the value it will have at
3268 the end of the loop. If we can do it, return that value. */
3271 final_biv_value (bl, loop_start, loop_end, n_iterations)
3272 struct iv_class *bl;
3273 rtx loop_start, loop_end;
3274 unsigned HOST_WIDE_INT n_iterations;
3278 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3280 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3283 /* The final value for reversed bivs must be calculated differently than
3284 for ordinary bivs. In this case, there is already an insn after the
3285 loop which sets this biv's final value (if necessary), and there are
3286 no other loop exits, so we can return any value. */
3289 if (loop_dump_stream)
3290 fprintf (loop_dump_stream,
3291 "Final biv value for %d, reversed biv.\n", bl->regno);
3296 /* Try to calculate the final value as initial value + (number of iterations
3297 * increment). For this to work, increment must be invariant, the only
3298 exit from the loop must be the fall through at the bottom (otherwise
3299 it may not have its final value when the loop exits), and the initial
3300 value of the biv must be invariant. */
3302 if (n_iterations != 0
3303 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
3304 && invariant_p (bl->initial_value))
3306 increment = biv_total_increment (bl, loop_start, loop_end);
3308 if (increment && invariant_p (increment))
3310 /* Can calculate the loop exit value, emit insns after loop
3311 end to calculate this value into a temporary register in
3312 case it is needed later. */
3314 tem = gen_reg_rtx (bl->biv->mode);
3315 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3316 /* Make sure loop_end is not the last insn. */
3317 if (NEXT_INSN (loop_end) == 0)
3318 emit_note_after (NOTE_INSN_DELETED, loop_end);
3319 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3320 bl->initial_value, tem, NEXT_INSN (loop_end));
3322 if (loop_dump_stream)
3323 fprintf (loop_dump_stream,
3324 "Final biv value for %d, calculated.\n", bl->regno);
3330 /* Check to see if the biv is dead at all loop exits. */
3331 if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
3333 if (loop_dump_stream)
3334 fprintf (loop_dump_stream,
3335 "Final biv value for %d, biv dead after loop exit.\n",
3344 /* Try to calculate the final value of the giv, the value it will have at
3345 the end of the loop. If we can do it, return that value. */
3348 final_giv_value (v, loop_start, loop_end, n_iterations)
3349 struct induction *v;
3350 rtx loop_start, loop_end;
3351 unsigned HOST_WIDE_INT n_iterations;
3353 struct iv_class *bl;
3356 rtx insert_before, seq;
3358 bl = reg_biv_class[REGNO (v->src_reg)];
3360 /* The final value for givs which depend on reversed bivs must be calculated
3361 differently than for ordinary givs. In this case, there is already an
3362 insn after the loop which sets this giv's final value (if necessary),
3363 and there are no other loop exits, so we can return any value. */
3366 if (loop_dump_stream)
3367 fprintf (loop_dump_stream,
3368 "Final giv value for %d, depends on reversed biv\n",
3369 REGNO (v->dest_reg));
3373 /* Try to calculate the final value as a function of the biv it depends
3374 upon. The only exit from the loop must be the fall through at the bottom
3375 (otherwise it may not have its final value when the loop exits). */
3377 /* ??? Can calculate the final giv value by subtracting off the
3378 extra biv increments times the giv's mult_val. The loop must have
3379 only one exit for this to work, but the loop iterations does not need
3382 if (n_iterations != 0
3383 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
3385 /* ?? It is tempting to use the biv's value here since these insns will
3386 be put after the loop, and hence the biv will have its final value
3387 then. However, this fails if the biv is subsequently eliminated.
3388 Perhaps determine whether biv's are eliminable before trying to
3389 determine whether giv's are replaceable so that we can use the
3390 biv value here if it is not eliminable. */
3392 /* We are emitting code after the end of the loop, so we must make
3393 sure that bl->initial_value is still valid then. It will still
3394 be valid if it is invariant. */
3396 increment = biv_total_increment (bl, loop_start, loop_end);
3398 if (increment && invariant_p (increment)
3399 && invariant_p (bl->initial_value))
3401 /* Can calculate the loop exit value of its biv as
3402 (n_iterations * increment) + initial_value */
3404 /* The loop exit value of the giv is then
3405 (final_biv_value - extra increments) * mult_val + add_val.
3406 The extra increments are any increments to the biv which
3407 occur in the loop after the giv's value is calculated.
3408 We must search from the insn that sets the giv to the end
3409 of the loop to calculate this value. */
3411 insert_before = NEXT_INSN (loop_end);
3413 /* Put the final biv value in tem. */
3414 tem = gen_reg_rtx (bl->biv->mode);
3415 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3416 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3417 bl->initial_value, tem, insert_before);
3419 /* Subtract off extra increments as we find them. */
3420 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3421 insn = NEXT_INSN (insn))
3423 struct induction *biv;
3425 for (biv = bl->biv; biv; biv = biv->next_iv)
3426 if (biv->insn == insn)
3429 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3430 biv->add_val, NULL_RTX, 0,
3432 seq = gen_sequence ();
3434 emit_insn_before (seq, insert_before);
3438 /* Now calculate the giv's final value. */
3439 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3442 if (loop_dump_stream)
3443 fprintf (loop_dump_stream,
3444 "Final giv value for %d, calc from biv's value.\n",
3445 REGNO (v->dest_reg));
3451 /* Replaceable giv's should never reach here. */
3455 /* Check to see if the biv is dead at all loop exits. */
3456 if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
3458 if (loop_dump_stream)
3459 fprintf (loop_dump_stream,
3460 "Final giv value for %d, giv dead after loop exit.\n",
3461 REGNO (v->dest_reg));
3470 /* Look back before LOOP_START for then insn that sets REG and return
3471 the equivalent constant if there is a REG_EQUAL note otherwise just
3472 the SET_SRC of REG. */
3475 loop_find_equiv_value (loop_start, reg)
3483 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3485 if (GET_CODE (insn) == CODE_LABEL)
3488 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3489 && reg_set_p (reg, insn))
3491 /* We found the last insn before the loop that sets the register.
3492 If it sets the entire register, and has a REG_EQUAL note,
3493 then use the value of the REG_EQUAL note. */
3494 if ((set = single_set (insn))
3495 && (SET_DEST (set) == reg))
3497 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3499 /* Only use the REG_EQUAL note if it is a constant.
3500 Other things, divide in particular, will cause
3501 problems later if we use them. */
3502 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3503 && CONSTANT_P (XEXP (note, 0)))
3504 ret = XEXP (note, 0);
3506 ret = SET_SRC (set);
3515 /* Return a simplified rtx for the expression OP - REG.
3517 REG must appear in OP, and OP must be a register or the sum of a register
3520 Thus, the return value must be const0_rtx or the second term.
3522 The caller is responsible for verifying that REG appears in OP and OP has
3526 subtract_reg_term (op, reg)
3531 if (GET_CODE (op) == PLUS)
3533 if (XEXP (op, 0) == reg)
3534 return XEXP (op, 1);
3535 else if (XEXP (op, 1) == reg)
3536 return XEXP (op, 0);
3538 /* OP does not contain REG as a term. */
3543 /* Find and return register term common to both expressions OP0 and
3544 OP1 or NULL_RTX if no such term exists. Each expression must be a
3545 REG or a PLUS of a REG. */
3548 find_common_reg_term (op0, op1)
3551 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3552 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3559 if (GET_CODE (op0) == PLUS)
3560 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3562 op01 = const0_rtx, op00 = op0;
3564 if (GET_CODE (op1) == PLUS)
3565 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3567 op11 = const0_rtx, op10 = op1;
3569 /* Find and return common register term if present. */
3570 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3572 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3576 /* No common register term found. */
3581 /* Calculate the number of loop iterations. Returns the exact number of loop
3582 iterations if it can be calculated, otherwise returns zero. */
3584 unsigned HOST_WIDE_INT
3585 loop_iterations (loop_start, loop_end, loop_info)
3586 rtx loop_start, loop_end;
3587 struct loop_info *loop_info;
3589 rtx comparison, comparison_value;
3590 rtx iteration_var, initial_value, increment, final_value;
3591 enum rtx_code comparison_code;
3592 HOST_WIDE_INT abs_inc;
3593 unsigned HOST_WIDE_INT abs_diff;
3596 int unsigned_p, compare_dir, final_larger;
3601 loop_info->n_iterations = 0;
3602 loop_info->initial_value = 0;
3603 loop_info->initial_equiv_value = 0;
3604 loop_info->comparison_value = 0;
3605 loop_info->final_value = 0;
3606 loop_info->final_equiv_value = 0;
3607 loop_info->increment = 0;
3608 loop_info->iteration_var = 0;
3609 loop_info->unroll_number = 1;
3610 loop_info->vtop = 0;
3612 /* We used to use prev_nonnote_insn here, but that fails because it might
3613 accidentally get the branch for a contained loop if the branch for this
3614 loop was deleted. We can only trust branches immediately before the
3616 last_loop_insn = PREV_INSN (loop_end);
3618 /* ??? We should probably try harder to find the jump insn
3619 at the end of the loop. The following code assumes that
3620 the last loop insn is a jump to the top of the loop. */
3621 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3623 if (loop_dump_stream)
3624 fprintf (loop_dump_stream,
3625 "Loop iterations: No final conditional branch found.\n");
3629 /* If there is a more than a single jump to the top of the loop
3630 we cannot (easily) determine the iteration count. */
3631 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3633 if (loop_dump_stream)
3634 fprintf (loop_dump_stream,
3635 "Loop iterations: Loop has multiple back edges.\n");
3639 /* Find the iteration variable. If the last insn is a conditional
3640 branch, and the insn before tests a register value, make that the
3641 iteration variable. */
3643 comparison = get_condition_for_loop (last_loop_insn);
3644 if (comparison == 0)
3646 if (loop_dump_stream)
3647 fprintf (loop_dump_stream,
3648 "Loop iterations: No final comparison found.\n");
3652 /* ??? Get_condition may switch position of induction variable and
3653 invariant register when it canonicalizes the comparison. */
3655 comparison_code = GET_CODE (comparison);
3656 iteration_var = XEXP (comparison, 0);
3657 comparison_value = XEXP (comparison, 1);
3659 /* Check if there is a NOTE_INSN_LOOP_VTOP note. If there is,
3660 that means that this is a for or while style loop, with
3661 a loop exit test at the start. Thus, we can assume that
3662 the loop condition was true when the loop was entered.
3664 We start at the end and search backwards for the previous
3665 NOTE. If there is no NOTE_INSN_LOOP_VTOP for this loop,
3666 the search will stop at the NOTE_INSN_LOOP_CONT. */
3669 vtop = PREV_INSN (vtop);
3670 while (GET_CODE (vtop) != NOTE
3671 || NOTE_LINE_NUMBER (vtop) > 0
3672 || NOTE_LINE_NUMBER (vtop) == NOTE_REPEATED_LINE_NUMBER
3673 || NOTE_LINE_NUMBER (vtop) == NOTE_INSN_DELETED);
3674 if (NOTE_LINE_NUMBER (vtop) != NOTE_INSN_LOOP_VTOP)
3676 loop_info->vtop = vtop;
3678 if (GET_CODE (iteration_var) != REG)
3680 if (loop_dump_stream)
3681 fprintf (loop_dump_stream,
3682 "Loop iterations: Comparison not against register.\n");
3686 /* The only new registers that are created before loop iterations
3687 are givs made from biv increments or registers created by
3688 load_mems. In the latter case, it is possible that try_copy_prop
3689 will propagate a new pseudo into the old iteration register but
3690 this will be marked by having the REG_USERVAR_P bit set. */
3692 if ((unsigned) REGNO (iteration_var) >= reg_iv_type->num_elements
3693 && ! REG_USERVAR_P (iteration_var))
3696 iteration_info (iteration_var, &initial_value, &increment,
3697 loop_start, loop_end);
3698 if (initial_value == 0)
3699 /* iteration_info already printed a message. */
3704 switch (comparison_code)
3719 /* Cannot determine loop iterations with this case. */
3738 /* If the comparison value is an invariant register, then try to find
3739 its value from the insns before the start of the loop. */
3741 final_value = comparison_value;
3742 if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
3744 final_value = loop_find_equiv_value (loop_start, comparison_value);
3745 /* If we don't get an invariant final value, we are better
3746 off with the original register. */
3747 if (!invariant_p (final_value))
3748 final_value = comparison_value;
3751 /* Calculate the approximate final value of the induction variable
3752 (on the last successful iteration). The exact final value
3753 depends on the branch operator, and increment sign. It will be
3754 wrong if the iteration variable is not incremented by one each
3755 time through the loop and (comparison_value + off_by_one -
3756 initial_value) % increment != 0.
3757 ??? Note that the final_value may overflow and thus final_larger
3758 will be bogus. A potentially infinite loop will be classified
3759 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3761 final_value = plus_constant (final_value, off_by_one);
3763 /* Save the calculated values describing this loop's bounds, in case
3764 precondition_loop_p will need them later. These values can not be
3765 recalculated inside precondition_loop_p because strength reduction
3766 optimizations may obscure the loop's structure.
3768 These values are only required by precondition_loop_p and insert_bct
3769 whenever the number of iterations cannot be computed at compile time.
3770 Only the difference between final_value and initial_value is
3771 important. Note that final_value is only approximate. */
3772 loop_info->initial_value = initial_value;
3773 loop_info->comparison_value = comparison_value;
3774 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3775 loop_info->increment = increment;
3776 loop_info->iteration_var = iteration_var;
3777 loop_info->comparison_code = comparison_code;
3779 /* Try to determine the iteration count for loops such
3780 as (for i = init; i < init + const; i++). When running the
3781 loop optimization twice, the first pass often converts simple
3782 loops into this form. */
3784 if (REG_P (initial_value))
3790 reg1 = initial_value;
3791 if (GET_CODE (final_value) == PLUS)
3792 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3794 reg2 = final_value, const2 = const0_rtx;
3796 /* Check for initial_value = reg1, final_value = reg2 + const2,
3797 where reg1 != reg2. */
3798 if (REG_P (reg2) && reg2 != reg1)
3802 /* Find what reg1 is equivalent to. Hopefully it will
3803 either be reg2 or reg2 plus a constant. */
3804 temp = loop_find_equiv_value (loop_start, reg1);
3805 if (find_common_reg_term (temp, reg2))
3806 initial_value = temp;
3809 /* Find what reg2 is equivalent to. Hopefully it will
3810 either be reg1 or reg1 plus a constant. Let's ignore
3811 the latter case for now since it is not so common. */
3812 temp = loop_find_equiv_value (loop_start, reg2);
3813 if (temp == loop_info->iteration_var)
3814 temp = initial_value;
3816 final_value = (const2 == const0_rtx)
3817 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3820 else if (loop_info->vtop && GET_CODE (reg2) == CONST_INT)
3824 /* When running the loop optimizer twice, check_dbra_loop
3825 further obfuscates reversible loops of the form:
3826 for (i = init; i < init + const; i++). We often end up with
3827 final_value = 0, initial_value = temp, temp = temp2 - init,
3828 where temp2 = init + const. If the loop has a vtop we
3829 can replace initial_value with const. */
3831 temp = loop_find_equiv_value (loop_start, reg1);
3832 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3834 rtx temp2 = loop_find_equiv_value (loop_start, XEXP (temp, 0));
3835 if (GET_CODE (temp2) == PLUS
3836 && XEXP (temp2, 0) == XEXP (temp, 1))
3837 initial_value = XEXP (temp2, 1);
3842 /* If have initial_value = reg + const1 and final_value = reg +
3843 const2, then replace initial_value with const1 and final_value
3844 with const2. This should be safe since we are protected by the
3845 initial comparison before entering the loop if we have a vtop.
3846 For example, a + b < a + c is not equivalent to b < c for all a
3847 when using modulo arithmetic.
3849 ??? Without a vtop we could still perform the optimization if we check
3850 the initial and final values carefully. */
3852 && (reg_term = find_common_reg_term (initial_value, final_value)))
3854 initial_value = subtract_reg_term (initial_value, reg_term);
3855 final_value = subtract_reg_term (final_value, reg_term);
3858 loop_info->initial_equiv_value = initial_value;
3859 loop_info->final_equiv_value = final_value;
3861 /* For EQ comparison loops, we don't have a valid final value.
3862 Check this now so that we won't leave an invalid value if we
3863 return early for any other reason. */
3864 if (comparison_code == EQ)
3865 loop_info->final_equiv_value = loop_info->final_value = 0;
3869 if (loop_dump_stream)
3870 fprintf (loop_dump_stream,
3871 "Loop iterations: Increment value can't be calculated.\n");
3875 if (GET_CODE (increment) != CONST_INT)
3877 /* If we have a REG, check to see if REG holds a constant value. */
3878 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3879 clear if it is worthwhile to try to handle such RTL. */
3880 if (GET_CODE (increment) == REG || GET_CODE (increment) == SUBREG)
3881 increment = loop_find_equiv_value (loop_start, increment);
3883 if (GET_CODE (increment) != CONST_INT)
3885 if (loop_dump_stream)
3887 fprintf (loop_dump_stream,
3888 "Loop iterations: Increment value not constant ");
3889 print_rtl (loop_dump_stream, increment);
3890 fprintf (loop_dump_stream, ".\n");
3894 loop_info->increment = increment;
3897 if (GET_CODE (initial_value) != CONST_INT)
3899 if (loop_dump_stream)
3901 fprintf (loop_dump_stream,
3902 "Loop iterations: Initial value not constant ");
3903 print_rtl (loop_dump_stream, initial_value);
3904 fprintf (loop_dump_stream, ".\n");
3908 else if (comparison_code == EQ)
3910 if (loop_dump_stream)
3911 fprintf (loop_dump_stream,
3912 "Loop iterations: EQ comparison loop.\n");
3915 else if (GET_CODE (final_value) != CONST_INT)
3917 if (loop_dump_stream)
3919 fprintf (loop_dump_stream,
3920 "Loop iterations: Final value not constant ");
3921 print_rtl (loop_dump_stream, final_value);
3922 fprintf (loop_dump_stream, ".\n");
3927 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3930 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3931 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3932 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3933 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3935 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3936 - (INTVAL (final_value) < INTVAL (initial_value));
3938 if (INTVAL (increment) > 0)
3940 else if (INTVAL (increment) == 0)
3945 /* There are 27 different cases: compare_dir = -1, 0, 1;
3946 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3947 There are 4 normal cases, 4 reverse cases (where the iteration variable
3948 will overflow before the loop exits), 4 infinite loop cases, and 15
3949 immediate exit (0 or 1 iteration depending on loop type) cases.
3950 Only try to optimize the normal cases. */
3952 /* (compare_dir/final_larger/increment_dir)
3953 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3954 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3955 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3956 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3958 /* ?? If the meaning of reverse loops (where the iteration variable
3959 will overflow before the loop exits) is undefined, then could
3960 eliminate all of these special checks, and just always assume
3961 the loops are normal/immediate/infinite. Note that this means
3962 the sign of increment_dir does not have to be known. Also,
3963 since it does not really hurt if immediate exit loops or infinite loops
3964 are optimized, then that case could be ignored also, and hence all
3965 loops can be optimized.
3967 According to ANSI Spec, the reverse loop case result is undefined,
3968 because the action on overflow is undefined.
3970 See also the special test for NE loops below. */
3972 if (final_larger == increment_dir && final_larger != 0
3973 && (final_larger == compare_dir || compare_dir == 0))
3978 if (loop_dump_stream)
3979 fprintf (loop_dump_stream,
3980 "Loop iterations: Not normal loop.\n");
3984 /* Calculate the number of iterations, final_value is only an approximation,
3985 so correct for that. Note that abs_diff and n_iterations are
3986 unsigned, because they can be as large as 2^n - 1. */
3988 abs_inc = INTVAL (increment);
3990 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
3991 else if (abs_inc < 0)
3993 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
3999 /* For NE tests, make sure that the iteration variable won't miss
4000 the final value. If abs_diff mod abs_incr is not zero, then the
4001 iteration variable will overflow before the loop exits, and we
4002 can not calculate the number of iterations. */
4003 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
4006 /* Note that the number of iterations could be calculated using
4007 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4008 handle potential overflow of the summation. */
4009 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
4010 return loop_info->n_iterations;
4014 /* Replace uses of split bivs with their split pseudo register. This is
4015 for original instructions which remain after loop unrolling without
4019 remap_split_bivs (x)
4022 register enum rtx_code code;
4029 code = GET_CODE (x);
4044 /* If non-reduced/final-value givs were split, then this would also
4045 have to remap those givs also. */
4047 if (REGNO (x) < max_reg_before_loop
4048 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
4049 return reg_biv_class[REGNO (x)]->biv->src_reg;
4056 fmt = GET_RTX_FORMAT (code);
4057 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4060 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
4064 for (j = 0; j < XVECLEN (x, i); j++)
4065 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
4071 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4072 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4073 return 0. COPY_START is where we can start looking for the insns
4074 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4077 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4078 must dominate LAST_UID.
4080 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4081 may not dominate LAST_UID.
4083 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4084 must dominate LAST_UID. */
4087 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
4094 int passed_jump = 0;
4095 rtx p = NEXT_INSN (copy_start);
4097 while (INSN_UID (p) != first_uid)
4099 if (GET_CODE (p) == JUMP_INSN)
4101 /* Could not find FIRST_UID. */
4107 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4108 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
4109 || ! dead_or_set_regno_p (p, regno))
4112 /* FIRST_UID is always executed. */
4113 if (passed_jump == 0)
4116 while (INSN_UID (p) != last_uid)
4118 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4119 can not be sure that FIRST_UID dominates LAST_UID. */
4120 if (GET_CODE (p) == CODE_LABEL)
4122 /* Could not find LAST_UID, but we reached the end of the loop, so
4124 else if (p == copy_end)
4129 /* FIRST_UID is always executed if LAST_UID is executed. */