1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 93, 94, 95, 97, 98, 1999 Free Software Foundation, Inc.
3 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* Try to unroll a loop, and split induction variables.
24 Loops for which the number of iterations can be calculated exactly are
25 handled specially. If the number of iterations times the insn_count is
26 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
27 Otherwise, we try to unroll the loop a number of times modulo the number
28 of iterations, so that only one exit test will be needed. It is unrolled
29 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
32 Otherwise, if the number of iterations can be calculated exactly at
33 run time, and the loop is always entered at the top, then we try to
34 precondition the loop. That is, at run time, calculate how many times
35 the loop will execute, and then execute the loop body a few times so
36 that the remaining iterations will be some multiple of 4 (or 2 if the
37 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
38 with only one exit test needed at the end of the loop.
40 Otherwise, if the number of iterations can not be calculated exactly,
41 not even at run time, then we still unroll the loop a number of times
42 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
43 but there must be an exit test after each copy of the loop body.
45 For each induction variable, which is dead outside the loop (replaceable)
46 or for which we can easily calculate the final value, if we can easily
47 calculate its value at each place where it is set as a function of the
48 current loop unroll count and the variable's value at loop entry, then
49 the induction variable is split into `N' different variables, one for
50 each copy of the loop body. One variable is live across the backward
51 branch, and the others are all calculated as a function of this variable.
52 This helps eliminate data dependencies, and leads to further opportunities
55 /* Possible improvements follow: */
57 /* ??? Add an extra pass somewhere to determine whether unrolling will
58 give any benefit. E.g. after generating all unrolled insns, compute the
59 cost of all insns and compare against cost of insns in rolled loop.
61 - On traditional architectures, unrolling a non-constant bound loop
62 is a win if there is a giv whose only use is in memory addresses, the
63 memory addresses can be split, and hence giv increments can be
65 - It is also a win if the loop is executed many times, and preconditioning
66 can be performed for the loop.
67 Add code to check for these and similar cases. */
69 /* ??? Improve control of which loops get unrolled. Could use profiling
70 info to only unroll the most commonly executed loops. Perhaps have
71 a user specifyable option to control the amount of code expansion,
72 or the percent of loops to consider for unrolling. Etc. */
74 /* ??? Look at the register copies inside the loop to see if they form a
75 simple permutation. If so, iterate the permutation until it gets back to
76 the start state. This is how many times we should unroll the loop, for
77 best results, because then all register copies can be eliminated.
78 For example, the lisp nreverse function should be unrolled 3 times
87 ??? The number of times to unroll the loop may also be based on data
88 references in the loop. For example, if we have a loop that references
89 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
91 /* ??? Add some simple linear equation solving capability so that we can
92 determine the number of loop iterations for more complex loops.
93 For example, consider this loop from gdb
94 #define SWAP_TARGET_AND_HOST(buffer,len)
97 char *p = (char *) buffer;
98 char *q = ((char *) buffer) + len - 1;
99 int iterations = (len + 1) >> 1;
101 for (p; p < q; p++, q--;)
109 start value = p = &buffer + current_iteration
110 end value = q = &buffer + len - 1 - current_iteration
111 Given the loop exit test of "p < q", then there must be "q - p" iterations,
112 set equal to zero and solve for number of iterations:
113 q - p = len - 1 - 2*current_iteration = 0
114 current_iteration = (len - 1) / 2
115 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
116 iterations of this loop. */
118 /* ??? Currently, no labels are marked as loop invariant when doing loop
119 unrolling. This is because an insn inside the loop, that loads the address
120 of a label inside the loop into a register, could be moved outside the loop
121 by the invariant code motion pass if labels were invariant. If the loop
122 is subsequently unrolled, the code will be wrong because each unrolled
123 body of the loop will use the same address, whereas each actually needs a
124 different address. A case where this happens is when a loop containing
125 a switch statement is unrolled.
127 It would be better to let labels be considered invariant. When we
128 unroll loops here, check to see if any insns using a label local to the
129 loop were moved before the loop. If so, then correct the problem, by
130 moving the insn back into the loop, or perhaps replicate the insn before
131 the loop, one copy for each time the loop is unrolled. */
133 /* The prime factors looked for when trying to unroll a loop by some
134 number which is modulo the total number of iterations. Just checking
135 for these 4 prime factors will find at least one factor for 75% of
136 all numbers theoretically. Practically speaking, this will succeed
137 almost all of the time since loops are generally a multiple of 2
140 #define NUM_FACTORS 4
142 struct _factor { int factor, count; } factors[NUM_FACTORS]
143 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
145 /* Describes the different types of loop unrolling performed. */
147 enum unroll_types { UNROLL_COMPLETELY, UNROLL_MODULO, UNROLL_NAIVE };
152 #include "insn-config.h"
153 #include "integrate.h"
161 /* This controls which loops are unrolled, and by how much we unroll
164 #ifndef MAX_UNROLLED_INSNS
165 #define MAX_UNROLLED_INSNS 100
168 /* Indexed by register number, if non-zero, then it contains a pointer
169 to a struct induction for a DEST_REG giv which has been combined with
170 one of more address givs. This is needed because whenever such a DEST_REG
171 giv is modified, we must modify the value of all split address givs
172 that were combined with this DEST_REG giv. */
174 static struct induction **addr_combined_regs;
176 /* Indexed by register number, if this is a splittable induction variable,
177 then this will hold the current value of the register, which depends on the
180 static rtx *splittable_regs;
182 /* Indexed by register number, if this is a splittable induction variable,
183 this indicates if it was made from a derived giv. */
184 static char *derived_regs;
186 /* Indexed by register number, if this is a splittable induction variable,
187 then this will hold the number of instructions in the loop that modify
188 the induction variable. Used to ensure that only the last insn modifying
189 a split iv will update the original iv of the dest. */
191 static int *splittable_regs_updates;
193 /* Forward declarations. */
195 static void init_reg_map PROTO((struct inline_remap *, int));
196 static rtx calculate_giv_inc PROTO((rtx, rtx, int));
197 static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
198 static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
199 static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
200 enum unroll_types, rtx, rtx, rtx, rtx));
201 static void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
202 static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int,
203 unsigned HOST_WIDE_INT));
204 static int find_splittable_givs PROTO((struct iv_class *, enum unroll_types,
205 rtx, rtx, rtx, int));
206 static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
207 static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
208 static int verify_addresses PROTO((struct induction *, rtx, int));
209 static rtx remap_split_bivs PROTO((rtx));
211 /* Try to unroll one loop and split induction variables in the loop.
213 The loop is described by the arguments LOOP_END, INSN_COUNT, and
214 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
215 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
216 indicates whether information generated in the strength reduction pass
219 This function is intended to be called from within `strength_reduce'
223 unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
224 loop_info, strength_reduce_p)
228 rtx end_insert_before;
229 struct loop_info *loop_info;
230 int strength_reduce_p;
233 int unroll_number = 1;
234 rtx copy_start, copy_end;
235 rtx insn, sequence, pattern, tem;
236 int max_labelno, max_insnno;
238 struct inline_remap *map;
246 int splitting_not_safe = 0;
247 enum unroll_types unroll_type;
248 int loop_preconditioned = 0;
250 /* This points to the last real insn in the loop, which should be either
251 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
255 /* Don't bother unrolling huge loops. Since the minimum factor is
256 two, loops greater than one half of MAX_UNROLLED_INSNS will never
258 if (insn_count > MAX_UNROLLED_INSNS / 2)
260 if (loop_dump_stream)
261 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
265 /* When emitting debugger info, we can't unroll loops with unequal numbers
266 of block_beg and block_end notes, because that would unbalance the block
267 structure of the function. This can happen as a result of the
268 "if (foo) bar; else break;" optimization in jump.c. */
269 /* ??? Gcc has a general policy that -g is never supposed to change the code
270 that the compiler emits, so we must disable this optimization always,
271 even if debug info is not being output. This is rare, so this should
272 not be a significant performance problem. */
274 if (1 /* write_symbols != NO_DEBUG */)
276 int block_begins = 0;
279 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
281 if (GET_CODE (insn) == NOTE)
283 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
285 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
290 if (block_begins != block_ends)
292 if (loop_dump_stream)
293 fprintf (loop_dump_stream,
294 "Unrolling failure: Unbalanced block notes.\n");
299 /* Determine type of unroll to perform. Depends on the number of iterations
300 and the size of the loop. */
302 /* If there is no strength reduce info, then set
303 loop_info->n_iterations to zero. This can happen if
304 strength_reduce can't find any bivs in the loop. A value of zero
305 indicates that the number of iterations could not be calculated. */
307 if (! strength_reduce_p)
308 loop_info->n_iterations = 0;
310 if (loop_dump_stream && loop_info->n_iterations > 0)
312 fputs ("Loop unrolling: ", loop_dump_stream);
313 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
314 loop_info->n_iterations);
315 fputs (" iterations.\n", loop_dump_stream);
318 /* Find and save a pointer to the last nonnote insn in the loop. */
320 last_loop_insn = prev_nonnote_insn (loop_end);
322 /* Calculate how many times to unroll the loop. Indicate whether or
323 not the loop is being completely unrolled. */
325 if (loop_info->n_iterations == 1)
327 /* If number of iterations is exactly 1, then eliminate the compare and
328 branch at the end of the loop since they will never be taken.
329 Then return, since no other action is needed here. */
331 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
332 don't do anything. */
334 if (GET_CODE (last_loop_insn) == BARRIER)
336 /* Delete the jump insn. This will delete the barrier also. */
337 delete_insn (PREV_INSN (last_loop_insn));
339 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
342 /* The immediately preceding insn is a compare which must be
344 delete_insn (last_loop_insn);
345 delete_insn (PREV_INSN (last_loop_insn));
347 /* The immediately preceding insn may not be the compare, so don't
349 delete_insn (last_loop_insn);
354 else if (loop_info->n_iterations > 0
355 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
357 unroll_number = loop_info->n_iterations;
358 unroll_type = UNROLL_COMPLETELY;
360 else if (loop_info->n_iterations > 0)
362 /* Try to factor the number of iterations. Don't bother with the
363 general case, only using 2, 3, 5, and 7 will get 75% of all
364 numbers theoretically, and almost all in practice. */
366 for (i = 0; i < NUM_FACTORS; i++)
367 factors[i].count = 0;
369 temp = loop_info->n_iterations;
370 for (i = NUM_FACTORS - 1; i >= 0; i--)
371 while (temp % factors[i].factor == 0)
374 temp = temp / factors[i].factor;
377 /* Start with the larger factors first so that we generally
378 get lots of unrolling. */
382 for (i = 3; i >= 0; i--)
383 while (factors[i].count--)
385 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
387 unroll_number *= factors[i].factor;
388 temp *= factors[i].factor;
394 /* If we couldn't find any factors, then unroll as in the normal
396 if (unroll_number == 1)
398 if (loop_dump_stream)
399 fprintf (loop_dump_stream,
400 "Loop unrolling: No factors found.\n");
403 unroll_type = UNROLL_MODULO;
407 /* Default case, calculate number of times to unroll loop based on its
409 if (unroll_number == 1)
411 if (8 * insn_count < MAX_UNROLLED_INSNS)
413 else if (4 * insn_count < MAX_UNROLLED_INSNS)
418 unroll_type = UNROLL_NAIVE;
421 /* Now we know how many times to unroll the loop. */
423 if (loop_dump_stream)
424 fprintf (loop_dump_stream,
425 "Unrolling loop %d times.\n", unroll_number);
428 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
430 /* Loops of these types can start with jump down to the exit condition
431 in rare circumstances.
433 Consider a pair of nested loops where the inner loop is part
434 of the exit code for the outer loop.
436 In this case jump.c will not duplicate the exit test for the outer
437 loop, so it will start with a jump to the exit code.
439 Then consider if the inner loop turns out to iterate once and
440 only once. We will end up deleting the jumps associated with
441 the inner loop. However, the loop notes are not removed from
442 the instruction stream.
444 And finally assume that we can compute the number of iterations
447 In this case unroll may want to unroll the outer loop even though
448 it starts with a jump to the outer loop's exit code.
450 We could try to optimize this case, but it hardly seems worth it.
451 Just return without unrolling the loop in such cases. */
454 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
455 insn = NEXT_INSN (insn);
456 if (GET_CODE (insn) == JUMP_INSN)
460 if (unroll_type == UNROLL_COMPLETELY)
462 /* Completely unrolling the loop: Delete the compare and branch at
463 the end (the last two instructions). This delete must done at the
464 very end of loop unrolling, to avoid problems with calls to
465 back_branch_in_range_p, which is called by find_splittable_regs.
466 All increments of splittable bivs/givs are changed to load constant
469 copy_start = loop_start;
471 /* Set insert_before to the instruction immediately after the JUMP_INSN
472 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
473 the loop will be correctly handled by copy_loop_body. */
474 insert_before = NEXT_INSN (last_loop_insn);
476 /* Set copy_end to the insn before the jump at the end of the loop. */
477 if (GET_CODE (last_loop_insn) == BARRIER)
478 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
479 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
482 /* The instruction immediately before the JUMP_INSN is a compare
483 instruction which we do not want to copy. */
484 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
486 /* The instruction immediately before the JUMP_INSN may not be the
487 compare, so we must copy it. */
488 copy_end = PREV_INSN (last_loop_insn);
493 /* We currently can't unroll a loop if it doesn't end with a
494 JUMP_INSN. There would need to be a mechanism that recognizes
495 this case, and then inserts a jump after each loop body, which
496 jumps to after the last loop body. */
497 if (loop_dump_stream)
498 fprintf (loop_dump_stream,
499 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
503 else if (unroll_type == UNROLL_MODULO)
505 /* Partially unrolling the loop: The compare and branch at the end
506 (the last two instructions) must remain. Don't copy the compare
507 and branch instructions at the end of the loop. Insert the unrolled
508 code immediately before the compare/branch at the end so that the
509 code will fall through to them as before. */
511 copy_start = loop_start;
513 /* Set insert_before to the jump insn at the end of the loop.
514 Set copy_end to before the jump insn at the end of the loop. */
515 if (GET_CODE (last_loop_insn) == BARRIER)
517 insert_before = PREV_INSN (last_loop_insn);
518 copy_end = PREV_INSN (insert_before);
520 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
523 /* The instruction immediately before the JUMP_INSN is a compare
524 instruction which we do not want to copy or delete. */
525 insert_before = PREV_INSN (last_loop_insn);
526 copy_end = PREV_INSN (insert_before);
528 /* The instruction immediately before the JUMP_INSN may not be the
529 compare, so we must copy it. */
530 insert_before = last_loop_insn;
531 copy_end = PREV_INSN (last_loop_insn);
536 /* We currently can't unroll a loop if it doesn't end with a
537 JUMP_INSN. There would need to be a mechanism that recognizes
538 this case, and then inserts a jump after each loop body, which
539 jumps to after the last loop body. */
540 if (loop_dump_stream)
541 fprintf (loop_dump_stream,
542 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
548 /* Normal case: Must copy the compare and branch instructions at the
551 if (GET_CODE (last_loop_insn) == BARRIER)
553 /* Loop ends with an unconditional jump and a barrier.
554 Handle this like above, don't copy jump and barrier.
555 This is not strictly necessary, but doing so prevents generating
556 unconditional jumps to an immediately following label.
558 This will be corrected below if the target of this jump is
559 not the start_label. */
561 insert_before = PREV_INSN (last_loop_insn);
562 copy_end = PREV_INSN (insert_before);
564 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
566 /* Set insert_before to immediately after the JUMP_INSN, so that
567 NOTEs at the end of the loop will be correctly handled by
569 insert_before = NEXT_INSN (last_loop_insn);
570 copy_end = last_loop_insn;
574 /* We currently can't unroll a loop if it doesn't end with a
575 JUMP_INSN. There would need to be a mechanism that recognizes
576 this case, and then inserts a jump after each loop body, which
577 jumps to after the last loop body. */
578 if (loop_dump_stream)
579 fprintf (loop_dump_stream,
580 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
584 /* If copying exit test branches because they can not be eliminated,
585 then must convert the fall through case of the branch to a jump past
586 the end of the loop. Create a label to emit after the loop and save
587 it for later use. Do not use the label after the loop, if any, since
588 it might be used by insns outside the loop, or there might be insns
589 added before it later by final_[bg]iv_value which must be after
590 the real exit label. */
591 exit_label = gen_label_rtx ();
594 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
595 insn = NEXT_INSN (insn);
597 if (GET_CODE (insn) == JUMP_INSN)
599 /* The loop starts with a jump down to the exit condition test.
600 Start copying the loop after the barrier following this
602 copy_start = NEXT_INSN (insn);
604 /* Splitting induction variables doesn't work when the loop is
605 entered via a jump to the bottom, because then we end up doing
606 a comparison against a new register for a split variable, but
607 we did not execute the set insn for the new register because
608 it was skipped over. */
609 splitting_not_safe = 1;
610 if (loop_dump_stream)
611 fprintf (loop_dump_stream,
612 "Splitting not safe, because loop not entered at top.\n");
615 copy_start = loop_start;
618 /* This should always be the first label in the loop. */
619 start_label = NEXT_INSN (copy_start);
620 /* There may be a line number note and/or a loop continue note here. */
621 while (GET_CODE (start_label) == NOTE)
622 start_label = NEXT_INSN (start_label);
623 if (GET_CODE (start_label) != CODE_LABEL)
625 /* This can happen as a result of jump threading. If the first insns in
626 the loop test the same condition as the loop's backward jump, or the
627 opposite condition, then the backward jump will be modified to point
628 to elsewhere, and the loop's start label is deleted.
630 This case currently can not be handled by the loop unrolling code. */
632 if (loop_dump_stream)
633 fprintf (loop_dump_stream,
634 "Unrolling failure: unknown insns between BEG note and loop label.\n");
637 if (LABEL_NAME (start_label))
639 /* The jump optimization pass must have combined the original start label
640 with a named label for a goto. We can't unroll this case because
641 jumps which go to the named label must be handled differently than
642 jumps to the loop start, and it is impossible to differentiate them
644 if (loop_dump_stream)
645 fprintf (loop_dump_stream,
646 "Unrolling failure: loop start label is gone\n");
650 if (unroll_type == UNROLL_NAIVE
651 && GET_CODE (last_loop_insn) == BARRIER
652 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
654 /* In this case, we must copy the jump and barrier, because they will
655 not be converted to jumps to an immediately following label. */
657 insert_before = NEXT_INSN (last_loop_insn);
658 copy_end = last_loop_insn;
661 if (unroll_type == UNROLL_NAIVE
662 && GET_CODE (last_loop_insn) == JUMP_INSN
663 && start_label != JUMP_LABEL (last_loop_insn))
665 /* ??? The loop ends with a conditional branch that does not branch back
666 to the loop start label. In this case, we must emit an unconditional
667 branch to the loop exit after emitting the final branch.
668 copy_loop_body does not have support for this currently, so we
669 give up. It doesn't seem worthwhile to unroll anyways since
670 unrolling would increase the number of branch instructions
672 if (loop_dump_stream)
673 fprintf (loop_dump_stream,
674 "Unrolling failure: final conditional branch not to loop start\n");
678 /* Allocate a translation table for the labels and insn numbers.
679 They will be filled in as we copy the insns in the loop. */
681 max_labelno = max_label_num ();
682 max_insnno = get_max_uid ();
684 map = (struct inline_remap *) alloca (sizeof (struct inline_remap));
686 map->integrating = 0;
688 /* Allocate the label map. */
692 map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx));
694 local_label = (char *) alloca (max_labelno);
695 bzero (local_label, max_labelno);
700 /* Search the loop and mark all local labels, i.e. the ones which have to
701 be distinct labels when copied. For all labels which might be
702 non-local, set their label_map entries to point to themselves.
703 If they happen to be local their label_map entries will be overwritten
704 before the loop body is copied. The label_map entries for local labels
705 will be set to a different value each time the loop body is copied. */
707 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
711 if (GET_CODE (insn) == CODE_LABEL)
712 local_label[CODE_LABEL_NUMBER (insn)] = 1;
713 else if (GET_CODE (insn) == JUMP_INSN)
715 if (JUMP_LABEL (insn))
716 set_label_in_map (map,
717 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
719 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
720 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
722 rtx pat = PATTERN (insn);
723 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
724 int len = XVECLEN (pat, diff_vec_p);
727 for (i = 0; i < len; i++)
729 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
730 set_label_in_map (map,
731 CODE_LABEL_NUMBER (label),
736 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
737 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
741 /* Allocate space for the insn map. */
743 map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx));
745 /* Set this to zero, to indicate that we are doing loop unrolling,
746 not function inlining. */
747 map->inline_target = 0;
749 /* The register and constant maps depend on the number of registers
750 present, so the final maps can't be created until after
751 find_splittable_regs is called. However, they are needed for
752 preconditioning, so we create temporary maps when preconditioning
755 /* The preconditioning code may allocate two new pseudo registers. */
756 maxregnum = max_reg_num ();
758 /* Allocate and zero out the splittable_regs and addr_combined_regs
759 arrays. These must be zeroed here because they will be used if
760 loop preconditioning is performed, and must be zero for that case.
762 It is safe to do this here, since the extra registers created by the
763 preconditioning code and find_splittable_regs will never be used
764 to access the splittable_regs[] and addr_combined_regs[] arrays. */
766 splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx));
767 bzero ((char *) splittable_regs, maxregnum * sizeof (rtx));
768 derived_regs = alloca (maxregnum);
769 bzero (derived_regs, maxregnum);
770 splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int));
771 bzero ((char *) splittable_regs_updates, maxregnum * sizeof (int));
773 = (struct induction **) alloca (maxregnum * sizeof (struct induction *));
774 bzero ((char *) addr_combined_regs, maxregnum * sizeof (struct induction *));
775 local_regno = (char *) alloca (maxregnum);
776 bzero (local_regno, maxregnum);
778 /* Mark all local registers, i.e. the ones which are referenced only
780 if (INSN_UID (copy_end) < max_uid_for_loop)
782 int copy_start_luid = INSN_LUID (copy_start);
783 int copy_end_luid = INSN_LUID (copy_end);
785 /* If a register is used in the jump insn, we must not duplicate it
786 since it will also be used outside the loop. */
787 if (GET_CODE (copy_end) == JUMP_INSN)
789 /* If copy_start points to the NOTE that starts the loop, then we must
790 use the next luid, because invariant pseudo-regs moved out of the loop
791 have their lifetimes modified to start here, but they are not safe
793 if (copy_start == loop_start)
796 /* If a pseudo's lifetime is entirely contained within this loop, then we
797 can use a different pseudo in each unrolled copy of the loop. This
798 results in better code. */
799 /* We must limit the generic test to max_reg_before_loop, because only
800 these pseudo registers have valid regno_first_uid info. */
801 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
802 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
803 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
804 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
805 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
807 /* However, we must also check for loop-carried dependencies.
808 If the value the pseudo has at the end of iteration X is
809 used by iteration X+1, then we can not use a different pseudo
810 for each unrolled copy of the loop. */
811 /* A pseudo is safe if regno_first_uid is a set, and this
812 set dominates all instructions from regno_first_uid to
814 /* ??? This check is simplistic. We would get better code if
815 this check was more sophisticated. */
816 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
817 copy_start, copy_end))
820 if (loop_dump_stream)
823 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
825 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
829 /* Givs that have been created from multiple biv increments always have
831 for (j = first_increment_giv; j <= last_increment_giv; j++)
834 if (loop_dump_stream)
835 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
839 /* If this loop requires exit tests when unrolled, check to see if we
840 can precondition the loop so as to make the exit tests unnecessary.
841 Just like variable splitting, this is not safe if the loop is entered
842 via a jump to the bottom. Also, can not do this if no strength
843 reduce info, because precondition_loop_p uses this info. */
845 /* Must copy the loop body for preconditioning before the following
846 find_splittable_regs call since that will emit insns which need to
847 be after the preconditioned loop copies, but immediately before the
848 unrolled loop copies. */
850 /* Also, it is not safe to split induction variables for the preconditioned
851 copies of the loop body. If we split induction variables, then the code
852 assumes that each induction variable can be represented as a function
853 of its initial value and the loop iteration number. This is not true
854 in this case, because the last preconditioned copy of the loop body
855 could be any iteration from the first up to the `unroll_number-1'th,
856 depending on the initial value of the iteration variable. Therefore
857 we can not split induction variables here, because we can not calculate
858 their value. Hence, this code must occur before find_splittable_regs
861 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
863 rtx initial_value, final_value, increment;
864 enum machine_mode mode;
866 if (precondition_loop_p (loop_start, loop_info,
867 &initial_value, &final_value, &increment,
872 int abs_inc, neg_inc;
874 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
876 map->const_equiv_map = (rtx *) alloca (maxregnum * sizeof (rtx));
877 map->const_age_map = (unsigned *) alloca (maxregnum
878 * sizeof (unsigned));
879 map->const_equiv_map_size = maxregnum;
880 global_const_equiv_map = map->const_equiv_map;
881 global_const_equiv_map_size = maxregnum;
883 init_reg_map (map, maxregnum);
885 /* Limit loop unrolling to 4, since this will make 7 copies of
887 if (unroll_number > 4)
890 /* Save the absolute value of the increment, and also whether or
891 not it is negative. */
893 abs_inc = INTVAL (increment);
902 /* Calculate the difference between the final and initial values.
903 Final value may be a (plus (reg x) (const_int 1)) rtx.
904 Let the following cse pass simplify this if initial value is
907 We must copy the final and initial values here to avoid
908 improperly shared rtl. */
910 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
911 copy_rtx (initial_value), NULL_RTX, 0,
914 /* Now calculate (diff % (unroll * abs (increment))) by using an
916 diff = expand_binop (GET_MODE (diff), and_optab, diff,
917 GEN_INT (unroll_number * abs_inc - 1),
918 NULL_RTX, 0, OPTAB_LIB_WIDEN);
920 /* Now emit a sequence of branches to jump to the proper precond
923 labels = (rtx *) alloca (sizeof (rtx) * unroll_number);
924 for (i = 0; i < unroll_number; i++)
925 labels[i] = gen_label_rtx ();
927 /* Check for the case where the initial value is greater than or
928 equal to the final value. In that case, we want to execute
929 exactly one loop iteration. The code below will fail for this
930 case. This check does not apply if the loop has a NE
931 comparison at the end. */
933 if (loop_info->comparison_code != NE)
935 emit_cmp_and_jump_insns (initial_value, final_value,
937 NULL_RTX, mode, 0, 0, labels[1]);
938 JUMP_LABEL (get_last_insn ()) = labels[1];
939 LABEL_NUSES (labels[1])++;
942 /* Assuming the unroll_number is 4, and the increment is 2, then
943 for a negative increment: for a positive increment:
944 diff = 0,1 precond 0 diff = 0,7 precond 0
945 diff = 2,3 precond 3 diff = 1,2 precond 1
946 diff = 4,5 precond 2 diff = 3,4 precond 2
947 diff = 6,7 precond 1 diff = 5,6 precond 3 */
949 /* We only need to emit (unroll_number - 1) branches here, the
950 last case just falls through to the following code. */
952 /* ??? This would give better code if we emitted a tree of branches
953 instead of the current linear list of branches. */
955 for (i = 0; i < unroll_number - 1; i++)
958 enum rtx_code cmp_code;
960 /* For negative increments, must invert the constant compared
961 against, except when comparing against zero. */
969 cmp_const = unroll_number - i;
978 emit_cmp_and_jump_insns (diff, GEN_INT (abs_inc * cmp_const),
979 cmp_code, NULL_RTX, mode, 0, 0,
981 JUMP_LABEL (get_last_insn ()) = labels[i];
982 LABEL_NUSES (labels[i])++;
985 /* If the increment is greater than one, then we need another branch,
986 to handle other cases equivalent to 0. */
988 /* ??? This should be merged into the code above somehow to help
989 simplify the code here, and reduce the number of branches emitted.
990 For the negative increment case, the branch here could easily
991 be merged with the `0' case branch above. For the positive
992 increment case, it is not clear how this can be simplified. */
997 enum rtx_code cmp_code;
1001 cmp_const = abs_inc - 1;
1006 cmp_const = abs_inc * (unroll_number - 1) + 1;
1010 emit_cmp_and_jump_insns (diff, GEN_INT (cmp_const), cmp_code,
1011 NULL_RTX, mode, 0, 0, labels[0]);
1012 JUMP_LABEL (get_last_insn ()) = labels[0];
1013 LABEL_NUSES (labels[0])++;
1016 sequence = gen_sequence ();
1018 emit_insn_before (sequence, loop_start);
1020 /* Only the last copy of the loop body here needs the exit
1021 test, so set copy_end to exclude the compare/branch here,
1022 and then reset it inside the loop when get to the last
1025 if (GET_CODE (last_loop_insn) == BARRIER)
1026 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1027 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1030 /* The immediately preceding insn is a compare which we do not
1032 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1034 /* The immediately preceding insn may not be a compare, so we
1036 copy_end = PREV_INSN (last_loop_insn);
1042 for (i = 1; i < unroll_number; i++)
1044 emit_label_after (labels[unroll_number - i],
1045 PREV_INSN (loop_start));
1047 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1048 bzero ((char *) map->const_equiv_map, maxregnum * sizeof (rtx));
1049 bzero ((char *) map->const_age_map,
1050 maxregnum * sizeof (unsigned));
1053 for (j = 0; j < max_labelno; j++)
1055 set_label_in_map (map, j, gen_label_rtx ());
1057 for (j = FIRST_PSEUDO_REGISTER; j < maxregnum; j++)
1060 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1061 record_base_value (REGNO (map->reg_map[j]),
1062 regno_reg_rtx[j], 0);
1064 /* The last copy needs the compare/branch insns at the end,
1065 so reset copy_end here if the loop ends with a conditional
1068 if (i == unroll_number - 1)
1070 if (GET_CODE (last_loop_insn) == BARRIER)
1071 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1073 copy_end = last_loop_insn;
1076 /* None of the copies are the `last_iteration', so just
1077 pass zero for that parameter. */
1078 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1079 unroll_type, start_label, loop_end,
1080 loop_start, copy_end);
1082 emit_label_after (labels[0], PREV_INSN (loop_start));
1084 if (GET_CODE (last_loop_insn) == BARRIER)
1086 insert_before = PREV_INSN (last_loop_insn);
1087 copy_end = PREV_INSN (insert_before);
1092 /* The immediately preceding insn is a compare which we do not
1094 insert_before = PREV_INSN (last_loop_insn);
1095 copy_end = PREV_INSN (insert_before);
1097 /* The immediately preceding insn may not be a compare, so we
1099 insert_before = last_loop_insn;
1100 copy_end = PREV_INSN (last_loop_insn);
1104 /* Set unroll type to MODULO now. */
1105 unroll_type = UNROLL_MODULO;
1106 loop_preconditioned = 1;
1110 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1111 the loop unless all loops are being unrolled. */
1112 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1114 if (loop_dump_stream)
1115 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1119 /* At this point, we are guaranteed to unroll the loop. */
1121 /* Keep track of the unroll factor for the loop. */
1122 if (unroll_type == UNROLL_COMPLETELY)
1123 loop_info->unroll_number = -1;
1125 loop_info->unroll_number = unroll_number;
1128 /* For each biv and giv, determine whether it can be safely split into
1129 a different variable for each unrolled copy of the loop body.
1130 We precalculate and save this info here, since computing it is
1133 Do this before deleting any instructions from the loop, so that
1134 back_branch_in_range_p will work correctly. */
1136 if (splitting_not_safe)
1139 temp = find_splittable_regs (unroll_type, loop_start, loop_end,
1140 end_insert_before, unroll_number,
1141 loop_info->n_iterations);
1143 /* find_splittable_regs may have created some new registers, so must
1144 reallocate the reg_map with the new larger size, and must realloc
1145 the constant maps also. */
1147 maxregnum = max_reg_num ();
1148 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
1150 init_reg_map (map, maxregnum);
1152 /* Space is needed in some of the map for new registers, so new_maxregnum
1153 is an (over)estimate of how many registers will exist at the end. */
1154 new_maxregnum = maxregnum + (temp * unroll_number * 2);
1156 /* Must realloc space for the constant maps, because the number of registers
1157 may have changed. */
1159 map->const_equiv_map = (rtx *) alloca (new_maxregnum * sizeof (rtx));
1160 map->const_age_map = (unsigned *) alloca (new_maxregnum * sizeof (unsigned));
1162 map->const_equiv_map_size = new_maxregnum;
1163 global_const_equiv_map = map->const_equiv_map;
1164 global_const_equiv_map_size = new_maxregnum;
1166 /* Search the list of bivs and givs to find ones which need to be remapped
1167 when split, and set their reg_map entry appropriately. */
1169 for (bl = loop_iv_list; bl; bl = bl->next)
1171 if (REGNO (bl->biv->src_reg) != bl->regno)
1172 map->reg_map[bl->regno] = bl->biv->src_reg;
1174 /* Currently, non-reduced/final-value givs are never split. */
1175 for (v = bl->giv; v; v = v->next_iv)
1176 if (REGNO (v->src_reg) != bl->regno)
1177 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1181 /* Use our current register alignment and pointer flags. */
1182 map->regno_pointer_flag = regno_pointer_flag;
1183 map->regno_pointer_align = regno_pointer_align;
1185 /* If the loop is being partially unrolled, and the iteration variables
1186 are being split, and are being renamed for the split, then must fix up
1187 the compare/jump instruction at the end of the loop to refer to the new
1188 registers. This compare isn't copied, so the registers used in it
1189 will never be replaced if it isn't done here. */
1191 if (unroll_type == UNROLL_MODULO)
1193 insn = NEXT_INSN (copy_end);
1194 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1195 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1198 /* For unroll_number times, make a copy of each instruction
1199 between copy_start and copy_end, and insert these new instructions
1200 before the end of the loop. */
1202 for (i = 0; i < unroll_number; i++)
1204 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1205 bzero ((char *) map->const_equiv_map, new_maxregnum * sizeof (rtx));
1206 bzero ((char *) map->const_age_map, new_maxregnum * sizeof (unsigned));
1209 for (j = 0; j < max_labelno; j++)
1211 set_label_in_map (map, j, gen_label_rtx ());
1213 for (j = FIRST_PSEUDO_REGISTER; j < maxregnum; j++)
1216 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1217 record_base_value (REGNO (map->reg_map[j]),
1218 regno_reg_rtx[j], 0);
1221 /* If loop starts with a branch to the test, then fix it so that
1222 it points to the test of the first unrolled copy of the loop. */
1223 if (i == 0 && loop_start != copy_start)
1225 insn = PREV_INSN (copy_start);
1226 pattern = PATTERN (insn);
1228 tem = get_label_from_map (map,
1230 (XEXP (SET_SRC (pattern), 0)));
1231 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1233 /* Set the jump label so that it can be used by later loop unrolling
1235 JUMP_LABEL (insn) = tem;
1236 LABEL_NUSES (tem)++;
1239 copy_loop_body (copy_start, copy_end, map, exit_label,
1240 i == unroll_number - 1, unroll_type, start_label,
1241 loop_end, insert_before, insert_before);
1244 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1245 insn to be deleted. This prevents any runaway delete_insn call from
1246 more insns that it should, as it always stops at a CODE_LABEL. */
1248 /* Delete the compare and branch at the end of the loop if completely
1249 unrolling the loop. Deleting the backward branch at the end also
1250 deletes the code label at the start of the loop. This is done at
1251 the very end to avoid problems with back_branch_in_range_p. */
1253 if (unroll_type == UNROLL_COMPLETELY)
1254 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1256 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1258 /* Delete all of the original loop instructions. Don't delete the
1259 LOOP_BEG note, or the first code label in the loop. */
1261 insn = NEXT_INSN (copy_start);
1262 while (insn != safety_label)
1264 if (insn != start_label)
1265 insn = delete_insn (insn);
1267 insn = NEXT_INSN (insn);
1270 /* Can now delete the 'safety' label emitted to protect us from runaway
1271 delete_insn calls. */
1272 if (INSN_DELETED_P (safety_label))
1274 delete_insn (safety_label);
1276 /* If exit_label exists, emit it after the loop. Doing the emit here
1277 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1278 This is needed so that mostly_true_jump in reorg.c will treat jumps
1279 to this loop end label correctly, i.e. predict that they are usually
1282 emit_label_after (exit_label, loop_end);
1285 /* Return true if the loop can be safely, and profitably, preconditioned
1286 so that the unrolled copies of the loop body don't need exit tests.
1288 This only works if final_value, initial_value and increment can be
1289 determined, and if increment is a constant power of 2.
1290 If increment is not a power of 2, then the preconditioning modulo
1291 operation would require a real modulo instead of a boolean AND, and this
1292 is not considered `profitable'. */
1294 /* ??? If the loop is known to be executed very many times, or the machine
1295 has a very cheap divide instruction, then preconditioning is a win even
1296 when the increment is not a power of 2. Use RTX_COST to compute
1297 whether divide is cheap.
1298 ??? A divide by constant doesn't actually need a divide, look at
1299 expand_divmod. The reduced cost of this optimized modulo is not
1300 reflected in RTX_COST. */
1303 precondition_loop_p (loop_start, loop_info,
1304 initial_value, final_value, increment, mode)
1306 struct loop_info *loop_info;
1307 rtx *initial_value, *final_value, *increment;
1308 enum machine_mode *mode;
1311 if (loop_info->n_iterations > 0)
1313 *initial_value = const0_rtx;
1314 *increment = const1_rtx;
1315 *final_value = GEN_INT (loop_info->n_iterations);
1318 if (loop_dump_stream)
1320 fputs ("Preconditioning: Success, number of iterations known, ",
1322 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1323 loop_info->n_iterations);
1324 fputs (".\n", loop_dump_stream);
1329 if (loop_info->initial_value == 0)
1331 if (loop_dump_stream)
1332 fprintf (loop_dump_stream,
1333 "Preconditioning: Could not find initial value.\n");
1336 else if (loop_info->increment == 0)
1338 if (loop_dump_stream)
1339 fprintf (loop_dump_stream,
1340 "Preconditioning: Could not find increment value.\n");
1343 else if (GET_CODE (loop_info->increment) != CONST_INT)
1345 if (loop_dump_stream)
1346 fprintf (loop_dump_stream,
1347 "Preconditioning: Increment not a constant.\n");
1350 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1351 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1353 if (loop_dump_stream)
1354 fprintf (loop_dump_stream,
1355 "Preconditioning: Increment not a constant power of 2.\n");
1359 /* Unsigned_compare and compare_dir can be ignored here, since they do
1360 not matter for preconditioning. */
1362 if (loop_info->final_value == 0)
1364 if (loop_dump_stream)
1365 fprintf (loop_dump_stream,
1366 "Preconditioning: EQ comparison loop.\n");
1370 /* Must ensure that final_value is invariant, so call invariant_p to
1371 check. Before doing so, must check regno against max_reg_before_loop
1372 to make sure that the register is in the range covered by invariant_p.
1373 If it isn't, then it is most likely a biv/giv which by definition are
1375 if ((GET_CODE (loop_info->final_value) == REG
1376 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1377 || (GET_CODE (loop_info->final_value) == PLUS
1378 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1379 || ! invariant_p (loop_info->final_value))
1381 if (loop_dump_stream)
1382 fprintf (loop_dump_stream,
1383 "Preconditioning: Final value not invariant.\n");
1387 /* Fail for floating point values, since the caller of this function
1388 does not have code to deal with them. */
1389 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1390 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1392 if (loop_dump_stream)
1393 fprintf (loop_dump_stream,
1394 "Preconditioning: Floating point final or initial value.\n");
1398 /* Fail if loop_info->iteration_var is not live before loop_start,
1399 since we need to test its value in the preconditioning code. */
1401 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1402 > INSN_LUID (loop_start))
1404 if (loop_dump_stream)
1405 fprintf (loop_dump_stream,
1406 "Preconditioning: Iteration var not live before loop start.\n");
1410 /* ??? Note that if iteration_info is modifed to allow GIV iterators
1411 such as "while (i-- > 0)", the initial value will be one too small.
1412 In this case, loop_iteration_var could be used to determine
1413 the correct initial value, provided the loop has not been reversed.
1415 Also note that the absolute values of initial_value and
1416 final_value are unimportant as only their difference is used for
1417 calculating the number of loop iterations. */
1418 *initial_value = loop_info->initial_value;
1419 *increment = loop_info->increment;
1420 *final_value = loop_info->final_value;
1422 /* Decide what mode to do these calculations in. Choose the larger
1423 of final_value's mode and initial_value's mode, or a full-word if
1424 both are constants. */
1425 *mode = GET_MODE (*final_value);
1426 if (*mode == VOIDmode)
1428 *mode = GET_MODE (*initial_value);
1429 if (*mode == VOIDmode)
1432 else if (*mode != GET_MODE (*initial_value)
1433 && (GET_MODE_SIZE (*mode)
1434 < GET_MODE_SIZE (GET_MODE (*initial_value))))
1435 *mode = GET_MODE (*initial_value);
1438 if (loop_dump_stream)
1439 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1444 /* All pseudo-registers must be mapped to themselves. Two hard registers
1445 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1446 REGNUM, to avoid function-inlining specific conversions of these
1447 registers. All other hard regs can not be mapped because they may be
1452 init_reg_map (map, maxregnum)
1453 struct inline_remap *map;
1458 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1459 map->reg_map[i] = regno_reg_rtx[i];
1460 /* Just clear the rest of the entries. */
1461 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1462 map->reg_map[i] = 0;
1464 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1465 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1466 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1467 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1470 /* Strength-reduction will often emit code for optimized biv/givs which
1471 calculates their value in a temporary register, and then copies the result
1472 to the iv. This procedure reconstructs the pattern computing the iv;
1473 verifying that all operands are of the proper form.
1475 PATTERN must be the result of single_set.
1476 The return value is the amount that the giv is incremented by. */
1479 calculate_giv_inc (pattern, src_insn, regno)
1480 rtx pattern, src_insn;
1484 rtx increment_total = 0;
1488 /* Verify that we have an increment insn here. First check for a plus
1489 as the set source. */
1490 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1492 /* SR sometimes computes the new giv value in a temp, then copies it
1494 src_insn = PREV_INSN (src_insn);
1495 pattern = PATTERN (src_insn);
1496 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1499 /* The last insn emitted is not needed, so delete it to avoid confusing
1500 the second cse pass. This insn sets the giv unnecessarily. */
1501 delete_insn (get_last_insn ());
1504 /* Verify that we have a constant as the second operand of the plus. */
1505 increment = XEXP (SET_SRC (pattern), 1);
1506 if (GET_CODE (increment) != CONST_INT)
1508 /* SR sometimes puts the constant in a register, especially if it is
1509 too big to be an add immed operand. */
1510 src_insn = PREV_INSN (src_insn);
1511 increment = SET_SRC (PATTERN (src_insn));
1513 /* SR may have used LO_SUM to compute the constant if it is too large
1514 for a load immed operand. In this case, the constant is in operand
1515 one of the LO_SUM rtx. */
1516 if (GET_CODE (increment) == LO_SUM)
1517 increment = XEXP (increment, 1);
1519 /* Some ports store large constants in memory and add a REG_EQUAL
1520 note to the store insn. */
1521 else if (GET_CODE (increment) == MEM)
1523 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1525 increment = XEXP (note, 0);
1528 else if (GET_CODE (increment) == IOR
1529 || GET_CODE (increment) == ASHIFT
1530 || GET_CODE (increment) == PLUS)
1532 /* The rs6000 port loads some constants with IOR.
1533 The alpha port loads some constants with ASHIFT and PLUS. */
1534 rtx second_part = XEXP (increment, 1);
1535 enum rtx_code code = GET_CODE (increment);
1537 src_insn = PREV_INSN (src_insn);
1538 increment = SET_SRC (PATTERN (src_insn));
1539 /* Don't need the last insn anymore. */
1540 delete_insn (get_last_insn ());
1542 if (GET_CODE (second_part) != CONST_INT
1543 || GET_CODE (increment) != CONST_INT)
1547 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1548 else if (code == PLUS)
1549 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1551 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1554 if (GET_CODE (increment) != CONST_INT)
1557 /* The insn loading the constant into a register is no longer needed,
1559 delete_insn (get_last_insn ());
1562 if (increment_total)
1563 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1565 increment_total = increment;
1567 /* Check that the source register is the same as the register we expected
1568 to see as the source. If not, something is seriously wrong. */
1569 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1570 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1572 /* Some machines (e.g. the romp), may emit two add instructions for
1573 certain constants, so lets try looking for another add immediately
1574 before this one if we have only seen one add insn so far. */
1580 src_insn = PREV_INSN (src_insn);
1581 pattern = PATTERN (src_insn);
1583 delete_insn (get_last_insn ());
1591 return increment_total;
1594 /* Copy REG_NOTES, except for insn references, because not all insn_map
1595 entries are valid yet. We do need to copy registers now though, because
1596 the reg_map entries can change during copying. */
1599 initial_reg_note_copy (notes, map)
1601 struct inline_remap *map;
1608 copy = rtx_alloc (GET_CODE (notes));
1609 PUT_MODE (copy, GET_MODE (notes));
1611 if (GET_CODE (notes) == EXPR_LIST)
1612 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map);
1613 else if (GET_CODE (notes) == INSN_LIST)
1614 /* Don't substitute for these yet. */
1615 XEXP (copy, 0) = XEXP (notes, 0);
1619 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1624 /* Fixup insn references in copied REG_NOTES. */
1627 final_reg_note_copy (notes, map)
1629 struct inline_remap *map;
1633 for (note = notes; note; note = XEXP (note, 1))
1634 if (GET_CODE (note) == INSN_LIST)
1635 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1638 /* Copy each instruction in the loop, substituting from map as appropriate.
1639 This is very similar to a loop in expand_inline_function. */
1642 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1643 unroll_type, start_label, loop_end, insert_before,
1645 rtx copy_start, copy_end;
1646 struct inline_remap *map;
1649 enum unroll_types unroll_type;
1650 rtx start_label, loop_end, insert_before, copy_notes_from;
1654 int dest_reg_was_split, i;
1658 rtx final_label = 0;
1659 rtx giv_inc, giv_dest_reg, giv_src_reg;
1661 /* If this isn't the last iteration, then map any references to the
1662 start_label to final_label. Final label will then be emitted immediately
1663 after the end of this loop body if it was ever used.
1665 If this is the last iteration, then map references to the start_label
1667 if (! last_iteration)
1669 final_label = gen_label_rtx ();
1670 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1674 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1681 insn = NEXT_INSN (insn);
1683 map->orig_asm_operands_vector = 0;
1685 switch (GET_CODE (insn))
1688 pattern = PATTERN (insn);
1692 /* Check to see if this is a giv that has been combined with
1693 some split address givs. (Combined in the sense that
1694 `combine_givs' in loop.c has put two givs in the same register.)
1695 In this case, we must search all givs based on the same biv to
1696 find the address givs. Then split the address givs.
1697 Do this before splitting the giv, since that may map the
1698 SET_DEST to a new register. */
1700 if ((set = single_set (insn))
1701 && GET_CODE (SET_DEST (set)) == REG
1702 && addr_combined_regs[REGNO (SET_DEST (set))])
1704 struct iv_class *bl;
1705 struct induction *v, *tv;
1706 int regno = REGNO (SET_DEST (set));
1708 v = addr_combined_regs[REGNO (SET_DEST (set))];
1709 bl = reg_biv_class[REGNO (v->src_reg)];
1711 /* Although the giv_inc amount is not needed here, we must call
1712 calculate_giv_inc here since it might try to delete the
1713 last insn emitted. If we wait until later to call it,
1714 we might accidentally delete insns generated immediately
1715 below by emit_unrolled_add. */
1717 if (! derived_regs[regno])
1718 giv_inc = calculate_giv_inc (set, insn, regno);
1720 /* Now find all address giv's that were combined with this
1722 for (tv = bl->giv; tv; tv = tv->next_iv)
1723 if (tv->giv_type == DEST_ADDR && tv->same == v)
1727 /* If this DEST_ADDR giv was not split, then ignore it. */
1728 if (*tv->location != tv->dest_reg)
1731 /* Scale this_giv_inc if the multiplicative factors of
1732 the two givs are different. */
1733 this_giv_inc = INTVAL (giv_inc);
1734 if (tv->mult_val != v->mult_val)
1735 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1736 * INTVAL (tv->mult_val));
1738 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1739 *tv->location = tv->dest_reg;
1741 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1743 /* Must emit an insn to increment the split address
1744 giv. Add in the const_adjust field in case there
1745 was a constant eliminated from the address. */
1746 rtx value, dest_reg;
1748 /* tv->dest_reg will be either a bare register,
1749 or else a register plus a constant. */
1750 if (GET_CODE (tv->dest_reg) == REG)
1751 dest_reg = tv->dest_reg;
1753 dest_reg = XEXP (tv->dest_reg, 0);
1755 /* Check for shared address givs, and avoid
1756 incrementing the shared pseudo reg more than
1758 if (! tv->same_insn && ! tv->shared)
1760 /* tv->dest_reg may actually be a (PLUS (REG)
1761 (CONST)) here, so we must call plus_constant
1762 to add the const_adjust amount before calling
1763 emit_unrolled_add below. */
1764 value = plus_constant (tv->dest_reg,
1767 /* The constant could be too large for an add
1768 immediate, so can't directly emit an insn
1770 emit_unrolled_add (dest_reg, XEXP (value, 0),
1774 /* Reset the giv to be just the register again, in case
1775 it is used after the set we have just emitted.
1776 We must subtract the const_adjust factor added in
1778 tv->dest_reg = plus_constant (dest_reg,
1779 - tv->const_adjust);
1780 *tv->location = tv->dest_reg;
1785 /* If this is a setting of a splittable variable, then determine
1786 how to split the variable, create a new set based on this split,
1787 and set up the reg_map so that later uses of the variable will
1788 use the new split variable. */
1790 dest_reg_was_split = 0;
1792 if ((set = single_set (insn))
1793 && GET_CODE (SET_DEST (set)) == REG
1794 && splittable_regs[REGNO (SET_DEST (set))])
1796 int regno = REGNO (SET_DEST (set));
1799 dest_reg_was_split = 1;
1801 giv_dest_reg = SET_DEST (set);
1802 if (derived_regs[regno])
1804 giv_src_reg = XEXP (SET_SRC (set), 0);
1805 giv_inc = XEXP (SET_SRC (set), 1);
1809 giv_src_reg = giv_dest_reg;
1810 /* Compute the increment value for the giv, if it wasn't
1811 already computed above. */
1813 giv_inc = calculate_giv_inc (set, insn, regno);
1815 src_regno = REGNO (giv_src_reg);
1817 if (unroll_type == UNROLL_COMPLETELY)
1819 /* Completely unrolling the loop. Set the induction
1820 variable to a known constant value. */
1822 /* The value in splittable_regs may be an invariant
1823 value, so we must use plus_constant here. */
1824 splittable_regs[regno]
1825 = plus_constant (splittable_regs[src_regno],
1828 if (GET_CODE (splittable_regs[regno]) == PLUS)
1830 giv_src_reg = XEXP (splittable_regs[regno], 0);
1831 giv_inc = XEXP (splittable_regs[regno], 1);
1835 /* The splittable_regs value must be a REG or a
1836 CONST_INT, so put the entire value in the giv_src_reg
1838 giv_src_reg = splittable_regs[regno];
1839 giv_inc = const0_rtx;
1844 /* Partially unrolling loop. Create a new pseudo
1845 register for the iteration variable, and set it to
1846 be a constant plus the original register. Except
1847 on the last iteration, when the result has to
1848 go back into the original iteration var register. */
1850 /* Handle bivs which must be mapped to a new register
1851 when split. This happens for bivs which need their
1852 final value set before loop entry. The new register
1853 for the biv was stored in the biv's first struct
1854 induction entry by find_splittable_regs. */
1856 if (regno < max_reg_before_loop
1857 && REG_IV_TYPE (regno) == BASIC_INDUCT)
1859 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1860 giv_dest_reg = giv_src_reg;
1864 /* If non-reduced/final-value givs were split, then
1865 this would have to remap those givs also. See
1866 find_splittable_regs. */
1869 splittable_regs[regno]
1870 = GEN_INT (INTVAL (giv_inc)
1871 + INTVAL (splittable_regs[src_regno]));
1872 giv_inc = splittable_regs[regno];
1874 /* Now split the induction variable by changing the dest
1875 of this insn to a new register, and setting its
1876 reg_map entry to point to this new register.
1878 If this is the last iteration, and this is the last insn
1879 that will update the iv, then reuse the original dest,
1880 to ensure that the iv will have the proper value when
1881 the loop exits or repeats.
1883 Using splittable_regs_updates here like this is safe,
1884 because it can only be greater than one if all
1885 instructions modifying the iv are always executed in
1888 if (! last_iteration
1889 || (splittable_regs_updates[regno]-- != 1))
1891 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1893 map->reg_map[regno] = tem;
1894 record_base_value (REGNO (tem),
1895 giv_inc == const0_rtx
1897 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1898 giv_src_reg, giv_inc),
1902 map->reg_map[regno] = giv_src_reg;
1905 /* The constant being added could be too large for an add
1906 immediate, so can't directly emit an insn here. */
1907 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1908 copy = get_last_insn ();
1909 pattern = PATTERN (copy);
1913 pattern = copy_rtx_and_substitute (pattern, map);
1914 copy = emit_insn (pattern);
1916 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1919 /* If this insn is setting CC0, it may need to look at
1920 the insn that uses CC0 to see what type of insn it is.
1921 In that case, the call to recog via validate_change will
1922 fail. So don't substitute constants here. Instead,
1923 do it when we emit the following insn.
1925 For example, see the pyr.md file. That machine has signed and
1926 unsigned compares. The compare patterns must check the
1927 following branch insn to see which what kind of compare to
1930 If the previous insn set CC0, substitute constants on it as
1932 if (sets_cc0_p (PATTERN (copy)) != 0)
1937 try_constants (cc0_insn, map);
1939 try_constants (copy, map);
1942 try_constants (copy, map);
1945 /* Make split induction variable constants `permanent' since we
1946 know there are no backward branches across iteration variable
1947 settings which would invalidate this. */
1948 if (dest_reg_was_split)
1950 int regno = REGNO (SET_DEST (pattern));
1952 if (regno < map->const_equiv_map_size
1953 && map->const_age_map[regno] == map->const_age)
1954 map->const_age_map[regno] = -1;
1959 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
1960 copy = emit_jump_insn (pattern);
1961 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1963 if (JUMP_LABEL (insn) == start_label && insn == copy_end
1964 && ! last_iteration)
1966 /* This is a branch to the beginning of the loop; this is the
1967 last insn being copied; and this is not the last iteration.
1968 In this case, we want to change the original fall through
1969 case to be a branch past the end of the loop, and the
1970 original jump label case to fall_through. */
1972 if (invert_exp (pattern, copy))
1974 if (! redirect_exp (&pattern,
1975 get_label_from_map (map,
1977 (JUMP_LABEL (insn))),
1984 rtx lab = gen_label_rtx ();
1985 /* Can't do it by reversing the jump (probably because we
1986 couldn't reverse the conditions), so emit a new
1987 jump_insn after COPY, and redirect the jump around
1989 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
1990 jmp = emit_barrier_after (jmp);
1991 emit_label_after (lab, jmp);
1992 LABEL_NUSES (lab) = 0;
1993 if (! redirect_exp (&pattern,
1994 get_label_from_map (map,
1996 (JUMP_LABEL (insn))),
2004 try_constants (cc0_insn, map);
2007 try_constants (copy, map);
2009 /* Set the jump label of COPY correctly to avoid problems with
2010 later passes of unroll_loop, if INSN had jump label set. */
2011 if (JUMP_LABEL (insn))
2015 /* Can't use the label_map for every insn, since this may be
2016 the backward branch, and hence the label was not mapped. */
2017 if ((set = single_set (copy)))
2019 tem = SET_SRC (set);
2020 if (GET_CODE (tem) == LABEL_REF)
2021 label = XEXP (tem, 0);
2022 else if (GET_CODE (tem) == IF_THEN_ELSE)
2024 if (XEXP (tem, 1) != pc_rtx)
2025 label = XEXP (XEXP (tem, 1), 0);
2027 label = XEXP (XEXP (tem, 2), 0);
2031 if (label && GET_CODE (label) == CODE_LABEL)
2032 JUMP_LABEL (copy) = label;
2035 /* An unrecognizable jump insn, probably the entry jump
2036 for a switch statement. This label must have been mapped,
2037 so just use the label_map to get the new jump label. */
2039 = get_label_from_map (map,
2040 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2043 /* If this is a non-local jump, then must increase the label
2044 use count so that the label will not be deleted when the
2045 original jump is deleted. */
2046 LABEL_NUSES (JUMP_LABEL (copy))++;
2048 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2049 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2051 rtx pat = PATTERN (copy);
2052 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2053 int len = XVECLEN (pat, diff_vec_p);
2056 for (i = 0; i < len; i++)
2057 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2060 /* If this used to be a conditional jump insn but whose branch
2061 direction is now known, we must do something special. */
2062 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2065 /* The previous insn set cc0 for us. So delete it. */
2066 delete_insn (PREV_INSN (copy));
2069 /* If this is now a no-op, delete it. */
2070 if (map->last_pc_value == pc_rtx)
2072 /* Don't let delete_insn delete the label referenced here,
2073 because we might possibly need it later for some other
2074 instruction in the loop. */
2075 if (JUMP_LABEL (copy))
2076 LABEL_NUSES (JUMP_LABEL (copy))++;
2078 if (JUMP_LABEL (copy))
2079 LABEL_NUSES (JUMP_LABEL (copy))--;
2083 /* Otherwise, this is unconditional jump so we must put a
2084 BARRIER after it. We could do some dead code elimination
2085 here, but jump.c will do it just as well. */
2091 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
2092 copy = emit_call_insn (pattern);
2093 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2095 /* Because the USAGE information potentially contains objects other
2096 than hard registers, we need to copy it. */
2097 CALL_INSN_FUNCTION_USAGE (copy)
2098 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn), map);
2102 try_constants (cc0_insn, map);
2105 try_constants (copy, map);
2107 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2108 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2109 map->const_equiv_map[i] = 0;
2113 /* If this is the loop start label, then we don't need to emit a
2114 copy of this label since no one will use it. */
2116 if (insn != start_label)
2118 copy = emit_label (get_label_from_map (map,
2119 CODE_LABEL_NUMBER (insn)));
2125 copy = emit_barrier ();
2129 /* VTOP notes are valid only before the loop exit test. If placed
2130 anywhere else, loop may generate bad code. */
2132 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2133 && (NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2134 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2135 copy = emit_note (NOTE_SOURCE_FILE (insn),
2136 NOTE_LINE_NUMBER (insn));
2146 map->insn_map[INSN_UID (insn)] = copy;
2148 while (insn != copy_end);
2150 /* Now finish coping the REG_NOTES. */
2154 insn = NEXT_INSN (insn);
2155 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2156 || GET_CODE (insn) == CALL_INSN)
2157 && map->insn_map[INSN_UID (insn)])
2158 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2160 while (insn != copy_end);
2162 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2163 each of these notes here, since there may be some important ones, such as
2164 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2165 iteration, because the original notes won't be deleted.
2167 We can't use insert_before here, because when from preconditioning,
2168 insert_before points before the loop. We can't use copy_end, because
2169 there may be insns already inserted after it (which we don't want to
2170 copy) when not from preconditioning code. */
2172 if (! last_iteration)
2174 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2176 if (GET_CODE (insn) == NOTE
2177 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED)
2178 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2182 if (final_label && LABEL_NUSES (final_label) > 0)
2183 emit_label (final_label);
2185 tem = gen_sequence ();
2187 emit_insn_before (tem, insert_before);
2190 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2191 emitted. This will correctly handle the case where the increment value
2192 won't fit in the immediate field of a PLUS insns. */
2195 emit_unrolled_add (dest_reg, src_reg, increment)
2196 rtx dest_reg, src_reg, increment;
2200 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2201 dest_reg, 0, OPTAB_LIB_WIDEN);
2203 if (dest_reg != result)
2204 emit_move_insn (dest_reg, result);
2207 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2208 is a backward branch in that range that branches to somewhere between
2209 LOOP_START and INSN. Returns 0 otherwise. */
2211 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2212 In practice, this is not a problem, because this function is seldom called,
2213 and uses a negligible amount of CPU time on average. */
2216 back_branch_in_range_p (insn, loop_start, loop_end)
2218 rtx loop_start, loop_end;
2220 rtx p, q, target_insn;
2221 rtx orig_loop_end = loop_end;
2223 /* Stop before we get to the backward branch at the end of the loop. */
2224 loop_end = prev_nonnote_insn (loop_end);
2225 if (GET_CODE (loop_end) == BARRIER)
2226 loop_end = PREV_INSN (loop_end);
2228 /* Check in case insn has been deleted, search forward for first non
2229 deleted insn following it. */
2230 while (INSN_DELETED_P (insn))
2231 insn = NEXT_INSN (insn);
2233 /* Check for the case where insn is the last insn in the loop. Deal
2234 with the case where INSN was a deleted loop test insn, in which case
2235 it will now be the NOTE_LOOP_END. */
2236 if (insn == loop_end || insn == orig_loop_end)
2239 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2241 if (GET_CODE (p) == JUMP_INSN)
2243 target_insn = JUMP_LABEL (p);
2245 /* Search from loop_start to insn, to see if one of them is
2246 the target_insn. We can't use INSN_LUID comparisons here,
2247 since insn may not have an LUID entry. */
2248 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2249 if (q == target_insn)
2257 /* Try to generate the simplest rtx for the expression
2258 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2262 fold_rtx_mult_add (mult1, mult2, add1, mode)
2263 rtx mult1, mult2, add1;
2264 enum machine_mode mode;
2269 /* The modes must all be the same. This should always be true. For now,
2270 check to make sure. */
2271 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2272 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2273 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2276 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2277 will be a constant. */
2278 if (GET_CODE (mult1) == CONST_INT)
2285 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2287 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2289 /* Again, put the constant second. */
2290 if (GET_CODE (add1) == CONST_INT)
2297 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2299 result = gen_rtx_PLUS (mode, add1, mult_res);
2304 /* Searches the list of induction struct's for the biv BL, to try to calculate
2305 the total increment value for one iteration of the loop as a constant.
2307 Returns the increment value as an rtx, simplified as much as possible,
2308 if it can be calculated. Otherwise, returns 0. */
2311 biv_total_increment (bl, loop_start, loop_end)
2312 struct iv_class *bl;
2313 rtx loop_start, loop_end;
2315 struct induction *v;
2318 /* For increment, must check every instruction that sets it. Each
2319 instruction must be executed only once each time through the loop.
2320 To verify this, we check that the insn is always executed, and that
2321 there are no backward branches after the insn that branch to before it.
2322 Also, the insn must have a mult_val of one (to make sure it really is
2325 result = const0_rtx;
2326 for (v = bl->biv; v; v = v->next_iv)
2328 if (v->always_computable && v->mult_val == const1_rtx
2329 && ! v->maybe_multiple)
2330 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2338 /* Determine the initial value of the iteration variable, and the amount
2339 that it is incremented each loop. Use the tables constructed by
2340 the strength reduction pass to calculate these values.
2342 Initial_value and/or increment are set to zero if their values could not
2346 iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
2347 rtx iteration_var, *initial_value, *increment;
2348 rtx loop_start, loop_end;
2350 struct iv_class *bl;
2352 struct induction *v;
2355 /* Clear the result values, in case no answer can be found. */
2359 /* The iteration variable can be either a giv or a biv. Check to see
2360 which it is, and compute the variable's initial value, and increment
2361 value if possible. */
2363 /* If this is a new register, can't handle it since we don't have any
2364 reg_iv_type entry for it. */
2365 if ((unsigned) REGNO (iteration_var) > reg_iv_type->num_elements)
2367 if (loop_dump_stream)
2368 fprintf (loop_dump_stream,
2369 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2373 /* Reject iteration variables larger than the host wide int size, since they
2374 could result in a number of iterations greater than the range of our
2375 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2376 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2377 > HOST_BITS_PER_WIDE_INT))
2379 if (loop_dump_stream)
2380 fprintf (loop_dump_stream,
2381 "Loop unrolling: Iteration var rejected because mode too large.\n");
2384 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2386 if (loop_dump_stream)
2387 fprintf (loop_dump_stream,
2388 "Loop unrolling: Iteration var not an integer.\n");
2391 else if (REG_IV_TYPE (REGNO (iteration_var)) == BASIC_INDUCT)
2393 /* Grab initial value, only useful if it is a constant. */
2394 bl = reg_biv_class[REGNO (iteration_var)];
2395 *initial_value = bl->initial_value;
2397 *increment = biv_total_increment (bl, loop_start, loop_end);
2399 else if (REG_IV_TYPE (REGNO (iteration_var)) == GENERAL_INDUCT)
2402 /* ??? The code below does not work because the incorrect number of
2403 iterations is calculated when the biv is incremented after the giv
2404 is set (which is the usual case). This can probably be accounted
2405 for by biasing the initial_value by subtracting the amount of the
2406 increment that occurs between the giv set and the giv test. However,
2407 a giv as an iterator is very rare, so it does not seem worthwhile
2409 /* ??? An example failure is: i = 6; do {;} while (i++ < 9). */
2410 if (loop_dump_stream)
2411 fprintf (loop_dump_stream,
2412 "Loop unrolling: Giv iterators are not handled.\n");
2415 /* Initial value is mult_val times the biv's initial value plus
2416 add_val. Only useful if it is a constant. */
2417 v = REG_IV_INFO (REGNO (iteration_var));
2418 bl = reg_biv_class[REGNO (v->src_reg)];
2419 *initial_value = fold_rtx_mult_add (v->mult_val, bl->initial_value,
2420 v->add_val, v->mode);
2422 /* Increment value is mult_val times the increment value of the biv. */
2424 *increment = biv_total_increment (bl, loop_start, loop_end);
2426 *increment = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx,
2432 if (loop_dump_stream)
2433 fprintf (loop_dump_stream,
2434 "Loop unrolling: Not basic or general induction var.\n");
2440 /* For each biv and giv, determine whether it can be safely split into
2441 a different variable for each unrolled copy of the loop body. If it
2442 is safe to split, then indicate that by saving some useful info
2443 in the splittable_regs array.
2445 If the loop is being completely unrolled, then splittable_regs will hold
2446 the current value of the induction variable while the loop is unrolled.
2447 It must be set to the initial value of the induction variable here.
2448 Otherwise, splittable_regs will hold the difference between the current
2449 value of the induction variable and the value the induction variable had
2450 at the top of the loop. It must be set to the value 0 here.
2452 Returns the total number of instructions that set registers that are
2455 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2456 constant values are unnecessary, since we can easily calculate increment
2457 values in this case even if nothing is constant. The increment value
2458 should not involve a multiply however. */
2460 /* ?? Even if the biv/giv increment values aren't constant, it may still
2461 be beneficial to split the variable if the loop is only unrolled a few
2462 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2465 find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
2466 unroll_number, n_iterations)
2467 enum unroll_types unroll_type;
2468 rtx loop_start, loop_end;
2469 rtx end_insert_before;
2471 unsigned HOST_WIDE_INT n_iterations;
2473 struct iv_class *bl;
2474 struct induction *v;
2476 rtx biv_final_value;
2480 for (bl = loop_iv_list; bl; bl = bl->next)
2482 /* Biv_total_increment must return a constant value,
2483 otherwise we can not calculate the split values. */
2485 increment = biv_total_increment (bl, loop_start, loop_end);
2486 if (! increment || GET_CODE (increment) != CONST_INT)
2489 /* The loop must be unrolled completely, or else have a known number
2490 of iterations and only one exit, or else the biv must be dead
2491 outside the loop, or else the final value must be known. Otherwise,
2492 it is unsafe to split the biv since it may not have the proper
2493 value on loop exit. */
2495 /* loop_number_exit_count is non-zero if the loop has an exit other than
2496 a fall through at the end. */
2499 biv_final_value = 0;
2500 if (unroll_type != UNROLL_COMPLETELY
2501 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2502 || unroll_type == UNROLL_NAIVE)
2503 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2505 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2506 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2507 < INSN_LUID (bl->init_insn))
2508 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2509 && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end,
2513 /* If any of the insns setting the BIV don't do so with a simple
2514 PLUS, we don't know how to split it. */
2515 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2516 if ((tem = single_set (v->insn)) == 0
2517 || GET_CODE (SET_DEST (tem)) != REG
2518 || REGNO (SET_DEST (tem)) != bl->regno
2519 || GET_CODE (SET_SRC (tem)) != PLUS)
2522 /* If final value is non-zero, then must emit an instruction which sets
2523 the value of the biv to the proper value. This is done after
2524 handling all of the givs, since some of them may need to use the
2525 biv's value in their initialization code. */
2527 /* This biv is splittable. If completely unrolling the loop, save
2528 the biv's initial value. Otherwise, save the constant zero. */
2530 if (biv_splittable == 1)
2532 if (unroll_type == UNROLL_COMPLETELY)
2534 /* If the initial value of the biv is itself (i.e. it is too
2535 complicated for strength_reduce to compute), or is a hard
2536 register, or it isn't invariant, then we must create a new
2537 pseudo reg to hold the initial value of the biv. */
2539 if (GET_CODE (bl->initial_value) == REG
2540 && (REGNO (bl->initial_value) == bl->regno
2541 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2542 || ! invariant_p (bl->initial_value)))
2544 rtx tem = gen_reg_rtx (bl->biv->mode);
2546 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2547 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2550 if (loop_dump_stream)
2551 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2552 bl->regno, REGNO (tem));
2554 splittable_regs[bl->regno] = tem;
2557 splittable_regs[bl->regno] = bl->initial_value;
2560 splittable_regs[bl->regno] = const0_rtx;
2562 /* Save the number of instructions that modify the biv, so that
2563 we can treat the last one specially. */
2565 splittable_regs_updates[bl->regno] = bl->biv_count;
2566 result += bl->biv_count;
2568 if (loop_dump_stream)
2569 fprintf (loop_dump_stream,
2570 "Biv %d safe to split.\n", bl->regno);
2573 /* Check every giv that depends on this biv to see whether it is
2574 splittable also. Even if the biv isn't splittable, givs which
2575 depend on it may be splittable if the biv is live outside the
2576 loop, and the givs aren't. */
2578 result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
2579 increment, unroll_number);
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. */
2585 if (biv_final_value)
2587 /* If the loop has multiple exits, emit the insns before the
2588 loop to ensure that it will always be executed no matter
2589 how the loop exits. Otherwise emit the insn after the loop,
2590 since this is slightly more efficient. */
2591 if (! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
2592 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2597 /* Create a new register to hold the value of the biv, and then
2598 set the biv to its final value before the loop start. The biv
2599 is set to its final value before loop start to ensure that
2600 this insn will always be executed, no matter how the loop
2602 rtx tem = gen_reg_rtx (bl->biv->mode);
2603 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2605 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2607 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2611 if (loop_dump_stream)
2612 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2613 REGNO (bl->biv->src_reg), REGNO (tem));
2615 /* Set up the mapping from the original biv register to the new
2617 bl->biv->src_reg = tem;
2624 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2625 for the instruction that is using it. Do not make any changes to that
2629 verify_addresses (v, giv_inc, unroll_number)
2630 struct induction *v;
2635 rtx orig_addr = *v->location;
2636 rtx last_addr = plus_constant (v->dest_reg,
2637 INTVAL (giv_inc) * (unroll_number - 1));
2639 /* First check to see if either address would fail. Handle the fact
2640 that we have may have a match_dup. */
2641 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2642 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2645 /* Now put things back the way they were before. This should always
2647 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2653 /* For every giv based on the biv BL, check to determine whether it is
2654 splittable. This is a subroutine to find_splittable_regs ().
2656 Return the number of instructions that set splittable registers. */
2659 find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
2661 struct iv_class *bl;
2662 enum unroll_types unroll_type;
2663 rtx loop_start, loop_end;
2667 struct induction *v, *v2;
2672 /* Scan the list of givs, and set the same_insn field when there are
2673 multiple identical givs in the same insn. */
2674 for (v = bl->giv; v; v = v->next_iv)
2675 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2676 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2680 for (v = bl->giv; v; v = v->next_iv)
2684 /* Only split the giv if it has already been reduced, or if the loop is
2685 being completely unrolled. */
2686 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2689 /* The giv can be split if the insn that sets the giv is executed once
2690 and only once on every iteration of the loop. */
2691 /* An address giv can always be split. v->insn is just a use not a set,
2692 and hence it does not matter whether it is always executed. All that
2693 matters is that all the biv increments are always executed, and we
2694 won't reach here if they aren't. */
2695 if (v->giv_type != DEST_ADDR
2696 && (! v->always_computable
2697 || back_branch_in_range_p (v->insn, loop_start, loop_end)))
2700 /* The giv increment value must be a constant. */
2701 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2703 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2706 /* The loop must be unrolled completely, or else have a known number of
2707 iterations and only one exit, or else the giv must be dead outside
2708 the loop, or else the final value of the giv must be known.
2709 Otherwise, it is not safe to split the giv since it may not have the
2710 proper value on loop exit. */
2712 /* The used outside loop test will fail for DEST_ADDR givs. They are
2713 never used outside the loop anyways, so it is always safe to split a
2717 if (unroll_type != UNROLL_COMPLETELY
2718 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2719 || unroll_type == UNROLL_NAIVE)
2720 && v->giv_type != DEST_ADDR
2721 /* The next part is true if the pseudo is used outside the loop.
2722 We assume that this is true for any pseudo created after loop
2723 starts, because we don't have a reg_n_info entry for them. */
2724 && (REGNO (v->dest_reg) >= max_reg_before_loop
2725 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2726 /* Check for the case where the pseudo is set by a shift/add
2727 sequence, in which case the first insn setting the pseudo
2728 is the first insn of the shift/add sequence. */
2729 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2730 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2731 != INSN_UID (XEXP (tem, 0)))))
2732 /* Line above always fails if INSN was moved by loop opt. */
2733 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2734 >= INSN_LUID (loop_end)))
2735 /* Givs made from biv increments are missed by the above test, so
2736 test explicitly for them. */
2737 && (REGNO (v->dest_reg) < first_increment_giv
2738 || REGNO (v->dest_reg) > last_increment_giv)
2739 && ! (final_value = v->final_value))
2743 /* Currently, non-reduced/final-value givs are never split. */
2744 /* Should emit insns after the loop if possible, as the biv final value
2747 /* If the final value is non-zero, and the giv has not been reduced,
2748 then must emit an instruction to set the final value. */
2749 if (final_value && !v->new_reg)
2751 /* Create a new register to hold the value of the giv, and then set
2752 the giv to its final value before the loop start. The giv is set
2753 to its final value before loop start to ensure that this insn
2754 will always be executed, no matter how we exit. */
2755 tem = gen_reg_rtx (v->mode);
2756 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2757 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2760 if (loop_dump_stream)
2761 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2762 REGNO (v->dest_reg), REGNO (tem));
2768 /* This giv is splittable. If completely unrolling the loop, save the
2769 giv's initial value. Otherwise, save the constant zero for it. */
2771 if (unroll_type == UNROLL_COMPLETELY)
2773 /* It is not safe to use bl->initial_value here, because it may not
2774 be invariant. It is safe to use the initial value stored in
2775 the splittable_regs array if it is set. In rare cases, it won't
2776 be set, so then we do exactly the same thing as
2777 find_splittable_regs does to get a safe value. */
2778 rtx biv_initial_value;
2780 if (splittable_regs[bl->regno])
2781 biv_initial_value = splittable_regs[bl->regno];
2782 else if (GET_CODE (bl->initial_value) != REG
2783 || (REGNO (bl->initial_value) != bl->regno
2784 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2785 biv_initial_value = bl->initial_value;
2788 rtx tem = gen_reg_rtx (bl->biv->mode);
2790 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2791 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2793 biv_initial_value = tem;
2795 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2796 v->add_val, v->mode);
2803 /* If a giv was combined with another giv, then we can only split
2804 this giv if the giv it was combined with was reduced. This
2805 is because the value of v->new_reg is meaningless in this
2807 if (v->same && ! v->same->new_reg)
2809 if (loop_dump_stream)
2810 fprintf (loop_dump_stream,
2811 "giv combined with unreduced giv not split.\n");
2814 /* If the giv is an address destination, it could be something other
2815 than a simple register, these have to be treated differently. */
2816 else if (v->giv_type == DEST_REG)
2818 /* If value is not a constant, register, or register plus
2819 constant, then compute its value into a register before
2820 loop start. This prevents invalid rtx sharing, and should
2821 generate better code. We can use bl->initial_value here
2822 instead of splittable_regs[bl->regno] because this code
2823 is going before the loop start. */
2824 if (unroll_type == UNROLL_COMPLETELY
2825 && GET_CODE (value) != CONST_INT
2826 && GET_CODE (value) != REG
2827 && (GET_CODE (value) != PLUS
2828 || GET_CODE (XEXP (value, 0)) != REG
2829 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2831 rtx tem = gen_reg_rtx (v->mode);
2832 record_base_value (REGNO (tem), v->add_val, 0);
2833 emit_iv_add_mult (bl->initial_value, v->mult_val,
2834 v->add_val, tem, loop_start);
2838 splittable_regs[REGNO (v->new_reg)] = value;
2839 derived_regs[REGNO (v->new_reg)] = v->derived;
2843 /* Splitting address givs is useful since it will often allow us
2844 to eliminate some increment insns for the base giv as
2847 /* If the addr giv is combined with a dest_reg giv, then all
2848 references to that dest reg will be remapped, which is NOT
2849 what we want for split addr regs. We always create a new
2850 register for the split addr giv, just to be safe. */
2852 /* If we have multiple identical address givs within a
2853 single instruction, then use a single pseudo reg for
2854 both. This is necessary in case one is a match_dup
2857 v->const_adjust = 0;
2861 v->dest_reg = v->same_insn->dest_reg;
2862 if (loop_dump_stream)
2863 fprintf (loop_dump_stream,
2864 "Sharing address givs in insn %d\n",
2865 INSN_UID (v->insn));
2867 /* If multiple address GIVs have been combined with the
2868 same dest_reg GIV, do not create a new register for
2870 else if (unroll_type != UNROLL_COMPLETELY
2871 && v->giv_type == DEST_ADDR
2872 && v->same && v->same->giv_type == DEST_ADDR
2873 && v->same->unrolled
2874 /* combine_givs_p may return true for some cases
2875 where the add and mult values are not equal.
2876 To share a register here, the values must be
2878 && rtx_equal_p (v->same->mult_val, v->mult_val)
2879 && rtx_equal_p (v->same->add_val, v->add_val)
2880 /* If the memory references have different modes,
2881 then the address may not be valid and we must
2882 not share registers. */
2883 && verify_addresses (v, giv_inc, unroll_number))
2885 v->dest_reg = v->same->dest_reg;
2888 else if (unroll_type != UNROLL_COMPLETELY)
2890 /* If not completely unrolling the loop, then create a new
2891 register to hold the split value of the DEST_ADDR giv.
2892 Emit insn to initialize its value before loop start. */
2894 rtx tem = gen_reg_rtx (v->mode);
2895 record_base_value (REGNO (tem), v->add_val, 0);
2897 /* If the address giv has a constant in its new_reg value,
2898 then this constant can be pulled out and put in value,
2899 instead of being part of the initialization code. */
2901 if (GET_CODE (v->new_reg) == PLUS
2902 && GET_CODE (XEXP (v->new_reg, 1)) == CONST_INT)
2905 = plus_constant (tem, INTVAL (XEXP (v->new_reg,1)));
2907 /* Only succeed if this will give valid addresses.
2908 Try to validate both the first and the last
2909 address resulting from loop unrolling, if
2910 one fails, then can't do const elim here. */
2911 if (verify_addresses (v, giv_inc, unroll_number))
2913 /* Save the negative of the eliminated const, so
2914 that we can calculate the dest_reg's increment
2916 v->const_adjust = - INTVAL (XEXP (v->new_reg, 1));
2918 v->new_reg = XEXP (v->new_reg, 0);
2919 if (loop_dump_stream)
2920 fprintf (loop_dump_stream,
2921 "Eliminating constant from giv %d\n",
2930 /* If the address hasn't been checked for validity yet, do so
2931 now, and fail completely if either the first or the last
2932 unrolled copy of the address is not a valid address
2933 for the instruction that uses it. */
2934 if (v->dest_reg == tem
2935 && ! verify_addresses (v, giv_inc, unroll_number))
2937 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2938 if (v2->same_insn == v)
2941 if (loop_dump_stream)
2942 fprintf (loop_dump_stream,
2943 "Invalid address for giv at insn %d\n",
2944 INSN_UID (v->insn));
2948 /* We set this after the address check, to guarantee that
2949 the register will be initialized. */
2952 /* To initialize the new register, just move the value of
2953 new_reg into it. This is not guaranteed to give a valid
2954 instruction on machines with complex addressing modes.
2955 If we can't recognize it, then delete it and emit insns
2956 to calculate the value from scratch. */
2957 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
2958 copy_rtx (v->new_reg)),
2960 if (recog_memoized (PREV_INSN (loop_start)) < 0)
2964 /* We can't use bl->initial_value to compute the initial
2965 value, because the loop may have been preconditioned.
2966 We must calculate it from NEW_REG. Try using
2967 force_operand instead of emit_iv_add_mult. */
2968 delete_insn (PREV_INSN (loop_start));
2971 ret = force_operand (v->new_reg, tem);
2973 emit_move_insn (tem, ret);
2974 sequence = gen_sequence ();
2976 emit_insn_before (sequence, loop_start);
2978 if (loop_dump_stream)
2979 fprintf (loop_dump_stream,
2980 "Invalid init insn, rewritten.\n");
2985 v->dest_reg = value;
2987 /* Check the resulting address for validity, and fail
2988 if the resulting address would be invalid. */
2989 if (! verify_addresses (v, giv_inc, unroll_number))
2991 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2992 if (v2->same_insn == v)
2995 if (loop_dump_stream)
2996 fprintf (loop_dump_stream,
2997 "Invalid address for giv at insn %d\n",
2998 INSN_UID (v->insn));
3003 /* Store the value of dest_reg into the insn. This sharing
3004 will not be a problem as this insn will always be copied
3007 *v->location = v->dest_reg;
3009 /* If this address giv is combined with a dest reg giv, then
3010 save the base giv's induction pointer so that we will be
3011 able to handle this address giv properly. The base giv
3012 itself does not have to be splittable. */
3014 if (v->same && v->same->giv_type == DEST_REG)
3015 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3017 if (GET_CODE (v->new_reg) == REG)
3019 /* This giv maybe hasn't been combined with any others.
3020 Make sure that it's giv is marked as splittable here. */
3022 splittable_regs[REGNO (v->new_reg)] = value;
3023 derived_regs[REGNO (v->new_reg)] = v->derived;
3025 /* Make it appear to depend upon itself, so that the
3026 giv will be properly split in the main loop above. */
3030 addr_combined_regs[REGNO (v->new_reg)] = v;
3034 if (loop_dump_stream)
3035 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3041 /* Currently, unreduced giv's can't be split. This is not too much
3042 of a problem since unreduced giv's are not live across loop
3043 iterations anyways. When unrolling a loop completely though,
3044 it makes sense to reduce&split givs when possible, as this will
3045 result in simpler instructions, and will not require that a reg
3046 be live across loop iterations. */
3048 splittable_regs[REGNO (v->dest_reg)] = value;
3049 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3050 REGNO (v->dest_reg), INSN_UID (v->insn));
3056 /* Unreduced givs are only updated once by definition. Reduced givs
3057 are updated as many times as their biv is. Mark it so if this is
3058 a splittable register. Don't need to do anything for address givs
3059 where this may not be a register. */
3061 if (GET_CODE (v->new_reg) == REG)
3065 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3067 splittable_regs_updates[REGNO (v->new_reg)] = count;
3072 if (loop_dump_stream)
3076 if (GET_CODE (v->dest_reg) == CONST_INT)
3078 else if (GET_CODE (v->dest_reg) != REG)
3079 regnum = REGNO (XEXP (v->dest_reg, 0));
3081 regnum = REGNO (v->dest_reg);
3082 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3083 regnum, INSN_UID (v->insn));
3090 /* Try to prove that the register is dead after the loop exits. Trace every
3091 loop exit looking for an insn that will always be executed, which sets
3092 the register to some value, and appears before the first use of the register
3093 is found. If successful, then return 1, otherwise return 0. */
3095 /* ?? Could be made more intelligent in the handling of jumps, so that
3096 it can search past if statements and other similar structures. */
3099 reg_dead_after_loop (reg, loop_start, loop_end)
3100 rtx reg, loop_start, loop_end;
3105 int label_count = 0;
3106 int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
3108 /* In addition to checking all exits of this loop, we must also check
3109 all exits of inner nested loops that would exit this loop. We don't
3110 have any way to identify those, so we just give up if there are any
3111 such inner loop exits. */
3113 for (label = loop_number_exit_labels[this_loop_num]; label;
3114 label = LABEL_NEXTREF (label))
3117 if (label_count != loop_number_exit_count[this_loop_num])
3120 /* HACK: Must also search the loop fall through exit, create a label_ref
3121 here which points to the loop_end, and append the loop_number_exit_labels
3123 label = gen_rtx_LABEL_REF (VOIDmode, loop_end);
3124 LABEL_NEXTREF (label) = loop_number_exit_labels[this_loop_num];
3126 for ( ; label; label = LABEL_NEXTREF (label))
3128 /* Succeed if find an insn which sets the biv or if reach end of
3129 function. Fail if find an insn that uses the biv, or if come to
3130 a conditional jump. */
3132 insn = NEXT_INSN (XEXP (label, 0));
3135 code = GET_CODE (insn);
3136 if (GET_RTX_CLASS (code) == 'i')
3140 if (reg_referenced_p (reg, PATTERN (insn)))
3143 set = single_set (insn);
3144 if (set && rtx_equal_p (SET_DEST (set), reg))
3148 if (code == JUMP_INSN)
3150 if (GET_CODE (PATTERN (insn)) == RETURN)
3152 else if (! simplejump_p (insn)
3153 /* Prevent infinite loop following infinite loops. */
3154 || jump_count++ > 20)
3157 insn = JUMP_LABEL (insn);
3160 insn = NEXT_INSN (insn);
3164 /* Success, the register is dead on all loop exits. */
3168 /* Try to calculate the final value of the biv, the value it will have at
3169 the end of the loop. If we can do it, return that value. */
3172 final_biv_value (bl, loop_start, loop_end, n_iterations)
3173 struct iv_class *bl;
3174 rtx loop_start, loop_end;
3175 unsigned HOST_WIDE_INT n_iterations;
3179 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3181 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3184 /* The final value for reversed bivs must be calculated differently than
3185 for ordinary bivs. In this case, there is already an insn after the
3186 loop which sets this biv's final value (if necessary), and there are
3187 no other loop exits, so we can return any value. */
3190 if (loop_dump_stream)
3191 fprintf (loop_dump_stream,
3192 "Final biv value for %d, reversed biv.\n", bl->regno);
3197 /* Try to calculate the final value as initial value + (number of iterations
3198 * increment). For this to work, increment must be invariant, the only
3199 exit from the loop must be the fall through at the bottom (otherwise
3200 it may not have its final value when the loop exits), and the initial
3201 value of the biv must be invariant. */
3203 if (n_iterations != 0
3204 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
3205 && invariant_p (bl->initial_value))
3207 increment = biv_total_increment (bl, loop_start, loop_end);
3209 if (increment && invariant_p (increment))
3211 /* Can calculate the loop exit value, emit insns after loop
3212 end to calculate this value into a temporary register in
3213 case it is needed later. */
3215 tem = gen_reg_rtx (bl->biv->mode);
3216 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3217 /* Make sure loop_end is not the last insn. */
3218 if (NEXT_INSN (loop_end) == 0)
3219 emit_note_after (NOTE_INSN_DELETED, loop_end);
3220 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3221 bl->initial_value, tem, NEXT_INSN (loop_end));
3223 if (loop_dump_stream)
3224 fprintf (loop_dump_stream,
3225 "Final biv value for %d, calculated.\n", bl->regno);
3231 /* Check to see if the biv is dead at all loop exits. */
3232 if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
3234 if (loop_dump_stream)
3235 fprintf (loop_dump_stream,
3236 "Final biv value for %d, biv dead after loop exit.\n",
3245 /* Try to calculate the final value of the giv, the value it will have at
3246 the end of the loop. If we can do it, return that value. */
3249 final_giv_value (v, loop_start, loop_end, n_iterations)
3250 struct induction *v;
3251 rtx loop_start, loop_end;
3252 unsigned HOST_WIDE_INT n_iterations;
3254 struct iv_class *bl;
3257 rtx insert_before, seq;
3259 bl = reg_biv_class[REGNO (v->src_reg)];
3261 /* The final value for givs which depend on reversed bivs must be calculated
3262 differently than for ordinary givs. In this case, there is already an
3263 insn after the loop which sets this giv's final value (if necessary),
3264 and there are no other loop exits, so we can return any value. */
3267 if (loop_dump_stream)
3268 fprintf (loop_dump_stream,
3269 "Final giv value for %d, depends on reversed biv\n",
3270 REGNO (v->dest_reg));
3274 /* Try to calculate the final value as a function of the biv it depends
3275 upon. The only exit from the loop must be the fall through at the bottom
3276 (otherwise it may not have its final value when the loop exits). */
3278 /* ??? Can calculate the final giv value by subtracting off the
3279 extra biv increments times the giv's mult_val. The loop must have
3280 only one exit for this to work, but the loop iterations does not need
3283 if (n_iterations != 0
3284 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
3286 /* ?? It is tempting to use the biv's value here since these insns will
3287 be put after the loop, and hence the biv will have its final value
3288 then. However, this fails if the biv is subsequently eliminated.
3289 Perhaps determine whether biv's are eliminable before trying to
3290 determine whether giv's are replaceable so that we can use the
3291 biv value here if it is not eliminable. */
3293 /* We are emitting code after the end of the loop, so we must make
3294 sure that bl->initial_value is still valid then. It will still
3295 be valid if it is invariant. */
3297 increment = biv_total_increment (bl, loop_start, loop_end);
3299 if (increment && invariant_p (increment)
3300 && invariant_p (bl->initial_value))
3302 /* Can calculate the loop exit value of its biv as
3303 (n_iterations * increment) + initial_value */
3305 /* The loop exit value of the giv is then
3306 (final_biv_value - extra increments) * mult_val + add_val.
3307 The extra increments are any increments to the biv which
3308 occur in the loop after the giv's value is calculated.
3309 We must search from the insn that sets the giv to the end
3310 of the loop to calculate this value. */
3312 insert_before = NEXT_INSN (loop_end);
3314 /* Put the final biv value in tem. */
3315 tem = gen_reg_rtx (bl->biv->mode);
3316 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3317 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3318 bl->initial_value, tem, insert_before);
3320 /* Subtract off extra increments as we find them. */
3321 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3322 insn = NEXT_INSN (insn))
3324 struct induction *biv;
3326 for (biv = bl->biv; biv; biv = biv->next_iv)
3327 if (biv->insn == insn)
3330 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3331 biv->add_val, NULL_RTX, 0,
3333 seq = gen_sequence ();
3335 emit_insn_before (seq, insert_before);
3339 /* Now calculate the giv's final value. */
3340 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3343 if (loop_dump_stream)
3344 fprintf (loop_dump_stream,
3345 "Final giv value for %d, calc from biv's value.\n",
3346 REGNO (v->dest_reg));
3352 /* Replaceable giv's should never reach here. */
3356 /* Check to see if the biv is dead at all loop exits. */
3357 if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
3359 if (loop_dump_stream)
3360 fprintf (loop_dump_stream,
3361 "Final giv value for %d, giv dead after loop exit.\n",
3362 REGNO (v->dest_reg));
3371 /* Look back before LOOP_START for then insn that sets REG and return
3372 the equivalent constant if there is a REG_EQUAL note otherwise just
3373 the SET_SRC of REG. */
3376 loop_find_equiv_value (loop_start, reg)
3384 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3386 if (GET_CODE (insn) == CODE_LABEL)
3389 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3390 && reg_set_p (reg, insn))
3392 /* We found the last insn before the loop that sets the register.
3393 If it sets the entire register, and has a REG_EQUAL note,
3394 then use the value of the REG_EQUAL note. */
3395 if ((set = single_set (insn))
3396 && (SET_DEST (set) == reg))
3398 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3400 /* Only use the REG_EQUAL note if it is a constant.
3401 Other things, divide in particular, will cause
3402 problems later if we use them. */
3403 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3404 && CONSTANT_P (XEXP (note, 0)))
3405 ret = XEXP (note, 0);
3407 ret = SET_SRC (set);
3416 /* Return a simplified rtx for the expression OP - REG.
3418 REG must appear in OP, and OP must be a register or the sum of a register
3421 Thus, the return value must be const0_rtx or the second term.
3423 The caller is responsible for verifying that REG appears in OP and OP has
3427 subtract_reg_term (op, reg)
3432 if (GET_CODE (op) == PLUS)
3434 if (XEXP (op, 0) == reg)
3435 return XEXP (op, 1);
3436 else if (XEXP (op, 1) == reg)
3437 return XEXP (op, 0);
3439 /* OP does not contain REG as a term. */
3444 /* Find and return register term common to both expressions OP0 and
3445 OP1 or NULL_RTX if no such term exists. Each expression must be a
3446 REG or a PLUS of a REG. */
3449 find_common_reg_term (op0, op1)
3452 if ((GET_CODE (op0) == REG || GET_CODE (op0) == PLUS)
3453 && (GET_CODE (op1) == REG || GET_CODE (op1) == PLUS))
3460 if (GET_CODE (op0) == PLUS)
3461 op01 = XEXP (op0, 1), op00 = XEXP (op0, 0);
3463 op01 = const0_rtx, op00 = op0;
3465 if (GET_CODE (op1) == PLUS)
3466 op11 = XEXP (op1, 1), op10 = XEXP (op1, 0);
3468 op11 = const0_rtx, op10 = op1;
3470 /* Find and return common register term if present. */
3471 if (REG_P (op00) && (op00 == op10 || op00 == op11))
3473 else if (REG_P (op01) && (op01 == op10 || op01 == op11))
3477 /* No common register term found. */
3482 /* Calculate the number of loop iterations. Returns the exact number of loop
3483 iterations if it can be calculated, otherwise returns zero. */
3485 unsigned HOST_WIDE_INT
3486 loop_iterations (loop_start, loop_end, loop_info)
3487 rtx loop_start, loop_end;
3488 struct loop_info *loop_info;
3490 rtx comparison, comparison_value;
3491 rtx iteration_var, initial_value, increment, final_value;
3492 enum rtx_code comparison_code;
3493 HOST_WIDE_INT abs_inc;
3494 unsigned HOST_WIDE_INT abs_diff;
3497 int unsigned_p, compare_dir, final_larger;
3502 loop_info->n_iterations = 0;
3503 loop_info->initial_value = 0;
3504 loop_info->initial_equiv_value = 0;
3505 loop_info->comparison_value = 0;
3506 loop_info->final_value = 0;
3507 loop_info->final_equiv_value = 0;
3508 loop_info->increment = 0;
3509 loop_info->iteration_var = 0;
3510 loop_info->unroll_number = 1;
3511 loop_info->vtop = 0;
3513 /* We used to use prev_nonnote_insn here, but that fails because it might
3514 accidentally get the branch for a contained loop if the branch for this
3515 loop was deleted. We can only trust branches immediately before the
3517 last_loop_insn = PREV_INSN (loop_end);
3519 /* ??? We should probably try harder to find the jump insn
3520 at the end of the loop. The following code assumes that
3521 the last loop insn is a jump to the top of the loop. */
3522 if (GET_CODE (last_loop_insn) != JUMP_INSN)
3524 if (loop_dump_stream)
3525 fprintf (loop_dump_stream,
3526 "Loop iterations: No final conditional branch found.\n");
3530 /* If there is a more than a single jump to the top of the loop
3531 we cannot (easily) determine the iteration count. */
3532 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
3534 if (loop_dump_stream)
3535 fprintf (loop_dump_stream,
3536 "Loop iterations: Loop has multiple back edges.\n");
3540 /* Find the iteration variable. If the last insn is a conditional
3541 branch, and the insn before tests a register value, make that the
3542 iteration variable. */
3544 comparison = get_condition_for_loop (last_loop_insn);
3545 if (comparison == 0)
3547 if (loop_dump_stream)
3548 fprintf (loop_dump_stream,
3549 "Loop iterations: No final comparison found.\n");
3553 /* ??? Get_condition may switch position of induction variable and
3554 invariant register when it canonicalizes the comparison. */
3556 comparison_code = GET_CODE (comparison);
3557 iteration_var = XEXP (comparison, 0);
3558 comparison_value = XEXP (comparison, 1);
3560 /* Check if there is a NOTE_INSN_LOOP_VTOP note. If there is,
3561 that means that this is a for or while style loop, with
3562 a loop exit test at the start. Thus, we can assume that
3563 the loop condition was true when the loop was entered.
3565 We start at the end and search backwards for the previous
3566 NOTE. If there is no NOTE_INSN_LOOP_VTOP for this loop,
3567 the search will stop at the NOTE_INSN_LOOP_CONT. */
3570 vtop = PREV_INSN (vtop);
3571 while (GET_CODE (vtop) != NOTE
3572 || NOTE_LINE_NUMBER (vtop) > 0
3573 || NOTE_LINE_NUMBER (vtop) == NOTE_REPEATED_LINE_NUMBER
3574 || NOTE_LINE_NUMBER (vtop) == NOTE_INSN_DELETED);
3575 if (NOTE_LINE_NUMBER (vtop) != NOTE_INSN_LOOP_VTOP)
3577 loop_info->vtop = vtop;
3579 if (GET_CODE (iteration_var) != REG)
3581 if (loop_dump_stream)
3582 fprintf (loop_dump_stream,
3583 "Loop iterations: Comparison not against register.\n");
3587 /* Loop iterations is always called before any new registers are created
3588 now, so this should never occur. */
3590 if (REGNO (iteration_var) >= max_reg_before_loop)
3593 iteration_info (iteration_var, &initial_value, &increment,
3594 loop_start, loop_end);
3595 if (initial_value == 0)
3596 /* iteration_info already printed a message. */
3601 switch (comparison_code)
3616 /* Cannot determine loop iterations with this case. */
3635 /* If the comparison value is an invariant register, then try to find
3636 its value from the insns before the start of the loop. */
3638 final_value = comparison_value;
3639 if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
3641 final_value = loop_find_equiv_value (loop_start, comparison_value);
3642 /* If we don't get an invariant final value, we are better
3643 off with the original register. */
3644 if (!invariant_p (final_value))
3645 final_value = comparison_value;
3648 /* Calculate the approximate final value of the induction variable
3649 (on the last successful iteration). The exact final value
3650 depends on the branch operator, and increment sign. It will be
3651 wrong if the iteration variable is not incremented by one each
3652 time through the loop and (comparison_value + off_by_one -
3653 initial_value) % increment != 0.
3654 ??? Note that the final_value may overflow and thus final_larger
3655 will be bogus. A potentially infinite loop will be classified
3656 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3658 final_value = plus_constant (final_value, off_by_one);
3660 /* Save the calculated values describing this loop's bounds, in case
3661 precondition_loop_p will need them later. These values can not be
3662 recalculated inside precondition_loop_p because strength reduction
3663 optimizations may obscure the loop's structure.
3665 These values are only required by precondition_loop_p and insert_bct
3666 whenever the number of iterations cannot be computed at compile time.
3667 Only the difference between final_value and initial_value is
3668 important. Note that final_value is only approximate. */
3669 loop_info->initial_value = initial_value;
3670 loop_info->comparison_value = comparison_value;
3671 loop_info->final_value = plus_constant (comparison_value, off_by_one);
3672 loop_info->increment = increment;
3673 loop_info->iteration_var = iteration_var;
3674 loop_info->comparison_code = comparison_code;
3676 /* Try to determine the iteration count for loops such
3677 as (for i = init; i < init + const; i++). When running the
3678 loop optimization twice, the first pass often converts simple
3679 loops into this form. */
3681 if (REG_P (initial_value))
3687 reg1 = initial_value;
3688 if (GET_CODE (final_value) == PLUS)
3689 reg2 = XEXP (final_value, 0), const2 = XEXP (final_value, 1);
3691 reg2 = final_value, const2 = const0_rtx;
3693 /* Check for initial_value = reg1, final_value = reg2 + const2,
3694 where reg1 != reg2. */
3695 if (REG_P (reg2) && reg2 != reg1)
3699 /* Find what reg1 is equivalent to. Hopefully it will
3700 either be reg2 or reg2 plus a constant. */
3701 temp = loop_find_equiv_value (loop_start, reg1);
3702 if (find_common_reg_term (temp, reg2))
3703 initial_value = temp;
3706 /* Find what reg2 is equivalent to. Hopefully it will
3707 either be reg1 or reg1 plus a constant. Let's ignore
3708 the latter case for now since it is not so common. */
3709 temp = loop_find_equiv_value (loop_start, reg2);
3710 if (temp == loop_info->iteration_var)
3711 temp = initial_value;
3713 final_value = (const2 == const0_rtx)
3714 ? reg1 : gen_rtx_PLUS (GET_MODE (reg1), reg1, const2);
3717 else if (loop_info->vtop && GET_CODE (reg2) == CONST_INT)
3721 /* When running the loop optimizer twice, check_dbra_loop
3722 further obfuscates reversible loops of the form:
3723 for (i = init; i < init + const; i++). We often end up with
3724 final_value = 0, initial_value = temp, temp = temp2 - init,
3725 where temp2 = init + const. If the loop has a vtop we
3726 can replace initial_value with const. */
3728 temp = loop_find_equiv_value (loop_start, reg1);
3729 if (GET_CODE (temp) == MINUS && REG_P (XEXP (temp, 0)))
3731 rtx temp2 = loop_find_equiv_value (loop_start, XEXP (temp, 0));
3732 if (GET_CODE (temp2) == PLUS
3733 && XEXP (temp2, 0) == XEXP (temp, 1))
3734 initial_value = XEXP (temp2, 1);
3739 /* If have initial_value = reg + const1 and final_value = reg +
3740 const2, then replace initial_value with const1 and final_value
3741 with const2. This should be safe since we are protected by the
3742 initial comparison before entering the loop if we have a vtop.
3743 For example, a + b < a + c is not equivalent to b < c for all a
3744 when using modulo arithmetic.
3746 ??? Without a vtop we could still perform the optimization if we check
3747 the initial and final values carefully. */
3749 && (reg_term = find_common_reg_term (initial_value, final_value)))
3751 initial_value = subtract_reg_term (initial_value, reg_term);
3752 final_value = subtract_reg_term (final_value, reg_term);
3755 loop_info->initial_equiv_value = initial_value;
3756 loop_info->final_equiv_value = final_value;
3760 if (loop_dump_stream)
3761 fprintf (loop_dump_stream,
3762 "Loop iterations: Increment value can't be calculated.\n");
3766 if (GET_CODE (increment) != CONST_INT)
3768 increment = loop_find_equiv_value (loop_start, increment);
3770 if (GET_CODE (increment) != CONST_INT)
3772 if (loop_dump_stream)
3774 fprintf (loop_dump_stream,
3775 "Loop iterations: Increment value not constant ");
3776 print_rtl (loop_dump_stream, increment);
3777 fprintf (loop_dump_stream, ".\n");
3781 loop_info->increment = increment;
3784 if (GET_CODE (initial_value) != CONST_INT)
3786 if (loop_dump_stream)
3788 fprintf (loop_dump_stream,
3789 "Loop iterations: Initial value not constant ");
3790 print_rtl (loop_dump_stream, initial_value);
3791 fprintf (loop_dump_stream, ".\n");
3795 else if (comparison_code == EQ)
3797 if (loop_dump_stream)
3798 fprintf (loop_dump_stream,
3799 "Loop iterations: EQ comparison loop.\n");
3802 else if (GET_CODE (final_value) != CONST_INT)
3804 if (loop_dump_stream)
3806 fprintf (loop_dump_stream,
3807 "Loop iterations: Final value not constant ");
3808 print_rtl (loop_dump_stream, final_value);
3809 fprintf (loop_dump_stream, ".\n");
3814 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3817 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3818 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3819 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3820 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3822 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3823 - (INTVAL (final_value) < INTVAL (initial_value));
3825 if (INTVAL (increment) > 0)
3827 else if (INTVAL (increment) == 0)
3832 /* There are 27 different cases: compare_dir = -1, 0, 1;
3833 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3834 There are 4 normal cases, 4 reverse cases (where the iteration variable
3835 will overflow before the loop exits), 4 infinite loop cases, and 15
3836 immediate exit (0 or 1 iteration depending on loop type) cases.
3837 Only try to optimize the normal cases. */
3839 /* (compare_dir/final_larger/increment_dir)
3840 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3841 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3842 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3843 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3845 /* ?? If the meaning of reverse loops (where the iteration variable
3846 will overflow before the loop exits) is undefined, then could
3847 eliminate all of these special checks, and just always assume
3848 the loops are normal/immediate/infinite. Note that this means
3849 the sign of increment_dir does not have to be known. Also,
3850 since it does not really hurt if immediate exit loops or infinite loops
3851 are optimized, then that case could be ignored also, and hence all
3852 loops can be optimized.
3854 According to ANSI Spec, the reverse loop case result is undefined,
3855 because the action on overflow is undefined.
3857 See also the special test for NE loops below. */
3859 if (final_larger == increment_dir && final_larger != 0
3860 && (final_larger == compare_dir || compare_dir == 0))
3865 if (loop_dump_stream)
3866 fprintf (loop_dump_stream,
3867 "Loop iterations: Not normal loop.\n");
3871 /* Calculate the number of iterations, final_value is only an approximation,
3872 so correct for that. Note that abs_diff and n_iterations are
3873 unsigned, because they can be as large as 2^n - 1. */
3875 abs_inc = INTVAL (increment);
3877 abs_diff = INTVAL (final_value) - INTVAL (initial_value);
3878 else if (abs_inc < 0)
3880 abs_diff = INTVAL (initial_value) - INTVAL (final_value);
3886 /* For NE tests, make sure that the iteration variable won't miss
3887 the final value. If abs_diff mod abs_incr is not zero, then the
3888 iteration variable will overflow before the loop exits, and we
3889 can not calculate the number of iterations. */
3890 if (compare_dir == 0 && (abs_diff % abs_inc) != 0)
3893 /* Note that the number of iterations could be calculated using
3894 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3895 handle potential overflow of the summation. */
3896 loop_info->n_iterations = abs_diff / abs_inc + ((abs_diff % abs_inc) != 0);
3897 return loop_info->n_iterations;
3901 /* Replace uses of split bivs with their split pseudo register. This is
3902 for original instructions which remain after loop unrolling without
3906 remap_split_bivs (x)
3909 register enum rtx_code code;
3916 code = GET_CODE (x);
3931 /* If non-reduced/final-value givs were split, then this would also
3932 have to remap those givs also. */
3934 if (REGNO (x) < max_reg_before_loop
3935 && REG_IV_TYPE (REGNO (x)) == BASIC_INDUCT)
3936 return reg_biv_class[REGNO (x)]->biv->src_reg;
3943 fmt = GET_RTX_FORMAT (code);
3944 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3947 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
3951 for (j = 0; j < XVECLEN (x, i); j++)
3952 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
3958 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3959 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3960 return 0. COPY_START is where we can start looking for the insns
3961 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3964 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3965 must dominate LAST_UID.
3967 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3968 may not dominate LAST_UID.
3970 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3971 must dominate LAST_UID. */
3974 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
3981 int passed_jump = 0;
3982 rtx p = NEXT_INSN (copy_start);
3984 while (INSN_UID (p) != first_uid)
3986 if (GET_CODE (p) == JUMP_INSN)
3988 /* Could not find FIRST_UID. */
3994 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
3995 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
3996 || ! dead_or_set_regno_p (p, regno))
3999 /* FIRST_UID is always executed. */
4000 if (passed_jump == 0)
4003 while (INSN_UID (p) != last_uid)
4005 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4006 can not be sure that FIRST_UID dominates LAST_UID. */
4007 if (GET_CODE (p) == CODE_LABEL)
4009 /* Could not find LAST_UID, but we reached the end of the loop, so
4011 else if (p == copy_end)
4016 /* FIRST_UID is always executed if LAST_UID is executed. */