1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 93, 94, 95, 97, 1998 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 then this will hold the number of instructions in the loop that modify
184 the induction variable. Used to ensure that only the last insn modifying
185 a split iv will update the original iv of the dest. */
187 static int *splittable_regs_updates;
189 /* Forward declarations. */
191 static void init_reg_map PROTO((struct inline_remap *, int));
192 static rtx calculate_giv_inc PROTO((rtx, rtx, int));
193 static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
194 static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
195 static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
196 enum unroll_types, rtx, rtx, rtx, rtx));
197 void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
198 static rtx approx_final_value PROTO((enum rtx_code, rtx, int *, int *));
199 static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int,
200 unsigned HOST_WIDE_INT));
201 static int find_splittable_givs PROTO((struct iv_class *, enum unroll_types,
202 rtx, rtx, rtx, int));
203 static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
204 static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
205 static int verify_addresses PROTO((struct induction *, rtx, int));
206 static rtx remap_split_bivs PROTO((rtx));
208 /* Try to unroll one loop and split induction variables in the loop.
210 The loop is described by the arguments LOOP_END, INSN_COUNT, and
211 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
212 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
213 indicates whether information generated in the strength reduction pass
216 This function is intended to be called from within `strength_reduce'
220 unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
221 loop_info, strength_reduce_p)
225 rtx end_insert_before;
226 struct loop_info *loop_info;
227 int strength_reduce_p;
230 int unroll_number = 1;
231 rtx copy_start, copy_end;
232 rtx insn, sequence, pattern, tem;
233 int max_labelno, max_insnno;
235 struct inline_remap *map;
243 int splitting_not_safe = 0;
244 enum unroll_types unroll_type;
245 int loop_preconditioned = 0;
247 /* This points to the last real insn in the loop, which should be either
248 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
252 /* Don't bother unrolling huge loops. Since the minimum factor is
253 two, loops greater than one half of MAX_UNROLLED_INSNS will never
255 if (insn_count > MAX_UNROLLED_INSNS / 2)
257 if (loop_dump_stream)
258 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
262 /* When emitting debugger info, we can't unroll loops with unequal numbers
263 of block_beg and block_end notes, because that would unbalance the block
264 structure of the function. This can happen as a result of the
265 "if (foo) bar; else break;" optimization in jump.c. */
266 /* ??? Gcc has a general policy that -g is never supposed to change the code
267 that the compiler emits, so we must disable this optimization always,
268 even if debug info is not being output. This is rare, so this should
269 not be a significant performance problem. */
271 if (1 /* write_symbols != NO_DEBUG */)
273 int block_begins = 0;
276 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
278 if (GET_CODE (insn) == NOTE)
280 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
282 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
287 if (block_begins != block_ends)
289 if (loop_dump_stream)
290 fprintf (loop_dump_stream,
291 "Unrolling failure: Unbalanced block notes.\n");
296 /* Determine type of unroll to perform. Depends on the number of iterations
297 and the size of the loop. */
299 /* If there is no strength reduce info, then set
300 loop_info->n_iterations to zero. This can happen if
301 strength_reduce can't find any bivs in the loop. A value of zero
302 indicates that the number of iterations could not be calculated. */
304 if (! strength_reduce_p)
305 loop_info->n_iterations = 0;
307 if (loop_dump_stream && loop_info->n_iterations > 0)
309 fputs ("Loop unrolling: ", loop_dump_stream);
310 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
311 loop_info->n_iterations);
312 fputs (" iterations.\n", loop_dump_stream);
315 /* Find and save a pointer to the last nonnote insn in the loop. */
317 last_loop_insn = prev_nonnote_insn (loop_end);
319 /* Calculate how many times to unroll the loop. Indicate whether or
320 not the loop is being completely unrolled. */
322 if (loop_info->n_iterations == 1)
324 /* If number of iterations is exactly 1, then eliminate the compare and
325 branch at the end of the loop since they will never be taken.
326 Then return, since no other action is needed here. */
328 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
329 don't do anything. */
331 if (GET_CODE (last_loop_insn) == BARRIER)
333 /* Delete the jump insn. This will delete the barrier also. */
334 delete_insn (PREV_INSN (last_loop_insn));
336 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
339 /* The immediately preceding insn is a compare which must be
341 delete_insn (last_loop_insn);
342 delete_insn (PREV_INSN (last_loop_insn));
344 /* The immediately preceding insn may not be the compare, so don't
346 delete_insn (last_loop_insn);
351 else if (loop_info->n_iterations > 0
352 && loop_info->n_iterations * insn_count < MAX_UNROLLED_INSNS)
354 unroll_number = loop_info->n_iterations;
355 unroll_type = UNROLL_COMPLETELY;
357 else if (loop_info->n_iterations > 0)
359 /* Try to factor the number of iterations. Don't bother with the
360 general case, only using 2, 3, 5, and 7 will get 75% of all
361 numbers theoretically, and almost all in practice. */
363 for (i = 0; i < NUM_FACTORS; i++)
364 factors[i].count = 0;
366 temp = loop_info->n_iterations;
367 for (i = NUM_FACTORS - 1; i >= 0; i--)
368 while (temp % factors[i].factor == 0)
371 temp = temp / factors[i].factor;
374 /* Start with the larger factors first so that we generally
375 get lots of unrolling. */
379 for (i = 3; i >= 0; i--)
380 while (factors[i].count--)
382 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
384 unroll_number *= factors[i].factor;
385 temp *= factors[i].factor;
391 /* If we couldn't find any factors, then unroll as in the normal
393 if (unroll_number == 1)
395 if (loop_dump_stream)
396 fprintf (loop_dump_stream,
397 "Loop unrolling: No factors found.\n");
400 unroll_type = UNROLL_MODULO;
404 /* Default case, calculate number of times to unroll loop based on its
406 if (unroll_number == 1)
408 if (8 * insn_count < MAX_UNROLLED_INSNS)
410 else if (4 * insn_count < MAX_UNROLLED_INSNS)
415 unroll_type = UNROLL_NAIVE;
418 /* Now we know how many times to unroll the loop. */
420 if (loop_dump_stream)
421 fprintf (loop_dump_stream,
422 "Unrolling loop %d times.\n", unroll_number);
425 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
427 /* Loops of these types can start with jump down to the exit condition
428 in rare circumstances.
430 Consider a pair of nested loops where the inner loop is part
431 of the exit code for the outer loop.
433 In this case jump.c will not duplicate the exit test for the outer
434 loop, so it will start with a jump to the exit code.
436 Then consider if the inner loop turns out to iterate once and
437 only once. We will end up deleting the jumps associated with
438 the inner loop. However, the loop notes are not removed from
439 the instruction stream.
441 And finally assume that we can compute the number of iterations
444 In this case unroll may want to unroll the outer loop even though
445 it starts with a jump to the outer loop's exit code.
447 We could try to optimize this case, but it hardly seems worth it.
448 Just return without unrolling the loop in such cases. */
451 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
452 insn = NEXT_INSN (insn);
453 if (GET_CODE (insn) == JUMP_INSN)
457 if (unroll_type == UNROLL_COMPLETELY)
459 /* Completely unrolling the loop: Delete the compare and branch at
460 the end (the last two instructions). This delete must done at the
461 very end of loop unrolling, to avoid problems with calls to
462 back_branch_in_range_p, which is called by find_splittable_regs.
463 All increments of splittable bivs/givs are changed to load constant
466 copy_start = loop_start;
468 /* Set insert_before to the instruction immediately after the JUMP_INSN
469 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
470 the loop will be correctly handled by copy_loop_body. */
471 insert_before = NEXT_INSN (last_loop_insn);
473 /* Set copy_end to the insn before the jump at the end of the loop. */
474 if (GET_CODE (last_loop_insn) == BARRIER)
475 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
476 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
479 /* The instruction immediately before the JUMP_INSN is a compare
480 instruction which we do not want to copy. */
481 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
483 /* The instruction immediately before the JUMP_INSN may not be the
484 compare, so we must copy it. */
485 copy_end = PREV_INSN (last_loop_insn);
490 /* We currently can't unroll a loop if it doesn't end with a
491 JUMP_INSN. There would need to be a mechanism that recognizes
492 this case, and then inserts a jump after each loop body, which
493 jumps to after the last loop body. */
494 if (loop_dump_stream)
495 fprintf (loop_dump_stream,
496 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
500 else if (unroll_type == UNROLL_MODULO)
502 /* Partially unrolling the loop: The compare and branch at the end
503 (the last two instructions) must remain. Don't copy the compare
504 and branch instructions at the end of the loop. Insert the unrolled
505 code immediately before the compare/branch at the end so that the
506 code will fall through to them as before. */
508 copy_start = loop_start;
510 /* Set insert_before to the jump insn at the end of the loop.
511 Set copy_end to before the jump insn at the end of the loop. */
512 if (GET_CODE (last_loop_insn) == BARRIER)
514 insert_before = PREV_INSN (last_loop_insn);
515 copy_end = PREV_INSN (insert_before);
517 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
520 /* The instruction immediately before the JUMP_INSN is a compare
521 instruction which we do not want to copy or delete. */
522 insert_before = PREV_INSN (last_loop_insn);
523 copy_end = PREV_INSN (insert_before);
525 /* The instruction immediately before the JUMP_INSN may not be the
526 compare, so we must copy it. */
527 insert_before = last_loop_insn;
528 copy_end = PREV_INSN (last_loop_insn);
533 /* We currently can't unroll a loop if it doesn't end with a
534 JUMP_INSN. There would need to be a mechanism that recognizes
535 this case, and then inserts a jump after each loop body, which
536 jumps to after the last loop body. */
537 if (loop_dump_stream)
538 fprintf (loop_dump_stream,
539 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
545 /* Normal case: Must copy the compare and branch instructions at the
548 if (GET_CODE (last_loop_insn) == BARRIER)
550 /* Loop ends with an unconditional jump and a barrier.
551 Handle this like above, don't copy jump and barrier.
552 This is not strictly necessary, but doing so prevents generating
553 unconditional jumps to an immediately following label.
555 This will be corrected below if the target of this jump is
556 not the start_label. */
558 insert_before = PREV_INSN (last_loop_insn);
559 copy_end = PREV_INSN (insert_before);
561 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
563 /* Set insert_before to immediately after the JUMP_INSN, so that
564 NOTEs at the end of the loop will be correctly handled by
566 insert_before = NEXT_INSN (last_loop_insn);
567 copy_end = last_loop_insn;
571 /* We currently can't unroll a loop if it doesn't end with a
572 JUMP_INSN. There would need to be a mechanism that recognizes
573 this case, and then inserts a jump after each loop body, which
574 jumps to after the last loop body. */
575 if (loop_dump_stream)
576 fprintf (loop_dump_stream,
577 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
581 /* If copying exit test branches because they can not be eliminated,
582 then must convert the fall through case of the branch to a jump past
583 the end of the loop. Create a label to emit after the loop and save
584 it for later use. Do not use the label after the loop, if any, since
585 it might be used by insns outside the loop, or there might be insns
586 added before it later by final_[bg]iv_value which must be after
587 the real exit label. */
588 exit_label = gen_label_rtx ();
591 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
592 insn = NEXT_INSN (insn);
594 if (GET_CODE (insn) == JUMP_INSN)
596 /* The loop starts with a jump down to the exit condition test.
597 Start copying the loop after the barrier following this
599 copy_start = NEXT_INSN (insn);
601 /* Splitting induction variables doesn't work when the loop is
602 entered via a jump to the bottom, because then we end up doing
603 a comparison against a new register for a split variable, but
604 we did not execute the set insn for the new register because
605 it was skipped over. */
606 splitting_not_safe = 1;
607 if (loop_dump_stream)
608 fprintf (loop_dump_stream,
609 "Splitting not safe, because loop not entered at top.\n");
612 copy_start = loop_start;
615 /* This should always be the first label in the loop. */
616 start_label = NEXT_INSN (copy_start);
617 /* There may be a line number note and/or a loop continue note here. */
618 while (GET_CODE (start_label) == NOTE)
619 start_label = NEXT_INSN (start_label);
620 if (GET_CODE (start_label) != CODE_LABEL)
622 /* This can happen as a result of jump threading. If the first insns in
623 the loop test the same condition as the loop's backward jump, or the
624 opposite condition, then the backward jump will be modified to point
625 to elsewhere, and the loop's start label is deleted.
627 This case currently can not be handled by the loop unrolling code. */
629 if (loop_dump_stream)
630 fprintf (loop_dump_stream,
631 "Unrolling failure: unknown insns between BEG note and loop label.\n");
634 if (LABEL_NAME (start_label))
636 /* The jump optimization pass must have combined the original start label
637 with a named label for a goto. We can't unroll this case because
638 jumps which go to the named label must be handled differently than
639 jumps to the loop start, and it is impossible to differentiate them
641 if (loop_dump_stream)
642 fprintf (loop_dump_stream,
643 "Unrolling failure: loop start label is gone\n");
647 if (unroll_type == UNROLL_NAIVE
648 && GET_CODE (last_loop_insn) == BARRIER
649 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
651 /* In this case, we must copy the jump and barrier, because they will
652 not be converted to jumps to an immediately following label. */
654 insert_before = NEXT_INSN (last_loop_insn);
655 copy_end = last_loop_insn;
658 if (unroll_type == UNROLL_NAIVE
659 && GET_CODE (last_loop_insn) == JUMP_INSN
660 && start_label != JUMP_LABEL (last_loop_insn))
662 /* ??? The loop ends with a conditional branch that does not branch back
663 to the loop start label. In this case, we must emit an unconditional
664 branch to the loop exit after emitting the final branch.
665 copy_loop_body does not have support for this currently, so we
666 give up. It doesn't seem worthwhile to unroll anyways since
667 unrolling would increase the number of branch instructions
669 if (loop_dump_stream)
670 fprintf (loop_dump_stream,
671 "Unrolling failure: final conditional branch not to loop start\n");
675 /* Allocate a translation table for the labels and insn numbers.
676 They will be filled in as we copy the insns in the loop. */
678 max_labelno = max_label_num ();
679 max_insnno = get_max_uid ();
681 map = (struct inline_remap *) alloca (sizeof (struct inline_remap));
683 map->integrating = 0;
685 /* Allocate the label map. */
689 map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx));
691 local_label = (char *) alloca (max_labelno);
692 bzero (local_label, max_labelno);
697 /* Search the loop and mark all local labels, i.e. the ones which have to
698 be distinct labels when copied. For all labels which might be
699 non-local, set their label_map entries to point to themselves.
700 If they happen to be local their label_map entries will be overwritten
701 before the loop body is copied. The label_map entries for local labels
702 will be set to a different value each time the loop body is copied. */
704 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
708 if (GET_CODE (insn) == CODE_LABEL)
709 local_label[CODE_LABEL_NUMBER (insn)] = 1;
710 else if (GET_CODE (insn) == JUMP_INSN)
712 if (JUMP_LABEL (insn))
713 set_label_in_map (map,
714 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
716 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
717 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
719 rtx pat = PATTERN (insn);
720 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
721 int len = XVECLEN (pat, diff_vec_p);
724 for (i = 0; i < len; i++)
726 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
727 set_label_in_map (map,
728 CODE_LABEL_NUMBER (label),
733 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)))
734 set_label_in_map (map, CODE_LABEL_NUMBER (XEXP (note, 0)),
738 /* Allocate space for the insn map. */
740 map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx));
742 /* Set this to zero, to indicate that we are doing loop unrolling,
743 not function inlining. */
744 map->inline_target = 0;
746 /* The register and constant maps depend on the number of registers
747 present, so the final maps can't be created until after
748 find_splittable_regs is called. However, they are needed for
749 preconditioning, so we create temporary maps when preconditioning
752 /* The preconditioning code may allocate two new pseudo registers. */
753 maxregnum = max_reg_num ();
755 /* Allocate and zero out the splittable_regs and addr_combined_regs
756 arrays. These must be zeroed here because they will be used if
757 loop preconditioning is performed, and must be zero for that case.
759 It is safe to do this here, since the extra registers created by the
760 preconditioning code and find_splittable_regs will never be used
761 to access the splittable_regs[] and addr_combined_regs[] arrays. */
763 splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx));
764 bzero ((char *) splittable_regs, maxregnum * sizeof (rtx));
765 splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int));
766 bzero ((char *) splittable_regs_updates, maxregnum * sizeof (int));
768 = (struct induction **) alloca (maxregnum * sizeof (struct induction *));
769 bzero ((char *) addr_combined_regs, maxregnum * sizeof (struct induction *));
770 /* We must limit it to max_reg_before_loop, because only these pseudo
771 registers have valid regno_first_uid info. Any register created after
772 that is unlikely to be local to the loop anyways. */
773 local_regno = (char *) alloca (max_reg_before_loop);
774 bzero (local_regno, max_reg_before_loop);
776 /* Mark all local registers, i.e. the ones which are referenced only
778 if (INSN_UID (copy_end) < max_uid_for_loop)
780 int copy_start_luid = INSN_LUID (copy_start);
781 int copy_end_luid = INSN_LUID (copy_end);
783 /* If a register is used in the jump insn, we must not duplicate it
784 since it will also be used outside the loop. */
785 if (GET_CODE (copy_end) == JUMP_INSN)
787 /* If copy_start points to the NOTE that starts the loop, then we must
788 use the next luid, because invariant pseudo-regs moved out of the loop
789 have their lifetimes modified to start here, but they are not safe
791 if (copy_start == loop_start)
794 /* If a pseudo's lifetime is entirely contained within this loop, then we
795 can use a different pseudo in each unrolled copy of the loop. This
796 results in better code. */
797 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
798 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
799 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
800 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
801 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
803 /* However, we must also check for loop-carried dependencies.
804 If the value the pseudo has at the end of iteration X is
805 used by iteration X+1, then we can not use a different pseudo
806 for each unrolled copy of the loop. */
807 /* A pseudo is safe if regno_first_uid is a set, and this
808 set dominates all instructions from regno_first_uid to
810 /* ??? This check is simplistic. We would get better code if
811 this check was more sophisticated. */
812 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
813 copy_start, copy_end))
816 if (loop_dump_stream)
819 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
821 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
827 /* If this loop requires exit tests when unrolled, check to see if we
828 can precondition the loop so as to make the exit tests unnecessary.
829 Just like variable splitting, this is not safe if the loop is entered
830 via a jump to the bottom. Also, can not do this if no strength
831 reduce info, because precondition_loop_p uses this info. */
833 /* Must copy the loop body for preconditioning before the following
834 find_splittable_regs call since that will emit insns which need to
835 be after the preconditioned loop copies, but immediately before the
836 unrolled loop copies. */
838 /* Also, it is not safe to split induction variables for the preconditioned
839 copies of the loop body. If we split induction variables, then the code
840 assumes that each induction variable can be represented as a function
841 of its initial value and the loop iteration number. This is not true
842 in this case, because the last preconditioned copy of the loop body
843 could be any iteration from the first up to the `unroll_number-1'th,
844 depending on the initial value of the iteration variable. Therefore
845 we can not split induction variables here, because we can not calculate
846 their value. Hence, this code must occur before find_splittable_regs
849 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
851 rtx initial_value, final_value, increment;
853 if (precondition_loop_p (loop_start, loop_info,
854 &initial_value, &final_value, &increment))
857 enum machine_mode mode;
859 int abs_inc, neg_inc;
861 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
863 map->const_equiv_map = (rtx *) alloca (maxregnum * sizeof (rtx));
864 map->const_age_map = (unsigned *) alloca (maxregnum
865 * sizeof (unsigned));
866 map->const_equiv_map_size = maxregnum;
867 global_const_equiv_map = map->const_equiv_map;
868 global_const_equiv_map_size = maxregnum;
870 init_reg_map (map, maxregnum);
872 /* Limit loop unrolling to 4, since this will make 7 copies of
874 if (unroll_number > 4)
877 /* Save the absolute value of the increment, and also whether or
878 not it is negative. */
880 abs_inc = INTVAL (increment);
889 /* Decide what mode to do these calculations in. Choose the larger
890 of final_value's mode and initial_value's mode, or a full-word if
891 both are constants. */
892 mode = GET_MODE (final_value);
893 if (mode == VOIDmode)
895 mode = GET_MODE (initial_value);
896 if (mode == VOIDmode)
899 else if (mode != GET_MODE (initial_value)
900 && (GET_MODE_SIZE (mode)
901 < GET_MODE_SIZE (GET_MODE (initial_value))))
902 mode = GET_MODE (initial_value);
904 /* Calculate the difference between the final and initial values.
905 Final value may be a (plus (reg x) (const_int 1)) rtx.
906 Let the following cse pass simplify this if initial value is
909 We must copy the final and initial values here to avoid
910 improperly shared rtl. */
912 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
913 copy_rtx (initial_value), NULL_RTX, 0,
916 /* Now calculate (diff % (unroll * abs (increment))) by using an
918 diff = expand_binop (GET_MODE (diff), and_optab, diff,
919 GEN_INT (unroll_number * abs_inc - 1),
920 NULL_RTX, 0, OPTAB_LIB_WIDEN);
922 /* Now emit a sequence of branches to jump to the proper precond
925 labels = (rtx *) alloca (sizeof (rtx) * unroll_number);
926 for (i = 0; i < unroll_number; i++)
927 labels[i] = gen_label_rtx ();
929 /* Check for the case where the initial value is greater than or
930 equal to the final value. In that case, we want to execute
931 exactly one loop iteration. The code below will fail for this
932 case. This check does not apply if the loop has a NE
933 comparison at the end. */
935 if (loop_info->comparison_code != NE)
937 emit_cmp_insn (initial_value, final_value, neg_inc ? LE : GE,
938 NULL_RTX, mode, 0, 0);
940 emit_jump_insn (gen_ble (labels[1]));
942 emit_jump_insn (gen_bge (labels[1]));
943 JUMP_LABEL (get_last_insn ()) = labels[1];
944 LABEL_NUSES (labels[1])++;
947 /* Assuming the unroll_number is 4, and the increment is 2, then
948 for a negative increment: for a positive increment:
949 diff = 0,1 precond 0 diff = 0,7 precond 0
950 diff = 2,3 precond 3 diff = 1,2 precond 1
951 diff = 4,5 precond 2 diff = 3,4 precond 2
952 diff = 6,7 precond 1 diff = 5,6 precond 3 */
954 /* We only need to emit (unroll_number - 1) branches here, the
955 last case just falls through to the following code. */
957 /* ??? This would give better code if we emitted a tree of branches
958 instead of the current linear list of branches. */
960 for (i = 0; i < unroll_number - 1; i++)
963 enum rtx_code cmp_code;
965 /* For negative increments, must invert the constant compared
966 against, except when comparing against zero. */
974 cmp_const = unroll_number - i;
983 emit_cmp_insn (diff, GEN_INT (abs_inc * cmp_const),
984 cmp_code, NULL_RTX, mode, 0, 0);
987 emit_jump_insn (gen_beq (labels[i]));
989 emit_jump_insn (gen_bge (labels[i]));
991 emit_jump_insn (gen_ble (labels[i]));
992 JUMP_LABEL (get_last_insn ()) = labels[i];
993 LABEL_NUSES (labels[i])++;
996 /* If the increment is greater than one, then we need another branch,
997 to handle other cases equivalent to 0. */
999 /* ??? This should be merged into the code above somehow to help
1000 simplify the code here, and reduce the number of branches emitted.
1001 For the negative increment case, the branch here could easily
1002 be merged with the `0' case branch above. For the positive
1003 increment case, it is not clear how this can be simplified. */
1008 enum rtx_code cmp_code;
1012 cmp_const = abs_inc - 1;
1017 cmp_const = abs_inc * (unroll_number - 1) + 1;
1021 emit_cmp_insn (diff, GEN_INT (cmp_const), cmp_code, NULL_RTX,
1025 emit_jump_insn (gen_ble (labels[0]));
1027 emit_jump_insn (gen_bge (labels[0]));
1028 JUMP_LABEL (get_last_insn ()) = labels[0];
1029 LABEL_NUSES (labels[0])++;
1032 sequence = gen_sequence ();
1034 emit_insn_before (sequence, loop_start);
1036 /* Only the last copy of the loop body here needs the exit
1037 test, so set copy_end to exclude the compare/branch here,
1038 and then reset it inside the loop when get to the last
1041 if (GET_CODE (last_loop_insn) == BARRIER)
1042 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1043 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1046 /* The immediately preceding insn is a compare which we do not
1048 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1050 /* The immediately preceding insn may not be a compare, so we
1052 copy_end = PREV_INSN (last_loop_insn);
1058 for (i = 1; i < unroll_number; i++)
1060 emit_label_after (labels[unroll_number - i],
1061 PREV_INSN (loop_start));
1063 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1064 bzero ((char *) map->const_equiv_map, maxregnum * sizeof (rtx));
1065 bzero ((char *) map->const_age_map,
1066 maxregnum * sizeof (unsigned));
1069 for (j = 0; j < max_labelno; j++)
1071 set_label_in_map (map, j, gen_label_rtx ());
1073 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; j++)
1076 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1077 record_base_value (REGNO (map->reg_map[j]),
1078 regno_reg_rtx[j], 0);
1080 /* The last copy needs the compare/branch insns at the end,
1081 so reset copy_end here if the loop ends with a conditional
1084 if (i == unroll_number - 1)
1086 if (GET_CODE (last_loop_insn) == BARRIER)
1087 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1089 copy_end = last_loop_insn;
1092 /* None of the copies are the `last_iteration', so just
1093 pass zero for that parameter. */
1094 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1095 unroll_type, start_label, loop_end,
1096 loop_start, copy_end);
1098 emit_label_after (labels[0], PREV_INSN (loop_start));
1100 if (GET_CODE (last_loop_insn) == BARRIER)
1102 insert_before = PREV_INSN (last_loop_insn);
1103 copy_end = PREV_INSN (insert_before);
1108 /* The immediately preceding insn is a compare which we do not
1110 insert_before = PREV_INSN (last_loop_insn);
1111 copy_end = PREV_INSN (insert_before);
1113 /* The immediately preceding insn may not be a compare, so we
1115 insert_before = last_loop_insn;
1116 copy_end = PREV_INSN (last_loop_insn);
1120 /* Set unroll type to MODULO now. */
1121 unroll_type = UNROLL_MODULO;
1122 loop_preconditioned = 1;
1126 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1127 the loop unless all loops are being unrolled. */
1128 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1130 if (loop_dump_stream)
1131 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1135 /* At this point, we are guaranteed to unroll the loop. */
1137 /* Keep track of the unroll factor for the loop. */
1138 if (unroll_type == UNROLL_COMPLETELY)
1139 loop_info->unroll_number = -1;
1141 loop_info->unroll_number = unroll_number;
1144 /* For each biv and giv, determine whether it can be safely split into
1145 a different variable for each unrolled copy of the loop body.
1146 We precalculate and save this info here, since computing it is
1149 Do this before deleting any instructions from the loop, so that
1150 back_branch_in_range_p will work correctly. */
1152 if (splitting_not_safe)
1155 temp = find_splittable_regs (unroll_type, loop_start, loop_end,
1156 end_insert_before, unroll_number,
1157 loop_info->n_iterations);
1159 /* find_splittable_regs may have created some new registers, so must
1160 reallocate the reg_map with the new larger size, and must realloc
1161 the constant maps also. */
1163 maxregnum = max_reg_num ();
1164 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
1166 init_reg_map (map, maxregnum);
1168 /* Space is needed in some of the map for new registers, so new_maxregnum
1169 is an (over)estimate of how many registers will exist at the end. */
1170 new_maxregnum = maxregnum + (temp * unroll_number * 2);
1172 /* Must realloc space for the constant maps, because the number of registers
1173 may have changed. */
1175 map->const_equiv_map = (rtx *) alloca (new_maxregnum * sizeof (rtx));
1176 map->const_age_map = (unsigned *) alloca (new_maxregnum * sizeof (unsigned));
1178 map->const_equiv_map_size = new_maxregnum;
1179 global_const_equiv_map = map->const_equiv_map;
1180 global_const_equiv_map_size = new_maxregnum;
1182 /* Search the list of bivs and givs to find ones which need to be remapped
1183 when split, and set their reg_map entry appropriately. */
1185 for (bl = loop_iv_list; bl; bl = bl->next)
1187 if (REGNO (bl->biv->src_reg) != bl->regno)
1188 map->reg_map[bl->regno] = bl->biv->src_reg;
1190 /* Currently, non-reduced/final-value givs are never split. */
1191 for (v = bl->giv; v; v = v->next_iv)
1192 if (REGNO (v->src_reg) != bl->regno)
1193 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1197 /* Use our current register alignment and pointer flags. */
1198 map->regno_pointer_flag = regno_pointer_flag;
1199 map->regno_pointer_align = regno_pointer_align;
1201 /* If the loop is being partially unrolled, and the iteration variables
1202 are being split, and are being renamed for the split, then must fix up
1203 the compare/jump instruction at the end of the loop to refer to the new
1204 registers. This compare isn't copied, so the registers used in it
1205 will never be replaced if it isn't done here. */
1207 if (unroll_type == UNROLL_MODULO)
1209 insn = NEXT_INSN (copy_end);
1210 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1211 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1214 /* For unroll_number - 1 times, make a copy of each instruction
1215 between copy_start and copy_end, and insert these new instructions
1216 before the end of the loop. */
1218 for (i = 0; i < unroll_number; i++)
1220 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1221 bzero ((char *) map->const_equiv_map, new_maxregnum * sizeof (rtx));
1222 bzero ((char *) map->const_age_map, new_maxregnum * sizeof (unsigned));
1225 for (j = 0; j < max_labelno; j++)
1227 set_label_in_map (map, j, gen_label_rtx ());
1229 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; j++)
1232 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1233 record_base_value (REGNO (map->reg_map[j]),
1234 regno_reg_rtx[j], 0);
1237 /* If loop starts with a branch to the test, then fix it so that
1238 it points to the test of the first unrolled copy of the loop. */
1239 if (i == 0 && loop_start != copy_start)
1241 insn = PREV_INSN (copy_start);
1242 pattern = PATTERN (insn);
1244 tem = get_label_from_map (map,
1246 (XEXP (SET_SRC (pattern), 0)));
1247 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1249 /* Set the jump label so that it can be used by later loop unrolling
1251 JUMP_LABEL (insn) = tem;
1252 LABEL_NUSES (tem)++;
1255 copy_loop_body (copy_start, copy_end, map, exit_label,
1256 i == unroll_number - 1, unroll_type, start_label,
1257 loop_end, insert_before, insert_before);
1260 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1261 insn to be deleted. This prevents any runaway delete_insn call from
1262 more insns that it should, as it always stops at a CODE_LABEL. */
1264 /* Delete the compare and branch at the end of the loop if completely
1265 unrolling the loop. Deleting the backward branch at the end also
1266 deletes the code label at the start of the loop. This is done at
1267 the very end to avoid problems with back_branch_in_range_p. */
1269 if (unroll_type == UNROLL_COMPLETELY)
1270 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1272 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1274 /* Delete all of the original loop instructions. Don't delete the
1275 LOOP_BEG note, or the first code label in the loop. */
1277 insn = NEXT_INSN (copy_start);
1278 while (insn != safety_label)
1280 if (insn != start_label)
1281 insn = delete_insn (insn);
1283 insn = NEXT_INSN (insn);
1286 /* Can now delete the 'safety' label emitted to protect us from runaway
1287 delete_insn calls. */
1288 if (INSN_DELETED_P (safety_label))
1290 delete_insn (safety_label);
1292 /* If exit_label exists, emit it after the loop. Doing the emit here
1293 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1294 This is needed so that mostly_true_jump in reorg.c will treat jumps
1295 to this loop end label correctly, i.e. predict that they are usually
1298 emit_label_after (exit_label, loop_end);
1301 /* Return true if the loop can be safely, and profitably, preconditioned
1302 so that the unrolled copies of the loop body don't need exit tests.
1304 This only works if final_value, initial_value and increment can be
1305 determined, and if increment is a constant power of 2.
1306 If increment is not a power of 2, then the preconditioning modulo
1307 operation would require a real modulo instead of a boolean AND, and this
1308 is not considered `profitable'. */
1310 /* ??? If the loop is known to be executed very many times, or the machine
1311 has a very cheap divide instruction, then preconditioning is a win even
1312 when the increment is not a power of 2. Use RTX_COST to compute
1313 whether divide is cheap. */
1316 precondition_loop_p (loop_start, loop_info,
1317 initial_value, final_value, increment)
1319 struct loop_info *loop_info;
1320 rtx *initial_value, *final_value, *increment;
1323 if (loop_info->n_iterations > 0)
1325 *initial_value = const0_rtx;
1326 *increment = const1_rtx;
1327 *final_value = GEN_INT (loop_info->n_iterations);
1329 if (loop_dump_stream)
1331 fputs ("Preconditioning: Success, number of iterations known, ",
1333 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
1334 loop_info->n_iterations);
1335 fputs (".\n", loop_dump_stream);
1340 if (loop_info->initial_value == 0)
1342 if (loop_dump_stream)
1343 fprintf (loop_dump_stream,
1344 "Preconditioning: Could not find initial value.\n");
1347 else if (loop_info->increment == 0)
1349 if (loop_dump_stream)
1350 fprintf (loop_dump_stream,
1351 "Preconditioning: Could not find increment value.\n");
1354 else if (GET_CODE (loop_info->increment) != CONST_INT)
1356 if (loop_dump_stream)
1357 fprintf (loop_dump_stream,
1358 "Preconditioning: Increment not a constant.\n");
1361 else if ((exact_log2 (INTVAL (loop_info->increment)) < 0)
1362 && (exact_log2 (- INTVAL (loop_info->increment)) < 0))
1364 if (loop_dump_stream)
1365 fprintf (loop_dump_stream,
1366 "Preconditioning: Increment not a constant power of 2.\n");
1370 /* Unsigned_compare and compare_dir can be ignored here, since they do
1371 not matter for preconditioning. */
1373 if (loop_info->final_value == 0)
1375 if (loop_dump_stream)
1376 fprintf (loop_dump_stream,
1377 "Preconditioning: EQ comparison loop.\n");
1381 /* Must ensure that final_value is invariant, so call invariant_p to
1382 check. Before doing so, must check regno against max_reg_before_loop
1383 to make sure that the register is in the range covered by invariant_p.
1384 If it isn't, then it is most likely a biv/giv which by definition are
1386 if ((GET_CODE (loop_info->final_value) == REG
1387 && REGNO (loop_info->final_value) >= max_reg_before_loop)
1388 || (GET_CODE (loop_info->final_value) == PLUS
1389 && REGNO (XEXP (loop_info->final_value, 0)) >= max_reg_before_loop)
1390 || ! invariant_p (loop_info->final_value))
1392 if (loop_dump_stream)
1393 fprintf (loop_dump_stream,
1394 "Preconditioning: Final value not invariant.\n");
1398 /* Fail for floating point values, since the caller of this function
1399 does not have code to deal with them. */
1400 if (GET_MODE_CLASS (GET_MODE (loop_info->final_value)) == MODE_FLOAT
1401 || GET_MODE_CLASS (GET_MODE (loop_info->initial_value)) == MODE_FLOAT)
1403 if (loop_dump_stream)
1404 fprintf (loop_dump_stream,
1405 "Preconditioning: Floating point final or initial value.\n");
1409 /* Fail if loop_info->iteration_var is not live before loop_start,
1410 since we need to test its value in the preconditioning code. */
1412 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_info->iteration_var))]
1413 > INSN_LUID (loop_start))
1415 if (loop_dump_stream)
1416 fprintf (loop_dump_stream,
1417 "Preconditioning: Iteration var not live before loop start.\n");
1421 /* ??? Note that if iteration_info is modifed to allow GIV iterators
1422 such as "while (i-- > 0)", the initial value will be one too small.
1423 In this case, loop_iteration_var could be used to determine
1424 the correct initial value, provided the loop has not been reversed.
1426 Also note that the absolute values of initial_value and
1427 final_value are unimportant as only their difference is used for
1428 calculating the number of loop iterations. */
1429 *initial_value = loop_info->initial_value;
1430 *increment = loop_info->increment;
1431 *final_value = loop_info->final_value;
1434 if (loop_dump_stream)
1435 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1440 /* All pseudo-registers must be mapped to themselves. Two hard registers
1441 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1442 REGNUM, to avoid function-inlining specific conversions of these
1443 registers. All other hard regs can not be mapped because they may be
1448 init_reg_map (map, maxregnum)
1449 struct inline_remap *map;
1454 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1455 map->reg_map[i] = regno_reg_rtx[i];
1456 /* Just clear the rest of the entries. */
1457 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1458 map->reg_map[i] = 0;
1460 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1461 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1462 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1463 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1466 /* Strength-reduction will often emit code for optimized biv/givs which
1467 calculates their value in a temporary register, and then copies the result
1468 to the iv. This procedure reconstructs the pattern computing the iv;
1469 verifying that all operands are of the proper form.
1471 PATTERN must be the result of single_set.
1472 The return value is the amount that the giv is incremented by. */
1475 calculate_giv_inc (pattern, src_insn, regno)
1476 rtx pattern, src_insn;
1480 rtx increment_total = 0;
1484 /* Verify that we have an increment insn here. First check for a plus
1485 as the set source. */
1486 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1488 /* SR sometimes computes the new giv value in a temp, then copies it
1490 src_insn = PREV_INSN (src_insn);
1491 pattern = PATTERN (src_insn);
1492 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1495 /* The last insn emitted is not needed, so delete it to avoid confusing
1496 the second cse pass. This insn sets the giv unnecessarily. */
1497 delete_insn (get_last_insn ());
1500 /* Verify that we have a constant as the second operand of the plus. */
1501 increment = XEXP (SET_SRC (pattern), 1);
1502 if (GET_CODE (increment) != CONST_INT)
1504 /* SR sometimes puts the constant in a register, especially if it is
1505 too big to be an add immed operand. */
1506 src_insn = PREV_INSN (src_insn);
1507 increment = SET_SRC (PATTERN (src_insn));
1509 /* SR may have used LO_SUM to compute the constant if it is too large
1510 for a load immed operand. In this case, the constant is in operand
1511 one of the LO_SUM rtx. */
1512 if (GET_CODE (increment) == LO_SUM)
1513 increment = XEXP (increment, 1);
1515 /* Some ports store large constants in memory and add a REG_EQUAL
1516 note to the store insn. */
1517 else if (GET_CODE (increment) == MEM)
1519 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1521 increment = XEXP (note, 0);
1524 else if (GET_CODE (increment) == IOR
1525 || GET_CODE (increment) == ASHIFT
1526 || GET_CODE (increment) == PLUS)
1528 /* The rs6000 port loads some constants with IOR.
1529 The alpha port loads some constants with ASHIFT and PLUS. */
1530 rtx second_part = XEXP (increment, 1);
1531 enum rtx_code code = GET_CODE (increment);
1533 src_insn = PREV_INSN (src_insn);
1534 increment = SET_SRC (PATTERN (src_insn));
1535 /* Don't need the last insn anymore. */
1536 delete_insn (get_last_insn ());
1538 if (GET_CODE (second_part) != CONST_INT
1539 || GET_CODE (increment) != CONST_INT)
1543 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1544 else if (code == PLUS)
1545 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1547 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1550 if (GET_CODE (increment) != CONST_INT)
1553 /* The insn loading the constant into a register is no longer needed,
1555 delete_insn (get_last_insn ());
1558 if (increment_total)
1559 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1561 increment_total = increment;
1563 /* Check that the source register is the same as the register we expected
1564 to see as the source. If not, something is seriously wrong. */
1565 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1566 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1568 /* Some machines (e.g. the romp), may emit two add instructions for
1569 certain constants, so lets try looking for another add immediately
1570 before this one if we have only seen one add insn so far. */
1576 src_insn = PREV_INSN (src_insn);
1577 pattern = PATTERN (src_insn);
1579 delete_insn (get_last_insn ());
1587 return increment_total;
1590 /* Copy REG_NOTES, except for insn references, because not all insn_map
1591 entries are valid yet. We do need to copy registers now though, because
1592 the reg_map entries can change during copying. */
1595 initial_reg_note_copy (notes, map)
1597 struct inline_remap *map;
1604 copy = rtx_alloc (GET_CODE (notes));
1605 PUT_MODE (copy, GET_MODE (notes));
1607 if (GET_CODE (notes) == EXPR_LIST)
1608 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map);
1609 else if (GET_CODE (notes) == INSN_LIST)
1610 /* Don't substitute for these yet. */
1611 XEXP (copy, 0) = XEXP (notes, 0);
1615 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1620 /* Fixup insn references in copied REG_NOTES. */
1623 final_reg_note_copy (notes, map)
1625 struct inline_remap *map;
1629 for (note = notes; note; note = XEXP (note, 1))
1630 if (GET_CODE (note) == INSN_LIST)
1631 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1634 /* Copy each instruction in the loop, substituting from map as appropriate.
1635 This is very similar to a loop in expand_inline_function. */
1638 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1639 unroll_type, start_label, loop_end, insert_before,
1641 rtx copy_start, copy_end;
1642 struct inline_remap *map;
1645 enum unroll_types unroll_type;
1646 rtx start_label, loop_end, insert_before, copy_notes_from;
1650 int dest_reg_was_split, i;
1654 rtx final_label = 0;
1655 rtx giv_inc, giv_dest_reg, giv_src_reg;
1657 /* If this isn't the last iteration, then map any references to the
1658 start_label to final_label. Final label will then be emitted immediately
1659 after the end of this loop body if it was ever used.
1661 If this is the last iteration, then map references to the start_label
1663 if (! last_iteration)
1665 final_label = gen_label_rtx ();
1666 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1670 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1677 insn = NEXT_INSN (insn);
1679 map->orig_asm_operands_vector = 0;
1681 switch (GET_CODE (insn))
1684 pattern = PATTERN (insn);
1688 /* Check to see if this is a giv that has been combined with
1689 some split address givs. (Combined in the sense that
1690 `combine_givs' in loop.c has put two givs in the same register.)
1691 In this case, we must search all givs based on the same biv to
1692 find the address givs. Then split the address givs.
1693 Do this before splitting the giv, since that may map the
1694 SET_DEST to a new register. */
1696 if ((set = single_set (insn))
1697 && GET_CODE (SET_DEST (set)) == REG
1698 && addr_combined_regs[REGNO (SET_DEST (set))])
1700 struct iv_class *bl;
1701 struct induction *v, *tv;
1702 int regno = REGNO (SET_DEST (set));
1704 v = addr_combined_regs[REGNO (SET_DEST (set))];
1705 bl = reg_biv_class[REGNO (v->src_reg)];
1707 /* Although the giv_inc amount is not needed here, we must call
1708 calculate_giv_inc here since it might try to delete the
1709 last insn emitted. If we wait until later to call it,
1710 we might accidentally delete insns generated immediately
1711 below by emit_unrolled_add. */
1713 giv_inc = calculate_giv_inc (set, insn, regno);
1715 /* Now find all address giv's that were combined with this
1717 for (tv = bl->giv; tv; tv = tv->next_iv)
1718 if (tv->giv_type == DEST_ADDR && tv->same == v)
1722 /* If this DEST_ADDR giv was not split, then ignore it. */
1723 if (*tv->location != tv->dest_reg)
1726 /* Scale this_giv_inc if the multiplicative factors of
1727 the two givs are different. */
1728 this_giv_inc = INTVAL (giv_inc);
1729 if (tv->mult_val != v->mult_val)
1730 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1731 * INTVAL (tv->mult_val));
1733 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1734 *tv->location = tv->dest_reg;
1736 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1738 /* Must emit an insn to increment the split address
1739 giv. Add in the const_adjust field in case there
1740 was a constant eliminated from the address. */
1741 rtx value, dest_reg;
1743 /* tv->dest_reg will be either a bare register,
1744 or else a register plus a constant. */
1745 if (GET_CODE (tv->dest_reg) == REG)
1746 dest_reg = tv->dest_reg;
1748 dest_reg = XEXP (tv->dest_reg, 0);
1750 /* Check for shared address givs, and avoid
1751 incrementing the shared pseudo reg more than
1753 if (! tv->same_insn && ! tv->shared)
1755 /* tv->dest_reg may actually be a (PLUS (REG)
1756 (CONST)) here, so we must call plus_constant
1757 to add the const_adjust amount before calling
1758 emit_unrolled_add below. */
1759 value = plus_constant (tv->dest_reg,
1762 /* The constant could be too large for an add
1763 immediate, so can't directly emit an insn
1765 emit_unrolled_add (dest_reg, XEXP (value, 0),
1769 /* Reset the giv to be just the register again, in case
1770 it is used after the set we have just emitted.
1771 We must subtract the const_adjust factor added in
1773 tv->dest_reg = plus_constant (dest_reg,
1774 - tv->const_adjust);
1775 *tv->location = tv->dest_reg;
1780 /* If this is a setting of a splittable variable, then determine
1781 how to split the variable, create a new set based on this split,
1782 and set up the reg_map so that later uses of the variable will
1783 use the new split variable. */
1785 dest_reg_was_split = 0;
1787 if ((set = single_set (insn))
1788 && GET_CODE (SET_DEST (set)) == REG
1789 && splittable_regs[REGNO (SET_DEST (set))])
1791 int regno = REGNO (SET_DEST (set));
1793 dest_reg_was_split = 1;
1795 /* Compute the increment value for the giv, if it wasn't
1796 already computed above. */
1799 giv_inc = calculate_giv_inc (set, insn, regno);
1800 giv_dest_reg = SET_DEST (set);
1801 giv_src_reg = SET_DEST (set);
1803 if (unroll_type == UNROLL_COMPLETELY)
1805 /* Completely unrolling the loop. Set the induction
1806 variable to a known constant value. */
1808 /* The value in splittable_regs may be an invariant
1809 value, so we must use plus_constant here. */
1810 splittable_regs[regno]
1811 = plus_constant (splittable_regs[regno], INTVAL (giv_inc));
1813 if (GET_CODE (splittable_regs[regno]) == PLUS)
1815 giv_src_reg = XEXP (splittable_regs[regno], 0);
1816 giv_inc = XEXP (splittable_regs[regno], 1);
1820 /* The splittable_regs value must be a REG or a
1821 CONST_INT, so put the entire value in the giv_src_reg
1823 giv_src_reg = splittable_regs[regno];
1824 giv_inc = const0_rtx;
1829 /* Partially unrolling loop. Create a new pseudo
1830 register for the iteration variable, and set it to
1831 be a constant plus the original register. Except
1832 on the last iteration, when the result has to
1833 go back into the original iteration var register. */
1835 /* Handle bivs which must be mapped to a new register
1836 when split. This happens for bivs which need their
1837 final value set before loop entry. The new register
1838 for the biv was stored in the biv's first struct
1839 induction entry by find_splittable_regs. */
1841 if (regno < max_reg_before_loop
1842 && reg_iv_type[regno] == BASIC_INDUCT)
1844 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1845 giv_dest_reg = giv_src_reg;
1849 /* If non-reduced/final-value givs were split, then
1850 this would have to remap those givs also. See
1851 find_splittable_regs. */
1854 splittable_regs[regno]
1855 = GEN_INT (INTVAL (giv_inc)
1856 + INTVAL (splittable_regs[regno]));
1857 giv_inc = splittable_regs[regno];
1859 /* Now split the induction variable by changing the dest
1860 of this insn to a new register, and setting its
1861 reg_map entry to point to this new register.
1863 If this is the last iteration, and this is the last insn
1864 that will update the iv, then reuse the original dest,
1865 to ensure that the iv will have the proper value when
1866 the loop exits or repeats.
1868 Using splittable_regs_updates here like this is safe,
1869 because it can only be greater than one if all
1870 instructions modifying the iv are always executed in
1873 if (! last_iteration
1874 || (splittable_regs_updates[regno]-- != 1))
1876 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1878 map->reg_map[regno] = tem;
1879 record_base_value (REGNO (tem),
1880 giv_inc == const0_rtx
1882 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1883 giv_src_reg, giv_inc),
1887 map->reg_map[regno] = giv_src_reg;
1890 /* The constant being added could be too large for an add
1891 immediate, so can't directly emit an insn here. */
1892 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1893 copy = get_last_insn ();
1894 pattern = PATTERN (copy);
1898 pattern = copy_rtx_and_substitute (pattern, map);
1899 copy = emit_insn (pattern);
1901 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1904 /* If this insn is setting CC0, it may need to look at
1905 the insn that uses CC0 to see what type of insn it is.
1906 In that case, the call to recog via validate_change will
1907 fail. So don't substitute constants here. Instead,
1908 do it when we emit the following insn.
1910 For example, see the pyr.md file. That machine has signed and
1911 unsigned compares. The compare patterns must check the
1912 following branch insn to see which what kind of compare to
1915 If the previous insn set CC0, substitute constants on it as
1917 if (sets_cc0_p (PATTERN (copy)) != 0)
1922 try_constants (cc0_insn, map);
1924 try_constants (copy, map);
1927 try_constants (copy, map);
1930 /* Make split induction variable constants `permanent' since we
1931 know there are no backward branches across iteration variable
1932 settings which would invalidate this. */
1933 if (dest_reg_was_split)
1935 int regno = REGNO (SET_DEST (pattern));
1937 if (regno < map->const_equiv_map_size
1938 && map->const_age_map[regno] == map->const_age)
1939 map->const_age_map[regno] = -1;
1944 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
1945 copy = emit_jump_insn (pattern);
1946 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1948 if (JUMP_LABEL (insn) == start_label && insn == copy_end
1949 && ! last_iteration)
1951 /* This is a branch to the beginning of the loop; this is the
1952 last insn being copied; and this is not the last iteration.
1953 In this case, we want to change the original fall through
1954 case to be a branch past the end of the loop, and the
1955 original jump label case to fall_through. */
1957 if (invert_exp (pattern, copy))
1959 if (! redirect_exp (&pattern,
1960 get_label_from_map (map,
1962 (JUMP_LABEL (insn))),
1969 rtx lab = gen_label_rtx ();
1970 /* Can't do it by reversing the jump (probably because we
1971 couldn't reverse the conditions), so emit a new
1972 jump_insn after COPY, and redirect the jump around
1974 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
1975 jmp = emit_barrier_after (jmp);
1976 emit_label_after (lab, jmp);
1977 LABEL_NUSES (lab) = 0;
1978 if (! redirect_exp (&pattern,
1979 get_label_from_map (map,
1981 (JUMP_LABEL (insn))),
1989 try_constants (cc0_insn, map);
1992 try_constants (copy, map);
1994 /* Set the jump label of COPY correctly to avoid problems with
1995 later passes of unroll_loop, if INSN had jump label set. */
1996 if (JUMP_LABEL (insn))
2000 /* Can't use the label_map for every insn, since this may be
2001 the backward branch, and hence the label was not mapped. */
2002 if ((set = single_set (copy)))
2004 tem = SET_SRC (set);
2005 if (GET_CODE (tem) == LABEL_REF)
2006 label = XEXP (tem, 0);
2007 else if (GET_CODE (tem) == IF_THEN_ELSE)
2009 if (XEXP (tem, 1) != pc_rtx)
2010 label = XEXP (XEXP (tem, 1), 0);
2012 label = XEXP (XEXP (tem, 2), 0);
2016 if (label && GET_CODE (label) == CODE_LABEL)
2017 JUMP_LABEL (copy) = label;
2020 /* An unrecognizable jump insn, probably the entry jump
2021 for a switch statement. This label must have been mapped,
2022 so just use the label_map to get the new jump label. */
2024 = get_label_from_map (map,
2025 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2028 /* If this is a non-local jump, then must increase the label
2029 use count so that the label will not be deleted when the
2030 original jump is deleted. */
2031 LABEL_NUSES (JUMP_LABEL (copy))++;
2033 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2034 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2036 rtx pat = PATTERN (copy);
2037 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2038 int len = XVECLEN (pat, diff_vec_p);
2041 for (i = 0; i < len; i++)
2042 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2045 /* If this used to be a conditional jump insn but whose branch
2046 direction is now known, we must do something special. */
2047 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2050 /* The previous insn set cc0 for us. So delete it. */
2051 delete_insn (PREV_INSN (copy));
2054 /* If this is now a no-op, delete it. */
2055 if (map->last_pc_value == pc_rtx)
2057 /* Don't let delete_insn delete the label referenced here,
2058 because we might possibly need it later for some other
2059 instruction in the loop. */
2060 if (JUMP_LABEL (copy))
2061 LABEL_NUSES (JUMP_LABEL (copy))++;
2063 if (JUMP_LABEL (copy))
2064 LABEL_NUSES (JUMP_LABEL (copy))--;
2068 /* Otherwise, this is unconditional jump so we must put a
2069 BARRIER after it. We could do some dead code elimination
2070 here, but jump.c will do it just as well. */
2076 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
2077 copy = emit_call_insn (pattern);
2078 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2080 /* Because the USAGE information potentially contains objects other
2081 than hard registers, we need to copy it. */
2082 CALL_INSN_FUNCTION_USAGE (copy)
2083 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn), map);
2087 try_constants (cc0_insn, map);
2090 try_constants (copy, map);
2092 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2093 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2094 map->const_equiv_map[i] = 0;
2098 /* If this is the loop start label, then we don't need to emit a
2099 copy of this label since no one will use it. */
2101 if (insn != start_label)
2103 copy = emit_label (get_label_from_map (map,
2104 CODE_LABEL_NUMBER (insn)));
2110 copy = emit_barrier ();
2114 /* VTOP notes are valid only before the loop exit test. If placed
2115 anywhere else, loop may generate bad code. */
2117 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2118 && (NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2119 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2120 copy = emit_note (NOTE_SOURCE_FILE (insn),
2121 NOTE_LINE_NUMBER (insn));
2131 map->insn_map[INSN_UID (insn)] = copy;
2133 while (insn != copy_end);
2135 /* Now finish coping the REG_NOTES. */
2139 insn = NEXT_INSN (insn);
2140 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2141 || GET_CODE (insn) == CALL_INSN)
2142 && map->insn_map[INSN_UID (insn)])
2143 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2145 while (insn != copy_end);
2147 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2148 each of these notes here, since there may be some important ones, such as
2149 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2150 iteration, because the original notes won't be deleted.
2152 We can't use insert_before here, because when from preconditioning,
2153 insert_before points before the loop. We can't use copy_end, because
2154 there may be insns already inserted after it (which we don't want to
2155 copy) when not from preconditioning code. */
2157 if (! last_iteration)
2159 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2161 if (GET_CODE (insn) == NOTE
2162 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED)
2163 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2167 if (final_label && LABEL_NUSES (final_label) > 0)
2168 emit_label (final_label);
2170 tem = gen_sequence ();
2172 emit_insn_before (tem, insert_before);
2175 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2176 emitted. This will correctly handle the case where the increment value
2177 won't fit in the immediate field of a PLUS insns. */
2180 emit_unrolled_add (dest_reg, src_reg, increment)
2181 rtx dest_reg, src_reg, increment;
2185 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2186 dest_reg, 0, OPTAB_LIB_WIDEN);
2188 if (dest_reg != result)
2189 emit_move_insn (dest_reg, result);
2192 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2193 is a backward branch in that range that branches to somewhere between
2194 LOOP_START and INSN. Returns 0 otherwise. */
2196 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2197 In practice, this is not a problem, because this function is seldom called,
2198 and uses a negligible amount of CPU time on average. */
2201 back_branch_in_range_p (insn, loop_start, loop_end)
2203 rtx loop_start, loop_end;
2205 rtx p, q, target_insn;
2206 rtx orig_loop_end = loop_end;
2208 /* Stop before we get to the backward branch at the end of the loop. */
2209 loop_end = prev_nonnote_insn (loop_end);
2210 if (GET_CODE (loop_end) == BARRIER)
2211 loop_end = PREV_INSN (loop_end);
2213 /* Check in case insn has been deleted, search forward for first non
2214 deleted insn following it. */
2215 while (INSN_DELETED_P (insn))
2216 insn = NEXT_INSN (insn);
2218 /* Check for the case where insn is the last insn in the loop. Deal
2219 with the case where INSN was a deleted loop test insn, in which case
2220 it will now be the NOTE_LOOP_END. */
2221 if (insn == loop_end || insn == orig_loop_end)
2224 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2226 if (GET_CODE (p) == JUMP_INSN)
2228 target_insn = JUMP_LABEL (p);
2230 /* Search from loop_start to insn, to see if one of them is
2231 the target_insn. We can't use INSN_LUID comparisons here,
2232 since insn may not have an LUID entry. */
2233 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2234 if (q == target_insn)
2242 /* Try to generate the simplest rtx for the expression
2243 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2247 fold_rtx_mult_add (mult1, mult2, add1, mode)
2248 rtx mult1, mult2, add1;
2249 enum machine_mode mode;
2254 /* The modes must all be the same. This should always be true. For now,
2255 check to make sure. */
2256 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2257 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2258 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2261 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2262 will be a constant. */
2263 if (GET_CODE (mult1) == CONST_INT)
2270 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2272 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2274 /* Again, put the constant second. */
2275 if (GET_CODE (add1) == CONST_INT)
2282 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2284 result = gen_rtx_PLUS (mode, add1, mult_res);
2289 /* Searches the list of induction struct's for the biv BL, to try to calculate
2290 the total increment value for one iteration of the loop as a constant.
2292 Returns the increment value as an rtx, simplified as much as possible,
2293 if it can be calculated. Otherwise, returns 0. */
2296 biv_total_increment (bl, loop_start, loop_end)
2297 struct iv_class *bl;
2298 rtx loop_start, loop_end;
2300 struct induction *v;
2303 /* For increment, must check every instruction that sets it. Each
2304 instruction must be executed only once each time through the loop.
2305 To verify this, we check that the insn is always executed, and that
2306 there are no backward branches after the insn that branch to before it.
2307 Also, the insn must have a mult_val of one (to make sure it really is
2310 result = const0_rtx;
2311 for (v = bl->biv; v; v = v->next_iv)
2313 if (v->always_computable && v->mult_val == const1_rtx
2314 && ! back_branch_in_range_p (v->insn, loop_start, loop_end))
2315 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2323 /* Determine the initial value of the iteration variable, and the amount
2324 that it is incremented each loop. Use the tables constructed by
2325 the strength reduction pass to calculate these values.
2327 Initial_value and/or increment are set to zero if their values could not
2331 iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
2332 rtx iteration_var, *initial_value, *increment;
2333 rtx loop_start, loop_end;
2335 struct iv_class *bl;
2337 struct induction *v;
2340 /* Clear the result values, in case no answer can be found. */
2344 /* The iteration variable can be either a giv or a biv. Check to see
2345 which it is, and compute the variable's initial value, and increment
2346 value if possible. */
2348 /* If this is a new register, can't handle it since we don't have any
2349 reg_iv_type entry for it. */
2350 if (REGNO (iteration_var) >= max_reg_before_loop)
2352 if (loop_dump_stream)
2353 fprintf (loop_dump_stream,
2354 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2358 /* Reject iteration variables larger than the host wide int size, since they
2359 could result in a number of iterations greater than the range of our
2360 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2361 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2362 > HOST_BITS_PER_WIDE_INT))
2364 if (loop_dump_stream)
2365 fprintf (loop_dump_stream,
2366 "Loop unrolling: Iteration var rejected because mode too large.\n");
2369 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2371 if (loop_dump_stream)
2372 fprintf (loop_dump_stream,
2373 "Loop unrolling: Iteration var not an integer.\n");
2376 else if (reg_iv_type[REGNO (iteration_var)] == BASIC_INDUCT)
2378 /* Grab initial value, only useful if it is a constant. */
2379 bl = reg_biv_class[REGNO (iteration_var)];
2380 *initial_value = bl->initial_value;
2382 *increment = biv_total_increment (bl, loop_start, loop_end);
2384 else if (reg_iv_type[REGNO (iteration_var)] == GENERAL_INDUCT)
2387 /* ??? The code below does not work because the incorrect number of
2388 iterations is calculated when the biv is incremented after the giv
2389 is set (which is the usual case). This can probably be accounted
2390 for by biasing the initial_value by subtracting the amount of the
2391 increment that occurs between the giv set and the giv test. However,
2392 a giv as an iterator is very rare, so it does not seem worthwhile
2394 /* ??? An example failure is: i = 6; do {;} while (i++ < 9). */
2395 if (loop_dump_stream)
2396 fprintf (loop_dump_stream,
2397 "Loop unrolling: Giv iterators are not handled.\n");
2400 /* Initial value is mult_val times the biv's initial value plus
2401 add_val. Only useful if it is a constant. */
2402 v = reg_iv_info[REGNO (iteration_var)];
2403 bl = reg_biv_class[REGNO (v->src_reg)];
2404 *initial_value = fold_rtx_mult_add (v->mult_val, bl->initial_value,
2405 v->add_val, v->mode);
2407 /* Increment value is mult_val times the increment value of the biv. */
2409 *increment = biv_total_increment (bl, loop_start, loop_end);
2411 *increment = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx,
2417 if (loop_dump_stream)
2418 fprintf (loop_dump_stream,
2419 "Loop unrolling: Not basic or general induction var.\n");
2424 /* Calculate the approximate final value of the iteration variable
2425 which has an loop exit test with code COMPARISON_CODE and comparison value
2426 of COMPARISON_VALUE. Also returns an indication of whether the comparison
2427 was signed or unsigned, and the direction of the comparison. This info is
2428 needed to calculate the number of loop iterations. */
2431 approx_final_value (comparison_code, comparison_value, unsigned_p, compare_dir)
2432 enum rtx_code comparison_code;
2433 rtx comparison_value;
2437 /* Calculate the final value of the induction variable.
2438 The exact final value depends on the branch operator, and increment sign.
2439 This is only an approximate value. It will be wrong if the iteration
2440 variable is not incremented by one each time through the loop, and
2441 approx final value - start value % increment != 0. */
2444 switch (comparison_code)
2450 return plus_constant (comparison_value, 1);
2455 return plus_constant (comparison_value, -1);
2457 /* Can not calculate a final value for this case. */
2464 return comparison_value;
2470 return comparison_value;
2473 return comparison_value;
2479 /* For each biv and giv, determine whether it can be safely split into
2480 a different variable for each unrolled copy of the loop body. If it
2481 is safe to split, then indicate that by saving some useful info
2482 in the splittable_regs array.
2484 If the loop is being completely unrolled, then splittable_regs will hold
2485 the current value of the induction variable while the loop is unrolled.
2486 It must be set to the initial value of the induction variable here.
2487 Otherwise, splittable_regs will hold the difference between the current
2488 value of the induction variable and the value the induction variable had
2489 at the top of the loop. It must be set to the value 0 here.
2491 Returns the total number of instructions that set registers that are
2494 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2495 constant values are unnecessary, since we can easily calculate increment
2496 values in this case even if nothing is constant. The increment value
2497 should not involve a multiply however. */
2499 /* ?? Even if the biv/giv increment values aren't constant, it may still
2500 be beneficial to split the variable if the loop is only unrolled a few
2501 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2504 find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
2505 unroll_number, n_iterations)
2506 enum unroll_types unroll_type;
2507 rtx loop_start, loop_end;
2508 rtx end_insert_before;
2510 unsigned HOST_WIDE_INT n_iterations;
2512 struct iv_class *bl;
2513 struct induction *v;
2515 rtx biv_final_value;
2519 for (bl = loop_iv_list; bl; bl = bl->next)
2521 /* Biv_total_increment must return a constant value,
2522 otherwise we can not calculate the split values. */
2524 increment = biv_total_increment (bl, loop_start, loop_end);
2525 if (! increment || GET_CODE (increment) != CONST_INT)
2528 /* The loop must be unrolled completely, or else have a known number
2529 of iterations and only one exit, or else the biv must be dead
2530 outside the loop, or else the final value must be known. Otherwise,
2531 it is unsafe to split the biv since it may not have the proper
2532 value on loop exit. */
2534 /* loop_number_exit_count is non-zero if the loop has an exit other than
2535 a fall through at the end. */
2538 biv_final_value = 0;
2539 if (unroll_type != UNROLL_COMPLETELY
2540 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2541 || unroll_type == UNROLL_NAIVE)
2542 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2544 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2545 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2546 < INSN_LUID (bl->init_insn))
2547 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2548 && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end,
2552 /* If any of the insns setting the BIV don't do so with a simple
2553 PLUS, we don't know how to split it. */
2554 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2555 if ((tem = single_set (v->insn)) == 0
2556 || GET_CODE (SET_DEST (tem)) != REG
2557 || REGNO (SET_DEST (tem)) != bl->regno
2558 || GET_CODE (SET_SRC (tem)) != PLUS)
2561 /* If final value is non-zero, then must emit an instruction which sets
2562 the value of the biv to the proper value. This is done after
2563 handling all of the givs, since some of them may need to use the
2564 biv's value in their initialization code. */
2566 /* This biv is splittable. If completely unrolling the loop, save
2567 the biv's initial value. Otherwise, save the constant zero. */
2569 if (biv_splittable == 1)
2571 if (unroll_type == UNROLL_COMPLETELY)
2573 /* If the initial value of the biv is itself (i.e. it is too
2574 complicated for strength_reduce to compute), or is a hard
2575 register, or it isn't invariant, then we must create a new
2576 pseudo reg to hold the initial value of the biv. */
2578 if (GET_CODE (bl->initial_value) == REG
2579 && (REGNO (bl->initial_value) == bl->regno
2580 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2581 || ! invariant_p (bl->initial_value)))
2583 rtx tem = gen_reg_rtx (bl->biv->mode);
2585 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2586 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2589 if (loop_dump_stream)
2590 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2591 bl->regno, REGNO (tem));
2593 splittable_regs[bl->regno] = tem;
2596 splittable_regs[bl->regno] = bl->initial_value;
2599 splittable_regs[bl->regno] = const0_rtx;
2601 /* Save the number of instructions that modify the biv, so that
2602 we can treat the last one specially. */
2604 splittable_regs_updates[bl->regno] = bl->biv_count;
2605 result += bl->biv_count;
2607 if (loop_dump_stream)
2608 fprintf (loop_dump_stream,
2609 "Biv %d safe to split.\n", bl->regno);
2612 /* Check every giv that depends on this biv to see whether it is
2613 splittable also. Even if the biv isn't splittable, givs which
2614 depend on it may be splittable if the biv is live outside the
2615 loop, and the givs aren't. */
2617 result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
2618 increment, unroll_number);
2620 /* If final value is non-zero, then must emit an instruction which sets
2621 the value of the biv to the proper value. This is done after
2622 handling all of the givs, since some of them may need to use the
2623 biv's value in their initialization code. */
2624 if (biv_final_value)
2626 /* If the loop has multiple exits, emit the insns before the
2627 loop to ensure that it will always be executed no matter
2628 how the loop exits. Otherwise emit the insn after the loop,
2629 since this is slightly more efficient. */
2630 if (! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
2631 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2636 /* Create a new register to hold the value of the biv, and then
2637 set the biv to its final value before the loop start. The biv
2638 is set to its final value before loop start to ensure that
2639 this insn will always be executed, no matter how the loop
2641 rtx tem = gen_reg_rtx (bl->biv->mode);
2642 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2644 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2646 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2650 if (loop_dump_stream)
2651 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2652 REGNO (bl->biv->src_reg), REGNO (tem));
2654 /* Set up the mapping from the original biv register to the new
2656 bl->biv->src_reg = tem;
2663 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2664 for the instruction that is using it. Do not make any changes to that
2668 verify_addresses (v, giv_inc, unroll_number)
2669 struct induction *v;
2674 rtx orig_addr = *v->location;
2675 rtx last_addr = plus_constant (v->dest_reg,
2676 INTVAL (giv_inc) * (unroll_number - 1));
2678 /* First check to see if either address would fail. Handle the fact
2679 that we have may have a match_dup. */
2680 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2681 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2684 /* Now put things back the way they were before. This should always
2686 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2692 /* For every giv based on the biv BL, check to determine whether it is
2693 splittable. This is a subroutine to find_splittable_regs ().
2695 Return the number of instructions that set splittable registers. */
2698 find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
2700 struct iv_class *bl;
2701 enum unroll_types unroll_type;
2702 rtx loop_start, loop_end;
2706 struct induction *v, *v2;
2711 /* Scan the list of givs, and set the same_insn field when there are
2712 multiple identical givs in the same insn. */
2713 for (v = bl->giv; v; v = v->next_iv)
2714 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2715 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2719 for (v = bl->giv; v; v = v->next_iv)
2723 /* Only split the giv if it has already been reduced, or if the loop is
2724 being completely unrolled. */
2725 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2728 /* The giv can be split if the insn that sets the giv is executed once
2729 and only once on every iteration of the loop. */
2730 /* An address giv can always be split. v->insn is just a use not a set,
2731 and hence it does not matter whether it is always executed. All that
2732 matters is that all the biv increments are always executed, and we
2733 won't reach here if they aren't. */
2734 if (v->giv_type != DEST_ADDR
2735 && (! v->always_computable
2736 || back_branch_in_range_p (v->insn, loop_start, loop_end)))
2739 /* The giv increment value must be a constant. */
2740 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2742 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2745 /* The loop must be unrolled completely, or else have a known number of
2746 iterations and only one exit, or else the giv must be dead outside
2747 the loop, or else the final value of the giv must be known.
2748 Otherwise, it is not safe to split the giv since it may not have the
2749 proper value on loop exit. */
2751 /* The used outside loop test will fail for DEST_ADDR givs. They are
2752 never used outside the loop anyways, so it is always safe to split a
2756 if (unroll_type != UNROLL_COMPLETELY
2757 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2758 || unroll_type == UNROLL_NAIVE)
2759 && v->giv_type != DEST_ADDR
2760 /* The next part is true if the pseudo is used outside the loop.
2761 We assume that this is true for any pseudo created after loop
2762 starts, because we don't have a reg_n_info entry for them. */
2763 && (REGNO (v->dest_reg) >= max_reg_before_loop
2764 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2765 /* Check for the case where the pseudo is set by a shift/add
2766 sequence, in which case the first insn setting the pseudo
2767 is the first insn of the shift/add sequence. */
2768 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2769 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2770 != INSN_UID (XEXP (tem, 0)))))
2771 /* Line above always fails if INSN was moved by loop opt. */
2772 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2773 >= INSN_LUID (loop_end)))
2774 && ! (final_value = v->final_value))
2778 /* Currently, non-reduced/final-value givs are never split. */
2779 /* Should emit insns after the loop if possible, as the biv final value
2782 /* If the final value is non-zero, and the giv has not been reduced,
2783 then must emit an instruction to set the final value. */
2784 if (final_value && !v->new_reg)
2786 /* Create a new register to hold the value of the giv, and then set
2787 the giv to its final value before the loop start. The giv is set
2788 to its final value before loop start to ensure that this insn
2789 will always be executed, no matter how we exit. */
2790 tem = gen_reg_rtx (v->mode);
2791 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2792 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2795 if (loop_dump_stream)
2796 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2797 REGNO (v->dest_reg), REGNO (tem));
2803 /* This giv is splittable. If completely unrolling the loop, save the
2804 giv's initial value. Otherwise, save the constant zero for it. */
2806 if (unroll_type == UNROLL_COMPLETELY)
2808 /* It is not safe to use bl->initial_value here, because it may not
2809 be invariant. It is safe to use the initial value stored in
2810 the splittable_regs array if it is set. In rare cases, it won't
2811 be set, so then we do exactly the same thing as
2812 find_splittable_regs does to get a safe value. */
2813 rtx biv_initial_value;
2815 if (splittable_regs[bl->regno])
2816 biv_initial_value = splittable_regs[bl->regno];
2817 else if (GET_CODE (bl->initial_value) != REG
2818 || (REGNO (bl->initial_value) != bl->regno
2819 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2820 biv_initial_value = bl->initial_value;
2823 rtx tem = gen_reg_rtx (bl->biv->mode);
2825 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2826 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2828 biv_initial_value = tem;
2830 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2831 v->add_val, v->mode);
2838 /* If a giv was combined with another giv, then we can only split
2839 this giv if the giv it was combined with was reduced. This
2840 is because the value of v->new_reg is meaningless in this
2842 if (v->same && ! v->same->new_reg)
2844 if (loop_dump_stream)
2845 fprintf (loop_dump_stream,
2846 "giv combined with unreduced giv not split.\n");
2849 /* If the giv is an address destination, it could be something other
2850 than a simple register, these have to be treated differently. */
2851 else if (v->giv_type == DEST_REG)
2853 /* If value is not a constant, register, or register plus
2854 constant, then compute its value into a register before
2855 loop start. This prevents invalid rtx sharing, and should
2856 generate better code. We can use bl->initial_value here
2857 instead of splittable_regs[bl->regno] because this code
2858 is going before the loop start. */
2859 if (unroll_type == UNROLL_COMPLETELY
2860 && GET_CODE (value) != CONST_INT
2861 && GET_CODE (value) != REG
2862 && (GET_CODE (value) != PLUS
2863 || GET_CODE (XEXP (value, 0)) != REG
2864 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2866 rtx tem = gen_reg_rtx (v->mode);
2867 record_base_value (REGNO (tem), v->add_val, 0);
2868 emit_iv_add_mult (bl->initial_value, v->mult_val,
2869 v->add_val, tem, loop_start);
2873 splittable_regs[REGNO (v->new_reg)] = value;
2877 /* Splitting address givs is useful since it will often allow us
2878 to eliminate some increment insns for the base giv as
2881 /* If the addr giv is combined with a dest_reg giv, then all
2882 references to that dest reg will be remapped, which is NOT
2883 what we want for split addr regs. We always create a new
2884 register for the split addr giv, just to be safe. */
2886 /* If we have multiple identical address givs within a
2887 single instruction, then use a single pseudo reg for
2888 both. This is necessary in case one is a match_dup
2891 v->const_adjust = 0;
2895 v->dest_reg = v->same_insn->dest_reg;
2896 if (loop_dump_stream)
2897 fprintf (loop_dump_stream,
2898 "Sharing address givs in insn %d\n",
2899 INSN_UID (v->insn));
2901 /* If multiple address GIVs have been combined with the
2902 same dest_reg GIV, do not create a new register for
2904 else if (unroll_type != UNROLL_COMPLETELY
2905 && v->giv_type == DEST_ADDR
2906 && v->same && v->same->giv_type == DEST_ADDR
2907 && v->same->unrolled
2908 /* combine_givs_p may return true for some cases
2909 where the add and mult values are not equal.
2910 To share a register here, the values must be
2912 && rtx_equal_p (v->same->mult_val, v->mult_val)
2913 && rtx_equal_p (v->same->add_val, v->add_val))
2916 v->dest_reg = v->same->dest_reg;
2919 else if (unroll_type != UNROLL_COMPLETELY)
2921 /* If not completely unrolling the loop, then create a new
2922 register to hold the split value of the DEST_ADDR giv.
2923 Emit insn to initialize its value before loop start. */
2925 rtx tem = gen_reg_rtx (v->mode);
2926 record_base_value (REGNO (tem), v->add_val, 0);
2928 /* If the address giv has a constant in its new_reg value,
2929 then this constant can be pulled out and put in value,
2930 instead of being part of the initialization code. */
2932 if (GET_CODE (v->new_reg) == PLUS
2933 && GET_CODE (XEXP (v->new_reg, 1)) == CONST_INT)
2936 = plus_constant (tem, INTVAL (XEXP (v->new_reg,1)));
2938 /* Only succeed if this will give valid addresses.
2939 Try to validate both the first and the last
2940 address resulting from loop unrolling, if
2941 one fails, then can't do const elim here. */
2942 if (verify_addresses (v, giv_inc, unroll_number))
2944 /* Save the negative of the eliminated const, so
2945 that we can calculate the dest_reg's increment
2947 v->const_adjust = - INTVAL (XEXP (v->new_reg, 1));
2949 v->new_reg = XEXP (v->new_reg, 0);
2950 if (loop_dump_stream)
2951 fprintf (loop_dump_stream,
2952 "Eliminating constant from giv %d\n",
2961 /* If the address hasn't been checked for validity yet, do so
2962 now, and fail completely if either the first or the last
2963 unrolled copy of the address is not a valid address
2964 for the instruction that uses it. */
2965 if (v->dest_reg == tem
2966 && ! verify_addresses (v, giv_inc, unroll_number))
2968 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2969 if (v2->same_insn == v)
2972 if (loop_dump_stream)
2973 fprintf (loop_dump_stream,
2974 "Invalid address for giv at insn %d\n",
2975 INSN_UID (v->insn));
2979 /* We set this after the address check, to guarantee that
2980 the register will be initialized. */
2983 /* To initialize the new register, just move the value of
2984 new_reg into it. This is not guaranteed to give a valid
2985 instruction on machines with complex addressing modes.
2986 If we can't recognize it, then delete it and emit insns
2987 to calculate the value from scratch. */
2988 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
2989 copy_rtx (v->new_reg)),
2991 if (recog_memoized (PREV_INSN (loop_start)) < 0)
2995 /* We can't use bl->initial_value to compute the initial
2996 value, because the loop may have been preconditioned.
2997 We must calculate it from NEW_REG. Try using
2998 force_operand instead of emit_iv_add_mult. */
2999 delete_insn (PREV_INSN (loop_start));
3002 ret = force_operand (v->new_reg, tem);
3004 emit_move_insn (tem, ret);
3005 sequence = gen_sequence ();
3007 emit_insn_before (sequence, loop_start);
3009 if (loop_dump_stream)
3010 fprintf (loop_dump_stream,
3011 "Invalid init insn, rewritten.\n");
3016 v->dest_reg = value;
3018 /* Check the resulting address for validity, and fail
3019 if the resulting address would be invalid. */
3020 if (! verify_addresses (v, giv_inc, unroll_number))
3022 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3023 if (v2->same_insn == v)
3026 if (loop_dump_stream)
3027 fprintf (loop_dump_stream,
3028 "Invalid address for giv at insn %d\n",
3029 INSN_UID (v->insn));
3034 /* Store the value of dest_reg into the insn. This sharing
3035 will not be a problem as this insn will always be copied
3038 *v->location = v->dest_reg;
3040 /* If this address giv is combined with a dest reg giv, then
3041 save the base giv's induction pointer so that we will be
3042 able to handle this address giv properly. The base giv
3043 itself does not have to be splittable. */
3045 if (v->same && v->same->giv_type == DEST_REG)
3046 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3048 if (GET_CODE (v->new_reg) == REG)
3050 /* This giv maybe hasn't been combined with any others.
3051 Make sure that it's giv is marked as splittable here. */
3053 splittable_regs[REGNO (v->new_reg)] = value;
3055 /* Make it appear to depend upon itself, so that the
3056 giv will be properly split in the main loop above. */
3060 addr_combined_regs[REGNO (v->new_reg)] = v;
3064 if (loop_dump_stream)
3065 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3071 /* Currently, unreduced giv's can't be split. This is not too much
3072 of a problem since unreduced giv's are not live across loop
3073 iterations anyways. When unrolling a loop completely though,
3074 it makes sense to reduce&split givs when possible, as this will
3075 result in simpler instructions, and will not require that a reg
3076 be live across loop iterations. */
3078 splittable_regs[REGNO (v->dest_reg)] = value;
3079 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3080 REGNO (v->dest_reg), INSN_UID (v->insn));
3086 /* Unreduced givs are only updated once by definition. Reduced givs
3087 are updated as many times as their biv is. Mark it so if this is
3088 a splittable register. Don't need to do anything for address givs
3089 where this may not be a register. */
3091 if (GET_CODE (v->new_reg) == REG)
3095 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3097 splittable_regs_updates[REGNO (v->new_reg)] = count;
3102 if (loop_dump_stream)
3106 if (GET_CODE (v->dest_reg) == CONST_INT)
3108 else if (GET_CODE (v->dest_reg) != REG)
3109 regnum = REGNO (XEXP (v->dest_reg, 0));
3111 regnum = REGNO (v->dest_reg);
3112 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3113 regnum, INSN_UID (v->insn));
3120 /* Try to prove that the register is dead after the loop exits. Trace every
3121 loop exit looking for an insn that will always be executed, which sets
3122 the register to some value, and appears before the first use of the register
3123 is found. If successful, then return 1, otherwise return 0. */
3125 /* ?? Could be made more intelligent in the handling of jumps, so that
3126 it can search past if statements and other similar structures. */
3129 reg_dead_after_loop (reg, loop_start, loop_end)
3130 rtx reg, loop_start, loop_end;
3135 int label_count = 0;
3136 int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
3138 /* In addition to checking all exits of this loop, we must also check
3139 all exits of inner nested loops that would exit this loop. We don't
3140 have any way to identify those, so we just give up if there are any
3141 such inner loop exits. */
3143 for (label = loop_number_exit_labels[this_loop_num]; label;
3144 label = LABEL_NEXTREF (label))
3147 if (label_count != loop_number_exit_count[this_loop_num])
3150 /* HACK: Must also search the loop fall through exit, create a label_ref
3151 here which points to the loop_end, and append the loop_number_exit_labels
3153 label = gen_rtx_LABEL_REF (VOIDmode, loop_end);
3154 LABEL_NEXTREF (label) = loop_number_exit_labels[this_loop_num];
3156 for ( ; label; label = LABEL_NEXTREF (label))
3158 /* Succeed if find an insn which sets the biv or if reach end of
3159 function. Fail if find an insn that uses the biv, or if come to
3160 a conditional jump. */
3162 insn = NEXT_INSN (XEXP (label, 0));
3165 code = GET_CODE (insn);
3166 if (GET_RTX_CLASS (code) == 'i')
3170 if (reg_referenced_p (reg, PATTERN (insn)))
3173 set = single_set (insn);
3174 if (set && rtx_equal_p (SET_DEST (set), reg))
3178 if (code == JUMP_INSN)
3180 if (GET_CODE (PATTERN (insn)) == RETURN)
3182 else if (! simplejump_p (insn)
3183 /* Prevent infinite loop following infinite loops. */
3184 || jump_count++ > 20)
3187 insn = JUMP_LABEL (insn);
3190 insn = NEXT_INSN (insn);
3194 /* Success, the register is dead on all loop exits. */
3198 /* Try to calculate the final value of the biv, the value it will have at
3199 the end of the loop. If we can do it, return that value. */
3202 final_biv_value (bl, loop_start, loop_end, n_iterations)
3203 struct iv_class *bl;
3204 rtx loop_start, loop_end;
3205 unsigned HOST_WIDE_INT n_iterations;
3209 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3211 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3214 /* The final value for reversed bivs must be calculated differently than
3215 for ordinary bivs. In this case, there is already an insn after the
3216 loop which sets this biv's final value (if necessary), and there are
3217 no other loop exits, so we can return any value. */
3220 if (loop_dump_stream)
3221 fprintf (loop_dump_stream,
3222 "Final biv value for %d, reversed biv.\n", bl->regno);
3227 /* Try to calculate the final value as initial value + (number of iterations
3228 * increment). For this to work, increment must be invariant, the only
3229 exit from the loop must be the fall through at the bottom (otherwise
3230 it may not have its final value when the loop exits), and the initial
3231 value of the biv must be invariant. */
3233 if (n_iterations != 0
3234 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
3235 && invariant_p (bl->initial_value))
3237 increment = biv_total_increment (bl, loop_start, loop_end);
3239 if (increment && invariant_p (increment))
3241 /* Can calculate the loop exit value, emit insns after loop
3242 end to calculate this value into a temporary register in
3243 case it is needed later. */
3245 tem = gen_reg_rtx (bl->biv->mode);
3246 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3247 /* Make sure loop_end is not the last insn. */
3248 if (NEXT_INSN (loop_end) == 0)
3249 emit_note_after (NOTE_INSN_DELETED, loop_end);
3250 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3251 bl->initial_value, tem, NEXT_INSN (loop_end));
3253 if (loop_dump_stream)
3254 fprintf (loop_dump_stream,
3255 "Final biv value for %d, calculated.\n", bl->regno);
3261 /* Check to see if the biv is dead at all loop exits. */
3262 if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
3264 if (loop_dump_stream)
3265 fprintf (loop_dump_stream,
3266 "Final biv value for %d, biv dead after loop exit.\n",
3275 /* Try to calculate the final value of the giv, the value it will have at
3276 the end of the loop. If we can do it, return that value. */
3279 final_giv_value (v, loop_start, loop_end, n_iterations)
3280 struct induction *v;
3281 rtx loop_start, loop_end;
3282 unsigned HOST_WIDE_INT n_iterations;
3284 struct iv_class *bl;
3287 rtx insert_before, seq;
3289 bl = reg_biv_class[REGNO (v->src_reg)];
3291 /* The final value for givs which depend on reversed bivs must be calculated
3292 differently than for ordinary givs. In this case, there is already an
3293 insn after the loop which sets this giv's final value (if necessary),
3294 and there are no other loop exits, so we can return any value. */
3297 if (loop_dump_stream)
3298 fprintf (loop_dump_stream,
3299 "Final giv value for %d, depends on reversed biv\n",
3300 REGNO (v->dest_reg));
3304 /* Try to calculate the final value as a function of the biv it depends
3305 upon. The only exit from the loop must be the fall through at the bottom
3306 (otherwise it may not have its final value when the loop exits). */
3308 /* ??? Can calculate the final giv value by subtracting off the
3309 extra biv increments times the giv's mult_val. The loop must have
3310 only one exit for this to work, but the loop iterations does not need
3313 if (n_iterations != 0
3314 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
3316 /* ?? It is tempting to use the biv's value here since these insns will
3317 be put after the loop, and hence the biv will have its final value
3318 then. However, this fails if the biv is subsequently eliminated.
3319 Perhaps determine whether biv's are eliminable before trying to
3320 determine whether giv's are replaceable so that we can use the
3321 biv value here if it is not eliminable. */
3323 /* We are emitting code after the end of the loop, so we must make
3324 sure that bl->initial_value is still valid then. It will still
3325 be valid if it is invariant. */
3327 increment = biv_total_increment (bl, loop_start, loop_end);
3329 if (increment && invariant_p (increment)
3330 && invariant_p (bl->initial_value))
3332 /* Can calculate the loop exit value of its biv as
3333 (n_iterations * increment) + initial_value */
3335 /* The loop exit value of the giv is then
3336 (final_biv_value - extra increments) * mult_val + add_val.
3337 The extra increments are any increments to the biv which
3338 occur in the loop after the giv's value is calculated.
3339 We must search from the insn that sets the giv to the end
3340 of the loop to calculate this value. */
3342 insert_before = NEXT_INSN (loop_end);
3344 /* Put the final biv value in tem. */
3345 tem = gen_reg_rtx (bl->biv->mode);
3346 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3347 emit_iv_add_mult (increment, GEN_INT (n_iterations),
3348 bl->initial_value, tem, insert_before);
3350 /* Subtract off extra increments as we find them. */
3351 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3352 insn = NEXT_INSN (insn))
3354 struct induction *biv;
3356 for (biv = bl->biv; biv; biv = biv->next_iv)
3357 if (biv->insn == insn)
3360 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3361 biv->add_val, NULL_RTX, 0,
3363 seq = gen_sequence ();
3365 emit_insn_before (seq, insert_before);
3369 /* Now calculate the giv's final value. */
3370 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3373 if (loop_dump_stream)
3374 fprintf (loop_dump_stream,
3375 "Final giv value for %d, calc from biv's value.\n",
3376 REGNO (v->dest_reg));
3382 /* Replaceable giv's should never reach here. */
3386 /* Check to see if the biv is dead at all loop exits. */
3387 if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
3389 if (loop_dump_stream)
3390 fprintf (loop_dump_stream,
3391 "Final giv value for %d, giv dead after loop exit.\n",
3392 REGNO (v->dest_reg));
3401 /* Calculate the number of loop iterations. Returns the exact number of loop
3402 iterations if it can be calculated, otherwise returns zero. */
3404 unsigned HOST_WIDE_INT
3405 loop_iterations (loop_start, loop_end, loop_info)
3406 rtx loop_start, loop_end;
3407 struct loop_info *loop_info;
3409 rtx comparison, comparison_value;
3410 rtx iteration_var, initial_value, increment, final_value;
3411 enum rtx_code comparison_code;
3414 int unsigned_compare, compare_dir, final_larger;
3415 unsigned long tempu;
3418 /* First find the iteration variable. If the last insn is a conditional
3419 branch, and the insn before tests a register value, make that the
3420 iteration variable. */
3422 loop_info->initial_value = 0;
3423 loop_info->increment = 0;
3424 loop_info->final_value = 0;
3425 loop_info->iteration_var = 0;
3426 loop_info->unroll_number = 2;
3428 /* We used to use pren_nonnote_insn here, but that fails because it might
3429 accidentally get the branch for a contained loop if the branch for this
3430 loop was deleted. We can only trust branches immediately before the
3432 last_loop_insn = PREV_INSN (loop_end);
3434 comparison = get_condition_for_loop (last_loop_insn);
3435 if (comparison == 0)
3437 if (loop_dump_stream)
3438 fprintf (loop_dump_stream,
3439 "Loop unrolling: No final conditional branch found.\n");
3443 /* ??? Get_condition may switch position of induction variable and
3444 invariant register when it canonicalizes the comparison. */
3446 comparison_code = GET_CODE (comparison);
3447 iteration_var = XEXP (comparison, 0);
3448 comparison_value = XEXP (comparison, 1);
3450 if (GET_CODE (iteration_var) != REG)
3452 if (loop_dump_stream)
3453 fprintf (loop_dump_stream,
3454 "Loop unrolling: Comparison not against register.\n");
3458 /* Loop iterations is always called before any new registers are created
3459 now, so this should never occur. */
3461 if (REGNO (iteration_var) >= max_reg_before_loop)
3464 iteration_info (iteration_var, &initial_value, &increment,
3465 loop_start, loop_end);
3466 if (initial_value == 0)
3467 /* iteration_info already printed a message. */
3470 /* If the comparison value is an invariant register, then try to find
3471 its value from the insns before the start of the loop. */
3473 if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
3477 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3479 if (GET_CODE (insn) == CODE_LABEL)
3482 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3483 && reg_set_p (comparison_value, insn))
3485 /* We found the last insn before the loop that sets the register.
3486 If it sets the entire register, and has a REG_EQUAL note,
3487 then use the value of the REG_EQUAL note. */
3488 if ((set = single_set (insn))
3489 && (SET_DEST (set) == comparison_value))
3491 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3493 /* Only use the REG_EQUAL note if it is a constant.
3494 Other things, divide in particular, will cause
3495 problems later if we use them. */
3496 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3497 && CONSTANT_P (XEXP (note, 0)))
3498 comparison_value = XEXP (note, 0);
3505 final_value = approx_final_value (comparison_code, comparison_value,
3506 &unsigned_compare, &compare_dir);
3508 /* Save the calculated values describing this loop's bounds, in case
3509 precondition_loop_p will need them later. These values can not be
3510 recalculated inside precondition_loop_p because strength reduction
3511 optimizations may obscure the loop's structure. */
3513 loop_info->iteration_var = iteration_var;
3514 loop_info->initial_value = initial_value;
3515 loop_info->increment = increment;
3516 loop_info->final_value = final_value;
3517 loop_info->comparison_code = comparison_code;
3521 if (loop_dump_stream)
3522 fprintf (loop_dump_stream,
3523 "Loop unrolling: Increment value can't be calculated.\n");
3526 else if (GET_CODE (increment) != CONST_INT)
3528 if (loop_dump_stream)
3529 fprintf (loop_dump_stream,
3530 "Loop unrolling: Increment value not constant.\n");
3533 else if (GET_CODE (initial_value) != CONST_INT)
3535 if (loop_dump_stream)
3536 fprintf (loop_dump_stream,
3537 "Loop unrolling: Initial value not constant.\n");
3540 else if (final_value == 0)
3542 if (loop_dump_stream)
3543 fprintf (loop_dump_stream,
3544 "Loop unrolling: EQ comparison loop.\n");
3547 else if (GET_CODE (final_value) != CONST_INT)
3549 if (loop_dump_stream)
3550 fprintf (loop_dump_stream,
3551 "Loop unrolling: Final value not constant.\n");
3555 /* ?? Final value and initial value do not have to be constants.
3556 Only their difference has to be constant. When the iteration variable
3557 is an array address, the final value and initial value might both
3558 be addresses with the same base but different constant offsets.
3559 Final value must be invariant for this to work.
3561 To do this, need some way to find the values of registers which are
3564 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3565 if (unsigned_compare)
3567 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3568 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3569 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3570 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3572 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3573 - (INTVAL (final_value) < INTVAL (initial_value));
3575 if (INTVAL (increment) > 0)
3577 else if (INTVAL (increment) == 0)
3582 /* There are 27 different cases: compare_dir = -1, 0, 1;
3583 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3584 There are 4 normal cases, 4 reverse cases (where the iteration variable
3585 will overflow before the loop exits), 4 infinite loop cases, and 15
3586 immediate exit (0 or 1 iteration depending on loop type) cases.
3587 Only try to optimize the normal cases. */
3589 /* (compare_dir/final_larger/increment_dir)
3590 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3591 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3592 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3593 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3595 /* ?? If the meaning of reverse loops (where the iteration variable
3596 will overflow before the loop exits) is undefined, then could
3597 eliminate all of these special checks, and just always assume
3598 the loops are normal/immediate/infinite. Note that this means
3599 the sign of increment_dir does not have to be known. Also,
3600 since it does not really hurt if immediate exit loops or infinite loops
3601 are optimized, then that case could be ignored also, and hence all
3602 loops can be optimized.
3604 According to ANSI Spec, the reverse loop case result is undefined,
3605 because the action on overflow is undefined.
3607 See also the special test for NE loops below. */
3609 if (final_larger == increment_dir && final_larger != 0
3610 && (final_larger == compare_dir || compare_dir == 0))
3615 if (loop_dump_stream)
3616 fprintf (loop_dump_stream,
3617 "Loop unrolling: Not normal loop.\n");
3621 /* Calculate the number of iterations, final_value is only an approximation,
3622 so correct for that. Note that tempu and loop_info->n_iterations are
3623 unsigned, because they can be as large as 2^n - 1. */
3625 i = INTVAL (increment);
3627 tempu = INTVAL (final_value) - INTVAL (initial_value);
3630 tempu = INTVAL (initial_value) - INTVAL (final_value);
3636 /* For NE tests, make sure that the iteration variable won't miss the
3637 final value. If tempu mod i is not zero, then the iteration variable
3638 will overflow before the loop exits, and we can not calculate the
3639 number of iterations. */
3640 if (compare_dir == 0 && (tempu % i) != 0)
3643 return tempu / i + ((tempu % i) != 0);
3646 /* Replace uses of split bivs with their split pseudo register. This is
3647 for original instructions which remain after loop unrolling without
3651 remap_split_bivs (x)
3654 register enum rtx_code code;
3661 code = GET_CODE (x);
3676 /* If non-reduced/final-value givs were split, then this would also
3677 have to remap those givs also. */
3679 if (REGNO (x) < max_reg_before_loop
3680 && reg_iv_type[REGNO (x)] == BASIC_INDUCT)
3681 return reg_biv_class[REGNO (x)]->biv->src_reg;
3688 fmt = GET_RTX_FORMAT (code);
3689 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3692 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
3696 for (j = 0; j < XVECLEN (x, i); j++)
3697 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
3703 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3704 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3705 return 0. COPY_START is where we can start looking for the insns
3706 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3709 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3710 must dominate LAST_UID.
3712 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3713 may not dominate LAST_UID.
3715 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3716 must dominate LAST_UID. */
3719 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
3726 int passed_jump = 0;
3727 rtx p = NEXT_INSN (copy_start);
3729 while (INSN_UID (p) != first_uid)
3731 if (GET_CODE (p) == JUMP_INSN)
3733 /* Could not find FIRST_UID. */
3739 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
3740 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
3741 || ! dead_or_set_regno_p (p, regno))
3744 /* FIRST_UID is always executed. */
3745 if (passed_jump == 0)
3748 while (INSN_UID (p) != last_uid)
3750 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
3751 can not be sure that FIRST_UID dominates LAST_UID. */
3752 if (GET_CODE (p) == CODE_LABEL)
3754 /* Could not find LAST_UID, but we reached the end of the loop, so
3756 else if (p == copy_end)
3761 /* FIRST_UID is always executed if LAST_UID is executed. */