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"
160 /* This controls which loops are unrolled, and by how much we unroll
163 #ifndef MAX_UNROLLED_INSNS
164 #define MAX_UNROLLED_INSNS 100
167 /* Indexed by register number, if non-zero, then it contains a pointer
168 to a struct induction for a DEST_REG giv which has been combined with
169 one of more address givs. This is needed because whenever such a DEST_REG
170 giv is modified, we must modify the value of all split address givs
171 that were combined with this DEST_REG giv. */
173 static struct induction **addr_combined_regs;
175 /* Indexed by register number, if this is a splittable induction variable,
176 then this will hold the current value of the register, which depends on the
179 static rtx *splittable_regs;
181 /* Indexed by register number, if this is a splittable induction variable,
182 then this will hold the number of instructions in the loop that modify
183 the induction variable. Used to ensure that only the last insn modifying
184 a split iv will update the original iv of the dest. */
186 static int *splittable_regs_updates;
188 /* Values describing the current loop's iteration variable. These are set up
189 by loop_iterations, and used by precondition_loop_p. */
191 static rtx loop_iteration_var;
192 static rtx loop_initial_value;
193 static rtx loop_increment;
194 static rtx loop_final_value;
195 static enum rtx_code loop_comparison_code;
197 /* Forward declarations. */
199 static void init_reg_map PROTO((struct inline_remap *, int));
200 static int precondition_loop_p PROTO((rtx *, rtx *, rtx *, rtx, rtx));
201 static rtx calculate_giv_inc PROTO((rtx, rtx, int));
202 static rtx initial_reg_note_copy PROTO((rtx, struct inline_remap *));
203 static void final_reg_note_copy PROTO((rtx, struct inline_remap *));
204 static void copy_loop_body PROTO((rtx, rtx, struct inline_remap *, rtx, int,
205 enum unroll_types, rtx, rtx, rtx, rtx));
206 void iteration_info PROTO((rtx, rtx *, rtx *, rtx, rtx));
207 static rtx approx_final_value PROTO((enum rtx_code, rtx, int *, int *));
208 static int find_splittable_regs PROTO((enum unroll_types, rtx, rtx, rtx, int));
209 static int find_splittable_givs PROTO((struct iv_class *,enum unroll_types,
210 rtx, rtx, rtx, int));
211 static int reg_dead_after_loop PROTO((rtx, rtx, rtx));
212 static rtx fold_rtx_mult_add PROTO((rtx, rtx, rtx, enum machine_mode));
213 static int verify_addresses PROTO((struct induction *, rtx, int));
214 static rtx remap_split_bivs PROTO((rtx));
216 /* Try to unroll one loop and split induction variables in the loop.
218 The loop is described by the arguments LOOP_END, INSN_COUNT, and
219 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
220 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
221 indicates whether information generated in the strength reduction pass
224 This function is intended to be called from within `strength_reduce'
228 unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
233 rtx end_insert_before;
234 int strength_reduce_p;
237 int unroll_number = 1;
238 rtx copy_start, copy_end;
239 rtx insn, sequence, pattern, tem;
240 int max_labelno, max_insnno;
242 struct inline_remap *map;
250 int splitting_not_safe = 0;
251 enum unroll_types unroll_type;
252 int loop_preconditioned = 0;
254 /* This points to the last real insn in the loop, which should be either
255 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
259 /* Don't bother unrolling huge loops. Since the minimum factor is
260 two, loops greater than one half of MAX_UNROLLED_INSNS will never
262 if (insn_count > MAX_UNROLLED_INSNS / 2)
264 if (loop_dump_stream)
265 fprintf (loop_dump_stream, "Unrolling failure: Loop too big.\n");
269 /* When emitting debugger info, we can't unroll loops with unequal numbers
270 of block_beg and block_end notes, because that would unbalance the block
271 structure of the function. This can happen as a result of the
272 "if (foo) bar; else break;" optimization in jump.c. */
273 /* ??? Gcc has a general policy that -g is never supposed to change the code
274 that the compiler emits, so we must disable this optimization always,
275 even if debug info is not being output. This is rare, so this should
276 not be a significant performance problem. */
278 if (1 /* write_symbols != NO_DEBUG */)
280 int block_begins = 0;
283 for (insn = loop_start; insn != loop_end; insn = NEXT_INSN (insn))
285 if (GET_CODE (insn) == NOTE)
287 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
289 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
294 if (block_begins != block_ends)
296 if (loop_dump_stream)
297 fprintf (loop_dump_stream,
298 "Unrolling failure: Unbalanced block notes.\n");
303 /* Determine type of unroll to perform. Depends on the number of iterations
304 and the size of the loop. */
306 /* If there is no strength reduce info, then set loop_n_iterations to zero.
307 This can happen if strength_reduce can't find any bivs in the loop.
308 A value of zero indicates that the number of iterations could not be
311 if (! strength_reduce_p)
312 loop_n_iterations = 0;
314 if (loop_dump_stream && loop_n_iterations > 0)
315 fprintf (loop_dump_stream,
316 "Loop unrolling: %d iterations.\n", loop_n_iterations);
318 /* Find and save a pointer to the last nonnote insn in the loop. */
320 last_loop_insn = prev_nonnote_insn (loop_end);
322 /* Calculate how many times to unroll the loop. Indicate whether or
323 not the loop is being completely unrolled. */
325 if (loop_n_iterations == 1)
327 /* If number of iterations is exactly 1, then eliminate the compare and
328 branch at the end of the loop since they will never be taken.
329 Then return, since no other action is needed here. */
331 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
332 don't do anything. */
334 if (GET_CODE (last_loop_insn) == BARRIER)
336 /* Delete the jump insn. This will delete the barrier also. */
337 delete_insn (PREV_INSN (last_loop_insn));
339 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
342 /* The immediately preceding insn is a compare which must be
344 delete_insn (last_loop_insn);
345 delete_insn (PREV_INSN (last_loop_insn));
347 /* The immediately preceding insn may not be the compare, so don't
349 delete_insn (last_loop_insn);
354 else if (loop_n_iterations > 0
355 && loop_n_iterations * insn_count < MAX_UNROLLED_INSNS)
357 unroll_number = loop_n_iterations;
358 unroll_type = UNROLL_COMPLETELY;
360 else if (loop_n_iterations > 0)
362 /* Try to factor the number of iterations. Don't bother with the
363 general case, only using 2, 3, 5, and 7 will get 75% of all
364 numbers theoretically, and almost all in practice. */
366 for (i = 0; i < NUM_FACTORS; i++)
367 factors[i].count = 0;
369 temp = loop_n_iterations;
370 for (i = NUM_FACTORS - 1; i >= 0; i--)
371 while (temp % factors[i].factor == 0)
374 temp = temp / factors[i].factor;
377 /* Start with the larger factors first so that we generally
378 get lots of unrolling. */
382 for (i = 3; i >= 0; i--)
383 while (factors[i].count--)
385 if (temp * factors[i].factor < MAX_UNROLLED_INSNS)
387 unroll_number *= factors[i].factor;
388 temp *= factors[i].factor;
394 /* If we couldn't find any factors, then unroll as in the normal
396 if (unroll_number == 1)
398 if (loop_dump_stream)
399 fprintf (loop_dump_stream,
400 "Loop unrolling: No factors found.\n");
403 unroll_type = UNROLL_MODULO;
407 /* Default case, calculate number of times to unroll loop based on its
409 if (unroll_number == 1)
411 if (8 * insn_count < MAX_UNROLLED_INSNS)
413 else if (4 * insn_count < MAX_UNROLLED_INSNS)
418 unroll_type = UNROLL_NAIVE;
421 /* Now we know how many times to unroll the loop. */
423 if (loop_dump_stream)
424 fprintf (loop_dump_stream,
425 "Unrolling loop %d times.\n", unroll_number);
428 if (unroll_type == UNROLL_COMPLETELY || unroll_type == UNROLL_MODULO)
430 /* Loops of these types should never start with a jump down to
431 the exit condition test. For now, check for this case just to
432 be sure. UNROLL_NAIVE loops can be of this form, this case is
435 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
436 insn = NEXT_INSN (insn);
437 if (GET_CODE (insn) == JUMP_INSN)
441 if (unroll_type == UNROLL_COMPLETELY)
443 /* Completely unrolling the loop: Delete the compare and branch at
444 the end (the last two instructions). This delete must done at the
445 very end of loop unrolling, to avoid problems with calls to
446 back_branch_in_range_p, which is called by find_splittable_regs.
447 All increments of splittable bivs/givs are changed to load constant
450 copy_start = loop_start;
452 /* Set insert_before to the instruction immediately after the JUMP_INSN
453 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
454 the loop will be correctly handled by copy_loop_body. */
455 insert_before = NEXT_INSN (last_loop_insn);
457 /* Set copy_end to the insn before the jump at the end of the loop. */
458 if (GET_CODE (last_loop_insn) == BARRIER)
459 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
460 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
463 /* The instruction immediately before the JUMP_INSN is a compare
464 instruction which we do not want to copy. */
465 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
467 /* The instruction immediately before the JUMP_INSN may not be the
468 compare, so we must copy it. */
469 copy_end = PREV_INSN (last_loop_insn);
474 /* We currently can't unroll a loop if it doesn't end with a
475 JUMP_INSN. There would need to be a mechanism that recognizes
476 this case, and then inserts a jump after each loop body, which
477 jumps to after the last loop body. */
478 if (loop_dump_stream)
479 fprintf (loop_dump_stream,
480 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
484 else if (unroll_type == UNROLL_MODULO)
486 /* Partially unrolling the loop: The compare and branch at the end
487 (the last two instructions) must remain. Don't copy the compare
488 and branch instructions at the end of the loop. Insert the unrolled
489 code immediately before the compare/branch at the end so that the
490 code will fall through to them as before. */
492 copy_start = loop_start;
494 /* Set insert_before to the jump insn at the end of the loop.
495 Set copy_end to before the jump insn at the end of the loop. */
496 if (GET_CODE (last_loop_insn) == BARRIER)
498 insert_before = PREV_INSN (last_loop_insn);
499 copy_end = PREV_INSN (insert_before);
501 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
504 /* The instruction immediately before the JUMP_INSN is a compare
505 instruction which we do not want to copy or delete. */
506 insert_before = PREV_INSN (last_loop_insn);
507 copy_end = PREV_INSN (insert_before);
509 /* The instruction immediately before the JUMP_INSN may not be the
510 compare, so we must copy it. */
511 insert_before = last_loop_insn;
512 copy_end = PREV_INSN (last_loop_insn);
517 /* We currently can't unroll a loop if it doesn't end with a
518 JUMP_INSN. There would need to be a mechanism that recognizes
519 this case, and then inserts a jump after each loop body, which
520 jumps to after the last loop body. */
521 if (loop_dump_stream)
522 fprintf (loop_dump_stream,
523 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
529 /* Normal case: Must copy the compare and branch instructions at the
532 if (GET_CODE (last_loop_insn) == BARRIER)
534 /* Loop ends with an unconditional jump and a barrier.
535 Handle this like above, don't copy jump and barrier.
536 This is not strictly necessary, but doing so prevents generating
537 unconditional jumps to an immediately following label.
539 This will be corrected below if the target of this jump is
540 not the start_label. */
542 insert_before = PREV_INSN (last_loop_insn);
543 copy_end = PREV_INSN (insert_before);
545 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
547 /* Set insert_before to immediately after the JUMP_INSN, so that
548 NOTEs at the end of the loop will be correctly handled by
550 insert_before = NEXT_INSN (last_loop_insn);
551 copy_end = last_loop_insn;
555 /* We currently can't unroll a loop if it doesn't end with a
556 JUMP_INSN. There would need to be a mechanism that recognizes
557 this case, and then inserts a jump after each loop body, which
558 jumps to after the last loop body. */
559 if (loop_dump_stream)
560 fprintf (loop_dump_stream,
561 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
565 /* If copying exit test branches because they can not be eliminated,
566 then must convert the fall through case of the branch to a jump past
567 the end of the loop. Create a label to emit after the loop and save
568 it for later use. Do not use the label after the loop, if any, since
569 it might be used by insns outside the loop, or there might be insns
570 added before it later by final_[bg]iv_value which must be after
571 the real exit label. */
572 exit_label = gen_label_rtx ();
575 while (GET_CODE (insn) != CODE_LABEL && GET_CODE (insn) != JUMP_INSN)
576 insn = NEXT_INSN (insn);
578 if (GET_CODE (insn) == JUMP_INSN)
580 /* The loop starts with a jump down to the exit condition test.
581 Start copying the loop after the barrier following this
583 copy_start = NEXT_INSN (insn);
585 /* Splitting induction variables doesn't work when the loop is
586 entered via a jump to the bottom, because then we end up doing
587 a comparison against a new register for a split variable, but
588 we did not execute the set insn for the new register because
589 it was skipped over. */
590 splitting_not_safe = 1;
591 if (loop_dump_stream)
592 fprintf (loop_dump_stream,
593 "Splitting not safe, because loop not entered at top.\n");
596 copy_start = loop_start;
599 /* This should always be the first label in the loop. */
600 start_label = NEXT_INSN (copy_start);
601 /* There may be a line number note and/or a loop continue note here. */
602 while (GET_CODE (start_label) == NOTE)
603 start_label = NEXT_INSN (start_label);
604 if (GET_CODE (start_label) != CODE_LABEL)
606 /* This can happen as a result of jump threading. If the first insns in
607 the loop test the same condition as the loop's backward jump, or the
608 opposite condition, then the backward jump will be modified to point
609 to elsewhere, and the loop's start label is deleted.
611 This case currently can not be handled by the loop unrolling code. */
613 if (loop_dump_stream)
614 fprintf (loop_dump_stream,
615 "Unrolling failure: unknown insns between BEG note and loop label.\n");
618 if (LABEL_NAME (start_label))
620 /* The jump optimization pass must have combined the original start label
621 with a named label for a goto. We can't unroll this case because
622 jumps which go to the named label must be handled differently than
623 jumps to the loop start, and it is impossible to differentiate them
625 if (loop_dump_stream)
626 fprintf (loop_dump_stream,
627 "Unrolling failure: loop start label is gone\n");
631 if (unroll_type == UNROLL_NAIVE
632 && GET_CODE (last_loop_insn) == BARRIER
633 && start_label != JUMP_LABEL (PREV_INSN (last_loop_insn)))
635 /* In this case, we must copy the jump and barrier, because they will
636 not be converted to jumps to an immediately following label. */
638 insert_before = NEXT_INSN (last_loop_insn);
639 copy_end = last_loop_insn;
642 if (unroll_type == UNROLL_NAIVE
643 && GET_CODE (last_loop_insn) == JUMP_INSN
644 && start_label != JUMP_LABEL (last_loop_insn))
646 /* ??? The loop ends with a conditional branch that does not branch back
647 to the loop start label. In this case, we must emit an unconditional
648 branch to the loop exit after emitting the final branch.
649 copy_loop_body does not have support for this currently, so we
650 give up. It doesn't seem worthwhile to unroll anyways since
651 unrolling would increase the number of branch instructions
653 if (loop_dump_stream)
654 fprintf (loop_dump_stream,
655 "Unrolling failure: final conditional branch not to loop start\n");
659 /* Allocate a translation table for the labels and insn numbers.
660 They will be filled in as we copy the insns in the loop. */
662 max_labelno = max_label_num ();
663 max_insnno = get_max_uid ();
665 map = (struct inline_remap *) alloca (sizeof (struct inline_remap));
667 map->integrating = 0;
669 /* Allocate the label map. */
673 map->label_map = (rtx *) alloca (max_labelno * sizeof (rtx));
675 local_label = (char *) alloca (max_labelno);
676 bzero (local_label, max_labelno);
681 /* Search the loop and mark all local labels, i.e. the ones which have to
682 be distinct labels when copied. For all labels which might be
683 non-local, set their label_map entries to point to themselves.
684 If they happen to be local their label_map entries will be overwritten
685 before the loop body is copied. The label_map entries for local labels
686 will be set to a different value each time the loop body is copied. */
688 for (insn = copy_start; insn != loop_end; insn = NEXT_INSN (insn))
690 if (GET_CODE (insn) == CODE_LABEL)
691 local_label[CODE_LABEL_NUMBER (insn)] = 1;
692 else if (GET_CODE (insn) == JUMP_INSN)
694 if (JUMP_LABEL (insn))
695 set_label_in_map (map,
696 CODE_LABEL_NUMBER (JUMP_LABEL (insn)),
698 else if (GET_CODE (PATTERN (insn)) == ADDR_VEC
699 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
701 rtx pat = PATTERN (insn);
702 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
703 int len = XVECLEN (pat, diff_vec_p);
706 for (i = 0; i < len; i++)
708 label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
709 set_label_in_map (map,
710 CODE_LABEL_NUMBER (label),
717 /* Allocate space for the insn map. */
719 map->insn_map = (rtx *) alloca (max_insnno * sizeof (rtx));
721 /* Set this to zero, to indicate that we are doing loop unrolling,
722 not function inlining. */
723 map->inline_target = 0;
725 /* The register and constant maps depend on the number of registers
726 present, so the final maps can't be created until after
727 find_splittable_regs is called. However, they are needed for
728 preconditioning, so we create temporary maps when preconditioning
731 /* The preconditioning code may allocate two new pseudo registers. */
732 maxregnum = max_reg_num ();
734 /* Allocate and zero out the splittable_regs and addr_combined_regs
735 arrays. These must be zeroed here because they will be used if
736 loop preconditioning is performed, and must be zero for that case.
738 It is safe to do this here, since the extra registers created by the
739 preconditioning code and find_splittable_regs will never be used
740 to access the splittable_regs[] and addr_combined_regs[] arrays. */
742 splittable_regs = (rtx *) alloca (maxregnum * sizeof (rtx));
743 bzero ((char *) splittable_regs, maxregnum * sizeof (rtx));
744 splittable_regs_updates = (int *) alloca (maxregnum * sizeof (int));
745 bzero ((char *) splittable_regs_updates, maxregnum * sizeof (int));
747 = (struct induction **) alloca (maxregnum * sizeof (struct induction *));
748 bzero ((char *) addr_combined_regs, maxregnum * sizeof (struct induction *));
749 /* We must limit it to max_reg_before_loop, because only these pseudo
750 registers have valid regno_first_uid info. Any register created after
751 that is unlikely to be local to the loop anyways. */
752 local_regno = (char *) alloca (max_reg_before_loop);
753 bzero (local_regno, max_reg_before_loop);
755 /* Mark all local registers, i.e. the ones which are referenced only
757 if (INSN_UID (copy_end) < max_uid_for_loop)
759 int copy_start_luid = INSN_LUID (copy_start);
760 int copy_end_luid = INSN_LUID (copy_end);
762 /* If a register is used in the jump insn, we must not duplicate it
763 since it will also be used outside the loop. */
764 if (GET_CODE (copy_end) == JUMP_INSN)
766 /* If copy_start points to the NOTE that starts the loop, then we must
767 use the next luid, because invariant pseudo-regs moved out of the loop
768 have their lifetimes modified to start here, but they are not safe
770 if (copy_start == loop_start)
773 /* If a pseudo's lifetime is entirely contained within this loop, then we
774 can use a different pseudo in each unrolled copy of the loop. This
775 results in better code. */
776 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; ++j)
777 if (REGNO_FIRST_UID (j) > 0 && REGNO_FIRST_UID (j) <= max_uid_for_loop
778 && uid_luid[REGNO_FIRST_UID (j)] >= copy_start_luid
779 && REGNO_LAST_UID (j) > 0 && REGNO_LAST_UID (j) <= max_uid_for_loop
780 && uid_luid[REGNO_LAST_UID (j)] <= copy_end_luid)
782 /* However, we must also check for loop-carried dependencies.
783 If the value the pseudo has at the end of iteration X is
784 used by iteration X+1, then we can not use a different pseudo
785 for each unrolled copy of the loop. */
786 /* A pseudo is safe if regno_first_uid is a set, and this
787 set dominates all instructions from regno_first_uid to
789 /* ??? This check is simplistic. We would get better code if
790 this check was more sophisticated. */
791 if (set_dominates_use (j, REGNO_FIRST_UID (j), REGNO_LAST_UID (j),
792 copy_start, copy_end))
795 if (loop_dump_stream)
798 fprintf (loop_dump_stream, "Marked reg %d as local\n", j);
800 fprintf (loop_dump_stream, "Did not mark reg %d as local\n",
806 /* If this loop requires exit tests when unrolled, check to see if we
807 can precondition the loop so as to make the exit tests unnecessary.
808 Just like variable splitting, this is not safe if the loop is entered
809 via a jump to the bottom. Also, can not do this if no strength
810 reduce info, because precondition_loop_p uses this info. */
812 /* Must copy the loop body for preconditioning before the following
813 find_splittable_regs call since that will emit insns which need to
814 be after the preconditioned loop copies, but immediately before the
815 unrolled loop copies. */
817 /* Also, it is not safe to split induction variables for the preconditioned
818 copies of the loop body. If we split induction variables, then the code
819 assumes that each induction variable can be represented as a function
820 of its initial value and the loop iteration number. This is not true
821 in this case, because the last preconditioned copy of the loop body
822 could be any iteration from the first up to the `unroll_number-1'th,
823 depending on the initial value of the iteration variable. Therefore
824 we can not split induction variables here, because we can not calculate
825 their value. Hence, this code must occur before find_splittable_regs
828 if (unroll_type == UNROLL_NAIVE && ! splitting_not_safe && strength_reduce_p)
830 rtx initial_value, final_value, increment;
832 if (precondition_loop_p (&initial_value, &final_value, &increment,
833 loop_start, loop_end))
836 enum machine_mode mode;
838 int abs_inc, neg_inc;
840 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
842 map->const_equiv_map = (rtx *) alloca (maxregnum * sizeof (rtx));
843 map->const_age_map = (unsigned *) alloca (maxregnum
844 * sizeof (unsigned));
845 map->const_equiv_map_size = maxregnum;
846 global_const_equiv_map = map->const_equiv_map;
847 global_const_equiv_map_size = maxregnum;
849 init_reg_map (map, maxregnum);
851 /* Limit loop unrolling to 4, since this will make 7 copies of
853 if (unroll_number > 4)
856 /* Save the absolute value of the increment, and also whether or
857 not it is negative. */
859 abs_inc = INTVAL (increment);
868 /* Decide what mode to do these calculations in. Choose the larger
869 of final_value's mode and initial_value's mode, or a full-word if
870 both are constants. */
871 mode = GET_MODE (final_value);
872 if (mode == VOIDmode)
874 mode = GET_MODE (initial_value);
875 if (mode == VOIDmode)
878 else if (mode != GET_MODE (initial_value)
879 && (GET_MODE_SIZE (mode)
880 < GET_MODE_SIZE (GET_MODE (initial_value))))
881 mode = GET_MODE (initial_value);
883 /* Calculate the difference between the final and initial values.
884 Final value may be a (plus (reg x) (const_int 1)) rtx.
885 Let the following cse pass simplify this if initial value is
888 We must copy the final and initial values here to avoid
889 improperly shared rtl. */
891 diff = expand_binop (mode, sub_optab, copy_rtx (final_value),
892 copy_rtx (initial_value), NULL_RTX, 0,
895 /* Now calculate (diff % (unroll * abs (increment))) by using an
897 diff = expand_binop (GET_MODE (diff), and_optab, diff,
898 GEN_INT (unroll_number * abs_inc - 1),
899 NULL_RTX, 0, OPTAB_LIB_WIDEN);
901 /* Now emit a sequence of branches to jump to the proper precond
904 labels = (rtx *) alloca (sizeof (rtx) * unroll_number);
905 for (i = 0; i < unroll_number; i++)
906 labels[i] = gen_label_rtx ();
908 /* Check for the case where the initial value is greater than or
909 equal to the final value. In that case, we want to execute
910 exactly one loop iteration. The code below will fail for this
911 case. This check does not apply if the loop has a NE
912 comparison at the end. */
914 if (loop_comparison_code != NE)
916 emit_cmp_insn (initial_value, final_value, neg_inc ? LE : GE,
917 NULL_RTX, mode, 0, 0);
919 emit_jump_insn (gen_ble (labels[1]));
921 emit_jump_insn (gen_bge (labels[1]));
922 JUMP_LABEL (get_last_insn ()) = labels[1];
923 LABEL_NUSES (labels[1])++;
926 /* Assuming the unroll_number is 4, and the increment is 2, then
927 for a negative increment: for a positive increment:
928 diff = 0,1 precond 0 diff = 0,7 precond 0
929 diff = 2,3 precond 3 diff = 1,2 precond 1
930 diff = 4,5 precond 2 diff = 3,4 precond 2
931 diff = 6,7 precond 1 diff = 5,6 precond 3 */
933 /* We only need to emit (unroll_number - 1) branches here, the
934 last case just falls through to the following code. */
936 /* ??? This would give better code if we emitted a tree of branches
937 instead of the current linear list of branches. */
939 for (i = 0; i < unroll_number - 1; i++)
942 enum rtx_code cmp_code;
944 /* For negative increments, must invert the constant compared
945 against, except when comparing against zero. */
953 cmp_const = unroll_number - i;
962 emit_cmp_insn (diff, GEN_INT (abs_inc * cmp_const),
963 cmp_code, NULL_RTX, mode, 0, 0);
966 emit_jump_insn (gen_beq (labels[i]));
968 emit_jump_insn (gen_bge (labels[i]));
970 emit_jump_insn (gen_ble (labels[i]));
971 JUMP_LABEL (get_last_insn ()) = labels[i];
972 LABEL_NUSES (labels[i])++;
975 /* If the increment is greater than one, then we need another branch,
976 to handle other cases equivalent to 0. */
978 /* ??? This should be merged into the code above somehow to help
979 simplify the code here, and reduce the number of branches emitted.
980 For the negative increment case, the branch here could easily
981 be merged with the `0' case branch above. For the positive
982 increment case, it is not clear how this can be simplified. */
987 enum rtx_code cmp_code;
991 cmp_const = abs_inc - 1;
996 cmp_const = abs_inc * (unroll_number - 1) + 1;
1000 emit_cmp_insn (diff, GEN_INT (cmp_const), cmp_code, NULL_RTX,
1004 emit_jump_insn (gen_ble (labels[0]));
1006 emit_jump_insn (gen_bge (labels[0]));
1007 JUMP_LABEL (get_last_insn ()) = labels[0];
1008 LABEL_NUSES (labels[0])++;
1011 sequence = gen_sequence ();
1013 emit_insn_before (sequence, loop_start);
1015 /* Only the last copy of the loop body here needs the exit
1016 test, so set copy_end to exclude the compare/branch here,
1017 and then reset it inside the loop when get to the last
1020 if (GET_CODE (last_loop_insn) == BARRIER)
1021 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1022 else if (GET_CODE (last_loop_insn) == JUMP_INSN)
1025 /* The immediately preceding insn is a compare which we do not
1027 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1029 /* The immediately preceding insn may not be a compare, so we
1031 copy_end = PREV_INSN (last_loop_insn);
1037 for (i = 1; i < unroll_number; i++)
1039 emit_label_after (labels[unroll_number - i],
1040 PREV_INSN (loop_start));
1042 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1043 bzero ((char *) map->const_equiv_map, maxregnum * sizeof (rtx));
1044 bzero ((char *) map->const_age_map,
1045 maxregnum * sizeof (unsigned));
1048 for (j = 0; j < max_labelno; j++)
1050 set_label_in_map (map, j, gen_label_rtx ());
1052 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; j++)
1055 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1056 record_base_value (REGNO (map->reg_map[j]),
1057 regno_reg_rtx[j], 0);
1059 /* The last copy needs the compare/branch insns at the end,
1060 so reset copy_end here if the loop ends with a conditional
1063 if (i == unroll_number - 1)
1065 if (GET_CODE (last_loop_insn) == BARRIER)
1066 copy_end = PREV_INSN (PREV_INSN (last_loop_insn));
1068 copy_end = last_loop_insn;
1071 /* None of the copies are the `last_iteration', so just
1072 pass zero for that parameter. */
1073 copy_loop_body (copy_start, copy_end, map, exit_label, 0,
1074 unroll_type, start_label, loop_end,
1075 loop_start, copy_end);
1077 emit_label_after (labels[0], PREV_INSN (loop_start));
1079 if (GET_CODE (last_loop_insn) == BARRIER)
1081 insert_before = PREV_INSN (last_loop_insn);
1082 copy_end = PREV_INSN (insert_before);
1087 /* The immediately preceding insn is a compare which we do not
1089 insert_before = PREV_INSN (last_loop_insn);
1090 copy_end = PREV_INSN (insert_before);
1092 /* The immediately preceding insn may not be a compare, so we
1094 insert_before = last_loop_insn;
1095 copy_end = PREV_INSN (last_loop_insn);
1099 /* Set unroll type to MODULO now. */
1100 unroll_type = UNROLL_MODULO;
1101 loop_preconditioned = 1;
1104 /* Fix the initial value for the loop as needed. */
1105 if (loop_n_iterations <= 0)
1106 loop_start_value [uid_loop_num [INSN_UID (loop_start)]]
1112 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1113 the loop unless all loops are being unrolled. */
1114 if (unroll_type == UNROLL_NAIVE && ! flag_unroll_all_loops)
1116 if (loop_dump_stream)
1117 fprintf (loop_dump_stream, "Unrolling failure: Naive unrolling not being done.\n");
1121 /* At this point, we are guaranteed to unroll the loop. */
1123 /* Keep track of the unroll factor for each loop. */
1124 if (unroll_type == UNROLL_COMPLETELY)
1125 loop_unroll_factor [uid_loop_num [INSN_UID (loop_start)]] = -1;
1127 loop_unroll_factor [uid_loop_num [INSN_UID (loop_start)]] = unroll_number;
1130 /* For each biv and giv, determine whether it can be safely split into
1131 a different variable for each unrolled copy of the loop body.
1132 We precalculate and save this info here, since computing it is
1135 Do this before deleting any instructions from the loop, so that
1136 back_branch_in_range_p will work correctly. */
1138 if (splitting_not_safe)
1141 temp = find_splittable_regs (unroll_type, loop_start, loop_end,
1142 end_insert_before, unroll_number);
1144 /* find_splittable_regs may have created some new registers, so must
1145 reallocate the reg_map with the new larger size, and must realloc
1146 the constant maps also. */
1148 maxregnum = max_reg_num ();
1149 map->reg_map = (rtx *) alloca (maxregnum * sizeof (rtx));
1151 init_reg_map (map, maxregnum);
1153 /* Space is needed in some of the map for new registers, so new_maxregnum
1154 is an (over)estimate of how many registers will exist at the end. */
1155 new_maxregnum = maxregnum + (temp * unroll_number * 2);
1157 /* Must realloc space for the constant maps, because the number of registers
1158 may have changed. */
1160 map->const_equiv_map = (rtx *) alloca (new_maxregnum * sizeof (rtx));
1161 map->const_age_map = (unsigned *) alloca (new_maxregnum * sizeof (unsigned));
1163 map->const_equiv_map_size = new_maxregnum;
1164 global_const_equiv_map = map->const_equiv_map;
1165 global_const_equiv_map_size = new_maxregnum;
1167 /* Search the list of bivs and givs to find ones which need to be remapped
1168 when split, and set their reg_map entry appropriately. */
1170 for (bl = loop_iv_list; bl; bl = bl->next)
1172 if (REGNO (bl->biv->src_reg) != bl->regno)
1173 map->reg_map[bl->regno] = bl->biv->src_reg;
1175 /* Currently, non-reduced/final-value givs are never split. */
1176 for (v = bl->giv; v; v = v->next_iv)
1177 if (REGNO (v->src_reg) != bl->regno)
1178 map->reg_map[REGNO (v->dest_reg)] = v->src_reg;
1182 /* Use our current register alignment and pointer flags. */
1183 map->regno_pointer_flag = regno_pointer_flag;
1184 map->regno_pointer_align = regno_pointer_align;
1186 /* If the loop is being partially unrolled, and the iteration variables
1187 are being split, and are being renamed for the split, then must fix up
1188 the compare/jump instruction at the end of the loop to refer to the new
1189 registers. This compare isn't copied, so the registers used in it
1190 will never be replaced if it isn't done here. */
1192 if (unroll_type == UNROLL_MODULO)
1194 insn = NEXT_INSN (copy_end);
1195 if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
1196 PATTERN (insn) = remap_split_bivs (PATTERN (insn));
1199 /* For unroll_number - 1 times, make a copy of each instruction
1200 between copy_start and copy_end, and insert these new instructions
1201 before the end of the loop. */
1203 for (i = 0; i < unroll_number; i++)
1205 bzero ((char *) map->insn_map, max_insnno * sizeof (rtx));
1206 bzero ((char *) map->const_equiv_map, new_maxregnum * sizeof (rtx));
1207 bzero ((char *) map->const_age_map, new_maxregnum * sizeof (unsigned));
1210 for (j = 0; j < max_labelno; j++)
1212 set_label_in_map (map, j, gen_label_rtx ());
1214 for (j = FIRST_PSEUDO_REGISTER; j < max_reg_before_loop; j++)
1217 map->reg_map[j] = gen_reg_rtx (GET_MODE (regno_reg_rtx[j]));
1218 record_base_value (REGNO (map->reg_map[j]),
1219 regno_reg_rtx[j], 0);
1222 /* If loop starts with a branch to the test, then fix it so that
1223 it points to the test of the first unrolled copy of the loop. */
1224 if (i == 0 && loop_start != copy_start)
1226 insn = PREV_INSN (copy_start);
1227 pattern = PATTERN (insn);
1229 tem = get_label_from_map (map,
1231 (XEXP (SET_SRC (pattern), 0)));
1232 SET_SRC (pattern) = gen_rtx_LABEL_REF (VOIDmode, tem);
1234 /* Set the jump label so that it can be used by later loop unrolling
1236 JUMP_LABEL (insn) = tem;
1237 LABEL_NUSES (tem)++;
1240 copy_loop_body (copy_start, copy_end, map, exit_label,
1241 i == unroll_number - 1, unroll_type, start_label,
1242 loop_end, insert_before, insert_before);
1245 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1246 insn to be deleted. This prevents any runaway delete_insn call from
1247 more insns that it should, as it always stops at a CODE_LABEL. */
1249 /* Delete the compare and branch at the end of the loop if completely
1250 unrolling the loop. Deleting the backward branch at the end also
1251 deletes the code label at the start of the loop. This is done at
1252 the very end to avoid problems with back_branch_in_range_p. */
1254 if (unroll_type == UNROLL_COMPLETELY)
1255 safety_label = emit_label_after (gen_label_rtx (), last_loop_insn);
1257 safety_label = emit_label_after (gen_label_rtx (), copy_end);
1259 /* Delete all of the original loop instructions. Don't delete the
1260 LOOP_BEG note, or the first code label in the loop. */
1262 insn = NEXT_INSN (copy_start);
1263 while (insn != safety_label)
1265 if (insn != start_label)
1266 insn = delete_insn (insn);
1268 insn = NEXT_INSN (insn);
1271 /* Can now delete the 'safety' label emitted to protect us from runaway
1272 delete_insn calls. */
1273 if (INSN_DELETED_P (safety_label))
1275 delete_insn (safety_label);
1277 /* If exit_label exists, emit it after the loop. Doing the emit here
1278 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1279 This is needed so that mostly_true_jump in reorg.c will treat jumps
1280 to this loop end label correctly, i.e. predict that they are usually
1283 emit_label_after (exit_label, loop_end);
1286 /* Return true if the loop can be safely, and profitably, preconditioned
1287 so that the unrolled copies of the loop body don't need exit tests.
1289 This only works if final_value, initial_value and increment can be
1290 determined, and if increment is a constant power of 2.
1291 If increment is not a power of 2, then the preconditioning modulo
1292 operation would require a real modulo instead of a boolean AND, and this
1293 is not considered `profitable'. */
1295 /* ??? If the loop is known to be executed very many times, or the machine
1296 has a very cheap divide instruction, then preconditioning is a win even
1297 when the increment is not a power of 2. Use RTX_COST to compute
1298 whether divide is cheap. */
1301 precondition_loop_p (initial_value, final_value, increment, loop_start,
1303 rtx *initial_value, *final_value, *increment;
1304 rtx loop_start, loop_end;
1307 if (loop_n_iterations > 0)
1309 *initial_value = const0_rtx;
1310 *increment = const1_rtx;
1311 *final_value = GEN_INT (loop_n_iterations);
1313 if (loop_dump_stream)
1314 fprintf (loop_dump_stream,
1315 "Preconditioning: Success, number of iterations known, %d.\n",
1320 if (loop_initial_value == 0)
1322 if (loop_dump_stream)
1323 fprintf (loop_dump_stream,
1324 "Preconditioning: Could not find initial value.\n");
1327 else if (loop_increment == 0)
1329 if (loop_dump_stream)
1330 fprintf (loop_dump_stream,
1331 "Preconditioning: Could not find increment value.\n");
1334 else if (GET_CODE (loop_increment) != CONST_INT)
1336 if (loop_dump_stream)
1337 fprintf (loop_dump_stream,
1338 "Preconditioning: Increment not a constant.\n");
1341 else if ((exact_log2 (INTVAL (loop_increment)) < 0)
1342 && (exact_log2 (- INTVAL (loop_increment)) < 0))
1344 if (loop_dump_stream)
1345 fprintf (loop_dump_stream,
1346 "Preconditioning: Increment not a constant power of 2.\n");
1350 /* Unsigned_compare and compare_dir can be ignored here, since they do
1351 not matter for preconditioning. */
1353 if (loop_final_value == 0)
1355 if (loop_dump_stream)
1356 fprintf (loop_dump_stream,
1357 "Preconditioning: EQ comparison loop.\n");
1361 /* Must ensure that final_value is invariant, so call invariant_p to
1362 check. Before doing so, must check regno against max_reg_before_loop
1363 to make sure that the register is in the range covered by invariant_p.
1364 If it isn't, then it is most likely a biv/giv which by definition are
1366 if ((GET_CODE (loop_final_value) == REG
1367 && REGNO (loop_final_value) >= max_reg_before_loop)
1368 || (GET_CODE (loop_final_value) == PLUS
1369 && REGNO (XEXP (loop_final_value, 0)) >= max_reg_before_loop)
1370 || ! invariant_p (loop_final_value))
1372 if (loop_dump_stream)
1373 fprintf (loop_dump_stream,
1374 "Preconditioning: Final value not invariant.\n");
1378 /* Fail for floating point values, since the caller of this function
1379 does not have code to deal with them. */
1380 if (GET_MODE_CLASS (GET_MODE (loop_final_value)) == MODE_FLOAT
1381 || GET_MODE_CLASS (GET_MODE (loop_initial_value)) == MODE_FLOAT)
1383 if (loop_dump_stream)
1384 fprintf (loop_dump_stream,
1385 "Preconditioning: Floating point final or initial value.\n");
1389 /* Now set initial_value to be the iteration_var, since that may be a
1390 simpler expression, and is guaranteed to be correct if all of the
1391 above tests succeed.
1393 We can not use the initial_value as calculated, because it will be
1394 one too small for loops of the form "while (i-- > 0)". We can not
1395 emit code before the loop_skip_over insns to fix this problem as this
1396 will then give a number one too large for loops of the form
1399 Note that all loops that reach here are entered at the top, because
1400 this function is not called if the loop starts with a jump. */
1402 /* Fail if loop_iteration_var is not live before loop_start, since we need
1403 to test its value in the preconditioning code. */
1405 if (uid_luid[REGNO_FIRST_UID (REGNO (loop_iteration_var))]
1406 > INSN_LUID (loop_start))
1408 if (loop_dump_stream)
1409 fprintf (loop_dump_stream,
1410 "Preconditioning: Iteration var not live before loop start.\n");
1414 *initial_value = loop_iteration_var;
1415 *increment = loop_increment;
1416 *final_value = loop_final_value;
1419 if (loop_dump_stream)
1420 fprintf (loop_dump_stream, "Preconditioning: Successful.\n");
1425 /* All pseudo-registers must be mapped to themselves. Two hard registers
1426 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1427 REGNUM, to avoid function-inlining specific conversions of these
1428 registers. All other hard regs can not be mapped because they may be
1433 init_reg_map (map, maxregnum)
1434 struct inline_remap *map;
1439 for (i = maxregnum - 1; i > LAST_VIRTUAL_REGISTER; i--)
1440 map->reg_map[i] = regno_reg_rtx[i];
1441 /* Just clear the rest of the entries. */
1442 for (i = LAST_VIRTUAL_REGISTER; i >= 0; i--)
1443 map->reg_map[i] = 0;
1445 map->reg_map[VIRTUAL_STACK_VARS_REGNUM]
1446 = regno_reg_rtx[VIRTUAL_STACK_VARS_REGNUM];
1447 map->reg_map[VIRTUAL_INCOMING_ARGS_REGNUM]
1448 = regno_reg_rtx[VIRTUAL_INCOMING_ARGS_REGNUM];
1451 /* Strength-reduction will often emit code for optimized biv/givs which
1452 calculates their value in a temporary register, and then copies the result
1453 to the iv. This procedure reconstructs the pattern computing the iv;
1454 verifying that all operands are of the proper form.
1456 PATTERN must be the result of single_set.
1457 The return value is the amount that the giv is incremented by. */
1460 calculate_giv_inc (pattern, src_insn, regno)
1461 rtx pattern, src_insn;
1465 rtx increment_total = 0;
1469 /* Verify that we have an increment insn here. First check for a plus
1470 as the set source. */
1471 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1473 /* SR sometimes computes the new giv value in a temp, then copies it
1475 src_insn = PREV_INSN (src_insn);
1476 pattern = PATTERN (src_insn);
1477 if (GET_CODE (SET_SRC (pattern)) != PLUS)
1480 /* The last insn emitted is not needed, so delete it to avoid confusing
1481 the second cse pass. This insn sets the giv unnecessarily. */
1482 delete_insn (get_last_insn ());
1485 /* Verify that we have a constant as the second operand of the plus. */
1486 increment = XEXP (SET_SRC (pattern), 1);
1487 if (GET_CODE (increment) != CONST_INT)
1489 /* SR sometimes puts the constant in a register, especially if it is
1490 too big to be an add immed operand. */
1491 src_insn = PREV_INSN (src_insn);
1492 increment = SET_SRC (PATTERN (src_insn));
1494 /* SR may have used LO_SUM to compute the constant if it is too large
1495 for a load immed operand. In this case, the constant is in operand
1496 one of the LO_SUM rtx. */
1497 if (GET_CODE (increment) == LO_SUM)
1498 increment = XEXP (increment, 1);
1500 /* Some ports store large constants in memory and add a REG_EQUAL
1501 note to the store insn. */
1502 else if (GET_CODE (increment) == MEM)
1504 rtx note = find_reg_note (src_insn, REG_EQUAL, 0);
1506 increment = XEXP (note, 0);
1509 else if (GET_CODE (increment) == IOR
1510 || GET_CODE (increment) == ASHIFT
1511 || GET_CODE (increment) == PLUS)
1513 /* The rs6000 port loads some constants with IOR.
1514 The alpha port loads some constants with ASHIFT and PLUS. */
1515 rtx second_part = XEXP (increment, 1);
1516 enum rtx_code code = GET_CODE (increment);
1518 src_insn = PREV_INSN (src_insn);
1519 increment = SET_SRC (PATTERN (src_insn));
1520 /* Don't need the last insn anymore. */
1521 delete_insn (get_last_insn ());
1523 if (GET_CODE (second_part) != CONST_INT
1524 || GET_CODE (increment) != CONST_INT)
1528 increment = GEN_INT (INTVAL (increment) | INTVAL (second_part));
1529 else if (code == PLUS)
1530 increment = GEN_INT (INTVAL (increment) + INTVAL (second_part));
1532 increment = GEN_INT (INTVAL (increment) << INTVAL (second_part));
1535 if (GET_CODE (increment) != CONST_INT)
1538 /* The insn loading the constant into a register is no longer needed,
1540 delete_insn (get_last_insn ());
1543 if (increment_total)
1544 increment_total = GEN_INT (INTVAL (increment_total) + INTVAL (increment));
1546 increment_total = increment;
1548 /* Check that the source register is the same as the register we expected
1549 to see as the source. If not, something is seriously wrong. */
1550 if (GET_CODE (XEXP (SET_SRC (pattern), 0)) != REG
1551 || REGNO (XEXP (SET_SRC (pattern), 0)) != regno)
1553 /* Some machines (e.g. the romp), may emit two add instructions for
1554 certain constants, so lets try looking for another add immediately
1555 before this one if we have only seen one add insn so far. */
1561 src_insn = PREV_INSN (src_insn);
1562 pattern = PATTERN (src_insn);
1564 delete_insn (get_last_insn ());
1572 return increment_total;
1575 /* Copy REG_NOTES, except for insn references, because not all insn_map
1576 entries are valid yet. We do need to copy registers now though, because
1577 the reg_map entries can change during copying. */
1580 initial_reg_note_copy (notes, map)
1582 struct inline_remap *map;
1589 copy = rtx_alloc (GET_CODE (notes));
1590 PUT_MODE (copy, GET_MODE (notes));
1592 if (GET_CODE (notes) == EXPR_LIST)
1593 XEXP (copy, 0) = copy_rtx_and_substitute (XEXP (notes, 0), map);
1594 else if (GET_CODE (notes) == INSN_LIST)
1595 /* Don't substitute for these yet. */
1596 XEXP (copy, 0) = XEXP (notes, 0);
1600 XEXP (copy, 1) = initial_reg_note_copy (XEXP (notes, 1), map);
1605 /* Fixup insn references in copied REG_NOTES. */
1608 final_reg_note_copy (notes, map)
1610 struct inline_remap *map;
1614 for (note = notes; note; note = XEXP (note, 1))
1615 if (GET_CODE (note) == INSN_LIST)
1616 XEXP (note, 0) = map->insn_map[INSN_UID (XEXP (note, 0))];
1619 /* Copy each instruction in the loop, substituting from map as appropriate.
1620 This is very similar to a loop in expand_inline_function. */
1623 copy_loop_body (copy_start, copy_end, map, exit_label, last_iteration,
1624 unroll_type, start_label, loop_end, insert_before,
1626 rtx copy_start, copy_end;
1627 struct inline_remap *map;
1630 enum unroll_types unroll_type;
1631 rtx start_label, loop_end, insert_before, copy_notes_from;
1635 int dest_reg_was_split, i;
1639 rtx final_label = 0;
1640 rtx giv_inc, giv_dest_reg, giv_src_reg;
1642 /* If this isn't the last iteration, then map any references to the
1643 start_label to final_label. Final label will then be emitted immediately
1644 after the end of this loop body if it was ever used.
1646 If this is the last iteration, then map references to the start_label
1648 if (! last_iteration)
1650 final_label = gen_label_rtx ();
1651 set_label_in_map (map, CODE_LABEL_NUMBER (start_label),
1655 set_label_in_map (map, CODE_LABEL_NUMBER (start_label), start_label);
1662 insn = NEXT_INSN (insn);
1664 map->orig_asm_operands_vector = 0;
1666 switch (GET_CODE (insn))
1669 pattern = PATTERN (insn);
1673 /* Check to see if this is a giv that has been combined with
1674 some split address givs. (Combined in the sense that
1675 `combine_givs' in loop.c has put two givs in the same register.)
1676 In this case, we must search all givs based on the same biv to
1677 find the address givs. Then split the address givs.
1678 Do this before splitting the giv, since that may map the
1679 SET_DEST to a new register. */
1681 if ((set = single_set (insn))
1682 && GET_CODE (SET_DEST (set)) == REG
1683 && addr_combined_regs[REGNO (SET_DEST (set))])
1685 struct iv_class *bl;
1686 struct induction *v, *tv;
1687 int regno = REGNO (SET_DEST (set));
1689 v = addr_combined_regs[REGNO (SET_DEST (set))];
1690 bl = reg_biv_class[REGNO (v->src_reg)];
1692 /* Although the giv_inc amount is not needed here, we must call
1693 calculate_giv_inc here since it might try to delete the
1694 last insn emitted. If we wait until later to call it,
1695 we might accidentally delete insns generated immediately
1696 below by emit_unrolled_add. */
1698 giv_inc = calculate_giv_inc (set, insn, regno);
1700 /* Now find all address giv's that were combined with this
1702 for (tv = bl->giv; tv; tv = tv->next_iv)
1703 if (tv->giv_type == DEST_ADDR && tv->same == v)
1707 /* If this DEST_ADDR giv was not split, then ignore it. */
1708 if (*tv->location != tv->dest_reg)
1711 /* Scale this_giv_inc if the multiplicative factors of
1712 the two givs are different. */
1713 this_giv_inc = INTVAL (giv_inc);
1714 if (tv->mult_val != v->mult_val)
1715 this_giv_inc = (this_giv_inc / INTVAL (v->mult_val)
1716 * INTVAL (tv->mult_val));
1718 tv->dest_reg = plus_constant (tv->dest_reg, this_giv_inc);
1719 *tv->location = tv->dest_reg;
1721 if (last_iteration && unroll_type != UNROLL_COMPLETELY)
1723 /* Must emit an insn to increment the split address
1724 giv. Add in the const_adjust field in case there
1725 was a constant eliminated from the address. */
1726 rtx value, dest_reg;
1728 /* tv->dest_reg will be either a bare register,
1729 or else a register plus a constant. */
1730 if (GET_CODE (tv->dest_reg) == REG)
1731 dest_reg = tv->dest_reg;
1733 dest_reg = XEXP (tv->dest_reg, 0);
1735 /* Check for shared address givs, and avoid
1736 incrementing the shared pseudo reg more than
1738 if (! tv->same_insn && ! tv->shared)
1740 /* tv->dest_reg may actually be a (PLUS (REG)
1741 (CONST)) here, so we must call plus_constant
1742 to add the const_adjust amount before calling
1743 emit_unrolled_add below. */
1744 value = plus_constant (tv->dest_reg,
1747 /* The constant could be too large for an add
1748 immediate, so can't directly emit an insn
1750 emit_unrolled_add (dest_reg, XEXP (value, 0),
1754 /* Reset the giv to be just the register again, in case
1755 it is used after the set we have just emitted.
1756 We must subtract the const_adjust factor added in
1758 tv->dest_reg = plus_constant (dest_reg,
1759 - tv->const_adjust);
1760 *tv->location = tv->dest_reg;
1765 /* If this is a setting of a splittable variable, then determine
1766 how to split the variable, create a new set based on this split,
1767 and set up the reg_map so that later uses of the variable will
1768 use the new split variable. */
1770 dest_reg_was_split = 0;
1772 if ((set = single_set (insn))
1773 && GET_CODE (SET_DEST (set)) == REG
1774 && splittable_regs[REGNO (SET_DEST (set))])
1776 int regno = REGNO (SET_DEST (set));
1778 dest_reg_was_split = 1;
1780 /* Compute the increment value for the giv, if it wasn't
1781 already computed above. */
1784 giv_inc = calculate_giv_inc (set, insn, regno);
1785 giv_dest_reg = SET_DEST (set);
1786 giv_src_reg = SET_DEST (set);
1788 if (unroll_type == UNROLL_COMPLETELY)
1790 /* Completely unrolling the loop. Set the induction
1791 variable to a known constant value. */
1793 /* The value in splittable_regs may be an invariant
1794 value, so we must use plus_constant here. */
1795 splittable_regs[regno]
1796 = plus_constant (splittable_regs[regno], INTVAL (giv_inc));
1798 if (GET_CODE (splittable_regs[regno]) == PLUS)
1800 giv_src_reg = XEXP (splittable_regs[regno], 0);
1801 giv_inc = XEXP (splittable_regs[regno], 1);
1805 /* The splittable_regs value must be a REG or a
1806 CONST_INT, so put the entire value in the giv_src_reg
1808 giv_src_reg = splittable_regs[regno];
1809 giv_inc = const0_rtx;
1814 /* Partially unrolling loop. Create a new pseudo
1815 register for the iteration variable, and set it to
1816 be a constant plus the original register. Except
1817 on the last iteration, when the result has to
1818 go back into the original iteration var register. */
1820 /* Handle bivs which must be mapped to a new register
1821 when split. This happens for bivs which need their
1822 final value set before loop entry. The new register
1823 for the biv was stored in the biv's first struct
1824 induction entry by find_splittable_regs. */
1826 if (regno < max_reg_before_loop
1827 && reg_iv_type[regno] == BASIC_INDUCT)
1829 giv_src_reg = reg_biv_class[regno]->biv->src_reg;
1830 giv_dest_reg = giv_src_reg;
1834 /* If non-reduced/final-value givs were split, then
1835 this would have to remap those givs also. See
1836 find_splittable_regs. */
1839 splittable_regs[regno]
1840 = GEN_INT (INTVAL (giv_inc)
1841 + INTVAL (splittable_regs[regno]));
1842 giv_inc = splittable_regs[regno];
1844 /* Now split the induction variable by changing the dest
1845 of this insn to a new register, and setting its
1846 reg_map entry to point to this new register.
1848 If this is the last iteration, and this is the last insn
1849 that will update the iv, then reuse the original dest,
1850 to ensure that the iv will have the proper value when
1851 the loop exits or repeats.
1853 Using splittable_regs_updates here like this is safe,
1854 because it can only be greater than one if all
1855 instructions modifying the iv are always executed in
1858 if (! last_iteration
1859 || (splittable_regs_updates[regno]-- != 1))
1861 tem = gen_reg_rtx (GET_MODE (giv_src_reg));
1863 map->reg_map[regno] = tem;
1864 record_base_value (REGNO (tem),
1865 giv_inc == const0_rtx
1867 : gen_rtx_PLUS (GET_MODE (giv_src_reg),
1868 giv_src_reg, giv_inc),
1872 map->reg_map[regno] = giv_src_reg;
1875 /* The constant being added could be too large for an add
1876 immediate, so can't directly emit an insn here. */
1877 emit_unrolled_add (giv_dest_reg, giv_src_reg, giv_inc);
1878 copy = get_last_insn ();
1879 pattern = PATTERN (copy);
1883 pattern = copy_rtx_and_substitute (pattern, map);
1884 copy = emit_insn (pattern);
1886 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1889 /* If this insn is setting CC0, it may need to look at
1890 the insn that uses CC0 to see what type of insn it is.
1891 In that case, the call to recog via validate_change will
1892 fail. So don't substitute constants here. Instead,
1893 do it when we emit the following insn.
1895 For example, see the pyr.md file. That machine has signed and
1896 unsigned compares. The compare patterns must check the
1897 following branch insn to see which what kind of compare to
1900 If the previous insn set CC0, substitute constants on it as
1902 if (sets_cc0_p (PATTERN (copy)) != 0)
1907 try_constants (cc0_insn, map);
1909 try_constants (copy, map);
1912 try_constants (copy, map);
1915 /* Make split induction variable constants `permanent' since we
1916 know there are no backward branches across iteration variable
1917 settings which would invalidate this. */
1918 if (dest_reg_was_split)
1920 int regno = REGNO (SET_DEST (pattern));
1922 if (regno < map->const_equiv_map_size
1923 && map->const_age_map[regno] == map->const_age)
1924 map->const_age_map[regno] = -1;
1929 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
1930 copy = emit_jump_insn (pattern);
1931 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
1933 if (JUMP_LABEL (insn) == start_label && insn == copy_end
1934 && ! last_iteration)
1936 /* This is a branch to the beginning of the loop; this is the
1937 last insn being copied; and this is not the last iteration.
1938 In this case, we want to change the original fall through
1939 case to be a branch past the end of the loop, and the
1940 original jump label case to fall_through. */
1942 if (invert_exp (pattern, copy))
1944 if (! redirect_exp (&pattern,
1945 get_label_from_map (map,
1947 (JUMP_LABEL (insn))),
1954 rtx lab = gen_label_rtx ();
1955 /* Can't do it by reversing the jump (probably because we
1956 couldn't reverse the conditions), so emit a new
1957 jump_insn after COPY, and redirect the jump around
1959 jmp = emit_jump_insn_after (gen_jump (exit_label), copy);
1960 jmp = emit_barrier_after (jmp);
1961 emit_label_after (lab, jmp);
1962 LABEL_NUSES (lab) = 0;
1963 if (! redirect_exp (&pattern,
1964 get_label_from_map (map,
1966 (JUMP_LABEL (insn))),
1974 try_constants (cc0_insn, map);
1977 try_constants (copy, map);
1979 /* Set the jump label of COPY correctly to avoid problems with
1980 later passes of unroll_loop, if INSN had jump label set. */
1981 if (JUMP_LABEL (insn))
1985 /* Can't use the label_map for every insn, since this may be
1986 the backward branch, and hence the label was not mapped. */
1987 if ((set = single_set (copy)))
1989 tem = SET_SRC (set);
1990 if (GET_CODE (tem) == LABEL_REF)
1991 label = XEXP (tem, 0);
1992 else if (GET_CODE (tem) == IF_THEN_ELSE)
1994 if (XEXP (tem, 1) != pc_rtx)
1995 label = XEXP (XEXP (tem, 1), 0);
1997 label = XEXP (XEXP (tem, 2), 0);
2001 if (label && GET_CODE (label) == CODE_LABEL)
2002 JUMP_LABEL (copy) = label;
2005 /* An unrecognizable jump insn, probably the entry jump
2006 for a switch statement. This label must have been mapped,
2007 so just use the label_map to get the new jump label. */
2009 = get_label_from_map (map,
2010 CODE_LABEL_NUMBER (JUMP_LABEL (insn)));
2013 /* If this is a non-local jump, then must increase the label
2014 use count so that the label will not be deleted when the
2015 original jump is deleted. */
2016 LABEL_NUSES (JUMP_LABEL (copy))++;
2018 else if (GET_CODE (PATTERN (copy)) == ADDR_VEC
2019 || GET_CODE (PATTERN (copy)) == ADDR_DIFF_VEC)
2021 rtx pat = PATTERN (copy);
2022 int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
2023 int len = XVECLEN (pat, diff_vec_p);
2026 for (i = 0; i < len; i++)
2027 LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))++;
2030 /* If this used to be a conditional jump insn but whose branch
2031 direction is now known, we must do something special. */
2032 if (condjump_p (insn) && !simplejump_p (insn) && map->last_pc_value)
2035 /* The previous insn set cc0 for us. So delete it. */
2036 delete_insn (PREV_INSN (copy));
2039 /* If this is now a no-op, delete it. */
2040 if (map->last_pc_value == pc_rtx)
2042 /* Don't let delete_insn delete the label referenced here,
2043 because we might possibly need it later for some other
2044 instruction in the loop. */
2045 if (JUMP_LABEL (copy))
2046 LABEL_NUSES (JUMP_LABEL (copy))++;
2048 if (JUMP_LABEL (copy))
2049 LABEL_NUSES (JUMP_LABEL (copy))--;
2053 /* Otherwise, this is unconditional jump so we must put a
2054 BARRIER after it. We could do some dead code elimination
2055 here, but jump.c will do it just as well. */
2061 pattern = copy_rtx_and_substitute (PATTERN (insn), map);
2062 copy = emit_call_insn (pattern);
2063 REG_NOTES (copy) = initial_reg_note_copy (REG_NOTES (insn), map);
2065 /* Because the USAGE information potentially contains objects other
2066 than hard registers, we need to copy it. */
2067 CALL_INSN_FUNCTION_USAGE (copy)
2068 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn), map);
2072 try_constants (cc0_insn, map);
2075 try_constants (copy, map);
2077 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2078 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
2079 map->const_equiv_map[i] = 0;
2083 /* If this is the loop start label, then we don't need to emit a
2084 copy of this label since no one will use it. */
2086 if (insn != start_label)
2088 copy = emit_label (get_label_from_map (map,
2089 CODE_LABEL_NUMBER (insn)));
2095 copy = emit_barrier ();
2099 /* VTOP notes are valid only before the loop exit test. If placed
2100 anywhere else, loop may generate bad code. */
2102 if (NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED
2103 && (NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_VTOP
2104 || (last_iteration && unroll_type != UNROLL_COMPLETELY)))
2105 copy = emit_note (NOTE_SOURCE_FILE (insn),
2106 NOTE_LINE_NUMBER (insn));
2116 map->insn_map[INSN_UID (insn)] = copy;
2118 while (insn != copy_end);
2120 /* Now finish coping the REG_NOTES. */
2124 insn = NEXT_INSN (insn);
2125 if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
2126 || GET_CODE (insn) == CALL_INSN)
2127 && map->insn_map[INSN_UID (insn)])
2128 final_reg_note_copy (REG_NOTES (map->insn_map[INSN_UID (insn)]), map);
2130 while (insn != copy_end);
2132 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2133 each of these notes here, since there may be some important ones, such as
2134 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2135 iteration, because the original notes won't be deleted.
2137 We can't use insert_before here, because when from preconditioning,
2138 insert_before points before the loop. We can't use copy_end, because
2139 there may be insns already inserted after it (which we don't want to
2140 copy) when not from preconditioning code. */
2142 if (! last_iteration)
2144 for (insn = copy_notes_from; insn != loop_end; insn = NEXT_INSN (insn))
2146 if (GET_CODE (insn) == NOTE
2147 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_DELETED)
2148 emit_note (NOTE_SOURCE_FILE (insn), NOTE_LINE_NUMBER (insn));
2152 if (final_label && LABEL_NUSES (final_label) > 0)
2153 emit_label (final_label);
2155 tem = gen_sequence ();
2157 emit_insn_before (tem, insert_before);
2160 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2161 emitted. This will correctly handle the case where the increment value
2162 won't fit in the immediate field of a PLUS insns. */
2165 emit_unrolled_add (dest_reg, src_reg, increment)
2166 rtx dest_reg, src_reg, increment;
2170 result = expand_binop (GET_MODE (dest_reg), add_optab, src_reg, increment,
2171 dest_reg, 0, OPTAB_LIB_WIDEN);
2173 if (dest_reg != result)
2174 emit_move_insn (dest_reg, result);
2177 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2178 is a backward branch in that range that branches to somewhere between
2179 LOOP_START and INSN. Returns 0 otherwise. */
2181 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2182 In practice, this is not a problem, because this function is seldom called,
2183 and uses a negligible amount of CPU time on average. */
2186 back_branch_in_range_p (insn, loop_start, loop_end)
2188 rtx loop_start, loop_end;
2190 rtx p, q, target_insn;
2191 rtx orig_loop_end = loop_end;
2193 /* Stop before we get to the backward branch at the end of the loop. */
2194 loop_end = prev_nonnote_insn (loop_end);
2195 if (GET_CODE (loop_end) == BARRIER)
2196 loop_end = PREV_INSN (loop_end);
2198 /* Check in case insn has been deleted, search forward for first non
2199 deleted insn following it. */
2200 while (INSN_DELETED_P (insn))
2201 insn = NEXT_INSN (insn);
2203 /* Check for the case where insn is the last insn in the loop. Deal
2204 with the case where INSN was a deleted loop test insn, in which case
2205 it will now be the NOTE_LOOP_END. */
2206 if (insn == loop_end || insn == orig_loop_end)
2209 for (p = NEXT_INSN (insn); p != loop_end; p = NEXT_INSN (p))
2211 if (GET_CODE (p) == JUMP_INSN)
2213 target_insn = JUMP_LABEL (p);
2215 /* Search from loop_start to insn, to see if one of them is
2216 the target_insn. We can't use INSN_LUID comparisons here,
2217 since insn may not have an LUID entry. */
2218 for (q = loop_start; q != insn; q = NEXT_INSN (q))
2219 if (q == target_insn)
2227 /* Try to generate the simplest rtx for the expression
2228 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2232 fold_rtx_mult_add (mult1, mult2, add1, mode)
2233 rtx mult1, mult2, add1;
2234 enum machine_mode mode;
2239 /* The modes must all be the same. This should always be true. For now,
2240 check to make sure. */
2241 if ((GET_MODE (mult1) != mode && GET_MODE (mult1) != VOIDmode)
2242 || (GET_MODE (mult2) != mode && GET_MODE (mult2) != VOIDmode)
2243 || (GET_MODE (add1) != mode && GET_MODE (add1) != VOIDmode))
2246 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2247 will be a constant. */
2248 if (GET_CODE (mult1) == CONST_INT)
2255 mult_res = simplify_binary_operation (MULT, mode, mult1, mult2);
2257 mult_res = gen_rtx_MULT (mode, mult1, mult2);
2259 /* Again, put the constant second. */
2260 if (GET_CODE (add1) == CONST_INT)
2267 result = simplify_binary_operation (PLUS, mode, add1, mult_res);
2269 result = gen_rtx_PLUS (mode, add1, mult_res);
2274 /* Searches the list of induction struct's for the biv BL, to try to calculate
2275 the total increment value for one iteration of the loop as a constant.
2277 Returns the increment value as an rtx, simplified as much as possible,
2278 if it can be calculated. Otherwise, returns 0. */
2281 biv_total_increment (bl, loop_start, loop_end)
2282 struct iv_class *bl;
2283 rtx loop_start, loop_end;
2285 struct induction *v;
2288 /* For increment, must check every instruction that sets it. Each
2289 instruction must be executed only once each time through the loop.
2290 To verify this, we check that the insn is always executed, and that
2291 there are no backward branches after the insn that branch to before it.
2292 Also, the insn must have a mult_val of one (to make sure it really is
2295 result = const0_rtx;
2296 for (v = bl->biv; v; v = v->next_iv)
2298 if (v->always_computable && v->mult_val == const1_rtx
2299 && ! back_branch_in_range_p (v->insn, loop_start, loop_end))
2300 result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
2308 /* Determine the initial value of the iteration variable, and the amount
2309 that it is incremented each loop. Use the tables constructed by
2310 the strength reduction pass to calculate these values.
2312 Initial_value and/or increment are set to zero if their values could not
2316 iteration_info (iteration_var, initial_value, increment, loop_start, loop_end)
2317 rtx iteration_var, *initial_value, *increment;
2318 rtx loop_start, loop_end;
2320 struct iv_class *bl;
2322 struct induction *v;
2325 /* Clear the result values, in case no answer can be found. */
2329 /* The iteration variable can be either a giv or a biv. Check to see
2330 which it is, and compute the variable's initial value, and increment
2331 value if possible. */
2333 /* If this is a new register, can't handle it since we don't have any
2334 reg_iv_type entry for it. */
2335 if (REGNO (iteration_var) >= max_reg_before_loop)
2337 if (loop_dump_stream)
2338 fprintf (loop_dump_stream,
2339 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2343 /* Reject iteration variables larger than the host wide int size, since they
2344 could result in a number of iterations greater than the range of our
2345 `unsigned HOST_WIDE_INT' variable loop_n_iterations. */
2346 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var))
2347 > HOST_BITS_PER_WIDE_INT))
2349 if (loop_dump_stream)
2350 fprintf (loop_dump_stream,
2351 "Loop unrolling: Iteration var rejected because mode too large.\n");
2354 else if (GET_MODE_CLASS (GET_MODE (iteration_var)) != MODE_INT)
2356 if (loop_dump_stream)
2357 fprintf (loop_dump_stream,
2358 "Loop unrolling: Iteration var not an integer.\n");
2361 else if (reg_iv_type[REGNO (iteration_var)] == BASIC_INDUCT)
2363 /* Grab initial value, only useful if it is a constant. */
2364 bl = reg_biv_class[REGNO (iteration_var)];
2365 *initial_value = bl->initial_value;
2367 *increment = biv_total_increment (bl, loop_start, loop_end);
2369 else if (reg_iv_type[REGNO (iteration_var)] == GENERAL_INDUCT)
2372 /* ??? The code below does not work because the incorrect number of
2373 iterations is calculated when the biv is incremented after the giv
2374 is set (which is the usual case). This can probably be accounted
2375 for by biasing the initial_value by subtracting the amount of the
2376 increment that occurs between the giv set and the giv test. However,
2377 a giv as an iterator is very rare, so it does not seem worthwhile
2379 /* ??? An example failure is: i = 6; do {;} while (i++ < 9). */
2380 if (loop_dump_stream)
2381 fprintf (loop_dump_stream,
2382 "Loop unrolling: Giv iterators are not handled.\n");
2385 /* Initial value is mult_val times the biv's initial value plus
2386 add_val. Only useful if it is a constant. */
2387 v = reg_iv_info[REGNO (iteration_var)];
2388 bl = reg_biv_class[REGNO (v->src_reg)];
2389 *initial_value = fold_rtx_mult_add (v->mult_val, bl->initial_value,
2390 v->add_val, v->mode);
2392 /* Increment value is mult_val times the increment value of the biv. */
2394 *increment = biv_total_increment (bl, loop_start, loop_end);
2396 *increment = fold_rtx_mult_add (v->mult_val, *increment, const0_rtx,
2402 if (loop_dump_stream)
2403 fprintf (loop_dump_stream,
2404 "Loop unrolling: Not basic or general induction var.\n");
2409 /* Calculate the approximate final value of the iteration variable
2410 which has an loop exit test with code COMPARISON_CODE and comparison value
2411 of COMPARISON_VALUE. Also returns an indication of whether the comparison
2412 was signed or unsigned, and the direction of the comparison. This info is
2413 needed to calculate the number of loop iterations. */
2416 approx_final_value (comparison_code, comparison_value, unsigned_p, compare_dir)
2417 enum rtx_code comparison_code;
2418 rtx comparison_value;
2422 /* Calculate the final value of the induction variable.
2423 The exact final value depends on the branch operator, and increment sign.
2424 This is only an approximate value. It will be wrong if the iteration
2425 variable is not incremented by one each time through the loop, and
2426 approx final value - start value % increment != 0. */
2429 switch (comparison_code)
2435 return plus_constant (comparison_value, 1);
2440 return plus_constant (comparison_value, -1);
2442 /* Can not calculate a final value for this case. */
2449 return comparison_value;
2455 return comparison_value;
2458 return comparison_value;
2464 /* For each biv and giv, determine whether it can be safely split into
2465 a different variable for each unrolled copy of the loop body. If it
2466 is safe to split, then indicate that by saving some useful info
2467 in the splittable_regs array.
2469 If the loop is being completely unrolled, then splittable_regs will hold
2470 the current value of the induction variable while the loop is unrolled.
2471 It must be set to the initial value of the induction variable here.
2472 Otherwise, splittable_regs will hold the difference between the current
2473 value of the induction variable and the value the induction variable had
2474 at the top of the loop. It must be set to the value 0 here.
2476 Returns the total number of instructions that set registers that are
2479 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2480 constant values are unnecessary, since we can easily calculate increment
2481 values in this case even if nothing is constant. The increment value
2482 should not involve a multiply however. */
2484 /* ?? Even if the biv/giv increment values aren't constant, it may still
2485 be beneficial to split the variable if the loop is only unrolled a few
2486 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2489 find_splittable_regs (unroll_type, loop_start, loop_end, end_insert_before,
2491 enum unroll_types unroll_type;
2492 rtx loop_start, loop_end;
2493 rtx end_insert_before;
2496 struct iv_class *bl;
2497 struct induction *v;
2499 rtx biv_final_value;
2503 for (bl = loop_iv_list; bl; bl = bl->next)
2505 /* Biv_total_increment must return a constant value,
2506 otherwise we can not calculate the split values. */
2508 increment = biv_total_increment (bl, loop_start, loop_end);
2509 if (! increment || GET_CODE (increment) != CONST_INT)
2512 /* The loop must be unrolled completely, or else have a known number
2513 of iterations and only one exit, or else the biv must be dead
2514 outside the loop, or else the final value must be known. Otherwise,
2515 it is unsafe to split the biv since it may not have the proper
2516 value on loop exit. */
2518 /* loop_number_exit_count is non-zero if the loop has an exit other than
2519 a fall through at the end. */
2522 biv_final_value = 0;
2523 if (unroll_type != UNROLL_COMPLETELY
2524 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2525 || unroll_type == UNROLL_NAIVE)
2526 && (uid_luid[REGNO_LAST_UID (bl->regno)] >= INSN_LUID (loop_end)
2528 || INSN_UID (bl->init_insn) >= max_uid_for_loop
2529 || (uid_luid[REGNO_FIRST_UID (bl->regno)]
2530 < INSN_LUID (bl->init_insn))
2531 || reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
2532 && ! (biv_final_value = final_biv_value (bl, loop_start, loop_end)))
2535 /* If any of the insns setting the BIV don't do so with a simple
2536 PLUS, we don't know how to split it. */
2537 for (v = bl->biv; biv_splittable && v; v = v->next_iv)
2538 if ((tem = single_set (v->insn)) == 0
2539 || GET_CODE (SET_DEST (tem)) != REG
2540 || REGNO (SET_DEST (tem)) != bl->regno
2541 || GET_CODE (SET_SRC (tem)) != PLUS)
2544 /* If final value is non-zero, then must emit an instruction which sets
2545 the value of the biv to the proper value. This is done after
2546 handling all of the givs, since some of them may need to use the
2547 biv's value in their initialization code. */
2549 /* This biv is splittable. If completely unrolling the loop, save
2550 the biv's initial value. Otherwise, save the constant zero. */
2552 if (biv_splittable == 1)
2554 if (unroll_type == UNROLL_COMPLETELY)
2556 /* If the initial value of the biv is itself (i.e. it is too
2557 complicated for strength_reduce to compute), or is a hard
2558 register, or it isn't invariant, then we must create a new
2559 pseudo reg to hold the initial value of the biv. */
2561 if (GET_CODE (bl->initial_value) == REG
2562 && (REGNO (bl->initial_value) == bl->regno
2563 || REGNO (bl->initial_value) < FIRST_PSEUDO_REGISTER
2564 || ! invariant_p (bl->initial_value)))
2566 rtx tem = gen_reg_rtx (bl->biv->mode);
2568 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2569 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2572 if (loop_dump_stream)
2573 fprintf (loop_dump_stream, "Biv %d initial value remapped to %d.\n",
2574 bl->regno, REGNO (tem));
2576 splittable_regs[bl->regno] = tem;
2579 splittable_regs[bl->regno] = bl->initial_value;
2582 splittable_regs[bl->regno] = const0_rtx;
2584 /* Save the number of instructions that modify the biv, so that
2585 we can treat the last one specially. */
2587 splittable_regs_updates[bl->regno] = bl->biv_count;
2588 result += bl->biv_count;
2590 if (loop_dump_stream)
2591 fprintf (loop_dump_stream,
2592 "Biv %d safe to split.\n", bl->regno);
2595 /* Check every giv that depends on this biv to see whether it is
2596 splittable also. Even if the biv isn't splittable, givs which
2597 depend on it may be splittable if the biv is live outside the
2598 loop, and the givs aren't. */
2600 result += find_splittable_givs (bl, unroll_type, loop_start, loop_end,
2601 increment, unroll_number);
2603 /* If final value is non-zero, then must emit an instruction which sets
2604 the value of the biv to the proper value. This is done after
2605 handling all of the givs, since some of them may need to use the
2606 biv's value in their initialization code. */
2607 if (biv_final_value)
2609 /* If the loop has multiple exits, emit the insns before the
2610 loop to ensure that it will always be executed no matter
2611 how the loop exits. Otherwise emit the insn after the loop,
2612 since this is slightly more efficient. */
2613 if (! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
2614 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2619 /* Create a new register to hold the value of the biv, and then
2620 set the biv to its final value before the loop start. The biv
2621 is set to its final value before loop start to ensure that
2622 this insn will always be executed, no matter how the loop
2624 rtx tem = gen_reg_rtx (bl->biv->mode);
2625 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2627 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2629 emit_insn_before (gen_move_insn (bl->biv->src_reg,
2633 if (loop_dump_stream)
2634 fprintf (loop_dump_stream, "Biv %d mapped to %d for split.\n",
2635 REGNO (bl->biv->src_reg), REGNO (tem));
2637 /* Set up the mapping from the original biv register to the new
2639 bl->biv->src_reg = tem;
2646 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2647 for the instruction that is using it. Do not make any changes to that
2651 verify_addresses (v, giv_inc, unroll_number)
2652 struct induction *v;
2657 rtx orig_addr = *v->location;
2658 rtx last_addr = plus_constant (v->dest_reg,
2659 INTVAL (giv_inc) * (unroll_number - 1));
2661 /* First check to see if either address would fail. Handle the fact
2662 that we have may have a match_dup. */
2663 if (! validate_replace_rtx (*v->location, v->dest_reg, v->insn)
2664 || ! validate_replace_rtx (*v->location, last_addr, v->insn))
2667 /* Now put things back the way they were before. This should always
2669 if (! validate_replace_rtx (*v->location, orig_addr, v->insn))
2675 /* For every giv based on the biv BL, check to determine whether it is
2676 splittable. This is a subroutine to find_splittable_regs ().
2678 Return the number of instructions that set splittable registers. */
2681 find_splittable_givs (bl, unroll_type, loop_start, loop_end, increment,
2683 struct iv_class *bl;
2684 enum unroll_types unroll_type;
2685 rtx loop_start, loop_end;
2689 struct induction *v, *v2;
2694 /* Scan the list of givs, and set the same_insn field when there are
2695 multiple identical givs in the same insn. */
2696 for (v = bl->giv; v; v = v->next_iv)
2697 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2698 if (v->insn == v2->insn && rtx_equal_p (v->new_reg, v2->new_reg)
2702 for (v = bl->giv; v; v = v->next_iv)
2706 /* Only split the giv if it has already been reduced, or if the loop is
2707 being completely unrolled. */
2708 if (unroll_type != UNROLL_COMPLETELY && v->ignore)
2711 /* The giv can be split if the insn that sets the giv is executed once
2712 and only once on every iteration of the loop. */
2713 /* An address giv can always be split. v->insn is just a use not a set,
2714 and hence it does not matter whether it is always executed. All that
2715 matters is that all the biv increments are always executed, and we
2716 won't reach here if they aren't. */
2717 if (v->giv_type != DEST_ADDR
2718 && (! v->always_computable
2719 || back_branch_in_range_p (v->insn, loop_start, loop_end)))
2722 /* The giv increment value must be a constant. */
2723 giv_inc = fold_rtx_mult_add (v->mult_val, increment, const0_rtx,
2725 if (! giv_inc || GET_CODE (giv_inc) != CONST_INT)
2728 /* The loop must be unrolled completely, or else have a known number of
2729 iterations and only one exit, or else the giv must be dead outside
2730 the loop, or else the final value of the giv must be known.
2731 Otherwise, it is not safe to split the giv since it may not have the
2732 proper value on loop exit. */
2734 /* The used outside loop test will fail for DEST_ADDR givs. They are
2735 never used outside the loop anyways, so it is always safe to split a
2739 if (unroll_type != UNROLL_COMPLETELY
2740 && (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
2741 || unroll_type == UNROLL_NAIVE)
2742 && v->giv_type != DEST_ADDR
2743 /* The next part is true if the pseudo is used outside the loop.
2744 We assume that this is true for any pseudo created after loop
2745 starts, because we don't have a reg_n_info entry for them. */
2746 && (REGNO (v->dest_reg) >= max_reg_before_loop
2747 || (REGNO_FIRST_UID (REGNO (v->dest_reg)) != INSN_UID (v->insn)
2748 /* Check for the case where the pseudo is set by a shift/add
2749 sequence, in which case the first insn setting the pseudo
2750 is the first insn of the shift/add sequence. */
2751 && (! (tem = find_reg_note (v->insn, REG_RETVAL, NULL_RTX))
2752 || (REGNO_FIRST_UID (REGNO (v->dest_reg))
2753 != INSN_UID (XEXP (tem, 0)))))
2754 /* Line above always fails if INSN was moved by loop opt. */
2755 || (uid_luid[REGNO_LAST_UID (REGNO (v->dest_reg))]
2756 >= INSN_LUID (loop_end)))
2757 && ! (final_value = v->final_value))
2761 /* Currently, non-reduced/final-value givs are never split. */
2762 /* Should emit insns after the loop if possible, as the biv final value
2765 /* If the final value is non-zero, and the giv has not been reduced,
2766 then must emit an instruction to set the final value. */
2767 if (final_value && !v->new_reg)
2769 /* Create a new register to hold the value of the giv, and then set
2770 the giv to its final value before the loop start. The giv is set
2771 to its final value before loop start to ensure that this insn
2772 will always be executed, no matter how we exit. */
2773 tem = gen_reg_rtx (v->mode);
2774 emit_insn_before (gen_move_insn (tem, v->dest_reg), loop_start);
2775 emit_insn_before (gen_move_insn (v->dest_reg, final_value),
2778 if (loop_dump_stream)
2779 fprintf (loop_dump_stream, "Giv %d mapped to %d for split.\n",
2780 REGNO (v->dest_reg), REGNO (tem));
2786 /* This giv is splittable. If completely unrolling the loop, save the
2787 giv's initial value. Otherwise, save the constant zero for it. */
2789 if (unroll_type == UNROLL_COMPLETELY)
2791 /* It is not safe to use bl->initial_value here, because it may not
2792 be invariant. It is safe to use the initial value stored in
2793 the splittable_regs array if it is set. In rare cases, it won't
2794 be set, so then we do exactly the same thing as
2795 find_splittable_regs does to get a safe value. */
2796 rtx biv_initial_value;
2798 if (splittable_regs[bl->regno])
2799 biv_initial_value = splittable_regs[bl->regno];
2800 else if (GET_CODE (bl->initial_value) != REG
2801 || (REGNO (bl->initial_value) != bl->regno
2802 && REGNO (bl->initial_value) >= FIRST_PSEUDO_REGISTER))
2803 biv_initial_value = bl->initial_value;
2806 rtx tem = gen_reg_rtx (bl->biv->mode);
2808 record_base_value (REGNO (tem), bl->biv->add_val, 0);
2809 emit_insn_before (gen_move_insn (tem, bl->biv->src_reg),
2811 biv_initial_value = tem;
2813 value = fold_rtx_mult_add (v->mult_val, biv_initial_value,
2814 v->add_val, v->mode);
2821 /* If a giv was combined with another giv, then we can only split
2822 this giv if the giv it was combined with was reduced. This
2823 is because the value of v->new_reg is meaningless in this
2825 if (v->same && ! v->same->new_reg)
2827 if (loop_dump_stream)
2828 fprintf (loop_dump_stream,
2829 "giv combined with unreduced giv not split.\n");
2832 /* If the giv is an address destination, it could be something other
2833 than a simple register, these have to be treated differently. */
2834 else if (v->giv_type == DEST_REG)
2836 /* If value is not a constant, register, or register plus
2837 constant, then compute its value into a register before
2838 loop start. This prevents invalid rtx sharing, and should
2839 generate better code. We can use bl->initial_value here
2840 instead of splittable_regs[bl->regno] because this code
2841 is going before the loop start. */
2842 if (unroll_type == UNROLL_COMPLETELY
2843 && GET_CODE (value) != CONST_INT
2844 && GET_CODE (value) != REG
2845 && (GET_CODE (value) != PLUS
2846 || GET_CODE (XEXP (value, 0)) != REG
2847 || GET_CODE (XEXP (value, 1)) != CONST_INT))
2849 rtx tem = gen_reg_rtx (v->mode);
2850 record_base_value (REGNO (tem), v->add_val, 0);
2851 emit_iv_add_mult (bl->initial_value, v->mult_val,
2852 v->add_val, tem, loop_start);
2856 splittable_regs[REGNO (v->new_reg)] = value;
2860 /* Splitting address givs is useful since it will often allow us
2861 to eliminate some increment insns for the base giv as
2864 /* If the addr giv is combined with a dest_reg giv, then all
2865 references to that dest reg will be remapped, which is NOT
2866 what we want for split addr regs. We always create a new
2867 register for the split addr giv, just to be safe. */
2869 /* If we have multiple identical address givs within a
2870 single instruction, then use a single pseudo reg for
2871 both. This is necessary in case one is a match_dup
2874 v->const_adjust = 0;
2878 v->dest_reg = v->same_insn->dest_reg;
2879 if (loop_dump_stream)
2880 fprintf (loop_dump_stream,
2881 "Sharing address givs in insn %d\n",
2882 INSN_UID (v->insn));
2884 /* If multiple address GIVs have been combined with the
2885 same dest_reg GIV, do not create a new register for
2887 else if (unroll_type != UNROLL_COMPLETELY
2888 && v->giv_type == DEST_ADDR
2889 && v->same && v->same->giv_type == DEST_ADDR
2890 && v->same->unrolled
2891 /* combine_givs_p may return true for some cases
2892 where the add and mult values are not equal.
2893 To share a register here, the values must be
2895 && rtx_equal_p (v->same->mult_val, v->mult_val)
2896 && rtx_equal_p (v->same->add_val, v->add_val))
2899 v->dest_reg = v->same->dest_reg;
2902 else if (unroll_type != UNROLL_COMPLETELY)
2904 /* If not completely unrolling the loop, then create a new
2905 register to hold the split value of the DEST_ADDR giv.
2906 Emit insn to initialize its value before loop start. */
2908 rtx tem = gen_reg_rtx (v->mode);
2909 record_base_value (REGNO (tem), v->add_val, 0);
2911 /* If the address giv has a constant in its new_reg value,
2912 then this constant can be pulled out and put in value,
2913 instead of being part of the initialization code. */
2915 if (GET_CODE (v->new_reg) == PLUS
2916 && GET_CODE (XEXP (v->new_reg, 1)) == CONST_INT)
2919 = plus_constant (tem, INTVAL (XEXP (v->new_reg,1)));
2921 /* Only succeed if this will give valid addresses.
2922 Try to validate both the first and the last
2923 address resulting from loop unrolling, if
2924 one fails, then can't do const elim here. */
2925 if (verify_addresses (v, giv_inc, unroll_number))
2927 /* Save the negative of the eliminated const, so
2928 that we can calculate the dest_reg's increment
2930 v->const_adjust = - INTVAL (XEXP (v->new_reg, 1));
2932 v->new_reg = XEXP (v->new_reg, 0);
2933 if (loop_dump_stream)
2934 fprintf (loop_dump_stream,
2935 "Eliminating constant from giv %d\n",
2944 /* If the address hasn't been checked for validity yet, do so
2945 now, and fail completely if either the first or the last
2946 unrolled copy of the address is not a valid address
2947 for the instruction that uses it. */
2948 if (v->dest_reg == tem
2949 && ! verify_addresses (v, giv_inc, unroll_number))
2951 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
2952 if (v2->same_insn == v)
2955 if (loop_dump_stream)
2956 fprintf (loop_dump_stream,
2957 "Invalid address for giv at insn %d\n",
2958 INSN_UID (v->insn));
2962 /* We set this after the address check, to guarantee that
2963 the register will be initialized. */
2966 /* To initialize the new register, just move the value of
2967 new_reg into it. This is not guaranteed to give a valid
2968 instruction on machines with complex addressing modes.
2969 If we can't recognize it, then delete it and emit insns
2970 to calculate the value from scratch. */
2971 emit_insn_before (gen_rtx_SET (VOIDmode, tem,
2972 copy_rtx (v->new_reg)),
2974 if (recog_memoized (PREV_INSN (loop_start)) < 0)
2978 /* We can't use bl->initial_value to compute the initial
2979 value, because the loop may have been preconditioned.
2980 We must calculate it from NEW_REG. Try using
2981 force_operand instead of emit_iv_add_mult. */
2982 delete_insn (PREV_INSN (loop_start));
2985 ret = force_operand (v->new_reg, tem);
2987 emit_move_insn (tem, ret);
2988 sequence = gen_sequence ();
2990 emit_insn_before (sequence, loop_start);
2992 if (loop_dump_stream)
2993 fprintf (loop_dump_stream,
2994 "Invalid init insn, rewritten.\n");
2999 v->dest_reg = value;
3001 /* Check the resulting address for validity, and fail
3002 if the resulting address would be invalid. */
3003 if (! verify_addresses (v, giv_inc, unroll_number))
3005 for (v2 = v->next_iv; v2; v2 = v2->next_iv)
3006 if (v2->same_insn == v)
3009 if (loop_dump_stream)
3010 fprintf (loop_dump_stream,
3011 "Invalid address for giv at insn %d\n",
3012 INSN_UID (v->insn));
3017 /* Store the value of dest_reg into the insn. This sharing
3018 will not be a problem as this insn will always be copied
3021 *v->location = v->dest_reg;
3023 /* If this address giv is combined with a dest reg giv, then
3024 save the base giv's induction pointer so that we will be
3025 able to handle this address giv properly. The base giv
3026 itself does not have to be splittable. */
3028 if (v->same && v->same->giv_type == DEST_REG)
3029 addr_combined_regs[REGNO (v->same->new_reg)] = v->same;
3031 if (GET_CODE (v->new_reg) == REG)
3033 /* This giv maybe hasn't been combined with any others.
3034 Make sure that it's giv is marked as splittable here. */
3036 splittable_regs[REGNO (v->new_reg)] = value;
3038 /* Make it appear to depend upon itself, so that the
3039 giv will be properly split in the main loop above. */
3043 addr_combined_regs[REGNO (v->new_reg)] = v;
3047 if (loop_dump_stream)
3048 fprintf (loop_dump_stream, "DEST_ADDR giv being split.\n");
3054 /* Currently, unreduced giv's can't be split. This is not too much
3055 of a problem since unreduced giv's are not live across loop
3056 iterations anyways. When unrolling a loop completely though,
3057 it makes sense to reduce&split givs when possible, as this will
3058 result in simpler instructions, and will not require that a reg
3059 be live across loop iterations. */
3061 splittable_regs[REGNO (v->dest_reg)] = value;
3062 fprintf (stderr, "Giv %d at insn %d not reduced\n",
3063 REGNO (v->dest_reg), INSN_UID (v->insn));
3069 /* Unreduced givs are only updated once by definition. Reduced givs
3070 are updated as many times as their biv is. Mark it so if this is
3071 a splittable register. Don't need to do anything for address givs
3072 where this may not be a register. */
3074 if (GET_CODE (v->new_reg) == REG)
3078 count = reg_biv_class[REGNO (v->src_reg)]->biv_count;
3080 splittable_regs_updates[REGNO (v->new_reg)] = count;
3085 if (loop_dump_stream)
3089 if (GET_CODE (v->dest_reg) == CONST_INT)
3091 else if (GET_CODE (v->dest_reg) != REG)
3092 regnum = REGNO (XEXP (v->dest_reg, 0));
3094 regnum = REGNO (v->dest_reg);
3095 fprintf (loop_dump_stream, "Giv %d at insn %d safe to split.\n",
3096 regnum, INSN_UID (v->insn));
3103 /* Try to prove that the register is dead after the loop exits. Trace every
3104 loop exit looking for an insn that will always be executed, which sets
3105 the register to some value, and appears before the first use of the register
3106 is found. If successful, then return 1, otherwise return 0. */
3108 /* ?? Could be made more intelligent in the handling of jumps, so that
3109 it can search past if statements and other similar structures. */
3112 reg_dead_after_loop (reg, loop_start, loop_end)
3113 rtx reg, loop_start, loop_end;
3118 int label_count = 0;
3119 int this_loop_num = uid_loop_num[INSN_UID (loop_start)];
3121 /* In addition to checking all exits of this loop, we must also check
3122 all exits of inner nested loops that would exit this loop. We don't
3123 have any way to identify those, so we just give up if there are any
3124 such inner loop exits. */
3126 for (label = loop_number_exit_labels[this_loop_num]; label;
3127 label = LABEL_NEXTREF (label))
3130 if (label_count != loop_number_exit_count[this_loop_num])
3133 /* HACK: Must also search the loop fall through exit, create a label_ref
3134 here which points to the loop_end, and append the loop_number_exit_labels
3136 label = gen_rtx_LABEL_REF (VOIDmode, loop_end);
3137 LABEL_NEXTREF (label) = loop_number_exit_labels[this_loop_num];
3139 for ( ; label; label = LABEL_NEXTREF (label))
3141 /* Succeed if find an insn which sets the biv or if reach end of
3142 function. Fail if find an insn that uses the biv, or if come to
3143 a conditional jump. */
3145 insn = NEXT_INSN (XEXP (label, 0));
3148 code = GET_CODE (insn);
3149 if (GET_RTX_CLASS (code) == 'i')
3153 if (reg_referenced_p (reg, PATTERN (insn)))
3156 set = single_set (insn);
3157 if (set && rtx_equal_p (SET_DEST (set), reg))
3161 if (code == JUMP_INSN)
3163 if (GET_CODE (PATTERN (insn)) == RETURN)
3165 else if (! simplejump_p (insn)
3166 /* Prevent infinite loop following infinite loops. */
3167 || jump_count++ > 20)
3170 insn = JUMP_LABEL (insn);
3173 insn = NEXT_INSN (insn);
3177 /* Success, the register is dead on all loop exits. */
3181 /* Try to calculate the final value of the biv, the value it will have at
3182 the end of the loop. If we can do it, return that value. */
3185 final_biv_value (bl, loop_start, loop_end)
3186 struct iv_class *bl;
3187 rtx loop_start, loop_end;
3191 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3193 if (GET_MODE_CLASS (bl->biv->mode) != MODE_INT)
3196 /* The final value for reversed bivs must be calculated differently than
3197 for ordinary bivs. In this case, there is already an insn after the
3198 loop which sets this biv's final value (if necessary), and there are
3199 no other loop exits, so we can return any value. */
3202 if (loop_dump_stream)
3203 fprintf (loop_dump_stream,
3204 "Final biv value for %d, reversed biv.\n", bl->regno);
3209 /* Try to calculate the final value as initial value + (number of iterations
3210 * increment). For this to work, increment must be invariant, the only
3211 exit from the loop must be the fall through at the bottom (otherwise
3212 it may not have its final value when the loop exits), and the initial
3213 value of the biv must be invariant. */
3215 if (loop_n_iterations != 0
3216 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]]
3217 && invariant_p (bl->initial_value))
3219 increment = biv_total_increment (bl, loop_start, loop_end);
3221 if (increment && invariant_p (increment))
3223 /* Can calculate the loop exit value, emit insns after loop
3224 end to calculate this value into a temporary register in
3225 case it is needed later. */
3227 tem = gen_reg_rtx (bl->biv->mode);
3228 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3229 /* Make sure loop_end is not the last insn. */
3230 if (NEXT_INSN (loop_end) == 0)
3231 emit_note_after (NOTE_INSN_DELETED, loop_end);
3232 emit_iv_add_mult (increment, GEN_INT (loop_n_iterations),
3233 bl->initial_value, tem, NEXT_INSN (loop_end));
3235 if (loop_dump_stream)
3236 fprintf (loop_dump_stream,
3237 "Final biv value for %d, calculated.\n", bl->regno);
3243 /* Check to see if the biv is dead at all loop exits. */
3244 if (reg_dead_after_loop (bl->biv->src_reg, loop_start, loop_end))
3246 if (loop_dump_stream)
3247 fprintf (loop_dump_stream,
3248 "Final biv value for %d, biv dead after loop exit.\n",
3257 /* Try to calculate the final value of the giv, the value it will have at
3258 the end of the loop. If we can do it, return that value. */
3261 final_giv_value (v, loop_start, loop_end)
3262 struct induction *v;
3263 rtx loop_start, loop_end;
3265 struct iv_class *bl;
3268 rtx insert_before, seq;
3270 bl = reg_biv_class[REGNO (v->src_reg)];
3272 /* The final value for givs which depend on reversed bivs must be calculated
3273 differently than for ordinary givs. In this case, there is already an
3274 insn after the loop which sets this giv's final value (if necessary),
3275 and there are no other loop exits, so we can return any value. */
3278 if (loop_dump_stream)
3279 fprintf (loop_dump_stream,
3280 "Final giv value for %d, depends on reversed biv\n",
3281 REGNO (v->dest_reg));
3285 /* Try to calculate the final value as a function of the biv it depends
3286 upon. The only exit from the loop must be the fall through at the bottom
3287 (otherwise it may not have its final value when the loop exits). */
3289 /* ??? Can calculate the final giv value by subtracting off the
3290 extra biv increments times the giv's mult_val. The loop must have
3291 only one exit for this to work, but the loop iterations does not need
3294 if (loop_n_iterations != 0
3295 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
3297 /* ?? It is tempting to use the biv's value here since these insns will
3298 be put after the loop, and hence the biv will have its final value
3299 then. However, this fails if the biv is subsequently eliminated.
3300 Perhaps determine whether biv's are eliminable before trying to
3301 determine whether giv's are replaceable so that we can use the
3302 biv value here if it is not eliminable. */
3304 /* We are emitting code after the end of the loop, so we must make
3305 sure that bl->initial_value is still valid then. It will still
3306 be valid if it is invariant. */
3308 increment = biv_total_increment (bl, loop_start, loop_end);
3310 if (increment && invariant_p (increment)
3311 && invariant_p (bl->initial_value))
3313 /* Can calculate the loop exit value of its biv as
3314 (loop_n_iterations * increment) + initial_value */
3316 /* The loop exit value of the giv is then
3317 (final_biv_value - extra increments) * mult_val + add_val.
3318 The extra increments are any increments to the biv which
3319 occur in the loop after the giv's value is calculated.
3320 We must search from the insn that sets the giv to the end
3321 of the loop to calculate this value. */
3323 insert_before = NEXT_INSN (loop_end);
3325 /* Put the final biv value in tem. */
3326 tem = gen_reg_rtx (bl->biv->mode);
3327 record_base_value (REGNO (tem), bl->biv->add_val, 0);
3328 emit_iv_add_mult (increment, GEN_INT (loop_n_iterations),
3329 bl->initial_value, tem, insert_before);
3331 /* Subtract off extra increments as we find them. */
3332 for (insn = NEXT_INSN (v->insn); insn != loop_end;
3333 insn = NEXT_INSN (insn))
3335 struct induction *biv;
3337 for (biv = bl->biv; biv; biv = biv->next_iv)
3338 if (biv->insn == insn)
3341 tem = expand_binop (GET_MODE (tem), sub_optab, tem,
3342 biv->add_val, NULL_RTX, 0,
3344 seq = gen_sequence ();
3346 emit_insn_before (seq, insert_before);
3350 /* Now calculate the giv's final value. */
3351 emit_iv_add_mult (tem, v->mult_val, v->add_val, tem,
3354 if (loop_dump_stream)
3355 fprintf (loop_dump_stream,
3356 "Final giv value for %d, calc from biv's value.\n",
3357 REGNO (v->dest_reg));
3363 /* Replaceable giv's should never reach here. */
3367 /* Check to see if the biv is dead at all loop exits. */
3368 if (reg_dead_after_loop (v->dest_reg, loop_start, loop_end))
3370 if (loop_dump_stream)
3371 fprintf (loop_dump_stream,
3372 "Final giv value for %d, giv dead after loop exit.\n",
3373 REGNO (v->dest_reg));
3382 /* Calculate the number of loop iterations. Returns the exact number of loop
3383 iterations if it can be calculated, otherwise returns zero. */
3385 unsigned HOST_WIDE_INT
3386 loop_iterations (loop_start, loop_end)
3387 rtx loop_start, loop_end;
3389 rtx comparison, comparison_value;
3390 rtx iteration_var, initial_value, increment, final_value;
3391 enum rtx_code comparison_code;
3394 int unsigned_compare, compare_dir, final_larger;
3395 unsigned long tempu;
3398 /* First find the iteration variable. If the last insn is a conditional
3399 branch, and the insn before tests a register value, make that the
3400 iteration variable. */
3402 loop_initial_value = 0;
3404 loop_final_value = 0;
3405 loop_iteration_var = 0;
3407 /* We used to use pren_nonnote_insn here, but that fails because it might
3408 accidentally get the branch for a contained loop if the branch for this
3409 loop was deleted. We can only trust branches immediately before the
3411 last_loop_insn = PREV_INSN (loop_end);
3413 comparison = get_condition_for_loop (last_loop_insn);
3414 if (comparison == 0)
3416 if (loop_dump_stream)
3417 fprintf (loop_dump_stream,
3418 "Loop unrolling: No final conditional branch found.\n");
3422 /* ??? Get_condition may switch position of induction variable and
3423 invariant register when it canonicalizes the comparison. */
3425 comparison_code = GET_CODE (comparison);
3426 iteration_var = XEXP (comparison, 0);
3427 comparison_value = XEXP (comparison, 1);
3429 if (GET_CODE (iteration_var) != REG)
3431 if (loop_dump_stream)
3432 fprintf (loop_dump_stream,
3433 "Loop unrolling: Comparison not against register.\n");
3437 /* Loop iterations is always called before any new registers are created
3438 now, so this should never occur. */
3440 if (REGNO (iteration_var) >= max_reg_before_loop)
3443 iteration_info (iteration_var, &initial_value, &increment,
3444 loop_start, loop_end);
3445 if (initial_value == 0)
3446 /* iteration_info already printed a message. */
3449 /* If the comparison value is an invariant register, then try to find
3450 its value from the insns before the start of the loop. */
3452 if (GET_CODE (comparison_value) == REG && invariant_p (comparison_value))
3456 for (insn = PREV_INSN (loop_start); insn ; insn = PREV_INSN (insn))
3458 if (GET_CODE (insn) == CODE_LABEL)
3461 else if (GET_RTX_CLASS (GET_CODE (insn)) == 'i'
3462 && reg_set_p (comparison_value, insn))
3464 /* We found the last insn before the loop that sets the register.
3465 If it sets the entire register, and has a REG_EQUAL note,
3466 then use the value of the REG_EQUAL note. */
3467 if ((set = single_set (insn))
3468 && (SET_DEST (set) == comparison_value))
3470 rtx note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
3472 /* Only use the REG_EQUAL note if it is a constant.
3473 Other things, divide in particular, will cause
3474 problems later if we use them. */
3475 if (note && GET_CODE (XEXP (note, 0)) != EXPR_LIST
3476 && CONSTANT_P (XEXP (note, 0)))
3477 comparison_value = XEXP (note, 0);
3484 final_value = approx_final_value (comparison_code, comparison_value,
3485 &unsigned_compare, &compare_dir);
3487 /* Save the calculated values describing this loop's bounds, in case
3488 precondition_loop_p will need them later. These values can not be
3489 recalculated inside precondition_loop_p because strength reduction
3490 optimizations may obscure the loop's structure. */
3492 loop_iteration_var = iteration_var;
3493 loop_initial_value = initial_value;
3494 loop_increment = increment;
3495 loop_final_value = final_value;
3496 loop_comparison_code = comparison_code;
3500 if (loop_dump_stream)
3501 fprintf (loop_dump_stream,
3502 "Loop unrolling: Increment value can't be calculated.\n");
3505 else if (GET_CODE (increment) != CONST_INT)
3507 if (loop_dump_stream)
3508 fprintf (loop_dump_stream,
3509 "Loop unrolling: Increment value not constant.\n");
3512 else if (GET_CODE (initial_value) != CONST_INT)
3514 if (loop_dump_stream)
3515 fprintf (loop_dump_stream,
3516 "Loop unrolling: Initial value not constant.\n");
3519 else if (final_value == 0)
3521 if (loop_dump_stream)
3522 fprintf (loop_dump_stream,
3523 "Loop unrolling: EQ comparison loop.\n");
3526 else if (GET_CODE (final_value) != CONST_INT)
3528 if (loop_dump_stream)
3529 fprintf (loop_dump_stream,
3530 "Loop unrolling: Final value not constant.\n");
3534 /* ?? Final value and initial value do not have to be constants.
3535 Only their difference has to be constant. When the iteration variable
3536 is an array address, the final value and initial value might both
3537 be addresses with the same base but different constant offsets.
3538 Final value must be invariant for this to work.
3540 To do this, need some way to find the values of registers which are
3543 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3544 if (unsigned_compare)
3546 = ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3547 > (unsigned HOST_WIDE_INT) INTVAL (initial_value))
3548 - ((unsigned HOST_WIDE_INT) INTVAL (final_value)
3549 < (unsigned HOST_WIDE_INT) INTVAL (initial_value));
3551 final_larger = (INTVAL (final_value) > INTVAL (initial_value))
3552 - (INTVAL (final_value) < INTVAL (initial_value));
3554 if (INTVAL (increment) > 0)
3556 else if (INTVAL (increment) == 0)
3561 /* There are 27 different cases: compare_dir = -1, 0, 1;
3562 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3563 There are 4 normal cases, 4 reverse cases (where the iteration variable
3564 will overflow before the loop exits), 4 infinite loop cases, and 15
3565 immediate exit (0 or 1 iteration depending on loop type) cases.
3566 Only try to optimize the normal cases. */
3568 /* (compare_dir/final_larger/increment_dir)
3569 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3570 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3571 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3572 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3574 /* ?? If the meaning of reverse loops (where the iteration variable
3575 will overflow before the loop exits) is undefined, then could
3576 eliminate all of these special checks, and just always assume
3577 the loops are normal/immediate/infinite. Note that this means
3578 the sign of increment_dir does not have to be known. Also,
3579 since it does not really hurt if immediate exit loops or infinite loops
3580 are optimized, then that case could be ignored also, and hence all
3581 loops can be optimized.
3583 According to ANSI Spec, the reverse loop case result is undefined,
3584 because the action on overflow is undefined.
3586 See also the special test for NE loops below. */
3588 if (final_larger == increment_dir && final_larger != 0
3589 && (final_larger == compare_dir || compare_dir == 0))
3594 if (loop_dump_stream)
3595 fprintf (loop_dump_stream,
3596 "Loop unrolling: Not normal loop.\n");
3600 /* Calculate the number of iterations, final_value is only an approximation,
3601 so correct for that. Note that tempu and loop_n_iterations are
3602 unsigned, because they can be as large as 2^n - 1. */
3604 i = INTVAL (increment);
3606 tempu = INTVAL (final_value) - INTVAL (initial_value);
3609 tempu = INTVAL (initial_value) - INTVAL (final_value);
3615 /* For NE tests, make sure that the iteration variable won't miss the
3616 final value. If tempu mod i is not zero, then the iteration variable
3617 will overflow before the loop exits, and we can not calculate the
3618 number of iterations. */
3619 if (compare_dir == 0 && (tempu % i) != 0)
3622 return tempu / i + ((tempu % i) != 0);
3625 /* Replace uses of split bivs with their split pseudo register. This is
3626 for original instructions which remain after loop unrolling without
3630 remap_split_bivs (x)
3633 register enum rtx_code code;
3640 code = GET_CODE (x);
3655 /* If non-reduced/final-value givs were split, then this would also
3656 have to remap those givs also. */
3658 if (REGNO (x) < max_reg_before_loop
3659 && reg_iv_type[REGNO (x)] == BASIC_INDUCT)
3660 return reg_biv_class[REGNO (x)]->biv->src_reg;
3667 fmt = GET_RTX_FORMAT (code);
3668 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3671 XEXP (x, i) = remap_split_bivs (XEXP (x, i));
3675 for (j = 0; j < XVECLEN (x, i); j++)
3676 XVECEXP (x, i, j) = remap_split_bivs (XVECEXP (x, i, j));
3682 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3683 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3684 return 0. COPY_START is where we can start looking for the insns
3685 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3688 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3689 must dominate LAST_UID.
3691 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3692 may not dominate LAST_UID.
3694 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3695 must dominate LAST_UID. */
3698 set_dominates_use (regno, first_uid, last_uid, copy_start, copy_end)
3705 int passed_jump = 0;
3706 rtx p = NEXT_INSN (copy_start);
3708 while (INSN_UID (p) != first_uid)
3710 if (GET_CODE (p) == JUMP_INSN)
3712 /* Could not find FIRST_UID. */
3718 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
3719 if (GET_RTX_CLASS (GET_CODE (p)) != 'i'
3720 || ! dead_or_set_regno_p (p, regno))
3723 /* FIRST_UID is always executed. */
3724 if (passed_jump == 0)
3727 while (INSN_UID (p) != last_uid)
3729 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
3730 can not be sure that FIRST_UID dominates LAST_UID. */
3731 if (GET_CODE (p) == CODE_LABEL)
3733 /* Could not find LAST_UID, but we reached the end of the loop, so
3735 else if (p == copy_end)
3740 /* FIRST_UID is always executed if LAST_UID is executed. */