1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 93-95, 97-99, 2000 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
};
153 #include "insn-config.h"
154 #include "integrate.h"
158 #include "function.h"
163 /* This controls which loops are unrolled, and by how much we unroll
166 #ifndef MAX_UNROLLED_INSNS
167 #define MAX_UNROLLED_INSNS 100
170 /* Indexed by register number, if non-zero, then it contains a pointer
171 to a struct induction for a DEST_REG giv which has been combined with
172 one of more address givs. This is needed because whenever such a DEST_REG
173 giv is modified, we must modify the value of all split address givs
174 that were combined with this DEST_REG giv. */
176 static struct induction
**addr_combined_regs
;
178 /* Indexed by register number, if this is a splittable induction variable,
179 then this will hold the current value of the register, which depends on the
182 static rtx
*splittable_regs
;
184 /* Indexed by register number, if this is a splittable induction variable,
185 this indicates if it was made from a derived giv. */
186 static char *derived_regs
;
188 /* Indexed by register number, if this is a splittable induction variable,
189 then this will hold the number of instructions in the loop that modify
190 the induction variable. Used to ensure that only the last insn modifying
191 a split iv will update the original iv of the dest. */
193 static int *splittable_regs_updates
;
195 /* Forward declarations. */
197 static void init_reg_map
PARAMS ((struct inline_remap
*, int));
198 static rtx calculate_giv_inc
PARAMS ((rtx
, rtx
, int));
199 static rtx initial_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
200 static void final_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
201 static void copy_loop_body
PARAMS ((rtx
, rtx
, struct inline_remap
*, rtx
, int,
202 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
203 static void iteration_info
PARAMS ((const struct loop
*, rtx
, rtx
*, rtx
*));
204 static int find_splittable_regs
PARAMS ((const struct loop
*,
205 enum unroll_types
, rtx
, int));
206 static int find_splittable_givs
PARAMS ((const struct loop
*,
207 struct iv_class
*, enum unroll_types
,
209 static int reg_dead_after_loop
PARAMS ((const struct loop
*, rtx
));
210 static rtx fold_rtx_mult_add
PARAMS ((rtx
, rtx
, rtx
, enum machine_mode
));
211 static int verify_addresses
PARAMS ((struct induction
*, rtx
, int));
212 static rtx remap_split_bivs
PARAMS ((rtx
));
213 static rtx find_common_reg_term
PARAMS ((rtx
, rtx
));
214 static rtx subtract_reg_term
PARAMS ((rtx
, rtx
));
215 static rtx loop_find_equiv_value
PARAMS ((const struct loop
*, rtx
));
217 /* Try to unroll one loop and split induction variables in the loop.
219 The loop is described by the arguments LOOP and INSN_COUNT.
220 END_INSERT_BEFORE indicates where insns should be added which need
221 to be executed when the loop falls through. STRENGTH_REDUCTION_P
222 indicates whether information generated in the strength reduction
225 This function is intended to be called from within `strength_reduce'
229 unroll_loop (loop
, insn_count
, end_insert_before
, strength_reduce_p
)
232 rtx end_insert_before
;
233 int strength_reduce_p
;
236 unsigned HOST_WIDE_INT temp
;
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
;
243 char *local_label
= NULL
;
245 int max_local_regnum
;
250 int splitting_not_safe
= 0;
251 enum unroll_types unroll_type
= UNROLL_NAIVE
;
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
258 rtx loop_start
= loop
->start
;
259 rtx loop_end
= loop
->end
;
260 struct loop_info
*loop_info
= LOOP_INFO (loop
);
262 /* Don't bother unrolling huge loops. Since the minimum factor is
263 two, loops greater than one half of MAX_UNROLLED_INSNS will never
265 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
267 if (loop_dump_stream
)
268 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
272 /* When emitting debugger info, we can't unroll loops with unequal numbers
273 of block_beg and block_end notes, because that would unbalance the block
274 structure of the function. This can happen as a result of the
275 "if (foo) bar; else break;" optimization in jump.c. */
276 /* ??? Gcc has a general policy that -g is never supposed to change the code
277 that the compiler emits, so we must disable this optimization always,
278 even if debug info is not being output. This is rare, so this should
279 not be a significant performance problem. */
281 if (1 /* write_symbols != NO_DEBUG */)
283 int block_begins
= 0;
286 for (insn
= loop_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
288 if (GET_CODE (insn
) == NOTE
)
290 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
)
292 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
294 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_BEG
295 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_END
)
297 /* Note, would be nice to add code to unroll EH
298 regions, but until that time, we punt (don't
299 unroll). For the proper way of doing it, see
300 expand_inline_function. */
302 if (loop_dump_stream
)
303 fprintf (loop_dump_stream
,
304 "Unrolling failure: cannot unroll EH regions.\n");
310 if (block_begins
!= block_ends
)
312 if (loop_dump_stream
)
313 fprintf (loop_dump_stream
,
314 "Unrolling failure: Unbalanced block notes.\n");
319 /* Determine type of unroll to perform. Depends on the number of iterations
320 and the size of the loop. */
322 /* If there is no strength reduce info, then set
323 loop_info->n_iterations to zero. This can happen if
324 strength_reduce can't find any bivs in the loop. A value of zero
325 indicates that the number of iterations could not be calculated. */
327 if (! strength_reduce_p
)
328 loop_info
->n_iterations
= 0;
330 if (loop_dump_stream
&& loop_info
->n_iterations
> 0)
332 fputs ("Loop unrolling: ", loop_dump_stream
);
333 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
334 loop_info
->n_iterations
);
335 fputs (" iterations.\n", loop_dump_stream
);
338 /* Find and save a pointer to the last nonnote insn in the loop. */
340 last_loop_insn
= prev_nonnote_insn (loop_end
);
342 /* Calculate how many times to unroll the loop. Indicate whether or
343 not the loop is being completely unrolled. */
345 if (loop_info
->n_iterations
== 1)
347 /* If number of iterations is exactly 1, then eliminate the compare and
348 branch at the end of the loop since they will never be taken.
349 Then return, since no other action is needed here. */
351 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
352 don't do anything. */
354 if (GET_CODE (last_loop_insn
) == BARRIER
)
356 /* Delete the jump insn. This will delete the barrier also. */
357 delete_insn (PREV_INSN (last_loop_insn
));
359 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
362 rtx prev
= PREV_INSN (last_loop_insn
);
364 delete_insn (last_loop_insn
);
366 /* The immediately preceding insn may be a compare which must be
368 if (sets_cc0_p (prev
))
373 /* Remove the loop notes since this is no longer a loop. */
375 delete_insn (loop
->vtop
);
377 delete_insn (loop
->cont
);
379 delete_insn (loop_start
);
381 delete_insn (loop_end
);
385 else if (loop_info
->n_iterations
> 0
386 && loop_info
->n_iterations
* insn_count
< MAX_UNROLLED_INSNS
)
388 unroll_number
= loop_info
->n_iterations
;
389 unroll_type
= UNROLL_COMPLETELY
;
391 else if (loop_info
->n_iterations
> 0)
393 /* Try to factor the number of iterations. Don't bother with the
394 general case, only using 2, 3, 5, and 7 will get 75% of all
395 numbers theoretically, and almost all in practice. */
397 for (i
= 0; i
< NUM_FACTORS
; i
++)
398 factors
[i
].count
= 0;
400 temp
= loop_info
->n_iterations
;
401 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
402 while (temp
% factors
[i
].factor
== 0)
405 temp
= temp
/ factors
[i
].factor
;
408 /* Start with the larger factors first so that we generally
409 get lots of unrolling. */
413 for (i
= 3; i
>= 0; i
--)
414 while (factors
[i
].count
--)
416 if (temp
* factors
[i
].factor
< MAX_UNROLLED_INSNS
)
418 unroll_number
*= factors
[i
].factor
;
419 temp
*= factors
[i
].factor
;
425 /* If we couldn't find any factors, then unroll as in the normal
427 if (unroll_number
== 1)
429 if (loop_dump_stream
)
430 fprintf (loop_dump_stream
,
431 "Loop unrolling: No factors found.\n");
434 unroll_type
= UNROLL_MODULO
;
438 /* Default case, calculate number of times to unroll loop based on its
440 if (unroll_type
== UNROLL_NAIVE
)
442 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
444 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
450 /* Now we know how many times to unroll the loop. */
452 if (loop_dump_stream
)
453 fprintf (loop_dump_stream
,
454 "Unrolling loop %d times.\n", unroll_number
);
457 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
459 /* Loops of these types can start with jump down to the exit condition
460 in rare circumstances.
462 Consider a pair of nested loops where the inner loop is part
463 of the exit code for the outer loop.
465 In this case jump.c will not duplicate the exit test for the outer
466 loop, so it will start with a jump to the exit code.
468 Then consider if the inner loop turns out to iterate once and
469 only once. We will end up deleting the jumps associated with
470 the inner loop. However, the loop notes are not removed from
471 the instruction stream.
473 And finally assume that we can compute the number of iterations
476 In this case unroll may want to unroll the outer loop even though
477 it starts with a jump to the outer loop's exit code.
479 We could try to optimize this case, but it hardly seems worth it.
480 Just return without unrolling the loop in such cases. */
483 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
484 insn
= NEXT_INSN (insn
);
485 if (GET_CODE (insn
) == JUMP_INSN
)
489 if (unroll_type
== UNROLL_COMPLETELY
)
491 /* Completely unrolling the loop: Delete the compare and branch at
492 the end (the last two instructions). This delete must done at the
493 very end of loop unrolling, to avoid problems with calls to
494 back_branch_in_range_p, which is called by find_splittable_regs.
495 All increments of splittable bivs/givs are changed to load constant
498 copy_start
= loop_start
;
500 /* Set insert_before to the instruction immediately after the JUMP_INSN
501 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
502 the loop will be correctly handled by copy_loop_body. */
503 insert_before
= NEXT_INSN (last_loop_insn
);
505 /* Set copy_end to the insn before the jump at the end of the loop. */
506 if (GET_CODE (last_loop_insn
) == BARRIER
)
507 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
508 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
510 copy_end
= PREV_INSN (last_loop_insn
);
512 /* The instruction immediately before the JUMP_INSN may be a compare
513 instruction which we do not want to copy. */
514 if (sets_cc0_p (PREV_INSN (copy_end
)))
515 copy_end
= PREV_INSN (copy_end
);
520 /* We currently can't unroll a loop if it doesn't end with a
521 JUMP_INSN. There would need to be a mechanism that recognizes
522 this case, and then inserts a jump after each loop body, which
523 jumps to after the last loop body. */
524 if (loop_dump_stream
)
525 fprintf (loop_dump_stream
,
526 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
530 else if (unroll_type
== UNROLL_MODULO
)
532 /* Partially unrolling the loop: The compare and branch at the end
533 (the last two instructions) must remain. Don't copy the compare
534 and branch instructions at the end of the loop. Insert the unrolled
535 code immediately before the compare/branch at the end so that the
536 code will fall through to them as before. */
538 copy_start
= loop_start
;
540 /* Set insert_before to the jump insn at the end of the loop.
541 Set copy_end to before the jump insn at the end of the loop. */
542 if (GET_CODE (last_loop_insn
) == BARRIER
)
544 insert_before
= PREV_INSN (last_loop_insn
);
545 copy_end
= PREV_INSN (insert_before
);
547 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
549 insert_before
= last_loop_insn
;
551 /* The instruction immediately before the JUMP_INSN may be a compare
552 instruction which we do not want to copy or delete. */
553 if (sets_cc0_p (PREV_INSN (insert_before
)))
554 insert_before
= PREV_INSN (insert_before
);
556 copy_end
= PREV_INSN (insert_before
);
560 /* We currently can't unroll a loop if it doesn't end with a
561 JUMP_INSN. There would need to be a mechanism that recognizes
562 this case, and then inserts a jump after each loop body, which
563 jumps to after the last loop body. */
564 if (loop_dump_stream
)
565 fprintf (loop_dump_stream
,
566 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
572 /* Normal case: Must copy the compare and branch instructions at the
575 if (GET_CODE (last_loop_insn
) == BARRIER
)
577 /* Loop ends with an unconditional jump and a barrier.
578 Handle this like above, don't copy jump and barrier.
579 This is not strictly necessary, but doing so prevents generating
580 unconditional jumps to an immediately following label.
582 This will be corrected below if the target of this jump is
583 not the start_label. */
585 insert_before
= PREV_INSN (last_loop_insn
);
586 copy_end
= PREV_INSN (insert_before
);
588 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
590 /* Set insert_before to immediately after the JUMP_INSN, so that
591 NOTEs at the end of the loop will be correctly handled by
593 insert_before
= NEXT_INSN (last_loop_insn
);
594 copy_end
= last_loop_insn
;
598 /* We currently can't unroll a loop if it doesn't end with a
599 JUMP_INSN. There would need to be a mechanism that recognizes
600 this case, and then inserts a jump after each loop body, which
601 jumps to after the last loop body. */
602 if (loop_dump_stream
)
603 fprintf (loop_dump_stream
,
604 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
608 /* If copying exit test branches because they can not be eliminated,
609 then must convert the fall through case of the branch to a jump past
610 the end of the loop. Create a label to emit after the loop and save
611 it for later use. Do not use the label after the loop, if any, since
612 it might be used by insns outside the loop, or there might be insns
613 added before it later by final_[bg]iv_value which must be after
614 the real exit label. */
615 exit_label
= gen_label_rtx ();
618 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
619 insn
= NEXT_INSN (insn
);
621 if (GET_CODE (insn
) == JUMP_INSN
)
623 /* The loop starts with a jump down to the exit condition test.
624 Start copying the loop after the barrier following this
626 copy_start
= NEXT_INSN (insn
);
628 /* Splitting induction variables doesn't work when the loop is
629 entered via a jump to the bottom, because then we end up doing
630 a comparison against a new register for a split variable, but
631 we did not execute the set insn for the new register because
632 it was skipped over. */
633 splitting_not_safe
= 1;
634 if (loop_dump_stream
)
635 fprintf (loop_dump_stream
,
636 "Splitting not safe, because loop not entered at top.\n");
639 copy_start
= loop_start
;
642 /* This should always be the first label in the loop. */
643 start_label
= NEXT_INSN (copy_start
);
644 /* There may be a line number note and/or a loop continue note here. */
645 while (GET_CODE (start_label
) == NOTE
)
646 start_label
= NEXT_INSN (start_label
);
647 if (GET_CODE (start_label
) != CODE_LABEL
)
649 /* This can happen as a result of jump threading. If the first insns in
650 the loop test the same condition as the loop's backward jump, or the
651 opposite condition, then the backward jump will be modified to point
652 to elsewhere, and the loop's start label is deleted.
654 This case currently can not be handled by the loop unrolling code. */
656 if (loop_dump_stream
)
657 fprintf (loop_dump_stream
,
658 "Unrolling failure: unknown insns between BEG note and loop label.\n");
661 if (LABEL_NAME (start_label
))
663 /* The jump optimization pass must have combined the original start label
664 with a named label for a goto. We can't unroll this case because
665 jumps which go to the named label must be handled differently than
666 jumps to the loop start, and it is impossible to differentiate them
668 if (loop_dump_stream
)
669 fprintf (loop_dump_stream
,
670 "Unrolling failure: loop start label is gone\n");
674 if (unroll_type
== UNROLL_NAIVE
675 && GET_CODE (last_loop_insn
) == BARRIER
676 && GET_CODE (PREV_INSN (last_loop_insn
)) == JUMP_INSN
677 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
679 /* In this case, we must copy the jump and barrier, because they will
680 not be converted to jumps to an immediately following label. */
682 insert_before
= NEXT_INSN (last_loop_insn
);
683 copy_end
= last_loop_insn
;
686 if (unroll_type
== UNROLL_NAIVE
687 && GET_CODE (last_loop_insn
) == JUMP_INSN
688 && start_label
!= JUMP_LABEL (last_loop_insn
))
690 /* ??? The loop ends with a conditional branch that does not branch back
691 to the loop start label. In this case, we must emit an unconditional
692 branch to the loop exit after emitting the final branch.
693 copy_loop_body does not have support for this currently, so we
694 give up. It doesn't seem worthwhile to unroll anyways since
695 unrolling would increase the number of branch instructions
697 if (loop_dump_stream
)
698 fprintf (loop_dump_stream
,
699 "Unrolling failure: final conditional branch not to loop start\n");
703 /* Allocate a translation table for the labels and insn numbers.
704 They will be filled in as we copy the insns in the loop. */
706 max_labelno
= max_label_num ();
707 max_insnno
= get_max_uid ();
709 /* Various paths through the unroll code may reach the "egress" label
710 without initializing fields within the map structure.
712 To be safe, we use xcalloc to zero the memory. */
713 map
= (struct inline_remap
*) xcalloc (1, sizeof (struct inline_remap
));
715 /* Allocate the label map. */
719 map
->label_map
= (rtx
*) xmalloc (max_labelno
* sizeof (rtx
));
721 local_label
= (char *) xcalloc (max_labelno
, sizeof (char));
724 /* Search the loop and mark all local labels, i.e. the ones which have to
725 be distinct labels when copied. For all labels which might be
726 non-local, set their label_map entries to point to themselves.
727 If they happen to be local their label_map entries will be overwritten
728 before the loop body is copied. The label_map entries for local labels
729 will be set to a different value each time the loop body is copied. */
731 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
735 if (GET_CODE (insn
) == CODE_LABEL
)
736 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
737 else if (GET_CODE (insn
) == JUMP_INSN
)
739 if (JUMP_LABEL (insn
))
740 set_label_in_map (map
,
741 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)),
743 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
744 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
746 rtx pat
= PATTERN (insn
);
747 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
748 int len
= XVECLEN (pat
, diff_vec_p
);
751 for (i
= 0; i
< len
; i
++)
753 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
754 set_label_in_map (map
,
755 CODE_LABEL_NUMBER (label
),
760 else if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)))
761 set_label_in_map (map
, CODE_LABEL_NUMBER (XEXP (note
, 0)),
765 /* Allocate space for the insn map. */
767 map
->insn_map
= (rtx
*) xmalloc (max_insnno
* sizeof (rtx
));
769 /* Set this to zero, to indicate that we are doing loop unrolling,
770 not function inlining. */
771 map
->inline_target
= 0;
773 /* The register and constant maps depend on the number of registers
774 present, so the final maps can't be created until after
775 find_splittable_regs is called. However, they are needed for
776 preconditioning, so we create temporary maps when preconditioning
779 /* The preconditioning code may allocate two new pseudo registers. */
780 maxregnum
= max_reg_num ();
782 /* local_regno is only valid for regnos < max_local_regnum. */
783 max_local_regnum
= maxregnum
;
785 /* Allocate and zero out the splittable_regs and addr_combined_regs
786 arrays. These must be zeroed here because they will be used if
787 loop preconditioning is performed, and must be zero for that case.
789 It is safe to do this here, since the extra registers created by the
790 preconditioning code and find_splittable_regs will never be used
791 to access the splittable_regs[] and addr_combined_regs[] arrays. */
793 splittable_regs
= (rtx
*) xcalloc (maxregnum
, sizeof (rtx
));
794 derived_regs
= (char *) xcalloc (maxregnum
, sizeof (char));
795 splittable_regs_updates
= (int *) xcalloc (maxregnum
, sizeof (int));
797 = (struct induction
**) xcalloc (maxregnum
, sizeof (struct induction
*));
798 local_regno
= (char *) xcalloc (maxregnum
, sizeof (char));
800 /* Mark all local registers, i.e. the ones which are referenced only
802 if (INSN_UID (copy_end
) < max_uid_for_loop
)
804 int copy_start_luid
= INSN_LUID (copy_start
);
805 int copy_end_luid
= INSN_LUID (copy_end
);
807 /* If a register is used in the jump insn, we must not duplicate it
808 since it will also be used outside the loop. */
809 if (GET_CODE (copy_end
) == JUMP_INSN
)
812 /* If we have a target that uses cc0, then we also must not duplicate
813 the insn that sets cc0 before the jump insn, if one is present. */
815 if (GET_CODE (copy_end
) == JUMP_INSN
&& sets_cc0_p (PREV_INSN (copy_end
)))
819 /* If copy_start points to the NOTE that starts the loop, then we must
820 use the next luid, because invariant pseudo-regs moved out of the loop
821 have their lifetimes modified to start here, but they are not safe
823 if (copy_start
== loop_start
)
826 /* If a pseudo's lifetime is entirely contained within this loop, then we
827 can use a different pseudo in each unrolled copy of the loop. This
828 results in better code. */
829 /* We must limit the generic test to max_reg_before_loop, because only
830 these pseudo registers have valid regno_first_uid info. */
831 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_reg_before_loop
; ++j
)
832 if (REGNO_FIRST_UID (j
) > 0 && REGNO_FIRST_UID (j
) <= max_uid_for_loop
833 && uid_luid
[REGNO_FIRST_UID (j
)] >= copy_start_luid
834 && REGNO_LAST_UID (j
) > 0 && REGNO_LAST_UID (j
) <= max_uid_for_loop
835 && uid_luid
[REGNO_LAST_UID (j
)] <= copy_end_luid
)
837 /* However, we must also check for loop-carried dependencies.
838 If the value the pseudo has at the end of iteration X is
839 used by iteration X+1, then we can not use a different pseudo
840 for each unrolled copy of the loop. */
841 /* A pseudo is safe if regno_first_uid is a set, and this
842 set dominates all instructions from regno_first_uid to
844 /* ??? This check is simplistic. We would get better code if
845 this check was more sophisticated. */
846 if (set_dominates_use (j
, REGNO_FIRST_UID (j
), REGNO_LAST_UID (j
),
847 copy_start
, copy_end
))
850 if (loop_dump_stream
)
853 fprintf (loop_dump_stream
, "Marked reg %d as local\n", j
);
855 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
859 /* Givs that have been created from multiple biv increments always have
861 for (j
= first_increment_giv
; j
<= last_increment_giv
; j
++)
864 if (loop_dump_stream
)
865 fprintf (loop_dump_stream
, "Marked reg %d as local\n", j
);
869 /* If this loop requires exit tests when unrolled, check to see if we
870 can precondition the loop so as to make the exit tests unnecessary.
871 Just like variable splitting, this is not safe if the loop is entered
872 via a jump to the bottom. Also, can not do this if no strength
873 reduce info, because precondition_loop_p uses this info. */
875 /* Must copy the loop body for preconditioning before the following
876 find_splittable_regs call since that will emit insns which need to
877 be after the preconditioned loop copies, but immediately before the
878 unrolled loop copies. */
880 /* Also, it is not safe to split induction variables for the preconditioned
881 copies of the loop body. If we split induction variables, then the code
882 assumes that each induction variable can be represented as a function
883 of its initial value and the loop iteration number. This is not true
884 in this case, because the last preconditioned copy of the loop body
885 could be any iteration from the first up to the `unroll_number-1'th,
886 depending on the initial value of the iteration variable. Therefore
887 we can not split induction variables here, because we can not calculate
888 their value. Hence, this code must occur before find_splittable_regs
891 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
893 rtx initial_value
, final_value
, increment
;
894 enum machine_mode mode
;
896 if (precondition_loop_p (loop
,
897 &initial_value
, &final_value
, &increment
,
902 int abs_inc
, neg_inc
;
904 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
906 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
, maxregnum
,
908 global_const_equiv_varray
= map
->const_equiv_varray
;
910 init_reg_map (map
, maxregnum
);
912 /* Limit loop unrolling to 4, since this will make 7 copies of
914 if (unroll_number
> 4)
917 /* Save the absolute value of the increment, and also whether or
918 not it is negative. */
920 abs_inc
= INTVAL (increment
);
929 /* Calculate the difference between the final and initial values.
930 Final value may be a (plus (reg x) (const_int 1)) rtx.
931 Let the following cse pass simplify this if initial value is
934 We must copy the final and initial values here to avoid
935 improperly shared rtl. */
937 diff
= expand_binop (mode
, sub_optab
, copy_rtx (final_value
),
938 copy_rtx (initial_value
), NULL_RTX
, 0,
941 /* Now calculate (diff % (unroll * abs (increment))) by using an
943 diff
= expand_binop (GET_MODE (diff
), and_optab
, diff
,
944 GEN_INT (unroll_number
* abs_inc
- 1),
945 NULL_RTX
, 0, OPTAB_LIB_WIDEN
);
947 /* Now emit a sequence of branches to jump to the proper precond
950 labels
= (rtx
*) xmalloc (sizeof (rtx
) * unroll_number
);
951 for (i
= 0; i
< unroll_number
; i
++)
952 labels
[i
] = gen_label_rtx ();
954 /* Check for the case where the initial value is greater than or
955 equal to the final value. In that case, we want to execute
956 exactly one loop iteration. The code below will fail for this
957 case. This check does not apply if the loop has a NE
958 comparison at the end. */
960 if (loop_info
->comparison_code
!= NE
)
962 emit_cmp_and_jump_insns (initial_value
, final_value
,
964 NULL_RTX
, mode
, 0, 0, labels
[1]);
965 JUMP_LABEL (get_last_insn ()) = labels
[1];
966 LABEL_NUSES (labels
[1])++;
969 /* Assuming the unroll_number is 4, and the increment is 2, then
970 for a negative increment: for a positive increment:
971 diff = 0,1 precond 0 diff = 0,7 precond 0
972 diff = 2,3 precond 3 diff = 1,2 precond 1
973 diff = 4,5 precond 2 diff = 3,4 precond 2
974 diff = 6,7 precond 1 diff = 5,6 precond 3 */
976 /* We only need to emit (unroll_number - 1) branches here, the
977 last case just falls through to the following code. */
979 /* ??? This would give better code if we emitted a tree of branches
980 instead of the current linear list of branches. */
982 for (i
= 0; i
< unroll_number
- 1; i
++)
985 enum rtx_code cmp_code
;
987 /* For negative increments, must invert the constant compared
988 against, except when comparing against zero. */
996 cmp_const
= unroll_number
- i
;
1005 emit_cmp_and_jump_insns (diff
, GEN_INT (abs_inc
* cmp_const
),
1006 cmp_code
, NULL_RTX
, mode
, 0, 0,
1008 JUMP_LABEL (get_last_insn ()) = labels
[i
];
1009 LABEL_NUSES (labels
[i
])++;
1012 /* If the increment is greater than one, then we need another branch,
1013 to handle other cases equivalent to 0. */
1015 /* ??? This should be merged into the code above somehow to help
1016 simplify the code here, and reduce the number of branches emitted.
1017 For the negative increment case, the branch here could easily
1018 be merged with the `0' case branch above. For the positive
1019 increment case, it is not clear how this can be simplified. */
1024 enum rtx_code cmp_code
;
1028 cmp_const
= abs_inc
- 1;
1033 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
1037 emit_cmp_and_jump_insns (diff
, GEN_INT (cmp_const
), cmp_code
,
1038 NULL_RTX
, mode
, 0, 0, labels
[0]);
1039 JUMP_LABEL (get_last_insn ()) = labels
[0];
1040 LABEL_NUSES (labels
[0])++;
1043 sequence
= gen_sequence ();
1045 emit_insn_before (sequence
, loop_start
);
1047 /* Only the last copy of the loop body here needs the exit
1048 test, so set copy_end to exclude the compare/branch here,
1049 and then reset it inside the loop when get to the last
1052 if (GET_CODE (last_loop_insn
) == BARRIER
)
1053 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1054 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1056 copy_end
= PREV_INSN (last_loop_insn
);
1058 /* The immediately preceding insn may be a compare which we do not
1060 if (sets_cc0_p (PREV_INSN (copy_end
)))
1061 copy_end
= PREV_INSN (copy_end
);
1067 for (i
= 1; i
< unroll_number
; i
++)
1069 emit_label_after (labels
[unroll_number
- i
],
1070 PREV_INSN (loop_start
));
1072 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1073 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1074 (VARRAY_SIZE (map
->const_equiv_varray
)
1075 * sizeof (struct const_equiv_data
)));
1078 for (j
= 0; j
< max_labelno
; j
++)
1080 set_label_in_map (map
, j
, gen_label_rtx ());
1082 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_local_regnum
; j
++)
1085 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1086 record_base_value (REGNO (map
->reg_map
[j
]),
1087 regno_reg_rtx
[j
], 0);
1089 /* The last copy needs the compare/branch insns at the end,
1090 so reset copy_end here if the loop ends with a conditional
1093 if (i
== unroll_number
- 1)
1095 if (GET_CODE (last_loop_insn
) == BARRIER
)
1096 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1098 copy_end
= last_loop_insn
;
1101 /* None of the copies are the `last_iteration', so just
1102 pass zero for that parameter. */
1103 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, 0,
1104 unroll_type
, start_label
, loop_end
,
1105 loop_start
, copy_end
);
1107 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1109 if (GET_CODE (last_loop_insn
) == BARRIER
)
1111 insert_before
= PREV_INSN (last_loop_insn
);
1112 copy_end
= PREV_INSN (insert_before
);
1116 insert_before
= last_loop_insn
;
1118 /* The instruction immediately before the JUMP_INSN may be a compare
1119 instruction which we do not want to copy or delete. */
1120 if (sets_cc0_p (PREV_INSN (insert_before
)))
1121 insert_before
= PREV_INSN (insert_before
);
1123 copy_end
= PREV_INSN (insert_before
);
1126 /* Set unroll type to MODULO now. */
1127 unroll_type
= UNROLL_MODULO
;
1128 loop_preconditioned
= 1;
1135 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1136 the loop unless all loops are being unrolled. */
1137 if (unroll_type
== UNROLL_NAIVE
&& ! flag_unroll_all_loops
)
1139 if (loop_dump_stream
)
1140 fprintf (loop_dump_stream
, "Unrolling failure: Naive unrolling not being done.\n");
1144 /* At this point, we are guaranteed to unroll the loop. */
1146 /* Keep track of the unroll factor for the loop. */
1147 loop_info
->unroll_number
= unroll_number
;
1149 /* For each biv and giv, determine whether it can be safely split into
1150 a different variable for each unrolled copy of the loop body.
1151 We precalculate and save this info here, since computing it is
1154 Do this before deleting any instructions from the loop, so that
1155 back_branch_in_range_p will work correctly. */
1157 if (splitting_not_safe
)
1160 temp
= find_splittable_regs (loop
, unroll_type
,
1161 end_insert_before
, unroll_number
);
1163 /* find_splittable_regs may have created some new registers, so must
1164 reallocate the reg_map with the new larger size, and must realloc
1165 the constant maps also. */
1167 maxregnum
= max_reg_num ();
1168 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
1170 init_reg_map (map
, maxregnum
);
1172 if (map
->const_equiv_varray
== 0)
1173 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1174 maxregnum
+ temp
* unroll_number
* 2,
1176 global_const_equiv_varray
= map
->const_equiv_varray
;
1178 /* Search the list of bivs and givs to find ones which need to be remapped
1179 when split, and set their reg_map entry appropriately. */
1181 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
1183 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1184 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1186 /* Currently, non-reduced/final-value givs are never split. */
1187 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1188 if (REGNO (v
->src_reg
) != bl
->regno
)
1189 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1193 /* Use our current register alignment and pointer flags. */
1194 map
->regno_pointer_flag
= cfun
->emit
->regno_pointer_flag
;
1195 map
->regno_pointer_align
= cfun
->emit
->regno_pointer_align
;
1197 /* If the loop is being partially unrolled, and the iteration variables
1198 are being split, and are being renamed for the split, then must fix up
1199 the compare/jump instruction at the end of the loop to refer to the new
1200 registers. This compare isn't copied, so the registers used in it
1201 will never be replaced if it isn't done here. */
1203 if (unroll_type
== UNROLL_MODULO
)
1205 insn
= NEXT_INSN (copy_end
);
1206 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1207 PATTERN (insn
) = remap_split_bivs (PATTERN (insn
));
1210 /* For unroll_number times, make a copy of each instruction
1211 between copy_start and copy_end, and insert these new instructions
1212 before the end of the loop. */
1214 for (i
= 0; i
< unroll_number
; i
++)
1216 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1217 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1218 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1221 for (j
= 0; j
< max_labelno
; j
++)
1223 set_label_in_map (map
, j
, gen_label_rtx ());
1225 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_local_regnum
; j
++)
1228 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1229 record_base_value (REGNO (map
->reg_map
[j
]),
1230 regno_reg_rtx
[j
], 0);
1233 /* If loop starts with a branch to the test, then fix it so that
1234 it points to the test of the first unrolled copy of the loop. */
1235 if (i
== 0 && loop_start
!= copy_start
)
1237 insn
= PREV_INSN (copy_start
);
1238 pattern
= PATTERN (insn
);
1240 tem
= get_label_from_map (map
,
1242 (XEXP (SET_SRC (pattern
), 0)));
1243 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1245 /* Set the jump label so that it can be used by later loop unrolling
1247 JUMP_LABEL (insn
) = tem
;
1248 LABEL_NUSES (tem
)++;
1251 copy_loop_body (copy_start
, copy_end
, map
, exit_label
,
1252 i
== unroll_number
- 1, unroll_type
, start_label
,
1253 loop_end
, insert_before
, insert_before
);
1256 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1257 insn to be deleted. This prevents any runaway delete_insn call from
1258 more insns that it should, as it always stops at a CODE_LABEL. */
1260 /* Delete the compare and branch at the end of the loop if completely
1261 unrolling the loop. Deleting the backward branch at the end also
1262 deletes the code label at the start of the loop. This is done at
1263 the very end to avoid problems with back_branch_in_range_p. */
1265 if (unroll_type
== UNROLL_COMPLETELY
)
1266 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1268 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1270 /* Delete all of the original loop instructions. Don't delete the
1271 LOOP_BEG note, or the first code label in the loop. */
1273 insn
= NEXT_INSN (copy_start
);
1274 while (insn
!= safety_label
)
1276 /* ??? Don't delete named code labels. They will be deleted when the
1277 jump that references them is deleted. Otherwise, we end up deleting
1278 them twice, which causes them to completely disappear instead of turn
1279 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1280 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1281 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1282 associated LABEL_DECL to point to one of the new label instances. */
1283 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1284 if (insn
!= start_label
1285 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1286 && ! (GET_CODE (insn
) == NOTE
1287 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1288 insn
= delete_insn (insn
);
1290 insn
= NEXT_INSN (insn
);
1293 /* Can now delete the 'safety' label emitted to protect us from runaway
1294 delete_insn calls. */
1295 if (INSN_DELETED_P (safety_label
))
1297 delete_insn (safety_label
);
1299 /* If exit_label exists, emit it after the loop. Doing the emit here
1300 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1301 This is needed so that mostly_true_jump in reorg.c will treat jumps
1302 to this loop end label correctly, i.e. predict that they are usually
1305 emit_label_after (exit_label
, loop_end
);
1308 if (unroll_type
== UNROLL_COMPLETELY
)
1310 /* Remove the loop notes since this is no longer a loop. */
1312 delete_insn (loop
->vtop
);
1314 delete_insn (loop
->cont
);
1316 delete_insn (loop_start
);
1318 delete_insn (loop_end
);
1321 if (map
->const_equiv_varray
)
1322 VARRAY_FREE (map
->const_equiv_varray
);
1325 free (map
->label_map
);
1328 free (map
->insn_map
);
1329 free (splittable_regs
);
1330 free (derived_regs
);
1331 free (splittable_regs_updates
);
1332 free (addr_combined_regs
);
1335 free (map
->reg_map
);
1339 /* Return true if the loop can be safely, and profitably, preconditioned
1340 so that the unrolled copies of the loop body don't need exit tests.
1342 This only works if final_value, initial_value and increment can be
1343 determined, and if increment is a constant power of 2.
1344 If increment is not a power of 2, then the preconditioning modulo
1345 operation would require a real modulo instead of a boolean AND, and this
1346 is not considered `profitable'. */
1348 /* ??? If the loop is known to be executed very many times, or the machine
1349 has a very cheap divide instruction, then preconditioning is a win even
1350 when the increment is not a power of 2. Use RTX_COST to compute
1351 whether divide is cheap.
1352 ??? A divide by constant doesn't actually need a divide, look at
1353 expand_divmod. The reduced cost of this optimized modulo is not
1354 reflected in RTX_COST. */
1357 precondition_loop_p (loop
, initial_value
, final_value
, increment
, mode
)
1358 const struct loop
*loop
;
1359 rtx
*initial_value
, *final_value
, *increment
;
1360 enum machine_mode
*mode
;
1362 rtx loop_start
= loop
->start
;
1363 struct loop_info
*loop_info
= LOOP_INFO (loop
);
1365 if (loop_info
->n_iterations
> 0)
1367 *initial_value
= const0_rtx
;
1368 *increment
= const1_rtx
;
1369 *final_value
= GEN_INT (loop_info
->n_iterations
);
1372 if (loop_dump_stream
)
1374 fputs ("Preconditioning: Success, number of iterations known, ",
1376 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
1377 loop_info
->n_iterations
);
1378 fputs (".\n", loop_dump_stream
);
1383 if (loop_info
->initial_value
== 0)
1385 if (loop_dump_stream
)
1386 fprintf (loop_dump_stream
,
1387 "Preconditioning: Could not find initial value.\n");
1390 else if (loop_info
->increment
== 0)
1392 if (loop_dump_stream
)
1393 fprintf (loop_dump_stream
,
1394 "Preconditioning: Could not find increment value.\n");
1397 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1399 if (loop_dump_stream
)
1400 fprintf (loop_dump_stream
,
1401 "Preconditioning: Increment not a constant.\n");
1404 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1405 && (exact_log2 (- INTVAL (loop_info
->increment
)) < 0))
1407 if (loop_dump_stream
)
1408 fprintf (loop_dump_stream
,
1409 "Preconditioning: Increment not a constant power of 2.\n");
1413 /* Unsigned_compare and compare_dir can be ignored here, since they do
1414 not matter for preconditioning. */
1416 if (loop_info
->final_value
== 0)
1418 if (loop_dump_stream
)
1419 fprintf (loop_dump_stream
,
1420 "Preconditioning: EQ comparison loop.\n");
1424 /* Must ensure that final_value is invariant, so call
1425 loop_invariant_p to check. Before doing so, must check regno
1426 against max_reg_before_loop to make sure that the register is in
1427 the range covered by loop_invariant_p. If it isn't, then it is
1428 most likely a biv/giv which by definition are not invariant. */
1429 if ((GET_CODE (loop_info
->final_value
) == REG
1430 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1431 || (GET_CODE (loop_info
->final_value
) == PLUS
1432 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1433 || ! loop_invariant_p (loop
, loop_info
->final_value
))
1435 if (loop_dump_stream
)
1436 fprintf (loop_dump_stream
,
1437 "Preconditioning: Final value not invariant.\n");
1441 /* Fail for floating point values, since the caller of this function
1442 does not have code to deal with them. */
1443 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1444 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1446 if (loop_dump_stream
)
1447 fprintf (loop_dump_stream
,
1448 "Preconditioning: Floating point final or initial value.\n");
1452 /* Fail if loop_info->iteration_var is not live before loop_start,
1453 since we need to test its value in the preconditioning code. */
1455 if (uid_luid
[REGNO_FIRST_UID (REGNO (loop_info
->iteration_var
))]
1456 > INSN_LUID (loop_start
))
1458 if (loop_dump_stream
)
1459 fprintf (loop_dump_stream
,
1460 "Preconditioning: Iteration var not live before loop start.\n");
1464 /* Note that iteration_info biases the initial value for GIV iterators
1465 such as "while (i-- > 0)" so that we can calculate the number of
1466 iterations just like for BIV iterators.
1468 Also note that the absolute values of initial_value and
1469 final_value are unimportant as only their difference is used for
1470 calculating the number of loop iterations. */
1471 *initial_value
= loop_info
->initial_value
;
1472 *increment
= loop_info
->increment
;
1473 *final_value
= loop_info
->final_value
;
1475 /* Decide what mode to do these calculations in. Choose the larger
1476 of final_value's mode and initial_value's mode, or a full-word if
1477 both are constants. */
1478 *mode
= GET_MODE (*final_value
);
1479 if (*mode
== VOIDmode
)
1481 *mode
= GET_MODE (*initial_value
);
1482 if (*mode
== VOIDmode
)
1485 else if (*mode
!= GET_MODE (*initial_value
)
1486 && (GET_MODE_SIZE (*mode
)
1487 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1488 *mode
= GET_MODE (*initial_value
);
1491 if (loop_dump_stream
)
1492 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1497 /* All pseudo-registers must be mapped to themselves. Two hard registers
1498 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1499 REGNUM, to avoid function-inlining specific conversions of these
1500 registers. All other hard regs can not be mapped because they may be
1505 init_reg_map (map
, maxregnum
)
1506 struct inline_remap
*map
;
1511 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1512 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1513 /* Just clear the rest of the entries. */
1514 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1515 map
->reg_map
[i
] = 0;
1517 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1518 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1519 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1520 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1523 /* Strength-reduction will often emit code for optimized biv/givs which
1524 calculates their value in a temporary register, and then copies the result
1525 to the iv. This procedure reconstructs the pattern computing the iv;
1526 verifying that all operands are of the proper form.
1528 PATTERN must be the result of single_set.
1529 The return value is the amount that the giv is incremented by. */
1532 calculate_giv_inc (pattern
, src_insn
, regno
)
1533 rtx pattern
, src_insn
;
1537 rtx increment_total
= 0;
1541 /* Verify that we have an increment insn here. First check for a plus
1542 as the set source. */
1543 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1545 /* SR sometimes computes the new giv value in a temp, then copies it
1547 src_insn
= PREV_INSN (src_insn
);
1548 pattern
= PATTERN (src_insn
);
1549 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1552 /* The last insn emitted is not needed, so delete it to avoid confusing
1553 the second cse pass. This insn sets the giv unnecessarily. */
1554 delete_insn (get_last_insn ());
1557 /* Verify that we have a constant as the second operand of the plus. */
1558 increment
= XEXP (SET_SRC (pattern
), 1);
1559 if (GET_CODE (increment
) != CONST_INT
)
1561 /* SR sometimes puts the constant in a register, especially if it is
1562 too big to be an add immed operand. */
1563 src_insn
= PREV_INSN (src_insn
);
1564 increment
= SET_SRC (PATTERN (src_insn
));
1566 /* SR may have used LO_SUM to compute the constant if it is too large
1567 for a load immed operand. In this case, the constant is in operand
1568 one of the LO_SUM rtx. */
1569 if (GET_CODE (increment
) == LO_SUM
)
1570 increment
= XEXP (increment
, 1);
1572 /* Some ports store large constants in memory and add a REG_EQUAL
1573 note to the store insn. */
1574 else if (GET_CODE (increment
) == MEM
)
1576 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1578 increment
= XEXP (note
, 0);
1581 else if (GET_CODE (increment
) == IOR
1582 || GET_CODE (increment
) == ASHIFT
1583 || GET_CODE (increment
) == PLUS
)
1585 /* The rs6000 port loads some constants with IOR.
1586 The alpha port loads some constants with ASHIFT and PLUS. */
1587 rtx second_part
= XEXP (increment
, 1);
1588 enum rtx_code code
= GET_CODE (increment
);
1590 src_insn
= PREV_INSN (src_insn
);
1591 increment
= SET_SRC (PATTERN (src_insn
));
1592 /* Don't need the last insn anymore. */
1593 delete_insn (get_last_insn ());
1595 if (GET_CODE (second_part
) != CONST_INT
1596 || GET_CODE (increment
) != CONST_INT
)
1600 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1601 else if (code
== PLUS
)
1602 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1604 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1607 if (GET_CODE (increment
) != CONST_INT
)
1610 /* The insn loading the constant into a register is no longer needed,
1612 delete_insn (get_last_insn ());
1615 if (increment_total
)
1616 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1618 increment_total
= increment
;
1620 /* Check that the source register is the same as the register we expected
1621 to see as the source. If not, something is seriously wrong. */
1622 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1623 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1625 /* Some machines (e.g. the romp), may emit two add instructions for
1626 certain constants, so lets try looking for another add immediately
1627 before this one if we have only seen one add insn so far. */
1633 src_insn
= PREV_INSN (src_insn
);
1634 pattern
= PATTERN (src_insn
);
1636 delete_insn (get_last_insn ());
1644 return increment_total
;
1647 /* Copy REG_NOTES, except for insn references, because not all insn_map
1648 entries are valid yet. We do need to copy registers now though, because
1649 the reg_map entries can change during copying. */
1652 initial_reg_note_copy (notes
, map
)
1654 struct inline_remap
*map
;
1661 copy
= rtx_alloc (GET_CODE (notes
));
1662 PUT_MODE (copy
, GET_MODE (notes
));
1664 if (GET_CODE (notes
) == EXPR_LIST
)
1665 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
, 0);
1666 else if (GET_CODE (notes
) == INSN_LIST
)
1667 /* Don't substitute for these yet. */
1668 XEXP (copy
, 0) = XEXP (notes
, 0);
1672 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1677 /* Fixup insn references in copied REG_NOTES. */
1680 final_reg_note_copy (notes
, map
)
1682 struct inline_remap
*map
;
1686 for (note
= notes
; note
; note
= XEXP (note
, 1))
1687 if (GET_CODE (note
) == INSN_LIST
)
1688 XEXP (note
, 0) = map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1691 /* Copy each instruction in the loop, substituting from map as appropriate.
1692 This is very similar to a loop in expand_inline_function. */
1695 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1696 unroll_type
, start_label
, loop_end
, insert_before
,
1698 rtx copy_start
, copy_end
;
1699 struct inline_remap
*map
;
1702 enum unroll_types unroll_type
;
1703 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1706 rtx set
, tem
, copy
= NULL_RTX
;
1707 int dest_reg_was_split
, i
;
1711 rtx final_label
= 0;
1712 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1714 /* If this isn't the last iteration, then map any references to the
1715 start_label to final_label. Final label will then be emitted immediately
1716 after the end of this loop body if it was ever used.
1718 If this is the last iteration, then map references to the start_label
1720 if (! last_iteration
)
1722 final_label
= gen_label_rtx ();
1723 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
),
1727 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1731 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1732 Else gen_sequence could return a raw pattern for a jump which we pass
1733 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1734 a variety of losing behaviors later. */
1735 emit_note (0, NOTE_INSN_DELETED
);
1740 insn
= NEXT_INSN (insn
);
1742 map
->orig_asm_operands_vector
= 0;
1744 switch (GET_CODE (insn
))
1747 pattern
= PATTERN (insn
);
1751 /* Check to see if this is a giv that has been combined with
1752 some split address givs. (Combined in the sense that
1753 `combine_givs' in loop.c has put two givs in the same register.)
1754 In this case, we must search all givs based on the same biv to
1755 find the address givs. Then split the address givs.
1756 Do this before splitting the giv, since that may map the
1757 SET_DEST to a new register. */
1759 if ((set
= single_set (insn
))
1760 && GET_CODE (SET_DEST (set
)) == REG
1761 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1763 struct iv_class
*bl
;
1764 struct induction
*v
, *tv
;
1765 int regno
= REGNO (SET_DEST (set
));
1767 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1768 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
1770 /* Although the giv_inc amount is not needed here, we must call
1771 calculate_giv_inc here since it might try to delete the
1772 last insn emitted. If we wait until later to call it,
1773 we might accidentally delete insns generated immediately
1774 below by emit_unrolled_add. */
1776 if (! derived_regs
[regno
])
1777 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1779 /* Now find all address giv's that were combined with this
1781 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1782 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1786 /* If this DEST_ADDR giv was not split, then ignore it. */
1787 if (*tv
->location
!= tv
->dest_reg
)
1790 /* Scale this_giv_inc if the multiplicative factors of
1791 the two givs are different. */
1792 this_giv_inc
= INTVAL (giv_inc
);
1793 if (tv
->mult_val
!= v
->mult_val
)
1794 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1795 * INTVAL (tv
->mult_val
));
1797 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1798 *tv
->location
= tv
->dest_reg
;
1800 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1802 /* Must emit an insn to increment the split address
1803 giv. Add in the const_adjust field in case there
1804 was a constant eliminated from the address. */
1805 rtx value
, dest_reg
;
1807 /* tv->dest_reg will be either a bare register,
1808 or else a register plus a constant. */
1809 if (GET_CODE (tv
->dest_reg
) == REG
)
1810 dest_reg
= tv
->dest_reg
;
1812 dest_reg
= XEXP (tv
->dest_reg
, 0);
1814 /* Check for shared address givs, and avoid
1815 incrementing the shared pseudo reg more than
1817 if (! tv
->same_insn
&& ! tv
->shared
)
1819 /* tv->dest_reg may actually be a (PLUS (REG)
1820 (CONST)) here, so we must call plus_constant
1821 to add the const_adjust amount before calling
1822 emit_unrolled_add below. */
1823 value
= plus_constant (tv
->dest_reg
,
1826 if (GET_CODE (value
) == PLUS
)
1828 /* The constant could be too large for an add
1829 immediate, so can't directly emit an insn
1831 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1836 /* Reset the giv to be just the register again, in case
1837 it is used after the set we have just emitted.
1838 We must subtract the const_adjust factor added in
1840 tv
->dest_reg
= plus_constant (dest_reg
,
1841 - tv
->const_adjust
);
1842 *tv
->location
= tv
->dest_reg
;
1847 /* If this is a setting of a splittable variable, then determine
1848 how to split the variable, create a new set based on this split,
1849 and set up the reg_map so that later uses of the variable will
1850 use the new split variable. */
1852 dest_reg_was_split
= 0;
1854 if ((set
= single_set (insn
))
1855 && GET_CODE (SET_DEST (set
)) == REG
1856 && splittable_regs
[REGNO (SET_DEST (set
))])
1858 int regno
= REGNO (SET_DEST (set
));
1861 dest_reg_was_split
= 1;
1863 giv_dest_reg
= SET_DEST (set
);
1864 if (derived_regs
[regno
])
1866 /* ??? This relies on SET_SRC (SET) to be of
1867 the form (plus (reg) (const_int)), and thus
1868 forces recombine_givs to restrict the kind
1869 of giv derivations it does before unrolling. */
1870 giv_src_reg
= XEXP (SET_SRC (set
), 0);
1871 giv_inc
= XEXP (SET_SRC (set
), 1);
1875 giv_src_reg
= giv_dest_reg
;
1876 /* Compute the increment value for the giv, if it wasn't
1877 already computed above. */
1879 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1881 src_regno
= REGNO (giv_src_reg
);
1883 if (unroll_type
== UNROLL_COMPLETELY
)
1885 /* Completely unrolling the loop. Set the induction
1886 variable to a known constant value. */
1888 /* The value in splittable_regs may be an invariant
1889 value, so we must use plus_constant here. */
1890 splittable_regs
[regno
]
1891 = plus_constant (splittable_regs
[src_regno
],
1894 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1896 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1897 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1901 /* The splittable_regs value must be a REG or a
1902 CONST_INT, so put the entire value in the giv_src_reg
1904 giv_src_reg
= splittable_regs
[regno
];
1905 giv_inc
= const0_rtx
;
1910 /* Partially unrolling loop. Create a new pseudo
1911 register for the iteration variable, and set it to
1912 be a constant plus the original register. Except
1913 on the last iteration, when the result has to
1914 go back into the original iteration var register. */
1916 /* Handle bivs which must be mapped to a new register
1917 when split. This happens for bivs which need their
1918 final value set before loop entry. The new register
1919 for the biv was stored in the biv's first struct
1920 induction entry by find_splittable_regs. */
1922 if (regno
< max_reg_before_loop
1923 && REG_IV_TYPE (regno
) == BASIC_INDUCT
)
1925 giv_src_reg
= reg_biv_class
[regno
]->biv
->src_reg
;
1926 giv_dest_reg
= giv_src_reg
;
1930 /* If non-reduced/final-value givs were split, then
1931 this would have to remap those givs also. See
1932 find_splittable_regs. */
1935 splittable_regs
[regno
]
1936 = GEN_INT (INTVAL (giv_inc
)
1937 + INTVAL (splittable_regs
[src_regno
]));
1938 giv_inc
= splittable_regs
[regno
];
1940 /* Now split the induction variable by changing the dest
1941 of this insn to a new register, and setting its
1942 reg_map entry to point to this new register.
1944 If this is the last iteration, and this is the last insn
1945 that will update the iv, then reuse the original dest,
1946 to ensure that the iv will have the proper value when
1947 the loop exits or repeats.
1949 Using splittable_regs_updates here like this is safe,
1950 because it can only be greater than one if all
1951 instructions modifying the iv are always executed in
1954 if (! last_iteration
1955 || (splittable_regs_updates
[regno
]-- != 1))
1957 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
1959 map
->reg_map
[regno
] = tem
;
1960 record_base_value (REGNO (tem
),
1961 giv_inc
== const0_rtx
1963 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
1964 giv_src_reg
, giv_inc
),
1968 map
->reg_map
[regno
] = giv_src_reg
;
1971 /* The constant being added could be too large for an add
1972 immediate, so can't directly emit an insn here. */
1973 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
1974 copy
= get_last_insn ();
1975 pattern
= PATTERN (copy
);
1979 pattern
= copy_rtx_and_substitute (pattern
, map
, 0);
1980 copy
= emit_insn (pattern
);
1982 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1985 /* If this insn is setting CC0, it may need to look at
1986 the insn that uses CC0 to see what type of insn it is.
1987 In that case, the call to recog via validate_change will
1988 fail. So don't substitute constants here. Instead,
1989 do it when we emit the following insn.
1991 For example, see the pyr.md file. That machine has signed and
1992 unsigned compares. The compare patterns must check the
1993 following branch insn to see which what kind of compare to
1996 If the previous insn set CC0, substitute constants on it as
1998 if (sets_cc0_p (PATTERN (copy
)) != 0)
2003 try_constants (cc0_insn
, map
);
2005 try_constants (copy
, map
);
2008 try_constants (copy
, map
);
2011 /* Make split induction variable constants `permanent' since we
2012 know there are no backward branches across iteration variable
2013 settings which would invalidate this. */
2014 if (dest_reg_was_split
)
2016 int regno
= REGNO (SET_DEST (set
));
2018 if ((size_t) regno
< VARRAY_SIZE (map
->const_equiv_varray
)
2019 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
2021 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
2026 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2027 copy
= emit_jump_insn (pattern
);
2028 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2030 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
2031 && ! last_iteration
)
2033 /* This is a branch to the beginning of the loop; this is the
2034 last insn being copied; and this is not the last iteration.
2035 In this case, we want to change the original fall through
2036 case to be a branch past the end of the loop, and the
2037 original jump label case to fall_through. */
2039 if (invert_exp (pattern
, copy
))
2041 if (! redirect_exp (&pattern
,
2042 get_label_from_map (map
,
2044 (JUMP_LABEL (insn
))),
2051 rtx lab
= gen_label_rtx ();
2052 /* Can't do it by reversing the jump (probably because we
2053 couldn't reverse the conditions), so emit a new
2054 jump_insn after COPY, and redirect the jump around
2056 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2057 jmp
= emit_barrier_after (jmp
);
2058 emit_label_after (lab
, jmp
);
2059 LABEL_NUSES (lab
) = 0;
2060 if (! redirect_exp (&pattern
,
2061 get_label_from_map (map
,
2063 (JUMP_LABEL (insn
))),
2071 try_constants (cc0_insn
, map
);
2074 try_constants (copy
, map
);
2076 /* Set the jump label of COPY correctly to avoid problems with
2077 later passes of unroll_loop, if INSN had jump label set. */
2078 if (JUMP_LABEL (insn
))
2082 /* Can't use the label_map for every insn, since this may be
2083 the backward branch, and hence the label was not mapped. */
2084 if ((set
= single_set (copy
)))
2086 tem
= SET_SRC (set
);
2087 if (GET_CODE (tem
) == LABEL_REF
)
2088 label
= XEXP (tem
, 0);
2089 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2091 if (XEXP (tem
, 1) != pc_rtx
)
2092 label
= XEXP (XEXP (tem
, 1), 0);
2094 label
= XEXP (XEXP (tem
, 2), 0);
2098 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2099 JUMP_LABEL (copy
) = label
;
2102 /* An unrecognizable jump insn, probably the entry jump
2103 for a switch statement. This label must have been mapped,
2104 so just use the label_map to get the new jump label. */
2106 = get_label_from_map (map
,
2107 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2110 /* If this is a non-local jump, then must increase the label
2111 use count so that the label will not be deleted when the
2112 original jump is deleted. */
2113 LABEL_NUSES (JUMP_LABEL (copy
))++;
2115 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2116 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2118 rtx pat
= PATTERN (copy
);
2119 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2120 int len
= XVECLEN (pat
, diff_vec_p
);
2123 for (i
= 0; i
< len
; i
++)
2124 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2127 /* If this used to be a conditional jump insn but whose branch
2128 direction is now known, we must do something special. */
2129 if (condjump_p (insn
) && !simplejump_p (insn
) && map
->last_pc_value
)
2132 /* If the previous insn set cc0 for us, delete it. */
2133 if (sets_cc0_p (PREV_INSN (copy
)))
2134 delete_insn (PREV_INSN (copy
));
2137 /* If this is now a no-op, delete it. */
2138 if (map
->last_pc_value
== pc_rtx
)
2140 /* Don't let delete_insn delete the label referenced here,
2141 because we might possibly need it later for some other
2142 instruction in the loop. */
2143 if (JUMP_LABEL (copy
))
2144 LABEL_NUSES (JUMP_LABEL (copy
))++;
2146 if (JUMP_LABEL (copy
))
2147 LABEL_NUSES (JUMP_LABEL (copy
))--;
2151 /* Otherwise, this is unconditional jump so we must put a
2152 BARRIER after it. We could do some dead code elimination
2153 here, but jump.c will do it just as well. */
2159 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2160 copy
= emit_call_insn (pattern
);
2161 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2163 /* Because the USAGE information potentially contains objects other
2164 than hard registers, we need to copy it. */
2165 CALL_INSN_FUNCTION_USAGE (copy
)
2166 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
),
2171 try_constants (cc0_insn
, map
);
2174 try_constants (copy
, map
);
2176 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2177 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2178 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2182 /* If this is the loop start label, then we don't need to emit a
2183 copy of this label since no one will use it. */
2185 if (insn
!= start_label
)
2187 copy
= emit_label (get_label_from_map (map
,
2188 CODE_LABEL_NUMBER (insn
)));
2194 copy
= emit_barrier ();
2198 /* VTOP and CONT notes are valid only before the loop exit test.
2199 If placed anywhere else, loop may generate bad code. */
2200 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2201 the associated rtl. We do not want to share the structure in
2204 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2205 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2206 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2207 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2208 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2209 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2210 NOTE_LINE_NUMBER (insn
));
2219 map
->insn_map
[INSN_UID (insn
)] = copy
;
2221 while (insn
!= copy_end
);
2223 /* Now finish coping the REG_NOTES. */
2227 insn
= NEXT_INSN (insn
);
2228 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2229 || GET_CODE (insn
) == CALL_INSN
)
2230 && map
->insn_map
[INSN_UID (insn
)])
2231 final_reg_note_copy (REG_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2233 while (insn
!= copy_end
);
2235 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2236 each of these notes here, since there may be some important ones, such as
2237 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2238 iteration, because the original notes won't be deleted.
2240 We can't use insert_before here, because when from preconditioning,
2241 insert_before points before the loop. We can't use copy_end, because
2242 there may be insns already inserted after it (which we don't want to
2243 copy) when not from preconditioning code. */
2245 if (! last_iteration
)
2247 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2249 /* VTOP notes are valid only before the loop exit test.
2250 If placed anywhere else, loop may generate bad code.
2251 There is no need to test for NOTE_INSN_LOOP_CONT notes
2252 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2253 instructions before the last insn in the loop, and if the
2254 end test is that short, there will be a VTOP note between
2255 the CONT note and the test. */
2256 if (GET_CODE (insn
) == NOTE
2257 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2258 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2259 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
)
2260 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2264 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2265 emit_label (final_label
);
2267 tem
= gen_sequence ();
2269 emit_insn_before (tem
, insert_before
);
2272 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2273 emitted. This will correctly handle the case where the increment value
2274 won't fit in the immediate field of a PLUS insns. */
2277 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2278 rtx dest_reg
, src_reg
, increment
;
2282 result
= expand_binop (GET_MODE (dest_reg
), add_optab
, src_reg
, increment
,
2283 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2285 if (dest_reg
!= result
)
2286 emit_move_insn (dest_reg
, result
);
2289 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2290 is a backward branch in that range that branches to somewhere between
2291 LOOP->START and INSN. Returns 0 otherwise. */
2293 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2294 In practice, this is not a problem, because this function is seldom called,
2295 and uses a negligible amount of CPU time on average. */
2298 back_branch_in_range_p (loop
, insn
)
2299 const struct loop
*loop
;
2302 rtx p
, q
, target_insn
;
2303 rtx loop_start
= loop
->start
;
2304 rtx loop_end
= loop
->end
;
2305 rtx orig_loop_end
= loop
->end
;
2307 /* Stop before we get to the backward branch at the end of the loop. */
2308 loop_end
= prev_nonnote_insn (loop_end
);
2309 if (GET_CODE (loop_end
) == BARRIER
)
2310 loop_end
= PREV_INSN (loop_end
);
2312 /* Check in case insn has been deleted, search forward for first non
2313 deleted insn following it. */
2314 while (INSN_DELETED_P (insn
))
2315 insn
= NEXT_INSN (insn
);
2317 /* Check for the case where insn is the last insn in the loop. Deal
2318 with the case where INSN was a deleted loop test insn, in which case
2319 it will now be the NOTE_LOOP_END. */
2320 if (insn
== loop_end
|| insn
== orig_loop_end
)
2323 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2325 if (GET_CODE (p
) == JUMP_INSN
)
2327 target_insn
= JUMP_LABEL (p
);
2329 /* Search from loop_start to insn, to see if one of them is
2330 the target_insn. We can't use INSN_LUID comparisons here,
2331 since insn may not have an LUID entry. */
2332 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2333 if (q
== target_insn
)
2341 /* Try to generate the simplest rtx for the expression
2342 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2346 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2347 rtx mult1
, mult2
, add1
;
2348 enum machine_mode mode
;
2353 /* The modes must all be the same. This should always be true. For now,
2354 check to make sure. */
2355 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2356 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2357 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2360 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2361 will be a constant. */
2362 if (GET_CODE (mult1
) == CONST_INT
)
2369 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2371 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2373 /* Again, put the constant second. */
2374 if (GET_CODE (add1
) == CONST_INT
)
2381 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2383 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2388 /* Searches the list of induction struct's for the biv BL, to try to calculate
2389 the total increment value for one iteration of the loop as a constant.
2391 Returns the increment value as an rtx, simplified as much as possible,
2392 if it can be calculated. Otherwise, returns 0. */
2395 biv_total_increment (bl
)
2396 struct iv_class
*bl
;
2398 struct induction
*v
;
2401 /* For increment, must check every instruction that sets it. Each
2402 instruction must be executed only once each time through the loop.
2403 To verify this, we check that the insn is always executed, and that
2404 there are no backward branches after the insn that branch to before it.
2405 Also, the insn must have a mult_val of one (to make sure it really is
2408 result
= const0_rtx
;
2409 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2411 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2412 && ! v
->maybe_multiple
)
2413 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2421 /* Determine the initial value of the iteration variable, and the amount
2422 that it is incremented each loop. Use the tables constructed by
2423 the strength reduction pass to calculate these values.
2425 Initial_value and/or increment are set to zero if their values could not
2429 iteration_info (loop
, iteration_var
, initial_value
, increment
)
2430 const struct loop
*loop ATTRIBUTE_UNUSED
;
2431 rtx iteration_var
, *initial_value
, *increment
;
2433 struct iv_class
*bl
;
2435 /* Clear the result values, in case no answer can be found. */
2439 /* The iteration variable can be either a giv or a biv. Check to see
2440 which it is, and compute the variable's initial value, and increment
2441 value if possible. */
2443 /* If this is a new register, can't handle it since we don't have any
2444 reg_iv_type entry for it. */
2445 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
)
2447 if (loop_dump_stream
)
2448 fprintf (loop_dump_stream
,
2449 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2453 /* Reject iteration variables larger than the host wide int size, since they
2454 could result in a number of iterations greater than the range of our
2455 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2456 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
2457 > HOST_BITS_PER_WIDE_INT
))
2459 if (loop_dump_stream
)
2460 fprintf (loop_dump_stream
,
2461 "Loop unrolling: Iteration var rejected because mode too large.\n");
2464 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
2466 if (loop_dump_stream
)
2467 fprintf (loop_dump_stream
,
2468 "Loop unrolling: Iteration var not an integer.\n");
2471 else if (REG_IV_TYPE (REGNO (iteration_var
)) == BASIC_INDUCT
)
2473 /* When reg_iv_type / reg_iv_info is resized for biv increments
2474 that are turned into givs, reg_biv_class is not resized.
2475 So check here that we don't make an out-of-bounds access. */
2476 if (REGNO (iteration_var
) >= max_reg_before_loop
)
2479 /* Grab initial value, only useful if it is a constant. */
2480 bl
= reg_biv_class
[REGNO (iteration_var
)];
2481 *initial_value
= bl
->initial_value
;
2483 *increment
= biv_total_increment (bl
);
2485 else if (REG_IV_TYPE (REGNO (iteration_var
)) == GENERAL_INDUCT
)
2487 HOST_WIDE_INT offset
= 0;
2488 struct induction
*v
= REG_IV_INFO (REGNO (iteration_var
));
2490 if (REGNO (v
->src_reg
) >= max_reg_before_loop
)
2493 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
2495 /* Increment value is mult_val times the increment value of the biv. */
2497 *increment
= biv_total_increment (bl
);
2500 struct induction
*biv_inc
;
2503 = fold_rtx_mult_add (v
->mult_val
, *increment
, const0_rtx
, v
->mode
);
2504 /* The caller assumes that one full increment has occured at the
2505 first loop test. But that's not true when the biv is incremented
2506 after the giv is set (which is the usual case), e.g.:
2507 i = 6; do {;} while (i++ < 9) .
2508 Therefore, we bias the initial value by subtracting the amount of
2509 the increment that occurs between the giv set and the giv test. */
2510 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
2512 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
2513 offset
-= INTVAL (biv_inc
->add_val
);
2515 offset
*= INTVAL (v
->mult_val
);
2517 if (loop_dump_stream
)
2518 fprintf (loop_dump_stream
,
2519 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2521 /* Initial value is mult_val times the biv's initial value plus
2522 add_val. Only useful if it is a constant. */
2524 = fold_rtx_mult_add (v
->mult_val
,
2525 plus_constant (bl
->initial_value
, offset
),
2526 v
->add_val
, v
->mode
);
2530 if (loop_dump_stream
)
2531 fprintf (loop_dump_stream
,
2532 "Loop unrolling: Not basic or general induction var.\n");
2538 /* For each biv and giv, determine whether it can be safely split into
2539 a different variable for each unrolled copy of the loop body. If it
2540 is safe to split, then indicate that by saving some useful info
2541 in the splittable_regs array.
2543 If the loop is being completely unrolled, then splittable_regs will hold
2544 the current value of the induction variable while the loop is unrolled.
2545 It must be set to the initial value of the induction variable here.
2546 Otherwise, splittable_regs will hold the difference between the current
2547 value of the induction variable and the value the induction variable had
2548 at the top of the loop. It must be set to the value 0 here.
2550 Returns the total number of instructions that set registers that are
2553 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2554 constant values are unnecessary, since we can easily calculate increment
2555 values in this case even if nothing is constant. The increment value
2556 should not involve a multiply however. */
2558 /* ?? Even if the biv/giv increment values aren't constant, it may still
2559 be beneficial to split the variable if the loop is only unrolled a few
2560 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2563 find_splittable_regs (loop
, unroll_type
, end_insert_before
, unroll_number
)
2564 const struct loop
*loop
;
2565 enum unroll_types unroll_type
;
2566 rtx end_insert_before
;
2569 struct iv_class
*bl
;
2570 struct induction
*v
;
2572 rtx biv_final_value
;
2575 rtx loop_start
= loop
->start
;
2576 rtx loop_end
= loop
->end
;
2578 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
2580 /* Biv_total_increment must return a constant value,
2581 otherwise we can not calculate the split values. */
2583 increment
= biv_total_increment (bl
);
2584 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2587 /* The loop must be unrolled completely, or else have a known number
2588 of iterations and only one exit, or else the biv must be dead
2589 outside the loop, or else the final value must be known. Otherwise,
2590 it is unsafe to split the biv since it may not have the proper
2591 value on loop exit. */
2593 /* loop_number_exit_count is non-zero if the loop has an exit other than
2594 a fall through at the end. */
2597 biv_final_value
= 0;
2598 if (unroll_type
!= UNROLL_COMPLETELY
2599 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2600 && (uid_luid
[REGNO_LAST_UID (bl
->regno
)] >= INSN_LUID (loop_end
)
2602 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2603 || (uid_luid
[REGNO_FIRST_UID (bl
->regno
)]
2604 < INSN_LUID (bl
->init_insn
))
2605 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2606 && ! (biv_final_value
= final_biv_value (loop
, bl
)))
2609 /* If any of the insns setting the BIV don't do so with a simple
2610 PLUS, we don't know how to split it. */
2611 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2612 if ((tem
= single_set (v
->insn
)) == 0
2613 || GET_CODE (SET_DEST (tem
)) != REG
2614 || REGNO (SET_DEST (tem
)) != bl
->regno
2615 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2618 /* If final value is non-zero, then must emit an instruction which sets
2619 the value of the biv to the proper value. This is done after
2620 handling all of the givs, since some of them may need to use the
2621 biv's value in their initialization code. */
2623 /* This biv is splittable. If completely unrolling the loop, save
2624 the biv's initial value. Otherwise, save the constant zero. */
2626 if (biv_splittable
== 1)
2628 if (unroll_type
== UNROLL_COMPLETELY
)
2630 /* If the initial value of the biv is itself (i.e. it is too
2631 complicated for strength_reduce to compute), or is a hard
2632 register, or it isn't invariant, then we must create a new
2633 pseudo reg to hold the initial value of the biv. */
2635 if (GET_CODE (bl
->initial_value
) == REG
2636 && (REGNO (bl
->initial_value
) == bl
->regno
2637 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2638 || ! loop_invariant_p (loop
, bl
->initial_value
)))
2640 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2642 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2643 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2646 if (loop_dump_stream
)
2647 fprintf (loop_dump_stream
, "Biv %d initial value remapped to %d.\n",
2648 bl
->regno
, REGNO (tem
));
2650 splittable_regs
[bl
->regno
] = tem
;
2653 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2656 splittable_regs
[bl
->regno
] = const0_rtx
;
2658 /* Save the number of instructions that modify the biv, so that
2659 we can treat the last one specially. */
2661 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2662 result
+= bl
->biv_count
;
2664 if (loop_dump_stream
)
2665 fprintf (loop_dump_stream
,
2666 "Biv %d safe to split.\n", bl
->regno
);
2669 /* Check every giv that depends on this biv to see whether it is
2670 splittable also. Even if the biv isn't splittable, givs which
2671 depend on it may be splittable if the biv is live outside the
2672 loop, and the givs aren't. */
2674 result
+= find_splittable_givs (loop
, bl
, unroll_type
, increment
,
2677 /* If final value is non-zero, then must emit an instruction which sets
2678 the value of the biv to the proper value. This is done after
2679 handling all of the givs, since some of them may need to use the
2680 biv's value in their initialization code. */
2681 if (biv_final_value
)
2683 /* If the loop has multiple exits, emit the insns before the
2684 loop to ensure that it will always be executed no matter
2685 how the loop exits. Otherwise emit the insn after the loop,
2686 since this is slightly more efficient. */
2687 if (! loop
->exit_count
)
2688 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2693 /* Create a new register to hold the value of the biv, and then
2694 set the biv to its final value before the loop start. The biv
2695 is set to its final value before loop start to ensure that
2696 this insn will always be executed, no matter how the loop
2698 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2699 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2701 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2703 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2707 if (loop_dump_stream
)
2708 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2709 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2711 /* Set up the mapping from the original biv register to the new
2713 bl
->biv
->src_reg
= tem
;
2720 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2721 for the instruction that is using it. Do not make any changes to that
2725 verify_addresses (v
, giv_inc
, unroll_number
)
2726 struct induction
*v
;
2731 rtx orig_addr
= *v
->location
;
2732 rtx last_addr
= plus_constant (v
->dest_reg
,
2733 INTVAL (giv_inc
) * (unroll_number
- 1));
2735 /* First check to see if either address would fail. Handle the fact
2736 that we have may have a match_dup. */
2737 if (! validate_replace_rtx (*v
->location
, v
->dest_reg
, v
->insn
)
2738 || ! validate_replace_rtx (*v
->location
, last_addr
, v
->insn
))
2741 /* Now put things back the way they were before. This should always
2743 if (! validate_replace_rtx (*v
->location
, orig_addr
, v
->insn
))
2749 /* For every giv based on the biv BL, check to determine whether it is
2750 splittable. This is a subroutine to find_splittable_regs ().
2752 Return the number of instructions that set splittable registers. */
2755 find_splittable_givs (loop
, bl
, unroll_type
, increment
, unroll_number
)
2756 const struct loop
*loop
;
2757 struct iv_class
*bl
;
2758 enum unroll_types unroll_type
;
2762 struct induction
*v
, *v2
;
2767 /* Scan the list of givs, and set the same_insn field when there are
2768 multiple identical givs in the same insn. */
2769 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2770 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2771 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2775 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2779 /* Only split the giv if it has already been reduced, or if the loop is
2780 being completely unrolled. */
2781 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2784 /* The giv can be split if the insn that sets the giv is executed once
2785 and only once on every iteration of the loop. */
2786 /* An address giv can always be split. v->insn is just a use not a set,
2787 and hence it does not matter whether it is always executed. All that
2788 matters is that all the biv increments are always executed, and we
2789 won't reach here if they aren't. */
2790 if (v
->giv_type
!= DEST_ADDR
2791 && (! v
->always_computable
2792 || back_branch_in_range_p (loop
, v
->insn
)))
2795 /* The giv increment value must be a constant. */
2796 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2798 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2801 /* The loop must be unrolled completely, or else have a known number of
2802 iterations and only one exit, or else the giv must be dead outside
2803 the loop, or else the final value of the giv must be known.
2804 Otherwise, it is not safe to split the giv since it may not have the
2805 proper value on loop exit. */
2807 /* The used outside loop test will fail for DEST_ADDR givs. They are
2808 never used outside the loop anyways, so it is always safe to split a
2812 if (unroll_type
!= UNROLL_COMPLETELY
2813 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2814 && v
->giv_type
!= DEST_ADDR
2815 /* The next part is true if the pseudo is used outside the loop.
2816 We assume that this is true for any pseudo created after loop
2817 starts, because we don't have a reg_n_info entry for them. */
2818 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2819 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2820 /* Check for the case where the pseudo is set by a shift/add
2821 sequence, in which case the first insn setting the pseudo
2822 is the first insn of the shift/add sequence. */
2823 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2824 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2825 != INSN_UID (XEXP (tem
, 0)))))
2826 /* Line above always fails if INSN was moved by loop opt. */
2827 || (uid_luid
[REGNO_LAST_UID (REGNO (v
->dest_reg
))]
2828 >= INSN_LUID (loop
->end
)))
2829 /* Givs made from biv increments are missed by the above test, so
2830 test explicitly for them. */
2831 && (REGNO (v
->dest_reg
) < first_increment_giv
2832 || REGNO (v
->dest_reg
) > last_increment_giv
)
2833 && ! (final_value
= v
->final_value
))
2837 /* Currently, non-reduced/final-value givs are never split. */
2838 /* Should emit insns after the loop if possible, as the biv final value
2841 /* If the final value is non-zero, and the giv has not been reduced,
2842 then must emit an instruction to set the final value. */
2843 if (final_value
&& !v
->new_reg
)
2845 /* Create a new register to hold the value of the giv, and then set
2846 the giv to its final value before the loop start. The giv is set
2847 to its final value before loop start to ensure that this insn
2848 will always be executed, no matter how we exit. */
2849 tem
= gen_reg_rtx (v
->mode
);
2850 emit_insn_before (gen_move_insn (tem
, v
->dest_reg
), loop_start
);
2851 emit_insn_before (gen_move_insn (v
->dest_reg
, final_value
),
2854 if (loop_dump_stream
)
2855 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2856 REGNO (v
->dest_reg
), REGNO (tem
));
2862 /* This giv is splittable. If completely unrolling the loop, save the
2863 giv's initial value. Otherwise, save the constant zero for it. */
2865 if (unroll_type
== UNROLL_COMPLETELY
)
2867 /* It is not safe to use bl->initial_value here, because it may not
2868 be invariant. It is safe to use the initial value stored in
2869 the splittable_regs array if it is set. In rare cases, it won't
2870 be set, so then we do exactly the same thing as
2871 find_splittable_regs does to get a safe value. */
2872 rtx biv_initial_value
;
2874 if (splittable_regs
[bl
->regno
])
2875 biv_initial_value
= splittable_regs
[bl
->regno
];
2876 else if (GET_CODE (bl
->initial_value
) != REG
2877 || (REGNO (bl
->initial_value
) != bl
->regno
2878 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2879 biv_initial_value
= bl
->initial_value
;
2882 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2884 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2885 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2887 biv_initial_value
= tem
;
2889 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2890 v
->add_val
, v
->mode
);
2897 /* If a giv was combined with another giv, then we can only split
2898 this giv if the giv it was combined with was reduced. This
2899 is because the value of v->new_reg is meaningless in this
2901 if (v
->same
&& ! v
->same
->new_reg
)
2903 if (loop_dump_stream
)
2904 fprintf (loop_dump_stream
,
2905 "giv combined with unreduced giv not split.\n");
2908 /* If the giv is an address destination, it could be something other
2909 than a simple register, these have to be treated differently. */
2910 else if (v
->giv_type
== DEST_REG
)
2912 /* If value is not a constant, register, or register plus
2913 constant, then compute its value into a register before
2914 loop start. This prevents invalid rtx sharing, and should
2915 generate better code. We can use bl->initial_value here
2916 instead of splittable_regs[bl->regno] because this code
2917 is going before the loop start. */
2918 if (unroll_type
== UNROLL_COMPLETELY
2919 && GET_CODE (value
) != CONST_INT
2920 && GET_CODE (value
) != REG
2921 && (GET_CODE (value
) != PLUS
2922 || GET_CODE (XEXP (value
, 0)) != REG
2923 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2925 rtx tem
= gen_reg_rtx (v
->mode
);
2926 record_base_value (REGNO (tem
), v
->add_val
, 0);
2927 emit_iv_add_mult (bl
->initial_value
, v
->mult_val
,
2928 v
->add_val
, tem
, loop
->start
);
2932 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2933 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
2937 /* Splitting address givs is useful since it will often allow us
2938 to eliminate some increment insns for the base giv as
2941 /* If the addr giv is combined with a dest_reg giv, then all
2942 references to that dest reg will be remapped, which is NOT
2943 what we want for split addr regs. We always create a new
2944 register for the split addr giv, just to be safe. */
2946 /* If we have multiple identical address givs within a
2947 single instruction, then use a single pseudo reg for
2948 both. This is necessary in case one is a match_dup
2951 v
->const_adjust
= 0;
2955 v
->dest_reg
= v
->same_insn
->dest_reg
;
2956 if (loop_dump_stream
)
2957 fprintf (loop_dump_stream
,
2958 "Sharing address givs in insn %d\n",
2959 INSN_UID (v
->insn
));
2961 /* If multiple address GIVs have been combined with the
2962 same dest_reg GIV, do not create a new register for
2964 else if (unroll_type
!= UNROLL_COMPLETELY
2965 && v
->giv_type
== DEST_ADDR
2966 && v
->same
&& v
->same
->giv_type
== DEST_ADDR
2967 && v
->same
->unrolled
2968 /* combine_givs_p may return true for some cases
2969 where the add and mult values are not equal.
2970 To share a register here, the values must be
2972 && rtx_equal_p (v
->same
->mult_val
, v
->mult_val
)
2973 && rtx_equal_p (v
->same
->add_val
, v
->add_val
)
2974 /* If the memory references have different modes,
2975 then the address may not be valid and we must
2976 not share registers. */
2977 && verify_addresses (v
, giv_inc
, unroll_number
))
2979 v
->dest_reg
= v
->same
->dest_reg
;
2982 else if (unroll_type
!= UNROLL_COMPLETELY
)
2984 /* If not completely unrolling the loop, then create a new
2985 register to hold the split value of the DEST_ADDR giv.
2986 Emit insn to initialize its value before loop start. */
2988 rtx tem
= gen_reg_rtx (v
->mode
);
2989 struct induction
*same
= v
->same
;
2990 rtx new_reg
= v
->new_reg
;
2991 record_base_value (REGNO (tem
), v
->add_val
, 0);
2993 if (same
&& same
->derived_from
)
2995 /* calculate_giv_inc doesn't work for derived givs.
2996 copy_loop_body works around the problem for the
2997 DEST_REG givs themselves, but it can't handle
2998 DEST_ADDR givs that have been combined with
2999 a derived DEST_REG giv.
3000 So Handle V as if the giv from which V->SAME has
3001 been derived has been combined with V.
3002 recombine_givs only derives givs from givs that
3003 are reduced the ordinary, so we need not worry
3004 about same->derived_from being in turn derived. */
3006 same
= same
->derived_from
;
3007 new_reg
= express_from (same
, v
);
3008 new_reg
= replace_rtx (new_reg
, same
->dest_reg
,
3012 /* If the address giv has a constant in its new_reg value,
3013 then this constant can be pulled out and put in value,
3014 instead of being part of the initialization code. */
3016 if (GET_CODE (new_reg
) == PLUS
3017 && GET_CODE (XEXP (new_reg
, 1)) == CONST_INT
)
3020 = plus_constant (tem
, INTVAL (XEXP (new_reg
, 1)));
3022 /* Only succeed if this will give valid addresses.
3023 Try to validate both the first and the last
3024 address resulting from loop unrolling, if
3025 one fails, then can't do const elim here. */
3026 if (verify_addresses (v
, giv_inc
, unroll_number
))
3028 /* Save the negative of the eliminated const, so
3029 that we can calculate the dest_reg's increment
3031 v
->const_adjust
= - INTVAL (XEXP (new_reg
, 1));
3033 new_reg
= XEXP (new_reg
, 0);
3034 if (loop_dump_stream
)
3035 fprintf (loop_dump_stream
,
3036 "Eliminating constant from giv %d\n",
3045 /* If the address hasn't been checked for validity yet, do so
3046 now, and fail completely if either the first or the last
3047 unrolled copy of the address is not a valid address
3048 for the instruction that uses it. */
3049 if (v
->dest_reg
== tem
3050 && ! verify_addresses (v
, giv_inc
, unroll_number
))
3052 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3053 if (v2
->same_insn
== v
)
3056 if (loop_dump_stream
)
3057 fprintf (loop_dump_stream
,
3058 "Invalid address for giv at insn %d\n",
3059 INSN_UID (v
->insn
));
3063 v
->new_reg
= new_reg
;
3066 /* We set this after the address check, to guarantee that
3067 the register will be initialized. */
3070 /* To initialize the new register, just move the value of
3071 new_reg into it. This is not guaranteed to give a valid
3072 instruction on machines with complex addressing modes.
3073 If we can't recognize it, then delete it and emit insns
3074 to calculate the value from scratch. */
3075 emit_insn_before (gen_rtx_SET (VOIDmode
, tem
,
3076 copy_rtx (v
->new_reg
)),
3078 if (recog_memoized (PREV_INSN (loop
->start
)) < 0)
3082 /* We can't use bl->initial_value to compute the initial
3083 value, because the loop may have been preconditioned.
3084 We must calculate it from NEW_REG. Try using
3085 force_operand instead of emit_iv_add_mult. */
3086 delete_insn (PREV_INSN (loop
->start
));
3089 ret
= force_operand (v
->new_reg
, tem
);
3091 emit_move_insn (tem
, ret
);
3092 sequence
= gen_sequence ();
3094 emit_insn_before (sequence
, loop
->start
);
3096 if (loop_dump_stream
)
3097 fprintf (loop_dump_stream
,
3098 "Invalid init insn, rewritten.\n");
3103 v
->dest_reg
= value
;
3105 /* Check the resulting address for validity, and fail
3106 if the resulting address would be invalid. */
3107 if (! verify_addresses (v
, giv_inc
, unroll_number
))
3109 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3110 if (v2
->same_insn
== v
)
3113 if (loop_dump_stream
)
3114 fprintf (loop_dump_stream
,
3115 "Invalid address for giv at insn %d\n",
3116 INSN_UID (v
->insn
));
3119 if (v
->same
&& v
->same
->derived_from
)
3121 /* Handle V as if the giv from which V->SAME has
3122 been derived has been combined with V. */
3124 v
->same
= v
->same
->derived_from
;
3125 v
->new_reg
= express_from (v
->same
, v
);
3126 v
->new_reg
= replace_rtx (v
->new_reg
, v
->same
->dest_reg
,
3132 /* Store the value of dest_reg into the insn. This sharing
3133 will not be a problem as this insn will always be copied
3136 *v
->location
= v
->dest_reg
;
3138 /* If this address giv is combined with a dest reg giv, then
3139 save the base giv's induction pointer so that we will be
3140 able to handle this address giv properly. The base giv
3141 itself does not have to be splittable. */
3143 if (v
->same
&& v
->same
->giv_type
== DEST_REG
)
3144 addr_combined_regs
[REGNO (v
->same
->new_reg
)] = v
->same
;
3146 if (GET_CODE (v
->new_reg
) == REG
)
3148 /* This giv maybe hasn't been combined with any others.
3149 Make sure that it's giv is marked as splittable here. */
3151 splittable_regs
[REGNO (v
->new_reg
)] = value
;
3152 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
3154 /* Make it appear to depend upon itself, so that the
3155 giv will be properly split in the main loop above. */
3159 addr_combined_regs
[REGNO (v
->new_reg
)] = v
;
3163 if (loop_dump_stream
)
3164 fprintf (loop_dump_stream
, "DEST_ADDR giv being split.\n");
3170 /* Currently, unreduced giv's can't be split. This is not too much
3171 of a problem since unreduced giv's are not live across loop
3172 iterations anyways. When unrolling a loop completely though,
3173 it makes sense to reduce&split givs when possible, as this will
3174 result in simpler instructions, and will not require that a reg
3175 be live across loop iterations. */
3177 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
3178 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
3179 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
3185 /* Unreduced givs are only updated once by definition. Reduced givs
3186 are updated as many times as their biv is. Mark it so if this is
3187 a splittable register. Don't need to do anything for address givs
3188 where this may not be a register. */
3190 if (GET_CODE (v
->new_reg
) == REG
)
3194 count
= reg_biv_class
[REGNO (v
->src_reg
)]->biv_count
;
3196 if (count
> 1 && v
->derived_from
)
3197 /* In this case, there is one set where the giv insn was and one
3198 set each after each biv increment. (Most are likely dead.) */
3201 splittable_regs_updates
[REGNO (v
->new_reg
)] = count
;
3206 if (loop_dump_stream
)
3210 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
3212 else if (GET_CODE (v
->dest_reg
) != REG
)
3213 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
3215 regnum
= REGNO (v
->dest_reg
);
3216 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
3217 regnum
, INSN_UID (v
->insn
));
3224 /* Try to prove that the register is dead after the loop exits. Trace every
3225 loop exit looking for an insn that will always be executed, which sets
3226 the register to some value, and appears before the first use of the register
3227 is found. If successful, then return 1, otherwise return 0. */
3229 /* ?? Could be made more intelligent in the handling of jumps, so that
3230 it can search past if statements and other similar structures. */
3233 reg_dead_after_loop (loop
, reg
)
3234 const struct loop
*loop
;
3240 int label_count
= 0;
3242 /* In addition to checking all exits of this loop, we must also check
3243 all exits of inner nested loops that would exit this loop. We don't
3244 have any way to identify those, so we just give up if there are any
3245 such inner loop exits. */
3247 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
3250 if (label_count
!= loop
->exit_count
)
3253 /* HACK: Must also search the loop fall through exit, create a label_ref
3254 here which points to the loop->end, and append the loop_number_exit_labels
3256 label
= gen_rtx_LABEL_REF (VOIDmode
, loop
->end
);
3257 LABEL_NEXTREF (label
) = loop
->exit_labels
;
3259 for ( ; label
; label
= LABEL_NEXTREF (label
))
3261 /* Succeed if find an insn which sets the biv or if reach end of
3262 function. Fail if find an insn that uses the biv, or if come to
3263 a conditional jump. */
3265 insn
= NEXT_INSN (XEXP (label
, 0));
3268 code
= GET_CODE (insn
);
3269 if (GET_RTX_CLASS (code
) == 'i')
3273 if (reg_referenced_p (reg
, PATTERN (insn
)))
3276 set
= single_set (insn
);
3277 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
3281 if (code
== JUMP_INSN
)
3283 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3285 else if (! simplejump_p (insn
)
3286 /* Prevent infinite loop following infinite loops. */
3287 || jump_count
++ > 20)
3290 insn
= JUMP_LABEL (insn
);
3293 insn
= NEXT_INSN (insn
);
3297 /* Success, the register is dead on all loop exits. */
3301 /* Try to calculate the final value of the biv, the value it will have at
3302 the end of the loop. If we can do it, return that value. */
3305 final_biv_value (loop
, bl
)
3306 const struct loop
*loop
;
3307 struct iv_class
*bl
;
3309 rtx loop_end
= loop
->end
;
3310 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3313 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3315 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3318 /* The final value for reversed bivs must be calculated differently than
3319 for ordinary bivs. In this case, there is already an insn after the
3320 loop which sets this biv's final value (if necessary), and there are
3321 no other loop exits, so we can return any value. */
3324 if (loop_dump_stream
)
3325 fprintf (loop_dump_stream
,
3326 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3331 /* Try to calculate the final value as initial value + (number of iterations
3332 * increment). For this to work, increment must be invariant, the only
3333 exit from the loop must be the fall through at the bottom (otherwise
3334 it may not have its final value when the loop exits), and the initial
3335 value of the biv must be invariant. */
3337 if (n_iterations
!= 0
3338 && ! loop
->exit_count
3339 && loop_invariant_p (loop
, bl
->initial_value
))
3341 increment
= biv_total_increment (bl
);
3343 if (increment
&& loop_invariant_p (loop
, increment
))
3345 /* Can calculate the loop exit value, emit insns after loop
3346 end to calculate this value into a temporary register in
3347 case it is needed later. */
3349 tem
= gen_reg_rtx (bl
->biv
->mode
);
3350 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3351 /* Make sure loop_end is not the last insn. */
3352 if (NEXT_INSN (loop_end
) == 0)
3353 emit_note_after (NOTE_INSN_DELETED
, loop_end
);
3354 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3355 bl
->initial_value
, tem
, NEXT_INSN (loop_end
));
3357 if (loop_dump_stream
)
3358 fprintf (loop_dump_stream
,
3359 "Final biv value for %d, calculated.\n", bl
->regno
);
3365 /* Check to see if the biv is dead at all loop exits. */
3366 if (reg_dead_after_loop (loop
, bl
->biv
->src_reg
))
3368 if (loop_dump_stream
)
3369 fprintf (loop_dump_stream
,
3370 "Final biv value for %d, biv dead after loop exit.\n",
3379 /* Try to calculate the final value of the giv, the value it will have at
3380 the end of the loop. If we can do it, return that value. */
3383 final_giv_value (loop
, v
)
3384 const struct loop
*loop
;
3385 struct induction
*v
;
3387 struct iv_class
*bl
;
3390 rtx insert_before
, seq
;
3391 rtx loop_end
= loop
->end
;
3392 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3394 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
3396 /* The final value for givs which depend on reversed bivs must be calculated
3397 differently than for ordinary givs. In this case, there is already an
3398 insn after the loop which sets this giv's final value (if necessary),
3399 and there are no other loop exits, so we can return any value. */
3402 if (loop_dump_stream
)
3403 fprintf (loop_dump_stream
,
3404 "Final giv value for %d, depends on reversed biv\n",
3405 REGNO (v
->dest_reg
));
3409 /* Try to calculate the final value as a function of the biv it depends
3410 upon. The only exit from the loop must be the fall through at the bottom
3411 (otherwise it may not have its final value when the loop exits). */
3413 /* ??? Can calculate the final giv value by subtracting off the
3414 extra biv increments times the giv's mult_val. The loop must have
3415 only one exit for this to work, but the loop iterations does not need
3418 if (n_iterations
!= 0
3419 && ! loop
->exit_count
)
3421 /* ?? It is tempting to use the biv's value here since these insns will
3422 be put after the loop, and hence the biv will have its final value
3423 then. However, this fails if the biv is subsequently eliminated.
3424 Perhaps determine whether biv's are eliminable before trying to
3425 determine whether giv's are replaceable so that we can use the
3426 biv value here if it is not eliminable. */
3428 /* We are emitting code after the end of the loop, so we must make
3429 sure that bl->initial_value is still valid then. It will still
3430 be valid if it is invariant. */
3432 increment
= biv_total_increment (bl
);
3434 if (increment
&& loop_invariant_p (loop
, increment
)
3435 && loop_invariant_p (loop
, bl
->initial_value
))
3437 /* Can calculate the loop exit value of its biv as
3438 (n_iterations * increment) + initial_value */
3440 /* The loop exit value of the giv is then
3441 (final_biv_value - extra increments) * mult_val + add_val.
3442 The extra increments are any increments to the biv which
3443 occur in the loop after the giv's value is calculated.
3444 We must search from the insn that sets the giv to the end
3445 of the loop to calculate this value. */
3447 insert_before
= NEXT_INSN (loop_end
);
3449 /* Put the final biv value in tem. */
3450 tem
= gen_reg_rtx (bl
->biv
->mode
);
3451 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3452 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3453 bl
->initial_value
, tem
, insert_before
);
3455 /* Subtract off extra increments as we find them. */
3456 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3457 insn
= NEXT_INSN (insn
))
3459 struct induction
*biv
;
3461 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3462 if (biv
->insn
== insn
)
3465 tem
= expand_binop (GET_MODE (tem
), sub_optab
, tem
,
3466 biv
->add_val
, NULL_RTX
, 0,
3468 seq
= gen_sequence ();
3470 emit_insn_before (seq
, insert_before
);
3474 /* Now calculate the giv's final value. */
3475 emit_iv_add_mult (tem
, v
->mult_val
, v
->add_val
, tem
,
3478 if (loop_dump_stream
)
3479 fprintf (loop_dump_stream
,
3480 "Final giv value for %d, calc from biv's value.\n",
3481 REGNO (v
->dest_reg
));
3487 /* Replaceable giv's should never reach here. */
3491 /* Check to see if the biv is dead at all loop exits. */
3492 if (reg_dead_after_loop (loop
, v
->dest_reg
))
3494 if (loop_dump_stream
)
3495 fprintf (loop_dump_stream
,
3496 "Final giv value for %d, giv dead after loop exit.\n",
3497 REGNO (v
->dest_reg
));
3506 /* Look back before LOOP->START for then insn that sets REG and return
3507 the equivalent constant if there is a REG_EQUAL note otherwise just
3508 the SET_SRC of REG. */
3511 loop_find_equiv_value (loop
, reg
)
3512 const struct loop
*loop
;
3515 rtx loop_start
= loop
->start
;
3520 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3522 if (GET_CODE (insn
) == CODE_LABEL
)
3525 else if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i'
3526 && reg_set_p (reg
, insn
))
3528 /* We found the last insn before the loop that sets the register.
3529 If it sets the entire register, and has a REG_EQUAL note,
3530 then use the value of the REG_EQUAL note. */
3531 if ((set
= single_set (insn
))
3532 && (SET_DEST (set
) == reg
))
3534 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3536 /* Only use the REG_EQUAL note if it is a constant.
3537 Other things, divide in particular, will cause
3538 problems later if we use them. */
3539 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3540 && CONSTANT_P (XEXP (note
, 0)))
3541 ret
= XEXP (note
, 0);
3543 ret
= SET_SRC (set
);
3551 /* Return a simplified rtx for the expression OP - REG.
3553 REG must appear in OP, and OP must be a register or the sum of a register
3556 Thus, the return value must be const0_rtx or the second term.
3558 The caller is responsible for verifying that REG appears in OP and OP has
3562 subtract_reg_term (op
, reg
)
3567 if (GET_CODE (op
) == PLUS
)
3569 if (XEXP (op
, 0) == reg
)
3570 return XEXP (op
, 1);
3571 else if (XEXP (op
, 1) == reg
)
3572 return XEXP (op
, 0);
3574 /* OP does not contain REG as a term. */
3579 /* Find and return register term common to both expressions OP0 and
3580 OP1 or NULL_RTX if no such term exists. Each expression must be a
3581 REG or a PLUS of a REG. */
3584 find_common_reg_term (op0
, op1
)
3587 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3588 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3595 if (GET_CODE (op0
) == PLUS
)
3596 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3598 op01
= const0_rtx
, op00
= op0
;
3600 if (GET_CODE (op1
) == PLUS
)
3601 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3603 op11
= const0_rtx
, op10
= op1
;
3605 /* Find and return common register term if present. */
3606 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3608 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3612 /* No common register term found. */
3616 /* Calculate the number of loop iterations. Returns the exact number of loop
3617 iterations if it can be calculated, otherwise returns zero. */
3619 unsigned HOST_WIDE_INT
3620 loop_iterations (loop
)
3623 rtx comparison
, comparison_value
;
3624 rtx iteration_var
, initial_value
, increment
, final_value
;
3625 enum rtx_code comparison_code
;
3626 HOST_WIDE_INT abs_inc
;
3627 unsigned HOST_WIDE_INT abs_diff
;
3630 int unsigned_p
, compare_dir
, final_larger
;
3633 struct loop_info
*loop_info
= LOOP_INFO (loop
);
3635 loop_info
->n_iterations
= 0;
3636 loop_info
->initial_value
= 0;
3637 loop_info
->initial_equiv_value
= 0;
3638 loop_info
->comparison_value
= 0;
3639 loop_info
->final_value
= 0;
3640 loop_info
->final_equiv_value
= 0;
3641 loop_info
->increment
= 0;
3642 loop_info
->iteration_var
= 0;
3643 loop_info
->unroll_number
= 1;
3645 /* We used to use prev_nonnote_insn here, but that fails because it might
3646 accidentally get the branch for a contained loop if the branch for this
3647 loop was deleted. We can only trust branches immediately before the
3649 last_loop_insn
= PREV_INSN (loop
->end
);
3651 /* ??? We should probably try harder to find the jump insn
3652 at the end of the loop. The following code assumes that
3653 the last loop insn is a jump to the top of the loop. */
3654 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3656 if (loop_dump_stream
)
3657 fprintf (loop_dump_stream
,
3658 "Loop iterations: No final conditional branch found.\n");
3662 /* If there is a more than a single jump to the top of the loop
3663 we cannot (easily) determine the iteration count. */
3664 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3666 if (loop_dump_stream
)
3667 fprintf (loop_dump_stream
,
3668 "Loop iterations: Loop has multiple back edges.\n");
3672 /* Find the iteration variable. If the last insn is a conditional
3673 branch, and the insn before tests a register value, make that the
3674 iteration variable. */
3676 comparison
= get_condition_for_loop (loop
, last_loop_insn
);
3677 if (comparison
== 0)
3679 if (loop_dump_stream
)
3680 fprintf (loop_dump_stream
,
3681 "Loop iterations: No final comparison found.\n");
3685 /* ??? Get_condition may switch position of induction variable and
3686 invariant register when it canonicalizes the comparison. */
3688 comparison_code
= GET_CODE (comparison
);
3689 iteration_var
= XEXP (comparison
, 0);
3690 comparison_value
= XEXP (comparison
, 1);
3692 if (GET_CODE (iteration_var
) != REG
)
3694 if (loop_dump_stream
)
3695 fprintf (loop_dump_stream
,
3696 "Loop iterations: Comparison not against register.\n");
3700 /* The only new registers that are created before loop iterations
3701 are givs made from biv increments or registers created by
3702 load_mems. In the latter case, it is possible that try_copy_prop
3703 will propagate a new pseudo into the old iteration register but
3704 this will be marked by having the REG_USERVAR_P bit set. */
3706 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
3707 && ! REG_USERVAR_P (iteration_var
))
3710 iteration_info (loop
, iteration_var
, &initial_value
, &increment
);
3712 if (initial_value
== 0)
3713 /* iteration_info already printed a message. */
3718 switch (comparison_code
)
3733 /* Cannot determine loop iterations with this case. */
3752 /* If the comparison value is an invariant register, then try to find
3753 its value from the insns before the start of the loop. */
3755 final_value
= comparison_value
;
3756 if (GET_CODE (comparison_value
) == REG
3757 && loop_invariant_p (loop
, comparison_value
))
3759 final_value
= loop_find_equiv_value (loop
, comparison_value
);
3761 /* If we don't get an invariant final value, we are better
3762 off with the original register. */
3763 if (! loop_invariant_p (loop
, final_value
))
3764 final_value
= comparison_value
;
3767 /* Calculate the approximate final value of the induction variable
3768 (on the last successful iteration). The exact final value
3769 depends on the branch operator, and increment sign. It will be
3770 wrong if the iteration variable is not incremented by one each
3771 time through the loop and (comparison_value + off_by_one -
3772 initial_value) % increment != 0.
3773 ??? Note that the final_value may overflow and thus final_larger
3774 will be bogus. A potentially infinite loop will be classified
3775 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3777 final_value
= plus_constant (final_value
, off_by_one
);
3779 /* Save the calculated values describing this loop's bounds, in case
3780 precondition_loop_p will need them later. These values can not be
3781 recalculated inside precondition_loop_p because strength reduction
3782 optimizations may obscure the loop's structure.
3784 These values are only required by precondition_loop_p and insert_bct
3785 whenever the number of iterations cannot be computed at compile time.
3786 Only the difference between final_value and initial_value is
3787 important. Note that final_value is only approximate. */
3788 loop_info
->initial_value
= initial_value
;
3789 loop_info
->comparison_value
= comparison_value
;
3790 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3791 loop_info
->increment
= increment
;
3792 loop_info
->iteration_var
= iteration_var
;
3793 loop_info
->comparison_code
= comparison_code
;
3795 /* Try to determine the iteration count for loops such
3796 as (for i = init; i < init + const; i++). When running the
3797 loop optimization twice, the first pass often converts simple
3798 loops into this form. */
3800 if (REG_P (initial_value
))
3806 reg1
= initial_value
;
3807 if (GET_CODE (final_value
) == PLUS
)
3808 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3810 reg2
= final_value
, const2
= const0_rtx
;
3812 /* Check for initial_value = reg1, final_value = reg2 + const2,
3813 where reg1 != reg2. */
3814 if (REG_P (reg2
) && reg2
!= reg1
)
3818 /* Find what reg1 is equivalent to. Hopefully it will
3819 either be reg2 or reg2 plus a constant. */
3820 temp
= loop_find_equiv_value (loop
, reg1
);
3822 if (find_common_reg_term (temp
, reg2
))
3823 initial_value
= temp
;
3826 /* Find what reg2 is equivalent to. Hopefully it will
3827 either be reg1 or reg1 plus a constant. Let's ignore
3828 the latter case for now since it is not so common. */
3829 temp
= loop_find_equiv_value (loop
, reg2
);
3831 if (temp
== loop_info
->iteration_var
)
3832 temp
= initial_value
;
3834 final_value
= (const2
== const0_rtx
)
3835 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3838 else if (loop
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3842 /* When running the loop optimizer twice, check_dbra_loop
3843 further obfuscates reversible loops of the form:
3844 for (i = init; i < init + const; i++). We often end up with
3845 final_value = 0, initial_value = temp, temp = temp2 - init,
3846 where temp2 = init + const. If the loop has a vtop we
3847 can replace initial_value with const. */
3849 temp
= loop_find_equiv_value (loop
, reg1
);
3851 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3853 rtx temp2
= loop_find_equiv_value (loop
, XEXP (temp
, 0));
3855 if (GET_CODE (temp2
) == PLUS
3856 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3857 initial_value
= XEXP (temp2
, 1);
3862 /* If have initial_value = reg + const1 and final_value = reg +
3863 const2, then replace initial_value with const1 and final_value
3864 with const2. This should be safe since we are protected by the
3865 initial comparison before entering the loop if we have a vtop.
3866 For example, a + b < a + c is not equivalent to b < c for all a
3867 when using modulo arithmetic.
3869 ??? Without a vtop we could still perform the optimization if we check
3870 the initial and final values carefully. */
3872 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3874 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3875 final_value
= subtract_reg_term (final_value
, reg_term
);
3878 loop_info
->initial_equiv_value
= initial_value
;
3879 loop_info
->final_equiv_value
= final_value
;
3881 /* For EQ comparison loops, we don't have a valid final value.
3882 Check this now so that we won't leave an invalid value if we
3883 return early for any other reason. */
3884 if (comparison_code
== EQ
)
3885 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3889 if (loop_dump_stream
)
3890 fprintf (loop_dump_stream
,
3891 "Loop iterations: Increment value can't be calculated.\n");
3895 if (GET_CODE (increment
) != CONST_INT
)
3897 /* If we have a REG, check to see if REG holds a constant value. */
3898 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3899 clear if it is worthwhile to try to handle such RTL. */
3900 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3901 increment
= loop_find_equiv_value (loop
, increment
);
3903 if (GET_CODE (increment
) != CONST_INT
)
3905 if (loop_dump_stream
)
3907 fprintf (loop_dump_stream
,
3908 "Loop iterations: Increment value not constant ");
3909 print_rtl (loop_dump_stream
, increment
);
3910 fprintf (loop_dump_stream
, ".\n");
3914 loop_info
->increment
= increment
;
3917 if (GET_CODE (initial_value
) != CONST_INT
)
3919 if (loop_dump_stream
)
3921 fprintf (loop_dump_stream
,
3922 "Loop iterations: Initial value not constant ");
3923 print_rtl (loop_dump_stream
, initial_value
);
3924 fprintf (loop_dump_stream
, ".\n");
3928 else if (comparison_code
== EQ
)
3930 if (loop_dump_stream
)
3931 fprintf (loop_dump_stream
,
3932 "Loop iterations: EQ comparison loop.\n");
3935 else if (GET_CODE (final_value
) != CONST_INT
)
3937 if (loop_dump_stream
)
3939 fprintf (loop_dump_stream
,
3940 "Loop iterations: Final value not constant ");
3941 print_rtl (loop_dump_stream
, final_value
);
3942 fprintf (loop_dump_stream
, ".\n");
3947 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3950 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3951 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3952 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3953 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3955 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3956 - (INTVAL (final_value
) < INTVAL (initial_value
));
3958 if (INTVAL (increment
) > 0)
3960 else if (INTVAL (increment
) == 0)
3965 /* There are 27 different cases: compare_dir = -1, 0, 1;
3966 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3967 There are 4 normal cases, 4 reverse cases (where the iteration variable
3968 will overflow before the loop exits), 4 infinite loop cases, and 15
3969 immediate exit (0 or 1 iteration depending on loop type) cases.
3970 Only try to optimize the normal cases. */
3972 /* (compare_dir/final_larger/increment_dir)
3973 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3974 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3975 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3976 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3978 /* ?? If the meaning of reverse loops (where the iteration variable
3979 will overflow before the loop exits) is undefined, then could
3980 eliminate all of these special checks, and just always assume
3981 the loops are normal/immediate/infinite. Note that this means
3982 the sign of increment_dir does not have to be known. Also,
3983 since it does not really hurt if immediate exit loops or infinite loops
3984 are optimized, then that case could be ignored also, and hence all
3985 loops can be optimized.
3987 According to ANSI Spec, the reverse loop case result is undefined,
3988 because the action on overflow is undefined.
3990 See also the special test for NE loops below. */
3992 if (final_larger
== increment_dir
&& final_larger
!= 0
3993 && (final_larger
== compare_dir
|| compare_dir
== 0))
3998 if (loop_dump_stream
)
3999 fprintf (loop_dump_stream
,
4000 "Loop iterations: Not normal loop.\n");
4004 /* Calculate the number of iterations, final_value is only an approximation,
4005 so correct for that. Note that abs_diff and n_iterations are
4006 unsigned, because they can be as large as 2^n - 1. */
4008 abs_inc
= INTVAL (increment
);
4010 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
4011 else if (abs_inc
< 0)
4013 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
4019 /* For NE tests, make sure that the iteration variable won't miss
4020 the final value. If abs_diff mod abs_incr is not zero, then the
4021 iteration variable will overflow before the loop exits, and we
4022 can not calculate the number of iterations. */
4023 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
4026 /* Note that the number of iterations could be calculated using
4027 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4028 handle potential overflow of the summation. */
4029 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
4030 return loop_info
->n_iterations
;
4034 /* Replace uses of split bivs with their split pseudo register. This is
4035 for original instructions which remain after loop unrolling without
4039 remap_split_bivs (x
)
4042 register enum rtx_code code
;
4044 register const char *fmt
;
4049 code
= GET_CODE (x
);
4064 /* If non-reduced/final-value givs were split, then this would also
4065 have to remap those givs also. */
4067 if (REGNO (x
) < max_reg_before_loop
4068 && REG_IV_TYPE (REGNO (x
)) == BASIC_INDUCT
)
4069 return reg_biv_class
[REGNO (x
)]->biv
->src_reg
;
4076 fmt
= GET_RTX_FORMAT (code
);
4077 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4080 XEXP (x
, i
) = remap_split_bivs (XEXP (x
, i
));
4081 else if (fmt
[i
] == 'E')
4084 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4085 XVECEXP (x
, i
, j
) = remap_split_bivs (XVECEXP (x
, i
, j
));
4091 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4092 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4093 return 0. COPY_START is where we can start looking for the insns
4094 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4097 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4098 must dominate LAST_UID.
4100 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4101 may not dominate LAST_UID.
4103 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4104 must dominate LAST_UID. */
4107 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
4114 int passed_jump
= 0;
4115 rtx p
= NEXT_INSN (copy_start
);
4117 while (INSN_UID (p
) != first_uid
)
4119 if (GET_CODE (p
) == JUMP_INSN
)
4121 /* Could not find FIRST_UID. */
4127 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4128 if (GET_RTX_CLASS (GET_CODE (p
)) != 'i'
4129 || ! dead_or_set_regno_p (p
, regno
))
4132 /* FIRST_UID is always executed. */
4133 if (passed_jump
== 0)
4136 while (INSN_UID (p
) != last_uid
)
4138 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4139 can not be sure that FIRST_UID dominates LAST_UID. */
4140 if (GET_CODE (p
) == CODE_LABEL
)
4142 /* Could not find LAST_UID, but we reached the end of the loop, so
4144 else if (p
== copy_end
)
4149 /* FIRST_UID is always executed if LAST_UID is executed. */