1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001, 2002
3 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
138 #include "insn-config.h"
139 #include "integrate.h"
143 #include "function.h"
147 #include "hard-reg-set.h"
148 #include "basic-block.h"
152 /* The prime factors looked for when trying to unroll a loop by some
153 number which is modulo the total number of iterations. Just checking
154 for these 4 prime factors will find at least one factor for 75% of
155 all numbers theoretically. Practically speaking, this will succeed
156 almost all of the time since loops are generally a multiple of 2
159 #define NUM_FACTORS 4
161 static struct _factor
{ const int factor
; int count
; }
162 factors
[NUM_FACTORS
] = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
164 /* Describes the different types of loop unrolling performed. */
173 /* Indexed by register number, if nonzero, then it contains a pointer
174 to a struct induction for a DEST_REG giv which has been combined with
175 one of more address givs. This is needed because whenever such a DEST_REG
176 giv is modified, we must modify the value of all split address givs
177 that were combined with this DEST_REG giv. */
179 static struct induction
**addr_combined_regs
;
181 /* Indexed by register number, if this is a splittable induction variable,
182 then this will hold the current value of the register, which depends on the
185 static rtx
*splittable_regs
;
187 /* Indexed by register number, if this is a splittable induction variable,
188 then this will hold the number of instructions in the loop that modify
189 the induction variable. Used to ensure that only the last insn modifying
190 a split iv will update the original iv of the dest. */
192 static int *splittable_regs_updates
;
194 /* Forward declarations. */
196 static rtx simplify_cmp_and_jump_insns
PARAMS ((enum rtx_code
,
199 static void init_reg_map
PARAMS ((struct inline_remap
*, int));
200 static rtx calculate_giv_inc
PARAMS ((rtx
, rtx
, unsigned int));
201 static rtx initial_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
202 static void final_reg_note_copy
PARAMS ((rtx
*, struct inline_remap
*));
203 static void copy_loop_body
PARAMS ((struct loop
*, rtx
, rtx
,
204 struct inline_remap
*, rtx
, int,
205 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
206 static int find_splittable_regs
PARAMS ((const struct loop
*,
207 enum unroll_types
, int));
208 static int find_splittable_givs
PARAMS ((const struct loop
*,
209 struct iv_class
*, enum unroll_types
,
211 static int reg_dead_after_loop
PARAMS ((const struct loop
*, rtx
));
212 static rtx fold_rtx_mult_add
PARAMS ((rtx
, rtx
, rtx
, enum machine_mode
));
213 static rtx remap_split_bivs
PARAMS ((struct loop
*, rtx
));
214 static rtx find_common_reg_term
PARAMS ((rtx
, rtx
));
215 static rtx subtract_reg_term
PARAMS ((rtx
, rtx
));
216 static rtx loop_find_equiv_value
PARAMS ((const struct loop
*, rtx
));
217 static rtx ujump_to_loop_cont
PARAMS ((rtx
, rtx
));
219 /* Try to unroll one loop and split induction variables in the loop.
221 The loop is described by the arguments LOOP and INSN_COUNT.
222 STRENGTH_REDUCTION_P indicates whether information generated in the
223 strength reduction pass is available.
225 This function is intended to be called from within `strength_reduce'
229 unroll_loop (loop
, insn_count
, strength_reduce_p
)
232 int strength_reduce_p
;
234 struct loop_info
*loop_info
= LOOP_INFO (loop
);
235 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
238 unsigned HOST_WIDE_INT temp
;
239 int unroll_number
= 1;
240 rtx copy_start
, copy_end
;
241 rtx insn
, sequence
, pattern
, tem
;
242 int max_labelno
, max_insnno
;
244 struct inline_remap
*map
;
245 char *local_label
= NULL
;
247 unsigned int max_local_regnum
;
248 unsigned int maxregnum
;
252 int splitting_not_safe
= 0;
253 enum unroll_types unroll_type
= UNROLL_NAIVE
;
254 int loop_preconditioned
= 0;
256 /* This points to the last real insn in the loop, which should be either
257 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
260 rtx loop_start
= loop
->start
;
261 rtx loop_end
= loop
->end
;
263 /* Don't bother unrolling huge loops. Since the minimum factor is
264 two, loops greater than one half of MAX_UNROLLED_INSNS will never
266 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
268 if (loop_dump_stream
)
269 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
273 /* Determine type of unroll to perform. Depends on the number of iterations
274 and the size of the loop. */
276 /* If there is no strength reduce info, then set
277 loop_info->n_iterations to zero. This can happen if
278 strength_reduce can't find any bivs in the loop. A value of zero
279 indicates that the number of iterations could not be calculated. */
281 if (! strength_reduce_p
)
282 loop_info
->n_iterations
= 0;
284 if (loop_dump_stream
&& loop_info
->n_iterations
> 0)
286 fputs ("Loop unrolling: ", loop_dump_stream
);
287 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
288 loop_info
->n_iterations
);
289 fputs (" iterations.\n", loop_dump_stream
);
292 /* Find and save a pointer to the last nonnote insn in the loop. */
294 last_loop_insn
= prev_nonnote_insn (loop_end
);
296 /* Calculate how many times to unroll the loop. Indicate whether or
297 not the loop is being completely unrolled. */
299 if (loop_info
->n_iterations
== 1)
301 /* Handle the case where the loop begins with an unconditional
302 jump to the loop condition. Make sure to delete the jump
303 insn, otherwise the loop body will never execute. */
305 rtx ujump
= ujump_to_loop_cont (loop
->start
, loop
->cont
);
307 delete_related_insns (ujump
);
309 /* If number of iterations is exactly 1, then eliminate the compare and
310 branch at the end of the loop since they will never be taken.
311 Then return, since no other action is needed here. */
313 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
314 don't do anything. */
316 if (GET_CODE (last_loop_insn
) == BARRIER
)
318 /* Delete the jump insn. This will delete the barrier also. */
319 delete_related_insns (PREV_INSN (last_loop_insn
));
321 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
324 rtx prev
= PREV_INSN (last_loop_insn
);
326 delete_related_insns (last_loop_insn
);
328 /* The immediately preceding insn may be a compare which must be
330 if (only_sets_cc0_p (prev
))
331 delete_related_insns (prev
);
335 /* Remove the loop notes since this is no longer a loop. */
337 delete_related_insns (loop
->vtop
);
339 delete_related_insns (loop
->cont
);
341 delete_related_insns (loop_start
);
343 delete_related_insns (loop_end
);
347 else if (loop_info
->n_iterations
> 0
348 /* Avoid overflow in the next expression. */
349 && loop_info
->n_iterations
< (unsigned) MAX_UNROLLED_INSNS
350 && loop_info
->n_iterations
* insn_count
< (unsigned) MAX_UNROLLED_INSNS
)
352 unroll_number
= loop_info
->n_iterations
;
353 unroll_type
= UNROLL_COMPLETELY
;
355 else if (loop_info
->n_iterations
> 0)
357 /* Try to factor the number of iterations. Don't bother with the
358 general case, only using 2, 3, 5, and 7 will get 75% of all
359 numbers theoretically, and almost all in practice. */
361 for (i
= 0; i
< NUM_FACTORS
; i
++)
362 factors
[i
].count
= 0;
364 temp
= loop_info
->n_iterations
;
365 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
366 while (temp
% factors
[i
].factor
== 0)
369 temp
= temp
/ factors
[i
].factor
;
372 /* Start with the larger factors first so that we generally
373 get lots of unrolling. */
377 for (i
= 3; i
>= 0; i
--)
378 while (factors
[i
].count
--)
380 if (temp
* factors
[i
].factor
< (unsigned) MAX_UNROLLED_INSNS
)
382 unroll_number
*= factors
[i
].factor
;
383 temp
*= factors
[i
].factor
;
389 /* If we couldn't find any factors, then unroll as in the normal
391 if (unroll_number
== 1)
393 if (loop_dump_stream
)
394 fprintf (loop_dump_stream
, "Loop unrolling: No factors found.\n");
397 unroll_type
= UNROLL_MODULO
;
400 /* Default case, calculate number of times to unroll loop based on its
402 if (unroll_type
== UNROLL_NAIVE
)
404 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
406 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
412 /* Now we know how many times to unroll the loop. */
414 if (loop_dump_stream
)
415 fprintf (loop_dump_stream
, "Unrolling loop %d times.\n", unroll_number
);
417 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
419 /* Loops of these types can start with jump down to the exit condition
420 in rare circumstances.
422 Consider a pair of nested loops where the inner loop is part
423 of the exit code for the outer loop.
425 In this case jump.c will not duplicate the exit test for the outer
426 loop, so it will start with a jump to the exit code.
428 Then consider if the inner loop turns out to iterate once and
429 only once. We will end up deleting the jumps associated with
430 the inner loop. However, the loop notes are not removed from
431 the instruction stream.
433 And finally assume that we can compute the number of iterations
436 In this case unroll may want to unroll the outer loop even though
437 it starts with a jump to the outer loop's exit code.
439 We could try to optimize this case, but it hardly seems worth it.
440 Just return without unrolling the loop in such cases. */
443 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
444 insn
= NEXT_INSN (insn
);
445 if (GET_CODE (insn
) == JUMP_INSN
)
449 if (unroll_type
== UNROLL_COMPLETELY
)
451 /* Completely unrolling the loop: Delete the compare and branch at
452 the end (the last two instructions). This delete must done at the
453 very end of loop unrolling, to avoid problems with calls to
454 back_branch_in_range_p, which is called by find_splittable_regs.
455 All increments of splittable bivs/givs are changed to load constant
458 copy_start
= loop_start
;
460 /* Set insert_before to the instruction immediately after the JUMP_INSN
461 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
462 the loop will be correctly handled by copy_loop_body. */
463 insert_before
= NEXT_INSN (last_loop_insn
);
465 /* Set copy_end to the insn before the jump at the end of the loop. */
466 if (GET_CODE (last_loop_insn
) == BARRIER
)
467 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
468 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
470 copy_end
= PREV_INSN (last_loop_insn
);
472 /* The instruction immediately before the JUMP_INSN may be a compare
473 instruction which we do not want to copy. */
474 if (sets_cc0_p (PREV_INSN (copy_end
)))
475 copy_end
= PREV_INSN (copy_end
);
480 /* We currently can't unroll a loop if it doesn't end with a
481 JUMP_INSN. There would need to be a mechanism that recognizes
482 this case, and then inserts a jump after each loop body, which
483 jumps to after the last loop body. */
484 if (loop_dump_stream
)
485 fprintf (loop_dump_stream
,
486 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
490 else if (unroll_type
== UNROLL_MODULO
)
492 /* Partially unrolling the loop: The compare and branch at the end
493 (the last two instructions) must remain. Don't copy the compare
494 and branch instructions at the end of the loop. Insert the unrolled
495 code immediately before the compare/branch at the end so that the
496 code will fall through to them as before. */
498 copy_start
= loop_start
;
500 /* Set insert_before to the jump insn at the end of the loop.
501 Set copy_end to before the jump insn at the end of the loop. */
502 if (GET_CODE (last_loop_insn
) == BARRIER
)
504 insert_before
= PREV_INSN (last_loop_insn
);
505 copy_end
= PREV_INSN (insert_before
);
507 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
509 insert_before
= last_loop_insn
;
511 /* The instruction immediately before the JUMP_INSN may be a compare
512 instruction which we do not want to copy or delete. */
513 if (sets_cc0_p (PREV_INSN (insert_before
)))
514 insert_before
= PREV_INSN (insert_before
);
516 copy_end
= PREV_INSN (insert_before
);
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");
532 /* Normal case: Must copy the compare and branch instructions at the
535 if (GET_CODE (last_loop_insn
) == BARRIER
)
537 /* Loop ends with an unconditional jump and a barrier.
538 Handle this like above, don't copy jump and barrier.
539 This is not strictly necessary, but doing so prevents generating
540 unconditional jumps to an immediately following label.
542 This will be corrected below if the target of this jump is
543 not the start_label. */
545 insert_before
= PREV_INSN (last_loop_insn
);
546 copy_end
= PREV_INSN (insert_before
);
548 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
550 /* Set insert_before to immediately after the JUMP_INSN, so that
551 NOTEs at the end of the loop will be correctly handled by
553 insert_before
= NEXT_INSN (last_loop_insn
);
554 copy_end
= last_loop_insn
;
558 /* We currently can't unroll a loop if it doesn't end with a
559 JUMP_INSN. There would need to be a mechanism that recognizes
560 this case, and then inserts a jump after each loop body, which
561 jumps to after the last loop body. */
562 if (loop_dump_stream
)
563 fprintf (loop_dump_stream
,
564 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
568 /* If copying exit test branches because they can not be eliminated,
569 then must convert the fall through case of the branch to a jump past
570 the end of the loop. Create a label to emit after the loop and save
571 it for later use. Do not use the label after the loop, if any, since
572 it might be used by insns outside the loop, or there might be insns
573 added before it later by final_[bg]iv_value which must be after
574 the real exit label. */
575 exit_label
= gen_label_rtx ();
578 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
579 insn
= NEXT_INSN (insn
);
581 if (GET_CODE (insn
) == JUMP_INSN
)
583 /* The loop starts with a jump down to the exit condition test.
584 Start copying the loop after the barrier following this
586 copy_start
= NEXT_INSN (insn
);
588 /* Splitting induction variables doesn't work when the loop is
589 entered via a jump to the bottom, because then we end up doing
590 a comparison against a new register for a split variable, but
591 we did not execute the set insn for the new register because
592 it was skipped over. */
593 splitting_not_safe
= 1;
594 if (loop_dump_stream
)
595 fprintf (loop_dump_stream
,
596 "Splitting not safe, because loop not entered at top.\n");
599 copy_start
= loop_start
;
602 /* This should always be the first label in the loop. */
603 start_label
= NEXT_INSN (copy_start
);
604 /* There may be a line number note and/or a loop continue note here. */
605 while (GET_CODE (start_label
) == NOTE
)
606 start_label
= NEXT_INSN (start_label
);
607 if (GET_CODE (start_label
) != CODE_LABEL
)
609 /* This can happen as a result of jump threading. If the first insns in
610 the loop test the same condition as the loop's backward jump, or the
611 opposite condition, then the backward jump will be modified to point
612 to elsewhere, and the loop's start label is deleted.
614 This case currently can not be handled by the loop unrolling code. */
616 if (loop_dump_stream
)
617 fprintf (loop_dump_stream
,
618 "Unrolling failure: unknown insns between BEG note and loop label.\n");
621 if (LABEL_NAME (start_label
))
623 /* The jump optimization pass must have combined the original start label
624 with a named label for a goto. We can't unroll this case because
625 jumps which go to the named label must be handled differently than
626 jumps to the loop start, and it is impossible to differentiate them
628 if (loop_dump_stream
)
629 fprintf (loop_dump_stream
,
630 "Unrolling failure: loop start label is gone\n");
634 if (unroll_type
== UNROLL_NAIVE
635 && GET_CODE (last_loop_insn
) == BARRIER
636 && GET_CODE (PREV_INSN (last_loop_insn
)) == JUMP_INSN
637 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
639 /* In this case, we must copy the jump and barrier, because they will
640 not be converted to jumps to an immediately following label. */
642 insert_before
= NEXT_INSN (last_loop_insn
);
643 copy_end
= last_loop_insn
;
646 if (unroll_type
== UNROLL_NAIVE
647 && GET_CODE (last_loop_insn
) == JUMP_INSN
648 && start_label
!= JUMP_LABEL (last_loop_insn
))
650 /* ??? The loop ends with a conditional branch that does not branch back
651 to the loop start label. In this case, we must emit an unconditional
652 branch to the loop exit after emitting the final branch.
653 copy_loop_body does not have support for this currently, so we
654 give up. It doesn't seem worthwhile to unroll anyways since
655 unrolling would increase the number of branch instructions
657 if (loop_dump_stream
)
658 fprintf (loop_dump_stream
,
659 "Unrolling failure: final conditional branch not to loop start\n");
663 /* Allocate a translation table for the labels and insn numbers.
664 They will be filled in as we copy the insns in the loop. */
666 max_labelno
= max_label_num ();
667 max_insnno
= get_max_uid ();
669 /* Various paths through the unroll code may reach the "egress" label
670 without initializing fields within the map structure.
672 To be safe, we use xcalloc to zero the memory. */
673 map
= (struct inline_remap
*) xcalloc (1, sizeof (struct inline_remap
));
675 /* Allocate the label map. */
679 map
->label_map
= (rtx
*) xcalloc (max_labelno
, sizeof (rtx
));
680 local_label
= (char *) xcalloc (max_labelno
, sizeof (char));
683 /* Search the loop and mark all local labels, i.e. the ones which have to
684 be distinct labels when copied. For all labels which might be
685 non-local, set their label_map entries to point to themselves.
686 If they happen to be local their label_map entries will be overwritten
687 before the loop body is copied. The label_map entries for local labels
688 will be set to a different value each time the loop body is copied. */
690 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
694 if (GET_CODE (insn
) == CODE_LABEL
)
695 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
696 else if (GET_CODE (insn
) == JUMP_INSN
)
698 if (JUMP_LABEL (insn
))
699 set_label_in_map (map
,
700 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)),
702 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
703 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
705 rtx pat
= PATTERN (insn
);
706 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
707 int len
= XVECLEN (pat
, diff_vec_p
);
710 for (i
= 0; i
< len
; i
++)
712 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
713 set_label_in_map (map
, CODE_LABEL_NUMBER (label
), label
);
717 if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)))
718 set_label_in_map (map
, CODE_LABEL_NUMBER (XEXP (note
, 0)),
722 /* Allocate space for the insn map. */
724 map
->insn_map
= (rtx
*) xmalloc (max_insnno
* sizeof (rtx
));
726 /* Set this to zero, to indicate that we are doing loop unrolling,
727 not function inlining. */
728 map
->inline_target
= 0;
730 /* The register and constant maps depend on the number of registers
731 present, so the final maps can't be created until after
732 find_splittable_regs is called. However, they are needed for
733 preconditioning, so we create temporary maps when preconditioning
736 /* The preconditioning code may allocate two new pseudo registers. */
737 maxregnum
= max_reg_num ();
739 /* local_regno is only valid for regnos < max_local_regnum. */
740 max_local_regnum
= maxregnum
;
742 /* Allocate and zero out the splittable_regs and addr_combined_regs
743 arrays. These must be zeroed here because they will be used if
744 loop preconditioning is performed, and must be zero for that case.
746 It is safe to do this here, since the extra registers created by the
747 preconditioning code and find_splittable_regs will never be used
748 to access the splittable_regs[] and addr_combined_regs[] arrays. */
750 splittable_regs
= (rtx
*) xcalloc (maxregnum
, sizeof (rtx
));
751 splittable_regs_updates
= (int *) xcalloc (maxregnum
, sizeof (int));
753 = (struct induction
**) xcalloc (maxregnum
, sizeof (struct induction
*));
754 local_regno
= (char *) xcalloc (maxregnum
, sizeof (char));
756 /* Mark all local registers, i.e. the ones which are referenced only
758 if (INSN_UID (copy_end
) < max_uid_for_loop
)
760 int copy_start_luid
= INSN_LUID (copy_start
);
761 int copy_end_luid
= INSN_LUID (copy_end
);
763 /* If a register is used in the jump insn, we must not duplicate it
764 since it will also be used outside the loop. */
765 if (GET_CODE (copy_end
) == JUMP_INSN
)
768 /* If we have a target that uses cc0, then we also must not duplicate
769 the insn that sets cc0 before the jump insn, if one is present. */
771 if (GET_CODE (copy_end
) == JUMP_INSN
772 && sets_cc0_p (PREV_INSN (copy_end
)))
776 /* If copy_start points to the NOTE that starts the loop, then we must
777 use the next luid, because invariant pseudo-regs moved out of the loop
778 have their lifetimes modified to start here, but they are not safe
780 if (copy_start
== loop_start
)
783 /* If a pseudo's lifetime is entirely contained within this loop, then we
784 can use a different pseudo in each unrolled copy of the loop. This
785 results in better code. */
786 /* We must limit the generic test to max_reg_before_loop, because only
787 these pseudo registers have valid regno_first_uid info. */
788 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_reg_before_loop
; ++r
)
789 if (REGNO_FIRST_UID (r
) > 0 && REGNO_FIRST_UID (r
) <= max_uid_for_loop
790 && REGNO_FIRST_LUID (r
) >= copy_start_luid
791 && REGNO_LAST_UID (r
) > 0 && REGNO_LAST_UID (r
) <= max_uid_for_loop
792 && REGNO_LAST_LUID (r
) <= copy_end_luid
)
794 /* However, we must also check for loop-carried dependencies.
795 If the value the pseudo has at the end of iteration X is
796 used by iteration X+1, then we can not use a different pseudo
797 for each unrolled copy of the loop. */
798 /* A pseudo is safe if regno_first_uid is a set, and this
799 set dominates all instructions from regno_first_uid to
801 /* ??? This check is simplistic. We would get better code if
802 this check was more sophisticated. */
803 if (set_dominates_use (r
, REGNO_FIRST_UID (r
), REGNO_LAST_UID (r
),
804 copy_start
, copy_end
))
807 if (loop_dump_stream
)
810 fprintf (loop_dump_stream
, "Marked reg %d as local\n", r
);
812 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
818 /* If this loop requires exit tests when unrolled, check to see if we
819 can precondition the loop so as to make the exit tests unnecessary.
820 Just like variable splitting, this is not safe if the loop is entered
821 via a jump to the bottom. Also, can not do this if no strength
822 reduce info, because precondition_loop_p uses this info. */
824 /* Must copy the loop body for preconditioning before the following
825 find_splittable_regs call since that will emit insns which need to
826 be after the preconditioned loop copies, but immediately before the
827 unrolled loop copies. */
829 /* Also, it is not safe to split induction variables for the preconditioned
830 copies of the loop body. If we split induction variables, then the code
831 assumes that each induction variable can be represented as a function
832 of its initial value and the loop iteration number. This is not true
833 in this case, because the last preconditioned copy of the loop body
834 could be any iteration from the first up to the `unroll_number-1'th,
835 depending on the initial value of the iteration variable. Therefore
836 we can not split induction variables here, because we can not calculate
837 their value. Hence, this code must occur before find_splittable_regs
840 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
842 rtx initial_value
, final_value
, increment
;
843 enum machine_mode mode
;
845 if (precondition_loop_p (loop
,
846 &initial_value
, &final_value
, &increment
,
851 int abs_inc
, neg_inc
;
852 enum rtx_code cc
= loop_info
->comparison_code
;
853 int less_p
= (cc
== LE
|| cc
== LEU
|| cc
== LT
|| cc
== LTU
);
854 int unsigned_p
= (cc
== LEU
|| cc
== GEU
|| cc
== LTU
|| cc
== GTU
);
856 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
858 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
, maxregnum
,
859 "unroll_loop_precondition");
860 global_const_equiv_varray
= map
->const_equiv_varray
;
862 init_reg_map (map
, maxregnum
);
864 /* Limit loop unrolling to 4, since this will make 7 copies of
866 if (unroll_number
> 4)
869 /* Save the absolute value of the increment, and also whether or
870 not it is negative. */
872 abs_inc
= INTVAL (increment
);
881 /* We must copy the final and initial values here to avoid
882 improperly shared rtl. */
883 final_value
= copy_rtx (final_value
);
884 initial_value
= copy_rtx (initial_value
);
886 /* Final value may have form of (PLUS val1 const1_rtx). We need
887 to convert it into general operand, so compute the real value. */
889 final_value
= force_operand (final_value
, NULL_RTX
);
890 if (!nonmemory_operand (final_value
, VOIDmode
))
891 final_value
= force_reg (mode
, final_value
);
893 /* Calculate the difference between the final and initial values.
894 Final value may be a (plus (reg x) (const_int 1)) rtx.
896 We have to deal with for (i = 0; --i < 6;) type loops.
897 For such loops the real final value is the first time the
898 loop variable overflows, so the diff we calculate is the
899 distance from the overflow value. This is 0 or ~0 for
900 unsigned loops depending on the direction, or INT_MAX,
901 INT_MAX+1 for signed loops. We really do not need the
902 exact value, since we are only interested in the diff
903 modulo the increment, and the increment is a power of 2,
904 so we can pretend that the overflow value is 0/~0. */
906 if (cc
== NE
|| less_p
!= neg_inc
)
907 diff
= simplify_gen_binary (MINUS
, mode
, final_value
,
910 diff
= simplify_gen_unary (neg_inc
? NOT
: NEG
, mode
,
911 initial_value
, mode
);
912 diff
= force_operand (diff
, NULL_RTX
);
914 /* Now calculate (diff % (unroll * abs (increment))) by using an
916 diff
= simplify_gen_binary (AND
, mode
, diff
,
917 GEN_INT (unroll_number
*abs_inc
- 1));
918 diff
= force_operand (diff
, NULL_RTX
);
920 /* Now emit a sequence of branches to jump to the proper precond
923 labels
= (rtx
*) xmalloc (sizeof (rtx
) * unroll_number
);
924 for (i
= 0; i
< unroll_number
; i
++)
925 labels
[i
] = gen_label_rtx ();
927 /* Check for the case where the initial value is greater than or
928 equal to the final value. In that case, we want to execute
929 exactly one loop iteration. The code below will fail for this
930 case. This check does not apply if the loop has a NE
931 comparison at the end. */
935 rtx incremented_initval
;
936 enum rtx_code cmp_code
;
939 = simplify_gen_binary (PLUS
, mode
, initial_value
, increment
);
941 = force_operand (incremented_initval
, NULL_RTX
);
944 ? (unsigned_p
? GEU
: GE
)
945 : (unsigned_p
? LEU
: LE
));
947 insn
= simplify_cmp_and_jump_insns (cmp_code
, mode
,
949 final_value
, labels
[1]);
951 predict_insn_def (insn
, PRED_LOOP_CONDITION
, TAKEN
);
954 /* Assuming the unroll_number is 4, and the increment is 2, then
955 for a negative increment: for a positive increment:
956 diff = 0,1 precond 0 diff = 0,7 precond 0
957 diff = 2,3 precond 3 diff = 1,2 precond 1
958 diff = 4,5 precond 2 diff = 3,4 precond 2
959 diff = 6,7 precond 1 diff = 5,6 precond 3 */
961 /* We only need to emit (unroll_number - 1) branches here, the
962 last case just falls through to the following code. */
964 /* ??? This would give better code if we emitted a tree of branches
965 instead of the current linear list of branches. */
967 for (i
= 0; i
< unroll_number
- 1; i
++)
970 enum rtx_code cmp_code
;
972 /* For negative increments, must invert the constant compared
973 against, except when comparing against zero. */
981 cmp_const
= unroll_number
- i
;
990 insn
= simplify_cmp_and_jump_insns (cmp_code
, mode
, diff
,
991 GEN_INT (abs_inc
*cmp_const
),
994 predict_insn (insn
, PRED_LOOP_PRECONDITIONING
,
995 REG_BR_PROB_BASE
/ (unroll_number
- i
));
998 /* If the increment is greater than one, then we need another branch,
999 to handle other cases equivalent to 0. */
1001 /* ??? This should be merged into the code above somehow to help
1002 simplify the code here, and reduce the number of branches emitted.
1003 For the negative increment case, the branch here could easily
1004 be merged with the `0' case branch above. For the positive
1005 increment case, it is not clear how this can be simplified. */
1010 enum rtx_code cmp_code
;
1014 cmp_const
= abs_inc
- 1;
1019 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
1023 simplify_cmp_and_jump_insns (cmp_code
, mode
, diff
,
1024 GEN_INT (cmp_const
), labels
[0]);
1027 sequence
= get_insns ();
1029 loop_insn_hoist (loop
, sequence
);
1031 /* Only the last copy of the loop body here needs the exit
1032 test, so set copy_end to exclude the compare/branch here,
1033 and then reset it inside the loop when get to the last
1036 if (GET_CODE (last_loop_insn
) == BARRIER
)
1037 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1038 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1040 copy_end
= PREV_INSN (last_loop_insn
);
1042 /* The immediately preceding insn may be a compare which
1043 we do not want to copy. */
1044 if (sets_cc0_p (PREV_INSN (copy_end
)))
1045 copy_end
= PREV_INSN (copy_end
);
1051 for (i
= 1; i
< unroll_number
; i
++)
1053 emit_label_after (labels
[unroll_number
- i
],
1054 PREV_INSN (loop_start
));
1056 memset ((char *) map
->insn_map
, 0, max_insnno
* sizeof (rtx
));
1057 memset ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1058 0, (VARRAY_SIZE (map
->const_equiv_varray
)
1059 * sizeof (struct const_equiv_data
)));
1062 for (j
= 0; j
< max_labelno
; j
++)
1064 set_label_in_map (map
, j
, gen_label_rtx ());
1066 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1070 = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1071 record_base_value (REGNO (map
->reg_map
[r
]),
1072 regno_reg_rtx
[r
], 0);
1074 /* The last copy needs the compare/branch insns at the end,
1075 so reset copy_end here if the loop ends with a conditional
1078 if (i
== unroll_number
- 1)
1080 if (GET_CODE (last_loop_insn
) == BARRIER
)
1081 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1083 copy_end
= last_loop_insn
;
1086 /* None of the copies are the `last_iteration', so just
1087 pass zero for that parameter. */
1088 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
, 0,
1089 unroll_type
, start_label
, loop_end
,
1090 loop_start
, copy_end
);
1092 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1094 if (GET_CODE (last_loop_insn
) == BARRIER
)
1096 insert_before
= PREV_INSN (last_loop_insn
);
1097 copy_end
= PREV_INSN (insert_before
);
1101 insert_before
= last_loop_insn
;
1103 /* The instruction immediately before the JUMP_INSN may
1104 be a compare instruction which we do not want to copy
1106 if (sets_cc0_p (PREV_INSN (insert_before
)))
1107 insert_before
= PREV_INSN (insert_before
);
1109 copy_end
= PREV_INSN (insert_before
);
1112 /* Set unroll type to MODULO now. */
1113 unroll_type
= UNROLL_MODULO
;
1114 loop_preconditioned
= 1;
1121 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1122 the loop unless all loops are being unrolled. */
1123 if (unroll_type
== UNROLL_NAIVE
&& ! flag_unroll_all_loops
)
1125 if (loop_dump_stream
)
1126 fprintf (loop_dump_stream
,
1127 "Unrolling failure: Naive unrolling not being done.\n");
1131 /* At this point, we are guaranteed to unroll the loop. */
1133 /* Keep track of the unroll factor for the loop. */
1134 loop_info
->unroll_number
= unroll_number
;
1136 /* And whether the loop has been preconditioned. */
1137 loop_info
->preconditioned
= loop_preconditioned
;
1139 /* Remember whether it was preconditioned for the second loop pass. */
1140 NOTE_PRECONDITIONED (loop
->end
) = loop_preconditioned
;
1142 /* For each biv and giv, determine whether it can be safely split into
1143 a different variable for each unrolled copy of the loop body.
1144 We precalculate and save this info here, since computing it is
1147 Do this before deleting any instructions from the loop, so that
1148 back_branch_in_range_p will work correctly. */
1150 if (splitting_not_safe
)
1153 temp
= find_splittable_regs (loop
, unroll_type
, unroll_number
);
1155 /* find_splittable_regs may have created some new registers, so must
1156 reallocate the reg_map with the new larger size, and must realloc
1157 the constant maps also. */
1159 maxregnum
= max_reg_num ();
1160 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
1162 init_reg_map (map
, maxregnum
);
1164 if (map
->const_equiv_varray
== 0)
1165 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1166 maxregnum
+ temp
* unroll_number
* 2,
1168 global_const_equiv_varray
= map
->const_equiv_varray
;
1170 /* Search the list of bivs and givs to find ones which need to be remapped
1171 when split, and set their reg_map entry appropriately. */
1173 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
1175 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1176 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1178 /* Currently, non-reduced/final-value givs are never split. */
1179 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1180 if (REGNO (v
->src_reg
) != bl
->regno
)
1181 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1185 /* Use our current register alignment and pointer flags. */
1186 map
->regno_pointer_align
= cfun
->emit
->regno_pointer_align
;
1187 map
->x_regno_reg_rtx
= cfun
->emit
->x_regno_reg_rtx
;
1189 /* If the loop is being partially unrolled, and the iteration variables
1190 are being split, and are being renamed for the split, then must fix up
1191 the compare/jump instruction at the end of the loop to refer to the new
1192 registers. This compare isn't copied, so the registers used in it
1193 will never be replaced if it isn't done here. */
1195 if (unroll_type
== UNROLL_MODULO
)
1197 insn
= NEXT_INSN (copy_end
);
1198 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1199 PATTERN (insn
) = remap_split_bivs (loop
, PATTERN (insn
));
1202 /* For unroll_number times, make a copy of each instruction
1203 between copy_start and copy_end, and insert these new instructions
1204 before the end of the loop. */
1206 for (i
= 0; i
< unroll_number
; i
++)
1208 memset ((char *) map
->insn_map
, 0, max_insnno
* sizeof (rtx
));
1209 memset ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0), 0,
1210 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1213 for (j
= 0; j
< max_labelno
; j
++)
1215 set_label_in_map (map
, j
, gen_label_rtx ());
1217 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1220 map
->reg_map
[r
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1221 record_base_value (REGNO (map
->reg_map
[r
]),
1222 regno_reg_rtx
[r
], 0);
1225 /* If loop starts with a branch to the test, then fix it so that
1226 it points to the test of the first unrolled copy of the loop. */
1227 if (i
== 0 && loop_start
!= copy_start
)
1229 insn
= PREV_INSN (copy_start
);
1230 pattern
= PATTERN (insn
);
1232 tem
= get_label_from_map (map
,
1234 (XEXP (SET_SRC (pattern
), 0)));
1235 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1237 /* Set the jump label so that it can be used by later loop unrolling
1239 JUMP_LABEL (insn
) = tem
;
1240 LABEL_NUSES (tem
)++;
1243 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
,
1244 i
== unroll_number
- 1, unroll_type
, start_label
,
1245 loop_end
, insert_before
, insert_before
);
1248 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1249 insn to be deleted. This prevents any runaway delete_insn call from
1250 more insns that it should, as it always stops at a CODE_LABEL. */
1252 /* Delete the compare and branch at the end of the loop if completely
1253 unrolling the loop. Deleting the backward branch at the end also
1254 deletes the code label at the start of the loop. This is done at
1255 the very end to avoid problems with back_branch_in_range_p. */
1257 if (unroll_type
== UNROLL_COMPLETELY
)
1258 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1260 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1262 /* Delete all of the original loop instructions. Don't delete the
1263 LOOP_BEG note, or the first code label in the loop. */
1265 insn
= NEXT_INSN (copy_start
);
1266 while (insn
!= safety_label
)
1268 /* ??? Don't delete named code labels. They will be deleted when the
1269 jump that references them is deleted. Otherwise, we end up deleting
1270 them twice, which causes them to completely disappear instead of turn
1271 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1272 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1273 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1274 associated LABEL_DECL to point to one of the new label instances. */
1275 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1276 if (insn
!= start_label
1277 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1278 && ! (GET_CODE (insn
) == NOTE
1279 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1280 insn
= delete_related_insns (insn
);
1282 insn
= NEXT_INSN (insn
);
1285 /* Can now delete the 'safety' label emitted to protect us from runaway
1286 delete_related_insns calls. */
1287 if (INSN_DELETED_P (safety_label
))
1289 delete_related_insns (safety_label
);
1291 /* If exit_label exists, emit it after the loop. Doing the emit here
1292 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1293 This is needed so that mostly_true_jump in reorg.c will treat jumps
1294 to this loop end label correctly, i.e. predict that they are usually
1297 emit_label_after (exit_label
, loop_end
);
1300 if (unroll_type
== UNROLL_COMPLETELY
)
1302 /* Remove the loop notes since this is no longer a loop. */
1304 delete_related_insns (loop
->vtop
);
1306 delete_related_insns (loop
->cont
);
1308 delete_related_insns (loop_start
);
1310 delete_related_insns (loop_end
);
1313 if (map
->const_equiv_varray
)
1314 VARRAY_FREE (map
->const_equiv_varray
);
1317 free (map
->label_map
);
1320 free (map
->insn_map
);
1321 free (splittable_regs
);
1322 free (splittable_regs_updates
);
1323 free (addr_combined_regs
);
1326 free (map
->reg_map
);
1330 /* A helper function for unroll_loop. Emit a compare and branch to
1331 satisfy (CMP OP1 OP2), but pass this through the simplifier first.
1332 If the branch turned out to be conditional, return it, otherwise
1336 simplify_cmp_and_jump_insns (code
, mode
, op0
, op1
, label
)
1338 enum machine_mode mode
;
1339 rtx op0
, op1
, label
;
1343 t
= simplify_relational_operation (code
, mode
, op0
, op1
);
1346 enum rtx_code scode
= signed_condition (code
);
1347 emit_cmp_and_jump_insns (op0
, op1
, scode
, NULL_RTX
, mode
,
1348 code
!= scode
, label
);
1349 insn
= get_last_insn ();
1351 JUMP_LABEL (insn
) = label
;
1352 LABEL_NUSES (label
) += 1;
1356 else if (t
== const_true_rtx
)
1358 insn
= emit_jump_insn (gen_jump (label
));
1360 JUMP_LABEL (insn
) = label
;
1361 LABEL_NUSES (label
) += 1;
1367 /* Return true if the loop can be safely, and profitably, preconditioned
1368 so that the unrolled copies of the loop body don't need exit tests.
1370 This only works if final_value, initial_value and increment can be
1371 determined, and if increment is a constant power of 2.
1372 If increment is not a power of 2, then the preconditioning modulo
1373 operation would require a real modulo instead of a boolean AND, and this
1374 is not considered `profitable'. */
1376 /* ??? If the loop is known to be executed very many times, or the machine
1377 has a very cheap divide instruction, then preconditioning is a win even
1378 when the increment is not a power of 2. Use RTX_COST to compute
1379 whether divide is cheap.
1380 ??? A divide by constant doesn't actually need a divide, look at
1381 expand_divmod. The reduced cost of this optimized modulo is not
1382 reflected in RTX_COST. */
1385 precondition_loop_p (loop
, initial_value
, final_value
, increment
, mode
)
1386 const struct loop
*loop
;
1387 rtx
*initial_value
, *final_value
, *increment
;
1388 enum machine_mode
*mode
;
1390 rtx loop_start
= loop
->start
;
1391 struct loop_info
*loop_info
= LOOP_INFO (loop
);
1393 if (loop_info
->n_iterations
> 0)
1395 if (INTVAL (loop_info
->increment
) > 0)
1397 *initial_value
= const0_rtx
;
1398 *increment
= const1_rtx
;
1399 *final_value
= GEN_INT (loop_info
->n_iterations
);
1403 *initial_value
= GEN_INT (loop_info
->n_iterations
);
1404 *increment
= constm1_rtx
;
1405 *final_value
= const0_rtx
;
1409 if (loop_dump_stream
)
1411 fputs ("Preconditioning: Success, number of iterations known, ",
1413 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
1414 loop_info
->n_iterations
);
1415 fputs (".\n", loop_dump_stream
);
1420 if (loop_info
->iteration_var
== 0)
1422 if (loop_dump_stream
)
1423 fprintf (loop_dump_stream
,
1424 "Preconditioning: Could not find iteration variable.\n");
1427 else if (loop_info
->initial_value
== 0)
1429 if (loop_dump_stream
)
1430 fprintf (loop_dump_stream
,
1431 "Preconditioning: Could not find initial value.\n");
1434 else if (loop_info
->increment
== 0)
1436 if (loop_dump_stream
)
1437 fprintf (loop_dump_stream
,
1438 "Preconditioning: Could not find increment value.\n");
1441 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1443 if (loop_dump_stream
)
1444 fprintf (loop_dump_stream
,
1445 "Preconditioning: Increment not a constant.\n");
1448 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1449 && (exact_log2 (-INTVAL (loop_info
->increment
)) < 0))
1451 if (loop_dump_stream
)
1452 fprintf (loop_dump_stream
,
1453 "Preconditioning: Increment not a constant power of 2.\n");
1457 /* Unsigned_compare and compare_dir can be ignored here, since they do
1458 not matter for preconditioning. */
1460 if (loop_info
->final_value
== 0)
1462 if (loop_dump_stream
)
1463 fprintf (loop_dump_stream
,
1464 "Preconditioning: EQ comparison loop.\n");
1468 /* Must ensure that final_value is invariant, so call
1469 loop_invariant_p to check. Before doing so, must check regno
1470 against max_reg_before_loop to make sure that the register is in
1471 the range covered by loop_invariant_p. If it isn't, then it is
1472 most likely a biv/giv which by definition are not invariant. */
1473 if ((GET_CODE (loop_info
->final_value
) == REG
1474 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1475 || (GET_CODE (loop_info
->final_value
) == PLUS
1476 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1477 || ! loop_invariant_p (loop
, loop_info
->final_value
))
1479 if (loop_dump_stream
)
1480 fprintf (loop_dump_stream
,
1481 "Preconditioning: Final value not invariant.\n");
1485 /* Fail for floating point values, since the caller of this function
1486 does not have code to deal with them. */
1487 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1488 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1490 if (loop_dump_stream
)
1491 fprintf (loop_dump_stream
,
1492 "Preconditioning: Floating point final or initial value.\n");
1496 /* Fail if loop_info->iteration_var is not live before loop_start,
1497 since we need to test its value in the preconditioning code. */
1499 if (REGNO_FIRST_LUID (REGNO (loop_info
->iteration_var
))
1500 > INSN_LUID (loop_start
))
1502 if (loop_dump_stream
)
1503 fprintf (loop_dump_stream
,
1504 "Preconditioning: Iteration var not live before loop start.\n");
1508 /* Note that loop_iterations biases the initial value for GIV iterators
1509 such as "while (i-- > 0)" so that we can calculate the number of
1510 iterations just like for BIV iterators.
1512 Also note that the absolute values of initial_value and
1513 final_value are unimportant as only their difference is used for
1514 calculating the number of loop iterations. */
1515 *initial_value
= loop_info
->initial_value
;
1516 *increment
= loop_info
->increment
;
1517 *final_value
= loop_info
->final_value
;
1519 /* Decide what mode to do these calculations in. Choose the larger
1520 of final_value's mode and initial_value's mode, or a full-word if
1521 both are constants. */
1522 *mode
= GET_MODE (*final_value
);
1523 if (*mode
== VOIDmode
)
1525 *mode
= GET_MODE (*initial_value
);
1526 if (*mode
== VOIDmode
)
1529 else if (*mode
!= GET_MODE (*initial_value
)
1530 && (GET_MODE_SIZE (*mode
)
1531 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1532 *mode
= GET_MODE (*initial_value
);
1535 if (loop_dump_stream
)
1536 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1540 /* All pseudo-registers must be mapped to themselves. Two hard registers
1541 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1542 REGNUM, to avoid function-inlining specific conversions of these
1543 registers. All other hard regs can not be mapped because they may be
1548 init_reg_map (map
, maxregnum
)
1549 struct inline_remap
*map
;
1554 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1555 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1556 /* Just clear the rest of the entries. */
1557 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1558 map
->reg_map
[i
] = 0;
1560 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1561 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1562 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1563 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1566 /* Strength-reduction will often emit code for optimized biv/givs which
1567 calculates their value in a temporary register, and then copies the result
1568 to the iv. This procedure reconstructs the pattern computing the iv;
1569 verifying that all operands are of the proper form.
1571 PATTERN must be the result of single_set.
1572 The return value is the amount that the giv is incremented by. */
1575 calculate_giv_inc (pattern
, src_insn
, regno
)
1576 rtx pattern
, src_insn
;
1580 rtx increment_total
= 0;
1584 /* Verify that we have an increment insn here. First check for a plus
1585 as the set source. */
1586 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1588 /* SR sometimes computes the new giv value in a temp, then copies it
1590 src_insn
= PREV_INSN (src_insn
);
1591 pattern
= single_set (src_insn
);
1592 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1595 /* The last insn emitted is not needed, so delete it to avoid confusing
1596 the second cse pass. This insn sets the giv unnecessarily. */
1597 delete_related_insns (get_last_insn ());
1600 /* Verify that we have a constant as the second operand of the plus. */
1601 increment
= XEXP (SET_SRC (pattern
), 1);
1602 if (GET_CODE (increment
) != CONST_INT
)
1604 /* SR sometimes puts the constant in a register, especially if it is
1605 too big to be an add immed operand. */
1606 increment
= find_last_value (increment
, &src_insn
, NULL_RTX
, 0);
1608 /* SR may have used LO_SUM to compute the constant if it is too large
1609 for a load immed operand. In this case, the constant is in operand
1610 one of the LO_SUM rtx. */
1611 if (GET_CODE (increment
) == LO_SUM
)
1612 increment
= XEXP (increment
, 1);
1614 /* Some ports store large constants in memory and add a REG_EQUAL
1615 note to the store insn. */
1616 else if (GET_CODE (increment
) == MEM
)
1618 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1620 increment
= XEXP (note
, 0);
1623 else if (GET_CODE (increment
) == IOR
1624 || GET_CODE (increment
) == ASHIFT
1625 || GET_CODE (increment
) == PLUS
)
1627 /* The rs6000 port loads some constants with IOR.
1628 The alpha port loads some constants with ASHIFT and PLUS. */
1629 rtx second_part
= XEXP (increment
, 1);
1630 enum rtx_code code
= GET_CODE (increment
);
1632 increment
= find_last_value (XEXP (increment
, 0),
1633 &src_insn
, NULL_RTX
, 0);
1634 /* Don't need the last insn anymore. */
1635 delete_related_insns (get_last_insn ());
1637 if (GET_CODE (second_part
) != CONST_INT
1638 || GET_CODE (increment
) != CONST_INT
)
1642 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1643 else if (code
== PLUS
)
1644 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1646 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1649 if (GET_CODE (increment
) != CONST_INT
)
1652 /* The insn loading the constant into a register is no longer needed,
1654 delete_related_insns (get_last_insn ());
1657 if (increment_total
)
1658 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1660 increment_total
= increment
;
1662 /* Check that the source register is the same as the register we expected
1663 to see as the source. If not, something is seriously wrong. */
1664 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1665 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1667 /* Some machines (e.g. the romp), may emit two add instructions for
1668 certain constants, so lets try looking for another add immediately
1669 before this one if we have only seen one add insn so far. */
1675 src_insn
= PREV_INSN (src_insn
);
1676 pattern
= single_set (src_insn
);
1678 delete_related_insns (get_last_insn ());
1686 return increment_total
;
1689 /* Copy REG_NOTES, except for insn references, because not all insn_map
1690 entries are valid yet. We do need to copy registers now though, because
1691 the reg_map entries can change during copying. */
1694 initial_reg_note_copy (notes
, map
)
1696 struct inline_remap
*map
;
1703 copy
= rtx_alloc (GET_CODE (notes
));
1704 PUT_REG_NOTE_KIND (copy
, REG_NOTE_KIND (notes
));
1706 if (GET_CODE (notes
) == EXPR_LIST
)
1707 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
, 0);
1708 else if (GET_CODE (notes
) == INSN_LIST
)
1709 /* Don't substitute for these yet. */
1710 XEXP (copy
, 0) = copy_rtx (XEXP (notes
, 0));
1714 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1719 /* Fixup insn references in copied REG_NOTES. */
1722 final_reg_note_copy (notesp
, map
)
1724 struct inline_remap
*map
;
1730 if (GET_CODE (note
) == INSN_LIST
)
1732 /* Sometimes, we have a REG_WAS_0 note that points to a
1733 deleted instruction. In that case, we can just delete the
1735 if (REG_NOTE_KIND (note
) == REG_WAS_0
)
1737 *notesp
= XEXP (note
, 1);
1742 rtx insn
= map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1744 /* If we failed to remap the note, something is awry.
1745 Allow REG_LABEL as it may reference label outside
1746 the unrolled loop. */
1749 if (REG_NOTE_KIND (note
) != REG_LABEL
)
1753 XEXP (note
, 0) = insn
;
1757 notesp
= &XEXP (note
, 1);
1761 /* Copy each instruction in the loop, substituting from map as appropriate.
1762 This is very similar to a loop in expand_inline_function. */
1765 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1766 unroll_type
, start_label
, loop_end
, insert_before
,
1769 rtx copy_start
, copy_end
;
1770 struct inline_remap
*map
;
1773 enum unroll_types unroll_type
;
1774 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1776 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
1778 rtx set
, tem
, copy
= NULL_RTX
;
1779 int dest_reg_was_split
, i
;
1783 rtx final_label
= 0;
1784 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1786 /* If this isn't the last iteration, then map any references to the
1787 start_label to final_label. Final label will then be emitted immediately
1788 after the end of this loop body if it was ever used.
1790 If this is the last iteration, then map references to the start_label
1792 if (! last_iteration
)
1794 final_label
= gen_label_rtx ();
1795 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), final_label
);
1798 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1805 insn
= NEXT_INSN (insn
);
1807 map
->orig_asm_operands_vector
= 0;
1809 switch (GET_CODE (insn
))
1812 pattern
= PATTERN (insn
);
1816 /* Check to see if this is a giv that has been combined with
1817 some split address givs. (Combined in the sense that
1818 `combine_givs' in loop.c has put two givs in the same register.)
1819 In this case, we must search all givs based on the same biv to
1820 find the address givs. Then split the address givs.
1821 Do this before splitting the giv, since that may map the
1822 SET_DEST to a new register. */
1824 if ((set
= single_set (insn
))
1825 && GET_CODE (SET_DEST (set
)) == REG
1826 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1828 struct iv_class
*bl
;
1829 struct induction
*v
, *tv
;
1830 unsigned int regno
= REGNO (SET_DEST (set
));
1832 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1833 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
1835 /* Although the giv_inc amount is not needed here, we must call
1836 calculate_giv_inc here since it might try to delete the
1837 last insn emitted. If we wait until later to call it,
1838 we might accidentally delete insns generated immediately
1839 below by emit_unrolled_add. */
1841 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1843 /* Now find all address giv's that were combined with this
1845 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1846 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1850 /* If this DEST_ADDR giv was not split, then ignore it. */
1851 if (*tv
->location
!= tv
->dest_reg
)
1854 /* Scale this_giv_inc if the multiplicative factors of
1855 the two givs are different. */
1856 this_giv_inc
= INTVAL (giv_inc
);
1857 if (tv
->mult_val
!= v
->mult_val
)
1858 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1859 * INTVAL (tv
->mult_val
));
1861 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1862 *tv
->location
= tv
->dest_reg
;
1864 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1866 /* Must emit an insn to increment the split address
1867 giv. Add in the const_adjust field in case there
1868 was a constant eliminated from the address. */
1869 rtx value
, dest_reg
;
1871 /* tv->dest_reg will be either a bare register,
1872 or else a register plus a constant. */
1873 if (GET_CODE (tv
->dest_reg
) == REG
)
1874 dest_reg
= tv
->dest_reg
;
1876 dest_reg
= XEXP (tv
->dest_reg
, 0);
1878 /* Check for shared address givs, and avoid
1879 incrementing the shared pseudo reg more than
1881 if (! tv
->same_insn
&& ! tv
->shared
)
1883 /* tv->dest_reg may actually be a (PLUS (REG)
1884 (CONST)) here, so we must call plus_constant
1885 to add the const_adjust amount before calling
1886 emit_unrolled_add below. */
1887 value
= plus_constant (tv
->dest_reg
,
1890 if (GET_CODE (value
) == PLUS
)
1892 /* The constant could be too large for an add
1893 immediate, so can't directly emit an insn
1895 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1900 /* Reset the giv to be just the register again, in case
1901 it is used after the set we have just emitted.
1902 We must subtract the const_adjust factor added in
1904 tv
->dest_reg
= plus_constant (dest_reg
,
1906 *tv
->location
= tv
->dest_reg
;
1911 /* If this is a setting of a splittable variable, then determine
1912 how to split the variable, create a new set based on this split,
1913 and set up the reg_map so that later uses of the variable will
1914 use the new split variable. */
1916 dest_reg_was_split
= 0;
1918 if ((set
= single_set (insn
))
1919 && GET_CODE (SET_DEST (set
)) == REG
1920 && splittable_regs
[REGNO (SET_DEST (set
))])
1922 unsigned int regno
= REGNO (SET_DEST (set
));
1923 unsigned int src_regno
;
1925 dest_reg_was_split
= 1;
1927 giv_dest_reg
= SET_DEST (set
);
1928 giv_src_reg
= giv_dest_reg
;
1929 /* Compute the increment value for the giv, if it wasn't
1930 already computed above. */
1932 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1934 src_regno
= REGNO (giv_src_reg
);
1936 if (unroll_type
== UNROLL_COMPLETELY
)
1938 /* Completely unrolling the loop. Set the induction
1939 variable to a known constant value. */
1941 /* The value in splittable_regs may be an invariant
1942 value, so we must use plus_constant here. */
1943 splittable_regs
[regno
]
1944 = plus_constant (splittable_regs
[src_regno
],
1947 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1949 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1950 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1954 /* The splittable_regs value must be a REG or a
1955 CONST_INT, so put the entire value in the giv_src_reg
1957 giv_src_reg
= splittable_regs
[regno
];
1958 giv_inc
= const0_rtx
;
1963 /* Partially unrolling loop. Create a new pseudo
1964 register for the iteration variable, and set it to
1965 be a constant plus the original register. Except
1966 on the last iteration, when the result has to
1967 go back into the original iteration var register. */
1969 /* Handle bivs which must be mapped to a new register
1970 when split. This happens for bivs which need their
1971 final value set before loop entry. The new register
1972 for the biv was stored in the biv's first struct
1973 induction entry by find_splittable_regs. */
1975 if (regno
< ivs
->n_regs
1976 && REG_IV_TYPE (ivs
, regno
) == BASIC_INDUCT
)
1978 giv_src_reg
= REG_IV_CLASS (ivs
, regno
)->biv
->src_reg
;
1979 giv_dest_reg
= giv_src_reg
;
1983 /* If non-reduced/final-value givs were split, then
1984 this would have to remap those givs also. See
1985 find_splittable_regs. */
1988 splittable_regs
[regno
]
1989 = simplify_gen_binary (PLUS
, GET_MODE (giv_src_reg
),
1991 splittable_regs
[src_regno
]);
1992 giv_inc
= splittable_regs
[regno
];
1994 /* Now split the induction variable by changing the dest
1995 of this insn to a new register, and setting its
1996 reg_map entry to point to this new register.
1998 If this is the last iteration, and this is the last insn
1999 that will update the iv, then reuse the original dest,
2000 to ensure that the iv will have the proper value when
2001 the loop exits or repeats.
2003 Using splittable_regs_updates here like this is safe,
2004 because it can only be greater than one if all
2005 instructions modifying the iv are always executed in
2008 if (! last_iteration
2009 || (splittable_regs_updates
[regno
]-- != 1))
2011 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
2013 map
->reg_map
[regno
] = tem
;
2014 record_base_value (REGNO (tem
),
2015 giv_inc
== const0_rtx
2017 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
2018 giv_src_reg
, giv_inc
),
2022 map
->reg_map
[regno
] = giv_src_reg
;
2025 /* The constant being added could be too large for an add
2026 immediate, so can't directly emit an insn here. */
2027 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
2028 copy
= get_last_insn ();
2029 pattern
= PATTERN (copy
);
2033 pattern
= copy_rtx_and_substitute (pattern
, map
, 0);
2034 copy
= emit_insn (pattern
);
2036 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2037 INSN_SCOPE (copy
) = INSN_SCOPE (insn
);
2039 /* If there is a REG_EQUAL note present whose value
2040 is not loop invariant, then delete it, since it
2041 may cause problems with later optimization passes. */
2042 if ((tem
= find_reg_note (copy
, REG_EQUAL
, NULL_RTX
))
2043 && !loop_invariant_p (loop
, XEXP (tem
, 0)))
2044 remove_note (copy
, tem
);
2047 /* If this insn is setting CC0, it may need to look at
2048 the insn that uses CC0 to see what type of insn it is.
2049 In that case, the call to recog via validate_change will
2050 fail. So don't substitute constants here. Instead,
2051 do it when we emit the following insn.
2053 For example, see the pyr.md file. That machine has signed and
2054 unsigned compares. The compare patterns must check the
2055 following branch insn to see which what kind of compare to
2058 If the previous insn set CC0, substitute constants on it as
2060 if (sets_cc0_p (PATTERN (copy
)) != 0)
2065 try_constants (cc0_insn
, map
);
2067 try_constants (copy
, map
);
2070 try_constants (copy
, map
);
2073 /* Make split induction variable constants `permanent' since we
2074 know there are no backward branches across iteration variable
2075 settings which would invalidate this. */
2076 if (dest_reg_was_split
)
2078 int regno
= REGNO (SET_DEST (set
));
2080 if ((size_t) regno
< VARRAY_SIZE (map
->const_equiv_varray
)
2081 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
2083 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
2088 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2089 copy
= emit_jump_insn (pattern
);
2090 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2091 INSN_SCOPE (copy
) = INSN_SCOPE (insn
);
2093 if (JUMP_LABEL (insn
))
2095 JUMP_LABEL (copy
) = get_label_from_map (map
,
2097 (JUMP_LABEL (insn
)));
2098 LABEL_NUSES (JUMP_LABEL (copy
))++;
2100 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
2101 && ! last_iteration
)
2104 /* This is a branch to the beginning of the loop; this is the
2105 last insn being copied; and this is not the last iteration.
2106 In this case, we want to change the original fall through
2107 case to be a branch past the end of the loop, and the
2108 original jump label case to fall_through. */
2110 if (!invert_jump (copy
, exit_label
, 0))
2113 rtx lab
= gen_label_rtx ();
2114 /* Can't do it by reversing the jump (probably because we
2115 couldn't reverse the conditions), so emit a new
2116 jump_insn after COPY, and redirect the jump around
2118 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2119 JUMP_LABEL (jmp
) = exit_label
;
2120 LABEL_NUSES (exit_label
)++;
2121 jmp
= emit_barrier_after (jmp
);
2122 emit_label_after (lab
, jmp
);
2123 LABEL_NUSES (lab
) = 0;
2124 if (!redirect_jump (copy
, lab
, 0))
2131 try_constants (cc0_insn
, map
);
2134 try_constants (copy
, map
);
2136 /* Set the jump label of COPY correctly to avoid problems with
2137 later passes of unroll_loop, if INSN had jump label set. */
2138 if (JUMP_LABEL (insn
))
2142 /* Can't use the label_map for every insn, since this may be
2143 the backward branch, and hence the label was not mapped. */
2144 if ((set
= single_set (copy
)))
2146 tem
= SET_SRC (set
);
2147 if (GET_CODE (tem
) == LABEL_REF
)
2148 label
= XEXP (tem
, 0);
2149 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2151 if (XEXP (tem
, 1) != pc_rtx
)
2152 label
= XEXP (XEXP (tem
, 1), 0);
2154 label
= XEXP (XEXP (tem
, 2), 0);
2158 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2159 JUMP_LABEL (copy
) = label
;
2162 /* An unrecognizable jump insn, probably the entry jump
2163 for a switch statement. This label must have been mapped,
2164 so just use the label_map to get the new jump label. */
2166 = get_label_from_map (map
,
2167 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2170 /* If this is a non-local jump, then must increase the label
2171 use count so that the label will not be deleted when the
2172 original jump is deleted. */
2173 LABEL_NUSES (JUMP_LABEL (copy
))++;
2175 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2176 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2178 rtx pat
= PATTERN (copy
);
2179 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2180 int len
= XVECLEN (pat
, diff_vec_p
);
2183 for (i
= 0; i
< len
; i
++)
2184 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2187 /* If this used to be a conditional jump insn but whose branch
2188 direction is now known, we must do something special. */
2189 if (any_condjump_p (insn
) && onlyjump_p (insn
) && map
->last_pc_value
)
2192 /* If the previous insn set cc0 for us, delete it. */
2193 if (only_sets_cc0_p (PREV_INSN (copy
)))
2194 delete_related_insns (PREV_INSN (copy
));
2197 /* If this is now a no-op, delete it. */
2198 if (map
->last_pc_value
== pc_rtx
)
2204 /* Otherwise, this is unconditional jump so we must put a
2205 BARRIER after it. We could do some dead code elimination
2206 here, but jump.c will do it just as well. */
2212 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2213 copy
= emit_call_insn (pattern
);
2214 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2215 INSN_SCOPE (copy
) = INSN_SCOPE (insn
);
2216 SIBLING_CALL_P (copy
) = SIBLING_CALL_P (insn
);
2218 /* Because the USAGE information potentially contains objects other
2219 than hard registers, we need to copy it. */
2220 CALL_INSN_FUNCTION_USAGE (copy
)
2221 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
),
2226 try_constants (cc0_insn
, map
);
2229 try_constants (copy
, map
);
2231 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2232 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2233 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2237 /* If this is the loop start label, then we don't need to emit a
2238 copy of this label since no one will use it. */
2240 if (insn
!= start_label
)
2242 copy
= emit_label (get_label_from_map (map
,
2243 CODE_LABEL_NUMBER (insn
)));
2249 copy
= emit_barrier ();
2253 /* VTOP and CONT notes are valid only before the loop exit test.
2254 If placed anywhere else, loop may generate bad code. */
2255 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2256 the associated rtl. We do not want to share the structure in
2259 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2260 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED_LABEL
2261 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2262 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2263 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2264 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2265 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2266 NOTE_LINE_NUMBER (insn
));
2275 map
->insn_map
[INSN_UID (insn
)] = copy
;
2277 while (insn
!= copy_end
);
2279 /* Now finish coping the REG_NOTES. */
2283 insn
= NEXT_INSN (insn
);
2284 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2285 || GET_CODE (insn
) == CALL_INSN
)
2286 && map
->insn_map
[INSN_UID (insn
)])
2287 final_reg_note_copy (®_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2289 while (insn
!= copy_end
);
2291 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2292 each of these notes here, since there may be some important ones, such as
2293 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2294 iteration, because the original notes won't be deleted.
2296 We can't use insert_before here, because when from preconditioning,
2297 insert_before points before the loop. We can't use copy_end, because
2298 there may be insns already inserted after it (which we don't want to
2299 copy) when not from preconditioning code. */
2301 if (! last_iteration
)
2303 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2305 /* VTOP notes are valid only before the loop exit test.
2306 If placed anywhere else, loop may generate bad code.
2307 Although COPY_NOTES_FROM will be at most one or two (for cc0)
2308 instructions before the last insn in the loop, COPY_NOTES_FROM
2309 can be a NOTE_INSN_LOOP_CONT note if there is no VTOP note,
2310 as in a do .. while loop. */
2311 if (GET_CODE (insn
) == NOTE
2312 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2313 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2314 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2315 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2316 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2320 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2321 emit_label (final_label
);
2325 loop_insn_emit_before (loop
, 0, insert_before
, tem
);
2328 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2329 emitted. This will correctly handle the case where the increment value
2330 won't fit in the immediate field of a PLUS insns. */
2333 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2334 rtx dest_reg
, src_reg
, increment
;
2338 result
= expand_simple_binop (GET_MODE (dest_reg
), PLUS
, src_reg
, increment
,
2339 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2341 if (dest_reg
!= result
)
2342 emit_move_insn (dest_reg
, result
);
2345 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2346 is a backward branch in that range that branches to somewhere between
2347 LOOP->START and INSN. Returns 0 otherwise. */
2349 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2350 In practice, this is not a problem, because this function is seldom called,
2351 and uses a negligible amount of CPU time on average. */
2354 back_branch_in_range_p (loop
, insn
)
2355 const struct loop
*loop
;
2358 rtx p
, q
, target_insn
;
2359 rtx loop_start
= loop
->start
;
2360 rtx loop_end
= loop
->end
;
2361 rtx orig_loop_end
= loop
->end
;
2363 /* Stop before we get to the backward branch at the end of the loop. */
2364 loop_end
= prev_nonnote_insn (loop_end
);
2365 if (GET_CODE (loop_end
) == BARRIER
)
2366 loop_end
= PREV_INSN (loop_end
);
2368 /* Check in case insn has been deleted, search forward for first non
2369 deleted insn following it. */
2370 while (INSN_DELETED_P (insn
))
2371 insn
= NEXT_INSN (insn
);
2373 /* Check for the case where insn is the last insn in the loop. Deal
2374 with the case where INSN was a deleted loop test insn, in which case
2375 it will now be the NOTE_LOOP_END. */
2376 if (insn
== loop_end
|| insn
== orig_loop_end
)
2379 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2381 if (GET_CODE (p
) == JUMP_INSN
)
2383 target_insn
= JUMP_LABEL (p
);
2385 /* Search from loop_start to insn, to see if one of them is
2386 the target_insn. We can't use INSN_LUID comparisons here,
2387 since insn may not have an LUID entry. */
2388 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2389 if (q
== target_insn
)
2397 /* Try to generate the simplest rtx for the expression
2398 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2402 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2403 rtx mult1
, mult2
, add1
;
2404 enum machine_mode mode
;
2409 /* The modes must all be the same. This should always be true. For now,
2410 check to make sure. */
2411 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2412 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2413 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2416 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2417 will be a constant. */
2418 if (GET_CODE (mult1
) == CONST_INT
)
2425 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2427 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2429 /* Again, put the constant second. */
2430 if (GET_CODE (add1
) == CONST_INT
)
2437 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2439 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2444 /* Searches the list of induction struct's for the biv BL, to try to calculate
2445 the total increment value for one iteration of the loop as a constant.
2447 Returns the increment value as an rtx, simplified as much as possible,
2448 if it can be calculated. Otherwise, returns 0. */
2451 biv_total_increment (bl
)
2452 const struct iv_class
*bl
;
2454 struct induction
*v
;
2457 /* For increment, must check every instruction that sets it. Each
2458 instruction must be executed only once each time through the loop.
2459 To verify this, we check that the insn is always executed, and that
2460 there are no backward branches after the insn that branch to before it.
2461 Also, the insn must have a mult_val of one (to make sure it really is
2464 result
= const0_rtx
;
2465 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2467 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2468 && ! v
->maybe_multiple
2469 && SCALAR_INT_MODE_P (v
->mode
))
2470 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2478 /* For each biv and giv, determine whether it can be safely split into
2479 a different variable for each unrolled copy of the loop body. If it
2480 is safe to split, then indicate that by saving some useful info
2481 in the splittable_regs array.
2483 If the loop is being completely unrolled, then splittable_regs will hold
2484 the current value of the induction variable while the loop is unrolled.
2485 It must be set to the initial value of the induction variable here.
2486 Otherwise, splittable_regs will hold the difference between the current
2487 value of the induction variable and the value the induction variable had
2488 at the top of the loop. It must be set to the value 0 here.
2490 Returns the total number of instructions that set registers that are
2493 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2494 constant values are unnecessary, since we can easily calculate increment
2495 values in this case even if nothing is constant. The increment value
2496 should not involve a multiply however. */
2498 /* ?? Even if the biv/giv increment values aren't constant, it may still
2499 be beneficial to split the variable if the loop is only unrolled a few
2500 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2503 find_splittable_regs (loop
, unroll_type
, unroll_number
)
2504 const struct loop
*loop
;
2505 enum unroll_types unroll_type
;
2508 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
2509 struct iv_class
*bl
;
2510 struct induction
*v
;
2512 rtx biv_final_value
;
2516 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
2518 /* Biv_total_increment must return a constant value,
2519 otherwise we can not calculate the split values. */
2521 increment
= biv_total_increment (bl
);
2522 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2525 /* The loop must be unrolled completely, or else have a known number
2526 of iterations and only one exit, or else the biv must be dead
2527 outside the loop, or else the final value must be known. Otherwise,
2528 it is unsafe to split the biv since it may not have the proper
2529 value on loop exit. */
2531 /* loop_number_exit_count is nonzero if the loop has an exit other than
2532 a fall through at the end. */
2535 biv_final_value
= 0;
2536 if (unroll_type
!= UNROLL_COMPLETELY
2537 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2538 && (REGNO_LAST_LUID (bl
->regno
) >= INSN_LUID (loop
->end
)
2540 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2541 || (REGNO_FIRST_LUID (bl
->regno
)
2542 < INSN_LUID (bl
->init_insn
))
2543 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2544 && ! (biv_final_value
= final_biv_value (loop
, bl
)))
2547 /* If any of the insns setting the BIV don't do so with a simple
2548 PLUS, we don't know how to split it. */
2549 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2550 if ((tem
= single_set (v
->insn
)) == 0
2551 || GET_CODE (SET_DEST (tem
)) != REG
2552 || REGNO (SET_DEST (tem
)) != bl
->regno
2553 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2556 /* If final value is nonzero, then must emit an instruction which sets
2557 the value of the biv to the proper value. This is done after
2558 handling all of the givs, since some of them may need to use the
2559 biv's value in their initialization code. */
2561 /* This biv is splittable. If completely unrolling the loop, save
2562 the biv's initial value. Otherwise, save the constant zero. */
2564 if (biv_splittable
== 1)
2566 if (unroll_type
== UNROLL_COMPLETELY
)
2568 /* If the initial value of the biv is itself (i.e. it is too
2569 complicated for strength_reduce to compute), or is a hard
2570 register, or it isn't invariant, then we must create a new
2571 pseudo reg to hold the initial value of the biv. */
2573 if (GET_CODE (bl
->initial_value
) == REG
2574 && (REGNO (bl
->initial_value
) == bl
->regno
2575 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2576 || ! loop_invariant_p (loop
, bl
->initial_value
)))
2578 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2580 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2581 loop_insn_hoist (loop
,
2582 gen_move_insn (tem
, bl
->biv
->src_reg
));
2584 if (loop_dump_stream
)
2585 fprintf (loop_dump_stream
,
2586 "Biv %d initial value remapped to %d.\n",
2587 bl
->regno
, REGNO (tem
));
2589 splittable_regs
[bl
->regno
] = tem
;
2592 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2595 splittable_regs
[bl
->regno
] = const0_rtx
;
2597 /* Save the number of instructions that modify the biv, so that
2598 we can treat the last one specially. */
2600 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2601 result
+= bl
->biv_count
;
2603 if (loop_dump_stream
)
2604 fprintf (loop_dump_stream
,
2605 "Biv %d safe to split.\n", bl
->regno
);
2608 /* Check every giv that depends on this biv to see whether it is
2609 splittable also. Even if the biv isn't splittable, givs which
2610 depend on it may be splittable if the biv is live outside the
2611 loop, and the givs aren't. */
2613 result
+= find_splittable_givs (loop
, bl
, unroll_type
, increment
,
2616 /* If final value is nonzero, then must emit an instruction which sets
2617 the value of the biv to the proper value. This is done after
2618 handling all of the givs, since some of them may need to use the
2619 biv's value in their initialization code. */
2620 if (biv_final_value
)
2622 /* If the loop has multiple exits, emit the insns before the
2623 loop to ensure that it will always be executed no matter
2624 how the loop exits. Otherwise emit the insn after the loop,
2625 since this is slightly more efficient. */
2626 if (! loop
->exit_count
)
2627 loop_insn_sink (loop
, gen_move_insn (bl
->biv
->src_reg
,
2631 /* Create a new register to hold the value of the biv, and then
2632 set the biv to its final value before the loop start. The biv
2633 is set to its final value before loop start to ensure that
2634 this insn will always be executed, no matter how the loop
2636 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2637 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2639 loop_insn_hoist (loop
, gen_move_insn (tem
, bl
->biv
->src_reg
));
2640 loop_insn_hoist (loop
, gen_move_insn (bl
->biv
->src_reg
,
2643 if (loop_dump_stream
)
2644 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2645 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2647 /* Set up the mapping from the original biv register to the new
2649 bl
->biv
->src_reg
= tem
;
2656 /* For every giv based on the biv BL, check to determine whether it is
2657 splittable. This is a subroutine to find_splittable_regs ().
2659 Return the number of instructions that set splittable registers. */
2662 find_splittable_givs (loop
, bl
, unroll_type
, increment
, unroll_number
)
2663 const struct loop
*loop
;
2664 struct iv_class
*bl
;
2665 enum unroll_types unroll_type
;
2667 int unroll_number ATTRIBUTE_UNUSED
;
2669 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
2670 struct induction
*v
, *v2
;
2675 /* Scan the list of givs, and set the same_insn field when there are
2676 multiple identical givs in the same insn. */
2677 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2678 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2679 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2683 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2687 /* Only split the giv if it has already been reduced, or if the loop is
2688 being completely unrolled. */
2689 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2692 /* The giv can be split if the insn that sets the giv is executed once
2693 and only once on every iteration of the loop. */
2694 /* An address giv can always be split. v->insn is just a use not a set,
2695 and hence it does not matter whether it is always executed. All that
2696 matters is that all the biv increments are always executed, and we
2697 won't reach here if they aren't. */
2698 if (v
->giv_type
!= DEST_ADDR
2699 && (! v
->always_computable
2700 || back_branch_in_range_p (loop
, v
->insn
)))
2703 /* The giv increment value must be a constant. */
2704 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2706 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2709 /* The loop must be unrolled completely, or else have a known number of
2710 iterations and only one exit, or else the giv must be dead outside
2711 the loop, or else the final value of the giv must be known.
2712 Otherwise, it is not safe to split the giv since it may not have the
2713 proper value on loop exit. */
2715 /* The used outside loop test will fail for DEST_ADDR givs. They are
2716 never used outside the loop anyways, so it is always safe to split a
2720 if (unroll_type
!= UNROLL_COMPLETELY
2721 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2722 && v
->giv_type
!= DEST_ADDR
2723 /* The next part is true if the pseudo is used outside the loop.
2724 We assume that this is true for any pseudo created after loop
2725 starts, because we don't have a reg_n_info entry for them. */
2726 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2727 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2728 /* Check for the case where the pseudo is set by a shift/add
2729 sequence, in which case the first insn setting the pseudo
2730 is the first insn of the shift/add sequence. */
2731 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2732 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2733 != INSN_UID (XEXP (tem
, 0)))))
2734 /* Line above always fails if INSN was moved by loop opt. */
2735 || (REGNO_LAST_LUID (REGNO (v
->dest_reg
))
2736 >= INSN_LUID (loop
->end
)))
2737 && ! (final_value
= v
->final_value
))
2741 /* Currently, non-reduced/final-value givs are never split. */
2742 /* Should emit insns after the loop if possible, as the biv final value
2745 /* If the final value is nonzero, and the giv has not been reduced,
2746 then must emit an instruction to set the final value. */
2747 if (final_value
&& !v
->new_reg
)
2749 /* Create a new register to hold the value of the giv, and then set
2750 the giv to its final value before the loop start. The giv is set
2751 to its final value before loop start to ensure that this insn
2752 will always be executed, no matter how we exit. */
2753 tem
= gen_reg_rtx (v
->mode
);
2754 loop_insn_hoist (loop
, gen_move_insn (tem
, v
->dest_reg
));
2755 loop_insn_hoist (loop
, gen_move_insn (v
->dest_reg
, final_value
));
2757 if (loop_dump_stream
)
2758 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2759 REGNO (v
->dest_reg
), REGNO (tem
));
2765 /* This giv is splittable. If completely unrolling the loop, save the
2766 giv's initial value. Otherwise, save the constant zero for it. */
2768 if (unroll_type
== UNROLL_COMPLETELY
)
2770 /* It is not safe to use bl->initial_value here, because it may not
2771 be invariant. It is safe to use the initial value stored in
2772 the splittable_regs array if it is set. In rare cases, it won't
2773 be set, so then we do exactly the same thing as
2774 find_splittable_regs does to get a safe value. */
2775 rtx biv_initial_value
;
2777 if (splittable_regs
[bl
->regno
])
2778 biv_initial_value
= splittable_regs
[bl
->regno
];
2779 else if (GET_CODE (bl
->initial_value
) != REG
2780 || (REGNO (bl
->initial_value
) != bl
->regno
2781 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2782 biv_initial_value
= bl
->initial_value
;
2785 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2787 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2788 loop_insn_hoist (loop
, gen_move_insn (tem
, bl
->biv
->src_reg
));
2789 biv_initial_value
= tem
;
2791 biv_initial_value
= extend_value_for_giv (v
, biv_initial_value
);
2792 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2793 v
->add_val
, v
->mode
);
2800 /* If a giv was combined with another giv, then we can only split
2801 this giv if the giv it was combined with was reduced. This
2802 is because the value of v->new_reg is meaningless in this
2804 if (v
->same
&& ! v
->same
->new_reg
)
2806 if (loop_dump_stream
)
2807 fprintf (loop_dump_stream
,
2808 "giv combined with unreduced giv not split.\n");
2811 /* If the giv is an address destination, it could be something other
2812 than a simple register, these have to be treated differently. */
2813 else if (v
->giv_type
== DEST_REG
)
2815 /* If value is not a constant, register, or register plus
2816 constant, then compute its value into a register before
2817 loop start. This prevents invalid rtx sharing, and should
2818 generate better code. We can use bl->initial_value here
2819 instead of splittable_regs[bl->regno] because this code
2820 is going before the loop start. */
2821 if (unroll_type
== UNROLL_COMPLETELY
2822 && GET_CODE (value
) != CONST_INT
2823 && GET_CODE (value
) != REG
2824 && (GET_CODE (value
) != PLUS
2825 || GET_CODE (XEXP (value
, 0)) != REG
2826 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2828 rtx tem
= gen_reg_rtx (v
->mode
);
2829 record_base_value (REGNO (tem
), v
->add_val
, 0);
2830 loop_iv_add_mult_hoist (loop
, bl
->initial_value
, v
->mult_val
,
2835 splittable_regs
[reg_or_subregno (v
->new_reg
)] = value
;
2843 /* Currently, unreduced giv's can't be split. This is not too much
2844 of a problem since unreduced giv's are not live across loop
2845 iterations anyways. When unrolling a loop completely though,
2846 it makes sense to reduce&split givs when possible, as this will
2847 result in simpler instructions, and will not require that a reg
2848 be live across loop iterations. */
2850 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
2851 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
2852 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
2858 /* Unreduced givs are only updated once by definition. Reduced givs
2859 are updated as many times as their biv is. Mark it so if this is
2860 a splittable register. Don't need to do anything for address givs
2861 where this may not be a register. */
2863 if (GET_CODE (v
->new_reg
) == REG
)
2867 count
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
))->biv_count
;
2869 splittable_regs_updates
[reg_or_subregno (v
->new_reg
)] = count
;
2874 if (loop_dump_stream
)
2878 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
2880 else if (GET_CODE (v
->dest_reg
) != REG
)
2881 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
2883 regnum
= REGNO (v
->dest_reg
);
2884 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
2885 regnum
, INSN_UID (v
->insn
));
2892 /* Try to prove that the register is dead after the loop exits. Trace every
2893 loop exit looking for an insn that will always be executed, which sets
2894 the register to some value, and appears before the first use of the register
2895 is found. If successful, then return 1, otherwise return 0. */
2897 /* ?? Could be made more intelligent in the handling of jumps, so that
2898 it can search past if statements and other similar structures. */
2901 reg_dead_after_loop (loop
, reg
)
2902 const struct loop
*loop
;
2908 int label_count
= 0;
2910 /* In addition to checking all exits of this loop, we must also check
2911 all exits of inner nested loops that would exit this loop. We don't
2912 have any way to identify those, so we just give up if there are any
2913 such inner loop exits. */
2915 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
2918 if (label_count
!= loop
->exit_count
)
2921 /* HACK: Must also search the loop fall through exit, create a label_ref
2922 here which points to the loop->end, and append the loop_number_exit_labels
2924 label
= gen_rtx_LABEL_REF (VOIDmode
, loop
->end
);
2925 LABEL_NEXTREF (label
) = loop
->exit_labels
;
2927 for (; label
; label
= LABEL_NEXTREF (label
))
2929 /* Succeed if find an insn which sets the biv or if reach end of
2930 function. Fail if find an insn that uses the biv, or if come to
2931 a conditional jump. */
2933 insn
= NEXT_INSN (XEXP (label
, 0));
2936 code
= GET_CODE (insn
);
2937 if (GET_RTX_CLASS (code
) == 'i')
2941 if (reg_referenced_p (reg
, PATTERN (insn
)))
2944 set
= single_set (insn
);
2945 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
2949 if (code
== JUMP_INSN
)
2951 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2953 else if (!any_uncondjump_p (insn
)
2954 /* Prevent infinite loop following infinite loops. */
2955 || jump_count
++ > 20)
2958 insn
= JUMP_LABEL (insn
);
2961 insn
= NEXT_INSN (insn
);
2965 /* Success, the register is dead on all loop exits. */
2969 /* Try to calculate the final value of the biv, the value it will have at
2970 the end of the loop. If we can do it, return that value. */
2973 final_biv_value (loop
, bl
)
2974 const struct loop
*loop
;
2975 struct iv_class
*bl
;
2977 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
2980 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
2982 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
2985 /* The final value for reversed bivs must be calculated differently than
2986 for ordinary bivs. In this case, there is already an insn after the
2987 loop which sets this biv's final value (if necessary), and there are
2988 no other loop exits, so we can return any value. */
2991 if (loop_dump_stream
)
2992 fprintf (loop_dump_stream
,
2993 "Final biv value for %d, reversed biv.\n", bl
->regno
);
2998 /* Try to calculate the final value as initial value + (number of iterations
2999 * increment). For this to work, increment must be invariant, the only
3000 exit from the loop must be the fall through at the bottom (otherwise
3001 it may not have its final value when the loop exits), and the initial
3002 value of the biv must be invariant. */
3004 if (n_iterations
!= 0
3005 && ! loop
->exit_count
3006 && loop_invariant_p (loop
, bl
->initial_value
))
3008 increment
= biv_total_increment (bl
);
3010 if (increment
&& loop_invariant_p (loop
, increment
))
3012 /* Can calculate the loop exit value, emit insns after loop
3013 end to calculate this value into a temporary register in
3014 case it is needed later. */
3016 tem
= gen_reg_rtx (bl
->biv
->mode
);
3017 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3018 loop_iv_add_mult_sink (loop
, increment
, GEN_INT (n_iterations
),
3019 bl
->initial_value
, tem
);
3021 if (loop_dump_stream
)
3022 fprintf (loop_dump_stream
,
3023 "Final biv value for %d, calculated.\n", bl
->regno
);
3029 /* Check to see if the biv is dead at all loop exits. */
3030 if (reg_dead_after_loop (loop
, bl
->biv
->src_reg
))
3032 if (loop_dump_stream
)
3033 fprintf (loop_dump_stream
,
3034 "Final biv value for %d, biv dead after loop exit.\n",
3043 /* Try to calculate the final value of the giv, the value it will have at
3044 the end of the loop. If we can do it, return that value. */
3047 final_giv_value (loop
, v
)
3048 const struct loop
*loop
;
3049 struct induction
*v
;
3051 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3052 struct iv_class
*bl
;
3056 rtx loop_end
= loop
->end
;
3057 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3059 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
3061 /* The final value for givs which depend on reversed bivs must be calculated
3062 differently than for ordinary givs. In this case, there is already an
3063 insn after the loop which sets this giv's final value (if necessary),
3064 and there are no other loop exits, so we can return any value. */
3067 if (loop_dump_stream
)
3068 fprintf (loop_dump_stream
,
3069 "Final giv value for %d, depends on reversed biv\n",
3070 REGNO (v
->dest_reg
));
3074 /* Try to calculate the final value as a function of the biv it depends
3075 upon. The only exit from the loop must be the fall through at the bottom
3076 and the insn that sets the giv must be executed on every iteration
3077 (otherwise the giv may not have its final value when the loop exits). */
3079 /* ??? Can calculate the final giv value by subtracting off the
3080 extra biv increments times the giv's mult_val. The loop must have
3081 only one exit for this to work, but the loop iterations does not need
3084 if (n_iterations
!= 0
3085 && ! loop
->exit_count
3086 && v
->always_executed
)
3088 /* ?? It is tempting to use the biv's value here since these insns will
3089 be put after the loop, and hence the biv will have its final value
3090 then. However, this fails if the biv is subsequently eliminated.
3091 Perhaps determine whether biv's are eliminable before trying to
3092 determine whether giv's are replaceable so that we can use the
3093 biv value here if it is not eliminable. */
3095 /* We are emitting code after the end of the loop, so we must make
3096 sure that bl->initial_value is still valid then. It will still
3097 be valid if it is invariant. */
3099 increment
= biv_total_increment (bl
);
3101 if (increment
&& loop_invariant_p (loop
, increment
)
3102 && loop_invariant_p (loop
, bl
->initial_value
))
3104 /* Can calculate the loop exit value of its biv as
3105 (n_iterations * increment) + initial_value */
3107 /* The loop exit value of the giv is then
3108 (final_biv_value - extra increments) * mult_val + add_val.
3109 The extra increments are any increments to the biv which
3110 occur in the loop after the giv's value is calculated.
3111 We must search from the insn that sets the giv to the end
3112 of the loop to calculate this value. */
3114 /* Put the final biv value in tem. */
3115 tem
= gen_reg_rtx (v
->mode
);
3116 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3117 loop_iv_add_mult_sink (loop
, extend_value_for_giv (v
, increment
),
3118 GEN_INT (n_iterations
),
3119 extend_value_for_giv (v
, bl
->initial_value
),
3122 /* Subtract off extra increments as we find them. */
3123 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3124 insn
= NEXT_INSN (insn
))
3126 struct induction
*biv
;
3128 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3129 if (biv
->insn
== insn
)
3132 tem
= expand_simple_binop (GET_MODE (tem
), MINUS
, tem
,
3133 biv
->add_val
, NULL_RTX
, 0,
3137 loop_insn_sink (loop
, seq
);
3141 /* Now calculate the giv's final value. */
3142 loop_iv_add_mult_sink (loop
, tem
, v
->mult_val
, v
->add_val
, tem
);
3144 if (loop_dump_stream
)
3145 fprintf (loop_dump_stream
,
3146 "Final giv value for %d, calc from biv's value.\n",
3147 REGNO (v
->dest_reg
));
3153 /* Replaceable giv's should never reach here. */
3157 /* Check to see if the biv is dead at all loop exits. */
3158 if (reg_dead_after_loop (loop
, v
->dest_reg
))
3160 if (loop_dump_stream
)
3161 fprintf (loop_dump_stream
,
3162 "Final giv value for %d, giv dead after loop exit.\n",
3163 REGNO (v
->dest_reg
));
3171 /* Look back before LOOP->START for the insn that sets REG and return
3172 the equivalent constant if there is a REG_EQUAL note otherwise just
3173 the SET_SRC of REG. */
3176 loop_find_equiv_value (loop
, reg
)
3177 const struct loop
*loop
;
3180 rtx loop_start
= loop
->start
;
3185 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3187 if (GET_CODE (insn
) == CODE_LABEL
)
3190 else if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3192 /* We found the last insn before the loop that sets the register.
3193 If it sets the entire register, and has a REG_EQUAL note,
3194 then use the value of the REG_EQUAL note. */
3195 if ((set
= single_set (insn
))
3196 && (SET_DEST (set
) == reg
))
3198 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3200 /* Only use the REG_EQUAL note if it is a constant.
3201 Other things, divide in particular, will cause
3202 problems later if we use them. */
3203 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3204 && CONSTANT_P (XEXP (note
, 0)))
3205 ret
= XEXP (note
, 0);
3207 ret
= SET_SRC (set
);
3209 /* We cannot do this if it changes between the
3210 assignment and loop start though. */
3211 if (modified_between_p (ret
, insn
, loop_start
))
3220 /* Return a simplified rtx for the expression OP - REG.
3222 REG must appear in OP, and OP must be a register or the sum of a register
3225 Thus, the return value must be const0_rtx or the second term.
3227 The caller is responsible for verifying that REG appears in OP and OP has
3231 subtract_reg_term (op
, reg
)
3236 if (GET_CODE (op
) == PLUS
)
3238 if (XEXP (op
, 0) == reg
)
3239 return XEXP (op
, 1);
3240 else if (XEXP (op
, 1) == reg
)
3241 return XEXP (op
, 0);
3243 /* OP does not contain REG as a term. */
3247 /* Find and return register term common to both expressions OP0 and
3248 OP1 or NULL_RTX if no such term exists. Each expression must be a
3249 REG or a PLUS of a REG. */
3252 find_common_reg_term (op0
, op1
)
3255 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3256 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3263 if (GET_CODE (op0
) == PLUS
)
3264 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3266 op01
= const0_rtx
, op00
= op0
;
3268 if (GET_CODE (op1
) == PLUS
)
3269 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3271 op11
= const0_rtx
, op10
= op1
;
3273 /* Find and return common register term if present. */
3274 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3276 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3280 /* No common register term found. */
3284 /* Determine the loop iterator and calculate the number of loop
3285 iterations. Returns the exact number of loop iterations if it can
3286 be calculated, otherwise returns zero. */
3288 unsigned HOST_WIDE_INT
3289 loop_iterations (loop
)
3292 struct loop_info
*loop_info
= LOOP_INFO (loop
);
3293 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3294 rtx comparison
, comparison_value
;
3295 rtx iteration_var
, initial_value
, increment
, final_value
;
3296 enum rtx_code comparison_code
;
3298 unsigned HOST_WIDE_INT abs_inc
;
3299 unsigned HOST_WIDE_INT abs_diff
;
3302 int unsigned_p
, compare_dir
, final_larger
;
3305 struct iv_class
*bl
;
3307 loop_info
->n_iterations
= 0;
3308 loop_info
->initial_value
= 0;
3309 loop_info
->initial_equiv_value
= 0;
3310 loop_info
->comparison_value
= 0;
3311 loop_info
->final_value
= 0;
3312 loop_info
->final_equiv_value
= 0;
3313 loop_info
->increment
= 0;
3314 loop_info
->iteration_var
= 0;
3315 loop_info
->unroll_number
= 1;
3318 /* We used to use prev_nonnote_insn here, but that fails because it might
3319 accidentally get the branch for a contained loop if the branch for this
3320 loop was deleted. We can only trust branches immediately before the
3322 last_loop_insn
= PREV_INSN (loop
->end
);
3324 /* ??? We should probably try harder to find the jump insn
3325 at the end of the loop. The following code assumes that
3326 the last loop insn is a jump to the top of the loop. */
3327 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3329 if (loop_dump_stream
)
3330 fprintf (loop_dump_stream
,
3331 "Loop iterations: No final conditional branch found.\n");
3335 /* If there is a more than a single jump to the top of the loop
3336 we cannot (easily) determine the iteration count. */
3337 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3339 if (loop_dump_stream
)
3340 fprintf (loop_dump_stream
,
3341 "Loop iterations: Loop has multiple back edges.\n");
3345 /* If there are multiple conditionalized loop exit tests, they may jump
3346 back to differing CODE_LABELs. */
3347 if (loop
->top
&& loop
->cont
)
3349 rtx temp
= PREV_INSN (last_loop_insn
);
3353 if (GET_CODE (temp
) == JUMP_INSN
)
3355 /* There are some kinds of jumps we can't deal with easily. */
3356 if (JUMP_LABEL (temp
) == 0)
3358 if (loop_dump_stream
)
3361 "Loop iterations: Jump insn has null JUMP_LABEL.\n");
3365 if (/* Previous unrolling may have generated new insns not
3366 covered by the uid_luid array. */
3367 INSN_UID (JUMP_LABEL (temp
)) < max_uid_for_loop
3368 /* Check if we jump back into the loop body. */
3369 && INSN_LUID (JUMP_LABEL (temp
)) > INSN_LUID (loop
->top
)
3370 && INSN_LUID (JUMP_LABEL (temp
)) < INSN_LUID (loop
->cont
))
3372 if (loop_dump_stream
)
3375 "Loop iterations: Loop has multiple back edges.\n");
3380 while ((temp
= PREV_INSN (temp
)) != loop
->cont
);
3383 /* Find the iteration variable. If the last insn is a conditional
3384 branch, and the insn before tests a register value, make that the
3385 iteration variable. */
3387 comparison
= get_condition_for_loop (loop
, last_loop_insn
);
3388 if (comparison
== 0)
3390 if (loop_dump_stream
)
3391 fprintf (loop_dump_stream
,
3392 "Loop iterations: No final comparison found.\n");
3396 /* ??? Get_condition may switch position of induction variable and
3397 invariant register when it canonicalizes the comparison. */
3399 comparison_code
= GET_CODE (comparison
);
3400 iteration_var
= XEXP (comparison
, 0);
3401 comparison_value
= XEXP (comparison
, 1);
3403 if (GET_CODE (iteration_var
) != REG
)
3405 if (loop_dump_stream
)
3406 fprintf (loop_dump_stream
,
3407 "Loop iterations: Comparison not against register.\n");
3411 /* The only new registers that are created before loop iterations
3412 are givs made from biv increments or registers created by
3413 load_mems. In the latter case, it is possible that try_copy_prop
3414 will propagate a new pseudo into the old iteration register but
3415 this will be marked by having the REG_USERVAR_P bit set. */
3417 if ((unsigned) REGNO (iteration_var
) >= ivs
->n_regs
3418 && ! REG_USERVAR_P (iteration_var
))
3421 /* Determine the initial value of the iteration variable, and the amount
3422 that it is incremented each loop. Use the tables constructed by
3423 the strength reduction pass to calculate these values. */
3425 /* Clear the result values, in case no answer can be found. */
3429 /* The iteration variable can be either a giv or a biv. Check to see
3430 which it is, and compute the variable's initial value, and increment
3431 value if possible. */
3433 /* If this is a new register, can't handle it since we don't have any
3434 reg_iv_type entry for it. */
3435 if ((unsigned) REGNO (iteration_var
) >= ivs
->n_regs
)
3437 if (loop_dump_stream
)
3438 fprintf (loop_dump_stream
,
3439 "Loop iterations: No reg_iv_type entry for iteration var.\n");
3443 /* Reject iteration variables larger than the host wide int size, since they
3444 could result in a number of iterations greater than the range of our
3445 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
3446 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
3447 > HOST_BITS_PER_WIDE_INT
))
3449 if (loop_dump_stream
)
3450 fprintf (loop_dump_stream
,
3451 "Loop iterations: Iteration var rejected because mode too large.\n");
3454 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
3456 if (loop_dump_stream
)
3457 fprintf (loop_dump_stream
,
3458 "Loop iterations: Iteration var not an integer.\n");
3461 else if (REG_IV_TYPE (ivs
, REGNO (iteration_var
)) == BASIC_INDUCT
)
3463 if (REGNO (iteration_var
) >= ivs
->n_regs
)
3466 /* Grab initial value, only useful if it is a constant. */
3467 bl
= REG_IV_CLASS (ivs
, REGNO (iteration_var
));
3468 initial_value
= bl
->initial_value
;
3469 if (!bl
->biv
->always_executed
|| bl
->biv
->maybe_multiple
)
3471 if (loop_dump_stream
)
3472 fprintf (loop_dump_stream
,
3473 "Loop iterations: Basic induction var not set once in each iteration.\n");
3477 increment
= biv_total_increment (bl
);
3479 else if (REG_IV_TYPE (ivs
, REGNO (iteration_var
)) == GENERAL_INDUCT
)
3481 HOST_WIDE_INT offset
= 0;
3482 struct induction
*v
= REG_IV_INFO (ivs
, REGNO (iteration_var
));
3483 rtx biv_initial_value
;
3485 if (REGNO (v
->src_reg
) >= ivs
->n_regs
)
3488 if (!v
->always_executed
|| v
->maybe_multiple
)
3490 if (loop_dump_stream
)
3491 fprintf (loop_dump_stream
,
3492 "Loop iterations: General induction var not set once in each iteration.\n");
3496 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
3498 /* Increment value is mult_val times the increment value of the biv. */
3500 increment
= biv_total_increment (bl
);
3503 struct induction
*biv_inc
;
3505 increment
= fold_rtx_mult_add (v
->mult_val
,
3506 extend_value_for_giv (v
, increment
),
3507 const0_rtx
, v
->mode
);
3508 /* The caller assumes that one full increment has occurred at the
3509 first loop test. But that's not true when the biv is incremented
3510 after the giv is set (which is the usual case), e.g.:
3511 i = 6; do {;} while (i++ < 9) .
3512 Therefore, we bias the initial value by subtracting the amount of
3513 the increment that occurs between the giv set and the giv test. */
3514 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
3516 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
3518 if (REG_P (biv_inc
->add_val
))
3520 if (loop_dump_stream
)
3521 fprintf (loop_dump_stream
,
3522 "Loop iterations: Basic induction var add_val is REG %d.\n",
3523 REGNO (biv_inc
->add_val
));
3527 offset
-= INTVAL (biv_inc
->add_val
);
3531 if (loop_dump_stream
)
3532 fprintf (loop_dump_stream
,
3533 "Loop iterations: Giv iterator, initial value bias %ld.\n",
3536 /* Initial value is mult_val times the biv's initial value plus
3537 add_val. Only useful if it is a constant. */
3538 biv_initial_value
= extend_value_for_giv (v
, bl
->initial_value
);
3540 = fold_rtx_mult_add (v
->mult_val
,
3541 plus_constant (biv_initial_value
, offset
),
3542 v
->add_val
, v
->mode
);
3546 if (loop_dump_stream
)
3547 fprintf (loop_dump_stream
,
3548 "Loop iterations: Not basic or general induction var.\n");
3552 if (initial_value
== 0)
3557 switch (comparison_code
)
3572 /* Cannot determine loop iterations with this case. */
3591 /* If the comparison value is an invariant register, then try to find
3592 its value from the insns before the start of the loop. */
3594 final_value
= comparison_value
;
3595 if (GET_CODE (comparison_value
) == REG
3596 && loop_invariant_p (loop
, comparison_value
))
3598 final_value
= loop_find_equiv_value (loop
, comparison_value
);
3600 /* If we don't get an invariant final value, we are better
3601 off with the original register. */
3602 if (! loop_invariant_p (loop
, final_value
))
3603 final_value
= comparison_value
;
3606 /* Calculate the approximate final value of the induction variable
3607 (on the last successful iteration). The exact final value
3608 depends on the branch operator, and increment sign. It will be
3609 wrong if the iteration variable is not incremented by one each
3610 time through the loop and (comparison_value + off_by_one -
3611 initial_value) % increment != 0.
3612 ??? Note that the final_value may overflow and thus final_larger
3613 will be bogus. A potentially infinite loop will be classified
3614 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3616 final_value
= plus_constant (final_value
, off_by_one
);
3618 /* Save the calculated values describing this loop's bounds, in case
3619 precondition_loop_p will need them later. These values can not be
3620 recalculated inside precondition_loop_p because strength reduction
3621 optimizations may obscure the loop's structure.
3623 These values are only required by precondition_loop_p and insert_bct
3624 whenever the number of iterations cannot be computed at compile time.
3625 Only the difference between final_value and initial_value is
3626 important. Note that final_value is only approximate. */
3627 loop_info
->initial_value
= initial_value
;
3628 loop_info
->comparison_value
= comparison_value
;
3629 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3630 loop_info
->increment
= increment
;
3631 loop_info
->iteration_var
= iteration_var
;
3632 loop_info
->comparison_code
= comparison_code
;
3635 /* Try to determine the iteration count for loops such
3636 as (for i = init; i < init + const; i++). When running the
3637 loop optimization twice, the first pass often converts simple
3638 loops into this form. */
3640 if (REG_P (initial_value
))
3646 reg1
= initial_value
;
3647 if (GET_CODE (final_value
) == PLUS
)
3648 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3650 reg2
= final_value
, const2
= const0_rtx
;
3652 /* Check for initial_value = reg1, final_value = reg2 + const2,
3653 where reg1 != reg2. */
3654 if (REG_P (reg2
) && reg2
!= reg1
)
3658 /* Find what reg1 is equivalent to. Hopefully it will
3659 either be reg2 or reg2 plus a constant. */
3660 temp
= loop_find_equiv_value (loop
, reg1
);
3662 if (find_common_reg_term (temp
, reg2
))
3663 initial_value
= temp
;
3666 /* Find what reg2 is equivalent to. Hopefully it will
3667 either be reg1 or reg1 plus a constant. Let's ignore
3668 the latter case for now since it is not so common. */
3669 temp
= loop_find_equiv_value (loop
, reg2
);
3671 if (temp
== loop_info
->iteration_var
)
3672 temp
= initial_value
;
3674 final_value
= (const2
== const0_rtx
)
3675 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3678 else if (loop
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3682 /* When running the loop optimizer twice, check_dbra_loop
3683 further obfuscates reversible loops of the form:
3684 for (i = init; i < init + const; i++). We often end up with
3685 final_value = 0, initial_value = temp, temp = temp2 - init,
3686 where temp2 = init + const. If the loop has a vtop we
3687 can replace initial_value with const. */
3689 temp
= loop_find_equiv_value (loop
, reg1
);
3691 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3693 rtx temp2
= loop_find_equiv_value (loop
, XEXP (temp
, 0));
3695 if (GET_CODE (temp2
) == PLUS
3696 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3697 initial_value
= XEXP (temp2
, 1);
3702 /* If have initial_value = reg + const1 and final_value = reg +
3703 const2, then replace initial_value with const1 and final_value
3704 with const2. This should be safe since we are protected by the
3705 initial comparison before entering the loop if we have a vtop.
3706 For example, a + b < a + c is not equivalent to b < c for all a
3707 when using modulo arithmetic.
3709 ??? Without a vtop we could still perform the optimization if we check
3710 the initial and final values carefully. */
3712 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3714 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3715 final_value
= subtract_reg_term (final_value
, reg_term
);
3718 loop_info
->initial_equiv_value
= initial_value
;
3719 loop_info
->final_equiv_value
= final_value
;
3721 /* For EQ comparison loops, we don't have a valid final value.
3722 Check this now so that we won't leave an invalid value if we
3723 return early for any other reason. */
3724 if (comparison_code
== EQ
)
3725 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3729 if (loop_dump_stream
)
3730 fprintf (loop_dump_stream
,
3731 "Loop iterations: Increment value can't be calculated.\n");
3735 if (GET_CODE (increment
) != CONST_INT
)
3737 /* If we have a REG, check to see if REG holds a constant value. */
3738 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3739 clear if it is worthwhile to try to handle such RTL. */
3740 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3741 increment
= loop_find_equiv_value (loop
, increment
);
3743 if (GET_CODE (increment
) != CONST_INT
)
3745 if (loop_dump_stream
)
3747 fprintf (loop_dump_stream
,
3748 "Loop iterations: Increment value not constant ");
3749 print_simple_rtl (loop_dump_stream
, increment
);
3750 fprintf (loop_dump_stream
, ".\n");
3754 loop_info
->increment
= increment
;
3757 if (GET_CODE (initial_value
) != CONST_INT
)
3759 if (loop_dump_stream
)
3761 fprintf (loop_dump_stream
,
3762 "Loop iterations: Initial value not constant ");
3763 print_simple_rtl (loop_dump_stream
, initial_value
);
3764 fprintf (loop_dump_stream
, ".\n");
3768 else if (GET_CODE (final_value
) != CONST_INT
)
3770 if (loop_dump_stream
)
3772 fprintf (loop_dump_stream
,
3773 "Loop iterations: Final value not constant ");
3774 print_simple_rtl (loop_dump_stream
, final_value
);
3775 fprintf (loop_dump_stream
, ".\n");
3779 else if (comparison_code
== EQ
)
3783 if (loop_dump_stream
)
3784 fprintf (loop_dump_stream
, "Loop iterations: EQ comparison loop.\n");
3786 inc_once
= gen_int_mode (INTVAL (initial_value
) + INTVAL (increment
),
3787 GET_MODE (iteration_var
));
3789 if (inc_once
== final_value
)
3791 /* The iterator value once through the loop is equal to the
3792 comparision value. Either we have an infinite loop, or
3793 we'll loop twice. */
3794 if (increment
== const0_rtx
)
3796 loop_info
->n_iterations
= 2;
3799 loop_info
->n_iterations
= 1;
3801 if (GET_CODE (loop_info
->initial_value
) == CONST_INT
)
3802 loop_info
->final_value
3803 = gen_int_mode ((INTVAL (loop_info
->initial_value
)
3804 + loop_info
->n_iterations
* INTVAL (increment
)),
3805 GET_MODE (iteration_var
));
3807 loop_info
->final_value
3808 = plus_constant (loop_info
->initial_value
,
3809 loop_info
->n_iterations
* INTVAL (increment
));
3810 loop_info
->final_equiv_value
3811 = gen_int_mode ((INTVAL (initial_value
)
3812 + loop_info
->n_iterations
* INTVAL (increment
)),
3813 GET_MODE (iteration_var
));
3814 return loop_info
->n_iterations
;
3817 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3820 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3821 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3822 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3823 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3825 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3826 - (INTVAL (final_value
) < INTVAL (initial_value
));
3828 if (INTVAL (increment
) > 0)
3830 else if (INTVAL (increment
) == 0)
3835 /* There are 27 different cases: compare_dir = -1, 0, 1;
3836 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3837 There are 4 normal cases, 4 reverse cases (where the iteration variable
3838 will overflow before the loop exits), 4 infinite loop cases, and 15
3839 immediate exit (0 or 1 iteration depending on loop type) cases.
3840 Only try to optimize the normal cases. */
3842 /* (compare_dir/final_larger/increment_dir)
3843 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3844 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3845 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3846 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3848 /* ?? If the meaning of reverse loops (where the iteration variable
3849 will overflow before the loop exits) is undefined, then could
3850 eliminate all of these special checks, and just always assume
3851 the loops are normal/immediate/infinite. Note that this means
3852 the sign of increment_dir does not have to be known. Also,
3853 since it does not really hurt if immediate exit loops or infinite loops
3854 are optimized, then that case could be ignored also, and hence all
3855 loops can be optimized.
3857 According to ANSI Spec, the reverse loop case result is undefined,
3858 because the action on overflow is undefined.
3860 See also the special test for NE loops below. */
3862 if (final_larger
== increment_dir
&& final_larger
!= 0
3863 && (final_larger
== compare_dir
|| compare_dir
== 0))
3868 if (loop_dump_stream
)
3869 fprintf (loop_dump_stream
, "Loop iterations: Not normal loop.\n");
3873 /* Calculate the number of iterations, final_value is only an approximation,
3874 so correct for that. Note that abs_diff and n_iterations are
3875 unsigned, because they can be as large as 2^n - 1. */
3877 inc
= INTVAL (increment
);
3880 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
3885 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
3891 /* Given that iteration_var is going to iterate over its own mode,
3892 not HOST_WIDE_INT, disregard higher bits that might have come
3893 into the picture due to sign extension of initial and final
3895 abs_diff
&= ((unsigned HOST_WIDE_INT
) 1
3896 << (GET_MODE_BITSIZE (GET_MODE (iteration_var
)) - 1)
3899 /* For NE tests, make sure that the iteration variable won't miss
3900 the final value. If abs_diff mod abs_incr is not zero, then the
3901 iteration variable will overflow before the loop exits, and we
3902 can not calculate the number of iterations. */
3903 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
3906 /* Note that the number of iterations could be calculated using
3907 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3908 handle potential overflow of the summation. */
3909 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
3910 return loop_info
->n_iterations
;
3913 /* Replace uses of split bivs with their split pseudo register. This is
3914 for original instructions which remain after loop unrolling without
3918 remap_split_bivs (loop
, x
)
3922 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3930 code
= GET_CODE (x
);
3945 /* If non-reduced/final-value givs were split, then this would also
3946 have to remap those givs also. */
3948 if (REGNO (x
) < ivs
->n_regs
3949 && REG_IV_TYPE (ivs
, REGNO (x
)) == BASIC_INDUCT
)
3950 return REG_IV_CLASS (ivs
, REGNO (x
))->biv
->src_reg
;
3957 fmt
= GET_RTX_FORMAT (code
);
3958 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3961 XEXP (x
, i
) = remap_split_bivs (loop
, XEXP (x
, i
));
3962 else if (fmt
[i
] == 'E')
3965 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3966 XVECEXP (x
, i
, j
) = remap_split_bivs (loop
, XVECEXP (x
, i
, j
));
3972 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3973 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3974 return 0. COPY_START is where we can start looking for the insns
3975 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3978 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3979 must dominate LAST_UID.
3981 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3982 may not dominate LAST_UID.
3984 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3985 must dominate LAST_UID. */
3988 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
3995 int passed_jump
= 0;
3996 rtx p
= NEXT_INSN (copy_start
);
3998 while (INSN_UID (p
) != first_uid
)
4000 if (GET_CODE (p
) == JUMP_INSN
)
4002 /* Could not find FIRST_UID. */
4008 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4009 if (! INSN_P (p
) || ! dead_or_set_regno_p (p
, regno
))
4012 /* FIRST_UID is always executed. */
4013 if (passed_jump
== 0)
4016 while (INSN_UID (p
) != last_uid
)
4018 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4019 can not be sure that FIRST_UID dominates LAST_UID. */
4020 if (GET_CODE (p
) == CODE_LABEL
)
4022 /* Could not find LAST_UID, but we reached the end of the loop, so
4024 else if (p
== copy_end
)
4029 /* FIRST_UID is always executed if LAST_UID is executed. */
4033 /* This routine is called when the number of iterations for the unrolled
4034 loop is one. The goal is to identify a loop that begins with an
4035 unconditional branch to the loop continuation note (or a label just after).
4036 In this case, the unconditional branch that starts the loop needs to be
4037 deleted so that we execute the single iteration. */
4040 ujump_to_loop_cont (loop_start
, loop_cont
)
4044 rtx x
, label
, label_ref
;
4046 /* See if loop start, or the next insn is an unconditional jump. */
4047 loop_start
= next_nonnote_insn (loop_start
);
4049 x
= pc_set (loop_start
);
4053 label_ref
= SET_SRC (x
);
4057 /* Examine insn after loop continuation note. Return if not a label. */
4058 label
= next_nonnote_insn (loop_cont
);
4059 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
4062 /* Return the loop start if the branch label matches the code label. */
4063 if (CODE_LABEL_NUMBER (label
) == CODE_LABEL_NUMBER (XEXP (label_ref
, 0)))