1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
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. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor
{ int factor
, count
; } factors
[NUM_FACTORS
]
144 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
148 enum unroll_types
{ UNROLL_COMPLETELY
, UNROLL_MODULO
, UNROLL_NAIVE
};
154 #include "insn-config.h"
155 #include "integrate.h"
159 #include "function.h"
164 /* This controls which loops are unrolled, and by how much we unroll
167 #ifndef MAX_UNROLLED_INSNS
168 #define MAX_UNROLLED_INSNS 100
171 /* Indexed by register number, if non-zero, then it contains a pointer
172 to a struct induction for a DEST_REG giv which has been combined with
173 one of more address givs. This is needed because whenever such a DEST_REG
174 giv is modified, we must modify the value of all split address givs
175 that were combined with this DEST_REG giv. */
177 static struct induction
**addr_combined_regs
;
179 /* Indexed by register number, if this is a splittable induction variable,
180 then this will hold the current value of the register, which depends on the
183 static rtx
*splittable_regs
;
185 /* Indexed by register number, if this is a splittable induction variable,
186 this indicates if it was made from a derived giv. */
187 static char *derived_regs
;
189 /* Indexed by register number, if this is a splittable induction variable,
190 then this will hold the number of instructions in the loop that modify
191 the induction variable. Used to ensure that only the last insn modifying
192 a split iv will update the original iv of the dest. */
194 static int *splittable_regs_updates
;
196 /* Forward declarations. */
198 static void init_reg_map
PARAMS ((struct inline_remap
*, int));
199 static rtx calculate_giv_inc
PARAMS ((rtx
, rtx
, unsigned int));
200 static rtx initial_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
201 static void final_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
202 static void copy_loop_body
PARAMS ((rtx
, rtx
, struct inline_remap
*, rtx
, int,
203 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
204 static void iteration_info
PARAMS ((const struct loop
*, rtx
, rtx
*, rtx
*));
205 static int find_splittable_regs
PARAMS ((const struct loop
*,
206 enum unroll_types
, rtx
, int));
207 static int find_splittable_givs
PARAMS ((const struct loop
*,
208 struct iv_class
*, enum unroll_types
,
210 static int reg_dead_after_loop
PARAMS ((const struct loop
*, rtx
));
211 static rtx fold_rtx_mult_add
PARAMS ((rtx
, rtx
, rtx
, enum machine_mode
));
212 static int verify_addresses
PARAMS ((struct induction
*, rtx
, int));
213 static rtx remap_split_bivs
PARAMS ((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
));
218 /* Try to unroll one loop and split induction variables in the loop.
220 The loop is described by the arguments LOOP and INSN_COUNT.
221 END_INSERT_BEFORE indicates where insns should be added which need
222 to be executed when the loop falls through. STRENGTH_REDUCTION_P
223 indicates whether information generated in the strength reduction
226 This function is intended to be called from within `strength_reduce'
230 unroll_loop (loop
, insn_count
, end_insert_before
, strength_reduce_p
)
233 rtx end_insert_before
;
234 int strength_reduce_p
;
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
;
262 struct loop_info
*loop_info
= LOOP_INFO (loop
);
264 /* Don't bother unrolling huge loops. Since the minimum factor is
265 two, loops greater than one half of MAX_UNROLLED_INSNS will never
267 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
269 if (loop_dump_stream
)
270 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
274 /* When emitting debugger info, we can't unroll loops with unequal numbers
275 of block_beg and block_end notes, because that would unbalance the block
276 structure of the function. This can happen as a result of the
277 "if (foo) bar; else break;" optimization in jump.c. */
278 /* ??? Gcc has a general policy that -g is never supposed to change the code
279 that the compiler emits, so we must disable this optimization always,
280 even if debug info is not being output. This is rare, so this should
281 not be a significant performance problem. */
283 if (1 /* write_symbols != NO_DEBUG */)
285 int block_begins
= 0;
288 for (insn
= loop_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
290 if (GET_CODE (insn
) == NOTE
)
292 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
)
294 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
296 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_BEG
297 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_END
)
299 /* Note, would be nice to add code to unroll EH
300 regions, but until that time, we punt (don't
301 unroll). For the proper way of doing it, see
302 expand_inline_function. */
304 if (loop_dump_stream
)
305 fprintf (loop_dump_stream
,
306 "Unrolling failure: cannot unroll EH regions.\n");
312 if (block_begins
!= block_ends
)
314 if (loop_dump_stream
)
315 fprintf (loop_dump_stream
,
316 "Unrolling failure: Unbalanced block notes.\n");
321 /* Determine type of unroll to perform. Depends on the number of iterations
322 and the size of the loop. */
324 /* If there is no strength reduce info, then set
325 loop_info->n_iterations to zero. This can happen if
326 strength_reduce can't find any bivs in the loop. A value of zero
327 indicates that the number of iterations could not be calculated. */
329 if (! strength_reduce_p
)
330 loop_info
->n_iterations
= 0;
332 if (loop_dump_stream
&& loop_info
->n_iterations
> 0)
334 fputs ("Loop unrolling: ", loop_dump_stream
);
335 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
336 loop_info
->n_iterations
);
337 fputs (" iterations.\n", loop_dump_stream
);
340 /* Find and save a pointer to the last nonnote insn in the loop. */
342 last_loop_insn
= prev_nonnote_insn (loop_end
);
344 /* Calculate how many times to unroll the loop. Indicate whether or
345 not the loop is being completely unrolled. */
347 if (loop_info
->n_iterations
== 1)
349 /* If number of iterations is exactly 1, then eliminate the compare and
350 branch at the end of the loop since they will never be taken.
351 Then return, since no other action is needed here. */
353 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
354 don't do anything. */
356 if (GET_CODE (last_loop_insn
) == BARRIER
)
358 /* Delete the jump insn. This will delete the barrier also. */
359 delete_insn (PREV_INSN (last_loop_insn
));
361 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
364 rtx prev
= PREV_INSN (last_loop_insn
);
366 delete_insn (last_loop_insn
);
368 /* The immediately preceding insn may be a compare which must be
370 if (sets_cc0_p (prev
))
375 /* Remove the loop notes since this is no longer a loop. */
377 delete_insn (loop
->vtop
);
379 delete_insn (loop
->cont
);
381 delete_insn (loop_start
);
383 delete_insn (loop_end
);
387 else if (loop_info
->n_iterations
> 0
388 && loop_info
->n_iterations
* insn_count
< MAX_UNROLLED_INSNS
)
390 unroll_number
= loop_info
->n_iterations
;
391 unroll_type
= UNROLL_COMPLETELY
;
393 else if (loop_info
->n_iterations
> 0)
395 /* Try to factor the number of iterations. Don't bother with the
396 general case, only using 2, 3, 5, and 7 will get 75% of all
397 numbers theoretically, and almost all in practice. */
399 for (i
= 0; i
< NUM_FACTORS
; i
++)
400 factors
[i
].count
= 0;
402 temp
= loop_info
->n_iterations
;
403 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
404 while (temp
% factors
[i
].factor
== 0)
407 temp
= temp
/ factors
[i
].factor
;
410 /* Start with the larger factors first so that we generally
411 get lots of unrolling. */
415 for (i
= 3; i
>= 0; i
--)
416 while (factors
[i
].count
--)
418 if (temp
* factors
[i
].factor
< MAX_UNROLLED_INSNS
)
420 unroll_number
*= factors
[i
].factor
;
421 temp
*= factors
[i
].factor
;
427 /* If we couldn't find any factors, then unroll as in the normal
429 if (unroll_number
== 1)
431 if (loop_dump_stream
)
432 fprintf (loop_dump_stream
,
433 "Loop unrolling: No factors found.\n");
436 unroll_type
= UNROLL_MODULO
;
440 /* Default case, calculate number of times to unroll loop based on its
442 if (unroll_type
== UNROLL_NAIVE
)
444 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
446 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
452 /* Now we know how many times to unroll the loop. */
454 if (loop_dump_stream
)
455 fprintf (loop_dump_stream
,
456 "Unrolling loop %d times.\n", unroll_number
);
459 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
461 /* Loops of these types can start with jump down to the exit condition
462 in rare circumstances.
464 Consider a pair of nested loops where the inner loop is part
465 of the exit code for the outer loop.
467 In this case jump.c will not duplicate the exit test for the outer
468 loop, so it will start with a jump to the exit code.
470 Then consider if the inner loop turns out to iterate once and
471 only once. We will end up deleting the jumps associated with
472 the inner loop. However, the loop notes are not removed from
473 the instruction stream.
475 And finally assume that we can compute the number of iterations
478 In this case unroll may want to unroll the outer loop even though
479 it starts with a jump to the outer loop's exit code.
481 We could try to optimize this case, but it hardly seems worth it.
482 Just return without unrolling the loop in such cases. */
485 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
486 insn
= NEXT_INSN (insn
);
487 if (GET_CODE (insn
) == JUMP_INSN
)
491 if (unroll_type
== UNROLL_COMPLETELY
)
493 /* Completely unrolling the loop: Delete the compare and branch at
494 the end (the last two instructions). This delete must done at the
495 very end of loop unrolling, to avoid problems with calls to
496 back_branch_in_range_p, which is called by find_splittable_regs.
497 All increments of splittable bivs/givs are changed to load constant
500 copy_start
= loop_start
;
502 /* Set insert_before to the instruction immediately after the JUMP_INSN
503 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
504 the loop will be correctly handled by copy_loop_body. */
505 insert_before
= NEXT_INSN (last_loop_insn
);
507 /* Set copy_end to the insn before the jump at the end of the loop. */
508 if (GET_CODE (last_loop_insn
) == BARRIER
)
509 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
510 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
512 copy_end
= PREV_INSN (last_loop_insn
);
514 /* The instruction immediately before the JUMP_INSN may be a compare
515 instruction which we do not want to copy. */
516 if (sets_cc0_p (PREV_INSN (copy_end
)))
517 copy_end
= PREV_INSN (copy_end
);
522 /* We currently can't unroll a loop if it doesn't end with a
523 JUMP_INSN. There would need to be a mechanism that recognizes
524 this case, and then inserts a jump after each loop body, which
525 jumps to after the last loop body. */
526 if (loop_dump_stream
)
527 fprintf (loop_dump_stream
,
528 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
532 else if (unroll_type
== UNROLL_MODULO
)
534 /* Partially unrolling the loop: The compare and branch at the end
535 (the last two instructions) must remain. Don't copy the compare
536 and branch instructions at the end of the loop. Insert the unrolled
537 code immediately before the compare/branch at the end so that the
538 code will fall through to them as before. */
540 copy_start
= loop_start
;
542 /* Set insert_before to the jump insn at the end of the loop.
543 Set copy_end to before the jump insn at the end of the loop. */
544 if (GET_CODE (last_loop_insn
) == BARRIER
)
546 insert_before
= PREV_INSN (last_loop_insn
);
547 copy_end
= PREV_INSN (insert_before
);
549 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
551 insert_before
= last_loop_insn
;
553 /* The instruction immediately before the JUMP_INSN may be a compare
554 instruction which we do not want to copy or delete. */
555 if (sets_cc0_p (PREV_INSN (insert_before
)))
556 insert_before
= PREV_INSN (insert_before
);
558 copy_end
= PREV_INSN (insert_before
);
562 /* We currently can't unroll a loop if it doesn't end with a
563 JUMP_INSN. There would need to be a mechanism that recognizes
564 this case, and then inserts a jump after each loop body, which
565 jumps to after the last loop body. */
566 if (loop_dump_stream
)
567 fprintf (loop_dump_stream
,
568 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
574 /* Normal case: Must copy the compare and branch instructions at the
577 if (GET_CODE (last_loop_insn
) == BARRIER
)
579 /* Loop ends with an unconditional jump and a barrier.
580 Handle this like above, don't copy jump and barrier.
581 This is not strictly necessary, but doing so prevents generating
582 unconditional jumps to an immediately following label.
584 This will be corrected below if the target of this jump is
585 not the start_label. */
587 insert_before
= PREV_INSN (last_loop_insn
);
588 copy_end
= PREV_INSN (insert_before
);
590 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
592 /* Set insert_before to immediately after the JUMP_INSN, so that
593 NOTEs at the end of the loop will be correctly handled by
595 insert_before
= NEXT_INSN (last_loop_insn
);
596 copy_end
= last_loop_insn
;
600 /* We currently can't unroll a loop if it doesn't end with a
601 JUMP_INSN. There would need to be a mechanism that recognizes
602 this case, and then inserts a jump after each loop body, which
603 jumps to after the last loop body. */
604 if (loop_dump_stream
)
605 fprintf (loop_dump_stream
,
606 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
610 /* If copying exit test branches because they can not be eliminated,
611 then must convert the fall through case of the branch to a jump past
612 the end of the loop. Create a label to emit after the loop and save
613 it for later use. Do not use the label after the loop, if any, since
614 it might be used by insns outside the loop, or there might be insns
615 added before it later by final_[bg]iv_value which must be after
616 the real exit label. */
617 exit_label
= gen_label_rtx ();
620 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
621 insn
= NEXT_INSN (insn
);
623 if (GET_CODE (insn
) == JUMP_INSN
)
625 /* The loop starts with a jump down to the exit condition test.
626 Start copying the loop after the barrier following this
628 copy_start
= NEXT_INSN (insn
);
630 /* Splitting induction variables doesn't work when the loop is
631 entered via a jump to the bottom, because then we end up doing
632 a comparison against a new register for a split variable, but
633 we did not execute the set insn for the new register because
634 it was skipped over. */
635 splitting_not_safe
= 1;
636 if (loop_dump_stream
)
637 fprintf (loop_dump_stream
,
638 "Splitting not safe, because loop not entered at top.\n");
641 copy_start
= loop_start
;
644 /* This should always be the first label in the loop. */
645 start_label
= NEXT_INSN (copy_start
);
646 /* There may be a line number note and/or a loop continue note here. */
647 while (GET_CODE (start_label
) == NOTE
)
648 start_label
= NEXT_INSN (start_label
);
649 if (GET_CODE (start_label
) != CODE_LABEL
)
651 /* This can happen as a result of jump threading. If the first insns in
652 the loop test the same condition as the loop's backward jump, or the
653 opposite condition, then the backward jump will be modified to point
654 to elsewhere, and the loop's start label is deleted.
656 This case currently can not be handled by the loop unrolling code. */
658 if (loop_dump_stream
)
659 fprintf (loop_dump_stream
,
660 "Unrolling failure: unknown insns between BEG note and loop label.\n");
663 if (LABEL_NAME (start_label
))
665 /* The jump optimization pass must have combined the original start label
666 with a named label for a goto. We can't unroll this case because
667 jumps which go to the named label must be handled differently than
668 jumps to the loop start, and it is impossible to differentiate them
670 if (loop_dump_stream
)
671 fprintf (loop_dump_stream
,
672 "Unrolling failure: loop start label is gone\n");
676 if (unroll_type
== UNROLL_NAIVE
677 && GET_CODE (last_loop_insn
) == BARRIER
678 && GET_CODE (PREV_INSN (last_loop_insn
)) == JUMP_INSN
679 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
681 /* In this case, we must copy the jump and barrier, because they will
682 not be converted to jumps to an immediately following label. */
684 insert_before
= NEXT_INSN (last_loop_insn
);
685 copy_end
= last_loop_insn
;
688 if (unroll_type
== UNROLL_NAIVE
689 && GET_CODE (last_loop_insn
) == JUMP_INSN
690 && start_label
!= JUMP_LABEL (last_loop_insn
))
692 /* ??? The loop ends with a conditional branch that does not branch back
693 to the loop start label. In this case, we must emit an unconditional
694 branch to the loop exit after emitting the final branch.
695 copy_loop_body does not have support for this currently, so we
696 give up. It doesn't seem worthwhile to unroll anyways since
697 unrolling would increase the number of branch instructions
699 if (loop_dump_stream
)
700 fprintf (loop_dump_stream
,
701 "Unrolling failure: final conditional branch not to loop start\n");
705 /* Allocate a translation table for the labels and insn numbers.
706 They will be filled in as we copy the insns in the loop. */
708 max_labelno
= max_label_num ();
709 max_insnno
= get_max_uid ();
711 /* Various paths through the unroll code may reach the "egress" label
712 without initializing fields within the map structure.
714 To be safe, we use xcalloc to zero the memory. */
715 map
= (struct inline_remap
*) xcalloc (1, sizeof (struct inline_remap
));
717 /* Allocate the label map. */
721 map
->label_map
= (rtx
*) xmalloc (max_labelno
* sizeof (rtx
));
723 local_label
= (char *) xcalloc (max_labelno
, sizeof (char));
726 /* Search the loop and mark all local labels, i.e. the ones which have to
727 be distinct labels when copied. For all labels which might be
728 non-local, set their label_map entries to point to themselves.
729 If they happen to be local their label_map entries will be overwritten
730 before the loop body is copied. The label_map entries for local labels
731 will be set to a different value each time the loop body is copied. */
733 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
737 if (GET_CODE (insn
) == CODE_LABEL
)
738 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
739 else if (GET_CODE (insn
) == JUMP_INSN
)
741 if (JUMP_LABEL (insn
))
742 set_label_in_map (map
,
743 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)),
745 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
746 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
748 rtx pat
= PATTERN (insn
);
749 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
750 int len
= XVECLEN (pat
, diff_vec_p
);
753 for (i
= 0; i
< len
; i
++)
755 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
756 set_label_in_map (map
,
757 CODE_LABEL_NUMBER (label
),
762 else if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)))
763 set_label_in_map (map
, CODE_LABEL_NUMBER (XEXP (note
, 0)),
767 /* Allocate space for the insn map. */
769 map
->insn_map
= (rtx
*) xmalloc (max_insnno
* sizeof (rtx
));
771 /* Set this to zero, to indicate that we are doing loop unrolling,
772 not function inlining. */
773 map
->inline_target
= 0;
775 /* The register and constant maps depend on the number of registers
776 present, so the final maps can't be created until after
777 find_splittable_regs is called. However, they are needed for
778 preconditioning, so we create temporary maps when preconditioning
781 /* The preconditioning code may allocate two new pseudo registers. */
782 maxregnum
= max_reg_num ();
784 /* local_regno is only valid for regnos < max_local_regnum. */
785 max_local_regnum
= maxregnum
;
787 /* Allocate and zero out the splittable_regs and addr_combined_regs
788 arrays. These must be zeroed here because they will be used if
789 loop preconditioning is performed, and must be zero for that case.
791 It is safe to do this here, since the extra registers created by the
792 preconditioning code and find_splittable_regs will never be used
793 to access the splittable_regs[] and addr_combined_regs[] arrays. */
795 splittable_regs
= (rtx
*) xcalloc (maxregnum
, sizeof (rtx
));
796 derived_regs
= (char *) xcalloc (maxregnum
, sizeof (char));
797 splittable_regs_updates
= (int *) xcalloc (maxregnum
, sizeof (int));
799 = (struct induction
**) xcalloc (maxregnum
, sizeof (struct induction
*));
800 local_regno
= (char *) xcalloc (maxregnum
, sizeof (char));
802 /* Mark all local registers, i.e. the ones which are referenced only
804 if (INSN_UID (copy_end
) < max_uid_for_loop
)
806 int copy_start_luid
= INSN_LUID (copy_start
);
807 int copy_end_luid
= INSN_LUID (copy_end
);
809 /* If a register is used in the jump insn, we must not duplicate it
810 since it will also be used outside the loop. */
811 if (GET_CODE (copy_end
) == JUMP_INSN
)
814 /* If we have a target that uses cc0, then we also must not duplicate
815 the insn that sets cc0 before the jump insn, if one is present. */
817 if (GET_CODE (copy_end
) == JUMP_INSN
&& sets_cc0_p (PREV_INSN (copy_end
)))
821 /* If copy_start points to the NOTE that starts the loop, then we must
822 use the next luid, because invariant pseudo-regs moved out of the loop
823 have their lifetimes modified to start here, but they are not safe
825 if (copy_start
== loop_start
)
828 /* If a pseudo's lifetime is entirely contained within this loop, then we
829 can use a different pseudo in each unrolled copy of the loop. This
830 results in better code. */
831 /* We must limit the generic test to max_reg_before_loop, because only
832 these pseudo registers have valid regno_first_uid info. */
833 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_reg_before_loop
; ++r
)
834 if (REGNO_FIRST_UID (r
) > 0 && REGNO_FIRST_UID (r
) <= max_uid_for_loop
835 && uid_luid
[REGNO_FIRST_UID (r
)] >= copy_start_luid
836 && REGNO_LAST_UID (r
) > 0 && REGNO_LAST_UID (r
) <= max_uid_for_loop
837 && uid_luid
[REGNO_LAST_UID (r
)] <= copy_end_luid
)
839 /* However, we must also check for loop-carried dependencies.
840 If the value the pseudo has at the end of iteration X is
841 used by iteration X+1, then we can not use a different pseudo
842 for each unrolled copy of the loop. */
843 /* A pseudo is safe if regno_first_uid is a set, and this
844 set dominates all instructions from regno_first_uid to
846 /* ??? This check is simplistic. We would get better code if
847 this check was more sophisticated. */
848 if (set_dominates_use (r
, REGNO_FIRST_UID (r
), REGNO_LAST_UID (r
),
849 copy_start
, copy_end
))
852 if (loop_dump_stream
)
855 fprintf (loop_dump_stream
, "Marked reg %d as local\n", r
);
857 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
861 /* Givs that have been created from multiple biv increments always have
863 for (r
= first_increment_giv
; r
<= last_increment_giv
; r
++)
866 if (loop_dump_stream
)
867 fprintf (loop_dump_stream
, "Marked reg %d as local\n", r
);
871 /* If this loop requires exit tests when unrolled, check to see if we
872 can precondition the loop so as to make the exit tests unnecessary.
873 Just like variable splitting, this is not safe if the loop is entered
874 via a jump to the bottom. Also, can not do this if no strength
875 reduce info, because precondition_loop_p uses this info. */
877 /* Must copy the loop body for preconditioning before the following
878 find_splittable_regs call since that will emit insns which need to
879 be after the preconditioned loop copies, but immediately before the
880 unrolled loop copies. */
882 /* Also, it is not safe to split induction variables for the preconditioned
883 copies of the loop body. If we split induction variables, then the code
884 assumes that each induction variable can be represented as a function
885 of its initial value and the loop iteration number. This is not true
886 in this case, because the last preconditioned copy of the loop body
887 could be any iteration from the first up to the `unroll_number-1'th,
888 depending on the initial value of the iteration variable. Therefore
889 we can not split induction variables here, because we can not calculate
890 their value. Hence, this code must occur before find_splittable_regs
893 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
895 rtx initial_value
, final_value
, increment
;
896 enum machine_mode mode
;
898 if (precondition_loop_p (loop
,
899 &initial_value
, &final_value
, &increment
,
904 int abs_inc
, neg_inc
;
906 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
908 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
, maxregnum
,
910 global_const_equiv_varray
= map
->const_equiv_varray
;
912 init_reg_map (map
, maxregnum
);
914 /* Limit loop unrolling to 4, since this will make 7 copies of
916 if (unroll_number
> 4)
919 /* Save the absolute value of the increment, and also whether or
920 not it is negative. */
922 abs_inc
= INTVAL (increment
);
931 /* Calculate the difference between the final and initial values.
932 Final value may be a (plus (reg x) (const_int 1)) rtx.
933 Let the following cse pass simplify this if initial value is
936 We must copy the final and initial values here to avoid
937 improperly shared rtl. */
939 diff
= expand_binop (mode
, sub_optab
, copy_rtx (final_value
),
940 copy_rtx (initial_value
), NULL_RTX
, 0,
943 /* Now calculate (diff % (unroll * abs (increment))) by using an
945 diff
= expand_binop (GET_MODE (diff
), and_optab
, diff
,
946 GEN_INT (unroll_number
* abs_inc
- 1),
947 NULL_RTX
, 0, OPTAB_LIB_WIDEN
);
949 /* Now emit a sequence of branches to jump to the proper precond
952 labels
= (rtx
*) xmalloc (sizeof (rtx
) * unroll_number
);
953 for (i
= 0; i
< unroll_number
; i
++)
954 labels
[i
] = gen_label_rtx ();
956 /* Check for the case where the initial value is greater than or
957 equal to the final value. In that case, we want to execute
958 exactly one loop iteration. The code below will fail for this
959 case. This check does not apply if the loop has a NE
960 comparison at the end. */
962 if (loop_info
->comparison_code
!= NE
)
964 emit_cmp_and_jump_insns (initial_value
, final_value
,
966 NULL_RTX
, mode
, 0, 0, labels
[1]);
967 JUMP_LABEL (get_last_insn ()) = labels
[1];
968 LABEL_NUSES (labels
[1])++;
971 /* Assuming the unroll_number is 4, and the increment is 2, then
972 for a negative increment: for a positive increment:
973 diff = 0,1 precond 0 diff = 0,7 precond 0
974 diff = 2,3 precond 3 diff = 1,2 precond 1
975 diff = 4,5 precond 2 diff = 3,4 precond 2
976 diff = 6,7 precond 1 diff = 5,6 precond 3 */
978 /* We only need to emit (unroll_number - 1) branches here, the
979 last case just falls through to the following code. */
981 /* ??? This would give better code if we emitted a tree of branches
982 instead of the current linear list of branches. */
984 for (i
= 0; i
< unroll_number
- 1; i
++)
987 enum rtx_code cmp_code
;
989 /* For negative increments, must invert the constant compared
990 against, except when comparing against zero. */
998 cmp_const
= unroll_number
- i
;
1007 emit_cmp_and_jump_insns (diff
, GEN_INT (abs_inc
* cmp_const
),
1008 cmp_code
, NULL_RTX
, mode
, 0, 0,
1010 JUMP_LABEL (get_last_insn ()) = labels
[i
];
1011 LABEL_NUSES (labels
[i
])++;
1014 /* If the increment is greater than one, then we need another branch,
1015 to handle other cases equivalent to 0. */
1017 /* ??? This should be merged into the code above somehow to help
1018 simplify the code here, and reduce the number of branches emitted.
1019 For the negative increment case, the branch here could easily
1020 be merged with the `0' case branch above. For the positive
1021 increment case, it is not clear how this can be simplified. */
1026 enum rtx_code cmp_code
;
1030 cmp_const
= abs_inc
- 1;
1035 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
1039 emit_cmp_and_jump_insns (diff
, GEN_INT (cmp_const
), cmp_code
,
1040 NULL_RTX
, mode
, 0, 0, labels
[0]);
1041 JUMP_LABEL (get_last_insn ()) = labels
[0];
1042 LABEL_NUSES (labels
[0])++;
1045 sequence
= gen_sequence ();
1047 emit_insn_before (sequence
, loop_start
);
1049 /* Only the last copy of the loop body here needs the exit
1050 test, so set copy_end to exclude the compare/branch here,
1051 and then reset it inside the loop when get to the last
1054 if (GET_CODE (last_loop_insn
) == BARRIER
)
1055 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1056 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1058 copy_end
= PREV_INSN (last_loop_insn
);
1060 /* The immediately preceding insn may be a compare which we do not
1062 if (sets_cc0_p (PREV_INSN (copy_end
)))
1063 copy_end
= PREV_INSN (copy_end
);
1069 for (i
= 1; i
< unroll_number
; i
++)
1071 emit_label_after (labels
[unroll_number
- i
],
1072 PREV_INSN (loop_start
));
1074 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1075 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1076 (VARRAY_SIZE (map
->const_equiv_varray
)
1077 * sizeof (struct const_equiv_data
)));
1080 for (j
= 0; j
< max_labelno
; j
++)
1082 set_label_in_map (map
, j
, gen_label_rtx ());
1084 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1088 = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1089 record_base_value (REGNO (map
->reg_map
[r
]),
1090 regno_reg_rtx
[r
], 0);
1092 /* The last copy needs the compare/branch insns at the end,
1093 so reset copy_end here if the loop ends with a conditional
1096 if (i
== unroll_number
- 1)
1098 if (GET_CODE (last_loop_insn
) == BARRIER
)
1099 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1101 copy_end
= last_loop_insn
;
1104 /* None of the copies are the `last_iteration', so just
1105 pass zero for that parameter. */
1106 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, 0,
1107 unroll_type
, start_label
, loop_end
,
1108 loop_start
, copy_end
);
1110 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1112 if (GET_CODE (last_loop_insn
) == BARRIER
)
1114 insert_before
= PREV_INSN (last_loop_insn
);
1115 copy_end
= PREV_INSN (insert_before
);
1119 insert_before
= last_loop_insn
;
1121 /* The instruction immediately before the JUMP_INSN may be a compare
1122 instruction which we do not want to copy or delete. */
1123 if (sets_cc0_p (PREV_INSN (insert_before
)))
1124 insert_before
= PREV_INSN (insert_before
);
1126 copy_end
= PREV_INSN (insert_before
);
1129 /* Set unroll type to MODULO now. */
1130 unroll_type
= UNROLL_MODULO
;
1131 loop_preconditioned
= 1;
1138 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1139 the loop unless all loops are being unrolled. */
1140 if (unroll_type
== UNROLL_NAIVE
&& ! flag_unroll_all_loops
)
1142 if (loop_dump_stream
)
1143 fprintf (loop_dump_stream
, "Unrolling failure: Naive unrolling not being done.\n");
1147 /* At this point, we are guaranteed to unroll the loop. */
1149 /* Keep track of the unroll factor for the loop. */
1150 loop_info
->unroll_number
= unroll_number
;
1152 /* For each biv and giv, determine whether it can be safely split into
1153 a different variable for each unrolled copy of the loop body.
1154 We precalculate and save this info here, since computing it is
1157 Do this before deleting any instructions from the loop, so that
1158 back_branch_in_range_p will work correctly. */
1160 if (splitting_not_safe
)
1163 temp
= find_splittable_regs (loop
, unroll_type
,
1164 end_insert_before
, unroll_number
);
1166 /* find_splittable_regs may have created some new registers, so must
1167 reallocate the reg_map with the new larger size, and must realloc
1168 the constant maps also. */
1170 maxregnum
= max_reg_num ();
1171 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
1173 init_reg_map (map
, maxregnum
);
1175 if (map
->const_equiv_varray
== 0)
1176 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1177 maxregnum
+ temp
* unroll_number
* 2,
1179 global_const_equiv_varray
= map
->const_equiv_varray
;
1181 /* Search the list of bivs and givs to find ones which need to be remapped
1182 when split, and set their reg_map entry appropriately. */
1184 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
1186 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1187 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1189 /* Currently, non-reduced/final-value givs are never split. */
1190 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1191 if (REGNO (v
->src_reg
) != bl
->regno
)
1192 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1196 /* Use our current register alignment and pointer flags. */
1197 map
->regno_pointer_flag
= cfun
->emit
->regno_pointer_flag
;
1198 map
->regno_pointer_align
= cfun
->emit
->regno_pointer_align
;
1200 /* If the loop is being partially unrolled, and the iteration variables
1201 are being split, and are being renamed for the split, then must fix up
1202 the compare/jump instruction at the end of the loop to refer to the new
1203 registers. This compare isn't copied, so the registers used in it
1204 will never be replaced if it isn't done here. */
1206 if (unroll_type
== UNROLL_MODULO
)
1208 insn
= NEXT_INSN (copy_end
);
1209 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1210 PATTERN (insn
) = remap_split_bivs (PATTERN (insn
));
1213 /* For unroll_number times, make a copy of each instruction
1214 between copy_start and copy_end, and insert these new instructions
1215 before the end of the loop. */
1217 for (i
= 0; i
< unroll_number
; i
++)
1219 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1220 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1221 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1224 for (j
= 0; j
< max_labelno
; j
++)
1226 set_label_in_map (map
, j
, gen_label_rtx ());
1228 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1231 map
->reg_map
[r
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1232 record_base_value (REGNO (map
->reg_map
[r
]),
1233 regno_reg_rtx
[r
], 0);
1236 /* If loop starts with a branch to the test, then fix it so that
1237 it points to the test of the first unrolled copy of the loop. */
1238 if (i
== 0 && loop_start
!= copy_start
)
1240 insn
= PREV_INSN (copy_start
);
1241 pattern
= PATTERN (insn
);
1243 tem
= get_label_from_map (map
,
1245 (XEXP (SET_SRC (pattern
), 0)));
1246 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1248 /* Set the jump label so that it can be used by later loop unrolling
1250 JUMP_LABEL (insn
) = tem
;
1251 LABEL_NUSES (tem
)++;
1254 copy_loop_body (copy_start
, copy_end
, map
, exit_label
,
1255 i
== unroll_number
- 1, unroll_type
, start_label
,
1256 loop_end
, insert_before
, insert_before
);
1259 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1260 insn to be deleted. This prevents any runaway delete_insn call from
1261 more insns that it should, as it always stops at a CODE_LABEL. */
1263 /* Delete the compare and branch at the end of the loop if completely
1264 unrolling the loop. Deleting the backward branch at the end also
1265 deletes the code label at the start of the loop. This is done at
1266 the very end to avoid problems with back_branch_in_range_p. */
1268 if (unroll_type
== UNROLL_COMPLETELY
)
1269 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1271 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1273 /* Delete all of the original loop instructions. Don't delete the
1274 LOOP_BEG note, or the first code label in the loop. */
1276 insn
= NEXT_INSN (copy_start
);
1277 while (insn
!= safety_label
)
1279 /* ??? Don't delete named code labels. They will be deleted when the
1280 jump that references them is deleted. Otherwise, we end up deleting
1281 them twice, which causes them to completely disappear instead of turn
1282 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1283 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1284 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1285 associated LABEL_DECL to point to one of the new label instances. */
1286 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1287 if (insn
!= start_label
1288 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1289 && ! (GET_CODE (insn
) == NOTE
1290 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1291 insn
= delete_insn (insn
);
1293 insn
= NEXT_INSN (insn
);
1296 /* Can now delete the 'safety' label emitted to protect us from runaway
1297 delete_insn calls. */
1298 if (INSN_DELETED_P (safety_label
))
1300 delete_insn (safety_label
);
1302 /* If exit_label exists, emit it after the loop. Doing the emit here
1303 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1304 This is needed so that mostly_true_jump in reorg.c will treat jumps
1305 to this loop end label correctly, i.e. predict that they are usually
1308 emit_label_after (exit_label
, loop_end
);
1311 if (unroll_type
== UNROLL_COMPLETELY
)
1313 /* Remove the loop notes since this is no longer a loop. */
1315 delete_insn (loop
->vtop
);
1317 delete_insn (loop
->cont
);
1319 delete_insn (loop_start
);
1321 delete_insn (loop_end
);
1324 if (map
->const_equiv_varray
)
1325 VARRAY_FREE (map
->const_equiv_varray
);
1328 free (map
->label_map
);
1331 free (map
->insn_map
);
1332 free (splittable_regs
);
1333 free (derived_regs
);
1334 free (splittable_regs_updates
);
1335 free (addr_combined_regs
);
1338 free (map
->reg_map
);
1342 /* Return true if the loop can be safely, and profitably, preconditioned
1343 so that the unrolled copies of the loop body don't need exit tests.
1345 This only works if final_value, initial_value and increment can be
1346 determined, and if increment is a constant power of 2.
1347 If increment is not a power of 2, then the preconditioning modulo
1348 operation would require a real modulo instead of a boolean AND, and this
1349 is not considered `profitable'. */
1351 /* ??? If the loop is known to be executed very many times, or the machine
1352 has a very cheap divide instruction, then preconditioning is a win even
1353 when the increment is not a power of 2. Use RTX_COST to compute
1354 whether divide is cheap.
1355 ??? A divide by constant doesn't actually need a divide, look at
1356 expand_divmod. The reduced cost of this optimized modulo is not
1357 reflected in RTX_COST. */
1360 precondition_loop_p (loop
, initial_value
, final_value
, increment
, mode
)
1361 const struct loop
*loop
;
1362 rtx
*initial_value
, *final_value
, *increment
;
1363 enum machine_mode
*mode
;
1365 rtx loop_start
= loop
->start
;
1366 struct loop_info
*loop_info
= LOOP_INFO (loop
);
1368 if (loop_info
->n_iterations
> 0)
1370 *initial_value
= const0_rtx
;
1371 *increment
= const1_rtx
;
1372 *final_value
= GEN_INT (loop_info
->n_iterations
);
1375 if (loop_dump_stream
)
1377 fputs ("Preconditioning: Success, number of iterations known, ",
1379 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
1380 loop_info
->n_iterations
);
1381 fputs (".\n", loop_dump_stream
);
1386 if (loop_info
->initial_value
== 0)
1388 if (loop_dump_stream
)
1389 fprintf (loop_dump_stream
,
1390 "Preconditioning: Could not find initial value.\n");
1393 else if (loop_info
->increment
== 0)
1395 if (loop_dump_stream
)
1396 fprintf (loop_dump_stream
,
1397 "Preconditioning: Could not find increment value.\n");
1400 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1402 if (loop_dump_stream
)
1403 fprintf (loop_dump_stream
,
1404 "Preconditioning: Increment not a constant.\n");
1407 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1408 && (exact_log2 (- INTVAL (loop_info
->increment
)) < 0))
1410 if (loop_dump_stream
)
1411 fprintf (loop_dump_stream
,
1412 "Preconditioning: Increment not a constant power of 2.\n");
1416 /* Unsigned_compare and compare_dir can be ignored here, since they do
1417 not matter for preconditioning. */
1419 if (loop_info
->final_value
== 0)
1421 if (loop_dump_stream
)
1422 fprintf (loop_dump_stream
,
1423 "Preconditioning: EQ comparison loop.\n");
1427 /* Must ensure that final_value is invariant, so call
1428 loop_invariant_p to check. Before doing so, must check regno
1429 against max_reg_before_loop to make sure that the register is in
1430 the range covered by loop_invariant_p. If it isn't, then it is
1431 most likely a biv/giv which by definition are not invariant. */
1432 if ((GET_CODE (loop_info
->final_value
) == REG
1433 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1434 || (GET_CODE (loop_info
->final_value
) == PLUS
1435 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1436 || ! loop_invariant_p (loop
, loop_info
->final_value
))
1438 if (loop_dump_stream
)
1439 fprintf (loop_dump_stream
,
1440 "Preconditioning: Final value not invariant.\n");
1444 /* Fail for floating point values, since the caller of this function
1445 does not have code to deal with them. */
1446 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1447 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1449 if (loop_dump_stream
)
1450 fprintf (loop_dump_stream
,
1451 "Preconditioning: Floating point final or initial value.\n");
1455 /* Fail if loop_info->iteration_var is not live before loop_start,
1456 since we need to test its value in the preconditioning code. */
1458 if (uid_luid
[REGNO_FIRST_UID (REGNO (loop_info
->iteration_var
))]
1459 > INSN_LUID (loop_start
))
1461 if (loop_dump_stream
)
1462 fprintf (loop_dump_stream
,
1463 "Preconditioning: Iteration var not live before loop start.\n");
1467 /* Note that iteration_info biases the initial value for GIV iterators
1468 such as "while (i-- > 0)" so that we can calculate the number of
1469 iterations just like for BIV iterators.
1471 Also note that the absolute values of initial_value and
1472 final_value are unimportant as only their difference is used for
1473 calculating the number of loop iterations. */
1474 *initial_value
= loop_info
->initial_value
;
1475 *increment
= loop_info
->increment
;
1476 *final_value
= loop_info
->final_value
;
1478 /* Decide what mode to do these calculations in. Choose the larger
1479 of final_value's mode and initial_value's mode, or a full-word if
1480 both are constants. */
1481 *mode
= GET_MODE (*final_value
);
1482 if (*mode
== VOIDmode
)
1484 *mode
= GET_MODE (*initial_value
);
1485 if (*mode
== VOIDmode
)
1488 else if (*mode
!= GET_MODE (*initial_value
)
1489 && (GET_MODE_SIZE (*mode
)
1490 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1491 *mode
= GET_MODE (*initial_value
);
1494 if (loop_dump_stream
)
1495 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1500 /* All pseudo-registers must be mapped to themselves. Two hard registers
1501 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1502 REGNUM, to avoid function-inlining specific conversions of these
1503 registers. All other hard regs can not be mapped because they may be
1508 init_reg_map (map
, maxregnum
)
1509 struct inline_remap
*map
;
1514 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1515 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1516 /* Just clear the rest of the entries. */
1517 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1518 map
->reg_map
[i
] = 0;
1520 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1521 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1522 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1523 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1526 /* Strength-reduction will often emit code for optimized biv/givs which
1527 calculates their value in a temporary register, and then copies the result
1528 to the iv. This procedure reconstructs the pattern computing the iv;
1529 verifying that all operands are of the proper form.
1531 PATTERN must be the result of single_set.
1532 The return value is the amount that the giv is incremented by. */
1535 calculate_giv_inc (pattern
, src_insn
, regno
)
1536 rtx pattern
, src_insn
;
1540 rtx increment_total
= 0;
1544 /* Verify that we have an increment insn here. First check for a plus
1545 as the set source. */
1546 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1548 /* SR sometimes computes the new giv value in a temp, then copies it
1550 src_insn
= PREV_INSN (src_insn
);
1551 pattern
= PATTERN (src_insn
);
1552 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1555 /* The last insn emitted is not needed, so delete it to avoid confusing
1556 the second cse pass. This insn sets the giv unnecessarily. */
1557 delete_insn (get_last_insn ());
1560 /* Verify that we have a constant as the second operand of the plus. */
1561 increment
= XEXP (SET_SRC (pattern
), 1);
1562 if (GET_CODE (increment
) != CONST_INT
)
1564 /* SR sometimes puts the constant in a register, especially if it is
1565 too big to be an add immed operand. */
1566 src_insn
= PREV_INSN (src_insn
);
1567 increment
= SET_SRC (PATTERN (src_insn
));
1569 /* SR may have used LO_SUM to compute the constant if it is too large
1570 for a load immed operand. In this case, the constant is in operand
1571 one of the LO_SUM rtx. */
1572 if (GET_CODE (increment
) == LO_SUM
)
1573 increment
= XEXP (increment
, 1);
1575 /* Some ports store large constants in memory and add a REG_EQUAL
1576 note to the store insn. */
1577 else if (GET_CODE (increment
) == MEM
)
1579 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1581 increment
= XEXP (note
, 0);
1584 else if (GET_CODE (increment
) == IOR
1585 || GET_CODE (increment
) == ASHIFT
1586 || GET_CODE (increment
) == PLUS
)
1588 /* The rs6000 port loads some constants with IOR.
1589 The alpha port loads some constants with ASHIFT and PLUS. */
1590 rtx second_part
= XEXP (increment
, 1);
1591 enum rtx_code code
= GET_CODE (increment
);
1593 src_insn
= PREV_INSN (src_insn
);
1594 increment
= SET_SRC (PATTERN (src_insn
));
1595 /* Don't need the last insn anymore. */
1596 delete_insn (get_last_insn ());
1598 if (GET_CODE (second_part
) != CONST_INT
1599 || GET_CODE (increment
) != CONST_INT
)
1603 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1604 else if (code
== PLUS
)
1605 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1607 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1610 if (GET_CODE (increment
) != CONST_INT
)
1613 /* The insn loading the constant into a register is no longer needed,
1615 delete_insn (get_last_insn ());
1618 if (increment_total
)
1619 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1621 increment_total
= increment
;
1623 /* Check that the source register is the same as the register we expected
1624 to see as the source. If not, something is seriously wrong. */
1625 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1626 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1628 /* Some machines (e.g. the romp), may emit two add instructions for
1629 certain constants, so lets try looking for another add immediately
1630 before this one if we have only seen one add insn so far. */
1636 src_insn
= PREV_INSN (src_insn
);
1637 pattern
= PATTERN (src_insn
);
1639 delete_insn (get_last_insn ());
1647 return increment_total
;
1650 /* Copy REG_NOTES, except for insn references, because not all insn_map
1651 entries are valid yet. We do need to copy registers now though, because
1652 the reg_map entries can change during copying. */
1655 initial_reg_note_copy (notes
, map
)
1657 struct inline_remap
*map
;
1664 copy
= rtx_alloc (GET_CODE (notes
));
1665 PUT_MODE (copy
, GET_MODE (notes
));
1667 if (GET_CODE (notes
) == EXPR_LIST
)
1668 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
, 0);
1669 else if (GET_CODE (notes
) == INSN_LIST
)
1670 /* Don't substitute for these yet. */
1671 XEXP (copy
, 0) = XEXP (notes
, 0);
1675 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1680 /* Fixup insn references in copied REG_NOTES. */
1683 final_reg_note_copy (notes
, map
)
1685 struct inline_remap
*map
;
1689 for (note
= notes
; note
; note
= XEXP (note
, 1))
1690 if (GET_CODE (note
) == INSN_LIST
)
1691 XEXP (note
, 0) = map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1694 /* Copy each instruction in the loop, substituting from map as appropriate.
1695 This is very similar to a loop in expand_inline_function. */
1698 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1699 unroll_type
, start_label
, loop_end
, insert_before
,
1701 rtx copy_start
, copy_end
;
1702 struct inline_remap
*map
;
1705 enum unroll_types unroll_type
;
1706 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1709 rtx set
, tem
, copy
= NULL_RTX
;
1710 int dest_reg_was_split
, i
;
1714 rtx final_label
= 0;
1715 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1717 /* If this isn't the last iteration, then map any references to the
1718 start_label to final_label. Final label will then be emitted immediately
1719 after the end of this loop body if it was ever used.
1721 If this is the last iteration, then map references to the start_label
1723 if (! last_iteration
)
1725 final_label
= gen_label_rtx ();
1726 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
),
1730 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1734 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1735 Else gen_sequence could return a raw pattern for a jump which we pass
1736 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1737 a variety of losing behaviors later. */
1738 emit_note (0, NOTE_INSN_DELETED
);
1743 insn
= NEXT_INSN (insn
);
1745 map
->orig_asm_operands_vector
= 0;
1747 switch (GET_CODE (insn
))
1750 pattern
= PATTERN (insn
);
1754 /* Check to see if this is a giv that has been combined with
1755 some split address givs. (Combined in the sense that
1756 `combine_givs' in loop.c has put two givs in the same register.)
1757 In this case, we must search all givs based on the same biv to
1758 find the address givs. Then split the address givs.
1759 Do this before splitting the giv, since that may map the
1760 SET_DEST to a new register. */
1762 if ((set
= single_set (insn
))
1763 && GET_CODE (SET_DEST (set
)) == REG
1764 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1766 struct iv_class
*bl
;
1767 struct induction
*v
, *tv
;
1768 unsigned int regno
= REGNO (SET_DEST (set
));
1770 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1771 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
1773 /* Although the giv_inc amount is not needed here, we must call
1774 calculate_giv_inc here since it might try to delete the
1775 last insn emitted. If we wait until later to call it,
1776 we might accidentally delete insns generated immediately
1777 below by emit_unrolled_add. */
1779 if (! derived_regs
[regno
])
1780 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1782 /* Now find all address giv's that were combined with this
1784 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1785 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1789 /* If this DEST_ADDR giv was not split, then ignore it. */
1790 if (*tv
->location
!= tv
->dest_reg
)
1793 /* Scale this_giv_inc if the multiplicative factors of
1794 the two givs are different. */
1795 this_giv_inc
= INTVAL (giv_inc
);
1796 if (tv
->mult_val
!= v
->mult_val
)
1797 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1798 * INTVAL (tv
->mult_val
));
1800 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1801 *tv
->location
= tv
->dest_reg
;
1803 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1805 /* Must emit an insn to increment the split address
1806 giv. Add in the const_adjust field in case there
1807 was a constant eliminated from the address. */
1808 rtx value
, dest_reg
;
1810 /* tv->dest_reg will be either a bare register,
1811 or else a register plus a constant. */
1812 if (GET_CODE (tv
->dest_reg
) == REG
)
1813 dest_reg
= tv
->dest_reg
;
1815 dest_reg
= XEXP (tv
->dest_reg
, 0);
1817 /* Check for shared address givs, and avoid
1818 incrementing the shared pseudo reg more than
1820 if (! tv
->same_insn
&& ! tv
->shared
)
1822 /* tv->dest_reg may actually be a (PLUS (REG)
1823 (CONST)) here, so we must call plus_constant
1824 to add the const_adjust amount before calling
1825 emit_unrolled_add below. */
1826 value
= plus_constant (tv
->dest_reg
,
1829 if (GET_CODE (value
) == PLUS
)
1831 /* The constant could be too large for an add
1832 immediate, so can't directly emit an insn
1834 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1839 /* Reset the giv to be just the register again, in case
1840 it is used after the set we have just emitted.
1841 We must subtract the const_adjust factor added in
1843 tv
->dest_reg
= plus_constant (dest_reg
,
1844 - tv
->const_adjust
);
1845 *tv
->location
= tv
->dest_reg
;
1850 /* If this is a setting of a splittable variable, then determine
1851 how to split the variable, create a new set based on this split,
1852 and set up the reg_map so that later uses of the variable will
1853 use the new split variable. */
1855 dest_reg_was_split
= 0;
1857 if ((set
= single_set (insn
))
1858 && GET_CODE (SET_DEST (set
)) == REG
1859 && splittable_regs
[REGNO (SET_DEST (set
))])
1861 unsigned int regno
= REGNO (SET_DEST (set
));
1862 unsigned int src_regno
;
1864 dest_reg_was_split
= 1;
1866 giv_dest_reg
= SET_DEST (set
);
1867 if (derived_regs
[regno
])
1869 /* ??? This relies on SET_SRC (SET) to be of
1870 the form (plus (reg) (const_int)), and thus
1871 forces recombine_givs to restrict the kind
1872 of giv derivations it does before unrolling. */
1873 giv_src_reg
= XEXP (SET_SRC (set
), 0);
1874 giv_inc
= XEXP (SET_SRC (set
), 1);
1878 giv_src_reg
= giv_dest_reg
;
1879 /* Compute the increment value for the giv, if it wasn't
1880 already computed above. */
1882 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1884 src_regno
= REGNO (giv_src_reg
);
1886 if (unroll_type
== UNROLL_COMPLETELY
)
1888 /* Completely unrolling the loop. Set the induction
1889 variable to a known constant value. */
1891 /* The value in splittable_regs may be an invariant
1892 value, so we must use plus_constant here. */
1893 splittable_regs
[regno
]
1894 = plus_constant (splittable_regs
[src_regno
],
1897 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1899 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1900 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1904 /* The splittable_regs value must be a REG or a
1905 CONST_INT, so put the entire value in the giv_src_reg
1907 giv_src_reg
= splittable_regs
[regno
];
1908 giv_inc
= const0_rtx
;
1913 /* Partially unrolling loop. Create a new pseudo
1914 register for the iteration variable, and set it to
1915 be a constant plus the original register. Except
1916 on the last iteration, when the result has to
1917 go back into the original iteration var register. */
1919 /* Handle bivs which must be mapped to a new register
1920 when split. This happens for bivs which need their
1921 final value set before loop entry. The new register
1922 for the biv was stored in the biv's first struct
1923 induction entry by find_splittable_regs. */
1925 if (regno
< max_reg_before_loop
1926 && REG_IV_TYPE (regno
) == BASIC_INDUCT
)
1928 giv_src_reg
= reg_biv_class
[regno
]->biv
->src_reg
;
1929 giv_dest_reg
= giv_src_reg
;
1933 /* If non-reduced/final-value givs were split, then
1934 this would have to remap those givs also. See
1935 find_splittable_regs. */
1938 splittable_regs
[regno
]
1939 = GEN_INT (INTVAL (giv_inc
)
1940 + INTVAL (splittable_regs
[src_regno
]));
1941 giv_inc
= splittable_regs
[regno
];
1943 /* Now split the induction variable by changing the dest
1944 of this insn to a new register, and setting its
1945 reg_map entry to point to this new register.
1947 If this is the last iteration, and this is the last insn
1948 that will update the iv, then reuse the original dest,
1949 to ensure that the iv will have the proper value when
1950 the loop exits or repeats.
1952 Using splittable_regs_updates here like this is safe,
1953 because it can only be greater than one if all
1954 instructions modifying the iv are always executed in
1957 if (! last_iteration
1958 || (splittable_regs_updates
[regno
]-- != 1))
1960 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
1962 map
->reg_map
[regno
] = tem
;
1963 record_base_value (REGNO (tem
),
1964 giv_inc
== const0_rtx
1966 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
1967 giv_src_reg
, giv_inc
),
1971 map
->reg_map
[regno
] = giv_src_reg
;
1974 /* The constant being added could be too large for an add
1975 immediate, so can't directly emit an insn here. */
1976 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
1977 copy
= get_last_insn ();
1978 pattern
= PATTERN (copy
);
1982 pattern
= copy_rtx_and_substitute (pattern
, map
, 0);
1983 copy
= emit_insn (pattern
);
1985 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1988 /* If this insn is setting CC0, it may need to look at
1989 the insn that uses CC0 to see what type of insn it is.
1990 In that case, the call to recog via validate_change will
1991 fail. So don't substitute constants here. Instead,
1992 do it when we emit the following insn.
1994 For example, see the pyr.md file. That machine has signed and
1995 unsigned compares. The compare patterns must check the
1996 following branch insn to see which what kind of compare to
1999 If the previous insn set CC0, substitute constants on it as
2001 if (sets_cc0_p (PATTERN (copy
)) != 0)
2006 try_constants (cc0_insn
, map
);
2008 try_constants (copy
, map
);
2011 try_constants (copy
, map
);
2014 /* Make split induction variable constants `permanent' since we
2015 know there are no backward branches across iteration variable
2016 settings which would invalidate this. */
2017 if (dest_reg_was_split
)
2019 int regno
= REGNO (SET_DEST (set
));
2021 if ((size_t) regno
< VARRAY_SIZE (map
->const_equiv_varray
)
2022 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
2024 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
2029 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2030 copy
= emit_jump_insn (pattern
);
2031 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2033 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
2034 && ! last_iteration
)
2036 /* This is a branch to the beginning of the loop; this is the
2037 last insn being copied; and this is not the last iteration.
2038 In this case, we want to change the original fall through
2039 case to be a branch past the end of the loop, and the
2040 original jump label case to fall_through. */
2042 if (invert_exp (pattern
, copy
))
2044 if (! redirect_exp (&pattern
,
2045 get_label_from_map (map
,
2047 (JUMP_LABEL (insn
))),
2054 rtx lab
= gen_label_rtx ();
2055 /* Can't do it by reversing the jump (probably because we
2056 couldn't reverse the conditions), so emit a new
2057 jump_insn after COPY, and redirect the jump around
2059 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2060 jmp
= emit_barrier_after (jmp
);
2061 emit_label_after (lab
, jmp
);
2062 LABEL_NUSES (lab
) = 0;
2063 if (! redirect_exp (&pattern
,
2064 get_label_from_map (map
,
2066 (JUMP_LABEL (insn
))),
2074 try_constants (cc0_insn
, map
);
2077 try_constants (copy
, map
);
2079 /* Set the jump label of COPY correctly to avoid problems with
2080 later passes of unroll_loop, if INSN had jump label set. */
2081 if (JUMP_LABEL (insn
))
2085 /* Can't use the label_map for every insn, since this may be
2086 the backward branch, and hence the label was not mapped. */
2087 if ((set
= single_set (copy
)))
2089 tem
= SET_SRC (set
);
2090 if (GET_CODE (tem
) == LABEL_REF
)
2091 label
= XEXP (tem
, 0);
2092 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2094 if (XEXP (tem
, 1) != pc_rtx
)
2095 label
= XEXP (XEXP (tem
, 1), 0);
2097 label
= XEXP (XEXP (tem
, 2), 0);
2101 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2102 JUMP_LABEL (copy
) = label
;
2105 /* An unrecognizable jump insn, probably the entry jump
2106 for a switch statement. This label must have been mapped,
2107 so just use the label_map to get the new jump label. */
2109 = get_label_from_map (map
,
2110 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2113 /* If this is a non-local jump, then must increase the label
2114 use count so that the label will not be deleted when the
2115 original jump is deleted. */
2116 LABEL_NUSES (JUMP_LABEL (copy
))++;
2118 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2119 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2121 rtx pat
= PATTERN (copy
);
2122 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2123 int len
= XVECLEN (pat
, diff_vec_p
);
2126 for (i
= 0; i
< len
; i
++)
2127 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2130 /* If this used to be a conditional jump insn but whose branch
2131 direction is now known, we must do something special. */
2132 if (condjump_p (insn
) && !simplejump_p (insn
) && map
->last_pc_value
)
2135 /* If the previous insn set cc0 for us, delete it. */
2136 if (sets_cc0_p (PREV_INSN (copy
)))
2137 delete_insn (PREV_INSN (copy
));
2140 /* If this is now a no-op, delete it. */
2141 if (map
->last_pc_value
== pc_rtx
)
2143 /* Don't let delete_insn delete the label referenced here,
2144 because we might possibly need it later for some other
2145 instruction in the loop. */
2146 if (JUMP_LABEL (copy
))
2147 LABEL_NUSES (JUMP_LABEL (copy
))++;
2149 if (JUMP_LABEL (copy
))
2150 LABEL_NUSES (JUMP_LABEL (copy
))--;
2154 /* Otherwise, this is unconditional jump so we must put a
2155 BARRIER after it. We could do some dead code elimination
2156 here, but jump.c will do it just as well. */
2162 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2163 copy
= emit_call_insn (pattern
);
2164 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2166 /* Because the USAGE information potentially contains objects other
2167 than hard registers, we need to copy it. */
2168 CALL_INSN_FUNCTION_USAGE (copy
)
2169 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
),
2174 try_constants (cc0_insn
, map
);
2177 try_constants (copy
, map
);
2179 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2180 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2181 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2185 /* If this is the loop start label, then we don't need to emit a
2186 copy of this label since no one will use it. */
2188 if (insn
!= start_label
)
2190 copy
= emit_label (get_label_from_map (map
,
2191 CODE_LABEL_NUMBER (insn
)));
2197 copy
= emit_barrier ();
2201 /* VTOP and CONT notes are valid only before the loop exit test.
2202 If placed anywhere else, loop may generate bad code. */
2203 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2204 the associated rtl. We do not want to share the structure in
2207 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2208 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2209 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2210 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2211 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2212 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2213 NOTE_LINE_NUMBER (insn
));
2222 map
->insn_map
[INSN_UID (insn
)] = copy
;
2224 while (insn
!= copy_end
);
2226 /* Now finish coping the REG_NOTES. */
2230 insn
= NEXT_INSN (insn
);
2231 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2232 || GET_CODE (insn
) == CALL_INSN
)
2233 && map
->insn_map
[INSN_UID (insn
)])
2234 final_reg_note_copy (REG_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2236 while (insn
!= copy_end
);
2238 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2239 each of these notes here, since there may be some important ones, such as
2240 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2241 iteration, because the original notes won't be deleted.
2243 We can't use insert_before here, because when from preconditioning,
2244 insert_before points before the loop. We can't use copy_end, because
2245 there may be insns already inserted after it (which we don't want to
2246 copy) when not from preconditioning code. */
2248 if (! last_iteration
)
2250 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2252 /* VTOP notes are valid only before the loop exit test.
2253 If placed anywhere else, loop may generate bad code.
2254 There is no need to test for NOTE_INSN_LOOP_CONT notes
2255 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2256 instructions before the last insn in the loop, and if the
2257 end test is that short, there will be a VTOP note between
2258 the CONT note and the test. */
2259 if (GET_CODE (insn
) == NOTE
2260 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2261 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2262 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
)
2263 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2267 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2268 emit_label (final_label
);
2270 tem
= gen_sequence ();
2272 emit_insn_before (tem
, insert_before
);
2275 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2276 emitted. This will correctly handle the case where the increment value
2277 won't fit in the immediate field of a PLUS insns. */
2280 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2281 rtx dest_reg
, src_reg
, increment
;
2285 result
= expand_binop (GET_MODE (dest_reg
), add_optab
, src_reg
, increment
,
2286 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2288 if (dest_reg
!= result
)
2289 emit_move_insn (dest_reg
, result
);
2292 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2293 is a backward branch in that range that branches to somewhere between
2294 LOOP->START and INSN. Returns 0 otherwise. */
2296 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2297 In practice, this is not a problem, because this function is seldom called,
2298 and uses a negligible amount of CPU time on average. */
2301 back_branch_in_range_p (loop
, insn
)
2302 const struct loop
*loop
;
2305 rtx p
, q
, target_insn
;
2306 rtx loop_start
= loop
->start
;
2307 rtx loop_end
= loop
->end
;
2308 rtx orig_loop_end
= loop
->end
;
2310 /* Stop before we get to the backward branch at the end of the loop. */
2311 loop_end
= prev_nonnote_insn (loop_end
);
2312 if (GET_CODE (loop_end
) == BARRIER
)
2313 loop_end
= PREV_INSN (loop_end
);
2315 /* Check in case insn has been deleted, search forward for first non
2316 deleted insn following it. */
2317 while (INSN_DELETED_P (insn
))
2318 insn
= NEXT_INSN (insn
);
2320 /* Check for the case where insn is the last insn in the loop. Deal
2321 with the case where INSN was a deleted loop test insn, in which case
2322 it will now be the NOTE_LOOP_END. */
2323 if (insn
== loop_end
|| insn
== orig_loop_end
)
2326 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2328 if (GET_CODE (p
) == JUMP_INSN
)
2330 target_insn
= JUMP_LABEL (p
);
2332 /* Search from loop_start to insn, to see if one of them is
2333 the target_insn. We can't use INSN_LUID comparisons here,
2334 since insn may not have an LUID entry. */
2335 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2336 if (q
== target_insn
)
2344 /* Try to generate the simplest rtx for the expression
2345 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2349 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2350 rtx mult1
, mult2
, add1
;
2351 enum machine_mode mode
;
2356 /* The modes must all be the same. This should always be true. For now,
2357 check to make sure. */
2358 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2359 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2360 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2363 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2364 will be a constant. */
2365 if (GET_CODE (mult1
) == CONST_INT
)
2372 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2374 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2376 /* Again, put the constant second. */
2377 if (GET_CODE (add1
) == CONST_INT
)
2384 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2386 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2391 /* Searches the list of induction struct's for the biv BL, to try to calculate
2392 the total increment value for one iteration of the loop as a constant.
2394 Returns the increment value as an rtx, simplified as much as possible,
2395 if it can be calculated. Otherwise, returns 0. */
2398 biv_total_increment (bl
)
2399 struct iv_class
*bl
;
2401 struct induction
*v
;
2404 /* For increment, must check every instruction that sets it. Each
2405 instruction must be executed only once each time through the loop.
2406 To verify this, we check that the insn is always executed, and that
2407 there are no backward branches after the insn that branch to before it.
2408 Also, the insn must have a mult_val of one (to make sure it really is
2411 result
= const0_rtx
;
2412 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2414 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2415 && ! v
->maybe_multiple
)
2416 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2424 /* Determine the initial value of the iteration variable, and the amount
2425 that it is incremented each loop. Use the tables constructed by
2426 the strength reduction pass to calculate these values.
2428 Initial_value and/or increment are set to zero if their values could not
2432 iteration_info (loop
, iteration_var
, initial_value
, increment
)
2433 const struct loop
*loop ATTRIBUTE_UNUSED
;
2434 rtx iteration_var
, *initial_value
, *increment
;
2436 struct iv_class
*bl
;
2438 /* Clear the result values, in case no answer can be found. */
2442 /* The iteration variable can be either a giv or a biv. Check to see
2443 which it is, and compute the variable's initial value, and increment
2444 value if possible. */
2446 /* If this is a new register, can't handle it since we don't have any
2447 reg_iv_type entry for it. */
2448 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
)
2450 if (loop_dump_stream
)
2451 fprintf (loop_dump_stream
,
2452 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2456 /* Reject iteration variables larger than the host wide int size, since they
2457 could result in a number of iterations greater than the range of our
2458 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2459 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
2460 > HOST_BITS_PER_WIDE_INT
))
2462 if (loop_dump_stream
)
2463 fprintf (loop_dump_stream
,
2464 "Loop unrolling: Iteration var rejected because mode too large.\n");
2467 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
2469 if (loop_dump_stream
)
2470 fprintf (loop_dump_stream
,
2471 "Loop unrolling: Iteration var not an integer.\n");
2474 else if (REG_IV_TYPE (REGNO (iteration_var
)) == BASIC_INDUCT
)
2476 /* When reg_iv_type / reg_iv_info is resized for biv increments
2477 that are turned into givs, reg_biv_class is not resized.
2478 So check here that we don't make an out-of-bounds access. */
2479 if (REGNO (iteration_var
) >= max_reg_before_loop
)
2482 /* Grab initial value, only useful if it is a constant. */
2483 bl
= reg_biv_class
[REGNO (iteration_var
)];
2484 *initial_value
= bl
->initial_value
;
2486 *increment
= biv_total_increment (bl
);
2488 else if (REG_IV_TYPE (REGNO (iteration_var
)) == GENERAL_INDUCT
)
2490 HOST_WIDE_INT offset
= 0;
2491 struct induction
*v
= REG_IV_INFO (REGNO (iteration_var
));
2493 if (REGNO (v
->src_reg
) >= max_reg_before_loop
)
2496 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
2498 /* Increment value is mult_val times the increment value of the biv. */
2500 *increment
= biv_total_increment (bl
);
2503 struct induction
*biv_inc
;
2506 = fold_rtx_mult_add (v
->mult_val
, *increment
, const0_rtx
, v
->mode
);
2507 /* The caller assumes that one full increment has occured at the
2508 first loop test. But that's not true when the biv is incremented
2509 after the giv is set (which is the usual case), e.g.:
2510 i = 6; do {;} while (i++ < 9) .
2511 Therefore, we bias the initial value by subtracting the amount of
2512 the increment that occurs between the giv set and the giv test. */
2513 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
2515 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
2516 offset
-= INTVAL (biv_inc
->add_val
);
2518 offset
*= INTVAL (v
->mult_val
);
2520 if (loop_dump_stream
)
2521 fprintf (loop_dump_stream
,
2522 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2524 /* Initial value is mult_val times the biv's initial value plus
2525 add_val. Only useful if it is a constant. */
2527 = fold_rtx_mult_add (v
->mult_val
,
2528 plus_constant (bl
->initial_value
, offset
),
2529 v
->add_val
, v
->mode
);
2533 if (loop_dump_stream
)
2534 fprintf (loop_dump_stream
,
2535 "Loop unrolling: Not basic or general induction var.\n");
2541 /* For each biv and giv, determine whether it can be safely split into
2542 a different variable for each unrolled copy of the loop body. If it
2543 is safe to split, then indicate that by saving some useful info
2544 in the splittable_regs array.
2546 If the loop is being completely unrolled, then splittable_regs will hold
2547 the current value of the induction variable while the loop is unrolled.
2548 It must be set to the initial value of the induction variable here.
2549 Otherwise, splittable_regs will hold the difference between the current
2550 value of the induction variable and the value the induction variable had
2551 at the top of the loop. It must be set to the value 0 here.
2553 Returns the total number of instructions that set registers that are
2556 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2557 constant values are unnecessary, since we can easily calculate increment
2558 values in this case even if nothing is constant. The increment value
2559 should not involve a multiply however. */
2561 /* ?? Even if the biv/giv increment values aren't constant, it may still
2562 be beneficial to split the variable if the loop is only unrolled a few
2563 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2566 find_splittable_regs (loop
, unroll_type
, end_insert_before
, unroll_number
)
2567 const struct loop
*loop
;
2568 enum unroll_types unroll_type
;
2569 rtx end_insert_before
;
2572 struct iv_class
*bl
;
2573 struct induction
*v
;
2575 rtx biv_final_value
;
2578 rtx loop_start
= loop
->start
;
2579 rtx loop_end
= loop
->end
;
2581 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
2583 /* Biv_total_increment must return a constant value,
2584 otherwise we can not calculate the split values. */
2586 increment
= biv_total_increment (bl
);
2587 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2590 /* The loop must be unrolled completely, or else have a known number
2591 of iterations and only one exit, or else the biv must be dead
2592 outside the loop, or else the final value must be known. Otherwise,
2593 it is unsafe to split the biv since it may not have the proper
2594 value on loop exit. */
2596 /* loop_number_exit_count is non-zero if the loop has an exit other than
2597 a fall through at the end. */
2600 biv_final_value
= 0;
2601 if (unroll_type
!= UNROLL_COMPLETELY
2602 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2603 && (uid_luid
[REGNO_LAST_UID (bl
->regno
)] >= INSN_LUID (loop_end
)
2605 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2606 || (uid_luid
[REGNO_FIRST_UID (bl
->regno
)]
2607 < INSN_LUID (bl
->init_insn
))
2608 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2609 && ! (biv_final_value
= final_biv_value (loop
, bl
)))
2612 /* If any of the insns setting the BIV don't do so with a simple
2613 PLUS, we don't know how to split it. */
2614 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2615 if ((tem
= single_set (v
->insn
)) == 0
2616 || GET_CODE (SET_DEST (tem
)) != REG
2617 || REGNO (SET_DEST (tem
)) != bl
->regno
2618 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2621 /* If final value is non-zero, then must emit an instruction which sets
2622 the value of the biv to the proper value. This is done after
2623 handling all of the givs, since some of them may need to use the
2624 biv's value in their initialization code. */
2626 /* This biv is splittable. If completely unrolling the loop, save
2627 the biv's initial value. Otherwise, save the constant zero. */
2629 if (biv_splittable
== 1)
2631 if (unroll_type
== UNROLL_COMPLETELY
)
2633 /* If the initial value of the biv is itself (i.e. it is too
2634 complicated for strength_reduce to compute), or is a hard
2635 register, or it isn't invariant, then we must create a new
2636 pseudo reg to hold the initial value of the biv. */
2638 if (GET_CODE (bl
->initial_value
) == REG
2639 && (REGNO (bl
->initial_value
) == bl
->regno
2640 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2641 || ! loop_invariant_p (loop
, bl
->initial_value
)))
2643 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2645 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2646 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2649 if (loop_dump_stream
)
2650 fprintf (loop_dump_stream
, "Biv %d initial value remapped to %d.\n",
2651 bl
->regno
, REGNO (tem
));
2653 splittable_regs
[bl
->regno
] = tem
;
2656 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2659 splittable_regs
[bl
->regno
] = const0_rtx
;
2661 /* Save the number of instructions that modify the biv, so that
2662 we can treat the last one specially. */
2664 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2665 result
+= bl
->biv_count
;
2667 if (loop_dump_stream
)
2668 fprintf (loop_dump_stream
,
2669 "Biv %d safe to split.\n", bl
->regno
);
2672 /* Check every giv that depends on this biv to see whether it is
2673 splittable also. Even if the biv isn't splittable, givs which
2674 depend on it may be splittable if the biv is live outside the
2675 loop, and the givs aren't. */
2677 result
+= find_splittable_givs (loop
, bl
, unroll_type
, increment
,
2680 /* If final value is non-zero, then must emit an instruction which sets
2681 the value of the biv to the proper value. This is done after
2682 handling all of the givs, since some of them may need to use the
2683 biv's value in their initialization code. */
2684 if (biv_final_value
)
2686 /* If the loop has multiple exits, emit the insns before the
2687 loop to ensure that it will always be executed no matter
2688 how the loop exits. Otherwise emit the insn after the loop,
2689 since this is slightly more efficient. */
2690 if (! loop
->exit_count
)
2691 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2696 /* Create a new register to hold the value of the biv, and then
2697 set the biv to its final value before the loop start. The biv
2698 is set to its final value before loop start to ensure that
2699 this insn will always be executed, no matter how the loop
2701 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2702 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2704 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2706 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2710 if (loop_dump_stream
)
2711 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2712 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2714 /* Set up the mapping from the original biv register to the new
2716 bl
->biv
->src_reg
= tem
;
2723 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2724 for the instruction that is using it. Do not make any changes to that
2728 verify_addresses (v
, giv_inc
, unroll_number
)
2729 struct induction
*v
;
2734 rtx orig_addr
= *v
->location
;
2735 rtx last_addr
= plus_constant (v
->dest_reg
,
2736 INTVAL (giv_inc
) * (unroll_number
- 1));
2738 /* First check to see if either address would fail. Handle the fact
2739 that we have may have a match_dup. */
2740 if (! validate_replace_rtx (*v
->location
, v
->dest_reg
, v
->insn
)
2741 || ! validate_replace_rtx (*v
->location
, last_addr
, v
->insn
))
2744 /* Now put things back the way they were before. This should always
2746 if (! validate_replace_rtx (*v
->location
, orig_addr
, v
->insn
))
2752 /* For every giv based on the biv BL, check to determine whether it is
2753 splittable. This is a subroutine to find_splittable_regs ().
2755 Return the number of instructions that set splittable registers. */
2758 find_splittable_givs (loop
, bl
, unroll_type
, increment
, unroll_number
)
2759 const struct loop
*loop
;
2760 struct iv_class
*bl
;
2761 enum unroll_types unroll_type
;
2765 struct induction
*v
, *v2
;
2770 /* Scan the list of givs, and set the same_insn field when there are
2771 multiple identical givs in the same insn. */
2772 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2773 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2774 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2778 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2782 /* Only split the giv if it has already been reduced, or if the loop is
2783 being completely unrolled. */
2784 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2787 /* The giv can be split if the insn that sets the giv is executed once
2788 and only once on every iteration of the loop. */
2789 /* An address giv can always be split. v->insn is just a use not a set,
2790 and hence it does not matter whether it is always executed. All that
2791 matters is that all the biv increments are always executed, and we
2792 won't reach here if they aren't. */
2793 if (v
->giv_type
!= DEST_ADDR
2794 && (! v
->always_computable
2795 || back_branch_in_range_p (loop
, v
->insn
)))
2798 /* The giv increment value must be a constant. */
2799 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2801 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2804 /* The loop must be unrolled completely, or else have a known number of
2805 iterations and only one exit, or else the giv must be dead outside
2806 the loop, or else the final value of the giv must be known.
2807 Otherwise, it is not safe to split the giv since it may not have the
2808 proper value on loop exit. */
2810 /* The used outside loop test will fail for DEST_ADDR givs. They are
2811 never used outside the loop anyways, so it is always safe to split a
2815 if (unroll_type
!= UNROLL_COMPLETELY
2816 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2817 && v
->giv_type
!= DEST_ADDR
2818 /* The next part is true if the pseudo is used outside the loop.
2819 We assume that this is true for any pseudo created after loop
2820 starts, because we don't have a reg_n_info entry for them. */
2821 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2822 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2823 /* Check for the case where the pseudo is set by a shift/add
2824 sequence, in which case the first insn setting the pseudo
2825 is the first insn of the shift/add sequence. */
2826 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2827 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2828 != INSN_UID (XEXP (tem
, 0)))))
2829 /* Line above always fails if INSN was moved by loop opt. */
2830 || (uid_luid
[REGNO_LAST_UID (REGNO (v
->dest_reg
))]
2831 >= INSN_LUID (loop
->end
)))
2832 /* Givs made from biv increments are missed by the above test, so
2833 test explicitly for them. */
2834 && (REGNO (v
->dest_reg
) < first_increment_giv
2835 || REGNO (v
->dest_reg
) > last_increment_giv
)
2836 && ! (final_value
= v
->final_value
))
2840 /* Currently, non-reduced/final-value givs are never split. */
2841 /* Should emit insns after the loop if possible, as the biv final value
2844 /* If the final value is non-zero, and the giv has not been reduced,
2845 then must emit an instruction to set the final value. */
2846 if (final_value
&& !v
->new_reg
)
2848 /* Create a new register to hold the value of the giv, and then set
2849 the giv to its final value before the loop start. The giv is set
2850 to its final value before loop start to ensure that this insn
2851 will always be executed, no matter how we exit. */
2852 tem
= gen_reg_rtx (v
->mode
);
2853 emit_insn_before (gen_move_insn (tem
, v
->dest_reg
), loop_start
);
2854 emit_insn_before (gen_move_insn (v
->dest_reg
, final_value
),
2857 if (loop_dump_stream
)
2858 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2859 REGNO (v
->dest_reg
), REGNO (tem
));
2865 /* This giv is splittable. If completely unrolling the loop, save the
2866 giv's initial value. Otherwise, save the constant zero for it. */
2868 if (unroll_type
== UNROLL_COMPLETELY
)
2870 /* It is not safe to use bl->initial_value here, because it may not
2871 be invariant. It is safe to use the initial value stored in
2872 the splittable_regs array if it is set. In rare cases, it won't
2873 be set, so then we do exactly the same thing as
2874 find_splittable_regs does to get a safe value. */
2875 rtx biv_initial_value
;
2877 if (splittable_regs
[bl
->regno
])
2878 biv_initial_value
= splittable_regs
[bl
->regno
];
2879 else if (GET_CODE (bl
->initial_value
) != REG
2880 || (REGNO (bl
->initial_value
) != bl
->regno
2881 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2882 biv_initial_value
= bl
->initial_value
;
2885 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2887 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2888 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2890 biv_initial_value
= tem
;
2892 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2893 v
->add_val
, v
->mode
);
2900 /* If a giv was combined with another giv, then we can only split
2901 this giv if the giv it was combined with was reduced. This
2902 is because the value of v->new_reg is meaningless in this
2904 if (v
->same
&& ! v
->same
->new_reg
)
2906 if (loop_dump_stream
)
2907 fprintf (loop_dump_stream
,
2908 "giv combined with unreduced giv not split.\n");
2911 /* If the giv is an address destination, it could be something other
2912 than a simple register, these have to be treated differently. */
2913 else if (v
->giv_type
== DEST_REG
)
2915 /* If value is not a constant, register, or register plus
2916 constant, then compute its value into a register before
2917 loop start. This prevents invalid rtx sharing, and should
2918 generate better code. We can use bl->initial_value here
2919 instead of splittable_regs[bl->regno] because this code
2920 is going before the loop start. */
2921 if (unroll_type
== UNROLL_COMPLETELY
2922 && GET_CODE (value
) != CONST_INT
2923 && GET_CODE (value
) != REG
2924 && (GET_CODE (value
) != PLUS
2925 || GET_CODE (XEXP (value
, 0)) != REG
2926 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2928 rtx tem
= gen_reg_rtx (v
->mode
);
2929 record_base_value (REGNO (tem
), v
->add_val
, 0);
2930 emit_iv_add_mult (bl
->initial_value
, v
->mult_val
,
2931 v
->add_val
, tem
, loop
->start
);
2935 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2936 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
2940 /* Splitting address givs is useful since it will often allow us
2941 to eliminate some increment insns for the base giv as
2944 /* If the addr giv is combined with a dest_reg giv, then all
2945 references to that dest reg will be remapped, which is NOT
2946 what we want for split addr regs. We always create a new
2947 register for the split addr giv, just to be safe. */
2949 /* If we have multiple identical address givs within a
2950 single instruction, then use a single pseudo reg for
2951 both. This is necessary in case one is a match_dup
2954 v
->const_adjust
= 0;
2958 v
->dest_reg
= v
->same_insn
->dest_reg
;
2959 if (loop_dump_stream
)
2960 fprintf (loop_dump_stream
,
2961 "Sharing address givs in insn %d\n",
2962 INSN_UID (v
->insn
));
2964 /* If multiple address GIVs have been combined with the
2965 same dest_reg GIV, do not create a new register for
2967 else if (unroll_type
!= UNROLL_COMPLETELY
2968 && v
->giv_type
== DEST_ADDR
2969 && v
->same
&& v
->same
->giv_type
== DEST_ADDR
2970 && v
->same
->unrolled
2971 /* combine_givs_p may return true for some cases
2972 where the add and mult values are not equal.
2973 To share a register here, the values must be
2975 && rtx_equal_p (v
->same
->mult_val
, v
->mult_val
)
2976 && rtx_equal_p (v
->same
->add_val
, v
->add_val
)
2977 /* If the memory references have different modes,
2978 then the address may not be valid and we must
2979 not share registers. */
2980 && verify_addresses (v
, giv_inc
, unroll_number
))
2982 v
->dest_reg
= v
->same
->dest_reg
;
2985 else if (unroll_type
!= UNROLL_COMPLETELY
)
2987 /* If not completely unrolling the loop, then create a new
2988 register to hold the split value of the DEST_ADDR giv.
2989 Emit insn to initialize its value before loop start. */
2991 rtx tem
= gen_reg_rtx (v
->mode
);
2992 struct induction
*same
= v
->same
;
2993 rtx new_reg
= v
->new_reg
;
2994 record_base_value (REGNO (tem
), v
->add_val
, 0);
2996 if (same
&& same
->derived_from
)
2998 /* calculate_giv_inc doesn't work for derived givs.
2999 copy_loop_body works around the problem for the
3000 DEST_REG givs themselves, but it can't handle
3001 DEST_ADDR givs that have been combined with
3002 a derived DEST_REG giv.
3003 So Handle V as if the giv from which V->SAME has
3004 been derived has been combined with V.
3005 recombine_givs only derives givs from givs that
3006 are reduced the ordinary, so we need not worry
3007 about same->derived_from being in turn derived. */
3009 same
= same
->derived_from
;
3010 new_reg
= express_from (same
, v
);
3011 new_reg
= replace_rtx (new_reg
, same
->dest_reg
,
3015 /* If the address giv has a constant in its new_reg value,
3016 then this constant can be pulled out and put in value,
3017 instead of being part of the initialization code. */
3019 if (GET_CODE (new_reg
) == PLUS
3020 && GET_CODE (XEXP (new_reg
, 1)) == CONST_INT
)
3023 = plus_constant (tem
, INTVAL (XEXP (new_reg
, 1)));
3025 /* Only succeed if this will give valid addresses.
3026 Try to validate both the first and the last
3027 address resulting from loop unrolling, if
3028 one fails, then can't do const elim here. */
3029 if (verify_addresses (v
, giv_inc
, unroll_number
))
3031 /* Save the negative of the eliminated const, so
3032 that we can calculate the dest_reg's increment
3034 v
->const_adjust
= - INTVAL (XEXP (new_reg
, 1));
3036 new_reg
= XEXP (new_reg
, 0);
3037 if (loop_dump_stream
)
3038 fprintf (loop_dump_stream
,
3039 "Eliminating constant from giv %d\n",
3048 /* If the address hasn't been checked for validity yet, do so
3049 now, and fail completely if either the first or the last
3050 unrolled copy of the address is not a valid address
3051 for the instruction that uses it. */
3052 if (v
->dest_reg
== tem
3053 && ! verify_addresses (v
, giv_inc
, unroll_number
))
3055 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3056 if (v2
->same_insn
== v
)
3059 if (loop_dump_stream
)
3060 fprintf (loop_dump_stream
,
3061 "Invalid address for giv at insn %d\n",
3062 INSN_UID (v
->insn
));
3066 v
->new_reg
= new_reg
;
3069 /* We set this after the address check, to guarantee that
3070 the register will be initialized. */
3073 /* To initialize the new register, just move the value of
3074 new_reg into it. This is not guaranteed to give a valid
3075 instruction on machines with complex addressing modes.
3076 If we can't recognize it, then delete it and emit insns
3077 to calculate the value from scratch. */
3078 emit_insn_before (gen_rtx_SET (VOIDmode
, tem
,
3079 copy_rtx (v
->new_reg
)),
3081 if (recog_memoized (PREV_INSN (loop
->start
)) < 0)
3085 /* We can't use bl->initial_value to compute the initial
3086 value, because the loop may have been preconditioned.
3087 We must calculate it from NEW_REG. Try using
3088 force_operand instead of emit_iv_add_mult. */
3089 delete_insn (PREV_INSN (loop
->start
));
3092 ret
= force_operand (v
->new_reg
, tem
);
3094 emit_move_insn (tem
, ret
);
3095 sequence
= gen_sequence ();
3097 emit_insn_before (sequence
, loop
->start
);
3099 if (loop_dump_stream
)
3100 fprintf (loop_dump_stream
,
3101 "Invalid init insn, rewritten.\n");
3106 v
->dest_reg
= value
;
3108 /* Check the resulting address for validity, and fail
3109 if the resulting address would be invalid. */
3110 if (! verify_addresses (v
, giv_inc
, unroll_number
))
3112 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3113 if (v2
->same_insn
== v
)
3116 if (loop_dump_stream
)
3117 fprintf (loop_dump_stream
,
3118 "Invalid address for giv at insn %d\n",
3119 INSN_UID (v
->insn
));
3122 if (v
->same
&& v
->same
->derived_from
)
3124 /* Handle V as if the giv from which V->SAME has
3125 been derived has been combined with V. */
3127 v
->same
= v
->same
->derived_from
;
3128 v
->new_reg
= express_from (v
->same
, v
);
3129 v
->new_reg
= replace_rtx (v
->new_reg
, v
->same
->dest_reg
,
3135 /* Store the value of dest_reg into the insn. This sharing
3136 will not be a problem as this insn will always be copied
3139 *v
->location
= v
->dest_reg
;
3141 /* If this address giv is combined with a dest reg giv, then
3142 save the base giv's induction pointer so that we will be
3143 able to handle this address giv properly. The base giv
3144 itself does not have to be splittable. */
3146 if (v
->same
&& v
->same
->giv_type
== DEST_REG
)
3147 addr_combined_regs
[REGNO (v
->same
->new_reg
)] = v
->same
;
3149 if (GET_CODE (v
->new_reg
) == REG
)
3151 /* This giv maybe hasn't been combined with any others.
3152 Make sure that it's giv is marked as splittable here. */
3154 splittable_regs
[REGNO (v
->new_reg
)] = value
;
3155 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
3157 /* Make it appear to depend upon itself, so that the
3158 giv will be properly split in the main loop above. */
3162 addr_combined_regs
[REGNO (v
->new_reg
)] = v
;
3166 if (loop_dump_stream
)
3167 fprintf (loop_dump_stream
, "DEST_ADDR giv being split.\n");
3173 /* Currently, unreduced giv's can't be split. This is not too much
3174 of a problem since unreduced giv's are not live across loop
3175 iterations anyways. When unrolling a loop completely though,
3176 it makes sense to reduce&split givs when possible, as this will
3177 result in simpler instructions, and will not require that a reg
3178 be live across loop iterations. */
3180 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
3181 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
3182 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
3188 /* Unreduced givs are only updated once by definition. Reduced givs
3189 are updated as many times as their biv is. Mark it so if this is
3190 a splittable register. Don't need to do anything for address givs
3191 where this may not be a register. */
3193 if (GET_CODE (v
->new_reg
) == REG
)
3197 count
= reg_biv_class
[REGNO (v
->src_reg
)]->biv_count
;
3199 if (count
> 1 && v
->derived_from
)
3200 /* In this case, there is one set where the giv insn was and one
3201 set each after each biv increment. (Most are likely dead.) */
3204 splittable_regs_updates
[REGNO (v
->new_reg
)] = count
;
3209 if (loop_dump_stream
)
3213 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
3215 else if (GET_CODE (v
->dest_reg
) != REG
)
3216 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
3218 regnum
= REGNO (v
->dest_reg
);
3219 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
3220 regnum
, INSN_UID (v
->insn
));
3227 /* Try to prove that the register is dead after the loop exits. Trace every
3228 loop exit looking for an insn that will always be executed, which sets
3229 the register to some value, and appears before the first use of the register
3230 is found. If successful, then return 1, otherwise return 0. */
3232 /* ?? Could be made more intelligent in the handling of jumps, so that
3233 it can search past if statements and other similar structures. */
3236 reg_dead_after_loop (loop
, reg
)
3237 const struct loop
*loop
;
3243 int label_count
= 0;
3245 /* In addition to checking all exits of this loop, we must also check
3246 all exits of inner nested loops that would exit this loop. We don't
3247 have any way to identify those, so we just give up if there are any
3248 such inner loop exits. */
3250 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
3253 if (label_count
!= loop
->exit_count
)
3256 /* HACK: Must also search the loop fall through exit, create a label_ref
3257 here which points to the loop->end, and append the loop_number_exit_labels
3259 label
= gen_rtx_LABEL_REF (VOIDmode
, loop
->end
);
3260 LABEL_NEXTREF (label
) = loop
->exit_labels
;
3262 for ( ; label
; label
= LABEL_NEXTREF (label
))
3264 /* Succeed if find an insn which sets the biv or if reach end of
3265 function. Fail if find an insn that uses the biv, or if come to
3266 a conditional jump. */
3268 insn
= NEXT_INSN (XEXP (label
, 0));
3271 code
= GET_CODE (insn
);
3272 if (GET_RTX_CLASS (code
) == 'i')
3276 if (reg_referenced_p (reg
, PATTERN (insn
)))
3279 set
= single_set (insn
);
3280 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
3284 if (code
== JUMP_INSN
)
3286 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3288 else if (! simplejump_p (insn
)
3289 /* Prevent infinite loop following infinite loops. */
3290 || jump_count
++ > 20)
3293 insn
= JUMP_LABEL (insn
);
3296 insn
= NEXT_INSN (insn
);
3300 /* Success, the register is dead on all loop exits. */
3304 /* Try to calculate the final value of the biv, the value it will have at
3305 the end of the loop. If we can do it, return that value. */
3308 final_biv_value (loop
, bl
)
3309 const struct loop
*loop
;
3310 struct iv_class
*bl
;
3312 rtx loop_end
= loop
->end
;
3313 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3316 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3318 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3321 /* The final value for reversed bivs must be calculated differently than
3322 for ordinary bivs. In this case, there is already an insn after the
3323 loop which sets this biv's final value (if necessary), and there are
3324 no other loop exits, so we can return any value. */
3327 if (loop_dump_stream
)
3328 fprintf (loop_dump_stream
,
3329 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3334 /* Try to calculate the final value as initial value + (number of iterations
3335 * increment). For this to work, increment must be invariant, the only
3336 exit from the loop must be the fall through at the bottom (otherwise
3337 it may not have its final value when the loop exits), and the initial
3338 value of the biv must be invariant. */
3340 if (n_iterations
!= 0
3341 && ! loop
->exit_count
3342 && loop_invariant_p (loop
, bl
->initial_value
))
3344 increment
= biv_total_increment (bl
);
3346 if (increment
&& loop_invariant_p (loop
, increment
))
3348 /* Can calculate the loop exit value, emit insns after loop
3349 end to calculate this value into a temporary register in
3350 case it is needed later. */
3352 tem
= gen_reg_rtx (bl
->biv
->mode
);
3353 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3354 /* Make sure loop_end is not the last insn. */
3355 if (NEXT_INSN (loop_end
) == 0)
3356 emit_note_after (NOTE_INSN_DELETED
, loop_end
);
3357 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3358 bl
->initial_value
, tem
, NEXT_INSN (loop_end
));
3360 if (loop_dump_stream
)
3361 fprintf (loop_dump_stream
,
3362 "Final biv value for %d, calculated.\n", bl
->regno
);
3368 /* Check to see if the biv is dead at all loop exits. */
3369 if (reg_dead_after_loop (loop
, bl
->biv
->src_reg
))
3371 if (loop_dump_stream
)
3372 fprintf (loop_dump_stream
,
3373 "Final biv value for %d, biv dead after loop exit.\n",
3382 /* Try to calculate the final value of the giv, the value it will have at
3383 the end of the loop. If we can do it, return that value. */
3386 final_giv_value (loop
, v
)
3387 const struct loop
*loop
;
3388 struct induction
*v
;
3390 struct iv_class
*bl
;
3393 rtx insert_before
, seq
;
3394 rtx loop_end
= loop
->end
;
3395 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3397 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
3399 /* The final value for givs which depend on reversed bivs must be calculated
3400 differently than for ordinary givs. In this case, there is already an
3401 insn after the loop which sets this giv's final value (if necessary),
3402 and there are no other loop exits, so we can return any value. */
3405 if (loop_dump_stream
)
3406 fprintf (loop_dump_stream
,
3407 "Final giv value for %d, depends on reversed biv\n",
3408 REGNO (v
->dest_reg
));
3412 /* Try to calculate the final value as a function of the biv it depends
3413 upon. The only exit from the loop must be the fall through at the bottom
3414 (otherwise it may not have its final value when the loop exits). */
3416 /* ??? Can calculate the final giv value by subtracting off the
3417 extra biv increments times the giv's mult_val. The loop must have
3418 only one exit for this to work, but the loop iterations does not need
3421 if (n_iterations
!= 0
3422 && ! loop
->exit_count
)
3424 /* ?? It is tempting to use the biv's value here since these insns will
3425 be put after the loop, and hence the biv will have its final value
3426 then. However, this fails if the biv is subsequently eliminated.
3427 Perhaps determine whether biv's are eliminable before trying to
3428 determine whether giv's are replaceable so that we can use the
3429 biv value here if it is not eliminable. */
3431 /* We are emitting code after the end of the loop, so we must make
3432 sure that bl->initial_value is still valid then. It will still
3433 be valid if it is invariant. */
3435 increment
= biv_total_increment (bl
);
3437 if (increment
&& loop_invariant_p (loop
, increment
)
3438 && loop_invariant_p (loop
, bl
->initial_value
))
3440 /* Can calculate the loop exit value of its biv as
3441 (n_iterations * increment) + initial_value */
3443 /* The loop exit value of the giv is then
3444 (final_biv_value - extra increments) * mult_val + add_val.
3445 The extra increments are any increments to the biv which
3446 occur in the loop after the giv's value is calculated.
3447 We must search from the insn that sets the giv to the end
3448 of the loop to calculate this value. */
3450 insert_before
= NEXT_INSN (loop_end
);
3452 /* Put the final biv value in tem. */
3453 tem
= gen_reg_rtx (bl
->biv
->mode
);
3454 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3455 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3456 bl
->initial_value
, tem
, insert_before
);
3458 /* Subtract off extra increments as we find them. */
3459 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3460 insn
= NEXT_INSN (insn
))
3462 struct induction
*biv
;
3464 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3465 if (biv
->insn
== insn
)
3468 tem
= expand_binop (GET_MODE (tem
), sub_optab
, tem
,
3469 biv
->add_val
, NULL_RTX
, 0,
3471 seq
= gen_sequence ();
3473 emit_insn_before (seq
, insert_before
);
3477 /* Now calculate the giv's final value. */
3478 emit_iv_add_mult (tem
, v
->mult_val
, v
->add_val
, tem
,
3481 if (loop_dump_stream
)
3482 fprintf (loop_dump_stream
,
3483 "Final giv value for %d, calc from biv's value.\n",
3484 REGNO (v
->dest_reg
));
3490 /* Replaceable giv's should never reach here. */
3494 /* Check to see if the biv is dead at all loop exits. */
3495 if (reg_dead_after_loop (loop
, v
->dest_reg
))
3497 if (loop_dump_stream
)
3498 fprintf (loop_dump_stream
,
3499 "Final giv value for %d, giv dead after loop exit.\n",
3500 REGNO (v
->dest_reg
));
3509 /* Look back before LOOP->START for then insn that sets REG and return
3510 the equivalent constant if there is a REG_EQUAL note otherwise just
3511 the SET_SRC of REG. */
3514 loop_find_equiv_value (loop
, reg
)
3515 const struct loop
*loop
;
3518 rtx loop_start
= loop
->start
;
3523 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3525 if (GET_CODE (insn
) == CODE_LABEL
)
3528 else if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i'
3529 && reg_set_p (reg
, insn
))
3531 /* We found the last insn before the loop that sets the register.
3532 If it sets the entire register, and has a REG_EQUAL note,
3533 then use the value of the REG_EQUAL note. */
3534 if ((set
= single_set (insn
))
3535 && (SET_DEST (set
) == reg
))
3537 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3539 /* Only use the REG_EQUAL note if it is a constant.
3540 Other things, divide in particular, will cause
3541 problems later if we use them. */
3542 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3543 && CONSTANT_P (XEXP (note
, 0)))
3544 ret
= XEXP (note
, 0);
3546 ret
= SET_SRC (set
);
3554 /* Return a simplified rtx for the expression OP - REG.
3556 REG must appear in OP, and OP must be a register or the sum of a register
3559 Thus, the return value must be const0_rtx or the second term.
3561 The caller is responsible for verifying that REG appears in OP and OP has
3565 subtract_reg_term (op
, reg
)
3570 if (GET_CODE (op
) == PLUS
)
3572 if (XEXP (op
, 0) == reg
)
3573 return XEXP (op
, 1);
3574 else if (XEXP (op
, 1) == reg
)
3575 return XEXP (op
, 0);
3577 /* OP does not contain REG as a term. */
3582 /* Find and return register term common to both expressions OP0 and
3583 OP1 or NULL_RTX if no such term exists. Each expression must be a
3584 REG or a PLUS of a REG. */
3587 find_common_reg_term (op0
, op1
)
3590 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3591 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3598 if (GET_CODE (op0
) == PLUS
)
3599 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3601 op01
= const0_rtx
, op00
= op0
;
3603 if (GET_CODE (op1
) == PLUS
)
3604 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3606 op11
= const0_rtx
, op10
= op1
;
3608 /* Find and return common register term if present. */
3609 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3611 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3615 /* No common register term found. */
3619 /* Calculate the number of loop iterations. Returns the exact number of loop
3620 iterations if it can be calculated, otherwise returns zero. */
3622 unsigned HOST_WIDE_INT
3623 loop_iterations (loop
)
3626 rtx comparison
, comparison_value
;
3627 rtx iteration_var
, initial_value
, increment
, final_value
;
3628 enum rtx_code comparison_code
;
3629 HOST_WIDE_INT abs_inc
;
3630 unsigned HOST_WIDE_INT abs_diff
;
3633 int unsigned_p
, compare_dir
, final_larger
;
3636 struct loop_info
*loop_info
= LOOP_INFO (loop
);
3638 loop_info
->n_iterations
= 0;
3639 loop_info
->initial_value
= 0;
3640 loop_info
->initial_equiv_value
= 0;
3641 loop_info
->comparison_value
= 0;
3642 loop_info
->final_value
= 0;
3643 loop_info
->final_equiv_value
= 0;
3644 loop_info
->increment
= 0;
3645 loop_info
->iteration_var
= 0;
3646 loop_info
->unroll_number
= 1;
3648 /* We used to use prev_nonnote_insn here, but that fails because it might
3649 accidentally get the branch for a contained loop if the branch for this
3650 loop was deleted. We can only trust branches immediately before the
3652 last_loop_insn
= PREV_INSN (loop
->end
);
3654 /* ??? We should probably try harder to find the jump insn
3655 at the end of the loop. The following code assumes that
3656 the last loop insn is a jump to the top of the loop. */
3657 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3659 if (loop_dump_stream
)
3660 fprintf (loop_dump_stream
,
3661 "Loop iterations: No final conditional branch found.\n");
3665 /* If there is a more than a single jump to the top of the loop
3666 we cannot (easily) determine the iteration count. */
3667 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3669 if (loop_dump_stream
)
3670 fprintf (loop_dump_stream
,
3671 "Loop iterations: Loop has multiple back edges.\n");
3675 /* Find the iteration variable. If the last insn is a conditional
3676 branch, and the insn before tests a register value, make that the
3677 iteration variable. */
3679 comparison
= get_condition_for_loop (loop
, last_loop_insn
);
3680 if (comparison
== 0)
3682 if (loop_dump_stream
)
3683 fprintf (loop_dump_stream
,
3684 "Loop iterations: No final comparison found.\n");
3688 /* ??? Get_condition may switch position of induction variable and
3689 invariant register when it canonicalizes the comparison. */
3691 comparison_code
= GET_CODE (comparison
);
3692 iteration_var
= XEXP (comparison
, 0);
3693 comparison_value
= XEXP (comparison
, 1);
3695 if (GET_CODE (iteration_var
) != REG
)
3697 if (loop_dump_stream
)
3698 fprintf (loop_dump_stream
,
3699 "Loop iterations: Comparison not against register.\n");
3703 /* The only new registers that are created before loop iterations
3704 are givs made from biv increments or registers created by
3705 load_mems. In the latter case, it is possible that try_copy_prop
3706 will propagate a new pseudo into the old iteration register but
3707 this will be marked by having the REG_USERVAR_P bit set. */
3709 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
3710 && ! REG_USERVAR_P (iteration_var
))
3713 iteration_info (loop
, iteration_var
, &initial_value
, &increment
);
3715 if (initial_value
== 0)
3716 /* iteration_info already printed a message. */
3721 switch (comparison_code
)
3736 /* Cannot determine loop iterations with this case. */
3755 /* If the comparison value is an invariant register, then try to find
3756 its value from the insns before the start of the loop. */
3758 final_value
= comparison_value
;
3759 if (GET_CODE (comparison_value
) == REG
3760 && loop_invariant_p (loop
, comparison_value
))
3762 final_value
= loop_find_equiv_value (loop
, comparison_value
);
3764 /* If we don't get an invariant final value, we are better
3765 off with the original register. */
3766 if (! loop_invariant_p (loop
, final_value
))
3767 final_value
= comparison_value
;
3770 /* Calculate the approximate final value of the induction variable
3771 (on the last successful iteration). The exact final value
3772 depends on the branch operator, and increment sign. It will be
3773 wrong if the iteration variable is not incremented by one each
3774 time through the loop and (comparison_value + off_by_one -
3775 initial_value) % increment != 0.
3776 ??? Note that the final_value may overflow and thus final_larger
3777 will be bogus. A potentially infinite loop will be classified
3778 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3780 final_value
= plus_constant (final_value
, off_by_one
);
3782 /* Save the calculated values describing this loop's bounds, in case
3783 precondition_loop_p will need them later. These values can not be
3784 recalculated inside precondition_loop_p because strength reduction
3785 optimizations may obscure the loop's structure.
3787 These values are only required by precondition_loop_p and insert_bct
3788 whenever the number of iterations cannot be computed at compile time.
3789 Only the difference between final_value and initial_value is
3790 important. Note that final_value is only approximate. */
3791 loop_info
->initial_value
= initial_value
;
3792 loop_info
->comparison_value
= comparison_value
;
3793 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3794 loop_info
->increment
= increment
;
3795 loop_info
->iteration_var
= iteration_var
;
3796 loop_info
->comparison_code
= comparison_code
;
3798 /* Try to determine the iteration count for loops such
3799 as (for i = init; i < init + const; i++). When running the
3800 loop optimization twice, the first pass often converts simple
3801 loops into this form. */
3803 if (REG_P (initial_value
))
3809 reg1
= initial_value
;
3810 if (GET_CODE (final_value
) == PLUS
)
3811 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3813 reg2
= final_value
, const2
= const0_rtx
;
3815 /* Check for initial_value = reg1, final_value = reg2 + const2,
3816 where reg1 != reg2. */
3817 if (REG_P (reg2
) && reg2
!= reg1
)
3821 /* Find what reg1 is equivalent to. Hopefully it will
3822 either be reg2 or reg2 plus a constant. */
3823 temp
= loop_find_equiv_value (loop
, reg1
);
3825 if (find_common_reg_term (temp
, reg2
))
3826 initial_value
= temp
;
3829 /* Find what reg2 is equivalent to. Hopefully it will
3830 either be reg1 or reg1 plus a constant. Let's ignore
3831 the latter case for now since it is not so common. */
3832 temp
= loop_find_equiv_value (loop
, reg2
);
3834 if (temp
== loop_info
->iteration_var
)
3835 temp
= initial_value
;
3837 final_value
= (const2
== const0_rtx
)
3838 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3841 else if (loop
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3845 /* When running the loop optimizer twice, check_dbra_loop
3846 further obfuscates reversible loops of the form:
3847 for (i = init; i < init + const; i++). We often end up with
3848 final_value = 0, initial_value = temp, temp = temp2 - init,
3849 where temp2 = init + const. If the loop has a vtop we
3850 can replace initial_value with const. */
3852 temp
= loop_find_equiv_value (loop
, reg1
);
3854 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3856 rtx temp2
= loop_find_equiv_value (loop
, XEXP (temp
, 0));
3858 if (GET_CODE (temp2
) == PLUS
3859 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3860 initial_value
= XEXP (temp2
, 1);
3865 /* If have initial_value = reg + const1 and final_value = reg +
3866 const2, then replace initial_value with const1 and final_value
3867 with const2. This should be safe since we are protected by the
3868 initial comparison before entering the loop if we have a vtop.
3869 For example, a + b < a + c is not equivalent to b < c for all a
3870 when using modulo arithmetic.
3872 ??? Without a vtop we could still perform the optimization if we check
3873 the initial and final values carefully. */
3875 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3877 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3878 final_value
= subtract_reg_term (final_value
, reg_term
);
3881 loop_info
->initial_equiv_value
= initial_value
;
3882 loop_info
->final_equiv_value
= final_value
;
3884 /* For EQ comparison loops, we don't have a valid final value.
3885 Check this now so that we won't leave an invalid value if we
3886 return early for any other reason. */
3887 if (comparison_code
== EQ
)
3888 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3892 if (loop_dump_stream
)
3893 fprintf (loop_dump_stream
,
3894 "Loop iterations: Increment value can't be calculated.\n");
3898 if (GET_CODE (increment
) != CONST_INT
)
3900 /* If we have a REG, check to see if REG holds a constant value. */
3901 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3902 clear if it is worthwhile to try to handle such RTL. */
3903 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3904 increment
= loop_find_equiv_value (loop
, increment
);
3906 if (GET_CODE (increment
) != CONST_INT
)
3908 if (loop_dump_stream
)
3910 fprintf (loop_dump_stream
,
3911 "Loop iterations: Increment value not constant ");
3912 print_rtl (loop_dump_stream
, increment
);
3913 fprintf (loop_dump_stream
, ".\n");
3917 loop_info
->increment
= increment
;
3920 if (GET_CODE (initial_value
) != CONST_INT
)
3922 if (loop_dump_stream
)
3924 fprintf (loop_dump_stream
,
3925 "Loop iterations: Initial value not constant ");
3926 print_rtl (loop_dump_stream
, initial_value
);
3927 fprintf (loop_dump_stream
, ".\n");
3931 else if (comparison_code
== EQ
)
3933 if (loop_dump_stream
)
3934 fprintf (loop_dump_stream
,
3935 "Loop iterations: EQ comparison loop.\n");
3938 else if (GET_CODE (final_value
) != CONST_INT
)
3940 if (loop_dump_stream
)
3942 fprintf (loop_dump_stream
,
3943 "Loop iterations: Final value not constant ");
3944 print_rtl (loop_dump_stream
, final_value
);
3945 fprintf (loop_dump_stream
, ".\n");
3950 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3953 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3954 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3955 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3956 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3958 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3959 - (INTVAL (final_value
) < INTVAL (initial_value
));
3961 if (INTVAL (increment
) > 0)
3963 else if (INTVAL (increment
) == 0)
3968 /* There are 27 different cases: compare_dir = -1, 0, 1;
3969 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3970 There are 4 normal cases, 4 reverse cases (where the iteration variable
3971 will overflow before the loop exits), 4 infinite loop cases, and 15
3972 immediate exit (0 or 1 iteration depending on loop type) cases.
3973 Only try to optimize the normal cases. */
3975 /* (compare_dir/final_larger/increment_dir)
3976 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3977 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3978 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3979 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3981 /* ?? If the meaning of reverse loops (where the iteration variable
3982 will overflow before the loop exits) is undefined, then could
3983 eliminate all of these special checks, and just always assume
3984 the loops are normal/immediate/infinite. Note that this means
3985 the sign of increment_dir does not have to be known. Also,
3986 since it does not really hurt if immediate exit loops or infinite loops
3987 are optimized, then that case could be ignored also, and hence all
3988 loops can be optimized.
3990 According to ANSI Spec, the reverse loop case result is undefined,
3991 because the action on overflow is undefined.
3993 See also the special test for NE loops below. */
3995 if (final_larger
== increment_dir
&& final_larger
!= 0
3996 && (final_larger
== compare_dir
|| compare_dir
== 0))
4001 if (loop_dump_stream
)
4002 fprintf (loop_dump_stream
,
4003 "Loop iterations: Not normal loop.\n");
4007 /* Calculate the number of iterations, final_value is only an approximation,
4008 so correct for that. Note that abs_diff and n_iterations are
4009 unsigned, because they can be as large as 2^n - 1. */
4011 abs_inc
= INTVAL (increment
);
4013 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
4014 else if (abs_inc
< 0)
4016 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
4022 /* For NE tests, make sure that the iteration variable won't miss
4023 the final value. If abs_diff mod abs_incr is not zero, then the
4024 iteration variable will overflow before the loop exits, and we
4025 can not calculate the number of iterations. */
4026 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
4029 /* Note that the number of iterations could be calculated using
4030 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
4031 handle potential overflow of the summation. */
4032 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
4033 return loop_info
->n_iterations
;
4037 /* Replace uses of split bivs with their split pseudo register. This is
4038 for original instructions which remain after loop unrolling without
4042 remap_split_bivs (x
)
4045 register enum rtx_code code
;
4047 register const char *fmt
;
4052 code
= GET_CODE (x
);
4067 /* If non-reduced/final-value givs were split, then this would also
4068 have to remap those givs also. */
4070 if (REGNO (x
) < max_reg_before_loop
4071 && REG_IV_TYPE (REGNO (x
)) == BASIC_INDUCT
)
4072 return reg_biv_class
[REGNO (x
)]->biv
->src_reg
;
4079 fmt
= GET_RTX_FORMAT (code
);
4080 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4083 XEXP (x
, i
) = remap_split_bivs (XEXP (x
, i
));
4084 else if (fmt
[i
] == 'E')
4087 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4088 XVECEXP (x
, i
, j
) = remap_split_bivs (XVECEXP (x
, i
, j
));
4094 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4095 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4096 return 0. COPY_START is where we can start looking for the insns
4097 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4100 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4101 must dominate LAST_UID.
4103 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4104 may not dominate LAST_UID.
4106 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4107 must dominate LAST_UID. */
4110 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
4117 int passed_jump
= 0;
4118 rtx p
= NEXT_INSN (copy_start
);
4120 while (INSN_UID (p
) != first_uid
)
4122 if (GET_CODE (p
) == JUMP_INSN
)
4124 /* Could not find FIRST_UID. */
4130 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4131 if (GET_RTX_CLASS (GET_CODE (p
)) != 'i'
4132 || ! dead_or_set_regno_p (p
, regno
))
4135 /* FIRST_UID is always executed. */
4136 if (passed_jump
== 0)
4139 while (INSN_UID (p
) != last_uid
)
4141 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4142 can not be sure that FIRST_UID dominates LAST_UID. */
4143 if (GET_CODE (p
) == CODE_LABEL
)
4145 /* Could not find LAST_UID, but we reached the end of the loop, so
4147 else if (p
== copy_end
)
4152 /* FIRST_UID is always executed if LAST_UID is executed. */