1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 93, 94, 95, 97, 98, 1999 Free Software Foundation, Inc.
3 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* Try to unroll a loop, and split induction variables.
24 Loops for which the number of iterations can be calculated exactly are
25 handled specially. If the number of iterations times the insn_count is
26 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
27 Otherwise, we try to unroll the loop a number of times modulo the number
28 of iterations, so that only one exit test will be needed. It is unrolled
29 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
32 Otherwise, if the number of iterations can be calculated exactly at
33 run time, and the loop is always entered at the top, then we try to
34 precondition the loop. That is, at run time, calculate how many times
35 the loop will execute, and then execute the loop body a few times so
36 that the remaining iterations will be some multiple of 4 (or 2 if the
37 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
38 with only one exit test needed at the end of the loop.
40 Otherwise, if the number of iterations can not be calculated exactly,
41 not even at run time, then we still unroll the loop a number of times
42 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
43 but there must be an exit test after each copy of the loop body.
45 For each induction variable, which is dead outside the loop (replaceable)
46 or for which we can easily calculate the final value, if we can easily
47 calculate its value at each place where it is set as a function of the
48 current loop unroll count and the variable's value at loop entry, then
49 the induction variable is split into `N' different variables, one for
50 each copy of the loop body. One variable is live across the backward
51 branch, and the others are all calculated as a function of this variable.
52 This helps eliminate data dependencies, and leads to further opportunities
55 /* Possible improvements follow: */
57 /* ??? Add an extra pass somewhere to determine whether unrolling will
58 give any benefit. E.g. after generating all unrolled insns, compute the
59 cost of all insns and compare against cost of insns in rolled loop.
61 - On traditional architectures, unrolling a non-constant bound loop
62 is a win if there is a giv whose only use is in memory addresses, the
63 memory addresses can be split, and hence giv increments can be
65 - It is also a win if the loop is executed many times, and preconditioning
66 can be performed for the loop.
67 Add code to check for these and similar cases. */
69 /* ??? Improve control of which loops get unrolled. Could use profiling
70 info to only unroll the most commonly executed loops. Perhaps have
71 a user specifyable option to control the amount of code expansion,
72 or the percent of loops to consider for unrolling. Etc. */
74 /* ??? Look at the register copies inside the loop to see if they form a
75 simple permutation. If so, iterate the permutation until it gets back to
76 the start state. This is how many times we should unroll the loop, for
77 best results, because then all register copies can be eliminated.
78 For example, the lisp nreverse function should be unrolled 3 times
87 ??? The number of times to unroll the loop may also be based on data
88 references in the loop. For example, if we have a loop that references
89 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
91 /* ??? Add some simple linear equation solving capability so that we can
92 determine the number of loop iterations for more complex loops.
93 For example, consider this loop from gdb
94 #define SWAP_TARGET_AND_HOST(buffer,len)
97 char *p = (char *) buffer;
98 char *q = ((char *) buffer) + len - 1;
99 int iterations = (len + 1) >> 1;
101 for (p; p < q; p++, q--;)
109 start value = p = &buffer + current_iteration
110 end value = q = &buffer + len - 1 - current_iteration
111 Given the loop exit test of "p < q", then there must be "q - p" iterations,
112 set equal to zero and solve for number of iterations:
113 q - p = len - 1 - 2*current_iteration = 0
114 current_iteration = (len - 1) / 2
115 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
116 iterations of this loop. */
118 /* ??? Currently, no labels are marked as loop invariant when doing loop
119 unrolling. This is because an insn inside the loop, that loads the address
120 of a label inside the loop into a register, could be moved outside the loop
121 by the invariant code motion pass if labels were invariant. If the loop
122 is subsequently unrolled, the code will be wrong because each unrolled
123 body of the loop will use the same address, whereas each actually needs a
124 different address. A case where this happens is when a loop containing
125 a switch statement is unrolled.
127 It would be better to let labels be considered invariant. When we
128 unroll loops here, check to see if any insns using a label local to the
129 loop were moved before the loop. If so, then correct the problem, by
130 moving the insn back into the loop, or perhaps replicate the insn before
131 the loop, one copy for each time the loop is unrolled. */
133 /* The prime factors looked for when trying to unroll a loop by some
134 number which is modulo the total number of iterations. Just checking
135 for these 4 prime factors will find at least one factor for 75% of
136 all numbers theoretically. Practically speaking, this will succeed
137 almost all of the time since loops are generally a multiple of 2
140 #define NUM_FACTORS 4
142 struct _factor
{ int factor
, count
; } factors
[NUM_FACTORS
]
143 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
145 /* Describes the different types of loop unrolling performed. */
147 enum unroll_types
{ UNROLL_COMPLETELY
, UNROLL_MODULO
, UNROLL_NAIVE
};
152 #include "insn-config.h"
153 #include "integrate.h"
157 #include "function.h"
162 /* This controls which loops are unrolled, and by how much we unroll
165 #ifndef MAX_UNROLLED_INSNS
166 #define MAX_UNROLLED_INSNS 100
169 /* Indexed by register number, if non-zero, then it contains a pointer
170 to a struct induction for a DEST_REG giv which has been combined with
171 one of more address givs. This is needed because whenever such a DEST_REG
172 giv is modified, we must modify the value of all split address givs
173 that were combined with this DEST_REG giv. */
175 static struct induction
**addr_combined_regs
;
177 /* Indexed by register number, if this is a splittable induction variable,
178 then this will hold the current value of the register, which depends on the
181 static rtx
*splittable_regs
;
183 /* Indexed by register number, if this is a splittable induction variable,
184 this indicates if it was made from a derived giv. */
185 static char *derived_regs
;
187 /* Indexed by register number, if this is a splittable induction variable,
188 then this will hold the number of instructions in the loop that modify
189 the induction variable. Used to ensure that only the last insn modifying
190 a split iv will update the original iv of the dest. */
192 static int *splittable_regs_updates
;
194 /* Forward declarations. */
196 static void init_reg_map
PROTO((struct inline_remap
*, int));
197 static rtx calculate_giv_inc
PROTO((rtx
, rtx
, int));
198 static rtx initial_reg_note_copy
PROTO((rtx
, struct inline_remap
*));
199 static void final_reg_note_copy
PROTO((rtx
, struct inline_remap
*));
200 static void copy_loop_body
PROTO((rtx
, rtx
, struct inline_remap
*, rtx
, int,
201 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
202 static void iteration_info
PROTO((rtx
, rtx
*, rtx
*, rtx
, rtx
));
203 static int find_splittable_regs
PROTO((enum unroll_types
, rtx
, rtx
, rtx
, int,
204 unsigned HOST_WIDE_INT
));
205 static int find_splittable_givs
PROTO((struct iv_class
*, enum unroll_types
,
206 rtx
, rtx
, rtx
, int));
207 static int reg_dead_after_loop
PROTO((rtx
, rtx
, rtx
));
208 static rtx fold_rtx_mult_add
PROTO((rtx
, rtx
, rtx
, enum machine_mode
));
209 static int verify_addresses
PROTO((struct induction
*, rtx
, int));
210 static rtx remap_split_bivs
PROTO((rtx
));
212 /* Try to unroll one loop and split induction variables in the loop.
214 The loop is described by the arguments LOOP_END, INSN_COUNT, and
215 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
216 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
217 indicates whether information generated in the strength reduction pass
220 This function is intended to be called from within `strength_reduce'
224 unroll_loop (loop_end
, insn_count
, loop_start
, end_insert_before
,
225 loop_info
, strength_reduce_p
)
229 rtx end_insert_before
;
230 struct loop_info
*loop_info
;
231 int strength_reduce_p
;
234 int unroll_number
= 1;
235 rtx copy_start
, copy_end
;
236 rtx insn
, sequence
, pattern
, tem
;
237 int max_labelno
, max_insnno
;
239 struct inline_remap
*map
;
240 char *local_label
= NULL
;
242 int max_local_regnum
;
247 int splitting_not_safe
= 0;
248 enum unroll_types unroll_type
;
249 int loop_preconditioned
= 0;
251 /* This points to the last real insn in the loop, which should be either
252 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
256 /* Don't bother unrolling huge loops. Since the minimum factor is
257 two, loops greater than one half of MAX_UNROLLED_INSNS will never
259 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
261 if (loop_dump_stream
)
262 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
266 /* When emitting debugger info, we can't unroll loops with unequal numbers
267 of block_beg and block_end notes, because that would unbalance the block
268 structure of the function. This can happen as a result of the
269 "if (foo) bar; else break;" optimization in jump.c. */
270 /* ??? Gcc has a general policy that -g is never supposed to change the code
271 that the compiler emits, so we must disable this optimization always,
272 even if debug info is not being output. This is rare, so this should
273 not be a significant performance problem. */
275 if (1 /* write_symbols != NO_DEBUG */)
277 int block_begins
= 0;
280 for (insn
= loop_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
282 if (GET_CODE (insn
) == NOTE
)
284 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
)
286 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
291 if (block_begins
!= block_ends
)
293 if (loop_dump_stream
)
294 fprintf (loop_dump_stream
,
295 "Unrolling failure: Unbalanced block notes.\n");
300 /* Determine type of unroll to perform. Depends on the number of iterations
301 and the size of the loop. */
303 /* If there is no strength reduce info, then set
304 loop_info->n_iterations to zero. This can happen if
305 strength_reduce can't find any bivs in the loop. A value of zero
306 indicates that the number of iterations could not be calculated. */
308 if (! strength_reduce_p
)
309 loop_info
->n_iterations
= 0;
311 if (loop_dump_stream
&& loop_info
->n_iterations
> 0)
313 fputs ("Loop unrolling: ", loop_dump_stream
);
314 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
315 loop_info
->n_iterations
);
316 fputs (" iterations.\n", loop_dump_stream
);
319 /* Find and save a pointer to the last nonnote insn in the loop. */
321 last_loop_insn
= prev_nonnote_insn (loop_end
);
323 /* Calculate how many times to unroll the loop. Indicate whether or
324 not the loop is being completely unrolled. */
326 if (loop_info
->n_iterations
== 1)
328 /* If number of iterations is exactly 1, then eliminate the compare and
329 branch at the end of the loop since they will never be taken.
330 Then return, since no other action is needed here. */
332 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
333 don't do anything. */
335 if (GET_CODE (last_loop_insn
) == BARRIER
)
337 /* Delete the jump insn. This will delete the barrier also. */
338 delete_insn (PREV_INSN (last_loop_insn
));
340 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
342 rtx prev
= PREV_INSN (last_loop_insn
);
343 delete_insn (last_loop_insn
);
345 /* The immediately preceding insn may be a compare which must be
347 if (sets_cc0_p (prev
))
353 else if (loop_info
->n_iterations
> 0
354 && loop_info
->n_iterations
* insn_count
< MAX_UNROLLED_INSNS
)
356 unroll_number
= loop_info
->n_iterations
;
357 unroll_type
= UNROLL_COMPLETELY
;
359 else if (loop_info
->n_iterations
> 0)
361 /* Try to factor the number of iterations. Don't bother with the
362 general case, only using 2, 3, 5, and 7 will get 75% of all
363 numbers theoretically, and almost all in practice. */
365 for (i
= 0; i
< NUM_FACTORS
; i
++)
366 factors
[i
].count
= 0;
368 temp
= loop_info
->n_iterations
;
369 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
370 while (temp
% factors
[i
].factor
== 0)
373 temp
= temp
/ factors
[i
].factor
;
376 /* Start with the larger factors first so that we generally
377 get lots of unrolling. */
381 for (i
= 3; i
>= 0; i
--)
382 while (factors
[i
].count
--)
384 if (temp
* factors
[i
].factor
< MAX_UNROLLED_INSNS
)
386 unroll_number
*= factors
[i
].factor
;
387 temp
*= factors
[i
].factor
;
393 /* If we couldn't find any factors, then unroll as in the normal
395 if (unroll_number
== 1)
397 if (loop_dump_stream
)
398 fprintf (loop_dump_stream
,
399 "Loop unrolling: No factors found.\n");
402 unroll_type
= UNROLL_MODULO
;
406 /* Default case, calculate number of times to unroll loop based on its
408 if (unroll_number
== 1)
410 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
412 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
417 unroll_type
= UNROLL_NAIVE
;
420 /* Now we know how many times to unroll the loop. */
422 if (loop_dump_stream
)
423 fprintf (loop_dump_stream
,
424 "Unrolling loop %d times.\n", unroll_number
);
427 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
429 /* Loops of these types can start with jump down to the exit condition
430 in rare circumstances.
432 Consider a pair of nested loops where the inner loop is part
433 of the exit code for the outer loop.
435 In this case jump.c will not duplicate the exit test for the outer
436 loop, so it will start with a jump to the exit code.
438 Then consider if the inner loop turns out to iterate once and
439 only once. We will end up deleting the jumps associated with
440 the inner loop. However, the loop notes are not removed from
441 the instruction stream.
443 And finally assume that we can compute the number of iterations
446 In this case unroll may want to unroll the outer loop even though
447 it starts with a jump to the outer loop's exit code.
449 We could try to optimize this case, but it hardly seems worth it.
450 Just return without unrolling the loop in such cases. */
453 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
454 insn
= NEXT_INSN (insn
);
455 if (GET_CODE (insn
) == JUMP_INSN
)
459 if (unroll_type
== UNROLL_COMPLETELY
)
461 /* Completely unrolling the loop: Delete the compare and branch at
462 the end (the last two instructions). This delete must done at the
463 very end of loop unrolling, to avoid problems with calls to
464 back_branch_in_range_p, which is called by find_splittable_regs.
465 All increments of splittable bivs/givs are changed to load constant
468 copy_start
= loop_start
;
470 /* Set insert_before to the instruction immediately after the JUMP_INSN
471 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
472 the loop will be correctly handled by copy_loop_body. */
473 insert_before
= NEXT_INSN (last_loop_insn
);
475 /* Set copy_end to the insn before the jump at the end of the loop. */
476 if (GET_CODE (last_loop_insn
) == BARRIER
)
477 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
478 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
480 copy_end
= PREV_INSN (last_loop_insn
);
482 /* The instruction immediately before the JUMP_INSN may be a compare
483 instruction which we do not want to copy. */
484 if (sets_cc0_p (PREV_INSN (copy_end
)))
485 copy_end
= PREV_INSN (copy_end
);
490 /* We currently can't unroll a loop if it doesn't end with a
491 JUMP_INSN. There would need to be a mechanism that recognizes
492 this case, and then inserts a jump after each loop body, which
493 jumps to after the last loop body. */
494 if (loop_dump_stream
)
495 fprintf (loop_dump_stream
,
496 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
500 else if (unroll_type
== UNROLL_MODULO
)
502 /* Partially unrolling the loop: The compare and branch at the end
503 (the last two instructions) must remain. Don't copy the compare
504 and branch instructions at the end of the loop. Insert the unrolled
505 code immediately before the compare/branch at the end so that the
506 code will fall through to them as before. */
508 copy_start
= loop_start
;
510 /* Set insert_before to the jump insn at the end of the loop.
511 Set copy_end to before the jump insn at the end of the loop. */
512 if (GET_CODE (last_loop_insn
) == BARRIER
)
514 insert_before
= PREV_INSN (last_loop_insn
);
515 copy_end
= PREV_INSN (insert_before
);
517 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
519 insert_before
= last_loop_insn
;
521 /* The instruction immediately before the JUMP_INSN may be a compare
522 instruction which we do not want to copy or delete. */
523 if (sets_cc0_p (PREV_INSN (insert_before
)))
524 insert_before
= PREV_INSN (insert_before
);
526 copy_end
= PREV_INSN (insert_before
);
530 /* We currently can't unroll a loop if it doesn't end with a
531 JUMP_INSN. There would need to be a mechanism that recognizes
532 this case, and then inserts a jump after each loop body, which
533 jumps to after the last loop body. */
534 if (loop_dump_stream
)
535 fprintf (loop_dump_stream
,
536 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
542 /* Normal case: Must copy the compare and branch instructions at the
545 if (GET_CODE (last_loop_insn
) == BARRIER
)
547 /* Loop ends with an unconditional jump and a barrier.
548 Handle this like above, don't copy jump and barrier.
549 This is not strictly necessary, but doing so prevents generating
550 unconditional jumps to an immediately following label.
552 This will be corrected below if the target of this jump is
553 not the start_label. */
555 insert_before
= PREV_INSN (last_loop_insn
);
556 copy_end
= PREV_INSN (insert_before
);
558 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
560 /* Set insert_before to immediately after the JUMP_INSN, so that
561 NOTEs at the end of the loop will be correctly handled by
563 insert_before
= NEXT_INSN (last_loop_insn
);
564 copy_end
= last_loop_insn
;
568 /* We currently can't unroll a loop if it doesn't end with a
569 JUMP_INSN. There would need to be a mechanism that recognizes
570 this case, and then inserts a jump after each loop body, which
571 jumps to after the last loop body. */
572 if (loop_dump_stream
)
573 fprintf (loop_dump_stream
,
574 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
578 /* If copying exit test branches because they can not be eliminated,
579 then must convert the fall through case of the branch to a jump past
580 the end of the loop. Create a label to emit after the loop and save
581 it for later use. Do not use the label after the loop, if any, since
582 it might be used by insns outside the loop, or there might be insns
583 added before it later by final_[bg]iv_value which must be after
584 the real exit label. */
585 exit_label
= gen_label_rtx ();
588 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
589 insn
= NEXT_INSN (insn
);
591 if (GET_CODE (insn
) == JUMP_INSN
)
593 /* The loop starts with a jump down to the exit condition test.
594 Start copying the loop after the barrier following this
596 copy_start
= NEXT_INSN (insn
);
598 /* Splitting induction variables doesn't work when the loop is
599 entered via a jump to the bottom, because then we end up doing
600 a comparison against a new register for a split variable, but
601 we did not execute the set insn for the new register because
602 it was skipped over. */
603 splitting_not_safe
= 1;
604 if (loop_dump_stream
)
605 fprintf (loop_dump_stream
,
606 "Splitting not safe, because loop not entered at top.\n");
609 copy_start
= loop_start
;
612 /* This should always be the first label in the loop. */
613 start_label
= NEXT_INSN (copy_start
);
614 /* There may be a line number note and/or a loop continue note here. */
615 while (GET_CODE (start_label
) == NOTE
)
616 start_label
= NEXT_INSN (start_label
);
617 if (GET_CODE (start_label
) != CODE_LABEL
)
619 /* This can happen as a result of jump threading. If the first insns in
620 the loop test the same condition as the loop's backward jump, or the
621 opposite condition, then the backward jump will be modified to point
622 to elsewhere, and the loop's start label is deleted.
624 This case currently can not be handled by the loop unrolling code. */
626 if (loop_dump_stream
)
627 fprintf (loop_dump_stream
,
628 "Unrolling failure: unknown insns between BEG note and loop label.\n");
631 if (LABEL_NAME (start_label
))
633 /* The jump optimization pass must have combined the original start label
634 with a named label for a goto. We can't unroll this case because
635 jumps which go to the named label must be handled differently than
636 jumps to the loop start, and it is impossible to differentiate them
638 if (loop_dump_stream
)
639 fprintf (loop_dump_stream
,
640 "Unrolling failure: loop start label is gone\n");
644 if (unroll_type
== UNROLL_NAIVE
645 && GET_CODE (last_loop_insn
) == BARRIER
646 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
648 /* In this case, we must copy the jump and barrier, because they will
649 not be converted to jumps to an immediately following label. */
651 insert_before
= NEXT_INSN (last_loop_insn
);
652 copy_end
= last_loop_insn
;
655 if (unroll_type
== UNROLL_NAIVE
656 && GET_CODE (last_loop_insn
) == JUMP_INSN
657 && start_label
!= JUMP_LABEL (last_loop_insn
))
659 /* ??? The loop ends with a conditional branch that does not branch back
660 to the loop start label. In this case, we must emit an unconditional
661 branch to the loop exit after emitting the final branch.
662 copy_loop_body does not have support for this currently, so we
663 give up. It doesn't seem worthwhile to unroll anyways since
664 unrolling would increase the number of branch instructions
666 if (loop_dump_stream
)
667 fprintf (loop_dump_stream
,
668 "Unrolling failure: final conditional branch not to loop start\n");
672 /* Allocate a translation table for the labels and insn numbers.
673 They will be filled in as we copy the insns in the loop. */
675 max_labelno
= max_label_num ();
676 max_insnno
= get_max_uid ();
678 map
= (struct inline_remap
*) alloca (sizeof (struct inline_remap
));
680 map
->integrating
= 0;
681 map
->const_equiv_varray
= 0;
683 /* Allocate the label map. */
687 map
->label_map
= (rtx
*) alloca (max_labelno
* sizeof (rtx
));
689 local_label
= (char *) alloca (max_labelno
);
690 bzero (local_label
, max_labelno
);
695 /* Search the loop and mark all local labels, i.e. the ones which have to
696 be distinct labels when copied. For all labels which might be
697 non-local, set their label_map entries to point to themselves.
698 If they happen to be local their label_map entries will be overwritten
699 before the loop body is copied. The label_map entries for local labels
700 will be set to a different value each time the loop body is copied. */
702 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
706 if (GET_CODE (insn
) == CODE_LABEL
)
707 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
708 else if (GET_CODE (insn
) == JUMP_INSN
)
710 if (JUMP_LABEL (insn
))
711 set_label_in_map (map
,
712 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)),
714 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
715 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
717 rtx pat
= PATTERN (insn
);
718 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
719 int len
= XVECLEN (pat
, diff_vec_p
);
722 for (i
= 0; i
< len
; i
++)
724 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
725 set_label_in_map (map
,
726 CODE_LABEL_NUMBER (label
),
731 else if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)))
732 set_label_in_map (map
, CODE_LABEL_NUMBER (XEXP (note
, 0)),
736 /* Allocate space for the insn map. */
738 map
->insn_map
= (rtx
*) alloca (max_insnno
* sizeof (rtx
));
740 /* Set this to zero, to indicate that we are doing loop unrolling,
741 not function inlining. */
742 map
->inline_target
= 0;
744 /* The register and constant maps depend on the number of registers
745 present, so the final maps can't be created until after
746 find_splittable_regs is called. However, they are needed for
747 preconditioning, so we create temporary maps when preconditioning
750 /* The preconditioning code may allocate two new pseudo registers. */
751 maxregnum
= max_reg_num ();
753 /* local_regno is only valid for regnos < max_local_regnum. */
754 max_local_regnum
= maxregnum
;
756 /* Allocate and zero out the splittable_regs and addr_combined_regs
757 arrays. These must be zeroed here because they will be used if
758 loop preconditioning is performed, and must be zero for that case.
760 It is safe to do this here, since the extra registers created by the
761 preconditioning code and find_splittable_regs will never be used
762 to access the splittable_regs[] and addr_combined_regs[] arrays. */
764 splittable_regs
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
765 bzero ((char *) splittable_regs
, maxregnum
* sizeof (rtx
));
766 derived_regs
= alloca (maxregnum
);
767 bzero (derived_regs
, maxregnum
);
768 splittable_regs_updates
= (int *) alloca (maxregnum
* sizeof (int));
769 bzero ((char *) splittable_regs_updates
, maxregnum
* sizeof (int));
771 = (struct induction
**) alloca (maxregnum
* sizeof (struct induction
*));
772 bzero ((char *) addr_combined_regs
, maxregnum
* sizeof (struct induction
*));
773 local_regno
= (char *) alloca (maxregnum
);
774 bzero (local_regno
, maxregnum
);
776 /* Mark all local registers, i.e. the ones which are referenced only
778 if (INSN_UID (copy_end
) < max_uid_for_loop
)
780 int copy_start_luid
= INSN_LUID (copy_start
);
781 int copy_end_luid
= INSN_LUID (copy_end
);
783 /* If a register is used in the jump insn, we must not duplicate it
784 since it will also be used outside the loop. */
785 if (GET_CODE (copy_end
) == JUMP_INSN
)
788 /* If we have a target that uses cc0, then we also must not duplicate
789 the insn that sets cc0 before the jump insn, if one is present. */
791 if (GET_CODE (copy_end
) == JUMP_INSN
&& sets_cc0_p (PREV_INSN (copy_end
)))
795 /* If copy_start points to the NOTE that starts the loop, then we must
796 use the next luid, because invariant pseudo-regs moved out of the loop
797 have their lifetimes modified to start here, but they are not safe
799 if (copy_start
== loop_start
)
802 /* If a pseudo's lifetime is entirely contained within this loop, then we
803 can use a different pseudo in each unrolled copy of the loop. This
804 results in better code. */
805 /* We must limit the generic test to max_reg_before_loop, because only
806 these pseudo registers have valid regno_first_uid info. */
807 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_reg_before_loop
; ++j
)
808 if (REGNO_FIRST_UID (j
) > 0 && REGNO_FIRST_UID (j
) <= max_uid_for_loop
809 && uid_luid
[REGNO_FIRST_UID (j
)] >= copy_start_luid
810 && REGNO_LAST_UID (j
) > 0 && REGNO_LAST_UID (j
) <= max_uid_for_loop
811 && uid_luid
[REGNO_LAST_UID (j
)] <= copy_end_luid
)
813 /* However, we must also check for loop-carried dependencies.
814 If the value the pseudo has at the end of iteration X is
815 used by iteration X+1, then we can not use a different pseudo
816 for each unrolled copy of the loop. */
817 /* A pseudo is safe if regno_first_uid is a set, and this
818 set dominates all instructions from regno_first_uid to
820 /* ??? This check is simplistic. We would get better code if
821 this check was more sophisticated. */
822 if (set_dominates_use (j
, REGNO_FIRST_UID (j
), REGNO_LAST_UID (j
),
823 copy_start
, copy_end
))
826 if (loop_dump_stream
)
829 fprintf (loop_dump_stream
, "Marked reg %d as local\n", j
);
831 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
835 /* Givs that have been created from multiple biv increments always have
837 for (j
= first_increment_giv
; j
<= last_increment_giv
; j
++)
840 if (loop_dump_stream
)
841 fprintf (loop_dump_stream
, "Marked reg %d as local\n", j
);
845 /* If this loop requires exit tests when unrolled, check to see if we
846 can precondition the loop so as to make the exit tests unnecessary.
847 Just like variable splitting, this is not safe if the loop is entered
848 via a jump to the bottom. Also, can not do this if no strength
849 reduce info, because precondition_loop_p uses this info. */
851 /* Must copy the loop body for preconditioning before the following
852 find_splittable_regs call since that will emit insns which need to
853 be after the preconditioned loop copies, but immediately before the
854 unrolled loop copies. */
856 /* Also, it is not safe to split induction variables for the preconditioned
857 copies of the loop body. If we split induction variables, then the code
858 assumes that each induction variable can be represented as a function
859 of its initial value and the loop iteration number. This is not true
860 in this case, because the last preconditioned copy of the loop body
861 could be any iteration from the first up to the `unroll_number-1'th,
862 depending on the initial value of the iteration variable. Therefore
863 we can not split induction variables here, because we can not calculate
864 their value. Hence, this code must occur before find_splittable_regs
867 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
869 rtx initial_value
, final_value
, increment
;
870 enum machine_mode mode
;
872 if (precondition_loop_p (loop_start
, loop_info
,
873 &initial_value
, &final_value
, &increment
,
878 int abs_inc
, neg_inc
;
880 map
->reg_map
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
882 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
, maxregnum
,
884 global_const_equiv_varray
= map
->const_equiv_varray
;
886 init_reg_map (map
, maxregnum
);
888 /* Limit loop unrolling to 4, since this will make 7 copies of
890 if (unroll_number
> 4)
893 /* Save the absolute value of the increment, and also whether or
894 not it is negative. */
896 abs_inc
= INTVAL (increment
);
905 /* Calculate the difference between the final and initial values.
906 Final value may be a (plus (reg x) (const_int 1)) rtx.
907 Let the following cse pass simplify this if initial value is
910 We must copy the final and initial values here to avoid
911 improperly shared rtl. */
913 diff
= expand_binop (mode
, sub_optab
, copy_rtx (final_value
),
914 copy_rtx (initial_value
), NULL_RTX
, 0,
917 /* Now calculate (diff % (unroll * abs (increment))) by using an
919 diff
= expand_binop (GET_MODE (diff
), and_optab
, diff
,
920 GEN_INT (unroll_number
* abs_inc
- 1),
921 NULL_RTX
, 0, OPTAB_LIB_WIDEN
);
923 /* Now emit a sequence of branches to jump to the proper precond
926 labels
= (rtx
*) alloca (sizeof (rtx
) * unroll_number
);
927 for (i
= 0; i
< unroll_number
; i
++)
928 labels
[i
] = gen_label_rtx ();
930 /* Check for the case where the initial value is greater than or
931 equal to the final value. In that case, we want to execute
932 exactly one loop iteration. The code below will fail for this
933 case. This check does not apply if the loop has a NE
934 comparison at the end. */
936 if (loop_info
->comparison_code
!= NE
)
938 emit_cmp_and_jump_insns (initial_value
, final_value
,
940 NULL_RTX
, mode
, 0, 0, labels
[1]);
941 JUMP_LABEL (get_last_insn ()) = labels
[1];
942 LABEL_NUSES (labels
[1])++;
945 /* Assuming the unroll_number is 4, and the increment is 2, then
946 for a negative increment: for a positive increment:
947 diff = 0,1 precond 0 diff = 0,7 precond 0
948 diff = 2,3 precond 3 diff = 1,2 precond 1
949 diff = 4,5 precond 2 diff = 3,4 precond 2
950 diff = 6,7 precond 1 diff = 5,6 precond 3 */
952 /* We only need to emit (unroll_number - 1) branches here, the
953 last case just falls through to the following code. */
955 /* ??? This would give better code if we emitted a tree of branches
956 instead of the current linear list of branches. */
958 for (i
= 0; i
< unroll_number
- 1; i
++)
961 enum rtx_code cmp_code
;
963 /* For negative increments, must invert the constant compared
964 against, except when comparing against zero. */
972 cmp_const
= unroll_number
- i
;
981 emit_cmp_and_jump_insns (diff
, GEN_INT (abs_inc
* cmp_const
),
982 cmp_code
, NULL_RTX
, mode
, 0, 0,
984 JUMP_LABEL (get_last_insn ()) = labels
[i
];
985 LABEL_NUSES (labels
[i
])++;
988 /* If the increment is greater than one, then we need another branch,
989 to handle other cases equivalent to 0. */
991 /* ??? This should be merged into the code above somehow to help
992 simplify the code here, and reduce the number of branches emitted.
993 For the negative increment case, the branch here could easily
994 be merged with the `0' case branch above. For the positive
995 increment case, it is not clear how this can be simplified. */
1000 enum rtx_code cmp_code
;
1004 cmp_const
= abs_inc
- 1;
1009 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
1013 emit_cmp_and_jump_insns (diff
, GEN_INT (cmp_const
), cmp_code
,
1014 NULL_RTX
, mode
, 0, 0, labels
[0]);
1015 JUMP_LABEL (get_last_insn ()) = labels
[0];
1016 LABEL_NUSES (labels
[0])++;
1019 sequence
= gen_sequence ();
1021 emit_insn_before (sequence
, loop_start
);
1023 /* Only the last copy of the loop body here needs the exit
1024 test, so set copy_end to exclude the compare/branch here,
1025 and then reset it inside the loop when get to the last
1028 if (GET_CODE (last_loop_insn
) == BARRIER
)
1029 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1030 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1032 copy_end
= PREV_INSN (last_loop_insn
);
1034 /* The immediately preceding insn may be a compare which we do not
1036 if (sets_cc0_p (PREV_INSN (copy_end
)))
1037 copy_end
= PREV_INSN (copy_end
);
1043 for (i
= 1; i
< unroll_number
; i
++)
1045 emit_label_after (labels
[unroll_number
- i
],
1046 PREV_INSN (loop_start
));
1048 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1049 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1050 (VARRAY_SIZE (map
->const_equiv_varray
)
1051 * sizeof (struct const_equiv_data
)));
1054 for (j
= 0; j
< max_labelno
; j
++)
1056 set_label_in_map (map
, j
, gen_label_rtx ());
1058 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_local_regnum
; j
++)
1061 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1062 record_base_value (REGNO (map
->reg_map
[j
]),
1063 regno_reg_rtx
[j
], 0);
1065 /* The last copy needs the compare/branch insns at the end,
1066 so reset copy_end here if the loop ends with a conditional
1069 if (i
== unroll_number
- 1)
1071 if (GET_CODE (last_loop_insn
) == BARRIER
)
1072 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1074 copy_end
= last_loop_insn
;
1077 /* None of the copies are the `last_iteration', so just
1078 pass zero for that parameter. */
1079 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, 0,
1080 unroll_type
, start_label
, loop_end
,
1081 loop_start
, copy_end
);
1083 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1085 if (GET_CODE (last_loop_insn
) == BARRIER
)
1087 insert_before
= PREV_INSN (last_loop_insn
);
1088 copy_end
= PREV_INSN (insert_before
);
1092 insert_before
= last_loop_insn
;
1094 /* The instruction immediately before the JUMP_INSN may be a compare
1095 instruction which we do not want to copy or delete. */
1096 if (sets_cc0_p (PREV_INSN (insert_before
)))
1097 insert_before
= PREV_INSN (insert_before
);
1099 copy_end
= PREV_INSN (insert_before
);
1102 /* Set unroll type to MODULO now. */
1103 unroll_type
= UNROLL_MODULO
;
1104 loop_preconditioned
= 1;
1108 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1109 the loop unless all loops are being unrolled. */
1110 if (unroll_type
== UNROLL_NAIVE
&& ! flag_unroll_all_loops
)
1112 if (loop_dump_stream
)
1113 fprintf (loop_dump_stream
, "Unrolling failure: Naive unrolling not being done.\n");
1117 /* At this point, we are guaranteed to unroll the loop. */
1119 /* Keep track of the unroll factor for the loop. */
1120 loop_info
->unroll_number
= unroll_number
;
1122 /* For each biv and giv, determine whether it can be safely split into
1123 a different variable for each unrolled copy of the loop body.
1124 We precalculate and save this info here, since computing it is
1127 Do this before deleting any instructions from the loop, so that
1128 back_branch_in_range_p will work correctly. */
1130 if (splitting_not_safe
)
1133 temp
= find_splittable_regs (unroll_type
, loop_start
, loop_end
,
1134 end_insert_before
, unroll_number
,
1135 loop_info
->n_iterations
);
1137 /* find_splittable_regs may have created some new registers, so must
1138 reallocate the reg_map with the new larger size, and must realloc
1139 the constant maps also. */
1141 maxregnum
= max_reg_num ();
1142 map
->reg_map
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
1144 init_reg_map (map
, maxregnum
);
1146 if (map
->const_equiv_varray
== 0)
1147 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1148 maxregnum
+ temp
* unroll_number
* 2,
1150 global_const_equiv_varray
= map
->const_equiv_varray
;
1152 /* Search the list of bivs and givs to find ones which need to be remapped
1153 when split, and set their reg_map entry appropriately. */
1155 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
1157 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1158 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1160 /* Currently, non-reduced/final-value givs are never split. */
1161 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1162 if (REGNO (v
->src_reg
) != bl
->regno
)
1163 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1167 /* Use our current register alignment and pointer flags. */
1168 map
->regno_pointer_flag
= current_function
->emit
->regno_pointer_flag
;
1169 map
->regno_pointer_align
= current_function
->emit
->regno_pointer_align
;
1171 /* If the loop is being partially unrolled, and the iteration variables
1172 are being split, and are being renamed for the split, then must fix up
1173 the compare/jump instruction at the end of the loop to refer to the new
1174 registers. This compare isn't copied, so the registers used in it
1175 will never be replaced if it isn't done here. */
1177 if (unroll_type
== UNROLL_MODULO
)
1179 insn
= NEXT_INSN (copy_end
);
1180 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1181 PATTERN (insn
) = remap_split_bivs (PATTERN (insn
));
1184 /* For unroll_number times, make a copy of each instruction
1185 between copy_start and copy_end, and insert these new instructions
1186 before the end of the loop. */
1188 for (i
= 0; i
< unroll_number
; i
++)
1190 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1191 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1192 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1195 for (j
= 0; j
< max_labelno
; j
++)
1197 set_label_in_map (map
, j
, gen_label_rtx ());
1199 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_local_regnum
; j
++)
1202 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1203 record_base_value (REGNO (map
->reg_map
[j
]),
1204 regno_reg_rtx
[j
], 0);
1207 /* If loop starts with a branch to the test, then fix it so that
1208 it points to the test of the first unrolled copy of the loop. */
1209 if (i
== 0 && loop_start
!= copy_start
)
1211 insn
= PREV_INSN (copy_start
);
1212 pattern
= PATTERN (insn
);
1214 tem
= get_label_from_map (map
,
1216 (XEXP (SET_SRC (pattern
), 0)));
1217 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1219 /* Set the jump label so that it can be used by later loop unrolling
1221 JUMP_LABEL (insn
) = tem
;
1222 LABEL_NUSES (tem
)++;
1225 copy_loop_body (copy_start
, copy_end
, map
, exit_label
,
1226 i
== unroll_number
- 1, unroll_type
, start_label
,
1227 loop_end
, insert_before
, insert_before
);
1230 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1231 insn to be deleted. This prevents any runaway delete_insn call from
1232 more insns that it should, as it always stops at a CODE_LABEL. */
1234 /* Delete the compare and branch at the end of the loop if completely
1235 unrolling the loop. Deleting the backward branch at the end also
1236 deletes the code label at the start of the loop. This is done at
1237 the very end to avoid problems with back_branch_in_range_p. */
1239 if (unroll_type
== UNROLL_COMPLETELY
)
1240 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1242 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1244 /* Delete all of the original loop instructions. Don't delete the
1245 LOOP_BEG note, or the first code label in the loop. */
1247 insn
= NEXT_INSN (copy_start
);
1248 while (insn
!= safety_label
)
1250 /* ??? Don't delete named code labels. They will be deleted when the
1251 jump that references them is deleted. Otherwise, we end up deleting
1252 them twice, which causes them to completely disappear instead of turn
1253 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1254 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1255 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1256 associated LABEL_DECL to point to one of the new label instances. */
1257 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1258 if (insn
!= start_label
1259 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1260 && ! (GET_CODE (insn
) == NOTE
1261 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1262 insn
= delete_insn (insn
);
1264 insn
= NEXT_INSN (insn
);
1267 /* Can now delete the 'safety' label emitted to protect us from runaway
1268 delete_insn calls. */
1269 if (INSN_DELETED_P (safety_label
))
1271 delete_insn (safety_label
);
1273 /* If exit_label exists, emit it after the loop. Doing the emit here
1274 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1275 This is needed so that mostly_true_jump in reorg.c will treat jumps
1276 to this loop end label correctly, i.e. predict that they are usually
1279 emit_label_after (exit_label
, loop_end
);
1282 if (map
&& map
->const_equiv_varray
)
1283 VARRAY_FREE (map
->const_equiv_varray
);
1286 /* Return true if the loop can be safely, and profitably, preconditioned
1287 so that the unrolled copies of the loop body don't need exit tests.
1289 This only works if final_value, initial_value and increment can be
1290 determined, and if increment is a constant power of 2.
1291 If increment is not a power of 2, then the preconditioning modulo
1292 operation would require a real modulo instead of a boolean AND, and this
1293 is not considered `profitable'. */
1295 /* ??? If the loop is known to be executed very many times, or the machine
1296 has a very cheap divide instruction, then preconditioning is a win even
1297 when the increment is not a power of 2. Use RTX_COST to compute
1298 whether divide is cheap.
1299 ??? A divide by constant doesn't actually need a divide, look at
1300 expand_divmod. The reduced cost of this optimized modulo is not
1301 reflected in RTX_COST. */
1304 precondition_loop_p (loop_start
, loop_info
,
1305 initial_value
, final_value
, increment
, mode
)
1307 struct loop_info
*loop_info
;
1308 rtx
*initial_value
, *final_value
, *increment
;
1309 enum machine_mode
*mode
;
1312 if (loop_info
->n_iterations
> 0)
1314 *initial_value
= const0_rtx
;
1315 *increment
= const1_rtx
;
1316 *final_value
= GEN_INT (loop_info
->n_iterations
);
1319 if (loop_dump_stream
)
1321 fputs ("Preconditioning: Success, number of iterations known, ",
1323 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
1324 loop_info
->n_iterations
);
1325 fputs (".\n", loop_dump_stream
);
1330 if (loop_info
->initial_value
== 0)
1332 if (loop_dump_stream
)
1333 fprintf (loop_dump_stream
,
1334 "Preconditioning: Could not find initial value.\n");
1337 else if (loop_info
->increment
== 0)
1339 if (loop_dump_stream
)
1340 fprintf (loop_dump_stream
,
1341 "Preconditioning: Could not find increment value.\n");
1344 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1346 if (loop_dump_stream
)
1347 fprintf (loop_dump_stream
,
1348 "Preconditioning: Increment not a constant.\n");
1351 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1352 && (exact_log2 (- INTVAL (loop_info
->increment
)) < 0))
1354 if (loop_dump_stream
)
1355 fprintf (loop_dump_stream
,
1356 "Preconditioning: Increment not a constant power of 2.\n");
1360 /* Unsigned_compare and compare_dir can be ignored here, since they do
1361 not matter for preconditioning. */
1363 if (loop_info
->final_value
== 0)
1365 if (loop_dump_stream
)
1366 fprintf (loop_dump_stream
,
1367 "Preconditioning: EQ comparison loop.\n");
1371 /* Must ensure that final_value is invariant, so call invariant_p to
1372 check. Before doing so, must check regno against max_reg_before_loop
1373 to make sure that the register is in the range covered by invariant_p.
1374 If it isn't, then it is most likely a biv/giv which by definition are
1376 if ((GET_CODE (loop_info
->final_value
) == REG
1377 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1378 || (GET_CODE (loop_info
->final_value
) == PLUS
1379 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1380 || ! invariant_p (loop_info
->final_value
))
1382 if (loop_dump_stream
)
1383 fprintf (loop_dump_stream
,
1384 "Preconditioning: Final value not invariant.\n");
1388 /* Fail for floating point values, since the caller of this function
1389 does not have code to deal with them. */
1390 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1391 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1393 if (loop_dump_stream
)
1394 fprintf (loop_dump_stream
,
1395 "Preconditioning: Floating point final or initial value.\n");
1399 /* Fail if loop_info->iteration_var is not live before loop_start,
1400 since we need to test its value in the preconditioning code. */
1402 if (uid_luid
[REGNO_FIRST_UID (REGNO (loop_info
->iteration_var
))]
1403 > INSN_LUID (loop_start
))
1405 if (loop_dump_stream
)
1406 fprintf (loop_dump_stream
,
1407 "Preconditioning: Iteration var not live before loop start.\n");
1411 /* Note that iteration_info biases the initial value for GIV iterators
1412 such as "while (i-- > 0)" so that we can calculate the number of
1413 iterations just like for BIV iterators.
1415 Also note that the absolute values of initial_value and
1416 final_value are unimportant as only their difference is used for
1417 calculating the number of loop iterations. */
1418 *initial_value
= loop_info
->initial_value
;
1419 *increment
= loop_info
->increment
;
1420 *final_value
= loop_info
->final_value
;
1422 /* Decide what mode to do these calculations in. Choose the larger
1423 of final_value's mode and initial_value's mode, or a full-word if
1424 both are constants. */
1425 *mode
= GET_MODE (*final_value
);
1426 if (*mode
== VOIDmode
)
1428 *mode
= GET_MODE (*initial_value
);
1429 if (*mode
== VOIDmode
)
1432 else if (*mode
!= GET_MODE (*initial_value
)
1433 && (GET_MODE_SIZE (*mode
)
1434 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1435 *mode
= GET_MODE (*initial_value
);
1438 if (loop_dump_stream
)
1439 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1444 /* All pseudo-registers must be mapped to themselves. Two hard registers
1445 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1446 REGNUM, to avoid function-inlining specific conversions of these
1447 registers. All other hard regs can not be mapped because they may be
1452 init_reg_map (map
, maxregnum
)
1453 struct inline_remap
*map
;
1458 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1459 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1460 /* Just clear the rest of the entries. */
1461 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1462 map
->reg_map
[i
] = 0;
1464 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1465 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1466 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1467 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1470 /* Strength-reduction will often emit code for optimized biv/givs which
1471 calculates their value in a temporary register, and then copies the result
1472 to the iv. This procedure reconstructs the pattern computing the iv;
1473 verifying that all operands are of the proper form.
1475 PATTERN must be the result of single_set.
1476 The return value is the amount that the giv is incremented by. */
1479 calculate_giv_inc (pattern
, src_insn
, regno
)
1480 rtx pattern
, src_insn
;
1484 rtx increment_total
= 0;
1488 /* Verify that we have an increment insn here. First check for a plus
1489 as the set source. */
1490 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1492 /* SR sometimes computes the new giv value in a temp, then copies it
1494 src_insn
= PREV_INSN (src_insn
);
1495 pattern
= PATTERN (src_insn
);
1496 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1499 /* The last insn emitted is not needed, so delete it to avoid confusing
1500 the second cse pass. This insn sets the giv unnecessarily. */
1501 delete_insn (get_last_insn ());
1504 /* Verify that we have a constant as the second operand of the plus. */
1505 increment
= XEXP (SET_SRC (pattern
), 1);
1506 if (GET_CODE (increment
) != CONST_INT
)
1508 /* SR sometimes puts the constant in a register, especially if it is
1509 too big to be an add immed operand. */
1510 src_insn
= PREV_INSN (src_insn
);
1511 increment
= SET_SRC (PATTERN (src_insn
));
1513 /* SR may have used LO_SUM to compute the constant if it is too large
1514 for a load immed operand. In this case, the constant is in operand
1515 one of the LO_SUM rtx. */
1516 if (GET_CODE (increment
) == LO_SUM
)
1517 increment
= XEXP (increment
, 1);
1519 /* Some ports store large constants in memory and add a REG_EQUAL
1520 note to the store insn. */
1521 else if (GET_CODE (increment
) == MEM
)
1523 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1525 increment
= XEXP (note
, 0);
1528 else if (GET_CODE (increment
) == IOR
1529 || GET_CODE (increment
) == ASHIFT
1530 || GET_CODE (increment
) == PLUS
)
1532 /* The rs6000 port loads some constants with IOR.
1533 The alpha port loads some constants with ASHIFT and PLUS. */
1534 rtx second_part
= XEXP (increment
, 1);
1535 enum rtx_code code
= GET_CODE (increment
);
1537 src_insn
= PREV_INSN (src_insn
);
1538 increment
= SET_SRC (PATTERN (src_insn
));
1539 /* Don't need the last insn anymore. */
1540 delete_insn (get_last_insn ());
1542 if (GET_CODE (second_part
) != CONST_INT
1543 || GET_CODE (increment
) != CONST_INT
)
1547 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1548 else if (code
== PLUS
)
1549 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1551 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1554 if (GET_CODE (increment
) != CONST_INT
)
1557 /* The insn loading the constant into a register is no longer needed,
1559 delete_insn (get_last_insn ());
1562 if (increment_total
)
1563 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1565 increment_total
= increment
;
1567 /* Check that the source register is the same as the register we expected
1568 to see as the source. If not, something is seriously wrong. */
1569 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1570 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1572 /* Some machines (e.g. the romp), may emit two add instructions for
1573 certain constants, so lets try looking for another add immediately
1574 before this one if we have only seen one add insn so far. */
1580 src_insn
= PREV_INSN (src_insn
);
1581 pattern
= PATTERN (src_insn
);
1583 delete_insn (get_last_insn ());
1591 return increment_total
;
1594 /* Copy REG_NOTES, except for insn references, because not all insn_map
1595 entries are valid yet. We do need to copy registers now though, because
1596 the reg_map entries can change during copying. */
1599 initial_reg_note_copy (notes
, map
)
1601 struct inline_remap
*map
;
1608 copy
= rtx_alloc (GET_CODE (notes
));
1609 PUT_MODE (copy
, GET_MODE (notes
));
1611 if (GET_CODE (notes
) == EXPR_LIST
)
1612 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
);
1613 else if (GET_CODE (notes
) == INSN_LIST
)
1614 /* Don't substitute for these yet. */
1615 XEXP (copy
, 0) = XEXP (notes
, 0);
1619 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1624 /* Fixup insn references in copied REG_NOTES. */
1627 final_reg_note_copy (notes
, map
)
1629 struct inline_remap
*map
;
1633 for (note
= notes
; note
; note
= XEXP (note
, 1))
1634 if (GET_CODE (note
) == INSN_LIST
)
1635 XEXP (note
, 0) = map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1638 /* Copy each instruction in the loop, substituting from map as appropriate.
1639 This is very similar to a loop in expand_inline_function. */
1642 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1643 unroll_type
, start_label
, loop_end
, insert_before
,
1645 rtx copy_start
, copy_end
;
1646 struct inline_remap
*map
;
1649 enum unroll_types unroll_type
;
1650 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1654 int dest_reg_was_split
, i
;
1658 rtx final_label
= 0;
1659 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1661 /* If this isn't the last iteration, then map any references to the
1662 start_label to final_label. Final label will then be emitted immediately
1663 after the end of this loop body if it was ever used.
1665 If this is the last iteration, then map references to the start_label
1667 if (! last_iteration
)
1669 final_label
= gen_label_rtx ();
1670 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
),
1674 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1678 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1679 Else gen_sequence could return a raw pattern for a jump which we pass
1680 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1681 a variety of losing behaviors later. */
1682 emit_note (0, NOTE_INSN_DELETED
);
1687 insn
= NEXT_INSN (insn
);
1689 map
->orig_asm_operands_vector
= 0;
1691 switch (GET_CODE (insn
))
1694 pattern
= PATTERN (insn
);
1698 /* Check to see if this is a giv that has been combined with
1699 some split address givs. (Combined in the sense that
1700 `combine_givs' in loop.c has put two givs in the same register.)
1701 In this case, we must search all givs based on the same biv to
1702 find the address givs. Then split the address givs.
1703 Do this before splitting the giv, since that may map the
1704 SET_DEST to a new register. */
1706 if ((set
= single_set (insn
))
1707 && GET_CODE (SET_DEST (set
)) == REG
1708 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1710 struct iv_class
*bl
;
1711 struct induction
*v
, *tv
;
1712 int regno
= REGNO (SET_DEST (set
));
1714 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1715 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
1717 /* Although the giv_inc amount is not needed here, we must call
1718 calculate_giv_inc here since it might try to delete the
1719 last insn emitted. If we wait until later to call it,
1720 we might accidentally delete insns generated immediately
1721 below by emit_unrolled_add. */
1723 if (! derived_regs
[regno
])
1724 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1726 /* Now find all address giv's that were combined with this
1728 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1729 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1733 /* If this DEST_ADDR giv was not split, then ignore it. */
1734 if (*tv
->location
!= tv
->dest_reg
)
1737 /* Scale this_giv_inc if the multiplicative factors of
1738 the two givs are different. */
1739 this_giv_inc
= INTVAL (giv_inc
);
1740 if (tv
->mult_val
!= v
->mult_val
)
1741 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1742 * INTVAL (tv
->mult_val
));
1744 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1745 *tv
->location
= tv
->dest_reg
;
1747 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1749 /* Must emit an insn to increment the split address
1750 giv. Add in the const_adjust field in case there
1751 was a constant eliminated from the address. */
1752 rtx value
, dest_reg
;
1754 /* tv->dest_reg will be either a bare register,
1755 or else a register plus a constant. */
1756 if (GET_CODE (tv
->dest_reg
) == REG
)
1757 dest_reg
= tv
->dest_reg
;
1759 dest_reg
= XEXP (tv
->dest_reg
, 0);
1761 /* Check for shared address givs, and avoid
1762 incrementing the shared pseudo reg more than
1764 if (! tv
->same_insn
&& ! tv
->shared
)
1766 /* tv->dest_reg may actually be a (PLUS (REG)
1767 (CONST)) here, so we must call plus_constant
1768 to add the const_adjust amount before calling
1769 emit_unrolled_add below. */
1770 value
= plus_constant (tv
->dest_reg
,
1773 /* The constant could be too large for an add
1774 immediate, so can't directly emit an insn
1776 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1780 /* Reset the giv to be just the register again, in case
1781 it is used after the set we have just emitted.
1782 We must subtract the const_adjust factor added in
1784 tv
->dest_reg
= plus_constant (dest_reg
,
1785 - tv
->const_adjust
);
1786 *tv
->location
= tv
->dest_reg
;
1791 /* If this is a setting of a splittable variable, then determine
1792 how to split the variable, create a new set based on this split,
1793 and set up the reg_map so that later uses of the variable will
1794 use the new split variable. */
1796 dest_reg_was_split
= 0;
1798 if ((set
= single_set (insn
))
1799 && GET_CODE (SET_DEST (set
)) == REG
1800 && splittable_regs
[REGNO (SET_DEST (set
))])
1802 int regno
= REGNO (SET_DEST (set
));
1805 dest_reg_was_split
= 1;
1807 giv_dest_reg
= SET_DEST (set
);
1808 if (derived_regs
[regno
])
1810 /* ??? This relies on SET_SRC (SET) to be of
1811 the form (plus (reg) (const_int)), and thus
1812 forces recombine_givs to restrict the kind
1813 of giv derivations it does before unrolling. */
1814 giv_src_reg
= XEXP (SET_SRC (set
), 0);
1815 giv_inc
= XEXP (SET_SRC (set
), 1);
1819 giv_src_reg
= giv_dest_reg
;
1820 /* Compute the increment value for the giv, if it wasn't
1821 already computed above. */
1823 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1825 src_regno
= REGNO (giv_src_reg
);
1827 if (unroll_type
== UNROLL_COMPLETELY
)
1829 /* Completely unrolling the loop. Set the induction
1830 variable to a known constant value. */
1832 /* The value in splittable_regs may be an invariant
1833 value, so we must use plus_constant here. */
1834 splittable_regs
[regno
]
1835 = plus_constant (splittable_regs
[src_regno
],
1838 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1840 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1841 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1845 /* The splittable_regs value must be a REG or a
1846 CONST_INT, so put the entire value in the giv_src_reg
1848 giv_src_reg
= splittable_regs
[regno
];
1849 giv_inc
= const0_rtx
;
1854 /* Partially unrolling loop. Create a new pseudo
1855 register for the iteration variable, and set it to
1856 be a constant plus the original register. Except
1857 on the last iteration, when the result has to
1858 go back into the original iteration var register. */
1860 /* Handle bivs which must be mapped to a new register
1861 when split. This happens for bivs which need their
1862 final value set before loop entry. The new register
1863 for the biv was stored in the biv's first struct
1864 induction entry by find_splittable_regs. */
1866 if (regno
< max_reg_before_loop
1867 && REG_IV_TYPE (regno
) == BASIC_INDUCT
)
1869 giv_src_reg
= reg_biv_class
[regno
]->biv
->src_reg
;
1870 giv_dest_reg
= giv_src_reg
;
1874 /* If non-reduced/final-value givs were split, then
1875 this would have to remap those givs also. See
1876 find_splittable_regs. */
1879 splittable_regs
[regno
]
1880 = GEN_INT (INTVAL (giv_inc
)
1881 + INTVAL (splittable_regs
[src_regno
]));
1882 giv_inc
= splittable_regs
[regno
];
1884 /* Now split the induction variable by changing the dest
1885 of this insn to a new register, and setting its
1886 reg_map entry to point to this new register.
1888 If this is the last iteration, and this is the last insn
1889 that will update the iv, then reuse the original dest,
1890 to ensure that the iv will have the proper value when
1891 the loop exits or repeats.
1893 Using splittable_regs_updates here like this is safe,
1894 because it can only be greater than one if all
1895 instructions modifying the iv are always executed in
1898 if (! last_iteration
1899 || (splittable_regs_updates
[regno
]-- != 1))
1901 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
1903 map
->reg_map
[regno
] = tem
;
1904 record_base_value (REGNO (tem
),
1905 giv_inc
== const0_rtx
1907 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
1908 giv_src_reg
, giv_inc
),
1912 map
->reg_map
[regno
] = giv_src_reg
;
1915 /* The constant being added could be too large for an add
1916 immediate, so can't directly emit an insn here. */
1917 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
1918 copy
= get_last_insn ();
1919 pattern
= PATTERN (copy
);
1923 pattern
= copy_rtx_and_substitute (pattern
, map
);
1924 copy
= emit_insn (pattern
);
1926 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1929 /* If this insn is setting CC0, it may need to look at
1930 the insn that uses CC0 to see what type of insn it is.
1931 In that case, the call to recog via validate_change will
1932 fail. So don't substitute constants here. Instead,
1933 do it when we emit the following insn.
1935 For example, see the pyr.md file. That machine has signed and
1936 unsigned compares. The compare patterns must check the
1937 following branch insn to see which what kind of compare to
1940 If the previous insn set CC0, substitute constants on it as
1942 if (sets_cc0_p (PATTERN (copy
)) != 0)
1947 try_constants (cc0_insn
, map
);
1949 try_constants (copy
, map
);
1952 try_constants (copy
, map
);
1955 /* Make split induction variable constants `permanent' since we
1956 know there are no backward branches across iteration variable
1957 settings which would invalidate this. */
1958 if (dest_reg_was_split
)
1960 int regno
= REGNO (SET_DEST (pattern
));
1962 if ((size_t) regno
< VARRAY_SIZE (map
->const_equiv_varray
)
1963 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
1965 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
1970 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
);
1971 copy
= emit_jump_insn (pattern
);
1972 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1974 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
1975 && ! last_iteration
)
1977 /* This is a branch to the beginning of the loop; this is the
1978 last insn being copied; and this is not the last iteration.
1979 In this case, we want to change the original fall through
1980 case to be a branch past the end of the loop, and the
1981 original jump label case to fall_through. */
1983 if (invert_exp (pattern
, copy
))
1985 if (! redirect_exp (&pattern
,
1986 get_label_from_map (map
,
1988 (JUMP_LABEL (insn
))),
1995 rtx lab
= gen_label_rtx ();
1996 /* Can't do it by reversing the jump (probably because we
1997 couldn't reverse the conditions), so emit a new
1998 jump_insn after COPY, and redirect the jump around
2000 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2001 jmp
= emit_barrier_after (jmp
);
2002 emit_label_after (lab
, jmp
);
2003 LABEL_NUSES (lab
) = 0;
2004 if (! redirect_exp (&pattern
,
2005 get_label_from_map (map
,
2007 (JUMP_LABEL (insn
))),
2015 try_constants (cc0_insn
, map
);
2018 try_constants (copy
, map
);
2020 /* Set the jump label of COPY correctly to avoid problems with
2021 later passes of unroll_loop, if INSN had jump label set. */
2022 if (JUMP_LABEL (insn
))
2026 /* Can't use the label_map for every insn, since this may be
2027 the backward branch, and hence the label was not mapped. */
2028 if ((set
= single_set (copy
)))
2030 tem
= SET_SRC (set
);
2031 if (GET_CODE (tem
) == LABEL_REF
)
2032 label
= XEXP (tem
, 0);
2033 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2035 if (XEXP (tem
, 1) != pc_rtx
)
2036 label
= XEXP (XEXP (tem
, 1), 0);
2038 label
= XEXP (XEXP (tem
, 2), 0);
2042 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2043 JUMP_LABEL (copy
) = label
;
2046 /* An unrecognizable jump insn, probably the entry jump
2047 for a switch statement. This label must have been mapped,
2048 so just use the label_map to get the new jump label. */
2050 = get_label_from_map (map
,
2051 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2054 /* If this is a non-local jump, then must increase the label
2055 use count so that the label will not be deleted when the
2056 original jump is deleted. */
2057 LABEL_NUSES (JUMP_LABEL (copy
))++;
2059 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2060 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2062 rtx pat
= PATTERN (copy
);
2063 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2064 int len
= XVECLEN (pat
, diff_vec_p
);
2067 for (i
= 0; i
< len
; i
++)
2068 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2071 /* If this used to be a conditional jump insn but whose branch
2072 direction is now known, we must do something special. */
2073 if (condjump_p (insn
) && !simplejump_p (insn
) && map
->last_pc_value
)
2076 /* If the previous insn set cc0 for us, delete it. */
2077 if (sets_cc0_p (PREV_INSN (copy
)))
2078 delete_insn (PREV_INSN (copy
));
2081 /* If this is now a no-op, delete it. */
2082 if (map
->last_pc_value
== pc_rtx
)
2084 /* Don't let delete_insn delete the label referenced here,
2085 because we might possibly need it later for some other
2086 instruction in the loop. */
2087 if (JUMP_LABEL (copy
))
2088 LABEL_NUSES (JUMP_LABEL (copy
))++;
2090 if (JUMP_LABEL (copy
))
2091 LABEL_NUSES (JUMP_LABEL (copy
))--;
2095 /* Otherwise, this is unconditional jump so we must put a
2096 BARRIER after it. We could do some dead code elimination
2097 here, but jump.c will do it just as well. */
2103 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
);
2104 copy
= emit_call_insn (pattern
);
2105 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2107 /* Because the USAGE information potentially contains objects other
2108 than hard registers, we need to copy it. */
2109 CALL_INSN_FUNCTION_USAGE (copy
)
2110 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
), map
);
2114 try_constants (cc0_insn
, map
);
2117 try_constants (copy
, map
);
2119 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2120 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2121 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2125 /* If this is the loop start label, then we don't need to emit a
2126 copy of this label since no one will use it. */
2128 if (insn
!= start_label
)
2130 copy
= emit_label (get_label_from_map (map
,
2131 CODE_LABEL_NUMBER (insn
)));
2137 copy
= emit_barrier ();
2141 /* VTOP and CONT notes are valid only before the loop exit test.
2142 If placed anywhere else, loop may generate bad code. */
2143 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2144 the associated rtl. We do not want to share the structure in
2147 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2148 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2149 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2150 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2151 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2152 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2153 NOTE_LINE_NUMBER (insn
));
2163 map
->insn_map
[INSN_UID (insn
)] = copy
;
2165 while (insn
!= copy_end
);
2167 /* Now finish coping the REG_NOTES. */
2171 insn
= NEXT_INSN (insn
);
2172 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2173 || GET_CODE (insn
) == CALL_INSN
)
2174 && map
->insn_map
[INSN_UID (insn
)])
2175 final_reg_note_copy (REG_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2177 while (insn
!= copy_end
);
2179 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2180 each of these notes here, since there may be some important ones, such as
2181 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2182 iteration, because the original notes won't be deleted.
2184 We can't use insert_before here, because when from preconditioning,
2185 insert_before points before the loop. We can't use copy_end, because
2186 there may be insns already inserted after it (which we don't want to
2187 copy) when not from preconditioning code. */
2189 if (! last_iteration
)
2191 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2193 /* VTOP notes are valid only before the loop exit test.
2194 If placed anywhere else, loop may generate bad code.
2195 There is no need to test for NOTE_INSN_LOOP_CONT notes
2196 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2197 instructions before the last insn in the loop, and if the
2198 end test is that short, there will be a VTOP note between
2199 the CONT note and the test. */
2200 if (GET_CODE (insn
) == NOTE
2201 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2202 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2203 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
)
2204 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2208 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2209 emit_label (final_label
);
2211 tem
= gen_sequence ();
2213 emit_insn_before (tem
, insert_before
);
2216 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2217 emitted. This will correctly handle the case where the increment value
2218 won't fit in the immediate field of a PLUS insns. */
2221 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2222 rtx dest_reg
, src_reg
, increment
;
2226 result
= expand_binop (GET_MODE (dest_reg
), add_optab
, src_reg
, increment
,
2227 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2229 if (dest_reg
!= result
)
2230 emit_move_insn (dest_reg
, result
);
2233 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2234 is a backward branch in that range that branches to somewhere between
2235 LOOP_START and INSN. Returns 0 otherwise. */
2237 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2238 In practice, this is not a problem, because this function is seldom called,
2239 and uses a negligible amount of CPU time on average. */
2242 back_branch_in_range_p (insn
, loop_start
, loop_end
)
2244 rtx loop_start
, loop_end
;
2246 rtx p
, q
, target_insn
;
2247 rtx orig_loop_end
= loop_end
;
2249 /* Stop before we get to the backward branch at the end of the loop. */
2250 loop_end
= prev_nonnote_insn (loop_end
);
2251 if (GET_CODE (loop_end
) == BARRIER
)
2252 loop_end
= PREV_INSN (loop_end
);
2254 /* Check in case insn has been deleted, search forward for first non
2255 deleted insn following it. */
2256 while (INSN_DELETED_P (insn
))
2257 insn
= NEXT_INSN (insn
);
2259 /* Check for the case where insn is the last insn in the loop. Deal
2260 with the case where INSN was a deleted loop test insn, in which case
2261 it will now be the NOTE_LOOP_END. */
2262 if (insn
== loop_end
|| insn
== orig_loop_end
)
2265 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2267 if (GET_CODE (p
) == JUMP_INSN
)
2269 target_insn
= JUMP_LABEL (p
);
2271 /* Search from loop_start to insn, to see if one of them is
2272 the target_insn. We can't use INSN_LUID comparisons here,
2273 since insn may not have an LUID entry. */
2274 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2275 if (q
== target_insn
)
2283 /* Try to generate the simplest rtx for the expression
2284 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2288 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2289 rtx mult1
, mult2
, add1
;
2290 enum machine_mode mode
;
2295 /* The modes must all be the same. This should always be true. For now,
2296 check to make sure. */
2297 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2298 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2299 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2302 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2303 will be a constant. */
2304 if (GET_CODE (mult1
) == CONST_INT
)
2311 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2313 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2315 /* Again, put the constant second. */
2316 if (GET_CODE (add1
) == CONST_INT
)
2323 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2325 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2330 /* Searches the list of induction struct's for the biv BL, to try to calculate
2331 the total increment value for one iteration of the loop as a constant.
2333 Returns the increment value as an rtx, simplified as much as possible,
2334 if it can be calculated. Otherwise, returns 0. */
2337 biv_total_increment (bl
, loop_start
, loop_end
)
2338 struct iv_class
*bl
;
2339 rtx loop_start
, loop_end
;
2341 struct induction
*v
;
2344 /* For increment, must check every instruction that sets it. Each
2345 instruction must be executed only once each time through the loop.
2346 To verify this, we check that the insn is always executed, and that
2347 there are no backward branches after the insn that branch to before it.
2348 Also, the insn must have a mult_val of one (to make sure it really is
2351 result
= const0_rtx
;
2352 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2354 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2355 && ! v
->maybe_multiple
)
2356 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2364 /* Determine the initial value of the iteration variable, and the amount
2365 that it is incremented each loop. Use the tables constructed by
2366 the strength reduction pass to calculate these values.
2368 Initial_value and/or increment are set to zero if their values could not
2372 iteration_info (iteration_var
, initial_value
, increment
, loop_start
, loop_end
)
2373 rtx iteration_var
, *initial_value
, *increment
;
2374 rtx loop_start
, loop_end
;
2376 struct iv_class
*bl
;
2378 struct induction
*v
;
2381 /* Clear the result values, in case no answer can be found. */
2385 /* The iteration variable can be either a giv or a biv. Check to see
2386 which it is, and compute the variable's initial value, and increment
2387 value if possible. */
2389 /* If this is a new register, can't handle it since we don't have any
2390 reg_iv_type entry for it. */
2391 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
)
2393 if (loop_dump_stream
)
2394 fprintf (loop_dump_stream
,
2395 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2399 /* Reject iteration variables larger than the host wide int size, since they
2400 could result in a number of iterations greater than the range of our
2401 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2402 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
2403 > HOST_BITS_PER_WIDE_INT
))
2405 if (loop_dump_stream
)
2406 fprintf (loop_dump_stream
,
2407 "Loop unrolling: Iteration var rejected because mode too large.\n");
2410 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
2412 if (loop_dump_stream
)
2413 fprintf (loop_dump_stream
,
2414 "Loop unrolling: Iteration var not an integer.\n");
2417 else if (REG_IV_TYPE (REGNO (iteration_var
)) == BASIC_INDUCT
)
2419 /* When reg_iv_type / reg_iv_info is resized for biv increments
2420 that are turned into givs, reg_biv_class is not resized.
2421 So check here that we don't make an out-of-bounds access. */
2422 if (REGNO (iteration_var
) >= max_reg_before_loop
)
2425 /* Grab initial value, only useful if it is a constant. */
2426 bl
= reg_biv_class
[REGNO (iteration_var
)];
2427 *initial_value
= bl
->initial_value
;
2429 *increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2431 else if (REG_IV_TYPE (REGNO (iteration_var
)) == GENERAL_INDUCT
)
2433 HOST_WIDE_INT offset
= 0;
2434 struct induction
*v
= REG_IV_INFO (REGNO (iteration_var
));
2436 if (REGNO (v
->src_reg
) >= max_reg_before_loop
)
2439 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
2441 /* Increment value is mult_val times the increment value of the biv. */
2443 *increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2446 struct induction
*biv_inc
;
2449 = fold_rtx_mult_add (v
->mult_val
, *increment
, const0_rtx
, v
->mode
);
2450 /* The caller assumes that one full increment has occured at the
2451 first loop test. But that's not true when the biv is incremented
2452 after the giv is set (which is the usual case), e.g.:
2453 i = 6; do {;} while (i++ < 9) .
2454 Therefore, we bias the initial value by subtracting the amount of
2455 the increment that occurs between the giv set and the giv test. */
2456 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
2458 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
2459 offset
-= INTVAL (biv_inc
->add_val
);
2461 offset
*= INTVAL (v
->mult_val
);
2463 if (loop_dump_stream
)
2464 fprintf (loop_dump_stream
,
2465 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2467 /* Initial value is mult_val times the biv's initial value plus
2468 add_val. Only useful if it is a constant. */
2470 = fold_rtx_mult_add (v
->mult_val
,
2471 plus_constant (bl
->initial_value
, offset
),
2472 v
->add_val
, v
->mode
);
2476 if (loop_dump_stream
)
2477 fprintf (loop_dump_stream
,
2478 "Loop unrolling: Not basic or general induction var.\n");
2484 /* For each biv and giv, determine whether it can be safely split into
2485 a different variable for each unrolled copy of the loop body. If it
2486 is safe to split, then indicate that by saving some useful info
2487 in the splittable_regs array.
2489 If the loop is being completely unrolled, then splittable_regs will hold
2490 the current value of the induction variable while the loop is unrolled.
2491 It must be set to the initial value of the induction variable here.
2492 Otherwise, splittable_regs will hold the difference between the current
2493 value of the induction variable and the value the induction variable had
2494 at the top of the loop. It must be set to the value 0 here.
2496 Returns the total number of instructions that set registers that are
2499 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2500 constant values are unnecessary, since we can easily calculate increment
2501 values in this case even if nothing is constant. The increment value
2502 should not involve a multiply however. */
2504 /* ?? Even if the biv/giv increment values aren't constant, it may still
2505 be beneficial to split the variable if the loop is only unrolled a few
2506 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2509 find_splittable_regs (unroll_type
, loop_start
, loop_end
, end_insert_before
,
2510 unroll_number
, n_iterations
)
2511 enum unroll_types unroll_type
;
2512 rtx loop_start
, loop_end
;
2513 rtx end_insert_before
;
2515 unsigned HOST_WIDE_INT n_iterations
;
2517 struct iv_class
*bl
;
2518 struct induction
*v
;
2520 rtx biv_final_value
;
2524 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
2526 /* Biv_total_increment must return a constant value,
2527 otherwise we can not calculate the split values. */
2529 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2530 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2533 /* The loop must be unrolled completely, or else have a known number
2534 of iterations and only one exit, or else the biv must be dead
2535 outside the loop, or else the final value must be known. Otherwise,
2536 it is unsafe to split the biv since it may not have the proper
2537 value on loop exit. */
2539 /* loop_number_exit_count is non-zero if the loop has an exit other than
2540 a fall through at the end. */
2543 biv_final_value
= 0;
2544 if (unroll_type
!= UNROLL_COMPLETELY
2545 && (loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
2546 || unroll_type
== UNROLL_NAIVE
)
2547 && (uid_luid
[REGNO_LAST_UID (bl
->regno
)] >= INSN_LUID (loop_end
)
2549 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2550 || (uid_luid
[REGNO_FIRST_UID (bl
->regno
)]
2551 < INSN_LUID (bl
->init_insn
))
2552 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2553 && ! (biv_final_value
= final_biv_value (bl
, loop_start
, loop_end
,
2557 /* If any of the insns setting the BIV don't do so with a simple
2558 PLUS, we don't know how to split it. */
2559 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2560 if ((tem
= single_set (v
->insn
)) == 0
2561 || GET_CODE (SET_DEST (tem
)) != REG
2562 || REGNO (SET_DEST (tem
)) != bl
->regno
2563 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2566 /* If final value is non-zero, then must emit an instruction which sets
2567 the value of the biv to the proper value. This is done after
2568 handling all of the givs, since some of them may need to use the
2569 biv's value in their initialization code. */
2571 /* This biv is splittable. If completely unrolling the loop, save
2572 the biv's initial value. Otherwise, save the constant zero. */
2574 if (biv_splittable
== 1)
2576 if (unroll_type
== UNROLL_COMPLETELY
)
2578 /* If the initial value of the biv is itself (i.e. it is too
2579 complicated for strength_reduce to compute), or is a hard
2580 register, or it isn't invariant, then we must create a new
2581 pseudo reg to hold the initial value of the biv. */
2583 if (GET_CODE (bl
->initial_value
) == REG
2584 && (REGNO (bl
->initial_value
) == bl
->regno
2585 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2586 || ! invariant_p (bl
->initial_value
)))
2588 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2590 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2591 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2594 if (loop_dump_stream
)
2595 fprintf (loop_dump_stream
, "Biv %d initial value remapped to %d.\n",
2596 bl
->regno
, REGNO (tem
));
2598 splittable_regs
[bl
->regno
] = tem
;
2601 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2604 splittable_regs
[bl
->regno
] = const0_rtx
;
2606 /* Save the number of instructions that modify the biv, so that
2607 we can treat the last one specially. */
2609 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2610 result
+= bl
->biv_count
;
2612 if (loop_dump_stream
)
2613 fprintf (loop_dump_stream
,
2614 "Biv %d safe to split.\n", bl
->regno
);
2617 /* Check every giv that depends on this biv to see whether it is
2618 splittable also. Even if the biv isn't splittable, givs which
2619 depend on it may be splittable if the biv is live outside the
2620 loop, and the givs aren't. */
2622 result
+= find_splittable_givs (bl
, unroll_type
, loop_start
, loop_end
,
2623 increment
, unroll_number
);
2625 /* If final value is non-zero, then must emit an instruction which sets
2626 the value of the biv to the proper value. This is done after
2627 handling all of the givs, since some of them may need to use the
2628 biv's value in their initialization code. */
2629 if (biv_final_value
)
2631 /* If the loop has multiple exits, emit the insns before the
2632 loop to ensure that it will always be executed no matter
2633 how the loop exits. Otherwise emit the insn after the loop,
2634 since this is slightly more efficient. */
2635 if (! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]])
2636 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2641 /* Create a new register to hold the value of the biv, and then
2642 set the biv to its final value before the loop start. The biv
2643 is set to its final value before loop start to ensure that
2644 this insn will always be executed, no matter how the loop
2646 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2647 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2649 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2651 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2655 if (loop_dump_stream
)
2656 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2657 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2659 /* Set up the mapping from the original biv register to the new
2661 bl
->biv
->src_reg
= tem
;
2668 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2669 for the instruction that is using it. Do not make any changes to that
2673 verify_addresses (v
, giv_inc
, unroll_number
)
2674 struct induction
*v
;
2679 rtx orig_addr
= *v
->location
;
2680 rtx last_addr
= plus_constant (v
->dest_reg
,
2681 INTVAL (giv_inc
) * (unroll_number
- 1));
2683 /* First check to see if either address would fail. Handle the fact
2684 that we have may have a match_dup. */
2685 if (! validate_replace_rtx (*v
->location
, v
->dest_reg
, v
->insn
)
2686 || ! validate_replace_rtx (*v
->location
, last_addr
, v
->insn
))
2689 /* Now put things back the way they were before. This should always
2691 if (! validate_replace_rtx (*v
->location
, orig_addr
, v
->insn
))
2697 /* For every giv based on the biv BL, check to determine whether it is
2698 splittable. This is a subroutine to find_splittable_regs ().
2700 Return the number of instructions that set splittable registers. */
2703 find_splittable_givs (bl
, unroll_type
, loop_start
, loop_end
, increment
,
2705 struct iv_class
*bl
;
2706 enum unroll_types unroll_type
;
2707 rtx loop_start
, loop_end
;
2711 struct induction
*v
, *v2
;
2716 /* Scan the list of givs, and set the same_insn field when there are
2717 multiple identical givs in the same insn. */
2718 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2719 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2720 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2724 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2728 /* Only split the giv if it has already been reduced, or if the loop is
2729 being completely unrolled. */
2730 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2733 /* The giv can be split if the insn that sets the giv is executed once
2734 and only once on every iteration of the loop. */
2735 /* An address giv can always be split. v->insn is just a use not a set,
2736 and hence it does not matter whether it is always executed. All that
2737 matters is that all the biv increments are always executed, and we
2738 won't reach here if they aren't. */
2739 if (v
->giv_type
!= DEST_ADDR
2740 && (! v
->always_computable
2741 || back_branch_in_range_p (v
->insn
, loop_start
, loop_end
)))
2744 /* The giv increment value must be a constant. */
2745 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2747 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2750 /* The loop must be unrolled completely, or else have a known number of
2751 iterations and only one exit, or else the giv must be dead outside
2752 the loop, or else the final value of the giv must be known.
2753 Otherwise, it is not safe to split the giv since it may not have the
2754 proper value on loop exit. */
2756 /* The used outside loop test will fail for DEST_ADDR givs. They are
2757 never used outside the loop anyways, so it is always safe to split a
2761 if (unroll_type
!= UNROLL_COMPLETELY
2762 && (loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
2763 || unroll_type
== UNROLL_NAIVE
)
2764 && v
->giv_type
!= DEST_ADDR
2765 /* The next part is true if the pseudo is used outside the loop.
2766 We assume that this is true for any pseudo created after loop
2767 starts, because we don't have a reg_n_info entry for them. */
2768 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2769 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2770 /* Check for the case where the pseudo is set by a shift/add
2771 sequence, in which case the first insn setting the pseudo
2772 is the first insn of the shift/add sequence. */
2773 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2774 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2775 != INSN_UID (XEXP (tem
, 0)))))
2776 /* Line above always fails if INSN was moved by loop opt. */
2777 || (uid_luid
[REGNO_LAST_UID (REGNO (v
->dest_reg
))]
2778 >= INSN_LUID (loop_end
)))
2779 /* Givs made from biv increments are missed by the above test, so
2780 test explicitly for them. */
2781 && (REGNO (v
->dest_reg
) < first_increment_giv
2782 || REGNO (v
->dest_reg
) > last_increment_giv
)
2783 && ! (final_value
= v
->final_value
))
2787 /* Currently, non-reduced/final-value givs are never split. */
2788 /* Should emit insns after the loop if possible, as the biv final value
2791 /* If the final value is non-zero, and the giv has not been reduced,
2792 then must emit an instruction to set the final value. */
2793 if (final_value
&& !v
->new_reg
)
2795 /* Create a new register to hold the value of the giv, and then set
2796 the giv to its final value before the loop start. The giv is set
2797 to its final value before loop start to ensure that this insn
2798 will always be executed, no matter how we exit. */
2799 tem
= gen_reg_rtx (v
->mode
);
2800 emit_insn_before (gen_move_insn (tem
, v
->dest_reg
), loop_start
);
2801 emit_insn_before (gen_move_insn (v
->dest_reg
, final_value
),
2804 if (loop_dump_stream
)
2805 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2806 REGNO (v
->dest_reg
), REGNO (tem
));
2812 /* This giv is splittable. If completely unrolling the loop, save the
2813 giv's initial value. Otherwise, save the constant zero for it. */
2815 if (unroll_type
== UNROLL_COMPLETELY
)
2817 /* It is not safe to use bl->initial_value here, because it may not
2818 be invariant. It is safe to use the initial value stored in
2819 the splittable_regs array if it is set. In rare cases, it won't
2820 be set, so then we do exactly the same thing as
2821 find_splittable_regs does to get a safe value. */
2822 rtx biv_initial_value
;
2824 if (splittable_regs
[bl
->regno
])
2825 biv_initial_value
= splittable_regs
[bl
->regno
];
2826 else if (GET_CODE (bl
->initial_value
) != REG
2827 || (REGNO (bl
->initial_value
) != bl
->regno
2828 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2829 biv_initial_value
= bl
->initial_value
;
2832 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2834 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2835 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2837 biv_initial_value
= tem
;
2839 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2840 v
->add_val
, v
->mode
);
2847 /* If a giv was combined with another giv, then we can only split
2848 this giv if the giv it was combined with was reduced. This
2849 is because the value of v->new_reg is meaningless in this
2851 if (v
->same
&& ! v
->same
->new_reg
)
2853 if (loop_dump_stream
)
2854 fprintf (loop_dump_stream
,
2855 "giv combined with unreduced giv not split.\n");
2858 /* If the giv is an address destination, it could be something other
2859 than a simple register, these have to be treated differently. */
2860 else if (v
->giv_type
== DEST_REG
)
2862 /* If value is not a constant, register, or register plus
2863 constant, then compute its value into a register before
2864 loop start. This prevents invalid rtx sharing, and should
2865 generate better code. We can use bl->initial_value here
2866 instead of splittable_regs[bl->regno] because this code
2867 is going before the loop start. */
2868 if (unroll_type
== UNROLL_COMPLETELY
2869 && GET_CODE (value
) != CONST_INT
2870 && GET_CODE (value
) != REG
2871 && (GET_CODE (value
) != PLUS
2872 || GET_CODE (XEXP (value
, 0)) != REG
2873 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2875 rtx tem
= gen_reg_rtx (v
->mode
);
2876 record_base_value (REGNO (tem
), v
->add_val
, 0);
2877 emit_iv_add_mult (bl
->initial_value
, v
->mult_val
,
2878 v
->add_val
, tem
, loop_start
);
2882 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2883 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
2887 /* Splitting address givs is useful since it will often allow us
2888 to eliminate some increment insns for the base giv as
2891 /* If the addr giv is combined with a dest_reg giv, then all
2892 references to that dest reg will be remapped, which is NOT
2893 what we want for split addr regs. We always create a new
2894 register for the split addr giv, just to be safe. */
2896 /* If we have multiple identical address givs within a
2897 single instruction, then use a single pseudo reg for
2898 both. This is necessary in case one is a match_dup
2901 v
->const_adjust
= 0;
2905 v
->dest_reg
= v
->same_insn
->dest_reg
;
2906 if (loop_dump_stream
)
2907 fprintf (loop_dump_stream
,
2908 "Sharing address givs in insn %d\n",
2909 INSN_UID (v
->insn
));
2911 /* If multiple address GIVs have been combined with the
2912 same dest_reg GIV, do not create a new register for
2914 else if (unroll_type
!= UNROLL_COMPLETELY
2915 && v
->giv_type
== DEST_ADDR
2916 && v
->same
&& v
->same
->giv_type
== DEST_ADDR
2917 && v
->same
->unrolled
2918 /* combine_givs_p may return true for some cases
2919 where the add and mult values are not equal.
2920 To share a register here, the values must be
2922 && rtx_equal_p (v
->same
->mult_val
, v
->mult_val
)
2923 && rtx_equal_p (v
->same
->add_val
, v
->add_val
)
2924 /* If the memory references have different modes,
2925 then the address may not be valid and we must
2926 not share registers. */
2927 && verify_addresses (v
, giv_inc
, unroll_number
))
2929 v
->dest_reg
= v
->same
->dest_reg
;
2932 else if (unroll_type
!= UNROLL_COMPLETELY
)
2934 /* If not completely unrolling the loop, then create a new
2935 register to hold the split value of the DEST_ADDR giv.
2936 Emit insn to initialize its value before loop start. */
2938 rtx tem
= gen_reg_rtx (v
->mode
);
2939 struct induction
*same
= v
->same
;
2940 rtx new_reg
= v
->new_reg
;
2941 record_base_value (REGNO (tem
), v
->add_val
, 0);
2943 if (same
&& same
->derived_from
)
2945 /* calculate_giv_inc doesn't work for derived givs.
2946 copy_loop_body works around the problem for the
2947 DEST_REG givs themselves, but it can't handle
2948 DEST_ADDR givs that have been combined with
2949 a derived DEST_REG giv.
2950 So Handle V as if the giv from which V->SAME has
2951 been derived has been combined with V.
2952 recombine_givs only derives givs from givs that
2953 are reduced the ordinary, so we need not worry
2954 about same->derived_from being in turn derived. */
2956 same
= same
->derived_from
;
2957 new_reg
= express_from (same
, v
);
2958 new_reg
= replace_rtx (new_reg
, same
->dest_reg
,
2962 /* If the address giv has a constant in its new_reg value,
2963 then this constant can be pulled out and put in value,
2964 instead of being part of the initialization code. */
2966 if (GET_CODE (new_reg
) == PLUS
2967 && GET_CODE (XEXP (new_reg
, 1)) == CONST_INT
)
2970 = plus_constant (tem
, INTVAL (XEXP (new_reg
, 1)));
2972 /* Only succeed if this will give valid addresses.
2973 Try to validate both the first and the last
2974 address resulting from loop unrolling, if
2975 one fails, then can't do const elim here. */
2976 if (verify_addresses (v
, giv_inc
, unroll_number
))
2978 /* Save the negative of the eliminated const, so
2979 that we can calculate the dest_reg's increment
2981 v
->const_adjust
= - INTVAL (XEXP (new_reg
, 1));
2983 new_reg
= XEXP (new_reg
, 0);
2984 if (loop_dump_stream
)
2985 fprintf (loop_dump_stream
,
2986 "Eliminating constant from giv %d\n",
2995 /* If the address hasn't been checked for validity yet, do so
2996 now, and fail completely if either the first or the last
2997 unrolled copy of the address is not a valid address
2998 for the instruction that uses it. */
2999 if (v
->dest_reg
== tem
3000 && ! verify_addresses (v
, giv_inc
, unroll_number
))
3002 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3003 if (v2
->same_insn
== v
)
3006 if (loop_dump_stream
)
3007 fprintf (loop_dump_stream
,
3008 "Invalid address for giv at insn %d\n",
3009 INSN_UID (v
->insn
));
3013 v
->new_reg
= new_reg
;
3016 /* We set this after the address check, to guarantee that
3017 the register will be initialized. */
3020 /* To initialize the new register, just move the value of
3021 new_reg into it. This is not guaranteed to give a valid
3022 instruction on machines with complex addressing modes.
3023 If we can't recognize it, then delete it and emit insns
3024 to calculate the value from scratch. */
3025 emit_insn_before (gen_rtx_SET (VOIDmode
, tem
,
3026 copy_rtx (v
->new_reg
)),
3028 if (recog_memoized (PREV_INSN (loop_start
)) < 0)
3032 /* We can't use bl->initial_value to compute the initial
3033 value, because the loop may have been preconditioned.
3034 We must calculate it from NEW_REG. Try using
3035 force_operand instead of emit_iv_add_mult. */
3036 delete_insn (PREV_INSN (loop_start
));
3039 ret
= force_operand (v
->new_reg
, tem
);
3041 emit_move_insn (tem
, ret
);
3042 sequence
= gen_sequence ();
3044 emit_insn_before (sequence
, loop_start
);
3046 if (loop_dump_stream
)
3047 fprintf (loop_dump_stream
,
3048 "Invalid init insn, rewritten.\n");
3053 v
->dest_reg
= value
;
3055 /* Check the resulting address for validity, and fail
3056 if the resulting address would be invalid. */
3057 if (! verify_addresses (v
, giv_inc
, unroll_number
))
3059 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3060 if (v2
->same_insn
== v
)
3063 if (loop_dump_stream
)
3064 fprintf (loop_dump_stream
,
3065 "Invalid address for giv at insn %d\n",
3066 INSN_UID (v
->insn
));
3069 if (v
->same
&& v
->same
->derived_from
)
3071 /* Handle V as if the giv from which V->SAME has
3072 been derived has been combined with V. */
3074 v
->same
= v
->same
->derived_from
;
3075 v
->new_reg
= express_from (v
->same
, v
);
3076 v
->new_reg
= replace_rtx (v
->new_reg
, v
->same
->dest_reg
,
3082 /* Store the value of dest_reg into the insn. This sharing
3083 will not be a problem as this insn will always be copied
3086 *v
->location
= v
->dest_reg
;
3088 /* If this address giv is combined with a dest reg giv, then
3089 save the base giv's induction pointer so that we will be
3090 able to handle this address giv properly. The base giv
3091 itself does not have to be splittable. */
3093 if (v
->same
&& v
->same
->giv_type
== DEST_REG
)
3094 addr_combined_regs
[REGNO (v
->same
->new_reg
)] = v
->same
;
3096 if (GET_CODE (v
->new_reg
) == REG
)
3098 /* This giv maybe hasn't been combined with any others.
3099 Make sure that it's giv is marked as splittable here. */
3101 splittable_regs
[REGNO (v
->new_reg
)] = value
;
3102 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
3104 /* Make it appear to depend upon itself, so that the
3105 giv will be properly split in the main loop above. */
3109 addr_combined_regs
[REGNO (v
->new_reg
)] = v
;
3113 if (loop_dump_stream
)
3114 fprintf (loop_dump_stream
, "DEST_ADDR giv being split.\n");
3120 /* Currently, unreduced giv's can't be split. This is not too much
3121 of a problem since unreduced giv's are not live across loop
3122 iterations anyways. When unrolling a loop completely though,
3123 it makes sense to reduce&split givs when possible, as this will
3124 result in simpler instructions, and will not require that a reg
3125 be live across loop iterations. */
3127 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
3128 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
3129 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
3135 /* Unreduced givs are only updated once by definition. Reduced givs
3136 are updated as many times as their biv is. Mark it so if this is
3137 a splittable register. Don't need to do anything for address givs
3138 where this may not be a register. */
3140 if (GET_CODE (v
->new_reg
) == REG
)
3144 count
= reg_biv_class
[REGNO (v
->src_reg
)]->biv_count
;
3146 if (count
> 1 && v
->derived_from
)
3147 /* In this case, there is one set where the giv insn was and one
3148 set each after each biv increment. (Most are likely dead.) */
3151 splittable_regs_updates
[REGNO (v
->new_reg
)] = count
;
3156 if (loop_dump_stream
)
3160 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
3162 else if (GET_CODE (v
->dest_reg
) != REG
)
3163 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
3165 regnum
= REGNO (v
->dest_reg
);
3166 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
3167 regnum
, INSN_UID (v
->insn
));
3174 /* Try to prove that the register is dead after the loop exits. Trace every
3175 loop exit looking for an insn that will always be executed, which sets
3176 the register to some value, and appears before the first use of the register
3177 is found. If successful, then return 1, otherwise return 0. */
3179 /* ?? Could be made more intelligent in the handling of jumps, so that
3180 it can search past if statements and other similar structures. */
3183 reg_dead_after_loop (reg
, loop_start
, loop_end
)
3184 rtx reg
, loop_start
, loop_end
;
3189 int label_count
= 0;
3190 int this_loop_num
= uid_loop_num
[INSN_UID (loop_start
)];
3192 /* In addition to checking all exits of this loop, we must also check
3193 all exits of inner nested loops that would exit this loop. We don't
3194 have any way to identify those, so we just give up if there are any
3195 such inner loop exits. */
3197 for (label
= loop_number_exit_labels
[this_loop_num
]; label
;
3198 label
= LABEL_NEXTREF (label
))
3201 if (label_count
!= loop_number_exit_count
[this_loop_num
])
3204 /* HACK: Must also search the loop fall through exit, create a label_ref
3205 here which points to the loop_end, and append the loop_number_exit_labels
3207 label
= gen_rtx_LABEL_REF (VOIDmode
, loop_end
);
3208 LABEL_NEXTREF (label
) = loop_number_exit_labels
[this_loop_num
];
3210 for ( ; label
; label
= LABEL_NEXTREF (label
))
3212 /* Succeed if find an insn which sets the biv or if reach end of
3213 function. Fail if find an insn that uses the biv, or if come to
3214 a conditional jump. */
3216 insn
= NEXT_INSN (XEXP (label
, 0));
3219 code
= GET_CODE (insn
);
3220 if (GET_RTX_CLASS (code
) == 'i')
3224 if (reg_referenced_p (reg
, PATTERN (insn
)))
3227 set
= single_set (insn
);
3228 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
3232 if (code
== JUMP_INSN
)
3234 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3236 else if (! simplejump_p (insn
)
3237 /* Prevent infinite loop following infinite loops. */
3238 || jump_count
++ > 20)
3241 insn
= JUMP_LABEL (insn
);
3244 insn
= NEXT_INSN (insn
);
3248 /* Success, the register is dead on all loop exits. */
3252 /* Try to calculate the final value of the biv, the value it will have at
3253 the end of the loop. If we can do it, return that value. */
3256 final_biv_value (bl
, loop_start
, loop_end
, n_iterations
)
3257 struct iv_class
*bl
;
3258 rtx loop_start
, loop_end
;
3259 unsigned HOST_WIDE_INT n_iterations
;
3263 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3265 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3268 /* The final value for reversed bivs must be calculated differently than
3269 for ordinary bivs. In this case, there is already an insn after the
3270 loop which sets this biv's final value (if necessary), and there are
3271 no other loop exits, so we can return any value. */
3274 if (loop_dump_stream
)
3275 fprintf (loop_dump_stream
,
3276 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3281 /* Try to calculate the final value as initial value + (number of iterations
3282 * increment). For this to work, increment must be invariant, the only
3283 exit from the loop must be the fall through at the bottom (otherwise
3284 it may not have its final value when the loop exits), and the initial
3285 value of the biv must be invariant. */
3287 if (n_iterations
!= 0
3288 && ! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
3289 && invariant_p (bl
->initial_value
))
3291 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
3293 if (increment
&& invariant_p (increment
))
3295 /* Can calculate the loop exit value, emit insns after loop
3296 end to calculate this value into a temporary register in
3297 case it is needed later. */
3299 tem
= gen_reg_rtx (bl
->biv
->mode
);
3300 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3301 /* Make sure loop_end is not the last insn. */
3302 if (NEXT_INSN (loop_end
) == 0)
3303 emit_note_after (NOTE_INSN_DELETED
, loop_end
);
3304 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3305 bl
->initial_value
, tem
, NEXT_INSN (loop_end
));
3307 if (loop_dump_stream
)
3308 fprintf (loop_dump_stream
,
3309 "Final biv value for %d, calculated.\n", bl
->regno
);
3315 /* Check to see if the biv is dead at all loop exits. */
3316 if (reg_dead_after_loop (bl
->biv
->src_reg
, loop_start
, loop_end
))
3318 if (loop_dump_stream
)
3319 fprintf (loop_dump_stream
,
3320 "Final biv value for %d, biv dead after loop exit.\n",
3329 /* Try to calculate the final value of the giv, the value it will have at
3330 the end of the loop. If we can do it, return that value. */
3333 final_giv_value (v
, loop_start
, loop_end
, n_iterations
)
3334 struct induction
*v
;
3335 rtx loop_start
, loop_end
;
3336 unsigned HOST_WIDE_INT n_iterations
;
3338 struct iv_class
*bl
;
3341 rtx insert_before
, seq
;
3343 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
3345 /* The final value for givs which depend on reversed bivs must be calculated
3346 differently than for ordinary givs. In this case, there is already an
3347 insn after the loop which sets this giv's final value (if necessary),
3348 and there are no other loop exits, so we can return any value. */
3351 if (loop_dump_stream
)
3352 fprintf (loop_dump_stream
,
3353 "Final giv value for %d, depends on reversed biv\n",
3354 REGNO (v
->dest_reg
));
3358 /* Try to calculate the final value as a function of the biv it depends
3359 upon. The only exit from the loop must be the fall through at the bottom
3360 (otherwise it may not have its final value when the loop exits). */
3362 /* ??? Can calculate the final giv value by subtracting off the
3363 extra biv increments times the giv's mult_val. The loop must have
3364 only one exit for this to work, but the loop iterations does not need
3367 if (n_iterations
!= 0
3368 && ! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]])
3370 /* ?? It is tempting to use the biv's value here since these insns will
3371 be put after the loop, and hence the biv will have its final value
3372 then. However, this fails if the biv is subsequently eliminated.
3373 Perhaps determine whether biv's are eliminable before trying to
3374 determine whether giv's are replaceable so that we can use the
3375 biv value here if it is not eliminable. */
3377 /* We are emitting code after the end of the loop, so we must make
3378 sure that bl->initial_value is still valid then. It will still
3379 be valid if it is invariant. */
3381 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
3383 if (increment
&& invariant_p (increment
)
3384 && invariant_p (bl
->initial_value
))
3386 /* Can calculate the loop exit value of its biv as
3387 (n_iterations * increment) + initial_value */
3389 /* The loop exit value of the giv is then
3390 (final_biv_value - extra increments) * mult_val + add_val.
3391 The extra increments are any increments to the biv which
3392 occur in the loop after the giv's value is calculated.
3393 We must search from the insn that sets the giv to the end
3394 of the loop to calculate this value. */
3396 insert_before
= NEXT_INSN (loop_end
);
3398 /* Put the final biv value in tem. */
3399 tem
= gen_reg_rtx (bl
->biv
->mode
);
3400 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3401 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3402 bl
->initial_value
, tem
, insert_before
);
3404 /* Subtract off extra increments as we find them. */
3405 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3406 insn
= NEXT_INSN (insn
))
3408 struct induction
*biv
;
3410 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3411 if (biv
->insn
== insn
)
3414 tem
= expand_binop (GET_MODE (tem
), sub_optab
, tem
,
3415 biv
->add_val
, NULL_RTX
, 0,
3417 seq
= gen_sequence ();
3419 emit_insn_before (seq
, insert_before
);
3423 /* Now calculate the giv's final value. */
3424 emit_iv_add_mult (tem
, v
->mult_val
, v
->add_val
, tem
,
3427 if (loop_dump_stream
)
3428 fprintf (loop_dump_stream
,
3429 "Final giv value for %d, calc from biv's value.\n",
3430 REGNO (v
->dest_reg
));
3436 /* Replaceable giv's should never reach here. */
3440 /* Check to see if the biv is dead at all loop exits. */
3441 if (reg_dead_after_loop (v
->dest_reg
, loop_start
, loop_end
))
3443 if (loop_dump_stream
)
3444 fprintf (loop_dump_stream
,
3445 "Final giv value for %d, giv dead after loop exit.\n",
3446 REGNO (v
->dest_reg
));
3455 /* Look back before LOOP_START for then insn that sets REG and return
3456 the equivalent constant if there is a REG_EQUAL note otherwise just
3457 the SET_SRC of REG. */
3460 loop_find_equiv_value (loop_start
, reg
)
3468 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3470 if (GET_CODE (insn
) == CODE_LABEL
)
3473 else if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i'
3474 && reg_set_p (reg
, insn
))
3476 /* We found the last insn before the loop that sets the register.
3477 If it sets the entire register, and has a REG_EQUAL note,
3478 then use the value of the REG_EQUAL note. */
3479 if ((set
= single_set (insn
))
3480 && (SET_DEST (set
) == reg
))
3482 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3484 /* Only use the REG_EQUAL note if it is a constant.
3485 Other things, divide in particular, will cause
3486 problems later if we use them. */
3487 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3488 && CONSTANT_P (XEXP (note
, 0)))
3489 ret
= XEXP (note
, 0);
3491 ret
= SET_SRC (set
);
3499 /* Return a simplified rtx for the expression OP - REG.
3501 REG must appear in OP, and OP must be a register or the sum of a register
3504 Thus, the return value must be const0_rtx or the second term.
3506 The caller is responsible for verifying that REG appears in OP and OP has
3510 subtract_reg_term (op
, reg
)
3515 if (GET_CODE (op
) == PLUS
)
3517 if (XEXP (op
, 0) == reg
)
3518 return XEXP (op
, 1);
3519 else if (XEXP (op
, 1) == reg
)
3520 return XEXP (op
, 0);
3522 /* OP does not contain REG as a term. */
3527 /* Find and return register term common to both expressions OP0 and
3528 OP1 or NULL_RTX if no such term exists. Each expression must be a
3529 REG or a PLUS of a REG. */
3532 find_common_reg_term (op0
, op1
)
3535 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3536 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3543 if (GET_CODE (op0
) == PLUS
)
3544 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3546 op01
= const0_rtx
, op00
= op0
;
3548 if (GET_CODE (op1
) == PLUS
)
3549 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3551 op11
= const0_rtx
, op10
= op1
;
3553 /* Find and return common register term if present. */
3554 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3556 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3560 /* No common register term found. */
3564 /* Calculate the number of loop iterations. Returns the exact number of loop
3565 iterations if it can be calculated, otherwise returns zero. */
3567 unsigned HOST_WIDE_INT
3568 loop_iterations (loop_start
, loop_end
, loop_info
)
3569 rtx loop_start
, loop_end
;
3570 struct loop_info
*loop_info
;
3572 rtx comparison
, comparison_value
;
3573 rtx iteration_var
, initial_value
, increment
, final_value
;
3574 enum rtx_code comparison_code
;
3575 HOST_WIDE_INT abs_inc
;
3576 unsigned HOST_WIDE_INT abs_diff
;
3579 int unsigned_p
, compare_dir
, final_larger
;
3583 loop_info
->n_iterations
= 0;
3584 loop_info
->initial_value
= 0;
3585 loop_info
->initial_equiv_value
= 0;
3586 loop_info
->comparison_value
= 0;
3587 loop_info
->final_value
= 0;
3588 loop_info
->final_equiv_value
= 0;
3589 loop_info
->increment
= 0;
3590 loop_info
->iteration_var
= 0;
3591 loop_info
->unroll_number
= 1;
3593 /* We used to use prev_nonnote_insn here, but that fails because it might
3594 accidentally get the branch for a contained loop if the branch for this
3595 loop was deleted. We can only trust branches immediately before the
3597 last_loop_insn
= PREV_INSN (loop_end
);
3599 /* ??? We should probably try harder to find the jump insn
3600 at the end of the loop. The following code assumes that
3601 the last loop insn is a jump to the top of the loop. */
3602 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3604 if (loop_dump_stream
)
3605 fprintf (loop_dump_stream
,
3606 "Loop iterations: No final conditional branch found.\n");
3610 /* If there is a more than a single jump to the top of the loop
3611 we cannot (easily) determine the iteration count. */
3612 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3614 if (loop_dump_stream
)
3615 fprintf (loop_dump_stream
,
3616 "Loop iterations: Loop has multiple back edges.\n");
3620 /* Find the iteration variable. If the last insn is a conditional
3621 branch, and the insn before tests a register value, make that the
3622 iteration variable. */
3624 comparison
= get_condition_for_loop (last_loop_insn
);
3625 if (comparison
== 0)
3627 if (loop_dump_stream
)
3628 fprintf (loop_dump_stream
,
3629 "Loop iterations: No final comparison found.\n");
3633 /* ??? Get_condition may switch position of induction variable and
3634 invariant register when it canonicalizes the comparison. */
3636 comparison_code
= GET_CODE (comparison
);
3637 iteration_var
= XEXP (comparison
, 0);
3638 comparison_value
= XEXP (comparison
, 1);
3640 if (GET_CODE (iteration_var
) != REG
)
3642 if (loop_dump_stream
)
3643 fprintf (loop_dump_stream
,
3644 "Loop iterations: Comparison not against register.\n");
3648 /* The only new registers that care created before loop iterations are
3649 givs made from biv increments, so this should never occur. */
3651 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
)
3654 iteration_info (iteration_var
, &initial_value
, &increment
,
3655 loop_start
, loop_end
);
3656 if (initial_value
== 0)
3657 /* iteration_info already printed a message. */
3662 switch (comparison_code
)
3677 /* Cannot determine loop iterations with this case. */
3696 /* If the comparison value is an invariant register, then try to find
3697 its value from the insns before the start of the loop. */
3699 final_value
= comparison_value
;
3700 if (GET_CODE (comparison_value
) == REG
&& invariant_p (comparison_value
))
3702 final_value
= loop_find_equiv_value (loop_start
, comparison_value
);
3703 /* If we don't get an invariant final value, we are better
3704 off with the original register. */
3705 if (!invariant_p (final_value
))
3706 final_value
= comparison_value
;
3709 /* Calculate the approximate final value of the induction variable
3710 (on the last successful iteration). The exact final value
3711 depends on the branch operator, and increment sign. It will be
3712 wrong if the iteration variable is not incremented by one each
3713 time through the loop and (comparison_value + off_by_one -
3714 initial_value) % increment != 0.
3715 ??? Note that the final_value may overflow and thus final_larger
3716 will be bogus. A potentially infinite loop will be classified
3717 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3719 final_value
= plus_constant (final_value
, off_by_one
);
3721 /* Save the calculated values describing this loop's bounds, in case
3722 precondition_loop_p will need them later. These values can not be
3723 recalculated inside precondition_loop_p because strength reduction
3724 optimizations may obscure the loop's structure.
3726 These values are only required by precondition_loop_p and insert_bct
3727 whenever the number of iterations cannot be computed at compile time.
3728 Only the difference between final_value and initial_value is
3729 important. Note that final_value is only approximate. */
3730 loop_info
->initial_value
= initial_value
;
3731 loop_info
->comparison_value
= comparison_value
;
3732 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3733 loop_info
->increment
= increment
;
3734 loop_info
->iteration_var
= iteration_var
;
3735 loop_info
->comparison_code
= comparison_code
;
3737 /* Try to determine the iteration count for loops such
3738 as (for i = init; i < init + const; i++). When running the
3739 loop optimization twice, the first pass often converts simple
3740 loops into this form. */
3742 if (REG_P (initial_value
))
3748 reg1
= initial_value
;
3749 if (GET_CODE (final_value
) == PLUS
)
3750 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3752 reg2
= final_value
, const2
= const0_rtx
;
3754 /* Check for initial_value = reg1, final_value = reg2 + const2,
3755 where reg1 != reg2. */
3756 if (REG_P (reg2
) && reg2
!= reg1
)
3760 /* Find what reg1 is equivalent to. Hopefully it will
3761 either be reg2 or reg2 plus a constant. */
3762 temp
= loop_find_equiv_value (loop_start
, reg1
);
3763 if (find_common_reg_term (temp
, reg2
))
3764 initial_value
= temp
;
3767 /* Find what reg2 is equivalent to. Hopefully it will
3768 either be reg1 or reg1 plus a constant. Let's ignore
3769 the latter case for now since it is not so common. */
3770 temp
= loop_find_equiv_value (loop_start
, reg2
);
3771 if (temp
== loop_info
->iteration_var
)
3772 temp
= initial_value
;
3774 final_value
= (const2
== const0_rtx
)
3775 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3778 else if (loop_info
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3782 /* When running the loop optimizer twice, check_dbra_loop
3783 further obfuscates reversible loops of the form:
3784 for (i = init; i < init + const; i++). We often end up with
3785 final_value = 0, initial_value = temp, temp = temp2 - init,
3786 where temp2 = init + const. If the loop has a vtop we
3787 can replace initial_value with const. */
3789 temp
= loop_find_equiv_value (loop_start
, reg1
);
3790 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3792 rtx temp2
= loop_find_equiv_value (loop_start
, XEXP (temp
, 0));
3793 if (GET_CODE (temp2
) == PLUS
3794 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3795 initial_value
= XEXP (temp2
, 1);
3800 /* If have initial_value = reg + const1 and final_value = reg +
3801 const2, then replace initial_value with const1 and final_value
3802 with const2. This should be safe since we are protected by the
3803 initial comparison before entering the loop if we have a vtop.
3804 For example, a + b < a + c is not equivalent to b < c for all a
3805 when using modulo arithmetic.
3807 ??? Without a vtop we could still perform the optimization if we check
3808 the initial and final values carefully. */
3810 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3812 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3813 final_value
= subtract_reg_term (final_value
, reg_term
);
3816 loop_info
->initial_equiv_value
= initial_value
;
3817 loop_info
->final_equiv_value
= final_value
;
3819 /* For EQ comparison loops, we don't have a valid final value.
3820 Check this now so that we won't leave an invalid value if we
3821 return early for any other reason. */
3822 if (comparison_code
== EQ
)
3823 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3827 if (loop_dump_stream
)
3828 fprintf (loop_dump_stream
,
3829 "Loop iterations: Increment value can't be calculated.\n");
3833 if (GET_CODE (increment
) != CONST_INT
)
3835 /* If we have a REG, check to see if REG holds a constant value. */
3836 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3837 clear if it is worthwhile to try to handle such RTL. */
3838 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3839 increment
= loop_find_equiv_value (loop_start
, increment
);
3841 if (GET_CODE (increment
) != CONST_INT
)
3843 if (loop_dump_stream
)
3845 fprintf (loop_dump_stream
,
3846 "Loop iterations: Increment value not constant ");
3847 print_rtl (loop_dump_stream
, increment
);
3848 fprintf (loop_dump_stream
, ".\n");
3852 loop_info
->increment
= increment
;
3855 if (GET_CODE (initial_value
) != CONST_INT
)
3857 if (loop_dump_stream
)
3859 fprintf (loop_dump_stream
,
3860 "Loop iterations: Initial value not constant ");
3861 print_rtl (loop_dump_stream
, initial_value
);
3862 fprintf (loop_dump_stream
, ".\n");
3866 else if (comparison_code
== EQ
)
3868 if (loop_dump_stream
)
3869 fprintf (loop_dump_stream
,
3870 "Loop iterations: EQ comparison loop.\n");
3873 else if (GET_CODE (final_value
) != CONST_INT
)
3875 if (loop_dump_stream
)
3877 fprintf (loop_dump_stream
,
3878 "Loop iterations: Final value not constant ");
3879 print_rtl (loop_dump_stream
, final_value
);
3880 fprintf (loop_dump_stream
, ".\n");
3885 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3888 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3889 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3890 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3891 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3893 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3894 - (INTVAL (final_value
) < INTVAL (initial_value
));
3896 if (INTVAL (increment
) > 0)
3898 else if (INTVAL (increment
) == 0)
3903 /* There are 27 different cases: compare_dir = -1, 0, 1;
3904 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3905 There are 4 normal cases, 4 reverse cases (where the iteration variable
3906 will overflow before the loop exits), 4 infinite loop cases, and 15
3907 immediate exit (0 or 1 iteration depending on loop type) cases.
3908 Only try to optimize the normal cases. */
3910 /* (compare_dir/final_larger/increment_dir)
3911 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3912 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3913 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3914 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3916 /* ?? If the meaning of reverse loops (where the iteration variable
3917 will overflow before the loop exits) is undefined, then could
3918 eliminate all of these special checks, and just always assume
3919 the loops are normal/immediate/infinite. Note that this means
3920 the sign of increment_dir does not have to be known. Also,
3921 since it does not really hurt if immediate exit loops or infinite loops
3922 are optimized, then that case could be ignored also, and hence all
3923 loops can be optimized.
3925 According to ANSI Spec, the reverse loop case result is undefined,
3926 because the action on overflow is undefined.
3928 See also the special test for NE loops below. */
3930 if (final_larger
== increment_dir
&& final_larger
!= 0
3931 && (final_larger
== compare_dir
|| compare_dir
== 0))
3936 if (loop_dump_stream
)
3937 fprintf (loop_dump_stream
,
3938 "Loop iterations: Not normal loop.\n");
3942 /* Calculate the number of iterations, final_value is only an approximation,
3943 so correct for that. Note that abs_diff and n_iterations are
3944 unsigned, because they can be as large as 2^n - 1. */
3946 abs_inc
= INTVAL (increment
);
3948 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
3949 else if (abs_inc
< 0)
3951 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
3957 /* For NE tests, make sure that the iteration variable won't miss
3958 the final value. If abs_diff mod abs_incr is not zero, then the
3959 iteration variable will overflow before the loop exits, and we
3960 can not calculate the number of iterations. */
3961 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
3964 /* Note that the number of iterations could be calculated using
3965 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3966 handle potential overflow of the summation. */
3967 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
3968 return loop_info
->n_iterations
;
3972 /* Replace uses of split bivs with their split pseudo register. This is
3973 for original instructions which remain after loop unrolling without
3977 remap_split_bivs (x
)
3980 register enum rtx_code code
;
3982 register const char *fmt
;
3987 code
= GET_CODE (x
);
4002 /* If non-reduced/final-value givs were split, then this would also
4003 have to remap those givs also. */
4005 if (REGNO (x
) < max_reg_before_loop
4006 && REG_IV_TYPE (REGNO (x
)) == BASIC_INDUCT
)
4007 return reg_biv_class
[REGNO (x
)]->biv
->src_reg
;
4014 fmt
= GET_RTX_FORMAT (code
);
4015 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4018 XEXP (x
, i
) = remap_split_bivs (XEXP (x
, i
));
4022 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4023 XVECEXP (x
, i
, j
) = remap_split_bivs (XVECEXP (x
, i
, j
));
4029 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4030 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4031 return 0. COPY_START is where we can start looking for the insns
4032 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4035 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4036 must dominate LAST_UID.
4038 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4039 may not dominate LAST_UID.
4041 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4042 must dominate LAST_UID. */
4045 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
4052 int passed_jump
= 0;
4053 rtx p
= NEXT_INSN (copy_start
);
4055 while (INSN_UID (p
) != first_uid
)
4057 if (GET_CODE (p
) == JUMP_INSN
)
4059 /* Could not find FIRST_UID. */
4065 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4066 if (GET_RTX_CLASS (GET_CODE (p
)) != 'i'
4067 || ! dead_or_set_regno_p (p
, regno
))
4070 /* FIRST_UID is always executed. */
4071 if (passed_jump
== 0)
4074 while (INSN_UID (p
) != last_uid
)
4076 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4077 can not be sure that FIRST_UID dominates LAST_UID. */
4078 if (GET_CODE (p
) == CODE_LABEL
)
4080 /* Could not find LAST_UID, but we reached the end of the loop, so
4082 else if (p
== copy_end
)
4087 /* FIRST_UID is always executed if LAST_UID is executed. */