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
;
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 if (unroll_type
== UNROLL_COMPLETELY
)
1121 loop_info
->unroll_number
= -1;
1123 loop_info
->unroll_number
= unroll_number
;
1126 /* For each biv and giv, determine whether it can be safely split into
1127 a different variable for each unrolled copy of the loop body.
1128 We precalculate and save this info here, since computing it is
1131 Do this before deleting any instructions from the loop, so that
1132 back_branch_in_range_p will work correctly. */
1134 if (splitting_not_safe
)
1137 temp
= find_splittable_regs (unroll_type
, loop_start
, loop_end
,
1138 end_insert_before
, unroll_number
,
1139 loop_info
->n_iterations
);
1141 /* find_splittable_regs may have created some new registers, so must
1142 reallocate the reg_map with the new larger size, and must realloc
1143 the constant maps also. */
1145 maxregnum
= max_reg_num ();
1146 map
->reg_map
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
1148 init_reg_map (map
, maxregnum
);
1150 if (map
->const_equiv_varray
== 0)
1151 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1152 maxregnum
+ temp
* unroll_number
* 2,
1154 global_const_equiv_varray
= map
->const_equiv_varray
;
1156 /* Search the list of bivs and givs to find ones which need to be remapped
1157 when split, and set their reg_map entry appropriately. */
1159 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
1161 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1162 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1164 /* Currently, non-reduced/final-value givs are never split. */
1165 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1166 if (REGNO (v
->src_reg
) != bl
->regno
)
1167 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1171 /* Use our current register alignment and pointer flags. */
1172 map
->regno_pointer_flag
= current_function
->emit
->regno_pointer_flag
;
1173 map
->regno_pointer_align
= current_function
->emit
->regno_pointer_align
;
1175 /* If the loop is being partially unrolled, and the iteration variables
1176 are being split, and are being renamed for the split, then must fix up
1177 the compare/jump instruction at the end of the loop to refer to the new
1178 registers. This compare isn't copied, so the registers used in it
1179 will never be replaced if it isn't done here. */
1181 if (unroll_type
== UNROLL_MODULO
)
1183 insn
= NEXT_INSN (copy_end
);
1184 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1185 PATTERN (insn
) = remap_split_bivs (PATTERN (insn
));
1188 /* For unroll_number times, make a copy of each instruction
1189 between copy_start and copy_end, and insert these new instructions
1190 before the end of the loop. */
1192 for (i
= 0; i
< unroll_number
; i
++)
1194 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1195 bzero ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1196 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1199 for (j
= 0; j
< max_labelno
; j
++)
1201 set_label_in_map (map
, j
, gen_label_rtx ());
1203 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_local_regnum
; j
++)
1206 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1207 record_base_value (REGNO (map
->reg_map
[j
]),
1208 regno_reg_rtx
[j
], 0);
1211 /* If loop starts with a branch to the test, then fix it so that
1212 it points to the test of the first unrolled copy of the loop. */
1213 if (i
== 0 && loop_start
!= copy_start
)
1215 insn
= PREV_INSN (copy_start
);
1216 pattern
= PATTERN (insn
);
1218 tem
= get_label_from_map (map
,
1220 (XEXP (SET_SRC (pattern
), 0)));
1221 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1223 /* Set the jump label so that it can be used by later loop unrolling
1225 JUMP_LABEL (insn
) = tem
;
1226 LABEL_NUSES (tem
)++;
1229 copy_loop_body (copy_start
, copy_end
, map
, exit_label
,
1230 i
== unroll_number
- 1, unroll_type
, start_label
,
1231 loop_end
, insert_before
, insert_before
);
1234 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1235 insn to be deleted. This prevents any runaway delete_insn call from
1236 more insns that it should, as it always stops at a CODE_LABEL. */
1238 /* Delete the compare and branch at the end of the loop if completely
1239 unrolling the loop. Deleting the backward branch at the end also
1240 deletes the code label at the start of the loop. This is done at
1241 the very end to avoid problems with back_branch_in_range_p. */
1243 if (unroll_type
== UNROLL_COMPLETELY
)
1244 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1246 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1248 /* Delete all of the original loop instructions. Don't delete the
1249 LOOP_BEG note, or the first code label in the loop. */
1251 insn
= NEXT_INSN (copy_start
);
1252 while (insn
!= safety_label
)
1254 /* ??? Don't delete named code labels. They will be deleted when the
1255 jump that references them is deleted. Otherwise, we end up deleting
1256 them twice, which causes them to completely disappear instead of turn
1257 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1258 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1259 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1260 associated LABEL_DECL to point to one of the new label instances. */
1261 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1262 if (insn
!= start_label
1263 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1264 && ! (GET_CODE (insn
) == NOTE
1265 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1266 insn
= delete_insn (insn
);
1268 insn
= NEXT_INSN (insn
);
1271 /* Can now delete the 'safety' label emitted to protect us from runaway
1272 delete_insn calls. */
1273 if (INSN_DELETED_P (safety_label
))
1275 delete_insn (safety_label
);
1277 /* If exit_label exists, emit it after the loop. Doing the emit here
1278 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1279 This is needed so that mostly_true_jump in reorg.c will treat jumps
1280 to this loop end label correctly, i.e. predict that they are usually
1283 emit_label_after (exit_label
, loop_end
);
1286 if (map
&& map
->const_equiv_varray
)
1287 VARRAY_FREE (map
->const_equiv_varray
);
1290 /* Return true if the loop can be safely, and profitably, preconditioned
1291 so that the unrolled copies of the loop body don't need exit tests.
1293 This only works if final_value, initial_value and increment can be
1294 determined, and if increment is a constant power of 2.
1295 If increment is not a power of 2, then the preconditioning modulo
1296 operation would require a real modulo instead of a boolean AND, and this
1297 is not considered `profitable'. */
1299 /* ??? If the loop is known to be executed very many times, or the machine
1300 has a very cheap divide instruction, then preconditioning is a win even
1301 when the increment is not a power of 2. Use RTX_COST to compute
1302 whether divide is cheap.
1303 ??? A divide by constant doesn't actually need a divide, look at
1304 expand_divmod. The reduced cost of this optimized modulo is not
1305 reflected in RTX_COST. */
1308 precondition_loop_p (loop_start
, loop_info
,
1309 initial_value
, final_value
, increment
, mode
)
1311 struct loop_info
*loop_info
;
1312 rtx
*initial_value
, *final_value
, *increment
;
1313 enum machine_mode
*mode
;
1316 if (loop_info
->n_iterations
> 0)
1318 *initial_value
= const0_rtx
;
1319 *increment
= const1_rtx
;
1320 *final_value
= GEN_INT (loop_info
->n_iterations
);
1323 if (loop_dump_stream
)
1325 fputs ("Preconditioning: Success, number of iterations known, ",
1327 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
1328 loop_info
->n_iterations
);
1329 fputs (".\n", loop_dump_stream
);
1334 if (loop_info
->initial_value
== 0)
1336 if (loop_dump_stream
)
1337 fprintf (loop_dump_stream
,
1338 "Preconditioning: Could not find initial value.\n");
1341 else if (loop_info
->increment
== 0)
1343 if (loop_dump_stream
)
1344 fprintf (loop_dump_stream
,
1345 "Preconditioning: Could not find increment value.\n");
1348 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1350 if (loop_dump_stream
)
1351 fprintf (loop_dump_stream
,
1352 "Preconditioning: Increment not a constant.\n");
1355 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1356 && (exact_log2 (- INTVAL (loop_info
->increment
)) < 0))
1358 if (loop_dump_stream
)
1359 fprintf (loop_dump_stream
,
1360 "Preconditioning: Increment not a constant power of 2.\n");
1364 /* Unsigned_compare and compare_dir can be ignored here, since they do
1365 not matter for preconditioning. */
1367 if (loop_info
->final_value
== 0)
1369 if (loop_dump_stream
)
1370 fprintf (loop_dump_stream
,
1371 "Preconditioning: EQ comparison loop.\n");
1375 /* Must ensure that final_value is invariant, so call invariant_p to
1376 check. Before doing so, must check regno against max_reg_before_loop
1377 to make sure that the register is in the range covered by invariant_p.
1378 If it isn't, then it is most likely a biv/giv which by definition are
1380 if ((GET_CODE (loop_info
->final_value
) == REG
1381 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1382 || (GET_CODE (loop_info
->final_value
) == PLUS
1383 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1384 || ! invariant_p (loop_info
->final_value
))
1386 if (loop_dump_stream
)
1387 fprintf (loop_dump_stream
,
1388 "Preconditioning: Final value not invariant.\n");
1392 /* Fail for floating point values, since the caller of this function
1393 does not have code to deal with them. */
1394 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1395 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1397 if (loop_dump_stream
)
1398 fprintf (loop_dump_stream
,
1399 "Preconditioning: Floating point final or initial value.\n");
1403 /* Fail if loop_info->iteration_var is not live before loop_start,
1404 since we need to test its value in the preconditioning code. */
1406 if (uid_luid
[REGNO_FIRST_UID (REGNO (loop_info
->iteration_var
))]
1407 > INSN_LUID (loop_start
))
1409 if (loop_dump_stream
)
1410 fprintf (loop_dump_stream
,
1411 "Preconditioning: Iteration var not live before loop start.\n");
1415 /* Note that iteration_info biases the initial value for GIV iterators
1416 such as "while (i-- > 0)" so that we can calculate the number of
1417 iterations just like for BIV iterators.
1419 Also note that the absolute values of initial_value and
1420 final_value are unimportant as only their difference is used for
1421 calculating the number of loop iterations. */
1422 *initial_value
= loop_info
->initial_value
;
1423 *increment
= loop_info
->increment
;
1424 *final_value
= loop_info
->final_value
;
1426 /* Decide what mode to do these calculations in. Choose the larger
1427 of final_value's mode and initial_value's mode, or a full-word if
1428 both are constants. */
1429 *mode
= GET_MODE (*final_value
);
1430 if (*mode
== VOIDmode
)
1432 *mode
= GET_MODE (*initial_value
);
1433 if (*mode
== VOIDmode
)
1436 else if (*mode
!= GET_MODE (*initial_value
)
1437 && (GET_MODE_SIZE (*mode
)
1438 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1439 *mode
= GET_MODE (*initial_value
);
1442 if (loop_dump_stream
)
1443 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1448 /* All pseudo-registers must be mapped to themselves. Two hard registers
1449 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1450 REGNUM, to avoid function-inlining specific conversions of these
1451 registers. All other hard regs can not be mapped because they may be
1456 init_reg_map (map
, maxregnum
)
1457 struct inline_remap
*map
;
1462 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1463 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1464 /* Just clear the rest of the entries. */
1465 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1466 map
->reg_map
[i
] = 0;
1468 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1469 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1470 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1471 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1474 /* Strength-reduction will often emit code for optimized biv/givs which
1475 calculates their value in a temporary register, and then copies the result
1476 to the iv. This procedure reconstructs the pattern computing the iv;
1477 verifying that all operands are of the proper form.
1479 PATTERN must be the result of single_set.
1480 The return value is the amount that the giv is incremented by. */
1483 calculate_giv_inc (pattern
, src_insn
, regno
)
1484 rtx pattern
, src_insn
;
1488 rtx increment_total
= 0;
1492 /* Verify that we have an increment insn here. First check for a plus
1493 as the set source. */
1494 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1496 /* SR sometimes computes the new giv value in a temp, then copies it
1498 src_insn
= PREV_INSN (src_insn
);
1499 pattern
= PATTERN (src_insn
);
1500 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1503 /* The last insn emitted is not needed, so delete it to avoid confusing
1504 the second cse pass. This insn sets the giv unnecessarily. */
1505 delete_insn (get_last_insn ());
1508 /* Verify that we have a constant as the second operand of the plus. */
1509 increment
= XEXP (SET_SRC (pattern
), 1);
1510 if (GET_CODE (increment
) != CONST_INT
)
1512 /* SR sometimes puts the constant in a register, especially if it is
1513 too big to be an add immed operand. */
1514 src_insn
= PREV_INSN (src_insn
);
1515 increment
= SET_SRC (PATTERN (src_insn
));
1517 /* SR may have used LO_SUM to compute the constant if it is too large
1518 for a load immed operand. In this case, the constant is in operand
1519 one of the LO_SUM rtx. */
1520 if (GET_CODE (increment
) == LO_SUM
)
1521 increment
= XEXP (increment
, 1);
1523 /* Some ports store large constants in memory and add a REG_EQUAL
1524 note to the store insn. */
1525 else if (GET_CODE (increment
) == MEM
)
1527 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1529 increment
= XEXP (note
, 0);
1532 else if (GET_CODE (increment
) == IOR
1533 || GET_CODE (increment
) == ASHIFT
1534 || GET_CODE (increment
) == PLUS
)
1536 /* The rs6000 port loads some constants with IOR.
1537 The alpha port loads some constants with ASHIFT and PLUS. */
1538 rtx second_part
= XEXP (increment
, 1);
1539 enum rtx_code code
= GET_CODE (increment
);
1541 src_insn
= PREV_INSN (src_insn
);
1542 increment
= SET_SRC (PATTERN (src_insn
));
1543 /* Don't need the last insn anymore. */
1544 delete_insn (get_last_insn ());
1546 if (GET_CODE (second_part
) != CONST_INT
1547 || GET_CODE (increment
) != CONST_INT
)
1551 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1552 else if (code
== PLUS
)
1553 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1555 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1558 if (GET_CODE (increment
) != CONST_INT
)
1561 /* The insn loading the constant into a register is no longer needed,
1563 delete_insn (get_last_insn ());
1566 if (increment_total
)
1567 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1569 increment_total
= increment
;
1571 /* Check that the source register is the same as the register we expected
1572 to see as the source. If not, something is seriously wrong. */
1573 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1574 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1576 /* Some machines (e.g. the romp), may emit two add instructions for
1577 certain constants, so lets try looking for another add immediately
1578 before this one if we have only seen one add insn so far. */
1584 src_insn
= PREV_INSN (src_insn
);
1585 pattern
= PATTERN (src_insn
);
1587 delete_insn (get_last_insn ());
1595 return increment_total
;
1598 /* Copy REG_NOTES, except for insn references, because not all insn_map
1599 entries are valid yet. We do need to copy registers now though, because
1600 the reg_map entries can change during copying. */
1603 initial_reg_note_copy (notes
, map
)
1605 struct inline_remap
*map
;
1612 copy
= rtx_alloc (GET_CODE (notes
));
1613 PUT_MODE (copy
, GET_MODE (notes
));
1615 if (GET_CODE (notes
) == EXPR_LIST
)
1616 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
);
1617 else if (GET_CODE (notes
) == INSN_LIST
)
1618 /* Don't substitute for these yet. */
1619 XEXP (copy
, 0) = XEXP (notes
, 0);
1623 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1628 /* Fixup insn references in copied REG_NOTES. */
1631 final_reg_note_copy (notes
, map
)
1633 struct inline_remap
*map
;
1637 for (note
= notes
; note
; note
= XEXP (note
, 1))
1638 if (GET_CODE (note
) == INSN_LIST
)
1639 XEXP (note
, 0) = map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1642 /* Copy each instruction in the loop, substituting from map as appropriate.
1643 This is very similar to a loop in expand_inline_function. */
1646 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1647 unroll_type
, start_label
, loop_end
, insert_before
,
1649 rtx copy_start
, copy_end
;
1650 struct inline_remap
*map
;
1653 enum unroll_types unroll_type
;
1654 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1658 int dest_reg_was_split
, i
;
1662 rtx final_label
= 0;
1663 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1665 /* If this isn't the last iteration, then map any references to the
1666 start_label to final_label. Final label will then be emitted immediately
1667 after the end of this loop body if it was ever used.
1669 If this is the last iteration, then map references to the start_label
1671 if (! last_iteration
)
1673 final_label
= gen_label_rtx ();
1674 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
),
1678 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1682 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1683 Else gen_sequence could return a raw pattern for a jump which we pass
1684 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1685 a variety of losing behaviors later. */
1686 emit_note (0, NOTE_INSN_DELETED
);
1691 insn
= NEXT_INSN (insn
);
1693 map
->orig_asm_operands_vector
= 0;
1695 switch (GET_CODE (insn
))
1698 pattern
= PATTERN (insn
);
1702 /* Check to see if this is a giv that has been combined with
1703 some split address givs. (Combined in the sense that
1704 `combine_givs' in loop.c has put two givs in the same register.)
1705 In this case, we must search all givs based on the same biv to
1706 find the address givs. Then split the address givs.
1707 Do this before splitting the giv, since that may map the
1708 SET_DEST to a new register. */
1710 if ((set
= single_set (insn
))
1711 && GET_CODE (SET_DEST (set
)) == REG
1712 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1714 struct iv_class
*bl
;
1715 struct induction
*v
, *tv
;
1716 int regno
= REGNO (SET_DEST (set
));
1718 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1719 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
1721 /* Although the giv_inc amount is not needed here, we must call
1722 calculate_giv_inc here since it might try to delete the
1723 last insn emitted. If we wait until later to call it,
1724 we might accidentally delete insns generated immediately
1725 below by emit_unrolled_add. */
1727 if (! derived_regs
[regno
])
1728 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1730 /* Now find all address giv's that were combined with this
1732 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1733 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1737 /* If this DEST_ADDR giv was not split, then ignore it. */
1738 if (*tv
->location
!= tv
->dest_reg
)
1741 /* Scale this_giv_inc if the multiplicative factors of
1742 the two givs are different. */
1743 this_giv_inc
= INTVAL (giv_inc
);
1744 if (tv
->mult_val
!= v
->mult_val
)
1745 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1746 * INTVAL (tv
->mult_val
));
1748 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1749 *tv
->location
= tv
->dest_reg
;
1751 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1753 /* Must emit an insn to increment the split address
1754 giv. Add in the const_adjust field in case there
1755 was a constant eliminated from the address. */
1756 rtx value
, dest_reg
;
1758 /* tv->dest_reg will be either a bare register,
1759 or else a register plus a constant. */
1760 if (GET_CODE (tv
->dest_reg
) == REG
)
1761 dest_reg
= tv
->dest_reg
;
1763 dest_reg
= XEXP (tv
->dest_reg
, 0);
1765 /* Check for shared address givs, and avoid
1766 incrementing the shared pseudo reg more than
1768 if (! tv
->same_insn
&& ! tv
->shared
)
1770 /* tv->dest_reg may actually be a (PLUS (REG)
1771 (CONST)) here, so we must call plus_constant
1772 to add the const_adjust amount before calling
1773 emit_unrolled_add below. */
1774 value
= plus_constant (tv
->dest_reg
,
1777 /* The constant could be too large for an add
1778 immediate, so can't directly emit an insn
1780 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1784 /* Reset the giv to be just the register again, in case
1785 it is used after the set we have just emitted.
1786 We must subtract the const_adjust factor added in
1788 tv
->dest_reg
= plus_constant (dest_reg
,
1789 - tv
->const_adjust
);
1790 *tv
->location
= tv
->dest_reg
;
1795 /* If this is a setting of a splittable variable, then determine
1796 how to split the variable, create a new set based on this split,
1797 and set up the reg_map so that later uses of the variable will
1798 use the new split variable. */
1800 dest_reg_was_split
= 0;
1802 if ((set
= single_set (insn
))
1803 && GET_CODE (SET_DEST (set
)) == REG
1804 && splittable_regs
[REGNO (SET_DEST (set
))])
1806 int regno
= REGNO (SET_DEST (set
));
1809 dest_reg_was_split
= 1;
1811 giv_dest_reg
= SET_DEST (set
);
1812 if (derived_regs
[regno
])
1814 /* ??? This relies on SET_SRC (SET) to be of
1815 the form (plus (reg) (const_int)), and thus
1816 forces recombine_givs to restrict the kind
1817 of giv derivations it does before unrolling. */
1818 giv_src_reg
= XEXP (SET_SRC (set
), 0);
1819 giv_inc
= XEXP (SET_SRC (set
), 1);
1823 giv_src_reg
= giv_dest_reg
;
1824 /* Compute the increment value for the giv, if it wasn't
1825 already computed above. */
1827 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1829 src_regno
= REGNO (giv_src_reg
);
1831 if (unroll_type
== UNROLL_COMPLETELY
)
1833 /* Completely unrolling the loop. Set the induction
1834 variable to a known constant value. */
1836 /* The value in splittable_regs may be an invariant
1837 value, so we must use plus_constant here. */
1838 splittable_regs
[regno
]
1839 = plus_constant (splittable_regs
[src_regno
],
1842 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1844 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1845 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1849 /* The splittable_regs value must be a REG or a
1850 CONST_INT, so put the entire value in the giv_src_reg
1852 giv_src_reg
= splittable_regs
[regno
];
1853 giv_inc
= const0_rtx
;
1858 /* Partially unrolling loop. Create a new pseudo
1859 register for the iteration variable, and set it to
1860 be a constant plus the original register. Except
1861 on the last iteration, when the result has to
1862 go back into the original iteration var register. */
1864 /* Handle bivs which must be mapped to a new register
1865 when split. This happens for bivs which need their
1866 final value set before loop entry. The new register
1867 for the biv was stored in the biv's first struct
1868 induction entry by find_splittable_regs. */
1870 if (regno
< max_reg_before_loop
1871 && REG_IV_TYPE (regno
) == BASIC_INDUCT
)
1873 giv_src_reg
= reg_biv_class
[regno
]->biv
->src_reg
;
1874 giv_dest_reg
= giv_src_reg
;
1878 /* If non-reduced/final-value givs were split, then
1879 this would have to remap those givs also. See
1880 find_splittable_regs. */
1883 splittable_regs
[regno
]
1884 = GEN_INT (INTVAL (giv_inc
)
1885 + INTVAL (splittable_regs
[src_regno
]));
1886 giv_inc
= splittable_regs
[regno
];
1888 /* Now split the induction variable by changing the dest
1889 of this insn to a new register, and setting its
1890 reg_map entry to point to this new register.
1892 If this is the last iteration, and this is the last insn
1893 that will update the iv, then reuse the original dest,
1894 to ensure that the iv will have the proper value when
1895 the loop exits or repeats.
1897 Using splittable_regs_updates here like this is safe,
1898 because it can only be greater than one if all
1899 instructions modifying the iv are always executed in
1902 if (! last_iteration
1903 || (splittable_regs_updates
[regno
]-- != 1))
1905 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
1907 map
->reg_map
[regno
] = tem
;
1908 record_base_value (REGNO (tem
),
1909 giv_inc
== const0_rtx
1911 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
1912 giv_src_reg
, giv_inc
),
1916 map
->reg_map
[regno
] = giv_src_reg
;
1919 /* The constant being added could be too large for an add
1920 immediate, so can't directly emit an insn here. */
1921 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
1922 copy
= get_last_insn ();
1923 pattern
= PATTERN (copy
);
1927 pattern
= copy_rtx_and_substitute (pattern
, map
);
1928 copy
= emit_insn (pattern
);
1930 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1933 /* If this insn is setting CC0, it may need to look at
1934 the insn that uses CC0 to see what type of insn it is.
1935 In that case, the call to recog via validate_change will
1936 fail. So don't substitute constants here. Instead,
1937 do it when we emit the following insn.
1939 For example, see the pyr.md file. That machine has signed and
1940 unsigned compares. The compare patterns must check the
1941 following branch insn to see which what kind of compare to
1944 If the previous insn set CC0, substitute constants on it as
1946 if (sets_cc0_p (PATTERN (copy
)) != 0)
1951 try_constants (cc0_insn
, map
);
1953 try_constants (copy
, map
);
1956 try_constants (copy
, map
);
1959 /* Make split induction variable constants `permanent' since we
1960 know there are no backward branches across iteration variable
1961 settings which would invalidate this. */
1962 if (dest_reg_was_split
)
1964 int regno
= REGNO (SET_DEST (pattern
));
1966 if (regno
< VARRAY_SIZE (map
->const_equiv_varray
)
1967 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
1969 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
1974 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
);
1975 copy
= emit_jump_insn (pattern
);
1976 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1978 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
1979 && ! last_iteration
)
1981 /* This is a branch to the beginning of the loop; this is the
1982 last insn being copied; and this is not the last iteration.
1983 In this case, we want to change the original fall through
1984 case to be a branch past the end of the loop, and the
1985 original jump label case to fall_through. */
1987 if (invert_exp (pattern
, copy
))
1989 if (! redirect_exp (&pattern
,
1990 get_label_from_map (map
,
1992 (JUMP_LABEL (insn
))),
1999 rtx lab
= gen_label_rtx ();
2000 /* Can't do it by reversing the jump (probably because we
2001 couldn't reverse the conditions), so emit a new
2002 jump_insn after COPY, and redirect the jump around
2004 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2005 jmp
= emit_barrier_after (jmp
);
2006 emit_label_after (lab
, jmp
);
2007 LABEL_NUSES (lab
) = 0;
2008 if (! redirect_exp (&pattern
,
2009 get_label_from_map (map
,
2011 (JUMP_LABEL (insn
))),
2019 try_constants (cc0_insn
, map
);
2022 try_constants (copy
, map
);
2024 /* Set the jump label of COPY correctly to avoid problems with
2025 later passes of unroll_loop, if INSN had jump label set. */
2026 if (JUMP_LABEL (insn
))
2030 /* Can't use the label_map for every insn, since this may be
2031 the backward branch, and hence the label was not mapped. */
2032 if ((set
= single_set (copy
)))
2034 tem
= SET_SRC (set
);
2035 if (GET_CODE (tem
) == LABEL_REF
)
2036 label
= XEXP (tem
, 0);
2037 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2039 if (XEXP (tem
, 1) != pc_rtx
)
2040 label
= XEXP (XEXP (tem
, 1), 0);
2042 label
= XEXP (XEXP (tem
, 2), 0);
2046 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2047 JUMP_LABEL (copy
) = label
;
2050 /* An unrecognizable jump insn, probably the entry jump
2051 for a switch statement. This label must have been mapped,
2052 so just use the label_map to get the new jump label. */
2054 = get_label_from_map (map
,
2055 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2058 /* If this is a non-local jump, then must increase the label
2059 use count so that the label will not be deleted when the
2060 original jump is deleted. */
2061 LABEL_NUSES (JUMP_LABEL (copy
))++;
2063 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2064 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2066 rtx pat
= PATTERN (copy
);
2067 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2068 int len
= XVECLEN (pat
, diff_vec_p
);
2071 for (i
= 0; i
< len
; i
++)
2072 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2075 /* If this used to be a conditional jump insn but whose branch
2076 direction is now known, we must do something special. */
2077 if (condjump_p (insn
) && !simplejump_p (insn
) && map
->last_pc_value
)
2080 /* If the previous insn set cc0 for us, delete it. */
2081 if (sets_cc0_p (PREV_INSN (copy
)))
2082 delete_insn (PREV_INSN (copy
));
2085 /* If this is now a no-op, delete it. */
2086 if (map
->last_pc_value
== pc_rtx
)
2088 /* Don't let delete_insn delete the label referenced here,
2089 because we might possibly need it later for some other
2090 instruction in the loop. */
2091 if (JUMP_LABEL (copy
))
2092 LABEL_NUSES (JUMP_LABEL (copy
))++;
2094 if (JUMP_LABEL (copy
))
2095 LABEL_NUSES (JUMP_LABEL (copy
))--;
2099 /* Otherwise, this is unconditional jump so we must put a
2100 BARRIER after it. We could do some dead code elimination
2101 here, but jump.c will do it just as well. */
2107 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
);
2108 copy
= emit_call_insn (pattern
);
2109 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2111 /* Because the USAGE information potentially contains objects other
2112 than hard registers, we need to copy it. */
2113 CALL_INSN_FUNCTION_USAGE (copy
)
2114 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
), map
);
2118 try_constants (cc0_insn
, map
);
2121 try_constants (copy
, map
);
2123 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2124 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2125 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2129 /* If this is the loop start label, then we don't need to emit a
2130 copy of this label since no one will use it. */
2132 if (insn
!= start_label
)
2134 copy
= emit_label (get_label_from_map (map
,
2135 CODE_LABEL_NUMBER (insn
)));
2141 copy
= emit_barrier ();
2145 /* VTOP and CONT notes are valid only before the loop exit test.
2146 If placed anywhere else, loop may generate bad code. */
2147 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2148 the associated rtl. We do not want to share the structure in
2151 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2152 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2153 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2154 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2155 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2156 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2157 NOTE_LINE_NUMBER (insn
));
2167 map
->insn_map
[INSN_UID (insn
)] = copy
;
2169 while (insn
!= copy_end
);
2171 /* Now finish coping the REG_NOTES. */
2175 insn
= NEXT_INSN (insn
);
2176 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2177 || GET_CODE (insn
) == CALL_INSN
)
2178 && map
->insn_map
[INSN_UID (insn
)])
2179 final_reg_note_copy (REG_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2181 while (insn
!= copy_end
);
2183 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2184 each of these notes here, since there may be some important ones, such as
2185 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2186 iteration, because the original notes won't be deleted.
2188 We can't use insert_before here, because when from preconditioning,
2189 insert_before points before the loop. We can't use copy_end, because
2190 there may be insns already inserted after it (which we don't want to
2191 copy) when not from preconditioning code. */
2193 if (! last_iteration
)
2195 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2197 /* VTOP notes are valid only before the loop exit test.
2198 If placed anywhere else, loop may generate bad code.
2199 There is no need to test for NOTE_INSN_LOOP_CONT notes
2200 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2201 instructions before the last insn in the loop, and if the
2202 end test is that short, there will be a VTOP note between
2203 the CONT note and the test. */
2204 if (GET_CODE (insn
) == NOTE
2205 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2206 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2207 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
)
2208 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2212 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2213 emit_label (final_label
);
2215 tem
= gen_sequence ();
2217 emit_insn_before (tem
, insert_before
);
2220 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2221 emitted. This will correctly handle the case where the increment value
2222 won't fit in the immediate field of a PLUS insns. */
2225 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2226 rtx dest_reg
, src_reg
, increment
;
2230 result
= expand_binop (GET_MODE (dest_reg
), add_optab
, src_reg
, increment
,
2231 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2233 if (dest_reg
!= result
)
2234 emit_move_insn (dest_reg
, result
);
2237 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2238 is a backward branch in that range that branches to somewhere between
2239 LOOP_START and INSN. Returns 0 otherwise. */
2241 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2242 In practice, this is not a problem, because this function is seldom called,
2243 and uses a negligible amount of CPU time on average. */
2246 back_branch_in_range_p (insn
, loop_start
, loop_end
)
2248 rtx loop_start
, loop_end
;
2250 rtx p
, q
, target_insn
;
2251 rtx orig_loop_end
= loop_end
;
2253 /* Stop before we get to the backward branch at the end of the loop. */
2254 loop_end
= prev_nonnote_insn (loop_end
);
2255 if (GET_CODE (loop_end
) == BARRIER
)
2256 loop_end
= PREV_INSN (loop_end
);
2258 /* Check in case insn has been deleted, search forward for first non
2259 deleted insn following it. */
2260 while (INSN_DELETED_P (insn
))
2261 insn
= NEXT_INSN (insn
);
2263 /* Check for the case where insn is the last insn in the loop. Deal
2264 with the case where INSN was a deleted loop test insn, in which case
2265 it will now be the NOTE_LOOP_END. */
2266 if (insn
== loop_end
|| insn
== orig_loop_end
)
2269 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2271 if (GET_CODE (p
) == JUMP_INSN
)
2273 target_insn
= JUMP_LABEL (p
);
2275 /* Search from loop_start to insn, to see if one of them is
2276 the target_insn. We can't use INSN_LUID comparisons here,
2277 since insn may not have an LUID entry. */
2278 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2279 if (q
== target_insn
)
2287 /* Try to generate the simplest rtx for the expression
2288 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2292 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2293 rtx mult1
, mult2
, add1
;
2294 enum machine_mode mode
;
2299 /* The modes must all be the same. This should always be true. For now,
2300 check to make sure. */
2301 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2302 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2303 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2306 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2307 will be a constant. */
2308 if (GET_CODE (mult1
) == CONST_INT
)
2315 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2317 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2319 /* Again, put the constant second. */
2320 if (GET_CODE (add1
) == CONST_INT
)
2327 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2329 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2334 /* Searches the list of induction struct's for the biv BL, to try to calculate
2335 the total increment value for one iteration of the loop as a constant.
2337 Returns the increment value as an rtx, simplified as much as possible,
2338 if it can be calculated. Otherwise, returns 0. */
2341 biv_total_increment (bl
, loop_start
, loop_end
)
2342 struct iv_class
*bl
;
2343 rtx loop_start
, loop_end
;
2345 struct induction
*v
;
2348 /* For increment, must check every instruction that sets it. Each
2349 instruction must be executed only once each time through the loop.
2350 To verify this, we check that the insn is always executed, and that
2351 there are no backward branches after the insn that branch to before it.
2352 Also, the insn must have a mult_val of one (to make sure it really is
2355 result
= const0_rtx
;
2356 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2358 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2359 && ! v
->maybe_multiple
)
2360 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2368 /* Determine the initial value of the iteration variable, and the amount
2369 that it is incremented each loop. Use the tables constructed by
2370 the strength reduction pass to calculate these values.
2372 Initial_value and/or increment are set to zero if their values could not
2376 iteration_info (iteration_var
, initial_value
, increment
, loop_start
, loop_end
)
2377 rtx iteration_var
, *initial_value
, *increment
;
2378 rtx loop_start
, loop_end
;
2380 struct iv_class
*bl
;
2382 struct induction
*v
;
2385 /* Clear the result values, in case no answer can be found. */
2389 /* The iteration variable can be either a giv or a biv. Check to see
2390 which it is, and compute the variable's initial value, and increment
2391 value if possible. */
2393 /* If this is a new register, can't handle it since we don't have any
2394 reg_iv_type entry for it. */
2395 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
)
2397 if (loop_dump_stream
)
2398 fprintf (loop_dump_stream
,
2399 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2403 /* Reject iteration variables larger than the host wide int size, since they
2404 could result in a number of iterations greater than the range of our
2405 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
2406 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
2407 > HOST_BITS_PER_WIDE_INT
))
2409 if (loop_dump_stream
)
2410 fprintf (loop_dump_stream
,
2411 "Loop unrolling: Iteration var rejected because mode too large.\n");
2414 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
2416 if (loop_dump_stream
)
2417 fprintf (loop_dump_stream
,
2418 "Loop unrolling: Iteration var not an integer.\n");
2421 else if (REG_IV_TYPE (REGNO (iteration_var
)) == BASIC_INDUCT
)
2423 /* When reg_iv_type / reg_iv_info is resized for biv increments
2424 that are turned into givs, reg_biv_class is not resized.
2425 So check here that we don't make an out-of-bounds access. */
2426 if (REGNO (iteration_var
) >= max_reg_before_loop
)
2429 /* Grab initial value, only useful if it is a constant. */
2430 bl
= reg_biv_class
[REGNO (iteration_var
)];
2431 *initial_value
= bl
->initial_value
;
2433 *increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2435 else if (REG_IV_TYPE (REGNO (iteration_var
)) == GENERAL_INDUCT
)
2437 HOST_WIDE_INT offset
= 0;
2438 struct induction
*v
= REG_IV_INFO (REGNO (iteration_var
));
2440 if (REGNO (v
->src_reg
) >= max_reg_before_loop
)
2443 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
2445 /* Increment value is mult_val times the increment value of the biv. */
2447 *increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2450 struct induction
*biv_inc
;
2453 = fold_rtx_mult_add (v
->mult_val
, *increment
, const0_rtx
, v
->mode
);
2454 /* The caller assumes that one full increment has occured at the
2455 first loop test. But that's not true when the biv is incremented
2456 after the giv is set (which is the usual case), e.g.:
2457 i = 6; do {;} while (i++ < 9) .
2458 Therefore, we bias the initial value by subtracting the amount of
2459 the increment that occurs between the giv set and the giv test. */
2460 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
2462 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
2463 offset
-= INTVAL (biv_inc
->add_val
);
2465 offset
*= INTVAL (v
->mult_val
);
2467 if (loop_dump_stream
)
2468 fprintf (loop_dump_stream
,
2469 "Loop unrolling: Giv iterator, initial value bias %ld.\n",
2471 /* Initial value is mult_val times the biv's initial value plus
2472 add_val. Only useful if it is a constant. */
2474 = fold_rtx_mult_add (v
->mult_val
,
2475 plus_constant (bl
->initial_value
, offset
),
2476 v
->add_val
, v
->mode
);
2480 if (loop_dump_stream
)
2481 fprintf (loop_dump_stream
,
2482 "Loop unrolling: Not basic or general induction var.\n");
2488 /* For each biv and giv, determine whether it can be safely split into
2489 a different variable for each unrolled copy of the loop body. If it
2490 is safe to split, then indicate that by saving some useful info
2491 in the splittable_regs array.
2493 If the loop is being completely unrolled, then splittable_regs will hold
2494 the current value of the induction variable while the loop is unrolled.
2495 It must be set to the initial value of the induction variable here.
2496 Otherwise, splittable_regs will hold the difference between the current
2497 value of the induction variable and the value the induction variable had
2498 at the top of the loop. It must be set to the value 0 here.
2500 Returns the total number of instructions that set registers that are
2503 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2504 constant values are unnecessary, since we can easily calculate increment
2505 values in this case even if nothing is constant. The increment value
2506 should not involve a multiply however. */
2508 /* ?? Even if the biv/giv increment values aren't constant, it may still
2509 be beneficial to split the variable if the loop is only unrolled a few
2510 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2513 find_splittable_regs (unroll_type
, loop_start
, loop_end
, end_insert_before
,
2514 unroll_number
, n_iterations
)
2515 enum unroll_types unroll_type
;
2516 rtx loop_start
, loop_end
;
2517 rtx end_insert_before
;
2519 unsigned HOST_WIDE_INT n_iterations
;
2521 struct iv_class
*bl
;
2522 struct induction
*v
;
2524 rtx biv_final_value
;
2528 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
2530 /* Biv_total_increment must return a constant value,
2531 otherwise we can not calculate the split values. */
2533 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2534 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2537 /* The loop must be unrolled completely, or else have a known number
2538 of iterations and only one exit, or else the biv must be dead
2539 outside the loop, or else the final value must be known. Otherwise,
2540 it is unsafe to split the biv since it may not have the proper
2541 value on loop exit. */
2543 /* loop_number_exit_count is non-zero if the loop has an exit other than
2544 a fall through at the end. */
2547 biv_final_value
= 0;
2548 if (unroll_type
!= UNROLL_COMPLETELY
2549 && (loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
2550 || unroll_type
== UNROLL_NAIVE
)
2551 && (uid_luid
[REGNO_LAST_UID (bl
->regno
)] >= INSN_LUID (loop_end
)
2553 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2554 || (uid_luid
[REGNO_FIRST_UID (bl
->regno
)]
2555 < INSN_LUID (bl
->init_insn
))
2556 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2557 && ! (biv_final_value
= final_biv_value (bl
, loop_start
, loop_end
,
2561 /* If any of the insns setting the BIV don't do so with a simple
2562 PLUS, we don't know how to split it. */
2563 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2564 if ((tem
= single_set (v
->insn
)) == 0
2565 || GET_CODE (SET_DEST (tem
)) != REG
2566 || REGNO (SET_DEST (tem
)) != bl
->regno
2567 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2570 /* If final value is non-zero, then must emit an instruction which sets
2571 the value of the biv to the proper value. This is done after
2572 handling all of the givs, since some of them may need to use the
2573 biv's value in their initialization code. */
2575 /* This biv is splittable. If completely unrolling the loop, save
2576 the biv's initial value. Otherwise, save the constant zero. */
2578 if (biv_splittable
== 1)
2580 if (unroll_type
== UNROLL_COMPLETELY
)
2582 /* If the initial value of the biv is itself (i.e. it is too
2583 complicated for strength_reduce to compute), or is a hard
2584 register, or it isn't invariant, then we must create a new
2585 pseudo reg to hold the initial value of the biv. */
2587 if (GET_CODE (bl
->initial_value
) == REG
2588 && (REGNO (bl
->initial_value
) == bl
->regno
2589 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2590 || ! invariant_p (bl
->initial_value
)))
2592 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2594 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2595 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2598 if (loop_dump_stream
)
2599 fprintf (loop_dump_stream
, "Biv %d initial value remapped to %d.\n",
2600 bl
->regno
, REGNO (tem
));
2602 splittable_regs
[bl
->regno
] = tem
;
2605 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2608 splittable_regs
[bl
->regno
] = const0_rtx
;
2610 /* Save the number of instructions that modify the biv, so that
2611 we can treat the last one specially. */
2613 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2614 result
+= bl
->biv_count
;
2616 if (loop_dump_stream
)
2617 fprintf (loop_dump_stream
,
2618 "Biv %d safe to split.\n", bl
->regno
);
2621 /* Check every giv that depends on this biv to see whether it is
2622 splittable also. Even if the biv isn't splittable, givs which
2623 depend on it may be splittable if the biv is live outside the
2624 loop, and the givs aren't. */
2626 result
+= find_splittable_givs (bl
, unroll_type
, loop_start
, loop_end
,
2627 increment
, unroll_number
);
2629 /* If final value is non-zero, then must emit an instruction which sets
2630 the value of the biv to the proper value. This is done after
2631 handling all of the givs, since some of them may need to use the
2632 biv's value in their initialization code. */
2633 if (biv_final_value
)
2635 /* If the loop has multiple exits, emit the insns before the
2636 loop to ensure that it will always be executed no matter
2637 how the loop exits. Otherwise emit the insn after the loop,
2638 since this is slightly more efficient. */
2639 if (! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]])
2640 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2645 /* Create a new register to hold the value of the biv, and then
2646 set the biv to its final value before the loop start. The biv
2647 is set to its final value before loop start to ensure that
2648 this insn will always be executed, no matter how the loop
2650 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2651 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2653 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2655 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2659 if (loop_dump_stream
)
2660 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2661 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2663 /* Set up the mapping from the original biv register to the new
2665 bl
->biv
->src_reg
= tem
;
2672 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2673 for the instruction that is using it. Do not make any changes to that
2677 verify_addresses (v
, giv_inc
, unroll_number
)
2678 struct induction
*v
;
2683 rtx orig_addr
= *v
->location
;
2684 rtx last_addr
= plus_constant (v
->dest_reg
,
2685 INTVAL (giv_inc
) * (unroll_number
- 1));
2687 /* First check to see if either address would fail. Handle the fact
2688 that we have may have a match_dup. */
2689 if (! validate_replace_rtx (*v
->location
, v
->dest_reg
, v
->insn
)
2690 || ! validate_replace_rtx (*v
->location
, last_addr
, v
->insn
))
2693 /* Now put things back the way they were before. This should always
2695 if (! validate_replace_rtx (*v
->location
, orig_addr
, v
->insn
))
2701 /* For every giv based on the biv BL, check to determine whether it is
2702 splittable. This is a subroutine to find_splittable_regs ().
2704 Return the number of instructions that set splittable registers. */
2707 find_splittable_givs (bl
, unroll_type
, loop_start
, loop_end
, increment
,
2709 struct iv_class
*bl
;
2710 enum unroll_types unroll_type
;
2711 rtx loop_start
, loop_end
;
2715 struct induction
*v
, *v2
;
2720 /* Scan the list of givs, and set the same_insn field when there are
2721 multiple identical givs in the same insn. */
2722 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2723 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2724 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2728 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2732 /* Only split the giv if it has already been reduced, or if the loop is
2733 being completely unrolled. */
2734 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2737 /* The giv can be split if the insn that sets the giv is executed once
2738 and only once on every iteration of the loop. */
2739 /* An address giv can always be split. v->insn is just a use not a set,
2740 and hence it does not matter whether it is always executed. All that
2741 matters is that all the biv increments are always executed, and we
2742 won't reach here if they aren't. */
2743 if (v
->giv_type
!= DEST_ADDR
2744 && (! v
->always_computable
2745 || back_branch_in_range_p (v
->insn
, loop_start
, loop_end
)))
2748 /* The giv increment value must be a constant. */
2749 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2751 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2754 /* The loop must be unrolled completely, or else have a known number of
2755 iterations and only one exit, or else the giv must be dead outside
2756 the loop, or else the final value of the giv must be known.
2757 Otherwise, it is not safe to split the giv since it may not have the
2758 proper value on loop exit. */
2760 /* The used outside loop test will fail for DEST_ADDR givs. They are
2761 never used outside the loop anyways, so it is always safe to split a
2765 if (unroll_type
!= UNROLL_COMPLETELY
2766 && (loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
2767 || unroll_type
== UNROLL_NAIVE
)
2768 && v
->giv_type
!= DEST_ADDR
2769 /* The next part is true if the pseudo is used outside the loop.
2770 We assume that this is true for any pseudo created after loop
2771 starts, because we don't have a reg_n_info entry for them. */
2772 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2773 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2774 /* Check for the case where the pseudo is set by a shift/add
2775 sequence, in which case the first insn setting the pseudo
2776 is the first insn of the shift/add sequence. */
2777 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2778 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2779 != INSN_UID (XEXP (tem
, 0)))))
2780 /* Line above always fails if INSN was moved by loop opt. */
2781 || (uid_luid
[REGNO_LAST_UID (REGNO (v
->dest_reg
))]
2782 >= INSN_LUID (loop_end
)))
2783 /* Givs made from biv increments are missed by the above test, so
2784 test explicitly for them. */
2785 && (REGNO (v
->dest_reg
) < first_increment_giv
2786 || REGNO (v
->dest_reg
) > last_increment_giv
)
2787 && ! (final_value
= v
->final_value
))
2791 /* Currently, non-reduced/final-value givs are never split. */
2792 /* Should emit insns after the loop if possible, as the biv final value
2795 /* If the final value is non-zero, and the giv has not been reduced,
2796 then must emit an instruction to set the final value. */
2797 if (final_value
&& !v
->new_reg
)
2799 /* Create a new register to hold the value of the giv, and then set
2800 the giv to its final value before the loop start. The giv is set
2801 to its final value before loop start to ensure that this insn
2802 will always be executed, no matter how we exit. */
2803 tem
= gen_reg_rtx (v
->mode
);
2804 emit_insn_before (gen_move_insn (tem
, v
->dest_reg
), loop_start
);
2805 emit_insn_before (gen_move_insn (v
->dest_reg
, final_value
),
2808 if (loop_dump_stream
)
2809 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2810 REGNO (v
->dest_reg
), REGNO (tem
));
2816 /* This giv is splittable. If completely unrolling the loop, save the
2817 giv's initial value. Otherwise, save the constant zero for it. */
2819 if (unroll_type
== UNROLL_COMPLETELY
)
2821 /* It is not safe to use bl->initial_value here, because it may not
2822 be invariant. It is safe to use the initial value stored in
2823 the splittable_regs array if it is set. In rare cases, it won't
2824 be set, so then we do exactly the same thing as
2825 find_splittable_regs does to get a safe value. */
2826 rtx biv_initial_value
;
2828 if (splittable_regs
[bl
->regno
])
2829 biv_initial_value
= splittable_regs
[bl
->regno
];
2830 else if (GET_CODE (bl
->initial_value
) != REG
2831 || (REGNO (bl
->initial_value
) != bl
->regno
2832 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2833 biv_initial_value
= bl
->initial_value
;
2836 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2838 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2839 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2841 biv_initial_value
= tem
;
2843 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2844 v
->add_val
, v
->mode
);
2851 /* If a giv was combined with another giv, then we can only split
2852 this giv if the giv it was combined with was reduced. This
2853 is because the value of v->new_reg is meaningless in this
2855 if (v
->same
&& ! v
->same
->new_reg
)
2857 if (loop_dump_stream
)
2858 fprintf (loop_dump_stream
,
2859 "giv combined with unreduced giv not split.\n");
2862 /* If the giv is an address destination, it could be something other
2863 than a simple register, these have to be treated differently. */
2864 else if (v
->giv_type
== DEST_REG
)
2866 /* If value is not a constant, register, or register plus
2867 constant, then compute its value into a register before
2868 loop start. This prevents invalid rtx sharing, and should
2869 generate better code. We can use bl->initial_value here
2870 instead of splittable_regs[bl->regno] because this code
2871 is going before the loop start. */
2872 if (unroll_type
== UNROLL_COMPLETELY
2873 && GET_CODE (value
) != CONST_INT
2874 && GET_CODE (value
) != REG
2875 && (GET_CODE (value
) != PLUS
2876 || GET_CODE (XEXP (value
, 0)) != REG
2877 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2879 rtx tem
= gen_reg_rtx (v
->mode
);
2880 record_base_value (REGNO (tem
), v
->add_val
, 0);
2881 emit_iv_add_mult (bl
->initial_value
, v
->mult_val
,
2882 v
->add_val
, tem
, loop_start
);
2886 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2887 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
2891 /* Splitting address givs is useful since it will often allow us
2892 to eliminate some increment insns for the base giv as
2895 /* If the addr giv is combined with a dest_reg giv, then all
2896 references to that dest reg will be remapped, which is NOT
2897 what we want for split addr regs. We always create a new
2898 register for the split addr giv, just to be safe. */
2900 /* If we have multiple identical address givs within a
2901 single instruction, then use a single pseudo reg for
2902 both. This is necessary in case one is a match_dup
2905 v
->const_adjust
= 0;
2909 v
->dest_reg
= v
->same_insn
->dest_reg
;
2910 if (loop_dump_stream
)
2911 fprintf (loop_dump_stream
,
2912 "Sharing address givs in insn %d\n",
2913 INSN_UID (v
->insn
));
2915 /* If multiple address GIVs have been combined with the
2916 same dest_reg GIV, do not create a new register for
2918 else if (unroll_type
!= UNROLL_COMPLETELY
2919 && v
->giv_type
== DEST_ADDR
2920 && v
->same
&& v
->same
->giv_type
== DEST_ADDR
2921 && v
->same
->unrolled
2922 /* combine_givs_p may return true for some cases
2923 where the add and mult values are not equal.
2924 To share a register here, the values must be
2926 && rtx_equal_p (v
->same
->mult_val
, v
->mult_val
)
2927 && rtx_equal_p (v
->same
->add_val
, v
->add_val
)
2928 /* If the memory references have different modes,
2929 then the address may not be valid and we must
2930 not share registers. */
2931 && verify_addresses (v
, giv_inc
, unroll_number
))
2933 v
->dest_reg
= v
->same
->dest_reg
;
2936 else if (unroll_type
!= UNROLL_COMPLETELY
)
2938 /* If not completely unrolling the loop, then create a new
2939 register to hold the split value of the DEST_ADDR giv.
2940 Emit insn to initialize its value before loop start. */
2942 rtx tem
= gen_reg_rtx (v
->mode
);
2943 struct induction
*same
= v
->same
;
2944 rtx new_reg
= v
->new_reg
;
2945 record_base_value (REGNO (tem
), v
->add_val
, 0);
2947 if (same
&& same
->derived_from
)
2949 /* calculate_giv_inc doesn't work for derived givs.
2950 copy_loop_body works around the problem for the
2951 DEST_REG givs themselves, but it can't handle
2952 DEST_ADDR givs that have been combined with
2953 a derived DEST_REG giv.
2954 So Handle V as if the giv from which V->SAME has
2955 been derived has been combined with V.
2956 recombine_givs only derives givs from givs that
2957 are reduced the ordinary, so we need not worry
2958 about same->derived_from being in turn derived. */
2960 same
= same
->derived_from
;
2961 new_reg
= express_from (same
, v
);
2962 new_reg
= replace_rtx (new_reg
, same
->dest_reg
,
2966 /* If the address giv has a constant in its new_reg value,
2967 then this constant can be pulled out and put in value,
2968 instead of being part of the initialization code. */
2970 if (GET_CODE (new_reg
) == PLUS
2971 && GET_CODE (XEXP (new_reg
, 1)) == CONST_INT
)
2974 = plus_constant (tem
, INTVAL (XEXP (new_reg
, 1)));
2976 /* Only succeed if this will give valid addresses.
2977 Try to validate both the first and the last
2978 address resulting from loop unrolling, if
2979 one fails, then can't do const elim here. */
2980 if (verify_addresses (v
, giv_inc
, unroll_number
))
2982 /* Save the negative of the eliminated const, so
2983 that we can calculate the dest_reg's increment
2985 v
->const_adjust
= - INTVAL (XEXP (new_reg
, 1));
2987 new_reg
= XEXP (new_reg
, 0);
2988 if (loop_dump_stream
)
2989 fprintf (loop_dump_stream
,
2990 "Eliminating constant from giv %d\n",
2999 /* If the address hasn't been checked for validity yet, do so
3000 now, and fail completely if either the first or the last
3001 unrolled copy of the address is not a valid address
3002 for the instruction that uses it. */
3003 if (v
->dest_reg
== tem
3004 && ! verify_addresses (v
, giv_inc
, unroll_number
))
3006 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3007 if (v2
->same_insn
== v
)
3010 if (loop_dump_stream
)
3011 fprintf (loop_dump_stream
,
3012 "Invalid address for giv at insn %d\n",
3013 INSN_UID (v
->insn
));
3017 v
->new_reg
= new_reg
;
3020 /* We set this after the address check, to guarantee that
3021 the register will be initialized. */
3024 /* To initialize the new register, just move the value of
3025 new_reg into it. This is not guaranteed to give a valid
3026 instruction on machines with complex addressing modes.
3027 If we can't recognize it, then delete it and emit insns
3028 to calculate the value from scratch. */
3029 emit_insn_before (gen_rtx_SET (VOIDmode
, tem
,
3030 copy_rtx (v
->new_reg
)),
3032 if (recog_memoized (PREV_INSN (loop_start
)) < 0)
3036 /* We can't use bl->initial_value to compute the initial
3037 value, because the loop may have been preconditioned.
3038 We must calculate it from NEW_REG. Try using
3039 force_operand instead of emit_iv_add_mult. */
3040 delete_insn (PREV_INSN (loop_start
));
3043 ret
= force_operand (v
->new_reg
, tem
);
3045 emit_move_insn (tem
, ret
);
3046 sequence
= gen_sequence ();
3048 emit_insn_before (sequence
, loop_start
);
3050 if (loop_dump_stream
)
3051 fprintf (loop_dump_stream
,
3052 "Invalid init insn, rewritten.\n");
3057 v
->dest_reg
= value
;
3059 /* Check the resulting address for validity, and fail
3060 if the resulting address would be invalid. */
3061 if (! verify_addresses (v
, giv_inc
, unroll_number
))
3063 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
3064 if (v2
->same_insn
== v
)
3067 if (loop_dump_stream
)
3068 fprintf (loop_dump_stream
,
3069 "Invalid address for giv at insn %d\n",
3070 INSN_UID (v
->insn
));
3073 if (v
->same
&& v
->same
->derived_from
)
3075 /* Handle V as if the giv from which V->SAME has
3076 been derived has been combined with V. */
3078 v
->same
= v
->same
->derived_from
;
3079 v
->new_reg
= express_from (v
->same
, v
);
3080 v
->new_reg
= replace_rtx (v
->new_reg
, v
->same
->dest_reg
,
3086 /* Store the value of dest_reg into the insn. This sharing
3087 will not be a problem as this insn will always be copied
3090 *v
->location
= v
->dest_reg
;
3092 /* If this address giv is combined with a dest reg giv, then
3093 save the base giv's induction pointer so that we will be
3094 able to handle this address giv properly. The base giv
3095 itself does not have to be splittable. */
3097 if (v
->same
&& v
->same
->giv_type
== DEST_REG
)
3098 addr_combined_regs
[REGNO (v
->same
->new_reg
)] = v
->same
;
3100 if (GET_CODE (v
->new_reg
) == REG
)
3102 /* This giv maybe hasn't been combined with any others.
3103 Make sure that it's giv is marked as splittable here. */
3105 splittable_regs
[REGNO (v
->new_reg
)] = value
;
3106 derived_regs
[REGNO (v
->new_reg
)] = v
->derived_from
!= 0;
3108 /* Make it appear to depend upon itself, so that the
3109 giv will be properly split in the main loop above. */
3113 addr_combined_regs
[REGNO (v
->new_reg
)] = v
;
3117 if (loop_dump_stream
)
3118 fprintf (loop_dump_stream
, "DEST_ADDR giv being split.\n");
3124 /* Currently, unreduced giv's can't be split. This is not too much
3125 of a problem since unreduced giv's are not live across loop
3126 iterations anyways. When unrolling a loop completely though,
3127 it makes sense to reduce&split givs when possible, as this will
3128 result in simpler instructions, and will not require that a reg
3129 be live across loop iterations. */
3131 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
3132 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
3133 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
3139 /* Unreduced givs are only updated once by definition. Reduced givs
3140 are updated as many times as their biv is. Mark it so if this is
3141 a splittable register. Don't need to do anything for address givs
3142 where this may not be a register. */
3144 if (GET_CODE (v
->new_reg
) == REG
)
3148 count
= reg_biv_class
[REGNO (v
->src_reg
)]->biv_count
;
3150 if (count
> 1 && v
->derived_from
)
3151 /* In this case, there is one set where the giv insn was and one
3152 set each after each biv increment. (Most are likely dead.) */
3155 splittable_regs_updates
[REGNO (v
->new_reg
)] = count
;
3160 if (loop_dump_stream
)
3164 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
3166 else if (GET_CODE (v
->dest_reg
) != REG
)
3167 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
3169 regnum
= REGNO (v
->dest_reg
);
3170 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
3171 regnum
, INSN_UID (v
->insn
));
3178 /* Try to prove that the register is dead after the loop exits. Trace every
3179 loop exit looking for an insn that will always be executed, which sets
3180 the register to some value, and appears before the first use of the register
3181 is found. If successful, then return 1, otherwise return 0. */
3183 /* ?? Could be made more intelligent in the handling of jumps, so that
3184 it can search past if statements and other similar structures. */
3187 reg_dead_after_loop (reg
, loop_start
, loop_end
)
3188 rtx reg
, loop_start
, loop_end
;
3193 int label_count
= 0;
3194 int this_loop_num
= uid_loop_num
[INSN_UID (loop_start
)];
3196 /* In addition to checking all exits of this loop, we must also check
3197 all exits of inner nested loops that would exit this loop. We don't
3198 have any way to identify those, so we just give up if there are any
3199 such inner loop exits. */
3201 for (label
= loop_number_exit_labels
[this_loop_num
]; label
;
3202 label
= LABEL_NEXTREF (label
))
3205 if (label_count
!= loop_number_exit_count
[this_loop_num
])
3208 /* HACK: Must also search the loop fall through exit, create a label_ref
3209 here which points to the loop_end, and append the loop_number_exit_labels
3211 label
= gen_rtx_LABEL_REF (VOIDmode
, loop_end
);
3212 LABEL_NEXTREF (label
) = loop_number_exit_labels
[this_loop_num
];
3214 for ( ; label
; label
= LABEL_NEXTREF (label
))
3216 /* Succeed if find an insn which sets the biv or if reach end of
3217 function. Fail if find an insn that uses the biv, or if come to
3218 a conditional jump. */
3220 insn
= NEXT_INSN (XEXP (label
, 0));
3223 code
= GET_CODE (insn
);
3224 if (GET_RTX_CLASS (code
) == 'i')
3228 if (reg_referenced_p (reg
, PATTERN (insn
)))
3231 set
= single_set (insn
);
3232 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
3236 if (code
== JUMP_INSN
)
3238 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3240 else if (! simplejump_p (insn
)
3241 /* Prevent infinite loop following infinite loops. */
3242 || jump_count
++ > 20)
3245 insn
= JUMP_LABEL (insn
);
3248 insn
= NEXT_INSN (insn
);
3252 /* Success, the register is dead on all loop exits. */
3256 /* Try to calculate the final value of the biv, the value it will have at
3257 the end of the loop. If we can do it, return that value. */
3260 final_biv_value (bl
, loop_start
, loop_end
, n_iterations
)
3261 struct iv_class
*bl
;
3262 rtx loop_start
, loop_end
;
3263 unsigned HOST_WIDE_INT n_iterations
;
3267 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3269 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3272 /* The final value for reversed bivs must be calculated differently than
3273 for ordinary bivs. In this case, there is already an insn after the
3274 loop which sets this biv's final value (if necessary), and there are
3275 no other loop exits, so we can return any value. */
3278 if (loop_dump_stream
)
3279 fprintf (loop_dump_stream
,
3280 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3285 /* Try to calculate the final value as initial value + (number of iterations
3286 * increment). For this to work, increment must be invariant, the only
3287 exit from the loop must be the fall through at the bottom (otherwise
3288 it may not have its final value when the loop exits), and the initial
3289 value of the biv must be invariant. */
3291 if (n_iterations
!= 0
3292 && ! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
3293 && invariant_p (bl
->initial_value
))
3295 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
3297 if (increment
&& invariant_p (increment
))
3299 /* Can calculate the loop exit value, emit insns after loop
3300 end to calculate this value into a temporary register in
3301 case it is needed later. */
3303 tem
= gen_reg_rtx (bl
->biv
->mode
);
3304 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3305 /* Make sure loop_end is not the last insn. */
3306 if (NEXT_INSN (loop_end
) == 0)
3307 emit_note_after (NOTE_INSN_DELETED
, loop_end
);
3308 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3309 bl
->initial_value
, tem
, NEXT_INSN (loop_end
));
3311 if (loop_dump_stream
)
3312 fprintf (loop_dump_stream
,
3313 "Final biv value for %d, calculated.\n", bl
->regno
);
3319 /* Check to see if the biv is dead at all loop exits. */
3320 if (reg_dead_after_loop (bl
->biv
->src_reg
, loop_start
, loop_end
))
3322 if (loop_dump_stream
)
3323 fprintf (loop_dump_stream
,
3324 "Final biv value for %d, biv dead after loop exit.\n",
3333 /* Try to calculate the final value of the giv, the value it will have at
3334 the end of the loop. If we can do it, return that value. */
3337 final_giv_value (v
, loop_start
, loop_end
, n_iterations
)
3338 struct induction
*v
;
3339 rtx loop_start
, loop_end
;
3340 unsigned HOST_WIDE_INT n_iterations
;
3342 struct iv_class
*bl
;
3345 rtx insert_before
, seq
;
3347 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
3349 /* The final value for givs which depend on reversed bivs must be calculated
3350 differently than for ordinary givs. In this case, there is already an
3351 insn after the loop which sets this giv's final value (if necessary),
3352 and there are no other loop exits, so we can return any value. */
3355 if (loop_dump_stream
)
3356 fprintf (loop_dump_stream
,
3357 "Final giv value for %d, depends on reversed biv\n",
3358 REGNO (v
->dest_reg
));
3362 /* Try to calculate the final value as a function of the biv it depends
3363 upon. The only exit from the loop must be the fall through at the bottom
3364 (otherwise it may not have its final value when the loop exits). */
3366 /* ??? Can calculate the final giv value by subtracting off the
3367 extra biv increments times the giv's mult_val. The loop must have
3368 only one exit for this to work, but the loop iterations does not need
3371 if (n_iterations
!= 0
3372 && ! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]])
3374 /* ?? It is tempting to use the biv's value here since these insns will
3375 be put after the loop, and hence the biv will have its final value
3376 then. However, this fails if the biv is subsequently eliminated.
3377 Perhaps determine whether biv's are eliminable before trying to
3378 determine whether giv's are replaceable so that we can use the
3379 biv value here if it is not eliminable. */
3381 /* We are emitting code after the end of the loop, so we must make
3382 sure that bl->initial_value is still valid then. It will still
3383 be valid if it is invariant. */
3385 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
3387 if (increment
&& invariant_p (increment
)
3388 && invariant_p (bl
->initial_value
))
3390 /* Can calculate the loop exit value of its biv as
3391 (n_iterations * increment) + initial_value */
3393 /* The loop exit value of the giv is then
3394 (final_biv_value - extra increments) * mult_val + add_val.
3395 The extra increments are any increments to the biv which
3396 occur in the loop after the giv's value is calculated.
3397 We must search from the insn that sets the giv to the end
3398 of the loop to calculate this value. */
3400 insert_before
= NEXT_INSN (loop_end
);
3402 /* Put the final biv value in tem. */
3403 tem
= gen_reg_rtx (bl
->biv
->mode
);
3404 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3405 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3406 bl
->initial_value
, tem
, insert_before
);
3408 /* Subtract off extra increments as we find them. */
3409 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3410 insn
= NEXT_INSN (insn
))
3412 struct induction
*biv
;
3414 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3415 if (biv
->insn
== insn
)
3418 tem
= expand_binop (GET_MODE (tem
), sub_optab
, tem
,
3419 biv
->add_val
, NULL_RTX
, 0,
3421 seq
= gen_sequence ();
3423 emit_insn_before (seq
, insert_before
);
3427 /* Now calculate the giv's final value. */
3428 emit_iv_add_mult (tem
, v
->mult_val
, v
->add_val
, tem
,
3431 if (loop_dump_stream
)
3432 fprintf (loop_dump_stream
,
3433 "Final giv value for %d, calc from biv's value.\n",
3434 REGNO (v
->dest_reg
));
3440 /* Replaceable giv's should never reach here. */
3444 /* Check to see if the biv is dead at all loop exits. */
3445 if (reg_dead_after_loop (v
->dest_reg
, loop_start
, loop_end
))
3447 if (loop_dump_stream
)
3448 fprintf (loop_dump_stream
,
3449 "Final giv value for %d, giv dead after loop exit.\n",
3450 REGNO (v
->dest_reg
));
3459 /* Look back before LOOP_START for then insn that sets REG and return
3460 the equivalent constant if there is a REG_EQUAL note otherwise just
3461 the SET_SRC of REG. */
3464 loop_find_equiv_value (loop_start
, reg
)
3472 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3474 if (GET_CODE (insn
) == CODE_LABEL
)
3477 else if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i'
3478 && reg_set_p (reg
, insn
))
3480 /* We found the last insn before the loop that sets the register.
3481 If it sets the entire register, and has a REG_EQUAL note,
3482 then use the value of the REG_EQUAL note. */
3483 if ((set
= single_set (insn
))
3484 && (SET_DEST (set
) == reg
))
3486 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3488 /* Only use the REG_EQUAL note if it is a constant.
3489 Other things, divide in particular, will cause
3490 problems later if we use them. */
3491 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3492 && CONSTANT_P (XEXP (note
, 0)))
3493 ret
= XEXP (note
, 0);
3495 ret
= SET_SRC (set
);
3504 /* Return a simplified rtx for the expression OP - REG.
3506 REG must appear in OP, and OP must be a register or the sum of a register
3509 Thus, the return value must be const0_rtx or the second term.
3511 The caller is responsible for verifying that REG appears in OP and OP has
3515 subtract_reg_term (op
, reg
)
3520 if (GET_CODE (op
) == PLUS
)
3522 if (XEXP (op
, 0) == reg
)
3523 return XEXP (op
, 1);
3524 else if (XEXP (op
, 1) == reg
)
3525 return XEXP (op
, 0);
3527 /* OP does not contain REG as a term. */
3532 /* Find and return register term common to both expressions OP0 and
3533 OP1 or NULL_RTX if no such term exists. Each expression must be a
3534 REG or a PLUS of a REG. */
3537 find_common_reg_term (op0
, op1
)
3540 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3541 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3548 if (GET_CODE (op0
) == PLUS
)
3549 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3551 op01
= const0_rtx
, op00
= op0
;
3553 if (GET_CODE (op1
) == PLUS
)
3554 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3556 op11
= const0_rtx
, op10
= op1
;
3558 /* Find and return common register term if present. */
3559 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3561 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3565 /* No common register term found. */
3570 /* Calculate the number of loop iterations. Returns the exact number of loop
3571 iterations if it can be calculated, otherwise returns zero. */
3573 unsigned HOST_WIDE_INT
3574 loop_iterations (loop_start
, loop_end
, loop_info
)
3575 rtx loop_start
, loop_end
;
3576 struct loop_info
*loop_info
;
3578 rtx comparison
, comparison_value
;
3579 rtx iteration_var
, initial_value
, increment
, final_value
;
3580 enum rtx_code comparison_code
;
3581 HOST_WIDE_INT abs_inc
;
3582 unsigned HOST_WIDE_INT abs_diff
;
3585 int unsigned_p
, compare_dir
, final_larger
;
3590 loop_info
->n_iterations
= 0;
3591 loop_info
->initial_value
= 0;
3592 loop_info
->initial_equiv_value
= 0;
3593 loop_info
->comparison_value
= 0;
3594 loop_info
->final_value
= 0;
3595 loop_info
->final_equiv_value
= 0;
3596 loop_info
->increment
= 0;
3597 loop_info
->iteration_var
= 0;
3598 loop_info
->unroll_number
= 1;
3599 loop_info
->vtop
= 0;
3601 /* We used to use prev_nonnote_insn here, but that fails because it might
3602 accidentally get the branch for a contained loop if the branch for this
3603 loop was deleted. We can only trust branches immediately before the
3605 last_loop_insn
= PREV_INSN (loop_end
);
3607 /* ??? We should probably try harder to find the jump insn
3608 at the end of the loop. The following code assumes that
3609 the last loop insn is a jump to the top of the loop. */
3610 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3612 if (loop_dump_stream
)
3613 fprintf (loop_dump_stream
,
3614 "Loop iterations: No final conditional branch found.\n");
3618 /* If there is a more than a single jump to the top of the loop
3619 we cannot (easily) determine the iteration count. */
3620 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3622 if (loop_dump_stream
)
3623 fprintf (loop_dump_stream
,
3624 "Loop iterations: Loop has multiple back edges.\n");
3628 /* Find the iteration variable. If the last insn is a conditional
3629 branch, and the insn before tests a register value, make that the
3630 iteration variable. */
3632 comparison
= get_condition_for_loop (last_loop_insn
);
3633 if (comparison
== 0)
3635 if (loop_dump_stream
)
3636 fprintf (loop_dump_stream
,
3637 "Loop iterations: No final comparison found.\n");
3641 /* ??? Get_condition may switch position of induction variable and
3642 invariant register when it canonicalizes the comparison. */
3644 comparison_code
= GET_CODE (comparison
);
3645 iteration_var
= XEXP (comparison
, 0);
3646 comparison_value
= XEXP (comparison
, 1);
3648 /* Check if there is a NOTE_INSN_LOOP_VTOP note. If there is,
3649 that means that this is a for or while style loop, with
3650 a loop exit test at the start. Thus, we can assume that
3651 the loop condition was true when the loop was entered.
3653 We start at the end and search backwards for the previous
3654 NOTE. If there is no NOTE_INSN_LOOP_VTOP for this loop,
3655 the search will stop at the NOTE_INSN_LOOP_CONT. */
3658 vtop
= PREV_INSN (vtop
);
3659 while (GET_CODE (vtop
) != NOTE
3660 || NOTE_LINE_NUMBER (vtop
) > 0
3661 || NOTE_LINE_NUMBER (vtop
) == NOTE_REPEATED_LINE_NUMBER
3662 || NOTE_LINE_NUMBER (vtop
) == NOTE_INSN_DELETED
);
3663 if (NOTE_LINE_NUMBER (vtop
) != NOTE_INSN_LOOP_VTOP
)
3665 loop_info
->vtop
= vtop
;
3667 if (GET_CODE (iteration_var
) != REG
)
3669 if (loop_dump_stream
)
3670 fprintf (loop_dump_stream
,
3671 "Loop iterations: Comparison not against register.\n");
3675 /* The only new registers that care created before loop iterations are
3676 givs made from biv increments, so this should never occur. */
3678 if ((unsigned) REGNO (iteration_var
) >= reg_iv_type
->num_elements
)
3681 iteration_info (iteration_var
, &initial_value
, &increment
,
3682 loop_start
, loop_end
);
3683 if (initial_value
== 0)
3684 /* iteration_info already printed a message. */
3689 switch (comparison_code
)
3704 /* Cannot determine loop iterations with this case. */
3723 /* If the comparison value is an invariant register, then try to find
3724 its value from the insns before the start of the loop. */
3726 final_value
= comparison_value
;
3727 if (GET_CODE (comparison_value
) == REG
&& invariant_p (comparison_value
))
3729 final_value
= loop_find_equiv_value (loop_start
, comparison_value
);
3730 /* If we don't get an invariant final value, we are better
3731 off with the original register. */
3732 if (!invariant_p (final_value
))
3733 final_value
= comparison_value
;
3736 /* Calculate the approximate final value of the induction variable
3737 (on the last successful iteration). The exact final value
3738 depends on the branch operator, and increment sign. It will be
3739 wrong if the iteration variable is not incremented by one each
3740 time through the loop and (comparison_value + off_by_one -
3741 initial_value) % increment != 0.
3742 ??? Note that the final_value may overflow and thus final_larger
3743 will be bogus. A potentially infinite loop will be classified
3744 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3746 final_value
= plus_constant (final_value
, off_by_one
);
3748 /* Save the calculated values describing this loop's bounds, in case
3749 precondition_loop_p will need them later. These values can not be
3750 recalculated inside precondition_loop_p because strength reduction
3751 optimizations may obscure the loop's structure.
3753 These values are only required by precondition_loop_p and insert_bct
3754 whenever the number of iterations cannot be computed at compile time.
3755 Only the difference between final_value and initial_value is
3756 important. Note that final_value is only approximate. */
3757 loop_info
->initial_value
= initial_value
;
3758 loop_info
->comparison_value
= comparison_value
;
3759 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3760 loop_info
->increment
= increment
;
3761 loop_info
->iteration_var
= iteration_var
;
3762 loop_info
->comparison_code
= comparison_code
;
3764 /* Try to determine the iteration count for loops such
3765 as (for i = init; i < init + const; i++). When running the
3766 loop optimization twice, the first pass often converts simple
3767 loops into this form. */
3769 if (REG_P (initial_value
))
3775 reg1
= initial_value
;
3776 if (GET_CODE (final_value
) == PLUS
)
3777 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3779 reg2
= final_value
, const2
= const0_rtx
;
3781 /* Check for initial_value = reg1, final_value = reg2 + const2,
3782 where reg1 != reg2. */
3783 if (REG_P (reg2
) && reg2
!= reg1
)
3787 /* Find what reg1 is equivalent to. Hopefully it will
3788 either be reg2 or reg2 plus a constant. */
3789 temp
= loop_find_equiv_value (loop_start
, reg1
);
3790 if (find_common_reg_term (temp
, reg2
))
3791 initial_value
= temp
;
3794 /* Find what reg2 is equivalent to. Hopefully it will
3795 either be reg1 or reg1 plus a constant. Let's ignore
3796 the latter case for now since it is not so common. */
3797 temp
= loop_find_equiv_value (loop_start
, reg2
);
3798 if (temp
== loop_info
->iteration_var
)
3799 temp
= initial_value
;
3801 final_value
= (const2
== const0_rtx
)
3802 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3805 else if (loop_info
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3809 /* When running the loop optimizer twice, check_dbra_loop
3810 further obfuscates reversible loops of the form:
3811 for (i = init; i < init + const; i++). We often end up with
3812 final_value = 0, initial_value = temp, temp = temp2 - init,
3813 where temp2 = init + const. If the loop has a vtop we
3814 can replace initial_value with const. */
3816 temp
= loop_find_equiv_value (loop_start
, reg1
);
3817 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3819 rtx temp2
= loop_find_equiv_value (loop_start
, XEXP (temp
, 0));
3820 if (GET_CODE (temp2
) == PLUS
3821 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3822 initial_value
= XEXP (temp2
, 1);
3827 /* If have initial_value = reg + const1 and final_value = reg +
3828 const2, then replace initial_value with const1 and final_value
3829 with const2. This should be safe since we are protected by the
3830 initial comparison before entering the loop if we have a vtop.
3831 For example, a + b < a + c is not equivalent to b < c for all a
3832 when using modulo arithmetic.
3834 ??? Without a vtop we could still perform the optimization if we check
3835 the initial and final values carefully. */
3837 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3839 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3840 final_value
= subtract_reg_term (final_value
, reg_term
);
3843 loop_info
->initial_equiv_value
= initial_value
;
3844 loop_info
->final_equiv_value
= final_value
;
3846 /* For EQ comparison loops, we don't have a valid final value.
3847 Check this now so that we won't leave an invalid value if we
3848 return early for any other reason. */
3849 if (comparison_code
== EQ
)
3850 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3854 if (loop_dump_stream
)
3855 fprintf (loop_dump_stream
,
3856 "Loop iterations: Increment value can't be calculated.\n");
3860 if (GET_CODE (increment
) != CONST_INT
)
3862 /* If we have a REG, check to see if REG holds a constant value. */
3863 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3864 clear if it is worthwhile to try to handle such RTL. */
3865 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3866 increment
= loop_find_equiv_value (loop_start
, increment
);
3868 if (GET_CODE (increment
) != CONST_INT
)
3870 if (loop_dump_stream
)
3872 fprintf (loop_dump_stream
,
3873 "Loop iterations: Increment value not constant ");
3874 print_rtl (loop_dump_stream
, increment
);
3875 fprintf (loop_dump_stream
, ".\n");
3879 loop_info
->increment
= increment
;
3882 if (GET_CODE (initial_value
) != CONST_INT
)
3884 if (loop_dump_stream
)
3886 fprintf (loop_dump_stream
,
3887 "Loop iterations: Initial value not constant ");
3888 print_rtl (loop_dump_stream
, initial_value
);
3889 fprintf (loop_dump_stream
, ".\n");
3893 else if (comparison_code
== EQ
)
3895 if (loop_dump_stream
)
3896 fprintf (loop_dump_stream
,
3897 "Loop iterations: EQ comparison loop.\n");
3900 else if (GET_CODE (final_value
) != CONST_INT
)
3902 if (loop_dump_stream
)
3904 fprintf (loop_dump_stream
,
3905 "Loop iterations: Final value not constant ");
3906 print_rtl (loop_dump_stream
, final_value
);
3907 fprintf (loop_dump_stream
, ".\n");
3912 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3915 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3916 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3917 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3918 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3920 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3921 - (INTVAL (final_value
) < INTVAL (initial_value
));
3923 if (INTVAL (increment
) > 0)
3925 else if (INTVAL (increment
) == 0)
3930 /* There are 27 different cases: compare_dir = -1, 0, 1;
3931 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3932 There are 4 normal cases, 4 reverse cases (where the iteration variable
3933 will overflow before the loop exits), 4 infinite loop cases, and 15
3934 immediate exit (0 or 1 iteration depending on loop type) cases.
3935 Only try to optimize the normal cases. */
3937 /* (compare_dir/final_larger/increment_dir)
3938 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3939 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3940 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3941 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3943 /* ?? If the meaning of reverse loops (where the iteration variable
3944 will overflow before the loop exits) is undefined, then could
3945 eliminate all of these special checks, and just always assume
3946 the loops are normal/immediate/infinite. Note that this means
3947 the sign of increment_dir does not have to be known. Also,
3948 since it does not really hurt if immediate exit loops or infinite loops
3949 are optimized, then that case could be ignored also, and hence all
3950 loops can be optimized.
3952 According to ANSI Spec, the reverse loop case result is undefined,
3953 because the action on overflow is undefined.
3955 See also the special test for NE loops below. */
3957 if (final_larger
== increment_dir
&& final_larger
!= 0
3958 && (final_larger
== compare_dir
|| compare_dir
== 0))
3963 if (loop_dump_stream
)
3964 fprintf (loop_dump_stream
,
3965 "Loop iterations: Not normal loop.\n");
3969 /* Calculate the number of iterations, final_value is only an approximation,
3970 so correct for that. Note that abs_diff and n_iterations are
3971 unsigned, because they can be as large as 2^n - 1. */
3973 abs_inc
= INTVAL (increment
);
3975 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
3976 else if (abs_inc
< 0)
3978 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
3984 /* For NE tests, make sure that the iteration variable won't miss
3985 the final value. If abs_diff mod abs_incr is not zero, then the
3986 iteration variable will overflow before the loop exits, and we
3987 can not calculate the number of iterations. */
3988 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
3991 /* Note that the number of iterations could be calculated using
3992 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3993 handle potential overflow of the summation. */
3994 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
3995 return loop_info
->n_iterations
;
3999 /* Replace uses of split bivs with their split pseudo register. This is
4000 for original instructions which remain after loop unrolling without
4004 remap_split_bivs (x
)
4007 register enum rtx_code code
;
4009 register const char *fmt
;
4014 code
= GET_CODE (x
);
4029 /* If non-reduced/final-value givs were split, then this would also
4030 have to remap those givs also. */
4032 if (REGNO (x
) < max_reg_before_loop
4033 && REG_IV_TYPE (REGNO (x
)) == BASIC_INDUCT
)
4034 return reg_biv_class
[REGNO (x
)]->biv
->src_reg
;
4041 fmt
= GET_RTX_FORMAT (code
);
4042 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4045 XEXP (x
, i
) = remap_split_bivs (XEXP (x
, i
));
4049 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4050 XVECEXP (x
, i
, j
) = remap_split_bivs (XVECEXP (x
, i
, j
));
4056 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4057 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4058 return 0. COPY_START is where we can start looking for the insns
4059 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4062 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4063 must dominate LAST_UID.
4065 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4066 may not dominate LAST_UID.
4068 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4069 must dominate LAST_UID. */
4072 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
4079 int passed_jump
= 0;
4080 rtx p
= NEXT_INSN (copy_start
);
4082 while (INSN_UID (p
) != first_uid
)
4084 if (GET_CODE (p
) == JUMP_INSN
)
4086 /* Could not find FIRST_UID. */
4092 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4093 if (GET_RTX_CLASS (GET_CODE (p
)) != 'i'
4094 || ! dead_or_set_regno_p (p
, regno
))
4097 /* FIRST_UID is always executed. */
4098 if (passed_jump
== 0)
4101 while (INSN_UID (p
) != last_uid
)
4103 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4104 can not be sure that FIRST_UID dominates LAST_UID. */
4105 if (GET_CODE (p
) == CODE_LABEL
)
4107 /* Could not find LAST_UID, but we reached the end of the loop, so
4109 else if (p
== copy_end
)
4114 /* FIRST_UID is always executed if LAST_UID is executed. */