1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000
3 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifyable option to control the amount of code expansion,
73 or the percent of loops to consider for unrolling. Etc. */
75 /* ??? Look at the register copies inside the loop to see if they form a
76 simple permutation. If so, iterate the permutation until it gets back to
77 the start state. This is how many times we should unroll the loop, for
78 best results, because then all register copies can be eliminated.
79 For example, the lisp nreverse function should be unrolled 3 times
88 ??? The number of times to unroll the loop may also be based on data
89 references in the loop. For example, if we have a loop that references
90 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
92 /* ??? Add some simple linear equation solving capability so that we can
93 determine the number of loop iterations for more complex loops.
94 For example, consider this loop from gdb
95 #define SWAP_TARGET_AND_HOST(buffer,len)
98 char *p = (char *) buffer;
99 char *q = ((char *) buffer) + len - 1;
100 int iterations = (len + 1) >> 1;
102 for (p; p < q; p++, q--;)
110 start value = p = &buffer + current_iteration
111 end value = q = &buffer + len - 1 - current_iteration
112 Given the loop exit test of "p < q", then there must be "q - p" iterations,
113 set equal to zero and solve for number of iterations:
114 q - p = len - 1 - 2*current_iteration = 0
115 current_iteration = (len - 1) / 2
116 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
117 iterations of this loop. */
119 /* ??? Currently, no labels are marked as loop invariant when doing loop
120 unrolling. This is because an insn inside the loop, that loads the address
121 of a label inside the loop into a register, could be moved outside the loop
122 by the invariant code motion pass if labels were invariant. If the loop
123 is subsequently unrolled, the code will be wrong because each unrolled
124 body of the loop will use the same address, whereas each actually needs a
125 different address. A case where this happens is when a loop containing
126 a switch statement is unrolled.
128 It would be better to let labels be considered invariant. When we
129 unroll loops here, check to see if any insns using a label local to the
130 loop were moved before the loop. If so, then correct the problem, by
131 moving the insn back into the loop, or perhaps replicate the insn before
132 the loop, one copy for each time the loop is unrolled. */
134 /* The prime factors looked for when trying to unroll a loop by some
135 number which is modulo the total number of iterations. Just checking
136 for these 4 prime factors will find at least one factor for 75% of
137 all numbers theoretically. Practically speaking, this will succeed
138 almost all of the time since loops are generally a multiple of 2
141 #define NUM_FACTORS 4
143 struct _factor
{ int factor
, count
; }
144 factors
[NUM_FACTORS
] = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
146 /* Describes the different types of loop unrolling performed. */
159 #include "insn-config.h"
160 #include "integrate.h"
164 #include "function.h"
168 #include "hard-reg-set.h"
169 #include "basic-block.h"
171 /* This controls which loops are unrolled, and by how much we unroll
174 #ifndef MAX_UNROLLED_INSNS
175 #define MAX_UNROLLED_INSNS 100
178 /* Indexed by register number, if non-zero, then it contains a pointer
179 to a struct induction for a DEST_REG giv which has been combined with
180 one of more address givs. This is needed because whenever such a DEST_REG
181 giv is modified, we must modify the value of all split address givs
182 that were combined with this DEST_REG giv. */
184 static struct induction
**addr_combined_regs
;
186 /* Indexed by register number, if this is a splittable induction variable,
187 then this will hold the current value of the register, which depends on the
190 static rtx
*splittable_regs
;
192 /* Indexed by register number, if this is a splittable induction variable,
193 then this will hold the number of instructions in the loop that modify
194 the induction variable. Used to ensure that only the last insn modifying
195 a split iv will update the original iv of the dest. */
197 static int *splittable_regs_updates
;
199 /* Forward declarations. */
201 static void init_reg_map
PARAMS ((struct inline_remap
*, int));
202 static rtx calculate_giv_inc
PARAMS ((rtx
, rtx
, unsigned int));
203 static rtx initial_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
204 static void final_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
205 static void copy_loop_body
PARAMS ((struct loop
*, rtx
, rtx
,
206 struct inline_remap
*, rtx
, int,
207 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
208 static int find_splittable_regs
PARAMS ((const struct loop
*,
209 enum unroll_types
, rtx
, int));
210 static int find_splittable_givs
PARAMS ((const struct loop
*,
211 struct iv_class
*, enum unroll_types
,
213 static int reg_dead_after_loop
PARAMS ((const struct loop
*, rtx
));
214 static rtx fold_rtx_mult_add
PARAMS ((rtx
, rtx
, rtx
, enum machine_mode
));
215 static int verify_addresses
PARAMS ((struct induction
*, rtx
, int));
216 static rtx remap_split_bivs
PARAMS ((struct loop
*, rtx
));
217 static rtx find_common_reg_term
PARAMS ((rtx
, rtx
));
218 static rtx subtract_reg_term
PARAMS ((rtx
, rtx
));
219 static rtx loop_find_equiv_value
PARAMS ((const struct loop
*, rtx
));
220 static rtx ujump_to_loop_cont
PARAMS ((rtx
, rtx
));
222 /* Try to unroll one loop and split induction variables in the loop.
224 The loop is described by the arguments LOOP and INSN_COUNT.
225 END_INSERT_BEFORE indicates where insns should be added which need
226 to be executed when the loop falls through. STRENGTH_REDUCTION_P
227 indicates whether information generated in the strength reduction
230 This function is intended to be called from within `strength_reduce'
234 unroll_loop (loop
, insn_count
, end_insert_before
, strength_reduce_p
)
237 rtx end_insert_before
;
238 int strength_reduce_p
;
240 struct loop_info
*loop_info
= LOOP_INFO (loop
);
241 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
244 unsigned HOST_WIDE_INT temp
;
245 int unroll_number
= 1;
246 rtx copy_start
, copy_end
;
247 rtx insn
, sequence
, pattern
, tem
;
248 int max_labelno
, max_insnno
;
250 struct inline_remap
*map
;
251 char *local_label
= NULL
;
253 unsigned int max_local_regnum
;
254 unsigned int maxregnum
;
258 int splitting_not_safe
= 0;
259 enum unroll_types unroll_type
= UNROLL_NAIVE
;
260 int loop_preconditioned
= 0;
262 /* This points to the last real insn in the loop, which should be either
263 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
266 rtx loop_start
= loop
->start
;
267 rtx loop_end
= loop
->end
;
269 /* Don't bother unrolling huge loops. Since the minimum factor is
270 two, loops greater than one half of MAX_UNROLLED_INSNS will never
272 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
274 if (loop_dump_stream
)
275 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
279 /* When emitting debugger info, we can't unroll loops with unequal numbers
280 of block_beg and block_end notes, because that would unbalance the block
281 structure of the function. This can happen as a result of the
282 "if (foo) bar; else break;" optimization in jump.c. */
283 /* ??? Gcc has a general policy that -g is never supposed to change the code
284 that the compiler emits, so we must disable this optimization always,
285 even if debug info is not being output. This is rare, so this should
286 not be a significant performance problem. */
288 if (1 /* write_symbols != NO_DEBUG */)
290 int block_begins
= 0;
293 for (insn
= loop_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
295 if (GET_CODE (insn
) == NOTE
)
297 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
)
299 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
301 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_BEG
302 || NOTE_LINE_NUMBER (insn
) == NOTE_INSN_EH_REGION_END
)
304 /* Note, would be nice to add code to unroll EH
305 regions, but until that time, we punt (don't
306 unroll). For the proper way of doing it, see
307 expand_inline_function. */
309 if (loop_dump_stream
)
310 fprintf (loop_dump_stream
,
311 "Unrolling failure: cannot unroll EH regions.\n");
317 if (block_begins
!= block_ends
)
319 if (loop_dump_stream
)
320 fprintf (loop_dump_stream
,
321 "Unrolling failure: Unbalanced block notes.\n");
326 /* Determine type of unroll to perform. Depends on the number of iterations
327 and the size of the loop. */
329 /* If there is no strength reduce info, then set
330 loop_info->n_iterations to zero. This can happen if
331 strength_reduce can't find any bivs in the loop. A value of zero
332 indicates that the number of iterations could not be calculated. */
334 if (! strength_reduce_p
)
335 loop_info
->n_iterations
= 0;
337 if (loop_dump_stream
&& loop_info
->n_iterations
> 0)
339 fputs ("Loop unrolling: ", loop_dump_stream
);
340 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
341 loop_info
->n_iterations
);
342 fputs (" iterations.\n", loop_dump_stream
);
345 /* Find and save a pointer to the last nonnote insn in the loop. */
347 last_loop_insn
= prev_nonnote_insn (loop_end
);
349 /* Calculate how many times to unroll the loop. Indicate whether or
350 not the loop is being completely unrolled. */
352 if (loop_info
->n_iterations
== 1)
354 /* Handle the case where the loop begins with an unconditional
355 jump to the loop condition. Make sure to delete the jump
356 insn, otherwise the loop body will never execute. */
358 rtx ujump
= ujump_to_loop_cont (loop
->start
, loop
->cont
);
362 /* If number of iterations is exactly 1, then eliminate the compare and
363 branch at the end of the loop since they will never be taken.
364 Then return, since no other action is needed here. */
366 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
367 don't do anything. */
369 if (GET_CODE (last_loop_insn
) == BARRIER
)
371 /* Delete the jump insn. This will delete the barrier also. */
372 delete_insn (PREV_INSN (last_loop_insn
));
374 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
377 rtx prev
= PREV_INSN (last_loop_insn
);
379 delete_insn (last_loop_insn
);
381 /* The immediately preceding insn may be a compare which must be
383 if (sets_cc0_p (prev
))
388 /* Remove the loop notes since this is no longer a loop. */
390 delete_insn (loop
->vtop
);
392 delete_insn (loop
->cont
);
394 delete_insn (loop_start
);
396 delete_insn (loop_end
);
400 else if (loop_info
->n_iterations
> 0
401 /* Avoid overflow in the next expression. */
402 && loop_info
->n_iterations
< MAX_UNROLLED_INSNS
403 && loop_info
->n_iterations
* insn_count
< MAX_UNROLLED_INSNS
)
405 unroll_number
= loop_info
->n_iterations
;
406 unroll_type
= UNROLL_COMPLETELY
;
408 else if (loop_info
->n_iterations
> 0)
410 /* Try to factor the number of iterations. Don't bother with the
411 general case, only using 2, 3, 5, and 7 will get 75% of all
412 numbers theoretically, and almost all in practice. */
414 for (i
= 0; i
< NUM_FACTORS
; i
++)
415 factors
[i
].count
= 0;
417 temp
= loop_info
->n_iterations
;
418 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
419 while (temp
% factors
[i
].factor
== 0)
422 temp
= temp
/ factors
[i
].factor
;
425 /* Start with the larger factors first so that we generally
426 get lots of unrolling. */
430 for (i
= 3; i
>= 0; i
--)
431 while (factors
[i
].count
--)
433 if (temp
* factors
[i
].factor
< MAX_UNROLLED_INSNS
)
435 unroll_number
*= factors
[i
].factor
;
436 temp
*= factors
[i
].factor
;
442 /* If we couldn't find any factors, then unroll as in the normal
444 if (unroll_number
== 1)
446 if (loop_dump_stream
)
447 fprintf (loop_dump_stream
, "Loop unrolling: No factors found.\n");
450 unroll_type
= UNROLL_MODULO
;
453 /* Default case, calculate number of times to unroll loop based on its
455 if (unroll_type
== UNROLL_NAIVE
)
457 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
459 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
465 /* Now we know how many times to unroll the loop. */
467 if (loop_dump_stream
)
468 fprintf (loop_dump_stream
, "Unrolling loop %d times.\n", unroll_number
);
470 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
472 /* Loops of these types can start with jump down to the exit condition
473 in rare circumstances.
475 Consider a pair of nested loops where the inner loop is part
476 of the exit code for the outer loop.
478 In this case jump.c will not duplicate the exit test for the outer
479 loop, so it will start with a jump to the exit code.
481 Then consider if the inner loop turns out to iterate once and
482 only once. We will end up deleting the jumps associated with
483 the inner loop. However, the loop notes are not removed from
484 the instruction stream.
486 And finally assume that we can compute the number of iterations
489 In this case unroll may want to unroll the outer loop even though
490 it starts with a jump to the outer loop's exit code.
492 We could try to optimize this case, but it hardly seems worth it.
493 Just return without unrolling the loop in such cases. */
496 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
497 insn
= NEXT_INSN (insn
);
498 if (GET_CODE (insn
) == JUMP_INSN
)
502 if (unroll_type
== UNROLL_COMPLETELY
)
504 /* Completely unrolling the loop: Delete the compare and branch at
505 the end (the last two instructions). This delete must done at the
506 very end of loop unrolling, to avoid problems with calls to
507 back_branch_in_range_p, which is called by find_splittable_regs.
508 All increments of splittable bivs/givs are changed to load constant
511 copy_start
= loop_start
;
513 /* Set insert_before to the instruction immediately after the JUMP_INSN
514 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
515 the loop will be correctly handled by copy_loop_body. */
516 insert_before
= NEXT_INSN (last_loop_insn
);
518 /* Set copy_end to the insn before the jump at the end of the loop. */
519 if (GET_CODE (last_loop_insn
) == BARRIER
)
520 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
521 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
523 copy_end
= PREV_INSN (last_loop_insn
);
525 /* The instruction immediately before the JUMP_INSN may be a compare
526 instruction which we do not want to copy. */
527 if (sets_cc0_p (PREV_INSN (copy_end
)))
528 copy_end
= PREV_INSN (copy_end
);
533 /* We currently can't unroll a loop if it doesn't end with a
534 JUMP_INSN. There would need to be a mechanism that recognizes
535 this case, and then inserts a jump after each loop body, which
536 jumps to after the last loop body. */
537 if (loop_dump_stream
)
538 fprintf (loop_dump_stream
,
539 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
543 else if (unroll_type
== UNROLL_MODULO
)
545 /* Partially unrolling the loop: The compare and branch at the end
546 (the last two instructions) must remain. Don't copy the compare
547 and branch instructions at the end of the loop. Insert the unrolled
548 code immediately before the compare/branch at the end so that the
549 code will fall through to them as before. */
551 copy_start
= loop_start
;
553 /* Set insert_before to the jump insn at the end of the loop.
554 Set copy_end to before the jump insn at the end of the loop. */
555 if (GET_CODE (last_loop_insn
) == BARRIER
)
557 insert_before
= PREV_INSN (last_loop_insn
);
558 copy_end
= PREV_INSN (insert_before
);
560 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
562 insert_before
= last_loop_insn
;
564 /* The instruction immediately before the JUMP_INSN may be a compare
565 instruction which we do not want to copy or delete. */
566 if (sets_cc0_p (PREV_INSN (insert_before
)))
567 insert_before
= PREV_INSN (insert_before
);
569 copy_end
= PREV_INSN (insert_before
);
573 /* We currently can't unroll a loop if it doesn't end with a
574 JUMP_INSN. There would need to be a mechanism that recognizes
575 this case, and then inserts a jump after each loop body, which
576 jumps to after the last loop body. */
577 if (loop_dump_stream
)
578 fprintf (loop_dump_stream
,
579 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
585 /* Normal case: Must copy the compare and branch instructions at the
588 if (GET_CODE (last_loop_insn
) == BARRIER
)
590 /* Loop ends with an unconditional jump and a barrier.
591 Handle this like above, don't copy jump and barrier.
592 This is not strictly necessary, but doing so prevents generating
593 unconditional jumps to an immediately following label.
595 This will be corrected below if the target of this jump is
596 not the start_label. */
598 insert_before
= PREV_INSN (last_loop_insn
);
599 copy_end
= PREV_INSN (insert_before
);
601 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
603 /* Set insert_before to immediately after the JUMP_INSN, so that
604 NOTEs at the end of the loop will be correctly handled by
606 insert_before
= NEXT_INSN (last_loop_insn
);
607 copy_end
= last_loop_insn
;
611 /* We currently can't unroll a loop if it doesn't end with a
612 JUMP_INSN. There would need to be a mechanism that recognizes
613 this case, and then inserts a jump after each loop body, which
614 jumps to after the last loop body. */
615 if (loop_dump_stream
)
616 fprintf (loop_dump_stream
,
617 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
621 /* If copying exit test branches because they can not be eliminated,
622 then must convert the fall through case of the branch to a jump past
623 the end of the loop. Create a label to emit after the loop and save
624 it for later use. Do not use the label after the loop, if any, since
625 it might be used by insns outside the loop, or there might be insns
626 added before it later by final_[bg]iv_value which must be after
627 the real exit label. */
628 exit_label
= gen_label_rtx ();
631 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
632 insn
= NEXT_INSN (insn
);
634 if (GET_CODE (insn
) == JUMP_INSN
)
636 /* The loop starts with a jump down to the exit condition test.
637 Start copying the loop after the barrier following this
639 copy_start
= NEXT_INSN (insn
);
641 /* Splitting induction variables doesn't work when the loop is
642 entered via a jump to the bottom, because then we end up doing
643 a comparison against a new register for a split variable, but
644 we did not execute the set insn for the new register because
645 it was skipped over. */
646 splitting_not_safe
= 1;
647 if (loop_dump_stream
)
648 fprintf (loop_dump_stream
,
649 "Splitting not safe, because loop not entered at top.\n");
652 copy_start
= loop_start
;
655 /* This should always be the first label in the loop. */
656 start_label
= NEXT_INSN (copy_start
);
657 /* There may be a line number note and/or a loop continue note here. */
658 while (GET_CODE (start_label
) == NOTE
)
659 start_label
= NEXT_INSN (start_label
);
660 if (GET_CODE (start_label
) != CODE_LABEL
)
662 /* This can happen as a result of jump threading. If the first insns in
663 the loop test the same condition as the loop's backward jump, or the
664 opposite condition, then the backward jump will be modified to point
665 to elsewhere, and the loop's start label is deleted.
667 This case currently can not be handled by the loop unrolling code. */
669 if (loop_dump_stream
)
670 fprintf (loop_dump_stream
,
671 "Unrolling failure: unknown insns between BEG note and loop label.\n");
674 if (LABEL_NAME (start_label
))
676 /* The jump optimization pass must have combined the original start label
677 with a named label for a goto. We can't unroll this case because
678 jumps which go to the named label must be handled differently than
679 jumps to the loop start, and it is impossible to differentiate them
681 if (loop_dump_stream
)
682 fprintf (loop_dump_stream
,
683 "Unrolling failure: loop start label is gone\n");
687 if (unroll_type
== UNROLL_NAIVE
688 && GET_CODE (last_loop_insn
) == BARRIER
689 && GET_CODE (PREV_INSN (last_loop_insn
)) == JUMP_INSN
690 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
692 /* In this case, we must copy the jump and barrier, because they will
693 not be converted to jumps to an immediately following label. */
695 insert_before
= NEXT_INSN (last_loop_insn
);
696 copy_end
= last_loop_insn
;
699 if (unroll_type
== UNROLL_NAIVE
700 && GET_CODE (last_loop_insn
) == JUMP_INSN
701 && start_label
!= JUMP_LABEL (last_loop_insn
))
703 /* ??? The loop ends with a conditional branch that does not branch back
704 to the loop start label. In this case, we must emit an unconditional
705 branch to the loop exit after emitting the final branch.
706 copy_loop_body does not have support for this currently, so we
707 give up. It doesn't seem worthwhile to unroll anyways since
708 unrolling would increase the number of branch instructions
710 if (loop_dump_stream
)
711 fprintf (loop_dump_stream
,
712 "Unrolling failure: final conditional branch not to loop start\n");
716 /* Allocate a translation table for the labels and insn numbers.
717 They will be filled in as we copy the insns in the loop. */
719 max_labelno
= max_label_num ();
720 max_insnno
= get_max_uid ();
722 /* Various paths through the unroll code may reach the "egress" label
723 without initializing fields within the map structure.
725 To be safe, we use xcalloc to zero the memory. */
726 map
= (struct inline_remap
*) xcalloc (1, sizeof (struct inline_remap
));
728 /* Allocate the label map. */
732 map
->label_map
= (rtx
*) xmalloc (max_labelno
* sizeof (rtx
));
734 local_label
= (char *) xcalloc (max_labelno
, sizeof (char));
737 /* Search the loop and mark all local labels, i.e. the ones which have to
738 be distinct labels when copied. For all labels which might be
739 non-local, set their label_map entries to point to themselves.
740 If they happen to be local their label_map entries will be overwritten
741 before the loop body is copied. The label_map entries for local labels
742 will be set to a different value each time the loop body is copied. */
744 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
748 if (GET_CODE (insn
) == CODE_LABEL
)
749 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
750 else if (GET_CODE (insn
) == JUMP_INSN
)
752 if (JUMP_LABEL (insn
))
753 set_label_in_map (map
,
754 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)),
756 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
757 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
759 rtx pat
= PATTERN (insn
);
760 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
761 int len
= XVECLEN (pat
, diff_vec_p
);
764 for (i
= 0; i
< len
; i
++)
766 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
767 set_label_in_map (map
, CODE_LABEL_NUMBER (label
), label
);
771 else if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)))
772 set_label_in_map (map
, CODE_LABEL_NUMBER (XEXP (note
, 0)),
776 /* Allocate space for the insn map. */
778 map
->insn_map
= (rtx
*) xmalloc (max_insnno
* sizeof (rtx
));
780 /* Set this to zero, to indicate that we are doing loop unrolling,
781 not function inlining. */
782 map
->inline_target
= 0;
784 /* The register and constant maps depend on the number of registers
785 present, so the final maps can't be created until after
786 find_splittable_regs is called. However, they are needed for
787 preconditioning, so we create temporary maps when preconditioning
790 /* The preconditioning code may allocate two new pseudo registers. */
791 maxregnum
= max_reg_num ();
793 /* local_regno is only valid for regnos < max_local_regnum. */
794 max_local_regnum
= maxregnum
;
796 /* Allocate and zero out the splittable_regs and addr_combined_regs
797 arrays. These must be zeroed here because they will be used if
798 loop preconditioning is performed, and must be zero for that case.
800 It is safe to do this here, since the extra registers created by the
801 preconditioning code and find_splittable_regs will never be used
802 to access the splittable_regs[] and addr_combined_regs[] arrays. */
804 splittable_regs
= (rtx
*) xcalloc (maxregnum
, sizeof (rtx
));
805 splittable_regs_updates
= (int *) xcalloc (maxregnum
, sizeof (int));
807 = (struct induction
**) xcalloc (maxregnum
, sizeof (struct induction
*));
808 local_regno
= (char *) xcalloc (maxregnum
, sizeof (char));
810 /* Mark all local registers, i.e. the ones which are referenced only
812 if (INSN_UID (copy_end
) < max_uid_for_loop
)
814 int copy_start_luid
= INSN_LUID (copy_start
);
815 int copy_end_luid
= INSN_LUID (copy_end
);
817 /* If a register is used in the jump insn, we must not duplicate it
818 since it will also be used outside the loop. */
819 if (GET_CODE (copy_end
) == JUMP_INSN
)
822 /* If we have a target that uses cc0, then we also must not duplicate
823 the insn that sets cc0 before the jump insn, if one is present. */
825 if (GET_CODE (copy_end
) == JUMP_INSN
826 && sets_cc0_p (PREV_INSN (copy_end
)))
830 /* If copy_start points to the NOTE that starts the loop, then we must
831 use the next luid, because invariant pseudo-regs moved out of the loop
832 have their lifetimes modified to start here, but they are not safe
834 if (copy_start
== loop_start
)
837 /* If a pseudo's lifetime is entirely contained within this loop, then we
838 can use a different pseudo in each unrolled copy of the loop. This
839 results in better code. */
840 /* We must limit the generic test to max_reg_before_loop, because only
841 these pseudo registers have valid regno_first_uid info. */
842 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_reg_before_loop
; ++r
)
843 if (REGNO_FIRST_UID (r
) > 0 && REGNO_FIRST_UID (r
) <= max_uid_for_loop
844 && uid_luid
[REGNO_FIRST_UID (r
)] >= copy_start_luid
845 && REGNO_LAST_UID (r
) > 0 && REGNO_LAST_UID (r
) <= max_uid_for_loop
846 && uid_luid
[REGNO_LAST_UID (r
)] <= copy_end_luid
)
848 /* However, we must also check for loop-carried dependencies.
849 If the value the pseudo has at the end of iteration X is
850 used by iteration X+1, then we can not use a different pseudo
851 for each unrolled copy of the loop. */
852 /* A pseudo is safe if regno_first_uid is a set, and this
853 set dominates all instructions from regno_first_uid to
855 /* ??? This check is simplistic. We would get better code if
856 this check was more sophisticated. */
857 if (set_dominates_use (r
, REGNO_FIRST_UID (r
), REGNO_LAST_UID (r
),
858 copy_start
, copy_end
))
861 if (loop_dump_stream
)
864 fprintf (loop_dump_stream
, "Marked reg %d as local\n", r
);
866 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
872 /* If this loop requires exit tests when unrolled, check to see if we
873 can precondition the loop so as to make the exit tests unnecessary.
874 Just like variable splitting, this is not safe if the loop is entered
875 via a jump to the bottom. Also, can not do this if no strength
876 reduce info, because precondition_loop_p uses this info. */
878 /* Must copy the loop body for preconditioning before the following
879 find_splittable_regs call since that will emit insns which need to
880 be after the preconditioned loop copies, but immediately before the
881 unrolled loop copies. */
883 /* Also, it is not safe to split induction variables for the preconditioned
884 copies of the loop body. If we split induction variables, then the code
885 assumes that each induction variable can be represented as a function
886 of its initial value and the loop iteration number. This is not true
887 in this case, because the last preconditioned copy of the loop body
888 could be any iteration from the first up to the `unroll_number-1'th,
889 depending on the initial value of the iteration variable. Therefore
890 we can not split induction variables here, because we can not calculate
891 their value. Hence, this code must occur before find_splittable_regs
894 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
896 rtx initial_value
, final_value
, increment
;
897 enum machine_mode mode
;
899 if (precondition_loop_p (loop
,
900 &initial_value
, &final_value
, &increment
,
905 int abs_inc
, neg_inc
;
907 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
909 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
, maxregnum
,
910 "unroll_loop_precondition");
911 global_const_equiv_varray
= map
->const_equiv_varray
;
913 init_reg_map (map
, maxregnum
);
915 /* Limit loop unrolling to 4, since this will make 7 copies of
917 if (unroll_number
> 4)
920 /* Save the absolute value of the increment, and also whether or
921 not it is negative. */
923 abs_inc
= INTVAL (increment
);
932 /* Calculate the difference between the final and initial values.
933 Final value may be a (plus (reg x) (const_int 1)) rtx.
934 Let the following cse pass simplify this if initial value is
937 We must copy the final and initial values here to avoid
938 improperly shared rtl. */
940 diff
= expand_binop (mode
, sub_optab
, copy_rtx (final_value
),
941 copy_rtx (initial_value
), NULL_RTX
, 0,
944 /* Now calculate (diff % (unroll * abs (increment))) by using an
946 diff
= expand_binop (GET_MODE (diff
), and_optab
, diff
,
947 GEN_INT (unroll_number
* abs_inc
- 1),
948 NULL_RTX
, 0, OPTAB_LIB_WIDEN
);
950 /* Now emit a sequence of branches to jump to the proper precond
953 labels
= (rtx
*) xmalloc (sizeof (rtx
) * unroll_number
);
954 for (i
= 0; i
< unroll_number
; i
++)
955 labels
[i
] = gen_label_rtx ();
957 /* Check for the case where the initial value is greater than or
958 equal to the final value. In that case, we want to execute
959 exactly one loop iteration. The code below will fail for this
960 case. This check does not apply if the loop has a NE
961 comparison at the end. */
963 if (loop_info
->comparison_code
!= NE
)
965 emit_cmp_and_jump_insns (initial_value
, final_value
,
967 NULL_RTX
, mode
, 0, 0, labels
[1]);
968 JUMP_LABEL (get_last_insn ()) = labels
[1];
969 LABEL_NUSES (labels
[1])++;
972 /* Assuming the unroll_number is 4, and the increment is 2, then
973 for a negative increment: for a positive increment:
974 diff = 0,1 precond 0 diff = 0,7 precond 0
975 diff = 2,3 precond 3 diff = 1,2 precond 1
976 diff = 4,5 precond 2 diff = 3,4 precond 2
977 diff = 6,7 precond 1 diff = 5,6 precond 3 */
979 /* We only need to emit (unroll_number - 1) branches here, the
980 last case just falls through to the following code. */
982 /* ??? This would give better code if we emitted a tree of branches
983 instead of the current linear list of branches. */
985 for (i
= 0; i
< unroll_number
- 1; i
++)
988 enum rtx_code cmp_code
;
990 /* For negative increments, must invert the constant compared
991 against, except when comparing against zero. */
999 cmp_const
= unroll_number
- i
;
1008 emit_cmp_and_jump_insns (diff
, GEN_INT (abs_inc
* cmp_const
),
1009 cmp_code
, NULL_RTX
, mode
, 0, 0,
1011 JUMP_LABEL (get_last_insn ()) = labels
[i
];
1012 LABEL_NUSES (labels
[i
])++;
1015 /* If the increment is greater than one, then we need another branch,
1016 to handle other cases equivalent to 0. */
1018 /* ??? This should be merged into the code above somehow to help
1019 simplify the code here, and reduce the number of branches emitted.
1020 For the negative increment case, the branch here could easily
1021 be merged with the `0' case branch above. For the positive
1022 increment case, it is not clear how this can be simplified. */
1027 enum rtx_code cmp_code
;
1031 cmp_const
= abs_inc
- 1;
1036 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
1040 emit_cmp_and_jump_insns (diff
, GEN_INT (cmp_const
), cmp_code
,
1041 NULL_RTX
, mode
, 0, 0, labels
[0]);
1042 JUMP_LABEL (get_last_insn ()) = labels
[0];
1043 LABEL_NUSES (labels
[0])++;
1046 sequence
= gen_sequence ();
1048 emit_insn_before (sequence
, loop_start
);
1050 /* Only the last copy of the loop body here needs the exit
1051 test, so set copy_end to exclude the compare/branch here,
1052 and then reset it inside the loop when get to the last
1055 if (GET_CODE (last_loop_insn
) == BARRIER
)
1056 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1057 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1059 copy_end
= PREV_INSN (last_loop_insn
);
1061 /* The immediately preceding insn may be a compare which
1062 we do not want to copy. */
1063 if (sets_cc0_p (PREV_INSN (copy_end
)))
1064 copy_end
= PREV_INSN (copy_end
);
1070 for (i
= 1; i
< unroll_number
; i
++)
1072 emit_label_after (labels
[unroll_number
- i
],
1073 PREV_INSN (loop_start
));
1075 memset ((char *) map
->insn_map
, 0, max_insnno
* sizeof (rtx
));
1076 memset ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1077 0, (VARRAY_SIZE (map
->const_equiv_varray
)
1078 * sizeof (struct const_equiv_data
)));
1081 for (j
= 0; j
< max_labelno
; j
++)
1083 set_label_in_map (map
, j
, gen_label_rtx ());
1085 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1089 = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1090 record_base_value (REGNO (map
->reg_map
[r
]),
1091 regno_reg_rtx
[r
], 0);
1093 /* The last copy needs the compare/branch insns at the end,
1094 so reset copy_end here if the loop ends with a conditional
1097 if (i
== unroll_number
- 1)
1099 if (GET_CODE (last_loop_insn
) == BARRIER
)
1100 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1102 copy_end
= last_loop_insn
;
1105 /* None of the copies are the `last_iteration', so just
1106 pass zero for that parameter. */
1107 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
, 0,
1108 unroll_type
, start_label
, loop_end
,
1109 loop_start
, copy_end
);
1111 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1113 if (GET_CODE (last_loop_insn
) == BARRIER
)
1115 insert_before
= PREV_INSN (last_loop_insn
);
1116 copy_end
= PREV_INSN (insert_before
);
1120 insert_before
= last_loop_insn
;
1122 /* The instruction immediately before the JUMP_INSN may
1123 be a compare instruction which we do not want to copy
1125 if (sets_cc0_p (PREV_INSN (insert_before
)))
1126 insert_before
= PREV_INSN (insert_before
);
1128 copy_end
= PREV_INSN (insert_before
);
1131 /* Set unroll type to MODULO now. */
1132 unroll_type
= UNROLL_MODULO
;
1133 loop_preconditioned
= 1;
1140 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1141 the loop unless all loops are being unrolled. */
1142 if (unroll_type
== UNROLL_NAIVE
&& ! flag_unroll_all_loops
)
1144 if (loop_dump_stream
)
1145 fprintf (loop_dump_stream
,
1146 "Unrolling failure: Naive unrolling not being done.\n");
1150 /* At this point, we are guaranteed to unroll the loop. */
1152 /* Keep track of the unroll factor for the loop. */
1153 loop_info
->unroll_number
= unroll_number
;
1155 /* For each biv and giv, determine whether it can be safely split into
1156 a different variable for each unrolled copy of the loop body.
1157 We precalculate and save this info here, since computing it is
1160 Do this before deleting any instructions from the loop, so that
1161 back_branch_in_range_p will work correctly. */
1163 if (splitting_not_safe
)
1166 temp
= find_splittable_regs (loop
, unroll_type
,
1167 end_insert_before
, unroll_number
);
1169 /* find_splittable_regs may have created some new registers, so must
1170 reallocate the reg_map with the new larger size, and must realloc
1171 the constant maps also. */
1173 maxregnum
= max_reg_num ();
1174 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
1176 init_reg_map (map
, maxregnum
);
1178 if (map
->const_equiv_varray
== 0)
1179 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1180 maxregnum
+ temp
* unroll_number
* 2,
1182 global_const_equiv_varray
= map
->const_equiv_varray
;
1184 /* Search the list of bivs and givs to find ones which need to be remapped
1185 when split, and set their reg_map entry appropriately. */
1187 for (bl
= ivs
->loop_iv_list
; bl
; bl
= bl
->next
)
1189 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1190 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1192 /* Currently, non-reduced/final-value givs are never split. */
1193 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1194 if (REGNO (v
->src_reg
) != bl
->regno
)
1195 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1199 /* Use our current register alignment and pointer flags. */
1200 map
->regno_pointer_flag
= cfun
->emit
->regno_pointer_flag
;
1201 map
->regno_pointer_align
= cfun
->emit
->regno_pointer_align
;
1203 /* If the loop is being partially unrolled, and the iteration variables
1204 are being split, and are being renamed for the split, then must fix up
1205 the compare/jump instruction at the end of the loop to refer to the new
1206 registers. This compare isn't copied, so the registers used in it
1207 will never be replaced if it isn't done here. */
1209 if (unroll_type
== UNROLL_MODULO
)
1211 insn
= NEXT_INSN (copy_end
);
1212 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1213 PATTERN (insn
) = remap_split_bivs (loop
, PATTERN (insn
));
1216 /* For unroll_number times, make a copy of each instruction
1217 between copy_start and copy_end, and insert these new instructions
1218 before the end of the loop. */
1220 for (i
= 0; i
< unroll_number
; i
++)
1222 memset ((char *) map
->insn_map
, 0, max_insnno
* sizeof (rtx
));
1223 memset ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0), 0,
1224 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1227 for (j
= 0; j
< max_labelno
; j
++)
1229 set_label_in_map (map
, j
, gen_label_rtx ());
1231 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1234 map
->reg_map
[r
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1235 record_base_value (REGNO (map
->reg_map
[r
]),
1236 regno_reg_rtx
[r
], 0);
1239 /* If loop starts with a branch to the test, then fix it so that
1240 it points to the test of the first unrolled copy of the loop. */
1241 if (i
== 0 && loop_start
!= copy_start
)
1243 insn
= PREV_INSN (copy_start
);
1244 pattern
= PATTERN (insn
);
1246 tem
= get_label_from_map (map
,
1248 (XEXP (SET_SRC (pattern
), 0)));
1249 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1251 /* Set the jump label so that it can be used by later loop unrolling
1253 JUMP_LABEL (insn
) = tem
;
1254 LABEL_NUSES (tem
)++;
1257 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
,
1258 i
== unroll_number
- 1, unroll_type
, start_label
,
1259 loop_end
, insert_before
, insert_before
);
1262 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1263 insn to be deleted. This prevents any runaway delete_insn call from
1264 more insns that it should, as it always stops at a CODE_LABEL. */
1266 /* Delete the compare and branch at the end of the loop if completely
1267 unrolling the loop. Deleting the backward branch at the end also
1268 deletes the code label at the start of the loop. This is done at
1269 the very end to avoid problems with back_branch_in_range_p. */
1271 if (unroll_type
== UNROLL_COMPLETELY
)
1272 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1274 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1276 /* Delete all of the original loop instructions. Don't delete the
1277 LOOP_BEG note, or the first code label in the loop. */
1279 insn
= NEXT_INSN (copy_start
);
1280 while (insn
!= safety_label
)
1282 /* ??? Don't delete named code labels. They will be deleted when the
1283 jump that references them is deleted. Otherwise, we end up deleting
1284 them twice, which causes them to completely disappear instead of turn
1285 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1286 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1287 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1288 associated LABEL_DECL to point to one of the new label instances. */
1289 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1290 if (insn
!= start_label
1291 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1292 && ! (GET_CODE (insn
) == NOTE
1293 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1294 insn
= delete_insn (insn
);
1296 insn
= NEXT_INSN (insn
);
1299 /* Can now delete the 'safety' label emitted to protect us from runaway
1300 delete_insn calls. */
1301 if (INSN_DELETED_P (safety_label
))
1303 delete_insn (safety_label
);
1305 /* If exit_label exists, emit it after the loop. Doing the emit here
1306 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1307 This is needed so that mostly_true_jump in reorg.c will treat jumps
1308 to this loop end label correctly, i.e. predict that they are usually
1311 emit_label_after (exit_label
, loop_end
);
1314 if (unroll_type
== UNROLL_COMPLETELY
)
1316 /* Remove the loop notes since this is no longer a loop. */
1318 delete_insn (loop
->vtop
);
1320 delete_insn (loop
->cont
);
1322 delete_insn (loop_start
);
1324 delete_insn (loop_end
);
1327 if (map
->const_equiv_varray
)
1328 VARRAY_FREE (map
->const_equiv_varray
);
1331 free (map
->label_map
);
1334 free (map
->insn_map
);
1335 free (splittable_regs
);
1336 free (splittable_regs_updates
);
1337 free (addr_combined_regs
);
1340 free (map
->reg_map
);
1344 /* Return true if the loop can be safely, and profitably, preconditioned
1345 so that the unrolled copies of the loop body don't need exit tests.
1347 This only works if final_value, initial_value and increment can be
1348 determined, and if increment is a constant power of 2.
1349 If increment is not a power of 2, then the preconditioning modulo
1350 operation would require a real modulo instead of a boolean AND, and this
1351 is not considered `profitable'. */
1353 /* ??? If the loop is known to be executed very many times, or the machine
1354 has a very cheap divide instruction, then preconditioning is a win even
1355 when the increment is not a power of 2. Use RTX_COST to compute
1356 whether divide is cheap.
1357 ??? A divide by constant doesn't actually need a divide, look at
1358 expand_divmod. The reduced cost of this optimized modulo is not
1359 reflected in RTX_COST. */
1362 precondition_loop_p (loop
, initial_value
, final_value
, increment
, mode
)
1363 const struct loop
*loop
;
1364 rtx
*initial_value
, *final_value
, *increment
;
1365 enum machine_mode
*mode
;
1367 rtx loop_start
= loop
->start
;
1368 struct loop_info
*loop_info
= LOOP_INFO (loop
);
1370 if (loop_info
->n_iterations
> 0)
1372 *initial_value
= const0_rtx
;
1373 *increment
= const1_rtx
;
1374 *final_value
= GEN_INT (loop_info
->n_iterations
);
1377 if (loop_dump_stream
)
1379 fputs ("Preconditioning: Success, number of iterations known, ",
1381 fprintf (loop_dump_stream
, HOST_WIDE_INT_PRINT_DEC
,
1382 loop_info
->n_iterations
);
1383 fputs (".\n", loop_dump_stream
);
1388 if (loop_info
->initial_value
== 0)
1390 if (loop_dump_stream
)
1391 fprintf (loop_dump_stream
,
1392 "Preconditioning: Could not find initial value.\n");
1395 else if (loop_info
->increment
== 0)
1397 if (loop_dump_stream
)
1398 fprintf (loop_dump_stream
,
1399 "Preconditioning: Could not find increment value.\n");
1402 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1404 if (loop_dump_stream
)
1405 fprintf (loop_dump_stream
,
1406 "Preconditioning: Increment not a constant.\n");
1409 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1410 && (exact_log2 (-INTVAL (loop_info
->increment
)) < 0))
1412 if (loop_dump_stream
)
1413 fprintf (loop_dump_stream
,
1414 "Preconditioning: Increment not a constant power of 2.\n");
1418 /* Unsigned_compare and compare_dir can be ignored here, since they do
1419 not matter for preconditioning. */
1421 if (loop_info
->final_value
== 0)
1423 if (loop_dump_stream
)
1424 fprintf (loop_dump_stream
,
1425 "Preconditioning: EQ comparison loop.\n");
1429 /* Must ensure that final_value is invariant, so call
1430 loop_invariant_p to check. Before doing so, must check regno
1431 against max_reg_before_loop to make sure that the register is in
1432 the range covered by loop_invariant_p. If it isn't, then it is
1433 most likely a biv/giv which by definition are not invariant. */
1434 if ((GET_CODE (loop_info
->final_value
) == REG
1435 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1436 || (GET_CODE (loop_info
->final_value
) == PLUS
1437 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1438 || ! loop_invariant_p (loop
, loop_info
->final_value
))
1440 if (loop_dump_stream
)
1441 fprintf (loop_dump_stream
,
1442 "Preconditioning: Final value not invariant.\n");
1446 /* Fail for floating point values, since the caller of this function
1447 does not have code to deal with them. */
1448 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1449 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1451 if (loop_dump_stream
)
1452 fprintf (loop_dump_stream
,
1453 "Preconditioning: Floating point final or initial value.\n");
1457 /* Fail if loop_info->iteration_var is not live before loop_start,
1458 since we need to test its value in the preconditioning code. */
1460 if (uid_luid
[REGNO_FIRST_UID (REGNO (loop_info
->iteration_var
))]
1461 > INSN_LUID (loop_start
))
1463 if (loop_dump_stream
)
1464 fprintf (loop_dump_stream
,
1465 "Preconditioning: Iteration var not live before loop start.\n");
1469 /* Note that loop_iterations biases the initial value for GIV iterators
1470 such as "while (i-- > 0)" so that we can calculate the number of
1471 iterations just like for BIV iterators.
1473 Also note that the absolute values of initial_value and
1474 final_value are unimportant as only their difference is used for
1475 calculating the number of loop iterations. */
1476 *initial_value
= loop_info
->initial_value
;
1477 *increment
= loop_info
->increment
;
1478 *final_value
= loop_info
->final_value
;
1480 /* Decide what mode to do these calculations in. Choose the larger
1481 of final_value's mode and initial_value's mode, or a full-word if
1482 both are constants. */
1483 *mode
= GET_MODE (*final_value
);
1484 if (*mode
== VOIDmode
)
1486 *mode
= GET_MODE (*initial_value
);
1487 if (*mode
== VOIDmode
)
1490 else if (*mode
!= GET_MODE (*initial_value
)
1491 && (GET_MODE_SIZE (*mode
)
1492 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1493 *mode
= GET_MODE (*initial_value
);
1496 if (loop_dump_stream
)
1497 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1501 /* All pseudo-registers must be mapped to themselves. Two hard registers
1502 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1503 REGNUM, to avoid function-inlining specific conversions of these
1504 registers. All other hard regs can not be mapped because they may be
1509 init_reg_map (map
, maxregnum
)
1510 struct inline_remap
*map
;
1515 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1516 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1517 /* Just clear the rest of the entries. */
1518 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1519 map
->reg_map
[i
] = 0;
1521 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1522 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1523 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1524 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1527 /* Strength-reduction will often emit code for optimized biv/givs which
1528 calculates their value in a temporary register, and then copies the result
1529 to the iv. This procedure reconstructs the pattern computing the iv;
1530 verifying that all operands are of the proper form.
1532 PATTERN must be the result of single_set.
1533 The return value is the amount that the giv is incremented by. */
1536 calculate_giv_inc (pattern
, src_insn
, regno
)
1537 rtx pattern
, src_insn
;
1541 rtx increment_total
= 0;
1545 /* Verify that we have an increment insn here. First check for a plus
1546 as the set source. */
1547 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1549 /* SR sometimes computes the new giv value in a temp, then copies it
1551 src_insn
= PREV_INSN (src_insn
);
1552 pattern
= PATTERN (src_insn
);
1553 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1556 /* The last insn emitted is not needed, so delete it to avoid confusing
1557 the second cse pass. This insn sets the giv unnecessarily. */
1558 delete_insn (get_last_insn ());
1561 /* Verify that we have a constant as the second operand of the plus. */
1562 increment
= XEXP (SET_SRC (pattern
), 1);
1563 if (GET_CODE (increment
) != CONST_INT
)
1565 /* SR sometimes puts the constant in a register, especially if it is
1566 too big to be an add immed operand. */
1567 src_insn
= PREV_INSN (src_insn
);
1568 increment
= SET_SRC (PATTERN (src_insn
));
1570 /* SR may have used LO_SUM to compute the constant if it is too large
1571 for a load immed operand. In this case, the constant is in operand
1572 one of the LO_SUM rtx. */
1573 if (GET_CODE (increment
) == LO_SUM
)
1574 increment
= XEXP (increment
, 1);
1576 /* Some ports store large constants in memory and add a REG_EQUAL
1577 note to the store insn. */
1578 else if (GET_CODE (increment
) == MEM
)
1580 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1582 increment
= XEXP (note
, 0);
1585 else if (GET_CODE (increment
) == IOR
1586 || GET_CODE (increment
) == ASHIFT
1587 || GET_CODE (increment
) == PLUS
)
1589 /* The rs6000 port loads some constants with IOR.
1590 The alpha port loads some constants with ASHIFT and PLUS. */
1591 rtx second_part
= XEXP (increment
, 1);
1592 enum rtx_code code
= GET_CODE (increment
);
1594 src_insn
= PREV_INSN (src_insn
);
1595 increment
= SET_SRC (PATTERN (src_insn
));
1596 /* Don't need the last insn anymore. */
1597 delete_insn (get_last_insn ());
1599 if (GET_CODE (second_part
) != CONST_INT
1600 || GET_CODE (increment
) != CONST_INT
)
1604 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1605 else if (code
== PLUS
)
1606 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1608 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1611 if (GET_CODE (increment
) != CONST_INT
)
1614 /* The insn loading the constant into a register is no longer needed,
1616 delete_insn (get_last_insn ());
1619 if (increment_total
)
1620 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1622 increment_total
= increment
;
1624 /* Check that the source register is the same as the register we expected
1625 to see as the source. If not, something is seriously wrong. */
1626 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1627 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1629 /* Some machines (e.g. the romp), may emit two add instructions for
1630 certain constants, so lets try looking for another add immediately
1631 before this one if we have only seen one add insn so far. */
1637 src_insn
= PREV_INSN (src_insn
);
1638 pattern
= PATTERN (src_insn
);
1640 delete_insn (get_last_insn ());
1648 return increment_total
;
1651 /* Copy REG_NOTES, except for insn references, because not all insn_map
1652 entries are valid yet. We do need to copy registers now though, because
1653 the reg_map entries can change during copying. */
1656 initial_reg_note_copy (notes
, map
)
1658 struct inline_remap
*map
;
1665 copy
= rtx_alloc (GET_CODE (notes
));
1666 PUT_MODE (copy
, GET_MODE (notes
));
1668 if (GET_CODE (notes
) == EXPR_LIST
)
1669 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
, 0);
1670 else if (GET_CODE (notes
) == INSN_LIST
)
1671 /* Don't substitute for these yet. */
1672 XEXP (copy
, 0) = XEXP (notes
, 0);
1676 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1681 /* Fixup insn references in copied REG_NOTES. */
1684 final_reg_note_copy (notes
, map
)
1686 struct inline_remap
*map
;
1690 for (note
= notes
; note
; note
= XEXP (note
, 1))
1691 if (GET_CODE (note
) == INSN_LIST
)
1692 XEXP (note
, 0) = map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1695 /* Copy each instruction in the loop, substituting from map as appropriate.
1696 This is very similar to a loop in expand_inline_function. */
1699 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1700 unroll_type
, start_label
, loop_end
, insert_before
,
1703 rtx copy_start
, copy_end
;
1704 struct inline_remap
*map
;
1707 enum unroll_types unroll_type
;
1708 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1710 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
1712 rtx set
, tem
, copy
= NULL_RTX
;
1713 int dest_reg_was_split
, i
;
1717 rtx final_label
= 0;
1718 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1720 /* If this isn't the last iteration, then map any references to the
1721 start_label to final_label. Final label will then be emitted immediately
1722 after the end of this loop body if it was ever used.
1724 If this is the last iteration, then map references to the start_label
1726 if (! last_iteration
)
1728 final_label
= gen_label_rtx ();
1729 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), final_label
);
1732 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1736 /* Emit a NOTE_INSN_DELETED to force at least two insns onto the sequence.
1737 Else gen_sequence could return a raw pattern for a jump which we pass
1738 off to emit_insn_before (instead of emit_jump_insn_before) which causes
1739 a variety of losing behaviors later. */
1740 emit_note (0, NOTE_INSN_DELETED
);
1745 insn
= NEXT_INSN (insn
);
1747 map
->orig_asm_operands_vector
= 0;
1749 switch (GET_CODE (insn
))
1752 pattern
= PATTERN (insn
);
1756 /* Check to see if this is a giv that has been combined with
1757 some split address givs. (Combined in the sense that
1758 `combine_givs' in loop.c has put two givs in the same register.)
1759 In this case, we must search all givs based on the same biv to
1760 find the address givs. Then split the address givs.
1761 Do this before splitting the giv, since that may map the
1762 SET_DEST to a new register. */
1764 if ((set
= single_set (insn
))
1765 && GET_CODE (SET_DEST (set
)) == REG
1766 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1768 struct iv_class
*bl
;
1769 struct induction
*v
, *tv
;
1770 unsigned int regno
= REGNO (SET_DEST (set
));
1772 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1773 bl
= ivs
->reg_biv_class
[REGNO (v
->src_reg
)];
1775 /* Although the giv_inc amount is not needed here, we must call
1776 calculate_giv_inc here since it might try to delete the
1777 last insn emitted. If we wait until later to call it,
1778 we might accidentally delete insns generated immediately
1779 below by emit_unrolled_add. */
1781 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1783 /* Now find all address giv's that were combined with this
1785 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1786 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1790 /* If this DEST_ADDR giv was not split, then ignore it. */
1791 if (*tv
->location
!= tv
->dest_reg
)
1794 /* Scale this_giv_inc if the multiplicative factors of
1795 the two givs are different. */
1796 this_giv_inc
= INTVAL (giv_inc
);
1797 if (tv
->mult_val
!= v
->mult_val
)
1798 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1799 * INTVAL (tv
->mult_val
));
1801 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1802 *tv
->location
= tv
->dest_reg
;
1804 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1806 /* Must emit an insn to increment the split address
1807 giv. Add in the const_adjust field in case there
1808 was a constant eliminated from the address. */
1809 rtx value
, dest_reg
;
1811 /* tv->dest_reg will be either a bare register,
1812 or else a register plus a constant. */
1813 if (GET_CODE (tv
->dest_reg
) == REG
)
1814 dest_reg
= tv
->dest_reg
;
1816 dest_reg
= XEXP (tv
->dest_reg
, 0);
1818 /* Check for shared address givs, and avoid
1819 incrementing the shared pseudo reg more than
1821 if (! tv
->same_insn
&& ! tv
->shared
)
1823 /* tv->dest_reg may actually be a (PLUS (REG)
1824 (CONST)) here, so we must call plus_constant
1825 to add the const_adjust amount before calling
1826 emit_unrolled_add below. */
1827 value
= plus_constant (tv
->dest_reg
,
1830 if (GET_CODE (value
) == PLUS
)
1832 /* The constant could be too large for an add
1833 immediate, so can't directly emit an insn
1835 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1840 /* Reset the giv to be just the register again, in case
1841 it is used after the set we have just emitted.
1842 We must subtract the const_adjust factor added in
1844 tv
->dest_reg
= plus_constant (dest_reg
,
1846 *tv
->location
= tv
->dest_reg
;
1851 /* If this is a setting of a splittable variable, then determine
1852 how to split the variable, create a new set based on this split,
1853 and set up the reg_map so that later uses of the variable will
1854 use the new split variable. */
1856 dest_reg_was_split
= 0;
1858 if ((set
= single_set (insn
))
1859 && GET_CODE (SET_DEST (set
)) == REG
1860 && splittable_regs
[REGNO (SET_DEST (set
))])
1862 unsigned int regno
= REGNO (SET_DEST (set
));
1863 unsigned int src_regno
;
1865 dest_reg_was_split
= 1;
1867 giv_dest_reg
= SET_DEST (set
);
1868 giv_src_reg
= giv_dest_reg
;
1869 /* Compute the increment value for the giv, if it wasn't
1870 already computed above. */
1872 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1874 src_regno
= REGNO (giv_src_reg
);
1876 if (unroll_type
== UNROLL_COMPLETELY
)
1878 /* Completely unrolling the loop. Set the induction
1879 variable to a known constant value. */
1881 /* The value in splittable_regs may be an invariant
1882 value, so we must use plus_constant here. */
1883 splittable_regs
[regno
]
1884 = plus_constant (splittable_regs
[src_regno
],
1887 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1889 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1890 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1894 /* The splittable_regs value must be a REG or a
1895 CONST_INT, so put the entire value in the giv_src_reg
1897 giv_src_reg
= splittable_regs
[regno
];
1898 giv_inc
= const0_rtx
;
1903 /* Partially unrolling loop. Create a new pseudo
1904 register for the iteration variable, and set it to
1905 be a constant plus the original register. Except
1906 on the last iteration, when the result has to
1907 go back into the original iteration var register. */
1909 /* Handle bivs which must be mapped to a new register
1910 when split. This happens for bivs which need their
1911 final value set before loop entry. The new register
1912 for the biv was stored in the biv's first struct
1913 induction entry by find_splittable_regs. */
1915 if (regno
< max_reg_before_loop
1916 && REG_IV_TYPE (ivs
, regno
) == BASIC_INDUCT
)
1918 giv_src_reg
= ivs
->reg_biv_class
[regno
]->biv
->src_reg
;
1919 giv_dest_reg
= giv_src_reg
;
1923 /* If non-reduced/final-value givs were split, then
1924 this would have to remap those givs also. See
1925 find_splittable_regs. */
1928 splittable_regs
[regno
]
1929 = simplify_gen_binary (PLUS
, GET_MODE (giv_src_reg
),
1931 splittable_regs
[src_regno
]);
1932 giv_inc
= splittable_regs
[regno
];
1934 /* Now split the induction variable by changing the dest
1935 of this insn to a new register, and setting its
1936 reg_map entry to point to this new register.
1938 If this is the last iteration, and this is the last insn
1939 that will update the iv, then reuse the original dest,
1940 to ensure that the iv will have the proper value when
1941 the loop exits or repeats.
1943 Using splittable_regs_updates here like this is safe,
1944 because it can only be greater than one if all
1945 instructions modifying the iv are always executed in
1948 if (! last_iteration
1949 || (splittable_regs_updates
[regno
]-- != 1))
1951 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
1953 map
->reg_map
[regno
] = tem
;
1954 record_base_value (REGNO (tem
),
1955 giv_inc
== const0_rtx
1957 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
1958 giv_src_reg
, giv_inc
),
1962 map
->reg_map
[regno
] = giv_src_reg
;
1965 /* The constant being added could be too large for an add
1966 immediate, so can't directly emit an insn here. */
1967 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
1968 copy
= get_last_insn ();
1969 pattern
= PATTERN (copy
);
1973 pattern
= copy_rtx_and_substitute (pattern
, map
, 0);
1974 copy
= emit_insn (pattern
);
1976 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1979 /* If this insn is setting CC0, it may need to look at
1980 the insn that uses CC0 to see what type of insn it is.
1981 In that case, the call to recog via validate_change will
1982 fail. So don't substitute constants here. Instead,
1983 do it when we emit the following insn.
1985 For example, see the pyr.md file. That machine has signed and
1986 unsigned compares. The compare patterns must check the
1987 following branch insn to see which what kind of compare to
1990 If the previous insn set CC0, substitute constants on it as
1992 if (sets_cc0_p (PATTERN (copy
)) != 0)
1997 try_constants (cc0_insn
, map
);
1999 try_constants (copy
, map
);
2002 try_constants (copy
, map
);
2005 /* Make split induction variable constants `permanent' since we
2006 know there are no backward branches across iteration variable
2007 settings which would invalidate this. */
2008 if (dest_reg_was_split
)
2010 int regno
= REGNO (SET_DEST (set
));
2012 if ((size_t) regno
< VARRAY_SIZE (map
->const_equiv_varray
)
2013 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
2015 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
2020 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2021 copy
= emit_jump_insn (pattern
);
2022 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2024 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
2025 && ! last_iteration
)
2027 /* Update JUMP_LABEL make invert_jump work correctly. */
2028 JUMP_LABEL (copy
) = get_label_from_map (map
,
2030 (JUMP_LABEL (insn
)));
2031 LABEL_NUSES (JUMP_LABEL (copy
))++;
2033 /* This is a branch to the beginning of the loop; this is the
2034 last insn being copied; and this is not the last iteration.
2035 In this case, we want to change the original fall through
2036 case to be a branch past the end of the loop, and the
2037 original jump label case to fall_through. */
2039 if (!invert_jump (copy
, exit_label
, 0))
2042 rtx lab
= gen_label_rtx ();
2043 /* Can't do it by reversing the jump (probably because we
2044 couldn't reverse the conditions), so emit a new
2045 jump_insn after COPY, and redirect the jump around
2047 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2048 jmp
= emit_barrier_after (jmp
);
2049 emit_label_after (lab
, jmp
);
2050 LABEL_NUSES (lab
) = 0;
2051 if (!redirect_jump (copy
, lab
, 0))
2058 try_constants (cc0_insn
, map
);
2061 try_constants (copy
, map
);
2063 /* Set the jump label of COPY correctly to avoid problems with
2064 later passes of unroll_loop, if INSN had jump label set. */
2065 if (JUMP_LABEL (insn
))
2069 /* Can't use the label_map for every insn, since this may be
2070 the backward branch, and hence the label was not mapped. */
2071 if ((set
= single_set (copy
)))
2073 tem
= SET_SRC (set
);
2074 if (GET_CODE (tem
) == LABEL_REF
)
2075 label
= XEXP (tem
, 0);
2076 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2078 if (XEXP (tem
, 1) != pc_rtx
)
2079 label
= XEXP (XEXP (tem
, 1), 0);
2081 label
= XEXP (XEXP (tem
, 2), 0);
2085 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2086 JUMP_LABEL (copy
) = label
;
2089 /* An unrecognizable jump insn, probably the entry jump
2090 for a switch statement. This label must have been mapped,
2091 so just use the label_map to get the new jump label. */
2093 = get_label_from_map (map
,
2094 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2097 /* If this is a non-local jump, then must increase the label
2098 use count so that the label will not be deleted when the
2099 original jump is deleted. */
2100 LABEL_NUSES (JUMP_LABEL (copy
))++;
2102 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2103 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2105 rtx pat
= PATTERN (copy
);
2106 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2107 int len
= XVECLEN (pat
, diff_vec_p
);
2110 for (i
= 0; i
< len
; i
++)
2111 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2114 /* If this used to be a conditional jump insn but whose branch
2115 direction is now known, we must do something special. */
2116 if (any_condjump_p (insn
) && onlyjump_p (insn
) && map
->last_pc_value
)
2119 /* If the previous insn set cc0 for us, delete it. */
2120 if (sets_cc0_p (PREV_INSN (copy
)))
2121 delete_insn (PREV_INSN (copy
));
2124 /* If this is now a no-op, delete it. */
2125 if (map
->last_pc_value
== pc_rtx
)
2127 /* Don't let delete_insn delete the label referenced here,
2128 because we might possibly need it later for some other
2129 instruction in the loop. */
2130 if (JUMP_LABEL (copy
))
2131 LABEL_NUSES (JUMP_LABEL (copy
))++;
2133 if (JUMP_LABEL (copy
))
2134 LABEL_NUSES (JUMP_LABEL (copy
))--;
2138 /* Otherwise, this is unconditional jump so we must put a
2139 BARRIER after it. We could do some dead code elimination
2140 here, but jump.c will do it just as well. */
2146 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2147 copy
= emit_call_insn (pattern
);
2148 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2150 /* Because the USAGE information potentially contains objects other
2151 than hard registers, we need to copy it. */
2152 CALL_INSN_FUNCTION_USAGE (copy
)
2153 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
),
2158 try_constants (cc0_insn
, map
);
2161 try_constants (copy
, map
);
2163 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2164 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2165 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2169 /* If this is the loop start label, then we don't need to emit a
2170 copy of this label since no one will use it. */
2172 if (insn
!= start_label
)
2174 copy
= emit_label (get_label_from_map (map
,
2175 CODE_LABEL_NUMBER (insn
)));
2181 copy
= emit_barrier ();
2185 /* VTOP and CONT notes are valid only before the loop exit test.
2186 If placed anywhere else, loop may generate bad code. */
2187 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2188 the associated rtl. We do not want to share the structure in
2191 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2192 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED_LABEL
2193 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2194 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2195 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2196 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2197 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2198 NOTE_LINE_NUMBER (insn
));
2207 map
->insn_map
[INSN_UID (insn
)] = copy
;
2209 while (insn
!= copy_end
);
2211 /* Now finish coping the REG_NOTES. */
2215 insn
= NEXT_INSN (insn
);
2216 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2217 || GET_CODE (insn
) == CALL_INSN
)
2218 && map
->insn_map
[INSN_UID (insn
)])
2219 final_reg_note_copy (REG_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2221 while (insn
!= copy_end
);
2223 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2224 each of these notes here, since there may be some important ones, such as
2225 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2226 iteration, because the original notes won't be deleted.
2228 We can't use insert_before here, because when from preconditioning,
2229 insert_before points before the loop. We can't use copy_end, because
2230 there may be insns already inserted after it (which we don't want to
2231 copy) when not from preconditioning code. */
2233 if (! last_iteration
)
2235 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2237 /* VTOP notes are valid only before the loop exit test.
2238 If placed anywhere else, loop may generate bad code.
2239 There is no need to test for NOTE_INSN_LOOP_CONT notes
2240 here, since COPY_NOTES_FROM will be at most one or two (for cc0)
2241 instructions before the last insn in the loop, and if the
2242 end test is that short, there will be a VTOP note between
2243 the CONT note and the test. */
2244 if (GET_CODE (insn
) == NOTE
2245 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2246 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2247 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
)
2248 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2252 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2253 emit_label (final_label
);
2255 tem
= gen_sequence ();
2257 emit_insn_before (tem
, insert_before
);
2260 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2261 emitted. This will correctly handle the case where the increment value
2262 won't fit in the immediate field of a PLUS insns. */
2265 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2266 rtx dest_reg
, src_reg
, increment
;
2270 result
= expand_binop (GET_MODE (dest_reg
), add_optab
, src_reg
, increment
,
2271 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2273 if (dest_reg
!= result
)
2274 emit_move_insn (dest_reg
, result
);
2277 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2278 is a backward branch in that range that branches to somewhere between
2279 LOOP->START and INSN. Returns 0 otherwise. */
2281 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2282 In practice, this is not a problem, because this function is seldom called,
2283 and uses a negligible amount of CPU time on average. */
2286 back_branch_in_range_p (loop
, insn
)
2287 const struct loop
*loop
;
2290 rtx p
, q
, target_insn
;
2291 rtx loop_start
= loop
->start
;
2292 rtx loop_end
= loop
->end
;
2293 rtx orig_loop_end
= loop
->end
;
2295 /* Stop before we get to the backward branch at the end of the loop. */
2296 loop_end
= prev_nonnote_insn (loop_end
);
2297 if (GET_CODE (loop_end
) == BARRIER
)
2298 loop_end
= PREV_INSN (loop_end
);
2300 /* Check in case insn has been deleted, search forward for first non
2301 deleted insn following it. */
2302 while (INSN_DELETED_P (insn
))
2303 insn
= NEXT_INSN (insn
);
2305 /* Check for the case where insn is the last insn in the loop. Deal
2306 with the case where INSN was a deleted loop test insn, in which case
2307 it will now be the NOTE_LOOP_END. */
2308 if (insn
== loop_end
|| insn
== orig_loop_end
)
2311 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2313 if (GET_CODE (p
) == JUMP_INSN
)
2315 target_insn
= JUMP_LABEL (p
);
2317 /* Search from loop_start to insn, to see if one of them is
2318 the target_insn. We can't use INSN_LUID comparisons here,
2319 since insn may not have an LUID entry. */
2320 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2321 if (q
== target_insn
)
2329 /* Try to generate the simplest rtx for the expression
2330 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2334 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2335 rtx mult1
, mult2
, add1
;
2336 enum machine_mode mode
;
2341 /* The modes must all be the same. This should always be true. For now,
2342 check to make sure. */
2343 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2344 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2345 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2348 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2349 will be a constant. */
2350 if (GET_CODE (mult1
) == CONST_INT
)
2357 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2359 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2361 /* Again, put the constant second. */
2362 if (GET_CODE (add1
) == CONST_INT
)
2369 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2371 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2376 /* Searches the list of induction struct's for the biv BL, to try to calculate
2377 the total increment value for one iteration of the loop as a constant.
2379 Returns the increment value as an rtx, simplified as much as possible,
2380 if it can be calculated. Otherwise, returns 0. */
2383 biv_total_increment (bl
)
2384 struct iv_class
*bl
;
2386 struct induction
*v
;
2389 /* For increment, must check every instruction that sets it. Each
2390 instruction must be executed only once each time through the loop.
2391 To verify this, we check that the insn is always executed, and that
2392 there are no backward branches after the insn that branch to before it.
2393 Also, the insn must have a mult_val of one (to make sure it really is
2396 result
= const0_rtx
;
2397 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2399 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2400 && ! v
->maybe_multiple
)
2401 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2409 /* For each biv and giv, determine whether it can be safely split into
2410 a different variable for each unrolled copy of the loop body. If it
2411 is safe to split, then indicate that by saving some useful info
2412 in the splittable_regs array.
2414 If the loop is being completely unrolled, then splittable_regs will hold
2415 the current value of the induction variable while the loop is unrolled.
2416 It must be set to the initial value of the induction variable here.
2417 Otherwise, splittable_regs will hold the difference between the current
2418 value of the induction variable and the value the induction variable had
2419 at the top of the loop. It must be set to the value 0 here.
2421 Returns the total number of instructions that set registers that are
2424 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2425 constant values are unnecessary, since we can easily calculate increment
2426 values in this case even if nothing is constant. The increment value
2427 should not involve a multiply however. */
2429 /* ?? Even if the biv/giv increment values aren't constant, it may still
2430 be beneficial to split the variable if the loop is only unrolled a few
2431 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2434 find_splittable_regs (loop
, unroll_type
, end_insert_before
, unroll_number
)
2435 const struct loop
*loop
;
2436 enum unroll_types unroll_type
;
2437 rtx end_insert_before
;
2440 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
2441 struct iv_class
*bl
;
2442 struct induction
*v
;
2444 rtx biv_final_value
;
2447 rtx loop_start
= loop
->start
;
2448 rtx loop_end
= loop
->end
;
2450 for (bl
= ivs
->loop_iv_list
; bl
; bl
= bl
->next
)
2452 /* Biv_total_increment must return a constant value,
2453 otherwise we can not calculate the split values. */
2455 increment
= biv_total_increment (bl
);
2456 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2459 /* The loop must be unrolled completely, or else have a known number
2460 of iterations and only one exit, or else the biv must be dead
2461 outside the loop, or else the final value must be known. Otherwise,
2462 it is unsafe to split the biv since it may not have the proper
2463 value on loop exit. */
2465 /* loop_number_exit_count is non-zero if the loop has an exit other than
2466 a fall through at the end. */
2469 biv_final_value
= 0;
2470 if (unroll_type
!= UNROLL_COMPLETELY
2471 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2472 && (uid_luid
[REGNO_LAST_UID (bl
->regno
)] >= INSN_LUID (loop_end
)
2474 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2475 || (uid_luid
[REGNO_FIRST_UID (bl
->regno
)]
2476 < INSN_LUID (bl
->init_insn
))
2477 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2478 && ! (biv_final_value
= final_biv_value (loop
, bl
)))
2481 /* If any of the insns setting the BIV don't do so with a simple
2482 PLUS, we don't know how to split it. */
2483 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2484 if ((tem
= single_set (v
->insn
)) == 0
2485 || GET_CODE (SET_DEST (tem
)) != REG
2486 || REGNO (SET_DEST (tem
)) != bl
->regno
2487 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2490 /* If final value is non-zero, then must emit an instruction which sets
2491 the value of the biv to the proper value. This is done after
2492 handling all of the givs, since some of them may need to use the
2493 biv's value in their initialization code. */
2495 /* This biv is splittable. If completely unrolling the loop, save
2496 the biv's initial value. Otherwise, save the constant zero. */
2498 if (biv_splittable
== 1)
2500 if (unroll_type
== UNROLL_COMPLETELY
)
2502 /* If the initial value of the biv is itself (i.e. it is too
2503 complicated for strength_reduce to compute), or is a hard
2504 register, or it isn't invariant, then we must create a new
2505 pseudo reg to hold the initial value of the biv. */
2507 if (GET_CODE (bl
->initial_value
) == REG
2508 && (REGNO (bl
->initial_value
) == bl
->regno
2509 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2510 || ! loop_invariant_p (loop
, bl
->initial_value
)))
2512 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2514 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2515 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2518 if (loop_dump_stream
)
2519 fprintf (loop_dump_stream
,
2520 "Biv %d initial value remapped to %d.\n",
2521 bl
->regno
, REGNO (tem
));
2523 splittable_regs
[bl
->regno
] = tem
;
2526 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2529 splittable_regs
[bl
->regno
] = const0_rtx
;
2531 /* Save the number of instructions that modify the biv, so that
2532 we can treat the last one specially. */
2534 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2535 result
+= bl
->biv_count
;
2537 if (loop_dump_stream
)
2538 fprintf (loop_dump_stream
,
2539 "Biv %d safe to split.\n", bl
->regno
);
2542 /* Check every giv that depends on this biv to see whether it is
2543 splittable also. Even if the biv isn't splittable, givs which
2544 depend on it may be splittable if the biv is live outside the
2545 loop, and the givs aren't. */
2547 result
+= find_splittable_givs (loop
, bl
, unroll_type
, increment
,
2550 /* If final value is non-zero, then must emit an instruction which sets
2551 the value of the biv to the proper value. This is done after
2552 handling all of the givs, since some of them may need to use the
2553 biv's value in their initialization code. */
2554 if (biv_final_value
)
2556 /* If the loop has multiple exits, emit the insns before the
2557 loop to ensure that it will always be executed no matter
2558 how the loop exits. Otherwise emit the insn after the loop,
2559 since this is slightly more efficient. */
2560 if (! loop
->exit_count
)
2561 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2566 /* Create a new register to hold the value of the biv, and then
2567 set the biv to its final value before the loop start. The biv
2568 is set to its final value before loop start to ensure that
2569 this insn will always be executed, no matter how the loop
2571 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2572 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2574 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2576 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2580 if (loop_dump_stream
)
2581 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2582 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2584 /* Set up the mapping from the original biv register to the new
2586 bl
->biv
->src_reg
= tem
;
2593 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2594 for the instruction that is using it. Do not make any changes to that
2598 verify_addresses (v
, giv_inc
, unroll_number
)
2599 struct induction
*v
;
2604 rtx orig_addr
= *v
->location
;
2605 rtx last_addr
= plus_constant (v
->dest_reg
,
2606 INTVAL (giv_inc
) * (unroll_number
- 1));
2608 /* First check to see if either address would fail. Handle the fact
2609 that we have may have a match_dup. */
2610 if (! validate_replace_rtx (*v
->location
, v
->dest_reg
, v
->insn
)
2611 || ! validate_replace_rtx (*v
->location
, last_addr
, v
->insn
))
2614 /* Now put things back the way they were before. This should always
2616 if (! validate_replace_rtx (*v
->location
, orig_addr
, v
->insn
))
2622 /* For every giv based on the biv BL, check to determine whether it is
2623 splittable. This is a subroutine to find_splittable_regs ().
2625 Return the number of instructions that set splittable registers. */
2628 find_splittable_givs (loop
, bl
, unroll_type
, increment
, unroll_number
)
2629 const struct loop
*loop
;
2630 struct iv_class
*bl
;
2631 enum unroll_types unroll_type
;
2635 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
2636 struct induction
*v
, *v2
;
2641 /* Scan the list of givs, and set the same_insn field when there are
2642 multiple identical givs in the same insn. */
2643 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2644 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2645 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2649 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2653 /* Only split the giv if it has already been reduced, or if the loop is
2654 being completely unrolled. */
2655 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2658 /* The giv can be split if the insn that sets the giv is executed once
2659 and only once on every iteration of the loop. */
2660 /* An address giv can always be split. v->insn is just a use not a set,
2661 and hence it does not matter whether it is always executed. All that
2662 matters is that all the biv increments are always executed, and we
2663 won't reach here if they aren't. */
2664 if (v
->giv_type
!= DEST_ADDR
2665 && (! v
->always_computable
2666 || back_branch_in_range_p (loop
, v
->insn
)))
2669 /* The giv increment value must be a constant. */
2670 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2672 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2675 /* The loop must be unrolled completely, or else have a known number of
2676 iterations and only one exit, or else the giv must be dead outside
2677 the loop, or else the final value of the giv must be known.
2678 Otherwise, it is not safe to split the giv since it may not have the
2679 proper value on loop exit. */
2681 /* The used outside loop test will fail for DEST_ADDR givs. They are
2682 never used outside the loop anyways, so it is always safe to split a
2686 if (unroll_type
!= UNROLL_COMPLETELY
2687 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2688 && v
->giv_type
!= DEST_ADDR
2689 /* The next part is true if the pseudo is used outside the loop.
2690 We assume that this is true for any pseudo created after loop
2691 starts, because we don't have a reg_n_info entry for them. */
2692 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2693 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2694 /* Check for the case where the pseudo is set by a shift/add
2695 sequence, in which case the first insn setting the pseudo
2696 is the first insn of the shift/add sequence. */
2697 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2698 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2699 != INSN_UID (XEXP (tem
, 0)))))
2700 /* Line above always fails if INSN was moved by loop opt. */
2701 || (uid_luid
[REGNO_LAST_UID (REGNO (v
->dest_reg
))]
2702 >= INSN_LUID (loop
->end
)))
2703 && ! (final_value
= v
->final_value
))
2707 /* Currently, non-reduced/final-value givs are never split. */
2708 /* Should emit insns after the loop if possible, as the biv final value
2711 /* If the final value is non-zero, and the giv has not been reduced,
2712 then must emit an instruction to set the final value. */
2713 if (final_value
&& !v
->new_reg
)
2715 /* Create a new register to hold the value of the giv, and then set
2716 the giv to its final value before the loop start. The giv is set
2717 to its final value before loop start to ensure that this insn
2718 will always be executed, no matter how we exit. */
2719 tem
= gen_reg_rtx (v
->mode
);
2720 emit_insn_before (gen_move_insn (tem
, v
->dest_reg
), loop_start
);
2721 emit_insn_before (gen_move_insn (v
->dest_reg
, final_value
),
2724 if (loop_dump_stream
)
2725 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2726 REGNO (v
->dest_reg
), REGNO (tem
));
2732 /* This giv is splittable. If completely unrolling the loop, save the
2733 giv's initial value. Otherwise, save the constant zero for it. */
2735 if (unroll_type
== UNROLL_COMPLETELY
)
2737 /* It is not safe to use bl->initial_value here, because it may not
2738 be invariant. It is safe to use the initial value stored in
2739 the splittable_regs array if it is set. In rare cases, it won't
2740 be set, so then we do exactly the same thing as
2741 find_splittable_regs does to get a safe value. */
2742 rtx biv_initial_value
;
2744 if (splittable_regs
[bl
->regno
])
2745 biv_initial_value
= splittable_regs
[bl
->regno
];
2746 else if (GET_CODE (bl
->initial_value
) != REG
2747 || (REGNO (bl
->initial_value
) != bl
->regno
2748 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2749 biv_initial_value
= bl
->initial_value
;
2752 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2754 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2755 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2757 biv_initial_value
= tem
;
2759 biv_initial_value
= extend_value_for_giv (v
, biv_initial_value
);
2760 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2761 v
->add_val
, v
->mode
);
2768 /* If a giv was combined with another giv, then we can only split
2769 this giv if the giv it was combined with was reduced. This
2770 is because the value of v->new_reg is meaningless in this
2772 if (v
->same
&& ! v
->same
->new_reg
)
2774 if (loop_dump_stream
)
2775 fprintf (loop_dump_stream
,
2776 "giv combined with unreduced giv not split.\n");
2779 /* If the giv is an address destination, it could be something other
2780 than a simple register, these have to be treated differently. */
2781 else if (v
->giv_type
== DEST_REG
)
2783 /* If value is not a constant, register, or register plus
2784 constant, then compute its value into a register before
2785 loop start. This prevents invalid rtx sharing, and should
2786 generate better code. We can use bl->initial_value here
2787 instead of splittable_regs[bl->regno] because this code
2788 is going before the loop start. */
2789 if (unroll_type
== UNROLL_COMPLETELY
2790 && GET_CODE (value
) != CONST_INT
2791 && GET_CODE (value
) != REG
2792 && (GET_CODE (value
) != PLUS
2793 || GET_CODE (XEXP (value
, 0)) != REG
2794 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2796 rtx tem
= gen_reg_rtx (v
->mode
);
2797 record_base_value (REGNO (tem
), v
->add_val
, 0);
2798 emit_iv_add_mult (bl
->initial_value
, v
->mult_val
,
2799 v
->add_val
, tem
, loop
->start
);
2803 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2807 /* Splitting address givs is useful since it will often allow us
2808 to eliminate some increment insns for the base giv as
2811 /* If the addr giv is combined with a dest_reg giv, then all
2812 references to that dest reg will be remapped, which is NOT
2813 what we want for split addr regs. We always create a new
2814 register for the split addr giv, just to be safe. */
2816 /* If we have multiple identical address givs within a
2817 single instruction, then use a single pseudo reg for
2818 both. This is necessary in case one is a match_dup
2821 v
->const_adjust
= 0;
2825 v
->dest_reg
= v
->same_insn
->dest_reg
;
2826 if (loop_dump_stream
)
2827 fprintf (loop_dump_stream
,
2828 "Sharing address givs in insn %d\n",
2829 INSN_UID (v
->insn
));
2831 /* If multiple address GIVs have been combined with the
2832 same dest_reg GIV, do not create a new register for
2834 else if (unroll_type
!= UNROLL_COMPLETELY
2835 && v
->giv_type
== DEST_ADDR
2836 && v
->same
&& v
->same
->giv_type
== DEST_ADDR
2837 && v
->same
->unrolled
2838 /* combine_givs_p may return true for some cases
2839 where the add and mult values are not equal.
2840 To share a register here, the values must be
2842 && rtx_equal_p (v
->same
->mult_val
, v
->mult_val
)
2843 && rtx_equal_p (v
->same
->add_val
, v
->add_val
)
2844 /* If the memory references have different modes,
2845 then the address may not be valid and we must
2846 not share registers. */
2847 && verify_addresses (v
, giv_inc
, unroll_number
))
2849 v
->dest_reg
= v
->same
->dest_reg
;
2852 else if (unroll_type
!= UNROLL_COMPLETELY
)
2854 /* If not completely unrolling the loop, then create a new
2855 register to hold the split value of the DEST_ADDR giv.
2856 Emit insn to initialize its value before loop start. */
2858 rtx tem
= gen_reg_rtx (v
->mode
);
2859 struct induction
*same
= v
->same
;
2860 rtx new_reg
= v
->new_reg
;
2861 record_base_value (REGNO (tem
), v
->add_val
, 0);
2863 /* If the address giv has a constant in its new_reg value,
2864 then this constant can be pulled out and put in value,
2865 instead of being part of the initialization code. */
2867 if (GET_CODE (new_reg
) == PLUS
2868 && GET_CODE (XEXP (new_reg
, 1)) == CONST_INT
)
2871 = plus_constant (tem
, INTVAL (XEXP (new_reg
, 1)));
2873 /* Only succeed if this will give valid addresses.
2874 Try to validate both the first and the last
2875 address resulting from loop unrolling, if
2876 one fails, then can't do const elim here. */
2877 if (verify_addresses (v
, giv_inc
, unroll_number
))
2879 /* Save the negative of the eliminated const, so
2880 that we can calculate the dest_reg's increment
2882 v
->const_adjust
= -INTVAL (XEXP (new_reg
, 1));
2884 new_reg
= XEXP (new_reg
, 0);
2885 if (loop_dump_stream
)
2886 fprintf (loop_dump_stream
,
2887 "Eliminating constant from giv %d\n",
2896 /* If the address hasn't been checked for validity yet, do so
2897 now, and fail completely if either the first or the last
2898 unrolled copy of the address is not a valid address
2899 for the instruction that uses it. */
2900 if (v
->dest_reg
== tem
2901 && ! verify_addresses (v
, giv_inc
, unroll_number
))
2903 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2904 if (v2
->same_insn
== v
)
2907 if (loop_dump_stream
)
2908 fprintf (loop_dump_stream
,
2909 "Invalid address for giv at insn %d\n",
2910 INSN_UID (v
->insn
));
2914 v
->new_reg
= new_reg
;
2917 /* We set this after the address check, to guarantee that
2918 the register will be initialized. */
2921 /* To initialize the new register, just move the value of
2922 new_reg into it. This is not guaranteed to give a valid
2923 instruction on machines with complex addressing modes.
2924 If we can't recognize it, then delete it and emit insns
2925 to calculate the value from scratch. */
2926 emit_insn_before (gen_rtx_SET (VOIDmode
, tem
,
2927 copy_rtx (v
->new_reg
)),
2929 if (recog_memoized (PREV_INSN (loop
->start
)) < 0)
2933 /* We can't use bl->initial_value to compute the initial
2934 value, because the loop may have been preconditioned.
2935 We must calculate it from NEW_REG. Try using
2936 force_operand instead of emit_iv_add_mult. */
2937 delete_insn (PREV_INSN (loop
->start
));
2940 ret
= force_operand (v
->new_reg
, tem
);
2942 emit_move_insn (tem
, ret
);
2943 sequence
= gen_sequence ();
2945 emit_insn_before (sequence
, loop
->start
);
2947 if (loop_dump_stream
)
2948 fprintf (loop_dump_stream
,
2949 "Invalid init insn, rewritten.\n");
2954 v
->dest_reg
= value
;
2956 /* Check the resulting address for validity, and fail
2957 if the resulting address would be invalid. */
2958 if (! verify_addresses (v
, giv_inc
, unroll_number
))
2960 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2961 if (v2
->same_insn
== v
)
2964 if (loop_dump_stream
)
2965 fprintf (loop_dump_stream
,
2966 "Invalid address for giv at insn %d\n",
2967 INSN_UID (v
->insn
));
2972 /* Store the value of dest_reg into the insn. This sharing
2973 will not be a problem as this insn will always be copied
2976 *v
->location
= v
->dest_reg
;
2978 /* If this address giv is combined with a dest reg giv, then
2979 save the base giv's induction pointer so that we will be
2980 able to handle this address giv properly. The base giv
2981 itself does not have to be splittable. */
2983 if (v
->same
&& v
->same
->giv_type
== DEST_REG
)
2984 addr_combined_regs
[REGNO (v
->same
->new_reg
)] = v
->same
;
2986 if (GET_CODE (v
->new_reg
) == REG
)
2988 /* This giv maybe hasn't been combined with any others.
2989 Make sure that it's giv is marked as splittable here. */
2991 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2993 /* Make it appear to depend upon itself, so that the
2994 giv will be properly split in the main loop above. */
2998 addr_combined_regs
[REGNO (v
->new_reg
)] = v
;
3002 if (loop_dump_stream
)
3003 fprintf (loop_dump_stream
, "DEST_ADDR giv being split.\n");
3009 /* Currently, unreduced giv's can't be split. This is not too much
3010 of a problem since unreduced giv's are not live across loop
3011 iterations anyways. When unrolling a loop completely though,
3012 it makes sense to reduce&split givs when possible, as this will
3013 result in simpler instructions, and will not require that a reg
3014 be live across loop iterations. */
3016 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
3017 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
3018 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
3024 /* Unreduced givs are only updated once by definition. Reduced givs
3025 are updated as many times as their biv is. Mark it so if this is
3026 a splittable register. Don't need to do anything for address givs
3027 where this may not be a register. */
3029 if (GET_CODE (v
->new_reg
) == REG
)
3033 count
= ivs
->reg_biv_class
[REGNO (v
->src_reg
)]->biv_count
;
3035 splittable_regs_updates
[REGNO (v
->new_reg
)] = count
;
3040 if (loop_dump_stream
)
3044 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
3046 else if (GET_CODE (v
->dest_reg
) != REG
)
3047 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
3049 regnum
= REGNO (v
->dest_reg
);
3050 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
3051 regnum
, INSN_UID (v
->insn
));
3058 /* Try to prove that the register is dead after the loop exits. Trace every
3059 loop exit looking for an insn that will always be executed, which sets
3060 the register to some value, and appears before the first use of the register
3061 is found. If successful, then return 1, otherwise return 0. */
3063 /* ?? Could be made more intelligent in the handling of jumps, so that
3064 it can search past if statements and other similar structures. */
3067 reg_dead_after_loop (loop
, reg
)
3068 const struct loop
*loop
;
3074 int label_count
= 0;
3076 /* In addition to checking all exits of this loop, we must also check
3077 all exits of inner nested loops that would exit this loop. We don't
3078 have any way to identify those, so we just give up if there are any
3079 such inner loop exits. */
3081 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
3084 if (label_count
!= loop
->exit_count
)
3087 /* HACK: Must also search the loop fall through exit, create a label_ref
3088 here which points to the loop->end, and append the loop_number_exit_labels
3090 label
= gen_rtx_LABEL_REF (VOIDmode
, loop
->end
);
3091 LABEL_NEXTREF (label
) = loop
->exit_labels
;
3093 for (; label
; label
= LABEL_NEXTREF (label
))
3095 /* Succeed if find an insn which sets the biv or if reach end of
3096 function. Fail if find an insn that uses the biv, or if come to
3097 a conditional jump. */
3099 insn
= NEXT_INSN (XEXP (label
, 0));
3102 code
= GET_CODE (insn
);
3103 if (GET_RTX_CLASS (code
) == 'i')
3107 if (reg_referenced_p (reg
, PATTERN (insn
)))
3110 set
= single_set (insn
);
3111 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
3115 if (code
== JUMP_INSN
)
3117 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3119 else if (!any_uncondjump_p (insn
)
3120 /* Prevent infinite loop following infinite loops. */
3121 || jump_count
++ > 20)
3124 insn
= JUMP_LABEL (insn
);
3127 insn
= NEXT_INSN (insn
);
3131 /* Success, the register is dead on all loop exits. */
3135 /* Try to calculate the final value of the biv, the value it will have at
3136 the end of the loop. If we can do it, return that value. */
3139 final_biv_value (loop
, bl
)
3140 const struct loop
*loop
;
3141 struct iv_class
*bl
;
3143 rtx loop_end
= loop
->end
;
3144 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3147 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3149 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3152 /* The final value for reversed bivs must be calculated differently than
3153 for ordinary bivs. In this case, there is already an insn after the
3154 loop which sets this biv's final value (if necessary), and there are
3155 no other loop exits, so we can return any value. */
3158 if (loop_dump_stream
)
3159 fprintf (loop_dump_stream
,
3160 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3165 /* Try to calculate the final value as initial value + (number of iterations
3166 * increment). For this to work, increment must be invariant, the only
3167 exit from the loop must be the fall through at the bottom (otherwise
3168 it may not have its final value when the loop exits), and the initial
3169 value of the biv must be invariant. */
3171 if (n_iterations
!= 0
3172 && ! loop
->exit_count
3173 && loop_invariant_p (loop
, bl
->initial_value
))
3175 increment
= biv_total_increment (bl
);
3177 if (increment
&& loop_invariant_p (loop
, increment
))
3179 /* Can calculate the loop exit value, emit insns after loop
3180 end to calculate this value into a temporary register in
3181 case it is needed later. */
3183 tem
= gen_reg_rtx (bl
->biv
->mode
);
3184 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3185 /* Make sure loop_end is not the last insn. */
3186 if (NEXT_INSN (loop_end
) == 0)
3187 emit_note_after (NOTE_INSN_DELETED
, loop_end
);
3188 emit_iv_add_mult (increment
, GEN_INT (n_iterations
),
3189 bl
->initial_value
, tem
, NEXT_INSN (loop_end
));
3191 if (loop_dump_stream
)
3192 fprintf (loop_dump_stream
,
3193 "Final biv value for %d, calculated.\n", bl
->regno
);
3199 /* Check to see if the biv is dead at all loop exits. */
3200 if (reg_dead_after_loop (loop
, bl
->biv
->src_reg
))
3202 if (loop_dump_stream
)
3203 fprintf (loop_dump_stream
,
3204 "Final biv value for %d, biv dead after loop exit.\n",
3213 /* Try to calculate the final value of the giv, the value it will have at
3214 the end of the loop. If we can do it, return that value. */
3217 final_giv_value (loop
, v
)
3218 const struct loop
*loop
;
3219 struct induction
*v
;
3221 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3222 struct iv_class
*bl
;
3225 rtx insert_before
, seq
;
3226 rtx loop_end
= loop
->end
;
3227 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3229 bl
= ivs
->reg_biv_class
[REGNO (v
->src_reg
)];
3231 /* The final value for givs which depend on reversed bivs must be calculated
3232 differently than for ordinary givs. In this case, there is already an
3233 insn after the loop which sets this giv's final value (if necessary),
3234 and there are no other loop exits, so we can return any value. */
3237 if (loop_dump_stream
)
3238 fprintf (loop_dump_stream
,
3239 "Final giv value for %d, depends on reversed biv\n",
3240 REGNO (v
->dest_reg
));
3244 /* Try to calculate the final value as a function of the biv it depends
3245 upon. The only exit from the loop must be the fall through at the bottom
3246 (otherwise it may not have its final value when the loop exits). */
3248 /* ??? Can calculate the final giv value by subtracting off the
3249 extra biv increments times the giv's mult_val. The loop must have
3250 only one exit for this to work, but the loop iterations does not need
3253 if (n_iterations
!= 0
3254 && ! loop
->exit_count
)
3256 /* ?? It is tempting to use the biv's value here since these insns will
3257 be put after the loop, and hence the biv will have its final value
3258 then. However, this fails if the biv is subsequently eliminated.
3259 Perhaps determine whether biv's are eliminable before trying to
3260 determine whether giv's are replaceable so that we can use the
3261 biv value here if it is not eliminable. */
3263 /* We are emitting code after the end of the loop, so we must make
3264 sure that bl->initial_value is still valid then. It will still
3265 be valid if it is invariant. */
3267 increment
= biv_total_increment (bl
);
3269 if (increment
&& loop_invariant_p (loop
, increment
)
3270 && loop_invariant_p (loop
, bl
->initial_value
))
3272 /* Can calculate the loop exit value of its biv as
3273 (n_iterations * increment) + initial_value */
3275 /* The loop exit value of the giv is then
3276 (final_biv_value - extra increments) * mult_val + add_val.
3277 The extra increments are any increments to the biv which
3278 occur in the loop after the giv's value is calculated.
3279 We must search from the insn that sets the giv to the end
3280 of the loop to calculate this value. */
3282 insert_before
= NEXT_INSN (loop_end
);
3284 /* Put the final biv value in tem. */
3285 tem
= gen_reg_rtx (v
->mode
);
3286 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3287 emit_iv_add_mult (extend_value_for_giv (v
, increment
),
3288 GEN_INT (n_iterations
),
3289 extend_value_for_giv (v
, bl
->initial_value
),
3290 tem
, insert_before
);
3292 /* Subtract off extra increments as we find them. */
3293 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3294 insn
= NEXT_INSN (insn
))
3296 struct induction
*biv
;
3298 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3299 if (biv
->insn
== insn
)
3302 tem
= expand_binop (GET_MODE (tem
), sub_optab
, tem
,
3303 biv
->add_val
, NULL_RTX
, 0,
3305 seq
= gen_sequence ();
3307 emit_insn_before (seq
, insert_before
);
3311 /* Now calculate the giv's final value. */
3312 emit_iv_add_mult (tem
, v
->mult_val
, v
->add_val
, tem
, insert_before
);
3314 if (loop_dump_stream
)
3315 fprintf (loop_dump_stream
,
3316 "Final giv value for %d, calc from biv's value.\n",
3317 REGNO (v
->dest_reg
));
3323 /* Replaceable giv's should never reach here. */
3327 /* Check to see if the biv is dead at all loop exits. */
3328 if (reg_dead_after_loop (loop
, v
->dest_reg
))
3330 if (loop_dump_stream
)
3331 fprintf (loop_dump_stream
,
3332 "Final giv value for %d, giv dead after loop exit.\n",
3333 REGNO (v
->dest_reg
));
3341 /* Look back before LOOP->START for then insn that sets REG and return
3342 the equivalent constant if there is a REG_EQUAL note otherwise just
3343 the SET_SRC of REG. */
3346 loop_find_equiv_value (loop
, reg
)
3347 const struct loop
*loop
;
3350 rtx loop_start
= loop
->start
;
3355 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3357 if (GET_CODE (insn
) == CODE_LABEL
)
3360 else if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3362 /* We found the last insn before the loop that sets the register.
3363 If it sets the entire register, and has a REG_EQUAL note,
3364 then use the value of the REG_EQUAL note. */
3365 if ((set
= single_set (insn
))
3366 && (SET_DEST (set
) == reg
))
3368 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3370 /* Only use the REG_EQUAL note if it is a constant.
3371 Other things, divide in particular, will cause
3372 problems later if we use them. */
3373 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3374 && CONSTANT_P (XEXP (note
, 0)))
3375 ret
= XEXP (note
, 0);
3377 ret
= SET_SRC (set
);
3379 /* We cannot do this if it changes between the
3380 assignment and loop start though. */
3381 if (modified_between_p (ret
, insn
, loop_start
))
3390 /* Return a simplified rtx for the expression OP - REG.
3392 REG must appear in OP, and OP must be a register or the sum of a register
3395 Thus, the return value must be const0_rtx or the second term.
3397 The caller is responsible for verifying that REG appears in OP and OP has
3401 subtract_reg_term (op
, reg
)
3406 if (GET_CODE (op
) == PLUS
)
3408 if (XEXP (op
, 0) == reg
)
3409 return XEXP (op
, 1);
3410 else if (XEXP (op
, 1) == reg
)
3411 return XEXP (op
, 0);
3413 /* OP does not contain REG as a term. */
3417 /* Find and return register term common to both expressions OP0 and
3418 OP1 or NULL_RTX if no such term exists. Each expression must be a
3419 REG or a PLUS of a REG. */
3422 find_common_reg_term (op0
, op1
)
3425 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3426 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3433 if (GET_CODE (op0
) == PLUS
)
3434 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3436 op01
= const0_rtx
, op00
= op0
;
3438 if (GET_CODE (op1
) == PLUS
)
3439 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3441 op11
= const0_rtx
, op10
= op1
;
3443 /* Find and return common register term if present. */
3444 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3446 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3450 /* No common register term found. */
3454 /* Determine the loop iterator and calculate the number of loop
3455 iterations. Returns the exact number of loop iterations if it can
3456 be calculated, otherwise returns zero. */
3458 unsigned HOST_WIDE_INT
3459 loop_iterations (loop
)
3462 struct loop_info
*loop_info
= LOOP_INFO (loop
);
3463 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3464 rtx comparison
, comparison_value
;
3465 rtx iteration_var
, initial_value
, increment
, final_value
;
3466 enum rtx_code comparison_code
;
3467 HOST_WIDE_INT abs_inc
;
3468 unsigned HOST_WIDE_INT abs_diff
;
3471 int unsigned_p
, compare_dir
, final_larger
;
3474 struct iv_class
*bl
;
3476 loop_info
->n_iterations
= 0;
3477 loop_info
->initial_value
= 0;
3478 loop_info
->initial_equiv_value
= 0;
3479 loop_info
->comparison_value
= 0;
3480 loop_info
->final_value
= 0;
3481 loop_info
->final_equiv_value
= 0;
3482 loop_info
->increment
= 0;
3483 loop_info
->iteration_var
= 0;
3484 loop_info
->unroll_number
= 1;
3487 /* We used to use prev_nonnote_insn here, but that fails because it might
3488 accidentally get the branch for a contained loop if the branch for this
3489 loop was deleted. We can only trust branches immediately before the
3491 last_loop_insn
= PREV_INSN (loop
->end
);
3493 /* ??? We should probably try harder to find the jump insn
3494 at the end of the loop. The following code assumes that
3495 the last loop insn is a jump to the top of the loop. */
3496 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3498 if (loop_dump_stream
)
3499 fprintf (loop_dump_stream
,
3500 "Loop iterations: No final conditional branch found.\n");
3504 /* If there is a more than a single jump to the top of the loop
3505 we cannot (easily) determine the iteration count. */
3506 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3508 if (loop_dump_stream
)
3509 fprintf (loop_dump_stream
,
3510 "Loop iterations: Loop has multiple back edges.\n");
3514 /* Find the iteration variable. If the last insn is a conditional
3515 branch, and the insn before tests a register value, make that the
3516 iteration variable. */
3518 comparison
= get_condition_for_loop (loop
, last_loop_insn
);
3519 if (comparison
== 0)
3521 if (loop_dump_stream
)
3522 fprintf (loop_dump_stream
,
3523 "Loop iterations: No final comparison found.\n");
3527 /* ??? Get_condition may switch position of induction variable and
3528 invariant register when it canonicalizes the comparison. */
3530 comparison_code
= GET_CODE (comparison
);
3531 iteration_var
= XEXP (comparison
, 0);
3532 comparison_value
= XEXP (comparison
, 1);
3534 if (GET_CODE (iteration_var
) != REG
)
3536 if (loop_dump_stream
)
3537 fprintf (loop_dump_stream
,
3538 "Loop iterations: Comparison not against register.\n");
3542 /* The only new registers that are created before loop iterations
3543 are givs made from biv increments or registers created by
3544 load_mems. In the latter case, it is possible that try_copy_prop
3545 will propagate a new pseudo into the old iteration register but
3546 this will be marked by having the REG_USERVAR_P bit set. */
3548 if ((unsigned) REGNO (iteration_var
) >= ivs
->reg_iv_type
->num_elements
3549 && ! REG_USERVAR_P (iteration_var
))
3552 /* Determine the initial value of the iteration variable, and the amount
3553 that it is incremented each loop. Use the tables constructed by
3554 the strength reduction pass to calculate these values. */
3556 /* Clear the result values, in case no answer can be found. */
3560 /* The iteration variable can be either a giv or a biv. Check to see
3561 which it is, and compute the variable's initial value, and increment
3562 value if possible. */
3564 /* If this is a new register, can't handle it since we don't have any
3565 reg_iv_type entry for it. */
3566 if ((unsigned) REGNO (iteration_var
) >= ivs
->reg_iv_type
->num_elements
)
3568 if (loop_dump_stream
)
3569 fprintf (loop_dump_stream
,
3570 "Loop iterations: No reg_iv_type entry for iteration var.\n");
3574 /* Reject iteration variables larger than the host wide int size, since they
3575 could result in a number of iterations greater than the range of our
3576 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
3577 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
3578 > HOST_BITS_PER_WIDE_INT
))
3580 if (loop_dump_stream
)
3581 fprintf (loop_dump_stream
,
3582 "Loop iterations: Iteration var rejected because mode too large.\n");
3585 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
3587 if (loop_dump_stream
)
3588 fprintf (loop_dump_stream
,
3589 "Loop iterations: Iteration var not an integer.\n");
3592 else if (REG_IV_TYPE (ivs
, REGNO (iteration_var
)) == BASIC_INDUCT
)
3594 /* When reg_iv_type / reg_iv_info is resized for biv increments
3595 that are turned into givs, reg_biv_class is not resized.
3596 So check here that we don't make an out-of-bounds access. */
3597 if (REGNO (iteration_var
) >= max_reg_before_loop
)
3600 /* Grab initial value, only useful if it is a constant. */
3601 bl
= ivs
->reg_biv_class
[REGNO (iteration_var
)];
3602 initial_value
= bl
->initial_value
;
3604 increment
= biv_total_increment (bl
);
3606 else if (REG_IV_TYPE (ivs
, REGNO (iteration_var
)) == GENERAL_INDUCT
)
3608 HOST_WIDE_INT offset
= 0;
3609 struct induction
*v
= REG_IV_INFO (ivs
, REGNO (iteration_var
));
3610 rtx biv_initial_value
;
3612 if (REGNO (v
->src_reg
) >= max_reg_before_loop
)
3615 bl
= ivs
->reg_biv_class
[REGNO (v
->src_reg
)];
3617 /* Increment value is mult_val times the increment value of the biv. */
3619 increment
= biv_total_increment (bl
);
3622 struct induction
*biv_inc
;
3624 increment
= fold_rtx_mult_add (v
->mult_val
,
3625 extend_value_for_giv (v
, increment
),
3626 const0_rtx
, v
->mode
);
3627 /* The caller assumes that one full increment has occured at the
3628 first loop test. But that's not true when the biv is incremented
3629 after the giv is set (which is the usual case), e.g.:
3630 i = 6; do {;} while (i++ < 9) .
3631 Therefore, we bias the initial value by subtracting the amount of
3632 the increment that occurs between the giv set and the giv test. */
3633 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
3635 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
3636 offset
-= INTVAL (biv_inc
->add_val
);
3638 offset
*= INTVAL (v
->mult_val
);
3640 if (loop_dump_stream
)
3641 fprintf (loop_dump_stream
,
3642 "Loop iterations: Giv iterator, initial value bias %ld.\n",
3645 /* Initial value is mult_val times the biv's initial value plus
3646 add_val. Only useful if it is a constant. */
3647 biv_initial_value
= extend_value_for_giv (v
, bl
->initial_value
);
3649 = fold_rtx_mult_add (v
->mult_val
,
3650 plus_constant (biv_initial_value
, offset
),
3651 v
->add_val
, v
->mode
);
3655 if (loop_dump_stream
)
3656 fprintf (loop_dump_stream
,
3657 "Loop iterations: Not basic or general induction var.\n");
3661 if (initial_value
== 0)
3666 switch (comparison_code
)
3681 /* Cannot determine loop iterations with this case. */
3700 /* If the comparison value is an invariant register, then try to find
3701 its value from the insns before the start of the loop. */
3703 final_value
= comparison_value
;
3704 if (GET_CODE (comparison_value
) == REG
3705 && loop_invariant_p (loop
, comparison_value
))
3707 final_value
= loop_find_equiv_value (loop
, comparison_value
);
3709 /* If we don't get an invariant final value, we are better
3710 off with the original register. */
3711 if (! loop_invariant_p (loop
, final_value
))
3712 final_value
= comparison_value
;
3715 /* Calculate the approximate final value of the induction variable
3716 (on the last successful iteration). The exact final value
3717 depends on the branch operator, and increment sign. It will be
3718 wrong if the iteration variable is not incremented by one each
3719 time through the loop and (comparison_value + off_by_one -
3720 initial_value) % increment != 0.
3721 ??? Note that the final_value may overflow and thus final_larger
3722 will be bogus. A potentially infinite loop will be classified
3723 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3725 final_value
= plus_constant (final_value
, off_by_one
);
3727 /* Save the calculated values describing this loop's bounds, in case
3728 precondition_loop_p will need them later. These values can not be
3729 recalculated inside precondition_loop_p because strength reduction
3730 optimizations may obscure the loop's structure.
3732 These values are only required by precondition_loop_p and insert_bct
3733 whenever the number of iterations cannot be computed at compile time.
3734 Only the difference between final_value and initial_value is
3735 important. Note that final_value is only approximate. */
3736 loop_info
->initial_value
= initial_value
;
3737 loop_info
->comparison_value
= comparison_value
;
3738 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3739 loop_info
->increment
= increment
;
3740 loop_info
->iteration_var
= iteration_var
;
3741 loop_info
->comparison_code
= comparison_code
;
3744 /* Try to determine the iteration count for loops such
3745 as (for i = init; i < init + const; i++). When running the
3746 loop optimization twice, the first pass often converts simple
3747 loops into this form. */
3749 if (REG_P (initial_value
))
3755 reg1
= initial_value
;
3756 if (GET_CODE (final_value
) == PLUS
)
3757 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3759 reg2
= final_value
, const2
= const0_rtx
;
3761 /* Check for initial_value = reg1, final_value = reg2 + const2,
3762 where reg1 != reg2. */
3763 if (REG_P (reg2
) && reg2
!= reg1
)
3767 /* Find what reg1 is equivalent to. Hopefully it will
3768 either be reg2 or reg2 plus a constant. */
3769 temp
= loop_find_equiv_value (loop
, reg1
);
3771 if (find_common_reg_term (temp
, reg2
))
3772 initial_value
= temp
;
3775 /* Find what reg2 is equivalent to. Hopefully it will
3776 either be reg1 or reg1 plus a constant. Let's ignore
3777 the latter case for now since it is not so common. */
3778 temp
= loop_find_equiv_value (loop
, reg2
);
3780 if (temp
== loop_info
->iteration_var
)
3781 temp
= initial_value
;
3783 final_value
= (const2
== const0_rtx
)
3784 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3787 else if (loop
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3791 /* When running the loop optimizer twice, check_dbra_loop
3792 further obfuscates reversible loops of the form:
3793 for (i = init; i < init + const; i++). We often end up with
3794 final_value = 0, initial_value = temp, temp = temp2 - init,
3795 where temp2 = init + const. If the loop has a vtop we
3796 can replace initial_value with const. */
3798 temp
= loop_find_equiv_value (loop
, reg1
);
3800 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3802 rtx temp2
= loop_find_equiv_value (loop
, XEXP (temp
, 0));
3804 if (GET_CODE (temp2
) == PLUS
3805 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3806 initial_value
= XEXP (temp2
, 1);
3811 /* If have initial_value = reg + const1 and final_value = reg +
3812 const2, then replace initial_value with const1 and final_value
3813 with const2. This should be safe since we are protected by the
3814 initial comparison before entering the loop if we have a vtop.
3815 For example, a + b < a + c is not equivalent to b < c for all a
3816 when using modulo arithmetic.
3818 ??? Without a vtop we could still perform the optimization if we check
3819 the initial and final values carefully. */
3821 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3823 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3824 final_value
= subtract_reg_term (final_value
, reg_term
);
3827 loop_info
->initial_equiv_value
= initial_value
;
3828 loop_info
->final_equiv_value
= final_value
;
3830 /* For EQ comparison loops, we don't have a valid final value.
3831 Check this now so that we won't leave an invalid value if we
3832 return early for any other reason. */
3833 if (comparison_code
== EQ
)
3834 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3838 if (loop_dump_stream
)
3839 fprintf (loop_dump_stream
,
3840 "Loop iterations: Increment value can't be calculated.\n");
3844 if (GET_CODE (increment
) != CONST_INT
)
3846 /* If we have a REG, check to see if REG holds a constant value. */
3847 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3848 clear if it is worthwhile to try to handle such RTL. */
3849 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3850 increment
= loop_find_equiv_value (loop
, increment
);
3852 if (GET_CODE (increment
) != CONST_INT
)
3854 if (loop_dump_stream
)
3856 fprintf (loop_dump_stream
,
3857 "Loop iterations: Increment value not constant ");
3858 print_rtl (loop_dump_stream
, increment
);
3859 fprintf (loop_dump_stream
, ".\n");
3863 loop_info
->increment
= increment
;
3866 if (GET_CODE (initial_value
) != CONST_INT
)
3868 if (loop_dump_stream
)
3870 fprintf (loop_dump_stream
,
3871 "Loop iterations: Initial value not constant ");
3872 print_rtl (loop_dump_stream
, initial_value
);
3873 fprintf (loop_dump_stream
, ".\n");
3877 else if (comparison_code
== EQ
)
3879 if (loop_dump_stream
)
3880 fprintf (loop_dump_stream
, "Loop iterations: EQ comparison loop.\n");
3883 else if (GET_CODE (final_value
) != CONST_INT
)
3885 if (loop_dump_stream
)
3887 fprintf (loop_dump_stream
,
3888 "Loop iterations: Final value not constant ");
3889 print_rtl (loop_dump_stream
, final_value
);
3890 fprintf (loop_dump_stream
, ".\n");
3895 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3898 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3899 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3900 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3901 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3903 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3904 - (INTVAL (final_value
) < INTVAL (initial_value
));
3906 if (INTVAL (increment
) > 0)
3908 else if (INTVAL (increment
) == 0)
3913 /* There are 27 different cases: compare_dir = -1, 0, 1;
3914 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3915 There are 4 normal cases, 4 reverse cases (where the iteration variable
3916 will overflow before the loop exits), 4 infinite loop cases, and 15
3917 immediate exit (0 or 1 iteration depending on loop type) cases.
3918 Only try to optimize the normal cases. */
3920 /* (compare_dir/final_larger/increment_dir)
3921 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3922 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3923 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3924 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3926 /* ?? If the meaning of reverse loops (where the iteration variable
3927 will overflow before the loop exits) is undefined, then could
3928 eliminate all of these special checks, and just always assume
3929 the loops are normal/immediate/infinite. Note that this means
3930 the sign of increment_dir does not have to be known. Also,
3931 since it does not really hurt if immediate exit loops or infinite loops
3932 are optimized, then that case could be ignored also, and hence all
3933 loops can be optimized.
3935 According to ANSI Spec, the reverse loop case result is undefined,
3936 because the action on overflow is undefined.
3938 See also the special test for NE loops below. */
3940 if (final_larger
== increment_dir
&& final_larger
!= 0
3941 && (final_larger
== compare_dir
|| compare_dir
== 0))
3946 if (loop_dump_stream
)
3947 fprintf (loop_dump_stream
, "Loop iterations: Not normal loop.\n");
3951 /* Calculate the number of iterations, final_value is only an approximation,
3952 so correct for that. Note that abs_diff and n_iterations are
3953 unsigned, because they can be as large as 2^n - 1. */
3955 abs_inc
= INTVAL (increment
);
3957 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
3958 else if (abs_inc
< 0)
3960 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
3966 /* For NE tests, make sure that the iteration variable won't miss
3967 the final value. If abs_diff mod abs_incr is not zero, then the
3968 iteration variable will overflow before the loop exits, and we
3969 can not calculate the number of iterations. */
3970 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
3973 /* Note that the number of iterations could be calculated using
3974 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3975 handle potential overflow of the summation. */
3976 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
3977 return loop_info
->n_iterations
;
3980 /* Replace uses of split bivs with their split pseudo register. This is
3981 for original instructions which remain after loop unrolling without
3985 remap_split_bivs (loop
, x
)
3989 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3990 register enum rtx_code code
;
3992 register const char *fmt
;
3997 code
= GET_CODE (x
);
4012 /* If non-reduced/final-value givs were split, then this would also
4013 have to remap those givs also. */
4015 if (REGNO (x
) < max_reg_before_loop
4016 && REG_IV_TYPE (ivs
, REGNO (x
)) == BASIC_INDUCT
)
4017 return ivs
->reg_biv_class
[REGNO (x
)]->biv
->src_reg
;
4024 fmt
= GET_RTX_FORMAT (code
);
4025 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
4028 XEXP (x
, i
) = remap_split_bivs (loop
, XEXP (x
, i
));
4029 else if (fmt
[i
] == 'E')
4032 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
4033 XVECEXP (x
, i
, j
) = remap_split_bivs (loop
, XVECEXP (x
, i
, j
));
4039 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
4040 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
4041 return 0. COPY_START is where we can start looking for the insns
4042 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
4045 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
4046 must dominate LAST_UID.
4048 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4049 may not dominate LAST_UID.
4051 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4052 must dominate LAST_UID. */
4055 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
4062 int passed_jump
= 0;
4063 rtx p
= NEXT_INSN (copy_start
);
4065 while (INSN_UID (p
) != first_uid
)
4067 if (GET_CODE (p
) == JUMP_INSN
)
4069 /* Could not find FIRST_UID. */
4075 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4076 if (! INSN_P (p
) || ! dead_or_set_regno_p (p
, regno
))
4079 /* FIRST_UID is always executed. */
4080 if (passed_jump
== 0)
4083 while (INSN_UID (p
) != last_uid
)
4085 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4086 can not be sure that FIRST_UID dominates LAST_UID. */
4087 if (GET_CODE (p
) == CODE_LABEL
)
4089 /* Could not find LAST_UID, but we reached the end of the loop, so
4091 else if (p
== copy_end
)
4096 /* FIRST_UID is always executed if LAST_UID is executed. */
4100 /* This routine is called when the number of iterations for the unrolled
4101 loop is one. The goal is to identify a loop that begins with an
4102 unconditional branch to the loop continuation note (or a label just after).
4103 In this case, the unconditional branch that starts the loop needs to be
4104 deleted so that we execute the single iteration. */
4107 ujump_to_loop_cont (loop_start
, loop_cont
)
4111 rtx x
, label
, label_ref
;
4113 /* See if loop start, or the next insn is an unconditional jump. */
4114 loop_start
= next_nonnote_insn (loop_start
);
4116 x
= pc_set (loop_start
);
4120 label_ref
= SET_SRC (x
);
4124 /* Examine insn after loop continuation note. Return if not a label. */
4125 label
= next_nonnote_insn (loop_cont
);
4126 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
4129 /* Return the loop start if the branch label matches the code label. */
4130 if (CODE_LABEL_NUMBER (label
) == CODE_LABEL_NUMBER (XEXP (label_ref
, 0)))