1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001, 2002
3 Free Software Foundation, Inc.
4 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 /* Try to unroll a loop, and split induction variables.
25 Loops for which the number of iterations can be calculated exactly are
26 handled specially. If the number of iterations times the insn_count is
27 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
28 Otherwise, we try to unroll the loop a number of times modulo the number
29 of iterations, so that only one exit test will be needed. It is unrolled
30 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
33 Otherwise, if the number of iterations can be calculated exactly at
34 run time, and the loop is always entered at the top, then we try to
35 precondition the loop. That is, at run time, calculate how many times
36 the loop will execute, and then execute the loop body a few times so
37 that the remaining iterations will be some multiple of 4 (or 2 if the
38 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
39 with only one exit test needed at the end of the loop.
41 Otherwise, if the number of iterations can not be calculated exactly,
42 not even at run time, then we still unroll the loop a number of times
43 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
44 but there must be an exit test after each copy of the loop body.
46 For each induction variable, which is dead outside the loop (replaceable)
47 or for which we can easily calculate the final value, if we can easily
48 calculate its value at each place where it is set as a function of the
49 current loop unroll count and the variable's value at loop entry, then
50 the induction variable is split into `N' different variables, one for
51 each copy of the loop body. One variable is live across the backward
52 branch, and the others are all calculated as a function of this variable.
53 This helps eliminate data dependencies, and leads to further opportunities
56 /* Possible improvements follow: */
58 /* ??? Add an extra pass somewhere to determine whether unrolling will
59 give any benefit. E.g. after generating all unrolled insns, compute the
60 cost of all insns and compare against cost of insns in rolled loop.
62 - On traditional architectures, unrolling a non-constant bound loop
63 is a win if there is a giv whose only use is in memory addresses, the
64 memory addresses can be split, and hence giv increments can be
66 - It is also a win if the loop is executed many times, and preconditioning
67 can be performed for the loop.
68 Add code to check for these and similar cases. */
70 /* ??? Improve control of which loops get unrolled. Could use profiling
71 info to only unroll the most commonly executed loops. Perhaps have
72 a user specifiable 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. */
136 #include "coretypes.h"
140 #include "insn-config.h"
141 #include "integrate.h"
145 #include "function.h"
149 #include "hard-reg-set.h"
150 #include "basic-block.h"
155 /* The prime factors looked for when trying to unroll a loop by some
156 number which is modulo the total number of iterations. Just checking
157 for these 4 prime factors will find at least one factor for 75% of
158 all numbers theoretically. Practically speaking, this will succeed
159 almost all of the time since loops are generally a multiple of 2
162 #define NUM_FACTORS 4
164 static struct _factor
{ const int factor
; int count
; }
165 factors
[NUM_FACTORS
] = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
167 /* Describes the different types of loop unrolling performed. */
176 /* Indexed by register number, if nonzero, then it contains a pointer
177 to a struct induction for a DEST_REG giv which has been combined with
178 one of more address givs. This is needed because whenever such a DEST_REG
179 giv is modified, we must modify the value of all split address givs
180 that were combined with this DEST_REG giv. */
182 static struct induction
**addr_combined_regs
;
184 /* Indexed by register number, if this is a splittable induction variable,
185 then this will hold the current value of the register, which depends on the
188 static rtx
*splittable_regs
;
190 /* Indexed by register number, if this is a splittable induction variable,
191 then this will hold the number of instructions in the loop that modify
192 the induction variable. Used to ensure that only the last insn modifying
193 a split iv will update the original iv of the dest. */
195 static int *splittable_regs_updates
;
197 /* Forward declarations. */
199 static rtx simplify_cmp_and_jump_insns
PARAMS ((enum rtx_code
,
202 static void init_reg_map
PARAMS ((struct inline_remap
*, int));
203 static rtx calculate_giv_inc
PARAMS ((rtx
, rtx
, unsigned int));
204 static rtx initial_reg_note_copy
PARAMS ((rtx
, struct inline_remap
*));
205 static void final_reg_note_copy
PARAMS ((rtx
*, struct inline_remap
*));
206 static void copy_loop_body
PARAMS ((struct loop
*, rtx
, rtx
,
207 struct inline_remap
*, rtx
, int,
208 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
209 static int find_splittable_regs
PARAMS ((const struct loop
*,
210 enum unroll_types
, int));
211 static int find_splittable_givs
PARAMS ((const struct loop
*,
212 struct iv_class
*, enum unroll_types
,
214 static int reg_dead_after_loop
PARAMS ((const struct loop
*, rtx
));
215 static rtx fold_rtx_mult_add
PARAMS ((rtx
, rtx
, rtx
, enum machine_mode
));
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 STRENGTH_REDUCTION_P indicates whether information generated in the
226 strength reduction pass is available.
228 This function is intended to be called from within `strength_reduce'
232 unroll_loop (loop
, insn_count
, strength_reduce_p
)
235 int strength_reduce_p
;
237 struct loop_info
*loop_info
= LOOP_INFO (loop
);
238 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
241 unsigned HOST_WIDE_INT temp
;
242 int unroll_number
= 1;
243 rtx copy_start
, copy_end
;
244 rtx insn
, sequence
, pattern
, tem
;
245 int max_labelno
, max_insnno
;
247 struct inline_remap
*map
;
248 char *local_label
= NULL
;
250 unsigned int max_local_regnum
;
251 unsigned int maxregnum
;
255 int splitting_not_safe
= 0;
256 enum unroll_types unroll_type
= UNROLL_NAIVE
;
257 int loop_preconditioned
= 0;
259 /* This points to the last real insn in the loop, which should be either
260 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
263 rtx loop_start
= loop
->start
;
264 rtx loop_end
= loop
->end
;
266 /* Don't bother unrolling huge loops. Since the minimum factor is
267 two, loops greater than one half of MAX_UNROLLED_INSNS will never
269 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
271 if (loop_dump_stream
)
272 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
276 /* Determine type of unroll to perform. Depends on the number of iterations
277 and the size of the loop. */
279 /* If there is no strength reduce info, then set
280 loop_info->n_iterations to zero. This can happen if
281 strength_reduce can't find any bivs in the loop. A value of zero
282 indicates that the number of iterations could not be calculated. */
284 if (! strength_reduce_p
)
285 loop_info
->n_iterations
= 0;
287 if (loop_dump_stream
&& loop_info
->n_iterations
> 0)
288 fprintf (loop_dump_stream
, "Loop unrolling: " HOST_WIDE_INT_PRINT_DEC
289 " iterations.\n", loop_info
->n_iterations
);
291 /* Find and save a pointer to the last nonnote insn in the loop. */
293 last_loop_insn
= prev_nonnote_insn (loop_end
);
295 /* Calculate how many times to unroll the loop. Indicate whether or
296 not the loop is being completely unrolled. */
298 if (loop_info
->n_iterations
== 1)
300 /* Handle the case where the loop begins with an unconditional
301 jump to the loop condition. Make sure to delete the jump
302 insn, otherwise the loop body will never execute. */
304 /* FIXME this actually checks for a jump to the continue point, which
305 is not the same as the condition in a for loop. As a result, this
306 optimization fails for most for loops. We should really use flow
307 information rather than instruction pattern matching. */
308 rtx ujump
= ujump_to_loop_cont (loop
->start
, loop
->cont
);
310 /* If number of iterations is exactly 1, then eliminate the compare and
311 branch at the end of the loop since they will never be taken.
312 Then return, since no other action is needed here. */
314 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
315 don't do anything. */
317 if (GET_CODE (last_loop_insn
) == BARRIER
)
319 /* Delete the jump insn. This will delete the barrier also. */
320 last_loop_insn
= PREV_INSN (last_loop_insn
);
323 if (ujump
&& GET_CODE (last_loop_insn
) == JUMP_INSN
)
326 rtx prev
= PREV_INSN (last_loop_insn
);
328 delete_related_insns (last_loop_insn
);
330 /* The immediately preceding insn may be a compare which must be
332 if (only_sets_cc0_p (prev
))
333 delete_related_insns (prev
);
336 delete_related_insns (ujump
);
338 /* Remove the loop notes since this is no longer a loop. */
340 delete_related_insns (loop
->vtop
);
342 delete_related_insns (loop
->cont
);
344 delete_related_insns (loop_start
);
346 delete_related_insns (loop_end
);
352 if (loop_info
->n_iterations
> 0
353 /* Avoid overflow in the next expression. */
354 && loop_info
->n_iterations
< (unsigned) MAX_UNROLLED_INSNS
355 && loop_info
->n_iterations
* insn_count
< (unsigned) MAX_UNROLLED_INSNS
)
357 unroll_number
= loop_info
->n_iterations
;
358 unroll_type
= UNROLL_COMPLETELY
;
360 else if (loop_info
->n_iterations
> 0)
362 /* Try to factor the number of iterations. Don't bother with the
363 general case, only using 2, 3, 5, and 7 will get 75% of all
364 numbers theoretically, and almost all in practice. */
366 for (i
= 0; i
< NUM_FACTORS
; i
++)
367 factors
[i
].count
= 0;
369 temp
= loop_info
->n_iterations
;
370 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
371 while (temp
% factors
[i
].factor
== 0)
374 temp
= temp
/ factors
[i
].factor
;
377 /* Start with the larger factors first so that we generally
378 get lots of unrolling. */
382 for (i
= 3; i
>= 0; i
--)
383 while (factors
[i
].count
--)
385 if (temp
* factors
[i
].factor
< (unsigned) MAX_UNROLLED_INSNS
)
387 unroll_number
*= factors
[i
].factor
;
388 temp
*= factors
[i
].factor
;
394 /* If we couldn't find any factors, then unroll as in the normal
396 if (unroll_number
== 1)
398 if (loop_dump_stream
)
399 fprintf (loop_dump_stream
, "Loop unrolling: No factors found.\n");
402 unroll_type
= UNROLL_MODULO
;
405 /* Default case, calculate number of times to unroll loop based on its
407 if (unroll_type
== UNROLL_NAIVE
)
409 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
411 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
417 /* Now we know how many times to unroll the loop. */
419 if (loop_dump_stream
)
420 fprintf (loop_dump_stream
, "Unrolling loop %d times.\n", unroll_number
);
422 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
424 /* Loops of these types can start with jump down to the exit condition
425 in rare circumstances.
427 Consider a pair of nested loops where the inner loop is part
428 of the exit code for the outer loop.
430 In this case jump.c will not duplicate the exit test for the outer
431 loop, so it will start with a jump to the exit code.
433 Then consider if the inner loop turns out to iterate once and
434 only once. We will end up deleting the jumps associated with
435 the inner loop. However, the loop notes are not removed from
436 the instruction stream.
438 And finally assume that we can compute the number of iterations
441 In this case unroll may want to unroll the outer loop even though
442 it starts with a jump to the outer loop's exit code.
444 We could try to optimize this case, but it hardly seems worth it.
445 Just return without unrolling the loop in such cases. */
448 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
449 insn
= NEXT_INSN (insn
);
450 if (GET_CODE (insn
) == JUMP_INSN
)
454 if (unroll_type
== UNROLL_COMPLETELY
)
456 /* Completely unrolling the loop: Delete the compare and branch at
457 the end (the last two instructions). This delete must done at the
458 very end of loop unrolling, to avoid problems with calls to
459 back_branch_in_range_p, which is called by find_splittable_regs.
460 All increments of splittable bivs/givs are changed to load constant
463 copy_start
= loop_start
;
465 /* Set insert_before to the instruction immediately after the JUMP_INSN
466 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
467 the loop will be correctly handled by copy_loop_body. */
468 insert_before
= NEXT_INSN (last_loop_insn
);
470 /* Set copy_end to the insn before the jump at the end of the loop. */
471 if (GET_CODE (last_loop_insn
) == BARRIER
)
472 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
473 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
475 copy_end
= PREV_INSN (last_loop_insn
);
477 /* The instruction immediately before the JUMP_INSN may be a compare
478 instruction which we do not want to copy. */
479 if (sets_cc0_p (PREV_INSN (copy_end
)))
480 copy_end
= PREV_INSN (copy_end
);
485 /* We currently can't unroll a loop if it doesn't end with a
486 JUMP_INSN. There would need to be a mechanism that recognizes
487 this case, and then inserts a jump after each loop body, which
488 jumps to after the last loop body. */
489 if (loop_dump_stream
)
490 fprintf (loop_dump_stream
,
491 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
495 else if (unroll_type
== UNROLL_MODULO
)
497 /* Partially unrolling the loop: The compare and branch at the end
498 (the last two instructions) must remain. Don't copy the compare
499 and branch instructions at the end of the loop. Insert the unrolled
500 code immediately before the compare/branch at the end so that the
501 code will fall through to them as before. */
503 copy_start
= loop_start
;
505 /* Set insert_before to the jump insn at the end of the loop.
506 Set copy_end to before the jump insn at the end of the loop. */
507 if (GET_CODE (last_loop_insn
) == BARRIER
)
509 insert_before
= PREV_INSN (last_loop_insn
);
510 copy_end
= PREV_INSN (insert_before
);
512 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
514 insert_before
= last_loop_insn
;
516 /* The instruction immediately before the JUMP_INSN may be a compare
517 instruction which we do not want to copy or delete. */
518 if (sets_cc0_p (PREV_INSN (insert_before
)))
519 insert_before
= PREV_INSN (insert_before
);
521 copy_end
= PREV_INSN (insert_before
);
525 /* We currently can't unroll a loop if it doesn't end with a
526 JUMP_INSN. There would need to be a mechanism that recognizes
527 this case, and then inserts a jump after each loop body, which
528 jumps to after the last loop body. */
529 if (loop_dump_stream
)
530 fprintf (loop_dump_stream
,
531 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
537 /* Normal case: Must copy the compare and branch instructions at the
540 if (GET_CODE (last_loop_insn
) == BARRIER
)
542 /* Loop ends with an unconditional jump and a barrier.
543 Handle this like above, don't copy jump and barrier.
544 This is not strictly necessary, but doing so prevents generating
545 unconditional jumps to an immediately following label.
547 This will be corrected below if the target of this jump is
548 not the start_label. */
550 insert_before
= PREV_INSN (last_loop_insn
);
551 copy_end
= PREV_INSN (insert_before
);
553 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
555 /* Set insert_before to immediately after the JUMP_INSN, so that
556 NOTEs at the end of the loop will be correctly handled by
558 insert_before
= NEXT_INSN (last_loop_insn
);
559 copy_end
= last_loop_insn
;
563 /* We currently can't unroll a loop if it doesn't end with a
564 JUMP_INSN. There would need to be a mechanism that recognizes
565 this case, and then inserts a jump after each loop body, which
566 jumps to after the last loop body. */
567 if (loop_dump_stream
)
568 fprintf (loop_dump_stream
,
569 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
573 /* If copying exit test branches because they can not be eliminated,
574 then must convert the fall through case of the branch to a jump past
575 the end of the loop. Create a label to emit after the loop and save
576 it for later use. Do not use the label after the loop, if any, since
577 it might be used by insns outside the loop, or there might be insns
578 added before it later by final_[bg]iv_value which must be after
579 the real exit label. */
580 exit_label
= gen_label_rtx ();
583 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
584 insn
= NEXT_INSN (insn
);
586 if (GET_CODE (insn
) == JUMP_INSN
)
588 /* The loop starts with a jump down to the exit condition test.
589 Start copying the loop after the barrier following this
591 copy_start
= NEXT_INSN (insn
);
593 /* Splitting induction variables doesn't work when the loop is
594 entered via a jump to the bottom, because then we end up doing
595 a comparison against a new register for a split variable, but
596 we did not execute the set insn for the new register because
597 it was skipped over. */
598 splitting_not_safe
= 1;
599 if (loop_dump_stream
)
600 fprintf (loop_dump_stream
,
601 "Splitting not safe, because loop not entered at top.\n");
604 copy_start
= loop_start
;
607 /* This should always be the first label in the loop. */
608 start_label
= NEXT_INSN (copy_start
);
609 /* There may be a line number note and/or a loop continue note here. */
610 while (GET_CODE (start_label
) == NOTE
)
611 start_label
= NEXT_INSN (start_label
);
612 if (GET_CODE (start_label
) != CODE_LABEL
)
614 /* This can happen as a result of jump threading. If the first insns in
615 the loop test the same condition as the loop's backward jump, or the
616 opposite condition, then the backward jump will be modified to point
617 to elsewhere, and the loop's start label is deleted.
619 This case currently can not be handled by the loop unrolling code. */
621 if (loop_dump_stream
)
622 fprintf (loop_dump_stream
,
623 "Unrolling failure: unknown insns between BEG note and loop label.\n");
626 if (LABEL_NAME (start_label
))
628 /* The jump optimization pass must have combined the original start label
629 with a named label for a goto. We can't unroll this case because
630 jumps which go to the named label must be handled differently than
631 jumps to the loop start, and it is impossible to differentiate them
633 if (loop_dump_stream
)
634 fprintf (loop_dump_stream
,
635 "Unrolling failure: loop start label is gone\n");
639 if (unroll_type
== UNROLL_NAIVE
640 && GET_CODE (last_loop_insn
) == BARRIER
641 && GET_CODE (PREV_INSN (last_loop_insn
)) == JUMP_INSN
642 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
644 /* In this case, we must copy the jump and barrier, because they will
645 not be converted to jumps to an immediately following label. */
647 insert_before
= NEXT_INSN (last_loop_insn
);
648 copy_end
= last_loop_insn
;
651 if (unroll_type
== UNROLL_NAIVE
652 && GET_CODE (last_loop_insn
) == JUMP_INSN
653 && start_label
!= JUMP_LABEL (last_loop_insn
))
655 /* ??? The loop ends with a conditional branch that does not branch back
656 to the loop start label. In this case, we must emit an unconditional
657 branch to the loop exit after emitting the final branch.
658 copy_loop_body does not have support for this currently, so we
659 give up. It doesn't seem worthwhile to unroll anyways since
660 unrolling would increase the number of branch instructions
662 if (loop_dump_stream
)
663 fprintf (loop_dump_stream
,
664 "Unrolling failure: final conditional branch not to loop start\n");
668 /* Allocate a translation table for the labels and insn numbers.
669 They will be filled in as we copy the insns in the loop. */
671 max_labelno
= max_label_num ();
672 max_insnno
= get_max_uid ();
674 /* Various paths through the unroll code may reach the "egress" label
675 without initializing fields within the map structure.
677 To be safe, we use xcalloc to zero the memory. */
678 map
= (struct inline_remap
*) xcalloc (1, sizeof (struct inline_remap
));
680 /* Allocate the label map. */
684 map
->label_map
= (rtx
*) xcalloc (max_labelno
, sizeof (rtx
));
685 local_label
= (char *) xcalloc (max_labelno
, sizeof (char));
688 /* Search the loop and mark all local labels, i.e. the ones which have to
689 be distinct labels when copied. For all labels which might be
690 non-local, set their label_map entries to point to themselves.
691 If they happen to be local their label_map entries will be overwritten
692 before the loop body is copied. The label_map entries for local labels
693 will be set to a different value each time the loop body is copied. */
695 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
699 if (GET_CODE (insn
) == CODE_LABEL
)
700 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
701 else if (GET_CODE (insn
) == JUMP_INSN
)
703 if (JUMP_LABEL (insn
))
704 set_label_in_map (map
,
705 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)),
707 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
708 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
710 rtx pat
= PATTERN (insn
);
711 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
712 int len
= XVECLEN (pat
, diff_vec_p
);
715 for (i
= 0; i
< len
; i
++)
717 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
718 set_label_in_map (map
, CODE_LABEL_NUMBER (label
), label
);
722 if ((note
= find_reg_note (insn
, REG_LABEL
, NULL_RTX
)))
723 set_label_in_map (map
, CODE_LABEL_NUMBER (XEXP (note
, 0)),
727 /* Allocate space for the insn map. */
729 map
->insn_map
= (rtx
*) xmalloc (max_insnno
* sizeof (rtx
));
731 /* Set this to zero, to indicate that we are doing loop unrolling,
732 not function inlining. */
733 map
->inline_target
= 0;
735 /* The register and constant maps depend on the number of registers
736 present, so the final maps can't be created until after
737 find_splittable_regs is called. However, they are needed for
738 preconditioning, so we create temporary maps when preconditioning
741 /* The preconditioning code may allocate two new pseudo registers. */
742 maxregnum
= max_reg_num ();
744 /* local_regno is only valid for regnos < max_local_regnum. */
745 max_local_regnum
= maxregnum
;
747 /* Allocate and zero out the splittable_regs and addr_combined_regs
748 arrays. These must be zeroed here because they will be used if
749 loop preconditioning is performed, and must be zero for that case.
751 It is safe to do this here, since the extra registers created by the
752 preconditioning code and find_splittable_regs will never be used
753 to access the splittable_regs[] and addr_combined_regs[] arrays. */
755 splittable_regs
= (rtx
*) xcalloc (maxregnum
, sizeof (rtx
));
756 splittable_regs_updates
= (int *) xcalloc (maxregnum
, sizeof (int));
758 = (struct induction
**) xcalloc (maxregnum
, sizeof (struct induction
*));
759 local_regno
= (char *) xcalloc (maxregnum
, sizeof (char));
761 /* Mark all local registers, i.e. the ones which are referenced only
763 if (INSN_UID (copy_end
) < max_uid_for_loop
)
765 int copy_start_luid
= INSN_LUID (copy_start
);
766 int copy_end_luid
= INSN_LUID (copy_end
);
768 /* If a register is used in the jump insn, we must not duplicate it
769 since it will also be used outside the loop. */
770 if (GET_CODE (copy_end
) == JUMP_INSN
)
773 /* If we have a target that uses cc0, then we also must not duplicate
774 the insn that sets cc0 before the jump insn, if one is present. */
776 if (GET_CODE (copy_end
) == JUMP_INSN
777 && sets_cc0_p (PREV_INSN (copy_end
)))
781 /* If copy_start points to the NOTE that starts the loop, then we must
782 use the next luid, because invariant pseudo-regs moved out of the loop
783 have their lifetimes modified to start here, but they are not safe
785 if (copy_start
== loop_start
)
788 /* If a pseudo's lifetime is entirely contained within this loop, then we
789 can use a different pseudo in each unrolled copy of the loop. This
790 results in better code. */
791 /* We must limit the generic test to max_reg_before_loop, because only
792 these pseudo registers have valid regno_first_uid info. */
793 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_reg_before_loop
; ++r
)
794 if (REGNO_FIRST_UID (r
) > 0 && REGNO_FIRST_UID (r
) < max_uid_for_loop
795 && REGNO_FIRST_LUID (r
) >= copy_start_luid
796 && REGNO_LAST_UID (r
) > 0 && REGNO_LAST_UID (r
) < max_uid_for_loop
797 && REGNO_LAST_LUID (r
) <= copy_end_luid
)
799 /* However, we must also check for loop-carried dependencies.
800 If the value the pseudo has at the end of iteration X is
801 used by iteration X+1, then we can not use a different pseudo
802 for each unrolled copy of the loop. */
803 /* A pseudo is safe if regno_first_uid is a set, and this
804 set dominates all instructions from regno_first_uid to
806 /* ??? This check is simplistic. We would get better code if
807 this check was more sophisticated. */
808 if (set_dominates_use (r
, REGNO_FIRST_UID (r
), REGNO_LAST_UID (r
),
809 copy_start
, copy_end
))
812 if (loop_dump_stream
)
815 fprintf (loop_dump_stream
, "Marked reg %d as local\n", r
);
817 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
823 /* If this loop requires exit tests when unrolled, check to see if we
824 can precondition the loop so as to make the exit tests unnecessary.
825 Just like variable splitting, this is not safe if the loop is entered
826 via a jump to the bottom. Also, can not do this if no strength
827 reduce info, because precondition_loop_p uses this info. */
829 /* Must copy the loop body for preconditioning before the following
830 find_splittable_regs call since that will emit insns which need to
831 be after the preconditioned loop copies, but immediately before the
832 unrolled loop copies. */
834 /* Also, it is not safe to split induction variables for the preconditioned
835 copies of the loop body. If we split induction variables, then the code
836 assumes that each induction variable can be represented as a function
837 of its initial value and the loop iteration number. This is not true
838 in this case, because the last preconditioned copy of the loop body
839 could be any iteration from the first up to the `unroll_number-1'th,
840 depending on the initial value of the iteration variable. Therefore
841 we can not split induction variables here, because we can not calculate
842 their value. Hence, this code must occur before find_splittable_regs
845 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
847 rtx initial_value
, final_value
, increment
;
848 enum machine_mode mode
;
850 if (precondition_loop_p (loop
,
851 &initial_value
, &final_value
, &increment
,
856 int abs_inc
, neg_inc
;
857 enum rtx_code cc
= loop_info
->comparison_code
;
858 int less_p
= (cc
== LE
|| cc
== LEU
|| cc
== LT
|| cc
== LTU
);
859 int unsigned_p
= (cc
== LEU
|| cc
== GEU
|| cc
== LTU
|| cc
== GTU
);
861 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
863 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
, maxregnum
,
864 "unroll_loop_precondition");
865 global_const_equiv_varray
= map
->const_equiv_varray
;
867 init_reg_map (map
, maxregnum
);
869 /* Limit loop unrolling to 4, since this will make 7 copies of
871 if (unroll_number
> 4)
874 /* Save the absolute value of the increment, and also whether or
875 not it is negative. */
877 abs_inc
= INTVAL (increment
);
886 /* We must copy the final and initial values here to avoid
887 improperly shared rtl. */
888 final_value
= copy_rtx (final_value
);
889 initial_value
= copy_rtx (initial_value
);
891 /* Final value may have form of (PLUS val1 const1_rtx). We need
892 to convert it into general operand, so compute the real value. */
894 final_value
= force_operand (final_value
, NULL_RTX
);
895 if (!nonmemory_operand (final_value
, VOIDmode
))
896 final_value
= force_reg (mode
, final_value
);
898 /* Calculate the difference between the final and initial values.
899 Final value may be a (plus (reg x) (const_int 1)) rtx.
901 We have to deal with for (i = 0; --i < 6;) type loops.
902 For such loops the real final value is the first time the
903 loop variable overflows, so the diff we calculate is the
904 distance from the overflow value. This is 0 or ~0 for
905 unsigned loops depending on the direction, or INT_MAX,
906 INT_MAX+1 for signed loops. We really do not need the
907 exact value, since we are only interested in the diff
908 modulo the increment, and the increment is a power of 2,
909 so we can pretend that the overflow value is 0/~0. */
911 if (cc
== NE
|| less_p
!= neg_inc
)
912 diff
= simplify_gen_binary (MINUS
, mode
, final_value
,
915 diff
= simplify_gen_unary (neg_inc
? NOT
: NEG
, mode
,
916 initial_value
, mode
);
917 diff
= force_operand (diff
, NULL_RTX
);
919 /* Now calculate (diff % (unroll * abs (increment))) by using an
921 diff
= simplify_gen_binary (AND
, mode
, diff
,
922 GEN_INT (unroll_number
*abs_inc
- 1));
923 diff
= force_operand (diff
, NULL_RTX
);
925 /* Now emit a sequence of branches to jump to the proper precond
928 labels
= (rtx
*) xmalloc (sizeof (rtx
) * unroll_number
);
929 for (i
= 0; i
< unroll_number
; i
++)
930 labels
[i
] = gen_label_rtx ();
932 /* Check for the case where the initial value is greater than or
933 equal to the final value. In that case, we want to execute
934 exactly one loop iteration. The code below will fail for this
935 case. This check does not apply if the loop has a NE
936 comparison at the end. */
940 rtx incremented_initval
;
941 enum rtx_code cmp_code
;
944 = simplify_gen_binary (PLUS
, mode
, initial_value
, increment
);
946 = force_operand (incremented_initval
, NULL_RTX
);
949 ? (unsigned_p
? GEU
: GE
)
950 : (unsigned_p
? LEU
: LE
));
952 insn
= simplify_cmp_and_jump_insns (cmp_code
, mode
,
954 final_value
, labels
[1]);
956 predict_insn_def (insn
, PRED_LOOP_CONDITION
, TAKEN
);
959 /* Assuming the unroll_number is 4, and the increment is 2, then
960 for a negative increment: for a positive increment:
961 diff = 0,1 precond 0 diff = 0,7 precond 0
962 diff = 2,3 precond 3 diff = 1,2 precond 1
963 diff = 4,5 precond 2 diff = 3,4 precond 2
964 diff = 6,7 precond 1 diff = 5,6 precond 3 */
966 /* We only need to emit (unroll_number - 1) branches here, the
967 last case just falls through to the following code. */
969 /* ??? This would give better code if we emitted a tree of branches
970 instead of the current linear list of branches. */
972 for (i
= 0; i
< unroll_number
- 1; i
++)
975 enum rtx_code cmp_code
;
977 /* For negative increments, must invert the constant compared
978 against, except when comparing against zero. */
986 cmp_const
= unroll_number
- i
;
995 insn
= simplify_cmp_and_jump_insns (cmp_code
, mode
, diff
,
996 GEN_INT (abs_inc
*cmp_const
),
999 predict_insn (insn
, PRED_LOOP_PRECONDITIONING
,
1000 REG_BR_PROB_BASE
/ (unroll_number
- i
));
1003 /* If the increment is greater than one, then we need another branch,
1004 to handle other cases equivalent to 0. */
1006 /* ??? This should be merged into the code above somehow to help
1007 simplify the code here, and reduce the number of branches emitted.
1008 For the negative increment case, the branch here could easily
1009 be merged with the `0' case branch above. For the positive
1010 increment case, it is not clear how this can be simplified. */
1015 enum rtx_code cmp_code
;
1019 cmp_const
= abs_inc
- 1;
1024 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
1028 simplify_cmp_and_jump_insns (cmp_code
, mode
, diff
,
1029 GEN_INT (cmp_const
), labels
[0]);
1032 sequence
= get_insns ();
1034 loop_insn_hoist (loop
, sequence
);
1036 /* Only the last copy of the loop body here needs the exit
1037 test, so set copy_end to exclude the compare/branch here,
1038 and then reset it inside the loop when get to the last
1041 if (GET_CODE (last_loop_insn
) == BARRIER
)
1042 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1043 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1045 copy_end
= PREV_INSN (last_loop_insn
);
1047 /* The immediately preceding insn may be a compare which
1048 we do not want to copy. */
1049 if (sets_cc0_p (PREV_INSN (copy_end
)))
1050 copy_end
= PREV_INSN (copy_end
);
1056 for (i
= 1; i
< unroll_number
; i
++)
1058 emit_label_after (labels
[unroll_number
- i
],
1059 PREV_INSN (loop_start
));
1061 memset ((char *) map
->insn_map
, 0, max_insnno
* sizeof (rtx
));
1062 memset ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0),
1063 0, (VARRAY_SIZE (map
->const_equiv_varray
)
1064 * sizeof (struct const_equiv_data
)));
1067 for (j
= 0; j
< max_labelno
; j
++)
1069 set_label_in_map (map
, j
, gen_label_rtx ());
1071 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1075 = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1076 record_base_value (REGNO (map
->reg_map
[r
]),
1077 regno_reg_rtx
[r
], 0);
1079 /* The last copy needs the compare/branch insns at the end,
1080 so reset copy_end here if the loop ends with a conditional
1083 if (i
== unroll_number
- 1)
1085 if (GET_CODE (last_loop_insn
) == BARRIER
)
1086 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1088 copy_end
= last_loop_insn
;
1091 /* None of the copies are the `last_iteration', so just
1092 pass zero for that parameter. */
1093 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
, 0,
1094 unroll_type
, start_label
, loop_end
,
1095 loop_start
, copy_end
);
1097 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1099 if (GET_CODE (last_loop_insn
) == BARRIER
)
1101 insert_before
= PREV_INSN (last_loop_insn
);
1102 copy_end
= PREV_INSN (insert_before
);
1106 insert_before
= last_loop_insn
;
1108 /* The instruction immediately before the JUMP_INSN may
1109 be a compare instruction which we do not want to copy
1111 if (sets_cc0_p (PREV_INSN (insert_before
)))
1112 insert_before
= PREV_INSN (insert_before
);
1114 copy_end
= PREV_INSN (insert_before
);
1117 /* Set unroll type to MODULO now. */
1118 unroll_type
= UNROLL_MODULO
;
1119 loop_preconditioned
= 1;
1126 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1127 the loop unless all loops are being unrolled. */
1128 if (unroll_type
== UNROLL_NAIVE
&& ! flag_old_unroll_all_loops
)
1130 if (loop_dump_stream
)
1131 fprintf (loop_dump_stream
,
1132 "Unrolling failure: Naive unrolling not being done.\n");
1136 /* At this point, we are guaranteed to unroll the loop. */
1138 /* Keep track of the unroll factor for the loop. */
1139 loop_info
->unroll_number
= unroll_number
;
1141 /* And whether the loop has been preconditioned. */
1142 loop_info
->preconditioned
= loop_preconditioned
;
1144 /* Remember whether it was preconditioned for the second loop pass. */
1145 NOTE_PRECONDITIONED (loop
->end
) = loop_preconditioned
;
1147 /* For each biv and giv, determine whether it can be safely split into
1148 a different variable for each unrolled copy of the loop body.
1149 We precalculate and save this info here, since computing it is
1152 Do this before deleting any instructions from the loop, so that
1153 back_branch_in_range_p will work correctly. */
1155 if (splitting_not_safe
)
1158 temp
= find_splittable_regs (loop
, unroll_type
, unroll_number
);
1160 /* find_splittable_regs may have created some new registers, so must
1161 reallocate the reg_map with the new larger size, and must realloc
1162 the constant maps also. */
1164 maxregnum
= max_reg_num ();
1165 map
->reg_map
= (rtx
*) xmalloc (maxregnum
* sizeof (rtx
));
1167 init_reg_map (map
, maxregnum
);
1169 if (map
->const_equiv_varray
== 0)
1170 VARRAY_CONST_EQUIV_INIT (map
->const_equiv_varray
,
1171 maxregnum
+ temp
* unroll_number
* 2,
1173 global_const_equiv_varray
= map
->const_equiv_varray
;
1175 /* Search the list of bivs and givs to find ones which need to be remapped
1176 when split, and set their reg_map entry appropriately. */
1178 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
1180 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1181 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1183 /* Currently, non-reduced/final-value givs are never split. */
1184 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1185 if (REGNO (v
->src_reg
) != bl
->regno
)
1186 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1190 /* Use our current register alignment and pointer flags. */
1191 map
->regno_pointer_align
= cfun
->emit
->regno_pointer_align
;
1192 map
->x_regno_reg_rtx
= cfun
->emit
->x_regno_reg_rtx
;
1194 /* If the loop is being partially unrolled, and the iteration variables
1195 are being split, and are being renamed for the split, then must fix up
1196 the compare/jump instruction at the end of the loop to refer to the new
1197 registers. This compare isn't copied, so the registers used in it
1198 will never be replaced if it isn't done here. */
1200 if (unroll_type
== UNROLL_MODULO
)
1202 insn
= NEXT_INSN (copy_end
);
1203 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1204 PATTERN (insn
) = remap_split_bivs (loop
, PATTERN (insn
));
1207 /* For unroll_number times, make a copy of each instruction
1208 between copy_start and copy_end, and insert these new instructions
1209 before the end of the loop. */
1211 for (i
= 0; i
< unroll_number
; i
++)
1213 memset ((char *) map
->insn_map
, 0, max_insnno
* sizeof (rtx
));
1214 memset ((char *) &VARRAY_CONST_EQUIV (map
->const_equiv_varray
, 0), 0,
1215 VARRAY_SIZE (map
->const_equiv_varray
) * sizeof (struct const_equiv_data
));
1218 for (j
= 0; j
< max_labelno
; j
++)
1220 set_label_in_map (map
, j
, gen_label_rtx ());
1222 for (r
= FIRST_PSEUDO_REGISTER
; r
< max_local_regnum
; r
++)
1225 map
->reg_map
[r
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[r
]));
1226 record_base_value (REGNO (map
->reg_map
[r
]),
1227 regno_reg_rtx
[r
], 0);
1230 /* If loop starts with a branch to the test, then fix it so that
1231 it points to the test of the first unrolled copy of the loop. */
1232 if (i
== 0 && loop_start
!= copy_start
)
1234 insn
= PREV_INSN (copy_start
);
1235 pattern
= PATTERN (insn
);
1237 tem
= get_label_from_map (map
,
1239 (XEXP (SET_SRC (pattern
), 0)));
1240 SET_SRC (pattern
) = gen_rtx_LABEL_REF (VOIDmode
, tem
);
1242 /* Set the jump label so that it can be used by later loop unrolling
1244 JUMP_LABEL (insn
) = tem
;
1245 LABEL_NUSES (tem
)++;
1248 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
,
1249 i
== unroll_number
- 1, unroll_type
, start_label
,
1250 loop_end
, insert_before
, insert_before
);
1253 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1254 insn to be deleted. This prevents any runaway delete_insn call from
1255 more insns that it should, as it always stops at a CODE_LABEL. */
1257 /* Delete the compare and branch at the end of the loop if completely
1258 unrolling the loop. Deleting the backward branch at the end also
1259 deletes the code label at the start of the loop. This is done at
1260 the very end to avoid problems with back_branch_in_range_p. */
1262 if (unroll_type
== UNROLL_COMPLETELY
)
1263 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1265 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1267 /* Delete all of the original loop instructions. Don't delete the
1268 LOOP_BEG note, or the first code label in the loop. */
1270 insn
= NEXT_INSN (copy_start
);
1271 while (insn
!= safety_label
)
1273 /* ??? Don't delete named code labels. They will be deleted when the
1274 jump that references them is deleted. Otherwise, we end up deleting
1275 them twice, which causes them to completely disappear instead of turn
1276 into NOTE_INSN_DELETED_LABEL notes. This in turn causes aborts in
1277 dwarfout.c/dwarf2out.c. We could perhaps fix the dwarf*out.c files
1278 to handle deleted labels instead. Or perhaps fix DECL_RTL of the
1279 associated LABEL_DECL to point to one of the new label instances. */
1280 /* ??? Likewise, we can't delete a NOTE_INSN_DELETED_LABEL note. */
1281 if (insn
!= start_label
1282 && ! (GET_CODE (insn
) == CODE_LABEL
&& LABEL_NAME (insn
))
1283 && ! (GET_CODE (insn
) == NOTE
1284 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_DELETED_LABEL
))
1285 insn
= delete_related_insns (insn
);
1287 insn
= NEXT_INSN (insn
);
1290 /* Can now delete the 'safety' label emitted to protect us from runaway
1291 delete_related_insns calls. */
1292 if (INSN_DELETED_P (safety_label
))
1294 delete_related_insns (safety_label
);
1296 /* If exit_label exists, emit it after the loop. Doing the emit here
1297 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1298 This is needed so that mostly_true_jump in reorg.c will treat jumps
1299 to this loop end label correctly, i.e. predict that they are usually
1302 emit_label_after (exit_label
, loop_end
);
1305 if (unroll_type
== UNROLL_COMPLETELY
)
1307 /* Remove the loop notes since this is no longer a loop. */
1309 delete_related_insns (loop
->vtop
);
1311 delete_related_insns (loop
->cont
);
1313 delete_related_insns (loop_start
);
1315 delete_related_insns (loop_end
);
1318 if (map
->const_equiv_varray
)
1319 VARRAY_FREE (map
->const_equiv_varray
);
1322 free (map
->label_map
);
1325 free (map
->insn_map
);
1326 free (splittable_regs
);
1327 free (splittable_regs_updates
);
1328 free (addr_combined_regs
);
1331 free (map
->reg_map
);
1335 /* A helper function for unroll_loop. Emit a compare and branch to
1336 satisfy (CMP OP1 OP2), but pass this through the simplifier first.
1337 If the branch turned out to be conditional, return it, otherwise
1341 simplify_cmp_and_jump_insns (code
, mode
, op0
, op1
, label
)
1343 enum machine_mode mode
;
1344 rtx op0
, op1
, label
;
1348 t
= simplify_relational_operation (code
, mode
, op0
, op1
);
1351 enum rtx_code scode
= signed_condition (code
);
1352 emit_cmp_and_jump_insns (op0
, op1
, scode
, NULL_RTX
, mode
,
1353 code
!= scode
, label
);
1354 insn
= get_last_insn ();
1356 JUMP_LABEL (insn
) = label
;
1357 LABEL_NUSES (label
) += 1;
1361 else if (t
== const_true_rtx
)
1363 insn
= emit_jump_insn (gen_jump (label
));
1365 JUMP_LABEL (insn
) = label
;
1366 LABEL_NUSES (label
) += 1;
1372 /* Return true if the loop can be safely, and profitably, preconditioned
1373 so that the unrolled copies of the loop body don't need exit tests.
1375 This only works if final_value, initial_value and increment can be
1376 determined, and if increment is a constant power of 2.
1377 If increment is not a power of 2, then the preconditioning modulo
1378 operation would require a real modulo instead of a boolean AND, and this
1379 is not considered `profitable'. */
1381 /* ??? If the loop is known to be executed very many times, or the machine
1382 has a very cheap divide instruction, then preconditioning is a win even
1383 when the increment is not a power of 2. Use RTX_COST to compute
1384 whether divide is cheap.
1385 ??? A divide by constant doesn't actually need a divide, look at
1386 expand_divmod. The reduced cost of this optimized modulo is not
1387 reflected in RTX_COST. */
1390 precondition_loop_p (loop
, initial_value
, final_value
, increment
, mode
)
1391 const struct loop
*loop
;
1392 rtx
*initial_value
, *final_value
, *increment
;
1393 enum machine_mode
*mode
;
1395 rtx loop_start
= loop
->start
;
1396 struct loop_info
*loop_info
= LOOP_INFO (loop
);
1398 if (loop_info
->n_iterations
> 0)
1400 if (INTVAL (loop_info
->increment
) > 0)
1402 *initial_value
= const0_rtx
;
1403 *increment
= const1_rtx
;
1404 *final_value
= GEN_INT (loop_info
->n_iterations
);
1408 *initial_value
= GEN_INT (loop_info
->n_iterations
);
1409 *increment
= constm1_rtx
;
1410 *final_value
= const0_rtx
;
1414 if (loop_dump_stream
)
1415 fprintf (loop_dump_stream
,
1416 "Preconditioning: Success, number of iterations known, "
1417 HOST_WIDE_INT_PRINT_DEC
".\n",
1418 loop_info
->n_iterations
);
1422 if (loop_info
->iteration_var
== 0)
1424 if (loop_dump_stream
)
1425 fprintf (loop_dump_stream
,
1426 "Preconditioning: Could not find iteration variable.\n");
1429 else if (loop_info
->initial_value
== 0)
1431 if (loop_dump_stream
)
1432 fprintf (loop_dump_stream
,
1433 "Preconditioning: Could not find initial value.\n");
1436 else if (loop_info
->increment
== 0)
1438 if (loop_dump_stream
)
1439 fprintf (loop_dump_stream
,
1440 "Preconditioning: Could not find increment value.\n");
1443 else if (GET_CODE (loop_info
->increment
) != CONST_INT
)
1445 if (loop_dump_stream
)
1446 fprintf (loop_dump_stream
,
1447 "Preconditioning: Increment not a constant.\n");
1450 else if ((exact_log2 (INTVAL (loop_info
->increment
)) < 0)
1451 && (exact_log2 (-INTVAL (loop_info
->increment
)) < 0))
1453 if (loop_dump_stream
)
1454 fprintf (loop_dump_stream
,
1455 "Preconditioning: Increment not a constant power of 2.\n");
1459 /* Unsigned_compare and compare_dir can be ignored here, since they do
1460 not matter for preconditioning. */
1462 if (loop_info
->final_value
== 0)
1464 if (loop_dump_stream
)
1465 fprintf (loop_dump_stream
,
1466 "Preconditioning: EQ comparison loop.\n");
1470 /* Must ensure that final_value is invariant, so call
1471 loop_invariant_p to check. Before doing so, must check regno
1472 against max_reg_before_loop to make sure that the register is in
1473 the range covered by loop_invariant_p. If it isn't, then it is
1474 most likely a biv/giv which by definition are not invariant. */
1475 if ((GET_CODE (loop_info
->final_value
) == REG
1476 && REGNO (loop_info
->final_value
) >= max_reg_before_loop
)
1477 || (GET_CODE (loop_info
->final_value
) == PLUS
1478 && REGNO (XEXP (loop_info
->final_value
, 0)) >= max_reg_before_loop
)
1479 || ! loop_invariant_p (loop
, loop_info
->final_value
))
1481 if (loop_dump_stream
)
1482 fprintf (loop_dump_stream
,
1483 "Preconditioning: Final value not invariant.\n");
1487 /* Fail for floating point values, since the caller of this function
1488 does not have code to deal with them. */
1489 if (GET_MODE_CLASS (GET_MODE (loop_info
->final_value
)) == MODE_FLOAT
1490 || GET_MODE_CLASS (GET_MODE (loop_info
->initial_value
)) == MODE_FLOAT
)
1492 if (loop_dump_stream
)
1493 fprintf (loop_dump_stream
,
1494 "Preconditioning: Floating point final or initial value.\n");
1498 /* Fail if loop_info->iteration_var is not live before loop_start,
1499 since we need to test its value in the preconditioning code. */
1501 if (REGNO_FIRST_LUID (REGNO (loop_info
->iteration_var
))
1502 > INSN_LUID (loop_start
))
1504 if (loop_dump_stream
)
1505 fprintf (loop_dump_stream
,
1506 "Preconditioning: Iteration var not live before loop start.\n");
1510 /* Note that loop_iterations biases the initial value for GIV iterators
1511 such as "while (i-- > 0)" so that we can calculate the number of
1512 iterations just like for BIV iterators.
1514 Also note that the absolute values of initial_value and
1515 final_value are unimportant as only their difference is used for
1516 calculating the number of loop iterations. */
1517 *initial_value
= loop_info
->initial_value
;
1518 *increment
= loop_info
->increment
;
1519 *final_value
= loop_info
->final_value
;
1521 /* Decide what mode to do these calculations in. Choose the larger
1522 of final_value's mode and initial_value's mode, or a full-word if
1523 both are constants. */
1524 *mode
= GET_MODE (*final_value
);
1525 if (*mode
== VOIDmode
)
1527 *mode
= GET_MODE (*initial_value
);
1528 if (*mode
== VOIDmode
)
1531 else if (*mode
!= GET_MODE (*initial_value
)
1532 && (GET_MODE_SIZE (*mode
)
1533 < GET_MODE_SIZE (GET_MODE (*initial_value
))))
1534 *mode
= GET_MODE (*initial_value
);
1537 if (loop_dump_stream
)
1538 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1542 /* All pseudo-registers must be mapped to themselves. Two hard registers
1543 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1544 REGNUM, to avoid function-inlining specific conversions of these
1545 registers. All other hard regs can not be mapped because they may be
1550 init_reg_map (map
, maxregnum
)
1551 struct inline_remap
*map
;
1556 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1557 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1558 /* Just clear the rest of the entries. */
1559 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1560 map
->reg_map
[i
] = 0;
1562 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1563 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1564 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1565 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1568 /* Strength-reduction will often emit code for optimized biv/givs which
1569 calculates their value in a temporary register, and then copies the result
1570 to the iv. This procedure reconstructs the pattern computing the iv;
1571 verifying that all operands are of the proper form.
1573 PATTERN must be the result of single_set.
1574 The return value is the amount that the giv is incremented by. */
1577 calculate_giv_inc (pattern
, src_insn
, regno
)
1578 rtx pattern
, src_insn
;
1582 rtx increment_total
= 0;
1586 /* Verify that we have an increment insn here. First check for a plus
1587 as the set source. */
1588 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1590 /* SR sometimes computes the new giv value in a temp, then copies it
1592 src_insn
= PREV_INSN (src_insn
);
1593 pattern
= single_set (src_insn
);
1594 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1597 /* The last insn emitted is not needed, so delete it to avoid confusing
1598 the second cse pass. This insn sets the giv unnecessarily. */
1599 delete_related_insns (get_last_insn ());
1602 /* Verify that we have a constant as the second operand of the plus. */
1603 increment
= XEXP (SET_SRC (pattern
), 1);
1604 if (GET_CODE (increment
) != CONST_INT
)
1606 /* SR sometimes puts the constant in a register, especially if it is
1607 too big to be an add immed operand. */
1608 increment
= find_last_value (increment
, &src_insn
, NULL_RTX
, 0);
1610 /* SR may have used LO_SUM to compute the constant if it is too large
1611 for a load immed operand. In this case, the constant is in operand
1612 one of the LO_SUM rtx. */
1613 if (GET_CODE (increment
) == LO_SUM
)
1614 increment
= XEXP (increment
, 1);
1616 /* Some ports store large constants in memory and add a REG_EQUAL
1617 note to the store insn. */
1618 else if (GET_CODE (increment
) == MEM
)
1620 rtx note
= find_reg_note (src_insn
, REG_EQUAL
, 0);
1622 increment
= XEXP (note
, 0);
1625 else if (GET_CODE (increment
) == IOR
1626 || GET_CODE (increment
) == PLUS
1627 || GET_CODE (increment
) == ASHIFT
1628 || GET_CODE (increment
) == LSHIFTRT
)
1630 /* The rs6000 port loads some constants with IOR.
1631 The alpha port loads some constants with ASHIFT and PLUS.
1632 The sparc64 port loads some constants with LSHIFTRT. */
1633 rtx second_part
= XEXP (increment
, 1);
1634 enum rtx_code code
= GET_CODE (increment
);
1636 increment
= find_last_value (XEXP (increment
, 0),
1637 &src_insn
, NULL_RTX
, 0);
1638 /* Don't need the last insn anymore. */
1639 delete_related_insns (get_last_insn ());
1641 if (GET_CODE (second_part
) != CONST_INT
1642 || GET_CODE (increment
) != CONST_INT
)
1646 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1647 else if (code
== PLUS
)
1648 increment
= GEN_INT (INTVAL (increment
) + INTVAL (second_part
));
1649 else if (code
== ASHIFT
)
1650 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1652 increment
= GEN_INT ((unsigned HOST_WIDE_INT
) INTVAL (increment
) >> INTVAL (second_part
));
1655 if (GET_CODE (increment
) != CONST_INT
)
1658 /* The insn loading the constant into a register is no longer needed,
1660 delete_related_insns (get_last_insn ());
1663 if (increment_total
)
1664 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1666 increment_total
= increment
;
1668 /* Check that the source register is the same as the register we expected
1669 to see as the source. If not, something is seriously wrong. */
1670 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1671 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1673 /* Some machines (e.g. the romp), may emit two add instructions for
1674 certain constants, so lets try looking for another add immediately
1675 before this one if we have only seen one add insn so far. */
1681 src_insn
= PREV_INSN (src_insn
);
1682 pattern
= single_set (src_insn
);
1684 delete_related_insns (get_last_insn ());
1692 return increment_total
;
1695 /* Copy REG_NOTES, except for insn references, because not all insn_map
1696 entries are valid yet. We do need to copy registers now though, because
1697 the reg_map entries can change during copying. */
1700 initial_reg_note_copy (notes
, map
)
1702 struct inline_remap
*map
;
1709 copy
= rtx_alloc (GET_CODE (notes
));
1710 PUT_REG_NOTE_KIND (copy
, REG_NOTE_KIND (notes
));
1712 if (GET_CODE (notes
) == EXPR_LIST
)
1713 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
, 0);
1714 else if (GET_CODE (notes
) == INSN_LIST
)
1715 /* Don't substitute for these yet. */
1716 XEXP (copy
, 0) = copy_rtx (XEXP (notes
, 0));
1720 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1725 /* Fixup insn references in copied REG_NOTES. */
1728 final_reg_note_copy (notesp
, map
)
1730 struct inline_remap
*map
;
1736 if (GET_CODE (note
) == INSN_LIST
)
1738 /* Sometimes, we have a REG_WAS_0 note that points to a
1739 deleted instruction. In that case, we can just delete the
1741 if (REG_NOTE_KIND (note
) == REG_WAS_0
)
1743 *notesp
= XEXP (note
, 1);
1748 rtx insn
= map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1750 /* If we failed to remap the note, something is awry.
1751 Allow REG_LABEL as it may reference label outside
1752 the unrolled loop. */
1755 if (REG_NOTE_KIND (note
) != REG_LABEL
)
1759 XEXP (note
, 0) = insn
;
1763 notesp
= &XEXP (note
, 1);
1767 /* Copy each instruction in the loop, substituting from map as appropriate.
1768 This is very similar to a loop in expand_inline_function. */
1771 copy_loop_body (loop
, copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1772 unroll_type
, start_label
, loop_end
, insert_before
,
1775 rtx copy_start
, copy_end
;
1776 struct inline_remap
*map
;
1779 enum unroll_types unroll_type
;
1780 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1782 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
1784 rtx set
, tem
, copy
= NULL_RTX
;
1785 int dest_reg_was_split
, i
;
1789 rtx final_label
= 0;
1790 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1792 /* If this isn't the last iteration, then map any references to the
1793 start_label to final_label. Final label will then be emitted immediately
1794 after the end of this loop body if it was ever used.
1796 If this is the last iteration, then map references to the start_label
1798 if (! last_iteration
)
1800 final_label
= gen_label_rtx ();
1801 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), final_label
);
1804 set_label_in_map (map
, CODE_LABEL_NUMBER (start_label
), start_label
);
1811 insn
= NEXT_INSN (insn
);
1813 map
->orig_asm_operands_vector
= 0;
1815 switch (GET_CODE (insn
))
1818 pattern
= PATTERN (insn
);
1822 /* Check to see if this is a giv that has been combined with
1823 some split address givs. (Combined in the sense that
1824 `combine_givs' in loop.c has put two givs in the same register.)
1825 In this case, we must search all givs based on the same biv to
1826 find the address givs. Then split the address givs.
1827 Do this before splitting the giv, since that may map the
1828 SET_DEST to a new register. */
1830 if ((set
= single_set (insn
))
1831 && GET_CODE (SET_DEST (set
)) == REG
1832 && addr_combined_regs
[REGNO (SET_DEST (set
))])
1834 struct iv_class
*bl
;
1835 struct induction
*v
, *tv
;
1836 unsigned int regno
= REGNO (SET_DEST (set
));
1838 v
= addr_combined_regs
[REGNO (SET_DEST (set
))];
1839 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
1841 /* Although the giv_inc amount is not needed here, we must call
1842 calculate_giv_inc here since it might try to delete the
1843 last insn emitted. If we wait until later to call it,
1844 we might accidentally delete insns generated immediately
1845 below by emit_unrolled_add. */
1847 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1849 /* Now find all address giv's that were combined with this
1851 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1852 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1856 /* If this DEST_ADDR giv was not split, then ignore it. */
1857 if (*tv
->location
!= tv
->dest_reg
)
1860 /* Scale this_giv_inc if the multiplicative factors of
1861 the two givs are different. */
1862 this_giv_inc
= INTVAL (giv_inc
);
1863 if (tv
->mult_val
!= v
->mult_val
)
1864 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1865 * INTVAL (tv
->mult_val
));
1867 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1868 *tv
->location
= tv
->dest_reg
;
1870 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1872 /* Must emit an insn to increment the split address
1873 giv. Add in the const_adjust field in case there
1874 was a constant eliminated from the address. */
1875 rtx value
, dest_reg
;
1877 /* tv->dest_reg will be either a bare register,
1878 or else a register plus a constant. */
1879 if (GET_CODE (tv
->dest_reg
) == REG
)
1880 dest_reg
= tv
->dest_reg
;
1882 dest_reg
= XEXP (tv
->dest_reg
, 0);
1884 /* Check for shared address givs, and avoid
1885 incrementing the shared pseudo reg more than
1887 if (! tv
->same_insn
&& ! tv
->shared
)
1889 /* tv->dest_reg may actually be a (PLUS (REG)
1890 (CONST)) here, so we must call plus_constant
1891 to add the const_adjust amount before calling
1892 emit_unrolled_add below. */
1893 value
= plus_constant (tv
->dest_reg
,
1896 if (GET_CODE (value
) == PLUS
)
1898 /* The constant could be too large for an add
1899 immediate, so can't directly emit an insn
1901 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1906 /* Reset the giv to be just the register again, in case
1907 it is used after the set we have just emitted.
1908 We must subtract the const_adjust factor added in
1910 tv
->dest_reg
= plus_constant (dest_reg
,
1912 *tv
->location
= tv
->dest_reg
;
1917 /* If this is a setting of a splittable variable, then determine
1918 how to split the variable, create a new set based on this split,
1919 and set up the reg_map so that later uses of the variable will
1920 use the new split variable. */
1922 dest_reg_was_split
= 0;
1924 if ((set
= single_set (insn
))
1925 && GET_CODE (SET_DEST (set
)) == REG
1926 && splittable_regs
[REGNO (SET_DEST (set
))])
1928 unsigned int regno
= REGNO (SET_DEST (set
));
1929 unsigned int src_regno
;
1931 dest_reg_was_split
= 1;
1933 giv_dest_reg
= SET_DEST (set
);
1934 giv_src_reg
= giv_dest_reg
;
1935 /* Compute the increment value for the giv, if it wasn't
1936 already computed above. */
1938 giv_inc
= calculate_giv_inc (set
, insn
, regno
);
1940 src_regno
= REGNO (giv_src_reg
);
1942 if (unroll_type
== UNROLL_COMPLETELY
)
1944 /* Completely unrolling the loop. Set the induction
1945 variable to a known constant value. */
1947 /* The value in splittable_regs may be an invariant
1948 value, so we must use plus_constant here. */
1949 splittable_regs
[regno
]
1950 = plus_constant (splittable_regs
[src_regno
],
1953 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1955 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1956 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1960 /* The splittable_regs value must be a REG or a
1961 CONST_INT, so put the entire value in the giv_src_reg
1963 giv_src_reg
= splittable_regs
[regno
];
1964 giv_inc
= const0_rtx
;
1969 /* Partially unrolling loop. Create a new pseudo
1970 register for the iteration variable, and set it to
1971 be a constant plus the original register. Except
1972 on the last iteration, when the result has to
1973 go back into the original iteration var register. */
1975 /* Handle bivs which must be mapped to a new register
1976 when split. This happens for bivs which need their
1977 final value set before loop entry. The new register
1978 for the biv was stored in the biv's first struct
1979 induction entry by find_splittable_regs. */
1981 if (regno
< ivs
->n_regs
1982 && REG_IV_TYPE (ivs
, regno
) == BASIC_INDUCT
)
1984 giv_src_reg
= REG_IV_CLASS (ivs
, regno
)->biv
->src_reg
;
1985 giv_dest_reg
= giv_src_reg
;
1989 /* If non-reduced/final-value givs were split, then
1990 this would have to remap those givs also. See
1991 find_splittable_regs. */
1994 splittable_regs
[regno
]
1995 = simplify_gen_binary (PLUS
, GET_MODE (giv_src_reg
),
1997 splittable_regs
[src_regno
]);
1998 giv_inc
= splittable_regs
[regno
];
2000 /* Now split the induction variable by changing the dest
2001 of this insn to a new register, and setting its
2002 reg_map entry to point to this new register.
2004 If this is the last iteration, and this is the last insn
2005 that will update the iv, then reuse the original dest,
2006 to ensure that the iv will have the proper value when
2007 the loop exits or repeats.
2009 Using splittable_regs_updates here like this is safe,
2010 because it can only be greater than one if all
2011 instructions modifying the iv are always executed in
2014 if (! last_iteration
2015 || (splittable_regs_updates
[regno
]-- != 1))
2017 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
2019 map
->reg_map
[regno
] = tem
;
2020 record_base_value (REGNO (tem
),
2021 giv_inc
== const0_rtx
2023 : gen_rtx_PLUS (GET_MODE (giv_src_reg
),
2024 giv_src_reg
, giv_inc
),
2028 map
->reg_map
[regno
] = giv_src_reg
;
2031 /* The constant being added could be too large for an add
2032 immediate, so can't directly emit an insn here. */
2033 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
2034 copy
= get_last_insn ();
2035 pattern
= PATTERN (copy
);
2039 pattern
= copy_rtx_and_substitute (pattern
, map
, 0);
2040 copy
= emit_insn (pattern
);
2042 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2043 INSN_LOCATOR (copy
) = INSN_LOCATOR (insn
);
2045 /* If there is a REG_EQUAL note present whose value
2046 is not loop invariant, then delete it, since it
2047 may cause problems with later optimization passes. */
2048 if ((tem
= find_reg_note (copy
, REG_EQUAL
, NULL_RTX
))
2049 && !loop_invariant_p (loop
, XEXP (tem
, 0)))
2050 remove_note (copy
, tem
);
2053 /* If this insn is setting CC0, it may need to look at
2054 the insn that uses CC0 to see what type of insn it is.
2055 In that case, the call to recog via validate_change will
2056 fail. So don't substitute constants here. Instead,
2057 do it when we emit the following insn.
2059 For example, see the pyr.md file. That machine has signed and
2060 unsigned compares. The compare patterns must check the
2061 following branch insn to see which what kind of compare to
2064 If the previous insn set CC0, substitute constants on it as
2066 if (sets_cc0_p (PATTERN (copy
)) != 0)
2071 try_constants (cc0_insn
, map
);
2073 try_constants (copy
, map
);
2076 try_constants (copy
, map
);
2079 /* Make split induction variable constants `permanent' since we
2080 know there are no backward branches across iteration variable
2081 settings which would invalidate this. */
2082 if (dest_reg_was_split
)
2084 int regno
= REGNO (SET_DEST (set
));
2086 if ((size_t) regno
< VARRAY_SIZE (map
->const_equiv_varray
)
2087 && (VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
2089 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, regno
).age
= -1;
2094 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2095 copy
= emit_jump_insn (pattern
);
2096 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2097 INSN_LOCATOR (copy
) = INSN_LOCATOR (insn
);
2099 if (JUMP_LABEL (insn
))
2101 JUMP_LABEL (copy
) = get_label_from_map (map
,
2103 (JUMP_LABEL (insn
)));
2104 LABEL_NUSES (JUMP_LABEL (copy
))++;
2106 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
2107 && ! last_iteration
)
2110 /* This is a branch to the beginning of the loop; this is the
2111 last insn being copied; and this is not the last iteration.
2112 In this case, we want to change the original fall through
2113 case to be a branch past the end of the loop, and the
2114 original jump label case to fall_through. */
2116 if (!invert_jump (copy
, exit_label
, 0))
2119 rtx lab
= gen_label_rtx ();
2120 /* Can't do it by reversing the jump (probably because we
2121 couldn't reverse the conditions), so emit a new
2122 jump_insn after COPY, and redirect the jump around
2124 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
2125 JUMP_LABEL (jmp
) = exit_label
;
2126 LABEL_NUSES (exit_label
)++;
2127 jmp
= emit_barrier_after (jmp
);
2128 emit_label_after (lab
, jmp
);
2129 LABEL_NUSES (lab
) = 0;
2130 if (!redirect_jump (copy
, lab
, 0))
2137 try_constants (cc0_insn
, map
);
2140 try_constants (copy
, map
);
2142 /* Set the jump label of COPY correctly to avoid problems with
2143 later passes of unroll_loop, if INSN had jump label set. */
2144 if (JUMP_LABEL (insn
))
2148 /* Can't use the label_map for every insn, since this may be
2149 the backward branch, and hence the label was not mapped. */
2150 if ((set
= single_set (copy
)))
2152 tem
= SET_SRC (set
);
2153 if (GET_CODE (tem
) == LABEL_REF
)
2154 label
= XEXP (tem
, 0);
2155 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
2157 if (XEXP (tem
, 1) != pc_rtx
)
2158 label
= XEXP (XEXP (tem
, 1), 0);
2160 label
= XEXP (XEXP (tem
, 2), 0);
2164 if (label
&& GET_CODE (label
) == CODE_LABEL
)
2165 JUMP_LABEL (copy
) = label
;
2168 /* An unrecognizable jump insn, probably the entry jump
2169 for a switch statement. This label must have been mapped,
2170 so just use the label_map to get the new jump label. */
2172 = get_label_from_map (map
,
2173 CODE_LABEL_NUMBER (JUMP_LABEL (insn
)));
2176 /* If this is a non-local jump, then must increase the label
2177 use count so that the label will not be deleted when the
2178 original jump is deleted. */
2179 LABEL_NUSES (JUMP_LABEL (copy
))++;
2181 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
2182 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
2184 rtx pat
= PATTERN (copy
);
2185 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
2186 int len
= XVECLEN (pat
, diff_vec_p
);
2189 for (i
= 0; i
< len
; i
++)
2190 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
2193 /* If this used to be a conditional jump insn but whose branch
2194 direction is now known, we must do something special. */
2195 if (any_condjump_p (insn
) && onlyjump_p (insn
) && map
->last_pc_value
)
2198 /* If the previous insn set cc0 for us, delete it. */
2199 if (only_sets_cc0_p (PREV_INSN (copy
)))
2200 delete_related_insns (PREV_INSN (copy
));
2203 /* If this is now a no-op, delete it. */
2204 if (map
->last_pc_value
== pc_rtx
)
2210 /* Otherwise, this is unconditional jump so we must put a
2211 BARRIER after it. We could do some dead code elimination
2212 here, but jump.c will do it just as well. */
2218 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
, 0);
2219 copy
= emit_call_insn (pattern
);
2220 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2221 INSN_LOCATOR (copy
) = INSN_LOCATOR (insn
);
2222 SIBLING_CALL_P (copy
) = SIBLING_CALL_P (insn
);
2223 CONST_OR_PURE_CALL_P (copy
) = CONST_OR_PURE_CALL_P (insn
);
2225 /* Because the USAGE information potentially contains objects other
2226 than hard registers, we need to copy it. */
2227 CALL_INSN_FUNCTION_USAGE (copy
)
2228 = copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
),
2233 try_constants (cc0_insn
, map
);
2236 try_constants (copy
, map
);
2238 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2239 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2240 VARRAY_CONST_EQUIV (map
->const_equiv_varray
, i
).rtx
= 0;
2244 /* If this is the loop start label, then we don't need to emit a
2245 copy of this label since no one will use it. */
2247 if (insn
!= start_label
)
2249 copy
= emit_label (get_label_from_map (map
,
2250 CODE_LABEL_NUMBER (insn
)));
2256 copy
= emit_barrier ();
2260 /* VTOP and CONT notes are valid only before the loop exit test.
2261 If placed anywhere else, loop may generate bad code. */
2262 /* BASIC_BLOCK notes exist to stabilize basic block structures with
2263 the associated rtl. We do not want to share the structure in
2266 if (NOTE_LINE_NUMBER (insn
) > 0)
2267 copy
= emit_line_note (NOTE_SOURCE_FILE (insn
),
2268 NOTE_LINE_NUMBER (insn
));
2269 else if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2270 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED_LABEL
2271 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2272 && ((NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2273 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2275 && unroll_type
!= UNROLL_COMPLETELY
)))
2277 copy
= emit_note (NULL
, NOTE_LINE_NUMBER (insn
));
2278 NOTE_DATA (copy
) = NOTE_DATA (insn
);
2288 map
->insn_map
[INSN_UID (insn
)] = copy
;
2290 while (insn
!= copy_end
);
2292 /* Now finish coping the REG_NOTES. */
2296 insn
= NEXT_INSN (insn
);
2297 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2298 || GET_CODE (insn
) == CALL_INSN
)
2299 && map
->insn_map
[INSN_UID (insn
)])
2300 final_reg_note_copy (®_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2302 while (insn
!= copy_end
);
2304 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2305 each of these notes here, since there may be some important ones, such as
2306 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2307 iteration, because the original notes won't be deleted.
2309 We can't use insert_before here, because when from preconditioning,
2310 insert_before points before the loop. We can't use copy_end, because
2311 there may be insns already inserted after it (which we don't want to
2312 copy) when not from preconditioning code. */
2314 if (! last_iteration
)
2316 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2318 /* VTOP notes are valid only before the loop exit test.
2319 If placed anywhere else, loop may generate bad code.
2320 Although COPY_NOTES_FROM will be at most one or two (for cc0)
2321 instructions before the last insn in the loop, COPY_NOTES_FROM
2322 can be a NOTE_INSN_LOOP_CONT note if there is no VTOP note,
2323 as in a do .. while loop. */
2324 if (GET_CODE (insn
) != NOTE
)
2326 else if (NOTE_LINE_NUMBER (insn
) > 0)
2327 emit_line_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2328 else if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2329 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_BASIC_BLOCK
2330 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2331 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_CONT
)
2333 rtx copy
= emit_note (NULL
, NOTE_LINE_NUMBER (insn
));
2334 NOTE_DATA (copy
) = NOTE_DATA (insn
);
2339 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2340 emit_label (final_label
);
2344 loop_insn_emit_before (loop
, 0, insert_before
, tem
);
2347 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2348 emitted. This will correctly handle the case where the increment value
2349 won't fit in the immediate field of a PLUS insns. */
2352 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2353 rtx dest_reg
, src_reg
, increment
;
2357 result
= expand_simple_binop (GET_MODE (dest_reg
), PLUS
, src_reg
, increment
,
2358 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2360 if (dest_reg
!= result
)
2361 emit_move_insn (dest_reg
, result
);
2364 /* Searches the insns between INSN and LOOP->END. Returns 1 if there
2365 is a backward branch in that range that branches to somewhere between
2366 LOOP->START and INSN. Returns 0 otherwise. */
2368 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2369 In practice, this is not a problem, because this function is seldom called,
2370 and uses a negligible amount of CPU time on average. */
2373 back_branch_in_range_p (loop
, insn
)
2374 const struct loop
*loop
;
2377 rtx p
, q
, target_insn
;
2378 rtx loop_start
= loop
->start
;
2379 rtx loop_end
= loop
->end
;
2380 rtx orig_loop_end
= loop
->end
;
2382 /* Stop before we get to the backward branch at the end of the loop. */
2383 loop_end
= prev_nonnote_insn (loop_end
);
2384 if (GET_CODE (loop_end
) == BARRIER
)
2385 loop_end
= PREV_INSN (loop_end
);
2387 /* Check in case insn has been deleted, search forward for first non
2388 deleted insn following it. */
2389 while (INSN_DELETED_P (insn
))
2390 insn
= NEXT_INSN (insn
);
2392 /* Check for the case where insn is the last insn in the loop. Deal
2393 with the case where INSN was a deleted loop test insn, in which case
2394 it will now be the NOTE_LOOP_END. */
2395 if (insn
== loop_end
|| insn
== orig_loop_end
)
2398 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2400 if (GET_CODE (p
) == JUMP_INSN
)
2402 target_insn
= JUMP_LABEL (p
);
2404 /* Search from loop_start to insn, to see if one of them is
2405 the target_insn. We can't use INSN_LUID comparisons here,
2406 since insn may not have an LUID entry. */
2407 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2408 if (q
== target_insn
)
2416 /* Try to generate the simplest rtx for the expression
2417 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2421 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2422 rtx mult1
, mult2
, add1
;
2423 enum machine_mode mode
;
2428 /* The modes must all be the same. This should always be true. For now,
2429 check to make sure. */
2430 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2431 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2432 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2435 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2436 will be a constant. */
2437 if (GET_CODE (mult1
) == CONST_INT
)
2444 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2446 mult_res
= gen_rtx_MULT (mode
, mult1
, mult2
);
2448 /* Again, put the constant second. */
2449 if (GET_CODE (add1
) == CONST_INT
)
2456 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2458 result
= gen_rtx_PLUS (mode
, add1
, mult_res
);
2463 /* Searches the list of induction struct's for the biv BL, to try to calculate
2464 the total increment value for one iteration of the loop as a constant.
2466 Returns the increment value as an rtx, simplified as much as possible,
2467 if it can be calculated. Otherwise, returns 0. */
2470 biv_total_increment (bl
)
2471 const struct iv_class
*bl
;
2473 struct induction
*v
;
2476 /* For increment, must check every instruction that sets it. Each
2477 instruction must be executed only once each time through the loop.
2478 To verify this, we check that the insn is always executed, and that
2479 there are no backward branches after the insn that branch to before it.
2480 Also, the insn must have a mult_val of one (to make sure it really is
2483 result
= const0_rtx
;
2484 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2486 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2487 && ! v
->maybe_multiple
2488 && SCALAR_INT_MODE_P (v
->mode
))
2489 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2497 /* For each biv and giv, determine whether it can be safely split into
2498 a different variable for each unrolled copy of the loop body. If it
2499 is safe to split, then indicate that by saving some useful info
2500 in the splittable_regs array.
2502 If the loop is being completely unrolled, then splittable_regs will hold
2503 the current value of the induction variable while the loop is unrolled.
2504 It must be set to the initial value of the induction variable here.
2505 Otherwise, splittable_regs will hold the difference between the current
2506 value of the induction variable and the value the induction variable had
2507 at the top of the loop. It must be set to the value 0 here.
2509 Returns the total number of instructions that set registers that are
2512 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2513 constant values are unnecessary, since we can easily calculate increment
2514 values in this case even if nothing is constant. The increment value
2515 should not involve a multiply however. */
2517 /* ?? Even if the biv/giv increment values aren't constant, it may still
2518 be beneficial to split the variable if the loop is only unrolled a few
2519 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2522 find_splittable_regs (loop
, unroll_type
, unroll_number
)
2523 const struct loop
*loop
;
2524 enum unroll_types unroll_type
;
2527 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
2528 struct iv_class
*bl
;
2529 struct induction
*v
;
2531 rtx biv_final_value
;
2535 for (bl
= ivs
->list
; bl
; bl
= bl
->next
)
2537 /* Biv_total_increment must return a constant value,
2538 otherwise we can not calculate the split values. */
2540 increment
= biv_total_increment (bl
);
2541 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2544 /* The loop must be unrolled completely, or else have a known number
2545 of iterations and only one exit, or else the biv must be dead
2546 outside the loop, or else the final value must be known. Otherwise,
2547 it is unsafe to split the biv since it may not have the proper
2548 value on loop exit. */
2550 /* loop_number_exit_count is nonzero if the loop has an exit other than
2551 a fall through at the end. */
2554 biv_final_value
= 0;
2555 if (unroll_type
!= UNROLL_COMPLETELY
2556 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2557 && (REGNO_LAST_LUID (bl
->regno
) >= INSN_LUID (loop
->end
)
2559 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2560 || (REGNO_FIRST_LUID (bl
->regno
)
2561 < INSN_LUID (bl
->init_insn
))
2562 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2563 && ! (biv_final_value
= final_biv_value (loop
, bl
)))
2566 /* If any of the insns setting the BIV don't do so with a simple
2567 PLUS, we don't know how to split it. */
2568 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2569 if ((tem
= single_set (v
->insn
)) == 0
2570 || GET_CODE (SET_DEST (tem
)) != REG
2571 || REGNO (SET_DEST (tem
)) != bl
->regno
2572 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2575 /* If final value is nonzero, then must emit an instruction which sets
2576 the value of the biv to the proper value. This is done after
2577 handling all of the givs, since some of them may need to use the
2578 biv's value in their initialization code. */
2580 /* This biv is splittable. If completely unrolling the loop, save
2581 the biv's initial value. Otherwise, save the constant zero. */
2583 if (biv_splittable
== 1)
2585 if (unroll_type
== UNROLL_COMPLETELY
)
2587 /* If the initial value of the biv is itself (i.e. it is too
2588 complicated for strength_reduce to compute), or is a hard
2589 register, or it isn't invariant, then we must create a new
2590 pseudo reg to hold the initial value of the biv. */
2592 if (GET_CODE (bl
->initial_value
) == REG
2593 && (REGNO (bl
->initial_value
) == bl
->regno
2594 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2595 || ! loop_invariant_p (loop
, bl
->initial_value
)))
2597 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2599 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2600 loop_insn_hoist (loop
,
2601 gen_move_insn (tem
, bl
->biv
->src_reg
));
2603 if (loop_dump_stream
)
2604 fprintf (loop_dump_stream
,
2605 "Biv %d initial value remapped to %d.\n",
2606 bl
->regno
, REGNO (tem
));
2608 splittable_regs
[bl
->regno
] = tem
;
2611 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2614 splittable_regs
[bl
->regno
] = const0_rtx
;
2616 /* Save the number of instructions that modify the biv, so that
2617 we can treat the last one specially. */
2619 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2620 result
+= bl
->biv_count
;
2622 if (loop_dump_stream
)
2623 fprintf (loop_dump_stream
,
2624 "Biv %d safe to split.\n", bl
->regno
);
2627 /* Check every giv that depends on this biv to see whether it is
2628 splittable also. Even if the biv isn't splittable, givs which
2629 depend on it may be splittable if the biv is live outside the
2630 loop, and the givs aren't. */
2632 result
+= find_splittable_givs (loop
, bl
, unroll_type
, increment
,
2635 /* If final value is nonzero, then must emit an instruction which sets
2636 the value of the biv to the proper value. This is done after
2637 handling all of the givs, since some of them may need to use the
2638 biv's value in their initialization code. */
2639 if (biv_final_value
)
2641 /* If the loop has multiple exits, emit the insns before the
2642 loop to ensure that it will always be executed no matter
2643 how the loop exits. Otherwise emit the insn after the loop,
2644 since this is slightly more efficient. */
2645 if (! loop
->exit_count
)
2646 loop_insn_sink (loop
, gen_move_insn (bl
->biv
->src_reg
,
2650 /* Create a new register to hold the value of the biv, and then
2651 set the biv to its final value before the loop start. The biv
2652 is set to its final value before loop start to ensure that
2653 this insn will always be executed, no matter how the loop
2655 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2656 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2658 loop_insn_hoist (loop
, gen_move_insn (tem
, bl
->biv
->src_reg
));
2659 loop_insn_hoist (loop
, gen_move_insn (bl
->biv
->src_reg
,
2662 if (loop_dump_stream
)
2663 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2664 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2666 /* Set up the mapping from the original biv register to the new
2668 bl
->biv
->src_reg
= tem
;
2675 /* For every giv based on the biv BL, check to determine whether it is
2676 splittable. This is a subroutine to find_splittable_regs ().
2678 Return the number of instructions that set splittable registers. */
2681 find_splittable_givs (loop
, bl
, unroll_type
, increment
, unroll_number
)
2682 const struct loop
*loop
;
2683 struct iv_class
*bl
;
2684 enum unroll_types unroll_type
;
2686 int unroll_number ATTRIBUTE_UNUSED
;
2688 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
2689 struct induction
*v
, *v2
;
2694 /* Scan the list of givs, and set the same_insn field when there are
2695 multiple identical givs in the same insn. */
2696 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2697 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2698 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2702 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2706 /* Only split the giv if it has already been reduced, or if the loop is
2707 being completely unrolled. */
2708 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2711 /* The giv can be split if the insn that sets the giv is executed once
2712 and only once on every iteration of the loop. */
2713 /* An address giv can always be split. v->insn is just a use not a set,
2714 and hence it does not matter whether it is always executed. All that
2715 matters is that all the biv increments are always executed, and we
2716 won't reach here if they aren't. */
2717 if (v
->giv_type
!= DEST_ADDR
2718 && (! v
->always_computable
2719 || back_branch_in_range_p (loop
, v
->insn
)))
2722 /* The giv increment value must be a constant. */
2723 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2725 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2728 /* The loop must be unrolled completely, or else have a known number of
2729 iterations and only one exit, or else the giv must be dead outside
2730 the loop, or else the final value of the giv must be known.
2731 Otherwise, it is not safe to split the giv since it may not have the
2732 proper value on loop exit. */
2734 /* The used outside loop test will fail for DEST_ADDR givs. They are
2735 never used outside the loop anyways, so it is always safe to split a
2739 if (unroll_type
!= UNROLL_COMPLETELY
2740 && (loop
->exit_count
|| unroll_type
== UNROLL_NAIVE
)
2741 && v
->giv_type
!= DEST_ADDR
2742 /* The next part is true if the pseudo is used outside the loop.
2743 We assume that this is true for any pseudo created after loop
2744 starts, because we don't have a reg_n_info entry for them. */
2745 && (REGNO (v
->dest_reg
) >= max_reg_before_loop
2746 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
)) != INSN_UID (v
->insn
)
2747 /* Check for the case where the pseudo is set by a shift/add
2748 sequence, in which case the first insn setting the pseudo
2749 is the first insn of the shift/add sequence. */
2750 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2751 || (REGNO_FIRST_UID (REGNO (v
->dest_reg
))
2752 != INSN_UID (XEXP (tem
, 0)))))
2753 /* Line above always fails if INSN was moved by loop opt. */
2754 || (REGNO_LAST_LUID (REGNO (v
->dest_reg
))
2755 >= INSN_LUID (loop
->end
)))
2756 && ! (final_value
= v
->final_value
))
2760 /* Currently, non-reduced/final-value givs are never split. */
2761 /* Should emit insns after the loop if possible, as the biv final value
2764 /* If the final value is nonzero, and the giv has not been reduced,
2765 then must emit an instruction to set the final value. */
2766 if (final_value
&& !v
->new_reg
)
2768 /* Create a new register to hold the value of the giv, and then set
2769 the giv to its final value before the loop start. The giv is set
2770 to its final value before loop start to ensure that this insn
2771 will always be executed, no matter how we exit. */
2772 tem
= gen_reg_rtx (v
->mode
);
2773 loop_insn_hoist (loop
, gen_move_insn (tem
, v
->dest_reg
));
2774 loop_insn_hoist (loop
, gen_move_insn (v
->dest_reg
, final_value
));
2776 if (loop_dump_stream
)
2777 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2778 REGNO (v
->dest_reg
), REGNO (tem
));
2784 /* This giv is splittable. If completely unrolling the loop, save the
2785 giv's initial value. Otherwise, save the constant zero for it. */
2787 if (unroll_type
== UNROLL_COMPLETELY
)
2789 /* It is not safe to use bl->initial_value here, because it may not
2790 be invariant. It is safe to use the initial value stored in
2791 the splittable_regs array if it is set. In rare cases, it won't
2792 be set, so then we do exactly the same thing as
2793 find_splittable_regs does to get a safe value. */
2794 rtx biv_initial_value
;
2796 if (splittable_regs
[bl
->regno
])
2797 biv_initial_value
= splittable_regs
[bl
->regno
];
2798 else if (GET_CODE (bl
->initial_value
) != REG
2799 || (REGNO (bl
->initial_value
) != bl
->regno
2800 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2801 biv_initial_value
= bl
->initial_value
;
2804 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2806 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
2807 loop_insn_hoist (loop
, gen_move_insn (tem
, bl
->biv
->src_reg
));
2808 biv_initial_value
= tem
;
2810 biv_initial_value
= extend_value_for_giv (v
, biv_initial_value
);
2811 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2812 v
->add_val
, v
->mode
);
2819 /* If a giv was combined with another giv, then we can only split
2820 this giv if the giv it was combined with was reduced. This
2821 is because the value of v->new_reg is meaningless in this
2823 if (v
->same
&& ! v
->same
->new_reg
)
2825 if (loop_dump_stream
)
2826 fprintf (loop_dump_stream
,
2827 "giv combined with unreduced giv not split.\n");
2830 /* If the giv is an address destination, it could be something other
2831 than a simple register, these have to be treated differently. */
2832 else if (v
->giv_type
== DEST_REG
)
2834 /* If value is not a constant, register, or register plus
2835 constant, then compute its value into a register before
2836 loop start. This prevents invalid rtx sharing, and should
2837 generate better code. We can use bl->initial_value here
2838 instead of splittable_regs[bl->regno] because this code
2839 is going before the loop start. */
2840 if (unroll_type
== UNROLL_COMPLETELY
2841 && GET_CODE (value
) != CONST_INT
2842 && GET_CODE (value
) != REG
2843 && (GET_CODE (value
) != PLUS
2844 || GET_CODE (XEXP (value
, 0)) != REG
2845 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2847 rtx tem
= gen_reg_rtx (v
->mode
);
2848 record_base_value (REGNO (tem
), v
->add_val
, 0);
2849 loop_iv_add_mult_hoist (loop
, bl
->initial_value
, v
->mult_val
,
2854 splittable_regs
[reg_or_subregno (v
->new_reg
)] = value
;
2862 /* Currently, unreduced giv's can't be split. This is not too much
2863 of a problem since unreduced giv's are not live across loop
2864 iterations anyways. When unrolling a loop completely though,
2865 it makes sense to reduce&split givs when possible, as this will
2866 result in simpler instructions, and will not require that a reg
2867 be live across loop iterations. */
2869 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
2870 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
2871 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
2877 /* Unreduced givs are only updated once by definition. Reduced givs
2878 are updated as many times as their biv is. Mark it so if this is
2879 a splittable register. Don't need to do anything for address givs
2880 where this may not be a register. */
2882 if (GET_CODE (v
->new_reg
) == REG
)
2886 count
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
))->biv_count
;
2888 splittable_regs_updates
[reg_or_subregno (v
->new_reg
)] = count
;
2893 if (loop_dump_stream
)
2897 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
2899 else if (GET_CODE (v
->dest_reg
) != REG
)
2900 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
2902 regnum
= REGNO (v
->dest_reg
);
2903 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
2904 regnum
, INSN_UID (v
->insn
));
2911 /* Try to prove that the register is dead after the loop exits. Trace every
2912 loop exit looking for an insn that will always be executed, which sets
2913 the register to some value, and appears before the first use of the register
2914 is found. If successful, then return 1, otherwise return 0. */
2916 /* ?? Could be made more intelligent in the handling of jumps, so that
2917 it can search past if statements and other similar structures. */
2920 reg_dead_after_loop (loop
, reg
)
2921 const struct loop
*loop
;
2927 int label_count
= 0;
2929 /* In addition to checking all exits of this loop, we must also check
2930 all exits of inner nested loops that would exit this loop. We don't
2931 have any way to identify those, so we just give up if there are any
2932 such inner loop exits. */
2934 for (label
= loop
->exit_labels
; label
; label
= LABEL_NEXTREF (label
))
2937 if (label_count
!= loop
->exit_count
)
2940 /* HACK: Must also search the loop fall through exit, create a label_ref
2941 here which points to the loop->end, and append the loop_number_exit_labels
2943 label
= gen_rtx_LABEL_REF (VOIDmode
, loop
->end
);
2944 LABEL_NEXTREF (label
) = loop
->exit_labels
;
2946 for (; label
; label
= LABEL_NEXTREF (label
))
2948 /* Succeed if find an insn which sets the biv or if reach end of
2949 function. Fail if find an insn that uses the biv, or if come to
2950 a conditional jump. */
2952 insn
= NEXT_INSN (XEXP (label
, 0));
2955 code
= GET_CODE (insn
);
2956 if (GET_RTX_CLASS (code
) == 'i')
2960 if (reg_referenced_p (reg
, PATTERN (insn
)))
2963 set
= single_set (insn
);
2964 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
2968 if (code
== JUMP_INSN
)
2970 if (GET_CODE (PATTERN (insn
)) == RETURN
)
2972 else if (!any_uncondjump_p (insn
)
2973 /* Prevent infinite loop following infinite loops. */
2974 || jump_count
++ > 20)
2977 insn
= JUMP_LABEL (insn
);
2980 insn
= NEXT_INSN (insn
);
2984 /* Success, the register is dead on all loop exits. */
2988 /* Try to calculate the final value of the biv, the value it will have at
2989 the end of the loop. If we can do it, return that value. */
2992 final_biv_value (loop
, bl
)
2993 const struct loop
*loop
;
2994 struct iv_class
*bl
;
2996 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
2999 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3001 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3004 /* The final value for reversed bivs must be calculated differently than
3005 for ordinary bivs. In this case, there is already an insn after the
3006 loop which sets this biv's final value (if necessary), and there are
3007 no other loop exits, so we can return any value. */
3010 if (loop_dump_stream
)
3011 fprintf (loop_dump_stream
,
3012 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3017 /* Try to calculate the final value as initial value + (number of iterations
3018 * increment). For this to work, increment must be invariant, the only
3019 exit from the loop must be the fall through at the bottom (otherwise
3020 it may not have its final value when the loop exits), and the initial
3021 value of the biv must be invariant. */
3023 if (n_iterations
!= 0
3024 && ! loop
->exit_count
3025 && loop_invariant_p (loop
, bl
->initial_value
))
3027 increment
= biv_total_increment (bl
);
3029 if (increment
&& loop_invariant_p (loop
, increment
))
3031 /* Can calculate the loop exit value, emit insns after loop
3032 end to calculate this value into a temporary register in
3033 case it is needed later. */
3035 tem
= gen_reg_rtx (bl
->biv
->mode
);
3036 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3037 loop_iv_add_mult_sink (loop
, increment
, GEN_INT (n_iterations
),
3038 bl
->initial_value
, tem
);
3040 if (loop_dump_stream
)
3041 fprintf (loop_dump_stream
,
3042 "Final biv value for %d, calculated.\n", bl
->regno
);
3048 /* Check to see if the biv is dead at all loop exits. */
3049 if (reg_dead_after_loop (loop
, bl
->biv
->src_reg
))
3051 if (loop_dump_stream
)
3052 fprintf (loop_dump_stream
,
3053 "Final biv value for %d, biv dead after loop exit.\n",
3062 /* Try to calculate the final value of the giv, the value it will have at
3063 the end of the loop. If we can do it, return that value. */
3066 final_giv_value (loop
, v
)
3067 const struct loop
*loop
;
3068 struct induction
*v
;
3070 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3071 struct iv_class
*bl
;
3075 rtx loop_end
= loop
->end
;
3076 unsigned HOST_WIDE_INT n_iterations
= LOOP_INFO (loop
)->n_iterations
;
3078 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
3080 /* The final value for givs which depend on reversed bivs must be calculated
3081 differently than for ordinary givs. In this case, there is already an
3082 insn after the loop which sets this giv's final value (if necessary),
3083 and there are no other loop exits, so we can return any value. */
3086 if (loop_dump_stream
)
3087 fprintf (loop_dump_stream
,
3088 "Final giv value for %d, depends on reversed biv\n",
3089 REGNO (v
->dest_reg
));
3093 /* Try to calculate the final value as a function of the biv it depends
3094 upon. The only exit from the loop must be the fall through at the bottom
3095 and the insn that sets the giv must be executed on every iteration
3096 (otherwise the giv may not have its final value when the loop exits). */
3098 /* ??? Can calculate the final giv value by subtracting off the
3099 extra biv increments times the giv's mult_val. The loop must have
3100 only one exit for this to work, but the loop iterations does not need
3103 if (n_iterations
!= 0
3104 && ! loop
->exit_count
3105 && v
->always_executed
)
3107 /* ?? It is tempting to use the biv's value here since these insns will
3108 be put after the loop, and hence the biv will have its final value
3109 then. However, this fails if the biv is subsequently eliminated.
3110 Perhaps determine whether biv's are eliminable before trying to
3111 determine whether giv's are replaceable so that we can use the
3112 biv value here if it is not eliminable. */
3114 /* We are emitting code after the end of the loop, so we must make
3115 sure that bl->initial_value is still valid then. It will still
3116 be valid if it is invariant. */
3118 increment
= biv_total_increment (bl
);
3120 if (increment
&& loop_invariant_p (loop
, increment
)
3121 && loop_invariant_p (loop
, bl
->initial_value
))
3123 /* Can calculate the loop exit value of its biv as
3124 (n_iterations * increment) + initial_value */
3126 /* The loop exit value of the giv is then
3127 (final_biv_value - extra increments) * mult_val + add_val.
3128 The extra increments are any increments to the biv which
3129 occur in the loop after the giv's value is calculated.
3130 We must search from the insn that sets the giv to the end
3131 of the loop to calculate this value. */
3133 /* Put the final biv value in tem. */
3134 tem
= gen_reg_rtx (v
->mode
);
3135 record_base_value (REGNO (tem
), bl
->biv
->add_val
, 0);
3136 loop_iv_add_mult_sink (loop
, extend_value_for_giv (v
, increment
),
3137 GEN_INT (n_iterations
),
3138 extend_value_for_giv (v
, bl
->initial_value
),
3141 /* Subtract off extra increments as we find them. */
3142 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3143 insn
= NEXT_INSN (insn
))
3145 struct induction
*biv
;
3147 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3148 if (biv
->insn
== insn
)
3151 tem
= expand_simple_binop (GET_MODE (tem
), MINUS
, tem
,
3152 biv
->add_val
, NULL_RTX
, 0,
3156 loop_insn_sink (loop
, seq
);
3160 /* Now calculate the giv's final value. */
3161 loop_iv_add_mult_sink (loop
, tem
, v
->mult_val
, v
->add_val
, tem
);
3163 if (loop_dump_stream
)
3164 fprintf (loop_dump_stream
,
3165 "Final giv value for %d, calc from biv's value.\n",
3166 REGNO (v
->dest_reg
));
3172 /* Replaceable giv's should never reach here. */
3176 /* Check to see if the biv is dead at all loop exits. */
3177 if (reg_dead_after_loop (loop
, v
->dest_reg
))
3179 if (loop_dump_stream
)
3180 fprintf (loop_dump_stream
,
3181 "Final giv value for %d, giv dead after loop exit.\n",
3182 REGNO (v
->dest_reg
));
3190 /* Look back before LOOP->START for the insn that sets REG and return
3191 the equivalent constant if there is a REG_EQUAL note otherwise just
3192 the SET_SRC of REG. */
3195 loop_find_equiv_value (loop
, reg
)
3196 const struct loop
*loop
;
3199 rtx loop_start
= loop
->start
;
3204 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3206 if (GET_CODE (insn
) == CODE_LABEL
)
3209 else if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3211 /* We found the last insn before the loop that sets the register.
3212 If it sets the entire register, and has a REG_EQUAL note,
3213 then use the value of the REG_EQUAL note. */
3214 if ((set
= single_set (insn
))
3215 && (SET_DEST (set
) == reg
))
3217 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3219 /* Only use the REG_EQUAL note if it is a constant.
3220 Other things, divide in particular, will cause
3221 problems later if we use them. */
3222 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3223 && CONSTANT_P (XEXP (note
, 0)))
3224 ret
= XEXP (note
, 0);
3226 ret
= SET_SRC (set
);
3228 /* We cannot do this if it changes between the
3229 assignment and loop start though. */
3230 if (modified_between_p (ret
, insn
, loop_start
))
3239 /* Return a simplified rtx for the expression OP - REG.
3241 REG must appear in OP, and OP must be a register or the sum of a register
3244 Thus, the return value must be const0_rtx or the second term.
3246 The caller is responsible for verifying that REG appears in OP and OP has
3250 subtract_reg_term (op
, reg
)
3255 if (GET_CODE (op
) == PLUS
)
3257 if (XEXP (op
, 0) == reg
)
3258 return XEXP (op
, 1);
3259 else if (XEXP (op
, 1) == reg
)
3260 return XEXP (op
, 0);
3262 /* OP does not contain REG as a term. */
3266 /* Find and return register term common to both expressions OP0 and
3267 OP1 or NULL_RTX if no such term exists. Each expression must be a
3268 REG or a PLUS of a REG. */
3271 find_common_reg_term (op0
, op1
)
3274 if ((GET_CODE (op0
) == REG
|| GET_CODE (op0
) == PLUS
)
3275 && (GET_CODE (op1
) == REG
|| GET_CODE (op1
) == PLUS
))
3282 if (GET_CODE (op0
) == PLUS
)
3283 op01
= XEXP (op0
, 1), op00
= XEXP (op0
, 0);
3285 op01
= const0_rtx
, op00
= op0
;
3287 if (GET_CODE (op1
) == PLUS
)
3288 op11
= XEXP (op1
, 1), op10
= XEXP (op1
, 0);
3290 op11
= const0_rtx
, op10
= op1
;
3292 /* Find and return common register term if present. */
3293 if (REG_P (op00
) && (op00
== op10
|| op00
== op11
))
3295 else if (REG_P (op01
) && (op01
== op10
|| op01
== op11
))
3299 /* No common register term found. */
3303 /* Determine the loop iterator and calculate the number of loop
3304 iterations. Returns the exact number of loop iterations if it can
3305 be calculated, otherwise returns zero. */
3307 unsigned HOST_WIDE_INT
3308 loop_iterations (loop
)
3311 struct loop_info
*loop_info
= LOOP_INFO (loop
);
3312 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3313 rtx comparison
, comparison_value
;
3314 rtx iteration_var
, initial_value
, increment
, final_value
;
3315 enum rtx_code comparison_code
;
3317 unsigned HOST_WIDE_INT abs_inc
;
3318 unsigned HOST_WIDE_INT abs_diff
;
3321 int unsigned_p
, compare_dir
, final_larger
;
3324 struct iv_class
*bl
;
3326 loop_info
->n_iterations
= 0;
3327 loop_info
->initial_value
= 0;
3328 loop_info
->initial_equiv_value
= 0;
3329 loop_info
->comparison_value
= 0;
3330 loop_info
->final_value
= 0;
3331 loop_info
->final_equiv_value
= 0;
3332 loop_info
->increment
= 0;
3333 loop_info
->iteration_var
= 0;
3334 loop_info
->unroll_number
= 1;
3337 /* We used to use prev_nonnote_insn here, but that fails because it might
3338 accidentally get the branch for a contained loop if the branch for this
3339 loop was deleted. We can only trust branches immediately before the
3341 last_loop_insn
= PREV_INSN (loop
->end
);
3343 /* ??? We should probably try harder to find the jump insn
3344 at the end of the loop. The following code assumes that
3345 the last loop insn is a jump to the top of the loop. */
3346 if (GET_CODE (last_loop_insn
) != JUMP_INSN
)
3348 if (loop_dump_stream
)
3349 fprintf (loop_dump_stream
,
3350 "Loop iterations: No final conditional branch found.\n");
3354 /* If there is a more than a single jump to the top of the loop
3355 we cannot (easily) determine the iteration count. */
3356 if (LABEL_NUSES (JUMP_LABEL (last_loop_insn
)) > 1)
3358 if (loop_dump_stream
)
3359 fprintf (loop_dump_stream
,
3360 "Loop iterations: Loop has multiple back edges.\n");
3364 /* If there are multiple conditionalized loop exit tests, they may jump
3365 back to differing CODE_LABELs. */
3366 if (loop
->top
&& loop
->cont
)
3368 rtx temp
= PREV_INSN (last_loop_insn
);
3372 if (GET_CODE (temp
) == JUMP_INSN
)
3374 /* There are some kinds of jumps we can't deal with easily. */
3375 if (JUMP_LABEL (temp
) == 0)
3377 if (loop_dump_stream
)
3380 "Loop iterations: Jump insn has null JUMP_LABEL.\n");
3384 if (/* Previous unrolling may have generated new insns not
3385 covered by the uid_luid array. */
3386 INSN_UID (JUMP_LABEL (temp
)) < max_uid_for_loop
3387 /* Check if we jump back into the loop body. */
3388 && INSN_LUID (JUMP_LABEL (temp
)) > INSN_LUID (loop
->top
)
3389 && INSN_LUID (JUMP_LABEL (temp
)) < INSN_LUID (loop
->cont
))
3391 if (loop_dump_stream
)
3394 "Loop iterations: Loop has multiple back edges.\n");
3399 while ((temp
= PREV_INSN (temp
)) != loop
->cont
);
3402 /* Find the iteration variable. If the last insn is a conditional
3403 branch, and the insn before tests a register value, make that the
3404 iteration variable. */
3406 comparison
= get_condition_for_loop (loop
, last_loop_insn
);
3407 if (comparison
== 0)
3409 if (loop_dump_stream
)
3410 fprintf (loop_dump_stream
,
3411 "Loop iterations: No final comparison found.\n");
3415 /* ??? Get_condition may switch position of induction variable and
3416 invariant register when it canonicalizes the comparison. */
3418 comparison_code
= GET_CODE (comparison
);
3419 iteration_var
= XEXP (comparison
, 0);
3420 comparison_value
= XEXP (comparison
, 1);
3422 if (GET_CODE (iteration_var
) != REG
)
3424 if (loop_dump_stream
)
3425 fprintf (loop_dump_stream
,
3426 "Loop iterations: Comparison not against register.\n");
3430 /* The only new registers that are created before loop iterations
3431 are givs made from biv increments or registers created by
3432 load_mems. In the latter case, it is possible that try_copy_prop
3433 will propagate a new pseudo into the old iteration register but
3434 this will be marked by having the REG_USERVAR_P bit set. */
3436 if ((unsigned) REGNO (iteration_var
) >= ivs
->n_regs
3437 && ! REG_USERVAR_P (iteration_var
))
3440 /* Determine the initial value of the iteration variable, and the amount
3441 that it is incremented each loop. Use the tables constructed by
3442 the strength reduction pass to calculate these values. */
3444 /* Clear the result values, in case no answer can be found. */
3448 /* The iteration variable can be either a giv or a biv. Check to see
3449 which it is, and compute the variable's initial value, and increment
3450 value if possible. */
3452 /* If this is a new register, can't handle it since we don't have any
3453 reg_iv_type entry for it. */
3454 if ((unsigned) REGNO (iteration_var
) >= ivs
->n_regs
)
3456 if (loop_dump_stream
)
3457 fprintf (loop_dump_stream
,
3458 "Loop iterations: No reg_iv_type entry for iteration var.\n");
3462 /* Reject iteration variables larger than the host wide int size, since they
3463 could result in a number of iterations greater than the range of our
3464 `unsigned HOST_WIDE_INT' variable loop_info->n_iterations. */
3465 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
3466 > HOST_BITS_PER_WIDE_INT
))
3468 if (loop_dump_stream
)
3469 fprintf (loop_dump_stream
,
3470 "Loop iterations: Iteration var rejected because mode too large.\n");
3473 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
3475 if (loop_dump_stream
)
3476 fprintf (loop_dump_stream
,
3477 "Loop iterations: Iteration var not an integer.\n");
3480 else if (REG_IV_TYPE (ivs
, REGNO (iteration_var
)) == BASIC_INDUCT
)
3482 if (REGNO (iteration_var
) >= ivs
->n_regs
)
3485 /* Grab initial value, only useful if it is a constant. */
3486 bl
= REG_IV_CLASS (ivs
, REGNO (iteration_var
));
3487 initial_value
= bl
->initial_value
;
3488 if (!bl
->biv
->always_executed
|| bl
->biv
->maybe_multiple
)
3490 if (loop_dump_stream
)
3491 fprintf (loop_dump_stream
,
3492 "Loop iterations: Basic induction var not set once in each iteration.\n");
3496 increment
= biv_total_increment (bl
);
3498 else if (REG_IV_TYPE (ivs
, REGNO (iteration_var
)) == GENERAL_INDUCT
)
3500 HOST_WIDE_INT offset
= 0;
3501 struct induction
*v
= REG_IV_INFO (ivs
, REGNO (iteration_var
));
3502 rtx biv_initial_value
;
3504 if (REGNO (v
->src_reg
) >= ivs
->n_regs
)
3507 if (!v
->always_executed
|| v
->maybe_multiple
)
3509 if (loop_dump_stream
)
3510 fprintf (loop_dump_stream
,
3511 "Loop iterations: General induction var not set once in each iteration.\n");
3515 bl
= REG_IV_CLASS (ivs
, REGNO (v
->src_reg
));
3517 /* Increment value is mult_val times the increment value of the biv. */
3519 increment
= biv_total_increment (bl
);
3522 struct induction
*biv_inc
;
3524 increment
= fold_rtx_mult_add (v
->mult_val
,
3525 extend_value_for_giv (v
, increment
),
3526 const0_rtx
, v
->mode
);
3527 /* The caller assumes that one full increment has occurred at the
3528 first loop test. But that's not true when the biv is incremented
3529 after the giv is set (which is the usual case), e.g.:
3530 i = 6; do {;} while (i++ < 9) .
3531 Therefore, we bias the initial value by subtracting the amount of
3532 the increment that occurs between the giv set and the giv test. */
3533 for (biv_inc
= bl
->biv
; biv_inc
; biv_inc
= biv_inc
->next_iv
)
3535 if (loop_insn_first_p (v
->insn
, biv_inc
->insn
))
3537 if (REG_P (biv_inc
->add_val
))
3539 if (loop_dump_stream
)
3540 fprintf (loop_dump_stream
,
3541 "Loop iterations: Basic induction var add_val is REG %d.\n",
3542 REGNO (biv_inc
->add_val
));
3546 offset
-= INTVAL (biv_inc
->add_val
);
3550 if (loop_dump_stream
)
3551 fprintf (loop_dump_stream
,
3552 "Loop iterations: Giv iterator, initial value bias %ld.\n",
3555 /* Initial value is mult_val times the biv's initial value plus
3556 add_val. Only useful if it is a constant. */
3557 biv_initial_value
= extend_value_for_giv (v
, bl
->initial_value
);
3559 = fold_rtx_mult_add (v
->mult_val
,
3560 plus_constant (biv_initial_value
, offset
),
3561 v
->add_val
, v
->mode
);
3565 if (loop_dump_stream
)
3566 fprintf (loop_dump_stream
,
3567 "Loop iterations: Not basic or general induction var.\n");
3571 if (initial_value
== 0)
3576 switch (comparison_code
)
3591 /* Cannot determine loop iterations with this case. */
3610 /* If the comparison value is an invariant register, then try to find
3611 its value from the insns before the start of the loop. */
3613 final_value
= comparison_value
;
3614 if (GET_CODE (comparison_value
) == REG
3615 && loop_invariant_p (loop
, comparison_value
))
3617 final_value
= loop_find_equiv_value (loop
, comparison_value
);
3619 /* If we don't get an invariant final value, we are better
3620 off with the original register. */
3621 if (! loop_invariant_p (loop
, final_value
))
3622 final_value
= comparison_value
;
3625 /* Calculate the approximate final value of the induction variable
3626 (on the last successful iteration). The exact final value
3627 depends on the branch operator, and increment sign. It will be
3628 wrong if the iteration variable is not incremented by one each
3629 time through the loop and (comparison_value + off_by_one -
3630 initial_value) % increment != 0.
3631 ??? Note that the final_value may overflow and thus final_larger
3632 will be bogus. A potentially infinite loop will be classified
3633 as immediate, e.g. for (i = 0x7ffffff0; i <= 0x7fffffff; i++) */
3635 final_value
= plus_constant (final_value
, off_by_one
);
3637 /* Save the calculated values describing this loop's bounds, in case
3638 precondition_loop_p will need them later. These values can not be
3639 recalculated inside precondition_loop_p because strength reduction
3640 optimizations may obscure the loop's structure.
3642 These values are only required by precondition_loop_p and insert_bct
3643 whenever the number of iterations cannot be computed at compile time.
3644 Only the difference between final_value and initial_value is
3645 important. Note that final_value is only approximate. */
3646 loop_info
->initial_value
= initial_value
;
3647 loop_info
->comparison_value
= comparison_value
;
3648 loop_info
->final_value
= plus_constant (comparison_value
, off_by_one
);
3649 loop_info
->increment
= increment
;
3650 loop_info
->iteration_var
= iteration_var
;
3651 loop_info
->comparison_code
= comparison_code
;
3654 /* Try to determine the iteration count for loops such
3655 as (for i = init; i < init + const; i++). When running the
3656 loop optimization twice, the first pass often converts simple
3657 loops into this form. */
3659 if (REG_P (initial_value
))
3665 reg1
= initial_value
;
3666 if (GET_CODE (final_value
) == PLUS
)
3667 reg2
= XEXP (final_value
, 0), const2
= XEXP (final_value
, 1);
3669 reg2
= final_value
, const2
= const0_rtx
;
3671 /* Check for initial_value = reg1, final_value = reg2 + const2,
3672 where reg1 != reg2. */
3673 if (REG_P (reg2
) && reg2
!= reg1
)
3677 /* Find what reg1 is equivalent to. Hopefully it will
3678 either be reg2 or reg2 plus a constant. */
3679 temp
= loop_find_equiv_value (loop
, reg1
);
3681 if (find_common_reg_term (temp
, reg2
))
3682 initial_value
= temp
;
3685 /* Find what reg2 is equivalent to. Hopefully it will
3686 either be reg1 or reg1 plus a constant. Let's ignore
3687 the latter case for now since it is not so common. */
3688 temp
= loop_find_equiv_value (loop
, reg2
);
3690 if (temp
== loop_info
->iteration_var
)
3691 temp
= initial_value
;
3693 final_value
= (const2
== const0_rtx
)
3694 ? reg1
: gen_rtx_PLUS (GET_MODE (reg1
), reg1
, const2
);
3697 else if (loop
->vtop
&& GET_CODE (reg2
) == CONST_INT
)
3701 /* When running the loop optimizer twice, check_dbra_loop
3702 further obfuscates reversible loops of the form:
3703 for (i = init; i < init + const; i++). We often end up with
3704 final_value = 0, initial_value = temp, temp = temp2 - init,
3705 where temp2 = init + const. If the loop has a vtop we
3706 can replace initial_value with const. */
3708 temp
= loop_find_equiv_value (loop
, reg1
);
3710 if (GET_CODE (temp
) == MINUS
&& REG_P (XEXP (temp
, 0)))
3712 rtx temp2
= loop_find_equiv_value (loop
, XEXP (temp
, 0));
3714 if (GET_CODE (temp2
) == PLUS
3715 && XEXP (temp2
, 0) == XEXP (temp
, 1))
3716 initial_value
= XEXP (temp2
, 1);
3721 /* If have initial_value = reg + const1 and final_value = reg +
3722 const2, then replace initial_value with const1 and final_value
3723 with const2. This should be safe since we are protected by the
3724 initial comparison before entering the loop if we have a vtop.
3725 For example, a + b < a + c is not equivalent to b < c for all a
3726 when using modulo arithmetic.
3728 ??? Without a vtop we could still perform the optimization if we check
3729 the initial and final values carefully. */
3731 && (reg_term
= find_common_reg_term (initial_value
, final_value
)))
3733 initial_value
= subtract_reg_term (initial_value
, reg_term
);
3734 final_value
= subtract_reg_term (final_value
, reg_term
);
3737 loop_info
->initial_equiv_value
= initial_value
;
3738 loop_info
->final_equiv_value
= final_value
;
3740 /* For EQ comparison loops, we don't have a valid final value.
3741 Check this now so that we won't leave an invalid value if we
3742 return early for any other reason. */
3743 if (comparison_code
== EQ
)
3744 loop_info
->final_equiv_value
= loop_info
->final_value
= 0;
3748 if (loop_dump_stream
)
3749 fprintf (loop_dump_stream
,
3750 "Loop iterations: Increment value can't be calculated.\n");
3754 if (GET_CODE (increment
) != CONST_INT
)
3756 /* If we have a REG, check to see if REG holds a constant value. */
3757 /* ??? Other RTL, such as (neg (reg)) is possible here, but it isn't
3758 clear if it is worthwhile to try to handle such RTL. */
3759 if (GET_CODE (increment
) == REG
|| GET_CODE (increment
) == SUBREG
)
3760 increment
= loop_find_equiv_value (loop
, increment
);
3762 if (GET_CODE (increment
) != CONST_INT
)
3764 if (loop_dump_stream
)
3766 fprintf (loop_dump_stream
,
3767 "Loop iterations: Increment value not constant ");
3768 print_simple_rtl (loop_dump_stream
, increment
);
3769 fprintf (loop_dump_stream
, ".\n");
3773 loop_info
->increment
= increment
;
3776 if (GET_CODE (initial_value
) != CONST_INT
)
3778 if (loop_dump_stream
)
3780 fprintf (loop_dump_stream
,
3781 "Loop iterations: Initial value not constant ");
3782 print_simple_rtl (loop_dump_stream
, initial_value
);
3783 fprintf (loop_dump_stream
, ".\n");
3787 else if (GET_CODE (final_value
) != CONST_INT
)
3789 if (loop_dump_stream
)
3791 fprintf (loop_dump_stream
,
3792 "Loop iterations: Final value not constant ");
3793 print_simple_rtl (loop_dump_stream
, final_value
);
3794 fprintf (loop_dump_stream
, ".\n");
3798 else if (comparison_code
== EQ
)
3802 if (loop_dump_stream
)
3803 fprintf (loop_dump_stream
, "Loop iterations: EQ comparison loop.\n");
3805 inc_once
= gen_int_mode (INTVAL (initial_value
) + INTVAL (increment
),
3806 GET_MODE (iteration_var
));
3808 if (inc_once
== final_value
)
3810 /* The iterator value once through the loop is equal to the
3811 comparison value. Either we have an infinite loop, or
3812 we'll loop twice. */
3813 if (increment
== const0_rtx
)
3815 loop_info
->n_iterations
= 2;
3818 loop_info
->n_iterations
= 1;
3820 if (GET_CODE (loop_info
->initial_value
) == CONST_INT
)
3821 loop_info
->final_value
3822 = gen_int_mode ((INTVAL (loop_info
->initial_value
)
3823 + loop_info
->n_iterations
* INTVAL (increment
)),
3824 GET_MODE (iteration_var
));
3826 loop_info
->final_value
3827 = plus_constant (loop_info
->initial_value
,
3828 loop_info
->n_iterations
* INTVAL (increment
));
3829 loop_info
->final_equiv_value
3830 = gen_int_mode ((INTVAL (initial_value
)
3831 + loop_info
->n_iterations
* INTVAL (increment
)),
3832 GET_MODE (iteration_var
));
3833 return loop_info
->n_iterations
;
3836 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3839 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3840 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3841 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3842 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3844 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3845 - (INTVAL (final_value
) < INTVAL (initial_value
));
3847 if (INTVAL (increment
) > 0)
3849 else if (INTVAL (increment
) == 0)
3854 /* There are 27 different cases: compare_dir = -1, 0, 1;
3855 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3856 There are 4 normal cases, 4 reverse cases (where the iteration variable
3857 will overflow before the loop exits), 4 infinite loop cases, and 15
3858 immediate exit (0 or 1 iteration depending on loop type) cases.
3859 Only try to optimize the normal cases. */
3861 /* (compare_dir/final_larger/increment_dir)
3862 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3863 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3864 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3865 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3867 /* ?? If the meaning of reverse loops (where the iteration variable
3868 will overflow before the loop exits) is undefined, then could
3869 eliminate all of these special checks, and just always assume
3870 the loops are normal/immediate/infinite. Note that this means
3871 the sign of increment_dir does not have to be known. Also,
3872 since it does not really hurt if immediate exit loops or infinite loops
3873 are optimized, then that case could be ignored also, and hence all
3874 loops can be optimized.
3876 According to ANSI Spec, the reverse loop case result is undefined,
3877 because the action on overflow is undefined.
3879 See also the special test for NE loops below. */
3881 if (final_larger
== increment_dir
&& final_larger
!= 0
3882 && (final_larger
== compare_dir
|| compare_dir
== 0))
3887 if (loop_dump_stream
)
3888 fprintf (loop_dump_stream
, "Loop iterations: Not normal loop.\n");
3892 /* Calculate the number of iterations, final_value is only an approximation,
3893 so correct for that. Note that abs_diff and n_iterations are
3894 unsigned, because they can be as large as 2^n - 1. */
3896 inc
= INTVAL (increment
);
3899 abs_diff
= INTVAL (final_value
) - INTVAL (initial_value
);
3904 abs_diff
= INTVAL (initial_value
) - INTVAL (final_value
);
3910 /* Given that iteration_var is going to iterate over its own mode,
3911 not HOST_WIDE_INT, disregard higher bits that might have come
3912 into the picture due to sign extension of initial and final
3914 abs_diff
&= ((unsigned HOST_WIDE_INT
) 1
3915 << (GET_MODE_BITSIZE (GET_MODE (iteration_var
)) - 1)
3918 /* For NE tests, make sure that the iteration variable won't miss
3919 the final value. If abs_diff mod abs_incr is not zero, then the
3920 iteration variable will overflow before the loop exits, and we
3921 can not calculate the number of iterations. */
3922 if (compare_dir
== 0 && (abs_diff
% abs_inc
) != 0)
3925 /* Note that the number of iterations could be calculated using
3926 (abs_diff + abs_inc - 1) / abs_inc, provided care was taken to
3927 handle potential overflow of the summation. */
3928 loop_info
->n_iterations
= abs_diff
/ abs_inc
+ ((abs_diff
% abs_inc
) != 0);
3929 return loop_info
->n_iterations
;
3932 /* Replace uses of split bivs with their split pseudo register. This is
3933 for original instructions which remain after loop unrolling without
3937 remap_split_bivs (loop
, x
)
3941 struct loop_ivs
*ivs
= LOOP_IVS (loop
);
3949 code
= GET_CODE (x
);
3964 /* If non-reduced/final-value givs were split, then this would also
3965 have to remap those givs also. */
3967 if (REGNO (x
) < ivs
->n_regs
3968 && REG_IV_TYPE (ivs
, REGNO (x
)) == BASIC_INDUCT
)
3969 return REG_IV_CLASS (ivs
, REGNO (x
))->biv
->src_reg
;
3976 fmt
= GET_RTX_FORMAT (code
);
3977 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3980 XEXP (x
, i
) = remap_split_bivs (loop
, XEXP (x
, i
));
3981 else if (fmt
[i
] == 'E')
3984 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3985 XVECEXP (x
, i
, j
) = remap_split_bivs (loop
, XVECEXP (x
, i
, j
));
3991 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3992 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3993 return 0. COPY_START is where we can start looking for the insns
3994 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3997 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3998 must dominate LAST_UID.
4000 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4001 may not dominate LAST_UID.
4003 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
4004 must dominate LAST_UID. */
4007 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
4014 int passed_jump
= 0;
4015 rtx p
= NEXT_INSN (copy_start
);
4017 while (INSN_UID (p
) != first_uid
)
4019 if (GET_CODE (p
) == JUMP_INSN
)
4021 /* Could not find FIRST_UID. */
4027 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
4028 if (! INSN_P (p
) || ! dead_or_set_regno_p (p
, regno
))
4031 /* FIRST_UID is always executed. */
4032 if (passed_jump
== 0)
4035 while (INSN_UID (p
) != last_uid
)
4037 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
4038 can not be sure that FIRST_UID dominates LAST_UID. */
4039 if (GET_CODE (p
) == CODE_LABEL
)
4041 /* Could not find LAST_UID, but we reached the end of the loop, so
4043 else if (p
== copy_end
)
4048 /* FIRST_UID is always executed if LAST_UID is executed. */
4052 /* This routine is called when the number of iterations for the unrolled
4053 loop is one. The goal is to identify a loop that begins with an
4054 unconditional branch to the loop continuation note (or a label just after).
4055 In this case, the unconditional branch that starts the loop needs to be
4056 deleted so that we execute the single iteration. */
4059 ujump_to_loop_cont (loop_start
, loop_cont
)
4063 rtx x
, label
, label_ref
;
4065 /* See if loop start, or the next insn is an unconditional jump. */
4066 loop_start
= next_nonnote_insn (loop_start
);
4068 x
= pc_set (loop_start
);
4072 label_ref
= SET_SRC (x
);
4076 /* Examine insn after loop continuation note. Return if not a label. */
4077 label
= next_nonnote_insn (loop_cont
);
4078 if (label
== 0 || GET_CODE (label
) != CODE_LABEL
)
4081 /* Return the loop start if the branch label matches the code label. */
4082 if (CODE_LABEL_NUMBER (label
) == CODE_LABEL_NUMBER (XEXP (label_ref
, 0)))