1 /* Try to unroll loops, and split induction variables.
2 Copyright (C) 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
3 Contributed by James E. Wilson, Cygnus Support/UC Berkeley.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
22 /* Try to unroll a loop, and split induction variables.
24 Loops for which the number of iterations can be calculated exactly are
25 handled specially. If the number of iterations times the insn_count is
26 less than MAX_UNROLLED_INSNS, then the loop is unrolled completely.
27 Otherwise, we try to unroll the loop a number of times modulo the number
28 of iterations, so that only one exit test will be needed. It is unrolled
29 a number of times approximately equal to MAX_UNROLLED_INSNS divided by
32 Otherwise, if the number of iterations can be calculated exactly at
33 run time, and the loop is always entered at the top, then we try to
34 precondition the loop. That is, at run time, calculate how many times
35 the loop will execute, and then execute the loop body a few times so
36 that the remaining iterations will be some multiple of 4 (or 2 if the
37 loop is large). Then fall through to a loop unrolled 4 (or 2) times,
38 with only one exit test needed at the end of the loop.
40 Otherwise, if the number of iterations can not be calculated exactly,
41 not even at run time, then we still unroll the loop a number of times
42 approximately equal to MAX_UNROLLED_INSNS divided by the insn count,
43 but there must be an exit test after each copy of the loop body.
45 For each induction variable, which is dead outside the loop (replaceable)
46 or for which we can easily calculate the final value, if we can easily
47 calculate its value at each place where it is set as a function of the
48 current loop unroll count and the variable's value at loop entry, then
49 the induction variable is split into `N' different variables, one for
50 each copy of the loop body. One variable is live across the backward
51 branch, and the others are all calculated as a function of this variable.
52 This helps eliminate data dependencies, and leads to further opportunities
55 /* Possible improvements follow: */
57 /* ??? Add an extra pass somewhere to determine whether unrolling will
58 give any benefit. E.g. after generating all unrolled insns, compute the
59 cost of all insns and compare against cost of insns in rolled loop.
61 - On traditional architectures, unrolling a non-constant bound loop
62 is a win if there is a giv whose only use is in memory addresses, the
63 memory addresses can be split, and hence giv increments can be
65 - It is also a win if the loop is executed many times, and preconditioning
66 can be performed for the loop.
67 Add code to check for these and similar cases. */
69 /* ??? Improve control of which loops get unrolled. Could use profiling
70 info to only unroll the most commonly executed loops. Perhaps have
71 a user specifyable option to control the amount of code expansion,
72 or the percent of loops to consider for unrolling. Etc. */
74 /* ??? Look at the register copies inside the loop to see if they form a
75 simple permutation. If so, iterate the permutation until it gets back to
76 the start state. This is how many times we should unroll the loop, for
77 best results, because then all register copies can be eliminated.
78 For example, the lisp nreverse function should be unrolled 3 times
87 ??? The number of times to unroll the loop may also be based on data
88 references in the loop. For example, if we have a loop that references
89 x[i-1], x[i], and x[i+1], we should unroll it a multiple of 3 times. */
91 /* ??? Add some simple linear equation solving capability so that we can
92 determine the number of loop iterations for more complex loops.
93 For example, consider this loop from gdb
94 #define SWAP_TARGET_AND_HOST(buffer,len)
97 char *p = (char *) buffer;
98 char *q = ((char *) buffer) + len - 1;
99 int iterations = (len + 1) >> 1;
101 for (p; p < q; p++, q--;)
109 start value = p = &buffer + current_iteration
110 end value = q = &buffer + len - 1 - current_iteration
111 Given the loop exit test of "p < q", then there must be "q - p" iterations,
112 set equal to zero and solve for number of iterations:
113 q - p = len - 1 - 2*current_iteration = 0
114 current_iteration = (len - 1) / 2
115 Hence, there are (len - 1) / 2 (rounded up to the nearest integer)
116 iterations of this loop. */
118 /* ??? Currently, no labels are marked as loop invariant when doing loop
119 unrolling. This is because an insn inside the loop, that loads the address
120 of a label inside the loop into a register, could be moved outside the loop
121 by the invariant code motion pass if labels were invariant. If the loop
122 is subsequently unrolled, the code will be wrong because each unrolled
123 body of the loop will use the same address, whereas each actually needs a
124 different address. A case where this happens is when a loop containing
125 a switch statement is unrolled.
127 It would be better to let labels be considered invariant. When we
128 unroll loops here, check to see if any insns using a label local to the
129 loop were moved before the loop. If so, then correct the problem, by
130 moving the insn back into the loop, or perhaps replicate the insn before
131 the loop, one copy for each time the loop is unrolled. */
133 /* The prime factors looked for when trying to unroll a loop by some
134 number which is modulo the total number of iterations. Just checking
135 for these 4 prime factors will find at least one factor for 75% of
136 all numbers theoretically. Practically speaking, this will succeed
137 almost all of the time since loops are generally a multiple of 2
140 #define NUM_FACTORS 4
142 struct _factor
{ int factor
, count
; } factors
[NUM_FACTORS
]
143 = { {2, 0}, {3, 0}, {5, 0}, {7, 0}};
145 /* Describes the different types of loop unrolling performed. */
147 enum unroll_types
{ UNROLL_COMPLETELY
, UNROLL_MODULO
, UNROLL_NAIVE
};
151 #include "insn-config.h"
152 #include "integrate.h"
159 /* This controls which loops are unrolled, and by how much we unroll
162 #ifndef MAX_UNROLLED_INSNS
163 #define MAX_UNROLLED_INSNS 100
166 /* Indexed by register number, if non-zero, then it contains a pointer
167 to a struct induction for a DEST_REG giv which has been combined with
168 one of more address givs. This is needed because whenever such a DEST_REG
169 giv is modified, we must modify the value of all split address givs
170 that were combined with this DEST_REG giv. */
172 static struct induction
**addr_combined_regs
;
174 /* Indexed by register number, if this is a splittable induction variable,
175 then this will hold the current value of the register, which depends on the
178 static rtx
*splittable_regs
;
180 /* Indexed by register number, if this is a splittable induction variable,
181 then this will hold the number of instructions in the loop that modify
182 the induction variable. Used to ensure that only the last insn modifying
183 a split iv will update the original iv of the dest. */
185 static int *splittable_regs_updates
;
187 /* Values describing the current loop's iteration variable. These are set up
188 by loop_iterations, and used by precondition_loop_p. */
190 static rtx loop_iteration_var
;
191 static rtx loop_initial_value
;
192 static rtx loop_increment
;
193 static rtx loop_final_value
;
194 static enum rtx_code loop_comparison_code
;
196 /* Forward declarations. */
198 static void init_reg_map
PROTO((struct inline_remap
*, int));
199 static int precondition_loop_p
PROTO((rtx
*, rtx
*, rtx
*, rtx
, rtx
));
200 static rtx calculate_giv_inc
PROTO((rtx
, rtx
, int));
201 static rtx initial_reg_note_copy
PROTO((rtx
, struct inline_remap
*));
202 static void final_reg_note_copy
PROTO((rtx
, struct inline_remap
*));
203 static void copy_loop_body
PROTO((rtx
, rtx
, struct inline_remap
*, rtx
, int,
204 enum unroll_types
, rtx
, rtx
, rtx
, rtx
));
205 static void iteration_info
PROTO((rtx
, rtx
*, rtx
*, rtx
, rtx
));
206 static rtx approx_final_value
PROTO((enum rtx_code
, rtx
, int *, int *));
207 static int find_splittable_regs
PROTO((enum unroll_types
, rtx
, rtx
, rtx
, int));
208 static int find_splittable_givs
PROTO((struct iv_class
*,enum unroll_types
,
209 rtx
, rtx
, rtx
, int));
210 static int reg_dead_after_loop
PROTO((rtx
, rtx
, rtx
));
211 static rtx fold_rtx_mult_add
PROTO((rtx
, rtx
, rtx
, enum machine_mode
));
212 static rtx remap_split_bivs
PROTO((rtx
));
214 /* Try to unroll one loop and split induction variables in the loop.
216 The loop is described by the arguments LOOP_END, INSN_COUNT, and
217 LOOP_START. END_INSERT_BEFORE indicates where insns should be added
218 which need to be executed when the loop falls through. STRENGTH_REDUCTION_P
219 indicates whether information generated in the strength reduction pass
222 This function is intended to be called from within `strength_reduce'
226 unroll_loop (loop_end
, insn_count
, loop_start
, end_insert_before
,
231 rtx end_insert_before
;
232 int strength_reduce_p
;
235 int unroll_number
= 1;
236 rtx copy_start
, copy_end
;
237 rtx insn
, copy
, sequence
, pattern
, tem
;
238 int max_labelno
, max_insnno
;
240 struct inline_remap
*map
;
248 int splitting_not_safe
= 0;
249 enum unroll_types unroll_type
;
250 int loop_preconditioned
= 0;
252 /* This points to the last real insn in the loop, which should be either
253 a JUMP_INSN (for conditional jumps) or a BARRIER (for unconditional
257 /* Don't bother unrolling huge loops. Since the minimum factor is
258 two, loops greater than one half of MAX_UNROLLED_INSNS will never
260 if (insn_count
> MAX_UNROLLED_INSNS
/ 2)
262 if (loop_dump_stream
)
263 fprintf (loop_dump_stream
, "Unrolling failure: Loop too big.\n");
267 /* When emitting debugger info, we can't unroll loops with unequal numbers
268 of block_beg and block_end notes, because that would unbalance the block
269 structure of the function. This can happen as a result of the
270 "if (foo) bar; else break;" optimization in jump.c. */
271 /* ??? Gcc has a general policy that -g is never supposed to change the code
272 that the compiler emits, so we must disable this optimization always,
273 even if debug info is not being output. This is rare, so this should
274 not be a significant performance problem. */
276 if (1 /* write_symbols != NO_DEBUG */)
278 int block_begins
= 0;
281 for (insn
= loop_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
283 if (GET_CODE (insn
) == NOTE
)
285 if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_BEG
)
287 else if (NOTE_LINE_NUMBER (insn
) == NOTE_INSN_BLOCK_END
)
292 if (block_begins
!= block_ends
)
294 if (loop_dump_stream
)
295 fprintf (loop_dump_stream
,
296 "Unrolling failure: Unbalanced block notes.\n");
301 /* Determine type of unroll to perform. Depends on the number of iterations
302 and the size of the loop. */
304 /* If there is no strength reduce info, then set loop_n_iterations to zero.
305 This can happen if strength_reduce can't find any bivs in the loop.
306 A value of zero indicates that the number of iterations could not be
309 if (! strength_reduce_p
)
310 loop_n_iterations
= 0;
312 if (loop_dump_stream
&& loop_n_iterations
> 0)
313 fprintf (loop_dump_stream
,
314 "Loop unrolling: %d iterations.\n", loop_n_iterations
);
316 /* Find and save a pointer to the last nonnote insn in the loop. */
318 last_loop_insn
= prev_nonnote_insn (loop_end
);
320 /* Calculate how many times to unroll the loop. Indicate whether or
321 not the loop is being completely unrolled. */
323 if (loop_n_iterations
== 1)
325 /* If number of iterations is exactly 1, then eliminate the compare and
326 branch at the end of the loop since they will never be taken.
327 Then return, since no other action is needed here. */
329 /* If the last instruction is not a BARRIER or a JUMP_INSN, then
330 don't do anything. */
332 if (GET_CODE (last_loop_insn
) == BARRIER
)
334 /* Delete the jump insn. This will delete the barrier also. */
335 delete_insn (PREV_INSN (last_loop_insn
));
337 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
340 /* The immediately preceding insn is a compare which must be
342 delete_insn (last_loop_insn
);
343 delete_insn (PREV_INSN (last_loop_insn
));
345 /* The immediately preceding insn may not be the compare, so don't
347 delete_insn (last_loop_insn
);
352 else if (loop_n_iterations
> 0
353 && loop_n_iterations
* insn_count
< MAX_UNROLLED_INSNS
)
355 unroll_number
= loop_n_iterations
;
356 unroll_type
= UNROLL_COMPLETELY
;
358 else if (loop_n_iterations
> 0)
360 /* Try to factor the number of iterations. Don't bother with the
361 general case, only using 2, 3, 5, and 7 will get 75% of all
362 numbers theoretically, and almost all in practice. */
364 for (i
= 0; i
< NUM_FACTORS
; i
++)
365 factors
[i
].count
= 0;
367 temp
= loop_n_iterations
;
368 for (i
= NUM_FACTORS
- 1; i
>= 0; i
--)
369 while (temp
% factors
[i
].factor
== 0)
372 temp
= temp
/ factors
[i
].factor
;
375 /* Start with the larger factors first so that we generally
376 get lots of unrolling. */
380 for (i
= 3; i
>= 0; i
--)
381 while (factors
[i
].count
--)
383 if (temp
* factors
[i
].factor
< MAX_UNROLLED_INSNS
)
385 unroll_number
*= factors
[i
].factor
;
386 temp
*= factors
[i
].factor
;
392 /* If we couldn't find any factors, then unroll as in the normal
394 if (unroll_number
== 1)
396 if (loop_dump_stream
)
397 fprintf (loop_dump_stream
,
398 "Loop unrolling: No factors found.\n");
401 unroll_type
= UNROLL_MODULO
;
405 /* Default case, calculate number of times to unroll loop based on its
407 if (unroll_number
== 1)
409 if (8 * insn_count
< MAX_UNROLLED_INSNS
)
411 else if (4 * insn_count
< MAX_UNROLLED_INSNS
)
416 unroll_type
= UNROLL_NAIVE
;
419 /* Now we know how many times to unroll the loop. */
421 if (loop_dump_stream
)
422 fprintf (loop_dump_stream
,
423 "Unrolling loop %d times.\n", unroll_number
);
426 if (unroll_type
== UNROLL_COMPLETELY
|| unroll_type
== UNROLL_MODULO
)
428 /* Loops of these types should never start with a jump down to
429 the exit condition test. For now, check for this case just to
430 be sure. UNROLL_NAIVE loops can be of this form, this case is
433 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
434 insn
= NEXT_INSN (insn
);
435 if (GET_CODE (insn
) == JUMP_INSN
)
439 if (unroll_type
== UNROLL_COMPLETELY
)
441 /* Completely unrolling the loop: Delete the compare and branch at
442 the end (the last two instructions). This delete must done at the
443 very end of loop unrolling, to avoid problems with calls to
444 back_branch_in_range_p, which is called by find_splittable_regs.
445 All increments of splittable bivs/givs are changed to load constant
448 copy_start
= loop_start
;
450 /* Set insert_before to the instruction immediately after the JUMP_INSN
451 (or BARRIER), so that any NOTEs between the JUMP_INSN and the end of
452 the loop will be correctly handled by copy_loop_body. */
453 insert_before
= NEXT_INSN (last_loop_insn
);
455 /* Set copy_end to the insn before the jump at the end of the loop. */
456 if (GET_CODE (last_loop_insn
) == BARRIER
)
457 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
458 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
461 /* The instruction immediately before the JUMP_INSN is a compare
462 instruction which we do not want to copy. */
463 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
465 /* The instruction immediately before the JUMP_INSN may not be the
466 compare, so we must copy it. */
467 copy_end
= PREV_INSN (last_loop_insn
);
472 /* We currently can't unroll a loop if it doesn't end with a
473 JUMP_INSN. There would need to be a mechanism that recognizes
474 this case, and then inserts a jump after each loop body, which
475 jumps to after the last loop body. */
476 if (loop_dump_stream
)
477 fprintf (loop_dump_stream
,
478 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
482 else if (unroll_type
== UNROLL_MODULO
)
484 /* Partially unrolling the loop: The compare and branch at the end
485 (the last two instructions) must remain. Don't copy the compare
486 and branch instructions at the end of the loop. Insert the unrolled
487 code immediately before the compare/branch at the end so that the
488 code will fall through to them as before. */
490 copy_start
= loop_start
;
492 /* Set insert_before to the jump insn at the end of the loop.
493 Set copy_end to before the jump insn at the end of the loop. */
494 if (GET_CODE (last_loop_insn
) == BARRIER
)
496 insert_before
= PREV_INSN (last_loop_insn
);
497 copy_end
= PREV_INSN (insert_before
);
499 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
502 /* The instruction immediately before the JUMP_INSN is a compare
503 instruction which we do not want to copy or delete. */
504 insert_before
= PREV_INSN (last_loop_insn
);
505 copy_end
= PREV_INSN (insert_before
);
507 /* The instruction immediately before the JUMP_INSN may not be the
508 compare, so we must copy it. */
509 insert_before
= last_loop_insn
;
510 copy_end
= PREV_INSN (last_loop_insn
);
515 /* We currently can't unroll a loop if it doesn't end with a
516 JUMP_INSN. There would need to be a mechanism that recognizes
517 this case, and then inserts a jump after each loop body, which
518 jumps to after the last loop body. */
519 if (loop_dump_stream
)
520 fprintf (loop_dump_stream
,
521 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
527 /* Normal case: Must copy the compare and branch instructions at the
530 if (GET_CODE (last_loop_insn
) == BARRIER
)
532 /* Loop ends with an unconditional jump and a barrier.
533 Handle this like above, don't copy jump and barrier.
534 This is not strictly necessary, but doing so prevents generating
535 unconditional jumps to an immediately following label.
537 This will be corrected below if the target of this jump is
538 not the start_label. */
540 insert_before
= PREV_INSN (last_loop_insn
);
541 copy_end
= PREV_INSN (insert_before
);
543 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
545 /* Set insert_before to immediately after the JUMP_INSN, so that
546 NOTEs at the end of the loop will be correctly handled by
548 insert_before
= NEXT_INSN (last_loop_insn
);
549 copy_end
= last_loop_insn
;
553 /* We currently can't unroll a loop if it doesn't end with a
554 JUMP_INSN. There would need to be a mechanism that recognizes
555 this case, and then inserts a jump after each loop body, which
556 jumps to after the last loop body. */
557 if (loop_dump_stream
)
558 fprintf (loop_dump_stream
,
559 "Unrolling failure: loop does not end with a JUMP_INSN.\n");
563 /* If copying exit test branches because they can not be eliminated,
564 then must convert the fall through case of the branch to a jump past
565 the end of the loop. Create a label to emit after the loop and save
566 it for later use. Do not use the label after the loop, if any, since
567 it might be used by insns outside the loop, or there might be insns
568 added before it later by final_[bg]iv_value which must be after
569 the real exit label. */
570 exit_label
= gen_label_rtx ();
573 while (GET_CODE (insn
) != CODE_LABEL
&& GET_CODE (insn
) != JUMP_INSN
)
574 insn
= NEXT_INSN (insn
);
576 if (GET_CODE (insn
) == JUMP_INSN
)
578 /* The loop starts with a jump down to the exit condition test.
579 Start copying the loop after the barrier following this
581 copy_start
= NEXT_INSN (insn
);
583 /* Splitting induction variables doesn't work when the loop is
584 entered via a jump to the bottom, because then we end up doing
585 a comparison against a new register for a split variable, but
586 we did not execute the set insn for the new register because
587 it was skipped over. */
588 splitting_not_safe
= 1;
589 if (loop_dump_stream
)
590 fprintf (loop_dump_stream
,
591 "Splitting not safe, because loop not entered at top.\n");
594 copy_start
= loop_start
;
597 /* This should always be the first label in the loop. */
598 start_label
= NEXT_INSN (copy_start
);
599 /* There may be a line number note and/or a loop continue note here. */
600 while (GET_CODE (start_label
) == NOTE
)
601 start_label
= NEXT_INSN (start_label
);
602 if (GET_CODE (start_label
) != CODE_LABEL
)
604 /* This can happen as a result of jump threading. If the first insns in
605 the loop test the same condition as the loop's backward jump, or the
606 opposite condition, then the backward jump will be modified to point
607 to elsewhere, and the loop's start label is deleted.
609 This case currently can not be handled by the loop unrolling code. */
611 if (loop_dump_stream
)
612 fprintf (loop_dump_stream
,
613 "Unrolling failure: unknown insns between BEG note and loop label.\n");
616 if (LABEL_NAME (start_label
))
618 /* The jump optimization pass must have combined the original start label
619 with a named label for a goto. We can't unroll this case because
620 jumps which go to the named label must be handled differently than
621 jumps to the loop start, and it is impossible to differentiate them
623 if (loop_dump_stream
)
624 fprintf (loop_dump_stream
,
625 "Unrolling failure: loop start label is gone\n");
629 if (unroll_type
== UNROLL_NAIVE
630 && GET_CODE (last_loop_insn
) == BARRIER
631 && start_label
!= JUMP_LABEL (PREV_INSN (last_loop_insn
)))
633 /* In this case, we must copy the jump and barrier, because they will
634 not be converted to jumps to an immediately following label. */
636 insert_before
= NEXT_INSN (last_loop_insn
);
637 copy_end
= last_loop_insn
;
640 if (unroll_type
== UNROLL_NAIVE
641 && GET_CODE (last_loop_insn
) == JUMP_INSN
642 && start_label
!= JUMP_LABEL (last_loop_insn
))
644 /* ??? The loop ends with a conditional branch that does not branch back
645 to the loop start label. In this case, we must emit an unconditional
646 branch to the loop exit after emitting the final branch.
647 copy_loop_body does not have support for this currently, so we
648 give up. It doesn't seem worthwhile to unroll anyways since
649 unrolling would increase the number of branch instructions
651 if (loop_dump_stream
)
652 fprintf (loop_dump_stream
,
653 "Unrolling failure: final conditional branch not to loop start\n");
657 /* Allocate a translation table for the labels and insn numbers.
658 They will be filled in as we copy the insns in the loop. */
660 max_labelno
= max_label_num ();
661 max_insnno
= get_max_uid ();
663 map
= (struct inline_remap
*) alloca (sizeof (struct inline_remap
));
665 map
->integrating
= 0;
667 /* Allocate the label map. */
671 map
->label_map
= (rtx
*) alloca (max_labelno
* sizeof (rtx
));
673 local_label
= (char *) alloca (max_labelno
);
674 bzero (local_label
, max_labelno
);
679 /* Search the loop and mark all local labels, i.e. the ones which have to
680 be distinct labels when copied. For all labels which might be
681 non-local, set their label_map entries to point to themselves.
682 If they happen to be local their label_map entries will be overwritten
683 before the loop body is copied. The label_map entries for local labels
684 will be set to a different value each time the loop body is copied. */
686 for (insn
= copy_start
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
688 if (GET_CODE (insn
) == CODE_LABEL
)
689 local_label
[CODE_LABEL_NUMBER (insn
)] = 1;
690 else if (GET_CODE (insn
) == JUMP_INSN
)
692 if (JUMP_LABEL (insn
))
693 map
->label_map
[CODE_LABEL_NUMBER (JUMP_LABEL (insn
))]
695 else if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
696 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
698 rtx pat
= PATTERN (insn
);
699 int diff_vec_p
= GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
;
700 int len
= XVECLEN (pat
, diff_vec_p
);
703 for (i
= 0; i
< len
; i
++)
705 label
= XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0);
706 map
->label_map
[CODE_LABEL_NUMBER (label
)] = label
;
712 /* Allocate space for the insn map. */
714 map
->insn_map
= (rtx
*) alloca (max_insnno
* sizeof (rtx
));
716 /* Set this to zero, to indicate that we are doing loop unrolling,
717 not function inlining. */
718 map
->inline_target
= 0;
720 /* The register and constant maps depend on the number of registers
721 present, so the final maps can't be created until after
722 find_splittable_regs is called. However, they are needed for
723 preconditioning, so we create temporary maps when preconditioning
726 /* The preconditioning code may allocate two new pseudo registers. */
727 maxregnum
= max_reg_num ();
729 /* Allocate and zero out the splittable_regs and addr_combined_regs
730 arrays. These must be zeroed here because they will be used if
731 loop preconditioning is performed, and must be zero for that case.
733 It is safe to do this here, since the extra registers created by the
734 preconditioning code and find_splittable_regs will never be used
735 to access the splittable_regs[] and addr_combined_regs[] arrays. */
737 splittable_regs
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
738 bzero ((char *) splittable_regs
, maxregnum
* sizeof (rtx
));
739 splittable_regs_updates
= (int *) alloca (maxregnum
* sizeof (int));
740 bzero ((char *) splittable_regs_updates
, maxregnum
* sizeof (int));
742 = (struct induction
**) alloca (maxregnum
* sizeof (struct induction
*));
743 bzero ((char *) addr_combined_regs
, maxregnum
* sizeof (struct induction
*));
744 /* We must limit it to max_reg_before_loop, because only these pseudo
745 registers have valid regno_first_uid info. Any register created after
746 that is unlikely to be local to the loop anyways. */
747 local_regno
= (char *) alloca (max_reg_before_loop
);
748 bzero (local_regno
, max_reg_before_loop
);
750 /* Mark all local registers, i.e. the ones which are referenced only
752 if (INSN_UID (copy_end
) < max_uid_for_loop
)
754 int copy_start_luid
= INSN_LUID (copy_start
);
755 int copy_end_luid
= INSN_LUID (copy_end
);
757 /* If a register is used in the jump insn, we must not duplicate it
758 since it will also be used outside the loop. */
759 if (GET_CODE (copy_end
) == JUMP_INSN
)
761 /* If copy_start points to the NOTE that starts the loop, then we must
762 use the next luid, because invariant pseudo-regs moved out of the loop
763 have their lifetimes modified to start here, but they are not safe
765 if (copy_start
== loop_start
)
768 /* If a pseudo's lifetime is entirely contained within this loop, then we
769 can use a different pseudo in each unrolled copy of the loop. This
770 results in better code. */
771 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_reg_before_loop
; ++j
)
772 if (regno_first_uid
[j
] > 0 && regno_first_uid
[j
] <= max_uid_for_loop
773 && uid_luid
[regno_first_uid
[j
]] >= copy_start_luid
774 && regno_last_uid
[j
] > 0 && regno_last_uid
[j
] <= max_uid_for_loop
775 && uid_luid
[regno_last_uid
[j
]] <= copy_end_luid
)
777 /* However, we must also check for loop-carried dependencies.
778 If the value the pseudo has at the end of iteration X is
779 used by iteration X+1, then we can not use a different pseudo
780 for each unrolled copy of the loop. */
781 /* A pseudo is safe if regno_first_uid is a set, and this
782 set dominates all instructions from regno_first_uid to
784 /* ??? This check is simplistic. We would get better code if
785 this check was more sophisticated. */
786 if (set_dominates_use (j
, regno_first_uid
[j
], regno_last_uid
[j
],
787 copy_start
, copy_end
))
790 if (loop_dump_stream
)
793 fprintf (loop_dump_stream
, "Marked reg %d as local\n", j
);
795 fprintf (loop_dump_stream
, "Did not mark reg %d as local\n",
801 /* If this loop requires exit tests when unrolled, check to see if we
802 can precondition the loop so as to make the exit tests unnecessary.
803 Just like variable splitting, this is not safe if the loop is entered
804 via a jump to the bottom. Also, can not do this if no strength
805 reduce info, because precondition_loop_p uses this info. */
807 /* Must copy the loop body for preconditioning before the following
808 find_splittable_regs call since that will emit insns which need to
809 be after the preconditioned loop copies, but immediately before the
810 unrolled loop copies. */
812 /* Also, it is not safe to split induction variables for the preconditioned
813 copies of the loop body. If we split induction variables, then the code
814 assumes that each induction variable can be represented as a function
815 of its initial value and the loop iteration number. This is not true
816 in this case, because the last preconditioned copy of the loop body
817 could be any iteration from the first up to the `unroll_number-1'th,
818 depending on the initial value of the iteration variable. Therefore
819 we can not split induction variables here, because we can not calculate
820 their value. Hence, this code must occur before find_splittable_regs
823 if (unroll_type
== UNROLL_NAIVE
&& ! splitting_not_safe
&& strength_reduce_p
)
825 rtx initial_value
, final_value
, increment
;
827 if (precondition_loop_p (&initial_value
, &final_value
, &increment
,
828 loop_start
, loop_end
))
830 register rtx diff
, temp
;
831 enum machine_mode mode
;
833 int abs_inc
, neg_inc
;
835 map
->reg_map
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
837 map
->const_equiv_map
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
838 map
->const_age_map
= (unsigned *) alloca (maxregnum
839 * sizeof (unsigned));
840 map
->const_equiv_map_size
= maxregnum
;
841 global_const_equiv_map
= map
->const_equiv_map
;
842 global_const_equiv_map_size
= maxregnum
;
844 init_reg_map (map
, maxregnum
);
846 /* Limit loop unrolling to 4, since this will make 7 copies of
848 if (unroll_number
> 4)
851 /* Save the absolute value of the increment, and also whether or
852 not it is negative. */
854 abs_inc
= INTVAL (increment
);
863 /* Decide what mode to do these calculations in. Choose the larger
864 of final_value's mode and initial_value's mode, or a full-word if
865 both are constants. */
866 mode
= GET_MODE (final_value
);
867 if (mode
== VOIDmode
)
869 mode
= GET_MODE (initial_value
);
870 if (mode
== VOIDmode
)
873 else if (mode
!= GET_MODE (initial_value
)
874 && (GET_MODE_SIZE (mode
)
875 < GET_MODE_SIZE (GET_MODE (initial_value
))))
876 mode
= GET_MODE (initial_value
);
878 /* Calculate the difference between the final and initial values.
879 Final value may be a (plus (reg x) (const_int 1)) rtx.
880 Let the following cse pass simplify this if initial value is
883 We must copy the final and initial values here to avoid
884 improperly shared rtl. */
886 diff
= expand_binop (mode
, sub_optab
, copy_rtx (final_value
),
887 copy_rtx (initial_value
), NULL_RTX
, 0,
890 /* Now calculate (diff % (unroll * abs (increment))) by using an
892 diff
= expand_binop (GET_MODE (diff
), and_optab
, diff
,
893 GEN_INT (unroll_number
* abs_inc
- 1),
894 NULL_RTX
, 0, OPTAB_LIB_WIDEN
);
896 /* Now emit a sequence of branches to jump to the proper precond
899 labels
= (rtx
*) alloca (sizeof (rtx
) * unroll_number
);
900 for (i
= 0; i
< unroll_number
; i
++)
901 labels
[i
] = gen_label_rtx ();
903 /* Check for the case where the initial value is greater than or
904 equal to the final value. In that case, we want to execute
905 exactly one loop iteration. The code below will fail for this
906 case. This check does not apply if the loop has a NE
907 comparison at the end. */
909 if (loop_comparison_code
!= NE
)
911 emit_cmp_insn (initial_value
, final_value
, neg_inc
? LE
: GE
,
912 NULL_RTX
, mode
, 0, 0);
914 emit_jump_insn (gen_ble (labels
[1]));
916 emit_jump_insn (gen_bge (labels
[1]));
917 JUMP_LABEL (get_last_insn ()) = labels
[1];
918 LABEL_NUSES (labels
[1])++;
921 /* Assuming the unroll_number is 4, and the increment is 2, then
922 for a negative increment: for a positive increment:
923 diff = 0,1 precond 0 diff = 0,7 precond 0
924 diff = 2,3 precond 3 diff = 1,2 precond 1
925 diff = 4,5 precond 2 diff = 3,4 precond 2
926 diff = 6,7 precond 1 diff = 5,6 precond 3 */
928 /* We only need to emit (unroll_number - 1) branches here, the
929 last case just falls through to the following code. */
931 /* ??? This would give better code if we emitted a tree of branches
932 instead of the current linear list of branches. */
934 for (i
= 0; i
< unroll_number
- 1; i
++)
937 enum rtx_code cmp_code
;
939 /* For negative increments, must invert the constant compared
940 against, except when comparing against zero. */
948 cmp_const
= unroll_number
- i
;
957 emit_cmp_insn (diff
, GEN_INT (abs_inc
* cmp_const
),
958 cmp_code
, NULL_RTX
, mode
, 0, 0);
961 emit_jump_insn (gen_beq (labels
[i
]));
963 emit_jump_insn (gen_bge (labels
[i
]));
965 emit_jump_insn (gen_ble (labels
[i
]));
966 JUMP_LABEL (get_last_insn ()) = labels
[i
];
967 LABEL_NUSES (labels
[i
])++;
970 /* If the increment is greater than one, then we need another branch,
971 to handle other cases equivalent to 0. */
973 /* ??? This should be merged into the code above somehow to help
974 simplify the code here, and reduce the number of branches emitted.
975 For the negative increment case, the branch here could easily
976 be merged with the `0' case branch above. For the positive
977 increment case, it is not clear how this can be simplified. */
982 enum rtx_code cmp_code
;
986 cmp_const
= abs_inc
- 1;
991 cmp_const
= abs_inc
* (unroll_number
- 1) + 1;
995 emit_cmp_insn (diff
, GEN_INT (cmp_const
), cmp_code
, NULL_RTX
,
999 emit_jump_insn (gen_ble (labels
[0]));
1001 emit_jump_insn (gen_bge (labels
[0]));
1002 JUMP_LABEL (get_last_insn ()) = labels
[0];
1003 LABEL_NUSES (labels
[0])++;
1006 sequence
= gen_sequence ();
1008 emit_insn_before (sequence
, loop_start
);
1010 /* Only the last copy of the loop body here needs the exit
1011 test, so set copy_end to exclude the compare/branch here,
1012 and then reset it inside the loop when get to the last
1015 if (GET_CODE (last_loop_insn
) == BARRIER
)
1016 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1017 else if (GET_CODE (last_loop_insn
) == JUMP_INSN
)
1020 /* The immediately preceding insn is a compare which we do not
1022 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1024 /* The immediately preceding insn may not be a compare, so we
1026 copy_end
= PREV_INSN (last_loop_insn
);
1032 for (i
= 1; i
< unroll_number
; i
++)
1034 emit_label_after (labels
[unroll_number
- i
],
1035 PREV_INSN (loop_start
));
1037 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1038 bzero ((char *) map
->const_equiv_map
, maxregnum
* sizeof (rtx
));
1039 bzero ((char *) map
->const_age_map
,
1040 maxregnum
* sizeof (unsigned));
1043 for (j
= 0; j
< max_labelno
; j
++)
1045 map
->label_map
[j
] = gen_label_rtx ();
1047 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_reg_before_loop
; j
++)
1049 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1051 /* The last copy needs the compare/branch insns at the end,
1052 so reset copy_end here if the loop ends with a conditional
1055 if (i
== unroll_number
- 1)
1057 if (GET_CODE (last_loop_insn
) == BARRIER
)
1058 copy_end
= PREV_INSN (PREV_INSN (last_loop_insn
));
1060 copy_end
= last_loop_insn
;
1063 /* None of the copies are the `last_iteration', so just
1064 pass zero for that parameter. */
1065 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, 0,
1066 unroll_type
, start_label
, loop_end
,
1067 loop_start
, copy_end
);
1069 emit_label_after (labels
[0], PREV_INSN (loop_start
));
1071 if (GET_CODE (last_loop_insn
) == BARRIER
)
1073 insert_before
= PREV_INSN (last_loop_insn
);
1074 copy_end
= PREV_INSN (insert_before
);
1079 /* The immediately preceding insn is a compare which we do not
1081 insert_before
= PREV_INSN (last_loop_insn
);
1082 copy_end
= PREV_INSN (insert_before
);
1084 /* The immediately preceding insn may not be a compare, so we
1086 insert_before
= last_loop_insn
;
1087 copy_end
= PREV_INSN (last_loop_insn
);
1091 /* Set unroll type to MODULO now. */
1092 unroll_type
= UNROLL_MODULO
;
1093 loop_preconditioned
= 1;
1097 /* If reach here, and the loop type is UNROLL_NAIVE, then don't unroll
1098 the loop unless all loops are being unrolled. */
1099 if (unroll_type
== UNROLL_NAIVE
&& ! flag_unroll_all_loops
)
1101 if (loop_dump_stream
)
1102 fprintf (loop_dump_stream
, "Unrolling failure: Naive unrolling not being done.\n");
1106 /* At this point, we are guaranteed to unroll the loop. */
1108 /* For each biv and giv, determine whether it can be safely split into
1109 a different variable for each unrolled copy of the loop body.
1110 We precalculate and save this info here, since computing it is
1113 Do this before deleting any instructions from the loop, so that
1114 back_branch_in_range_p will work correctly. */
1116 if (splitting_not_safe
)
1119 temp
= find_splittable_regs (unroll_type
, loop_start
, loop_end
,
1120 end_insert_before
, unroll_number
);
1122 /* find_splittable_regs may have created some new registers, so must
1123 reallocate the reg_map with the new larger size, and must realloc
1124 the constant maps also. */
1126 maxregnum
= max_reg_num ();
1127 map
->reg_map
= (rtx
*) alloca (maxregnum
* sizeof (rtx
));
1129 init_reg_map (map
, maxregnum
);
1131 /* Space is needed in some of the map for new registers, so new_maxregnum
1132 is an (over)estimate of how many registers will exist at the end. */
1133 new_maxregnum
= maxregnum
+ (temp
* unroll_number
* 2);
1135 /* Must realloc space for the constant maps, because the number of registers
1136 may have changed. */
1138 map
->const_equiv_map
= (rtx
*) alloca (new_maxregnum
* sizeof (rtx
));
1139 map
->const_age_map
= (unsigned *) alloca (new_maxregnum
* sizeof (unsigned));
1141 map
->const_equiv_map_size
= new_maxregnum
;
1142 global_const_equiv_map
= map
->const_equiv_map
;
1143 global_const_equiv_map_size
= new_maxregnum
;
1145 /* Search the list of bivs and givs to find ones which need to be remapped
1146 when split, and set their reg_map entry appropriately. */
1148 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
1150 if (REGNO (bl
->biv
->src_reg
) != bl
->regno
)
1151 map
->reg_map
[bl
->regno
] = bl
->biv
->src_reg
;
1153 /* Currently, non-reduced/final-value givs are never split. */
1154 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
1155 if (REGNO (v
->src_reg
) != bl
->regno
)
1156 map
->reg_map
[REGNO (v
->dest_reg
)] = v
->src_reg
;
1160 /* Use our current register alignment and pointer flags. */
1161 map
->regno_pointer_flag
= regno_pointer_flag
;
1162 map
->regno_pointer_align
= regno_pointer_align
;
1164 /* If the loop is being partially unrolled, and the iteration variables
1165 are being split, and are being renamed for the split, then must fix up
1166 the compare/jump instruction at the end of the loop to refer to the new
1167 registers. This compare isn't copied, so the registers used in it
1168 will never be replaced if it isn't done here. */
1170 if (unroll_type
== UNROLL_MODULO
)
1172 insn
= NEXT_INSN (copy_end
);
1173 if (GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
)
1174 PATTERN (insn
) = remap_split_bivs (PATTERN (insn
));
1177 /* For unroll_number - 1 times, make a copy of each instruction
1178 between copy_start and copy_end, and insert these new instructions
1179 before the end of the loop. */
1181 for (i
= 0; i
< unroll_number
; i
++)
1183 bzero ((char *) map
->insn_map
, max_insnno
* sizeof (rtx
));
1184 bzero ((char *) map
->const_equiv_map
, new_maxregnum
* sizeof (rtx
));
1185 bzero ((char *) map
->const_age_map
, new_maxregnum
* sizeof (unsigned));
1188 for (j
= 0; j
< max_labelno
; j
++)
1190 map
->label_map
[j
] = gen_label_rtx ();
1192 for (j
= FIRST_PSEUDO_REGISTER
; j
< max_reg_before_loop
; j
++)
1194 map
->reg_map
[j
] = gen_reg_rtx (GET_MODE (regno_reg_rtx
[j
]));
1196 /* If loop starts with a branch to the test, then fix it so that
1197 it points to the test of the first unrolled copy of the loop. */
1198 if (i
== 0 && loop_start
!= copy_start
)
1200 insn
= PREV_INSN (copy_start
);
1201 pattern
= PATTERN (insn
);
1203 tem
= map
->label_map
[CODE_LABEL_NUMBER
1204 (XEXP (SET_SRC (pattern
), 0))];
1205 SET_SRC (pattern
) = gen_rtx (LABEL_REF
, VOIDmode
, tem
);
1207 /* Set the jump label so that it can be used by later loop unrolling
1209 JUMP_LABEL (insn
) = tem
;
1210 LABEL_NUSES (tem
)++;
1213 copy_loop_body (copy_start
, copy_end
, map
, exit_label
,
1214 i
== unroll_number
- 1, unroll_type
, start_label
,
1215 loop_end
, insert_before
, insert_before
);
1218 /* Before deleting any insns, emit a CODE_LABEL immediately after the last
1219 insn to be deleted. This prevents any runaway delete_insn call from
1220 more insns that it should, as it always stops at a CODE_LABEL. */
1222 /* Delete the compare and branch at the end of the loop if completely
1223 unrolling the loop. Deleting the backward branch at the end also
1224 deletes the code label at the start of the loop. This is done at
1225 the very end to avoid problems with back_branch_in_range_p. */
1227 if (unroll_type
== UNROLL_COMPLETELY
)
1228 safety_label
= emit_label_after (gen_label_rtx (), last_loop_insn
);
1230 safety_label
= emit_label_after (gen_label_rtx (), copy_end
);
1232 /* Delete all of the original loop instructions. Don't delete the
1233 LOOP_BEG note, or the first code label in the loop. */
1235 insn
= NEXT_INSN (copy_start
);
1236 while (insn
!= safety_label
)
1238 if (insn
!= start_label
)
1239 insn
= delete_insn (insn
);
1241 insn
= NEXT_INSN (insn
);
1244 /* Can now delete the 'safety' label emitted to protect us from runaway
1245 delete_insn calls. */
1246 if (INSN_DELETED_P (safety_label
))
1248 delete_insn (safety_label
);
1250 /* If exit_label exists, emit it after the loop. Doing the emit here
1251 forces it to have a higher INSN_UID than any insn in the unrolled loop.
1252 This is needed so that mostly_true_jump in reorg.c will treat jumps
1253 to this loop end label correctly, i.e. predict that they are usually
1256 emit_label_after (exit_label
, loop_end
);
1259 /* Return true if the loop can be safely, and profitably, preconditioned
1260 so that the unrolled copies of the loop body don't need exit tests.
1262 This only works if final_value, initial_value and increment can be
1263 determined, and if increment is a constant power of 2.
1264 If increment is not a power of 2, then the preconditioning modulo
1265 operation would require a real modulo instead of a boolean AND, and this
1266 is not considered `profitable'. */
1268 /* ??? If the loop is known to be executed very many times, or the machine
1269 has a very cheap divide instruction, then preconditioning is a win even
1270 when the increment is not a power of 2. Use RTX_COST to compute
1271 whether divide is cheap. */
1274 precondition_loop_p (initial_value
, final_value
, increment
, loop_start
,
1276 rtx
*initial_value
, *final_value
, *increment
;
1277 rtx loop_start
, loop_end
;
1280 if (loop_n_iterations
> 0)
1282 *initial_value
= const0_rtx
;
1283 *increment
= const1_rtx
;
1284 *final_value
= GEN_INT (loop_n_iterations
);
1286 if (loop_dump_stream
)
1287 fprintf (loop_dump_stream
,
1288 "Preconditioning: Success, number of iterations known, %d.\n",
1293 if (loop_initial_value
== 0)
1295 if (loop_dump_stream
)
1296 fprintf (loop_dump_stream
,
1297 "Preconditioning: Could not find initial value.\n");
1300 else if (loop_increment
== 0)
1302 if (loop_dump_stream
)
1303 fprintf (loop_dump_stream
,
1304 "Preconditioning: Could not find increment value.\n");
1307 else if (GET_CODE (loop_increment
) != CONST_INT
)
1309 if (loop_dump_stream
)
1310 fprintf (loop_dump_stream
,
1311 "Preconditioning: Increment not a constant.\n");
1314 else if ((exact_log2 (INTVAL (loop_increment
)) < 0)
1315 && (exact_log2 (- INTVAL (loop_increment
)) < 0))
1317 if (loop_dump_stream
)
1318 fprintf (loop_dump_stream
,
1319 "Preconditioning: Increment not a constant power of 2.\n");
1323 /* Unsigned_compare and compare_dir can be ignored here, since they do
1324 not matter for preconditioning. */
1326 if (loop_final_value
== 0)
1328 if (loop_dump_stream
)
1329 fprintf (loop_dump_stream
,
1330 "Preconditioning: EQ comparison loop.\n");
1334 /* Must ensure that final_value is invariant, so call invariant_p to
1335 check. Before doing so, must check regno against max_reg_before_loop
1336 to make sure that the register is in the range covered by invariant_p.
1337 If it isn't, then it is most likely a biv/giv which by definition are
1339 if ((GET_CODE (loop_final_value
) == REG
1340 && REGNO (loop_final_value
) >= max_reg_before_loop
)
1341 || (GET_CODE (loop_final_value
) == PLUS
1342 && REGNO (XEXP (loop_final_value
, 0)) >= max_reg_before_loop
)
1343 || ! invariant_p (loop_final_value
))
1345 if (loop_dump_stream
)
1346 fprintf (loop_dump_stream
,
1347 "Preconditioning: Final value not invariant.\n");
1351 /* Fail for floating point values, since the caller of this function
1352 does not have code to deal with them. */
1353 if (GET_MODE_CLASS (GET_MODE (loop_final_value
)) == MODE_FLOAT
1354 || GET_MODE_CLASS (GET_MODE (loop_initial_value
)) == MODE_FLOAT
)
1356 if (loop_dump_stream
)
1357 fprintf (loop_dump_stream
,
1358 "Preconditioning: Floating point final or initial value.\n");
1362 /* Now set initial_value to be the iteration_var, since that may be a
1363 simpler expression, and is guaranteed to be correct if all of the
1364 above tests succeed.
1366 We can not use the initial_value as calculated, because it will be
1367 one too small for loops of the form "while (i-- > 0)". We can not
1368 emit code before the loop_skip_over insns to fix this problem as this
1369 will then give a number one too large for loops of the form
1372 Note that all loops that reach here are entered at the top, because
1373 this function is not called if the loop starts with a jump. */
1375 /* Fail if loop_iteration_var is not live before loop_start, since we need
1376 to test its value in the preconditioning code. */
1378 if (uid_luid
[regno_first_uid
[REGNO (loop_iteration_var
)]]
1379 > INSN_LUID (loop_start
))
1381 if (loop_dump_stream
)
1382 fprintf (loop_dump_stream
,
1383 "Preconditioning: Iteration var not live before loop start.\n");
1387 *initial_value
= loop_iteration_var
;
1388 *increment
= loop_increment
;
1389 *final_value
= loop_final_value
;
1392 if (loop_dump_stream
)
1393 fprintf (loop_dump_stream
, "Preconditioning: Successful.\n");
1398 /* All pseudo-registers must be mapped to themselves. Two hard registers
1399 must be mapped, VIRTUAL_STACK_VARS_REGNUM and VIRTUAL_INCOMING_ARGS_
1400 REGNUM, to avoid function-inlining specific conversions of these
1401 registers. All other hard regs can not be mapped because they may be
1406 init_reg_map (map
, maxregnum
)
1407 struct inline_remap
*map
;
1412 for (i
= maxregnum
- 1; i
> LAST_VIRTUAL_REGISTER
; i
--)
1413 map
->reg_map
[i
] = regno_reg_rtx
[i
];
1414 /* Just clear the rest of the entries. */
1415 for (i
= LAST_VIRTUAL_REGISTER
; i
>= 0; i
--)
1416 map
->reg_map
[i
] = 0;
1418 map
->reg_map
[VIRTUAL_STACK_VARS_REGNUM
]
1419 = regno_reg_rtx
[VIRTUAL_STACK_VARS_REGNUM
];
1420 map
->reg_map
[VIRTUAL_INCOMING_ARGS_REGNUM
]
1421 = regno_reg_rtx
[VIRTUAL_INCOMING_ARGS_REGNUM
];
1424 /* Strength-reduction will often emit code for optimized biv/givs which
1425 calculates their value in a temporary register, and then copies the result
1426 to the iv. This procedure reconstructs the pattern computing the iv;
1427 verifying that all operands are of the proper form.
1429 The return value is the amount that the giv is incremented by. */
1432 calculate_giv_inc (pattern
, src_insn
, regno
)
1433 rtx pattern
, src_insn
;
1437 rtx increment_total
= 0;
1441 /* Verify that we have an increment insn here. First check for a plus
1442 as the set source. */
1443 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1445 /* SR sometimes computes the new giv value in a temp, then copies it
1447 src_insn
= PREV_INSN (src_insn
);
1448 pattern
= PATTERN (src_insn
);
1449 if (GET_CODE (SET_SRC (pattern
)) != PLUS
)
1452 /* The last insn emitted is not needed, so delete it to avoid confusing
1453 the second cse pass. This insn sets the giv unnecessarily. */
1454 delete_insn (get_last_insn ());
1457 /* Verify that we have a constant as the second operand of the plus. */
1458 increment
= XEXP (SET_SRC (pattern
), 1);
1459 if (GET_CODE (increment
) != CONST_INT
)
1461 /* SR sometimes puts the constant in a register, especially if it is
1462 too big to be an add immed operand. */
1463 src_insn
= PREV_INSN (src_insn
);
1464 increment
= SET_SRC (PATTERN (src_insn
));
1466 /* SR may have used LO_SUM to compute the constant if it is too large
1467 for a load immed operand. In this case, the constant is in operand
1468 one of the LO_SUM rtx. */
1469 if (GET_CODE (increment
) == LO_SUM
)
1470 increment
= XEXP (increment
, 1);
1471 else if (GET_CODE (increment
) == IOR
1472 || GET_CODE (increment
) == ASHIFT
)
1474 /* The rs6000 port loads some constants with IOR.
1475 The alpha port loads some constants with ASHIFT. */
1476 rtx second_part
= XEXP (increment
, 1);
1477 enum rtx_code code
= GET_CODE (increment
);
1479 src_insn
= PREV_INSN (src_insn
);
1480 increment
= SET_SRC (PATTERN (src_insn
));
1481 /* Don't need the last insn anymore. */
1482 delete_insn (get_last_insn ());
1484 if (GET_CODE (second_part
) != CONST_INT
1485 || GET_CODE (increment
) != CONST_INT
)
1489 increment
= GEN_INT (INTVAL (increment
) | INTVAL (second_part
));
1491 increment
= GEN_INT (INTVAL (increment
) << INTVAL (second_part
));
1494 if (GET_CODE (increment
) != CONST_INT
)
1497 /* The insn loading the constant into a register is no longer needed,
1499 delete_insn (get_last_insn ());
1502 if (increment_total
)
1503 increment_total
= GEN_INT (INTVAL (increment_total
) + INTVAL (increment
));
1505 increment_total
= increment
;
1507 /* Check that the source register is the same as the register we expected
1508 to see as the source. If not, something is seriously wrong. */
1509 if (GET_CODE (XEXP (SET_SRC (pattern
), 0)) != REG
1510 || REGNO (XEXP (SET_SRC (pattern
), 0)) != regno
)
1512 /* Some machines (e.g. the romp), may emit two add instructions for
1513 certain constants, so lets try looking for another add immediately
1514 before this one if we have only seen one add insn so far. */
1520 src_insn
= PREV_INSN (src_insn
);
1521 pattern
= PATTERN (src_insn
);
1523 delete_insn (get_last_insn ());
1531 return increment_total
;
1534 /* Copy REG_NOTES, except for insn references, because not all insn_map
1535 entries are valid yet. We do need to copy registers now though, because
1536 the reg_map entries can change during copying. */
1539 initial_reg_note_copy (notes
, map
)
1541 struct inline_remap
*map
;
1548 copy
= rtx_alloc (GET_CODE (notes
));
1549 PUT_MODE (copy
, GET_MODE (notes
));
1551 if (GET_CODE (notes
) == EXPR_LIST
)
1552 XEXP (copy
, 0) = copy_rtx_and_substitute (XEXP (notes
, 0), map
);
1553 else if (GET_CODE (notes
) == INSN_LIST
)
1554 /* Don't substitute for these yet. */
1555 XEXP (copy
, 0) = XEXP (notes
, 0);
1559 XEXP (copy
, 1) = initial_reg_note_copy (XEXP (notes
, 1), map
);
1564 /* Fixup insn references in copied REG_NOTES. */
1567 final_reg_note_copy (notes
, map
)
1569 struct inline_remap
*map
;
1573 for (note
= notes
; note
; note
= XEXP (note
, 1))
1574 if (GET_CODE (note
) == INSN_LIST
)
1575 XEXP (note
, 0) = map
->insn_map
[INSN_UID (XEXP (note
, 0))];
1578 /* Copy each instruction in the loop, substituting from map as appropriate.
1579 This is very similar to a loop in expand_inline_function. */
1582 copy_loop_body (copy_start
, copy_end
, map
, exit_label
, last_iteration
,
1583 unroll_type
, start_label
, loop_end
, insert_before
,
1585 rtx copy_start
, copy_end
;
1586 struct inline_remap
*map
;
1589 enum unroll_types unroll_type
;
1590 rtx start_label
, loop_end
, insert_before
, copy_notes_from
;
1594 int dest_reg_was_split
, i
;
1596 rtx final_label
= 0;
1597 rtx giv_inc
, giv_dest_reg
, giv_src_reg
;
1599 /* If this isn't the last iteration, then map any references to the
1600 start_label to final_label. Final label will then be emitted immediately
1601 after the end of this loop body if it was ever used.
1603 If this is the last iteration, then map references to the start_label
1605 if (! last_iteration
)
1607 final_label
= gen_label_rtx ();
1608 map
->label_map
[CODE_LABEL_NUMBER (start_label
)] = final_label
;
1611 map
->label_map
[CODE_LABEL_NUMBER (start_label
)] = start_label
;
1618 insn
= NEXT_INSN (insn
);
1620 map
->orig_asm_operands_vector
= 0;
1622 switch (GET_CODE (insn
))
1625 pattern
= PATTERN (insn
);
1629 /* Check to see if this is a giv that has been combined with
1630 some split address givs. (Combined in the sense that
1631 `combine_givs' in loop.c has put two givs in the same register.)
1632 In this case, we must search all givs based on the same biv to
1633 find the address givs. Then split the address givs.
1634 Do this before splitting the giv, since that may map the
1635 SET_DEST to a new register. */
1637 if (GET_CODE (pattern
) == SET
1638 && GET_CODE (SET_DEST (pattern
)) == REG
1639 && addr_combined_regs
[REGNO (SET_DEST (pattern
))])
1641 struct iv_class
*bl
;
1642 struct induction
*v
, *tv
;
1643 int regno
= REGNO (SET_DEST (pattern
));
1645 v
= addr_combined_regs
[REGNO (SET_DEST (pattern
))];
1646 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
1648 /* Although the giv_inc amount is not needed here, we must call
1649 calculate_giv_inc here since it might try to delete the
1650 last insn emitted. If we wait until later to call it,
1651 we might accidentally delete insns generated immediately
1652 below by emit_unrolled_add. */
1654 giv_inc
= calculate_giv_inc (pattern
, insn
, regno
);
1656 /* Now find all address giv's that were combined with this
1658 for (tv
= bl
->giv
; tv
; tv
= tv
->next_iv
)
1659 if (tv
->giv_type
== DEST_ADDR
&& tv
->same
== v
)
1663 /* If this DEST_ADDR giv was not split, then ignore it. */
1664 if (*tv
->location
!= tv
->dest_reg
)
1667 /* Scale this_giv_inc if the multiplicative factors of
1668 the two givs are different. */
1669 this_giv_inc
= INTVAL (giv_inc
);
1670 if (tv
->mult_val
!= v
->mult_val
)
1671 this_giv_inc
= (this_giv_inc
/ INTVAL (v
->mult_val
)
1672 * INTVAL (tv
->mult_val
));
1674 tv
->dest_reg
= plus_constant (tv
->dest_reg
, this_giv_inc
);
1675 *tv
->location
= tv
->dest_reg
;
1677 if (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)
1679 /* Must emit an insn to increment the split address
1680 giv. Add in the const_adjust field in case there
1681 was a constant eliminated from the address. */
1682 rtx value
, dest_reg
;
1684 /* tv->dest_reg will be either a bare register,
1685 or else a register plus a constant. */
1686 if (GET_CODE (tv
->dest_reg
) == REG
)
1687 dest_reg
= tv
->dest_reg
;
1689 dest_reg
= XEXP (tv
->dest_reg
, 0);
1691 /* Check for shared address givs, and avoid
1692 incrementing the shared pseudo reg more than
1694 if (! tv
->same_insn
)
1696 /* tv->dest_reg may actually be a (PLUS (REG)
1697 (CONST)) here, so we must call plus_constant
1698 to add the const_adjust amount before calling
1699 emit_unrolled_add below. */
1700 value
= plus_constant (tv
->dest_reg
,
1703 /* The constant could be too large for an add
1704 immediate, so can't directly emit an insn
1706 emit_unrolled_add (dest_reg
, XEXP (value
, 0),
1710 /* Reset the giv to be just the register again, in case
1711 it is used after the set we have just emitted.
1712 We must subtract the const_adjust factor added in
1714 tv
->dest_reg
= plus_constant (dest_reg
,
1715 - tv
->const_adjust
);
1716 *tv
->location
= tv
->dest_reg
;
1721 /* If this is a setting of a splittable variable, then determine
1722 how to split the variable, create a new set based on this split,
1723 and set up the reg_map so that later uses of the variable will
1724 use the new split variable. */
1726 dest_reg_was_split
= 0;
1728 if (GET_CODE (pattern
) == SET
1729 && GET_CODE (SET_DEST (pattern
)) == REG
1730 && splittable_regs
[REGNO (SET_DEST (pattern
))])
1732 int regno
= REGNO (SET_DEST (pattern
));
1734 dest_reg_was_split
= 1;
1736 /* Compute the increment value for the giv, if it wasn't
1737 already computed above. */
1740 giv_inc
= calculate_giv_inc (pattern
, insn
, regno
);
1741 giv_dest_reg
= SET_DEST (pattern
);
1742 giv_src_reg
= SET_DEST (pattern
);
1744 if (unroll_type
== UNROLL_COMPLETELY
)
1746 /* Completely unrolling the loop. Set the induction
1747 variable to a known constant value. */
1749 /* The value in splittable_regs may be an invariant
1750 value, so we must use plus_constant here. */
1751 splittable_regs
[regno
]
1752 = plus_constant (splittable_regs
[regno
], INTVAL (giv_inc
));
1754 if (GET_CODE (splittable_regs
[regno
]) == PLUS
)
1756 giv_src_reg
= XEXP (splittable_regs
[regno
], 0);
1757 giv_inc
= XEXP (splittable_regs
[regno
], 1);
1761 /* The splittable_regs value must be a REG or a
1762 CONST_INT, so put the entire value in the giv_src_reg
1764 giv_src_reg
= splittable_regs
[regno
];
1765 giv_inc
= const0_rtx
;
1770 /* Partially unrolling loop. Create a new pseudo
1771 register for the iteration variable, and set it to
1772 be a constant plus the original register. Except
1773 on the last iteration, when the result has to
1774 go back into the original iteration var register. */
1776 /* Handle bivs which must be mapped to a new register
1777 when split. This happens for bivs which need their
1778 final value set before loop entry. The new register
1779 for the biv was stored in the biv's first struct
1780 induction entry by find_splittable_regs. */
1782 if (regno
< max_reg_before_loop
1783 && reg_iv_type
[regno
] == BASIC_INDUCT
)
1785 giv_src_reg
= reg_biv_class
[regno
]->biv
->src_reg
;
1786 giv_dest_reg
= giv_src_reg
;
1790 /* If non-reduced/final-value givs were split, then
1791 this would have to remap those givs also. See
1792 find_splittable_regs. */
1795 splittable_regs
[regno
]
1796 = GEN_INT (INTVAL (giv_inc
)
1797 + INTVAL (splittable_regs
[regno
]));
1798 giv_inc
= splittable_regs
[regno
];
1800 /* Now split the induction variable by changing the dest
1801 of this insn to a new register, and setting its
1802 reg_map entry to point to this new register.
1804 If this is the last iteration, and this is the last insn
1805 that will update the iv, then reuse the original dest,
1806 to ensure that the iv will have the proper value when
1807 the loop exits or repeats.
1809 Using splittable_regs_updates here like this is safe,
1810 because it can only be greater than one if all
1811 instructions modifying the iv are always executed in
1814 if (! last_iteration
1815 || (splittable_regs_updates
[regno
]-- != 1))
1817 tem
= gen_reg_rtx (GET_MODE (giv_src_reg
));
1819 map
->reg_map
[regno
] = tem
;
1822 map
->reg_map
[regno
] = giv_src_reg
;
1825 /* The constant being added could be too large for an add
1826 immediate, so can't directly emit an insn here. */
1827 emit_unrolled_add (giv_dest_reg
, giv_src_reg
, giv_inc
);
1828 copy
= get_last_insn ();
1829 pattern
= PATTERN (copy
);
1833 pattern
= copy_rtx_and_substitute (pattern
, map
);
1834 copy
= emit_insn (pattern
);
1836 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1839 /* If this insn is setting CC0, it may need to look at
1840 the insn that uses CC0 to see what type of insn it is.
1841 In that case, the call to recog via validate_change will
1842 fail. So don't substitute constants here. Instead,
1843 do it when we emit the following insn.
1845 For example, see the pyr.md file. That machine has signed and
1846 unsigned compares. The compare patterns must check the
1847 following branch insn to see which what kind of compare to
1850 If the previous insn set CC0, substitute constants on it as
1852 if (sets_cc0_p (PATTERN (copy
)) != 0)
1857 try_constants (cc0_insn
, map
);
1859 try_constants (copy
, map
);
1862 try_constants (copy
, map
);
1865 /* Make split induction variable constants `permanent' since we
1866 know there are no backward branches across iteration variable
1867 settings which would invalidate this. */
1868 if (dest_reg_was_split
)
1870 int regno
= REGNO (SET_DEST (pattern
));
1872 if (regno
< map
->const_equiv_map_size
1873 && map
->const_age_map
[regno
] == map
->const_age
)
1874 map
->const_age_map
[regno
] = -1;
1879 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
);
1880 copy
= emit_jump_insn (pattern
);
1881 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
1883 if (JUMP_LABEL (insn
) == start_label
&& insn
== copy_end
1884 && ! last_iteration
)
1886 /* This is a branch to the beginning of the loop; this is the
1887 last insn being copied; and this is not the last iteration.
1888 In this case, we want to change the original fall through
1889 case to be a branch past the end of the loop, and the
1890 original jump label case to fall_through. */
1892 if (invert_exp (pattern
, copy
))
1894 if (! redirect_exp (&pattern
,
1895 map
->label_map
[CODE_LABEL_NUMBER
1896 (JUMP_LABEL (insn
))],
1903 rtx lab
= gen_label_rtx ();
1904 /* Can't do it by reversing the jump (probably because we
1905 couldn't reverse the conditions), so emit a new
1906 jump_insn after COPY, and redirect the jump around
1908 jmp
= emit_jump_insn_after (gen_jump (exit_label
), copy
);
1909 jmp
= emit_barrier_after (jmp
);
1910 emit_label_after (lab
, jmp
);
1911 LABEL_NUSES (lab
) = 0;
1912 if (! redirect_exp (&pattern
,
1913 map
->label_map
[CODE_LABEL_NUMBER
1914 (JUMP_LABEL (insn
))],
1922 try_constants (cc0_insn
, map
);
1925 try_constants (copy
, map
);
1927 /* Set the jump label of COPY correctly to avoid problems with
1928 later passes of unroll_loop, if INSN had jump label set. */
1929 if (JUMP_LABEL (insn
))
1933 /* Can't use the label_map for every insn, since this may be
1934 the backward branch, and hence the label was not mapped. */
1935 if (GET_CODE (pattern
) == SET
)
1937 tem
= SET_SRC (pattern
);
1938 if (GET_CODE (tem
) == LABEL_REF
)
1939 label
= XEXP (tem
, 0);
1940 else if (GET_CODE (tem
) == IF_THEN_ELSE
)
1942 if (XEXP (tem
, 1) != pc_rtx
)
1943 label
= XEXP (XEXP (tem
, 1), 0);
1945 label
= XEXP (XEXP (tem
, 2), 0);
1949 if (label
&& GET_CODE (label
) == CODE_LABEL
)
1950 JUMP_LABEL (copy
) = label
;
1953 /* An unrecognizable jump insn, probably the entry jump
1954 for a switch statement. This label must have been mapped,
1955 so just use the label_map to get the new jump label. */
1957 = map
->label_map
[CODE_LABEL_NUMBER (JUMP_LABEL (insn
))];
1960 /* If this is a non-local jump, then must increase the label
1961 use count so that the label will not be deleted when the
1962 original jump is deleted. */
1963 LABEL_NUSES (JUMP_LABEL (copy
))++;
1965 else if (GET_CODE (PATTERN (copy
)) == ADDR_VEC
1966 || GET_CODE (PATTERN (copy
)) == ADDR_DIFF_VEC
)
1968 rtx pat
= PATTERN (copy
);
1969 int diff_vec_p
= GET_CODE (pat
) == ADDR_DIFF_VEC
;
1970 int len
= XVECLEN (pat
, diff_vec_p
);
1973 for (i
= 0; i
< len
; i
++)
1974 LABEL_NUSES (XEXP (XVECEXP (pat
, diff_vec_p
, i
), 0))++;
1977 /* If this used to be a conditional jump insn but whose branch
1978 direction is now known, we must do something special. */
1979 if (condjump_p (insn
) && !simplejump_p (insn
) && map
->last_pc_value
)
1982 /* The previous insn set cc0 for us. So delete it. */
1983 delete_insn (PREV_INSN (copy
));
1986 /* If this is now a no-op, delete it. */
1987 if (map
->last_pc_value
== pc_rtx
)
1989 /* Don't let delete_insn delete the label referenced here,
1990 because we might possibly need it later for some other
1991 instruction in the loop. */
1992 if (JUMP_LABEL (copy
))
1993 LABEL_NUSES (JUMP_LABEL (copy
))++;
1995 if (JUMP_LABEL (copy
))
1996 LABEL_NUSES (JUMP_LABEL (copy
))--;
2000 /* Otherwise, this is unconditional jump so we must put a
2001 BARRIER after it. We could do some dead code elimination
2002 here, but jump.c will do it just as well. */
2008 pattern
= copy_rtx_and_substitute (PATTERN (insn
), map
);
2009 copy
= emit_call_insn (pattern
);
2010 REG_NOTES (copy
) = initial_reg_note_copy (REG_NOTES (insn
), map
);
2012 /* Because the USAGE information potentially contains objects other
2013 than hard registers, we need to copy it. */
2014 CALL_INSN_FUNCTION_USAGE (copy
) =
2015 copy_rtx_and_substitute (CALL_INSN_FUNCTION_USAGE (insn
), map
);
2019 try_constants (cc0_insn
, map
);
2022 try_constants (copy
, map
);
2024 /* Be lazy and assume CALL_INSNs clobber all hard registers. */
2025 for (i
= 0; i
< FIRST_PSEUDO_REGISTER
; i
++)
2026 map
->const_equiv_map
[i
] = 0;
2030 /* If this is the loop start label, then we don't need to emit a
2031 copy of this label since no one will use it. */
2033 if (insn
!= start_label
)
2035 copy
= emit_label (map
->label_map
[CODE_LABEL_NUMBER (insn
)]);
2041 copy
= emit_barrier ();
2045 /* VTOP notes are valid only before the loop exit test. If placed
2046 anywhere else, loop may generate bad code. */
2048 if (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
2049 && (NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_VTOP
2050 || (last_iteration
&& unroll_type
!= UNROLL_COMPLETELY
)))
2051 copy
= emit_note (NOTE_SOURCE_FILE (insn
),
2052 NOTE_LINE_NUMBER (insn
));
2062 map
->insn_map
[INSN_UID (insn
)] = copy
;
2064 while (insn
!= copy_end
);
2066 /* Now finish coping the REG_NOTES. */
2070 insn
= NEXT_INSN (insn
);
2071 if ((GET_CODE (insn
) == INSN
|| GET_CODE (insn
) == JUMP_INSN
2072 || GET_CODE (insn
) == CALL_INSN
)
2073 && map
->insn_map
[INSN_UID (insn
)])
2074 final_reg_note_copy (REG_NOTES (map
->insn_map
[INSN_UID (insn
)]), map
);
2076 while (insn
!= copy_end
);
2078 /* There may be notes between copy_notes_from and loop_end. Emit a copy of
2079 each of these notes here, since there may be some important ones, such as
2080 NOTE_INSN_BLOCK_END notes, in this group. We don't do this on the last
2081 iteration, because the original notes won't be deleted.
2083 We can't use insert_before here, because when from preconditioning,
2084 insert_before points before the loop. We can't use copy_end, because
2085 there may be insns already inserted after it (which we don't want to
2086 copy) when not from preconditioning code. */
2088 if (! last_iteration
)
2090 for (insn
= copy_notes_from
; insn
!= loop_end
; insn
= NEXT_INSN (insn
))
2092 if (GET_CODE (insn
) == NOTE
2093 && NOTE_LINE_NUMBER (insn
) != NOTE_INSN_DELETED
)
2094 emit_note (NOTE_SOURCE_FILE (insn
), NOTE_LINE_NUMBER (insn
));
2098 if (final_label
&& LABEL_NUSES (final_label
) > 0)
2099 emit_label (final_label
);
2101 tem
= gen_sequence ();
2103 emit_insn_before (tem
, insert_before
);
2106 /* Emit an insn, using the expand_binop to ensure that a valid insn is
2107 emitted. This will correctly handle the case where the increment value
2108 won't fit in the immediate field of a PLUS insns. */
2111 emit_unrolled_add (dest_reg
, src_reg
, increment
)
2112 rtx dest_reg
, src_reg
, increment
;
2116 result
= expand_binop (GET_MODE (dest_reg
), add_optab
, src_reg
, increment
,
2117 dest_reg
, 0, OPTAB_LIB_WIDEN
);
2119 if (dest_reg
!= result
)
2120 emit_move_insn (dest_reg
, result
);
2123 /* Searches the insns between INSN and LOOP_END. Returns 1 if there
2124 is a backward branch in that range that branches to somewhere between
2125 LOOP_START and INSN. Returns 0 otherwise. */
2127 /* ??? This is quadratic algorithm. Could be rewritten to be linear.
2128 In practice, this is not a problem, because this function is seldom called,
2129 and uses a negligible amount of CPU time on average. */
2132 back_branch_in_range_p (insn
, loop_start
, loop_end
)
2134 rtx loop_start
, loop_end
;
2136 rtx p
, q
, target_insn
;
2138 /* Stop before we get to the backward branch at the end of the loop. */
2139 loop_end
= prev_nonnote_insn (loop_end
);
2140 if (GET_CODE (loop_end
) == BARRIER
)
2141 loop_end
= PREV_INSN (loop_end
);
2143 /* Check in case insn has been deleted, search forward for first non
2144 deleted insn following it. */
2145 while (INSN_DELETED_P (insn
))
2146 insn
= NEXT_INSN (insn
);
2148 /* Check for the case where insn is the last insn in the loop. */
2149 if (insn
== loop_end
)
2152 for (p
= NEXT_INSN (insn
); p
!= loop_end
; p
= NEXT_INSN (p
))
2154 if (GET_CODE (p
) == JUMP_INSN
)
2156 target_insn
= JUMP_LABEL (p
);
2158 /* Search from loop_start to insn, to see if one of them is
2159 the target_insn. We can't use INSN_LUID comparisons here,
2160 since insn may not have an LUID entry. */
2161 for (q
= loop_start
; q
!= insn
; q
= NEXT_INSN (q
))
2162 if (q
== target_insn
)
2170 /* Try to generate the simplest rtx for the expression
2171 (PLUS (MULT mult1 mult2) add1). This is used to calculate the initial
2175 fold_rtx_mult_add (mult1
, mult2
, add1
, mode
)
2176 rtx mult1
, mult2
, add1
;
2177 enum machine_mode mode
;
2182 /* The modes must all be the same. This should always be true. For now,
2183 check to make sure. */
2184 if ((GET_MODE (mult1
) != mode
&& GET_MODE (mult1
) != VOIDmode
)
2185 || (GET_MODE (mult2
) != mode
&& GET_MODE (mult2
) != VOIDmode
)
2186 || (GET_MODE (add1
) != mode
&& GET_MODE (add1
) != VOIDmode
))
2189 /* Ensure that if at least one of mult1/mult2 are constant, then mult2
2190 will be a constant. */
2191 if (GET_CODE (mult1
) == CONST_INT
)
2198 mult_res
= simplify_binary_operation (MULT
, mode
, mult1
, mult2
);
2200 mult_res
= gen_rtx (MULT
, mode
, mult1
, mult2
);
2202 /* Again, put the constant second. */
2203 if (GET_CODE (add1
) == CONST_INT
)
2210 result
= simplify_binary_operation (PLUS
, mode
, add1
, mult_res
);
2212 result
= gen_rtx (PLUS
, mode
, add1
, mult_res
);
2217 /* Searches the list of induction struct's for the biv BL, to try to calculate
2218 the total increment value for one iteration of the loop as a constant.
2220 Returns the increment value as an rtx, simplified as much as possible,
2221 if it can be calculated. Otherwise, returns 0. */
2224 biv_total_increment (bl
, loop_start
, loop_end
)
2225 struct iv_class
*bl
;
2226 rtx loop_start
, loop_end
;
2228 struct induction
*v
;
2231 /* For increment, must check every instruction that sets it. Each
2232 instruction must be executed only once each time through the loop.
2233 To verify this, we check that the the insn is always executed, and that
2234 there are no backward branches after the insn that branch to before it.
2235 Also, the insn must have a mult_val of one (to make sure it really is
2238 result
= const0_rtx
;
2239 for (v
= bl
->biv
; v
; v
= v
->next_iv
)
2241 if (v
->always_computable
&& v
->mult_val
== const1_rtx
2242 && ! back_branch_in_range_p (v
->insn
, loop_start
, loop_end
))
2243 result
= fold_rtx_mult_add (result
, const1_rtx
, v
->add_val
, v
->mode
);
2251 /* Determine the initial value of the iteration variable, and the amount
2252 that it is incremented each loop. Use the tables constructed by
2253 the strength reduction pass to calculate these values.
2255 Initial_value and/or increment are set to zero if their values could not
2259 iteration_info (iteration_var
, initial_value
, increment
, loop_start
, loop_end
)
2260 rtx iteration_var
, *initial_value
, *increment
;
2261 rtx loop_start
, loop_end
;
2263 struct iv_class
*bl
;
2264 struct induction
*v
, *b
;
2266 /* Clear the result values, in case no answer can be found. */
2270 /* The iteration variable can be either a giv or a biv. Check to see
2271 which it is, and compute the variable's initial value, and increment
2272 value if possible. */
2274 /* If this is a new register, can't handle it since we don't have any
2275 reg_iv_type entry for it. */
2276 if (REGNO (iteration_var
) >= max_reg_before_loop
)
2278 if (loop_dump_stream
)
2279 fprintf (loop_dump_stream
,
2280 "Loop unrolling: No reg_iv_type entry for iteration var.\n");
2284 /* Reject iteration variables larger than the host wide int size, since they
2285 could result in a number of iterations greater than the range of our
2286 `unsigned HOST_WIDE_INT' variable loop_n_iterations. */
2287 else if ((GET_MODE_BITSIZE (GET_MODE (iteration_var
))
2288 > HOST_BITS_PER_WIDE_INT
))
2290 if (loop_dump_stream
)
2291 fprintf (loop_dump_stream
,
2292 "Loop unrolling: Iteration var rejected because mode too large.\n");
2295 else if (GET_MODE_CLASS (GET_MODE (iteration_var
)) != MODE_INT
)
2297 if (loop_dump_stream
)
2298 fprintf (loop_dump_stream
,
2299 "Loop unrolling: Iteration var not an integer.\n");
2302 else if (reg_iv_type
[REGNO (iteration_var
)] == BASIC_INDUCT
)
2304 /* Grab initial value, only useful if it is a constant. */
2305 bl
= reg_biv_class
[REGNO (iteration_var
)];
2306 *initial_value
= bl
->initial_value
;
2308 *increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2310 else if (reg_iv_type
[REGNO (iteration_var
)] == GENERAL_INDUCT
)
2313 /* ??? The code below does not work because the incorrect number of
2314 iterations is calculated when the biv is incremented after the giv
2315 is set (which is the usual case). This can probably be accounted
2316 for by biasing the initial_value by subtracting the amount of the
2317 increment that occurs between the giv set and the giv test. However,
2318 a giv as an iterator is very rare, so it does not seem worthwhile
2320 /* ??? An example failure is: i = 6; do {;} while (i++ < 9). */
2321 if (loop_dump_stream
)
2322 fprintf (loop_dump_stream
,
2323 "Loop unrolling: Giv iterators are not handled.\n");
2326 /* Initial value is mult_val times the biv's initial value plus
2327 add_val. Only useful if it is a constant. */
2328 v
= reg_iv_info
[REGNO (iteration_var
)];
2329 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
2330 *initial_value
= fold_rtx_mult_add (v
->mult_val
, bl
->initial_value
,
2331 v
->add_val
, v
->mode
);
2333 /* Increment value is mult_val times the increment value of the biv. */
2335 *increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2337 *increment
= fold_rtx_mult_add (v
->mult_val
, *increment
, const0_rtx
,
2343 if (loop_dump_stream
)
2344 fprintf (loop_dump_stream
,
2345 "Loop unrolling: Not basic or general induction var.\n");
2350 /* Calculate the approximate final value of the iteration variable
2351 which has an loop exit test with code COMPARISON_CODE and comparison value
2352 of COMPARISON_VALUE. Also returns an indication of whether the comparison
2353 was signed or unsigned, and the direction of the comparison. This info is
2354 needed to calculate the number of loop iterations. */
2357 approx_final_value (comparison_code
, comparison_value
, unsigned_p
, compare_dir
)
2358 enum rtx_code comparison_code
;
2359 rtx comparison_value
;
2363 /* Calculate the final value of the induction variable.
2364 The exact final value depends on the branch operator, and increment sign.
2365 This is only an approximate value. It will be wrong if the iteration
2366 variable is not incremented by one each time through the loop, and
2367 approx final value - start value % increment != 0. */
2370 switch (comparison_code
)
2376 return plus_constant (comparison_value
, 1);
2381 return plus_constant (comparison_value
, -1);
2383 /* Can not calculate a final value for this case. */
2390 return comparison_value
;
2396 return comparison_value
;
2399 return comparison_value
;
2405 /* For each biv and giv, determine whether it can be safely split into
2406 a different variable for each unrolled copy of the loop body. If it
2407 is safe to split, then indicate that by saving some useful info
2408 in the splittable_regs array.
2410 If the loop is being completely unrolled, then splittable_regs will hold
2411 the current value of the induction variable while the loop is unrolled.
2412 It must be set to the initial value of the induction variable here.
2413 Otherwise, splittable_regs will hold the difference between the current
2414 value of the induction variable and the value the induction variable had
2415 at the top of the loop. It must be set to the value 0 here.
2417 Returns the total number of instructions that set registers that are
2420 /* ?? If the loop is only unrolled twice, then most of the restrictions to
2421 constant values are unnecessary, since we can easily calculate increment
2422 values in this case even if nothing is constant. The increment value
2423 should not involve a multiply however. */
2425 /* ?? Even if the biv/giv increment values aren't constant, it may still
2426 be beneficial to split the variable if the loop is only unrolled a few
2427 times, since multiplies by small integers (1,2,3,4) are very cheap. */
2430 find_splittable_regs (unroll_type
, loop_start
, loop_end
, end_insert_before
,
2432 enum unroll_types unroll_type
;
2433 rtx loop_start
, loop_end
;
2434 rtx end_insert_before
;
2437 struct iv_class
*bl
;
2438 struct induction
*v
;
2440 rtx biv_final_value
;
2444 for (bl
= loop_iv_list
; bl
; bl
= bl
->next
)
2446 /* Biv_total_increment must return a constant value,
2447 otherwise we can not calculate the split values. */
2449 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
2450 if (! increment
|| GET_CODE (increment
) != CONST_INT
)
2453 /* The loop must be unrolled completely, or else have a known number
2454 of iterations and only one exit, or else the biv must be dead
2455 outside the loop, or else the final value must be known. Otherwise,
2456 it is unsafe to split the biv since it may not have the proper
2457 value on loop exit. */
2459 /* loop_number_exit_count is non-zero if the loop has an exit other than
2460 a fall through at the end. */
2463 biv_final_value
= 0;
2464 if (unroll_type
!= UNROLL_COMPLETELY
2465 && (loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
2466 || unroll_type
== UNROLL_NAIVE
)
2467 && (uid_luid
[regno_last_uid
[bl
->regno
]] >= INSN_LUID (loop_end
)
2469 || INSN_UID (bl
->init_insn
) >= max_uid_for_loop
2470 || (uid_luid
[regno_first_uid
[bl
->regno
]]
2471 < INSN_LUID (bl
->init_insn
))
2472 || reg_mentioned_p (bl
->biv
->dest_reg
, SET_SRC (bl
->init_set
)))
2473 && ! (biv_final_value
= final_biv_value (bl
, loop_start
, loop_end
)))
2476 /* If any of the insns setting the BIV don't do so with a simple
2477 PLUS, we don't know how to split it. */
2478 for (v
= bl
->biv
; biv_splittable
&& v
; v
= v
->next_iv
)
2479 if ((tem
= single_set (v
->insn
)) == 0
2480 || GET_CODE (SET_DEST (tem
)) != REG
2481 || REGNO (SET_DEST (tem
)) != bl
->regno
2482 || GET_CODE (SET_SRC (tem
)) != PLUS
)
2485 /* If final value is non-zero, then must emit an instruction which sets
2486 the value of the biv to the proper value. This is done after
2487 handling all of the givs, since some of them may need to use the
2488 biv's value in their initialization code. */
2490 /* This biv is splittable. If completely unrolling the loop, save
2491 the biv's initial value. Otherwise, save the constant zero. */
2493 if (biv_splittable
== 1)
2495 if (unroll_type
== UNROLL_COMPLETELY
)
2497 /* If the initial value of the biv is itself (i.e. it is too
2498 complicated for strength_reduce to compute), or is a hard
2499 register, or it isn't invariant, then we must create a new
2500 pseudo reg to hold the initial value of the biv. */
2502 if (GET_CODE (bl
->initial_value
) == REG
2503 && (REGNO (bl
->initial_value
) == bl
->regno
2504 || REGNO (bl
->initial_value
) < FIRST_PSEUDO_REGISTER
2505 || ! invariant_p (bl
->initial_value
)))
2507 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2509 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2512 if (loop_dump_stream
)
2513 fprintf (loop_dump_stream
, "Biv %d initial value remapped to %d.\n",
2514 bl
->regno
, REGNO (tem
));
2516 splittable_regs
[bl
->regno
] = tem
;
2519 splittable_regs
[bl
->regno
] = bl
->initial_value
;
2522 splittable_regs
[bl
->regno
] = const0_rtx
;
2524 /* Save the number of instructions that modify the biv, so that
2525 we can treat the last one specially. */
2527 splittable_regs_updates
[bl
->regno
] = bl
->biv_count
;
2528 result
+= bl
->biv_count
;
2530 if (loop_dump_stream
)
2531 fprintf (loop_dump_stream
,
2532 "Biv %d safe to split.\n", bl
->regno
);
2535 /* Check every giv that depends on this biv to see whether it is
2536 splittable also. Even if the biv isn't splittable, givs which
2537 depend on it may be splittable if the biv is live outside the
2538 loop, and the givs aren't. */
2540 result
+= find_splittable_givs (bl
, unroll_type
, loop_start
, loop_end
,
2541 increment
, unroll_number
);
2543 /* If final value is non-zero, then must emit an instruction which sets
2544 the value of the biv to the proper value. This is done after
2545 handling all of the givs, since some of them may need to use the
2546 biv's value in their initialization code. */
2547 if (biv_final_value
)
2549 /* If the loop has multiple exits, emit the insns before the
2550 loop to ensure that it will always be executed no matter
2551 how the loop exits. Otherwise emit the insn after the loop,
2552 since this is slightly more efficient. */
2553 if (! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]])
2554 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2559 /* Create a new register to hold the value of the biv, and then
2560 set the biv to its final value before the loop start. The biv
2561 is set to its final value before loop start to ensure that
2562 this insn will always be executed, no matter how the loop
2564 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2565 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2567 emit_insn_before (gen_move_insn (bl
->biv
->src_reg
,
2571 if (loop_dump_stream
)
2572 fprintf (loop_dump_stream
, "Biv %d mapped to %d for split.\n",
2573 REGNO (bl
->biv
->src_reg
), REGNO (tem
));
2575 /* Set up the mapping from the original biv register to the new
2577 bl
->biv
->src_reg
= tem
;
2584 /* Return 1 if the first and last unrolled copy of the address giv V is valid
2585 for the instruction that is using it. Do not make any changes to that
2589 verify_addresses (v
, giv_inc
, unroll_number
)
2590 struct induction
*v
;
2595 rtx orig_addr
= *v
->location
;
2596 rtx last_addr
= plus_constant (v
->dest_reg
,
2597 INTVAL (giv_inc
) * (unroll_number
- 1));
2599 /* First check to see if either address would fail. */
2600 if (! validate_change (v
->insn
, v
->location
, v
->dest_reg
, 0)
2601 || ! validate_change (v
->insn
, v
->location
, last_addr
, 0))
2604 /* Now put things back the way they were before. This will always
2606 validate_change (v
->insn
, v
->location
, orig_addr
, 0);
2611 /* For every giv based on the biv BL, check to determine whether it is
2612 splittable. This is a subroutine to find_splittable_regs ().
2614 Return the number of instructions that set splittable registers. */
2617 find_splittable_givs (bl
, unroll_type
, loop_start
, loop_end
, increment
,
2619 struct iv_class
*bl
;
2620 enum unroll_types unroll_type
;
2621 rtx loop_start
, loop_end
;
2625 struct induction
*v
, *v2
;
2630 /* Scan the list of givs, and set the same_insn field when there are
2631 multiple identical givs in the same insn. */
2632 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2633 for (v2
= v
->next_iv
; v2
; v2
= v2
->next_iv
)
2634 if (v
->insn
== v2
->insn
&& rtx_equal_p (v
->new_reg
, v2
->new_reg
)
2638 for (v
= bl
->giv
; v
; v
= v
->next_iv
)
2642 /* Only split the giv if it has already been reduced, or if the loop is
2643 being completely unrolled. */
2644 if (unroll_type
!= UNROLL_COMPLETELY
&& v
->ignore
)
2647 /* The giv can be split if the insn that sets the giv is executed once
2648 and only once on every iteration of the loop. */
2649 /* An address giv can always be split. v->insn is just a use not a set,
2650 and hence it does not matter whether it is always executed. All that
2651 matters is that all the biv increments are always executed, and we
2652 won't reach here if they aren't. */
2653 if (v
->giv_type
!= DEST_ADDR
2654 && (! v
->always_computable
2655 || back_branch_in_range_p (v
->insn
, loop_start
, loop_end
)))
2658 /* The giv increment value must be a constant. */
2659 giv_inc
= fold_rtx_mult_add (v
->mult_val
, increment
, const0_rtx
,
2661 if (! giv_inc
|| GET_CODE (giv_inc
) != CONST_INT
)
2664 /* The loop must be unrolled completely, or else have a known number of
2665 iterations and only one exit, or else the giv must be dead outside
2666 the loop, or else the final value of the giv must be known.
2667 Otherwise, it is not safe to split the giv since it may not have the
2668 proper value on loop exit. */
2670 /* The used outside loop test will fail for DEST_ADDR givs. They are
2671 never used outside the loop anyways, so it is always safe to split a
2675 if (unroll_type
!= UNROLL_COMPLETELY
2676 && (loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
2677 || unroll_type
== UNROLL_NAIVE
)
2678 && v
->giv_type
!= DEST_ADDR
2679 && ((regno_first_uid
[REGNO (v
->dest_reg
)] != INSN_UID (v
->insn
)
2680 /* Check for the case where the pseudo is set by a shift/add
2681 sequence, in which case the first insn setting the pseudo
2682 is the first insn of the shift/add sequence. */
2683 && (! (tem
= find_reg_note (v
->insn
, REG_RETVAL
, NULL_RTX
))
2684 || (regno_first_uid
[REGNO (v
->dest_reg
)]
2685 != INSN_UID (XEXP (tem
, 0)))))
2686 /* Line above always fails if INSN was moved by loop opt. */
2687 || (uid_luid
[regno_last_uid
[REGNO (v
->dest_reg
)]]
2688 >= INSN_LUID (loop_end
)))
2689 && ! (final_value
= v
->final_value
))
2693 /* Currently, non-reduced/final-value givs are never split. */
2694 /* Should emit insns after the loop if possible, as the biv final value
2697 /* If the final value is non-zero, and the giv has not been reduced,
2698 then must emit an instruction to set the final value. */
2699 if (final_value
&& !v
->new_reg
)
2701 /* Create a new register to hold the value of the giv, and then set
2702 the giv to its final value before the loop start. The giv is set
2703 to its final value before loop start to ensure that this insn
2704 will always be executed, no matter how we exit. */
2705 tem
= gen_reg_rtx (v
->mode
);
2706 emit_insn_before (gen_move_insn (tem
, v
->dest_reg
), loop_start
);
2707 emit_insn_before (gen_move_insn (v
->dest_reg
, final_value
),
2710 if (loop_dump_stream
)
2711 fprintf (loop_dump_stream
, "Giv %d mapped to %d for split.\n",
2712 REGNO (v
->dest_reg
), REGNO (tem
));
2718 /* This giv is splittable. If completely unrolling the loop, save the
2719 giv's initial value. Otherwise, save the constant zero for it. */
2721 if (unroll_type
== UNROLL_COMPLETELY
)
2723 /* It is not safe to use bl->initial_value here, because it may not
2724 be invariant. It is safe to use the initial value stored in
2725 the splittable_regs array if it is set. In rare cases, it won't
2726 be set, so then we do exactly the same thing as
2727 find_splittable_regs does to get a safe value. */
2728 rtx biv_initial_value
;
2730 if (splittable_regs
[bl
->regno
])
2731 biv_initial_value
= splittable_regs
[bl
->regno
];
2732 else if (GET_CODE (bl
->initial_value
) != REG
2733 || (REGNO (bl
->initial_value
) != bl
->regno
2734 && REGNO (bl
->initial_value
) >= FIRST_PSEUDO_REGISTER
))
2735 biv_initial_value
= bl
->initial_value
;
2738 rtx tem
= gen_reg_rtx (bl
->biv
->mode
);
2740 emit_insn_before (gen_move_insn (tem
, bl
->biv
->src_reg
),
2742 biv_initial_value
= tem
;
2744 value
= fold_rtx_mult_add (v
->mult_val
, biv_initial_value
,
2745 v
->add_val
, v
->mode
);
2752 /* If a giv was combined with another giv, then we can only split
2753 this giv if the giv it was combined with was reduced. This
2754 is because the value of v->new_reg is meaningless in this
2756 if (v
->same
&& ! v
->same
->new_reg
)
2758 if (loop_dump_stream
)
2759 fprintf (loop_dump_stream
,
2760 "giv combined with unreduced giv not split.\n");
2763 /* If the giv is an address destination, it could be something other
2764 than a simple register, these have to be treated differently. */
2765 else if (v
->giv_type
== DEST_REG
)
2767 /* If value is not a constant, register, or register plus
2768 constant, then compute its value into a register before
2769 loop start. This prevents invalid rtx sharing, and should
2770 generate better code. We can use bl->initial_value here
2771 instead of splittable_regs[bl->regno] because this code
2772 is going before the loop start. */
2773 if (unroll_type
== UNROLL_COMPLETELY
2774 && GET_CODE (value
) != CONST_INT
2775 && GET_CODE (value
) != REG
2776 && (GET_CODE (value
) != PLUS
2777 || GET_CODE (XEXP (value
, 0)) != REG
2778 || GET_CODE (XEXP (value
, 1)) != CONST_INT
))
2780 rtx tem
= gen_reg_rtx (v
->mode
);
2781 emit_iv_add_mult (bl
->initial_value
, v
->mult_val
,
2782 v
->add_val
, tem
, loop_start
);
2786 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2790 /* Splitting address givs is useful since it will often allow us
2791 to eliminate some increment insns for the base giv as
2794 /* If the addr giv is combined with a dest_reg giv, then all
2795 references to that dest reg will be remapped, which is NOT
2796 what we want for split addr regs. We always create a new
2797 register for the split addr giv, just to be safe. */
2799 /* ??? If there are multiple address givs which have been
2800 combined with the same dest_reg giv, then we may only need
2801 one new register for them. Pulling out constants below will
2802 catch some of the common cases of this. Currently, I leave
2803 the work of simplifying multiple address givs to the
2804 following cse pass. */
2806 /* As a special case, if we have multiple identical address givs
2807 within a single instruction, then we do use a single pseudo
2808 reg for both. This is necessary in case one is a match_dup
2811 v
->const_adjust
= 0;
2815 v
->dest_reg
= v
->same_insn
->dest_reg
;
2816 if (loop_dump_stream
)
2817 fprintf (loop_dump_stream
,
2818 "Sharing address givs in insn %d\n",
2819 INSN_UID (v
->insn
));
2821 else if (unroll_type
!= UNROLL_COMPLETELY
)
2823 /* If not completely unrolling the loop, then create a new
2824 register to hold the split value of the DEST_ADDR giv.
2825 Emit insn to initialize its value before loop start. */
2826 tem
= gen_reg_rtx (v
->mode
);
2828 /* If the address giv has a constant in its new_reg value,
2829 then this constant can be pulled out and put in value,
2830 instead of being part of the initialization code. */
2832 if (GET_CODE (v
->new_reg
) == PLUS
2833 && GET_CODE (XEXP (v
->new_reg
, 1)) == CONST_INT
)
2836 = plus_constant (tem
, INTVAL (XEXP (v
->new_reg
,1)));
2838 /* Only succeed if this will give valid addresses.
2839 Try to validate both the first and the last
2840 address resulting from loop unrolling, if
2841 one fails, then can't do const elim here. */
2842 if (verify_addresses (v
, giv_inc
, unroll_number
))
2844 /* Save the negative of the eliminated const, so
2845 that we can calculate the dest_reg's increment
2847 v
->const_adjust
= - INTVAL (XEXP (v
->new_reg
, 1));
2849 v
->new_reg
= XEXP (v
->new_reg
, 0);
2850 if (loop_dump_stream
)
2851 fprintf (loop_dump_stream
,
2852 "Eliminating constant from giv %d\n",
2861 /* If the address hasn't been checked for validity yet, do so
2862 now, and fail completely if either the first or the last
2863 unrolled copy of the address is not a valid address
2864 for the instruction that uses it. */
2865 if (v
->dest_reg
== tem
2866 && ! verify_addresses (v
, giv_inc
, unroll_number
))
2868 if (loop_dump_stream
)
2869 fprintf (loop_dump_stream
,
2870 "Invalid address for giv at insn %d\n",
2871 INSN_UID (v
->insn
));
2875 /* To initialize the new register, just move the value of
2876 new_reg into it. This is not guaranteed to give a valid
2877 instruction on machines with complex addressing modes.
2878 If we can't recognize it, then delete it and emit insns
2879 to calculate the value from scratch. */
2880 emit_insn_before (gen_rtx (SET
, VOIDmode
, tem
,
2881 copy_rtx (v
->new_reg
)),
2883 if (recog_memoized (PREV_INSN (loop_start
)) < 0)
2887 /* We can't use bl->initial_value to compute the initial
2888 value, because the loop may have been preconditioned.
2889 We must calculate it from NEW_REG. Try using
2890 force_operand instead of emit_iv_add_mult. */
2891 delete_insn (PREV_INSN (loop_start
));
2894 ret
= force_operand (v
->new_reg
, tem
);
2896 emit_move_insn (tem
, ret
);
2897 sequence
= gen_sequence ();
2899 emit_insn_before (sequence
, loop_start
);
2901 if (loop_dump_stream
)
2902 fprintf (loop_dump_stream
,
2903 "Invalid init insn, rewritten.\n");
2908 v
->dest_reg
= value
;
2910 /* Check the resulting address for validity, and fail
2911 if the resulting address would be invalid. */
2912 if (! verify_addresses (v
, giv_inc
, unroll_number
))
2914 if (loop_dump_stream
)
2915 fprintf (loop_dump_stream
,
2916 "Invalid address for giv at insn %d\n",
2917 INSN_UID (v
->insn
));
2922 /* Store the value of dest_reg into the insn. This sharing
2923 will not be a problem as this insn will always be copied
2926 *v
->location
= v
->dest_reg
;
2928 /* If this address giv is combined with a dest reg giv, then
2929 save the base giv's induction pointer so that we will be
2930 able to handle this address giv properly. The base giv
2931 itself does not have to be splittable. */
2933 if (v
->same
&& v
->same
->giv_type
== DEST_REG
)
2934 addr_combined_regs
[REGNO (v
->same
->new_reg
)] = v
->same
;
2936 if (GET_CODE (v
->new_reg
) == REG
)
2938 /* This giv maybe hasn't been combined with any others.
2939 Make sure that it's giv is marked as splittable here. */
2941 splittable_regs
[REGNO (v
->new_reg
)] = value
;
2943 /* Make it appear to depend upon itself, so that the
2944 giv will be properly split in the main loop above. */
2948 addr_combined_regs
[REGNO (v
->new_reg
)] = v
;
2952 if (loop_dump_stream
)
2953 fprintf (loop_dump_stream
, "DEST_ADDR giv being split.\n");
2959 /* Currently, unreduced giv's can't be split. This is not too much
2960 of a problem since unreduced giv's are not live across loop
2961 iterations anyways. When unrolling a loop completely though,
2962 it makes sense to reduce&split givs when possible, as this will
2963 result in simpler instructions, and will not require that a reg
2964 be live across loop iterations. */
2966 splittable_regs
[REGNO (v
->dest_reg
)] = value
;
2967 fprintf (stderr
, "Giv %d at insn %d not reduced\n",
2968 REGNO (v
->dest_reg
), INSN_UID (v
->insn
));
2974 /* Givs are only updated once by definition. Mark it so if this is
2975 a splittable register. Don't need to do anything for address givs
2976 where this may not be a register. */
2978 if (GET_CODE (v
->new_reg
) == REG
)
2979 splittable_regs_updates
[REGNO (v
->new_reg
)] = 1;
2983 if (loop_dump_stream
)
2987 if (GET_CODE (v
->dest_reg
) == CONST_INT
)
2989 else if (GET_CODE (v
->dest_reg
) != REG
)
2990 regnum
= REGNO (XEXP (v
->dest_reg
, 0));
2992 regnum
= REGNO (v
->dest_reg
);
2993 fprintf (loop_dump_stream
, "Giv %d at insn %d safe to split.\n",
2994 regnum
, INSN_UID (v
->insn
));
3001 /* Try to prove that the register is dead after the loop exits. Trace every
3002 loop exit looking for an insn that will always be executed, which sets
3003 the register to some value, and appears before the first use of the register
3004 is found. If successful, then return 1, otherwise return 0. */
3006 /* ?? Could be made more intelligent in the handling of jumps, so that
3007 it can search past if statements and other similar structures. */
3010 reg_dead_after_loop (reg
, loop_start
, loop_end
)
3011 rtx reg
, loop_start
, loop_end
;
3016 int label_count
= 0;
3017 int this_loop_num
= uid_loop_num
[INSN_UID (loop_start
)];
3019 /* In addition to checking all exits of this loop, we must also check
3020 all exits of inner nested loops that would exit this loop. We don't
3021 have any way to identify those, so we just give up if there are any
3022 such inner loop exits. */
3024 for (label
= loop_number_exit_labels
[this_loop_num
]; label
;
3025 label
= LABEL_NEXTREF (label
))
3028 if (label_count
!= loop_number_exit_count
[this_loop_num
])
3031 /* HACK: Must also search the loop fall through exit, create a label_ref
3032 here which points to the loop_end, and append the loop_number_exit_labels
3034 label
= gen_rtx (LABEL_REF
, VOIDmode
, loop_end
);
3035 LABEL_NEXTREF (label
) = loop_number_exit_labels
[this_loop_num
];
3037 for ( ; label
; label
= LABEL_NEXTREF (label
))
3039 /* Succeed if find an insn which sets the biv or if reach end of
3040 function. Fail if find an insn that uses the biv, or if come to
3041 a conditional jump. */
3043 insn
= NEXT_INSN (XEXP (label
, 0));
3046 code
= GET_CODE (insn
);
3047 if (GET_RTX_CLASS (code
) == 'i')
3051 if (reg_referenced_p (reg
, PATTERN (insn
)))
3054 set
= single_set (insn
);
3055 if (set
&& rtx_equal_p (SET_DEST (set
), reg
))
3059 if (code
== JUMP_INSN
)
3061 if (GET_CODE (PATTERN (insn
)) == RETURN
)
3063 else if (! simplejump_p (insn
)
3064 /* Prevent infinite loop following infinite loops. */
3065 || jump_count
++ > 20)
3068 insn
= JUMP_LABEL (insn
);
3071 insn
= NEXT_INSN (insn
);
3075 /* Success, the register is dead on all loop exits. */
3079 /* Try to calculate the final value of the biv, the value it will have at
3080 the end of the loop. If we can do it, return that value. */
3083 final_biv_value (bl
, loop_start
, loop_end
)
3084 struct iv_class
*bl
;
3085 rtx loop_start
, loop_end
;
3089 /* ??? This only works for MODE_INT biv's. Reject all others for now. */
3091 if (GET_MODE_CLASS (bl
->biv
->mode
) != MODE_INT
)
3094 /* The final value for reversed bivs must be calculated differently than
3095 for ordinary bivs. In this case, there is already an insn after the
3096 loop which sets this biv's final value (if necessary), and there are
3097 no other loop exits, so we can return any value. */
3100 if (loop_dump_stream
)
3101 fprintf (loop_dump_stream
,
3102 "Final biv value for %d, reversed biv.\n", bl
->regno
);
3107 /* Try to calculate the final value as initial value + (number of iterations
3108 * increment). For this to work, increment must be invariant, the only
3109 exit from the loop must be the fall through at the bottom (otherwise
3110 it may not have its final value when the loop exits), and the initial
3111 value of the biv must be invariant. */
3113 if (loop_n_iterations
!= 0
3114 && ! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]]
3115 && invariant_p (bl
->initial_value
))
3117 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
3119 if (increment
&& invariant_p (increment
))
3121 /* Can calculate the loop exit value, emit insns after loop
3122 end to calculate this value into a temporary register in
3123 case it is needed later. */
3125 tem
= gen_reg_rtx (bl
->biv
->mode
);
3126 /* Make sure loop_end is not the last insn. */
3127 if (NEXT_INSN (loop_end
) == 0)
3128 emit_note_after (NOTE_INSN_DELETED
, loop_end
);
3129 emit_iv_add_mult (increment
, GEN_INT (loop_n_iterations
),
3130 bl
->initial_value
, tem
, NEXT_INSN (loop_end
));
3132 if (loop_dump_stream
)
3133 fprintf (loop_dump_stream
,
3134 "Final biv value for %d, calculated.\n", bl
->regno
);
3140 /* Check to see if the biv is dead at all loop exits. */
3141 if (reg_dead_after_loop (bl
->biv
->src_reg
, loop_start
, loop_end
))
3143 if (loop_dump_stream
)
3144 fprintf (loop_dump_stream
,
3145 "Final biv value for %d, biv dead after loop exit.\n",
3154 /* Try to calculate the final value of the giv, the value it will have at
3155 the end of the loop. If we can do it, return that value. */
3158 final_giv_value (v
, loop_start
, loop_end
)
3159 struct induction
*v
;
3160 rtx loop_start
, loop_end
;
3162 struct iv_class
*bl
;
3165 rtx insert_before
, seq
;
3167 bl
= reg_biv_class
[REGNO (v
->src_reg
)];
3169 /* The final value for givs which depend on reversed bivs must be calculated
3170 differently than for ordinary givs. In this case, there is already an
3171 insn after the loop which sets this giv's final value (if necessary),
3172 and there are no other loop exits, so we can return any value. */
3175 if (loop_dump_stream
)
3176 fprintf (loop_dump_stream
,
3177 "Final giv value for %d, depends on reversed biv\n",
3178 REGNO (v
->dest_reg
));
3182 /* Try to calculate the final value as a function of the biv it depends
3183 upon. The only exit from the loop must be the fall through at the bottom
3184 (otherwise it may not have its final value when the loop exits). */
3186 /* ??? Can calculate the final giv value by subtracting off the
3187 extra biv increments times the giv's mult_val. The loop must have
3188 only one exit for this to work, but the loop iterations does not need
3191 if (loop_n_iterations
!= 0
3192 && ! loop_number_exit_count
[uid_loop_num
[INSN_UID (loop_start
)]])
3194 /* ?? It is tempting to use the biv's value here since these insns will
3195 be put after the loop, and hence the biv will have its final value
3196 then. However, this fails if the biv is subsequently eliminated.
3197 Perhaps determine whether biv's are eliminable before trying to
3198 determine whether giv's are replaceable so that we can use the
3199 biv value here if it is not eliminable. */
3201 increment
= biv_total_increment (bl
, loop_start
, loop_end
);
3203 if (increment
&& invariant_p (increment
))
3205 /* Can calculate the loop exit value of its biv as
3206 (loop_n_iterations * increment) + initial_value */
3208 /* The loop exit value of the giv is then
3209 (final_biv_value - extra increments) * mult_val + add_val.
3210 The extra increments are any increments to the biv which
3211 occur in the loop after the giv's value is calculated.
3212 We must search from the insn that sets the giv to the end
3213 of the loop to calculate this value. */
3215 insert_before
= NEXT_INSN (loop_end
);
3217 /* Put the final biv value in tem. */
3218 tem
= gen_reg_rtx (bl
->biv
->mode
);
3219 emit_iv_add_mult (increment
, GEN_INT (loop_n_iterations
),
3220 bl
->initial_value
, tem
, insert_before
);
3222 /* Subtract off extra increments as we find them. */
3223 for (insn
= NEXT_INSN (v
->insn
); insn
!= loop_end
;
3224 insn
= NEXT_INSN (insn
))
3226 struct induction
*biv
;
3228 for (biv
= bl
->biv
; biv
; biv
= biv
->next_iv
)
3229 if (biv
->insn
== insn
)
3232 tem
= expand_binop (GET_MODE (tem
), sub_optab
, tem
,
3233 biv
->add_val
, NULL_RTX
, 0,
3235 seq
= gen_sequence ();
3237 emit_insn_before (seq
, insert_before
);
3241 /* Now calculate the giv's final value. */
3242 emit_iv_add_mult (tem
, v
->mult_val
, v
->add_val
, tem
,
3245 if (loop_dump_stream
)
3246 fprintf (loop_dump_stream
,
3247 "Final giv value for %d, calc from biv's value.\n",
3248 REGNO (v
->dest_reg
));
3254 /* Replaceable giv's should never reach here. */
3258 /* Check to see if the biv is dead at all loop exits. */
3259 if (reg_dead_after_loop (v
->dest_reg
, loop_start
, loop_end
))
3261 if (loop_dump_stream
)
3262 fprintf (loop_dump_stream
,
3263 "Final giv value for %d, giv dead after loop exit.\n",
3264 REGNO (v
->dest_reg
));
3273 /* Calculate the number of loop iterations. Returns the exact number of loop
3274 iterations if it can be calculated, otherwise returns zero. */
3276 unsigned HOST_WIDE_INT
3277 loop_iterations (loop_start
, loop_end
)
3278 rtx loop_start
, loop_end
;
3280 rtx comparison
, comparison_value
;
3281 rtx iteration_var
, initial_value
, increment
, final_value
;
3282 enum rtx_code comparison_code
;
3285 int unsigned_compare
, compare_dir
, final_larger
;
3286 unsigned long tempu
;
3289 /* First find the iteration variable. If the last insn is a conditional
3290 branch, and the insn before tests a register value, make that the
3291 iteration variable. */
3293 loop_initial_value
= 0;
3295 loop_final_value
= 0;
3296 loop_iteration_var
= 0;
3298 /* We used to use pren_nonnote_insn here, but that fails because it might
3299 accidentally get the branch for a contained loop if the branch for this
3300 loop was deleted. We can only trust branches immediately before the
3302 last_loop_insn
= PREV_INSN (loop_end
);
3304 comparison
= get_condition_for_loop (last_loop_insn
);
3305 if (comparison
== 0)
3307 if (loop_dump_stream
)
3308 fprintf (loop_dump_stream
,
3309 "Loop unrolling: No final conditional branch found.\n");
3313 /* ??? Get_condition may switch position of induction variable and
3314 invariant register when it canonicalizes the comparison. */
3316 comparison_code
= GET_CODE (comparison
);
3317 iteration_var
= XEXP (comparison
, 0);
3318 comparison_value
= XEXP (comparison
, 1);
3320 if (GET_CODE (iteration_var
) != REG
)
3322 if (loop_dump_stream
)
3323 fprintf (loop_dump_stream
,
3324 "Loop unrolling: Comparison not against register.\n");
3328 /* Loop iterations is always called before any new registers are created
3329 now, so this should never occur. */
3331 if (REGNO (iteration_var
) >= max_reg_before_loop
)
3334 iteration_info (iteration_var
, &initial_value
, &increment
,
3335 loop_start
, loop_end
);
3336 if (initial_value
== 0)
3337 /* iteration_info already printed a message. */
3340 /* If the comparison value is an invariant register, then try to find
3341 its value from the insns before the start of the loop. */
3343 if (GET_CODE (comparison_value
) == REG
&& invariant_p (comparison_value
))
3347 for (insn
= PREV_INSN (loop_start
); insn
; insn
= PREV_INSN (insn
))
3349 if (GET_CODE (insn
) == CODE_LABEL
)
3352 else if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i'
3353 && reg_set_p (comparison_value
, insn
))
3355 /* We found the last insn before the loop that sets the register.
3356 If it sets the entire register, and has a REG_EQUAL note,
3357 then use the value of the REG_EQUAL note. */
3358 if ((set
= single_set (insn
))
3359 && (SET_DEST (set
) == comparison_value
))
3361 rtx note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
3363 /* Only use the REG_EQUAL note if it is a constant.
3364 Other things, divide in particular, will cause
3365 problems later if we use them. */
3366 if (note
&& GET_CODE (XEXP (note
, 0)) != EXPR_LIST
3367 && CONSTANT_P (XEXP (note
, 0)))
3368 comparison_value
= XEXP (note
, 0);
3375 final_value
= approx_final_value (comparison_code
, comparison_value
,
3376 &unsigned_compare
, &compare_dir
);
3378 /* Save the calculated values describing this loop's bounds, in case
3379 precondition_loop_p will need them later. These values can not be
3380 recalculated inside precondition_loop_p because strength reduction
3381 optimizations may obscure the loop's structure. */
3383 loop_iteration_var
= iteration_var
;
3384 loop_initial_value
= initial_value
;
3385 loop_increment
= increment
;
3386 loop_final_value
= final_value
;
3387 loop_comparison_code
= comparison_code
;
3391 if (loop_dump_stream
)
3392 fprintf (loop_dump_stream
,
3393 "Loop unrolling: Increment value can't be calculated.\n");
3396 else if (GET_CODE (increment
) != CONST_INT
)
3398 if (loop_dump_stream
)
3399 fprintf (loop_dump_stream
,
3400 "Loop unrolling: Increment value not constant.\n");
3403 else if (GET_CODE (initial_value
) != CONST_INT
)
3405 if (loop_dump_stream
)
3406 fprintf (loop_dump_stream
,
3407 "Loop unrolling: Initial value not constant.\n");
3410 else if (final_value
== 0)
3412 if (loop_dump_stream
)
3413 fprintf (loop_dump_stream
,
3414 "Loop unrolling: EQ comparison loop.\n");
3417 else if (GET_CODE (final_value
) != CONST_INT
)
3419 if (loop_dump_stream
)
3420 fprintf (loop_dump_stream
,
3421 "Loop unrolling: Final value not constant.\n");
3425 /* ?? Final value and initial value do not have to be constants.
3426 Only their difference has to be constant. When the iteration variable
3427 is an array address, the final value and initial value might both
3428 be addresses with the same base but different constant offsets.
3429 Final value must be invariant for this to work.
3431 To do this, need some way to find the values of registers which are
3434 /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1. */
3435 if (unsigned_compare
)
3437 = ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3438 > (unsigned HOST_WIDE_INT
) INTVAL (initial_value
))
3439 - ((unsigned HOST_WIDE_INT
) INTVAL (final_value
)
3440 < (unsigned HOST_WIDE_INT
) INTVAL (initial_value
));
3442 final_larger
= (INTVAL (final_value
) > INTVAL (initial_value
))
3443 - (INTVAL (final_value
) < INTVAL (initial_value
));
3445 if (INTVAL (increment
) > 0)
3447 else if (INTVAL (increment
) == 0)
3452 /* There are 27 different cases: compare_dir = -1, 0, 1;
3453 final_larger = -1, 0, 1; increment_dir = -1, 0, 1.
3454 There are 4 normal cases, 4 reverse cases (where the iteration variable
3455 will overflow before the loop exits), 4 infinite loop cases, and 15
3456 immediate exit (0 or 1 iteration depending on loop type) cases.
3457 Only try to optimize the normal cases. */
3459 /* (compare_dir/final_larger/increment_dir)
3460 Normal cases: (0/-1/-1), (0/1/1), (-1/-1/-1), (1/1/1)
3461 Reverse cases: (0/-1/1), (0/1/-1), (-1/-1/1), (1/1/-1)
3462 Infinite loops: (0/-1/0), (0/1/0), (-1/-1/0), (1/1/0)
3463 Immediate exit: (0/0/X), (-1/0/X), (-1/1/X), (1/0/X), (1/-1/X) */
3465 /* ?? If the meaning of reverse loops (where the iteration variable
3466 will overflow before the loop exits) is undefined, then could
3467 eliminate all of these special checks, and just always assume
3468 the loops are normal/immediate/infinite. Note that this means
3469 the sign of increment_dir does not have to be known. Also,
3470 since it does not really hurt if immediate exit loops or infinite loops
3471 are optimized, then that case could be ignored also, and hence all
3472 loops can be optimized.
3474 According to ANSI Spec, the reverse loop case result is undefined,
3475 because the action on overflow is undefined.
3477 See also the special test for NE loops below. */
3479 if (final_larger
== increment_dir
&& final_larger
!= 0
3480 && (final_larger
== compare_dir
|| compare_dir
== 0))
3485 if (loop_dump_stream
)
3486 fprintf (loop_dump_stream
,
3487 "Loop unrolling: Not normal loop.\n");
3491 /* Calculate the number of iterations, final_value is only an approximation,
3492 so correct for that. Note that tempu and loop_n_iterations are
3493 unsigned, because they can be as large as 2^n - 1. */
3495 i
= INTVAL (increment
);
3497 tempu
= INTVAL (final_value
) - INTVAL (initial_value
);
3500 tempu
= INTVAL (initial_value
) - INTVAL (final_value
);
3506 /* For NE tests, make sure that the iteration variable won't miss the
3507 final value. If tempu mod i is not zero, then the iteration variable
3508 will overflow before the loop exits, and we can not calculate the
3509 number of iterations. */
3510 if (compare_dir
== 0 && (tempu
% i
) != 0)
3513 return tempu
/ i
+ ((tempu
% i
) != 0);
3516 /* Replace uses of split bivs with their split pseudo register. This is
3517 for original instructions which remain after loop unrolling without
3521 remap_split_bivs (x
)
3524 register enum rtx_code code
;
3531 code
= GET_CODE (x
);
3546 /* If non-reduced/final-value givs were split, then this would also
3547 have to remap those givs also. */
3549 if (REGNO (x
) < max_reg_before_loop
3550 && reg_iv_type
[REGNO (x
)] == BASIC_INDUCT
)
3551 return reg_biv_class
[REGNO (x
)]->biv
->src_reg
;
3554 fmt
= GET_RTX_FORMAT (code
);
3555 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3558 XEXP (x
, i
) = remap_split_bivs (XEXP (x
, i
));
3562 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3563 XVECEXP (x
, i
, j
) = remap_split_bivs (XVECEXP (x
, i
, j
));
3569 /* If FIRST_UID is a set of REGNO, and FIRST_UID dominates LAST_UID (e.g.
3570 FIST_UID is always executed if LAST_UID is), then return 1. Otherwise
3571 return 0. COPY_START is where we can start looking for the insns
3572 FIRST_UID and LAST_UID. COPY_END is where we stop looking for these
3575 If there is no JUMP_INSN between LOOP_START and FIRST_UID, then FIRST_UID
3576 must dominate LAST_UID.
3578 If there is a CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3579 may not dominate LAST_UID.
3581 If there is no CODE_LABEL between FIRST_UID and LAST_UID, then FIRST_UID
3582 must dominate LAST_UID. */
3585 set_dominates_use (regno
, first_uid
, last_uid
, copy_start
, copy_end
)
3592 int passed_jump
= 0;
3593 rtx p
= NEXT_INSN (copy_start
);
3595 while (INSN_UID (p
) != first_uid
)
3597 if (GET_CODE (p
) == JUMP_INSN
)
3599 /* Could not find FIRST_UID. */
3605 /* Verify that FIRST_UID is an insn that entirely sets REGNO. */
3606 if (GET_RTX_CLASS (GET_CODE (p
)) != 'i'
3607 || ! dead_or_set_regno_p (p
, regno
))
3610 /* FIRST_UID is always executed. */
3611 if (passed_jump
== 0)
3614 while (INSN_UID (p
) != last_uid
)
3616 /* If we see a CODE_LABEL between FIRST_UID and LAST_UID, then we
3617 can not be sure that FIRST_UID dominates LAST_UID. */
3618 if (GET_CODE (p
) == CODE_LABEL
)
3620 /* Could not find LAST_UID, but we reached the end of the loop, so
3622 else if (p
== copy_end
)
3627 /* FIRST_UID is always executed if LAST_UID is executed. */