1 /* Loop unrolling and peeling.
2 Copyright (C) 2002-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
22 #include "coretypes.h"
26 #include "hard-reg-set.h"
28 #include "basic-block.h"
32 #include "hash-table.h"
37 /* This pass performs loop unrolling and peeling. We only perform these
38 optimizations on innermost loops (with single exception) because
39 the impact on performance is greatest here, and we want to avoid
40 unnecessary code size growth. The gain is caused by greater sequentiality
41 of code, better code to optimize for further passes and in some cases
42 by fewer testings of exit conditions. The main problem is code growth,
43 that impacts performance negatively due to effect of caches.
47 -- complete peeling of once-rolling loops; this is the above mentioned
48 exception, as this causes loop to be cancelled completely and
49 does not cause code growth
50 -- complete peeling of loops that roll (small) constant times.
51 -- simple peeling of first iterations of loops that do not roll much
52 (according to profile feedback)
53 -- unrolling of loops that roll constant times; this is almost always
54 win, as we get rid of exit condition tests.
55 -- unrolling of loops that roll number of times that we can compute
56 in runtime; we also get rid of exit condition tests here, but there
57 is the extra expense for calculating the number of iterations
58 -- simple unrolling of remaining loops; this is performed only if we
59 are asked to, as the gain is questionable in this case and often
60 it may even slow down the code
61 For more detailed descriptions of each of those, see comments at
62 appropriate function below.
64 There is a lot of parameters (defined and described in params.def) that
65 control how much we unroll/peel.
67 ??? A great problem is that we don't have a good way how to determine
68 how many times we should unroll the loop; the experiments I have made
69 showed that this choice may affect performance in order of several %.
72 /* Information about induction variables to split. */
76 rtx insn; /* The insn in that the induction variable occurs. */
77 rtx orig_var; /* The variable (register) for the IV before split. */
78 rtx base_var; /* The variable on that the values in the further
79 iterations are based. */
80 rtx step; /* Step of the induction variable. */
81 struct iv_to_split *next; /* Next entry in walking order. */
83 unsigned loc[3]; /* Location where the definition of the induction
84 variable occurs in the insn. For example if
85 N_LOC is 2, the expression is located at
86 XEXP (XEXP (single_set, loc[0]), loc[1]). */
89 /* Information about accumulators to expand. */
93 rtx insn; /* The insn in that the variable expansion occurs. */
94 rtx reg; /* The accumulator which is expanded. */
95 vec<rtx> var_expansions; /* The copies of the accumulator which is expanded. */
96 struct var_to_expand *next; /* Next entry in walking order. */
97 enum rtx_code op; /* The type of the accumulation - addition, subtraction
99 int expansion_count; /* Count the number of expansions generated so far. */
100 int reuse_expansion; /* The expansion we intend to reuse to expand
101 the accumulator. If REUSE_EXPANSION is 0 reuse
102 the original accumulator. Else use
103 var_expansions[REUSE_EXPANSION - 1]. */
106 /* Hashtable helper for iv_to_split. */
108 struct iv_split_hasher : typed_free_remove <iv_to_split>
110 typedef iv_to_split value_type;
111 typedef iv_to_split compare_type;
112 static inline hashval_t hash (const value_type *);
113 static inline bool equal (const value_type *, const compare_type *);
117 /* A hash function for information about insns to split. */
120 iv_split_hasher::hash (const value_type *ivts)
122 return (hashval_t) INSN_UID (ivts->insn);
125 /* An equality functions for information about insns to split. */
128 iv_split_hasher::equal (const value_type *i1, const compare_type *i2)
130 return i1->insn == i2->insn;
133 /* Hashtable helper for iv_to_split. */
135 struct var_expand_hasher : typed_free_remove <var_to_expand>
137 typedef var_to_expand value_type;
138 typedef var_to_expand compare_type;
139 static inline hashval_t hash (const value_type *);
140 static inline bool equal (const value_type *, const compare_type *);
143 /* Return a hash for VES. */
146 var_expand_hasher::hash (const value_type *ves)
148 return (hashval_t) INSN_UID (ves->insn);
151 /* Return true if I1 and I2 refer to the same instruction. */
154 var_expand_hasher::equal (const value_type *i1, const compare_type *i2)
156 return i1->insn == i2->insn;
159 /* Information about optimization applied in
160 the unrolled loop. */
164 hash_table <iv_split_hasher> insns_to_split; /* A hashtable of insns to
166 struct iv_to_split *iv_to_split_head; /* The first iv to split. */
167 struct iv_to_split **iv_to_split_tail; /* Pointer to the tail of the list. */
168 hash_table <var_expand_hasher> insns_with_var_to_expand; /* A hashtable of
169 insns with accumulators to expand. */
170 struct var_to_expand *var_to_expand_head; /* The first var to expand. */
171 struct var_to_expand **var_to_expand_tail; /* Pointer to the tail of the list. */
172 unsigned first_new_block; /* The first basic block that was
174 basic_block loop_exit; /* The loop exit basic block. */
175 basic_block loop_preheader; /* The loop preheader basic block. */
178 static void decide_unrolling_and_peeling (int);
179 static void peel_loops_completely (int);
180 static void decide_peel_simple (struct loop *, int);
181 static void decide_peel_once_rolling (struct loop *, int);
182 static void decide_peel_completely (struct loop *, int);
183 static void decide_unroll_stupid (struct loop *, int);
184 static void decide_unroll_constant_iterations (struct loop *, int);
185 static void decide_unroll_runtime_iterations (struct loop *, int);
186 static void peel_loop_simple (struct loop *);
187 static void peel_loop_completely (struct loop *);
188 static void unroll_loop_stupid (struct loop *);
189 static void unroll_loop_constant_iterations (struct loop *);
190 static void unroll_loop_runtime_iterations (struct loop *);
191 static struct opt_info *analyze_insns_in_loop (struct loop *);
192 static void opt_info_start_duplication (struct opt_info *);
193 static void apply_opt_in_copies (struct opt_info *, unsigned, bool, bool);
194 static void free_opt_info (struct opt_info *);
195 static struct var_to_expand *analyze_insn_to_expand_var (struct loop*, rtx);
196 static bool referenced_in_one_insn_in_loop_p (struct loop *, rtx, int *);
197 static struct iv_to_split *analyze_iv_to_split_insn (rtx);
198 static void expand_var_during_unrolling (struct var_to_expand *, rtx);
199 static void insert_var_expansion_initialization (struct var_to_expand *,
201 static void combine_var_copies_in_loop_exit (struct var_to_expand *,
203 static rtx get_expansion (struct var_to_expand *);
205 /* Emit a message summarizing the unroll or peel that will be
206 performed for LOOP, along with the loop's location LOCUS, if
207 appropriate given the dump or -fopt-info settings. */
210 report_unroll_peel (struct loop *loop, location_t locus)
212 struct niter_desc *desc;
214 int report_flags = MSG_OPTIMIZED_LOCATIONS | TDF_RTL | TDF_DETAILS;
216 if (loop->lpt_decision.decision == LPT_NONE)
219 if (!dump_enabled_p ())
222 /* In the special case where the loop never iterated, emit
223 a different message so that we don't report an unroll by 0.
224 This matches the equivalent message emitted during tree unrolling. */
225 if (loop->lpt_decision.decision == LPT_PEEL_COMPLETELY
226 && !loop->lpt_decision.times)
228 dump_printf_loc (report_flags, locus,
229 "loop turned into non-loop; it never loops.\n");
233 desc = get_simple_loop_desc (loop);
235 if (desc->const_iter)
236 niters = desc->niter;
237 else if (loop->header->count)
238 niters = expected_loop_iterations (loop);
240 if (loop->lpt_decision.decision == LPT_PEEL_COMPLETELY)
241 dump_printf_loc (report_flags, locus,
242 "loop with %d iterations completely unrolled",
243 loop->lpt_decision.times + 1);
245 dump_printf_loc (report_flags, locus,
247 (loop->lpt_decision.decision == LPT_PEEL_SIMPLE
248 ? "peeled" : "unrolled"),
249 loop->lpt_decision.times);
251 dump_printf (report_flags,
252 " (header execution count %d",
253 (int)loop->header->count);
254 if (loop->lpt_decision.decision == LPT_PEEL_COMPLETELY)
255 dump_printf (report_flags,
256 "%s%s iterations %d)",
257 profile_info ? ", " : " (",
258 desc->const_iter ? "const" : "average",
260 else if (profile_info)
261 dump_printf (report_flags, ")");
263 dump_printf (report_flags, "\n");
266 /* Unroll and/or peel (depending on FLAGS) LOOPS. */
268 unroll_and_peel_loops (int flags)
271 bool changed = false;
273 /* First perform complete loop peeling (it is almost surely a win,
274 and affects parameters for further decision a lot). */
275 peel_loops_completely (flags);
277 /* Now decide rest of unrolling and peeling. */
278 decide_unrolling_and_peeling (flags);
280 /* Scan the loops, inner ones first. */
281 FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
283 /* And perform the appropriate transformations. */
284 switch (loop->lpt_decision.decision)
286 case LPT_PEEL_COMPLETELY:
289 case LPT_PEEL_SIMPLE:
290 peel_loop_simple (loop);
293 case LPT_UNROLL_CONSTANT:
294 unroll_loop_constant_iterations (loop);
297 case LPT_UNROLL_RUNTIME:
298 unroll_loop_runtime_iterations (loop);
301 case LPT_UNROLL_STUPID:
302 unroll_loop_stupid (loop);
314 calculate_dominance_info (CDI_DOMINATORS);
315 fix_loop_structure (NULL);
321 /* Check whether exit of the LOOP is at the end of loop body. */
324 loop_exit_at_end_p (struct loop *loop)
326 struct niter_desc *desc = get_simple_loop_desc (loop);
329 if (desc->in_edge->dest != loop->latch)
332 /* Check that the latch is empty. */
333 FOR_BB_INSNS (loop->latch, insn)
335 if (NONDEBUG_INSN_P (insn))
342 /* Depending on FLAGS, check whether to peel loops completely and do so. */
344 peel_loops_completely (int flags)
347 bool changed = false;
349 /* Scan the loops, the inner ones first. */
350 FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
352 loop->lpt_decision.decision = LPT_NONE;
353 location_t locus = get_loop_location (loop);
355 if (dump_enabled_p ())
356 dump_printf_loc (TDF_RTL, locus,
357 ";; *** Considering loop %d at BB %d for "
358 "complete peeling ***\n",
359 loop->num, loop->header->index);
361 loop->ninsns = num_loop_insns (loop);
363 decide_peel_once_rolling (loop, flags);
364 if (loop->lpt_decision.decision == LPT_NONE)
365 decide_peel_completely (loop, flags);
367 if (loop->lpt_decision.decision == LPT_PEEL_COMPLETELY)
369 report_unroll_peel (loop, locus);
370 peel_loop_completely (loop);
377 calculate_dominance_info (CDI_DOMINATORS);
378 fix_loop_structure (NULL);
382 /* Decide whether unroll or peel loops (depending on FLAGS) and how much. */
384 decide_unrolling_and_peeling (int flags)
388 /* Scan the loops, inner ones first. */
389 FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
391 loop->lpt_decision.decision = LPT_NONE;
392 location_t locus = get_loop_location (loop);
394 if (dump_enabled_p ())
395 dump_printf_loc (TDF_RTL, locus,
396 ";; *** Considering loop %d at BB %d for "
397 "unrolling and peeling ***\n",
398 loop->num, loop->header->index);
400 /* Do not peel cold areas. */
401 if (optimize_loop_for_size_p (loop))
404 fprintf (dump_file, ";; Not considering loop, cold area\n");
408 /* Can the loop be manipulated? */
409 if (!can_duplicate_loop_p (loop))
413 ";; Not considering loop, cannot duplicate\n");
417 /* Skip non-innermost loops. */
421 fprintf (dump_file, ";; Not considering loop, is not innermost\n");
425 loop->ninsns = num_loop_insns (loop);
426 loop->av_ninsns = average_num_loop_insns (loop);
428 /* Try transformations one by one in decreasing order of
431 decide_unroll_constant_iterations (loop, flags);
432 if (loop->lpt_decision.decision == LPT_NONE)
433 decide_unroll_runtime_iterations (loop, flags);
434 if (loop->lpt_decision.decision == LPT_NONE)
435 decide_unroll_stupid (loop, flags);
436 if (loop->lpt_decision.decision == LPT_NONE)
437 decide_peel_simple (loop, flags);
439 report_unroll_peel (loop, locus);
443 /* Decide whether the LOOP is once rolling and suitable for complete
446 decide_peel_once_rolling (struct loop *loop, int flags ATTRIBUTE_UNUSED)
448 struct niter_desc *desc;
451 fprintf (dump_file, "\n;; Considering peeling once rolling loop\n");
453 /* Is the loop small enough? */
454 if ((unsigned) PARAM_VALUE (PARAM_MAX_ONCE_PEELED_INSNS) < loop->ninsns)
457 fprintf (dump_file, ";; Not considering loop, is too big\n");
461 /* Check for simple loops. */
462 desc = get_simple_loop_desc (loop);
464 /* Check number of iterations. */
470 && get_max_loop_iterations_int (loop) != 0))
474 ";; Unable to prove that the loop rolls exactly once\n");
479 loop->lpt_decision.decision = LPT_PEEL_COMPLETELY;
482 /* Decide whether the LOOP is suitable for complete peeling. */
484 decide_peel_completely (struct loop *loop, int flags ATTRIBUTE_UNUSED)
487 struct niter_desc *desc;
490 fprintf (dump_file, "\n;; Considering peeling completely\n");
492 /* Skip non-innermost loops. */
496 fprintf (dump_file, ";; Not considering loop, is not innermost\n");
500 /* Do not peel cold areas. */
501 if (optimize_loop_for_size_p (loop))
504 fprintf (dump_file, ";; Not considering loop, cold area\n");
508 /* Can the loop be manipulated? */
509 if (!can_duplicate_loop_p (loop))
513 ";; Not considering loop, cannot duplicate\n");
517 /* npeel = number of iterations to peel. */
518 npeel = PARAM_VALUE (PARAM_MAX_COMPLETELY_PEELED_INSNS) / loop->ninsns;
519 if (npeel > (unsigned) PARAM_VALUE (PARAM_MAX_COMPLETELY_PEEL_TIMES))
520 npeel = PARAM_VALUE (PARAM_MAX_COMPLETELY_PEEL_TIMES);
522 /* Is the loop small enough? */
526 fprintf (dump_file, ";; Not considering loop, is too big\n");
530 /* Check for simple loops. */
531 desc = get_simple_loop_desc (loop);
533 /* Check number of iterations. */
541 ";; Unable to prove that the loop iterates constant times\n");
545 if (desc->niter > npeel - 1)
550 ";; Not peeling loop completely, rolls too much (");
551 fprintf (dump_file, HOST_WIDEST_INT_PRINT_DEC, desc->niter);
552 fprintf (dump_file, " iterations > %d [maximum peelings])\n", npeel);
558 loop->lpt_decision.decision = LPT_PEEL_COMPLETELY;
561 /* Peel all iterations of LOOP, remove exit edges and cancel the loop
562 completely. The transformation done:
564 for (i = 0; i < 4; i++)
576 peel_loop_completely (struct loop *loop)
579 unsigned HOST_WIDE_INT npeel;
582 struct niter_desc *desc = get_simple_loop_desc (loop);
583 struct opt_info *opt_info = NULL;
591 wont_exit = sbitmap_alloc (npeel + 1);
592 bitmap_ones (wont_exit);
593 bitmap_clear_bit (wont_exit, 0);
594 if (desc->noloop_assumptions)
595 bitmap_clear_bit (wont_exit, 1);
597 auto_vec<edge> remove_edges;
598 if (flag_split_ivs_in_unroller)
599 opt_info = analyze_insns_in_loop (loop);
601 opt_info_start_duplication (opt_info);
602 ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
604 wont_exit, desc->out_edge,
606 DLTHE_FLAG_UPDATE_FREQ
607 | DLTHE_FLAG_COMPLETTE_PEEL
609 ? DLTHE_RECORD_COPY_NUMBER : 0));
616 apply_opt_in_copies (opt_info, npeel, false, true);
617 free_opt_info (opt_info);
620 /* Remove the exit edges. */
621 FOR_EACH_VEC_ELT (remove_edges, i, ein)
626 free_simple_loop_desc (loop);
628 /* Now remove the unreachable part of the last iteration and cancel
633 fprintf (dump_file, ";; Peeled loop completely, %d times\n", (int) npeel);
636 /* Decide whether to unroll LOOP iterating constant number of times
640 decide_unroll_constant_iterations (struct loop *loop, int flags)
642 unsigned nunroll, nunroll_by_av, best_copies, best_unroll = 0, n_copies, i;
643 struct niter_desc *desc;
644 widest_int iterations;
646 if (!(flags & UAP_UNROLL))
648 /* We were not asked to, just return back silently. */
654 "\n;; Considering unrolling loop with constant "
655 "number of iterations\n");
657 /* nunroll = total number of copies of the original loop body in
658 unrolled loop (i.e. if it is 2, we have to duplicate loop body once. */
659 nunroll = PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS) / loop->ninsns;
661 = PARAM_VALUE (PARAM_MAX_AVERAGE_UNROLLED_INSNS) / loop->av_ninsns;
662 if (nunroll > nunroll_by_av)
663 nunroll = nunroll_by_av;
664 if (nunroll > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLL_TIMES))
665 nunroll = PARAM_VALUE (PARAM_MAX_UNROLL_TIMES);
667 if (targetm.loop_unroll_adjust)
668 nunroll = targetm.loop_unroll_adjust (nunroll, loop);
670 /* Skip big loops. */
674 fprintf (dump_file, ";; Not considering loop, is too big\n");
678 /* Check for simple loops. */
679 desc = get_simple_loop_desc (loop);
681 /* Check number of iterations. */
682 if (!desc->simple_p || !desc->const_iter || desc->assumptions)
686 ";; Unable to prove that the loop iterates constant times\n");
690 /* Check whether the loop rolls enough to consider.
691 Consult also loop bounds and profile; in the case the loop has more
692 than one exit it may well loop less than determined maximal number
694 if (desc->niter < 2 * nunroll
695 || ((get_estimated_loop_iterations (loop, &iterations)
696 || get_max_loop_iterations (loop, &iterations))
697 && wi::ltu_p (iterations, 2 * nunroll)))
700 fprintf (dump_file, ";; Not unrolling loop, doesn't roll\n");
704 /* Success; now compute number of iterations to unroll. We alter
705 nunroll so that as few as possible copies of loop body are
706 necessary, while still not decreasing the number of unrollings
707 too much (at most by 1). */
708 best_copies = 2 * nunroll + 10;
711 if (i - 1 >= desc->niter)
714 for (; i >= nunroll - 1; i--)
716 unsigned exit_mod = desc->niter % (i + 1);
718 if (!loop_exit_at_end_p (loop))
719 n_copies = exit_mod + i + 1;
720 else if (exit_mod != (unsigned) i
721 || desc->noloop_assumptions != NULL_RTX)
722 n_copies = exit_mod + i + 2;
726 if (n_copies < best_copies)
728 best_copies = n_copies;
733 loop->lpt_decision.decision = LPT_UNROLL_CONSTANT;
734 loop->lpt_decision.times = best_unroll;
737 /* Unroll LOOP with constant number of iterations LOOP->LPT_DECISION.TIMES times.
738 The transformation does this:
740 for (i = 0; i < 102; i++)
743 ==> (LOOP->LPT_DECISION.TIMES == 3)
757 unroll_loop_constant_iterations (struct loop *loop)
759 unsigned HOST_WIDE_INT niter;
764 unsigned max_unroll = loop->lpt_decision.times;
765 struct niter_desc *desc = get_simple_loop_desc (loop);
766 bool exit_at_end = loop_exit_at_end_p (loop);
767 struct opt_info *opt_info = NULL;
772 /* Should not get here (such loop should be peeled instead). */
773 gcc_assert (niter > max_unroll + 1);
775 exit_mod = niter % (max_unroll + 1);
777 wont_exit = sbitmap_alloc (max_unroll + 1);
778 bitmap_ones (wont_exit);
780 auto_vec<edge> remove_edges;
781 if (flag_split_ivs_in_unroller
782 || flag_variable_expansion_in_unroller)
783 opt_info = analyze_insns_in_loop (loop);
787 /* The exit is not at the end of the loop; leave exit test
788 in the first copy, so that the loops that start with test
789 of exit condition have continuous body after unrolling. */
792 fprintf (dump_file, ";; Condition at beginning of loop.\n");
794 /* Peel exit_mod iterations. */
795 bitmap_clear_bit (wont_exit, 0);
796 if (desc->noloop_assumptions)
797 bitmap_clear_bit (wont_exit, 1);
801 opt_info_start_duplication (opt_info);
802 ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
804 wont_exit, desc->out_edge,
806 DLTHE_FLAG_UPDATE_FREQ
807 | (opt_info && exit_mod > 1
808 ? DLTHE_RECORD_COPY_NUMBER
812 if (opt_info && exit_mod > 1)
813 apply_opt_in_copies (opt_info, exit_mod, false, false);
815 desc->noloop_assumptions = NULL_RTX;
816 desc->niter -= exit_mod;
817 loop->nb_iterations_upper_bound -= exit_mod;
818 if (loop->any_estimate
819 && wi::leu_p (exit_mod, loop->nb_iterations_estimate))
820 loop->nb_iterations_estimate -= exit_mod;
822 loop->any_estimate = false;
825 bitmap_set_bit (wont_exit, 1);
829 /* Leave exit test in last copy, for the same reason as above if
830 the loop tests the condition at the end of loop body. */
833 fprintf (dump_file, ";; Condition at end of loop.\n");
835 /* We know that niter >= max_unroll + 2; so we do not need to care of
836 case when we would exit before reaching the loop. So just peel
837 exit_mod + 1 iterations. */
838 if (exit_mod != max_unroll
839 || desc->noloop_assumptions)
841 bitmap_clear_bit (wont_exit, 0);
842 if (desc->noloop_assumptions)
843 bitmap_clear_bit (wont_exit, 1);
845 opt_info_start_duplication (opt_info);
846 ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
848 wont_exit, desc->out_edge,
850 DLTHE_FLAG_UPDATE_FREQ
851 | (opt_info && exit_mod > 0
852 ? DLTHE_RECORD_COPY_NUMBER
856 if (opt_info && exit_mod > 0)
857 apply_opt_in_copies (opt_info, exit_mod + 1, false, false);
859 desc->niter -= exit_mod + 1;
860 loop->nb_iterations_upper_bound -= exit_mod + 1;
861 if (loop->any_estimate
862 && wi::leu_p (exit_mod + 1, loop->nb_iterations_estimate))
863 loop->nb_iterations_estimate -= exit_mod + 1;
865 loop->any_estimate = false;
866 desc->noloop_assumptions = NULL_RTX;
868 bitmap_set_bit (wont_exit, 0);
869 bitmap_set_bit (wont_exit, 1);
872 bitmap_clear_bit (wont_exit, max_unroll);
875 /* Now unroll the loop. */
877 opt_info_start_duplication (opt_info);
878 ok = duplicate_loop_to_header_edge (loop, loop_latch_edge (loop),
880 wont_exit, desc->out_edge,
882 DLTHE_FLAG_UPDATE_FREQ
884 ? DLTHE_RECORD_COPY_NUMBER
890 apply_opt_in_copies (opt_info, max_unroll, true, true);
891 free_opt_info (opt_info);
898 basic_block exit_block = get_bb_copy (desc->in_edge->src);
899 /* Find a new in and out edge; they are in the last copy we have made. */
901 if (EDGE_SUCC (exit_block, 0)->dest == desc->out_edge->dest)
903 desc->out_edge = EDGE_SUCC (exit_block, 0);
904 desc->in_edge = EDGE_SUCC (exit_block, 1);
908 desc->out_edge = EDGE_SUCC (exit_block, 1);
909 desc->in_edge = EDGE_SUCC (exit_block, 0);
913 desc->niter /= max_unroll + 1;
914 loop->nb_iterations_upper_bound
915 = wi::udiv_trunc (loop->nb_iterations_upper_bound, max_unroll + 1);
916 if (loop->any_estimate)
917 loop->nb_iterations_estimate
918 = wi::udiv_trunc (loop->nb_iterations_estimate, max_unroll + 1);
919 desc->niter_expr = GEN_INT (desc->niter);
921 /* Remove the edges. */
922 FOR_EACH_VEC_ELT (remove_edges, i, e)
927 ";; Unrolled loop %d times, constant # of iterations %i insns\n",
928 max_unroll, num_loop_insns (loop));
931 /* Decide whether to unroll LOOP iterating runtime computable number of times
934 decide_unroll_runtime_iterations (struct loop *loop, int flags)
936 unsigned nunroll, nunroll_by_av, i;
937 struct niter_desc *desc;
938 widest_int iterations;
940 if (!(flags & UAP_UNROLL))
942 /* We were not asked to, just return back silently. */
948 "\n;; Considering unrolling loop with runtime "
949 "computable number of iterations\n");
951 /* nunroll = total number of copies of the original loop body in
952 unrolled loop (i.e. if it is 2, we have to duplicate loop body once. */
953 nunroll = PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS) / loop->ninsns;
954 nunroll_by_av = PARAM_VALUE (PARAM_MAX_AVERAGE_UNROLLED_INSNS) / loop->av_ninsns;
955 if (nunroll > nunroll_by_av)
956 nunroll = nunroll_by_av;
957 if (nunroll > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLL_TIMES))
958 nunroll = PARAM_VALUE (PARAM_MAX_UNROLL_TIMES);
960 if (targetm.loop_unroll_adjust)
961 nunroll = targetm.loop_unroll_adjust (nunroll, loop);
963 /* Skip big loops. */
967 fprintf (dump_file, ";; Not considering loop, is too big\n");
971 /* Check for simple loops. */
972 desc = get_simple_loop_desc (loop);
974 /* Check simpleness. */
975 if (!desc->simple_p || desc->assumptions)
979 ";; Unable to prove that the number of iterations "
980 "can be counted in runtime\n");
984 if (desc->const_iter)
987 fprintf (dump_file, ";; Loop iterates constant times\n");
991 /* Check whether the loop rolls. */
992 if ((get_estimated_loop_iterations (loop, &iterations)
993 || get_max_loop_iterations (loop, &iterations))
994 && wi::ltu_p (iterations, 2 * nunroll))
997 fprintf (dump_file, ";; Not unrolling loop, doesn't roll\n");
1001 /* Success; now force nunroll to be power of 2, as we are unable to
1002 cope with overflows in computation of number of iterations. */
1003 for (i = 1; 2 * i <= nunroll; i *= 2)
1006 loop->lpt_decision.decision = LPT_UNROLL_RUNTIME;
1007 loop->lpt_decision.times = i - 1;
1010 /* Splits edge E and inserts the sequence of instructions INSNS on it, and
1011 returns the newly created block. If INSNS is NULL_RTX, nothing is changed
1012 and NULL is returned instead. */
1015 split_edge_and_insert (edge e, rtx insns)
1021 bb = split_edge (e);
1022 emit_insn_after (insns, BB_END (bb));
1024 /* ??? We used to assume that INSNS can contain control flow insns, and
1025 that we had to try to find sub basic blocks in BB to maintain a valid
1026 CFG. For this purpose we used to set the BB_SUPERBLOCK flag on BB
1027 and call break_superblocks when going out of cfglayout mode. But it
1028 turns out that this never happens; and that if it does ever happen,
1029 the TODO_verify_flow at the end of the RTL loop passes would fail.
1031 There are two reasons why we expected we could have control flow insns
1032 in INSNS. The first is when a comparison has to be done in parts, and
1033 the second is when the number of iterations is computed for loops with
1034 the number of iterations known at runtime. In both cases, test cases
1035 to get control flow in INSNS appear to be impossible to construct:
1037 * If do_compare_rtx_and_jump needs several branches to do comparison
1038 in a mode that needs comparison by parts, we cannot analyze the
1039 number of iterations of the loop, and we never get to unrolling it.
1041 * The code in expand_divmod that was suspected to cause creation of
1042 branching code seems to be only accessed for signed division. The
1043 divisions used by # of iterations analysis are always unsigned.
1044 Problems might arise on architectures that emits branching code
1045 for some operations that may appear in the unroller (especially
1046 for division), but we have no such architectures.
1048 Considering all this, it was decided that we should for now assume
1049 that INSNS can in theory contain control flow insns, but in practice
1050 it never does. So we don't handle the theoretical case, and should
1051 a real failure ever show up, we have a pretty good clue for how to
1057 /* Unroll LOOP for which we are able to count number of iterations in runtime
1058 LOOP->LPT_DECISION.TIMES times. The transformation does this (with some
1059 extra care for case n < 0):
1061 for (i = 0; i < n; i++)
1064 ==> (LOOP->LPT_DECISION.TIMES == 3)
1089 unroll_loop_runtime_iterations (struct loop *loop)
1091 rtx old_niter, niter, init_code, branch_code, tmp;
1093 basic_block preheader, *body, swtch, ezc_swtch;
1098 bool extra_zero_check, last_may_exit;
1099 unsigned max_unroll = loop->lpt_decision.times;
1100 struct niter_desc *desc = get_simple_loop_desc (loop);
1101 bool exit_at_end = loop_exit_at_end_p (loop);
1102 struct opt_info *opt_info = NULL;
1105 if (flag_split_ivs_in_unroller
1106 || flag_variable_expansion_in_unroller)
1107 opt_info = analyze_insns_in_loop (loop);
1109 /* Remember blocks whose dominators will have to be updated. */
1110 auto_vec<basic_block> dom_bbs;
1112 body = get_loop_body (loop);
1113 for (i = 0; i < loop->num_nodes; i++)
1115 vec<basic_block> ldom;
1118 ldom = get_dominated_by (CDI_DOMINATORS, body[i]);
1119 FOR_EACH_VEC_ELT (ldom, j, bb)
1120 if (!flow_bb_inside_loop_p (loop, bb))
1121 dom_bbs.safe_push (bb);
1129 /* Leave exit in first copy (for explanation why see comment in
1130 unroll_loop_constant_iterations). */
1132 n_peel = max_unroll - 1;
1133 extra_zero_check = true;
1134 last_may_exit = false;
1138 /* Leave exit in last copy (for explanation why see comment in
1139 unroll_loop_constant_iterations). */
1140 may_exit_copy = max_unroll;
1141 n_peel = max_unroll;
1142 extra_zero_check = false;
1143 last_may_exit = true;
1146 /* Get expression for number of iterations. */
1148 old_niter = niter = gen_reg_rtx (desc->mode);
1149 tmp = force_operand (copy_rtx (desc->niter_expr), niter);
1151 emit_move_insn (niter, tmp);
1153 /* Count modulo by ANDing it with max_unroll; we use the fact that
1154 the number of unrollings is a power of two, and thus this is correct
1155 even if there is overflow in the computation. */
1156 niter = expand_simple_binop (desc->mode, AND,
1157 niter, gen_int_mode (max_unroll, desc->mode),
1158 NULL_RTX, 0, OPTAB_LIB_WIDEN);
1160 init_code = get_insns ();
1162 unshare_all_rtl_in_chain (init_code);
1164 /* Precondition the loop. */
1165 split_edge_and_insert (loop_preheader_edge (loop), init_code);
1167 auto_vec<edge> remove_edges;
1169 wont_exit = sbitmap_alloc (max_unroll + 2);
1171 /* Peel the first copy of loop body (almost always we must leave exit test
1172 here; the only exception is when we have extra zero check and the number
1173 of iterations is reliable. Also record the place of (possible) extra
1175 bitmap_clear (wont_exit);
1176 if (extra_zero_check
1177 && !desc->noloop_assumptions)
1178 bitmap_set_bit (wont_exit, 1);
1179 ezc_swtch = loop_preheader_edge (loop)->src;
1180 ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
1181 1, wont_exit, desc->out_edge,
1183 DLTHE_FLAG_UPDATE_FREQ);
1186 /* Record the place where switch will be built for preconditioning. */
1187 swtch = split_edge (loop_preheader_edge (loop));
1189 for (i = 0; i < n_peel; i++)
1191 /* Peel the copy. */
1192 bitmap_clear (wont_exit);
1193 if (i != n_peel - 1 || !last_may_exit)
1194 bitmap_set_bit (wont_exit, 1);
1195 ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
1196 1, wont_exit, desc->out_edge,
1198 DLTHE_FLAG_UPDATE_FREQ);
1201 /* Create item for switch. */
1202 j = n_peel - i - (extra_zero_check ? 0 : 1);
1203 p = REG_BR_PROB_BASE / (i + 2);
1205 preheader = split_edge (loop_preheader_edge (loop));
1206 branch_code = compare_and_jump_seq (copy_rtx (niter), GEN_INT (j), EQ,
1207 block_label (preheader), p,
1210 /* We rely on the fact that the compare and jump cannot be optimized out,
1211 and hence the cfg we create is correct. */
1212 gcc_assert (branch_code != NULL_RTX);
1214 swtch = split_edge_and_insert (single_pred_edge (swtch), branch_code);
1215 set_immediate_dominator (CDI_DOMINATORS, preheader, swtch);
1216 single_pred_edge (swtch)->probability = REG_BR_PROB_BASE - p;
1217 e = make_edge (swtch, preheader,
1218 single_succ_edge (swtch)->flags & EDGE_IRREDUCIBLE_LOOP);
1219 e->count = RDIV (preheader->count * REG_BR_PROB_BASE, p);
1223 if (extra_zero_check)
1225 /* Add branch for zero iterations. */
1226 p = REG_BR_PROB_BASE / (max_unroll + 1);
1228 preheader = split_edge (loop_preheader_edge (loop));
1229 branch_code = compare_and_jump_seq (copy_rtx (niter), const0_rtx, EQ,
1230 block_label (preheader), p,
1232 gcc_assert (branch_code != NULL_RTX);
1234 swtch = split_edge_and_insert (single_succ_edge (swtch), branch_code);
1235 set_immediate_dominator (CDI_DOMINATORS, preheader, swtch);
1236 single_succ_edge (swtch)->probability = REG_BR_PROB_BASE - p;
1237 e = make_edge (swtch, preheader,
1238 single_succ_edge (swtch)->flags & EDGE_IRREDUCIBLE_LOOP);
1239 e->count = RDIV (preheader->count * REG_BR_PROB_BASE, p);
1243 /* Recount dominators for outer blocks. */
1244 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, false);
1246 /* And unroll loop. */
1248 bitmap_ones (wont_exit);
1249 bitmap_clear_bit (wont_exit, may_exit_copy);
1250 opt_info_start_duplication (opt_info);
1252 ok = duplicate_loop_to_header_edge (loop, loop_latch_edge (loop),
1254 wont_exit, desc->out_edge,
1256 DLTHE_FLAG_UPDATE_FREQ
1258 ? DLTHE_RECORD_COPY_NUMBER
1264 apply_opt_in_copies (opt_info, max_unroll, true, true);
1265 free_opt_info (opt_info);
1272 basic_block exit_block = get_bb_copy (desc->in_edge->src);
1273 /* Find a new in and out edge; they are in the last copy we have
1276 if (EDGE_SUCC (exit_block, 0)->dest == desc->out_edge->dest)
1278 desc->out_edge = EDGE_SUCC (exit_block, 0);
1279 desc->in_edge = EDGE_SUCC (exit_block, 1);
1283 desc->out_edge = EDGE_SUCC (exit_block, 1);
1284 desc->in_edge = EDGE_SUCC (exit_block, 0);
1288 /* Remove the edges. */
1289 FOR_EACH_VEC_ELT (remove_edges, i, e)
1292 /* We must be careful when updating the number of iterations due to
1293 preconditioning and the fact that the value must be valid at entry
1294 of the loop. After passing through the above code, we see that
1295 the correct new number of iterations is this: */
1296 gcc_assert (!desc->const_iter);
1298 simplify_gen_binary (UDIV, desc->mode, old_niter,
1299 gen_int_mode (max_unroll + 1, desc->mode));
1300 loop->nb_iterations_upper_bound
1301 = wi::udiv_trunc (loop->nb_iterations_upper_bound, max_unroll + 1);
1302 if (loop->any_estimate)
1303 loop->nb_iterations_estimate
1304 = wi::udiv_trunc (loop->nb_iterations_estimate, max_unroll + 1);
1308 simplify_gen_binary (MINUS, desc->mode, desc->niter_expr, const1_rtx);
1309 desc->noloop_assumptions = NULL_RTX;
1310 --loop->nb_iterations_upper_bound;
1311 if (loop->any_estimate
1312 && loop->nb_iterations_estimate != 0)
1313 --loop->nb_iterations_estimate;
1315 loop->any_estimate = false;
1320 ";; Unrolled loop %d times, counting # of iterations "
1321 "in runtime, %i insns\n",
1322 max_unroll, num_loop_insns (loop));
1325 /* Decide whether to simply peel LOOP and how much. */
1327 decide_peel_simple (struct loop *loop, int flags)
1330 widest_int iterations;
1332 if (!(flags & UAP_PEEL))
1334 /* We were not asked to, just return back silently. */
1339 fprintf (dump_file, "\n;; Considering simply peeling loop\n");
1341 /* npeel = number of iterations to peel. */
1342 npeel = PARAM_VALUE (PARAM_MAX_PEELED_INSNS) / loop->ninsns;
1343 if (npeel > (unsigned) PARAM_VALUE (PARAM_MAX_PEEL_TIMES))
1344 npeel = PARAM_VALUE (PARAM_MAX_PEEL_TIMES);
1346 /* Skip big loops. */
1350 fprintf (dump_file, ";; Not considering loop, is too big\n");
1354 /* Do not simply peel loops with branches inside -- it increases number
1356 Exception is when we do have profile and we however have good chance
1357 to peel proper number of iterations loop will iterate in practice.
1358 TODO: this heuristic needs tunning; while for complette unrolling
1359 the branch inside loop mostly eliminates any improvements, for
1360 peeling it is not the case. Also a function call inside loop is
1361 also branch from branch prediction POV (and probably better reason
1362 to not unroll/peel). */
1363 if (num_loop_branches (loop) > 1
1364 && profile_status_for_fn (cfun) != PROFILE_READ)
1367 fprintf (dump_file, ";; Not peeling, contains branches\n");
1371 /* If we have realistic estimate on number of iterations, use it. */
1372 if (get_estimated_loop_iterations (loop, &iterations))
1374 if (wi::leu_p (npeel, iterations))
1378 fprintf (dump_file, ";; Not peeling loop, rolls too much (");
1379 fprintf (dump_file, HOST_WIDEST_INT_PRINT_DEC,
1380 (HOST_WIDEST_INT) (iterations.to_shwi () + 1));
1381 fprintf (dump_file, " iterations > %d [maximum peelings])\n",
1386 npeel = iterations.to_shwi () + 1;
1388 /* If we have small enough bound on iterations, we can still peel (completely
1390 else if (get_max_loop_iterations (loop, &iterations)
1391 && wi::ltu_p (iterations, npeel))
1392 npeel = iterations.to_shwi () + 1;
1395 /* For now we have no good heuristics to decide whether loop peeling
1396 will be effective, so disable it. */
1399 ";; Not peeling loop, no evidence it will be profitable\n");
1404 loop->lpt_decision.decision = LPT_PEEL_SIMPLE;
1405 loop->lpt_decision.times = npeel;
1408 /* Peel a LOOP LOOP->LPT_DECISION.TIMES times. The transformation does this:
1413 ==> (LOOP->LPT_DECISION.TIMES == 3)
1415 if (!cond) goto end;
1417 if (!cond) goto end;
1419 if (!cond) goto end;
1426 peel_loop_simple (struct loop *loop)
1429 unsigned npeel = loop->lpt_decision.times;
1430 struct niter_desc *desc = get_simple_loop_desc (loop);
1431 struct opt_info *opt_info = NULL;
1434 if (flag_split_ivs_in_unroller && npeel > 1)
1435 opt_info = analyze_insns_in_loop (loop);
1437 wont_exit = sbitmap_alloc (npeel + 1);
1438 bitmap_clear (wont_exit);
1440 opt_info_start_duplication (opt_info);
1442 ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
1443 npeel, wont_exit, NULL,
1444 NULL, DLTHE_FLAG_UPDATE_FREQ
1446 ? DLTHE_RECORD_COPY_NUMBER
1454 apply_opt_in_copies (opt_info, npeel, false, false);
1455 free_opt_info (opt_info);
1460 if (desc->const_iter)
1462 desc->niter -= npeel;
1463 desc->niter_expr = GEN_INT (desc->niter);
1464 desc->noloop_assumptions = NULL_RTX;
1468 /* We cannot just update niter_expr, as its value might be clobbered
1469 inside loop. We could handle this by counting the number into
1470 temporary just like we do in runtime unrolling, but it does not
1472 free_simple_loop_desc (loop);
1476 fprintf (dump_file, ";; Peeling loop %d times\n", npeel);
1479 /* Decide whether to unroll LOOP stupidly and how much. */
1481 decide_unroll_stupid (struct loop *loop, int flags)
1483 unsigned nunroll, nunroll_by_av, i;
1484 struct niter_desc *desc;
1485 widest_int iterations;
1487 if (!(flags & UAP_UNROLL_ALL))
1489 /* We were not asked to, just return back silently. */
1494 fprintf (dump_file, "\n;; Considering unrolling loop stupidly\n");
1496 /* nunroll = total number of copies of the original loop body in
1497 unrolled loop (i.e. if it is 2, we have to duplicate loop body once. */
1498 nunroll = PARAM_VALUE (PARAM_MAX_UNROLLED_INSNS) / loop->ninsns;
1500 = PARAM_VALUE (PARAM_MAX_AVERAGE_UNROLLED_INSNS) / loop->av_ninsns;
1501 if (nunroll > nunroll_by_av)
1502 nunroll = nunroll_by_av;
1503 if (nunroll > (unsigned) PARAM_VALUE (PARAM_MAX_UNROLL_TIMES))
1504 nunroll = PARAM_VALUE (PARAM_MAX_UNROLL_TIMES);
1506 if (targetm.loop_unroll_adjust)
1507 nunroll = targetm.loop_unroll_adjust (nunroll, loop);
1509 /* Skip big loops. */
1513 fprintf (dump_file, ";; Not considering loop, is too big\n");
1517 /* Check for simple loops. */
1518 desc = get_simple_loop_desc (loop);
1520 /* Check simpleness. */
1521 if (desc->simple_p && !desc->assumptions)
1524 fprintf (dump_file, ";; The loop is simple\n");
1528 /* Do not unroll loops with branches inside -- it increases number
1530 TODO: this heuristic needs tunning; call inside the loop body
1531 is also relatively good reason to not unroll. */
1532 if (num_loop_branches (loop) > 1)
1535 fprintf (dump_file, ";; Not unrolling, contains branches\n");
1539 /* Check whether the loop rolls. */
1540 if ((get_estimated_loop_iterations (loop, &iterations)
1541 || get_max_loop_iterations (loop, &iterations))
1542 && wi::ltu_p (iterations, 2 * nunroll))
1545 fprintf (dump_file, ";; Not unrolling loop, doesn't roll\n");
1549 /* Success. Now force nunroll to be power of 2, as it seems that this
1550 improves results (partially because of better alignments, partially
1551 because of some dark magic). */
1552 for (i = 1; 2 * i <= nunroll; i *= 2)
1555 loop->lpt_decision.decision = LPT_UNROLL_STUPID;
1556 loop->lpt_decision.times = i - 1;
1559 /* Unroll a LOOP LOOP->LPT_DECISION.TIMES times. The transformation does this:
1564 ==> (LOOP->LPT_DECISION.TIMES == 3)
1578 unroll_loop_stupid (struct loop *loop)
1581 unsigned nunroll = loop->lpt_decision.times;
1582 struct niter_desc *desc = get_simple_loop_desc (loop);
1583 struct opt_info *opt_info = NULL;
1586 if (flag_split_ivs_in_unroller
1587 || flag_variable_expansion_in_unroller)
1588 opt_info = analyze_insns_in_loop (loop);
1591 wont_exit = sbitmap_alloc (nunroll + 1);
1592 bitmap_clear (wont_exit);
1593 opt_info_start_duplication (opt_info);
1595 ok = duplicate_loop_to_header_edge (loop, loop_latch_edge (loop),
1598 DLTHE_FLAG_UPDATE_FREQ
1600 ? DLTHE_RECORD_COPY_NUMBER
1606 apply_opt_in_copies (opt_info, nunroll, true, true);
1607 free_opt_info (opt_info);
1614 /* We indeed may get here provided that there are nontrivial assumptions
1615 for a loop to be really simple. We could update the counts, but the
1616 problem is that we are unable to decide which exit will be taken
1617 (not really true in case the number of iterations is constant,
1618 but no one will do anything with this information, so we do not
1620 desc->simple_p = false;
1624 fprintf (dump_file, ";; Unrolled loop %d times, %i insns\n",
1625 nunroll, num_loop_insns (loop));
1628 /* Returns true if REG is referenced in one nondebug insn in LOOP.
1629 Set *DEBUG_USES to the number of debug insns that reference the
1633 referenced_in_one_insn_in_loop_p (struct loop *loop, rtx reg,
1636 basic_block *body, bb;
1641 body = get_loop_body (loop);
1642 for (i = 0; i < loop->num_nodes; i++)
1646 FOR_BB_INSNS (bb, insn)
1647 if (!rtx_referenced_p (reg, insn))
1649 else if (DEBUG_INSN_P (insn))
1651 else if (++count_ref > 1)
1655 return (count_ref == 1);
1658 /* Reset the DEBUG_USES debug insns in LOOP that reference REG. */
1661 reset_debug_uses_in_loop (struct loop *loop, rtx reg, int debug_uses)
1663 basic_block *body, bb;
1667 body = get_loop_body (loop);
1668 for (i = 0; debug_uses && i < loop->num_nodes; i++)
1672 FOR_BB_INSNS (bb, insn)
1673 if (!DEBUG_INSN_P (insn) || !rtx_referenced_p (reg, insn))
1677 validate_change (insn, &INSN_VAR_LOCATION_LOC (insn),
1678 gen_rtx_UNKNOWN_VAR_LOC (), 0);
1686 /* Determine whether INSN contains an accumulator
1687 which can be expanded into separate copies,
1688 one for each copy of the LOOP body.
1690 for (i = 0 ; i < n; i++)
1704 Return NULL if INSN contains no opportunity for expansion of accumulator.
1705 Otherwise, allocate a VAR_TO_EXPAND structure, fill it with the relevant
1706 information and return a pointer to it.
1709 static struct var_to_expand *
1710 analyze_insn_to_expand_var (struct loop *loop, rtx insn)
1713 struct var_to_expand *ves;
1718 set = single_set (insn);
1722 dest = SET_DEST (set);
1723 src = SET_SRC (set);
1724 code = GET_CODE (src);
1726 if (code != PLUS && code != MINUS && code != MULT && code != FMA)
1729 if (FLOAT_MODE_P (GET_MODE (dest)))
1731 if (!flag_associative_math)
1733 /* In the case of FMA, we're also changing the rounding. */
1734 if (code == FMA && !flag_unsafe_math_optimizations)
1738 /* Hmm, this is a bit paradoxical. We know that INSN is a valid insn
1739 in MD. But if there is no optab to generate the insn, we can not
1740 perform the variable expansion. This can happen if an MD provides
1741 an insn but not a named pattern to generate it, for example to avoid
1742 producing code that needs additional mode switches like for x87/mmx.
1744 So we check have_insn_for which looks for an optab for the operation
1745 in SRC. If it doesn't exist, we can't perform the expansion even
1746 though INSN is valid. */
1747 if (!have_insn_for (code, GET_MODE (src)))
1751 && !(GET_CODE (dest) == SUBREG
1752 && REG_P (SUBREG_REG (dest))))
1755 /* Find the accumulator use within the operation. */
1758 /* We only support accumulation via FMA in the ADD position. */
1759 if (!rtx_equal_p (dest, XEXP (src, 2)))
1763 else if (rtx_equal_p (dest, XEXP (src, 0)))
1765 else if (rtx_equal_p (dest, XEXP (src, 1)))
1767 /* The method of expansion that we are using; which includes the
1768 initialization of the expansions with zero and the summation of
1769 the expansions at the end of the computation will yield wrong
1770 results for (x = something - x) thus avoid using it in that case. */
1778 /* It must not otherwise be used. */
1781 if (rtx_referenced_p (dest, XEXP (src, 0))
1782 || rtx_referenced_p (dest, XEXP (src, 1)))
1785 else if (rtx_referenced_p (dest, XEXP (src, 1 - accum_pos)))
1788 /* It must be used in exactly one insn. */
1789 if (!referenced_in_one_insn_in_loop_p (loop, dest, &debug_uses))
1794 fprintf (dump_file, "\n;; Expanding Accumulator ");
1795 print_rtl (dump_file, dest);
1796 fprintf (dump_file, "\n");
1800 /* Instead of resetting the debug insns, we could replace each
1801 debug use in the loop with the sum or product of all expanded
1802 accummulators. Since we'll only know of all expansions at the
1803 end, we'd have to keep track of which vars_to_expand a debug
1804 insn in the loop references, take note of each copy of the
1805 debug insn during unrolling, and when it's all done, compute
1806 the sum or product of each variable and adjust the original
1807 debug insn and each copy thereof. What a pain! */
1808 reset_debug_uses_in_loop (loop, dest, debug_uses);
1810 /* Record the accumulator to expand. */
1811 ves = XNEW (struct var_to_expand);
1813 ves->reg = copy_rtx (dest);
1814 ves->var_expansions.create (1);
1816 ves->op = GET_CODE (src);
1817 ves->expansion_count = 0;
1818 ves->reuse_expansion = 0;
1822 /* Determine whether there is an induction variable in INSN that
1823 we would like to split during unrolling.
1843 Return NULL if INSN contains no interesting IVs. Otherwise, allocate
1844 an IV_TO_SPLIT structure, fill it with the relevant information and return a
1847 static struct iv_to_split *
1848 analyze_iv_to_split_insn (rtx insn)
1852 struct iv_to_split *ivts;
1855 /* For now we just split the basic induction variables. Later this may be
1856 extended for example by selecting also addresses of memory references. */
1857 set = single_set (insn);
1861 dest = SET_DEST (set);
1865 if (!biv_p (insn, dest))
1868 ok = iv_analyze_result (insn, dest, &iv);
1870 /* This used to be an assert under the assumption that if biv_p returns
1871 true that iv_analyze_result must also return true. However, that
1872 assumption is not strictly correct as evidenced by pr25569.
1874 Returning NULL when iv_analyze_result returns false is safe and
1875 avoids the problems in pr25569 until the iv_analyze_* routines
1876 can be fixed, which is apparently hard and time consuming
1877 according to their author. */
1881 if (iv.step == const0_rtx
1882 || iv.mode != iv.extend_mode)
1885 /* Record the insn to split. */
1886 ivts = XNEW (struct iv_to_split);
1888 ivts->orig_var = dest;
1889 ivts->base_var = NULL_RTX;
1890 ivts->step = iv.step;
1898 /* Determines which of insns in LOOP can be optimized.
1899 Return a OPT_INFO struct with the relevant hash tables filled
1900 with all insns to be optimized. The FIRST_NEW_BLOCK field
1901 is undefined for the return value. */
1903 static struct opt_info *
1904 analyze_insns_in_loop (struct loop *loop)
1906 basic_block *body, bb;
1908 struct opt_info *opt_info = XCNEW (struct opt_info);
1910 struct iv_to_split *ivts = NULL;
1911 struct var_to_expand *ves = NULL;
1912 iv_to_split **slot1;
1913 var_to_expand **slot2;
1914 vec<edge> edges = get_loop_exit_edges (loop);
1916 bool can_apply = false;
1918 iv_analysis_loop_init (loop);
1920 body = get_loop_body (loop);
1922 if (flag_split_ivs_in_unroller)
1924 opt_info->insns_to_split.create (5 * loop->num_nodes);
1925 opt_info->iv_to_split_head = NULL;
1926 opt_info->iv_to_split_tail = &opt_info->iv_to_split_head;
1929 /* Record the loop exit bb and loop preheader before the unrolling. */
1930 opt_info->loop_preheader = loop_preheader_edge (loop)->src;
1932 if (edges.length () == 1)
1935 if (!(exit->flags & EDGE_COMPLEX))
1937 opt_info->loop_exit = split_edge (exit);
1942 if (flag_variable_expansion_in_unroller
1945 opt_info->insns_with_var_to_expand.create (5 * loop->num_nodes);
1946 opt_info->var_to_expand_head = NULL;
1947 opt_info->var_to_expand_tail = &opt_info->var_to_expand_head;
1950 for (i = 0; i < loop->num_nodes; i++)
1953 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
1956 FOR_BB_INSNS (bb, insn)
1961 if (opt_info->insns_to_split.is_created ())
1962 ivts = analyze_iv_to_split_insn (insn);
1966 slot1 = opt_info->insns_to_split.find_slot (ivts, INSERT);
1967 gcc_assert (*slot1 == NULL);
1969 *opt_info->iv_to_split_tail = ivts;
1970 opt_info->iv_to_split_tail = &ivts->next;
1974 if (opt_info->insns_with_var_to_expand.is_created ())
1975 ves = analyze_insn_to_expand_var (loop, insn);
1979 slot2 = opt_info->insns_with_var_to_expand.find_slot (ves, INSERT);
1980 gcc_assert (*slot2 == NULL);
1982 *opt_info->var_to_expand_tail = ves;
1983 opt_info->var_to_expand_tail = &ves->next;
1993 /* Called just before loop duplication. Records start of duplicated area
1997 opt_info_start_duplication (struct opt_info *opt_info)
2000 opt_info->first_new_block = last_basic_block_for_fn (cfun);
2003 /* Determine the number of iterations between initialization of the base
2004 variable and the current copy (N_COPY). N_COPIES is the total number
2005 of newly created copies. UNROLLING is true if we are unrolling
2006 (not peeling) the loop. */
2009 determine_split_iv_delta (unsigned n_copy, unsigned n_copies, bool unrolling)
2013 /* If we are unrolling, initialization is done in the original loop
2019 /* If we are peeling, the copy in that the initialization occurs has
2020 number 1. The original loop (number 0) is the last. */
2028 /* Locate in EXPR the expression corresponding to the location recorded
2029 in IVTS, and return a pointer to the RTX for this location. */
2032 get_ivts_expr (rtx expr, struct iv_to_split *ivts)
2037 for (i = 0; i < ivts->n_loc; i++)
2038 ret = &XEXP (*ret, ivts->loc[i]);
2043 /* Allocate basic variable for the induction variable chain. */
2046 allocate_basic_variable (struct iv_to_split *ivts)
2048 rtx expr = *get_ivts_expr (single_set (ivts->insn), ivts);
2050 ivts->base_var = gen_reg_rtx (GET_MODE (expr));
2053 /* Insert initialization of basic variable of IVTS before INSN, taking
2054 the initial value from INSN. */
2057 insert_base_initialization (struct iv_to_split *ivts, rtx insn)
2059 rtx expr = copy_rtx (*get_ivts_expr (single_set (insn), ivts));
2063 expr = force_operand (expr, ivts->base_var);
2064 if (expr != ivts->base_var)
2065 emit_move_insn (ivts->base_var, expr);
2069 emit_insn_before (seq, insn);
2072 /* Replace the use of induction variable described in IVTS in INSN
2073 by base variable + DELTA * step. */
2076 split_iv (struct iv_to_split *ivts, rtx insn, unsigned delta)
2078 rtx expr, *loc, seq, incr, var;
2079 enum machine_mode mode = GET_MODE (ivts->base_var);
2082 /* Construct base + DELTA * step. */
2084 expr = ivts->base_var;
2087 incr = simplify_gen_binary (MULT, mode,
2088 ivts->step, gen_int_mode (delta, mode));
2089 expr = simplify_gen_binary (PLUS, GET_MODE (ivts->base_var),
2090 ivts->base_var, incr);
2093 /* Figure out where to do the replacement. */
2094 loc = get_ivts_expr (single_set (insn), ivts);
2096 /* If we can make the replacement right away, we're done. */
2097 if (validate_change (insn, loc, expr, 0))
2100 /* Otherwise, force EXPR into a register and try again. */
2102 var = gen_reg_rtx (mode);
2103 expr = force_operand (expr, var);
2105 emit_move_insn (var, expr);
2108 emit_insn_before (seq, insn);
2110 if (validate_change (insn, loc, var, 0))
2113 /* The last chance. Try recreating the assignment in insn
2114 completely from scratch. */
2115 set = single_set (insn);
2120 src = copy_rtx (SET_SRC (set));
2121 dest = copy_rtx (SET_DEST (set));
2122 src = force_operand (src, dest);
2124 emit_move_insn (dest, src);
2128 emit_insn_before (seq, insn);
2133 /* Return one expansion of the accumulator recorded in struct VE. */
2136 get_expansion (struct var_to_expand *ve)
2140 if (ve->reuse_expansion == 0)
2143 reg = ve->var_expansions[ve->reuse_expansion - 1];
2145 if (ve->var_expansions.length () == (unsigned) ve->reuse_expansion)
2146 ve->reuse_expansion = 0;
2148 ve->reuse_expansion++;
2154 /* Given INSN replace the uses of the accumulator recorded in VE
2155 with a new register. */
2158 expand_var_during_unrolling (struct var_to_expand *ve, rtx insn)
2161 bool really_new_expansion = false;
2163 set = single_set (insn);
2166 /* Generate a new register only if the expansion limit has not been
2167 reached. Else reuse an already existing expansion. */
2168 if (PARAM_VALUE (PARAM_MAX_VARIABLE_EXPANSIONS) > ve->expansion_count)
2170 really_new_expansion = true;
2171 new_reg = gen_reg_rtx (GET_MODE (ve->reg));
2174 new_reg = get_expansion (ve);
2176 validate_replace_rtx_group (SET_DEST (set), new_reg, insn);
2177 if (apply_change_group ())
2178 if (really_new_expansion)
2180 ve->var_expansions.safe_push (new_reg);
2181 ve->expansion_count++;
2185 /* Initialize the variable expansions in loop preheader. PLACE is the
2186 loop-preheader basic block where the initialization of the
2187 expansions should take place. The expansions are initialized with
2188 (-0) when the operation is plus or minus to honor sign zero. This
2189 way we can prevent cases where the sign of the final result is
2190 effected by the sign of the expansion. Here is an example to
2193 for (i = 0 ; i < n; i++)
2207 When SUM is initialized with -zero and SOMETHING is also -zero; the
2208 final result of sum should be -zero thus the expansions sum1 and sum2
2209 should be initialized with -zero as well (otherwise we will get +zero
2210 as the final result). */
2213 insert_var_expansion_initialization (struct var_to_expand *ve,
2216 rtx seq, var, zero_init;
2218 enum machine_mode mode = GET_MODE (ve->reg);
2219 bool honor_signed_zero_p = HONOR_SIGNED_ZEROS (mode);
2221 if (ve->var_expansions.length () == 0)
2228 /* Note that we only accumulate FMA via the ADD operand. */
2231 FOR_EACH_VEC_ELT (ve->var_expansions, i, var)
2233 if (honor_signed_zero_p)
2234 zero_init = simplify_gen_unary (NEG, mode, CONST0_RTX (mode), mode);
2236 zero_init = CONST0_RTX (mode);
2237 emit_move_insn (var, zero_init);
2242 FOR_EACH_VEC_ELT (ve->var_expansions, i, var)
2244 zero_init = CONST1_RTX (GET_MODE (var));
2245 emit_move_insn (var, zero_init);
2256 emit_insn_after (seq, BB_END (place));
2259 /* Combine the variable expansions at the loop exit. PLACE is the
2260 loop exit basic block where the summation of the expansions should
2264 combine_var_copies_in_loop_exit (struct var_to_expand *ve, basic_block place)
2267 rtx expr, seq, var, insn;
2270 if (ve->var_expansions.length () == 0)
2277 /* Note that we only accumulate FMA via the ADD operand. */
2280 FOR_EACH_VEC_ELT (ve->var_expansions, i, var)
2281 sum = simplify_gen_binary (PLUS, GET_MODE (ve->reg), var, sum);
2285 FOR_EACH_VEC_ELT (ve->var_expansions, i, var)
2286 sum = simplify_gen_binary (MULT, GET_MODE (ve->reg), var, sum);
2293 expr = force_operand (sum, ve->reg);
2294 if (expr != ve->reg)
2295 emit_move_insn (ve->reg, expr);
2299 insn = BB_HEAD (place);
2300 while (!NOTE_INSN_BASIC_BLOCK_P (insn))
2301 insn = NEXT_INSN (insn);
2303 emit_insn_after (seq, insn);
2306 /* Strip away REG_EQUAL notes for IVs we're splitting.
2308 Updating REG_EQUAL notes for IVs we split is tricky: We
2309 cannot tell until after unrolling, DF-rescanning, and liveness
2310 updating, whether an EQ_USE is reached by the split IV while
2311 the IV reg is still live. See PR55006.
2313 ??? We cannot use remove_reg_equal_equiv_notes_for_regno,
2314 because RTL loop-iv requires us to defer rescanning insns and
2315 any notes attached to them. So resort to old techniques... */
2318 maybe_strip_eq_note_for_split_iv (struct opt_info *opt_info, rtx insn)
2320 struct iv_to_split *ivts;
2321 rtx note = find_reg_equal_equiv_note (insn);
2324 for (ivts = opt_info->iv_to_split_head; ivts; ivts = ivts->next)
2325 if (reg_mentioned_p (ivts->orig_var, note))
2327 remove_note (insn, note);
2332 /* Apply loop optimizations in loop copies using the
2333 data which gathered during the unrolling. Structure
2334 OPT_INFO record that data.
2336 UNROLLING is true if we unrolled (not peeled) the loop.
2337 REWRITE_ORIGINAL_BODY is true if we should also rewrite the original body of
2338 the loop (as it should happen in complete unrolling, but not in ordinary
2339 peeling of the loop). */
2342 apply_opt_in_copies (struct opt_info *opt_info,
2343 unsigned n_copies, bool unrolling,
2344 bool rewrite_original_loop)
2347 basic_block bb, orig_bb;
2348 rtx insn, orig_insn, next;
2349 struct iv_to_split ivts_templ, *ivts;
2350 struct var_to_expand ve_templ, *ves;
2352 /* Sanity check -- we need to put initialization in the original loop
2354 gcc_assert (!unrolling || rewrite_original_loop);
2356 /* Allocate the basic variables (i0). */
2357 if (opt_info->insns_to_split.is_created ())
2358 for (ivts = opt_info->iv_to_split_head; ivts; ivts = ivts->next)
2359 allocate_basic_variable (ivts);
2361 for (i = opt_info->first_new_block;
2362 i < (unsigned) last_basic_block_for_fn (cfun);
2365 bb = BASIC_BLOCK_FOR_FN (cfun, i);
2366 orig_bb = get_bb_original (bb);
2368 /* bb->aux holds position in copy sequence initialized by
2369 duplicate_loop_to_header_edge. */
2370 delta = determine_split_iv_delta ((size_t)bb->aux, n_copies,
2373 orig_insn = BB_HEAD (orig_bb);
2374 FOR_BB_INSNS_SAFE (bb, insn, next)
2377 || (DEBUG_INSN_P (insn)
2378 && TREE_CODE (INSN_VAR_LOCATION_DECL (insn)) == LABEL_DECL))
2381 while (!INSN_P (orig_insn)
2382 || (DEBUG_INSN_P (orig_insn)
2383 && (TREE_CODE (INSN_VAR_LOCATION_DECL (orig_insn))
2385 orig_insn = NEXT_INSN (orig_insn);
2387 ivts_templ.insn = orig_insn;
2388 ve_templ.insn = orig_insn;
2390 /* Apply splitting iv optimization. */
2391 if (opt_info->insns_to_split.is_created ())
2393 maybe_strip_eq_note_for_split_iv (opt_info, insn);
2395 ivts = opt_info->insns_to_split.find (&ivts_templ);
2399 gcc_assert (GET_CODE (PATTERN (insn))
2400 == GET_CODE (PATTERN (orig_insn)));
2403 insert_base_initialization (ivts, insn);
2404 split_iv (ivts, insn, delta);
2407 /* Apply variable expansion optimization. */
2408 if (unrolling && opt_info->insns_with_var_to_expand.is_created ())
2410 ves = (struct var_to_expand *)
2411 opt_info->insns_with_var_to_expand.find (&ve_templ);
2414 gcc_assert (GET_CODE (PATTERN (insn))
2415 == GET_CODE (PATTERN (orig_insn)));
2416 expand_var_during_unrolling (ves, insn);
2419 orig_insn = NEXT_INSN (orig_insn);
2423 if (!rewrite_original_loop)
2426 /* Initialize the variable expansions in the loop preheader
2427 and take care of combining them at the loop exit. */
2428 if (opt_info->insns_with_var_to_expand.is_created ())
2430 for (ves = opt_info->var_to_expand_head; ves; ves = ves->next)
2431 insert_var_expansion_initialization (ves, opt_info->loop_preheader);
2432 for (ves = opt_info->var_to_expand_head; ves; ves = ves->next)
2433 combine_var_copies_in_loop_exit (ves, opt_info->loop_exit);
2436 /* Rewrite also the original loop body. Find them as originals of the blocks
2437 in the last copied iteration, i.e. those that have
2438 get_bb_copy (get_bb_original (bb)) == bb. */
2439 for (i = opt_info->first_new_block;
2440 i < (unsigned) last_basic_block_for_fn (cfun);
2443 bb = BASIC_BLOCK_FOR_FN (cfun, i);
2444 orig_bb = get_bb_original (bb);
2445 if (get_bb_copy (orig_bb) != bb)
2448 delta = determine_split_iv_delta (0, n_copies, unrolling);
2449 for (orig_insn = BB_HEAD (orig_bb);
2450 orig_insn != NEXT_INSN (BB_END (bb));
2453 next = NEXT_INSN (orig_insn);
2455 if (!INSN_P (orig_insn))
2458 ivts_templ.insn = orig_insn;
2459 if (opt_info->insns_to_split.is_created ())
2461 maybe_strip_eq_note_for_split_iv (opt_info, orig_insn);
2463 ivts = (struct iv_to_split *)
2464 opt_info->insns_to_split.find (&ivts_templ);
2468 insert_base_initialization (ivts, orig_insn);
2469 split_iv (ivts, orig_insn, delta);
2478 /* Release OPT_INFO. */
2481 free_opt_info (struct opt_info *opt_info)
2483 if (opt_info->insns_to_split.is_created ())
2484 opt_info->insns_to_split.dispose ();
2485 if (opt_info->insns_with_var_to_expand.is_created ())
2487 struct var_to_expand *ves;
2489 for (ves = opt_info->var_to_expand_head; ves; ves = ves->next)
2490 ves->var_expansions.release ();
2491 opt_info->insns_with_var_to_expand.dispose ();