1 /* Perform various loop optimizations, including strength reduction.
2 Copyright (C) 1987, 88, 89, 91-97, 1998 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This is the loop optimization pass of the compiler.
23 It finds invariant computations within loops and moves them
24 to the beginning of the loop. Then it identifies basic and
25 general induction variables. Strength reduction is applied to the general
26 induction variables, and induction variable elimination is applied to
27 the basic induction variables.
29 It also finds cases where
30 a register is set within the loop by zero-extending a narrower value
31 and changes these to zero the entire register once before the loop
32 and merely copy the low part within the loop.
34 Most of the complexity is in heuristics to decide when it is worth
35 while to do these things. */
42 #include "insn-config.h"
43 #include "insn-flags.h"
45 #include "hard-reg-set.h"
53 /* Vector mapping INSN_UIDs to luids.
54 The luids are like uids but increase monotonically always.
55 We use them to see whether a jump comes from outside a given loop. */
59 /* Indexed by INSN_UID, contains the ordinal giving the (innermost) loop
60 number the insn is contained in. */
64 /* 1 + largest uid of any insn. */
68 /* 1 + luid of last insn. */
72 /* Number of loops detected in current function. Used as index to the
75 static int max_loop_num;
77 /* Indexed by loop number, contains the first and last insn of each loop. */
79 static rtx *loop_number_loop_starts, *loop_number_loop_ends;
81 /* For each loop, gives the containing loop number, -1 if none. */
85 #ifdef HAVE_decrement_and_branch_on_count
86 /* Records whether resource in use by inner loop. */
88 int *loop_used_count_register;
89 #endif /* HAVE_decrement_and_branch_on_count */
91 /* For each loop, keep track of its unrolling factor.
95 -1: completely unrolled
96 >0: holds the unroll exact factor. */
97 int *loop_unroll_factor;
99 /* Indexed by loop number, contains a nonzero value if the "loop" isn't
100 really a loop (an insn outside the loop branches into it). */
102 static char *loop_invalid;
104 /* Indexed by loop number, links together all LABEL_REFs which refer to
105 code labels outside the loop. Used by routines that need to know all
106 loop exits, such as final_biv_value and final_giv_value.
108 This does not include loop exits due to return instructions. This is
109 because all bivs and givs are pseudos, and hence must be dead after a
110 return, so the presense of a return does not affect any of the
111 optimizations that use this info. It is simpler to just not include return
112 instructions on this list. */
114 rtx *loop_number_exit_labels;
116 /* Indexed by loop number, counts the number of LABEL_REFs on
117 loop_number_exit_labels for this loop and all loops nested inside it. */
119 int *loop_number_exit_count;
121 /* Holds the number of loop iterations. It is zero if the number could not be
122 calculated. Must be unsigned since the number of iterations can
123 be as high as 2^wordsize-1. For loops with a wider iterator, this number
124 will be zero if the number of loop iterations is too large for an
125 unsigned integer to hold. */
127 unsigned HOST_WIDE_INT loop_n_iterations;
129 /* Nonzero if there is a subroutine call in the current loop. */
131 static int loop_has_call;
133 /* Nonzero if there is a volatile memory reference in the current
136 static int loop_has_volatile;
138 /* Added loop_continue which is the NOTE_INSN_LOOP_CONT of the
139 current loop. A continue statement will generate a branch to
140 NEXT_INSN (loop_continue). */
142 static rtx loop_continue;
144 /* Indexed by register number, contains the number of times the reg
145 is set during the loop being scanned.
146 During code motion, a negative value indicates a reg that has been
147 made a candidate; in particular -2 means that it is an candidate that
148 we know is equal to a constant and -1 means that it is an candidate
149 not known equal to a constant.
150 After code motion, regs moved have 0 (which is accurate now)
151 while the failed candidates have the original number of times set.
153 Therefore, at all times, == 0 indicates an invariant register;
154 < 0 a conditionally invariant one. */
156 static varray_type n_times_set;
158 /* Original value of n_times_set; same except that this value
159 is not set negative for a reg whose sets have been made candidates
160 and not set to 0 for a reg that is moved. */
162 static varray_type n_times_used;
164 /* Index by register number, 1 indicates that the register
165 cannot be moved or strength reduced. */
167 static varray_type may_not_optimize;
169 /* Nonzero means reg N has already been moved out of one loop.
170 This reduces the desire to move it out of another. */
172 static char *moved_once;
174 /* Array of MEMs that are stored in this loop. If there are too many to fit
175 here, we just turn on unknown_address_altered. */
177 #define NUM_STORES 30
178 static rtx loop_store_mems[NUM_STORES];
180 /* Index of first available slot in above array. */
181 static int loop_store_mems_idx;
183 typedef struct loop_mem_info {
184 rtx mem; /* The MEM itself. */
185 rtx reg; /* Corresponding pseudo, if any. */
186 int optimize; /* Nonzero if we can optimize access to this MEM. */
189 /* Array of MEMs that are used (read or written) in this loop, but
190 cannot be aliased by anything in this loop, except perhaps
191 themselves. In other words, if loop_mems[i] is altered during the
192 loop, it is altered by an expression that is rtx_equal_p to it. */
194 static loop_mem_info *loop_mems;
196 /* The index of the next available slot in LOOP_MEMS. */
198 static int loop_mems_idx;
200 /* The number of elements allocated in LOOP_MEMs. */
202 static int loop_mems_allocated;
204 /* Nonzero if we don't know what MEMs were changed in the current loop.
205 This happens if the loop contains a call (in which case `loop_has_call'
206 will also be set) or if we store into more than NUM_STORES MEMs. */
208 static int unknown_address_altered;
210 /* Count of movable (i.e. invariant) instructions discovered in the loop. */
211 static int num_movables;
213 /* Count of memory write instructions discovered in the loop. */
214 static int num_mem_sets;
216 /* Number of loops contained within the current one, including itself. */
217 static int loops_enclosed;
219 /* Bound on pseudo register number before loop optimization.
220 A pseudo has valid regscan info if its number is < max_reg_before_loop. */
221 int max_reg_before_loop;
223 /* This obstack is used in product_cheap_p to allocate its rtl. It
224 may call gen_reg_rtx which, in turn, may reallocate regno_reg_rtx.
225 If we used the same obstack that it did, we would be deallocating
228 static struct obstack temp_obstack;
230 /* This is where the pointer to the obstack being used for RTL is stored. */
232 extern struct obstack *rtl_obstack;
234 #define obstack_chunk_alloc xmalloc
235 #define obstack_chunk_free free
237 /* During the analysis of a loop, a chain of `struct movable's
238 is made to record all the movable insns found.
239 Then the entire chain can be scanned to decide which to move. */
243 rtx insn; /* A movable insn */
244 rtx set_src; /* The expression this reg is set from. */
245 rtx set_dest; /* The destination of this SET. */
246 rtx dependencies; /* When INSN is libcall, this is an EXPR_LIST
247 of any registers used within the LIBCALL. */
248 int consec; /* Number of consecutive following insns
249 that must be moved with this one. */
250 int regno; /* The register it sets */
251 short lifetime; /* lifetime of that register;
252 may be adjusted when matching movables
253 that load the same value are found. */
254 short savings; /* Number of insns we can move for this reg,
255 including other movables that force this
256 or match this one. */
257 unsigned int cond : 1; /* 1 if only conditionally movable */
258 unsigned int force : 1; /* 1 means MUST move this insn */
259 unsigned int global : 1; /* 1 means reg is live outside this loop */
260 /* If PARTIAL is 1, GLOBAL means something different:
261 that the reg is live outside the range from where it is set
262 to the following label. */
263 unsigned int done : 1; /* 1 inhibits further processing of this */
265 unsigned int partial : 1; /* 1 means this reg is used for zero-extending.
266 In particular, moving it does not make it
268 unsigned int move_insn : 1; /* 1 means that we call emit_move_insn to
269 load SRC, rather than copying INSN. */
270 unsigned int move_insn_first:1;/* Same as above, if this is necessary for the
271 first insn of a consecutive sets group. */
272 unsigned int is_equiv : 1; /* 1 means a REG_EQUIV is present on INSN. */
273 enum machine_mode savemode; /* Nonzero means it is a mode for a low part
274 that we should avoid changing when clearing
275 the rest of the reg. */
276 struct movable *match; /* First entry for same value */
277 struct movable *forces; /* An insn that must be moved if this is */
278 struct movable *next;
281 static struct movable *the_movables;
283 FILE *loop_dump_stream;
285 /* Forward declarations. */
287 static void find_and_verify_loops PROTO((rtx));
288 static void mark_loop_jump PROTO((rtx, int));
289 static void prescan_loop PROTO((rtx, rtx));
290 static int reg_in_basic_block_p PROTO((rtx, rtx));
291 static int consec_sets_invariant_p PROTO((rtx, int, rtx));
292 static rtx libcall_other_reg PROTO((rtx, rtx));
293 static int labels_in_range_p PROTO((rtx, int));
294 static void count_one_set PROTO((rtx, rtx, varray_type, rtx *));
296 static void count_loop_regs_set PROTO((rtx, rtx, varray_type, varray_type,
298 static void note_addr_stored PROTO((rtx, rtx));
299 static int loop_reg_used_before_p PROTO((rtx, rtx, rtx, rtx, rtx));
300 static void scan_loop PROTO((rtx, rtx, int, int));
302 static void replace_call_address PROTO((rtx, rtx, rtx));
304 static rtx skip_consec_insns PROTO((rtx, int));
305 static int libcall_benefit PROTO((rtx));
306 static void ignore_some_movables PROTO((struct movable *));
307 static void force_movables PROTO((struct movable *));
308 static void combine_movables PROTO((struct movable *, int));
309 static int regs_match_p PROTO((rtx, rtx, struct movable *));
310 static int rtx_equal_for_loop_p PROTO((rtx, rtx, struct movable *));
311 static void add_label_notes PROTO((rtx, rtx));
312 static void move_movables PROTO((struct movable *, int, int, rtx, rtx, int));
313 static int count_nonfixed_reads PROTO((rtx));
314 static void strength_reduce PROTO((rtx, rtx, rtx, int, rtx, rtx, int, int));
315 static void find_single_use_in_loop PROTO((rtx, rtx, varray_type));
316 static int valid_initial_value_p PROTO((rtx, rtx, int, rtx));
317 static void find_mem_givs PROTO((rtx, rtx, int, rtx, rtx));
318 static void record_biv PROTO((struct induction *, rtx, rtx, rtx, rtx, int, int));
319 static void check_final_value PROTO((struct induction *, rtx, rtx));
320 static void record_giv PROTO((struct induction *, rtx, rtx, rtx, rtx, rtx, int, enum g_types, int, rtx *, rtx, rtx));
321 static void update_giv_derive PROTO((rtx));
322 static int basic_induction_var PROTO((rtx, enum machine_mode, rtx, rtx, rtx *, rtx *));
323 static rtx simplify_giv_expr PROTO((rtx, int *));
324 static int general_induction_var PROTO((rtx, rtx *, rtx *, rtx *, int, int *));
325 static int consec_sets_giv PROTO((int, rtx, rtx, rtx, rtx *, rtx *));
326 static int check_dbra_loop PROTO((rtx, int, rtx));
327 static rtx express_from_1 PROTO((rtx, rtx, rtx));
328 static rtx express_from PROTO((struct induction *, struct induction *));
329 static rtx combine_givs_p PROTO((struct induction *, struct induction *));
330 static void combine_givs PROTO((struct iv_class *));
331 static int product_cheap_p PROTO((rtx, rtx));
332 static int maybe_eliminate_biv PROTO((struct iv_class *, rtx, rtx, int, int, int));
333 static int maybe_eliminate_biv_1 PROTO((rtx, rtx, struct iv_class *, int, rtx));
334 static int last_use_this_basic_block PROTO((rtx, rtx));
335 static void record_initial PROTO((rtx, rtx));
336 static void update_reg_last_use PROTO((rtx, rtx));
337 static rtx next_insn_in_loop PROTO((rtx, rtx, rtx, rtx));
338 static void load_mems_and_recount_loop_regs_set PROTO((rtx, rtx, rtx,
341 static void load_mems PROTO((rtx, rtx, rtx, rtx));
342 static int insert_loop_mem PROTO((rtx *, void *));
343 static int replace_loop_mem PROTO((rtx *, void *));
344 static int replace_label PROTO((rtx *, void *));
346 typedef struct rtx_and_int {
351 typedef struct rtx_pair {
356 /* Nonzero iff INSN is between START and END, inclusive. */
357 #define INSN_IN_RANGE_P(INSN, START, END) \
358 (INSN_UID (INSN) < max_uid_for_loop \
359 && INSN_LUID (INSN) >= INSN_LUID (START) \
360 && INSN_LUID (INSN) <= INSN_LUID (END))
362 #ifdef HAVE_decrement_and_branch_on_count
363 /* Test whether BCT applicable and safe. */
364 static void insert_bct PROTO((rtx, rtx));
366 /* Auxiliary function that inserts the BCT pattern into the loop. */
367 static void instrument_loop_bct PROTO((rtx, rtx, rtx));
368 #endif /* HAVE_decrement_and_branch_on_count */
370 /* Indirect_jump_in_function is computed once per function. */
371 int indirect_jump_in_function = 0;
372 static int indirect_jump_in_function_p PROTO((rtx));
375 /* Relative gain of eliminating various kinds of operations. */
378 static int shift_cost;
379 static int mult_cost;
382 /* Benefit penalty, if a giv is not replaceable, i.e. must emit an insn to
383 copy the value of the strength reduced giv to its original register. */
384 static int copy_cost;
386 /* Cost of using a register, to normalize the benefits of a giv. */
387 static int reg_address_cost;
393 char *free_point = (char *) oballoc (1);
394 rtx reg = gen_rtx_REG (word_mode, LAST_VIRTUAL_REGISTER + 1);
396 add_cost = rtx_cost (gen_rtx_PLUS (word_mode, reg, reg), SET);
399 reg_address_cost = ADDRESS_COST (reg);
401 reg_address_cost = rtx_cost (reg, MEM);
404 /* We multiply by 2 to reconcile the difference in scale between
405 these two ways of computing costs. Otherwise the cost of a copy
406 will be far less than the cost of an add. */
410 /* Free the objects we just allocated. */
413 /* Initialize the obstack used for rtl in product_cheap_p. */
414 gcc_obstack_init (&temp_obstack);
417 /* Entry point of this file. Perform loop optimization
418 on the current function. F is the first insn of the function
419 and DUMPFILE is a stream for output of a trace of actions taken
420 (or 0 if none should be output). */
423 loop_optimize (f, dumpfile, unroll_p, bct_p)
424 /* f is the first instruction of a chain of insns for one function */
433 loop_dump_stream = dumpfile;
435 init_recog_no_volatile ();
437 max_reg_before_loop = max_reg_num ();
439 moved_once = (char *) alloca (max_reg_before_loop);
440 bzero (moved_once, max_reg_before_loop);
444 /* Count the number of loops. */
447 for (insn = f; insn; insn = NEXT_INSN (insn))
449 if (GET_CODE (insn) == NOTE
450 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
454 /* Don't waste time if no loops. */
455 if (max_loop_num == 0)
458 /* Get size to use for tables indexed by uids.
459 Leave some space for labels allocated by find_and_verify_loops. */
460 max_uid_for_loop = get_max_uid () + 1 + max_loop_num * 32;
462 uid_luid = (int *) alloca (max_uid_for_loop * sizeof (int));
463 uid_loop_num = (int *) alloca (max_uid_for_loop * sizeof (int));
465 bzero ((char *) uid_luid, max_uid_for_loop * sizeof (int));
466 bzero ((char *) uid_loop_num, max_uid_for_loop * sizeof (int));
468 /* Allocate tables for recording each loop. We set each entry, so they need
470 loop_number_loop_starts = (rtx *) alloca (max_loop_num * sizeof (rtx));
471 loop_number_loop_ends = (rtx *) alloca (max_loop_num * sizeof (rtx));
472 loop_outer_loop = (int *) alloca (max_loop_num * sizeof (int));
473 loop_invalid = (char *) alloca (max_loop_num * sizeof (char));
474 loop_number_exit_labels = (rtx *) alloca (max_loop_num * sizeof (rtx));
475 loop_number_exit_count = (int *) alloca (max_loop_num * sizeof (int));
477 /* This is initialized by the unrolling code, so we go ahead
478 and clear them just in case we are not performing loop
480 loop_unroll_factor = (int *) alloca (max_loop_num *sizeof (int));
481 bzero ((char *) loop_unroll_factor, max_loop_num * sizeof (int));
483 #ifdef HAVE_decrement_and_branch_on_count
484 /* Allocate for BCT optimization */
485 loop_used_count_register = (int *) alloca (max_loop_num * sizeof (int));
486 bzero ((char *) loop_used_count_register, max_loop_num * sizeof (int));
487 #endif /* HAVE_decrement_and_branch_on_count */
489 /* Find and process each loop.
490 First, find them, and record them in order of their beginnings. */
491 find_and_verify_loops (f);
493 /* Now find all register lifetimes. This must be done after
494 find_and_verify_loops, because it might reorder the insns in the
496 reg_scan (f, max_reg_num (), 1);
498 /* This must occur after reg_scan so that registers created by gcse
499 will have entries in the register tables.
501 We could have added a call to reg_scan after gcse_main in toplev.c,
502 but moving this call to init_alias_analysis is more efficient. */
503 init_alias_analysis ();
505 /* See if we went too far. */
506 if (get_max_uid () > max_uid_for_loop)
508 /* Now reset it to the actual size we need. See above. */
509 max_uid_for_loop = get_max_uid () + 1;
511 /* Compute the mapping from uids to luids.
512 LUIDs are numbers assigned to insns, like uids,
513 except that luids increase monotonically through the code.
514 Don't assign luids to line-number NOTEs, so that the distance in luids
515 between two insns is not affected by -g. */
517 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
520 if (GET_CODE (insn) != NOTE
521 || NOTE_LINE_NUMBER (insn) <= 0)
522 uid_luid[INSN_UID (insn)] = ++i;
524 /* Give a line number note the same luid as preceding insn. */
525 uid_luid[INSN_UID (insn)] = i;
530 /* Don't leave gaps in uid_luid for insns that have been
531 deleted. It is possible that the first or last insn
532 using some register has been deleted by cross-jumping.
533 Make sure that uid_luid for that former insn's uid
534 points to the general area where that insn used to be. */
535 for (i = 0; i < max_uid_for_loop; i++)
537 uid_luid[0] = uid_luid[i];
538 if (uid_luid[0] != 0)
541 for (i = 0; i < max_uid_for_loop; i++)
542 if (uid_luid[i] == 0)
543 uid_luid[i] = uid_luid[i - 1];
545 /* Create a mapping from loops to BLOCK tree nodes. */
546 if (unroll_p && write_symbols != NO_DEBUG)
547 find_loop_tree_blocks ();
549 /* Determine if the function has indirect jump. On some systems
550 this prevents low overhead loop instructions from being used. */
551 indirect_jump_in_function = indirect_jump_in_function_p (f);
553 /* Now scan the loops, last ones first, since this means inner ones are done
554 before outer ones. */
555 for (i = max_loop_num-1; i >= 0; i--)
556 if (! loop_invalid[i] && loop_number_loop_ends[i])
557 scan_loop (loop_number_loop_starts[i], loop_number_loop_ends[i],
560 /* If debugging and unrolling loops, we must replicate the tree nodes
561 corresponding to the blocks inside the loop, so that the original one
562 to one mapping will remain. */
563 if (unroll_p && write_symbols != NO_DEBUG)
564 unroll_block_trees ();
566 end_alias_analysis ();
569 /* Returns the next insn, in execution order, after INSN. START and
570 END are the NOTE_INSN_LOOP_BEG and NOTE_INSN_LOOP_END for the loop,
571 respectively. LOOP_TOP, if non-NULL, is the top of the loop in the
572 insn-stream; it is used with loops that are entered near the
576 next_insn_in_loop (insn, start, end, loop_top)
582 insn = NEXT_INSN (insn);
587 /* Go to the top of the loop, and continue there. */
601 /* Optimize one loop whose start is LOOP_START and end is END.
602 LOOP_START is the NOTE_INSN_LOOP_BEG and END is the matching
603 NOTE_INSN_LOOP_END. */
605 /* ??? Could also move memory writes out of loops if the destination address
606 is invariant, the source is invariant, the memory write is not volatile,
607 and if we can prove that no read inside the loop can read this address
608 before the write occurs. If there is a read of this address after the
609 write, then we can also mark the memory read as invariant. */
612 scan_loop (loop_start, end, unroll_p, bct_p)
618 /* 1 if we are scanning insns that could be executed zero times. */
620 /* 1 if we are scanning insns that might never be executed
621 due to a subroutine call which might exit before they are reached. */
623 /* For a rotated loop that is entered near the bottom,
624 this is the label at the top. Otherwise it is zero. */
626 /* Jump insn that enters the loop, or 0 if control drops in. */
627 rtx loop_entry_jump = 0;
628 /* Place in the loop where control enters. */
630 /* Number of insns in the loop. */
635 /* The SET from an insn, if it is the only SET in the insn. */
637 /* Chain describing insns movable in current loop. */
638 struct movable *movables = 0;
639 /* Last element in `movables' -- so we can add elements at the end. */
640 struct movable *last_movable = 0;
641 /* Ratio of extra register life span we can justify
642 for saving an instruction. More if loop doesn't call subroutines
643 since in that case saving an insn makes more difference
644 and more registers are available. */
646 /* If we have calls, contains the insn in which a register was used
647 if it was used exactly once; contains const0_rtx if it was used more
649 varray_type reg_single_usage = 0;
650 /* Nonzero if we are scanning instructions in a sub-loop. */
654 /* Determine whether this loop starts with a jump down to a test at
655 the end. This will occur for a small number of loops with a test
656 that is too complex to duplicate in front of the loop.
658 We search for the first insn or label in the loop, skipping NOTEs.
659 However, we must be careful not to skip past a NOTE_INSN_LOOP_BEG
660 (because we might have a loop executed only once that contains a
661 loop which starts with a jump to its exit test) or a NOTE_INSN_LOOP_END
662 (in case we have a degenerate loop).
664 Note that if we mistakenly think that a loop is entered at the top
665 when, in fact, it is entered at the exit test, the only effect will be
666 slightly poorer optimization. Making the opposite error can generate
667 incorrect code. Since very few loops now start with a jump to the
668 exit test, the code here to detect that case is very conservative. */
670 for (p = NEXT_INSN (loop_start);
672 && GET_CODE (p) != CODE_LABEL && GET_RTX_CLASS (GET_CODE (p)) != 'i'
673 && (GET_CODE (p) != NOTE
674 || (NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_BEG
675 && NOTE_LINE_NUMBER (p) != NOTE_INSN_LOOP_END));
681 /* Set up variables describing this loop. */
682 prescan_loop (loop_start, end);
683 threshold = (loop_has_call ? 1 : 2) * (1 + n_non_fixed_regs);
685 /* If loop has a jump before the first label,
686 the true entry is the target of that jump.
687 Start scan from there.
688 But record in LOOP_TOP the place where the end-test jumps
689 back to so we can scan that after the end of the loop. */
690 if (GET_CODE (p) == JUMP_INSN)
694 /* Loop entry must be unconditional jump (and not a RETURN) */
696 && JUMP_LABEL (p) != 0
697 /* Check to see whether the jump actually
698 jumps out of the loop (meaning it's no loop).
699 This case can happen for things like
700 do {..} while (0). If this label was generated previously
701 by loop, we can't tell anything about it and have to reject
703 && INSN_IN_RANGE_P (JUMP_LABEL (p), loop_start, end))
705 loop_top = next_label (scan_start);
706 scan_start = JUMP_LABEL (p);
710 /* If SCAN_START was an insn created by loop, we don't know its luid
711 as required by loop_reg_used_before_p. So skip such loops. (This
712 test may never be true, but it's best to play it safe.)
714 Also, skip loops where we do not start scanning at a label. This
715 test also rejects loops starting with a JUMP_INSN that failed the
718 if (INSN_UID (scan_start) >= max_uid_for_loop
719 || GET_CODE (scan_start) != CODE_LABEL)
721 if (loop_dump_stream)
722 fprintf (loop_dump_stream, "\nLoop from %d to %d is phony.\n\n",
723 INSN_UID (loop_start), INSN_UID (end));
727 /* Count number of times each reg is set during this loop.
728 Set VARRAY_CHAR (may_not_optimize, I) if it is not safe to move out
729 the setting of register I. If this loop has calls, set
730 VARRAY_RTX (reg_single_usage, I). */
732 /* Allocate extra space for REGS that might be created by
733 load_mems. We allocate a little extra slop as well, in the hopes
734 that even after the moving of movables creates some new registers
735 we won't have to reallocate these arrays. However, we do grow
736 the arrays, if necessary, in load_mems_recount_loop_regs_set. */
737 nregs = max_reg_num () + loop_mems_idx + 16;
738 VARRAY_INT_INIT (n_times_set, nregs, "n_times_set");
739 VARRAY_INT_INIT (n_times_used, nregs, "n_times_used");
740 VARRAY_CHAR_INIT (may_not_optimize, nregs, "may_not_optimize");
743 VARRAY_RTX_INIT (reg_single_usage, nregs, "reg_single_usage");
745 count_loop_regs_set (loop_top ? loop_top : loop_start, end,
746 may_not_optimize, reg_single_usage, &insn_count, nregs);
748 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
750 VARRAY_CHAR (may_not_optimize, i) = 1;
751 VARRAY_INT (n_times_set, i) = 1;
754 #ifdef AVOID_CCMODE_COPIES
755 /* Don't try to move insns which set CC registers if we should not
756 create CCmode register copies. */
757 for (i = max_reg_num () - 1; i >= FIRST_PSEUDO_REGISTER; i--)
758 if (GET_MODE_CLASS (GET_MODE (regno_reg_rtx[i])) == MODE_CC)
759 VARRAY_CHAR (may_not_optimize, i) = 1;
762 bcopy ((char *) &n_times_set->data,
763 (char *) &n_times_used->data, nregs * sizeof (int));
765 if (loop_dump_stream)
767 fprintf (loop_dump_stream, "\nLoop from %d to %d: %d real insns.\n",
768 INSN_UID (loop_start), INSN_UID (end), insn_count);
770 fprintf (loop_dump_stream, "Continue at insn %d.\n",
771 INSN_UID (loop_continue));
774 /* Scan through the loop finding insns that are safe to move.
775 Set n_times_set negative for the reg being set, so that
776 this reg will be considered invariant for subsequent insns.
777 We consider whether subsequent insns use the reg
778 in deciding whether it is worth actually moving.
780 MAYBE_NEVER is nonzero if we have passed a conditional jump insn
781 and therefore it is possible that the insns we are scanning
782 would never be executed. At such times, we must make sure
783 that it is safe to execute the insn once instead of zero times.
784 When MAYBE_NEVER is 0, all insns will be executed at least once
785 so that is not a problem. */
787 for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
789 p = next_insn_in_loop (p, scan_start, end, loop_top))
791 if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
792 && find_reg_note (p, REG_LIBCALL, NULL_RTX))
794 else if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
795 && find_reg_note (p, REG_RETVAL, NULL_RTX))
798 if (GET_CODE (p) == INSN
799 && (set = single_set (p))
800 && GET_CODE (SET_DEST (set)) == REG
801 && ! VARRAY_CHAR (may_not_optimize, REGNO (SET_DEST (set))))
806 rtx src = SET_SRC (set);
807 rtx dependencies = 0;
809 /* Figure out what to use as a source of this insn. If a REG_EQUIV
810 note is given or if a REG_EQUAL note with a constant operand is
811 specified, use it as the source and mark that we should move
812 this insn by calling emit_move_insn rather that duplicating the
815 Otherwise, only use the REG_EQUAL contents if a REG_RETVAL note
817 temp = find_reg_note (p, REG_EQUIV, NULL_RTX);
819 src = XEXP (temp, 0), move_insn = 1;
822 temp = find_reg_note (p, REG_EQUAL, NULL_RTX);
823 if (temp && CONSTANT_P (XEXP (temp, 0)))
824 src = XEXP (temp, 0), move_insn = 1;
825 if (temp && find_reg_note (p, REG_RETVAL, NULL_RTX))
827 src = XEXP (temp, 0);
828 /* A libcall block can use regs that don't appear in
829 the equivalent expression. To move the libcall,
830 we must move those regs too. */
831 dependencies = libcall_other_reg (p, src);
835 /* Don't try to optimize a register that was made
836 by loop-optimization for an inner loop.
837 We don't know its life-span, so we can't compute the benefit. */
838 if (REGNO (SET_DEST (set)) >= max_reg_before_loop)
840 else if (/* The set is a user-variable or it is used in
841 the exit test (this can cause the variable to be
842 used before it is set just like a
844 (REG_USERVAR_P (SET_DEST (set))
845 || REG_LOOP_TEST_P (SET_DEST (set)))
846 /* And the set is not guaranteed to be executed one
847 the loop starts, or the value before the set is
848 needed before the set occurs... */
850 || loop_reg_used_before_p (set, p, loop_start,
852 /* And the register is used in basic blocks other
853 than the one where it is set (meaning that
854 something after this point in the loop might
855 depend on its value before the set). */
856 && !reg_in_basic_block_p (p, SET_DEST (set)))
857 /* It is unsafe to move the set. The fact that these
858 three conditions are considered in conjunction means
859 that we are assuming various conditions, such as:
861 o It's OK to move a set of a variable which was not
862 created by the user and is not used in an exit test
863 even if that point in the set would not be reached
864 during execution of the loop. */
866 else if ((tem = invariant_p (src))
867 && (dependencies == 0
868 || (tem2 = invariant_p (dependencies)) != 0)
869 && (VARRAY_INT (n_times_set,
870 REGNO (SET_DEST (set))) == 1
872 = consec_sets_invariant_p
874 VARRAY_INT (n_times_set, REGNO (SET_DEST (set))),
876 /* If the insn can cause a trap (such as divide by zero),
877 can't move it unless it's guaranteed to be executed
878 once loop is entered. Even a function call might
879 prevent the trap insn from being reached
880 (since it might exit!) */
881 && ! ((maybe_never || call_passed)
882 && may_trap_p (src)))
884 register struct movable *m;
885 register int regno = REGNO (SET_DEST (set));
887 /* A potential lossage is where we have a case where two insns
888 can be combined as long as they are both in the loop, but
889 we move one of them outside the loop. For large loops,
890 this can lose. The most common case of this is the address
891 of a function being called.
893 Therefore, if this register is marked as being used exactly
894 once if we are in a loop with calls (a "large loop"), see if
895 we can replace the usage of this register with the source
896 of this SET. If we can, delete this insn.
898 Don't do this if P has a REG_RETVAL note or if we have
899 SMALL_REGISTER_CLASSES and SET_SRC is a hard register. */
901 if (reg_single_usage && VARRAY_RTX (reg_single_usage, regno) != 0
902 && VARRAY_RTX (reg_single_usage, regno) != const0_rtx
903 && REGNO_FIRST_UID (regno) == INSN_UID (p)
904 && (REGNO_LAST_UID (regno)
905 == INSN_UID (VARRAY_RTX (reg_single_usage, regno)))
906 && VARRAY_INT (n_times_set, regno) == 1
907 && ! side_effects_p (SET_SRC (set))
908 && ! find_reg_note (p, REG_RETVAL, NULL_RTX)
909 && (! SMALL_REGISTER_CLASSES
910 || (! (GET_CODE (SET_SRC (set)) == REG
911 && REGNO (SET_SRC (set)) < FIRST_PSEUDO_REGISTER)))
912 /* This test is not redundant; SET_SRC (set) might be
913 a call-clobbered register and the life of REGNO
914 might span a call. */
915 && ! modified_between_p (SET_SRC (set), p,
917 (reg_single_usage, regno))
918 && no_labels_between_p (p, VARRAY_RTX (reg_single_usage, regno))
919 && validate_replace_rtx (SET_DEST (set), SET_SRC (set),
921 (reg_single_usage, regno)))
923 /* Replace any usage in a REG_EQUAL note. Must copy the
924 new source, so that we don't get rtx sharing between the
925 SET_SOURCE and REG_NOTES of insn p. */
926 REG_NOTES (VARRAY_RTX (reg_single_usage, regno))
927 = replace_rtx (REG_NOTES (VARRAY_RTX
928 (reg_single_usage, regno)),
929 SET_DEST (set), copy_rtx (SET_SRC (set)));
932 NOTE_LINE_NUMBER (p) = NOTE_INSN_DELETED;
933 NOTE_SOURCE_FILE (p) = 0;
934 VARRAY_INT (n_times_set, regno) = 0;
938 m = (struct movable *) alloca (sizeof (struct movable));
942 m->dependencies = dependencies;
943 m->set_dest = SET_DEST (set);
945 m->consec = VARRAY_INT (n_times_set,
946 REGNO (SET_DEST (set))) - 1;
950 m->move_insn = move_insn;
951 m->move_insn_first = 0;
952 m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0);
953 m->savemode = VOIDmode;
955 /* Set M->cond if either invariant_p or consec_sets_invariant_p
956 returned 2 (only conditionally invariant). */
957 m->cond = ((tem | tem1 | tem2) > 1);
958 m->global = (uid_luid[REGNO_LAST_UID (regno)] > INSN_LUID (end)
959 || uid_luid[REGNO_FIRST_UID (regno)] < INSN_LUID (loop_start));
961 m->lifetime = (uid_luid[REGNO_LAST_UID (regno)]
962 - uid_luid[REGNO_FIRST_UID (regno)]);
963 m->savings = VARRAY_INT (n_times_used, regno);
964 if (find_reg_note (p, REG_RETVAL, NULL_RTX))
965 m->savings += libcall_benefit (p);
966 VARRAY_INT (n_times_set, regno) = move_insn ? -2 : -1;
967 /* Add M to the end of the chain MOVABLES. */
971 last_movable->next = m;
976 /* It is possible for the first instruction to have a
977 REG_EQUAL note but a non-invariant SET_SRC, so we must
978 remember the status of the first instruction in case
979 the last instruction doesn't have a REG_EQUAL note. */
980 m->move_insn_first = m->move_insn;
982 /* Skip this insn, not checking REG_LIBCALL notes. */
983 p = next_nonnote_insn (p);
984 /* Skip the consecutive insns, if there are any. */
985 p = skip_consec_insns (p, m->consec);
986 /* Back up to the last insn of the consecutive group. */
987 p = prev_nonnote_insn (p);
989 /* We must now reset m->move_insn, m->is_equiv, and possibly
990 m->set_src to correspond to the effects of all the
992 temp = find_reg_note (p, REG_EQUIV, NULL_RTX);
994 m->set_src = XEXP (temp, 0), m->move_insn = 1;
997 temp = find_reg_note (p, REG_EQUAL, NULL_RTX);
998 if (temp && CONSTANT_P (XEXP (temp, 0)))
999 m->set_src = XEXP (temp, 0), m->move_insn = 1;
1004 m->is_equiv = (find_reg_note (p, REG_EQUIV, NULL_RTX) != 0);
1007 /* If this register is always set within a STRICT_LOW_PART
1008 or set to zero, then its high bytes are constant.
1009 So clear them outside the loop and within the loop
1010 just load the low bytes.
1011 We must check that the machine has an instruction to do so.
1012 Also, if the value loaded into the register
1013 depends on the same register, this cannot be done. */
1014 else if (SET_SRC (set) == const0_rtx
1015 && GET_CODE (NEXT_INSN (p)) == INSN
1016 && (set1 = single_set (NEXT_INSN (p)))
1017 && GET_CODE (set1) == SET
1018 && (GET_CODE (SET_DEST (set1)) == STRICT_LOW_PART)
1019 && (GET_CODE (XEXP (SET_DEST (set1), 0)) == SUBREG)
1020 && (SUBREG_REG (XEXP (SET_DEST (set1), 0))
1022 && !reg_mentioned_p (SET_DEST (set), SET_SRC (set1)))
1024 register int regno = REGNO (SET_DEST (set));
1025 if (VARRAY_INT (n_times_set, regno) == 2)
1027 register struct movable *m;
1028 m = (struct movable *) alloca (sizeof (struct movable));
1031 m->set_dest = SET_DEST (set);
1032 m->dependencies = 0;
1038 m->move_insn_first = 0;
1040 /* If the insn may not be executed on some cycles,
1041 we can't clear the whole reg; clear just high part.
1042 Not even if the reg is used only within this loop.
1049 Clearing x before the inner loop could clobber a value
1050 being saved from the last time around the outer loop.
1051 However, if the reg is not used outside this loop
1052 and all uses of the register are in the same
1053 basic block as the store, there is no problem.
1055 If this insn was made by loop, we don't know its
1056 INSN_LUID and hence must make a conservative
1058 m->global = (INSN_UID (p) >= max_uid_for_loop
1059 || (uid_luid[REGNO_LAST_UID (regno)]
1061 || (uid_luid[REGNO_FIRST_UID (regno)]
1063 || (labels_in_range_p
1064 (p, uid_luid[REGNO_FIRST_UID (regno)])));
1065 if (maybe_never && m->global)
1066 m->savemode = GET_MODE (SET_SRC (set1));
1068 m->savemode = VOIDmode;
1072 m->lifetime = (uid_luid[REGNO_LAST_UID (regno)]
1073 - uid_luid[REGNO_FIRST_UID (regno)]);
1075 VARRAY_INT (n_times_set, regno) = -1;
1076 /* Add M to the end of the chain MOVABLES. */
1080 last_movable->next = m;
1085 /* Past a call insn, we get to insns which might not be executed
1086 because the call might exit. This matters for insns that trap.
1087 Call insns inside a REG_LIBCALL/REG_RETVAL block always return,
1088 so they don't count. */
1089 else if (GET_CODE (p) == CALL_INSN && ! in_libcall)
1091 /* Past a label or a jump, we get to insns for which we
1092 can't count on whether or how many times they will be
1093 executed during each iteration. Therefore, we can
1094 only move out sets of trivial variables
1095 (those not used after the loop). */
1096 /* Similar code appears twice in strength_reduce. */
1097 else if ((GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN)
1098 /* If we enter the loop in the middle, and scan around to the
1099 beginning, don't set maybe_never for that. This must be an
1100 unconditional jump, otherwise the code at the top of the
1101 loop might never be executed. Unconditional jumps are
1102 followed a by barrier then loop end. */
1103 && ! (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == loop_top
1104 && NEXT_INSN (NEXT_INSN (p)) == end
1105 && simplejump_p (p)))
1107 else if (GET_CODE (p) == NOTE)
1109 /* At the virtual top of a converted loop, insns are again known to
1110 be executed: logically, the loop begins here even though the exit
1111 code has been duplicated. */
1112 if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0)
1113 maybe_never = call_passed = 0;
1114 else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
1116 else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
1121 /* If one movable subsumes another, ignore that other. */
1123 ignore_some_movables (movables);
1125 /* For each movable insn, see if the reg that it loads
1126 leads when it dies right into another conditionally movable insn.
1127 If so, record that the second insn "forces" the first one,
1128 since the second can be moved only if the first is. */
1130 force_movables (movables);
1132 /* See if there are multiple movable insns that load the same value.
1133 If there are, make all but the first point at the first one
1134 through the `match' field, and add the priorities of them
1135 all together as the priority of the first. */
1137 combine_movables (movables, nregs);
1139 /* Now consider each movable insn to decide whether it is worth moving.
1140 Store 0 in n_times_set for each reg that is moved.
1142 Generally this increases code size, so do not move moveables when
1143 optimizing for code size. */
1145 if (! optimize_size)
1146 move_movables (movables, threshold,
1147 insn_count, loop_start, end, nregs);
1149 /* Now candidates that still are negative are those not moved.
1150 Change n_times_set to indicate that those are not actually invariant. */
1151 for (i = 0; i < nregs; i++)
1152 if (VARRAY_INT (n_times_set, i) < 0)
1153 VARRAY_INT (n_times_set, i) = VARRAY_INT (n_times_used, i);
1155 /* Now that we've moved some things out of the loop, we able to
1156 hoist even more memory references. There's no need to pass
1157 reg_single_usage this time, since we're done with it. */
1158 load_mems_and_recount_loop_regs_set (scan_start, end, loop_top,
1162 if (flag_strength_reduce)
1164 the_movables = movables;
1165 strength_reduce (scan_start, end, loop_top,
1166 insn_count, loop_start, end, unroll_p, bct_p);
1169 VARRAY_FREE (n_times_set);
1170 VARRAY_FREE (n_times_used);
1171 VARRAY_FREE (may_not_optimize);
1172 VARRAY_FREE (reg_single_usage);
1175 /* Add elements to *OUTPUT to record all the pseudo-regs
1176 mentioned in IN_THIS but not mentioned in NOT_IN_THIS. */
1179 record_excess_regs (in_this, not_in_this, output)
1180 rtx in_this, not_in_this;
1187 code = GET_CODE (in_this);
1201 if (REGNO (in_this) >= FIRST_PSEUDO_REGISTER
1202 && ! reg_mentioned_p (in_this, not_in_this))
1203 *output = gen_rtx_EXPR_LIST (VOIDmode, in_this, *output);
1210 fmt = GET_RTX_FORMAT (code);
1211 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1218 for (j = 0; j < XVECLEN (in_this, i); j++)
1219 record_excess_regs (XVECEXP (in_this, i, j), not_in_this, output);
1223 record_excess_regs (XEXP (in_this, i), not_in_this, output);
1229 /* Check what regs are referred to in the libcall block ending with INSN,
1230 aside from those mentioned in the equivalent value.
1231 If there are none, return 0.
1232 If there are one or more, return an EXPR_LIST containing all of them. */
1235 libcall_other_reg (insn, equiv)
1238 rtx note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
1239 rtx p = XEXP (note, 0);
1242 /* First, find all the regs used in the libcall block
1243 that are not mentioned as inputs to the result. */
1247 if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
1248 || GET_CODE (p) == CALL_INSN)
1249 record_excess_regs (PATTERN (p), equiv, &output);
1256 /* Return 1 if all uses of REG
1257 are between INSN and the end of the basic block. */
1260 reg_in_basic_block_p (insn, reg)
1263 int regno = REGNO (reg);
1266 if (REGNO_FIRST_UID (regno) != INSN_UID (insn))
1269 /* Search this basic block for the already recorded last use of the reg. */
1270 for (p = insn; p; p = NEXT_INSN (p))
1272 switch (GET_CODE (p))
1279 /* Ordinary insn: if this is the last use, we win. */
1280 if (REGNO_LAST_UID (regno) == INSN_UID (p))
1285 /* Jump insn: if this is the last use, we win. */
1286 if (REGNO_LAST_UID (regno) == INSN_UID (p))
1288 /* Otherwise, it's the end of the basic block, so we lose. */
1293 /* It's the end of the basic block, so we lose. */
1301 /* The "last use" doesn't follow the "first use"?? */
1305 /* Compute the benefit of eliminating the insns in the block whose
1306 last insn is LAST. This may be a group of insns used to compute a
1307 value directly or can contain a library call. */
1310 libcall_benefit (last)
1316 for (insn = XEXP (find_reg_note (last, REG_RETVAL, NULL_RTX), 0);
1317 insn != last; insn = NEXT_INSN (insn))
1319 if (GET_CODE (insn) == CALL_INSN)
1320 benefit += 10; /* Assume at least this many insns in a library
1322 else if (GET_CODE (insn) == INSN
1323 && GET_CODE (PATTERN (insn)) != USE
1324 && GET_CODE (PATTERN (insn)) != CLOBBER)
1331 /* Skip COUNT insns from INSN, counting library calls as 1 insn. */
1334 skip_consec_insns (insn, count)
1338 for (; count > 0; count--)
1342 /* If first insn of libcall sequence, skip to end. */
1343 /* Do this at start of loop, since INSN is guaranteed to
1345 if (GET_CODE (insn) != NOTE
1346 && (temp = find_reg_note (insn, REG_LIBCALL, NULL_RTX)))
1347 insn = XEXP (temp, 0);
1349 do insn = NEXT_INSN (insn);
1350 while (GET_CODE (insn) == NOTE);
1356 /* Ignore any movable whose insn falls within a libcall
1357 which is part of another movable.
1358 We make use of the fact that the movable for the libcall value
1359 was made later and so appears later on the chain. */
1362 ignore_some_movables (movables)
1363 struct movable *movables;
1365 register struct movable *m, *m1;
1367 for (m = movables; m; m = m->next)
1369 /* Is this a movable for the value of a libcall? */
1370 rtx note = find_reg_note (m->insn, REG_RETVAL, NULL_RTX);
1374 /* Check for earlier movables inside that range,
1375 and mark them invalid. We cannot use LUIDs here because
1376 insns created by loop.c for prior loops don't have LUIDs.
1377 Rather than reject all such insns from movables, we just
1378 explicitly check each insn in the libcall (since invariant
1379 libcalls aren't that common). */
1380 for (insn = XEXP (note, 0); insn != m->insn; insn = NEXT_INSN (insn))
1381 for (m1 = movables; m1 != m; m1 = m1->next)
1382 if (m1->insn == insn)
1388 /* For each movable insn, see if the reg that it loads
1389 leads when it dies right into another conditionally movable insn.
1390 If so, record that the second insn "forces" the first one,
1391 since the second can be moved only if the first is. */
1394 force_movables (movables)
1395 struct movable *movables;
1397 register struct movable *m, *m1;
1398 for (m1 = movables; m1; m1 = m1->next)
1399 /* Omit this if moving just the (SET (REG) 0) of a zero-extend. */
1400 if (!m1->partial && !m1->done)
1402 int regno = m1->regno;
1403 for (m = m1->next; m; m = m->next)
1404 /* ??? Could this be a bug? What if CSE caused the
1405 register of M1 to be used after this insn?
1406 Since CSE does not update regno_last_uid,
1407 this insn M->insn might not be where it dies.
1408 But very likely this doesn't matter; what matters is
1409 that M's reg is computed from M1's reg. */
1410 if (INSN_UID (m->insn) == REGNO_LAST_UID (regno)
1413 if (m != 0 && m->set_src == m1->set_dest
1414 /* If m->consec, m->set_src isn't valid. */
1418 /* Increase the priority of the moving the first insn
1419 since it permits the second to be moved as well. */
1423 m1->lifetime += m->lifetime;
1424 m1->savings += m->savings;
1429 /* Find invariant expressions that are equal and can be combined into
1433 combine_movables (movables, nregs)
1434 struct movable *movables;
1437 register struct movable *m;
1438 char *matched_regs = (char *) alloca (nregs);
1439 enum machine_mode mode;
1441 /* Regs that are set more than once are not allowed to match
1442 or be matched. I'm no longer sure why not. */
1443 /* Perhaps testing m->consec_sets would be more appropriate here? */
1445 for (m = movables; m; m = m->next)
1446 if (m->match == 0 && VARRAY_INT (n_times_used, m->regno) == 1 && !m->partial)
1448 register struct movable *m1;
1449 int regno = m->regno;
1451 bzero (matched_regs, nregs);
1452 matched_regs[regno] = 1;
1454 /* We want later insns to match the first one. Don't make the first
1455 one match any later ones. So start this loop at m->next. */
1456 for (m1 = m->next; m1; m1 = m1->next)
1457 if (m != m1 && m1->match == 0 && VARRAY_INT (n_times_used, m1->regno) == 1
1458 /* A reg used outside the loop mustn't be eliminated. */
1460 /* A reg used for zero-extending mustn't be eliminated. */
1462 && (matched_regs[m1->regno]
1465 /* Can combine regs with different modes loaded from the
1466 same constant only if the modes are the same or
1467 if both are integer modes with M wider or the same
1468 width as M1. The check for integer is redundant, but
1469 safe, since the only case of differing destination
1470 modes with equal sources is when both sources are
1471 VOIDmode, i.e., CONST_INT. */
1472 (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest)
1473 || (GET_MODE_CLASS (GET_MODE (m->set_dest)) == MODE_INT
1474 && GET_MODE_CLASS (GET_MODE (m1->set_dest)) == MODE_INT
1475 && (GET_MODE_BITSIZE (GET_MODE (m->set_dest))
1476 >= GET_MODE_BITSIZE (GET_MODE (m1->set_dest)))))
1477 /* See if the source of M1 says it matches M. */
1478 && ((GET_CODE (m1->set_src) == REG
1479 && matched_regs[REGNO (m1->set_src)])
1480 || rtx_equal_for_loop_p (m->set_src, m1->set_src,
1482 && ((m->dependencies == m1->dependencies)
1483 || rtx_equal_p (m->dependencies, m1->dependencies)))
1485 m->lifetime += m1->lifetime;
1486 m->savings += m1->savings;
1489 matched_regs[m1->regno] = 1;
1493 /* Now combine the regs used for zero-extension.
1494 This can be done for those not marked `global'
1495 provided their lives don't overlap. */
1497 for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
1498 mode = GET_MODE_WIDER_MODE (mode))
1500 register struct movable *m0 = 0;
1502 /* Combine all the registers for extension from mode MODE.
1503 Don't combine any that are used outside this loop. */
1504 for (m = movables; m; m = m->next)
1505 if (m->partial && ! m->global
1506 && mode == GET_MODE (SET_SRC (PATTERN (NEXT_INSN (m->insn)))))
1508 register struct movable *m1;
1509 int first = uid_luid[REGNO_FIRST_UID (m->regno)];
1510 int last = uid_luid[REGNO_LAST_UID (m->regno)];
1514 /* First one: don't check for overlap, just record it. */
1519 /* Make sure they extend to the same mode.
1520 (Almost always true.) */
1521 if (GET_MODE (m->set_dest) != GET_MODE (m0->set_dest))
1524 /* We already have one: check for overlap with those
1525 already combined together. */
1526 for (m1 = movables; m1 != m; m1 = m1->next)
1527 if (m1 == m0 || (m1->partial && m1->match == m0))
1528 if (! (uid_luid[REGNO_FIRST_UID (m1->regno)] > last
1529 || uid_luid[REGNO_LAST_UID (m1->regno)] < first))
1532 /* No overlap: we can combine this with the others. */
1533 m0->lifetime += m->lifetime;
1534 m0->savings += m->savings;
1543 /* Return 1 if regs X and Y will become the same if moved. */
1546 regs_match_p (x, y, movables)
1548 struct movable *movables;
1552 struct movable *mx, *my;
1554 for (mx = movables; mx; mx = mx->next)
1555 if (mx->regno == xn)
1558 for (my = movables; my; my = my->next)
1559 if (my->regno == yn)
1563 && ((mx->match == my->match && mx->match != 0)
1565 || mx == my->match));
1568 /* Return 1 if X and Y are identical-looking rtx's.
1569 This is the Lisp function EQUAL for rtx arguments.
1571 If two registers are matching movables or a movable register and an
1572 equivalent constant, consider them equal. */
1575 rtx_equal_for_loop_p (x, y, movables)
1577 struct movable *movables;
1581 register struct movable *m;
1582 register enum rtx_code code;
1587 if (x == 0 || y == 0)
1590 code = GET_CODE (x);
1592 /* If we have a register and a constant, they may sometimes be
1594 if (GET_CODE (x) == REG && VARRAY_INT (n_times_set, REGNO (x)) == -2
1597 for (m = movables; m; m = m->next)
1598 if (m->move_insn && m->regno == REGNO (x)
1599 && rtx_equal_p (m->set_src, y))
1602 else if (GET_CODE (y) == REG && VARRAY_INT (n_times_set, REGNO (y)) == -2
1605 for (m = movables; m; m = m->next)
1606 if (m->move_insn && m->regno == REGNO (y)
1607 && rtx_equal_p (m->set_src, x))
1611 /* Otherwise, rtx's of different codes cannot be equal. */
1612 if (code != GET_CODE (y))
1615 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
1616 (REG:SI x) and (REG:HI x) are NOT equivalent. */
1618 if (GET_MODE (x) != GET_MODE (y))
1621 /* These three types of rtx's can be compared nonrecursively. */
1623 return (REGNO (x) == REGNO (y) || regs_match_p (x, y, movables));
1625 if (code == LABEL_REF)
1626 return XEXP (x, 0) == XEXP (y, 0);
1627 if (code == SYMBOL_REF)
1628 return XSTR (x, 0) == XSTR (y, 0);
1630 /* Compare the elements. If any pair of corresponding elements
1631 fail to match, return 0 for the whole things. */
1633 fmt = GET_RTX_FORMAT (code);
1634 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1639 if (XWINT (x, i) != XWINT (y, i))
1644 if (XINT (x, i) != XINT (y, i))
1649 /* Two vectors must have the same length. */
1650 if (XVECLEN (x, i) != XVECLEN (y, i))
1653 /* And the corresponding elements must match. */
1654 for (j = 0; j < XVECLEN (x, i); j++)
1655 if (rtx_equal_for_loop_p (XVECEXP (x, i, j), XVECEXP (y, i, j), movables) == 0)
1660 if (rtx_equal_for_loop_p (XEXP (x, i), XEXP (y, i), movables) == 0)
1665 if (strcmp (XSTR (x, i), XSTR (y, i)))
1670 /* These are just backpointers, so they don't matter. */
1676 /* It is believed that rtx's at this level will never
1677 contain anything but integers and other rtx's,
1678 except for within LABEL_REFs and SYMBOL_REFs. */
1686 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to all
1687 insns in INSNS which use thet reference. */
1690 add_label_notes (x, insns)
1694 enum rtx_code code = GET_CODE (x);
1699 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
1701 /* This code used to ignore labels that referred to dispatch tables to
1702 avoid flow generating (slighly) worse code.
1704 We no longer ignore such label references (see LABEL_REF handling in
1705 mark_jump_label for additional information). */
1706 for (insn = insns; insn; insn = NEXT_INSN (insn))
1707 if (reg_mentioned_p (XEXP (x, 0), insn))
1708 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_LABEL, XEXP (x, 0),
1712 fmt = GET_RTX_FORMAT (code);
1713 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1716 add_label_notes (XEXP (x, i), insns);
1717 else if (fmt[i] == 'E')
1718 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
1719 add_label_notes (XVECEXP (x, i, j), insns);
1723 /* Scan MOVABLES, and move the insns that deserve to be moved.
1724 If two matching movables are combined, replace one reg with the
1725 other throughout. */
1728 move_movables (movables, threshold, insn_count, loop_start, end, nregs)
1729 struct movable *movables;
1737 register struct movable *m;
1739 /* Map of pseudo-register replacements to handle combining
1740 when we move several insns that load the same value
1741 into different pseudo-registers. */
1742 rtx *reg_map = (rtx *) alloca (nregs * sizeof (rtx));
1743 char *already_moved = (char *) alloca (nregs);
1745 bzero (already_moved, nregs);
1746 bzero ((char *) reg_map, nregs * sizeof (rtx));
1750 for (m = movables; m; m = m->next)
1752 /* Describe this movable insn. */
1754 if (loop_dump_stream)
1756 fprintf (loop_dump_stream, "Insn %d: regno %d (life %d), ",
1757 INSN_UID (m->insn), m->regno, m->lifetime);
1759 fprintf (loop_dump_stream, "consec %d, ", m->consec);
1761 fprintf (loop_dump_stream, "cond ");
1763 fprintf (loop_dump_stream, "force ");
1765 fprintf (loop_dump_stream, "global ");
1767 fprintf (loop_dump_stream, "done ");
1769 fprintf (loop_dump_stream, "move-insn ");
1771 fprintf (loop_dump_stream, "matches %d ",
1772 INSN_UID (m->match->insn));
1774 fprintf (loop_dump_stream, "forces %d ",
1775 INSN_UID (m->forces->insn));
1778 /* Count movables. Value used in heuristics in strength_reduce. */
1781 /* Ignore the insn if it's already done (it matched something else).
1782 Otherwise, see if it is now safe to move. */
1786 || (1 == invariant_p (m->set_src)
1787 && (m->dependencies == 0
1788 || 1 == invariant_p (m->dependencies))
1790 || 1 == consec_sets_invariant_p (m->set_dest,
1793 && (! m->forces || m->forces->done))
1797 int savings = m->savings;
1799 /* We have an insn that is safe to move.
1800 Compute its desirability. */
1805 if (loop_dump_stream)
1806 fprintf (loop_dump_stream, "savings %d ", savings);
1808 if (moved_once[regno] && loop_dump_stream)
1809 fprintf (loop_dump_stream, "halved since already moved ");
1811 /* An insn MUST be moved if we already moved something else
1812 which is safe only if this one is moved too: that is,
1813 if already_moved[REGNO] is nonzero. */
1815 /* An insn is desirable to move if the new lifetime of the
1816 register is no more than THRESHOLD times the old lifetime.
1817 If it's not desirable, it means the loop is so big
1818 that moving won't speed things up much,
1819 and it is liable to make register usage worse. */
1821 /* It is also desirable to move if it can be moved at no
1822 extra cost because something else was already moved. */
1824 if (already_moved[regno]
1825 || flag_move_all_movables
1826 || (threshold * savings * m->lifetime) >=
1827 (moved_once[regno] ? insn_count * 2 : insn_count)
1828 || (m->forces && m->forces->done
1829 && VARRAY_INT (n_times_used, m->forces->regno) == 1))
1832 register struct movable *m1;
1835 /* Now move the insns that set the reg. */
1837 if (m->partial && m->match)
1841 /* Find the end of this chain of matching regs.
1842 Thus, we load each reg in the chain from that one reg.
1843 And that reg is loaded with 0 directly,
1844 since it has ->match == 0. */
1845 for (m1 = m; m1->match; m1 = m1->match);
1846 newpat = gen_move_insn (SET_DEST (PATTERN (m->insn)),
1847 SET_DEST (PATTERN (m1->insn)));
1848 i1 = emit_insn_before (newpat, loop_start);
1850 /* Mark the moved, invariant reg as being allowed to
1851 share a hard reg with the other matching invariant. */
1852 REG_NOTES (i1) = REG_NOTES (m->insn);
1853 r1 = SET_DEST (PATTERN (m->insn));
1854 r2 = SET_DEST (PATTERN (m1->insn));
1856 = gen_rtx_EXPR_LIST (VOIDmode, r1,
1857 gen_rtx_EXPR_LIST (VOIDmode, r2,
1859 delete_insn (m->insn);
1864 if (loop_dump_stream)
1865 fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1));
1867 /* If we are to re-generate the item being moved with a
1868 new move insn, first delete what we have and then emit
1869 the move insn before the loop. */
1870 else if (m->move_insn)
1874 for (count = m->consec; count >= 0; count--)
1876 /* If this is the first insn of a library call sequence,
1878 if (GET_CODE (p) != NOTE
1879 && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
1882 /* If this is the last insn of a libcall sequence, then
1883 delete every insn in the sequence except the last.
1884 The last insn is handled in the normal manner. */
1885 if (GET_CODE (p) != NOTE
1886 && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX)))
1888 temp = XEXP (temp, 0);
1890 temp = delete_insn (temp);
1894 p = delete_insn (p);
1896 /* simplify_giv_expr expects that it can walk the insns
1897 at m->insn forwards and see this old sequence we are
1898 tossing here. delete_insn does preserve the next
1899 pointers, but when we skip over a NOTE we must fix
1900 it up. Otherwise that code walks into the non-deleted
1902 while (p && GET_CODE (p) == NOTE)
1903 p = NEXT_INSN (temp) = NEXT_INSN (p);
1907 emit_move_insn (m->set_dest, m->set_src);
1908 temp = get_insns ();
1911 add_label_notes (m->set_src, temp);
1913 i1 = emit_insns_before (temp, loop_start);
1914 if (! find_reg_note (i1, REG_EQUAL, NULL_RTX))
1916 = gen_rtx_EXPR_LIST (m->is_equiv ? REG_EQUIV : REG_EQUAL,
1917 m->set_src, REG_NOTES (i1));
1919 if (loop_dump_stream)
1920 fprintf (loop_dump_stream, " moved to %d", INSN_UID (i1));
1922 /* The more regs we move, the less we like moving them. */
1927 for (count = m->consec; count >= 0; count--)
1931 /* If first insn of libcall sequence, skip to end. */
1932 /* Do this at start of loop, since p is guaranteed to
1934 if (GET_CODE (p) != NOTE
1935 && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
1938 /* If last insn of libcall sequence, move all
1939 insns except the last before the loop. The last
1940 insn is handled in the normal manner. */
1941 if (GET_CODE (p) != NOTE
1942 && (temp = find_reg_note (p, REG_RETVAL, NULL_RTX)))
1946 rtx fn_address_insn = 0;
1949 for (temp = XEXP (temp, 0); temp != p;
1950 temp = NEXT_INSN (temp))
1956 if (GET_CODE (temp) == NOTE)
1959 body = PATTERN (temp);
1961 /* Find the next insn after TEMP,
1962 not counting USE or NOTE insns. */
1963 for (next = NEXT_INSN (temp); next != p;
1964 next = NEXT_INSN (next))
1965 if (! (GET_CODE (next) == INSN
1966 && GET_CODE (PATTERN (next)) == USE)
1967 && GET_CODE (next) != NOTE)
1970 /* If that is the call, this may be the insn
1971 that loads the function address.
1973 Extract the function address from the insn
1974 that loads it into a register.
1975 If this insn was cse'd, we get incorrect code.
1977 So emit a new move insn that copies the
1978 function address into the register that the
1979 call insn will use. flow.c will delete any
1980 redundant stores that we have created. */
1981 if (GET_CODE (next) == CALL_INSN
1982 && GET_CODE (body) == SET
1983 && GET_CODE (SET_DEST (body)) == REG
1984 && (n = find_reg_note (temp, REG_EQUAL,
1987 fn_reg = SET_SRC (body);
1988 if (GET_CODE (fn_reg) != REG)
1989 fn_reg = SET_DEST (body);
1990 fn_address = XEXP (n, 0);
1991 fn_address_insn = temp;
1993 /* We have the call insn.
1994 If it uses the register we suspect it might,
1995 load it with the correct address directly. */
1996 if (GET_CODE (temp) == CALL_INSN
1998 && reg_referenced_p (fn_reg, body))
1999 emit_insn_after (gen_move_insn (fn_reg,
2003 if (GET_CODE (temp) == CALL_INSN)
2005 i1 = emit_call_insn_before (body, loop_start);
2006 /* Because the USAGE information potentially
2007 contains objects other than hard registers
2008 we need to copy it. */
2009 if (CALL_INSN_FUNCTION_USAGE (temp))
2010 CALL_INSN_FUNCTION_USAGE (i1)
2011 = copy_rtx (CALL_INSN_FUNCTION_USAGE (temp));
2014 i1 = emit_insn_before (body, loop_start);
2017 if (temp == fn_address_insn)
2018 fn_address_insn = i1;
2019 REG_NOTES (i1) = REG_NOTES (temp);
2023 if (m->savemode != VOIDmode)
2025 /* P sets REG to zero; but we should clear only
2026 the bits that are not covered by the mode
2028 rtx reg = m->set_dest;
2034 (GET_MODE (reg), and_optab, reg,
2035 GEN_INT ((((HOST_WIDE_INT) 1
2036 << GET_MODE_BITSIZE (m->savemode)))
2038 reg, 1, OPTAB_LIB_WIDEN);
2042 emit_move_insn (reg, tem);
2043 sequence = gen_sequence ();
2045 i1 = emit_insn_before (sequence, loop_start);
2047 else if (GET_CODE (p) == CALL_INSN)
2049 i1 = emit_call_insn_before (PATTERN (p), loop_start);
2050 /* Because the USAGE information potentially
2051 contains objects other than hard registers
2052 we need to copy it. */
2053 if (CALL_INSN_FUNCTION_USAGE (p))
2054 CALL_INSN_FUNCTION_USAGE (i1)
2055 = copy_rtx (CALL_INSN_FUNCTION_USAGE (p));
2057 else if (count == m->consec && m->move_insn_first)
2059 /* The SET_SRC might not be invariant, so we must
2060 use the REG_EQUAL note. */
2062 emit_move_insn (m->set_dest, m->set_src);
2063 temp = get_insns ();
2066 add_label_notes (m->set_src, temp);
2068 i1 = emit_insns_before (temp, loop_start);
2069 if (! find_reg_note (i1, REG_EQUAL, NULL_RTX))
2071 = gen_rtx_EXPR_LIST ((m->is_equiv ? REG_EQUIV
2073 m->set_src, REG_NOTES (i1));
2076 i1 = emit_insn_before (PATTERN (p), loop_start);
2078 if (REG_NOTES (i1) == 0)
2080 REG_NOTES (i1) = REG_NOTES (p);
2082 /* If there is a REG_EQUAL note present whose value
2083 is not loop invariant, then delete it, since it
2084 may cause problems with later optimization passes.
2085 It is possible for cse to create such notes
2086 like this as a result of record_jump_cond. */
2088 if ((temp = find_reg_note (i1, REG_EQUAL, NULL_RTX))
2089 && ! invariant_p (XEXP (temp, 0)))
2090 remove_note (i1, temp);
2096 if (loop_dump_stream)
2097 fprintf (loop_dump_stream, " moved to %d",
2100 /* If library call, now fix the REG_NOTES that contain
2101 insn pointers, namely REG_LIBCALL on FIRST
2102 and REG_RETVAL on I1. */
2103 if ((temp = find_reg_note (i1, REG_RETVAL, NULL_RTX)))
2105 XEXP (temp, 0) = first;
2106 temp = find_reg_note (first, REG_LIBCALL, NULL_RTX);
2107 XEXP (temp, 0) = i1;
2114 /* simplify_giv_expr expects that it can walk the insns
2115 at m->insn forwards and see this old sequence we are
2116 tossing here. delete_insn does preserve the next
2117 pointers, but when we skip over a NOTE we must fix
2118 it up. Otherwise that code walks into the non-deleted
2120 while (p && GET_CODE (p) == NOTE)
2121 p = NEXT_INSN (temp) = NEXT_INSN (p);
2124 /* The more regs we move, the less we like moving them. */
2128 /* Any other movable that loads the same register
2130 already_moved[regno] = 1;
2132 /* This reg has been moved out of one loop. */
2133 moved_once[regno] = 1;
2135 /* The reg set here is now invariant. */
2137 VARRAY_INT (n_times_set, regno) = 0;
2141 /* Change the length-of-life info for the register
2142 to say it lives at least the full length of this loop.
2143 This will help guide optimizations in outer loops. */
2145 if (uid_luid[REGNO_FIRST_UID (regno)] > INSN_LUID (loop_start))
2146 /* This is the old insn before all the moved insns.
2147 We can't use the moved insn because it is out of range
2148 in uid_luid. Only the old insns have luids. */
2149 REGNO_FIRST_UID (regno) = INSN_UID (loop_start);
2150 if (uid_luid[REGNO_LAST_UID (regno)] < INSN_LUID (end))
2151 REGNO_LAST_UID (regno) = INSN_UID (end);
2153 /* Combine with this moved insn any other matching movables. */
2156 for (m1 = movables; m1; m1 = m1->next)
2161 /* Schedule the reg loaded by M1
2162 for replacement so that shares the reg of M.
2163 If the modes differ (only possible in restricted
2164 circumstances, make a SUBREG. */
2165 if (GET_MODE (m->set_dest) == GET_MODE (m1->set_dest))
2166 reg_map[m1->regno] = m->set_dest;
2169 = gen_lowpart_common (GET_MODE (m1->set_dest),
2172 /* Get rid of the matching insn
2173 and prevent further processing of it. */
2176 /* if library call, delete all insn except last, which
2178 if ((temp = find_reg_note (m1->insn, REG_RETVAL,
2181 for (temp = XEXP (temp, 0); temp != m1->insn;
2182 temp = NEXT_INSN (temp))
2185 delete_insn (m1->insn);
2187 /* Any other movable that loads the same register
2189 already_moved[m1->regno] = 1;
2191 /* The reg merged here is now invariant,
2192 if the reg it matches is invariant. */
2194 VARRAY_INT (n_times_set, m1->regno) = 0;
2197 else if (loop_dump_stream)
2198 fprintf (loop_dump_stream, "not desirable");
2200 else if (loop_dump_stream && !m->match)
2201 fprintf (loop_dump_stream, "not safe");
2203 if (loop_dump_stream)
2204 fprintf (loop_dump_stream, "\n");
2208 new_start = loop_start;
2210 /* Go through all the instructions in the loop, making
2211 all the register substitutions scheduled in REG_MAP. */
2212 for (p = new_start; p != end; p = NEXT_INSN (p))
2213 if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
2214 || GET_CODE (p) == CALL_INSN)
2216 replace_regs (PATTERN (p), reg_map, nregs, 0);
2217 replace_regs (REG_NOTES (p), reg_map, nregs, 0);
2223 /* Scan X and replace the address of any MEM in it with ADDR.
2224 REG is the address that MEM should have before the replacement. */
2227 replace_call_address (x, reg, addr)
2230 register enum rtx_code code;
2236 code = GET_CODE (x);
2250 /* Short cut for very common case. */
2251 replace_call_address (XEXP (x, 1), reg, addr);
2255 /* Short cut for very common case. */
2256 replace_call_address (XEXP (x, 0), reg, addr);
2260 /* If this MEM uses a reg other than the one we expected,
2261 something is wrong. */
2262 if (XEXP (x, 0) != reg)
2271 fmt = GET_RTX_FORMAT (code);
2272 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2275 replace_call_address (XEXP (x, i), reg, addr);
2279 for (j = 0; j < XVECLEN (x, i); j++)
2280 replace_call_address (XVECEXP (x, i, j), reg, addr);
2286 /* Return the number of memory refs to addresses that vary
2290 count_nonfixed_reads (x)
2293 register enum rtx_code code;
2301 code = GET_CODE (x);
2315 return ((invariant_p (XEXP (x, 0)) != 1)
2316 + count_nonfixed_reads (XEXP (x, 0)));
2323 fmt = GET_RTX_FORMAT (code);
2324 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
2327 value += count_nonfixed_reads (XEXP (x, i));
2331 for (j = 0; j < XVECLEN (x, i); j++)
2332 value += count_nonfixed_reads (XVECEXP (x, i, j));
2340 /* P is an instruction that sets a register to the result of a ZERO_EXTEND.
2341 Replace it with an instruction to load just the low bytes
2342 if the machine supports such an instruction,
2343 and insert above LOOP_START an instruction to clear the register. */
2346 constant_high_bytes (p, loop_start)
2350 register int insn_code_number;
2352 /* Try to change (SET (REG ...) (ZERO_EXTEND (..:B ...)))
2353 to (SET (STRICT_LOW_PART (SUBREG:B (REG...))) ...). */
2355 new = gen_rtx_SET (VOIDmode,
2356 gen_rtx_STRICT_LOW_PART (VOIDmode,
2357 gen_rtx_SUBREG (GET_MODE (XEXP (SET_SRC (PATTERN (p)), 0)),
2358 SET_DEST (PATTERN (p)),
2360 XEXP (SET_SRC (PATTERN (p)), 0));
2361 insn_code_number = recog (new, p);
2363 if (insn_code_number)
2367 /* Clear destination register before the loop. */
2368 emit_insn_before (gen_rtx_SET (VOIDmode, SET_DEST (PATTERN (p)),
2372 /* Inside the loop, just load the low part. */
2378 /* Scan a loop setting the variables `unknown_address_altered',
2379 `num_mem_sets', `loop_continue', loops_enclosed', `loop_has_call',
2380 and `loop_has_volatile'. Also, fill in the arrays `loop_mems' and
2381 `loop_store_mems'. */
2384 prescan_loop (start, end)
2387 register int level = 1;
2389 int loop_has_multiple_exit_targets = 0;
2390 /* The label after END. Jumping here is just like falling off the
2391 end of the loop. We use next_nonnote_insn instead of next_label
2392 as a hedge against the (pathological) case where some actual insn
2393 might end up between the two. */
2394 rtx exit_target = next_nonnote_insn (end);
2395 if (exit_target == NULL_RTX || GET_CODE (exit_target) != CODE_LABEL)
2396 loop_has_multiple_exit_targets = 1;
2398 unknown_address_altered = 0;
2400 loop_has_volatile = 0;
2401 loop_store_mems_idx = 0;
2408 for (insn = NEXT_INSN (start); insn != NEXT_INSN (end);
2409 insn = NEXT_INSN (insn))
2411 if (GET_CODE (insn) == NOTE)
2413 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
2416 /* Count number of loops contained in this one. */
2419 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
2428 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
2431 loop_continue = insn;
2434 else if (GET_CODE (insn) == CALL_INSN)
2436 if (! CONST_CALL_P (insn))
2437 unknown_address_altered = 1;
2440 else if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN)
2442 rtx label1 = NULL_RTX;
2443 rtx label2 = NULL_RTX;
2445 if (volatile_refs_p (PATTERN (insn)))
2446 loop_has_volatile = 1;
2448 note_stores (PATTERN (insn), note_addr_stored);
2450 if (!loop_has_multiple_exit_targets
2451 && GET_CODE (insn) == JUMP_INSN
2452 && GET_CODE (PATTERN (insn)) == SET
2453 && SET_DEST (PATTERN (insn)) == pc_rtx)
2455 if (GET_CODE (SET_SRC (PATTERN (insn))) == IF_THEN_ELSE)
2457 label1 = XEXP (SET_SRC (PATTERN (insn)), 1);
2458 label2 = XEXP (SET_SRC (PATTERN (insn)), 2);
2462 label1 = SET_SRC (PATTERN (insn));
2466 if (label1 && label1 != pc_rtx)
2468 if (GET_CODE (label1) != LABEL_REF)
2470 /* Something tricky. */
2471 loop_has_multiple_exit_targets = 1;
2474 else if (XEXP (label1, 0) != exit_target
2475 && LABEL_OUTSIDE_LOOP_P (label1))
2477 /* A jump outside the current loop. */
2478 loop_has_multiple_exit_targets = 1;
2488 else if (GET_CODE (insn) == RETURN)
2489 loop_has_multiple_exit_targets = 1;
2492 /* Now, rescan the loop, setting up the LOOP_MEMS array. */
2493 if (/* We can't tell what MEMs are aliased by what. */
2494 !unknown_address_altered
2495 /* An exception thrown by a called function might land us
2498 /* We don't want loads for MEMs moved to a location before the
2499 one at which their stack memory becomes allocated. (Note
2500 that this is not a problem for malloc, etc., since those
2501 require actual function calls. */
2502 && !current_function_calls_alloca
2503 /* There are ways to leave the loop other than falling off the
2505 && !loop_has_multiple_exit_targets)
2506 for (insn = NEXT_INSN (start); insn != NEXT_INSN (end);
2507 insn = NEXT_INSN (insn))
2508 for_each_rtx (&insn, insert_loop_mem, 0);
2511 /* Scan the function looking for loops. Record the start and end of each loop.
2512 Also mark as invalid loops any loops that contain a setjmp or are branched
2513 to from outside the loop. */
2516 find_and_verify_loops (f)
2520 int current_loop = -1;
2524 /* If there are jumps to undefined labels,
2525 treat them as jumps out of any/all loops.
2526 This also avoids writing past end of tables when there are no loops. */
2527 uid_loop_num[0] = -1;
2529 /* Find boundaries of loops, mark which loops are contained within
2530 loops, and invalidate loops that have setjmp. */
2532 for (insn = f; insn; insn = NEXT_INSN (insn))
2534 if (GET_CODE (insn) == NOTE)
2535 switch (NOTE_LINE_NUMBER (insn))
2537 case NOTE_INSN_LOOP_BEG:
2538 loop_number_loop_starts[++next_loop] = insn;
2539 loop_number_loop_ends[next_loop] = 0;
2540 loop_outer_loop[next_loop] = current_loop;
2541 loop_invalid[next_loop] = 0;
2542 loop_number_exit_labels[next_loop] = 0;
2543 loop_number_exit_count[next_loop] = 0;
2544 current_loop = next_loop;
2547 case NOTE_INSN_SETJMP:
2548 /* In this case, we must invalidate our current loop and any
2550 for (loop = current_loop; loop != -1; loop = loop_outer_loop[loop])
2552 loop_invalid[loop] = 1;
2553 if (loop_dump_stream)
2554 fprintf (loop_dump_stream,
2555 "\nLoop at %d ignored due to setjmp.\n",
2556 INSN_UID (loop_number_loop_starts[loop]));
2560 case NOTE_INSN_LOOP_END:
2561 if (current_loop == -1)
2564 loop_number_loop_ends[current_loop] = insn;
2565 current_loop = loop_outer_loop[current_loop];
2572 /* Note that this will mark the NOTE_INSN_LOOP_END note as being in the
2573 enclosing loop, but this doesn't matter. */
2574 uid_loop_num[INSN_UID (insn)] = current_loop;
2577 /* Any loop containing a label used in an initializer must be invalidated,
2578 because it can be jumped into from anywhere. */
2580 for (label = forced_labels; label; label = XEXP (label, 1))
2584 for (loop_num = uid_loop_num[INSN_UID (XEXP (label, 0))];
2586 loop_num = loop_outer_loop[loop_num])
2587 loop_invalid[loop_num] = 1;
2590 /* Any loop containing a label used for an exception handler must be
2591 invalidated, because it can be jumped into from anywhere. */
2593 for (label = exception_handler_labels; label; label = XEXP (label, 1))
2597 for (loop_num = uid_loop_num[INSN_UID (XEXP (label, 0))];
2599 loop_num = loop_outer_loop[loop_num])
2600 loop_invalid[loop_num] = 1;
2603 /* Now scan all insn's in the function. If any JUMP_INSN branches into a
2604 loop that it is not contained within, that loop is marked invalid.
2605 If any INSN or CALL_INSN uses a label's address, then the loop containing
2606 that label is marked invalid, because it could be jumped into from
2609 Also look for blocks of code ending in an unconditional branch that
2610 exits the loop. If such a block is surrounded by a conditional
2611 branch around the block, move the block elsewhere (see below) and
2612 invert the jump to point to the code block. This may eliminate a
2613 label in our loop and will simplify processing by both us and a
2614 possible second cse pass. */
2616 for (insn = f; insn; insn = NEXT_INSN (insn))
2617 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
2619 int this_loop_num = uid_loop_num[INSN_UID (insn)];
2621 if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN)
2623 rtx note = find_reg_note (insn, REG_LABEL, NULL_RTX);
2628 for (loop_num = uid_loop_num[INSN_UID (XEXP (note, 0))];
2630 loop_num = loop_outer_loop[loop_num])
2631 loop_invalid[loop_num] = 1;
2635 if (GET_CODE (insn) != JUMP_INSN)
2638 mark_loop_jump (PATTERN (insn), this_loop_num);
2640 /* See if this is an unconditional branch outside the loop. */
2641 if (this_loop_num != -1
2642 && (GET_CODE (PATTERN (insn)) == RETURN
2643 || (simplejump_p (insn)
2644 && (uid_loop_num[INSN_UID (JUMP_LABEL (insn))]
2646 && get_max_uid () < max_uid_for_loop)
2649 rtx our_next = next_real_insn (insn);
2651 int outer_loop = -1;
2653 /* Go backwards until we reach the start of the loop, a label,
2655 for (p = PREV_INSN (insn);
2656 GET_CODE (p) != CODE_LABEL
2657 && ! (GET_CODE (p) == NOTE
2658 && NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
2659 && GET_CODE (p) != JUMP_INSN;
2663 /* Check for the case where we have a jump to an inner nested
2664 loop, and do not perform the optimization in that case. */
2666 if (JUMP_LABEL (insn))
2668 dest_loop = uid_loop_num[INSN_UID (JUMP_LABEL (insn))];
2669 if (dest_loop != -1)
2671 for (outer_loop = dest_loop; outer_loop != -1;
2672 outer_loop = loop_outer_loop[outer_loop])
2673 if (outer_loop == this_loop_num)
2678 /* Make sure that the target of P is within the current loop. */
2680 if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p)
2681 && uid_loop_num[INSN_UID (JUMP_LABEL (p))] != this_loop_num)
2682 outer_loop = this_loop_num;
2684 /* If we stopped on a JUMP_INSN to the next insn after INSN,
2685 we have a block of code to try to move.
2687 We look backward and then forward from the target of INSN
2688 to find a BARRIER at the same loop depth as the target.
2689 If we find such a BARRIER, we make a new label for the start
2690 of the block, invert the jump in P and point it to that label,
2691 and move the block of code to the spot we found. */
2693 if (outer_loop == -1
2694 && GET_CODE (p) == JUMP_INSN
2695 && JUMP_LABEL (p) != 0
2696 /* Just ignore jumps to labels that were never emitted.
2697 These always indicate compilation errors. */
2698 && INSN_UID (JUMP_LABEL (p)) != 0
2700 && ! simplejump_p (p)
2701 && next_real_insn (JUMP_LABEL (p)) == our_next)
2704 = JUMP_LABEL (insn) ? JUMP_LABEL (insn) : get_last_insn ();
2705 int target_loop_num = uid_loop_num[INSN_UID (target)];
2708 for (loc = target; loc; loc = PREV_INSN (loc))
2709 if (GET_CODE (loc) == BARRIER
2710 && uid_loop_num[INSN_UID (loc)] == target_loop_num)
2714 for (loc = target; loc; loc = NEXT_INSN (loc))
2715 if (GET_CODE (loc) == BARRIER
2716 && uid_loop_num[INSN_UID (loc)] == target_loop_num)
2721 rtx cond_label = JUMP_LABEL (p);
2722 rtx new_label = get_label_after (p);
2724 /* Ensure our label doesn't go away. */
2725 LABEL_NUSES (cond_label)++;
2727 /* Verify that uid_loop_num is large enough and that
2729 if (invert_jump (p, new_label))
2733 /* If no suitable BARRIER was found, create a suitable
2734 one before TARGET. Since TARGET is a fall through
2735 path, we'll need to insert an jump around our block
2736 and a add a BARRIER before TARGET.
2738 This creates an extra unconditional jump outside
2739 the loop. However, the benefits of removing rarely
2740 executed instructions from inside the loop usually
2741 outweighs the cost of the extra unconditional jump
2742 outside the loop. */
2747 temp = gen_jump (JUMP_LABEL (insn));
2748 temp = emit_jump_insn_before (temp, target);
2749 JUMP_LABEL (temp) = JUMP_LABEL (insn);
2750 LABEL_NUSES (JUMP_LABEL (insn))++;
2751 loc = emit_barrier_before (target);
2754 /* Include the BARRIER after INSN and copy the
2756 new_label = squeeze_notes (new_label, NEXT_INSN (insn));
2757 reorder_insns (new_label, NEXT_INSN (insn), loc);
2759 /* All those insns are now in TARGET_LOOP_NUM. */
2760 for (q = new_label; q != NEXT_INSN (NEXT_INSN (insn));
2762 uid_loop_num[INSN_UID (q)] = target_loop_num;
2764 /* The label jumped to by INSN is no longer a loop exit.
2765 Unless INSN does not have a label (e.g., it is a
2766 RETURN insn), search loop_number_exit_labels to find
2767 its label_ref, and remove it. Also turn off
2768 LABEL_OUTSIDE_LOOP_P bit. */
2769 if (JUMP_LABEL (insn))
2774 r = loop_number_exit_labels[this_loop_num];
2775 r; q = r, r = LABEL_NEXTREF (r))
2776 if (XEXP (r, 0) == JUMP_LABEL (insn))
2778 LABEL_OUTSIDE_LOOP_P (r) = 0;
2780 LABEL_NEXTREF (q) = LABEL_NEXTREF (r);
2782 loop_number_exit_labels[this_loop_num]
2783 = LABEL_NEXTREF (r);
2787 for (loop_num = this_loop_num;
2788 loop_num != -1 && loop_num != target_loop_num;
2789 loop_num = loop_outer_loop[loop_num])
2790 loop_number_exit_count[loop_num]--;
2792 /* If we didn't find it, then something is wrong. */
2797 /* P is now a jump outside the loop, so it must be put
2798 in loop_number_exit_labels, and marked as such.
2799 The easiest way to do this is to just call
2800 mark_loop_jump again for P. */
2801 mark_loop_jump (PATTERN (p), this_loop_num);
2803 /* If INSN now jumps to the insn after it,
2805 if (JUMP_LABEL (insn) != 0
2806 && (next_real_insn (JUMP_LABEL (insn))
2807 == next_real_insn (insn)))
2811 /* Continue the loop after where the conditional
2812 branch used to jump, since the only branch insn
2813 in the block (if it still remains) is an inter-loop
2814 branch and hence needs no processing. */
2815 insn = NEXT_INSN (cond_label);
2817 if (--LABEL_NUSES (cond_label) == 0)
2818 delete_insn (cond_label);
2820 /* This loop will be continued with NEXT_INSN (insn). */
2821 insn = PREV_INSN (insn);
2828 /* If any label in X jumps to a loop different from LOOP_NUM and any of the
2829 loops it is contained in, mark the target loop invalid.
2831 For speed, we assume that X is part of a pattern of a JUMP_INSN. */
2834 mark_loop_jump (x, loop_num)
2842 switch (GET_CODE (x))
2855 /* There could be a label reference in here. */
2856 mark_loop_jump (XEXP (x, 0), loop_num);
2862 mark_loop_jump (XEXP (x, 0), loop_num);
2863 mark_loop_jump (XEXP (x, 1), loop_num);
2868 mark_loop_jump (XEXP (x, 0), loop_num);
2872 dest_loop = uid_loop_num[INSN_UID (XEXP (x, 0))];
2874 /* Link together all labels that branch outside the loop. This
2875 is used by final_[bg]iv_value and the loop unrolling code. Also
2876 mark this LABEL_REF so we know that this branch should predict
2879 /* A check to make sure the label is not in an inner nested loop,
2880 since this does not count as a loop exit. */
2881 if (dest_loop != -1)
2883 for (outer_loop = dest_loop; outer_loop != -1;
2884 outer_loop = loop_outer_loop[outer_loop])
2885 if (outer_loop == loop_num)
2891 if (loop_num != -1 && outer_loop == -1)
2893 LABEL_OUTSIDE_LOOP_P (x) = 1;
2894 LABEL_NEXTREF (x) = loop_number_exit_labels[loop_num];
2895 loop_number_exit_labels[loop_num] = x;
2897 for (outer_loop = loop_num;
2898 outer_loop != -1 && outer_loop != dest_loop;
2899 outer_loop = loop_outer_loop[outer_loop])
2900 loop_number_exit_count[outer_loop]++;
2903 /* If this is inside a loop, but not in the current loop or one enclosed
2904 by it, it invalidates at least one loop. */
2906 if (dest_loop == -1)
2909 /* We must invalidate every nested loop containing the target of this
2910 label, except those that also contain the jump insn. */
2912 for (; dest_loop != -1; dest_loop = loop_outer_loop[dest_loop])
2914 /* Stop when we reach a loop that also contains the jump insn. */
2915 for (outer_loop = loop_num; outer_loop != -1;
2916 outer_loop = loop_outer_loop[outer_loop])
2917 if (dest_loop == outer_loop)
2920 /* If we get here, we know we need to invalidate a loop. */
2921 if (loop_dump_stream && ! loop_invalid[dest_loop])
2922 fprintf (loop_dump_stream,
2923 "\nLoop at %d ignored due to multiple entry points.\n",
2924 INSN_UID (loop_number_loop_starts[dest_loop]));
2926 loop_invalid[dest_loop] = 1;
2931 /* If this is not setting pc, ignore. */
2932 if (SET_DEST (x) == pc_rtx)
2933 mark_loop_jump (SET_SRC (x), loop_num);
2937 mark_loop_jump (XEXP (x, 1), loop_num);
2938 mark_loop_jump (XEXP (x, 2), loop_num);
2943 for (i = 0; i < XVECLEN (x, 0); i++)
2944 mark_loop_jump (XVECEXP (x, 0, i), loop_num);
2948 for (i = 0; i < XVECLEN (x, 1); i++)
2949 mark_loop_jump (XVECEXP (x, 1, i), loop_num);
2953 /* Treat anything else (such as a symbol_ref)
2954 as a branch out of this loop, but not into any loop. */
2958 #ifdef HAVE_decrement_and_branch_on_count
2959 LABEL_OUTSIDE_LOOP_P (x) = 1;
2960 LABEL_NEXTREF (x) = loop_number_exit_labels[loop_num];
2961 #endif /* HAVE_decrement_and_branch_on_count */
2963 loop_number_exit_labels[loop_num] = x;
2965 for (outer_loop = loop_num; outer_loop != -1;
2966 outer_loop = loop_outer_loop[outer_loop])
2967 loop_number_exit_count[outer_loop]++;
2973 /* Return nonzero if there is a label in the range from
2974 insn INSN to and including the insn whose luid is END
2975 INSN must have an assigned luid (i.e., it must not have
2976 been previously created by loop.c). */
2979 labels_in_range_p (insn, end)
2983 while (insn && INSN_LUID (insn) <= end)
2985 if (GET_CODE (insn) == CODE_LABEL)
2987 insn = NEXT_INSN (insn);
2993 /* Record that a memory reference X is being set. */
2996 note_addr_stored (x, y)
2998 rtx y ATTRIBUTE_UNUSED;
3002 if (x == 0 || GET_CODE (x) != MEM)
3005 /* Count number of memory writes.
3006 This affects heuristics in strength_reduce. */
3009 /* BLKmode MEM means all memory is clobbered. */
3010 if (GET_MODE (x) == BLKmode)
3011 unknown_address_altered = 1;
3013 if (unknown_address_altered)
3016 for (i = 0; i < loop_store_mems_idx; i++)
3017 if (rtx_equal_p (XEXP (loop_store_mems[i], 0), XEXP (x, 0))
3018 && MEM_IN_STRUCT_P (x) == MEM_IN_STRUCT_P (loop_store_mems[i]))
3020 /* We are storing at the same address as previously noted. Save the
3022 if (GET_MODE_SIZE (GET_MODE (x))
3023 > GET_MODE_SIZE (GET_MODE (loop_store_mems[i])))
3024 loop_store_mems[i] = x;
3028 if (i == NUM_STORES)
3029 unknown_address_altered = 1;
3031 else if (i == loop_store_mems_idx)
3032 loop_store_mems[loop_store_mems_idx++] = x;
3035 /* Return nonzero if the rtx X is invariant over the current loop.
3037 The value is 2 if we refer to something only conditionally invariant.
3039 If `unknown_address_altered' is nonzero, no memory ref is invariant.
3040 Otherwise, a memory ref is invariant if it does not conflict with
3041 anything stored in `loop_store_mems'. */
3048 register enum rtx_code code;
3050 int conditional = 0;
3054 code = GET_CODE (x);
3064 /* A LABEL_REF is normally invariant, however, if we are unrolling
3065 loops, and this label is inside the loop, then it isn't invariant.
3066 This is because each unrolled copy of the loop body will have
3067 a copy of this label. If this was invariant, then an insn loading
3068 the address of this label into a register might get moved outside
3069 the loop, and then each loop body would end up using the same label.
3071 We don't know the loop bounds here though, so just fail for all
3073 if (flag_unroll_loops)
3080 case UNSPEC_VOLATILE:
3084 /* We used to check RTX_UNCHANGING_P (x) here, but that is invalid
3085 since the reg might be set by initialization within the loop. */
3087 if ((x == frame_pointer_rtx || x == hard_frame_pointer_rtx
3088 || x == arg_pointer_rtx)
3089 && ! current_function_has_nonlocal_goto)
3093 && REGNO (x) < FIRST_PSEUDO_REGISTER && call_used_regs[REGNO (x)])
3096 if (VARRAY_INT (n_times_set, REGNO (x)) < 0)
3099 return VARRAY_INT (n_times_set, REGNO (x)) == 0;
3102 /* Volatile memory references must be rejected. Do this before
3103 checking for read-only items, so that volatile read-only items
3104 will be rejected also. */
3105 if (MEM_VOLATILE_P (x))
3108 /* Read-only items (such as constants in a constant pool) are
3109 invariant if their address is. */
3110 if (RTX_UNCHANGING_P (x))
3113 /* If we filled the table (or had a subroutine call), any location
3114 in memory could have been clobbered. */
3115 if (unknown_address_altered)
3118 /* See if there is any dependence between a store and this load. */
3119 for (i = loop_store_mems_idx - 1; i >= 0; i--)
3120 if (true_dependence (loop_store_mems[i], VOIDmode, x, rtx_varies_p))
3123 /* It's not invalidated by a store in memory
3124 but we must still verify the address is invariant. */
3128 /* Don't mess with insns declared volatile. */
3129 if (MEM_VOLATILE_P (x))
3137 fmt = GET_RTX_FORMAT (code);
3138 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3142 int tem = invariant_p (XEXP (x, i));
3148 else if (fmt[i] == 'E')
3151 for (j = 0; j < XVECLEN (x, i); j++)
3153 int tem = invariant_p (XVECEXP (x, i, j));
3163 return 1 + conditional;
3167 /* Return nonzero if all the insns in the loop that set REG
3168 are INSN and the immediately following insns,
3169 and if each of those insns sets REG in an invariant way
3170 (not counting uses of REG in them).
3172 The value is 2 if some of these insns are only conditionally invariant.
3174 We assume that INSN itself is the first set of REG
3175 and that its source is invariant. */
3178 consec_sets_invariant_p (reg, n_sets, insn)
3182 register rtx p = insn;
3183 register int regno = REGNO (reg);
3185 /* Number of sets we have to insist on finding after INSN. */
3186 int count = n_sets - 1;
3187 int old = VARRAY_INT (n_times_set, regno);
3191 /* If N_SETS hit the limit, we can't rely on its value. */
3195 VARRAY_INT (n_times_set, regno) = 0;
3199 register enum rtx_code code;
3203 code = GET_CODE (p);
3205 /* If library call, skip to end of it. */
3206 if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
3211 && (set = single_set (p))
3212 && GET_CODE (SET_DEST (set)) == REG
3213 && REGNO (SET_DEST (set)) == regno)
3215 this = invariant_p (SET_SRC (set));
3218 else if ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX)))
3220 /* If this is a libcall, then any invariant REG_EQUAL note is OK.
3221 If this is an ordinary insn, then only CONSTANT_P REG_EQUAL
3223 this = (CONSTANT_P (XEXP (temp, 0))
3224 || (find_reg_note (p, REG_RETVAL, NULL_RTX)
3225 && invariant_p (XEXP (temp, 0))));
3232 else if (code != NOTE)
3234 VARRAY_INT (n_times_set, regno) = old;
3239 VARRAY_INT (n_times_set, regno) = old;
3240 /* If invariant_p ever returned 2, we return 2. */
3241 return 1 + (value & 2);
3245 /* I don't think this condition is sufficient to allow INSN
3246 to be moved, so we no longer test it. */
3248 /* Return 1 if all insns in the basic block of INSN and following INSN
3249 that set REG are invariant according to TABLE. */
3252 all_sets_invariant_p (reg, insn, table)
3256 register rtx p = insn;
3257 register int regno = REGNO (reg);
3261 register enum rtx_code code;
3263 code = GET_CODE (p);
3264 if (code == CODE_LABEL || code == JUMP_INSN)
3266 if (code == INSN && GET_CODE (PATTERN (p)) == SET
3267 && GET_CODE (SET_DEST (PATTERN (p))) == REG
3268 && REGNO (SET_DEST (PATTERN (p))) == regno)
3270 if (!invariant_p (SET_SRC (PATTERN (p)), table))
3277 /* Look at all uses (not sets) of registers in X. For each, if it is
3278 the single use, set USAGE[REGNO] to INSN; if there was a previous use in
3279 a different insn, set USAGE[REGNO] to const0_rtx. */
3282 find_single_use_in_loop (insn, x, usage)
3287 enum rtx_code code = GET_CODE (x);
3288 char *fmt = GET_RTX_FORMAT (code);
3292 VARRAY_RTX (usage, REGNO (x))
3293 = (VARRAY_RTX (usage, REGNO (x)) != 0
3294 && VARRAY_RTX (usage, REGNO (x)) != insn)
3295 ? const0_rtx : insn;
3297 else if (code == SET)
3299 /* Don't count SET_DEST if it is a REG; otherwise count things
3300 in SET_DEST because if a register is partially modified, it won't
3301 show up as a potential movable so we don't care how USAGE is set
3303 if (GET_CODE (SET_DEST (x)) != REG)
3304 find_single_use_in_loop (insn, SET_DEST (x), usage);
3305 find_single_use_in_loop (insn, SET_SRC (x), usage);
3308 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
3310 if (fmt[i] == 'e' && XEXP (x, i) != 0)
3311 find_single_use_in_loop (insn, XEXP (x, i), usage);
3312 else if (fmt[i] == 'E')
3313 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
3314 find_single_use_in_loop (insn, XVECEXP (x, i, j), usage);
3318 /* Count and record any set in X which is contained in INSN. Update
3319 MAY_NOT_MOVE and LAST_SET for any register set in X. */
3322 count_one_set (insn, x, may_not_move, last_set)
3324 varray_type may_not_move;
3327 if (GET_CODE (x) == CLOBBER && GET_CODE (XEXP (x, 0)) == REG)
3328 /* Don't move a reg that has an explicit clobber.
3329 It's not worth the pain to try to do it correctly. */
3330 VARRAY_CHAR (may_not_move, REGNO (XEXP (x, 0))) = 1;
3332 if (GET_CODE (x) == SET || GET_CODE (x) == CLOBBER)
3334 rtx dest = SET_DEST (x);
3335 while (GET_CODE (dest) == SUBREG
3336 || GET_CODE (dest) == ZERO_EXTRACT
3337 || GET_CODE (dest) == SIGN_EXTRACT
3338 || GET_CODE (dest) == STRICT_LOW_PART)
3339 dest = XEXP (dest, 0);
3340 if (GET_CODE (dest) == REG)
3342 register int regno = REGNO (dest);
3343 /* If this is the first setting of this reg
3344 in current basic block, and it was set before,
3345 it must be set in two basic blocks, so it cannot
3346 be moved out of the loop. */
3347 if (VARRAY_INT (n_times_set, regno) > 0
3348 && last_set[regno] == 0)
3349 VARRAY_CHAR (may_not_move, regno) = 1;
3350 /* If this is not first setting in current basic block,
3351 see if reg was used in between previous one and this.
3352 If so, neither one can be moved. */
3353 if (last_set[regno] != 0
3354 && reg_used_between_p (dest, last_set[regno], insn))
3355 VARRAY_CHAR (may_not_move, regno) = 1;
3356 if (VARRAY_INT (n_times_set, regno) < 127)
3357 ++VARRAY_INT (n_times_set, regno);
3358 last_set[regno] = insn;
3363 /* Increment N_TIMES_SET at the index of each register
3364 that is modified by an insn between FROM and TO.
3365 If the value of an element of N_TIMES_SET becomes 127 or more,
3366 stop incrementing it, to avoid overflow.
3368 Store in SINGLE_USAGE[I] the single insn in which register I is
3369 used, if it is only used once. Otherwise, it is set to 0 (for no
3370 uses) or const0_rtx for more than one use. This parameter may be zero,
3371 in which case this processing is not done.
3373 Store in *COUNT_PTR the number of actual instruction
3374 in the loop. We use this to decide what is worth moving out. */
3376 /* last_set[n] is nonzero iff reg n has been set in the current basic block.
3377 In that case, it is the insn that last set reg n. */
3380 count_loop_regs_set (from, to, may_not_move, single_usage, count_ptr, nregs)
3381 register rtx from, to;
3382 varray_type may_not_move;
3383 varray_type single_usage;
3387 register rtx *last_set = (rtx *) alloca (nregs * sizeof (rtx));
3389 register int count = 0;
3391 bzero ((char *) last_set, nregs * sizeof (rtx));
3392 for (insn = from; insn != to; insn = NEXT_INSN (insn))
3394 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
3398 /* If requested, record registers that have exactly one use. */
3401 find_single_use_in_loop (insn, PATTERN (insn), single_usage);
3403 /* Include uses in REG_EQUAL notes. */
3404 if (REG_NOTES (insn))
3405 find_single_use_in_loop (insn, REG_NOTES (insn), single_usage);
3408 if (GET_CODE (PATTERN (insn)) == SET
3409 || GET_CODE (PATTERN (insn)) == CLOBBER)
3410 count_one_set (insn, PATTERN (insn), may_not_move, last_set);
3411 else if (GET_CODE (PATTERN (insn)) == PARALLEL)
3414 for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
3415 count_one_set (insn, XVECEXP (PATTERN (insn), 0, i),
3416 may_not_move, last_set);
3420 if (GET_CODE (insn) == CODE_LABEL || GET_CODE (insn) == JUMP_INSN)
3421 bzero ((char *) last_set, nregs * sizeof (rtx));
3426 /* Given a loop that is bounded by LOOP_START and LOOP_END
3427 and that is entered at SCAN_START,
3428 return 1 if the register set in SET contained in insn INSN is used by
3429 any insn that precedes INSN in cyclic order starting
3430 from the loop entry point.
3432 We don't want to use INSN_LUID here because if we restrict INSN to those
3433 that have a valid INSN_LUID, it means we cannot move an invariant out
3434 from an inner loop past two loops. */
3437 loop_reg_used_before_p (set, insn, loop_start, scan_start, loop_end)
3438 rtx set, insn, loop_start, scan_start, loop_end;
3440 rtx reg = SET_DEST (set);
3443 /* Scan forward checking for register usage. If we hit INSN, we
3444 are done. Otherwise, if we hit LOOP_END, wrap around to LOOP_START. */
3445 for (p = scan_start; p != insn; p = NEXT_INSN (p))
3447 if (GET_RTX_CLASS (GET_CODE (p)) == 'i'
3448 && reg_overlap_mentioned_p (reg, PATTERN (p)))
3458 /* A "basic induction variable" or biv is a pseudo reg that is set
3459 (within this loop) only by incrementing or decrementing it. */
3460 /* A "general induction variable" or giv is a pseudo reg whose
3461 value is a linear function of a biv. */
3463 /* Bivs are recognized by `basic_induction_var';
3464 Givs by `general_induction_var'. */
3466 /* Indexed by register number, indicates whether or not register is an
3467 induction variable, and if so what type. */
3469 enum iv_mode *reg_iv_type;
3471 /* Indexed by register number, contains pointer to `struct induction'
3472 if register is an induction variable. This holds general info for
3473 all induction variables. */
3475 struct induction **reg_iv_info;
3477 /* Indexed by register number, contains pointer to `struct iv_class'
3478 if register is a basic induction variable. This holds info describing
3479 the class (a related group) of induction variables that the biv belongs
3482 struct iv_class **reg_biv_class;
3484 /* The head of a list which links together (via the next field)
3485 every iv class for the current loop. */
3487 struct iv_class *loop_iv_list;
3489 /* Communication with routines called via `note_stores'. */
3491 static rtx note_insn;
3493 /* Dummy register to have non-zero DEST_REG for DEST_ADDR type givs. */
3495 static rtx addr_placeholder;
3497 /* ??? Unfinished optimizations, and possible future optimizations,
3498 for the strength reduction code. */
3500 /* ??? The interaction of biv elimination, and recognition of 'constant'
3501 bivs, may cause problems. */
3503 /* ??? Add heuristics so that DEST_ADDR strength reduction does not cause
3504 performance problems.
3506 Perhaps don't eliminate things that can be combined with an addressing
3507 mode. Find all givs that have the same biv, mult_val, and add_val;
3508 then for each giv, check to see if its only use dies in a following
3509 memory address. If so, generate a new memory address and check to see
3510 if it is valid. If it is valid, then store the modified memory address,
3511 otherwise, mark the giv as not done so that it will get its own iv. */
3513 /* ??? Could try to optimize branches when it is known that a biv is always
3516 /* ??? When replace a biv in a compare insn, we should replace with closest
3517 giv so that an optimized branch can still be recognized by the combiner,
3518 e.g. the VAX acb insn. */
3520 /* ??? Many of the checks involving uid_luid could be simplified if regscan
3521 was rerun in loop_optimize whenever a register was added or moved.
3522 Also, some of the optimizations could be a little less conservative. */
3524 /* Perform strength reduction and induction variable elimination.
3526 Pseudo registers created during this function will be beyond the last
3527 valid index in several tables including n_times_set and regno_last_uid.
3528 This does not cause a problem here, because the added registers cannot be
3529 givs outside of their loop, and hence will never be reconsidered.
3530 But scan_loop must check regnos to make sure they are in bounds.
3532 SCAN_START is the first instruction in the loop, as the loop would
3533 actually be executed. END is the NOTE_INSN_LOOP_END. LOOP_TOP is
3534 the first instruction in the loop, as it is layed out in the
3535 instruction stream. LOOP_START is the NOTE_INSN_LOOP_BEG. */
3538 strength_reduce (scan_start, end, loop_top, insn_count,
3539 loop_start, loop_end, unroll_p, bct_p)
3546 int unroll_p, bct_p ATTRIBUTE_UNUSED;
3553 /* This is 1 if current insn is not executed at least once for every loop
3555 int not_every_iteration = 0;
3556 /* This is 1 if current insn may be executed more than once for every
3558 int maybe_multiple = 0;
3559 /* Temporary list pointers for traversing loop_iv_list. */
3560 struct iv_class *bl, **backbl;
3561 /* Ratio of extra register life span we can justify
3562 for saving an instruction. More if loop doesn't call subroutines
3563 since in that case saving an insn makes more difference
3564 and more registers are available. */
3565 /* ??? could set this to last value of threshold in move_movables */
3566 int threshold = (loop_has_call ? 1 : 2) * (3 + n_non_fixed_regs);
3567 /* Map of pseudo-register replacements. */
3571 rtx end_insert_before;
3574 reg_iv_type = (enum iv_mode *) alloca (max_reg_before_loop
3575 * sizeof (enum iv_mode));
3576 bzero ((char *) reg_iv_type, max_reg_before_loop * sizeof (enum iv_mode));
3577 reg_iv_info = (struct induction **)
3578 alloca (max_reg_before_loop * sizeof (struct induction *));
3579 bzero ((char *) reg_iv_info, (max_reg_before_loop
3580 * sizeof (struct induction *)));
3581 reg_biv_class = (struct iv_class **)
3582 alloca (max_reg_before_loop * sizeof (struct iv_class *));
3583 bzero ((char *) reg_biv_class, (max_reg_before_loop
3584 * sizeof (struct iv_class *)));
3587 addr_placeholder = gen_reg_rtx (Pmode);
3589 /* Save insn immediately after the loop_end. Insns inserted after loop_end
3590 must be put before this insn, so that they will appear in the right
3591 order (i.e. loop order).
3593 If loop_end is the end of the current function, then emit a
3594 NOTE_INSN_DELETED after loop_end and set end_insert_before to the
3596 if (NEXT_INSN (loop_end) != 0)
3597 end_insert_before = NEXT_INSN (loop_end);
3599 end_insert_before = emit_note_after (NOTE_INSN_DELETED, loop_end);
3601 /* Scan through loop to find all possible bivs. */
3603 for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
3605 p = next_insn_in_loop (p, scan_start, end, loop_top))
3607 if (GET_CODE (p) == INSN
3608 && (set = single_set (p))
3609 && GET_CODE (SET_DEST (set)) == REG)
3611 dest_reg = SET_DEST (set);
3612 if (REGNO (dest_reg) < max_reg_before_loop
3613 && REGNO (dest_reg) >= FIRST_PSEUDO_REGISTER
3614 && reg_iv_type[REGNO (dest_reg)] != NOT_BASIC_INDUCT)
3616 if (basic_induction_var (SET_SRC (set), GET_MODE (SET_SRC (set)),
3617 dest_reg, p, &inc_val, &mult_val))
3619 /* It is a possible basic induction variable.
3620 Create and initialize an induction structure for it. */
3623 = (struct induction *) alloca (sizeof (struct induction));
3625 record_biv (v, p, dest_reg, inc_val, mult_val,
3626 not_every_iteration, maybe_multiple);
3627 reg_iv_type[REGNO (dest_reg)] = BASIC_INDUCT;
3629 else if (REGNO (dest_reg) < max_reg_before_loop)
3630 reg_iv_type[REGNO (dest_reg)] = NOT_BASIC_INDUCT;
3634 /* Past CODE_LABEL, we get to insns that may be executed multiple
3635 times. The only way we can be sure that they can't is if every
3636 jump insn between here and the end of the loop either
3637 returns, exits the loop, is a forward jump, or is a jump
3638 to the loop start. */
3640 if (GET_CODE (p) == CODE_LABEL)
3648 insn = NEXT_INSN (insn);
3649 if (insn == scan_start)
3657 if (insn == scan_start)
3661 if (GET_CODE (insn) == JUMP_INSN
3662 && GET_CODE (PATTERN (insn)) != RETURN
3663 && (! condjump_p (insn)
3664 || (JUMP_LABEL (insn) != 0
3665 && JUMP_LABEL (insn) != scan_start
3666 && (INSN_UID (JUMP_LABEL (insn)) >= max_uid_for_loop
3667 || INSN_UID (insn) >= max_uid_for_loop
3668 || (INSN_LUID (JUMP_LABEL (insn))
3669 < INSN_LUID (insn))))))
3677 /* Past a jump, we get to insns for which we can't count
3678 on whether they will be executed during each iteration. */
3679 /* This code appears twice in strength_reduce. There is also similar
3680 code in scan_loop. */
3681 if (GET_CODE (p) == JUMP_INSN
3682 /* If we enter the loop in the middle, and scan around to the
3683 beginning, don't set not_every_iteration for that.
3684 This can be any kind of jump, since we want to know if insns
3685 will be executed if the loop is executed. */
3686 && ! (JUMP_LABEL (p) == loop_top
3687 && ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p))
3688 || (NEXT_INSN (p) == loop_end && condjump_p (p)))))
3692 /* If this is a jump outside the loop, then it also doesn't
3693 matter. Check to see if the target of this branch is on the
3694 loop_number_exits_labels list. */
3696 for (label = loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]];
3698 label = LABEL_NEXTREF (label))
3699 if (XEXP (label, 0) == JUMP_LABEL (p))
3703 not_every_iteration = 1;
3706 else if (GET_CODE (p) == NOTE)
3708 /* At the virtual top of a converted loop, insns are again known to
3709 be executed each iteration: logically, the loop begins here
3710 even though the exit code has been duplicated. */
3711 if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0)
3712 not_every_iteration = 0;
3713 else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
3715 else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
3719 /* Unlike in the code motion pass where MAYBE_NEVER indicates that
3720 an insn may never be executed, NOT_EVERY_ITERATION indicates whether
3721 or not an insn is known to be executed each iteration of the
3722 loop, whether or not any iterations are known to occur.
3724 Therefore, if we have just passed a label and have no more labels
3725 between here and the test insn of the loop, we know these insns
3726 will be executed each iteration. */
3728 if (not_every_iteration && GET_CODE (p) == CODE_LABEL
3729 && no_labels_between_p (p, loop_end))
3730 not_every_iteration = 0;
3733 /* Scan loop_iv_list to remove all regs that proved not to be bivs.
3734 Make a sanity check against n_times_set. */
3735 for (backbl = &loop_iv_list, bl = *backbl; bl; bl = bl->next)
3737 if (reg_iv_type[bl->regno] != BASIC_INDUCT
3738 /* Above happens if register modified by subreg, etc. */
3739 /* Make sure it is not recognized as a basic induction var: */
3740 || VARRAY_INT (n_times_set, bl->regno) != bl->biv_count
3741 /* If never incremented, it is invariant that we decided not to
3742 move. So leave it alone. */
3743 || ! bl->incremented)
3745 if (loop_dump_stream)
3746 fprintf (loop_dump_stream, "Reg %d: biv discarded, %s\n",
3748 (reg_iv_type[bl->regno] != BASIC_INDUCT
3749 ? "not induction variable"
3750 : (! bl->incremented ? "never incremented"
3753 reg_iv_type[bl->regno] = NOT_BASIC_INDUCT;
3760 if (loop_dump_stream)
3761 fprintf (loop_dump_stream, "Reg %d: biv verified\n", bl->regno);
3765 /* Exit if there are no bivs. */
3768 /* Can still unroll the loop anyways, but indicate that there is no
3769 strength reduction info available. */
3771 unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 0);
3776 /* Find initial value for each biv by searching backwards from loop_start,
3777 halting at first label. Also record any test condition. */
3780 for (p = loop_start; p && GET_CODE (p) != CODE_LABEL; p = PREV_INSN (p))
3784 if (GET_CODE (p) == CALL_INSN)
3787 if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
3788 || GET_CODE (p) == CALL_INSN)
3789 note_stores (PATTERN (p), record_initial);
3791 /* Record any test of a biv that branches around the loop if no store
3792 between it and the start of loop. We only care about tests with
3793 constants and registers and only certain of those. */
3794 if (GET_CODE (p) == JUMP_INSN
3795 && JUMP_LABEL (p) != 0
3796 && next_real_insn (JUMP_LABEL (p)) == next_real_insn (loop_end)
3797 && (test = get_condition_for_loop (p)) != 0
3798 && GET_CODE (XEXP (test, 0)) == REG
3799 && REGNO (XEXP (test, 0)) < max_reg_before_loop
3800 && (bl = reg_biv_class[REGNO (XEXP (test, 0))]) != 0
3801 && valid_initial_value_p (XEXP (test, 1), p, call_seen, loop_start)
3802 && bl->init_insn == 0)
3804 /* If an NE test, we have an initial value! */
3805 if (GET_CODE (test) == NE)
3808 bl->init_set = gen_rtx_SET (VOIDmode,
3809 XEXP (test, 0), XEXP (test, 1));
3812 bl->initial_test = test;
3816 /* Look at the each biv and see if we can say anything better about its
3817 initial value from any initializing insns set up above. (This is done
3818 in two passes to avoid missing SETs in a PARALLEL.) */
3819 for (bl = loop_iv_list; bl; bl = bl->next)
3824 if (! bl->init_insn)
3827 /* IF INIT_INSN has a REG_EQUAL or REG_EQUIV note and the value
3828 is a constant, use the value of that. */
3829 if (((note = find_reg_note (bl->init_insn, REG_EQUAL, 0)) != NULL
3830 && CONSTANT_P (XEXP (note, 0)))
3831 || ((note = find_reg_note (bl->init_insn, REG_EQUIV, 0)) != NULL
3832 && CONSTANT_P (XEXP (note, 0))))
3833 src = XEXP (note, 0);
3835 src = SET_SRC (bl->init_set);
3837 if (loop_dump_stream)
3838 fprintf (loop_dump_stream,
3839 "Biv %d initialized at insn %d: initial value ",
3840 bl->regno, INSN_UID (bl->init_insn));
3842 if ((GET_MODE (src) == GET_MODE (regno_reg_rtx[bl->regno])
3843 || GET_MODE (src) == VOIDmode)
3844 && valid_initial_value_p (src, bl->init_insn, call_seen, loop_start))
3846 bl->initial_value = src;
3848 if (loop_dump_stream)
3850 if (GET_CODE (src) == CONST_INT)
3852 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (src));
3853 fputc ('\n', loop_dump_stream);
3857 print_rtl (loop_dump_stream, src);
3858 fprintf (loop_dump_stream, "\n");
3864 /* Biv initial value is not simple move,
3865 so let it keep initial value of "itself". */
3867 if (loop_dump_stream)
3868 fprintf (loop_dump_stream, "is complex\n");
3872 /* Search the loop for general induction variables. */
3874 /* A register is a giv if: it is only set once, it is a function of a
3875 biv and a constant (or invariant), and it is not a biv. */
3877 not_every_iteration = 0;
3883 /* At end of a straight-in loop, we are done.
3884 At end of a loop entered at the bottom, scan the top. */
3885 if (p == scan_start)
3893 if (p == scan_start)
3897 /* Look for a general induction variable in a register. */
3898 if (GET_CODE (p) == INSN
3899 && (set = single_set (p))
3900 && GET_CODE (SET_DEST (set)) == REG
3901 && ! VARRAY_CHAR (may_not_optimize, REGNO (SET_DEST (set))))
3909 dest_reg = SET_DEST (set);
3910 if (REGNO (dest_reg) < FIRST_PSEUDO_REGISTER)
3913 if (/* SET_SRC is a giv. */
3914 (general_induction_var (SET_SRC (set), &src_reg, &add_val,
3915 &mult_val, 0, &benefit)
3916 /* Equivalent expression is a giv. */
3917 || ((regnote = find_reg_note (p, REG_EQUAL, NULL_RTX))
3918 && general_induction_var (XEXP (regnote, 0), &src_reg,
3919 &add_val, &mult_val, 0,
3921 /* Don't try to handle any regs made by loop optimization.
3922 We have nothing on them in regno_first_uid, etc. */
3923 && REGNO (dest_reg) < max_reg_before_loop
3924 /* Don't recognize a BASIC_INDUCT_VAR here. */
3925 && dest_reg != src_reg
3926 /* This must be the only place where the register is set. */
3927 && (VARRAY_INT (n_times_set, REGNO (dest_reg)) == 1
3928 /* or all sets must be consecutive and make a giv. */
3929 || (benefit = consec_sets_giv (benefit, p,
3931 &add_val, &mult_val))))
3935 = (struct induction *) alloca (sizeof (struct induction));
3938 /* If this is a library call, increase benefit. */
3939 if (find_reg_note (p, REG_RETVAL, NULL_RTX))
3940 benefit += libcall_benefit (p);
3942 /* Skip the consecutive insns, if there are any. */
3943 for (count = VARRAY_INT (n_times_set, REGNO (dest_reg)) - 1;
3946 /* If first insn of libcall sequence, skip to end.
3947 Do this at start of loop, since INSN is guaranteed to
3949 if (GET_CODE (p) != NOTE
3950 && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
3953 do p = NEXT_INSN (p);
3954 while (GET_CODE (p) == NOTE);
3957 record_giv (v, p, src_reg, dest_reg, mult_val, add_val, benefit,
3958 DEST_REG, not_every_iteration, NULL_PTR, loop_start,
3964 #ifndef DONT_REDUCE_ADDR
3965 /* Look for givs which are memory addresses. */
3966 /* This resulted in worse code on a VAX 8600. I wonder if it
3968 if (GET_CODE (p) == INSN)
3969 find_mem_givs (PATTERN (p), p, not_every_iteration, loop_start,
3973 /* Update the status of whether giv can derive other givs. This can
3974 change when we pass a label or an insn that updates a biv. */
3975 if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
3976 || GET_CODE (p) == CODE_LABEL)
3977 update_giv_derive (p);
3979 /* Past a jump, we get to insns for which we can't count
3980 on whether they will be executed during each iteration. */
3981 /* This code appears twice in strength_reduce. There is also similar
3982 code in scan_loop. */
3983 if (GET_CODE (p) == JUMP_INSN
3984 /* If we enter the loop in the middle, and scan around to the
3985 beginning, don't set not_every_iteration for that.
3986 This can be any kind of jump, since we want to know if insns
3987 will be executed if the loop is executed. */
3988 && ! (JUMP_LABEL (p) == loop_top
3989 && ((NEXT_INSN (NEXT_INSN (p)) == loop_end && simplejump_p (p))
3990 || (NEXT_INSN (p) == loop_end && condjump_p (p)))))
3994 /* If this is a jump outside the loop, then it also doesn't
3995 matter. Check to see if the target of this branch is on the
3996 loop_number_exits_labels list. */
3998 for (label = loop_number_exit_labels[uid_loop_num[INSN_UID (loop_start)]];
4000 label = LABEL_NEXTREF (label))
4001 if (XEXP (label, 0) == JUMP_LABEL (p))
4005 not_every_iteration = 1;
4008 else if (GET_CODE (p) == NOTE)
4010 /* At the virtual top of a converted loop, insns are again known to
4011 be executed each iteration: logically, the loop begins here
4012 even though the exit code has been duplicated. */
4013 if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_VTOP && loop_depth == 0)
4014 not_every_iteration = 0;
4015 else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_BEG)
4017 else if (NOTE_LINE_NUMBER (p) == NOTE_INSN_LOOP_END)
4021 /* Unlike in the code motion pass where MAYBE_NEVER indicates that
4022 an insn may never be executed, NOT_EVERY_ITERATION indicates whether
4023 or not an insn is known to be executed each iteration of the
4024 loop, whether or not any iterations are known to occur.
4026 Therefore, if we have just passed a label and have no more labels
4027 between here and the test insn of the loop, we know these insns
4028 will be executed each iteration. */
4030 if (not_every_iteration && GET_CODE (p) == CODE_LABEL
4031 && no_labels_between_p (p, loop_end))
4032 not_every_iteration = 0;
4035 /* Try to calculate and save the number of loop iterations. This is
4036 set to zero if the actual number can not be calculated. This must
4037 be called after all giv's have been identified, since otherwise it may
4038 fail if the iteration variable is a giv. */
4040 loop_n_iterations = loop_iterations (loop_start, loop_end);
4042 /* Now for each giv for which we still don't know whether or not it is
4043 replaceable, check to see if it is replaceable because its final value
4044 can be calculated. This must be done after loop_iterations is called,
4045 so that final_giv_value will work correctly. */
4047 for (bl = loop_iv_list; bl; bl = bl->next)
4049 struct induction *v;
4051 for (v = bl->giv; v; v = v->next_iv)
4052 if (! v->replaceable && ! v->not_replaceable)
4053 check_final_value (v, loop_start, loop_end);
4056 /* Try to prove that the loop counter variable (if any) is always
4057 nonnegative; if so, record that fact with a REG_NONNEG note
4058 so that "decrement and branch until zero" insn can be used. */
4059 check_dbra_loop (loop_end, insn_count, loop_start);
4061 /* Create reg_map to hold substitutions for replaceable giv regs. */
4062 reg_map = (rtx *) alloca (max_reg_before_loop * sizeof (rtx));
4063 bzero ((char *) reg_map, max_reg_before_loop * sizeof (rtx));
4065 /* Examine each iv class for feasibility of strength reduction/induction
4066 variable elimination. */
4068 for (bl = loop_iv_list; bl; bl = bl->next)
4070 struct induction *v;
4073 rtx final_value = 0;
4075 /* Test whether it will be possible to eliminate this biv
4076 provided all givs are reduced. This is possible if either
4077 the reg is not used outside the loop, or we can compute
4078 what its final value will be.
4080 For architectures with a decrement_and_branch_until_zero insn,
4081 don't do this if we put a REG_NONNEG note on the endtest for
4084 /* Compare against bl->init_insn rather than loop_start.
4085 We aren't concerned with any uses of the biv between
4086 init_insn and loop_start since these won't be affected
4087 by the value of the biv elsewhere in the function, so
4088 long as init_insn doesn't use the biv itself.
4089 March 14, 1989 -- self@bayes.arc.nasa.gov */
4091 if ((uid_luid[REGNO_LAST_UID (bl->regno)] < INSN_LUID (loop_end)
4093 && INSN_UID (bl->init_insn) < max_uid_for_loop
4094 && uid_luid[REGNO_FIRST_UID (bl->regno)] >= INSN_LUID (bl->init_insn)
4095 #ifdef HAVE_decrement_and_branch_until_zero
4098 && ! reg_mentioned_p (bl->biv->dest_reg, SET_SRC (bl->init_set)))
4099 || ((final_value = final_biv_value (bl, loop_start, loop_end))
4100 #ifdef HAVE_decrement_and_branch_until_zero
4104 bl->eliminable = maybe_eliminate_biv (bl, loop_start, end, 0,
4105 threshold, insn_count);
4108 if (loop_dump_stream)
4110 fprintf (loop_dump_stream,
4111 "Cannot eliminate biv %d.\n",
4113 fprintf (loop_dump_stream,
4114 "First use: insn %d, last use: insn %d.\n",
4115 REGNO_FIRST_UID (bl->regno),
4116 REGNO_LAST_UID (bl->regno));
4120 /* Combine all giv's for this iv_class. */
4123 /* This will be true at the end, if all givs which depend on this
4124 biv have been strength reduced.
4125 We can't (currently) eliminate the biv unless this is so. */
4128 /* Check each giv in this class to see if we will benefit by reducing
4129 it. Skip giv's combined with others. */
4130 for (v = bl->giv; v; v = v->next_iv)
4132 struct induction *tv;
4134 if (v->ignore || v->same)
4137 benefit = v->benefit;
4139 /* Reduce benefit if not replaceable, since we will insert
4140 a move-insn to replace the insn that calculates this giv.
4141 Don't do this unless the giv is a user variable, since it
4142 will often be marked non-replaceable because of the duplication
4143 of the exit code outside the loop. In such a case, the copies
4144 we insert are dead and will be deleted. So they don't have
4145 a cost. Similar situations exist. */
4146 /* ??? The new final_[bg]iv_value code does a much better job
4147 of finding replaceable giv's, and hence this code may no longer
4149 if (! v->replaceable && ! bl->eliminable
4150 && REG_USERVAR_P (v->dest_reg))
4151 benefit -= copy_cost;
4153 /* Decrease the benefit to count the add-insns that we will
4154 insert to increment the reduced reg for the giv. */
4155 benefit -= add_cost * bl->biv_count;
4157 /* Decide whether to strength-reduce this giv or to leave the code
4158 unchanged (recompute it from the biv each time it is used).
4159 This decision can be made independently for each giv. */
4162 /* Attempt to guess whether autoincrement will handle some of the
4163 new add insns; if so, increase BENEFIT (undo the subtraction of
4164 add_cost that was done above). */
4165 if (v->giv_type == DEST_ADDR
4166 && GET_CODE (v->mult_val) == CONST_INT)
4168 #if defined (HAVE_POST_INCREMENT) || defined (HAVE_PRE_INCREMENT)
4169 if (INTVAL (v->mult_val) == GET_MODE_SIZE (v->mem_mode))
4170 benefit += add_cost * bl->biv_count;
4172 #if defined (HAVE_POST_DECREMENT) || defined (HAVE_PRE_DECREMENT)
4173 if (-INTVAL (v->mult_val) == GET_MODE_SIZE (v->mem_mode))
4174 benefit += add_cost * bl->biv_count;
4179 /* If an insn is not to be strength reduced, then set its ignore
4180 flag, and clear all_reduced. */
4182 /* A giv that depends on a reversed biv must be reduced if it is
4183 used after the loop exit, otherwise, it would have the wrong
4184 value after the loop exit. To make it simple, just reduce all
4185 of such giv's whether or not we know they are used after the loop
4188 if ( ! flag_reduce_all_givs && v->lifetime * threshold * benefit < insn_count
4191 if (loop_dump_stream)
4192 fprintf (loop_dump_stream,
4193 "giv of insn %d not worth while, %d vs %d.\n",
4195 v->lifetime * threshold * benefit, insn_count);
4201 /* Check that we can increment the reduced giv without a
4202 multiply insn. If not, reject it. */
4204 for (tv = bl->biv; tv; tv = tv->next_iv)
4205 if (tv->mult_val == const1_rtx
4206 && ! product_cheap_p (tv->add_val, v->mult_val))
4208 if (loop_dump_stream)
4209 fprintf (loop_dump_stream,
4210 "giv of insn %d: would need a multiply.\n",
4211 INSN_UID (v->insn));
4219 /* Reduce each giv that we decided to reduce. */
4221 for (v = bl->giv; v; v = v->next_iv)
4223 struct induction *tv;
4224 if (! v->ignore && v->same == 0)
4226 int auto_inc_opt = 0;
4228 v->new_reg = gen_reg_rtx (v->mode);
4231 /* If the target has auto-increment addressing modes, and
4232 this is an address giv, then try to put the increment
4233 immediately after its use, so that flow can create an
4234 auto-increment addressing mode. */
4235 if (v->giv_type == DEST_ADDR && bl->biv_count == 1
4236 && bl->biv->always_executed && ! bl->biv->maybe_multiple
4237 /* We don't handle reversed biv's because bl->biv->insn
4238 does not have a valid INSN_LUID. */
4240 && v->always_executed && ! v->maybe_multiple
4241 && INSN_UID (v->insn) < max_uid_for_loop)
4243 /* If other giv's have been combined with this one, then
4244 this will work only if all uses of the other giv's occur
4245 before this giv's insn. This is difficult to check.
4247 We simplify this by looking for the common case where
4248 there is one DEST_REG giv, and this giv's insn is the
4249 last use of the dest_reg of that DEST_REG giv. If the
4250 increment occurs after the address giv, then we can
4251 perform the optimization. (Otherwise, the increment
4252 would have to go before other_giv, and we would not be
4253 able to combine it with the address giv to get an
4254 auto-inc address.) */
4255 if (v->combined_with)
4257 struct induction *other_giv = 0;
4259 for (tv = bl->giv; tv; tv = tv->next_iv)
4267 if (! tv && other_giv
4268 && REGNO (other_giv->dest_reg) < max_reg_before_loop
4269 && (REGNO_LAST_UID (REGNO (other_giv->dest_reg))
4270 == INSN_UID (v->insn))
4271 && INSN_LUID (v->insn) < INSN_LUID (bl->biv->insn))
4274 /* Check for case where increment is before the address
4275 giv. Do this test in "loop order". */
4276 else if ((INSN_LUID (v->insn) > INSN_LUID (bl->biv->insn)
4277 && (INSN_LUID (v->insn) < INSN_LUID (scan_start)
4278 || (INSN_LUID (bl->biv->insn)
4279 > INSN_LUID (scan_start))))
4280 || (INSN_LUID (v->insn) < INSN_LUID (scan_start)
4281 && (INSN_LUID (scan_start)
4282 < INSN_LUID (bl->biv->insn))))
4291 /* We can't put an insn immediately after one setting
4292 cc0, or immediately before one using cc0. */
4293 if ((auto_inc_opt == 1 && sets_cc0_p (PATTERN (v->insn)))
4294 || (auto_inc_opt == -1
4295 && (prev = prev_nonnote_insn (v->insn)) != 0
4296 && GET_RTX_CLASS (GET_CODE (prev)) == 'i'
4297 && sets_cc0_p (PATTERN (prev))))
4303 v->auto_inc_opt = 1;
4307 /* For each place where the biv is incremented, add an insn
4308 to increment the new, reduced reg for the giv. */
4309 for (tv = bl->biv; tv; tv = tv->next_iv)
4314 insert_before = tv->insn;
4315 else if (auto_inc_opt == 1)
4316 insert_before = NEXT_INSN (v->insn);
4318 insert_before = v->insn;
4320 if (tv->mult_val == const1_rtx)
4321 emit_iv_add_mult (tv->add_val, v->mult_val,
4322 v->new_reg, v->new_reg, insert_before);
4323 else /* tv->mult_val == const0_rtx */
4324 /* A multiply is acceptable here
4325 since this is presumed to be seldom executed. */
4326 emit_iv_add_mult (tv->add_val, v->mult_val,
4327 v->add_val, v->new_reg, insert_before);
4330 /* Add code at loop start to initialize giv's reduced reg. */
4332 emit_iv_add_mult (bl->initial_value, v->mult_val,
4333 v->add_val, v->new_reg, loop_start);
4337 /* Rescan all givs. If a giv is the same as a giv not reduced, mark it
4340 For each giv register that can be reduced now: if replaceable,
4341 substitute reduced reg wherever the old giv occurs;
4342 else add new move insn "giv_reg = reduced_reg".
4344 Also check for givs whose first use is their definition and whose
4345 last use is the definition of another giv. If so, it is likely
4346 dead and should not be used to eliminate a biv. */
4347 for (v = bl->giv; v; v = v->next_iv)
4349 if (v->same && v->same->ignore)
4355 if (v->giv_type == DEST_REG
4356 && REGNO_FIRST_UID (REGNO (v->dest_reg)) == INSN_UID (v->insn))
4358 struct induction *v1;
4360 for (v1 = bl->giv; v1; v1 = v1->next_iv)
4361 if (REGNO_LAST_UID (REGNO (v->dest_reg)) == INSN_UID (v1->insn))
4365 /* Update expression if this was combined, in case other giv was
4368 v->new_reg = replace_rtx (v->new_reg,
4369 v->same->dest_reg, v->same->new_reg);
4371 if (v->giv_type == DEST_ADDR)
4372 /* Store reduced reg as the address in the memref where we found
4374 validate_change (v->insn, v->location, v->new_reg, 0);
4375 else if (v->replaceable)
4377 reg_map[REGNO (v->dest_reg)] = v->new_reg;
4380 /* I can no longer duplicate the original problem. Perhaps
4381 this is unnecessary now? */
4383 /* Replaceable; it isn't strictly necessary to delete the old
4384 insn and emit a new one, because v->dest_reg is now dead.
4386 However, especially when unrolling loops, the special
4387 handling for (set REG0 REG1) in the second cse pass may
4388 make v->dest_reg live again. To avoid this problem, emit
4389 an insn to set the original giv reg from the reduced giv.
4390 We can not delete the original insn, since it may be part
4391 of a LIBCALL, and the code in flow that eliminates dead
4392 libcalls will fail if it is deleted. */
4393 emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg),
4399 /* Not replaceable; emit an insn to set the original giv reg from
4400 the reduced giv, same as above. */
4401 emit_insn_after (gen_move_insn (v->dest_reg, v->new_reg),
4405 /* When a loop is reversed, givs which depend on the reversed
4406 biv, and which are live outside the loop, must be set to their
4407 correct final value. This insn is only needed if the giv is
4408 not replaceable. The correct final value is the same as the
4409 value that the giv starts the reversed loop with. */
4410 if (bl->reversed && ! v->replaceable)
4411 emit_iv_add_mult (bl->initial_value, v->mult_val,
4412 v->add_val, v->dest_reg, end_insert_before);
4413 else if (v->final_value)
4417 /* If the loop has multiple exits, emit the insn before the
4418 loop to ensure that it will always be executed no matter
4419 how the loop exits. Otherwise, emit the insn after the loop,
4420 since this is slightly more efficient. */
4421 if (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
4422 insert_before = loop_start;
4424 insert_before = end_insert_before;
4425 emit_insn_before (gen_move_insn (v->dest_reg, v->final_value),
4429 /* If the insn to set the final value of the giv was emitted
4430 before the loop, then we must delete the insn inside the loop
4431 that sets it. If this is a LIBCALL, then we must delete
4432 every insn in the libcall. Note, however, that
4433 final_giv_value will only succeed when there are multiple
4434 exits if the giv is dead at each exit, hence it does not
4435 matter that the original insn remains because it is dead
4437 /* Delete the insn inside the loop that sets the giv since
4438 the giv is now set before (or after) the loop. */
4439 delete_insn (v->insn);
4443 if (loop_dump_stream)
4445 fprintf (loop_dump_stream, "giv at %d reduced to ",
4446 INSN_UID (v->insn));
4447 print_rtl (loop_dump_stream, v->new_reg);
4448 fprintf (loop_dump_stream, "\n");
4452 /* All the givs based on the biv bl have been reduced if they
4455 /* For each giv not marked as maybe dead that has been combined with a
4456 second giv, clear any "maybe dead" mark on that second giv.
4457 v->new_reg will either be or refer to the register of the giv it
4460 Doing this clearing avoids problems in biv elimination where a
4461 giv's new_reg is a complex value that can't be put in the insn but
4462 the giv combined with (with a reg as new_reg) is marked maybe_dead.
4463 Since the register will be used in either case, we'd prefer it be
4464 used from the simpler giv. */
4466 for (v = bl->giv; v; v = v->next_iv)
4467 if (! v->maybe_dead && v->same)
4468 v->same->maybe_dead = 0;
4470 /* Try to eliminate the biv, if it is a candidate.
4471 This won't work if ! all_reduced,
4472 since the givs we planned to use might not have been reduced.
4474 We have to be careful that we didn't initially think we could eliminate
4475 this biv because of a giv that we now think may be dead and shouldn't
4476 be used as a biv replacement.
4478 Also, there is the possibility that we may have a giv that looks
4479 like it can be used to eliminate a biv, but the resulting insn
4480 isn't valid. This can happen, for example, on the 88k, where a
4481 JUMP_INSN can compare a register only with zero. Attempts to
4482 replace it with a compare with a constant will fail.
4484 Note that in cases where this call fails, we may have replaced some
4485 of the occurrences of the biv with a giv, but no harm was done in
4486 doing so in the rare cases where it can occur. */
4488 if (all_reduced == 1 && bl->eliminable
4489 && maybe_eliminate_biv (bl, loop_start, end, 1,
4490 threshold, insn_count))
4493 /* ?? If we created a new test to bypass the loop entirely,
4494 or otherwise drop straight in, based on this test, then
4495 we might want to rewrite it also. This way some later
4496 pass has more hope of removing the initialization of this
4499 /* If final_value != 0, then the biv may be used after loop end
4500 and we must emit an insn to set it just in case.
4502 Reversed bivs already have an insn after the loop setting their
4503 value, so we don't need another one. We can't calculate the
4504 proper final value for such a biv here anyways. */
4505 if (final_value != 0 && ! bl->reversed)
4509 /* If the loop has multiple exits, emit the insn before the
4510 loop to ensure that it will always be executed no matter
4511 how the loop exits. Otherwise, emit the insn after the
4512 loop, since this is slightly more efficient. */
4513 if (loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
4514 insert_before = loop_start;
4516 insert_before = end_insert_before;
4518 emit_insn_before (gen_move_insn (bl->biv->dest_reg, final_value),
4523 /* Delete all of the instructions inside the loop which set
4524 the biv, as they are all dead. If is safe to delete them,
4525 because an insn setting a biv will never be part of a libcall. */
4526 /* However, deleting them will invalidate the regno_last_uid info,
4527 so keeping them around is more convenient. Final_biv_value
4528 will only succeed when there are multiple exits if the biv
4529 is dead at each exit, hence it does not matter that the original
4530 insn remains, because it is dead anyways. */
4531 for (v = bl->biv; v; v = v->next_iv)
4532 delete_insn (v->insn);
4535 if (loop_dump_stream)
4536 fprintf (loop_dump_stream, "Reg %d: biv eliminated\n",
4541 /* Go through all the instructions in the loop, making all the
4542 register substitutions scheduled in REG_MAP. */
4544 for (p = loop_start; p != end; p = NEXT_INSN (p))
4545 if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
4546 || GET_CODE (p) == CALL_INSN)
4548 replace_regs (PATTERN (p), reg_map, max_reg_before_loop, 0);
4549 replace_regs (REG_NOTES (p), reg_map, max_reg_before_loop, 0);
4553 /* Unroll loops from within strength reduction so that we can use the
4554 induction variable information that strength_reduce has already
4558 unroll_loop (loop_end, insn_count, loop_start, end_insert_before, 1);
4560 #ifdef HAVE_decrement_and_branch_on_count
4561 /* Instrument the loop with BCT insn. */
4562 if (HAVE_decrement_and_branch_on_count && bct_p
4563 && flag_branch_on_count_reg)
4564 insert_bct (loop_start, loop_end);
4565 #endif /* HAVE_decrement_and_branch_on_count */
4567 if (loop_dump_stream)
4568 fprintf (loop_dump_stream, "\n");
4571 /* Return 1 if X is a valid source for an initial value (or as value being
4572 compared against in an initial test).
4574 X must be either a register or constant and must not be clobbered between
4575 the current insn and the start of the loop.
4577 INSN is the insn containing X. */
4580 valid_initial_value_p (x, insn, call_seen, loop_start)
4589 /* Only consider pseudos we know about initialized in insns whose luids
4591 if (GET_CODE (x) != REG
4592 || REGNO (x) >= max_reg_before_loop)
4595 /* Don't use call-clobbered registers across a call which clobbers it. On
4596 some machines, don't use any hard registers at all. */
4597 if (REGNO (x) < FIRST_PSEUDO_REGISTER
4598 && (SMALL_REGISTER_CLASSES
4599 || (call_used_regs[REGNO (x)] && call_seen)))
4602 /* Don't use registers that have been clobbered before the start of the
4604 if (reg_set_between_p (x, insn, loop_start))
4610 /* Scan X for memory refs and check each memory address
4611 as a possible giv. INSN is the insn whose pattern X comes from.
4612 NOT_EVERY_ITERATION is 1 if the insn might not be executed during
4613 every loop iteration. */
4616 find_mem_givs (x, insn, not_every_iteration, loop_start, loop_end)
4619 int not_every_iteration;
4620 rtx loop_start, loop_end;
4623 register enum rtx_code code;
4629 code = GET_CODE (x);
4653 /* This code used to disable creating GIVs with mult_val == 1 and
4654 add_val == 0. However, this leads to lost optimizations when
4655 it comes time to combine a set of related DEST_ADDR GIVs, since
4656 this one would not be seen. */
4658 if (general_induction_var (XEXP (x, 0), &src_reg, &add_val,
4659 &mult_val, 1, &benefit))
4661 /* Found one; record it. */
4663 = (struct induction *) oballoc (sizeof (struct induction));
4665 record_giv (v, insn, src_reg, addr_placeholder, mult_val,
4666 add_val, benefit, DEST_ADDR, not_every_iteration,
4667 &XEXP (x, 0), loop_start, loop_end);
4669 v->mem_mode = GET_MODE (x);
4678 /* Recursively scan the subexpressions for other mem refs. */
4680 fmt = GET_RTX_FORMAT (code);
4681 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
4683 find_mem_givs (XEXP (x, i), insn, not_every_iteration, loop_start,
4685 else if (fmt[i] == 'E')
4686 for (j = 0; j < XVECLEN (x, i); j++)
4687 find_mem_givs (XVECEXP (x, i, j), insn, not_every_iteration,
4688 loop_start, loop_end);
4691 /* Fill in the data about one biv update.
4692 V is the `struct induction' in which we record the biv. (It is
4693 allocated by the caller, with alloca.)
4694 INSN is the insn that sets it.
4695 DEST_REG is the biv's reg.
4697 MULT_VAL is const1_rtx if the biv is being incremented here, in which case
4698 INC_VAL is the increment. Otherwise, MULT_VAL is const0_rtx and the biv is
4699 being set to INC_VAL.
4701 NOT_EVERY_ITERATION is nonzero if this biv update is not know to be
4702 executed every iteration; MAYBE_MULTIPLE is nonzero if this biv update
4703 can be executed more than once per iteration. If MAYBE_MULTIPLE
4704 and NOT_EVERY_ITERATION are both zero, we know that the biv update is
4705 executed exactly once per iteration. */
4708 record_biv (v, insn, dest_reg, inc_val, mult_val,
4709 not_every_iteration, maybe_multiple)
4710 struct induction *v;
4715 int not_every_iteration;
4718 struct iv_class *bl;
4721 v->src_reg = dest_reg;
4722 v->dest_reg = dest_reg;
4723 v->mult_val = mult_val;
4724 v->add_val = inc_val;
4725 v->mode = GET_MODE (dest_reg);
4726 v->always_computable = ! not_every_iteration;
4727 v->always_executed = ! not_every_iteration;
4728 v->maybe_multiple = maybe_multiple;
4730 /* Add this to the reg's iv_class, creating a class
4731 if this is the first incrementation of the reg. */
4733 bl = reg_biv_class[REGNO (dest_reg)];
4736 /* Create and initialize new iv_class. */
4738 bl = (struct iv_class *) oballoc (sizeof (struct iv_class));
4740 bl->regno = REGNO (dest_reg);
4746 /* Set initial value to the reg itself. */
4747 bl->initial_value = dest_reg;
4748 /* We haven't seen the initializing insn yet */
4751 bl->initial_test = 0;
4752 bl->incremented = 0;
4756 bl->total_benefit = 0;
4758 /* Add this class to loop_iv_list. */
4759 bl->next = loop_iv_list;
4762 /* Put it in the array of biv register classes. */
4763 reg_biv_class[REGNO (dest_reg)] = bl;
4766 /* Update IV_CLASS entry for this biv. */
4767 v->next_iv = bl->biv;
4770 if (mult_val == const1_rtx)
4771 bl->incremented = 1;
4773 if (loop_dump_stream)
4775 fprintf (loop_dump_stream,
4776 "Insn %d: possible biv, reg %d,",
4777 INSN_UID (insn), REGNO (dest_reg));
4778 if (GET_CODE (inc_val) == CONST_INT)
4780 fprintf (loop_dump_stream, " const =");
4781 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (inc_val));
4782 fputc ('\n', loop_dump_stream);
4786 fprintf (loop_dump_stream, " const = ");
4787 print_rtl (loop_dump_stream, inc_val);
4788 fprintf (loop_dump_stream, "\n");
4793 /* Fill in the data about one giv.
4794 V is the `struct induction' in which we record the giv. (It is
4795 allocated by the caller, with alloca.)
4796 INSN is the insn that sets it.
4797 BENEFIT estimates the savings from deleting this insn.
4798 TYPE is DEST_REG or DEST_ADDR; it says whether the giv is computed
4799 into a register or is used as a memory address.
4801 SRC_REG is the biv reg which the giv is computed from.
4802 DEST_REG is the giv's reg (if the giv is stored in a reg).
4803 MULT_VAL and ADD_VAL are the coefficients used to compute the giv.
4804 LOCATION points to the place where this giv's value appears in INSN. */
4807 record_giv (v, insn, src_reg, dest_reg, mult_val, add_val, benefit,
4808 type, not_every_iteration, location, loop_start, loop_end)
4809 struct induction *v;
4813 rtx mult_val, add_val;
4816 int not_every_iteration;
4818 rtx loop_start, loop_end;
4820 struct induction *b;
4821 struct iv_class *bl;
4822 rtx set = single_set (insn);
4825 v->src_reg = src_reg;
4827 v->dest_reg = dest_reg;
4828 v->mult_val = mult_val;
4829 v->add_val = add_val;
4830 v->benefit = benefit;
4831 v->location = location;
4833 v->combined_with = 0;
4834 v->maybe_multiple = 0;
4836 v->derive_adjustment = 0;
4842 v->auto_inc_opt = 0;
4846 /* The v->always_computable field is used in update_giv_derive, to
4847 determine whether a giv can be used to derive another giv. For a
4848 DEST_REG giv, INSN computes a new value for the giv, so its value
4849 isn't computable if INSN insn't executed every iteration.
4850 However, for a DEST_ADDR giv, INSN merely uses the value of the giv;
4851 it does not compute a new value. Hence the value is always computable
4852 regardless of whether INSN is executed each iteration. */
4854 if (type == DEST_ADDR)
4855 v->always_computable = 1;
4857 v->always_computable = ! not_every_iteration;
4859 v->always_executed = ! not_every_iteration;
4861 if (type == DEST_ADDR)
4863 v->mode = GET_MODE (*location);
4867 else /* type == DEST_REG */
4869 v->mode = GET_MODE (SET_DEST (set));
4871 v->lifetime = (uid_luid[REGNO_LAST_UID (REGNO (dest_reg))]
4872 - uid_luid[REGNO_FIRST_UID (REGNO (dest_reg))]);
4874 v->times_used = VARRAY_INT (n_times_used, REGNO (dest_reg));
4876 /* If the lifetime is zero, it means that this register is
4877 really a dead store. So mark this as a giv that can be
4878 ignored. This will not prevent the biv from being eliminated. */
4879 if (v->lifetime == 0)
4882 reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT;
4883 reg_iv_info[REGNO (dest_reg)] = v;
4886 /* Add the giv to the class of givs computed from one biv. */
4888 bl = reg_biv_class[REGNO (src_reg)];
4891 v->next_iv = bl->giv;
4893 /* Don't count DEST_ADDR. This is supposed to count the number of
4894 insns that calculate givs. */
4895 if (type == DEST_REG)
4897 bl->total_benefit += benefit;
4900 /* Fatal error, biv missing for this giv? */
4903 if (type == DEST_ADDR)
4907 /* The giv can be replaced outright by the reduced register only if all
4908 of the following conditions are true:
4909 - the insn that sets the giv is always executed on any iteration
4910 on which the giv is used at all
4911 (there are two ways to deduce this:
4912 either the insn is executed on every iteration,
4913 or all uses follow that insn in the same basic block),
4914 - the giv is not used outside the loop
4915 - no assignments to the biv occur during the giv's lifetime. */
4917 if (REGNO_FIRST_UID (REGNO (dest_reg)) == INSN_UID (insn)
4918 /* Previous line always fails if INSN was moved by loop opt. */
4919 && uid_luid[REGNO_LAST_UID (REGNO (dest_reg))] < INSN_LUID (loop_end)
4920 && (! not_every_iteration
4921 || last_use_this_basic_block (dest_reg, insn)))
4923 /* Now check that there are no assignments to the biv within the
4924 giv's lifetime. This requires two separate checks. */
4926 /* Check each biv update, and fail if any are between the first
4927 and last use of the giv.
4929 If this loop contains an inner loop that was unrolled, then
4930 the insn modifying the biv may have been emitted by the loop
4931 unrolling code, and hence does not have a valid luid. Just
4932 mark the biv as not replaceable in this case. It is not very
4933 useful as a biv, because it is used in two different loops.
4934 It is very unlikely that we would be able to optimize the giv
4935 using this biv anyways. */
4938 for (b = bl->biv; b; b = b->next_iv)
4940 if (INSN_UID (b->insn) >= max_uid_for_loop
4941 || ((uid_luid[INSN_UID (b->insn)]
4942 >= uid_luid[REGNO_FIRST_UID (REGNO (dest_reg))])
4943 && (uid_luid[INSN_UID (b->insn)]
4944 <= uid_luid[REGNO_LAST_UID (REGNO (dest_reg))])))
4947 v->not_replaceable = 1;
4952 /* If there are any backwards branches that go from after the
4953 biv update to before it, then this giv is not replaceable. */
4955 for (b = bl->biv; b; b = b->next_iv)
4956 if (back_branch_in_range_p (b->insn, loop_start, loop_end))
4959 v->not_replaceable = 1;
4965 /* May still be replaceable, we don't have enough info here to
4968 v->not_replaceable = 0;
4972 /* Record whether the add_val contains a const_int, for later use by
4977 v->no_const_addval = 1;
4978 if (tem == const0_rtx)
4980 else if (GET_CODE (tem) == CONST_INT)
4981 v->no_const_addval = 0;
4982 else if (GET_CODE (tem) == PLUS)
4986 if (GET_CODE (XEXP (tem, 0)) == PLUS)
4987 tem = XEXP (tem, 0);
4988 else if (GET_CODE (XEXP (tem, 1)) == PLUS)
4989 tem = XEXP (tem, 1);
4993 if (GET_CODE (XEXP (tem, 1)) == CONST_INT)
4994 v->no_const_addval = 0;
4998 if (loop_dump_stream)
5000 if (type == DEST_REG)
5001 fprintf (loop_dump_stream, "Insn %d: giv reg %d",
5002 INSN_UID (insn), REGNO (dest_reg));
5004 fprintf (loop_dump_stream, "Insn %d: dest address",
5007 fprintf (loop_dump_stream, " src reg %d benefit %d",
5008 REGNO (src_reg), v->benefit);
5009 fprintf (loop_dump_stream, " used %d lifetime %d",
5010 v->times_used, v->lifetime);
5013 fprintf (loop_dump_stream, " replaceable");
5015 if (v->no_const_addval)
5016 fprintf (loop_dump_stream, " ncav");
5018 if (GET_CODE (mult_val) == CONST_INT)
5020 fprintf (loop_dump_stream, " mult ");
5021 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (mult_val));
5025 fprintf (loop_dump_stream, " mult ");
5026 print_rtl (loop_dump_stream, mult_val);
5029 if (GET_CODE (add_val) == CONST_INT)
5031 fprintf (loop_dump_stream, " add ");
5032 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC, INTVAL (add_val));
5036 fprintf (loop_dump_stream, " add ");
5037 print_rtl (loop_dump_stream, add_val);
5041 if (loop_dump_stream)
5042 fprintf (loop_dump_stream, "\n");
5047 /* All this does is determine whether a giv can be made replaceable because
5048 its final value can be calculated. This code can not be part of record_giv
5049 above, because final_giv_value requires that the number of loop iterations
5050 be known, and that can not be accurately calculated until after all givs
5051 have been identified. */
5054 check_final_value (v, loop_start, loop_end)
5055 struct induction *v;
5056 rtx loop_start, loop_end;
5058 struct iv_class *bl;
5059 rtx final_value = 0;
5061 bl = reg_biv_class[REGNO (v->src_reg)];
5063 /* DEST_ADDR givs will never reach here, because they are always marked
5064 replaceable above in record_giv. */
5066 /* The giv can be replaced outright by the reduced register only if all
5067 of the following conditions are true:
5068 - the insn that sets the giv is always executed on any iteration
5069 on which the giv is used at all
5070 (there are two ways to deduce this:
5071 either the insn is executed on every iteration,
5072 or all uses follow that insn in the same basic block),
5073 - its final value can be calculated (this condition is different
5074 than the one above in record_giv)
5075 - no assignments to the biv occur during the giv's lifetime. */
5078 /* This is only called now when replaceable is known to be false. */
5079 /* Clear replaceable, so that it won't confuse final_giv_value. */
5083 if ((final_value = final_giv_value (v, loop_start, loop_end))
5084 && (v->always_computable || last_use_this_basic_block (v->dest_reg, v->insn)))
5086 int biv_increment_seen = 0;
5092 /* When trying to determine whether or not a biv increment occurs
5093 during the lifetime of the giv, we can ignore uses of the variable
5094 outside the loop because final_value is true. Hence we can not
5095 use regno_last_uid and regno_first_uid as above in record_giv. */
5097 /* Search the loop to determine whether any assignments to the
5098 biv occur during the giv's lifetime. Start with the insn
5099 that sets the giv, and search around the loop until we come
5100 back to that insn again.
5102 Also fail if there is a jump within the giv's lifetime that jumps
5103 to somewhere outside the lifetime but still within the loop. This
5104 catches spaghetti code where the execution order is not linear, and
5105 hence the above test fails. Here we assume that the giv lifetime
5106 does not extend from one iteration of the loop to the next, so as
5107 to make the test easier. Since the lifetime isn't known yet,
5108 this requires two loops. See also record_giv above. */
5110 last_giv_use = v->insn;
5116 p = NEXT_INSN (loop_start);
5120 if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
5121 || GET_CODE (p) == CALL_INSN)
5123 if (biv_increment_seen)
5125 if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
5128 v->not_replaceable = 1;
5132 else if (reg_set_p (v->src_reg, PATTERN (p)))
5133 biv_increment_seen = 1;
5134 else if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
5139 /* Now that the lifetime of the giv is known, check for branches
5140 from within the lifetime to outside the lifetime if it is still
5150 p = NEXT_INSN (loop_start);
5151 if (p == last_giv_use)
5154 if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p)
5155 && LABEL_NAME (JUMP_LABEL (p))
5156 && ((INSN_UID (JUMP_LABEL (p)) >= max_uid_for_loop)
5157 || (INSN_UID (v->insn) >= max_uid_for_loop)
5158 || (INSN_UID (last_giv_use) >= max_uid_for_loop)
5159 || (INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (v->insn)
5160 && INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start))
5161 || (INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (last_giv_use)
5162 && INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end))))
5165 v->not_replaceable = 1;
5167 if (loop_dump_stream)
5168 fprintf (loop_dump_stream,
5169 "Found branch outside giv lifetime.\n");
5176 /* If it is replaceable, then save the final value. */
5178 v->final_value = final_value;
5181 if (loop_dump_stream && v->replaceable)
5182 fprintf (loop_dump_stream, "Insn %d: giv reg %d final_value replaceable\n",
5183 INSN_UID (v->insn), REGNO (v->dest_reg));
5186 /* Update the status of whether a giv can derive other givs.
5188 We need to do something special if there is or may be an update to the biv
5189 between the time the giv is defined and the time it is used to derive
5192 In addition, a giv that is only conditionally set is not allowed to
5193 derive another giv once a label has been passed.
5195 The cases we look at are when a label or an update to a biv is passed. */
5198 update_giv_derive (p)
5201 struct iv_class *bl;
5202 struct induction *biv, *giv;
5206 /* Search all IV classes, then all bivs, and finally all givs.
5208 There are three cases we are concerned with. First we have the situation
5209 of a giv that is only updated conditionally. In that case, it may not
5210 derive any givs after a label is passed.
5212 The second case is when a biv update occurs, or may occur, after the
5213 definition of a giv. For certain biv updates (see below) that are
5214 known to occur between the giv definition and use, we can adjust the
5215 giv definition. For others, or when the biv update is conditional,
5216 we must prevent the giv from deriving any other givs. There are two
5217 sub-cases within this case.
5219 If this is a label, we are concerned with any biv update that is done
5220 conditionally, since it may be done after the giv is defined followed by
5221 a branch here (actually, we need to pass both a jump and a label, but
5222 this extra tracking doesn't seem worth it).
5224 If this is a jump, we are concerned about any biv update that may be
5225 executed multiple times. We are actually only concerned about
5226 backward jumps, but it is probably not worth performing the test
5227 on the jump again here.
5229 If this is a biv update, we must adjust the giv status to show that a
5230 subsequent biv update was performed. If this adjustment cannot be done,
5231 the giv cannot derive further givs. */
5233 for (bl = loop_iv_list; bl; bl = bl->next)
5234 for (biv = bl->biv; biv; biv = biv->next_iv)
5235 if (GET_CODE (p) == CODE_LABEL || GET_CODE (p) == JUMP_INSN
5238 for (giv = bl->giv; giv; giv = giv->next_iv)
5240 /* If cant_derive is already true, there is no point in
5241 checking all of these conditions again. */
5242 if (giv->cant_derive)
5245 /* If this giv is conditionally set and we have passed a label,
5246 it cannot derive anything. */
5247 if (GET_CODE (p) == CODE_LABEL && ! giv->always_computable)
5248 giv->cant_derive = 1;
5250 /* Skip givs that have mult_val == 0, since
5251 they are really invariants. Also skip those that are
5252 replaceable, since we know their lifetime doesn't contain
5254 else if (giv->mult_val == const0_rtx || giv->replaceable)
5257 /* The only way we can allow this giv to derive another
5258 is if this is a biv increment and we can form the product
5259 of biv->add_val and giv->mult_val. In this case, we will
5260 be able to compute a compensation. */
5261 else if (biv->insn == p)
5265 if (biv->mult_val == const1_rtx)
5266 tem = simplify_giv_expr (gen_rtx_MULT (giv->mode,
5271 if (tem && giv->derive_adjustment)
5272 tem = simplify_giv_expr (gen_rtx_PLUS (giv->mode, tem,
5273 giv->derive_adjustment),
5276 giv->derive_adjustment = tem;
5278 giv->cant_derive = 1;
5280 else if ((GET_CODE (p) == CODE_LABEL && ! biv->always_computable)
5281 || (GET_CODE (p) == JUMP_INSN && biv->maybe_multiple))
5282 giv->cant_derive = 1;
5287 /* Check whether an insn is an increment legitimate for a basic induction var.
5288 X is the source of insn P, or a part of it.
5289 MODE is the mode in which X should be interpreted.
5291 DEST_REG is the putative biv, also the destination of the insn.
5292 We accept patterns of these forms:
5293 REG = REG + INVARIANT (includes REG = REG - CONSTANT)
5294 REG = INVARIANT + REG
5296 If X is suitable, we return 1, set *MULT_VAL to CONST1_RTX,
5297 and store the additive term into *INC_VAL.
5299 If X is an assignment of an invariant into DEST_REG, we set
5300 *MULT_VAL to CONST0_RTX, and store the invariant into *INC_VAL.
5302 We also want to detect a BIV when it corresponds to a variable
5303 whose mode was promoted via PROMOTED_MODE. In that case, an increment
5304 of the variable may be a PLUS that adds a SUBREG of that variable to
5305 an invariant and then sign- or zero-extends the result of the PLUS
5308 Most GIVs in such cases will be in the promoted mode, since that is the
5309 probably the natural computation mode (and almost certainly the mode
5310 used for addresses) on the machine. So we view the pseudo-reg containing
5311 the variable as the BIV, as if it were simply incremented.
5313 Note that treating the entire pseudo as a BIV will result in making
5314 simple increments to any GIVs based on it. However, if the variable
5315 overflows in its declared mode but not its promoted mode, the result will
5316 be incorrect. This is acceptable if the variable is signed, since
5317 overflows in such cases are undefined, but not if it is unsigned, since
5318 those overflows are defined. So we only check for SIGN_EXTEND and
5321 If we cannot find a biv, we return 0. */
5324 basic_induction_var (x, mode, dest_reg, p, inc_val, mult_val)
5326 enum machine_mode mode;
5332 register enum rtx_code code;
5336 code = GET_CODE (x);
5340 if (rtx_equal_p (XEXP (x, 0), dest_reg)
5341 || (GET_CODE (XEXP (x, 0)) == SUBREG
5342 && SUBREG_PROMOTED_VAR_P (XEXP (x, 0))
5343 && SUBREG_REG (XEXP (x, 0)) == dest_reg))
5345 else if (rtx_equal_p (XEXP (x, 1), dest_reg)
5346 || (GET_CODE (XEXP (x, 1)) == SUBREG
5347 && SUBREG_PROMOTED_VAR_P (XEXP (x, 1))
5348 && SUBREG_REG (XEXP (x, 1)) == dest_reg))
5353 if (invariant_p (arg) != 1)
5356 *inc_val = convert_modes (GET_MODE (dest_reg), GET_MODE (x), arg, 0);
5357 *mult_val = const1_rtx;
5361 /* If this is a SUBREG for a promoted variable, check the inner
5363 if (SUBREG_PROMOTED_VAR_P (x))
5364 return basic_induction_var (SUBREG_REG (x), GET_MODE (SUBREG_REG (x)),
5365 dest_reg, p, inc_val, mult_val);
5369 /* If this register is assigned in a previous insn, look at its
5370 source, but don't go outside the loop or past a label. */
5376 insn = PREV_INSN (insn);
5377 } while (insn && GET_CODE (insn) == NOTE
5378 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG);
5382 set = single_set (insn);
5386 if ((SET_DEST (set) == x
5387 || (GET_CODE (SET_DEST (set)) == SUBREG
5388 && (GET_MODE_SIZE (GET_MODE (SET_DEST (set)))
5390 && SUBREG_REG (SET_DEST (set)) == x))
5391 && basic_induction_var (SET_SRC (set),
5392 (GET_MODE (SET_SRC (set)) == VOIDmode
5394 : GET_MODE (SET_SRC (set))),
5399 /* ... fall through ... */
5401 /* Can accept constant setting of biv only when inside inner most loop.
5402 Otherwise, a biv of an inner loop may be incorrectly recognized
5403 as a biv of the outer loop,
5404 causing code to be moved INTO the inner loop. */
5406 if (invariant_p (x) != 1)
5411 /* convert_modes aborts if we try to convert to or from CCmode, so just
5412 exclude that case. It is very unlikely that a condition code value
5413 would be a useful iterator anyways. */
5414 if (loops_enclosed == 1
5415 && GET_MODE_CLASS (mode) != MODE_CC
5416 && GET_MODE_CLASS (GET_MODE (dest_reg)) != MODE_CC)
5418 /* Possible bug here? Perhaps we don't know the mode of X. */
5419 *inc_val = convert_modes (GET_MODE (dest_reg), mode, x, 0);
5420 *mult_val = const0_rtx;
5427 return basic_induction_var (XEXP (x, 0), GET_MODE (XEXP (x, 0)),
5428 dest_reg, p, inc_val, mult_val);
5431 /* Similar, since this can be a sign extension. */
5432 for (insn = PREV_INSN (p);
5433 (insn && GET_CODE (insn) == NOTE
5434 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_LOOP_BEG);
5435 insn = PREV_INSN (insn))
5439 set = single_set (insn);
5441 if (set && SET_DEST (set) == XEXP (x, 0)
5442 && GET_CODE (XEXP (x, 1)) == CONST_INT
5443 && INTVAL (XEXP (x, 1)) >= 0
5444 && GET_CODE (SET_SRC (set)) == ASHIFT
5445 && XEXP (x, 1) == XEXP (SET_SRC (set), 1))
5446 return basic_induction_var (XEXP (SET_SRC (set), 0),
5447 GET_MODE (XEXP (x, 0)),
5448 dest_reg, insn, inc_val, mult_val);
5456 /* A general induction variable (giv) is any quantity that is a linear
5457 function of a basic induction variable,
5458 i.e. giv = biv * mult_val + add_val.
5459 The coefficients can be any loop invariant quantity.
5460 A giv need not be computed directly from the biv;
5461 it can be computed by way of other givs. */
5463 /* Determine whether X computes a giv.
5464 If it does, return a nonzero value
5465 which is the benefit from eliminating the computation of X;
5466 set *SRC_REG to the register of the biv that it is computed from;
5467 set *ADD_VAL and *MULT_VAL to the coefficients,
5468 such that the value of X is biv * mult + add; */
5471 general_induction_var (x, src_reg, add_val, mult_val, is_addr, pbenefit)
5482 /* If this is an invariant, forget it, it isn't a giv. */
5483 if (invariant_p (x) == 1)
5486 /* See if the expression could be a giv and get its form.
5487 Mark our place on the obstack in case we don't find a giv. */
5488 storage = (char *) oballoc (0);
5490 x = simplify_giv_expr (x, pbenefit);
5497 switch (GET_CODE (x))
5501 /* Since this is now an invariant and wasn't before, it must be a giv
5502 with MULT_VAL == 0. It doesn't matter which BIV we associate this
5504 *src_reg = loop_iv_list->biv->dest_reg;
5505 *mult_val = const0_rtx;
5510 /* This is equivalent to a BIV. */
5512 *mult_val = const1_rtx;
5513 *add_val = const0_rtx;
5517 /* Either (plus (biv) (invar)) or
5518 (plus (mult (biv) (invar_1)) (invar_2)). */
5519 if (GET_CODE (XEXP (x, 0)) == MULT)
5521 *src_reg = XEXP (XEXP (x, 0), 0);
5522 *mult_val = XEXP (XEXP (x, 0), 1);
5526 *src_reg = XEXP (x, 0);
5527 *mult_val = const1_rtx;
5529 *add_val = XEXP (x, 1);
5533 /* ADD_VAL is zero. */
5534 *src_reg = XEXP (x, 0);
5535 *mult_val = XEXP (x, 1);
5536 *add_val = const0_rtx;
5543 /* Remove any enclosing USE from ADD_VAL and MULT_VAL (there will be
5544 unless they are CONST_INT). */
5545 if (GET_CODE (*add_val) == USE)
5546 *add_val = XEXP (*add_val, 0);
5547 if (GET_CODE (*mult_val) == USE)
5548 *mult_val = XEXP (*mult_val, 0);
5553 *pbenefit += ADDRESS_COST (orig_x) - reg_address_cost;
5555 *pbenefit += rtx_cost (orig_x, MEM) - reg_address_cost;
5559 *pbenefit += rtx_cost (orig_x, SET);
5561 /* Always return true if this is a giv so it will be detected as such,
5562 even if the benefit is zero or negative. This allows elimination
5563 of bivs that might otherwise not be eliminated. */
5567 /* Given an expression, X, try to form it as a linear function of a biv.
5568 We will canonicalize it to be of the form
5569 (plus (mult (BIV) (invar_1))
5571 with possible degeneracies.
5573 The invariant expressions must each be of a form that can be used as a
5574 machine operand. We surround then with a USE rtx (a hack, but localized
5575 and certainly unambiguous!) if not a CONST_INT for simplicity in this
5576 routine; it is the caller's responsibility to strip them.
5578 If no such canonicalization is possible (i.e., two biv's are used or an
5579 expression that is neither invariant nor a biv or giv), this routine
5582 For a non-zero return, the result will have a code of CONST_INT, USE,
5583 REG (for a BIV), PLUS, or MULT. No other codes will occur.
5585 *BENEFIT will be incremented by the benefit of any sub-giv encountered. */
5587 static rtx sge_plus PROTO ((enum machine_mode, rtx, rtx));
5588 static rtx sge_plus_constant PROTO ((rtx, rtx));
5591 simplify_giv_expr (x, benefit)
5595 enum machine_mode mode = GET_MODE (x);
5599 /* If this is not an integer mode, or if we cannot do arithmetic in this
5600 mode, this can't be a giv. */
5601 if (mode != VOIDmode
5602 && (GET_MODE_CLASS (mode) != MODE_INT
5603 || GET_MODE_BITSIZE (mode) > HOST_BITS_PER_WIDE_INT))
5606 switch (GET_CODE (x))
5609 arg0 = simplify_giv_expr (XEXP (x, 0), benefit);
5610 arg1 = simplify_giv_expr (XEXP (x, 1), benefit);
5611 if (arg0 == 0 || arg1 == 0)
5614 /* Put constant last, CONST_INT last if both constant. */
5615 if ((GET_CODE (arg0) == USE
5616 || GET_CODE (arg0) == CONST_INT)
5617 && ! ((GET_CODE (arg0) == USE
5618 && GET_CODE (arg1) == USE)
5619 || GET_CODE (arg1) == CONST_INT))
5620 tem = arg0, arg0 = arg1, arg1 = tem;
5622 /* Handle addition of zero, then addition of an invariant. */
5623 if (arg1 == const0_rtx)
5625 else if (GET_CODE (arg1) == CONST_INT || GET_CODE (arg1) == USE)
5626 switch (GET_CODE (arg0))
5630 /* Adding two invariants must result in an invariant, so enclose
5631 addition operation inside a USE and return it. */
5632 if (GET_CODE (arg0) == USE)
5633 arg0 = XEXP (arg0, 0);
5634 if (GET_CODE (arg1) == USE)
5635 arg1 = XEXP (arg1, 0);
5637 if (GET_CODE (arg0) == CONST_INT)
5638 tem = arg0, arg0 = arg1, arg1 = tem;
5639 if (GET_CODE (arg1) == CONST_INT)
5640 tem = sge_plus_constant (arg0, arg1);
5642 tem = sge_plus (mode, arg0, arg1);
5644 if (GET_CODE (tem) != CONST_INT)
5645 tem = gen_rtx_USE (mode, tem);
5650 /* biv + invar or mult + invar. Return sum. */
5651 return gen_rtx_PLUS (mode, arg0, arg1);
5654 /* (a + invar_1) + invar_2. Associate. */
5655 return simplify_giv_expr (
5656 gen_rtx_PLUS (mode, XEXP (arg0, 0),
5657 gen_rtx_PLUS (mode, XEXP (arg0, 1), arg1)),
5664 /* Each argument must be either REG, PLUS, or MULT. Convert REG to
5665 MULT to reduce cases. */
5666 if (GET_CODE (arg0) == REG)
5667 arg0 = gen_rtx_MULT (mode, arg0, const1_rtx);
5668 if (GET_CODE (arg1) == REG)
5669 arg1 = gen_rtx_MULT (mode, arg1, const1_rtx);
5671 /* Now have PLUS + PLUS, PLUS + MULT, MULT + PLUS, or MULT + MULT.
5672 Put a MULT first, leaving PLUS + PLUS, MULT + PLUS, or MULT + MULT.
5673 Recurse to associate the second PLUS. */
5674 if (GET_CODE (arg1) == MULT)
5675 tem = arg0, arg0 = arg1, arg1 = tem;
5677 if (GET_CODE (arg1) == PLUS)
5678 return simplify_giv_expr (gen_rtx_PLUS (mode,
5679 gen_rtx_PLUS (mode, arg0,
5684 /* Now must have MULT + MULT. Distribute if same biv, else not giv. */
5685 if (GET_CODE (arg0) != MULT || GET_CODE (arg1) != MULT)
5688 if (!rtx_equal_p (arg0, arg1))
5691 return simplify_giv_expr (gen_rtx_MULT (mode,
5699 /* Handle "a - b" as "a + b * (-1)". */
5700 return simplify_giv_expr (gen_rtx_PLUS (mode,
5702 gen_rtx_MULT (mode, XEXP (x, 1),
5707 arg0 = simplify_giv_expr (XEXP (x, 0), benefit);
5708 arg1 = simplify_giv_expr (XEXP (x, 1), benefit);
5709 if (arg0 == 0 || arg1 == 0)
5712 /* Put constant last, CONST_INT last if both constant. */
5713 if ((GET_CODE (arg0) == USE || GET_CODE (arg0) == CONST_INT)
5714 && GET_CODE (arg1) != CONST_INT)
5715 tem = arg0, arg0 = arg1, arg1 = tem;
5717 /* If second argument is not now constant, not giv. */
5718 if (GET_CODE (arg1) != USE && GET_CODE (arg1) != CONST_INT)
5721 /* Handle multiply by 0 or 1. */
5722 if (arg1 == const0_rtx)
5725 else if (arg1 == const1_rtx)
5728 switch (GET_CODE (arg0))
5731 /* biv * invar. Done. */
5732 return gen_rtx_MULT (mode, arg0, arg1);
5735 /* Product of two constants. */
5736 return GEN_INT (INTVAL (arg0) * INTVAL (arg1));
5739 /* invar * invar. It is a giv, but very few of these will
5740 actually pay off, so limit to simple registers. */
5741 if (GET_CODE (arg1) != CONST_INT)
5744 arg0 = XEXP (arg0, 0);
5745 if (GET_CODE (arg0) == REG)
5746 tem = gen_rtx_MULT (mode, arg0, arg1);
5747 else if (GET_CODE (arg0) == MULT
5748 && GET_CODE (XEXP (arg0, 0)) == REG
5749 && GET_CODE (XEXP (arg0, 1)) == CONST_INT)
5751 tem = gen_rtx_MULT (mode, XEXP (arg0, 0),
5752 GEN_INT (INTVAL (XEXP (arg0, 1))
5757 return gen_rtx_USE (mode, tem);
5760 /* (a * invar_1) * invar_2. Associate. */
5761 return simplify_giv_expr (gen_rtx_MULT (mode, XEXP (arg0, 0),
5768 /* (a + invar_1) * invar_2. Distribute. */
5769 return simplify_giv_expr (gen_rtx_PLUS (mode,
5783 /* Shift by constant is multiply by power of two. */
5784 if (GET_CODE (XEXP (x, 1)) != CONST_INT)
5787 return simplify_giv_expr (gen_rtx_MULT (mode,
5789 GEN_INT ((HOST_WIDE_INT) 1
5790 << INTVAL (XEXP (x, 1)))),
5794 /* "-a" is "a * (-1)" */
5795 return simplify_giv_expr (gen_rtx_MULT (mode, XEXP (x, 0), constm1_rtx),
5799 /* "~a" is "-a - 1". Silly, but easy. */
5800 return simplify_giv_expr (gen_rtx_MINUS (mode,
5801 gen_rtx_NEG (mode, XEXP (x, 0)),
5806 /* Already in proper form for invariant. */
5810 /* If this is a new register, we can't deal with it. */
5811 if (REGNO (x) >= max_reg_before_loop)
5814 /* Check for biv or giv. */
5815 switch (reg_iv_type[REGNO (x)])
5819 case GENERAL_INDUCT:
5821 struct induction *v = reg_iv_info[REGNO (x)];
5823 /* Form expression from giv and add benefit. Ensure this giv
5824 can derive another and subtract any needed adjustment if so. */
5825 *benefit += v->benefit;
5829 tem = gen_rtx_PLUS (mode, gen_rtx_MULT (mode, v->src_reg,
5832 if (v->derive_adjustment)
5833 tem = gen_rtx_MINUS (mode, tem, v->derive_adjustment);
5834 return simplify_giv_expr (tem, benefit);
5838 /* If it isn't an induction variable, and it is invariant, we
5839 may be able to simplify things further by looking through
5840 the bits we just moved outside the loop. */
5841 if (invariant_p (x) == 1)
5845 for (m = the_movables; m ; m = m->next)
5846 if (rtx_equal_p (x, m->set_dest))
5848 /* Ok, we found a match. Substitute and simplify. */
5850 /* If we match another movable, we must use that, as
5851 this one is going away. */
5853 return simplify_giv_expr (m->match->set_dest, benefit);
5855 /* If consec is non-zero, this is a member of a group of
5856 instructions that were moved together. We handle this
5857 case only to the point of seeking to the last insn and
5858 looking for a REG_EQUAL. Fail if we don't find one. */
5863 do { tem = NEXT_INSN (tem); } while (--i > 0);
5865 tem = find_reg_note (tem, REG_EQUAL, NULL_RTX);
5867 tem = XEXP (tem, 0);
5871 tem = single_set (m->insn);
5873 tem = SET_SRC (tem);
5878 /* What we are most interested in is pointer
5879 arithmetic on invariants -- only take
5880 patterns we may be able to do something with. */
5881 if (GET_CODE (tem) == PLUS
5882 || GET_CODE (tem) == MULT
5883 || GET_CODE (tem) == ASHIFT
5884 || GET_CODE (tem) == CONST_INT
5885 || GET_CODE (tem) == SYMBOL_REF)
5887 tem = simplify_giv_expr (tem, benefit);
5891 else if (GET_CODE (tem) == CONST
5892 && GET_CODE (XEXP (tem, 0)) == PLUS
5893 && GET_CODE (XEXP (XEXP (tem, 0), 0)) == SYMBOL_REF
5894 && GET_CODE (XEXP (XEXP (tem, 0), 1)) == CONST_INT)
5896 tem = simplify_giv_expr (XEXP (tem, 0), benefit);
5907 /* Fall through to general case. */
5909 /* If invariant, return as USE (unless CONST_INT).
5910 Otherwise, not giv. */
5911 if (GET_CODE (x) == USE)
5914 if (invariant_p (x) == 1)
5916 if (GET_CODE (x) == CONST_INT)
5918 if (GET_CODE (x) == CONST
5919 && GET_CODE (XEXP (x, 0)) == PLUS
5920 && GET_CODE (XEXP (XEXP (x, 0), 0)) == SYMBOL_REF
5921 && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT)
5923 return gen_rtx_USE (mode, x);
5930 /* This routine folds invariants such that there is only ever one
5931 CONST_INT in the summation. It is only used by simplify_giv_expr. */
5934 sge_plus_constant (x, c)
5937 if (GET_CODE (x) == CONST_INT)
5938 return GEN_INT (INTVAL (x) + INTVAL (c));
5939 else if (GET_CODE (x) != PLUS)
5940 return gen_rtx_PLUS (GET_MODE (x), x, c);
5941 else if (GET_CODE (XEXP (x, 1)) == CONST_INT)
5943 return gen_rtx_PLUS (GET_MODE (x), XEXP (x, 0),
5944 GEN_INT (INTVAL (XEXP (x, 1)) + INTVAL (c)));
5946 else if (GET_CODE (XEXP (x, 0)) == PLUS
5947 || GET_CODE (XEXP (x, 1)) != PLUS)
5949 return gen_rtx_PLUS (GET_MODE (x),
5950 sge_plus_constant (XEXP (x, 0), c), XEXP (x, 1));
5954 return gen_rtx_PLUS (GET_MODE (x),
5955 sge_plus_constant (XEXP (x, 1), c), XEXP (x, 0));
5960 sge_plus (mode, x, y)
5961 enum machine_mode mode;
5964 while (GET_CODE (y) == PLUS)
5966 rtx a = XEXP (y, 0);
5967 if (GET_CODE (a) == CONST_INT)
5968 x = sge_plus_constant (x, a);
5970 x = gen_rtx_PLUS (mode, x, a);
5973 if (GET_CODE (y) == CONST_INT)
5974 x = sge_plus_constant (x, y);
5976 x = gen_rtx_PLUS (mode, x, y);
5980 /* Help detect a giv that is calculated by several consecutive insns;
5984 The caller has already identified the first insn P as having a giv as dest;
5985 we check that all other insns that set the same register follow
5986 immediately after P, that they alter nothing else,
5987 and that the result of the last is still a giv.
5989 The value is 0 if the reg set in P is not really a giv.
5990 Otherwise, the value is the amount gained by eliminating
5991 all the consecutive insns that compute the value.
5993 FIRST_BENEFIT is the amount gained by eliminating the first insn, P.
5994 SRC_REG is the reg of the biv; DEST_REG is the reg of the giv.
5996 The coefficients of the ultimate giv value are stored in
5997 *MULT_VAL and *ADD_VAL. */
6000 consec_sets_giv (first_benefit, p, src_reg, dest_reg,
6015 /* Indicate that this is a giv so that we can update the value produced in
6016 each insn of the multi-insn sequence.
6018 This induction structure will be used only by the call to
6019 general_induction_var below, so we can allocate it on our stack.
6020 If this is a giv, our caller will replace the induct var entry with
6021 a new induction structure. */
6023 = (struct induction *) alloca (sizeof (struct induction));
6024 v->src_reg = src_reg;
6025 v->mult_val = *mult_val;
6026 v->add_val = *add_val;
6027 v->benefit = first_benefit;
6029 v->derive_adjustment = 0;
6031 reg_iv_type[REGNO (dest_reg)] = GENERAL_INDUCT;
6032 reg_iv_info[REGNO (dest_reg)] = v;
6034 count = VARRAY_INT (n_times_set, REGNO (dest_reg)) - 1;
6039 code = GET_CODE (p);
6041 /* If libcall, skip to end of call sequence. */
6042 if (code == INSN && (temp = find_reg_note (p, REG_LIBCALL, NULL_RTX)))
6046 && (set = single_set (p))
6047 && GET_CODE (SET_DEST (set)) == REG
6048 && SET_DEST (set) == dest_reg
6049 && (general_induction_var (SET_SRC (set), &src_reg,
6050 add_val, mult_val, 0, &benefit)
6051 /* Giv created by equivalent expression. */
6052 || ((temp = find_reg_note (p, REG_EQUAL, NULL_RTX))
6053 && general_induction_var (XEXP (temp, 0), &src_reg,
6054 add_val, mult_val, 0, &benefit)))
6055 && src_reg == v->src_reg)
6057 if (find_reg_note (p, REG_RETVAL, NULL_RTX))
6058 benefit += libcall_benefit (p);
6061 v->mult_val = *mult_val;
6062 v->add_val = *add_val;
6063 v->benefit = benefit;
6065 else if (code != NOTE)
6067 /* Allow insns that set something other than this giv to a
6068 constant. Such insns are needed on machines which cannot
6069 include long constants and should not disqualify a giv. */
6071 && (set = single_set (p))
6072 && SET_DEST (set) != dest_reg
6073 && CONSTANT_P (SET_SRC (set)))
6076 reg_iv_type[REGNO (dest_reg)] = UNKNOWN_INDUCT;
6084 /* Return an rtx, if any, that expresses giv G2 as a function of the register
6085 represented by G1. If no such expression can be found, or it is clear that
6086 it cannot possibly be a valid address, 0 is returned.
6088 To perform the computation, we note that
6091 where `v' is the biv.
6093 So G2 = (y/b) * G1 + (b - a*y/x).
6095 Note that MULT = y/x.
6097 Update: A and B are now allowed to be additive expressions such that
6098 B contains all variables in A. That is, computing B-A will not require
6099 subtracting variables. */
6102 express_from_1 (a, b, mult)
6105 /* If MULT is zero, then A*MULT is zero, and our expression is B. */
6107 if (mult == const0_rtx)
6110 /* If MULT is not 1, we cannot handle A with non-constants, since we
6111 would then be required to subtract multiples of the registers in A.
6112 This is theoretically possible, and may even apply to some Fortran
6113 constructs, but it is a lot of work and we do not attempt it here. */
6115 if (mult != const1_rtx && GET_CODE (a) != CONST_INT)
6118 /* In general these structures are sorted top to bottom (down the PLUS
6119 chain), but not left to right across the PLUS. If B is a higher
6120 order giv than A, we can strip one level and recurse. If A is higher
6121 order, we'll eventually bail out, but won't know that until the end.
6122 If they are the same, we'll strip one level around this loop. */
6124 while (GET_CODE (a) == PLUS && GET_CODE (b) == PLUS)
6126 rtx ra, rb, oa, ob, tmp;
6128 ra = XEXP (a, 0), oa = XEXP (a, 1);
6129 if (GET_CODE (ra) == PLUS)
6130 tmp = ra, ra = oa, oa = tmp;
6132 rb = XEXP (b, 0), ob = XEXP (b, 1);
6133 if (GET_CODE (rb) == PLUS)
6134 tmp = rb, rb = ob, ob = tmp;
6136 if (rtx_equal_p (ra, rb))
6137 /* We matched: remove one reg completely. */
6139 else if (GET_CODE (ob) != PLUS && rtx_equal_p (ra, ob))
6140 /* An alternate match. */
6142 else if (GET_CODE (oa) != PLUS && rtx_equal_p (oa, rb))
6143 /* An alternate match. */
6147 /* Indicates an extra register in B. Strip one level from B and
6148 recurse, hoping B was the higher order expression. */
6149 ob = express_from_1 (a, ob, mult);
6152 return gen_rtx_PLUS (GET_MODE (b), rb, ob);
6156 /* Here we are at the last level of A, go through the cases hoping to
6157 get rid of everything but a constant. */
6159 if (GET_CODE (a) == PLUS)
6163 ra = XEXP (a, 0), oa = XEXP (a, 1);
6164 if (rtx_equal_p (oa, b))
6166 else if (!rtx_equal_p (ra, b))
6169 if (GET_CODE (oa) != CONST_INT)
6172 return GEN_INT (-INTVAL (oa) * INTVAL (mult));
6174 else if (GET_CODE (a) == CONST_INT)
6176 return plus_constant (b, -INTVAL (a) * INTVAL (mult));
6178 else if (GET_CODE (b) == PLUS)
6180 if (rtx_equal_p (a, XEXP (b, 0)))
6182 else if (rtx_equal_p (a, XEXP (b, 1)))
6187 else if (rtx_equal_p (a, b))
6194 express_from (g1, g2)
6195 struct induction *g1, *g2;
6199 /* The value that G1 will be multiplied by must be a constant integer. Also,
6200 the only chance we have of getting a valid address is if b*c/a (see above
6201 for notation) is also an integer. */
6202 if (GET_CODE (g1->mult_val) == CONST_INT
6203 && GET_CODE (g2->mult_val) == CONST_INT)
6205 if (g1->mult_val == const0_rtx
6206 || INTVAL (g2->mult_val) % INTVAL (g1->mult_val) != 0)
6208 mult = GEN_INT (INTVAL (g2->mult_val) / INTVAL (g1->mult_val));
6210 else if (rtx_equal_p (g1->mult_val, g2->mult_val))
6214 /* ??? Find out if the one is a multiple of the other? */
6218 add = express_from_1 (g1->add_val, g2->add_val, mult);
6219 if (add == NULL_RTX)
6222 /* Form simplified final result. */
6223 if (mult == const0_rtx)
6225 else if (mult == const1_rtx)
6226 mult = g1->dest_reg;
6228 mult = gen_rtx_MULT (g2->mode, g1->dest_reg, mult);
6230 if (add == const0_rtx)
6233 return gen_rtx_PLUS (g2->mode, mult, add);
6236 /* Return an rtx, if any, that expresses giv G2 as a function of the register
6237 represented by G1. This indicates that G2 should be combined with G1 and
6238 that G2 can use (either directly or via an address expression) a register
6239 used to represent G1. */
6242 combine_givs_p (g1, g2)
6243 struct induction *g1, *g2;
6245 rtx tem = express_from (g1, g2);
6247 /* If these givs are identical, they can be combined. We use the results
6248 of express_from because the addends are not in a canonical form, so
6249 rtx_equal_p is a weaker test. */
6250 if (tem == g1->dest_reg)
6252 return g1->dest_reg;
6255 /* If G2 can be expressed as a function of G1 and that function is valid
6256 as an address and no more expensive than using a register for G2,
6257 the expression of G2 in terms of G1 can be used. */
6259 && g2->giv_type == DEST_ADDR
6260 && memory_address_p (g2->mem_mode, tem)
6261 /* ??? Looses, especially with -fforce-addr, where *g2->location
6262 will always be a register, and so anything more complicated
6266 && ADDRESS_COST (tem) <= ADDRESS_COST (*g2->location)
6268 && rtx_cost (tem, MEM) <= rtx_cost (*g2->location, MEM)
6279 struct combine_givs_stats
6286 cmp_combine_givs_stats (x, y)
6287 struct combine_givs_stats *x, *y;
6290 d = y->total_benefit - x->total_benefit;
6291 /* Stabilize the sort. */
6293 d = x->giv_number - y->giv_number;
6297 /* If one of these givs is a DEST_REG that was only used once, by the
6298 other giv, this is actually a single use. Return 0 if this is not
6299 the case, -1 if g1 is the DEST_REG involved, and 1 if it was g2. */
6302 combine_givs_used_once (g1, g2)
6303 struct induction *g1, *g2;
6305 if (g1->giv_type == DEST_REG
6306 && VARRAY_INT (n_times_used, REGNO (g1->dest_reg)) == 1
6307 && reg_mentioned_p (g1->dest_reg, PATTERN (g2->insn)))
6310 if (g2->giv_type == DEST_REG
6311 && VARRAY_INT (n_times_used, REGNO (g2->dest_reg)) == 1
6312 && reg_mentioned_p (g2->dest_reg, PATTERN (g1->insn)))
6319 combine_givs_benefit_from (g1, g2)
6320 struct induction *g1, *g2;
6322 int tmp = combine_givs_used_once (g1, g2);
6326 return g2->benefit - g1->benefit;
6331 /* Check all pairs of givs for iv_class BL and see if any can be combined with
6332 any other. If so, point SAME to the giv combined with and set NEW_REG to
6333 be an expression (in terms of the other giv's DEST_REG) equivalent to the
6334 giv. Also, update BENEFIT and related fields for cost/benefit analysis. */
6338 struct iv_class *bl;
6340 struct induction *g1, *g2, **giv_array;
6341 int i, j, k, giv_count;
6342 struct combine_givs_stats *stats;
6345 /* Count givs, because bl->giv_count is incorrect here. */
6347 for (g1 = bl->giv; g1; g1 = g1->next_iv)
6352 = (struct induction **) alloca (giv_count * sizeof (struct induction *));
6354 for (g1 = bl->giv; g1; g1 = g1->next_iv)
6356 giv_array[i++] = g1;
6358 stats = (struct combine_givs_stats *) alloca (giv_count * sizeof (*stats));
6359 bzero ((char *) stats, giv_count * sizeof (*stats));
6361 can_combine = (rtx *) alloca (giv_count * giv_count * sizeof(rtx));
6362 bzero ((char *) can_combine, giv_count * giv_count * sizeof(rtx));
6364 for (i = 0; i < giv_count; i++)
6370 this_benefit = g1->benefit;
6371 /* Add an additional weight for zero addends. */
6372 if (g1->no_const_addval)
6374 for (j = 0; j < giv_count; j++)
6380 && (this_combine = combine_givs_p (g1, g2)) != NULL_RTX)
6382 can_combine[i*giv_count + j] = this_combine;
6383 this_benefit += combine_givs_benefit_from (g1, g2);
6384 /* Add an additional weight for being reused more times. */
6388 stats[i].giv_number = i;
6389 stats[i].total_benefit = this_benefit;
6392 /* Iterate, combining until we can't. */
6394 qsort (stats, giv_count, sizeof(*stats), cmp_combine_givs_stats);
6396 if (loop_dump_stream)
6398 fprintf (loop_dump_stream, "Sorted combine statistics:\n");
6399 for (k = 0; k < giv_count; k++)
6401 g1 = giv_array[stats[k].giv_number];
6402 if (!g1->combined_with && !g1->same)
6403 fprintf (loop_dump_stream, " {%d, %d}",
6404 INSN_UID (giv_array[stats[k].giv_number]->insn),
6405 stats[k].total_benefit);
6407 putc ('\n', loop_dump_stream);
6410 for (k = 0; k < giv_count; k++)
6412 int g1_add_benefit = 0;
6414 i = stats[k].giv_number;
6417 /* If it has already been combined, skip. */
6418 if (g1->combined_with || g1->same)
6421 for (j = 0; j < giv_count; j++)
6424 if (g1 != g2 && can_combine[i*giv_count + j]
6425 /* If it has already been combined, skip. */
6426 && ! g2->same && ! g2->combined_with)
6430 g2->new_reg = can_combine[i*giv_count + j];
6432 g1->combined_with = 1;
6433 if (!combine_givs_used_once (g1, g2))
6434 g1->times_used += 1;
6435 g1->lifetime += g2->lifetime;
6437 g1_add_benefit += combine_givs_benefit_from (g1, g2);
6439 /* ??? The new final_[bg]iv_value code does a much better job
6440 of finding replaceable giv's, and hence this code may no
6441 longer be necessary. */
6442 if (! g2->replaceable && REG_USERVAR_P (g2->dest_reg))
6443 g1_add_benefit -= copy_cost;
6445 /* To help optimize the next set of combinations, remove
6446 this giv from the benefits of other potential mates. */
6447 for (l = 0; l < giv_count; ++l)
6449 int m = stats[l].giv_number;
6450 if (can_combine[m*giv_count + j])
6452 /* Remove additional weight for being reused. */
6453 stats[l].total_benefit -= 3 +
6454 combine_givs_benefit_from (giv_array[m], g2);
6458 if (loop_dump_stream)
6459 fprintf (loop_dump_stream,
6460 "giv at %d combined with giv at %d\n",
6461 INSN_UID (g2->insn), INSN_UID (g1->insn));
6465 /* To help optimize the next set of combinations, remove
6466 this giv from the benefits of other potential mates. */
6467 if (g1->combined_with)
6469 for (j = 0; j < giv_count; ++j)
6471 int m = stats[j].giv_number;
6472 if (can_combine[m*giv_count + j])
6474 /* Remove additional weight for being reused. */
6475 stats[j].total_benefit -= 3 +
6476 combine_givs_benefit_from (giv_array[m], g1);
6480 g1->benefit += g1_add_benefit;
6482 /* We've finished with this giv, and everything it touched.
6483 Restart the combination so that proper weights for the
6484 rest of the givs are properly taken into account. */
6485 /* ??? Ideally we would compact the arrays at this point, so
6486 as to not cover old ground. But sanely compacting
6487 can_combine is tricky. */
6493 /* EMIT code before INSERT_BEFORE to set REG = B * M + A. */
6496 emit_iv_add_mult (b, m, a, reg, insert_before)
6497 rtx b; /* initial value of basic induction variable */
6498 rtx m; /* multiplicative constant */
6499 rtx a; /* additive constant */
6500 rtx reg; /* destination register */
6506 /* Prevent unexpected sharing of these rtx. */
6510 /* Increase the lifetime of any invariants moved further in code. */
6511 update_reg_last_use (a, insert_before);
6512 update_reg_last_use (b, insert_before);
6513 update_reg_last_use (m, insert_before);
6516 result = expand_mult_add (b, reg, m, a, GET_MODE (reg), 0);
6518 emit_move_insn (reg, result);
6519 seq = gen_sequence ();
6522 emit_insn_before (seq, insert_before);
6524 /* It is entirely possible that the expansion created lots of new
6525 registers. Iterate over the sequence we just created and
6528 if (GET_CODE (seq) == SEQUENCE)
6531 for (i = 0; i < XVECLEN (seq, 0); ++i)
6533 rtx set = single_set (XVECEXP (seq, 0, i));
6534 if (set && GET_CODE (SET_DEST (set)) == REG)
6535 record_base_value (REGNO (SET_DEST (set)), SET_SRC (set), 0);
6538 else if (GET_CODE (seq) == SET
6539 && GET_CODE (SET_DEST (seq)) == REG)
6540 record_base_value (REGNO (SET_DEST (seq)), SET_SRC (seq), 0);
6543 /* Test whether A * B can be computed without
6544 an actual multiply insn. Value is 1 if so. */
6547 product_cheap_p (a, b)
6553 struct obstack *old_rtl_obstack = rtl_obstack;
6554 char *storage = (char *) obstack_alloc (&temp_obstack, 0);
6557 /* If only one is constant, make it B. */
6558 if (GET_CODE (a) == CONST_INT)
6559 tmp = a, a = b, b = tmp;
6561 /* If first constant, both constant, so don't need multiply. */
6562 if (GET_CODE (a) == CONST_INT)
6565 /* If second not constant, neither is constant, so would need multiply. */
6566 if (GET_CODE (b) != CONST_INT)
6569 /* One operand is constant, so might not need multiply insn. Generate the
6570 code for the multiply and see if a call or multiply, or long sequence
6571 of insns is generated. */
6573 rtl_obstack = &temp_obstack;
6575 expand_mult (GET_MODE (a), a, b, NULL_RTX, 0);
6576 tmp = gen_sequence ();
6579 if (GET_CODE (tmp) == SEQUENCE)
6581 if (XVEC (tmp, 0) == 0)
6583 else if (XVECLEN (tmp, 0) > 3)
6586 for (i = 0; i < XVECLEN (tmp, 0); i++)
6588 rtx insn = XVECEXP (tmp, 0, i);
6590 if (GET_CODE (insn) != INSN
6591 || (GET_CODE (PATTERN (insn)) == SET
6592 && GET_CODE (SET_SRC (PATTERN (insn))) == MULT)
6593 || (GET_CODE (PATTERN (insn)) == PARALLEL
6594 && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == SET
6595 && GET_CODE (SET_SRC (XVECEXP (PATTERN (insn), 0, 0))) == MULT))
6602 else if (GET_CODE (tmp) == SET
6603 && GET_CODE (SET_SRC (tmp)) == MULT)
6605 else if (GET_CODE (tmp) == PARALLEL
6606 && GET_CODE (XVECEXP (tmp, 0, 0)) == SET
6607 && GET_CODE (SET_SRC (XVECEXP (tmp, 0, 0))) == MULT)
6610 /* Free any storage we obtained in generating this multiply and restore rtl
6611 allocation to its normal obstack. */
6612 obstack_free (&temp_obstack, storage);
6613 rtl_obstack = old_rtl_obstack;
6618 /* Check to see if loop can be terminated by a "decrement and branch until
6619 zero" instruction. If so, add a REG_NONNEG note to the branch insn if so.
6620 Also try reversing an increment loop to a decrement loop
6621 to see if the optimization can be performed.
6622 Value is nonzero if optimization was performed. */
6624 /* This is useful even if the architecture doesn't have such an insn,
6625 because it might change a loops which increments from 0 to n to a loop
6626 which decrements from n to 0. A loop that decrements to zero is usually
6627 faster than one that increments from zero. */
6629 /* ??? This could be rewritten to use some of the loop unrolling procedures,
6630 such as approx_final_value, biv_total_increment, loop_iterations, and
6631 final_[bg]iv_value. */
6634 check_dbra_loop (loop_end, insn_count, loop_start)
6639 struct iv_class *bl;
6646 rtx before_comparison;
6650 int compare_and_branch;
6652 /* If last insn is a conditional branch, and the insn before tests a
6653 register value, try to optimize it. Otherwise, we can't do anything. */
6655 jump = PREV_INSN (loop_end);
6656 comparison = get_condition_for_loop (jump);
6657 if (comparison == 0)
6660 /* Try to compute whether the compare/branch at the loop end is one or
6661 two instructions. */
6662 get_condition (jump, &first_compare);
6663 if (first_compare == jump)
6664 compare_and_branch = 1;
6665 else if (first_compare == prev_nonnote_insn (jump))
6666 compare_and_branch = 2;
6670 /* Check all of the bivs to see if the compare uses one of them.
6671 Skip biv's set more than once because we can't guarantee that
6672 it will be zero on the last iteration. Also skip if the biv is
6673 used between its update and the test insn. */
6675 for (bl = loop_iv_list; bl; bl = bl->next)
6677 if (bl->biv_count == 1
6678 && bl->biv->dest_reg == XEXP (comparison, 0)
6679 && ! reg_used_between_p (regno_reg_rtx[bl->regno], bl->biv->insn,
6687 /* Look for the case where the basic induction variable is always
6688 nonnegative, and equals zero on the last iteration.
6689 In this case, add a reg_note REG_NONNEG, which allows the
6690 m68k DBRA instruction to be used. */
6692 if (((GET_CODE (comparison) == GT
6693 && GET_CODE (XEXP (comparison, 1)) == CONST_INT
6694 && INTVAL (XEXP (comparison, 1)) == -1)
6695 || (GET_CODE (comparison) == NE && XEXP (comparison, 1) == const0_rtx))
6696 && GET_CODE (bl->biv->add_val) == CONST_INT
6697 && INTVAL (bl->biv->add_val) < 0)
6699 /* Initial value must be greater than 0,
6700 init_val % -dec_value == 0 to ensure that it equals zero on
6701 the last iteration */
6703 if (GET_CODE (bl->initial_value) == CONST_INT
6704 && INTVAL (bl->initial_value) > 0
6705 && (INTVAL (bl->initial_value)
6706 % (-INTVAL (bl->biv->add_val))) == 0)
6708 /* register always nonnegative, add REG_NOTE to branch */
6709 REG_NOTES (PREV_INSN (loop_end))
6710 = gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX,
6711 REG_NOTES (PREV_INSN (loop_end)));
6717 /* If the decrement is 1 and the value was tested as >= 0 before
6718 the loop, then we can safely optimize. */
6719 for (p = loop_start; p; p = PREV_INSN (p))
6721 if (GET_CODE (p) == CODE_LABEL)
6723 if (GET_CODE (p) != JUMP_INSN)
6726 before_comparison = get_condition_for_loop (p);
6727 if (before_comparison
6728 && XEXP (before_comparison, 0) == bl->biv->dest_reg
6729 && GET_CODE (before_comparison) == LT
6730 && XEXP (before_comparison, 1) == const0_rtx
6731 && ! reg_set_between_p (bl->biv->dest_reg, p, loop_start)
6732 && INTVAL (bl->biv->add_val) == -1)
6734 REG_NOTES (PREV_INSN (loop_end))
6735 = gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX,
6736 REG_NOTES (PREV_INSN (loop_end)));
6743 else if (INTVAL (bl->biv->add_val) > 0)
6745 /* Try to change inc to dec, so can apply above optimization. */
6747 all registers modified are induction variables or invariant,
6748 all memory references have non-overlapping addresses
6749 (obviously true if only one write)
6750 allow 2 insns for the compare/jump at the end of the loop. */
6751 /* Also, we must avoid any instructions which use both the reversed
6752 biv and another biv. Such instructions will fail if the loop is
6753 reversed. We meet this condition by requiring that either
6754 no_use_except_counting is true, or else that there is only
6756 int num_nonfixed_reads = 0;
6757 /* 1 if the iteration var is used only to count iterations. */
6758 int no_use_except_counting = 0;
6759 /* 1 if the loop has no memory store, or it has a single memory store
6760 which is reversible. */
6761 int reversible_mem_store = 1;
6763 if (bl->giv_count == 0
6764 && ! loop_number_exit_count[uid_loop_num[INSN_UID (loop_start)]])
6766 rtx bivreg = regno_reg_rtx[bl->regno];
6768 /* If there are no givs for this biv, and the only exit is the
6769 fall through at the end of the loop, then
6770 see if perhaps there are no uses except to count. */
6771 no_use_except_counting = 1;
6772 for (p = loop_start; p != loop_end; p = NEXT_INSN (p))
6773 if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
6775 rtx set = single_set (p);
6777 if (set && GET_CODE (SET_DEST (set)) == REG
6778 && REGNO (SET_DEST (set)) == bl->regno)
6779 /* An insn that sets the biv is okay. */
6781 else if (p == prev_nonnote_insn (prev_nonnote_insn (loop_end))
6782 || p == prev_nonnote_insn (loop_end))
6783 /* Don't bother about the end test. */
6785 else if (reg_mentioned_p (bivreg, PATTERN (p)))
6787 no_use_except_counting = 0;
6793 if (no_use_except_counting)
6794 ; /* no need to worry about MEMs. */
6795 else if (num_mem_sets <= 1)
6797 for (p = loop_start; p != loop_end; p = NEXT_INSN (p))
6798 if (GET_RTX_CLASS (GET_CODE (p)) == 'i')
6799 num_nonfixed_reads += count_nonfixed_reads (PATTERN (p));
6801 /* If the loop has a single store, and the destination address is
6802 invariant, then we can't reverse the loop, because this address
6803 might then have the wrong value at loop exit.
6804 This would work if the source was invariant also, however, in that
6805 case, the insn should have been moved out of the loop. */
6807 if (num_mem_sets == 1)
6808 reversible_mem_store
6809 = (! unknown_address_altered
6810 && ! invariant_p (XEXP (loop_store_mems[0], 0)));
6815 /* This code only acts for innermost loops. Also it simplifies
6816 the memory address check by only reversing loops with
6817 zero or one memory access.
6818 Two memory accesses could involve parts of the same array,
6819 and that can't be reversed.
6820 If the biv is used only for counting, than we don't need to worry
6821 about all these things. */
6823 if ((num_nonfixed_reads <= 1
6825 && !loop_has_volatile
6826 && reversible_mem_store
6827 && (bl->giv_count + bl->biv_count + num_mem_sets
6828 + num_movables + compare_and_branch == insn_count)
6829 && (bl == loop_iv_list && bl->next == 0))
6830 || no_use_except_counting)
6834 /* Loop can be reversed. */
6835 if (loop_dump_stream)
6836 fprintf (loop_dump_stream, "Can reverse loop\n");
6838 /* Now check other conditions:
6840 The increment must be a constant, as must the initial value,
6841 and the comparison code must be LT.
6843 This test can probably be improved since +/- 1 in the constant
6844 can be obtained by changing LT to LE and vice versa; this is
6848 /* for constants, LE gets turned into LT */
6849 && (GET_CODE (comparison) == LT
6850 || (GET_CODE (comparison) == LE
6851 && no_use_except_counting)))
6853 HOST_WIDE_INT add_val, add_adjust, comparison_val;
6854 rtx initial_value, comparison_value;
6856 enum rtx_code cmp_code;
6857 int comparison_const_width;
6858 unsigned HOST_WIDE_INT comparison_sign_mask;
6861 add_val = INTVAL (bl->biv->add_val);
6862 comparison_value = XEXP (comparison, 1);
6863 comparison_const_width
6864 = GET_MODE_BITSIZE (GET_MODE (XEXP (comparison, 1)));
6865 if (comparison_const_width > HOST_BITS_PER_WIDE_INT)
6866 comparison_const_width = HOST_BITS_PER_WIDE_INT;
6867 comparison_sign_mask
6868 = (unsigned HOST_WIDE_INT)1 << (comparison_const_width - 1);
6870 /* If the comparison value is not a loop invariant, then we
6871 can not reverse this loop.
6873 ??? If the insns which initialize the comparison value as
6874 a whole compute an invariant result, then we could move
6875 them out of the loop and proceed with loop reversal. */
6876 if (!invariant_p (comparison_value))
6879 if (GET_CODE (comparison_value) == CONST_INT)
6880 comparison_val = INTVAL (comparison_value);
6881 initial_value = bl->initial_value;
6883 /* Normalize the initial value if it is an integer and
6884 has no other use except as a counter. This will allow
6885 a few more loops to be reversed. */
6886 if (no_use_except_counting
6887 && GET_CODE (comparison_value) == CONST_INT
6888 && GET_CODE (initial_value) == CONST_INT)
6890 comparison_val = comparison_val - INTVAL (bl->initial_value);
6891 /* The code below requires comparison_val to be a multiple
6892 of add_val in order to do the loop reversal, so
6893 round up comparison_val to a multiple of add_val.
6894 Since comparison_value is constant, we know that the
6895 current comparison code is LT. */
6896 comparison_val = comparison_val + add_val - 1;
6898 -= (unsigned HOST_WIDE_INT) comparison_val % add_val;
6899 /* We postpone overflow checks for COMPARISON_VAL here;
6900 even if there is an overflow, we might still be able to
6901 reverse the loop, if converting the loop exit test to
6903 initial_value = const0_rtx;
6906 /* Check if there is a NOTE_INSN_LOOP_VTOP note. If there is,
6907 that means that this is a for or while style loop, with
6908 a loop exit test at the start. Thus, we can assume that
6909 the loop condition was true when the loop was entered.
6910 This allows us to change the loop exit condition to an
6912 We start at the end and search backwards for the previous
6913 NOTE. If there is no NOTE_INSN_LOOP_VTOP for this loop,
6914 the search will stop at the NOTE_INSN_LOOP_CONT. */
6917 vtop = PREV_INSN (vtop);
6918 while (GET_CODE (vtop) != NOTE
6919 || NOTE_LINE_NUMBER (vtop) > 0
6920 || NOTE_LINE_NUMBER (vtop) == NOTE_REPEATED_LINE_NUMBER
6921 || NOTE_LINE_NUMBER (vtop) == NOTE_INSN_DELETED);
6922 if (NOTE_LINE_NUMBER (vtop) != NOTE_INSN_LOOP_VTOP)
6925 /* First check if we can do a vanilla loop reversal. */
6926 if (initial_value == const0_rtx
6927 /* If we have a decrement_and_branch_on_count, prefer
6928 the NE test, since this will allow that instruction to
6929 be generated. Note that we must use a vanilla loop
6930 reversal if the biv is used to calculate a giv or has
6931 a non-counting use. */
6932 #if ! defined (HAVE_decrement_and_branch_until_zero) && defined (HAVE_decrement_and_branch_on_count)
6933 && (! (add_val == 1 && vtop
6934 && (bl->biv_count == 0
6935 || no_use_except_counting)))
6937 && GET_CODE (comparison_value) == CONST_INT
6938 /* Now do postponed overflow checks on COMPARISON_VAL. */
6939 && ! (((comparison_val - add_val) ^ INTVAL (comparison_value))
6940 & comparison_sign_mask))
6942 /* Register will always be nonnegative, with value
6943 0 on last iteration */
6944 add_adjust = add_val;
6948 else if (add_val == 1 && vtop
6949 && (bl->biv_count == 0
6950 || no_use_except_counting))
6958 if (GET_CODE (comparison) == LE)
6959 add_adjust -= add_val;
6961 /* If the initial value is not zero, or if the comparison
6962 value is not an exact multiple of the increment, then we
6963 can not reverse this loop. */
6964 if (initial_value == const0_rtx
6965 && GET_CODE (comparison_value) == CONST_INT)
6967 if (((unsigned HOST_WIDE_INT) comparison_val % add_val) != 0)
6972 if (! no_use_except_counting || add_val != 1)
6976 final_value = comparison_value;
6978 /* Reset these in case we normalized the initial value
6979 and comparison value above. */
6980 if (GET_CODE (comparison_value) == CONST_INT
6981 && GET_CODE (initial_value) == CONST_INT)
6983 comparison_value = GEN_INT (comparison_val);
6985 = GEN_INT (comparison_val + INTVAL (bl->initial_value));
6987 bl->initial_value = initial_value;
6989 /* Save some info needed to produce the new insns. */
6990 reg = bl->biv->dest_reg;
6991 jump_label = XEXP (SET_SRC (PATTERN (PREV_INSN (loop_end))), 1);
6992 if (jump_label == pc_rtx)
6993 jump_label = XEXP (SET_SRC (PATTERN (PREV_INSN (loop_end))), 2);
6994 new_add_val = GEN_INT (- INTVAL (bl->biv->add_val));
6996 /* Set start_value; if this is not a CONST_INT, we need
6998 Initialize biv to start_value before loop start.
6999 The old initializing insn will be deleted as a
7000 dead store by flow.c. */
7001 if (initial_value == const0_rtx
7002 && GET_CODE (comparison_value) == CONST_INT)
7004 start_value = GEN_INT (comparison_val - add_adjust);
7005 emit_insn_before (gen_move_insn (reg, start_value),
7008 else if (GET_CODE (initial_value) == CONST_INT)
7010 rtx offset = GEN_INT (-INTVAL (initial_value) - add_adjust);
7011 enum machine_mode mode = GET_MODE (reg);
7012 enum insn_code icode
7013 = add_optab->handlers[(int) mode].insn_code;
7014 if (! (*insn_operand_predicate[icode][0]) (reg, mode)
7015 || ! ((*insn_operand_predicate[icode][1])
7016 (comparison_value, mode))
7017 || ! (*insn_operand_predicate[icode][2]) (offset, mode))
7020 = gen_rtx_PLUS (mode, comparison_value, offset);
7021 emit_insn_before ((GEN_FCN (icode)
7022 (reg, comparison_value, offset)),
7024 if (GET_CODE (comparison) == LE)
7025 final_value = gen_rtx_PLUS (mode, comparison_value,
7028 else if (! add_adjust)
7030 enum machine_mode mode = GET_MODE (reg);
7031 enum insn_code icode
7032 = sub_optab->handlers[(int) mode].insn_code;
7033 if (! (*insn_operand_predicate[icode][0]) (reg, mode)
7034 || ! ((*insn_operand_predicate[icode][1])
7035 (comparison_value, mode))
7036 || ! ((*insn_operand_predicate[icode][2])
7037 (initial_value, mode)))
7040 = gen_rtx_MINUS (mode, comparison_value, initial_value);
7041 emit_insn_before ((GEN_FCN (icode)
7042 (reg, comparison_value, initial_value)),
7046 /* We could handle the other cases too, but it'll be
7047 better to have a testcase first. */
7050 /* Add insn to decrement register, and delete insn
7051 that incremented the register. */
7052 p = emit_insn_before (gen_add2_insn (reg, new_add_val),
7054 delete_insn (bl->biv->insn);
7056 /* Update biv info to reflect its new status. */
7058 bl->initial_value = start_value;
7059 bl->biv->add_val = new_add_val;
7061 /* Inc LABEL_NUSES so that delete_insn will
7062 not delete the label. */
7063 LABEL_NUSES (XEXP (jump_label, 0)) ++;
7065 /* Emit an insn after the end of the loop to set the biv's
7066 proper exit value if it is used anywhere outside the loop. */
7067 if ((REGNO_LAST_UID (bl->regno) != INSN_UID (first_compare))
7069 || REGNO_FIRST_UID (bl->regno) != INSN_UID (bl->init_insn))
7070 emit_insn_after (gen_move_insn (reg, final_value),
7073 /* Delete compare/branch at end of loop. */
7074 delete_insn (PREV_INSN (loop_end));
7075 if (compare_and_branch == 2)
7076 delete_insn (first_compare);
7078 /* Add new compare/branch insn at end of loop. */
7080 emit_cmp_insn (reg, const0_rtx, cmp_code, NULL_RTX,
7081 GET_MODE (reg), 0, 0);
7082 emit_jump_insn ((*bcc_gen_fctn[(int) cmp_code])
7083 (XEXP (jump_label, 0)));
7084 tem = gen_sequence ();
7086 emit_jump_insn_before (tem, loop_end);
7090 for (tem = PREV_INSN (loop_end);
7091 tem && GET_CODE (tem) != JUMP_INSN;
7092 tem = PREV_INSN (tem))
7096 JUMP_LABEL (tem) = XEXP (jump_label, 0);
7098 /* Increment of LABEL_NUSES done above. */
7099 /* Register is now always nonnegative,
7100 so add REG_NONNEG note to the branch. */
7101 REG_NOTES (tem) = gen_rtx_EXPR_LIST (REG_NONNEG, NULL_RTX,
7107 /* Mark that this biv has been reversed. Each giv which depends
7108 on this biv, and which is also live past the end of the loop
7109 will have to be fixed up. */
7113 if (loop_dump_stream)
7114 fprintf (loop_dump_stream,
7115 "Reversed loop and added reg_nonneg\n");
7125 /* Verify whether the biv BL appears to be eliminable,
7126 based on the insns in the loop that refer to it.
7127 LOOP_START is the first insn of the loop, and END is the end insn.
7129 If ELIMINATE_P is non-zero, actually do the elimination.
7131 THRESHOLD and INSN_COUNT are from loop_optimize and are used to
7132 determine whether invariant insns should be placed inside or at the
7133 start of the loop. */
7136 maybe_eliminate_biv (bl, loop_start, end, eliminate_p, threshold, insn_count)
7137 struct iv_class *bl;
7141 int threshold, insn_count;
7143 rtx reg = bl->biv->dest_reg;
7146 /* Scan all insns in the loop, stopping if we find one that uses the
7147 biv in a way that we cannot eliminate. */
7149 for (p = loop_start; p != end; p = NEXT_INSN (p))
7151 enum rtx_code code = GET_CODE (p);
7152 rtx where = threshold >= insn_count ? loop_start : p;
7154 if ((code == INSN || code == JUMP_INSN || code == CALL_INSN)
7155 && reg_mentioned_p (reg, PATTERN (p))
7156 && ! maybe_eliminate_biv_1 (PATTERN (p), p, bl, eliminate_p, where))
7158 if (loop_dump_stream)
7159 fprintf (loop_dump_stream,
7160 "Cannot eliminate biv %d: biv used in insn %d.\n",
7161 bl->regno, INSN_UID (p));
7168 if (loop_dump_stream)
7169 fprintf (loop_dump_stream, "biv %d %s eliminated.\n",
7170 bl->regno, eliminate_p ? "was" : "can be");
7177 /* If BL appears in X (part of the pattern of INSN), see if we can
7178 eliminate its use. If so, return 1. If not, return 0.
7180 If BIV does not appear in X, return 1.
7182 If ELIMINATE_P is non-zero, actually do the elimination. WHERE indicates
7183 where extra insns should be added. Depending on how many items have been
7184 moved out of the loop, it will either be before INSN or at the start of
7188 maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
7190 struct iv_class *bl;
7194 enum rtx_code code = GET_CODE (x);
7195 rtx reg = bl->biv->dest_reg;
7196 enum machine_mode mode = GET_MODE (reg);
7197 struct induction *v;
7209 /* If we haven't already been able to do something with this BIV,
7210 we can't eliminate it. */
7216 /* If this sets the BIV, it is not a problem. */
7217 if (SET_DEST (x) == reg)
7220 /* If this is an insn that defines a giv, it is also ok because
7221 it will go away when the giv is reduced. */
7222 for (v = bl->giv; v; v = v->next_iv)
7223 if (v->giv_type == DEST_REG && SET_DEST (x) == v->dest_reg)
7227 if (SET_DEST (x) == cc0_rtx && SET_SRC (x) == reg)
7229 /* Can replace with any giv that was reduced and
7230 that has (MULT_VAL != 0) and (ADD_VAL == 0).
7231 Require a constant for MULT_VAL, so we know it's nonzero.
7232 ??? We disable this optimization to avoid potential
7235 for (v = bl->giv; v; v = v->next_iv)
7236 if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx
7237 && v->add_val == const0_rtx
7238 && ! v->ignore && ! v->maybe_dead && v->always_computable
7242 /* If the giv V had the auto-inc address optimization applied
7243 to it, and INSN occurs between the giv insn and the biv
7244 insn, then we must adjust the value used here.
7245 This is rare, so we don't bother to do so. */
7247 && ((INSN_LUID (v->insn) < INSN_LUID (insn)
7248 && INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
7249 || (INSN_LUID (v->insn) > INSN_LUID (insn)
7250 && INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
7256 /* If the giv has the opposite direction of change,
7257 then reverse the comparison. */
7258 if (INTVAL (v->mult_val) < 0)
7259 new = gen_rtx_COMPARE (GET_MODE (v->new_reg),
7260 const0_rtx, v->new_reg);
7264 /* We can probably test that giv's reduced reg. */
7265 if (validate_change (insn, &SET_SRC (x), new, 0))
7269 /* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0);
7270 replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL).
7271 Require a constant for MULT_VAL, so we know it's nonzero.
7272 ??? Do this only if ADD_VAL is a pointer to avoid a potential
7273 overflow problem. */
7275 for (v = bl->giv; v; v = v->next_iv)
7276 if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx
7277 && ! v->ignore && ! v->maybe_dead && v->always_computable
7279 && (GET_CODE (v->add_val) == SYMBOL_REF
7280 || GET_CODE (v->add_val) == LABEL_REF
7281 || GET_CODE (v->add_val) == CONST
7282 || (GET_CODE (v->add_val) == REG
7283 && REGNO_POINTER_FLAG (REGNO (v->add_val)))))
7285 /* If the giv V had the auto-inc address optimization applied
7286 to it, and INSN occurs between the giv insn and the biv
7287 insn, then we must adjust the value used here.
7288 This is rare, so we don't bother to do so. */
7290 && ((INSN_LUID (v->insn) < INSN_LUID (insn)
7291 && INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
7292 || (INSN_LUID (v->insn) > INSN_LUID (insn)
7293 && INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
7299 /* If the giv has the opposite direction of change,
7300 then reverse the comparison. */
7301 if (INTVAL (v->mult_val) < 0)
7302 new = gen_rtx_COMPARE (VOIDmode, copy_rtx (v->add_val),
7305 new = gen_rtx_COMPARE (VOIDmode, v->new_reg,
7306 copy_rtx (v->add_val));
7308 /* Replace biv with the giv's reduced register. */
7309 update_reg_last_use (v->add_val, insn);
7310 if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0))
7313 /* Insn doesn't support that constant or invariant. Copy it
7314 into a register (it will be a loop invariant.) */
7315 tem = gen_reg_rtx (GET_MODE (v->new_reg));
7317 emit_insn_before (gen_move_insn (tem, copy_rtx (v->add_val)),
7320 /* Substitute the new register for its invariant value in
7321 the compare expression. */
7322 XEXP (new, (INTVAL (v->mult_val) < 0) ? 0 : 1) = tem;
7323 if (validate_change (insn, &SET_SRC (PATTERN (insn)), new, 0))
7332 case GT: case GE: case GTU: case GEU:
7333 case LT: case LE: case LTU: case LEU:
7334 /* See if either argument is the biv. */
7335 if (XEXP (x, 0) == reg)
7336 arg = XEXP (x, 1), arg_operand = 1;
7337 else if (XEXP (x, 1) == reg)
7338 arg = XEXP (x, 0), arg_operand = 0;
7342 if (CONSTANT_P (arg))
7344 /* First try to replace with any giv that has constant positive
7345 mult_val and constant add_val. We might be able to support
7346 negative mult_val, but it seems complex to do it in general. */
7348 for (v = bl->giv; v; v = v->next_iv)
7349 if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
7350 && (GET_CODE (v->add_val) == SYMBOL_REF
7351 || GET_CODE (v->add_val) == LABEL_REF
7352 || GET_CODE (v->add_val) == CONST
7353 || (GET_CODE (v->add_val) == REG
7354 && REGNO_POINTER_FLAG (REGNO (v->add_val))))
7355 && ! v->ignore && ! v->maybe_dead && v->always_computable
7358 /* If the giv V had the auto-inc address optimization applied
7359 to it, and INSN occurs between the giv insn and the biv
7360 insn, then we must adjust the value used here.
7361 This is rare, so we don't bother to do so. */
7363 && ((INSN_LUID (v->insn) < INSN_LUID (insn)
7364 && INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
7365 || (INSN_LUID (v->insn) > INSN_LUID (insn)
7366 && INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
7372 /* Replace biv with the giv's reduced reg. */
7373 XEXP (x, 1-arg_operand) = v->new_reg;
7375 /* If all constants are actually constant integers and
7376 the derived constant can be directly placed in the COMPARE,
7378 if (GET_CODE (arg) == CONST_INT
7379 && GET_CODE (v->mult_val) == CONST_INT
7380 && GET_CODE (v->add_val) == CONST_INT
7381 && validate_change (insn, &XEXP (x, arg_operand),
7382 GEN_INT (INTVAL (arg)
7383 * INTVAL (v->mult_val)
7384 + INTVAL (v->add_val)), 0))
7387 /* Otherwise, load it into a register. */
7388 tem = gen_reg_rtx (mode);
7389 emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where);
7390 if (validate_change (insn, &XEXP (x, arg_operand), tem, 0))
7393 /* If that failed, put back the change we made above. */
7394 XEXP (x, 1-arg_operand) = reg;
7397 /* Look for giv with positive constant mult_val and nonconst add_val.
7398 Insert insns to calculate new compare value.
7399 ??? Turn this off due to possible overflow. */
7401 for (v = bl->giv; v; v = v->next_iv)
7402 if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
7403 && ! v->ignore && ! v->maybe_dead && v->always_computable
7409 /* If the giv V had the auto-inc address optimization applied
7410 to it, and INSN occurs between the giv insn and the biv
7411 insn, then we must adjust the value used here.
7412 This is rare, so we don't bother to do so. */
7414 && ((INSN_LUID (v->insn) < INSN_LUID (insn)
7415 && INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
7416 || (INSN_LUID (v->insn) > INSN_LUID (insn)
7417 && INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
7423 tem = gen_reg_rtx (mode);
7425 /* Replace biv with giv's reduced register. */
7426 validate_change (insn, &XEXP (x, 1 - arg_operand),
7429 /* Compute value to compare against. */
7430 emit_iv_add_mult (arg, v->mult_val, v->add_val, tem, where);
7431 /* Use it in this insn. */
7432 validate_change (insn, &XEXP (x, arg_operand), tem, 1);
7433 if (apply_change_group ())
7437 else if (GET_CODE (arg) == REG || GET_CODE (arg) == MEM)
7439 if (invariant_p (arg) == 1)
7441 /* Look for giv with constant positive mult_val and nonconst
7442 add_val. Insert insns to compute new compare value.
7443 ??? Turn this off due to possible overflow. */
7445 for (v = bl->giv; v; v = v->next_iv)
7446 if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
7447 && ! v->ignore && ! v->maybe_dead && v->always_computable
7453 /* If the giv V had the auto-inc address optimization applied
7454 to it, and INSN occurs between the giv insn and the biv
7455 insn, then we must adjust the value used here.
7456 This is rare, so we don't bother to do so. */
7458 && ((INSN_LUID (v->insn) < INSN_LUID (insn)
7459 && INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
7460 || (INSN_LUID (v->insn) > INSN_LUID (insn)
7461 && INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
7467 tem = gen_reg_rtx (mode);
7469 /* Replace biv with giv's reduced register. */
7470 validate_change (insn, &XEXP (x, 1 - arg_operand),
7473 /* Compute value to compare against. */
7474 emit_iv_add_mult (arg, v->mult_val, v->add_val,
7476 validate_change (insn, &XEXP (x, arg_operand), tem, 1);
7477 if (apply_change_group ())
7482 /* This code has problems. Basically, you can't know when
7483 seeing if we will eliminate BL, whether a particular giv
7484 of ARG will be reduced. If it isn't going to be reduced,
7485 we can't eliminate BL. We can try forcing it to be reduced,
7486 but that can generate poor code.
7488 The problem is that the benefit of reducing TV, below should
7489 be increased if BL can actually be eliminated, but this means
7490 we might have to do a topological sort of the order in which
7491 we try to process biv. It doesn't seem worthwhile to do
7492 this sort of thing now. */
7495 /* Otherwise the reg compared with had better be a biv. */
7496 if (GET_CODE (arg) != REG
7497 || reg_iv_type[REGNO (arg)] != BASIC_INDUCT)
7500 /* Look for a pair of givs, one for each biv,
7501 with identical coefficients. */
7502 for (v = bl->giv; v; v = v->next_iv)
7504 struct induction *tv;
7506 if (v->ignore || v->maybe_dead || v->mode != mode)
7509 for (tv = reg_biv_class[REGNO (arg)]->giv; tv; tv = tv->next_iv)
7510 if (! tv->ignore && ! tv->maybe_dead
7511 && rtx_equal_p (tv->mult_val, v->mult_val)
7512 && rtx_equal_p (tv->add_val, v->add_val)
7513 && tv->mode == mode)
7515 /* If the giv V had the auto-inc address optimization applied
7516 to it, and INSN occurs between the giv insn and the biv
7517 insn, then we must adjust the value used here.
7518 This is rare, so we don't bother to do so. */
7520 && ((INSN_LUID (v->insn) < INSN_LUID (insn)
7521 && INSN_LUID (insn) < INSN_LUID (bl->biv->insn))
7522 || (INSN_LUID (v->insn) > INSN_LUID (insn)
7523 && INSN_LUID (insn) > INSN_LUID (bl->biv->insn))))
7529 /* Replace biv with its giv's reduced reg. */
7530 XEXP (x, 1-arg_operand) = v->new_reg;
7531 /* Replace other operand with the other giv's
7533 XEXP (x, arg_operand) = tv->new_reg;
7540 /* If we get here, the biv can't be eliminated. */
7544 /* If this address is a DEST_ADDR giv, it doesn't matter if the
7545 biv is used in it, since it will be replaced. */
7546 for (v = bl->giv; v; v = v->next_iv)
7547 if (v->giv_type == DEST_ADDR && v->location == &XEXP (x, 0))
7555 /* See if any subexpression fails elimination. */
7556 fmt = GET_RTX_FORMAT (code);
7557 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
7562 if (! maybe_eliminate_biv_1 (XEXP (x, i), insn, bl,
7563 eliminate_p, where))
7568 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7569 if (! maybe_eliminate_biv_1 (XVECEXP (x, i, j), insn, bl,
7570 eliminate_p, where))
7579 /* Return nonzero if the last use of REG
7580 is in an insn following INSN in the same basic block. */
7583 last_use_this_basic_block (reg, insn)
7589 n && GET_CODE (n) != CODE_LABEL && GET_CODE (n) != JUMP_INSN;
7592 if (REGNO_LAST_UID (REGNO (reg)) == INSN_UID (n))
7598 /* Called via `note_stores' to record the initial value of a biv. Here we
7599 just record the location of the set and process it later. */
7602 record_initial (dest, set)
7606 struct iv_class *bl;
7608 if (GET_CODE (dest) != REG
7609 || REGNO (dest) >= max_reg_before_loop
7610 || reg_iv_type[REGNO (dest)] != BASIC_INDUCT)
7613 bl = reg_biv_class[REGNO (dest)];
7615 /* If this is the first set found, record it. */
7616 if (bl->init_insn == 0)
7618 bl->init_insn = note_insn;
7623 /* If any of the registers in X are "old" and currently have a last use earlier
7624 than INSN, update them to have a last use of INSN. Their actual last use
7625 will be the previous insn but it will not have a valid uid_luid so we can't
7629 update_reg_last_use (x, insn)
7633 /* Check for the case where INSN does not have a valid luid. In this case,
7634 there is no need to modify the regno_last_uid, as this can only happen
7635 when code is inserted after the loop_end to set a pseudo's final value,
7636 and hence this insn will never be the last use of x. */
7637 if (GET_CODE (x) == REG && REGNO (x) < max_reg_before_loop
7638 && INSN_UID (insn) < max_uid_for_loop
7639 && uid_luid[REGNO_LAST_UID (REGNO (x))] < uid_luid[INSN_UID (insn)])
7640 REGNO_LAST_UID (REGNO (x)) = INSN_UID (insn);
7644 register char *fmt = GET_RTX_FORMAT (GET_CODE (x));
7645 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
7648 update_reg_last_use (XEXP (x, i), insn);
7649 else if (fmt[i] == 'E')
7650 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7651 update_reg_last_use (XVECEXP (x, i, j), insn);
7656 /* Given a jump insn JUMP, return the condition that will cause it to branch
7657 to its JUMP_LABEL. If the condition cannot be understood, or is an
7658 inequality floating-point comparison which needs to be reversed, 0 will
7661 If EARLIEST is non-zero, it is a pointer to a place where the earliest
7662 insn used in locating the condition was found. If a replacement test
7663 of the condition is desired, it should be placed in front of that
7664 insn and we will be sure that the inputs are still valid.
7666 The condition will be returned in a canonical form to simplify testing by
7667 callers. Specifically:
7669 (1) The code will always be a comparison operation (EQ, NE, GT, etc.).
7670 (2) Both operands will be machine operands; (cc0) will have been replaced.
7671 (3) If an operand is a constant, it will be the second operand.
7672 (4) (LE x const) will be replaced with (LT x <const+1>) and similarly
7673 for GE, GEU, and LEU. */
7676 get_condition (jump, earliest)
7685 int reverse_code = 0;
7686 int did_reverse_condition = 0;
7687 enum machine_mode mode;
7689 /* If this is not a standard conditional jump, we can't parse it. */
7690 if (GET_CODE (jump) != JUMP_INSN
7691 || ! condjump_p (jump) || simplejump_p (jump))
7694 code = GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 0));
7695 mode = GET_MODE (XEXP (SET_SRC (PATTERN (jump)), 0));
7696 op0 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 0);
7697 op1 = XEXP (XEXP (SET_SRC (PATTERN (jump)), 0), 1);
7702 /* If this branches to JUMP_LABEL when the condition is false, reverse
7704 if (GET_CODE (XEXP (SET_SRC (PATTERN (jump)), 2)) == LABEL_REF
7705 && XEXP (XEXP (SET_SRC (PATTERN (jump)), 2), 0) == JUMP_LABEL (jump))
7706 code = reverse_condition (code), did_reverse_condition ^= 1;
7708 /* If we are comparing a register with zero, see if the register is set
7709 in the previous insn to a COMPARE or a comparison operation. Perform
7710 the same tests as a function of STORE_FLAG_VALUE as find_comparison_args
7713 while (GET_RTX_CLASS (code) == '<' && op1 == CONST0_RTX (GET_MODE (op0)))
7715 /* Set non-zero when we find something of interest. */
7719 /* If comparison with cc0, import actual comparison from compare
7723 if ((prev = prev_nonnote_insn (prev)) == 0
7724 || GET_CODE (prev) != INSN
7725 || (set = single_set (prev)) == 0
7726 || SET_DEST (set) != cc0_rtx)
7729 op0 = SET_SRC (set);
7730 op1 = CONST0_RTX (GET_MODE (op0));
7736 /* If this is a COMPARE, pick up the two things being compared. */
7737 if (GET_CODE (op0) == COMPARE)
7739 op1 = XEXP (op0, 1);
7740 op0 = XEXP (op0, 0);
7743 else if (GET_CODE (op0) != REG)
7746 /* Go back to the previous insn. Stop if it is not an INSN. We also
7747 stop if it isn't a single set or if it has a REG_INC note because
7748 we don't want to bother dealing with it. */
7750 if ((prev = prev_nonnote_insn (prev)) == 0
7751 || GET_CODE (prev) != INSN
7752 || FIND_REG_INC_NOTE (prev, 0)
7753 || (set = single_set (prev)) == 0)
7756 /* If this is setting OP0, get what it sets it to if it looks
7758 if (rtx_equal_p (SET_DEST (set), op0))
7760 enum machine_mode inner_mode = GET_MODE (SET_SRC (set));
7762 /* ??? We may not combine comparisons done in a CCmode with
7763 comparisons not done in a CCmode. This is to aid targets
7764 like Alpha that have an IEEE compliant EQ instruction, and
7765 a non-IEEE compliant BEQ instruction. The use of CCmode is
7766 actually artificial, simply to prevent the combination, but
7767 should not affect other platforms.
7769 However, we must allow VOIDmode comparisons to match either
7770 CCmode or non-CCmode comparison, because some ports have
7771 modeless comparisons inside branch patterns.
7773 ??? This mode check should perhaps look more like the mode check
7774 in simplify_comparison in combine. */
7776 if ((GET_CODE (SET_SRC (set)) == COMPARE
7779 && GET_MODE_CLASS (inner_mode) == MODE_INT
7780 && (GET_MODE_BITSIZE (inner_mode)
7781 <= HOST_BITS_PER_WIDE_INT)
7782 && (STORE_FLAG_VALUE
7783 & ((HOST_WIDE_INT) 1
7784 << (GET_MODE_BITSIZE (inner_mode) - 1))))
7785 #ifdef FLOAT_STORE_FLAG_VALUE
7787 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT
7788 && FLOAT_STORE_FLAG_VALUE < 0)
7791 && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<'))
7792 && (((GET_MODE_CLASS (mode) == MODE_CC)
7793 == (GET_MODE_CLASS (inner_mode) == MODE_CC))
7794 || mode == VOIDmode || inner_mode == VOIDmode))
7796 else if (((code == EQ
7798 && (GET_MODE_BITSIZE (inner_mode)
7799 <= HOST_BITS_PER_WIDE_INT)
7800 && GET_MODE_CLASS (inner_mode) == MODE_INT
7801 && (STORE_FLAG_VALUE
7802 & ((HOST_WIDE_INT) 1
7803 << (GET_MODE_BITSIZE (inner_mode) - 1))))
7804 #ifdef FLOAT_STORE_FLAG_VALUE
7806 && GET_MODE_CLASS (inner_mode) == MODE_FLOAT
7807 && FLOAT_STORE_FLAG_VALUE < 0)
7810 && GET_RTX_CLASS (GET_CODE (SET_SRC (set))) == '<'
7811 && (((GET_MODE_CLASS (mode) == MODE_CC)
7812 == (GET_MODE_CLASS (inner_mode) == MODE_CC))
7813 || mode == VOIDmode || inner_mode == VOIDmode))
7816 /* We might have reversed a LT to get a GE here. But this wasn't
7817 actually the comparison of data, so we don't flag that we
7818 have had to reverse the condition. */
7819 did_reverse_condition ^= 1;
7827 else if (reg_set_p (op0, prev))
7828 /* If this sets OP0, but not directly, we have to give up. */
7833 if (GET_RTX_CLASS (GET_CODE (x)) == '<')
7834 code = GET_CODE (x);
7837 code = reverse_condition (code);
7838 did_reverse_condition ^= 1;
7842 op0 = XEXP (x, 0), op1 = XEXP (x, 1);
7848 /* If constant is first, put it last. */
7849 if (CONSTANT_P (op0))
7850 code = swap_condition (code), tem = op0, op0 = op1, op1 = tem;
7852 /* If OP0 is the result of a comparison, we weren't able to find what
7853 was really being compared, so fail. */
7854 if (GET_MODE_CLASS (GET_MODE (op0)) == MODE_CC)
7857 /* Canonicalize any ordered comparison with integers involving equality
7858 if we can do computations in the relevant mode and we do not
7861 if (GET_CODE (op1) == CONST_INT
7862 && GET_MODE (op0) != VOIDmode
7863 && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
7865 HOST_WIDE_INT const_val = INTVAL (op1);
7866 unsigned HOST_WIDE_INT uconst_val = const_val;
7867 unsigned HOST_WIDE_INT max_val
7868 = (unsigned HOST_WIDE_INT) GET_MODE_MASK (GET_MODE (op0));
7873 if ((unsigned HOST_WIDE_INT) const_val != max_val >> 1)
7874 code = LT, op1 = GEN_INT (const_val + 1);
7877 /* When cross-compiling, const_val might be sign-extended from
7878 BITS_PER_WORD to HOST_BITS_PER_WIDE_INT */
7880 if ((HOST_WIDE_INT) (const_val & max_val)
7881 != (((HOST_WIDE_INT) 1
7882 << (GET_MODE_BITSIZE (GET_MODE (op0)) - 1))))
7883 code = GT, op1 = GEN_INT (const_val - 1);
7887 if (uconst_val < max_val)
7888 code = LTU, op1 = GEN_INT (uconst_val + 1);
7892 if (uconst_val != 0)
7893 code = GTU, op1 = GEN_INT (uconst_val - 1);
7901 /* If this was floating-point and we reversed anything other than an
7902 EQ or NE, return zero. */
7903 if (TARGET_FLOAT_FORMAT == IEEE_FLOAT_FORMAT
7904 && did_reverse_condition && code != NE && code != EQ
7906 && GET_MODE_CLASS (GET_MODE (op0)) == MODE_FLOAT)
7910 /* Never return CC0; return zero instead. */
7915 return gen_rtx_fmt_ee (code, VOIDmode, op0, op1);
7918 /* Similar to above routine, except that we also put an invariant last
7919 unless both operands are invariants. */
7922 get_condition_for_loop (x)
7925 rtx comparison = get_condition (x, NULL_PTR);
7928 || ! invariant_p (XEXP (comparison, 0))
7929 || invariant_p (XEXP (comparison, 1)))
7932 return gen_rtx_fmt_ee (swap_condition (GET_CODE (comparison)), VOIDmode,
7933 XEXP (comparison, 1), XEXP (comparison, 0));
7936 #ifdef HAVE_decrement_and_branch_on_count
7937 /* Instrument loop for insertion of bct instruction. We distinguish between
7938 loops with compile-time bounds and those with run-time bounds.
7939 Information from loop_iterations() is used to compute compile-time bounds.
7940 Run-time bounds should use loop preconditioning, but currently ignored.
7944 insert_bct (loop_start, loop_end)
7945 rtx loop_start, loop_end;
7948 unsigned HOST_WIDE_INT n_iterations;
7951 int increment_direction, compare_direction;
7953 /* If the loop condition is <= or >=, the number of iteration
7954 is 1 more than the range of the bounds of the loop. */
7955 int add_iteration = 0;
7957 enum machine_mode loop_var_mode = word_mode;
7959 int loop_num = uid_loop_num [INSN_UID (loop_start)];
7961 /* It's impossible to instrument a competely unrolled loop. */
7962 if (loop_unroll_factor [loop_num] == -1)
7965 /* Make sure that the count register is not in use. */
7966 if (loop_used_count_register [loop_num])
7968 if (loop_dump_stream)
7969 fprintf (loop_dump_stream,
7970 "insert_bct %d: BCT instrumentation failed: count register already in use\n",
7975 /* Make sure that the function has no indirect jumps. */
7976 if (indirect_jump_in_function)
7978 if (loop_dump_stream)
7979 fprintf (loop_dump_stream,
7980 "insert_bct %d: BCT instrumentation failed: indirect jump in function\n",
7985 /* Make sure that the last loop insn is a conditional jump. */
7986 if (GET_CODE (PREV_INSN (loop_end)) != JUMP_INSN
7987 || ! condjump_p (PREV_INSN (loop_end))
7988 || simplejump_p (PREV_INSN (loop_end)))
7990 if (loop_dump_stream)
7991 fprintf (loop_dump_stream,
7992 "insert_bct %d: BCT instrumentation failed: invalid jump at loop end\n",
7997 /* Make sure that the loop does not contain a function call
7998 (the count register might be altered by the called function). */
8001 if (loop_dump_stream)
8002 fprintf (loop_dump_stream,
8003 "insert_bct %d: BCT instrumentation failed: function call in loop\n",
8008 /* Make sure that the loop does not jump via a table.
8009 (the count register might be used to perform the branch on table). */
8010 for (insn = loop_start; insn && insn != loop_end; insn = NEXT_INSN (insn))
8012 if (GET_CODE (insn) == JUMP_INSN
8013 && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
8014 || GET_CODE (PATTERN (insn)) == ADDR_VEC))
8016 if (loop_dump_stream)
8017 fprintf (loop_dump_stream,
8018 "insert_bct %d: BCT instrumentation failed: computed branch in the loop\n",
8024 /* Account for loop unrolling in instrumented iteration count. */
8025 if (loop_unroll_factor [loop_num] > 1)
8026 n_iterations = loop_n_iterations / loop_unroll_factor [loop_num];
8028 n_iterations = loop_n_iterations;
8030 if (n_iterations != 0 && n_iterations < 3)
8032 /* Allow an enclosing outer loop to benefit if possible. */
8033 if (loop_dump_stream)
8034 fprintf (loop_dump_stream,
8035 "insert_bct %d: Too few iterations to benefit from BCT optimization\n",
8040 /* Try to instrument the loop. */
8042 /* Handle the simpler case, where the bounds are known at compile time. */
8043 if (n_iterations > 0)
8045 /* Mark all enclosing loops that they cannot use count register. */
8046 for (i=loop_num; i != -1; i = loop_outer_loop[i])
8047 loop_used_count_register[i] = 1;
8048 instrument_loop_bct (loop_start, loop_end, GEN_INT (n_iterations));
8052 /* Handle the more complex case, that the bounds are NOT known
8053 at compile time. In this case we generate run_time calculation
8054 of the number of iterations. */
8056 if (loop_iteration_var == 0)
8058 if (loop_dump_stream)
8059 fprintf (loop_dump_stream,
8060 "insert_bct %d: BCT Runtime Instrumentation failed: no loop iteration variable found\n",
8065 if (GET_MODE_CLASS (GET_MODE (loop_iteration_var)) != MODE_INT
8066 || GET_MODE_SIZE (GET_MODE (loop_iteration_var)) != UNITS_PER_WORD)
8068 if (loop_dump_stream)
8069 fprintf (loop_dump_stream,
8070 "insert_bct %d: BCT Runtime Instrumentation failed: loop variable not integer\n",
8075 /* With runtime bounds, if the compare is of the form '!=' we give up */
8076 if (loop_comparison_code == NE)
8078 if (loop_dump_stream)
8079 fprintf (loop_dump_stream,
8080 "insert_bct %d: BCT Runtime Instrumentation failed: runtime bounds with != comparison\n",
8084 /* Use common loop preconditioning code instead. */
8088 /* We rely on the existence of run-time guard to ensure that the
8089 loop executes at least once. */
8091 rtx iterations_num_reg;
8093 unsigned HOST_WIDE_INT increment_value_abs
8094 = INTVAL (increment) * increment_direction;
8096 /* make sure that the increment is a power of two, otherwise (an
8097 expensive) divide is needed. */
8098 if (exact_log2 (increment_value_abs) == -1)
8100 if (loop_dump_stream)
8101 fprintf (loop_dump_stream,
8102 "insert_bct: not instrumenting BCT because the increment is not power of 2\n");
8106 /* compute the number of iterations */
8111 /* Again, the number of iterations is calculated by:
8113 ; compare-val - initial-val + (increment -1) + additional-iteration
8114 ; num_iterations = -----------------------------------------------------------------
8117 /* ??? Do we have to call copy_rtx here before passing rtx to
8119 if (compare_direction > 0)
8121 /* <, <= :the loop variable is increasing */
8122 temp_reg = expand_binop (loop_var_mode, sub_optab,
8123 comparison_value, initial_value,
8124 NULL_RTX, 0, OPTAB_LIB_WIDEN);
8128 temp_reg = expand_binop (loop_var_mode, sub_optab,
8129 initial_value, comparison_value,
8130 NULL_RTX, 0, OPTAB_LIB_WIDEN);
8133 if (increment_value_abs - 1 + add_iteration != 0)
8134 temp_reg = expand_binop (loop_var_mode, add_optab, temp_reg,
8135 GEN_INT (increment_value_abs - 1
8137 NULL_RTX, 0, OPTAB_LIB_WIDEN);
8139 if (increment_value_abs != 1)
8141 /* ??? This will generate an expensive divide instruction for
8142 most targets. The original authors apparently expected this
8143 to be a shift, since they test for power-of-2 divisors above,
8144 but just naively generating a divide instruction will not give
8145 a shift. It happens to work for the PowerPC target because
8146 the rs6000.md file has a divide pattern that emits shifts.
8147 It will probably not work for any other target. */
8148 iterations_num_reg = expand_binop (loop_var_mode, sdiv_optab,
8150 GEN_INT (increment_value_abs),
8151 NULL_RTX, 0, OPTAB_LIB_WIDEN);
8154 iterations_num_reg = temp_reg;
8156 sequence = gen_sequence ();
8158 emit_insn_before (sequence, loop_start);
8159 instrument_loop_bct (loop_start, loop_end, iterations_num_reg);
8163 #endif /* Complex case */
8166 /* Instrument loop by inserting a bct in it as follows:
8167 1. A new counter register is created.
8168 2. In the head of the loop the new variable is initialized to the value
8169 passed in the loop_num_iterations parameter.
8170 3. At the end of the loop, comparison of the register with 0 is generated.
8171 The created comparison follows the pattern defined for the
8172 decrement_and_branch_on_count insn, so this insn will be generated.
8173 4. The branch on the old variable are deleted. The compare must remain
8174 because it might be used elsewhere. If the loop-variable or condition
8175 register are used elsewhere, they will be eliminated by flow. */
8178 instrument_loop_bct (loop_start, loop_end, loop_num_iterations)
8179 rtx loop_start, loop_end;
8180 rtx loop_num_iterations;
8186 if (HAVE_decrement_and_branch_on_count)
8188 if (loop_dump_stream)
8190 fputs ("instrument_bct: Inserting BCT (", loop_dump_stream);
8191 if (GET_CODE (loop_num_iterations) == CONST_INT)
8192 fprintf (loop_dump_stream, HOST_WIDE_INT_PRINT_DEC,
8193 INTVAL (loop_num_iterations));
8195 fputs ("runtime", loop_dump_stream);
8196 fputs (" iterations)", loop_dump_stream);
8199 /* Discard original jump to continue loop. Original compare result
8200 may still be live, so it cannot be discarded explicitly. */
8201 delete_insn (PREV_INSN (loop_end));
8203 /* Insert the label which will delimit the start of the loop. */
8204 start_label = gen_label_rtx ();
8205 emit_label_after (start_label, loop_start);
8207 /* Insert initialization of the count register into the loop header. */
8209 counter_reg = gen_reg_rtx (word_mode);
8210 emit_insn (gen_move_insn (counter_reg, loop_num_iterations));
8211 sequence = gen_sequence ();
8213 emit_insn_before (sequence, loop_start);
8215 /* Insert new comparison on the count register instead of the
8216 old one, generating the needed BCT pattern (that will be
8217 later recognized by assembly generation phase). */
8218 emit_jump_insn_before (gen_decrement_and_branch_on_count (counter_reg,
8221 LABEL_NUSES (start_label)++;
8225 #endif /* HAVE_decrement_and_branch_on_count */
8227 /* Scan the function and determine whether it has indirect (computed) jumps.
8229 This is taken mostly from flow.c; similar code exists elsewhere
8230 in the compiler. It may be useful to put this into rtlanal.c. */
8232 indirect_jump_in_function_p (start)
8237 for (insn = start; insn; insn = NEXT_INSN (insn))
8238 if (computed_jump_p (insn))
8244 /* Add MEM to the LOOP_MEMS array, if appropriate. See the
8245 documentation for LOOP_MEMS for the definition of `appropriate'.
8246 This function is called from prescan_loop via for_each_rtx. */
8249 insert_loop_mem (mem, data)
8251 void *data ATTRIBUTE_UNUSED;
8259 switch (GET_CODE (m))
8265 /* We're not interested in the MEM associated with a
8266 CONST_DOUBLE, so there's no need to traverse into this. */
8270 /* This is not a MEM. */
8274 /* See if we've already seen this MEM. */
8275 for (i = 0; i < loop_mems_idx; ++i)
8276 if (rtx_equal_p (m, loop_mems[i].mem))
8278 if (GET_MODE (m) != GET_MODE (loop_mems[i].mem))
8279 /* The modes of the two memory accesses are different. If
8280 this happens, something tricky is going on, and we just
8281 don't optimize accesses to this MEM. */
8282 loop_mems[i].optimize = 0;
8287 /* Resize the array, if necessary. */
8288 if (loop_mems_idx == loop_mems_allocated)
8290 if (loop_mems_allocated != 0)
8291 loop_mems_allocated *= 2;
8293 loop_mems_allocated = 32;
8295 loop_mems = (loop_mem_info*)
8296 xrealloc (loop_mems,
8297 loop_mems_allocated * sizeof (loop_mem_info));
8300 /* Actually insert the MEM. */
8301 loop_mems[loop_mems_idx].mem = m;
8302 /* We can't hoist this MEM out of the loop if it's a BLKmode MEM
8303 because we can't put it in a register. We still store it in the
8304 table, though, so that if we see the same address later, but in a
8305 non-BLK mode, we'll not think we can optimize it at that point. */
8306 loop_mems[loop_mems_idx].optimize = (GET_MODE (m) != BLKmode);
8307 loop_mems[loop_mems_idx].reg = NULL_RTX;
8313 /* Like load_mems, but also ensures that N_TIMES_SET,
8314 MAY_NOT_OPTIMIZE, REG_SINGLE_USAGE, and INSN_COUNT have the correct
8315 values after load_mems. */
8318 load_mems_and_recount_loop_regs_set (scan_start, end, loop_top, start,
8319 reg_single_usage, insn_count)
8324 varray_type reg_single_usage;
8327 int nregs = max_reg_num ();
8329 load_mems (scan_start, end, loop_top, start);
8331 /* Recalculate n_times_set and friends since load_mems may have
8332 created new registers. */
8333 if (max_reg_num () > nregs)
8339 nregs = max_reg_num ();
8341 if ((unsigned) nregs > n_times_set->num_elements)
8343 /* Grow all the arrays. */
8344 VARRAY_GROW (n_times_set, nregs);
8345 VARRAY_GROW (n_times_used, nregs);
8346 VARRAY_GROW (may_not_optimize, nregs);
8347 if (reg_single_usage)
8348 VARRAY_GROW (reg_single_usage, nregs);
8350 /* Clear the arrays */
8351 bzero ((char *) &n_times_set->data, nregs * sizeof (int));
8352 bzero ((char *) &may_not_optimize->data, nregs * sizeof (char));
8353 if (reg_single_usage)
8354 bzero ((char *) ®_single_usage->data, nregs * sizeof (rtx));
8356 count_loop_regs_set (loop_top ? loop_top : start, end,
8357 may_not_optimize, reg_single_usage,
8360 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
8362 VARRAY_CHAR (may_not_optimize, i) = 1;
8363 VARRAY_INT (n_times_set, i) = 1;
8366 #ifdef AVOID_CCMODE_COPIES
8367 /* Don't try to move insns which set CC registers if we should not
8368 create CCmode register copies. */
8369 for (i = max_reg_num () - 1; i >= FIRST_PSEUDO_REGISTER; i--)
8370 if (GET_MODE_CLASS (GET_MODE (regno_reg_rtx[i])) == MODE_CC)
8371 VARRAY_CHAR (may_not_optimize, i) = 1;
8374 /* Set n_times_used for the new registers. */
8375 bcopy ((char *) (&n_times_set->data.i[0] + old_nregs),
8376 (char *) (&n_times_used->data.i[0] + old_nregs),
8377 (nregs - old_nregs) * sizeof (int));
8381 /* Move MEMs into registers for the duration of the loop. SCAN_START
8382 is the first instruction in the loop (as it is executed). The
8383 other parameters are as for next_insn_in_loop. */
8386 load_mems (scan_start, end, loop_top, start)
8392 int maybe_never = 0;
8395 rtx label = NULL_RTX;
8398 if (loop_mems_idx > 0)
8400 /* Nonzero if the next instruction may never be executed. */
8401 int next_maybe_never = 0;
8403 /* Check to see if it's possible that some instructions in the
8404 loop are never executed. */
8405 for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
8406 p != NULL_RTX && !maybe_never;
8407 p = next_insn_in_loop (p, scan_start, end, loop_top))
8409 if (GET_CODE (p) == CODE_LABEL)
8411 else if (GET_CODE (p) == JUMP_INSN
8412 /* If we enter the loop in the middle, and scan
8413 around to the beginning, don't set maybe_never
8414 for that. This must be an unconditional jump,
8415 otherwise the code at the top of the loop might
8416 never be executed. Unconditional jumps are
8417 followed a by barrier then loop end. */
8418 && ! (GET_CODE (p) == JUMP_INSN
8419 && JUMP_LABEL (p) == loop_top
8420 && NEXT_INSN (NEXT_INSN (p)) == end
8421 && simplejump_p (p)))
8423 if (!condjump_p (p))
8424 /* Something complicated. */
8427 /* If there are any more instructions in the loop, they
8428 might not be reached. */
8429 next_maybe_never = 1;
8431 else if (next_maybe_never)
8435 /* Actually move the MEMs. */
8436 for (i = 0; i < loop_mems_idx; ++i)
8441 rtx mem = loop_mems[i].mem;
8443 if (MEM_VOLATILE_P (mem)
8444 || invariant_p (XEXP (mem, 0)) != 1)
8445 /* There's no telling whether or not MEM is modified. */
8446 loop_mems[i].optimize = 0;
8448 /* Go through the MEMs written to in the loop to see if this
8449 one is aliased by one of them. */
8450 for (j = 0; j < loop_store_mems_idx; ++j)
8452 if (rtx_equal_p (mem, loop_store_mems[j]))
8454 else if (true_dependence (loop_store_mems[j], VOIDmode,
8457 /* MEM is indeed aliased by this store. */
8458 loop_mems[i].optimize = 0;
8463 /* If this MEM is written to, we must be sure that there
8464 are no reads from another MEM that aliases this one. */
8465 if (loop_mems[i].optimize && written)
8469 for (j = 0; j < loop_mems_idx; ++j)
8473 else if (true_dependence (mem,
8478 /* It's not safe to hoist loop_mems[i] out of
8479 the loop because writes to it might not be
8480 seen by reads from loop_mems[j]. */
8481 loop_mems[i].optimize = 0;
8487 if (maybe_never && may_trap_p (mem))
8488 /* We can't access the MEM outside the loop; it might
8489 cause a trap that wouldn't have happened otherwise. */
8490 loop_mems[i].optimize = 0;
8492 if (!loop_mems[i].optimize)
8493 /* We thought we were going to lift this MEM out of the
8494 loop, but later discovered that we could not. */
8497 /* Allocate a pseudo for this MEM. We set REG_USERVAR_P in
8498 order to keep scan_loop from moving stores to this MEM
8499 out of the loop just because this REG is neither a
8500 user-variable nor used in the loop test. */
8501 reg = gen_reg_rtx (GET_MODE (mem));
8502 REG_USERVAR_P (reg) = 1;
8503 loop_mems[i].reg = reg;
8505 /* Now, replace all references to the MEM with the
8506 corresponding pesudos. */
8507 for (p = next_insn_in_loop (scan_start, scan_start, end, loop_top);
8509 p = next_insn_in_loop (p, scan_start, end, loop_top))
8514 for_each_rtx (&p, replace_loop_mem, &ri);
8517 if (!apply_change_group ())
8518 /* We couldn't replace all occurrences of the MEM. */
8519 loop_mems[i].optimize = 0;
8524 /* Load the memory immediately before START, which is
8525 the NOTE_LOOP_BEG. */
8526 set = gen_rtx_SET (GET_MODE (reg), reg, mem);
8527 emit_insn_before (set, start);
8531 if (label == NULL_RTX)
8533 /* We must compute the former
8534 right-after-the-end label before we insert
8536 end_label = next_label (end);
8537 label = gen_label_rtx ();
8538 emit_label_after (label, end);
8541 /* Store the memory immediately after END, which is
8542 the NOTE_LOOP_END. */
8543 set = gen_rtx_SET (GET_MODE (reg), copy_rtx (mem), reg);
8544 emit_insn_after (set, label);
8547 if (loop_dump_stream)
8549 fprintf (loop_dump_stream, "Hoisted regno %d %s from ",
8550 REGNO (reg), (written ? "r/w" : "r/o"));
8551 print_rtl (loop_dump_stream, mem);
8552 fputc ('\n', loop_dump_stream);
8558 if (label != NULL_RTX)
8560 /* Now, we need to replace all references to the previous exit
8561 label with the new one. */
8566 for (p = start; p != end; p = NEXT_INSN (p))
8568 for_each_rtx (&p, replace_label, &rr);
8570 /* If this is a JUMP_INSN, then we also need to fix the JUMP_LABEL
8571 field. This is not handled by for_each_rtx because it doesn't
8572 handle unprinted ('0') fields. We need to update JUMP_LABEL
8573 because the immediately following unroll pass will use it.
8574 replace_label would not work anyways, because that only handles
8576 if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p) == end_label)
8577 JUMP_LABEL (p) = label;
8582 /* Replace MEM with its associated pseudo register. This function is
8583 called from load_mems via for_each_rtx. DATA is actually an
8584 rtx_and_int * describing the instruction currently being scanned
8585 and the MEM we are currently replacing. */
8588 replace_loop_mem (mem, data)
8600 switch (GET_CODE (m))
8606 /* We're not interested in the MEM associated with a
8607 CONST_DOUBLE, so there's no need to traverse into one. */
8611 /* This is not a MEM. */
8615 ri = (rtx_and_int*) data;
8618 if (!rtx_equal_p (loop_mems[i].mem, m))
8619 /* This is not the MEM we are currently replacing. */
8624 /* Actually replace the MEM. */
8625 validate_change (insn, mem, loop_mems[i].reg, 1);
8630 /* Replace occurrences of the old exit label for the loop with the new
8631 one. DATA is an rtx_pair containing the old and new labels,
8635 replace_label (x, data)
8640 rtx old_label = ((rtx_pair*) data)->r1;
8641 rtx new_label = ((rtx_pair*) data)->r2;
8646 if (GET_CODE (l) != LABEL_REF)
8649 if (XEXP (l, 0) != old_label)
8652 XEXP (l, 0) = new_label;
8653 ++LABEL_NUSES (new_label);
8654 --LABEL_NUSES (old_label);