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[official-gcc.git] / gcc / lra-coalesce.c
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1 /* Coalesce spilled pseudos.
2 Copyright (C) 2010-2014 Free Software Foundation, Inc.
3 Contributed by Vladimir Makarov <vmakarov@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
22 /* This file contains a pass making some simple RTL code
23 transformations by coalescing pseudos to remove some move insns.
25 Spilling pseudos in LRA can create memory-memory moves. We should
26 remove potential memory-memory moves before the next constraint
27 pass because the constraint pass will generate additional insns for
28 such moves and all these insns will be hard to remove afterwards.
30 Here we coalesce only spilled pseudos. Coalescing non-spilled
31 pseudos (with different hard regs) might result in spilling
32 additional pseudos because of possible conflicts with other
33 non-spilled pseudos and, as a consequence, in more constraint
34 passes and even LRA infinite cycling. Trivial the same hard
35 register moves will be removed by subsequent compiler passes.
37 We don't coalesce special reload pseudos. It complicates LRA code
38 a lot without visible generated code improvement.
40 The pseudo live-ranges are used to find conflicting pseudos during
41 coalescing.
43 Most frequently executed moves is tried to be coalesced first. */
45 #include "config.h"
46 #include "system.h"
47 #include "coretypes.h"
48 #include "tm.h"
49 #include "rtl.h"
50 #include "tm_p.h"
51 #include "insn-config.h"
52 #include "recog.h"
53 #include "output.h"
54 #include "regs.h"
55 #include "hard-reg-set.h"
56 #include "flags.h"
57 #include "hashtab.h"
58 #include "hash-set.h"
59 #include "vec.h"
60 #include "machmode.h"
61 #include "input.h"
62 #include "function.h"
63 #include "expr.h"
64 #include "predict.h"
65 #include "dominance.h"
66 #include "cfg.h"
67 #include "basic-block.h"
68 #include "except.h"
69 #include "timevar.h"
70 #include "ira.h"
71 #include "lra-int.h"
72 #include "df.h"
74 /* Arrays whose elements represent the first and the next pseudo
75 (regno) in the coalesced pseudos group to which given pseudo (its
76 regno is the index) belongs. The next of the last pseudo in the
77 group refers to the first pseudo in the group, in other words the
78 group is represented by a cyclic list. */
79 static int *first_coalesced_pseudo, *next_coalesced_pseudo;
81 /* The function is used to sort moves according to their execution
82 frequencies. */
83 static int
84 move_freq_compare_func (const void *v1p, const void *v2p)
86 rtx_insn *mv1 = *(rtx_insn * const *) v1p;
87 rtx_insn *mv2 = *(rtx_insn * const *) v2p;
88 int pri1, pri2;
90 pri1 = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv1));
91 pri2 = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv2));
92 if (pri2 - pri1)
93 return pri2 - pri1;
95 /* If frequencies are equal, sort by moves, so that the results of
96 qsort leave nothing to chance. */
97 return (int) INSN_UID (mv1) - (int) INSN_UID (mv2);
100 /* Pseudos which go away after coalescing. */
101 static bitmap_head coalesced_pseudos_bitmap;
103 /* Merge two sets of coalesced pseudos given correspondingly by
104 pseudos REGNO1 and REGNO2 (more accurately merging REGNO2 group
105 into REGNO1 group). Set up COALESCED_PSEUDOS_BITMAP. */
106 static void
107 merge_pseudos (int regno1, int regno2)
109 int regno, first, first2, last, next;
111 first = first_coalesced_pseudo[regno1];
112 if ((first2 = first_coalesced_pseudo[regno2]) == first)
113 return;
114 for (last = regno2, regno = next_coalesced_pseudo[regno2];;
115 regno = next_coalesced_pseudo[regno])
117 first_coalesced_pseudo[regno] = first;
118 bitmap_set_bit (&coalesced_pseudos_bitmap, regno);
119 if (regno == regno2)
120 break;
121 last = regno;
123 next = next_coalesced_pseudo[first];
124 next_coalesced_pseudo[first] = regno2;
125 next_coalesced_pseudo[last] = next;
126 lra_reg_info[first].live_ranges
127 = (lra_merge_live_ranges
128 (lra_reg_info[first].live_ranges,
129 lra_copy_live_range_list (lra_reg_info[first2].live_ranges)));
130 if (GET_MODE_SIZE (lra_reg_info[first].biggest_mode)
131 < GET_MODE_SIZE (lra_reg_info[first2].biggest_mode))
132 lra_reg_info[first].biggest_mode = lra_reg_info[first2].biggest_mode;
135 /* Change pseudos in *LOC on their coalescing group
136 representatives. */
137 static bool
138 substitute (rtx *loc)
140 int i, regno;
141 const char *fmt;
142 enum rtx_code code;
143 bool res;
145 if (*loc == NULL_RTX)
146 return false;
147 code = GET_CODE (*loc);
148 if (code == REG)
150 regno = REGNO (*loc);
151 if (regno < FIRST_PSEUDO_REGISTER
152 || first_coalesced_pseudo[regno] == regno)
153 return false;
154 *loc = regno_reg_rtx[first_coalesced_pseudo[regno]];
155 return true;
158 res = false;
159 fmt = GET_RTX_FORMAT (code);
160 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
162 if (fmt[i] == 'e')
164 if (substitute (&XEXP (*loc, i)))
165 res = true;
167 else if (fmt[i] == 'E')
169 int j;
171 for (j = XVECLEN (*loc, i) - 1; j >= 0; j--)
172 if (substitute (&XVECEXP (*loc, i, j)))
173 res = true;
176 return res;
179 /* Specialize "substitute" for use on an insn. This can't change
180 the insn ptr, just the contents of the insn. */
182 static bool
183 substitute_within_insn (rtx_insn *insn)
185 rtx loc = insn;
186 return substitute (&loc);
189 /* The current iteration (1, 2, ...) of the coalescing pass. */
190 int lra_coalesce_iter;
192 /* Return true if the move involving REGNO1 and REGNO2 is a potential
193 memory-memory move. */
194 static bool
195 mem_move_p (int regno1, int regno2)
197 return reg_renumber[regno1] < 0 && reg_renumber[regno2] < 0;
200 /* Pseudos used instead of the coalesced pseudos. */
201 static bitmap_head used_pseudos_bitmap;
203 /* Set up USED_PSEUDOS_BITMAP, and update LR_BITMAP (a BB live info
204 bitmap). */
205 static void
206 update_live_info (bitmap lr_bitmap)
208 unsigned int j;
209 bitmap_iterator bi;
211 bitmap_clear (&used_pseudos_bitmap);
212 EXECUTE_IF_AND_IN_BITMAP (&coalesced_pseudos_bitmap, lr_bitmap,
213 FIRST_PSEUDO_REGISTER, j, bi)
214 bitmap_set_bit (&used_pseudos_bitmap, first_coalesced_pseudo[j]);
215 if (! bitmap_empty_p (&used_pseudos_bitmap))
217 bitmap_and_compl_into (lr_bitmap, &coalesced_pseudos_bitmap);
218 bitmap_ior_into (lr_bitmap, &used_pseudos_bitmap);
222 /* Return true if pseudo REGNO can be potentially coalesced. */
223 static bool
224 coalescable_pseudo_p (int regno)
226 lra_assert (regno >= FIRST_PSEUDO_REGISTER);
227 return (/* We don't want to coalesce regnos with equivalences, at
228 least without updating this info. */
229 ira_reg_equiv[regno].constant == NULL_RTX
230 && ira_reg_equiv[regno].memory == NULL_RTX
231 && ira_reg_equiv[regno].invariant == NULL_RTX);
234 /* The major function for aggressive pseudo coalescing of moves only
235 if the both pseudos were spilled and not special reload pseudos. */
236 bool
237 lra_coalesce (void)
239 basic_block bb;
240 rtx_insn *mv, *insn, *next, **sorted_moves;
241 rtx set;
242 int i, mv_num, sregno, dregno;
243 unsigned int regno;
244 int coalesced_moves;
245 int max_regno = max_reg_num ();
246 bitmap_head involved_insns_bitmap;
247 bitmap_head result_pseudo_vals_bitmap;
248 bitmap_iterator bi;
250 timevar_push (TV_LRA_COALESCE);
252 if (lra_dump_file != NULL)
253 fprintf (lra_dump_file,
254 "\n********** Pseudos coalescing #%d: **********\n\n",
255 ++lra_coalesce_iter);
256 first_coalesced_pseudo = XNEWVEC (int, max_regno);
257 next_coalesced_pseudo = XNEWVEC (int, max_regno);
258 for (i = 0; i < max_regno; i++)
259 first_coalesced_pseudo[i] = next_coalesced_pseudo[i] = i;
260 sorted_moves = XNEWVEC (rtx_insn *, get_max_uid ());
261 mv_num = 0;
262 /* Collect moves. */
263 coalesced_moves = 0;
264 FOR_EACH_BB_FN (bb, cfun)
266 FOR_BB_INSNS_SAFE (bb, insn, next)
267 if (INSN_P (insn)
268 && (set = single_set (insn)) != NULL_RTX
269 && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set))
270 && (sregno = REGNO (SET_SRC (set))) >= FIRST_PSEUDO_REGISTER
271 && (dregno = REGNO (SET_DEST (set))) >= FIRST_PSEUDO_REGISTER
272 && mem_move_p (sregno, dregno)
273 && coalescable_pseudo_p (sregno) && coalescable_pseudo_p (dregno)
274 && ! side_effects_p (set)
275 && !(lra_intersected_live_ranges_p
276 (lra_reg_info[sregno].live_ranges,
277 lra_reg_info[dregno].live_ranges)))
278 sorted_moves[mv_num++] = insn;
280 qsort (sorted_moves, mv_num, sizeof (rtx), move_freq_compare_func);
281 /* Coalesced copies, most frequently executed first. */
282 bitmap_initialize (&coalesced_pseudos_bitmap, &reg_obstack);
283 bitmap_initialize (&involved_insns_bitmap, &reg_obstack);
284 for (i = 0; i < mv_num; i++)
286 mv = sorted_moves[i];
287 set = single_set (mv);
288 lra_assert (set != NULL && REG_P (SET_SRC (set))
289 && REG_P (SET_DEST (set)));
290 sregno = REGNO (SET_SRC (set));
291 dregno = REGNO (SET_DEST (set));
292 if (first_coalesced_pseudo[sregno] == first_coalesced_pseudo[dregno])
294 coalesced_moves++;
295 if (lra_dump_file != NULL)
296 fprintf
297 (lra_dump_file, " Coalescing move %i:r%d-r%d (freq=%d)\n",
298 INSN_UID (mv), sregno, dregno,
299 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv)));
300 /* We updated involved_insns_bitmap when doing the merge. */
302 else if (!(lra_intersected_live_ranges_p
303 (lra_reg_info[first_coalesced_pseudo[sregno]].live_ranges,
304 lra_reg_info[first_coalesced_pseudo[dregno]].live_ranges)))
306 coalesced_moves++;
307 if (lra_dump_file != NULL)
308 fprintf
309 (lra_dump_file,
310 " Coalescing move %i:r%d(%d)-r%d(%d) (freq=%d)\n",
311 INSN_UID (mv), sregno, ORIGINAL_REGNO (SET_SRC (set)),
312 dregno, ORIGINAL_REGNO (SET_DEST (set)),
313 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv)));
314 bitmap_ior_into (&involved_insns_bitmap,
315 &lra_reg_info[sregno].insn_bitmap);
316 bitmap_ior_into (&involved_insns_bitmap,
317 &lra_reg_info[dregno].insn_bitmap);
318 merge_pseudos (sregno, dregno);
321 bitmap_initialize (&used_pseudos_bitmap, &reg_obstack);
322 FOR_EACH_BB_FN (bb, cfun)
324 update_live_info (df_get_live_in (bb));
325 update_live_info (df_get_live_out (bb));
326 FOR_BB_INSNS_SAFE (bb, insn, next)
327 if (INSN_P (insn)
328 && bitmap_bit_p (&involved_insns_bitmap, INSN_UID (insn)))
330 if (! substitute_within_insn (insn))
331 continue;
332 lra_update_insn_regno_info (insn);
333 if ((set = single_set (insn)) != NULL_RTX && set_noop_p (set))
335 /* Coalesced move. */
336 if (lra_dump_file != NULL)
337 fprintf (lra_dump_file, " Removing move %i (freq=%d)\n",
338 INSN_UID (insn),
339 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (insn)));
340 lra_set_insn_deleted (insn);
344 /* If we have situation after inheritance pass:
346 r1 <- ... insn originally setting p1
347 i1 <- r1 setting inheritance i1 from reload r1
349 ... <- ... p2 ... dead p2
351 p1 <- i1
352 r2 <- i1
353 ...<- ... r2 ...
355 And we are coalescing p1 and p2 using p1. In this case i1 and p1
356 should have different values, otherwise they can get the same
357 hard reg and this is wrong for insn using p2 before coalescing.
358 So invalidate such inheritance pseudo values. */
359 bitmap_initialize (&result_pseudo_vals_bitmap, &reg_obstack);
360 EXECUTE_IF_SET_IN_BITMAP (&coalesced_pseudos_bitmap, 0, regno, bi)
361 bitmap_set_bit (&result_pseudo_vals_bitmap,
362 lra_reg_info[first_coalesced_pseudo[regno]].val);
363 EXECUTE_IF_SET_IN_BITMAP (&lra_inheritance_pseudos, 0, regno, bi)
364 if (bitmap_bit_p (&result_pseudo_vals_bitmap, lra_reg_info[regno].val))
366 lra_set_regno_unique_value (regno);
367 if (lra_dump_file != NULL)
368 fprintf (lra_dump_file,
369 " Make unique value for inheritance r%d\n", regno);
371 bitmap_clear (&result_pseudo_vals_bitmap);
372 bitmap_clear (&used_pseudos_bitmap);
373 bitmap_clear (&involved_insns_bitmap);
374 bitmap_clear (&coalesced_pseudos_bitmap);
375 if (lra_dump_file != NULL && coalesced_moves != 0)
376 fprintf (lra_dump_file, "Coalesced Moves = %d\n", coalesced_moves);
377 free (sorted_moves);
378 free (next_coalesced_pseudo);
379 free (first_coalesced_pseudo);
380 timevar_pop (TV_LRA_COALESCE);
381 return coalesced_moves != 0;