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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 "function.h"
58 #include "expr.h"
59 #include "basic-block.h"
60 #include "except.h"
61 #include "timevar.h"
62 #include "ira.h"
63 #include "lra-int.h"
64 #include "df.h"
66 /* Arrays whose elements represent the first and the next pseudo
67 (regno) in the coalesced pseudos group to which given pseudo (its
68 regno is the index) belongs. The next of the last pseudo in the
69 group refers to the first pseudo in the group, in other words the
70 group is represented by a cyclic list. */
71 static int *first_coalesced_pseudo, *next_coalesced_pseudo;
73 /* The function is used to sort moves according to their execution
74 frequencies. */
75 static int
76 move_freq_compare_func (const void *v1p, const void *v2p)
78 rtx mv1 = *(const rtx *) v1p;
79 rtx mv2 = *(const rtx *) v2p;
80 int pri1, pri2;
82 pri1 = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv1));
83 pri2 = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv2));
84 if (pri2 - pri1)
85 return pri2 - pri1;
87 /* If frequencies are equal, sort by moves, so that the results of
88 qsort leave nothing to chance. */
89 return (int) INSN_UID (mv1) - (int) INSN_UID (mv2);
92 /* Pseudos which go away after coalescing. */
93 static bitmap_head coalesced_pseudos_bitmap;
95 /* Merge two sets of coalesced pseudos given correspondingly by
96 pseudos REGNO1 and REGNO2 (more accurately merging REGNO2 group
97 into REGNO1 group). Set up COALESCED_PSEUDOS_BITMAP. */
98 static void
99 merge_pseudos (int regno1, int regno2)
101 int regno, first, first2, last, next;
103 first = first_coalesced_pseudo[regno1];
104 if ((first2 = first_coalesced_pseudo[regno2]) == first)
105 return;
106 for (last = regno2, regno = next_coalesced_pseudo[regno2];;
107 regno = next_coalesced_pseudo[regno])
109 first_coalesced_pseudo[regno] = first;
110 bitmap_set_bit (&coalesced_pseudos_bitmap, regno);
111 if (regno == regno2)
112 break;
113 last = regno;
115 next = next_coalesced_pseudo[first];
116 next_coalesced_pseudo[first] = regno2;
117 next_coalesced_pseudo[last] = next;
118 lra_reg_info[first].live_ranges
119 = (lra_merge_live_ranges
120 (lra_reg_info[first].live_ranges,
121 lra_copy_live_range_list (lra_reg_info[first2].live_ranges)));
122 if (GET_MODE_SIZE (lra_reg_info[first].biggest_mode)
123 < GET_MODE_SIZE (lra_reg_info[first2].biggest_mode))
124 lra_reg_info[first].biggest_mode = lra_reg_info[first2].biggest_mode;
127 /* Change pseudos in *LOC on their coalescing group
128 representatives. */
129 static bool
130 substitute (rtx *loc)
132 int i, regno;
133 const char *fmt;
134 enum rtx_code code;
135 bool res;
137 if (*loc == NULL_RTX)
138 return false;
139 code = GET_CODE (*loc);
140 if (code == REG)
142 regno = REGNO (*loc);
143 if (regno < FIRST_PSEUDO_REGISTER
144 || first_coalesced_pseudo[regno] == regno)
145 return false;
146 *loc = regno_reg_rtx[first_coalesced_pseudo[regno]];
147 return true;
150 res = false;
151 fmt = GET_RTX_FORMAT (code);
152 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
154 if (fmt[i] == 'e')
156 if (substitute (&XEXP (*loc, i)))
157 res = true;
159 else if (fmt[i] == 'E')
161 int j;
163 for (j = XVECLEN (*loc, i) - 1; j >= 0; j--)
164 if (substitute (&XVECEXP (*loc, i, j)))
165 res = true;
168 return res;
171 /* The current iteration (1, 2, ...) of the coalescing pass. */
172 int lra_coalesce_iter;
174 /* Return true if the move involving REGNO1 and REGNO2 is a potential
175 memory-memory move. */
176 static bool
177 mem_move_p (int regno1, int regno2)
179 return reg_renumber[regno1] < 0 && reg_renumber[regno2] < 0;
182 /* Pseudos used instead of the coalesced pseudos. */
183 static bitmap_head used_pseudos_bitmap;
185 /* Set up USED_PSEUDOS_BITMAP, and update LR_BITMAP (a BB live info
186 bitmap). */
187 static void
188 update_live_info (bitmap lr_bitmap)
190 unsigned int j;
191 bitmap_iterator bi;
193 bitmap_clear (&used_pseudos_bitmap);
194 EXECUTE_IF_AND_IN_BITMAP (&coalesced_pseudos_bitmap, lr_bitmap,
195 FIRST_PSEUDO_REGISTER, j, bi)
196 bitmap_set_bit (&used_pseudos_bitmap, first_coalesced_pseudo[j]);
197 if (! bitmap_empty_p (&used_pseudos_bitmap))
199 bitmap_and_compl_into (lr_bitmap, &coalesced_pseudos_bitmap);
200 bitmap_ior_into (lr_bitmap, &used_pseudos_bitmap);
204 /* Return true if pseudo REGNO can be potentially coalesced. */
205 static bool
206 coalescable_pseudo_p (int regno)
208 lra_assert (regno >= FIRST_PSEUDO_REGISTER);
209 return (/* We don't want to coalesce regnos with equivalences, at
210 least without updating this info. */
211 ira_reg_equiv[regno].constant == NULL_RTX
212 && ira_reg_equiv[regno].memory == NULL_RTX
213 && ira_reg_equiv[regno].invariant == NULL_RTX);
216 /* The major function for aggressive pseudo coalescing of moves only
217 if the both pseudos were spilled and not special reload pseudos. */
218 bool
219 lra_coalesce (void)
221 basic_block bb;
222 rtx mv, set, insn, next, *sorted_moves;
223 int i, mv_num, sregno, dregno;
224 unsigned int regno;
225 int coalesced_moves;
226 int max_regno = max_reg_num ();
227 bitmap_head involved_insns_bitmap;
228 bitmap_head result_pseudo_vals_bitmap;
229 bitmap_iterator bi;
231 timevar_push (TV_LRA_COALESCE);
233 if (lra_dump_file != NULL)
234 fprintf (lra_dump_file,
235 "\n********** Pseudos coalescing #%d: **********\n\n",
236 ++lra_coalesce_iter);
237 first_coalesced_pseudo = XNEWVEC (int, max_regno);
238 next_coalesced_pseudo = XNEWVEC (int, max_regno);
239 for (i = 0; i < max_regno; i++)
240 first_coalesced_pseudo[i] = next_coalesced_pseudo[i] = i;
241 sorted_moves = XNEWVEC (rtx, get_max_uid ());
242 mv_num = 0;
243 /* Collect moves. */
244 coalesced_moves = 0;
245 FOR_EACH_BB_FN (bb, cfun)
247 FOR_BB_INSNS_SAFE (bb, insn, next)
248 if (INSN_P (insn)
249 && (set = single_set (insn)) != NULL_RTX
250 && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set))
251 && (sregno = REGNO (SET_SRC (set))) >= FIRST_PSEUDO_REGISTER
252 && (dregno = REGNO (SET_DEST (set))) >= FIRST_PSEUDO_REGISTER
253 && mem_move_p (sregno, dregno)
254 && coalescable_pseudo_p (sregno) && coalescable_pseudo_p (dregno)
255 && ! side_effects_p (set)
256 && !(lra_intersected_live_ranges_p
257 (lra_reg_info[sregno].live_ranges,
258 lra_reg_info[dregno].live_ranges)))
259 sorted_moves[mv_num++] = insn;
261 qsort (sorted_moves, mv_num, sizeof (rtx), move_freq_compare_func);
262 /* Coalesced copies, most frequently executed first. */
263 bitmap_initialize (&coalesced_pseudos_bitmap, &reg_obstack);
264 bitmap_initialize (&involved_insns_bitmap, &reg_obstack);
265 for (i = 0; i < mv_num; i++)
267 mv = sorted_moves[i];
268 set = single_set (mv);
269 lra_assert (set != NULL && REG_P (SET_SRC (set))
270 && REG_P (SET_DEST (set)));
271 sregno = REGNO (SET_SRC (set));
272 dregno = REGNO (SET_DEST (set));
273 if (first_coalesced_pseudo[sregno] == first_coalesced_pseudo[dregno])
275 coalesced_moves++;
276 if (lra_dump_file != NULL)
277 fprintf
278 (lra_dump_file, " Coalescing move %i:r%d-r%d (freq=%d)\n",
279 INSN_UID (mv), sregno, dregno,
280 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv)));
281 /* We updated involved_insns_bitmap when doing the merge. */
283 else if (!(lra_intersected_live_ranges_p
284 (lra_reg_info[first_coalesced_pseudo[sregno]].live_ranges,
285 lra_reg_info[first_coalesced_pseudo[dregno]].live_ranges)))
287 coalesced_moves++;
288 if (lra_dump_file != NULL)
289 fprintf
290 (lra_dump_file,
291 " Coalescing move %i:r%d(%d)-r%d(%d) (freq=%d)\n",
292 INSN_UID (mv), sregno, ORIGINAL_REGNO (SET_SRC (set)),
293 dregno, ORIGINAL_REGNO (SET_DEST (set)),
294 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv)));
295 bitmap_ior_into (&involved_insns_bitmap,
296 &lra_reg_info[sregno].insn_bitmap);
297 bitmap_ior_into (&involved_insns_bitmap,
298 &lra_reg_info[dregno].insn_bitmap);
299 merge_pseudos (sregno, dregno);
302 bitmap_initialize (&used_pseudos_bitmap, &reg_obstack);
303 FOR_EACH_BB_FN (bb, cfun)
305 update_live_info (df_get_live_in (bb));
306 update_live_info (df_get_live_out (bb));
307 FOR_BB_INSNS_SAFE (bb, insn, next)
308 if (INSN_P (insn)
309 && bitmap_bit_p (&involved_insns_bitmap, INSN_UID (insn)))
311 if (! substitute (&insn))
312 continue;
313 lra_update_insn_regno_info (insn);
314 if ((set = single_set (insn)) != NULL_RTX && set_noop_p (set))
316 /* Coalesced move. */
317 if (lra_dump_file != NULL)
318 fprintf (lra_dump_file, " Removing move %i (freq=%d)\n",
319 INSN_UID (insn),
320 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (insn)));
321 lra_set_insn_deleted (insn);
325 /* If we have situation after inheritance pass:
327 r1 <- ... insn originally setting p1
328 i1 <- r1 setting inheritance i1 from reload r1
330 ... <- ... p2 ... dead p2
332 p1 <- i1
333 r2 <- i1
334 ...<- ... r2 ...
336 And we are coalescing p1 and p2 using p1. In this case i1 and p1
337 should have different values, otherwise they can get the same
338 hard reg and this is wrong for insn using p2 before coalescing.
339 So invalidate such inheritance pseudo values. */
340 bitmap_initialize (&result_pseudo_vals_bitmap, &reg_obstack);
341 EXECUTE_IF_SET_IN_BITMAP (&coalesced_pseudos_bitmap, 0, regno, bi)
342 bitmap_set_bit (&result_pseudo_vals_bitmap,
343 lra_reg_info[first_coalesced_pseudo[regno]].val);
344 EXECUTE_IF_SET_IN_BITMAP (&lra_inheritance_pseudos, 0, regno, bi)
345 if (bitmap_bit_p (&result_pseudo_vals_bitmap, lra_reg_info[regno].val))
347 lra_set_regno_unique_value (regno);
348 if (lra_dump_file != NULL)
349 fprintf (lra_dump_file,
350 " Make unique value for inheritance r%d\n", regno);
352 bitmap_clear (&result_pseudo_vals_bitmap);
353 bitmap_clear (&used_pseudos_bitmap);
354 bitmap_clear (&involved_insns_bitmap);
355 bitmap_clear (&coalesced_pseudos_bitmap);
356 if (lra_dump_file != NULL && coalesced_moves != 0)
357 fprintf (lra_dump_file, "Coalesced Moves = %d\n", coalesced_moves);
358 free (sorted_moves);
359 free (next_coalesced_pseudo);
360 free (first_coalesced_pseudo);
361 timevar_pop (TV_LRA_COALESCE);
362 return coalesced_moves != 0;