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55a2c322 | 1 | /* Coalesce spilled pseudos. |
818ab71a | 2 | Copyright (C) 2010-2016 Free Software Foundation, Inc. |
55a2c322 VM |
3 | Contributed by Vladimir Makarov <vmakarov@redhat.com>. |
4 | ||
5 | This file is part of GCC. | |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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/>. */ | |
20 | ||
21 | ||
22 | /* This file contains a pass making some simple RTL code | |
23 | transformations by coalescing pseudos to remove some move insns. | |
24 | ||
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. | |
29 | ||
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. | |
36 | ||
37 | We don't coalesce special reload pseudos. It complicates LRA code | |
38 | a lot without visible generated code improvement. | |
39 | ||
40 | The pseudo live-ranges are used to find conflicting pseudos during | |
41 | coalescing. | |
42 | ||
43 | Most frequently executed moves is tried to be coalesced first. */ | |
44 | ||
45 | #include "config.h" | |
46 | #include "system.h" | |
47 | #include "coretypes.h" | |
c7131fb2 | 48 | #include "backend.h" |
55a2c322 | 49 | #include "rtl.h" |
957060b5 | 50 | #include "predict.h" |
c7131fb2 | 51 | #include "df.h" |
55a2c322 | 52 | #include "insn-config.h" |
957060b5 | 53 | #include "regs.h" |
4d0cdd0c | 54 | #include "memmodel.h" |
957060b5 | 55 | #include "ira.h" |
55a2c322 | 56 | #include "recog.h" |
55a2c322 | 57 | #include "lra-int.h" |
55a2c322 VM |
58 | |
59 | /* Arrays whose elements represent the first and the next pseudo | |
60 | (regno) in the coalesced pseudos group to which given pseudo (its | |
61 | regno is the index) belongs. The next of the last pseudo in the | |
62 | group refers to the first pseudo in the group, in other words the | |
63 | group is represented by a cyclic list. */ | |
64 | static int *first_coalesced_pseudo, *next_coalesced_pseudo; | |
65 | ||
66 | /* The function is used to sort moves according to their execution | |
67 | frequencies. */ | |
68 | static int | |
69 | move_freq_compare_func (const void *v1p, const void *v2p) | |
70 | { | |
cfa434f6 DM |
71 | rtx_insn *mv1 = *(rtx_insn * const *) v1p; |
72 | rtx_insn *mv2 = *(rtx_insn * const *) v2p; | |
55a2c322 | 73 | int pri1, pri2; |
f4eafc30 | 74 | |
fef37404 VM |
75 | pri1 = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv1)); |
76 | pri2 = REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv2)); | |
55a2c322 VM |
77 | if (pri2 - pri1) |
78 | return pri2 - pri1; | |
79 | ||
80 | /* If frequencies are equal, sort by moves, so that the results of | |
81 | qsort leave nothing to chance. */ | |
82 | return (int) INSN_UID (mv1) - (int) INSN_UID (mv2); | |
83 | } | |
84 | ||
85 | /* Pseudos which go away after coalescing. */ | |
86 | static bitmap_head coalesced_pseudos_bitmap; | |
87 | ||
88 | /* Merge two sets of coalesced pseudos given correspondingly by | |
89 | pseudos REGNO1 and REGNO2 (more accurately merging REGNO2 group | |
90 | into REGNO1 group). Set up COALESCED_PSEUDOS_BITMAP. */ | |
91 | static void | |
92 | merge_pseudos (int regno1, int regno2) | |
93 | { | |
94 | int regno, first, first2, last, next; | |
95 | ||
96 | first = first_coalesced_pseudo[regno1]; | |
97 | if ((first2 = first_coalesced_pseudo[regno2]) == first) | |
98 | return; | |
99 | for (last = regno2, regno = next_coalesced_pseudo[regno2];; | |
100 | regno = next_coalesced_pseudo[regno]) | |
101 | { | |
102 | first_coalesced_pseudo[regno] = first; | |
103 | bitmap_set_bit (&coalesced_pseudos_bitmap, regno); | |
104 | if (regno == regno2) | |
105 | break; | |
106 | last = regno; | |
107 | } | |
108 | next = next_coalesced_pseudo[first]; | |
109 | next_coalesced_pseudo[first] = regno2; | |
110 | next_coalesced_pseudo[last] = next; | |
111 | lra_reg_info[first].live_ranges | |
112 | = (lra_merge_live_ranges | |
113 | (lra_reg_info[first].live_ranges, | |
114 | lra_copy_live_range_list (lra_reg_info[first2].live_ranges))); | |
115 | if (GET_MODE_SIZE (lra_reg_info[first].biggest_mode) | |
116 | < GET_MODE_SIZE (lra_reg_info[first2].biggest_mode)) | |
117 | lra_reg_info[first].biggest_mode = lra_reg_info[first2].biggest_mode; | |
118 | } | |
119 | ||
120 | /* Change pseudos in *LOC on their coalescing group | |
121 | representatives. */ | |
122 | static bool | |
123 | substitute (rtx *loc) | |
124 | { | |
125 | int i, regno; | |
126 | const char *fmt; | |
127 | enum rtx_code code; | |
128 | bool res; | |
129 | ||
130 | if (*loc == NULL_RTX) | |
131 | return false; | |
132 | code = GET_CODE (*loc); | |
133 | if (code == REG) | |
134 | { | |
135 | regno = REGNO (*loc); | |
136 | if (regno < FIRST_PSEUDO_REGISTER | |
137 | || first_coalesced_pseudo[regno] == regno) | |
138 | return false; | |
139 | *loc = regno_reg_rtx[first_coalesced_pseudo[regno]]; | |
140 | return true; | |
141 | } | |
142 | ||
143 | res = false; | |
144 | fmt = GET_RTX_FORMAT (code); | |
145 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
146 | { | |
147 | if (fmt[i] == 'e') | |
148 | { | |
149 | if (substitute (&XEXP (*loc, i))) | |
150 | res = true; | |
151 | } | |
152 | else if (fmt[i] == 'E') | |
153 | { | |
154 | int j; | |
155 | ||
156 | for (j = XVECLEN (*loc, i) - 1; j >= 0; j--) | |
157 | if (substitute (&XVECEXP (*loc, i, j))) | |
158 | res = true; | |
159 | } | |
160 | } | |
161 | return res; | |
162 | } | |
163 | ||
cfa434f6 DM |
164 | /* Specialize "substitute" for use on an insn. This can't change |
165 | the insn ptr, just the contents of the insn. */ | |
166 | ||
167 | static bool | |
168 | substitute_within_insn (rtx_insn *insn) | |
169 | { | |
170 | rtx loc = insn; | |
171 | return substitute (&loc); | |
172 | } | |
173 | ||
55a2c322 VM |
174 | /* The current iteration (1, 2, ...) of the coalescing pass. */ |
175 | int lra_coalesce_iter; | |
176 | ||
177 | /* Return true if the move involving REGNO1 and REGNO2 is a potential | |
178 | memory-memory move. */ | |
179 | static bool | |
180 | mem_move_p (int regno1, int regno2) | |
181 | { | |
182 | return reg_renumber[regno1] < 0 && reg_renumber[regno2] < 0; | |
183 | } | |
184 | ||
185 | /* Pseudos used instead of the coalesced pseudos. */ | |
186 | static bitmap_head used_pseudos_bitmap; | |
187 | ||
188 | /* Set up USED_PSEUDOS_BITMAP, and update LR_BITMAP (a BB live info | |
189 | bitmap). */ | |
190 | static void | |
191 | update_live_info (bitmap lr_bitmap) | |
192 | { | |
193 | unsigned int j; | |
194 | bitmap_iterator bi; | |
195 | ||
196 | bitmap_clear (&used_pseudos_bitmap); | |
197 | EXECUTE_IF_AND_IN_BITMAP (&coalesced_pseudos_bitmap, lr_bitmap, | |
198 | FIRST_PSEUDO_REGISTER, j, bi) | |
199 | bitmap_set_bit (&used_pseudos_bitmap, first_coalesced_pseudo[j]); | |
200 | if (! bitmap_empty_p (&used_pseudos_bitmap)) | |
201 | { | |
202 | bitmap_and_compl_into (lr_bitmap, &coalesced_pseudos_bitmap); | |
203 | bitmap_ior_into (lr_bitmap, &used_pseudos_bitmap); | |
204 | } | |
205 | } | |
206 | ||
72ea0d47 | 207 | /* Return true if pseudo REGNO can be potentially coalesced. */ |
55a2c322 | 208 | static bool |
72ea0d47 | 209 | coalescable_pseudo_p (int regno) |
55a2c322 VM |
210 | { |
211 | lra_assert (regno >= FIRST_PSEUDO_REGISTER); | |
72ea0d47 | 212 | return (/* We don't want to coalesce regnos with equivalences, at |
55a2c322 | 213 | least without updating this info. */ |
72ea0d47 | 214 | ira_reg_equiv[regno].constant == NULL_RTX |
55a2c322 VM |
215 | && ira_reg_equiv[regno].memory == NULL_RTX |
216 | && ira_reg_equiv[regno].invariant == NULL_RTX); | |
217 | } | |
218 | ||
219 | /* The major function for aggressive pseudo coalescing of moves only | |
220 | if the both pseudos were spilled and not special reload pseudos. */ | |
221 | bool | |
222 | lra_coalesce (void) | |
223 | { | |
224 | basic_block bb; | |
cfa434f6 DM |
225 | rtx_insn *mv, *insn, *next, **sorted_moves; |
226 | rtx set; | |
72ea0d47 | 227 | int i, mv_num, sregno, dregno; |
55a2c322 VM |
228 | int coalesced_moves; |
229 | int max_regno = max_reg_num (); | |
72ea0d47 | 230 | bitmap_head involved_insns_bitmap; |
35b707ff | 231 | |
55a2c322 VM |
232 | timevar_push (TV_LRA_COALESCE); |
233 | ||
234 | if (lra_dump_file != NULL) | |
235 | fprintf (lra_dump_file, | |
236 | "\n********** Pseudos coalescing #%d: **********\n\n", | |
237 | ++lra_coalesce_iter); | |
238 | first_coalesced_pseudo = XNEWVEC (int, max_regno); | |
239 | next_coalesced_pseudo = XNEWVEC (int, max_regno); | |
240 | for (i = 0; i < max_regno; i++) | |
241 | first_coalesced_pseudo[i] = next_coalesced_pseudo[i] = i; | |
cfa434f6 | 242 | sorted_moves = XNEWVEC (rtx_insn *, get_max_uid ()); |
55a2c322 | 243 | mv_num = 0; |
55a2c322 VM |
244 | /* Collect moves. */ |
245 | coalesced_moves = 0; | |
11cd3bed | 246 | FOR_EACH_BB_FN (bb, cfun) |
55a2c322 VM |
247 | { |
248 | FOR_BB_INSNS_SAFE (bb, insn, next) | |
249 | if (INSN_P (insn) | |
250 | && (set = single_set (insn)) != NULL_RTX | |
251 | && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set)) | |
252 | && (sregno = REGNO (SET_SRC (set))) >= FIRST_PSEUDO_REGISTER | |
253 | && (dregno = REGNO (SET_DEST (set))) >= FIRST_PSEUDO_REGISTER | |
254 | && mem_move_p (sregno, dregno) | |
72ea0d47 | 255 | && coalescable_pseudo_p (sregno) && coalescable_pseudo_p (dregno) |
55a2c322 VM |
256 | && ! side_effects_p (set) |
257 | && !(lra_intersected_live_ranges_p | |
258 | (lra_reg_info[sregno].live_ranges, | |
259 | lra_reg_info[dregno].live_ranges))) | |
260 | sorted_moves[mv_num++] = insn; | |
261 | } | |
55a2c322 VM |
262 | qsort (sorted_moves, mv_num, sizeof (rtx), move_freq_compare_func); |
263 | /* Coalesced copies, most frequently executed first. */ | |
264 | bitmap_initialize (&coalesced_pseudos_bitmap, ®_obstack); | |
265 | bitmap_initialize (&involved_insns_bitmap, ®_obstack); | |
266 | for (i = 0; i < mv_num; i++) | |
267 | { | |
268 | mv = sorted_moves[i]; | |
269 | set = single_set (mv); | |
270 | lra_assert (set != NULL && REG_P (SET_SRC (set)) | |
271 | && REG_P (SET_DEST (set))); | |
272 | sregno = REGNO (SET_SRC (set)); | |
273 | dregno = REGNO (SET_DEST (set)); | |
274 | if (first_coalesced_pseudo[sregno] == first_coalesced_pseudo[dregno]) | |
275 | { | |
276 | coalesced_moves++; | |
277 | if (lra_dump_file != NULL) | |
278 | fprintf | |
279 | (lra_dump_file, " Coalescing move %i:r%d-r%d (freq=%d)\n", | |
280 | INSN_UID (mv), sregno, dregno, | |
fef37404 | 281 | REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv))); |
55a2c322 VM |
282 | /* We updated involved_insns_bitmap when doing the merge. */ |
283 | } | |
284 | else if (!(lra_intersected_live_ranges_p | |
285 | (lra_reg_info[first_coalesced_pseudo[sregno]].live_ranges, | |
286 | lra_reg_info[first_coalesced_pseudo[dregno]].live_ranges))) | |
287 | { | |
288 | coalesced_moves++; | |
289 | if (lra_dump_file != NULL) | |
290 | fprintf | |
291 | (lra_dump_file, | |
292 | " Coalescing move %i:r%d(%d)-r%d(%d) (freq=%d)\n", | |
293 | INSN_UID (mv), sregno, ORIGINAL_REGNO (SET_SRC (set)), | |
294 | dregno, ORIGINAL_REGNO (SET_DEST (set)), | |
fef37404 | 295 | REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv))); |
55a2c322 VM |
296 | bitmap_ior_into (&involved_insns_bitmap, |
297 | &lra_reg_info[sregno].insn_bitmap); | |
298 | bitmap_ior_into (&involved_insns_bitmap, | |
299 | &lra_reg_info[dregno].insn_bitmap); | |
300 | merge_pseudos (sregno, dregno); | |
301 | } | |
302 | } | |
303 | bitmap_initialize (&used_pseudos_bitmap, ®_obstack); | |
11cd3bed | 304 | FOR_EACH_BB_FN (bb, cfun) |
55a2c322 VM |
305 | { |
306 | update_live_info (df_get_live_in (bb)); | |
307 | update_live_info (df_get_live_out (bb)); | |
308 | FOR_BB_INSNS_SAFE (bb, insn, next) | |
309 | if (INSN_P (insn) | |
310 | && bitmap_bit_p (&involved_insns_bitmap, INSN_UID (insn))) | |
311 | { | |
cfa434f6 | 312 | if (! substitute_within_insn (insn)) |
55a2c322 VM |
313 | continue; |
314 | lra_update_insn_regno_info (insn); | |
315 | if ((set = single_set (insn)) != NULL_RTX && set_noop_p (set)) | |
316 | { | |
317 | /* Coalesced move. */ | |
318 | if (lra_dump_file != NULL) | |
319 | fprintf (lra_dump_file, " Removing move %i (freq=%d)\n", | |
fef37404 VM |
320 | INSN_UID (insn), |
321 | REG_FREQ_FROM_BB (BLOCK_FOR_INSN (insn))); | |
55a2c322 VM |
322 | lra_set_insn_deleted (insn); |
323 | } | |
324 | } | |
325 | } | |
c9846a8c VM |
326 | /* If we have situation after inheritance pass: |
327 | ||
35b707ff | 328 | r1 <- p1 insn originally setting p1 |
c9846a8c VM |
329 | i1 <- r1 setting inheritance i1 from reload r1 |
330 | ... | |
331 | ... <- ... p2 ... dead p2 | |
332 | .. | |
333 | p1 <- i1 | |
334 | r2 <- i1 | |
335 | ...<- ... r2 ... | |
336 | ||
337 | And we are coalescing p1 and p2 using p1. In this case i1 and p1 | |
338 | should have different values, otherwise they can get the same | |
339 | hard reg and this is wrong for insn using p2 before coalescing. | |
35b707ff VM |
340 | The situation even can be more complicated when new reload |
341 | pseudos occur after the inheriatnce. So invalidate the result | |
342 | pseudos. */ | |
343 | for (i = 0; i < max_regno; i++) | |
344 | if (first_coalesced_pseudo[i] == i | |
345 | && first_coalesced_pseudo[i] != next_coalesced_pseudo[i]) | |
c9846a8c | 346 | { |
35b707ff | 347 | lra_set_regno_unique_value (i); |
c9846a8c VM |
348 | if (lra_dump_file != NULL) |
349 | fprintf (lra_dump_file, | |
35b707ff | 350 | " Make unique value for coalescing result r%d\n", i); |
c9846a8c | 351 | } |
55a2c322 VM |
352 | bitmap_clear (&used_pseudos_bitmap); |
353 | bitmap_clear (&involved_insns_bitmap); | |
354 | bitmap_clear (&coalesced_pseudos_bitmap); | |
355 | if (lra_dump_file != NULL && coalesced_moves != 0) | |
356 | fprintf (lra_dump_file, "Coalesced Moves = %d\n", coalesced_moves); | |
357 | free (sorted_moves); | |
358 | free (next_coalesced_pseudo); | |
359 | free (first_coalesced_pseudo); | |
360 | timevar_pop (TV_LRA_COALESCE); | |
361 | return coalesced_moves != 0; | |
362 | } |