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
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
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
43 Most frequently executed moves is tried to be coalesced first. */
47 #include "coretypes.h"
51 #include "insn-config.h"
55 #include "hard-reg-set.h"
59 #include "basic-block.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
76 move_freq_compare_func (const void *v1p
, const void *v2p
)
78 rtx_insn
*mv1
= *(rtx_insn
* const *) v1p
;
79 rtx_insn
*mv2
= *(rtx_insn
* const *) v2p
;
82 pri1
= REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv1
));
83 pri2
= REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv2
));
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. */
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
)
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
);
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
130 substitute (rtx
*loc
)
137 if (*loc
== NULL_RTX
)
139 code
= GET_CODE (*loc
);
142 regno
= REGNO (*loc
);
143 if (regno
< FIRST_PSEUDO_REGISTER
144 || first_coalesced_pseudo
[regno
] == regno
)
146 *loc
= regno_reg_rtx
[first_coalesced_pseudo
[regno
]];
151 fmt
= GET_RTX_FORMAT (code
);
152 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
156 if (substitute (&XEXP (*loc
, i
)))
159 else if (fmt
[i
] == 'E')
163 for (j
= XVECLEN (*loc
, i
) - 1; j
>= 0; j
--)
164 if (substitute (&XVECEXP (*loc
, i
, j
)))
171 /* Specialize "substitute" for use on an insn. This can't change
172 the insn ptr, just the contents of the insn. */
175 substitute_within_insn (rtx_insn
*insn
)
178 return substitute (&loc
);
181 /* The current iteration (1, 2, ...) of the coalescing pass. */
182 int lra_coalesce_iter
;
184 /* Return true if the move involving REGNO1 and REGNO2 is a potential
185 memory-memory move. */
187 mem_move_p (int regno1
, int regno2
)
189 return reg_renumber
[regno1
] < 0 && reg_renumber
[regno2
] < 0;
192 /* Pseudos used instead of the coalesced pseudos. */
193 static bitmap_head used_pseudos_bitmap
;
195 /* Set up USED_PSEUDOS_BITMAP, and update LR_BITMAP (a BB live info
198 update_live_info (bitmap lr_bitmap
)
203 bitmap_clear (&used_pseudos_bitmap
);
204 EXECUTE_IF_AND_IN_BITMAP (&coalesced_pseudos_bitmap
, lr_bitmap
,
205 FIRST_PSEUDO_REGISTER
, j
, bi
)
206 bitmap_set_bit (&used_pseudos_bitmap
, first_coalesced_pseudo
[j
]);
207 if (! bitmap_empty_p (&used_pseudos_bitmap
))
209 bitmap_and_compl_into (lr_bitmap
, &coalesced_pseudos_bitmap
);
210 bitmap_ior_into (lr_bitmap
, &used_pseudos_bitmap
);
214 /* Return true if pseudo REGNO can be potentially coalesced. */
216 coalescable_pseudo_p (int regno
)
218 lra_assert (regno
>= FIRST_PSEUDO_REGISTER
);
219 return (/* We don't want to coalesce regnos with equivalences, at
220 least without updating this info. */
221 ira_reg_equiv
[regno
].constant
== NULL_RTX
222 && ira_reg_equiv
[regno
].memory
== NULL_RTX
223 && ira_reg_equiv
[regno
].invariant
== NULL_RTX
);
226 /* The major function for aggressive pseudo coalescing of moves only
227 if the both pseudos were spilled and not special reload pseudos. */
232 rtx_insn
*mv
, *insn
, *next
, **sorted_moves
;
234 int i
, mv_num
, sregno
, dregno
;
237 int max_regno
= max_reg_num ();
238 bitmap_head involved_insns_bitmap
;
239 bitmap_head result_pseudo_vals_bitmap
;
242 timevar_push (TV_LRA_COALESCE
);
244 if (lra_dump_file
!= NULL
)
245 fprintf (lra_dump_file
,
246 "\n********** Pseudos coalescing #%d: **********\n\n",
247 ++lra_coalesce_iter
);
248 first_coalesced_pseudo
= XNEWVEC (int, max_regno
);
249 next_coalesced_pseudo
= XNEWVEC (int, max_regno
);
250 for (i
= 0; i
< max_regno
; i
++)
251 first_coalesced_pseudo
[i
] = next_coalesced_pseudo
[i
] = i
;
252 sorted_moves
= XNEWVEC (rtx_insn
*, get_max_uid ());
256 FOR_EACH_BB_FN (bb
, cfun
)
258 FOR_BB_INSNS_SAFE (bb
, insn
, next
)
260 && (set
= single_set (insn
)) != NULL_RTX
261 && REG_P (SET_DEST (set
)) && REG_P (SET_SRC (set
))
262 && (sregno
= REGNO (SET_SRC (set
))) >= FIRST_PSEUDO_REGISTER
263 && (dregno
= REGNO (SET_DEST (set
))) >= FIRST_PSEUDO_REGISTER
264 && mem_move_p (sregno
, dregno
)
265 && coalescable_pseudo_p (sregno
) && coalescable_pseudo_p (dregno
)
266 && ! side_effects_p (set
)
267 && !(lra_intersected_live_ranges_p
268 (lra_reg_info
[sregno
].live_ranges
,
269 lra_reg_info
[dregno
].live_ranges
)))
270 sorted_moves
[mv_num
++] = insn
;
272 qsort (sorted_moves
, mv_num
, sizeof (rtx
), move_freq_compare_func
);
273 /* Coalesced copies, most frequently executed first. */
274 bitmap_initialize (&coalesced_pseudos_bitmap
, ®_obstack
);
275 bitmap_initialize (&involved_insns_bitmap
, ®_obstack
);
276 for (i
= 0; i
< mv_num
; i
++)
278 mv
= sorted_moves
[i
];
279 set
= single_set (mv
);
280 lra_assert (set
!= NULL
&& REG_P (SET_SRC (set
))
281 && REG_P (SET_DEST (set
)));
282 sregno
= REGNO (SET_SRC (set
));
283 dregno
= REGNO (SET_DEST (set
));
284 if (first_coalesced_pseudo
[sregno
] == first_coalesced_pseudo
[dregno
])
287 if (lra_dump_file
!= NULL
)
289 (lra_dump_file
, " Coalescing move %i:r%d-r%d (freq=%d)\n",
290 INSN_UID (mv
), sregno
, dregno
,
291 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv
)));
292 /* We updated involved_insns_bitmap when doing the merge. */
294 else if (!(lra_intersected_live_ranges_p
295 (lra_reg_info
[first_coalesced_pseudo
[sregno
]].live_ranges
,
296 lra_reg_info
[first_coalesced_pseudo
[dregno
]].live_ranges
)))
299 if (lra_dump_file
!= NULL
)
302 " Coalescing move %i:r%d(%d)-r%d(%d) (freq=%d)\n",
303 INSN_UID (mv
), sregno
, ORIGINAL_REGNO (SET_SRC (set
)),
304 dregno
, ORIGINAL_REGNO (SET_DEST (set
)),
305 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv
)));
306 bitmap_ior_into (&involved_insns_bitmap
,
307 &lra_reg_info
[sregno
].insn_bitmap
);
308 bitmap_ior_into (&involved_insns_bitmap
,
309 &lra_reg_info
[dregno
].insn_bitmap
);
310 merge_pseudos (sregno
, dregno
);
313 bitmap_initialize (&used_pseudos_bitmap
, ®_obstack
);
314 FOR_EACH_BB_FN (bb
, cfun
)
316 update_live_info (df_get_live_in (bb
));
317 update_live_info (df_get_live_out (bb
));
318 FOR_BB_INSNS_SAFE (bb
, insn
, next
)
320 && bitmap_bit_p (&involved_insns_bitmap
, INSN_UID (insn
)))
322 if (! substitute_within_insn (insn
))
324 lra_update_insn_regno_info (insn
);
325 if ((set
= single_set (insn
)) != NULL_RTX
&& set_noop_p (set
))
327 /* Coalesced move. */
328 if (lra_dump_file
!= NULL
)
329 fprintf (lra_dump_file
, " Removing move %i (freq=%d)\n",
331 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (insn
)));
332 lra_set_insn_deleted (insn
);
336 /* If we have situation after inheritance pass:
338 r1 <- ... insn originally setting p1
339 i1 <- r1 setting inheritance i1 from reload r1
341 ... <- ... p2 ... dead p2
347 And we are coalescing p1 and p2 using p1. In this case i1 and p1
348 should have different values, otherwise they can get the same
349 hard reg and this is wrong for insn using p2 before coalescing.
350 So invalidate such inheritance pseudo values. */
351 bitmap_initialize (&result_pseudo_vals_bitmap
, ®_obstack
);
352 EXECUTE_IF_SET_IN_BITMAP (&coalesced_pseudos_bitmap
, 0, regno
, bi
)
353 bitmap_set_bit (&result_pseudo_vals_bitmap
,
354 lra_reg_info
[first_coalesced_pseudo
[regno
]].val
);
355 EXECUTE_IF_SET_IN_BITMAP (&lra_inheritance_pseudos
, 0, regno
, bi
)
356 if (bitmap_bit_p (&result_pseudo_vals_bitmap
, lra_reg_info
[regno
].val
))
358 lra_set_regno_unique_value (regno
);
359 if (lra_dump_file
!= NULL
)
360 fprintf (lra_dump_file
,
361 " Make unique value for inheritance r%d\n", regno
);
363 bitmap_clear (&result_pseudo_vals_bitmap
);
364 bitmap_clear (&used_pseudos_bitmap
);
365 bitmap_clear (&involved_insns_bitmap
);
366 bitmap_clear (&coalesced_pseudos_bitmap
);
367 if (lra_dump_file
!= NULL
&& coalesced_moves
!= 0)
368 fprintf (lra_dump_file
, "Coalesced Moves = %d\n", coalesced_moves
);
370 free (next_coalesced_pseudo
);
371 free (first_coalesced_pseudo
);
372 timevar_pop (TV_LRA_COALESCE
);
373 return coalesced_moves
!= 0;