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"
64 #include "basic-block.h"
71 /* Arrays whose elements represent the first and the next pseudo
72 (regno) in the coalesced pseudos group to which given pseudo (its
73 regno is the index) belongs. The next of the last pseudo in the
74 group refers to the first pseudo in the group, in other words the
75 group is represented by a cyclic list. */
76 static int *first_coalesced_pseudo
, *next_coalesced_pseudo
;
78 /* The function is used to sort moves according to their execution
81 move_freq_compare_func (const void *v1p
, const void *v2p
)
83 rtx_insn
*mv1
= *(rtx_insn
* const *) v1p
;
84 rtx_insn
*mv2
= *(rtx_insn
* const *) v2p
;
87 pri1
= REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv1
));
88 pri2
= REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv2
));
92 /* If frequencies are equal, sort by moves, so that the results of
93 qsort leave nothing to chance. */
94 return (int) INSN_UID (mv1
) - (int) INSN_UID (mv2
);
97 /* Pseudos which go away after coalescing. */
98 static bitmap_head coalesced_pseudos_bitmap
;
100 /* Merge two sets of coalesced pseudos given correspondingly by
101 pseudos REGNO1 and REGNO2 (more accurately merging REGNO2 group
102 into REGNO1 group). Set up COALESCED_PSEUDOS_BITMAP. */
104 merge_pseudos (int regno1
, int regno2
)
106 int regno
, first
, first2
, last
, next
;
108 first
= first_coalesced_pseudo
[regno1
];
109 if ((first2
= first_coalesced_pseudo
[regno2
]) == first
)
111 for (last
= regno2
, regno
= next_coalesced_pseudo
[regno2
];;
112 regno
= next_coalesced_pseudo
[regno
])
114 first_coalesced_pseudo
[regno
] = first
;
115 bitmap_set_bit (&coalesced_pseudos_bitmap
, regno
);
120 next
= next_coalesced_pseudo
[first
];
121 next_coalesced_pseudo
[first
] = regno2
;
122 next_coalesced_pseudo
[last
] = next
;
123 lra_reg_info
[first
].live_ranges
124 = (lra_merge_live_ranges
125 (lra_reg_info
[first
].live_ranges
,
126 lra_copy_live_range_list (lra_reg_info
[first2
].live_ranges
)));
127 if (GET_MODE_SIZE (lra_reg_info
[first
].biggest_mode
)
128 < GET_MODE_SIZE (lra_reg_info
[first2
].biggest_mode
))
129 lra_reg_info
[first
].biggest_mode
= lra_reg_info
[first2
].biggest_mode
;
132 /* Change pseudos in *LOC on their coalescing group
135 substitute (rtx
*loc
)
142 if (*loc
== NULL_RTX
)
144 code
= GET_CODE (*loc
);
147 regno
= REGNO (*loc
);
148 if (regno
< FIRST_PSEUDO_REGISTER
149 || first_coalesced_pseudo
[regno
] == regno
)
151 *loc
= regno_reg_rtx
[first_coalesced_pseudo
[regno
]];
156 fmt
= GET_RTX_FORMAT (code
);
157 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
161 if (substitute (&XEXP (*loc
, i
)))
164 else if (fmt
[i
] == 'E')
168 for (j
= XVECLEN (*loc
, i
) - 1; j
>= 0; j
--)
169 if (substitute (&XVECEXP (*loc
, i
, j
)))
176 /* Specialize "substitute" for use on an insn. This can't change
177 the insn ptr, just the contents of the insn. */
180 substitute_within_insn (rtx_insn
*insn
)
183 return substitute (&loc
);
186 /* The current iteration (1, 2, ...) of the coalescing pass. */
187 int lra_coalesce_iter
;
189 /* Return true if the move involving REGNO1 and REGNO2 is a potential
190 memory-memory move. */
192 mem_move_p (int regno1
, int regno2
)
194 return reg_renumber
[regno1
] < 0 && reg_renumber
[regno2
] < 0;
197 /* Pseudos used instead of the coalesced pseudos. */
198 static bitmap_head used_pseudos_bitmap
;
200 /* Set up USED_PSEUDOS_BITMAP, and update LR_BITMAP (a BB live info
203 update_live_info (bitmap lr_bitmap
)
208 bitmap_clear (&used_pseudos_bitmap
);
209 EXECUTE_IF_AND_IN_BITMAP (&coalesced_pseudos_bitmap
, lr_bitmap
,
210 FIRST_PSEUDO_REGISTER
, j
, bi
)
211 bitmap_set_bit (&used_pseudos_bitmap
, first_coalesced_pseudo
[j
]);
212 if (! bitmap_empty_p (&used_pseudos_bitmap
))
214 bitmap_and_compl_into (lr_bitmap
, &coalesced_pseudos_bitmap
);
215 bitmap_ior_into (lr_bitmap
, &used_pseudos_bitmap
);
219 /* Return true if pseudo REGNO can be potentially coalesced. */
221 coalescable_pseudo_p (int regno
)
223 lra_assert (regno
>= FIRST_PSEUDO_REGISTER
);
224 return (/* We don't want to coalesce regnos with equivalences, at
225 least without updating this info. */
226 ira_reg_equiv
[regno
].constant
== NULL_RTX
227 && ira_reg_equiv
[regno
].memory
== NULL_RTX
228 && ira_reg_equiv
[regno
].invariant
== NULL_RTX
);
231 /* The major function for aggressive pseudo coalescing of moves only
232 if the both pseudos were spilled and not special reload pseudos. */
237 rtx_insn
*mv
, *insn
, *next
, **sorted_moves
;
239 int i
, mv_num
, sregno
, dregno
;
242 int max_regno
= max_reg_num ();
243 bitmap_head involved_insns_bitmap
;
244 bitmap_head result_pseudo_vals_bitmap
;
247 timevar_push (TV_LRA_COALESCE
);
249 if (lra_dump_file
!= NULL
)
250 fprintf (lra_dump_file
,
251 "\n********** Pseudos coalescing #%d: **********\n\n",
252 ++lra_coalesce_iter
);
253 first_coalesced_pseudo
= XNEWVEC (int, max_regno
);
254 next_coalesced_pseudo
= XNEWVEC (int, max_regno
);
255 for (i
= 0; i
< max_regno
; i
++)
256 first_coalesced_pseudo
[i
] = next_coalesced_pseudo
[i
] = i
;
257 sorted_moves
= XNEWVEC (rtx_insn
*, get_max_uid ());
261 FOR_EACH_BB_FN (bb
, cfun
)
263 FOR_BB_INSNS_SAFE (bb
, insn
, next
)
265 && (set
= single_set (insn
)) != NULL_RTX
266 && REG_P (SET_DEST (set
)) && REG_P (SET_SRC (set
))
267 && (sregno
= REGNO (SET_SRC (set
))) >= FIRST_PSEUDO_REGISTER
268 && (dregno
= REGNO (SET_DEST (set
))) >= FIRST_PSEUDO_REGISTER
269 && mem_move_p (sregno
, dregno
)
270 && coalescable_pseudo_p (sregno
) && coalescable_pseudo_p (dregno
)
271 && ! side_effects_p (set
)
272 && !(lra_intersected_live_ranges_p
273 (lra_reg_info
[sregno
].live_ranges
,
274 lra_reg_info
[dregno
].live_ranges
)))
275 sorted_moves
[mv_num
++] = insn
;
277 qsort (sorted_moves
, mv_num
, sizeof (rtx
), move_freq_compare_func
);
278 /* Coalesced copies, most frequently executed first. */
279 bitmap_initialize (&coalesced_pseudos_bitmap
, ®_obstack
);
280 bitmap_initialize (&involved_insns_bitmap
, ®_obstack
);
281 for (i
= 0; i
< mv_num
; i
++)
283 mv
= sorted_moves
[i
];
284 set
= single_set (mv
);
285 lra_assert (set
!= NULL
&& REG_P (SET_SRC (set
))
286 && REG_P (SET_DEST (set
)));
287 sregno
= REGNO (SET_SRC (set
));
288 dregno
= REGNO (SET_DEST (set
));
289 if (first_coalesced_pseudo
[sregno
] == first_coalesced_pseudo
[dregno
])
292 if (lra_dump_file
!= NULL
)
294 (lra_dump_file
, " Coalescing move %i:r%d-r%d (freq=%d)\n",
295 INSN_UID (mv
), sregno
, dregno
,
296 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv
)));
297 /* We updated involved_insns_bitmap when doing the merge. */
299 else if (!(lra_intersected_live_ranges_p
300 (lra_reg_info
[first_coalesced_pseudo
[sregno
]].live_ranges
,
301 lra_reg_info
[first_coalesced_pseudo
[dregno
]].live_ranges
)))
304 if (lra_dump_file
!= NULL
)
307 " Coalescing move %i:r%d(%d)-r%d(%d) (freq=%d)\n",
308 INSN_UID (mv
), sregno
, ORIGINAL_REGNO (SET_SRC (set
)),
309 dregno
, ORIGINAL_REGNO (SET_DEST (set
)),
310 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (mv
)));
311 bitmap_ior_into (&involved_insns_bitmap
,
312 &lra_reg_info
[sregno
].insn_bitmap
);
313 bitmap_ior_into (&involved_insns_bitmap
,
314 &lra_reg_info
[dregno
].insn_bitmap
);
315 merge_pseudos (sregno
, dregno
);
318 bitmap_initialize (&used_pseudos_bitmap
, ®_obstack
);
319 FOR_EACH_BB_FN (bb
, cfun
)
321 update_live_info (df_get_live_in (bb
));
322 update_live_info (df_get_live_out (bb
));
323 FOR_BB_INSNS_SAFE (bb
, insn
, next
)
325 && bitmap_bit_p (&involved_insns_bitmap
, INSN_UID (insn
)))
327 if (! substitute_within_insn (insn
))
329 lra_update_insn_regno_info (insn
);
330 if ((set
= single_set (insn
)) != NULL_RTX
&& set_noop_p (set
))
332 /* Coalesced move. */
333 if (lra_dump_file
!= NULL
)
334 fprintf (lra_dump_file
, " Removing move %i (freq=%d)\n",
336 REG_FREQ_FROM_BB (BLOCK_FOR_INSN (insn
)));
337 lra_set_insn_deleted (insn
);
341 /* If we have situation after inheritance pass:
343 r1 <- ... insn originally setting p1
344 i1 <- r1 setting inheritance i1 from reload r1
346 ... <- ... p2 ... dead p2
352 And we are coalescing p1 and p2 using p1. In this case i1 and p1
353 should have different values, otherwise they can get the same
354 hard reg and this is wrong for insn using p2 before coalescing.
355 So invalidate such inheritance pseudo values. */
356 bitmap_initialize (&result_pseudo_vals_bitmap
, ®_obstack
);
357 EXECUTE_IF_SET_IN_BITMAP (&coalesced_pseudos_bitmap
, 0, regno
, bi
)
358 bitmap_set_bit (&result_pseudo_vals_bitmap
,
359 lra_reg_info
[first_coalesced_pseudo
[regno
]].val
);
360 EXECUTE_IF_SET_IN_BITMAP (&lra_inheritance_pseudos
, 0, regno
, bi
)
361 if (bitmap_bit_p (&result_pseudo_vals_bitmap
, lra_reg_info
[regno
].val
))
363 lra_set_regno_unique_value (regno
);
364 if (lra_dump_file
!= NULL
)
365 fprintf (lra_dump_file
,
366 " Make unique value for inheritance r%d\n", regno
);
368 bitmap_clear (&result_pseudo_vals_bitmap
);
369 bitmap_clear (&used_pseudos_bitmap
);
370 bitmap_clear (&involved_insns_bitmap
);
371 bitmap_clear (&coalesced_pseudos_bitmap
);
372 if (lra_dump_file
!= NULL
&& coalesced_moves
!= 0)
373 fprintf (lra_dump_file
, "Coalesced Moves = %d\n", coalesced_moves
);
375 free (next_coalesced_pseudo
);
376 free (first_coalesced_pseudo
);
377 timevar_pop (TV_LRA_COALESCE
);
378 return coalesced_moves
!= 0;