1 /* Routines for liveness in SSA trees.
2 Copyright (C) 2003-2023 Free Software Foundation, Inc.
3 Contributed by Andrew MacLeod <amacleod@redhat.com>
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License 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 #ifndef _TREE_SSA_LIVE_H
23 #define _TREE_SSA_LIVE_H 1
24
25 #include "partition.h"
26
27 /* Used to create the variable mapping when we go out of SSA form.
28
29 Mapping from an ssa_name to a partition number is maintained, as well as
30 partition number back to ssa_name.
31
32 This data structure also supports "views", which work on a subset of all
33 partitions. This allows the coalescer to decide what partitions are
34 interesting to it, and only work with those partitions. Whenever the view
35 is changed, the partition numbers change, but none of the partition groupings
36 change. (ie, it is truly a view since it doesn't change anything)
37
38 The final component of the data structure is the basevar map. This provides
39 a list of all the different base variables which occur in a partition view,
40 and a unique index for each one. Routines are provided to quickly produce
41 the base variable of a partition.
42
43 Note that members of a partition MUST all have the same base variable. */
44
45 typedef struct _var_map
46 {
47 /* The partition manager of all variables. */
48 partition var_partition;
49
50 /* Vector for managing partitions views. */
51 int *partition_to_view;
52 int *view_to_partition;
53
54 /* Current number of partitions in var_map based on the current view. */
55 unsigned int num_partitions;
56
57 /* Original full partition size. */
58 unsigned int partition_size;
59
60 /* Number of base variables in the base var list. */
61 int num_basevars;
62
63 /* Map of partitions numbers to base variable table indexes. */
64 int *partition_to_base_index;
65
66 /* Bitmap of basic block. It describes the region within which the analysis
67 is done. Using pointer avoids allocating memory in out-of-ssa case. */
68 bitmap bmp_bbs;
69
70 /* Vector of basic block in the region. */
71 vec<basic_block> vec_bbs;
72
73 /* True if this map is for out-of-ssa, otherwise for live range
74 computation. When for out-of-ssa, it also means the var map is computed
75 for whole current function. */
76 bool outofssa_p;
77 } *var_map;
78
79
80 /* Value used to represent no partition number. */
81 #define NO_PARTITION -1
82
83 extern var_map init_var_map (int, class loop* = NULL);
84 extern void delete_var_map (var_map);
85 extern int var_union (var_map, tree, tree);
86 extern void partition_view_normal (var_map);
87 extern void partition_view_bitmap (var_map, bitmap);
88 extern void dump_scope_blocks (FILE *, dump_flags_t);
89 extern void debug_scope_block (tree, dump_flags_t);
90 extern void debug_scope_blocks (dump_flags_t);
91 extern void remove_unused_locals (void);
92 extern void dump_var_map (FILE *, var_map);
93 extern void debug (_var_map &ref);
94 extern void debug (_var_map *ptr);
95
96
97 /* Return TRUE if region of the MAP contains basic block BB. */
98
99 inline bool
100 region_contains_p (var_map map, basic_block bb)
101 {
102 /* It's possible that the function is called with ENTRY_BLOCK/EXIT_BLOCK. */
103 if (map->outofssa_p)
104 return (bb->index != ENTRY_BLOCK && bb->index != EXIT_BLOCK);
105
106 return bitmap_bit_p (map->bmp_bbs, bb->index);
107 }
108
109
110 /* Return number of partitions in MAP. */
111
112 inline unsigned
113 num_var_partitions (var_map map)
114 {
115 return map->num_partitions;
116 }
117
118
119 /* Given partition index I from MAP, return the variable which represents that
120 partition. */
121
122 inline tree
123 partition_to_var (var_map map, int i)
124 {
125 tree name;
126 if (map->view_to_partition)
127 i = map->view_to_partition[i];
128 i = partition_find (map->var_partition, i);
129 name = ssa_name (i);
130 return name;
131 }
132
133
134 /* Given ssa_name VERSION, if it has a partition in MAP, return the var it
135 is associated with. Otherwise return NULL. */
136
137 inline tree
138 version_to_var (var_map map, int version)
139 {
140 int part;
141 part = partition_find (map->var_partition, version);
142 if (map->partition_to_view)
143 part = map->partition_to_view[part];
144 if (part == NO_PARTITION)
145 return NULL_TREE;
146
147 return partition_to_var (map, part);
148 }
149
150
151 /* Given VAR, return the partition number in MAP which contains it.
152 NO_PARTITION is returned if it's not in any partition. */
153
154 inline int
155 var_to_partition (var_map map, tree var)
156 {
157 int part;
158
159 part = partition_find (map->var_partition, SSA_NAME_VERSION (var));
160 if (map->partition_to_view)
161 part = map->partition_to_view[part];
162 return part;
163 }
164
165
166 /* Given VAR, return the variable which represents the entire partition
167 it is a member of in MAP. NULL is returned if it is not in a partition. */
168
169 inline tree
170 var_to_partition_to_var (var_map map, tree var)
171 {
172 int part;
173
174 part = var_to_partition (map, var);
175 if (part == NO_PARTITION)
176 return NULL_TREE;
177 return partition_to_var (map, part);
178 }
179
180
181 /* Return the index into the basevar table for PARTITION's base in MAP. */
182
183 inline int
184 basevar_index (var_map map, int partition)
185 {
186 gcc_checking_assert (partition >= 0
187 && partition <= (int) num_var_partitions (map));
188 return map->partition_to_base_index[partition];
189 }
190
191
192 /* Return the number of different base variables in MAP. */
193
194 inline int
195 num_basevars (var_map map)
196 {
197 return map->num_basevars;
198 }
199
200
201 /* ---------------- live on entry/exit info ------------------------------
202
203 This structure is used to represent live range information on SSA based
204 trees. A partition map must be provided, and based on the active partitions,
205 live-on-entry information and live-on-exit information can be calculated.
206 As well, partitions are marked as to whether they are global (live
207 outside the basic block they are defined in).
208
209 The live-on-entry information is per block. It provide a bitmap for
210 each block which has a bit set for each partition that is live on entry to
211 that block.
212
213 The live-on-exit information is per block. It provides a bitmap for each
214 block indicating which partitions are live on exit from the block.
215
216 For the purposes of this implementation, we treat the elements of a PHI
217 as follows:
218
219 Uses in a PHI are considered LIVE-ON-EXIT to the block from which they
220 originate. They are *NOT* considered live on entry to the block
221 containing the PHI node.
222
223 The Def of a PHI node is *not* considered live on entry to the block.
224 It is considered to be "define early" in the block. Picture it as each
225 block having a stmt (or block-preheader) before the first real stmt in
226 the block which defines all the variables that are defined by PHIs.
227
228 ----------------------------------------------------------------------- */
229
230
231 typedef struct tree_live_info_d
232 {
233 /* Var map this relates to. */
234 var_map map;
235
236 /* Bitmap indicating which partitions are global. */
237 bitmap global;
238
239 /* Bitmaps of live on entry blocks for partition elements. */
240 bitmap_head *livein;
241
242 /* Bitmaps of what variables are live on exit for a basic blocks. */
243 bitmap_head *liveout;
244
245 /* Number of basic blocks when live on exit calculated. */
246 int num_blocks;
247
248 /* Vector used when creating live ranges as a visited stack. */
249 int *work_stack;
250
251 /* Top of workstack. */
252 int *stack_top;
253
254 /* Obstacks to allocate the bitmaps on. */
255 bitmap_obstack livein_obstack;
256 bitmap_obstack liveout_obstack;
257 } *tree_live_info_p;
258
259
260 #define LIVEDUMP_ENTRY 0x01
261 #define LIVEDUMP_EXIT 0x02
262 #define LIVEDUMP_ALL (LIVEDUMP_ENTRY | LIVEDUMP_EXIT)
263 extern void delete_tree_live_info (tree_live_info_p);
264 extern tree_live_info_p calculate_live_ranges (var_map, bool);
265 extern void debug (tree_live_info_d &ref);
266 extern void debug (tree_live_info_d *ptr);
267 extern void dump_live_info (FILE *, tree_live_info_p, int);
268
269 typedef hash_map<int_hash <unsigned int, -1U>, unsigned int> live_vars_map;
270 extern vec<bitmap_head> compute_live_vars (struct function *, live_vars_map *);
271 extern bitmap live_vars_at_stmt (vec<bitmap_head> &, live_vars_map *,
272 gimple *);
273 extern void destroy_live_vars (vec<bitmap_head> &);
274
275 /* Return TRUE if P is marked as a global in LIVE. */
276
277 inline int
278 partition_is_global (tree_live_info_p live, int p)
279 {
280 gcc_checking_assert (live->global);
281 return bitmap_bit_p (live->global, p);
282 }
283
284
285 /* Return the bitmap from LIVE representing the live on entry blocks for
286 partition P. */
287
288 inline bitmap
289 live_on_entry (tree_live_info_p live, basic_block bb)
290 {
291 gcc_checking_assert (live->livein
292 && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
293 && bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
294
295 return &live->livein[bb->index];
296 }
297
298
299 /* Return the bitmap from LIVE representing the live on exit partitions from
300 block BB. */
301
302 inline bitmap
303 live_on_exit (tree_live_info_p live, basic_block bb)
304 {
305 gcc_checking_assert (live->liveout
306 && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
307 && bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
308
309 return &live->liveout[bb->index];
310 }
311
312
313 /* Return the partition map which the information in LIVE utilizes. */
314
315 inline var_map
316 live_var_map (tree_live_info_p live)
317 {
318 return live->map;
319 }
320
321
322 /* Mark partition P as live on entry to basic block BB in LIVE. */
323
324 inline void
325 make_live_on_entry (tree_live_info_p live, basic_block bb , int p)
326 {
327 bitmap_set_bit (&live->livein[bb->index], p);
328 bitmap_set_bit (live->global, p);
329 }
330
331 #endif /* _TREE_SSA_LIVE_H */