gcc/tree-ssa-live.h

   1 /* Routines for liveness in SSA trees.
   2    Copyright (C) 2003-2016 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 } *var_map;
  66
  67
  68 /* Value used to represent no partition number.  */
  69 #define NO_PARTITION            -1
  70
  71 extern var_map init_var_map (int);
  72 extern void delete_var_map (var_map);
  73 extern int var_union (var_map, tree, tree);
  74 extern void partition_view_normal (var_map);
  75 extern void partition_view_bitmap (var_map, bitmap);
  76 extern void dump_scope_blocks (FILE *, int);
  77 extern void debug_scope_block (tree, int);
  78 extern void debug_scope_blocks (int);
  79 extern void remove_unused_locals (void);
  80 extern void dump_var_map (FILE *, var_map);
  81 extern void debug (_var_map &ref);
  82 extern void debug (_var_map *ptr);
  83 extern void register_ssa_partition_check (tree ssa_var);
  84
  85
  86 /* Return number of partitions in MAP.  */
  87
  88 static inline unsigned
  89 num_var_partitions (var_map map)
  90 {
  91   return map->num_partitions;
  92 }
  93
  94
  95 /* Given partition index I from MAP, return the variable which represents that
  96    partition.  */
  97
  98 static inline tree
  99 partition_to_var (var_map map, int i)
 100 {
 101   tree name;
 102   if (map->view_to_partition)
 103     i = map->view_to_partition[i];
 104   i = partition_find (map->var_partition, i);
 105   name = ssa_name (i);
 106   return name;
 107 }
 108
 109
 110 /* Given ssa_name VERSION, if it has a partition in MAP,  return the var it
 111    is associated with.  Otherwise return NULL.  */
 112
 113 static inline tree
 114 version_to_var (var_map map, int version)
 115 {
 116   int part;
 117   part = partition_find (map->var_partition, version);
 118   if (map->partition_to_view)
 119     part = map->partition_to_view[part];
 120   if (part == NO_PARTITION)
 121     return NULL_TREE;
 122
 123   return partition_to_var (map, part);
 124 }
 125
 126
 127 /* Given VAR, return the partition number in MAP which contains it.
 128    NO_PARTITION is returned if it's not in any partition.  */
 129
 130 static inline int
 131 var_to_partition (var_map map, tree var)
 132 {
 133   int part;
 134
 135   part = partition_find (map->var_partition, SSA_NAME_VERSION (var));
 136   if (map->partition_to_view)
 137     part = map->partition_to_view[part];
 138   return part;
 139 }
 140
 141
 142 /* Given VAR, return the variable which represents the entire partition
 143    it is a member of in MAP.  NULL is returned if it is not in a partition.  */
 144
 145 static inline tree
 146 var_to_partition_to_var (var_map map, tree var)
 147 {
 148   int part;
 149
 150   part = var_to_partition (map, var);
 151   if (part == NO_PARTITION)
 152     return NULL_TREE;
 153   return partition_to_var (map, part);
 154 }
 155
 156
 157 /* Return the index into the basevar table for PARTITION's base in MAP.  */
 158
 159 static inline int
 160 basevar_index (var_map map, int partition)
 161 {
 162   gcc_checking_assert (partition >= 0
 163                        && partition <= (int) num_var_partitions (map));
 164   return map->partition_to_base_index[partition];
 165 }
 166
 167
 168 /* Return the number of different base variables in MAP.  */
 169
 170 static inline int
 171 num_basevars (var_map map)
 172 {
 173   return map->num_basevars;
 174 }
 175
 176
 177
 178 /* This routine registers a partition for SSA_VAR with MAP.  Any unregistered
 179    partitions may be filtered out by a view later.  */
 180
 181 static inline void
 182 register_ssa_partition (var_map map ATTRIBUTE_UNUSED, tree ssa_var)
 183 {
 184   if (flag_checking)
 185     register_ssa_partition_check (ssa_var);
 186 }
 187
 188
 189 /*  ---------------- live on entry/exit info ------------------------------
 190
 191     This structure is used to represent live range information on SSA based
 192     trees. A partition map must be provided, and based on the active partitions,
 193     live-on-entry information and live-on-exit information can be calculated.
 194     As well, partitions are marked as to whether they are global (live
 195     outside the basic block they are defined in).
 196
 197     The live-on-entry information is per block.  It provide a bitmap for
 198     each block which has a bit set for each partition that is live on entry to
 199     that block.
 200
 201     The live-on-exit information is per block.  It provides a bitmap for each
 202     block indicating which partitions are live on exit from the block.
 203
 204     For the purposes of this implementation, we treat the elements of a PHI
 205     as follows:
 206
 207        Uses in a PHI are considered LIVE-ON-EXIT to the block from which they
 208        originate. They are *NOT* considered live on entry to the block
 209        containing the PHI node.
 210
 211        The Def of a PHI node is *not* considered live on entry to the block.
 212        It is considered to be "define early" in the block. Picture it as each
 213        block having a stmt (or block-preheader) before the first real stmt in
 214        the block which defines all the variables that are defined by PHIs.
 215
 216     -----------------------------------------------------------------------  */
 217
 218
 219 typedef struct tree_live_info_d
 220 {
 221   /* Var map this relates to.  */
 222   var_map map;
 223
 224   /* Bitmap indicating which partitions are global.  */
 225   bitmap global;
 226
 227   /* Bitmaps of live on entry blocks for partition elements.  */
 228   bitmap_head *livein;
 229
 230   /* Bitmaps of what variables are live on exit for a basic blocks.  */
 231   bitmap_head *liveout;
 232
 233   /* Number of basic blocks when live on exit calculated.  */
 234   int num_blocks;
 235
 236   /* Vector used when creating live ranges as a visited stack.  */
 237   int *work_stack;
 238
 239   /* Top of workstack.  */
 240   int *stack_top;
 241
 242   /* Obstacks to allocate the bitmaps on.  */
 243   bitmap_obstack livein_obstack;
 244   bitmap_obstack liveout_obstack;
 245 } *tree_live_info_p;
 246
 247
 248 #define LIVEDUMP_ENTRY  0x01
 249 #define LIVEDUMP_EXIT   0x02
 250 #define LIVEDUMP_ALL    (LIVEDUMP_ENTRY | LIVEDUMP_EXIT)
 251 extern void delete_tree_live_info (tree_live_info_p);
 252 extern tree_live_info_p calculate_live_ranges (var_map, bool);
 253 extern void debug (tree_live_info_d &ref);
 254 extern void debug (tree_live_info_d *ptr);
 255 extern void dump_live_info (FILE *, tree_live_info_p, int);
 256
 257
 258 /*  Return TRUE if P is marked as a global in LIVE.  */
 259
 260 static inline int
 261 partition_is_global (tree_live_info_p live, int p)
 262 {
 263   gcc_checking_assert (live->global);
 264   return bitmap_bit_p (live->global, p);
 265 }
 266
 267
 268 /* Return the bitmap from LIVE representing the live on entry blocks for
 269    partition P.  */
 270
 271 static inline bitmap
 272 live_on_entry (tree_live_info_p live, basic_block bb)
 273 {
 274   gcc_checking_assert (live->livein
 275                        && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
 276                        && bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
 277
 278   return &live->livein[bb->index];
 279 }
 280
 281
 282 /* Return the bitmap from LIVE representing the live on exit partitions from
 283    block BB.  */
 284
 285 static inline bitmap
 286 live_on_exit (tree_live_info_p live, basic_block bb)
 287 {
 288   gcc_checking_assert (live->liveout
 289                        && bb != ENTRY_BLOCK_PTR_FOR_FN (cfun)
 290                        && bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
 291
 292   return &live->liveout[bb->index];
 293 }
 294
 295
 296 /* Return the partition map which the information in LIVE utilizes.  */
 297
 298 static inline var_map
 299 live_var_map (tree_live_info_p live)
 300 {
 301   return live->map;
 302 }
 303
 304
 305 /* Merge the live on entry information in LIVE for partitions P1 and P2. Place
 306    the result into P1.  Clear P2.  */
 307
 308 static inline void
 309 live_merge_and_clear (tree_live_info_p live, int p1, int p2)
 310 {
 311   gcc_checking_assert (&live->livein[p1] && &live->livein[p2]);
 312   bitmap_ior_into (&live->livein[p1], &live->livein[p2]);
 313   bitmap_clear (&live->livein[p2]);
 314 }
 315
 316
 317 /* Mark partition P as live on entry to basic block BB in LIVE.  */
 318
 319 static inline void
 320 make_live_on_entry (tree_live_info_p live, basic_block bb , int p)
 321 {
 322   bitmap_set_bit (&live->livein[bb->index], p);
 323   bitmap_set_bit (live->global, p);
 324 }
 325
 326 #endif /* _TREE_SSA_LIVE_H  */