gcc/tree-ssa-live.h

   1 /* Routines for liveness in SSA trees.
   2    Copyright (C) 2003, 2004, 2005, 2007, 2008, 2010
   3    Free Software Foundation, Inc.
   4    Contributed by Andrew MacLeod  <amacleod@redhat.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22
  23 #ifndef _TREE_SSA_LIVE_H
  24 #define _TREE_SSA_LIVE_H 1
  25
  26 #include "partition.h"
  27 #include "vecprim.h"
  28
  29
  30
  31 /* Used to create the variable mapping when we go out of SSA form.
  32
  33    Mapping from an ssa_name to a partition number is maintained, as well as
  34    partition number back to ssa_name.
  35
  36    This data structure also supports "views", which work on a subset of all
  37    partitions.  This allows the coalescer to decide what partitions are
  38    interesting to it, and only work with those partitions.  Whenever the view
  39    is changed, the partition numbers change, but none of the partition groupings
  40    change. (ie, it is truly a view since it doesn't change anything)
  41
  42    The final component of the data structure is the basevar map.  This provides
  43    a list of all the different base variables which occur in a partition view,
  44    and a unique index for each one. Routines are provided to quickly produce
  45    the base variable of a partition.
  46
  47    Note that members of a partition MUST all have the same base variable.  */
  48
  49 typedef struct _var_map
  50 {
  51   /* The partition manager of all variables.  */
  52   partition var_partition;
  53
  54   /* Vector for managing partitions views.  */
  55   int *partition_to_view;
  56   int *view_to_partition;
  57
  58   /* Current number of partitions in var_map based on the current view.  */
  59   unsigned int num_partitions;
  60
  61   /* Original full partition size.  */
  62   unsigned int partition_size;
  63
  64   /* Number of base variables in the base var list.  */
  65   int num_basevars;
  66
  67   /* Map of partitions numbers to base variable table indexes.  */
  68   int *partition_to_base_index;
  69 } *var_map;
  70
  71
  72 /* Value used to represent no partition number.  */
  73 #define NO_PARTITION            -1
  74
  75 extern var_map init_var_map (int);
  76 extern void delete_var_map (var_map);
  77 extern void dump_var_map (FILE *, var_map);
  78 extern int var_union (var_map, tree, tree);
  79 extern void partition_view_normal (var_map, bool);
  80 extern void partition_view_bitmap (var_map, bitmap, bool);
  81 #ifdef ENABLE_CHECKING
  82 extern void register_ssa_partition_check (tree ssa_var);
  83 #endif
  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,
 183                         tree ssa_var ATTRIBUTE_UNUSED)
 184 {
 185 #if defined ENABLE_CHECKING
 186   register_ssa_partition_check (ssa_var);
 187 #endif
 188 }
 189
 190
 191 /*  ---------------- live on entry/exit info ------------------------------
 192
 193     This structure is used to represent live range information on SSA based
 194     trees. A partition map must be provided, and based on the active partitions,
 195     live-on-entry information and live-on-exit information can be calculated.
 196     As well, partitions are marked as to whether they are global (live
 197     outside the basic block they are defined in).
 198
 199     The live-on-entry information is per block.  It provide a bitmap for
 200     each block which has a bit set for each partition that is live on entry to
 201     that block.
 202
 203     The live-on-exit information is per block.  It provides a bitmap for each
 204     block indicating which partitions are live on exit from the block.
 205
 206     For the purposes of this implementation, we treat the elements of a PHI
 207     as follows:
 208
 209        Uses in a PHI are considered LIVE-ON-EXIT to the block from which they
 210        originate. They are *NOT* considered live on entry to the block
 211        containing the PHI node.
 212
 213        The Def of a PHI node is *not* considered live on entry to the block.
 214        It is considered to be "define early" in the block. Picture it as each
 215        block having a stmt (or block-preheader) before the first real stmt in
 216        the block which defines all the variables that are defined by PHIs.
 217
 218     -----------------------------------------------------------------------  */
 219
 220
 221 typedef struct tree_live_info_d
 222 {
 223   /* Var map this relates to.  */
 224   var_map map;
 225
 226   /* Bitmap indicating which partitions are global.  */
 227   bitmap global;
 228
 229   /* Bitmaps of live on entry blocks for partition elements.  */
 230   bitmap_head *livein;
 231
 232   /* Bitmaps of what variables are live on exit for a basic blocks.  */
 233   bitmap_head *liveout;
 234
 235   /* Number of basic blocks when live on exit calculated.  */
 236   int num_blocks;
 237
 238   /* Vector used when creating live ranges as a visited stack.  */
 239   int *work_stack;
 240
 241   /* Top of workstack.  */
 242   int *stack_top;
 243 } *tree_live_info_p;
 244
 245
 246 extern tree_live_info_p calculate_live_ranges (var_map);
 247 extern void calculate_live_on_exit (tree_live_info_p);
 248 extern void delete_tree_live_info (tree_live_info_p);
 249
 250 #define LIVEDUMP_ENTRY  0x01
 251 #define LIVEDUMP_EXIT   0x02
 252 #define LIVEDUMP_ALL    (LIVEDUMP_ENTRY | LIVEDUMP_EXIT)
 253 extern void dump_live_info (FILE *, tree_live_info_p, int);
 254
 255
 256 /*  Return TRUE if P is marked as a global in LIVE.  */
 257
 258 static inline int
 259 partition_is_global (tree_live_info_p live, int p)
 260 {
 261   gcc_checking_assert (live->global);
 262   return bitmap_bit_p (live->global, p);
 263 }
 264
 265
 266 /* Return the bitmap from LIVE representing the live on entry blocks for
 267    partition P.  */
 268
 269 static inline bitmap
 270 live_on_entry (tree_live_info_p live, basic_block bb)
 271 {
 272   gcc_checking_assert (live->livein
 273                        && bb != ENTRY_BLOCK_PTR
 274                        && bb != EXIT_BLOCK_PTR);
 275
 276   return &live->livein[bb->index];
 277 }
 278
 279
 280 /* Return the bitmap from LIVE representing the live on exit partitions from
 281    block BB.  */
 282
 283 static inline bitmap
 284 live_on_exit (tree_live_info_p live, basic_block bb)
 285 {
 286   gcc_checking_assert (live->liveout
 287                        && bb != ENTRY_BLOCK_PTR
 288                        && bb != EXIT_BLOCK_PTR);
 289
 290   return &live->liveout[bb->index];
 291 }
 292
 293
 294 /* Return the partition map which the information in LIVE utilizes.  */
 295
 296 static inline var_map
 297 live_var_map (tree_live_info_p live)
 298 {
 299   return live->map;
 300 }
 301
 302
 303 /* Merge the live on entry information in LIVE for partitions P1 and P2. Place
 304    the result into P1.  Clear P2.  */
 305
 306 static inline void
 307 live_merge_and_clear (tree_live_info_p live, int p1, int p2)
 308 {
 309   gcc_checking_assert (&live->livein[p1] && &live->livein[p2]);
 310   bitmap_ior_into (&live->livein[p1], &live->livein[p2]);
 311   bitmap_zero (&live->livein[p2]);
 312 }
 313
 314
 315 /* Mark partition P as live on entry to basic block BB in LIVE.  */
 316
 317 static inline void
 318 make_live_on_entry (tree_live_info_p live, basic_block bb , int p)
 319 {
 320   bitmap_set_bit (&live->livein[bb->index], p);
 321   bitmap_set_bit (live->global, p);
 322 }
 323
 324
 325 /* From tree-ssa-coalesce.c  */
 326 extern var_map coalesce_ssa_name (void);
 327
 328
 329 /* From tree-ssa-ter.c  */
 330 extern bitmap find_replaceable_exprs (var_map);
 331 extern void dump_replaceable_exprs (FILE *, bitmap);
 332
 333
 334 #endif /* _TREE_SSA_LIVE_H  */