gcc/tree-ssa-sccvn.h

   1 /* Tree SCC value numbering
   2    Copyright (C) 2007-2024 Free Software Foundation, Inc.
   3    Contributed by Daniel Berlin <dberlin@dberlin.org>
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) 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 #ifndef TREE_SSA_SCCVN_H
  22 #define TREE_SSA_SCCVN_H
  23
  24 /* In tree-ssa-sccvn.cc  */
  25 bool expressions_equal_p (tree, tree, bool = true);
  26
  27
  28 /* TOP of the VN lattice.  */
  29 extern tree VN_TOP;
  30
  31 /* A predicated value.  */
  32 struct vn_pval
  33 {
  34   vn_pval *next;
  35   /* The value of the expression this is attached to is RESULT in
  36      case the expression is computed dominated by one of the blocks
  37      in valid_dominated_by_p.  */
  38   tree result;
  39   unsigned n;
  40   int valid_dominated_by_p[1];
  41 };
  42
  43 /* N-ary operations in the hashtable consist of length operands, an
  44    opcode, and a type.  Result is the value number of the operation,
  45    and hashcode is stored to avoid having to calculate it
  46    repeatedly.  */
  47
  48 typedef struct vn_nary_op_s
  49 {
  50   vn_nary_op_s *next;
  51   vn_nary_op_s *unwind_to;
  52   /* Unique identify that all expressions with the same value have. */
  53   unsigned int value_id;
  54   ENUM_BITFIELD(tree_code) opcode : 16;
  55   unsigned length : 16;
  56   hashval_t hashcode;
  57   unsigned predicated_values : 1;
  58   union {
  59       /* If ! predicated_values this is the value of the expression.  */
  60       tree result;
  61       /* If predicated_values this is a list of values of the expression.  */
  62       vn_pval *values;
  63   } u;
  64   tree type;
  65   tree op[1];
  66 } *vn_nary_op_t;
  67 typedef const struct vn_nary_op_s *const_vn_nary_op_t;
  68
  69 /* Return the size of a vn_nary_op_t with LENGTH operands.  */
  70
  71 inline size_t
  72 sizeof_vn_nary_op (unsigned int length)
  73 {
  74   return sizeof (struct vn_nary_op_s) + sizeof (tree) * length - sizeof (tree);
  75 }
  76
  77 /* Phi nodes in the hashtable consist of their non-VN_TOP phi
  78    arguments, and the basic block the phi is in. Result is the value
  79    number of the operation, and hashcode is stored to avoid having to
  80    calculate it repeatedly.  Phi nodes not in the same block are never
  81    considered equivalent.  */
  82
  83 typedef struct vn_phi_s
  84 {
  85   vn_phi_s *next;
  86   /* Unique identifier that all expressions with the same value have. */
  87   unsigned int value_id;
  88   hashval_t hashcode;
  89   basic_block block;
  90   /* Controlling condition lhs/rhs.  */
  91   tree cclhs;
  92   tree ccrhs;
  93   tree type;
  94   tree result;
  95   /* The number of args is determined by EDGE_COUT (block->preds).  */
  96   tree phiargs[1];
  97 } *vn_phi_t;
  98 typedef const struct vn_phi_s *const_vn_phi_t;
  99
 100 /* Reference operands only exist in reference operations structures.
 101    They consist of an opcode, type, and some number of operands.  For
 102    a given opcode, some, all, or none of the operands may be used.
 103    The operands are there to store the information that makes up the
 104    portion of the addressing calculation that opcode performs.  */
 105
 106 typedef struct vn_reference_op_struct
 107 {
 108   ENUM_BITFIELD(tree_code) opcode : 16;
 109   /* Dependence info, used for [TARGET_]MEM_REF only.  For internal
 110      function calls clique is also used for the internal function code.  */
 111   unsigned short clique;
 112   unsigned short base;
 113   unsigned reverse : 1;
 114   /* For storing TYPE_ALIGN for array ref element size computation.  */
 115   unsigned align : 6;
 116   /* Constant offset this op adds or -1 if it is variable.  */
 117   poly_int64 off;
 118   tree type;
 119   tree op0;
 120   tree op1;
 121   tree op2;
 122 } vn_reference_op_s;
 123 typedef vn_reference_op_s *vn_reference_op_t;
 124 typedef const vn_reference_op_s *const_vn_reference_op_t;
 125
 126 inline unsigned
 127 vn_ref_op_align_unit (vn_reference_op_t op)
 128 {
 129   return op->align ? ((unsigned)1 << (op->align - 1)) / BITS_PER_UNIT : 0;
 130 }
 131
 132 /* A reference operation in the hashtable is representation as
 133    the vuse, representing the memory state at the time of
 134    the operation, and a collection of operands that make up the
 135    addressing calculation.  If two vn_reference_t's have the same set
 136    of operands, they access the same memory location. We also store
 137    the resulting value number, and the hashcode.  */
 138
 139 typedef struct vn_reference_s
 140 {
 141   vn_reference_s *next;
 142   /* Unique identifier that all expressions with the same value have. */
 143   unsigned int value_id;
 144   hashval_t hashcode;
 145   tree vuse;
 146   alias_set_type set;
 147   alias_set_type base_set;
 148   poly_int64 offset;
 149   poly_int64 max_size;
 150   tree type;
 151   unsigned punned : 1;
 152   vec<vn_reference_op_s> operands;
 153   tree result;
 154   tree result_vdef;
 155 } *vn_reference_t;
 156 typedef const struct vn_reference_s *const_vn_reference_t;
 157
 158 typedef struct vn_constant_s
 159 {
 160   unsigned int value_id;
 161   hashval_t hashcode;
 162   tree constant;
 163 } *vn_constant_t;
 164
 165 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
 166 enum vn_kind vn_get_stmt_kind (gimple *);
 167
 168 /* Hash the type TYPE using bits that distinguishes it in the
 169    types_compatible_p sense.  */
 170
 171 inline hashval_t
 172 vn_hash_type (tree type)
 173 {
 174   return (INTEGRAL_TYPE_P (type)
 175           + (INTEGRAL_TYPE_P (type)
 176              ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
 177 }
 178
 179 /* Hash the constant CONSTANT with distinguishing type incompatible
 180    constants in the types_compatible_p sense.  */
 181
 182 inline hashval_t
 183 vn_hash_constant_with_type (tree constant)
 184 {
 185   inchash::hash hstate;
 186   inchash::add_expr (constant, hstate);
 187   hstate.merge_hash (vn_hash_type (TREE_TYPE (constant)));
 188   return hstate.end ();
 189 }
 190
 191 /* Compare the constants C1 and C2 with distinguishing type incompatible
 192    constants in the types_compatible_p sense.  */
 193
 194 inline bool
 195 vn_constant_eq_with_type (tree c1, tree c2)
 196 {
 197   return (expressions_equal_p (c1, c2)
 198           && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
 199 }
 200
 201 /* Instead of having a local availability lattice for each basic-block
 202    and availability at X defined as union of the local availabilities
 203    at X and its dominators we're turning this upside down and track
 204    availability per value given values are usually made available at very
 205    few points.
 206    So we have a chain of LOCATION, LEADER entries where LOCATION is
 207    specifying the basic-block LEADER is made available for VALUE.
 208    We prepend to this chain in RPO order thus for iteration we can simply
 209    remove the last entries.
 210    LOCATION is the basic-block index and LEADER is its SSA name version.  */
 211 struct vn_avail
 212 {
 213   vn_avail *next;
 214   /* The basic-block LEADER is made available.  */
 215   int location;
 216   /* The LEADER for the value we are chained on.  */
 217   int leader;
 218   /* The previous value we pushed a avail record to.  */
 219   struct vn_ssa_aux *next_undo;
 220 };
 221
 222 typedef struct vn_ssa_aux
 223 {
 224   /* SSA name this vn_ssa_aux is associated with in the lattice.  */
 225   tree name;
 226   /* Value number. This may be an SSA name or a constant.  */
 227   tree valnum;
 228   /* Statements to insert if needs_insertion is true.  */
 229   gimple_seq expr;
 230
 231   /* AVAIL entries, last in RPO order is first.  This is only tracked
 232      for SSA names also serving as values (NAME == VALNUM).  */
 233   vn_avail *avail;
 234
 235   /* Unique identifier that all expressions with the same value have. */
 236   unsigned int value_id;
 237
 238   /* Whether the SSA_NAME has been processed at least once.  */
 239   unsigned visited : 1;
 240
 241   /* Whether the SSA_NAME has no defining statement and thus an
 242      insertion of such with EXPR as definition is required before
 243      a use can be created of it.  */
 244   unsigned needs_insertion : 1;
 245 } *vn_ssa_aux_t;
 246
 247 enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
 248
 249 /* Return the value numbering info for an SSA_NAME.  */
 250 bool has_VN_INFO (tree);
 251 extern vn_ssa_aux_t VN_INFO (tree);
 252 tree vn_get_expr_for (tree);
 253 void scc_vn_restore_ssa_info (void);
 254 vn_nary_op_t alloc_vn_nary_op_noinit (unsigned int, struct obstack *);
 255 unsigned int vn_nary_length_from_stmt (gimple *);
 256 void init_vn_nary_op_from_stmt (vn_nary_op_t, gassign *);
 257 hashval_t vn_nary_op_compute_hash (const vn_nary_op_t);
 258 tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
 259 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
 260                                tree, tree *, vn_nary_op_t *);
 261 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
 262                                        tree, tree *, tree, unsigned int);
 263 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, alias_set_type,
 264                                     tree, const vec<vn_reference_op_s> &);
 265 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
 266 tree vn_reference_lookup_pieces (tree, alias_set_type, alias_set_type, tree,
 267                                  vec<vn_reference_op_s> ,
 268                                  vn_reference_t *, vn_lookup_kind);
 269 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
 270                           tree * = NULL, tree = NULL_TREE, bool = false);
 271 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
 272 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, alias_set_type,
 273                                            poly_int64, poly_int64,
 274                                            tree, vec<vn_reference_op_s>,
 275                                            tree, unsigned int);
 276 void print_vn_reference_ops (FILE *, const vec<vn_reference_op_s>);
 277
 278 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
 279                     const_vn_nary_op_t const vno2);
 280 bool vn_nary_may_trap (vn_nary_op_t);
 281 bool vn_reference_may_trap (vn_reference_t);
 282 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
 283
 284 unsigned int get_max_value_id (void);
 285 unsigned int get_max_constant_value_id (void);
 286 unsigned int get_next_value_id (void);
 287 unsigned int get_next_constant_value_id (void);
 288 unsigned int get_constant_value_id (tree);
 289 unsigned int get_or_alloc_constant_value_id (tree);
 290
 291 /* Return true if V is a value id for a constant.  */
 292 inline bool
 293 value_id_constant_p (unsigned int v)
 294 {
 295   return (int)v < 0;
 296 }
 297
 298 tree fully_constant_vn_reference_p (vn_reference_t);
 299 tree vn_nary_simplify (vn_nary_op_t);
 300
 301 unsigned do_rpo_vn (function *, edge, bitmap,
 302                     /* iterate */ bool = false,
 303                     /* eliminate */ bool = true,
 304                     /* skip_entry_phis */ bool = false,
 305                     vn_lookup_kind = VN_WALKREWRITE);
 306
 307 /* Private interface for PRE.  */
 308 void run_rpo_vn (vn_lookup_kind);
 309 unsigned eliminate_with_rpo_vn (bitmap);
 310 void free_rpo_vn (void);
 311
 312 /* Valueize NAME if it is an SSA name, otherwise just return it.  This hook
 313    is initialized by run_scc_vn.  */
 314 extern tree (*vn_valueize) (tree);
 315
 316 /* Context that valueization should operate on.  */
 317 extern basic_block vn_context_bb;
 318
 319
 320 #endif /* TREE_SSA_SCCVN_H  */