gcc/tree-ssa-sccvn.h

   1 /* Tree SCC value numbering
   2    Copyright (C) 2007-2022 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 static 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_pod 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   tree type;
 149   unsigned punned : 1;
 150   vec<vn_reference_op_s> operands;
 151   tree result;
 152   tree result_vdef;
 153 } *vn_reference_t;
 154 typedef const struct vn_reference_s *const_vn_reference_t;
 155
 156 typedef struct vn_constant_s
 157 {
 158   unsigned int value_id;
 159   hashval_t hashcode;
 160   tree constant;
 161 } *vn_constant_t;
 162
 163 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
 164 enum vn_kind vn_get_stmt_kind (gimple *);
 165
 166 /* Hash the type TYPE using bits that distinguishes it in the
 167    types_compatible_p sense.  */
 168
 169 static inline hashval_t
 170 vn_hash_type (tree type)
 171 {
 172   return (INTEGRAL_TYPE_P (type)
 173           + (INTEGRAL_TYPE_P (type)
 174              ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
 175 }
 176
 177 /* Hash the constant CONSTANT with distinguishing type incompatible
 178    constants in the types_compatible_p sense.  */
 179
 180 static inline hashval_t
 181 vn_hash_constant_with_type (tree constant)
 182 {
 183   inchash::hash hstate;
 184   inchash::add_expr (constant, hstate);
 185   hstate.merge_hash (vn_hash_type (TREE_TYPE (constant)));
 186   return hstate.end ();
 187 }
 188
 189 /* Compare the constants C1 and C2 with distinguishing type incompatible
 190    constants in the types_compatible_p sense.  */
 191
 192 static inline bool
 193 vn_constant_eq_with_type (tree c1, tree c2)
 194 {
 195   return (expressions_equal_p (c1, c2)
 196           && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
 197 }
 198
 199 /* Instead of having a local availability lattice for each basic-block
 200    and availability at X defined as union of the local availabilities
 201    at X and its dominators we're turning this upside down and track
 202    availability per value given values are usually made available at very
 203    few points.
 204    So we have a chain of LOCATION, LEADER entries where LOCATION is
 205    specifying the basic-block LEADER is made available for VALUE.
 206    We prepend to this chain in RPO order thus for iteration we can simply
 207    remove the last entries.
 208    LOCATION is the basic-block index and LEADER is its SSA name version.  */
 209 struct vn_avail
 210 {
 211   vn_avail *next;
 212   /* The basic-block LEADER is made available.  */
 213   int location;
 214   /* The LEADER for the value we are chained on.  */
 215   int leader;
 216   /* The previous value we pushed a avail record to.  */
 217   struct vn_ssa_aux *next_undo;
 218 };
 219
 220 typedef struct vn_ssa_aux
 221 {
 222   /* SSA name this vn_ssa_aux is associated with in the lattice.  */
 223   tree name;
 224   /* Value number. This may be an SSA name or a constant.  */
 225   tree valnum;
 226   /* Statements to insert if needs_insertion is true.  */
 227   gimple_seq expr;
 228
 229   /* AVAIL entries, last in RPO order is first.  This is only tracked
 230      for SSA names also serving as values (NAME == VALNUM).  */
 231   vn_avail *avail;
 232
 233   /* Unique identifier that all expressions with the same value have. */
 234   unsigned int value_id;
 235
 236   /* Whether the SSA_NAME has been processed at least once.  */
 237   unsigned visited : 1;
 238
 239   /* Whether the SSA_NAME has no defining statement and thus an
 240      insertion of such with EXPR as definition is required before
 241      a use can be created of it.  */
 242   unsigned needs_insertion : 1;
 243 } *vn_ssa_aux_t;
 244
 245 enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
 246
 247 /* Return the value numbering info for an SSA_NAME.  */
 248 bool has_VN_INFO (tree);
 249 extern vn_ssa_aux_t VN_INFO (tree);
 250 tree vn_get_expr_for (tree);
 251 void scc_vn_restore_ssa_info (void);
 252 vn_nary_op_t alloc_vn_nary_op_noinit (unsigned int, struct obstack *);
 253 unsigned int vn_nary_length_from_stmt (gimple *);
 254 void init_vn_nary_op_from_stmt (vn_nary_op_t, gassign *);
 255 hashval_t vn_nary_op_compute_hash (const vn_nary_op_t);
 256 tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
 257 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
 258                                tree, tree *, vn_nary_op_t *);
 259 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
 260                                        tree, tree *, tree, unsigned int);
 261 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, alias_set_type,
 262                                     tree, const vec<vn_reference_op_s> &);
 263 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
 264 tree vn_reference_lookup_pieces (tree, alias_set_type, alias_set_type, tree,
 265                                  vec<vn_reference_op_s> ,
 266                                  vn_reference_t *, vn_lookup_kind);
 267 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
 268                           tree * = NULL, tree = NULL_TREE, bool = false);
 269 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
 270 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, alias_set_type,
 271                                            tree, vec<vn_reference_op_s>,
 272                                            tree, unsigned int);
 273 void print_vn_reference_ops (FILE *, const vec<vn_reference_op_s>);
 274
 275 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
 276                     const_vn_nary_op_t const vno2);
 277 bool vn_nary_may_trap (vn_nary_op_t);
 278 bool vn_reference_may_trap (vn_reference_t);
 279 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
 280
 281 unsigned int get_max_value_id (void);
 282 unsigned int get_max_constant_value_id (void);
 283 unsigned int get_next_value_id (void);
 284 unsigned int get_next_constant_value_id (void);
 285 unsigned int get_constant_value_id (tree);
 286 unsigned int get_or_alloc_constant_value_id (tree);
 287
 288 /* Return true if V is a value id for a constant.  */
 289 static inline bool
 290 value_id_constant_p (unsigned int v)
 291 {
 292   return (int)v < 0;
 293 }
 294
 295 tree fully_constant_vn_reference_p (vn_reference_t);
 296 tree vn_nary_simplify (vn_nary_op_t);
 297
 298 unsigned do_rpo_vn (function *, edge, bitmap,
 299                     /* iterate */ bool = false,
 300                     /* eliminate */ bool = true,
 301                     vn_lookup_kind = VN_WALKREWRITE);
 302
 303 /* Private interface for PRE.  */
 304 void run_rpo_vn (vn_lookup_kind);
 305 unsigned eliminate_with_rpo_vn (bitmap);
 306 void free_rpo_vn (void);
 307
 308 /* Valueize NAME if it is an SSA name, otherwise just return it.  This hook
 309    is initialized by run_scc_vn.  */
 310 extern tree (*vn_valueize) (tree);
 311
 312 /* Context that valueization should operate on.  */
 313 extern basic_block vn_context_bb;
 314
 315
 316 #endif /* TREE_SSA_SCCVN_H  */