gcc/tree-ssa-sccvn.h

   1 /* Tree SCC value numbering
   2    Copyright (C) 2007-2020 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.c  */
  25 bool expressions_equal_p (tree, tree);
  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.  */
 110   unsigned short clique;
 111   unsigned short base;
 112   unsigned reverse : 1;
 113   /* For storing TYPE_ALIGN for array ref element size computation.  */
 114   unsigned align : 6;
 115   /* Constant offset this op adds or -1 if it is variable.  */
 116   poly_int64_pod off;
 117   tree type;
 118   tree op0;
 119   tree op1;
 120   tree op2;
 121 } vn_reference_op_s;
 122 typedef vn_reference_op_s *vn_reference_op_t;
 123 typedef const vn_reference_op_s *const_vn_reference_op_t;
 124
 125 inline unsigned
 126 vn_ref_op_align_unit (vn_reference_op_t op)
 127 {
 128   return op->align ? ((unsigned)1 << (op->align - 1)) / BITS_PER_UNIT : 0;
 129 }
 130
 131 /* A reference operation in the hashtable is representation as
 132    the vuse, representing the memory state at the time of
 133    the operation, and a collection of operands that make up the
 134    addressing calculation.  If two vn_reference_t's have the same set
 135    of operands, they access the same memory location. We also store
 136    the resulting value number, and the hashcode.  */
 137
 138 typedef struct vn_reference_s
 139 {
 140   vn_reference_s *next;
 141   /* Unique identifier that all expressions with the same value have. */
 142   unsigned int value_id;
 143   hashval_t hashcode;
 144   tree vuse;
 145   alias_set_type set;
 146   tree type;
 147   vec<vn_reference_op_s> operands;
 148   tree result;
 149   tree result_vdef;
 150 } *vn_reference_t;
 151 typedef const struct vn_reference_s *const_vn_reference_t;
 152
 153 typedef struct vn_constant_s
 154 {
 155   unsigned int value_id;
 156   hashval_t hashcode;
 157   tree constant;
 158 } *vn_constant_t;
 159
 160 enum vn_kind { VN_NONE, VN_CONSTANT, VN_NARY, VN_REFERENCE, VN_PHI };
 161 enum vn_kind vn_get_stmt_kind (gimple *);
 162
 163 /* Hash the type TYPE using bits that distinguishes it in the
 164    types_compatible_p sense.  */
 165
 166 static inline hashval_t
 167 vn_hash_type (tree type)
 168 {
 169   return (INTEGRAL_TYPE_P (type)
 170           + (INTEGRAL_TYPE_P (type)
 171              ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
 172 }
 173
 174 /* Hash the constant CONSTANT with distinguishing type incompatible
 175    constants in the types_compatible_p sense.  */
 176
 177 static inline hashval_t
 178 vn_hash_constant_with_type (tree constant)
 179 {
 180   inchash::hash hstate;
 181   inchash::add_expr (constant, hstate);
 182   hstate.merge_hash (vn_hash_type (TREE_TYPE (constant)));
 183   return hstate.end ();
 184 }
 185
 186 /* Compare the constants C1 and C2 with distinguishing type incompatible
 187    constants in the types_compatible_p sense.  */
 188
 189 static inline bool
 190 vn_constant_eq_with_type (tree c1, tree c2)
 191 {
 192   return (expressions_equal_p (c1, c2)
 193           && types_compatible_p (TREE_TYPE (c1), TREE_TYPE (c2)));
 194 }
 195
 196 /* Instead of having a local availability lattice for each basic-block
 197    and availability at X defined as union of the local availabilities
 198    at X and its dominators we're turning this upside down and track
 199    availability per value given values are usually made available at very
 200    few points.
 201    So we have a chain of LOCATION, LEADER entries where LOCATION is
 202    specifying the basic-block LEADER is made available for VALUE.
 203    We prepend to this chain in RPO order thus for iteration we can simply
 204    remove the last entries.
 205    LOCATION is the basic-block index and LEADER is its SSA name version.  */
 206 struct vn_avail
 207 {
 208   vn_avail *next;
 209   /* The basic-block LEADER is made available.  */
 210   int location;
 211   /* The LEADER for the value we are chained on.  */
 212   int leader;
 213 };
 214
 215 typedef struct vn_ssa_aux
 216 {
 217   /* SSA name this vn_ssa_aux is associated with in the lattice.  */
 218   tree name;
 219   /* Value number. This may be an SSA name or a constant.  */
 220   tree valnum;
 221   /* Statements to insert if needs_insertion is true.  */
 222   gimple_seq expr;
 223
 224   /* AVAIL entries, last in RPO order is first.  This is only tracked
 225      for SSA names also serving as values (NAME == VALNUM).  */
 226   vn_avail *avail;
 227
 228   /* Unique identifier that all expressions with the same value have. */
 229   unsigned int value_id;
 230
 231   /* Whether the SSA_NAME has been processed at least once.  */
 232   unsigned visited : 1;
 233
 234   /* Whether the SSA_NAME has no defining statement and thus an
 235      insertion of such with EXPR as definition is required before
 236      a use can be created of it.  */
 237   unsigned needs_insertion : 1;
 238 } *vn_ssa_aux_t;
 239
 240 enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
 241
 242 /* Return the value numbering info for an SSA_NAME.  */
 243 bool has_VN_INFO (tree);
 244 extern vn_ssa_aux_t VN_INFO (tree);
 245 tree vn_get_expr_for (tree);
 246 void scc_vn_restore_ssa_info (void);
 247 tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
 248 tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
 249                                tree, tree *, vn_nary_op_t *);
 250 vn_nary_op_t vn_nary_op_insert_pieces (unsigned int, enum tree_code,
 251                                        tree, tree *, tree, unsigned int);
 252 bool ao_ref_init_from_vn_reference (ao_ref *, alias_set_type, tree,
 253                                     vec<vn_reference_op_s> );
 254 vec<vn_reference_op_s> vn_reference_operands_for_lookup (tree);
 255 tree vn_reference_lookup_pieces (tree, alias_set_type, tree,
 256                                  vec<vn_reference_op_s> ,
 257                                  vn_reference_t *, vn_lookup_kind);
 258 tree vn_reference_lookup (tree, tree, vn_lookup_kind, vn_reference_t *, bool,
 259                           tree * = NULL);
 260 void vn_reference_lookup_call (gcall *, vn_reference_t *, vn_reference_t);
 261 vn_reference_t vn_reference_insert_pieces (tree, alias_set_type, tree,
 262                                            vec<vn_reference_op_s> ,
 263                                            tree, unsigned int);
 264
 265 bool vn_nary_op_eq (const_vn_nary_op_t const vno1,
 266                     const_vn_nary_op_t const vno2);
 267 bool vn_nary_may_trap (vn_nary_op_t);
 268 bool vn_reference_may_trap (vn_reference_t);
 269 bool vn_reference_eq (const_vn_reference_t const, const_vn_reference_t const);
 270 unsigned int get_max_value_id (void);
 271 unsigned int get_next_value_id (void);
 272 unsigned int get_constant_value_id (tree);
 273 unsigned int get_or_alloc_constant_value_id (tree);
 274 bool value_id_constant_p (unsigned int);
 275 tree fully_constant_vn_reference_p (vn_reference_t);
 276 tree vn_nary_simplify (vn_nary_op_t);
 277
 278 unsigned do_rpo_vn (function *, edge, bitmap);
 279 void run_rpo_vn (vn_lookup_kind);
 280 unsigned eliminate_with_rpo_vn (bitmap);
 281 void free_rpo_vn (void);
 282
 283 /* Valueize NAME if it is an SSA name, otherwise just return it.  This hook
 284    is initialized by run_scc_vn.  */
 285 extern tree (*vn_valueize) (tree);
 286
 287 /* Context that valueization should operate on.  */
 288 extern basic_block vn_context_bb;
 289
 290
 291 #endif /* TREE_SSA_SCCVN_H  */