gcc/tree-ssa-scopedtables.h

   1 /* Header file for SSA dominator optimizations.
   2    Copyright (C) 2013-2017 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_TREE_SSA_SCOPED_TABLES_H
  21 #define GCC_TREE_SSA_SCOPED_TABLES_H
  22
  23 /* Representation of a "naked" right-hand-side expression, to be used
  24    in recording available expressions in the expression hash table.  */
  25
  26 enum expr_kind
  27 {
  28   EXPR_SINGLE,
  29   EXPR_UNARY,
  30   EXPR_BINARY,
  31   EXPR_TERNARY,
  32   EXPR_CALL,
  33   EXPR_PHI
  34 };
  35
  36 struct hashable_expr
  37 {
  38   tree type;
  39   enum expr_kind kind;
  40   union {
  41     struct { tree rhs; } single;
  42     struct { enum tree_code op;  tree opnd; } unary;
  43     struct { enum tree_code op;  tree opnd0, opnd1; } binary;
  44     struct { enum tree_code op;  tree opnd0, opnd1, opnd2; } ternary;
  45     struct { gcall *fn_from; bool pure; size_t nargs; tree *args; } call;
  46     struct { size_t nargs; tree *args; } phi;
  47   } ops;
  48 };
  49
  50 /* Structure for entries in the expression hash table.  */
  51
  52 typedef class expr_hash_elt * expr_hash_elt_t;
  53
  54 class expr_hash_elt
  55 {
  56  public:
  57   expr_hash_elt (gimple *, tree);
  58   expr_hash_elt (tree);
  59   expr_hash_elt (struct hashable_expr *, tree);
  60   expr_hash_elt (class expr_hash_elt &);
  61   ~expr_hash_elt ();
  62   void print (FILE *);
  63   tree vop (void) { return m_vop; }
  64   tree lhs (void) { return m_lhs; }
  65   struct hashable_expr *expr (void) { return &m_expr; }
  66   expr_hash_elt *stamp (void) { return m_stamp; }
  67   hashval_t hash (void) { return m_hash; }
  68
  69  private:
  70   /* The expression (rhs) we want to record.  */
  71   struct hashable_expr m_expr;
  72
  73   /* The value (lhs) of this expression.  */
  74   tree m_lhs;
  75
  76   /* The virtual operand associated with the nearest dominating stmt
  77      loading from or storing to expr.  */
  78   tree m_vop;
  79
  80   /* The hash value for RHS.  */
  81   hashval_t m_hash;
  82
  83   /* A unique stamp, typically the address of the hash
  84      element itself, used in removing entries from the table.  */
  85   struct expr_hash_elt *m_stamp;
  86
  87   /* We should never be making assignments between objects in this class.
  88      Though it might allow us to exploit C++11 move semantics if we
  89      defined the move constructor and move assignment operator.  */
  90   expr_hash_elt& operator= (const expr_hash_elt&);
  91 };
  92
  93 /* Hashtable helpers.  */
  94
  95 struct expr_elt_hasher : pointer_hash <expr_hash_elt>
  96 {
  97   static inline hashval_t hash (const value_type &p)
  98     { return p->hash (); }
  99   static bool equal (const value_type &, const compare_type &);
 100   static inline void remove (value_type &element)
 101     { delete element; }
 102 };
 103
 104
 105 /* This class defines a unwindable expression equivalence table
 106    layered on top of the expression hash table.
 107
 108    Essentially it's just a stack of available expression value pairs with
 109    a special marker (NULL, NULL) to indicate unwind points.   */
 110
 111 class avail_exprs_stack
 112 {
 113  public:
 114   /* We need access to the AVAIL_EXPR hash table so that we can
 115      remove entries from the hash table when unwinding the stack.  */
 116   avail_exprs_stack (hash_table<expr_elt_hasher> *table)
 117     { m_stack.create (20); m_avail_exprs = table; }
 118   ~avail_exprs_stack (void) { m_stack.release (); }
 119
 120   /* Push the unwinding marker onto the stack.  */
 121   void push_marker (void) { record_expr (NULL, NULL, 'M'); }
 122
 123   /* Restore the AVAIL_EXPRs table to its state when the last marker
 124      was pushed.  */
 125   void pop_to_marker (void);
 126
 127   /* Record a single available expression that can be unwound.  */
 128   void record_expr (expr_hash_elt_t, expr_hash_elt_t, char);
 129
 130   /* Get the underlying hash table.  Would this be better as
 131      class inheritance?  */
 132   hash_table<expr_elt_hasher> *avail_exprs (void)
 133     { return m_avail_exprs; }
 134
 135  private:
 136   vec<std::pair<expr_hash_elt_t, expr_hash_elt_t> > m_stack;
 137   hash_table<expr_elt_hasher> *m_avail_exprs;
 138
 139   /* We do not allow copying this object or initializing one
 140      from another.  */
 141   avail_exprs_stack& operator= (const avail_exprs_stack&);
 142   avail_exprs_stack (class avail_exprs_stack &);
 143 };
 144
 145 /* This class defines an unwindable const/copy equivalence table
 146    layered on top of SSA_NAME_VALUE/set_ssa_name_value.
 147
 148    Essentially it's just a stack of name,prev value pairs with a
 149    special marker (NULL) to indicate unwind points.  */
 150
 151 class const_and_copies
 152 {
 153  public:
 154   const_and_copies (void) { m_stack.create (20); };
 155   ~const_and_copies (void) { m_stack.release (); }
 156
 157   /* Push the unwinding marker onto the stack.  */
 158   void push_marker (void) { m_stack.safe_push (NULL_TREE); }
 159
 160   /* Restore the const/copies table to its state when the last marker
 161      was pushed.  */
 162   void pop_to_marker (void);
 163
 164   /* Record a single const/copy pair that can be unwound.  This version
 165      may follow the value chain for the RHS.  */
 166   void record_const_or_copy (tree, tree);
 167
 168   /* Record a single const/copy pair that can be unwound.  This version
 169      does not follow the value chain for the RHS.  */
 170   void record_const_or_copy_raw (tree, tree, tree);
 171
 172   /* Special entry point when we want to provide an explicit previous
 173      value for the first argument.  Try to get rid of this in the future.
 174
 175      This version may also follow the value chain for the RHS.  */
 176   void record_const_or_copy (tree, tree, tree);
 177
 178  private:
 179   vec<tree> m_stack;
 180   const_and_copies& operator= (const const_and_copies&);
 181   const_and_copies (class const_and_copies &);
 182 };
 183
 184 void initialize_expr_from_cond (tree cond, struct hashable_expr *expr);
 185
 186 #endif /* GCC_TREE_SSA_SCOPED_TABLES_H */