gcc/tree-ssa-scopedtables.h

   1 /* Header file for SSA dominator optimizations.
   2    Copyright (C) 2013-2015 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.  */
 165   void record_const_or_copy (tree, tree);
 166
 167   /* Special entry point when we want to provide an explicit previous
 168      value for the first argument.  Try to get rid of this in the future.  */
 169   void record_const_or_copy (tree, tree, tree);
 170
 171  private:
 172   vec<tree> m_stack;
 173   const_and_copies& operator= (const const_and_copies&);
 174   const_and_copies (class const_and_copies &);
 175 };
 176
 177 void initialize_expr_from_cond (tree cond, struct hashable_expr *expr);
 178
 179 #endif /* GCC_TREE_SSA_SCOPED_TABLES_H */