gcc/value-query.h

   1 /* Support routines for value queries.
   2    Copyright (C) 2020-2021 Free Software Foundation, Inc.
   3    Contributed by Aldy Hernandez <aldyh@redhat.com> and
   4    Andrew Macleod <amacleod@redhat.com>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 3, or (at your option)
  11 any later version.
  12
  13 GCC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef GCC_QUERY_H
  23 #define GCC_QUERY_H
  24
  25 // The value_query class is used by optimization passes that require
  26 // valueizing SSA names in terms of a tree value, but have no neeed
  27 // for ranges.
  28 //
  29 // value_of_expr must be provided.  The default for value_on_edge and
  30 // value_of_stmt is to call value_of_expr.
  31 //
  32 // This implies the valuation is global in nature.  If a pass can make
  33 // use of more specific information, it can override the other queries.
  34 //
  35 // Proper usage of the correct query in passes will enable other
  36 // valuation mechanisms to produce more precise results.
  37
  38 class value_query
  39 {
  40 public:
  41   value_query () { }
  42   // Return the singleton expression for NAME at a gimple statement,
  43   // or NULL if none found.
  44   virtual tree value_of_expr (tree name, gimple * = NULL) = 0;
  45   // Return the singleton expression for NAME at an edge, or NULL if
  46   // none found.
  47   virtual tree value_on_edge (edge, tree name);
  48   // Return the singleton expression for the LHS of a gimple
  49   // statement, assuming an (optional) initial value of NAME.  Returns
  50   // NULL if none found.
  51   //
  52   // Note that this method calculates the range the LHS would have
  53   // *after* the statement has executed.
  54   virtual tree value_of_stmt (gimple *, tree name = NULL);
  55
  56 private:
  57   DISABLE_COPY_AND_ASSIGN (value_query);
  58 };
  59
  60 // The range_query class is used by optimization passes which are
  61 // range aware.
  62 //
  63 // range_of_expr must be provided.  The default for range_on_edge and
  64 // range_of_stmt is to call range_of_expr.  If a pass can make use of
  65 // more specific information, then it can override the other queries.
  66 //
  67 // The default for the value_* routines is to call the equivalent
  68 // range_* routines, check if the range is a singleton, and return it
  69 // if so.
  70 //
  71 // The get_value_range method is currently provided for compatibility
  72 // with vr-values.  It will be deprecated when possible.
  73
  74 class range_query : public value_query
  75 {
  76 public:
  77   range_query ();
  78   virtual ~range_query ();
  79
  80   virtual tree value_of_expr (tree name, gimple * = NULL) OVERRIDE;
  81   virtual tree value_on_edge (edge, tree name) OVERRIDE;
  82   virtual tree value_of_stmt (gimple *, tree name = NULL) OVERRIDE;
  83
  84   // These are the range equivalents of the value_* methods.  Instead
  85   // of returning a singleton, they calculate a range and return it in
  86   // R.  TRUE is returned on success or FALSE if no range was found.
  87   //
  88   // Note that range_of_expr must always return TRUE unless ranges are
  89   // unsupported for NAME's type (supports_type_p is false).
  90   virtual bool range_of_expr (irange &r, tree name, gimple * = NULL) = 0;
  91   virtual bool range_on_edge (irange &r, edge, tree name);
  92   virtual bool range_of_stmt (irange &r, gimple *, tree name = NULL);
  93
  94   // DEPRECATED: This method is used from vr-values.  The plan is to
  95   // rewrite all uses of it to the above API.
  96   virtual const class value_range_equiv *get_value_range (const_tree,
  97                                                           gimple * = NULL);
  98
  99 protected:
 100   class value_range_equiv *allocate_value_range_equiv ();
 101   void free_value_range_equiv (class value_range_equiv *);
 102
 103 private:
 104   class equiv_allocator *equiv_alloc;
 105 };
 106
 107 #endif // GCC_QUERY_H