gcc/gimple-range-infer.h

   1 /* Header file for gimple range inference.
   2    Copyright (C) 2022-2025 Free Software Foundation, Inc.
   3    Contributed by Andrew MacLeod <amacleod@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  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 GCC_GIMPLE_RANGE_SIDE_H
  22 #define GCC_GIMPLE_RANGE_SIDE_H
  23
  24 // Inferred ranges are ranges which are applied to use operands as a by product
  25 // of executing an operation.
  26
  27 // This class manages an on-demand summary of inferred ranges for a statement.
  28 // It can be instantiated as required and provides a list of inferred ranges.
  29 // New inferred ranges should be added in the constructor of this class.
  30 //
  31 // There are 2 main instantiations.
  32 // gimple_range_infer (gimple *s, range_query *q, bool use_range_ops)
  33 //   S is the statement being queried.
  34 //   Q is a range-query object which is used to resolve any ranges that
  35 //      might be required.  This defaults to NULL which maps to the
  36 //      global_range_query, which is what most passes will want.
  37 //      Ranger internally will pass the cache's range-query which is a
  38 //      read-only query and prevents any additional lookup.
  39 //   USE_RANGEOPS is a boolean flag which defaults to false.  if TRUE,
  40 //      range-ops is invoked to see if any additional side effects are seen
  41 //      based on the stmt.  ie .x = y * 2 will reigster a side effect for Y
  42 //      which is [-INF/2 , +INF/2].  It is not on by default because it
  43 //      is a relatively expensive operation to do on every statement, and
  44 //      ranger will already incorporate that range for Y via GORI most of the
  45 //      time that it matters.  Individual passes may have use for it however.
  46 //      PR 113879 is an example where this can be of use.
  47 //
  48 // gimple_range_infer (tree name, vrange &r)
  49 // This instantiation simply create an inferred range record directly.
  50 //   NAME is the SSA_NAME to create the record for
  51 //   R is the range for NAME.
  52 //
  53 // Once a gimple_infer_range record has been created, the API is simple:
  54 //   num ()    - The number of inferred ranges in this record.
  55 //   name (i)  - The i'th SSA_NAME in this record.
  56 //   range (i) - The range of the i'th SSA_NAME.
  57
  58 class gimple_infer_range
  59 {
  60 public:
  61   gimple_infer_range (gimple *s, range_query *q = NULL,
  62                       bool use_rangeops = false);
  63   gimple_infer_range (tree name, vrange &r);
  64   inline unsigned num () const { return num_args; }
  65   inline tree name (unsigned index) const
  66     { gcc_checking_assert (index < num_args); return m_names[index]; }
  67   inline const vrange& range (unsigned index) const
  68     { gcc_checking_assert (index < num_args); return m_ranges[index]; }
  69 private:
  70   void add_range (tree name, vrange &range);
  71   void add_nonzero (tree name);
  72   void check_assume_func (gcall *call);
  73   unsigned num_args;
  74   static const int size_limit = 10;
  75   tree m_names[size_limit];
  76   value_range m_ranges[size_limit];
  77   inline void bump_index () { if (num_args < size_limit - 1) num_args++; }
  78   friend class non_null_wrapper;
  79 };
  80
  81 // This is the basic infer oracle API.  Default functionaility does nothing.
  82
  83 class infer_range_oracle
  84 {
  85 public:
  86   infer_range_oracle () { }
  87   virtual ~infer_range_oracle () { }
  88   virtual void add_ranges (gimple *, gimple_infer_range &) { }
  89   virtual bool has_range_p (basic_block, tree = NULL_TREE) { return false; }
  90   virtual bool maybe_adjust_range (vrange &, tree, basic_block)
  91       { return false; }
  92 };
  93
  94 // This class manages a list of inferred ranges for each basic block.
  95 // As inferences are made, they can be registered to a block and later
  96 // queried via a DOM search.
  97 // When DO_SEARCH is TRUE,  immediate uses chains are followed the first time
  98 // a name is referenced and block populated if there are any inferred ranges.
  99 // range_query Q is the range_query to use for any range lookups. It defaults
 100 // to NULL which maps to the global_range_query.  This is what most passes
 101 // will want to use. Ranger invokes it with the cache's internal query which
 102 // can provide better ranges during a DOM walk.
 103 //
 104 // add_ranges is used to add inferred range IR assocaited with stmt S.
 105 // has_range_p is used to check if NAME has an inferred range in block BB.
 106 // maybe_adjust_range will adjust the range R to incorporate any inferred
 107 //   range NAME may have in block BB.  If there are on inferred ranges in
 108 //   block BB, then R will be unchanged, otherwise the ranges are intersected.
 109
 110 class infer_range_manager : public infer_range_oracle
 111 {
 112 public:
 113   infer_range_manager (bool do_search, range_query *q = NULL);
 114   virtual ~infer_range_manager ();
 115   virtual void add_ranges (gimple *s, gimple_infer_range &ir);
 116   virtual bool has_range_p (basic_block bb, tree name = NULL_TREE);
 117   virtual bool maybe_adjust_range (vrange &r, tree name, basic_block bb);
 118 private:
 119   void add_range (tree name, gimple *s, const vrange &r);
 120   void add_nonzero (tree name, gimple *s);
 121   class exit_range_head
 122   {
 123   public:
 124     bitmap m_names;             // list of names with an outgoing range.
 125     class exit_range *head;
 126     int m_num_ranges;
 127     exit_range *find_ptr (tree name);
 128   };
 129   void register_all_uses (tree name);
 130   vec <exit_range_head> m_on_exit;
 131   const vrange &get_nonzero (tree name);
 132   vec <vrange *> m_nonzero;
 133   bitmap m_seen;
 134   bitmap_obstack m_bitmaps;
 135   struct obstack m_list_obstack;
 136   class vrange_allocator *m_range_allocator;
 137   range_query *m_query;
 138 };
 139 #endif // GCC_GIMPLE_RANGE_SIDE_H