gcc/tree-ssa-threadedge.h

   1 /* Header file for SSA jump threading.
   2    Copyright (C) 2013-2022 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_THREADEDGE_H
  21 #define GCC_TREE_SSA_THREADEDGE_H
  22
  23 // Class used to maintain path state in the jump threader and pass it
  24 // to the jump threader simplifier.
  25
  26 class jt_state
  27 {
  28 public:
  29   virtual ~jt_state () { }
  30   virtual void push (edge);
  31   virtual void pop ();
  32   virtual void register_equiv (tree dest, tree src, bool update_range);
  33   virtual void register_equivs_edge (edge e);
  34   virtual void register_equivs_stmt (gimple *, basic_block,
  35                                      class jt_simplifier *);
  36   virtual void record_ranges_from_stmt (gimple *stmt, bool temporary);
  37   void get_path (vec<basic_block> &);
  38   void append_path (basic_block);
  39   void dump (FILE *);
  40   void debug ();
  41
  42 private:
  43   auto_vec<basic_block> m_blocks;
  44   static const basic_block BB_MARKER;
  45 };
  46
  47 // Statement simplifier callback for the jump threader.
  48
  49 class jt_simplifier
  50 {
  51 public:
  52   virtual ~jt_simplifier () { }
  53   virtual tree simplify (gimple *, gimple *, basic_block, jt_state *) = 0;
  54 };
  55
  56 class hybrid_jt_state : public jt_state
  57 {
  58 private:
  59   void register_equivs_stmt (gimple *, basic_block, jt_simplifier *) override
  60   {
  61     // Ranger has no need to simplify anything.
  62   }
  63 };
  64
  65 class hybrid_jt_simplifier : public jt_simplifier
  66 {
  67 public:
  68   hybrid_jt_simplifier (class gimple_ranger *r, class path_range_query *q);
  69   tree simplify (gimple *stmt, gimple *, basic_block, jt_state *) override;
  70
  71 private:
  72   void compute_exit_dependencies (bitmap dependencies,
  73                                   const vec<basic_block> &path,
  74                                   gimple *stmt);
  75
  76   gimple_ranger *m_ranger;
  77   path_range_query *m_query;
  78 };
  79
  80 // This is the high level threader.  The entry point is
  81 // thread_outgoing_edges(), which calculates and registers paths to be
  82 // threaded.  When all candidates have been registered,
  83 // thread_through_all_blocks() is called to actually change the CFG.
  84
  85 class jump_threader
  86 {
  87 public:
  88   jump_threader (jt_simplifier *, class jt_state *);
  89   ~jump_threader ();
  90   void thread_outgoing_edges (basic_block);
  91   void remove_jump_threads_including (edge_def *);
  92   bool thread_through_all_blocks (bool may_peel_loop_headers);
  93
  94 private:
  95   tree simplify_control_stmt_condition (edge, gimple *);
  96   tree simplify_control_stmt_condition_1 (edge,
  97                                           gimple *,
  98                                           tree op0,
  99                                           tree_code cond_code,
 100                                           tree op1,
 101                                           unsigned limit);
 102
 103   bool thread_around_empty_blocks (vec<class jump_thread_edge *> *path,
 104                                    edge, bitmap visited);
 105   int thread_through_normal_block (vec<jump_thread_edge *> *path,
 106                                    edge, bitmap visited);
 107   void thread_across_edge (edge);
 108   bool record_temporary_equivalences_from_phis (edge);
 109   gimple *record_temporary_equivalences_from_stmts_at_dest (edge);
 110
 111   // Dummy condition to avoid creating lots of throw away statements.
 112   gcond *dummy_cond;
 113
 114   class fwd_jt_path_registry *m_registry;
 115   jt_simplifier *m_simplifier;
 116   jt_state *m_state;
 117 };
 118
 119 extern void propagate_threaded_block_debug_into (basic_block, basic_block);
 120 extern bool single_succ_to_potentially_threadable_block (basic_block);
 121
 122 // ?? All this ssa_name_values stuff is the store of values for
 123 // avail_exprs_stack and const_and_copies, so it really belongs in the
 124 // jump_threader class.  However, it's probably not worth touching
 125 // this, since all this windable state is slated to go with the
 126 // ranger.
 127 extern vec<tree> ssa_name_values;
 128 #define SSA_NAME_VALUE(x) \
 129     (SSA_NAME_VERSION (x) < ssa_name_values.length () \
 130      ? ssa_name_values[SSA_NAME_VERSION (x)] \
 131      : NULL_TREE)
 132 extern void set_ssa_name_value (tree, tree);
 133
 134 #endif /* GCC_TREE_SSA_THREADEDGE_H */