gcc/tree-ssa-threadedge.h

   1 /* Header file for SSA jump threading.
   2    Copyright (C) 2013-2021 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   jt_state (class const_and_copies *,
  30             class avail_exprs_stack *,
  31             class evrp_range_analyzer *);
  32   void push (edge);
  33   void pop ();
  34   void register_equiv (tree dest, tree src, bool update_range = false);
  35   void register_equivs_on_edge (edge e);
  36   void record_ranges_from_stmt (gimple *stmt, bool temporary);
  37
  38 private:
  39   const_and_copies *m_copies;
  40   avail_exprs_stack *m_exprs;
  41   evrp_range_analyzer *m_evrp;
  42 };
  43
  44 // This is the high level threader.  The entry point is
  45 // thread_outgoing_edges(), which calculates and registers paths to be
  46 // threaded.  When all candidates have been registered,
  47 // thread_through_all_blocks() is called to actually change the CFG.
  48
  49 class jump_threader
  50 {
  51 public:
  52   jump_threader (class jump_threader_simplifier *, class jt_state *);
  53   ~jump_threader ();
  54   void thread_outgoing_edges (basic_block);
  55   void remove_jump_threads_including (edge_def *);
  56   bool thread_through_all_blocks (bool may_peel_loop_headers);
  57
  58 private:
  59   tree simplify_control_stmt_condition (edge, gimple *);
  60   tree simplify_control_stmt_condition_1 (edge,
  61                                           gimple *,
  62                                           tree op0,
  63                                           tree_code cond_code,
  64                                           tree op1,
  65                                           unsigned limit);
  66
  67   bool thread_around_empty_blocks (vec<class jump_thread_edge *> *path,
  68                                    edge, bitmap visited);
  69   int thread_through_normal_block (vec<jump_thread_edge *> *path,
  70                                    edge, bitmap visited);
  71   void thread_across_edge (edge);
  72   bool record_temporary_equivalences_from_phis (edge);
  73   gimple *record_temporary_equivalences_from_stmts_at_dest (edge);
  74
  75   // Dummy condition to avoid creating lots of throw away statements.
  76   gcond *dummy_cond;
  77
  78   class fwd_jt_path_registry *m_registry;
  79   jump_threader_simplifier *m_simplifier;
  80   jt_state *m_state;
  81 };
  82
  83 // Statement simplifier callback for the jump threader.
  84
  85 class jump_threader_simplifier
  86 {
  87 public:
  88   jump_threader_simplifier (class vr_values *v);
  89   virtual ~jump_threader_simplifier () { }
  90   virtual tree simplify (gimple *, gimple *, basic_block, jt_state *);
  91
  92 protected:
  93   vr_values *m_vr_values;
  94 };
  95
  96 extern void propagate_threaded_block_debug_into (basic_block, basic_block);
  97 extern bool single_succ_to_potentially_threadable_block (basic_block);
  98
  99 // ?? All this ssa_name_values stuff is the store of values for
 100 // avail_exprs_stack and const_and_copies, so it really belongs in the
 101 // jump_threader class.  However, it's probably not worth touching
 102 // this, since all this windable state is slated to go with the
 103 // ranger.
 104 extern vec<tree> ssa_name_values;
 105 #define SSA_NAME_VALUE(x) \
 106     (SSA_NAME_VERSION (x) < ssa_name_values.length () \
 107      ? ssa_name_values[SSA_NAME_VERSION (x)] \
 108      : NULL_TREE)
 109 extern void set_ssa_name_value (tree, tree);
 110
 111 #endif /* GCC_TREE_SSA_THREADEDGE_H */