gcc/tree-ssa-threadupdate.h

   1 /* Communication between registering jump thread requests and
   2    updating the SSA/CFG for jump threading.
   3    Copyright (C) 2013-2021 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License 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 _TREE_SSA_THREADUPDATE_H
  22 #define _TREE_SSA_THREADUPDATE_H 1
  23
  24 enum jump_thread_edge_type
  25 {
  26   EDGE_START_JUMP_THREAD,
  27   EDGE_FSM_THREAD,
  28   EDGE_COPY_SRC_BLOCK,
  29   EDGE_COPY_SRC_JOINER_BLOCK,
  30   EDGE_NO_COPY_SRC_BLOCK
  31 };
  32
  33 // We keep the registered jump threading opportunities in this
  34 // vector as edge pairs (original_edge, target_edge).
  35
  36 class jump_thread_edge
  37 {
  38 public:
  39   jump_thread_edge (edge e, jump_thread_edge_type t) : e (e), type (t) {}
  40
  41   edge e;
  42   jump_thread_edge_type type;
  43 };
  44
  45 class jump_thread_path_allocator
  46 {
  47 public:
  48   jump_thread_path_allocator ();
  49   ~jump_thread_path_allocator ();
  50   jump_thread_edge *allocate_thread_edge (edge, jump_thread_edge_type);
  51   vec<jump_thread_edge *> *allocate_thread_path ();
  52 private:
  53   DISABLE_COPY_AND_ASSIGN (jump_thread_path_allocator);
  54   obstack m_obstack;
  55 };
  56
  57 // This is the underlying jump thread registry.  When all candidates
  58 // have been registered with register_jump_thread(),
  59 // thread_through_all_blocks() is called to actually change the CFG.
  60
  61 class jump_thread_path_registry
  62 {
  63 public:
  64   jump_thread_path_registry ();
  65   ~jump_thread_path_registry ();
  66   bool register_jump_thread (vec<jump_thread_edge *> *);
  67   void remove_jump_threads_including (edge);
  68   bool thread_through_all_blocks (bool);
  69   jump_thread_edge *allocate_thread_edge (edge e, jump_thread_edge_type t);
  70   vec<jump_thread_edge *> *allocate_thread_path ();
  71   void dump ();
  72
  73 private:
  74   void debug_path (FILE *, int pathno);
  75   void mark_threaded_blocks (bitmap threaded_blocks);
  76   bool rewire_first_differing_edge (unsigned path_num, unsigned edge_num);
  77   void adjust_paths_after_duplication (unsigned curr_path_num);
  78   bool duplicate_thread_path (edge entry,
  79                               edge exit,
  80                               basic_block *region,
  81                               unsigned n_region,
  82                               unsigned current_path_no);
  83   bool thread_block_1 (basic_block, bool noloop_only, bool joiners);
  84   bool thread_block (basic_block, bool noloop_only);
  85   bool thread_through_loop_header (class loop *loop,
  86                                    bool may_peel_loop_headers);
  87   class redirection_data *lookup_redirection_data (edge e, enum insert_option);
  88
  89   vec<vec<jump_thread_edge *> *> m_paths;
  90
  91   hash_table<struct removed_edges> *m_removed_edges;
  92
  93   // Main data structure to hold information for duplicates of BB.
  94   hash_table<redirection_data> *m_redirection_data;
  95
  96   // Jump threading statistics.
  97   unsigned long m_num_threaded_edges;
  98
  99   jump_thread_path_allocator m_allocator;
 100 };
 101
 102 // Rather than search all the edges in jump thread paths each time DOM
 103 // is able to simply if control statement, we build a hash table with
 104 // the deleted edges.  We only care about the address of the edge, not
 105 // its contents.
 106 struct removed_edges : nofree_ptr_hash<edge_def>
 107 {
 108   static hashval_t hash (edge e) { return htab_hash_pointer (e); }
 109   static bool equal (edge e1, edge e2) { return e1 == e2; }
 110 };
 111
 112 extern unsigned int estimate_threading_killed_stmts (basic_block);
 113
 114 enum bb_dom_status
 115 {
 116   /* BB does not dominate latch of the LOOP.  */
 117   DOMST_NONDOMINATING,
 118   /* The LOOP is broken (there is no path from the header to its latch.  */
 119   DOMST_LOOP_BROKEN,
 120   /* BB dominates the latch of the LOOP.  */
 121   DOMST_DOMINATING
 122 };
 123
 124 enum bb_dom_status determine_bb_domination_status (class loop *, basic_block);
 125
 126 // In tree-ssa-dom.c.
 127 extern void free_dom_edge_info (edge);
 128
 129 #endif