151 lines
4.7 KiB
C++
151 lines
4.7 KiB
C++
/* Communication between registering jump thread requests and
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updating the SSA/CFG for jump threading.
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Copyright (C) 2013-2023 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef _TREE_SSA_THREADUPDATE_H
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#define _TREE_SSA_THREADUPDATE_H 1
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enum jump_thread_edge_type
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{
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EDGE_START_JUMP_THREAD,
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EDGE_COPY_SRC_BLOCK,
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EDGE_COPY_SRC_JOINER_BLOCK,
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EDGE_NO_COPY_SRC_BLOCK
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};
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// We keep the registered jump threading opportunities in this
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// vector as edge pairs (original_edge, target_edge).
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class jump_thread_edge
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{
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public:
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jump_thread_edge (edge e, jump_thread_edge_type t) : e (e), type (t) {}
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edge e;
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jump_thread_edge_type type;
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};
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class jump_thread_path_allocator
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{
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public:
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jump_thread_path_allocator ();
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~jump_thread_path_allocator ();
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jump_thread_edge *allocate_thread_edge (edge, jump_thread_edge_type);
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vec<jump_thread_edge *> *allocate_thread_path ();
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private:
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DISABLE_COPY_AND_ASSIGN (jump_thread_path_allocator);
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obstack m_obstack;
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};
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// Abstract class for the jump thread registry.
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//
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// When all candidates have been registered with
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// register_jump_thread(), thread_through_all_blocks() is called to
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// update the CFG.
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class jt_path_registry
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{
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public:
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jt_path_registry (bool backedge_threads);
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virtual ~jt_path_registry ();
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bool register_jump_thread (vec<jump_thread_edge *> *);
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bool thread_through_all_blocks (bool peel_loop_headers);
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void push_edge (vec<jump_thread_edge *> *path, edge, jump_thread_edge_type);
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vec<jump_thread_edge *> *allocate_thread_path ();
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void debug ();
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protected:
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void debug_path (FILE *, int pathno);
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vec<vec<jump_thread_edge *> *> m_paths;
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unsigned long m_num_threaded_edges;
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private:
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virtual bool update_cfg (bool peel_loop_headers) = 0;
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bool cancel_invalid_paths (vec<jump_thread_edge *> &path);
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jump_thread_path_allocator m_allocator;
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// True if threading through back edges is allowed. This is only
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// allowed in the generic copier in the backward threader.
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bool m_backedge_threads;
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DISABLE_COPY_AND_ASSIGN (jt_path_registry);
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};
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// Forward threader path registry using a custom BB copier.
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class fwd_jt_path_registry : public jt_path_registry
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{
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public:
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fwd_jt_path_registry ();
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~fwd_jt_path_registry ();
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void remove_jump_threads_including (edge);
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private:
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bool update_cfg (bool peel_loop_headers) override;
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void mark_threaded_blocks (bitmap threaded_blocks);
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bool thread_block_1 (basic_block, bool noloop_only, bool joiners);
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bool thread_block (basic_block, bool noloop_only);
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bool thread_through_loop_header (class loop *loop,
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bool may_peel_loop_headers);
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class redirection_data *lookup_redirection_data (edge e, enum insert_option);
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hash_table<struct removed_edges> *m_removed_edges;
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// Main data structure to hold information for duplicates of BB.
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hash_table<redirection_data> *m_redirection_data;
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};
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// Backward threader path registry using a generic BB copier.
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class back_jt_path_registry : public jt_path_registry
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{
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public:
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back_jt_path_registry ();
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private:
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bool update_cfg (bool peel_loop_headers) override;
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void adjust_paths_after_duplication (unsigned curr_path_num);
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bool duplicate_thread_path (edge entry, edge exit, basic_block *region,
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unsigned n_region, unsigned current_path_no);
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bool rewire_first_differing_edge (unsigned path_num, unsigned edge_num);
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};
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// Rather than search all the edges in jump thread paths each time DOM
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// is able to simply if control statement, we build a hash table with
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// the deleted edges. We only care about the address of the edge, not
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// its contents.
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struct removed_edges : nofree_ptr_hash<edge_def>
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{
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static hashval_t hash (edge e) { return htab_hash_pointer (e); }
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static bool equal (edge e1, edge e2) { return e1 == e2; }
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};
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extern unsigned int estimate_threading_killed_stmts (basic_block);
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enum bb_dom_status
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{
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/* BB does not dominate latch of the LOOP. */
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DOMST_NONDOMINATING,
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/* The LOOP is broken (there is no path from the header to its latch. */
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DOMST_LOOP_BROKEN,
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/* BB dominates the latch of the LOOP. */
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DOMST_DOMINATING
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};
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enum bb_dom_status determine_bb_domination_status (class loop *, basic_block);
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// In tree-ssa-dom.cc.
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extern void free_dom_edge_info (edge);
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#endif
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