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