GCC Middle and Back End API Reference
back_threader_registry Class Reference
Inheritance diagram for back_threader_registry:
Collaboration diagram for back_threader_registry:

Public Member Functions

bool register_path (const vec< basic_block > &, edge taken)
 
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 Member Functions

void debug_path (FILE *, int pathno)
 

Protected Attributes

vec< vec< jump_thread_edge * > * > m_paths
 
unsigned long m_num_threaded_edges
 

Private Member Functions

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)
 
bool cancel_invalid_paths (vec< jump_thread_edge * > &path)
 
 DISABLE_COPY_AND_ASSIGN (jt_path_registry)
 

Private Attributes

jump_thread_path_allocator m_allocator
 
bool m_backedge_threads
 

Detailed Description

SSA Jump Threading Copyright (C) 2005-2025 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/>.

Member Function Documentation

◆ adjust_paths_after_duplication()

void back_jt_path_registry::adjust_paths_after_duplication ( unsigned curr_path_num)
privateinherited
After a path has been jump threaded, adjust the remaining paths that are subsets of this path, so these paths can be safely threaded within the context of the new threaded path. For example, suppose we have just threaded: 5 -> 6 -> 7 -> 8 -> 12 => 5 -> 6' -> 7' -> 8' -> 12' And we have an upcoming threading candidate: 5 -> 6 -> 7 -> 8 -> 15 -> 20 This function adjusts the upcoming path into: 8' -> 15 -> 20 CURR_PATH_NUM is an index into the global paths table. It specifies the path that was just threaded.

References cancel_thread(), jt_path_registry::debug_path(), dump_file, dump_flags, gcc_assert, jt_path_registry::m_paths, MIN, rewire_first_differing_edge(), and TDF_DETAILS.

Referenced by duplicate_thread_path().

◆ allocate_thread_path()

vec< jump_thread_edge * > * jt_path_registry::allocate_thread_path ( )
inherited

◆ cancel_invalid_paths()

bool jt_path_registry::cancel_invalid_paths ( vec< jump_thread_edge * > & path)
privateinherited

◆ debug()

void jt_path_registry::debug ( )
inherited

References debug_path(), i, and m_paths.

◆ debug_path()

void jt_path_registry::debug_path ( FILE * dump_file,
int pathno )
protectedinherited

◆ DISABLE_COPY_AND_ASSIGN()

jt_path_registry::DISABLE_COPY_AND_ASSIGN ( jt_path_registry )
privateinherited

References jt_path_registry().

◆ duplicate_thread_path()

bool back_jt_path_registry::duplicate_thread_path ( edge entry,
edge exit,
basic_block * region,
unsigned n_region,
unsigned current_path_no )
privateinherited
Duplicates a jump-thread path of N_REGION basic blocks. The ENTRY edge is redirected to the duplicate of the region. Remove the last conditional statement in the last basic block in the REGION, and create a single fallthru edge pointing to the same destination as the EXIT edge. CURRENT_PATH_NO is an index into the global paths[] table specifying the jump-thread path. Returns false if it is unable to copy the region, true otherwise.

References add_phi_args_after_copy(), adjust_paths_after_duplication(), profile_probability::always(), bb_in_bbs(), can_copy_bbs_p(), copy_bbs(), basic_block_def::count, count, find_edge(), flush_pending_stmts(), FOR_EACH_EDGE, free(), free_original_copy_tables(), gcc_assert, get_bb_copy(), get_bb_original(), loop::header, i, initialize_original_copy_tables(), profile_count::initialized_p(), make_edge(), mark_loop_for_removal(), NULL, redirect_edge_and_branch(), redirect_edge_and_branch_force(), remove_ctrl_stmt_and_useless_edges(), rescan_loop_exit(), scale_bbs_frequencies_profile_count(), set_loop_copy(), single_succ_edge(), single_succ_p(), split_edge_bb_loc(), basic_block_def::succs, update_bb_profile_for_threading(), and verify_jump_thread().

Referenced by update_cfg().

◆ push_edge()

void jt_path_registry::push_edge ( vec< jump_thread_edge * > * path,
edge e,
jump_thread_edge_type type )
inherited

References m_allocator, and path.

Referenced by back_threader_registry::register_path().

◆ register_jump_thread()

bool jt_path_registry::register_jump_thread ( vec< jump_thread_edge * > * path)
inherited
Register a jump threading opportunity. We queue up all the jump threading opportunities discovered by a pass and update the CFG and SSA form all at once. E is the edge we can thread, E2 is the new target edge, i.e., we are effectively recording that E->dest can be changed to E2->dest after fixing the SSA graph. Return TRUE if PATH was successfully threaded.

References cancel_invalid_paths(), dbg_cnt(), dump_file, dump_flags, dump_jump_thread_path(), gcc_checking_assert, m_paths, path, and TDF_DETAILS.

Referenced by back_threader_registry::register_path().

◆ register_path()

bool back_threader_registry::register_path ( const vec< basic_block > & m_path,
edge taken_edge )
The current path PATH is a vector of blocks forming a jump threading path in reverse order. TAKEN_EDGE is the edge taken from path[0]. Convert the current path into the form used by register_jump_thread and register it. Return TRUE if successful or FALSE otherwise.

References jt_path_registry::allocate_thread_path(), EDGE_COPY_SRC_BLOCK, EDGE_NO_COPY_SRC_BLOCK, find_edge(), gcc_assert, jt_path_registry::push_edge(), and jt_path_registry::register_jump_thread().

◆ rewire_first_differing_edge()

bool back_jt_path_registry::rewire_first_differing_edge ( unsigned path_num,
unsigned edge_num )
privateinherited
Rewire a jump_thread_edge so that the source block is now a threaded source block. PATH_NUM is an index into the global path table PATHS. EDGE_NUM is the jump thread edge number into said path. Returns TRUE if we were able to successfully rewire the edge.

References dump_file, dump_flags, find_edge(), get_bb_copy(), jt_path_registry::m_paths, NULL, path, and TDF_DETAILS.

Referenced by adjust_paths_after_duplication().

◆ thread_through_all_blocks()

bool jt_path_registry::thread_through_all_blocks ( bool peel_loop_headers)
inherited
Thread all paths that have been queued for jump threading, and update the CFG accordingly. It is the caller's responsibility to fix the dominance information and rewrite duplicated SSA_NAMEs back into SSA form. If PEEL_LOOP_HEADERS is false, avoid threading edges through loop headers if it does not simplify the loop. Returns true if one or more edges were threaded.

References cfun, LOOPS_NEED_FIXUP, loops_state_set(), m_num_threaded_edges, m_paths, statistics_counter_event(), and update_cfg().

◆ update_cfg()

bool back_jt_path_registry::update_cfg ( bool peel_loop_headers)
overrideprivatevirtualinherited

Field Documentation

◆ m_allocator

jump_thread_path_allocator jt_path_registry::m_allocator
privateinherited

Referenced by allocate_thread_path(), and push_edge().

◆ m_backedge_threads

bool jt_path_registry::m_backedge_threads
privateinherited

◆ m_num_threaded_edges

unsigned long jt_path_registry::m_num_threaded_edges
protectedinherited

◆ m_paths


The documentation for this class was generated from the following file: