GCC Middle and Back End API Reference
back_jt_path_registry Class Reference

#include <tree-ssa-threadupdate.h>

Inheritance diagram for back_jt_path_registry:
Collaboration diagram for back_jt_path_registry:

Public Member Functions

 back_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 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

Constructor & Destructor Documentation

◆ back_jt_path_registry()

back_jt_path_registry::back_jt_path_registry ( )

Member Function Documentation

◆ adjust_paths_after_duplication()

void back_jt_path_registry::adjust_paths_after_duplication ( unsigned curr_path_num)
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()

◆ cancel_invalid_paths()

◆ debug()

void jt_path_registry::debug ( )

◆ debug_path()

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


jt_path_registry::DISABLE_COPY_AND_ASSIGN ( 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 )
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()

◆ register_jump_thread()

bool jt_path_registry::register_jump_thread ( vec< jump_thread_edge * > * path)
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 jt_path_registry::cancel_invalid_paths(), dbg_cnt(), dump_file, dump_flags, dump_jump_thread_path(), gcc_checking_assert, jt_path_registry::m_paths, and TDF_DETAILS.

Referenced by back_threader_registry::register_path(), and jump_threader::thread_across_edge().

◆ rewire_first_differing_edge()

bool back_jt_path_registry::rewire_first_differing_edge ( unsigned path_num,
unsigned edge_num )
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, 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)
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(), jt_path_registry::m_num_threaded_edges, jt_path_registry::m_paths, statistics_counter_event(), and jt_path_registry::update_cfg().

Referenced by back_threader::thread_blocks(), and jump_threader::thread_through_all_blocks().

◆ update_cfg()

bool back_jt_path_registry::update_cfg ( bool peel_loop_headers)

Field Documentation

◆ m_allocator

jump_thread_path_allocator jt_path_registry::m_allocator

◆ m_backedge_threads

bool jt_path_registry::m_backedge_threads

◆ m_num_threaded_edges

unsigned long jt_path_registry::m_num_threaded_edges

◆ m_paths

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