#include <tree-ssa-threadedge.h>

Collaboration diagram for jump_threader:

Public Member Functions
	jump_threader (jt_simplifier , class jt_state )

	~jump_threader ()

void	thread_outgoing_edges (basic_block)

void	remove_jump_threads_including (edge_def *)

bool	thread_through_all_blocks (bool may_peel_loop_headers)

Private Member Functions
tree	simplify_control_stmt_condition (edge, gimple *)

tree	simplify_control_stmt_condition_1 (edge, gimple *, tree op0, tree_code cond_code, tree op1, unsigned limit)

bool	thread_around_empty_blocks (vec< class jump_thread_edge * > *path, edge, bitmap visited)

int	thread_through_normal_block (vec< jump_thread_edge * > *path, edge, bitmap visited)

void	thread_across_edge (edge)

bool	record_temporary_equivalences_from_phis (edge)

gimple *	record_temporary_equivalences_from_stmts_at_dest (edge)

Private Attributes
gcond *	dummy_cond

class fwd_jt_path_registry *	m_registry

jt_simplifier *	m_simplifier

jt_state *	m_state

Constructor & Destructor Documentation

◆ jump_threader()

jump_threader::jump_threader	(	jt_simplifier *	simplifier,
		class jt_state *	state )

References dummy_cond, gcc_assert, ggc_alloc(), gimple_build_cond(), integer_zero_node, m_registry, m_simplifier, m_state, NULL, num_ssa_names, and ssa_name_values.

◆ ~jump_threader()

jump_threader::~jump_threader ( void )

References dummy_cond, ggc_free(), m_registry, and ssa_name_values.

Member Function Documentation

◆ record_temporary_equivalences_from_phis()

bool jump_threader::record_temporary_equivalences_from_phis ( edge e )

private

Record temporary equivalences created by PHIs at the target of the
edge E.

If a PHI which prevents threading is encountered, then return FALSE
indicating we should not thread this edge, else return TRUE.

References ggc_alloc(), gimple_bb(), gimple_phi_result(), gsi_end_p(), gsi_next(), gsi_start_phis(), m_state, gphi_iterator::phi(), PHI_ARG_DEF_FROM_EDGE, jt_state::register_equiv(), SSA_NAME_DEF_STMT, stmt_count, TREE_CODE, and virtual_operand_p().

Referenced by thread_through_normal_block().

◆ record_temporary_equivalences_from_stmts_at_dest()

gimple * jump_threader::record_temporary_equivalences_from_stmts_at_dest ( edge e )

private

Try to simplify each statement in E->dest, ultimately leading to
a simplification of the COND_EXPR at the end of E->dest.

Record unwind information for temporary equivalences onto STACK.

Uses M_SIMPLIFIER to further simplify statements using pass specific
information.

We might consider marking just those statements which ultimately
feed the COND_EXPR.  It's not clear if the overhead of bookkeeping
would be recovered by trying to simplify fewer statements.

If we are able to simplify a statement into the form
SSA_NAME = (SSA_NAME | gimple invariant), then we can record
a context sensitive equivalence which may help us simplify
later statements in E->dest.

References BUILT_IN_NORMAL, DECL_FUNCTION_CODE(), dump_file, estimate_threading_killed_stmts(), fndecl_built_in_p(), ggc_alloc(), gimple_asm_volatile_p(), gimple_assign_lhs(), gimple_call_builtin_p(), gimple_call_fndecl(), gimple_call_internal_p(), gimple_call_internal_unique_p(), gimple_call_lhs(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_stmt(), is_gimple_call(), is_gimple_debug(), m_simplifier, m_state, NULL, NULL_TREE, jt_state::record_ranges_from_stmt(), jt_state::register_equivs_stmt(), stmt_count, and TREE_CODE.

Referenced by thread_through_normal_block().

◆ remove_jump_threads_including()

void jump_threader::remove_jump_threads_including ( edge_def * e )

References m_registry, and fwd_jt_path_registry::remove_jump_threads_including().

◆ simplify_control_stmt_condition()

tree jump_threader::simplify_control_stmt_condition	(	edge	e,
		gimple *	stmt )

private

Simplify the control statement at the end of the block E->dest.

Use SIMPLIFY (a pointer to a callback function) to further simplify
a condition using pass specific information.

Return the simplified condition or NULL if simplification could
not be performed.  When simplifying a GIMPLE_SWITCH, we may return
the CASE_LABEL_EXPR that will be taken.

References gcc_unreachable, ggc_alloc(), ggc_free(), gimple_cond_code(), gimple_cond_lhs(), gimple_cond_rhs(), gimple_copy(), gimple_goto_dest(), gimple_switch_index(), gimple_switch_set_index(), i, INTEGRAL_TYPE_P, is_gimple_min_invariant(), m_simplifier, m_state, NULL, POINTER_TYPE_P, jt_simplifier::simplify(), simplify_control_stmt_condition_1(), SSA_NAME_VALUE, TREE_CODE, and TREE_TYPE.

Referenced by thread_around_empty_blocks(), and thread_through_normal_block().

◆ simplify_control_stmt_condition_1()

tree jump_threader::simplify_control_stmt_condition_1	(	edge	e,
		gimple *	stmt,
		tree	op0,
		tree_code	cond_code,
		tree	op1,
		unsigned	limit )

private

Recursive helper for simplify_control_stmt_condition.

References boolean_false_node, boolean_true_node, boolean_type_node, CONVERT_EXPR_P, dummy_cond, fold_binary, fold_defer_overflow_warnings(), fold_undefer_overflow_warnings(), ggc_alloc(), gimple_assign_rhs1(), gimple_assign_rhs2(), gimple_assign_rhs_code(), gimple_cond_set_code(), gimple_cond_set_lhs(), gimple_cond_set_rhs(), integer_nonzerop(), integer_zerop(), invert_tree_comparison(), is_gimple_min_invariant(), m_simplifier, m_state, NULL_TREE, jt_simplifier::simplify(), simplify_control_stmt_condition_1(), SSA_NAME_DEF_STMT, swap_tree_comparison(), tcc_comparison, TREE_CODE, TREE_CODE_CLASS, TREE_OPERAND, tree_swap_operands_p(), TREE_TYPE, TYPE_PRECISION, and WARN_STRICT_OVERFLOW_CONDITIONAL.

Referenced by simplify_control_stmt_condition(), and simplify_control_stmt_condition_1().

◆ thread_across_edge()

void jump_threader::thread_across_edge ( edge e )

private

We are exiting E->src, see if E->dest ends with a conditional jump
which has a known value when reached via E.  If so, thread the
edge.

References jt_path_registry::allocate_thread_path(), bitmap_clear(), bitmap_set_bit, EDGE_COMPLEX, EDGE_COPY_SRC_JOINER_BLOCK, edge_forwards_cmp_to_conditional_jump_through_empty_bb_p(), EDGE_START_JUMP_THREAD, FOR_EACH_EDGE, gcc_checking_assert, ggc_alloc(), m_registry, m_state, jt_state::pop(), propagate_threaded_block_debug_into(), jt_state::push(), jt_path_registry::push_edge(), jt_path_registry::register_jump_thread(), stmt_count, thread_around_empty_blocks(), thread_through_normal_block(), and visited.

Referenced by thread_outgoing_edges().

◆ thread_around_empty_blocks()

bool jump_threader::thread_around_empty_blocks	(	vec< class jump_thread_edge * > *	path,
		edge	taken_edge,
		bitmap	visited )

private

See if TAKEN_EDGE->dest is a threadable block with no side effecs (ie, it
need not be duplicated as part of the CFG/SSA updating process).

If it is threadable, add it to PATH and VISITED and recurse, ultimately
returning TRUE from the toplevel call.   Otherwise do nothing and
return false.

References jt_state::append_path(), bitmap_bit_p, bitmap_set_bit, CASE_LABEL, cfun, EDGE_NO_COPY_SRC_BLOCK, find_edge(), find_taken_edge(), ggc_alloc(), gsi_end_p(), gsi_start_nondebug_bb(), gsi_stmt(), has_phis_p(), is_gimple_min_invariant(), label_to_block(), m_registry, m_state, NULL_TREE, jt_path_registry::push_edge(), simplify_control_stmt_condition(), single_succ_edge(), single_succ_p(), thread_around_empty_blocks(), TREE_CODE, and visited.

Referenced by thread_across_edge(), thread_around_empty_blocks(), and thread_through_normal_block().

◆ thread_outgoing_edges()

void jump_threader::thread_outgoing_edges ( basic_block bb )

Examine the outgoing edges from BB and conditionally
try to thread them.

References EDGE_COMPLEX, EDGE_COUNT, EDGE_SUCC, extract_true_false_edges_from_block(), ggc_alloc(), gsi_last_bb(), potentially_threadable_block(), single_succ_edge(), single_succ_to_potentially_threadable_block(), basic_block_def::succs, and thread_across_edge().

◆ thread_through_all_blocks()

bool jump_threader::thread_through_all_blocks ( bool may_peel_loop_headers )

References ggc_alloc(), m_registry, and jt_path_registry::thread_through_all_blocks().

◆ thread_through_normal_block()

int jump_threader::thread_through_normal_block	(	vec< jump_thread_edge * > *	path,
		edge	e,
		bitmap	visited )

private

We are exiting E->src, see if E->dest ends with a conditional
jump which has a known value when reached via E.

E->dest can have arbitrary side effects which, if threading is
successful, will be maintained.

Special care is necessary if E is a back edge in the CFG as we
may have already recorded equivalences for E->dest into our
various tables, including the result of the conditional at
the end of E->dest.  Threading opportunities are severely
limited in that case to avoid short-circuiting the loop
incorrectly.

Positive return value is success.  Zero return value is failure, but
the block can still be duplicated as a joiner in a jump thread path,
negative indicates the block should not be duplicated and thus is not
suitable for a joiner in a jump threading path.

References jt_state::append_path(), bitmap_bit_p, bitmap_set_bit, CASE_LABEL, cfun, EDGE_COPY_SRC_BLOCK, EDGE_START_JUMP_THREAD, empty_block_with_phis_p(), find_edge(), find_taken_edge(), ggc_alloc(), basic_block_def::index, is_gimple_min_invariant(), label_to_block(), m_registry, m_state, NULL, jt_path_registry::push_edge(), record_temporary_equivalences_from_phis(), record_temporary_equivalences_from_stmts_at_dest(), jt_state::register_equivs_edge(), simplify_control_stmt_condition(), thread_around_empty_blocks(), TREE_CODE, and visited.

Referenced by thread_across_edge().

Field Documentation

◆ dummy_cond

gcond* jump_threader::dummy_cond

private

Referenced by jump_threader(), simplify_control_stmt_condition_1(), and ~jump_threader().

◆ m_registry

class fwd_jt_path_registry* jump_threader::m_registry

private

Referenced by jump_threader(), remove_jump_threads_including(), thread_across_edge(), thread_around_empty_blocks(), thread_through_all_blocks(), thread_through_normal_block(), and ~jump_threader().

◆ m_simplifier

jt_simplifier* jump_threader::m_simplifier

private

Referenced by jump_threader(), record_temporary_equivalences_from_stmts_at_dest(), simplify_control_stmt_condition(), and simplify_control_stmt_condition_1().

◆ m_state

jt_state* jump_threader::m_state

private

Referenced by jump_threader(), record_temporary_equivalences_from_phis(), record_temporary_equivalences_from_stmts_at_dest(), simplify_control_stmt_condition(), simplify_control_stmt_condition_1(), thread_across_edge(), thread_around_empty_blocks(), and thread_through_normal_block().

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

Public Member Functions

Private Member Functions

Private Attributes

Constructor & Destructor Documentation

◆ jump_threader()

◆ ~jump_threader()

Member Function Documentation

◆ record_temporary_equivalences_from_phis()

◆ record_temporary_equivalences_from_stmts_at_dest()

◆ remove_jump_threads_including()

◆ simplify_control_stmt_condition()

◆ simplify_control_stmt_condition_1()

◆ thread_across_edge()

◆ thread_around_empty_blocks()

◆ thread_outgoing_edges()

◆ thread_through_all_blocks()

◆ thread_through_normal_block()

Field Documentation

◆ dummy_cond

◆ m_registry

◆ m_simplifier

◆ m_state