dom_opt_dom_walker Class Reference

Inheritance diagram for dom_opt_dom_walker:

Collaboration diagram for dom_opt_dom_walker:

Public Types
enum	reachability { ALL_BLOCKS , REACHABLE_BLOCKS , REACHABLE_BLOCKS_PRESERVING_FLAGS }

Public Member Functions
	dom_opt_dom_walker (cdi_direction direction, jump_threader *threader, dom_jt_state *state, gimple_ranger *ranger, const_and_copies *const_and_copies, avail_exprs_stack *avail_exprs_stack)
edge	before_dom_children (basic_block) final override
void	after_dom_children (basic_block) final override
void	walk (basic_block)

Static Public Attributes
static const edge	STOP = (edge)-1

Private Member Functions
edge	optimize_stmt (basic_block, gimple_stmt_iterator *, bool *)
void	set_global_ranges_from_unreachable_edges (basic_block)
void	test_for_singularity (gimple *, avail_exprs_stack *)
edge	fold_cond (gcond *cond)
bool	bb_reachable (struct function *, basic_block)
void	propagate_unreachable_to_edges (basic_block, FILE *, dump_flags_t)

Private Attributes
class const_and_copies *	m_const_and_copies
class avail_exprs_stack *	m_avail_exprs_stack
gcond *	m_dummy_cond
jump_threader *	m_threader
gimple_ranger *	m_ranger
dom_jt_state *	m_state
enum cdi_direction	m_dom_direction: 2
enum reachability	m_reachability: 2
bool	m_user_bb_to_rpo
basic_block	m_unreachable_dom
int *	m_bb_to_rpo

Member Enumeration Documentation

reachability

enum dom_walker::reachability

inherited

Enumerator
ALL_BLOCKS
REACHABLE_BLOCKS
REACHABLE_BLOCKS_PRESERVING_FLAGS

Constructor & Destructor Documentation

dom_opt_dom_walker()

dom_opt_dom_walker::dom_opt_dom_walker ( cdi_direction direction, jump_threader * threader, dom_jt_state * state, gimple_ranger * ranger, const_and_copies * const_and_copies, avail_exprs_stack * avail_exprs_stack )

inline

References gimple_build_cond(), integer_zero_node, m_ranger, NULL, and ranger.

Member Function Documentation

after_dom_children()

void dom_opt_dom_walker::after_dom_children ( basic_block bb )

finaloverridevirtual

We have finished processing the dominator children of BB, perform
any finalization actions in preparation for leaving this node in
the dominator tree.   

Reimplemented from dom_walker.

References bitmap_clear_bit(), and basic_block_def::index.

bb_reachable()

bool dom_walker::bb_reachable ( struct function * fun, basic_block bb )

privateinherited

Return TRUE if BB is reachable, false otherwise.   

References dom_walker::ALL_BLOCKS, CDI_DOMINATORS, dominated_by_p(), ENTRY_BLOCK_PTR_FOR_FN, FOR_EACH_EDGE, dom_walker::m_reachability, dom_walker::m_unreachable_dom, and basic_block_def::preds.

Referenced by dom_walker::walk().

before_dom_children()

edge dom_opt_dom_walker::before_dom_children ( basic_block bb )

finaloverridevirtual

Reimplemented from dom_walker.

References bitmap_set_bit, cprop_into_successor_phis(), dbg_cnt(), dump_file, dump_flags, eliminate_redundant_computations(), gcc_checking_assert, gimple_set_visited(), gimple_visited_p(), gsi_end_p(), gsi_last_bb(), gsi_next(), gsi_prev(), gsi_start_bb(), gsi_start_phis(), gsi_stmt(), basic_block_def::index, NULL, record_edge_info(), record_equivalences_from_incoming_edge(), record_equivalences_from_phis(), and TDF_DETAILS.

fold_cond()

edge dom_opt_dom_walker::fold_cond ( gcond * cond )

private

If possible, rewrite the conditional as TRUE or FALSE, and return
the taken edge.  Otherwise, return NULL.   

References boolean_false_node, boolean_true_node, find_taken_edge(), gimple_bb(), gimple_cond_false_p(), gimple_cond_true_p(), m_ranger, and NULL.

optimize_stmt()

edge dom_opt_dom_walker::optimize_stmt ( basic_block bb, gimple_stmt_iterator * si, bool * removed_p )

private

Optimize the statement in block BB pointed to by iterator SI.

We try to perform some simplistic global redundancy elimination and
constant propagation:

1- To detect global redundancy, we keep track of expressions that have
   been computed in this block and its dominators.  If we find that the
   same expression is computed more than once, we eliminate repeated
   computations by using the target of the first one.

2- Constant values and copy assignments.  This is used to do very
   simplistic constant and copy propagation.  When a constant or copy
   assignment is found, we map the value on the RHS of the assignment to
   the variable in the LHS in the CONST_AND_COPIES table.

3- Very simple redundant store elimination is performed.

4- We can simplify a condition to a constant or from a relational
   condition to an equality condition.   

References as_a(), bitmap_set_bit, boolean_type_node, cfg_altered, cprop_into_stmt(), dom_valueize(), dump_file, dump_flags, dyn_cast(), eliminate_redundant_computations(), expr_hash_elt::expr(), EXPR_SINGLE, find_taken_edge(), fndecl_built_in_p(), fold_binary_loc(), fold_convert, fold_stmt(), gcc_unreachable, gimple_assign_lhs(), gimple_assign_rhs1(), gimple_assign_single_p(), gimple_bb(), gimple_build_assign(), gimple_call_fndecl(), gimple_call_lhs(), gimple_call_noreturn_p(), gimple_cond_code(), gimple_cond_lhs(), gimple_cond_make_false(), gimple_cond_make_true(), gimple_cond_rhs(), gimple_cond_set_lhs(), gimple_goto_dest(), gimple_has_side_effects(), gimple_location(), gimple_modified_p(), gimple_set_modified(), gimple_set_vuse(), gimple_switch_index(), gimple_vuse(), gsi_remove(), gsi_stmt(), basic_block_def::index, integer_onep(), integer_zero_node, integer_zerop(), is_gimple_assign(), is_gimple_call(), hashable_expr::kind, m_ranger, maybe_clean_or_replace_eh_stmt(), need_eh_cleanup, need_noreturn_fixup, NULL, NULL_TREE, opt_stats_d::num_stmts, operand_equal_p(), hashable_expr::ops, opt_stats, print_gimple_stmt(), propagate_tree_value_into_stmt(), recompute_tree_invariant_for_addr_expr(), record_equivalences_from_stmt(), reduce_vector_comparison_to_scalar_comparison(), refs_same_for_tbaa_p(), release_defs(), hashable_expr::rhs, si, hashable_expr::single, SSA_NAME_DEF_STMT, ssa_name_has_boolean_range(), TDF_DETAILS, TDF_SLIM, test_for_singularity(), TREE_CODE, TREE_TYPE, unlink_stmt_vdef(), update_stmt(), and update_stmt_if_modified().

propagate_unreachable_to_edges()

void dom_walker::propagate_unreachable_to_edges ( basic_block bb, FILE * dump_file, dump_flags_t dump_flags )

privateinherited

BB has been determined to be unreachable.  Propagate that property
to incoming and outgoing edges of BB as appropriate.   

References CDI_DOMINATORS, dominated_by_p(), dump_file, dump_flags, FOR_EACH_EDGE, basic_block_def::index, dom_walker::m_unreachable_dom, basic_block_def::preds, basic_block_def::succs, and TDF_DETAILS.

Referenced by dom_walker::walk().

set_global_ranges_from_unreachable_edges()

void dom_opt_dom_walker::set_global_ranges_from_unreachable_edges ( basic_block bb )

private

Set global ranges that can be determined from the C->M edge:

  <bb C>:
  ...
  if (something)
    goto <bb N>;
  else
    goto <bb M>;
  <bb N>:
  __builtin_unreachable ();
  <bb M>:

References all_uses_feed_or_dominated_by_stmt(), assert_unreachable_fallthru_edge_p(), FOR_EACH_GORI_EXPORT_NAME, gimple_bb(), range_query::gori_ssa(), gsi_last_bb(), m_ranger, maybe_set_nonzero_bits(), r, gimple_ranger::range_on_edge(), set_range_info(), single_pred_edge_ignoring_loop_edges(), SSA_NAME_DEF_STMT, SSA_NAME_IS_DEFAULT_DEF, and TREE_TYPE.

test_for_singularity()

void dom_opt_dom_walker::test_for_singularity ( gimple * stmt, avail_exprs_stack * avail_exprs_stack )

private

If STMT contains a relational test, try to convert it into an
equality test if there is only a single value which can ever
make the test true.

For example, if the expression hash table contains:

 TRUE = (i <= 1)

And we have a test within statement of i >= 1, then we can safely
rewrite the test as i == 1 since there only a single value where
the test is true.

This is similar to code in VRP.   

References as_a(), build_int_cst(), fold_build2, gimple_assign_rhs1(), gimple_assign_rhs2(), gimple_assign_rhs_code(), gimple_assign_set_rhs2(), gimple_assign_set_rhs_code(), gimple_cond_code(), gimple_cond_lhs(), gimple_cond_rhs(), gimple_cond_set_code(), gimple_cond_set_lhs(), gimple_cond_set_rhs(), gimple_set_modified(), integer_onep(), is_gimple_assign(), avail_exprs_stack::lookup_avail_expr(), TREE_CODE, and TREE_TYPE.

walk()

void dom_walker::walk ( basic_block bb )

inherited

Recursively walk the dominator tree.
BB is the basic block we are currently visiting.   

References dom_walker::after_dom_children(), dom_walker::bb_reachable(), dom_walker::before_dom_children(), CDI_DOMINATORS, cfun, dump_file, dump_flags, EDGE_COUNT, ENTRY_BLOCK_PTR_FOR_FN, EXIT_BLOCK_PTR_FOR_FN, first_dom_son(), FOR_EACH_EDGE, free(), i, last_basic_block_for_fn, dom_walker::m_bb_to_rpo, dom_walker::m_dom_direction, dom_walker::m_reachability, dom_walker::m_unreachable_dom, dom_walker::m_user_bb_to_rpo, n_basic_blocks_for_fn, next_dom_son(), NULL, pre_and_rev_post_order_compute(), basic_block_def::preds, dom_walker::propagate_unreachable_to_edges(), dom_walker::REACHABLE_BLOCKS, set_all_edges_as_executable(), sort_bbs_postorder(), dom_walker::STOP, basic_block_def::succs, and worklist.

Referenced by array_bounds_checker::check(), eliminate_with_rpo_vn(), find_comparisons(), get_non_trapping(), ipa_analyze_node(), ipcp_transform_function(), rewrite_blocks(), and substitute_and_fold_engine::substitute_and_fold().

Field Documentation

m_avail_exprs_stack

class avail_exprs_stack* dom_opt_dom_walker::m_avail_exprs_stack

private

m_bb_to_rpo

int* dom_walker::m_bb_to_rpo

privateinherited

Referenced by dom_walker::walk(), and dom_walker::~dom_walker().

m_const_and_copies

class const_and_copies* dom_opt_dom_walker::m_const_and_copies

private

m_dom_direction

enum cdi_direction dom_walker::m_dom_direction

privateinherited

Referenced by dom_walker::walk().

m_dummy_cond

gcond* dom_opt_dom_walker::m_dummy_cond

private

m_ranger

gimple_ranger* dom_opt_dom_walker::m_ranger

private

m_reachability

enum reachability dom_walker::m_reachability

privateinherited

Referenced by dom_walker::bb_reachable(), and dom_walker::walk().

m_state

dom_jt_state* dom_opt_dom_walker::m_state

private

m_threader

jump_threader* dom_opt_dom_walker::m_threader

private

m_unreachable_dom

basic_block dom_walker::m_unreachable_dom

privateinherited

Referenced by dom_walker::bb_reachable(), dom_walker::propagate_unreachable_to_edges(), and dom_walker::walk().

m_user_bb_to_rpo

bool dom_walker::m_user_bb_to_rpo

privateinherited

Referenced by dom_walker::walk(), and dom_walker::~dom_walker().

STOP

const edge dom_walker::STOP = (edge)-1

staticinherited

Referenced by rewrite_update_dom_walker::before_dom_children(), and dom_walker::walk().

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

• tree-ssa-dom.cc