ipa-split.c File Reference

Data Structures
struct	bb_info
struct	split_point
struct	stack_entry

Functions
static tree	find_retval (basic_block return_bb)
static bool	test_nonssa_use ()
static void	dump_split_point ()
static bool	verify_non_ssa_vars (struct split_point *current, bitmap non_ssa_vars, basic_block return_bb)
static void	check_forbidden_calls ()
static bool	dominated_by_forbidden ()
static void	consider_split (struct split_point *current, bitmap non_ssa_vars, basic_block return_bb)
static basic_block	find_return_bb ()
static tree	find_retval ()
static bool	mark_nonssa_use ()
static bool	visit_bb (basic_block bb, basic_block return_bb, bitmap set_ssa_names, bitmap used_ssa_names, bitmap non_ssa_vars)
static void	find_split_points ()
static void	split_function ()
static unsigned int	execute_split_functions ()
static bool	gate_split_functions ()
gimple_opt_pass *	make_pass_split_functions ()
static bool	gate_feedback_split_functions ()
static unsigned int	execute_feedback_split_functions ()
gimple_opt_pass *	make_pass_feedback_split_functions ()

Variables
static vec< bb_info >	bb_info_vec
struct split_point	best_split_point
static bitmap	forbidden_dominators

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Function Documentation

static void check_forbidden_calls ( )

static

If STMT is a call, check the callee against a list of forbidden
   predicate functions.  If a match is found, look for uses of the
   call result in condition statements that compare against zero.
   For each such use, find the block targeted by the condition
   statement for the nonzero result, and set the bit for this block
   in the forbidden dominators bitmap.  The purpose of this is to avoid
   selecting a split point where we are likely to lose the chance
   to optimize away an unused function call.   

References bitmap_set_bit(), edge_def::dest, extract_true_false_edges_from_block(), gimple_bb(), gimple_call_builtin_p(), gimple_call_lhs(), gimple_cond_code(), gimple_cond_rhs(), basic_block_def::index, and integer_zerop().

Referenced by execute_split_functions().

static void consider_split ( struct split_point *  current, bitmap  non_ssa_vars, basic_block  return_bb  )

static

We found an split_point CURRENT.  NON_SSA_VARS is bitmap of all non ssa
   variables used and RETURN_BB is return basic block.
   See if we can split function here.   

References best_split_point, bitmap_bit_p(), bitmap_copy(), bitmap_count_bits(), bitmap_empty_p(), eni_weights_d::call_cost, cfun, current_function_decl, dominated_by_forbidden(), dump_file, dump_flags, dump_split_point(), eni_size_weights, split_point::entry_bb, estimate_move_cost(), find_retval(), edge_def::flags, frequency, basic_block_def::frequency, gimple_bb(), gimple_phi_arg_def(), gimple_phi_arg_edge(), gimple_phi_num_args(), gimple_phi_result(), gsi_end_p(), gsi_next(), gsi_start_phis(), gsi_stmt(), split_point::header_size, basic_block_def::index, is_gimple_min_invariant(), is_gimple_reg(), basic_block_def::preds, PROFILE_READ, split_point::split_bbs, split_point::split_part_set_retval, split_point::split_size, edge_def::src, ssa_default_def(), split_point::ssa_names_to_pass, verify_non_ssa_vars(), and virtual_operand_p().

Referenced by find_split_points().

static bool dominated_by_forbidden ( )

static

If BB is dominated by any block in the forbidden dominators set,
   return TRUE; else FALSE.   

References CDI_DOMINATORS, and dominated_by_p().

Referenced by consider_split().

static void dump_split_point ( )

static

Dump split point CURRENT.   

References dump_bitmap(), split_point::entry_bb, split_point::header_size, split_point::header_time, basic_block_def::index, split_point::split_bbs, split_point::split_size, split_point::split_time, and split_point::ssa_names_to_pass.

Referenced by consider_split(), and split_function().

static unsigned int execute_feedback_split_functions ( )

static

Execute function splitting pass.   

References execute_split_functions().

static unsigned int execute_split_functions ( )

static

Execute function splitting pass.   

References symtab_node_base::address_taken, best_split_point, calculate_dominance_info(), cgraph_node::callers, CDI_DOMINATORS, cgraph_get_node(), check_forbidden_calls(), compute_call_stmt_bb_frequency(), current_function_decl, symtab_node_base::decl, dump_file, dump_flags, eni_size_weights, eni_time_weights, estimate_num_insns(), symtab_node_base::externally_visible, find_split_points(), flags_from_decl_or_type(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_stmt(), basic_block_def::index, inline_summary::inlinable, inline_edge_summary_vec, inline_summary(), mark_dfs_back_edges(), memset(), cgraph_edge::next_caller, overall_size, print_gimple_stmt(), PROFILE_READ, split_point::split_bbs, split_function(), split_point::ssa_names_to_pass, cgraph_node::symbol, and tree_versionable_function_p().

Referenced by execute_feedback_split_functions().

static basic_block find_return_bb ( )

static

Return basic block containing RETURN statement.  We allow basic blocks
   of the form:
   <retval> = tmp_var;
   return <retval>
   but return_bb can not be more complex than this.
   If nothing is found, return EXIT_BLOCK_PTR.

   When there are multiple RETURN statement, chose one with return value,
   since that one is more likely shared by multiple code paths.

   Return BB is special, because for function splitting it is the only
   basic block that is duplicated in between header and split part of the
   function.

   TODO: We might support multiple return blocks.   

References auto_var_in_fn_p(), current_function_decl, gimple_assign_lhs(), gimple_assign_rhs1(), gimple_assign_single_p(), gimple_clobber_p(), gimple_return_retval(), gsi_end_p(), gsi_last_bb(), gsi_prev(), gsi_stmt(), is_gimple_debug(), is_gimple_min_invariant(), single_pred_edge(), single_pred_p(), and edge_def::src.

Referenced by find_split_points(), and split_function().

static tree find_retval ( basic_block  return_bb )

static

Referenced by consider_split(), and split_function().

static tree find_retval ( )

static

Given return basic block RETURN_BB, see where return value is really
   stored.   

References gimple_assign_rhs1(), gimple_clobber_p(), gimple_return_retval(), gsi_end_p(), gsi_next(), gsi_start_bb(), and gsi_stmt().

static void find_split_points ( )

static

Find all articulations and call consider_split on them.
   OVERALL_TIME and OVERALL_SIZE is time and size of the function.

   We perform basic algorithm for finding an articulation in a graph
   created from CFG by considering it to be an unoriented graph.

   The articulation is discovered via DFS walk. We collect earliest
   basic block on stack that is reachable via backward edge.  Articulation
   is any basic block such that there is no backward edge bypassing it.
   To reduce stack usage we maintain heap allocated stack in STACK vector.
   AUX pointer of BB is set to index it appears in the stack or -1 once
   it is visited and popped off the stack.

   The algorithm finds articulation after visiting the whole component
   reachable by it.  This makes it convenient to collect information about
   the component used by consider_split.   

References basic_block_def::aux, stack_entry::bb, stack_entry::bbs_visited, bitmap_and_compl(), bitmap_ior_into(), bitmap_set_bit(), stack_entry::can_split, consider_split(), edge_def::dest, dump_file, dump_flags, stack_entry::earliest, stack_entry::edge_num, split_point::entry_bb, find_return_bb(), first, split_point::header_size, split_point::header_time, basic_block_def::index, stack_entry::non_ssa_vars, overall_size, stack_entry::overall_size, stack_entry::overall_time, basic_block_def::preds, stack_entry::set_ssa_names, split_point::split_bbs, split_point::split_size, split_point::split_time, edge_def::src, split_point::ssa_names_to_pass, stack, basic_block_def::succs, stack_entry::used_ssa_names, visit_bb(), and vNULL.

Referenced by execute_split_functions().

static bool gate_feedback_split_functions ( )

static

Gate feedback driven function splitting pass.
   We don't need to split when profiling at all, we are producing
   lousy code anyway.   

static bool gate_split_functions ( )

static

Gate function splitting pass.  When doing profile feedback, we want
   to execute the pass after profiling is read.  So disable one in 
   early optimization.   

gimple_opt_pass* make_pass_feedback_split_functions

(

)

gimple_opt_pass* make_pass_split_functions

(

)

static bool mark_nonssa_use ( )

static

Callback for walk_stmt_load_store_addr_ops.  If T is non-SSA automatic
   variable, mark it as used in bitmap passed via DATA.
   Return true when access to T prevents splitting the function.   

References auto_var_in_fn_p(), bitmap_bit_p(), bitmap_set_bit(), current_function_decl, dump_file, dump_flags, get_base_address(), and is_gimple_reg().

Referenced by visit_bb().

static void split_function ( )

static

Split function at SPLIT_POINT.   

References add_bb_to_loop(), add_phi_arg(), aggregate_value_p(), bitmap_bit_p(), bitmap_set_bit(), cgraph_local_info::can_change_signature, CDI_DOMINATORS, CDI_POST_DOMINATORS, cfun, cgraph_function_versioning(), cgraph_get_node(), cgraph_node_remove_callees(), compute_inline_parameters(), copy_ssa_name(), edge_def::count, basic_block_def::count, create_basic_block(), create_tmp_reg(), current_function_decl, symtab_node_base::decl, decl_debug_args_insert(), dump_file, dump_flags, dump_function_to_file(), dump_split_point(), split_point::entry_bb, find_return_bb(), find_retval(), force_gimple_operand_gsi(), free_dominance_info(), basic_block_def::frequency, get_or_create_ssa_default_def(), gimple_assign_set_rhs1(), gimple_build_assign_with_ops(), gimple_build_call_vec(), gimple_build_return(), gimple_call_set_lhs(), gimple_call_set_return_slot_opt(), gimple_clobber_p(), gimple_phi_result(), gimple_return_set_retval(), gimple_set_block(), gimple_set_vuse(), gimple_vdef(), gimple_vuse(), gsi_after_labels(), GSI_CONTINUE_LINKING, gsi_end_p(), gsi_insert_after(), gsi_insert_before(), gsi_last_bb(), GSI_NEW_STMT, gsi_next(), GSI_SAME_STMT, gsi_start_bb(), gsi_start_phis(), gsi_stmt(), basic_block_def::index, ipa_remove_all_references(), is_gimple_reg(), is_gimple_reg_type(), is_gimple_val(), last_stmt(), cgraph_node::local, make_edge(), make_ssa_name(), mark_virtual_phi_result_for_renaming(), NOT_BUILT_IN, pop_cfun(), basic_block_def::preds, edge_def::probability, push_cfun(), rebuild_cgraph_edges(), redirect_edge_and_branch(), symtab_node_base::ref_list, remove_edge(), remove_phi_node(), single_succ(), split_point::split_bbs, split_block(), split_point::split_part_set_retval, edge_def::src, ssa_default_def(), split_point::ssa_names_to_pass, cgraph_node::symbol, unshare_expr(), update_stmt(), useless_type_conversion_p(), vec_safe_length(), vec_safe_push(), virtual_operand_p(), and vNULL.

Referenced by execute_split_functions().

static bool test_nonssa_use ( )

static

Callback for walk_stmt_load_store_addr_ops.  If T is non-SSA automatic
   variable, check it if it is present in bitmap passed via DATA.   

References auto_var_in_fn_p(), bitmap_bit_p(), current_function_decl, get_base_address(), and is_gimple_reg().

Referenced by verify_non_ssa_vars().

static bool verify_non_ssa_vars ( struct split_point *  current, bitmap  non_ssa_vars, basic_block  return_bb  )

static

Look for all BBs in header that might lead to the split part and verify
   that they are not defining any non-SSA var used by the split part.
   Parameters are the same as for consider_split.   

References bitmap_bit_p(), bitmap_set_bit(), edge_def::dest, edge_def::dest_idx, split_point::entry_bb, gimple_label_label(), gimple_phi_arg_def(), gimple_phi_result(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_start_phis(), gsi_stmt(), basic_block_def::index, is_gimple_debug(), basic_block_def::preds, split_point::split_bbs, edge_def::src, basic_block_def::succs, test_nonssa_use(), virtual_operand_p(), vNULL, walk_stmt_load_store_addr_ops(), and worklist.

Referenced by consider_split().

static bool visit_bb ( basic_block  bb, basic_block  return_bb, bitmap  set_ssa_names, bitmap  used_ssa_names, bitmap  non_ssa_vars  )

static

Compute local properties of basic block BB we collect when looking for
   split points.  We look for ssa defs and store them in SET_SSA_NAMES,
   for ssa uses and store them in USED_SSA_NAMES and for any non-SSA automatic
   vars stored in NON_SSA_VARS.

   When BB has edge to RETURN_BB, collect uses in RETURN_BB too.  

   Return false when BB contains something that prevents it from being put into
   split function.   

References bitmap_set_bit(), BUILT_IN_NORMAL, edge_def::dest, edge_def::dest_idx, dump_file, dump_flags, gimple_call_fndecl(), gimple_clobber_p(), gimple_phi_arg_def(), gimple_phi_num_args(), gimple_phi_result(), gsi_end_p(), gsi_next(), gsi_start_bb(), gsi_start_phis(), gsi_stmt(), is_gimple_debug(), mark_nonssa_use(), basic_block_def::succs, virtual_operand_p(), and walk_stmt_load_store_addr_ops().

Referenced by find_split_points().

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Variable Documentation

vec<bb_info> bb_info_vec

static

struct split_point best_split_point

Best split point found.   

Referenced by consider_split(), and execute_split_functions().

bitmap forbidden_dominators

static

Set of basic blocks that are not allowed to dominate a split point.