diff options
Diffstat (limited to 'gcc/tree-into-ssa.c')
| -rw-r--r-- | gcc/tree-into-ssa.c | 141 |
1 files changed, 0 insertions, 141 deletions
diff --git a/gcc/tree-into-ssa.c b/gcc/tree-into-ssa.c index 1130038..335d9c0 100644 --- a/gcc/tree-into-ssa.c +++ b/gcc/tree-into-ssa.c @@ -140,21 +140,6 @@ static htab_t repl_tbl; NULL if they need to be initialized by register_new_name_mapping. */ static struct function *update_ssa_initialized_fn = NULL; -/* Statistics kept by update_ssa to use in the virtual mapping - heuristic. If the number of virtual mappings is beyond certain - threshold, the updater will switch from using the mappings into - renaming the virtual symbols from scratch. In some cases, the - large number of name mappings for virtual names causes significant - slowdowns in the PHI insertion code. */ -struct update_ssa_stats_d -{ - unsigned num_virtual_mappings; - unsigned num_total_mappings; - bitmap virtual_symbols; - unsigned num_virtual_symbols; -}; -static struct update_ssa_stats_d update_ssa_stats; - /* Global data to attach to the main dominator walk structure. */ struct mark_def_sites_global_data { @@ -662,26 +647,6 @@ add_new_name_mapping (tree new_tree, tree old) /* OLD and NEW_TREE must be different SSA names for the same symbol. */ gcc_assert (new_tree != old && SSA_NAME_VAR (new_tree) == SSA_NAME_VAR (old)); - /* If this mapping is for virtual names, we will need to update - virtual operands. If this is a mapping for .MEM, then we gather - the symbols associated with each name. */ - if (!is_gimple_reg (new_tree)) - { - tree sym; - - update_ssa_stats.num_virtual_mappings++; - update_ssa_stats.num_virtual_symbols++; - - /* Keep counts of virtual mappings and symbols to use in the - virtual mapping heuristic. If we have large numbers of - virtual mappings for a relatively low number of symbols, it - will make more sense to rename the symbols from scratch. - Otherwise, the insertion of PHI nodes for each of the old - names in these mappings will be very slow. */ - sym = SSA_NAME_VAR (new_tree); - bitmap_set_bit (update_ssa_stats.virtual_symbols, DECL_UID (sym)); - } - /* We may need to grow NEW_SSA_NAMES and OLD_SSA_NAMES because our caller may have created new names since the set was created. */ if (new_ssa_names->n_bits <= num_ssa_names - 1) @@ -704,9 +669,6 @@ add_new_name_mapping (tree new_tree, tree old) SET_BIT (new_ssa_names, SSA_NAME_VERSION (new_tree)); SET_BIT (old_ssa_names, SSA_NAME_VERSION (old)); - /* Update mapping counter to use in the virtual mapping heuristic. */ - update_ssa_stats.num_total_mappings++; - timevar_pop (TV_TREE_SSA_INCREMENTAL); } @@ -2827,18 +2789,6 @@ dump_update_ssa (FILE *file) EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) dump_names_replaced_by (file, ssa_name (i)); - - fprintf (file, "\n"); - fprintf (file, "Number of virtual NEW -> OLD mappings: %7u\n", - update_ssa_stats.num_virtual_mappings); - fprintf (file, "Number of real NEW -> OLD mappings: %7u\n", - update_ssa_stats.num_total_mappings - - update_ssa_stats.num_virtual_mappings); - fprintf (file, "Number of total NEW -> OLD mappings: %7u\n", - update_ssa_stats.num_total_mappings); - - fprintf (file, "\nNumber of virtual symbols: %u\n", - update_ssa_stats.num_virtual_symbols); } if (!bitmap_empty_p (SYMS_TO_RENAME (cfun))) @@ -2886,8 +2836,6 @@ init_update_ssa (struct function *fn) repl_tbl = htab_create (20, repl_map_hash, repl_map_eq, repl_map_free); names_to_release = NULL; - memset (&update_ssa_stats, 0, sizeof (update_ssa_stats)); - update_ssa_stats.virtual_symbols = BITMAP_ALLOC (NULL); update_ssa_initialized_fn = fn; } @@ -2910,7 +2858,6 @@ delete_update_ssa (void) repl_tbl = NULL; bitmap_clear (SYMS_TO_RENAME (update_ssa_initialized_fn)); - BITMAP_FREE (update_ssa_stats.virtual_symbols); if (names_to_release) { @@ -2994,22 +2941,6 @@ mark_sym_for_renaming (tree sym) } -/* Register all the symbols in SET to be renamed by update_ssa. */ - -void -mark_set_for_renaming (bitmap set) -{ - bitmap_iterator bi; - unsigned i; - - if (set == NULL || bitmap_empty_p (set)) - return; - - EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi) - mark_sym_for_renaming (referenced_var (i)); -} - - /* Return true if there is any work to be done by update_ssa for function FN. */ @@ -3171,73 +3102,6 @@ insert_updated_phi_nodes_for (tree var, bitmap_head *dfs, bitmap blocks, } -/* Heuristic to determine whether SSA name mappings for virtual names - should be discarded and their symbols rewritten from scratch. When - there is a large number of mappings for virtual names, the - insertion of PHI nodes for the old names in the mappings takes - considerable more time than if we inserted PHI nodes for the - symbols instead. - - Currently the heuristic takes these stats into account: - - - Number of mappings for virtual SSA names. - - Number of distinct virtual symbols involved in those mappings. - - If the number of virtual mappings is much larger than the number of - virtual symbols, then it will be faster to compute PHI insertion - spots for the symbols. Even if this involves traversing the whole - CFG, which is what happens when symbols are renamed from scratch. */ - -static bool -switch_virtuals_to_full_rewrite_p (void) -{ - if (update_ssa_stats.num_virtual_mappings < (unsigned) MIN_VIRTUAL_MAPPINGS) - return false; - - if (update_ssa_stats.num_virtual_mappings - > (unsigned) VIRTUAL_MAPPINGS_TO_SYMS_RATIO - * update_ssa_stats.num_virtual_symbols) - return true; - - return false; -} - - -/* Remove every virtual mapping and mark all the affected virtual - symbols for renaming. */ - -static void -switch_virtuals_to_full_rewrite (void) -{ - unsigned i = 0; - sbitmap_iterator sbi; - - if (dump_file) - { - fprintf (dump_file, "\nEnabled virtual name mapping heuristic.\n"); - fprintf (dump_file, "\tNumber of virtual mappings: %7u\n", - update_ssa_stats.num_virtual_mappings); - fprintf (dump_file, "\tNumber of unique virtual symbols: %7u\n", - update_ssa_stats.num_virtual_symbols); - fprintf (dump_file, "Updating FUD-chains from top of CFG will be " - "faster than processing\nthe name mappings.\n\n"); - } - - /* Remove all virtual names from NEW_SSA_NAMES and OLD_SSA_NAMES. - Note that it is not really necessary to remove the mappings from - REPL_TBL, that would only waste time. */ - EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi) - if (!is_gimple_reg (ssa_name (i))) - RESET_BIT (new_ssa_names, i); - - EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi) - if (!is_gimple_reg (ssa_name (i))) - RESET_BIT (old_ssa_names, i); - - mark_set_for_renaming (update_ssa_stats.virtual_symbols); -} - - /* Given a set of newly created SSA names (NEW_SSA_NAMES) and a set of existing SSA names (OLD_SSA_NAMES), update the SSA form so that: @@ -3366,11 +3230,6 @@ update_ssa (unsigned update_flags) def_blocks = NULL; } - /* Heuristic to avoid massive slow downs when the replacement - mappings include lots of virtual names. */ - if (insert_phi_p && switch_virtuals_to_full_rewrite_p ()) - switch_virtuals_to_full_rewrite (); - /* If there are names defined in the replacement table, prepare definition and use sites for all the names in NEW_SSA_NAMES and OLD_SSA_NAMES. */ |