/* Callgraph based analysis of static variables. Copyright (C) 2004-2013 Free Software Foundation, Inc. Contributed by Kenneth Zadeck This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see . */ /* This file gathers information about how variables whose scope is confined to the compilation unit are used. The transitive call site specific clobber effects are computed for the variables whose scope is contained within this compilation unit. First each function and static variable initialization is analyzed to determine which local static variables are either read, written, or have their address taken. Any local static that has its address taken is removed from consideration. Once the local read and writes are determined, a transitive closure of this information is performed over the call graph to determine the worst case set of side effects of each call. In later parts of the compiler, these local and global sets are examined to make the call clobbering less traumatic, promote some statics to registers, and improve aliasing information. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "tree.h" #include "tree-flow.h" #include "tree-inline.h" #include "tree-pass.h" #include "pointer-set.h" #include "splay-tree.h" #include "ggc.h" #include "ipa-utils.h" #include "ipa-reference.h" #include "gimple.h" #include "cgraph.h" #include "flags.h" #include "diagnostic.h" #include "data-streamer.h" #include "lto-streamer.h" static void remove_node_data (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED); static void duplicate_node_data (struct cgraph_node *src, struct cgraph_node *dst, void *data ATTRIBUTE_UNUSED); /* The static variables defined within the compilation unit that are loaded or stored directly by function that owns this structure. */ struct ipa_reference_local_vars_info_d { bitmap statics_read; bitmap statics_written; }; /* Statics that are read and written by some set of functions. The local ones are based on the loads and stores local to the function. The global ones are based on the local info as well as the transitive closure of the functions that are called. */ struct ipa_reference_global_vars_info_d { bitmap statics_read; bitmap statics_written; }; /* Information we save about every function after ipa-reference is completed. */ struct ipa_reference_optimization_summary_d { bitmap statics_not_read; bitmap statics_not_written; }; typedef struct ipa_reference_local_vars_info_d *ipa_reference_local_vars_info_t; typedef struct ipa_reference_global_vars_info_d *ipa_reference_global_vars_info_t; typedef struct ipa_reference_optimization_summary_d *ipa_reference_optimization_summary_t; struct ipa_reference_vars_info_d { struct ipa_reference_local_vars_info_d local; struct ipa_reference_global_vars_info_d global; }; typedef struct ipa_reference_vars_info_d *ipa_reference_vars_info_t; /* This splay tree contains all of the static variables that are being considered by the compilation level alias analysis. */ static splay_tree reference_vars_to_consider; /* Set of all interesting module statics. A bit is set for every module static we are considering. This is added to the local info when asm code is found that clobbers all memory. */ static bitmap all_module_statics; /* Obstack holding bitmaps of local analysis (live from analysis to propagation) */ static bitmap_obstack local_info_obstack; /* Obstack holding global analysis live forever. */ static bitmap_obstack optimization_summary_obstack; /* Holders of ipa cgraph hooks: */ static struct cgraph_2node_hook_list *node_duplication_hook_holder; static struct cgraph_node_hook_list *node_removal_hook_holder; /* Vector where the reference var infos are actually stored. Indexed by UID of call graph nodes. */ static vec ipa_reference_vars_vector; static vec ipa_reference_opt_sum_vector; /* Return the ipa_reference_vars structure starting from the cgraph NODE. */ static inline ipa_reference_vars_info_t get_reference_vars_info (struct cgraph_node *node) { if (!ipa_reference_vars_vector.exists () || ipa_reference_vars_vector.length () <= (unsigned int) node->uid) return NULL; return ipa_reference_vars_vector[node->uid]; } /* Return the ipa_reference_vars structure starting from the cgraph NODE. */ static inline ipa_reference_optimization_summary_t get_reference_optimization_summary (struct cgraph_node *node) { if (!ipa_reference_opt_sum_vector.exists () || (ipa_reference_opt_sum_vector.length () <= (unsigned int) node->uid)) return NULL; return ipa_reference_opt_sum_vector[node->uid]; } /* Return the ipa_reference_vars structure starting from the cgraph NODE. */ static inline void set_reference_vars_info (struct cgraph_node *node, ipa_reference_vars_info_t info) { if (!ipa_reference_vars_vector.exists () || ipa_reference_vars_vector.length () <= (unsigned int) node->uid) ipa_reference_vars_vector.safe_grow_cleared (node->uid + 1); ipa_reference_vars_vector[node->uid] = info; } /* Return the ipa_reference_vars structure starting from the cgraph NODE. */ static inline void set_reference_optimization_summary (struct cgraph_node *node, ipa_reference_optimization_summary_t info) { if (!ipa_reference_opt_sum_vector.exists () || (ipa_reference_opt_sum_vector.length () <= (unsigned int) node->uid)) ipa_reference_opt_sum_vector.safe_grow_cleared (node->uid + 1); ipa_reference_opt_sum_vector[node->uid] = info; } /* Return a bitmap indexed by DECL_UID for the static variables that are *not* read during the execution of the function FN. Returns NULL if no data is available. */ bitmap ipa_reference_get_not_read_global (struct cgraph_node *fn) { ipa_reference_optimization_summary_t info = get_reference_optimization_summary (cgraph_function_node (fn, NULL)); if (info) return info->statics_not_read; else if (flags_from_decl_or_type (fn->symbol.decl) & ECF_LEAF) return all_module_statics; else return NULL; } /* Return a bitmap indexed by DECL_UID for the static variables that are *not* written during the execution of the function FN. Note that variables written may or may not be read during the function call. Returns NULL if no data is available. */ bitmap ipa_reference_get_not_written_global (struct cgraph_node *fn) { ipa_reference_optimization_summary_t info = get_reference_optimization_summary (fn); if (info) return info->statics_not_written; else if (flags_from_decl_or_type (fn->symbol.decl) & ECF_LEAF) return all_module_statics; else return NULL; } /* Add VAR to all_module_statics and the two reference_vars_to_consider* sets. */ static inline void add_static_var (tree var) { int uid = DECL_UID (var); gcc_assert (TREE_CODE (var) == VAR_DECL); if (dump_file) splay_tree_insert (reference_vars_to_consider, uid, (splay_tree_value)var); bitmap_set_bit (all_module_statics, uid); } /* Return true if the variable T is the right kind of static variable to perform compilation unit scope escape analysis. */ static inline bool is_proper_for_analysis (tree t) { /* If the variable has the "used" attribute, treat it as if it had a been touched by the devil. */ if (DECL_PRESERVE_P (t)) return false; /* Do not want to do anything with volatile except mark any function that uses one to be not const or pure. */ if (TREE_THIS_VOLATILE (t)) return false; /* We do not need to analyze readonly vars, we already know they do not alias. */ if (TREE_READONLY (t)) return false; /* This is a variable we care about. Check if we have seen it before, and if not add it the set of variables we care about. */ if (all_module_statics && !bitmap_bit_p (all_module_statics, DECL_UID (t))) add_static_var (t); return true; } /* Lookup the tree node for the static variable that has UID and convert the name to a string for debugging. */ static const char * get_static_name (int index) { splay_tree_node stn = splay_tree_lookup (reference_vars_to_consider, index); return fndecl_name ((tree)(stn->value)); } /* Dump a set of static vars to FILE. */ static void dump_static_vars_set_to_file (FILE *f, bitmap set) { unsigned int index; bitmap_iterator bi; if (set == NULL) return; else if (set == all_module_statics) fprintf (f, "ALL"); else EXECUTE_IF_SET_IN_BITMAP (set, 0, index, bi) { fprintf (f, "%s ", get_static_name (index)); } } /* Compute X |= Y, taking into account the possibility that either X or Y is already the maximum set. Return true if X is the maximum set after taking the union with Y. */ static bool union_static_var_sets (bitmap &x, bitmap y) { if (x != all_module_statics) { if (y == all_module_statics) { BITMAP_FREE (x); x = all_module_statics; } else if (bitmap_ior_into (x, y)) { /* The union may have reduced X to the maximum set. In that case, we want to make that visible explicitly. Even though bitmap_equal_p can be very expensive, it turns out to be an overall win to check this here for an LTO bootstrap of GCC itself. Liberally extrapoliate that result to be applicable to all cases. */ if (bitmap_equal_p (x, all_module_statics)) { BITMAP_FREE (x); x = all_module_statics; } } } return x == all_module_statics; } /* Compute X &= Y, taking into account the possibility that X may become the maximum set. */ static bool intersect_static_var_sets (bitmap &x, bitmap y) { if (x != all_module_statics) { bitmap_and_into (x, y); /* As with union_static_var_sets, reducing to the maximum set as early as possible is an overall win. */ if (bitmap_equal_p (x, all_module_statics)) { BITMAP_FREE (x); x = all_module_statics; } } return x == all_module_statics; } /* Return a copy of SET on the bitmap obstack containing SET. But if SET is NULL or the maximum set, return that instead. */ static bitmap copy_static_var_set (bitmap set) { if (set == NULL || set == all_module_statics) return set; bitmap_obstack *o = set->obstack; gcc_checking_assert (o); bitmap copy = BITMAP_ALLOC (o); bitmap_copy (copy, set); return copy; } /* Compute the union all of the statics read and written by every callee of X into X_GLOBAL->statics_read and X_GLOBAL->statics_written. X_GLOBAL is actually the set representing the cycle containing X. If the read and written sets of X_GLOBAL has been reduced to the maximum set, we don't have to look at the remaining callees. */ static void propagate_bits (ipa_reference_global_vars_info_t x_global, struct cgraph_node *x) { struct cgraph_edge *e; bool read_all = x_global->statics_read == all_module_statics; bool write_all = x_global->statics_written == all_module_statics; for (e = x->callees; e && !(read_all && write_all); e = e->next_callee) { enum availability avail; struct cgraph_node *y = cgraph_function_node (e->callee, &avail); if (!y) continue; /* Only look into nodes we can propagate something. */ int flags = flags_from_decl_or_type (y->symbol.decl); if (avail > AVAIL_OVERWRITABLE || (avail == AVAIL_OVERWRITABLE && (flags & ECF_LEAF))) { if (get_reference_vars_info (y)) { ipa_reference_vars_info_t y_info = get_reference_vars_info (y); ipa_reference_global_vars_info_t y_global = &y_info->global; /* Calls in the current cycle do not have their global set computed yet (but everything else does because we're visiting nodes in topological order). */ if (!y_global->statics_read) continue; /* If the function is const, it reads no memory even if it seems so to local analysis. */ if (flags & ECF_CONST) continue; union_static_var_sets (x_global->statics_read, y_global->statics_read); /* If the function is pure, it has no stores even if it seems so to local analysis. If we cannot return from the function, we can safely ignore the call. */ if ((flags & ECF_PURE) || cgraph_edge_cannot_lead_to_return (e)) continue; union_static_var_sets (x_global->statics_written, y_global->statics_written); } else gcc_unreachable (); } } } /* The init routine for analyzing global static variable usage. See comments at top for description. */ static void ipa_init (void) { static bool init_p = false; if (init_p) return; init_p = true; if (dump_file) reference_vars_to_consider = splay_tree_new (splay_tree_compare_ints, 0, 0); bitmap_obstack_initialize (&local_info_obstack); bitmap_obstack_initialize (&optimization_summary_obstack); all_module_statics = BITMAP_ALLOC (&optimization_summary_obstack); node_removal_hook_holder = cgraph_add_node_removal_hook (&remove_node_data, NULL); node_duplication_hook_holder = cgraph_add_node_duplication_hook (&duplicate_node_data, NULL); } /* Set up the persistent info for FN. */ static ipa_reference_local_vars_info_t init_function_info (struct cgraph_node *fn) { ipa_reference_vars_info_t info = XCNEW (struct ipa_reference_vars_info_d); /* Add the info to the tree's annotation. */ set_reference_vars_info (fn, info); info->local.statics_read = BITMAP_ALLOC (&local_info_obstack); info->local.statics_written = BITMAP_ALLOC (&local_info_obstack); return &info->local; } /* This is the main routine for finding the reference patterns for global variables within a function FN. */ static void analyze_function (struct cgraph_node *fn) { ipa_reference_local_vars_info_t local; struct ipa_ref *ref; int i; tree var; local = init_function_info (fn); for (i = 0; ipa_ref_list_reference_iterate (&fn->symbol.ref_list, i, ref); i++) { if (!is_a (ref->referred)) continue; var = ipa_ref_varpool_node (ref)->symbol.decl; if (!is_proper_for_analysis (var)) continue; switch (ref->use) { case IPA_REF_LOAD: bitmap_set_bit (local->statics_read, DECL_UID (var)); break; case IPA_REF_STORE: if (ipa_ref_cannot_lead_to_return (ref)) break; bitmap_set_bit (local->statics_written, DECL_UID (var)); break; case IPA_REF_ADDR: break; } } if (cgraph_node_cannot_return (fn)) bitmap_clear (local->statics_written); } /* Called when new clone is inserted to callgraph late. */ static void duplicate_node_data (struct cgraph_node *src, struct cgraph_node *dst, void *data ATTRIBUTE_UNUSED) { ipa_reference_optimization_summary_t ginfo; ipa_reference_optimization_summary_t dst_ginfo; ginfo = get_reference_optimization_summary (src); if (!ginfo) return; dst_ginfo = XCNEW (struct ipa_reference_optimization_summary_d); set_reference_optimization_summary (dst, dst_ginfo); dst_ginfo->statics_not_read = copy_static_var_set (ginfo->statics_not_read); dst_ginfo->statics_not_written = copy_static_var_set (ginfo->statics_not_written); } /* Called when node is removed. */ static void remove_node_data (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED) { ipa_reference_optimization_summary_t ginfo; ginfo = get_reference_optimization_summary (node); if (ginfo) { if (ginfo->statics_not_read && ginfo->statics_not_read != all_module_statics) BITMAP_FREE (ginfo->statics_not_read); if (ginfo->statics_not_written && ginfo->statics_not_written != all_module_statics) BITMAP_FREE (ginfo->statics_not_written); free (ginfo); set_reference_optimization_summary (node, NULL); } } /* Analyze each function in the cgraph to see which global or statics are read or written. */ static void generate_summary (void) { struct cgraph_node *node; unsigned int index; bitmap_iterator bi; ipa_init (); /* Process all of the functions next. */ FOR_EACH_DEFINED_FUNCTION (node) analyze_function (node); if (dump_file) EXECUTE_IF_SET_IN_BITMAP (all_module_statics, 0, index, bi) { fprintf (dump_file, "\nPromotable global:%s (uid=%u)\n", get_static_name (index), index); } if (dump_file) FOR_EACH_DEFINED_FUNCTION (node) if (cgraph_function_body_availability (node) >= AVAIL_OVERWRITABLE) { ipa_reference_local_vars_info_t l; unsigned int index; bitmap_iterator bi; l = &get_reference_vars_info (node)->local; fprintf (dump_file, "\nFunction name:%s/%i:", cgraph_node_asm_name (node), node->symbol.order); fprintf (dump_file, "\n locals read: "); if (l->statics_read) EXECUTE_IF_SET_IN_BITMAP (l->statics_read, 0, index, bi) { fprintf (dump_file, "%s ", get_static_name (index)); } fprintf (dump_file, "\n locals written: "); if (l->statics_written) EXECUTE_IF_SET_IN_BITMAP (l->statics_written, 0, index, bi) { fprintf(dump_file, "%s ", get_static_name (index)); } } } /* Set READ_ALL/WRITE_ALL based on decl flags of NODE. */ static void read_write_all_from_decl (struct cgraph_node *node, bool &read_all, bool &write_all) { tree decl = node->symbol.decl; int flags = flags_from_decl_or_type (decl); if ((flags & ECF_LEAF) && cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE) ; else if (flags & ECF_CONST) ; else if ((flags & ECF_PURE) || cgraph_node_cannot_return (node)) { read_all = true; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " %s/%i -> read all\n", cgraph_node_asm_name (node), node->symbol.order); } else { /* TODO: To be able to produce sane results, we should also handle common builtins, in particular throw. */ read_all = true; write_all = true; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " %s/%i -> read all, write all\n", cgraph_node_asm_name (node), node->symbol.order); } } /* Set READ_ALL/WRITE_ALL based on decl flags of NODE or any member in the cycle of NODE. */ static void get_read_write_all_from_node (struct cgraph_node *node, bool &read_all, bool &write_all) { struct cgraph_edge *e, *ie; /* When function is overwritable, we can not assume anything. */ if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE) read_write_all_from_decl (node, read_all, write_all); for (e = node->callees; e && !(read_all && write_all); e = e->next_callee) { enum availability avail; struct cgraph_node *callee = cgraph_function_node (e->callee, &avail); gcc_checking_assert (callee); if (avail <= AVAIL_OVERWRITABLE) read_write_all_from_decl (callee, read_all, write_all); } for (ie = node->indirect_calls; ie && !(read_all && write_all); ie = ie->next_callee) if (!(ie->indirect_info->ecf_flags & ECF_CONST)) { read_all = true; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " indirect call -> read all\n"); if (!cgraph_edge_cannot_lead_to_return (ie) && !(ie->indirect_info->ecf_flags & ECF_PURE)) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " indirect call -> write all\n"); write_all = true; } } } /* Produce the global information by preforming a transitive closure on the local information that was produced by ipa_analyze_function. */ static unsigned int propagate (void) { struct cgraph_node *node; struct varpool_node *vnode; struct cgraph_node **order = XCNEWVEC (struct cgraph_node *, cgraph_n_nodes); int order_pos; int i; if (dump_file) dump_cgraph (dump_file); ipa_discover_readonly_nonaddressable_vars (); generate_summary (); /* Now we know what vars are really statics; prune out those that aren't. */ FOR_EACH_VARIABLE (vnode) if (vnode->symbol.externally_visible || TREE_ADDRESSABLE (vnode->symbol.decl) || TREE_READONLY (vnode->symbol.decl) || !is_proper_for_analysis (vnode->symbol.decl) || !vnode->analyzed) bitmap_clear_bit (all_module_statics, DECL_UID (vnode->symbol.decl)); /* Forget info we collected "just for fun" on variables that turned out to be non-local. */ FOR_EACH_DEFINED_FUNCTION (node) { ipa_reference_local_vars_info_t node_l; node_l = &get_reference_vars_info (node)->local; intersect_static_var_sets (node_l->statics_read, all_module_statics); intersect_static_var_sets (node_l->statics_written, all_module_statics); } /* Propagate the local information through the call graph to produce the global information. All the nodes within a cycle will have the same info so we collapse cycles first. Then we can do the propagation in one pass from the leaves to the roots. */ order_pos = ipa_reduced_postorder (order, true, true, NULL); if (dump_file) ipa_print_order (dump_file, "reduced", order, order_pos); for (i = 0; i < order_pos; i++ ) { unsigned x; struct cgraph_node *w; ipa_reference_vars_info_t node_info; ipa_reference_global_vars_info_t node_g; ipa_reference_local_vars_info_t node_l; bool read_all = false; bool write_all = false; node = order[i]; if (node->alias) continue; node_info = get_reference_vars_info (node); gcc_assert (node_info); node_l = &node_info->local; node_g = &node_info->global; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "Starting cycle with %s/%i\n", cgraph_node_asm_name (node), node->symbol.order); vec cycle_nodes = ipa_get_nodes_in_cycle (node); /* If any node in a cycle is read_all or write_all, they all are. */ FOR_EACH_VEC_ELT (cycle_nodes, x, w) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " Visiting %s/%i\n", cgraph_node_asm_name (w), w->symbol.order); get_read_write_all_from_node (w, read_all, write_all); if (read_all && write_all) break; } /* Initialized the bitmaps global sets for the reduced node. */ if (read_all) node_g->statics_read = all_module_statics; else node_g->statics_read = copy_static_var_set (node_l->statics_read); if (write_all) node_g->statics_written = all_module_statics; else node_g->statics_written = copy_static_var_set (node_l->statics_written); /* Merge the sets of this cycle with all sets of callees reached from this cycle. */ FOR_EACH_VEC_ELT (cycle_nodes, x, w) { if (read_all && write_all) break; if (w != node) { ipa_reference_vars_info_t w_ri = get_reference_vars_info (w); ipa_reference_local_vars_info_t w_l = &w_ri->local; int flags = flags_from_decl_or_type (w->symbol.decl); if (!(flags & ECF_CONST)) read_all = union_static_var_sets (node_g->statics_read, w_l->statics_read); if (!(flags & ECF_PURE) && !cgraph_node_cannot_return (w)) write_all = union_static_var_sets (node_g->statics_written, w_l->statics_written); } propagate_bits (node_g, w); } /* All nodes within a cycle have the same global info bitmaps. */ FOR_EACH_VEC_ELT (cycle_nodes, x, w) { ipa_reference_vars_info_t w_ri = get_reference_vars_info (w); w_ri->global = *node_g; } cycle_nodes.release (); } if (dump_file) { for (i = 0; i < order_pos; i++) { unsigned x; struct cgraph_node *w; node = order[i]; if (node->alias) continue; fprintf (dump_file, "\nFunction name:%s/%i:", cgraph_node_asm_name (node), node->symbol.order); ipa_reference_vars_info_t node_info = get_reference_vars_info (node); ipa_reference_global_vars_info_t node_g = &node_info->global; vec cycle_nodes = ipa_get_nodes_in_cycle (node); FOR_EACH_VEC_ELT (cycle_nodes, x, w) { ipa_reference_vars_info_t w_ri = get_reference_vars_info (w); ipa_reference_local_vars_info_t w_l = &w_ri->local; if (w != node) fprintf (dump_file, "\n next cycle: %s/%i ", cgraph_node_asm_name (w), w->symbol.order); fprintf (dump_file, "\n locals read: "); dump_static_vars_set_to_file (dump_file, w_l->statics_read); fprintf (dump_file, "\n locals written: "); dump_static_vars_set_to_file (dump_file, w_l->statics_written); } cycle_nodes.release (); fprintf (dump_file, "\n globals read: "); dump_static_vars_set_to_file (dump_file, node_g->statics_read); fprintf (dump_file, "\n globals written: "); dump_static_vars_set_to_file (dump_file, node_g->statics_written); fprintf (dump_file, "\n"); } } /* Cleanup. */ FOR_EACH_DEFINED_FUNCTION (node) { ipa_reference_vars_info_t node_info; ipa_reference_global_vars_info_t node_g; ipa_reference_optimization_summary_t opt; if (node->alias) continue; node_info = get_reference_vars_info (node); if (cgraph_function_body_availability (node) > AVAIL_OVERWRITABLE || (flags_from_decl_or_type (node->symbol.decl) & ECF_LEAF)) { node_g = &node_info->global; opt = XCNEW (struct ipa_reference_optimization_summary_d); set_reference_optimization_summary (node, opt); /* Create the complimentary sets. */ if (bitmap_empty_p (node_g->statics_read)) opt->statics_not_read = all_module_statics; else { opt->statics_not_read = BITMAP_ALLOC (&optimization_summary_obstack); if (node_g->statics_read != all_module_statics) bitmap_and_compl (opt->statics_not_read, all_module_statics, node_g->statics_read); } if (bitmap_empty_p (node_g->statics_written)) opt->statics_not_written = all_module_statics; else { opt->statics_not_written = BITMAP_ALLOC (&optimization_summary_obstack); if (node_g->statics_written != all_module_statics) bitmap_and_compl (opt->statics_not_written, all_module_statics, node_g->statics_written); } } free (node_info); } ipa_free_postorder_info (); free (order); bitmap_obstack_release (&local_info_obstack); ipa_reference_vars_vector.release (); if (dump_file) splay_tree_delete (reference_vars_to_consider); reference_vars_to_consider = NULL; return 0; } /* Return true if we need to write summary of NODE. */ static bool write_node_summary_p (struct cgraph_node *node, lto_symtab_encoder_t encoder, bitmap ltrans_statics) { ipa_reference_optimization_summary_t info; /* See if we have (non-empty) info. */ if (!node->analyzed || node->global.inlined_to) return false; info = get_reference_optimization_summary (node); if (!info || (bitmap_empty_p (info->statics_not_read) && bitmap_empty_p (info->statics_not_written))) return false; /* See if we want to encode it. Encode also referenced functions since constant folding might turn it into a direct call. In future we might also want to include summaries of functions references by initializers of constant variables references in current unit. */ if (!reachable_from_this_partition_p (node, encoder) && !referenced_from_this_partition_p (&node->symbol.ref_list, encoder)) return false; /* See if the info has non-empty intersections with vars we want to encode. */ if (!bitmap_intersect_p (info->statics_not_read, ltrans_statics) && !bitmap_intersect_p (info->statics_not_written, ltrans_statics)) return false; return true; } /* Stream out BITS<RANS_STATICS as list of decls to OB. LTRANS_STATICS_BITCOUNT specify number of bits in LTRANS_STATICS or -1. When it is positive, just output -1 when BITS<RANS_STATICS == BITS<RANS_STATICS. */ static void stream_out_bitmap (struct lto_simple_output_block *ob, bitmap bits, bitmap ltrans_statics, int ltrans_statics_bitcount) { int count = 0; unsigned int index; bitmap_iterator bi; if (bits == all_module_statics) { streamer_write_hwi_stream (ob->main_stream, -1); return; } EXECUTE_IF_AND_IN_BITMAP (bits, ltrans_statics, 0, index, bi) count ++; if (count == ltrans_statics_bitcount) { streamer_write_hwi_stream (ob->main_stream, -1); return; } streamer_write_hwi_stream (ob->main_stream, count); if (!count) return; EXECUTE_IF_AND_IN_BITMAP (bits, ltrans_statics, 0, index, bi) { tree decl = (tree)splay_tree_lookup (reference_vars_to_consider, index)->value; lto_output_var_decl_index(ob->decl_state, ob->main_stream, decl); } } /* Serialize the ipa info for lto. */ static void ipa_reference_write_optimization_summary (void) { struct lto_simple_output_block *ob = lto_create_simple_output_block (LTO_section_ipa_reference); unsigned int count = 0; int ltrans_statics_bitcount = 0; lto_symtab_encoder_t encoder = ob->decl_state->symtab_node_encoder; bitmap ltrans_statics = BITMAP_ALLOC (NULL); int i; reference_vars_to_consider = splay_tree_new (splay_tree_compare_ints, 0, 0); /* See what variables we are interested in. */ for (i = 0; i < lto_symtab_encoder_size (encoder); i++) { symtab_node snode = lto_symtab_encoder_deref (encoder, i); varpool_node *vnode = dyn_cast (snode); if (vnode && bitmap_bit_p (all_module_statics, DECL_UID (vnode->symbol.decl)) && referenced_from_this_partition_p (&vnode->symbol.ref_list, encoder)) { tree decl = vnode->symbol.decl; bitmap_set_bit (ltrans_statics, DECL_UID (decl)); splay_tree_insert (reference_vars_to_consider, DECL_UID (decl), (splay_tree_value)decl); ltrans_statics_bitcount ++; } } if (ltrans_statics_bitcount) for (i = 0; i < lto_symtab_encoder_size (encoder); i++) { symtab_node snode = lto_symtab_encoder_deref (encoder, i); cgraph_node *cnode = dyn_cast (snode); if (cnode && write_node_summary_p (cnode, encoder, ltrans_statics)) count++; } streamer_write_uhwi_stream (ob->main_stream, count); if (count) stream_out_bitmap (ob, ltrans_statics, ltrans_statics, -1); /* Process all of the functions. */ if (ltrans_statics_bitcount) for (i = 0; i < lto_symtab_encoder_size (encoder); i++) { symtab_node snode = lto_symtab_encoder_deref (encoder, i); cgraph_node *cnode = dyn_cast (snode); if (cnode && write_node_summary_p (cnode, encoder, ltrans_statics)) { ipa_reference_optimization_summary_t info; int node_ref; info = get_reference_optimization_summary (cnode); node_ref = lto_symtab_encoder_encode (encoder, snode); streamer_write_uhwi_stream (ob->main_stream, node_ref); stream_out_bitmap (ob, info->statics_not_read, ltrans_statics, ltrans_statics_bitcount); stream_out_bitmap (ob, info->statics_not_written, ltrans_statics, ltrans_statics_bitcount); } } BITMAP_FREE (ltrans_statics); lto_destroy_simple_output_block (ob); splay_tree_delete (reference_vars_to_consider); } /* Deserialize the ipa info for lto. */ static void ipa_reference_read_optimization_summary (void) { struct lto_file_decl_data ** file_data_vec = lto_get_file_decl_data (); struct lto_file_decl_data * file_data; unsigned int j = 0; bitmap_obstack_initialize (&optimization_summary_obstack); node_removal_hook_holder = cgraph_add_node_removal_hook (&remove_node_data, NULL); node_duplication_hook_holder = cgraph_add_node_duplication_hook (&duplicate_node_data, NULL); all_module_statics = BITMAP_ALLOC (&optimization_summary_obstack); while ((file_data = file_data_vec[j++])) { const char *data; size_t len; struct lto_input_block *ib = lto_create_simple_input_block (file_data, LTO_section_ipa_reference, &data, &len); if (ib) { unsigned int i; unsigned int f_count = streamer_read_uhwi (ib); int b_count; if (!f_count) continue; b_count = streamer_read_hwi (ib); if (dump_file) fprintf (dump_file, "all module statics:"); for (i = 0; i < (unsigned int)b_count; i++) { unsigned int var_index = streamer_read_uhwi (ib); tree v_decl = lto_file_decl_data_get_var_decl (file_data, var_index); bitmap_set_bit (all_module_statics, DECL_UID (v_decl)); if (dump_file) fprintf (dump_file, " %s", fndecl_name (v_decl)); } for (i = 0; i < f_count; i++) { unsigned int j, index; struct cgraph_node *node; ipa_reference_optimization_summary_t info; int v_count; lto_symtab_encoder_t encoder; index = streamer_read_uhwi (ib); encoder = file_data->symtab_node_encoder; node = cgraph (lto_symtab_encoder_deref (encoder, index)); info = XCNEW (struct ipa_reference_optimization_summary_d); set_reference_optimization_summary (node, info); info->statics_not_read = BITMAP_ALLOC (&optimization_summary_obstack); info->statics_not_written = BITMAP_ALLOC (&optimization_summary_obstack); if (dump_file) fprintf (dump_file, "\nFunction name:%s/%i:\n static not read:", cgraph_node_asm_name (node), node->symbol.order); /* Set the statics not read. */ v_count = streamer_read_hwi (ib); if (v_count == -1) { info->statics_not_read = all_module_statics; if (dump_file) fprintf (dump_file, " all module statics"); } else for (j = 0; j < (unsigned int)v_count; j++) { unsigned int var_index = streamer_read_uhwi (ib); tree v_decl = lto_file_decl_data_get_var_decl (file_data, var_index); bitmap_set_bit (info->statics_not_read, DECL_UID (v_decl)); if (dump_file) fprintf (dump_file, " %s", fndecl_name (v_decl)); } if (dump_file) fprintf (dump_file, "\n static not written:"); /* Set the statics not written. */ v_count = streamer_read_hwi (ib); if (v_count == -1) { info->statics_not_written = all_module_statics; if (dump_file) fprintf (dump_file, " all module statics"); } else for (j = 0; j < (unsigned int)v_count; j++) { unsigned int var_index = streamer_read_uhwi (ib); tree v_decl = lto_file_decl_data_get_var_decl (file_data, var_index); bitmap_set_bit (info->statics_not_written, DECL_UID (v_decl)); if (dump_file) fprintf (dump_file, " %s", fndecl_name (v_decl)); } if (dump_file) fprintf (dump_file, "\n"); } lto_destroy_simple_input_block (file_data, LTO_section_ipa_reference, ib, data, len); } else /* Fatal error here. We do not want to support compiling ltrans units with different version of compiler or different flags than the WPA unit, so this should never happen. */ fatal_error ("ipa reference summary is missing in ltrans unit"); } } static bool gate_reference (void) { return (flag_ipa_reference /* Don't bother doing anything if the program has errors. */ && !seen_error ()); } struct ipa_opt_pass_d pass_ipa_reference = { { IPA_PASS, "static-var", /* name */ OPTGROUP_NONE, /* optinfo_flags */ gate_reference, /* gate */ propagate, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_IPA_REFERENCE, /* tv_id */ 0, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ 0 /* todo_flags_finish */ }, NULL, /* generate_summary */ NULL, /* write_summary */ NULL, /* read_summary */ ipa_reference_write_optimization_summary,/* write_optimization_summary */ ipa_reference_read_optimization_summary,/* read_optimization_summary */ NULL, /* stmt_fixup */ 0, /* TODOs */ NULL, /* function_transform */ NULL /* variable_transform */ };