nsz Git - libfirm/blob - ir/opt/ircgopt.c

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief    Removal of unreachable methods.
  23  * @author   Hubert Schmid
  24  * @date     09.06.2002
  25  * @version  $Id$
  26  */
  27
  28 /*
  29  * Entfernen von nicht erreichbaren (aufrufbaren) Methoden. Die Menge
  30  * der nicht erreichbaren Methoden wird aus der Abschätzung der
  31  * Aufrufrelation bestimmt.
  32  */
  33 #include "config.h"
  34
  35 #include "ircgopt.h"
  36
  37 #include "debug.h"
  38 #include "array.h"
  39 #include "irprog.h"
  40 #include "irgwalk.h"
  41 #include "irloop_t.h"
  42 #include "irflag_t.h"
  43 #include "ircons.h"
  44 #include "cgana.h"
  45 #include "irtools.h"
  46
  47 DEBUG_ONLY(static firm_dbg_module_t *dbg);
  48
  49 /**
  50  * Walker: adds Call operations to a head's link list.
  51  */
  52 static void collect_call(ir_node *node, void *env) {
  53         ir_node *head = env;
  54
  55         if (is_Call(node)) {
  56                 set_irn_link(node, get_irn_link(head));
  57                 set_irn_link(head, node);
  58         }
  59 }
  60
  61 /**
  62  * Type walker, set the peculiarity of entities which graphs
  63  * gets removed to peculiarity_description.
  64  */
  65 static void make_entity_to_description(type_or_ent tore, void *env) {
  66         if (is_entity(tore.ent)) {
  67                 ir_entity *ent = tore.ent;
  68
  69                 if ((is_Method_type(get_entity_type(ent)))                        &&
  70                         (get_entity_peculiarity(ent) != peculiarity_description)      &&
  71                         (get_entity_visibility(ent)  != visibility_external_allocated)   ) {
  72                                 ir_entity *impl = get_SymConst_entity(get_atomic_ent_value(ent));
  73                                 if (get_entity_link(impl) != env) {
  74                                         set_entity_peculiarity(ent, peculiarity_description);
  75                                 }
  76                 }
  77         }
  78 }
  79
  80 /* garbage collect methods: mark and remove */
  81 void gc_irgs(int n_keep, ir_entity ** keep_arr) {
  82         void * MARK = &MARK; /* @@@ gefaehrlich!!! Aber wir markieren hoechstens zu viele ... */
  83         int i;
  84
  85         FIRM_DBG_REGISTER(dbg, "firm.opt.cgopt");
  86
  87         if (n_keep >= get_irp_n_irgs()) {
  88                 /* Shortcut. Obviously we have to keep all methods. */
  89                 return;
  90         }
  91
  92         DB((dbg, LEVEL_1, "dead method elimination\n"));
  93
  94         /* Mark entities that are alive.  */
  95         if (n_keep > 0) {
  96                 ir_entity **marked = NEW_ARR_F(ir_entity *, n_keep);
  97                 for (i = 0; i < n_keep; ++i) {
  98                         marked[i] = keep_arr[i];
  99                         set_entity_link(marked[i], MARK);
 100                         DB((dbg, LEVEL_1, "  method %+F kept alive.\n", marked[i]));
 101                 }
 102
 103                 for (i = 0; i < ARR_LEN(marked); ++i) {
 104                         /* check for extern methods, these don't have an IRG */
 105                         if (get_entity_visibility(marked[i]) != visibility_external_allocated) {
 106                                 ir_graph *irg = get_entity_irg(marked[i]);
 107                                 ir_node *node = get_irg_end(irg);
 108
 109                                 /* collect calls */
 110                                 ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
 111                                 irg_walk_graph(irg, firm_clear_link, collect_call, node);
 112
 113                                 /* iterate calls */
 114                                 for (node = get_irn_link(node); node; node = get_irn_link(node)) {
 115                                         int i;
 116                                         assert(is_Call(node));
 117
 118                                         for (i = get_Call_n_callees(node) - 1; i >= 0; --i) {
 119                                                 ir_entity *ent = get_Call_callee(node, i);
 120
 121                                                 if (get_entity_irg(ent) && get_entity_link(ent) != MARK) {
 122                                                         set_entity_link(ent, MARK);
 123                                                         ARR_APP1(ir_entity *, marked, ent);
 124
 125                                                         DB((dbg, LEVEL_1, "  method %+F can be called from Call %+F: kept alive.\n",
 126                                                             ent, node));
 127                                                 }
 128                                         }
 129                                 }
 130                                 ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
 131                         }
 132                 }
 133                 DEL_ARR_F(marked);
 134         }
 135
 136         /* clean */
 137         type_walk(make_entity_to_description, NULL, MARK);
 138         for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
 139                 ir_graph  *irg = get_irp_irg(i);
 140                 ir_entity *ent = get_irg_entity(irg);
 141                 /* Removing any graph invalidates all interprocedural loop trees. */
 142                 if (get_irg_loopinfo_state(irg) == loopinfo_ip_consistent ||
 143                     get_irg_loopinfo_state(irg) == loopinfo_ip_inconsistent) {
 144                         free_loop_information(irg);
 145                 }
 146                 if ((get_entity_visibility(ent) == visibility_local) && (get_entity_link(ent) != MARK)) {
 147
 148                         DB((dbg, LEVEL_1, "  freeing method %+F\n",     ent));
 149                         remove_irp_irg(irg);
 150                         set_entity_peculiarity(ent, peculiarity_description);
 151                 }
 152                 set_entity_link(ent, NULL);
 153         }
 154 }
 155
 156 /**
 157  * Wrapper for running gc_irgs() as an ir_prog pass.
 158  */
 159 static void pass_wrapper(void)
 160 {
 161     ir_entity **keep_methods;
 162     int         arr_len;
 163
 164     /* Analysis that finds the free methods,
 165        i.e. methods that are dereferenced.
 166        Optimizes polymorphic calls :-). */
 167     cgana(&arr_len, &keep_methods);
 168
 169     /* Remove methods that are never called. */
 170     gc_irgs(arr_len, keep_methods);
 171
 172     free(keep_methods);
 173 }
 174
 175 ir_prog_pass_t *gc_irgs_pass(const char *name, int verify, int dump)
 176 {
 177         return def_prog_pass(name ? name : "cgana", verify, dump, pass_wrapper);
 178 }