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 #include "irpass.h"
  47
  48 DEBUG_ONLY(static firm_dbg_module_t *dbg);
  49
  50 /**
  51  * Walker: adds Call operations to a head's link list.
  52  */
  53 static void collect_call(ir_node *node, void *env) {
  54         ir_node *head = env;
  55
  56         if (is_Call(node)) {
  57                 set_irn_link(node, get_irn_link(head));
  58                 set_irn_link(head, node);
  59         }
  60 }
  61
  62 /**
  63  * Type walker, set the peculiarity of entities which graphs
  64  * gets removed to peculiarity_description.
  65  */
  66 static void make_entity_to_description(type_or_ent tore, void *env) {
  67         if (is_entity(tore.ent)) {
  68                 ir_entity *ent = tore.ent;
  69
  70                 if ((is_Method_type(get_entity_type(ent)))                        &&
  71                         (get_entity_peculiarity(ent) != peculiarity_description)      &&
  72                         (get_entity_visibility(ent)  != visibility_external_allocated)   ) {
  73                                 ir_entity *impl = get_SymConst_entity(get_atomic_ent_value(ent));
  74                                 if (get_entity_link(impl) != env) {
  75                                         set_entity_peculiarity(ent, peculiarity_description);
  76                                 }
  77                 }
  78         }
  79 }
  80
  81 /* garbage collect methods: mark and remove */
  82 void gc_irgs(int n_keep, ir_entity ** keep_arr) {
  83         void * MARK = &MARK; /* @@@ gefaehrlich!!! Aber wir markieren hoechstens zu viele ... */
  84         int i;
  85
  86         FIRM_DBG_REGISTER(dbg, "firm.opt.cgopt");
  87
  88         if (n_keep >= get_irp_n_irgs()) {
  89                 /* Shortcut. Obviously we have to keep all methods. */
  90                 return;
  91         }
  92
  93         DB((dbg, LEVEL_1, "dead method elimination\n"));
  94
  95         /* Mark entities that are alive.  */
  96         if (n_keep > 0) {
  97                 ir_entity **marked = NEW_ARR_F(ir_entity *, n_keep);
  98                 for (i = 0; i < n_keep; ++i) {
  99                         marked[i] = keep_arr[i];
 100                         set_entity_link(marked[i], MARK);
 101                         DB((dbg, LEVEL_1, "  method %+F kept alive.\n", marked[i]));
 102                 }
 103
 104                 for (i = 0; i < ARR_LEN(marked); ++i) {
 105                         /* check for extern methods, these don't have an IRG */
 106                         if (get_entity_visibility(marked[i]) != visibility_external_allocated) {
 107                                 ir_graph *irg = get_entity_irg(marked[i]);
 108                                 ir_node *node = get_irg_end(irg);
 109
 110                                 /* collect calls */
 111                                 ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
 112                                 irg_walk_graph(irg, firm_clear_link, collect_call, node);
 113
 114                                 /* iterate calls */
 115                                 for (node = get_irn_link(node); node; node = get_irn_link(node)) {
 116                                         int i;
 117                                         assert(is_Call(node));
 118
 119                                         for (i = get_Call_n_callees(node) - 1; i >= 0; --i) {
 120                                                 ir_entity *ent = get_Call_callee(node, i);
 121
 122                                                 if (get_entity_irg(ent) && get_entity_link(ent) != MARK) {
 123                                                         set_entity_link(ent, MARK);
 124                                                         ARR_APP1(ir_entity *, marked, ent);
 125
 126                                                         DB((dbg, LEVEL_1, "  method %+F can be called from Call %+F: kept alive.\n",
 127                                                             ent, node));
 128                                                 }
 129                                         }
 130                                 }
 131                                 ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
 132                         }
 133                 }
 134                 DEL_ARR_F(marked);
 135         }
 136
 137         /* clean */
 138         type_walk(make_entity_to_description, NULL, MARK);
 139         for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
 140                 ir_graph  *irg = get_irp_irg(i);
 141                 ir_entity *ent = get_irg_entity(irg);
 142                 /* Removing any graph invalidates all interprocedural loop trees. */
 143                 if (get_irg_loopinfo_state(irg) == loopinfo_ip_consistent ||
 144                     get_irg_loopinfo_state(irg) == loopinfo_ip_inconsistent) {
 145                         free_loop_information(irg);
 146                 }
 147                 if ((get_entity_visibility(ent) == visibility_local) && (get_entity_link(ent) != MARK)) {
 148
 149                         DB((dbg, LEVEL_1, "  freeing method %+F\n",     ent));
 150                         remove_irp_irg(irg);
 151                         set_entity_peculiarity(ent, peculiarity_description);
 152                 }
 153                 set_entity_link(ent, NULL);
 154         }
 155 }
 156
 157 /**
 158  * Wrapper for running gc_irgs() as an ir_prog pass.
 159  */
 160 static void pass_wrapper(void)
 161 {
 162     ir_entity **keep_methods;
 163     int         arr_len;
 164
 165     /* Analysis that finds the free methods,
 166        i.e. methods that are dereferenced.
 167        Optimizes polymorphic calls :-). */
 168     cgana(&arr_len, &keep_methods);
 169
 170     /* Remove methods that are never called. */
 171     gc_irgs(arr_len, keep_methods);
 172
 173     free(keep_methods);
 174 }
 175
 176 ir_prog_pass_t *gc_irgs_pass(const char *name)
 177 {
 178         return def_prog_pass(name ? name : "cgana", pass_wrapper);
 179 }