nsz Git - libfirm/blob - ir/be/beirgmod.c

   1 /*
   2  * This file is part of libFirm.
   3  * Copyright (C) 2012 University of Karlsruhe.
   4  */
   5
   6 /**
   7  * @file
   8  * @brief       Backend IRG modification routines.
   9  * @author      Sebastian Hack, Daniel Grund, Matthias Braun, Christian Wuerdig
  10  * @date        04.05.2005
  11  *
  12  * This file contains the following IRG modifications for be routines:
  13  * - insertion of Perm nodes
  14  * - empty block elimination
  15  * - a simple dead node elimination (set inputs of unreachable nodes to BAD)
  16  */
  17 #include "config.h"
  18
  19 #include <stdlib.h>
  20
  21 #include "hashptr.h"
  22 #include "pdeq.h"
  23 #include "pset.h"
  24 #include "pmap.h"
  25 #include "util.h"
  26 #include "debug.h"
  27 #include "error.h"
  28 #include "xmalloc.h"
  29
  30 #include "irflag_t.h"
  31 #include "ircons_t.h"
  32 #include "irnode_t.h"
  33 #include "ircons_t.h"
  34 #include "irmode_t.h"
  35 #include "irdom_t.h"
  36 #include "iredges_t.h"
  37 #include "irgraph_t.h"
  38 #include "irgopt.h"
  39 #include "irgmod.h"
  40 #include "irprintf.h"
  41 #include "irgwalk.h"
  42
  43 #include "be_t.h"
  44 #include "bechordal_t.h"
  45 #include "bearch.h"
  46 #include "besched.h"
  47 #include "belive_t.h"
  48 #include "benode.h"
  49 #include "beutil.h"
  50 #include "beinsn_t.h"
  51 #include "bessaconstr.h"
  52 #include "beirg.h"
  53 #include "beirgmod.h"
  54 #include "bemodule.h"
  55
  56 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  57
  58 static int cmp_node_nr(const void *a, const void *b)
  59 {
  60         ir_node **p1 = (ir_node**)a;
  61         ir_node **p2 = (ir_node**)b;
  62         long      n1 = get_irn_node_nr(*p1);
  63         long      n2 = get_irn_node_nr(*p2);
  64         return (n1>n2) - (n1<n2);
  65 }
  66
  67 /*
  68   ___                     _     ____
  69  |_ _|_ __  ___  ___ _ __| |_  |  _ \ ___ _ __ _ __ ___
  70   | || '_ \/ __|/ _ \ '__| __| | |_) / _ \ '__| '_ ` _ \
  71   | || | | \__ \  __/ |  | |_  |  __/  __/ |  | | | | | |
  72  |___|_| |_|___/\___|_|   \__| |_|   \___|_|  |_| |_| |_|
  73
  74 */
  75
  76 ir_node *insert_Perm_before(ir_graph *irg, const arch_register_class_t *cls,
  77                                                    ir_node *pos)
  78 {
  79         be_lv_t     *lv = be_get_irg_liveness(irg);
  80         ir_nodeset_t live;
  81
  82         ir_node *perm, **nodes;
  83         size_t i, n;
  84
  85         DBG((dbg, LEVEL_1, "Insert Perm before: %+F\n", pos));
  86
  87         ir_nodeset_init(&live);
  88         be_liveness_nodes_live_before(lv, cls, pos, &live);
  89
  90         n = ir_nodeset_size(&live);
  91         if (n == 0) {
  92                 ir_nodeset_destroy(&live);
  93                 return NULL;
  94         }
  95
  96         nodes = XMALLOCN(ir_node*, n);
  97
  98         DBG((dbg, LEVEL_1, "live:\n"));
  99         i = 0;
 100         foreach_ir_nodeset(&live, irn, iter) {
 101                 DBG((dbg, LEVEL_1, "\t%+F\n", irn));
 102                 nodes[i] = irn;
 103                 i++;
 104         }
 105         ir_nodeset_destroy(&live);
 106         /* make the input order deterministic */
 107         qsort(nodes, n, sizeof(nodes[0]), cmp_node_nr);
 108
 109         ir_node *const bl = get_nodes_block(pos);
 110         perm = be_new_Perm(cls, bl, n, nodes);
 111         sched_add_before(pos, perm);
 112         free(nodes);
 113
 114         for (i = 0; i < n; ++i) {
 115                 ir_node *perm_op = get_irn_n(perm, i);
 116                 be_ssa_construction_env_t senv;
 117
 118                 ir_mode *mode = get_irn_mode(perm_op);
 119                 ir_node *proj = new_r_Proj(perm, mode, i);
 120
 121                 be_ssa_construction_init(&senv, irg);
 122                 be_ssa_construction_add_copy(&senv, perm_op);
 123                 be_ssa_construction_add_copy(&senv, proj);
 124                 be_ssa_construction_fix_users(&senv, perm_op);
 125                 be_ssa_construction_update_liveness_phis(&senv, lv);
 126                 be_liveness_update(lv, perm_op);
 127                 be_liveness_update(lv, proj);
 128                 be_ssa_construction_destroy(&senv);
 129         }
 130
 131         return perm;
 132 }
 133
 134 static int blocks_removed;
 135
 136 /**
 137  * Post-block-walker: Find blocks containing only one jump and
 138  * remove them.
 139  */
 140 static void remove_empty_block(ir_node *block)
 141 {
 142         int        i;
 143         int        arity;
 144         ir_node   *pred;
 145         ir_node   *succ_block;
 146         ir_node   *jump = NULL;
 147         ir_graph  *irg = get_irn_irg(block);
 148         ir_entity *entity;
 149
 150         if (irn_visited_else_mark(block))
 151                 return;
 152
 153         if (get_Block_n_cfgpreds(block) != 1)
 154                 goto check_preds;
 155
 156         sched_foreach(block, node) {
 157                 if (! is_Jmp(node)
 158                                 && !(arch_get_irn_flags(node) & arch_irn_flags_simple_jump))
 159                         goto check_preds;
 160                 if (jump != NULL) {
 161                         /* we should never have 2 jumps in a block */
 162                         panic("found 2 jumps in a block");
 163                 }
 164                 jump = node;
 165         }
 166
 167         if (jump == NULL)
 168                 goto check_preds;
 169
 170         entity     = get_Block_entity(block);
 171         pred       = get_Block_cfgpred(block, 0);
 172         succ_block = NULL;
 173         foreach_out_edge_safe(jump, edge) {
 174                 int pos = get_edge_src_pos(edge);
 175
 176                 assert(succ_block == NULL);
 177                 succ_block = get_edge_src_irn(edge);
 178                 if (get_Block_entity(succ_block) != NULL && entity != NULL) {
 179                         /*
 180                          * Currently we can add only one label for a block.
 181                          * Therefore we cannot combine them if  both block already have one.
 182                          */
 183                         goto check_preds;
 184                 }
 185
 186                 set_irn_n(succ_block, pos, pred);
 187         }
 188
 189         if (entity != NULL) {
 190                 /* move the label to the successor block */
 191                 set_Block_entity(succ_block, entity);
 192         }
 193
 194         /* there can be some non-scheduled Pin nodes left in the block, move them
 195          * to the succ block (Pin) or pred block (Sync) */
 196         foreach_out_edge_safe(block, edge) {
 197                 ir_node *const node = get_edge_src_irn(edge);
 198
 199                 if (node == jump)
 200                         continue;
 201                 /* we simply kill Pins, because there are some strange interactions
 202                  * between jump threading, which produce PhiMs with Pins, we simply
 203                  * kill the pins here, everything is scheduled anyway */
 204                 if (is_Pin(node)) {
 205                         exchange(node, get_Pin_op(node));
 206                         continue;
 207                 }
 208                 if (is_Sync(node)) {
 209                         set_nodes_block(node, get_nodes_block(pred));
 210                         continue;
 211                 }
 212                 if (is_End(node)) { /* End-keep, reroute it to the successor */
 213                         int pos = get_edge_src_pos(edge);
 214                         set_irn_n(node, pos, succ_block);
 215                         continue;
 216                 }
 217                 panic("Unexpected node %+F in block %+F with empty schedule", node, block);
 218         }
 219
 220         set_Block_cfgpred(block, 0, new_r_Bad(irg, mode_X));
 221         kill_node(jump);
 222         blocks_removed = 1;
 223
 224         /* check predecessor */
 225         remove_empty_block(get_nodes_block(pred));
 226         return;
 227
 228 check_preds:
 229         arity = get_Block_n_cfgpreds(block);
 230         for (i = 0; i < arity; ++i) {
 231                 ir_node *pred = get_Block_cfgpred_block(block, i);
 232                 remove_empty_block(pred);
 233         }
 234 }
 235
 236 /* removes basic blocks that just contain a jump instruction */
 237 int be_remove_empty_blocks(ir_graph *irg)
 238 {
 239         ir_node *end;
 240         int      i, arity;
 241
 242         blocks_removed = 0;
 243
 244         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
 245         inc_irg_visited(irg);
 246         remove_empty_block(get_irg_end_block(irg));
 247         end   = get_irg_end(irg);
 248         arity = get_irn_arity(end);
 249         for (i = 0; i < arity; ++i) {
 250                 ir_node *pred = get_irn_n(end, i);
 251                 if (!is_Block(pred))
 252                         continue;
 253                 remove_empty_block(pred);
 254         }
 255         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
 256
 257         if (blocks_removed) {
 258                 /* invalidate analysis info */
 259                 clear_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE);
 260         }
 261         return blocks_removed;
 262 }
 263
 264 //---------------------------------------------------------------------------
 265
 266 typedef struct remove_dead_nodes_env_t_ {
 267         bitset_t *reachable;
 268         ir_graph *irg;
 269         be_lv_t  *lv;
 270 } remove_dead_nodes_env_t;
 271
 272 /**
 273  * Post-walker: remember all visited nodes in a bitset.
 274  */
 275 static void mark_dead_nodes_walker(ir_node *node, void *data)
 276 {
 277         remove_dead_nodes_env_t *env = (remove_dead_nodes_env_t*) data;
 278         bitset_set(env->reachable, get_irn_idx(node));
 279 }
 280
 281 /**
 282  * Post-block-walker:
 283  * Walk through the schedule of every block and remove all dead nodes from it.
 284  */
 285 static void remove_dead_nodes_walker(ir_node *block, void *data)
 286 {
 287         remove_dead_nodes_env_t *env = (remove_dead_nodes_env_t*) data;
 288
 289         sched_foreach_safe(block, node) {
 290                 if (bitset_is_set(env->reachable, get_irn_idx(node)))
 291                         continue;
 292
 293                 if (env->lv != NULL)
 294                         be_liveness_remove(env->lv, node);
 295                 sched_remove(node);
 296
 297                 /* kill projs */
 298                 if (get_irn_mode(node) == mode_T) {
 299                         foreach_out_edge_safe(node, edge) {
 300                                 ir_node *proj = get_edge_src_irn(edge);
 301                                 if (!is_Proj(proj))
 302                                         continue;
 303                                 if (env->lv != NULL)
 304                                         be_liveness_remove(env->lv, proj);
 305                                 kill_node(proj);
 306                         }
 307                 }
 308                 kill_node(node);
 309         }
 310 }
 311
 312 void be_remove_dead_nodes_from_schedule(ir_graph *irg)
 313 {
 314         remove_dead_nodes_env_t env;
 315         env.reachable = bitset_alloca(get_irg_last_idx(irg));
 316         env.lv        = be_get_irg_liveness(irg);
 317         env.irg       = irg;
 318
 319         // mark all reachable nodes
 320         irg_walk_graph(irg, mark_dead_nodes_walker, NULL, &env);
 321
 322         // walk schedule and remove non-marked nodes
 323         irg_block_walk_graph(irg, remove_dead_nodes_walker, NULL, &env);
 324 }
 325
 326 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_irgmod)
 327 void be_init_irgmod(void)
 328 {
 329         FIRM_DBG_REGISTER(dbg, "firm.be.irgmod");
 330 }