Prevent beuses from choking on basic blocks without control flow successors.
[libfirm] / ir / be / beuses.c
index d9cf998..dcef874 100644 (file)
@@ -1,14 +1,33 @@
-/**
- * @file   beuse.c
- * @date   27.06.2005
- * @author Sebastian Hack
+/*
+ * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
+ *
+ * This file is part of libFirm.
  *
- * Methods to compute when a value will be used again.
+ * This file may be distributed and/or modified under the terms of the
+ * GNU General Public License version 2 as published by the Free Software
+ * Foundation and appearing in the file LICENSE.GPL included in the
+ * packaging of this file.
  *
- * Copyright (C) 2005 Universitaet Karlsruhe
- * Released under the GPL
+ * Licensees holding valid libFirm Professional Edition licenses may use
+ * this file in accordance with the libFirm Commercial License.
+ * Agreement provided with the Software.
+ *
+ * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+ * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE.
  */
 
+/**
+ * @file
+ * @brief       Methods to compute when a value will be used again.
+ * @author      Sebastian Hack, Matthias Braun
+ * @date        27.06.2005
+ * @version     $Id$
+ */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
 #include <limits.h>
 #include <stdlib.h>
 
 #include "benode_t.h"
 #include "besched_t.h"
 #include "beirgmod.h"
-#include "bearch.h"
-#include "beuses_t.h"
-#include "benodesets.h"
+#include "bearch_t.h"
+#include "beuses.h"
 
-#define DBG_LEVEL SET_LEVEL_0
+#define SCAN_INTERBLOCK_USES
 
 typedef struct _be_use_t {
-       const ir_node *bl;
-       const ir_node *irn;
+       const ir_node *block;
+       const ir_node *node;
+       int outermost_loop;
        unsigned next_use;
+       unsigned visited;
 } be_use_t;
 
 struct _be_uses_t {
-  set *uses;
-  ir_graph *irg;
-  const be_lv_t *lv;
-  const arch_env_t *arch_env;
-  DEBUG_ONLY(firm_dbg_module_t *dbg;)
+       set *uses;
+       ir_graph *irg;
+       const be_lv_t *lv;
+       unsigned visited_counter;
+       DEBUG_ONLY(firm_dbg_module_t *dbg;)
 };
 
 static int cmp_use(const void *a, const void *b, size_t n)
 {
-  const be_use_t *p = a;
-  const be_use_t *q = b;
-  return !(p->bl == q->bl && p->irn == q->irn);
+       const be_use_t *p = a;
+       const be_use_t *q = b;
+       (void) n;
+
+       return !(p->block == q->block && p->node == q->node);
 }
 
-static INLINE be_use_t *get_or_set_use(be_uses_t *uses,
-    const ir_node *bl, const ir_node *def, unsigned next_use)
+static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
+                                                                 unsigned from_step, const ir_node *def,
+                                                                 int skip_from_uses);
+
+static const be_use_t *get_or_set_use_block(be_uses_t *env,
+                                            const ir_node *block,
+                                            const ir_node *def)
 {
-  unsigned hash = HASH_COMBINE(nodeset_hash(bl), nodeset_hash(def));
-  be_use_t templ;
-  be_use_t* result;
+       unsigned hash = HASH_COMBINE(hash_irn(block), hash_irn(def));
+       be_use_t temp;
+       be_use_t* result;
+
+       temp.block = block;
+       temp.node = def;
+       result = set_find(env->uses, &temp, sizeof(temp), hash);
+
+       if(result == NULL) {
+               // insert templ first as we might end in a loop in the get_next_use
+               // call otherwise
+               temp.next_use = USES_INFINITY;
+               temp.outermost_loop = -1;
+               temp.visited = 0;
+               result = set_insert(env->uses, &temp, sizeof(temp), hash);
+       }
 
-  templ.bl = bl;
-  templ.irn = def;
-  templ.next_use = be_get_next_use(uses, sched_first(bl), 0, def, 0);
-  result = set_insert(uses->uses, &templ, sizeof(templ), hash);
+       if(result->outermost_loop < 0 && result->visited < env->visited_counter) {
+               be_next_use_t next_use;
 
-  return result;
-}
+               result->visited = env->visited_counter;
+               next_use = get_next_use(env, sched_first(block), 0, def, 0);
+               if(next_use.outermost_loop >= 0) {
+                       result->next_use = next_use.time;
+                       result->outermost_loop = next_use.outermost_loop;
+                       DBG((env->dbg, LEVEL_5, "Setting nextuse of %+F in block %+F to %u (outermostloop %d)\n", def, block, result->next_use, result->outermost_loop));
+               }
+       }
 
-unsigned be_get_next_use(be_uses_t *uses, const ir_node *from,
-    unsigned from_step, const ir_node *def, int skip_from_uses);
+       return result;
+}
 
-static unsigned get_next_use_bl(be_uses_t *uses, const ir_node *bl,
-    const ir_node *def)
+static int be_is_phi_argument(const ir_node *block, const ir_node *def)
 {
-  be_use_t *u = get_or_set_use(uses, bl, def, 0);
+       ir_node *node;
+       ir_node *succ_block = NULL;
+       const ir_edge_t *edge;
+       int arity, i;
+
+#if 1
+       if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) < 1)
+#else
+       if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) != 1)
+#endif
+               return 0;
+
+       foreach_block_succ(block, edge) {
+               succ_block = get_edge_src_irn(edge);
+               break;
+       }
+
+       arity = get_Block_n_cfgpreds(succ_block);
+       if(arity <= 1)
+               return 0;
+
+       for(i = 0; i < arity; ++i) {
+               if(get_Block_cfgpred_block(succ_block, i) == block)
+                       break;
+       }
+       assert(i < arity);
+
+       sched_foreach(succ_block, node) {
+               ir_node *arg;
+
+               if(!is_Phi(node))
+                       break;
+
+               arg = get_irn_n(node, i);
+               if(arg == def)
+                       return 1;
+       }
+
+       return 0;
+}
 
-  return u->next_use;
+static INLINE
+unsigned get_step(const ir_node *node)
+{
+       return PTR_TO_INT(get_irn_link(node));
 }
 
-static unsigned get_next_use(be_uses_t *uses, const ir_node *from, unsigned from_step, const ir_node *def, int skip_from_uses, unsigned long visited_nr)
+static be_next_use_t get_next_use(be_uses_t *env, ir_node *from,
+                                                                 unsigned from_step, const ir_node *def,
+                                                                 int skip_from_uses)
 {
-       unsigned next_use = USES_INFINITY;
-       unsigned step     = from_step;
-       unsigned n        = 0;
-       ir_node *bl       = get_nodes_block(from);
-       const ir_node *irn;
-       const ir_edge_t *succ_edge;
+       unsigned  step  = from_step;
+       ir_node  *block = get_nodes_block(from);
+       ir_node  *next_use;
+       ir_node  *node;
+       unsigned  timestep;
+       unsigned  next_use_step;
+       const ir_edge_t *edge;
+
+#if 1
+       assert(skip_from_uses == 0 || skip_from_uses == 1);
+       if(skip_from_uses) {
+               from = sched_next(from);
+       }
+
+       next_use      = NULL;
+       next_use_step = INT_MAX;
+       timestep      = get_step(from);
+       foreach_out_edge(def, edge) {
+               ir_node  *node = get_edge_src_irn(edge);
+               unsigned  node_step;
+
+               if(is_Anchor(node))
+                       continue;
+               if(get_nodes_block(node) != block)
+                       continue;
+               if(is_Phi(node))
+                       continue;
+
+               node_step = get_step(node);
+               if(node_step < timestep)
+                       continue;
+               if(node_step < next_use_step) {
+                       next_use      = node;
+                       next_use_step = node_step;
+               }
+       }
+
+       if(next_use != NULL) {
+               be_next_use_t result;
+               result.time           = next_use_step - timestep + skip_from_uses;
+               result.outermost_loop = get_loop_depth(get_irn_loop(block));
+               result.before         = next_use;
+               return result;
+       }
+
+       node = sched_last(block);
+       step = get_step(node) + 1 + timestep + skip_from_uses;
+
+#else
+       if(skip_from_uses) {
+               from = sched_next(from);
+               ++step;
+       }
+
+       sched_foreach_from(from, node) {
+               int i, arity;
 
-       set_irn_visited(bl, visited_nr);
+               if(is_Phi(node)) {
+                       step++;
+                       continue;
+               }
+
+               arity = get_irn_arity(node);
+               for (i = 0; i < arity; ++i) {
+                       const ir_node *operand = get_irn_n(node, i);
 
-       sched_foreach_from(from, irn) {
-               int i, n;
+                       if (operand == def) {
+                               be_next_use_t result;
 
-               if (! skip_from_uses) {
-                       for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
-                               ir_node *operand = get_irn_n(irn, i);
+                               DBG((env->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, node));
 
-                               if (operand == def) {
-                                       DBG((uses->dbg, LEVEL_3, "found use of %+F at %+F\n", operand, irn));
-                                       return step;
+                               /**
+                                * Spills/Reloads are a special case, they're not really a
+                                * usage of a value, continue searching
+                                */
+                               if (be_is_Spill(node) || be_is_Reload(node)) {
+                                       return be_get_next_use(env, node, step, node, 1);
                                }
+
+                               result.time           = step;
+                               result.outermost_loop = get_loop_depth(get_irn_loop(block));
+                               result.before         = node;
+                               return result;
                        }
                }
 
-               skip_from_uses = 0;
                step++;
        }
+#endif
+
+       if(be_is_phi_argument(block, def)) {
+               // TODO we really should continue searching the uses of the phi,
+               // as a phi isn't a real use that implies a reload (because we could
+               // easily spill the whole phi)
+
+               be_next_use_t result;
+               result.time           = step;
+               result.outermost_loop = get_loop_depth(get_irn_loop(block));
+               result.before         = block;
+               return result;
+       }
+
+#ifdef SCAN_INTERBLOCK_USES
+       {
+       unsigned next_use   = USES_INFINITY;
+       int outermost_loop;
+       be_next_use_t result;
+       ir_loop *loop       = get_irn_loop(block);
+       int loopdepth       = get_loop_depth(loop);
+       int found_visited   = 0;
+       int found_use       = 0;
+       ir_graph *irg       = get_irn_irg(block);
+       ir_node *startblock = get_irg_start_block(irg);
+
+       result.before  = NULL;
+       outermost_loop = loopdepth;
+       foreach_block_succ(block, edge) {
+               const be_use_t *use;
+               const ir_node *succ_block = get_edge_src_irn(edge);
+               ir_loop *succ_loop;
+               unsigned use_dist;
+
+               if(succ_block == startblock)
+                       continue;
+
+               DBG((env->dbg, LEVEL_5, "Checking succ of block %+F: %+F (for use of %+F)\n", block, succ_block, def));
+               if(!be_is_live_in(env->lv, succ_block, def)) {
+                       //next_use = USES_INFINITY;
+                       DBG((env->dbg, LEVEL_5, "   not live in\n"));
+                       continue;
+               }
+
+               use = get_or_set_use_block(env, succ_block, def);
+               DBG((env->dbg, LEVEL_5, "Found %u (loopdepth %d) (we're in block %+F)\n", use->next_use,
+                                       use->outermost_loop, block));
+               if(USES_IS_INFINITE(use->next_use)) {
+                       if(use->outermost_loop < 0) {
+                               found_visited = 1;
+                       }
+                       continue;
+               }
 
-       /* FIXME: quick and dirty hack to prevent ignore nodes (like stack pointer) from being spilled */
-       return be_is_live_end(uses->lv, bl, def) ? step : USES_INFINITY;
+               found_use = 1;
+               use_dist = use->next_use;
 
-       next_use = USES_INFINITY;
-       foreach_block_succ(bl, succ_edge) {
-               const ir_node *succ_bl = succ_edge->src;
-               if(get_irn_visited(succ_bl) < visited_nr && (be_is_live_in(uses->lv, succ_bl, def) || (get_irn_arity(succ_bl) > 1 && be_is_live_end(uses->lv, bl, def)))) {
-                       unsigned next = get_next_use_bl(uses, succ_bl, def);
+               succ_loop = get_irn_loop(succ_block);
+               if(get_loop_depth(succ_loop) < loopdepth) {
+                       unsigned factor = (loopdepth - get_loop_depth(succ_loop)) * 5000;
+                       DBG((env->dbg, LEVEL_5, "Increase usestep because of loop out edge %d -> %d (%u)\n", factor));
+                       // TODO we should use the number of nodes in the loop or so...
+                       use_dist += factor;
+               }
 
-                       DBG((uses->dbg, LEVEL_2, "\t\tnext use in succ %+F: %d\n", succ_bl, next));
-                       next_use = MIN(next_use, next);
-                       n++;
+               if(use_dist < next_use) {
+                       next_use       = use_dist;
+                       outermost_loop = use->outermost_loop;
+                       result.before  = use->node;
                }
        }
 
-       return next_use + step;
+       if(loopdepth < outermost_loop)
+               outermost_loop = loopdepth;
+
+       result.time           = next_use + step;
+       result.outermost_loop = outermost_loop;
+
+       if(!found_use && found_visited) {
+               // the current result is correct for the current search, but isn't
+               // generally correct, so mark it
+               result.outermost_loop = -1;
+       }
+       DBG((env->dbg, LEVEL_5, "Result: %d (outerloop: %d)\n", result.time, result.outermost_loop));
+       return result;
+       }
+#else
+       return USES_INFINITY;
+#endif
 }
 
-unsigned be_get_next_use(be_uses_t *uses, const ir_node *from, unsigned from_step, const ir_node *def, int skip_from_uses)
+be_next_use_t be_get_next_use(be_uses_t *env, ir_node *from,
+                         unsigned from_step, const ir_node *def,
+                         int skip_from_uses)
 {
-       unsigned long visited_nr = get_irg_visited(uses->irg) + 1;
-
-       set_irg_visited(uses->irg, visited_nr);
-       return get_next_use(uses, from, from_step, def, skip_from_uses, visited_nr);
+       env->visited_counter++;
+       return get_next_use(env, from, from_step, def, skip_from_uses);
 }
 
+static
+void set_sched_step_walker(ir_node *block, void *data)
+{
+       ir_node  *node;
+       unsigned step = 0;
+       (void) data;
+
+       sched_foreach(block, node) {
+               set_irn_link(node, INT_TO_PTR(step));
+               if(is_Phi(node))
+                       continue;
+               if(is_Proj(node))
+                       continue;
+               ++step;
+       }
+}
 
-be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv, const arch_env_t *arch_env, const arch_register_class_t *cls)
+be_uses_t *be_begin_uses(ir_graph *irg, const be_lv_t *lv)
 {
-  be_uses_t *uses = xmalloc(sizeof(uses[0]));
+       be_uses_t *env = xmalloc(sizeof(env[0]));
 
-  edges_assure(irg);
+       edges_assure(irg);
 
-  uses->arch_env = arch_env;
-  uses->uses     = new_set(cmp_use, 512);
-  uses->irg      = irg;
-  uses->lv       = lv;
-  FIRM_DBG_REGISTER(uses->dbg, "firm.be.uses");
+       //set_using_irn_link(irg);
 
-  return uses;
-}
+       /* precalculate sched steps */
+       irg_block_walk_graph(irg, set_sched_step_walker, NULL, NULL);
 
-void be_end_uses(be_uses_t *uses)
-{
-  del_set(uses->uses);
-  free(uses);
+       env->uses = new_set(cmp_use, 512);
+       env->irg = irg;
+       env->lv = lv;
+       env->visited_counter = 0;
+       FIRM_DBG_REGISTER(env->dbg, "firm.be.uses");
+
+       return env;
 }
 
-int loc_compare(const void *a, const void *b)
+void be_end_uses(be_uses_t *env)
 {
-  const loc_t *p = a;
-  const loc_t *q = b;
-  return p->time - q->time;
+       //clear_using_irn_link(env->irg);
+       del_set(env->uses);
+       free(env);
 }