--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/tracer.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,400 @@
+/* The tracer pass for the GNU compiler.
+   Contributed by Jan Hubicka, SuSE Labs.
+   Adapted to work on GIMPLE instead of RTL by Robert Kidd, UIUC.
+   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   Free Software Foundation, Inc.
+
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+/* This pass performs the tail duplication needed for superblock formation.
+   For more information see:
+
+     Design and Analysis of Profile-Based Optimization in Compaq's
+     Compilation Tools for Alpha; Journal of Instruction-Level
+     Parallelism 3 (2000) 1-25
+
+   Unlike Compaq's implementation we don't do the loop peeling as most
+   probably a better job can be done by a special pass and we don't
+   need to worry too much about the code size implications as the tail
+   duplicates are crossjumped again if optimizations are not
+   performed.  */
+
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "rtl.h"
+#include "hard-reg-set.h"
+#include "basic-block.h"
+#include "output.h"
+#include "cfglayout.h"
+#include "fibheap.h"
+#include "flags.h"
+#include "timevar.h"
+#include "params.h"
+#include "coverage.h"
+#include "tree-pass.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+
+static int count_insns (basic_block);
+static bool ignore_bb_p (const_basic_block);
+static bool better_p (const_edge, const_edge);
+static edge find_best_successor (basic_block);
+static edge find_best_predecessor (basic_block);
+static int find_trace (basic_block, basic_block *);
+static void tail_duplicate (void);
+
+/* Minimal outgoing edge probability considered for superblock formation.  */
+static int probability_cutoff;
+static int branch_ratio_cutoff;
+
+/* A bit BB->index is set if BB has already been seen, i.e. it is
+   connected to some trace already.  */
+sbitmap bb_seen;
+
+static inline void
+mark_bb_seen (basic_block bb)
+{
+  unsigned int size = SBITMAP_SIZE_BYTES (bb_seen) * 8;
+
+  if ((unsigned int)bb->index >= size)
+    bb_seen = sbitmap_resize (bb_seen, size * 2, 0);
+
+  SET_BIT (bb_seen, bb->index);
+}
+
+static inline bool
+bb_seen_p (basic_block bb)
+{
+  return TEST_BIT (bb_seen, bb->index);
+}
+
+/* Return true if we should ignore the basic block for purposes of tracing.  */
+static bool
+ignore_bb_p (const_basic_block bb)
+{
+  if (bb->index < NUM_FIXED_BLOCKS)
+    return true;
+  if (optimize_bb_for_size_p (bb))
+    return true;
+  return false;
+}
+
+/* Return number of instructions in the block.  */
+
+static int
+count_insns (basic_block bb)
+{
+  gimple_stmt_iterator gsi;
+  gimple stmt;
+  int n = 0;
+
+  for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      stmt = gsi_stmt (gsi);
+      n += estimate_num_insns (stmt, &eni_size_weights);
+    }
+  return n;
+}
+
+/* Return true if E1 is more frequent than E2.  */
+static bool
+better_p (const_edge e1, const_edge e2)
+{
+  if (e1->count != e2->count)
+    return e1->count > e2->count;
+  if (e1->src->frequency * e1->probability !=
+      e2->src->frequency * e2->probability)
+    return (e1->src->frequency * e1->probability
+	    > e2->src->frequency * e2->probability);
+  /* This is needed to avoid changes in the decision after
+     CFG is modified.  */
+  if (e1->src != e2->src)
+    return e1->src->index > e2->src->index;
+  return e1->dest->index > e2->dest->index;
+}
+
+/* Return most frequent successor of basic block BB.  */
+
+static edge
+find_best_successor (basic_block bb)
+{
+  edge e;
+  edge best = NULL;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, bb->succs)
+    if (!best || better_p (e, best))
+      best = e;
+  if (!best || ignore_bb_p (best->dest))
+    return NULL;
+  if (best->probability <= probability_cutoff)
+    return NULL;
+  return best;
+}
+
+/* Return most frequent predecessor of basic block BB.  */
+
+static edge
+find_best_predecessor (basic_block bb)
+{
+  edge e;
+  edge best = NULL;
+  edge_iterator ei;
+
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    if (!best || better_p (e, best))
+      best = e;
+  if (!best || ignore_bb_p (best->src))
+    return NULL;
+  if (EDGE_FREQUENCY (best) * REG_BR_PROB_BASE
+      < bb->frequency * branch_ratio_cutoff)
+    return NULL;
+  return best;
+}
+
+/* Find the trace using bb and record it in the TRACE array.
+   Return number of basic blocks recorded.  */
+
+static int
+find_trace (basic_block bb, basic_block *trace)
+{
+  int i = 0;
+  edge e;
+
+  if (dump_file)
+    fprintf (dump_file, "Trace seed %i [%i]", bb->index, bb->frequency);
+
+  while ((e = find_best_predecessor (bb)) != NULL)
+    {
+      basic_block bb2 = e->src;
+      if (bb_seen_p (bb2) || (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
+	  || find_best_successor (bb2) != e)
+	break;
+      if (dump_file)
+	fprintf (dump_file, ",%i [%i]", bb->index, bb->frequency);
+      bb = bb2;
+    }
+  if (dump_file)
+    fprintf (dump_file, " forward %i [%i]", bb->index, bb->frequency);
+  trace[i++] = bb;
+
+  /* Follow the trace in forward direction.  */
+  while ((e = find_best_successor (bb)) != NULL)
+    {
+      bb = e->dest;
+      if (bb_seen_p (bb) || (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX))
+	  || find_best_predecessor (bb) != e)
+	break;
+      if (dump_file)
+	fprintf (dump_file, ",%i [%i]", bb->index, bb->frequency);
+      trace[i++] = bb;
+    }
+  if (dump_file)
+    fprintf (dump_file, "\n");
+  return i;
+}
+
+/* Look for basic blocks in frequency order, construct traces and tail duplicate
+   if profitable.  */
+
+static void
+tail_duplicate (void)
+{
+  fibnode_t *blocks = XCNEWVEC (fibnode_t, last_basic_block);
+  basic_block *trace = XNEWVEC (basic_block, n_basic_blocks);
+  int *counts = XNEWVEC (int, last_basic_block);
+  int ninsns = 0, nduplicated = 0;
+  gcov_type weighted_insns = 0, traced_insns = 0;
+  fibheap_t heap = fibheap_new ();
+  gcov_type cover_insns;
+  int max_dup_insns;
+  basic_block bb;
+
+  /* Create an oversized sbitmap to reduce the chance that we need to
+     resize it.  */
+  bb_seen = sbitmap_alloc (last_basic_block * 2);
+  sbitmap_zero (bb_seen);
+  initialize_original_copy_tables ();
+
+  if (profile_info && flag_branch_probabilities)
+    probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK);
+  else
+    probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY);
+  probability_cutoff = REG_BR_PROB_BASE / 100 * probability_cutoff;
+
+  branch_ratio_cutoff =
+    (REG_BR_PROB_BASE / 100 * PARAM_VALUE (TRACER_MIN_BRANCH_RATIO));
+
+  FOR_EACH_BB (bb)
+    {
+      int n = count_insns (bb);
+      if (!ignore_bb_p (bb))
+	blocks[bb->index] = fibheap_insert (heap, -bb->frequency,
+					    bb);
+
+      counts [bb->index] = n;
+      ninsns += n;
+      weighted_insns += n * bb->frequency;
+    }
+
+  if (profile_info && flag_branch_probabilities)
+    cover_insns = PARAM_VALUE (TRACER_DYNAMIC_COVERAGE_FEEDBACK);
+  else
+    cover_insns = PARAM_VALUE (TRACER_DYNAMIC_COVERAGE);
+  cover_insns = (weighted_insns * cover_insns + 50) / 100;
+  max_dup_insns = (ninsns * PARAM_VALUE (TRACER_MAX_CODE_GROWTH) + 50) / 100;
+
+  while (traced_insns < cover_insns && nduplicated < max_dup_insns
+         && !fibheap_empty (heap))
+    {
+      basic_block bb = (basic_block) fibheap_extract_min (heap);
+      int n, pos;
+
+      if (!bb)
+	break;
+
+      blocks[bb->index] = NULL;
+
+      if (ignore_bb_p (bb))
+	continue;
+      gcc_assert (!bb_seen_p (bb));
+
+      n = find_trace (bb, trace);
+
+      bb = trace[0];
+      traced_insns += bb->frequency * counts [bb->index];
+      if (blocks[bb->index])
+	{
+	  fibheap_delete_node (heap, blocks[bb->index]);
+	  blocks[bb->index] = NULL;
+	}
+
+      for (pos = 1; pos < n; pos++)
+	{
+	  basic_block bb2 = trace[pos];
+
+	  if (blocks[bb2->index])
+	    {
+	      fibheap_delete_node (heap, blocks[bb2->index]);
+	      blocks[bb2->index] = NULL;
+	    }
+	  traced_insns += bb2->frequency * counts [bb2->index];
+	  if (EDGE_COUNT (bb2->preds) > 1
+	      && can_duplicate_block_p (bb2))
+	    {
+	      edge e;
+	      basic_block copy;
+
+	      nduplicated += counts [bb2->index];
+
+	      e = find_edge (bb, bb2);
+	      
+	      copy = duplicate_block (bb2, e, bb);
+	      flush_pending_stmts (e);
+
+	      add_phi_args_after_copy (&copy, 1, NULL);
+
+	      /* Reconsider the original copy of block we've duplicated.
+	         Removing the most common predecessor may make it to be
+	         head.  */
+	      blocks[bb2->index] =
+		fibheap_insert (heap, -bb2->frequency, bb2);
+
+	      if (dump_file)
+		fprintf (dump_file, "Duplicated %i as %i [%i]\n",
+			 bb2->index, copy->index, copy->frequency);
+
+	      bb2 = copy;
+	    }
+	  mark_bb_seen (bb2);
+	  bb = bb2;
+	  /* In case the trace became infrequent, stop duplicating.  */
+	  if (ignore_bb_p (bb))
+	    break;
+	}
+      if (dump_file)
+	fprintf (dump_file, " covered now %.1f\n\n",
+		 traced_insns * 100.0 / weighted_insns);
+    }
+  if (dump_file)
+    fprintf (dump_file, "Duplicated %i insns (%i%%)\n", nduplicated,
+	     nduplicated * 100 / ninsns);
+
+  free_original_copy_tables ();
+  sbitmap_free (bb_seen);
+  free (blocks);
+  free (trace);
+  free (counts);
+  fibheap_delete (heap);
+}
+
+/* Main entry point to this file.  */
+
+static unsigned int
+tracer (void)
+{
+  gcc_assert (current_ir_type () == IR_GIMPLE);
+
+  if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1)
+    return 0;
+
+  mark_dfs_back_edges ();
+  if (dump_file)
+    dump_flow_info (dump_file, dump_flags);
+
+  /* Trace formation is done on the fly inside tail_duplicate */
+  tail_duplicate ();
+
+  /* FIXME: We really only need to do this when we know tail duplication
+            has altered the CFG. */
+  free_dominance_info (CDI_DOMINATORS);
+  if (dump_file)
+    dump_flow_info (dump_file, dump_flags);
+
+  return 0;
+}
+
+static bool
+gate_tracer (void)
+{
+  return (optimize > 0 && flag_tracer && flag_reorder_blocks);
+}
+
+struct gimple_opt_pass pass_tracer =
+{
+ {
+  GIMPLE_PASS,
+  "tracer",                             /* name */
+  gate_tracer,                          /* gate */
+  tracer,                               /* execute */
+  NULL,                                 /* sub */
+  NULL,                                 /* next */
+  0,                                    /* static_pass_number */
+  TV_TRACER,                            /* tv_id */
+  0,                                    /* properties_required */
+  0,                                    /* properties_provided */
+  0,                                    /* properties_destroyed */
+  0,                                    /* todo_flags_start */
+  TODO_dump_func
+    | TODO_update_ssa
+    | TODO_verify_ssa                   /* todo_flags_finish */
+ }
+};