Initial checkin of GCC 4.9.0 from trunk (r208799).

Change-Id: I48a3c08bb98542aa215912a75f03c0890e497dba

1 files changed, 2294 insertions, 0 deletions

diff --git a/gcc-4.9/gcc/tree-ssa-phiopt.c b/gcc-4.9/gcc/tree-ssa-phiopt.c
new file mode 100644
index 000000000..95cf4d470
--- /dev/null
+++ b/gcc-4.9/gcc/tree-ssa-phiopt.c
@@ -0,0 +1,2294 @@
+/* Optimization of PHI nodes by converting them into straightline code.
+   Copyright (C) 2004-2014 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/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "hash-table.h"
+#include "tm.h"
+#include "tree.h"
+#include "stor-layout.h"
+#include "flags.h"
+#include "tm_p.h"
+#include "basic-block.h"
+#include "pointer-set.h"
+#include "tree-ssa-alias.h"
+#include "internal-fn.h"
+#include "gimple-expr.h"
+#include "is-a.h"
+#include "gimple.h"
+#include "gimplify.h"
+#include "gimple-iterator.h"
+#include "gimplify-me.h"
+#include "gimple-ssa.h"
+#include "tree-cfg.h"
+#include "tree-phinodes.h"
+#include "ssa-iterators.h"
+#include "stringpool.h"
+#include "tree-ssanames.h"
+#include "expr.h"
+#include "tree-dfa.h"
+#include "tree-pass.h"
+#include "langhooks.h"
+#include "domwalk.h"
+#include "cfgloop.h"
+#include "tree-data-ref.h"
+#include "gimple-pretty-print.h"
+#include "insn-config.h"
+#include "expr.h"
+#include "optabs.h"
+#include "tree-scalar-evolution.h"
+
+#ifndef HAVE_conditional_move
+#define HAVE_conditional_move (0)
+#endif
+
+static unsigned int tree_ssa_phiopt (void);
+static unsigned int tree_ssa_phiopt_worker (bool, bool);
+static bool conditional_replacement (basic_block, basic_block,
+				     edge, edge, gimple, tree, tree);
+static int value_replacement (basic_block, basic_block,
+			      edge, edge, gimple, tree, tree);
+static bool minmax_replacement (basic_block, basic_block,
+				edge, edge, gimple, tree, tree);
+static bool abs_replacement (basic_block, basic_block,
+			     edge, edge, gimple, tree, tree);
+static bool neg_replacement (basic_block, basic_block,
+			     edge, edge, gimple, tree, tree);
+static bool cond_store_replacement (basic_block, basic_block, edge, edge,
+				    struct pointer_set_t *);
+static bool cond_if_else_store_replacement (basic_block, basic_block, basic_block);
+static struct pointer_set_t * get_non_trapping (void);
+static void replace_phi_edge_with_variable (basic_block, edge, gimple, tree);
+static void hoist_adjacent_loads (basic_block, basic_block,
+				  basic_block, basic_block);
+static bool gate_hoist_loads (void);
+
+/* This pass tries to replaces an if-then-else block with an
+   assignment.  We have four kinds of transformations.  Some of these
+   transformations are also performed by the ifcvt RTL optimizer.
+
+   Conditional Replacement
+   -----------------------
+
+   This transformation, implemented in conditional_replacement,
+   replaces
+
+     bb0:
+      if (cond) goto bb2; else goto bb1;
+     bb1:
+     bb2:
+      x = PHI <0 (bb1), 1 (bb0), ...>;
+
+   with
+
+     bb0:
+      x' = cond;
+      goto bb2;
+     bb2:
+      x = PHI <x' (bb0), ...>;
+
+   We remove bb1 as it becomes unreachable.  This occurs often due to
+   gimplification of conditionals.
+
+   Value Replacement
+   -----------------
+
+   This transformation, implemented in value_replacement, replaces
+
+     bb0:
+       if (a != b) goto bb2; else goto bb1;
+     bb1:
+     bb2:
+       x = PHI <a (bb1), b (bb0), ...>;
+
+   with
+
+     bb0:
+     bb2:
+       x = PHI <b (bb0), ...>;
+
+   This opportunity can sometimes occur as a result of other
+   optimizations.
+
+
+   Another case caught by value replacement looks like this:
+
+     bb0:
+       t1 = a == CONST;
+       t2 = b > c;
+       t3 = t1 & t2;
+       if (t3 != 0) goto bb1; else goto bb2;
+     bb1:
+     bb2:
+       x = PHI (CONST, a)
+
+   Gets replaced with:
+     bb0:
+     bb2:
+       t1 = a == CONST;
+       t2 = b > c;
+       t3 = t1 & t2;
+       x = a;
+
+   ABS Replacement
+   ---------------
+
+   This transformation, implemented in abs_replacement, replaces
+
+     bb0:
+       if (a >= 0) goto bb2; else goto bb1;
+     bb1:
+       x = -a;
+     bb2:
+       x = PHI <x (bb1), a (bb0), ...>;
+
+   with
+
+     bb0:
+       x' = ABS_EXPR< a >;
+     bb2:
+       x = PHI <x' (bb0), ...>;
+
+   MIN/MAX Replacement
+   -------------------
+
+   This transformation, minmax_replacement replaces
+
+     bb0:
+       if (a <= b) goto bb2; else goto bb1;
+     bb1:
+     bb2:
+       x = PHI <b (bb1), a (bb0), ...>;
+
+   with
+
+     bb0:
+       x' = MIN_EXPR (a, b)
+     bb2:
+       x = PHI <x' (bb0), ...>;
+
+   A similar transformation is done for MAX_EXPR.
+
+
+   This pass also performs a fifth transformation of a slightly different
+   flavor.
+
+   Adjacent Load Hoisting
+   ----------------------
+
+   This transformation replaces
+
+     bb0:
+       if (...) goto bb2; else goto bb1;
+     bb1:
+       x1 = (<expr>).field1;
+       goto bb3;
+     bb2:
+       x2 = (<expr>).field2;
+     bb3:
+       # x = PHI <x1, x2>;
+
+   with
+
+     bb0:
+       x1 = (<expr>).field1;
+       x2 = (<expr>).field2;
+       if (...) goto bb2; else goto bb1;
+     bb1:
+       goto bb3;
+     bb2:
+     bb3:
+       # x = PHI <x1, x2>;
+
+   The purpose of this transformation is to enable generation of conditional
+   move instructions such as Intel CMOVE or PowerPC ISEL.  Because one of
+   the loads is speculative, the transformation is restricted to very
+   specific cases to avoid introducing a page fault.  We are looking for
+   the common idiom:
+
+     if (...)
+       x = y->left;
+     else
+       x = y->right;
+
+   where left and right are typically adjacent pointers in a tree structure.  */
+
+static unsigned int
+tree_ssa_phiopt (void)
+{
+  return tree_ssa_phiopt_worker (false, gate_hoist_loads ());
+}
+
+/* This pass tries to transform conditional stores into unconditional
+   ones, enabling further simplifications with the simpler then and else
+   blocks.  In particular it replaces this:
+
+     bb0:
+       if (cond) goto bb2; else goto bb1;
+     bb1:
+       *p = RHS;
+     bb2:
+
+   with
+
+     bb0:
+       if (cond) goto bb1; else goto bb2;
+     bb1:
+       condtmp' = *p;
+     bb2:
+       condtmp = PHI <RHS, condtmp'>
+       *p = condtmp;
+
+   This transformation can only be done under several constraints,
+   documented below.  It also replaces:
+
+     bb0:
+       if (cond) goto bb2; else goto bb1;
+     bb1:
+       *p = RHS1;
+       goto bb3;
+     bb2:
+       *p = RHS2;
+     bb3:
+
+   with
+
+     bb0:
+       if (cond) goto bb3; else goto bb1;
+     bb1:
+     bb3:
+       condtmp = PHI <RHS1, RHS2>
+       *p = condtmp;  */
+
+static unsigned int
+tree_ssa_cs_elim (void)
+{
+  unsigned todo;
+  /* ???  We are not interested in loop related info, but the following
+     will create it, ICEing as we didn't init loops with pre-headers.
+     An interfacing issue of find_data_references_in_bb.  */
+  loop_optimizer_init (LOOPS_NORMAL);
+  scev_initialize ();
+  todo = tree_ssa_phiopt_worker (true, false);
+  scev_finalize ();
+  loop_optimizer_finalize ();
+  return todo;
+}
+
+/* Return the singleton PHI in the SEQ of PHIs for edges E0 and E1. */
+
+static gimple
+single_non_singleton_phi_for_edges (gimple_seq seq, edge e0, edge e1)
+{
+  gimple_stmt_iterator i;
+  gimple phi = NULL;
+  if (gimple_seq_singleton_p (seq))
+    return gsi_stmt (gsi_start (seq));
+  for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
+    {
+      gimple p = gsi_stmt (i);
+      /* If the PHI arguments are equal then we can skip this PHI. */
+      if (operand_equal_for_phi_arg_p (gimple_phi_arg_def (p, e0->dest_idx),
+				       gimple_phi_arg_def (p, e1->dest_idx)))
+	continue;
+
+      /* If we already have a PHI that has the two edge arguments are
+	 different, then return it is not a singleton for these PHIs. */
+      if (phi)
+	return NULL;
+
+      phi = p;
+    }
+  return phi;
+}
+
+/* The core routine of conditional store replacement and normal
+   phi optimizations.  Both share much of the infrastructure in how
+   to match applicable basic block patterns.  DO_STORE_ELIM is true
+   when we want to do conditional store replacement, false otherwise.
+   DO_HOIST_LOADS is true when we want to hoist adjacent loads out
+   of diamond control flow patterns, false otherwise.  */
+static unsigned int
+tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads)
+{
+  basic_block bb;
+  basic_block *bb_order;
+  unsigned n, i;
+  bool cfgchanged = false;
+  struct pointer_set_t *nontrap = 0;
+
+  if (do_store_elim)
+    /* Calculate the set of non-trapping memory accesses.  */
+    nontrap = get_non_trapping ();
+
+  /* The replacement of conditional negation with a non-branching
+     sequence is really only a win when optimizing for speed and we
+     can avoid transformations by gimple if-conversion that result
+     in poor RTL generation.
+
+     Ideally either gimple if-conversion or the RTL expanders will
+     be improved and the code to emit branchless conditional negation
+     can be removed.  */
+  bool replace_conditional_negation = false;
+  if (!do_store_elim)
+    replace_conditional_negation
+      = ((!optimize_size && optimize >= 2)
+	 || (((flag_tree_loop_vectorize || cfun->has_force_vect_loops)
+	      && flag_tree_loop_if_convert != 0)
+	     || flag_tree_loop_if_convert == 1
+	     || flag_tree_loop_if_convert_stores == 1));
+
+  /* Search every basic block for COND_EXPR we may be able to optimize.
+
+     We walk the blocks in order that guarantees that a block with
+     a single predecessor is processed before the predecessor.
+     This ensures that we collapse inner ifs before visiting the
+     outer ones, and also that we do not try to visit a removed
+     block.  */
+  bb_order = single_pred_before_succ_order ();
+  n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS;
+
+  for (i = 0; i < n; i++)
+    {
+      gimple cond_stmt, phi;
+      basic_block bb1, bb2;
+      edge e1, e2;
+      tree arg0, arg1;
+
+      bb = bb_order[i];
+
+      cond_stmt = last_stmt (bb);
+      /* Check to see if the last statement is a GIMPLE_COND.  */
+      if (!cond_stmt
+          || gimple_code (cond_stmt) != GIMPLE_COND)
+        continue;
+
+      e1 = EDGE_SUCC (bb, 0);
+      bb1 = e1->dest;
+      e2 = EDGE_SUCC (bb, 1);
+      bb2 = e2->dest;
+
+      /* We cannot do the optimization on abnormal edges.  */
+      if ((e1->flags & EDGE_ABNORMAL) != 0
+          || (e2->flags & EDGE_ABNORMAL) != 0)
+       continue;
+
+      /* If either bb1's succ or bb2 or bb2's succ is non NULL.  */
+      if (EDGE_COUNT (bb1->succs) == 0
+          || bb2 == NULL
+	  || EDGE_COUNT (bb2->succs) == 0)
+        continue;
+
+      /* Find the bb which is the fall through to the other.  */
+      if (EDGE_SUCC (bb1, 0)->dest == bb2)
+        ;
+      else if (EDGE_SUCC (bb2, 0)->dest == bb1)
+        {
+	  basic_block bb_tmp = bb1;
+	  edge e_tmp = e1;
+	  bb1 = bb2;
+	  bb2 = bb_tmp;
+	  e1 = e2;
+	  e2 = e_tmp;
+	}
+      else if (do_store_elim
+	       && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
+	{
+	  basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
+
+	  if (!single_succ_p (bb1)
+	      || (EDGE_SUCC (bb1, 0)->flags & EDGE_FALLTHRU) == 0
+	      || !single_succ_p (bb2)
+	      || (EDGE_SUCC (bb2, 0)->flags & EDGE_FALLTHRU) == 0
+	      || EDGE_COUNT (bb3->preds) != 2)
+	    continue;
+	  if (cond_if_else_store_replacement (bb1, bb2, bb3))
+	    cfgchanged = true;
+	  continue;
+	}
+      else if (do_hoist_loads
+		 && EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
+	{
+	  basic_block bb3 = EDGE_SUCC (bb1, 0)->dest;
+
+	  if (!FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (cond_stmt)))
+	      && single_succ_p (bb1)
+	      && single_succ_p (bb2)
+	      && single_pred_p (bb1)
+	      && single_pred_p (bb2)
+	      && EDGE_COUNT (bb->succs) == 2
+	      && EDGE_COUNT (bb3->preds) == 2
+	      /* If one edge or the other is dominant, a conditional move
+		 is likely to perform worse than the well-predicted branch.  */
+	      && !predictable_edge_p (EDGE_SUCC (bb, 0))
+	      && !predictable_edge_p (EDGE_SUCC (bb, 1)))
+	    hoist_adjacent_loads (bb, bb1, bb2, bb3);
+	  continue;
+	}
+      else
+	continue;
+
+      e1 = EDGE_SUCC (bb1, 0);
+
+      /* Make sure that bb1 is just a fall through.  */
+      if (!single_succ_p (bb1)
+	  || (e1->flags & EDGE_FALLTHRU) == 0)
+        continue;
+
+      /* Also make sure that bb1 only have one predecessor and that it
+	 is bb.  */
+      if (!single_pred_p (bb1)
+          || single_pred (bb1) != bb)
+	continue;
+
+      if (do_store_elim)
+	{
+	  /* bb1 is the middle block, bb2 the join block, bb the split block,
+	     e1 the fallthrough edge from bb1 to bb2.  We can't do the
+	     optimization if the join block has more than two predecessors.  */
+	  if (EDGE_COUNT (bb2->preds) > 2)
+	    continue;
+	  if (cond_store_replacement (bb1, bb2, e1, e2, nontrap))
+	    cfgchanged = true;
+	}
+      else
+	{
+	  gimple_seq phis = phi_nodes (bb2);
+	  gimple_stmt_iterator gsi;
+	  bool candorest = true;
+
+	  /* Value replacement can work with more than one PHI
+	     so try that first. */
+	  for (gsi = gsi_start (phis); !gsi_end_p (gsi); gsi_next (&gsi))
+	    {
+	      phi = gsi_stmt (gsi);
+	      arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
+	      arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
+	      if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1) == 2)
+		{
+		  candorest = false;
+	          cfgchanged = true;
+		  break;
+		}
+	    }
+
+	  if (!candorest)
+	    continue;
+
+	  phi = single_non_singleton_phi_for_edges (phis, e1, e2);
+	  if (!phi)
+	    continue;
+
+	  arg0 = gimple_phi_arg_def (phi, e1->dest_idx);
+	  arg1 = gimple_phi_arg_def (phi, e2->dest_idx);
+
+	  /* Something is wrong if we cannot find the arguments in the PHI
+	     node.  */
+	  gcc_assert (arg0 != NULL && arg1 != NULL);
+
+	  /* Do the replacement of conditional if it can be done.  */
+	  if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+	    cfgchanged = true;
+	  else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+	    cfgchanged = true;
+	  else if (replace_conditional_negation
+		   && neg_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+	    cfgchanged = true;
+	  else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
+	    cfgchanged = true;
+	}
+    }
+
+  free (bb_order);
+
+  if (do_store_elim)
+    pointer_set_destroy (nontrap);
+  /* If the CFG has changed, we should cleanup the CFG.  */
+  if (cfgchanged && do_store_elim)
+    {
+      /* In cond-store replacement we have added some loads on edges
+         and new VOPS (as we moved the store, and created a load).  */
+      gsi_commit_edge_inserts ();
+      return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
+    }
+  else if (cfgchanged)
+    return TODO_cleanup_cfg;
+  return 0;
+}
+
+/* Replace PHI node element whose edge is E in block BB with variable NEW.
+   Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK
+   is known to have two edges, one of which must reach BB).  */
+
+static void
+replace_phi_edge_with_variable (basic_block cond_block,
+				edge e, gimple phi, tree new_tree)
+{
+  basic_block bb = gimple_bb (phi);
+  basic_block block_to_remove;
+  gimple_stmt_iterator gsi;
+
+  /* Change the PHI argument to new.  */
+  SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree);
+
+  /* Remove the empty basic block.  */
+  if (EDGE_SUCC (cond_block, 0)->dest == bb)
+    {
+      EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU;
+      EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+      EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE;
+      EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count;
+
+      block_to_remove = EDGE_SUCC (cond_block, 1)->dest;
+    }
+  else
+    {
+      EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU;
+      EDGE_SUCC (cond_block, 1)->flags
+	&= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+      EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE;
+      EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count;
+
+      block_to_remove = EDGE_SUCC (cond_block, 0)->dest;
+    }
+  delete_basic_block (block_to_remove);
+
+  /* Eliminate the COND_EXPR at the end of COND_BLOCK.  */
+  gsi = gsi_last_bb (cond_block);
+  gsi_remove (&gsi, true);
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    fprintf (dump_file,
+	      "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
+	      cond_block->index,
+	      bb->index);
+}
+
+/*  The function conditional_replacement does the main work of doing the
+    conditional replacement.  Return true if the replacement is done.
+    Otherwise return false.
+    BB is the basic block where the replacement is going to be done on.  ARG0
+    is argument 0 from PHI.  Likewise for ARG1.  */
+
+static bool
+conditional_replacement (basic_block cond_bb, basic_block middle_bb,
+			 edge e0, edge e1, gimple phi,
+			 tree arg0, tree arg1)
+{
+  tree result;
+  gimple stmt, new_stmt;
+  tree cond;
+  gimple_stmt_iterator gsi;
+  edge true_edge, false_edge;
+  tree new_var, new_var2;
+  bool neg;
+
+  /* FIXME: Gimplification of complex type is too hard for now.  */
+  /* We aren't prepared to handle vectors either (and it is a question
+     if it would be worthwhile anyway).  */
+  if (!(INTEGRAL_TYPE_P (TREE_TYPE (arg0))
+	|| POINTER_TYPE_P (TREE_TYPE (arg0)))
+      || !(INTEGRAL_TYPE_P (TREE_TYPE (arg1))
+	   || POINTER_TYPE_P (TREE_TYPE (arg1))))
+    return false;
+
+  /* The PHI arguments have the constants 0 and 1, or 0 and -1, then
+     convert it to the conditional.  */
+  if ((integer_zerop (arg0) && integer_onep (arg1))
+      || (integer_zerop (arg1) && integer_onep (arg0)))
+    neg = false;
+  else if ((integer_zerop (arg0) && integer_all_onesp (arg1))
+	   || (integer_zerop (arg1) && integer_all_onesp (arg0)))
+    neg = true;
+  else
+    return false;
+
+  if (!empty_block_p (middle_bb))
+    return false;
+
+  /* At this point we know we have a GIMPLE_COND with two successors.
+     One successor is BB, the other successor is an empty block which
+     falls through into BB.
+
+     There is a single PHI node at the join point (BB) and its arguments
+     are constants (0, 1) or (0, -1).
+
+     So, given the condition COND, and the two PHI arguments, we can
+     rewrite this PHI into non-branching code:
+
+       dest = (COND) or dest = COND'
+
+     We use the condition as-is if the argument associated with the
+     true edge has the value one or the argument associated with the
+     false edge as the value zero.  Note that those conditions are not
+     the same since only one of the outgoing edges from the GIMPLE_COND
+     will directly reach BB and thus be associated with an argument.  */
+
+  stmt = last_stmt (cond_bb);
+  result = PHI_RESULT (phi);
+
+  /* To handle special cases like floating point comparison, it is easier and
+     less error-prone to build a tree and gimplify it on the fly though it is
+     less efficient.  */
+  cond = fold_build2_loc (gimple_location (stmt),
+			  gimple_cond_code (stmt), boolean_type_node,
+			  gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
+
+  /* We need to know which is the true edge and which is the false
+     edge so that we know when to invert the condition below.  */
+  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+  if ((e0 == true_edge && integer_zerop (arg0))
+      || (e0 == false_edge && !integer_zerop (arg0))
+      || (e1 == true_edge && integer_zerop (arg1))
+      || (e1 == false_edge && !integer_zerop (arg1)))
+    cond = fold_build1_loc (gimple_location (stmt),
+                            TRUTH_NOT_EXPR, TREE_TYPE (cond), cond);
+
+  if (neg)
+    {
+      cond = fold_convert_loc (gimple_location (stmt),
+                               TREE_TYPE (result), cond);
+      cond = fold_build1_loc (gimple_location (stmt),
+                              NEGATE_EXPR, TREE_TYPE (cond), cond);
+    }
+
+  /* Insert our new statements at the end of conditional block before the
+     COND_STMT.  */
+  gsi = gsi_for_stmt (stmt);
+  new_var = force_gimple_operand_gsi (&gsi, cond, true, NULL, true,
+				      GSI_SAME_STMT);
+
+  if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (new_var)))
+    {
+      source_location locus_0, locus_1;
+
+      new_var2 = make_ssa_name (TREE_TYPE (result), NULL);
+      new_stmt = gimple_build_assign_with_ops (CONVERT_EXPR, new_var2,
+					       new_var, NULL);
+      gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
+      new_var = new_var2;
+
+      /* Set the locus to the first argument, unless is doesn't have one.  */
+      locus_0 = gimple_phi_arg_location (phi, 0);
+      locus_1 = gimple_phi_arg_location (phi, 1);
+      if (locus_0 == UNKNOWN_LOCATION)
+        locus_0 = locus_1;
+      gimple_set_location (new_stmt, locus_0);
+    }
+
+  replace_phi_edge_with_variable (cond_bb, e1, phi, new_var);
+
+  /* Note that we optimized this PHI.  */
+  return true;
+}
+
+/* Update *ARG which is defined in STMT so that it contains the
+   computed value if that seems profitable.  Return true if the
+   statement is made dead by that rewriting.  */
+
+static bool
+jump_function_from_stmt (tree *arg, gimple stmt)
+{
+  enum tree_code code = gimple_assign_rhs_code (stmt);
+  if (code == ADDR_EXPR)
+    {
+      /* For arg = &p->i transform it to p, if possible.  */
+      tree rhs1 = gimple_assign_rhs1 (stmt);
+      HOST_WIDE_INT offset;
+      tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs1, 0),
+						&offset);
+      if (tem
+	  && TREE_CODE (tem) == MEM_REF
+	  && (mem_ref_offset (tem) + double_int::from_shwi (offset)).is_zero ())
+	{
+	  *arg = TREE_OPERAND (tem, 0);
+	  return true;
+	}
+    }
+  /* TODO: Much like IPA-CP jump-functions we want to handle constant
+     additions symbolically here, and we'd need to update the comparison
+     code that compares the arg + cst tuples in our caller.  For now the
+     code above exactly handles the VEC_BASE pattern from vec.h.  */
+  return false;
+}
+
+/* RHS is a source argument in a BIT_AND_EXPR which feeds a conditional
+   of the form SSA_NAME NE 0.
+
+   If RHS is fed by a simple EQ_EXPR comparison of two values, see if
+   the two input values of the EQ_EXPR match arg0 and arg1.
+
+   If so update *code and return TRUE.  Otherwise return FALSE.  */
+
+static bool
+rhs_is_fed_for_value_replacement (const_tree arg0, const_tree arg1,
+				  enum tree_code *code, const_tree rhs)
+{
+  /* Obviously if RHS is not an SSA_NAME, we can't look at the defining
+     statement.  */
+  if (TREE_CODE (rhs) == SSA_NAME)
+    {
+      gimple def1 = SSA_NAME_DEF_STMT (rhs);
+
+      /* Verify the defining statement has an EQ_EXPR on the RHS.  */
+      if (is_gimple_assign (def1) && gimple_assign_rhs_code (def1) == EQ_EXPR)
+	{
+	  /* Finally verify the source operands of the EQ_EXPR are equal
+	     to arg0 and arg1.  */
+	  tree op0 = gimple_assign_rhs1 (def1);
+	  tree op1 = gimple_assign_rhs2 (def1);
+	  if ((operand_equal_for_phi_arg_p (arg0, op0)
+	       && operand_equal_for_phi_arg_p (arg1, op1))
+	      || (operand_equal_for_phi_arg_p (arg0, op1)
+               && operand_equal_for_phi_arg_p (arg1, op0)))
+	    {
+	      /* We will perform the optimization.  */
+	      *code = gimple_assign_rhs_code (def1);
+	      return true;
+	    }
+	}
+    }
+  return false;
+}
+
+/* Return TRUE if arg0/arg1 are equal to the rhs/lhs or lhs/rhs of COND. 
+
+   Also return TRUE if arg0/arg1 are equal to the source arguments of a
+   an EQ comparison feeding a BIT_AND_EXPR which feeds COND. 
+
+   Return FALSE otherwise.  */
+
+static bool
+operand_equal_for_value_replacement (const_tree arg0, const_tree arg1,
+				     enum tree_code *code, gimple cond)
+{
+  gimple def;
+  tree lhs = gimple_cond_lhs (cond);
+  tree rhs = gimple_cond_rhs (cond);
+
+  if ((operand_equal_for_phi_arg_p (arg0, lhs)
+       && operand_equal_for_phi_arg_p (arg1, rhs))
+      || (operand_equal_for_phi_arg_p (arg1, lhs)
+	  && operand_equal_for_phi_arg_p (arg0, rhs)))
+    return true;
+
+  /* Now handle more complex case where we have an EQ comparison
+     which feeds a BIT_AND_EXPR which feeds COND.
+
+     First verify that COND is of the form SSA_NAME NE 0.  */
+  if (*code != NE_EXPR || !integer_zerop (rhs)
+      || TREE_CODE (lhs) != SSA_NAME)
+    return false;
+
+  /* Now ensure that SSA_NAME is set by a BIT_AND_EXPR.  */
+  def = SSA_NAME_DEF_STMT (lhs);
+  if (!is_gimple_assign (def) || gimple_assign_rhs_code (def) != BIT_AND_EXPR)
+    return false;
+
+  /* Now verify arg0/arg1 correspond to the source arguments of an 
+     EQ comparison feeding the BIT_AND_EXPR.  */
+     
+  tree tmp = gimple_assign_rhs1 (def);
+  if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
+    return true;
+
+  tmp = gimple_assign_rhs2 (def);
+  if (rhs_is_fed_for_value_replacement (arg0, arg1, code, tmp))
+    return true;
+
+  return false;
+}
+
+/*  The function value_replacement does the main work of doing the value
+    replacement.  Return non-zero if the replacement is done.  Otherwise return
+    0.  If we remove the middle basic block, return 2.
+    BB is the basic block where the replacement is going to be done on.  ARG0
+    is argument 0 from the PHI.  Likewise for ARG1.  */
+
+static int
+value_replacement (basic_block cond_bb, basic_block middle_bb,
+		   edge e0, edge e1, gimple phi,
+		   tree arg0, tree arg1)
+{
+  gimple_stmt_iterator gsi;
+  gimple cond;
+  edge true_edge, false_edge;
+  enum tree_code code;
+  bool emtpy_or_with_defined_p = true;
+
+  /* If the type says honor signed zeros we cannot do this
+     optimization.  */
+  if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
+    return 0;
+
+  /* If there is a statement in MIDDLE_BB that defines one of the PHI
+     arguments, then adjust arg0 or arg1.  */
+  gsi = gsi_after_labels (middle_bb);
+  if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
+    gsi_next_nondebug (&gsi);
+  while (!gsi_end_p (gsi))
+    {
+      gimple stmt = gsi_stmt (gsi);
+      tree lhs;
+      gsi_next_nondebug (&gsi);
+      if (!is_gimple_assign (stmt))
+	{
+	  emtpy_or_with_defined_p = false;
+	  continue;
+	}
+      /* Now try to adjust arg0 or arg1 according to the computation
+	 in the statement.  */
+      lhs = gimple_assign_lhs (stmt);
+      if (!(lhs == arg0
+	     && jump_function_from_stmt (&arg0, stmt))
+	    || (lhs == arg1
+		&& jump_function_from_stmt (&arg1, stmt)))
+	emtpy_or_with_defined_p = false;
+    }
+
+  cond = last_stmt (cond_bb);
+  code = gimple_cond_code (cond);
+
+  /* This transformation is only valid for equality comparisons.  */
+  if (code != NE_EXPR && code != EQ_EXPR)
+    return 0;
+
+  /* We need to know which is the true edge and which is the false
+      edge so that we know if have abs or negative abs.  */
+  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+
+  /* At this point we know we have a COND_EXPR with two successors.
+     One successor is BB, the other successor is an empty block which
+     falls through into BB.
+
+     The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR.
+
+     There is a single PHI node at the join point (BB) with two arguments.
+
+     We now need to verify that the two arguments in the PHI node match
+     the two arguments to the equality comparison.  */
+
+  if (operand_equal_for_value_replacement (arg0, arg1, &code, cond))
+    {
+      edge e;
+      tree arg;
+
+      /* For NE_EXPR, we want to build an assignment result = arg where
+	 arg is the PHI argument associated with the true edge.  For
+	 EQ_EXPR we want the PHI argument associated with the false edge.  */
+      e = (code == NE_EXPR ? true_edge : false_edge);
+
+      /* Unfortunately, E may not reach BB (it may instead have gone to
+	 OTHER_BLOCK).  If that is the case, then we want the single outgoing
+	 edge from OTHER_BLOCK which reaches BB and represents the desired
+	 path from COND_BLOCK.  */
+      if (e->dest == middle_bb)
+	e = single_succ_edge (e->dest);
+
+      /* Now we know the incoming edge to BB that has the argument for the
+	 RHS of our new assignment statement.  */
+      if (e0 == e)
+	arg = arg0;
+      else
+	arg = arg1;
+
+      /* If the middle basic block was empty or is defining the
+	 PHI arguments and this is a single phi where the args are different
+	 for the edges e0 and e1 then we can remove the middle basic block. */
+      if (emtpy_or_with_defined_p
+	  && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)),
+							    e0, e1))
+	{
+          replace_phi_edge_with_variable (cond_bb, e1, phi, arg);
+	  /* Note that we optimized this PHI.  */
+	  return 2;
+	}
+      else
+	{
+	  /* Replace the PHI arguments with arg. */
+	  SET_PHI_ARG_DEF (phi, e0->dest_idx, arg);
+	  SET_PHI_ARG_DEF (phi, e1->dest_idx, arg);
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "PHI ");
+	      print_generic_expr (dump_file, gimple_phi_result (phi), 0);
+	      fprintf (dump_file, " reduced for COND_EXPR in block %d to ",
+		       cond_bb->index);
+	      print_generic_expr (dump_file, arg, 0);
+	      fprintf (dump_file, ".\n");
+            }
+          return 1;
+	}
+
+    }
+  return 0;
+}
+
+/*  The function minmax_replacement does the main work of doing the minmax
+    replacement.  Return true if the replacement is done.  Otherwise return
+    false.
+    BB is the basic block where the replacement is going to be done on.  ARG0
+    is argument 0 from the PHI.  Likewise for ARG1.  */
+
+static bool
+minmax_replacement (basic_block cond_bb, basic_block middle_bb,
+		    edge e0, edge e1, gimple phi,
+		    tree arg0, tree arg1)
+{
+  tree result, type;
+  gimple cond, new_stmt;
+  edge true_edge, false_edge;
+  enum tree_code cmp, minmax, ass_code;
+  tree smaller, larger, arg_true, arg_false;
+  gimple_stmt_iterator gsi, gsi_from;
+
+  type = TREE_TYPE (PHI_RESULT (phi));
+
+  /* The optimization may be unsafe due to NaNs.  */
+  if (HONOR_NANS (TYPE_MODE (type)))
+    return false;
+
+  cond = last_stmt (cond_bb);
+  cmp = gimple_cond_code (cond);
+
+  /* This transformation is only valid for order comparisons.  Record which
+     operand is smaller/larger if the result of the comparison is true.  */
+  if (cmp == LT_EXPR || cmp == LE_EXPR)
+    {
+      smaller = gimple_cond_lhs (cond);
+      larger = gimple_cond_rhs (cond);
+    }
+  else if (cmp == GT_EXPR || cmp == GE_EXPR)
+    {
+      smaller = gimple_cond_rhs (cond);
+      larger = gimple_cond_lhs (cond);
+    }
+  else
+    return false;
+
+  /* We need to know which is the true edge and which is the false
+      edge so that we know if have abs or negative abs.  */
+  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+
+  /* Forward the edges over the middle basic block.  */
+  if (true_edge->dest == middle_bb)
+    true_edge = EDGE_SUCC (true_edge->dest, 0);
+  if (false_edge->dest == middle_bb)
+    false_edge = EDGE_SUCC (false_edge->dest, 0);
+
+  if (true_edge == e0)
+    {
+      gcc_assert (false_edge == e1);
+      arg_true = arg0;
+      arg_false = arg1;
+    }
+  else
+    {
+      gcc_assert (false_edge == e0);
+      gcc_assert (true_edge == e1);
+      arg_true = arg1;
+      arg_false = arg0;
+    }
+
+  if (empty_block_p (middle_bb))
+    {
+      if (operand_equal_for_phi_arg_p (arg_true, smaller)
+	  && operand_equal_for_phi_arg_p (arg_false, larger))
+	{
+	  /* Case
+
+	     if (smaller < larger)
+	     rslt = smaller;
+	     else
+	     rslt = larger;  */
+	  minmax = MIN_EXPR;
+	}
+      else if (operand_equal_for_phi_arg_p (arg_false, smaller)
+	       && operand_equal_for_phi_arg_p (arg_true, larger))
+	minmax = MAX_EXPR;
+      else
+	return false;
+    }
+  else
+    {
+      /* Recognize the following case, assuming d <= u:
+
+	 if (a <= u)
+	   b = MAX (a, d);
+	 x = PHI <b, u>
+
+	 This is equivalent to
+
+	 b = MAX (a, d);
+	 x = MIN (b, u);  */
+
+      gimple assign = last_and_only_stmt (middle_bb);
+      tree lhs, op0, op1, bound;
+
+      if (!assign
+	  || gimple_code (assign) != GIMPLE_ASSIGN)
+	return false;
+
+      lhs = gimple_assign_lhs (assign);
+      ass_code = gimple_assign_rhs_code (assign);
+      if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
+	return false;
+      op0 = gimple_assign_rhs1 (assign);
+      op1 = gimple_assign_rhs2 (assign);
+
+      if (true_edge->src == middle_bb)
+	{
+	  /* We got here if the condition is true, i.e., SMALLER < LARGER.  */
+	  if (!operand_equal_for_phi_arg_p (lhs, arg_true))
+	    return false;
+
+	  if (operand_equal_for_phi_arg_p (arg_false, larger))
+	    {
+	      /* Case
+
+		 if (smaller < larger)
+		   {
+		     r' = MAX_EXPR (smaller, bound)
+		   }
+		 r = PHI <r', larger>  --> to be turned to MIN_EXPR.  */
+	      if (ass_code != MAX_EXPR)
+		return false;
+
+	      minmax = MIN_EXPR;
+	      if (operand_equal_for_phi_arg_p (op0, smaller))
+		bound = op1;
+	      else if (operand_equal_for_phi_arg_p (op1, smaller))
+		bound = op0;
+	      else
+		return false;
+
+	      /* We need BOUND <= LARGER.  */
+	      if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
+						  bound, larger)))
+		return false;
+	    }
+	  else if (operand_equal_for_phi_arg_p (arg_false, smaller))
+	    {
+	      /* Case
+
+		 if (smaller < larger)
+		   {
+		     r' = MIN_EXPR (larger, bound)
+		   }
+		 r = PHI <r', smaller>  --> to be turned to MAX_EXPR.  */
+	      if (ass_code != MIN_EXPR)
+		return false;
+
+	      minmax = MAX_EXPR;
+	      if (operand_equal_for_phi_arg_p (op0, larger))
+		bound = op1;
+	      else if (operand_equal_for_phi_arg_p (op1, larger))
+		bound = op0;
+	      else
+		return false;
+
+	      /* We need BOUND >= SMALLER.  */
+	      if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
+						  bound, smaller)))
+		return false;
+	    }
+	  else
+	    return false;
+	}
+      else
+	{
+	  /* We got here if the condition is false, i.e., SMALLER > LARGER.  */
+	  if (!operand_equal_for_phi_arg_p (lhs, arg_false))
+	    return false;
+
+	  if (operand_equal_for_phi_arg_p (arg_true, larger))
+	    {
+	      /* Case
+
+		 if (smaller > larger)
+		   {
+		     r' = MIN_EXPR (smaller, bound)
+		   }
+		 r = PHI <r', larger>  --> to be turned to MAX_EXPR.  */
+	      if (ass_code != MIN_EXPR)
+		return false;
+
+	      minmax = MAX_EXPR;
+	      if (operand_equal_for_phi_arg_p (op0, smaller))
+		bound = op1;
+	      else if (operand_equal_for_phi_arg_p (op1, smaller))
+		bound = op0;
+	      else
+		return false;
+
+	      /* We need BOUND >= LARGER.  */
+	      if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node,
+						  bound, larger)))
+		return false;
+	    }
+	  else if (operand_equal_for_phi_arg_p (arg_true, smaller))
+	    {
+	      /* Case
+
+		 if (smaller > larger)
+		   {
+		     r' = MAX_EXPR (larger, bound)
+		   }
+		 r = PHI <r', smaller>  --> to be turned to MIN_EXPR.  */
+	      if (ass_code != MAX_EXPR)
+		return false;
+
+	      minmax = MIN_EXPR;
+	      if (operand_equal_for_phi_arg_p (op0, larger))
+		bound = op1;
+	      else if (operand_equal_for_phi_arg_p (op1, larger))
+		bound = op0;
+	      else
+		return false;
+
+	      /* We need BOUND <= SMALLER.  */
+	      if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node,
+						  bound, smaller)))
+		return false;
+	    }
+	  else
+	    return false;
+	}
+
+      /* Move the statement from the middle block.  */
+      gsi = gsi_last_bb (cond_bb);
+      gsi_from = gsi_last_nondebug_bb (middle_bb);
+      gsi_move_before (&gsi_from, &gsi);
+    }
+
+  /* Emit the statement to compute min/max.  */
+  result = duplicate_ssa_name (PHI_RESULT (phi), NULL);
+  new_stmt = gimple_build_assign_with_ops (minmax, result, arg0, arg1);
+  gsi = gsi_last_bb (cond_bb);
+  gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
+
+  replace_phi_edge_with_variable (cond_bb, e1, phi, result);
+  return true;
+}
+
+/*  The function absolute_replacement does the main work of doing the absolute
+    replacement.  Return true if the replacement is done.  Otherwise return
+    false.
+    bb is the basic block where the replacement is going to be done on.  arg0
+    is argument 0 from the phi.  Likewise for arg1.  */
+
+static bool
+abs_replacement (basic_block cond_bb, basic_block middle_bb,
+		 edge e0 ATTRIBUTE_UNUSED, edge e1,
+		 gimple phi, tree arg0, tree arg1)
+{
+  tree result;
+  gimple new_stmt, cond;
+  gimple_stmt_iterator gsi;
+  edge true_edge, false_edge;
+  gimple assign;
+  edge e;
+  tree rhs, lhs;
+  bool negate;
+  enum tree_code cond_code;
+
+  /* If the type says honor signed zeros we cannot do this
+     optimization.  */
+  if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
+    return false;
+
+  /* OTHER_BLOCK must have only one executable statement which must have the
+     form arg0 = -arg1 or arg1 = -arg0.  */
+
+  assign = last_and_only_stmt (middle_bb);
+  /* If we did not find the proper negation assignment, then we can not
+     optimize.  */
+  if (assign == NULL)
+    return false;
+
+  /* If we got here, then we have found the only executable statement
+     in OTHER_BLOCK.  If it is anything other than arg = -arg1 or
+     arg1 = -arg0, then we can not optimize.  */
+  if (gimple_code (assign) != GIMPLE_ASSIGN)
+    return false;
+
+  lhs = gimple_assign_lhs (assign);
+
+  if (gimple_assign_rhs_code (assign) != NEGATE_EXPR)
+    return false;
+
+  rhs = gimple_assign_rhs1 (assign);
+
+  /* The assignment has to be arg0 = -arg1 or arg1 = -arg0.  */
+  if (!(lhs == arg0 && rhs == arg1)
+      && !(lhs == arg1 && rhs == arg0))
+    return false;
+
+  cond = last_stmt (cond_bb);
+  result = PHI_RESULT (phi);
+
+  /* Only relationals comparing arg[01] against zero are interesting.  */
+  cond_code = gimple_cond_code (cond);
+  if (cond_code != GT_EXPR && cond_code != GE_EXPR
+      && cond_code != LT_EXPR && cond_code != LE_EXPR)
+    return false;
+
+  /* Make sure the conditional is arg[01] OP y.  */
+  if (gimple_cond_lhs (cond) != rhs)
+    return false;
+
+  if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond)))
+	       ? real_zerop (gimple_cond_rhs (cond))
+	       : integer_zerop (gimple_cond_rhs (cond)))
+    ;
+  else
+    return false;
+
+  /* We need to know which is the true edge and which is the false
+     edge so that we know if have abs or negative abs.  */
+  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+
+  /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we
+     will need to negate the result.  Similarly for LT_EXPR/LE_EXPR if
+     the false edge goes to OTHER_BLOCK.  */
+  if (cond_code == GT_EXPR || cond_code == GE_EXPR)
+    e = true_edge;
+  else
+    e = false_edge;
+
+  if (e->dest == middle_bb)
+    negate = true;
+  else
+    negate = false;
+
+  result = duplicate_ssa_name (result, NULL);
+
+  if (negate)
+    lhs = make_ssa_name (TREE_TYPE (result), NULL);
+  else
+    lhs = result;
+
+  /* Build the modify expression with abs expression.  */
+  new_stmt = gimple_build_assign_with_ops (ABS_EXPR, lhs, rhs, NULL);
+
+  gsi = gsi_last_bb (cond_bb);
+  gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
+
+  if (negate)
+    {
+      /* Get the right GSI.  We want to insert after the recently
+	 added ABS_EXPR statement (which we know is the first statement
+	 in the block.  */
+      new_stmt = gimple_build_assign_with_ops (NEGATE_EXPR, result, lhs, NULL);
+
+      gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+    }
+
+  replace_phi_edge_with_variable (cond_bb, e1, phi, result);
+
+  /* Note that we optimized this PHI.  */
+  return true;
+}
+
+/*  The function neg_replacement replaces conditional negation with
+    equivalent straight line code.  Returns TRUE if replacement is done,
+    otherwise returns FALSE.
+
+    COND_BB branches around negation occuring in MIDDLE_BB.
+
+    E0 and E1 are edges out of COND_BB.  E0 reaches MIDDLE_BB and
+    E1 reaches the other successor which should contain PHI with
+    arguments ARG0 and ARG1.
+
+    Assuming negation is to occur when the condition is true,
+    then the non-branching sequence is:
+
+       result = (rhs ^ -cond) + cond
+
+    Inverting the condition or its result gives us negation
+    when the original condition is false.  */
+
+static bool
+neg_replacement (basic_block cond_bb, basic_block middle_bb,
+		 edge e0 ATTRIBUTE_UNUSED, edge e1,
+		 gimple phi, tree arg0, tree arg1)
+{
+  gimple new_stmt, cond;
+  gimple_stmt_iterator gsi;
+  gimple assign;
+  edge true_edge, false_edge;
+  tree rhs, lhs;
+  enum tree_code cond_code;
+  bool invert = false;
+
+  /* This transformation performs logical operations on the
+     incoming arguments.  So force them to be integral types.   */
+  if (!INTEGRAL_TYPE_P (TREE_TYPE (arg0)))
+    return false;
+
+  /* OTHER_BLOCK must have only one executable statement which must have the
+     form arg0 = -arg1 or arg1 = -arg0.  */
+
+  assign = last_and_only_stmt (middle_bb);
+  /* If we did not find the proper negation assignment, then we can not
+     optimize.  */
+  if (assign == NULL)
+    return false;
+
+  /* If we got here, then we have found the only executable statement
+     in OTHER_BLOCK.  If it is anything other than arg0 = -arg1 or
+     arg1 = -arg0, then we can not optimize.  */
+  if (gimple_code (assign) != GIMPLE_ASSIGN)
+    return false;
+
+  lhs = gimple_assign_lhs (assign);
+
+  if (gimple_assign_rhs_code (assign) != NEGATE_EXPR)
+    return false;
+
+  rhs = gimple_assign_rhs1 (assign);
+
+  /* The assignment has to be arg0 = -arg1 or arg1 = -arg0.  */
+  if (!(lhs == arg0 && rhs == arg1)
+      && !(lhs == arg1 && rhs == arg0))
+    return false;
+
+  /* The basic sequence assumes we negate when the condition is true.
+     If we need the opposite, then we will either need to invert the
+     condition or its result.  */
+  extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
+  invert = false_edge->dest == middle_bb;
+
+  /* Unlike abs_replacement, we can handle arbitrary conditionals here.  */
+  cond = last_stmt (cond_bb);
+  cond_code = gimple_cond_code (cond);
+
+  /* If inversion is needed, first try to invert the test since
+     that's cheapest.  */
+  if (invert)
+    {
+      bool honor_nans
+	= HONOR_NANS (TYPE_MODE (TREE_TYPE (gimple_cond_lhs (cond))));
+      enum tree_code new_code = invert_tree_comparison (cond_code, honor_nans);
+
+      /* If invert_tree_comparison was successful, then use its return
+	 value as the new code and note that inversion is no longer
+	 needed.  */
+      if (new_code != ERROR_MARK)
+	{
+	  cond_code = new_code;
+	  invert = false;
+	}
+    }
+
+  tree cond_val = make_ssa_name (boolean_type_node, NULL);
+  new_stmt = gimple_build_assign_with_ops (cond_code, cond_val,
+					   gimple_cond_lhs (cond),
+					   gimple_cond_rhs (cond));
+  gsi = gsi_last_bb (cond_bb);
+  gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
+
+  /* If we still need inversion, then invert the result of the
+     condition.  */
+  if (invert)
+    {
+      tree tmp = make_ssa_name (boolean_type_node, NULL);
+      new_stmt = gimple_build_assign_with_ops (BIT_XOR_EXPR, tmp,
+					       cond_val, boolean_true_node);
+      gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+      cond_val = tmp;
+    }
+
+  /* Get the condition in the right type so that we can perform
+     logical and arithmetic operations on it.  */
+  tree cond_val_converted = make_ssa_name (TREE_TYPE (rhs), NULL);
+  new_stmt = gimple_build_assign_with_ops (NOP_EXPR, cond_val_converted,
+					   cond_val, NULL_TREE);
+  gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+
+  tree neg_cond_val_converted = make_ssa_name (TREE_TYPE (rhs), NULL);
+  new_stmt = gimple_build_assign_with_ops (NEGATE_EXPR, neg_cond_val_converted,
+					   cond_val_converted, NULL_TREE);
+  gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+
+  tree tmp = make_ssa_name (TREE_TYPE (rhs), NULL);
+  new_stmt = gimple_build_assign_with_ops (BIT_XOR_EXPR, tmp,
+					   rhs, neg_cond_val_converted);
+  gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+
+  tree new_lhs = make_ssa_name (TREE_TYPE (rhs), NULL);
+  new_stmt = gimple_build_assign_with_ops (PLUS_EXPR, new_lhs,
+					   tmp, cond_val_converted);
+  gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+
+  replace_phi_edge_with_variable (cond_bb, e1, phi, new_lhs);
+
+  /* Note that we optimized this PHI.  */
+  return true;
+}
+
+/* Auxiliary functions to determine the set of memory accesses which
+   can't trap because they are preceded by accesses to the same memory
+   portion.  We do that for MEM_REFs, so we only need to track
+   the SSA_NAME of the pointer indirectly referenced.  The algorithm
+   simply is a walk over all instructions in dominator order.  When
+   we see an MEM_REF we determine if we've already seen a same
+   ref anywhere up to the root of the dominator tree.  If we do the
+   current access can't trap.  If we don't see any dominating access
+   the current access might trap, but might also make later accesses
+   non-trapping, so we remember it.  We need to be careful with loads
+   or stores, for instance a load might not trap, while a store would,
+   so if we see a dominating read access this doesn't mean that a later
+   write access would not trap.  Hence we also need to differentiate the
+   type of access(es) seen.
+
+   ??? We currently are very conservative and assume that a load might
+   trap even if a store doesn't (write-only memory).  This probably is
+   overly conservative.  */
+
+/* A hash-table of SSA_NAMEs, and in which basic block an MEM_REF
+   through it was seen, which would constitute a no-trap region for
+   same accesses.  */
+struct name_to_bb
+{
+  unsigned int ssa_name_ver;
+  unsigned int phase;
+  bool store;
+  HOST_WIDE_INT offset, size;
+  basic_block bb;
+};
+
+/* Hashtable helpers.  */
+
+struct ssa_names_hasher : typed_free_remove <name_to_bb>
+{
+  typedef name_to_bb value_type;
+  typedef name_to_bb compare_type;
+  static inline hashval_t hash (const value_type *);
+  static inline bool equal (const value_type *, const compare_type *);
+};
+
+/* Used for quick clearing of the hash-table when we see calls.
+   Hash entries with phase < nt_call_phase are invalid.  */
+static unsigned int nt_call_phase;
+
+/* The hash function.  */
+
+inline hashval_t
+ssa_names_hasher::hash (const value_type *n)
+{
+  return n->ssa_name_ver ^ (((hashval_t) n->store) << 31)
+         ^ (n->offset << 6) ^ (n->size << 3);
+}
+
+/* The equality function of *P1 and *P2.  */
+
+inline bool
+ssa_names_hasher::equal (const value_type *n1, const compare_type *n2)
+{
+  return n1->ssa_name_ver == n2->ssa_name_ver
+         && n1->store == n2->store
+         && n1->offset == n2->offset
+         && n1->size == n2->size;
+}
+
+/* The hash table for remembering what we've seen.  */
+static hash_table <ssa_names_hasher> seen_ssa_names;
+
+/* We see the expression EXP in basic block BB.  If it's an interesting
+   expression (an MEM_REF through an SSA_NAME) possibly insert the
+   expression into the set NONTRAP or the hash table of seen expressions.
+   STORE is true if this expression is on the LHS, otherwise it's on
+   the RHS.  */
+static void
+add_or_mark_expr (basic_block bb, tree exp,
+		  struct pointer_set_t *nontrap, bool store)
+{
+  HOST_WIDE_INT size;
+
+  if (TREE_CODE (exp) == MEM_REF
+      && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME
+      && tree_fits_shwi_p (TREE_OPERAND (exp, 1))
+      && (size = int_size_in_bytes (TREE_TYPE (exp))) > 0)
+    {
+      tree name = TREE_OPERAND (exp, 0);
+      struct name_to_bb map;
+      name_to_bb **slot;
+      struct name_to_bb *n2bb;
+      basic_block found_bb = 0;
+
+      /* Try to find the last seen MEM_REF through the same
+         SSA_NAME, which can trap.  */
+      map.ssa_name_ver = SSA_NAME_VERSION (name);
+      map.phase = 0;
+      map.bb = 0;
+      map.store = store;
+      map.offset = tree_to_shwi (TREE_OPERAND (exp, 1));
+      map.size = size;
+
+      slot = seen_ssa_names.find_slot (&map, INSERT);
+      n2bb = *slot;
+      if (n2bb && n2bb->phase >= nt_call_phase)
+        found_bb = n2bb->bb;
+
+      /* If we've found a trapping MEM_REF, _and_ it dominates EXP
+         (it's in a basic block on the path from us to the dominator root)
+	 then we can't trap.  */
+      if (found_bb && (((size_t)found_bb->aux) & 1) == 1)
+	{
+	  pointer_set_insert (nontrap, exp);
+	}
+      else
+        {
+	  /* EXP might trap, so insert it into the hash table.  */
+	  if (n2bb)
+	    {
+	      n2bb->phase = nt_call_phase;
+	      n2bb->bb = bb;
+	    }
+	  else
+	    {
+	      n2bb = XNEW (struct name_to_bb);
+	      n2bb->ssa_name_ver = SSA_NAME_VERSION (name);
+	      n2bb->phase = nt_call_phase;
+	      n2bb->bb = bb;
+	      n2bb->store = store;
+	      n2bb->offset = map.offset;
+	      n2bb->size = size;
+	      *slot = n2bb;
+	    }
+	}
+    }
+}
+
+class nontrapping_dom_walker : public dom_walker
+{
+public:
+  nontrapping_dom_walker (cdi_direction direction, pointer_set_t *ps)
+    : dom_walker (direction), m_nontrapping (ps) {}
+
+  virtual void before_dom_children (basic_block);
+  virtual void after_dom_children (basic_block);
+
+private:
+  pointer_set_t *m_nontrapping;
+};
+
+/* Called by walk_dominator_tree, when entering the block BB.  */
+void
+nontrapping_dom_walker::before_dom_children (basic_block bb)
+{
+  edge e;
+  edge_iterator ei;
+  gimple_stmt_iterator gsi;
+
+  /* If we haven't seen all our predecessors, clear the hash-table.  */
+  FOR_EACH_EDGE (e, ei, bb->preds)
+    if ((((size_t)e->src->aux) & 2) == 0)
+      {
+	nt_call_phase++;
+	break;
+      }
+
+  /* Mark this BB as being on the path to dominator root and as visited.  */
+  bb->aux = (void*)(1 | 2);
+
+  /* And walk the statements in order.  */
+  for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      gimple stmt = gsi_stmt (gsi);
+
+      if (is_gimple_call (stmt) && !nonfreeing_call_p (stmt))
+	nt_call_phase++;
+      else if (gimple_assign_single_p (stmt) && !gimple_has_volatile_ops (stmt))
+	{
+	  add_or_mark_expr (bb, gimple_assign_lhs (stmt), m_nontrapping, true);
+	  add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), m_nontrapping, false);
+	}
+    }
+}
+
+/* Called by walk_dominator_tree, when basic block BB is exited.  */
+void
+nontrapping_dom_walker::after_dom_children (basic_block bb)
+{
+  /* This BB isn't on the path to dominator root anymore.  */
+  bb->aux = (void*)2;
+}
+
+/* This is the entry point of gathering non trapping memory accesses.
+   It will do a dominator walk over the whole function, and it will
+   make use of the bb->aux pointers.  It returns a set of trees
+   (the MEM_REFs itself) which can't trap.  */
+static struct pointer_set_t *
+get_non_trapping (void)
+{
+  nt_call_phase = 0;
+  pointer_set_t *nontrap = pointer_set_create ();
+  seen_ssa_names.create (128);
+  /* We're going to do a dominator walk, so ensure that we have
+     dominance information.  */
+  calculate_dominance_info (CDI_DOMINATORS);
+
+  nontrapping_dom_walker (CDI_DOMINATORS, nontrap)
+    .walk (cfun->cfg->x_entry_block_ptr);
+
+  seen_ssa_names.dispose ();
+
+  clear_aux_for_blocks ();
+  return nontrap;
+}
+
+/* Do the main work of conditional store replacement.  We already know
+   that the recognized pattern looks like so:
+
+   split:
+     if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1)
+   MIDDLE_BB:
+     something
+     fallthrough (edge E0)
+   JOIN_BB:
+     some more
+
+   We check that MIDDLE_BB contains only one store, that that store
+   doesn't trap (not via NOTRAP, but via checking if an access to the same
+   memory location dominates us) and that the store has a "simple" RHS.  */
+
+static bool
+cond_store_replacement (basic_block middle_bb, basic_block join_bb,
+			edge e0, edge e1, struct pointer_set_t *nontrap)
+{
+  gimple assign = last_and_only_stmt (middle_bb);
+  tree lhs, rhs, name, name2;
+  gimple newphi, new_stmt;
+  gimple_stmt_iterator gsi;
+  source_location locus;
+
+  /* Check if middle_bb contains of only one store.  */
+  if (!assign
+      || !gimple_assign_single_p (assign)
+      || gimple_has_volatile_ops (assign))
+    return false;
+
+  locus = gimple_location (assign);
+  lhs = gimple_assign_lhs (assign);
+  rhs = gimple_assign_rhs1 (assign);
+  if (TREE_CODE (lhs) != MEM_REF
+      || TREE_CODE (TREE_OPERAND (lhs, 0)) != SSA_NAME
+      || !is_gimple_reg_type (TREE_TYPE (lhs)))
+    return false;
+
+  /* Prove that we can move the store down.  We could also check
+     TREE_THIS_NOTRAP here, but in that case we also could move stores,
+     whose value is not available readily, which we want to avoid.  */
+  if (!pointer_set_contains (nontrap, lhs))
+    return false;
+
+  /* Now we've checked the constraints, so do the transformation:
+     1) Remove the single store.  */
+  gsi = gsi_for_stmt (assign);
+  unlink_stmt_vdef (assign);
+  gsi_remove (&gsi, true);
+  release_defs (assign);
+
+  /* 2) Insert a load from the memory of the store to the temporary
+        on the edge which did not contain the store.  */
+  lhs = unshare_expr (lhs);
+  name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
+  new_stmt = gimple_build_assign (name, lhs);
+  gimple_set_location (new_stmt, locus);
+  gsi_insert_on_edge (e1, new_stmt);
+
+  /* 3) Create a PHI node at the join block, with one argument
+        holding the old RHS, and the other holding the temporary
+        where we stored the old memory contents.  */
+  name2 = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
+  newphi = create_phi_node (name2, join_bb);
+  add_phi_arg (newphi, rhs, e0, locus);
+  add_phi_arg (newphi, name, e1, locus);
+
+  lhs = unshare_expr (lhs);
+  new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
+
+  /* 4) Insert that PHI node.  */
+  gsi = gsi_after_labels (join_bb);
+  if (gsi_end_p (gsi))
+    {
+      gsi = gsi_last_bb (join_bb);
+      gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+    }
+  else
+    gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
+
+  return true;
+}
+
+/* Do the main work of conditional store replacement.  */
+
+static bool
+cond_if_else_store_replacement_1 (basic_block then_bb, basic_block else_bb,
+				  basic_block join_bb, gimple then_assign,
+				  gimple else_assign)
+{
+  tree lhs_base, lhs, then_rhs, else_rhs, name;
+  source_location then_locus, else_locus;
+  gimple_stmt_iterator gsi;
+  gimple newphi, new_stmt;
+
+  if (then_assign == NULL
+      || !gimple_assign_single_p (then_assign)
+      || gimple_clobber_p (then_assign)
+      || gimple_has_volatile_ops (then_assign)
+      || else_assign == NULL
+      || !gimple_assign_single_p (else_assign)
+      || gimple_clobber_p (else_assign)
+      || gimple_has_volatile_ops (else_assign))
+    return false;
+
+  lhs = gimple_assign_lhs (then_assign);
+  if (!is_gimple_reg_type (TREE_TYPE (lhs))
+      || !operand_equal_p (lhs, gimple_assign_lhs (else_assign), 0))
+    return false;
+
+  lhs_base = get_base_address (lhs);
+  if (lhs_base == NULL_TREE
+      || (!DECL_P (lhs_base) && TREE_CODE (lhs_base) != MEM_REF))
+    return false;
+
+  then_rhs = gimple_assign_rhs1 (then_assign);
+  else_rhs = gimple_assign_rhs1 (else_assign);
+  then_locus = gimple_location (then_assign);
+  else_locus = gimple_location (else_assign);
+
+  /* Now we've checked the constraints, so do the transformation:
+     1) Remove the stores.  */
+  gsi = gsi_for_stmt (then_assign);
+  unlink_stmt_vdef (then_assign);
+  gsi_remove (&gsi, true);
+  release_defs (then_assign);
+
+  gsi = gsi_for_stmt (else_assign);
+  unlink_stmt_vdef (else_assign);
+  gsi_remove (&gsi, true);
+  release_defs (else_assign);
+
+  /* 2) Create a PHI node at the join block, with one argument
+	holding the old RHS, and the other holding the temporary
+	where we stored the old memory contents.  */
+  name = make_temp_ssa_name (TREE_TYPE (lhs), NULL, "cstore");
+  newphi = create_phi_node (name, join_bb);
+  add_phi_arg (newphi, then_rhs, EDGE_SUCC (then_bb, 0), then_locus);
+  add_phi_arg (newphi, else_rhs, EDGE_SUCC (else_bb, 0), else_locus);
+
+  new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
+
+  /* 3) Insert that PHI node.  */
+  gsi = gsi_after_labels (join_bb);
+  if (gsi_end_p (gsi))
+    {
+      gsi = gsi_last_bb (join_bb);
+      gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT);
+    }
+  else
+    gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
+
+  return true;
+}
+
+/* Conditional store replacement.  We already know
+   that the recognized pattern looks like so:
+
+   split:
+     if (cond) goto THEN_BB; else goto ELSE_BB (edge E1)
+   THEN_BB:
+     ...
+     X = Y;
+     ...
+     goto JOIN_BB;
+   ELSE_BB:
+     ...
+     X = Z;
+     ...
+     fallthrough (edge E0)
+   JOIN_BB:
+     some more
+
+   We check that it is safe to sink the store to JOIN_BB by verifying that
+   there are no read-after-write or write-after-write dependencies in
+   THEN_BB and ELSE_BB.  */
+
+static bool
+cond_if_else_store_replacement (basic_block then_bb, basic_block else_bb,
+                                basic_block join_bb)
+{
+  gimple then_assign = last_and_only_stmt (then_bb);
+  gimple else_assign = last_and_only_stmt (else_bb);
+  vec<data_reference_p> then_datarefs, else_datarefs;
+  vec<ddr_p> then_ddrs, else_ddrs;
+  gimple then_store, else_store;
+  bool found, ok = false, res;
+  struct data_dependence_relation *ddr;
+  data_reference_p then_dr, else_dr;
+  int i, j;
+  tree then_lhs, else_lhs;
+  basic_block blocks[3];
+
+  if (MAX_STORES_TO_SINK == 0)
+    return false;
+
+  /* Handle the case with single statement in THEN_BB and ELSE_BB.  */
+  if (then_assign && else_assign)
+    return cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
+                                             then_assign, else_assign);
+
+  /* Find data references.  */
+  then_datarefs.create (1);
+  else_datarefs.create (1);
+  if ((find_data_references_in_bb (NULL, then_bb, &then_datarefs)
+        == chrec_dont_know)
+      || !then_datarefs.length ()
+      || (find_data_references_in_bb (NULL, else_bb, &else_datarefs)
+	  == chrec_dont_know)
+      || !else_datarefs.length ())
+    {
+      free_data_refs (then_datarefs);
+      free_data_refs (else_datarefs);
+      return false;
+    }
+
+  /* Find pairs of stores with equal LHS.  */
+  auto_vec<gimple, 1> then_stores, else_stores;
+  FOR_EACH_VEC_ELT (then_datarefs, i, then_dr)
+    {
+      if (DR_IS_READ (then_dr))
+        continue;
+
+      then_store = DR_STMT (then_dr);
+      then_lhs = gimple_get_lhs (then_store);
+      if (then_lhs == NULL_TREE)
+	continue;
+      found = false;
+
+      FOR_EACH_VEC_ELT (else_datarefs, j, else_dr)
+        {
+          if (DR_IS_READ (else_dr))
+            continue;
+
+          else_store = DR_STMT (else_dr);
+          else_lhs = gimple_get_lhs (else_store);
+	  if (else_lhs == NULL_TREE)
+	    continue;
+
+          if (operand_equal_p (then_lhs, else_lhs, 0))
+            {
+              found = true;
+              break;
+            }
+        }
+
+      if (!found)
+        continue;
+
+      then_stores.safe_push (then_store);
+      else_stores.safe_push (else_store);
+    }
+
+  /* No pairs of stores found.  */
+  if (!then_stores.length ()
+      || then_stores.length () > (unsigned) MAX_STORES_TO_SINK)
+    {
+      free_data_refs (then_datarefs);
+      free_data_refs (else_datarefs);
+      return false;
+    }
+
+  /* Compute and check data dependencies in both basic blocks.  */
+  then_ddrs.create (1);
+  else_ddrs.create (1);
+  if (!compute_all_dependences (then_datarefs, &then_ddrs,
+				vNULL, false)
+      || !compute_all_dependences (else_datarefs, &else_ddrs,
+				   vNULL, false))
+    {
+      free_dependence_relations (then_ddrs);
+      free_dependence_relations (else_ddrs);
+      free_data_refs (then_datarefs);
+      free_data_refs (else_datarefs);
+      return false;
+    }
+  blocks[0] = then_bb;
+  blocks[1] = else_bb;
+  blocks[2] = join_bb;
+  renumber_gimple_stmt_uids_in_blocks (blocks, 3);
+
+  /* Check that there are no read-after-write or write-after-write dependencies
+     in THEN_BB.  */
+  FOR_EACH_VEC_ELT (then_ddrs, i, ddr)
+    {
+      struct data_reference *dra = DDR_A (ddr);
+      struct data_reference *drb = DDR_B (ddr);
+
+      if (DDR_ARE_DEPENDENT (ddr) != chrec_known
+          && ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
+               && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
+              || (DR_IS_READ (drb) && DR_IS_WRITE (dra)
+                  && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
+              || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
+        {
+          free_dependence_relations (then_ddrs);
+          free_dependence_relations (else_ddrs);
+	  free_data_refs (then_datarefs);
+	  free_data_refs (else_datarefs);
+          return false;
+        }
+    }
+
+  /* Check that there are no read-after-write or write-after-write dependencies
+     in ELSE_BB.  */
+  FOR_EACH_VEC_ELT (else_ddrs, i, ddr)
+    {
+      struct data_reference *dra = DDR_A (ddr);
+      struct data_reference *drb = DDR_B (ddr);
+
+      if (DDR_ARE_DEPENDENT (ddr) != chrec_known
+          && ((DR_IS_READ (dra) && DR_IS_WRITE (drb)
+               && gimple_uid (DR_STMT (dra)) > gimple_uid (DR_STMT (drb)))
+              || (DR_IS_READ (drb) && DR_IS_WRITE (dra)
+                  && gimple_uid (DR_STMT (drb)) > gimple_uid (DR_STMT (dra)))
+              || (DR_IS_WRITE (dra) && DR_IS_WRITE (drb))))
+        {
+          free_dependence_relations (then_ddrs);
+          free_dependence_relations (else_ddrs);
+	  free_data_refs (then_datarefs);
+	  free_data_refs (else_datarefs);
+          return false;
+        }
+    }
+
+  /* Sink stores with same LHS.  */
+  FOR_EACH_VEC_ELT (then_stores, i, then_store)
+    {
+      else_store = else_stores[i];
+      res = cond_if_else_store_replacement_1 (then_bb, else_bb, join_bb,
+                                              then_store, else_store);
+      ok = ok || res;
+    }
+
+  free_dependence_relations (then_ddrs);
+  free_dependence_relations (else_ddrs);
+  free_data_refs (then_datarefs);
+  free_data_refs (else_datarefs);
+
+  return ok;
+}
+
+/* Return TRUE if STMT has a VUSE whose corresponding VDEF is in BB.  */
+
+static bool
+local_mem_dependence (gimple stmt, basic_block bb)
+{
+  tree vuse = gimple_vuse (stmt);
+  gimple def;
+
+  if (!vuse)
+    return false;
+
+  def = SSA_NAME_DEF_STMT (vuse);
+  return (def && gimple_bb (def) == bb);
+}
+
+/* Given a "diamond" control-flow pattern where BB0 tests a condition,
+   BB1 and BB2 are "then" and "else" blocks dependent on this test,
+   and BB3 rejoins control flow following BB1 and BB2, look for
+   opportunities to hoist loads as follows.  If BB3 contains a PHI of
+   two loads, one each occurring in BB1 and BB2, and the loads are
+   provably of adjacent fields in the same structure, then move both
+   loads into BB0.  Of course this can only be done if there are no
+   dependencies preventing such motion.
+
+   One of the hoisted loads will always be speculative, so the
+   transformation is currently conservative:
+
+    - The fields must be strictly adjacent.
+    - The two fields must occupy a single memory block that is
+      guaranteed to not cross a page boundary.
+
+    The last is difficult to prove, as such memory blocks should be
+    aligned on the minimum of the stack alignment boundary and the
+    alignment guaranteed by heap allocation interfaces.  Thus we rely
+    on a parameter for the alignment value.
+
+    Provided a good value is used for the last case, the first
+    restriction could possibly be relaxed.  */
+
+static void
+hoist_adjacent_loads (basic_block bb0, basic_block bb1,
+		      basic_block bb2, basic_block bb3)
+{
+  int param_align = PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE);
+  unsigned param_align_bits = (unsigned) (param_align * BITS_PER_UNIT);
+  gimple_stmt_iterator gsi;
+
+  /* Walk the phis in bb3 looking for an opportunity.  We are looking
+     for phis of two SSA names, one each of which is defined in bb1 and
+     bb2.  */
+  for (gsi = gsi_start_phis (bb3); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      gimple phi_stmt = gsi_stmt (gsi);
+      gimple def1, def2, defswap;
+      tree arg1, arg2, ref1, ref2, field1, field2, fieldswap;
+      tree tree_offset1, tree_offset2, tree_size2, next;
+      int offset1, offset2, size2;
+      unsigned align1;
+      gimple_stmt_iterator gsi2;
+      basic_block bb_for_def1, bb_for_def2;
+
+      if (gimple_phi_num_args (phi_stmt) != 2
+	  || virtual_operand_p (gimple_phi_result (phi_stmt)))
+	continue;
+
+      arg1 = gimple_phi_arg_def (phi_stmt, 0);
+      arg2 = gimple_phi_arg_def (phi_stmt, 1);
+
+      if (TREE_CODE (arg1) != SSA_NAME
+	  || TREE_CODE (arg2) != SSA_NAME
+	  || SSA_NAME_IS_DEFAULT_DEF (arg1)
+	  || SSA_NAME_IS_DEFAULT_DEF (arg2))
+	continue;
+
+      def1 = SSA_NAME_DEF_STMT (arg1);
+      def2 = SSA_NAME_DEF_STMT (arg2);
+
+      if ((gimple_bb (def1) != bb1 || gimple_bb (def2) != bb2)
+	  && (gimple_bb (def2) != bb1 || gimple_bb (def1) != bb2))
+	continue;
+
+      /* Check the mode of the arguments to be sure a conditional move
+	 can be generated for it.  */
+      if (optab_handler (movcc_optab, TYPE_MODE (TREE_TYPE (arg1)))
+	  == CODE_FOR_nothing)
+	continue;
+
+      /* Both statements must be assignments whose RHS is a COMPONENT_REF.  */
+      if (!gimple_assign_single_p (def1)
+	  || !gimple_assign_single_p (def2)
+	  || gimple_has_volatile_ops (def1)
+	  || gimple_has_volatile_ops (def2))
+	continue;
+
+      ref1 = gimple_assign_rhs1 (def1);
+      ref2 = gimple_assign_rhs1 (def2);
+
+      if (TREE_CODE (ref1) != COMPONENT_REF
+	  || TREE_CODE (ref2) != COMPONENT_REF)
+	continue;
+
+      /* The zeroth operand of the two component references must be
+	 identical.  It is not sufficient to compare get_base_address of
+	 the two references, because this could allow for different
+	 elements of the same array in the two trees.  It is not safe to
+	 assume that the existence of one array element implies the
+	 existence of a different one.  */
+      if (!operand_equal_p (TREE_OPERAND (ref1, 0), TREE_OPERAND (ref2, 0), 0))
+	continue;
+
+      field1 = TREE_OPERAND (ref1, 1);
+      field2 = TREE_OPERAND (ref2, 1);
+
+      /* Check for field adjacency, and ensure field1 comes first.  */
+      for (next = DECL_CHAIN (field1);
+	   next && TREE_CODE (next) != FIELD_DECL;
+	   next = DECL_CHAIN (next))
+	;
+
+      if (next != field2)
+	{
+	  for (next = DECL_CHAIN (field2);
+	       next && TREE_CODE (next) != FIELD_DECL;
+	       next = DECL_CHAIN (next))
+	    ;
+
+	  if (next != field1)
+	    continue;
+
+	  fieldswap = field1;
+	  field1 = field2;
+	  field2 = fieldswap;
+	  defswap = def1;
+	  def1 = def2;
+	  def2 = defswap;
+	}
+
+      bb_for_def1 = gimple_bb (def1);
+      bb_for_def2 = gimple_bb (def2);
+
+      /* Check for proper alignment of the first field.  */
+      tree_offset1 = bit_position (field1);
+      tree_offset2 = bit_position (field2);
+      tree_size2 = DECL_SIZE (field2);
+
+      if (!tree_fits_uhwi_p (tree_offset1)
+	  || !tree_fits_uhwi_p (tree_offset2)
+	  || !tree_fits_uhwi_p (tree_size2))
+	continue;
+
+      offset1 = tree_to_uhwi (tree_offset1);
+      offset2 = tree_to_uhwi (tree_offset2);
+      size2 = tree_to_uhwi (tree_size2);
+      align1 = DECL_ALIGN (field1) % param_align_bits;
+
+      if (offset1 % BITS_PER_UNIT != 0)
+	continue;
+
+      /* For profitability, the two field references should fit within
+	 a single cache line.  */
+      if (align1 + offset2 - offset1 + size2 > param_align_bits)
+	continue;
+
+      /* The two expressions cannot be dependent upon vdefs defined
+	 in bb1/bb2.  */
+      if (local_mem_dependence (def1, bb_for_def1)
+	  || local_mem_dependence (def2, bb_for_def2))
+	continue;
+
+      /* The conditions are satisfied; hoist the loads from bb1 and bb2 into
+	 bb0.  We hoist the first one first so that a cache miss is handled
+         efficiently regardless of hardware cache-fill policy.  */
+      gsi2 = gsi_for_stmt (def1);
+      gsi_move_to_bb_end (&gsi2, bb0);
+      gsi2 = gsi_for_stmt (def2);
+      gsi_move_to_bb_end (&gsi2, bb0);
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	{
+	  fprintf (dump_file,
+		   "\nHoisting adjacent loads from %d and %d into %d: \n",
+		   bb_for_def1->index, bb_for_def2->index, bb0->index);
+	  print_gimple_stmt (dump_file, def1, 0, TDF_VOPS|TDF_MEMSYMS);
+	  print_gimple_stmt (dump_file, def2, 0, TDF_VOPS|TDF_MEMSYMS);
+	}
+    }
+}
+
+/* Determine whether we should attempt to hoist adjacent loads out of
+   diamond patterns in pass_phiopt.  Always hoist loads if
+   -fhoist-adjacent-loads is specified and the target machine has
+   both a conditional move instruction and a defined cache line size.  */
+
+static bool
+gate_hoist_loads (void)
+{
+  return (flag_hoist_adjacent_loads == 1
+	  && PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE)
+	  && HAVE_conditional_move);
+}
+
+/* Always do these optimizations if we have SSA
+   trees to work on.  */
+static bool
+gate_phiopt (void)
+{
+  return 1;
+}
+
+namespace {
+
+const pass_data pass_data_phiopt =
+{
+  GIMPLE_PASS, /* type */
+  "phiopt", /* name */
+  OPTGROUP_NONE, /* optinfo_flags */
+  true, /* has_gate */
+  true, /* has_execute */
+  TV_TREE_PHIOPT, /* tv_id */
+  ( PROP_cfg | PROP_ssa ), /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  ( TODO_verify_ssa | TODO_verify_flow
+    | TODO_verify_stmts ), /* todo_flags_finish */
+};
+
+class pass_phiopt : public gimple_opt_pass
+{
+public:
+  pass_phiopt (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_phiopt, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  opt_pass * clone () { return new pass_phiopt (m_ctxt); }
+  bool gate () { return gate_phiopt (); }
+  unsigned int execute () { return tree_ssa_phiopt (); }
+
+}; // class pass_phiopt
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_phiopt (gcc::context *ctxt)
+{
+  return new pass_phiopt (ctxt);
+}
+
+static bool
+gate_cselim (void)
+{
+  return flag_tree_cselim;
+}
+
+namespace {
+
+const pass_data pass_data_cselim =
+{
+  GIMPLE_PASS, /* type */
+  "cselim", /* name */
+  OPTGROUP_NONE, /* optinfo_flags */
+  true, /* has_gate */
+  true, /* has_execute */
+  TV_TREE_PHIOPT, /* tv_id */
+  ( PROP_cfg | PROP_ssa ), /* properties_required */
+  0, /* properties_provided */
+  0, /* properties_destroyed */
+  0, /* todo_flags_start */
+  ( TODO_verify_ssa | TODO_verify_flow
+    | TODO_verify_stmts ), /* todo_flags_finish */
+};
+
+class pass_cselim : public gimple_opt_pass
+{
+public:
+  pass_cselim (gcc::context *ctxt)
+    : gimple_opt_pass (pass_data_cselim, ctxt)
+  {}
+
+  /* opt_pass methods: */
+  bool gate () { return gate_cselim (); }
+  unsigned int execute () { return tree_ssa_cs_elim (); }
+
+}; // class pass_cselim
+
+} // anon namespace
+
+gimple_opt_pass *
+make_pass_cselim (gcc::context *ctxt)
+{
+  return new pass_cselim (ctxt);
+}