--- a/gcc/tree-ssa-dse.c	Sun Feb 07 18:28:00 2010 +0900
+++ b/gcc/tree-ssa-dse.c	Fri Feb 12 23:39:51 2010 +0900
@@ -45,7 +45,7 @@
    In our SSA + virtual operand world we use immediate uses of virtual
    operands to detect dead stores.  If a store's virtual definition
    is used precisely once by a later store to the same location which
-   post dominates the first store, then the first store is dead. 
+   post dominates the first store, then the first store is dead.
 
    The single use of the store's virtual definition ensures that
    there are no intervening aliased loads and the requirement that
@@ -56,7 +56,7 @@
    It may help to think of this as first moving the earlier store to
    the point immediately before the later store.  Again, the single
    use of the virtual definition and the post-dominance relationship
-   ensure that such movement would be safe.  Clearly if there are 
+   ensure that such movement would be safe.  Clearly if there are
    back to back stores, then the second is redundant.
 
    Reviewing section 10.7.2 in Morgan's "Building an Optimizing Compiler"
@@ -77,30 +77,20 @@
 };
 
 /* We allocate a bitmap-per-block for stores which are encountered
-   during the scan of that block.  This allows us to restore the 
+   during the scan of that block.  This allows us to restore the
    global bitmap of stores when we finish processing a block.  */
 struct dse_block_local_data
 {
   bitmap stores;
 };
 
-/* Basic blocks of the potentially dead store and the following
-   store, for memory_address_same.  */
-struct address_walk_data
-{
-  basic_block store1_bb, store2_bb;
-};
-
 static bool gate_dse (void);
 static unsigned int tree_ssa_dse (void);
 static void dse_initialize_block_local_data (struct dom_walk_data *,
 					     basic_block,
 					     bool);
-static void dse_optimize_stmt (struct dom_walk_data *,
-			       basic_block,
-			       gimple_stmt_iterator);
-static void dse_record_phis (struct dom_walk_data *, basic_block);
-static void dse_finalize_block (struct dom_walk_data *, basic_block);
+static void dse_enter_block (struct dom_walk_data *, basic_block);
+static void dse_leave_block (struct dom_walk_data *, basic_block);
 static void record_voperand_set (bitmap, bitmap *, unsigned int);
 
 /* Returns uid of statement STMT.  */
@@ -151,218 +141,112 @@
     }
 }
 
-/* Helper function for memory_address_same via walk_tree.  Returns
-   non-NULL if it finds an SSA_NAME which is part of the address,
-   such that the definition of the SSA_NAME post-dominates the store
-   we want to delete but not the store that we believe makes it
-   redundant.  This indicates that the address may change between
-   the two stores.  */
-
-static tree
-memory_ssa_name_same (tree *expr_p, int *walk_subtrees ATTRIBUTE_UNUSED,
-		      void *data)
-{
-  struct address_walk_data *walk_data = (struct address_walk_data *) data;
-  tree expr = *expr_p;
-  gimple def_stmt;
-  basic_block def_bb;
-
-  if (TREE_CODE (expr) != SSA_NAME)
-    return NULL_TREE;
-
-  /* If we've found a default definition, then there's no problem.  Both
-     stores will post-dominate it.  And def_bb will be NULL.  */
-  if (SSA_NAME_IS_DEFAULT_DEF (expr))
-    return NULL_TREE;
-
-  def_stmt = SSA_NAME_DEF_STMT (expr);
-  def_bb = gimple_bb (def_stmt);
-
-  /* DEF_STMT must dominate both stores.  So if it is in the same
-     basic block as one, it does not post-dominate that store.  */
-  if (walk_data->store1_bb != def_bb
-      && dominated_by_p (CDI_POST_DOMINATORS, walk_data->store1_bb, def_bb))
-    {
-      if (walk_data->store2_bb == def_bb
-	  || !dominated_by_p (CDI_POST_DOMINATORS, walk_data->store2_bb,
-			      def_bb))
-	/* Return non-NULL to stop the walk.  */
-	return *expr_p;
-    }
-
-  return NULL_TREE;
-}
-
-/* Return TRUE if the destination memory address in STORE1 and STORE2
-   might be modified after STORE1, before control reaches STORE2.  */
-
-static bool
-memory_address_same (gimple store1, gimple store2)
-{
-  struct address_walk_data walk_data;
-
-  walk_data.store1_bb = gimple_bb (store1);
-  walk_data.store2_bb = gimple_bb (store2);
-
-  return (walk_tree (gimple_assign_lhs_ptr (store1), memory_ssa_name_same,
-		     &walk_data, NULL)
-	  == NULL);
-}
-
-/* Return true if there is a stmt that kills the lhs of STMT and is in the
-   virtual def-use chain of STMT without a use in between the kill and STMT.
-   Returns false if no such stmt is found.
-   *FIRST_USE_P is set to the first use of the single virtual def of
-   STMT.  *USE_P is set to the vop killed by *USE_STMT.  */
-
-static bool
-get_kill_of_stmt_lhs (gimple stmt,
-		      use_operand_p * first_use_p,
- 		      use_operand_p * use_p, gimple * use_stmt)
-{
-  tree lhs;
-
-  gcc_assert (is_gimple_assign (stmt));
-
-  lhs = gimple_assign_lhs (stmt);
-
-  /* We now walk the chain of single uses of the single VDEFs.
-     We succeeded finding a kill if the lhs of the use stmt is
-     equal to the original lhs.  We can keep walking to the next
-     use if there are no possible uses of the original lhs in
-     the stmt.  */
-  do
-    {
-      tree use_lhs;
-      def_operand_p def_p;
-
-      /* The stmt must have a single VDEF.  */
-      def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_VDEF);
-      if (def_p == NULL_DEF_OPERAND_P)
-	return false;
-
-      /* Get the single immediate use of the def.  */
-      if (!single_imm_use (DEF_FROM_PTR (def_p), first_use_p, &stmt))
-	return false;
-      first_use_p = use_p;
-
-      /* If there are possible hidden uses, give up.  */
-      if (!gimple_assign_single_p (stmt)
-	  || (TREE_CODE (gimple_assign_rhs1 (stmt)) != SSA_NAME
-	      && !is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
-	return false;
-
-      /* If the use stmts lhs matches the original lhs we have
-	 found the kill, otherwise continue walking.  */
-      use_lhs = gimple_assign_lhs (stmt);
-      if (operand_equal_p (use_lhs, lhs, 0))
-	{
-	  *use_stmt = stmt;
-	  return true;
-	}
-    }
-  while (1);
-}
-
 /* A helper of dse_optimize_stmt.
-   Given a GIMPLE_ASSIGN in STMT, check that each VDEF has one
-   use, and that one use is another VDEF clobbering the first one.
-
+   Given a GIMPLE_ASSIGN in STMT, find a candidate statement *USE_STMT that
+   may prove STMT to be dead.
    Return TRUE if the above conditions are met, otherwise FALSE.  */
 
 static bool
-dse_possible_dead_store_p (gimple stmt,
-			   use_operand_p *first_use_p,
-			   use_operand_p *use_p,
-			   gimple *use_stmt,
-			   struct dse_global_data *dse_gd,
-			   struct dse_block_local_data *bd)
+dse_possible_dead_store_p (gimple stmt, gimple *use_stmt)
 {
-  ssa_op_iter op_iter;
-  bool fail = false;
-  def_operand_p var1;
-  vuse_vec_p vv;
-  tree defvar = NULL_TREE;
-  tree prev_defvar = NULL_TREE;
   gimple temp;
+  unsigned cnt = 0;
+
+  *use_stmt = NULL;
 
-  /* We want to verify that each virtual definition in STMT has
-     precisely one use and that all the virtual definitions are
-     used by the same single statement.  When complete, we
-     want USE_STMT to refer to the one statement which uses
-     all of the virtual definitions from STMT.  */
-  *use_stmt = NULL;
-  FOR_EACH_SSA_VDEF_OPERAND (var1, vv, stmt, op_iter)
+  /* Find the first dominated statement that clobbers (part of) the
+     memory stmt stores to with no intermediate statement that may use
+     part of the memory stmt stores.  That is, find a store that may
+     prove stmt to be a dead store.  */
+  temp = stmt;
+  do
     {
-      defvar = DEF_FROM_PTR (var1);
+      gimple prev, use_stmt;
+      imm_use_iterator ui;
+      bool fail = false;
+      tree defvar;
 
-      /* If this virtual def does not have precisely one use, then
-	 we will not be able to eliminate STMT.  */
-      if (!has_single_use (defvar))
-	{
-	  fail = true;
-	  break;
-	}
+      /* Limit stmt walking to be linear in the number of possibly
+         dead stores.  */
+      if (++cnt > 256)
+	return false;
 
-      /* Get the one and only immediate use of DEFVAR.  */
-      single_imm_use (defvar, use_p, &temp);
-      gcc_assert (*use_p != NULL_USE_OPERAND_P);
-      *first_use_p = *use_p;
-
-      /* ???  If we hit a GIMPLE_PHI we could skip to the PHI_RESULT uses.
-	 Don't bother to do that for now.  */
       if (gimple_code (temp) == GIMPLE_PHI)
+	defvar = PHI_RESULT (temp);
+      else
+	defvar = gimple_vdef (temp);
+      prev = temp;
+      temp = NULL;
+      FOR_EACH_IMM_USE_STMT (use_stmt, ui, defvar)
 	{
-	  fail = true;
-	  break;
-	}
-
-      /* In the case of memory partitions, we may get:
+	  cnt++;
 
-	   # MPT.764_162 = VDEF <MPT.764_161(D)>
-	   x = {};
-	   # MPT.764_167 = VDEF <MPT.764_162>
-	   y = {};
-
-	   So we must make sure we're talking about the same LHS.
-      */
-      if (is_gimple_assign (temp))
-	{
-	  tree base1 = get_base_address (gimple_assign_lhs (stmt));
-	  tree base2 = get_base_address (gimple_assign_lhs (temp));
-
-	  while (base1 && INDIRECT_REF_P (base1))
-	    base1 = TREE_OPERAND (base1, 0);
-	  while (base2 && INDIRECT_REF_P (base2))
-	    base2 = TREE_OPERAND (base2, 0);
-
-	  if (base1 != base2)
+	  /* In simple cases we can look through PHI nodes, but we
+	     have to be careful with loops and with memory references
+	     containing operands that are also operands of PHI nodes.
+	     See gcc.c-torture/execute/20051110-*.c.  */
+	  if (gimple_code (use_stmt) == GIMPLE_PHI)
+	    {
+	      if (temp
+		  /* We can look through PHIs to post-dominated regions
+		     without worrying if the use not also dominates prev
+		     (in which case it would be a loop PHI with the use
+		     in a latch block).  */
+		  || gimple_bb (prev) == gimple_bb (use_stmt)
+		  || !dominated_by_p (CDI_POST_DOMINATORS,
+				      gimple_bb (prev), gimple_bb (use_stmt))
+		  || dominated_by_p (CDI_DOMINATORS,
+				     gimple_bb (prev), gimple_bb (use_stmt)))
+		{
+		  fail = true;
+		  BREAK_FROM_IMM_USE_STMT (ui);
+		}
+	      temp = use_stmt;
+	    }
+	  /* If the statement is a use the store is not dead.  */
+	  else if (ref_maybe_used_by_stmt_p (use_stmt,
+					     gimple_assign_lhs (stmt)))
 	    {
 	      fail = true;
-	      break;
+	      BREAK_FROM_IMM_USE_STMT (ui);
+	    }
+	  /* If this is a store, remember it or bail out if we have
+	     multiple ones (the will be in different CFG parts then).  */
+	  else if (gimple_vdef (use_stmt))
+	    {
+	      if (temp)
+		{
+		  fail = true;
+		  BREAK_FROM_IMM_USE_STMT (ui);
+		}
+	      temp = use_stmt;
 	    }
 	}
 
-      /* If the immediate use of DEF_VAR is not the same as the
-	 previously find immediate uses, then we will not be able
-	 to eliminate STMT.  */
-      if (*use_stmt == NULL)
+      if (fail)
+	return false;
+
+      /* If we didn't find any definition this means the store is dead
+         if it isn't a store to global reachable memory.  In this case
+	 just pretend the stmt makes itself dead.  Otherwise fail.  */
+      if (!temp)
 	{
-	  *use_stmt = temp;
-	  prev_defvar = defvar;
-	}
-      else if (temp != *use_stmt)
-	{
-	  fail = true;
+	  if (is_hidden_global_store (stmt))
+	    return false;
+
+	  temp = stmt;
 	  break;
 	}
     }
+  /* We deliberately stop on clobbering statements and not only on
+     killing ones to make walking cheaper.  Otherwise we can just
+     continue walking until both stores have equal reference trees.  */
+  while (!stmt_may_clobber_ref_p (temp, gimple_assign_lhs (stmt)));
 
-  if (fail)
-    {
-      record_voperand_set (dse_gd->stores, &bd->stores, gimple_uid (stmt));
-      return false;
-    }
+  if (!is_gimple_assign (temp))
+    return false;
+
+  *use_stmt = temp;
 
   return true;
 }
@@ -380,20 +264,15 @@
    post dominates the first store, then the first store is dead.  */
 
 static void
-dse_optimize_stmt (struct dom_walk_data *walk_data,
-		   basic_block bb ATTRIBUTE_UNUSED,
+dse_optimize_stmt (struct dse_global_data *dse_gd,
+		   struct dse_block_local_data *bd,
 		   gimple_stmt_iterator gsi)
 {
-  struct dse_block_local_data *bd
-    = (struct dse_block_local_data *)
-	VEC_last (void_p, walk_data->block_data_stack);
-  struct dse_global_data *dse_gd
-    = (struct dse_global_data *) walk_data->global_data;
   gimple stmt = gsi_stmt (gsi);
 
   /* If this statement has no virtual defs, then there is nothing
      to do.  */
-  if (ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF))
+  if (!gimple_vdef (stmt))
     return;
 
   /* We know we have virtual definitions.  If this is a GIMPLE_ASSIGN
@@ -406,51 +285,21 @@
 
   if (is_gimple_assign (stmt))
     {
-      use_operand_p first_use_p = NULL_USE_OPERAND_P;
-      use_operand_p use_p = NULL;
       gimple use_stmt;
 
-      if (!dse_possible_dead_store_p (stmt, &first_use_p, &use_p, &use_stmt, 
-				      dse_gd, bd))
-	return;
+      record_voperand_set (dse_gd->stores, &bd->stores, gimple_uid (stmt));
 
-      /* If we have precisely one immediate use at this point, then we may
-	 have found redundant store.  Make sure that the stores are to
-	 the same memory location.  This includes checking that any
-	 SSA-form variables in the address will have the same values.  */
-      if (use_p != NULL_USE_OPERAND_P
-          && bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
-          && !operand_equal_p (gimple_assign_lhs (stmt),
-                               gimple_assign_lhs (use_stmt), 0)
-          && memory_address_same (stmt, use_stmt))
-        {
-          /* If we have precisely one immediate use at this point, but
-             the stores are not to the same memory location then walk the
-             virtual def-use chain to get the stmt which stores to that same
-             memory location.  */
-          if (!get_kill_of_stmt_lhs (stmt, &first_use_p, &use_p, &use_stmt))
-            {
-              record_voperand_set (dse_gd->stores, &bd->stores, 
-				   gimple_uid (stmt));
-              return;
-            }
-        }
+      if (!dse_possible_dead_store_p (stmt, &use_stmt))
+	return;
 
       /* If we have precisely one immediate use at this point and the
 	 stores are to the same memory location or there is a chain of
 	 virtual uses from stmt and the stmt which stores to that same
 	 memory location, then we may have found redundant store.  */
-      if (use_p != NULL_USE_OPERAND_P
-	  && bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
+      if (bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
 	  && operand_equal_p (gimple_assign_lhs (stmt),
-			      gimple_assign_lhs (use_stmt), 0)
-	  && memory_address_same (stmt, use_stmt))
+			      gimple_assign_lhs (use_stmt), 0))
 	{
-	  ssa_op_iter op_iter;
-	  def_operand_p var1;
-	  vuse_vec_p vv;
-	  tree stmt_lhs;
-
 	  /* If use_stmt is or might be a nop assignment, e.g. for
 	     struct { ... } S a, b, *p; ...
 	     b = a; b = b;
@@ -462,14 +311,14 @@
 	     *p = *u; *p = *v; where p might be v, then USE_STMT
 	     acts as a use as well as definition, so store in STMT
 	     is not dead.  */
-	  if (gimple_loaded_syms (use_stmt)
-	      && bitmap_intersect_p (gimple_loaded_syms (use_stmt),
-				     gimple_stored_syms (use_stmt)))
-	    {
-              record_voperand_set (dse_gd->stores, &bd->stores, 
-				   gimple_uid (stmt));
-	      return;
-	    }
+	  if (stmt != use_stmt
+	      && !is_gimple_reg (gimple_assign_rhs1 (use_stmt))
+	      && !is_gimple_min_invariant (gimple_assign_rhs1 (use_stmt))
+	      /* ???  Should {} be invariant?  */
+	      && gimple_assign_rhs_code (use_stmt) != CONSTRUCTOR
+	      && refs_may_alias_p (gimple_assign_lhs (use_stmt),
+				   gimple_assign_rhs1 (use_stmt)))
+	    return;
 
 	  if (dump_file && (dump_flags & TDF_DETAILS))
             {
@@ -479,21 +328,7 @@
             }
 
 	  /* Then we need to fix the operand of the consuming stmt.  */
-	  stmt_lhs = USE_FROM_PTR (first_use_p);
-	  FOR_EACH_SSA_VDEF_OPERAND (var1, vv, stmt, op_iter)
-	    {
-	      tree usevar;
-	      gimple temp;
-
-	      single_imm_use (DEF_FROM_PTR (var1), &use_p, &temp);
-	      gcc_assert (VUSE_VECT_NUM_ELEM (*vv) == 1);
-	      usevar = VUSE_ELEMENT_VAR (*vv, 0);
-	      SET_USE (use_p, usevar);
-
-	      /* Make sure we propagate the ABNORMAL bit setting.  */
-	      if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (stmt_lhs))
-		SSA_NAME_OCCURS_IN_ABNORMAL_PHI (usevar) = 1;
-	    }
+	  unlink_stmt_vdef (stmt);
 
 	  /* Remove the dead store.  */
 	  gsi_remove (&gsi, true);
@@ -502,35 +337,39 @@
 	     SSA_NAME manager.  */
 	  release_defs (stmt);
 	}
-
-      record_voperand_set (dse_gd->stores, &bd->stores, gimple_uid (stmt));
     }
 }
 
 /* Record that we have seen the PHIs at the start of BB which correspond
    to virtual operands.  */
 static void
-dse_record_phis (struct dom_walk_data *walk_data, basic_block bb)
+dse_record_phi (struct dse_global_data *dse_gd,
+		struct dse_block_local_data *bd,
+		gimple phi)
+{
+  if (!is_gimple_reg (gimple_phi_result (phi)))
+    record_voperand_set (dse_gd->stores, &bd->stores, get_stmt_uid (phi));
+}
+
+static void
+dse_enter_block (struct dom_walk_data *walk_data, basic_block bb)
 {
   struct dse_block_local_data *bd
     = (struct dse_block_local_data *)
 	VEC_last (void_p, walk_data->block_data_stack);
   struct dse_global_data *dse_gd
     = (struct dse_global_data *) walk_data->global_data;
-  gimple phi;
   gimple_stmt_iterator gsi;
 
+  for (gsi = gsi_last (bb_seq (bb)); !gsi_end_p (gsi); gsi_prev (&gsi))
+    dse_optimize_stmt (dse_gd, bd, gsi);
   for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
-    {
-      phi = gsi_stmt (gsi);
-      if (!is_gimple_reg (gimple_phi_result (phi)))
-	record_voperand_set (dse_gd->stores, &bd->stores, get_stmt_uid (phi));
-    }
+    dse_record_phi (dse_gd, bd, gsi_stmt (gsi));
 }
 
 static void
-dse_finalize_block (struct dom_walk_data *walk_data,
-		    basic_block bb ATTRIBUTE_UNUSED)
+dse_leave_block (struct dom_walk_data *walk_data,
+		 basic_block bb ATTRIBUTE_UNUSED)
 {
   struct dse_block_local_data *bd
     = (struct dse_block_local_data *)
@@ -564,19 +403,14 @@
      this pass could be seen as an extension of DCE which needs post
      dominators.  */
   calculate_dominance_info (CDI_POST_DOMINATORS);
+  calculate_dominance_info (CDI_DOMINATORS);
 
   /* Dead store elimination is fundamentally a walk of the post-dominator
      tree and a backwards walk of statements within each block.  */
-  walk_data.walk_stmts_backward = true;
   walk_data.dom_direction = CDI_POST_DOMINATORS;
   walk_data.initialize_block_local_data = dse_initialize_block_local_data;
-  walk_data.before_dom_children_before_stmts = NULL;
-  walk_data.before_dom_children_walk_stmts = dse_optimize_stmt;
-  walk_data.before_dom_children_after_stmts = dse_record_phis;
-  walk_data.after_dom_children_before_stmts = NULL;
-  walk_data.after_dom_children_walk_stmts = NULL;
-  walk_data.after_dom_children_after_stmts = dse_finalize_block;
-  walk_data.interesting_blocks = NULL;
+  walk_data.before_dom_children = dse_enter_block;
+  walk_data.after_dom_children = dse_leave_block;
 
   walk_data.block_local_data_size = sizeof (struct dse_block_local_data);
 
@@ -607,7 +441,7 @@
   return flag_tree_dse != 0;
 }
 
-struct gimple_opt_pass pass_dse = 
+struct gimple_opt_pass pass_dse =
 {
  {
   GIMPLE_PASS,
@@ -618,9 +452,7 @@
   NULL,				/* next */
   0,				/* static_pass_number */
   TV_TREE_DSE,			/* tv_id */
-  PROP_cfg
-    | PROP_ssa
-    | PROP_alias,		/* properties_required */
+  PROP_cfg | PROP_ssa,		/* properties_required */
   0,				/* properties_provided */
   0,				/* properties_destroyed */
   0,				/* todo_flags_start */
@@ -630,153 +462,3 @@
  }
 };
 
-/* A very simple dead store pass eliminating write only local variables.
-   The pass does not require alias information and thus can be run before
-   inlining to quickly eliminate artifacts of some common C++ constructs.  */
-
-static unsigned int
-execute_simple_dse (void)
-{
-  gimple_stmt_iterator gsi;
-  basic_block bb;
-  bitmap variables_loaded = BITMAP_ALLOC (NULL);
-  unsigned int todo = 0;
-
-  /* Collect into VARIABLES LOADED all variables that are read in function
-     body.  */
-  FOR_EACH_BB (bb)
-    for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
-
-      if (gimple_loaded_syms (gsi_stmt (gsi)))
-	bitmap_ior_into (variables_loaded,
-			 gimple_loaded_syms (gsi_stmt (gsi)));
-
-  /* Look for statements writing into the write only variables.
-     And try to remove them.  */
-
-  FOR_EACH_BB (bb)
-    for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
-      {
-	gimple stmt = gsi_stmt (gsi);
-        tree op;
-	bool removed = false;
-        ssa_op_iter iter;
-	tree size;
-
-	if (is_gimple_assign (stmt)
-	    && AGGREGATE_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt)))
-	    && (size = lang_hooks.expr_size (gimple_assign_lhs (stmt)))
-	    && integer_zerop (size))
-	  {
-	    if (dump_file && (dump_flags & TDF_DETAILS))
-	      {
-		fprintf (dump_file, "  Deleted zero-sized store '");
-		print_gimple_stmt (dump_file, stmt, 0, dump_flags);
-		fprintf (dump_file, "'\n");
-	      }
-	    removed = true;
-	    gsi_remove (&gsi, true);
-	    todo |= TODO_cleanup_cfg;
-	  }
-	else if (gimple_stored_syms (stmt)
-		 && !bitmap_empty_p (gimple_stored_syms (stmt))
-		 && (is_gimple_assign (stmt)
-		     || (is_gimple_call (stmt)
-			 && gimple_call_lhs (stmt)))
-		 && !bitmap_intersect_p (gimple_stored_syms (stmt),
-					 variables_loaded))
-	  {
-	    unsigned int i;
-	    bitmap_iterator bi;
-	    bool dead = true;
-
-	    /* See if STMT only stores to write-only variables and
-	       verify that there are no volatile operands.  tree-ssa-operands
-	       sets has_volatile_ops flag for all statements involving
-	       reads and writes when aliases are not built to prevent passes
-	       from removing them as dead.  The flag thus has no use for us
-	       and we need to look into all operands.  */
-	      
-	    EXECUTE_IF_SET_IN_BITMAP (gimple_stored_syms (stmt), 0, i, bi)
-	      {
-		tree var = referenced_var_lookup (i);
-		if (TREE_ADDRESSABLE (var)
-		    || is_global_var (var)
-		    || TREE_THIS_VOLATILE (var))
-		  dead = false;
-	      }
-
-	    if (dead && gimple_loaded_syms (stmt))
-	      EXECUTE_IF_SET_IN_BITMAP (gimple_loaded_syms (stmt), 0, i, bi)
-		if (TREE_THIS_VOLATILE (referenced_var_lookup (i)))
-		  dead = false;
-
-	    if (dead)
-	      FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_OPERANDS)
-		if (TREE_THIS_VOLATILE (op))
-		  dead = false;
-
-	    /* Look for possible occurrence var = indirect_ref (...) where
-	       indirect_ref itself is volatile.  */
-
-	    if (dead && is_gimple_assign (stmt)
-	        && TREE_THIS_VOLATILE (gimple_assign_rhs1 (stmt)))
-	      dead = false;
-
-	    if (dead)
-	      {
-		/* When LHS of var = call (); is dead, simplify it into
-		   call (); saving one operand.  */
-                if (is_gimple_call (stmt)
-                    && gimple_has_side_effects (stmt))
-		  {
-		    if (dump_file && (dump_flags & TDF_DETAILS))
-		      {
-			fprintf (dump_file, "Deleted LHS of call: ");
-			print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
-			fprintf (dump_file, "\n");
-		      }
-		    push_stmt_changes (gsi_stmt_ptr (&gsi));
-                    gimple_call_set_lhs (stmt, NULL);
-		    pop_stmt_changes (gsi_stmt_ptr (&gsi));
-		  }
-		else
-		  {
-		    if (dump_file && (dump_flags & TDF_DETAILS))
-		      {
-			fprintf (dump_file, "  Deleted dead store '");
-			print_gimple_stmt (dump_file, stmt, 0, dump_flags);
-			fprintf (dump_file, "'\n");
-		      }
-		    removed = true;
-		    gsi_remove (&gsi, true);
-		    todo |= TODO_cleanup_cfg;
-		  }
-		todo |= TODO_remove_unused_locals | TODO_ggc_collect;
-	      }
-	  }
-	if (!removed)
-	  gsi_next (&gsi);
-      }
-  BITMAP_FREE (variables_loaded);
-  return todo;
-}
-
-struct gimple_opt_pass pass_simple_dse =
-{
- {
-  GIMPLE_PASS,
-  "sdse",				/* name */
-  NULL,					/* gate */
-  execute_simple_dse,			/* execute */
-  NULL,					/* sub */
-  NULL,					/* next */
-  0,					/* static_pass_number */
-  0,					/* tv_id */
-  PROP_ssa,				/* properties_required */
-  0,					/* properties_provided */
-  0,					/* properties_destroyed */
-  0,					/* todo_flags_start */
-  TODO_dump_func          	        /* todo_flags_finish */
- }
-};