tree-ssa-pre.c (eliminate_dom_walker::before_dom_children): Rewrite to propagate…

tree-ssa-pre.c (eliminate_dom_walker::before_dom_children): Rewrite to propagate the VN result into all uses where possible and to remove...

2014-06-13  Richard Biener  <rguenther@suse.de>

	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
	Rewrite to propagate the VN result into all uses where
	possible and to remove stmts becoming dead because of that.
	(eliminate): Generalize stmt removal handling, remove in
	reverse dominator order to support proper debug stmt
	generation.  Update stmts before removing stmts.
	* tree-ssa-propagate.c (propagate_tree_value): Remove
	bogus assert.

	* c-c++-common/pr46562-2.c: Adjust.
	* g++.dg/tree-ssa/pr8781.C: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-24.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-25.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-32.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-39.c: Likewise.
	* gcc.dg/tree-ssa/ssa-pre-16.c: Likewise.

From-SVN: r211625

gcc/ChangeLog

+2014-06-13  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
+	Rewrite to propagate the VN result into all uses where
+	possible and to remove stmts becoming dead because of that.
+	(eliminate): Generalize stmt removal handling, remove in
+	reverse dominator order to support proper debug stmt
+	generation.  Update stmts before removing stmts.
+	* tree-ssa-propagate.c (propagate_tree_value): Remove
+	bogus assert.
+
 2014-06-13  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	PR tree-optimization/61375

gcc/testsuite/ChangeLog

+2014-06-13  Richard Biener  <rguenther@suse.de>
+
+	* c-c++-common/pr46562-2.c: Adjust.
+	* g++.dg/tree-ssa/pr8781.C: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-24.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-25.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-32.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-39.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-pre-16.c: Likewise.
+
 2014-06-13  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
 	PR tree-optimization/61375

gcc/testsuite/c-c++-common/pr46562-2.c

@@ -9,5 +9,5 @@ int foo(void)
   return *p;
 }
 
-/* { dg-final { scan-tree-dump "= 0;" "fre1" } } */
+/* { dg-final { scan-tree-dump "return 0;" "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/g++.dg/tree-ssa/pr8781.C

 /* { dg-do compile } */
-/* { dg-options "-O -fno-tree-sra -fdump-tree-fre1-details" } */
+/* { dg-options "-O -fno-tree-sra -fdump-tree-fre1" } */
 
 int f();
 
@@ -24,5 +24,5 @@ int x()
 
 /* We should optimize this to a direct call.  */
 
-/* { dg-final { scan-tree-dump "converting indirect call to function int f()" "fre1" } } */
+/* { dg-final { scan-tree-dump-times "= f \\(\\);" 1 "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-24.c

@@ -30,5 +30,5 @@ int bazzoo (void)
   return b.i;
 }
 
-/* { dg-final { scan-tree-dump-times "= 0;" 5 "fre1" } } */
+/* { dg-final { scan-tree-dump-times "return 0;" 4 "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-25.c

@@ -14,5 +14,5 @@ int foo (struct X *p)
 
 /* We should optimize this to return 0.  */
 
-/* { dg-final { scan-tree-dump "= 0;" "fre1" } } */
+/* { dg-final { scan-tree-dump "return 0;" "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-32.c

@@ -23,6 +23,6 @@ bar (_Complex float x)
   return z;
 } 
 
-/* We should CSE all the way to replace the final assignment to z with x.  */
-/* { dg-final { scan-tree-dump-times "with x_1\\\(D\\\) in z" 3 "fre1" } } */
+/* We should CSE all the way to replace the return value with x.  */
+/* { dg-final { scan-tree-dump-times "return x_\\d\+\\(D\\);" 2 "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-39.c

@@ -15,5 +15,5 @@ int foo (int i)
 
 /* We should be able to value-number the final assignment to k to 1.  */
 
-/* { dg-final { scan-tree-dump "k_. = 1;" "fre1" } } */
+/* { dg-final { scan-tree-dump "return 1;" "fre1" } } */
 /* { dg-final { cleanup-tree-dump "fre1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-16.c

@@ -11,5 +11,5 @@ int foo(int k, int *x)
   }  while (++j<k);
   return res;
 }
-/* { dg-final { scan-tree-dump-times "Eliminated: 1" 1 "pre"} } */
+/* { dg-final { scan-tree-dump-times "Eliminated: 2" 1 "pre"} } */
 /* { dg-final { cleanup-tree-dump "pre" } } */

gcc/tree-ssa-pre.c

@@ -4012,120 +4012,93 @@ eliminate_dom_walker::before_dom_children (basic_block b)
   /* Mark new bb.  */
   el_avail_stack.safe_push (NULL_TREE);
 
-  /* If this block is not reachable do nothing.  */
-  edge_iterator ei;
-  edge e;
-  FOR_EACH_EDGE (e, ei, b->preds)
-    if (e->flags & EDGE_EXECUTABLE)
-      break;
-  if (!e)
-    return;
+  /* ???  If we do nothing for unreachable blocks then this will confuse
+     tailmerging.  Eventually we can reduce its reliance on SCCVN now
+     that we fully copy/constant-propagate (most) things.  */
 
   for (gsi = gsi_start_phis (b); !gsi_end_p (gsi);)
     {
-      gimple stmt, phi = gsi_stmt (gsi);
-      tree sprime = NULL_TREE, res = PHI_RESULT (phi);
-      gimple_stmt_iterator gsi2;
-
-      /* We want to perform redundant PHI elimination.  Do so by
-	 replacing the PHI with a single copy if possible.
-	 Do not touch inserted, single-argument or virtual PHIs.  */
-      if (gimple_phi_num_args (phi) == 1
-	  || virtual_operand_p (res))
-	{
-	  gsi_next (&gsi);
-	  continue;
-	}
+      gimple phi = gsi_stmt (gsi);
+      tree res = PHI_RESULT (phi);
 
-      sprime = eliminate_avail (res);
-      if (!sprime
-	  || sprime == res)
+      if (virtual_operand_p (res))
 	{
-	  eliminate_push_avail (res);
 	  gsi_next (&gsi);
 	  continue;
 	}
-      else if (is_gimple_min_invariant (sprime))
-	{
-	  if (!useless_type_conversion_p (TREE_TYPE (res),
-					  TREE_TYPE (sprime)))
-	    sprime = fold_convert (TREE_TYPE (res), sprime);
-	}
 
-      if (dump_file && (dump_flags & TDF_DETAILS))
+      tree sprime = eliminate_avail (res);
+      if (sprime
+	  && sprime != res)
 	{
-	  fprintf (dump_file, "Replaced redundant PHI node defining ");
-	  print_generic_expr (dump_file, res, 0);
-	  fprintf (dump_file, " with ");
-	  print_generic_expr (dump_file, sprime, 0);
-	  fprintf (dump_file, "\n");
-	}
-
-      remove_phi_node (&gsi, false);
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "Replaced redundant PHI node defining ");
+	      print_generic_expr (dump_file, res, 0);
+	      fprintf (dump_file, " with ");
+	      print_generic_expr (dump_file, sprime, 0);
+	      fprintf (dump_file, "\n");
+	    }
 
-      if (inserted_exprs
-	  && !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res))
-	  && TREE_CODE (sprime) == SSA_NAME)
-	gimple_set_plf (SSA_NAME_DEF_STMT (sprime), NECESSARY, true);
-
-      if (!useless_type_conversion_p (TREE_TYPE (res), TREE_TYPE (sprime)))
-	sprime = fold_convert (TREE_TYPE (res), sprime);
-      stmt = gimple_build_assign (res, sprime);
-      gimple_set_plf (stmt, NECESSARY, gimple_plf (phi, NECESSARY));
-
-      gsi2 = gsi_after_labels (b);
-      gsi_insert_before (&gsi2, stmt, GSI_NEW_STMT);
-      /* Queue the copy for eventual removal.  */
-      el_to_remove.safe_push (stmt);
-      /* If we inserted this PHI node ourself, it's not an elimination.  */
-      if (inserted_exprs
-	  && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res)))
-	pre_stats.phis--;
-      else
-	pre_stats.eliminations++;
-    }
+	  /* If we inserted this PHI node ourself, it's not an elimination.  */
+	  if (inserted_exprs
+	      && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res)))
+	    pre_stats.phis--;
+	  else
+	    pre_stats.eliminations++;
 
-  for (gsi = gsi_start_bb (b); !gsi_end_p (gsi); gsi_next (&gsi))
-    {
-      tree lhs = NULL_TREE;
-      tree rhs = NULL_TREE;
+	  /* If we will propagate into all uses don't bother to do
+	     anything.  */
+	  if (may_propagate_copy (res, sprime))
+	    {
+	      /* Mark the PHI for removal.  */
+	      el_to_remove.safe_push (phi);
+	      gsi_next (&gsi);
+	      continue;
+	    }
 
-      stmt = gsi_stmt (gsi);
+	  remove_phi_node (&gsi, false);
 
-      if (gimple_has_lhs (stmt))
-	lhs = gimple_get_lhs (stmt);
+	  if (inserted_exprs
+	      && !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (res))
+	      && TREE_CODE (sprime) == SSA_NAME)
+	    gimple_set_plf (SSA_NAME_DEF_STMT (sprime), NECESSARY, true);
 
-      if (gimple_assign_single_p (stmt))
-	rhs = gimple_assign_rhs1 (stmt);
+	  if (!useless_type_conversion_p (TREE_TYPE (res), TREE_TYPE (sprime)))
+	    sprime = fold_convert (TREE_TYPE (res), sprime);
+	  gimple stmt = gimple_build_assign (res, sprime);
+	  /* ???  It cannot yet be necessary (DOM walk).  */
+	  gimple_set_plf (stmt, NECESSARY, gimple_plf (phi, NECESSARY));
 
-      /* Lookup the RHS of the expression, see if we have an
-	 available computation for it.  If so, replace the RHS with
-	 the available computation.  */
-      if (gimple_has_lhs (stmt)
-	  && TREE_CODE (lhs) == SSA_NAME
-	  && !gimple_has_volatile_ops  (stmt))
-	{
-	  tree sprime;
-	  gimple orig_stmt = stmt;
+	  gimple_stmt_iterator gsi2 = gsi_after_labels (b);
+	  gsi_insert_before (&gsi2, stmt, GSI_NEW_STMT);
+	  continue;
+	}
 
-	  sprime = eliminate_avail (lhs);
-	  /* If there is no usable leader mark lhs as leader for its value.  */
-	  if (!sprime)
-	    eliminate_push_avail (lhs);
+      eliminate_push_avail (res);
+      gsi_next (&gsi);
+    }
 
+  for (gsi = gsi_start_bb (b); !gsi_end_p (gsi); gsi_next (&gsi))
+    {
+      tree sprime = NULL_TREE;
+      stmt = gsi_stmt (gsi);
+      tree lhs = gimple_get_lhs (stmt);
+      if (lhs && TREE_CODE (lhs) == SSA_NAME
+	  && !gimple_has_volatile_ops (stmt)
 	  /* See PR43491.  Do not replace a global register variable when
 	     it is a the RHS of an assignment.  Do replace local register
 	     variables since gcc does not guarantee a local variable will
 	     be allocated in register.
-	     Do not perform copy propagation or undo constant propagation.  */
-	  if (gimple_assign_single_p (stmt)
-	      && (TREE_CODE (rhs) == SSA_NAME
-		  || is_gimple_min_invariant (rhs)
-		  || (TREE_CODE (rhs) == VAR_DECL
-		      && is_global_var (rhs)
-		      && DECL_HARD_REGISTER (rhs))))
-	    continue;
-
+	     ???  The fix isn't effective here.  This should instead
+	     be ensured by not value-numbering them the same but treating
+	     them like volatiles?  */
+	  && !(gimple_assign_single_p (stmt)
+	       && (TREE_CODE (gimple_assign_rhs1 (stmt)) == VAR_DECL
+		   && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt))
+		   && is_global_var (gimple_assign_rhs1 (stmt)))))
+	{
+	  sprime = eliminate_avail (lhs);
 	  if (!sprime)
 	    {
 	      /* If there is no existing usable leader but SCCVN thinks
@@ -4139,107 +4112,128 @@ eliminate_dom_walker::before_dom_children (basic_block b)
 		  && (sprime = eliminate_insert (&gsi, val)) != NULL_TREE)
 		eliminate_push_avail (sprime);
 	    }
-	  else if (is_gimple_min_invariant (sprime))
-	    {
-	      /* If there is no existing leader but SCCVN knows this
-		 value is constant, use that constant.  */
-	      if (!useless_type_conversion_p (TREE_TYPE (lhs),
-					      TREE_TYPE (sprime)))
-		sprime = fold_convert (TREE_TYPE (lhs), sprime);
-
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		{
-		  fprintf (dump_file, "Replaced ");
-		  print_gimple_expr (dump_file, stmt, 0, 0);
-		  fprintf (dump_file, " with ");
-		  print_generic_expr (dump_file, sprime, 0);
-		  fprintf (dump_file, " in ");
-		  print_gimple_stmt (dump_file, stmt, 0, 0);
-		}
-	      pre_stats.eliminations++;
-
-	      tree vdef = gimple_vdef (stmt);
-	      tree vuse = gimple_vuse (stmt);
-	      propagate_tree_value_into_stmt (&gsi, sprime);
-	      stmt = gsi_stmt (gsi);
-	      update_stmt (stmt);
-	      if (vdef != gimple_vdef (stmt))
-		VN_INFO (vdef)->valnum = vuse;
 
-	      /* If we removed EH side-effects from the statement, clean
-		 its EH information.  */
-	      if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
+	  /* If this now constitutes a copy duplicate points-to
+	     and range info appropriately.  This is especially
+	     important for inserted code.  See tree-ssa-copy.c
+	     for similar code.  */
+	  if (sprime
+	      && TREE_CODE (sprime) == SSA_NAME)
+	    {
+	      basic_block sprime_b = gimple_bb (SSA_NAME_DEF_STMT (sprime));
+	      if (POINTER_TYPE_P (TREE_TYPE (lhs))
+		  && SSA_NAME_PTR_INFO (lhs)
+		  && !SSA_NAME_PTR_INFO (sprime))
 		{
-		  bitmap_set_bit (need_eh_cleanup,
-				  gimple_bb (stmt)->index);
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    fprintf (dump_file, "  Removed EH side-effects.\n");
+		  duplicate_ssa_name_ptr_info (sprime,
+					       SSA_NAME_PTR_INFO (lhs));
+		  if (b != sprime_b)
+		    mark_ptr_info_alignment_unknown
+			(SSA_NAME_PTR_INFO (sprime));
 		}
-	      continue;
+	      else if (!POINTER_TYPE_P (TREE_TYPE (lhs))
+		       && SSA_NAME_RANGE_INFO (lhs)
+		       && !SSA_NAME_RANGE_INFO (sprime)
+		       && b == sprime_b)
+		duplicate_ssa_name_range_info (sprime,
+					       SSA_NAME_RANGE_TYPE (lhs),
+					       SSA_NAME_RANGE_INFO (lhs));
 	    }
 
+	  /* Inhibit the use of an inserted PHI on a loop header when
+	     the address of the memory reference is a simple induction
+	     variable.  In other cases the vectorizer won't do anything
+	     anyway (either it's loop invariant or a complicated
+	     expression).  */
 	  if (sprime
-	      && sprime != lhs
-	      && (rhs == NULL_TREE
-		  || TREE_CODE (rhs) != SSA_NAME
-		  || may_propagate_copy (rhs, sprime)))
+	      && TREE_CODE (sprime) == SSA_NAME
+	      && do_pre
+	      && flag_tree_loop_vectorize
+	      && loop_outer (b->loop_father)
+	      && has_zero_uses (sprime)
+	      && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime))
+	      && gimple_assign_load_p (stmt))
 	    {
-	      bool can_make_abnormal_goto
-		  = is_gimple_call (stmt)
-		  && stmt_can_make_abnormal_goto (stmt);
-
-	      gcc_assert (sprime != rhs);
-
-	      /* Inhibit the use of an inserted PHI on a loop header when
-		 the address of the memory reference is a simple induction
-		 variable.  In other cases the vectorizer won't do anything
-		 anyway (either it's loop invariant or a complicated
-		 expression).  */
-	      if (do_pre
-		  && flag_tree_loop_vectorize
-		  && gimple_assign_single_p (stmt)
-		  && TREE_CODE (sprime) == SSA_NAME
-		  && loop_outer (b->loop_father))
+	      gimple def_stmt = SSA_NAME_DEF_STMT (sprime);
+	      basic_block def_bb = gimple_bb (def_stmt);
+	      if (gimple_code (def_stmt) == GIMPLE_PHI
+		  && b->loop_father->header == def_bb)
 		{
-		  gimple def_stmt = SSA_NAME_DEF_STMT (sprime);
-		  basic_block def_bb = gimple_bb (def_stmt);
-		  if (gimple_code (def_stmt) == GIMPLE_PHI
-		      && b->loop_father->header == def_bb
-		      && has_zero_uses (sprime))
+		  ssa_op_iter iter;
+		  tree op;
+		  bool found = false;
+		  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
 		    {
-		      ssa_op_iter iter;
-		      tree op;
-		      bool found = false;
-		      FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
+		      affine_iv iv;
+		      def_bb = gimple_bb (SSA_NAME_DEF_STMT (op));
+		      if (def_bb
+			  && flow_bb_inside_loop_p (b->loop_father, def_bb)
+			  && simple_iv (b->loop_father,
+					b->loop_father, op, &iv, true))
 			{
-			  affine_iv iv;
-			  def_bb = gimple_bb (SSA_NAME_DEF_STMT (op));
-			  if (def_bb
-			      && flow_bb_inside_loop_p (b->loop_father,
-							def_bb)
-			      && simple_iv (b->loop_father,
-					    b->loop_father, op, &iv, true))
-			    {
-			      found = true;
-			      break;
-			    }
+			  found = true;
+			  break;
 			}
-		      if (found)
+		    }
+		  if (found)
+		    {
+		      if (dump_file && (dump_flags & TDF_DETAILS))
 			{
-			  if (dump_file && (dump_flags & TDF_DETAILS))
-			    {
-			      fprintf (dump_file, "Not replacing ");
-			      print_gimple_expr (dump_file, stmt, 0, 0);
-			      fprintf (dump_file, " with ");
-			      print_generic_expr (dump_file, sprime, 0);
-			      fprintf (dump_file, " which would add a loop"
-				       " carried dependence to loop %d\n",
-				       b->loop_father->num);
-			    }
-			  continue;
+			  fprintf (dump_file, "Not replacing ");
+			  print_gimple_expr (dump_file, stmt, 0, 0);
+			  fprintf (dump_file, " with ");
+			  print_generic_expr (dump_file, sprime, 0);
+			  fprintf (dump_file, " which would add a loop"
+				   " carried dependence to loop %d\n",
+				   b->loop_father->num);
 			}
+		      /* Don't keep sprime available.  */
+		      eliminate_push_avail (lhs);
+		      sprime = NULL_TREE;
 		    }
 		}
+	    }
+
+	  if (sprime)
+	    {
+	      /* If we can propagate the value computed for LHS into
+		 all uses don't bother doing anything with this stmt.  */
+	      if (may_propagate_copy (lhs, sprime))
+		{
+		  /* Mark it for removal.  */
+		  el_to_remove.safe_push (stmt);
+
+		  /* ???  Don't count copy/constant propagations.  */
+		  if (gimple_assign_single_p (stmt)
+		      && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
+			  || gimple_assign_rhs1 (stmt) == sprime))
+		    continue;
+
+		  if (dump_file && (dump_flags & TDF_DETAILS))
+		    {
+		      fprintf (dump_file, "Replaced ");
+		      print_gimple_expr (dump_file, stmt, 0, 0);
+		      fprintf (dump_file, " with ");
+		      print_generic_expr (dump_file, sprime, 0);
+		      fprintf (dump_file, " in all uses of ");
+		      print_gimple_stmt (dump_file, stmt, 0, 0);
+		    }
+
+		  pre_stats.eliminations++;
+		  continue;
+		}
+
+	      /* If this is an assignment from our leader (which
+	         happens in the case the value-number is a constant)
+		 then there is nothing to do.  */
+	      if (gimple_assign_single_p (stmt)
+		  && sprime == gimple_assign_rhs1 (stmt))
+		continue;
+
+	      /* Else replace its RHS.  */
+	      bool can_make_abnormal_goto
+		  = is_gimple_call (stmt)
+		  && stmt_can_make_abnormal_goto (stmt);
 
 	      if (dump_file && (dump_flags & TDF_DETAILS))
 		{
@@ -4254,16 +4248,12 @@ eliminate_dom_walker::before_dom_children (basic_block b)
 	      if (TREE_CODE (sprime) == SSA_NAME)
 		gimple_set_plf (SSA_NAME_DEF_STMT (sprime),
 				NECESSARY, true);
-	      /* We need to make sure the new and old types actually match,
-		 which may require adding a simple cast, which fold_convert
-		 will do for us.  */
-	      if ((!rhs || TREE_CODE (rhs) != SSA_NAME)
-		  && !useless_type_conversion_p (gimple_expr_type (stmt),
-						 TREE_TYPE (sprime)))
-		sprime = fold_convert (gimple_expr_type (stmt), sprime);
 
 	      pre_stats.eliminations++;
-
+	      gimple orig_stmt = stmt;
+	      if (!useless_type_conversion_p (TREE_TYPE (lhs),
+					      TREE_TYPE (sprime)))
+		sprime = fold_convert (TREE_TYPE (lhs), sprime);
 	      tree vdef = gimple_vdef (stmt);
 	      tree vuse = gimple_vuse (stmt);
 	      propagate_tree_value_into_stmt (&gsi, sprime);
@@ -4291,135 +4281,183 @@ eliminate_dom_walker::before_dom_children (basic_block b)
 		  if (dump_file && (dump_flags & TDF_DETAILS))
 		    fprintf (dump_file, "  Removed AB side-effects.\n");
 		}
+
+	      continue;
 	    }
 	}
+
       /* If the statement is a scalar store, see if the expression
-	 has the same value number as its rhs.  If so, the store is
-	 dead.  */
-      else if (gimple_assign_single_p (stmt)
-	       && !gimple_has_volatile_ops (stmt)
-	       && !is_gimple_reg (gimple_assign_lhs (stmt))
-	       && (TREE_CODE (rhs) == SSA_NAME
-		   || is_gimple_min_invariant (rhs)))
-	{
-	  tree val;
-	  val = vn_reference_lookup (gimple_assign_lhs (stmt),
-				     gimple_vuse (stmt), VN_WALK, NULL);
-	  if (TREE_CODE (rhs) == SSA_NAME)
-	    rhs = VN_INFO (rhs)->valnum;
-	  if (val
-	      && operand_equal_p (val, rhs, 0))
-	    {
-	      if (dump_file && (dump_flags & TDF_DETAILS))
-		{
-		  fprintf (dump_file, "Deleted redundant store ");
-		  print_gimple_stmt (dump_file, stmt, 0, 0);
-		}
+         has the same value number as its rhs.  If so, the store is
+         dead.  */
+      if (gimple_assign_single_p (stmt)
+	  && !gimple_has_volatile_ops (stmt)
+	  && !is_gimple_reg (gimple_assign_lhs (stmt))
+	  && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
+	      || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
+        {
+          tree val;
+	  tree rhs = gimple_assign_rhs1 (stmt);
+          val = vn_reference_lookup (gimple_assign_lhs (stmt),
+                                     gimple_vuse (stmt), VN_WALK, NULL);
+          if (TREE_CODE (rhs) == SSA_NAME)
+            rhs = VN_INFO (rhs)->valnum;
+          if (val
+              && operand_equal_p (val, rhs, 0))
+            {
+              if (dump_file && (dump_flags & TDF_DETAILS))
+                {
+                  fprintf (dump_file, "Deleted redundant store ");
+                  print_gimple_stmt (dump_file, stmt, 0, 0);
+                }
+
+              /* Queue stmt for removal.  */
+              el_to_remove.safe_push (stmt);
+	      continue;
+            }
+        }
 
-	      /* Queue stmt for removal.  */
-	      el_to_remove.safe_push (stmt);
-	    }
-	}
-      /* Visit COND_EXPRs and fold the comparison with the
-	 available value-numbers.  */
-      else if (gimple_code (stmt) == GIMPLE_COND)
+      bool can_make_abnormal_goto = stmt_can_make_abnormal_goto (stmt);
+      bool was_noreturn = (is_gimple_call (stmt)
+			   && gimple_call_noreturn_p (stmt));
+      tree vdef = gimple_vdef (stmt);
+      tree vuse = gimple_vuse (stmt);
+
+      /* If we didn't replace the whole stmt (or propagate the result
+         into all uses), replace all uses on this stmt with their
+	 leaders.  */
+      use_operand_p use_p;
+      ssa_op_iter iter;
+      FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
 	{
-	  tree op0 = gimple_cond_lhs (stmt);
-	  tree op1 = gimple_cond_rhs (stmt);
-	  tree result;
-
-	  if (TREE_CODE (op0) == SSA_NAME)
-	    op0 = VN_INFO (op0)->valnum;
-	  if (TREE_CODE (op1) == SSA_NAME)
-	    op1 = VN_INFO (op1)->valnum;
-	  result = fold_binary (gimple_cond_code (stmt), boolean_type_node,
-				op0, op1);
-	  if (result && TREE_CODE (result) == INTEGER_CST)
+	  tree use = USE_FROM_PTR (use_p);
+	  /* ???  The call code above leaves stmt operands un-updated.  */
+	  if (TREE_CODE (use) != SSA_NAME)
+	    continue;
+	  tree sprime = eliminate_avail (use);
+	  if (sprime && sprime != use
+	      && may_propagate_copy (use, sprime)
+	      /* We substitute into debug stmts to avoid excessive
+	         debug temporaries created by removed stmts, but we need
+		 to avoid doing so for inserted sprimes as we never want
+		 to create debug temporaries for them.  */
+	      && (!inserted_exprs
+		  || TREE_CODE (sprime) != SSA_NAME
+		  || !is_gimple_debug (stmt)
+		  || !bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (sprime))))
 	    {
-	      if (integer_zerop (result))
-		gimple_cond_make_false (stmt);
-	      else
-		gimple_cond_make_true (stmt);
-	      update_stmt (stmt);
-	      el_todo = TODO_cleanup_cfg;
+	      propagate_value (use_p, sprime);
+	      gimple_set_modified (stmt, true);
+	      if (TREE_CODE (sprime) == SSA_NAME
+		  && !is_gimple_debug (stmt))
+		gimple_set_plf (SSA_NAME_DEF_STMT (sprime),
+				NECESSARY, true);
 	    }
 	}
+
       /* Visit indirect calls and turn them into direct calls if
-	 possible.  */
+	 possible using the devirtualization machinery.  */
       if (is_gimple_call (stmt))
 	{
-	  tree orig_fn = gimple_call_fn (stmt);
-	  tree fn;
-	  if (!orig_fn)
-	    continue;
-	  if (TREE_CODE (orig_fn) == SSA_NAME)
-	    fn = VN_INFO (orig_fn)->valnum;
-	  else if (TREE_CODE (orig_fn) == OBJ_TYPE_REF
-		   && TREE_CODE (OBJ_TYPE_REF_EXPR (orig_fn)) == SSA_NAME)
+	  tree fn = gimple_call_fn (stmt);
+	  if (fn
+	      && TREE_CODE (fn) == OBJ_TYPE_REF
+	      && TREE_CODE (OBJ_TYPE_REF_EXPR (fn)) == SSA_NAME)
 	    {
-	      fn = VN_INFO (OBJ_TYPE_REF_EXPR (orig_fn))->valnum;
-	      if (!gimple_call_addr_fndecl (fn))
+	      fn = ipa_intraprocedural_devirtualization (stmt);
+	      if (fn && dbg_cnt (devirt))
 		{
-		  fn = ipa_intraprocedural_devirtualization (stmt);
-		  if (fn)
-		    fn = build_fold_addr_expr (fn);
+		  if (dump_enabled_p ())
+		    {
+		      location_t loc = gimple_location (stmt);
+		      dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, loc,
+				       "converting indirect call to "
+				       "function %s\n",
+				       cgraph_get_node (fn)->name ());
+		    }
+		  gimple_call_set_fndecl (stmt, fn);
+		  gimple_set_modified (stmt, true);
 		}
 	    }
-	  else
-	    continue;
-	  if (gimple_call_addr_fndecl (fn) != NULL_TREE
-	      && useless_type_conversion_p (TREE_TYPE (orig_fn),
-					    TREE_TYPE (fn))
-              && dbg_cnt (devirt))
-	    {
-	      bool can_make_abnormal_goto
-		  = stmt_can_make_abnormal_goto (stmt);
-	      bool was_noreturn = gimple_call_noreturn_p (stmt);
-
-	      if (dump_enabled_p ())
-		{
-                  location_t loc = gimple_location (stmt);
-                  dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, loc,
-                                   "converting indirect call to function %s\n",
-                                   cgraph_get_node (gimple_call_addr_fndecl (fn))->name ());
-		}
-
-	      gimple_call_set_fn (stmt, fn);
-	      tree vdef = gimple_vdef (stmt);
-	      tree vuse = gimple_vuse (stmt);
-	      update_stmt (stmt);
-	      if (vdef != gimple_vdef (stmt))
-		VN_INFO (vdef)->valnum = vuse;
+	}
 
+      if (gimple_modified_p (stmt))
+	{
+	  /* If a formerly non-invariant ADDR_EXPR is turned into an
+	     invariant one it was on a separate stmt.  */
+	  if (gimple_assign_single_p (stmt)
+	      && TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
+	    recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
+	  gimple old_stmt = stmt;
+	  if (is_gimple_call (stmt))
+	    {
+	      /* ???  Only fold calls inplace for now, this may create new
+		 SSA names which in turn will confuse free_scc_vn SSA name
+		 release code.  */
+	      fold_stmt_inplace (&gsi);
 	      /* When changing a call into a noreturn call, cfg cleanup
 		 is needed to fix up the noreturn call.  */
 	      if (!was_noreturn && gimple_call_noreturn_p (stmt))
 		el_todo |= TODO_cleanup_cfg;
+	    }
+	  else
+	    {
+	      fold_stmt (&gsi);
+	      stmt = gsi_stmt (gsi);
+	      if ((gimple_code (stmt) == GIMPLE_COND
+		   && (gimple_cond_true_p (stmt)
+		       || gimple_cond_false_p (stmt)))
+		  || (gimple_code (stmt) == GIMPLE_SWITCH
+		      && TREE_CODE (gimple_switch_index (stmt)) == INTEGER_CST))
+		el_todo |= TODO_cleanup_cfg;
+	    }
+	  /* If we removed EH side-effects from the statement, clean
+	     its EH information.  */
+	  if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
+	    {
+	      bitmap_set_bit (need_eh_cleanup,
+			      gimple_bb (stmt)->index);
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		fprintf (dump_file, "  Removed EH side-effects.\n");
+	    }
+	  /* Likewise for AB side-effects.  */
+	  if (can_make_abnormal_goto
+	      && !stmt_can_make_abnormal_goto (stmt))
+	    {
+	      bitmap_set_bit (need_ab_cleanup,
+			      gimple_bb (stmt)->index);
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		fprintf (dump_file, "  Removed AB side-effects.\n");
+	    }
+	  update_stmt (stmt);
+	  if (vdef != gimple_vdef (stmt))
+	    VN_INFO (vdef)->valnum = vuse;
+	}
 
-	      /* If we removed EH side-effects from the statement, clean
-		 its EH information.  */
-	      if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
-		{
-		  bitmap_set_bit (need_eh_cleanup,
-				  gimple_bb (stmt)->index);
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    fprintf (dump_file, "  Removed EH side-effects.\n");
-		}
-
-	      /* Likewise for AB side-effects.  */
-	      if (can_make_abnormal_goto
-		  && !stmt_can_make_abnormal_goto (stmt))
-		{
-		  bitmap_set_bit (need_ab_cleanup,
-				  gimple_bb (stmt)->index);
-		  if (dump_file && (dump_flags & TDF_DETAILS))
-		    fprintf (dump_file, "  Removed AB side-effects.\n");
-		}
+      /* Make the new value available - for fully redundant LHS we
+         continue with the next stmt above.  */
+      if (lhs && TREE_CODE (lhs) == SSA_NAME)
+	eliminate_push_avail (lhs);
+    }
 
-	      /* Changing an indirect call to a direct call may
-		 have exposed different semantics.  This may
-		 require an SSA update.  */
-	      el_todo |= TODO_update_ssa_only_virtuals;
+  /* Replace destination PHI arguments.  */
+  edge_iterator ei;
+  edge e;
+  FOR_EACH_EDGE (e, ei, b->succs)
+    {
+      for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gimple phi = gsi_stmt (gsi);
+	  use_operand_p use_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
+	  tree arg = USE_FROM_PTR (use_p);
+	  if (TREE_CODE (arg) != SSA_NAME
+	      || virtual_operand_p (arg))
+	    continue;
+	  tree sprime = eliminate_avail (arg);
+	  if (sprime && may_propagate_copy (arg, sprime))
+	    {
+	      propagate_value (use_p, sprime);
+	      if (TREE_CODE (sprime) == SSA_NAME)
+		gimple_set_plf (SSA_NAME_DEF_STMT (sprime), NECESSARY, true);
 	    }
 	}
     }
@@ -4442,7 +4480,6 @@ eliminate (bool do_pre)
 {
   gimple_stmt_iterator gsi;
   gimple stmt;
-  unsigned i;
 
   need_eh_cleanup = BITMAP_ALLOC (NULL);
   need_ab_cleanup = BITMAP_ALLOC (NULL);
@@ -4460,41 +4497,37 @@ eliminate (bool do_pre)
 
   /* We cannot remove stmts during BB walk, especially not release SSA
      names there as this confuses the VN machinery.  The stmts ending
-     up in el_to_remove are either stores or simple copies.  */
-  FOR_EACH_VEC_ELT (el_to_remove, i, stmt)
+     up in el_to_remove are either stores or simple copies.
+     Remove stmts in reverse order to make debug stmt creation possible.  */
+  while (!el_to_remove.is_empty ())
     {
-      tree lhs = gimple_assign_lhs (stmt);
-      tree rhs = gimple_assign_rhs1 (stmt);
-      use_operand_p use_p;
-      gimple use_stmt;
-
-      /* If there is a single use only, propagate the equivalency
-	 instead of keeping the copy.  */
-      if (TREE_CODE (lhs) == SSA_NAME
-	  && TREE_CODE (rhs) == SSA_NAME
-	  && single_imm_use (lhs, &use_p, &use_stmt)
-	  && may_propagate_copy (USE_FROM_PTR (use_p), rhs))
+      stmt = el_to_remove.pop ();
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
 	{
-	  SET_USE (use_p, rhs);
-	  update_stmt (use_stmt);
-	  if (inserted_exprs
-	      && bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (lhs))
-	      && TREE_CODE (rhs) == SSA_NAME)
-	    gimple_set_plf (SSA_NAME_DEF_STMT (rhs), NECESSARY, true);
+	  fprintf (dump_file, "Removing dead stmt ");
+	  print_gimple_stmt (dump_file, stmt, 0, 0);
 	}
 
-      /* If this is a store or a now unused copy, remove it.  */
-      if (TREE_CODE (lhs) != SSA_NAME
-	  || has_zero_uses (lhs))
+      tree lhs;
+      if (gimple_code (stmt) == GIMPLE_PHI)
+	lhs = gimple_phi_result (stmt);
+      else
+	lhs = gimple_get_lhs (stmt);
+
+      if (inserted_exprs
+	  && TREE_CODE (lhs) == SSA_NAME)
+	bitmap_clear_bit (inserted_exprs, SSA_NAME_VERSION (lhs));
+
+      gsi = gsi_for_stmt (stmt);
+      if (gimple_code (stmt) == GIMPLE_PHI)
+	remove_phi_node (&gsi, true);
+      else
 	{
 	  basic_block bb = gimple_bb (stmt);
-	  gsi = gsi_for_stmt (stmt);
 	  unlink_stmt_vdef (stmt);
 	  if (gsi_remove (&gsi, true))
 	    bitmap_set_bit (need_eh_cleanup, bb->index);
-	  if (inserted_exprs
-	      && TREE_CODE (lhs) == SSA_NAME)
-	    bitmap_clear_bit (inserted_exprs, SSA_NAME_VERSION (lhs));
 	  release_defs (stmt);
 	}
     }

gcc/tree-ssa-propagate.c

@@ -1410,11 +1410,6 @@ replace_exp (use_operand_p op_p, tree val)
 void
 propagate_tree_value (tree *op_p, tree val)
 {
-  gcc_checking_assert (!(TREE_CODE (val) == SSA_NAME
-			 && *op_p
-			 && TREE_CODE (*op_p) == SSA_NAME
-			 && !may_propagate_copy (*op_p, val)));
-
   if (TREE_CODE (val) == SSA_NAME)
     *op_p = val;
   else