diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8a38316..9247222 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2013-10-31  Cong Hou  <congh@google.com>
+
+	PR tree-optimization/58728
+	* tree-ssa-reassoc.c (suitable_cond_bb): Consider the situtation
+	that ==/!= comparisons between a variable and a constant may lead
+	to that the later phi arg of the variable is substitued by the
+	constant from prior passes, during range test optimization.
+
 2013-10-14  David Malcolm  <dmalcolm@redhat.com>
 
 	* dumpfile.h (gcc::dump_manager): New class, to hold state
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 075d071..44a5e70 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-10-31  Cong Hou  <congh@google.com>
+
+	PR tree-optimization/58728
+	* gcc.dg/tree-ssa/pr58728: New test.
+
 2013-10-14  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/58658
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr58728.c b/gcc/testsuite/gcc.dg/tree-ssa/pr58728.c
new file mode 100644
index 0000000..312aebc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr58728.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-reassoc1-details" } */
+
+int foo (unsigned int n)
+{
+  if (n != 0)
+    if (n != 1)
+      return ++n;
+  return n;
+}
+
+int bar (unsigned int n)
+{
+  if (n == 0)
+    ;
+  else if (n == 1)
+    ;
+  else
+    return ++n;
+  return n;
+}
+
+
+/* { dg-final { scan-tree-dump-times "Optimizing range tests" 2 "reassoc1" } } */
+/* { dg-final { cleanup-tree-dump "reassoc1" } } */
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index 6859518..bccf99f 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -2426,11 +2426,70 @@ suitable_cond_bb (basic_block bb, basic_block test_bb, basic_block *other_bb,
   for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
     {
       gimple phi = gsi_stmt (gsi);
+      tree phi_arg = gimple_phi_arg_def (phi, e->dest_idx);
+      tree phi_arg2 = gimple_phi_arg_def (phi, e2->dest_idx);
+
       /* If both BB and TEST_BB end with GIMPLE_COND, all PHI arguments
 	 corresponding to BB and TEST_BB predecessor must be the same.  */
-      if (!operand_equal_p (gimple_phi_arg_def (phi, e->dest_idx),
-			    gimple_phi_arg_def (phi, e2->dest_idx), 0))
-	{
+      if (!operand_equal_p (phi_arg, phi_arg2, 0))
+      {
+	/* If the condition in BB or TEST_BB is an NE or EQ comparison like
+	   if (n != N) or if (n == N), it is possible that the corresponding
+	   def of n in the phi function is replaced by N.  We should still allow
+	   range test optimization in this case.  */
+
+	tree lhs = NULL, rhs = NULL,
+	     lhs2 = NULL, rhs2 = NULL;
+	bool is_eq_expr = is_cond && (gimple_cond_code (stmt) == NE_EXPR
+					|| gimple_cond_code (stmt) == EQ_EXPR)
+				  && TREE_CODE (phi_arg) == INTEGER_CST;
+
+	if (is_eq_expr)
+	  {
+	    lhs = gimple_cond_lhs (stmt);
+	    rhs = gimple_cond_rhs (stmt);
+
+	    if (operand_equal_p (lhs, phi_arg, 0))
+	      {
+		tree t = lhs;
+		lhs = rhs;
+		rhs = t;
+	      }
+	    if (operand_equal_p (rhs, phi_arg, 0)
+		&& operand_equal_p (lhs, phi_arg2, 0))
+	      continue;
+	  }
+
+	gimple stmt2 = last_stmt (test_bb);
+	bool is_eq_expr2 = gimple_code (stmt2) == GIMPLE_COND
+			     && (gimple_cond_code (stmt2) == NE_EXPR
+				 || gimple_cond_code (stmt2) == EQ_EXPR)
+			     && TREE_CODE (phi_arg2) == INTEGER_CST;
+
+	if (is_eq_expr2)
+	  {
+	    lhs2 = gimple_cond_lhs (stmt2);
+	    rhs2 = gimple_cond_rhs (stmt2);
+
+	    if (operand_equal_p (lhs2, phi_arg2, 0))
+	      {
+		tree t = lhs2;
+		lhs2 = rhs2;
+		rhs2 = t;
+	      }
+	    if (operand_equal_p (rhs2, phi_arg2, 0)
+		&& operand_equal_p (lhs2, phi_arg, 0))
+	      continue;
+	  }
+
+	if (is_eq_expr && is_eq_expr2)
+	  {
+	    if (operand_equal_p (rhs, phi_arg, 0)
+		&& operand_equal_p (rhs2, phi_arg2, 0)
+		&& operand_equal_p (lhs, lhs2, 0))
+	      continue;
+	  }
+
 	  /* Otherwise, if one of the blocks doesn't end with GIMPLE_COND,
 	     one of the PHIs should have the lhs of the last stmt in
 	     that block as PHI arg and that PHI should have 0 or 1
@@ -2438,21 +2497,16 @@ suitable_cond_bb (basic_block bb, basic_block test_bb, basic_block *other_bb,
 	     considered.  */
 	  if (!is_cond)
 	    {
-	      if (gimple_phi_arg_def (phi, e->dest_idx)
-		  == gimple_assign_lhs (stmt)
-		  && (integer_zerop (gimple_phi_arg_def (phi, e2->dest_idx))
-		      || integer_onep (gimple_phi_arg_def (phi,
-							   e2->dest_idx))))
+	      if (phi_arg == gimple_assign_lhs (stmt)
+		  && (integer_zerop (phi_arg2) || integer_onep (phi_arg2)))
 		continue;
 	    }
 	  else
 	    {
 	      gimple test_last = last_stmt (test_bb);
 	      if (gimple_code (test_last) != GIMPLE_COND
-		  && gimple_phi_arg_def (phi, e2->dest_idx)
-		     == gimple_assign_lhs (test_last)
-		  && (integer_zerop (gimple_phi_arg_def (phi, e->dest_idx))
-		      || integer_onep (gimple_phi_arg_def (phi, e->dest_idx))))
+		  && phi_arg2 == gimple_assign_lhs (test_last)
+		  && (integer_zerop (phi_arg) || integer_onep (phi_arg)))
 		continue;
 	    }