Index: testsuite/gcc.dg/torture/pr81245.c
===================================================================
--- testsuite/gcc.dg/torture/pr81245.c	(nonexistent)
+++ testsuite/gcc.dg/torture/pr81245.c	(working copy)
@@ -0,0 +1,16 @@
+/* { dg-options "-ffast-math" } */
+/* { dg-do compile } */
+/* This test used to crash the vectorizer as the ifconvert pass
+   used to convert the if to copysign but called update_stmt on
+   the old statement after calling fold_stmt. */
+double sg[18];
+void f(void)
+{
+  for (int i = 0 ;i < 18;i++)
+  {
+    if (sg[i] < 0.0)
+      sg[i] = -1.0;
+    else
+      sg[i] = 1.0;
+  }
+}
Index: tree-if-conv.c
===================================================================
--- tree-if-conv.c	(revision 249844)
+++ tree-if-conv.c	(working copy)
@@ -1853,8 +1853,11 @@
       new_stmt = gimple_build_assign (res, rhs);
       gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
       gimple_stmt_iterator new_gsi = gsi_for_stmt (new_stmt);
-      fold_stmt (&new_gsi, ifcvt_follow_ssa_use_edges);
-      update_stmt (new_stmt);
+      if (fold_stmt (&new_gsi, ifcvt_follow_ssa_use_edges))
+	{
+	  new_stmt = gsi_stmt (new_gsi);
+	  update_stmt (new_stmt);
+	}
 
       if (dump_file && (dump_flags & TDF_DETAILS))
 	{