tree-if-conv.c (predicate_scalar_phi): Update new_stmt if fold_stmt returned true.

2017-06-30  Andrew Pinski  <apinski@cavium.com>

        * tree-if-conv.c (predicate_scalar_phi): Update new_stmt if
        fold_stmt returned true.
2017-06-30  Andrew Pinski  <apinski@cavium.com>

        * gcc.dg/torture/pr81245.c: New testcase.

From-SVN: r249854

gcc/ChangeLog

+2017-06-30  Andrew Pinski  <apinski@cavium.com>
+
+	* tree-if-conv.c (predicate_scalar_phi): Update new_stmt if
+	fold_stmt returned true.
+
 2017-06-30  Nathan Sidwell  <nathan@acm.org>
 
 	* ggc.h (empty_string): Delete.

gcc/testsuite/ChangeLog

+2017-06-30  Andrew Pinski  <apinski@cavium.com>
+
+	* gcc.dg/torture/pr81245.c: New testcase.
+
 2017-06-30  Aldy Hernandez  <aldyh@redhat.com>
 
 	* gcc.dg/Walloca-14.c: Adapt test to recognize new complaint of

gcc/testsuite/gcc.dg/torture/pr81245.c

+/* { 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;
+  }
+}

gcc/tree-if-conv.c

@@ -1853,8 +1853,11 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
       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))
 	{