vec.h (vec::safe_grow): Guard against a grow to zero size.

2014-12-15  Richard Biener  <rguenther@suse.de>

	* vec.h (vec::safe_grow): Guard against a grow to zero size.

From-SVN: r218749

gcc/ChangeLog

 2014-12-15  Richard Biener  <rguenther@suse.de>
 
+	* vec.h (vec::safe_grow): Guard against a grow to zero size.
+
+2014-12-15  Richard Biener  <rguenther@suse.de>
+
 	PR middle-end/64295
 	* match.pd (X / CST -> X * (1 / CST): Use const_binop instead of
 	fold_binary to compute the constant to multiply with.

gcc/vec.h

@@ -1574,7 +1574,10 @@ vec<T, va_heap, vl_ptr>::safe_grow (unsigned len MEM_STAT_DECL)
   unsigned oldlen = length ();
   gcc_checking_assert (oldlen <= len);
   reserve_exact (len - oldlen PASS_MEM_STAT);
-  m_vec->quick_grow (len);
+  if (m_vec)
+    m_vec->quick_grow (len);
+  else
+    gcc_checking_assert (len == 0);
 }