diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4cf1e815ce4f..fe9a60a0c779 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-01-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/68269
+	* combine.c (expand_field_assignment): Punt if compute_mode is
+	unsupported scalar mode.
+
 2016-01-14  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/66856
diff --git a/gcc/combine.c b/gcc/combine.c
index d088031b853f..2f913dd8ea97 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -7247,6 +7247,10 @@ expand_field_assignment (const_rtx x)
       if (len >= HOST_BITS_PER_WIDE_INT)
 	break;
 
+      /* Don't try to compute in too wide unsupported modes.  */
+      if (!targetm.scalar_mode_supported_p (compute_mode))
+	break;
+
       /* Now compute the equivalent expression.  Make a copy of INNER
 	 for the SET_DEST in case it is a MEM into which we will substitute;
 	 we don't want shared RTL in that case.  */