Merge "If a general reduction kernel lacks a combiner function, synthesize one." am: 1ca1ee8
am: 77b7a39

* commit '77b7a394adf66687c11cc1e0ef6b093bb65ad460':
  If a general reduction kernel lacks a combiner function, synthesize one.

Change-Id: I7bfd692073b2d6b087788fce798bb6dd2bb1ddb0