There is the accidental addition of assert in GraphKit::load_array_element, which fails on ppc64le.
   http://hg.openjdk.java.net/aarch64-port/jdk8u-shenandoah/hotspot/annotate/4c12f2401645/src/share/vm/opto/graphKit.cpp#l1724

Also, the helper method g1_write_barrier_pre_helper should be inlined for clarity:
   http://hg.openjdk.java.net/aarch64-port/jdk8u-shenandoah/hotspot/annotate/4c12f2401645/src/share/vm/opto/graphKit.cpp#l3887