After upgrading to Xcode 7.3 (7D175), clang generates new warnings such as:

/Users/dsimon/hs-comp/hotspot/src/share/vm/oops/klass.hpp:327:58: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
    return (juint)lh >= (juint)(_lh_array_tag_type_value << _lh_array_tag_shift);
                                ~~~~~~~~~~~~~~~~~~~~~~~~ ^
/Users/dsimon/hs-comp/hotspot/src/share/vm/oops/klass.hpp:331:55: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
    return (jint)lh < (jint)(_lh_array_tag_type_value << _lh_array_tag_shift);
                             ~~~~~~~~~~~~~~~~~~~~~~~~ ^
/Users/dsimon/hs-comp/hotspot/src/share/vm/opto/library_call.cpp:3773:20: warning: shifting a negative signed value is undefined [-Wshift-negative-value]
                   << Klass::_lh_array_tag_shift)
                   ^

I think the fix is shown in http://hg.openjdk.java.net/graal/graal-jvmci-9/hotspot/rev/881f8ce4bb11

Also, the supported clang version check needs to be updated:

http://hg.openjdk.java.net/graal/graal-jvmci-9/hotspot/rev/a774e0a83dd4