As preparation for updating the toolchain for building JDK 11 at Oracle, I'm fixing issues warnings introduced by the new toolchains. On Macosx, when using Xcode 9, there are a number of warnings triggered in Hotspot:

/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:176:31: warning: explicit instantiation of 'arraycopy_conjoint<signed char>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint<jbyte>(jbyte* src, jbyte* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:108:8: note: previous template specialization is here
  void arraycopy_conjoint<jbyte>(jbyte* src, jbyte* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:177:31: warning: explicit instantiation of 'arraycopy_conjoint<short>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint<jshort>(jshort* src, jshort* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:113:8: note: previous template specialization is here
  void arraycopy_conjoint<jshort>(jshort* src, jshort* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:178:31: warning: explicit instantiation of 'arraycopy_conjoint<int>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint<jint>(jint* src, jint* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:118:8: note: previous template specialization is here
  void arraycopy_conjoint<jint>(jint* src, jint* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:179:31: warning: explicit instantiation of 'arraycopy_conjoint<long>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint<jlong>(jlong* src, jlong* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:123:8: note: previous template specialization is here
  void arraycopy_conjoint<jlong>(jlong* src, jlong* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:181:31: warning: explicit instantiation of 'arraycopy_arrayof_conjoint<signed char>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_arrayof_conjoint<jbyte>(jbyte* src, jbyte* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:128:8: note: previous template specialization is here
  void arraycopy_arrayof_conjoint<jbyte>(jbyte* src, jbyte* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:182:31: warning: explicit instantiation of 'arraycopy_arrayof_conjoint<short>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_arrayof_conjoint<jshort>(jshort* src, jshort* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:135:8: note: previous template specialization is here
  void arraycopy_arrayof_conjoint<jshort>(jshort* src, jshort* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:183:31: warning: explicit instantiation of 'arraycopy_arrayof_conjoint<int>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_arrayof_conjoint<jint>(jint* src, jint* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:142:8: note: previous template specialization is here
  void arraycopy_arrayof_conjoint<jint>(jint* src, jint* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:184:31: warning: explicit instantiation of 'arraycopy_arrayof_conjoint<long>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_arrayof_conjoint<jlong>(jlong* src, jlong* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:149:8: note: previous template specialization is here
  void arraycopy_arrayof_conjoint<jlong>(jlong* src, jlong* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:186:31: warning: explicit instantiation of 'arraycopy_conjoint_atomic<signed char>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint_atomic<jbyte>(jbyte* src, jbyte* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:156:8: note: previous template specialization is here
  void arraycopy_conjoint_atomic<jbyte>(jbyte* src, jbyte* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:187:31: warning: explicit instantiation of 'arraycopy_conjoint_atomic<short>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint_atomic<jshort>(jshort* src, jshort* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:161:8: note: previous template specialization is here
  void arraycopy_conjoint_atomic<jshort>(jshort* src, jshort* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:188:31: warning: explicit instantiation of 'arraycopy_conjoint_atomic<int>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint_atomic<jint>(jint* src, jint* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:166:8: note: previous template specialization is here
  void arraycopy_conjoint_atomic<jint>(jint* src, jint* dst, size_t length) {
       ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:189:31: warning: explicit instantiation of 'arraycopy_conjoint_atomic<long>' that occurs after an explicit specialization has no effect [-Winstantiation-after-specialization]
template void AccessInternal::arraycopy_conjoint_atomic<jlong>(jlong* src, jlong* dst, size_t length);
                              ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/oops/accessBackend.cpp:171:8: note: previous template specialization is here
  void arraycopy_conjoint_atomic<jlong>(jlong* src, jlong* dst, size_t length) {
       ^
12 warnings generated.
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/logging/logConfiguration.cpp:303:16: warning: passing an object that undergoes default argument promotion to 'va_start' has undefined behavior [-Wvarargs]
  va_start(ap, exact_match);
               ^
/Users/ejoelsso/hg/jdk-newdevkit-hotspot/open/src/hotspot/share/logging/logConfiguration.cpp:299:66: note: parameter of type 'bool' is declared here
void LogConfiguration::configure_stdout(LogLevelType level, bool exact_match, ...) {
                                                                 ^
1 warning generated.