On some platfoms reading a 64-bit value is non-atomic and it is
possible that the two 32-bit values are read in the wrong order. To
ensure the tag is always read first this commit reads the tag before
reading the full 64-bit value.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
(cherry picked from commit 66a7dc4c72cb25df67e7f872bee7a20b5fa9c763)
df6dd69db8