a non-standard construct. Instead, redefine struct _ia64_fpreg as a
union and put a long double in it. On ia64 and for LP64, this is
defined by the ABI to have 16-byte alignment. For ILP32 a long double
has 4-byte alignment, but we don't support ILP32.
Note that the in-memory image of a long double does not match the in-
memory image of spilled FP registers. This means that one cannot use
the fpr_flt field to interpet the bits. For this reason we continue
to use an aggregate type.
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