In <https://gcc.gnu.org/ml/gcc-patches/2019-05/msg01417.html>:
...a change introduced in r94104 where BITS_PER_WORD was chosenperhaps because we expect register-sized writes into this area.

See <https://gcc.gnu.org/ml/gcc-patches/2005-01/msg01564.html>
for the r94104 change.

	* function.c (assign_parm_setup_block): Raise alignment of
	stacked parameter only for STRICT_ALIGNMENT targets.

From-SVN: r271497