> That's always been my interpretation too. Seems like we may be changing
> the meaning of this macro...
The main (and essentially only) effect of WORD_REGISTER_OPERATIONS in the
compiler happens during combine and is explained by this comment taken from
eliminate_regs_1 and written by Jim in 1998:
/* On these machines, combine can create rtl of the form
(set (subreg:m1 (reg:m2 R) 0) ...)
where m1 < m2, and expects something interesting to
happen to the entire word. Moreover, it will use the
(reg:m2 R) later, expecting all bits to be preserved.
So if the number of words is the same, preserve the
subreg so that push_reloads can see it. */
&& ! ((x_size-1)/UNITS_PER_WORD == (new_size-1) UNITS_PER_WORD)