> >
> >> (insn 20 19 23 2 (set (reg/v:DI 200 [ val+-4 ])
> >> (sign_extend:DI (subreg:SI (reg/v:DI 200 [ val+-4 ]) 4)))
> >> "/app/example.cpp":7:29 -1
> >> (nil))
>
> Haven't had chance to compile and look at it properly, but this subreg
> seems suspicious for MIPS, given the definition of TRULY_NOOP_TRUNCATION.
> We should instead use a truncdisi2 to narrow reg:DI 200 to an SI register,
> and then sign_extend it.
>
> This is easily missed in target-independent code because so few targets
> define TRULY_NOOP_TRUNCATION.
>
> Where is the subreg being generated?
>
It's from expand_assignment(tree to, tree from, bool nontemporal) in expr.cc.
to_rtx = expand_expr (tem, NULL_RTX, VOIDmode, EXPAND_WRITE);
--
YunQiang Su
