> Hi!
>
> I faced the same issue but I had somewhat different RTL for the consumer:
>
> (insn 20 15 21 2 (set (reg/i:SI 0 r0)
> (minus:SI (subreg:SI (reg:DI 117) 4)
> (mult:SI (reg:SI 123)
> (reg:SI 114)))) gasman.c:4 48 {*mulsi3subsi})
>
> where (reg:DI 117) is produced by umulsidi3_v6 instruction. Is it
> really true that (subreg:SI (reg:DI 117) 4) may be forwarded in one
> cycle in this case?
If the accumulator can be forwarded (i.e. a SImode register), there isn't a
reason why a subreg:SI (reg:DI) will not get forwarded.
The subreg:SI is an artifact before register allocation, thus it's a
representation issue that the patch is fixing here unless I misunderstand your
question.
regards
Ramana
>
> Thanks,
> Nikolai
>
