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Re: [MIPS] MADD issue
Paolo Bonzini <paolo.bonzini@lu.unisi.ch> writes:
>>> This should be a post-reload (i.e. predicated on reload_completed)
>>> split, I think.
>>
>> Actually, with the relatively recent lower-subreg work, it is
>> desirable to split this sort of instruction before reload. That is,
>> do an unconditional split.
>
> Right. Combine cannot cope with the resulting 4-insn sequence and merge
> it back with the multiplication, but split is ran after combine and
> before the second lower-subreg pass.
>
> So, making this an unconditional split should be the best of both worlds.
The problem is, combine is also one of the passes that was able to
optimise the split form so effectively. It's not the best of both
worlds from that point of view.
Richard