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Re: [4.1] Fix PR rtl-optimization/29329
Eric Botcazou <ebotcazou@libertysurf.fr> writes:
>> I'm probably misunderstanding something here, but doesn't that mean you
>> end up with a REG_DEAD note for register 107 attached to an insn that
>> doesn't actually use register 107?
>
> No, distribute_notes scans the insn chain and punts.
Duh, right, sorry. I was definitely misunderstanding. I saw the
"tem = i3" in the patch and somehow got the impression you were
attaching the note to i3. That would have been "place = i3",
of course.
I still need a bit of hand-holding though. Why is this case any
different from a case in which I3 _did_ use the original rhs of I2,
the original rhs of I2 mentions ELIM_I2, but the simplified form of
I3 doesn't? The comments give an example of when this might happen.
Wouldn't we need to propagate the death note then too?
Richard