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Re: impact of -minsert-sched-nops
David Edelsohn <dje@watson.ibm.com> writes:
> >>>>> Jack Howarth writes:
>
> Jack> Well, as I understood it, the -minsert-sched-nops feature could be
> Jack> enabled through either -mcpu=970 or -mcpu=G5 or -mcpu=power4 (which
> Jack> would make the code G5 specific) or just through -minsert-sched-nops
> Jack> which would limit the change to that optimization leaving the code
> Jack> G4 compatible. Or am I missing something here?
>
> -minsert-sched-nops *always* is compatible.
>
> The issue is what heuristic should GCC use to insert nops if it
> doesn't know it's targeting G5/POWER4? G4 doesn't have group dispatch
> restrictions.
-mtune=G5 should have the same effect as -mcpu=G5 for these purposes.
[I don't know if it does; but it's a bug if it doesn't.]
--
- Geoffrey Keating <geoffk@geoffk.org>