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Re: [PATCH] Fix DCE REG_LIBCALL note moving from noop move insns (PR rtl-optimization/33644)
On 10/17/07, Eric Botcazou <ebotcazou@libertysurf.fr> wrote:
> > I think that when danny and i started this, it was not considered an
> > option to remove libcall notes. I never understood the reason for them,
>
> Libcalls notes make it possible for the optimizers to know that the libcall
> sequence has no side-effects, i.e. that is only used for its return value.
> See for example delete_trivially_dead_insns.
Which of course is information any sane backend would transmit without
adding special requirements all over the place for where you can place
insns, which insns you can move, and requiring walking *all the
instructions in the entire function to see if this is part of one of
the "special ones"*
>
> --
> Eric Botcazou
>