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Re: [tree-ssa] Lazy updating of stmt operands
Hello,
> >> Which needs to pass through every single statement in the program. Not
> >> really terribly efficient.
> >>
> >*shrug*, it's used by SSA-CCP. Since def-use edges are only needed by
> >some passes, I don't think it would be worth our while trying to
> >maintain them in get_stmt_operands.
> >
> >But I'm ready to be convinced otherwise. Say, with an implementation
> >comparing both approaches with timings over a reasonable code base (a
> >typical GCC bootstrap or one of the compile-time related PRs).
> IMHO, when we have the need, then we'll expand on the immediate uses
> interface -- either by having a way to incrementally update it, or
> rebuild it.
>
> While it's nice to think about a world where you always have immediate uses,
> you end up with FUD chains if you do that -- with ultimately a tangled nest
> of pointers that is bloody impossible to work with in the real world.
why? I have this written and it does not seem very complicated. I
didn't get to measuring its speed yet, and of course there is unpleasant
memory overhead, but I don't see any other problems.
Zdenek