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Re: RFC: GIMPLE tuples. Design and implementation proposal
Ian Lance Taylor wrote on 04/10/07 13:53:
> I seem to recall that at one point somebody worked on a gensimplify
> program or something like that. Would it make sense to revive that
> approach, and use it to generate simplifiers for trees, GIMPLE, and
> RTL, to avoid triplification of these basic optimizations?
Perhaps. This would allow us to define folding/simplification using a
pattern matching system. I think I like this better than the other two
choices.
Replicating fold-const.c for GIMPLE would involve a bit of code
duplication, but since GIMPLE is a strict subset of ASTs, I think it
would be a fraction of what we have today. Still, it's annoying and we
should probably avoid it.
> Or should we instead rewrite fold-const.c to work on GIMPLE rather
> than trees, thus essentially removing constant folding from the
> front-ends? If we follow that path somebody would need to think about
> the effect on warnings issued by the front-end, and on
> __builtin_constant_p.
I don't think we want to do that. Folding and simplification needs to
be done at just about every level.