------- Comment #10 from rguenther at suse dot de 2010-09-04 14:11 -------
Subject: Re: VRP misses oppurtunity for statement
On Sat, 4 Sep 2010, hubicka at gcc dot gnu dot org wrote:
> ------- Comment #9 from hubicka at gcc dot gnu dot org 2010-09-04 13:51
> thanks. In meantime I made tree-ssa-pre to fold statements it produces and it
> gets me to bootstrapland with sanity check in expr.c except for Ada (with the
> patches I sent so far)
Well - that's a workaround and will cause us to miss PRE because we do
not fold during translation of expressions. So I wouldn't go down that
> So it seems that I need to basically duplicate all logic for initializer
> folding from tree-ssa-ccp.c into this function, right? I guess it makes sense,
> but it is all quite ugly.
> On VN side, i wondered if we can retire more of expand this way. For example
> dojump knows that:
> a = b ror x;
> if (a != 0)
> can be folded into:
> if (b != 0)
> (ror is rotation). I guess we should do this kind of tricks in VN instead?
Well ... it's not that easy (that's not CSE but tree-combining, so
the specific thing would fit to forwprop).