------- Comment #10 from rguenther at suse dot de 2010-09-04 14:11 ------- Subject: Re: VRP misses oppurtunity for statement folding.
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 > ------- > Hi, > 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 route. > 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. Yes ;) > 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). Richard. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45522
