efriedma added inline comments.
================ Comment at: clang/lib/CodeGen/CGBuiltin.cpp:8047 + Value *PFalse = Constant::getNullValue(PTrue->getType()); + Value *Sel = Builder.CreateSelect(CmpNE, PTrue, PFalse); + return EmitSVEPredicateCast(Sel, cast<llvm::ScalableVectorType>(Ty)); ---------------- sdesmalen wrote: > efriedma wrote: > > The select might not be the best approach. I mean, it's semantically > > correct, but the backend currently doesn't know how to lower a select like > > that. And even if it did, it's probably better to avoid generating it for > > now. > > > > Maybe this should use whilelo directly, since that's what the backend would > > eventually use anyway. > > but the backend currently doesn't know how to lower a select like that > Yes I noticed, that was the reason for D79356 (added as parent revision) > > > And even if it did, it's probably better to avoid generating it for now. > Is that because there are common optimisations on the select? I thought it > would be safe to use the 'full vector' form of `select` where the predicate > is a scalar (and both operands are splats) Yes, the idea would just be to avoid common optimizations. Maybe there aren't that many vector optimizations on a select with a scalar condition, though. If it isn't blowing up, I guess it's fine. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D79357/new/ https://reviews.llvm.org/D79357 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
