kpn added a comment. In D99675#2696327 <https://reviews.llvm.org/D99675#2696327>, @pengfei wrote:
> In D99675#2695424 <https://reviews.llvm.org/D99675#2695424>, @kpn wrote: > >> What changes are needed for a backend, and what happens if they aren't done? > > As far as I understand it, backend does optimizations based on patterns of > the known nodes and MIs. Inserting a new node/MI will block any optimizations > across the fence. So it respects the semantics of the intrinsic without > target special chenges. > I'm not sure if there's room for optimization cross the `arithmetic.fence`. > If there is and no changes for it, backend may have some performance loss > under these circumstances. > >> Having something needed for correctness silently not work seems ... >> sub-optimal. > > I think backend is conservative for optimizations when use the intrinsic. It > won't have correctness issue silently, but performance loss might. OK, that sounds fine, then. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D99675/new/ https://reviews.llvm.org/D99675 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
