arsenm added a comment. In D128907#3652140 <https://reviews.llvm.org/D128907#3652140>, @jdoerfert wrote:
> In D128907#3652077 <https://reviews.llvm.org/D128907#3652077>, @arsenm wrote: > >> In D128907#3650750 <https://reviews.llvm.org/D128907#3650750>, @jdoerfert >> wrote: >> >>> That said, I doubt this is even what we want. Throwing away the benefits of >>> the noundef for one special case. IIRC, I mentioned alternatives in the >>> other discussion already,... not that I have a link handy. >> >> I've spent a while thinking about this and don't see a better option. It's >> one special case, but since that special case can be called from arbitrary >> user code, I don't see how we can preserve noundef. We can't specially treat >> the handful of special intrinsics/operands for this, since we would >> transitively need to apply this to any user code which calls those functions > > I guess, that is the actual question here: Does CUDA/HIP overwrite the > semantics of the base language entirely or make exceptions for the intrinsics > they added. > From what I can tell, CUDA/HIP did the latter. I am not sure how much their > standards (if any) mention this. As far as I can tell there's no explicit mention of this. However, there is apparently code in the wild where people are relying on this behavior. It seems almost reasonable, but I do wish this were defined. > OpenMP offloading, for example, does not overwrite the base language (C/C++). > For OpenMP we would want to make the intrinsics special but that's it. We > would even be fine without any special handling as the only uses are in our > runtime (or other clang shipped code). > > If the HIP/CUDA people think we should give up on noundef arguments > completely, let's do it by language rather than some implicit property > (convergent). OpenCL & SYCL people should also comment. (ping @tra, > @RaviNarayanaswamy, @bader, @Anastasia) I do think we could go backwards and infer noundef like any other attribute, and take care to avoid inferring it in the presence of these intrinsics. I thought it was weird clang was adding these upfront in the first place. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D128907/new/ https://reviews.llvm.org/D128907 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
