fhahn added a comment. In D64128#1572504 <https://reviews.llvm.org/D64128#1572504>, @rjmccall wrote:
> I would be opposed to any addition of a `-f` flag for this absent any > evidence that it's valuable for some actual C code; this patch appears to be > purely speculative. I certainly don't think we should be adding it > default-on. Your argument about alignment is what I was referring to when I > mentioned that this is enforcing alignment restrictions in places we > traditionally and intentionally haven't. > > Note that it won't help Clang's major uses of `PointerIntPair` and > `PointerUnion` because our traits say that types like `Decl` and `Type` have > more alignment bits than their formal alignment would indicate, and > `PointerIntPair` occupies alignment bits starting with the most significant. In total with this patch, we generate ~180 ptrmask calls when building llvm/clang. As mentioned above, we miss out a bunch of cases, because of `PointerIntPair` putting its data into the most significant bits. I guess we could cover those cases with a builtin and the main motivation for this patch mostly goes away. Do we have any policies against using clang-only builtins in the codebase? Anyways, thanks for all the feedback and discussion, it was really helpful! Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D64128/new/ https://reviews.llvm.org/D64128 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
