erichkeane added a subscriber: mgehre-amd. erichkeane added a comment. In D117238#3338071 <https://reviews.llvm.org/D117238#3338071>, @mariospr wrote:
> In D117238#3270125 <https://reviews.llvm.org/D117238#3270125>, @aaron.ballman > wrote: > >> Updated to allow targets to specify the max bitwidth. I was aware that the >> x86 backend had issues with doing division on larger `_BitInt` objects, but >> it turns out *all* backends fail to support `_BitInt(129)` or wider >> division. Because division is a pretty common operation on numeric data >> types, it seemed to be more user-friendly to specify that we only support >> 128 bits or less. I tried to make it exceptionally clear that I consider >> this to be a backend bug though -- we will support wider bit widths in the >> future once backends have been fixed. These changes make that future path >> easier to opt into. > > Hi! I know this question might be very hard to answer but even so I hope you > don't mind me trying 😇 ... do you know whether there is any estimation of > when `_BitInt(N) / N > 128` will be supported once again in Clang? I'm not an > expert at all on this topic (just registered here to comment! 🙂 ) but this > hit us in a Chromium-based project which relied on `_BITINT(256)` now that > Chromium 100 updated to Clang 15. And while we're already looking into > alternative ways of dealing with is (e.g. maybe using Boost's > `multiprecision` module), it would be very interesting if we could get a > sense (if it's even possible) on how long we could expect the current > situation to last. > > Again, I understand there might not be a clear answer for this at the moment > but, since I'm no expert on the matter and I couldn't figure out myself the > exact situation by reading this and other tickets in the tracker I thought, I > thought I'd ask just in case. > > Thanks in advance regardless of the answer! > Mario Hi Mario! Thank you for inquiring! As you may know, we disabled _BitInt this large since we couldn't handle division/modulus in the code generators. There is an RFC currently underway (as of today, we have the patches to start supporting this in the backend!) here: https://discourse.llvm.org/t/rfc-add-support-for-division-of-large-bitint-builtins-selectiondag-globalisel-clang/60329 I'm hopeful that the answer here is 'in the near future'. @mgehre-amd should be able to at least partially revert this patch once the library changes/llvm code generator changes make it in. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D117238/new/ https://reviews.llvm.org/D117238 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
