ASDenysPetrov added a comment. In D104285#2949772 <https://reviews.llvm.org/D104285#2949772>, @aaron.ballman wrote:
> I don't think that compilers will create a disjointed multidimensional array, > as that would waste space at runtime. However, I do think that *optimizers* > are getting much smarter about UB situations, saying "that can't happen", and > basing decisions on it. For example, this touches on pointer provenance which > is an open area of discussion in LLVM that's still being hammered out (it > also relates to the C `restrict` keyword). In a provenance world, the pointer > has more information than just its address; it also knows from where the > pointer was derived, so you can tell (in the backend) that `&ptr1[5]` and > `&ptr2[0]` point to *different* objects even if the pointer values are > identical. So while the runtime layout of the array object may *allow* for > these sort of type shenanigans with the most obvious implementation > strategies for multidimensional arrays, the programming language's object > model does not allow for them and optimizers may do unexpected things. This is really significant obstructions. As what I see the only thing left for us is to wait until the Standard transforms this //shenanigans// into legal operations and becomes closer to developers. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D104285/new/ https://reviews.llvm.org/D104285 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
