jfbastien wrote: > One observation on the example: it's a `fetch_add`, and with the fix I pushed > it converges (old 5, new 6) and writes the padding back canonical instead of > looping; GCC-14 appears to do the same. `compare_exchange` on that same > dirtied object does fail in both, since it's a single native `cmpxchg` over > the whole word. The object is out-of-contract either way, so happy to go with > whatever behavior you'd prefer to mandate here. > > For the well-formed test I'll switch to your > store-`b`-then-store-`a`-then-atomics shape.
Yes I think this is the right outcome. If it's a single-instruction cmpxchg that gets emitted, there ain't much we can do. @Bigcheese and @chandlerc might be able to provide more input, they both cared about this a lot when we were talking about padding bits in atomics. https://github.com/llvm/llvm-project/pull/204815 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
