nikic wrote: > > It occurs to me that the current return attribute propagation is currently > > buggy for poison-generating attributes: https://llvm.godbolt.org/z/x8n18q9Mj > > In this case the argument to use() will now be poison as well, while before > > inlining only the return value was poison. > > This code needs to distinguish poison and UB generating attributes. > > Good catch. I think this means basically `nonnull`, `noundef`, and `align` > can only be propagated if there are no other uses in to-be-inlined function. > That sound right or do you see any more robust way forward?
Limiting poison-generating attributes to one-use while keeping the rest of the logic (with guarantee-to-transfer) would be the simplest way to make the existing code correct. There are two additional ways to generalize: * If the return is also noundef, we don't need one-use. * Just one-use is enough for poison-generating, we don't need guaranteed-to-transfer, BUT: we need to be careful about an implicit "use" in the call itself. That is, if the call we're transfering to is noundef and we only check one-use but not guaranteed-to-transfer, we would convert poison into UB at that point. https://github.com/llvm/llvm-project/pull/66036 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
