[PATCH] D28193: NewGVN: Add UnknownExpression and create them for things we can't symbolize. Kill fragile machinery for handling null expressions.

[Davide Italiano via Phabricator via llvm-commits]

davide added a comment.

Also, after starring at the code for a bit, I think the  the idea of introducing an explicit `UnknownExpression` class instead of having specialized code logic for handling it is very nice. I think it also makes the code easier to read/understand. I did some profiling (on llvm itself, and on some internal benchmarks) and I haven't noticed this handling popping up so I think not using a `DenseSet` for now is the right thing)


https://reviews.llvm.org/D28193