[PATCH] D65280: Add a pass to lower is.constant and objectsize intrinsics

[Joerg Sonnenberger via Phabricator via llvm-commits]

joerg added a comment.

Looking a bit more into the details. Chandler, you've originally suggested going with the LowerAtomic route and that actually does create code that fails the SDAG lowering if the pass is skipped, e.g. on ARM.
The second part is currently overlapping with the CodeGenPrepare pass. I can cleanup the implementation somewhat by reusing the same functionality as that pass is using OR I could factor out a minimal branch for doing the constant folding optimization from CodeGenPrepare as a general branch that is included in the pass chain for `-O0`, e.g. instead of the more general CodeGenPrepare pass. The main difference is that the non-optimized build would not get any recursive folding from PHI-simplification, but I think that's fine for the original use case. It would also not get the block merging, but again, that seems to be fine for the constraints.


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  https://reviews.llvm.org/D65280/new/

https://reviews.llvm.org/D65280