[PATCH] D59065: [BasicAA] Simplify inttoptr(and(ptrtoint(X), C)) to X, if C preserves all significant bits.

[Sanjoy Das via Phabricator via llvm-commits]

sanjoy added a comment.

> Ah thanks, I was missing the global nature of physical pointers. I couldn't find this described anywhere (besides some of those things mentioned at a tutorial at EuroLLVM). If this is not described anywhere, do you think it would make sense to add it to the AliasAnalysis documentation page, for example?

Yes, I think we should add this to the AA docs.  I think the best reference for a consistent LLVM memory model is https://sf.snu.ac.kr/publications/llvmtwin.pdf .

> Also, is the bitwise equality propagation just function local or across the whole module? If it is function-local, we might be able to convert ` inttoptr(and(ptrtoint(X), C)) ` chains to the intrinsic early on, for functions that just contain the operations to strip away the bits, or somewhere else?

Generally I don't think we can define semantics like these as function local since it would make inlining and outlining non-behavior preserving.


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https://reviews.llvm.org/D59065