[PATCH] D71373: [ConstantFolding] Disable constant folding for bitcasts to x86_fp80

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

Is this really the only place where we fold fp80 bitcasts?  I guess it might be.

Would it make sense to allow encoding these non-canonical values into an APFloat?  (Still treating it as a NaN, but keeping around enough information to reconstitute it if bitcastToAPInt is called.)  If we don't think that's worthwhile, this seems like the right approach.

> We could maybe be smarter and look at the value we're going to convert and make sure its safe

I'm a little concerned this might show up in more cases than you expect, where we end up with a bitcast in code that isn't explicitly reintepreting floats.  For example, in code using C unions.


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  https://reviews.llvm.org/D71373/new/

https://reviews.llvm.org/D71373