[llvm] [ConstantFolding] Respect AllowNonDeterministic when flushing denormals (PR #183031)

[Nikita Popov via llvm-commits]

nikic wrote:

> > Only dynamic is truly nondeterministic,
> 
> No, flushing is never guaranteed. Canonicalizes can be dropped. Input DAZ kind of has to be guaranteed, but not the output

I have a question about this: How is guaranteed input DAZ compatible with dropping canonicalize? If input flushing is guaranteed then `subnormal * 1.0` would still be required to return `0.0`, no? So it seems like input flushing also has to be nondet to match current optimization behavior (unless we want to say the optimization behavior is wrong).

https://github.com/llvm/llvm-project/pull/183031