[llvm] [KnownFPClass] Refine known classes for `KnownFPClass::bitcast` (PR #215708)

[via llvm-commits]

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+//===- KnownFPClassTest.cpp - KnownFPClass tests --------------------------===//
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ZERICO2005 wrote:

Ping @arsenm Would you be able to take a look at the updated test placement? I was also thinking of placing tests for the similar `KnownFPClass::toKnownBits` function in the same file.


https://github.com/llvm/llvm-project/pull/215708