[llvm] ValueTracking: Identify implied fp classes by general fcmp (PR #66505)

[Jorge Gorbe Moya via llvm-commits]

slackito wrote:

FYI I'm seeing the same assertion being triggered after d55692d60d218f402ce107520daabed15f2d9ef6 in some Tensorflow tests.
```
assert.h assertion failed at [third_party/llvm/llvm-project/llvm/lib/Analysis/ValueTracking.cpp:4186](https://cs.corp.google.com/piper///depot/google3/third_party/llvm/llvm-project/llvm/lib/Analysis/ValueTracking.cpp?l=4186&ws=jgorbe/61988&snapshot=467) in std::tuple<Value *, FPClassTest, FPClassTest> llvm::fcmpImpliesClass(CmpInst::Predicate, const Function &, Value *, const APFloat *, bool): (RHSClass == fcPosNormal || RHSClass == fcNegNormal || RHSClass == fcPosSubnormal || RHSClass == fcNegSubnormal) && "should have been recognized as an exact class test"
```

I don't have a standalone repro yet.

https://github.com/llvm/llvm-project/pull/66505