[llvm] Reland "[ValueTracking] Compute knownbits from known fp classes" (PR #92084)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

Reduced reproducer:

```
define i64 @test(double %x) {
  %cmp = fcmp uno double %x, 0.000000e+00
  br i1 %cmp, label %if.then1, label %if.else

if.then1:
  br i1 %cmp, label %if.else, label %if.then2

if.then2:
  %cast = bitcast double %x to i64
  %and = and i64 %cast, 1
  ret i64 %and

if.else:
  ret i64 0
}
```

https://github.com/llvm/llvm-project/pull/92084