[codegen] equivalent bit manipulation code produces different assembly

On godbolt: https://godbolt.org/z/ebj8rhqja

The following two options:

```c++
std::uint32_t option1(std::uint8_t vecHeader) {
vecHeader >>= 4;
if (vecHeader != 0xF) [[likely]] {
return vecHeader;
} else {
return foo();
}
}

std::uint32_t option2(std::uint8_t vecHeader) {
if ((vecHeader & 0xF0) != 0xF0) [[likely]] {
return vecHeader >> 4;
} else {
return foo();
}
}
```

should result in the same assembly but they don't

Start with the Godbolt reproducer at https://godbolt.org/z/ebj8rhqja and compare the assembly produced for option1 and option2. Trace the relevant compiler code-generation or optimization path for these C++ bit-manipulation forms. Done means equivalent options produce the same assembly without changing the observed behavior.

Written by the indexing model from the issue text.