Как работает функция getHashCode() ?

INT32 ObjectNative::GetHashCodeEx(Object *objRef)
{
    CONTRACTL
    {
        MODE_COOPERATIVE;
        THROWS;
        GC_NOTRIGGER;
        SO_TOLERANT;
    }
    CONTRACTL_END
 
    VALIDATEOBJECTREF(objRef);
    // This loop exists because we're inspecting the header dword of the object
    // and it may change under us because of races with other threads.
    // On top of that, it may have the spin lock bit set, in which case we're
    // not supposed to change it.
    // In all of these case, we need to retry the operation.
    DWORD iter = 0;
    while (true)
    {
        DWORD bits = objRef->GetHeader()->GetBits();
 
        if (bits & BIT_SBLK_IS_HASH_OR_SYNCBLKINDEX)
        {
            if (bits & BIT_SBLK_IS_HASHCODE)
            {
                // Common case: the object already has a hash code
                return  bits & MASK_HASHCODE;
            }
            else
            {
                // We have a sync block index. This means if we already have a hash code,
                // it is in the sync block, otherwise we generate a new one and store it there
                SyncBlock *psb = objRef->GetSyncBlock();
                DWORD hashCode = psb->GetHashCode();
                if (hashCode != 0)
                    return  hashCode;
 
                hashCode = Object::ComputeHashCode();
 
                return psb->SetHashCode(hashCode);
            }
        }
        else
        {
            // If a thread is holding the thin lock or an appdomain index is set, we need a syncblock
            if ((bits & (SBLK_MASK_LOCK_THREADID | (SBLK_MASK_APPDOMAININDEX << SBLK_APPDOMAIN_SHIFT))) != 0)
            {
                objRef->GetSyncBlock();
                // No need to replicate the above code dealing with sync blocks
                // here - in the next iteration of the loop, we'll realize
                // we have a syncblock, and we'll do the right thing.
            }
            else
            {
                // We want to change the header in this case, so we have to check the BIT_SBLK_SPIN_LOCK bit first
                if (bits & BIT_SBLK_SPIN_LOCK)
                {
                    iter++;
                    if ((iter % 1024) != 0 && g_SystemInfo.dwNumberOfProcessors > 1)
                    {
                        YieldProcessor();           // indicate to the processor that we are spining
                    }
                    else
                    {
                        __SwitchToThread(0);
                    }
                    continue;
                }
 
                DWORD hashCode = Object::ComputeHashCode();
 
                DWORD newBits = bits | BIT_SBLK_IS_HASH_OR_SYNCBLKINDEX | BIT_SBLK_IS_HASHCODE | hashCode;
 
                if (objRef->GetHeader()->SetBits(newBits, bits) == bits)
                    return hashCode;
                // Header changed under us - let's restart this whole thing.
            }
        }
    }
}