This helpers are not for general CR calculation, they are just for the
common case of the sign extended result of integer instructions if the
rc bit is set.
They must not be used by other instructions like cmp, so there is no
need to be as flexible.
cmpi shall compare two signed 32 bit values. The used difference a-b
may overflow and so the resulting 32 bit value can't represent it.
A correct way would be cr = s64(a) - s64(b) and it should be done in
this way in the JITs, but the Interpreter shall implement the most
readable way.
Also drops the now unused helper function.
Core::PauseAndLock requires all calls to it to be balanced, like this:
const bool was_unpaused = Core::PauseAndLock(true);
// do stuff on the CPU thread
Core::PauseAndLock(false, was_unpaused);
Aside from being a bit cumbersome, it turns out all callers really
don't need to know about was_unpaused at all. They just need to do
something on the CPU thread safely, including locking/unlocking.
So this commit replaces Core::PauseAndLock with a function that
makes both the purpose and the scope of what is being run on the
CPU thread visually clear. This makes it harder to accidentally run
something on the wrong thread, or forget the second call to
PauseAndLock to unpause, or forget that it needs to be passed
was_unpaused at the end.
We also don't need comments to indicate code X is being run on the
CPU thread anymore, as the function name makes it obvious.
struct GekkoOPTemplate was implemented differently in different
compilation units, which breaks the ODR and could end up causing issues
as symbols exported from one compilation unit could end up being used by
another even if they have different implementations.
This puts them in an anonymous namespace, restricting any generated
symbols to the single compilation unit.
The efficient function (that is nearly the same as
https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2)
replaces one loop based instance (which also reused the xx variable
afterwards, whereas it should have used htabmask instead) and one
instance using the population count a.k.a. Hamming weigth.
The accuracy doesn't match ppc, and worse, it doesn't set the error flags if the input is zero.
Lets stop to ship broken instructions, so right now, the interpreter is the closest one.
