This allows to safely implement archive contents caches.
The change to lilliput is needed to allow to keep move-constructot
semantics of ScriptStream which would otherwise disappear because
DisposablePtr is non-copyable
As much as this seems bad design, it's a real possibility in the original interpreters, furthermore
confirmed by the menu messages which are shown when the user tries to do that, so here we are...
The VM has been treating the entire area between the frame pointer and
the stack pointer as temp variables for the current function. There are
two problems with this:
1. The VM hasn't been updating the frame pointer correctly when multiple
methods are called within the same send/self/super instruction.
2. The VM has been recalculating the number of temp variables on every
instruction as the difference between the two pointers.
This is incorrect, as this changes with almost every instruction in
ways have nothing to do with the number of temp variables allocated
by the link instruction. Meanwhile, the VM has not been recording
the number of variables allocated by the link instruction.
The first discrepancy caused scripts to behave differently than in SSCI
when reading parameters out of bounds in certain situations.
It also prevented our uninitialized variable detection from detecting
certain reads. The second made the temp-count used for out of bounds
detection too large, made debugger output such as `stack` incorrect,
and made stepping through the link instruction in the debugger appear
to do nothing until stepping through the following instruction.
When multiple methods are called by a send/self/super instruction, each
method's link instruction increases the stack pointer further.
Method B's variables appear after method A's. The VM has been setting
the stack pointer correctly but it kept using the previous frame
pointer, so method B would re-use method A's stack area instead of the
area the VM had just allocated for B. If a script correctly initializes
variables before using them and doesn't use out of bounds parameters or
temp variables then this discrepancy doesn't make a difference.
But a lot of scripts do these bad things and accidentally rely on the
undefined values they read.
Now we update the frame pointer correctly when "carrying over" to
subsequent method calls from the same send/self/super instruction.
This matches SSCI behavior. We also now record the number of temp
variables that have been allocated by the link instruction and use
that instead of incorrectly recalculating on every instruction.
Fixes the KQ6 black widow lockup, and other KQ6 music bugs, where
scripts call Sound:fade without the required fourth parameter.
Sound:fade expects a fourth parameter, so reads it out of bounds,
and passes it as the stop-after-completion boolean to kDoSoundFade.
Scripts that called Sound:fade as the only method in a send got the same
results as in SSCI, but scripts that called Sound:play first didn't.
Fixes bugs #5625#5653#6120#6210#6252#13944
