Re: [Squeak-VMdev] Request for help with simulation in 3.7

[tim R. <ti...@su...>]

> 1.  If everything worked right, is it the case that a current system
> should be able to simulate itself?  What this means is that, provided
> that the plugin interface all works (and fails) properly, does all
> the necessary failure code exist such that the system will run
> completely and with integrity?  If this is not so, then a further
> question is, apart from whatever fixes may be needed, how much new
> code would need to be written?
> 
With the two fixes I sent you in between packing boxes and disconnecting 
  computers it should simulate about as well as can be expected right now.
As you've discovered, there are parts of some plugins which were not 
written with support for the simulator in mind.  For example, 6 methods 
send strlen: and 7 strcmp: - neither of which are simulated.

BalloonEngine>>#primInitializeBuffer: looks suspicious to me from a 
quick scan mainly because resetGraphicsEngineStats fills up 'workBuffer' 
which most likely needs to be wrapped in a CArrayAccessor in the 
BalloonEngineSimulation code. See BalloonEngineSimulation>smallSqrtTable 
for an example involving a small array.

Interpreter>primitiveTruncated fails for utterly obvious reasons - the 
line self cCode:'pushInteger((int) trunc)' inSmalltalk:[self 
pushInteger: rcvr truncated]] quite obviously doesn't do a range test on 
the truncated number and since a very large float can easily exceed an 
acceptable 32bit int, kaboom.

All of the improvements Ned (&I) proposed in april when you started 
looking at 64bitness are in the VMMaker3-7b5 package. The extra two 
fixes compensate for the latest work on dispatching direct function 
addresses in the message sending.

Aside from some places where the perpetrator of code can remember doing 
something unsimulable, the only real answer is to run till it breaks and 
find a fix each time. Ny experience is that this is tedious, time 
consuming and utterly unappreciated work that nobody cares about until 
they have a problem. Much like most VM work in fact :-)

I'm not in a position to do anything much with this for now; I'm still 
unpacking, setting up and trying to find everything.

tim