[Vm-dev] CogVM/StackVM fail to read in image, fine on Squeak 4.2.1 MacVM

[Stefan Marr]

Hi:

I recently added support to load images that have been saved with the 
CogVM in image format 6505 to the RoarVM.
However, now I noticed that the CogVM/StackVM crash when they are asked 
to load an image which is saved by our RoarVM.

Interestingly, the Squeak 4.2.1 and earlier are able to load this image.

To reproduce the problem, I put online an image [1] which is a stock 
Squeak4.2-10966, just downloaded, opened and saved with the RoarVM.

The Cog/StackVM fail to open it with an error in "0   
org.squeakfoundation.Squeak       0x00033462 
readImageFromFileHeapSizeStartingAt + 3058"

Interestingly, if I open the image with Squeak 4.2.1, and save it and 
then open it in Cog, Cog does not crash.
So, there might be some inconsistencies in our image loading/saving 
routines.

Could someone give it a try on a VM instrumented for debugging and 
explain me what the problem is?
There could be a bug in the RoarVM with filing out the image, but it is 
strange that Squeak 4.2.1 handles it just fine.

Thanks
Stefan

[1] http://soft.vub.ac.be/~smarr/roarvm/squeak-saved-with-rvm.zip