Marcus Denker wrote:


> 
> Hi Travis!
> 
> Yes, you are right: the current version does not have primitives. The
> primitives are "normal" Smaltalk-To-C statically compiled methods (with
> inlined C-code).
> 
> But: The problem is that the image is not portable across architectures
> anymore. You can even run into problemes simply by re-compiling the VM
> using a different compiler. (There are pointers in the saved image to code
> generated by the C-compiler, these won't be the same on an other
> architecture)
> There are some hacks to prevent running such an image, and it tries
> hard to fix the refences, but according to Claus this never really worked
> in all cases.
> So he decided that the new VM (I think for version 5?) will have "real"
> primitives. (As an execution-mechanism, it will look the same for
> the programmer. You won't see  <primitive 224> but the code of the
> primitive...)
> He talked a little bit about the new vm some time ago, the following is
> what I understood from his description (My understanding  might not be
> entirely correct...):
> 
> The "primitive" methods are like "normal", not-yet-jitted Smalltalk methods
> (*codeptr is nil), but they have the "primitive" bit set. If such a method
> is called the first time, the vm looks up the right adress for the
> primitive and sets the *codeptr.
> 
> If the codeptr is nil and we have a non-primitive method, the jitter
> is called to produce native code. The code is held in a cache outside
> the image, and the adress of the code is stored in the codeptr.
> 
> If we compile a Method with the Smtlk-To-C Compiler, stc produces a
> C-source-file, gcc compiles this to an dll (.so), it's loaded at
> runtime (dlopen()), and the *codeptr is updated to point to the right
> function.
> 
> If the codeptr is not-nil, run the code at that adress.

In a way, I think that's too bad. I'm trying to remember the last time 
in 10 years I actually took advantage of xplatform image portability. I 
can remember two cases. I've done it many more times than that, but 
usually just for a "isn't that cool" grin. I've got two platforms 
(Squeak and VW) that have xplatform binary portability. If Claus does 
this I'll have three, but (IMO) the _best_ Smalltalk for looking at 
image/VM interaction/coupling will no longer be. Sad.

-- 
Travis Griggs
Member: 3rd Boolean State Software Collective
Key Technology
"It had better be a pretty good meeting to be better than no meeting at 
all"-- Boyd K. Packer