[Vm-dev] Shape/ABI of code jitted by cog?

Javier Pimás elpochodelagente at gmail.com
Thu Feb 15 01:32:50 UTC 2018

I've been debugging squeaknos running (crashing) inside a system vm. I
think the simulator cannot be used in this case so I guess my next best
choice will be a gdb debug stub.


On Wed, Feb 14, 2018 at 3:26 PM, Eliot Miranda <eliot.miranda at gmail.com>

> Hi Javier,
> On Wed, Feb 14, 2018 at 6:32 AM, Javier Pimás <elpochodelagente at gmail.com>
> wrote:
>> For debugging aid, I'd like to know if there is any cheatsheet with
>> things like frame layout in the native stack (offset of the compiled
>> method, the receiver, temporaries) and shape of the code (i.e. how to
>> detect where a method starts and ends).
> The first choice is how you're going to debug. You can debug the generated
> C code.  There are several printing and debug functions included in the
> generated source, and it is set up to be compiled in three variants,
> production, assert and debug.  See any of the HowToBuild files under the
> build directories.  But debugging at the C level is much more difficult and
> less productive than using the development environment, "the simulator".
> The VM is best understood, developed and debugged in Smalltalk.  You can
> create a VMMaker image containing the full environment using the
> image/buildspurtrunkvmmaker[64]image.sh scripts (32-bit or 64-bit, 64-bit
> is faster for 64-bit development).  A workspace in the image (the contents
> of image/VM Simulation Workspace.text) contains launch expressions for the
> simulator.  The simulator has three windows, the top for the Smalltalk
> display, the bottom left for a transcript, and the bottom right for
> commands.  The bottom right pane has a menu with an extensive set of debug
> commands.
> One useful thing is to browse all methods beginning with print local to
> VMMaker, especially those in the Cogit hierarchy (the JIT), the
> StackInterpreter hierarchy (the Interpreter) and the SpurMemoryManager
> hierarchy (the memory manager/GC).
> Perhaps you could tell us a little bit about what you're trying to do and
> we can try and provide some more specific information.
> Cheers,
>> Pocho
>> --
>> Javier Pimás
>> Ciudad de Buenos Aires
> _,,,^..^,,,_
> best, Eliot

Javier Pimás
Ciudad de Buenos Aires
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