From lgvidal at gmail.com  Mon Jun 10 17:08:50 2019
From: lgvidal at gmail.com (lgvidal)
Date: Mon, 10 Jun 2019 12:08:50 -0500 (CDT)
Subject: [Vm-beginners] Calling VM C functions from cogged primitives
Message-ID: <1560186530194-0.post@n4.nabble.com>

Hello!

We've been working with storing some object metadata on instance variable
assignments (i.e. the assigned object's class). Doing so in the "Stack VM"
meant adding some code to certain primitives, we now find ourselves failing
to extend this functionality to the Cog VM (StackToRegisterMappingCogit).

As a proof of concept, we decided to use non-inlined C versions of the
methods we defined for the Stack VM in the cogged primitives. We tried
defining a new trampoline (with 3 arguments and no return) for this and then
generating calls to it from the cogged primitive generators, but to no
avail. 

Is this the way to go or is there an easier way to call a VM C function from
a cogged primitive?
Is there any documentation on how to define and use a new trampoline?

Thanks in advance!
Leandro




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Sent from: http://forum.world.st/Smalltalk-VM-Beginners-f3068605.html

From eliot.miranda at gmail.com  Mon Jun 10 22:45:52 2019
From: eliot.miranda at gmail.com (Eliot Miranda)
Date: Mon, 10 Jun 2019 15:45:52 -0700
Subject: [Vm-beginners] Calling VM C functions from cogged primitives
In-Reply-To: <1560186530194-0.post@n4.nabble.com>
References: <1560186530194-0.post@n4.nabble.com>
Message-ID: <CAC20JE2Q4R=LEiafyMj586=tU+qSXO=hgkZYi+u9P4Rs-EP3Jw@mail.gmail.com>

Hi Leandro,

On Mon, Jun 10, 2019 at 10:08 AM lgvidal <lgvidal at gmail.com> wrote:

> Hello!
>
> We've been working with storing some object metadata on instance variable
> assignments (i.e. the assigned object's class). Doing so in the "Stack VM"
> meant adding some code to certain primitives, we now find ourselves failing
> to extend this functionality to the Cog VM (StackToRegisterMappingCogit).
>
> As a proof of concept, we decided to use non-inlined C versions of the
> methods we defined for the Stack VM in the cogged primitives. We tried
> defining a new trampoline (with 3 arguments and no return) for this and
> then
> generating calls to it from the cogged primitive generators, but to no
> avail.
>

Have you looked at the delivery of the #attemptToAssign:withIndex: message
used to report a read-only object modification error?  his code works and
has been in production in both the StackInterpreter and the Cogit for over
a year now.

Browse references to VMBasicConstants' #IMMUTABILITY class var, e.g.

self systemNavigation browseAllCallsOn: (VMBasicConstants bindingOf:
#IMMUTABILITY)


> Is this the way to go or is there an easier way to call a VM C function
> from
> a cogged primitive?
>

This is the way to go.  But it has to be done just so :-).  Follow the
scheme used for  #attemptToAssign:withIndex: and you should do OK.


> Is there any documentation on how to define and use a new trampoline?
>

No, only the examples in the system.  Some errors should be straight-toward
to fix; the various implementations of numTrampolines must compute a large
enough trampoline table.  Other errors, such as failure to provide a valid
continuation on returning from the "send back" may be more difficult.  I'm
here to help.


> Thanks in advance!
> Leandro
>
> --
> Sent from: http://forum.world.st/Smalltalk-VM-Beginners-f3068605.html
> _______________________________________________
> VM-beginners mailing list
> VM-beginners at lists.squeakfoundation.org
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>


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_,,,^..^,,,_
best, Eliot
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