[Vm-dev] FT2Plugin stops working with latest version (was: Add argvec and envec to sqVirtualMachine.[ch]? (was: FT2Plugin stops working with latest version))

[David T. Lewis]

On Thu, Oct 06, 2011 at 05:00:12AM +0300, Igor Stasenko wrote:
>  
> On 6 October 2011 04:19, David T. Lewis <lewis at mail.msen.com> wrote:
> >
> >
> > On Wed, Oct 05, 2011 at 05:22:40PM +0200, Igor Stasenko wrote:
> >>
> >> On 5 October 2011 17:18, David T. Lewis <lewis at mail.msen.com> wrote:
> >> >
> >> > On Wed, Oct 05, 2011 at 11:52:49AM -0300, Esteban Lorenzano wrote:
> >> >>
> >> >> pd: Dave, please, please... if you have 5', can you see the BytesPerWord problem?
> >> >
> >> > I am traveling a lot right now but I will try. I looked at it a briefly
> >> > a couple of days ago and got myself confused :/
> >> >
> >> > Igor, perhaps you can confirm - when you build a Cog VM with FreeTypePlugin,
> >> > and when the plugin source code is using BytesPerWord (defined elsewhere,
> >> > I don't remember where at the moment), you were able to get a working
> >> > FreeTypePlugin, right? So if the code generator is producing "BytesPerWord"
> >> > in the plugin source, it should be working? Sorry for my confusion,
> >> > but I did not have time to retrace my earlier steps from building a Cog
> >> > VM to test compiling the plugin, so I can't check this right now (and
> >> > maybe I made a mistake when I was looking at it earlier).
> >> >
> >>
> >>
> >> Everything was working before you added the change for bytesPerWord method :D
> >> I don't know what is the problem right now, (i thought we're fixed it
> >> after discussing few weeks ago..) because i am not working on VM
> >> builds right now.
> >> So, Esteban, it is your call :D
> >>
> >
> > OK, back to Esteban's original question about getting FreetypePlugin working.
> >
> > I said earlier that I had built and tested a FreetypePlugin on Cog, but
> > this is wrong. The plugin compiled successfully, and in loaded into my
> > Squeak image when I tried it (based on 'Smalltalk listLoadedModules'), so
> > I thought that it was working. However, the build process that I used was
> > the the original unix/config/configure process, and this apparently is not
> > working correctly for FreetypePlugin (the actual FT2Plugin.c code is not
> > included in the build).
> >
> > Therefore - I cannot confirm that this works on Cog. All I can say for
> > sure is that the code generator changes that I provided produce the
> > "BytesPerWord" output that would normally be used in the oscog branch,
> > which would be the same as the code that apparently originally worked
> > when Igor built a Cog VM prior to these changes.
> >
> > Igor, whenever you next build some VMs, can you please check and see
> > if the FreetypePlugin is running correctly (not just loading, but
> > actually doing something)? If so, there must be something different
> > in your build procedure compared to what Esteban is doing.
> >
> 
> I had error reports that build is broken on jenkins server , and the
> problem is undefined bytes-per-word thingy.
> If you look at
> 
> https://ci.lille.inria.fr/pharo/view/Cog/job/Cog-Mac-Carbon/9/console
> 
> linking C shared library
> /Users/hudson/jenkins/workspace/Cog-Mac-Carbon/cog/results/CogVM.app/Contents/Resources/libFT2Plugin.dylib
> Undefined symbols:
>   "_bytesPerWord", referenced from:
>       _ftHandleValueFromReceiver in FT2Plugin.c.o
>       _primitiveLoadGlyphSlotFromFace in FT2Plugin.c.o
> ld: symbol(s) not found

This just means that the image that did the code generation did not
have the code generator patch for BytesPerWord, so of course it will
not work.  The "self bytesPerWord" in Smalltalk needs to be translated
as "BytesPerWord" for Cog. But the question is whether the BytesPerWord
macro is defined for plugins in the oscog branch. I suspect that the
answer is no, and that is why Esteban cannot get the plugin to work.

But now I think I see the problem. The BytesPerWord macro is generated
by CCodeGenerator>>emitCConstantsOn: which eliminates all unused constants
before generating them as macros in the C source for FreeTypePlugin.
When we use "self bytesPerWord", the BytesPerWord variable is not
directly referenced by the plugin, and therefore the macro does not
get generated in FreetypePlugin.c. So we need a way to convince
CCodeGenerator not to treat BytesPerWord as unreferenced.

So that is the problem ... just need to think of a solution now.

Dave