On Wed, Jan 27, 2010 at 7:13 PM, K. K. Subramaniam <subbukk@gmail.com> wrote:

On Wednesday 27 January 2010 08:56:07 pm Bert Freudenberg wrote:
> On 27.01.2010, at 05:37, K. K. Subramaniam wrote:
> > On Tuesday 26 January 2010 11:09:26 pm Bert Freudenberg wrote:
> >> Well, there is a source for this of course (in the VMMaker Squeak
> >> package). Generating the C code is a manual, interactive process and
> >> requires a running Squeak installation. Making that scriptable is
> >> possible, but so far nobody has done it AFAIK
> >
> > That is because most of the builds so far have been one target (which is
> > also the host). Batch builds are needed for multiple variants (e.g
> > debug/release) or when cross-compiling (say to ARM targets).
>
> Ian does batched cross-builds. But the source is still only generated once.
>  All targets use the same generated sources.
The generated files are not the "source". To reiterate the issue raised in the
bug report -
---
the file platforms/unix/src/vm/interp.c starts with:

/* Automatically generated from Squeak on an Array(9 May 2008 11:24:03 am)
by VMMaker 3.8b6 [...]

However, I cannot identify the source file for that file. Also,
debian/copyright doesn't contain any hint how this file is generated.

Indeed.  In the Teleplace VMs we generate e.g.

/* Automatically generated by
    CCodeGenerator VMMaker-eem.524 uuid: 9b748596-0986-4ca7-ac5b-b7a050a08431
   from
    SimpleStackBasedCogit VMMaker-eem.524 uuid: 9b748596-0986-4ca7-ac5b-b7a050a08431
 */
static char __buildInfo[] = "SimpleStackBasedCogit VMMaker-eem.524 uuid: 9b748596-0986-4ca7-ac5b-b7a050a08431 " __DATE__ ;
char *__cogitBuildInfo = __buildInfo;
 
where the UUIDs are those form the Monticello package.  If the package is dirty when the source file is output it gains an asterisk:

/* Automatically generated by
    CCodeGeneratorGlobalStructure * VMMaker-eem.519 uuid: 151cad6d-ee56-4458-a45d-a5c53502b5be
   from    CoInterpreter * VMMaker-eem.519 uuid: 151cad6d-ee56-4458-a45d-a5c53502b5be
 */
static char __buildInfo[] = "CoInterpreter * VMMaker-eem.519 uuid: 151cad6d-ee56-4458-a45d-a5c53502b5be " __DATE__ ;
char *__interpBuildInfo = __buildInfo;

So we can determine both the Smalltalk source and the version of the generator that pushed out the C, or if it was an indeterminate version.  This is also available through the system parameter primitive.  Also note that tehthedate is the date of compilation, not generation, which should be immaterial.


----
The "source" for this file is in embedded in vmmaker image. The header only
states that VMMaker was used as a tool but it is not evident that this version
of VMMaker also embeds the "source" for the interpreter (and the plugins). I
realize the tool and the sources are all one big blob in Squeak, but we still
need to consider interpreter and plugins as separate units during builds.

So the questions that arise for downstream builders are :

 a) Where is the information about generating this intermediate file from the
source? (i.e. tool, makefile, batch script)
 b) What is the license on that particular source unit which was used to
generate this intermediate file? Should all plugins use the same license as the
interpreter?

In a manual process, these are all "in the head" but that doesn't help
downstream builders like Debian. In a batch process these steps are recorded
in scripts for anyone to read, follow and modify, if necessary.

Isn't "generated source" an oxymoron :-)? I would favor getting rid of these
files from version control and go directly to filing Slang changesets into
VMMaker and translating them on the fly in Makefiles. I would even support
writing unix/ and Cross/ in Slang. Let C become the assembly language in
Squeak.

Practically it is much more convenient to be able to gather all the C/C++ files together for a Vm build than it is to start form a set of C/C++ files and a Smalltalk source file and a Smalltalk image and a tool.  We keep an image containing a VMMaker in svn (in a directory image alongside platforms) and generate the vm/plugin tree form that image, updating it when VMMaker or a plugin is changed.  So a checking checks in the new source and the new image.  But if one wants to build one simply checks out the entire tree and builds, instead of having to fire up the VMMaker image.  Once Squeak is reliably headlessly scriptable across platforms one might revisit that but then you'd introduce a dependency of having to have a working VM to run VMMaker to punch out the sources, which could put a damper on developing for new platforms.

So while attractive in the abstract I think making the generated sources purely an intermediate form is a mistake.  In this case If It Ain't Broke Don't Fix It.


Subbu