Re: Removing the TARGET_* layer or not ?

[Ingo Prötel]

Hi Michael,

Michael Koch wrote:
> Hi list, hi Ingo,
>
>
>
> I just started porting/testing GNU classpath to solaris (2.6). Its not 
> really different to other unices (we currently support linux and 
> *BSD) but some things are. When I wanted to do the needed changes I 
> stumbled over the TARGET_* layer which adds (in my eyes) some 
> unneeded complexity. It makes it more hard to read the code and all 
> the stuff seem to be implemented either in target/generic or 
> target/Linux with no real rule what have to go where. It's just 
> difficult to understand. In fact I try to understand it since a long 
> time and always fail because of its "indirectness". Personally I 
> think some AUTOCONF checks would be more appropriate and would make 
> the code much more readable and bugfixable. There are some known bugs 
> in it but noone attacked them because none understands the code it 
> seems.
>
> Ingo: Now my question are you really using the TARGET_* system or is 
> it only rotting around in GNU classpath ? I really wonder if some 
> AUTOCONF macros would be more helpful for you ?

Yes, the TARGET-layer is in active use here.

The TARGET-layer has two advantages:
1. It makes JNI-code more readable,
2. It makes porting simple.

It makes JNI-code more readable because whenever a native function is called there is only one macro call. The other possibility would be that one has 
ifdefs for every system (possibly for every system+architecture) that one wants to support with this code. This would make the JNI-code difficult to 
read.

It makes porting easier in that one can reuse generic macros and only needs to override specific macros that differ for a given new system. And this 
all can happen without modifing the actual JNI-code. So the main step in porting is creating a new subdirectory in tartget name it Solaris. Copy over 
all the files in the Linux target. Add this to the include path. Then just work on the error that the compiler will find and where necessary create 
Solaris specific macros.

If there is interest we could provide our Solaris, Darwin, and MinGW 
TARGET-layer. This would probably help to understand how this layer is helpful.
In any case we can help if anyone needs help understanding the code.

> If it is consensus that noone understands the cod and its good to 
> rewrite it I can start it. Then I will do it slowly part for part and 
> try to introduce as less as possible bugs. Unfortunately there will 
> be bugs introduced. We are all humans. So this will need some testing 
> on some archs, Linux, *.BSD, AIX, Solaris ... etc.
>
> What is your opinion on the TARGET_* system ?
>
> It would be nice to get a statement from the AICAS people too as they 
> introduced it.
>
>
> Michael
>
>
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Ingo

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