Re: [xmlvm-users] "java_lang_System.h" is missing

[Arno P. <ar...@pu...>]

here a little update on the C backend. If you check the repository you 
will notice that a lot of work has happened over the last couple of 
weeks. Overall the Java to C language cross-compiler is much more 
complete than the existing Objective-C backend. To answer one of your 
questions: I believe the C backend is quite usable! One thing that is 
missing are the Cocoa wrappers, so while you can generate C code, you 
can't really use it for developing iOS applications yet. But we are 
working on it and hope to make fast progress.

To answer your question about java_lang_System.h: for the Objective-C 
backend we require hand-written versions of J2SE classes such as 
java.lang.System. For the C backend, we simply cross-compile OpenJDK to 
C! This gives us *much* better coverage compared to the Objective-C backend.

If you want to give it a little spin, try this:

- check out the latest version of XMLVM in Eclipse (the ant script
   is not yet up-to-date and we rely on Eclipse to compile certain parts
   of XMLVM).
- In a shell, do the following:

cd trunk/xmlvm
ant
# This will cross-compile ReflectionTest.java plus all
# dependent J2SE classes to directory 'out'
java -Xmx508m -jar dist/xmlvm.jar --target=c --exp-load-deps \
   --dep-optimization-config=lib/redlist.txt \
   --in=bin/org/xmlvm/test/ReflectionTest.class \
   --in=bin-util/ --out=out
cp src/xmlvm2c/compat-lib/java/* out
mv out/xmlvm.m out/xmlvm.c
gcc -std=c99 -w -DXMLVM_NO_GC out/*.c
./a.out

Note that the 'out' directory contains all static dependencies from J2SE 
that were automatically cross-compiled from OpenJDK (over 700 classes!). 
As the first of the XMLVM demos, you can use the C backend to 
cross-compile iFireworks:

cd demo/iphone/ifireworks
ant
cd -
java -Xmx500m -jar dist/xmlvm.jar --target=iphone-c \
   --app-name=iFireworks    --exp-load-deps \
   --dep-optimization-config=lib/redlist.txt \
   --resource=demo/iphone/ifireworks/res/ \
   --in=demo/iphone/ifireworks/build/classes/ \
   --in=bin-util/ --out=out1
open out1/dist/iFireworks.xcodeproj

Note that we generate portable C code. ReflectionTest can be compiled 
anywhere you have a C compiler because it is a simple console 
application. The iFireworks demo is iOS specific and requires Xcode.

I think the C backend will prove to be of huge benefit: more efficient 
code, better J2SE coverage, and last but not least, a proper garbage 
collector. We will keep you guys posted on our progress.

Arno





On 1/4/11 8:12 PM, Wenjing Yan wrote:
> Hello everyone,
>
> I am new to XMLVM, but I am quite interested in its new C target.
>
> I checked out the latest version from repository, but there was an error
> when I used "ant" to compile the fresh version, as follows:
>
>       [java] java.lang.ExceptionInInitializerError
>       [java] at
> org.apache.tools.ant.taskdefs.ExecuteJava.execute(ExecuteJava.java:194)
>       [java] at org.apache.tools.ant.taskdefs.Java.run(Java.java:771)
>       [java] at
> org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:221)
>       [java] at
> org.apache.tools.ant.taskdefs.Java.executeJava(Java.java:135)
>       [java] at org.apache.tools.ant.taskdefs.Java.execute(Java.java:108)
>       [java] at
> org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
>       [java] at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
>       [java] at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>       ... ... ...
>
> Could you please tell me what is the problem here?
>
> Another question is that I can't find "java_lang_System.h" file in the
> subdirectory "src/xmlvm2c", where only has "java_lang_System.c". Where
> is the .h file? I can only find that "java_lang_System.h" is in
> "src/xmlvm2objc".
>
> My last question is whether the new C target is stable enough to be used?
>
> Thank you.
>
> --
> /Best Regards
> Wenjing Yan/
>
>
>
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