Re: OpenGL works! Was: Re: GCJ and OpenGL under Win32

[Sal <gcj at svf dot dreamhost dot com>]

Tom Tromey wrote:

> Sal> I finally figured the problem out.  I rebuilt the SWT OpenGL dll with
> Sal> mingw32, for some reason Sun's VM loads mangled names in JNI dlls and
> Sal> GCJ doesn't.
>
> That is strange, since we have special Windows code in our JNI
> implementation to do the mangling.  That is, if you mean mangling like
> appending "@NNN" to the function name.  Can you describe more what is
> going wrong?  What you expected, what the symbol names are, and what
> they are after you recompiled?
>
> Maybe there's a bug in our code.  If so that could even be a
> regression... what version are you using again?

Ok I'll rehash what happened in case it helps any:

I tried the application under Sun's VM, it worked fine. Then, tried to 
run a GCJ compiled OpenGL app with SWT's stock gl-win32.dll and recieved:

Exception in thread "main" java.lang.UnsatisfiedLinkError: gluPerspective
  at 0x00651f8e (Unknown Source)
  at 0x00651962 (Unknown Source)
  at 0x006528d4 (Unknown Source)
  at 0x006962e4 (Unknown Source)
[... etc ...]


Then tried to figure out what was wrong with the DLL...

Here are snippits I got using: dumpbin -exports gl-win32.dll

From 'Original' (probably msvc built) SWT OpenGL DLL:
       261  104 00004828 
_Java_org_eclipse_swt_opengl_GL_glPushClientAttrib@12
       262  105 00004835 _Java_org_eclipse_swt_opengl_GL_glPushMatrix@8
       263  106 0000483E _Java_org_eclipse_swt_opengl_GL_glPushName@12
       264  107 0000484B _Java_org_eclipse_swt_opengl_GL_glRasterPos2d@24
       265  108 00004866 _Java_org_eclipse_swt_opengl_GL_glRasterPos2dv@12


I thought maybe the leading underscore and trailing '@' confused GCJ... 
so rebuilt the DLL using mingw32:

'mingw32 enhanced' DLL:
       261  104 00007EF9 Java_org_eclipse_swt_opengl_GL_glPushClientAttrib
       262  105 00007F11 Java_org_eclipse_swt_opengl_GL_glPushMatrix
       263  106 00007F20 Java_org_eclipse_swt_opengl_GL_glPushName
       264  107 00007F38 Java_org_eclipse_swt_opengl_GL_glRasterPos2d
       265  108 00007F57 Java_org_eclipse_swt_opengl_GL_glRasterPos2dv

Using this DLL the application works.  I'm not sure why/how the Sun VM 
gets around the mangling.

Compiler info:

gcc -v
Reading specs from 
e:/dev/thisiscool-gcc/gcc-4.0/bin/../lib/gcc/i686-pc-mingw32/
4.0.0/specs
Configured with: /datal/gcc/gcc/configure 
--prefix=/datal/gcc/build/wingcc --bui
ld=i686-pc-linux-gnu --host=i686-pc-mingw32 --target=i686-pc-mingw32 
--enable-la
nguages=c,c++,java --with-gcc --with-gnu-as --with-gnu-ld 
--enable-threads=win32
--disable-nls --disable-win32-registry --disable-shared --disable-debug 
--witho
ut-newlib --enable-libgcj --disable-java-awt --without-x 
--enable-java-gc=boehm
--disable-libgcj-debug --enable-interpreter 
--enable-hash-synchronization --enab
le-sjlj-exceptions --enable-libgcj-multifile 
--enable-libgcj-mingw-osapi=ansi
Thread model: win32

gcc version 4.0.0 20040924 (experimental)

Hope this helps!!!!

- Sal