[kaffe] About ARM JIT's Exception Handling in Kaffe

[Dalibor Topic]

Bytecode wrote:
> I'm porting Kaffe to an ARM-like processor. Now JIT works OK.  I find an
> error in JIT for ARM in my porting work.

Hi,

thanks for your bug report & the endurance to find the problem.

> But if we use GCC's O2 option to compile Kaffe, GCC will optimize the
> prologue of the two functions (throwExternalException and buildStackTrace)
> and thus destroy the stack trace structure. You can use GCC -O2 -S to
> compile some programs and find that FP register disappears in the prologue
> of the function.
> (I trace the error for several days.  I am cracy:). Finally I disassembled
> the libkaffe.so and read the assemble code of the two functions. I find the
> bug!)
> 
> So we must not use O2 option to compile exception.c and stackTrace.c. 
> 
> Any suggestion is welcome.

ouch. Some kaffe ports ports explicitely pass -fno-omit-frame-pointer to 
gcc in config.frag. I've created such a patch for arm-linux. Could you 
give it a try to see if that fixes the problem of the missing fp for you?

cheers,
dalibor topic
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Index: config/arm/linux/config.frag
===================================================================
RCS file: /cvs/kaffe/kaffe/config/arm/linux/config.frag,v
retrieving revision 1.7
diff -u -r1.7 config.frag
--- config/arm/linux/config.frag	4 Aug 2003 09:20:01 -0000	1.7
+++ config/arm/linux/config.frag	20 Oct 2004 16:44:23 -0000
@@ -4,7 +4,7 @@
 #
 # in ARM gcc characters are by default unsigned
 #
-CFLAGS="$CFLAGS -fsigned-char"
+CFLAGS="$CFLAGS -fsigned-char -fno-omit-frame-pointer"
 
 # if we use cross environment, following values may not be detected.
 if [ "$cross_compiling" = yes ]; then