exceptions and integrating intrp/jit
oliva at dcc.unicamp.br
Sat Sep 26 03:30:20 PDT 1998
Senthil Kumar <skumars at earthlink.net> writes:
> Alexandre Oliva wrote:
>> You go unwinding the stack, collecting exception information with
>> the JIT mechanism if the method is JIT compiled, or from the jmpbuf
>> linked list if the PC corresponds to code from the interpreter's
>> virtualMachine. I believe this would work.
> I am sorry, but I just do not understand what you are trying to say.
Ok, let me try again. Kaffe already has the logic to compute whether
a given PC belongs to a native method or not. I'm just suggesting
that you extend this test so that, if the PC corresponds to code
within function virtualMachine, from intrp/machine.c, you get
exception information from the jmp_buf.
> Also thanks for mentioning the exception prolouge.
Actually, I was not talking about the exception prologue, just the
function prologue. It starts with `pushl ebp', which saves the
pointer to the previous stack frame onto the stack.
> debug(("movl ebp,esp\n"));
> debug(("subl #?,esp\n")); /* Reserve size for exceptionFrame ?? */
> debug(("subl #3*SLOTSIZE,esp\n"));
> What exactly is going on?? :-)
I don't have the faintest idea :-)
> Both do jumps, the intrp, of course
> uses longjmp which is ineffecient, and the JIT does an ASM jmp
> to the handler.
The main problem is not the inefficiency of longjmp: setjmp introduces
a needless but unavoidable overhead.
mailto:oliva at dcc.unicamp.br mailto:aoliva at acm.org
Universidade Estadual de Campinas, SP, Brasil
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