Andreas,
I doubt that the jump table is being caused by calling through a
function pointer.
Usually I see them generated in response to switch statements or long
if-else-if
chains. However, the compiler is free to do whatever optimizations it
can. I'm speculating
that the compiler found some interesting patterns in your code, which
has a number of
if statments and ternary operators.
However, not being a real compiler expert, I can't say for certain.
You could tweak
the code and probably make the jump table go away. Any fix you made
would be somewhat
fragile, though.
James M
On Nov 27, 2007, at 8:52 AM, [EMAIL PROTECTED] wrote:
> I resend this as Chris and I got no answer so far.
>
> The issue is a pid provider probe gets rejected by Apple dtrace.
> Suspicion it is rejected due to
>
> libdtrace DEBUG: found a suspected jump table at
>
> below is a snippet of the assembly code of that function, that looks
> like a jump table plus the C preprocessor output of the
> same function.
>
> Anyone having an idea what could cause this jump table?
>
> Regards,
> Andreas
>
> ---------- Forwarded message ----------
> Date: Wed, 14 Nov 2007 19:52:51 +0100 (MET)
> From: [EMAIL PROTECTED]
> To: [email protected]
> Cc: Chris Dagdigian <[EMAIL PROTECTED]>, James McIlree <[EMAIL PROTECTED]
> >
> Subject: Re: [dtrace-discuss] [GE users] Apple Leopard has dtrace --
> anyone used
> the SGE probes/scripts yet?
>
> Hm ... the assebly of the function contains code like this
>
> movl L279-"L00000000011$pb"(%ebx,%eax,4), %eax
> addl %ebx, %eax
> jmp *%eax
> .align 2,0x90
> L279:
> .long L187-"L00000000011$pb"
> .long L188-"L00000000011$pb"
> .long L189-"L00000000011$pb"
> :
> (much more of this kind)
> :
>
> if that is meant by
>
> libdtrace DEBUG: found a suspected jump table at
> sge_mirror_process_events:323
>
> that could be the cause, but I got no idea where it comes from.
> Preprocessor output
> of the code is this
>
> sge_mirror_error __attribute__((noinline))
> sge_mirror_process_events(sge_evc_class_t *evc)
> {
> lList *event_list = ((void *)0);
> sge_mirror_error ret = SGE_EM_OK;
> static int test_debug = 0;
>
>
> static const char SGE_FUNC[] = "sge_mirror_process_events"; static
> const int xaybzc = 0; if (rmon_condition(xaybzc, 1)) rmon_menter
> (SGE_FUNC);
>
> if(prof_is_active(SGE_PROF_MIRROR))
> { prof_start_measurement(SGE_PROF_MIRROR,((void *)0)); };
>
> mir_set_num_events(0);
>
> if (evc && evc->ec_get(evc, &event_list, false)) {
> if (event_list != ((void *)0)) {
> ret = sge_mirror_process_event_list(evc, event_list);
> lFreeList(&event_list);
> }
> } else {
> ( sprintf (log_get_log_buffer(), (("qmaster alive timeout
> expired"))), sge_log(4,log_get_log_buffer(),"../libs/mir/
> sge_mirror.c",SGE_FUNC,1141) ,1) ?
> 1 : 0;
> evc->ec_mark4registration(evc);
> ret = SGE_EM_TIMEOUT;
> }
>
> if (mir_get_produce_qmaster_alive_timeout()) {
> test_debug++;
> if (test_debug > 3) {
> test_debug = 0;
> ( sprintf (log_get_log_buffer(), (("qmaster alive timeout
> expired"))), sge_log(4,log_get_log_buffer(),"../libs/mir/
> sge_mirror.c",SGE_FUNC,1150) ,1)
> ? 1 : 0;
> evc->ec_mark4registration(evc);
> ret = SGE_EM_TIMEOUT;
> }
> }
>
> if (prof_is_active(SGE_PROF_MIRROR)) {
> prof_stop_measurement(SGE_PROF_MIRROR, ((void *)0));
> (sprintf (log_get_log_buffer(), "PROF: sge_mirror processed %d
> events in %.3f s", mir_get_num_events(),
> prof_get_measurement_wallclock(SGE_PROF_MIRROR, false, ((void
> *)0))), sge_log(0, log_get_log_buffer(),"../li
> bs/mir/sge_mirror.c",SGE_FUNC,1160) ,1) ? 1 : 0;
>
>
> }
>
> if (rmon_condition(xaybzc, 1)) rmon_mexit(SGE_FUNC, "../libs/mir/
> sge_mirror.c", 1163);
> return ret;
> }
>
> Could it be the jump table is generated due to the function calls
> via function pointer are done by sge_mirror_process_events()?
>
> Regards,
> Andreas
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