On Tue, 12 Oct 2010, Mathieu Desnoyers wrote:
* Nils Carlson ([email protected]) wrote:
I was doing some minor fixes in UST today when I came across a small
phenomenon. Since including Davids testcase for trae_mark_tp I cannot
compile with -Wall. The compiler throws out a
tracepoint_test.o: In function `__check_tp_type':
/home/nils/devel/ust/tests/tracepoint/tracepoint_test.c:64: undefined
reference to `register_trace_ust_event_msg'
collect2: ld returned 1 exit status
Looking at the macros in include/ust/marker.h I find the function
void __check_tp_type(void) \
{ \
register_trace_##tp_name(tp_cb, call_private); \
} \
defined inside the __trace_mark_tp_counter function.
In the case of _DEFINE_MARKER_TP we don't create the register and
unregister functions as far as I can tell. And the error only occurs when
compiling with -Wall which I'm guessing is because __check_tp_type is
never called and is optimised out completely normally? If I create a void
pointer and assign the function address to it I get the error when
compiling without -Wall as well.
Mathieu: What do you think of this, does it seem reasonable? How do you
think we should fix it? Simplest would be to remove the check, I don't
know if the register and unregister functions will be used for anything?
Before we discuss this further, please check that the compiling
scenarios differ because of having -O0 and -O2.. with O2, the compiler
will remove dead code, which kills the problem. I think your -Wall test
only removes -O2.
Just to answer this one, before proceeding with David's, I can confirm
that I end up with -O0 and that everything compiles fine with
CFLAGS="-Wall -O2". So yes, this kills the problem.
/Nils
Mathieu
/Nils
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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