On 16/09/2021 07:44, manuel.serr...@inria.fr wrote:
I have conducted a very quick experiment:
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cat > bt.c <<EOF
#include <backtrace.h>
struct backtrace_state *bt_state;
static int cb(void *data, uintptr_t pc, const char *filename, int lineno, const
char *function) {
printf("%s:%d %s\n", filename ? filename : "", lineno, function ? function :
"");
return 0;
}
static void cbe(void *data, const char *msg, int errnum) {
fprintf(stderr, "%s(%)", msg, errnum);
}
long bt_init() {
bt_state = backtrace_create_state(0L, 0, cbe, 0L);
}
long bt_test() {
backtrace_full(bt_state, 0, cb, cbe, 0L);
}
EOF
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Then I grabbed the maze.scm from the bglstone suite and inserted a
call to bt_init at the beginning of the execution and a call to bt_test
in the middle of the benchmark. I have then compiled with:
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gcc -c -I ../include/ -c bt.c
bigloo -unsafe -O3 maze.scm bt.o ../lib/libbacktrace.a -cg -glines
./a.out | demangle
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I obtained
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/tmp/BT/libbacktrace/maze.scm:489 print-hexmaze@maze
/tmp/BT/libbacktrace/maze.scm:435 pmaze@maze
/tmp/BT/libbacktrace/maze.scm:805 &<@anonymous:1833>@maze
objs/obj_u/Ieee/port.c:3744 with-output-to-file@__r4_ports_6_10_1
/tmp/BT/libbacktrace/maze.scm:804 do-bench@maze
/tmp/BT/libbacktrace/maze.scm:821 main@maze
/tmp/BT/libbacktrace/maze.scm:1 bigloo_main
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Which is, I must admit, very nice. I will definitively have to look at
libbacktrace for next Bigloo releases...
Thanks again for having drawn our attention to that library that, personally,
I didn't know.
The caveats are:
* Unix signals. Ian Lance Taylor worked hard to follow
signal-safety(7)
<https://man7.org/linux/man-pages/man7/signal-safety.7.html>, but
your callbacks to libbacktrace might not follow these rules (in
particular if you call backtracing routines from inside your signal
handler)
* Tail call optimizations done by GCC (not Bigloo!)
* libbacktrace might not work properly on other OSes....
In practice, compiling on Linux with optimization and DWARF debugging
information is helpful. So gcc -O3 -g.
On Linux, dladdr(3)
<https://man7.org/linux/man-pages/man3/dladdr.3.html> could be helpful.
Hope this helps.
Cheers
--
Basile Starynkevitch <bas...@starynkevitch.net>
(only mine opinions / les opinions sont miennes uniquement)
92340 Bourg-la-Reine, France
web page: starynkevitch.net/Basile/
