On Thu, Dec 13, 2012 at 02:22:52PM +0400, Konstantin Serebryany wrote:
> I've added two flags, both on by default for now.
>
> // Use fast (frame-pointer-based) unwinder on fatal errors (if available).
> bool fast_unwind_on_fatal;
> // Use fast (frame-pointer-based) unwinder on malloc/free (if available).
> bool fast_unwind_on_malloc;
>
>
> % clang -fsanitize=address -g
> ~/llvm/projects/compiler-rt/lib/asan/lit_tests/overflow-in-qsort.cc
> % ASAN_OPTIONS=fast_unwind_on_fatal=0 ./a.out 2>&1 | asan_symbolize.py
> / | grep '#'
> #0 0x419731 in QsortCallback overflow-in-qsort.cc:18
> #1 0x7fa7e137b61f in msort_with_tmp msort.c:143
> #2 0x7fa7e137baba in msort_with_tmp msort.c:46
> #3 0x419a58 in MyQsort overflow-in-qsort.cc:25
> #4 0x419c94 in main overflow-in-qsort.cc:33
> #5 0x7fa7e136276c in __libc_start_main libc-start.c:226
> #6 0x4193ac in _start ??:0
> % ASAN_OPTIONS=fast_unwind_on_fatal=1 ./a.out 2>&1 | asan_symbolize.py
> / | grep '#'
> #0 0x419731 in QsortCallback overflow-in-qsort.cc:18
> #1 0x7f816783f61f in msort_with_tmp msort.c:143
> %
>
> This feature still needs some love.
> I'll set fast_unwind_on_fatal to 0 after some testing and then merge
> to gcc (unless there is a rush).
I'll wait for your commit, then will test it on Fedora. msort.c and qsort.c
are definitely built with -fasynchronous-unwind-tables -fexceptions though,
at least by default.
> If we want to support new handler and allow asan's malloc to return 0,
> it is much easier and cleaner to implement it from scratch.
libstdc++ doesn't have __new_handler exported I think, and there is no way
to query it outside of libstdc++ itself though. One can only set it.
Jakub
