Re: [PATCH] Handle PIEs in libbacktrace

[Alexey Samsonov <samsonov at google dot com>]

(now in plain-text mode).

ASan calls this function only for global variables (not functions). It
is needed because
we use a different machinery to pass global names to ASan runtime - we
register globals
by a call from instrumented code, which also tells runtime the
(mangled) global name.

OTOH, in TSan we rely on symbolization to demangle names of global variables.

>
>  From what I can see, even when
> you are using llvm-symbolizer, sanitizer_common doesn't pass -demangle
> option to it.


-demangle defaults to "on" in llvm-symbolizer.


On Fri, Dec 6, 2013 at 12:51 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Fri, Dec 6, 2013 at 12:25 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>> On Fri, Dec 06, 2013 at 12:19:45PM +0400, Dmitry Vyukov wrote:
>>> > And the reason why check-g++ tsan.exp fails even with this patch is
>>> > that apparently tsan doesn't try to demangle the symbol names, so we get
>>> > e.g.:
>>>
>>> Demangling must be done by the symbolizer.
>>> +samsonov for this
>>
>> So why does asan_report.cc have then:
>> static const char *MaybeDemangleGlobalName(const char *name) {
>>   // We can spoil names of globals with C linkage, so use an heuristic
>>   // approach to check if the name should be demangled.
>>   return (name[0] == '_' && name[1] == 'Z')
>>              ? Symbolizer::Get()->Demangle(name)
>>              : name;
>> }
>> and uses it where it wants to demangle?
>
> I would say this is a defect. It's symbolizer responsibility.
>
>> From what I can see, even when
>> you are using llvm-symbolizer, sanitizer_common doesn't pass -demangle
>> option to it.
>
>
> It defaults to true:
> static cl::opt<bool>
> ClDemangle("demangle", cl::init(true), cl::desc("Demangle function names"));



-- 
Alexey Samsonov, MSK