Re: [Valgrind-users] Debugging a GC with valgrind

[Dave G. <go...@mc...>]

On Jan 20, 2011, at 6:07 PM CST, john skaller wrote:

> Hmmm ..ok did some client request stuff .. looks like I found a bug in OSX!
> 
> First, what's this?
> 
> ==7005== Command: tools/flx_ls
> ==7005== 
> --7005-- warning: addVar: in range 0xcb2 .. 0xcd7 outside segment 0x100000000 .. 0x1000eefff (top)
> --7005-- warning: addVar: in range 0xcf4 .. 0xd88 outside segment 0x100000000 .. 0x1000eefff (top)
> --7005-- warning: addVar: in range 0xd89 .. 0xde1 outside segment 0x100000000 .. 0x1000eefff (top)
> ... [more] ...

Dunno.  Someone else probably does.

> Here's the bug? in OSX:
> 
> ==7005== Conditional jump or move depends on uninitialised value(s)
> ==7005==    at 0x10031BC28: pthread_rwlock_init (in /usr/lib/libSystem.B.dylib)
> ==7005==    by 0x10000161F: re2::Mutex::Mutex() (mutex.h:108)
> ==7005==    by 0x100031605: re2::RE2::Init(re2::StringPiece const&, re2::RE2::Options const&) (re2.cc:147)
> ==7005==    by 0x100031FEF: re2::RE2::RE2(std::string const&) (re2.cc:98)
> ==7005==    by 0x10000767C: flxusr::flx_ls::_init_::resume() (in tools/flx_ls)
> ==7005==  Uninitialised value was created by a heap allocation
> ==7005==    at 0x1001CA374: operator new(unsigned long) (vg_replace_malloc.c:261)
> ==7005==    by 0x1000315F2: re2::RE2::Init(re2::StringPiece const&, re2::RE2::Options const&) (re2.cc:147)
> ==7005==    by 0x100031FEF: re2::RE2::RE2(std::string const&) (re2.cc:98)
> ==7005==    by 0x10000767C: flxusr::flx_ls::_init_::resume() (in tools/flx_ls)
> ==7005== 
> 
> A rwlock (BSD) is an int. It is not initialised by re2. AFAICS it shouldn't have to be
> either, since that's what pthread_rwlock_init is for, but that routine appears
> to be doing a conditional jump on it.

Looks like a regression or variant of https://bugs.kde.org/show_bug.cgi?id=196528.

-Dave