On Sun, Dec 02, 2012 at 10:21:02AM +0400, Alexander Potapenko wrote:
> Hi Jack,
>
> IIUC the wrappers for dispatch_async_f, dispatch_sync_f and other
> dispatch_smth_f do not need blocks support in the compiler, since
> regular functions are passed into them. So you may want to add the
> dynamic interceptors for those back.
Alex,
This seems to only require the readjustment of the preprocessor
statements in libsanitizer/asan/dynamic/asan_interceptors_dynamic.cc.
I'll post the revised patch as soon as regression testing is finished.
> The remaining problem is that dispach_async and other functions using
> blocks won't be intercepted. This may lead to assertion failures in
> big projects (e.g. we needed those for Chrome).
In theory that is a problem, however my understanding was that the asan
dispatch support was added for use by objc/obj-c++ code. The objc/obj-c++
in FSF gcc is very fragile, on later darwin, since it runs against the
system Objective-C runtime but the compiler is only based on a merge
of the remaining bits of code from the old FSF gcc Apple branch circa
2006. IMHO, it is insane to try to do any production work with our
objc/obj-c++ compiler and current Mac OS X releases.
> Overall, the change looks good. Do you want me to backport
> MISSING_BLOCKS_SUPPORT into the LLVM version of the runtime?
Yes, as it should be transparent to llvm's builds.
Jack
>
> Alex
>
> On Sun, Dec 2, 2012 at 6:43 AM, Jack Howarth <howa...@bromo.med.uc.edu> wrote:
> > The attached patch eliminates PR 55521/sanitizer by switching libasan on
> > darwin
> > from using mach_override to mac function interposition via the importation
> > of the
> > asan/dynamic/asan_interceptors_dynamic.cc file from llvm.org's compiler-rt
> > svn.
> > The changes involve defining USING_MAC_INTERPOSE in configure.ac rather than
> > rather than USING_MACH_OVERRIDE, introduction of the use of
> > USING_MAC_INTERPOSE
> > in Makefile.am to avoid building the interception subdirectory, the passage
> > of
> > -DMAC_INTERPOSE_FUNCTIONS in asan/Makefile.am when USING_MAC_INTERPOSE as
> > well as
> > the introduction of a -DMISSING_BLOCKS_SUPPORT flag to disable code that
> > requires
> > blocks support which FSF gcc lacks. The depreciated usage of
> > USING_MACH_OVERRIDE
> > is also removed from interception/Makefile.am. Bootstrapped on
> > x86_64-apple-darwin10,
> > x86_64-apple-darwin11 and x86_64-apple-darwin12. Passes...
> >
> > make -k check RUNTESTFLAGS="asan.exp --target_board=unix'{-m32,-m64}'"
> >
> > and fixes the previously failing cond1.C test case from PR55521 on all
> > three targets.
> > Okay for gcc trunk?
> > Jack
> >
>
>
>
> --
> Alexander Potapenko
> Software Engineer
> Google Moscow
