[compiler-rt] r233215 - On OS X, explicitly use libc++

Kuba Brecka kuba.brecka at gmail.com
Mon Apr 13 07:56:30 PDT 2015 

ASan (and other sanitizers) have dropped support for 10.6 long time ago, the intention of the commit (and another one before) in question was to explicitly specify that via -mmacosx-version-min, and also explicitly require libc++.  Libc++ is available on 10.7+ and ASan contains several interceptors that only work in libc++ mode.

Before these commits (or if we revert), the situation is that *it depends on your system* what C++ library will ASan link against.  The minimal OS X version is also set to your *current OS*.  This makes the resulting sanitizer dylibs have subtle differences based on how/where the dylib was built.

Note that this should only apply to sanitizers - the parts of compiler-rt that are used for regular binaries are not dylibs, but .a files, and their required OS X version should be much lower.  If these .a are also affected by that patch, then that was unintentional and a bug.

Kuba

> On Apr 13, 2015, at 4:39 PM, Nico Weber <thakis at google.com> wrote:
> 
> On Sun, Apr 12, 2015 at 12:22 AM, Hans Wennborg <hans at chromium.org <mailto:hans at chromium.org>> wrote:
> +samsonov who did the Clang part in r233860
> 
> We only do one compiler-rt build, and that is used for both asan and
> regular builds, so it needs to work with both.
> 
> Nico: I assume parts of compiler-rt get linked into the target
> binaries, i.e. it's not just used for asan, right?
> 
> Yes:
> 
> $ clang test.c -v
> # ...
> "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld" ... /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/6.0/lib/darwin/libclang_rt.osx.a
> 
> Since the commit description didn't say anything about intentionally dropping support for 10.6, I think it's ok to revert this for now.
> 
> 
> On Fri, Apr 10, 2015 at 10:17 AM, Alexander Potapenko <glider at google.com <mailto:glider at google.com>> wrote:
> > I don't think we really need to require libc++ for ASan, but note that
> > ASan itself already requires 10.7.
> > Perhaps we should bump the target OS version in Chromium for asan==1?
> > (IIRC we don't have 10.6 machines on CF or bots)
> >
> > On Fri, Apr 10, 2015 at 3:07 AM, Hans Wennborg <hans at chromium.org <mailto:hans at chromium.org>> wrote:
> >> This seems to have broken Chromium's ASan build on Darwin, where we
> >> target Mac OS X 10.6 which IIUC doesn't have libc++.
> >>
> >> Is libc++ now a hard requirement of the ASan run-time?
> >>
> >> On Wed, Mar 25, 2015 at 2:07 PM, Kuba Brecka <kuba.brecka at gmail.com <mailto:kuba.brecka at gmail.com>> wrote:
> >>> Author: kuba.brecka
> >>> Date: Wed Mar 25 16:07:20 2015
> >>> New Revision: 233215
> >>>
> >>> URL: http://llvm.org/viewvc/llvm-project?rev=233215&view=rev <http://llvm.org/viewvc/llvm-project?rev=233215&view=rev>
> >>> Log:
> >>> On OS X, explicitly use libc++
> >>>
> >>> For OS X builds, both Make and CMake, let's be very explicit about using
> >>> libc++ and libc++abi with:
> >>>
> >>> 1) -stdlib=libc++ in CFLAGS and LDFLAGS for all platforms
> >>> 2) -lc++ in LDFLAGS for all platforms
> >>> 3) switch from -undefined dynamic_lookup to -lc++abi for UBSan in
> >>>    Makefile-based builds
> >>>
> >>> Reviewed at http://reviews.llvm.org/D8617 <http://reviews.llvm.org/D8617>
> >>>
> >>>
> >>> Modified:
> >>>     compiler-rt/trunk/CMakeLists.txt
> >>>     compiler-rt/trunk/make/platform/clang_darwin.mk <http://clang_darwin.mk/>
> >>>
> >>> Modified: compiler-rt/trunk/CMakeLists.txt
> >>> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/CMakeLists.txt?rev=233215&r1=233214&r2=233215&view=diff <http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/CMakeLists.txt?rev=233215&r1=233214&r2=233215&view=diff>
> >>> ==============================================================================
> >>> --- compiler-rt/trunk/CMakeLists.txt (original)
> >>> +++ compiler-rt/trunk/CMakeLists.txt Wed Mar 25 16:07:20 2015
> >>> @@ -302,10 +302,12 @@ if(APPLE)
> >>>    set(DARWIN_osx_CFLAGS -mmacosx-version-min=${SANITIZER_MIN_OSX_VERSION}
> >>>      -stdlib=libc++)
> >>>    set(DARWIN_iossim_CFLAGS
> >>> +    -stdlib=libc++
> >>>      -mios-simulator-version-min=7.0 -isysroot ${IOSSIM_SDK_DIR})
> >>>    set(DARWIN_osx_LINKFLAGS -mmacosx-version-min=${SANITIZER_MIN_OSX_VERSION}
> >>> -     -stdlib=libc++)
> >>> +    -stdlib=libc++ -lc++)
> >>>    set(DARWIN_iossim_LINKFLAGS
> >>> +    -stdlib=libc++ -lc++
> >>>      -Wl,-ios_simulator_version_min,7.0.0
> >>>      -mios-simulator-version-min=7.0
> >>>      -isysroot ${IOSSIM_SDK_DIR})
> >>>
> >>> Modified: compiler-rt/trunk/make/platform/clang_darwin.mk <http://clang_darwin.mk/>
> >>> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/make/platform/clang_darwin.mk?rev=233215&r1=233214&r2=233215&view=diff <http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/make/platform/clang_darwin.mk?rev=233215&r1=233214&r2=233215&view=diff>
> >>> ==============================================================================
> >>> --- compiler-rt/trunk/make/platform/clang_darwin.mk <http://clang_darwin.mk/> (original)
> >>> +++ compiler-rt/trunk/make/platform/clang_darwin.mk <http://clang_darwin.mk/> Wed Mar 25 16:07:20 2015
> >>> @@ -178,29 +178,27 @@ CFLAGS.10.4               := $(CFLAGS) $(OSX_DEPLOYME
> >>>  SANITIZER_MACOSX_DEPLOYMENT_ARGS := -mmacosx-version-min=10.7
> >>>  SANITIZER_IOSSIM_DEPLOYMENT_ARGS := -mios-simulator-version-min=7.0 \
> >>>    -isysroot $(IOSSIM_SDK)
> >>> -SANITIZER_CFLAGS := -fno-builtin -gline-tables-only
> >>> +SANITIZER_CFLAGS := -fno-builtin -gline-tables-only -stdlib=libc++
> >>>
> >>>  CFLAGS.asan_osx_dynamic := \
> >>>         $(CFLAGS) $(SANITIZER_MACOSX_DEPLOYMENT_ARGS) \
> >>>         $(SANITIZER_CFLAGS) \
> >>> -       -stdlib=libc++ \
> >>>         -DMAC_INTERPOSE_FUNCTIONS=1 \
> >>>         -DASAN_DYNAMIC=1
> >>>
> >>>  CFLAGS.asan_iossim_dynamic := \
> >>>         $(CFLAGS) $(SANITIZER_IOSSIM_DEPLOYMENT_ARGS) \
> >>> -  $(SANITIZER_CFLAGS) \
> >>> +       $(SANITIZER_CFLAGS) \
> >>>         -DMAC_INTERPOSE_FUNCTIONS=1 \
> >>>         -DASAN_DYNAMIC=1
> >>>
> >>>  CFLAGS.ubsan_osx_dynamic := \
> >>>         $(CFLAGS) $(SANITIZER_MACOSX_DEPLOYMENT_ARGS) \
> >>> -       $(SANITIZER_CFLAGS) \
> >>> -       -stdlib=libc++
> >>> +       $(SANITIZER_CFLAGS)
> >>>
> >>>  CFLAGS.ubsan_iossim_dynamic := \
> >>>         $(CFLAGS) $(SANITIZER_IOSSIM_DEPLOYMENT_ARGS) \
> >>> -  $(SANITIZER_CFLAGS)
> >>> +       $(SANITIZER_CFLAGS)
> >>>
> >>>
> >>>  CFLAGS.ios.i386                := $(CFLAGS) $(IOSSIM_DEPLOYMENT_ARGS)
> >>> @@ -232,10 +230,10 @@ CFLAGS.profile_ios.armv7k := $(CFLAGS) $
> >>>  CFLAGS.profile_ios.armv7s := $(CFLAGS) $(IOS_DEPLOYMENT_ARGS)
> >>>  CFLAGS.profile_ios.arm64  := $(CFLAGS) $(IOS6_DEPLOYMENT_ARGS)
> >>>
> >>> -SANITIZER_LDFLAGS := -undefined dynamic_lookup
> >>> +SANITIZER_LDFLAGS := -stdlib=libc++ -lc++
> >>>
> >>>  SHARED_LIBRARY.asan_osx_dynamic := 1
> >>> -LDFLAGS.asan_osx_dynamic := -lc++ $(SANITIZER_LDFLAGS) -install_name @rpath/libclang_rt.asan_osx_dynamic.dylib \
> >>> +LDFLAGS.asan_osx_dynamic := $(SANITIZER_LDFLAGS) -install_name @rpath/libclang_rt.asan_osx_dynamic.dylib \
> >>>    $(SANITIZER_MACOSX_DEPLOYMENT_ARGS)
> >>>
> >>>  SHARED_LIBRARY.asan_iossim_dynamic := 1
> >>> @@ -243,11 +241,11 @@ LDFLAGS.asan_iossim_dynamic := $(SANITIZ
> >>>    -Wl,-ios_simulator_version_min,7.0.0 $(SANITIZER_IOSSIM_DEPLOYMENT_ARGS)
> >>>
> >>>  SHARED_LIBRARY.ubsan_osx_dynamic := 1
> >>> -LDFLAGS.ubsan_osx_dynamic := -lc++ $(SANITIZER_LDFLAGS) -install_name @rpath/libclang_rt.ubsan_osx_dynamic.dylib \
> >>> +LDFLAGS.ubsan_osx_dynamic := $(SANITIZER_LDFLAGS) -lc++abi -install_name @rpath/libclang_rt.ubsan_osx_dynamic.dylib \
> >>>    $(SANITIZER_MACOSX_DEPLOYMENT_ARGS)
> >>>
> >>>  SHARED_LIBRARY.ubsan_iossim_dynamic := 1
> >>> -LDFLAGS.ubsan_iossim_dynamic := $(SANITIZER_LDFLAGS) -install_name @rpath/libclang_rt.ubsan_iossim_dynamic.dylib \
> >>> +LDFLAGS.ubsan_iossim_dynamic := $(SANITIZER_LDFLAGS) -lc++abi -install_name @rpath/libclang_rt.ubsan_iossim_dynamic.dylib \
> >>>    -Wl,-ios_simulator_version_min,7.0.0 $(SANITIZER_IOSSIM_DEPLOYMENT_ARGS)
> >>>
> >>>  ifneq ($(OSX_SDK),)
> >>>
> >>>
> >>> _______________________________________________
> >>> llvm-commits mailing list
> >>> llvm-commits at cs.uiuc.edu <mailto:llvm-commits at cs.uiuc.edu>
> >>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits <http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits>
> >
> >
> >
> > --
> > Alexander Potapenko
> > Software Engineer
> > Google Moscow
> 

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