r218541 - Don't link in sanitizer runtimes if -nostdlib/-nodefaultlibs is provided.

[Eric Fiselier]

Hi All,

The libc++ LIT test driver uses -nodefaultlibs so that it can properly link
against libc++ and the ABI library.
Since this patch we can no longer use sanitizers when running our test
suite since it's quite difficult to mimic the driver's behavior and
manually link in the sanitizer runtimes.

I agree with the rational behind your change.
However, since it's difficult to manually link the sanitizer runtimes, it
would be nice to have a way to force the front end to do it even when
-nodefaultlibs is present.
I think we should consider adding '-static-lib*san' flags similar to the
ones provided by GCC.

I'm not very knowledgeable about the clang linker driver so any input is
welcome.

/Eric









On Fri, Sep 26, 2014 at 3:22 PM, Alexey Samsonov <vonosmas at gmail.com> wrote:

> Author: samsonov
> Date: Fri Sep 26 16:22:08 2014
> New Revision: 218541
>
> URL: http://llvm.org/viewvc/llvm-project?rev=218541&view=rev
> Log:
> Don't link in sanitizer runtimes if -nostdlib/-nodefaultlibs is provided.
>
> It makes no sense to link in sanitizer runtimes in this case: the user
> probably doesn't want to see any system/toolchain libs in his link if he
> provides these flags, and the link will most likely fail anyway - as
> sanitizer
> runtimes depend on libpthread, libdl, libc etc.
>
> Also, see discussion in
> https://code.google.com/p/address-sanitizer/issues/detail?id=344
>
> Modified:
>     cfe/trunk/lib/Driver/Tools.cpp
>     cfe/trunk/test/Driver/sanitizer-ld.c
>
> Modified: cfe/trunk/lib/Driver/Tools.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=218541&r1=218540&r2=218541&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Driver/Tools.cpp (original)
> +++ cfe/trunk/lib/Driver/Tools.cpp Fri Sep 26 16:22:08 2014
> @@ -2243,6 +2243,10 @@ collectSanitizerRuntimes(const ToolChain
>  // C runtime, etc). Returns true if sanitizer system deps need to be
> linked in.
>  static bool addSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
>                                   ArgStringList &CmdArgs) {
> +  // Don't link in any sanitizer runtimes if we have no system libraries.
> +  if (Args.hasArg(options::OPT_nostdlib) ||
> +      Args.hasArg(options::OPT_nodefaultlibs))
> +    return false;
>    SmallVector<StringRef, 4> SharedRuntimes, StaticRuntimes,
>        HelperStaticRuntimes;
>    collectSanitizerRuntimes(TC, Args, SharedRuntimes, StaticRuntimes,
>
> Modified: cfe/trunk/test/Driver/sanitizer-ld.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/sanitizer-ld.c?rev=218541&r1=218540&r2=218541&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Driver/sanitizer-ld.c (original)
> +++ cfe/trunk/test/Driver/sanitizer-ld.c Fri Sep 26 16:22:08 2014
> @@ -301,3 +301,10 @@
>  // CHECK-LSAN-ASAN-LINUX-NOT: libclang_rt.lsan
>  // CHECK-LSAN-ASAN-LINUX: libclang_rt.asan-x86_64
>  // CHECK-LSAN-ASAN-LINUX-NOT: libclang_rt.lsan
> +
> +// RUN: %clang -nostdlib -fsanitize=address %s -### -o %t.o 2>&1 \
> +// RUN:     -target x86_64-unknown-linux \
> +// RUN:     --sysroot=%S/Inputs/basic_linux_tree \
> +// RUN:   | FileCheck --check-prefix=CHECK-NOSTDLIB %s
> +// CHECK-NOSTDLIB: "{{.*}}ld{{(.exe)?}}"
> +// CHECK-NOSTDLIB-NOT: libclang_rt.asan
>
>
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