[cfe-commits] r169328 - in /cfe/trunk: lib/Driver/Tools.cpp test/Driver/asan-ld.c

[Kostya Serebryany]

+asan/tsan/msan folks

That's not as simple as this, I afraid.
In *san there are two different kinds of interceptors.
1. foo from libc/libstc++ is completely replaced with foo from asan.
Example: malloc, operator new
2. foo from libc/libstc++ is wrapped, such that when a user calls foo it
calls the asan copy, but then the asan function calls the original foo.
Example: pthread_create, __cxa_throw

This change allows to use -static-libstdc++ with asan w/o link failures,
but asan is still broken for -static-libstdc++ in a subtle way (since the
__cxa_throw is not intercepted, asan will have rare false positives in
presence of exceptions).
Tsan also intercepts __cxa_guard in the similar way, so it will have false
positives on function scope statics.

Do we really care that much about linking asan with static libstdc++?

--kcc


On Wed, Dec 5, 2012 at 2:54 AM, Chandler Carruth <chandlerc at gmail.com>wrote:

> Author: chandlerc
> Date: Tue Dec  4 16:54:37 2012
> New Revision: 169328
>
> URL: http://llvm.org/viewvc/llvm-project?rev=169328&view=rev
> Log:
> Add -whole-archive around the ASan runtime archive in the link command.
>
> This ensures that even though it comes first, we pick up its .o files.
> Note that if we can use this (or something similar / equivalent) on
> other platforms, we could potentially remove
> ReplaceOperatorsNewAndDelete from the ASan runtimes.
>
> We should probably do something similar for TSan and MSan as well.
>
> Modified:
>     cfe/trunk/lib/Driver/Tools.cpp
>     cfe/trunk/test/Driver/asan-ld.c
>
> Modified: cfe/trunk/lib/Driver/Tools.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=169328&r1=169327&r2=169328&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Driver/Tools.cpp (original)
> +++ cfe/trunk/lib/Driver/Tools.cpp Tue Dec  4 16:54:37 2012
> @@ -1524,8 +1524,14 @@
>        // The ASan runtime needs to come before -lstdc++ (or -lc++,
> libstdc++.a,
>        // etc.) so that the linker picks ASan's versions of the global
> 'operator
>        // new' and 'operator delete' symbols. We take the extreme (but
> simple)
> -      // strategy of inserting it at the front of the link command.
> -      CmdArgs.insert(CmdArgs.begin(), Args.MakeArgString(LibAsan));
> +      // strategy of inserting it at the front of the link command. It
> also
> +      // needs to be forced to end up in the executable, so wrap it in
> +      // whole-archive.
> +      SmallVector<const char*, 3> PrefixArgs;
> +      PrefixArgs.push_back("-whole-archive");
> +      PrefixArgs.push_back(Args.MakeArgString(LibAsan));
> +      PrefixArgs.push_back("-no-whole-archive");
> +      CmdArgs.insert(CmdArgs.begin(), PrefixArgs.begin(),
> PrefixArgs.end());
>        CmdArgs.push_back("-lpthread");
>        CmdArgs.push_back("-ldl");
>        CmdArgs.push_back("-export-dynamic");
>
> Modified: cfe/trunk/test/Driver/asan-ld.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/asan-ld.c?rev=169328&r1=169327&r2=169328&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Driver/asan-ld.c (original)
> +++ cfe/trunk/test/Driver/asan-ld.c Tue Dec  4 16:54:37 2012
> @@ -19,7 +19,7 @@
>  //
>  // CHECK-LINUX-CXX: "{{.*}}ld{{(.exe)?}}"
>  // CHECK-LINUX-CXX-NOT: "-lc"
> -// CHECK-LINUX-CXX: libclang_rt.asan-i386.a"
> +// CHECK-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.asan-i386.a"
> "-no-whole-archive"
>  // CHECK-LINUX-CXX: "-lpthread"
>  // CHECK-LINUX-CXX: "-ldl"
>  // CHECK-LINUX-CXX: "-export-dynamic"
> @@ -32,7 +32,7 @@
>  //
>  // CHECK-LINUX-CXX-STATIC: "{{.*}}ld{{(.exe)?}}"
>  // CHECK-LINUX-CXX-STATIC-NOT: stdc++
> -// CHECK-LINUX-CXX-STATIC: libclang_rt.asan-i386.a"
> +// CHECK-LINUX-CXX-STATIC: "-whole-archive"
> "{{.*}}libclang_rt.asan-i386.a" "-no-whole-archive"
>  // CHECK-LINUX-CXX-STATIC: stdc++
>
>  // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
>
>
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