[llvm-dev] moving libfuzzer to compiler-rt?

[Kostya Serebryany via llvm-dev]

On Wed, Jul 12, 2017 at 3:07 PM, Johan Engelen via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> I'd like to add another perspective: LDC (LLVM D Compiler) can use
> libFuzzer and AddressSanitizer from compiler-rt, and it'd be great if
> building them would not require a fresh-built clang. I believe the only
> reason libFuzzer needs a fresh-built clang is because of the dependence on
> the sanitizer interface?
>

Not really. libFuzzer depends on the coverage instrumentation applied to
the target code.
I.e we can build libFuzzer with any compiler (even some old GCC) but we
have to use a recent clang to build the target code (including libFuzzer's
own tests).


> compiler-rt can already be built without using clang, libFuzzer is a
> little more tricky: libFuzzer depends on <sanitizer/coverage_interface.h>,
>
>


Not any more, removed in r307858.
It loosely depends on sanitizer/lsan_interface.h though


> note the angle brackets, meaning that you have to install compiler-rt's
> include files to have libFuzzer be in version-sync with the sanitizers.
> My hope is that moving libFuzzer to compiler-rt will make it possible to
> build it together with the sanitizers, so that it is a little easier to
> build it for non-clang use cases.
>
> Kind regards,
>   Johan
>
>
> On Tue, May 2, 2017 at 9:26 PM, George Karpenkov via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi All,
>>
>> Currently libfuzzer depends on (often freshly built) clang, yet the
>> dependency is not explicitly specified
>> in cmake.
>> That leads to various issues: for instance, it’s not possible to check
>> out LLVM repo and run libfuzzer
>> tests: one would often need to compile fresh clang first, and then create
>> a separate build directory,
>> where libfuzzer could be tested.
>> For the buildbot this problem is approached by grabbing a freshly built
>> binary from another buildbot
>> and using that for testing.
>>
>> Needless to say, that could be quite annoying.
>> Additionally, my recent changes start using libfuzzer from Clang driver:
>> and finding the actual archive file
>> requires some hardcoding of directory paths, as one would need to go up
>> the tree from the Clang binary
>> (in swift, for example, the situation is even worse, as the path to Clang
>> is a symlink, and getting an archive file
>> from the LLVM tree would require going quite a few levels up).
>>
>> From my understanding, all these problems can be solved entirely
>> by moving libfuzzer to compiler-rt, where (other) sanitizers already
>> reside.
>>
>> Any thoughts on the suggestion?
>>
>> It would be still possible to compile just libfuzzer with no
>> dependencies, by simply making a partial checkout from SVN,
>> and only the repo path would change.
>>
>> George
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
>
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