[LLVMdev] AddressSanitizer flags in LLVM 3.5

[Alexander Tarasikov]

On Sep 26, 2014 5:33 AM, "Kostya Serebryany" <kcc at google.com> wrote:
>

Hi, Kostya. Thanks for replying

>
>
> Oh my... This is not as trivial as it sounds.
> We removed this option because (as we thought) no one was using it and
because it was actually hard to maintain.
> This is a compile-time option, which uses a different ABI, and objects
built with different flags are incompatible.
> GCC variant of asan does not support it either and GCC folks explicitly
said that they are not going to.

Thank for this. Now it makes sense. I did not actually think of it myself.

>
> I don't have a good solution. Others?
> In the meantime I would strongly suggest to try fixing the issue on the
NVIDIA side.

Unfortunately I am not working at NVIDIA so I cannot change that. But at
work we're using Nix package manager from NixOS so patching llvm, clang and
rebuilding all the packages is trivial though a bit time consuming.

>
>
>> It
>> is also interesting that OS X and FreeBSD use larger offset.
>
>
>
> Right. The small offset didn't work there for some reasons...
>
>>
>>
>> Meanwhile, those who are interested in using ASan and NVIDIA, can edit
>> "lib/Transforms/Instrumentation/AddressSanitizer.cpp" and replace
>> "Mapping.Offset = kSmallX86_64ShadowOffset" with "Mapping.Offset =
>> kDefaultShadowOffset64".
>
> you will also need to change the run-time library.

Sorry, do you mean libc or what runtime? I will take a deeper look into
llvm and clang source to make sure I didn't break anything while patching
our local tree. Basically we're now building our project with ASan and the
rest of system is not instrumented, so I think we don't have to worry about
using different offset sizes until we start instrumenting dependencies,
right?

>
> --kcc
>>
>>
>> --
>> Regards, Alexander
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>
>
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