[llvm-commits] [PATCH] [asan] Use zero-based shadow by default on Android

[Evgeniy Stepanov]

Good point. Both patches landed, here is another one that adds a
driver check for -pie.

On Wed, May 23, 2012 at 3:04 PM, Chandler Carruth <chandlerc at google.com> wrote:
> On Wed, May 23, 2012 at 3:58 AM, Evgeniy Stepanov
> <eugeni.stepanov at gmail.com> wrote:
>>
>> Note that this change will require building binaries with -fPIE -pie.
>> I believe there is really no way around this. We can not change shadow
>> location on a per-binary basic because of the shared runtime, and
>> there is no universal location that fit both PIE and non-PIE.
>>
>> I'm going to land this soon, then add some runtime checks to ensure
>> that the shadow does not silently override any preexisting mappings.
>
>
> I haven't looked at the patches, but it would be good to also teach the
> Clang driver to produce an error if the appropriate options are not attached
> to the compile and link commands but '-faddress-sanitizer' is.
>
>>
>>
>> On Tue, May 22, 2012 at 6:43 PM, Kostya Serebryany <kcc at google.com> wrote:
>> > Both look good, thanks!
>> > --kcc
>> >
>> > On Tue, May 22, 2012 at 6:38 PM, Evgeniy Stepanov
>> > <eugeni.stepanov at gmail.com> wrote:
>> >>
>> >> Hi,
>> >>
>> >> these patches (one to llvm, another to compiler-rt) change ASan
>> >> default shadow offset on Android to zero. This seems to marginally
>> >> improve performance of Thumb code, significantly (~5%) saves code
>> >> size, and avoids address space collisions with the main executable in
>> >> a non-ASLR case.
>> >>
>> >> Please review.
>> >>
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