[llvm] r252825 - [ARM] Enable shrink-wrapping by default.

[Quentin Colombet via llvm-commits]

Hi,

I’ve had a quick look and the generated code looks good to me.
The prologue code in the failing example is needed only just before the call to the asan function (see attached assembly for x86).

I am guessing that ASAN has some heuristics to find the prologue code in the disassembly and that fails for the new code.
Note that the debugger just get it right!

Could you advise on what to do?

Thanks,
Q
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> On Nov 12, 2015, at 9:45 AM, Quentin Colombet <qcolombet at apple.com> wrote:
> 
> Hi Renato,
> 
> Thanks for the follow-up.
> 
> I’ll try to have a look as well, unless you beat me at it :).
> 
> Cheers,
> -Quentin
>> On Nov 12, 2015, at 5:35 AM, Renato Golin <renato.golin at linaro.org> wrote:
>> 
>> On 11 November 2015 at 23:31, Quentin Colombet via llvm-commits
>> <llvm-commits at lists.llvm.org> wrote:
>>> Author: qcolombet
>>> Date: Wed Nov 11 17:31:46 2015
>>> New Revision: 252825
>>> 
>>> URL: http://llvm.org/viewvc/llvm-project?rev=252825&view=rev
>>> Log:
>>> [ARM] Enable shrink-wrapping by default.
>>> 
>>> Differential Revision: http://reviews.llvm.org/D14357
>>> 
>>> rdar://problem/21942589
>> 
>> Quentin,
>> 
>> After bisecting, this seems to have caused:
>> 
>> http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15-full/builds/9014
>> 
>> http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15-full/builds/9014/steps/ninja%20check%201/logs/FAIL%3A%20AddressSanitizer-armhf-linux%3A%3Anull_deref.cc
>> 
>> I'm copying sanitizer folks to understand what's the change here, but
>> I'm guessing the sanitizer instrumentation didn't get inserted right,
>> with the prologue changed.
>> 
>> I'll revert for now...
>> 
>> cheers,
>> --renato
>