Re: [PATCH, RFC] Enable libsanitizer on powerpc{,64}

[Konstantin Serebryany <konstantin dot s dot serebryany at gmail dot com>]

http://llvm.org/viewvc/llvm-project?rev=168369&view=rev

On Tue, Nov 20, 2012 at 7:12 PM, Evgeniy Stepanov
<eugeni.stepanov@gmail.com> wrote:
> Ok, fine.
>
>
> On Tue, Nov 20, 2012 at 6:47 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
>> On Tue, Nov 20, 2012 at 6:21 PM, Konstantin Serebryany
>> <konstantin.s.serebryany@gmail.com> wrote:
>>> On Tue, Nov 20, 2012 at 6:18 PM, Evgeniy Stepanov
>>> <eugeni.stepanov@gmail.com> wrote:
>>>> On Tue, Nov 20, 2012 at 5:52 PM, Konstantin Serebryany
>>>> <konstantin.s.serebryany@gmail.com> wrote:
>>>>>
>>>>> On Tue, Nov 20, 2012 at 5:41 PM, Peter Bergner <bergner@vnet.ibm.com>
>>>>> wrote:
>>>>> > On Tue, 2012-11-20 at 11:07 +0400, Konstantin Serebryany wrote:
>>>>> >> I've applied your patch (with minor style and comment changes)
>>>>> >> upstream:
>>>>> >> http://llvm.org/viewvc/llvm-project?view=rev&revision=168356
>>>>> >> I did not have any way to test it though. Also, gmail does something
>>>>> >> horrible with patches inlined in a message, so I might have missed
>>>>> >> something.
>>>>> >
>>>>> > Doing a quick peruse through your LLVM commit, I see you grabbed the
>>>>> > PopStackFrames() addition, but the asan_linux.cc changes do not include
>>>>> > the call to PopStackFrames() after the _Unwind_Backtrace() call.
>>>>> > Specifically, the following patch hunk:
>>>>> >
>>>>> >>      _Unwind_Backtrace(Unwind_Trace, stack);
>>>>> >> > +    // Pop off the two ASAN functions from the backtrace.
>>>>> >> > +    stack->PopStackFrames(2);
>>>>
>>>>
>>>> I wonder if under some conditions we may get a different number of extra
>>>> frames (inlining comes to mind). What do you think of removing any number of
>>>> frames that belong to the runtime library - we have memory layout info for
>>>> that?
>>>
>>> Bad idea, imho.
>>> Hard to implement, slower to run (remember, this *is* a hotspot).
>>> The frames in question are in our run-time and we can fully control inlining.
>>> What is the current number of redundant frames on ARM?
>>
>>
>> And we can have output tests that verify that we remove the right
>> number of frames.