[LLVMdev] asan coverage

[Kostya Serebryany]

On Fri, Nov 15, 2013 at 10:16 AM, Bob Wilson <bob.wilson at apple.com> wrote:
> No, not that I am aware of.

So, if my commits did indeed trigger the failures it could be
something like binary size change that caused different code alignment
or some such
and which triggered a latent memory bug somewhere else.

It's already late evening for you now. Will you have a chance to
reapply changes today?

--kcc

>
> On Nov 14, 2013, at 10:15 PM, Kostya Serebryany <kcc at google.com> wrote:
>
>> On Fri, Nov 15, 2013 at 10:14 AM, Bob Wilson <bob.wilson at apple.com> wrote:
>>> The bit code file produced by the stage 1 compiler for one of the files in the clang driver is corrupt and causes the linker for stage 2 to crash.
>>
>> Is AddressSanitizer involved in any of the stages of the LTO build?
>>
>>>
>>> On Nov 14, 2013, at 10:13 PM, Kostya Serebryany <kcc at google.com> wrote:
>>>
>>>> What are the symptoms?
>>>>
>>>> On Fri, Nov 15, 2013 at 9:37 AM, Bob Wilson <bob.wilson at apple.com> wrote:
>>>>> I’m waiting to see if this fixes the buildbots.  Unfortunately, because they were failing all day, there are a bunch of other regressions that have come up, and I’m still working through them.  It takes quite a while to run a bootstrapped LTO clang build, so it will take a while longer.
>>>>>
>>>>> I don’t have any other useful information at this point, and I share your puzzlement about how your changes could possibly break the compiler.  My only hypothesis is some sort of memory corruption.
>>>>>
>>>>> I will keep you posted.
>>>>>
>>>>> On Nov 14, 2013, at 9:22 PM, Kostya Serebryany <kcc at google.com> wrote:
>>>>>
>>>>>> Also, when are you planing to "reapply the changes or help debug"?
>>>>>>
>>>>>> On Fri, Nov 15, 2013 at 9:15 AM, Kostya Serebryany <kcc at google.com> wrote:
>>>>>>> On Fri, Nov 15, 2013 at 7:26 AM, Bob Wilson <bob.wilson at apple.com> wrote:
>>>>>>>> Hi Kostya,
>>>>>>>>
>>>>>>>> Thanks for the heads-up on this.  I haven’t had a chance to look into the
>>>>>>>> details yet, but it looks like these patches may be breaking our
>>>>>>>> bootstrapped LTO build.  Our buildbots have been failing all day, and we’re
>>>>>>>> still trying to figure out the problem.  I’m going to speculatively revert
>>>>>>>> those changes, since they were the only patches on the buildbot blame list.
>>>>>>>> I will either reapply the changes or help debug the problem.
>>>>>>>
>>>>>>> How could this possibly affect your LTO build?
>>>>>>> The option is off by default.
>>>>>>> Do you have any details, logs, etc?
>>>>>>>
>>>>>>>>
>>>>>>>> —Bob
>>>>>>>>
>>>>>>>> On Nov 14, 2013, at 5:42 AM, Kostya Serebryany <kcc at google.com> wrote:
>>>>>>>>
>>>>>>>> Bob, Justin,
>>>>>>>>
>>>>>>>> I've just committed a poor man's coverage implementation that works with
>>>>>>>> asan.
>>>>>>>> http://llvm.org/viewvc/llvm-project?rev=194701&view=rev
>>>>>>>> http://llvm.org/viewvc/llvm-project?rev=194702&view=rev
>>>>>>>> It provides only function-level boolean coverage (i.e. no counters, just
>>>>>>>> "visited or not"),
>>>>>>>> but is very fast and very simple (no extra sections to the binary file, etc)
>>>>>>>> I've tried it for Chrome's content_shell (huge and heavy binary) and the
>>>>>>>> overhead
>>>>>>>> is negligible at both run-time and shutdown-time.
>>>>>>>>
>>>>>>>> We'll be evaluating this implementation and collecting usage stats.
>>>>>>>> Maybe we want to implement something simple like this in the Clang coverage.
>>>>>>>>
>>>>>>>> --kcc
>>>>>>>>
>>>>>>>>
>>>>>
>>>
>