[LLVMdev] asan coverage

[Kostya Serebryany]

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
>>>>>>
>>>>>>
>>>
>