[LLVMdev] asan coverage

[Bob Wilson]

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
>>> 
>>>