[LLVMdev] Debugging atom builds?

[Timur Iskhodzhanov]

2013/4/3 David Tweed <david.tweed at arm.com>:
> Hi,
>
> As someone working on ARM, we're interested in this sort of issue, to which
> there's not yet a complete solution. Some advice below:
>
>
> 2013/4/3  <llvm.buildmaster at lab.llvm.org>:
>> The Buildbot has detected a new failure on builder
> clang-atom-d2700-ubuntu-rel while building llvm.
>> Full details are available at:
>>  http://lab.llvm.org:8011/builders/clang-atom-d2700-ubuntu-rel/builds/7852
>>
>> Buildbot URL: http://lab.llvm.org:8011/
>>
>> Buildslave for this Build: atom1-buildbot
>>
>> Build Reason: scheduler
>> Build Source Stamp: [branch trunk] 178634
>> Blamelist: timurrrr
>>
>> BUILD FAILED: failed check-all
>
> | Can you suggest me a way to debug this without an access to Atom D2700?
>
> The first thing to do is not assume it's necessarily machine specific, so go
> to the build that's failed and look at the "configure" stdio output and see
> what the arguments are. It might be that if you use those arguments (when
> they aren't completely unsupported on your architecture) to configure and
> see if you get the same failure. I see that the args include
> "--enable-optimized --enable-assertions": is that what you were testing?
Yes =\

> If that still doesn't work you can look at the stdio file for the actual tests
> and search for "FAILED" to at least see what happened in detail (looks like
> a different instruction was emitted).
Sure, just wanted to know how I can repro this locally to write better checks.

Probably I can pass some special flag to llc to
a) repro the Atom behavior locally
b) explicitly tell llc to use some specific target arch, making the
output Atom-independent

> I ran "make check-all" on my Ubuntu box before committing and yet the
> Ubuntu Atom bot went red.
> | Is there any way we could write test in a cross-platform way? (i.e. if
> | a test passes in one setup, it will pass with any other setup)
>
> As above, it's not necessarily just a "platform" thing; configure options
> can also affect processing enough to cause issues. These you can at least
> try on your system. But in terms of cross-platform tests, it doesn't seem
> possible because while half the time the breakage is "trivial differences
> that only crop up when you try to write a test", half the time the
> differences reflect a platform difference that would also affect real code.
> This clearly isn't ideal, but I guess we'd rather hear about platforms where
> stuff doesn't work earlier rather than later.
I totally agree we should know about problems earlier rather than later.

[I'm relatively new to LLVM development, so I might be wrong below]
I'd usually expect tests to work exactly the same way on all platforms.
If there are things that must be handled differently on different
platforms, I'd expect those to have a separate test for each platform
with explicit flags for each of these platforms.

> Cheers,
> Dave
>
>
>