[llvm-dev] [clang] Running a single testcase

[Sedat Dilek via llvm-dev]

On Mon, May 7, 2018 at 5:56 PM, Brian Cain <brian.cain at gmail.com> wrote:
>
> On Mon, May 7, 2018 at 10:46 AM, Sedat Dilek <sedat.dilek at gmail.com> wrote:
>>
>> On Mon, May 7, 2018 at 5:19 PM, Brian Cain <brian.cain at gmail.com> wrote:
>> >
>> >
>> ...
>
>
>
>>
>> >  Can you give a little more context?  What is your ultimate goal for
>> > this
>> > activity?  Why would you want to run the test in this fashion and what
>> > meaning would you attribute to the test passing or failing?
>> >
>>
>> When compiling a Linux-kernel I hit a problem in the
>> KVM/paravirtualization area and "clobbering RCX" on Debian/testing
>> AMD64.
>> The question came up, is this is a compiler bug or not.
>> Details see [1].
>>
>> Thus, I was looking for a reproducible testcase.
>> I have seen that clang ships some tests.
>> So, I was curious to run a single one.
>> Not sure if clang/test/Sema/asm.c is suitable here to see "clobbering
>> RCX" on Debian/x86-64.
>>
>
> Yes, I agree that it might not be the right test.
>
>>
>> On my host I have installed a clang-7 package from <apt.llvm.org>.
>> I wanted to test against that version.
>>
>> Does this help you?
>>
>> - Sedat -
>>
>> [1] https://lkml.org/lkml/2018/4/24/1227
>
>
> I see, yes, this is clearer now.
>
> IIUC, this test is testing clang's behavior regarding inline assembly and
> probably won't verify things like which registers are saved and restored.
>
> I think you might get resolution on this issue faster if you reduce
> native_save_fl() and its caller to a simple example that shows RCX not being
> saved.  Bonus points if you can identify any conditions that change this
> behavior -- or versions of clang that behave differently.  Then share your
> test and ask on llvm-dev and/or cfe-dev whether or not this behavior is
> expected.
>

Matthias answered in [1].

[1] https://lkml.org/lkml/2018/5/7/534