bug#16304: Upcoming clang-3.4 apparently miscompiles coreutils.

[Andrew Trick]

My previous reply didn’t have Bill’s correct email.

On Dec 31, 2013, at 11:42 AM, Andrew Trick <address@hidden> wrote:

> 
> On Dec 31, 2013, at 11:39 AM, Markus Trippelsdorf <address@hidden> wrote:
> 
>> On 2013.12.31 at 11:12 -0800, Andrew Trick wrote:
>>> 
>>> On Dec 30, 2013, at 1:47 PM, Markus Trippelsdorf <address@hidden> wrote:
>>> 
>>>> On 2013.12.30 at 18:47 +0000, Pádraig Brady wrote:
>>>>> On 12/30/2013 12:32 PM, Markus Trippelsdorf wrote:
>>>>>> coreutils-8.22 build with clang-3.4 doesn't copy permissions correctly:
>>>>>> 
>>>>>> address@hidden tmp % touch test1
>>>>>> address@hidden tmp % chmod 600 test1
>>>>>> address@hidden tmp % ls -al test1
>>>>>> -rw------- 1 markus markus 0 Dec 30 13:25 test1
>>>>>> address@hidden tmp % /var/tmp/coreutils-8.22/src/cp test1 test2
>>>>>> address@hidden tmp % ls -al test2
>>>>>> ---------- 1 markus markus 0 Dec 30 13:25 test2
>>>>>> address@hidden tmp %
>>>>> 
>>>>> Ouch.
>>>>> 
>>>>> Note as part of the 8.22 release process
>>>>> I did verify that `make check` passed with
>>>>> clang-3.3-3.fc20.x86_64
>>>>> 
>>>>> I've again verified that clang-3.3 passes your test above.
>>>>> 
>>>>> Can you pinpoint the erroneous code?
>>>>> It does seem like a clang regression TBH.
>>>> 
>>>> Started with LLVM r192750 (Enable MI Sched for x86).
>>>> I've opened a LLVM bug here:
>>>> http://llvm.org/bugs/show_bug.cgi?id=18346
>>>> 
>>>> (I will try to come up with a testcase after the holidays)
>>> 
>>> To determine whether a bug exists in MI scheduler pass (or downstream) you 
>>> can do this:
>>> -mllvm -enable-misched=false.
>>> 
>>> Duncan committed a post-3.4 fix, r197503, for a varargs bug exposed by
>>> changes to the SD scheduling policy.
>> 
>> Yes, r197503 fixes the issue. Would be nice to get the fix applied
>> before 3.4 gets released...
> 
> Yep, it would be nice. But the fix was considered too late 2 weeks ago, so 
> it’s even less likely now. I don’t think there’s any way to rerun validation 
> at this point. I’m copying Bill who is the authority.
> 
> -Andy