[llvm-dev] Minimal glibc version supported by LLVM build

[Rui Ueyama via llvm-dev]

r314810 is reverted in r314924.

On Wed, Oct 4, 2017 at 11:24 AM, Rui Ueyama <ruiu at google.com> wrote:

> You also need to revert r314810 because it depends on that commit.
>
> On Wed, Oct 4, 2017 at 11:23 AM, Daniel Neilson <dneilson at azul.com> wrote:
>
>> Reverted: https://reviews.llvm.org/rL314922
>>
>> On Oct 4, 2017, at 1:17 PM, Philip Reames via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>> + Rui, the patch author
>>
>> Do we know what the oldest glibc which works with this patch is?
>>
>> For context, the most recent REHL 5 ships with glibc 2.5.  REHL 6 ships
>> with 2.12 and REHL ships with 2.17.  I have evidence that this breaks at
>> least on Centos 6.4 which is derived from REHL 6.
>>
>> This appears to break on anything REHL 6 (or earlier) derived.  I think
>> this patch needs to be reverted.  Thoughts?
>>
>> Philip
>>
>> On 10/04/2017 12:08 AM, Serguei Katkov via llvm-dev wrote:
>>
>> Hi All,
>>
>> The landed patch https://reviews.llvm.org/D38481 introduced the usage of
>> CPU_COUNT defined in glibc sched.h header.
>> I failed to find this symbol in sched.h of glibc version 2.5-24, so
>> compilation just fails.
>> /home/dolphin/merge-from-upstream-area/ws/pristine/lib/Support/Threading.cpp:
>> In function ‘unsigned int llvm::hardware_concurrency()’:
>> /home/dolphin/merge-from-upstream-area/ws/pristine/lib/Support/Threading.cpp:80:26:
>> error: ‘CPU_COUNT’ was not declared in this scope
>>      return CPU_COUNT(&Set);
>>                           ^
>>
>> It is buildable with newest version of glibc.
>> I tried to find a requirements for glibc version in LLVM documentation
>> but failed.
>> So I wonder whether there is such requirement or not.
>> Could anyone point me to this documentation?
>>
>> I'm trying to understand whether patch is wrong which relies on
>> availability of library but does not check the symbol itself or this
>> version of glibc is not supported.
>>
>> Thank you,
>> Serguei.
>>
>>
>>
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>>
>>
>
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