[compiler-rt] r253483 - [PGO] Runtime support for value profiling.

[Xinliang David Li via llvm-commits]

Loop in Chris for advice.

Chris, I need a way to enable/disable use of atomic operations for profile
library build. The cmake currently defines variable LLVM_HAS_ATOMICS which
is set via 'CHECK_CXX_SOURCE_COMPILES(..)' call.  Can this variable be used
in library CMakeLists file or is it for host compilation only? If not, what
is the best alternatives? I am hesitant  to manually check each one of the
arch variants ...

thanks,

David


On Thu, Dec 3, 2015 at 3:55 PM, Xinliang David Li <xinliangli at gmail.com>
wrote:

> I have a pending patch to remove the need for sync_fetch_add operation.
> After that gets in, I will do more cleanups to make the problem go away.
>
> David
>
>
> On Thu, Dec 3, 2015 at 3:38 PM, Joerg Sonnenberger via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> On Wed, Nov 18, 2015 at 06:12:35PM -0000, Betul Buyukkurt via
>> llvm-commits wrote:
>> > Author: betulb
>> > Date: Wed Nov 18 12:12:35 2015
>> > New Revision: 253483
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=253483&view=rev
>> > Log:
>> > [PGO] Runtime support for value profiling.
>> >
>> > This change adds extends the data structures and adds in the routines
>> > for handling runtime calls for value profiling. The profile data format
>> > is modified and the version number is incremented.
>>
>> This revision has introduced a serious portability regression. Now the
>> instruction profiling code requires the present of 64bit atomics, which
>> simple don't exist on many platforms.
>>
>> Joerg
>> _______________________________________________
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>>
>
>
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