[llvm-dev] instrumenting device code with gpucc

[Yuanfeng Peng via llvm-dev]

Hey Jingyue,

Though I tried `opt -nvvm-reflect` on both bc files, the nvvm reflect
anchor didn't go away; ptxas is still complaining about the duplicate
definition of of function '_ZL21__nvvm_reflect_anchorv' .  Did I misused
the nvvm-reflect pass?

Thanks!
yuanfeng

On Fri, Mar 11, 2016 at 10:10 AM, Jingyue Wu <jingyue at google.com> wrote:

> According to the examples you sent, I believe the linking issue was caused
> by nvvm reflection anchors. I haven't played with that, but I guess running
> nvvm-reflect on an IR removes the nvvm reflect anchors. After that, you can
> llvm-link the two bc/ll files.
>
> Another potential issue is that your cuda_hooks-sm_30.ll is unoptimized.
> This could cause the instrumented code to run super slow.
>
> On Fri, Mar 11, 2016 at 9:40 AM, Yuanfeng Peng <
> yuanfeng.jack.peng at gmail.com> wrote:
>
>> Hey Jingyue,
>>
>> Attached are the .ll files.  Thanks!
>>
>> yuanfeng
>>
>> On Fri, Mar 11, 2016 at 3:47 AM, Jingyue Wu <jingyue at google.com> wrote:
>>
>>> Looks like we are getting closer!
>>>
>>> On Thu, Mar 10, 2016 at 5:21 PM, Yuanfeng Peng <
>>> yuanfeng.jack.peng at gmail.com> wrote:
>>>
>>>> Hi Jingyue,
>>>>
>>>> Thank you so much for the helpful response!  I didn't know that PTX
>>>> assembly cannot be linked; that's likely the reason for my issue.
>>>>
>>>> So I did the following as you suggested(axpy-sm_30.bc is the
>>>> instrumented bitcode, and cuda_hooks-sm_30.bc contains the hook functions):
>>>>
>>>> *llvm-link axpy-sm_30.bc cuda_hooks-sm_30.bc  -o inst_axpy-sm_30.bc*
>>>>
>>>> *llc inst_axpy-sm_30.bc -o axpy-sm_30.s*
>>>>
>>>> *"/usr/local/cuda/bin/ptxas" "-m64" "-O3" -c "--gpu-name" "sm_30"
>>>> "--output-file" axpy-sm_30.o axpy-sm_30.s*
>>>>
>>>> However, I got the following error from ptxas:
>>>>
>>>> *ptxas axpy-sm_30.s, line 106; error   : Duplicate definition of
>>>> function '_ZL21__nvvm_reflect_anchorv'*
>>>>
>>>> *ptxas axpy-sm_30.s, line 106; fatal   : Parsing error near '.2':
>>>> syntax error*
>>>>
>>>> *ptxas fatal   : Ptx assembly aborted due to errors*
>>>>
>>>> Looks like some cuda function definitions are in both bitcode files
>>>> which caused duplicate definition... what am I supposed to do to resolve
>>>> this issue?
>>>>
>>> Can you attach axpy-sm_30.ll and cuda_hooks-sm_30.ll? The duplication
>>> may be caused by how nvvm reflection works, but I'd like to see a concrete
>>> example.
>>>
>>>>
>>>> Thanks!
>>>>
>>>> yuanfeng
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>
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