[Openmp-dev] Performance killer: more registers are used when multiple target regions are compiled together

[Johannes Doerfert via Openmp-dev]

Hey Ye,


will be solved (for most common cases) with 
https://reviews.llvm.org/D83271 .


~ Johannes


On 6/30/20 2:25 PM, Ye Luo via Openmp-dev wrote:
> Hi all,
> I just found when there are multiple offload regions, all the finally
> assembled kernels use equal amount registers corresponding to the kernel
> that uses the most registers. This causes all my kernels spilling registers
> and thus kills performance. This is surprising and I didn't see this
> behavior with IBM XL compiler.
> The reproducer is provided at https://bugs.llvm.org/show_bug.cgi?id=46450
> I also noticed the same issue with AOMP.
> So I'm wondering where could potentially be buggy in the compiling/linking
> flow.
> Any thoughts?
> Best,
> Ye
> ===================
> Ye Luo, Ph.D.
> Computational Science Division & Leadership Computing Facility
> Argonne National Laboratory
>
>
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