[llvm-dev] LLVM and Xeon Skylake v5

[Andy Schneider via llvm-dev]

Thank you. I'm letting it auto detect by setting the target using getProcessTarget. I disabled avx512 support by passing -avx512f (and the other variants) to setMAttrs on EngineBuilder. I can see refs to avx512 in X86.td. It's the exact same executable running on Kabylake. 

What does the Cannot select: specifically mean? Is there some table that doesn't have a definition for a key in it that I would need to patch up?

Am I answering your questions?


> On 8 May 2017, at 17:32, Craig Topper <craig.topper at gmail.com> wrote:
> 
> I can try to help.
> 
> Are you passing a CPU string or are you letting it autodetect the CPU using getHostCPUName? I don't see support detecting skylake or even avx-512 support in the autodetection code that far back. Are you doing the same thing for the i7 kabylake? How did you disable AVX-512 code gen? 
> 
> ~Craig
> 
>> On Mon, May 8, 2017 at 9:21 AM, Andy Schneider via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>> Hi,
>> 
>> I have a JIT compiler using the legacy JIT on LLVM 3.5 that, when run on the Xeon v5 Skylakes produces "Cannot select: intrinsic %llvm.x86.sse41.round.sd". Note, this does not occur on i7 Kabylakes. To get this far I had to disable AVX512 code gen.
>> 
>> Upgrading the system I am looking at from 3.5 to a later version is a big job that I'd prefer not to have on my critical path.
>> 
>> Does anyone have any tips on where I would look to debug this sort of issue? I'm new to LLVM.
>> 
>> Thanks
>> 
>> Andy
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> 
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