Support for Renoir Zen 2 CPUs

[jebej]

On a laptop with a Ryzen 7 4700U CPU running Windows 10, this is what is being reported (also reported on Discourse under WSL2):

julia> versioninfo()
Julia Version 1.5.0-rc2.0
Commit 7f0ee122d7 (2020-07-27 15:24 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: AMD Ryzen 7 4700U with Radeon Graphics
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-9.0.1 (ORCJIT, znver1)

julia> LinearAlgebra.versioninfo()
BLAS: libopenblas (OpenBLAS 0.3.9  USE64BITINT DYNAMIC_ARCH NO_AFFINITY Prescott MAX_THREADS=32)
LAPACK: libopenblas64_

As far as I can tell, LLVM 9 should support znver2, and OpenBLAS should as well.

[yuyichao]

#36502

[jebej]

This patch seems to have been included in rc2, which was the version I tried...

[yuyichao]

No it's not. Only the bug fix part of it was.

[jebej]

I see, so support will only come in 1.6 then?

[yuyichao]

It should be in 1.6.

[jebej]

I tried a nighly and got this:

julia> versioninfo()
Julia Version 1.6.0-DEV.548
Commit 9267bbf1fc (2020-07-27 16:57 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: AMD Ryzen 7 4700U with Radeon Graphics
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-9.0.1 (ORCJIT, btver1)

julia> LinearAlgebra.versioninfo()
BLAS: libopenblas (OpenBLAS 0.3.9  USE64BITINT DYNAMIC_ARCH NO_AFFINITY Prescott MAX_THREADS=32)
LAPACK: libopenblas64_

[yuyichao]

AFAICT our detection code is identical to LLVM's. And previously you saw a "better" result since the detection code misidentify it as zen1 and bypassing LLVM ones. If you can find out your CPUID it'll be pretty easy to add it to the list of znver2 ones.

Also, for the openblas issue, you should report to https://github.com/xianyi/OpenBLAS instead. AFAICT we are using a version witht identical AMD CPU detectiton as the latest master there.

[jebej]

CPUID:

CPUID signature: 860F01
Family: 23 (017h)
Model: 96 (060h)
Stepping: 1 (01h)

Full info uploaded to cpu-world: http://www.cpu-world.com/cgi-bin/CPUID.pl?CPUID=71632

[jebej]

Regarding OpenBLAS, that might not necessarily be their fault, on Discourse, the OP installed the package from AUR and the architecture got detected properly:

Update: I reinstalled and reconfigured the libopenblas from AUR, now the system Julia has:

julia> LinearAlgebra.versioninfo()
BLAS: libopenblas (OpenBLAS 0.3.10 NO_AFFINITY USE_OPENMP ZEN MAX_THREADS=12)
LAPACK: liblapack

EDIT: nevermind that, see OpenMathLib/OpenBLAS#2738