Created attachment 141931 [details]
clinfo seems happy

Up to date Arch Linux, including: linux 4.18.12.arch1-1, xf86-video-amdgpu
18.1.0-1, mesa 18.2.2-1, opencl-mesa 18.2.2-1, xorg-server 1.20.1-1, and
plasma-desktop 5.13.5-1.

(Recently installed system that STARTED with: linux 4.18.9.arch1-1, mesa
18.2.1-1, and opencl-mesa 18.2.1-1.)

I have not tried AMDGPU-PRO.  (Not really interested anyway, and the Arch AUR
package for it is 17.40, which requires downgrading to linux 4.9 and Xorg
1.18.)

$ lspci -k | grep VGA
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
Ellesmere [Radeon RX 470/480/570/570X/580/580X] (rev e7)
        Subsystem: XFX Pine Group Inc. Ellesmere [Radeon RX
470/480/570/570X/580/580X]
        Kernel driver in use: amdgpu
        Kernel modules: amdgpu

It's the: XFX AMD Radeon RX 580 GTS Black Edition 8GB GDDR5 PCI Express 3.0

clinfo seems happy, see full output attached or here: http://termbin.com/iiow

See glxinfo output attached or here: http://termbin.com/lgqd

Anything using OpenCL immediately segfaults.

Everything that segfaults runs just fine if I uninstall opencl-mesa, and either
use opencl-amd (Arch linux package, which extracts OpenCL library from
AMDGPU-PRO **18.30** but allows it to run with the open source AMDGPU driver.) 
Everthing also runs fine if I instead use intel-opencl-runtime to just run off
the CPUs.

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luxmark 3.1 crashes in pipe_radeonsi.so, called by libMesaOpenCL.so.1, called
by libOpenCL.so.1.

A gdb backtrace with opencl-mesa 18.2.2 that I compiled in debug mode with
symbols is attached or here: http://termbin.com/to7v

A gdb backtrace with opencl-mesa 18.2.2 (Arch binary, so without buildtype
specified and no symbols) is here: http://termbin.com/m1yx

Setting environment variable MESA_DEBUG causes no additional output.

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Granted, IndigoBenchmark_x64_v4.0.64 crashes by calling
/usr/lib/libOpenCL.so::clGetPlatformIDs() which is ocl-icd, but without
opencl-mesa and instead with opencl-amd, it runs through it just fine.

A gdb backtrace is attached or here: http://termbin.com/junz6