Segmentation fault when mixing OpenGL and OpenCL

[athas]

I'm mostly curious about whether other users of nixos-rocm have seen this. When mixing OpenGL and OpenCL in the same program, I get a segmentation fault deep inside LLVM.

glut.c for reproduction:

#include <GL/glut.h>
#include <CL/cl.h>
#include <assert.h>

int main(int argc, char *argv[]) {
  cl_int err;
  cl_platform_id platform;
  err = clGetPlatformIDs(1, &platform, NULL);
  assert(err == CL_SUCCESS);

  glutInit(&argc, argv);

  return 0;
}

Compile with:

$ nix-shell -p rocm-opencl-runtime -p freeglut -p mesa_glu --run 'gcc glut.c -o glut -lOpenCL -lOpenGL -lglut -g'

I get a segfault on glutInit(). If I do glutInit() first, then I get a segfault on clGetPlatformIDs().

This happens both with ROCm 2.10, and the WIP ROCm 3.0.

[athas]

At some point in the past (a few months ago), this worked, but I don't recall the exact versions anymore.

[acowley]

Your reproducer segfaults for me, too, but I don't have much clue as to where the problem is. I guess we've got a few different versions of LLVM at play, so I tried rebuilding mesa with rocm-llvm, but that failed with what looks like a breaking change in LLVM. I'm not sure if that's the right avenue to pursue, but it's the first thing that came to mind.

[athas]

It works with NixOS 19.09 (that is, stable) and master nixos-rocm.

[athas]

I have a vague suspicion about what may be going on. Even the following program crashes when linked with -lOpenCL and run in oclgrind:

#include <GL/glut.h>
#include <assert.h>

int main(int argc, char *argv[]) {
  glutInit(&argc, argv);
  return 0;
}

The strack trace is very suspicious:

#0  0x00007ffff74f7f57 in llvm::StringMapImpl::LookupBucketFor(llvm::StringRef) () from /nix/store/vjm3m5w63kpl1bkw0gspsadnvi6zqs3i-oclgrind-19.10/lib64/liboclgrind.so
#1  0x00007ffff74cacb5 in llvm::cl::Option::setArgStr(llvm::StringRef) () from /nix/store/vjm3m5w63kpl1bkw0gspsadnvi6zqs3i-oclgrind-19.10/lib64/liboclgrind.so
#2  0x00007fffeee4e94d in __static_initialization_and_destruction_0(int, int) [clone .constprop.0] () from /nix/store/y6i4y94y5c7qqnvjx5z97dmrc25icsyj-llvm-9.0.1-lib/lib/libLLVM-9.so
#3  0x00007ffff7fe301a in call_init (l=<optimized out>, argc=argc@entry=1, argv=argv@entry=0x7fffffffcf08, env=env@entry=0x7fffffffcf18) at dl-init.c:72
#4  0x00007ffff7fe3116 in call_init (env=0x7fffffffcf18, argv=0x7fffffffcf08, argc=1, l=<optimized out>) at dl-init.c:30
#5  _dl_init (main_map=main_map@entry=0x448f50, argc=1, argv=0x7fffffffcf08, env=0x7fffffffcf18) at dl-init.c:119
#6  0x00007ffff7fe6f23 in dl_open_worker (a=a@entry=0x7fffffffb940) at dl-open.c:510
#7  0x00007ffff7decdac in __GI__dl_catch_exception (exception=<optimized out>, operate=<optimized out>, args=<optimized out>) at dl-error-skeleton.c:196
#8  0x00007ffff7fe67fa in _dl_open (file=0x7fffffffbbc0 "/run/opengl-driver/lib/dri/radeonsi_dri.so", mode=-2147483390, caller_dlopen=0x7ffff45ceace <loader_open_driver+414>,
    nsid=<optimized out>, argc=1, argv=0x7fffffffcf08, env=0x7fffffffcf18) at dl-open.c:592
#9  0x00007ffff7cba246 in dlopen_doit (a=a@entry=0x7fffffffbb60) at dlopen.c:66
#10 0x00007ffff7decdac in __GI__dl_catch_exception (exception=exception@entry=0x7fffffffbb00, operate=<optimized out>, args=<optimized out>) at dl-error-skeleton.c:196
#11 0x00007ffff7dece1f in __GI__dl_catch_error (objname=0x4052b0, errstring=0x4052b8, mallocedp=0x4052a8, operate=<optimized out>, args=<optimized out>) at dl-error-skeleton.c:215
#12 0x00007ffff7cba8f5 in _dlerror_run (operate=operate@entry=0x7ffff7cba1f0 <dlopen_doit>, args=args@entry=0x7fffffffbb60) at dlerror.c:170
#13 0x00007ffff7cba2c6 in __dlopen (file=<optimized out>, mode=<optimized out>) at dlopen.c:87
#14 0x00007ffff45ceace in loader_open_driver () from /run/opengl-driver/lib/libGLX_mesa.so.0
#15 0x00007ffff45bbd31 in driOpenDriver () from /run/opengl-driver/lib/libGLX_mesa.so.0
#16 0x00007ffff45c4340 in dri3_create_screen () from /run/opengl-driver/lib/libGLX_mesa.so.0
#17 0x00007ffff45b0fa9 in __glXInitialize () from /run/opengl-driver/lib/libGLX_mesa.so.0
#18 0x00007ffff45acb84 in GetGLXPrivScreenConfig () from /run/opengl-driver/lib/libGLX_mesa.so.0
#19 0x00007ffff45ad0fe in glXQueryExtensionsString () from /run/opengl-driver/lib/libGLX_mesa.so.0
#20 0x00007ffff7eaee6e in fgPlatformInitialize () from /nix/store/dwkgb62gdlwx6pyka0yr40q6lwvxf624-freeglut-3.2.1/lib/libglut.so.3
#21 0x00007ffff7ea500c in glutInit () from /nix/store/dwkgb62gdlwx6pyka0yr40q6lwvxf624-freeglut-3.2.1/lib/libglut.so.3
#22 0x0000000000401052 in main (argc=<optimized out>, argv=<optimized out>) at glut.c:5

What is the LLVM embedded in liboclgrind.so doing there?! I suspect that maybe the radeonsi driver is doing some process inspection to find LLVM, and something cannot handle two LLVMs co-existing in the same process. I have no idea how that would happen, though. Also, this stack trace is different to what I get with ROCm. But this may ultimately be a Mesa bug, not a ROCm one.

[athas]

It seems to work if I compile Mesa with LLVM 8 rather than LLVM 9.

[athas]

Seems fixed by #35, but it might also be a change in Mesa for all I know.