Abort trap:6 JTR 1.8 jumbo OS X 10.10.5

Hey guys, getting this error on my 2014 MBP with discrete GPU. it happens when i try to use my GPUs only with the --devices=1,2 flag, whenever I use my CPU it works flawlessly (but leaves me waiting for super-slow CPU threads to finish) .

[Apple:27025] *** Process received signal ***
[Apple:27025] Signal: Abort trap: 6 (6)
[Apple:27025] Signal code:  (0)
[Apple:27025] [ 0] 0   libsystem_platform.dylib            0x00007fff918c4f1a _sigtramp + 26
[Apple:27025] [ 1] 0   libsystem_pthread.dylib             0x00007fff9a11ac70 __mtx_droplock + 462
[Apple:27025] [ 2] 0   libsystem_c.dylib                   0x00007fff9089c9b3 abort + 129
[Apple:27025] [ 3] 0   libGPUSupportMercury.dylib          0x00007fff91fdeb81 gpumCreateComputeContext + 0
[Apple:27025] [ 4] 0   AppleIntelHD5000GraphicsGLDriver    0x0000000106db449f gpusKillClient + 9
[Apple:27025] [ 5] 0   libGPUSupportMercury.dylib          0x00007fff91fdf538 gpusQueueSubmitDataBuffers + 170
[Apple:27025] [ 6] 0   AppleIntelHD5000GraphicsGLDriver    0x0000000106e09909 _ZN20IntelCLCommandBuffer6getNewEP11GLDQueueRec + 33
[Apple:27025] [ 7] 0   AppleIntelHD5000GraphicsGLDriver    0x0000000106e07817 _Z21intelSubmitCLCommandsP11GLDQueueRecj + 65
[Apple:27025] [ 8] 0   AppleIntelHD5000GraphicsGLDriver    0x0000000106e1d799 _ZN10CHAL_INTEL11ChalContext9ChalFlushEv + 83
[Apple:27025] [ 9] 0   AppleIntelHD5000GraphicsGLDriver    0x0000000106e09b85 gldFinishQueue + 43
[Apple:27025] [10] 0   OpenCL                              0x00007fff955637f0 OpenCL + 6128
[Apple:27025] [11] 0   OpenCL                              0x00007fff95563cba OpenCL + 7354
[Apple:27025] [12] 0   OpenCL                              0x00007fff95581fc4 clSetEventCallback + 6547
[Apple:27025] [13] 0   OpenCL                              0x00007fff9558563b clFinish + 747
[Apple:27025] [14] 0   libdispatch.dylib                   0x00007fff8eae7e73 _dispatch_client_callout + 8
[Apple:27025] [15] 0   libdispatch.dylib                   0x00007fff8eaf760b _dispatch_barrier_sync_f_slow + 757
[Apple:27025] [16] 0   OpenCL                              0x00007fff955854bf clFinish + 367
[Apple:27025] [17] 0   OpenCL                              0x00007fff9558106b clSetEventCallback + 2618
[Apple:27025] [18] 0   OpenCL                              0x00007fff955761c1 clEnqueueReadBuffer + 813
[Apple:27025] [19] 0   john                                0x00000001032fb8b8 crypt_all + 824
[Apple:27025] *** End of error message ***
Abort trap: 6

Start by reproducing the crash on OS X 10.10.5 with GPU-only --devices=1,2, then trace the crypt_all entry point through the OpenCL calls shown in the stack trace. Done means identifying the GPU-specific failure and verifying that the affected workload no longer aborts while CPU-only operation remains intact.