iOS Crash - s_SkinVertices4Bones_Tangents_NEON_loop

We are seeing a very high number of crashes coming from iOS devices on Unity 5.3.6f1. These appear to be happening in Unity code while doing some mobile mesh optimizations.

I have found a couple of other issues I have included below that appear similar to ours, in which Unity has responded with: "Won't fix: issue was fixed by rebuilding assets for a later version of Unity". The memory workaround is not an option for us. The later version (assuming they mean Unity version) also is not something we can currently do.

For starters, am I correct in assuming that this is a skinned mesh optimization based off the call stack below? Secondly, can anyone clarify exactly what those methods are doing? Is this something that every mesh goes through, only skinned, only while playing animations, etc? This is causing tens of thousands of crashes at this point, and any help would be greatly appreciated.

Crashed: com.apple.main-thread 0 xxxxxxxxxxxxxxxx 0x101872a8c s_SkinVertices4Bones_Tangents_NEON_loop (MeshSkinningNeon64_Loop.inc:355) 1 xxxxxxxxxxxxxxxx 0x10144d5a8 SkinMeshOptimizedMobile(SkinMeshInfo&) (MeshSkinningMobile.h:149) 2 xxxxxxxxxxxxxxxx 0x10144c9b4 DeformSkinnedMesh(SkinMeshInfo&) (MeshSkinning.cpp:73) 3 xxxxxxxxxxxxxxxx 0x10144ca24 DeformSkinnedMeshJob(SkinMeshInfo*) (MeshSkinning.cpp:161) 4 xxxxxxxxxxxxxxxx 0x1013ee1cc JobQueue::Exec(JobInfo*, long long, int) (JobQueue.cpp:356) 5 xxxxxxxxxxxxxxxx 0x1013ee13c JobQueue::Steal(JobGroup*, JobInfo*, long long, int, bool) (JobQueue.cpp:563) 6 xxxxxxxxxxxxxxxx 0x1013eecdc JobQueue::WaitForJobGroup(JobGroupID, bool) (JobQueue.cpp:1367) 7 xxxxxxxxxxxxxxxx 0x1013ed27c CompleteFenceInternal(JobFence&) (Jobs.cpp:27) 8 xxxxxxxxxxxxxxxx 0x101466304 GeometryJobTasks:: PutGeometryJobFence(GfxDevice&, unsigned int) (GeometryJob.cpp:37) 9 xxxxxxxxxxxxxxxx 0x10142f158 SkinnedMeshRenderer::EndCurrentSkinningInstance() (SkinnedMeshRenderer.cpp:1585) 10 xxxxxxxxxxxxxxxx 0x10142f8d0 SkinnedMeshRenderer::Render(int, ChannelAssigns const&) (SkinnedMeshRenderer.cpp:1049) 11 xxxxxxxxxxxxxxxx 0x1013ae498 ForwardShaderRenderLoop:: PerformRendering(JobFence&, ActiveLight const*, ShadowCullData const&, bool, bool, bool, int) (ForwardShaderRenderLoop.cpp:789) 12 xxxxxxxxxxxxxxxx 0x1013af2d8 DoForwardShaderRenderLoop(RenderLoopContext&, dynamic_array&, bool, bool, ActiveLights&, bool, int) (ForwardShaderRenderLoop.cpp:165) 13 xxxxxxxxxxxxxxxx 0x1013b5b50 DoRenderLoop(RenderLoop&, RenderingPath, CullResults&, ShadowMapCache&, bool) (RenderLoopPrivate.cpp:436) 14 xxxxxxxxxxxxxxxx 0x10135ad60 Camera:: DoRender(CullResults&, void ()(Camera&, RenderLoop&, CullResults&), int) (Camera.cpp:1254) 15 xxxxxxxxxxxxxxxx 0x10135c488 Camera::Render(CullResults&, ShaderPassContext&, CameraRenderingParams const, int) (Camera.cpp:1986) 16 xxxxxxxxxxxxxxxx 0x10138d818 RenderManager::RenderCameras(int) (RenderManager.cpp:129) 17 xxxxxxxxxxxxxxxx 0x1014cbbdc PlayerRender(bool) (Player.cpp:1344) 18 xxxxxxxxxxxxxxxx 0x1014cc594 PlayerLoop(bool, bool, IHookEvent*) (Player.cpp:1855) 19 xxxxxxxxxxxxxxxx 0x1017f9570 UnityPlayerLoopImpl(bool) (LibEntryPoint.mm:240) 20 xxxxxxxxxxxxxxxx 0x10004b84c UnityRepaint (UnityAppController+Rendering.mm:234) 21 xxxxxxxxxxxxxxxx 0x10004b68c -[UnityAppController(Rendering) repaintDisplayLink] (UnityAppController+Rendering.mm:49) 22 QuartzCore 0x18344f814 CA:: Display:: DisplayLinkItem::dispatch() + 40 23 QuartzCore 0x18344f6c8 CA:: Display:: DisplayLink::dispatch_items(unsigned long long, unsigned long long, unsigned long long) + 424 24 IOKit 0x180f7a1e8 IODispatchCalloutFromCFMessage + 372 25 CoreFoundation 0x180ca71f8 __CFMachPortPerform + 180 26 CoreFoundation 0x180cbd634 CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION + 56 27 CoreFoundation 0x180cbcd6c __CFRunLoopDoSource1 + 436 28 CoreFoundation 0x180cbaac4 __CFRunLoopRun + 1800 29 CoreFoundation 0x180be9680 CFRunLoopRunSpecific + 384 30 GraphicsServices 0x1820f8088 GSEventRunModal + 180 31 UIKit 0x185a60d90 UIApplicationMain + 204 32 xxxxxxxxxxxxxxxx 0x10004556c main (main.mm:32)

Similar Issues:

https://issuetracker.unity3d.com/issues/crash-in-s-skinvertices4bones-tangents-neon-loop-when-reloading-mesh

https://community.unity.com/t5/iOS-tvOS/Issues-with-VFP-NEON-Mesh-Skinning-Optimizations-on-iOS-5-0/td-p/878510