rocm-systems/docs/markdown/hip_bugs.md

HIP Bugs

• Errors related to undefined reference to `hcLaunchKernel*__grid_launch_parm
• Application hangs after a hipLaunchKernel call

Errors related to undefined reference to `hcLaunchKernel*__grid_launch_parm

Some common code practices may lead to hipcc generating a error with the form : undefined reference to `_hcLaunchKernel__ZN15vecAddNamespace6vecAddIidEEv16grid_launch_parmPT0_S3_S3_T

To workaround, try:

• Avoid calling hcLaunchKernel from a function with the host attribute host MyFunc(…) { hipLaunchKernel(myKernel, …)
• Avoid use of static with kernel definition: static global MyKernel
• Avoid defining kernels in anonymous namespace namespace { global MyKernel …
• Avoid calling member functions

What if I see application hangs after a hipLaunchKernel call?

If hipLaunchKernel takes parameters that request explicitly memcpy, then it will cause application hang. Reason is that the hipLaunchKernel macro locks the stream.
If kernel paramters are actually function calls which invoke other hip apis (i.e. memcpy) to the same stream, then deadlock occurs.

To workaround, try: Move the function calls so they occur outside the hipLaunchKernel macro, store results in temps, then use the tems inside the kernel.

// Example pseudo code causing system hang:
// "bottom[0]->gpu_data()" calls hipMemcpy() implicitly and using the same stream, cause deadlock condition.
hipLaunchKernel(HIP_KERNEL_NAME(LRNComputeDiff),dim3(CAFFE_GET_BLOCKS(n_threads)), dim3(CAFFE_HIP_NUM_THREADS), 0, 0, n_threads,
       bottom[0]->gpu_data());
       
// Move "gpu_data()" ouside of hipLaunchKernel to avoid hang. 
auto bot_gpu_data = bottom[0]->gpu_data();
hipLaunchKernel( LRNComputeDiff, dim3(CAFFE_GET_BLOCKS(n_threads)), dim3(CAFFE_HIP_NUM_THREADS), 0, 0, n_threads, 
       bot_gpu_data);