[libc-commits] [libc] [amdgpu][openmp] Avoiding writing to packet header twice (PR #70695)

[Joseph Huber via libc-commits]

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@@ -222,34 +222,36 @@ hsa_status_t launch_kernel(hsa_agent_t dev_agent, hsa_executable_t executable,
   // Set up the packet for exeuction on the device. We currently only launch
   // with one thread on the device, forcing the rest of the wavefront to be
   // masked off.
-  std::memset(packet, 0, sizeof(hsa_kernel_dispatch_packet_t));
-  packet->setup = (1 + (params.num_blocks_y * params.num_threads_y != 1) +
-                   (params.num_blocks_z * params.num_threads_z != 1))
-                  << HSA_KERNEL_DISPATCH_PACKET_SETUP_DIMENSIONS;
+  uint16_t setup = (1 + (params.num_blocks_y * params.num_threads_y != 1) +
+                    (params.num_blocks_z * params.num_threads_z != 1))
+                   << HSA_KERNEL_DISPATCH_PACKET_SETUP_DIMENSIONS;
   packet->workgroup_size_x = params.num_threads_x;
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jhuber6 wrote:

I think we should keep the `memset` but offset it by the first 4 bytes so we don't need to worry about the reserved fields off of the packet.  Unless it's very important that we write to these only once.

https://github.com/llvm/llvm-project/pull/70695