[llvm] [Offload] Add `olMemcpyRect` with amdgpu implementation (PR #160321)

[Ross Brunton via llvm-commits]

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@@ -126,6 +126,15 @@ struct KernelLaunchParamsTy {
   /// Ptrs to the Data entries. Only strictly required for the host plugin.
   void **Ptrs = nullptr;
 };
+
+/// Rectangular range for rect memcpies. Should be the same layout as
+/// liboffload's `ol_memcpy_rect_t`.
+struct MemcpyRectTy {
+  void *Base;
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RossBrunton wrote:

Looks like that would make `MemcpyRectTy` non-trivially-copyable, which means it can't be used in bit_cast.

https://github.com/llvm/llvm-project/pull/160321