Merge branch 'integ-buff' of github.com:mateuszpn/llvm into integ-buff

Author: mateuszpn

unified-runtime/source/adapters/level_zero/v2/memory.cpp

@@ -121,7 +121,7 @@ ur_integrated_buffer_handle_t::ur_integrated_buffer_handle_t(
 
 ur_integrated_buffer_handle_t::~ur_integrated_buffer_handle_t() {
   if (writeBackPtr) {
-    std::memcpy(writeBackPtr, this->ptr.get(), size);
+    std::memcpy(writeBackPtr, ptr.get(), size);
   }
 }
 
@@ -618,6 +618,12 @@ ur_result_t urMemBufferCreate(ur_context_handle_t hContext,
   void *hostPtr = pProperties ? pProperties->pHost : nullptr;
   auto accessMode = ur_mem_buffer_t::getDeviceAccessMode(flags);
 
+  // For integrated devices, use zero-copy host buffers. The integrated buffer
+  // constructor will handle all cases:
+  // 1. No host pointer - allocate USM host memory
+  // 2. Host pointer is already USM - use directly
+  // 3. Host pointer can be imported - import it
+  // 4. Otherwise - allocate USM and copy-back on destruction
   if (useHostBuffer(hContext)) {
     *phBuffer = ur_mem_handle_t_::create<ur_integrated_buffer_handle_t>(
         hContext, hostPtr, size, accessMode);