[llvm] [libsycl] Implement fill & memset queue API (PR #217933)

[via llvm-commits]

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@@ -560,6 +641,18 @@ class _LIBSYCL_EXPORT queue {
   /// \return an event representing last kernel invocation.
   event getLastEvent();
 
+  /// Submits a fill operation that replicates a pattern into USM accessible
+  /// on the device associated with the queue.
+  ///
+  /// \param Ptr is the pointer to memory to be filled.
+  /// \param Pattern is the pattern to be replicated.
+  /// \param PatternSize is the size of the pattern in bytes.
+  /// \param Count is the number of times the pattern is filled.
+  /// \param DepEvents is a vector of events that represent dependencies for the
+  /// operation.
+  event fillImpl(void *Ptr, const void *Pattern, std::size_t PatternSize,
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Robertkq wrote:

This doesn't match up with existing code and `queue::fillImpl` is mostly a wrapper towards `impl->fill`. I don't see a reason for which this fill needs special treatment

Can you remove this function and move it's code into
```cpp
template <typename T>
  event fill(void *ptr, const T &pattern, std::size_t count,
             const std::vector<event> &depEvents) {
    // here
  }
```
or explain why this needs special treatment? 

https://github.com/llvm/llvm-project/pull/217933