[clang] [Clang][OpenCL] Add support for the cl_intel_subgroup_buffer_prefetch (PR #170532)

[Mészáros Gergely via cfe-commits]

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@@ -17839,6 +17862,13 @@ void        __ovld __conv intel_sub_group_block_write_ul(  __global ulong* p, ul
 void        __ovld __conv intel_sub_group_block_write_ul2( __global ulong* p, ulong2 data );
 void        __ovld __conv intel_sub_group_block_write_ul4( __global ulong* p, ulong4 data );
 void        __ovld __conv intel_sub_group_block_write_ul8( __global ulong* p, ulong8 data);
+
+#if defined(cl_intel_subgroup_buffer_prefetch)
+void __ovld __conv intel_sub_group_block_prefetch_ul(const __global ulong *p);
+void __ovld __conv intel_sub_group_block_prefetch_ul2(const __global ulong *p);
+void __ovld __conv intel_sub_group_block_prefetch_ul4(const __global ulong *p);
+void __ovld __conv intel_sub_group_block_prefetch_ul8(const __global ulong *p);
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Maetveis wrote:

```suggestion
void        __ovld __conv intel_sub_group_block_prefetch_ul(const __global ulong *p);
void        __ovld __conv intel_sub_group_block_prefetch_ul2(const __global ulong *p);
void        __ovld __conv intel_sub_group_block_prefetch_ul4(const __global ulong *p);
void        __ovld __conv intel_sub_group_block_prefetch_ul8(const __global ulong *p);
```

https://github.com/llvm/llvm-project/pull/170532