[clang] [CIR] Upstream ClearCacheOp support for __builtin___clear_cache (PR #178260)

[Andy Kaylor via cfe-commits]

================
@@ -5254,6 +5111,26 @@ def CIR_PrefetchOp : CIR_Op<"prefetch"> {
     }];
 }
 
+//===----------------------------------------------------------------------===//
+// ClearCacheOp
+//===----------------------------------------------------------------------===//
+
+def CIR_ClearCacheOp : CIR_Op<"clear_cache", [
+  AllTypesMatch<["begin", "end"]>
+]> {
+  let summary = "clear cache operation";
----------------
andykaylor wrote:

```suggestion
  let summary = "Clear the processor’s instruction cache if required.";
```

https://github.com/llvm/llvm-project/pull/178260