[clang] [llvm] [HLSL] implement elementwise firstbithigh hlsl builtin (PR #111082)

[Farzon Lotfi via cfe-commits]

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@@ -18631,6 +18631,14 @@ static Intrinsic::ID getDotProductIntrinsic(CGHLSLRuntime &RT, QualType QT) {
   return RT.getUDotIntrinsic();
 }
 
+Intrinsic::ID getFirstBitHighIntrinsic(CGHLSLRuntime &RT, QualType QT) {
+  if (QT->hasSignedIntegerRepresentation()) {
+    return RT.getFirstBitSHighIntrinsic();
+  }
+
----------------
farzonl wrote:

```suggestion

  assert(QT->hasUnsignedIntegerRepresentation());
```

https://github.com/llvm/llvm-project/pull/111082