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

[Farzon Lotfi via cfe-commits]

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@@ -1874,6 +1874,26 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
       return true;
     break;
   }
+  case Builtin::BI__builtin_hlsl_elementwise_firstbithigh: {
+    if (SemaRef.PrepareBuiltinElementwiseMathOneArgCall(TheCall))
+      return true;
+
+    const Expr *Arg = TheCall->getArg(0);
+    QualType ArgTy = Arg->getType();
+    QualType EltTy = ArgTy;
+
+    if (auto *VecTy = EltTy->getAs<VectorType>())
+      EltTy = VecTy->getElementType();
+
+    if (!EltTy->isIntegerType() || getASTContext().getTypeSize(EltTy) != 32) {
+      Diag(Arg->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << 1 << /* integer ty */ 6 << ArgTy;
+      return true;
+    }
+
+    TheCall->setType(ArgTy);
----------------
farzonl wrote:

If @bogner is right  this line is a bit more complicated. We will have to construct the call type  as a scalar or vector of the same size as ArgTy but with the element type of int32.

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