[clang] [llvm] [HLSL] Implement the `smoothstep` intrinsic (PR #132288)

[Farzon Lotfi via llvm-commits]

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@@ -101,6 +101,52 @@ bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
     TheCall->setType(RetTy);
     break;
   }
+  case SPIRV::BI__builtin_spirv_smoothstep: {
+    if (SemaRef.checkArgCount(TheCall, 3))
+      return true;
+
+    // check if the all arguments have floating representation
+    ExprResult A = TheCall->getArg(0);
+    QualType ArgTyA = A.get()->getType();
+    if (!ArgTyA->hasFloatingRepresentation()) {
+      SemaRef.Diag(A.get()->getBeginLoc(),
+                   diag::err_typecheck_convert_incompatible)
----------------
farzonl wrote:

we are in the process of removing out usages of `err_typecheck_convert_incompatible` because it forces an assumption on our part of what the expected type is, in this case `SemaRef.Context.FloatTy`. Look into `err_builtin_invalid_arg_type` instead. It should give us the option to tell the user that this api supports vector floats and and half types.

https://github.com/llvm/llvm-project/pull/132288