[DirectX] only allow intrinsics defined in DXIL.td

Fixes #128071
The current behavior lets intrinsics that don't map to a DXILOP
slip through. Nothing catches this until we hit the DXIL validator.
This change fails earlier so we don't encode invalid llvm intrinsics
that can slip through because of clang builtins like
`__builtin_reduce_and`
example:
https://hlsl.godbolt.org/z/13rPj18vn

Author: farzonl

llvm/lib/Target/DirectX/DXILOpLowering.cpp

@@ -770,8 +770,11 @@ class OpLowerer {
         continue;
       Intrinsic::ID ID = F.getIntrinsicID();
       switch (ID) {
-      default:
-        continue;
+      default: {
+        DiagnosticInfoUnsupported Diag(F, "Unknown intrinsic?");
+        M.getContext().diagnose(Diag);
+        break;
+      }
 #define DXIL_OP_INTRINSIC(OpCode, Intrin, ...)                                 \
   case Intrin:                                                                 \
     HasErrors |= replaceFunctionWithOp(                                        \

llvm/test/CodeGen/DirectX/unknown_intrinsic.ll

@@ -0,0 +1,11 @@
+; RUN: not opt -S -scalarizer -dxil-op-lower -mtriple=dxil-pc-shadermodel6.3-library %s 2>&1 | FileCheck %s
+
+; CHECK: error: <unknown>:0:0: in function llvm.vector.reduce.and.v4i32 i32 (<4 x i32>): Unknown intrinsic?
+define i32 @fn_and(<4 x i32> %0) local_unnamed_addr #0 {
+  %2 = tail call i32 @llvm.vector.reduce.and.v4i32(<4 x i32> %0)
+  ret i32 %2
+}
+
+declare i32 @llvm.vector.reduce.and.v4i32(<4 x i32>)
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}