Index: flang/lib/Evaluate/intrinsics-library.cpp
===================================================================
--- flang/lib/Evaluate/intrinsics-library.cpp
+++ flang/lib/Evaluate/intrinsics-library.cpp
@@ -330,12 +330,16 @@
   using F = FuncPointer<long double, long double>;
   using FN = FuncPointer<long double, int, long double>;
   static constexpr HostRuntimeFunction table[]{
-      FolderFactory<F, F{::j0l}>::Create("bessel_j0"),
-      FolderFactory<F, F{::j1l}>::Create("bessel_j1"),
-      FolderFactory<FN, FN{::jnl}>::Create("bessel_jn"),
-      FolderFactory<F, F{::y0l}>::Create("bessel_y0"),
-      FolderFactory<F, F{::y1l}>::Create("bessel_y1"),
-      FolderFactory<FN, FN{::ynl}>::Create("bessel_yn"),
+#if defined(__PPC__) && defined(__LONG_DOUBLE_128__) && \
+    !defined(__LONG_DOUBLE_IEEE128__)
+    // double-double, not supported; TODO: use HostTypeExists instead
+    FolderFactory<F, F{::j0l}>::Create("bessel_j0"),
+        FolderFactory<F, F{::j1l}>::Create("bessel_j1"),
+        FolderFactory<FN, FN{::jnl}>::Create("bessel_jn"),
+        FolderFactory<F, F{::y0l}>::Create("bessel_y0"),
+        FolderFactory<F, F{::y1l}>::Create("bessel_y1"),
+        FolderFactory<FN, FN{::ynl}>::Create("bessel_yn"),
+#endif // defined(__PPC__) && ...
   };
   static constexpr HostRuntimeMap map{table};
   static_assert(map.Verify(), "map must be sorted");