[flang] Get ppc64le build bot back up

[klausler]

Summary

A recent change assumed that the native C++ "long double" maps to
a Fortran data type; but this turns out to not be true for ppc64le,
which uses "double-double" for "long double".

This is a quick patch to get the ppc64le flang build bot back up.
A better fix that either uses HostTypeExists<> or replaces "long double"
with "ieee128_t" (or some other solution) is expected to follow soon.

[klausler]

Remove irrelevant changes; the patch should be a simple #if/#endif exclusion on _ARCH_PPC.

[kiranchandramohan]

The CI is complaining about a clang-format issue in flang/lib/Evaluate/intrinsics-library.cpp

[jeanPerier]

I am surprised because the dispatching uses host::FortranType<HostT> (at [1]) to avoid making assumptions regarding what the host floating points are. So I would have expected this code to automatically map long double to REAL(16) on ppc64le, but obviously, there is a bug/issue somewhere. Thanks for the fix.

[1]: https://github.com/llvm/llvm-project/blob/e356027016c6365b3d8924f54c33e2c63d931492/flang/lib/Evaluate/intrinsics-library.cpp#L367-L375

[nemanjai]

This can go in as it is. Both Clang and GCC define this macro on PPC. However, it will mean that we don't define these even for compilations with -mabi=ieeelongdouble and -mlong-double-64. If it matters that this works when long double means IEEE 754-R Quad Precision or simply double precision, you could guard it with something like the following

#if defined(__PPC__) && defined(__LONG_DOUBLE_128__) && !defined(__LONG_DOUBLE_IEEE128__)

[klausler]

In D124423#3474604, @nemanjai wrote:

This can go in as it is. Both Clang and GCC define this macro on PPC. However, it will mean that we don't define these even for compilations with -mabi=ieeelongdouble and -mlong-double-64. If it matters that this works when long double means IEEE 754-R Quad Precision or simply double precision, you could guard it with something like the following

#if defined(__PPC__) && defined(__LONG_DOUBLE_128__) && !defined(__LONG_DOUBLE_IEEE128__)

Will update and reformat and try again.

[klausler]

Use more precise #if predicate & reformat to placate CI.

[klausler]

Reverse the #if predicate, and wrap it around the whole function to avoid error from an empty array.

[nemanjai]

LGTM. Thanks for the fix.

[klausler]

The ppc64l. flang build bot is now green.

flang/lib/Evaluate/intrinsics-library.cpp

static constexpr HostRuntimeFunction table[]{
       FolderFactory<F, F{::y0}>::Create("bessel_y0"),
       FolderFactory<F, F{::y1}>::Create("bessel_y1"),
       FolderFactory<FN, FN{::yn}>::Create("bessel_yn"),
   };
   static constexpr HostRuntimeMap map{table};
   static_assert(map.Verify(), "map must be sorted");
 };
 
+#if !defined(__PPC__) || defined(__LONG_DOUBLE_IEEE128__)
+// TODO: use HostTypeExists instead?
 template <>
 struct HostRuntimeLibrary<long double, LibraryVersion::LibmExtensions> {
   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"),
   };
   static constexpr HostRuntimeMap map{table};
   static_assert(map.Verify(), "map must be sorted");
 };
+#endif // !defined(__PPC__) || defined(__LONG_DOUBLE_IEEE128__)
 #endif
 
 /// Define pgmath description
 #if LINK_WITH_LIBPGMATH
 // Only use libpgmath for folding if it is available.
 // First declare all libpgmaths functions
 #define PGMATH_LINKING
 #define PGMATH_DECLARE