[libcxx] [test] XFAIL midpoint.float.pass on AArch64 with compiler-rt

[broadwaylamb]

Summary

This test makes use of subnormal long doubles, which are not implemented in compiler-rt, at least for the aarch64-linux-gnu triple.

[ldionne]

libcxx/utils/libcxx/test/config.py

280

This is already added by Lit IIUC.

283

Not super happy about this for a couple of reasons:

1. It adds more to config.py, which I'm trying to get rid of.
2. There's nothing associated to the use_compiler_rt feature except the Lit feature itself. It's kind of like adding a new feature whose sole purpose is to XFAIL this specific test. Instead, it might make more sense to detect whether subnormal floats are supported?

[broadwaylamb]

libcxx/utils/libcxx/test/config.py

283

2. There's nothing associated to the use_compiler_rt feature except the Lit feature itself. It's kind of like adding a new feature whose sole purpose is to XFAIL this specific test. Instead, it might make more sense to detect whether subnormal floats are supported?

Do you mean like compile and run a test program that makes use of subnormal floats and generate a Lit feature based on whether it succeeds?

[broadwaylamb]

libcxx/utils/libcxx/test/config.py

283

@ldionne could you please explain what you've meant?

[ldionne]

libcxx/utils/libcxx/test/config.py

283

Yes, this is what I meant. I think it would provide more value because it would be detected automatically instead of being set explicitly by users. The test suite is quite complicated to configure today and I'd like to make it simpler. Detecting this automatically would, I think, help us go towards that. WDYT?

[broadwaylamb]

libcxx/utils/libcxx/test/config.py

283

The idea was that when D85032 lands, the XFAILed test will unexpectedly pass, so we don't forget to update that test.

[broadwaylamb]

D85032 has landed, this patch is not needed anymore.

libcxx/test/lit.site.cfg.in

 config.generate_coverage        = @LIBCXX_GENERATE_COVERAGE@
 config.target_info              = "@LIBCXX_TARGET_INFO@"
 config.test_linker_flags        = "@LIBCXX_TEST_LINKER_FLAGS@"
 config.test_compiler_flags      = "@LIBCXX_TEST_COMPILER_FLAGS@"
 
 config.executor                 = "@LIBCXX_EXECUTOR@"
 config.llvm_unwinder            = @LIBCXXABI_USE_LLVM_UNWINDER@
 config.builtins_library         = "@LIBCXX_BUILTINS_LIBRARY@"
+config.use_compiler_rt          = "@LIBCXX_USE_COMPILER_RT@"
 config.has_libatomic            = @LIBCXX_HAS_ATOMIC_LIB@
 config.debug_build              = @LIBCXX_DEBUG_BUILD@
 config.libcxxabi_shared         = @LIBCXX_LINK_TESTS_WITH_SHARED_LIBCXXABI@
 config.cxx_ext_threads          = @LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY@
 config.pstl_src_root            = "@ParallelSTL_SOURCE_DIR@" if @LIBCXX_ENABLE_PARALLEL_ALGORITHMS@ else None
 config.pstl_obj_root            = "@ParallelSTL_BINARY_DIR@" if @LIBCXX_ENABLE_PARALLEL_ALGORITHMS@ else None
 config.libcxx_gdb               = "@LIBCXX_GDB@"
 

libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // UNSUPPORTED: c++03, c++11, c++14, c++17
+//
+// subnormal floats are not implemented in compiler-rt builtins for AArch64.
+// XFAIL: aarch64-linux-gnu && use_compiler_rt
+//
 // <numeric>
 
 // template <class _Float>
 // _Tp midpoint(_Float __a, _Float __b) noexcept
 //
 
 #include <numeric>
 #include <cassert>

libcxx/utils/libcxx/test/config.py

def configure_features(self):
                 # and regressions. Note: New failures should not be suppressed
                 # using this feature. (Also see llvm.org/PR32730)
                 self.config.available_features.add('LIBCXX-WINDOWS-FIXME')
 
         libcxx_gdb = self.get_lit_conf('libcxx_gdb')
         if libcxx_gdb and 'NOTFOUND' not in libcxx_gdb:
             self.config.available_features.add('libcxx_gdb')
             self.cxx.libcxx_gdb = libcxx_gdb
         
+        if self.config.target_triple:
+            self.config.available_features.add(self.config.target_triple)
+
+        if self.get_lit_conf('use_compiler_rt'):
+            self.config.available_features.add('use_compiler_rt')
+
     def configure_compile_flags(self):
         self.configure_default_compile_flags()
         # Configure extra flags
         compile_flags_str = self.get_lit_conf('compile_flags', '')
         self.cxx.compile_flags += shlex.split(compile_flags_str)
         if self.target_info.is_windows():
             # FIXME: Can we remove this?
             self.cxx.compile_flags += ['-D_CRT_SECURE_NO_WARNINGS']