libcxxabi/test/test_exception_address_alignment.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: libcxxabi-no-exceptions
  10 // UNSUPPORTED: c++98, c++03
  11
  12 // The system unwind.h on OS X provides an incorrectly aligned _Unwind_Exception
  13 // type. That causes these tests to fail. This XFAIL is my best attempt at
  14 // working around this failure.
  15 // XFAIL: darwin && libcxxabi-has-system-unwinder
  16
  17 // Test that the address of the exception object is properly aligned as required
  18 // by the relevant ABI
  19
  20 #include <cstdint>
  21 #include <cassert>
  22 #include <__cxxabi_config.h>
  23
  24 #include <unwind.h>
  25
  26 struct __attribute__((aligned)) AlignedType {};
  27
  28 // EHABI  : 8-byte aligned
  29 // Itanium: Largest supported alignment for the system
  30 #if defined(_LIBCXXABI_ARM_EHABI)
  31 #  define EXPECTED_ALIGNMENT 8
  32 #else
  33 #  define EXPECTED_ALIGNMENT alignof(AlignedType)
  34 #endif
  35
  36 static_assert(alignof(_Unwind_Exception) == EXPECTED_ALIGNMENT,
  37   "_Unwind_Exception is incorrectly aligned. This test is expected to fail");
  38
  39 struct MinAligned {  };
  40 static_assert(alignof(MinAligned) == 1 && sizeof(MinAligned) == 1, "");
  41
  42 int main() {
  43   for (int i=0; i < 10; ++i) {
  44     try {
  45       throw MinAligned{};
  46     } catch (MinAligned const& ref) {
  47       assert(reinterpret_cast<uintptr_t>(&ref) % EXPECTED_ALIGNMENT == 0);
  48     }
  49   }
  50 }