Remove llvm::is_trivially_copyable (NFC)

[kazu]

Summary

This patch removes llvm::is_trivially_copyable as it seems to be dead.
Once I remove it, HAVE_STD_IS_TRIVIALLY_COPYABLE has no users, so this
patch removes the macro also.

The comment on llvm::is_trivially_copyable mentions GCC 4.9, but note
that we now require GCC 7.1 or higher.

llvm/cmake/config-ix.cmake

 else()
   unset(HAVE_FFI_FFI_H CACHE)
   unset(HAVE_FFI_H CACHE)
   unset(HAVE_FFI_CALL CACHE)
 endif()
 
 check_symbol_exists(proc_pid_rusage "libproc.h" HAVE_PROC_PID_RUSAGE)
 
-# Whether we can use std::is_trivially_copyable to verify llvm::is_trivially_copyable.
-CHECK_CXX_SOURCE_COMPILES("
-#include <type_traits>
-struct T { int val; };
-static_assert(std::is_trivially_copyable<T>::value, \"ok\");
-int main() { return 0;}
-" HAVE_STD_IS_TRIVIALLY_COPYABLE)
-
-
 # Define LLVM_HAS_ATOMICS if gcc or MSVC atomic builtins are supported.
 include(CheckAtomic)
 
 if( LLVM_ENABLE_PIC )
   set(ENABLE_PIC 1)
 else()
   set(ENABLE_PIC 0)
   check_cxx_compiler_flag("-fno-pie" SUPPORTS_NO_PIE_FLAG)

llvm/include/llvm/ADT/PointerIntPair.h

bool operator<=(const PointerIntPair &RHS) const {
     return Value <= RHS.Value;
   }
 
   bool operator>=(const PointerIntPair &RHS) const {
     return Value >= RHS.Value;
   }
 };
 
-// Specialize is_trivially_copyable to avoid limitation of llvm::is_trivially_copyable
-// when compiled with gcc 4.9.
-template <typename PointerTy, unsigned IntBits, typename IntType,
-          typename PtrTraits,
-          typename Info>
-struct is_trivially_copyable<PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>> : std::true_type {
-#ifdef HAVE_STD_IS_TRIVIALLY_COPYABLE
-  static_assert(std::is_trivially_copyable<PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>>::value,
-                "inconsistent behavior between llvm:: and std:: implementation of is_trivially_copyable");
-#endif
-};
-
-
 template <typename PointerT, unsigned IntBits, typename PtrTraits>
 struct PointerIntPairInfo {
   static_assert(PtrTraits::NumLowBitsAvailable <
                     std::numeric_limits<uintptr_t>::digits,
                 "cannot use a pointer type that has all bits free");
   static_assert(IntBits <= PtrTraits::NumLowBitsAvailable,
                 "PointerIntPair with integer size too large for pointer");
   enum MaskAndShiftConstants : uintptr_t {

llvm/include/llvm/Config/config.h.cmake

 #cmakedefine PACKAGE_STRING "${PACKAGE_STRING}"
 
 /* Define to the version of this package. */
 #cmakedefine PACKAGE_VERSION "${PACKAGE_VERSION}"
 
 /* Define to the vendor of this package. */
 #cmakedefine PACKAGE_VENDOR "${PACKAGE_VENDOR}"
 
-/* Define if std::is_trivially_copyable is supported */
-#cmakedefine HAVE_STD_IS_TRIVIALLY_COPYABLE ${HAVE_STD_IS_TRIVIALLY_COPYABLE}
-
 /* Define to a function implementing stricmp */
 #cmakedefine stricmp ${stricmp}
 
 /* Define to a function implementing strdup */
 #cmakedefine strdup ${strdup}
 
 /* Whether GlobalISel rule coverage is being collected */
 #cmakedefine01 LLVM_GISEL_COV_ENABLED

llvm/include/llvm/Support/type_traits.h

 template <typename T>
 struct is_move_assignable {
   template<class F>
     static auto get(F*) -> decltype(std::declval<F &>() = std::declval<F &&>(), std::true_type{});
     static std::false_type get(...);
     static constexpr bool value = decltype(get((T*)nullptr))::value;
 };
 
-
-// An implementation of `std::is_trivially_copyable` since STL version
-// is not equally supported by all compilers, especially GCC 4.9.
-// Uniform implementation of this trait is important for ABI compatibility
-// as it has an impact on SmallVector's ABI (among others).
-template <typename T>
-class is_trivially_copyable {
-
-  // copy constructors
-  static constexpr bool has_trivial_copy_constructor =
-      std::is_copy_constructible<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_copy_constructor =
-      !std::is_copy_constructible<T>::value;
-
-  // move constructors
-  static constexpr bool has_trivial_move_constructor =
-      std::is_move_constructible<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_move_constructor =
-      !std::is_move_constructible<T>::value;
-
-  // copy assign
-  static constexpr bool has_trivial_copy_assign =
-      is_copy_assignable<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_copy_assign =
-      !is_copy_assignable<T>::value;
-
-  // move assign
-  static constexpr bool has_trivial_move_assign =
-      is_move_assignable<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_move_assign =
-      !is_move_assignable<T>::value;
-
-  // destructor
-  static constexpr bool has_trivial_destructor =
-      std::is_destructible<detail::trivial_helper<T>>::value;
-
-  public:
-
-  static constexpr bool value =
-      has_trivial_destructor &&
-      (has_deleted_move_assign || has_trivial_move_assign) &&
-      (has_deleted_move_constructor || has_trivial_move_constructor) &&
-      (has_deleted_copy_assign || has_trivial_copy_assign) &&
-      (has_deleted_copy_constructor || has_trivial_copy_constructor);
-
-#ifdef HAVE_STD_IS_TRIVIALLY_COPYABLE
-  static_assert(value == std::is_trivially_copyable<T>::value,
-                "inconsistent behavior between llvm:: and std:: implementation of is_trivially_copyable");
-#endif
-};
-template <typename T>
-class is_trivially_copyable<T*> : public std::true_type {
-};
-
-
 } // end namespace llvm
 
 #endif // LLVM_SUPPORT_TYPE_TRAITS_H

llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn

values = [
     "HAVE_FENV_H=1",
     "HAVE_FFI_CALL=",
     "HAVE_FFI_FFI_H=",
     "HAVE_FFI_H=",
     "HAVE_LIBPFM=",
     "HAVE_LIBPSAPI=",
     "HAVE_MALLCTL=",
     "HAVE_SIGNAL_H=1",
-    "HAVE_STD_IS_TRIVIALLY_COPYABLE=1",
     "HAVE_STRERROR=1",
     "HAVE_SYS_STAT_H=1",
     "HAVE_SYS_TYPES_H=1",
     "HAVE_VALGRIND_VALGRIND_H=",
     "HAVE__ALLOCA=",
     "HAVE___ALLOCA=",
     "HAVE___ASHLDI3=",
     "HAVE___ASHRDI3=",

utils/bazel/llvm-project-overlay/llvm/include/llvm/Config/config.h

 #define PACKAGE_STRING PACKAGE_NAME " " LLVM_VERSION_STRING
 
 /* Define to the version of this package. */
 #define PACKAGE_VERSION LLVM_VERSION_STRING
 
 /* Define to the vendor of this package. */
 /* #undef PACKAGE_VENDOR */
 
-/* Define if std::is_trivially_copyable is supported */
-#define HAVE_STD_IS_TRIVIALLY_COPYABLE 1
-
 /* Define to a function implementing stricmp */
 /* stricmp defined conditionally below. */
 
 /* Define to a function implementing strdup */
 /* strdup defined conditionally below. */
 
 /* Whether GlobalISel rule coverage is being collected */
 #define LLVM_GISEL_COV_ENABLED 0

utils/bazel/llvm_configs/config.h.cmake

 #cmakedefine PACKAGE_STRING "${PACKAGE_STRING}"
 
 /* Define to the version of this package. */
 #cmakedefine PACKAGE_VERSION "${PACKAGE_VERSION}"
 
 /* Define to the vendor of this package. */
 #cmakedefine PACKAGE_VENDOR "${PACKAGE_VENDOR}"
 
-/* Define if std::is_trivially_copyable is supported */
-#cmakedefine HAVE_STD_IS_TRIVIALLY_COPYABLE ${HAVE_STD_IS_TRIVIALLY_COPYABLE}
-
 /* Define to a function implementing stricmp */
 #cmakedefine stricmp ${stricmp}
 
 /* Define to a function implementing strdup */
 #cmakedefine strdup ${strdup}
 
 /* Whether GlobalISel rule coverage is being collected */
 #cmakedefine01 LLVM_GISEL_COV_ENABLED