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Fix llvm::is_trivially_copyable portability issues

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llvm::is_trivially_copyable portability is verified at compile time using
std::is_trivially_copyable as the reference implementation.

Unfortunately, the latter is not available on all platforms, so introduce
a proper configure check to detect if it is available on the target platform.

In a similar manner, std::is_copy_assignable is not fully supported for gcc4.9.
Provide a portable (?) implementation instead.

Differential Revision: https://reviews.llvm.org/D57018

llvm-svn: 351820
This commit is contained in:
Serge Guelton 2019-01-22 13:48:55 +00:00
parent af41a20065
commit 1e000b2c69
4 changed files with 55 additions and 6 deletions
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9
cmake/config-ix.cmake
View File

@ -325,6 +325,15 @@ else()
unset(HAVE_FFI_CALL CACHE)
endif( LLVM_ENABLE_FFI )
# 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)

14
include/llvm/ADT/PointerIntPair.h
View File

@ -14,6 +14,7 @@
#define LLVM_ADT_POINTERINTPAIR_H
#include "llvm/Support/PointerLikeTypeTraits.h"
#include "llvm/Support/type_traits.h"
#include <cassert>
#include <cstdint>
#include <limits>
@ -125,6 +126,19 @@ public:
}
};
// 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 <

3
include/llvm/Config/config.h.cmake
View File

@ -338,6 +338,9 @@
/* Define as the return type of signal handlers (`int' or `void'). */
#cmakedefine RETSIGTYPE ${RETSIGTYPE}
/* 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}

35
include/llvm/Support/type_traits.h
View File

@ -95,6 +95,7 @@ template<class T>
union trivial_helper {
T t;
};
} // end namespace detail
/// An implementation of `std::is_trivially_copy_constructible` since we have
@ -119,6 +120,24 @@ struct is_trivially_move_constructible<T &> : std::true_type {};
template <typename T>
struct is_trivially_move_constructible<T &&> : std::true_type {};
template <typename T>
struct is_copy_assignable {
template<class F>
static auto get(F*) -> decltype(std::declval<T &>() = std::declval<const T &>(), std::true_type{});
static std::false_type get(...);
static constexpr bool value = decltype(get((T*)nullptr))::value;
};
template <typename T>
struct is_move_assignable {
template<class F>
static auto get(F*) -> decltype(std::declval<T &>() = std::declval<T &&>(), 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
@ -140,15 +159,15 @@ class is_trivially_copyable {
// copy assign
static constexpr bool has_trivial_copy_assign =
std::is_copy_assignable<detail::trivial_helper<T>>::value;
is_copy_assignable<detail::trivial_helper<T>>::value;
static constexpr bool has_deleted_copy_assign =
!std::is_copy_assignable<T>::value;
!is_copy_assignable<T>::value;
// move assign
static constexpr bool has_trivial_move_assign =
std::is_move_assignable<detail::trivial_helper<T>>::value;
is_move_assignable<detail::trivial_helper<T>>::value;
static constexpr bool has_deleted_move_assign =
!std::is_move_assignable<T>::value;
!is_move_assignable<T>::value;
// destructor
static constexpr bool has_trivial_destructor =
@ -163,10 +182,14 @@ class is_trivially_copyable {
(has_deleted_copy_assign || has_trivial_copy_assign) &&
(has_deleted_copy_constructor || has_trivial_copy_constructor);
#if (__has_feature(is_trivially_copyable) || (defined(__GNUC__) && __GNUC__ >= 5))
static_assert(value == std::is_trivially_copyable<T>::value, "inconsistent behavior between llvm:: and std:: implementation of is_trivially_copyable");
#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