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QTypeInfo: add detection for Clang's __is_trivially_relocatable

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Types marked with [[clang::trivial_abi]] are considered to be trivially
relocatable for Clang. This is ABI compatible, since in Qt 6 we can
change the value of QTypeInfo::IsRelocatable "after the fact" -- it
simply means that code that doesn't get recompiled is pessimized.

Change-Id: I32e52bfb212c7919b2ebcf7832ede4404358330f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Giuseppe D'Angelo 2024-03-21 10:48:05 +01:00
parent b20da0ba28
commit f4bac3ca17
2 changed files with 21 additions and 1 deletions
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8
src/corelib/global/qtypeinfo.h
View File

@ -23,7 +23,13 @@ class QDebug;
namespace QtPrivate {
template <typename T>
inline constexpr bool qIsRelocatable = std::is_trivially_copyable_v<T> && std::is_trivially_destructible_v<T>;
inline constexpr bool qIsRelocatable = (std::is_trivially_copyable_v<T> && std::is_trivially_destructible_v<T>)
#if defined(__has_builtin)
#if __has_builtin(__is_trivially_relocatable)
|| __is_trivially_relocatable(T)
#endif
#endif
;
// Denotes types that are trivially default constructible, and for which
// value-initialization can be achieved by filling their storage with 0 bits.

14
tests/auto/corelib/global/qglobal/tst_qglobal.cpp
View File

@ -930,6 +930,20 @@ struct Trivial1
static_assert(!QTypeInfo<Trivial1>::isComplex);
static_assert(QTypeInfo<Trivial1>::isRelocatable);
#if defined(__has_builtin)
#if __has_builtin(__is_trivially_relocatable) && __has_attribute(trivial_abi)
struct [[clang::trivial_abi]] TrivialAbi1
{
~TrivialAbi1();
TrivialAbi1(TrivialAbi1 &&);
};
static_assert(__has_builtin(__is_trivially_relocatable));
static_assert(__is_trivially_relocatable(TrivialAbi1));
static_assert(QTypeInfo<TrivialAbi1>::isComplex);
static_assert(QTypeInfo<TrivialAbi1>::isRelocatable);
#endif
#endif
QT_END_NAMESPACE
QTEST_APPLESS_MAIN(tst_QGlobal)