Author: Richard Smith Date: 2020-03-23T16:31:10-07:00 New Revision: 5bd06118c2a798f1f87b9251953bae8a27f21e5f
URL: https://github.com/llvm/llvm-project/commit/5bd06118c2a798f1f87b9251953bae8a27f21e5f DIFF: https://github.com/llvm/llvm-project/commit/5bd06118c2a798f1f87b9251953bae8a27f21e5f.diff LOG: Update documentation for __builtin_operator_new and __builtin_operator_delete to match r328134. Added: Modified: clang/docs/LanguageExtensions.rst Removed: ################################################################################ diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index aee0b82880ba..f9511dc1a02f 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -2129,21 +2129,32 @@ object that overloads ``operator&``. ``__builtin_operator_new`` and ``__builtin_operator_delete`` ------------------------------------------------------------ -``__builtin_operator_new`` allocates memory just like a non-placement non-class -*new-expression*. This is exactly like directly calling the normal -non-placement ``::operator new``, except that it allows certain optimizations +A call to ``__builtin_operator_new(args)`` is exactly the same as a call to +``::operator new(args)``, except that it allows certain optimizations that the C++ standard does not permit for a direct function call to ``::operator new`` (in particular, removing ``new`` / ``delete`` pairs and -merging allocations). +merging allocations), and that the call is required to resolve to a +`replaceable global allocation function +<https://en.cppreference.com/w/cpp/memory/new/operator_new>`_. -Likewise, ``__builtin_operator_delete`` deallocates memory just like a -non-class *delete-expression*, and is exactly like directly calling the normal -``::operator delete``, except that it permits optimizations. Only the unsized -form of ``__builtin_operator_delete`` is currently available. +Likewise, ``__builtin_operator_delete`` is exactly the same as a call to +``::operator delete(args)``, except that it permits optimizations +and that the call is required to resolve to a +`replaceable global deallocation function +<https://en.cppreference.com/w/cpp/memory/new/operator_delete>`_. These builtins are intended for use in the implementation of ``std::allocator`` and other similar allocation libraries, and are only available in C++. +Query for this feature with ``__has_builtin(__builtin_operator_new)`` or +``__has_builtin(__builtin_operator_delete)``: + + * If the value is at least ``201802L``, the builtins behave as described above. + + * If the value is non-zero, the builtins may not support calling arbitrary + replaceable global (de)allocation functions, but do support calling at least + ``::operator new(size_t)`` and ``::operator delete(void*)``. + ``__builtin_preserve_access_index`` ----------------------------------- _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
