Fix PR22634 - std::allocator doesn't respect over-aligned types.

This patch fixes std::allocator, and more specifically, all users
of __libcpp_allocate and __libcpp_deallocate, to support over-aligned
types.

__libcpp_allocate/deallocate now take an alignment parameter, and when
the specified alignment is greater than that supported by malloc/new,
the aligned version of operator new is called (assuming it's available).

When aligned new isn't available, the old behavior has been kept, and the
alignment parameter is ignored.

This patch depends on recent changes to __builtin_operator_new/delete which
allow them to be used to call any regular new/delete operator. By using
__builtin_operator_new/delete when possible, the new/delete erasure optimization
is maintained.

llvm-svn: 328180

1 files changed, 7 insertions, 30 deletions

diff --git a/libcxx/include/memory b/libcxx/include/memory
index ea52ba2cb64..021bd136af4 100644
--- a/libcxx/include/memory
+++ b/libcxx/include/memory
@@ -1796,10 +1796,10 @@ public:
         if (__n > max_size())
             __throw_length_error("allocator<T>::allocate(size_t n)"
                                  " 'n' exceeds maximum supported size");
-        return static_cast<pointer>(_VSTD::__allocate(__n * sizeof(_Tp)));
+        return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), __alignof(_Tp)));
         }
     _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
-        {_VSTD::__libcpp_deallocate((void*)__p);}
+        {_VSTD::__libcpp_deallocate((void*)__p, __alignof(_Tp));}
     _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
         {return size_type(~0) / sizeof(_Tp);}
 #if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
@@ -1897,10 +1897,10 @@ public:
         if (__n > max_size())
             __throw_length_error("allocator<const T>::allocate(size_t n)"
                                  " 'n' exceeds maximum supported size");
-        return static_cast<pointer>(_VSTD::__allocate(__n * sizeof(_Tp)));
+        return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), __alignof(_Tp)));
     }
     _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) _NOEXCEPT
-        {_VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p));}
+        {_VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __alignof(_Tp));}
     _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT
         {return size_type(~0) / sizeof(_Tp);}
 #if !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) && !defined(_LIBCPP_HAS_NO_VARIADICS)
@@ -2016,12 +2016,7 @@ get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
     while (__n > 0)
     {
 #if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
-#if defined(__STDCPP_DEFAULT_NEW_ALIGNMENT__)
-        if (std::alignment_of<_Tp>::value > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
-#else
-        if (std::alignment_of<_Tp>::value >
-            std::alignment_of<std::max_align_t>::value)
-#endif
+    if (__is_overaligned_for_new(__alignof(_Tp)))
         {
             std::align_val_t __al =
                 std::align_val_t(std::alignment_of<_Tp>::value);
@@ -2032,12 +2027,7 @@ get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
                 __n * sizeof(_Tp), nothrow));
         }
 #else
-#if defined(__STDCPP_DEFAULT_NEW_ALIGNMENT__)
-        if (std::alignment_of<_Tp>::value > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
-#else
-        if (std::alignment_of<_Tp>::value >
-            std::alignment_of<std::max_align_t>::value)
-#endif
+    if (__is_overaligned_for_new(__alignof(_Tp)))
         {
             // Since aligned operator new is unavailable, return an empty
             // buffer rather than one with invalid alignment.
@@ -2061,20 +2051,7 @@ template <class _Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 void return_temporary_buffer(_Tp* __p) _NOEXCEPT
 {
-#if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
-#if defined(__STDCPP_DEFAULT_NEW_ALIGNMENT__)
-    if (std::alignment_of<_Tp>::value > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
-#else
-    if (std::alignment_of<_Tp>::value >
-        std::alignment_of<std::max_align_t>::value)
-#endif
-    {
-        std::align_val_t __al = std::align_val_t(std::alignment_of<_Tp>::value);
-        ::operator delete(__p, __al);
-        return;
-    }
-#endif
-    ::operator delete(__p);
+  _VSTD::__libcpp_deallocate((void*)__p, __alignof(_Tp));
 }
 
 #if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR)