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use __builtin_operator_new for a better compile time support #1275

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use __builtin_operator_new for a better compile time support #1275

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889a47e
use __builtin_operator_new for a better compile time support
SekaiArendelle May 18, 2026
8e184c7
add missing constexpr
SekaiArendelle May 18, 2026
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118 changes: 91 additions & 27 deletions include/fast_io_core_impl/allocation/adapters.h
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Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_new)
return __builtin_operator_new(n);
#else
return ::operator new(n);
#endif
}
else
#endif
Expand Down Expand Up @@ -416,7 +420,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_delete)
__builtin_operator_delete(p);
#else
::operator delete(p);
#endif
}
else
#endif
Expand All @@ -438,7 +446,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_delete)
__builtin_operator_delete(p);
#else
::operator delete(p);
#endif
}
else
#endif
Expand Down Expand Up @@ -478,7 +490,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_new)
return __builtin_operator_new(n);
#else
return ::operator new(n);
#endif
}
else
#endif
Expand All @@ -498,7 +514,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
return ::operator new(n); // this is problematic. No way to clean it up at compile time.
#if __has_builtin(__builtin_operator_new)
return __builtin_operator_new(n);
#else
return ::operator new(n);
#endif // this is problematic. No way to clean it up at compile time.
}
else
#endif
Expand All @@ -520,7 +540,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_new)
return {__builtin_operator_new(n), n};
#else
return {::operator new(n), n};
#endif
}
else
#endif
Expand Down Expand Up @@ -555,7 +579,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_new)
return {__builtin_operator_new(n), n};
#else
return {::operator new(n), n};
#endif
}
else
#endif
Expand Down Expand Up @@ -591,7 +619,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_new)
return {__builtin_operator_new(n), n};
#else
return {::operator new(n), n};
#endif
}
else
#endif
Expand Down Expand Up @@ -623,7 +655,11 @@ class generic_allocator_adapter
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
#if __has_builtin(__builtin_operator_new)
return {__builtin_operator_new(n), n};
#else
return {::operator new(n), n};
#endif
}
else
#endif
Expand Down Expand Up @@ -1141,57 +1177,85 @@ class generic_allocator_adapter

static inline constexpr bool has_deallocate_aligned = (::fast_io::details::has_deallocate_aligned_impl<alloc> ||
::fast_io::details::has_deallocate_impl<alloc>);
static inline void deallocate_aligned(void *p, ::std::size_t alignment) noexcept
static inline constexpr void deallocate_aligned(void *p, ::std::size_t alignment) noexcept
requires(!has_status && has_deallocate_aligned)
{
if constexpr (::fast_io::details::has_deallocate_aligned_impl<alloc>)
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
allocator_type::deallocate_aligned(p, alignment);
#if __has_builtin(__builtin_operator_delete)
__builtin_operator_delete(p);
#else
::operator delete(p);
#endif
return;
}
else
#endif
{
if (p == nullptr)
if constexpr (::fast_io::details::has_deallocate_aligned_impl<alloc>)
{
return;
allocator_type::deallocate_aligned(p, alignment);
}
if (default_alignment < alignment)
else
{
p = reinterpret_cast<void **>(p)[-1];
if (p == nullptr)
{
return;
}
if (default_alignment < alignment)
{
p = reinterpret_cast<void **>(p)[-1];
}
allocator_type::deallocate(p);
}
allocator_type::deallocate(p);
}
}

static inline void deallocate_aligned_n(void *p, ::std::size_t alignment, ::std::size_t n) noexcept
static inline constexpr void deallocate_aligned_n(void *p, ::std::size_t alignment, ::std::size_t n) noexcept
requires(!has_status)
{
if constexpr (::fast_io::details::has_deallocate_aligned_n_impl<alloc>)
{
allocator_type::deallocate_aligned_n(p, alignment, n);
}
else if constexpr (::fast_io::details::has_deallocate_aligned_impl<alloc>)
#if __cpp_constexpr_dynamic_alloc >= 201907L
if (__builtin_is_constant_evaluated())
{
allocator_type::deallocate_aligned(p, alignment);
#if __has_builtin(__builtin_operator_delete)
__builtin_operator_delete(p);
#else
::operator delete(p);
#endif
return;
}
else
#endif
{
if (p == nullptr)
if constexpr (::fast_io::details::has_deallocate_aligned_n_impl<alloc>)
{
return;
allocator_type::deallocate_aligned_n(p, alignment, n);
}
if (default_alignment < alignment)
else if constexpr (::fast_io::details::has_deallocate_aligned_impl<alloc>)
{
auto start{reinterpret_cast<void **>(p)[-1]};
n += static_cast<::std::size_t>(reinterpret_cast<char unsigned *>(p) - reinterpret_cast<char unsigned *>(start));
p = start;
}
if constexpr (::fast_io::details::has_deallocate_impl<alloc>)
{
allocator_type::deallocate(p);
allocator_type::deallocate_aligned(p, alignment);
}
else
{
allocator_type::deallocate_n(p, n);
if (p == nullptr)
{
return;
}
if (default_alignment < alignment)
{
auto start{reinterpret_cast<void **>(p)[-1]};
n += static_cast<::std::size_t>(reinterpret_cast<char unsigned *>(p) - reinterpret_cast<char unsigned *>(start));
p = start;
}
if constexpr (::fast_io::details::has_deallocate_impl<alloc>)
{
allocator_type::deallocate(p);
}
else
{
allocator_type::deallocate_n(p, n);
}
}
}
}
Expand Down
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