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libcxx/include/string

Show First 20 Lines • Show All 1,535 Lines • ▼ Show 20 Lines#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
size_type __recommend(size_type __s) _NOEXCEPT size_type __recommend(size_type __s) _NOEXCEPT
{ {
if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1; if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1;
size_type __guess = __align_it<sizeof(value_type) < __alignment ? size_type __guess = __align_it<sizeof(value_type) < __alignment ?
__alignment/sizeof(value_type) : 1 > (__s+1) - 1; __alignment/sizeof(value_type) : 1 > (__s+1) - 1;
if (__guess == __min_cap) ++__guess; if (__guess == __min_cap) ++__guess;
return __guess; return __guess;
} }
static _LIBCPP_INLINE_VISIBILITY size_type
__recommend_cap(size_type __cap) _NOEXCEPT {
return __align_it < sizeof(value_type) < __alignment
? __alignment / sizeof(value_type)
: 1 > (__cap);
}
inline inline
void __init(const value_type* __s, size_type __sz, size_type __reserve); void __init(const value_type* __s, size_type __sz, size_type __reserve);
inline inline
void __init(const value_type* __s, size_type __sz); void __init(const value_type* __s, size_type __sz);
inline inline
void __init(size_type __n, value_type __c); void __init(size_type __n, value_type __c);
▲ Show 20 Lines • Show All 105 Lines • ▼ Show 20 Lines void __move_assign_alloc(basic_string& __c, true_type)
__alloc() = _VSTD::move(__c.__alloc()); __alloc() = _VSTD::move(__c.__alloc());
} }
_LIBCPP_INLINE_VISIBILITY _LIBCPP_INLINE_VISIBILITY
void __move_assign_alloc(basic_string&, false_type) void __move_assign_alloc(basic_string&, false_type)
_NOEXCEPT _NOEXCEPT
{} {}
basic_string& __assign_external(const value_type* __s);
basic_string& __assign_external(const value_type* __s, size_type __n);
template <bool __is_short>
value_type* __resize(size_type __n);
inline value_type* __resize(size_type __n) {
return __is_long() ? __resize<false>(__n) : __resize<true>(__n);
}
inline value_type* __resize_small(size_type __n) _NOEXCEPT {
pointer __p = __is_long()
? (__set_long_size(__n), __get_long_pointer())
: (__set_short_size(__n), __get_short_pointer());
traits_type::assign(__p[__n], value_type());
return _VSTD::__to_address(__p);
}
inline basic_string& __assign_small_length(const value_type* __s,
size_type __n) {
value_type* p = (__n < __min_cap) ? __resize_small(__n) : __resize(__n);
if (__builtin_constant_p(*__s)) {
traits_type::copy(p, __s, __n);
} else {
traits_type::move(p, __s, __n);
}
return *this;
}
_LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators(); _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
_LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type); _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
friend basic_string operator+<>(const basic_string&, const basic_string&); friend basic_string operator+<>(const basic_string&, const basic_string&);
friend basic_string operator+<>(const value_type*, const basic_string&); friend basic_string operator+<>(const value_type*, const basic_string&);
friend basic_string operator+<>(value_type, const basic_string&); friend basic_string operator+<>(value_type, const basic_string&);
friend basic_string operator+<>(const basic_string&, const value_type*); friend basic_string operator+<>(const basic_string&, const value_type*);
friend basic_string operator+<>(const basic_string&, value_type); friend basic_string operator+<>(const basic_string&, value_type);
▲ Show 20 Lines • Show All 544 Lines • ▼ Show 20 Linesbasic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
__set_long_pointer(__p); __set_long_pointer(__p);
__set_long_cap(__cap+1); __set_long_cap(__cap+1);
__old_sz = __n_copy + __n_add + __sec_cp_sz; __old_sz = __n_copy + __n_add + __sec_cp_sz;
__set_long_size(__old_sz); __set_long_size(__old_sz);
traits_type::assign(__p[__old_sz], value_type()); traits_type::assign(__p[__old_sz], value_type());
} }
template <class _CharT, class _Traits, class _Allocator> template <class _CharT, class _Traits, class _Allocator>
template <bool __is_short>
_CharT* basic_string<_CharT, _Traits, _Allocator>::__resize(size_type __n) {
size_type __old_cap = __is_short ? __min_cap : __get_long_cap();
pointer __old_p = __is_short ? __get_short_pointer() : __get_long_pointer();
if (__n < __old_cap) {
__is_short ? __set_short_size(__n) : __set_long_size(__n);
return _VSTD::__to_address(__old_p);
}
const size_type __ms = max_size();
if (__n > __ms) this->__throw_length_error();
size_type __new_cap;
if (__is_short) {
__new_cap = __recommend_cap(_VSTD::max<size_type>(__n + 1, 32));
} else {
__new_cap = (__old_cap < __ms / 2 - __alignment)
? __recommend_cap(_VSTD::max(__n + 1, 2 * __old_cap))
: __ms;
}
pointer __p = __alloc_traits::allocate(__alloc(), __new_cap);
__invalidate_all_iterators();
__set_long_pointer(__p);
__is_short ? __set_short_size(__n) : __set_long_size(__n);
__set_long_cap(__new_cap);
if (!__is_short) {
__alloc_traits::deallocate(__alloc(), __old_p, __old_cap);
}
return __p;
}
template <class _CharT, class _Traits, class _Allocator>
void void
basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz, basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
size_type __n_copy, size_type __n_del, size_type __n_add) size_type __n_copy, size_type __n_del, size_type __n_add)
{ {
size_type __ms = max_size(); size_type __ms = max_size();
if (__delta_cap > __ms - __old_cap) if (__delta_cap > __ms - __old_cap)
this->__throw_length_error(); this->__throw_length_error();
pointer __old_p = __get_pointer(); pointer __old_p = __get_pointer();
Show All 34 Lines if (__n < __cap) {
size_type __sz = __is_short ? __get_short_size() : __get_long_size(); size_type __sz = __is_short ? __get_short_size() : __get_long_size();
__grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s); __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
} }
return *this; return *this;
} }
template <class _CharT, class _Traits, class _Allocator> template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator>& basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n) basic_string<_CharT, _Traits, _Allocator>::__assign_external(
{ const value_type* __s, size_type __n) {
_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
size_type __cap = capacity(); size_type __cap = capacity();
if (__cap >= __n) if (__cap >= __n) {
{
value_type* __p = _VSTD::__to_address(__get_pointer()); value_type* __p = _VSTD::__to_address(__get_pointer());
traits_type::move(__p, __s, __n); traits_type::move(__p, __s, __n);
traits_type::assign(__p[__n], value_type()); traits_type::assign(__p[__n], value_type());
__set_size(__n); __set_size(__n);
__invalidate_iterators_past(__n); __invalidate_iterators_past(__n);
} } else {
else
{
size_type __sz = size(); size_type __sz = size();
__grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s); __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
} }
return *this; return *this;
} }
template <class _CharT, class _Traits, class _Allocator> template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator>& basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
{
_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
return (__builtin_constant_p(__n) && __n <= 128 / sizeof(value_type))
ldionneUnsubmitted
Done
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It used to be __n <= ..., now it's __n < ... -- what am I missing?

ldionne: It used to be `__n <= ...`, now it's `__n < ...` -- what am I missing?
mvelsAuthorUnsubmitted
Done
ReplyInline Actions

The initial version was aimed at optimizing 2 things:

  • short optimization, i.e., [n] chars < min_cap guaranteed to fit inside any SSO or heap allocated string
  • small memcpy optimization, i.., n <= 128 which when inlined can be vectorized efficiently (i.e., a rough max memcpy inline)

For this change we should focus only on the former. The latter is better picked up as an FDO / LLVM compiler inlining opportunity.

mvels: The initial version was aimed at optimizing 2 things: - short optimization, i.e., [n] chars <…
? __assign_small_length(__s, __n)
: __assign_external(__s, __n);
}
template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c) basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
{ {
size_type __cap = capacity(); size_type __cap = capacity();
if (__cap < __n) if (__cap < __n)
{ {
size_type __sz = size(); size_type __sz = size();
__grow_by(__cap, __n - __cap, __sz, 0, __sz); __grow_by(__cap, __n - __cap, __sz, 0, __sz);
} }
▲ Show 20 Lines • Show All 166 Lines • ▼ Show 20 Linesbasic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
if (__pos > __sz) if (__pos > __sz)
this->__throw_out_of_range(); this->__throw_out_of_range();
return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos)); return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
} }
template <class _CharT, class _Traits, class _Allocator> template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator>& basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s) {
return __assign_external(__s, traits_type::length(__s));
}
template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s) basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
{ {
_LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr"); _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
return assign(__s, traits_type::length(__s)); return (__builtin_constant_p(*__s) && traits_type::length(__s) <= 128)
? __assign_small_length(__s, traits_type::length(__s))
: __assign_external(__s);
} }
// append // append
template <class _CharT, class _Traits, class _Allocator> template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator>& basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n) basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
{ {
_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr"); _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
size_type __cap = capacity(); size_type __cap = capacity();
▲ Show 20 Lines • Show All 1,982 Lines • Show Last 20 Lines