[libcxx-commits] [libcxx] [libc++][NFC] Simplify string a bit (PR #127135)
Peng Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Mon Feb 24 17:45:02 PST 2025
https://github.com/winner245 updated https://github.com/llvm/llvm-project/pull/127135
>From 596189ec32196d03b94d485c07244f3a5fd8f47e Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Thu, 13 Feb 2025 17:03:18 -0500
Subject: [PATCH 1/2] Simplify string a bit
---
libcxx/include/string | 87 ++++++++++++++++++-------------------------
1 file changed, 36 insertions(+), 51 deletions(-)
diff --git a/libcxx/include/string b/libcxx/include/string
index 7b86bbe5bffa7..01d8c40edb95b 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -235,9 +235,9 @@ public:
template <class T>
basic_string& insert(size_type pos1, const T& t); // constexpr since C++20
basic_string& insert(size_type pos1, const basic_string& str,
- size_type pos2, size_type n); // constexpr since C++20
+ size_type pos2, size_type n2=npos); // constexpr since C++20
template <class T>
- basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17, constexpr since C++20
+ basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n=npos); // C++17, constexpr since C++20
basic_string& insert(size_type pos, const value_type* s, size_type n=npos); // C++14, constexpr since C++20
basic_string& insert(size_type pos, const value_type* s); // constexpr since C++20
basic_string& insert(size_type pos, size_type n, value_type c); // constexpr since C++20
@@ -260,7 +260,7 @@ public:
size_type pos2, size_type n2=npos); // C++14, constexpr since C++20
template <class T>
basic_string& replace(size_type pos1, size_type n1, const T& t,
- size_type pos2, size_type n); // C++17, constexpr since C++20
+ size_type pos2, size_type n2=npos); // C++17, constexpr since C++20
basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2); // constexpr since C++20
basic_string& replace(size_type pos, size_type n1, const value_type* s); // constexpr since C++20
basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c); // constexpr since C++20
@@ -2303,7 +2303,7 @@ private:
if (!__str.__is_long()) {
if (__is_long()) {
__annotate_delete();
- __alloc_traits::deallocate(__alloc_, __get_long_pointer(), capacity() + 1);
+ __alloc_traits::deallocate(__alloc_, __get_long_pointer(), __get_long_cap());
__rep_ = __rep();
}
__alloc_ = __str.__alloc_;
@@ -2318,7 +2318,7 @@ private:
__alloc_ = std::move(__a);
__set_long_pointer(__allocation.ptr);
__set_long_cap(__allocation.count);
- __set_long_size(__str.size());
+ __set_long_size(__str.__get_long_size());
}
}
}
@@ -2437,8 +2437,8 @@ template <class _CharT,
class _Traits,
class _Allocator = allocator<_CharT>,
class = enable_if_t<__is_allocator<_Allocator>::value> >
-explicit basic_string(basic_string_view<_CharT, _Traits>,
- const _Allocator& = _Allocator()) -> basic_string<_CharT, _Traits, _Allocator>;
+explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
+ -> basic_string<_CharT, _Traits, _Allocator>;
template <class _CharT,
class _Traits,
@@ -2701,20 +2701,19 @@ template <class _CharT, class _Traits, class _Allocator>
template <bool __is_short>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(const value_type* __s, size_type __n) {
- size_type __cap = __is_short ? static_cast<size_type>(__min_cap) : __get_long_cap();
- if (__n < __cap) {
- size_type __old_size = __is_short ? __get_short_size() : __get_long_size();
+ size_type __cap = capacity();
+ size_type __old_size = size();
+ if (__n <= __cap) {
if (__n > __old_size)
__annotate_increase(__n - __old_size);
- pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
- __is_short ? __set_short_size(__n) : __set_long_size(__n);
+ pointer __p =
+ __is_short ? (__set_short_size(__n), __get_short_pointer()) : (__set_long_size(__n), __get_long_pointer());
traits_type::copy(std::__to_address(__p), __s, __n);
traits_type::assign(__p[__n], value_type());
if (__old_size > __n)
__annotate_shrink(__old_size);
} else {
- 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, __n - __cap, __old_size, 0, __old_size, __n, __s);
}
return *this;
}
@@ -2722,17 +2721,16 @@ basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(const value_type* _
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s, size_type __n) {
- size_type __cap = capacity();
+ size_type __cap = capacity();
+ size_type __old_size = size();
if (__cap >= __n) {
- size_type __old_size = size();
if (__n > __old_size)
__annotate_increase(__n - __old_size);
value_type* __p = std::__to_address(__get_pointer());
traits_type::move(__p, __s, __n);
return __null_terminate_at(__p, __n);
} else {
- size_type __sz = size();
- __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
+ __grow_by_and_replace(__cap, __n - __cap, __old_size, 0, __old_size, __n, __s);
return *this;
}
}
@@ -2750,8 +2748,7 @@ basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
size_type __cap = capacity();
size_type __old_size = size();
if (__cap < __n) {
- size_type __sz = size();
- __grow_by_without_replace(__cap, __n - __cap, __sz, 0, __sz);
+ __grow_by_without_replace(__cap, __n - __cap, __old_size, 0, __old_size);
__annotate_increase(__n);
} else if (__n > __old_size)
__annotate_increase(__n - __old_size);
@@ -2763,17 +2760,10 @@ basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c) {
- pointer __p;
size_type __old_size = size();
if (__old_size == 0)
__annotate_increase(1);
- if (__is_long()) {
- __p = __get_long_pointer();
- __set_long_size(1);
- } else {
- __p = __get_short_pointer();
- __set_short_size(1);
- }
+ pointer __p = __is_long() ? (__set_long_size(1), __get_long_pointer()) : (__set_short_size(1), __get_short_pointer());
traits_type::assign(*__p, __c);
traits_type::assign(*++__p, value_type());
if (__old_size > 1)
@@ -2789,8 +2779,8 @@ basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
if (!__is_long()) {
if (!__str.__is_long()) {
size_type __old_size = __get_short_size();
- if (__get_short_size() < __str.__get_short_size())
- __annotate_increase(__str.__get_short_size() - __get_short_size());
+ if (__old_size < __str.__get_short_size())
+ __annotate_increase(__str.__get_short_size() - __old_size);
__rep_ = __str.__rep_;
if (__old_size > __get_short_size())
__annotate_shrink(__old_size);
@@ -2957,10 +2947,11 @@ template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s) {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::assign received nullptr");
- return __builtin_constant_p(*__s)
- ? (__fits_in_sso(traits_type::length(__s)) ? __assign_short(__s, traits_type::length(__s))
- : __assign_external(__s, traits_type::length(__s)))
- : __assign_external(__s);
+ if (__builtin_constant_p(*__s)) {
+ const size_type __n = traits_type::length(__s);
+ return __fits_in_sso(__n) ? __assign_short(__s, __n) : __assign_external(__s, __n);
+ }
+ return __assign_external(__s);
}
// append
@@ -3032,18 +3023,11 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::pu
}
if (__sz == __cap) {
__grow_by_without_replace(__cap, 1, __sz, __sz, 0);
- __annotate_increase(1);
__is_short = false; // the string is always long after __grow_by
- } else
- __annotate_increase(1);
- pointer __p = __get_pointer();
- if (__is_short) {
- __p = __get_short_pointer() + __sz;
- __set_short_size(__sz + 1);
- } else {
- __p = __get_long_pointer() + __sz;
- __set_long_size(__sz + 1);
}
+ __annotate_increase(1);
+ pointer __p = __is_short ? (__set_short_size(__sz + 1), __get_short_pointer() + __sz)
+ : (__set_long_size(__sz + 1), __get_long_pointer() + __sz);
traits_type::assign(*__p, __c);
traits_type::assign(*++__p, value_type());
}
@@ -3420,11 +3404,13 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT {
- size_type __old_size = size();
+ size_type __old_size;
if (__is_long()) {
+ __old_size = __get_long_size();
traits_type::assign(*__get_long_pointer(), value_type());
__set_long_size(0);
} else {
+ __old_size = __get_short_size();
traits_type::assign(*__get_short_pointer(), value_type());
__set_short_size(0);
}
@@ -3482,11 +3468,12 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
_LIBCPP_ASSERT_INTERNAL(__is_long(), "Trying to shrink small string");
// We're a long string and we're shrinking into the small buffer.
+ auto __ptr = __get_long_pointer();
+ auto __size = __get_long_size();
+ auto __cap = __get_long_cap();
+
if (__fits_in_sso(__target_capacity)) {
__annotation_guard __g(*this);
- auto __ptr = __get_long_pointer();
- auto __size = __get_long_size();
- auto __cap = __get_long_cap();
traits_type::copy(std::__to_address(__get_short_pointer()), std::__to_address(__ptr), __size + 1);
__set_short_size(__size);
__alloc_traits::deallocate(__alloc_, __ptr, __cap);
@@ -3497,7 +3484,6 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
try {
# endif // _LIBCPP_HAS_EXCEPTIONS
__annotation_guard __g(*this);
- auto __size = size();
auto __allocation = std::__allocate_at_least(__alloc_, __target_capacity + 1);
// The Standard mandates shrink_to_fit() does not increase the capacity.
@@ -3509,9 +3495,8 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
}
__begin_lifetime(__allocation.ptr, __allocation.count);
- auto __ptr = __get_long_pointer();
traits_type::copy(std::__to_address(__allocation.ptr), std::__to_address(__ptr), __size + 1);
- __alloc_traits::deallocate(__alloc_, __ptr, __get_long_cap());
+ __alloc_traits::deallocate(__alloc_, __ptr, __cap);
__set_long_cap(__allocation.count);
__set_long_pointer(__allocation.ptr);
# if _LIBCPP_HAS_EXCEPTIONS
>From d897bacb33457862dd8103c30f497dddf2ae6eaf Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Thu, 20 Feb 2025 11:05:35 -0500
Subject: [PATCH 2/2] Address philnik777's suggestions
---
libcxx/include/string | 77 ++++++++++++++++++++++++++++---------------
1 file changed, 50 insertions(+), 27 deletions(-)
diff --git a/libcxx/include/string b/libcxx/include/string
index 01d8c40edb95b..99e85b9f71f67 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -2360,8 +2360,14 @@ private:
size_type __old_size = size();
if (__n > __old_size)
__annotate_increase(__n - __old_size);
- pointer __p =
- __is_long() ? (__set_long_size(__n), __get_long_pointer()) : (__set_short_size(__n), __get_short_pointer());
+ pointer __p;
+ if (__is_long()) {
+ __set_long_size(__n);
+ __p = __get_long_pointer();
+ } else {
+ __set_short_size(__n);
+ __p = __get_short_pointer();
+ }
traits_type::move(std::__to_address(__p), __s, __n);
traits_type::assign(__p[__n], value_type());
if (__old_size > __n)
@@ -2701,19 +2707,25 @@ template <class _CharT, class _Traits, class _Allocator>
template <bool __is_short>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(const value_type* __s, size_type __n) {
- size_type __cap = capacity();
- size_type __old_size = size();
- if (__n <= __cap) {
- if (__n > __old_size)
- __annotate_increase(__n - __old_size);
- pointer __p =
- __is_short ? (__set_short_size(__n), __get_short_pointer()) : (__set_long_size(__n), __get_long_pointer());
+ const auto __cap = __is_short ? static_cast<size_type>(__min_cap) : __get_long_cap();
+ const auto __sz = __is_short ? __get_short_size() : __get_long_size();
+ if (__n < __cap) {
+ if (__n > __sz)
+ __annotate_increase(__n - __sz);
+ pointer __p;
+ if (__is_short) {
+ __p = __get_short_pointer();
+ __set_short_size(__n);
+ } else {
+ __p = __get_long_pointer();
+ __set_long_size(__n);
+ }
traits_type::copy(std::__to_address(__p), __s, __n);
traits_type::assign(__p[__n], value_type());
- if (__old_size > __n)
- __annotate_shrink(__old_size);
+ if (__sz > __n)
+ __annotate_shrink(__sz);
} else {
- __grow_by_and_replace(__cap, __n - __cap, __old_size, 0, __old_size, __n, __s);
+ __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
}
return *this;
}
@@ -2721,16 +2733,16 @@ basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(const value_type* _
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s, size_type __n) {
- size_type __cap = capacity();
- size_type __old_size = size();
+ const auto __cap = capacity();
+ const auto __sz = size();
if (__cap >= __n) {
- if (__n > __old_size)
- __annotate_increase(__n - __old_size);
+ if (__n > __sz)
+ __annotate_increase(__n - __sz);
value_type* __p = std::__to_address(__get_pointer());
traits_type::move(__p, __s, __n);
return __null_terminate_at(__p, __n);
} else {
- __grow_by_and_replace(__cap, __n - __cap, __old_size, 0, __old_size, __n, __s);
+ __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
return *this;
}
}
@@ -2763,7 +2775,14 @@ basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c) {
size_type __old_size = size();
if (__old_size == 0)
__annotate_increase(1);
- pointer __p = __is_long() ? (__set_long_size(1), __get_long_pointer()) : (__set_short_size(1), __get_short_pointer());
+ pointer __p;
+ if (__is_long()) {
+ __set_long_size(1);
+ __p = __get_long_pointer();
+ } else {
+ __set_short_size(1);
+ __p = __get_short_pointer();
+ }
traits_type::assign(*__p, __c);
traits_type::assign(*++__p, value_type());
if (__old_size > 1)
@@ -2947,10 +2966,8 @@ template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s) {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::assign received nullptr");
- if (__builtin_constant_p(*__s)) {
- const size_type __n = traits_type::length(__s);
- return __fits_in_sso(__n) ? __assign_short(__s, __n) : __assign_external(__s, __n);
- }
+ if (auto __len = traits_type::length(__s); __builtin_constant_p(__len) && __fits_in_sso(__len))
+ return __assign_short(__s, __len);
return __assign_external(__s);
}
// append
@@ -3026,8 +3043,14 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::pu
__is_short = false; // the string is always long after __grow_by
}
__annotate_increase(1);
- pointer __p = __is_short ? (__set_short_size(__sz + 1), __get_short_pointer() + __sz)
- : (__set_long_size(__sz + 1), __get_long_pointer() + __sz);
+ pointer __p;
+ if (__is_short) {
+ __p = __get_short_pointer() + __sz;
+ __set_short_size(__sz + 1);
+ } else {
+ __p = __get_long_pointer() + __sz;
+ __set_long_size(__sz + 1);
+ }
traits_type::assign(*__p, __c);
traits_type::assign(*++__p, value_type());
}
@@ -3468,9 +3491,9 @@ inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocat
_LIBCPP_ASSERT_INTERNAL(__is_long(), "Trying to shrink small string");
// We're a long string and we're shrinking into the small buffer.
- auto __ptr = __get_long_pointer();
- auto __size = __get_long_size();
- auto __cap = __get_long_cap();
+ const auto __ptr = __get_long_pointer();
+ const auto __size = __get_long_size();
+ const auto __cap = __get_long_cap();
if (__fits_in_sso(__target_capacity)) {
__annotation_guard __g(*this);
More information about the libcxx-commits
mailing list