[libcxx-commits] [libcxx] [libc++] Refactor basic_string::__grow_by calls (PR #126034)
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Feb 6 01:37:35 PST 2025
https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/126034
This patch introduces a few wrapper functions around `__grow_by` to make
it clearer what the intention of the different calls is. Later these can
probably be implemented in a simpler manner than `__grow_by`.
>From 2d084468cf7bef33d0ef79b7707005caa3ce4e59 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Thu, 6 Feb 2025 09:32:53 +0100
Subject: [PATCH] [libc++] Refactor basic_string::__grow_by calls
This patch introduces a few wrapper functions around `__grow_by` to make
it clearer what the intention of the different calls is. Later these can
probably be implemented in a simpler manner than `__grow_by`.
---
libcxx/include/string | 68 +++++++++++++++++++++++--------------------
1 file changed, 36 insertions(+), 32 deletions(-)
diff --git a/libcxx/include/string b/libcxx/include/string
index b7f2d122694639..9c65cfec7e19cc 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1945,7 +1945,7 @@ private:
if (__n_move != 0)
traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
} else {
- __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
+ __grow_to_with_hole(__sz + __n, __ip, __n);
__p = std::__to_address(__get_long_pointer());
}
__sz += __n;
@@ -2141,20 +2141,15 @@ private:
# if _LIBCPP_ABI_VERSION >= 2 // We want to use the function in the dylib in ABIv1
_LIBCPP_HIDE_FROM_ABI
# endif
- _LIBCPP_DEPRECATED_("use __grow_by_without_replace") void __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 = 0);
- _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __grow_by_without_replace(
+ _LIBCPP_DEPRECATED_("use __grow_to") void __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 = 0);
+ _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
+ __grow_to(size_type __new_cap, size_type __n_copy, size_type __n_del, size_type __n_add = 0);
_LIBCPP_CONSTEXPR_SINCE_CXX20 void __grow_by_and_replace(
size_type __old_cap,
size_type __delta_cap,
@@ -2164,6 +2159,22 @@ private:
size_type __n_add,
const value_type* __p_new_stuff);
+ // Allocate a new buffer of size __new_cap and copy data from the old buffer from
+ // [old_buffer, old_buffer + __hole_loc) into [new_buffer, new_buffer + __hole_loc) and
+ // [old_buffer + __hole_loc) into [new_buffer + __hole_loc + __hole_size).
+ //
+ // This means that all the data from the old buffer is copied into the new one, but an uninitialized area
+ // [new_buffer + __hole_loc, new_buffer + __hole_loc + __hole_size) is there as well, allowing insertion operations
+ _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
+ __grow_to_with_hole(size_type __new_cap, size_type __hole_loc, size_type __hole_size) {
+ __grow_to(__new_cap, __hole_loc, 0, __hole_size);
+ }
+
+ // Allocate a new buffer of size __capacity and replace the old one with it, but do not copy any data
+ _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __uninitialized_reallocate(size_type __capacity) {
+ __grow_to(__capacity, 0, size());
+ }
+
// __assign_no_alias is invoked for assignment operations where we
// have proof that the input does not alias the current instance.
// For example, operator=(basic_string) performs a 'self' check.
@@ -2559,7 +2570,7 @@ void _LIBCPP_CONSTEXPR_SINCE_CXX20
# if _LIBCPP_ABI_VERSION >= 2 // We want to use the function in the dylib in ABIv1
_LIBCPP_HIDE_FROM_ABI
# endif
-_LIBCPP_DEPRECATED_("use __grow_by_without_replace") basic_string<_CharT, _Traits, _Allocator>::__grow_by(
+basic_string<_CharT, _Traits, _Allocator>::__grow_by(
size_type __old_cap,
size_type __delta_cap,
size_type __old_sz,
@@ -2588,18 +2599,15 @@ _LIBCPP_DEPRECATED_("use __grow_by_without_replace") basic_string<_CharT, _Trait
}
template <class _CharT, class _Traits, class _Allocator>
-void _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI
-basic_string<_CharT, _Traits, _Allocator>::__grow_by_without_replace(
- size_type __old_cap,
- size_type __delta_cap,
- size_type __old_sz,
- size_type __n_copy,
- size_type __n_del,
- size_type __n_add) {
+void _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI basic_string<_CharT, _Traits, _Allocator>::__grow_to(
+ size_type __new_cap, size_type __n_copy, size_type __n_del, size_type __n_add) {
__annotate_delete();
auto __guard = std::__make_scope_guard(__annotate_new_size(*this));
+
+ auto __old_cap = capacity();
+ auto __old_sz = size();
_LIBCPP_SUPPRESS_DEPRECATED_PUSH
- __grow_by(__old_cap, __delta_cap, __old_sz, __n_copy, __n_del, __n_add);
+ __grow_by(__old_cap, __new_cap - __old_cap, __old_sz, __n_copy, __n_del, __n_add);
_LIBCPP_SUPPRESS_DEPRECATED_POP
__set_long_size(__old_sz - __n_del + __n_add);
}
@@ -2660,7 +2668,7 @@ basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
size_type __old_size = size();
if (__cap < __n) {
size_type __sz = size();
- __grow_by_without_replace(__cap, __n - __cap, __sz, 0, __sz);
+ __uninitialized_reallocate(__n);
__annotate_increase(__n);
} else if (__n > __old_size)
__annotate_increase(__n - __old_size);
@@ -2819,8 +2827,7 @@ basic_string<_CharT, _Traits, _Allocator>::__assign_trivial(_Iterator __first, _
// thus no reallocation would happen.
// 2. In the exotic case where the input range is the byte representation of the string itself, the string
// object itself stays valid even if reallocation happens.
- size_type __sz = size();
- __grow_by_without_replace(__cap, __n - __cap, __sz, 0, __sz);
+ __uninitialized_reallocate(__n);
__annotate_increase(__n);
} else if (__n > __old_size)
__annotate_increase(__n - __old_size);
@@ -2899,8 +2906,7 @@ basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
if (__n) {
size_type __cap = capacity();
size_type __sz = size();
- if (__cap - __sz < __n)
- __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
+ reserve(__sz + __n);
__annotate_increase(__n);
pointer __p = __get_pointer();
traits_type::assign(std::__to_address(__p) + __sz, __n, __c);
@@ -2917,8 +2923,7 @@ basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
if (__n) {
size_type __cap = capacity();
size_type __sz = size();
- if (__cap - __sz < __n)
- __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
+ reserve(__sz + __n);
__annotate_increase(__n);
pointer __p = __get_pointer();
__sz += __n;
@@ -2940,7 +2945,7 @@ _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::pu
__sz = __get_long_size();
}
if (__sz == __cap) {
- __grow_by_without_replace(__cap, 1, __sz, __sz, 0);
+ reserve(__cap + 1);
__annotate_increase(1);
__is_short = false; // the string is always long after __grow_by
} else
@@ -2966,8 +2971,7 @@ basic_string<_CharT, _Traits, _Allocator>::append(_ForwardIterator __first, _For
size_type __n = static_cast<size_type>(std::distance(__first, __last));
if (__n) {
if (__string_is_trivial_iterator<_ForwardIterator>::value && !__addr_in_range(*__first)) {
- if (__cap - __sz < __n)
- __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
+ reserve(__sz + __n);
__annotate_increase(__n);
auto __end = __copy_non_overlapping_range(__first, __last, std::__to_address(__get_pointer() + __sz));
traits_type::assign(*__end, value_type());
@@ -3056,7 +3060,7 @@ basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n
if (__n_move != 0)
traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
} else {
- __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
+ __grow_to_with_hole(__sz + __n, __pos, __n);
__p = std::__to_address(__get_long_pointer());
}
traits_type::assign(__p + __pos, __n, __c);
@@ -3140,7 +3144,7 @@ basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_ty
size_type __cap = capacity();
value_type* __p;
if (__cap == __sz) {
- __grow_by_without_replace(__cap, 1, __sz, __ip, 0, 1);
+ __grow_to_with_hole(__cap + 1, __ip, 1);
__p = std::__to_address(__get_long_pointer());
} else {
__annotate_increase(1);
@@ -3221,7 +3225,7 @@ basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __
traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
}
} else {
- __grow_by_without_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
+ __grow_to(__sz - __n1 + __n2, __pos, __n1, __n2);
__p = std::__to_address(__get_long_pointer());
}
traits_type::assign(__p + __pos, __n2, __c);
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