[libc++] Simplify single-iterator __bit_iterator algorithm specializations
The single-iterator algorithms have an implementation for `false` and `true`, which are almost identical. Instead of writing two functions, this refactors the code to take the value searched for as a template parameter. This avoids a lot of code duplication and makes it easier to reason about the algorithm and their difference.
Reviewed By: #libc, Mordante
Spies: Mordante, libcxx-commits
Differential Revision: https://reviews.llvm.org/D156033
diff --git a/libcxx/include/__bit_reference b/libcxx/include/__bit_reference
index a6bb6d4..912c572 100644
--- a/libcxx/include/__bit_reference
+++ b/libcxx/include/__bit_reference
@@ -179,47 +179,18 @@
__bit_const_reference& operator=(const __bit_const_reference&) = delete;
};
-// find
-
-template <class _Cp, bool _IsConst>
-_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>
-__find_bool_true(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
-{
- typedef __bit_iterator<_Cp, _IsConst> _It;
- typedef typename _It::__storage_type __storage_type;
- const int __bits_per_word = _It::__bits_per_word;
- // do first partial word
- if (__first.__ctz_ != 0)
- {
- __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
- __storage_type __dn = _VSTD::min(__clz_f, __n);
- __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
- __storage_type __b = *__first.__seg_ & __m;
- if (__b)
- return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
- if (__n == __dn)
- return __first + __n;
- __n -= __dn;
- ++__first.__seg_;
- }
- // do middle whole words
- for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
- if (*__first.__seg_)
- return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(*__first.__seg_)));
- // do last partial word
- if (__n > 0)
- {
- __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
- __storage_type __b = *__first.__seg_ & __m;
- if (__b)
- return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
- }
- return _It(__first.__seg_, static_cast<unsigned>(__n));
+template <bool _Invert, class _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp __invert_if(_Tp __v) {
+ if (_Invert)
+ return ~__v;
+ return __v;
}
-template <class _Cp, bool _IsConst>
+// find
+
+template <bool _ToFind, class _Cp, bool _IsConst>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI __bit_iterator<_Cp, _IsConst>
-__find_bool_false(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
+__find_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
{
typedef __bit_iterator<_Cp, _IsConst> _It;
typedef typename _It::__storage_type __storage_type;
@@ -230,7 +201,7 @@
__storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
__storage_type __dn = _VSTD::min(__clz_f, __n);
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
- __storage_type __b = ~*__first.__seg_ & __m;
+ __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
if (__b)
return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
if (__n == __dn)
@@ -239,9 +210,8 @@
++__first.__seg_;
}
// do middle whole words
- for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
- {
- __storage_type __b = ~*__first.__seg_;
+ for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word) {
+ __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_);
if (__b)
return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
}
@@ -249,7 +219,7 @@
if (__n > 0)
{
__storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
- __storage_type __b = ~*__first.__seg_ & __m;
+ __storage_type __b = std::__invert_if<!_ToFind>(*__first.__seg_) & __m;
if (__b)
return _It(__first.__seg_, static_cast<unsigned>(_VSTD::__libcpp_ctz(__b)));
}
@@ -262,15 +232,15 @@
find(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value)
{
if (static_cast<bool>(__value))
- return _VSTD::__find_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first));
- return _VSTD::__find_bool_false(__first, static_cast<typename _Cp::size_type>(__last - __first));
+ return _VSTD::__find_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first));
+ return _VSTD::__find_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first));
}
// count
-template <class _Cp, bool _IsConst>
+template <bool _ToCount, class _Cp, bool _IsConst>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 typename __bit_iterator<_Cp, _IsConst>::difference_type
-__count_bool_true(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
+__count_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
{
typedef __bit_iterator<_Cp, _IsConst> _It;
typedef typename _It::__storage_type __storage_type;
@@ -283,49 +253,18 @@
__storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
__storage_type __dn = _VSTD::min(__clz_f, __n);
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
- __r = _VSTD::__libcpp_popcount(*__first.__seg_ & __m);
+ __r = _VSTD::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
__n -= __dn;
++__first.__seg_;
}
// do middle whole words
for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
- __r += _VSTD::__libcpp_popcount(*__first.__seg_);
+ __r += _VSTD::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_));
// do last partial word
if (__n > 0)
{
__storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
- __r += _VSTD::__libcpp_popcount(*__first.__seg_ & __m);
- }
- return __r;
-}
-
-template <class _Cp, bool _IsConst>
-_LIBCPP_HIDE_FROM_ABI typename __bit_iterator<_Cp, _IsConst>::difference_type
-__count_bool_false(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
-{
- typedef __bit_iterator<_Cp, _IsConst> _It;
- typedef typename _It::__storage_type __storage_type;
- typedef typename _It::difference_type difference_type;
- const int __bits_per_word = _It::__bits_per_word;
- difference_type __r = 0;
- // do first partial word
- if (__first.__ctz_ != 0)
- {
- __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
- __storage_type __dn = _VSTD::min(__clz_f, __n);
- __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
- __r = _VSTD::__libcpp_popcount(~*__first.__seg_ & __m);
- __n -= __dn;
- ++__first.__seg_;
- }
- // do middle whole words
- for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
- __r += _VSTD::__libcpp_popcount(~*__first.__seg_);
- // do last partial word
- if (__n > 0)
- {
- __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
- __r += _VSTD::__libcpp_popcount(~*__first.__seg_ & __m);
+ __r += _VSTD::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
}
return __r;
}
@@ -336,15 +275,15 @@
count(__bit_iterator<_Cp, _IsConst> __first, __bit_iterator<_Cp, _IsConst> __last, const _Tp& __value)
{
if (static_cast<bool>(__value))
- return _VSTD::__count_bool_true(__first, static_cast<typename _Cp::size_type>(__last - __first));
- return _VSTD::__count_bool_false(__first, static_cast<typename _Cp::size_type>(__last - __first));
+ return _VSTD::__count_bool<true>(__first, static_cast<typename _Cp::size_type>(__last - __first));
+ return _VSTD::__count_bool<false>(__first, static_cast<typename _Cp::size_type>(__last - __first));
}
// fill_n
-template <class _Cp>
+template <bool _FillValue, class _Cp>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
-__fill_n_false(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
+__fill_n(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
{
typedef __bit_iterator<_Cp, false> _It;
typedef typename _It::__storage_type __storage_type;
@@ -355,51 +294,26 @@
__storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
__storage_type __dn = _VSTD::min(__clz_f, __n);
__storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
- *__first.__seg_ &= ~__m;
+ if (_FillValue)
+ *__first.__seg_ |= __m;
+ else
+ *__first.__seg_ &= ~__m;
__n -= __dn;
++__first.__seg_;
}
// do middle whole words
__storage_type __nw = __n / __bits_per_word;
- std::fill_n(std::__to_address(__first.__seg_), __nw, 0);
+ std::fill_n(std::__to_address(__first.__seg_), __nw, _FillValue ? static_cast<__storage_type>(-1) : 0);
__n -= __nw * __bits_per_word;
// do last partial word
if (__n > 0)
{
__first.__seg_ += __nw;
__storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
- *__first.__seg_ &= ~__m;
- }
-}
-
-template <class _Cp>
-_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
-__fill_n_true(__bit_iterator<_Cp, false> __first, typename _Cp::size_type __n)
-{
- typedef __bit_iterator<_Cp, false> _It;
- typedef typename _It::__storage_type __storage_type;
- const int __bits_per_word = _It::__bits_per_word;
- // do first partial word
- if (__first.__ctz_ != 0)
- {
- __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
- __storage_type __dn = _VSTD::min(__clz_f, __n);
- __storage_type __m = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
- *__first.__seg_ |= __m;
- __n -= __dn;
- ++__first.__seg_;
- }
- // do middle whole words
- __storage_type __nw = __n / __bits_per_word;
- // __storage_type is always an unsigned type, so -1 sets all bits
- std::fill_n(std::__to_address(__first.__seg_), __nw, static_cast<__storage_type>(-1));
- __n -= __nw * __bits_per_word;
- // do last partial word
- if (__n > 0)
- {
- __first.__seg_ += __nw;
- __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
- *__first.__seg_ |= __m;
+ if (_FillValue)
+ *__first.__seg_ |= __m;
+ else
+ *__first.__seg_ &= ~__m;
}
}
@@ -411,9 +325,9 @@
if (__n > 0)
{
if (__value)
- _VSTD::__fill_n_true(__first, __n);
+ _VSTD::__fill_n<true>(__first, __n);
else
- _VSTD::__fill_n_false(__first, __n);
+ _VSTD::__fill_n<false>(__first, __n);
}
}
@@ -1276,13 +1190,9 @@
friend class __bit_const_reference<_Cp>;
friend class __bit_iterator<_Cp, true>;
template <class _Dp> friend struct __bit_array;
- template <class _Dp>
+ template <bool _FillValue, class _Dp>
_LIBCPP_CONSTEXPR_SINCE_CXX20
- friend void __fill_n_false(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
-
- template <class _Dp>
- _LIBCPP_CONSTEXPR_SINCE_CXX20
- friend void __fill_n_true(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
+ friend void __fill_n(__bit_iterator<_Dp, false> __first, typename _Dp::size_type __n);
template <class _Dp, bool _IC>
_LIBCPP_CONSTEXPR_SINCE_CXX20
@@ -1343,17 +1253,12 @@
friend bool equal(__bit_iterator<_Dp, _IC1>,
__bit_iterator<_Dp, _IC1>,
__bit_iterator<_Dp, _IC2>);
- template <class _Dp, bool _IC>
+ template <bool _ToFind, class _Dp, bool _IC>
_LIBCPP_CONSTEXPR_SINCE_CXX20
- friend __bit_iterator<_Dp, _IC> __find_bool_true(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
- template <class _Dp, bool _IC>
- _LIBCPP_CONSTEXPR_SINCE_CXX20
- friend __bit_iterator<_Dp, _IC> __find_bool_false(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
- template <class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
+ friend __bit_iterator<_Dp, _IC> __find_bool(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
+ template <bool _ToCount, class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23
- __count_bool_true(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
- template <class _Dp, bool _IC> friend typename __bit_iterator<_Dp, _IC>::difference_type
- __count_bool_false(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
+ __count_bool(__bit_iterator<_Dp, _IC>, typename _Dp::size_type);
};
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/bitset b/libcxx/include/bitset
index c63ee22..4da0a4f 100644
--- a/libcxx/include/bitset
+++ b/libcxx/include/bitset
@@ -1012,7 +1012,7 @@
size_t
bitset<_Size>::count() const _NOEXCEPT
{
- return static_cast<size_t>(_VSTD::__count_bool_true(base::__make_iter(0), _Size));
+ return static_cast<size_t>(_VSTD::__count_bool<true>(base::__make_iter(0), _Size));
}
template <size_t _Size>
