Revert "Bug 39129: Speeding up partition_point/lower_bound/upper_bound/ by using unsigned division by 2 when possible."
This reverts r345525. I'm reverting because that patch apparently caused
a regression on certain platforms (see https://reviews.llvm.org/D53994).
Since we don't fully understand the reasons for the regression, I'm
reverting until we can provide a fix we understand.
llvm-svn: 345893
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: e0a724ef9c897b29be40c8b284ad4485d84effff
diff --git a/include/algorithm b/include/algorithm
index f119d25..beee6b5 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -750,32 +750,6 @@
bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
};
-// Perform division by two quickly for positive integers (llvm.org/PR39129)
-
-template <typename _Integral>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-typename enable_if
-<
- is_integral<_Integral>::value,
- _Integral
->::type
-__half_positive(_Integral __value)
-{
- return static_cast<_Integral>(static_cast<typename make_unsigned<_Integral>::type>(__value) / 2);
-}
-
-template <typename _Tp>
-_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-typename enable_if
-<
- !is_integral<_Tp>::value,
- _Tp
->::type
-__half_positive(_Tp __value)
-{
- return __value / 2;
-}
-
#ifdef _LIBCPP_DEBUG
template <class _Compare>
@@ -3228,7 +3202,7 @@
difference_type __len = _VSTD::distance(__first, __last);
while (__len != 0)
{
- difference_type __l2 = _VSTD::__half_positive(__len);
+ difference_type __l2 = __len / 2;
_ForwardIterator __m = __first;
_VSTD::advance(__m, __l2);
if (__pred(*__m))
@@ -4095,7 +4069,7 @@
difference_type __len = _VSTD::distance(__first, __last);
while (__len != 0)
{
- difference_type __l2 = _VSTD::__half_positive(__len);
+ difference_type __l2 = __len / 2;
_ForwardIterator __m = __first;
_VSTD::advance(__m, __l2);
if (__comp(*__m, __value_))
@@ -4137,7 +4111,7 @@
difference_type __len = _VSTD::distance(__first, __last);
while (__len != 0)
{
- difference_type __l2 = _VSTD::__half_positive(__len);
+ difference_type __l2 = __len / 2;
_ForwardIterator __m = __first;
_VSTD::advance(__m, __l2);
if (__comp(__value_, *__m))
@@ -4179,7 +4153,7 @@
difference_type __len = _VSTD::distance(__first, __last);
while (__len != 0)
{
- difference_type __l2 = _VSTD::__half_positive(__len);
+ difference_type __l2 = __len / 2;
_ForwardIterator __m = __first;
_VSTD::advance(__m, __l2);
if (__comp(*__m, __value_))