Modest performance improvement for std::string's operator==.
llvm-svn: 180072
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 210051548ea01357cc834ce8917559ca32b7a137
diff --git a/include/string b/include/string
index de668bb..fa44f68 100644
--- a/include/string
+++ b/include/string
@@ -1462,6 +1462,11 @@
int compare(size_type __pos1, size_type __n1, const_pointer __s, size_type __n2) const;
_LIBCPP_INLINE_VISIBILITY bool __invariants() const;
+
+ _LIBCPP_INLINE_VISIBILITY
+ bool __is_long() const _NOEXCEPT
+ {return bool(__r_.first().__s.__size_ & __short_mask);}
+
private:
_LIBCPP_INLINE_VISIBILITY
allocator_type& __alloc() _NOEXCEPT
@@ -1471,10 +1476,6 @@
{return __r_.second();}
_LIBCPP_INLINE_VISIBILITY
- bool __is_long() const _NOEXCEPT
- {return bool(__r_.first().__s.__size_ & __short_mask);}
-
- _LIBCPP_INLINE_VISIBILITY
void __set_short_size(size_type __s) _NOEXCEPT
#if _LIBCPP_BIG_ENDIAN
{__r_.first().__s.__size_ = (unsigned char)(__s);}
@@ -3561,9 +3562,29 @@
operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
{
- return __lhs.size() == __rhs.size() && _Traits::compare(__lhs.data(),
- __rhs.data(),
- __lhs.size()) == 0;
+ size_t __lhs_sz = __lhs.size();
+ return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
+ __rhs.data(),
+ __lhs_sz) == 0;
+}
+
+template<class _Allocator>
+_LIBCPP_INLINE_VISIBILITY inline
+bool
+operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
+ const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
+{
+ size_t __lhs_sz = __lhs.size();
+ if (__lhs_sz != __rhs.size())
+ return false;
+ const char* __lp = __lhs.data();
+ const char* __rp = __rhs.data();
+ if (__lhs.__is_long())
+ return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
+ for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
+ if (*__lp != *__rp)
+ return false;
+ return true;
}
template<class _CharT, class _Traits, class _Allocator>