[libcxx-commits] [PATCH] D102005: [libcxx]: Unroll std::find on AIX

[Ettore Tiotto via Phabricator via libcxx-commits]

etiotto created this revision.
etiotto added reviewers: jasonliu, xingxue.
etiotto added a project: libc++.
Herald added a subscriber: libcxx-commits.
etiotto requested review of this revision.

This patch specializes the std::find implementation on AIX to unroll the while loop in that function for RandomAccessIterators.


Repository:
  rCXX libc++

https://reviews.llvm.org/D102005

Files:
  libcxx/include/algorithm


Index: libcxx/include/algorithm
===================================================================
--- libcxx/include/algorithm
+++ libcxx/include/algorithm
@@ -919,6 +919,64 @@
 
 // find
 
+#if defined(_AIX)
+
+template <class _InputIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_InputIterator
+__find(_InputIterator __first, _InputIterator __last, const _Tp& __value_, input_iterator_tag)
+{
+    for (; __first != __last; ++__first)
+        if (*__first == __value_)
+            break;
+    return __first;
+}
+
+template <class _RandomAccessIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_RandomAccessIterator
+__find(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value_, random_access_iterator_tag)
+{
+    typename iterator_traits<_RandomAccessIterator>::difference_type __d = (__last - __first);
+    while (__d >= 4) {
+        if (*__first == __value_)
+            return __first;
+        ++__first;
+
+        if (*__first == __value_)
+            return __first;
+        ++__first;
+
+        if (*__first == __value_)
+            return __first;
+        ++__first;
+
+        if (*__first == __value_)
+            return __first;
+        ++__first;
+
+        __d -= 4;
+    }
+
+    for (; __first != __last; ++__first)
+        if (*__first == __value_)
+            break;
+    return __first;
+}
+
+template <class _InputIterator, class _Tp>
+_LIBCPP_NODISCARD_EXT inline
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
+_InputIterator
+find(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
+{
+    return __find(__first, __last, __value_, typename iterator_traits<_InputIterator>::iterator_category());
+}
+
+#else
+
 template <class _InputIterator, class _Tp>
 _LIBCPP_NODISCARD_EXT inline
 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
@@ -930,6 +988,7 @@
             break;
     return __first;
 }
+#endif
 
 // find_if
 


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