[libcxx-commits] [libcxx] [libc++][ranges] optimize the performance of `ranges::starts_with` (PR #84570)
Xiaoyang Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Mar 8 16:05:48 PST 2024
https://github.com/xiaoyang-sde updated https://github.com/llvm/llvm-project/pull/84570
>From 3a384218365b175e8884a91125efe4e07f9e500a Mon Sep 17 00:00:00 2001
From: Xiaoyang Liu <siujoeng.lau at gmail.com>
Date: Fri, 8 Mar 2024 13:43:39 -0800
Subject: [PATCH 1/3] [libc++][ranges] detect size mismatch in
'ranges::starts_with'
---
.../include/__algorithm/ranges_starts_with.h | 23 +++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/libcxx/include/__algorithm/ranges_starts_with.h b/libcxx/include/__algorithm/ranges_starts_with.h
index 90e184aa9bccc2..b39e1657a855ea 100644
--- a/libcxx/include/__algorithm/ranges_starts_with.h
+++ b/libcxx/include/__algorithm/ranges_starts_with.h
@@ -15,6 +15,7 @@
#include <__functional/identity.h>
#include <__functional/ranges_operations.h>
#include <__iterator/concepts.h>
+#include <__iterator/distance.h>
#include <__iterator/indirectly_comparable.h>
#include <__ranges/access.h>
#include <__ranges/concepts.h>
@@ -50,6 +51,17 @@ struct __fn {
_Pred __pred = {},
_Proj1 __proj1 = {},
_Proj2 __proj2 = {}) const {
+ if constexpr (sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2>) {
+ auto __n1 = ranges::distance(__first1, __last1);
+ auto __n2 = ranges::distance(__first2, __last2);
+ if (__n2 == 0) {
+ return true;
+ }
+ if (__n2 > __n1) {
+ return false;
+ }
+ }
+
return __mismatch::__fn::__go(
std::move(__first1),
std::move(__last1),
@@ -69,6 +81,17 @@ struct __fn {
requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
_Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const {
+ if constexpr (sized_range<_Range1> && sized_range<_Range2>) {
+ auto __n1 = ranges::size(__range1);
+ auto __n2 = ranges::size(__range2);
+ if (__n2 == 0) {
+ return true;
+ }
+ if (__n2 > __n1) {
+ return false;
+ }
+ }
+
return __mismatch::__fn::__go(
ranges::begin(__range1),
ranges::end(__range1),
>From 5f8773ea9dcedb1a7fbaf02fd7b145834c1b3cf3 Mon Sep 17 00:00:00 2001
From: Xiaoyang Liu <siujoeng.lau at gmail.com>
Date: Fri, 8 Mar 2024 13:44:51 -0800
Subject: [PATCH 2/3] [libc++][ranges] change the 'operator()' of
'ranges::starts_with' to 'static'
---
libcxx/include/__algorithm/ranges_starts_with.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/libcxx/include/__algorithm/ranges_starts_with.h b/libcxx/include/__algorithm/ranges_starts_with.h
index b39e1657a855ea..93409d5b109137 100644
--- a/libcxx/include/__algorithm/ranges_starts_with.h
+++ b/libcxx/include/__algorithm/ranges_starts_with.h
@@ -43,14 +43,14 @@ struct __fn {
class _Proj1 = identity,
class _Proj2 = identity>
requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr bool operator()(
_Iter1 __first1,
_Sent1 __last1,
_Iter2 __first2,
_Sent2 __last2,
_Pred __pred = {},
_Proj1 __proj1 = {},
- _Proj2 __proj2 = {}) const {
+ _Proj2 __proj2 = {}) {
if constexpr (sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2>) {
auto __n1 = ranges::distance(__first1, __last1);
auto __n2 = ranges::distance(__first2, __last2);
@@ -79,8 +79,8 @@ struct __fn {
class _Proj1 = identity,
class _Proj2 = identity>
requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(
- _Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const {
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr bool
+ operator()(_Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) {
if constexpr (sized_range<_Range1> && sized_range<_Range2>) {
auto __n1 = ranges::size(__range1);
auto __n2 = ranges::size(__range2);
>From 66fb3d8ae037ec041fa765650c71359d295b0ee8 Mon Sep 17 00:00:00 2001
From: Xiaoyang Liu <siujoeng.lau at gmail.com>
Date: Fri, 8 Mar 2024 16:05:28 -0800
Subject: [PATCH 3/3] [libc++][ranges] dispatch to 'ranges::equal' in
'ranges::starts_with'
---
.../include/__algorithm/ranges_starts_with.h | 87 +++++++++++--------
1 file changed, 50 insertions(+), 37 deletions(-)
diff --git a/libcxx/include/__algorithm/ranges_starts_with.h b/libcxx/include/__algorithm/ranges_starts_with.h
index 93409d5b109137..ebcc15555f5544 100644
--- a/libcxx/include/__algorithm/ranges_starts_with.h
+++ b/libcxx/include/__algorithm/ranges_starts_with.h
@@ -9,11 +9,12 @@
#ifndef _LIBCPP___ALGORITHM_RANGES_STARTS_WITH_H
#define _LIBCPP___ALGORITHM_RANGES_STARTS_WITH_H
-#include <__algorithm/in_in_result.h>
+#include <__algorithm/ranges_equal.h>
#include <__algorithm/ranges_mismatch.h>
#include <__config>
#include <__functional/identity.h>
#include <__functional/ranges_operations.h>
+#include <__functional/reference_wrapper.h>
#include <__iterator/concepts.h>
#include <__iterator/distance.h>
#include <__iterator/indirectly_comparable.h>
@@ -35,22 +36,15 @@ _LIBCPP_BEGIN_NAMESPACE_STD
namespace ranges {
namespace __starts_with {
struct __fn {
- template <input_iterator _Iter1,
- sentinel_for<_Iter1> _Sent1,
- input_iterator _Iter2,
- sentinel_for<_Iter2> _Sent2,
- class _Pred = ranges::equal_to,
- class _Proj1 = identity,
- class _Proj2 = identity>
- requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
- _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr bool operator()(
+ template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class _Pred, class _Proj1, class _Proj2>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr bool __starts_with_impl(
_Iter1 __first1,
_Sent1 __last1,
_Iter2 __first2,
_Sent2 __last2,
- _Pred __pred = {},
- _Proj1 __proj1 = {},
- _Proj2 __proj2 = {}) {
+ _Pred& __pred,
+ _Proj1& __proj1,
+ _Proj2& __proj2) {
if constexpr (sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2>) {
auto __n1 = ranges::distance(__first1, __last1);
auto __n2 = ranges::distance(__first2, __last2);
@@ -60,19 +54,50 @@ struct __fn {
if (__n2 > __n1) {
return false;
}
+
+ if constexpr (random_access_iterator<_Iter1> && random_access_iterator<_Iter2>) {
+ return ranges::equal(
+ std::move(__first1),
+ ranges::next(__first1, __n2),
+ std::move(__first2),
+ std::move(__last2),
+ std::ref(__pred),
+ std::ref(__proj1),
+ std::ref(__proj2));
+ }
}
- return __mismatch::__fn::__go(
+ return ranges::mismatch(
std::move(__first1),
std::move(__last1),
std::move(__first2),
std::move(__last2),
- __pred,
- __proj1,
- __proj2)
+ std::ref(__pred),
+ std::ref(__proj1),
+ std::ref(__proj2))
.in2 == __last2;
}
+ template <input_iterator _Iter1,
+ sentinel_for<_Iter1> _Sent1,
+ input_iterator _Iter2,
+ sentinel_for<_Iter2> _Sent2,
+ class _Pred = ranges::equal_to,
+ class _Proj1 = identity,
+ class _Proj2 = identity>
+ requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
+ _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr bool operator()(
+ _Iter1 __first1,
+ _Sent1 __last1,
+ _Iter2 __first2,
+ _Sent2 __last2,
+ _Pred __pred = {},
+ _Proj1 __proj1 = {},
+ _Proj2 __proj2 = {}) {
+ return __starts_with_impl(
+ std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), __pred, __proj1, __proj2);
+ }
+
template <input_range _Range1,
input_range _Range2,
class _Pred = ranges::equal_to,
@@ -81,26 +106,14 @@ struct __fn {
requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>, _Pred, _Proj1, _Proj2>
_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI static constexpr bool
operator()(_Range1&& __range1, _Range2&& __range2, _Pred __pred = {}, _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) {
- if constexpr (sized_range<_Range1> && sized_range<_Range2>) {
- auto __n1 = ranges::size(__range1);
- auto __n2 = ranges::size(__range2);
- if (__n2 == 0) {
- return true;
- }
- if (__n2 > __n1) {
- return false;
- }
- }
-
- return __mismatch::__fn::__go(
- ranges::begin(__range1),
- ranges::end(__range1),
- ranges::begin(__range2),
- ranges::end(__range2),
- __pred,
- __proj1,
- __proj2)
- .in2 == ranges::end(__range2);
+ return __starts_with_impl(
+ ranges::begin(__range1),
+ ranges::end(__range1),
+ ranges::begin(__range2),
+ ranges::end(__range2),
+ __pred,
+ __proj1,
+ __proj2);
}
};
} // namespace __starts_with
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