From 6ecf2b380da6129cd32edccdbc322dfd2884d490 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 11 Oct 2024 14:49:21 +0100
Subject: [PATCH] libstdc++: Add always_inline to some one-liners in
 <bits/stl_algobase.h>

We implement std::copy, std::fill etc. as a series of calls to other
overloads which incrementally peel off layers of iterator wrappers. This
adds a high abstraction penalty for -O0 and potentially even -O1. Add
the always_inline attribute to several functions that are just a single
return statement (and maybe a static_assert, or some concept-checking
assertions which are disabled by default).

libstdc++-v3/ChangeLog:

	* include/bits/stl_algobase.h (__copy_move_a1, __copy_move_a)
	(__copy_move_backward_a1, __copy_move_backward_a, move_backward)
	(__fill_a1, __fill_a, fill, __fill_n_a, fill_n, __equal_aux):
	Add always_inline attribute to one-line forwarding functions.

Reviewed-by: Patrick Palka <ppalka@redhat.com>
---
 libstdc++-v3/include/bits/stl_algobase.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
index 049ba4f96c4..9ecd0b216c1 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -498,12 +498,14 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     __copy_move_a1(_II, _II, _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
 
   template<bool _IsMove, typename _II, typename _OI>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OI
     __copy_move_a1(_II __first, _II __last, _OI __result)
     { return std::__copy_move_a2<_IsMove>(__first, __last, __result); }
 
   template<bool _IsMove, typename _II, typename _OI>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OI
     __copy_move_a(_II __first, _II __last, _OI __result)
@@ -755,6 +757,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
 #undef _GLIBCXX_ADVANCE
 
   template<bool _IsMove, typename _BI1, typename _BI2>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _BI2
     __copy_move_backward_a1(_BI1 __first, _BI1 __last, _BI2 __result)
@@ -783,6 +786,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
 			    _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
 
   template<bool _IsMove, typename _II, typename _OI>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OI
     __copy_move_backward_a(_II __first, _II __last, _OI __result)
@@ -838,6 +842,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
    *  that the start of the output range may overlap [first,last).
   */
   template<typename _BI1, typename _BI2>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _BI2
     copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
@@ -873,6 +878,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
    *  that the start of the output range may overlap [first,last).
   */
   template<typename _BI1, typename _BI2>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _BI2
     move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
@@ -956,6 +962,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     }
 
   template<typename _Ite, typename _Cont, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline void
     __fill_a1(::__gnu_cxx::__normal_iterator<_Ite, _Cont> __first,
@@ -975,6 +982,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
 	    const bool&);
 
   template<typename _FIte, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline void
     __fill_a(_FIte __first, _FIte __last, const _Tp& __value)
@@ -1000,6 +1008,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
    *  to @c memset or @c wmemset.
   */
   template<typename _ForwardIterator, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline void
     fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
@@ -1106,6 +1115,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
 	       std::input_iterator_tag);
 
   template<typename _OutputIterator, typename _Size, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OutputIterator
     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
@@ -1118,6 +1128,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     }
 
   template<typename _OutputIterator, typename _Size, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OutputIterator
     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
@@ -1130,6 +1141,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     }
 
   template<typename _OutputIterator, typename _Size, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OutputIterator
     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
@@ -1165,6 +1177,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
   // DR 865. More algorithms that throw away information
   // DR 426. search_n(), fill_n(), and generate_n() with negative n
   template<typename _OI, typename _Size, typename _Tp>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline _OI
     fill_n(_OI __first, _Size __n, const _Tp& __value)
@@ -1244,6 +1257,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     }
 
   template<typename _II1, typename _II2>
+    __attribute__((__always_inline__))
     _GLIBCXX20_CONSTEXPR
     inline bool
     __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
-- 
2.47.2