From e717c322c6ee21bd5d9cf9373dcd9b4e8ba3312f Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 1 Nov 2024 21:52:37 +0000
Subject: [PATCH] libstdc++: Replace _Hashtable::__fwd_value_for with cast
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We can just use a cast to the appropriate type instead of calling a
function to do it. This gives the compiler less work to compile and
optimize, and at -O0 avoids a function call per element.
libstdc++-v3/ChangeLog:
* include/bits/hashtable.h (_Hashtable::__fwd_value_for):
Remove.
(_Hashtable::_M_assign): Use static_cast instead of
__fwd_value_for.
Reviewed-by: François Dumont <fdumont@gcc.gnu.org>
---
libstdc++-v3/include/bits/hashtable.h | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h
index bf6eed7c1c69..f1c30896bcb0 100644
--- a/libstdc++-v3/include/bits/hashtable.h
+++ b/libstdc++-v3/include/bits/hashtable.h
@@ -325,13 +325,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__node_ptr _M_node;
};
- template<typename _Ht>
- static constexpr
- __conditional_t<std::is_lvalue_reference<_Ht>::value,
- const value_type&, value_type&&>
- __fwd_value_for(value_type& __val) noexcept
- { return std::move(__val); }
-
// Compile-time diagnostics.
// _Hash_code_base has everything protected, so use this derived type to
@@ -1406,11 +1399,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (!__ht._M_before_begin._M_nxt)
return;
+ using _FromVal = __conditional_t<is_lvalue_reference<_Ht>::value,
+ const value_type&, value_type&&>;
+
// First deal with the special first node pointed to by
// _M_before_begin.
__node_ptr __ht_n = __ht._M_begin();
__node_ptr __this_n
- = __node_gen(__fwd_value_for<_Ht>(__ht_n->_M_v()));
+ = __node_gen(static_cast<_FromVal>(__ht_n->_M_v()));
this->_M_copy_code(*__this_n, *__ht_n);
_M_update_bbegin(__this_n);
@@ -1418,7 +1414,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__node_ptr __prev_n = __this_n;
for (__ht_n = __ht_n->_M_next(); __ht_n; __ht_n = __ht_n->_M_next())
{
- __this_n = __node_gen(__fwd_value_for<_Ht>(__ht_n->_M_v()));
+ __this_n = __node_gen(static_cast<_FromVal>(__ht_n->_M_v()));
__prev_n->_M_nxt = __this_n;
this->_M_copy_code(*__this_n, *__ht_n);
size_type __bkt = _M_bucket_index(*__this_n);
--
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