[PATCH] libstdc++: Fix incorrect use of memset in ranges::fill_n (PR 94017)
Patrick Palka
ppalka@redhat.com
Tue Mar 3 21:46:00 GMT 2020
When deciding whether to perform the memset optimization in ranges::fill_n, we
were crucially neglecting to check whether the output pointer's value type is a
byte type. This patch adds such a check to the problematic condition in
ranges::fill_n.
I think the __is_byte<_Tp>::__value check, which checks that the fill type is a
byte type, is too restrictive. It means that we won't enable the memset
optimization in the following example:
char c[100];
ranges::fill(c, 37);
since the fill type is deduced to be int here. It seems we could get away
with instead just checking that _Tp is an integral type; I've added a TODO
about this in the code.
libstdc++-v3/ChangeLog:
PR libstdc++/94017
* include/bits/ranges_algobase.h (__fill_n_fn::operator()): Fix
condition for when to use memset.
* testsuite/20_util/specialized_algorithms/uninitialized_fill/94017.cc:
New test.
* testsuite/20_util/specialized_algorithms/uninitialized_fill_n/94017.cc:
New test.
* testsuite/25_algorithms/fill/94017.cc: New test.
* testsuite/25_algorithms/fill_n/94017.cc: New test.
---
libstdc++-v3/include/bits/ranges_algobase.h | 9 ++-
.../uninitialized_fill/94017.cc | 74 +++++++++++++++++++
.../uninitialized_fill_n/94017.cc | 74 +++++++++++++++++++
.../testsuite/25_algorithms/fill/94017.cc | 73 ++++++++++++++++++
.../testsuite/25_algorithms/fill_n/94017.cc | 73 ++++++++++++++++++
5 files changed, 301 insertions(+), 2 deletions(-)
create mode 100644 libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill/94017.cc
create mode 100644 libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill_n/94017.cc
create mode 100644 libstdc++-v3/testsuite/25_algorithms/fill/94017.cc
create mode 100644 libstdc++-v3/testsuite/25_algorithms/fill_n/94017.cc
diff --git a/libstdc++-v3/include/bits/ranges_algobase.h b/libstdc++-v3/include/bits/ranges_algobase.h
index feb6c5723dd..35309986e53 100644
--- a/libstdc++-v3/include/bits/ranges_algobase.h
+++ b/libstdc++-v3/include/bits/ranges_algobase.h
@@ -531,8 +531,13 @@ namespace ranges
if (__n <= 0)
return __first;
- // TODO: is __is_byte the best condition?
- if constexpr (is_pointer_v<_Out> && __is_byte<_Tp>::__value)
+ // TODO: Generalize this optimization to contiguous iterators.
+ if constexpr (is_pointer_v<_Out>
+ // Note that __is_byte already implies !is_volatile.
+ && __is_byte<remove_pointer_t<_Out>>::__value
+ // TODO: Can we relax this next condition to just
+ // integral<_Tp>?
+ && __is_byte<_Tp>::__value)
{
__builtin_memset(__first, static_cast<unsigned char>(__value), __n);
return __first + __n;
diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill/94017.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill/94017.cc
new file mode 100644
index 00000000000..c039935d78e
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill/94017.cc
@@ -0,0 +1,74 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <algorithm>
+#include <memory>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_output_range;
+
+namespace ranges = std::ranges;
+
+template<typename Out, auto value>
+void
+test01()
+{
+ {
+ Out x[5];
+ ranges::uninitialized_fill(x, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+
+ {
+ Out x[5];
+ test_output_range<Out> rx(x);
+ ranges::uninitialized_fill(x, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+}
+
+int
+main()
+{
+ test01<char, 100>();
+ test01<char, 150>();
+ test01<char, 300>();
+ test01<char, 1000>();
+ test01<char, -10000L>();
+
+ test01<signed char, 100>();
+ test01<signed char, 150>();
+ test01<signed char, 300>();
+
+ test01<unsigned char, 100>();
+ test01<unsigned char, 150>();
+ test01<unsigned char, 300>();
+
+ test01<int, 'a'>();
+ test01<int, u8'a'>();
+ test01<int, (signed char)'a'>();
+ test01<int, (unsigned char)'a'>();
+
+ test01<volatile int, 'a'>();
+ test01<volatile int, 'a'>();
+ test01<volatile int, 500>();
+ test01<volatile char, 500>();
+}
diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill_n/94017.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill_n/94017.cc
new file mode 100644
index 00000000000..e7928295a82
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_fill_n/94017.cc
@@ -0,0 +1,74 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <algorithm>
+#include <memory>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_output_range;
+
+namespace ranges = std::ranges;
+
+template<typename Out, auto value>
+void
+test01()
+{
+ {
+ Out x[5];
+ ranges::uninitialized_fill_n(x, 5, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+
+ {
+ Out x[5];
+ test_output_range<Out> rx(x);
+ ranges::uninitialized_fill_n(x, 5, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+}
+
+int
+main()
+{
+ test01<char, 100>();
+ test01<char, 150>();
+ test01<char, 300>();
+ test01<char, 1000>();
+ test01<char, -10000L>();
+
+ test01<signed char, 100>();
+ test01<signed char, 150>();
+ test01<signed char, 300>();
+
+ test01<unsigned char, 100>();
+ test01<unsigned char, 150>();
+ test01<unsigned char, 300>();
+
+ test01<int, 'a'>();
+ test01<int, u8'a'>();
+ test01<int, (signed char)'a'>();
+ test01<int, (unsigned char)'a'>();
+
+ test01<volatile int, 'a'>();
+ test01<volatile int, 'a'>();
+ test01<volatile int, 500>();
+ test01<volatile char, 500>();
+}
diff --git a/libstdc++-v3/testsuite/25_algorithms/fill/94017.cc b/libstdc++-v3/testsuite/25_algorithms/fill/94017.cc
new file mode 100644
index 00000000000..d2d59f927e4
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/fill/94017.cc
@@ -0,0 +1,73 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_output_range;
+
+namespace ranges = std::ranges;
+
+template<typename Out, auto value>
+void
+test01()
+{
+ {
+ Out x[5];
+ ranges::fill(x, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+
+ {
+ Out x[5];
+ test_output_range<Out> rx(x);
+ ranges::fill(x, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+}
+
+int
+main()
+{
+ test01<char, 100>();
+ test01<char, 150>();
+ test01<char, 300>();
+ test01<char, 1000>();
+ test01<char, -10000L>();
+
+ test01<signed char, 100>();
+ test01<signed char, 150>();
+ test01<signed char, 300>();
+
+ test01<unsigned char, 100>();
+ test01<unsigned char, 150>();
+ test01<unsigned char, 300>();
+
+ test01<int, 'a'>();
+ test01<int, u8'a'>();
+ test01<int, (signed char)'a'>();
+ test01<int, (unsigned char)'a'>();
+
+ test01<volatile int, 'a'>();
+ test01<volatile int, 'a'>();
+ test01<volatile int, 500>();
+ test01<volatile char, 500>();
+}
diff --git a/libstdc++-v3/testsuite/25_algorithms/fill_n/94017.cc b/libstdc++-v3/testsuite/25_algorithms/fill_n/94017.cc
new file mode 100644
index 00000000000..3cfaf39301a
--- /dev/null
+++ b/libstdc++-v3/testsuite/25_algorithms/fill_n/94017.cc
@@ -0,0 +1,73 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do run { target c++2a } }
+
+#include <algorithm>
+#include <testsuite_hooks.h>
+#include <testsuite_iterators.h>
+
+using __gnu_test::test_output_range;
+
+namespace ranges = std::ranges;
+
+template<typename Out, auto value>
+void
+test01()
+{
+ {
+ Out x[5];
+ ranges::fill_n(x, 5, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+
+ {
+ Out x[5];
+ test_output_range<Out> rx(x);
+ ranges::fill_n(x, 5, value);
+ VERIFY( ranges::count(x, static_cast<Out>(value)) == ranges::size(x) );
+ }
+}
+
+int
+main()
+{
+ test01<char, 100>();
+ test01<char, 150>();
+ test01<char, 300>();
+ test01<char, 1000>();
+ test01<char, -10000L>();
+
+ test01<signed char, 100>();
+ test01<signed char, 150>();
+ test01<signed char, 300>();
+
+ test01<unsigned char, 100>();
+ test01<unsigned char, 150>();
+ test01<unsigned char, 300>();
+
+ test01<int, 'a'>();
+ test01<int, u8'a'>();
+ test01<int, (signed char)'a'>();
+ test01<int, (unsigned char)'a'>();
+
+ test01<volatile int, 'a'>();
+ test01<volatile int, 'a'>();
+ test01<volatile int, 500>();
+ test01<volatile char, 500>();
+}
--
2.25.1.460.g2f268890c2
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