MSVSphere Packaging Team
6 months ago
parent
3461f8d62d
commit
025730f3b6
@ -0,0 +1,107 @@
|
||||
commit 6f5dcea85a31845ec6f4b6886734b0f02e013718
|
||||
Author: Jonathan Wakely <jwakely@redhat.com>
|
||||
Date: Tue Feb 27 17:50:34 2024 +0000
|
||||
|
||||
libstdc++: Fix conditions for using memcmp in std::lexicographical_compare_three_way [PR113960]
|
||||
|
||||
The change in r11-2981-g2f983fa69005b6 meant that
|
||||
std::lexicographical_compare_three_way started to use memcmp for
|
||||
unsigned integers on big endian targets, but for that to be valid we
|
||||
need the two value types to have the same size and we need to use that
|
||||
size to compute the length passed to memcmp.
|
||||
|
||||
I already defined a __is_memcmp_ordered_with trait that does the right
|
||||
checks, std::lexicographical_compare_three_way just needs to use it.
|
||||
|
||||
libstdc++-v3/ChangeLog:
|
||||
|
||||
PR libstdc++/113960
|
||||
* include/bits/stl_algobase.h (__is_byte_iter): Replace with ...
|
||||
(__memcmp_ordered_with): New concept.
|
||||
(lexicographical_compare_three_way): Use __memcmp_ordered_with
|
||||
instead of __is_byte_iter. Use correct length for memcmp.
|
||||
* testsuite/25_algorithms/lexicographical_compare_three_way/113960.cc:
|
||||
New test.
|
||||
|
||||
(cherry picked from commit f5cdda8acb06c20335855ed353ab9a441c12128a)
|
||||
|
||||
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
|
||||
index 7664301a208..6e648e48ad0 100644
|
||||
--- a/libstdc++-v3/include/bits/stl_algobase.h
|
||||
+++ b/libstdc++-v3/include/bits/stl_algobase.h
|
||||
@@ -1780,11 +1780,14 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
|
||||
}
|
||||
|
||||
#if __cpp_lib_three_way_comparison
|
||||
- // Iter points to a contiguous range of unsigned narrow character type
|
||||
- // or std::byte, suitable for comparison by memcmp.
|
||||
- template<typename _Iter>
|
||||
- concept __is_byte_iter = contiguous_iterator<_Iter>
|
||||
- && __is_memcmp_ordered<iter_value_t<_Iter>>::__value;
|
||||
+ // Both iterators refer to contiguous ranges of unsigned narrow characters,
|
||||
+ // or std::byte, or big-endian unsigned integers, suitable for comparison
|
||||
+ // using memcmp.
|
||||
+ template<typename _Iter1, typename _Iter2>
|
||||
+ concept __memcmp_ordered_with
|
||||
+ = (__is_memcmp_ordered_with<iter_value_t<_Iter1>,
|
||||
+ iter_value_t<_Iter2>>::__value)
|
||||
+ && contiguous_iterator<_Iter1> && contiguous_iterator<_Iter2>;
|
||||
|
||||
// Return a struct with two members, initialized to the smaller of x and y
|
||||
// (or x if they compare equal) and the result of the comparison x <=> y.
|
||||
@@ -1834,20 +1837,20 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
|
||||
if (!std::__is_constant_evaluated())
|
||||
if constexpr (same_as<_Comp, __detail::_Synth3way>
|
||||
|| same_as<_Comp, compare_three_way>)
|
||||
- if constexpr (__is_byte_iter<_InputIter1>)
|
||||
- if constexpr (__is_byte_iter<_InputIter2>)
|
||||
- {
|
||||
- const auto [__len, __lencmp] = _GLIBCXX_STD_A::
|
||||
- __min_cmp(__last1 - __first1, __last2 - __first2);
|
||||
- if (__len)
|
||||
- {
|
||||
- const auto __c
|
||||
- = __builtin_memcmp(&*__first1, &*__first2, __len) <=> 0;
|
||||
- if (__c != 0)
|
||||
- return __c;
|
||||
- }
|
||||
- return __lencmp;
|
||||
- }
|
||||
+ if constexpr (__memcmp_ordered_with<_InputIter1, _InputIter2>)
|
||||
+ {
|
||||
+ const auto [__len, __lencmp] = _GLIBCXX_STD_A::
|
||||
+ __min_cmp(__last1 - __first1, __last2 - __first2);
|
||||
+ if (__len)
|
||||
+ {
|
||||
+ const auto __blen = __len * sizeof(*__first1);
|
||||
+ const auto __c
|
||||
+ = __builtin_memcmp(&*__first1, &*__first2, __blen) <=> 0;
|
||||
+ if (__c != 0)
|
||||
+ return __c;
|
||||
+ }
|
||||
+ return __lencmp;
|
||||
+ }
|
||||
|
||||
while (__first1 != __last1)
|
||||
{
|
||||
diff --git a/libstdc++-v3/testsuite/25_algorithms/lexicographical_compare_three_way/113960.cc b/libstdc++-v3/testsuite/25_algorithms/lexicographical_compare_three_way/113960.cc
|
||||
new file mode 100644
|
||||
index 00000000000..d51ae1a3d50
|
||||
--- /dev/null
|
||||
+++ b/libstdc++-v3/testsuite/25_algorithms/lexicographical_compare_three_way/113960.cc
|
||||
@@ -0,0 +1,15 @@
|
||||
+// { dg-do run { target c++20 } }
|
||||
+
|
||||
+// PR libstdc++/113960
|
||||
+// std::map with std::vector as input overwrites itself with c++20, on s390x
|
||||
+
|
||||
+#include <algorithm>
|
||||
+#include <testsuite_hooks.h>
|
||||
+
|
||||
+int main()
|
||||
+{
|
||||
+ unsigned short a1[] { 1, 2, 3 };
|
||||
+ unsigned short a2[] { 1, 2, 4 };
|
||||
+ // Incorrect memcmp comparison for big endian targets.
|
||||
+ VERIFY( std::lexicographical_compare_three_way(a1, a1+3, a2, a2+3) < 0 );
|
||||
+}
|
||||
Loading…
Reference in new issue